JPH0620123B2 - Porous organic semiconductor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a porous organic semiconductor. More specifically, it relates to a porous organic semiconductor which is a heat-treated product of an aromatic condensation polymer which is a condensation product of an aromatic hydrocarbon compound having a phenolic hydroxyl group and an aldehyde.

[Conventional technology]

Polymer materials are excellent in moldability, light weight and mass productivity. Therefore, by utilizing these characteristics of the polymer material, an organic polymer material having electrical semiconductivity is desired in many industrial fields including the electronics industry. The early organic semiconductors were difficult to be formed into a film-like or plate-like body, and did not have the property as an n-type or p-type impurity semiconductor, so that they were limited in use.

In recent years, it has become possible to obtain organic semiconductors having relatively excellent moldability, and moreover, to obtain an n-type or p-type organic semiconductor by doping these semiconductors with an electron-donating dopant or an electron-accepting dopant. Is possible. Polyacetylene is a typical example of such an organic semiconductor. This organic semiconductor is about ^10-5 (Ω-c
m) ^{-1 has} an electric conductivity, but the electric conductivity is greatly increased by doping an electron accepting dopant such as I ₂ or AsF ₅ or an electron donating dopant such as Li or Na. Can be improved, and 10 ² to 10 ³ (Ω−
A conductivity of cm) ^-1 is obtained. However, polyacetylene has a drawback that it is easily oxidized by oxygen. Therefore, it is difficult to handle in air, and it is not practical as an industrial material.

Further, Japanese Patent Application Laid-Open No. 58-1 filed by the same applicant as the present application
36,649 discloses a heat-treated product of (A) an aromatic condensation polymer composed of carbon, hydrogen and oxygen, wherein the atomic ratio of hydrogen atoms / carbon atoms is 0.60 to 0.15. An insoluble and infusible substrate containing a structure, and (B)
Disclosed is (C) an electrically conductive organic polymer material which is composed of an electron donating doping agent or an electron accepting doping agent and has a higher electrical conductivity than the undoped substrate. The insoluble and infusible substrate is excellent in heat resistance and oxidation resistance, and can be doped with an electron donating doping agent or an electron accepting doping agent as described above, and has p-type or n-type properties. The organic semiconductor shown is given. However, the above-mentioned publication does not describe a porous substrate or a porous organic semiconductor.

On the other hand, a ceramic porous body or a carbon porous body is known as a porous body having continuous ventilation holes having excellent heat resistance and chemical resistance, and is used in many industrial fields including materials.

However, a porous organic semiconductor having excellent heat resistance and chemical resistance has not yet been developed in spite of great social needs in today's high technology era.

[Problems to be solved by the invention]

An object of the present invention is to provide a porous organic semiconductor.

Another object of the present invention is to provide a porous organic semiconductor having excellent heat resistance and oxidation resistance.

It is still another object of the present invention to provide an organic semiconductor having a large number of through holes that can be rapidly and uniformly doped with an electron accepting dopant and / or an electron donating dopant.

Still another object of the present invention is to provide an electron-accepting dopant and / or an organic semiconductor doped with an electron-accepting dopant.

Still another object of the present invention is to provide a porous organic semiconductor in the form of a film, a plate or the like.

Still another object of the present invention is to provide an organic semiconductor having fine communication holes, which easily causes various chemical reactions or physical adsorption.

Further objects and advantages of the present invention will be apparent from the following description.

[Means and Actions for Solving Problems]

According to the present invention, the above objects and advantages of the present invention are: a heat-treated product of an aromatic condensation polymer, which is a condensation product of an aromatic hydrocarbon compound having a phenolic hydroxyl group and an aldehyde, wherein (a) hydrogen Atom / carbon atom atomic ratio is 0.6 to 0.05
Which has a polyacene-based skeleton structure, and (b) has communicating pores with an average pore diameter of 10 μm or less, and (c) exhibits a three-dimensional network structure through a large number of communicating pores. Is achieved by

The aromatic condensation polymer in the present invention is a condensation product of an aromatic hydrocarbon compound having a phenolic hydroxyl group and an aldehyde. As such an aromatic hydrocarbon compound, so-called phenols such as phenol, cresol, and xylenol are suitable, but not limited thereto. For example, the following formula Here, x and y are each independently 0, 1 or 2 and may be a methylene-bisphenol compound represented by: or a hydroxy-biphenyl compound or a hydroxynaphthalene compound. Of these, phenols are particularly suitable for practical use.

