Three-dimensional Tunable Orientation Of Silver Nanowires In Nematic Liquid Crystals Via Photo-alignment

With the development of liquid crystal materials,liquid crystals are widely used in optical devices,and changing the photoelectric characteristics of liquid crystal devices is a current research hotspot.Doping nanomaterials in liquid crystals is one of the methods to change the photoelectric properties.Different nanoparticles will interact with liquid crystal molecules.Selecting the required nanoparticles to dope the liquid crystal can obtain the required photoelectric characteristics.Compared with synthesizing different types of liquid crystals,this method is more convenient and cheap.Current studies have shown that doping nanomaterials in nematic liquid crystals can effectively change the optoelectronic properties of liquid crystals.Nanomaterials have unique quantum size effects,surface plasmon resonance effects,etc.These properties can be transferred to liquid crystal molecules without disturbing the orientation and distribution of the original liquid crystal molecules.This new research idea has great application potential in the field of liquid crystal display.Among many nanomaterials,silver nanowires（Agnano-wires,Ag NWs）have better optical transmittance and surface resistance than other materials,and are a very promising nanomaterial with high thermal conductivity and electrical conductivity.,and has good composite properties with other nanomaterials.However,how to realize the three-dimensional orientation of Ag NWs in nematic liquid crystals is still a difficult problem.In this paper,based on the method of photo-alignment and applied voltage,the three-dimensional orientation of silver nanowires in liquid crystal（5CB）/silver nanowire composites is solved,and the feasibility of flexible displays is studied.First,under a polarizing microscope,it was found that the silver nanowires were arranged in an orderly manner and perpendicular to the director n of the liquid crystal molecules,and then the composite material of the silver nanowires/liquid crystals was rotated by 90°and the photo-alignment was performed again,and the result was consistent with the previous alignment characteristics.Always.And the orientation order parameters of the silver nanowires are all above 0.9.Then,the photo-alignment of the silver nanowires was studied for the third time using a mask.On the basis of the above two-dimensional orientation,an electric field is generated in the silve nanowire/liquid crystal composite material by using an applied voltage.The experiment found that as the applied voltage increases,the angle between the long axis of the silver nanowire and the glass substrate also changes.increase.Combining the photo-alignment technology and the method of applying voltage,the silver nanowires can be oriented three-dimensionally.In addition,the threshold voltage（Vth）and response time of the composite material doped with silver nanowires and non-doped silver nanowires were measured,and the results showed that The threshold voltage of 5CB liquid crystals doped with silver nanowires is larger than that of undoped ones.,but there was a large change in t_on,and there was no difference in t_off Variety.Finally,the mixed solution of silver nanowires and liquid crystals in the composite material was solidified with 365nm ultraviolet light,and then separated to produce a flexible film.The experiment found that the film still retains the display function at the nanometer level.In summary,based on photo-alignment,this paper studies the characteristics of silver nanowires in nematic liquid crystals,realizes the orientation and reorientation of silver nanowires,solves the three-dimensional problem of silver nanowires,and also measures The photoelectric properties of liquid crystals doped and undoped with silver nanowires were compared,and finally,flexible films were fabricated by photocuring technology.This has very good scientific research significance and practical application value for the manufacture of liquid crystal display screens and optoelectronic devices.