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Increased luminescent efficiency of perovskite light emitting diodes based on modified two-step deposition method providing gradient concentration
摘要： We increased the luminescent efficiency of perovskite light-emitting diodes (PeLEDs) by using a modified two-step deposition method combined with an interdiffusion process without additional solvent engineering or additive molecules. Methylammonium lead bromide (MAPbBr3) polycrystalline films with nanosized grains and low electronic disorder were fabricated by a modified two-step deposition process. The as-fabricated MAPbBr3 films showed gradient concentration characteristics as a result of a gradient distribution of the MABr. Also, the MABr-gradient concentration structure was intensified by the interdiffusion process, showing improved performance of MAPbBr3 PeLEDs with maximum current efficiency CEmax = 0.861 cd A?1 and maximum luminance = 604 cd m?2 with very narrow electroluminescence spectral width. This is the highest CEmax among MAPbBr3-based PeLEDs deposited by the two-step deposition method.
关键词： two-step deposition method,perovskite light-emitting diodes,luminescent efficiency,gradient concentration,interdiffusion process
更新于2025-09-23 15:21:21
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Rational Interface Engineering for Efficient Flexible Perovskite Light-Emitting Diodes
摘要： Although perovskite light-emitting diodes (Pe-LEDs) are promising for next-generation displays and lighting, their efficiency is still considerably below that of conventional inorganic and organic counterparts. Significant efforts in various aspects of the electroluminescence process are required to achieve high-performance PeLEDs. Here, we present an improved flexible PeLED structure based on the rational interface engineering for energy-efficient photon generation and enhanced light outcoupling. The interface-stimulated crystallization and defect passivation of the perovskite emitter are synergistically realized by tuning the underlying interlayer, leading to the suppression of trap-mediated nonradiative recombination losses. Besides approaching highly emissive perovskite layers, the outcoupling of trapped light is also enhanced by combining the silver nanowires-based electrode with quasi-random nanopatterns on flexible plastic substrate. Upon the collective optimization of the device structure, a record external quantum efficiency of 24.5% is achieved for flexible PeLEDs based on green-emitting CsPbBr3 perovskite.
关键词： defect passivation,flexible perovskite light-emitting diodes,perovskite light-emitting diodes,silver nanowires,light outcoupling
更新于2025-09-23 15:21:01
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Boosting the Efficiency and Curtailing the Efficiency Roll-off in Green Perovskite Light-Emitting Diodes via Incorporating Ytterbium as Cathode Interface Layer
摘要： Perovskite light-emitting diodes (PeLEDs) exhibit high external quantum efficiencies (EQEs), emerging as a next-generation technology for lighting and display applications. Nevertheless, they suffer from severe efficiency roll-off at high luminance, particularly in case of blue and green emissions, which is one of the major bottlenecks in their industrial applications. Here, we attack this problem using a rare-earth metal, Yb, as cathode interface layer (CIL) for green PeLEDs. By adopting a new device configuration of ITO/TFB/FA-based Quasi-2D Perovskite/TPBi/Yb/Ag, we achieved a peak current efficiency (CE) of 22.3 cd/A with a corresponding EQE of 5.28% and a high maximum luminance of 19,160 cd/m2. Importantly, the maximum CE of 22 cd/A at 2,000 cd/m2 slightly decreased to 16.8 cd/A at 5,000 cd/m2 and maintained a still decent value of 12 cd/A at a very high luminance of 10,000 cd/m2, exhibiting a remarkably low efficiency roll-off. Our Yb-incorporated devices significantly outperformed the PeLEDs containing conventional CILs, including Mg and Liq, in terms of peak efficiency, efficiency roll-off and operational lifetime. We attribute this encouraging performance to barrier-free, efficient electron injection enabled by the low work function of Yb (2.6 eV) which led to a high electron current, nearly approaching the hole current in hole-dominant PeLEDs, as confirmed by the single-carrier device measurements. In addition, we also present Yb-incorporated PeLEDs containing Cs-based Quasi-2D perovskite as the emissive layer which displayed an impressive CE of 51.3 cd/A with a corresponding EQE of 16.4% and a maximum luminance of 14,240 cd/m2, and still demonstrated a reduced efficiency roll-off comparing to that of the Liq-based equivalent. These results unveil the inspiring prospects of Yb as an efficient CIL for PeLEDs towards high efficiency with reduced efficiency roll-off.
