Fast switching, high contrast multichromic polymers from alkyl-derivatized dithienylpyrrole and 3,4-ethylenedioxythiophene

Abstract

In this report we disclose the synthesis and characterization of optoelectronic properties of a novel conducting polymer based on 1-(2-ethyl-hexyl)-2,5-di-thiophen-2-yl-2,3-dihydro-1H-pyrrole, (SNS-HE). Additionally, copolymers based on SNS-HE and 3,4-ethylenedioxythiophene (EDOT) were electrochemically synthesized and characterized. Cyclic voltammetry, FTIR, spectroelectrochemistry analyses confirmed that the resulting polymers were true copolymers having distinct electrochromic properties from that of the parent homopolymers. Depending on the synthesis conditions, the SNS-HE based polymers exhibited optical band gaps ranging from 2.32 to 1.70 eV and the copolymers displayed multichromism within a wide range of the visible spectrum. The copolymers revealed shorter switching times (around 0.5 s) and higher optical contrast (around 36%). Our studies have shown that color of the copolymers could be easily tuned by controlled increase in copolymerization potential. Moreover, a prototype of the all solid state poly(SNS-HE-EDOT)/PEDOT complementary electrochromic device was fabricated in order to investigate the utilization of these polymers. These devices exhibited short switching times with reasonable open circuit memory under atmospheric conditions.