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HL: Fachverband Halbleiterphysik

HL 1: Focus Session: When theory meets experiment: Hybrid halide perovskites for applications beyond solar

HL 1.2: Hauptvortrag

Montag, 27. September 2021, 10:30–11:00, H4

Anharmonic semiconductors - Lessons Learned from Halide perovskites — •Omer Yaffe — Weizmann Institute of Science, Rehovot, Israel

In semiconductor physics, the dielectric response, charge carrier mobility and other electronic material properties at finite temperatures, are always treated within the framework of the harmonic approximation. This approach is very successful in capturing the properties of tetrahedrally bonded semiconductors such as silicon and GaAs.

In my talk, I will show that halide perovskites are fundamentally different due to their strongly anharmonic lattice dynamics. Large amplitude, local polar fluctuations induced by lattice anharmonicity localize the electronic states and enhance the screening of electric charge within the material. In other words, in some aspects, halide perovskites behave more like a liquid than a crystalline solid. I will also discuss the implications of these findings on other families of semiconductors such as organic and rock-salt semiconductors.