Preparation Of Silver Nanowires And Their Application In Smart Glass

Silver nanowires（AgNWs） have wide applications in many fields, such as optics, electrics, biology, and etc., due to their high specific surface area, high reactivity, and good conductivity. Recently, more and more attentions have been paid to the fabrication and application of AgNWs. Although there are many literatures reporting the preparation of AgNWs, it is still a difficult problem to produce AgNWs with ultra-high length/diameter ratio. Smart glass is a kind of functional glass that would become transparent under the role of electric field. But they haven’t been widely used due to their high cost. It also possesses very important academic and application value to prepare transparent conductive electrode（TCE） by adopting AgNWs and apply TCE to smart glass. And few reports were published in this field. This dissertation investigated the effects of preparation parameters on the morphology of AgNWs. And SEM, XRD, and UV-Vis were used to characterize the samples. Finally, the application of AgNWs in smart glass was probed into.Firstly, one-step ethanol-thermal reduction was adopted to fabricate AgNWs with ultra-high length/diameter ratio and uniform diameter. And the effects of some preparation parameters, including the concentration of AgNO₃, the ratio of AgNO₃ and PVP, reaction temperature, nucleation control agent, different solvent, PVP molecular weight, and etc., on AgNWs were studied. Some explanations for these phenomena were given. It was found that the concentration of AgNO₃ and reaction temperature exerted certain effect on the formation of twin crystal nucleus（MTPs）, thus affecting the uniformity of AgNWs. When the ratio of AgNO₃ and PVP decreased to a value, AgNWs become fold-line. This is mainly induced by new twin crystal nucleated at the end of AgNWs. It was also found that the solvent made great effect on the product of AgNWs. Three solvent, i.e. glycol, pentaerythritol, and 1, 3–butanedio, w ere used to synthesize AgNWs, and the obtained AgNWs had significant difference. Besides, we also found that AgNWs with uniform morphology can be obtained by adding PVP with high molecular weight rather than low molecular weight. Finally, by using mixture solvent and other suitable preparation parameters, AgNWs with average length of 100 μm, average diameter of 70 nm, and length/diameter ratio of about 1400, were obtained.Transparent conductive electrodes were prepared by coating AgNWs onto glass substrate. The conductance and transmittance of the samples were measured. We found that TCE fabricated with AgNWs with smaller diameter and longer length had better performance. After heat treatment at certain temperature for some time, some junctions between AgNWs would melt together, thus leading to the sharp decrease of the resistance while no obvious change of the transparency of the TCE. The TCEs with good conductance and transmittance were made into liquid crystal boxes which were further used to fabricate smart glass. The different parameters for preparing smart glass were investigated, mainly including liquid crystal content, thickness of liquid film, light intensity. Eventually, a smart glass sample with a threshold voltage of 20 V and a transmittance of 74% at 550 nm was achieved.