Ultra-high power efficiency organic light-emitting diodes based on hot-exciton-assisted exciplex (HEAE) system

Ultra-high power efficiency organic light-emitting diodes based on hot-exciton-assisted exciplex (HEAE) system | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Ultra-high power efficiency organic light-emitting diodes based on hot-exciton-assisted exciplex (HEAE) system Zhiming Wang, Jingli Lou, Junwei He, Baoxi Li, Yichao Chen, Han Zhang, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6904824/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Power efficiency (PE) is crucial for evaluating organic light-emitting diode (OLED) performance, as it directly reflects photoelectric conversion efficiency. Exciplexes, featuring low injection barriers, offer greater potential than single compounds for high PE, but slow exciton dynamics hinder their development. Here, we introduce a novel strategy of hot-exciton-assisted exciplex (HEAE), which enhances the electroluminescence performance of exciplex systems from aspects of exciton and carrier dynamics. The feature of recovered exciton energy and accelerated reverse intersystem crossing process driven by the hot-exciton material improved the exciton utilization within the exciplex. As a result, the concepted exciplex showsa twice external quantum efficiency (EQE) of 19.0% than exciplex systems composed of conventional materials. Meanwhile, the moderate electron mobilityof hot-exciton material facilitates carrier transportbetween donors, enabling barrier-free injection in concepted exciplex-based OLEDs, which achieve a maximum PE up to82.1 lm W⁻¹. To further prove the superiority of the HEAE system, the exciplex-sensitized fluorescence OLEDs with narrow emission are designed, affording high EQEs of up to 40.5% and setting a new record for breakthrough PE exceeding 230 lm W⁻¹. Physical sciences/Optics and photonics/Lasers, LEDs and light sources/Organic LEDs Physical sciences/Physics/Electronics, photonics and device physics/Photonic devices organic light-emitting diode power efficiency exciton utilization exciplex hot-exciton Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Organic light-emitting diodes (OLEDs) are widely used in the fields of display and illumination due to their unique advantages, such as flexibility, high resolution, and low power consumption 1,2 . As the awareness of energy conservation is deeply rooted in individuals, the demands regarding low-power-consumption electronic products are increasing. In general, the power consumption of an OLED is described by power efficiency (PE, η P ), which is related to external quantum efficiency (EQE, η EQE ), average photon energy ( Ē ), and driving voltage ( U ). $$\:{\eta\:}_{P}=\text{E}\text{Q}\text{E}\bullet\:\frac{\stackrel{-}{E}\:\left(eV\right)}{U\left(V\right)}$$ 1 With the same Ē , a higher PE can be obtained by endowing the OLED with a higher EQE and a lower U . Using the heavy-atom effect or reverse intersystem crossing (RISC) process in a single molecule, a maximum EQE of 20–40% can be realized. Nevertheless, simultaneously achieving a low U is difficult for a single molecule due to the energy level barriers usually exist between the emitting materials layer (EML) and adjacent functional layers, resulting in a U exceeding the bandgaps of emitters. Therefore, the OLEDs with PE ≥ 200 lm W − 1 are still rare. Other than the donor and acceptor concentrated within a single molecule, the luminescent system where donor and acceptor are distributed on different molecules, respectively, commonly referred to as an exciplex, has also realized high EQE through the RISC process driven by an intermolecular charge transfer (CT) interaction 3 . Typically, the donor molecule in the exciplex system (donor for short) is hole-dominant, and the acceptor molecule in the exciplex system (acceptor for short) is electron-dominant, resulting in a low energy level barrier with adjacent layers. Hence, exciplex is an ideal candidate to match the demand for high-PE OLED 4,5 . However, the slow RISC process of conventional exciplex generally causes severe exciton quenching and a low exciton utilization 6 . To address this, various strategies have been proposed to enhance the exciton utilization of exciplex. Although the RISC process in exciplex systems composed of conventional material (C-type exciplex) can be accelerated via spin–orbit coupling (SOC) effect, this requires the locally excited triplet states (³LE) of the donor or acceptor strictly limited adjacent to the CT-dominated singlet ( 1 CT) and triplet (³CT) states 7–9 . Recently, introducing additional RISC channels has become another way to improve exciton utilization of exciplex by recovering excitons recombined at the donors or acceptors 10 . For example, Zhang et al. applied a thermally activated delayed fluorescence (TADF) material named MAC as the donor of exciplexes, preparing OLEDs with high efficiency and low-efficiency roll-off 11 . Moreover, featuring low-lying 3 LE states and rapid high-lying RISC channels, hot-exciton materials are ideal candidates for assisting exciplex from both the SOC effect and additional RISC channels. Unfortunately, only a few exciplex systems containing hot-exciton materials (H-type exciplex) have been reported; however, a comprehensive investigation is rarely explored to explain the underlying mechanisms 12,13 . And we note that hot-exciton materials were used as acceptors for exciplex and have not yet been used as donors. In addition, the conventional donor and acceptor materials usually feature extremely unipolar transport, impeding carrier transfer between donor and donor or acceptor and acceptor in exciplex. Although resolving this issue is essential for facilitating carrier injection and promoting exciton recombination, it has received little attention. Herein, we developed a hot-exciton-assisted exciplex (HEAE) system, which exhibited high exciton utilization, barrier-free carrier injection, and a wide exciton recombination area in electroluminescence (EL). Three hot-exciton materials—2MCz-CNMCz, 2 t -2MCz-CNMCz, and 4 t -2MCz-CNMCz—were used as donors—combined with 2,4,6-tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine (PO-T2T) to construct exciplexes H1, H2, and H3, respectively. Owing to the low-lying 3 LE states and the high-lying RISC channels of the three hot-exciton materials, the RISC process was accelerated by the SOC effect under an electric field, and effective exciton utilization was achieved through the Förster resonance energy transfer (FRET) process (Fig. 1 ). Consequently, OLEDs based on H1 showed green emissions with twice the maximum external quantum efficiency (EQE) of C-type exciplexes. Introducing a third component to fine-tune the horizontal dipole orientation ( Θ ∥ ) of H1, the maximum EQE and PE were enhanced to 19.0% and 82.1 lm W ─1 , respectively. Magneto-EL (MEL) curves demonstrated that the RISC originated from the SOC effect and was regulated via peripheral tert -butyl groups on the hot-exciton materials. Detection of exciton recombination regions in H1-based OLED confirmed a wide exciton recombination area of exciplex H1. Therefore, exciplex H1 was applied as a sensitized host of four multiple-resonance TADF (MR-TADF) emitters. As a result, four sensitized devices with maximum EQEs of 37.7%, 40.5%, 30.7%, and 33.4% and PEs of 232.8, 223.5, 176.6, and 203.6 lm W − 1 were designed, respectively. These results confirm efficient conversion of electrically generated excitons into luminescence in the HEAE system, providing an effective method for obtaining OLEDs with high PE. Results Photophysical properties Blue-violet materials with high T 1 levels are commonly selected as donors or acceptors to prevent back energy transfer, in which carbazole derivatives featuring wide bandgaps, excellent hole transport, and molecular planarity are ideal candidates 14 . The reported hot-exciton carbazole derivative 2MCz-CNMCz, with a high T 1 energy of 2.69 eV, high hole mobility of 2.8 × 10 − 3 cm 2 V − 1 s − 1 , and exciton utilization rate of 77.1%, is chosen as the donor 15 . Different quantities of tert -butyl groups are introduced into 2MCz-CNMCz, expecting to regulate the SOC effect in the exciplex. Here, two tailor-made molecules, 2 t -2MCz-CNMCz and 4 t -2MCz-CNMCz, are designed and evaluated. Their specific synthesis routes are described in the Supporting Information. The photoluminescence (PL) properties of 2 t -2MCz-CNMCz and 4 t -2MCz-CNMCz were evaluated (Fig. S1 and Table S1 –S3). Based on the onset energies of the fluorescence and phosphorescence spectra at 77 K in toluene, the S 1 and T 1 energy levels are estimated to be 3.29 and 2.68 eV for 2 t -2MCz-CNMCz and 3.32 and 2.77 eV for 4 t -2MCz-CNMCz, corresponding to large energy gap (Δ E S1–T1 ) values of 0.61 and 0.55 eV, respectively. Compared to 2MCz-CNMCz, the introduction of tert -butyl into 2 t -2MCz-CNMCz and 4 t -2MCz-CNMCz has minimal effects on the PL properties, and the large Δ E S1–T1 excludes the TADF mechanism. Natural transition orbital simulation confirmed that the T 1 states of both 2 t -2MCz-CNMCz and 4 t -2MCz-CNMC are LE-dominated (Fig. S2 and Table S4–S5). Based on the energy level distributions of singlet and triplet states, hot-exciton channels are presumed to exist in both molecules (Fig. S3) 16 . Herein, three hot-exciton molecules—2MCz-CNMCz, 2 t -2MCz-CNMCz, and 4 t -2MCz-CNMCz—are employed as donors to form exciplexes with the high-triplet (T 1 = 3.0 eV) materials PO-T2T as the acceptor, yielding H1, H2, and H3, respectively. The HOMO and LUMO energy levels of the 2MCz-CNMCz, 2 t -2MCz-CNMCz, and 4 t -2MCz-CNMCz are − 5.35 and − 2.28 eV, − 5.53 and − 2.24 eV, and − 5.54 and − 2.24 eV, respectively, matching with the HOMO (− 7.5 eV) and LUMO (− 3.5 eV) of PO-T2T (Fig. S4) 17 . To enable a systematic investigation of the proposed concept, five conventional donors—including carbazole and triphenylamine derivatives (mcp, m CBP, TcTa, TAPC, and Tris-PCz) —are also selected to form exciplexes with PO-T2T in Fig. 2 , named C1, C2, C3, C4, and C5, respectively 18–22 . The PL properties of all donor–acceptor mixtures were evaluated in films using an optimized ratio of 40 wt% donor to 60 wt% acceptor. All mixtures showed broad absorption tails extending to 600 nm, attributed to intermolecular CT transitions. Mixtures H1, H2, and H3 exhibited green emission, clearly distinct from the spectra of either donor or PO-T2T (Fig. S5), confirming the formation of exciplex. Transient PL decay curves for H1, H2, and H3 revealed typical biexponential decay profiles comprising prompt ( τ P ) and delayed ( τ D ) components, further confirming exciplex generation. The photoluminescence quantum yield (PLQY) values of exciplexes H1, H2, and H3 were 37.4%, 44.9%, and 38.8%, respectively. When the temperature dropped to 77 K, all H-type and C-type exciplexes showed long-lived phosphorescence emissions (Fig. S6). As shown in Table 1 , three H-type exciplexes showed Δ E S1–T1 values of 0.23, 0.26, and 0.27 eV, respectively, while the Δ E S1–T1 s of five C-type exciplexes were almost zero. As shown in Fig. 2 c, the energy levels of 3 LE states of hot-exciton materials are located between the 1 CT and 3 CT states of exciplexes. It is speculated that the SOC effect between the 3 LE and CT states promotes the spin-mixing between 1 CT and 