Type‐II AsP/As van der Waals Heterostructures: Tunable Anisotropic Electronic Structures and Optical Properties.

van der Waals (vdW) heterostructures, formed by stacking layered materials, have great potential for next‐generation nanoelectronics and optoelectronics with unique flexibility and high performance. Using density functional theory, it is demonstrated that all AA‐ and AB‐AsP/As heterostructures are semiconductors with intrinsic type‐II band alignments, facilitating the separation of photogenerated electron–hole pairs. The anisotropic electronic structures of the puckered AsP/As vdW heterostructures can be effectively modulated by applying tensile strains. The bandgaps exhibit nonmonotonic variations and monotonic changes with the strains exerted along x and y direction, respectively, both experiencing an indirect‐to‐direct bandgap transition. The external electric field gives rise to significant modulation on the bandgaps of the AsP/As vdW heterostructures. Specifically, the buckled AsP/As heterostructures can be changed from indirect to direct semiconductors with a small positive electric field from 0.3 to 0.6 V Å−1, which cannot be achieved under tensile strains. In addition, AsP/As vdW heterostructures exhibit excellent anisotropic light‐harvesting performances in visible light and ultraviolet regions and can be efficiently tuned by external strains, suggesting the potential applications in photovoltaics. The tunable anisotropic electronic and optical properties of the AsP/As vdW heterostructures may facilitate their practical applications for nanoelectronic devices and photovoltaics. [ABSTRACT FROM AUTHOR]