Effect of tensile strain on photoelectric properties of C-doped SnSe2 system

The geometric structure, stability, electronic structure and optical properties of the pristine SnSe₂ and C-doped SnSe₂ systems under tensile strain were computed using first principles. The findings indicate that the Sn-Se bond of the C-doped SnSe₂ system is longer than that of the pristine SnSe₂ system under the same tensile strain, and all systems in the low strain range can be stably formed. The electronic structure indicates that pristine SnSe₂ is an indirect bandgap semiconductor. Under the action of tensile strain, the introduction of C atoms leads to a transformation of the band gap type. The valence band of the C-doped SnSe₂ system is mainly attributed to the Se-4p and Sn-5p orbitals, while the conduction band is primarily assigned by Se-4p, Sn-5s and C-2p orbitals.The optical properties show that the peaks of ε₁(ω) and ε₂(ω) of both the pristine and doped systems are red-shifted under tensile strain, and the dielectric function ε₂(ω), absorption and reflection peaks of the doped system are lower than those of the pristine system, indicating that the introduction of C atoms can effectively improve the conductivity of the materials. Meanwhile, the absorption peak of the doped system was blue-shifted to the high-energy region relative to that of the pristine system. Under the action of tensile strain, the reflection peak of the pristine SnSe₂ system is redshifted, indicating that the tensile strain improves the utilization rate of the SnSe₂ system for ultraviolet light and can be used as an excellent alternative material for ultraviolet light detectors.