Excellent nonlinear optical effects in the MoS₂/CrOCl heterojunction

In recent years, the strong nonlinear optical (NLO) effects found in two-dimensional (2D) materials have attracted increasing research interest due to their promising applications in photonics and optoelectronics. Stacking 2D materials to form vdW heterojunctions is an efficient way to manipulate their physical properties. Recently, a MoS₂/CrOCl heterojunction with high carrier mobility, a high on/off ratio and high air stability was successfully obtained in experiments. Therefore, the NLO properties of this heterojunction are an interesting and urgent issue to be explored. Here, the NLO effects, including second harmonic generation (SHG) and bulk photovoltaic effect (BPVE), of the MoS₂/CrOCl heterojunction were investigated by first-principles calculations. The BPVE response in the heterojunction is very strong throughout the visible light region, and the shift photoconductivity reaches -1225.8 µA V^-2 when the incident light wavelength is 469.7 nm, which is dozens of times larger than that of traditional bulk BPVE materials, such as BaTiO₃ (30 µA V^-2) and PbTiO₃ (50 µA V^-2). Our results suggest that the MoS₂/CrOCl heterojunction has promising applications in optoelectronic devices, especially in photovoltaic devices.