JP2006035087A - Method and apparatus for forming organic material thin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form an organic material thin film having sufficient flatness on a flexible substrate such as a plastic. <P>SOLUTION: A method for forming the organic material thin film comprising a process of applying an organic material solution onto the flexible substrate 10, a process of incurvating the flexible substrate 10 so that an applied surface is the outside before the organic material solution solidifies and a process of flattening the incurvated flexible substrate 10, is provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for forming an organic material thin film. In particular, the present invention relates to an organic material thin film having sufficient flatness on a flexible substrate such as plastic, which is required when manufacturing an electronic device capable of deforming a substrate, such as a wearable PC or a flexible display. The present invention relates to a forming method and a forming apparatus.

  In recent years, the characteristics of organic electronic materials have made remarkable progress. For example, an organic EL display or an organic LED display has advantages in that each pixel individually emits light, so that a viewing angle is wide and a color filter is not necessary. Furthermore, since these displays do not require a backlight, they can be made thin and can be formed on a flexible substrate such as plastic. Yes. In addition, the use of an organic material for the circuit system for driving it is also being considered, and it is expected that an electronic device capable of deforming a substrate, such as a wearable PC or a flexible display, will be realized.

  An organic electronic material constituting such a display is formed as a thin film on a substrate. The film thickness of the organic electronic material is approximately in the range of several tens to several hundreds of nanometers, and vacuum deposition, solution coating (spin coating method, ink jet method) or the like is used as a thin film forming method. As the substrate, glass, silicon, and plastic are often used, and a metal electrode, an oxide (ITO, etc.) electrode, an insulating film, and the like are formed thereon as necessary. As a method for forming a metal electrode, an oxide (ITO) electrode, or an insulating film, sputtering, CVD, PVD, or the like is used in addition to vacuum deposition and solution coating (spin coating method, ink jet method).

As a method for forming a thin film on a flexible substrate, there is known a method (patent document 1) of reducing a stress remaining in a thin film by deforming the substrate during film formation when forming a diamond thin film by a vapor phase method. . In addition, when a metal or metal compound is formed on a plastic substrate by sputtering or the like, a method of forming a film in a state where the substrate is deformed in advance in order to reduce the compressive stress of the thin film is also disclosed (Patent Document 2). Are known. However, there is no example describing this as a specific method for forming an organic material thin film by application of a solution.
JP-A-6-280026 Japanese Patent Laid-Open No. 11-80928

  In the above, the merit of using an organic material as an electronic material is that a low-cost manufacturing method such as solution coating (spin coating method, ink jet method) can be used, and a plastic substrate can be used because the process temperature is low. There is, therefore, a flexible electrical device can be manufactured using it. However, the formation of the organic material thin film by solution coating has the following problems.

  That is, the thin film formed on the flexible substrate is distorted as the substrate is deformed. In particular, when an organic electronic material is formed by solution application, the film contracts as the solvent evaporates, and tensile strain occurs in the thin film. In particular, when the solvent is evaporated by heating the substrate, thermal strain due to a difference in thermal expansion coefficient between the substrate and the inorganic material layer laminated on the substrate also occurs. These strains may change the electrical characteristics of the organic material, resulting in unstable device characteristics. In particular, when the strain is severe on the pull side, the thin film may be peeled off or broken, and countermeasures have been required.

  An object of the present invention is to reduce tensile strain generated in a thin film when an organic electronic material thin film is formed by applying an organic material solution to a flexible substrate in view of the above points, thereby reducing the element characteristics. Is to secure.

The present invention has been made to achieve the above object. That is, according to one aspect of the present invention, there is provided a method for forming an organic material thin film, the step of applying an organic material solution on a flexible substrate, and the flexible material before the organic material solution is solidified. And a step of bending the flexible substrate so that the application surface is on the outside, and a step of flattening the curved flexible substrate. Here, the step of bending can be performed such that the thickness D of the flexible substrate and the radius of curvature R when bending are in a range of 1 × 10 ⁻² > D / 2R> 3 × 10 ^−3. .

  It is preferable that the method further includes a step of heating the applied organic material solution after the applying step and before the bending step.

  The method further includes the step of monitoring the surface temperature of the flexible substrate after the heating step and before the bending step, wherein the surface temperature is equal to or higher than the glass transition temperature of the organic material, or the organic material It is preferable to control the heating process so that the solution does not solidify.

