Reduced Efficiency Roll-Off of Terdentate Chloroplatinum Emitter-Based Solution-Processed OLEDs Through an Oxygen-Bridged N∧C∧N Polypyridyl Ligand

Reduced Efficiency Roll-Off of Terdentate Chloroplatinum Emitter-Based Solution-Processed OLEDs Through an Oxygen-Bridged N∧C∧N Polypyridyl Ligand | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 12 January 2026 V1 Latest version Share on Reduced Efficiency Roll-Off of Terdentate Chloroplatinum Emitter-Based Solution-Processed OLEDs Through an Oxygen-Bridged N∧C∧N Polypyridyl Ligand Authors : Ren-Hui Zheng , Jian-Cheng Chen , Meng-Jiao Xu , Chen-Yun Kong , Si-Hai Wu 0000-0001-6188-3896 [email protected] , Zhe Zhang , Dian-Xue Ma , Zifeng Zhao , Jiang-Yang Shao , and Yu-Wu Zhong Authors Info & Affiliations https://doi.org/10.22541/au.176819058.84485027/v1 Published Inorganic Chemistry Version of record Peer review timeline 160 views 74 downloads Contents Abstract Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Platinum complexes are highly promising emitters in the development of high-performance organic light-emitting diodes (OLEDs). However, solution-processed OLEDs of platinum complexes suffer from the severe efficiency roll-off at high luminance that greatly impede their commercial applications. To address this issue, three terdentate chloroplatinum emitters Pt1 − Pt3 are designed and synthesized by using oxygen-bridged N ∧ C ∧ N terdentate ligands to suppress efficiency roll-off in device. As indicated by the X-ray single-crystal analysis, these emitters possess similar square-planar configuration but exhibit different intermolecular interactions. Among them, Pt1 achieves excellent solubility (∼21 mg mL −1 ), good film-forming ability, high photoluminescence quantum yield (91%), and short excited-state lifetime (2.58 μs). Solution-processed OLEDs based on Pt1 exhibit a maximum external quantum efficiency (EQE max ) of 15.02% with a small efficiency roll-off (Roll-off 1000 = 6.72%) at the practical luminance brightness level of 1000 cd m −2 . More importantly, the large-area (100 mm 2 ) OLEDs of Pt1 with a decent EQE max of 6.01% and a negligible efficiency roll-off (Roll-off 1000 = 0.99%) at 1000 cd m −2 have been realized, representing one of the highest performance recorded to date based on the terdentate platinum complexes. This work provides an effective molecular design strategy to develop terdentate platinum emitter-based highly efficient solution-processed OLEDs with small efficiency roll-off. Cite this paper: Chin. J. Chem. 2026 , 44 , XXX—XXX. DOI: 10.1002/cjoc.70XXX Reduced Efficiency Roll-Off of Terdentate Chloroplatinum Emitter-Based Solution-Processed OLEDs Through an Oxygen-Bridged N ∧ C ∧ N Polypyridyl Ligand Ren-Hui Zheng, a ,† Jian-Cheng Chen, b ,† Meng-Jiao Xu, a Chen-Yun Kong, a Si-Hai Wu,* , a Zhe Zhang, c Dian-Xue Ma, c Zifeng Zhao, d Jiang-Yang Shao, e , * and Yu-Wu Zhong b , c , * a School of Medicine, Huaqiao University, Quanzhou 362021, China b Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Key Laboratory of Photochemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China c Institute of Molecular Engineering Plus, College of Chemistry, Fuzhou University, Fuzhou 350108, China d AI for Science Institute, Beijing 100084, China e Beijing Key Laboratory for Optical Materials and Photonic Devices, Department of Chemistry, Capital Normal University, Beijing 100048, China Organic light-emitting diodes | Efficiency roll-off | Platinum complex | Terdentate ligand | Large area | Comprehensive Summary Platinum complexes are highly promising emitters in the development of high-performance organic light-emitting diodes (OLEDs). However, solution-processed OLEDs of platinum complexes suffer from the severe efficiency roll-off at high luminance that greatly impede their commercial