JP2005021889A - Molecular thin film, functional organic thin film and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: An organic material that can be applied to more materials and has both a chemical structure of an organic material, which is a factor determining the characteristics of a thin film, and a higher order structure of the film, for example, crystallinity of molecules, that is, orientation. It is possible to produce a functional organic thin film by a simple method that can give the main skeleton part of the film forming film, and optionally the electrical, optical, electro-optical and other functionalities. It aims at providing the manufacturing method of a functional organic thin film.
SOLUTION: A first step of forming a molecular thin film 3 in which a first functional group R1 protrudes periodically on a surface of a substrate 1 and a second functional group R2 of an organic compound 4 are formed on the surface of the molecular thin film 3. Provided is a method for producing a functional organic thin film, which includes a second step of forming an organic thin film 5 in which an organic compound is bonded and periodically arranged on a molecular thin film by reacting with the first functional group R1. To do.
[Selection] Figure 1

Description

  The present invention relates to a molecular thin film, a functional thin film, and a method for producing the same, and more particularly to a method for producing a functional thin film obtained by bonding an organic compound on a molecular thin film having a periodic structure.

  In recent years, it has become easier to process semiconductors using inorganic materials, can handle larger devices, can be expected to reduce costs due to mass production, and can be expected to have various functions. Attempts have been made to apply to semiconductor devices such as photoelectric conversion elements, organic light emitting elements, insulating films, resist films, and nonlinear optical elements.

In particular, it is known that a TFT having a large mobility can be manufactured by using an organic compound containing a π-electron conjugated molecule. As this organic compound, pentacene has been reported as a representative example (for example, IEEE Electron Device).
Lett, 1997, 18, 606-608). Here, when an organic semiconductor layer is formed using pentacene and a TFT is formed using this organic semiconductor layer, a field effect mobility is 1.5 cm ² / Vs, and a TFT having a mobility higher than that of amorphous silicon is constructed. It has been reported that this is possible.

  However, when producing an organic compound semiconductor layer for obtaining a field effect mobility higher than that of amorphous silicon as shown above, a vacuum process such as resistance heating vapor deposition or molecular beam vapor deposition is required. Becomes complicated, and a film having crystallinity can be obtained only under certain specific conditions. Further, since the adsorption of the organic compound film on the substrate is physical adsorption, there is a problem that the adsorption strength of the film to the substrate is low and the film is easily peeled off. Furthermore, in order to control the molecular orientation of the organic compound in the film to some extent, the orientation control by rubbing or the like is usually performed in advance on the substrate on which the film is formed. It has not yet been reported that the molecular alignment and orientation of the compound at the interface between the organic compound and the substrate can be controlled.

  On the other hand, regarding the regularity and crystallinity of the film that has a great influence on the field-effect mobility, which is a typical guideline for the characteristics of this TFT, in recent years, self-assembled films using organic compounds have been easy to manufacture. Research has been made on the use of the membrane.

  A self-assembled film is a film in which a part of an organic compound is bonded to a functional group on a substrate surface, has very few defects, and has high order, that is, crystallinity. Since this self-assembled film has a very simple manufacturing method, it can be easily formed on a substrate. Usually, as a self-assembled film, a thiol film formed on a gold substrate and a silicon-based compound film formed on a substrate (for example, a silicon substrate) capable of protruding a hydroxyl group on the surface by a hydrophilization treatment are known. Yes. Of these, silicon compound films are attracting attention because of their high durability. The silicon-based compound film has been conventionally used as a water-repellent coating, and has been formed using a silane coupling agent having an alkyl group having a high water-repellent effect or a fluorinated alkyl group as an organic functional group.

  However, the conductivity of the self-assembled film is determined by the organic functional group in the silicon-based compound contained in the film, but commercially available silane coupling agents contain π-electron conjugated molecules in the organic functional group. There are no compounds, so it is difficult to impart conductivity to the self-assembled film. Accordingly, there is a need for a silicon-based compound suitable for devices such as TFTs and containing a π-electron conjugated molecule as an organic functional group.

  As such a silicon compound, a compound having one thiophene ring as a functional group at the end of a molecule and a thiophene ring bonded to a silicon atom via a linear hydrocarbon group has been proposed (for example, Patent No. 1). No. 2889768: Patent Document 1). Furthermore, as a polyacetylene film, a film in which an —Si—O— network is formed on a substrate by a chemical adsorption method to polymerize a portion of an acetylene group has been proposed (for example, Japanese Patent Publication No. 6-27140: Patent). Reference 2). Further, as the organic material, a silicon compound in which a linear hydrocarbon group is bonded to the 2nd and 5th positions of the thiophene ring and the end of the linear hydrocarbon is bonded to the silanol group is used. In addition, an organic device has been proposed in which molecules are polymerized by electric field polymerization or the like to form a conductive thin film, and the conductive thin film is used as a semiconductor layer (for example, Japanese Patent No. 2507153: Patent Document 3). ). Furthermore, a field effect transistor using a semiconductor thin film whose main component is a silicon compound having a silanol group in a thiophene ring contained in polythiophene has been proposed (for example, Japanese Patent No. 2725587: Patent Document 4).

  However, although the compounds proposed above can produce a self-assembled film that can be chemically adsorbed to a substrate, the film has high orderability, crystallinity, and electrical conductivity characteristics that can be used in electronic devices such as TFTs. Could not always be produced. Furthermore, when the compound proposed above is used for the semiconductor layer of the organic TFT, there is a problem that the off-current becomes large. This is thought to be because all of the proposed compounds have bonds in the direction of the molecule and in the direction perpendicular to the molecule.

