Temperature Dependence of the Energy Levels of Methylammonium Lead Iodide Perovskite from First-Principles.
The journal of physical chemistry letters
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Saidi, W. A., Poncé, S., & Monserrat Sanchez, B. (2016). Temperature Dependence of the Energy Levels of Methylammonium Lead Iodide Perovskite from First-Principles.. The journal of physical chemistry letters, 7 (24), 5247-5252. https://doi.org/10.1021/acs.jpclett.6b02560
Environmental effects and intrinsic energy-loss processes lead to fluctuations in the operational temperature of solar cells, which can profoundly influence their power conversion efficiency. Here we determine from first-principles the effects of temperature on the band gap and band edges of the hybrid pervoskite CH3NH3PbI3 by accounting for electron-phonon coupling and thermal expansion. From 290 to 380 K, the computed band gap change of 40 meV coincides with the experimental change of 30-40 meV. The calculation of electron-phonon coupling in CH3NH3PbI3 is particularly intricate as the commonly used Allen-Heine-Cardona theory overestimates the band gap change with temperature, and excellent agreement with experiment is only obtained when including high-order terms in the electron-phonon interaction. We also find that spin-orbit coupling enhances the electron-phonon coupling strength but that the inclusion of nonlocal correlations using hybrid functionals has little effect. We reach similar conclusions in the metal-halide perovskite CsPbI3. Our results unambiguously confirm for the first time the importance of high-order terms in the electron-phonon coupling by direct comparison with experiment.
External DOI: https://doi.org/10.1021/acs.jpclett.6b02560
This record's URL: https://www.repository.cam.ac.uk/handle/1810/285508