JP2000122068A - Material for organic molecule oriented thin film and production of organic molecule oriented thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a material capable of producing a highly oriented organic molecule oriented thin film by the conventional vacuum deposition method by using a specified π-conjugate oligomer. SOLUTION: This material for an organic molecule oriented thin film comprises a π-conjugate oligomer of the formula, wherein R1-R12 are the same or different and are each H, 1-8C alkyl or optionally substituted aryl and (l), (m) and (n) are each an integer of 1-3. When the material is used, the objective highly oriented thin film is uniformly produced by vacuum deposition over a large area of a substrate even if the temperature of the substrate is room temperature and even at such a degree of vacuum and such a rate of vacuum deposition as to adapt to the conventional vacuum deposition. The organic molecule oriented thin film excellent in mass productivity is produced at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material for an organic molecular oriented thin film used for many optical, electronic, optoelectronic devices such as an optical waveguide, an optical nonlinear element, a light emitting element, a thin film transistor, an optical filter, and the like. And a method for producing an oriented organic molecule thin film.

[0002]

2. Description of the Related Art Research on π-conjugated oligomers, which are organic semiconductors having a quasi-one-dimensional conjugated system, are expected to be applied to optical waveguides, optical nonlinear devices, light-emitting devices, thin film transistors, optical filters, and the like. Has been actively conducted in recent years.

In recent years, research on these thin films has been actively conducted. If these can be arranged precisely, there is a possibility that a thin film having very large optical non-linearity and carrier mobility can be produced. Therefore, the realization of optical, electronic, and optoelectronic devices composed of highly oriented organic alignment thin films is expected.

[0004]

However, organic molecules are bound by van der Waals forces,
Due to the very small interaction, it was difficult to obtain a highly oriented thin film.

As an example of the preparation of an alignment film using organic molecules,
An attempt to prepare a thiophene hexamer oriented thin film by an organic molecular beam evaporation method is described in Jpn. J. Appl. Phys. 33, L1031 (1994). Here, the organic molecular beam deposition method is a method in which deposition is performed at a degree of vacuum of 0.1 nm / min or less at a degree of vacuum of 10 ⁻⁶ Pa or less that cannot be reached by a normal vacuum deposition apparatus. Using this method, a highly oriented thin film can be obtained, but the deposition rate needs to be extremely slow, so that it takes time to prepare the oriented film, and expensive equipment must be used to realize a high vacuum. Must
There was a problem that the cost would be high.

Recently, pentacene (IEEE Electron D)
evice Lett. 18, 87 (1997)) and dithienothiophene (A
It has been reported that a thin film with high orientation was obtained in a structure having an aromatic polycyclic ring and a heterocyclic ring such as ppl. Phys. Lett. 71, 3871 (1997). The carrier mobility of these thin films is 0.03 to 0.7 cm ² / V · s, which is a very large value among organic films. However, in order to catch up with the mobility of a-Si (amorphous silicon), it is necessary to realize a mobility higher by about one to two orders of magnitude. It is necessary to increase the interaction and accelerate the carrier transfer between molecules.

[0007] The present invention has been made in view of the above points, and an object thereof is to make it possible to produce a highly oriented organic molecular oriented thin film by an ordinary vacuum evaporation method, not by an organic molecular beam evaporation method. It is another object of the present invention to provide a material and a method for producing an organic molecular oriented thin film which is inexpensive and excellent in mass productivity using the material.

[0008]

Means for Solving the Problems In order to solve the above-mentioned problems, a material for an organic molecular oriented thin film of the present invention has the following general formula (I): (Wherein, R ^{1 to} R ¹² are the same or different and are each a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or an aryl group which may be substituted, and 1 to m are each an integer of 1 to 3 ) Is characterized by comprising a π-conjugated oligomer represented by the formula:

Further, the material for an organic molecular oriented thin film of the present invention has the following general formula (II): (Wherein, R ^{13 to} R ²⁴ are the same or different and are each a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or an aryl group which may be substituted, and o to q are integers of 1 to 3, respectively. ) Is characterized by comprising a π-conjugated oligomer molecule represented by the formula:

Further, the material for an organic molecular oriented thin film of the present invention has the following general formula (III): (Wherein, R ^{25 to} R ³⁶ are the same or different and are each a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or an aryl group which may be substituted, and rt is an integer of 1 to 3, respectively) ) Is characterized by comprising a π-conjugated oligomer molecule represented by the formula:

Furthermore, the material for an organic molecular oriented thin film of the present invention has the following general formula (IV): (Wherein, R ³⁷ and R ³⁸ are the same or different and are each a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or an aryl group which may be substituted, and X ¹ and X ² are the same or different, The following formula, Wherein Y ¹ to Y ⁷ are the same or different, and each represents a sulfur atom, an oxygen atom or a nitride NR ^a (R ^a is a hydrogen atom, a chlorine atom, An alkyl group or an aryl group which may be substituted.)
It is. ).

Furthermore, the material for an organic molecular oriented thin film of the present invention has the following general formula (V): (Wherein, R ³⁷ and R ³⁸ are the same as described above;
X ^{3 to} X ⁵ are the same as or different from each other; Wherein Y ¹ to Y ⁷ are the same as described above. ).

