Photochemical deposition of ZnS buffer layers for Cu(In, Ga)Se2 thin film solar cells via reusable solutions

A new bath composition for ZnS buffer layer deposition is presented allowing its photochemical growth on CIGSe absorbers. The main advantages of this solution compared to classical CBD-Zn(S, O) bath are: the deposition occurs at room temperature, the concentration of chemical precursors is 10 times lower than classical CBD-Zn(S, O), the use of a complexing agent such as ammonia is avoided and the same bath can be reused for several depositions. The same bath can be re-used for at least 4 times, leading to efficiencies between 13 and 14%, which is similar to what is obtained with CdS-buffered references.