  In order to obtain high order, that is, high crystallinity, a high attractive interaction must be exerted between molecules. The intermolecular force is composed of an attractive term and a repulsion term, the former being inversely proportional to the sixth power of the intermolecular distance and the latter being inversely proportional to the twelfth power of the intermolecular distance. Therefore, the intermolecular force obtained by adding the attractive force term and the repulsive term has the relationship shown in FIG. Here, the minimum point (arrow part in the figure) in FIG. 3 is the intermolecular distance when the highest attractive force acts between molecules due to the balance between the attractive term and the repulsive term. That is, in order to obtain higher crystallinity, it is important to make the intermolecular distance as close as possible to the minimum point. Therefore, originally, in vacuum processes such as resistance heating vapor deposition and molecular beam vapor deposition, high orderliness is achieved by controlling the intermolecular interaction between π-electron conjugated molecules only under certain conditions. That is, crystallinity is obtained. Thus, it becomes possible to express high electrical conduction characteristics only with the crystallinity constructed by the intermolecular interaction.

  On the other hand, the above compound may be chemically adsorbed to the substrate by forming a two-dimensional network of Si-O-Si, and there is a possibility that ordering due to intermolecular interaction between specific long-chain alkyls may be obtained. However, since one thiophene molecule as a functional group only contributes to the π-electron conjugated system, there is a problem that the interaction between molecules is weak and the spread of the π-electron conjugated system essential for electrical conductivity is very small. there were. Even if the number of thiophene molecules, which are the above functional groups, can be increased, the factor that forms the order of the film matches the intermolecular interaction between the long-chain alkyl part and the thiophene part. It is difficult to make it.

  Furthermore, as an electrical conduction characteristic, a single thiophene molecule that is a functional group has a large HOMO-LUMO energy gap, and there is a problem that sufficient carrier mobility cannot be obtained even when used as an organic semiconductor layer in a TFT or the like. Existed.

  On the other hand, as a method for forming a thin film having crystallinity using an organic material, for example, a vacuum vapor deposition method can be mentioned. However, since the vacuum vapor deposition method requires heating in a vacuum, an organic compound that causes thermal decomposition. Can not be used.

As other methods for forming a crystalline thin film using an organic material, there are an LB method, a casting method, a chemical adsorption method using a silane coupling agent, and the like.
Here, the above-mentioned various methods will be briefly described. The casting method is a method for obtaining a thin film having crystallinity by applying a solution of a material having molecular crystals to a substrate and then evaporating the solvent to dry. .
The LB method is a method in which organic molecules having a hydrophilic group and a hydrophobic group in the molecule are developed on the water surface, and an oriented film (LB film) is scooped on the substrate.

The method of chemically adsorbing using a silane coupling agent is, for example, a method for obtaining a thin film having crystallinity by chemical adsorption by hydrolysis of a hydroxyl group on a hydrophilically treated substrate surface and a molecular end group constituting the silane coupling agent. It is crystallized by packing due to intermolecular interaction (van der Waals force) between alkyl chains (or fluoroalkyl chains) forming the main skeleton and formation of a network in which silicon atoms and oxygen atoms are formed in a network structure. A highly functional film is obtained. This method is a method using so-called self-organization in which orientation can be automatically performed by effectively utilizing the intermolecular interaction between material molecules. As an example, a method of forming an antistatic film by a chemical adsorption method has been proposed (for example, see Patent Document 5). In this method, a conductive chemisorption film is formed on the surface via a siloxane-based monomolecular film, and the conductivity is 10 ⁻⁵ S / cm or more on the surface of a substrate having a conductivity of 10 ⁻¹⁰ S / cm or less. It forms a chemisorbed film.

However, in any of the LB method and the method of chemical adsorption using a silane coupling agent, it is common to form directly on a substrate using a compound having a reactive site at the terminal. Accordingly, it is necessary that the material molecule contains a functional group having a self-organization ability before the reaction. However, the known synthesis technique for obtaining organic materials has a drawback in that the types of materials that can be used as π-electron conjugated molecules are particularly limited. This is due to the very high reactivity of the silanol group.
In general, the reactivity of silanol groups is so high that it reacts with moisture in the atmosphere. Therefore, for example, when synthesizing an organosilane compound containing an organic molecule that does not contain a π-electron conjugated molecule such as an alkyl group as an organic residue, the reaction site with a silanol group is generally activated in advance. A technique is employed in which an organosilane compound is prepared by reacting with a highly reactive silane compound such as tetrachlorosilane.

When a π-electron conjugated molecule is included, it is difficult to retain a silanol group only in the target reaction site when an organosilane compound is synthesized by the above method, and a by-product containing a silanol group in two or more reaction sites Many things are produced. This is because the reactivity is relaxed by the π-electron conjugated system even if the reaction site is activated. Furthermore, the reactivity of silanol groups is so high that it is very difficult to use product separation techniques such as recrystallization and fractional distillation at high temperatures.
In this way, it is very difficult to synthesize organosilane compounds containing π-electron conjugated molecules as organic residues, and organosilanes containing π-electron conjugated molecules having the necessary functional groups even if they can be synthesized. The compound yield is believed to be very small. Therefore, in consideration of economic efficiency and mass production, a method of reacting an organic silane compound containing a π-electron conjugated molecule with a substrate in advance is not an optimal manufacturing method.
Because of these problems, it is particularly difficult to synthesize π-electron conjugated materials, and as a better manufacturing method, it is required to separate the self-assembled film forming step and the π-electron conjugated molecule bonding process.

Thus, as a method in which the production method is composed of two steps of the self-assembled film formation step and the binding process of the second layer molecule, for example, a chemisorbed monolayer film and a method for producing the same are proposed. (For example, refer to Patent Document 6). In this method, for example, after reacting a chlorosilane compound such as SiCl ₄ with a substrate surface having or having an active hydrogen group such as a hydroxyl group or an imino group, a chlorosilane-based adsorbent having a fluoroalkyl group is reacted. This is a method for producing a monomolecular cumulative film.

  However, the above method is a production method aimed at increasing the number of reaction sites between the substrate and the silane compound, and is characterized in that the functional groups protruding from the network created as the first layer are not periodically arranged. . Therefore, when a cumulative film is formed by this method, a silane compound is required as the second layer, and thus the above problem cannot be solved. In other words, it is a manufacturing method for forming a highly self-assembled film and an organic thin film manufacturing method applicable to many substrate materials. It is necessary that the reaction site with the material protrudes periodically.

