High‐Performance,Solution‐Processed,and Insulating‐Layer‐Free Light‐Emitting Diodes Based on Colloidal Quantum Dots |
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| Authors: | Zhenxing Zhang Yuxun Ye Chaodan Pu Yunzhou Deng Xingliang Dai Xiaopeng Chen Dong Chen Xuerong Zheng Yuan Gao Wei Fang Xiaogang Peng Yizheng Jin |
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| Affiliation: | 1. Centre for Chemistry of High‐Performance & Novel Materials, State Key Laboratory of Silicon Materials, Department of Chemistry, Zhejiang University, Hangzhou, China;2. State Key Laboratory of Silicon Materials, Centre for Chemistry of High‐Performance & Novel Materials, School of Materials Science and Engineering, Hangzhou, China;3. Centre for Chemistry of High‐Performance & Novel Materials, Department of Chemistry, Hangzhou, China;4. Najing Technology Corporation LTD., Hangzhou, China;5. Center for Chemistry of High‐Performance & Novel Materials, State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, China |
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| Abstract: | Quantum‐dot light‐emitting diodes (QLEDs) may combine superior properties of colloidal quantum dots (QDs) and advantages of solution‐based fabrication techniques to realize high‐performance, large‐area, and low‐cost electroluminescence devices. In the state‐of‐the‐art red QLED, an ultrathin insulating layer inserted between the QD layer and the oxide electron‐transporting layer (ETL) is crucial for both optimizing charge balance and preserving the QDs' emissive properties. However, this key insulating layer demands very accurate and precise control over thicknesses at sub‐10 nm level, causing substantial difficulties for industrial production. Here, it is reported that interfacial exciton quenching and charge balance can be independently controlled and optimized, leading to devices with efficiency and lifetime comparable to those of state‐of‐the‐art devices. Suppressing exciton quenching at the ETL–QD interface, which is identified as being obligatory for high‐performance devices, is achieved by adopting Zn0.9Mg0.1O nanocrystals, instead of ZnO nanocrystals, as ETLs. Optimizing charge balance is readily addressed by other device engineering approaches, such as controlling the oxide ETL/cathode interface and adjusting the thickness of the oxide ETL. These findings are extended to fabrication of high‐efficiency green QLEDs without ultrathin insulating layers. The work may rationalize the design and fabrication of high‐performance QLEDs without ultrathin insulating layers, representing a step forward to large‐scale production and commercialization. |
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| Keywords: | charge balance efficiency exciton quenching light‐emitting diodes quantum dots |
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