Efficient and stable CIGS solar cells with ZnOS buffer layer

A chemical bath deposition (CBD) ZnOS process has been designed to yield repeatable and robust ZnOS/CIGS solar cells that do not require light soaking or annealing to reach conversion efficiency levels comparable with CdS/CIGS solar cells. In this study, copper content was varied over a wide range to understand its impact on these devices. Capacitance and temperature-dependent performance measurements were used to characterize the electrical performance as a function of Cu composition. The optimum Cu concentration was found to be about the same for both CBD CdS and CBD ZnOS junctions.