The aromatic condensation polymer in the present invention further includes 1 of aromatic hydrocarbon compounds having a phenolic hydroxyl group.
It is also possible to use a modified aromatic polymer in which a portion is substituted with an aromatic hydrocarbon compound having no phenolic hydroxyl group, such as xylene or toluene, for example, a modified aromatic polymer which is a condensate of phenol, xylene and formaldehyde.

Also, not only formaldehyde as aldehyde,
Formaldehyde is preferred, although other aldehydes such as acetaldehyde, furfural can also be used. The phenol / formaldehyde condensate may be a novolak type, a resol type, or a complex thereof.

The porous organic semiconductor of the present invention is a heat-treated product of the aromatic condensation polymer as described above and can be produced, for example, as follows.

Preparing an initial condensation product of an aromatic hydrocarbon compound having a phenolic hydroxyl group or an aromatic hydrocarbon compound having a phenolic hydroxyl group and an aromatic hydrocarbon compound not having a phenolic hydroxyl group and an aldehyde, and the initial condensation product An aqueous solution containing an inorganic salt is prepared, and the aqueous solution is poured into a suitable mold, and then the aqueous solution is heated while suppressing evaporation of water to form a plate-shaped, film-shaped, or cylindrical shape in the mold. After curing and conversion, the cured body is washed to remove the inorganic salts contained in the cured body, and the resulting porous cured condensate is then heated in a non-oxidizing atmosphere at 400
Heat to a temperature of up to 800 ° C.

The above-mentioned inorganic salt used together with the initial condensate is a pore-forming agent which is removed in a later step and is used for imparting communicating pores to the cured body, and examples thereof include zinc chloride, sodium phosphate, potassium hydroxide or potassium sulfide. . Of these, zinc chloride is particularly preferably used. The inorganic salt can be used in an amount of, for example, 2.5 to 10 times the initial condensation product. If the amount is less than the lower limit, it is difficult to obtain a porous cured product having communicating pores, and if the amount is more than the upper limit, the mechanical strength of the finally obtained heat-treated product tends to decrease, which is not desirable. The aqueous solution of the initial condensate and the inorganic salt varies depending on the type of the inorganic salt used, but can be prepared using, for example, 0.1 to 1 times the weight of water of the inorganic salt. Thus, an aqueous solution having a viscosity of, for example, 100,000 to 100 centipoise is poured into a suitable mold, for example 50 to 200.
It is heated to a temperature of ° C. At the time of this heating, it is important to suppress evaporation of water in the aqueous solution. That is, it is considered that the initial condensate is gradually hardened by being heated in the aqueous solution and grows into a three-dimensional network structure while being separated from zinc chloride and water.

By thoroughly washing the obtained cured product with water, diluted hydrochloric acid or the like, the inorganic salt contained in the cured product can be removed. When the inorganic salt is removed and then dried, a porous cured condensate having developed communication pores can be obtained.

The thus obtained porous cured condensate is then heated to a temperature of 400 to 800 ° C., preferably 450 to 750 ° C., particularly preferably 500 to 700 ° C. in a non-oxidizing atmosphere (including a vacuum state). Heated and heat treated.

The preferable heating rate during the heat treatment is somewhat different depending on the aromatic condensation polymer used, the degree of the curing treatment or the shape thereof, etc., but generally the temperature rises relatively from room temperature to about 300 ° C. It can be a temperature rate, for example, a rate of 100 ° C./hour. At a temperature of 300 ° C. or higher, thermal decomposition of the aromatic condensation polymer starts, and gases such as steam (H ₂ O), hydrogen, methane, and carbon monoxide start to be generated, so that the temperature rises at a sufficiently slow rate. It is advantageous to heat.

Such heating and heat treatment of the aromatic condensation polymer are performed in a non-oxidizing atmosphere. The non-oxidizing atmosphere is, for example, nitrogen, argon, helium, neon, carbon dioxide or the like, and nitrogen is preferably used. The non-oxidizing atmosphere may be stationary or flowing.

