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

Abstract

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 (∼10¹³ cm⁻³) and the low carrier collection efficiency due to the low carrier mobility (∼1.5 cm² 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%.