Fully Air-Processed Dynamic Hot-Air-Assisted M:CsPbI2Br (M: Eu2+, In3+) for Stable Inorganic Perovskite Solar Cells

Cesium and lead-based mixed-halide (CsPbX3) all-inorganic perovskite solar cells (AI-PSCs) exhibit an excellent thermal stability compared with conventional organic-inorganic hybrid perovskite devices. Here, we have developed a dynamic hot-air-assisted method to obtain highly crystalline, pinhole-free, thick, and uniform black CsPbI2Br films over a square centimeter scale to optimize the performance of the devices and, later, doped it with divalent and trivalent metal ions (M:CsPbI2Br [M stands for the metal ions Eu2+ and In3+]) to enhance even more the stability. These fully air-processed M:CsPbI2Br-based devices exhibit 17.46% power conversion efficiency (PCE) for a small area (0.09 cm2) and a PCE of 15.82% (under reverse scan) for square-centimeter-scale cells with stabilized efficiency of 17.05% and 15.04%, respectively. Interestingly, our unencapsulated AI-PSCs maintain >95% and >75% of initial PCE over 400 h at 65°C and 85°C, respectively, revealing a robustness against thermal stress.