JPH09138413A - Controlling method of orientation of molecule and liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a large pretilt angle and to reduce dependence of the pretilt angle on the conditions such as baking temp. by using a thin film of a discotic liquid crystal to control the orientation of org. or inorg. molecules. SOLUTION: A discotic liquid crystal has such properties that it can be easily oriented when it is applied on various kinds of orienting films such as polyimide and heated over the temp. to change into the liquid crystal phase and that when the liquid crystal is rapidly cooled in this state, it is stably present in a glass state while maintaining its oriented state. The pretilt angle of a discotic liquid crystal is induced on only one orienting film. The tilt angle can be controlled by mixing two kinds of discotic liquid crystals as the main component or by using another org. compd. while using a discotic liquid crystal as the main component. As for the discotic liquid crystal to be mixed, an isomer having only a little difference such as the position of substituents are different may be used, or a liquid crystal having the central core structure or the side chain structure completely different from the main liquid crystal may be used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel molecular orientation control method using a thin film made of discotic liquid crystal, and more specifically, a molecular orientation control method in which the orientation of the liquid crystal is good and the pretilt angle can be freely set. And a liquid crystal display device using the same.

[0002]

2. Description of the Related Art A liquid crystal display element is an electro-optical device including a liquid crystal material whose optical characteristics are changed by an external electric field. For example, in a TN (twisted nematic) liquid crystal display device, a liquid crystal alignment film is provided on the surface of a solid substrate so that liquid crystal molecules have a certain alignment state with respect to the surface, and the surface is subjected to a treatment such as rubbing. Is being done. That is, the liquid crystal alignment film is prepared by forming a thin film of a polymer such as polyimide, polyvinyl alcohol or polyamide on a solid substrate such as a glass plate by spin coating, a printing method, a dipping method or the like and curing it, and then using a cloth or the like. It was obtained by rubbing in one direction, and the liquid crystal alignment film aligned the liquid crystal molecules in one direction. Among these polymers, polyvinyl alcohol is not practically used because of its poor heat resistance and moisture resistance. Practically, polyimide and polyamide are generally used.

[0003] These polymers are heated a) when two substrates are superposed and sealed, and the chemical and orientation are stable against this heating. b) It has no solubility or swelling property in the liquid crystal. c) It has high humidity resistance. d) High film forming property. This is because the above conditions are satisfied. It is also known that an inclined alignment film of liquid crystal molecules can be obtained by rubbing these polymer films.

Furthermore, for a large-sized display, a super twist birefringence effect (TJ Schee) having an excellent display content is provided.
ffer and J. Nehring Appl. P
hys. Lett. 45 (10), 1021 (198
4)) A display element (STN) has been developed. For the supertwisted birefringence effect, a nematic liquid crystal blended with a chiral agent which is an optically active substance is used. This is 180 compared to around 90 degrees of TN type liquid crystal molecules in the liquid crystal display element.
The twist is about 270 degrees, and the larger the twist angle, the better the viewing angle dependence. In order to increase the twist angle, it is necessary that the liquid crystal orientation tilt angle is large. Specifically, in order to obtain a twist angle of 240 to 270 degrees, the liquid crystal orientation tilt angle needs to be 5 degrees or more. Currently, from the viewpoint of heat resistance, chemical resistance, etc., a conventional polyimide orientation film is used. Liquid crystal display elements twisted up to 270 degrees have been put to practical use.

However, a polyimide film is generally first applied as a solution of polyamic acid on a substrate and is subjected to ring closure by heating. However, the film is colored during this heating and the appearance of the device and the light resistance of the film are impaired. . Further, in order to carry out the ring-closing reaction, it is necessary to heat at least 250 ° C. or more, which may cause deterioration of the plastic substrate or the color filter. Further, there is a problem that the adhesion to the glass substrate is not so strong.

Further, conventionally, as a means for increasing the tilt orientation angle (pretilt angle) of liquid crystal molecules, a method of forming an obliquely vapor-deposited film of silicon oxide or the like, a film of an organic polymer having a long chain (Japanese Patent Laid-Open No. 1-177514). JP-A-62-297819
Japanese Patent Application Laid-Open Publication No. 2003-242242), and the film is rubbed. However, since oblique vapor deposition of silicon oxide or the like is performed in a vacuum system, mass production cost is high, and there is a problem that mass productivity is poor because of batch processing. Further, the method of rubbing a film of an organic polymer or the like having an alkyl long chain has a problem that the liquid crystal tilt alignment angle (pretilt angle) is significantly changed depending on the rubbing method and the firing temperature. (JP-A-3-197927).

