JP2006021976A - Method and apparatus for manufacturing thin film-like organic single crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a thin film-like organic single crystal by which a large size, high quality organic single crystal 6 can be manufactured with a desired thickness by a solvent evaporation method even when the organic material is unstable to heat or the like and cannot be crystallized by a melt method, and to provide an apparatus for manufacturing the thin film-like organic single crystal 6 which is suitable for manufacturing the large size, high quality organic single crystal 6 having a desired thickness. <P>SOLUTION: The method for manufacturing the thin film-like organic single crystal comprises filling a solution 5, obtained by dissolving an organic substance to be crystallized in a solvent, into a gap formed by a couple of substrates 4a, 4b, and then forming the organic single crystal 6 by controlling the evaporation speed of the solvent from the couple of substrates 4a, 4b between which the solution 5 is filled. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for producing a thin-film organic single crystal using a solvent evaporation method in which a thin-film organic single crystal used for a nonlinear optical material, an electronic material, a light-emitting material, or the like is formed on a substrate. .

  In recent years, it has been clarified that organic materials have superior electrical and optical properties compared to inorganic materials. Thermal conductive materials, EL (electroluminescence) materials, PHB (photochemical hole burning) materials, photochromic materials Application development in fields such as nonlinear optical materials has been actively promoted. In particular, when organic materials are used as nonlinear optical materials, it has been found that a large nonlinear optical constant is obtained compared to inorganic materials and that high-speed response is excellent. Optical wavelength conversion bulk single crystal using nonlinear optical effect, optical wavelength conversion element, optical modulator, optical bistable element, optical shutter, optical phase conjugate element using third-order nonlinear optical effect of organic materials, etc. Development of various non-linear optical elements has been actively promoted.

  Conventionally, methods for producing single crystals of organic materials include dry methods such as vacuum deposition and molecular beam epitaxy (MBE), solvent evaporation, melt methods, Langmuir-Blodget (LB), and the like. A wet method is used.

  The dry method is excellent in uniformity and controllability of the film thickness, but organic materials generally have a low thermal decomposition point and are decomposed by heat. Therefore, usable materials are very limited.

  In the wet method, the organic material is heated to the melting point to form a liquid, then cooled and crystallized, and the organic material is completely dissolved in a soluble solvent, and then the saturation concentration of the solute is controlled. Thus, a solution method for crystallization is used.

  The melt method has been reported to date, but it is necessary to raise the temperature to the melting point of the organic material, so it cannot be used with materials that may be sublimated or decomposed by heat, so the materials that can be used are limited. Has been.

  In the solution method, a slow cooling method, a solvent evaporation method or the like is generally used as a method for producing a bulk single crystal.

  In the slow cooling method, the temperature of an unsaturated solution is controlled (cooled) to bring it into a saturated state (a supersaturated state depending on the material) to precipitate crystals. In the solvent evaporation method, the solution is saturated by the evaporation of the solvent (a supersaturated state depending on the material) to precipitate crystals.

  For organic single crystals, various manufacturing methods as described above have been proposed. However, in consideration of actual application, it is difficult to use the deposited crystal shapes as they are. In particular, when used as an optical element, the planarity of the surface state often becomes a problem, and thus processing by polishing, grinding, or the like is necessary after crystal production.

  However, in the case of organic crystals, the hardness is generally low, and processing problems such as cracks and chipping occur. Therefore, Patent Document 1 reports that crystals are grown in a thin film form in advance. However, it is an application of the melt method, and as described above, it cannot be used with organic materials that decompose near the melting point, and the materials are limited.

