JPS6153706B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a so-called electrochromic (hereinafter referred to as EC) device that exhibits reversible color development and decolorization upon application of voltage, and more specifically relates to a transparent substrate having a pair of transparent conductive films and , relates to a transmission type EC element comprising an EC thin film formed on the transparent conductive film, a transparent electrolyte sandwiched between the transparent substrate, and a sealing member encapsulating the transparent electrolyte.

Conventionally, symmetric and asymmetric types have been proposed for this type of EC element in terms of element configuration. As shown in Fig. 1, the symmetrical type has a transparent substrate 1, 1' having a transparent conductive display electrode and counter electrodes 2, 2', and EC thin films 3, 3' of the same type formed on the electrodes 2, 2'. death,
An electrolyte 5 is sandwiched between the pair of substrates, and the periphery is sealed with a sealing member 6. On the other hand, the asymmetric type uses an inert electrode material such as metal or carbon for the counter electrode. Currently, it is considered that an inert electrode is insufficient from the viewpoint of the life of the device, and a symmetrical structure is generally adopted. In this case, since the same type of EC thin film, such as a tungsten oxide thin film, is formed on both the display electrode and the counter electrode, the tungsten oxide on the counter electrode remains colored even when no display is performed. Therefore, a masking material 4 is required to hide this from viewers. Furthermore, it has been impossible to obtain a transmission type element due to such a configuration.

The present invention has been made with consideration to these points, and has improved the EC thin film formed on the counter electrode in the symmetrical element, thereby making it possible to make the element transmissive.

That is, the present invention provides a transparent substrate having a pair of transparent conductive films arranged opposite to each other, a pair of EC thin films formed on the transparent conductive film, and a transparent substrate sandwiched between the pair of transparent substrates. In an EC element comprising an electrolyte containing ions capable of changing the optical properties of an EC thin film and a sealing member encapsulating the electrolyte, the above-mentioned
One of the EC thin films is an EC thin film in which the optical properties change in the ion and electron absorption state when a voltage is applied, including the visible range, and in the emitting state, which does not include the visible range. The present invention provides an EC element characterized in that it is a thin film containing crystalline tungsten oxide in which the main wavelength range in which properties change does not substantially include the visible range.

By adopting such a configuration, the present invention enables EC
The masking material that was required inside the device is no longer necessary, and the structure is simplified and manufacturing is also facilitated. Furthermore, since it is a transmission type element, illumination from the rear is possible, and by placing a background plate at the rear, the background can be colored easily. Furthermore, by making the element transmissive, the application of the EC element is not limited to displays, but can also be used for dimming windows, mirrors, etc.

Hereinafter, the transmission type element according to the present invention will be explained in detail using the drawings.

FIG. 2 shows a transmission type EC element according to the present invention,
A display EC thin film 23 is formed on the electrode 22 of a transparent substrate 21 having a transparent conductive electrode 22. The EC thin film 23 is an amorphous tungsten oxide film formed by a conventional method such as the EB method. Transparent substrate 2
A transparent conductive counter electrode 22' is formed on the counter electrode 1', and ions and electrons that cause EC characteristics reversibly enter and exit the counter electrode 22', but the counter electrode 22' is arranged so as not to cause optical changes in the visible range. An EC thin film 23' containing crystalline tungsten oxide is formed. The EC thin film 23' containing crystalline tungsten oxide has the following properties.

(1) It has a porous structure that allows ions to diffuse by controlling the potential.

(2) It has such mobility that electrons that compensate for the charge of the diffused ions drift and reach the vicinity of the ions.

(3) The lattice, ions, and electrons interact to form a color center.

(4) It has crystallinity such that electrons trapped in the color center can be delocalized to a considerable degree;
Color centers have no absorption in the visible range.

The EC thin film 23' containing such crystalline tungsten oxide is formed, for example, as follows. Tungsten oxide at 1×10 ^-4 Torr to 5×10 ^-3 Torr,
More preferably, a porous tungsten oxide amorphous thin film is formed by vapor deposition at a vacuum level of 5×10 ^-4 Torr to 2×10 ^-3 Torr, and then heat-treated at a temperature of 350° C. to 450° C. to form a porous tungsten oxide film. This is a crystalline thin film.

A substrate 21 on which the pair of EC thin films described above are formed,
A transparent electrolyte 25 is held between 21' and the periphery thereof is sealed with a sealing member 26. In the EC element of the present invention, the masking material 4 required in the conventional element shown in FIG. 1 is unnecessary.

When a voltage is applied to the EC element of the present invention and the display electrode 22 is made negative, ions and electrons are taken into the tungsten oxide amorphous thin film, and WO ₃ (amorphous) + xMe ⁺ + xe ^- → MexWO ₃ (Amorphous) A reaction occurs and the element turns blue in appearance.
The spectral curve at this time is shown in FIG. Then, when the polarity is reversed and the counter electrode becomes negative, a reaction opposite to the above reaction occurs at the display electrode, and the blue color returns to the original transparent state. The spectral curve at this time is shown in FIG.

