Backbone Effects on the Thermoelectric Properties of Ultra-Small Bandgap Conjugated Polymers

Dexun Xie; Jing Xiao; Quanwei Li; Tongchao Liu; Jinjia Xu; Guang Shao

doi:10.3390/polym13152486

Backbone Effects on the Thermoelectric Properties of Ultra-Small Bandgap Conjugated Polymers

Polymers (Basel). 2021 Jul 28;13(15):2486. doi: 10.3390/polym13152486.

Authors

Dexun Xie^{1

2}, Jing Xiao^{1

2}, Quanwei Li^{1

2}, Tongchao Liu³, Jinjia Xu⁴, Guang Shao^{1

2}

Affiliations

¹ School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China.
² Shenzhen Research Institute, Sun Yat-sen University, Shenzhen 518057, China.
³ Shenzhen Key Laboratory of Polymer Science and Technology, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China.
⁴ Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47906, USA.

Abstract

Conjugated polymers with narrower bandgaps usually induce higher carrier mobility, which is vital for the improved thermoelectric performance of polymeric materials. Herein, two indacenodithiophene (IDT) based donor-acceptor (D-A) conjugated polymers (PIDT-BBT and PIDTT-BBT) were designed and synthesized, both of which exhibited low-bandgaps. PIDTT-BBT showed a more planar backbone and carrier mobility that was two orders of magnitude higher (2.74 × 10^-2 cm²V^-1s^-1) than that of PIDT-BBT (4.52 × 10^-4 cm²V^-1s^-1). Both exhibited excellent thermoelectric performance after doping with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, where PIDTT-BBT exhibited a larger conductivity (0.181 S cm^-1) and a higher power factor (1.861 μW m^-1 K^-2) due to its higher carrier mobility. The maximum power factor of PIDTT-BBT reached 4.04 μW m^-1 K^-2 at 382 K. It is believed that conjugated polymers with a low bandgap are promising in the field of organic thermoelectric materials.

Keywords: carrier mobility; conjugated polymers; organic thermoelectric materials; ultra-small bandgap.

Abstract

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