Reparation And Thermoelectric Performance Of Poly(3,4-ethylenedioxythiophene) Micro-Nanostructure And Its Nonocomposites

Thermoelectric materials, as a green energy material, can realize the direct conversion between heat energy and electrical energy. To date, most of the excellent thermoelectric materials are inorganic materials. Nevertheless, various factors such as the difficulty of processing, expensiveness of their raw materials, and the toxicity of elements seriously limit their practical applications. Being a class of promising thermoelectric materials,conducting polymer materials have obvious advantages.Due to its simple structure, good stability and high conductivity, the conducting polymer of poly(3,4-ethylene dioxythiophene)(PEDOT), have been widely used in the organic thin film solar cell materials, antistatic coatings, electrochromic materials, plastic electronic components, transparent battery materials and sensors. This study is mainly concentrated on the preparation and thermoelectric performance of PEDOT micro-nanostructures and the corresponding nanocomposites. The main contents of this thesis are devided into three parts:1. Using ferric chloride as an oxidant, bulk and four micro-nanostructured PEDOT(spherical, rod, tube, fibre) samples were synthesized by reverse micelle polymerization method. By measuring their conductivities and Seebeck coefficients, it can be concluded that the power factor is closely connected with the morphology evolution of micro- nanostructure. The thermoelectric performance follow the order of bulk PEDOT without nanostructure < globular nanoparticles < nanorods < nanotubes < nanofibres. In order to shed light on the mechanism of PEDOT thermoelectric performance tuned by its nanostructure, various measurements, such as Hall effect tests, X-ray diffraction(XRD), X-ray photoelectron spectra(XPS) and Fourier transform infrared(FTIR) spectra, were conducted.2. By using chemical oxidation method in reverse micelles,two different structured PEDOT / SWCNT composites were prepared in two different solvents(xylene and hexane), respectively. The composites using xylene as the solvent have a coral-like structure, while the composites using hexane as the solvent display a cable-like morphology with smooth surface. The thermoelectric property of the composites used xylene as the solvent are greatly higher than that of the composites using hexane as a solvent. At the same time, the relationship of their structures and performance was studied by XRD、Raman spectra and XPS.3. Using chemical oxidation method in aqueous micelles,the PEDOT / SWCNT composites with nonuniform coating were prepared. Thermoelectric performances were enhanced significantly with the increase of carbon tube loading. it may be described as the special“reinforced concrete”structure for the composites, which could facilitate the transport of electrons. The present findings may be expanded to other conducting polymers with thermoelectric function, providing a new way to fabricate novel polymer thermoelectric materials.