Computational discovery of In2XY2 (X, Y = S, Se, and Te; X ≠ Y) monolayers as multifunctional energy conversion materials

Abstract

Two-dimensional group III chalcogenides have gained global interest on account of their excellent prospects for applications in multifunctional energy conversion. Herein, via density functional theory calculations, we systematically unravel the electronic structures of In₂XY₂ (X, Y = S, Se, and Te; X ≠ Y) monolayers for their applications in energy conversion areas. Interestingly, the characteristics of the efficient spatial separation of photo-generated charge carriers, suitable band edge positions, and outstanding light-harvesting abilities indicate that In₂SSe₂, In₂STe₂, In₂SeS₂, and In₂SeTe₂ monolayers are desirable photocatalysts for the overall water splitting. It is found that In₂SSe₂ and In₂STe₂ act as donor materials, while In₂SeS₂ and In₂SeTe₂ act as acceptor materials in solar cells made of In₂SeS₂/In₂SSe₂ and In₂STe₂/In₂SeTe₂ heterostructures. It is highlighted that the theoretical power conversion efficiency reached 15.5% and 22.5% for In₂SeS₂/In₂SSe₂ and In₂STe₂/In₂SeTe₂ heterostructures, respectively. In particular, the ZT value of the In₂STe₂ monolayer reaches 3.2 at 500 K, indicating its potential as an up-and-coming candidate for next generation thermoelectric materials. The present research will pave the way for the practical applications of In₂XY₂ monolayers in the field of multifunctional energy conversion.