A new electrochromic copolymer composed of 4,7-di(thiophen-2-yl)benzo[c] [1,2,5] thiadiazole and 3,4-ethylenedioxythiophene

Abstract

A new electrochromic copolymer based on 4,7-di(thiophen-2-yl)benzo[c] [ 1 , 2 , 5 ]thiadiazole and 3,4-ethylenedioxythiophene was successfully obtained via the electrochemical polymerization method in the medium of electrolyte solution, which consists of 0.1 M tetrabutylammonium hexafluorophosphate and dichloromethane. In order to compare the electrochemical and chemical properties of the copolymer, the benzothiodiazole derivative and 3,4-ethylenedioxythiophene (EDOT) monomers, which are parts of the copolymer, are electrochemically polymerized, separately in the same environment and concentration with the copolymer. Poly(4,7-di(thiophen-2-yl)benzo[c][ 1 , 2 , 5 ]thiadiazole) (P(TBT)) and poly(3,4-ethylenedioxythiophene) (PEDOT) polymers were obtained. Before starting the electrochemical synthesis, the initial oxidation potentials of the monomers that form the copolymer were compared via the cyclic voltammeter method in this solvent electrolyte medium. Then, electrochemical and spectroelectrochemical characterizations of electrochemically synthesized polymers and copolymers were performed. New copolymer shows metallic blue and centaury blue in its neutral and oxidized states, respectively with a low band gap of 1.32 eV. Moreover, the copolymer has a 59% optical contrast and high coloration efficiency (324 cm 2 C −1 ) at 585 nm with a switching time of 2.2 s.

Crystals of 4,7-Di-2-thienyl-2,1,3-benzothiadiazole and Its Derivative with Terminal Trimethylsilyl Substituents: Synthesis, Growth, Structure, and Optical-Fluorescent Properties

“…T-BTD is a donor-acceptor molecule with a ground state energy level of −5.4 to −5.3 eV, and the energy transition from the ground to the nearest excited state is ΔE = 2.4-2.7 eV [8,13,14]. This compound is used as an individual substance or as a monomeric unit to obtain lowbandgap conjugated polymers for photovoltaics [1,[15][16][17][18][19]. A supramolecular polymer composition called "host-guest" has been reported, where T-BTD molecules are organized into highly ordered structures within a polymer matrix, leading to reduced fluorescence quenching and significantly enhancing solid-state emission efficiency [20].…”