JP2574507B2 - Recording method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a recording method for a photoelectrochemical element.

2. Description of the Related Art As an element utilizing the photochromism of a transition metal oxide such as tungsten oxide or molybdenum oxide, for example, an optical recording element capable of reversible color erasing (Japanese Patent Application Laid-Open No. 61-211848) has been proposed. This utilizes optical writing and electrochemical erasing utilizing photoelectrochemical phenomena caused by light having energy equal to or greater than the band gap of the transition metal oxide (including light having a wavelength below the intrinsic absorption edge). is there. The feature lies in recording and electrical erasing in the optical mode = non-thermal mode, and has excellent memory properties and reversibility as characteristics.

Problems to be Solved by the Invention Photochromism is used to realize a large-area rewritable display element utilizing the reversibility of electrochemical coloration of transition metal oxides, memory properties, or good display quality. If this is the case, it is possible to perform recording by light, and it is not necessary to use a matrix electrode required for electrical writing means, and it is possible to achieve high resolution or a large area.

 However, when photochromism is used, a) there is a problem that recording light is limited to ultraviolet light (hereinafter, UV) b) sensitivity to light is insufficient (color density is low).

The problem of recording light arises because all of the intrinsic absorption wavelengths of the transition metal oxide are in the UV range. The use of a UV light source or UV laser is a major drawback in terms of device size, cost, and controllability. The problem of sensitivity is also sufficient for a recording element such as an optical disk, but not enough for a display element.
Practical color density cannot be obtained.

Another object of the present invention is to provide a recording method capable of recording with a small amount of UV light exposure or recording without using UV light and obtaining high-density color development.

Means for Solving the Problems The present invention solves the above-described problems, and in order to reduce the required UV exposure amount or to record visible light, and to improve the color density, the optical properties associated with the decoloration of the transition metal oxide are used. -To provide two new recording methods utilizing changes in electrical properties.

The first recording method includes, in a photoelectrochemical element having a color-forming layer containing at least a transition metal oxide, a first color-forming step using light containing light having a wavelength equal to or less than the intrinsic absorption wavelength end of the transition metal oxide, and A recording method characterized by having a second coloring process using light including light having a wavelength in an absorption wavelength region generated by at least the first coloring process.

The second recording method includes, in a photoelectrochemical element having a coloring layer containing at least a transition metal oxide, a first coloring step by the coloring layer reduction current, and at least an absorption wavelength region generated by the first coloring step. A recording method characterized by having a second coloring process by including light of a wavelength.

Effect In the first recording method, the light irradiating portion slightly develops color and absorbs in the visible light region by the first coloring process using light having a wavelength equal to or less than the intrinsic absorption wavelength end. Next, by irradiating light containing wavelength light in the absorption wavelength region generated by the first color development process, the color development portion is further electrochemically darkened by absorption in the color development wavelength region generated by the first color development process. Color develops.

As a result, the required UV exposure amount can be reduced and visible light signal recording can be performed.

In the second recording method, the reduced portion is slightly colored and absorbs in the visible light region by the first coloring process by the electrochemical reduction current. Next, similarly to the second recording method, by irradiating light containing wavelength light in the absorption wavelength region generated by the first color forming process, the color forming portion is absorbed by the color developing wavelength region generated by the first color forming process. It develops a deeper color electrochemically.

This enables visible light recording without using UV light.

Embodiment First, a description will be given of materials and configurations common to the first and second recording methods.

The coloring layer containing at least a transition metal oxide used in the first and second recording methods is usually formed as follows.

On a transparent substrate such as glass, those that do not require an electrochemical process are directly formed.For those that require an electrochemical process, a transparent electrode such as ITO is formed on a transparent substrate, and then a transition metal oxide coloring layer is formed by vapor deposition. A color developing substrate is formed to have a thickness of 0.1 to 4 μm.

Transition metal oxides are not particularly limited, such as WO ₃ , MoO ₃ , V ₂ O ₅ , TiO ₂ , Nb ₂ O _5, but photochromism and WO ₃ are particularly excellent in the decoloring properties in electrochromism. MoO ₃ is mentioned.

Further, the transition metal oxide does not need to be used alone and may be a mixed film.

The method for forming the transition metal oxide thin film is not limited to the vapor deposition method, but may be a sputtering method, a coating method, or the like.

Transparent substrate is glass or various plastics, transparent electrode is In
Thin films of ₂ O ₃ , SnO ₂ , Au and the like are generally used.

When light is irradiated from the color-forming layer side, the substrate or electrode on which the transition metal oxide color-forming layer is formed does not necessarily need to be transparent.

The electrochemical process in each recording method is performed by forming an electrode on a substrate, and forming a color-forming layer on the color-forming layer of the color-forming substrate so as to face an opposing electrode via an electrolyte.

This electrolyte may be a liquid electrolyte or a fixed electrolyte. Further, in the case of a liquid electrolyte, the solvent may be water or an organic solvent.

From the viewpoint of the quenching characteristics of the transition metal oxide, H ⁺ , Li ⁺ , Na ⁺ , and K ⁺ are preferably present in the electrolyte as cations used in the color forming process by light, and among them, the presence of H ⁺ is the quenching sensitivity. Is preferred.

The material of the counter electrode is not particularly limited, and a counter electrode reaction layer such as a metal hydroxide may be present on the counter electrode.

