A Low Band Gap Benzimidazole Derivative and Its Copolymer with 3,4-Ethylenedioxythiophene for Electrochemical Studies

Abstract

A novel monomer; 2-(3-nitrophenyl)-4,7-di(thiophen-2-yl)-1H-benzo [d]imidazole) (BIMN) was used for electrochemical copolymerization with 3,4-ethylenedioxythiophene (EDOT). Polymerization was achieved in acetonitrile (ACN)/dichloromethane (DCM) (1:1, 1:3 and 1:5, molar ratios) solution containing sodium perchlorate (NaClO 4 ) and lithium perchlorate (LiClO 4 ) mixture as the supporting electrolyte on an ITO electrode. The chemical structures of monomer and copolymers were characterized by nuclear magnetic resonance ( 1 H NMR) and scanning electron microscopy (SEM). The optical and electrochromic properties were investigated by UV-vis spectrophotometer and cyclic voltammetry, respectively. Combination of BIMN and EDOT provides lower oxidation potential, lower bandgap and higher optical contrast.

Low band-gap diketopyrrolopyrrole-containing polymers for near infrared electrochromic and photovoltaic applications

“…Due to the stronger electron‐donating ability of EDOT monomer, the HOMO of P1 and P2 is much higher compared with reported DPP polymers with thiophene or fused thiophene as the co‐monomer . Such a high‐lying HOMO orbital, arising from the electron‐rich nature of EDOT moiety, is rather favorable for EC applications as the onset and operating voltage of the EC device would be significantly lowered . A summary of the data is available in Table .…”

The role of structural and electronic factors in shaping the ambipolar properties of donor–acceptor polymers of thiophene and benzothiadiazole

“…16 Some D-A polymers exhibited remarkable properties such as broad and strong absorption, narrow band gap, fast and reversible colour switching, high conductivity and high stability during oxidative and reductive doping processes. [17][18][19][20] These traits led them to nd application in modern electronics like photovoltaics, [21][22][23] organic eld effect transistors, 24 and electrochromics. 18,[25][26][27] The benzothiadiazole (BT) molecule is one of the richest electron acceptor units used to tailor the position of LUMO energy level in D-A type polymers.…”

Synthesis and characterization of new thiophene--benzimidazole-based electrochromes

“…It is obvious that the benzimidazole unit can be substituted by different alkyl or cyclic-aromatic units and each resulting benzimidazole shows different electro-optical properties, even if they are coupled with the same donor. 7,35,37,40 Thus, due to this main advantage, use of benzimidazole acceptors in donor-acceptor type of polymers will be continued in future studies.…”