@article{f465fd4b133243b9b0b213353a881787,
title = "Spectral Instability of Layered Mixed Halide Perovskites Results from Anion Phase Redistribution and Selective Hole Injection",
abstract = "Despite the ability to precisely tune their bandgap energies, mixed halide perovskites (MHPs) suffer from significant spectral instability, which obstructs their utilization for the rational design of light-emitting diodes. Here, we investigate the origin of the electroluminescence peak shifts in layered MHPs containing bromide and iodide. X-ray diffraction and steady-state absorption measurements prove effective integration of iodide into the cubic lattice and the spatially uniform distribution of halides in the ambient environment. However, the applied electric field during the device operation is found to drive the systematic halide migration. Quantum mechanical density functional theory calculations reveal that the different activation energies required for directional ion hopping lead to the redistribution of anions. In-depth analyses of the electroluminescence spectra indicate that the spectral shifting rate is dependent on the drift velocity of halides. Finally, it is suggested from our study that the dominant red emission is ascribed to the thermodynamically favorable selective hole injection. Our mechanistic study provides insights into the fundamental reason for the spectral instability of devices based on MHPs.",
keywords = "halide redistribution, ion migration, mixed halide perovskite, perovskite light-emitting diode, spectral instability",
author = "Yoonseo Nah and Omar Allam and Kim, {Han Seul} and Choi, {Ji Il} and Kim, {In Soo} and Jinwoo Byun and Kim, {Sang Ouk} and Jang, {Seung Soon} and Kim, {Dong Ha}",
note = "Funding Information: This work was supported by a National Research Foundation of Korea Grant funded by the Korean Government (NRF-2020R 1A 2C 3003958), the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korean government (MOTIE) (No. 20173010013340), and a Korea Basic Science Institute (National Research Facilities and Equipment Center) grant funded by the Ministry of Education (2020R 1A 6C 101B194). The simulation data have been generated with the active use of the NURION (KISTI-5) high-performance computing resources supported by the Korea Institute of Science and Technology Information (KISTI) (KSC-2019-CRE-0199 and TS-2020-RE-0020) and the Extreme Science and Engineering Discovery Environment{\textquoteright}s (XSEDE) Comet supercomputing cluster supported by the National Science Foundation (NSF). J.B. and S.O.K. were partially supported by the National Creative Research Initiative (CRI) Centre for Multi-Dimensional Directed Nanoscale Assembly (2015R 1A 3A 2033061) funded by the National Research Foundation (NRF) of Korea. Publisher Copyright: {\textcopyright} 2021 American Chemical Society. All rights reserved.",
year = "2021",
month = jan,
day = "26",
doi = "10.1021/acsnano.0c08897",
language = "English",
volume = "15",
pages = "1486--1496",
journal = "ACS Nano",
issn = "1936-0851",
publisher = "American Chemical Society",
number = "1",
}