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 & alpha;-cyano-4-hydroxycinnamic acid (CHCA) molecule with multiple functional groups including -COOH, -OH, and -C & EQUIV; N is adopted to manipulate buried interface. Due to simultaneous interaction of multiple groups in CHCA with SnO2 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. The & alpha;-cyano-4-hydroxycinnamic acid with -COOH, -OH, and -C & EQUIV; N groups was adopted to modify the buried interfaces of perovskite solar cells (PSCs), resulting in an elevated power conversion efficiency (PCE) from 21.26% to 23.02%, and the unsealed PSC maintains 94.2% of original PCE after 1500 h at 15-20% relative humidity.image & COPY; 2023 WILEY-VCH GmbH