Promising quaternary chalcogenides as high-band-gap semiconductors for tandem photoelectrochemical water splitting devices: A computational screening approach

Abstract

Significantly high efficiency of the photoelectrochemical (PEC) water splitting process can be achieved by using two semiconductors in a tandem device. The smaller band gap (SBG) material in the device has a band gap of $\ensuremath{\sim}1$ eV, whereas the larger band gap (LBG) material has a band gap of $\ensuremath{\sim}2$ eV. However, a very limited number of LBG semiconductors have been explored and here we investigate systematically the quaternary chalcogenides of ${A}_{2}{BCX}_{4}$ type. We calculate the properties of the materials in six different crystal structures. Based on the criteria of thermodynamic stability, band gap, and good charge transport properties, we find a handful of potential LBG candidates from a pool of 1368 materials. Additionally, by extrapolating our analyses we also find a few SBG semiconductors, some of which are already known, e.g., CZTS/AgZTSe. This consolidates our approach for the LBG semiconductors and therefore invites experimental investigation of the candidates identified as efficient LBG semiconductors for the tandem devices.