Homogenized Self-Assembled Molecules for Inverted Perovskite Solar Cells

Inverted perovskite solar cells (PSCs) have rapidly improved, driven by advancements in self-assembled molecules (SAMs). However, achieving homogeneous SAM coverage on substrates remains challenging, directly impacting device performance and stability. Here, we present (4-(pyren-1-yl)phenyl)phosphonic acid (PhPAPy), a SAM with a rigid aromatic ring structure. Ab initio molecular dynamics (AIMD) simulations reveal that this rigidity limits rotational freedom, promoting a near-vertical molecular orientation on the substrate. Additionally, π-π interactions between the planar pyrene rings enhance molecular packing, forming a homogeneous and dense SAM layer. As a result, the uniform PhPAPy effectively minimizes perovskite-substrate direct contact, enhances the interfacial properties, reduces buried interface defects, and improves both efficiency and stability. With PhPAPy SAM, the assembled inverted PSCs achieve a certified reverse-scanning power conversion efficiency (PCE) of 26.74% and a certified stabilized power output (SPO) efficiency of 26.12% (from National Institute of Metrology in China). These devices retain 95% of their initial efficiency after 2000 h of maximum power point tracking (MPPT) under continuous AM 1.5G illumination at 65 °C and ambient humidity (ISOS-L-2).