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HL: Fachverband Halbleiterphysik
HL 19: Focus Session: When theory meets experiment: Hybrid halide perovskites for applications beyond solar II (joint session HL/CPP)
HL 19.1: Hauptvortrag
Montag, 16. März 2020, 15:00–15:30, POT 251
Double perovskite electronic structures: A chemical perspective — •Adam Slavney1, Hemamala Karunadasa2, Linn Leppert3, and Bridget Connor2 — 1Department of Chemistry, Harvard University, Cambridge, Massachusetts, USA — 2Department of Chemistry, Stanford University, Stanford, California, USA — 3Institute of Physics, University of Bayreuth, Bayreuth, Germany
Halide double perovskites, of the formula A2BB'X6, are close analogs to the APbX3 lead halide perovskites and have attracted significant interest as possible non-toxic alternatives to the lead materials in perovskite photovoltaics. Double perovskites divide the formally +2 charge on the octahedral B site unevenly over two B sites, allowing for cations with charges from +1 - +4 to be incorporated into the perovskite lattice. I will discuss the results of our experimental and theoretical investigations into double perovskites over the last several years, with a particular emphasis on understanding the differences in electronic structure between single and double perovskites. The double perovskite electronic structure is largely dictated by the combination of the B and B* cations rather than either cation individually and I will provide simple rules which accurately predict the band structure from the chemical formula in nearly every case. Double perovskites electronic structures have features not available in single perovskites including symmetry-forbidden bandgaps and unusually small bandgaps generated by metal-metal charge transfer transitions. Finally, I will discuss some of the defect chemistry of double perovskites and how those lessons can be applied to halide perovskites more broadly.