Study On Preparation And Properties Of Graphene Oxide Based Ink For Inkjet Printing

With the rapid development and popularization of electronic devices,people's lives become more colorful and convenient.In recent years,people have made higher demands on electronic devices and hope to expand the functions and application range of electronic devices further.An promising development direction is the flexible electronic devices.It goes beyond specific shape limitation because of its bendable and foldable characteristics so it has been received widespread concern.The study on using simple and low cost methods to manufacture flexible electronic devices has become a focus of attention.Inkjet printing is a digital control printing technology.Besides the advantages of simple operation,high efficiency and low cost,it is compatible with flexible substrate,so it can be used in the manufacture of flexible electronic devices.Graphene is a kind of carbon material.The carbon atoms bond with sp2 hybrid orbitals and form a hexatomic ring.Graphene is a twodimensional plane that contains many hexatomic rings.Because of its special structure,graphene has a large specific surface area,high electrical conductivity,high thermal conductivity,high transmittance,and excellent mechanical properties.In this thesis,graphene oxide(GO)ink and graphene oxide incorporated with silver nanoparticles(Ag NPs-GO)ink were prepared.Firstly,GO sheets were dispersed in mixed solvent consisting of deionized water(DIW),ethylene glycol(EG),and ethanol(ET).After ultrasonic grinding,GO sheets showed a sheet diameter below 1.0 ?m and a thickness of 1.2 nm.The GO ink concentration was 4 mg/ml and the volume ratio of DIW,EG and ET in the mixed solvent was 1 : 1 : 1.GO Ink had the good printing performance(no nozzle clogging,stable jetting and no satellite droplet)and long-term stability.The viscosity and surface tension of GO ink were 7.41 m Pa·s and 36.44 m N/m respectively.Z value was 3.81,which met the needs of inkjet printing.The hydrophilicity of the polyethylene terephthalate(PET)substrate after oxygen plasma treatment at different time was studied.It was found that the contact angles of GO ink on the PET substrate was reduced from 54.5° to 4.2° with the treatment time increasing from 0 min to 9 min,and the quality of the printed pattern was the best when the treatment time was 3 minutes.Meanwhile,graphene oxide incorporated with silver nanoparticles(Ag NPs-GO)was synthesized using chemical reduction method.The effect of the mass ratio of GO to silver nitrate(Ag NO3)on the distribution and morphology of silver nanoparticles on GO surface was studied.When m(GO): m(Ag NO3)= 1 : 2,the silver nanoparticles showed spherical morphology and uniformly dispersed on GO surface.When the concentration of Ag NPs-GO ink was about 1.7 mg/ml and the volume ratio of DIW,EG and ET in the mixed solvent was 1 : 1 : 1,the ink exhibited the good printing performance.GO and Ag NPs-GO pattern were printed on PET substrate with oxygen plasma treatement,and it was found that both GO ink and Ag NPs-GO ink can jet stably from the nozzle without the satellite droplet.The GO pattern printed on PET substrate had no coffee-ring effect.When the number of printed layers increased from 10 to 60,the sheet resistance of printed pattern obviously decreased from 24.22 M? to 1.49 M?,and the surface of printed pattern had a large number of networklike protrusions.Printed pattern was treated by intense pulsed light(IPL).The color of GO pattern after IPL treatment changed from brown to black,and a large number of cracks formed on the surface of GO pattern.With the voltage increasing,the sheet resistance of the printed pattern also was efficiently decreased.For the 20-layer GO pattern,the pattern surface began to delaminate at the voltage of 3 k V.In addition,the GO patterns with 30 layers or more were inflated and the surfaces were like volcano after IPL treatment.