Anisole as a Green Solvent Alternative for [6]‐Phenyl‐C ₆₁ ‐Butyric Acid Methyl Ester in Ambient‐Processed p–i–n Perovskite Solar Cells and Flexible Minimodules

The use of chlorinated solvents such as chlorobenzene for PCBM processing in perovskite solar cells (PSCs) raises environmental and occupational safety concerns. Here, anisole is proposed as a green solvent alternative for PCBM deposition in p-i-n PSCs and flexible minimodules. By optimizing the ink concentration, uniform PCBM layers were obtained with an optimal thickness of 38 nm and a low surface roughness of 4.88 nm. This resulted in reduced series resistance (R1 = 12.48 Ω vs. 13.26 Ω for CB) and a lower ideality factor (1.34 vs. 1.41), enabling efficient interfacial charge extraction and power conversion efficiencies up to 15.98%. Devices retained 95% of their initial PCE after 1100 h under ISOS-D1I and showed improved thermal stability (T₈₀ = 96 h), confirming that solvent substitution does not introduce additional degradation pathways. Furthermore, anisole-based inks were compatible with slot-die coating in roll-to-roll processing, achieving 7.04% efficiency in flexible devices. These results highlight anisole as a safer and greener solvent alternative to chlorobenzene, combining high performance, enhanced stability, and scalability, making it a promising candidate for more sustainable perovskite solar cell manufacturing.