Berlin 2024 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 4: Perovskite and photovoltaics I (joint session HL/KFM)

KFM 4.5: Vortrag

Montag, 18. März 2024, 10:30–10:45, EW 203

Nonlocal many-body dispersion for bulk properties: The particular case of cesium-based halide perovskites — Lin Yang¹, Ya Gao¹, Jingrui Li², •Guo-Xu Zhang¹, and Zhenbo Wang¹ — ¹Harbin Institute of Technology, Harbin, P. R. China — ²Xi’an Jiaotong University, Xi’an, P. R. China

Cesium-based all-inorganic halide perovskites have shown excellent photovoltaic properties. However, phase stability and transformations in different polymorphs remain rather poorly understood. Here, we investigate the cohesive, electronic properties and structural instabilities of CsPbI₃ and CsSnI₃ based on first-principles density-functional theory (DFT) calculations. Care has been taken to choose exchange-correlation functionals and zero-point vibrational effects have been included by performing phonon calculations. In particular, we compare different van der Waals (vdW) corrections to the DFT approaches. Our results demonstrate that nonlocal many-body dispersion interactions play a vital role in predicting the cohesive properties and phonon spectra of halide perovskites studies here. In addition, we find the anharmonicity cannot be neglected in order to correctly predict the phase stability and transitions of polymorphs. The quasiharmonic approximation method that partially include the anharmonicity is able to improve the predictions, in particular for CsSnI₃. We stress that both nonlocal many-body dispersion and full anharmonic terms should be considered for accurate studies of such type of materials.

Keywords: Halide perovskites; Density-functional theory; van der Waals interactions; Structural instabilities; Many-body dispersion