Responsive Dielectric Polarization Regulates Nonradiative Losses in Perovskite Solar Cells

Nonradiative recombination in perovskite solar cells (PSCs) is fundamentally governed by carrier‐defect interactions, yet existing strategies primarily focus on defect density reduction and interfacial passivation. Here, we establish a guanidinium‐based dielectric strategy to regulate carrier‐defect interaction kinetics in perovskite films. By incorporating guanidinium‐based additives with systematically varied molecular dipole moments and polarizabilities, enhanced dielectric screening is achieved, which weakens carrier‐defect interactions while simultaneously reducing nonradiative loss. Together with multifunctional chemical passivation, this leads to suppressed nonradiative recombination and reduced energy dissipation. As a result, the optimized devices achieve efficiencies of 26.15% and 26.39% for n‐i‐p and p‐i‐n architectures, respectively, along with 25.64% for large area (1 cm 2 ) devices and 23.11% for wide‐bandgap (1.68 eV) PSCs. The devices also exhibit excellent operational, thermal, and ambient stability. This work identifies dielectric regulation of carrier‐defect interactions as a general strategy to minimize energy dissipation and advance PSCs toward their radiative efficiency limits.