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  • 學位論文

溶液相法合成奈米銀及半導體量子點之研究與應用

Solution-based Synthesis and Applications of Nanosized Silver and Semiconductor Quantum Dots

指導教授 : 周更生
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摘要


The solution process was employed throughout this study to synthesis all the materials. With proper reductant, surfactant, precipitant and (-or) additive, nano-silver with various structures and semiconductor quantum dots as well can be successfully prepared. In this work, water- and oil-based silver colloids were chemically synthesized by dextrose as reductant. In the presence of different surfactants silver colloidal particles with fine size and also narrow distribution can be prepared even under quite high concentration. The key is to prepare the insoluble silver salt as the precursor by reacting silver nitrate with urea and sodium hydroxide together in advance before final reduction reaction, by which we can techniquelly avoid the occurrence of instant reduction, and that hence give much time for surfactant molecules to adsorb onto the metal surface to help with well dispersion. By the similar approach Ag-Cu colloidal suspension can be obtained, and its conductive line has been experimentally demonstrated capable of restraining the electromigration. In addition, silver nanoparticles have the unique feature of surface plasmon resonance and are located on the single crystal silicon solar cell device by spin coating method, which has been showed the improvement of the energy conversion efficiency due to the enhanced absorption toward incident photons by silver. On the other hand, the far-infrared (FIR) radiation from a normal subtract can be effectively sheltered after coated with silver colloids on its surface, which shows the potential for silver colloids as an FIR stealth paint. In the synthesis study on silver nanowires, the wires with quite large aspect ratio through an PVP polymer-mediated polyol process was fabricated. The key is to control the accumulation rate of silver ions in the system for the purpose of the formation of wires. During the process, the scale control of the product was achieved by tuning the concentration of either palladium or silver ions. Spreading the silver wires suspension by spraying method onto the transparent substrate can prepare a transparent conductive coating (TCC). The study shows that a coating with longer and thinner wires can give better transmittance performance due to lower deposition threshold for electrical conduction. Also, by following spray of the acrylic resin and then treating with proper baking and light-curing procedures can enhance the adhesive force of silver wires coating to substrate. The nontoxic MPA capping ZnSe quantum dots (QDs) aqueous solution has been prepared by solution process. By tuning the process parameters the reasonable photoluminescence (PL) performance can be obtained. Hydrothermal treatment upon the above solution has been proved capable of help with the growth of QDs to obtain the property of longer excitation wavelength more than 350nm at least, which can pass through the object lens of a normal luminescence microscopy more effectively and hence make it easier to directly observe by human eyes. The following capping molecules replacement by MPS can form a net structure among the QDs to keep from agglomeration to help with stabilization for longer time. Further, in the Mn2+ doping ZnS QDs study, since Mn2+ ion solved in the ZnS lattice gives an PL center within the band gap of ZnS, tuning the composition to alter the relative intensity of bimodal PL peaks can obtain the multiple colors of PL. Also, by the means of doping route, CdPbS composite QDs with near infrared (NIR) emission wavelength around 830nm has been synthesized. The NIR emission was attributed to the defects in the heterogeneous interface during the preparation. NIR emission not only penetrates tissue more effectively but can avoid the disturbance of autoluminescence from the biological molecules. By coprecipitation method along with the proper processing means, the composition distribution inside the QDs that shows a well correlation with the PL intensity can be tunable.

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被引用紀錄


陳奕竹(2012)。硫化鉛量子點轉相技術及其在量子點敏化太陽能電池之應用研究〔碩士論文,國立清華大學〕。華藝線上圖書館。https://www.airitilibrary.com/Article/Detail?DocID=U0016-0908201218195931

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