Regulating Precursor Viscosity with Inert Solvent Additives for Efficient Blade‐Coated Perovskite Solar Cells

Abstract Metal halide perovskite solar cells (PSCs) are emerging as promising candidates for next‐generation photovoltaics aimed at green energy production. However, during solution‐processed film deposition, the distinct rheological behaviors of blade coating, compared to spin coating, result in less controlled crystallization, leading to inferior film quality and limiting the power conversion efficiency (PCE) of blade‐coated photovoltaics. In this work, ethylene glycol (EG) is introduced as an inert co‐solvent in perovskite precursor solutions to achieve high‐quality perovskite films via blade coating. The high viscosity of EG facilitates the deposition of thick perovskite films ranging from 400 to 2000 nm, while its low vapor pressure effectively suppresses premature nucleation before vacuum flashing, leading to films with enhanced morphology. As a result, the blade‐coated PSCs achieve an impressive champion PCE of 24.10% and retain 89% of their initial efficiency after 600 h of continuous operation.