A novel radical-reaction interruption strategy for enhancing the light stability of perovskite solar cells

Abstract

The stability issues of perovskite solar cells (PSCs), especially illumination stability, have become a bottleneck that limits their further development, which needs urgent attention. Herein, we present a novel strategy for enhancing the illumination stability of PSCs using the radical scavenger of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) to interrupt photoinduced radical decomposition. It is demonstrated that selectively generated triiodide with the addition of TEMPO can obliterate I-deficient phases during crystallization and passivate defects. More importantly, the photochemical decomposition of targeted perovskite polycrystalline films has been observably inhibited by the free-radical elimination effect of TEMPO. By harnessing TEMPO's defect passivation and radical-scavenging effects, target perovskite devices achieve an outstanding power conversion efficiency of 25.03%, maintaining over 90% of their initial efficiency after continuous maximum power point tracking under ISOS-L-2 conditions at 65 °C for 1000 hours. We demonstrate a novel perspective on the management of photochemical behavior in perovskite devices.