Nah, Yoonseo Allam, Omar Kim, Han Seul Choi, Ji Il Kim, In Soo Byun, Jinwoo Kim, Sang Ouk Jang, Seung Soon Kim, Dong Ha 2024-01-19T15:32:45Z 2024-01-19T15:32:45Z 2021-10-21 2021-01-26 1936-0851 https://pubs.kist.re.kr/handle/201004/117504 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. English AMER CHEMICAL SOC TOTAL-ENERGY CALCULATIONS ELASTIC BAND METHOD OPTICAL-PROPERTIES ION MIGRATION SOLAR-CELLS EFFICIENT MANAGEMENT POINTS IODIDE Spectral Instability of Layered Mixed Halide Perovskites Results from Anion Phase Redistribution and Selective Hole Injection Article 10.1021/acsnano.0c08897 1 ACS NANO, v.15, no.1, pp.1486 - 1496 ACS NANO 15 1 1486 1496 scie scopus 000613942700120 2-s2.0-85100152859 Chemistry, Multidisciplinary Chemistry, Physical Nanoscience & Nanotechnology Materials Science, Multidisciplinary Chemistry Science & Technology - Other Topics Materials Science Article TOTAL-ENERGY CALCULATIONS ELASTIC BAND METHOD OPTICAL-PROPERTIES ION MIGRATION SOLAR-CELLS EFFICIENT MANAGEMENT POINTS IODIDE mixed halide perovskite perovskite light-emitting diode ion migration halide redistribution spectral instability