Performance Enhancement of Quasi-2D Perovskite Light-Emitting Diodes Based on Phase Control by Volatile Antisolvent Treatment

Performance Enhancement of Quasi-2D Perovskite Light-Emitting Diodes Based on Phase Control by Volatile Antisolvent Treatment | 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 Research Article Performance Enhancement of Quasi-2D Perovskite Light-Emitting Diodes Based on Phase Control by Volatile Antisolvent Treatment Seung-Beom Cho, Ju-Hyeong Kim, Chang-Xu Li, IL-KYU PARK This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9167259/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract Quasi-two-dimensional (quasi-2D) perovskites have emerged as promising candidates for high-performance light-emitting diodes (LEDs) due to their unique energy funneling mechanism. However, uncontrollable phase distribution during film crystallization often leads to excessive formation of lower n -phases, which hinder efficient charge transport and radiative recombination. In this study, we demonstrate a facile and effective strategy to modulate the phase distribution and crystallinity of quasi-2D perovskite PEA 2 (FA 0.7 Cs 0.3 ) n−1 Pb n Br 3n+1 thin films using a volatile antisolvent, isopropyl alcohol (IPA). Structural and optical investigations revealed that the IPA treatment effectively suppressed the insulating lower n -phases ( n 3). Optimized IPA treatment of 100 µl yields a high photoluminescence quantum yield and balanced energy funneling, whereas excessive IPA (> 300 µl ) leads to phase oversimplification and morphological defects. Consequently, the green LED fabricated with 100 µl of IPA-treated emissive layer achieved a remarkable peak external quantum efficiency of 19.2% and high luminance, representing a nearly fivefold improvement over the pristine device. This work verifies the critical role of volatile antisolvent engineering in tailoring the energy landscape for high-efficiency perovskite optoelectronics. Quasi-2D Perovskite Antisolvent Post-treatment Light-Emitting Diode External quantum efficiency Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1. Introduction Metal halide perovskites have emerged as attractive materials for next-generation optoelectronic applications, particularly in light-emitting diodes (LEDs), owing to their high color purity, tunable emission spectra, and low-cost solution processability [1–6]. Among various perovskite structures, quasi-two-dimensional (quasi-2D) perovskites, represented by the formula L 2 A n−1 M n X 3n+1 , where L is a bulky organic spacer cation, have garnered significant attention [7–9]. Unlike their three-dimensional (3D) counterparts, quasi-2D perovskites naturally form a quantum-well (QW) structure with varying thicknesses that depend on the n value. This unique configuration facilitates an internal energy-funneling process in which photogenerated excitons are rapidly transferred from lower to higher n -phases, providing shallow and deep potential wells, respectively. This cascade-like energy transfer effectively gathers charge carriers in the most radiative domains, significantly enhancing the recombination efficiency and enabling high-efficiency emission even at low current densities [8–11]. Despite these advantages, achieving the theoretical efficiency limit in quasi-2D perovskite-based LEDs remains challenging due to the stochastic nature of phase distribution during rapid film crystallization [9–12]. Recent research trends in the perovskite-based LEDs have shifted from simple composition engineering to sophisticated spatial and dimensional phase control [11–13]. A major bottleneck identified in recent literature is the formation of excessively small n -members, such as n = 1 or 2 [9–13]. While these phases initiate the energy funneling process, an overabundance of horizontally oriented, insulating lower n -phases acts as a barrier to charge transport. It creates non-radiative recombination centers due to the large proportion of surface atoms, leading to significant efficiency roll-off and poor carrier injection. Consequently, recent studies on quasi-2D perovskites have focused on phase homogenization or dimensionality engineering, using additives such as organic salts, Lewis bases, or specialized solvents to suppress parasitic lower n -phases [11–15]. These promote the growth of more conductive, 3D-like, higher n -domains. However, many conventional phase-control methods involve complex chemical additives that may leave non-volatile residues, thereby degrading the long-term stability and electrical contact of the device [16–18]. Therefore, it is necessary to develop a more feasible and kinetically driven approach to modulate the crystallization process without compromising the intrinsic purity of perovskite structures. Although volatile antisolvent engineering offers a promising approach, the precise correlation between antisolvent volatility and the resulting quasi-2D phase evolution remains to be fully elucidated. In particular, for the mixed-cation green-emitting system of PEA 2 (FA 0.7 Cs 0.3 ) n−1 Pb n Br 3n+1 , the impact of post-treatment kinetics on the competition between lower and higher n -phase nucleation remains a critical area of investigation. In this work, we report a highly effective strategy to achieve near-20% external quantum efficiency (EQE) in green LEDs by precisely controlling the phase distribution through a volatile isopropyl alcohol (IPA) antisolvent treatment. By systematically varying the IPA content, we demonstrate that the volatile nature of the solvent effectively washes away or suppresses the initial formation of insulating lower n -phases ( n 3), improving the energy funneling efficiency and reducing non-radiative recombination centers. This structural refinement leads to a peak EQE of up to 19.2%, a nearly fivefold increase over the pristine device (3.9%). This study provides a comprehensive understanding of how volatile solvent kinetics can be harnessed to tailor the dimensional landscape of quasi-2D perovskites, offering a robust and additive-free route toward high-performance perovskite-based displays and light sources. 2. Experimental 2.1. Preparation of quasi-2D perovskite precursor solutions and thin films The qusi-2D perovskite thin films were prepared by spin-coating and annealing processes, as shown in Fig. 1 . Phenylethylammonium bromide (PEABr) was sourced from Greatcell Solar Materials. A variety of high-purity precursors, including cesium bromide (CsBr, 99.999%), formamidinium bromide (FABr₂, 99.999%), and lead(II) bromide (PbBr₂, 99.999%) were procured from Sigma-Aldrich, as were the anhydrous solvents dimethyl sulfoxide (DMSO, ≥ 99.9%), poly(vinylpyrrolidone) (PVP, Mw = 1 300 000), and chlorobenzene (≥ 99.8%). Indium tin oxide (ITO)-coated glass substrates and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS, AI 4083) were obtained from Ossila. Additionally, 1,3,5-tris(1-phenyl-1H-benzo[d]imidazol-2-yl)benzene (TPBi, ≥ 97%) and 8-quinolinolato lithium (Liq, ≥ 99.9%) were provided by Sigma-Aldrich. Unless otherwise specified, all chemicals were used as received without additional purification. Quasi-2D perovskite precursor solutions were formulated by dissolving PbBr₂, FABr, PEABr, and CsBr with molar ratios of 0.4 : 0.22 : 0.16 : 0.096 in anhydrous DMSO solvent. The chemical framework of the as-prepared perovskite follows the general formula of PEA 2 (FA 0.7 Cs 0.3 ) n-1 Pb n Br 3n+1 , in which PEA acts as the organic spacer, while FA and Cs constitute the mixed A-site cations alongside Br halide. The solutions were stirred at 70°C for 24 hours in an Ar-filled glovebox to achieve a homogeneous phase. For thin film fabrication, 60 µl of the precursor was dispensed onto the glass substrate and spin-coated at 4,500 rpm for 45 seconds. Subsequent thermal annealing was performed at 80°C for 10 minutes to yield uniform thin films. Notably, this process was conducted without an antisolvent. Following the initial annealing process, an IPA-based post-treatment was performed. Specifically, IPA with volumes ranging from 0 to 500 µl was dynamically dispensed onto the perovskite films during rotation at 4,500 rpm for 45 seconds. To ensure the complete evaporation of any remaining solvent molecules following this exposure, the resulting thin films were annealed at 90°C for 10 minutes. 2.2. Fabrication of quasi-2D perovskite-based green LEDs The quasi-2D perovskite LEDs were constructed with a layered configuration of ITO/PEDOT:PSS/PVP/quasi-2D perovskite/TPBi/Liq/Al. Initially, ITO-patterned glass substrates were cleaned by sequential ultrasonication in detergent, deionized water, acetone, and isopropyl alcohol, followed by nitrogen drying and ultraviolet–ozone activation. PEDOT:PSS was spin-coated onto the cleaned substrates at 4,000 rpm for 30 seconds and annealed at 120°C for 15 minutes. Between the hole-transport layer and the emission layer, a hydrophilic polymer, PVP, was inserted to improve interface quality [19]. A PVP layer was formed by spin-coating at 4,000 rpm for 60 seconds. The active quasi-2D perovskite-emitting layer was then coated onto the PVP via the aforementioned process. Finally, the electron transport layer (25 nm TPBi) and the cathode (1.0 nm Liq and 80 nm Al) were deposited via thermal evaporation under high vacuum (base pressure < 10 − 6 Torr). All fabrication procedures beyond substrate cleaning were conducted in an Ar-filled glovebox (O 2 , H 2 O < 10 ppm). 