Science Advances
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2024
·Vol. 10
·期 33
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IF 11.7
Xitong Zhu,Xiao Luo,Yunzhou Deng,Huan Wei,Feng Peng,Lei Ying,Fei Huang,Yuanyuan Hu,Yizheng Jin
Quantum-dot light-emitting diodes (QLEDs) are solution-processed electroluminescence devices with great potential as energy-saving, large-area, and low-cost display and lighting technologies. Ideally, the organic hole-transport layers (HTLs) in QLEDs should simultaneously deliver efficient hole injection and transport, effective electron blocking, and robust electrochemical stability. However, it is still challenging for a single HTL to fulfill all these stringent criteria. Here, we demonstrate a general design of doping-bilayer polymer-HTL architecture for stabilizing high-efficiency QLEDs. We show that the bilayer HTLs combining the electrochemical-stable polymer and the electron-blocking polymer unexpectedly increase the hole injection barrier. We mitigated the problem by p-doping of the underlying sublayer of the bilayer HTLs. Consequently, green QLEDs with an unprecedented maximum luminance of 1,340,000 cd m−2 and a record-long operational lifetime (T95 lifetime at an initial luminance of 1000 cd m−2 is 17,700 hours) were achieved. The universality of the strategy is examined in various polymer-HTL systems, providing a general route toward high-performance solution-processed QLEDs.
研究领域:
材料科学
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电气工程
·
光电子学
·
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PubMed
高影响因子
Journal of Physical Chemistry C
·
2021
·
IF 4.126
Zhiwei Yao,Chenghao Bi,Jianjun Tian
Quantum dot light-emitting diodes (QLEDs) show great potential in high-definition displays due to their narrow emission and high color purity. However, the imperfect quantum dots (QDs) with high trap density are difficult to be removed from QD solution, which could cause serious nonradiative recombination, thereby suppressing the improvement of QLEDs. Here, we devise a novel chemical filtering strategy with a bidentate coordination to remove the imperfect QDs. The bidentate ligand of ethanolamine (EA) with an amidogen and a carboxyl was directly added into the CdSe/CdS/ZnS core/shell/shell QD solution. Then, uncoordinated sites such as S2– and Zn2+ on the surface of QDs were bonded with the amidogen and carboxyl of EA, respectively, resulting in aggregations of the imperfect QDs with high defect density, which were precipitated from the solution. As a result, the photoluminescence quantum yield (PLQY) of the filtered QD solution increased to 93% because of the decrease in trap density. The size distribution of QDs was also improved after filtration. QLEDs fabricated with filtered QDs show a high external quantum efficiency (EQE) of 15.76% and luminance of 19,640 cd/m2, greater than those of the control devices. This strategy shows a great potential to be used in the large-scale treatment and production of QDs and QLEDs.
研究领域:
材料科学
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纳米技术
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光电子学
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高影响因子
Nano Research
·
2023
·Vol. 16
·期 7
·10215-10221
·
IF 9.9
Hu Qianqing,Si Junjie,Chen Desui,Hao Xiaoming,Xu Rui,Du Yihang,Du Zhuopeng,Gong Xinquan,Zhao Hong,Cai Peiqing,Ai Qi,Yao Xin,Yan Yu,Zhang Zenan,Cai Muzhi,Liu Wei,Kang Yongyin,Liu Zugang
All-solution-processed inverted quantum dot (QD) light-emitting diodes (QLEDs) with transparent bottom cathodes can be directly connected to the n-type thin-film transistors, offering a feasible solution for low-cost active matrix-driven QD displays. However, the subsequent solution-deposition of the hole-transporting layer destroys the underneath QD films, resulting in largely deteriorated device performance. Various strategies have been implemented to prevent QD film from dissolution, but all at a heavy cost of device performance suffering from either reduced efficiency or increased driving voltage. Here, a facile and effective water-treatment approach for QD film to fabricate inverted QLEDs through all solution processing is reported. The water treatment substitutes the long-chain oleate ligands with hydroxyl groups, resulting in significantly improved non-polar solvent resistance of the QD films. Importantly, the QD films reserve their excellent photoluminescence efficiency after water treatment. With the water-treated QD film as the emissive layer, all-solution-processed inverted red QLED with a peak external quantum efficiency of 19.6%, a turn-on voltage of 1.8 V, and a T 50 operational lifetime of 150,000 h at 100 cd·m −2 was achieved. Furthermore, efficient and low-voltage-driven green and blue QLEDs can also be prepared with this method. This work provides a feasible strategy for the fabrication of high-performance all-solution-processed inverted QLEDs, paving the way toward achieving QLEDs by all ink-jet printing.
研究领域:
材料科学
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光电技术
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纳米技术
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高影响因子
Applied Materials Today
·
2022
·
IF 8.663
Xikang Yang,Anlang Wu,Zhiqiang Deng,Zhihai Wu,Zhenfu Zhao,Ziyang Hu
Perovskite quantum dots (PeQDs) are emerging as one of the most promising candidates for next-generation display technology due to their outstanding optical and electrical properties. However, the inherent instability, lead-toxicity and poor electrical conductivity of PeQDs films have seriously hindered their commercial applications. To solve these problems, we adopted the strategy of Zr ions doping and in-situ passivation of CsPbBr 3 PeQDs with the short-chain inorganic ligand potassium thiocyanate (KSCN), which not only enhanced the stability and boosted the photoluminescence quantum yield (PLQY) of PeQDs films, but also improved their electrical conductivity. To further solve the problem of charge injection balance and improve the operating lifetime of the devices, we simultaneously used all-inorganic metal oxide semiconductor materials Mg-doped ZnO (Mg-ZnO) and Mg-doped NiO x (Mg-NiO x ) as the electron and hole transport layers of QLEDs (ETL and HTL), respectively. The operating stability of the devices was greatly improved while being able to withstand higher current densities. Therefore, using Zr-doped and KSCN passivated CsPbBr 3 (Zr doped CsPbBr 3 -KSCN) PeQDs as the light-emitting layer, we fabricated highly efficient and stable green-light all-inorganic quantum dots light-emitting diodes (QLEDs) with the maximum external quantum efficiency (EQE) of 13.8% and the maximum brightness of 24800 cd/m 2 . These green perovskite QLEDs provide a working half-life of 360 min (initial brightness is 1000 cd/m 2 ) and the operating half-life of the devices is more than two times higher than that of the reference devices. Our proposed strategy based on doping and in-situ inorganic ligand passivation will open a new avenue for fabricating efficient, stable and other colored perovskite QLEDs.
研究领域:
材料科学
·
电气工程
·
光电技术
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DOI
高影响因子
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