Research On The Preparation And Properties Of Electrochromic Of D-A Materials Based On [1,2,5]thiadiazolo[3,4-c]pyridine

Conducting polymers have been considered as promising materials due to their good electrochromic properties.These materials are used in many fields,such as electrochromic devices,sensors,solar cells,light emitting diodes,supercapacitor and so on.Compared with the 2,1,3-benzothiadiazole(BTD)unit,[1,2,5]thiadiazolo[3,4-c]pyridine(PT)heterocycle is a stronger acceptor due to the presence of the additional pyridine N-atoms.PT-containing compound have facile structural modification through introduce multifunction substituent to decrease the band gap,which present various electrochromic properties.Polythiophene and its derivatives have a good application prospect in organic and optoelectronic devices,because of its strong stability,high conductivity,tunable band-gap and electrochromic properities.In this paper,we synthesized a variety of monomers via coupling reaction and electrochemical polymerization,and studied their photoelectric properties.We have been successfully synthesized six novel D–A type monomers as well as their corresponding polymers by electropolymerization.For the investigation of their electrochemical and electrochromic properties,the polymers were characterized using cyclic voltammetry(C V),UV-vis spectroscopy,step profiling,and scanning electron microscopy(SEM).These results showed that they could realize the tunableness of the band gap and express different electrochromic properties due to the different substituents.Alkoxy thiophene has lower band gap and better electrochromic properties than alkyl thiophene,which further demonstrated that alkoxy thiophene has stronger electron-donating ability and more appropriate to produce the low band gap conjugated polymer materials.All polymers revealed good stability,high optical contrast,satisfactory coloration efficiency and fast response time.PEDOT-TP-BTD was successfully synthesized by electropolymerization.Among CPs,poly(3,4-ethylenedioxythiophene)(PEDO T)is considered to be a prospective supercapacitor electrode material due to its high conductivity(up to 500 S/cm.),fast charge/discharge ability,wide potential window,and good environmental stability.The capacitive behaviors and performances of PEDOT-TP-BTD were tested by galvanostatic charge-discharge,electrochemical impedance spectroscopy techniques and long-term cycle stability test.Via electrochemical investigation,PEDOT-TP-BTD electrode exhibits favor-able electrochemical stability,enhanced specific capacitance and specific energy.