Impacts of Post-Treatments on Cell Performance of CIGS Solar Cells With Zn-Compound Buffer Layers

The postdeposition treatments, such as ammonia rinsing, light soaking, and heat light soaking on cell performances of Cu(In,Ga)Se₂ (CIGS) solar cells with Zn-compound buffer layers, are investigated. The impacts of these treatments are discussed in connection with the band alignment at the transparent conducting oxide (TCO)/buffer/CIGS interface. Three types of CIGS solar cells with sputter-deposited ZnO:Al/CBD-ZnS(O,OH), MOCVD-ZnO:B/CBD-ZnS(O,OH), and MOCVD-ZnO:B/ALD-Zn(O,S) are investigated in this paper. The importance of the combination of buffer/TCO materials and deposition processes is discussed. We demonstrate that the adjustment of an S/(S+O) atomic ratio relevant to the band alignment at the buffer/CIGS interface is critical to achieve high-efficiency CIGS solar cells with Zn-compound buffer layer.