Advancing solvent engineering for perovskite solar cells: Diversification, sustainability, and industrialization

Perovskite solar cells (PSCs) have initiated a technological revolution in the field of photovoltaics, with their cost-effectiveness being a major advantage, largely attributable to the ability to employ straightforward solution-based methods for the deposition of high-quality perovskite polycrystalline films. Solvents, as critical media for crystallization, exert a profound influence on both the crystallization process and the ultimate quality of the resulting crystals. Consequently, in the realm of PSCs, extensive research has demonstrated that regulating solvent systems can markedly enhance the crystal quality of perovskite films and improve the photovoltaic performance of PSCs. Therefore, it is imperative to consolidate the advancements in solvent engineering and to explore its future directions for PSCs. Herein, we begin by elucidating the fundamental models of solution crystallization, followed by a detailed examination of the progress in solvent engineering, encompassing the evolution from single solvent systems to more diverse configurations, as well as the shift from toxic solvents to those with lower toxicity or non-toxicity. Furthermore, we gain insights into the intermediate phases, large-area modules, and the cost and recovery aspects from a solvent perspective. Finally, this review concludes the current state of solvent engineering and identifies promising avenues for future research.