Solution-Processable Conjugated Polymer/SWCNT Composites with Balanced p-Type and n-Type Properties for Scalable Thermoelectric Modules via Automated Dispensing

Abstract

Thermoelectric (TE) materials capable of converting waste heat into electrical energy represent a promising solution for sustainable energy harvesting. This study demonstrates scalable TE modules through automated 3D dispensing, utilizing solution-processable conjugated polymer/single-walled carbon nanotube (SWCNT) composites as complementary p-type and n-type components. The p-type polymer integrated with SWCNTs (50:50 weight ratio), achieving an electrical conductivity of 478 ± 13 S cm⁻¹, while the n-type polymer with SWCNT (40:60 weight ratio), exhibited enhanced environmental stability with electrical conductivity of 202 ± 19 S cm⁻¹. The optimized p-type and n-type composites achieve power factors of 47 ± 8 and 64 ± 1.5 µW m⁻¹ K⁻², respectively, with corresponding figure of merit (ZT) values of 0.11± 0.02 and 0.15 ± 0.02 at 303 K. A three pair TE module generates a maximum power output of 0.18 µW at ΔT = 100 K. Temperature-dependent measurements reveal distinct transport mechanisms: weak metallic behavior in the p-type composite and thermally activated hopping (E_a = 22.4 meV) in the n-type film. The successful integration through automated fabrication demonstrates potential for scalable production of flexible organic TE modules.