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Counter Electrode for Electrochromic Display

IP.com Disclosure Number: IPCOM000062274D
Original Publication Date: 1986-Nov-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Jones, AS: AUTHOR

Abstract

In an electrochromic display using an aqueous solution of viologen as the electrochromic material, ruthenium dioxide is used as a counter electrode. The electrode is formed by screening a paste consisting of ruthenium dioxide and acrylic resin, followed by curing and treating in an RF plasma. It is known to use platinum black as a counter electrode material but ruthenium dioxide has been found to be superior, apart from lower cost, for the following reasons: (1) On long-term cyclic testing under full constant current write, potentiostatic erase conditions the electrode goes less negative than the equivalent platinum black electrode after the same amount of driving (i.e., it is less likely to be coated with viologen during the erase cycle and hence lose more surface area).

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Counter Electrode for Electrochromic Display

In an electrochromic display using an aqueous solution of viologen as the electrochromic material, ruthenium dioxide is used as a counter electrode. The electrode is formed by screening a paste consisting of ruthenium dioxide and acrylic resin, followed by curing and treating in an RF plasma. It is known to use platinum black as a counter electrode material but ruthenium dioxide has been found to be superior, apart from lower cost, for the following reasons: (1) On long-term cyclic testing under full constant current write, potentiostatic erase conditions the electrode goes less negative than the equivalent platinum black electrode after the same amount of driving (i.e., it is less likely to be coated with viologen during the erase cycle and hence lose more surface area). (2) The maximum excursion of the electrode potential between full write and full erase conditions is lower. (3) The adhesion for screened RuO2 on a titanium conductor is much better than that of the plated or screened platinum black. The preferred process is to screen a paste containing 65% by weight of RuO2 and the remainder of acrylic resin through a mesh onto a Ti/Au conductor pattern on a glass substrate. The screened paste is then cured at 170OEC for 35 minutes. Finally, the cured film is exposed to RF plasma in air for 10 minutes to increase its surface area by removing surface acylic resin.

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