Preparation And Characterization Of Multicolor Electrochromic Materials Based On Thiophene And Triphenylamine Derivatives

Electrochromic material is known as one of the most valuable functional materials nowadays.The exploiture of excellentelectrochromic materials and the preparation of resultant electrochromic devices would promote the potential applications.As one of the important electrochromic materials,conducting polymers get more and more attentions because of their various species,easy preparation,controllable energy gap etc.Among conducting polymers,polythiophenes and polytriphenylamine derivatives are always the focus of research due to their easy preparation,apparent coloration,fast switching time,good stability and so on.We prepared a series of novel monomers based on thiophene and triphenylamine derivatives,including 1,4-di(thiophen-3-yl)benzene(DTB),N-phenylnaphthalen-2-amine(BNA),N-(4-(1H-pyrrol-1-yl)ph-enyl)-N-phenylnaph-thalen-2-amine(NAP)and N1,N4-bis(4(1H-pyrrol-1-yl)-phenyl)N1,N4-diphenyl-benzene-1,4-diamine(DPTPA).The resulting conducting polymer films were prepared electrochemically,and the polymer films were used to prepare electrochromic devices,their electrochromic properties were stuied.These monomers showed good electrochemical response,and their resultant polymers can be electrochemically synthesized,and the devices showed good electrochromic properties.Polymer PDTB has two colors of yellow and blue,then a copolymer film was successfully prepared from DTB and 3,4-ethylenedioxy-thiophene(EDOT).The copolymer film showed red,yellow,green and blue four colors,containing the three primary colors of red,green and blue.Furthermore,the copolymer film exhibits relatively fast switching time(0.8 s at 746 nm)and high optical contrast(high up to 59%).Cyclic voltammetry study reveals that the copolymer film has excellent stability,the redox curves only showed a little shrink after 500 cycles.PBNA film and PNAP film also can be electrochemically synthesized.PBNA film showed five different colors from light yellow to blue under different potentials.Besides,PBNA film has relatively fast switching time(0.9 s at 400 nm,2.4 s at 500 nm and 1.8 s at 1100 nm).PBNA film showed reasonable stability in CV test.PNAP film also showed five different colors from brown to dark blue,the switching time at 433 nm is 2.7 s and 2.0 s at 1100 nm.The CV test showed that PNAP film has reasonable stability too.PDPTPA film exhibited the most excellent electrochromic properties.The film displays six colors from blue to yellow under different potentials.PDPTPA film presented high optical contrast and fast switching time.Optical contrast at 410 nm is 20%and 52%at 617 nm,41%at 852 nm.The switching time is 1.3 s at 410 nm,1.4 s at 852 nm and 0.6 s at 617 nm.The stable curves in long time electrochromic switching and the little change in CV curves after 500 cycles indicate the goog stability.