Self-assembled monolayers (SAMs) based on carbazole-anchored molecules such as Me-4PACz have emerged as highly effective hole-selective contacts for high-performance perovskite solar cells (PSCs). However, the widespread use of SAMs in PSCs manufacturing has so far been limited to their conventional deposition through spin coating, which is incompatible with high-throughput and continuous fabrication. In this work, we present a comprehensive optimization, systematic analysis, and upscaling demonstration of slot-die coated (SDC) SAMs, establishing an industrially relevant pathway for large-area SAM deposition in perovskite photovoltaics.

Optimization of the slot-die coating process, including substrate to coating head gap, coating speed, and SAM solution concentration, enabled the formation of highly uniform and well-packed SAM layers. These optimized films resulted an improvement in power conversion efficiency (PCE) of SDC SAM based PSCs compared to spin-coated (SC) SAM counterparts, with the champion SDC SAM based device showing a PCE of 24.89%. The performance enhancement in SDC SAM based devices is primarily attributed to a significant rise in open-circuit voltage, indicating reduced nonradiative recombination at the SAM/perovskite interface.

A series of optoelectronic and interfacial characterizations such as impedance spectroscopy, contact-angle measurements, Kelvin probe force microscopy, surface photovoltage measurements, and morphology studies, revealed that SDC SAM layers provide superior surface coverage, improved wettability toward perovskite inks, and an increase in work function. These characteristics contribute to more efficient hole extraction and reduced interfacial recombination without altering the bulk crystallographic properties of the perovskite layer.

The upscaling capability of this method was demonstrated through uniform deposition on 150 mm × 150 mm patterned ITO substrates, yielding 36 small-area devices with excellent spatial uniformity and an average PCE of 20.6%. Furthermore, mini-modules with active area 8 cm² comprising five series-connected sub-cells achieved PCEs exceeding 22%, confirming the process compatibility with module-scale fabrication. The maximum power point tracking over a period of 450 hours showed high operational stability while retaining 95% of initial PCE in SDC SAM based devices

Overall, this study establishes slot-die coating of SAMs as a scalable, robust, and reproducible approach, offering a critical pathway toward industrial manufacturing of highly efficient and scalable perovskite photovoltaic devices.