Meanwhile, 4-dimethylamino-N-methyl-4-stilbazolium tosylate (hereinafter referred to as “DAST”) shown in FIG. Developed in the Nakanishi Laboratory of Tohoku University, it has extremely large nonlinear optical constants and electro-optical constants, and has a low dielectric constant unique to organic crystals. ing. The electro-optic constants of DAST are r ₁₁ = 53 “pm / V” (1.3 μm), 92 “pm / V” (720 nm) and LiNbO ₃ r ₃₃ = 30.8 “pm / V” (633 nm). Big in comparison. Since the dielectric constant of DAST is ε ₁₁ = 5.2, which is smaller than that of LiNbO ₃ 28, there is a possibility of high-speed and low-voltage optical modulation in the optical modulator. The transmission characteristic of DAST is substantially flat at 0.8 to 1.6 μm, and is a material suitable for an optical communication wavelength band device.

  Regarding the production of DAST crystals, many reports have been made on the production method of bulk crystals from solution (solution method) by the Sasaki Laboratory of Osaka University (for example, Patent Document 2).

  However, since the crystal shape is not controlled, it is very difficult to apply the obtained crystal without processing. Further, in the bulk crystal production method from a solution, it is extremely difficult to arbitrarily control the crystal thickness (crystal shape) by a temperature parameter or the like.

For the preparation of DAST thin film crystals, see M.M. Non-Patent Document 1 reports a thin film crystal having a thickness of 3 to 4 μm and 1 cm ² using the improved shear method.

  However, since the improved shear method described in Non-Patent Document 1 is controlled only by weight without using a spacer, the thickness of the crystal can be controlled only in a relatively thin direction of about several microns.

Furthermore, P.I. Gunter et al. Have reported that DAST has a melting point (about 260 ° C.) and a thermal decomposition point (about 290 ° C.), so that thermal decomposition occurs near the melting point and contains many impurities. It is known that single crystals cannot be produced using a liquid method.
JP-A-6-186600 JP 2002-29899 A M.M. Thaku APPLIED PHYSICS LETTERS, vol. 74 (1999) 635

  As described above, there has been no report that a DAST crystal is controlled to an arbitrary thickness and a thin film single crystal is produced.

  The present invention has been made in view of the above points. The object of the present invention is that any organic material that is unstable to heat and cannot be crystallized by the melt method can be obtained by the solvent evaporation method. A method for producing a thin-film organic single crystal capable of producing a thick, large, and high-quality organic single crystal is provided, and a thin-film organic single crystal having an arbitrary thickness and suitable for producing a large-scale, high-quality organic single crystal. The object is to provide a crystal manufacturing apparatus, and further to provide a thin-film organic single crystal manufacturing method and manufacturing apparatus for manufacturing a DAST organic single crystal.

  As a result of repeating various studies to achieve the above-mentioned object, the present inventors filled a gap formed by a pair of substrates with a solution obtained by dissolving an organic substance to be crystallized in a solvent, The inventors have found that the above-mentioned problems can be achieved by controlling the rate at which the solvent is evaporated, and have reached the present invention.

  That is, in the method for producing a thin-film organic single crystal according to claim 1, after filling a gap formed by a pair of substrates with a solution obtained by dissolving an organic substance to be crystallized in a solvent, The organic single crystal is manufactured by controlling the rate of evaporation of the solvent from the pair of filled substrates.

  The method for producing a thin-film organic single crystal according to claim 2 is the invention according to claim 1, wherein the solvent evaporation rate is controlled in a production container capable of sealing a pair of substrates filled with the solution. After the installation, the additive gas is introduced into the production container from a gas storage container containing an additive gas containing a certain amount of vapor of the solvent.

  The method for producing a thin-film organic single crystal according to claim 3 is the invention according to claim 2, wherein the rate of evaporation of the solvent is controlled at different temperatures in the production container and the gas storage container. It is characterized by being performed.

  The method for producing a thin-film organic single crystal according to claim 4 is the invention according to claim 2 or 3, wherein the rate of evaporation of the solvent is controlled by evaporating the solvent until saturated. After the inside is saturated with the solvent vapor, a pair of substrates filled with the solution is placed in a sealable manufacturing container.

