Electrochromic properties of a polydithienylpyrrole derivative with N-phenyl pyrrole subunit

Abstract

In this report, a new N-phenyl typed 2,5-dithienyl pyrrole compound bearing pyrrole unit was successfully synthesized and its conjugated homopolymer, poly(1-(4-(1H-pyrrol-1-yl)phenyl)-2,5-di(thiophen-2-yl)-1H-pyrrole) (P(SNS-Ph-Pyr)), was obtained in the medium of 0.1 M TBAPF6/DCM via electroanalytical methods. Cyclic voltammetry and FTIR studies proved that monomer SNS-Ph-Pyr was synthesized and polymerized electrochemically and its corresponding polymer film, P(SNS-Ph-Pyr)) has a well reversible redox peaks at about 0.70/0.50 V vs. Ag/AgCl reference electrode in monomer free solution with a long term reversible redox behavior. The in situ UV–visible spectroelectrochemical studies of polymer film exhibited that electrochromic P(SNS-Ph-Pyr)) film had a color transition between yellow (at reduced state (0.0 V)) to grayish blue (at oxidized state (1.0 V)) with a intermediate color (green at 0.70 V). Moreover, electrochromic switching studies displayed that polymer film (coated with a thickness of 100 mC/cm2) had average optical contrast values (15.6% (383 nm), 19.5% (650 nm) and 41.7% (900 nm) but high coloration efficiency values (220 cm2/C (383 nm), 264 cm2/C (650 nm) and 384 cm2/C (900 nm).