关键词： electron injection,ytterbium,quasi-2D,perovskite light-emitting diodes,stability,cathode interface layer,efficiency roll-off
更新于2025-09-23 15:21:01
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Ultra-High Vacuum Annealing-Assisted Quantum Wells Dimensional Tailoring for Perovskite Light-Emitting Diodes Efficiency Enhancement
摘要： Quasi-two-dimensional (Q-2D) perovskites featured with multiple dimensional quantum wells (QWs) have been the main candidates for optoelectronic applications. However, the excessive low-dimensional perovskite is unfavorable to the device efficiency due to the phonon-exciton interaction and the inclusion of insulating large organic cation. Herein, the low-dimensional QWs formation is suppressed by removing the organic cation 1-naphthylmethylamine iodide (NMAI) through the ultra-high vacuum (UHV) annealing. The perovskite light-emitting diodes (PLEDs) devices based on films annealed with optimized UHV conditions show higher external quantum efficiency of 13.0% and wall-plug efficiency of 11.1% compared to otherwise identical devices with films annealed in a glovebox.
关键词： quantum wells,ultra-high vacuum annealing,dimensional tailoring,quasi-two-dimensional perovskites,perovskite light-emitting diodes
更新于2025-09-23 15:21:01
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Suppressing Efficiency Roll-Off at High Current Densities for Ultra-Bright Green Perovskite Light-Emitting Diodes
摘要： Perovskite light-emitting diodes (PeLEDs) have undergone rapid development in the last several years with external quantum efficiencies (EQE) reaching over 21%. However, most PeLEDs still suffer from severe efficiency roll-off (droop) at high injection current densities, thus limiting their achievable brightness and presenting a challenge to their use in laser diode applications. In this work, we show that the roll-off characteristics of PeLEDs are affected by a combination of charge injection imbalance, nonradiative Auger recombination, and Joule heating. To realize ultrabright and efficient PeLEDs, several strategies have been applied. First, we designed an energy ladder to balance the electron and hole transport. Second, we optimized perovskite materials to possess reduced Auger recombination rates and improved carrier mobility. Third, we replaced glass substrates with sapphire substrates to better dissipate joule heat. Finally, by applying a current-focusing architecture, we achieved PeLEDs with a record luminance of 7.6 Mcd/m2. The devices can be operated at very high current densities (J) up to ~ 1 kA/cm2. Our work suggests a broad application prospect of perovskite materials for high-brightness LEDs and ultimately a potential for solution-processed electrically pumped laser diodes.
关键词： Joule heat,efficiency roll-off,Auger recombination,charge injection balance,high injection current density,ultrahigh brightness,perovskite light emitting diodes
更新于2025-09-23 15:19:57
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High-performance green light-emitting diodes based on MAPbBr <sub/>3</sub> with ??-conjugated ligand
摘要： The morphology, crystal size, and trap density of perovskite films significantly affect the luminescent properties of perovskite light-emitting diodes (PeLEDs). Recently, numerous studies have been conducted on ligands that surround the surface of perovskite crystals and passivate the trap sites to improve the performance of PeLEDs. In this study, a 4-aminobenzonitrile (ABN) ligand improved the performance of methylammonium lead bromide (MAPbBr3)-based PeLEDs by reducing the MAPbBr3 crystal size to the nanoscale and reducing the trap density. Moreover, the properties of PeLEDs with ABN were further improved using a surface-modified hole-transport layer (HTL) with a hydrophilic polymer. Finally, a bright green PeLED was fabricated and exhibited the maximum luminance of 3350 cd/m2 with an external quantum efficiency of 8.85%. Therefore, it is believed that the use of proper ligands for the perovskite layer and the optimization of the charge-transport layer have great potential for the development of high-performance PeLEDs.
关键词： methylammonium lead bromide,hydrophilic polymer,conjugated ligand,surface-modified hole-transport layer,perovskite light-emitting diodes,4-aminobenzonitrile
更新于2025-09-23 15:19:57
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Ambient-Processed, Additive-Assisted CsPbBr3 Perovskite Light-Emitting Diodes with Colloidal NiOx Nanoparticles for Efficient Hole Transporting
摘要： In this study, the electrically driven perovskite light-emitting diodes (PeLEDs) were investigated by hybridizing the organic polyethylene oxide, 1,3,5-tris (N-phenylbenzimiazole-2-yl) benzene (TPBi), and bis(3,5-di?uoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl) iridium III (FIrpic) with CsPbBr3 in the emission layer and adopting the colloidal NiOx nanoparticle (NP) hole transport layer. The synthesized NiOx NPs, having an average size of ~5 nm, can be spin-coated to become a smooth and close-packed ?lm on the indium–tin–oxide anode. The NiOx NP layer possesses an overall transmittance of ~80% at 520 nm, which is about the peak position of electroluminescence (EL) spectra of CsPbBr3 emission layer. The coating procedures of NiOx NP and CsPbBr3 layers were carried out in ambient air. The novel PeLED turned on at 2.4 V and emitted bright EL of 4456 cd/m2 at 7 V, indicating the remarkable nonradiative-related defect elimination by organic additive addition and signi?cant charge balance achieved by the NiOx NP layer.
