Green Solvents Enable Annealing‐Free Fabrication of Carbon‐Based Printable Mesoscopic Perovskite Solar Cells

Conventional polar solvents used in fabricating printable mesoscopic perovskite solar cells (p‐MPSCs) under ambient conditions present significant health and environmental risks. Adopting green solvents is therefore crucial not only for mitigating these hazards but also for facilitating the low‐cost production of p‐MPSCs. Herein, we introduced green solvents N,N‐dimethylacetamide (DMAc) and 1,2‐dimethoxyethane (DME) into an annealing‐free fabrication process for p‐MPSCs. N‐methyl‐2‐pyrrolidone (NMP) was further incorporated to optimize the balance between the solvation capability of the mixed solvents and the crystallization kinetics of the perovskite. Comparative studies revealed that different solvent combinations distinctly influence perovskite crystallization behavior and film morphology during the annealing‐free process. Ultimately, champion power conversion efficiencies (PCEs) of 17.80% and 14.12% were achieved via this annealing‐free route using DMAc/NMP and DME/NMP mixed solvents, respectively. Remarkably, DMAc/NMP‐based devices retained 95% of their initial PCE after 87 days of storage under ambient conditions (30°C ± 5°C, 45% ± 5% RH), demonstrating excellent long‐term stability.