Comparison of chalcopyrite and kesterite thin-film solar cells

In this study, we investigate methods of improving the efficiency of Cu₂ZnSn(S,Se)₄ (CZTS)-based solar cells by comparing Cu(In,Ga)Se₂ (CIGSe)- and CZTS-based absorber layers. In particular, the CZTS-based absorber exhibits lower current characteristics than the CIGSe absorber layer in terms of the band gap alignment and electron-hole recombination at the CdS-absorber interface. Moreover, we demonstrate that defects are one of the causes of the voltage loss. In order to improve the efficiency of CZTS-based solar cells, it is important to control the band gap alignment at the CdS-absorber layer interface and to suppress the formation of secondary phases inside the absorber.