Disrupting Solvent Self‐Association via Dipole–Dipole Interactions for Improved Performance of Perovskite Solar Cell

ABSTRACT High‐quality perovskite films demand strongly coordinating solvents (SCS, e.g., DMSO, NMP) for crystal growth regulation, yet such solvents often leave residue and induce notorious voids. Prior work elucidated the voids distribution along the vertical direction but cannot explain their lateral dimensions and spatial patterning. Here, we find that the hundreds‐of‐nanometer lateral dimension and clustered morphology of buried voids originate from the self‐association of SCS. The tailored‐made 1‐bromo‐4‐dimethylphosphoryl‐benzene (BPPO) with inherently weak intermolecular interaction is introduced, which mainly exists in a monomeric form and can efficiently modify the buried interface by constructing dipole‐dipole interactions with SCS. The self‐association is disrupted, enabling uniform SCS distribution rather than forming big cluster, which accelerates the escape and ultimately eliminates voids at the buried interface. Perovskite solar cells (PSCs) based on BPPO show an efficiency increase from 25.2% to 27.2% (certified efficiency of 27.0%, aperture area of 0.0712 cm 2 ), with improved stability under ISOS‐D‐2 and ISOS‐L‐2 protocols. Furthermore, the BPPO‐modified perovskite solar module (PSMs, aperture area of 17.4 cm 2 ) achieved an efficiency of 24.2%, demonstrating its excellent scalability.