Ambient-air fabrication of perovskite solar cells: Challenges, progress, and perspectives

Perovskite solar cells (PSCs) have emerged as a revolutionary photovoltaic technology due to their exceptional optoelectronic properties and low-cost solution processability, yet their fabrication typically demands stringent inert conditions to mitigate environmental degradation. However, achieving efficient and stable PSC fabrication in ambient air is crucial for their widespread commercialization, as it significantly reduces manufacturing costs, simplifies process flow, and enables scalable roll-to-roll and printing techniques. The main challenges hindering ambient processing include moisture-induced degradation, oxygen-related oxidation, and humidity-driven variations in crystallization kinetics, which often lead to reduced film quality, defective interfaces, and limited device performance. Recent advancements in ambient-air processing of PSCs present a promising pathway toward scalable and eco-friendly manufacturing, though challenges such as moisture sensitivity, oxygen-induced degradation, and crystallization control remain. This review examines ambient-air effects on perovskite formation, device performance, and stability, alongside strategies for improvement via compositional engineering, solvent optimization, and novel deposition methods. Furthermore, we discuss the progress in lab-scale and large-scale ambient-air fabrication methods, emphasizing their potential for industrial translation. Finally, we outline future research directions to enhance the efficiency, stability, and commercial viability of air-processed PSCs, underscoring their critical role in sustainable energy development.