Tailoring Wetting Properties of Organic Hole-Transport Interlayers for Slot-Die-Coated Perovskite Solar Modules

Abstract

The strategy of incorporating self-assembled monolayers (SAMs) with anchoring groups is an effective and promising method for interface engineering in perovskite solar cells with metal oxide charge-transporting layers. However, coating SAM layers in upscaled perovskite solar modules (PSMs) using slot-die coating is challenging due to the low viscosity and wettability of the solutions. In this study, a triphenylamine-based polymer poly([{5-[4-(diphenylamino)phenyl]-2-thienyl}(4-fluorophenyl)methylene]malononitrile) (pTPA)–TDP, blended with SAM based on 5-[4-[4-(diphenylamino)phenyl]thiophene-2-carboxylic acid, is integrated to address these challenges. And, p–i–n-oriented PSMs on 50 × 50 mm² substrates (12 sub-cells) are fabricated with a NiO hole-transport layer and organic interlayers for surface modification. Wetting angle mapping shows that ununiform regions of the slot-die-coated SAM has extreme hydrophobicity, causing absorber thickness fluctuations and macro-defects at buried interfaces. The blended interlayer at the NiO/perovskite junction homogenizes surface wettability and mitigates lattice strain, enabling the effective use of SAM properties on large surfaces. This improved energy level alignment, enhancing the power conversion efficiency of the modules from 13.98% to 15.83% and stability (ISOS-L-2, T₈₀ period) from 500 to 1630 h. In these results, the complex effects of using SAM in slot-die-coating technology for large-scale perovskite photovoltaics are highlighted.