JP2006131801A - Conductive organic molecule and electronic device using the same, and methods of manufacturing conductive organic molecule and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new conductive organic molecule effective for realizing an organic electronic device high in characteristics, and a method of manufacturing the new conductive organic molecule and a method of manufacturing the electronic device using the same. <P>SOLUTION: The manufacturing method of the conductive organic molecules containing following repeating units (1), includes a process for alternately supplying a first organic molecule shown by following formula (2) and a second organic molecule shown by formula (3) onto a substrate (i) to react with each other. Formula (1) -R<SP>1</SP>-CH=N-R<SP>2</SP>-N=CH-, formula (2) OHC-R<SP>1</SP>-CHO, formula (3) H<SB>2</SB>N-R<SP>2</SP>-NH<SB>2</SB>, [in formulae (1)-(3), R<SP>1</SP>and R<SP>2</SP>are each independently a group having π electron conjugated chain of which the principal chain length is in the range of 0.65 nm-4.0 nm, as a principal chain]. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a conductive organic molecule, an electronic device using the same, and a method for manufacturing the conductive organic molecule and the electronic device.

  Now that the limits of microfabrication in silicon integrated circuits are becoming a real problem, the creation of new key materials to replace silicon is an extremely important research issue for acquiring next-generation industry initiatives. Molecular devices are attracting attention as one approach to solving this problem.

  The functionality exhibited by organic molecules originates from the electric field response of π electrons delocalized within the molecule and increases with increasing delocalization length. Therefore, a conjugated polymer having π electrons that are delocalized one-dimensionally along the molecular chain is expected to have further superior functionality compared to a low molecule. In reality, however, there have been few reports on the realization of performance expected from the molecular structure of conjugated polymers as macroscopic characteristics. There are three main reasons why the expected performance cannot be obtained from the molecular structure.

1. Insufficient material purification.
2. A completely extended molecular chain is not achieved and the effective conjugated chain length is short.
3. The ordered structure such as molecular chain orientation and alignment is not strictly controlled.

  These problems are deeply related to the method for synthesizing conjugated polymers, and are difficult to solve as long as commonly used synthesis methods are used. For example, a conjugated polymer obtained by solution polymerization has a distribution in molecular weight and a molecular chain has a random coil structure. As a result, the effective conjugated chain length is shorter than the molecular chain length and has a wide distribution. Further, it is not easy thermodynamically to rearrange the molecular chain from the random coil structure once formed in the solution to the linear extended structure.

Recently, a method of forming a conductive polymer by reacting terephthalaldehyde and p-phenylenediamine has been proposed (Non-patent Documents 1 and 2).
MS Weaver, DDC Bradley, Synthetic Metals, 1996, p.61-66 Tetsuzo Yoshimura, et al., Applied Physics Letters, Vol. 60, No. 3, 1992, p.268-270

  However, the compounds used in the above prior art sometimes fail to obtain sufficient characteristics when formed on a substrate.

  In view of such circumstances, an object of the present invention is to provide a novel conductive organic molecule effective for realizing an organic electronic device having high characteristics and an electronic device using the same. Another object of the present invention is to provide a novel method for producing a conductive organic molecule effective for realizing an organic electronic device having high characteristics and a method for producing an electronic device using the same.

In order to achieve the above object, a production method of the present invention is a method for producing a conductive organic molecule comprising the following repeating structural unit (1), and is represented by the following formula (2) on a substrate: The process includes supplying the first organic molecule and the second organic molecule represented by the following formula (3) alternately to react with each other.
(1) —R ¹ —CH═N—R ² —N═CH—
(2) OHC—R ¹ —CHO
(3) H ₂ N—R ² —NH ₂
[In formulas (1) to (3), R ¹ and R ² are each independently a group having a main chain of a π-electron conjugated chain having a main chain length in the range of 0.65 nm to 4.0 nm. ]

The repeating structural unit of the formula (1) can be regarded as substantially the same as the following repeating unit (1 ′).
(1 ′) —N═CH—R ¹ —CH═N—R ² —

  Moreover, the method of this invention for manufacturing an electronic device includes the process of forming a conductive organic molecule on a board | substrate by the manufacturing method of the said invention.

Moreover, the electroconductive organic molecule of this invention contains the following repeating structural units (1).
(1) —R ¹ —CH═N—R ² —N═CH—
[Wherein, R ¹ and R ² are each independently a group having a main chain of a π-electron conjugated chain having a main chain length in the range of 0.65 nm to 4.0 nm. ]

  Moreover, the electronic device of the present invention is an electronic device containing a first conductive organic molecule, and the first conductive organic molecule is the conductive organic molecule of the present invention.