关键词： colloidal NiOx nanoparticles,organic additives,ambient-process,perovskite light-emitting diodes (PeLEDs),inorganic lead halide perovskites
更新于2025-09-23 15:19:57
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Perovskite-molecule composite thin films for efficient and stable light-emitting diodes
摘要： Although perovskite light-emitting diodes (PeLEDs) have recently experienced significant progress, there are only scattered reports of PeLEDs with both high efficiency and long operational stability, calling for additional strategies to address this challenge. Here, we develop perovskite-molecule composite thin films for efficient and stable PeLEDs. The perovskite-molecule composite thin films consist of in-situ formed high-quality perovskite nanocrystals embedded in the electron-transport molecular matrix, which controls nucleation process of perovskites, leading to PeLEDs with a peak external quantum efficiency of 17.3% and half-lifetime of approximately 100 h. In addition, we find that the device degradation mechanism at high driving voltages is different from that at low driving voltages. This work provides an effective strategy and deep understanding for achieving efficient and stable PeLEDs from both material and device perspectives.
关键词： perovskite light-emitting diodes,external quantum efficiency,perovskite-molecule composite thin films,operational stability
更新于2025-09-19 17:13:59
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Large-Area Cesium Lead Bromide Perovskite Light-Emitting Diodes Realized by Incorporating a Hybrid Additive
摘要： Encouraging progresses have been made in the development of solution processable perovskite light-emitting diodes (PeLEDs). However, the related fundamental physics of the efficient operation of the large area PeLEDs is still far from adequate. In this work, we report our recent effort in developing a high-performance large area cesium lead bromide (CsPbBr3) PeLEDs through a controlled growth of CsPbBr3 emission layer using a hybrid additive in the CsPbBr3 precursor solution. The hybrid additive comprises a combination of poly(ethylene oxide) (PEO) and cesium carbonate (Cs2CO3). We found that the performance of the CsPbBr3 PeLEDs, prepared using the precursor solution having a hybrid additive of PEO and Cs2CO3, is superior to that of the control PeLEDs, prepared using a pure CsPbBr3 precursor solution in two ways: (1) it helps to suppress both the structural defects and non-radiative recombination-induced leakage current, and (2) it assists in improving the electron-hole current balance. The 1.0×1.5 cm2-sized PeLEDs having a maximum luminance of > 104 cd/m2 has been demonstrated, which is more than three times greater than that of a control PeLED prepared using a pure CsPbBr3 precursor solution (3.0×103 cd/m2).
关键词： hybrid additive,cesium lead bromide,perovskite light-emitting diodes,large area
更新于2025-09-19 17:13:59
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Bright and Color-Stable Blue-Light-Emitting Diodes based on Three-Dimensional Perovskite Polycrystalline Films via Morphology and Interface Engineering
摘要： Substantial progress has been achieved in red and green perovskite light-emitting diodes (PeLEDs). However, blue PeLEDs are still inferior in light-emitting efficiency and luminance compared with their green and red counterparts. Herein efficient blue PeLEDs simultaneously achieving high luminance and high color stability are fabricated based on the polycrystalline perovskites with a 3D Rb?Cs alloyed scaffold. The synergistic manipulation of an isopropanol antisolvent treatment and the PEDOT:PSS/blue perovskite interface modification with RbCl effectively improve the photoluminescence properties of the resultant blue polycrystalline 3D perovskite films and the final electroluminescence performance of the blue PeLEDs. The optimized blue PeLEDs show a maximum external quantum efficiency of 1.66% with an emission peak at 484 nm and a full width at half-maximum of 18 nm as well as CIE coordinates of (0.08, 0.21). Moreover, the optimized blue PeLEDs not only show superior color stability under various luminances but also achieve high luminances. The obtained maximum luminance of 9243 cd m?2 is one of the highest values among the efficient and color-stable blue PeLEDs.
关键词： blue PeLEDs,perovskite light-emitting diodes,Rb?Cs alloyed scaffold,color stability,high luminance
更新于2025-09-19 17:13:59