2.3. Characterizations and Instruments The structural characteristics of the quasi-2D perovskite thin films were examined via X-ray diffraction (XRD; Bruker D8 Advance diffractometer) and high-resolution scanning electron microscope (FE-SEM; SU8010, Hitachi). Optical properties, including photoluminescence (PL) and electroluminescence (EL), were evaluated using a Maya 2000 plus spectrophotometer integrated with an integrated sphere. The UV-visible absorption spectra were achieved using an Agilent 8453 system. The absolute PL quantum yield (PLQY) was determined using a Hamamatsu Photonics Quantaurus-QY PLUS. To investigate charge carrier dynamics and lifetimes, time-resolved PL (TRPL) measurements were performed using Hamamatsu Photonics C11367-11. Performances of the devices, such as current density-voltage-luminance ( J-V-L ) characteristics and external quantum efficiency (EQE), were measured using an Ossila LED measurement system. 3. Results and discussion 3.1. Phase Control and Structural Properties To optimize the film quality of quasi-2D perovskite thin films, we introduced a post-processing step using IPA as a volatile antisolvent during the fabrication of PEA 2 (FA 0.7 Cs 0.3 ) n-1 Pb n Br 3n+1 , as shown in Fig. 1 (a). For the quasi-2D perovskites, phenethylammonium (PEA) was used as the spacer cation to form a layered perovskite framework. The optical microscopy (OM) images clearly demonstrate the effect of IPA treatment on the surface macro-morphology. The pristine film exhibits a high density of pinholes and pits on the surface, which typically act as non-radiative recombination centers, thereby degrading the emission efficiency. In contrast, the IPA-treated film exhibits a highly uniform, pinhole-free surface, suggesting that rapid evaporation of the volatile antisolvent facilitates effective phase regulation and surface passivation during the secondary annealing process. The microscopic evolution of the surface was further investigated using SEM with IPA volumes ranging from 0 to 500 µl , as shown in Fig. 1 (b). The pristine thin film (IPA 0 µl ) exhibits a significantly rough, discontinuous surface morphology. However, as the IPA volume increases, the surface coverage improves markedly. Notably, at an optimal IPA content of around 100 ~ 300 µl , the grains become more densely packed, resulting in smooth and high-quality morphology. This improvement is attributed to the role of IPA treatment in regulating the crystallization kinetics of the quasi-2D phases, resulting in a more ordered crystalline structure [13]. The cross-sectional SEM images provide crucial evidence regarding the selective impact of the IPA treatment. Despite the dramatic changes in surface roughness and grain uniformity, the thickness of the perovskite layer remains remarkably consistent, maintained at approximately 20.2 ~ 23.8 nm across all conditions. This observation implies that the IPA treatment specifically acts as a surface-selective phase regulator rather than a solvent that removes or redistributes the bulk material. Consequently, the IPA-based antisolvent post-treatment process successfully enhances surface quality and internal phase distribution without altering the fundamental device geometry or active layer thickness, which is vital for maintaining consistent charge-transport properties in light-emitting applications. To investigate the effect of volatile antisolvent treatment on the structural properties and phase distribution of the quasi-2D perovskite films, XRD analysis was performed. As shown in Fig. 2 , the XRD patterns exhibit a significant structural evolution as the IPA treatment content increases. The pristine film (without IPA treatment) shows a distinct diffraction peak at a low angle of approximately 2θ = 3.2°, corresponding to the (001) plane of the lower n -phases ( n < 2), marked with a diamond symbol [12–16]. This indicates that without additional solvent engineering, the quasi-2D perovskite thin films contain a substantial amount of smaller n -phases. Upon introducing the IPA, the intensity of the lower n -phase peak ( 2θ = 3.2°) gradually diminishes and almost completely disappears at higher IPA volumes above 300 µl . Simultaneously, the diffraction peaks at 15.8° and 31.2°, corresponding to the (100) and (200) planes of the higher n -phases ( n > 3), become significantly sharper and more intense. Specifically, at 500 µl of IPA treatment, the (100) and (200) peaks exhibit the highest intensities and reduced full widths at half maximum (FWHM). This indicates a remarkable improvement in crystallinity and the formation of highly oriented higher n -phase perovskite grains. The transition from lower to higher n -phases through IPA treatment can be attributed to modulated crystallization kinetics and solubility-induced phase redistribution. IPA acts as a volatile antisolvent that can partially dissolve the organic spacers (PEA + ) and intermediate species at the film surface [11–13]. The smaller n -phases, which are typically formed rapidly during the initial spin-coating stage due to their lower formation energy, are redistributed as the IPA promotes the diffusion of FA + and Cs + ions into the lattice. The volatile nature of IPA facilitates the removal of residual solvent and modulates the nucleation rate. This allows for the Ostwald ripening-like process, in which smaller, less stable lower n -phases are consumed to form more thermodynamically stable higher n -phases. The disappearance of the 3.2° peak suggests that the IPA treatment effectively suppresses the formation of insulating, horizontally oriented lower n quantum wells, favoring the growth of three-dimensional (3D) higher n -domains that are beneficial for efficient charge transport during device operation. Therefore, the XRD results demonstrate that the IPA treatment effectively induces a phase transition from lower to higher n -phases in the quasi-2D perovskite framework. By increasing the IPA volume to 500 µl , the characteristic low n -phase diffraction peak at 3.2° is successfully eliminated, yielding a film dominated by higher n -phases with superior crystallinity and preferred orientation, as evidenced by the intensified (100) and (200) reflections. 3.2. Optical Properties of Phase-Controlled Quasi-2D Perovskite Thin Films To further corroborate the phase evolution observed in XRD, UV-visible absorption and photoluminescence (PL) spectra were analyzed, as shown in Fig. 3 . The optical data clearly demonstrate a systematic transition in the dimension of the perovskite phases upon IPA treatment. As shown in Fig. 3 (a), the absorption spectrum of the pristine film exhibits multiple distinct excitonic absorption peaks in the short wavelength region (< 500 nm), which are characteristic of lower n -quasi-2D phases ( n < 2). As the IPA content increases from 100 to 500 µl , the intensity of these excitonic peaks corresponding to the lower n -phases significantly diminishes. This trend indicates a reduction in the population of lower n -phases, consistent with the disappearance of the XRD peaks corresponding to these phases. The PL spectra also show a dominant emission peak with a noticeable redshift and increased intensity upon IPA treatment, as shown in Fig. 3 (b). The pristine thin film exhibits a relatively weak emission peak centered at 508 nm. Upon increasing the IPA treatment volume to 500 µl , the PL peak shifts to 515 nm, which is associated with the emission from higher n -phases and 3D-like domains. The PL intensity increases remarkably, suggesting that the IPA treatment reduces non-radiative recombination centers by improving the crystallinity and optimizing the energy landscape. The narrow PL peak at 515 nm, despite the presence of multiple phases in the absorption spectra, confirms efficient energy funneling. The photogenerated excitons are effectively transferred from lower to higher n -phases with smaller bandgap energy before radiative recombination. The observed optical changes are driven by the solvent-engineered phase homogenization. The volatile antisolvent treatment disrupts the rapid and disordered precipitation of PEA-rich lower n -phases during the spin-coating process. By modulating the solubility of the precursor components, IPA facilitates the growth of larger n -domains. In quasi-2D perovskites, a graded energy landscape can be formed. The reduction of excessive lower n -phases and the enhanced formation of higher n -phases create a more efficient path for charge carriers, because these two act as energy barriers and energy sinks, respectively [11–13]. In addition, the IPA treatment facilitates the removal of surface defects and unreacted species, leading to increased PL intensity and a clearer, more saturated green emission observed in the inset images. Therefore, the optical characterization by absorption and PL spectroscopy confirms successful phase modulation in PEA 2 (FA 0.7 Cs 0.3 ) n-1 Pb n Br 3n+1 films based on the IPA antisolvent treatment. The IPA treatment effectively suppresses the formation of lower-n phases, as evidenced by the diminished excitonic absorption peaks, while