Based on first-principles calculations, we demonstrated that a GeSe/SnSe heterostructure has a type-II band alignment and a direct band gap. The predicted photoelectric conversion efficiency (PCE) for the GeSe/SnSe heterostructure reaches 21.47%.
Based on the first-principles calculations, we demonstrated that a GeSe/SnSe heterostructure has type-II band alignment and a direct band gap, which can effectively prevent the recombination of photogenerated electron–hole pairs. Moreover, the GeSe/SnSe heterostructure also exhibits strong optical absorption intensity, which can reach the order of 10 5 cm −1. Our predicted photoelectric conversion efficiency (PCE) for the GeSe/SnSe heterostructure reaches 21.47%. We also found that the hole carrier mobility of the GeSe/SnSe heterostructure along the x direction has been significantly improved to 6.42 × 10 4 cm 2 V −1 s −1, which is higher than that of black phosphorus (1 × 10 4 cm 2 V −1 s −1). By applying a vertical external electric field, we found that the band gap and band offset of the GeSe/SnSe heterojunction can be effectively tuned. The revealed type-II band alignment, strong optical absorption, superior PCE and superior hole carrier mobility of the GeSe/SnSe heterostructure imply that this new proposed material has broad application prospects in solar cells.