Scalable manufacturing of roll‐to‐roll slot‐die coated perovskite solar cells

Perovskite solar cells (PSCs) have recently demonstrated laboratory-scale power conversion efficiencies (PCEs) exceeding 27%, a value that now matches the most efficient silicon photovoltaics. Their low-temperature, solution-processable fabrication and compatibility with flexible substrates position PSCs as candidates for next-generation photovoltaic technologies. Notably, PSCs fabricated on flexible substrates have been shown to demonstrate efficiencies that exceed 26% PCE, however the efficiency of flexible modules remains under 22%. Roll-to-roll (R2R) deposition has emerged as a leading candidate to transition PSC fabrication to a practical manufacturing environment. In this review, we focus on R2R processing of PSCs and discuss the techniques that have been developed to control perovskite structure, crystallinity, and morphology. In particular, we explore the effects of perovskite composition, solvent engineering, film-drying, and additive engineering, which can be harnessed to optimise device performance, with fully R2R-fabricated PSCs demonstrated having PCEs above 15%, and R2R printed modules reaching a PCE of 11%. A number of challenges remain, including maintaining film quality at high substrate throughput, ensuring the long-term stability of devices, and reducing the cost of module integration.