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Polymer light emitting diodes (PLEDs): An update review on current innovation and performance of material properties
摘要： Conventional lighting systems, such as the incandescent light bulbs used on the offshore oil rigs are becoming obsolete due to high energy consumption, poor life span and additional costs of waste treatment and disposal. Furthermore, they are susceptible to fire when exposed to an oxygen rich environment, posing a threat to the oil rig workers. Recent advances have led to the development of polymer light emitting diodes (PLEDs) as substitutes to these prevailing light sources. The PLEDs have advantages over the incandescent bulbs, for being durable, low energy consumption and environmental friendly. Consequently, the increasing research collaborations among the academic researchers and industrial stakeholders are gaining momentum in ensuring the advancements of PLEDs in terms of economic value and performance. This paper is aimed at reviewing the recent advances in the field of current innovation and performance of PLEDs materials. The paper focuses on the important experiments on the PLEDs materials towards the upgrading and modification of anode and holes injection/transporting layer and the influence of doping effect. In spite of that, this paper discovered that synthetic materials, such as synthetic silicates are the commonly used materials in the current PLEDs, and recommends the incorporation of cost effective inorganic clay-polymer nanocomposite-based LEDs as a way forward to reducing the material costs and provide more environmental friendly PLEDs materials.
关键词： doping,insertion,Polymer light emitting diodes,intercalation,materials
更新于2025-09-12 10:27:22
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Cyclohexane-cored dendritic host materials with high triplet energy for efficient solution-processed blue thermally activated delayed fluorescence OLEDs
摘要： Two dendritic host materials (CH-2D1 and CH-2D2) are developed by using non-conjugated cyclohexane core and two first/second generation carbazole dendrons, which show excellent solubility in organic solvents, high thermal stability and high triplet energy (ET) of 2.78–2.84 eV, making them suitable for fabrication of solution-processed blue thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs). Compared to CH-2D1 with the first-generation carbazole dendron which shows low-lying highest occupied molecular orbital (HOMO) energy level of (cid:0) 5.48 eV, CH-2D2 with the second-generation carbazole dendrons exhibits higher HOMO level of (cid:0) 5.37 eV, which is more favourable for hole injection from the anode to the emissive layers. Consequently, solution-processed blue TADF OLEDs utilizing CH-2D2 as host show promising device performance with a low turn-on voltage of 3.4 V, maximum external quantum efficiency of 17.8%, (cid:0) 1, which can compare with the most efficient solution-processed blue TADF OLEDs based on small-molecule and polymer hosts. These results indicate that dendritic host materials with well-defined chemical structure and good solubility are an attractive approach–beyond the soluble small-molecule hosts and polymer hosts–for the development of efficient solution-processed TADF OLEDs.
关键词： Thermally activated delayed fluorescence,Dendritic host materials,Organic light-emitting diodes,High triplet energy
更新于2025-09-12 10:27:22
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Novel Bromide Quaternary Ammonium Ligand for Synthesizing High Fluorescence Efficiency CsPbBn Perovskite Quantum Dots and Their Fabrication of White Light-Emitting Diodes with Wide Color Gamut
摘要： We proposed a novel bromine quaternary ammonium ligand to synthesize high quantum yield (QY) CsPbBr3 quantum dots (QDs). The QY of CsPbBr3 QDs synthesized by this ligand reached 95% and the full width at half maximum (FWHM) was as narrow as 17nm. The peak wavelength of the prepared CsPbBr3 QDs was 530nm. And these QDs emitted high purity green light under ultraviolet light. The color coordinate of white LED (WLED) prepared with the CsPbBr3 QDs was (0.29, 0.31), which was very close to pure white light. The color gamut of the WLED covered 130% of the national television system committee (NTSC) color standard and 96% of the ITU-R Recommendation BT.2020 (Rec.2020) color standard.
