The Synthesis And Electrochromic Study Of Soluble Copolymers Based On Triphenylamine,Quinoxaline And Benzotriazole

Organic conductive polymer(CP)has been available for decades,in the past few decades,people‘s research on it have been rising steadily.The reason was that CP has not only the optoelectronic properties of metal and inorganic semiconductor,but also has the flexible mechanical properties and processability of the polymer.And it can be used in many fields such as energy-saving materials,low-energy displays,rear mirrors for automobiles,electrochromic electronic skin,bulk heterojunction solar cells,semiconducting polymer dots(Pdots)and so on.At present,the study of CP has turn to its practical applications gradually,but we still believe that the research and develop of polymer with novel structure and unique properties is necessary.As we known that the production of multipurpose materials relies on newly designed structures mostly,especially the design of D-A style molecules.The donor–acceptor approach,one of the most plausible ways for the construction of low band gap systems,is confirmed by assembling an electron rich unit with a high HOMO level and an electron deficient unit with a low LUMO level in the structure.Besides obtaining low band gap polymers,the D–A approach is also useful in producing polymers with improved optical,mechanical and electronic properties.In this study,ten original soluble copolymers were synthesized by the method of chemical polymerization with triphenylamine,quinoxaline and benzotriazole as the precursors.There are PTTPA,PCTPA,PTDPQ,PTDPP,PTZQ-1,PTZQ-2,PTZQ-3,PBZQ-1,PBZQ-2 and PBZQ-3.The detailedly study of them shown that PTTPA(D-A type)has good thermal stability,low optical band gap(1.69 eV),high optical contrast and fast response time in NIR region.The introduction of N atom in PTDPP can not only enhance the electron-withdrawing ability of pyrido [3,4-b] pyrazine,but also improve the electrochromic properties of the copolymer.We can navigate the photoelectrical properties of copolymer by the means of changing the molar ratio of its components.The response time of PTZQ-1,PTZQ-2 and PTZQ-3 in the visible region were all less than 0.75 s.The optical contrast and response time of PTZQ-3 at 1670 nm were 49.2% and 184.24 cm2 · C-1,respectively.Among them the color changes of PBZQ-2 covers red,green and blue(RGB)and that of PBZQ-3 undergoes a black transition state,which is a very important electrochromic feature.The band gap of PBZQ-1,PBZQ-2 and PBZQ-3 were 2.10 eV,2.11 eV and 2.03 eV.This medium band gap can find applications in photovoltaic cells especially in highly efficient tandem cells.