JP2774599B2 - Light modulation element - Google Patents

Description

The present invention relates to an electrochromic device, and more particularly, to a light modulation applicable as an all-solid-state variable ND filter whose absorption spectrum characteristic during coloring is neutral (ND) in the visible light region. Related to the element.

(Prior Art) FIG. 6 shows a general structure example of a conventional all solid-state electrochromic device. The electrochromic device shown in FIG. 6 has a first electrode 62 made of a transparent conductive film, a first electrochromic layer 63, an ion conductive electron insulating layer 64 made of a dielectric film, and a second The chromic layer 65 and the second electrode 66 are sequentially laminated.

The substrate 61 is generally formed of a glass plate, but this is not limited to a glass plate, and may be any material as long as it is a colorless and transparent plate such as a plastic plate or an acrylic plate. Not only below but also the second electrode 66
And may be provided on both surfaces according to the purpose (for example, as a protective cover).

The first electrode 62 and the second electrode 66 are formed of an ITO film (SnO _{2 in} In ₂ O _3).
) And NESA film (SnO ₂ : F).

NiO _x , FeO _x , CoO _x , IrO _x , PtO _x , Cr ₂ O ₃ , O
sO _{x and the} like. The reason why the suffix "x" is used here is that the above substances are generally nonstoichiometric compounds and deviate from the stoichiometric ratio.

Zr is used as a material constituting the ion conductive electron insulating layer 64.
O ₂ , HfO ₂ , Ta ₂ O ₅ , Y ₂ O ₃ , SiO ₂ , MgF ₂ , Mb ₂ O ₂ , Cr ₂ O _{3 and the} like are used.

Fifth reducing property facing the first electrochromic layer
Examples of the material constituting the layer include WO ₃ , TiO ₂ , CuO, and SnO ₂ . In the electrochromic device having such a configuration, an electrochemical reaction is induced by applying a voltage between the electrodes 62 and 66 to perform coloring and decoloring.

For example, in FIG. 6, when the oxidized coloring layer 63 is composed of IrO _x , the reduced coloring layer 65 is composed of WO ₃ , and the oxidized coloring layer 3 side is plus (+) and the reduced coloring layer 65 side is minus (−). , IrO _x, and WO ₃ is respectively _{IrO x + yH 2 Oad → IrO} x (OH) y + yH + + ye WO 3 + yH + + ye → H y WO 3 ( where H ₂ Oad shows the adsorbed water contained in the device) It is considered that the reaction produces the colored species IrO _x (OH) _y · H _y WO ₃ and develops a color, and by reversing the electric field, the reverse reaction to the above equation occurs and the color is erased.

(Problems to be Solved by the Invention) In the above-described structure, Ir is used as an oxidative coloring substance.
There is a substance whose absorption spectrum at the time of coloring is neutral, as represented by O _x , NiO _x , CoO _x, etc. Instead, for example, there has been proposed a variable ND element for neutralizing during coloring by non-coloring of WO ₃ which is a reducible coloring color by heat treatment or the like (see JP-A-62-203133).

However, in a device such as the one proposed above, the impedance of the system becomes high, the potential balance of the system is lost, the coloring density is reduced, and the life is shortened by applying a high voltage to the device to avoid it. There was a problem that it would.

Accordingly, an object of the present invention is to solve the above-mentioned problems and realize a highly reliable electrochromic element having a neutral absorption spectrum characteristic, thereby realizing the practical use of a variable ND element that has not yet reached the practical use level. It is to measure.

(Means for Solving the Problems) The above object is achieved by the present invention described below.

That is, the present invention provides an all-solid-state variable ND device in which a first electrochromic layer, an intermediate ion-conducting electron insulating layer, and a second electrochromic layer are sandwiched between two transparent electrodes, wherein the first electrochromic layer is formed of iridium oxide. Alternatively, the light modulation element is made of a hydroxide, and the second electrochromic layer is made of a mixed oxide of indium oxide doped with tungsten oxide or molybdenum oxide.

(Function) According to the present invention, the color on the first electrochromic layer changes neutrally in the visible light region.
Reducing electrochemical reaction (reaction current flows on the reducing side) in the second electrochromic layer facing IrO _x
By using a low-impedance mixed oxide, the impedance of the entire device is reduced, and the potential balance of the entire system is improved.
By providing an ND element, the practical application of the variable ND element can be further enhanced.