3 CT states. Moreover, the high-lying RISC process in hot-exciton materials is expected to recover exciton energy for exciplexes. However, the k RISC values evaluated by transient PL decay curves for the H1, H2, and H3 exciplexes were 1.5 × 10 5 , 1.8 × 10 5 , and 1.0 × 10 5 s − 1 , respectively, suggesting slow RISC processes in PL. By contrast, the k RISC values of C-type exciplexes evaluated by the transient PL decay curves ranged from 2.0 ~ 4.4 × 10 6 s − 1 (Fig. S7). Table 1 Photophysical characteristics of exciplex films. Exciplex λ abs a (nm) λ max a (nm) PLQY a (%) τ P b (ns) τ D b (µs) R delayed c (%) k r c (× 10 6 s ‒1 ) k IC c (× 10 6 s ‒1 ) k ISC c (× 10 7 s ‒1 ) k RISC c (× 10 6 s ‒1 ) E S1 / E T1 / Δ E S1T1 d (eV) H1 352 521 37.4 16.6 33.8 79.7 4.6 7.6 4.8 0.2 2.68 /2.45/0.23 H2 354 514 44.9 22.6 140.0 91.1 1.8 2.2 4.0 0.1 2.76 /2.50/0.26 H3 352 507 38.8 22.0 160.1 90.3 1.7 2.6 4.0 0.1 2.80 /2.53/0.27 C1 328 475 39.3 44.0 4.5 88.7 1.0 1.6 2.0 2.0 2.92/2.87/0.05 C2 343 476 39.6 43.7 3.8 87.9 1.1 1.7 2.0 2.1 2.92/2.92/0.00 C3 335 542 20.8 55.1 1.2 72.4 1.4 4.0 1.3 4.4 2.58/2.57/0.01 C4 282 562 13.1 59.8 1.5 84.4 0.3 2.3 1.4 3.1 2.48/2.46/0.02 C5 309 535 12.8 47.8 1.4 82.2 0.5 3.3 1.7 4.0 2.57/2.57/0.00 a The characteristic absorption peaks, emission peaks, and photoluminescence quantum yield (PLQY) in nitrogen environment of exciplex films. b Fitting from the transient PL decay curves of exciplex film. c Deduced from the PLQY and transient PL decay curves. d Determined from the onset of PL and phosphorescence spectra in film at 77K. Electroluminescent performance OLEDs with different EMLs were designed and fabricated with the structures shown in Fig. 3 : ITO (90 nm)/HATCN (5 nm)/TAPC (50 nm)/TcTa (5 nm)/EML (20 nm)/PO-T2T (50 nm)/LiF (1 nm)/Al (120 nm), where HATCN, TAPC, and TcTa are 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile, 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane, and tris(4-(9H-carbazol-9-yl)phenyl)amine, respectively. The EMLs included H-type exciplexes (devices H1, H2, and H3) and C-type exciplexes (devices C1, C2, C3, C4, and C5). The device H1–H3 showed low turn-on voltages ( V on ) of 2.2, 2.2, and 2.3 V, and the device C1–C5 showed V on s of 2.8, 2.4, 2.2, 2.2, and 2.2 V. As shown in Table 2 , the V on values of device H1–H3 were lower than their photon energy of wavelength peak of EL spectra ( E λ ), while the V on of devices C1–C5 were higher than or close their E λ values, indicating H-type exciplexes achieved a better carrier injection than C-type exciplexes. Devices H1, H2, and H3 exhibited green emission with peak emission wavelengths ( λ EL ) of 532, 532, and 526 nm, respectively, and maximum EQEs of 13.5%, 11.6%, and 10.0%. For devices C1–C5, the λ EL values were 528, 528, 546, 572, and 560 nm, and the maximum EQEs were 6.9%, 5.7%, 7.4%, 4.3%, and 6.3%, respectively. Notably, H-type exciplexes demonstrated maximum EQEs 2–3 times higher than those of devices C1–C5. This improvement is attributed to the hot-exciton channels in the donor materials, which help recover exciton energy captured by the donor molecules. In addition, improving the Θ ∥ of exciplexes has proved to boost the optical outcoupling efficiency ( η out ) of devices 23,24 . By incorporating an inert materials DPEPO ([2-(diphenylphosphino)phenyl]ether oxide) as spacer into exciplex H1 at different ratios, the Θ ∥ of H1 improved from 54.6–66.7%, resulting in a substantial increase in η out from 25.8–34.3% (Fig. S8 and Table S6). However, the incorporation of spacers also impeded the carrier transport in EML and increased the V on of devices. Consequently, device D1 with moderate spacers (EML composed of 50 wt% exciplex H1 and 50 wt% DPEPO) maintained a green emission ( λ EL of 526 nm) and achieved a maximum EQE of 19.0% and PE of 82.1 lm W − 1 . Exciton dynamics and charge carrier To explore the effect of introducing tert- butyl on exciton dynamics in H-type exciplexes, the magnetic field effects at different current densities were measured (Fig. S9 and Table S7). As shown in Fig. 4 a, under the external magnetic field, the MEL line shapes of devices H1, H2, and H3 increased continuously. The maximum half-widths of the MEL curves of devices H1, H2, and H3 were larger than those caused by hyperfine interaction (HFI) (< 10 mT), indicating that the magnetic field effect was governed by the SOC effect and derived from the low-lying 3 LE state of the hot-exciton materials and the CT states of the exciplexes 9,25,26 . The MEL curves at different current densities were fitted by the Δ g factor model, and the fitted curves were completely consistent with the data obtained from the measurement 27 . The fitting constant ( C ) values of devices H1 to H3 were 0.135, 0.122, and 0.100, respectively, suggesting an increased SOC effect. Herein, the effect of SOC in exciplex was effectively regulated by introducing tert -butyl groups in donors. The excellent carrier injection in devices H1, H2, and H3 was further investigated by fabricating electron-only devices (EODs) and hole-only devices (HODs) of 2MCz-CNMCz, 2 t -2MCz-CNMCz, and 4 t -2MCz-CNMCz. The three molecules not only exhibited high hole carrier mobilities ( µ h ) at the magnitude of 10 − 3 cm 2 V − 1 s − 1 (Table S8), but also exhibited well electron carrier mobilities ( µ e ) at the magnitude of 10 − 4 cm 2 V − 1 s − 1 (Fig. 4 b), which were different from the conventional donors featuring unipolar transport properties. Consequently, three H-type exciplexes demonstrated V on s lower than their E λ , achieving a barrier-free carrier injection. Furthermore, an orange fluorescence emitter, 2,8-di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyltetracene (TBRb), was used as a detector to study carrier recombination in device H1 28 . As shown in Fig. 4 c, the absorption spectrum of TBRb closely overlapped with the PL spectrum of H1 exciplex, indicating efficient FRET from H1 to TBRb. An ultrathin (0.2 nm) layer of TBRb was inserted into the EML of device H1 at various positions, and the relative emission intensity of TBRb was recorded to plot the relative intensity–position–voltage graph. The relative emission intensity of TBRb was evenly distributed across the entire EML during different operation voltages, demonstrating a wide and evenly distributed exciton recombination area within the exciplex H1 (Fig. S10). Sensitization performance Owing to the efficient exciton utilization, excellent carrier injection, and wide exciton recombination area, exciplex H1 was an ideal candidate for sensitized hosts. MR-TADF emitters with narrow full-width at half maximum (FWHM) show great potential for ultrahigh-definition OLED displays 29 . However, the slow RISC process hindered the development of MR-TADF 30 . Sensitized emission, which uses MR-TADF as the terminal emitter and materials with a high exciton utilization as sensitizers, enabled the OLEDs with both ultrahigh PE and narrow emission by transferring energy from the sensitizers to the emitter 31 . Herein, the HEAE sensitized fluorescence (HESF) concept was proposed, which includes the HEAE system as a host and a fluorescent dopant. As shown in Fig. 5 , energy is transferred from the HEAE system to the dopants via FRET, using a low dopant concentration of 1 wt% to avoid Dexter energy transfer (DET). Four MR-TADF materials with high PLQYs and narrow-emission spectra—BN2, BN3, tCzphB-Ph, and tCzphB-Fl—were doped into H1 as terminal emitters 32,33 . The absorption bands of four dopants overlapped with the PL emission of H1, and the sensitized films exhibited λ EL values at 543, 565, 525, and 537 nm with FWHM values of 43, 40, 30, and 31 nm, respectively (Fig. S11). As shown in Fig. 5 b, the energy transfer processes in sensitized films were investigated through transient PL measurements, revealing a reduction in delayed lifetime and corresponding k RISC rates of 1.1 × 10 6 , 3.0 × 10 6 , 1.1 × 10 6 , and 5.5 × 10 6 s − 1 for BN2, BN3, tCzphB-Ph, and tCzphB-Fl, respectively, indicating efficient FRET from H1 to the dopants. Devices were fabricated with the same configuration above, using EMLs of H1: 1 wt% BN2 (device S1), H1: 1 wt% BN3 (device S2), H1: 1 wt% tCzphB-Ph (device S3), and H1: 1 wt% tCzphB-Fl (device S4). As shown in Table 2 , the V on values of devices S1–S4 were 2.1, 2.1, 2.2, and 2.2 V, which were lower than their E λ values, respectively. Devices S1–S4 exhibited single peaks at λ EL of 544, 568, 526, and 534 nm with narrow FWHM values of 46, 42, 33, and 33 nm, respectively. Devices S1–S4 achieved excellent maximum EQEs of 37.7%, 40.5%, 30.7%, and 33.4% and record-breaking PE values of 232.8, 223.5, 176.6, and 203.6 lm W − 1 , respectively (Table S9). Such low- V on s and high-efficiencies should be ascribed to the barrier-free injection and excellent exciton utilization on the HEAE system, showing the advantages of this strategy. Table 2 Device performance of OLEDs. Device λ EL (nm) E λ a (eV) V on b (V) L c (cd m ─2 ) CE max d (cd A ─1 ) PE max e (lm W ─1 ) EQE max f (%) CIE (x, y) g H1 532 2.33 2.2 6632 45.3 64.7 13.5 0.341, 0.576 H2 532 2.33 2.2 4611 38.7 52.9 11.6 0.340, 0.572 H3 526 2.36 2.3 4275 31.8 43.1 10.0 0.300, 0.549 C1 528 2.35 2.8 7859 22.3 25.1 6.9 0.310, 0.524 C2 528 2.35 2.4 7665 18.4 20.6 5.7 0.318, 0.533 C3 546 2.27 2.2 27460 24.1 30.4 7.4 0.402, 0.566 C4 572 2.17 2.2 13210 11.4 13.8 4.3 0.495, 0.497 C5 560 2.21 2.2 26630 18.7 23.1 6.3 0.447, 0.534 D0 528 2.35 2.3 5168 57.4 78.4 17.6 0.325, 0.566 D1 526 2.36 2.3 4172 60.1 82.1 19.0 0.305, 0.556 D2 522 2.38 2.5 3331 52.5 66.0 16.9 0.297, 0.542 S1 544 2.28 2.1 20620 155.6 232.8 37.7 0.336, 0.638 S2 568 2.18 2.1 26430 149.4 223.5 40.5 0.464, 0.529 S3 526 2.36 2.2 19680 123.7 176.6 30.7 0.237, 0.703 S4 534 2.32 2.2 19160 142.6 203.6 33.4 0.279, 0.682 a Photon energy of wavelength peak of EL spectrum. b Turn-on voltage ≥ 1 cd m ─2 . c Maximum luminance. d Maximum current efficiency. e Maximum PE. f Maximum EQE. g Commission internationale de l'éclairage, recorded at 10 mA cm − 2 . Discussion Herein, hot-exciton materials featuring low-lying LE-dominated T 1 states and fast high-lying RISC channels were proved as excellent candidates for high-performance exciplexes. And we revealed the underlying mechanism that RISC-acceleration and exciton-recovery effects of hot-exciton materials in HEAE systems. As a result, the exciplex H1 demonstrated a maximum EQE of 19.0% and PE of 82.1 lm W ─1 , double that of the C-type exciplex. In addition, the method of regulating the SOC interactions of exciplexes was offered by introducing tert -butyl groups into the donor material, and the barrier-free injection and wide exciton recombination area of the HEAE system were demonstrated. Considering the commercial demand for narrow emission, four sensitized devices were successfully prepared and obtained unexpected efficiencies, further validating the applicability of the HEAE strategy. Thus, we proved a new strategy for achieving both narrow emission and high PE, surpassing previous performance records, providing valuable insights into the rational design for low-power-consumption OLEDs. Materials and methods General information All chemicals and reagents were purchased from commercial sources and used as received. The final product underwent vacuum sublimation to improve purity before measuring its PL and EL properties. 