Volatile solution: the way toward scalable fabrication of perovskite solar cells?

In the past decade, perovskite photovoltaics have achieved impressive progress in both efficiency and stability, bringing new insights and excitement in industrial sectors. Transitioning this technology from the laboratory to the industrial level first needs to overcome the crucial barrier of scalable fabrication. Although various synthetic routes have been developed for obtaining high-quality perovskite layers, there remains a gap between small-scale fabrication and industrial-level manufacturing, as the incumbent processing usually requires complex and energy-consuming treatments to remove the non-volatile solvents from those conventional perovskite inks. In this perspective, we conceptualize the volatile solution as an alternative ink system serving as a roadmap toward reliable manufacturing in the future. We discuss, starting from crystallization thermodynamics to insights into the chemistry ink system, its compatibility with various deposition techniques, and the analytic feasibility of scalable/stream-lined manufacturing using this new ink system. With this comprehensive minireview on the ongoing research and a discussion of its hypothetical potential/challenge, we hope to bring new inspiration and to catalyze the transition. Non-volatile solvents, such as DMF, DMSO, and NMP, have been traditionally utilized as the solvent medium to dissolve perovskite salts. As a result, post-treatments are inevitably applied to expedite the removal of the solvents for crystallization of the perovskite. In the laboratory, the complicated and delicate post-treatments can be compatible with the fabrication of small-sized devices. Nevertheless, with regard to industrial manufacturing, it is a challenge to transfer the post-treatments into stream-lined production due to the variables in the process. This scenario can be changed if the non-volatile solvents are replaced by volatile solvents, with the attendant consequences of post-treatments being eliminated, thus enabling simple and fast fabrication of perovskites. This perspective conceptualizes the volatile solution and then analyzes the crystallization kinetics, film deposition, and feasibility of stream-lined manufacturing using volatile solvents. We expect that this perspective could inspire innovations for the industrialization of perovskite solar cells. The use of volatile solvents (VSs) as the new dissolving medium for synthesis of perovskites has attracted increasing attention. The high volatility of VSs eliminates the post-treatment for solvent removal and enables fast crystallization, and simple and high-speed deposition of high-quality perovskite layers, which is compatible with industrial manufacturing. This perspective analyzes the crystallization kinetics, film deposition, and the feasibility of stream-lined manufacturing using VSs. We hope to bring new inspiration and to catalyze the transition to perovskite solar cells.