JPH0596858A - Optical functional element with memory properties - Google Patents

Abstract

PURPOSE:To provide an optical functional element in which a time capable of stably holding the magnitude of a variation in conductivity of the element according to an optical signal and a varied state, i.e., so-called memory properties are improved in the element having a function capable of continuing conductivity of a photosensitive layer varied by irradiating it with a light even after the irradiation of the light. CONSTITUTION:A photosensitive layer is formed between electrodes, at least one of which has optical permeability. The layer is formed by dispersing hole transporting low molecule compound having one or more nitrogen atoms in one molecule, compound having memory property imparting function in which the conductivity of the layer varied by irradiating it with a light is continued even after the irradiation with the light and electron absorptive compound having no memory property imparting function to be used as required in binder polymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical functional device having a memory property, and more specifically, it utilizes a photosensitive layer made of a specific organic material, so that the conductivity of the photosensitive layer is changed by the irradiation of light. The present invention relates to an optical functional device having a function of maintaining the property even after light irradiation. In addition, in the present invention, the above function is referred to as a memory property.

[0002]

2. Description of the Related Art In recent years, active research has been conducted to apply the functions of organic materials to the electronics field. Then, several products such as liquid crystal displays, capacitors, and photoconductors for optical printers are put on the market, and the market is expanding rapidly. With the success of these products, it was revealed that the durability, which was conventionally regarded as a drawback of organic materials, is not inferior to inorganic materials and in some cases superior to inorganic materials due to optimization of materials and use conditions. I was killed.

From the background described above, researches using organic materials for elements, which are basic components of electronics, have been actively conducted. Among these, some studies have been conducted on switching elements and photodiode elements. As a typical example, research on switching phenomena using a copper-tetracyanoquinodimethane complex whose resistance state changes under a high electric field is known (Applie).
d Physics Letters, Volume 34, 405
P., 1979). Then, since the above phenomenon exhibits a memory property, thereafter, researches on switching elements using the copper-tetracyanoquinodimethane complex have been conducted in various places.

The above-mentioned switching element having a memory property by an electric field has also been studied for other organic materials such as a thin film of a certain phthalocyanine. However, these elements exhibit a function by applying a voltage, and therefore, in order to miniaturize the element or partially apply a voltage, it is necessary to finely process the electrodes and devise a voltage application method. is there. Therefore, there are drawbacks such as high manufacturing cost, restrictions on processing and application,
Moreover, the memory performance is not sufficient.

On the other hand, an optical functional element, for example, a switching element using an optical signal, can widely change the wavelength and intensity of input light, the irradiation area, the irradiation time, and the like, and also has a wide range of applications. It is a promising future device. As an element having this type of memory property, for example, an optical functional element in which a conductive polymer layer made of polypyrrole doped with iodine is provided between a photoconductive layer made of polyvinylcarbazole and trinitrofluorenone and an electrode is reported. It is (Japanes Jou
rnal of Applied Physics, 3
0, 1002, 1991).

[0006]

However, the memory effect of the above-mentioned optical functional element is not sufficient, and it returns to the original state in a short time, so that it is difficult to put it into practical use. As described above, although much research has been conducted on optical functional devices having a memory property, basic performance such as memory retention performance is not sufficient, and it is difficult to put the device into practical use at present. The present invention has been made in view of the above circumstances, and an object thereof is to improve the magnitude of the change in electrical conductivity of an element due to an optical signal and the time during which the changed state can be stably maintained, that is, the so-called memory characteristic is improved. It is to provide an optical functional element.

[0007]

That is, the gist of the present invention is that a photosensitive layer is formed between electrodes, at least one of which has a light-transmitting property, and the photosensitive layer has at least one nitrogen atom in its molecule. A low molecular weight compound having a hole-transporting property, a compound having a memory property-imparting function for maintaining the electrical conductivity of a photosensitive layer changed by light irradiation after light irradiation, and a memory property-imparting function optionally used The present invention resides in an optical functional device having a memory property, which is characterized in that an electron-withdrawing compound is dispersed in a binder polymer.

The present invention will be described in detail below. First, the electrodes will be described. The electrode is formed as a conductive thin film layer on the support. As the support, a quartz or glass plate, a metal plate or a metal foil, a plastic film or a sheet, and the like are used, but a glass plate, a transparent plastic (polyester, polymethacrylate, polycarbonate, etc.) plate and the like are preferable. A metal plate or the like that can be used as an electrode can also serve as a support.

