JP4956709B2 - Method for producing organic semiconductor film - Google Patents

Description

  The present invention relates to a method for producing an organic semiconductor film made of an organic semiconductor compound.

In recent years, research on organic devices including organic semiconductor films made of organic semiconductor compounds has been widely conducted for the purpose of reducing the weight and flexibility of electronic devices.
As a method for producing an organic semiconductor film, for example, a vapor phase growth method in which an organic semiconductor film is formed on a substrate surface by vacuum deposition or sputtering, a liquid phase film formation method in which an organic semiconductor film is formed by coating, casting, or the like is known. ing. In addition, a vapor transport growth method has been proposed in which a raw material of an organic semiconductor compound is thermally decomposed in a decomposition container, and the decomposition product is vapor transported to a substrate in a deposition container to grow a film on the substrate surface. (See Non-Patent Document 1).
By the way, the organic semiconductor film is required to have high orientation because of improved electrical characteristics and optical characteristics. As a method for improving the orientation of the organic semiconductor film, for example, a method of treating the substrate surface in a vapor phase growth method or selecting an appropriate temperature is known, and a monomolecular film method is used in a liquid phase film formation method Self-alignment methods such as are known.
Bruce J. Humphrey, “Journal of American Institute for Conservation”, USA, 1986, Vol. 25, No. 1, p. 15-29

However, none of the conventionally known methods for producing an organic semiconductor film is a simple method and is not suitable for practical use, and the orientation of the obtained organic semiconductor film is insufficient.
This invention is made | formed in view of the said situation, and it aims at providing the manufacturing method of the organic-semiconductor film which can manufacture the organic-semiconductor film with sufficiently high orientation easily.

The present invention includes the following configurations.
[1] Tetracene, pentacene, quaterphenyl, quinquephenyl, sexual phenyl, thiophene-phenylene co-oligomer, compound represented by chemical formula (6) described later, compound represented by chemical formula (7), chemical formula (8) An organic semiconductor film manufacturing method for forming an organic semiconductor film on a surface of a substrate by vapor phase growth using an organic semiconductor compound selected from the compounds represented by
The organic semiconductor compound is placed on a support base, after which the organic semiconductor compound and the surface of the substrate placed the substrate so as to face with a gap of 10μm~1cm is formed between the organic semiconductor compound, pressure 10 ^- An organic semiconductor film manufacturing method comprising forming an organic semiconductor film on a surface of a substrate by heating and sublimating an organic semiconductor compound in an atmosphere of ² Pa to 10 ⁶ Pa.
[2] The method for producing an organic semiconductor film according to [1], wherein when the organic semiconductor compound is heated, the substrate and a part of the organic semiconductor compound are brought into contact with each other.
[3] The method for producing an organic semiconductor film according to [2], wherein the heating temperature of the organic semiconductor compound is not higher than the melting point of the organic semiconductor compound.
[4] The method for producing an organic semiconductor film according to [1], wherein a gap is provided between the substrate and all of the organic semiconductor compound.
[5] The method for producing an organic semiconductor film according to any one of [1] to [4], wherein an atmosphere when the organic semiconductor compound is heated is a nitrogen atmosphere.

  According to the method for producing an organic semiconductor film of the present invention, an organic semiconductor film having sufficiently high orientation can be easily produced.

(First embodiment)
A first embodiment of the method for producing an organic semiconductor film of the present invention will be described.
The method for producing an organic semiconductor film according to the present embodiment is a method for forming an organic semiconductor film on the surface of a substrate by vapor phase growth using an organic semiconductor compound as a raw material. In this method, the organic semiconductor compound is heated in a contact state.
This will be specifically described below.

In the method for producing an organic semiconductor film of the present embodiment, first, as shown in FIG. 1, a powdery organic semiconductor compound A is placed on a support base 12 disposed on a heater 11. A substrate 13 is placed on A. Here, since the organic semiconductor compound A is in powder form, as shown in FIG. 2, a part of the organic semiconductor compound A and the substrate 13 are in contact with each other, but there is a gap N between the organic semiconductor compound A and the substrate 13. Is also formed.
Next, the heater 11 is heated, and the organic semiconductor compound A is heated via the support 12 to sublimate (vaporize) the organic semiconductor compound A. Then, an organic semiconductor film made of an organic semiconductor compound is formed on the lower surface of the substrate 13.

