Learning from plants: Introducing natural antioxidants to resist superoxide radicals in perovskite solar cells

Superoxide radicals (O₂^•-) are generated on the surface of classic perovskite (MAPbI₃) during exposure to light and oxygen (light/O₂), which results in rapid surface degradation. We found that O₂^•--induced degradation occurs at the top and bottom interfaces of Cs_0.175FA_0.75MA_0.075PbI₃ (PVSK) and that the degradation of the bottom is mostly responsible for the nonexposed air aging process of SnO₂-based perovskite solar cells (PSCs). Plants in nature can usually produce antioxidants to alleviate aging caused by O₂^•-. Inspired by this natural process, a fullerene vitamin A derivative (C₆₀RTL) was designed to be used as a buffer layer between SnO₂ and PVSK to remove O₂^•- and eliminate degradation at the PVSK film's lower interface. This buffer layer reduced the defect density of states, accelerated the transfer of photogenerated electrons, and significantly minimized poor contact at the SnO₂/perovskite interface. In addition, introducing natural antioxidant xanthophyll into perovskite could inhibit the production of O₂^•-, passivated grain boundaries, and reduced trap density. This work was inspired by the natural antioxidants used by plants to combat the attack of O₂^•-, which provides a fresh idea for producing efficient and long-lasting PSCs.