Perovskite solar cells (PSCs) have garnered considerable attention for their ability to deliver high-power conversion efficiencies through economical, solution-processed fabrication. However, reliance on toxic solvents such as N, N-dimethylformamide (DMF) and the antisolvent-dripping method poses challenges for large-scale manufacturing. This study presents an antisolvent-free, one-step spin-coating method for fabricating CH (NH 2) 2 1-x Cs x PbI 3 (FA 1-x Cs x PbI 3) perovskite films using a volatility-controlled cosolvent. Using 2-methoxyethanol (2-ME) as a highly volatile primary solvent to drive rapid supersaturation, while 1-cyclohexyl-2-pyrrolidone (CHP) acts as a high-boiling-point cosolvent to moderate crystallization kinetics through intermediate stabilization. Crucially, CsCl is introduced as a strategic additive to overcome the inherent low solubility of conventional cesium precursors in 2-ME. CsCl appears to play dual roles: enabling effective Cs + incorporation to stabilize the α-phase perovskite and likely assisting crystallization by facilitating the formation of transient chloride-mediated intermediates. Optimizing the formulation with 3. 5 vol% CHP and 7. 5 mol% CsCl led to significant improvements in film uniformity, crystallinity, and optical properties. Consequently, n-i-p planar heterojunction solar cells fabricated using a 0. 45 M precursor solution achieved a high-power conversion efficiency of 21. 1% with short-circuit current density (25. 8 mA/cm 2), open-circuit voltage (1. 06 V), and fill factor (77. 5%), and a stabilized output of 20. 8%, confirming the potential of this DMF- and antisolvent-free process for scalable PSC production, while emphasizing that the present approach is based on volatility control rather than complete solvent detoxification. • Developed a DMF- and antisolvent-free one-step perovskite fabrication method • Utilized 2-methoxyethanol as the primary solvent with a CHP cosolvent • Improved film uniformity and crystallinity via CsCl additive incorporation • Achieved 21. 1% power conversion efficiency in n-i-p planar solar cells • Promotes scalable perovskite solar cell production
Ryo Ishikawa (Fri,) studied this question.