PVP-free Polyol Synthesis Of Silver Nanowires With Controllable Diameter And Research On Their Application In Transparent Conductive Films

As an important component of photoelectric devices,transparent conductive films have a wide range of applications,especially in the fields of light-emitting diodes,display panels,touch screens and solar cells,which have been attracted wide attention.However,ITO thin films are limited application in flexible electronic devices because of the poor flexibility and easily being destroyed by external forces.In addition,they are also limited their further application in the future due to the relatively complex manufacturing process and deficiency of indium resources.So it is necessary to find alternatives.Silver nanowires are important materials in many fields because of their plasma properties,high transmittance,good conductivity and thermal conductivity.Besides,silver nanowires transparent conductive films have the advantages of high conductivity,good mechanical ductility,easy processing and large-scale manufacturing,making them ideal substitutes for ITO.In order to realize the practical application,it is necessary to reduce the preparation cost of silver nanowires and simplify the preparation process of silver nanowires.At present,silver nanowires are usually synthesized by polyol method in the presence of polyvinylpyrrolidone(PVP).However,these longchain polymer molecules will form an insulating layer around the nanowires.The whole process of removal of PVP is cumbersome,time-consuming and costly.However,in the synthesis process,without the use of organic stabilizers,the silver nanowires have low colloidal stability in aqueous solution and are prone to agglomeration,which will affect the actual performance of silver nanowires.In addition,the diameters and aspect ratios of silver nanowires affect the photoelectric properties of transparent conductive films.The transparent conductive films prepared by silver nanowires with small diameter and large aspect ratio have good photoelectric properties.In order to solve the above problems,this thesis focuses on the controllable synthesis and application of silver nanowires.Silver nanowires with three diameters and high aspect ratios were prepared by polyol method without PVP.The effects of inorganic salts,stirring speed,dropping Acceleration of Ag NO3 Solution,temperature and time of silver nuclei formation on the size of silver nanowires were investigated.The reaction system was enlarged by modified polyol method and macro-scale preparation was carried out.In addition,water-soluble small molecule modifier was synthesized,which improved the dispersion stability of silver nanowires in aqueous solution and solved the agglomeration problem of silver nanowires in aqueous solution.Transparent conductive films were prepared using the as-synthesized silver nanowires,and their optical properties were tested.The specific research contents of this thesis are as follows:1 PVP-free polyol synthesis of silver nanowires with controllable diameterSilver nanowires were prepared by polyol method without PVP.Silver nanowires with average diameters of 55 and 42 nm were synthesized by adjusting the parameters of concentrations of Fe(NO3)3 and Fe Cl3,stirring speed,dropping acceleration of Ag NO3 solution,the volume of ethylene glycol and reaction time which on the size of silver nanowires.Silver nanowires with average diameters of 33 and 40 nm were synthesized by changing the temperature and time of the formation of silver nuclei and the concentration of Na Br.The synthesis mechanisms of silver nanowires was discussed.In addition,the reaction systems of silver nanowires with average diameter of 55 nm and 42 nm was amplified,respectively.Large-scale macrofabrications of 1L,2L and 5L were carried out respectively,and the aspect ratio of silver nanowires was 3000.2 Fabrication and properties of transparent conductive films prepared by silver nanowiresThe water-soluble small molecule modifier was successfully prepared as the modifier of the silver nanowires.The dispersion stability of silver nanowires in aqueous solution was improved when the watersoluble small molecule was capped on the surface of silver nanowires,and the problem of agglomeration in aqueous solution was solved.The modified and unmodified silver nanowires with different diameters,high aspect ratios and modified silver nanowires were dispersed in deionized water.Transparent conductive films were prepared on polyethylene terephthalate(PET)and soda-lime glass(SLG)substrates by spin-coating method.The optimum spinning conditions of transparent conductive films were obtained by adjusting the coating speed,the concentration of silver nanowire solution and coating times.The photoelectric properties of transparent conductive films were evaluated.The results show that the transparent conductive films prepared by small diameter and modified silver nanowires have higher transmittance under the same sheeet resistance.And the transparent conductive films prepared by small diameter silver nanowires have larger transmittance,indicating that diameter is a key factor affecting the optical properties of transparent conductive films.Among them,transparent conductive films were prepared by using silver nanowires with an average diameter of 33 nm on PET substrate,has a transmittance of 97% at the sheet resistance of 20 ?/sq.