Physico-chemical Analysis of the Properties and Stability of CdS and CdS:O to Be Applied in Thin-Film Solar Cells

Oxygenated cadmium sulfide (CdS:O) has emerged as a promising photovoltaic material, improving the CdTe solar cell spectra response and due to its potential, it could be applied in different kinds of thin-film solar cells. However, despite CdS:O benefits, its stability and its interface with CdTe have not been widely studied. This work study the physico-chemical properties of CdS and CdS:O films are studied, in addition a window layer is proposed consisting of CdS/CdS:O (bi-layer). Analyzing these samples in three stages: 1) as-deposited, 2) annealed, and 3) after CdTe deposit in order to determine its stability.The results showed that high temperature and reactive atmosphere generates a structural rearrangement and secondary phase formation in the window layer. Chemical composition was analyzed by XPS deep profile, suggesting a homogenous element distribution into film. The implementation of the bilayer in CdTe/bi-layer/glass structure helped to control the oxygen interdiffusion towards to absorber layer; this improves the stability at the cell junction, thereby increasing the electrical properties in the solar cell.