Japanese Patent No. 2889768 Japanese Examined Patent Publication No. 6-27140 Japanese Patent No. 2507153 Japanese Patent No. 2725587 JP-A-5-202210 JP-A-5-86353

  The present invention has been made in view of the above problems, and is applicable to more substrate (underlying) materials, and has a chemical structure of an organic material that is a factor that determines the characteristics of a thin film, and a higher-order structure of the film. For example, it is possible to form an organic thin film in which both the crystallinity of molecules, that is, the orientation, and the main skeleton of the molecules forming the film can have any functionality such as electrical, optical, and electro-optical properties. It is an object to provide a method for producing a functional organic thin film capable of producing a functional organic thin film that can be produced by a simple method, and a molecular thin film and a functional organic thin film obtained by this production method.

Thus, according to the present invention, the first step of forming a molecular thin film in which the first functional group protrudes periodically on the surface of the substrate,
The second functional group of the organic compound is reacted with the first functional group of the molecular thin film or the third functional group obtained by converting the first functional group, and the organic compound is bonded onto the molecular thin film to cause periodicity. A method for producing a functional organic thin film is provided, which includes a second step of forming an organic thin film formed by arranging the organic thin film. Here, “the functional group protrudes periodically” means a state in which the functional group is periodically oriented as a side chain on the surface of the molecule constituting the molecular thin film (here, the organosilane compound).

  That is, the method for producing a functional organic thin film of the present invention has a self-organizing function of a structure in which the first functional group protrudes periodically in the first step of constructing a periodically reactive site. A molecular thin film is formed on the surface of the substrate, and in the second step, each of the first functional group of the molecular thin film or the third functional group obtained by converting the first functional group into another substituent, and an organic compound To form a functional organic thin film in which the main skeleton of the organic compound is periodically arranged on the molecular thin film.

According to another aspect, the present invention can provide a molecular thin film formed by the above-described manufacturing method and having a structure in which the same first functional group protrudes periodically on the surface of the substrate. By obtaining this molecular thin film, it is possible to easily form an organic thin film having various functionalities on the upper layer.
Furthermore, the present invention can further provide a functional organic thin film in which organic compounds are bonded and periodically arranged on the molecular thin film, and a substrate with various functionalities can be easily obtained. be able to.
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiment.

  According to the method for producing a functional organic thin film of the present invention, an organic material (organic compound) can be freely selected as long as it is a functional group that reacts with the protruding functional group of the molecular thin film. By selecting an appropriate organic material, functional organic thin films for various applications can be easily obtained. In addition, for example, by using a silane compound as a material for forming a molecular thin film, a functional organic thin film formed on a substrate can be obtained according to a network of molecular thin films in which silicon atoms and oxygen atoms are formed in a network structure. Since the upper organic compound is periodically arranged, a highly crystallized self-assembled monolayer can be constructed. Also, for example, if an organic material containing π-electron conjugated molecules is used, it has high conductivity in the direction perpendicular to the substrate surface, and the orbital overlap between molecules can be efficiently obtained in the plane direction. Since a functional organic thin film having a structure stacked by intermolecular interaction can be formed, excellent semiconductor characteristics exhibiting electrical anisotropy can be obtained. In other words, since the π-electron conjugated intermolecular distance at the top of the network is small, the conductivity in the direction perpendicular to the molecular plane due to hopping conduction is high, and the functionality has high conductivity in the molecular axis direction. As a conductive material, not only an organic thin film transistor material but also a solar cell, a fuel cell, a sensor and the like can be widely applied. In addition, since it is not necessary to synthesize and produce highly reactive organic materials as in the past, it is possible to use more versatile organic materials and to manufacture more versatile organic thin films. Since a vacuum process is not required, the manufacturing process can be simplified.

  In the present invention, the substrate can be appropriately selected depending on the use of the organic thin film. For example, elemental semiconductors such as silicon and germanium, semiconductors such as compound semiconductors such as GaAs, InGaAs, and ZnSe; so-called SOI substrates, multilayer SOI Substrate, SOS substrate, etc .; Glass, quartz glass; Insulator such as polymer film such as polyimide, PET, PEN, PES, Teflon (registered trademark); Stainless steel (SUS); Gold, platinum, silver, copper, aluminum, etc. High melting point metal such as titanium, tantalum, tungsten, etc .; Silicide with high melting point metal, polycide, etc .; Silicon oxide film (thermal oxide film, low temperature oxide film: LTO film, etc., high temperature oxide film: HTO film), silicon nitride Insulator such as film, SOG film, PSG film, BSG film, BPSG film; PZT, PLZT, ferroelectric, or antiferroelectric Electrical body: SiOF film, SiOC film or CF film, HSQ (hydrogen silsesquioxane) film (inorganic), MSQ (methyl silsesquioxane) film, PAE (polyarylene ether) film, BCB film formed by coating A low dielectric material such as a porous film, a CF film, or a porous film; Of these, a substrate capable of projecting active hydrogen such as a hydroxyl group and a carboxyl group to the surface or a substrate capable of projecting active hydrogen by a hydrophilization treatment is preferable. The hydrophilic treatment can be performed, for example, by immersing the substrate in a mixed solution of hydrogen peroxide and concentrated sulfuric acid.

In the present invention, it is important that the material for forming the molecular thin film used in the first step is a material capable of periodically protruding functional groups from the surface when the molecular thin film is formed. A compound can be mentioned. This silane compound had a part for forming a network structure film part (network) by silicon atoms and oxygen atoms as constituent atoms, and a part for reacting with an organic compound laminated as a second layer after the formation of the molecular thin film. Although it will not specifically limit if it is a silane compound, Especially, a functional group is made to project periodically from the network in which a silicon atom and an oxygen atom are formed in a network structure on the substrate in the first step. In view of this, it is preferable that the silicon atom has three functional groups for forming a network and one functional group (first functional group) for stacking in the second layer, for example, Examples thereof include trihalogenosilane having a first functional group, specifically vinyltrichlorosilane. Here, those having a vinyl group as the first functional group are listed, but other substituents such as amino group, carboxyl group, acyl group, formyl group, carbonyl group, nitro group, nitroso group, azide group, It may be an acid azide group or an acid chloride group.
Here, as the three functional groups for forming the network structure film portion composed of silicon atoms and oxygen atoms, any functional group may be used as long as it is a group that gives a hydroxyl group by hydrolysis. In addition to the halogen atom (Cl, F, Br, etc.) of trihalogenosilane, an alkoxy group having 1 to 4 carbon atoms is also exemplified.
Thus, by using a silane compound as a material for forming a molecular thin film, a functional organic thin film formed on a substrate has a structure according to a network of molecular thin films in which silicon atoms and oxygen atoms are formed in a network structure. Since the upper organic compound is periodically arranged, a highly crystallized self-assembled monolayer can be constructed.

