Structural, electronic and optical properties of Cd_1-xZn_xS and CdTe_xS_1-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 CdTe_xS_1-x alloy but for Cd_1-xZn_xS, 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 CdTe_xS_1-x with Te concentration and an improvement of the transmittance windows for Cd_1-xZn_xS by increasing the Zn content. Our investigation confirm the use of these materials in the optoelectronic applications and shows that CdTe_xS_1-x can be candidate as absorber material in the solar cells and Cd_1-xZn_xS as transparent optical window for the same application.

Cd _1-x Zn _x S和CdTe _x S _1-x合金在不同的Te和Zn浓度下的结构，电子和光学性质（x  = 0，x  = 0.25，x  = 0.5，x  = 0.75和x = 1）使用密度泛函理论（DFT）进行研究。这些三元合金的结构参数使用功能性PBEsol（作为GGA的一种）进行了优化。使用TB-mBJ函数计算电子和光学性质。我们的结果表明，两种合金的晶胞参数变化与抛物线Vegard定律非常吻合，并且通过增加CdTe _x S _1-x合金（但Cd _1-x Zn _x）的Te浓度来降低间隙能。S，通过增加锌的浓度，能隙能量转移到蓝色范围。两种合金在不同浓度下的能带结构均显示出直接的带隙。在可见光范围内观察到的光学性质是，通过增加Zn含量，CdTe _x S _1-x的吸收系数随Te浓度的增加而提高，而Cd _1-x Zn _x S的透射率窗的改善。我们的研究证实了这些材料在光电应用中的用途，并表明CdTe _x S _1-x可以用作太阳能电池中的吸收材料，而Cd _1-x Zn _x S可以用作同一应用的透明光学窗口。