Thus, by the above heating and heat treatment, the atomic ratio of hydrogen atoms / carbon atoms (hereinafter referred to as H / C ratio) is 0.6 to 0.0.
The porous organic semiconductor of the present invention has a polyacene skeleton structure of 5, preferably 0.5 to 0.15, and has communicating pores with an average pore diameter of 10 μm or less, for example, communicating pores with an average pore diameter of 0.03 to 10 μm. can get. The porous organic semiconductor of the present invention is insoluble and infusible. The atomic ratio of oxygen atoms / carbon atoms (O / C ratio) is usually 0.06 or less, preferably 0.
It is 03 or less. Further, according to X-ray diffraction (CuO _α ), the position of the main peak is represented by 2θ and ranges from 20.5 to
It exists between 23.5 ° and another broad peak between 41 and 46 ° in addition to the main peak.
According to the infrared absorption spectrum, D (= D ₂₉₀₀ ~
The absorbance ratio of ₂₉₄₀ / D ₁₅₆₀ to ₁₆₄₀ ) is usually 0.5 or less, preferably 0.3 or less.

That is, it is understood that the insoluble and infusible substrate has a polyacene-based benzene polycyclic structure uniformly and moderately developed among polyacene-based molecules.

According to the present invention, there is also provided a porous organic semiconductor obtained by doping the insoluble and infusible substrate with an electron donating dopant, an electron accepting dopant, or both of these dopants.

That is, according to the present invention, (A) a heat-treated product of an aromatic condensation polymer, which is a condensation product of an aromatic hydrocarbon compound having a phenolic hydroxyl group and an aldehyde, (a) hydrogen atom / carbon atom Has a polyacene skeleton structure with an atomic ratio of 0.6 to 0.05 and (b) has communicating pores with an average pore diameter of 10 μm or less, and (c) is a porous insoluble insoluble material having a three-dimensional network structure through a large number of communicating pores. A porous organic semiconductor comprising a fusible substrate and (B) an electron donor dopant and / or an electron accepting dopant.

As the electron donating dopant, a substance that easily releases electrons is used. For example, a Group 1A metal of the periodic table such as lithium, sodium, potassium, rubidium or cesium is preferably used.

Similarly, as the electron donating dopant, tetra (C ₁
-C ₄ alkyl) ammonium cation example (CH _3)
4 N ⁺ or (C ₄ H ₉ ) ₄ N ⁺ can be used.

A substance that easily accepts electrons is used as the electron-accepting dopant. For example, halogen such as fluorine, chlorine, bromine, iodine; AsF ₅ , PF ₅ , BF ₃ , BCl ₃ , B
Halogen compounds such as Br ₃ and FeCl ₃ ; Oxides of non-metal elements such as SO ₃ or N ₂ O ₅ ; or H ₂ S
Anions derived from an inorganic acid such as O ₄ , HNO ₃ or HClO ₄ are preferably used.

As the doping method of such a dopant, essentially the same doping method as that conventionally used for polyacetylene or polyphenylene can be used.

For example, when the dopant is an alkali metal, it can be doped by bringing molten alkali metal or vapor of alkali metal into contact with an insoluble infusible substrate, and is insoluble in an alkali metal naphthalene complex produced in tetrahydrofuran, for example. It can also be doped by contacting it with an infusible substrate.

When the dopant is halogen, a halogen compound or an oxide of a non-metal element, the doping can be easily performed by bringing these gases into contact with the insoluble and infusible substrate.

When the doping agent is an anion derived from an inorganic acid, it can be carried out by directly coating or impregnating the insoluble and infusible substrate with the inorganic acid.

It is also possible to electrochemically dope an electron donating dopant such as lithium or sodium or an electron accepting dopant such as ClO ₄ ⁻ or BF ₄ ⁻ by setting an insoluble and infusible substrate as an electrode.

As described above, since the insoluble and infusible substrate of the present invention is a porous body having communicating holes, it facilitates the diffusion of the gaseous dopant or the dopant in the solution as described above, and enables rapid and uniform doping. Has excellent advantages.

The doping agent is generally used in a ratio of 10 ⁻⁵ mol or more based on the repeating unit of the aromatic condensation polymer so as to be present in the obtained organic semiconductor of the present invention.

The organic semiconductor of the present invention thus obtained has an electric conductivity (for example, 10 ⁻¹² to 10 ²⁾ of the insoluble and infusible substrate before doping.
The electric conductivity is higher than Ω ⁻¹ · cm ⁻¹ ), for example, several times to 10 ¹⁰ times higher than that of the insoluble and infusible substrate before doping. When doped with an electron donating dopant, it gives an n-type semiconductor, and when doped with an electron accepting dopant, it gives a p-type semiconductor. According to the present invention, an electron donating dopant and an electron accepting dopant can be used together as a dopant. When these dopants are mixed almost uniformly in the porous organic semiconductor of the present invention, either one of the dopants, which is more abundant, becomes p-type or n-type. For example, when there are many electron-donating dopants, it becomes n-type, and when there are many electron-accepting dopants, it becomes p-type.

