Formation And Photoelectric Properties Of AgNW/PEDOT Flexible Composite Film Based On Starch Film

Potato starch was used as raw material to synthesize a flexible transparent starch substrate film which can be repeatedly bent and folded.Silver nanowire conductive solution?AgNW?was prepared by polyol method.At the same time,a 5%volume fraction polyethylene dioxythiophene-poly?styrene sulfonate??PEDOT:PSS?solution after secondary doping with ethylene glycol was introduced into the silver nanowire conductive solution to prepare a composite conductive solution.Spin coating method evenly covered the surface of starch substrate film with two conductive liquids to form AgNW conductive films and AgNW/PEDOT composite conductive films with different AgNW deposition densities.The differences between two different types of conductive films and conductive films with different AgNW deposition densities are analyzed and compared.The morphology,molecular structure characteristics and conductive mechanism of the conductive films are investigated with scanning electron microscopy,atomic force microscopy,infrared spectroscopy,Raman spectroscopy,X-ray photoelectron spectroscopy,etc.The conductivity,light transmittance,roughness,flexibility and environmental stability of the composite films are evaluated with four-probe square resistance tester,ultraviolet spectroscopy,roughness meter and thermogravimetric analysis,with the emphasis on the laws and trends of changes in photoelectric properties of products.Using potato starch as raw material and epichlorohydrin as cross-linking agent,adding plasticizer glycerin,a smooth and flat starch substrate film with high light transmittance,good flexibility,high surface activity was obtained by tape casting through the processes of heat gelatinization,cross-linking and plasticization.The infrared spectrum of starch film shows the characteristic absorption peak of C-O-C and hydrogen bond absorption peak,which indicates the formation of ether bond and hydrogen bond between starch molecules.The prepared starch flexible substrate film has light transmittance of 92%,roughness as low as 3.92nm,tensile stress of 29.01MPa,contact angle of 22.8,and high surface activity.TGA thermogravimetric analysis shows that the thermal decomposition temperature of starch substrate film is higher than 250?,and all the performance indexes indicate that the starchfilm is applicable for the use as flexible transparent conductive substrate film.Silver nanowires were prepared by polyol method with silver nitrate?AgNO₃?as silver source,ethylene glycol?EG?as solvent and polyvinylpyrrolidone?PVP?as surfactant.Conductive silver nanowires with diameter of 60nm and length over 20?m were synthesized.SEM surface morphology analysis,X-ray diffraction and UV-Vis spectra showed their one-dimensional linear nanostructures.PEDOT:PSS solution is added to AgNW aqueous solution after secondary doping to synthesize AgNW/PEDOT composite conductive liquid.Raman spectrum shows that PEDOT:PSS solution is successfully separated from PEDOT molecular chain after secondary doping.Meanwhile,PEDOT chain in AgNW/PEDOT composite conductive liquid participates in AgNW network structure,indicating that metal conductive material AgNW and polymer conductive material PEDOT are successfully compounded.AgNW conductive liquid is deposited on the surface of starch film by spin coater to obtain conductive films with different silver nanowire deposition densities.The square resistance of the conductive films decreases with the increase of AgNW deposition amount,but the reduction rate gradually slows down and finally tends to balance.The transmittance decreased linearly with the increase of AgNW deposition.Roughness increases gradually with the increase of deposition amount.When the deposition density is 300 mg/m²,the square resistance Rs is lower than 22.6?/sq,the light transmittance T is about 65%,and the photoelectric excellent value?FOM?is higher than 35.It is a good substitute material for the traditional indium tin oxide?ITO?conductive film.The resistance value of AgNW conductive film is tested after repeated bending tests,and the variation of Rs is less than 5%;Due to oxidation of AgNW,after the AgNW conductive film is placed in the air for 100 days,the square resistance Rs increases by more than 10%and the conductivity decreases.AgNW/PEDOT:PSS composite conductive liquid was spin-coated on the surface of starch film to prepare AgNW/PEDOT flexible transparent composite conductive film.Compared with the AgNW conductive film,the AgNW/PEDOT conductive film transfers charge carriers between the conductive polymer chain PEDOT and the AgNW,which helps electrons to transfer charge through a jump mechanism and improves the conductivity of the hybrid film.The existence of PEDOT:PSS solution weakens the scattering effect of AgNW on light and slightly reduces the light transmittance.At the same time,a smooth and uniform PEDOT:PSS film is formed on the surface of AgNW grid,and the roughness is significantly reduced.The conductive film is repeatedly bent and folded,and due to the fixing effect of PEDOT:PSS,the variation range of square resistance is reduced to 2%,so that the stability and flexibility are enhanced;As for the environmental stability of conductive films in air,the oxidation of AgNW exposed to air increases the square resistance of AgNW films,while the square resistance of AgNW/PEDOT conductive films increases by less than 5%due to the encapsulation effect of PEDOT:PSS,thus further improving the stability.