JPH0654813B2 - Organic photoconductive device and manufacturing method thereof - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to organic photoconductive devices and methods of making the same, and more particularly to a photoconductive layer patterned into high photoconductive regions and low or non-photoconductive regions. And an organic photoconductive device and a manufacturing method for easily providing the organic photoconductive device.

(Prior Art) Conventionally, for example, various photoconductive media such as photoelectric conversion elements have been known, and in most cases, an inorganic material is used as a material of a functional portion of these photoconductive devices. However, as these photoconductive devices are required to have higher precision and higher miniaturization, the use of photoconductive organic compounds, which are easy to handle and have many types, as materials for functional parts of photoconductive devices has been widely studied. There is.

A photoconductive organic compound is known as one type of photoconductive substance, and there are various methods for forming such a photoconductive organic compound as a uniform film on an arbitrary substrate. As an example thereof, the Langmuir-Blodgett method (LB method) proposed by Langmuir et al. Is known.

According to this LB method, a monomolecular film of a photoconductive organic compound having a hydrophobic site and a hydrophilic site in one molecule or a cumulative film thereof can be easily formed on a substrate. The photoconductive organic layer formed in this way is good in the horizontal direction of the film because the hydrophobic part having a high electrical insulation property and the hydrophilic part having a high photoconductivity are superposed in a multi-layered manner in a plane. It exhibits unique photoconductivity and has a peculiar property of photoconductivity anisotropy that it has high insulation in the direction perpendicular to the film.

(Problems to be Solved by the Invention) The photoconductive organic layer as described above has very uniform photoconductivity in the plane direction of the layer, and various applications are expected. When a photoconductive device having these photoorganic conductive layers is used as various electric elements such as an electric circuit, it is necessary to finely process the photoconductive layers into a desired pattern. As such a microfabrication method, for example, a method of forming and growing a photoconductive layer as described above on a substrate in a pattern is considered, but the LB film as described above has a uniform pattern spread on the water phase. Since the monomolecular film is formed by the method of transferring it onto the substrate, the formation of such a patterned film has not yet reached a practical area.

As another method, a method of patterning the LB film once formed by post-treatment, for example, an etching method of removing a desired region of the film is considered, but this method is different from the chemical etching of the inorganic substance, There is a problem in that it is difficult to select a material, a mask method, an etching agent, and the like, and there is a great possibility that even the photoconductive layer other than the etching region is deteriorated by the etching agent. In particular, the higher the density and the degree of integration of the organic photoconductive device, the more difficult such fine processing becomes, and therefore, the excellent properties of the layer composed of the monomolecular film or the cumulative film of the organic photoconductive compound can be utilized. There is a problem that you can not.

The photoconductivity of the LB film as described above is usually 10 ^-10 to 1
Although it is very high as an organic substance of about 0 ^-14 S / cm, it is extremely small compared to the conventional inorganic photoconductive material, so that there is a problem that it is insufficient in terms of photoconductivity. .

Therefore, in a photoconductive device having a functional portion made of a photoconductive organic substance as described above, the photoconductivity of these layers is improved without impairing the characteristics of these layers, and a fine pattern can be easily formed with high accuracy. Technology is required.

(Means for Solving the Problems) As a result of earnest research to meet the above-mentioned demands of the prior art, the present inventor did not impair the precision and the characteristics of the photoconductive layer made of a photoconductive organic material. We have developed a technique that enhances the photoconductivity of these photoconductive layers and allows easy patterning of high photoconductive regions and low or non-photoconductive regions of a desired pattern.

That is, the present invention provides an optical film including a monomolecular film of a photoconductive organic compound having a hydrophobic site and a hydrophilic site in one molecule or a cumulative film thereof on the surface of a substrate having a fine uneven shape having an arbitrary directionality. An organic photoconductive device having a conductive organic layer formed and a method for manufacturing the same.

Next, the present invention will be described in more detail.

