Dual additive strategy for ambient blade-coated MAPbI3 using a green ionic liquid solvent: towards fully printable perovskite solar cells with carbon electrodes

Abstract

In this study, a blade-coating technique was used to deposit MAPbI₃ perovskite films using methylammonium acetate (MAAc), a green protic ionic liquid, under ambient conditions. Replacing toxic solvents like dimethyl formamide and dimethyl sulfoxide with MAAc significantly reduces environmental and safety concerns for large-scale production. To enhance crystallization quality, two chloride-based additives—methylammonium chloride (MACl) and dodecylpyridinium chloride (DPCl)—were added to the precursor ink. Optimized coating parameters, combined with vacuum-assisted crystallization and these additives, resulted in uniform perovskite layers with larger crystal grains and fewer defects. MACl and DPCl improved charge carrier dynamics by reducing defect states, suppressing non-radiative recombination, and enhancing light absorption, as confirmed by multiple analyses. The optimized device structure, FTO/c-TiO₂/m-TiO₂/Perovskite/nanoparticles HTL/carbon back contact, incorporating the dual additive, exhibits a 78% enhancement in power conversion efficiency—rising from 8.90% for the control to 15.88% for the optimized. Additionally, the unencapsulated devices demonstrated excellent storage stability under ambient conditions. Notably, all fabrication steps occurred in uncontrolled environments with a relative humidity of about 45%, demonstrating the robustness and real-world applicability of this eco-friendly method.