Enhanced Thermoelectric Properties of F4TCNQ Doped P3HT and Its Use as a Binder for Sb₂Te₃ Based Printed Thermoelectric Films

Flexible thermoelectric generators (FTEGs) are emerging energy harvesting devices that have generated recent research interest because of their scalability and low cost. The fabrication of FTEGs requires printing of thermoelectric elements on flexible substrates. The low thermal conductivity, solution processability, and low cost of polymers make them an attractive choice for flexible devices. A major challenge in their adoption is their very low electrical conductivity. The electrical conductivity of conjugated polymers can be improved by doping and addition of active particles. This article describes enhancements in the thermoelectric properties of poly(3-hexylthiophene) (P3HT) polymer using 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) as a dopant. The highest electrical conductivity obtained was 1.6 S/cm for 17 wt % dopant in the polymer. The highest Seebeck coefficient (102 μV/K) and power factor (1.6 μW/mK2) were also obtained for the same dopant concentration. As a result of using optimized wt % of F4TCNQ dopant in P3HT polymer, we improved the power factor of P3HT by an order of magnitude compared to the highest power factor for P3HT reported in the literature. This doped polymer was subsequently evaluated as a potential binding system for p-type Sb2Te3 active particles. The results for the P3HT-Sb2Te3 composite are compared against epoxy-Sb2Te3.