Effects of non-metal doping and shear strain on the electronic, optical and magnetic properties of the PtS 2 /PtSe 2 van der Waals heterojunction

This paper investigates the effects of second-period atom doping (N, O, F, Ne) and shear strain on the optoelectronic properties and magnetism of the PtS 2 /PtSe 2 van der Waals heterojunction based on density functional theory. First, we identify the most stable heterostructure by examining the binding energy, and further validate it through phonon dispersion and dynamics. PtS 2 /PtSe 2 exhibits an indirect band gap of 0.49 eV and belongs to type-II band alignment. Doping N atoms into the PtSe 2 layer results in significant spin splitting, producing magnetism while maintaining semiconductor characteristics; however, doping into the PtS 2 layer leads to metallic properties, and the differential charge density map shows a substantial increase in charge transfer, providing theoretical guidance for the fabrication of high-performance chips. Similarly, doping N atoms into both layers results in metallic characteristics. The increase in shear strain in both directions uniformly reduces the band gap value but does not induce spin splitting. Additionally, the N-doped structure enhances absorption in the UV-A region, and doping in the PtSe 2 layer of the heterojunction also increases absorption in the UV-C region, improving by 6% compared to the intrinsic case. Applying 4% and 6% strain in the x-y direction can further enhance the absorption coefficient in this region, increasing it by nearly 11% compared to the intrinsic case. As the strain in the x-y direction increases, the absorption spectrum in the UV-A region experiences a redshift, increasing visible light absorption, which helps improve the efficiency of solar cells; conversely, an increase in strain in the y-x direction leads to a blue shift in the spectrum, enhancing UV light absorption. These findings may provide references for the development of high-performance optoelectronic devices.