High efficiency pure-sulfide Cu(In,Ga)S2 solar cells with Cd-free buffer layer

A conversion efficiency of 15.5% on a pure-sulfide Cu(In,Ga)S2 solar cell with a Cd-free buffer layer was achieved. This is a big progress of pure-sulfide Cu(In,Ga)S2 cells whose conversion efficiency have not been improved since 2009. Our pure-sulfide Cu(In,Ga)S2 cells were fabricated by combing Cu-poor absorbers and Zn-based buffer layers. Current breakthrough to exceed the limit of 15% efficiency was brought by optimizing the Zn-based buffer layer. In this paper, we will review our recent progresses of our pure-sulfide Cu(In,Ga)S2 cells, especially in the impact of buffer layers for the pure-sulfide Cu(In,Ga)S2 cells. We keep exploring the potential of pure-sulfide Cu(In,Ga)S2 cells, and the latest results will be shown at the conference.