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Novel strategy to improve the efficiency roll-off at high luminance and operational lifetime of hybrid white OLEDs via employing an assistant layer with triplet-triplet annihilation up-conversion characteristics
摘要： The efficiency roll-off at high luminance and operational lifetime remain a major challenge before the wide applications of white organic light-emitting diodes (WOLEDs) technology. Here we present a novel strategy to improve the efficiency roll-off at high luminance and operational lifetime by employing an assistant layer with triplet-triplet annihilation (TTA) up-conversion characteristics in emitters. It can be seen that at high luminance, the partial triplet energies in emitters will transfer to the TTA assistant layer and finally lead to the TTA emission, which reduces the exciton quenching at high luminance. Therefore, not only the efficiency roll-off, but also the operational lifetime are greatly improved. The resulting hybrid WOLEDs exhibited the maximum forward-viewing external quantum efficiency and power efficiency of 23.6% and 68.8 lm W?1, and they only dropped to 18.3% and 38.1 lm W?1 at 1000 cd m?2 and 17.1% and 25.9 lm W?1 at 5000 cd m?2, which are significantly higher than 10.5% and 17.9 lm W?1 at 5000 cd m?2 of WOLEDs without TTA assistant layer. Furthermore, the operational half-lifetime of the resulting hybrid WOLEDs also reached 600 hours at the luminance of 1000 cd m?2, which is nearly two-fold longer than that of the reference WOLEDs.
关键词： exciton diffusion,triplet-triplet annihilation up-conversion,Efficiency roll-off,white organic light-emitting diodes,lifetime
更新于2025-09-23 15:21:01
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High-performance white organic light-emitting diodes with doping-free device architecture based on the exciton adjusting interfacial exciplex
摘要： White organic light-emitting diodes (WOLEDs) with doping-free device architecture have aroused more attention due to their attractive merits such as simplified fabrication procedures and reduced costs. However, the electroluminescence performance of that is still manifestly unsatisfactory and needs to be further improved. Here, high-performance doping-free two-color and three-color WOLEDs with the accurate manipulation of excitons have been successfully fabricated by optimizing the interfacial exciplex. As a result, two-color WOLEDs exhibit the controllable electroluminescence spectra with a wide correlated color temperature (CCT) spanning from 2878 to 9895 K at the voltage of 4 V, as well as the maximum forward-viewing power and current efficiencies of 83.2 lm W?1 and 63.3 cd A?1, respectively. The three-color WOLED not only realizes the maximum efficiencies of 50.1 lm W?1 and 44.7 cd A?1, but also exhibits superior color stability with a color rendering index of 86, a CCT of 2679 K, and a Commission International de I’Eclairage coordinates of (0.49, 0.46) at the voltage of 5 V. Such surprising efficiencies obtained in our WOLEDs indicate that the reasonable application of interfacial exciplex should be a helpful way to develop high-performance and low cost WOLEDs with a simple technology.
关键词： high-performance,color stability,White organic light-emitting diodes,doping-free,interfacial exciplex
更新于2025-09-23 15:19:57
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Converting an organic light-emitting diode from blue to white with Bragg modes
摘要： Organic light-emitting diodes (OLEDs) have been established as versatile light sources that allow for easy integration in large area surfaces and flexible substrates. In addition, the low fabrication cost of OLEDs renders them particularly attractive as general lighting sources. Current methods for the fabrication of white-light OLEDs rely on the combination of multiple organic emitters and/or the incorporation of multiple cavity modes in a thick active medium. These architectures introduce formidable challenges in both device design and performance improvements, namely the decrease of efficiency with increasing brightness (efficiency roll-off) and short operational lifetime. Here we demonstrate, for the first time, white light generation in an OLED consisting of a sub-100 nm-thick blue single emissive layer coupled to the photonic Bragg modes of a dielectric distributed Bragg reflector (DBR). We show that the Bragg modes, although primarily located inside the DBR stack, can significantly overlap with the emissive layer, thus efficiently enhancing emission and outcoupling of photons at selected wavelengths across the entire visible light spectrum. Moreover, we show that color temperature can be tuned by the DBR parameters, offering great versatility in the optimization of white-light emission spectra.