The electrode forming material is usually aluminum,
A metal such as gold, silver, nickel, indium, palladium, tellurium, a metal oxide such as indium and / or tin, a conductive resin such as copper iodide, carbon black, and poly (3-methylthiophene) is used.

When the electrode forming material is a metal or a metal oxide, the conductive thin film layer is usually formed by a sputtering method, a vacuum deposition method or the like, but it is formed by another method depending on the kind of the electrode forming material. It For example, in the case of fine particles of metal such as silver, copper iodide, carbon black, fine particles of conductive metal oxide, fine powder of conductive resin, etc., the electrode forming material is dispersed in an appropriate binder resin solution and then the support is used. It is formed by the method of coating on top. Further, in the case of a conductive resin, it can be directly formed on the support by electrolytic polymerization. The conductive thin film layers can be laminated with different materials.

The thickness of the conductive thin film layer is not particularly limited, but it is preferably at least 50 Å or more for uniform expression of conductivity. On the other hand, when light transmission is required,
It is necessary not to exceed the film thickness that satisfies the transmittance. Even with the coating method that increases the film thickness, the film thickness is
It is usually 100 μm or less.

In the present invention, it is necessary that at least one of the electrodes is a light transmissive electrode. The light transmittance does not necessarily have to cover the entire wavelength range, but at least the light transmittance in the wavelength range of the light absorbed by the photosensitive layer is required. The higher the light transmittance, the more preferable in terms of irradiation light efficiency. The transmittance is at least 10% or more, practically 30% or more,
It is preferably 60% or more.

Next, the photosensitive layer formed between the electrodes will be described. The photosensitive layer is a low-molecular compound having a hole-transporting property having one or more nitrogen atoms in the molecule, a compound having a memory property-imparting function of maintaining the electrical conductivity of the photosensitive layer changed by irradiation of light even after irradiation with light, and An electron-withdrawing compound having no memory-providing function, which is used as necessary, is dispersed in a binder polymer.

First, the low molecular weight compound having a hole transporting property will be described. The low molecular weight compound having a hole-transporting property acts as a carrier for transporting holes which are charge carriers in the photosensitive layer. The hole transport phenomenon can be regarded as an electron transfer between molecules or a redox reaction, and an electron donating compound having a small ionization potential is suitable for effective hole transport.

In the present invention, a compound having one or more nitrogen atoms in the molecule is used as the hole transporting low molecular weight compound in view of the above-mentioned purpose. In particular, a compound having two or more nitrogen atoms in the molecule and having a good orientation alignment between the molecules is suitable. The form of the nitrogen atom is, for example, a dialkylamino group such as a diethylamino group, an amino group directly bonded to an aromatic hydrocarbon or an aromatic heterocycle by a diarylamino group such as a diphenylamino group, and the like. Examples thereof include a hydrazo group and a hydrazono group bonded to a hydrocarbon or an aromatic heterocycle, and other examples include a nitrogen atom constituting the heterocycle. Then, examples of the heterocycle include carbazole, indole, pyrazole, pyrazoline, oxazole and the like.

The hole transporting low molecular weight compound as described above is easier to manufacture than the high molecular weight compound, and the impurities can be easily removed by purification. Little deterioration in characteristics. Further, since the low molecular weight compound is generally excellent in compatibility with the binder polymer, it is easy to increase the hole mobility by increasing the content in the photosensitive layer. In the present invention, the low molecular weight compound having a hole-transporting property is a hydrazone compound, particularly the following chemical formula [Chemical formula 4] (Chemical formula 1)
The same as the above) is preferably used.

[0017]

[Chemical 4]

In the above chemical formula [Chemical Formula 4], A represents a monovalent or divalent organic group containing at least one aromatic hydrocarbon ring or aromatic heterocycle, and these rings represent a substituent. You may have. Specifically, the following (a)-
The organic group described in (d) can be mentioned.

(A) A monovalent or divalent organic group derived from benzene, naphthalene, anthracene, pyrene, perylene, phenanthrene, fluoranthene, acenaphthene, acenaphthylene, azulene, fluorene, indene, tetralin, naphthacene and the like. The organic group is an example containing at least one aromatic hydrocarbon ring. (B) A monovalent or divalent organic group derived from pyrrole, thiophene, furan, indole, carbazole, pyrazole, pyridine, acridine, phenazine, benzothiophene, benzofuran and the like. The organic group is an example containing at least one aromatic heterocycle.