That is, according to a detailed study by the present inventor, when a photoconductive layer is formed of a photoconductive organic compound on a substrate having a smooth surface, a substantially uniform photoconductive layer is formed in a direction parallel to the surface of the photoconductive layer. However, by forming a fine concavo-convex shape having arbitrary directionality on the substrate surface in advance and forming a photoconductive layer on that surface, the concavo-convex pattern on the substrate can be obtained. The photo-conductivity of the photo-organic conductive layer formed on it along the shape is remarkably improved or lowered to be patterned into the high photo-conductive region and the low or non-photo-conductive region. there were.

Such a remarkable change in photoconductivity means that when the organic photoconductive layer is transferred to a fine uneven surface, the orientation of molecules constituting the layer is significantly improved along the uneven shape, and It is believed that the photoconductivity of the film changes due to local flow or rearrangement of film-constituting molecules depending on the uneven shape.

Therefore, at least the fine concavo-convex shape formed or provided on the substrate needs to have a certain directionality and be continuous or macroscopically continuous (for example, continuous broken lines).

According to the present invention, it is possible to form a desired photoconductive pattern by merely forming an organic photoconductive layer on the surface of the substrate by providing the substrate with a fine uneven shape having an arbitrary directionality. The present invention provides a photoconductive device, which easily solves various drawbacks in the prior art, that is, many complicated processes, use of severe conditions such as high temperature and high pressure, and use of various chemicals. The organic photoconductive device with high density and high integration has been provided by a very simple process.

As the photoconductive organic compound forming the photoconductive layer of the organic photoconductive device of the present invention, any conventionally known photoconductive organic compound can be used, but a preferable photoconductive organic compound is within one molecule. It is a dye compound having a hydrophilic site, a hydrophobic site and a dye site in the.

Further, it is considered that the molecular rearrangement at the time of film formation described above largely depends on the intermolecular force at this time, and therefore, it is desired that the molecule suitable for the present invention has a relatively large molecular weight.
However, the dye molecule usually has a molecular weight of 500 or more, which satisfies this. In fact, most dyes are known to interact with each other at a certain concentration or more to form an association state, and conventionally known organic dyes having both a hydrophilic moiety and a hydrophobic moiety are both preferable in the present invention. Can be used. Such preferable dyes are not limited to cyanine dyes, merocyanine dyes, phthalocyanine dyes, triphenylmethane dyes, azulene dyes and the like, and biomaterials such as chlorophyll, rhodamine, cytochrome and other dye proteins can also be used.

In the present invention, the preferred method for forming a photoconductive layer on the surface of a substrate having a fine uneven shape having an arbitrary direction using the photoconductive organic compound is LB described above.
Is the law.

In the LB method, for example, in a molecule having a structure having a hydrophilic site and a hydrophobic site in the molecule like the above-mentioned photoconductive organic compound, the balance between them (the amphipathic balance) is appropriately maintained. At this time, a molecule is a method of forming a monomolecular film or a cumulative film thereof by utilizing the fact that a hydrophilic group faces downward on a water surface to form a monomolecular layer.

The monolayer on the water surface has the characteristic of a two-dimensional system. When the molecules are scattered, the area A per molecule and the surface pressure π
The two-dimensional ideal gas equation, πA = kT, holds between and and becomes a “gas film”. Here, k is the Boltzmann constant and T is the absolute temperature. If A is made sufficiently small, intermolecular interaction will be strengthened, and a two-dimensional solid "condensed film (or solid film)" will be formed. The condensation film can be transferred layer by layer to the surface of any object having various materials and shapes such as glass and resin.

Specific methods include, for example, the following methods.

The desired photoconductive organic compound is chloroform, benzene,
Dissolve in a solvent such as acetonitrile.

Then, using a suitable apparatus as shown in FIG. 1 of the accompanying drawings,
A solution of the photoconductive organic compound is spread on the aqueous phase 1 to form the photoconductive organic compound on the film.

