Effects of Alkoxy Side Chains on the Electrical and Thermoelectric Properties of Poly(3‐pentyloxythiophene)

Abstract Poly(3‐pentyloxythiophene) (P3PT), a polythiophene derivative bearing an alkoxy side chain, was synthesized, and the effects of side chain engineering on its electrical and thermoelectric properties were studied. The polymer has good solubility, which allowed its structure to be analyzed and its molecular weight to be determined. Electrochemical and optical analyses revealed that P3PT has a lower oxidation potential and its absorption is redshifted relative to that of poly(3‐hexylthiophene) (P3HT), indicating that the side‐chain has an electron‐donating effect and extends the π‐conjugation. In situ conductivity measurements—conducted while using an electrochemical method to precisely control the doping level—enabled the intrinsic charge transport properties to be evaluated. The thermoelectric performance of freestanding films of P3PT was also investigated and compared with that of P3HT. This comprehensive study provides valuable insights into the influence of alkoxy substitution on the electronic structure, doping behavior, and potential applications of polythiophene‐based materials.