Regensburg 2019 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 53: Perovskite and Hybrid Photovolatics I (joint session HL/CPP)

CPP 53.6: Vortrag

Donnerstag, 4. April 2019, 10:45–11:00, H36

Density-functional-theory modeling of point defects in halide-perovskite alloys — •Li Jingrui and Patrick Rinke — Department of Applied Physics, Aalto University, Finland

Perovskite solar cells (PSCs) are a promising emergent technology, because their photo-conversion-efficiency has been increasing rapidly in recent years. In these cells, the photoabsorbing material is a hybrid (organic-inorganic) halide perovskites (ABX₃), that is usually grown with low-temperature solution-based synthesis. This synthesis method introduces many point defects, that may critically affect the electronic and structural properties of the PSCs. To gain microscopic insight, we used density-functional-theory to study a series of point defects of halide-perovskite alloys with ion-mixing at A (methylammonium, Cs and Rb), B (Pb and Sn) and X (I, Br and Cl) sites. The considered defects include A- and X-site vacancies and native interstitials in different charge states, as well as K and H impurities. For each model system, a 4×4×4 perovskite supercell was relaxed using the PBEsol exchange-correlation functional. Then the electronic structure and defect formation energy were calculated using the hybrid HSE06 functional. Our results indicate that the defect formation energy sensitively depends on the phase and composition of halide perovskites. For halogen vacancies, the +1 state that has very small impact on the electronic structure is the most stable in a large Fermi-energy range. Only within the strongly n-type doped region, neutral or negatively-charged halogen vacancies will be formed, which introduce states in the band gap and significantly limit the PSC efficiency.