Further, the material for an organic molecular oriented thin film of the present invention has the following general formula (VI): (Wherein, R ³⁷ and R ³⁸ are the same as described above;
X ^{6 to} X ⁹ are the same or different, respectively, Wherein Y ¹ to Y ⁷ are the same as described above. ).

Further, in order to solve the above-mentioned problems, a method for producing an oriented organic molecule thin film of the present invention is a method for producing an oriented organic molecule thin film comprising the above-mentioned π-conjugated oligomer or π-conjugated molecule. The film is formed by a vapor deposition method.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The π-conjugated oligomer or π-conjugated molecule of the material for an organic molecular oriented thin film of the present invention is represented by the following chemical formulas (I-1 to 20), (II-1 to 10), (III-1) ~ 1
2), (IV-1 to 11), (V-1 to 4) and (VI-
Specific examples are shown in (1) and (2).

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

In the method for producing an oriented organic molecule thin film of the present invention, a film is formed by a vacuum evaporation method using the above-mentioned π-conjugated oligomer or π-conjugated molecule. In such a vacuum evaporation method, for example, a substrate such as quartz is placed in a resistance heating evaporation apparatus, and the inside of a vacuum chamber is preferably 1 × 10 ^{−7 to} 5 × 10
^The pressure is reduced to ⁻³ Pa. Further, the temperature of the crucible is heated so that the growth rate is preferably 0.05 to 2 nm / s. The film thickness is preferably in the range from 0.5 to 300 nm.

[0024]

EXAMPLE 1 Using quartz as a substrate, the substrate was placed in a resistance heating evaporation apparatus to form a film of the compound of formula (I-11). During film formation, the pressure in the vacuum chamber was reduced to 5 × 10 ⁻⁴ Pa. Heating the temperature of the crucible so that the growth rate becomes 0.3 nm / s,
A film was formed to a thickness of 50 nm.

Example 2 An organic thin film was prepared in the same manner as in Example 1 except that the compound of the formula (I-11) was replaced by the compound of the formula (II-1).

Example 3 An organic thin film was prepared in the same manner as in Example 1 except that the compound of the formula (I-11) was replaced by the compound of the formula (III-1).

Example 4 An organic thin film was prepared in the same manner as in Example 1, except that the compound of the formula (I-11) was replaced by the compound of the formula (IV-1).

Example 5 An organic thin film was prepared in the same manner as in Example 1, except that the compound of the formula (I-11) was replaced by the compound of the formula (V-1).

Example 6 An organic thin film was prepared in the same manner as in Example 1, except that the compound of the formula (I-11) was replaced by the compound of the formula (VI-1).

Comparative Example 1 The compound of the formula (I-11) of Example 1 was converted to the compound of the following formula (VII-
1), An organic thin film was prepared in the same manner as in Example 1, except that the compound represented by the formula (1) was used.

Comparative Example 2 The compound of the formula (I-11) of Example 1 was converted to the compound of the following formula (VII-
2), An organic thin film was prepared in the same manner as in Example 1 except that the compound was replaced with the compound of Example 1.

Comparative Example 3 The compound of the formula (I-11) of Example 1 was converted to the compound of the following formula (VII-
3), An organic thin film was prepared in the same manner as in Example 1 except that the compound was replaced with the compound of Example 1.

Comparative Example 4 The compound of the formula (I-11) of Example 1 was converted to the compound of the following formula (VII-
4), An organic thin film was prepared in the same manner as in Example 1 except that the compound was replaced with the compound of Example 1.

Comparative Example 5 The compound of the formula (I-11) of Example 1 was converted to the compound of the following formula (VII-
5), An organic thin film was prepared in the same manner as in Example 1 except that the compound was replaced with the compound of Example 1.

Comparative Example 6 The compound of the formula (I-11) of Example 1 was converted to the compound of the following formula (VII-
6), An organic thin film was prepared in the same manner as in Example 1 except that the compound was replaced with the compound of Example 1.

The orientation of the organic thin film obtained as described above was evaluated by polarized light absorption measurement. The measured ratio Ip / Is of the amount of absorption in p-polarized light to the amount of absorption in s-polarized light is shown in Tables 1 and 2 below for Examples 1 to 6 and Comparative Examples 1 to 6, respectively.
Shown in

[0037]

[Table 1]

[0038]

[Table 2]

From Tables 1 and 2, when the examples and comparative examples having the corresponding numbers are compared with each other, the value of the Ip / Is ratio of each comparative example shows that each of the comparative examples has a structure in which a vinylene group is sandwiched in the molecule. It can be seen that the ratio value of the example is clearly increased. This suggests that by sandwiching the vinylene structure between the oligomer, the aromatic polycyclic ring and the aromatic heterocyclic ring, the molecule is highly oriented and, as a result, forms an associated state.

Comparing the absorption peaks in the solution, the absorption peaks of Examples 1 to 6 and the corresponding Comparative Examples 1 to 6 are longer on the long wavelength side than the absorption peaks of the respective Comparative Examples. Existed. This indicates that the conjugate length of the molecule was increased by sandwiching the vinylene group in the molecule.

