Brush-Printed Thermoelectric Generators

Organic thermoelectric materials (OTEs) present distinct advantages such as cost-effectiveness, large-area processing capabilities, material abundance, and flexibility. However, their widespread adoption is limited by inherent performance constraints. While research has largely concentrated on novel materials and doping strategies, molecular ordering—a proven technique for enhancing organic transistor performance—remains underexplored in OTEs.<br/><br/>Our objective is to establish a versatile approach for enhancing the performance of thin-film OTEs by inducing anisotropic molecular conformation changes and increasing crystallinity through brush printing. We developed a protocol for the well-known P-type polymer PEDOT and systematically studied the effects of coating speed and film thickness. We hypothesize that the directional capillarity effect induced by the brush bristles will promote the elongation and connectivity of PEDOT-rich domains. Anisotropic performance is expected at the mixed regime of coating, which can lock in place the aligned polymer chains while maintaining relatively high crystallinity.<br/><br/>The induced nanoscale morphological changes significantly enhanced the conductivity along the printing direction without compromising the Seebeck coefficient, resulting in a 270% improvement in power factor compared to similar spin-coated samples. We will apply a similar protocol to less-explored emerging N-type polymers, thereby introducing a novel method to produce high-performance OTE generators that encompass both P-type and N-type conducting polymers.