  The thin-film organic single crystal manufacturing method according to claim 5 is the invention according to any one of claims 1 to 4, wherein the gap is formed by installing a spacer between the pair of substrates. It is characterized by.

  The method for producing a thin-film organic single crystal according to claim 6 is the invention according to any one of claims 1 to 5, wherein the organic substance is 4-dimethylamino-N-methyl-4-stilbazo. It is characterized by being lithium tosylate.

  The thin-film organic single crystal manufacturing apparatus according to claim 7 includes a gas introduction port for introducing a gas, an introduction gas flow valve for adjusting a flow rate of the gas introduced from the gas introduction port, and a gas discharge port for discharging the gas. And a sealable production container provided with an exhaust gas flow valve for adjusting the flow rate of the gas discharged from the gas discharge port, and a fixed solvent of a solvent that is connected to the gas inlet and dissolves the organic substance to be crystallized. An apparatus for producing a thin-film organic single crystal having a gas storage container containing an additive gas containing a vapor amount, wherein the inside of the preparation container and the inside of the gas storage container can be controlled at different temperatures. It is characterized by that.

  According to the first aspect of the present invention, even in an organic material that cannot be used by the melt method due to thermal decomposition or the like, the solvent evaporation amount is controlled in the solution evaporation method, so that the substrate is stably large and high quality. A thin film-like organic single crystal can be produced.

  According to the second aspect of the present invention, the amount of evaporation of the solvent can be controlled by introducing a gas containing a certain amount of vapor of the solvent into the production container in which the pair of substrates filled with the solution is installed. A large-scale and high-quality thin-film organic single crystal can be produced stably on the substrate.

  According to the invention of claim 3, the temperature in the fabrication container in which the pair of substrates is arranged and the temperature in the gas storage container storing the gas containing a certain amount of vapor of the solvent are controlled to different temperatures. By doing so, it is possible to produce a gas containing less solvent vapor than in the production container, and it is possible to control the amount of evaporation of the solvent more easily, and it is stable and large in size on the substrate A thin film-like single crystal can be produced.

  According to the invention of claim 4, after the inside of the production container is saturated with a solvent, the pair of substrates filled with the solution are placed in a production container that can be sealed, so that the first time when the single crystal is produced It becomes possible to moderate the evaporation of the solvent, suppress the polycrystallization due to the rapid evaporation of the solvent, and produce a large-scale and high-quality thin-film single crystal on the substrate more stably.

  According to invention of Claim 5, the thickness of a thin film-like single crystal can be arbitrarily adjusted by installing a spacer between a pair of board | substrates and forming a clearance gap.

  According to the invention described in claim 6, since the organic substance to be crystallized is 4-dimethylamino-N-methyl-4-stilbazolium tosylate, it has extremely large nonlinear optical constants and electro-optical constants. It is possible to produce a DAST thin film single crystal that has a low dielectric constant peculiar to organic crystals and can be developed for low voltage, high-speed optical modulation, detection, millimeter wave generation, and the like.

  According to the seventh aspect of the present invention, since the inside of the sealable production container and the gas storage container can be controlled at different temperatures, the evaporation amount of the solvent that evaporates from the gap between the pair of substrates Can be stably controlled, and as a result, a large-sized and high-quality thin-film organic single crystal can be stably formed on the substrate.

  The method for producing a thin film-like organic single crystal of the present invention includes a solution obtained by dissolving an organic substance to be crystallized in a gap formed by a pair of substrates in “preparing an organic single crystal by a solvent evaporation method” in a solvent. After filling, a thin film organic single crystal is produced by controlling the rate of evaporation of the solvent from the pair of substrates filled with the solution.

  By producing a single crystal with a gap formed by a pair of substrates, the thickness of the obtained single crystal becomes the distance between the gaps formed by the pair of substrates, and the planarity is also improved. In addition, by controlling the evaporation rate of the solvent, it is possible to efficiently produce a large-scale and high-quality thin-film single crystal by suppressing polycrystallization due to rapid evaporation (rapid increase in supersaturation degree).