simultaneously enhancing PL emission in higher n -domains. These results, combined with the structural transition observed in XRD, demonstrate that volatile antisolvent engineering is a critical strategy for achieving high-purity, high-crystallinity quasi-2D perovskite films with optimized energy funneling for efficient optoelectronic applications. To further elucidate the effect of IPA treatment on the radiative recombination and charge carrier dynamics, time-resolved PL (TRPL) and PL quantum yield (PLQY) measurements were conducted. As shown in Fig. 4 (a), the PL decay curves for all samples exhibit similar exponential decay profiles. The average PL lifetime ( τ avg ) shows minor variations. The average PL lifetime increases from 2.8 ns (Pristine) to 4.43 ns (100 µl ), then decreases to its minimum of 2.07 ns (300 µl ), before slightly recovering to 4.51 ns (500 µl ). The relatively short lifetime at 300 µl suggests a faster recombination process. Combined with the lower PLQY results, this may indicate an increase in non-radiative recombination pathways or an accelerated energy transfer process that is not efficiently coupled to radiative emission. Figure 4 (b) and (c) show that the PL intensity and PLQY are highly sensitive to the IPA volume. The 100 µl of IPA-treated film shows the highest PLQY, outperforming the pristine one. This enhancement is attributed to an optimized balance of quasi-2D phases, in which an appropriate amount of lower n -phases remains to facilitate efficient energy funneling to the higher n -emissive states. However, a significant reduction in PLQY is observed as the IPA volume exceeds 300 µl . Specifically, the 500 µl sample shows the lowest PLQY, despite exhibiting high crystallinity in XRD. The non-monotonic behavior of PLQY regarding IPA volume can be explained by the trade-off between phase purity and film quality. At 100 µl , the IPA treatment moderately reduces the insulating lower n -phases while maintaining sufficient energy cascade from lower to higher n -phases. This moderate phase distribution minimizes energy loss during charge transfer prior to recombination, thereby improving radiative recombination at the emissive centers. As confirmed by XRD and UV-visible absorption data, the antisolvent treatment with IPA volumes above 300 µl leads to the near-complete disappearance of the lower n -phases. The absence of these donor phases disrupts the energy-funneling mechanism, thereby decreasing PLQY. The drastic reduction in PLQY at high IPA contents may also stem from solvent-induced morphological defects. Excessive volatile antisolvent can cause rapid and aggressive crystallization, potentially leading to increased surface roughness or to the formation of pinholes and grain-boundary defects that act as non-radiative recombination centers. Therefore, the TRPL and PLQY analyses reveal that although IPA treatment is effective for phase modulation, its volume must be precisely controlled to optimize emission efficiency. In this study, a 100 µl IPA treatment provides the ideal phase distribution for maximum PLQY through efficient energy funneling. Conversely, excessive IPA treatment (> 300 µl ) results in a significant reduction in emission efficiency due to excessive suppression of lower n -phases and a possible increase in non-radiative recombination centers caused by deteriorating film quality. 3.3. Performances of LEDs based on Phase-Controlled Quasi-2D Perovskites To evaluate the practical application of the phase-engineered quasi-2D perovskite films, green LEDs were fabricated with the architecture shown in Fig. 5 (a). The device consists of a multi-layered structure: ITO/PEDOT:PSS/PVP/quasi-2D perovskite/TPBi/LiF/Al. The energy band diagram, constructed from literature values, illustrates a well-aligned cascade that enables efficient charge injection into the perovskite emissive layer (EML). The external quantum efficiency (EQE) results for the LEDs treated by various amounts of IPA are presented as a function of current density, as shown in Figs. 5 (b)-(e). The pristine device exhibits a relatively low peak EQE of 3.9%, attributed to excessive insulating spacer ligands and lower n -phases, which act as non-radiative recombination centers, as proven by previous XRD and PLQY analyses. Upon treatment with 100 µl of IPA, the LED shows a remarkable peak EQE of 19.2%, a nearly fivefold improvement over the pristine device. This indicates that the optimized phase redistribution and enhanced crystallinity significantly improve the radiative recombination efficiency of the LED device. The EQE curves for 8 individual pixels per sample show high consistency and minimal deviation, demonstrating the excellent reproducibility and uniformity of the volatile antisolvent-assisted crystallization process. The superior performance of the 100 µl IPA-treated device can be explained by the combined effects of balanced charge injection and funneling, reduced leakage current, and efficiency roll-off at high IPA concentrations. Most of all, the 100 µl IPA treatment optimizes the populations of the lower and higher n -phases, which act as donor- and acceptor-like energy states in the EML, respectively. This promotes an efficient energy-funneling process, in which injected electrons and holes are concentrated in the most radiative higher n -domains, thereby maximizing the LED outputs. In addition, the improved film morphology and crystallinity, as confirmed by XRD measurements, reduce grain boundary defects. This effectively suppresses leakage current and non-radiative Shunt paths, leading to a steep increase in EQE at low current densities. Finally, for the LEDs treated with 300 and 500 µl of IPA, the peak EQE values drop significantly. This trend is consistent with the PLQY results, in which the over-suppression of lower n -phases and the degradation of quasi-2D perovskite thin films hinder effective exciton formation and radiative decay. In this way, integrating IPA-treated quasi-2D perovskite films into green LEDs led to a substantial enhancement in device performance. The electrical properties and operational stability of the quasi-2D perovskite LEDs were systematically investigated to elucidate the impact of IPA-induced phase modulation on device performance. As shown in the current density-voltage-luminance ( J-V-L ) characteristics (Fig. 5 f), the IPA-treated devices exhibit a significantly lower leakage current in the sub-threshold low-voltage region compared to the pristine one. This suppression of leakage current suggests that the improved crystallinity and smooth morphology of the IPA-engineered films effectively passivate non-radiative shunt paths, which are typically prevalent in disordered quasi-2D systems. The luminance profiles exhibit a substantial enhancement upon IPA treatment. Notably, the 100 µl IPA-treated device demonstrates the highest peak luminance and a reduced turn-on voltage. This improvement indicates enhanced charge injection and more efficient radiative recombination, enabled by the optimized quasi-2D energy cascade that directs excitons toward the most radiatively emissive centers. Interestingly, as the IPA volume increases to 500 µl , a slight decrease in current density is observed at equivalent voltages. This trend correlates with the removal of the highly conductive lower n -phases and an increase in grain size, as previously confirmed by XRD, which collectively alter the charge transport kinetics within the EML. The operational stability of the optimized device (100 µl IPA) was evaluated under a constant current density of 0.7 mA/cm² with an initial luminance ( L 0 ) of 1,026 cd/m². The device yielded a half-lifetime ( T 50 ) of 4 minutes, as shown in Fig. 5 (g). While quasi-2D perovskites inherently face stability challenges under high-brightness operation, the observed decay profile likely reflects intrinsic ion migration and Joule heating during continuous bias [20]. The superior performance of the 100 µl IPA-treated device is attributed to optimized charge-injection balance, suppression of non-radiative recombination, and enhanced morphological integrity. By refining the phase distribution, the 100 µl IPA treatment minimizes energetic disorder, thereby promoting balanced electron and hole injection. Furthermore, the dramatic increase in EQE from 3.9 to 19.2% is a direct consequence of reducing the population of defective lower n -phases. This structural refinement suppresses trap-mediated non-radiative recombination, allowing a larger fraction of excitons to decay radiatively at the higher n emission centers. The J-V characteristics further confirm that volatile antisolvent engineering promotes the formation of a denser and pinhole-free film, which is critical for sustaining high luminance at high bias without electrical breakdown. Therefore, these results demonstrate that precise control of the phase distribution via volatile antisolvent treatment not only maximizes the quantum efficiency but also optimizes the electrical driving conditions. This study provides a robust strategy for optimizing energy landscapes in multi-dimensional perovskite systems by offering a comprehensive pathway toward high-performance optoelectronic applications. 