Solvent‐Mediated n‐Type Doping of SWCNTs to Achieve Superior Thermoelectric Power Factor

Abstract Carbon nanotubes (CNTs) have been demonstrated as promising candidates for thermoelectrics (TEs) owing to their excellent electrical and mechanical properties. Here a new dopant to obtain flexible n‐type CNT‐based TE films from solution is reported. By doping single‐walled carbon nanotubes (SWCNTs) with tetrabutylammonium bromide (TBAB), p‐type nanotubes can be successfully converted to n‐type form, which is confirmed by both Raman and X‐ray photoemission spectroscopy (XPS) spectra. Furthermore, the influences of doping concentration and dispersion medium on TE properties are investigated. The optimal n‐type SWCNT films fabricated in N,N‐dimethylformamide (DMF) solvent exhibit an impressive power factor of 339 µW m⁻¹ K⁻² and excellent air stability by less than 10% variation of Seebeck coefficient during 192 h at room temperature without encapsulation, both of which are among the hitherto highest reported. This work sheds light on the interaction between TBAB molecules and SWCNTs in different dispersion media and offers a guideline for efficient n‐doping of SWCNT based TE materials.