  According to the present invention, conductive organic molecules having high linearity can be obtained, and in particular, conductive organic molecules bonded to the substrate in an upright state with respect to the substrate can be obtained. In the present invention, it is possible to obtain conductive organic molecules having various characteristics by changing the kind of π electron conjugated chain of the monomer to be reacted. By using such conductive organic molecules, an electronic device having high characteristics, such as an organic light emitting diode, can be realized. Furthermore, a quantum structure is formed in a single molecule and precise electronic state control is performed to realize a single molecule light emitting diode or the like.

  Embodiments of the present invention will be described below.

(Method for producing conductive organic molecules)
The manufacturing method of this invention is a manufacturing method of the electroconductive organic molecule containing the following repeating structural units (1).

[Wherein, R ¹ and R ² are each independently a group having a main chain of a π-electron conjugated chain having a main chain length in the range of 0.65 nm to 4.0 nm (the same applies hereinafter). ]

The conductive organic molecule produced by the production method of the present invention includes a molecular chain in which the structural unit (1) is repeatedly bonded. R ¹ and R ² may be the same or different. The main chain of R ¹ and R ² may be a π-electron conjugated chain. For example, a —CH═CH— group, a —C≡C— group, an aromatic ring (including a heterocyclic ring) may be conjugated alone or in combination. It is a combination. The side chain may not be bound to the main chain, or the side chain may be bound. By selecting appropriate main and side chains, conductive organic molecules with various properties can be produced. The chain length of the main chain is more preferably in the range of 1.0 nm to 3.0 nm.

In this manufacturing method, a first organic molecule represented by the following formula (2) and a second organic molecule represented by the following formula (3) are alternately supplied onto a substrate to react with each other. Including a step (step (i)).
(2) OHC—R ¹ —CHO
(3) H ₂ N—R ² —NH ₂
[Wherein, R ¹ and R ² are the same as R ¹ and R ² described above, respectively. ]

  An example of the first organic molecule is shown in FIG. 1, and an example of the second organic molecule is shown in FIG. In the production method of the present invention, the molecular chain is elongated by repeating the cycle of alternately supplying the first organic molecule and the second organic molecule. The first and second organic molecules to be supplied on the substrate are common in all cycles in principle. However, different first and second organic molecules are supplied for each cycle as long as the effect of the present invention is obtained. May be.

  When conductive organic molecules are formed on a substrate using organic molecules having a short main chain length, it is difficult to manufacture conductive organic molecules that stand up in a state where the angle formed by the substrate surface and the chain axis is large. On the other hand, in the present invention, since organic molecules having a main chain chain length within a predetermined range are used, conductive organic molecules having a large angle formed by the substrate surface and the chain axis can be formed on the substrate. .

R ¹ and R ² preferably have a value of [main chain length] / [width in a direction perpendicular to the chain axis] (hereinafter sometimes referred to as “aspect ratio”) in the range of 3 to 12. . Thus, by using a molecule having a high aspect ratio, the angle formed by the substrate surface and the chain axis can be particularly increased. The aspect ratio is more preferably in the range of 5-10.

As an example of a group having a preferred aspect ratio, the above R ¹ and R ² may each independently be a group represented by the following formula (4) or formula (5).

  In the manufacturing method of the present invention, the substrate is a silicon substrate, and before the step (i), (a) a step of bonding an amino group to a silicon atom on the surface of the silicon substrate; A step of reacting the amino group with the first organic molecule by supplying one organic molecule.

Step (a) can be performed by reacting silicon atoms on the surface of the silicon substrate with NH ₂ radicals. For example, it can be performed by generating NH ₂ radicals on the surface of a silicon single crystal substrate whose surface is a (111) plane. The NH ₂ radical can be formed by, for example, thermal decomposition of ammonia. Alternatively, the step (a) can be performed by irradiating the surface of the silicon substrate with ultraviolet rays to form dangling bonds on the silicon surface and bringing it into contact with ammonia gas.

  In the step (b), by supplying the first organic molecule to the silicon substrate surface, the amino group on the substrate surface is reacted with the aldehyde group of the first organic molecule. Also in the step (b), the main chain length and aspect ratio of the first organic molecule are important. After step (b), step (i) is performed to form conductive organic molecules.

  By performing the above steps (a) and (b), conductive organic molecules can be formed on the silicon substrate surface in a state where the angle formed by the silicon substrate surface and the chain axis is large. Since the conductive organic molecule is bonded to the silicon substrate via an azomethine bond (—N═CH—), the conductive organic molecule has good conductivity with the silicon substrate. In the step (b), a conductive organic molecule having an aldehyde group or a carbonyl halide group and an amino group or an aldehyde group may be used instead of the first organic molecule.