applications. To address this issue, three terdentate chloroplatinum emitters Pt1 − Pt3 are designed and synthesized by using oxygen-bridged N ∧ C ∧ N terdentate ligands to suppress efficiency roll-off in device. As indicated by the X-ray single-crystal analysis, these emitters possess similar square-planar configuration but exhibit different intermolecular interactions. Among them, Pt1 achieves excellent solubility (∼21 mg mL −1 ), good film-forming ability, high photoluminescence quantum yield (91%), and short excited-state lifetime (2.58 μs). Solution-processed OLEDs based on Pt1 exhibit a maximum external quantum efficiency (EQE max ) of 15.02% with a small efficiency roll-off (Roll-off 1000 = 6.72%) at the practical luminance brightness level of 1000 cd m −2 . More importantly, the large-area (100 mm 2 ) OLEDs of Pt1 with a decent EQE max of 6.01% and a negligible efficiency roll-off (Roll-off 1000 = 0.99%) at 1000 cd m −2 have been realized, representing one of the highest performance recorded to date based on the terdentate platinum complexes. This work provides an effective molecular design strategy to develop terdentate platinum emitter-based highly efficient solution-processed OLEDs with small efficiency roll-off. Background and Originality Content Phosphorescent platinum complexes are one of the most promising emitters for organic light-emitting diodes (OLEDs) applications because of their high photoluminescence quantum yields (PLQYs), good chemical stability, easily tunable excited-state properties, as well as to achieve a nearly-unity internal quantum efficiency (IQE) owing to the strong spin-orbit coupling (SOC) effect. [1−5] Among these platinum complexes with different coordination modes, terdentate chloroplatinum complexes are highly appealing for OLEDs applications due to their attractive features of simple molecular structures, easy purification procedures, and high production yields. [6−7] Till now, terdentate chloroplatinum complexes-based blue, green, red, and near-infrared OLEDs have been successfully fabricated by using either a vacuum evaporation or solution-processed method. [8–12] However, terdentate chloroplatinum complexes show relatively inferior emission properties [13] and unfavorable for its device performance in comparison to those of bidentate and tetradentate analogues. [14–16] Thus, the design of highly luminescent terdentate chloroplatinum complexes is great importance in the development of high-performance OLEDs for practical applications. One strategy to improve device performance of terdentate platinum complex-based OLEDs is to modify the electronic properties of the terdentate ligand through substituent effect. For instance, Yam and co-workers reported a bipolar terdentate platinum complex with carbazole and oxadiazole substituents that shows a high external quantum efficiency (EQE) of 16.0% in solution-processed OLEDs. [17] Due to introduce an ILCT (intraligand charge transfer) character into the excited states, inserting an electron-donating heteroatom or group into the backbone of terdentate ligand is an alternative design strategy to construct highly luminescent terdentate platinum complex for OLEDs applications. [18] In a previous work, a nonplanar terdentate chloroplatinum emitter, Pt(NCH 3 )Cl , with a high EQE of 16.14% in solution-processed OLEDs was realized by inserting an electron-donating N(CH 3 ) group into the backbone of the classical terdentate ligand 1,3-di(2-pyridyl)benzene (dpb) (Figure 1). [19] However, phosphorescent metal complexes-based solution-processed OLEDs usually suffer from severe efficiency roll-off [20−24] owing to the triplet-involved annihilation processes [25] that greatly impede their commercial applications. The long excited-state lifetimes of phosphorescent emitters play a