Electrochromic device response controlled by an in situ polymerized ionic liquid based gel electrolyte
IR@NPL: CSIR-National Physical Laboratory, New Delhi
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| Title |
Electrochromic device response controlled by an in situ polymerized ionic liquid based gel electrolyte
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| Creator |
Sydam, Rambabu
Deepa, Melepurath Srivastava, A. K. |
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| Subject |
Chemistry
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| Description |
Polymer electrolytes were synthesized by two different approaches and applied to electrochromic devices based on electrodeposited tungsten oxide (WO3) or poly(3,4-ethylenedioxythiophene) (PEDOT) films as the cathode, and a Prussian blue (PB) film as the anode. The first method involved the entrapping of an ionic liquid in a polymer host (poly(methylmethacrylate) or PMMA) and the second approach relied on the in situ thermal polymerization of methylmethacrylate (MMA) in the hydrophobic ionic liquid, yielding a solidified transparent gel. The effect of in situ solid polymer electrolyte formation on device performance characteristics was realized in terms of a larger coloration efficiency of 119 cm(2) C-1 (lambda = 550 nm) achieved for the WO3-PB (MMA) device, as compared to a value of 54 cm(2) C-1 obtained for the WO3-PB (PMMA) device. Similar enhancements in electrochromic coloring efficiency, reflectance contrast, and faster switching kinetics were obtained for the PEDOT-PB (MMA) device. The strategy of introducing an electrolyte to the electrochromic device in a liquid state and then subjecting the same to gradual polymerization allows greater accessibility of the electrolyte ions to the active sites on the electrochromic electrodes and superior interfacial contact. As a consequence, larger optical contrast and faster kinetics are achieved in the MMA based devices. While PEDOT films were amorphous, PB films were semi-crystalline but only in the case of WO3; the hexagonal structure of WO3, equipped with three/four/six-coordinated voids was found to affect bleaching kinetics favorably. The performance of PMMA based electrolyte is limited by high resistance at the electrode-electrolyte interface, and a smaller number of ions available for oxidation and reduction. Large area (similar to 10 cm x 4 cm) devices were also fabricated using this simple wet chemistry method and their ability to color uniformly without any pinholes was demonstrated.
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| Publisher |
Royal Society of Chemistry
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| Date |
2012
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| Type |
Article
PeerReviewed |
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| Format |
application/pdf
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| Identifier |
http://npl.csircentral.net/3602/1/Electrochromic%20device%20response%20controlled.pdf
Sydam, Rambabu and Deepa, Melepurath and Srivastava, A. K. (2012) Electrochromic device response controlled by an in situ polymerized ionic liquid based gel electrolyte. RSC Advances , 2 (24). pp. 9011-9021. ISSN 2046-2069 |
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| Relation |
http://npl.csircentral.net/3602/
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