The Preparation Of High Aspect Ratio Silver Nanowires And Its Application In Transparent Conductive Film

Abstract:Silver nanowires (AgNWs), an important branch of silver nanomaterials, has become a good choice of producing flexible and transparent conductive materials because of its flex resistance, high transparency, efficient electrical and thermal conductivity, and so on. So far, there are a lot of methods to prepare AgNWs. And polyol process is much favored by researches because of its simple, controllable form and size, and suitable for mass production. But AgNWs produced by the classic polyol process have some shortcomings such as dimensional non-uniformity, low purity, low yields, and small aspect ratio, etc. Different from predecessors’method, the way of addition of samples has been changed from dropwise adding to one-time pouring in this paper. And the improved alcohol reduction method successfully prepares AgNWs with high purity, uniform size and high aspect ratio. Besides, the transparent conductive film with high transmittance and good electrical conductivity is prepared by the combination of AgNWs and titanium dioxide (TiO2). The main contents are summarized as follows:By employing polyol process with ethylene glycol as the reducing agent and solvent, silver nitrate as a source of silver, halide as seed inducer, polyvinyl pyrrolidone (PVP) as stabilizing agent and structure-directing agent, this paper studied the influences of conditions on the form and size of AgNWs from seed inducers [copper chloride (CuCl2), sodium chloride (NaCl) and iron chloride (FeCl3)], anti-seed reaction time and reaction temperature, respectively. And the optimum conditions were summarized as follows:CuCl2as seed inducer, the reaction temperature is160℃, and the reaction time of seed crystal is6min. In this way, the AgNWs with uniform size and form, less particles, and an aspect ratio greater than500(length50-60μm, diameter about90nm) is produced.By using sol-gel method with tetrabutyl titanate as precursor, ethanol as a solvent, acetylacetone and hydrochloric acid as an inhibitor, and using the hydrolysis and condensation reaction of tetrabutyl titanate prepared TiO2sol with good stability and high transparence. And when the acetic acid is an inhibitor, pH is2, n(H2O)/n(Ti(OBu)4) is4and n(CH3CH2OH)/n(Ti(OBu)4)=40, the overall performance of the prepared solution is best.The impact of AgNWs aspect ratio and titanium dioxide film on the conductive properties has been explored by combining AgNWs’ and TiO2’s solutions, and using spin-coating method to prepare transparent conductive films, finding the overall performance of AgNws-TiO2films is best when the aspect ratio is400-600, with up to90%light transmission and sheet resistance of about30Ω. It also concludes that TiO2is beneficial to conductive features, and enhances the conductivity of AgNWs-TiO2film greatly.