1 H and 13 C NMR spectra were recorded on a Bruker AV 500 spectrometer in CD 2 Cl 2 at room temperature. High-resolution mass spectroscopy was performed on a GCT premier CAB048 mass spectrometer operating in MALDITOF mode. Computational methods All density functional theory (DFT) calculations were performed using the Gaussian 16 package. The optimized S 0 geometry and single-point properties at S 0 were calculated using the DFT method at the M06-2X/6-31G (d,p) level 34 . The S 1 geometry was optimized using time-dependent DFT (TD-DFT) at the M06-2X/6-31G (d,p) level. NTO and energy levels of the first five S 1 and T 1 states were calculated based on the S 1 geometry at the M06-2X/6-31G(d,p) level to understand the excited-state properties. Photophysical property measurements Solutions with a concentration of 1 × 10 −5 M were prepared for the solution measurements. All organic films used for the PL measurements were deposited onto clean quartz substrates via thermal evaporation at 1–1.5 Å s −1 under high vacuum with a base pressure of < 10 −5 torr. Ultraviolet–visible (UV–vis) absorption spectra were measured on a Shimadzu UV-2600 spectrophotometer. PL spectra were recorded on a Horiba Fluoromax-4 spectrofluorometer. PLQYs were measured using a Hamamatsu absolute PL quantum yield spectrometer (C11347 Quantaurus_QY). Transient PL decay curves were measured using an Edinburgh Instrument FLS1000 spectrometer. Electrochemical and thermal stability measurements Cyclic voltammetry was conducted on a CHI 610E A14297 using a solution of tetra- n -butylammonium hexafluorophosphate (Bu 4 NPF 6 ) (0.1 M) in dichloromethane or dimethylformamide at a scan rate of 100 mV s −1 . A platinum wire was used as the auxiliary electrode, a glass carbon disk as the working electrode, and Ag/Ag + as the reference electrode, with the redox couple ferricenium/ferrocene (Fc/Fc + ) serving as the calibration standard. The ionization potential (IP CV ) and electron affinities (EA CV ) of these molecules were calculated using the following formulas: IP CV = ( E ox − E 1/2 (Fc/Fc + ) + 4.8) eV and EA CV = ( E red − E 1/2 (Fc/Fc + ) + 4.8) eV, where E ox and E red represent the onset oxidation potential and reduction potential relative to Fc/Fc + (4.8 eV), respectively. Thermogravimetric analysis was performed on a Netzsch TG 209 under nitrogen flow at a heating rate of 10°C min − 1 . Differential scanning calorimetric (DSC) was performed on a Netzsch DSC 200 F3 under nitrogen flow at a heating rate of 10°C min − 1 . OLED fabrication and characterization The glass substrates, precoated with a 90 nm layer of ITO with a sheet resistance of 15 to 20 ohms per square, were successively cleaned in ultrasonic bath of acetone, isopropanol, detergent, and deionized water, respectively, with each step lasting 10 min. Then, the substrates were completely dried in a 70°C oven. To improve the hole injection ability of ITO, the substrates underwent O 2 plasma treatment for 6 min before fabrication. The vacuum-deposited OLEDs were fabricated under a pressure of < 5 × 10 −4 Pa in the Suzhou Fangsheng FS-380 vacuum deposition system. Organic materials, LiF, and Al were deposited at rates of 0.5 to 1.5 A, 0.1, and 3 A s −1 , respectively. The effective emitting area of the device was 9 mm 2 , determined by the overlap between the anode and cathode. EL spectra, luminance‒voltage‒current density, and EQE were characterized with a dual-channel Keithley 2400 source meter and a PR-670 spectrometer. All characterizations were conducted at room temperature and in ambient conditions without encapsulation, immediately after fabrication. Declarations D ata availability The data that support the findings of this study are available from the corresponding author upon reasonable request. Acknowledgments We are grateful for financial support from the National Natural Science Foundation of China (52473173), Natural Science Foundation of Guangdong Province (2022B1515020084), Guangdong Basic and Applied Basic Research Foundation (2023B1515040003), Key Project of Yunnan Provincial Department of Science and Technology (202303AC100021), Independent Research Project of State Key Lab of Luminescent Materials and Devices (SCUT) (Skllmd-2024-10，Skllmd-2025-05), Science and Technology Program of Guangzhou (2023A04J0988) and Key-Area Research and Development Program of Guangdong Province (2024B0101040001). Author contributions J. Lou and J. He contributed equally. Conceptualization: J. Lou, J. He and H. Zhang; Methodology: J. Lou, Y. Chen and H. Zhang; Investigation: J. Lou, B. Li and J. He; Writing – Original Draft: J. Lou, and H. Zhang; Writing – Review & Editing: H. Zhang, and Z. Wang; Funding Acquisition: Z. Wang and B. Z. Tang; Resources: Z. Wang and B. Z. Tang; Supervision: Z. Wang and B. Z. Tang. Competing interests The authors declare no competing interests. References Hu, Y. X. et al. Efficient selenium-integrated TADF OLEDs with reduced roll-off, Nat. Photon . 16 , 803−810 (2022). Chen, G. et al. High-power-efficiency and ultra-long-lifetime white OLEDs empowered by robust blue multi-resonance TADF emitters, Light Sci . Appl . 14 , 81 (2025). Goushi, K., Yoshida, K., Sato, K., & Adachi, C. Organic light-emitting diodes employing efficient reverse intersystem crossing for triplet-to-singlet state conversion , Nat. Photon. 6 , 253−258 (2012). Salehi1, A. et al. Realization of high-efficiency fluorescent organic light-emitting diodes with low driving voltage, Nat. Commun. 10 , 2305 (2019). Seino, Y., Sasabe, H., Pu, Y.-J., & Kido, J. High-performance blue phosphorescent OLEDs using energy transfer from exciplex, Adv. Mater. 26 , 1612−1616 (2014). Sun, J. et al. Exceptionally stable blue phosphorescent organic light-emitting diodes, Nat. Photon. 16 , 212–218 (2022). Moon, C.-K., Huh, J.-S., Kim, J.-M., & Kim, J.-J. Electronic structure and emission process of excited charge transfer states in solids, Chem. Mater. 30 , 5648−5654 (2018). Chapran, M. et al. Realizing 20% external quantum efficiency in electroluminescence with efficient thermally activated delayed fluorescence from an exciplex, ACS Appl. Mater. Interfaces 11 , 13460−13471 (2019). Wang, M. et al. Revealing the cooperative relationship between spin, energy, and polarization parameters toward developing high-efficiency exciplex light-emitting diodes, Adv. Mater. 31 , 1904114 (2019). Nguyen, T. B., Nakanotani, H., Hatakeyama, T., & Adachi, C. The role of reverse intersystem crossing using a TADF-type acceptor molecule on the device stability of exciplex-based organic light-emitting diodes, Adv. Mater. 32 , 1906614 (2020). Zhang, M. et al. Tricomponent exciplex emitter realizing over 20% external quantum efficiency in organic light-emitting diode with multiple reverse intersystem crossing channels, Adv. Funct. Mater. 26 , 2002−2008 (2016). Yin, Y. et al. HLCT-type acceptor molecule-based exciplex system for highly efficient solution-processable OLEDs with suppressed efficiency roll-offs, Adv. Mater. 36 , 2313656 (2024). Xie, M. et al. Efficient and multifunctional electroluminescent ultra deep-blue material with hybrid localization and charge transfer, Adv. Funct. Mater. 2422822 (2025). Huang, T. et al. Delocalizing electron distribution in thermally activated delayed fluorophors for high-efficiency and long-lifetime blue electroluminescence, Nat . Mater . 23 , 1523–1530 (2024). Guo, X. et al. New-fashioned universal and functional host-material from a near-ultraviolet organic emitter for high-efficiency organic light-emitting diodes with low efficiency roll-offs, Small, 18 , 2204029 (2022). Zhang, H. et al. High-performance ultraviolet organic light-emitting diode enabled by high-lying reverse intersystem crossing, Angew. Chem. Int. Ed. 60 , 1–8 (2021). Hung, C.-M. et al. High-performance near-infrared OLEDs maximized at 925 nm and 1022 nm through interfacial energy transfer, Nat . Commun . 15 , 4664 (2024) . Wang, J. et al. Promising interlayer sensitization strategy for the construction of high-performance blue hyperfluorescence OLEDs, Light Sci . Appl . 13 , 139 (2024). Liu, H., Fu, Y., Chen, J., Tang, B. Z., & Zhao, Z. et al. Energy-efficient stable hyperfluorescence organic light-emitting diodes with improved color purities and ultrahigh power efficiencies based on low-polar sensitizing systems, Adv. Mater. 2212237 (2023). Huang, M. et al. Harmonization of rapid triplet up-conversion and singlet radiation enables efficient and stable white OLEDs, Nat . Commun . 15 , 8048 (2024). Chan, C.-Y. et al. Stable pure-blue hyperfluorescence organic light-emitting diodes with high-efficiency and narrow emission, Nat . Photon . 15 , 203–205 (2021). Kirch, A. et al. Experimental proof of Joule heating-induced switched-back regions in OLEDs, Light Sci . Appl . 9 , 5 (2020). Fu, Y., Liu, H., Tang, B. Z., & Zhao, Z. Realizing efficient blue and deep-blue delayed fluorescence materials with record-beating electroluminescence efficiencies of 43.4%, Nat . Commun . 14 , 2019 (2023). Liu, D. et al. Highly horizontal oriented tricomponent exciplex host with multiple reverse intersystem crossing channels for high-performance narrowband electroluminescence and eye-protection white organic light-emitting diodes, Adv. Mater. 36 , 2403584 (2024). Park, Y. S. et al. Exciplex-forming co-host for organic light-emitting diodes with ultimate efficiency , Adv. Funct. Mater. 23 , 4914−4920 (2013). Al, Amin N. et al. A comparative study via photophysical and electrical characterizations on interfacial and bulk exciplex-forming systems for efficient organic light-emitting diodes , ACS Applied Electron . Mater . 2 , 1011−1019 (2020). Wang, F J, Bässler, H., & Vardeny, Z V. Magnetic field effects in π-conjugated polymer-fullerene blends: evidence for multiple components, Phys . Rev . Lett. 101 , 236805 (2008). Liu, H., Fu, Y., Tang, B. Z., & Zhao, Z. et al. All-fluorescence white organic light-emitting diodes with record-beating power efficiencies over 130 lm W ‒1 and small roll-offs, Nat. Commun. 13 ,5154(2022). Chan, C.-Y. et al. Stable pure-blue hyperfluorescence organic light-emitting diodes with high-efficiency and narrow emission , Nat. Photon. 15 , 203−207 (2021). Hua, T. et al. Deep-blue organic light-emitting diodes for ultrahigh-definition displays , Nat . Photon . 18 , 1161–1169 (2024). Sun, J. et al. Exceptionally stable blue phosphorescent organic light-emitting diode , Nat. Photon. 16 , 212−218 (2022). Qi, Y. et al. Peripheral decoration of multi-resonance molecules as a versatile approach for simultaneous long-wavelength and narrowband emission, Adv. Funct. Mater. 31 , 2102017 (2021). Liu, J. et al. Toward a BT.2020 green emitter through a combined multiple resonance effect and multi-lock strategy, Nat. Commun. 