  Thus, by using a silane compound as a material for forming the molecular thin film, the organic thin film formed on the surface of the base is formed in accordance with the network in which the silicon atoms and oxygen atoms of the lower molecular thin film are formed in a network structure. Since these organic compounds are periodically arranged, it is possible to construct a highly crystallized self-assembled monolayer.

The first functional group to be laminated with the second layer in the silane compound is any functional group that can react with the reaction site (second functional group) of the organic compound to be reacted as the second layer. For example, various functional groups such as amino group, carboxyl group, acyl group, formyl group, carbonyl group, nitro group, nitroso group, azide group, acid azide group, acid chloride group and the like can be mentioned.
Moreover, these 1st functional groups may be protected by the protective group arbitrarily. That is, these first functional groups are not limited to those capable of reacting with the substituent (second functional group) of the organic compound to be reacted in the second step. It may be capable of being converted into a third functional group capable of reacting with the organic compound to be reacted in the second step through several stages of processes (for example, including deprotection) between the two steps. . That is, in the production method of the present invention, the first functional group of the molecular thin film is converted into the third functional group capable of reacting with the second functional group of the organic compound between the first step and the second step. The process of converting may be included. Examples of this substituent conversion process include catalytic reaction, photoconversion reaction, etc. (for example, reduction from a nitro group to an amino group in the presence of a nickel catalyst) or deprotection by hydrolysis.

In the present invention, the organic compound to be reacted in the second step (organic compound for forming the second layer) is a functional group protruding from the molecular thin film formed in the first step (the first or third layer). Any compound may be used as long as it reacts with the functional group). However, in consideration of manufacturing an organic thin film having higher conductivity, a compound having a second functional group in which the main skeleton is constructed of π-electron conjugated molecules. In consideration of the yield and economic efficiency, the number of units constituting the π-electron conjugated system included in the π-electron conjugated molecule is within 30 and each unit is a linearly bonded compound. It is particularly preferred.
The functional thin film having such a π-electron conjugated molecule has high conductivity in the direction perpendicular to the substrate surface, and the molecular orbital overlap is efficiently obtained in the plane direction. Since a stacked structure can be formed by the interaction between the layers, it has excellent semiconductor characteristics that are electrically anisotropic. In other words, since the π-electron conjugated intermolecular distance at the top of the network is small, the conductivity in the direction perpendicular to the molecular plane due to hopping conduction is high, and the functionality has high conductivity in the molecular axis direction. As a conductive material, not only an organic thin film transistor material but also a solar cell, a fuel cell, a sensor and the like can be widely applied.

  The organic compound for forming the second layer is, for example, selected from the group consisting of aromatic hydrocarbons, condensed polycyclic hydrocarbons, monocyclic heterocyclic rings, condensed heterocyclic rings, alkenes, alkadienes, alkatrienes. Or a compound in which two or more of these compounds are bonded.

More specifically, as an organic compound for forming the second layer, the unit constituting the π-electron conjugated system contained in the π-electron conjugated molecule is an acene skeleton having 2 to 12 benzene rings. Can do.
Alternatively, as an organic compound for forming the second layer, a unit constituting a π-electron conjugated system included in the π-electron conjugated molecule is Si, Ge, Sn, P, Se, Te, Ti as a hetero atom. Or at least one unit of a monocyclic heterocyclic compound containing Zr, and further 1 to 9 units selected from a group derived from a monocyclic aromatic hydrocarbon and a monocyclic heterocyclic compound It can also be a π-electron conjugated organic residue.
Aromatic hydrocarbons include benzene, toluene, xylene, mesitylene, cumene, cymene, styrene, divinylbenzene and the like. Of these, benzene is preferred.
The condensed polycyclic hydrocarbon includes a hydrocarbon compound containing an acene skeleton (the following structural formula 1), a hydrocarbon compound containing an acenaphthene skeleton (the following structural formula 2), and a hydrocarbon compound containing a perylene skeleton (the following structural formula 3). , Indene, azulene, fluorene, acenaphthylene, biphenylene, pyrene, pentalene, phenalene and the like.

  Here, in the present invention, the acene skeleton is not limited to a hydrocarbon in which two or more benzene rings are linearly condensed, but is a hydrocarbon in which three or more benzene rings are condensed in a non-linear manner. Is also included. In the present invention, the linear hydrocarbon containing an acene skeleton has 2 to 12 benzene rings, and the number of benzene rings is 2 to 9 in consideration of the number of synthesis steps and product yield. Naphthalene, anthracene, naphthacene, pentacene, hexacene, heptacene, octacene and nonacene are particularly preferred. Examples of the non-linear hydrocarbon containing an acene skeleton include phenanthrene, chrysene, picene, pentaphen, hexaphen, heptaphene, benzoanthracene, dibenzophenanthrene, anthranaphthacene, and the like.

A specific method for synthesizing the acene skeleton of the formula (1) will be described below. These synthesis methods are merely examples, and other known synthesis methods can be applied.
Examples of the method for synthesizing an acene skeleton include (1) a method in which a hydrogen atom bonded to two carbon atoms at a predetermined position of a raw material compound is substituted with an ethynyl group, and then the ethynyl group is subjected to a ring-closing reaction to repeat the process, (2) Examples include a method in which a hydrogen atom bonded to a carbon atom at a predetermined position of the raw material compound is substituted with a triflate group, reacted with furan or a derivative thereof, and subsequently oxidized. An example of a method for synthesizing an acene skeleton using these methods is shown below.

