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Modulating the luminance of organic light-emitting diodes via optical stimulation of a photochromic molecular monolayer at transparent oxide electrode
摘要： Self-assembled monolayers (SAMs) deposited on bottom electrodes are commonly used to tune charge carrier injection or blocking in optoelectronic devices. Beside the enhancement of device performance, the fabrication of multifunctional devices in which the output can be modulated by multiple external stimuli remains a challenging target. In this work, we report the functionalization of an indium tin oxide (ITO) electrode with a SAM of a diarylethene derivative designed for optically control the electronic properties. Following the demonstration of dense SAM formation and its photochromic activity, as a proof-of-principle, an organic light-emitting diode (OLED) embedding the light-responsive SAM-covered electrode was fabricated and characterized. Optically addressing the two-terminal device by irradiation with ultraviolet light doubles the electroluminescence. The original value can be restored reversibly by irradiation with visible light. This expanded functionality is based on the photoinduced modulation of the electronic structure of the diarylethene isomers, which impact the charge carriers’ confinement within the emissive layer. This approach could be successfully exploited in the field of opto-communication technology, for example to fabricate opto-electronic logic circuits.
关键词： photochromic,optoelectronic devices,diarylethene,Self-assembled monolayers,organic light-emitting diodes
更新于2025-09-19 17:13:59
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Hydrothermal growth of n-ZnO films on a patterned p-GaN epilayer and its application in heterojunction light-emitting diodes
摘要： The hydrothermal growth (HTG) of crystalline n-ZnO ?lms on both the nonpatterned and patterned p-GaN epilayers with a honeycomb array of etched holes is demonstrated, and its application in n-ZnO/p-GaN heterojunction light-emitting diodes (HJ-LEDs) is reported. The results reveal that an HTG n-ZnO ?lm on a patterned p-GaN layer exhibits a high-quality single crystal with FWHMs of 0.463 and 0.983° obtained from a ω-rocking curve and a ?-scan pattern, respectively, which are much better than those obtained on a nonpatterned p-GaN layer. In addition, the n-ZnO/patterned p-GaN HJ-LED exhibited a much better rectifying diode behavior owing to having a higher n-ZnO ?lm crystallinity quality and an improved interface with the p-GaN layer. Strong violet and violet-blue lights emitted from the n-ZnO/patterned p-GaN HJ-LED at around 405, 412, and 430 nm were analyzed.
关键词： crystallinity quality,n-ZnO films,heterojunction light-emitting diodes,hydrothermal growth,p-GaN epilayer
更新于2025-09-19 17:13:59
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White-emitting protein-metal nanocluster phosphors for highly performing bio-hybrid light-emitting diodes
摘要： This work presents a simple in-situ synthesis and stabilization of fluorescent gold nanoclusters (AuNCs) with different sizes using engineered protein scaffolds in water. The protein-AuNC hybrids show a dual emission (450 and 700 nm) with a record photoluminescence quantum yield of 20%. These features impelled us to apply them to bio-hybrid light-emitting diodes (Bio-HLEDs) as color down-converting filters or bio-phosphors. Efficient white emission (x/y CIE color coordinates of 0.31/0.29) and stabilities of >800 h were achieved. This represents a two orders of magnitude enhancement compared to the prior art. Besides the outstanding performance, the protein scaffold also infers a unique anisotropic emission character that is considered as a proof-of-concept of high interest for single-point lighting and display.