4. Conclusions In summary, we have successfully developed high-efficiency green LEDs by employing a volatile antisolvent treatment to engineer the phase redistribution of quasi-2D perovskites. The structural and optical investigations confirmed that the IPA treatment played a critical role in determining the emission properties of the PEA 2 (FA 0.7 Cs 0.3 ) n−1 Pb n Br 3n+1 quasi-2D perovskite thin films. The introduction of 100 µl of IPA effectively eliminated the parasitic lower n -phases, thereby facilitating an optimized energy cascade from lower n - to larger n -phases. This structural refinement resulted in a record-level EQE of 19.2% with high reproducibility across multiple pixels. Although the device stability showed a T 50 of 4 minutes at a high initial luminance of 1,026 cd/m 2 , the significant enhancements in radiative and charge injection efficiencies represented a substantial step forward. These findings provide valuable insights into the crystallization kinetics of multi-dimensional perovskites and offer a promising pathway for developing high-performance emissive layers for advanced display and lighting applications. Declarations CRediT authorship contribution statement S.-B. Cho : Writing-original draft, Conceptualization, Writing-review, Methodology. J.-H. Kim : Data curation, Resources, Investigation, Formal analysis, Writing-review, Methodology, C.-X. Li : Data curation, Investigation, Formal analysis, Methodology, I.-K. Park : Supervision, Resources, Project administration, editing, Funding acquisition. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgments This study was supported by the Research program funded by the Seoultech (Seoul National University of Science & Technology). References K. 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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-9167259","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":612953384,"identity":"f262943e-fdae-4d75-8171-7037492222f1","order_by":0,"name":"Seung-Beom Cho","email":"","orcid":"","institution":"Seoul National University of Science \u0026 Technology","correspondingAuthor":false,"prefix":"","firstName":"Seung-Beom","middleName":"","lastName":"Cho","suffix":""},{"id":612953385,"identity":"148632ae-77dd-433c-9efd-f1a02dcd11d3","order_by":1,"name":"Ju-Hyeong Kim","email":"","orcid":"","institution":"Seoul National University of Science \u0026 Technology","correspondingAuthor":false,"prefix":"","firstName":"Ju-Hyeong","middleName":"","lastName":"Kim","suffix":""},{"id":612953386,"identity":"9cc72e97-8689-434c-82d8-d05a12858452","order_by":2,"name":"Chang-Xu Li","email":"","orcid":"","institution":"Seoul National University of Science \u0026 Technology","correspondingAuthor":false,"prefix":"","firstName":"Chang-Xu","middleName":"","lastName":"Li","suffix":""},{"id":612953387,"identity":"f5727ff9-d108-457f-bf86-797d2cfa9c5c","order_by":3,"name":"IL-KYU PARK","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0klEQVRIie3PPQrCMBTA8VcCz+XVrkKRXqFFUITiWVoKmXWrKFgQ4ujqdaQQFz2BSz2CCKKLmHStpLo55L/kg/xIAmCz/WMMnUqPXT2vd6idsFCPiF8Tdbb3Gxl1kM8feZyKYL2/TWESAJ0qIxmvUZ7pyFOBmPk7yKLC3YRGEpYdcXZEqQgNGQFLwEPzwzSZPV+aeHdFVt8QlOAW9S2oSJmAK8xE/SXzSfKBQD7wKTxEgqSZjDwZXR/LuL9l5eVG+SLwiLc8rLFs+UmD2Gw2m+1Db2BMNFCjFVPfAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0002-0628-8530","institution":"Seoul National University of Science \u0026 Technology","correspondingAuthor":true,"prefix":"","firstName":"IL-KYU","middleName":"","lastName":"PARK","suffix":""}],"badges":[],"createdAt":"2026-03-19 08:55:52","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9167259/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9167259/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105754209,"identity":"ad968a22-cd07-4f91-b38e-ea7e946cef18","added_by":"auto","created_at":"2026-03-30 16:15:34","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":900913,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Schematic fabrication process of the quasi-2D perovskite thin films based on the spin-coating and post-IPA treatment process. The optical microscope images show the quasi-2D perovskite thin films with and without IPA treatment. (b) Surface and cross-sectional SEM images of the quasi-2D perovskite thin films with the variations of IPA contents.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-9167259/v1/f5f7fdf067105ffefceaac5d.jpeg"},{"id":105753793,"identity":"4f01acab-9825-49b9-9f62-c17d931b7d8e","added_by":"auto","created_at":"2026-03-30 16:12:24","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":91693,"visible":true,"origin":"","legend":"\u003cp\u003eNormalized XRD patterns of the quasi-2D perovskite thin films with the variation of IPA treatment content.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-9167259/v1/ce51ea06f74f77f809f1cf24.png"},{"id":105753795,"identity":"d22939ba-bd87-4a27-8420-ea7eece6e3db","added_by":"auto","created_at":"2026-03-30 16:12:24","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":252937,"visible":true,"origin":"","legend":"\u003cp\u003e(a)Normalized UV-visible absorption spectra of the quasi-2D perovskite thin films with the variation of IPA treatment content. (b) PL spectra and emission images of the quasi-2D perovskite thin films with the variation of IPA treatment content.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-9167259/v1/b3c2bf8a682616910414f018.png"},{"id":105754702,"identity":"54e89c31-5550-4552-ad53-9882a881aab6","added_by":"auto","created_at":"2026-03-30 16:20:16","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":218451,"visible":true,"origin":"","legend":"\u003cp\u003e(a) TRPL decay profiles of the quasi-2D perovskite thin films with the variation of IPA treatment content. (b) PL spectra of the quasi-2D perovskite thin films with the variation of IPA treatment content. (c) Normalized PLQY variations of the quasi-2D perovskite thin films with the variation of IPA treatment content.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-9167259/v1/ff753a7b2a2cb976992e0c61.png"},{"id":105754639,"identity":"a55511c8-54f2-4af8-8da4-3a50e7ef6aa4","added_by":"auto","created_at":"2026-03-30 16:19:27","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":392063,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Device architecture and Energy level diagram of the device stack. (b)-(e) EQE versus current density curves for devices with varying IPA content. (f) Current density–voltage–luminance (\u003cem\u003eJ–V–L\u003c/em\u003e) characteristics of the LEDs. (g) Operational lifetime (\u003cem\u003eT\u003c/em\u003e₅₀) curves measured at a constant current density of 0.7 mA/cm². for the LED with IPA content of 100 \u003cem\u003eμl\u003c/em\u003e.\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-9167259/v1/bc29e44a37ed4c71a964955a.png"},{"id":106994070,"identity":"6ea62cdf-1e0a-4a5b-8ae6-48b833557372","added_by":"auto","created_at":"2026-04-15 15:03:38","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2202325,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9167259/v1/2680e9c2-5327-44eb-9b96-a926936a471d.pdf"}],"financialInterests":"","formattedTitle":"Performance Enhancement of Quasi-2D Perovskite Light-Emitting Diodes Based on Phase Control by Volatile Antisolvent Treatment","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eMetal halide perovskites have emerged as attractive materials for next-generation optoelectronic applications, particularly in light-emitting diodes (LEDs), owing to their high color purity, tunable emission spectra, and low-cost solution processability [1\u0026ndash;6]. Among various perovskite structures, quasi-two-dimensional (quasi-2D) perovskites, represented by the formula L\u003csub\u003e2\u003c/sub\u003eA\u003csub\u003en\u0026minus;1\u003c/sub\u003eM\u003csub\u003en\u003c/sub\u003eX\u003csub\u003e3n+1\u003c/sub\u003e, where L is a bulky organic spacer cation, have garnered significant attention [7\u0026ndash;9]. Unlike their three-dimensional (3D) counterparts, quasi-2D perovskites naturally form a quantum-well (QW) structure with varying thicknesses that depend on the \u003cem\u003en\u003c/em\u003e value. This unique configuration facilitates an internal energy-funneling process in which photogenerated excitons are rapidly transferred from lower to higher \u003cem\u003en\u003c/em\u003e-phases, providing shallow and deep potential wells, respectively. This cascade-like energy transfer effectively gathers charge carriers in the most radiative domains, significantly enhancing the recombination efficiency and enabling high-efficiency emission even at low current densities [8\u0026ndash;11]. Despite these advantages, achieving the theoretical efficiency limit in quasi-2D perovskite-based LEDs remains challenging due to the stochastic nature of phase distribution during rapid film crystallization [9\u0026ndash;12]. Recent research trends in the perovskite-based LEDs have shifted from simple composition engineering to sophisticated spatial and dimensional phase control [11\u0026ndash;13]. A major bottleneck identified in recent literature is the formation of excessively small \u003cem\u003en\u003c/em\u003e-members, such as \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1 or 2 [9\u0026ndash;13]. While these phases initiate the energy funneling process, an overabundance of horizontally oriented, insulating