Next, a partition plate (or float) 3 is provided to prevent the spreading layer from freely diffusing over the water phase and spreading too much, limiting the spreading area to control the aggregation state of the membrane substance, and proportional to the aggregation state. The obtained surface pressure π is obtained. The partition plate 3 can be moved to reduce the development area to control the aggregated state of the membrane substances, gradually increase the surface pressure, and set the surface pressure π suitable for the production of the membrane. While maintaining this surface pressure, a clean clean substrate 2 is vertically raised or lowered to transfer the monomolecular film of the photoconductive organic compound onto the substrate 2. Such a monomolecular film is a film in which molecules are arranged in an orderly manner as schematically shown in FIG. 2a or 2b.

The monomolecular film of the photoconductive organic compound is produced as described above,
By repeating the above operation, the desired cumulative number of cumulative films is formed. In order to transfer the monomolecular film of the photoconductive organic compound onto the substrate, a method such as the horizontal dipping method, the rotating cylinder method or the like can be used in addition to the above-mentioned vertical dipping method.

The horizontal attachment method is a method of transferring the monomolecular film by horizontally contacting the substrate with the water surface, and the rotating cylinder method is a method of rotating the cylindrical substrate on the water surface to transfer the monomolecular film to the substrate surface. is there.

In the above-mentioned vertical dipping method, when the substrate whose surface is hydrophilic is pulled up from the water in the direction crossing the water surface, the monomolecular film of the photoconductive organic compound in which the hydrophilic group of the photoconductive organic compound faces the substrate is formed. Formed on top (Fig. 2b). When the substrate is moved up and down as described above, the monomolecular films are stacked one by one in each step to form a cumulative film. Since the directions of the film-forming molecules are opposite in the pulling up process and the dipping process, according to this method, a Y-type film in which the hydrophobic group and the hydrophobic group of the photoconductive organic compound face each other is formed between the layers of the monomolecular film ( (Fig. 3a). On the other hand, in the horizontal deposition method, a monomolecular film in which the hydrophobic groups of the photoconductive organic compound face the substrate is formed on the substrate (Fig. 2a). In this method, even if the monomolecular film is accumulated, there is no change in the direction of the film-forming molecules, and in all the layers, an X-type film in which the hydrophobic group faces the substrate side is formed (Fig. 3b). On the other hand, in all layers, the cumulative film with hydrophilic groups facing the substrate is Z
It is called the mold film (Fig. 3c).

The method of transferring the monomolecular film onto the substrate is not limited to the above method, and when a large-area substrate is used, a method of extruding the substrate from a roll into the aqueous phase may be employed. Further, the orientations of the hydrophilic group and the hydrophobic group described above to the substrate are in principle, and can be changed by surface treatment of the substrate.

As described above, the photoconductive layer composed of the monomolecular film of the photoconductive organic compound or a cumulative film thereof is formed on the substrate.

In the present invention, the substrate for forming the photoconductive organic layer comprising a monomolecular film of the photoconductive organic compound or a cumulative film thereof as described above may be any material such as metal, glass, ceramics and plastic materials, Furthermore, a biomaterial having extremely low heat resistance can also be used. A conductive material such as a metal can be used because, as described above, the monomolecular film or the cumulative film has a sufficient insulating property in the direction perpendicular to the film.

The substrate as described above may have any shape and is preferably a flat plate, but is not limited to a flat plate. That is, the present invention has an advantage that a film can be formed according to any shape of the surface of the substrate.

At least a part of the surface of the substrate as described above has a fine uneven shape having an arbitrary directionality, and such an uneven shape can be formed by any conventionally known method. For example, if the substrate is made of synthetic resin,
A method of transferring the uneven shape using a mold having a fine uneven surface having a desired arbitrary direction, and when the substrate is a metal or a ceramic, it is generally used in conventional printing plate technology and IC technology. Photo-etching method, a method of forming a photosensitive resin layer on the desired surface of the above-mentioned substrate or other substrate, exposing through a mask pattern and developing, and forming an uneven shape by the thickness of the photosensitive resin layer, etc. Any method can be used. Further, it is preferable that the uneven shape formed is continuous and directional, such as a linear shape, a curved shape or a combination thereof. Further, in these uneven shapes, particularly in the case of linear or curved uneven shapes, when the spacing between the lines, that is, the bitch width is too wide, the photoconductive organic layer of the photoconductive organic layer formed thereon is Since the difference hardly occurs, the pitch width thereof is preferably about 0.1 to 100 μm.

