Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 64: Focussed session: Theory and computation of electronic structure: new frontiers V (jointly with HL, DS)
O 64.1: Topical Talk
Donnerstag, 17. März 2011, 11:15–11:45, TRE Phy
Electronic excitations in thin-film materials for solar cells: beyond standard density functional theory — •Silvana Botti — LSI, École Polytechnique, CNRS, CEA-DSM, Palaiseau, France — LPMCN, Université Claude Bernard Lyon 1, CNRS, Villeurbanne, France — European Theoretical Spectroscopy Facility
Cu(In,Ga)(Se,S)2 (CIGS) thin-film solar cells have emerged as a technology that can challenge the current hegemony of silicon solar panels. CIGS conserve to a very high degree their electronic properties in a large non-stoichiometric range and are remarkably insensitive to radiation damage or impurities. Kesterites Cu2ZnSe(S,Se)4 have very similar electronic properties. Unlike CIGS, they are composed of abundant, non-toxic, less expensive chemical elements.
The origin of the exceptional electronic properties of these complex materials is still not completely understood, despite the large amount of experimental and theoretical work dedicated to that purpose. In particular, standard density functional theory (DFT) yields band structures in quantitative and qualitative disagreement with experiments. This is a serious problem when it comes to designing new materials for more efficient photovoltaic energy conversion.
I will discuss which theoretical approaches beyond standard DFT are reliable at a reasonable computational cost, together with the new physical insight that they allow to obtain.