Minimizing Buried Interface Nonradiative Recombination Losses by Multifunctional Chemical‐Bridging Molecules Enables Efficient Perovskite Solar Cells

Minimizing the buried interface carrier nonradiative recombination loss has been a great challenge in the field of perovskite solar cells. Herein, a multifunctional chemical‐bridging strategy is reported where the α ‐cyano‐4‐hydroxycinnamic acid (CHCA) molecule with multiple functional groups including −COOH, −OH, and −C ≡ N is adopted to manipulate buried interface. Due to simultaneous interaction of multiple groups in CHCA with SnO 2 and perovskite layers, interfacial contact is ameliorated. The double‐sided chemical anchoring by CHCA enables interfacial defect passivation, residual tensile strain mitigation, reduced interfacial energy barrier, and improved perovskite crystallization. Through this ingenious chemical‐linking strategy, the power conversion efficiency is much increased from 21.26% to 23.02%, which is owing to much suppressed buried interface nonradiative recombination. The unsealed modified devices demonstrate enhanced moisture stability, degrading by less than 6% after 1500 h of aging under the relative humidity range of 15–20%. In this work, a way for minimizing buried interfacial nonradiative recombination losses through the rational design of versatile chemical‐bridging molecules with the synergy of multiple functional groups is provided.