JPS58216225A - Electrochromic display element - Google Patents

Abstract

PURPOSE:To obtain an ECD having stable performance by preventing the deterioration of a display electrode by using an electrolyte. CONSTITUTION:An ECD is constituted of a glass substrate 1, a transparent electrode 2 consisting of indium oxide, a display material of WO2, a counter electrode 4 of carbon, a net 5 for current collection, an electrolyte 6, an isolation and reflection plate of alumina, a rear case 8, a lead 9 for the display electrode, and a lead 10 for the counter electrode. The electrolyte 6 is prepd. by dissolving 0.3mol/l LiClO4 and 0.05mol/l SiF6 in propylene carbonate. It is extremely effective to add fluorocomplex salt to the electrolyte in order to inhibit the deterioration thereof. The electrolyte contg. silicon as a constituting element has effect of increasing quantity of electricity and increasing solubility as compared to the electrolyte contg. no silicon. M2(ZnF4), M(BF4), M3(SbF6), M2(GeF6), M(PF6) (M is one from Li, Na, K) have the similar effect as the fluorocomplex salt.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrochromic display element (hereinafter abbreviated as ECD) using an electrochromic substance as a display material.
Regarding.

In ECD, an electrochromic material is used as a display electrode, and an electrolyte exists between it and a counter electrode, and when a voltage is applied between the display electrode and the counter electrode, the display material is electrochemically oxidized or This is an element whose display principle is based on the phenomenon of color development through reduction.

Conventionally, in this type of display element, tananium oxide (Pagesten oxide) is used as the display material, and lithium perchlorate dissolved in propylene carbonate is used as the electrolytic solution.

Although an element with such a configuration is characterized by a fast response speed, it has the disadvantage that its characteristics deteriorate significantly during storage, and it deteriorates in a short period of time, especially at high temperatures, and the coloring density becomes lighter at the same driving voltage. . This occurs because the characteristics of the display material (tungsten oxide) constituting the display electrode deteriorate during storage.

The present invention prevents the deterioration of the ECDO display electrode as described above by using an appropriate electrolyte, and
The aim is to extend the lifespan of the

Here, to explain the electrolytic solution used in the present invention, various salts are added (dissolved and suspended) based on the electrolytic solution in which lithium perchlorate is dissolved in, for example, propylene carbonate as an organic solvent. Various fluoro complex salts such as tetrafluoro complex salts and hexafluoro complex salts were effective in preventing deterioration.This is thought to be because fluorine ions gradually released from fluoro complex salts prevent deterioration of tungsten oxide. A detailed explanation of the present invention in which a fluoro complex point is added will be described below.

(Example 1) The figure shows an ECD in this example, where 1 is a glass substrate,
2 is a transparent electrode made of indium oxide, 3 is a display material made of wO3, 4 is a counter electrode made of carbon, 5 is a current collecting net, 6 is an electrolytic solution, 7 is an isolation reflector made of alumina, 8 is a back case , 9 is a display electrode lead, and 10 is a counter electrode lead.

The electrolyte is propylene carbonate and lithium perchlorate (
LiCAO4) 0.3 mail, /n, ,
Lithium hexafluorosilicate (Li25iF6) o
, o5m□fl /12 was used.

(Example 2) L 1Cj24 in propylene carbonate as an electrolyte
(Example 3) LiCu040 in propylene carbonate as an electrolyte
-37H (J/fl dissolved and saturated with K2TaF7) was used, and the other procedures were the same as in Example 1.

(Conventional example) For comparison, propylene carbonate L was used as the electrolyte.
A prototype ECD was prepared in the same manner as in Example 1 except that only 1CQOa O-3rnoQ / was dissolved.

For each element prototyped as above, the display limit 9 is set to negative,
When an electric current and pressure are applied for 1 second at 1■ with the counter electrode 1o positive, an amount of electricity flows compared to the coloring density, but
The change in the amount of electricity (coloring density) is compared to the initial value at 0°C.
The deterioration status was investigated by measuring the values after storage for 3 and 20 days. The results are shown in the table below.

As is clear from a comparison between the conventional example shown in the table on page 5 and the example of the present invention, the addition of a fluoro complex salt is extremely effective in suppressing deterioration of the electrolytic solution. Among the fluoro complex salts, those containing silicon as a constituent element are
It has the effect of increasing the amount of electricity compared to the case without additives, and also has the characteristic of being easy to use due to its high solubility. Those containing aluminum as a constituent element have a characteristic that, compared to other materials, there is less tendency for oxides to precipitate on the top of the display.

In addition to the above, M2 [znF4] is a fluoro complex salt.

MCBF41. M3[SbF6':], M2[Ge
F6'], M[PF61, etc. (M is L 1 +
, Na + K. ) has a similar effect.

As described above, the present invention prevents deterioration of the electrolytic solution and provides an ECD with stable performance, and has great industrial value.

[Brief explanation of the drawing]

The figure is a cross-sectional view of an electrochromic display element according to the present invention. 6 pages...Glass substrate, 3...Display material, 4.
...Counter electrode, 6... Electrolyte.

Claims (1)

[Claims] A display electrode made of an electrochromic material containing tungsten oxide as a main component is opposed to a counter electrode via an electrolyte.
An electrochromic display element characterized in that the electrolytic solution is composed of an electrolytic solution in which a fluoro complex salt is added to an organic solvent in which lithium perchlorate is dissolved.