(C) A monovalent or divalent organic group derived from a compound in which each of the above organic groups is directly bonded. The above compounds include biphenyl, terphenyl, phenylanthracene, bithiophene, terthiophene,
Bifuran, thienylbenzene, thienylnaphthalene, pyrrolylthiophene, N-phenylcarbazole and the like can be mentioned. (D) A monovalent or divalent organic group derived from a compound in which each of the above organic groups is bonded via a bonding group. As the above-mentioned bonding group, an alkylene group which may have a substituent represented by the following chemical formula [Chemical formula 5] or a divalent organic group represented by the following chemical formula [Chemical formula 6] Is mentioned. Further, a bonding group in which such an alkylene group and a divalent organic group are combined can be mentioned.

[0021]

[Chemical 5]

[0022]

[Chemical 6]

As a specific example of the compound corresponding to (d), for example, xanthene, thioxanthene, indoline, phenothiazine represented by the following chemical formula [ [Chemical formula 7].

[0024]

[Chemical 7]

In addition to the above, specific examples of the compound corresponding to (d) include diphenylmethane, stilbene,
Examples thereof include tolan, 1,4-diphenylphthaldiene, diphenyl ether, diphenyl sulfide, N-methyldiphenylamine, triphenylamine and azobenzene. Furthermore, instead of the benzene ring of these compounds, compounds in which other aromatic rings or heterocycles are combined by using a bonding group can be cited.

Examples of the substituent that the aromatic hydrocarbon ring and / or the aromatic heterocycle in the above (a) to (d) may have include, for example, a methyl group, an ethyl group, a propyl group and a butyl group. , Lower alkyl group such as hexyl group, lower alkoxy group such as methoxy group, ethoxy group, butoxy group, aralkyl group such as allyl group, benzyl group, naphthylmethyl group and phenethyl group, phenoxy group, aryloxy group such as trioxy group Examples include arylalkoxy groups such as benzyloxy group and phenethyloxy group, aryl groups such as phenyl group and naphthyl group, arylvinyl groups such as styryl group and naphthylvinyl group, and dialkylamino groups such as dimethylamino group and diethylamino group. .. And
The alkyl component in these substituents may contain an ether group, an ester group, a cyano group, a sulfide group or the like.

In the above chemical formula [Chemical Formula 4], R ¹ , R ² and R
³ , R ⁴ and R ⁵ are each a hydrogen atom or an alkyl group which may have a substituent, an aralkyl group, an aromatic hydrocarbon group,
Represents a heterocyclic group. Specific examples of R ^{1 to} R ⁵ include lower alkyl groups such as methyl group, ethyl group, propyl group, butyl group and hexyl group, aralkyl groups such as benzyl group and phenethyl group, phenyl group, naphthyl group and acenaphthyl group. ,
An aromatic hydrocarbon group similar to A such as an anthryl group and a pyrenyl group, a thienyl group, a bithienyl group, a carbazole group, an indolyl group, a furyl group, an indoline group and the like heterocyclic group similar to that in A can be mentioned. ..

The substituents that each of the organic groups R ^{1 to} R ⁵ may have include a methyl group, an ethyl group,
Lower alkyl group such as propyl group, butyl group and hexyl group, lower alkoxy group such as methoxy group, ethoxy group, butoxy group, aryloxy group such as phenoxy group and trioxy group, arylalkoxy group such as benzyloxy group and phenethyloxy group Group, an aryl group such as a phenyl group and a naphthyl group, a substituted amino group such as a dimethylamino group, a diethylamino group, a phenylmethylamino group and a diphenylamino group. However, R ¹ may form a ring together with A. As such an example, an organic group represented by the following chemical formula [Formula 8] can be given.

[0029]

[Chemical 8]

In the above chemical formula [Chemical formula 4], R ⁶ and R ⁷ are
An alkyl group which may have a substituent, an aralkyl group,
It represents an allyl group, an aromatic hydrocarbon group or a heterocyclic group. Specifically, lower alkyl groups such as methyl group, ethyl group, propyl group and butyl group, aralkyl groups such as benzyl group, phenethyl group and naphthylmethyl group, aromatic hydrocarbons such as allyl group, phenyl group and naphthyl group. Represents a heterocyclic group such as a group, a pyridyl group, a thienyl group, a furyl group and a pyrrolyl group.
Examples of the substituent which these may have include the above R ¹ and
The same substituents as in R ² , R ³ , R ⁴ and R ⁵ can be mentioned. However, R ⁶ and R ⁷ may be combined to form a ring, and examples thereof include an organic group represented by the following chemical formula [Chemical formula 9].

