Oxide Heterostructures for Efficient Solar Cells

We propose an unexplored class of absorbing materials for high-efficiency solar cells: heterostructures of transition-metal oxides. In particular, LaVO₃ grown on SrTiO₃ has a direct band gap ∼1.1eV in the optimal range as well as an internal potential gradient, which can greatly help to separate the photogenerated electron-hole pairs. Furthermore, oxide heterostructures afford the flexibility to combine LaVO₃ with other materials such as LaFeO₃ in order to achieve even higher efficiencies with band-gap graded solar cells. We use density-functional theory to demonstrate these features.