High voltage Cu2ZnSnS4 submodules by hybrid buffer layer

Efficiency of 9.2% on Cu₂ZnSnS₄ submodule was achieved by applying hybrid buffer layer with combination of In-based buffer and Cd-based buffer layers. The hybrid buffer especially enhanced open circuit voltage. Finally world highest voltage of 758mV was achieved by this technique. The XPS depth profile showed there was remarkable diffusion of Cu and O as well as Cd and In. The UPS depth profile indicated that the hybrid buffer layer could improve carrier recombination at the interfaces not only between the buffer and the absorber layers but also between the i-ZnO and the buffer layers.