crucial role in triplet-associated annihilation processes and thus result in severe efficiency roll-off at high luminance in OLEDs. To mitigate the roll-off issue, one effective strategy is the design of phosphorescent metal complexes with shorter excited-state lifetimes by tuning the electronic properties of the ligand. [26−28] With this consideration in mind, a new series of terdentate chloroplatinum emitters Pt1 − Pt3 is designed and synthesized by changing from N(CH 3 ) group to oxygen atom in the backbone of the Figure 1 Molecular design strategy of terdentate chloroplatinum emitter. terdentate ligand to decrease excited-state lifetime of the complex (Scheme 1). Compared with the previously reported terdentate chloroplatinum emitter Pt(NCH 3 )Cl , [19] Pt1 exhibits shorter excited-state lifetime in emissive layer ( 6.87 and 10.23 μs for Pt1 and Pt(NCH 3 )Cl, respectively ). As a result, the green-emitting solution-processed OLEDs of Pt1 with a high maximum external quantum efficiency (EQE max ) of 15.02% and a reduced efficiency roll-off at 1000 cd m −2 (Roll-off 1000 = 6.72%) have been achieved, which is distinctly smaller than the previously reported Pt(NCH 3 )Cl -based device (Roll-off 1000 = 18.22%) (Figure 1). More importantly, Pt1 -based large-area OLEDs with an active area of 100 mm 2 have been successfully fabricated to show a decent EQE max of 6.01% with a negligible efficiency roll-off (Roll-off 1000 = 0.99%). Results and Discussion The synthetic routes of terdentate chloroplatinum complexes Pt1 − Pt3 are described in Scheme 1 and the detailed procedures are presented in Supporting Information (SI). The terdentate chloroplatinum complexes Pt1 − Pt3 were synthesized by using a three-step synthetic procedure. First, the starting materials 1 − 3 were obtained by using a nucleophilic substitution reaction of 2-bromopyridine with 3-bromophenol derivatives in synthetic yields of 62−88%. And then, the starting materials reacted with 2-(tributylstannyl)pyridine under a Stille reaction condition to prepare terdentate ligands L1 ‒ L3 with high synthetic yields (79−90%). [29] Finally, the refluxed reaction of terdentate ligand with K 2 PtCl 4 was used to synthesize the terdentate chloroplatinum complexes Pt1 − Pt3 with high synthetic yields (84−91%). [30] The chemical structures of these new compounds were fully characterized by 1 H and 13 C NMR (Figures S1−S18), high-resolution mass spectroscopy, and elemental analysis. The chemical structure of Pt1 − Pt3 were further identified by X-ray single-crystal technique. All the three single crystals of Pt1 − Pt3 were prepared by the slow diffusion of petroleum ether into a dichloromethane solution of the complex. Scheme 1 The Synthetic Routes of Ligands L1 – L3 and Complexes Pt1 – Pt3 . Figure 2 The single-crystal X-ray structures and crystal packings of Pt1 (a, d), Pt2 (b, e), and Pt3 (c, f). The thermal ellipsoids are set at 50% probability. Hydrogens and solvents are deleted for clarity. The ORTEP diagrams of Pt1 − Pt3 are presented in Figure 2 and the corresponding crystallographic data are collected in Tables S1−S2 in the SI. In comparison to the previously reported terdentate chloroplatinum complex Pt(NCH 3 )Cl with nonplanar coordination geometry, [19] all the three complexes display square-planar configuration with similar Pt−N, Pt−C, and Pt−Cl bond lengths in the range of 2.018(11)−2.058(11), 1.941(12)−1.970(2), and 2.403(4)−2.417(12) Å, respectively. In comparison, the C11‒Pt1‒N2 bite angles (90.0−91.1°) of these complexes embedded in six-membered rings are distinctly larger with respect to the C11‒Pt1‒N1 bite angle (80.4−81.2°) embedded in five-membered rings (Figure 2a−2c). Similar results have been reported in our previously works. [30−35] As shown in Figure 2d−2f, different stacking behaviors