High Solar Energy Utilization and Second-Order Nonlinear Optical Response of the Janus MoSTe/WSeTe vdW Heterostructure

Materials with an excellent controllable nonlinear optical response play significant roles in terahertz and optical imaging fields. The rich surface and interface properties of Janus transition metal dichalcogenides (TMDs) provide an ideal platform for studying the physical properties. Here, we report a Janus MoSTe/WSeTe vdW hetero structure with good mechanical stability, excellent electronic properties, and a linear/nonlinear optical response. Specifically, four possible interfaces are constructed, the mechanical strength gets doubled at the MoSTe monolayer, and the interfacial effect results in charge rearrangement and transformation of the band gap of the heterostructures from 0.36 to 1.33 eV; also, a stronger Rashba split occurs and the αR value reaches 0.65 eV/Å. Besides, the linear optical absorbance of the heterostructures is improved by about 10% over the component materials; the calculated absorbed photon flux Jabs values of heterostructures exceed 11.8 mA/cm2, which are much higher than those of GaAs and other materials. More importantly, different interfaces result in sensitivity to the polarization direction of the incident light and affect the second harmonic generation (SHG) signal intensity of the Janus MoSTe/WSeTe vdW heterostructure. Our results offer a systematic understanding of interface engineering to regulate the electronic structure and linear/nonlinear optical phenomena of heterostructures, providing a reference for the development of advanced optical materials and devices.