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Extraordinary Mass Transport and Self‐Assembly: A Pathway to Fabricate Luminescent CsPbBr 3 and Light‐Emitting Diodes by Vapor‐Phase Deposition
Author(s) -
Dumont Antoine,
Ho Kevin,
Kung HaoTing,
Qiu Chenyue,
Li Peicheng,
Luo Deying,
Zhao Yongbiao,
Walker Gilbert,
Lu ZhengHong
Publication year - 2020
Publication title -
advanced materials interfaces
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.671
H-Index - 65
ISSN - 2196-7350
DOI - 10.1002/admi.202000506
Subject(s) - materials science , perovskite (structure) , electroluminescence , photoluminescence , optoelectronics , light emitting diode , luminescence , overlayer , passivation , diode , scanning electron microscope , chemical vapor deposition , thin film , analytical chemistry (journal) , nanotechnology , chemical engineering , layer (electronics) , composite material , chemistry , chromatography , engineering
Halide perovskites have been shown to be promising materials in making light‐emitting diodes. At present, almost all of perovskite materials are made by solution‐based synthesis. There are very limited reports on fabricating perovskite LEDs by vapor‐phase deposition (VPD), a method that can be easily scaled up for commercial production. In this paper, dual‐source VPD is used to fabricate stable CsPbBr 3 perovskite thin films with excellent luminescent properties. Scanning electron microscope and atomic force microscope studies show that CsPbBr 3 films, when coated with a thin LiBr overlayer, demonstrate an extraordinary mass transport at room temperature to re‐assemble into well‐defined islands. LiBr is also shown to passivate nonradiative defects and boost photoluminescence performance of the CsPbBr 3 , improving the intensity by a factor of 11 for a nominal 18 nm perovskite film and leading to extremely narrow photoluminescence peaks (16 nm FWHM). This self‐assembled perovskite LED shows major improvement in the electroluminescence performance, almost tripling the brightness of reference devices. X‐ray photoelectron spectroscopy measurement shows that surface LiBr improves Cs/Pb chemical stoichiometry, reduces Br vacancies, and shift the Fermi energy level toward conduction band minimum.