Method (1)

Method (2)

  In the above method (2), since the benzene rings of the acene skeleton are increased one by one, for example, even if a predetermined part of the raw material compound contains a low-reactivity functional group or protective group, the organic silicon Compounds can be synthesized. An example of this case is shown below.

Ra and Rb are preferably a functional group having a low reactivity such as a hydrocarbon group or an ether group, or a protective group.
Further, in the reaction formula of the above method (2), the starting compound having two acetonitrile groups and a trimethylsilyl group may be changed to a compound in which these groups are all trimethylsilyl groups. In the above reaction formula, after the reaction using a furan derivative, the reaction product is refluxed under lithium iodide and DBU (1,8-diazabicyclo [5.4.0] undec-7-ene). A compound having one more benzene ring than the starting compound and two hydroxyl groups substituted can be obtained. Further, when the hydroxyl group of this compound is brominated by a known method and the bromo group is subjected to a Grignard reaction, a hydrophobic group can be introduced at the position of the bromo group. The acenaphthene skeleton and perylene skeleton can also be synthesized in accordance with the method for producing an acene skeleton in the above method (1). An example of the production method will be described below.

  In addition, as a method of inserting a secondary amino group in which a nitrogen atom is substituted with two aromatic ring groups as a side chain into a perylene skeleton, a metal catalyst is present after halogenating the insertion part of the side chain in advance. Below, a method of coupling the secondary amino group may be mentioned. For example, in the case of the perylene molecule, a secondary amino group can be inserted by the following method, for example.

The raw materials used in the above synthesis examples are general-purpose reagents that can be obtained and used from reagent manufacturers. For example, tetracene is available from Tokyo Kasei with a purity of 97% or more. Perylene can be obtained with a purity of 99% from Kishida Chemical, for example. The organosilicon compound thus obtained can be isolated and purified from the reaction solution by known means such as phase transfer, concentration, solvent extraction, fractional distillation, crystallization, recrystallization, chromatography and the like.
In the organosilicon compound of the present invention, since a hydrophobic group and a hydrophilic group (silyl group) are bonded to an acene skeleton, an acenaphthene skeleton or a perylene skeleton, a thin film of an organosilicon compound is formed on a hydrophilic substrate. The hydrophilic group of the substrate and the hydrophilic group of the compound are easily bonded, and the adsorptivity of the thin film to the substrate can be enhanced. That is, by increasing the lipophilicity or hydrophobicity of the portion other than the silyl group that is the reaction site between the organosilicon compound containing a π-electron conjugated molecule and the hydrophilic substrate, the effect of improving the reactivity with the substrate is achieved. Have. Furthermore, since it can also improve the solubility to the non-aqueous solution of an organosilicon compound by having a hydrophobic group, it can be easily applied to a solution process.

  As the monocyclic heterocycle, an S, N, O, Si, Ge, Se, Te, P, Sn, Ti or Zr atom is included as a heteroatom, and a 5-membered to 12-membered ring is preferable. Preferably, it is a 5-membered ring or a 6-membered ring. Examples of the compound containing an S, N or O atom as a hetero atom include oxygen atom-containing compounds such as furan, nitrogen atom-containing compounds such as pyrrole, pyridine, pyrimidine, pyrroline, imidazoline and pyrazoline, and sulfur such as thiophene. Atom-containing compounds, nitrogen and oxygen atom-containing compounds such as oxazole and isoxazole, sulfur and nitrogen atom-containing compounds such as thiazole and isothiazole, and the like, among which thiophene is particularly preferable. In addition, specific examples of compounds containing Si, Ge, Se, Te, P, Sn, Ti, or Zr atoms as heteroatoms include, for example, the following structural units as 5-membered ring units.

The 6-membered ring includes the following structural units.

These heterocyclic compound units have direct or indirect bonds between similar units or different units, and as a whole, 1 to 30 bonds form a π-electron conjugated organic residue. Furthermore, in consideration of yield, economy, and mass production, it is more preferable that 1 to 9 units are bonded. Furthermore, the heterocyclic compound unit may have a bond directly or indirectly with the unit of the aromatic hydrocarbon compound. The unit of the aromatic hydrocarbon compound is the same as the above condensed polycyclic hydrocarbon.
A plurality of these heterocyclic compound units may be bonded in a branched manner, but are preferably bonded linearly. Moreover, the same unit may couple | bond with the organic residue, all different units may couple | bond, and several types of units may couple | bond together in regular or random order. In addition, the position of the bond may be any of 2,5-position, 3,4-position, 2,3-position, 2,4-position, etc. when the constituent molecule of the unit is a 5-membered ring, Of these, the 2,5-position is preferred. When the monocyclic heterocyclic compound containing a Si, Ge, Se, Te, P, Sn, Ti, or Zr atom as a heteroatom is a 5-membered ring, in addition to the above, It does not matter. In the case of a 6-membered ring, any of 1,4-position, 1,2-position, 1,3-position and the like may be used, but among them, 1,4-position is preferable.
Furthermore, a vinylene group may be located between the heterocyclic compound units. Examples of hydrocarbons that give a vinylene group include alkenes, alkadienes, and alkatrienes. Alkenes include compounds having 2 to 4 carbon atoms, such as ethylene, propylene, butylene and the like. Of these, ethylene is preferable. Examples of the alkadiene include compounds having 4 to 6 carbon atoms, butadiene, pentadiene, hexadiene and the like. Examples of the alkatriene include compounds having 6 to 8 carbon atoms such as hexatriene, heptatriene, and octatriene.
From the above, examples of the π-electron conjugated molecule containing a monocyclic heterocyclic compound include the following compounds. R may be any functional group as long as it reacts with the functional group protruding from the molecular thin film formed in the first step.