  As the pair of substrates, a quartz substrate, a resin substrate such as polyimide or polyethylene, glass, silicon, or the like can be used, but a quartz substrate is preferable from the viewpoint of the effects of the invention. The surface shape of the pair of substrates is not particularly limited, and may be, for example, a circle, a rectangle, or an ellipse.

  The distance between the gaps formed by the pair of substrates can be arbitrarily determined and is not particularly limited. However, considering application to an optical device such as an optical modulator, 0.1 to 1000 μm is preferable. 0 μm to 100 μm is more preferable.

As the organic substance, any organic material having a large nonlinear optical constant as compared with inorganic materials such as KH ₂ PO ₄ and LiNbO _{3 that} have been used in the past can be used. For example, 4-dimethylamino-N— Methyl-4-stilbazolium tosylate (DAST), 2-methyl-4-nitroaniline (MNA), metanitroaniline (mNA), 3-methyl-4-nitropyridine-1-oxide (POM), urea 2-methyl-3-cyano-2- (2-methoxyphenyl) -2-propenoate (CMP methyl), L-arginine phosphate monohydrate (LAP), 4- (N, N dimethylamino) -3-acetamidonitrobenzene (DAN), 3,5-dimethyl-1- (4-nitrophenyl) pyrazole (DMNP) and the like. Here, 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) has an extremely large nonlinear optical constant and electro-optical constant and has a low dielectric constant peculiar to organic crystals. It is preferable.

  As the solvent, for example, methanol, ethanol, 1-propanol, 2-propanol, acetone, 2-butanone, chloroform, dichloromethane, 1,2-dichloroethane, dimethyl ether, ethyl acetate, hexane, cyclohexane, acetonitrile, toluene and the like are used. However, methanol is preferable because it is highly volatile, inexpensive, and easily available.

  The method of filling the gap with the solution is not particularly limited, and may be filled with the solution using a capillary phenomenon or the like, or may be appropriately filled with the solution using an injection means.

  Control of the rate at which the solvent is evaporated from the pair of substrates filled with the solution is performed after the pair of substrates filled with the solution is placed in a sealable manufacturing container, and then an additive gas containing a certain amount of solvent vapor is stored. It is preferable to introduce the additive gas from the gas storage container into the production container. By flowing an additive gas containing a certain amount of solvent vapor into the production vessel, the rate of the solvent evaporating from the gap between the pair of substrates can be made constant, and polycrystallization due to a rapid change in evaporation rate This is because it is possible to efficiently produce a large-sized and high-quality thin-film single crystal while suppressing deterioration in quality.

  Regarding crystal growth that occurs as a result of evaporating the solvent from the solution filled in the gap between the pair of substrates, if the solvent is rapidly evaporated from the solution, many crystals will precipitate in a short time. Does not grow large and becomes a polycrystalline state, or a problem occurs such that the solvent is taken into the crystal and becomes a defect, but by slowly evaporating the solvent, the number of crystals can be reduced and increased. It becomes.

  For example, filling a gap between a pair of substrates in a case where an additive gas containing a certain amount of solvent vapor and nitrogen gas is allowed to flow into the fabrication vessel is more effective than when only normal nitrogen gas is allowed to flow in the fabrication vessel. It is possible to slow down the evaporation rate of the solvent from the prepared solution and to control the evaporation amount of the solvent.

  The constant vapor amount of the solvent here does not necessarily need to be a saturated vapor of the solvent, and it is only necessary to be able to control the amount of the solvent evaporated from the solution filled in the gap between the pair of substrates. It may be a certain amount of vapor that is less than the saturated vapor amount of the solvent inside. The constant vapor amount of the solvent mentioned here is more preferably a vapor amount in the vicinity of the saturated vapor of the solvent from the viewpoint of very good control of the evaporation amount of the solvent, and further, if the saturated vapor of the solvent, preferable.