On the other hand, Japanese Unexamined Patent Publication No. 64-62616 discloses a random copolymer containing a polysiloxane compound and a polyaramid compound as an alignment film material having little dependence of the liquid crystal tilt alignment angle on the firing temperature. However, the feature of this alignment film is that the pretilt angle is small, and STN and a wide viewing angle T are required.
Since the FT-LCD requires a high pretilt angle, these pretilt angles are smaller and impractical.

[0008]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned conventional problems and to provide a liquid crystal having a large pretilt angle and a very small dependence of the pretilt angle depending on conditions such as firing temperature. It is to provide a display element. Further, it is an object of the present invention to provide a liquid crystal display device which can adjust the pretilt angle arbitrarily and has a wide viewing angle. Another object of the present invention is to provide a method of widely controlling molecular orientation, not limited to liquid crystal display elements.

[0009]

The present invention provides: (1) A method for controlling the orientation of organic or inorganic molecules using a thin film made of discotic liquid crystal exhibiting optical anisotropy. (2) The method for controlling molecular orientation according to (1) above, wherein the thin film is in a molecular orientation state of a discotic nematic liquid crystal phase. (3) The method for controlling the orientation of molecules according to (1) or (2) above, wherein the thin film is composed of at least a discotic liquid crystal mixture. (4) The method for controlling the orientation of molecules according to (1) to (3) above, wherein the thin film is composed of a mixture of at least a discotic liquid crystal and an organic compound other than the discotic liquid crystal. (5) The method for controlling molecular orientation according to (2) above, wherein the molecular orientation state of the discotic nematic liquid crystal phase of the thin film is fixed by photopolymerization. (6) A liquid crystal display device comprising at least one layer of an oriented inorganic or organic molecule obtained by the method for controlling the orientation of molecules according to any one of (1) to (5). Achieved by

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The discotic liquid crystal compound is characterized by having a discotic molecular portion in its mother nucleus. The disk-shaped morphological characteristics of the mother nucleus portion excluding the side chain portion can be expressed as follows for a hydrogen-substituted compound that is a prototype compound, for example. First, the size of the molecule is determined as follows. 1) Construct a nearly planar, preferably planar, molecular structure for the molecule. In this case, it is preferable to use the standard values according to the mixture of the orbits as the bond distance and the bond angle. Can be referenced. 2) Using the structure obtained in 1) above as an initial value, optimize the structure by the molecular orbital method or the molecular force field method. As the method, for example, Gaussian92, MOPAC93, CH
ARMm / QUANTA and MM3 are mentioned, and Gaussian92 is preferable. 3) The center of gravity of the structure obtained by the structure optimization is moved to the origin, and the coordinate axis is taken as the principal axis of inertia (the principal axis of the inertia tensor ellipsoid). 4) Give each atom a sphere defined by the van der Waals radius and describe the shape of the molecule. 5) The length in each coordinate axis direction is measured on the van der Waals surface, and each is designated as a, b, and c. When a disk-like form is defined using a, b, and c obtained by the above procedure, a ≧ b> c and a ≧ b ≧ a / 2,
Preferably, it can be expressed as a ≧ b> c and a ≧ b ≧ 0.7a. Typical examples of the discotic liquid crystal compound are, for example, Quarterly Chemistry Review No. 22
"Liquid Crystal Chemistry" Chapter 5, Chapter 10, Section 2 (published in 1994)
Academic Publishing Center), C.I. Destrade et al., Mol. Cryst. Liq. Cryst. 71
Vol. 111 (1981), B.I. Kohne et al., Angew. Chem. 96, 70 (198
4 years), J. M. J. Lehn et al. Che
m. Soc. Chem. Commun. , P. 1794 (1985); Zhang, J .; S. Moore
Et al., J. Am. Chem. Soc. , 116
Vol., P. 2655 (1994). For example, benzene derivative, triphenylene derivative, truxene derivative, phthalocyanine derivative, porphyrin derivative, anthracene derivative, azacrown derivative, cyclohexane derivative, β-diketone metal complex derivative, hexaethynylbenzene derivative, dibenzopyrene derivative, coronene derivative and phenylacetylene macro Cycle. In addition, “Chemical Review No. 15 New Aromatic Chemistry” edited by The Chemical Society of Japan (19
The cyclic compounds described in 1977, published by The University of Tokyo Press) and their electronic structures such as heteroatom substitution can be mentioned. Further, as in the case of the above-mentioned metal complex, a disc-shaped molecule may be formed by forming an aggregate of a plurality of molecules by hydrogen bonding or the like.