关键词： bio-phosphors,protein design,Light-emitting diodes,repeat proteins,bio-hybrid materials,metal nanocluster
更新于2025-09-19 17:13:59
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Nanosecond-time-scale delayed fluorescence molecule for deep-blue OLEDs with small efficiency rolloff
摘要： Aromatic organic deep-blue emitters that exhibit thermally activated delayed fluorescence (TADF) can harvest all excitons in electrically generated singlets and triplets as light emission. However, blue TADF emitters generally have long exciton lifetimes, leading to severe efficiency decrease, i.e., rolloff, at high current density and luminance by exciton annihilations in organic light-emitting diodes (OLEDs). Here, we report a deep-blue TADF emitter employing simple molecular design, in which an activation energy as well as spin–orbit coupling between excited states with different spin multiplicities, were simultaneously controlled. An extremely fast exciton lifetime of 750 ns was realized in a donor–acceptor-type molecular structure without heavy metal elements. An OLED utilizing this TADF emitter displayed deep-blue electroluminescence (EL) with CIE chromaticity coordinates of (0.14, 0.18) and a high maximum EL quantum efficiency of 20.7%. Further, the high maximum efficiency were retained to be 20.2% and 17.4% even at high luminance.
关键词： deep-blue OLEDs,organic light-emitting diodes (OLEDs),small efficiency rolloff,Nanosecond-time-scale delayed fluorescence,thermally activated delayed fluorescence (TADF)
更新于2025-09-19 17:13:59
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High-efficiency near-infrared fluorescent organic light-emitting diodes with small efficiency roll-off based on AIE-active phenanthro[9,10- <i>d</i> ]imidazole derivatives
摘要： The simultaneous realization of high-efficiency and low-cost in fluorescent organic light-emitting diodes (OLEDs) is still a formidable challenge in deep-red (DR)/near-infrared (NIR) region because of the intrinsic limitation of the energy-gap law and fluorescence quenching effect. Herein, three novel donor-acceptor-donor′ (D-A-D′) fluorophores, PIBz-10-PTZ, PIBz-10P-PTZ and PIBz-3-PTZ, by utilizing phenanthro[9,10-d]imidazole and phenothiazine as the donor, benzothiadiazole as the acceptor are synthesized. Owing to the unilateral steric hindrance between adjacent hydrogen atoms along the horizontal axis, PIBz-3-PTZ possesses a completely planar conformation and fully conjugated structure. PIBz-3-PTZ exhibits a strong DR emission and aggregation induced emission (AIE) property with a high photoluminescence quantum yield of 35% in neat thin film. The nondoped OLEDs achieved a maximum external quantum efficiency (EQE) of 2.02% with an emission peak at 672 nm and the brightness of up to 3403 cd m-2. In addition, the device was able to maintain an EQE of 1.69% at high luminance of 100 cd m-2, with a low efficiency roll-off of 16%, suggesting the nondoped device can keep the brightness.
关键词： Near-Infrared,High-Efficiency,AIE-active,Phenanthro[9,10-d]imidazole Derivatives,Organic Light-Emitting Diodes,Small Efficiency Roll-Off,Fluorescent
更新于2025-09-19 17:13:59
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Mid-infrared Polarized Emission from Black Phosphorus Light-Emitting Diodes
摘要： We demonstrate a mid-infrared light-emitting diode based on the 2D semiconductor black phosphorus (BP). The device is composed of a mechanically exfoliated BP/molybdenum disulfide heterojunction. Under forward bias, it emits polarized electroluminescence at λ = 3.68 μm, with room-temperature internal and external quantum efficiencies of ~1% and ~0.03%, respectively. In our structure, outcoupling losses are dominated by radiation towards the high refractive index substrate. The ability to tune the bandgap of BP, and consequently its emission wavelength with layer number, strain and electric field make these LEDs particularly attractive for heterointegration into mid-infrared photonic platforms.