lower \u003cem\u003en\u003c/em\u003e-phases acts as a barrier to charge transport. It creates non-radiative recombination centers due to the large proportion of surface atoms, leading to significant efficiency roll-off and poor carrier injection. Consequently, recent studies on quasi-2D perovskites have focused on phase homogenization or dimensionality engineering, using additives such as organic salts, Lewis bases, or specialized solvents to suppress parasitic lower \u003cem\u003en\u003c/em\u003e-phases [11\u0026ndash;15]. These promote the growth of more conductive, 3D-like, higher \u003cem\u003en\u003c/em\u003e-domains. However, many conventional phase-control methods involve complex chemical additives that may leave non-volatile residues, thereby degrading the long-term stability and electrical contact of the device [16\u0026ndash;18]. Therefore, it is necessary to develop a more feasible and kinetically driven approach to modulate the crystallization process without compromising the intrinsic purity of perovskite structures. Although volatile antisolvent engineering offers a promising approach, the precise correlation between antisolvent volatility and the resulting quasi-2D phase evolution remains to be fully elucidated. In particular, for the mixed-cation green-emitting system of PEA\u003csub\u003e2\u003c/sub\u003e(FA\u003csub\u003e0.7\u003c/sub\u003eCs\u003csub\u003e0.3\u003c/sub\u003e)\u003csub\u003en\u0026minus;1\u003c/sub\u003ePb\u003csub\u003en\u003c/sub\u003eBr\u003csub\u003e3n+1\u003c/sub\u003e, the impact of post-treatment kinetics on the competition between lower and higher \u003cem\u003en\u003c/em\u003e-phase nucleation remains a critical area of investigation. In this work, we report a highly effective strategy to achieve near-20% external quantum efficiency (EQE) in green LEDs by precisely controlling the phase distribution through a volatile isopropyl alcohol (IPA) antisolvent treatment. By systematically varying the IPA content, we demonstrate that the volatile nature of the solvent effectively washes away or suppresses the initial formation of insulating lower \u003cem\u003en\u003c/em\u003e-phases (\u003cem\u003en\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;2). Structural and optical investigations showed that an optimized treatment of 100 \u003cem\u003e\u0026micro;l\u003c/em\u003e of IPA induces a favorable phase transition toward higher \u003cem\u003en\u003c/em\u003e-phases (\u003cem\u003en\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;3), improving the energy funneling efficiency and reducing non-radiative recombination centers. This structural refinement leads to a peak EQE of up to 19.2%, a nearly fivefold increase over the pristine device (3.9%). This study provides a comprehensive understanding of how volatile solvent kinetics can be harnessed to tailor the dimensional landscape of quasi-2D perovskites, offering a robust and additive-free route toward high-performance perovskite-based displays and light sources.\u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Preparation of quasi-2D perovskite precursor solutions and thin films\u003c/h2\u003e \u003cp\u003eThe qusi-2D perovskite thin films were prepared by spin-coating and annealing processes, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Phenylethylammonium bromide (PEABr) was sourced from Greatcell Solar Materials. A variety of high-purity precursors, including cesium bromide (CsBr, 99.999%), formamidinium bromide (FABr₂, 99.999%), and lead(II) bromide (PbBr₂, 99.999%) were procured from Sigma-Aldrich, as were the anhydrous solvents dimethyl sulfoxide (DMSO, \u0026ge;\u0026thinsp;99.9%), poly(vinylpyrrolidone) (PVP, Mw\u0026thinsp;=\u0026thinsp;1 300 000), and chlorobenzene (\u0026ge;\u0026thinsp;99.8%). Indium tin oxide (ITO)-coated glass substrates and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS, AI 4083) were obtained from Ossila. Additionally, 1,3,5-tris(1-phenyl-1H-benzo[d]imidazol-2-yl)benzene (TPBi, \u0026ge;\u0026thinsp;97%) and 8-quinolinolato lithium (Liq, \u0026ge;\u0026thinsp;99.9%) were provided by Sigma-Aldrich. Unless otherwise specified, all chemicals were used as received without additional purification.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eQuasi-2D perovskite precursor solutions were formulated by dissolving PbBr₂, FABr, PEABr, and CsBr with molar ratios of 0.4 : 0.22 : 0.16 : 0.096 in anhydrous DMSO solvent. The chemical framework of the as-prepared perovskite follows the general formula of PEA\u003csub\u003e2\u003c/sub\u003e(FA\u003csub\u003e0.7\u003c/sub\u003eCs\u003csub\u003e0.3\u003c/sub\u003e)\u003csub\u003en-1\u003c/sub\u003ePb\u003csub\u003en\u003c/sub\u003eBr\u003csub\u003e3n+1\u003c/sub\u003e, in which PEA acts as the organic spacer, while FA and Cs constitute the mixed A-site cations alongside Br halide. The solutions were stirred at 70\u0026deg;C for 24 hours in an Ar-filled glovebox to achieve a homogeneous phase. For thin film fabrication, 60 \u003cem\u003e\u0026micro;l\u003c/em\u003e of the precursor was dispensed onto the glass substrate and spin-coated at 4,500 rpm for 45 seconds. Subsequent thermal annealing was performed at 80\u0026deg;C for 10 minutes to yield uniform thin films. Notably, this process was conducted without an antisolvent. Following the initial annealing process, an IPA-based post-treatment was performed. Specifically, IPA with volumes ranging from 0 to 500 \u003cem\u003e\u0026micro;l\u003c/em\u003e was dynamically dispensed onto the perovskite films during rotation at 4,500 rpm for 45 seconds. To ensure the complete evaporation of any remaining solvent molecules following this exposure, the resulting thin films were annealed at 90\u0026deg;C for 10 minutes.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Fabrication of quasi-2D perovskite-based green LEDs\u003c/h2\u003e \u003cp\u003eThe quasi-2D perovskite LEDs were constructed with a layered configuration of ITO/PEDOT:PSS/PVP/quasi-2D perovskite/TPBi/Liq/Al. Initially, ITO-patterned glass substrates were cleaned by sequential ultrasonication in detergent, deionized water, acetone, and isopropyl alcohol, followed by nitrogen drying and ultraviolet\u0026ndash;ozone activation. PEDOT:PSS was spin-coated onto the cleaned substrates at 4,000 rpm for 30 seconds and annealed at 120\u0026deg;C for 15 minutes. Between the hole-transport layer and the emission layer, a hydrophilic polymer, PVP, was inserted to improve interface quality [19]. A PVP layer was formed by spin-coating at 4,000 rpm for 60 seconds. The active quasi-2D perovskite-emitting layer was then coated onto the PVP via the aforementioned process. Finally, the electron transport layer (25 nm TPBi) and the cathode (1.0 nm Liq and 80 nm Al) were deposited via thermal evaporation under high vacuum (base pressure\u0026thinsp;\u0026lt;\u0026thinsp;10\u003csup\u003e\u0026minus;\u0026thinsp;6\u003c/sup\u003e Torr). All fabrication procedures beyond substrate cleaning were conducted in an Ar-filled glovebox (O\u003csub\u003e2\u003c/sub\u003e, H\u003csub\u003e2\u003c/sub\u003eO\u0026thinsp;\u0026lt;\u0026thinsp;10 ppm).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Characterizations and Instruments\u003c/h2\u003e \u003cp\u003eThe structural characteristics of the quasi-2D perovskite thin films were examined via X-ray diffraction (XRD; Bruker D8 Advance diffractometer) and high-resolution scanning electron microscope (FE-SEM; SU8010, Hitachi). Optical properties, including photoluminescence (PL) and electroluminescence (EL), were evaluated using a Maya 2000 plus spectrophotometer integrated with an integrated sphere. The UV-visible absorption spectra were achieved using an Agilent 8453 system. The absolute PL quantum yield (PLQY) was determined using a Hamamatsu Photonics Quantaurus-QY PLUS. To investigate charge carrier dynamics and lifetimes, time-resolved PL (TRPL) measurements were performed using Hamamatsu Photonics C11367-11. Performances of the devices, such as current density-voltage-luminance (\u003cem\u003eJ-V-L\u003c/em\u003e) characteristics and external quantum efficiency (EQE), were measured using an Ossila LED measurement system.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Phase Control and Structural Properties\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eTo optimize the film quality of quasi-2D perovskite thin films, we introduced a post-processing step using IPA as a volatile antisolvent during the fabrication of PEA\u003csub\u003e2\u003c/sub\u003e(FA\u003csub\u003e0.7\u003c/sub\u003eCs\u003csub\u003e0.3\u003c/sub\u003e)\u003csub\u003en-1\u003c/sub\u003ePb\u003csub\u003en\u003c/sub\u003eBr\u003csub\u003e3n+1\u003c/sub\u003e, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e(a). For the quasi-2D perovskites, phenethylammonium (PEA) was used as the spacer cation to form a layered perovskite framework. The optical microscopy (OM) images clearly demonstrate the effect of IPA treatment on the surface macro-morphology. The pristine film exhibits a high density of pinholes and pits on the surface, which typically act as non-radiative recombination centers, thereby degrading the emission efficiency. In contrast, the IPA-treated film exhibits a highly uniform, pinhole-free surface, suggesting that rapid evaporation of the volatile antisolvent facilitates effective phase regulation and surface passivation during the secondary annealing process.