Electrochemical Properties And Application Of PEDOT:(lignosulfonic Acid)dispersion Regulated By Dopamine

Due to the presence of catechol,dopamine displays a very good reducing ability.Polydopamine is available by simple oxidation and polymerization of dopamine in solution.And polydopamine has many striking properties in optics,electricity,and magnetics.With the structure of catechol and stable free radicals inside,polydopamine is considered to be an organic semiconductor.In addition,polydopamine has the capability to absorb ultraviolet light and works as a photoprotective agent.Based on the above characteristics,polydopamine can not only be used as a coating,but also quickly applied to the chemical,biological,materials science and applied science engineering and technology.However,as the degree of polymerization increases,the water solubility of polydopamine becomes poor.Inspired by the p-doped PEDOT:PSS,a traditional anode modifier,we used PSS with clear chemical structure to disperse polydopamine initially.However,DA and its semiquinone radical were dispersed by PSS to form ordered DA:PSS complex and no polydopamine was formed,and it was confirmed by uv-vis spectroscopy,nuclear magnetic resonance(NMR),electron spin resonance(ESR),elemental analysis and infrared spectroscopy(IR).DA:PSS,with a close neutral pH,had little acid corrosion.Besides,DA:PSS exhibited stable and quasi-reversible electrochemical oxidation behavior,and excellent film-formation capability to reduce the roughness of the film.Consequently,as an indium tin oxide(ITO)anode modifier,DA:PSS has showed the potential of hole injection property in organic light emitting diodes with a significantly improved performance compared with bare ITO device.However,its poor conductivity and high work function are needed to be solved.Our previous study showed that,a potential organic semiconductor,lignosulfonate acid had the structure of phenol,and it could transfer charge and have hole-transport capacity.Lignosulfonate acid was used to dope conductive polymer poly(3,4-ethylenedioxythiophene)(PEDOT),the resulting PEDOT:LS could work as hole transport material in organic solar cells with a comparable performance of the commercial product PEDOT:PSS as hole transport material.But it suffers from the problems such as irreversible redox process,poor cycle stability,which is not conducive to the hole-transportation of the interface and it should be taken into consideration.Take advantage of the property of regulating electrochemical behavior during the polymerization process of dopamine,we further use dopamine to dope PEDOT:LS and improve the electrochemical behavior of PEDOT:LS.What's more,the acid corrosion of PEDOT:LS system is reduced after the doping of alkaline dopamine.In addition,the work function of PEDOT:LS was improved up to 5.47 eV after the doping of dopamine,which matched well with the energy level.And it could act as a hole-extraction material in perovskite solar cell to improve its open circuit voltage,which had great significance of improving the performance of inverted structure solar cell.In this paper,the electrochemical properties of dopamine under acidic condition and PEDOT:LS regulated by dopamine were studied.And a modified method of PEDOT:LS was proposed.