  As the additive gas containing a certain amount of vapor of the solvent, for example, a mixed gas of a certain amount of vapor of the solvent and nitrogen gas is suitable, but if the organic substance is not denatured, nitrogen gas can be used instead of nitrogen gas or nitrogen gas. Other gases can be used in addition to the gas.

  More preferably, the rate at which the solvent is evaporated from the pair of substrates filled with the solution is controlled by controlling the inside of the production container and the inside of the gas storage container at different temperatures. By controlling the temperature in the production container in which the pair of substrates are arranged and the temperature in the gas storage container containing the additive gas containing a certain amount of solvent vapor to different temperatures, the amount of solvent vapor in the production container A small amount of solvent vapor can be easily and reliably realized, the evaporation rate of the solvent can be accurately controlled, and a large-scale and high-quality thin-film organic single crystal can be efficiently produced. It is.

  Examples of the method for controlling the temperature inside the production container and the gas storage container to different temperatures include temperature control using a thermostatic bath, temperature control using a sheet-type heater, and the like. It is possible to use.

  Control of the rate of evaporation of the solvent from the pair of substrates filled with the solution is achieved by evaporating the solvent until saturation is reached, and after the inside of the production container is saturated with solvent vapor, the pair of substrates filled with the solution is sealed. More preferably, it is placed in a possible production container. At the time of crystal production, the inside of the production container is saturated with solvent vapor at the stage before placing the pair of substrates filled with the solution obtained by dissolving the organic substance to be crystallized in the production container in the solvent. This is because the first solvent evaporation can be moderated, and polycrystallization due to rapid solvent evaporation can be suppressed, and a large-sized and high-quality thin-film organic single crystal can be produced more efficiently.

  The gap formed by the pair of substrates is preferably formed by installing a spacer between the pair of substrates. This is because by installing a spacer between the pair of substrates, the thickness of the thin film-like single crystal to be manufactured can be freely changed, and an arbitrary thickness can be obtained.

  The spacer is not particularly limited as long as it is not altered by the solution filled in the gap. Examples of the spacer include polyethylene terephthalate (PET) film, polytetrafluoroethylene (PTFE), perfluoroalkoxyethylene resin (PFA), polycarbonate (PC), polyvinyl alcohol (PVA), polymethyl methacrylate (PMMA), and polystyrene. , Polysulfone (PSF), polyethersulfone (PES), polyimide and the like.

  The thin-film organic single crystal production apparatus of the present invention includes a gas introduction port for introducing a gas, an introduction gas flow valve for adjusting the flow rate of the gas introduced from the gas introduction port, a gas discharge port and a gas exhaust for discharging the gas. A sealable production vessel with an exhaust gas flow valve that regulates the flow rate of gas discharged from the outlet, and an addition that includes a certain amount of vapor connected to the gas inlet and that dissolves the organic material to be crystallized. It has a gas storage container that stores gas, and is configured to be able to control the inside of the production container and the inside of the gas storage container at different temperatures. The thin-film organic single crystal manufacturing apparatus of the present invention can provide a large-sized and high-quality thin-film organic single crystal manufacturing apparatus.

Example 1
First, the container 3 containing methanol (solvent) is placed in the production container 1, the introduction gas flow valve 8 at the gas introduction port of the production container 1 and the exhaust gas flow valve 9 at the gas discharge port are closed, and production is performed. The inside of the container 1 was kept at 20 ° C. in a thermostatic bath for 2 hours, and the inside of the production container 1 was saturated with methanol vapor (FIG. 1-1).

