Continuous carbon nanotube films for thermoelectric applications
File(s)
Author(s)
Zeng, Chongyang
Type
Thesis
Abstract
In this thesis, continuous carbon nanotube (CNT) films, fabricated by the floating catalyst chemical vapor deposition (FCCVD) method, have been explored as thermoelectric (TE) materials. Three different methods were studied to regulate the structure and configuration of CNT films and devices, aiming to achieve improved TE properties. Reduced thermal conductivity of CNT films was achieved by introducing defects on CNT films through mechanical stretching and heat-repairing CNT-based polycarbonate (PC) composites films. This defect engineering method achieved a 3.5-fold reduction in the thermal conductivity of CNT films, from 46 to 13 W m-1 K-1, without significantly affecting the Seebeck coefficient and electrical conductivity.
A new TE device architecture was also explored, inspired by the Kirigami art of cutting and folding, with built-in fins and self-folding capability. The device was suitable for both inorganic and organic TE materials. CNT films and Bi2Te3 worked as organic and inorganic TE materials in the device, showing a competitive power density/∆T2 of 19.95 nW mm-2 K-1 and 6.78 nW mm-2 K-1, respectively.
Finally, CNT films were optimised by dimethyl sulfoxide (DMSO) treated poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), with an electrical conductivity of 1589 S cm-1, 70% higher than the original one (933 S cm-1). Additionally, optimised CNT films showed better adhesion onto the electroded Kapton substrate and lower contact resistance, which translated into a better performing self-folded TEG with an open circuit voltage and output power of 93 mV and 85 µW at a ∆T of 80 K.
A new TE device architecture was also explored, inspired by the Kirigami art of cutting and folding, with built-in fins and self-folding capability. The device was suitable for both inorganic and organic TE materials. CNT films and Bi2Te3 worked as organic and inorganic TE materials in the device, showing a competitive power density/∆T2 of 19.95 nW mm-2 K-1 and 6.78 nW mm-2 K-1, respectively.
Finally, CNT films were optimised by dimethyl sulfoxide (DMSO) treated poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), with an electrical conductivity of 1589 S cm-1, 70% higher than the original one (933 S cm-1). Additionally, optimised CNT films showed better adhesion onto the electroded Kapton substrate and lower contact resistance, which translated into a better performing self-folded TEG with an open circuit voltage and output power of 93 mV and 85 µW at a ∆T of 80 K.
Version
Open Access
Date Issued
2024-07-29
Date Awarded
2024-11-01
Copyright Statement
Creative Commons Attribution NonCommercial Licence
License URL
Advisor
Bilotti, Emiliano
Publisher Department
Aeronautics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)