Influence of heat treatment and back contact processing on the performance of CdS/CdTe thin film solar cells produced in a CSS in-line system

Abstract CdS/CdTe photovoltaic cells were grown in a homemade close-spaced sublimation equipment where all steps of cell fabrication are carried out continuously, without breaking the vacuum. The best efficiency achieved was 7%. Some devices partially prepared in this system were finished (heat treatment and back contact processing) at the National Renewable Energy Laboratory and showed efficiencies in the range of 10–11%, due to higher values of fill factor and photocurrent. Comparison between the procedures followed in the two laboratories identified some critical issues in the CSS process carried out continuously, such as the temperature of the heat treatment and the nature of the back contact.