Optical and Piezoelectric Properties of Strained Orthorhombic PdS₂

We investigate optical and piezoelectric properties of the orthorhombic PdS ₂ under symmetrical biaxial tensile strains with various magnitudes. The ab initio simulation results found that the peaks of the refractive index, extinction coefficient, absorption coefficient, and reflectivity of the orthorhombic PdS ₂ red-shift with the tensile strains. Specifically, we discover that the absorption coefficient of the strained orthorhombic PdS ₂ (4.01 × 10 ⁵ /cm -5.52 × 10 ⁵ /cm) is much higher than traditional optoelectronics, piezoelectric, and piezophototronic materials such as Si, Ge, GaInAs, ZnO, and monolayer MoS ₂ demonstrating much wider absorption spectrum (670-1033 nm). Moreover, the piezoelectric constant of the orthorhombic PdS ₂ is calculated from 0% to 8% tensile strains. Simulation results show the orthorhombic PdS ₂ with 4% tensile strain has a strong piezoelectric effect (1.33 C/m ² ), which is 100-5000 times higher than other deformation magnitudes. The results indicate that the orthorhombic PdS ₂ will have potential application in piezophotonic and piezoelectric devices.