Synergistic Bidirectional Crystallization for High-Performance Perovskite Solar Cells

Traditional n-i-p perovskite solar cells (PSCs) have achieved remarkable power conversion efficiencies exceeding 26%, yet their performance and stability remain critically bottlenecked by interfacial voids and detrimental trap states at the buried interface. These structural anomalies fundamentally originate from the conventional top-down crystallization process, where a rapidly formed top crust induces a solvent blockade effect, trapping residual solvents that subsequently evaporate to leave detrimental buried voids. Here, we overcome this kinetic limitation via a synergistic bidirectional crystallization strategy, enabled by a dual-functional molecular linker, diethyl phosphoramidate (DAPE). By strongly anchoring to the SnO₂ substrate and chemically bridging perovskite precursors, DAPE induces a synchronous bottom-up growth front that complements the anti-solvent-induced top-down crystallization. This kinetically reconstructed process maintains open solvent-evasion channels, effectively eliminating the solvent blockade to yield a dense, void-free interface. Consequently, the optimized devices exhibit relaxed residual stress and minimized non-radiative recombination, achieving a champion power conversion efficiency of 26.25% with superior operational stability. Our work underscores the vital role of regulating crystallization kinetics to eliminate physical interfacial anomalies, offering useful insights for the further development of efficient n-i-p PSCs.