13 , 4876 (2022). Lu, T. & Chen, F. Multiwfn: A multifunctional wavefunction analyzer, J. Comput. Chem. 33 , 580 (2011). Additional Declarations There is no conflict of interest Supplementary Files Supplementalfiles.docx Supporting information for Ultra-high power efficiency organic light-emitting diodes based on hot-exciton-assisted exciplex (HEAE) system Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6904824","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":478177625,"identity":"5b712c9e-41db-47b5-ac3b-be5e139301c6","order_by":0,"name":"Zhiming Wang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA8UlEQVRIiWNgGAWjYLACxgYJBjYg9QDKNyBaCzNIqQSxWsAUmwRRWgyOnz388ucOi2g+6fZrlT9qDtcxsDdvk2CouYNby5m8NAvJMxK5bTJnym7zHDsswcBzrEyC4dgznFrMDuSYGRi2AbVI5KTdZmwAapHIMZMAMnBrOf/GzCARqqXwJ0iL/BsCWm7kGD84CNaSfoyBF2wLD34t9jfemDE2QmxhluY5li7ZxpNWbJFwDLcWyf4c448/2+py589If/jxR401Pz/74Y03PtTg1sIAjQ4g4IFEBxuISMCnARjpHyA0+wP86kbBKBgFo2DEAgCZUFMTWU4+JQAAAABJRU5ErkJggg==","orcid":"","institution":"South China University of Technology","correspondingAuthor":true,"prefix":"","firstName":"Zhiming","middleName":"","lastName":"Wang","suffix":""},{"id":478177626,"identity":"47e30a68-4555-4d43-8fe9-582daeb4acf8","order_by":1,"name":"Jingli Lou","email":"","orcid":"","institution":"South China University of Technology","correspondingAuthor":false,"prefix":"","firstName":"Jingli","middleName":"","lastName":"Lou","suffix":""},{"id":478177627,"identity":"efd9202b-5115-493b-82e2-27b80487e85a","order_by":2,"name":"Junwei He","email":"","orcid":"","institution":"South China University of Technology","correspondingAuthor":false,"prefix":"","firstName":"Junwei","middleName":"","lastName":"He","suffix":""},{"id":478177628,"identity":"f33cfc8e-ed6f-4222-bad8-ee29cc3548af","order_by":3,"name":"Baoxi Li","email":"","orcid":"","institution":"South China University of Technology","correspondingAuthor":false,"prefix":"","firstName":"Baoxi","middleName":"","lastName":"Li","suffix":""},{"id":478177629,"identity":"5e44829b-414e-4786-9353-f22a39a208d5","order_by":4,"name":"Yichao Chen","email":"","orcid":"","institution":"South China University of Technology","correspondingAuthor":false,"prefix":"","firstName":"Yichao","middleName":"","lastName":"Chen","suffix":""},{"id":478177630,"identity":"b1ea82a0-6049-442c-badb-31e93edc962d","order_by":5,"name":"Han Zhang","email":"","orcid":"","institution":"The Chinese University of Hong Kong Shenzhen (CUHK-Shenzhen)","correspondingAuthor":false,"prefix":"","firstName":"Han","middleName":"","lastName":"Zhang","suffix":""},{"id":478177631,"identity":"c7697bc6-808a-4376-be0d-7cdb01b603ad","order_by":6,"name":"Ben Zhong Tang","email":"","orcid":"","institution":"The Chinese University of Hong Kong","correspondingAuthor":false,"prefix":"","firstName":"Ben","middleName":"Zhong","lastName":"Tang","suffix":""}],"badges":[],"createdAt":"2025-06-16 11:00:39","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6904824/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6904824/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":85885978,"identity":"09c4bc1d-8ec2-4868-9db4-2af48a6602f7","added_by":"auto","created_at":"2025-07-02 17:39:36","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":61666,"visible":true,"origin":"","legend":"\u003cp\u003eThe mechanism of HEAE system and C-type exciplex under the electric field, in which ISC is intersystem crossing, IC is internal conversion, and F is fluorescence.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6904824/v1/1698c24ca699ba0829da0f0f.png"},{"id":85885981,"identity":"8f659e93-3227-4877-8a79-c9aded5beda3","added_by":"auto","created_at":"2025-07-02 17:39:36","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":270150,"visible":true,"origin":"","legend":"\u003cp\u003ePhotophysical properties of exciplexes. aMolecular structures of compounds used in this study. b UV–vis absorption (left), PL spectra (middle), and transient PL decay curves (right) of exciplex films at room temperature. c Energy levels of exciplexes and donors.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6904824/v1/308e0e335cd1aa738675829b.png"},{"id":85885984,"identity":"80c03d8b-8767-4a0e-aa02-0a95c1c2aeb3","added_by":"auto","created_at":"2025-07-02 17:39:36","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":211651,"visible":true,"origin":"","legend":"\u003cp\u003eElectroluminescent performances of exciplexes. a Device structure. b EL spectrum of devices at 10 mA cm\u003csup\u003e−2\u003c/sup\u003e. c EQE–luminance characteristics of devices. d Interactions of donor and acceptor with different numbers of spacers. e EL spectrum at 10 mA cm\u003csup\u003e−2\u003c/sup\u003e. f EQE–current density-PE characteristics.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6904824/v1/0de685c742f02ad415daa523.png"},{"id":85886284,"identity":"2ec8d6aa-4261-4da5-af18-7758cefb557c","added_by":"auto","created_at":"2025-07-02 17:47:36","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":99902,"visible":true,"origin":"","legend":"\u003cp\u003eExciton dynamics and charge carrier evaluations of exciplexes. a MEL curves of devices H1, H2, and H3 at 5 mA cm\u003csup\u003e−2\u003c/sup\u003e. b Election carrier mobilities (μ\u003csub\u003ee\u003c/sub\u003e)-electric field curves of 2MCz-CNMCz, 2t-2MCz-CNMCz, and 4t-2MCz-CNMCz. c PL spectra of H1 film, absorption, and PL spectra of TBRb in toluene solution.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6904824/v1/fecd26ba20efd4bcdbf79ab0.png"},{"id":85885987,"identity":"c4d8512e-1834-4678-bcd7-e73ddec18aee","added_by":"auto","created_at":"2025-07-02 17:39:36","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":180695,"visible":true,"origin":"","legend":"\u003cp\u003eSensitization performance of OLEDs based on the host of exciplex H1. a Mechanism of HESF. b Absorption of four MR-TADF materials in toluene solution and PL spectra of H1 film. c Transient PL lifetime of four sensitized films. d EL spectrum of the devices at 10 mA cm\u003csup\u003e−2\u003c/sup\u003e. e EQE–luminance–PE characteristics. f Summary of emission peak wavelength–PE–EQE of green and orange OLEDs (insert: red star represents devices with PE high than 220 lm W\u003csup\u003e─1\u003c/sup\u003e).\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-6904824/v1/afa211fd68da4c0ef1c8b238.png"},{"id":88843661,"identity":"b5378b50-c489-49dd-822a-40bffa311fde","added_by":"auto","created_at":"2025-08-12 03:23:49","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1647006,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6904824/v1/5251bb3a-af44-4b6d-a3ba-ef511b321b4f.pdf"},{"id":85885996,"identity":"50854486-35ed-42b4-9b53-b3473811ae8c","added_by":"auto","created_at":"2025-07-02 17:39:36","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":10326404,"visible":true,"origin":"","legend":"Supporting information for Ultra-high power efficiency organic light-emitting diodes based on hot-exciton-assisted exciplex (HEAE) system","description":"","filename":"Supplementalfiles.docx","url":"https://assets-eu.researchsquare.com/files/rs-6904824/v1/936b1796b0ae4dc363b4a9c1.docx"}],"financialInterests":"There is no conflict of interest","formattedTitle":"Ultra-high power efficiency organic light-emitting diodes based on hot-exciton-assisted exciplex (HEAE) system","fulltext":[{"header":"Introduction","content":"\u003cp\u003eOrganic light-emitting diodes (OLEDs) are widely used in the fields of display and illumination due to their unique advantages, such as flexibility, high resolution, and low power consumption\u003csup\u003e1,2\u003c/sup\u003e. As the awareness of energy conservation is deeply rooted in individuals, the demands regarding low-power-consumption electronic products are increasing. In general, the power consumption of an OLED is described by power efficiency (PE, \u003cem\u003eη\u003c/em\u003e\u003csub\u003eP\u003c/sub\u003e), which is related to external quantum efficiency (EQE, \u003cem\u003eη\u003c/em\u003e\u003csub\u003eEQE\u003c/sub\u003e), average photon energy (\u003cem\u003eĒ\u003c/em\u003e), and driving voltage (\u003cem\u003eU\u003c/em\u003e).\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$\\:{\\eta\\:}_{P}=\\text{E}\\text{Q}\\text{E}\\bullet\\:\\frac{\\stackrel{-}{E}\\:\\left(eV\\right)}{U\\left(V\\right)}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWith the same \u003cem\u003eĒ\u003c/em\u003e, a higher PE can be obtained by endowing the OLED with a higher EQE and a lower \u003cem\u003eU\u003c/em\u003e. Using the heavy-atom effect or reverse intersystem crossing (RISC) process in a single molecule, a maximum EQE of 20\u0026ndash;40% can be realized. Nevertheless, simultaneously achieving a low \u003cem\u003eU\u003c/em\u003e is difficult for a single molecule due to the energy level barriers usually exist between the emitting materials layer (EML) and adjacent functional layers, resulting in a \u003cem\u003eU\u003c/em\u003e exceeding the bandgaps of emitters. Therefore, the OLEDs with PE\u0026thinsp;\u0026ge;\u0026thinsp;200 lm W\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e are still rare.\u003c/p\u003e \u003cp\u003eOther than the donor and acceptor concentrated within a single molecule, the luminescent system where donor and acceptor are distributed on different molecules, respectively, commonly referred to as an exciplex, has also realized high EQE through the RISC process driven by an intermolecular charge transfer (CT) interaction\u003csup\u003e3\u003c/sup\u003e. Typically, the donor molecule in the exciplex system (donor for short) is hole-dominant, and the acceptor molecule in the exciplex system (acceptor for short) is electron-dominant, resulting in a low energy level barrier with adjacent layers. Hence, exciplex is an ideal candidate to match the demand for high-PE OLED\u003csup\u003e4,5\u003c/sup\u003e. However, the slow RISC process of conventional exciplex generally causes severe exciton quenching and a low exciton utilization\u003csup\u003e6\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eTo address this, various strategies have been proposed to enhance the exciton utilization of exciplex. Although the RISC process in exciplex systems composed of conventional material (C-type exciplex) can be accelerated via spin\u0026ndash;orbit coupling (SOC) effect, this requires the locally excited triplet states (\u0026sup3;LE) of the donor or acceptor strictly limited adjacent to the CT-dominated singlet (\u003csup\u003e1\u003c/sup\u003eCT) and triplet (\u0026sup3;CT) states\u003csup\u003e7\u0026ndash;9\u003c/sup\u003e. Recently, introducing additional RISC channels has become another way to improve exciton utilization of exciplex by recovering excitons recombined at the donors or acceptors\u003csup\u003e10\u003c/sup\u003e. For example, Zhang et al. applied a thermally activated delayed fluorescence (TADF) material named MAC as the donor of exciplexes, preparing OLEDs with high efficiency and low-efficiency roll-off\u003csup\u003e11\u003c/sup\u003e. Moreover, featuring low-lying \u003csup\u003e3\u003c/sup\u003eLE states and rapid high-lying RISC channels, hot-exciton materials are ideal candidates for assisting exciplex from both the SOC effect and additional RISC channels. Unfortunately, only a few exciplex systems containing hot-exciton materials (H-type exciplex) have been reported; however, a comprehensive investigation is rarely explored to explain the underlying mechanisms\u003csup\u003e12,13\u003c/sup\u003e. And we note that hot-exciton materials were used as acceptors for exciplex and have not yet been used as donors. In addition, the conventional donor and acceptor materials usually feature extremely unipolar transport, impeding carrier transfer between donor and donor or acceptor and acceptor in exciplex. Although resolving this issue is essential for facilitating carrier injection and promoting exciton recombination, it has received little attention.