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, gamma-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 (approximate to 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%).