In addition to this, Chemistry Review Chapter 22 edited by The Chemical Society of Japan
Volume, Liquid Crystal Chemistry, pp. 135 (1994), which is a discotic liquid crystal of an organometallic complex. It is considered that they exhibit a discotic liquid crystalline behavior by arranging a metal atom in the center of the molecule and arranging the ligand so as to surround the metal on the same plane.

A discotic liquid crystal compound is formed by a structure in which a linear alkyl group, an alkoxy group, a substituted benzoyloxy group or the like is radially substituted as a side chain with these as the mother nucleus of the center of the molecule. The mother nucleus compound is preferably one which forms a discotic nematic phase, and particularly preferably triphenylene and truxene. As the side chain, for example, an alkyl group,
Examples thereof include an alkoxy group, an alkylthio group and an acyloxy group, and an aryl group or a heterocyclic group may be used in the side chain. In addition, C.I. Hansch, A .; Leo, R.A. W. T
by Aft, Chemical Review Magazine (Chem. Rev.)
1991, 91, 165-195 (American Chemical Society) may be substituted with a substituent,
Representative examples include an alkoxy group, an alkyl group, an alkoxycarbonyl group, and a halogen atom. Further, the side chain may have a functional group such as an ether group, an ester group, a carbonyl group, a thioether group, a sulfoxide group, a sulfonyl group or an amide group.

The discotic liquid crystal phase is generally composed of a columnar phase in which central cores of discotic molecules are piled up in a column by intermolecular force, a discotic nematic phase in which discotic molecules are randomly aggregated, and a chiral phase. It is known that it can be roughly divided into the discotic nematic phase. However, W. H. P by de jeu
physical properties of liq
uid crystalline materials
(1980 by Gordon and Break
H., Science Publishers), columnar phases are often found but discotic nematic phases are rarely found.

However, in order to actually apply this property to a liquid crystal alignment film, it is necessary to realize a state in which all molecules constituting the thin film are statistically aligned in one direction at room temperature on a single-sided support. preferable. In general, the discotic liquid crystal is composed of alignment regions (domains) having a specific directionality microscopically, like the liquid crystal composed of conventional rod-like molecules, and macroscopically showing optical anisotropy. Not shown, because of the property of forming a so-called multi-domain phase of light scattering,
In many cases, the thin film does not exhibit favorable surface alignment properties that can be used for a liquid crystal alignment film.

In this regard, among various discotic liquid crystals, a liquid crystal having a property of forming a discotic nematic liquid crystal phase is a truxene derivative,
Triphenylene derivatives and benzene derivatives having substituted phenylacetylene in the side chain, phenylacetylene-based macrocycles, and the like can be mentioned. Among them, the triphenylene derivatives are easy to synthesize and are advantageous for use as optical elements. Tick nematic phase is easily formed.

With respect to these discotic liquid crystal compounds, the present inventors have studied in detail the correspondence between the alignment state on various supports and the optical characteristics, and show that the discotic nematic liquid crystal phase has an optically uniaxial alignment. In addition to finding possible conditions, they also found that it is possible to control the tilt angle distribution of discotic liquid crystal molecules.

As disclosed in Japanese Patent Laid-Open No. 7-146409, this discotic liquid crystal is coated on various alignment films such as polyimide and is easily aligned by heating above a liquid crystal forming temperature, and its state is also maintained. By rapidly cooling with, the glass is stably present in a glass state while maintaining its orientation state. Furthermore, rod-shaped liquid crystal molecules can be aligned in one direction with a tilt angle induced at each interface between two alignment films such as a liquid crystal cell, but only one alignment film is used in discotic liquid crystals. Similar tilt angles are induced above.