\u003c/p\u003e \u003cp\u003eHerein, we developed a hot-exciton-assisted exciplex (HEAE) system, which exhibited high exciton utilization, barrier-free carrier injection, and a wide exciton recombination area in electroluminescence (EL). Three hot-exciton materials\u0026mdash;2MCz-CNMCz, 2\u003cem\u003et\u003c/em\u003e-2MCz-CNMCz, and 4\u003cem\u003et\u003c/em\u003e-2MCz-CNMCz\u0026mdash;were used as donors\u0026mdash;combined with 2,4,6-tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine (PO-T2T) to construct exciplexes H1, H2, and H3, respectively. Owing to the low-lying \u003csup\u003e3\u003c/sup\u003eLE states and the high-lying RISC channels of the three hot-exciton materials, the RISC process was accelerated by the SOC effect under an electric field, and effective exciton utilization was achieved through the F\u0026ouml;rster resonance energy transfer (FRET) process (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Consequently, OLEDs based on H1 showed green emissions with twice the maximum external quantum efficiency (EQE) of C-type exciplexes. Introducing a third component to fine-tune the horizontal dipole orientation (\u003cem\u003eΘ\u003c/em\u003e\u003csub\u003e∥\u003c/sub\u003e) of H1, the maximum EQE and PE were enhanced to 19.0% and 82.1 lm W\u003csup\u003e─1\u003c/sup\u003e, respectively. Magneto-EL (MEL) curves demonstrated that the RISC originated from the SOC effect and was regulated via peripheral \u003cem\u003etert\u003c/em\u003e-butyl groups on the hot-exciton materials. Detection of exciton recombination regions in H1-based OLED confirmed a wide exciton recombination area of exciplex H1. Therefore, exciplex H1 was applied as a sensitized host of four multiple-resonance TADF (MR-TADF) emitters. As a result, four sensitized devices with maximum EQEs of 37.7%, 40.5%, 30.7%, and 33.4% and PEs of 232.8, 223.5, 176.6, and 203.6 lm W\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e were designed, respectively. These results confirm efficient conversion of electrically generated excitons into luminescence in the HEAE system, providing an effective method for obtaining OLEDs with high PE.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003ePhotophysical properties\u003c/h2\u003e \u003cp\u003eBlue-violet materials with high T\u003csub\u003e1\u003c/sub\u003e levels are commonly selected as donors or acceptors to prevent back energy transfer, in which carbazole derivatives featuring wide bandgaps, excellent hole transport, and molecular planarity are ideal candidates\u003csup\u003e14\u003c/sup\u003e. The reported hot-exciton carbazole derivative 2MCz-CNMCz, with a high T\u003csub\u003e1\u003c/sub\u003e energy of 2.69 eV, high hole mobility of 2.8 \u0026times; 10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e cm\u003csup\u003e2\u003c/sup\u003e V\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and exciton utilization rate of 77.1%, is chosen as the donor\u003csup\u003e15\u003c/sup\u003e. Different quantities of \u003cem\u003etert\u003c/em\u003e-butyl groups are introduced into 2MCz-CNMCz, expecting to regulate the SOC effect in the exciplex. Here, two tailor-made molecules, 2\u003cem\u003et\u003c/em\u003e-2MCz-CNMCz and 4\u003cem\u003et\u003c/em\u003e-2MCz-CNMCz, are designed and evaluated. Their specific synthesis routes are described in the Supporting Information.\u003c/p\u003e \u003cp\u003eThe photoluminescence (PL) properties of 2\u003cem\u003et\u003c/em\u003e-2MCz-CNMCz and 4\u003cem\u003et\u003c/em\u003e-2MCz-CNMCz were evaluated (Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e and Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e\u0026ndash;S3). Based on the onset energies of the fluorescence and phosphorescence spectra at 77 K in toluene, the S\u003csub\u003e1\u003c/sub\u003e and T\u003csub\u003e1\u003c/sub\u003e energy levels are estimated to be 3.29 and 2.68 eV for 2\u003cem\u003et\u003c/em\u003e-2MCz-CNMCz and 3.32 and 2.77 eV for 4\u003cem\u003et\u003c/em\u003e-2MCz-CNMCz, corresponding to large energy gap (Δ\u003cem\u003eE\u003c/em\u003e\u003csub\u003eS1\u0026ndash;T1\u003c/sub\u003e) values of 0.61 and 0.55 eV, respectively. Compared to 2MCz-CNMCz, the introduction of \u003cem\u003etert\u003c/em\u003e-butyl into 2\u003cem\u003et\u003c/em\u003e-2MCz-CNMCz and 4\u003cem\u003et\u003c/em\u003e-2MCz-CNMCz has minimal effects on the PL properties, and the large Δ\u003cem\u003eE\u003c/em\u003e\u003csub\u003eS1\u0026ndash;T1\u003c/sub\u003e excludes the TADF mechanism. Natural transition orbital simulation confirmed that the T\u003csub\u003e1\u003c/sub\u003e states of both 2\u003cem\u003et\u003c/em\u003e-2MCz-CNMCz and 4\u003cem\u003et\u003c/em\u003e-2MCz-CNMC are LE-dominated (Fig. S2 and Table S4\u0026ndash;S5). Based on the energy level distributions of singlet and triplet states, hot-exciton channels are presumed to exist in both molecules (Fig. S3)\u003csup\u003e16\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eHerein, three hot-exciton molecules\u0026mdash;2MCz-CNMCz, 2\u003cem\u003et\u003c/em\u003e-2MCz-CNMCz, and 4\u003cem\u003et\u003c/em\u003e-2MCz-CNMCz\u0026mdash;are employed as donors to form exciplexes with the high-triplet (T\u003csub\u003e1\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;3.0 eV) materials PO-T2T as the acceptor, yielding H1, H2, and H3, respectively. The HOMO and LUMO energy levels of the 2MCz-CNMCz, 2\u003cem\u003et\u003c/em\u003e-2MCz-CNMCz, and 4\u003cem\u003et\u003c/em\u003e-2MCz-CNMCz are \u0026minus;\u0026thinsp;5.35 and \u0026minus;\u0026thinsp;2.28 eV, \u0026minus;\u0026thinsp;5.53 and \u0026minus;\u0026thinsp;2.24 eV, and \u0026minus;\u0026thinsp;5.54 and \u0026minus;\u0026thinsp;2.24 eV, respectively, matching with the HOMO (\u0026minus;\u0026thinsp;7.5 eV) and LUMO (\u0026minus;\u0026thinsp;3.5 eV) of PO-T2T (Fig. S4)\u003csup\u003e17\u003c/sup\u003e. To enable a systematic investigation of the proposed concept, five conventional donors\u0026mdash;including carbazole and triphenylamine derivatives (mcp, \u003cem\u003em\u003c/em\u003eCBP, TcTa, TAPC, and Tris-PCz) \u0026mdash;are also selected to form exciplexes with PO-T2T in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, named C1, C2, C3, C4, and C5, respectively\u003csup\u003e18\u0026ndash;22\u003c/sup\u003e. The PL properties of all donor\u0026ndash;acceptor mixtures were evaluated in films using an optimized ratio of 40 wt% donor to 60 wt% acceptor. All mixtures showed broad absorption tails extending to 600 nm, attributed to intermolecular CT transitions. Mixtures H1, H2, and H3 exhibited green emission, clearly distinct from the spectra of either donor or PO-T2T (Fig. S5), confirming the formation of exciplex. Transient PL decay curves for H1, H2, and H3 revealed typical biexponential decay profiles comprising prompt (\u003cem\u003eτ\u003c/em\u003e\u003csub\u003eP\u003c/sub\u003e) and delayed (\u003cem\u003eτ\u003c/em\u003e\u003csub\u003eD\u003c/sub\u003e) components, further confirming exciplex generation. The photoluminescence quantum yield (PLQY) values of exciplexes H1, H2, and H3 were 37.4%, 44.9%, and 38.8%, respectively.\u003c/p\u003e \u003cp\u003eWhen the temperature dropped to 77 K, all H-type and C-type exciplexes showed long-lived phosphorescence emissions (Fig. S6). As shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, three H-type exciplexes showed Δ\u003cem\u003eE\u003c/em\u003e\u003csub\u003eS1\u0026ndash;T1\u003c/sub\u003e values of 0.23, 0.26, and 0.27 eV, respectively, while the Δ\u003cem\u003eE\u003c/em\u003e\u003csub\u003eS1\u0026ndash;T1\u003c/sub\u003es of five C-type exciplexes were almost zero. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec, the energy levels of \u003csup\u003e3\u003c/sup\u003eLE states of hot-exciton materials are located between the \u003csup\u003e1\u003c/sup\u003eCT and \u003csup\u003e3\u003c/sup\u003eCT states of exciplexes. It is speculated that the SOC effect between the \u003csup\u003e3\u003c/sup\u003eLE and CT states promotes the spin-mixing between \u003csup\u003e1\u003c/sup\u003eCT and \u003csup\u003e3\u003c/sup\u003eCT states. Moreover, the high-lying RISC process in hot-exciton materials is expected to recover exciton energy for exciplexes. However, the \u003cem\u003ek\u003c/em\u003e\u003csub\u003eRISC\u003c/sub\u003e values evaluated by transient PL decay curves for the H1, H2, and H3 exciplexes were 1.5 \u0026times; 10\u003csup\u003e5\u003c/sup\u003e, 1.8 \u0026times; 10\u003csup\u003e5\u003c/sup\u003e, and 1.0 \u0026times; 10\u003csup\u003e5\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively, suggesting slow RISC processes in PL. By contrast, the \u003cem\u003ek\u003c/em\u003e\u003csub\u003eRISC\u003c/sub\u003e values of C-type exciplexes evaluated by the transient PL decay curves ranged from 2.0\u0026thinsp;~\u0026thinsp;4.4 \u0026times; 10\u003csup\u003e6\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Fig. S7).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePhotophysical characteristics of exciplex films.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"12\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExciplex\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eλ\u003c/em\u003e\u003csub\u003eabs\u003c/sub\u003e\u003csup\u003ea\u003c/sup\u003e (nm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eλ\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e\u003csup\u003ea\u003c/sup\u003e (nm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePLQY\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eτ\u003c/em\u003e\u003csub\u003eP\u003c/sub\u003e\u003csup\u003eb\u003c/sup\u003e (ns)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003eτ\u003c/em\u003e\u003csub\u003eD\u003c/sub\u003e\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e(\u0026micro;s)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csub\u003edelayed\u003c/sub\u003e\u003csup\u003ec\u003c/sup\u003e (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cem\u003ek\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e(\u0026times; 10\u003csup\u003e6\u003c/sup\u003e s\u003csup\u003e‒1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u003cem\u003ek\u003c/em\u003e\u003csub\u003eIC\u003c/sub\u003e\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e(\u0026times; 10\u003csup\u003e6\u003c/sup\u003e s\u003csup\u003e‒1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003e\u003cem\u003ek\u003c/em\u003e\u003csub\u003eISC\u003c/sub\u003e\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e(\u0026times; 10\u003csup\u003e7\u003c/sup\u003e s\u003csup\u003e‒1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003e\u003cem\u003ek\u003c/em\u003e\u003csub\u003eRISC\u003c/sub\u003e\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e(\u0026times; 10\u003csup\u003e6\u003c/sup\u003e s\u003csup\u003e‒1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c12\"\u003e \u003cp\u003e\u003cem\u003eE\u003c/em\u003e\u003csub\u003eS1\u003c/sub\u003e/\u003cem\u003eE\u003c/em\u003e\u003csub\u003eT1\u003c/sub\u003e/\u003c/p\u003e \u003cp\u003eΔ\u003cem\u003eE\u003c/em\u003e\u003csub\u003eS1T1\u003c/sub\u003e\u003csup\u003ed\u003c/sup\u003e (eV)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eH1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e352\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e521\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e37.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e16.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e33.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e79.