Ambient Processing of Large‐Area and Fully Slot‐Die‐Coated MAPbI ₃ Perovskite Solar Cells

The performance of perovskite solar cells (PSCs) has increased markedly from 17.9% to 26.95% in less than a decade, rendering this technology increasingly competitive in the photovoltaic field. Among scalable deposition methods, the slot‐die coating technique stands out for its suitability in large‐area film deposition, offering perovskite film uniformity, reduced material waste, enhanced reproducibility, and compatibility with flexible substrates. This study focuses on optimizing slot‐die coating parameters for all active layers in inverted PSCs, namely the hole transport layer, perovskite absorber, and electron transport layer. The selected device architecture, PTAA/MAPbI ₃ /PCBM/BCP/Ag, is recognized for its superior air stability. The film morphology was analyzed using scanning electron microscopy and atomic force microscopy, while the crystallinity of the perovskite layer was assessed through X‐ray diffraction. The fabrication process for a 5 cm ² PSC device was refined using a design of experiments methodology. The champion cell, manufactured using slot‐die coating in ambient air conditions, reached a power conversion efficiency of 8.12% and maintained stable performance for over 800 h when stored in the dark under an inert atmosphere.