of these complexes are observed in the crystalline state. For instance, the intermolecular Pt···Pt distances are determined to be 4.446, 5.001, and 4.237 Å for Pt1 − Pt3 , respectively, indicating the absence of Pt···Pt interactions in these complexes. [36−37] In contrast, a smaller aromatic plane to plane distance of Pt3 (3.742 Å) was observed with respect to the Pt1 and Pt2 (4.075 and 5.001 Å), which is shorter than the conventional π − π stacking distance. [38] This suggests that the weak π − π interaction is included in the complex Pt3 . It is consistent with the emission studies of these complexes (see detailed discussion below). The absorption spectra of Pt1 − Pt3 in CH 2 Cl 2 solutions are presented in Figure 3a. These complexes display intense absorption bands in the UV region which are attributed to π ‒ π * excitations of the ligands. In the visible region, the broad absorption bands centered at 414, 441, and 412 nm are observed for Pt1‒Pt3, respectively (Table 1) . As illustrated by theoretical calculations below, these broad absorption bands are assigned to the admixtures of π ‒ π * intraligand (IL) and ILCT (intraligand charge-transfer from the phenol unit to pyridine ring) transitions of terdentate ligands. In comparison, 27 nm red shift and 2 nm blue shift are observed for Pt2 with a −OMe group and Pt3 with a −CF 3 group on the phenyl ring with respect to the parent complex Pt1. Figure 3b displays the excitation spectra of Pt1−Pt3 in CH 2 Cl 2 at room temperature. The comparison of absorption and excitation shows well-matched in the visible region (375−475 nm) (Figure S19), suggestive of an admixture of IL and ILCT character of the emissive excited states in these complexes. Figure 3c−3d shows the emission spectra of Pt1‒Pt3 in CH 2 Cl 2 solutions and 2 wt% doped PMMA (PMMA = polymethylmethacrylate) films at room temperature. Under excitations, Pt1−Pt3 display identical emission colors with emission maximum at 489, 541, and 484 nm both in CH 2 Cl 2 solutions and PMMA films (Table 1). For instance, Pt1 and Pt3 show similar green emission colors with Figure 3 (a) UV/vis absorption spectra of Pt1 – Pt3 in CH 2 Cl 2 (2 × 10 −5 M). (b) Normalized excitation spectra of Pt1 – Pt3 in CH 2 Cl 2 . (c, d) Normalized emission spectra of Pt1 – Pt3 in CH 2 Cl 2 and PMMA films upon excitation at 400 nm. (e, f) Decay profiles of Pt1 – Pt3 in CH 2 Cl 2 and PMMA films at rt. Inset: images of Pt1 – Pt3 in CH 2 Cl 2 and PMMA films under a UV lamp (365 nm). Table 1 Photophysics data of complexes Pt1 – Pt3 . a CH 2 Cl 2 film powder CH 2 Cl 2 film CH 2 Cl 2 e film f Pt1 259 (0.25), 298 (0.15), 334 (0.12), 414 (0.02) 489 489 497 2.58 9.37 77% 91% 2.98 0.89 Pt2 263 (0.19), 307 (0.13), 334 (0.07), 441 (0.02) 541 541 537 0.84 10.7 47% 89% 5.60 6.31 Pt3 261 (0.26), 292 (0.15), 330 (0.10), 412 (0.02) 484 484 622 2.36 8.59 68% 39% 2.88 1.36 a A conventional 1.0 cm quartz cell was used to record the spectra (2 × 10 −5 M). b The absorption spectra were obtained in CH 2 Cl 2 . c The excitation wavelength is 400 nm for Pt1 − Pt2 and 450 nm for Pt3 both in CH 2 Cl 2 and PMMA films, respectively, and 420 nm for all compounds studied in powder. d The emission decay profiles were recorded in CH 2 Cl 2 and PMMA films. e The quantum yields were determined by using [Pt(dpb)Cl] (excited at 400 nm and PLQY = 60%) as a reference in degassed CH 2 Cl 2 . f The absolute quantum yields were determined by using an integrating sphere. g The radiative ( k r ) and nonradiative ( k nr ) rate constants were determined by using the equation of k r = Φ / τ and k nr = (1− Φ )/ τ , respectively. emission maximum at 489 and 484 nm in degassed CH 2 Cl 2 solutions, respectively, while Pt2 with a −OMe group on the phenyl ring exhibits orange emission color with a 52 nm red shift with respect to the complex