Efficient planar Sb₂S₃ solar cells using a low-temperature solution-processed tin oxide electron conductor

Efficient planar antimony sulfide (Sb₂S₃) heterojunction solar cells have been made using chemical bath deposited (CBD) Sb₂S₃ as the absorber, low-temperature solution-processed tin oxide (SnO₂) as the electron conductor and poly (3-hexylthiophene) (P3HT) as the hole conductor. A solar conversion efficiency of 2.8% was obtained at 1 sun illumination using a planar device consisting of F-doped SnO₂ substrate/SnO₂/CBD-Sb₂S₃/P3HT/Au, whereas the solar cells based on a titanium dioxide (TiO₂) electron conductor exhibited a power conversion efficiency of 1.9%. Compared with conventional Sb₂S₃ sensitized solar cells, the high-temperature processed mesoscopic TiO₂ scaffold is no longer needed. More importantly, a low-temperature solution-processed SnO₂ layer was introduced for electron transportation to substitute the high-temperature sintered dense blocking TiO₂ layer. Our planar solar cells not only have simple geometry with fewer steps to fabricate but also show enhanced performance. The higher efficiency of planar Sb₂S₃ solar cell devices based on a SnO₂ electron conductor is attributed to their high transparency, uniform surface, efficient electron transport properties of SnO₂, suitable energy band alignment, and reduced recombination at the interface of SnO₂/Sb₂S₃.