In this manufacturing method, the atmospheric pressure when heating the organic semiconductor compound A is set to 10 ⁻² Pa to 10 ⁶ Pa. When the pressure of the atmosphere is less than 10 ⁻² Pa, the orientation of the obtained organic semiconductor film is lowered. In addition, by setting the atmospheric pressure to 10 ⁶ Pa or less, it is not necessary to use a container with high pressure resistance, and the apparatus for manufacturing the organic semiconductor film can be configured simply.
In this manufacturing method, the orientation of the obtained organic semiconductor film can be secured even when the atmospheric pressure is set to atmospheric pressure or higher.

  The atmosphere at the time of heating may be, for example, an inert gas atmosphere such as nitrogen or argon, or may be an atmosphere containing oxygen such as air if the organic semiconductor compound is not denatured. Among these, a nitrogen atmosphere is preferable in that a high-performance organic semiconductor film can be manufactured.

  The heating temperature of the organic semiconductor compound A is preferably not higher than the melting point of the organic semiconductor compound A, and more preferably 1 to 100 ° C. lower than the melting point of the organic semiconductor compound A. However, the heating temperature is not lower than the lowest temperature (specifically, about 40 ° C.) that can be controlled in heating.

  The temperature of the substrate 13 is preferably lower than the temperature of the organic semiconductor compound A because an organic semiconductor film can be easily formed. In order to make the temperature of the substrate 13 lower than the temperature of the organic semiconductor compound A, the substrate 13 may be cooled.

  The organic semiconductor compound A used in this production method is usually a π-conjugated compound, for example, tetracene (chemical formula (1)), pentacene (chemical formula (2)), quaterphenyl (chemical formula (3)). , Quinquephenyl (Chemical Formula (4)), Sexiphenyl (Chemical Formula (5)), and the like.

Moreover, as organic-semiconductor compound A, a thiophene-phenylene co-oligomer is mentioned. Here, the thiophene-phenylene co-oligomer is a compound in which a thiophene ring and a phenylene (benzene) ring are bonded one-dimensionally.
Specific examples of the thiophene-phenylene co-oligomer include those represented by the following chemical formulas (6) to (23).

Among the organic semiconductor compounds, a thiophene-phenylene co-oligomer is preferable because an organic semiconductor film with higher orientation can be produced.
In addition, Table 1 shows melting points of the chemical formulas (1) to (23).

  As the substrate 13, for example, an inorganic semiconductor substrate such as a silicon substrate, a glass substrate, a polyimide substrate, or the like can be used. Among these, the polyimide substrate has a thermal expansion coefficient close to that of the organic semiconductor compound, and contracts substantially the same as the organic semiconductor film during cooling, so that cracks due to a difference in contraction from the substrate 13 are unlikely to occur. Therefore, an organic semiconductor film having a larger domain size is finally obtained.

  In the manufacturing method according to the first embodiment described above, the organic semiconductor compound sublimated by heating adheres to the surface of the substrate 13 through the gap N between the organic semiconductor compound A and the substrate 13. Therefore, an organic semiconductor film made of an organic semiconductor compound can be formed on the surface of the substrate 13 by vapor phase growth. In this manufacturing method, it is not necessary to use a special atmosphere such as a high vacuum, and a complicated operation is not required, so that an organic semiconductor film can be easily manufactured. Moreover, as a result of investigations by the present inventors, it was found that the organic semiconductor film obtained by the manufacturing method of this embodiment example has a sufficiently high orientation.

