A novel 1,1′-bis[4-(5,6-dimethyl-1H-benzimidazole-1-yl)butyl]-4, 4′-bipyridinium dibromide (viologen) for a high contrast electrochromic device

Sydam, R and M, Deepa and Joshi, A G (2013) A novel 1,1′-bis[4-(5,6-dimethyl-1H-benzimidazole-1-yl)butyl]-4, 4′-bipyridinium dibromide (viologen) for a high contrast electrochromic device. Organic Electronics, 14 (4). pp. 1027-1036. ISSN 1566-1199

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A new electrochromic viologen, 1,1′-bis-[4-(5,6-dimethyl-1H- benzimidazole-1-yl)-butyl]-4,4′-bipyridinium dibromide (IBV) was synthesized by di-quaternization of 4,4′-bipyridyl using 1-(4-bromobutyl)-5,6-dimethyl-1H-benzimidazole. X-ray photoelectron spectroscopy confirmed the formation of the IBV (viologen) salt as distinct signals due to quaternary nitrogen and neutral nitrogen, and ionic-bonded bromide were identified. An electrochromic device encompassing a dicyanamide ionic liquid based gel polymeric electrolyte with high ionic conductivity, a thermal decomposition temperature above 200 °C, and a stable voltage window of ∼4 V with the IBV viologen dissolved therein, was constructed. IBV is a cathodically coloring organic electrochrome and the device underwent reversible transitions between transparent and deep blue hues; the color change was accompanied by an excellent optical contrast (30.5% at 605 nm), a remarkably high coloration efficiency of 725 cm2 C-1 at 605 nm and switching times of 2-3 s. Electrochemical impedance spectroscopy revealed an unusually low charge transfer resistance at the IBV salt/gel interface, which promotes charge propagation and is responsible for the intense coloration of the reduced radical cation state. The device was subjected to repetitive switching between the colored and bleached states and was found to incur almost no loss in redox activity, up to 1000 cycles, thus ratifying its suitability for electrochromic window/display applications

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IITH Creators:
IITH CreatorsORCiD
Item Type: Article
Additional Information: One of the authors, Rambabu Sydam acknowledges University Grants Commission for junior research fellowship.
Uncontrolled Keywords: Dicyanamide ionic liquid; Electrochromic device; Prussian blue; Viologen
Subjects: Chemistry
Divisions: Department of Chemistry
Depositing User: Team Library
Date Deposited: 15 Dec 2014 11:33
Last Modified: 18 Oct 2017 09:36
URI: http://raiith.iith.ac.in/id/eprint/1124
Publisher URL: https://doi.org/10.1016/j.orgel.2013.01.035
OA policy: http://www.sherpa.ac.uk/romeo/issn/1566-1199/
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