Iodine Vacancies do not Cause Nonradiative Recombination in Halide Perovskites
2023
Jingda Zhang | Xie Zhang | Mark E. Turiansky | Chris G. Van de Walle
The iodine vacancy (V_{I}) has frequently been discussed as a strong nonradiative recombination center in halide perovskites. This proposition was mainly based on the presence of charge-state transition levels in the band gap, as found in early first-principles calculations. In this work, we perform accurate hybrid-density-functional calculations for V_{I} in CsPbI_{3}, CsSnI_{3}, and CsGeI_{3} and find that V_{I} does not have any transition levels in the band gap in CsPbI_{3}, in contrast to the results from calculations based on semilocal functionals. The iodine vacancy V_{I} does introduce levels in the band gap in CsSnI_{3} and CsGeI_{3}, but our explicitly computed nonradiative capture coefficients demonstrate that V_{I} has a negligible impact on nonradiative recombination. Our study corrects a misunderstanding of the role of V_{I} in the iodide-based perovskites, and shifts the focus toward identifying and mitigating actual recombination centers in order to further improve the optoelectronic performance.
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