(Second Embodiment)
A second embodiment of the method for producing an organic semiconductor film of the present invention will be described.
The method for producing an organic semiconductor film according to the present embodiment is a method of forming an organic semiconductor film on a substrate surface by vapor phase growth using an organic semiconductor compound as a raw material, without contacting the organic semiconductor compound and the substrate. In this method, the organic semiconductor compound is heated in a state having an interval.
This will be specifically described below.

In the method for producing an organic semiconductor film of this embodiment, first, as shown in FIG. 3, a film-like organic semiconductor compound B is placed on a support base 12 disposed on the heater 11, and the film on the support base 12 is placed. Two spacers 14a and 14b are placed on both ends of the organic semiconductor compound B, and the substrate 13 is placed on the two spacers 14a and 14b. Here, examples of the film-like organic semiconductor compound B include those obtained by once melting and cooling a powdery organic semiconductor compound.
Next, the heater 11 is heated, and the film-like organic semiconductor compound B is heated via the support 12 to sublimate (vaporize) the organic semiconductor compound. Then, an organic semiconductor film made of an organic semiconductor compound is formed on the lower surface of the substrate 13.

In this manufacturing method, the atmospheric pressure when heating the film-like organic semiconductor compound B is set to 10 ⁻² Pa to 10 ⁶ Pa for the same reason as in the first embodiment.
As the organic semiconductor compound and the substrate 13, the same materials as those in the first embodiment can be used.

  The heating temperature of the film-like organic semiconductor compound B may be equal to or lower than the melting point of the organic semiconductor compound or may exceed the melting point. However, in order to ensure a sufficient amount of sublimation of the organic semiconductor compound, it is preferable that the heating temperature is not higher than the melting point and not lower than (melting point−100 ° C.).

In this embodiment, the gap N is provided without contacting the substrate 13 and the film-like organic semiconductor compound B by the two spacers 14a and 14b on both ends of the film-like organic semiconductor compound B. The distance between the substrate 13 and the film-like organic semiconductor compound B is preferably 10 μm to 1 cm. If the distance between the substrate 13 and the film-like organic semiconductor compound B is 10 μm or more, the film thickness can be easily made uniform, and if it is 1 cm or less, the crystal size can be increased.
Examples of the material of the spacer include glass, metal, and ceramics.

In the manufacturing method of the second embodiment described above, the organic semiconductor compound sublimated by heating adheres to the surface of the substrate 13 through the gap N between the film-like organic semiconductor compound B and the substrate 13. Therefore, also in this embodiment, an organic semiconductor film made of an organic semiconductor compound can be easily formed on the surface of the substrate 13 by vapor phase growth. Moreover, as a result of investigations by the present inventors, it has been found that the organic semiconductor film obtained by the production method of this embodiment example has sufficiently high orientation.
In the second embodiment described above, since the organic semiconductor compound as a raw material is formed into a film shape, the organic semiconductor compound can be uniformly sublimated, and the thickness of the obtained organic semiconductor film can be easily made uniform. .

The present invention is not limited to the above-described embodiment example. For example, although the organic semiconductor compound in the first embodiment described above is in a powder form, it may be a film-shaped organic semiconductor compound C having irregularities on the surface as shown in FIG. Even in this case, a part of the organic semiconductor compound C comes into contact with the substrate 13 to form the gap N.
The form of the organic semiconductor compound in the second embodiment described above is a film, but may be a powder.
In the second embodiment, a gap is provided between the organic semiconductor compound and the substrate using a spacer. However, a gap is provided between the organic semiconductor compound and the substrate using a jig for fixing the substrate. It may be provided.

Example 1
Example 1 is an example corresponding to the first embodiment, and a cover glass of 18 mm × 18 mm is used as the support base 12, and the compound (5, 5) represented by the above chemical formula (22) is used as the organic semiconductor compound A. ″ ″ -Diphenyl-2,2 ′: 5 ′, 2 ″: 5 ″, 2 ′ ″: 5 ′ ″, 2 ″ ″-kinquethiophene, hereinafter referred to as P5T). A powder was used, and a silicon substrate with an oxide film of 15 mm × 15 mm was used as the substrate 13.
In the manufacturing method of this example, first, powdery P5T was placed on the support base 12 disposed on the heater 11, and the substrate 13 was placed on P5T. Next, the heater 11 sublimates the P5T on the support base 12 under a nitrogen atmosphere at atmospheric pressure by heating at a heater temperature of 290 ° C. for 4 hours to form a surface of the silicon substrate with an oxide film located above the powdery P5T. Then, a P5T crystal film, which is an organic semiconductor film, was formed.