Further, the shapes of the concave and convex portions having the linear uneven shape as described above, that is, the shapes of the valleys and the peaks are not particularly limited. However, if the difference in height between them, that is, the depth of the groove is too shallow, the difference in photoconductivity as described above becomes small. Therefore, a depth of about 0.1 to 100 μm is generally preferable.

The photoconductive device of the present invention is provided by forming a photoconductive organic layer on the surface of a substrate having a fine uneven shape having an arbitrary direction as described above by the method as described above.
When the photoconductive organic compound used has a polymerizable group, the film strength can be remarkably improved by polymerizing and curing these films after forming the films as described above.

(Operation / Effect) According to the present invention as described above, only by adopting a substrate having a fine uneven shape having a desired directionality as a substrate of a conductive device, particularly high temperature, pressure, light, etc. can be applied to the organic photoconductive layer. Since the desired photoconductive pattern can be imparted without applying the harsh conditions of, and without using strong agents such as various acids, alkalis and organic solvents, the excellent characteristics of the photoconductive organic compound used can be obtained. Provided is a high-performance organic photoconductive device having high density and high degree of integration without any harm.

Further, according to the present invention, since it is not necessary to destroy the organic photoconductive layer on the substrate in forming the photoconductive pattern, it is possible to form an arbitrary photoconductive pattern without adversely affecting the organic photoconductive layer. As a result, it is possible to provide an organic photoconductive device having a high degree of fine processing and excellent electrical characteristics with good reproducibility.

From the above points, according to the present invention, the organic photoconductive device of the present invention can be greatly expected not only as a conventional high-density electric element but also as a bioelectronic element utilizing a living body.

Next, the present invention will be described more specifically with reference to examples.

Example 1 On a glass substrate, a photoresist material OMR (manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied and dried to a thickness of 1.5 μm.

Next, after exposing through a photomask having linear shadow portions of various thicknesses and developing, as shown in FIG. 4, the grooves 8 ((groove width 1.6 μm, depth It
1.5 μm, the distance between grooves is 1, 2, 5, 10, 20, 100
.mu.m). However, FIG. 4 shows one of them. Three layers of cadmium arachidate monolayers were accumulated on the entire surface of the substrate by the LB method to perform water treatment.

1 mg of the above azulene dye derivative (1) in benzene solvent
After dissolving at a concentration of / m, CdCl ₂ concentration adjusted to pH 6.8 with KHCO ₃ was 4 × 10 ⁻⁴ mol /, and the solution was developed on a water phase at a water temperature of 17 ° C.

After evaporating and removing the solvent benzene, the surface pressure is 20 mN / m
And a monomolecular film was formed. Constant surface pressure (20mN /
m), the above substrate was gently dipped in the direction crossing the water surface at a speed of 3 mm / min, and then gently pulled up at a speed of 3 mm / min to form a two-layer monomolecular film on the surface of the substrate. Accumulated. Repeating the above accumulation operation 5 times
An organic photoconductive device of the present invention in which 0 layer 10 was laminated was obtained.

As shown in FIG. 4, for the sample obtained as described above,
An electrode 11 is provided and a monochromatic light beam (500-9
As a result of measuring the photoconductivity σp under irradiation, the σp between any two points on the continuous groove has a maximum with respect to the incident light of 850 nm in any groove interval region. The value was 10 ^-11 to 10 ^-10 S / cm. On the other hand, σp between independent grooves is 10 ^-14 over the entire measured wavelength range.
It was S / cm or less, and it was revealed that high photoconductivity was obtained due to the substrate surface shape, and at the same time, extremely large photoconductivity anisotropy was obtained in the in-plane direction of the photoconductive layer. That is, a photoconductive device having a pattern according to the directionality of the uneven shape of the substrate was obtained. Although the groove is linear in this embodiment, it may be curved as long as it has directivity.

