Cosolvent Strategy in Blade-Coating Phenethylammonium Iodide Passivation Layers for Perovskite Solar Cells

Perovskite solar cells (PSCs) often suffer from defects due to rapid crystallization in solution-based fabrication. Surface passivation using phenethylammonium iodide (PEAI) can mitigate these defects, but traditional spin-coating methods limit their scalability. Blade-coating offers a cost-effective alternative, yet blade-coating PEAI passivation layers using isopropanol (IPA) based solution face the challenge of uneven coverage and perovskite degradation. Here, we introduce dibutyl alcohol (TBA) as cosolvent to enhance viscosity of the solution, forming a stable liquid column during blade-coating. This improves uniformity and reduces the level of IPA-induced corrosion. As a result, PSC efficiency increased from 21.6% to 23.0%, with an improved open circuit voltage from 1.14 to 1.17 V. The films also exhibited excellent moisture stability, maintaining performance for 3000 h at 24 °C and 50-60% RH. This study presents a scalable, sustainable passivation strategy for large-area perovskite films, advancing the industrial viability of PSCs.