5 and 6 show microscopic images of the P5T crystal film obtained by the manufacturing method of Example 1, and FIGS. 6 is an image obtained by rotating the microscope image of FIG. 5 by 45 degrees, and the polarization microscope image of FIG. 8 is an image obtained by rotating the polarization microscope image of FIG. 7 by 45 degrees.
From these images, it can be confirmed that the film is oriented over a range of several tens of μm square. Further, the white portion surrounded by a line in the polarization microscope image of FIG. 7 was dark in the polarization microscope image of FIG. 8 after being rotated by 45 degrees. Therefore, the obtained crystal film has high polarization and high orientation.

(Example 2)
Example 2 is an example corresponding to the second embodiment, and a cover glass of 18 mm × 18 mm is used as the support 12, and the compound (5, 5) represented by the above chemical formula (23) is used as the organic semiconductor compound A. '''''-Diphenyl-2,2': 5 ', 2 ": 5", 2''': 5 ''',2'''':5'''',2''''' A film of Seccithiophene (hereinafter referred to as P6T) was used, and a silicon substrate with an oxide film of 2.9 mm × 20 mm was used as the substrate 13.
The P6T film was produced as follows. First, a 9 mm × 23 mm silicon substrate was placed on the heater, 5.03 mg of P6T powder was placed thereon, and a cover glass of 18 mm × 18 mm was placed on the P6T powder. Next, the P6T powder was melted by heating to a melting point of 392 ° C., and then cooled to room temperature to form a film. In the production of the organic semiconductor film, a film (thickness of about 30 μm) attached to the cover glass after peeling off the silicon substrate and the cover glass was used.

In the manufacturing method of this example, first, a P6T film is placed on the support base 12 disposed on the heater 11, and two glass spacers 14a and 14b having a thickness of 145 μm are formed on both ends of the P6T film on the support base 12. The substrate 13 was placed on the two glass spacers 14a and 14b. Next, the heater 11 sublimates the P6T on the support base 12 by heating at a heater temperature of 370 ° C. for 1 hour in an air atmosphere at atmospheric pressure, and on the surface of the silicon substrate with an oxide film located above the P6T film, A crystal film of P6T, which is an organic semiconductor film, was formed.
FIG. 9 shows a microscopic image of the crystal film of P6T obtained by the manufacturing method of Example 2. From this image, it was found that a highly oriented film was obtained.

(Example 3)
A P6T crystal film was manufactured in the same manner as in Example 2 except that a spacer having a thickness of 290 μm was used and a silicon substrate with an oxide film having a thickness of 2.3 mm × 20 mm was used.
FIG. 10 shows a microscopic image of the crystal film of P6T obtained by the manufacturing method of Example 3. From this image, it was found that a highly oriented film was obtained.

Example 4
Example 4 is an example corresponding to the second embodiment, and a cover glass of 18 mm × 18 mm is used as the support base 12, and the compound (1, 4) represented by the above chemical formula (19) is used as the organic semiconductor compound A. A film of bis (5′-phenylthiophen-2′-yl) benzene (hereinafter referred to as AC5) was used, and a 10 mm × 10 mm silicon substrate with an oxide film was used as the substrate 13.
The AC5 film was prepared as follows. First, a 6.5 mm × 18 mm silicon substrate was placed on the heater, about 5 mg of AC5 powder was placed thereon, and a cover glass of 18 mm × 18 mm was placed on the AC5 powder. Next, AC5 powder was heated to a melting point of 306 ° C. and melted, and then cooled to room temperature to form a film. In the production of the organic semiconductor film, a film (thickness of about 30 μm) attached to the cover glass after peeling off the silicon substrate and the cover glass was used.

