Charge and thermoelectric transport mechanism in donor-acceptor copolymer films

Abstract

Wearable thermoelectric conversion devices are one of the key technologies for future sustainable society, and flexible conducting polymer films are strong candidates for these applications. However, the thermoelectric transport mechanism of these materials is still unclear due to their unique disordered nature, in particular the poor interconnectivity between crystalline domains. Here, to overcome this limit, donor-acceptor (D-A) copolymer films are selected because of the efficient connection between domains via rigid tie molecules. We investigated their thermoelectric and carrier transport properties using the electrolyte-gating technique and perfectly described both of them based on the two-dimensional variable range hopping model with a linear density of states around the Fermi level energy. The present results provide a fundamental understanding of the thermoelectric physics in D-A copolymer films towards application in wearable devices.