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

Sb 2 Se 3 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 (∼10 13 cm −3 ) and the low carrier collection efficiency due to the low carrier mobility (∼1.5 cm 2 V −1 s −1 ) hinder further efficiency improvement of Sb 2 Se 3 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 Sb 2 Se 3 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%. CuSCN suppresses the back surface recombination and induces grain boundary inversion through Cu diffusion to achieve 7.5% n-i-p Sb 2 Se 3 solar cells.