Evolutionary structure prediction and electronic properties of indium oxide nanoclusters

Abstract

Indium sesquioxide is widely used as a transparent conducting oxide in modern optoelectronic devices; the rising cost of indium has generated interest in the nanoscale properties of In₂O₃, and questions arise as to the nature of its physicochemical properties below the bulk regime. We report the stable and metastable stoichiometric clusters of (In₂O₃)_n, where n = 1–10, as predicted from an evolutionary search within the classical interatomic potential and quantum density functional energy landscapes. In contrast to the paradigm set by ZnO, which favours high symmetry bubble-like structures, the In₂O₃ nanoclusters are found to tend towards dense, low symmetry structures approaching the bulk system at remarkably small molecular masses. Electronic characterisation is performed at the hybrid density functional and many-body GW levels to obtain accurate predictions of the spectroscopic properties, with mean values of the ionisation potentials and electron affinities calculated as 7.7 and 1.7 eV, respectively.