A type-II GeSe/SnTe heterostructure with superior optical absorption and strain tunable photovoltaic properties

We constructed the GeSe/SnTe van der Waals (vdW) two-dimensional (2D) heterostructure with the use of the first-principles calculation, which has a 0.481 eV indirect bandgap and the type-II band alignment. The GeSe/SnTe heterostructure has superior wide range light absorption with the maximum value of 8.69 105 cm-1, and the heterostructure also exhibits anisotropic carrier mobilities with the maximum value of 8.36 103 cm2 V-1 s-1. By strain engineering, the band structure of GeSe/SnTe heterostructure is able to be modulated effectively. Moreover, by applying biaxial strain, we can greatly enhance the photoelectric conversion efficiency (PCE) of GeSe/SnTe heterostructure, which can reach 15.29% under 4% tensile strain. Our calculation results reveal that the GeSe/SnTe heterostructure can be considered to apply in the nextgeneration solar cells.