[0031]

[Chemical 9]

In the above chemical formula [Chemical Formula 4], l is 0 or 1,
m represents an integer of 0, 1 or 2, and n represents an integer of 1 or 2. Note that n
Represents 1 when A is a monovalent group and 2 when A is a divalent group.

Among the hydrazone compounds represented by the chemical formula [Formula 4], a hydrazone compound in which A is a carbazole ring is particularly preferable. The following chemical formula [Chemical formula 10]
Are some of such hydrazone compounds.

[0034]

[Chemical 10]

Next, the compound having a memory property-imparting function will be described. Memory properties can be achieved by numerous compounds. Typical compounds include, for example, protic acids such as chloroacetic acid and orthobenzoylbenzoic acid, aromatic diazonium salts, triarylmethanes such as leuco crystal violet and leucomalachite green, halogenated methylene iodide, hexachloroethane and the like. Hydrocarbon, 1,3,5-tribromobenzene,
Aromatic halogen compounds such as 9,10-dichloroanthracene and 9,10-dibromoanthracene, halogenated ketone compounds such as benzamide, nitrophenol, nitroaniline, hexachloroacetone and bromoacetophenone, acetyl chloride, acetyl bromide and chlorobenzoyl chloride. And the like, acid anhydrides such as phthalic anhydride, and thioketones such as thiomichler's ketone. In particular, an aromatic halogen compound in which two or more chlorine atoms and / or bromine atoms are substituted or a thioketone represented by the following chemical formula [Chemical formula 11] (same as [Chemical formula 2]) is preferable.

[0036]

[Chemical 11]

In the above chemical formula [Chemical formula 11], Ar ₁ and Ar
₂ represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent, and specifically, the same aromatic hydrocarbon group as in A in the above chemical formula [Chemical Formula 4] Group or an aromatic heterocyclic group. The following chemical formula [Chemical formula 1
[2] is an example of preferable thioketones.

[0038]

[Chemical formula 12]

Next, the electron-withdrawing compound having no memory property-imparting function will be described. The above-mentioned electron-withdrawing compound is used as an optional component, but has the following effects. That is, in the optical functional device of the present invention, when the holes move in the photosensitive layer, the holes are trapped in the traps in the photosensitive layer, and when repeatedly used, the trapped charges cause the charges in the photosensitive layer to be changed. descend. as a result,
The mobility of the carrier is lowered and the electrical conductivity is gradually lowered, so that the optical functional element finally fails to exhibit its function. The electron-withdrawing compound having no memory property-providing function effectively prevents charges from being trapped in the photosensitive layer and solves the above-mentioned problem of loss of function.

Examples of the electron-withdrawing compound having no function of giving a memory property include, for example, nitro group, cyano group, acyloxy group, alkoxycarbonyl group, cyanovinyl group,
An aromatic compound having at least one of a sulfonyl group, a sulfinyl group and a sulfonyloxy group as a substituent is used. And, as the aromatic compound, for example, benzene, naphthalene, anthracene, acenaphthene, indene, fluorene, biphenyl, aromatic hydrocarbon compounds such as stilbene, benzoquinone, indanone,
Examples thereof include aromatic quinone compounds such as tetralone, naphthoquinone and anthraquinone, and aromatic heterocyclic compounds such as thiophene, carbazole, pyrazole, pyridine, quinoline, oxadiazole, benzoxazole and benzothiazole. Among the above electron-withdrawing compounds, a dicyanovinyl compound represented by the following chemical formula [Chemical Formula 13] (the same as [Chemical Formula 3]) is preferable.

[0041]

[Chemical 13]

In the above chemical formula [Chemical Formula 13], Ar ₃ is an aromatic hydrocarbon group which may have a substituent, and X is an alkyl group or an aromatic hydrocarbon group which may have a substituent. The same aromatic hydrocarbon group as in A in the above chemical formula [Chemical Formula 4] can be mentioned. In the chemical formula [Chemical Formula 13], p represents an integer of 0, 1 or 2. The following chemical formulas [Chemical formula 14] and [Chemical formula 15] are examples of preferable dicyanovinyl compounds.

