First-Principles Materials Design of High-Performing Bulk Photovoltaics with the LiNbO3 Structure

Here, the bulk photovoltaic effect is a long-known but poorly understood phenomenon. Recently, however, the multiferroic bismuth ferrite has been observed to produce strong photovoltaic response to visible light, suggesting that the effect has been underexploited as well. Here we present three polar oxides in the LiNbO₃ structure that we predict to have band gaps in the 1-2 eV range and very high bulk photovoltaic response: PbNiO₃, Mg_1/2Zn_1/2PbO₃, and LiBiO₃. All three have band gaps determined by cations with d¹⁰s⁰ electronic configurations, leading to conduction bands composed of cation s-orbitals and O p-orbitals. This both dramatically lowers the band gap and increases the bulk photovoltaic response by as much as an order of magnitude over previous materials, demonstrating the potential for high-performing bulk photovoltaics.