Regensburg 2025 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 1: Perovskite and Photovoltaics I (joint session HL/KFM)
HL 1.8: Talk
Monday, March 17, 2025, 11:30–11:45, H13
Polymorphism at surface in CsPbI3 from first principles — •Jasurbek Gulomov1, Guido Roma1, Jacky Even2, and Marios Zacharias2 — 1Université Paris-Saclay, CEA, Service de recherche en Corrosion et Comportement des Matériaux, SRMP, Gif sur Yvette, 91191, France — 2Université Rennes, INSA Rennes, CNRS, Institut FOTON - UMR 6082, F-35000 Rennes, France
Halide perovskites show great potential for optoelectronics and photovoltaics, but challenges with ion migration and phase stability remain.Atomic-scale phenomena at surfaces and interfaces must be understood to block ion migration and enhance passivation. A peculiar property of these materials is the tendency to gain energy by disordered structural distortions, dubbed polymorphism, in contrast to the view of a perfectly symmetric monomorphous structure. Using first-principles calculations, we investigate the electronic and structural properties of polymorphous bulk CsPbI3 and its 100 surface with two terminations. For the bulk, we generate a dynamically stable polymorphous structure for the cubic high-temperature phase using the method recently proposed by M. Zacharias et al. [1]. The energy gain and band gap opening are essentially linked to the increased average length of Pb-I bonds. Then we extend the concept of polymorphism to the surface, analyzing surface dipoles and work functions by comparing monomorphous and polymorphous slabs with experimental data. Our results tend to confirm the occurrence of polymorphism at surfaces in CsPbI3.
[1] Zacharias, M., et al., npj Comput. Mater. 9, 153 (2023).
Keywords: Polymorphism; Halide perovskite; Surface; DFT