关键词： distributed Bragg reflector,white organic light-emitting diodes (WOLEDs),Fabry-Pérot modes,electroluminescence color conversion,organic semiconductors
更新于2025-09-19 17:13:59
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High-performance hybrid white organic light-emitting diodes with bipolar host material and thermally activated delayed fluorescent emitter
摘要： Bipolar host material and thermally activated delayed fluorescent (TADF) emitter were used in hybrid white organic light-emitting diodes (OLEDs) with the aim to achieve high performance. First of all, the single color OLEDs was optimized by changing the thickness of hole transporting layer, electron transporting layer and the doping concentration of emission material. Then, white organic light-emitting diodes (WOLEDs) were fabricated on the basis of the former single color OLEDs by modifying the doping concentration of TADF emitter. Finally, an optimized white device shows the best results of 43.67 cd/A, 45.73 lm/W and 18.52% for current efficiency, power efficiency and external quantum efficiency, respectively. This research may supply a theoretical basis for the development of WOLEDs.
关键词： Thermally activated delayed fluorescent (TADF),Energy transfer,Hybrid white organic light-emitting diodes (WOLEDs),Bipolar host material,High performance
更新于2025-09-16 10:30:52
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A new strategy for structuring white organic light-emitting diodes by combining complementary emissions in the same interface
摘要： In this work, we proposed a new strategy for structuring white organic light-emitting diodes (WOLEDs) using all exciplex emissions, where the white devices can be fabricated by simply depositing several exciplex acceptor layers on the same exciplex donor layer in a vertical direction, and complementary exciplex emissions can be realized in the same exciplex donor layer interface for forming white emission. Based on this new strategy, a series of WOLEDs with different array arrangements of different exciplex acceptor layers on the same exciplex donor layer were demonstrated. The device with a bisected blue-yellow exciplex acceptor layer on the same exciplex donor layer realizes good two-color white emission with a high color rendering index of 71, and also achieves a high current efficiency of 3.17 cd A?1. Moreover, the emission spectra and device performance of white devices can be adjusted and improved by simply changing the array arrangements of different exciplex acceptor layers on the same exciplex donor layer. More importantly, the proposed new strategy can effectively solve the interface problem induced by employing interface exciplexes to realize multi-color white emission, which provides a new approach to accomplish all exciplex emission WOLEDs.
关键词： exciplex emissions,device performance,color rendering index,white organic light-emitting diodes,current efficiency
更新于2025-09-16 10:30:52
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Modulation of F?rster and Dexter Interactions in Single‐Emissive‐Layer All‐Fluorescent WOLEDs for Improved Efficiency and Extended Lifetime
摘要： White organic light-emitting diodes (WOLEDs) with thermally activated delayed fluorophor sensitized fluorescence (TSF) have aroused wide attention, considering their potential for full exciton utilization without noble-metal containing phosphors. However, performances of TSF-WOLEDs with a single-emissive-layer (SEL) still suffer from low exciton utilization and insufficient blue emission for proper white balance. Here, by modulating F?rster and Dexter interactions in SEL-TSF-WOLEDs, high efficiencies, balanced white spectra, and extended lifetimes are realized simultaneously. Given the different dependencies of F?rster and Dexter interactions on intermolecular distances, sterically shielded blue thermally activated delayed fluorescence (TADF) emitters and orange conventional fluorescent dopants (CFDs) with electronically inert peripheral units are adopted to enlarge distances of electronically active chromophores, not only blocking the Dexter interaction to prevent exciton loss but also finely suppressing the F?rster one to guarantee balanced white emission with sufficient blue components. It thus provides the possibility to maximize device performances in a large range of CFD concentrations. A record high maximum external quantum efficiency/power efficiency of 19.6%/52.2 lm W?1, Commission Internationale de L’Eclairage coordinate of (0.33, 0.45), and prolonged half-lifetime of over 2300 h at an initial luminance of 1000 cd m?2 are realized simultaneously for SEL-TSF-WOLEDs, paving the way toward practical applications.
