Biaxial strain-modulated power conversion efficiency, electronic structures, and optical properties of type-II MoS2/BC6N vdW heterostructure: A density functional theory study

Abstract

The power conversion efficiency (PCE), electronic structures, and optical properties of a novel MoS2/BC6N van der Waals heterostructure (vdWH) were systematically investigated under different biaxial strains ranging from –8–8 % by first-principles density functional theory calculations. The semiconductive MoS2/BC6N vdWH exhibited indirect bandgap (1.02 eV) with type-II band alignment. The bandgap of the MoS2/BC6N vdWH decreased to 0.57 eV with increasing tensile strain, and increased to 1.57 eV with increasing compressive strain. When the strain exceeded –4 %, the band alignment of the vdWH transformed from type-II to type-I, exhibiting a direct bandgap. Strong optical absorption of the MoS2/BC6N vdWH was observed in the visible and ultraviolet regions. The maximum absorption peak produced a redshift with increasing tensile strain and a blueshift as increasing compressive strain. The PCE of the intrinsic MoS2/BC6N vdWH was 11.5 %, which gradually increased with increasing compressive strain but decreased with increasing tensile strain, that is, PCEs of 5.6 %, 8.0 %, 16.1 %, and 22.8 % for strain of 4 %, 2 %, –2 %, and –4 %, respectively. Therefore, the biaxial strain can effectively modulate the electronic structures, optical properties, and PCE of MoS2/BC6N vdWH. Moreover, their excellent optical properties and ultrahigh PCE indicate their significant potential for use in photovoltaic devices.