Tailoring the band alignment and magnetic and optical properties of g-C3N4/WSe2 van der Waals heterostructures by vacancies and atomic doping

Tunable band structure and effective spatial separation of carriers are important for designing good optoelectronic devices. In this work, effects of interfacial defect including vacancies and [Formula: see text]- or [Formula: see text]-type doping on the band alignment and magnetic and optical properties of g-C 3 N 4 /WSe 2 van der Waals heterostructures are systematically investigated under the premise of spin-orbit coupling density-functional theory. The results illustrate that the pristine g-C 3 N 4 /WSe 2 heterostructure exhibits intrinsic type-I band alignment with a direct bandgap of 1.101 eV, and the absorption of UV-visible light can be effectively improved compared with that of isolated WSe 2 and g-C 3 N 4 monolayers. The N vacancies as well as [Formula: see text], [Formula: see text] and [Formula: see text] doping produce asymmetrical spin-up and spin-down states, bringing about the magnetization and even magnetic half-metallicity characteristics ([Formula: see text] and [Formula: see text] doping). The band edge positions of g-C 3 N 4 /WSe 2 heterostructure can be also well adjusted by introducing vacancies and [Formula: see text]- or [Formula: see text]-type doping in the g-C 3 N 4 layer, accompanied by the transition of band alignment from types I to II, which will remarkably promote the separation of photogenerated electron-hole pairs. The defective g-C 3 N 4 /WSe 2 heterostructures can be considered as a promising candidate for spintronics and optoelectronic devices.