Stabilizing Perovskite Solar Cells Based on 2,2′,7,7′‐Tetrakis(N,N‐DI‐P‐Methoxyphenylamine)‐9,9′‐Spirobifluoren with Perfluoropolyethers

Abstract

Organic–inorganic hybrid perovskites in combination with the hole‐transport material (HTM) 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluoren (spiro‐OMeTAD) yield impressive power conversion efficiency (PCE) in n–i–p perovskite solar cells (PSC). To ensure sufficient hole extraction from the perovskite absorber to the metal electrode, the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) doping is considered indispensable to promote spiro‐OMeTAD oxidization and obtain consequently enhanced conductivity. However, LiTFSI‐doped spiro‐OMeTAD usually leads to a reduced stability of PSCs because of the hygroscopic nature of LiTFSI, which further limits its potential commercialization. Herein, a hydrophobic material, namely perfluoropolyethers (PFPEs), is used as surface modifier of doped HTM to improve both efficiency and stability of PSCs. It is revealed that the introduction of PFPE increases the concentration of positive radicals, enhances charge‐carrier transport, and improves stability of PSCs under wetting stress. Moreover, the device based on PFPE achieves a champion PCE of 21.94%. In these findings, valuable insights are provided for the future commercialization of PSCs.