Thermoelectric properties of composite films prepared with benzodithiophene derivatives and carbon nanotubes

Benzodithiophene (BDT)-based conjugated polymers have garnered considerable interest due to their planar backbones and improved carrier mobility, and have found wide application in organic field-effect transistors and organic photovoltaics. However, there are few reports on the use of these conjugated polymers as thermoelectric materials. In this work, the conjugated polymer poly(benzo[1,2-b:4,5-b']dithiophene-alt-3,4-ethylenedioxythiophene) (PBDT-EDOT) was synthesized to investigate the thermoelectric behavior of its composite films with single-walled carbon nanotubes (SWCNTs). The polymer was characterized by 1H NMR, gel permeation chromatography, thermal gravimetric analysis and differential scanning calorimetry. The thermoelectric properties, carrier concentration and mobility of the composite films were also measured. It was found that the composite with an SWCNT content of 30% exhibited a high Seebeck coefficient of 82.1 μV K−1 at room temperature. Additionally, for composites with SWCNT contents below 90%, the power factors reached the highest values at the glass transition point of PBDT-EDOT in the temperature range of 300-400 K.