Dresden 2017 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 19: Fundamentals of Perovskite Photovoltaics III (jointly with CPP/HL)
DS 19.8: Vortrag
Dienstag, 21. März 2017, 11:45–12:00, ZEU 222
Band Edge Engineering of Hybrid Halide Perovskites for Solar Cell Applications - Insights from Density Functional Theory — •Linn Leppert1,2, Sebastian E. Reyes-Lillo1,2, and Jeffrey B. Neaton1,2,3 — 1Molecular Foundry, Lawrence Berkeley National Laboratory — 2Department of Physics, University of California Berkeley — 3Kavli Energy NanoScience Institute at Berkeley
Efficiencies of solar cells based on hybrid halide perovskite absorbers have reached 22%, making them serious contenders to silicon solar cells. Nevertheless, the toxicity of lead, the material's instability, as well as pressing questions about the role of structural heterogeneities present challenges to its large scale fabrication and long term use. Recently it has been shown that photovoltaic properties vary significantly between different crystal facets of perovskite thin films, suggesting an appreciable effect of electric fields on the local electronic structure [1]. In this contribution, I will elucidate the coupling between electric polarization, which increases as a function of the macroscopic alignment of the organic moieties, and the band edge electronic structure. In particular the Rashba effect, an energy band splitting in k-space, increases with increasing polarization, indicating significant tunability with experimentally feasible applied fields. The effect can be tuned further by chemical substitution of the organic molecule as well as by anisotropic strain, allowing for considerable Rashba splitting even in the absence of electric fields [2]. [1] S. Leblebinci, L. Leppert, et al., Nature Energy 1, 16093 (2016). [2] L. Leppert et al., J. Phys. Chem. Lett. 7, 3683 (2016).