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Electrochromic Materials

IP.com Disclosure Number: IPCOM000083090D
Original Publication Date: 1975-Mar-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Chang, IF: AUTHOR [+2]

Abstract

It is known that, generally, an electrochromic effect in solid materials is due to color center absorption whereas in liquids, it is due to color absorbing species produced by electrochemical reaction, or chemical reaction triggered by electrochemical reaction. The electrochromical effect is generally more efficient in liquids. For present purposes, efficiency is defined by the amount of absorption produced by one electron volt.

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Electrochromic Materials

It is known that, generally, an electrochromic effect in solid materials is due to color center absorption whereas in liquids, it is due to color absorbing species produced by electrochemical reaction, or chemical reaction triggered by electrochemical reaction. The electrochromical effect is generally more efficient in liquids. For present purposes, efficiency is defined by the amount of absorption produced by one electron volt.

Several electrochromic material systems are known. For example, an organic electrochromic liquid, which shows good sensitivity, is known. However, the material synthesis of this electrochromic liquid is complicated, and thus the material is quite expensive. Inorganic systems are likewise known. For example, in one system, solid WO(3) is mixed in an acidic gel solution. This system exhibits slow writing and erasing speeds.

In another system, oxyanion of tungsten or molybdinum are used. The solution is acitified by HCl. However, in this latter electrochromic liquid, the optical density change is limited, and is too sensitive to the PH value of the liquid. It is known, that the lower the PH value, the better the sensitivity. However, at low PH values, the liquid tends to show color absorption, exhibit precipitation and even result in gellation. In gel form, the electrochromic color bleaches extremely slow.

In Volume 17, Number 4, at page 1050, of the September 1974 IBM Technical Disclosure Bulletin, there is described an electrochromic material of sodium tungstate com...