Two-dimensional MoS2/GaN van der Waals heterostructures: tunable direct band alignments and excitonic optical properties for photovoltaic applications

Two-dimensional (2D) van der Waals heterostructures are ideal building blocks of optoelectronic devices for muti-functional applications. In this work, the electronic and optical properties of 2D MoS2/GaN van der Waals heterostructures (vdW HTs) are explored via first-principles calculations, considering interlayer coupling and external electric field modulations. The results show that 2D MoS2/GaN vdW HTs possess a direct gap about 1.79 eV with type-II band alignment and excellent optical absorbance about similar to 5.5 x 10(5) cm(-1). Moreover, changing interlayer coupling and applying external electric fields can effectively and broadly engineer its band gap and optical properties. These predicted results may be useful to experimentally construct ultra-thin optoelectronic devices based on 2D MoS2/GaN vdW HTs.