Theoretical design of BAs/WX2 (X = S, Se) heterostructures for high-performance photovoltaic applications from DFT calculations

In this paper, based on first principle calculations, we systematically investigate thermal, mechanical, electronic and optical properties of hetemstructures composed of boron arsenide (BAs) and WX2 (X = S, Se). The binding energy (289.7 meV and 484.6 meV for BAs/WS2 and BAs/WSe2, respectively), phonon spectra, molecular dynamics and elastic deformation resistance indicate that the heterostructures are structurally, dynamically, and mechanically stable. The investigated van der Waals (vdWs) heterostructures (BAs/WS2 and BAs/WSe2) are all direct bandgap (0.6 eV and 0.7 eV, respectively) semiconductors, where the BAs/WS2 vdWs heterostructure possesses a type-II band alignment, which promotes the separation of photogenerated carriers and prolong their lifetime significantly. The BAs/WSe2 vdWs heterostructure exhibits a type-I band alignment, which in turn facilitates the rapid recombination of photogenerated carriers. Both BAs/WS2 and BAs/WSe2 heterostructures possess high carrier mobility (10(2) similar to 10(3) cm(2)/Vs) and optical absorptivity (-10(5) cm(-1)) in a wide range from ultraviolet to visible light region, making them highly efficient for solar energy. The band structures and carrier mobilities of BAs/WX2 hetemstructures are significantly affected by the spin-orbit coupling (SOC) effect. In addition, the external electric field can tailor the band structures including the transition between the direct and the indirect band gaps and the evolution between the type-I and type-II band alignments. The theoretical predictions suggest that BAs/WX2 heterostructures are promising candidates for future nanoelectmnics and optoelectronic devices, providing some valuable information for future experimental research.