Transparent conducting oxides of relevance to organic electronics: Electronic structures of their interfaces with organic layers

Transparent conducting oxides (TCO) are a critical component of many organic electronic devices including organic solar cells and light-emitting diodes. In this Perspective, we discuss what we have learned from our theoretical investigations, at the density functional theory (DFT) level, of the electronic structures of several technologically relevant transparent conducting oxides and their interfaces with organic layers. In particular, we describe how DFT calculations can be used to provide a detailed understanding of (i) the impact of surface modification by an organic monolayer on the interfacial electronic structure and the work function; (ii) the electronic characteristics of TCO surfaces as a function of surface hydroxylation and the presence of various intrinsic and extrinsic defects; and (iii) the nature of the charge transfer taking place between an organic semiconducting layer and a TCO electrode when considering the physisorption of a monolayer of π-conjugated organic molecules on the TCO surfaces.