Comparative Example 1 In an example in which a smooth glass substrate is used by the same method as above, the photoconductivity between any two points is 10 ⁻¹³ S / cm.
It was about.

Examples 2 to 6 and Comparative Examples 2 to 6 Except that the cumulative number of monolayers in Example 1 was as shown in Table 1 below, the same as in Example 1 and Comparative Example 1, the present invention and When various organic photoconductive devices of Comparative Examples were prepared and the photoconductivity was measured in the same manner as in Example 1, the results shown in Table 1 below were obtained.

Examples 7 to 11 Various organic photoconductive devices of the present invention were obtained in the same manner as in Example 1 except that the dyes shown in Table 2 below were used instead of the dyes in Example 1. When the photoconductivity (S / cm) of these organic photoconductive devices was measured in the same manner as in Example 1, the results shown in Table 2 below were obtained. However, at this time, Examples 8, 9, 10
In order to improve the film-forming property, the ratio of dye molecules to 1: 3
A mixture of arachidic acid (C ₁₉ H ₃₉ COOH) at the ratio of was used as the film constituent material. Further, in Example 10, a mixture of dyes 5 and 6 was used so that the molar ratio was 1: 1.

Example 11 A resist material OMR is coated on a glass substrate (1.5 μm thick).
Then, a stripe-shaped groove (groove interval 200 μm, width 1.6 μm, depth 1.5 μm) was formed on the resist by photoetching. Using this substrate, 20 layers of monomolecular films were accumulated in the same manner as in Example 1 to obtain a photoconductive device of the present invention. Further, each pair of external connection electrodes facing each other in the groove direction was formed on each continuous groove, and one of the counter electrodes was used as a common electrode. The sample obtained as described above was irradiated with a semiconductor laser beam having a center wavelength of 870 nm (output 20 mw, beam diameter 20 μmφ) in the same manner as in Example 1, and the conductivity σ was measured. Σ was about 10 ^-10 S / cm when irradiated between electrodes, whereas σ was 10 ^-14 S / cm or less when no irradiation was performed or when irradiation was performed between adjacent electrodes. there were.
That is, it is shown that the above-mentioned photoconductive device is composed of a large number of photoelectric conversion elements having a desired shape, and the elements are sufficiently insulated.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a method for forming a photoconductive organic dye layer of the photoconductive device of the present invention. FIG. 2 is a schematic diagram of a monomolecular film, and FIG. 3 is a schematic diagram of a cumulative film.
FIG. 4 is a diagram schematically showing a cross section of the photoconductive device of the present invention. 1; Water phase, 2; Substrate, 3; Float, 4; Monomolecular film, 5; Cumulative film, 6; Hydrophilic part, 7: Hydrophobic part, 8: Recessed part, 9; Convex part, 10: Photoconductive Organic dye layer 11; electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenji Saito Kenji Saito 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Miya ▲ saki ▼ Toshihiko 3-30-2 Shimomaruko, Ota-ku, Tokyo No. Canon Inc. (72) Inventor Ken Eguchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) Reference JP-A-60-189753 (JP, A) US Patent 2599542 (US) , A)

Claims (4)

[Claims] 1. A light containing a monomolecular film of a photoconductive organic compound having a hydrophobic site and a hydrophilic site in one molecule or a cumulative film thereof on the surface of a substrate having a fine uneven shape having an arbitrary directionality. An organic photoconductive device having a conductive organic layer formed thereon. 2. The organic photoconductive device according to claim 1, wherein the photoconductive organic compound is a photoconductive organic dye. 3. The organic photoconductive device according to claim 2, wherein the photoconductive organic compound is selected from cyanine dyes, merocyanine dyes, phthalocyanine dyes, triphenylmethane dyes, azulene dyes and dye proteins. 4. A monomolecular film of a photoconductive organic compound having a hydrophobic site and a hydrophilic site in one molecule by the Langmuir-Blodgett method on the surface of a substrate having a fine uneven shape having an arbitrary direction or A method for manufacturing an organic photoconductive device, comprising stacking the accumulated films.