Critical issues for high-efficiency low-cost CIGS solar cells and modules

High-efficiency CIGS solar cells and submodules have been developed at AIST. By developing the water-vapor assisted deposition technique, widegap CIGS solar cells with conversion efficiencies of over 18% with V_oc=0.744V have been demonstrated. The conversion efficiencies of integrated submodules on 10×10cm² sodalime glass substrates have been improved up to η=16.2% by using coevaporation process. These results indicate that the CIGS technologies are competitive with the current Si and CdTe technologies in terms of both cost and performance.