  Separately, two circular quartz substrates having a diameter of 100 mm are prepared, the pair of substrates 4a and 4b is formed with a distance of 1 μm between the substrates, and the pair of substrates 4a and 4b is converted to 4-dimethylamino-N—. A pair of substrates 4a and 4b are brought into contact with DAST methanol solution 5 (solution) prepared by adding 1 ml of methanol to 25 mg of methyl-4-stilbazolium tosylate (DAST, organic substance) and utilizing capillary action or the like. The DAST methanol solution 5 was filled in the gap.

  Next, after removing the container 3 containing methanol from the production container 1, a pair of substrates 4a and 4b filled with a DAST methanol solution 5 in the gap was placed in the production container 1 (FIG. 1-2). At this stage, since the inside of the production container 1 is saturated with methanol vapor, methanol does not evaporate from the DAST methanol solution 5 present in the gap between the pair of substrates 4a and 4b.

  Separately, the inside of the gas storage container 2 containing methanol is kept at a temperature of 15 ° C. in a thermostatic bath, the inside of the gas storage container 2 is saturated with methanol vapor, and nitrogen gas is then added to the methanol at a rate of 0 per minute. An additive gas consisting of methanol saturated vapor and nitrogen gas was produced.

  In addition, it is desirable to flow nitrogen gas into methanol. The contact area between nitrogen gas and methanol per hour increases, the amount of methanol vapor in the mixed gas becomes constant, and the mixing ratio of the mixed gas becomes stable. On the other hand, if nitrogen gas is not flowed into methanol, there is not enough time for methanol to reach a liquid / gas equilibrium state, methanol vapor decreases, and the ratio of methanol vapor in the mixed gas decreases. Because.

  Moreover, it is desirable that the tip of the tube through which nitrogen gas flows into methanol be porous like a glass filter. This is because the contact area between nitrogen gas and methanol per hour increases, and an additive gas composed of methanol saturated vapor and nitrogen gas can be efficiently produced.

  Then, the prepared additive gas was flowed from the gas storage container 2 into the preparation container 1 at a flow rate of 0.5 ml per minute by adjusting the introduction gas flow rate valve 8 (FIGS. 1-3). Here, since the saturation amount of methanol vapor at 15 ° C. is smaller than the saturation amount of methanol vapor at 20 ° C., the amount of methanol vapor in the production container 1 held at 20 ° C. gradually decreases. Methanol gradually evaporated from the DAST methanol solution 5 filled in the gap between the pair of substrates 4a and 4b, and the concentration of DAST in the DAST methanol solution increased, whereby the organic single crystal 6 began to precipitate.

  As a matter of course, a case where an additive gas containing a saturated vapor of methanol and nitrogen gas is caused to flow into the production container 1 is a pair of a case where only a normal nitrogen gas is caused to flow into the production container 1. The evaporation rate of methanol from the DAST methanol solution 5 filled in the gap between the substrates 4a and 4b can be reduced, and the evaporation amount of methanol can be controlled.

  In addition, crystal growth caused as a result of evaporation of methanol from the DAST methanol solution 5 filled in the gap between the pair of substrates 4a and 4b causes many crystals to precipitate in a short time when methanol is rapidly evaporated from the DAST methanol solution 5. Therefore, each crystal does not grow greatly, and there is a problem that it becomes a polycrystal state or a solvent is taken into the crystal and becomes a defect, but by slowing the evaporation rate, The number of crystals can be reduced and increased.

  168 hours (7 days later) after the additive gas began to flow into the production container 1, the solvent present in the gap between the pair of substrates 4a and 4b was completely extinguished. Thereafter, the gas introduced into the production container from the gas introduction port of the production container 1 was changed to only nitrogen gas and continued to flow for 5 hours to completely remove the methanol in the production container 1 (FIGS. 1-4).

  When the pair of substrates 4a and 4b were taken out and the crystals were confirmed, three organic single crystals 6 having a thickness of 1 μm and about 5.0 mm × about 5.0 mm could be obtained. In order to investigate the uniformity of the crystal, it was observed with a polarizing microscope, and it was confirmed that the entire crystal was uniformly extinguished and free from defects, and that a large and high-quality organic single crystal 6 was obtained. It was.

