Reinforcing Coverage of Self‐assembled Monomolecular Layers for Inverted Perovskite Solar Cells with Efficiency of 25.70 %

Abstract Self‐assembled monolayers (SAM) as hole transport layers have been widely used in high‐efficiency inverted perovskite solar cells (PSCs) exceeded 26 %. However, the poor coverage and non‐uniform distribution on the substrate of SAM further restrict the improvement of device performance. Herein, we utilize the mixed SAM strategy via the MeO‐2PACz along with perfluorotripropylamine (FC‐3283) to improve the SAM coverage, aiming to accelerate the carrier transport, promote the perovskite growth, regulate the surface energy levels and suppress the nonradiative recombination. The champion device with the mixed‐SAM achieves an efficiency of 25.70 % (certified efficiency of 25.6 %) with long‐term stability (maintained the initial efficiency of 90 % after 1000 h and 180 h under ISOS‐L‐1 and ISOS‐L‐2).