Lithium‐Ion Endohedral Fullerene (Li⁺@C₆₀) Dopants in Stable Perovskite Solar Cells Induce Instant Doping and Anti‐Oxidation

Abstract

Herein, we report use of [Li⁺ @C₆₀ ]TFSI^- as a dopant for spiro-MeOTAD in lead halide perovskite solar cells. This approach gave an air stability nearly 10-fold that of conventional devices using Li⁺ TFSI^- . Such high stability is attributed to the hydrophobic nature of [Li⁺ @C₆₀ ]TFSI^- repelling moisture and absorbing intruding oxygen, thereby protecting the perovskite device from degradation. Furthermore, [Li⁺ @C₆₀ ]TFSI^- could oxidize spiro-MeOTAD without the need for oxygen. The encapsulated devices exhibited outstanding air stability for more than 1000 h while illuminated under ambient conditions.