7.5% n-i-p Sb2Se3 solar cells with CuSCN as a hole-transport layer

Sb2Se3 is a promising non-toxic, Earth-abundant, stable thin-film solar cell absorber material. However, the low built-in potential caused by the low intrinsic doping density (approximate to 10(13) cm(-3)) and the low carrier collection efficiency due to the low carrier mobility (approximate to 1.5 cm(2) V-1 s(-1)) hinder further efficiency improvement of Sb2Se3 solar cells. Therefore, an effective hole-transport layer (HTL) is necessary to further boost the built-in potential and assist carrier collection. Herein we attempt to improve the efficiency of Sb2Se3 solar cells by using CuSCN as an HTL. CuSCN as an HTL suppresses the back surface recombination, and enhances the built-in potential and carrier collection efficiency. Meanwhile, materials and physical properties characterization reveals that CuSCN provides Cu ions which induce grain boundary inversion, and therefore separate photo-generated carriers more efficiently. Consequently, we obtained a device efficiency of 7.50%.