Green Solvent Enabled Perovskite Ink for Ambient‐Air‐Processed Efficient Inkjet‐Printed Perovskite Solar Cells

Abstract Perovskite ink based on a green or non‐toxic solvent meets industrial requirements for efficient perovskite solar cells (PSCs). Perovskite inks must be developed with non‐toxic or involve the limited use of toxic solvents to fabricate efficient inkjet‐printed (IJP) perovskite photovoltaics. Herein, γ‐valerolactone is used as a solvent with a low environmental impact, and the strategy showed category 3 toxicity, even with a small quantity of toxic solvents employed to dissolve the perovskite salts. The structural, optical, and electronic properties of IJP perovskite films are improved by adding 1,3‐dimethyl‐2‐imidazolidinone (DMI) to the green perovskite ink. The IJP perovskite films developed by green solvents with 15% (volume %) of DMI exhibited high thickness uniformity (≈97%), and thicker and smoother surfaces than their counterparts. An additive‐modified IJP‐PSC device achieved a maximum power conversion efficiency (PCE) of 17.78%, higher than that of an unmodified device (14.75%). The performance of the IJP‐PSC device is superior primarily because of its exceptional film‐thickness homogeneity, larger grains, and appropriate structures. These attributes significantly decreased unwanted reactions of the perovskite with solvents, ensuring phase purity and enhancing overall efficiency. The innovative green‐solvent ink‐engineering strategy for producing large‐scale perovskite films shows great promise for advancing perovskite solar module technology (with PCE of 13.14%).