(Example 2)
First, after the preparation container 1 and the gas storage container 2 containing methanol were connected, the inside of both containers was kept at 20 ° C. for 2 hours in a thermostatic bath, and the inside of the preparation container 1 was saturated with methanol vapor ( Fig. 2-1). Here, 0.5 ml of nitrogen gas was allowed to flow into the methanol in the gas storage container 2 per minute.

  Separately, two circular quartz substrates having a diameter of 100 mm are prepared, a pair of substrates 4a and 4b is formed with a distance of 1 μm between the substrates, and 1 ml of methanol is added to the pair of substrates 4a and 4b per 25 mg of DAST. After making contact with the prepared DAST methanol solution 5 and using a capillary phenomenon or the like to fill the gap between the pair of substrates 4a and 4b with the DAST methanol solution 5, the pair of substrates 4a and 4b with the DAST methanol solution 5 filled in the gap 4b was installed in the production container 1 (FIG. 2-2). At this stage, since the inside of the production container 1 is saturated with methanol vapor, methanol does not evaporate from the DAST methanol solution 5 present in the gap between the pair of substrates 4a and 4b.

  Then, the inside of the gas storage container 2 is brought to 15 ° C. in a constant temperature bath, and an additive gas containing saturated methanol vapor and nitrogen gas is adjusted from the gas storage container 2 into the production container 1 every minute by adjusting the introduction gas flow valve 8. The flow was 0.5 ml (FIG. 2-3).

  168 hours (7 days later) after the additive gas began to flow into the production container, the solvent present in the gap between the pair of substrates 4a and 4b was completely extinguished. Thereafter, the gas introduced into the production container 1 from the introduction port of the production container 1 was changed to only nitrogen gas and kept flowing for 5 hours to completely remove the methanol in the production container 1 (FIG. 2-4).

  When the pair of substrates 4a and 4b were taken out and the crystals were confirmed, three organic single crystals 6 having a thickness of 1 μm and about 5.0 mm × about 5.0 mm could be obtained. Here, in order to examine the uniformity of the crystal, observation with a polarizing microscope was performed, and it was confirmed that the entire crystal was uniformly extinguished and free of defects, and a large-sized and high-quality organic single crystal 6 was obtained. I understood it.

Example 3
The same operation as in Example 2 was repeated, and the inside of the production container 1 (20 ° C.) was saturated with methanol vapor (FIG. 3A).

  Separately, two circular quartz substrates having a diameter of 100 mm are prepared, a PET film having a thickness of 12 μm is arranged between the two circular quartz substrates to form a spacer 7, and a pair of substrates 4 a and 4 b having a gap of 12 μm. Was prepared (FIG. 4).

  Next, the pair of substrates 4a and 4b is brought into contact with the DAST methanol solution 5 prepared by adding 1 ml of methanol per 30 mg of DAST, and the gap between the pair of substrates 4a and 4b is filled with the DAST methanol solution 5 using a capillary phenomenon or the like. After that, a pair of substrates 4a and 4b filled with the DAST methanol solution 5 in the gap was placed in the production container 1 (FIG. 3-2). At this stage, since the inside of the production container 1 is saturated with methanol vapor, methanol does not evaporate from the DAST methanol solution 5 present in the gap between the pair of substrates 4a and 4b.

  Then, the inside of the gas storage container 2 is brought to 17 ° C. in a thermostatic bath, and an additive gas containing saturated methanol vapor and nitrogen gas is adjusted from the gas storage container 2 into the production container 1 every minute by adjusting the introduction gas flow valve 8. The flow was 0.5 ml (FIG. 3-3).