Further, semi-empirical molecular orbital calculations (MOPAC
93: According to Stewart (Fujitsu), the value of the formation energy with respect to the torsion angle of thiophene is shown in FIG. there were. On the other hand, the thermal energy at room temperature (300 K) is equivalent to 0.6 kcal / mol. Therefore, FIG. 1 shows that rotation can occur even at room temperature when a thiophene group or a phenylene group is interposed, but hardly occurs when a vinylene group is interposed. This means that the torsion angle of the molecular structure sandwiching the vinylene group is less likely to change than other structures.

Furthermore, since the generation energy of the molecular structure to which the vinylene group is bonded is smallest when the twist angle is 0 °, it can be seen that this structure is originally stable with little twist. In other words, the molecular structure sandwiching the vinylene group has a very good flatness of the molecular skeleton, and therefore, the above-mentioned structure can be said to be a structure suitable for producing a molecular alignment film, in which molecules are easily arranged even during evaporation. .

From the above results, by sandwiching a vinylene group in a molecule, a highly oriented crystalline thin film can be obtained while increasing the conjugation length of the molecule, and the superiority of the present invention is apparent.

The chemical formula (I-1 to 10, 12 to 12)
20), (II-2 to 10), (III-2 to 12), (IV
-2 to 11), (V-2 to 4), and organic molecules having the molecular structures shown in (VI-2), the same effect was obtained.

[0045]

The thiophene oligomer derivative, phenylene oligomer derivative, organic molecule oriented thin film material in which a vinylene group is interposed between aromatic polycycles and aromatic heterocycles according to the present invention, while increasing the molecular conjugated system. Even if a normal vacuum deposition method is used, a highly oriented oriented thin film can be obtained.

It has also been found that the mobility of carriers increases when molecules are oriented (for example, see JA
115, 8716 (1993)), it is expected that a very high carrier mobility can be achieved by using the molecular alignment film according to the present invention for an active layer of a thin film transistor.

Further, by using the material for an organic molecular oriented thin film of the present invention, a highly oriented thin film can be obtained even at a substrate temperature of room temperature or at a degree of vacuum and a vapor deposition rate that are used in ordinary vacuum vapor deposition. Can be produced uniformly in a large area. Therefore, it is possible to produce an organic molecular oriented thin film which is low in cost and excellent in mass productivity.

[Brief description of the drawings]

FIG. 1 shows (a) a vinylene group,
It is explanatory drawing which shows the torsion angle dependence with the adjacent thiophene of the formation energy of the structure which sandwiched the (b) thiophene group and the (c) phenylene group between thiophene dimers.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C30B 29/54 C30B 29/54 H01L 51/00 C07D 333/08 // C07D 333/08 333/18 333/18 519 / 00 519/00 311 311 H01L 29/28 H01L 29/786 29/78 618B

Claims (7)

[Claims] 1. A compound represented by the following general formula (I): (Wherein, R ^{1 to} R ¹² are the same or different and are each a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or an aryl group which may be substituted, and 1 to m are each an integer of 1 to 3 A material for an organic molecular oriented thin film, comprising a π-conjugated oligomer molecule represented by the formula: 2. The following general formula (II): (Wherein, R ^{13 to} R ²⁴ are the same or different and are each a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or an aryl group which may be substituted, and o to q are integers of 1 to 3, respectively. A material for an organic molecular oriented thin film, comprising a π-conjugated oligomer molecule represented by the formula: 3. The following general formula (III): (Wherein, R ^{25 to} R ³⁶ are the same or different and are each a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or an aryl group which may be substituted, and rt is an integer of 1 to 3, respectively) A material for an organic molecular oriented thin film, comprising a π-conjugated oligomer molecule represented by the formula: 4. The following general formula (IV): (Wherein, R ³⁷ and R ³⁸ are the same or different and are each a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or an aryl group which may be substituted, and X ¹ and X ² are the same or different, The following formula, Wherein Y ¹ to Y ⁷ are the same or different, and each represents a sulfur atom, an oxygen atom or a nitride NR ^a (R ^a is a hydrogen atom, a chlorine atom, An alkyl group or an aryl group which may be substituted.)
It is. A material for an organic molecular oriented thin film, comprising a π-conjugated molecule represented by the following formula: 5. The following general formula (V): (Wherein, R ³⁷ and R ³⁸ are the same as described above;
X ^{3 to} X ⁵ are the same as or different from each other; Wherein Y ¹ to Y ⁷ are the same as described above. A material for an organic molecular oriented thin film, comprising a π-conjugated molecule represented by the following formula: 6. The following general formula (VI): (Wherein, R ³⁷ and R ³⁸ are the same as described above;
X ^{6 to} X ⁹ are the same or different, respectively, Wherein Y ¹ to Y ⁷ are the same as described above. A material for an organic molecular oriented thin film, comprising a π-conjugated molecule represented by the following formula: 7. A method for producing an organic molecular oriented thin film using the material for an organic molecular oriented thin film according to claim 1, wherein the organic molecule is formed by a vacuum deposition method. A method for producing an oriented thin film.