Morphology evolution of ultra-stable and low-cost all-inorganic lead-free perovskite solar cells

The emergence of all-inorganic lead-based perovskite solar cells (PSCs) has generated enormous interest in the perovskite research community. The presence of lead (Pb) in these devices, however, has caused some challenges because of its high toxicity, which slows down or even hinders their commercialization. Here we report the successful fabrication of all-inorganic Pb-free PSCs with environment-friendliness, low cost, and excellent stability. In such devices, novel Cs3Sb2I9 perovskite films were prepared by a solution-based method, which possess high-quality morphology, long carrier lifetime, low defect density, and a well-matched band structure with other functional layers. Additionally, carbon electrodes were introduced to replace the labile organic components and expensive noble metal electrodes commonly seen in the traditional PSCs. As a result, the all-inorganic Pb-free PSCs exhibit a champion PCE of 1.43%, which is more than two times higher than the results from previous reports. More importantly, the all-inorganic Pb-free PSCs demonstrated excellent stability under various extreme conditions, such as constant illumination, high humidity, and high temperature. This study provides very useful insights into the development of next-generation commercial PSCs with environment-friendliness, low cost, and excellent stability.