Pt1. In solid state, Pt1 and Pt2 display similar green and orange emission colors with emission maximum at 497 and 537 nm in comparison to those of CH 2 Cl 2 solutions, while Pt3 with a −CF 3 group on the phenyl ring exhibits red emission color with a significant 138 nm red-shift with respect to the CH 2 Cl 2 solution (Figure S20). This indicated the presence of intermolecular stacking in the pure powder of Pt3 which is consistent with the below concentration-dependent emission studies. In degassed CH 2 Cl 2 solutions, Pt1 shows a PLQY of 77%, which is higher than the model terdentate N ∧ C ∧ N chloroplatinum complex [Pt(dpb)Cl] (60% in CH 2 Cl 2 ), [6] while Pt2−Pt3 exhibit relatively lower PLQYs of 47% and 68%, respectively. This indicates that the introduction of substituents may increase molecular vibrations and enhance the rate constant of the nonradiative process. Furthermore, the radiative rate constants were calculated to be 2.98 × 10 5 , 5.60 × 10 5 , and 2.88 × 10 5 s −1 , as well as the nonradiative rate constants of 0.89 × 10 5 , 6.31 × 10 5 , and 1.36 × 10 5 s −1 for Pt1−Pt3, respectively. [39] In PMMA films, the absolute quantum yields of Pt1−Pt3 were determined to be 91%, 89%, and 39%, respectively. In emission decay studies, Pt1−Pt3 exhibit excited-state lifetimes in the microsecond range both in the CH 2 Cl 2 solutions and PMMA films (2.58, 0.84, and 2.36 μs for CH 2 Cl 2 , 9.37, 10.7, and 8.59 μs for PMMA films, respectively). In degassed CH 2 Cl 2 solutions, these complexes show different aggregation behavior. For instance, the emission shape and maximum of Pt1−Pt2 are independent on the concentration used and no lower-energy excimer emission appears in the range from 3.0 μmol L −1 to 1.3 mmol L −1 , indicating the absence of Pt···Pt and π - π interactions in the such range of concentrations (Figure S21). In comparison, Pt3 shows wide emission colors ranging from green to red (emission maximum ranging from 484 to 621 nm) with the concentrations increasing from 1.0 μmol L −1 to 10 mmol L −1 , which is line with the above observed intermolecular π - π stacking in the crystal state (Figure S22). In order to illustrate the electronic transitions of these complexes, density functional theory (DFT) calculations were carried out on Pt1−Pt3 by using Gaussian 09 package. Pt1−Pt3 exhibit similar highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) contributions from platinum component and terdentate ligand (Figures S23−S25). The distributions of HOMOs are mainly associated with phenol unit and platinum ion, while the terdentate ligand dominates the LUMOs distributions. In comparison to the energy levels (−5.89 and −2.02 eV for HOMO and LUMO, respectively) of the parent complex Pt1, the introduction of strong electron-donating −OMe group can destabilize both the HOMO and LUMO energy levels (−5.58 and −1.99 eV for Pt2), while introduction of strong electron-withdrawing −CF 3 group can stabilize both the HOMO and LUMO energy levels (−6.07 and −2.16 eV for Pt3). The frontier energy gaps are further determined to be 3.87, 3.59, and 3.91 eV for Pt1−Pt3, respectively (Figure S26). As indicated by the time-dependent DFT (TDDFT) calculation results (Figure S27 and Table S3), all the S 1 states ( λ = 397 nm and f = 0.0372, λ = 430 nm and f = 0.0500, and λ = 391 nm and f = 0.0379 for Pt1‒Pt3, respectively) of these complexes are dominated by HOMO → LUMO transition which is responsible for the observed absorption bands at 414, 441, and 412 nm for Pt1‒Pt3, respectively. This suggests that the emissive states of these complexes have an admixture of IL and ILCT character. Similar findings have been reported in our previous works. [19, 30] In order to investigate the electroluminescent properties of these chloroplatinum complexes, Pt1 was selected as