Examples of the condensed heterocyclic ring include indole, isoindole, benzofuran, benzothiophene, indolizine, chromene, quinoline, isoquinoline, purine, indazole, quinazoline, cinnoline, quinoxaline, phthalazine and the like.
Alkenes include compounds having 2 to 4 carbon atoms, such as ethylene, propylene, butylene and the like. Of these, ethylene is preferable. Examples of the alkadiene include compounds having 4 to 6 carbon atoms, butadiene, pentadiene, hexadiene and the like.
Examples of the alkatriene include compounds having 6 to 8 carbon atoms such as hexatriene, heptatriene, and octatriene.
Among these compounds, a preferable organic compound having a π-electron conjugated molecule as a main skeleton is a compound in which 3 to 10 benzene rings or thiophene rings are linearly bonded.
Although the organic compound to be bonded in the second step has been described above, the organic compound used in the second step has a functional group that reacts with the first functional group protruding periodically on the surface of the substrate. Any of the above compounds may be laminated.

In the production method of the present invention, the reaction temperature of the first step, which is a reaction between the substrate and the first layer of the silane compound, and the second step of reacting the second layer on the molecular thin film formed on the substrate is: For example, it is -100-150 degreeC, Preferably it is -20-100 degreeC, and both reaction time is about 0.1 to 48 hours, for example. The reaction in the first and second steps is usually performed in an organic solvent that does not adversely influence the reaction. Examples of organic solvents that do not adversely affect the reaction include hydrocarbons such as hexane, pentane, benzene, and toluene, ether solvents such as diethyl ether, dipropyl ether, dioxane, and tetrahydrofuran (THF), and aromatic solvents such as benzene and toluene. Hydrocarbons etc. are mentioned, These can be used individually or as a liquid mixture. Of these, diethyl ether and THF are preferable. The reaction may optionally use a catalyst. As the catalyst, a known catalyst such as a platinum catalyst, a palladium catalyst, or a nickel catalyst can be used.
The second functional group contained in the organic compound reacted in the second step reacts with the protruding functional group (first or third functional group) of the molecular thin film formed on the substrate. If it is, it will not specifically limit, The various functional groups similar to the case of a molecular thin film can be selected.

  FIG. 1 is a schematic view showing a method for producing a functional organic thin film of the present invention at a molecular level, wherein FIG. 1 (a) shows a first step and FIG. 1 (b) shows a second step. FIG. 5C shows a functional organic thin film formed on the substrate.

  As shown in FIG. 1 (c), the present invention is a functional organic thin film 5 having a desired function on the surface of a desired substrate, for example, a substrate 1. It comprises a first-layer network structure film portion 3a bonded to the surface, and a second-layer organic film portion 4b periodically arranged on the surface of the network structure film portion 3a.

  In the method for producing a functional organic thin film of the present invention, first, as shown in FIG. 1A, in a first step, for example, a silane compound 2 is reacted with a substrate 1 (for example, quartz) by a chemical adsorption method. . After the reaction, as shown in FIG. 1B, the molecular thin film 3 having a self-organizing function in which silicon atoms and oxygen atoms are bonded to the surface of the substrate 1 in a network and the functional group R1 protrudes periodically. Is formed. Subsequently, in the second step, an organic compound having a functional group R2 capable of reacting with the functional group R1, for example, an organic compound 4 having a π-electron conjugated molecule 4a as a main skeleton is reacted by, for example, a chemical adsorption method. Thus, the organic compound 4 is chemically bonded onto the molecular thin film 3 having a network structure, and the π-electron conjugated molecules 4a are periodically formed on the network structure film portion 3a and the network structure film portion 3a described with reference to FIG. A functional organic thin film 5 composed of the organic film portions 4b arranged is formed.

  Below, the Example of the functional organic thin film of this invention and its manufacturing method is described.

[Example 1]: Formation of a molecular thin film using vinyltrichlorosilane, conversion to a carboxy-terminated molecular thin film, and formation of a functional organic thin film containing terthiophene using the molecular thin film Implementation of the production method of the present invention A method for producing a functional organic thin film containing terthiophene as Example 1 will be described with reference to FIG. FIG. 2 is a schematic diagram at the molecular level of each step of the functional organic thin film containing terthiophene. FIG. 2A shows the molecular thin film formed in the first step, and FIG. ) Shows a state in which the functional group of the molecular thin film is converted to another functional group, and FIG. 5C shows the functional organic thin film formed in the second step.

First, the quartz substrate 11 was immersed in a mixed solution of hydrogen peroxide and concentrated sulfuric acid (mixing ratio 3: 7) for 1 hour to hydrophilize the surface of the quartz substrate 11. Thereafter, the obtained substrate 11 is immersed in a 10 mM solution in which vinyltrichlorosilane is dissolved in a non-aqueous solvent (for example, n-hexadecane) for 5 minutes in an inert atmosphere, slowly pulled up, and solvent washing is performed. As shown in FIG. 2A, a network structure film portion 12a made of silicon atoms and oxygen atoms bonded on the quartz substrate 11 and a vinyl group periodically protruding from the surface of the network structure film portion 12a. A molecular thin film 12 was formed.
When the quartz substrate 11 on which the molecular thin film 12 was formed was measured with an infrared absorption spectrophotometer, absorption at a wavelength of 3090 cm ⁻¹ derived from C—H stretching vibration was obtained.

Subsequently, the obtained molecular thin film 12 is oxidized in the presence of potassium permanganate, for example, and then periodic acid is added, followed by solvent washing, whereby a network structure as shown in FIG. A molecular thin film 13 in which carboxyl groups periodically protrude from the surface of the film part 12a was formed.
When the quartz substrate 11 on which the molecular thin film 13 was formed was measured with an infrared absorption spectrophotometer, the absorption specific to the carboxyl group was obtained at a wavelength of 3450 to 3200 cm ⁻¹ derived from the carboxyl group. It was confirmed that the protruding functional group was converted from a vinyl group to a carboxyl group.

Furthermore, the molecular thin film 13 in which the vinyl group is converted to the carboxyl group as described above is immersed in a solution in which 10 mM aminoterthiophene is dissolved in a non-aqueous solvent (for example, toluene), and slowly pulled up and washed with a solvent. As shown in FIG. 2C, a terthiophene monomolecular film 14b, which is an organic film part, was formed on the network structure film part 12a to obtain a functional organic thin film 15.
When the quartz substrate 11 on which the functional organic thin film 15 was formed was measured with an ultraviolet-visible absorption spectrophotometer, 360 nm due to the absorption wavelength of terthiophene, which is a π-electron conjugated molecule, was detected. Moreover, the measurement result of 1.5 nm corresponding to the molecular length was obtained from the film thickness measurement by ellipsometry. This confirmed that a monomolecular film containing terthiophene, which is a π-electron conjugated molecule, was formed on the quartz substrate 11 via a network in which silicon atoms and oxygen atoms were formed in a network structure.

