Dual-Protection Strategy for High-Efficiency and Stable CsPbI2Br Inorganic Perovskite Solar Cells

Large opening circuit voltage (V-oc) loss and poor moisture stability have significantly hindered the progress of inorganic perovskite solar cells (IPSCs). Here, we report a dual-protection strategy via incorporating monomer trimethylolpropane triacrylate (TMTA) into CsPbI2Br perovskite bulk and capping the surface with 2-thiophenemethylammonium iodide (Th-NI) to ameliorate the above issues. Benefiting from growth control and effective suppression of both bulk and surface recombination, the resulting devices show a great improved efficiency from 12.17 to 15.58% with a champion V-oc of 1.286 V. Also, the dual-protection strategy endows films with promoted moisture tolerance, and the nonencapsulated device retains 83.4% of its initial efficiency after aging at 25% relative humidity for 1540 h. More importantly, the target device shows good operational stability and reveals the unfallen efficiency after maximum power point tracking for 350 h at 45 degrees C. Our work offers a feasible method to fabricate efficient and stable CsPbI2Br IPSCs for future commercialization.