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

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 similar to 1 eV, whereas the larger band gap (LBG) material has a band gap of similar to 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.