\u003c/p\u003e \u003cp\u003eThe microscopic evolution of the surface was further investigated using SEM with IPA volumes ranging from 0 to 500 \u003cem\u003e\u0026micro;l\u003c/em\u003e, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e(b). The pristine thin film (IPA 0 \u003cem\u003e\u0026micro;l\u003c/em\u003e) exhibits a significantly rough, discontinuous surface morphology. However, as the IPA volume increases, the surface coverage improves markedly. Notably, at an optimal IPA content of around 100\u0026thinsp;~\u0026thinsp;300 \u003cem\u003e\u0026micro;l\u003c/em\u003e, the grains become more densely packed, resulting in smooth and high-quality morphology. This improvement is attributed to the role of IPA treatment in regulating the crystallization kinetics of the quasi-2D phases, resulting in a more ordered crystalline structure [13]. The cross-sectional SEM images provide crucial evidence regarding the selective impact of the IPA treatment. Despite the dramatic changes in surface roughness and grain uniformity, the thickness of the perovskite layer remains remarkably consistent, maintained at approximately 20.2\u0026thinsp;~\u0026thinsp;23.8 nm across all conditions. This observation implies that the IPA treatment specifically acts as a surface-selective phase regulator rather than a solvent that removes or redistributes the bulk material. Consequently, the IPA-based antisolvent post-treatment process successfully enhances surface quality and internal phase distribution without altering the fundamental device geometry or active layer thickness, which is vital for maintaining consistent charge-transport properties in light-emitting applications.\u003c/p\u003e \u003cp\u003eTo investigate the effect of volatile antisolvent treatment on the structural properties and phase distribution of the quasi-2D perovskite films, XRD analysis was performed. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, the XRD patterns exhibit a significant structural evolution as the IPA treatment content increases. The pristine film (without IPA treatment) shows a distinct diffraction peak at a low angle of approximately \u003cem\u003e2θ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.2\u0026deg;, corresponding to the (001) plane of the lower \u003cem\u003en\u003c/em\u003e-phases (\u003cem\u003en\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;2), marked with a diamond symbol [12\u0026ndash;16]. This indicates that without additional solvent engineering, the quasi-2D perovskite thin films contain a substantial amount of smaller \u003cem\u003en\u003c/em\u003e-phases. Upon introducing the IPA, the intensity of the lower \u003cem\u003en\u003c/em\u003e-phase peak (\u003cem\u003e2θ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.2\u0026deg;) gradually diminishes and almost completely disappears at higher IPA volumes above 300 \u003cem\u003e\u0026micro;l\u003c/em\u003e. Simultaneously, the diffraction peaks at 15.8\u0026deg; and 31.2\u0026deg;, corresponding to the (100) and (200) planes of the higher \u003cem\u003en\u003c/em\u003e-phases (\u003cem\u003en\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;3), become significantly sharper and more intense. Specifically, at 500 \u003cem\u003e\u0026micro;l\u003c/em\u003e of IPA treatment, the (100) and (200) peaks exhibit the highest intensities and reduced full widths at half maximum (FWHM). This indicates a remarkable improvement in crystallinity and the formation of highly oriented higher \u003cem\u003en\u003c/em\u003e-phase perovskite grains. The transition from lower to higher \u003cem\u003en\u003c/em\u003e-phases through IPA treatment can be attributed to modulated crystallization kinetics and solubility-induced phase redistribution. IPA acts as a volatile antisolvent that can partially dissolve the organic spacers (PEA\u003csup\u003e+\u003c/sup\u003e) and intermediate species at the film surface [11\u0026ndash;13]. The smaller \u003cem\u003en\u003c/em\u003e-phases, which are typically formed rapidly during the initial spin-coating stage due to their lower formation energy, are redistributed as the IPA promotes the diffusion of FA\u003csup\u003e+\u003c/sup\u003e and Cs\u003csup\u003e+\u003c/sup\u003e ions into the lattice. The volatile nature of IPA facilitates the removal of residual solvent and modulates the nucleation rate. This allows for the Ostwald ripening-like process, in which smaller, less stable lower \u003cem\u003en\u003c/em\u003e-phases are consumed to form more thermodynamically stable higher \u003cem\u003en\u003c/em\u003e-phases. The disappearance of the 3.2\u0026deg; peak suggests that the IPA treatment effectively suppresses the formation of insulating, horizontally oriented lower \u003cem\u003en\u003c/em\u003e quantum wells, favoring the growth of three-dimensional (3D) higher \u003cem\u003en\u003c/em\u003e-domains that are beneficial for efficient charge transport during device operation. Therefore, the XRD results demonstrate that the IPA treatment effectively induces a phase transition from lower to higher \u003cem\u003en\u003c/em\u003e-phases in the quasi-2D perovskite framework. By increasing the IPA volume to 500 \u003cem\u003e\u0026micro;l\u003c/em\u003e, the characteristic low \u003cem\u003en\u003c/em\u003e-phase diffraction peak at 3.2\u0026deg; is successfully eliminated, yielding a film dominated by higher \u003cem\u003en\u003c/em\u003e-phases with superior crystallinity and preferred orientation, as evidenced by the intensified (100) and (200) reflections.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e3.2. Optical Properties of Phase-Controlled Quasi-2D Perovskite Thin Films\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eTo further corroborate the phase evolution observed in XRD, UV-visible absorption and photoluminescence (PL) spectra were analyzed, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. The optical data clearly demonstrate a systematic transition in the dimension of the perovskite phases upon IPA treatment. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(a), the absorption spectrum of the pristine film exhibits multiple distinct excitonic absorption peaks in the short wavelength region (\u0026lt;\u0026thinsp;500 nm), which are characteristic of lower \u003cem\u003en\u003c/em\u003e-quasi-2D phases (\u003cem\u003en\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;2). As the IPA content increases from 100 to 500 \u003cem\u003e\u0026micro;l\u003c/em\u003e, the intensity of these excitonic peaks corresponding to the lower \u003cem\u003en\u003c/em\u003e-phases significantly diminishes. This trend indicates a reduction in the population of lower \u003cem\u003en\u003c/em\u003e-phases, consistent with the disappearance of the XRD peaks corresponding to these phases. The PL spectra also show a dominant emission peak with a noticeable redshift and increased intensity upon IPA treatment, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(b). The pristine thin film exhibits a relatively weak emission peak centered at 508 nm. Upon increasing the IPA treatment volume to 500 \u003cem\u003e\u0026micro;l\u003c/em\u003e, the PL peak shifts to 515 nm, which is associated with the emission from higher \u003cem\u003en\u003c/em\u003e-phases and 3D-like domains. The PL intensity increases remarkably, suggesting that the IPA treatment reduces non-radiative recombination centers by improving the crystallinity and optimizing the energy landscape. The narrow PL peak at 515 nm, despite the presence of multiple phases in the absorption spectra, confirms efficient energy funneling. The photogenerated excitons are effectively transferred from lower to higher \u003cem\u003en\u003c/em\u003e-phases with smaller bandgap energy before radiative recombination. The observed optical changes are driven by the solvent-engineered phase homogenization. The volatile antisolvent treatment disrupts the rapid and disordered precipitation of PEA-rich lower \u003cem\u003en\u003c/em\u003e-phases during the spin-coating process. By modulating the solubility of the precursor components, IPA facilitates the growth of larger \u003cem\u003en\u003c/em\u003e-domains. In quasi-2D perovskites, a graded energy landscape can be formed. The reduction of excessive lower \u003cem\u003en\u003c/em\u003e-phases and the enhanced formation of higher \u003cem\u003en\u003c/em\u003e-phases create a more efficient path for charge carriers, because these two act as energy barriers and energy sinks, respectively [11\u0026ndash;13]. In addition, the IPA treatment facilitates the removal of surface defects and unreacted species, leading to increased PL intensity and a clearer, more saturated green emission observed in the inset images. Therefore, the optical characterization by absorption and PL spectroscopy confirms successful phase modulation in PEA\u003csub\u003e2\u003c/sub\u003e(FA\u003csub\u003e0.7\u003c/sub\u003eCs\u003csub\u003e0.3\u003c/sub\u003e)\u003csub\u003en-1\u003c/sub\u003ePb\u003csub\u003en\u003c/sub\u003eBr\u003csub\u003e3n+1\u003c/sub\u003e films based on the IPA antisolvent treatment. The IPA treatment effectively suppresses the formation of lower-n phases, as evidenced by the diminished excitonic absorption peaks, while simultaneously enhancing PL emission in higher \u003cem\u003en\u003c/em\u003e-domains. These results, combined with the structural transition observed in XRD, demonstrate that volatile antisolvent engineering is a critical strategy for achieving high-purity, high-crystallinity quasi-2D perovskite films with optimized energy funneling for efficient optoelectronic applications.