This tilt angle control is performed in Japanese Patent Application No. 6-705.
As disclosed in No. 91, the tilt angle can be controlled by using a mixture of two or more kinds of discotic liquid crystal as the main component, or by mixing another organic compound having the discotic liquid crystal as the main component. The discotic liquid crystal to be mixed may be a mixture of different positional isomers having different substituent positions or a mixture of completely different central nucleus structures and side chain structures. That is, DLC-No. Of the specific compound examples of the present invention shown below. 1 to DLC
-No. Mixtures of two of the compounds described in 78 are mentioned. Mixing examples other than the discotic liquid crystal may be liquid crystal compounds, non-liquid crystal compounds, polymerizable compounds, or non-polymerizable compounds, and any one of CNC-1 to CNC of specific compound examples of the present invention shown below may be used. The compounds described in -10 are preferably used.

At this time, the discotic liquid crystal is fixed by, for example, intermolecular hydrogen bonding, intermolecular thermal polymerization, polycondensation, or photopolymerization to improve heat resistance, moisture resistance, and chemical resistance. Further utilization of surface orientation has become possible. That is, the surface molecules of the discotic liquid crystal thin film thus formed can change the inclination angle of the optical axis in various ways, and if the surface is further used as an alignment film for liquid crystal, monodomain alignment is easily achieved, It was also found that the tilt angle can be expressed as a corresponding pretilt angle.

Examples of the substituent which can be polymerized by applying light or heat energy according to the present invention include S.I. R. Sandler and W.D. Kalow (SR Sandler,
W. Karo), Organic Functional
Group Preparations (Organic Fu
nctional Group Preparation
ns) The substituents described in Volumes 1 and 2 (Academic Press, New York, London, 1968) can be mentioned. Of these, a multiple bond (the constituent atom may be either a carbon atom or a non-carbon atom) and a small ring (eg, oxirane, aziridine), and more preferably R.I. A. M. Research report by Hikmet et al. [Macromolecules, 25, 41
94 (1992)] and [Polymer, 34.
Vol. 8, p. 1736 (1993)], D.M. J. Br
Oer et al.'s research report [Macromolecules,
26, 1244 (1993)], that is, a double bond, that is, an acrylic group, a vinyl ether group and an epoxy group.

The polymerization process used in the present invention is generally carried out after the liquid crystal exhibits preferable optical anisotropy, that is, after the monodomain is uniaxially aligned by heating on the alignment film. In the case of an epoxy group, cationic type polymerization by ultraviolet rays is also possible, but after orientation in a short time, the temperature can be further raised by several tens of degrees and fixed by thermal polymerization. However, radical polymerization or cationic polymerization using a photopolymerization initiator with ultraviolet rays generally has a very high polymerization rate and is preferable in terms of productivity in the manufacturing process.

Examples of the photopolymerization initiator in the present invention include US Pat. Nos. 2,367,661 and 2,367,67.
No. 0 α-carbonyl compounds described in each specification,
Acyloin ethers described in US Pat. No. 2,448,828, US Pat. No. 2,722,512
.Alpha.-hydrocarbon substituted aromatic acyloin compounds described in U.S. Pat. No. 3,046,127.
No. 2,951,758, a polynuclear quinone compound, a combination of a triarylimidazole dimer / p-aminophenyl ketone described in US Pat. No. 3,549,367, JP-A-6
0-105667, acridine and phenazine compounds described in US Pat. No. 4,239,850, oxadiazole compounds described in US Pat. No. 4,212,970, and the like. . The content concentration of these photopolymerization initiator systems in the composition of the present invention is usually low, and when the content is inappropriately high, undesired results such as blocking of effective rays are produced. The amount of photoinitiator system in the present invention is 0.
The range of 01% to 20% is sufficient, and more preferably 0.5% to 5% to obtain good results.

For the polymerization of the epoxy group, an allyldiazonium salt (hexafluorophosphate, tetrafluoroborate), a diallyliodonium salt, a Vb group allylonium salt (PF ₆ , As) is used as a UV-activated cation catalyst.
An allylsulfonium salt having an anion such as F ₆ or SbF ₆ ) is preferably used.

As the light rays for polymerization, electron rays, ultraviolet rays, visible rays and infrared rays (heat rays) can be used as required, but ultraviolet rays are generally used. The light sources include low-pressure mercury lamps (germicidal lamps, fluorescent chemical lamps, black lights), high-pressure discharge lamps (high-pressure mercury lamps, metal halide lamps), and short arc discharge lamps (ultra-high-pressure mercury lamps, xenon lamps, and mercury xenon lamps). No.

Specific examples of the compound used in the present invention are shown below, but the present invention is not limited thereto.