In the manufacturing method of this example, first, an AC5 film is placed on the support base 12 disposed on the heater 11, and two spacers 14a and 14b having a thickness of 150 μm are disposed on both ends of the AC5 on the support base 12, The substrate 13 was placed on the two glass spacers 14a and 14b at both ends. Next, the heater 11 causes the AC5 on the support 12 to be sublimated by heating at 220 ° C. for 1 hour in an air atmosphere at atmospheric pressure, and on the surface of the silicon substrate with an oxide film located above the AC5 film, A crystal film of AC5 which is an organic semiconductor film was formed.
FIG. 11 shows a microscopic image of a crystal film of AC5 obtained by the manufacturing method of Example 4.

(Example 5)
An AC5 crystal film was produced in the same manner as in Example 4 except that the heater temperature was 230 ° C. FIG. 12 shows a microscopic image of a crystal film of AC5 obtained by the manufacturing method of Example 5.

(Example 6)
An AC5 crystal film was produced in the same manner as in Example 4 except that the heater temperature was 240 ° C. and a silicon substrate with an oxide film of 8.5 mm × 19 mm was used. FIG. 13 shows a microscopic image of the crystal film of AC5 obtained in Example 6.

(Example 7)
An AC5 crystal film was produced in the same manner as in Example 4 except that the heater temperature was 250 ° C., and a silicon substrate with an oxide film was 7.5 mm × 19 mm. FIG. 14 shows a microscopic image of the crystal film of AC5 obtained in Example 7.

(Example 8)
An AC5 crystal film was produced in the same manner as in Example 4 except that the heater temperature was 260 ° C. and a silicon substrate with an oxide film was 10 mm × 18 mm. FIG. 15 shows a microscopic image of the crystal film of AC5 obtained by the production method of Example 8.

From the microscopic images shown in FIGS. 11 to 15, it was confirmed that any hexagonal crystal was present and a characteristic crystal plane appeared in the AC5 crystal. Also, in any of the examples, it has been found that a crystal film having a high orientation with a size of several hundred μm can be produced.
Moreover, it turned out that the quantity of the organic-semiconductor film obtained becomes small, so that heating temperature becomes low from the result of Examples 4-8.

Example 9
Example 9 is an example corresponding to the second embodiment, and a cover glass of 18 mm × 18 mm is used as the support base 12, and the compound (2, 5) represented by the above chemical formula (17) is used as the organic semiconductor compound A. A film of bis (4-biphenylyl) -2,2 ′: 5 ′, 2 ″ -terthiophene (hereinafter referred to as BP3T), and a silicon substrate with an oxide film of 3.5 mm × 22 mm as the substrate 13 Was used.
The BP3T film was prepared as follows. First, a 7 mm × 18 mm silicon substrate was placed on the heater disposed on the heater 11, 3.95 mg of BP3T powder was placed thereon, and a cover glass of 18 mm × 18 mm was placed on the BP3T powder. Next, the BP3T powder was heated to a melting point of 388 ° C. and melted, and then cooled to room temperature to form a film. In the production of the organic semiconductor film, a film (thickness of about 20 μm) attached to the cover glass after peeling off the silicon substrate and the cover glass was used.

In the manufacturing method of this example, first, a BP3T film is placed on the support base 12, two glass spacers 14a and 14b having a thickness of 145 μm are disposed on both ends of the BP3T film, and two spacers 14a, 14a, The substrate 13 was placed on 14b. Next, the heater 11 sublimates the BP3T on the support base 12 by heating at a heater temperature of 330 ° C. for 1 hour in an atmospheric air atmosphere, and on the surface of the silicon substrate with an oxide film located above the BP3T film, A crystal film of BP3T, which is an organic semiconductor film, was formed.
FIG. 16 shows a microscopic image of the BP3T crystal film obtained by the manufacturing method of Example 9. The average crystal size determined from this microscopic image was 100 μm. Moreover, the obtained crystal film had high orientation.

