JPS61252535A - Electrochromic display element - Google Patents

Abstract

PURPOSE:To improve the response speed and display life of an electrochromic display element by providing a soln. or electrolyte packed between substrates, which soln. and electrolyte contain a supporting electrolyte and solvent and are further added with an electrolytically polymerizable monomer. CONSTITUTION:Glass or plastics is used for the substrates 1, 4 and a compd. such as In2O3, SnO2, or In2O3-SnO2 is used for a display electrode 2. The same compd. or metal is used for a counter electrode 5. An EC material, supporting electrolyte and solvent to which the electrolytically polymerizable monomer is added are used for a displayable material 7. The dye of the styrile compd. expressed by the formula is used for the EC material. Tetrabutyl ammonium perchlorate is used for the supporting electrolyte and acetonitrile is used for the solvent. Pyrrole is used as the electrolytically polymerizable monomer at 1mol/l concn. The above-mentioned element has the display characteristics that the coloration density is higher by about 10% in light absorptivity and that the time to the satd. density is about 2 times shorter as compared with the element contg. no electrolytically polymerizable monomer. The response speed of the display characteristics and the display life are thus improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electrochromic display element that can be used as various display elements for watches, home appliances, guidance displays, information equipment, and the like.

Compared to conventional liquid crystal displays, electrochromic displays have no viewing angle dependence, and their colors are bright and clear.

Electrochromic (EC) materials used include metal oxides such as the inorganic compound WO3, and organic compounds such as viologen derivatives.

WO3 is formed into a thin film by vapor deposition or the like on a transparent electrode, and an electrolytic solution, a dielectric film, etc. are provided between the counter electrodes to form an element.

In the case of viologen derivatives, they may be used in a solution form dissolved in an aqueous solution, or they may be blended or complexed with a polymer to form a solid film.

Problems to be Solved by the Invention Practical problems with these devices include display life and response speed. As the electrode material, engineering n2o3. In203-SnO
Transparent electrode such as SnO, especially counter electrode material 2$
2 include platinum, gold, carbon, iron complexes, transition metal oxides [e.g. WO3), transition metal hydroxides (e.g. Nt(01(
)2) etc. are used. What is required of the counter electrode material is that it must not only be stable against electrolytes, but also be able to reversibly supply the same amount of charge as the redox reaction charge on the display electrode side. be. In order to speed up the supply and reception of charge to the opposite electrode, the surface area of the opposite electrode is generally increased to increase the response speed. Also,
In terms of display life, the potential of the counter electrode changes with respect to the driving time, and the electrode material elutes due to electrochemical reactions, deteriorating the characteristics.

Therefore, an object of the present invention is to increase the response speed and display life of an electrochromic display element by increasing the speed of charge transfer between the display electrode and the counter electrode and improving the reversibility during the redox reaction of the EC material. It is about making improvements.

Means for Solving the Problems The present invention achieves the above objects, and consists of a display electrode provided on either one of two substrates, at least one of which is transparent; A counter electrode provided on the other substrate facing the display electrode, and a solution or electrolyte filled between the substrates, the solution or electrolyte containing at least a supporting electrolyte and a solvent, and further containing an electrolytically polymerizable monomer. The object of the present invention is to provide an electrochromic display element characterized by the addition of

Function The present invention speeds up the charge transfer rate of the redox reaction of the EC material at the display electrode and counter electrode and improves the reversibility by adding an electrolytically polymerizable monomer to the solution or electrolyte of the electrochromic display element. be able to. The electrolytically polymerizable monomers of the present invention include those of oxidative polymerization type and reductive polymerization type, and for the former, those having an amino group or hydroxyl group in the benzene ring such as aniline and phenol, and heterogeneous monomers such as virol and thionoene. Dipenzo crown ether and the like are suitable as other types having a ring. On the other hand, for the latter, those having a vinyl group such as vinylpyridine are preferred.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cross-sectional view of an electrochromic display element in one embodiment of the present invention. 1 and 4 in the figure are substrates, which are made of glass or plastic.

2 is the display pole, engineering n2o3, 5n02. In2o3-8
An n02 study compound is used. 5 is the opposite pole, n203°5no2. Engineering n203-8no2 compounds or metals are used. 7 is a displayable substance, and 8 is a sealing material.

In addition to the EC material, the supporting electrolyte, and the solvent, an electrolytically polymerized monomer is added to the displayable substance 7 in this example.