[0043]

[Chemical 14]

[0044]

[Chemical 15]

Next, the binder polymer will be described. The binder polymer is preferably a polymer that has good compatibility with each of the above compounds and does not adversely affect the movement of charge carriers in the layer. For example, polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid ester, methacrylic acid ester, butadiene, polyvinyl acetal, polycarbonate, polyester, polysulfone,
Examples thereof include polyphenylene oxide, polyurethane, cellulose ester, cellulose ether, alkyd resin, phenoxy resin, silicon resin and epoxy resin. Among these, polyester resins, polycarbonate resins, methacrylic resins, acrylic resins and phenoxy resins are preferable, and polycarbonate resins and methacrylic resins are particularly preferable.

The amount of the binder polymer used is usually in the range of 0.3 to 30 times by weight, preferably 0.7 to 10 times by weight, based on the hole transporting low molecular weight compound. The amount of the compound having the memory property-imparting function is usually 0.001 to 30 with respect to 100 parts by weight of the binder polymer.
The amount is preferably 0.01 to 20 parts by weight, and the amount of the electron-withdrawing compound having no memory property imparting function is usually 0.01 to 30 parts by weight with respect to 100 parts by weight of the binder polymer. It is preferably in the range of 0.1 to 20 parts by weight.

The photosensitive layer in the optical functional element of the present invention comprises a binder polymer in which the above-described low-molecular compound having a hole-transporting property, a compound having a memory property-imparting function, and an electron-withdrawing compound which is optionally used are dispersed. However, if necessary, additives such as a plasticizer, an ultraviolet absorber and an antioxidant can be added. And
The film thickness of the photosensitive layer depends on the electric field strength necessary for the operation of the optical functional element,
Determined by the range of power supply voltage, but usually 100 μm
The following is preferably 30 μm or less. The lower limit of the film thickness is 0.01 μm from the viewpoint of ensuring the uniformity of the coating film.
The thickness is preferably 0.1 μm.

Next, a method of manufacturing the optical functional element of the present invention will be described. The optical functional element of the present invention is prepared by dissolving each component of the above-described photosensitive layer and various additive components used as necessary in a solvent to prepare a coating solution, and coating the coating solution on the electrode. It is manufactured by drying to form a photosensitive layer and then laminating electrodes. The electrodes may be laminated by a pressure bonding method as well as a sputtering method or a vapor deposition method. Also, a manufacturing method in which the photosensitive layers formed on the electrodes are integrated by thermocompression bonding can be employed.

The optical functional device of the present invention is insulative in the absence of light irradiation, but when irradiated with light in the absorption wavelength range of the photosensitive layer, it exhibits a switching phenomenon in which the electrical conductivity is increased and the current is remarkably increased. To increase. And the above state is
It has a memory property that continues stably for a long time after light irradiation.
The memory property can be released by heating, and the memory property is reversible.

Although the mechanism of the above phenomenon is not sufficiently clear at the present time, it is clear that it is not due to chemical decomposition of the components of the photosensitive layer because it is a reversible phenomenon. However, for the time being, the following can be hypothesized. That is, a low-molecular compound having a hole-transporting property, a compound having a memory property-imparting function, a binder polymer, or the like causes prototropy, isomerization, a change in conformation, a change in orientation state, or the like alone or between molecules, and, for example, By changing the polarization in the vicinity of the electrode interface, the energy barrier at the interface is lowered, and changes such as facilitating the inflow of charges from the electrode occur, thereby increasing the conductivity. Then, the memory function is expressed by the stable and sustained state changed in this way.

The optical functional device of the present invention is used by applying a DC voltage between the electrodes. Then, prior to use, light in the absorption wavelength region of the photosensitive layer is irradiated to increase the electrical conductivity of the photosensitive layer. In this case, if light irradiation is performed with a DC voltage applied between the electrodes, the electroconductivity of the photosensitive layer is sensitized to a higher level. That is, the optical functional element of the present invention can control the sensitivity of the optical functional element by the electric field intensity, and can increase the electric conductivity sufficiently by increasing the electric field intensity even when the irradiation light is weak. You can Whether or not the optical functional element of the present invention is used after being sensitized is appropriately determined depending on the purpose of use. In the above-mentioned sensitization, the higher the applied DC voltage is, the greater the sensitizing effect is, but if the DC voltage is too high, the optical functional element may cause a dielectric breakdown. Is set to 10 ⁸ V / cm or less, usually 10 ^-3 to 1
It is set to 0 ⁷ V / cm, preferably 10 ^-2 to 10 ⁷ V / cm.

