Variable light transmittance glass board functional as electrochromic cell

• US 4,801,195 A
• Filed: 12/19/1985
• Issued: 01/31/1989
• Est. Priority Date: 01/29/1985
• Status: Expired due to Fees

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Kawai, Mikio, Ura, Mikio, Miyagi, Harutoshi
• Primary Examiner(s): Thexton, Matthew A.
• Assistant Examiner(s): SCALZO, CATHERINE KILBY
• Application Number:
  US06/810,687
• Time in Patent Office: 1,139 Days
• Field of Search: 252/600 APS, 350/357, 423/419 R
• US Class Current: 359/275
• CPC Class Codes: G02F 1/1516 comprising organic material
• CPC Class Codes: G02F 1/1525 characterised by a particular ion transporting layer, e.g. electrolyte
• CPC Class Codes: G02F 2001/1502 complementary cell
• CPC Class Codes: G02F 2001/1517 Cyano complex compounds, e.g. Prussian blue

Abstract

The invention relates to a variable light transmittance glass board which is an electrochromic cell in principle and is comprised of oppositely arranged two transparent glass substrates each of which is laid with a transparent electrode film, first and second electrochromic layers formed on the two electrode films, respectively, by using tungsten trioxide for the first layer and Prussian blue for the second layer and an electrolyte liquid which fills up the space remaining between the two electrode films. The electrolyte liquid is a solution of a conventional supporting electrolyte such as lithium perchlorate in an organic polar solvent such as propylene carbonate. Durability of both electrochromic layers at elevated temperatures is greatly improved by adding 0.2-3.0 wt % of water to the organic polar solvent. By using one or two auxiliary electrode(s) comprising an electrochemically oxidizable and reducible material and being disposed in a marginal region of the space between the two glass substrates, it is possible to prevent the appearance of the glass board from being marred by partial decomposition of the electrolyte liquid at the initial reduction of one electrochromic layer. A polymer of a conjugated compound, e.g. polytriphenylamine, is very advantageous as the electrochemically active material in each auxiliary electrode.

Claims

1. A variable light transmittance glass board which is functional as an electrochromic cell and which comprises:

two transparent glass substrates each of which is laid with a transparent electrode film and which are arranged such that the two transparent electrode films are held opposite to and spaced from each other;

a first electrochromic layer which comprises tungsten trioxide and is formed on one of the two transparent electrode films;

a second electrochromic layer which comprises Prussian blue and is formed on the other of the two electrode films; and

an electrolyte liquid which fills up the space remaining between the two transparent electrode films, said electrolyte liquid being a solution of a supporting electrolyte in an organic polar solvent to which 0.2 to 3.0 wt% of water is added.

2. A variable transmittance glass board according to claim 1, wherein said supporting electrolyte is an alkali metal compound.

3. A variable transmittance glass board according to claim 2, wherein said supporting electrolyte is a lithium compound selected from the group consisting of LiClO₄, LiPF₆ and LiBF₄.

4. A variable transmittance glass board according to claim 2, wherein said organic polar solvent is selected from the group consisting of propylene carbonate, acetonitrile, dimethylformamide and °

-butyl lactone.

5. A variable transmittance glass board according to claim 1, further comprising an auxiliary electrode which is disposed in a marginal region of the space between said two transparent glass substrates so as to be in contact with said electrolyte liquid and comprises an electrochemically oxidizable and reducible polymer of a conjugated compound.

6. A variable transmittance glass board according to claim 5, wherein said polymer is selected from the group consisting of polyacetylene, polyphenylene, polytriphenylamine, polypyrrole, polyindole, polyazulene, polythiophene, polyfuran, polynaphthalene, polyaniline, polydiacetylene, polyphenylene sulfide, polyphenylene oxide and polyphenylenevinylene.

7. A variable transmittance glass board according to claim 5, wherein said auxiliary electrode further comprises an electroconductive inorganic material.

8. A variable transmittance glass board according to claim 7, wherein said electroconductive inorganic material is a powder, said auxiliary electrode further comprising a charge collector member which is embedded in a mixture comprising said polymer and said powder.

9. A variable transmittance glass board according to claim 5, wherein said auxiliary electrode further comprises a charge collector member on which said polymer is deposited.