Doped thieno[3,4-b]thiophene-based copolymers for p-type organic thermoelectric materials

Abstract

In this work, two conjugated polymers named PTbTTVT and PTbTTVT-F were obtained by TbT (thieno[3,4-b]thiophene) derivatives and linker TVT (1,2-bis(3-tetradecylthiophen-2-yl)ethene) copolymerization. PTbTTVT showed good orientation and better charge mobility, while the introduction of fluorine results in a disordered stacking and inferior hole mobility of PTbTTVT-F. Through the detailed study of the thermoelectric performance of polymers, we found that they both exhibited good performance with the best power factor (PF) of over 35 μW m⁻¹ K⁻². Although PTbTTVT-F showed much worse hole mobility compared with PTbTTVT, it could gain similar or superior PF when the suitable dopants were selected. The results implied that polymers with less ordered stacking could have more tolerance for the disruption of the dopant, and exploiting amorphous materials with prominent mobility might be a useful strategy to gain high performance organic thermoelectric materials (OTEs).