Uniform and Robust NiO x /SAM Layer in Perovskite Solar Cell via Multifunctional Crown Ether Modification

The combination of self‐assembled molecules (SAMs) and nickel oxide (NiO x ) has recently become one of the basic structures for achieving high‐performance inverted perovskite solar cells (PSCs). However, the dissolution of SAM and other modification additives caused by subsequent coating often leads to failure of the modification on NiO x . Meanwhile, it remains difficult to directly optimize the performance of NiO x . Herein, we introduce a modification strategy by directly incorporating a crown ether named 4′‐Carboxybenzo‐18‐Crown‐6‐Ether ( Crown ) into NiO x precursor, aiming to prevent modification failure simultaneously suppressing defects within the buried perovskite interface. This strategy facilitates the dissolution of NiO x nanoparticles in the precursor, resulting in a smoother surface morphology and a reduction of highly oxidative Ni 4+ species. Furthermore, the carboxyl groups in the Crown , together with the optimized NiO x surface, enhance the anchoring of SAM on NiO x , resulting in a more uniform SAM that is highly resistant to solvent washing. Ultimately, the optimized NiO x /SAM combination provides an exceptional perovskite buried interface. Benefiting from these superior interfacial properties, the Crown ‐modified PSCs based on perovskite (1.68 eV) achieve a power conversion efficiency (PCE) of 23.05%, with 1 cm 2 device reaching 20.63%. Moreover, the Crown ‐modified devices exhibit enhanced photostability, retaining 74% of initial efficiency.