[0026]

Embedded image

[0027]

Embedded image

[0028]

Embedded image

[0029]

Embedded image

[0030]

Embedded image

[0031]

[Chemical 6]

[0032]

Embedded image

The structural examples of the compound used by mixing with the compound of the present invention are shown below.

[0034]

Embedded image

As the film for aligning the discotic liquid crystal, either an inorganic or organic alignment film can be used. As the metal oblique deposition film, the SiO oblique deposition film,
A typical example of the organic alignment film is a rubbed polyimide film, but other rubbed modified Poval, a rubbed silylating agent-treated glass substrate, or a rubbed gelatin film is also used. But,
Instead of rubbing, use a thin film of polyvinyl alcohol.
It is also possible to use a method in which the glass substrate is stretched 5 times to 5 times, or the glass substrate is directly rubbed without providing the above protective film.

Magnetic field orientation and electric field orientation are available as methods other than the above in which the discotic liquid crystal coated on the substrate is oriented obliquely. The liquid crystal layer constituting the optically anisotropic material of the present invention can be formed as a thin film on the support by a coating method such as a vapor deposition method, spin coating, dip coating, or extrusion coating.

Therefore, the liquid crystal thin film is formed on a suitable support in a state where at least one interface is in contact with the gas phase, that is, by a general coating method, and after drying, the disc liquid is formed at a temperature within the liquid crystal phase forming temperature range. Tick nematic phase or uniaxial columnar phase is formed and heat-treated for a certain period of time, and then it is directly subjected to thermal polymerization or photocrosslinking polymerization and then cooled to have a desired pretilt angle and high thermal durability. A liquid crystal alignment film can be obtained. This alignment film is
One of the features is that there are few alignment defects due to dust because the organic compound is applied after rubbing.

The molecule whose orientation is controlled is not particularly limited. For example, quarterly chemistry review No. No. 22. All of the liquid crystals described in "Chemistry of Liquid Crystals", and include nematic liquid crystals, smectic liquid crystals, cholesteric liquid crystals, discotic liquid crystals and the like. Further, cyanine dyes, merocyanine dyes, porphyrin-based dyes, and phthalocyanine-based dyes known as associative molecules are also included. In addition, the amphipathic molecules forming the Langmuir-Blodgett film and the conventionally deposited organic / inorganic molecules can induce the orientation or tilt angle with further anisotropy.

After the formation of the molecular layer or the aggregate layer thereof, the alignment control film derived from the discotic liquid crystal used for controlling the alignment may be peeled off and used.

The molecular orientation control film of the present invention comprises TN liquid crystal and S
It can be used as a substitute for any of the alignment films that are practically used as liquid crystal display devices such as TN liquid crystal and FLC liquid crystal at present. Particularly effective when a large tilt angle is required

[0041]

EXAMPLES Hereinafter, preparation of a liquid crystal alignment film by photopolymerization of a composition containing a liquid crystal compound of the present invention and performance evaluation thereof will be described.

Example 1 (Preparation of Liquid Crystal Alignment Film by Heating Alignment / Photopolymerization of Liquid Crystalline Compound) A glass slide for microscope (S-7213 manufactured by MATSUNAMI Co., Ltd., size 76 mm × 26 mm) was used as a substrate, and acrylate was formed thereon. Applying a modified terminal alkyl PVA,
After drying with 90 ° C. hot air, rubbing treatment was performed to form an alignment film. DLC-1, 1.82 is formed on this alignment film.
g, trimethylolpropane EO-modified triacrylate (V # 360 Osaka Organic Chemical Industry Co., Ltd.) 0.18 g, cellulose acetate butyrate (CAB551-0.2)
Eastman Chemical) 0.04 g, photopolymerization initiator (Irgacure-907 Ciba Geigy) 0.06 g, sensitizer (Kayacure-DETX Nippon Kayaku Co., Ltd.) 0.02
The coating solution prepared by dissolving 15 g of methyl ethyl ketone in 15.93 g is applied with a wire bar, and the solution is kept in a constant temperature bath at 120 ° C. for 3 times.
After heating for 1 minute to align the discotic liquid crystal, 1
The operation of UV irradiation for 1 second using a 120 W / cm high pressure mercury lamp at 20 ° C. and cooling to room temperature was repeated to obtain 4 glass substrates with a liquid crystal alignment film of the present invention.