关键词： heterostructures,2D materials,mid-infrared emitters,light-emitting diodes,Black phosphorus
更新于2025-09-19 17:13:59
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Enhancing Charge Carrier Delocalization in Perovskite Quantum Dot Solids with Energetically Aligned Conjugated Capping Ligands
摘要： Compared to bulk perovskites, charge transport in perovskite quantum dot (PQD) solids is limited. To address this issue, energetically aligned capping ligands were used to prepare methylammonium lead bromide (MAPbBr3) PQDs towards enhancing surface charge carrier density in PQD solids. Trans-cinnamic acid (TCA) and its derivates, functionalized with electron-donating or electron-withdrawing groups to modulate energy levels, are used as passivating exciton-delocalizing ligands (EDLs) to decrease the energy gap with respect to the PQD core. 3,3-diphenylpropylamine (DPPA) ligand is shown to stabilize EDLs on the PQD surface through π-π stacking intermolecular interaction, mitigating charge trapping and non-radiative decay. Passivation using EDLs in combination with DPPA increases the photoluminescence (PL) quantum yield (QY) (90%), photoconductivity, extraction, mobility, transport time, and lifetime of charge carriers in PQD solids. Prototype PQD-based light-emitting diodes (LEDs) were demonstrated with a low turn-on voltage of 2.5 V.
关键词： charge transport,light-emitting diodes,capping ligands,perovskite quantum dots,photoluminescence
更新于2025-09-19 17:13:59
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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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All-solution Processed High Performance Inverted Quantum Dot Light Emitting Diodes
摘要： All-solution processed colloidal quantum dot light emitting diodes (QLEDs) with record performance have been successfully realized by introducing dually-doped poly(ethylenedioxythiophene)/polystyrenesulfonate (PEDOT:PSS) hole-injection layer and polyethylenimine (PEI) interfacial layer. Doping PEDOT:PSS with both Zonyl and isopropanol (IPA) significantly improves the wettability of PEDOT:PSS, making coating hydrophilic PEDOT:PSS onto hydrophobic hole-transporting layer poly(9-vinlycarbazole) (PVK) possible. The PEI interlayer between PVK/QD layer not only lowers down the vacuum level, thereby reducing the hole-injection barrier to balance the charge carriers, but also passivates QD surface defects via its amine group to suppress fluorescence quenching. As a result, the peak current efficiency of 28.1 cd/A, 43.1 cd/A, and 1.26 cd/A, the maximum external quantum efficiency (EQE) of 20.6%, 10.4%, and 2.95%, and the maximum luminance of 5.06 × 104 cd/m2, 1.21 × 105 cd/m2, and 2.96 × 103 cd/m2, have been achieved for red, green, and blue QLEDs, respectively. To the best of our knowledge, the red device’s EQE is one of the highest among all inverted red QLEDs. In addition, the extrapolated lifetime of the red QLEDs sets a new record by reaching 8253 h at an initial brightness of 100 cd/m2.
关键词： PEDOT:PSS,inverted structure,QLEDs,all-solution processed,quantum dot light emitting diodes,PEI
更新于2025-09-19 17:13:59
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Improved Charge Injection and Transport of Light-Emitting Diodes Based on Two-Dimensional Materials
摘要： Light-emitting diodes (LEDs) are considered to be the most promising energy-saving technology for future lighting and display. Two-dimensional (2D) materials, a class of materials comprised of monolayer or few layers of atoms (or unit cells), have attracted much attention in recent years, due to their unique physical and chemical properties. Here, we summarize the recent advances on the applications of 2D materials for improving the performance of LEDs, including organic light emitting diodes (OLEDs), quantum dot light emitting diodes (QLEDs) and perovskite light emitting diodes (PeLEDs), using organic ?lms, quantum dots and perovskite ?lms as emission layers (EMLs), respectively. Two dimensional materials, including graphene and its derivatives and transition metal dichalcogenides (TMDs), can be employed as interlayers and dopant in composite functional layers for high-e?ciency LEDs, suggesting the extensive application in LEDs. The functions of 2D materials used in LEDs include the improved work function, e?ective electron blocking, suppressed exciton quenching and reduced surface roughness. The potential application of 2D materials in PeLEDs is also presented and analyzed.
关键词： perovskite light emitting diodes,quantum dot light emitting diodes,organic light emitting diodes,two-dimensional materials
更新于2025-09-16 10:30:52