The multi-scale chemical phase heterogeneity of halide perovskites seriously affects the physical functional integrity of semiconductors and the performance of photovoltaic devices. However, the phase homogeneity in two-step-method perovskites (TSPs) has rarely been investigated. Here, we elaborate on the severe heterogeneity of the FAMA-based TSP film and found that residual PbI₂ crystallites and Pb⁰ species accumulate at the top while a Cl/MA-rich interface is present at the bottom, impeding carrier nonequilibrium transport in the vertical direction. The homogeneity of the TSP film is reinforced by chemical tailoring with 4-methoxyphenethyl ammonium chloride, thus achieving superior structural stability and a charge carrier balance dynamic process. The target TSP p–i–n device achieves a recorded power conversion efficiency of 25.12% under 1-sun illumination (certified at 24.01%). This study uncovers the hidden physicochemical properties of the TSP film, guiding the understanding of microscopic homogeneity and functional integrity and the design of efficient two-step-method inverted perovskite solar cells.

中文翻译：

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两步法卤化物钙钛矿光伏中的相均匀性介导的电荷载流子平衡


卤化物钙钛矿的多尺度化学相异质性严重影响半导体的物理功能完整性和光伏器件的性能。然而，两步法钙钛矿 （TSP） 中的相均匀性很少被研究。在这里，我们详细阐述了基于 FAMA 的 TSP 薄膜的严重异质性，发现残留的 PbI₂ 微晶和 Pb⁰ 物质在顶部积累，而富含 Cl/MA 的界面存在于底部，阻碍了载流子在垂直方向上的非平衡传输。TSP 膜的均匀性通过与 4-甲氧基苯乙基氯化铵的化学定制得到加强，从而实现了卓越的结构稳定性和电荷载流子平衡动态过程。目标 TSP p-i-n 器件在 1 个太阳光照射下实现了 25.12% 的记录功率转换效率（认证为 24.01%）。本研究揭示了 TSP 薄膜隐藏的物理化学性质，指导了对微观均匀性和功能完整性的理解以及高效的两步法倒置钙钛矿太阳能电池的设计。