Bifunctional Passivation for Efficient and Stable Low-Temperature Processed All-Inorganic CsPbIBr2 Perovskite Solar Cells

Carbon-based all-inorganic CsPbIBr 2 perovskite solar cells (PSCs) have attracted a lot of attention due to their simple fabrication process and good thermal stability. But the efficiency of devices is lower due to the poor quality of the solution-processed CsPbIBr 2 film. A high-quality CsPbIBr 2 film with large grain size , good crystallinity and reduced trap-state density is necessary for efficient PSCs. In this work, fluorine-containing trifluoroethyl methacrylate (TFEMA) is employed to improve the microstructure and photoelectrical properties of the low-temperature processed CsPbIBr 2 film. Our all-inorganic PSCs consist of the FTO/TiO 2 /CsPbIBr 2 /carbon simple structure. The power conversion efficiency (PCE) of the modified PSCs using TFEMA (TFEMA-PSCs, 8.54%) is much higher than 31.8% of the Reference-PSCs (6.48%) and an open-circuit voltage (V oc ) of 1.305 V was achieved. The reasons for the improved performance have been systematically investigated. The characterizations show that the enhanced PCE in the TFEMA-PSCs can be ascribed to the optimized microstructure, decreased carrier recombination, reduced trap-state density and promoted charge transfer. This work provides an effective and facile strategy to prepare high-quality CsPbIBr 2 films by low-temperature process.