High-efficiency Cu(In,Ga)Se2 thin-film solar cells with a CBD-ZnS buffer layer

High-efficiency cadmium-free Cu(In,Ga)Se-2 (CIGS) thin-film solar cells have been fabricated using a chemical bath deposition (CBD)-ZnS buffer layer, a wider band gap material than of conventional CBD-CdS. Energy dispersive X-ray microanalysis (EDX) revealed Zn interdiffusion in the CIGS thin film at the CBD-ZnS/CIGS solar cell interface, implying formation of a buried np junction at the surface of the CIGS film. The best cell to date yielded an active area efficiency of 17.2% after light soaking. This result suggests that CIGS solar cells with efficiencies as high as those fabricated using CdS buffer can be achieved even if Cd is not utilized. (C) 2001 Elsevier Science B.V. All rights reserved.