Synergistic Impacts of Electrolyte Adsorption on the Thermoelectric Properties of Single‐Walled Carbon Nanotubes

Single‐walled carbon nanotubes are promising candidates for light‐weight and flexible energy materials. Recently, the thermoelectric properties of single‐walled carbon nanotubes have been dramatically improved by ionic liquid addition; however, controlling factors remain unsolved. Here the thermoelectric properties of single‐walled carbon nanotubes enhanced by electrolytes are investigated. Complementary characterization with absorption, Raman, and X‐ray photoelectron spectroscopy reveals that shallow hole doping plays a partial role in the enhanced electrical conductivity. The molecular factors controlling the thermoelectric properties of carbon nanotubes are systematically investigated in terms of the ionic functionalities of ionic liquids. It is revealed that appropriate ionic liquids show a synergistic enhancement in conductivity and the Seebeck coefficient. The discovery of significantly precise doping enables the generation of thermoelectric power factor exceeding 460 µW m–1 K–2. The soft ionic functionalities of electrolytes are utilized in order to dramatically enhance thermoelectric transport in single‐walled carbon nanotube films. The composite of electrolytes and nanotubes exhibits a power factor of ≈0.5 mW m–1 K−2. The hole doping leading to enhanced thermoelectric properties is discussed on the basis of supramolecular interactions and named supramolecular doping.