Over the past decade, solution-processed organic–inorganic hybrid perovskite solar cells (PSCs) have emerged as a viable alternative to traditional crystalline silicon photovoltaics, with power conversion efficiency (PCE) increasing notably from 3.8% to over 26%. This remarkable advancement is attributed to the unique band structures and exceptional defect tolerance of the hybrid perovskites. The bandgaps in perovskites derive from their antibonding orbitals at both the valence band maximum and conduction band minimum. Consequently, bond breaking creates states away from the bandgap, resulting in either shallow defects or states within the valence band. Despite defect densities up to 10⁶ times higher than single-crystal silicon, polycrystalline perovskite films (<1 μm thick) can still achieve comparable device performance due to their high defect tolerance. Superior photovoltaic performance in perovskite films depends on an efficient wet-chemical process, offering a notable advantage over silicon-based photovoltaic technology. Evidently, solvent characteristics and their potential interaction with perovskites significantly impact crystal growth from precursor inks, subsequent polycrystalline film quality, and the ultimate performance of devices. Understanding solvent properties in relation to film formation processes is essential for informing solvent selection in the emerging perovskite photovoltaics and its future commercialization. In this Account, we present a thorough analysis of solution-processed perovskite films, encompassing the crystallization process and phase transition of perovskite-related solvated complexes, and structure passivation of perovskite phase. We systematically categorize the prevalent solvents utilized in film preparation and outline a solvent roadmap for producing high-quality perovskite films from a chemical perspective, considering their interaction with the perovskite structure. We also address often-overlooked factors in solvent selection in current research. First, middle-polarity dispersion solvents fundamentally govern nucleation and growth kinetics of perovskite solvated films in the solution phase, thereby significantly shaping film morphology. However, control over the solvation interaction between dispersion solvent and perovskite structure for morphology regulation remains insufficient. Second, high-polarity binding solvents interact with the perovskite structure via solvent-involved intermediates, optimizing crystallization kinetics in the solution phase (sol–gel state) and controlling phase-transition kinetics of the intermediate phase. This interaction influences the crystal and structural properties of the resultant perovskite phase though managing the intermediate phase remains challenging. Third, low-polarity modification solvents, combined with functional passivation molecules, are employed to modulate interface energetics of perovskite films by enabling both chemical defect passivation and physical field-effect passivation. However, achieving optimal interface energetics by forming heterojunctions or homogeneous interfaces through solvent selection is still difficult. By integrating fundamental solvent mechanisms and design criteria, comprehensive strategies can be formulated to achieve high PCE and stability in photovoltaics. Finally, we discuss key challenges and future perspectives in commercializing solution-processed perovskite photovoltaics, with the goal of inspiring innovative material designs and solvent engineering approaches.

中文翻译：

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优化溶剂化学以获得高质量的卤化物钙钛矿薄膜


在过去的十年中，溶液加工的有机-无机杂化钙钛矿太阳能电池 （PSC） 已成为传统晶体硅光伏的可行替代品，功率转换效率 （PCE） 从 3.8% 显着提高到 26% 以上。这一显着的进步归功于杂化钙钛矿独特的能带结构和出色的缺陷容忍度。钙钛矿中的带隙来自它们在价带最大值和导带最小值处的反键轨道。因此，键断裂会在远离带隙的地方产生状态，从而导致浅缺陷或在价带内产生状态。尽管缺陷密度比单晶硅高 10^{到 6} 倍，但多晶钙钛矿薄膜（<1 μm 厚）由于其高缺陷容忍度，仍然可以实现相当的器件性能。钙钛矿薄膜的卓越光伏性能取决于高效的湿化学工艺，与硅基光伏技术相比具有显着优势。显然，溶剂特性及其与钙钛矿的潜在相互作用会显著影响前驱体油墨的晶体生长、随后的多晶薄膜质量以及器件的最终性能。了解与成膜过程相关的溶剂特性对于为新兴钙钛矿光伏中的溶剂选择及其未来的商业化提供信息至关重要。在本账户中，我们对溶液处理的钙钛矿薄膜进行了全面分析，包括钙钛矿相关溶剂化复合物的结晶过程和相变，以及钙钛矿相的结构钝化。 我们系统地对薄膜制备中使用的常用溶剂进行分类，并从化学角度概述了生产高质量钙钛矿薄膜的溶剂路线图，同时考虑它们与钙钛矿结构的相互作用。我们还解决了当前研究中溶剂选择中经常被忽视的因素。首先，中等极性分散溶剂从根本上控制钙钛矿溶剂化薄膜在溶液相中的成核和生长动力学，从而显着塑造薄膜形态。然而，对分散溶剂和钙钛矿结构之间的溶剂化相互作用对形态调节的控制仍然不足。其次，高极性结合溶剂通过溶剂涉及的中间体与钙钛矿结构相互作用，优化溶液相（溶胶-凝胶状态）中的结晶动力学并控制中间相的相变动力学。这种相互作用会影响所得钙钛矿相的晶体和结构特性，尽管管理中间相仍然具有挑战性。第三，低极性改性溶剂与功能性钝化分子相结合，通过实现化学缺陷钝化和物理场效应钝化来调节钙钛矿薄膜的界面能量。然而，通过溶剂选择形成异质结或均相界面来实现最佳界面能量仍然很困难。通过整合基本的溶剂机制和设计标准，可以制定全面的策略，以实现光伏的高 PCE 和稳定性。 最后，我们讨论了溶液处理钙钛矿光伏商业化的主要挑战和未来前景，目的是激发创新的材料设计和溶剂工程方法。