High-Performance Perovskite Solar Cells and Modules via Slot-Die Coating: Engineering Advances, Photoluminescence Insights, and Future Perspectives

Slot-die coating has solidified its role as the preeminent industrial-scale deposition technique for perovskite photovoltaics, combining exceptional material utilization, direct compatibility with roll-to-roll production, and high-throughput capability. This review comprehensively surveys recent advances in slot-die-coated perovskite solar cells and modules, with a focused analysis on the governing principles behind the structure-property-performance relationship. We first deconstruct how coating methodologies-including one-step, two-step, and hybrid processes-dictate film morphology and crystalline quality. We then elaborate on perovskite ink engineering, emphasizing the critical role played by solvent selection and functional additives in controlling nucleation kinetics and crystal growth during large-area deposition. Furthermore, we examine innovative interface modulation strategies that enhance film integrity, suppress defects, and mitigate ion migration. A key distinctive feature of this review is its emphasis on advanced photoluminescence (PL) characterization techniques-such as in situ PL, PL imaging, and time-resolved PL-which provide unparalleled insights into crystallization pathways, defect distribution, and charge carrier dynamics. These tools are indispensable for mechanistic decoding and rational optimization of the slot-die process. Finally, we outline pressing research directions, highlighting the necessity to overcome persistent challenges in operational stability, efficiency-stability trade-offs, the establishment of unified stability assessment protocols, and manufacturing reproducibility to ultimately bridge the laboratory-to-fab gap and accelerate the commercialization of slot-die-coated perovskite solar modules.