Experimental Study On Reduction Of Graphene Oxide Films Using Direct Laser Writing

Graphene,a two-dimensional carbon crystal with the thickness of a single atomic layer,has attracted much attention in the field of material science and modern physics since its discovery in 2004.It has excellent electronics,optics,thermodynamics and other properties,making it widely applied in the fields of electronic information,energy communication and biomedicine.Graphene-based electronic devices are the most important among graphene applications,however,after nearly ten years of research are still unable to achieve large-scale applications,the main reason is that traditional technology can not meet the production of new nano materials and devices processing industrial manufacturing requirements,especially in large-scale preparation,forming patterns,electrical property regulation and so on.The GO reduction method is widely used in the preparation of graphene,which has the advantages of strong compatibility,easy control and large-scale production.The traditional GO reduction methods include heat treatment and chemical reduction.The former needs the aid of inert gas under high temperature annealing?>1000??,and the energy consumption is large.The latter needs chemical reductant and has residual pollution.Moreover,these two methods have poor compatibility with industrial manufacturing technology of graphene-based devices,and need independent patterning processing links,which increases the complexity of device fabrication.In recent years,the laser direct writing reduction technology solve these problems.With only one direct writing process,the insulating GO can be reduced to conductive graphene and made into any micro pattern without any pre-designed patterned substrate or shadow mask.,has the advantages of clean,no pollution,low cost,easy operation,high stability and flexibility.In this paper,we use high speed controlled focused CO₂ picosecond laser direct writing to reduction GO thin films at room temperature,and GO graphene patterns are successfully prepared at the same time.In the process of laser direct writing reduction,we can control the conductivity of RP-GO accurately by controlling the thickness of the film and the laser power.The specific research contents are as follows:?1?High quality GO films were prepared on quartz substrates successfully by spin coating method,and the effects of the relevant spin coating parameters on the patterned reduction of the films were also studied.Under the condition of 3mg/ml,1000rp and30s,GO thin films with uniform texture were successfully prepared,which laid a solid foundation for subsequent laser direct patterning reduction treatment.?2?The GO films were processed by laser direct writing and characterized by Raman spectroscopy.The results showed that the D band and G band were narrowed and not shifted after reduction.I_D/I_G decreased from 0.86 to 0.80 after reduction,accompanied by the appearance of 2D peak.Secondly,the X ray photoelectron spectroscopy?XPS?was used to characterize.The results showed that the O_1s peak intensity after the reduction was greatly reduced.Finally,combined with further validation of X ray diffraction?XRD?,it is proved that laser direct writing reduction can effectively remove the oxygen-containing functional groups in GO and regulate the degree of reduction of GO,thereby preparing graphene structure.?3?Laser direct writing patterning of GO thin films.Various micropatterns were prepared according to the precoding procedure.The overall structure pattern was observed by optical microscope,and the microstructure was characterized by atomic force microscopy?AFM?and scanning electron microscope?SEM?.The edges of the micro patterns are clearly visible,and the quality of patterning is high.The structure characteristics of the micro patterns can be controlled by adjusting the number of spin coating layers and laser power,which proves the high controllability and flexibility of laser direct writing patterned GO films.?4?One-dimensional linear micro circuit and two-dimensional planar graph were patterned through laser direct writing,respectively.The electrical properties were tested by using precision semiconductor parameter analyzer and four probe tester,it is found that the laser power threshold of patterned one-dimensional linear structure and two-dimensional surface structure reduction were 75mW and 40mW,and there is an optimum laser power can make the micro structure conductive performance is best;When the laser power is fixed,the higher the number of layers is within the range of15/20/25,the better the conductivity of the microstructures is.In a word,we can effectively regulate the electrical properties of the RP-GO microstructures by controlling the number of spin coating layers and laser power.