JPS6240431A - Electrochromic element - Google Patents

Abstract

PURPOSE:To obtain the titled element (ECD) having a high memory and an excellent speed, life (duration) by using p-i-n type structure to an intermediate insulating layer of whole solid-state type thin film laminated ECD element. CONSTITUTION:The titled element is ocnstituted fundamentally of a transparent substrate 1, the 1st electrode 2 composed of a transparent electroconductive film, an electrochromic layer 3 of an oxidative coloring layer, an intermediate insulating layer 4, the 2nd electrochromic layer of a reductive coloring layer and the 2nd electrode 6 composed of an electroconductive film by laminating the prescribed layers in order. Thus, the intermediate insulating layer 4 is composed of three layers composed of a n-type layer 41, an i-type layer 42 and a p-type layer 43. For example, the titled layer is prepared by laminating the transparent substrate 1 made of a glass plate, the 1st transparent electrode 2 made of ITO, the oxidative coloring electrochromic layer 3 made of WO3, and intermediate insulating layer 4, the reductive coloring electrochromic layer 5 made of an iridium oxide and the 2nd transparent electrode 6 made of ITO in order. The intermediate layer 4 is constituted of the three layers comprising the layer 41 composed of Ta2O3, the layer 42 composed of SiO2, and the layer 43 composed of the Cr2O3 thin film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an all-solid thin film stacked electrochromic device (hereinafter abbreviated as ECD).

[Background of the invention]

A change in light absorption caused by induction of a reversible electrochemical reaction (oxidation/reduction reaction) by an electrical signal is called an electrochromic phenomenon, and a display element using this phenomenon is called an electrochromic display element (ECD).

ECDs are broadly classified into liquid type and solid type, and are expected to be applied to segment displays, matrix displays, optical shutters, aperture mechanisms, etc.

FIG. 2 shows an example of a conventional structure of a solid thin film stacked type ECD.

This device consists of a transparent substrate 1, a first electrode 2 made of a transparent 4-electrode film, and an electrochromic layer 3 which is an oxidized coloring layer.
, an intermediate insulating layer 4, a second electrochromic layer 5 which is a reduction coloring layer, and a second electrode 6 which is a conductive film are successively laminated.

In the above structure, the substrate 1 is generally formed of a glass plate, but this is not limited to a glass plate, and may be any transparent plate such as a plastic plate or an acrylic plate! (9) Regarding its position, it may be placed above the second electrode 6 instead of under the first electrode 2, or it may be provided on both sides depending on the purpose (for example, for the purpose of serving as a protective cover). . However, depending on these cases, it is necessary to make the second electrode 6 and the transparent conductive film, and also to make the electrodes on both sides transparent conductive films.

Transparent F for both electrodes! ! If it is used as a pole, a transparent element can be created.

The insulating layer 4 is not limited to dielectric material, but may also be made of solid electrolyte or the like.

An electrochromic element with such a structure has a first
T! By applying a voltage between the electrode 2 and the second electrode 6, an electrochemical reaction occurs, resulting in coloring and decoloring. It is generally said that this coloring mechanism is based on the formation of bronze by double injection of protons and electrons into the electrochromic layer 3, for example. For example, when using wo,1 as an electrochromic substance, the following (1)
The oxidation-reduction reaction expressed by the formula occurs, resulting in color.

Kabuto + xH++ xe-≠HxWOs (1
) According to formula (1), tungsten bronze HxWo
3. The color is formed and colored, but if the applied voltage is reversed at this point, the color disappears. In an electrochromic device, such a reaction of formula (1) is caused by proton ribs being supplied by the insulation 1- inside the device and causing coloration.

In the above-mentioned electrochromic element, the electrochromic layer 5, which is the anode-side coloring layer, is conventionally formed of a P-type transition metal oxide such as iridium oxide (IrO) by a reactive sputtering method or an anodic oxide film method.

The insulating layer 4 is a layer that acts as an electrolyte, blocking the injection of electrons from the electrode and allowing ions to pass through, but this blocking cannot be sufficiently performed with only one layer such as t'-Ta205 as in the past. However, it had the disadvantage of reducing the response speed and lifespan of the device.

[Purpose of the invention]

The purpose of the present invention is to improve an all-solid-state thin film stacked electrochromic device (ECD), and in particular to improve memory display quality and
[Summary of the Invention] The present invention is characterized by the above-mentioned all-solid-state thin film laminated electronic device. In the chromic element, the above intermediate insulating layer that performs proton donation and electron blocking is
-1-n three-layer laminated structure.

