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Low Roll‐Off Perovskite Quantum Dot Light‐Emitting Diodes Achieved by Augmenting Hole Mobility
Author(s) -
Wang Yu,
Teng Yu,
Lu Po,
Shen Xinyu,
Jia Pei,
Lu Min,
Shi Zhifeng,
Dong Bin,
Yu William W.,
Zhang Yu
Publication year - 2020
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201910140
Subject(s) - light emitting diode , optoelectronics , diode , materials science , quantum dot , quantum efficiency , perovskite (structure) , radiative transfer , current density , spontaneous emission , photon , electron , electron mobility , physics , optics , chemistry , quantum mechanics , crystallography , laser
The external quantum efficiencies (EQEs) of perovskite quantum dot light‐emitting diodes (QD‐LEDs) are close to the out‐coupling efficiency limitation. However, these high‐performance QD‐LEDs still suffer from a serious issue of efficiency roll‐off at high current density. More injected carriers produce photons less efficiently, strongly suggesting the variation of ratio between radiative and non‐radiative recombination. An approach is proposed to balance the carrier distribution and achieve high EQE at high current density. The average interdot distance between QDs is reduced and this facilitates carrier transport in QD films and thus electrons and holes have a balanced distribution in QD layers. Such encouraging results augment the proportion of radiative recombination, make devices with peak EQE of 12.7%, and present a great device performance at high current density with an EQE roll‐off of 11% at 500 mA cm −2 (the lowest roll‐off known so far) where the EQE is still over 11%.