Molecular Conformational Matching Enables Robust Buried Interfaces in Efficient and Temperature‐Cycling‐Resilient Inverted Perovskite Solar Cells

Temperature fluctuations can disrupt the organization of buried self‐assembled monolayers (SAMs), weaken interfacial contact, and accelerate device degradation. Here, we develop a co‐assembly strategy by incorporating two bisphosphonic acid molecules with distinct linker structures, denoted S1 and S2, into the widely used carbazole‐based SAM [4‐(3,6‐dimethoxy‐9H‐carbazol‐9‐yl)butyl] phosphonic acid (MeO‐4PACz). Compared with S1, S2 exhibits improved conformational compatibility with MeO‐4PACz. The S2/MeO‐4PACz pair also features stronger hydrogen bonding and π–π interactions. In addition, S2 possesses a larger molecular dipole and adsorbs more favorably on indium tin oxide. These molecular attributes promote more continuous and spatially uniform coverage. They also strengthen substrate anchoring and homogenize the interfacial potential distribution. The resulting S2‐based co‐assembled SAM (Co‐SAM) provides favorable energy‐level alignment, facilitates hole extraction, and suppresses nonradiative recombination. It also reinforces the buried interface against cyclic thermal stress. Residual stress accumulation is alleviated, interfacial morphology is preserved, and perovskite phase degradation is retarded. Consequently, inverted perovskite solar cells (PSCs) based on the S2 Co‐SAM achieve a power conversion efficiency of 27.01% and retain 92.8% of their initial efficiency after 500 temperature cycles between −40°C and 85°C. Synergistic molecular and interfacial regulation enables efficient and temperature‐resilient inverted PSCs.