  In the production method of the present invention, the substrate temperature when supplying organic molecules onto the substrate is preferably close to the evaporation temperature of the organic molecules to be supplied, for example, [evaporation temperature −50 ° C.] or higher. It is the above temperature. According to this configuration, unnecessary organic molecules out of the organic molecules supplied onto the substrate are released into the gas phase, so that conductive organic molecules can be efficiently formed as designed. The substrate temperature is preferably set to, for example, [evaporation temperature + 50 ° C.] or less. According to this configuration, the organic molecules supplied on the substrate can be reacted efficiently.

  In the production method of the present invention, a conductive organic molecule having an arbitrary chain length can be formed by repeating a cycle in which the first organic molecule and the second organic molecule are alternately reacted. Although there is no limitation in particular in the chain length of an electroconductive organic molecule, in an example, it is the range of 1.5 nm-1 micrometer.

(Electronic device manufacturing method)
The method for manufacturing an electronic device of the present invention includes a step of forming conductive organic molecules on a substrate by the method for manufacturing conductive organic molecules of the present invention. Various organic electronic devices can be realized by forming a layer made of conductive organic molecules by the above manufacturing method and then laminating other organic molecular layers. It is also possible to realize various single-molecule elements by forming conductive organic molecules by the above manufacturing method and then combining other organic molecules.

  Hereinafter, an example of the manufacturing method of the present invention will be described. However, the following manufacturing method is an example, and the present invention is not limited to this.

(First example)
In the first example, an example of a method for forming a light emitting element will be described. First, the Si (111) substrate was brought into contact with 5% hydrofluoric acid (hydrofluoric acid) for 5 minutes to treat the surface with hydrogen termination, and then brought into contact with a 50 mM aqueous ammonium sulfite solution to flatten it to the atomic level. An Si (111) plane is obtained. Next, the treated Si substrate is placed in a chamber, and the ammonia gas flow rate is maintained at 50 sccm and the atmospheric pressure is maintained at 2 torr (about 266 Pa). In this state, the surface of the hydrogen-terminated substrate is irradiated with ultraviolet rays from a high-pressure mercury lamp (100 W) through a sapphire window for 24 hours. In this way, a silicon substrate having an amino group bonded to the surface is produced.

  Next, as shown in FIG. 3, the obtained silicon substrate 10 is set on the substrate holder 21 in the chamber of the vacuum evaporation apparatus 20. In the chamber, a vapor deposition source 22 filled with 1,4-bis (4-formylstyryl) benzene, which is a first organic molecule, and a second organic molecule. A vapor deposition source 24 filled with 4,4 ″ -diamino-p-terphenyl (4,4 ″ -Diamino-p-terphenyl) as a molecule is disposed.

Next, the chamber 21 is evacuated using a turbo molecular pump, and when the pressure reaches 1 × 10 ⁻⁶ Torr (about 1.3 × 10 ⁻⁴ Pa), the substrate holder 21 is heated to 200 ° C. Next, the vapor deposition source 22 is heated to 260 ° C. to evaporate 1,4-bis (4-formylstyryl) benzene, which is the first organic molecule, and the heating is stopped after a predetermined time. Of the first organic molecules that have reached the substrate surface, the molecules that have reacted with the amino groups on the substrate surface are fixed to the substrate surface by chemical bonding, but the molecules that have not reacted are shown in FIG. Re-evaporate. In this manner, a monomolecular layer of the first organic molecule is formed on the substrate.

  Next, the evaporation source 23 is heated to 200 ° C. to evaporate 4,4 ″ -diamino-p-terphenyl, which is the second organic molecule, and the heating is stopped after a certain period of time. The fixed aldehyde group of the first organic molecule and one of the amino groups of the second organic molecule undergo a dehydration condensation reaction to form an azomethine bond, which is highly reactive. This reaction proceeds easily even at room temperature, and as a result, the molecular chain of the conductive organic molecule extends as shown in FIG.

  By repeating the cycle of alternately supplying the first organic molecule and the second organic molecule 30 times, a polyazomethine thin film having a thickness of about 100 nm can be obtained. Finally, a device is obtained by depositing a patterned metal electrode using a shadow mask. As the metal for the electrode, Au, Ag, Al, Ca, Mg, Na, Li, and alloys thereof can be used.

