Low-hygroscopic solvents enable ambient blade coating of efficient perovskite solar cells

Scalable manufacturing of high-efficiency perovskite solar cells (PSCs) requires blade coating not only of the perovskite layer, but also of other functional layers, including organoammonium halide surface passivation layers and self-assembled monolayers (SAMs), under ambient conditions. However, organoammonium iodides and SAMs are highly hygroscopic and prone to hydrolysis and desorption, respectively, and they are commonly processed from hygroscopic alcohol. As a result, despite its importance for scalable production, ambient blade coating of these moisture-sensitive interfacial layers has rarely been demonstrated. Here, we report a general low-hygroscopic solvent system for blade coating hygroscopic organoammonium halides and SAMs. We mix alcohol with low-polarity alkane, where the alcohol dissolves the functional materials and the alkane suppresses moisture uptake during the blade-coating process under ambient conditions. Comprehensive chemical and optoelectronic characterizations confirm that low-hygroscopic solvent system is a general approach to blade coat both passivation layers and SAMs under high humidity. The devices with air blade-coated SAMs, perovskite, and passivation layers achieve a certified efficiency of 26.1% with negligible decrease even fabricated at 80% relative humidity. This work solves one of the most challenging issues of scalable fabrication of perovskite photovoltaics in ambient air.