Preparation And Photoelectric Properties Of Poly(3,4-ethylenedioxyselenophene) And Its Derivatives

Conducting polymers are electrically conductive conjugated polymers that have been electrochemically or chemically doped,creating plastics electronics and winning the 2000 Nobel Prize in Chemistry.Poly?3,4-ethylenedioxythiophene?and its derivatives?PEDOTs?have excellent electrical conductivities and stability,etc.,and are widely used in the field of organic electronics,and have long been a research hotpot in this field.Compared with PEDOTs,its selenophene analogue,poly?3,4-ethylenedioxyselenophene??PEDOS?,showed unique advantages in electrochromic performances.This is mainly due to the fact that selenium atoms have better polarization and higher carrier mobility than sulfur atoms,so polyselenophene has lower band gap and redox potential than polythiophene structure.Studies on the ring-expanding derivative structure of PEDOS,poly?3,4-propylenedioxyselenophene??PProDOS?further improved the solubility and molecular rigidity of PEDOS,and obtained better flexibility and high coloring efficiency and other advantages.However,compared with PEDOTs,due to the difficulty of synthesis,the research on PEDOS and its derivatives has only been paid more and more attention in recent years.There is still broad space for the preparation and development of electrochromic properties of PEDOS.This thesis is devoted to the efficient synthesis of EDOS and its derivatives.Through electrochemical and chemical oxidative polymerization strategies,PEDOS and its derivatives films materials are obtained in different electrolyte systems.The physicochemical properties and photoelectric properties of the system are systematically studied.The application of organic electronics in the field of electrochromism was mainly discussed,for the subsequent research to establish a method-structure-performance correlation law basis.The specific studies are as follows:1.Electrochemical polymerization of 3,4-ethylenedioxyselenophene?EDOS?in an aqueous emulsion system and electrochromic properties of polymer films.The EDOS monomer was designed and synthesized by optimized route.The electrochemical behavior of EDOS was studied in aqueous microemulsion,which was mainly composed of sodium dodecyl benzene sulfonate?SDBS?as surfactant,LiClO₄ as electrolyte and deionized water as solvent,and the polymer PEDOS films were obtained.The electrochemical behavior and electrochromic properties of PEDOS films in different electrolytes?pure BmimPF₆,aqueous emulsion and ACN system?were systematically investigated.The results showed that EDOS could be electropolymerized at low potential in aqueous emulsion?0.64 V,the polymerization potential in acetonitrile system was reported to be 0.95 V?,and the obtained PEDOS films retained 75.3%electroactivity after 5000 cycles.Kinetic studies showed that PEDOS had higher coloring efficiency?20 cm²/C?and contrast?25%?in BmimPF₆than in acetonitrile?19 cm²/C,22%?.2.Electrochemical polymerization of 3,4-propylenedioxylene?ProDOS?and its alkyl derivatives in ionic liquid system and electrochromic properties of polymer films.In order to overcome the defects of poor solubility of EDOS,the extended ring structure ProDOS and its alkyl side chain modified derivative?ProDOS-C₁ and ProDOS-C₄?were designed and synthesized,and the ionic liquid BmimPF₆ was used as the electrolyte system.The polymer films of PProDOS and its derivatives were prepared by electrochemical polymerization,and their electrochemical and electrochromic properties were systemically compared.The results showed that the alkyl modification improves the solubility and electrochemical properties of the monomer and polymer.With the increase of the alkyl chains,the initial oxidation potential of monomers showed a decreasing trend,and the electrochemical activity of polymer films in pure BmimPF₆ showed an increasing trend.Among them,PProDOS-C₄ retained 87%electrical activity after 5000 cycles and had high coloring efficiency?573 cm²/C?,and PProDOS-C₁ had excellent optical contrast?62%?,which was superior to its polythiophene,poly?3,4-propoxydioxythiophene??PProDOT?.3.Thepreparationandelectricalpropertiesof poly?3,4-ethylenedioxyselenophene?/poly?4-styrenesulfonate??PEDOS/PSS?aqueous dispersion and its free-standing film.The chemical oxidative polymerization in the aqueous emulsion can overcome the solubility of EDOS and its derivative monomers,and obtain a large number of PEDOS samples and flexible conductive films at one time.In this thesis,EDOS and five other analogues structures?EDOT,EOTT,EDTT,EOTS and EDTS?were designed and efficiently synthesized,and six kinds of PEDOTs/PSS aqueous dispersion were prepared by chemical oxidative polymerization in polystyrene sulfonic acid?PSS?aqueous emulsion.The flexible free-standing films which can be cut are obtained by drop-coating on the polypropylene?PP?substrate.The effects of structural evolution on the physicochemical properties and electrical conductivities of the polymers are systematically studied.The results showed that the color of the dispersion is gradually darkened when the ethylene ring is the same and the Se atom is substituted for the S atom.The conductivities of PEDOTs/PSS free-standing films substituted by S and Se elements are significantly reduced.The conductivity enhancement effect of DMSO secondary doping is applicable to PEDOTs/PSS films.