  According to still another aspect of the present invention, there is provided an organic material thin film forming apparatus comprising: a flexible substrate supplying means; and an applying means for applying an organic material solution to the flexible substrate. Heating means for heating the organic material solution applied to the flexible substrate, means for monitoring the surface temperature of the flexible substrate, and the flexible substrate before the organic material solution is solidified. And a bending means for bending the coating surface so as to be on the outer side.

  ADVANTAGE OF THE INVENTION According to this invention, tensile strain is reduced, the organic material thin film which is flat and does not peel or crack, and the formation method and forming apparatus of such an organic material thin film are provided. And in such an organic material thin film, it becomes possible to stabilize the element characteristic. Furthermore, a low-cost and high-performance electronic material can be obtained by forming an organic material thin film having sufficient characteristics by solution application.

  Below, the formation method and formation apparatus of the organic material thin film which concern on this invention are demonstrated in detail with reference to drawings. The following description does not limit the invention. In the following description, the same reference numerals refer to the same members.

  First, FIG. 1 conceptually shows an embodiment of an organic material thin film forming apparatus according to the present invention. This forming apparatus is configured based on a so-called roll-to-roll method. The roll-to-roll method is a substrate transport method with the highest mass productivity when the substrate is a flexible substrate such as a plastic substrate. In the forming apparatus of FIG. 1, the flexible substrate 10 is continuously supplied from the feed roll 1, and is taken up by the take-up roll 4 through various processes. The feed roll 1 and the take-up roll 4 can each be driven by a motor. The flexible substrate 10 can be conveyed from the feed roll 1 to the take-up roll 4 via several guide rolls (not shown). During this time, the flexible substrate 10 is appropriately tensioned by several rollers. To suppress wrinkling and sagging. The supply speed of the flexible substrate 10, that is, the moving speed of the flexible substrate 10 can be set to 0.1 mm / sec to 1000 mm / sec. The moving speed depends on the type of solvent and the drying conditions, but if it is 0.1 mm / sec or less, the applied solution may flow due to gravity before drying, and the film thickness may become non-uniform. If it is 1000 mm / sec or more, the drying time is short and the vibration of the sheet becomes large, which may make stable coating processing difficult.

  Furthermore, the organic material thin film forming apparatus according to the present embodiment is based on such a roll-to-roll method, and includes, as main components, a feed roll 1, a coating roll 2, a coating head 11, , Heater 12, infrared thermometer 17, control device 18, drying roll 3, and take-up roll 4. The feed roll 1 is a supply unit for the flexible substrate 10. The coating roll 2 is a means for stabilizing the substrate position in coating with the coating head 11. The coating head 11 is a coating unit that applies an organic material solution to the flexible substrate. The heater 12 is a heating unit that heats the organic material solution applied to the flexible substrate 10. The infrared thermometer 17 is a means for monitoring the surface temperature of the flexible substrate 10. The control device 18 controls the heater according to the monitoring result by the infrared thermometer 17. The drying roll 3 is a bending unit that applies a predetermined compressive strain to the flexible substrate 10. The winding roll 4 is a means for flattening and winding up the flexible substrate 10 that has passed through the drying roll 3.

Next, an embodiment of a method for forming an organic material thin film using the forming apparatus according to the embodiment of FIG. 1 will be described. The method for forming an organic material thin film according to the present embodiment includes the following steps.
(1) Step of applying organic material solution onto flexible substrate (2) Step of heating organic material solution (3) Step of monitoring temperature of organic material solution application surface (4) Bending flexible substrate Step (5) Step of Flattening Flexible Substrate These steps (1) to (5) will be further described.

(1) Step of applying organic material solution on flexible substrate In the step of applying organic material solution on flexible substrate, organic material is used as a solvent on flexible substrate 10 supplied from feed roll 1. A solution obtained by dissolving is applied.

  Examples of the flexible substrate 10 include polyimide, polyetherimide, polysulfone, polyethersulfone, polyphenylene sulfide, rose-based aramid, polyetherkent, polyester, polycarbonate, polyimide, polyethersulfone, amorphous polyolefin, epoxy resin or A polymer plastic film such as a fluororesin can be used, but is not limited thereto. Among them, polyester or polycarbonate is preferable in terms of strength, and polyester such as polyethylene terephthalate is particularly preferable. The thickness of the flexible substrate is preferably 0.05 mm to 2 mm, and more preferably 0.1 mm to 1 mm. This is because the mechanical strength is not obtained when the thickness is 0.05 mm or less, and the distortion of the substrate surface and the thin film during bending may be excessive when the thickness is 2 mm or more.