Two cells of the above glass substrates were assembled with the spacers of 20 microns sandwiched so that the coating directions were opposite to each other, and nematic liquid crystal (Merck)
ZLI1565) was injected and the liquid crystal tilt alignment angle was measured and found to be 29 degrees. In addition, the remaining two glass substrates were heated in a constant temperature bath at 200 ° C for 4 days, allowed to cool, and then coated with a 20-micron spacer so that the coating directions were opposite to each other. After assembling, nematic liquid crystal (ZLI1565 manufactured by Merck & Co., Inc.) was injected and the liquid crystal tilt alignment angle was measured, but it was 28.5 degrees, almost no change was observed, and this film had strong thermal durability. I found out that

Example 2 A microscope slide glass (S-7213 manufactured by MATSUNAMI Co., Ltd., size 76 mm × 26 mm) was used as a substrate, on which an acrylate-modified terminal alkyl PVA was coated.
After drying with 90 ° C. hot air, rubbing treatment was performed to form an alignment film. DLC-1, 1.82 is formed on this alignment film.
g, trimethylolpropane EO-modified triacrylate (V # 360 Osaka Organic Chemical Industry Co., Ltd.) 0.03 g, cellulose acetate butyrate (CAB551-0.2)
Eastman Chemical) 0.04 g, photopolymerization initiator (Irgacure-907 Ciba Geigy) 0.06 g, sensitizer (Kayacure-DETX Nippon Kayaku Co., Ltd.) 0.02
The coating liquid prepared by dissolving g in 5.86 g of methyl ethyl ketone was applied with a wire bar and heated in a constant temperature bath at 148 ° C. for 8 minutes to align the discotic liquid crystal, and then 14
The operation of irradiating UV with a 120 W / cm high-pressure mercury lamp for 1 second at 8 ° C. and allowing to cool to room temperature was repeated to obtain two glass substrates with a liquid crystal alignment film of the present invention.

Two cells of the above-mentioned glass substrates were assembled with the spacers of 20 microns sandwiched so that the coating directions were opposite to each other, and nematic liquid crystal (Merck)
ZLI1565) was injected and the liquid crystal tilt alignment angle was measured and found to be 16 degrees.

Comparative Example A microscope slide glass (S-7213 manufactured by MATSUNAMI Co., Ltd., size 76 mm × 26 mm) was used as a substrate,
A gelatin subbing layer having a thickness of 0.1 μm is provided, and a polyamic acid (SE-721 manufactured by Nissan Chemical Industries, Ltd.) is used as an alignment film on the undercoat layer.
0) was applied and baked at 180 ° C. to form a polyimide film. The above operation for imparting alignment ability by rubbing this polyimide film with a rubbing machine was repeated to obtain two glass substrates with a liquid crystal alignment film. When two cells of the above-mentioned glass substrates were assembled so that the coating directions were opposite to each other with a 20-micron spacer interposed therebetween, nematic liquid crystal (ZLI1565 manufactured by Merck & Co., Inc.) was injected, and the liquid crystal tilt alignment angle was measured. It was 4.3 degrees.

[0047]

From the above examples, the thin film obtained by the method of the present invention has excellent thermal durability as a liquid crystal alignment film, and can be achieved by the conventional alignment film by changing the discotic liquid crystal composition. Since a difficult high pretilt angle can be easily exhibited, it can be suitably used for an SBE display element, a ferroelectric display element and an antiferroelectric display element by selecting a liquid crystal to be used.

Claims (6)

[Claims] 1. A method for controlling the orientation of organic or inorganic molecules using a thin film made of discotic liquid crystal exhibiting optical anisotropy. 2. The method for controlling molecular orientation according to claim 1, wherein the thin film is in a molecular orientation state of a discotic nematic liquid crystal phase. 3. The method for controlling the orientation of molecules according to claim 1, wherein the thin film is composed of a mixture of at least discotic liquid crystals. 4. The method for controlling the orientation of molecules according to claim 1, wherein the thin film comprises a mixture of at least a discotic liquid crystal and an organic compound other than the discotic liquid crystal. 5. The method for controlling molecular orientation according to claim 2, wherein the molecular orientation state of the discotic nematic liquid crystal phase of the thin film is fixed by photopolymerization. 6. A liquid crystal display device comprising at least one layer of an inorganic or organic molecule oriented film obtained by the method for controlling the orientation of molecules according to claim 1.