Synthesis Of Cathode Material PEDOT For Solid Tantalum Capacitors And Study On Photoelectric Properties

In many electronic devices,Ta/MnO₂ solid tantalum capacitors with MnO₂ as the cathode are widely used in commercial electronic products due to their high stability and reliability and the high capacity efficiency provided by the porous structure of tantalum anode.But MnO₂ as the cathode material when there is a poor electrical conductivity,thermal runaway failure mode and higher equivalent series resistance（ESR）,conductive polymer poly（3,4-thiophene ethylene 2 oxygen）（PEDOT）instead of MnO₂ do counter electrode,can obviously improve the performance of the condenser to improve its frequency characteristics and durability,has become one of the important choice of tantalum capacitor cathode materials.In this paper,PEDOT solution was prepared based on solid tantalum capacitor cathode material and its photoelectric properties were studied:（1）PEDOT:PSS solution was prepared by traditional emulsion polymerization and miniemulsion polymerization.The influence of different reaction conditions on the performance of PEDOT:PSS solution was investigated by adjusting the amount of surfactant,the optimization of the catalytic system and the stirring mode.Compared with traditional emulsion polymerization,miniemulsion polymerization has better performance in particle size homogeneity,potential stability and doping degree.A series of PEDO:PSS conductive solutions were obtained by miniemulsion polymerization.Optimization of miniemulsion polymerization process to determine the best process parameters:that is,the molar ratio of PSS to EDOT was 3:1,the molar ratio of FeSO₄?7H₂O to EDOT was 0.3:1,and the molar ratio of KPS to EDOT was 1:1.（2）The influence of the above dopants on the conductivity of PEDOT films was investigated by using the secondary doping method and using zinc chloride（ZnCl₂）,ethylene glycol（EG）,sorbitol,hexafluoracetone and other dopants respectively.The results show that ZnCl2 and ethylene glycol as dopants have obvious effects on improving the conductivity of PEDOT films.Among them the effect of ethylene glycol is the most obvious,compared with the original PEDOT:PSS film,the conductivity increased by 200 times,and the conductivity of doped film was 0.16s/cm.（3）The sample with the best performance prepared in the first two chapters is selected as the cathode material of solid tantalum capacitor to characterize the related performance of the capacitor.Since the particle size prepared by miniemulsion method is lower and it is easier to impregnate the inside of tantalum block,The material has obvious improvement on leakage current.