the emitter in the fabrication of solution-processed OLEDs because of its excellent solubility (∼21 mg mL −1 both in chlorobenzene and dichloromethane) and emission properties. A series of solution-processed OLEDs of Pt1 were fabricated to optimize the device architecture and the optimization data are presented in SI. First, the host materials, including 3,3’-di(9H-carbazol-9-yl)-1,1’-biphenyl (mCBP), tris(4-carbazoyl-9-ylphenyl)amine (TCTA), 1,3,5-tris(1-phenyl-1H-benzo[d]imidazol-2-yl)benzene (TPBi), 1,1-Bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC), 4,4’-bis(carbazol-9-yl)biphenyl (CBP), and 1,3-bis(5-(4-tert-butylphenyl)-1,3,4-oxadiazol-2-yl)benzene (OXD-7), were studied its effect on device performance (Figure S28 and Table S4). After that, the dopant concentrations (1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, and 7 wt%) of Pt1 and total mass concentrations (15 mg mL −1 , 20 mg mL −1 , and 25 mg mL −1 ) of emissive layer (EML) were investigated (Figures S29−S30 and Tables S5−S6). Finally, the thickness of electron transport layer (ETL) was further optimized to improve the device performance (Figure S31 and Tables S7). The optimized device structure of Pt1 was determined to be ITO/PEDOT:PSS (40 nm)/TCTA:Pt1:OXD-7 (47.5:5:47.5 wt%, 50 nm)/TPBi (50 nm)/LiF (1.5 nm)/Al (100 nm) (Figure 4a). In this architecture, PEDOT:PSS was used as the hole-injecting and hole-transporting layers, while LiF and TPBi were employed as electron-injecting and electron-transporting layers. In order to balance the carrier transport, a mixture of OXD-7 and TCTA with a weight ratio of 1:1 was served as co-host materials. The molecular structures of these above-mentioned functional materials are presented in Figure 4a. The energy level of Pt1 was calculated by using the electrochemical result (Figure S32), while the energy levels of other functional materials were obtained in a previous work (Figure 4a). [19] At the optimized dopant concentration of 5 wt%, the device of Pt1 shows green Figure 4 (a) Solution-processed OLEDs structure of Pt1 and chemical structure of functional materials. (b) Normalized EL spectra. (c) Current density ( J )-voltage ( V )-luminance ( L ) curves. (d) EQE versus luminance. (e) Current and power efficiency versus luminance. (Inset: images of devices based on Pt1 ). emission color with emission maximum at 494 nm and corresponding CIE coordinate of (0.30, 0.57), which is basically matching with emission profile in fluid solution. Moreover, the device of Pt1 displays good color stability in the range from 3.0 V and 12.0 V (Figure S33). As shown in Figure 4b−4e and Table 2, the device of Pt1 exhibits a low turn-on voltage of 3.0 V and a maximum luminance of ( L max ) 6648 cd m −2 , a high EQE max of 15.02%, a maximum current efficiency (CE max ) of 27.79 cd A −1 , and a maximum power efficiency (PE max ) of 17.53 lm W −1 , respectively. Notably, the device of Pt1 also demonstrated that a reduced efficiency roll-off of 6.72% has been achieved at practical brightness level of 1000 cd m −2 in comparison to the previously reported terdentate chloroplatinum emitter Pt(NCH 3 )Cl (Roll-off 1000 = 18.22%), as well as the classical terdentate chloroplatinum emitter [Pt(dpb)Cl] (Roll-off 1000 = 14.92%) (Figures S34−S35). Furthermore, benefiting from its excellent solubility and good film-forming ability, the large-area OLEDs of Pt1 with an emitting area of 12 mm × 8.4 mm were fabricated under the same conditions with conventional devices. The large-area OLEDs of Pt1 display identical EL spectra with respect to the conventional device and uniform green emission color (Figure 4a). The EQE max , CE max , PE max , and L max of large-area OLEDs based on Pt1 were determined to be 6.01%, 12.86 cd A −1 , 3.79 lm W −1 , and 2116 cd m −2 , respectively, corresponding