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e7.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e4.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e2.68 /2.45/0.23\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eH2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e354\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e514\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e44.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e22.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e140.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e91.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e4.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e2.76 /2.50/0.26\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eH3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e352\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e507\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e38.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e22.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e160.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e90.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e2.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e4.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e2.80 /2.53/0.27\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e328\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e475\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e39.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e44.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e88.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e1.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e2.92/2.87/0.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e343\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e476\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e39.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e43.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e87.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e1.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e2.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e2.92/2.92/0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e335\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e542\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e20.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e55.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e72.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e4.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e1.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e4.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e2.58/2.57/0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e282\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e562\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e13.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e59.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e84.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e2.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e1.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e3.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e2.48/2.46/0.02\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e309\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e535\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e12.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e47.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e82.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e3.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e1.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e4.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e2.57/2.57/0.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003csup\u003ea\u003c/sup\u003eThe characteristic absorption peaks, emission peaks, and photoluminescence quantum yield (PLQY) in nitrogen environment of exciplex films.\u003c/p\u003e \u003cp\u003e \u003csup\u003eb\u003c/sup\u003eFitting from the transient PL decay curves of exciplex film.\u003c/p\u003e \u003cp\u003e \u003csup\u003ec\u003c/sup\u003eDeduced from the PLQY and transient PL decay curves.\u003c/p\u003e \u003cp\u003e \u003csup\u003ed\u003c/sup\u003eDetermined from the onset of PL and phosphorescence spectra in film at 77K.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eElectroluminescent performance\u003c/h3\u003e\n\u003cp\u003eOLEDs with different EMLs were designed and fabricated with the structures shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e: ITO (90 nm)/HATCN (5 nm)/TAPC (50 nm)/TcTa (5 nm)/EML (20 nm)/PO-T2T (50 nm)/LiF (1 nm)/Al (120 nm), where HATCN, TAPC, and TcTa are 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile, 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane, and tris(4-(9H-carbazol-9-yl)phenyl)amine, respectively. The EMLs included H-type exciplexes (devices H1, H2, and H3) and C-type exciplexes (devices C1, C2, C3, C4, and C5). The device H1\u0026ndash;H3 showed low turn-on voltages (\u003cem\u003eV\u003c/em\u003e\u003csub\u003eon\u003c/sub\u003e) of 2.2, 2.2, and 2.3 V, and the device C1\u0026ndash;C5 showed \u003cem\u003eV\u003c/em\u003e\u003csub\u003eon\u003c/sub\u003es of 2.8, 2.4, 2.2, 2.2, and 2.2 V. As shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, the \u003cem\u003eV\u003c/em\u003e\u003csub\u003eon\u003c/sub\u003e values of device H1\u0026ndash;H3 were lower than their photon energy of wavelength peak of EL spectra (\u003cem\u003eE\u003c/em\u003e\u003csub\u003eλ\u003c/sub\u003e), while the \u003cem\u003eV\u003c/em\u003e\u003csub\u003eon\u003c/sub\u003e of devices C1\u0026ndash;C5 were higher than or close their \u003cem\u003eE\u003c/em\u003e\u003csub\u003eλ\u003c/sub\u003e values, indicating H-type exciplexes achieved a better carrier injection than C-type exciplexes. Devices H1, H2, and H3 exhibited green emission with peak emission wavelengths (\u003cem\u003eλ\u003c/em\u003e\u003csub\u003eEL\u003c/sub\u003e) of 532, 532, and 526 nm, respectively, and maximum EQEs of 13.5%, 11.6%, and 10.0%. For devices C1\u0026ndash;C5, the \u003cem\u003eλ\u003c/em\u003e\u003csub\u003eEL\u003c/sub\u003e values were 528, 528, 546, 572, and 560 nm, and the maximum EQEs were 6.9%, 5.7%, 7.4%, 4.3%, and 6.3%, respectively. Notably, H-type exciplexes demonstrated maximum EQEs 2\u0026ndash;3 times higher than those of devices C1\u0026ndash;C5. This improvement is attributed to the hot-exciton channels in the donor materials, which help recover exciton energy captured by the donor molecules. In addition, improving the \u003cem\u003eΘ\u003c/em\u003e\u003csub\u003e∥\u003c/sub\u003e of exciplexes has proved to boost the optical outcoupling efficiency (\u003cem\u003eη\u003c/em\u003e\u003csub\u003eout\u003c/sub\u003e) of devices\u003csup\u003e23,24\u003c/sup\u003e. By incorporating an inert materials DPEPO ([2-(diphenylphosphino)phenyl]ether oxide) as spacer into exciplex H1 at different ratios, the \u003cem\u003eΘ\u003c/em\u003e\u003csub\u003e∥\u003c/sub\u003e of H1 improved from 54.6\u0026ndash;66.7%, resulting in a substantial increase in \u003cem\u003eη\u003c/em\u003e\u003csub\u003eout\u003c/sub\u003e from 25.8\u0026ndash;34.3% (Fig. S8 and Table S6). However, the incorporation of spacers also impeded the carrier transport in EML and increased the \u003cem\u003eV\u003c/em\u003e\u003csub\u003eon\u003c/sub\u003e of devices. Consequently, device D1 with moderate spacers (EML composed of 50 wt% exciplex H1 and 50 wt% DPEPO) maintained a green emission (\u003cem\u003eλ\u003c/em\u003e\u003csub\u003eEL\u003c/sub\u003e of 526 nm) and achieved a maximum EQE of 19.0% and PE of 82.1 lm W\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eExciton dynamics and charge carrier\u003c/h3\u003e\n\u003cp\u003eTo explore the effect of introducing \u003cem\u003etert-\u003c/em\u003ebutyl on exciton dynamics in H-type exciplexes, the magnetic field effects at different current densities were measured (Fig. S9 and Table S7). As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea, under the external magnetic field, the MEL line shapes of devices H1, H2, and H3 increased continuously. The maximum half-widths of the MEL curves of devices H1, H2, and H3 were larger than those caused by hyperfine interaction (HFI) (\u0026lt;\u0026thinsp;10 mT), indicating that the magnetic field effect was governed by the SOC effect and derived from the low-lying \u003csup\u003e3\u003c/sup\u003eLE state of the hot-exciton materials and the CT states of the exciplexes\u003csup\u003e9,25,26\u003c/sup\u003e. The MEL curves at different current densities were fitted by the Δ\u003cem\u003eg\u003c/em\u003e factor model, and the fitted curves were completely consistent with the data obtained from the measurement\u003csup\u003e27\u003c/sup\u003e. The fitting constant (\u003cem\u003eC\u003c/em\u003e) values of devices H1 to H3 were 0.135, 0.122, and 0.100, respectively, suggesting an increased SOC effect. Herein, the effect of SOC in exciplex was effectively regulated by introducing \u003cem\u003etert\u003c/em\u003e-butyl groups in donors.\u003c/p\u003e \u003cp\u003eThe excellent carrier injection in devices H1, H2, and H3 was further investigated by fabricating electron-only devices (EODs) and hole-only devices (HODs) of 2MCz-CNMCz, 2\u003cem\u003et\u003c/em\u003e-2MCz-CNMCz, and 4\u003cem\u003et\u003c/em\u003e-2MCz-CNMCz. The three molecules not only exhibited high hole carrier mobilities (\u003cem\u003e\u0026micro;\u003c/em\u003e\u003csub\u003eh\u003c/sub\u003e) at the magnitude of 10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e cm\u003csup\u003e2\u003c/sup\u003e V\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Table S8), but also exhibited well electron carrier mobilities (\u003cem\u003e\u0026micro;\u003c/em\u003e\u003csub\u003ee\u003c/sub\u003e) at the magnitude of 10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e cm\u003csup\u003e2\u003c/sup\u003e V\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb), which were different from the conventional donors featuring unipolar transport properties. Consequently, three H-type exciplexes demonstrated \u003cem\u003eV\u003c/em\u003e\u003csub\u003eon\u003c/sub\u003es lower than their \u003cem\u003eE\u003c/em\u003e\u003csub\u003eλ\u003c/sub\u003e, achieving a barrier-free carrier injection. Furthermore, an orange fluorescence emitter, 2,8-di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyltetracene (TBRb), was used as a detector to study carrier recombination in device H1\u003csup\u003e28\u003c/sup\u003e. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec, the absorption spectrum of TBRb closely overlapped with the PL spectrum of H1 exciplex, indicating efficient FRET from H1 to TBRb. An ultrathin (0.2 nm) layer of TBRb was inserted into the EML of device H1 at various positions, and the relative emission intensity of TBRb was recorded to plot the relative intensity\u0026ndash;position\u0026ndash;voltage graph. The relative emission intensity of TBRb was evenly distributed across the entire EML during different operation voltages, demonstrating a wide and evenly distributed exciton recombination area within the exciplex H1 (Fig. S10).