关键词： sensitizing process,thermally activated delayed fluorescence,exciton interactions,white organic light-emitting diodes,sterically inert substituents
更新于2025-09-12 10:27:22
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High efficiency, high color rendering index white organic light-emitting diodes based on thermally activated delayed fluorescence materials
摘要： High ef?ciency white organic light-emitting diodes (WOLEDs) with simple device architecture are desirable for next-generation light sources. However, it is still challenging in the construction of high-performance WOLEDs with a simple device structure. Based on a thermally activated delayed ?uorescence (TADF) blue emitter 2SPAc-MPM and a TADF yellow emitter TXO-TPA, high performance two-color WOLEDs with simple device architecture are demonstrated. Bene?ting from ef?cient energy transfer and wide coverage over the visible spectrum, optimized WOLED devices that have a single emitting layer (s-EML) provide a maximum color rendering index (CRI) and maximum external quantum ef?ciency (EQE) of 78.1 and 21.8%, respectively. More importantly, with multiple emitting layers (m-EMLs), a maximum EQE of 14.5% and a high CRI of 90.7 can be achieved. These results are among the best for the two-color WOLEDs with two TADF emitters.
关键词： white organic light-emitting diodes,high efficiency,thermally activated delayed fluorescence,high color rendering index
更新于2025-09-12 10:27:22
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Management of Exciton for Highly-Efficient Hybrid White Organic Light-Emitting Diodes with a Non-Doped Blue Emissive Layer
摘要： Hybrid white organic light-emitting diodes (WOLEDs) have drawn great attention both for display and solid-state lighting purposes because of the combined advantages of desirable stability of ?uorescent dyes and high e?ciency of phosphorescent materials. However, in most WOLEDs, obtaining high e?ciency often requires complex device structures. Herein, we achieved high-e?ciency hybrid WOLEDs using a simple but e?cacious structure, which included a non-doped blue emissive layer (EML) to separate the exciton recombination zone from the light emission region. After optimization of the device structure, the WOLEDs showed a maximum power e?ciency (PE), current e?ciency (CE), and external quantum e?ciency (EQE) of 82.3 lm/W, 70.0 cd/A, and 22.2%, respectively. Our results presented here provided a new option for promoting simple-structure hybrid WOLEDs with superior performance.
关键词： hybrid,exciton management,non-doped blue emissive layer,white organic light-emitting diodes
更新于2025-09-12 10:27:22
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Blue-emitting dendritic molecule with dual functionality as host and dopant for solution-processed white OLEDs with red-emitting material
摘要： In this study, a three-armed dendritic molecule, 1,3,5-tris(10-(4-(2,6-diphenylpyrimidin-4-yl)phenyl)-9,9-diphenyl-9,10-dihydroacridin-2-yl)benzene (3PDPAc), was successfully synthesized and utilized as a blue dopant and its host of two-component white organic light-emitting diodes (WOLEDs). The high molecular weight of dendritic 3PDPAc showed an advantage in the production of rigid thin films with fine surface morphology after doping with red-emitting 7-(7,7-dimethyl-5,13,13-triphenyl-7,13-dihydro-5H-indeno[1,2-b]acridin-2-yl)benzo[c][1,2,5]thiadiazole-4-carbonitrile (IABTCN). Transient photoluminescence spectroscopy confirmed that 3PDPAc and IABTCN displayed conventional fluorescence behavior. Furthermore, it was possible to form a two-component emission layer with 3PDPAc and IABTCN when fabricating a WOLED. The WOLED device bearing 3PDPAc and IABTCN (99.5:0.5 wt. ratio) exhibited 3.80% of the maximum external quantum efficiency (EQE) and CIE coordinates of (0.33, 0.34) which indicates almost pure white emission. The chromaticity of white color emission could be tuned from cool white to warm white by varying the concentration of IABTCN. Moreover, the device with 3PDPAc and IABTCN has been observed to display emission stability because of the miscibility of the host and dopants. Thus, the dendritic structure of 3PDPAc is advantageous for fabrication of a rigid emitting layer.
关键词： White organic light-emitting diodes,Blend film,Solution-process,Dendritic molecule
更新于2025-09-11 14:15:04