(Second example)
In the second example, an example of a method of forming a pn junction type light emitting diode will be described. First, as shown in FIG. 5A, a silicon substrate having an amino group bonded to the substrate surface is produced by the same method as in the first example. Next, as shown in FIG. 6, the silicon substrate 10 is set on the substrate holder 21 in the chamber of the vacuum evaporation apparatus 20. The vacuum deposition apparatus 20 includes four deposition sources 22 to 25. The four vapor deposition sources include two types of monomers for generating polyazomethine that functions as a p-type conjugated polymer, and two types for generating polyoxadiazole that functions as an n-type conjugated polymer. Each monomer is filled.

  In the same manner as in the first example, the first organic molecule (1,4-bis (4-formylstyryl) benzene) and the second organic molecule (4,4 ″ -diamino-p-terphenyl) are combined. The cycle of alternating deposition is repeated 15 times (FIG. 5 (b)) In this way, a polyazomethine thin film (film thickness of about 50 nm) that functions as a p-type polymer is produced. Are cooled to room temperature.

  Next, polyoxadiazole that functions as an n-type polymer is formed. The synthesis scheme is shown in FIG. Polyoxadiazole is obtained by heating polydicarbohydrazide produced by polycondensation reaction of aromatic dicarbonyl dichloride and aromatic dicarbohydrazide to 300 ° C. or higher in vacuum. That is, by setting the substrate temperature to 300 ° C. or higher, the reaction from the monomer to polyoxadiazole proceeds.

  Note that the main chain of the organic molecule used in this reaction is not limited to an aromatic group, and may be a π-electron conjugated chain. An example of a dicarbonyl dichloride compound applicable to this reaction is shown in FIG. An example of a dicarbohydrazide compound applicable to this reaction is shown in FIG.

  In the formation of polyoxadiazole, first, the substrate temperature is raised to 300 ° C. Then, the evaporation source filled with biphenyl-4,4 ″ -dicarbonyl dichloride is heated to 115 ° C. and evaporated. At this time, among the monomers (Biphenyl-4,4 ″ -dicarbonyl dichloride) that have reached the substrate surface, the monomer that has reacted with the terminal amino group of the polyazomethine molecule oriented vertically is an amide bond (—NH—CO—). Monomers immobilized on the surface but not reacted re-evaporate, thus forming a layer in which one end of biphenyl-4,4 "-dicarbonyl dichloride is bonded to the end of the polyazomethine molecule. By this operation, the outermost surface of the film is terminated by a carbonyl chloride group.

  Next, a vapor deposition source filled with biphenyl-4,4 ″ -dicarbohydrazide is heated to 300 ° C. and evaporated. Biphenyl-4,4 ″ -dicarbohydrazide that has reached the surface of the membrane reacts with the carbonyl chloride group on the outermost surface to form a carbohydrazide bond (—CONHNHCO—) and simultaneously undergoes dehydration cyclization to form an oxadiazole ring. In this way, a monomolecular film in which the outermost surface of the film is terminated with a carbohydrazide group is formed. Thus, biphenyl-4,4 "-dicarbonyl dichloride and biphenyl-4,4" -di The process of alternately depositing carbohydrazide is repeated 20 times to form a polyoxadiazole layer (thickness of about 50 nm) in which molecular chains are vertically oriented (FIG. 5 (c)). Conductive organic molecules shown in (d) are formed.

  Finally, a patterned metal electrode is deposited using a shadow mask to produce a device having a p-type region and an n-type region.

(Conductive organic molecules)
The conductive organic molecule of the present invention includes the following repeating structural unit (1).
(1) —R ¹ —CH═N—R ² —N═CH—
[Wherein, R ¹ and R ² are each independently a group having a main chain of a π-electron conjugated chain having a main chain length in the range of 0.65 nm to 4.0 nm. ]

This organic molecule can be produced by the production method of the present invention. Since R ¹ and R ² are the same as those described above, redundant description is omitted.

(Electronic device)
The electronic device of the present invention is an electronic device including a first conductive organic molecule, and the first conductive organic molecule is the conductive organic molecule of the present invention.

  The electronic device of the present invention may include an n-type second conductive organic molecule and function as a light emitting diode. This second conductive organic molecule is an organic molecule that exhibits n-type conductivity with respect to the first conductive organic molecule (the conductive organic molecule of the present invention).

  In the electronic device of the present invention, either one of the first and second conductive organic molecules is bonded to the silicon substrate, and the first and second conductive organic molecules stand up from the silicon substrate. Good.

  In the electronic device of the present invention, the first conductive organic molecule and the second conductive organic molecule are bonded directly or via a molecular chain, and may function as a single molecule element.

  An example of these electronic devices is the element described in the first and second examples. An organic quantum device can also be realized by using the manufacturing method of the present invention. An example of such an organic quantum device is shown in FIG.

