PN/PAs-WSe2 van der Waals heterostructures for solar cell and photodetector
Xinyi Zheng, Yadong Wei, Kaijuan Pang, Ngeywo Tolbert Kaner, Dalin Kong, Xiaodong Xu, Jianqun Yang, Xingji Li, Weiqi Li
Abstract
Abstract By first-principles calculations, we investigate the geometric stability, electronic and optical properties of the type-II PN-WSe 2 and type-I PAs-WSe 2 van der Waals heterostructures(vdWH). They are p -type semiconductors with indirect band gaps of 1.09 eV and 1.08 eV based on PBE functional respectively. By applying the external gate field, the PAs-WSe 2 heterostructure would transform to the type-II band alignment from the type-I. With the increasing of magnitude of the electric field, two heterostructures turn into the n -type semiconductors and eventually into metal. Especially, PN/PAs-WSe 2 vdWH are both high refractive index materials at low frequencies and show negative refractive index at high frequencies. Because of the steady absorption in ultraviolet region, the PAs-WSe 2 heterostructure is a highly sensitive UV detector material with wide spectrum. The type-II PN-WSe 2 heterostructure possesses giant and broadband absorption in the near-infrared and visible regions, and its solar power conversion efficiency of 13.8% is higher than the reported GaTe–InSe (9.1%), MoS 2 / p -Si (5.23%) and organic solar cells (11.7%). It does project PN-WSe 2 heterostructure a potential for application in excitons-based solar cells.