The reason for the three-layer structure of the intermediate insulating layer and p-1-n is as follows.

As mentioned above, the coloring and decoloring of ECD is performed by double injection of ribs and electrons on the cathode side to produce WO3+ xI (++
This reaction occurs as follows: x@--+ HxWO5 (e: 1 [child)]. As a compensatory reaction (oxidation) for this, on the anode side I r Oy + Z OH''' + Zh -) Ir
It is thought that the following reaction occurs: ey (OH), (2) (h: hole).

Furthermore, in equations (1) and (2), H” + o, which is involved in coloring and decoloring.
The H- source is adsorbed water contained within the element.

Therefore, for example, in order to improve the response of the element,
H+ and electron mobility on the 3 side, and OH- and hole mobility on the Ir0X side. All you have to do is raise it.

The meter and OH- are determined by the H2O dragon of the element, and the response is H”
, OH- and the corresponding electron/hole mobility - depends on the density of states. ECD of decomposition liquid Taigu
When considering this, the intermediate insulating layer is completely electronically blocked. However, the type of EC of the present invention is considered to be electronic to some extent. Therefore, as described above, the response is improved by making the WO3 type n-type, the IrOx side p-type, and the middle part between them to be l-type so that the junction is connected.

[Embodiments of the invention]

Hereinafter, the present invention will be explained with reference to examples. FIG. 1 shows an example of the structure of an electrochromic device according to the present invention. The electrochromic device shown in FIG. 1 is basically the same as the one shown in FIG. , an intermediate insulating layer 4, a second electrochromic layer which is a reduction coloring layer, and a second electrode 6 which is a conductive film are successively laminated.

In the present invention, the intermediate insulating layer 4 includes an n-type layer 41 and an i
It is composed of three layers: a type 7!42 and a p-type layer 43.

[Example 1] A transparent substrate 1 made of glass, a first transparent electrode [2] made of ITO
, oxidation coloring side electrochromic layer 3 made of WO3
, an intermediate insulating layer 4, a reduction coloring side electrochromic layer 5 such as iridium oxide (IrOx film), and ITO.
An electrochromic device was prepared by laminating the electrode 6 with a second transparent material.

The intermediate insulating layer 4 is a layer 41 made of Ta2O3, S r
A layer 42 made of 02, a layer 430 made of a Cr2O3 thin film
It has a three-layer structure.

In producing the above device, electrodes 2 and 6 were produced by a reactive RF ion blating method, layers 3 and 4 by an electron beam evaporation method, and layer 5 by a reactive starching method.

The film thickness was as follows.

Transparent electrode 2: 100OX Electrochromic jt53: 4000i Intermediate insulating layer 4 41: 300X 42: 300X 43: 3001 Electrochromic layer 5 near 00X Electrode 6: 100OX T of layer 4
It can be determined from the thermoelectromotive force signal that tL205 is n-type and Cr2O3 is p-type, and S t O2 is ~
With a conductivity of 1O-14s-crn-1, it can be said to be approximately i-type.

The coloring/decoloring properties of the electrochromic device of the present invention prepared as described above and the conventional Ta205 type are clearly improved in color density and response speed, and the lifespan is 1 times longer than that of the conventional type. Improved by an order of magnitude.

[Example 2] In the electrocomic element of [Example 1], the layer 41 was made of ZrO2, the layer 42 was made of 5i02, and the layer 43 was made of Nl (
When the OH)2 thin film was used, the EC characteristics of the device were similarly improved.

〔Effect of the invention〕

As explained above, the present invention provides a p-1-n structure for the intermediate insulating layer of an all-solid-state thin film stacked electrochromic device, thereby increasing the slope of the electronic potential and chemical potential between the reduction coloring layer and the oxidation coloring layer. It was possible to create an ECD with a smooth curve, high memory performance, and excellent speed life.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of the structure of an all-solid-state thin film laminated electrochromic device according to the present invention, and FIG. 2 is a diagram showing a comparison of the coloring/decoloring characteristics of the electrochromic device shown in FIG. 1... Substrate 2... First electrode 3...
Electrochromic layer (oxidation coloring layer) 4... Intermediate insulating layer 5... Electrochromic layer (reduction coloring layer) 6...
・Second electrode Koji Shinbu Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. An all-solid-state thin film laminated electrochromic device, characterized in that an intermediate insulating layer for proton donating and electron blocking has a pin three-layer structure. 2. The electrochromic device according to claim 1, wherein the constituent component of the intermediate insulating layer is an oxide.