A facile interface engineering method to improve the performance of FTO/ZnO/CsPbI3−xBrx (x < 1)/C solar cells.

Hole-transport-layer (HTL)-free, carbon-based all-inorganic perovskite solar cells (PSCs) are attracting a great interest owing to a low cost and an advanced stability in ambient environment. However, the photoelectric conversion efficiency (PCE) for this kind of PSCs was far lower than expected. Interface engineering is a promising method to enhance PSCs efficiency through improving the interface charge transfer. In our work, we introduce a simple, clean interfacial engineering method of deionized water (DI) spin-coating to treat the F-doped SnO₂ (FTO). And then ZnO was spin-coated on the treated FTO. A compact and highly uniform ZnO film was obtained. Excess CsBr was added into CsPbI₃ precursor solution to obtain stable black phase CsPbI₃ at a low temperature (120 °C). HTL-free, carbon-based all-inorganic CsPbI_3−xBr_x (x < 1) perovskite solar cells are fabricated with the structure of FTO/DI/ZnO/CsPbI_3−xBr_x (x < 1)/C. After DI treatment, the defect density of device is greatly decreased so that carriers transport at the interface is accelerated and the charge recombination is effectively suppressed. The champion PCE has been improved from 10.95 to 12.39%, obtaining an improved PCE about 13%, which is the highest PCE for HTL-free, carbon-based all-inorganic PSCs until now. [ABSTRACT FROM AUTHOR]