[Example 2]: Formation of a functional organic thin film containing terphenyl using a carboxy-terminated molecular thin film A molecular thin film 13 having a carboxyl group (see FIG. 2 (b)) produced by the same method as in Example 1, A terphenyl monomolecular film is formed on a molecular thin film by immersing it in a 10 mM solution in which terphenyltrichlorosilane is dissolved in a non-aqueous solvent (for example, n-hexadecane) for 2 hours, slowly pulling it up, and washing the solvent. A functional organic thin film was obtained.
When the quartz substrate on which this functional organic thin film was formed was measured with an ultraviolet-visible absorption spectrophotometer, 270 nm due to the absorption wavelength of terphenyl which is a π-electron conjugated molecule was detected. Moreover, a measurement result of 1.6 nm corresponding to the molecular length was obtained from the film thickness measurement by ellipsometry. Thereby, it was confirmed that a monomolecular film containing terphenyl which is a π-electron conjugated molecule was formed on a quartz substrate through a network in which silicon atoms and oxygen atoms were formed in a network structure.

[Example 3]: Conversion of a carboxy terminal molecular thin film into an amino terminal molecular thin film and formation of a functional organic thin film containing octadecane using the amino terminal molecular thin film A carboxyl group prepared by the same method as in Example 1 was used. The molecular thin film 13 (see FIG. 2B) was converted from a carboxyl group to an amino group by using acylation in SOCl ₂ and Hofmann decomposition reaction. The Hofmann decomposition reaction is a known synthesis technique for converting an amide group (R-CONH ₂ ) and an amino group by sequentially treating the compound having an acyl group with NH ₃ and OBr.

Subsequently, the molecular thin film having the amino group is immersed in a solution obtained by dissolving 10 mM stearic acid in a non-aqueous solvent (for example, toluene) for 2 hours, slowly pulled up, and then washed with a solvent. An octadecane monolayer was formed through an amide bond.
The quartz substrate with the this octadecane monomolecular film was subjected to measurement by infrared absorption spectrometer, the absorption derived from amide groups of wavelengths 1690 cm ^-1 and a wavelength 1540 cm ^-1 was confirmed. This indicates that an amide bond is contained in the film, and it was confirmed that stearic acid was bonded on the substrate. Further, in X-ray diffraction, a peak was confirmed at 2θ = 21.3 °, and it was found that a crystalline film having a plane spacing of 0.416 nm was formed.
As a result, it was confirmed that a monomolecular film containing octadecane was formed on the quartz substrate via a network in which silicon atoms and oxygen atoms were formed in a network structure.

[Example 4]: Formation of a functional organic thin film containing quarterphenyl using an amino-terminated molecular thin film, and measurement of electric conductivity in the film thickness direction of the functional organic thin film. The Si substrate provided with ~ 0.2Ω · cm) was immersed in a mixed solution of hydrogen oxide and concentrated sulfuric acid (mixing ratio 3: 7) for 1 hour to hydrophilize the substrate surface.

On this Si substrate, an ethoxytrichlorosilane molecular thin film is formed by the same method as in Example 3, and then a functional thin film containing quarterphenyl is formed by using 1-acyl quarterphenyl by the same method as in Example 2. Created.
As a result of measuring the electrical conductivity in the film thickness direction (perpendicular to the substrate) of the monomolecular film using an SPM (scanning probe microscope), a high value of 10 ⁻⁴ S / cm was obtained.

[Example 5]: Formation of a functional organic thin film containing quarterphenyl using an amino-terminated molecular thin film, and measurement of electric conductivity in the planar direction of the functional organic thin film Function containing quarterphenyl prepared in Example 4 A pair of electrode terminals was prepared on a quartz substrate having a conductive organic thin film by vapor deposition of Au. Thereafter, a DC power source for applying a predetermined voltage between both terminals and an ammeter conductivity measuring means for detecting a current between both terminals were provided.
When the electrical conductivity of the functional organic thin film containing quarterphenyl was measured, a value of 10 ⁻⁶ S / cm was obtained. Further, as a result of measuring the mobility by the TOF method (time of flight method), a value of 0.1 cm ² / V · s was shown. From these results, it became clear that this functional organic thin film has very excellent semiconductor characteristics in the planar direction (direction parallel to the film).

[Example 6]: Formation of functional organic thin film containing anthracene using carboxy-terminated molecular thin film A quartz substrate having a molecular thin film having a carboxyl group, prepared by the same method as in Example 1, was applied to 2 mM 1-aminoanthracene. A monomolecular film containing anthracene was formed on the molecular foil film by immersing it in the solution for 20 minutes, lifting it, and washing the solvent. The ultraviolet-visible absorption of the quartz substrate was 360 nm, which almost coincided with the anthracene absorption. Further, from the IR evaluation result of the quartz substrate, 1650 cm ⁻¹ NHCO-derived absorption was confirmed. This confirmed that an amide bond was formed. From the above, it was confirmed that an organic thin film containing anthracene was formed on a quartz substrate via a network of silicon atoms and oxygen atoms.

[Example 7]: Formation of functional organic thin film containing perylene using carboxy-terminated molecular thin film First, after reacting 1 mM perylene with a nitrating reagent (HNO ₃ / H ₂ SO ₄ ) to form nitroperylene, 1-Aminoperylene was synthesized by pressurization and reduction under H ₂ , Ni catalyst.
A quartz substrate having a carboxyl group-containing molecular thin film prepared by the same method as in Example 1 was immersed in 5 mM of the 1-aminoperylene solution for 30 minutes, pulled up, and then washed with a solvent to obtain a molecular foil film. A monomolecular film containing perylene was formed. The ultraviolet-visible absorption of the quartz substrate including the organic thin film was 380 nm, which almost coincided with the absorption of perylene. Further, absorption from NHCO at 1630 cm ⁻¹ was confirmed from the IR evaluation result of the quartz substrate. This confirmed that an amide bond was formed. From the above, it was confirmed that an organic thin film containing perylene was formed on a quartz substrate via a network of silicon atoms and oxygen atoms.