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eSensitization performance\u003c/h3\u003e\n\u003cp\u003eOwing to the efficient exciton utilization, excellent carrier injection, and wide exciton recombination area, exciplex H1 was an ideal candidate for sensitized hosts. MR-TADF emitters with narrow full-width at half maximum (FWHM) show great potential for ultrahigh-definition OLED displays\u003csup\u003e29\u003c/sup\u003e. However, the slow RISC process hindered the development of MR-TADF\u003csup\u003e30\u003c/sup\u003e. Sensitized emission, which uses MR-TADF as the terminal emitter and materials with a high exciton utilization as sensitizers, enabled the OLEDs with both ultrahigh PE and narrow emission by transferring energy from the sensitizers to the emitter\u003csup\u003e31\u003c/sup\u003e. Herein, the HEAE sensitized fluorescence (HESF) concept was proposed, which includes the HEAE system as a host and a fluorescent dopant. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, energy is transferred from the HEAE system to the dopants via FRET, using a low dopant concentration of 1 wt% to avoid Dexter energy transfer (DET).\u003c/p\u003e \u003cp\u003eFour MR-TADF materials with high PLQYs and narrow-emission spectra\u0026mdash;BN2, BN3, tCzphB-Ph, and tCzphB-Fl\u0026mdash;were doped into H1 as terminal emitters\u003csup\u003e32,33\u003c/sup\u003e. The absorption bands of four dopants overlapped with the PL emission of H1, and the sensitized films exhibited \u003cem\u003eλ\u003c/em\u003e\u003csub\u003eEL\u003c/sub\u003e values at 543, 565, 525, and 537 nm with FWHM values of 43, 40, 30, and 31 nm, respectively (Fig. S11). As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb, the energy transfer processes in sensitized films were investigated through transient PL measurements, revealing a reduction in delayed lifetime and corresponding \u003cem\u003ek\u003c/em\u003e\u003csub\u003eRISC\u003c/sub\u003e rates of 1.1 \u0026times; 10\u003csup\u003e6\u003c/sup\u003e, 3.0 \u0026times; 10\u003csup\u003e6\u003c/sup\u003e, 1.1 \u0026times; 10\u003csup\u003e6\u003c/sup\u003e, and 5.5 \u0026times; 10\u003csup\u003e6\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for BN2, BN3, tCzphB-Ph, and tCzphB-Fl, respectively, indicating efficient FRET from H1 to the dopants. Devices were fabricated with the same configuration above, using EMLs of H1: 1 wt% BN2 (device S1), H1: 1 wt% BN3 (device S2), H1: 1 wt% tCzphB-Ph (device S3), and H1: 1 wt% tCzphB-Fl (device S4). As shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, the \u003cem\u003eV\u003c/em\u003e\u003csub\u003eon\u003c/sub\u003e values of devices S1\u0026ndash;S4 were 2.1, 2.1, 2.2, and 2.2 V, which were lower than their \u003cem\u003eE\u003c/em\u003e\u003csub\u003eλ\u003c/sub\u003e values, respectively. Devices S1\u0026ndash;S4 exhibited single peaks at \u003cem\u003eλ\u003c/em\u003e\u003csub\u003eEL\u003c/sub\u003e of 544, 568, 526, and 534 nm with narrow FWHM values of 46, 42, 33, and 33 nm, respectively. Devices S1\u0026ndash;S4 achieved excellent maximum EQEs of 37.7%, 40.5%, 30.7%, and 33.4% and record-breaking PE values of 232.8, 223.5, 176.6, and 203.6 lm W\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively (Table S9). Such low-\u003cem\u003eV\u003c/em\u003e\u003csub\u003eon\u003c/sub\u003es and high-efficiencies should be ascribed to the barrier-free injection and excellent exciton utilization on the HEAE system, showing the advantages of this strategy.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDevice performance of OLEDs.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDevice\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eλ\u003c/em\u003e\u003csub\u003eEL\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e(nm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eE\u003c/em\u003e\u003csub\u003eλ\u003c/sub\u003e \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e(eV)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eV\u003c/em\u003e\u003csub\u003eon\u003c/sub\u003e\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e(V)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eL\u003c/em\u003e\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e(cd m\u003csup\u003e─2\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCE\u003csub\u003emax\u003c/sub\u003e\u003csup\u003ed\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e(cd A\u003csup\u003e─1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003ePE\u003csub\u003emax\u003c/sub\u003e \u003csup\u003ee\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e(lm W\u003csup\u003e─1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eEQE\u003csub\u003emax\u003c/sub\u003e\u003csup\u003ef\u003c/sup\u003e (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eCIE (x, y)\u003csup\u003eg\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eH1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e532\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6632\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e45.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e64.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e13.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.341, 0.576\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eH2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e532\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4611\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e38.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e52.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e11.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.340, 0.572\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eH3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e526\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4275\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e31.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e43.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e10.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.300, 0.549\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e528\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7859\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e22.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e25.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e6.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.310, 0.524\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e528\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7665\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e18.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e20.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e5.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.318, 0.533\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e546\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e27460\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e24.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e30.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e7.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.402, 0.566\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e572\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e13210\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e11.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e13.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.495, 0.497\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e560\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e26630\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e18.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e23.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e6.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.447, 0.534\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eD0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e528\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5168\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e57.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e78.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e17.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.325, 0.566\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eD1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e526\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4172\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e60.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e82.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e19.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.305, 0.556\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eD2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e522\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3331\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e52.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e66.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e16.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.297, 0.542\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eS1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e544\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e20620\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e155.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e232.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e37.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.336, 0.638\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eS2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e568\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e26430\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e149.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e223.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e40.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.464, 0.529\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eS3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e526\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e19680\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e123.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e176.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e30.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.237, 0.703\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eS4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e534\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e19160\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e142.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e203.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e33.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.279, 0.682\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003csup\u003ea\u003c/sup\u003ePhoton energy of wavelength peak of EL spectrum.\u003c/p\u003e \u003cp\u003e \u003csup\u003eb\u003c/sup\u003eTurn-on voltage\u0026thinsp;\u0026ge;\u0026thinsp;1 cd m\u003csup\u003e─2\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003e \u003csup\u003ec\u003c/sup\u003eMaximum luminance.\u003c/p\u003e \u003cp\u003e \u003csup\u003ed\u003c/sup\u003eMaximum current efficiency.\u003c/p\u003e \u003cp\u003e \u003csup\u003ee\u003c/sup\u003eMaximum PE.\u003c/p\u003e \u003cp\u003e \u003csup\u003ef\u003c/sup\u003eMaximum EQE.