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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/6156

    Title: 利用導電原子力顯微技術(CAFM)探討聚苯胺導電區域變化情形 --
    Authors: 張素珊;Su-Shan Chang
    Contributors: 化學研究所
    Keywords: 聚苯胺;導電原子力顯微鏡;Polyaniline;Conductive Atomic Force Microscope
    Date: 2005-06-27
    Issue Date: 2009-09-22 10:14:17 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 中文摘要 ??蝶丳敦w顯微技術是觀測奈米等級材料的重要技術,其中原子力顯微鏡及其衍生技術應用最廣,其量測方式為以探針在極接近樣品表面時,進行樣品表面掃瞄及局部物性量測。藉由導電原子力顯微鏡量測不同型態的聚苯胺膜在探針接觸且同時施加電壓下的表面型態、導電區域及導電特性。EB態與ES態之聚苯胺膜表面型態類似,但從HCl(aq)、HClO4(aq)中製備而得之聚苯胺膜為圓盤狀堆疊,而由H2SO4(aq)中製得為鏈狀堆積,但表面型態不受膜厚度及摻雜酸種類影響。由CAFM的數據得知所有聚苯胺膜的導電度都不均勻,整塊膜可視為導電(絕緣)島嶼散佈在絕緣(導電)海中且隨聚苯胺膜的摻雜度、厚度、與摻雜子的不同而變化:隨摻雜程度增加,其導電區域從孤立小島演變成密集分佈連結的島嶼,而I-V曲線也顯示其由半導體性質演變成具有金屬導電性質;隨厚度增加,導電區域數目增加,最後連結成大板塊,且I-V曲線也由半導體變成具類金屬的導電特性;在HClO4(aq)中製得之聚苯胺膜(<120 nm),分子鏈的共軛程度最短,因此用HCl、H2SO4、與HClO4摻雜後的導電度類似且皆為半導體,由H2SO4(aq)、與HCl(aq)聚合而得之聚苯胺薄膜分子鏈的共軛程度類似,且皆以HClO4摻雜後的導電度最高,並呈現金屬導體特性。 Abstract Scanning probe microscopies (SPMs) are important technologies providing the variety properties of material surfaces with nanometer-scale spatial resolution. Atomic Force Microscopy (AFM) was one of the most widely used techniques of the SPM. The surface morphology and the physical properties of the materials can be measured simultaneously by recording the various interactions as well as the atomic force between the sample and the tip. By applying a voltage between sample and a conductive AFM tip, a so-called Conducting Atomic Force Microscopy (C-AFM), topographic and current images were obtained simultaneously. Furthermore, a current-voltage trace can be recorded on a selected spot of the image, where one can study the electrical characteristics of the surface. The topographical images of emeraldine base (EB) are similar to emeraldine salt (ES). The globular-shaped structure was observed in polyaniline (PANI) films prepared from HCl and HClO4 aqueous solutions, whereas the entangled fiber-shaped structure is detected when PANI films were prepared in H2SO4(aq). The topographical images also depend on the doping level, film thickness and dopant. The conductivity images, which provide information on the distribution of conducting (insulating) islands surrounded by insulating (conducting) areas, demonstrate that electron conduction across the PANI film is heterogeneous and the conducting homogeneity also depends on doping level, thickness, and dopant. As the doping level of PANI film increased, the size of conducting islands also increased and the I-V curves showed semiconducting and metallic conducting characteristics. As the thickness of PANI film increased, the number and area of conducting domains increased, and the I-V curves showed semiconducting and semi-metal conducting behavior. PANI films prepared from HClO4(aq) (thickness <120 nm) have the smallest degree of conjugation and their I-V curves show semiconducting characteristic no matter they were doped with HCl, H2SO4, or HClO4. The degree of conjugation in PANI films prepared from H2SO4(aq) is the same as those prepared from HCl(aq). These PANI films have the highest conductivity when doping with HClO4(aq), and the I-V curves of all surface show metallic conducting behavior.
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