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High‐Performance, Solution‐Processed, and Insulating‐Layer‐Free Light‐Emitting Diodes Based on Colloidal Quantum Dots
Author(s) -
Zhang Zhenxing,
Ye Yuxun,
Pu Chaodan,
Deng Yunzhou,
Dai Xingliang,
Chen Xiaopeng,
Chen Dong,
Zheng Xuerong,
Gao Yuan,
Fang Wei,
Peng Xiaogang,
Jin Yizheng
Publication year - 2018
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201801387
Subject(s) - materials science , quantum dot , fabrication , optoelectronics , diode , layer (electronics) , light emitting diode , exciton , electroluminescence , quantum efficiency , quenching (fluorescence) , nanocrystal , oxide , nanotechnology , optics , medicine , alternative medicine , physics , pathology , quantum mechanics , metallurgy , fluorescence
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 Zn 0.9 Mg 0.1 O 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.