\u003c/p\u003e \u003cp\u003e \u003csup\u003eg\u003c/sup\u003eCommission internationale de l'\u0026eacute;clairage, recorded at 10 mA cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eHerein, hot-exciton materials featuring low-lying LE-dominated T\u003csub\u003e1\u003c/sub\u003e states and fast high-lying RISC channels were proved as excellent candidates for high-performance exciplexes. And we revealed the underlying mechanism that RISC-acceleration and exciton-recovery effects of hot-exciton materials in HEAE systems. As a result, the exciplex H1 demonstrated a maximum EQE of 19.0% and PE of 82.1 lm W\u003csup\u003e─1\u003c/sup\u003e, double that of the C-type exciplex. In addition, the method of regulating the SOC interactions of exciplexes was offered by introducing \u003cem\u003etert\u003c/em\u003e-butyl groups into the donor material, and the barrier-free injection and wide exciton recombination area of the HEAE system were demonstrated. Considering the commercial demand for narrow emission, four sensitized devices were successfully prepared and obtained unexpected efficiencies, further validating the applicability of the HEAE strategy. Thus, we proved a new strategy for achieving both narrow emission and high PE, surpassing previous performance records, providing valuable insights into the rational design for low-power-consumption OLEDs.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cp\u003e\u003cstrong\u003eGeneral information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll chemicals and reagents were purchased from commercial sources and used as received. The final product underwent vacuum sublimation to improve purity before measuring its PL and EL properties.\u0026nbsp;\u003csup\u003e1\u003c/sup\u003eH and\u0026nbsp;\u003csup\u003e13\u003c/sup\u003eC NMR spectra were recorded on a Bruker AV 500 spectrometer in CD\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e at room temperature. High-resolution mass spectroscopy was performed on a GCT premier CAB048 mass spectrometer operating in MALDITOF mode.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eComputational methods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll density functional theory (DFT) calculations were performed using the Gaussian 16 package. The optimized S\u003csub\u003e0\u003c/sub\u003e geometry and single-point properties at S\u003csub\u003e0\u003c/sub\u003e were calculated using the DFT method at the M06-2X/6-31G (d,p) level\u003csup\u003e34\u003c/sup\u003e. The S\u003csub\u003e1\u003c/sub\u003e geometry was optimized using time-dependent DFT (TD-DFT) at the M06-2X/6-31G (d,p) level. NTO and energy levels of the first five S\u003csub\u003e1\u003c/sub\u003e and T\u003csub\u003e1\u003c/sub\u003e states were calculated based on the S\u003csub\u003e1\u003c/sub\u003e geometry at the M06-2X/6-31G(d,p) level to understand the excited-state properties.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePhotophysical property measurements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSolutions with a concentration of 1 \u0026times; 10\u003csup\u003e\u0026minus;5\u003c/sup\u003e M were prepared for the solution measurements. All organic films used for the PL measurements were deposited onto clean quartz substrates via thermal evaporation at 1\u0026ndash;1.5 \u0026Aring; s\u003csup\u003e\u0026minus;1\u003c/sup\u003e under high vacuum with a base pressure of \u0026lt; 10\u003csup\u003e\u0026minus;5\u003c/sup\u003e torr. Ultraviolet\u0026ndash;visible (UV\u0026ndash;vis) absorption spectra were measured on a Shimadzu UV-2600 spectrophotometer. PL spectra were recorded on a Horiba Fluoromax-4 spectrofluorometer. PLQYs were measured using a Hamamatsu absolute PL quantum yield spectrometer (C11347 Quantaurus_QY). Transient PL decay curves were measured using an Edinburgh Instrument FLS1000 spectrometer.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eElectrochemical and thermal stability measurements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCyclic voltammetry was conducted on a CHI 610E A14297 using a solution of tetra-\u003cem\u003en\u003c/em\u003e-butylammonium hexafluorophosphate (Bu\u003csub\u003e4\u003c/sub\u003eNPF\u003csub\u003e6\u003c/sub\u003e) (0.1 M) in dichloromethane or dimethylformamide at a scan rate of 100 mV s\u003csup\u003e\u0026minus;1\u003c/sup\u003e. A platinum wire was used as the auxiliary electrode, a glass carbon disk as the working electrode, and Ag/Ag\u003csup\u003e+\u003c/sup\u003e as the reference electrode, with the redox couple ferricenium/ferrocene (Fc/Fc\u003csup\u003e+\u003c/sup\u003e) serving as the calibration standard. The ionization potential (IP\u003csub\u003eCV\u003c/sub\u003e) and electron affinities (EA\u003csub\u003eCV\u003c/sub\u003e) of these molecules were calculated using the following formulas: IP\u003csub\u003eCV\u003c/sub\u003e = (\u003cem\u003eE\u003c/em\u003e\u003csub\u003eox\u003c/sub\u003e \u0026minus; \u003cem\u003eE\u003c/em\u003e\u003csub\u003e1/2\u003c/sub\u003e(Fc/Fc\u003csup\u003e+\u003c/sup\u003e) + 4.8) eV and EA\u003csub\u003eCV\u003c/sub\u003e = (\u003cem\u003eE\u003c/em\u003e\u003csub\u003ered\u003c/sub\u003e \u0026minus; \u003cem\u003eE\u003c/em\u003e\u003csub\u003e1/2\u003c/sub\u003e(Fc/Fc\u003csup\u003e+\u003c/sup\u003e) + 4.8) eV, where\u0026nbsp;\u003cem\u003eE\u003c/em\u003e\u003csub\u003eox\u003c/sub\u003e and\u0026nbsp;\u003cem\u003eE\u003c/em\u003e\u003csub\u003ered\u003c/sub\u003e represent the onset oxidation potential and reduction potential relative to Fc/Fc\u003csup\u003e+\u003c/sup\u003e (4.8 eV), respectively.\u0026nbsp;Thermogravimetric analysis was performed on\u0026nbsp;a\u0026nbsp;Netzsch TG 209 under nitrogen flow at a heating rate of 10\u0026deg;C min\u003csup\u003e\u0026minus;\u003c/sup\u003e\u003csup\u003e1\u003c/sup\u003e. Differential scanning calorimetric (DSC) was performed on\u0026nbsp;a\u0026nbsp;Netzsch DSC 200 F3 under nitrogen flow at a heating rate of 10\u0026deg;C min\u003csup\u003e\u0026minus;\u003c/sup\u003e\u003csup\u003e1\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eOLED fabrication and characterization\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe glass substrates, precoated with a 90 nm layer of ITO with a sheet resistance of 15 to 20 ohms per square, were successively cleaned in ultrasonic bath of acetone, isopropanol, detergent, and deionized water, respectively, with each step lasting 10 min. Then, the substrates were completely dried in a 70\u0026deg;C oven. To improve the hole injection ability of ITO, the substrates underwent O\u003csub\u003e2\u003c/sub\u003e plasma treatment for 6 min before fabrication. The vacuum-deposited OLEDs were fabricated under a pressure of \u0026lt; 5 \u0026times; 10\u003csup\u003e\u0026minus;4\u003c/sup\u003e Pa in the Suzhou Fangsheng FS-380 vacuum deposition system. Organic materials, LiF, and Al were deposited at rates of 0.5 to 1.5 A, 0.1, and 3 A s\u003csup\u003e\u0026minus;1\u003c/sup\u003e, respectively. The effective emitting area of the device was 9 mm\u003csup\u003e2\u003c/sup\u003e, determined by the overlap between the anode and cathode. EL spectra, luminance‒voltage‒current density, and EQE were characterized with a dual-channel Keithley 2400 source meter and a PR-670 spectrometer. All characterizations were conducted at room temperature and in ambient conditions without encapsulation, immediately after fabrication.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eD\u003c/strong\u003e\u003cstrong\u003eata availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data that support the findings of this study are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe are grateful for financial support from the National Natural Science Foundation of China (52473173), Natural Science Foundation of Guangdong Province (2022B1515020084), Guangdong Basic and Applied Basic Research Foundation (2023B1515040003), Key Project of Yunnan Provincial Department of Science and Technology (202303AC100021), Independent Research Project of State Key Lab of Luminescent Materials and Devices (SCUT) (Skllmd-2024-10，Skllmd-2025-05), \u0026nbsp;Science and Technology Program of Guangzhou (2023A04J0988) and Key-Area Research and Development Program of Guangdong Province (2024B0101040001).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eJ. Lou and J. He contributed equally. Conceptualization: J. Lou, J. He and H. Zhang; Methodology: J. Lou, Y. Chen and H. Zhang; Investigation: J. Lou, B. Li and J. He; Writing – Original Draft: J. Lou, and H. Zhang; Writing – Review \u0026amp; Editing: H. Zhang, and Z. Wang; Funding Acquisition: Z. Wang and B. Z. Tang; Resources: Z. Wang and B. Z. Tang; Supervision: Z. Wang and B. Z. Tang.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003cstrong\u003e\u003cbr\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eHu, Y. X. et al. Efficient selenium-integrated TADF OLEDs with reduced roll-off, \u003cem\u003eNat. Photon\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e \u003cstrong\u003e16\u003c/strong\u003e, 803\u0026minus;810 (2022).\u003c/li\u003e\n\u003cli\u003eChen, G. et al. 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Chem.\u003c/em\u003e \u003cstrong\u003e33\u003c/strong\u003e, 580 (2011).\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"organic light-emitting diode, power efficiency, exciton utilization, exciplex, hot-exciton","lastPublishedDoi":"10.21203/rs.3.rs-6904824/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6904824/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003ePower efficiency (PE) is crucial for evaluating organic light-emitting diode (OLED) performance, as it directly reflects photoelectric conversion efficiency. Exciplexes, featuring low injection barriers, offer greater potential than single compounds for high PE, but slow exciton dynamics hinder their development. Here, we introduce a novel strategy of hot-exciton-assisted exciplex (HEAE), which enhances the electroluminescence performance of exciplex systems from aspects of exciton and carrier dynamics. The feature of recovered exciton energy and accelerated reverse intersystem crossing process driven by the hot-exciton material improved the exciton utilization within the exciplex. As a result, the concepted exciplex showsa twice external quantum efficiency (EQE) of 19.0% than exciplex systems composed of conventional materials. Meanwhile, the moderate electron mobilityof hot-exciton material facilitates carrier transportbetween donors, enabling barrier-free injection in concepted exciplex-based OLEDs, which achieve a maximum PE up to82.1 lm W⁻¹. To further prove the superiority of the HEAE system, the exciplex-sensitized fluorescence OLEDs with narrow emission are designed, affording high EQEs of up to 40.5% and setting a new record for breakthrough PE exceeding 230 lm W⁻¹.\u003c/p\u003e","manuscriptTitle":"Ultra-high power efficiency organic light-emitting diodes based on hot-exciton-assisted exciplex (HEAE) system","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-02 17:39:31","doi":"10.21203/rs.3.rs-6904824/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"b3727502-f8be-47b2-92c5-b189515ee507","owner":[],"postedDate":"July 2nd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":50765321,"name":"Physical sciences/Optics and photonics/Lasers, LEDs and light sources/Organic LEDs"},{"id":50765322,"name":"Physical sciences/Physics/Electronics, photonics and device physics/Photonic devices"}],"tags":[],"updatedAt":"2025-08-12T03:15:37+00:00","versionOfRecord":[],"versionCreatedAt":"2025-07-02 17:39:31","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6904824","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6904824","identity":"rs-6904824","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}