[Operation and effect of invention]

The porous organic semiconductor of the present invention is excellent in heat resistance and oxidation resistance, and can be formed into any shape such as a film shape, a plate shape, or a cylindrical shape, and thus is a highly practical material.

In the porous organic semiconductor of the present invention, the insoluble and infusible substrate having a polyacene-based skeleton structure has a three-dimensional network structure through the communication holes, so that the fluid can easily flow in and out through the communication holes in detail. . The average pore diameter of the communicating pores is as fine as 10 μm or less, and the pore body has a uniform pore diameter, that is, a sharp pore size distribution. In addition, since it is possible to obtain from a very fine porous body having an average pore size of 0.1 μm to a porous body having an average pore size of about 10 μm, it is possible to properly use the porous body depending on the application.

Utilizing the fine communication holes of the porous organic semiconductor of the present invention,
Various chemical reactions that occur at the interface can be rapidly promoted, and are suitably used, for example, as an electrode material for batteries. In addition, various physical adsorptions occur smoothly and uniformly, so that the adsorption of gas such as H ₂ O and O ₂ causes a slight change in electrical conductivity in combination with the properties as a semiconductor.
Therefore, the apparent density of the porous organic semiconductor of the present invention, which can be suitably used as a sensor material, is usually 0.3.
Is a ~0.8g / cm ^3. In other words, porous materials having a high porosity to porous materials having a relatively low porosity are included in the porous organic semiconductor of the present invention. The mechanical strength of the porous body varies depending on the apparent density, but even the porous body of the present invention of 0.3 g / cm ³ has a sufficient strength for practical use. Further, since the porous organic semiconductor of the present invention is composed of an insoluble and infusible substrate having a polyacene-based skeleton structure, it has excellent chemical resistance and also has fine ventilation holes, so that it can be used under severe conditions. It is also suitable as a material to be used.

As described above, the porous organic semiconductor of the present invention is excellent in heat resistance and oxidation resistance, and has fine open pores, so that the organic acceptor or electron donating dopant can be rapidly and uniformly doped. In addition, since it can take an arbitrary shape such as a film shape or a plate shape having excellent mechanical strength, it is an industrially useful material that can be applied to various fields.

In addition, in the present specification, the average pore diameter of the communicating holes is measured and defined as follows.

An electron micrograph of the sample is taken at a magnification of 1000 to 10,000, for example. Draw an arbitrary straight line on this photo,
The average pore diameter () is calculated by the following equation, where n is the number of pores intersecting the straight line.

Here, li is a length cut by a hole where straight lines intersect, Is the sum of the cut lengths for n holes, and n
Is the number of holes intersecting the straight line, where n is a value of 10 or more.

This will be described in detail below with reference to examples.

Example 1 (1) An aqueous solution prepared by mixing water-soluble resol (about 60% concentration) / zinc chloride / water at a weight ratio of 10/25/4 was formed on a glass plate with a film applicator. Next, a glass plate was covered on the aqueous solution thus formed to prevent moisture from evaporating, and heated at a temperature of about 100 ° C. for 1 hour to be cured.
The obtained cured film was washed with dilute hydrochloric acid, washed with water and then dried to obtain a film-like cured phenol resin resin having a thickness of about 200 μm.

The phenol resin-cured porous body was placed in a silicon nitride electrification furnace and heated in a nitrogen stream at a rate of 40 ° C./hour to 60
Heat treatment was performed up to 0 ° C. to obtain an insoluble and infusible film-like porous body. When the electric conductivity of the porous body was measured by the DC 4-terminal method, it was 10 ⁻⁷ (Ωcm) ⁻¹ . The apparent density was 0.40 g / cm ³ , and the film was excellent in mechanical strength. Further, elemental analysis of the film revealed that the atomic ratio of hydrogen atoms / carbon atoms was 0.34. The shape of the peak obtained from X-ray diffraction is a pattern based on the polyacene skeleton structure, and is 20 at 2θ.
A broad main peak was present around -24 °, and a small peak was confirmed around 41-46 °.

Next, in order to observe the pore state of the film-shaped semiconductor, an electron micrograph of the film cross section was taken. It is shown in FIG. As is clear from FIG. 1, the three-dimensional mesh structure,
It was a porous body having fine open pores of 10 μm or less.