On the other hand, at this time, the reaction WO ₃ (crystal) + xMe ⁺ +xe ^- →MexWO ₃ (crystal) occurs at the counter electrode, and the same amount of charge as that at the display electrode occurs, so the overall system is balanced in charge. This results in a stable reaction. However, in this case, almost no change is observed on the counter electrode with the naked eye, and the entire device becomes transparent. The spectral curve at this time is shown in FIG.

Contains crystalline tungsten oxide as a counter electrode of the present invention
As mentioned above, the most desirable EC thin film is a thin film containing crystalline tungsten oxide, which is formed in a porous state and then appropriately crystallized by firing. It may contain oxides and sulfides of manganese, niobium, and tantalum.

All known display electrode EC thin films are used.
Examples include oxides and sulfides of at least one metal selected from tungsten, molybdenum, vanadium, chromium, manganese, niobium, tantalum, and titanium, and preferably an amorphous film containing tungsten oxide.

Also, all known electrolytes can be used, but
Salts containing protons, alkali metal ions, silver, and thallium monovalent ions can be mixed with propylene carbonate, acetonitrile, dimethyl sulfoxide, N
- Preferably, it is dissolved in an organic solvent such as methylpyrrolidone.

The EC element of the present invention can be used in combination with a conventional EC thin film, in which ions and electrons that cause EC characteristics can reversibly enter and exit, and a material that does not cause optical changes in the visible range is used as a counter electrode. Since it is a transmission type element used, the EC element 5 as shown in FIG.
Illumination can be achieved by arranging a light source 51 and a reflecting plate 52 behind the EC element 60, or by arranging a light source 61 and a light scattering plate 62 behind the EC element 60 as shown in FIG.

Further, as shown in FIG. 7, a scattering reflector plate 71 made of paper, metal, etc. can be arranged behind the EC element 70 to use it as a reflective type. Furthermore, as shown in FIG. 8, a colored background plate 81 may be placed on the back surface of the EC element 80 to color the background and enhance the display effect.

Example A vacuum deposition apparatus equipped with an ordinary electron gun was applied to a glass substrate having a transparent conductive film at 2×10 ^-5 Torr.
A tungsten oxide film was formed to a thickness of approximately 0.5μ, and this was used as a display electrode plate. In addition, by ^the same method, tungsten oxide was heated at about 1.0
It is formed to a thickness of μ, and then heated at 390℃ in air.
A counter electrode plate was prepared after heat treatment for 20 minutes.

The pair of electrode plates thus formed were placed facing each other, a spacer was placed around the periphery for sealing, and then an electrolyte containing LiClO ₄ dissolved in propylene carbonate at a concentration of 0.5 M/l was injected through a predetermined injection hole. This injection hole was sealed to complete the device. In this state, when a voltage of 3.5V was applied to the device with the display electrode negative, the amorphous tungsten oxide film on the display electrode turned blue. Next, when a voltage of 1.5 V was applied with the display electrode positive, the blue color on the display electrode disappeared, and there was almost no macroscopic change in the crystalline thin film of tungsten oxide on the counter electrode. further after this
Switching was repeated at 1.5V, but the tungsten oxide on the display electrode simply changed color and faded, and the tungsten oxide on the counter electrode showed almost no change, resulting in a transmissive element. This device operated well without any changes even after 300,000 switching cycles.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional symmetrical EC element, Figure 2
The figure is a cross-sectional view of a transmission type ECC element according to the present invention.
1, 1', 21, 21' are transparent substrates, 2, 2', 2
2, 22' are transparent conductive electrodes, 3, 3', 23 are transparent conductive electrodes.
EC thin film, 23' contains crystalline tungsten oxide
EC thin film; 4 is a masking material; 5 and 25 are electrolytes; 6 and 26 are sealing members; FIGS. 3 and 4 are spectral curves of the EC thin film on the display electrode and counter electrode, respectively. 5 to 8 show examples of application of the transmission type EC element of the present invention. 50, 60, 70, 80 are EC elements, 51, 6
1 is a light source, 52 is a reflecting plate, 62 is a light scattering plate, 71
81 indicates a scattering reflector, and 81 indicates a colored background plate.

Claims (1)

[Scope of Claims] 1. A transparent substrate having a pair of transparent conductive films arranged opposite to each other, a pair of electrochromic thin films formed on the transparent conductive film, and a transparent substrate sandwiched between the pair of transparent substrates. In an electrochromic device comprising a transparent electrolyte containing ions that can change the optical properties of the electrochromic thin film and a sealing member that encapsulates the electrolyte, one of the electrochromic thin films is ionized by applying a voltage. and an electrochromic thin film in which the range of changes in optical properties in the electron absorption state includes the visible range and does not include the visible range in the emission state; An electrochromic device characterized by being a thin film containing crystalline tungsten oxide that does not substantially include the visible region. 2. The electrochromic device according to claim 1, wherein one of the electrochromic thin films is a thin film containing amorphous tungsten oxide, and the other is a thin film containing crystalline tungsten oxide.