Preparation Of Macro Amount Of Silver Nanowires And Their Application In Flexible Transparent Electrode

The polyol method for preparing silvernanowires was modified, and the effects of various parameters, including temperature, silvernitrateconcentration, molecular weight andconcentration of polyvinylpyyolidone?PVP?, type and concentration ofhalide salts, feeding rate and mode, on the morphology of as-prepared silvernanowires were investigated. The nucleation and growth mechanisms of the silver nanowires were explored, and the interactions among various parameters were discussed. Furthermore, a facile and efficient one-pot process was established for the preparation of macro amount of silvernanowires, with the hope to establish the experimental and technical grounds for the large-scale applicationof silvernanowires. In the meantime, the as-prepared silver nanowires were used intransparentelectrodes. The optoelectronic performanceof the as-fabricated transparentconductive films of silver nanowires was evaluated, and the effect of the diameter of silvernanowires on the optoelectronic performance of the transparentconductive films was studied. Themain contents and results of this thesis are as follows:?1? Effect ofparameterson themorphologyof silver nanowiresSilver nanowires were prepared by polyol method withNiCl₂ as the controlagent. The effects of temperature, silver nitrate concentration, molecular weight andconcentration of PVP, molar ratio of PVP to AgNO₃, molar ratio of NiCl₂ to AgNO₃, feeding rate, and the type of the protective gases on the morphology of silver nanowires were investigated. The morphology and microstructure of the as-prepared silver nanowires were analyzed by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The nucleation and growth mechanisms of silver nanowires were discussed. Results indicate that the amount of the by-products during the preparation of silver nanowires can be effectively reduced while the experimental parameters are properly adjusted, and the target silver nanowires with a diameter of 40-100 nm can be obtained in a yield of above 95%.?2? Preparation of macro amount of silver nanowires by one-pot methodConventional methods for preparing silver nanowires often require the dropwise addition of the reactants and can provide the products only at microgram or gram scale. This means that they cannot satisfy the industrial demand, due to the limit in affording macro amount of silver nanowires. Therefore, the effects of the feeding mode and temperature on the yield of silver nanowires were investigated at-depth, and the purification and storage of the silver nanowires were primarily explored, thereby providing experimental ground and technical support to their commercial application. Results indicate that macro amount of silver nanowires can be obtained by one-pot method while the heating process is properly adjusted?the volume of the reactor is 5 L, and the output of a single batch of reaction is over 10 g?.?3? Preparation oftransparent electrode of silvernanowires and study of its optoelectronic propertiesFlexible transparent conductive electrode was prepared by spin-coating withsilvernanowire with differentdiametersas the conductivematerial and polyethylene glycol terephthalateas the matrix. The effect of the diameter of the silver nanowires on the optoelectronic properties of the as-fabricated transparent electrode was investigated.Results indicate that the transparentelectrode with good performance?transmittance above 90%, sheet resistanceabout 70 ?? can be obtained by optimizing the technological condition. Besides, the optoelectronic properties of the as-fabricated transparent electrode tend to be improved with increasing aspect ratio and decreasing diameter of the silver nanowires.?4? Preparation of silvernanowires with different diametersThe diameter of silver nanowires has a significant effect on the optoelectronic properties of the transparent conductive films, and the preparation of ultrathin silver nanowires?with a diameter below 25 nm? is the key and challenge to develop high-performance transparent conductive film. Therefore, attempts were made to prepare ultrathin silver nanowires based on the aforementioned one-pot method while NaCl, NiCl₂ and NaBr were adopted as the manipulating agents. Results indicate that, with NaCl-NaBr or NiCl₂-Na Br as the manipulating agent and PVP as the modifying agent, ultrathin silver nanowires with an average diameter of 23 nm can be obtained as expected.