Tuning the optoelectronic properties of PtS2/PtSe2 heterostructure via strain engineering

In this paper, based on the first-principles calculation method of density functional theory, the PtS₂/PtSe₂ heterostructure with the lowest formation energy is selected from five different stacking modes. At the same time, the phonon spectrum of PtS₂/PtSe₂ heterostructure has no imaginary frequency, so the structure is stable. After that, the changes of photoelectric properties of heterostructures under tensile and compressive strains were studied. It is concluded that the PtS₂/PtSe₂ heterostructure is a semiconductor with indirect band gap and type II band arrangement. With the increase of tensile strain, the band gap value decreases from 0.927 to 0.565 eV, and the minimum value of the conduction band is transferred from the high symmetry point M point to the K point by 8% biaxial tensile strain. The biaxial tensile strain can effectively improve the dielectric constant of the PtS₂/PtSe₂ heterostructure. When the strain reaches 8%, the dielectric constant is nearly twice as high as the intrinsic value and reaches 11.6, which improves the charge retention ability. The light absorption of PtS₂/PtSe₂ heterostructure reaches 13.7 × 10⁴ cm⁻¹ under compressive strain, and the stability of light absorption is enhanced. The optical reflection ability of PtS₂/PtSe₂ heterostructure is significantly enhanced under tensile strain, indicating that the biaxial strain has a regulatory effect on the absorption and reflection ability of light. The valley values of all systems near the ultraviolet region show a linear increase trend, which changes the transmittance of the heterostructure. These findings broaden the application of PtS₂/PtSe₂ heterostructures in optoelectronic engineering.