Boosting Solar Cell Performance via Centrally Localized Ag in Solution-Processed Cu(In,Ga)(S,Se)₂Thin Film Solar Cells

Fabrication of Cu(In,Ga)(S,Se)2 (CIGSSe) absorber films from environmentally friendly solutions under ambient air conditions for use in solar cells has shown promise for the low-cost mass production of CIGSSe solar cells. However, the limited power conversion efficiency (PCE) of these solar cells compared with their vacuum-processed counterparts has been a critical setback to their practical applications. This study aims to fabricate solution-processed CIGSSe solar cells with high PCEs by incorporation of Ag into the precursor layer of the CIGSSe absorber films. The results showed that Ag doping promoted grain growth by accelerating Se uptake, irrespective of the location within the CIGSSe film. Nevertheless, uniform Ag doping formed crevices that lowered the PCE of the cells, while centrally localizing the doped Ag prevented the formation of crevices, resulting in high PCEs up to 15.3%. Our results demonstrate that carefully doping Ag into a selected area of the precursor layer of the CIGSSe films can realize solution-processed chalcopyrite solar cells with high PCE.