Multifunctional Ternary Oxide for Efficient CsPbBr₃ Perovskite Solar Cells on Rigid and Flexible Substrate via All-Low-Temperature Process

Efficient CsPbBr₃ perovskite films and the low-temperature fabrication of electron transport layers (ETLs) are crucial for the commercial viability of CsPbBr₃ perovskite solar cells (PSCs). We present a vapor-assisted solution technique that produces high-quality CsPbBr₃ perovskite films without annealing. Doping ZnO with trivalent metals such as yttrium (Y), antimony (Sb), and iron (Fe) improves the electrical properties and energy alignment with CsPbBr₃. Our experiments show that Sb doping enhances charge extraction and reduces interface carrier recombination to achieve a power conversion efficiency (PCE) of 9.55% in the inorganic CsPbBr₃ PSCs. The optimized device maintains over 90% of its original PCE after 90 days under 65% relative humidity and 65 °C. Additionally, flexible CsPbBr₃ PSCs with an Sb-ZnO ETL achieve a record 6.06% efficiency with remarkable mechanical durability to retain 91.8% of initial PCE after 1000 bending cycles at a 3 mm curvature radius.