关键词： CsPbBr3 Perovskite Quantum Dots,Bromide Quaternary Ammonium Ligand,Wide Color Gamut,White Light-Emitting Diodes
更新于2025-09-12 10:27:22
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Highly Efficient and Thermal-Stable QD-LEDs Based on Quantum Dots-SiO <sub/>2</sub> -BN Nanoplate Assemblies
摘要： Silica encapsulation effectively elevates the resistance of quantum dots (QDs) against water and oxygen. However, QDs-SiO2 composites present low thermal conductivity and strong thermal accumulation, leading to considerable fluorescent quenching of QDs in optoelectronic devices at high power. Here, a sandwich structural QDs-SiO2-BN nanoplate assembly material (QDs-SiO2-BNAs) is developed to reduce the thermal quenching and enhance the stability of QDs in LEDs. The QDs-SiO2-BNAs is fabricated by embedding QDs-SiO2 into the interlayer of layer-by-layer assembled BN nanoplates, and the BN nanoplates are pretreated by SiO2 encapsulation to strengthen the interaction with QDs-SiO2. This assembly structure endows the QDs with fast heat dissipation and double surface protection against air. The medium power QDs-converted LEDs (QD-LEDs) fabricated by directly on-chip packaging of the QDs-SiO2-BNAs gain 44.2 ℃ temperature reduction at 0.5 W in comparison with conventional QD-LEDs. After aging, the resulting QD-LEDs present degradation of only 1.2% under sustained driving for 250 hours. The QD-LEDs also pass the one-week reliability test at 85 ℃ / 85% RH with <±0.01 shift of the color coordinates, demonstrating the profound potential of the QDs-SiO2-BNAs in LED lighting and display applications.
关键词： stability,quantum dots,boron nitride,assembly,light-emitting diodes
更新于2025-09-12 10:27:22
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Perovskite light-emitting diodes for uniform eight-segment displays
摘要： With the development of the display technology, there are higher requirements for color saturation and vividness. As a base unit, light-emitting diode (LED) has become a primary object of study. Perovskite quantum dots with high photoluminescence quantum yield, narrow emission, and wide color gamut have attracted special attention in recent years. Although LEDs based on perovskite exhibit excellent performance, there are few applications of perovskite LEDs in display. Herein, LEDs based on CsPbI3 perovskite were used as basic units for fabricating eight-segment LED displays. The LEDs exhibited a luminance of 780 cd/m2 and an external quantum efficiency of 6%. The current-density and luminance vs driving voltage confirms the uniformity of these LEDs in the eight segments, which will promote the application of perovskite nanocrystalline LEDs in the field of full color display.
关键词： Perovskite,light-emitting diodes,eight-segment displays,quantum dots,display technology
更新于2025-09-12 10:27:22
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Modulation of Growth Kinetics of Vacuum-Deposited CsPbBr <sub/>3</sub> Films for Efficient Light-Emitting Diodes
摘要： Due to its excellent optical properties and good stability, all-inorganic halide perovskite CsPbX3 (X=I, Br, Cl) has been attracting interest for use in light-emitting diodes (LEDs). One challenge is improving the efficacy of the spatial confinement of excitons for higher luminescence efficiency. Here, we present a simple yet very effective strategy to form fine-grain-structured CsPbBr3 polycrystalline films prepared by thermal co-evaporation. The strategy involves controlling growth kinetics by adjusting the deposition flux which, along with growth temperature, determines the nucleation rate and therefore eventual grain structure. A correlation between deposition flux and average grain size was noted except for a very large deposition flux when there were large hillocks, which we attributed to the peculiar growth behavior of PbBr2 films. The growth conditions that produced a nano-scale grain structure and textured orientations without large hillocks also resulted in the highest luminescence efficiency as we anticipated. With the optimized CsPbBr3 light emitters, we demonstrate a green light-emitting (at 524 nm) LED with a maximum current efficiency of 1.07 cd/A and an extremely narrow electroluminescence spectrum of 18 nm, a result that highlights the potential of vacuum-processed CsPbBr3 films for high efficiency LEDs.
关键词： Light-emitting Diodes,Thermal co-evaporation,Perovskites,Vacuum deposition,LEDs,CsPbBr3
更新于2025-09-12 10:27:22
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Efficient All‐Solution‐Processed Perovskite Light‐Emitting Diodes Enabled by Small‐Molecule Doped Electron Injection Layers
摘要： Metal halide perovskites have attracted considerable attention in the field of light-emitting diodes due to their high color purity and solution processability. However, most perovskite light-emitting diodes (PeLEDs) employ thermally deposited charge transport layers (CTLs) on top of perovskite layers. In order to realize low-cost and scalable fabrication of PeLEDs, all-solution process is highly desired, but still remaining great challenges. Here, an efficient all-solution-processed green PeLEDs is reported by incorporating 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi) doped conjugated amino-alkyl substituted polyfluorene poly[(9,9-bis(3′-(N,N-dimethylamino) propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN) electron injection layer, achieving a maximum luminance of 9875 cd m?2, a high current efficiency of 10.41 cd A?1, and an external quantum efficiency of 3.19%. Since the solvents used for perovskite precursors and PFN are orthogonal, the protected and complete interface of perovskite film and CTL is effectively obtained by solution processes. The doping of TPBi into PFN not only enhances the capability of electron injection, but also significantly suppresses the emission quenching of perovskite films caused by the charge transfer between perovskite and PFN due to the reduced difference in their work functions. This work provides an efficient approach for the development of all-solution-processed PeLEDs.