  240 hours (10 days later) after the additive gas began to flow into the production container 1, the solvent present in the gap between the pair of substrates 4a and 4b was completely extinguished. Thereafter, the production container 1 is kept at 30 ° C., and the gas introduced into the production container 1 from the introduction port of the production container 1 is changed to only nitrogen gas and kept flowing for 5 hours to completely remove the methanol in the production container 1. (FIG. 3-4).

  When the pair of substrates 4a and 4b were taken out and the crystals were confirmed, three organic single crystals 6 having a thickness of 12 μm and about 3.0 mm × about 3.0 mm could be obtained. Here, in order to investigate the uniformity of the crystal, observation with a polarizing microscope was carried out. As a result, it was confirmed that the entire crystal was uniformly extinguished and free of defects, and a large and high-quality organic single crystal 6 was obtained. I found out.

(Comparative Example 1)
The same operation as in Example 2 was repeated except that the additive gas containing saturated methanol vapor and nitrogen gas was replaced with nitrogen gas only.

  Three hours after the nitrogen gas began to flow into the production vessel 1, the solvent present in the gap between the pair of substrates 4a and 4b disappeared completely.

  A large number of crystals of several μm to several tens of μm were deposited in the gap between the pair of substrates 4a and 4b. These crystals were found to have defects that may be due to cracks and solvent incorporation.

It is a figure which shows an example of the outline of the procedure in the preparation methods of the thin film organic single crystal of this invention. It is a figure which shows another example of the outline of the procedure in the preparation methods of the thin film organic single crystal of this invention. It is a figure which shows another example of the outline of the procedure in the preparation methods of the thin film organic single crystal of this invention. It is the schematic which shows an example of a pair of board | substrate which installed the spacer and formed the clearance gap. FIG. 4 is a diagram showing a structural formula of 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Preparation container 2 Gas storage container 3 Container 4a, 4b A pair of substrates 5 DAST methanol solution 6 Organic single crystal 7 Spacer 8 Introducing gas flow valve 9 Exhaust gas flow valve

Claims (7)

  A gap formed by a pair of substrates is filled with a solution obtained by dissolving an organic substance to be crystallized in a solvent, and then the rate of evaporation of the solvent from the pair of substrates filled with the solution is controlled. A method for producing a thin-film organic single crystal, comprising producing an organic single crystal.   Control of the rate of evaporation of the solvent is performed by installing a pair of substrates filled with the solution in a sealable production container and then from a gas storage container containing an additive gas containing a certain amount of vapor of the solvent. The method for producing a thin-film organic single crystal according to claim 1, wherein the additive gas is introduced into a production container.   The method for producing a thin-film organic single crystal according to claim 2, wherein the rate of evaporation of the solvent is controlled by controlling the inside of the production container and the inside of the gas storage container at different temperatures.   Control of the speed at which the solvent is evaporated is controlled by evaporating the solvent until the solvent is saturated, and after the inside of the preparation container is saturated with the solvent vapor, a pair of substrates filled with the solution can be sealed. 4. The method for producing a thin-film organic single crystal according to claim 2 or 3, wherein the thin-film organic single crystal is disposed inside.   The method for producing a thin-film organic single crystal according to claim 1, wherein the gap is formed by installing a spacer between the pair of substrates.   6. The method for producing a thin-film organic single crystal according to claim 1, wherein the organic substance is 4-dimethylamino-N-methyl-4-stilbazolium tosylate. . A gas introduction port for introducing gas, an introduction gas flow valve for adjusting the flow rate of gas introduced from the gas introduction port, a gas discharge port for discharging gas, and a flow rate of gas discharged from the gas discharge port are adjusted. A sealable production container having an exhaust gas flow valve, and a gas storage container connected to the gas inlet and storing an additive gas containing a certain amount of vapor of a solvent that dissolves an organic substance to be crystallized. An apparatus for producing a thin-film organic single crystal,
An apparatus for producing a thin-film organic single crystal, characterized in that the inside of the production container and the inside of the gas storage container can be controlled at different temperatures.

Images