Preparation And Characterization Of Flexible Transparent Electrodes Enabled By CVD Graphene Combined With Silver Micro-nano Structures

The current mainstream transparent electrode material indium tin oxide(ITO)is difficult to meet the growing demand for flexible electrodes due to mechanical flexibility and resource cost limitations.Graphene is expected to become a new generation of flexible transparent electrode materials due to its excellent light transmission,electrical conductivity and mechanical toughness.However,the flexible transparent electrode made of single-layer pure graphene still has deficiencies in conductivity,bending resistance and environmental stability.In this work,CVD singlelayer graphene was combined with silver nanowires and silver microgrids,respectively,to obtain a combined flexible transparent electrode with better overall performance.The main findings are as follows:(1)CVD single-layer graphene flexible transparent electrode on PET substrate was prepared and characterized.Through the exploration of the CVD process,high-quality single-layer graphene was prepared: Raman characterization ID/IG=0.06 proved that there were very few defects,and the AFM characterization thickness was less than 0.6nm.The transmission rate of the CVD single-layer graphene transparent electrode on the PET substrate in the visible light band is 97.6%,and the average square resistance is 3.3 k?/sq.(2)Flexible transparent electrodes composed of CVD single-layer graphene and silver nanowire with good performance were prepared and characterized.First,ultraslender silver nanowires with length-to-diameter ratio greater than 1000 and flexible electrodes were prepared by hydrothermal method,spin coating and mechanical pressure(light transmittance at 550 nm is 91.4%,square resistance is about 46.4 ?/sq).Secondly,the properties of the flexible combined transparent electrode obtained by compounding CVD single-layer graphene and silver nanowires are as follows: ?=550nm,the light transmittance is 88.9%,the square resistance is 37.5 ?/sq,and the quality factor is 82.8(higher than graphene flexibility 4.8 for transparent electrodes and 55.7for commercially available flexible ITO electrodes).In the bending resistance and environmental stability tests,the conductivity of the flexible combined transparent electrode is only 1/3 of the single-phase silver nanowire electrode,showing a more reliable synthesis than the single-component CVD graphene or silver nanowire electrode performance.(3)Flexible transparent electrodes composed of CVD single-layer graphene and patterned silver microgrid with the excellent comprehensive performance were prepared and characterized.Using photolithography,electron beam evaporation and lift-off processes to prepare silver microgrids on PET flexible substrates,and then combined CVD single-layer graphene with it,the resulting flexible combined transparent electrode has a light transmittance of 87.9 at ?=550 nm %,square resistance13.4 ?/sq,quality factor 211(4 times that of commercially available flexible ITO electrodes).In the bending resistance and environmental stability test,the conductivity of the combined flexible transparent electrode decreased by only 1/4 of the pure silver microgrid electrode.CVD single layer graphene and silver microgrid combined flexible transparent electrode has more excellent comprehensive performance than the above CVD graphene silver nanowire combined electrode.