  In addition, the flexible substrate 10 includes an electrode made of an aluminum electrode, an ITO electrode, a carbon electrode, or other materials in advance before applying the organic material solution of the present invention, but is not limited thereto, an inorganic material thin film May be formed. Moreover, various coating films for improving the smoothness and moisture resistance of the flexible substrate 10 may be formed. Such inorganic material thin films, types of coating films, and formation methods are known to those skilled in the art.

  The organic material solution constituting the organic material thin film can be prepared by dissolving or dispersing the organic material in an appropriate solvent. Suitable organic materials include condensed rings such as pentacene, anthracene, and tetracene with high carrier mobility, copper-phthalocyanine, aluminum quinolinol complex (tris-8-hydoroxyqunoline aluminum), and thiophene polymers. Without being limited thereto, a wide range of organic materials can be applied.

  The solvent that dissolves the organic material can be appropriately selected depending on the type of the organic material. For example, THF (tetrahydrofuran) and DCM (dichloromethane) are preferable because they can dissolve many organic materials. In addition, acetonitrile, benzene, butanol, cyclohexane, dichloroethane, ethanol, ethyl acetate, and the like can be used, but are not limited thereto.

  The organic material solution can be applied to the flexible substrate 10 by a known method such as blade coating or inkjet. In addition, screen printing, casting, dipping, spin coating and the like can be mentioned, but the method is not limited to these.

  The coating thickness varies depending on the type of organic material, the coating conditions, the purpose of use, etc., but the thickness at the time of coating can usually be about 10 nm to 1000 nm, and it should be 50 nm to 200 nm. preferable. This is because an electric withstand voltage cannot be obtained at 10 nm or less, and a sufficient current density cannot be obtained at 1000 nm or more.

  Application can be performed by the application head 11. Such an application head 11 may be located near the application roll 2 and apply on the application roll 2. Alternatively, the application head 11 can be positioned between the feed roll 1 and the application roll 2 as indicated by phantom lines, and the flexible substrate 10 can be applied in a flat state.

  In the coating process, in addition to applying the organic material solution as described above, a thin film is formed by the above-described appropriate method using the target low molecular precursor or the target polymer precursor, and then heat treatment is performed. The method of converting into the target organic-semiconductor layer by etc. is also mentioned. In that case, an appropriate condition can be given to the reaction of the precursor between the coating step and the heating step to be performed next.

(2) Step of heating organic material solution After the application step, a step of heating the organic material solution applied onto the flexible substrate 10 is performed. This is because the solvent is efficiently removed from the organic material solution so that the organic material solution is in a state suitable for the subsequent bending step. At this time, the heating temperature is controlled according to the surface temperature of the flexible substrate measured in the subsequent monitoring step. In the present invention, the surface temperature of the flexible substrate is considered to be substantially the same as the temperature of the organic material solution applied on the flexible substrate or the organic material thin film formed by solidification thereof. In order to monitor the state of the organic material solution applied on the flexible substrate or the organic material thin film formed by solidifying the organic material solution, the surface temperature of the flexible substrate can be measured. For example, the flexible substrate can be heated so that the surface temperature of the flexible substrate is about 10 to 20 ° C. higher than the glass transition temperature of the organic material. In addition, in a material in which it is difficult to define the solidification conditions at the glass transition temperature, the material can be heated to a temperature at which crystals do not precipitate.

  The heating can be performed by heating the organic material solution application surface of the flexible substrate 10 using a heater 12, for example, a resistance heater 12 such as an infrared lamp or an aluminum cast heater. The heater 12 can be arranged in a plane parallel to the flexible substrate 10. Further, in the above apparatus, the heating time can be adjusted by the feeding speed of the flexible substrate 10 and the length of the heater along the film moving direction. It can be determined to achieve the surface temperature.

(3) Step of monitoring the temperature of the organic material solution application surface Next to the heating step, a step of monitoring the surface temperature of the flexible substrate 10 is performed. This is because the coating solution on the flexible substrate 10 is subjected to a subsequent bending process in an appropriate state before the organic material solution is solidified. Here, it is preferable to control the surface temperature of the flexible substrate 10 to be monitored to be higher than the glass transition temperature. This is because when the organic material is an amorphous material and the solvent is removed by heating and evaporation, whether or not the solvent is solidified can be determined by whether or not the temperature is lower than the glass transition point. Temperature monitoring can be performed using an infrared thermometer 17. Moreover, it feeds back to the control apparatus 18 based on the monitoring result, the heater 12 is power-controlled, and the surface temperature of a flexible substrate is controlled by radiation heating.

