Preparation Of Silver Nanowire Conductive Ink And Its Solution Processing For Flexible Transparent Conductive Films Fabrication

As an important photoelectric functional material,transparent conductive film is widely used in display devices,touch devices,transparent heating devices,solar cells,organic light-emitting diodes,electromagnetic shielding and other related technical fields.Indium tin oxide,which currently dominates the market,has its limit on the development of flexible electronic devices due to its brittleness.Silver nanowire based flexible transparent conductive film is a kind of novel but better material to replace indium tin oxide,with great application prospects.This paper mainly introduces the preparation of silver nanowire flexible transparent conductive film,including the polyol synthesis,purification,conductive ink formulation,coating process and its application in flexible touch and electromagnetic shielding.In the research on the synthesis and purification of silver nanowires,by adjusting the concentration of Na Br and Na Cl in the reaction solution,the controllable preparation of silver nanowires of different lengths with diameters of 42nm,35 nm,30 nm and 26 nm can be achieved.Reaction under nitrogen atmosphere,the dissolved oxygen can be removed,and thus the yield of silver nanowires was improved.The surface modification of silver nanowires with anti-settling agent improves the dispersion of silver nanowires and solves the problem of silver nanowires agglomeration during centrifugation.Finally,the silver nanowires are efficiently purified after anti-settling agent modified centrifugation and filtration.During the study of silver nanowire conductive ink formulation and its coating process,binder 0.2 wt.%was added to the ink to increase the viscosity and dispersion stability of the ink,and Triton X100 was added to improve the wettability of the ink to the substrate.The sheet resistance of the transparent conductive film was adjusted according to the concentration of silver nanowires in the ink.The best coating process parameters for silver nanowire conductive ink are:coating thickness10μm,coating speed 20 mm s^-1 and drying temperature 130℃10 min;the best solid content of acrylic resin in OC ink is 0.8 wt.%.After coating the OC layer,the adhesion of the conductive layer to the PET substrate is successfully improved without affecting the photoelectric performance of the conductive film;the silver nanowires’preparation and purification method and the feasibility of the conductive ink formulation mentioned in this paper have been fully proved through the roll-to-roll pilot test,achieving a large-scale production of nanowire transparent conductive film with a sheet resistance of 55Ωsq^-1,a transmittance of 92.3%and a haze of 0.97%.The flexible touch device prepared by patterning the conductive film has preliminary functions.Transparent conductive films with different sheet resistances can be used in the field of electromagnetic shielding,as the sheet resistance decreases,the electromagnetic shielding effectiveness of the transparent conductive film increases,where the electromagnetic shielding performance of the conductive film with the square resistance of 6.2Ωsq^-1 reached 31.93 dB.