Energy harvesting and temperature sensing thermoelectric devices based on the carbon template method

A series of self-supporting carbon nanomaterial films with different morphologies were employed as conductive templates for n-junction after polyethyleneimine (PEI) doping by taking advantages of the entanglement between carbon nanotubes. With the assistance of dimethyl sulfoxide (DMSO)-treated poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) films as p-junction, flexible and light-weight thermoelectric generators (TEGs) were assembled. The effect of the morphology of the carbon nanomaterial, including multi-walled carbon nanotube (MWCNT), whisker carbon nanotube (WSCNT), and graphene on the electrical conductivity, mechanical properties and morphology of n-junction was investigated, on basis of which thermoelectric properties of TEG were evaluated. The properties of the three carbon-based self-supporting films show significant differences. The MWCNT/PEI film exhibits a tensile strength of up to 36.23 +/- 0.57 MPa due to the high entanglement network density of MWCNT. The entanglement of WSCNT/MWCNT/PEI provides an ideal conductive template for PEI to prepare n-junction material. TEGs with PEDOT:PSS-DMSO and WSCNT/MWCNT/PEI as p- and n-junctions show high power generation performance and cyclability. The output power density is up to 4.6 nW/cm(2) at Delta T = 42.0 K, matched to a suitable load. With its fast response and slow recovery, this TEG is expected to be used for human health monitoring and energy storage.