Optical Losses in Glass/ITO(ZnO)/CdS/Cu2ZnSn(SxSe1−x)4 Solar Cells with Different Kesterite Composition

In this work, optical losses in auxiliary layers of solar cells with the glass/n-ITO (ZnO)/n-CdS/p-Cu2ZnSn(SxSe1− x)4/rear contact structure (where x = 0; 0.30; 0.48; 0.67; 0.82; 1) was determined. The spectral dependences of the light transmittance to the absorbing layers of Cu2ZnSn (SxSe1−x)4 were calculated, taking into account the reflection of light from the boundaries of the contacting materials and its absorption in the auxiliary layers of the devices. Modeling the loss of optical energy processes was carried out for the thickness of the window layer dCdS equal to 25 nm, 50 nm, 75 nm, and 100 nm, and the thickness of the front transparent contact dITO(ZnO) = 100 nm and 200 nm. As a result, their maximum efficiencies were determined under illumination conditions of AM1.5G and AM1.5D solar cells, taking into account optical losses. Analysis of the modeling results made it possible to determine the composition of the Cu2ZnSn(SxSe1−x)4 solid solution, which is necessary to obtain the maximum efficiency of the solar cells under consideration and optimize the design of the solar cells.