Cu 2 ZnSnS 4 (CZTS) has attracted much attention recently as an absorber layer material in a heterojunction solar cell. Using the first-principles method, we calculate the band offsets for the CdS/CZTS heterojunction. The valence band offset ΔE v is 1.2 eV for the (001) CdS/CZTS heterointerface and 1.0 eV for the (010) heterointerface, when CZTS is considered to crystallize in the kesterite structure. When CZTS is considered to crystallize in the stannite structure, ΔE v = 1.1 eV for the (001)

more »

... eterointerface and ΔE v = 1.3 eV for the (010) heterointerface. In any case, the conduction band minimum of CZTS is higher than that of CdS, and the conduction band offset ΔE c is in a range between 0.1 and 0.4 eV.