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTo further elucidate the effect of IPA treatment on the radiative recombination and charge carrier dynamics, time-resolved PL (TRPL) and PL quantum yield (PLQY) measurements were conducted. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(a), the PL decay curves for all samples exhibit similar exponential decay profiles. The average PL lifetime (\u003cem\u003eτ\u003c/em\u003e\u003csub\u003e\u003cem\u003eavg\u003c/em\u003e\u003c/sub\u003e) shows minor variations. The average PL lifetime increases from 2.8 ns (Pristine) to 4.43 ns (100 \u003cem\u003e\u0026micro;l\u003c/em\u003e), then decreases to its minimum of 2.07 ns (300 \u003cem\u003e\u0026micro;l\u003c/em\u003e), before slightly recovering to 4.51 ns (500 \u003cem\u003e\u0026micro;l\u003c/em\u003e). The relatively short lifetime at 300 \u003cem\u003e\u0026micro;l\u003c/em\u003e suggests a faster recombination process. Combined with the lower PLQY results, this may indicate an increase in non-radiative recombination pathways or an accelerated energy transfer process that is not efficiently coupled to radiative emission. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(b) and (c) show that the PL intensity and PLQY are highly sensitive to the IPA volume. The 100 \u003cem\u003e\u0026micro;l\u003c/em\u003e of IPA-treated film shows the highest PLQY, outperforming the pristine one. This enhancement is attributed to an optimized balance of quasi-2D phases, in which an appropriate amount of lower \u003cem\u003en\u003c/em\u003e-phases remains to facilitate efficient energy funneling to the higher \u003cem\u003en\u003c/em\u003e-emissive states. However, a significant reduction in PLQY is observed as the IPA volume exceeds 300 \u003cem\u003e\u0026micro;l\u003c/em\u003e. Specifically, the 500 \u003cem\u003e\u0026micro;l\u003c/em\u003e sample shows the lowest PLQY, despite exhibiting high crystallinity in XRD. The non-monotonic behavior of PLQY regarding IPA volume can be explained by the trade-off between phase purity and film quality. At 100 \u003cem\u003e\u0026micro;l\u003c/em\u003e, the IPA treatment moderately reduces the insulating lower \u003cem\u003en\u003c/em\u003e-phases while maintaining sufficient energy cascade from lower to higher \u003cem\u003en\u003c/em\u003e-phases. This moderate phase distribution minimizes energy loss during charge transfer prior to recombination, thereby improving radiative recombination at the emissive centers. As confirmed by XRD and UV-visible absorption data, the antisolvent treatment with IPA volumes above 300 \u003cem\u003e\u0026micro;l\u003c/em\u003e leads to the near-complete disappearance of the lower \u003cem\u003en\u003c/em\u003e-phases. The absence of these donor phases disrupts the energy-funneling mechanism, thereby decreasing PLQY. The drastic reduction in PLQY at high IPA contents may also stem from solvent-induced morphological defects. Excessive volatile antisolvent can cause rapid and aggressive crystallization, potentially leading to increased surface roughness or to the formation of pinholes and grain-boundary defects that act as non-radiative recombination centers. Therefore, the TRPL and PLQY analyses reveal that although IPA treatment is effective for phase modulation, its volume must be precisely controlled to optimize emission efficiency. In this study, a 100 \u003cem\u003e\u0026micro;l\u003c/em\u003e IPA treatment provides the ideal phase distribution for maximum PLQY through efficient energy funneling. Conversely, excessive IPA treatment (\u0026gt;\u0026thinsp;300 \u003cem\u003e\u0026micro;l\u003c/em\u003e) results in a significant reduction in emission efficiency due to excessive suppression of lower \u003cem\u003en\u003c/em\u003e-phases and a possible increase in non-radiative recombination centers caused by deteriorating film quality.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e3.3. Performances of LEDs based on Phase-Controlled Quasi-2D Perovskites\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eTo evaluate the practical application of the phase-engineered quasi-2D perovskite films, green LEDs were fabricated with the architecture shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e(a). The device consists of a multi-layered structure: ITO/PEDOT:PSS/PVP/quasi-2D perovskite/TPBi/LiF/Al. The energy band diagram, constructed from literature values, illustrates a well-aligned cascade that enables efficient charge injection into the perovskite emissive layer (EML). The external quantum efficiency (EQE) results for the LEDs treated by various amounts of IPA are presented as a function of current density, as shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e(b)-(e). The pristine device exhibits a relatively low peak EQE of 3.9%, attributed to excessive insulating spacer ligands and lower \u003cem\u003en\u003c/em\u003e-phases, which act as non-radiative recombination centers, as proven by previous XRD and PLQY analyses. Upon treatment with 100 \u003cem\u003e\u0026micro;l\u003c/em\u003e of IPA, the LED shows a remarkable peak EQE of 19.2%, a nearly fivefold improvement over the pristine device. This indicates that the optimized phase redistribution and enhanced crystallinity significantly improve the radiative recombination efficiency of the LED device. The EQE curves for 8 individual pixels per sample show high consistency and minimal deviation, demonstrating the excellent reproducibility and uniformity of the volatile antisolvent-assisted crystallization process. The superior performance of the 100 \u003cem\u003e\u0026micro;l\u003c/em\u003e IPA-treated device can be explained by the combined effects of balanced charge injection and funneling, reduced leakage current, and efficiency roll-off at high IPA concentrations. Most of all, the 100 \u003cem\u003e\u0026micro;l\u003c/em\u003e IPA treatment optimizes the populations of the lower and higher \u003cem\u003en\u003c/em\u003e-phases, which act as donor- and acceptor-like energy states in the EML, respectively. This promotes an efficient energy-funneling process, in which injected electrons and holes are concentrated in the most radiative higher \u003cem\u003en\u003c/em\u003e-domains, thereby maximizing the LED outputs. In addition, the improved film morphology and crystallinity, as confirmed by XRD measurements, reduce grain boundary defects. This effectively suppresses leakage current and non-radiative Shunt paths, leading to a steep increase in EQE at low current densities. Finally, for the LEDs treated with 300 and 500 \u003cem\u003e\u0026micro;l\u003c/em\u003e of IPA, the peak EQE values drop significantly. This trend is consistent with the PLQY results, in which the over-suppression of lower \u003cem\u003en\u003c/em\u003e-phases and the degradation of quasi-2D perovskite thin films hinder effective exciton formation and radiative decay. In this way, integrating IPA-treated quasi-2D perovskite films into green LEDs led to a substantial enhancement in device performance.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe electrical properties and operational stability of the quasi-2D perovskite LEDs were systematically investigated to elucidate the impact of IPA-induced phase modulation on device performance. As shown in the current density-voltage-luminance (\u003cem\u003eJ-V-L\u003c/em\u003e) characteristics (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ef), the IPA-treated devices exhibit a significantly lower leakage current in the sub-threshold low-voltage region compared to the pristine one. This suppression of leakage current suggests that the improved crystallinity and smooth morphology of the IPA-engineered films effectively passivate non-radiative shunt paths, which are typically prevalent in disordered quasi-2D systems. The luminance profiles exhibit a substantial enhancement upon IPA treatment. Notably, the 100 \u003cem\u003e\u0026micro;l\u003c/em\u003e IPA-treated device demonstrates the highest peak luminance and a reduced turn-on voltage. This improvement indicates enhanced charge injection and more efficient radiative recombination, enabled by the optimized quasi-2D energy cascade that directs excitons toward the most radiatively emissive centers. Interestingly, as the IPA volume increases to 500 \u003cem\u003e\u0026micro;l\u003c/em\u003e, a slight decrease in current density is observed at equivalent voltages. This trend correlates with the removal of the highly conductive lower \u003cem\u003en\u003c/em\u003e-phases and an increase in grain size, as previously confirmed by XRD, which collectively alter the charge transport kinetics within the EML.