PEDOT AC Electrodeposition Preparation And The Matterial Transport Mechanism

Physicochemical hydrodynamics is an important branch of modern hydrodynamics.It mainly discusses the interaction between fluid flow and physical and chemical processes.This paper mainly explores the physicochemical hydrodynamics of electrochemical processes.In the process of electrochemical deposition,the reactants are first transported from the electrolyte solution to the electrode surface,then reacted on the electrode surface and deposited on the electrode surface.The transport models of substances in electrolyte solutions mainly include diffusion,electromigration and convection.When the electric signal of electrochemical reaction is alternating current,due to the uneven distribution of electric field,the particles will polarize and generate electrostatic moment.In an AC inhomogeneous electric field,the polarized particles will be moved by dielectrophoresis force.Based on the theory of physicochemical hydrodynamics,the main work of this paper is as follows:1.Using the mixed aqueous solution of 3,4-ethylenedioxythiophene(EDOT)and poly(sodium 4-styrene sulfonate(NaPSS)as electrolyte and AC electrochemical polymerization deposition method,P with different morphologies(membrane,dendritic,linear)was prepared by adjusting the electrical parameters(voltage amplitude,frequency,DC bias)during the polymerization process between Pt microelectrodes.EDOT:PSS structure.Scanning electron microscopy(SEM),atomic force microscopy(AFM)and Raman spectra(Raman Spectra)were used for characterization and analysis.The results show that:(1)The higher the voltage amplitude,the more nucleation points will be generated on the electrode.(2)Voltage frequency affects the formation of PEDOT:PSS morphology.When the frequency increases,the morphology changes from film to dendritic and linear.(3)DC bias affects the direction of material growth during deposition.PEDOT:PSS tends to grow at positive bias.(4)Voltage amplitude and frequency affect the molecular structure of PEDOT:PSS.With the increase of voltage amplitude and frequency,the surface of PEDOT:PSS is uneven,and the structure defects such as holes and broken chains will be formed in the interior of PEDOT:PSS.2.Charge transfer kinetics and material transport mechanism of EDOT monomer and PSS~-in the process of polymer deposition were studied by chronoamperometry,cyclic voltammetry and AC chemical impedance spectroscopy.The results show that:(1)The oxidation potential of EDOT monomer is+0.9V and the peroxide potential is+1.2V.(2)In the process of polymer deposition,the diffusion of material is limited,and the reaction rate of electrode is affected by the mass transfer rate in solution.(3)Polymerization and deposition reaction process is mainly divided into two steps:a)EDOT monomer and PSS~-substance adsorbed on the electrode surface.b)EDOT and PSS~-were deposited on the surface of the electrode to form PEDOT:PSS.(4)The electrochemical polymerization deposition process and the mass transfer process of the substance in the solution affect each other in the same time constant.3.The correctness of transport mechanism is verified by simulation with COMSOL software.The experimental phenomena are explained by the transport mechanism of substances in solution.The conclusions are as follows:(1)During the electrochemical polymerization and deposition process,the EDOT monomer oxidized to form cationic free radicals.Cationic radicals migrate along the electric field and react with other monomers to form dimers.Dimers continue to oxidize to form oligomers.(2)Neutral particles,such as monomers,dimers and oligomers,are affected by dielectrophoresis force in an inhomogeneous electric field,and concentrate in the central region between the pairs of electrodes.(3)The concentration of particles in the central region increases.When the particles are close enough,they will form dipoles through the cohesive force between them.(4)The higher the voltage amplitude and frequency,the stronger the dielectrophoresis,electrophoresis force and the aggregation force of the molecule,and the closer the PEDOT:PSS structure formed by the aggregation.4.Organic semiconductor(OS)channel layers with different morphologies,such as thin films,wires and dendrites,were deposited between Pt microelectrode pairs by alternating current deposition using a mixture of 3,4-ethylenedioxythiophene(EDOT)and poly(4-styrene sulfonate(NaPSS)aqueous solution as electrolyte.Organic electrochemical transistors(OECTs)were fabricated using NaCl electrolyte as gate medium,Ag/AgCl electrode as gate,one of the Pt microelectrodes as source and the other as drain.The effects of different morphologies and structures,doping different concentrations of graphene quantum dots on device performance were investigated.The repeatability of PEDOT:PSS organic electrochemical transistors prepared by AC chemical polymerization deposition was verified.The results are as follows:(1)The performances of PEDOT:PSS channel layer OECTs with different morphologies are analyzed.The results show that the performances of film channel layer OECTs are the best.(2)Graphene quantum dots are doped to explore the effect of doping graphene quantum dots on device performance.The results showed that OECTs had the best performance when the mass concentration of GQDs was 2μg?L.(3)Repeatability experiments were carried out on OECTs fabricated by alternating current chemical polymerization deposition.The results show that the microelectrodes have the same size and the same electrical parameters.This method has good repeatability.