The photo-coloring process by UV or visible light in each recording method is performed in an atmosphere containing protons such as water, alcohol, and acid, or in an electrolyte containing cations such as H ⁺ , Li ⁺ , Na ⁺ , and K ^+. By doing so, efficient photochromic coloring can be obtained.

 Hereinafter, each recording method will be described.

In each of the color developing substrates used in each of the examples, an ITO transparent electrode (approximately 20Ω / □) was vapor-deposited on a glass substrate, and then tungsten oxide or molybdenum oxide was applied to a thickness of approximately 2 μm.
What was vapor-deposited was used.

 The first recording method will be specifically described.

Example 1 On a molybdenum oxide coloring substrate, in air (humidity 70%)
A xenon lamp was irradiated from the substrate side for 10 seconds, and the whole was slightly colored.

Next, when this semiconductor substrate was irradiated with a semiconductor laser beam having a wavelength of 800 nm and an output of 10 mW for 1 second in a saturated atmosphere of ethanol gas, the irradiated spot developed a deep blue color.

On the other hand, under the same conditions, no color was formed on the substrate not irradiated with xenon light.

As described above, in the present example, a high-density color was selectively obtained by irradiating visible light with slight irradiation of a kesenon lamp.

Example 2 A molybdenum oxide coloring substrate was prepared by adding lithium perchlorate to 0.1M.
/ l dissolved propylene carbonate (4-methyl-1,3
- dioxalane-2-one (crude, water included) immersed in) was irradiated with N ₂ laser (wavelength 337 nm) from the substrate side, the irradiation unit is slightly colored.

Subsequently, when a mercury lamp light having a wavelength of 500 nm or less was irradiated onto the entire surface of the substrate from the substrate side for 10 minutes, the color developed at the laser light irradiated portion became dark and the other portions did not change.

As described above, according to the present embodiment, a recording method in which only the portion irradiated with UV light is selectively and sharply colored is obtained.

 Next, the second recording method will be specifically described.

Example 3 A molybdenum oxide coloring substrate and a platinum electrode were used in Example 2.
When immersed in a propylene carbonate solution of -1.0V applied to the platinum electrode on the coloring substrate side electrode for 2 seconds,
The entire surface was slightly colored.

Next, the substrate was taken out and irradiated with a semiconductor laser beam having a wavelength of 800 nm and an output of mW from the substrate side in an ethanol gas saturated atmosphere.

As described above, in this example, a sharp color was obtained by applying visible light and then applying a small amount of power.

Example 4 A tungsten oxide coloring substrate on which transparent electrodes were formed in a pattern was immersed in the propylene carbonate solution of Example 2, and -1.0 V was applied to the coloring substrate side electrode with respect to the platinum electrode for 2 seconds. The part slightly developed color.

Next, the substrate was taken out, and a mercury lamp light having a wavelength of 500 nm or less was cut under a methanol gas saturated atmosphere.
When the entire surface of the substrate was irradiated from the substrate side for 10 minutes, the color developed in the electrode pattern portion became dark and the other portions did not change.

As described above, in this example, a sharp color was obtained by applying visible light and then applying a small amount of power.

According to the first recording method, that is, in a photoelectrochemical element having a color-forming layer containing at least a transition metal oxide, the first recording method is performed by using light containing light having a wavelength equal to or less than the intrinsic absorption wavelength end of the transition metal oxide. A recording method comprising a color forming step and a second color forming step using light including wavelength light in an absorption wavelength region generated by at least the first color forming step. The amount is small, and recording by an all-optical process is possible.

Further, in a second recording method, that is, in a photoelectrochemical element having a coloring layer containing at least a transition metal oxide, a first coloring step by the coloring layer reduction current and an absorption wavelength region generated by at least the first coloring step. In the recording method characterized by having a second color development process by including light of the wavelength of, the recording can be performed by using only visible light without using a UV light source.

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazuhito Hashimoto 2000-10 Kosugaya-cho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture (56) References JP-A-59-79436 (JP, A) JP-A-61-41127 (JP, A)

Claims (7)

(57) [Claims] 1. A photoelectrochemical element having a color-forming layer containing at least a transition metal oxide, wherein at least a first color-forming step using light containing light having a wavelength equal to or less than the intrinsic absorption wavelength end of the transition metal oxide; A recording method comprising a second coloring process using light including wavelength light in an absorption wavelength region generated by the first coloring process. 2. A photoelectrochemical device having a coloring layer containing at least a transition metal oxide, wherein at least a first coloring step by a reduction current of said coloring layer, and at least a first coloring step.
A second color development process using light including wavelength light in an absorption wavelength region generated by the color development process. 3. The recording method according to claim 1, wherein the first coloring step is performed on the entire surface of the element, and the second coloring step is performed on a part of the element surface. 4. The recording method according to claim 1, wherein the first coloring step is performed on a part of the element surface, and the second coloring step is performed on the entire surface of the element. 5. The recording method according to claim 1, wherein the transition metal oxide is at least one of tungsten oxide and molybdenum oxide. 6. The recording method according to claim 1, wherein the coloring process by light is performed in an atmosphere in which at least one of water, alcohol, and acid is present. 7. The process of coloring by light is performed by H ⁺ , Li ⁺ , Na ⁺ and
3. The recording method according to claim 1, wherein the recording is performed in an electrolyte containing at least one cation of K ⁺ .