Study On Electrochromic Properties Of POMs-Conjugated Polymer Composite Films And Devices

Polyacid is the abbreviation of Polyoxometalates(POMs),which is produced by the condensation and dehydration of simple oxometalates under certain pH conditions.The cluster compound with MO₆octahedron as the basic unit,POMs have high electrochemical activity,good reversibility,and high electrochemical stability.Because in the process of redox,the multivalent state of metal ions corresponds to the change of different colors,which is a very potential electrochromism(electrochromism,EC)material.In this thesis,the effect of POM on the bifunctional performance of electrochromic and energy storage in working electrode material and the effect on charge balance and storage in electrochromic devices in POM as counter electrode material were studied.Extensively studied electrochromic materials include conjugated polymers,transition metal oxides,and small organic molecules.In recent years,single organic electrochromic materials or inorganic electrochromic materials have been unable to meet people's requirements in practical applications due to their defects in performance.The use of organic/inorganic composite electrochromic materials has gradually become the focus of research.In the first part,MnO₂-PEDOT-PMo₁₂ternary composite thin films were prepared by a simple distributed co-deposition.The MnO2substrate has a three-dimensional staggered network structure and has an excellent theoretical specific capacitance,and its thickness is adjusted so that its color has little effect on the overall transmittance;PEDOT effectively improved the electrical conductivity of the composite film and played the main electrochromic effect;PMo₁₂further improves the overall pseudocapacitance level;and because it has the same tinting voltage as PEDOT,it also helps a lot in optical contrast.The ternary composite film prepared under the optimal conditions has an effective transmittance of 52.3%,while maintaining an areal capacitance of 14.2 m F/cm~2at a current density of 0.1m A/cm~2.In the second part,the TiO₂-PMo₁₂composite electrode material was prepared by spin coating method combined with electrodeposition.It was used as the counter electrode and the spin-coated PR-Br conjugated polymer working point film was assembled into electrochromic devices(ECDs).PMo₁₂significantly improves the EC performance of the device.The efficient charge transfer between PMo₁₂and TiO₂promotes the overall charge balance capacity of the counter electrode,resulting in a higher?T(-2.0 to 1.0 V)in the device at lower applied voltage.An attempt is made to explain the mechanism of the action of PMo₁₂through the Nernst equation and energy level electron transfer.