First-principles calculations of structural, electronic and optical properties of CdTexS1-x and Cd1-xZnxS ternary alloys

Abstract

Structural, electronic and optical properties of Cd1-xZnxS and CdTexS1-x alloys at different Te and Zn concentrations (x = 0, x = 0.25, x = 0.5, x = 0.75 and x = 1) are investigated using the density functional theory (DFT). The structural parameters of these ternary alloys are optimized using the functional PBEsol, as a version of GGA. Electronic and optical properties are calculated using the TB-mBJ functional. Our results show that the variation of the cell parameters for the two alloys are in good agreement with parabolic Vegard's law and the gap energy is reduced by increasing the Te concentration for the CdTexS1-x alloy but for Cd1-xZnxS, the gap energy shifted to blue range by increasing the Zn concentration. The band structure of the both alloys at different concentrations shows a direct band gap. The optical properties observed, in the visible range, an enhancement of the absorption coefficient for CdTexS1-x with Te concentration and an improvement of the transmittance windows for Cd1-xZnxS by increasing the Zn content. Our investigation confirm the use of these materials in the optoelectronic applications and shows that CdTexS1-x can be candidate as absorber material in the solar cells and Cd1-xZnxS as transparent optical window for the same application.