(Example) The light modulation element of the present invention will be described in more detail based on examples.

Embodiment 1 FIG. 1 shows a configuration of a light modulation element of the present invention. Thickness 1,00
A glass substrate 11 on which a 0Å ITO transparent electrode layer 12 is formed is prepared, and a 30Å-thick IrO _x layer and a 400Å-thick metal iridium are formed on the conductive layer 12 by high-frequency reactive sputtering. Anodization was performed by a rectangular wave in a 0.01NH ₂ SO ₄ aqueous solution to form an iridium oxide layer 13 of 1,200 °.

Subsequently, a Ta ₂ O ₅ layer 14 is laminated 8,000 mm by an electron beam heating method, and the reactivity of O ₂ is further determined using a mixed pellet of In ₂ O ₃ and WO ₃ (1 to 10% by weight) as an evaporation source. After forming a mixed oxide layer 15 of In ₂ O ₃ and WO ₃ by 1,500 に て by an ion plating method, the reactive ion plating method of O ₂ is also used.
The device of the present invention was formed by forming 1,200 mm of the ITO transparent electrode 16.

The composition of the mixed oxide layer was analyzed by IMA and X-ray fluorescence analysis. FIG. 2 shows the relationship between the sheet resistance of the mixed oxide film and the composition ratio of the optical band gap.

As a result of driving the device using the mixed oxide films having the respective composition ratios formed as described above, the composition ratio (W / In: at.%) Was 1
The device using 10 to 10 at.% Has a driving voltage of ± 1.5 V and Δ0D to 0.5
It operated with a response of about 500 msec., And its absorption spectrum was almost neutral in the visible region. FIG. 3 shows the response characteristics at that time, and FIG. 4 shows the wavelength characteristics of the transmittance.

In the configuration of Example 1, only the layer of the first FIG. 15 an In ₂ O ₃
A mixed pellet of Mo and MoO ₃ (1% to 10% by weight) was replaced with a mixed oxide layer by a reactive ion plating method of O ₂ as an evaporation source, and the other layers were the same as in Example 1. When the element of the present invention was formed, the absorption spectrum was neutral in the visible region almost in the same manner as in Example 1.

FIG. 5 shows the relationship between the sheet resistance of the mixed oxide film and the composition ratio of the optical band gap when Mo / In (at.%) Is 1 to 10 at.%.

(Effect of the Invention) As described above, in order to realize an all solid-state variable ND element, an electrochromic element using IrO _x whose absorption spectrum is neutral in the visible light region and whose absorption spectrum is neutral in the visible light region as a first electrochromic layer is used. By using a low-impedance mixed oxide that undergoes a reducing electrochemical reaction (a reaction current flows on the reducing side) in the second electrochromic layer opposite to the device, the impedance of the entire device is reduced, and the potential balance of the entire system is improved. By doing so, it was possible to provide a highly reliable all-solid-state ND device that was practically used.

[Brief description of the drawings]

FIG. 1 is a block diagram of an all-solid-state variable ND light modulation device of the present invention. FIGS. 2 and 5 show the relationship between the composition ratio of the sheet resistance and the optical band gap of the mixed oxide film of the present invention. FIG. 4 is a diagram showing a response characteristic of the light modulation device of the present invention, FIG. 4 is a wavelength characteristic of transmittance of the light modulation device of the present invention, and FIG. 11, 61: substrate 12, 62: first transparent electrode 13, 63: first electrochromic layer 14, 64: ion conductive electron insulating layer 15: second electrochromic layer 16, 66: second transparent electrode 65: the present invention Electrochromic layer made of mixed oxide film

Claims (2)

(57) [Claims] 1. An all-solid-state variable ND device having a first electrochromic layer, an intermediate ion-conducting electron insulating layer, and a second electrochromic layer sandwiched between two transparent electrodes, wherein the first electrochromic layer is formed of iridium oxide or iridium oxide. A light modulation element comprising a hydroxide, and wherein the second electrochromic layer comprises a mixed oxide of indium oxide doped with tungsten oxide or molybdenum oxide. 2. The light modulation device according to claim 1, wherein the proportion of the dopant oxide in the second electrochromic layer is 1 to 10% by weight.