JP2005099249A - Electrochromic element and driving method of the element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrochromic element which has satisfactory coloring responsiveness, can be driven by voltage having less energy and can easily be manufactured and to provide a driving method of the element. <P>SOLUTION: The electrochromic element comprises a pair of substrates 2 and 4 provided with electrodes 3 and 5, respectively, and a coloring layer 6 and an electrolyte layer 7 interposed between the substrates 2 and 4, and the periphery of the coloring layer 6 and the electrolyte layer 7 is sealed by using a resin material 8. The coloring layer 6 comprises an inorganic or an organic electrochromic material and the electrolyte layer 7 is an ionic liquid. The electrochromic element is driven by applying any one of a DC voltage, a sine waveform voltage or a pulse waveform voltage between the electrodes 3 and 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrochromic device, and more particularly, to an electrochromic device using a phenomenon in which the amount of light absorption increases when an electric field is applied to a light transmission body, and a method for driving the device.

  Conventionally, as a display element, an electrochromic element using a phenomenon that an amount of light absorption increases when an electric field is applied to a light transmitting body is known. For example, Patent Document 1 discloses a structure in which an electrochromic layer, a gel electrolyte, and a charge balance compensation layer are sandwiched between spacers with a transparent electrode between transparent substrates each provided with a transparent electrode.

However, since the electrochromic element uses a sodium hydroxide solution as an electrolyte, it has a problem that the color responsiveness is slow. In addition, since this gel electrolyte requires a certain layer thickness, the drive voltage becomes high, and the manufacturing process is complicated because it requires a spacer to be sandwiched between the substrates. Yes.
JP 2001-167629 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an electrochromic element that has good color responsiveness, can be driven with a low energy voltage, and is easy to manufacture, and a method for driving the element.

  In order to achieve the above object, an electrochromic device according to the present invention comprises a pair of substrates each provided with an electrode, and a coloring layer and an electrolyte layer sandwiched between the pair of substrates, and the electrolyte solution The layer is an ionic liquid, and a sealing material is provided around the coloring layer and the electrolyte layer.

  In the electrochromic device according to the present invention, an inorganic or organic electrochromic material can be used for the coloring layer. The ionic liquid is preferably a pyridine-based, alicyclic amine-based or aliphatic amine-based material. This ionic liquid may be impregnated in the porous sheet. The sealing material is preferably a resin material that cures without being mixed with the ionic liquid.

  The driving method according to the present invention is characterized in that any one of a DC voltage, a sine waveform voltage, or a pulse waveform voltage is applied to the electrode of the electrochromic element.

  In the electrochromic device according to the present invention, since the ionic liquid is used as the electrolyte layer, the response speed of color development is remarkably faster than that using a conventional sodium hydroxide solution. In addition, a small amount of ionic liquid is required, the holding property between the pair of substrates is good, and it is not necessary to provide a spacer between the substrates, and the configuration and the manufacturing process are simplified.

  In addition, since the distance between the substrates (electrodes) is reduced, it is possible to drive with low voltage and good response, and power consumption can be reduced. In addition, stable color development is maintained without deterioration of the color developing layer even when voltage is intermittently applied.

  Embodiments of an electrochromic device and a driving method of the device according to the present invention will be described below with reference to the accompanying drawings.

(Basic element configuration, see Fig. 1)
FIG. 1 shows a basic configuration of an electrochromic device according to the present invention. The element 1 includes an electrode 3 and a substrate 2 and a substrate 4 including an electrode 5 facing each other so that the electrodes 3 and 5 face each other, and sandwiching the coloring layer 6 and the ionic liquid 7 therebetween, Is sealed with a resin material 8. Voltage application lead wires 11 and 12 are connected to the electrodes 3 and 5, respectively.

  Either one side or both sides of the substrate 2 and the electrode 3 and the substrate 4 and the electrode 5 are transparent. Therefore, various materials can be used for the substrates 2 and 4 and the electrodes 3 and 5 as long as the conditions are satisfied. For example, the following combinations of Examples 1 and 2 can be adopted.

Combination example 1
Substrate 2: Transparent glass Electrode 3: Transparent electrode body (ITO film having a thickness of about 0.3 μm)
Substrate 4: Silicon Electrode 5: Aluminum film with a thickness of about 0.5 μm

Combination example 2
Substrate 2: Transparent plastic film Electrode 3: Transparent electrode body (ITO film having a thickness of about 0.2 μm)
Substrate 4: Transparent glass Electrode 5: Transparent electrode body (ITO film having a thickness of about 0.3 μm)

  Various materials can be used for the coloring layer 6 as long as the material causes an electrochromic phenomenon. Inorganic substances include tungsten oxide and iridium oxide. Examples of organic substances include polyaniline, polythiophene, lutetium diphthalocyanine, and TTF-polystyrene. The coloring layer 6 obtained by vacuum-depositing tungsten oxide develops a blue color and becomes transparent when decolored. In addition, the color-developing layer 6 spin-coated with poly-3hexylthiophene develops a red color and becomes transparent when decolored.

  The ionic liquid 7 functions as an electrolytic solution, and it is preferable to use a pyridine-based, alicyclic amine-based or aliphatic amine-based material. Specifically, IL-P2, IL-C3, and IL-A1 manufactured by Guangei Chemical Industry Co., Ltd. can be used.