A dye of a styryl-like compound such as Shimezu was used as the EC material, tetrabutylammonium perchlorate was used as the supporting electrolyte, and acetonitrile was used as the solvent. The concentrations are 0.03° and sM/l, respectively.

As the electrolytically polymerizable monomer, virol was used, and 1M
It was included at a concentration of ot/l.

When the display characteristics of this device were measured, it was found that the color density was lower than that of the device without the addition of electropolymerized additives.
(550 nm), the concentration was 10% higher and the time to reach saturation concentration was twice as fast. The decoloring speed was also about twice as fast. The reason why the response speed becomes faster is thought to be because the electric resistance of the stain electrolyte becomes smaller apparently by including the monomer in the electrolyte.

As a second example, thiophene which is oxidatively polymerizable in the same way as the electrolytically polymerizable monomer of the previous example is used.

When the display characteristics of aniline were measured using the display element shown in FIG. 1, a similar improvement in response speed was observed.

Virol had the best effect, followed by thiophene and aniline.

As a third example, using the same EC material as in Example 1,
Vinyl pyridine, which undergoes a reductive polymerization reaction, was added as an electrolytically polymerizable monomer in an amount of 0.1 mot/.

A continuous color display life test was conducted at 60C on an element that did not contain an electrolytically polymerizable monomer and an element that did contain the electrolytically polymerizable monomer, and the lifespan of the display element that did not contain an electrolytically polymerizable monomer was approximately 2000 hours.
However, it was confirmed that the concentration was 3000 I (or more).The evaluation at the end of life was set as so% of the initial concentration.The applied voltage was 1.3 V DC between display electrode 2 and counter electrode 6. did.

In the final state of deterioration, no coloring phenomenon occurs even if a voltage is applied.

A cross-sectional view of the display element in the fourth embodiment is shown in FIG. WO is deposited on the display electrode 2 provided on the substrate 1 by vapor deposition.
Using an EC membrane 3 such as 2 membranes, propylene carbonate was used as the solvent as the electrolytic solution 9, L t CtO4 was dissolved as the supporting electrolyte at a concentration of 1 mo17t, and thiophene was dissolved as the electropolymerizable monomer at a concentration of 0.55 mo/17t.
It was added at a concentration of 1. When the characteristics as a display element were measured, it was confirmed that the response speed was improved by 1.6 times and the number of repetitions of color development and fading was improved by about 2 times.

When such an element is allowed to develop color continuously for 100 hours or more, a polymer film (polythiophene film) 6 as shown in the figure is deposited on the counter electrode 6. By forming the polymer film 6 such as this polythiophene film, the response speed and display life are further improved.

The response speed becomes faster when the EC material or solution solution component and the transparent electrode (I
n2O3,5no2. The charge transfer rate with ITo) is also faster when using a polymer membrane, and the inclusion of monomers in the electrolyte reduces the apparent electrical resistance of the electrolyte. It seems to be for a reason.

In addition, by forming a polymer film, the surface of the stain electrode is stabilized, and corrosion of the display electrode 2 and counter electrode 5 can be prevented. By using the reaction as a reverse reaction, irreversible chemical reactions can be reduced and display life can be improved.

Effects of the Invention In short, the present invention provides two substrates, at least one of which is transparent, with a display electrode and a counter electrode facing each other, a solution or an electrolytic solution is filled between the substrates, and this solution or electrolytic solution provides at least a support layer. The present invention provides an electrochromic display element characterized by containing an electrolyte and a solvent and further adding an electrolytically polymerizable monomer, which can improve the response speed of display characteristics and the display life.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views of an electrochromic display element according to an embodiment of the present invention. 1...Substrate, 2...Display electrode, 3...
...EC film (WO2 film), 4...substrate, 6.
... Counter electrode, 6 ... Polymer film (polythiophene film), 7 ... Displayable substance, 8 ...
Sealing material, 9... Electrolyte solution. Name of agent: Patent attorney Toshio Nakao and one other person Figure 1 Figure 2

Claims (3)

[Claims] (1) A display electrode provided on one of two substrates, at least one of which is transparent, a counter electrode provided on the other substrate facing the display electrode, and a solution filled between the substrates, or An electrochromic display element comprising an electrolytic solution, wherein the solution or electrolytic solution contains at least a supporting electrolyte and a solvent, and further contains an electrolytically polymerizable monomer. (2) The electrochromic display element according to claim 1, wherein the electrolytically polymerizable monomer undergoes an oxidative polymerization reaction. (3) The electrochromic display element according to claim 1, wherein the electrolytically polymerizable monomer undergoes a reductive polymerization reaction.