to a negligible efficiency roll-off (Roll-off 1000 = 0.99%) at 1000 cd m −2 , which is representing one of the highest performance recorded to date based on the terdentate platinum complexes. In order to illustrate the low efficiency roll-off of Pt1-based devices, the excited-state lifetimes of the optimized EML films were determined to be 6.87, 9.38 and 10.23 μs for Pt1, [Pt(dpb)Cl], and Pt(NCH 3 )Cl, respectively (Figure S36), indicating that the introduction of oxygen atom to the terdentate ligand can decrease the excited-state lifetimes of EML film to inhibit the triplet-involved annihilation processes effectively and thus improve the efficiency roll-off of the device. [40] Conclusions In summary, three terdnetate chloroplatinum emitters Pt1−Pt3 were designed and synthesized based on oxygen-bridged N^C^N terdentate ligand with various substituents. The substituent effect in photophysical properties and intermolecular interactions of these emitters have been studied. As determined by single-crystal X-ray analysis, no intermolecular interactions were observed in Pt1 and Pt2, while Pt3 with a −CF 3 group on the phenyl ring exhibits intermolecular π - π stacking and thus result in wide-color gamut emission ranging from 484 to 621 nm in degassed CH 2 Cl 2 solution. Specifically, Pt1 shows an excellent solubility of ∼21 mg mL −1 , a short excited-state lifetime of 2.58 μs, and a high PLQY of 91%. As a result, the Pt1-based conventional (4 mm 2 ) and large-area (100 mm 2 ) solution-processed OLEDs achieve EQE max of 15.02% and 6.01%, along with suppressed efficiency roll-off of 6.72% and 0.99% at 1000 cd m −2 , respectively. In comparison, the efficiency roll-off of Pt1 (Roll-off 1000 = 6.72%) is distinctly smaller than the previously reported terdentate chloroplatinum emitters [Pt(dpb)Cl] (Roll-off 1000 = 14.92%) and Pt(NCH 3 )Cl (Roll-off 1000 = 18.22%) in the conventional devices. This study provides a promising strategy to mitigate the roll-off issue of terdentate platinum complex-based solution-processed OLEDs. Table 2 Key parameters of solution-processed OLEDs based on Pt1 . Pt1 4 5 3.0 494 15.02 27.79 17.53 6648 6.72 0.30, 0.57 Pt1 100 5 5.5 494 6.01 12.86 3.79 2116 0.99 0.30, 0.56 a Turn-on voltage (1 cd m −2 ). b The emission maximum in EL spectra. c The maximum external quantum efficiency. d The maximum current efficiency. e The maximum power efficiency. f The maximum luminance. g Efficiency roll-off at 1000 cd m −2 . h CIE coordinates at EQE max . Experimental OLEDs fabrication and characterization. The ITO (180 nm, 15 Ω sq −1 ) substrates were subsequently cleaned by sonication in deionized water, acetone, and isopropanol for 15 min each and then treated with ultraviolet ozone for 20 min. First, a PEDOT: PSS solution was filtered through a 0.45 µm filter. Then, it was spin-coated onto ITO at 4000 rpm for 30 s and subsequently annealed at 150 °C for 20 min in air. The substrates were then transferred into a glove box (O 2 < 0.1 ppm, H 2 O < 0.01 ppm) for subsequent processing. The emissive layer was then overlaid by spin-coating at 3000 rpm for 30 s using a mixed solution of TCTA:Pt1:OXD-7 (47.5%:5%:47.5% in mass ratio, total mass concentration 20 mg/mL) in chlorobenzene and subsequently annealed at 110 °C for 30 min. After that, 50 nm of TPBi, 1 nm of LiF and 100 nm of Al were thermally deposited in an inert chamber at a base pressure less than 5 × 10 −5 Pa. The conventional (2 mm × 2 mm) and large-area (12 mm × 8.4 mm) devices of Pt1 were fabricated in the same work conditions. A computer-controlled luminance meter (Photo Research, PR 750) and a source meter (Keithley 2400) were used to record the electroluminescence characteristics and current density-voltage brightness curves of the device at room temperature under ambient