Alleviating Passivating Molecule Self-Aggregation and Interfacial Non-Radiative Recombination for High-Performance Two-Dimensional Metal Halide Solar Cells

Two-dimensional metal halides paired with organic active layers form p/n interdigitated heterojunctions that offer broad potential owing to their high stability and extended spectral response. However, inherent defect states at p-type interface frequently cause severe charge accumulation and require efficient passivation. PDAI₂ enables passivation via its strong electrostatic potential and dipole moment, yet inevitably induces severe self-aggregation. Thus, we develop a synergistic molecular passivation strategy by introducing CyPAI with a rigid cyclopropyl group into PDAI₂ system. Owing to its weaker electrostatic potential and steric hindrance, CyPAI disrupts the hydrogen-bond network of PDAI₂, enabling compact and high-coverage passivation. This strategy suppresses interfacial non-radiative recombination, while the reconstructed interfacial dipole moment markedly accelerates the cross-interface extraction kinetics of photogenerated carriers. Meanwhile, the ordered interdigitated p/n heterojunction constructed via nanoimprinting further enhances light trapping and interfacial contact. The optimized devices achieve a champion PCE of 24.34% and a remarkable FF of 85.36%, which is the record value for two-dimensional metal halide solar cells so far. Notably, unencapsulated devices retain over 92% of their initial efficiency after 2,000 h of MPP tracking under 1-sun illumination, demonstrating that this synergistic strategy effectively boosts both the high efficiency and excellent operational stability of p/n heterojunction devices.