[Example 8]: Formation of functional organic thin film containing diselenophene using carboxy-terminated molecular thin film Diselenophene can be synthesized based on the production method described in Polymer, 2003, 44, 5597-5603. . Furthermore, after reacting selenophene with a nitrating reagent (HNO ₃ / H ₂ SO ₄ ) to form nitrodiselenophene, 1-aminodiselenophene is synthesized by pressurizing and reducing under H ₂ , Ni catalyst. did. Subsequently, a quartz substrate having a molecular thin film having a carboxyl group prepared by the same method as in Example 1 was immersed in 5 mM of the 2-aminodiselenophene solution for 2 hours, and then pulled up and washed with a solvent. A monomolecular film containing diselenophene was formed on the molecular thin film. From the IR evaluation results of the quartz substrate, 1670 cm ⁻¹ NHCO-derived absorption was confirmed. This confirmed that an amide bond was formed. Moreover, when the film thickness was evaluated by ellipsometry before and after the diselenophenetrichlorosilane reaction, the difference in film thickness before and after was 0.9 nm. This corresponds to the molecular length of diselenophene. From the above, it was confirmed that an organic thin film containing diselenophene was formed on a quartz substrate via a network of silicon atoms and oxygen atoms.

  The functional organic thin film of the present invention can be widely applied not only to organic thin film transistor materials but also to solar cells, fuel cells, sensors and the like as conductive materials.

It is the schematic diagram which showed the manufacturing method of the functional organic thin film of this invention in the molecular level. 2 is a schematic diagram of a molecular level in each step of a functional organic thin film containing terthiophene in Example 1. FIG. It is a figure for demonstrating the relationship between intermolecular distance and intermolecular force.

Explanation of symbols

1,11 Base (substrate)
2 Silane compound 3, 12 Molecular thin film 3a, 12a Network structure film part 4 Organic compound 4a π electron conjugated molecule 4b Organic film part 5, 14 Functional organic thin film 14b Organic film part (terthiophene monomolecular film)

Claims (12)

A first step of forming a molecular thin film in which a first functional group protrudes periodically on a surface of a substrate;
The second functional group of the organic compound is reacted with the first functional group of the molecular thin film or the third functional group obtained by converting the first functional group, and the organic compound is bonded onto the molecular thin film to cause periodicity. And a second step of forming an organic thin film that is arranged on the substrate. A method for producing a functional organic thin film. The material for forming the molecular thin film used in the first step is a silane compound having a first functional group,
In the first step, a network structure film portion formed by silicon atoms and oxygen atoms which are constituent atoms of the silane compound is bonded to the surface of the substrate, and the first functional group is bonded from the network structure film portion. The method for producing a functional organic thin film according to claim 1, wherein the molecular thin film is formed protruding periodically.   The method of converting the 1st functional group of a molecular thin film into the 3rd functional group which can react with the 2nd functional group of an organic compound between a 1st process and a 2nd process. 2. A method for producing a functional thin film according to 2.   The method for producing a functional thin film according to claim 3, wherein the organic compound used in the second step is a compound having a second functional group whose main skeleton is constructed by a π-electron conjugated molecule.   5. The organic compound is a compound in which the number of units constituting the π-electron conjugated system contained in the π-electron conjugated system molecule is within 30 and each unit is bonded linearly. A method for producing a functional organic thin film.   In organic compounds, the units constituting the π-electron conjugated system contained in the π-electron conjugated molecule are aromatic hydrocarbons, condensed polycyclic hydrocarbons, monocyclic heterocyclic rings, condensed heterocyclic rings, alkenes, alkadienes, 6. The method for producing a functional organic thin film according to claim 4, wherein the functional organic thin film is one or more compounds selected from the group consisting of trienes.   The functional group according to any one of claims 4 to 6, wherein the organic compound is a unit comprising a benzene ring having 2 to 12 acene skeletons in a π electron conjugated system contained in the π electron conjugated system molecule. Organic thin film manufacturing method.   An organic compound is a monocyclic heterocyclic compound in which a unit constituting a π-electron conjugated system included in the π-electron conjugated molecule includes Si, Ge, Sn, P, Se, Te, Ti, or Zr as a hetero atom. A π-electron conjugated organic residue in which 1 to 9 units selected from a group derived from a monocyclic aromatic hydrocarbon and a monocyclic heterocyclic compound are bonded. The method for producing a functional organic thin film according to any one of claims 4 to 6.   The method for producing a functional organic thin film according to claim 8, wherein the organic compound is composed of benzene, thiophene or ethylene as a unit constituting the π-electron conjugated system contained in the π-electron conjugated molecule. Prior to the first step, the surface of the substrate is hydrophilized,
Thereafter, in the first step, the hydrophilically treated substrate is immersed in a solution in which vinyltrihalogenosilane is dissolved in a non-aqueous solvent, the network structure film portion is bonded to the surface of the substrate, and the network structure film A molecular thin film in which vinyl groups protrude periodically from the surface of the part,
Before the second step, the obtained molecular thin film is oxidized to convert the vinyl group into a carboxyl group,
In the third step, the substrate on which the molecular thin film having a carboxyl group is formed is immersed in a solution in which aminoterthiophene is dissolved in a non-aqueous solvent, and a terthiophene monomolecular film is formed on the network structure film portion. The method for producing a functional organic thin film according to any one of claims 3 to 9, wherein a functional organic thin film is obtained.   A molecular thin film formed by the method for producing a functional organic thin film according to claim 1, 2 or 10, and having a structure in which a first functional group protrudes periodically on a surface of a substrate.   The functional organic thin film which the organic compound couple | bonds with the molecular thin film formed with the manufacturing method of the functional organic thin film as described in any one of Claims 1-10, and arranges periodically.

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