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Spectral Instability of Layered Mixed Halide Perovskites Results from Anion Phase Redistribution and Selective Hole Injection
- Title
- Spectral Instability of Layered Mixed Halide Perovskites Results from Anion Phase Redistribution and Selective Hole Injection
- Authors
- Nah, Yoonseo; Allam, Omar; Kim, Han Seul; Choi, Ji Il; Kim, In Soo; Byun, Jinwoo; Kim, Sang Ouk; Jang, Seung Soon; Kim, Dong Ha
- Ewha Authors
- 김동하
- SCOPUS Author ID
- 김동하
- Issue Date
- 2021
- Journal Title
- ACS NANO
- ISSN
- 1936-0851
1936-086X
- Citation
- ACS NANO vol. 15, no. 1, pp. 1486 - 1496
- Keywords
- mixed halide perovskite; perovskite light-emitting diode; ion migration; halide redistribution; spectral instability
- Publisher
- AMER CHEMICAL SOC
- Indexed
- SCIE; SCOPUS
- Document Type
- Article
- 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.
- DOI
- 10.1021/acsnano.0c08897
- Appears in Collections:
- 자연과학대학 > 화학·나노과학전공 > Journal papers
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