Wasted heat, which is mainly produced during industrial manufacturing and fuel combustion, is a neglected but enormous energy source. Application of thermoelectric material and generator could be suitable way for heat recycling, since it provides direct conversion from heat into electricity. Recently, conjugated polymer receives great interests in thermoelectric applications because the π-π stacking structure facilitates the charge transport and also improve the charge carrier density. As a result, the electrical conductivity could be greatly improved. However, the thermoelectric figure-of-merit of polymer is still low compared to inorganic material because the charge transport efficiency of current state-of-art polymer reaches a bottleneck.<br/>Here, we develop a novel two-dimension (2D) polythiophene. In this polythiophene, multi-thiophene ring is distributed in both main chain and side chain which is called “2D” structure. Because of existence of large density of π-π stacking structure, the π-π distance and polymer crystal plane are largely reduced and further facilitate charge transport. As a result, the electrical conductivity is 100 times larger than that of corresponding 1D conjugated polymer and the thermoelectric figure-of-merit is 20-fold. By using the 2D conjugated polymer as matrix, additional fillers, such as quantum dots, carbon nanotubes (CNTs), and organic-metal framework are introduced to further optimize the electrical conductivity and Seebeck coefficient through quantum confinement effect, polymer-CNTs junction and energy filtering effect respectively. Our study shows that the 2D conjugated polymer composites exhibit outstanding thermoelectric figure-of-merit in current state-of-art organic thermoelectric materials and indicates that the 2D conjugated structure could be employed into polymer matrix for future thermoelectric applications.

Two-dimensional polythiophene composites for thermoelectric applications

2019 Fall National Meeting

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