Interfacial Molecular Engineering With Insoluble Multifunctional Modifiers for Perovskite Solar Cells

ABSTRACT Achieving uniform crystallization at both the top and buried interfaces of perovskite films is critical for unlocking their full photovoltaic potential, yet has long been hindered by asymmetric crystallization kinetics and interfacial defects. To tackle this challenge, we developed an interfacial molecular engineering strategy that enables in situ formation of a functional passivation layer at the SnO ₂ /perovskite buried interface. This layer, rich in multiple electronegative sites, not only effectively passivates surface defects on the electron transport layer but also profoundly regulates perovskite nucleation and crystal growth. Characterization results confirm that during subsequent exposure to the perovskite precursor solution, the passivation layer remains chemically and structurally intact—neither dissolving nor incorporating into the perovskite lattice—thus preserving its interfacial functionality without compromising the intrinsic optoelectronic properties of the perovskite. Leveraging these advantages, the optimized device attained a power conversion efficiency of 21.7%, representing an approximate 5% improvement compared to the control group. This work presents a simple yet highly effective approach to buried‐interface passivation, significantly enhancing device performance and reproducibility.