Interface Modification by FAI@ZIF-8 for High-Efficiency Perovskite Solar Cells

The efficiency of perovskite solar cells (PSCs) has surpassed all other thin-film solar cells. It is well known that the mismatch between the perovskite film and electron transport layer is an important factor to damage the stability of PSCs. Herein, an effective modification strategy to improve stability by using FAI@ZIF-8 is demonstrated. It is found that the FAI@ZIF-8 modification reduces the trap-state density of the perovskite by slowly releasing FAI from the ZIF-8 pore. Besides, FAI@ZIF-8 improves energy-level alignment at TiO2/perovskite interface, which facilitates electron extraction at the interface. As a consequence, an optimal power conversion efficiency (PCE) of 23.52% is achieved for the FAI@ZIF-8-treated PSCs. After storing under 20-30% relative humidity and room temperature for 2000 h, the FAI@ZIF-8-treated device sustains 96% of its initial PCE; nevertheless, the control device maintains only 73% of its initial PCE under the same conditions. This strategy is helpful to guide the development of high-performance PSCs and promotes commercialization of perovskite materials.