Sydam, Rambabu and Deepa, Melepurath and Joshi, Amish 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. pp. 1027-1036. ISSN 1566-1199

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Abstract

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 degrees C, and a stable voltage window of similar to 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 cm(2) 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.

Item Type:	Article
Additional Information:	Copyright for this article belongs to M/s Elsevier.
Subjects:	Materials Science Applied Physics/Condensed Matter
Divisions:	UNSPECIFIED
Depositing User:	Users 27 not found.
Date Deposited:	28 May 2020 10:26
Last Modified:	28 May 2020 10:26
URI:	http://npl.csircentral.net/id/eprint/2969

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