(Example 10)
A BP3T crystal film was manufactured in the same manner as in Example 9 except that the heating time of BP3T was 3 hours, and a silicon substrate with an oxide film of 4.0 mm × 22 mm was used. FIG. 17 shows a microscopic image of the BP3T crystal film obtained by the manufacturing method of Example 10. The average crystal size determined from this microscopic image was 300 μm. Moreover, the obtained crystal film had high orientation.

(Example 11)
A BP3T crystal film was manufactured in the same manner as in Example 9 except that the heating time of BP3T was set to 7 hours and a silicon substrate with an oxide film of 2.5 mm × 22 mm was used. FIG. 18 shows a microscopic image of the crystal film of BP3T obtained by the manufacturing method of Example 11. The average crystal size determined from this microscopic image was 400 μm. Moreover, the obtained crystal film had high orientation.

  As shown in Examples 9 to 11, it was found that the longer the heating time, the larger the average crystal size.

It is a figure explaining the 1st example of an embodiment of a manufacturing method of an organic semiconductor film of the present invention. In the example of embodiment shown in FIG. 1, it is the figure which expanded the part which a board | substrate contacts with a powdery organic-semiconductor compound. It is a figure explaining the 2nd Embodiment of the manufacturing method of the organic-semiconductor film of this invention. It is the figure which expanded the part which a board | substrate contacts to a film-form organic-semiconductor compound. 2 is a microscopic image of an organic semiconductor film in Example 1. FIG. It is an image of the state which rotated the microscope image shown in FIG. 5 45 degree | times. 2 is a polarization microscope image of an organic semiconductor film in Example 1. FIG. It is an image of the state which rotated the polarization microscope image shown in FIG. 7 45 degree | times. 3 is a microscopic image of an organic semiconductor film in Example 2. 6 is a microscopic image of an organic semiconductor film in Example 3. 6 is a microscopic image of an organic semiconductor film in Example 4. 6 is a microscopic image of an organic semiconductor film in Example 5. 7 is a microscopic image of an organic semiconductor film in Example 6. FIG. 10 is a microscopic image of an organic semiconductor film in Example 7. 10 is a microscopic image of an organic semiconductor film in Example 8. 10 is a microscopic image of an organic semiconductor film in Example 9. It is a microscope image of the organic-semiconductor film in Example 10. It is a microscope image of the organic-semiconductor film in Example 11.

Explanation of symbols

11 Heater 12 Support stand 13 Substrate 14a, 14b Spacer A, B, C Organic semiconductor compound N Gap

Claims (5)

Tetracene, pentacene, quaterphenyl, quinquephenyl, sexual phenyl, thiophene-phenylene co-oligomer, compound represented by the following chemical formula (6), compound represented by the following chemical formula (7), represented by the following chemical formula (8) An organic semiconductor film manufacturing method for forming an organic semiconductor film on a surface of a substrate by vapor phase growth using an organic semiconductor compound selected as a raw material as a raw material,
The organic semiconductor compound is placed on a support base, after which the organic semiconductor compound and the surface of the substrate placed the substrate so as to face with a gap of 10μm~1cm is formed between the organic semiconductor compound, pressure 10 ^- An organic semiconductor film manufacturing method comprising forming an organic semiconductor film on a surface of a substrate by heating and sublimating an organic semiconductor compound in an atmosphere of ² Pa to 10 ⁶ Pa.

The method for producing an organic semiconductor film according to claim 1, wherein when the organic semiconductor compound is heated, the substrate and a part of the organic semiconductor compound are brought into contact with each other.   The method for producing an organic semiconductor film according to claim 2, wherein the heating temperature of the organic semiconductor compound is set to be equal to or lower than the melting point of the organic semiconductor compound.   The method for producing an organic semiconductor film according to claim 1, wherein a gap is provided between the substrate and all of the organic semiconductor compound.   The method for producing an organic semiconductor film according to claim 1, wherein the atmosphere in heating the organic semiconductor compound is a nitrogen atmosphere.

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