Spatially Regulated Gas Flow Control for Batch‐Drying of Large Area Slot‐Die‐Coated Perovskite Thin Films

Abstract Innovations in scalable fabrication processes are pivotal for transferring record power conversion efficiencies (PCEs) of spin‐coated perovskite/silicon‐based tandem solar cells (TSCs) from the laboratory scale to full‐size photovoltaics. In this regard, the homogeneous large‐area drying of precursor ink wet films poses one of the major hurdles. Gas‐assisted drying by linear high‐pressure slot jets comes along with an inhomogeneous flow field, causing unwanted backflows, non‐uniform drying patterns, and strong inhomogeneities at the sample edges. In response, it is demonstrated i) a new 2D comb‐nozzle (CN) drying technique that improves the homogeneity of drying processes and, ii) an adjusted strategy to fabricate high‐quality 2‐step slot‐die (SD)‐coated triple‐halide perovskite thin films. Remarkably, homogeneous and pinhole‐free large‐area SD‐coated perovskite SCs fabricated is demonstrated with all scalable techniques reaching up to 19.6% with enhanced mean PCE‐yields of 90% (compared to 62% with slot‐jet drying). Consequently, the CN drying method is employed for a material composition suitable for tandem applications ( E g ≈1.68 eV). Particularly, the reproducible fabrication of TSCs with PCEs up to 24.6% on large areas with homogeneous PCE variances of ±0.7% abs imply high homogeneity during the coating and drying process and confirms the importance of systematically controlled drying within an optimized 2‐step process.