Strain-tunable electronic and optical properties of a Janus PtSSe-SnSSe van der Waals heterostructure

Janus van der Waals (vdW) heterostructures are of great interest due to their intrinsic asymmetry, built-in electric fields, and tunable physical properties, making them attractive for advanced nanoelectronic and optoelectronic applications. In this article, the effect of strain on Janus PtSSeSnSSe van der Waals (vdW) heterostructure is studied using first-principles density functional theory (DFT) calculations. The electronic band structure and optical absorption characteristics were first analysed in the unstrained configuration. Subsequently, biaxial strain was applied to examine its influence on the band structure, charge density distribution, local electrostatic potential, charge transfer, and carrier effective masses. Our findings reveal that the band gap decreases under tensile strain, slightly increases under mild compressive strain, and reduces again under strong compression. Strain also significantly modifies the optical response, enhancing the absorption intensity, particularly in the visible region. Additionally, the redistribution of charge and changes in the electrostatic potential under strain provide key insights into interlayer coupling and built-in electric fields in Janus systems. The PtSSe–SnSSe heterostructure exhibits highly tunable electronic and optical properties under strain, highlighting its strong potential for next-generation strain-engineered nanoelectronic and optoelectronic devices.