Thermoelectric properties of a vertically aligned carbon nanotube array with embedded bismuth telluride

Abstract

Recently, thermoelectric (TE) devices have attracted much attention because they have no moving parts, simple structures, high reliability, and environmental friendly, when compared to other green energy techniques. In this paper, we report a novel thermoelectric composite constructed one with a self-assembled highly oriented Sb doped Bi2Te3 and one without doping nanoflake layer deposited on regular vertically aligned checkerboard-patterned multi-walled carbon nanotube (MWCNT) arrays (500 nm squares and 1 µm pitch) on insulated SiO2/Si substrates. The height of Bi2Te3/Bi0.4Sb1.6Te3, MWCNTs and volumetric ratio of MWCNT to Bi2Te3/ Bi0.4Sb1.6Te3 are about 3 μm, 1.5 μm, and 25%, respectively. The blending of regular vertically aligned MWCNT patterns into Bi0.4Sb1.6Te3 results in a dramatically enhancement of Seebeck coefficient and electrical conductivity. The Seebeck coefficient and power factor of Bi0.4Sb1.6Te3-MWCNTs show a maximum value of 600 μV/K and 60 μW/cm-K2 at 160 K and gradually decrease to 409 μV/K, and about 14.1 μW/cm-K2 at 300 K, respectively. The significant records of the low temperature Seebeck coefficients and relative electrical properties are extremely important for the fundamental understanding of vertically aligned MWCNT embedded thermoelectric composites.