Specially functionalized fullerene repairs attack sites of superoxide radicals, achieving high-performance perovskite solar cells

Superoxide radicals (O 2 − ) generated on the surfaces of hybrid organic–inorganic perovskites (PVSK) and at the SnO 2 /PVSK interface induce rapid degradation at buried interfaces and grain boundaries (GBs). Herein, we introduce a synergistic protection strategy for the attack sites of O 2 − on PVSK. This strategy combines a fullerene alpha-trithiophene derivative (C 60 TPN) buffer layer with a fullerene propanedihydrazide derivative (C 60 PDD) additive to absorb O 2 − and eliminate the degradation caused by O 2 − . C 60 TPN serves as a buffer layer between SnO 2 and PVSK, inhibiting the generation of O 2 − at the SnO 2 surface and eliminating degradation at buried interfaces, reducing the defect density of states, accelerating the transfer of photogenerated electrons, and remarkably reducing poor contact at the SnO 2 /PVSK interface. In addition, introducing C 60 PDD into PVSK to stitch GBs suppresses the generation of O 2 − , resists the invasion of O 2 − , and reduces trap density. Results indicate that the synergistic anti-O 2 − strategy based on fullerene derivatives remarkably improves the stability and photoelectric conversion efficiency of the target devices. This work emphasizes the importance of eliminating O 2 − -induced degradation at GBs and buried interfaces in the development of stable and efficient PVSK solar cells (PSCs).