Electronic and Optical Properties of the BAs/SnS2 Van Der Waals Heterostructure under Strain and Electric Field and Its Potential Application in Solar Cells

Layered van der Waals heterostructures composed of two or more distinct two-dimensional materials exhibit remarkable physical properties, offering great potential for the design of novel architectures in high-performance optoelectronic devices. In this work, we systematically investigate the geometric configuration and optoelectronic properties of the heterojunction formed by a monolayer of Boron Arsenide (BAs) and a monolayer of Tin Disulfide (SnS2) using first-principles calculations based on density functional theory (DFT). The results demonstrate that the vertically stacked BAs/SnS2 heterostructure is structurally stable in its ground state, with a band gap of 0.88 eV and a type-II band alignment. Notably, both biaxial strain and an external electric field can significantly modulate the band gap and band structure of the system. Under biaxial compressive strain ranging from-10 % to-4 %, the band gap increases monotonically. However, when the strain is further relaxed to the range of-4 % to 10 %, the band gap begins to decrease. In the case of an applied electric field varying from-0.5 to 0.5 V/& Aring;, the band gap initially increases linearly with the field strength, and the rate of increase slows down as the electric field approaches 0.3 V/& Aring;. Both biaxial strain and electric field are capable of inducing a transition between type-II and type-I band alignments. Moreover, the BAs/SnS2 heterostructure exhibits a theoretical photovoltaic conversion efficiency of approximately 26 % under normal conditions. With appropriate strain and electric field modulation, this efficiency can be enhanced to as high as 34 %. These findings highlight the promising potential of the BAs/SnS2 heterostructure for applications in photovoltaics and optoelectronics.