\u003c/p\u003e \u003cp\u003eThe operational stability of the optimized device (100 \u003cem\u003e\u0026micro;l\u003c/em\u003e IPA) was evaluated under a constant current density of 0.7 mA/cm\u0026sup2; with an initial luminance (\u003cem\u003eL\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e) of 1,026 cd/m\u0026sup2;. The device yielded a half-lifetime (\u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003e50\u003c/em\u003e\u003c/sub\u003e) of 4 minutes, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e(g). While quasi-2D perovskites inherently face stability challenges under high-brightness operation, the observed decay profile likely reflects intrinsic ion migration and Joule heating during continuous bias [20]. The superior performance of the 100 \u003cem\u003e\u0026micro;l\u003c/em\u003e IPA-treated device is attributed to optimized charge-injection balance, suppression of non-radiative recombination, and enhanced morphological integrity. By refining the phase distribution, the 100 \u003cem\u003e\u0026micro;l\u003c/em\u003e IPA treatment minimizes energetic disorder, thereby promoting balanced electron and hole injection. Furthermore, the dramatic increase in EQE from 3.9 to 19.2% is a direct consequence of reducing the population of defective lower \u003cem\u003en\u003c/em\u003e-phases. This structural refinement suppresses trap-mediated non-radiative recombination, allowing a larger fraction of excitons to decay radiatively at the higher \u003cem\u003en\u003c/em\u003e emission centers. The \u003cem\u003eJ-V\u003c/em\u003e characteristics further confirm that volatile antisolvent engineering promotes the formation of a denser and pinhole-free film, which is critical for sustaining high luminance at high bias without electrical breakdown. Therefore, these results demonstrate that precise control of the phase distribution via volatile antisolvent treatment not only maximizes the quantum efficiency but also optimizes the electrical driving conditions. This study provides a robust strategy for optimizing energy landscapes in multi-dimensional perovskite systems by offering a comprehensive pathway toward high-performance optoelectronic applications.\u003c/p\u003e \u003c/div\u003e"},{"header":"4. Conclusions","content":"\u003cp\u003eIn summary, we have successfully developed high-efficiency green LEDs by employing a volatile antisolvent treatment to engineer the phase redistribution of quasi-2D perovskites. The structural and optical investigations confirmed that the IPA treatment played a critical role in determining the emission properties of the PEA\u003csub\u003e2\u003c/sub\u003e(FA\u003csub\u003e0.7\u003c/sub\u003eCs\u003csub\u003e0.3\u003c/sub\u003e)\u003csub\u003en\u0026minus;1\u003c/sub\u003ePb\u003csub\u003en\u003c/sub\u003eBr\u003csub\u003e3n+1\u003c/sub\u003e quasi-2D perovskite thin films. The introduction of 100 \u003cem\u003e\u0026micro;l\u003c/em\u003e of IPA effectively eliminated the parasitic lower \u003cem\u003en\u003c/em\u003e-phases, thereby facilitating an optimized energy cascade from lower \u003cem\u003en\u003c/em\u003e- to larger \u003cem\u003en\u003c/em\u003e-phases. This structural refinement resulted in a record-level EQE of 19.2% with high reproducibility across multiple pixels. Although the device stability showed a \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003e50\u003c/em\u003e\u003c/sub\u003e of 4 minutes at a high initial luminance of 1,026 cd/m\u003csup\u003e2\u003c/sup\u003e, the significant enhancements in radiative and charge injection efficiencies represented a substantial step forward. These findings provide valuable insights into the crystallization kinetics of multi-dimensional perovskites and offer a promising pathway for developing high-performance emissive layers for advanced display and lighting applications.\u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eCRediT authorship contribution statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eS.-B. Cho\u003c/strong\u003e: Writing-original draft, Conceptualization, Writing-review, Methodology. \u003cstrong\u003eJ.-H. Kim\u003c/strong\u003e: Data curation, Resources, Investigation, Formal analysis, Writing-review, Methodology, \u003cstrong\u003eC.-X. Li\u003c/strong\u003e: Data curation, Investigation, Formal analysis, Methodology, \u003cstrong\u003eI.-K. Park\u003c/strong\u003e: Supervision, Resources, Project administration, editing, Funding acquisition.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDeclaration of Competing Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by the Research program funded by the Seoultech (Seoul National University of Science \u0026amp; Technology).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eK. Lin, J. Xing, L. N. Quan, F. P. G. de Arquer, X. Gong, J. Lu, L. Xie, W. Zhao, D. Zhang, C. Yan, W. Li, X. Liu, Y. Lu, J. Kirman, E. H. Sargent, Q. Xiong and Z. Wei, Nature, 562, 245 (2018).\u003c/li\u003e\n\u003cli\u003eY.-H. Kim, S. Kim, A. Kakekhani, J. Park, J. 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Cho, E. Ercan, C.C. Chueh, W.C. Chen, R. Borsali and C.C. Kuo, ACS Omega, 5, 8972 (2020). \u003c/li\u003e\n\u003cli\u003eA. Ali, S. Oh, W. Kim and S. J. Oh, Korean J. Chem. Eng. 41, 3545 (2024).\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"korean-journal-of-chemical-engineering","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"kjce","sideBox":"Learn more about [Korean Journal of Chemical Engineering](http://link.springer.com/journal/11814)","snPcode":"11814","submissionUrl":"https://www.editorialmanager.com/kjce/default2.aspx","title":"Korean Journal of Chemical Engineering","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Subscription","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Quasi-2D, Perovskite, Antisolvent, Post-treatment, Light-Emitting Diode, External quantum efficiency","lastPublishedDoi":"10.21203/rs.3.rs-9167259/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9167259/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eQuasi-two-dimensional (quasi-2D) perovskites have emerged as promising candidates for high-performance light-emitting diodes (LEDs) due to their unique energy funneling mechanism. However, uncontrollable phase distribution during film crystallization often leads to excessive formation of lower \u003cem\u003en\u003c/em\u003e-phases, which hinder efficient charge transport and radiative recombination. In this study, we demonstrate a facile and effective strategy to modulate the phase distribution and crystallinity of quasi-2D perovskite PEA\u003csub\u003e2\u003c/sub\u003e(FA\u003csub\u003e0.7\u003c/sub\u003eCs\u003csub\u003e0.3\u003c/sub\u003e)\u003csub\u003en\u0026minus;1\u003c/sub\u003ePb\u003csub\u003en\u003c/sub\u003eBr\u003csub\u003e3n+1\u003c/sub\u003e thin films using a volatile antisolvent, isopropyl alcohol (IPA). Structural and optical investigations revealed that the IPA treatment effectively suppressed the insulating lower \u003cem\u003en\u003c/em\u003e-phases (\u003cem\u003en\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;2) and promoted the growth of higher \u003cem\u003en\u003c/em\u003e-domains (\u003cem\u003en\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;3). Optimized IPA treatment of 100 \u003cem\u003e\u0026micro;l\u003c/em\u003e yields a high photoluminescence quantum yield and balanced energy funneling, whereas excessive IPA (\u0026gt;\u0026thinsp;300 \u003cem\u003e\u0026micro;l\u003c/em\u003e) leads to phase oversimplification and morphological defects. Consequently, the green LED fabricated with 100 \u003cem\u003e\u0026micro;l\u003c/em\u003e of IPA-treated emissive layer achieved a remarkable peak external quantum efficiency of 19.2% and high luminance, representing a nearly fivefold improvement over the pristine device. This work verifies the critical role of volatile antisolvent engineering in tailoring the energy landscape for high-efficiency perovskite optoelectronics.\u003c/p\u003e","manuscriptTitle":"Performance Enhancement of Quasi-2D Perovskite Light-Emitting Diodes Based on Phase Control by Volatile Antisolvent Treatment","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-30 15:57:26","doi":"10.21203/rs.3.rs-9167259/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2026-03-27T01:12:19+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-27T01:10:51+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-25T12:58:38+00:00","index":"","fulltext":""},{"type":"submitted","content":"Korean Journal of Chemical Engineering","date":"2026-03-19T04:52:50+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"korean-journal-of-chemical-engineering","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"kjce","sideBox":"Learn more about [Korean Journal of Chemical Engineering](http://link.springer.com/journal/11814)","snPcode":"11814","submissionUrl":"https://www.editorialmanager.com/kjce/default2.aspx","title":"Korean Journal of Chemical Engineering","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Subscription","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"3dea4652-39a2-41ec-abc0-6f829dd7ab53","owner":[],"postedDate":"March 30th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-03-30T15:57:27+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-30 15:57:26","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9167259","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9167259","identity":"rs-9167259","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}