Brush and Dry: A Posttreatment-Free Simple Process to Pattern PEDOT:PSS Films with Enhanced Thermoelectric Performance via Shear Flow-Induced Morphology Tuning

Brush printing is a promising meniscus-guided technique to facilitate the transition from optimized organic thermoelectric materials to functional printed thermoelectric generators (TEGs) due to its dual advantage: (1) precise control of solvent evaporation to tune film morphology for enhanced charge transport and (2) patterning capabilities. This study systematically investigates the relationship between brush-induced morphology and thermoelectric performance in PEDOT:PSS films. We observed molecular chain extension, anisotropic alignment, and improved crystalline packing under optimal brushing conditions. This optimized morphology led to a 3-fold increase in electrical conductivity, up to 1900 S cm-1, and a high power factor of 170 μW m-1 K-2, without any wet posttreatment steps. This work demonstrates that brush printing offers a simple and scalable process route for organic thermoelectrics, effectively bridging the gap between high-performance materials and their practical applications in TEGs.