N-type organic thermoelectrics: demonstration of ZT > 0.3

Jian Liu*, Bas van der Zee, Riccardo Alessandri, Selim Sami, Jingjin Dong, Mohamad I. Nugraha, Alex J. Barker, Sylvia Rousseva, Li Qiu, Xinkai Qiu, Nathalie Klasen, Ryan C. Chiechi, Derya Baran, Mario Caironi, Thomas D. Anthopoulos, Giuseppe Portale, Remco W. A. Havenith, Siewert J. Marrink, Jan C. Hummelen, L. Jan Anton Koster*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

The ‘phonon-glass electron-crystal’ concept has triggered most of the progress that has been achieved in inorganic thermoelectrics in the past two decades. Organic thermoelectric materials, unlike their inorganic counterparts, exhibit molecular diversity, flexible mechanical properties and easy fabrication, and are mostly ‘phonon glasses’. However, the thermoelectric performances of these organic materials are largely limited by low molecular order and they are therefore far from being ‘electron crystals’. Here, we report a molecularly n-doped fullerene derivative with meticulous design of the side chain that approaches an organic ‘PGEC’ thermoelectric material. This thermoelectric material exhibits an excellent electrical conductivity of >10 S cm −1 and an ultralow thermal conductivity of <0.1 Wm −1K −1, leading to the best figure of merit ZT = 0.34 (at 120 °C) among all reported single-host n-type organic thermoelectric materials. The key factor to achieving the record performance is to use ‘arm-shaped’ double-triethylene-glycol-type side chains, which not only offer excellent doping efficiency (~60%) but also induce a disorder-to-order transition upon thermal annealing. This study illustrates the vast potential of organic semiconductors as thermoelectric materials.

Original languageEnglish
Article number5694
Number of pages9
JournalNature Communications
Volume11
Issue number1
DOIs
Publication statusPublished - 10-Nov-2020

Keywords

  • THERMAL-CONDUCTIVITY
  • NANOSTRUCTURED THERMOELECTRICS
  • ELECTRONIC-STRUCTURE
  • POLYMER
  • EFFICIENCY
  • MOBILITY
  • DESIGN
  • DOPANT
  • POWER
  • HEAT

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