Interfaces of high-efficiency kesterite Cu 2 ZnSnS(e) 4 thin film solar cells

Cu 2 ZnSnS(e) 4 (CZTS(e)) solar cells have attracted much attention due to the elemental abundance and the non-toxicity. However, the record efficiency of 12.6% for Cu 2 ZnSn(S,Se) 4 (CZTSSe) solar cells is much lower than that of Cu(In,Ga)Se 2 (CIGS) solar cells. One crucial reason is the recombination at interfaces. In recent years, large amount investigations have been done to analyze the interfacial problems and improve the interfacial properties via a variety of methods. This paper gives a review of progresses on interfaces of CZTS(e) solar cells, including: (i) the band alignment optimization at buffer/CZTS(e) interface, (ii) tailoring the thickness of MoS(e) 2 interfacial layers between CZTS(e) absorber and Mo back contact, (iii) the passivation of rear interface, (iv) the passivation of front interface, and (v) the etching of secondary phases.