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Preparation and Characterization of Conducting Polymer Nanomaterials

Author: YangYaJie
Tutor: JiangYaDong
School: University of Electronic Science and Technology
Course: Materials Physics and Chemistry
Keywords: Nanostructured materials PEDOT Conductive polymer Reverse micelles Gas sensors LB films
CLC: TM24
Type: PhD thesis
Year: 2007
Downloads: 1110
Quote: 9
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Abstract

In recent years, the conductive polymer nanostructures become a hot research has excellent light, electricity, gas sensing performance. This thesis novel conductive polymer poly (3,4 - ethylene dioxy thiophene) (PEDOT) as the main material, starting from the materials synthesis, using a different method of preparation of different forms of the PEDOT nano structure, and using a variety of methods for preparing the the nanostructure characterization, depth study of the PEDOT light, electricity, gas sensitivity characteristics of the nanostructure, and further applied to the nano structure of the conductive polymer in the organic electronic device, improve the performance of the device. Its main contents are summarized as follows: 1. Polymerization and doping simultaneously reverse micellar system prepared dispersed small particle size PEDOT nanoparticles and UV - visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR ), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM) analysis, the nanoparticles were characterized. The experimental results showed that the amount of oxidant, sonication, the polymerization temperature and doping level have different degrees of influence on the morphology of the PEDOT nanoparticles, electrical properties, and gas sensitivity performance in the polymerization process; the PEDOT nanoparticles methylbenzenesulfonate effectively doped heteroaryl, when the dopant concentration is about 0.17 M, the PEDOT chain orientation most rules, at 6.7 °, 12.7 ° and 25 ° diffraction peak appears; thermogravimetric method (TG) analysis showed good thermal stability of PEDOT nanoparticles in ordinary block material, the dopant concentration on the thermal stability of the nano-particles have a certain extent affected, which is a dopant affecting the orientation of the molecular chains and result in change of the thermal stability of the nano-particles; PEDOT nanoparticles HCl gas for the first time sensitivity deposited nanoparticles QCM device response time of 20 ppm gas 20 S, and has a good response and recovery characteristics, and can effectively detect lower concentrations (5 ppm) of HCl gas, gas sensing properties superior to conventional PEDOT particles. This is due to the nano-particles have a larger surface area for the gas molecules to provide a better adsorption and desorption conditions. 2 by the polymerization of the monomers - solution infiltration - polymeric tube method performed at the same time in the porous alumina (AAO) template prepared PEDOT nanotubes. Morphology analysis showed that the synthesis of the PEDOT nanotube diameter of 400 ~ 500 nm, copy the shape and size of the pores of the template, to adjust the aperture size and pore shape of the PEDOT nanotubes shape; inferred PEDOT nanotube growth in a bore includes two processes: the first is the infiltration of the polymer solution throughout the tunnel. Secondly, the cation radical generated in the polymerization process and the PEDOT doped state due to the positive charge generated in the cell walls \show that the adsorption after the adsorption of the polymer and the polymerization of the monomers in the template wall result in different molecular chains are arranged so that PEDOT nanotubes orderly molecular arrangement affected; method using the four-point probe and the scanning tunneling microscope (STM) of the nano tube electrical properties, found single PEDOT nanotubes conductivity than wafer value from 5.5 S / cm to 17.6 S / cm change, this may be due to the suppression of the large contact resistance between the into blocks Hou Nami tube cause wafer resistor The larger: Gas Sensitivity testing found that the nanotubes have a different sensitivity to a variety of volatile organic gases can, particularly volatile alcohols, such as methanol, ethanol, showed much better sensitivity than the ordinary block material. The test results show that PEDOT nanotubes 1000 ppm methanol gas, the response time of approximately 10 to 20 S test repeatability than 15 times, indicating PEDOT nanotubes not only provides a greater surface area for gas molecules adsorbed, and the tube in the molecular chain orientation consistent, to reflect better sensitivity can. 3 using LB induced deposition method to prepare the different layers of the poly (3,4 - ethylene dioxy thiophene) / polystyrene sulfonic acid (PEDOT-PSS) conductive composite film. Octadecylamine (ODA) for the first time and octadecylamine / stearic acid (SA) ionized monolayers PEDOT-PSS nano particles subfacies and the ODA / PEDOT-PSS assembly into pure water subphase film behavior. The experimental results found PEDOT-PSS nanoparticles monomolecular film having wrapped, forming a stable complex with a single-molecule film ODA and SA molar ratio of 2:1, the a the subfacies temperature 23 ° C, the PEDOT-PSS, a concentration of 1 × 10 ^{-3 M, the lamination rate of 5 mm / min, the film pulling rate of 1 mm / min under the conditions of the film has good film-forming properties; secondary ion mass spectrometry (SIMS) and small-angle X-ray reflectivity (XRR ODA / PEDOT-PSS assembled body formed of a multilayer composite film has a good layered structure and single-layer thickness of approximately 23 nm) analysis showed that, with the size of the nanoparticles considerable; design different test structures, the measurement of the composite vertical conductivity of the film and the level of conductivity, studied film dc current - voltage characteristics and results of fitting the model with variable range hopping (VRH), results showed that the three-dimensional variable range hopping (3D-VRH) model can better explain the multilayer film in the migration of the carrier; LB film to the PEDOT-PSS as a hole buffer layer of the OLED device was prepared for the first time found that the LB film to improve the injection efficiency of the carrier of the device, but further studies showed that the structural stability of the film has to be raised. 4 a first time using modified LB film method, eicosanoic acid (AA) LB film as the template, was prepared by reacting 3,4 - ethylene dioxythiophene (EDOT) monomers polymerized in the LB film between the hydrophilic groups, AA / PEDOT composite LB film. UV-Vis, FT-IR and XPS analysis indicated that the EDOT effective polymerization, in the multilayer film generated PEDOT conductive polymer; XRR and SIMS analysis indicates that the film has a good layered ordered structure, further study found EDOT in AA the polymerization layer film destroyed the orderliness of the original LB film, the layered structure may be provided with the polymerization process to produce the destructive effects of: the four-point probe and the semiconductor tester study the performance of the thin-film conductive found that AA / PEDOT The conductivity of the multilayer film with the treatment time variation to produce mutant, which is associated with the conductive channel of the multilayer film \The test results also show that the AA / PEDOT film superior conductive PEDOT spin coating film and ODA-SA/PEDOT-PSS-composite film, which is due to higher the PEDOT Conjugate prepared in situ, and the film has a good layered The orderly structure; vertical tensioned membrane in the interdigital electrodes prepared by different layers of AA / PEDOT film, measuring the sensitivity of the film on HCl gas can. The results show that the film thickness, process temperature, pull the film membrane pressure can have varying degrees of impact of AA / PEDOT composite LB film gas sensitivity. Found in the concentration range of the smaller gas (20 to 60 ppm), the AA / PEDOT multilayer ordered film to gases exhibit a nonlinear response characteristic and show a linear response characteristics, while at a higher concentration range, and its sensitive mechanism could be interpreted as The electrons in the PEDOT conjugated system and the oxidizing gas transfer; HCl gas dynamic processes in the AA / PEDOT composite LB films including gas diffusion and adsorption, diffusion theory and with adsorption theory of this process .}

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