Cadmium doping for improving the efficiency and stability of carbon-based CsPbIBr2 all-inorganic perovskite solar cells

The all-inorganic perovskite CsPbIBr2 is a promising material in the photovoltaic (PV) field due to its acceptable optical bandgap and favorable air-stable phase stability. However, the conventional solution-processed poor-coverage thin films make it a challenging task to prepare high-performance solar cells. In this work, we introduce cadmium ions (Cd2+) into CsPbIBr2 perovskite and investigate how this doping treatment would affect the PV performance of the carbon-based CsPbIBr2 all-inorganic perovskite solar cells (FTO/SnO2/CsPbIBr2/carbon). We found that the crystallinity and morphology of CsPbIBr2 thin films are significantly improved after Cd2+ doping, leading to improved light absorption and carrier transportation with reduced carrier recombination in perovskites. The optimized device achieved the highest efficiency of 6.79% in comparison with 4.36% for the device without Cd2+ doping, an increase of 56% in efficiency. Meanwhile, the optimized device with Cd2+ doping exhibited enhanced stability (76% of initial efficiency after 10 hours) in ambient atmosphere. Furthermore, the whole fabrication process of these devices is performed at low temperatures, not more than 160 °C. The present work provides a simple and economical strategy for the fabrication of low-temperature-processed CsPbIBr2 solar cells and the improvement in their performance.