Type-II MoSi<sub>2</sub>N<sub>4</sub>/MoS<sub>2</sub> van der Waals Heterostructure with Excellent Optoelectronic Performance and Tunable Electronic Properties
Xuhui Xu, Lei Yang, Quan Gao, Xinxin Jiang, Dongmei Li, Bin Cui, Desheng Liu
Abstract
van der Waals heterostructures (vdWHs) provide a new strategy to broaden the application of two-dimensional (2D) materials in novel nanodevices. Based on first-principles calculations, we propose a 2D MoSi 2 N 4 /MoS 2 vdWH for light harvesting and photovoltaic applications. The MoSi 2 N 4 /MoS 2 vdWH exhibits a semiconducting characteristic with an indirect band gap of 1.12 eV. The type-II band alignment of MoSi 2 N 4 /MoS 2 vdWH facilitates the spatial separation of photogenerated electron–hole pairs. Therefore, the MoSi 2 N 4 /MoS 2 vdWH exhibits excellent optical absorption (∼10 5 cm –1 ) and large photocurrent density (1.6 mA cm –2 ) in the visible range. Furthermore, performing external electric field and biaxial strain can effectively regulate the band gap and band alignment of MoSi 2 N 4 /MoS 2 vdWH. Notably, the tensile strain significantly enhances the optical absorption and total photocurrent of MoSi 2 N 4 /MoS 2 vdWH. These findings reveal the potential of MoSi 2 N 4 /MoS 2 vdWH as a new alternative for optoelectronic devices and provide new possibilities for designing strain-tunable photovoltaic devices.