关键词： light-emitting diodes,all-solution-processed PeLEDs,electron injection layers,charge transfer,perovskites
更新于2025-09-12 10:27:22
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Mussel‐Inspired Polymer Grafting on CsPbBr <sub/>3</sub> Perovskite Quantum Dots Enhancing the Environmental Stability
摘要： Mussel-inspired chemistry, motivated by the adhesive proteins secreted by mussels for attachment to wet surfaces, is an emerging technique for manipulating the surface properties of a variety of materials. Here, a facile mussel-inspired poly(N-vinyl pyrrolidone) (PVP) polymer encapsulation with trivial influence on inherent optical properties of perovskite quantum dots (QDs) is demonstrated to efficiently combat the low intrinsic thermal, chemical, and photostability of CsPbBr3 QDs. The suitability of photopolymer-processed PVP-CsPbBr3 QDs flexible films as color components in white light–emitting devices is substantiated.
关键词： perovskite quantum dots,stability,white light-emitting diodes,photoluminescence,polymer grafting
更新于2025-09-12 10:27:22
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Design of Blue Thermally Activated Delayed Fluorescent Emitter with Efficient Exciton Gathering Property for High-Performance Fully-Solution-Processed Hybrid White OLEDs
摘要： The blue TADF emitters are highly attractive in the fields of constructing hybrid white organic light-emitting diodes (WOLEDs) due to its high efficiency and color stability. However, few of blue TADF emitters can withstand sequential orthogonal solvents, making it impossible to fabricate the fully-solution-processed hybrid WOLEDs. Here, two TADF materials, PCz-4CzCN and TPA-4CzCN, were designed and synthesized by equipping the emissive core with nonconjugated bulky units, which can effectively enhance the solvent resistance ability without disturbing the TADF feature. The photophysical investigation indicates that phenylcarbazole unit can efficiently block the electromer formation to enhance the energy transfer and exciton utilization of the emitter. Accordingly, the blue OLEDs of PCz-4CzCN shows higher external quantum efficiency (EQE) of 22.6%, which is the best performance recorded among the fully-solution-processed blue OLEDs. Upon further doping the yellow phosphor PO-01, the fully-solution-processed TADF-phosphor (T-P) hybrid WOLEDs was successfully obtained with high performance for the first time. Thanks to the efficient exciplex formation, the turn on voltage of the white device are only 2.8 V, and the maximum brightness and power efficiency are as high as 53300 cd m-2 and 38.5 lm W-1, respectively, which are even higher than the previous reported T-P hybrid WOLEDs with a vacuum-deposited electron transfer layer.
关键词： fully solution-process,organic light emitting diodes,TADF,hybrid white,blue
更新于2025-09-12 10:27:22
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Investigation on Thermally Induced Efficiency Roll-Off: Toward Efficient and Ultrabright Quantum-Dot Light-Emitting Diodes
摘要： Quantum-dot light-emitting diodes (QLEDs) with high brightness have potential application in lighting and display. The high brightness is realized at high current density (J). However, at high J, the efficiency drops significantly, thereby limiting the achievable brightness. This notorious phenomenon has been known as efficiency roll-off, which is likely caused by the Auger- and/or thermal-induced emission quenching. In this work, we show that the Joule heat generated during device operation significantly affects the roll-off characteristics of QLEDs. To realize ultra-bright and efficient QLEDs, the thermal stability of QDs is improved by replacing the conventional oleic acid ligands with 1-dodecanethiol. By further using a substrate with high thermal conductivity, the Joule heat generated at high J is effectively dissipated. Because of the effective thermal management, thermal-induced emission quenching is significantly suppressed, and consequently, the QLEDs exhibit a high external quantum efficiency (EQE) of 16.6%, which is virtually droop-free over a wide range of brightness (e.g., EQE=16.1% @ 105 cd/m2 and 140 mA/cm2). Moreover, due to the reduced efficiency roll-off and enhanced heat dissipation, the demonstrated QLEDs can be operated at a very high J up to 3885 mA/cm2, thus enabling the devices to exhibit a record-high brightness of 1.6×106 cd/m2 and a lumen density of 500 lm/cm2. Our work demonstrates the significance of thermal management for the development of droop-free and ultra-bright QLED devices for a wide variety of applications including lighting, transparent display, projection display, outdoor digital signage, phototherapy and etc.
关键词： high brightness,light-emitting diodes,quantum dot,thermal energy,efficiency roll-off
更新于2025-09-12 10:27:22