Synchrotron X–ray Structure–resolved Investigation of Titanium Oxide Phthalocyanine (TiOPc) & Its Matrix
|Keywords:||酞菁氧鈦;結構分析系統;同步輻射;X光顯微術;結構解析;TiOPc;GSAS;Synchrotron X–ray;Transmission X-ray Microscopy;structure–resolved|
|Abstract:||感光材料酞菁氧鈦(TiOPc)有著良好的光學吸收性、低毒性、水溶液穩定性、耐熱性和低製造成本，因此廣泛的被應用在雷射印表機中。台大應力所，李世光教授與許聿翔教授團隊已經開發出可利用浸塗法(dip coating)來控制TiOPc分散於系統中的技術。但TiOPc的分佈情形則有待了解。因此本研究利用互補的材料分析工具，以釐清材料結構、分佈與電性間的關係。其中，使用國家同步輻射研究中心的X光繞射和穿透X光顯微術，分成Å尺度和微米尺度進行結構解析。在低掠角X光繞射數據中，利用General Structure Analysis System (GSAS)擬合獲得晶格常數，在透過統計Analysis of variance (ANOVA)分析驗證透過製程和層間距平行的晶格c軸隨製程不同對阻抗有顯著的影響，經過迴歸分析證實晶格c軸和阻抗有正相關。我們另外再應用穿透X光顯微術影像，為了解分子級的層間距透過靜電交互作用儲存電能的效應，解析了TiOPc分子聚集導致阻抗值比預期的阻抗值低的關聯。最終，本研究提出利用浸塗法製程的幾種關鍵參數可以顯著影響TiOPc，晶格尺寸和分子堆疊密度，進而控制其電容值與阻抗值，浸塗法也另可藉由重量百分濃度、浸塗拉速、有機分子比例和浸塗角度，在微米尺度影響層狀結構以創造出不同的分子聚集間距，這樣跨尺度的TiOPc分佈模式同時也影響電容值與阻抗值。最後，針對浸塗法控制參數所預測的樣品厚度，本研究並進一步地利用冷凍切割與掃瞄電子顯微鏡的量測證實了理論與實測的差異。本研究進一步討論浸塗法理論厚度可能不準的出處與提出相應的修正公式。|
Since Titanium oxide phthalocyanine (TiOPc), which is a photovoltaic material, has the properties of excellent light absorption, low toxicity, in aqueous solution stability, good heat resistance and low production cost, it has been widely applied on laser printers. Dr. Chih-Kung Lee and Dr. Yu-Hsiang Hsu, Institute of Applied Mechanics, National Taiwan University, Taiwan has developed a dip coating technology in an attempt to control the distribution of TiOPc within the coated film. It is the purpose of this thesis to carry out further studies to determine the distribution with better accuracy. In this thesis, we have used the complementary analyses of published papers to clarify the relationship between microstructures and conductivities for any arbitrary distribution within coated TiOPc film. Among them, we have used the X-ray diffraction and transmission X-ray microscopies in National Synchrotron Radiation Research Center, Taiwan, to resolve the microstructures of the coated TiOPc in angstrom and micrometer levels. Based on the above experimental results and additional data from the experiments of Grazing Incident X-Ray Diffraction (GIXRD), we have obtained lattice constants by using the available software of General Structure Analysis System (GSAS). We have also verified the relationship between impedance and parameter of c-axis lattice constant by using the software of Analysis of Variance (ANOVA). By applying regression analysis, we have confirmed the proportional relationship between the determined c-axis lattice parameter and the measured impedance. In addition, we have also used transmission X-ray microscopy to study TiOPc films and to understand the electrostatic power stored in between TiOPc layers down to atomic levels. The results have revealed congested TiOPc molecules between layers implying a lower impedance than expected. Also, by tuning several essential factors used in the dip-coating process that affect the lattice constant and molecular stacking density of the coated TiOPc film, we have found ways to control its capacitance and impedance. Apart from that, dip coating can also affect the capacitance and impedance of TiOPc caused by different cross-scale distribution patterns resulting from different molecular stacking density within the layer structure in micrometer level. Finally, regarding to the control of the thickness of specimens by dip coating, we suggest to utilize low-temperature-cut method and scanning electronic microscopy to find the differences between expected and experimented results. At last, we have studied the discrepancy between desired and measured thicknesses in dip-coated TiOPc films and suggested some feasible methods to reduce the discrepancy with a help of a simple formula.
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