Origin of electronic and optical trends in ternary In2O3(ZnO)n transparent conducting oxides (n=1,3,5): Hybrid density functional theory calculations

Ternary oxides formed from zinc and indium have demonstrated potential for commercial optoelectronic applications. We present state-of-the-art hybrid density functional theory calculations for Zn-poor and Zn-rich compositions of the crystalline In2O3(ZnO)(n) compounds. We reveal the origin of the redshift in optical transitions compared to the two component oxides: symmetry forbidden band-edge transitions in In2O3 are overcome on formation of the superlattices, with Zn-O contributions to the top of the valence band. Increasing n results in the localization of the conduction-band minimum on the In-O networks. This enhanced localization explains why Zn-poor compounds (lower n) exhibit optimal conductivity.