  As the sealing resin material 8, it is preferable to use a material that cures without being mixed with the ionic liquid 7 such as silicon resin.

(Example 1)
The electrochromic element as Example 1 was produced by the following steps. As the material, any one of the combination examples 1 and 2 may be used.

  Step 1: Tungsten oxide is deposited on the surface of the substrate 4 on which the electrodes 5 are formed using a pattern mask to form the color developing layer 6.

  Step 2: The ionic liquid 7 is applied to the surface of the substrate 2 on which the electrodes 3 are formed, and the substrate 4 is opposed (the colored layer 6 is in surface contact with the ionic liquid 7), taking care not to leave bubbles. Then, a uniform pressing force is applied to the substrates 2 and 4 so that excess ionic liquid oozes out to the surroundings.

  Step 3: The ionic liquid that has soaked out is quickly removed, and the periphery of the coloring layer 6 and the ionic liquid 7 is sealed with the resin material 8.

(Example 2)
Moreover, the electrochromic element as Example 2 was produced according to the following processes. As the material, any one of the combination examples 1 and 2 may be used.

  Step 1: An organic polymer electrochromic material is applied by spin coating on the surface of the substrate 4 on which the electrode 5 is formed, and dried to form the color developing layer 6.

  Step 2: A thin paper in which the ionic liquid 7 is immersed is placed on the surface of the substrate 2 on which the electrode 3 is formed, and the substrate 4 is opposed (the coloring layer 6 is in surface contact with the ionic liquid 7). Air bubbles are removed by applying a uniform pressing force to the substrates 2 and 4.

  Step 3: After the bubbles are removed, the periphery of the coloring layer 6 and the ionic liquid 7 is quickly sealed with the resin material 8.

(See the driving method, FIG. 2 and FIG. 3)
The electrochromic element 1 can be driven by a direct current drive, an alternating current drive and a pulse waveform. A voltage is applied from the lead wires 11 and 12 to the electrodes 3 and 5, and an electric field acts on the coloring layer and the ionic liquid. The decoloring is performed by applying an electric field having a polarity opposite to that at the time of color development.

  A general driving method is driving with a direct current having a predetermined voltage value shown in FIG. Since the electrochromic element 1 according to the present invention uses an ionic liquid as an electrolyte layer, the color response speed is remarkably fast, and the ionic liquid can be thin, so that the distance between the electrodes 3 and 5 is small. It can be driven with a low voltage of 5V.

  In this case, as shown in FIG. 2B, a current of several tens mA flows at the initial time t (1-2 seconds), but decreases to several mA after 1-2 seconds. Therefore, the voltage application may be turned off after the current has decreased to several mA.

  The electrochromic element 1 can be driven by an arbitrary waveform. Since the electrochromic device 1 according to the present invention develops color by the movement of ions, after a reaction by applying a single voltage, color development or decoloration is reduced due to a return phenomenon. If a voltage is repeatedly applied so as to suppress this return phenomenon, the color development (decoloring) is stabilized with a quicker response than the DC drive.

  FIG. 3 shows various drive waveforms. FIG. 3A shows a sine waveform in the positive region, and FIG. 3B shows a pulse waveform obtained by rectifying the sine waveform. FIG. 3C shows a square pulse waveform, and FIG. 3D shows a pulse waveform in which the pulse width is gradually changed.

(Other examples)
The electrochromic device and the driving method of the device according to the present invention are not limited to the above-described embodiments, and can be variously changed within the scope of the gist.

  In particular, the sealing material is not limited to the form in which the resin material is applied, and may be a tape material, and various materials can be used as long as they do not mix with the ionic liquid.

It is sectional drawing which shows the basic composition of the electrochromic element which concerns on this invention. The direct current drive form with respect to the electrochromic element which concerns on this invention is shown, (A) is a chart figure which shows an applied voltage, (B) is a chart figure which shows the electric current change. The various drive waveforms of the electrochromic device concerning the present invention are shown, (A) is a chart figure showing a sine wave, (B) is a chart figure showing a rectified sine wave, (C) is a chart figure showing a square wave, (D) is a chart showing a modification of a square wave.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electrochromic element 2, 4 ... Substrate 3, 5 ... Electrode 6 ... Color development layer 7 ... Electrolyte layer (ionic liquid)
8 ... Resin material for sealing 11, 12 ... Lead wire

Claims (8)

Each consisting of a pair of substrates each provided with an electrode, and a coloring layer and an electrolyte layer sandwiched between the pair of substrates,
The electrolyte layer is an ionic liquid;
A sealing material is provided around the coloring layer and the electrolyte layer;
An electrochromic device characterized by.   The electrochromic device according to claim 1, wherein the coloring layer is an inorganic or organic electrochromic material.   The electrochromic device according to claim 1, wherein the ionic liquid is made of a pyridine-based, alicyclic amine-based, or aliphatic amine-based material.   The electrochromic device according to claim 1, wherein the ionic liquid is impregnated in a porous sheet.   5. The electrochromic device according to claim 1, wherein the sealing material is a resin material that cures without being mixed with the ionic liquid.   6. The method of driving an electrochromic device according to claim 1, wherein a DC voltage is applied.   6. The method of driving an electrochromic device according to claim 1, wherein a sine waveform voltage is applied.   6. The method of driving an electrochromic device according to claim 1, wherein the pulse waveform voltage is applied.

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