condition. Synthesis and characterization. More detailed synthesis methods and characterization are shown in the Supporting Information. Supporting Information The supporting information for this article is available on the WWW under https://doi.org/10.1002/cjoc.70XXX. Acknowledgement Funding supports from the National Natural Science Foundation of China (22004041, 21925112, 22090021, and 22305251), National Key R&D Program of China (2023YFE0125200), and Undergraduate Training Programs for Innovation and Entrepreneurship of Huaqiao University (202510385026 and S202510385006) are greatly acknowledged. References 1. Hong, G.; Gan, X.; Leonhardt, C.; Zhang, Z.; Seibert, J.; Busch, J. M.; Bräse, S. 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DOI: 10.1002/cjoc.70XXX The conventional (4 mm 2 ) and large-area (100 mm 2 ) solution-processed OLEDs of Pt1 achieve EQE max of 15.02% and 6.01%, along with reduced efficiency roll-off of 6.72% and 0.99% at 1000 cd m −2 , respectively. Supplementary Material File (image4.emf) Download 69.49 KB File (image5.emf) Download 121.51 KB File (image6.emf) Download 31.91 MB File (image7.emf) Download 5.72 MB File (image8.emf) Download 5.09 MB Information & Authors Information Version history V1 Version 1 12 January 2026 Peer review timeline Published Inorganic Chemistry Version of Record 30 Apr 2026 Published Copyright This work is licensed under a Non Exclusive No Reuse License. Keywords efficiency roll-off large area organic light-emitting diodes platinum complex terdentate ligand Authors Affiliations Ren-Hui Zheng Huaqiao University View all articles by this author Jian-Cheng Chen Institute of Chemistry Chinese Academy of Sciences View all articles by this author Meng-Jiao Xu Huaqiao University View all articles by this author Chen-Yun Kong Huaqiao University View all articles by this author Si-Hai Wu 0000-0001-6188-3896 [email protected] Huaqiao University View all articles by this author Zhe Zhang Fuzhou University College of Chemistry View all articles by this author Dian-Xue Ma Fuzhou University College of Chemistry View all articles by this author Zifeng Zhao AI for Science Institute View all articles by this author Jiang-Yang Shao Capital Normal University View all articles by this author Yu-Wu Zhong Fuzhou University View all articles by this author Metrics & Citations Metrics Article Usage 160 views 74 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Ren-Hui Zheng, Jian-Cheng Chen, Meng-Jiao Xu, et al. Reduced Efficiency Roll-Off of Terdentate Chloroplatinum Emitter-Based Solution-Processed OLEDs Through an Oxygen-Bridged N∧C∧N Polypyridyl Ligand. Authorea . 12 January 2026. DOI: https://doi.org/10.22541/au.176819058.84485027/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu . Format Please select one from the list RIS (ProCite, Reference Manager) EndNote BibTex Medlars RefWorks Direct import Tips for downloading citations document.getElementById('citMgrHelpLink').addEventListener('click', function() { popupHelp(this.href); return false; }); $(".js__slcInclude").on("change", function(e){ if ($(this).val() == 'refworks') $('#direct').prop("checked", false); $('#direct').prop("disabled", ($(this).val() == 'refworks')); }); Cited by Ren-Hui Zheng, Jian-Cheng Chen, Meng-Jiao Xu, Chen-Yun Kong, Si-Hai Wu, Zhe Zhang, Dian-Xue Ma, Zifeng Zhao, Jiang-Yang Shao, Yu-Wu Zhong, Reduced Efficiency Roll-Off of Terdentate Chloroplatinum Emitter-Based Solution-Processed OLEDs through an Oxygen-Bridged N ∧ C ∧ N Polypyridyl Ligand , Inorganic Chemistry, 65 , 19, (10495-10504), (2026). https://doi.org/10.1021/acs.inorgchem.6c00228 Crossref Loading... View Options View options PDF View PDF Figures Tables Media Share Share Share article link Copy Link Copied! Copying failed. 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