  In addition, when it is difficult to define the solidification conditions at the glass transition point because the organic material solution forms a crystalline film at room temperature, the state is confirmed by visual and probe contact, The temperature condition can be set so that it has not started.

(4) The step of bending the flexible substrate In the subsequent step of bending the flexible substrate 10, the flexible substrate 10 is bent so that the application surface is on the outside. In the present invention, “curving” refers to bending a sheet-like flexible substrate in a certain direction so as not to cause an inflection point. This is to reduce the tensile strain by bringing the total strain closer to the compression side when a tensile strain accompanying evaporation of the solvent during coating or a strain accompanying deformation of the flexible substrate 10 occurs.

Specifically, the flexible substrate on which the organic material solution is applied so that the thickness D of the flexible substrate and the radius of curvature R to be curved satisfy 1 × 10 ⁻² > D / 2R> 3 × 10 ^−3. Can be curved. When D / 2R is smaller than 3 × 10 ^−3, the electrical characteristics of the organic material change due to tensile strain accompanying the evaporation of the solvent during coating, and as a result, the device characteristics become unstable. On the other hand, when D / 2R is larger than 1 × 10 ⁻² , the compressive strain remaining in the thin film becomes excessive, the substrate deforms into a convex shape, and the adhesion between the thin film and the substrate decreases. Strictly speaking, the thickness of the organic thin film layer affects the appropriate value for applying the compressive strain, but the thickness of the organic thin film layer is sufficiently smaller than the substrate thickness, and adhesion is good. In other words, since the organic thin film layer can be considered as a part of the substrate, in the present invention, it is defined only by D and R.

  In order to bend in this way, it is effective to transport the flexible substrate 10 through the drying roll 3 having an appropriate curvature radius determined as described above. In addition, the flexible substrate 10 can be bent so as to generate a predetermined compressive strain by a method such as fixing the flexible substrate 10 on an appropriate mold or the like by batch processing. It is not limited to a specific method.

(5) Step of flattening the flexible substrate After the step of bending the flexible substrate 10 bent under the conditions as described above, the organic material solution is solidified to become an organic material thin film, and then flattened. Turn into. This is because compressive strain is applied to the organic material thin film by planarization. This step is carried out by conveying the flexible substrate 10 that has been bent once by being conveyed through the drying roll 3 as described above, in a flat state before being wound around the take-up roll 4 or the like. Can do. And optionally, immediately after the drying roll 3, it is possible to monitor the surface temperature of the flexible substrate 10 to be lower than the glass transition point or the crystal precipitation temperature.
Note that the substrate is not limited to flattening after solidification, and the substrate can be flattened in a semisolid state before reaching the solidification temperature, and even when flattened in a semisolid state, tensile strain is suppressed. Effect can be obtained.

The organic material thin film formed on the flexible substrate manufactured through the steps (1) to (5) does not cause peeling or cracks, and has preferable rectification characteristics, particularly Preferably, the current ratio between + 5V and −5V has a good rectification ratio of 10 ⁵ .

In the above method, in a state where the organic material is applied as a solution, the material is a liquid, so that no distortion occurs. The material is gradually solidified by evaporation of the solvent. In the present invention, the substrate is curved into a predetermined shape before the material is solidified, and then flattened after solidification, thereby applying compressive strain to the organic material thin film. Is. In general, compressive strain has a greater tolerance to breakage when loaded on a material than tensile strain. Therefore, setting the strain to the compression side is effective in terms of ensuring the soundness of the organic material film. When the coated substrate surface is restored to a flat shape by the forming method of the present invention, the organic material thin film is preliminarily loaded with a compressive strain of ³ × 10 ⁻³ or more. When the distortion due to the deformation occurs, the total distortion can be brought closer to the compression side, and the tensile distortion can be reduced.

  In the method for forming an organic material thin film according to this embodiment, a heating process, a monitoring process, and a control process are included, but the substrate is bent into a predetermined shape before the material is solidified, and is flattened before or after solidification. It is not essential to include a heating step, a monitoring step, and a control step as long as a predetermined compressive strain can be applied.

