Efficient Bidentate Molecules Passivation Strategy for High-Performance and Stable Inorganic CsPbI2Br Perovskite Solar Cells

All inorganic mixed-halide CsPbI 2 Br perovskites with suitable bandgap and superior thermal durability have ignited rising interests in the field of perovskite solar cells (PSCs). However, the serious energy losses derived from deleterious trap-assisted defects–induced notorious nonradiative recombination and inferior moisture durability are still the primary hindrance on the way to develop high-performance CsPbI 2 Br PSCs. Herein, a novel passivation strategy is presented by introducing dual-functionalized bidentate molecule 2-(2′-thienyl)pyridine (2-ThPy) to modulate perovskite crystallization and passivate halogen vacancy defects. Compared with monodentate counterparts, 2-ThPy can anchor Pb 2+ sites via S and N atomic bonding simultaneously, and the synthesized CsPbI 2 Br films exhibit enlarged grain size, show advantages to passivate defect states, and dramatically reduce trap density, thereby lessening the detrimental carrier recombination. Consequently, a champion power conversion efficiency (PCE) of 12.69% with negligible hysteresis is delivered for the fabricated CsPbI 2 Br PSCs treated with 2-ThPy. Moreover, the moisture stability of CsPbI 2 Br PSCs with 2-ThPy is also greatly enhanced, and the device without encapsulation retains 92% of initial PCE value after 30 days aging under 25 °C and 40% relative humidity in ambient environment. The bidentate molecules passivation strategy paves a promising avenue to implement efficient and stable inorganic PSCs.