Two‐step‐fabricated FAPbI₃‐based perovskites have attracted increasing attention because of their excellent film quality and reproducibility. However, the underlying film formation mechanism remains mysterious. Here, the crystallization kinetics of a benchmark FAPbI₃‐based perovskite film with sequential A‐site doping of Cs⁺ and GA⁺ is revealed by in situ X‐ray scattering and first‐principles calculations. Incorporating Cs⁺ in the first step induces an alternative pathway from δ‐CsPbI₃ to perovskite α‐phase, which is energetically more favorable than the conventional pathways from PbI₂. However, pinholes are formed due to the nonuniform nucleation with sparse δ‐CsPbI₃ crystals. Fortunately, incorporating GA⁺ in the second step can not only promote the phase transition from δ‐CsPbI₃ to the perovskite α‐phase, but also eliminate pinholes via Ostwald ripening and enhanced grain boundary migration, thus boosting efficiencies of perovskite solar cells over 23%. This work demonstrates the unprecedented advantage of the two‐step process over the one‐step process, allowing a precise control of the perovskite crystallization kinetics by decoupling the crystal nucleation and growth process.

中文翻译：

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通过顺序A站点掺杂精确控制钙钛矿的结晶动力学。

两步法制备的基于FAPbI ₃的钙钛矿因其优异的薄膜质量和可再现性而受到越来越多的关注。然而，潜在的成膜机制仍然是神秘的。在此，通过原位X射线散射和第一性原理计算揭示了具有连续A位置掺杂Cs ⁺和GA ⁺的基准FAPbI ₃基钙钛矿薄膜的结晶动力学。掺入铯⁺在第一步骤中从诱导δ-CsPbI一个替代途径₃到钙钛矿的α相，它是能量上高于从碘化铅常规途径更有利₂。然而，针孔形成由于与稀疏δ-CsPbI的不均匀的核₃晶体。幸运的是，掺入GA ⁺在第二工序中，不仅可以促进从δ-CsPbI相变₃钙钛矿α相，而且还通过奥斯特瓦尔德消除针孔熟化和增强的晶界迁移，因而超过23升压钙钛矿太阳能电池的效率％。这项工作证明了两步法相对于一步法的前所未有的优势，它通过使晶体成核和生长过程脱钩，从而可以精确控制钙钛矿的结晶动力学。