[0052]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Example 1 <Production of optical functional element> 0.2 parts by weight of 4,4'-bis (dimethylamino) thiobenzophenone, N-ethyl-3
-Carbazole carbaldehyde diphenylhydrazone 8
A coating solution was prepared by dissolving 0 part by weight and 100 parts by weight of polycarbonate in 880 parts by weight of dioxane. Thickness 1
The above coating solution was applied onto the ITO electrode layer formed on a 00 μm polyester film so that the film thickness after drying was 13 μm, and dried to form a photosensitive layer. Then, aluminum was vacuum-deposited on the surface of the photosensitive layer to form a circular counter electrode having a diameter of 1 cm, and an optical functional element was produced.

<Evaluation of Memory Property (1)> Output from the transparent electrode (ITO electrode) side of the above-mentioned optical functional element 100 μW /
monochromatic light with a wavelength of 435 nm in cm ² for 100 seconds (10 m
After irradiation with J / cm ² ), the current-voltage characteristics of the optical functional element were measured. The obtained results are shown in FIG. In FIG. 1, the horizontal axis represents voltage (V), the vertical axis represents current, the solid line represents the result after exposure, and the broken line represents the result before exposure. As is clear from FIG. 1, in both cases where the transparent electrode side is the positive electrode (the positive voltage side in FIG. 1) and the transparent electrode side is the negative electrode (the negative voltage side in FIG. 1), the current value is In comparison, when applied with 10 V, it increases about 7 times. And this state is 10 at room temperature.
I confirmed that it would be maintained for more than an hour.

<Evaluation of Memory Property (2)> By storing the above-mentioned optical functional element in a thermostat at 120 ° C. for 5 minutes, the memory state was erased and the current value was returned to the original state. Then, a DC bias of 100 V was applied to the optical functional element so that the transparent electrode side became a positive electrode, and monochromatic light having a wavelength of 435 nm with an output of 100 μW / cm ² was irradiated from the transparent electrode side for 100 seconds (10 mJ / cm ² ). The current-voltage characteristics of the optical functional element were measured. The obtained results are shown in FIG. 2 in the same manner as in FIG. As is clear from FIG. 2, in both cases where the transparent electrode side is the positive electrode and where the transparent electrode side is the negative electrode, the current value increases about 40 times when 10 V is applied, compared to before the exposure. Then, it was confirmed that this state was maintained at room temperature for 10 hours or more.

Example 2 <Preparation of optical functional device> 7.0 parts by weight of 9,10-dibromoanthracene, 80 parts by weight of N-ethyl-3-carbazolecarbaldehyde diphenylhydrazone and 100 parts by weight of polycarbonate were added to 880 parts by weight of dioxane. A coating solution was prepared by dissolving. On the ITO electrode layer formed on a polyester film having a thickness of 100 μm, the above-mentioned coating solution is applied so that the film thickness after drying becomes 15 μm, and dried.
A photosensitive layer was formed. Then, aluminum was vacuum-deposited on the surface of the photosensitive layer to form a circular counter electrode having a diameter of 1 cm, and an optical functional element was produced.

<Evaluation of Memory Property> After illuminating 5000 lux of white light from the transparent electrode side of the above-mentioned optical functional element for 5 minutes, the current-voltage characteristic of the optical functional element was measured. The obtained results are shown in FIG. 3 in the same manner as in FIG. As is clear from FIG. 2, the current value increases about 2 to 3 times at the time of applying 10 V compared to before the exposure regardless of whether the transparent electrode side is the positive electrode or the negative electrode. And this state is 10 at room temperature.
I confirmed that it would be maintained for more than an hour.

Example 3 <Fabrication of optical functional element> In Example 1, further, 4-nitrodicyanovinylbenzene as an acceptor 3.
An optical functional device was produced in the same manner as in Example 1 except that the coating liquid in which 0 part by weight was dissolved was used.

<Evaluation of Memory Property> A wavelength of 435 n at an output of 100 μW / cm ² from the transparent electrode side of the above optical functional element.
After irradiating m monochromatic light for 100 seconds (10 mJ / cm ² ),
As a result of measuring the current-voltage characteristics of the optical functional element, the same current-voltage characteristics as those shown in FIG. 1 were shown. In addition, by storing the above-mentioned optical functional element in a thermostat at 120 ° C for 5 minutes, the memory state is erased and the current value is returned to the original state, and the same light irradiation as above is performed again to perform the memory state. And As a result of repeating such a memory state and the operation of erasing thereof, the above-mentioned optical functional element was less deteriorated in memory property than the optical functional element of Example 1 in which the photosensitive layer did not contain an acceptor.

