Optical: systems and elements – Optical modulator – Light wave temporal modulation
Patent
1997-04-09
1999-12-21
Sugarman, Scott J.
Optical: systems and elements
Optical modulator
Light wave temporal modulation
359270, 359273, 25251931, 25251932, 429188, 427226, 4271263, G02F 115
Patent
active
06005705&
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to electrochromic thin-film systems and their components, especially those which are prepared by the sol-gel process.
2. Discussion of the Background
Large numbers of electrochromic thin-film systems are described in the literature for a variety of fields of application and in different combinations of individual components.
For the preparation of the functional oxide layers the methods described hitherto have predominantly been vacuum methods, such as thermal evaporation, sputtering or CVD, and also spray pyrolysis and electrochemical deposition methods. However, these processes are unsuitable and/or too cost-intensive for the production of homogeneous coatings with a large surface area. In recent years, some attempts have been made to produce such systems by sol-gel processes, since these processes are notable for a great scope variation and, owing to the avoidance of vacuum technology, by substantially lower costs for the production of homogeneous coatings of large surface area. However, the systems described in the literature to date are not yet entirely satisfactory.
In particular, in the case of electrochromic oxide layers, especially of tungsten oxides and molybdenum oxides, the fact that the oxides in a freshly prepared thin-film system are initially free from alkali metal ions means that these systems have to be operated for a relatively long period before, gradually, the desired insertion disequilibrium by incorporation of alkali metal ions from the electrolyte ion reserve. This leads to initial impairment of function.
SUMMARY OF THE INVENTION
It was therefore one object of the present invention to produce electrochromic oxide layers based on tungsten oxides and/or molybdenum oxides which are fully functional immediately after their production.
In accordance with a first aspect of the present invention it has surprisingly been found that in the case of known tungsten oxide and molybdenum oxide preparation processes some of the oxide can be converted by reaction with alkali metal salts, especially alkali metal hydroxides, into the corresponding alkali metal tungstate or, respectively, molybdate without any adverse effect on the electrochromic function or on the ability to process the layers. This considerably accelerates the establishment of a stable operating state. Given an appropriate reaction regime, the addition of the alkali metal ions also does not lead to adverse changes in the optical layer properties or in the sol properties.
Furthermore, a large number of types of electrolyte have been proposed to date for electrochromic systems. Liquid and purely organic polymer electrolytes, however, can be employed only to a limited extent owing to their limited ranges of operating temperature, while purely inorganic types are subject to similar restrictions owing to their low ion conductivity at room temperature. Polymeric electrolytes are provided by hot pressing, inorganic types usually by sputtering techniques, between the oxide electrode layers.
A second object of the present invention, accordingly, is to provide an electrolyte for electrochromic systems which even at room temperature exhibits a satisfactory ion conductivity, provides a broad range of operating temperature and can be provided in an advantageous and simple manner between the oxide electrode layers.
In accordance with a second aspect of the present invention it has surprisingly been found that novel organic-inorganic nanocomposite systems based on certain organically modified alkoxysilanes not only do not have the majority of disadvantages of the known electrolytes but also are distinguished by a level of ionic conductivity which is surprisingly high for such composites, and is sufficient even at room temperature for satisfactorily rapid electrochromic functions.
Finally, a third essential component of electrochromic thin-film systems is a noncolouring ion insertion layer. Noncolouring oxidic ion insertion layers (for protons or lithium ions) a
REFERENCES:
patent: 4236792 (1980-12-01), Bissar
patent: 5209871 (1993-05-01), Mason
patent: 5227043 (1993-07-01), Shakushiro et al.
Berni Anette
Judeinstein Patrick
Krug Herbert
Merl Norbert
Moses Anke
Burke Margaret
Institut fuer Neue Materialien Gemeinnuetzige GmbH
Sugarman Scott J.
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