Decoupling phonon and carrier scattering at carbon nanotube/Bi2Te3 interfaces for improved thermoelectric performance

Inorganic semiconductor-carbon nanotube (CNT) hybrid is a new type of promising flexible thermoelectric (TE) material for efficient thermal energy recovery and positive cooling. However, the influence of CNTs, that typically have a high thermal conductivity (kappa), high electrical conductivity (sigma) and low figure-of-merit (ZT) value, on the hybrid properties remains unclear, and this is vital for the rational design of high-performance CNT-containing TEs. Here, we report a flexible TE material of Bi2Te3 nano-crystals attached to a CNT network with tuned k and s. By plasma pretreating the CNT scaffold, a high density of defects was generated at the hybrid interface, which introduced strong phonon scattering without much sacrifice of s, due to the different attenuations of the wavelength spectra of phonons and carriers. Consequently, the hybrid lattice kappa was significantly reduced to similar to 0.19 W m(-1) K-1, and a ZT value of similar to 0.25 was obtained at room temperature, similar to 50% higher than that obtained using pristine CNTs. Our results provide a general approach to the decoupling of phonon and carrier transport properties by tailoring the hybrid interface, which is significant for developing high-performance flexible CNT-based TE hybrids. (C) 2020 Elsevier Ltd. All rights reserved.