(2) Next, a tetrahydrofuran solution of sodium naphthalate was prepared using dehydrated tetrahydrofuran, naphthalene and metallic sodium. The above film-shaped semiconductor was immersed in this solution in a dry box, and was doped at room temperature for about 1 hour. After washing with dehydrated tetrahydrofuran, it was dried under reduced pressure for about 10 hours. The electrical conductivity of the dried sample is about 10 ^-1 (Ω · cm)
^{It was -1} .

Examples 2 to 5 (1) A film-like phenol resin cured porous body having a thickness of about 200 μm obtained in the same manner as in Example 1 was heated at a rate of about 30 ° C./hour under a nitrogen stream in a silicone electric furnace. First
Heat treatment was carried out by heating to various predetermined temperatures shown in the table. Elemental analysis of the obtained porous semiconductor film,
The electrical conductivity was measured. The results are shown in Table 1.

(2) Next, these semiconductor films were put into a vacuum line, the degree of vacuum was adjusted to about 10 ^-2 Torr, and then iodine gas was introduced into the line at room temperature to perform doping for about 10 minutes. The electric conductivity at this time is shown in Table 1.

When the distribution state of iodine was examined by EPMA (Electron Micron Analyzer) on the cross section of the film sample doped with iodine, it was found that the iodine was uniformly distributed.

The electrical conductivity was greatly increased by the iodine doping.

[Brief description of drawings]

FIG. 1 is an electron micrograph of the particle structure (porous structure) of the cross section of the porous organic semiconductor film of the present invention. In the photograph, the length of the bar line shown in the lower right is 5μ.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-57-207329 (JP, A) JP-A-58-69234 (JP, A)

Claims (13)

[Claims] 1. A heat-treated product of an aromatic condensation polymer which is a condensation product of an aromatic hydrocarbon compound having a phenolic hydroxyl group and an aldehyde, wherein (a) the atomic ratio of hydrogen atom / carbon atom is 0. 6-0.0
No. 5, which has a polyacene skeleton structure, (b) has communicating pores with an average pore diameter of 10 μm or less, and (c) has a three-dimensional network structure through a large number of communicating pores. semiconductor. 2. The porous organic semiconductor according to claim 1, wherein the aromatic condensation polymer is a condensation product of phenol and formaldehyde. 3. An atomic ratio of hydrogen atoms / carbon atoms of 0.5 to.
The porous organic semiconductor according to claim 1, which is 0.15. 4. The porous organic semiconductor according to claim 1, which has a large number of communicating holes having an average pore diameter of 0.03 to 10 μm. 5. A polyacene skeleton structure having an atomic ratio of oxygen atom (O) / carbon atom (C) of 0.06 or less,
The porous organic semiconductor according to claim 1. 6. The porous organic semiconductor according to claim 1, which is a film, a plate, a fiber or a composite thereof. 7. A heat-treated product of (A) an aromatic condensation polymer which is a condensation product of an aromatic hydrocarbon compound having a phenolic hydroxyl group and an aldehyde, wherein (a) hydrogen atom /
It has a polyacene skeleton structure in which the atomic ratio of carbon atoms is 0.6 to 0.05, (b) has communicating holes with an average pore diameter of 10 μm or less, and (c) has a three-dimensional network structure through a large number of communicating holes. And a porous organic semiconductor, comprising (B) an electron donor dopant and / or an electron accepting dopant. 8. The invention according to claim 7, which exhibits electric conductivity higher than that of the porous insoluble and infusible substrate (A).
The porous organic semiconductor according to item. 9. A first A wherein the electron donating dopant comprises lithium, sodium, potassium, rubidium and cesium.
The porous organic semiconductor according to claim 7, which is a group metal. 10. The electron donating dopant is tetra (C _1- ).
The porous organic semiconductor according to claim 7, which is a C ₅ lower alkyl) ammonium cation. 11. An electron-accepting dopant is AsF ₅ , P.
The porous organic semiconductor according to claim 7, which is a halide such as F ₅ , BF ₃ , BCl ₃ , BBr ₃ , or FeCl ₃ . 12. The electron-accepting dopant is fluorine, chlorine,
Claim 7 which is halogen such as bromine and iodine.
The porous organic semiconductor according to item. 13. The electron-accepting dopant is an oxide of a non-metal element such as SO ₃ or N ₂ O ₅ , or H ₂ SO ₄ , HNO.
The porous organic semiconductor according to claim 7, which is an anion derived from an inorganic acid such as ₃ or HClO ₄ .