  10 includes a p-type region 31, a barrier region 32, a recombination region 33, a barrier region 34, and an n-type region 35. The holes injected into the p-type region 31 tunnel through the barrier region 32 and reach the recombination region 33. On the other hand, the electrons injected into the n-type region 35 tunnel through the barrier region 34 and reach the recombination region 33. In the recombination region 33, holes and electrons recombine, and light is emitted. The p-type region 31 and the n-type region can be formed of the organic molecules described above. Further, the barrier region 32 can be formed of a molecular chain having no electrical conductivity, such as an aliphatic hydrocarbon. Such a single molecule device has a molecular chain length of, for example, 1 to 10 nm and a molecular width of 0.5 to 1 nm.

  The embodiments of the present invention have been described above by way of examples, but the present invention is not limited to the above-described embodiments, and can be applied to other embodiments based on the technical idea of the present invention.

  The present invention can be applied to electronic devices using organic molecules, for example, light emitting diodes and transistors.

It is a figure which shows the example of the 1st organic molecule used with the manufacturing method of this invention. It is a figure which shows the example of the 2nd organic molecule used with the manufacturing method of this invention. It is a figure which shows an example of the apparatus used with the manufacturing method of this invention. It is a figure which shows typically the process of the manufacturing method of this invention. It is a figure which shows an example of the manufacturing method of this invention. It is a figure which shows the other example of the apparatus used with the manufacturing method of this invention. It is a figure which shows the synthetic scheme of polyoxadiazole. It is a figure which shows the example of the dicarbonyl dichloride compound used with the manufacturing method of this invention. It is a figure which shows the example of the dicarbohydrazide compound used with the manufacturing method of this invention. It is a figure which shows an example of a single molecule element typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Silicon substrate 20 Vacuum deposition apparatus 21 Substrate holder 22, 23, 24, 25 Deposition source 30 Single molecule element 31 P-type area | region 32 Barrier area | region 33 Recombination area | region 34 Barrier area | region 35 N-type area | region

Claims (12)

A method for producing a conductive organic molecule comprising the following repeating structural unit (1),
(I) A step of alternately supplying a first organic molecule represented by the following formula (2) and a second organic molecule represented by the following formula (3) on the substrate to react with each other. A method for producing a conductive organic molecule.
(1) —R ¹ —CH═N—R ² —N═CH—
(2) OHC—R ¹ —CHO
(3) H ₂ N—R ² —NH ₂
[In formulas (1) to (3), R ¹ and R ² are each independently a group having a main chain of a π-electron conjugated chain having a main chain length in the range of 0.65 nm to 4.0 nm. ] ^{2. The} method for producing a conductive organic molecule according to claim 1, wherein R ¹ and R ² have a value of [main chain length] / [width in a direction perpendicular to the chain axis] in the range of 3 to 12. 3. The method for producing a conductive organic molecule according to claim 1, wherein R ¹ and R ² are each independently a group represented by the following formula (4) or formula (5).
The substrate is a silicon substrate;
Before the step (i),
(A) attaching an amino group to silicon atoms on the surface of the silicon substrate;
And (b) supplying the first organic molecule to the surface of the silicon substrate to react the amino group with the first organic molecule. Production method.   The manufacturing method of an electronic device including the process of forming a conductive organic molecule on a board | substrate by the manufacturing method of any one of Claims 1-4. A conductive organic molecule comprising the following repeating structural unit (1).
(1) —R ¹ —CH═N—R ² —N═CH—
[Wherein, R ¹ and R ² are each independently a group having a main chain of a π-electron conjugated chain having a main chain length in the range of 0.65 nm to 4.0 nm. ] 7. The conductive organic molecule according to claim 6, wherein R ¹ and R ² have a value of [main chain length] / [width in a direction perpendicular to the chain axis] in the range of 3 to 12. 8. The conductive organic molecule according to claim 6, wherein R ¹ and R ² are each independently a group represented by the following formula (4) or formula (5).
  It is an electronic device containing a 1st conductive organic molecule, Comprising: The said 1st conductive organic molecule is an electronic device which is a conductive organic molecule of any one of Claims 6-8.   The electronic device according to claim 9, comprising an n-type second conductive organic molecule and functioning as a light emitting diode.   11. One of the first and second conductive organic molecules is bonded to a silicon substrate, and the first and second conductive organic molecules are upright with respect to the silicon substrate. The electronic device described.   The electronic device according to claim 10 or 11, wherein the first conductive organic molecule and the second conductive organic molecule are bonded directly or via a molecular chain and function as a single molecule element.