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 81(w) and 82(w) of both the pristine and doped systems are red-shifted under tensile strain, and the dielectric function 82(w), 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 highenergy 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.