  Further, in the method for forming an organic material thin film according to the present embodiment, a process for applying a single layer of an organic material has been exemplified. However, when a plurality of layers are stacked, a plurality of processes (1) to (5) are performed. Can be repeated. FIG. 2 shows an organic material thin film forming apparatus used when a plurality of layers are stacked. In the forming apparatus according to this embodiment, three coating units 21 are included between the feed roll 1 and the take-up roll 4. The application unit 21 can include the application head 11, the application roll 2, the heater 12, the infrared thermometer 17, the control device 18, and the drying roll 3 of FIG. 1. However, the present invention is not limited to an apparatus including three coating units 21 as illustrated.

Hereinafter, the present invention will be described in detail based on examples.
Using a polyethylene terephthalate sheet (thickness 300 μm) whose surface was previously coated with an aluminum electrode film (thickness 60 nm) as the flexible substrate 10, a thin film was formed using an apparatus having the configuration shown in FIG. 1.

  A blade was installed as the coating head 11 in the coating roll 2. Thereafter, the flexible substrate 10 was heated by the heater 12 in order to evaporate and remove (dry) the solvent of the applied solution. The heater 12 was an infrared lamp and was arranged in a plane parallel to the flexible substrate 10. The temperature of the flexible substrate 10 immediately before the drying roll 3 is monitored by the infrared thermometer 17 and fed back to the control device 18 based on the temperature. The heater 12 is power-controlled, and the flexible substrate 10 is heated by radiation heating. Controlled.

As the organic material, a biskinomethane compound having the following chemical structure (chemical formula I) was used, and this was dissolved in THF (tetrahydrofuran) at a concentration of 3% by mass to obtain a coating solution.

The distance between the blade and the coated substrate was controlled to 0.2 mm, and the film substrate was moved at a speed of 30 mm / sec. The heating temperature in the heater 12 was set at a maximum of 130 ° C., and the temperature distribution was adjusted so that the surface temperature of the flexible substrate immediately before the drying roll was 118 ° C. or higher of the organic material. The radius of the drying roll 3 was 30 mm. The surface temperature after passing through the drying roll is about 72 ° C., and the organic material thin film is solidified. As a result, the organic material thin film has a compressive strain of D / 2R = 0.3 / 2/30 = 5 × 10 ^−3. Granted. The organic material thin film on the substrate reaching the winding roll 4 was flat and had no damage. Further, when a part thereof was cut out to 50 × 50 mm ² and placed on a flat plate, the planar shape was generally maintained. Thereafter, an aluminum electrode was deposited on the organic film, and electrical characteristics were measured between the upper and lower electrodes. The results are shown in FIG. Predetermined rectification characteristics were obtained.

The organic material to be applied was a dicyano compound having the following chemical structure (Chemical Formula II), dissolved in methanol at a concentration of 3% by mass, and the temperature immediately before the drying roll 3 was 120 ° C. Similarly to Example 2.

Since this material forms a crystalline film at room temperature, it is difficult to define the solidification conditions by the glass transition point. However, the state was confirmed by visual observation and probe contact, and the above temperature conditions were set. As a result, as in Example 1, the organic material thin film on the substrate reaching the take-up roll 4 was flat and had no damage. Further, when a part thereof was cut out to 50 × 50 mm ² and placed on a flat plate, the planar shape was generally maintained. Thereafter, an aluminum electrode was deposited on the organic film, and electrical characteristics were measured between the upper and lower electrodes. The results are shown in FIG. Predetermined bistable characteristics were obtained.

Example 3 was made in the same manner as Example 1 except that the thickness of the polyethylene terephthalate sheet of the flexible substrate 10 was 100 μm and the radius of the drying roll 3 was 15 mm. The substrate temperature after passing through the drying roll 3 is about 76 ° C., and the organic material thin film is solidified. As a result, the organic material thin film has D / 2R = 0.1 / 2/15 = 3.3 × 10 ^−3. The compression strain of was given. The organic material thin film on the substrate reaching the winding roll 4 was flat and had no damage. Further, when a part thereof was cut out to 50 × 50 mm ² and placed on a flat plate, the planar shape was generally maintained. Thereafter, an aluminum electrode was deposited on the organic film, and electrical characteristics were measured between the upper and lower electrodes. As a result, predetermined rectification characteristics (not shown) were obtained.

