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.