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Synthesis of Cu‐Modified Nickel Oxide Nanocrystals and Their Applications as Hole‐Injection layers for Quantum‐Dot Light‐Emitting Diodes
Author(s) -
Du Hui,
Ma Luying,
Wang Xin,
Li Yifei,
Xu Maopeng,
Liang Xiaoyong,
Chen Desui,
Jin Yizheng
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202101744
Subject(s) - non blocking i/o , materials science , nanocrystal , quantum dot , nickel oxide , annealing (glass) , oxide , light emitting diode , diode , optoelectronics , nanotechnology , thin film , chemical engineering , metallurgy , chemistry , catalysis , organic chemistry , engineering
Solution‐processed NiO x thin films have been applied as hole‐injection layers (HILs) in quantum‐dot light‐emitting diodes (QLEDs). The commonly used NiO x HILs are prepared by the precursor‐based route, which requires high annealing temperatures of over 275 °C to in situ convert the precursors into oxide films. Such high processing temperatures of NiO x HILs hinder their applications in flexible devices. Herein, we report a low‐temperature approach based on Cu‐modified NiO x (NiO x ‐Cu) nanocrystals to prepare HILs. A simple post‐synthetic surface‐modification step, which anchors the copper agents onto the surfaces of oxide nanocrystals, is developed to improve the electrical conductivity of the low‐temperature‐processed (135 °C) oxide‐nanocrystal thin films. In consequence, QLEDs based on the NiO x ‐Cu HILs exhibit an external quantum efficiency of 17.5 % and a T 95 operational lifetime of ∼2,800 h at an initial brightness of 1,000 cd m −2 , meeting the commercialization requirements for display applications. The results shed light on the potential of using NiO x ‐Cu HILs for realizing high‐performance flexible QLEDs.