Example 3 was made in the same manner as Example 1 except that the radius of the drying roll was 15 mm. The substrate temperature after passing through the drying roll is about 76 ° C., and the organic material thin film is solidified. As a result, the organic material thin film has a compression of D / 2R = 0.3 / 2/15 = 1.0 × 10 ⁻² . Strain was applied. The organic material thin film on the substrate that reached the winding roll was flat and had no damage. Further, when a part thereof was cut out to 50 × 50 mm ² and placed on a flat plate, although the coating surface was slightly convex, a substantially planar shape was maintained. Thereafter, an aluminum electrode was deposited on the organic film, and electrical characteristics were measured between the upper and lower electrodes. As a result, predetermined rectification characteristics (not shown) were obtained.
[Comparative Example 1]

Comparative Example 1 was obtained in the same manner as in Example 1 except that the drying roll 3 was not used and the film was heated and dried with the heater 12 and then directly wound with the winding roll 4. Some cracks were observed in the organic material thin film on the substrate that reached the winding roll 4. Further, when a part thereof was cut out to 50 × 50 mm ² and placed on a flat plate, the coated surface became concave and the planar shape was not maintained, and when it was intentionally made flat, peeling was observed on some organic material thin films. With this sample, the electrical characteristics could not be obtained.
[Comparative Example 2]

Comparative Example 2 was made in the same manner as Example 1 except that a roll having a radius of 60 mm was used as the drying roll 3. D / 2R corresponds to 2.5 × 10 ⁻³ . The organic material thin film on the substrate reaching the winding roll 4 was flat and had no damage. Further, when a part thereof was cut out to 50 × 50 mm ² and placed on a flat plate, the coated surface became concave, but the planar shape was maintained. Thereafter, an aluminum electrode was deposited on the organic film, and electrical characteristics were measured between the upper and lower electrodes. The results are shown in FIG. Compared with Example 1, the current density was reduced by about two orders of magnitude.
[Comparative Example 3]

Comparative Example 3 was made in the same manner as Example 1 except that a roll having a radius of 12 mm was used as the drying roll 3. D / 2R corresponds to 1.2 × 10 ⁻² . The organic material thin film on the substrate reaching the winding roll 4 was flat and had no damage. Further, when a part thereof was cut out to 50 × 50 mm ² and placed on a flat plate, the coated surface became convex and the planar shape could not be maintained. In addition, a slight decrease in adhesion was observed. Thereafter, an aluminum electrode was deposited on the organic film, and electrical characteristics were measured between the upper and lower electrodes. As a result, predetermined rectification characteristics (not shown) were obtained.

  As an application example of the present invention, an electronic device such as an organic EL display or an organic LED display can be configured.

It is explanatory drawing which shows the outline | summary of the organic material thin film formation method concerning this invention. In the organic material thin film formation method which concerns on this invention, it is explanatory drawing which shows the outline | summary in the case of forming a some layer. 2 is a graph showing electrical characteristics of an organic material thin film obtained in Example 1. FIG. 4 is a graph showing electrical characteristics of an organic material thin film obtained in Example 2. 6 is a graph showing electrical characteristics of an organic material thin film obtained in Comparative Example 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Feeding roll 2 Application | coating roll 3 Drying roll 4 Take-up roll 10 Flexible substrate 11 Application | coating head 12 Heater 17 Infrared thermometer 18 Control apparatus 21 Application | coating unit

Claims (5)

Applying an organic material solution onto the flexible substrate;
Before the organic material solution solidifies, the step of bending the flexible substrate so that the coating surface is on the outside;
Flattening the curved flexible substrate, and forming an organic material thin film. The bending step is performed such that the thickness D of the flexible substrate and the radius of curvature R when the bending are satisfied satisfy 1 × 10 ⁻² > D / 2R> 3 × 10 ^−3. The method described. The method according to claim 1, further comprising a step of heating the applied organic material solution after the applying step and before the bending step. The method further includes the step of monitoring the surface temperature of the flexible substrate after the heating step and before the bending step, wherein the surface temperature is equal to or higher than the glass transition temperature of the organic material, or the organic material The method of Claim 3 which controls a heating process so that it may become the temperature which does not solidify a solution. Flexible substrate supply means;
Application means for applying an organic material solution to the flexible substrate;
Heating means for heating the organic material solution applied to the flexible substrate;
Means for monitoring the surface temperature of the flexible substrate;
An apparatus for forming an organic material thin film, comprising: bending means for bending the flexible substrate so that an application surface is outside before the organic material solution is solidified.

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