[0059]

The optical functional element of the present invention is characterized in that it exhibits a switching function by an optical signal, and this state is stably memorized and has reversibility. Furthermore, since the photosensitive layer that absorbs light is formed by coating, it has the characteristics of being easy to manufacture and having a large area. It can be expected to be applied to various applications such as sensors, sensors, and pattern processing.

[Brief description of drawings]

FIG. 1 is a measurement result of current-voltage characteristics of the optical functional device of the present invention obtained in Example 1.

2 is a measurement result of current-voltage characteristics of the optical functional device of the present invention obtained in Example 1. FIG.

3 is a measurement result of current-voltage characteristics of the optical functional device of the present invention obtained in Example 2. FIG.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoteru Fujii Sanboshi Kasei Co., Ltd. Research Institute, 1000, Kamoshida-cho, Midori-ku, Yokohama-shi, Kanagawa

Claims (9)

[Claims] 1. A photosensitive layer is formed between electrodes, at least one of which has a light-transmitting property.
Hole transporting low molecular weight compound having at least one nitrogen atom,
A compound having a memory property-imparting function for maintaining the electrical conductivity of the photosensitive layer changed by light irradiation after light irradiation and an electron-withdrawing compound having no memory property-imparting function used as necessary are dispersed in a binder polymer. An optical functional element having a memory property, which is characterized by being configured as follows. 2. The optical functional element having a memory property according to claim 1, wherein the low molecular compound having a hole transporting property is a hydrazone compound. 3. The hydrazone compound is a compound represented by the following chemical formula [Chemical formula 1].
An optical functional device having the described memory property. [Chemical 1] (In the chemical formula [Chemical Formula 1], A represents a monovalent or divalent organic group containing at least one aromatic hydrocarbon ring or aromatic heterocycle, and these rings may have a substituent. . R
¹ , R ² , R ³ , R ⁴ , and R ⁵ represent a hydrogen atom or an alkyl group which may have a substituent, an aralkyl group, an aromatic hydrocarbon group, or a heterocyclic group, and R ⁶ , R ⁷ Represents an optionally substituted alkyl group, aralkyl group, allyl group, aromatic hydrocarbon group or heterocyclic group, l is 0 or 1, m is 0, 1 or 2, n is 1 or Represents an integer of 2.
However, A and R ¹ may combine with each other to form a ring, and R ⁶ and R ⁷ may combine with each other to form a ring) 4. In the chemical formula [Chemical Formula 1], A is a carbazole group which may have a substituent, and R ⁶ and R ⁷
Is an aromatic hydrocarbon group, and the optical functional element having a memory property according to claim 3. 5. The compound having a memory-providing function is an aromatic halogen compound in which two or more chlorine atoms and / or bromine atoms are substituted.
An optical functional element having a memory property according to any one of 1. 6. The optical functional device having a memory property according to claim 1, wherein the compound having a memory property imparting function is a thioketone represented by the following chemical formula [Chemical formula 2]. .. [Chemical 2] (In the chemical formula [Chemical Formula 2], Ar ₁ and Ar ₂ represent an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent) 7. The electron-withdrawing compound having no memory-providing function has, as a substituent, any one of a nitro group, a cyano group, an acyloxy group, an alkoxycarbonyl group, a cyanovinyl group, a sulfonyl group, a sulfinyl group and a sulfonyloxy group. It is an aromatic compound which has one or more, The optical functional element which has a memory property in any one of Claims 1-6 characterized by the above-mentioned. 8. The optical function having a memory property according to claim 7, wherein the electron-withdrawing compound having no memory property imparting function is a dicyanovinyl compound represented by the following chemical formula [Chemical Formula 3]. element. [Chemical 3] (In the chemical formula [Chemical Formula 3], Ar ₃ is an aromatic hydrocarbon group which may have a substituent, X is an alkyl group or an aromatic hydrocarbon group which may have a substituent, P is 0, Represents an integer of 1 or 2) 9. The optical functional device having a memory property according to claim 1, wherein the binder polymer is a polyester resin, a polycarbonate resin, a methacrylic resin, an acrylic resin or a phenoxy resin.