Perovskite Quantum Dots Exhibiting Strong Hole Extraction Capability for Efficient Inorganic Thin Film Solar Cells

Inorganic semiconductor Sb2(S,Se)3 possesses a suitable bandgap, environmentally benign elemental composition, and excellent stability, offering ample promise for next-generation low-cost solar cells. Here, we demonstrate that perovskite quantum dots (QDs), including CH3NH3PbBr3 and CsPbBr3, can serve as highly efficient and air-stable hole extraction materials in Sb2(S,Se)3 solar cells. Through a proper pre-treatment of the colloidal QDs, a 25-nm-thick QD film can be obtained with excellent uniformity and charge transport properties. Spectroscopic and photoelectrochemical analysis show that perovskite QDs can effectively extract holes from Sb2(S,Se)3 with suppressed carrier recombination. The perovskite QDs/Sb2(S,Se)3 heterojunction also establishes an increased built-in potential so that open-circuit voltage is pronouncedly enhanced. Finally, the device based on perovskite QDs/Sb2(S,Se)3 heterojunction boosts the efficiency from 4.43% to 7.82%, setting a record value, to the best of our knowledge, in Sb2(S,Se)3 solar cells. Our research manifests another application of perovskite materials and practical strategy toward efficiency improvement of Sb2(S,Se)3 solar cells.