Ionic Liquid-Based Perovskite Solar Cells: A Decade Review and Reassessment of Their Greenness

Abstract

Over the past decade, perovskite solar cells (PSCs) have developed rapidly, with the certified PCEs of single-junction devices now exceeding 27.5%, comparable to those of single-junction silicon solar cells. However, large-scale commercialization remains limited by factors such as the toxicity of solvents and heavy metals, as well as the long-term instability of perovskite layers. At present, the fabrication of high-efficiency PSCs relies heavily on toxic solvents, including N,Ndimethylformamide (DMF) and dimethyl sulfoxide (DMSO), and is critically dependent on antisolvent treatment, thereby posing significant challenges for industrial production and environmental sustainability. Meanwhile, low-toxicity and non-toxic solvents applicable to perovskite precursor solutions have been increasingly explored. Among them, ionic liquids (ILs) have attracted growing attention due to their low volatility, tunable acidity and composition, and strong interactions with B-site metal ions in perovskites, such as Pb and Sn. This review traces the evolution of PSCs employing ionic liquids as solvents in perovskite precursor solutions and discusses the potential breakthroughs and challenges of ionic-liquid-based solvent systems.