Perspective—Multinary Oxide Semiconductors for Solar Fuels Generation: Closing the Performance Gap between Theory and Practice

We address the current state-of-the-art in the development of multinary oxides—a family of compounds that has long interested Prof. John B. Goodenough. Specifically, we focus on their use as photoelectrodes for solar fuels generation. Using optical data and assuming an idealized 100% incident photon-to-electron conversion efficiency, it is possible to project the maximum short-circuit photocurrent efficiency to be expected for a given oxide semiconductor. The performance gap between this theoretical value and that realized experimentally is shown to be sizable for all but a couple candidates. The technical issues underlying this gap and strategies for closing it are presented.