Significantly enhancing back contact adhesion and improving stability of Cu2(Zn,Cd)Sn(S,Se)4 solar cell by a rational carbon doping strategy

Abstract The back contact adhesion is the important factor of the microstructural performance which can determine the optoelectronic properties of the kesterite-based solar cells. Here, we present a rational and effective strategy to significantly enhance the back contact adhesion of Cu 2 (Zn,Cd)Sn(S,Se) 4 (CZCTSSe) absorber layers by insetting the appropriate thickness carbon-doping CZCTS thin films. We chose the oleylamine as the carbon-doping reagent which can generate a small amount of carbon in the annealing process. The suitable thickness carbon-doping CZCTS films can significantly change the crystal growth mechanism of CZCTSSe absorber layers, and eliminate the holes in the back contact. The efficiency of CZCTSSe solar cells fabricated by insetting the appropriate thickness carbon-doping CZCTS films is above 7%, and shows the excellent repeatability and long-term air stability compared with the control devices.