Syntheses of novel fluorinated dibenzo[a,c]phenazine comprising polymers for electrochromic device applications

Abstract

In this study, two novel fluorinated dibenzo[a,c]phenazine derivatives, 2,7-bis(5-bromo-4-hexylthiophen-2-yl)-11-fluorodibenzo[a,c]phenazine (TFBPz) and 2,7-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-11-fluorodibenzo[a,c]phenazine (EFBPz), were synthesized by coupling fluorodibenzo[a,c]phenazine (FBPz) with electron rich 3-hexylthiophene and ethylene dioxythiophene (EDOT) units. The monomers were polymerized electrochemically and their electrochemical, spectroelectrochemical and electrochromic behaviors were studied. Then, PTFBPz and PEDOT comprising electrochromic device was constructed and reported. Comparing both polymers in terms of their redox potentials, as expected, PEFBPz showed a lower oxidation potential due to the insertion of an electron rich EDOT unit into the polymer chain, which increased the electron density significantly. EDOT comprising dibenzo[a,c]phenazine derivative PEFBPz exhibited a red shifted neutral state absorption with lower optical band gap values compared to those of PTFBPz. Furthermore, three novel D-A type dibenzo[a,c]phenazine comprising polymers (PBDT-TFBPz, PBDT-FBPz and PSi-TFBPz) were synthesized chemically and all polymers were investigated in terms of their electrochromic and physicochemical behaviors.