Thermoelectric Properties of a Family of Benzodifuranone-Based Conjugated Copolymers in Oriented Thin Films Doped Sequentially With NDMBI-H

This study demonstrates the possibility to enhance thermoelectric properties of n-type benzodifuranone-based copolymers using a combination of polymer orientation (using high temperature rubbing) and sequential doping with the dopant N-DMBI-H. It focuses on the impact of the side chain length and the chemical nature of the comonomer (thiophene vs furan) on the efficacy of this methodology that preserves the facile solution-processability of this polymer family and enables effective sequential doping without a thermal activation step. The combination of high temperature rubbing and thermal annealing helps reach a high orientation of the copolymers with the thiophene comonomer regardless of the length of the side chains whereas the furan-based polymer is marginally aligned. The high orientation of thiophene-based copolymers results in a strong improvement of electrical conductivity and power factors reaching up to 9.8 ± 1.6 S cm⁻¹ and 8 ± 3 µW m^−1.K², respectively.