Defects in RbF - Treated Cu(InxGal-x)Se2 Solar Cells and Their Impact on Voc

Cu(In, Ga)Se
2
solar cell efficiency is limited by Voc due in large part to bulk defects limiting lifetime, but alkali treatments such as RbF recover some of the Voc loss. In this work, defects in RbF-treated and untreated CIGS were quantitatively characterized using DLTS and DLOS, and three main defects were identified in each sample. The RbF-PDT resulted in a large decrease in the mid-gap trap concentration, which was accompanied by a large improvement in minority carrier lifetime. This lifetime improvement combined with a change in doping accounted for a significant portion of the Voc improvement in the RbF CIGS.