JPH05339379A - Production of organic conductive material - Google Patents

Abstract

PURPOSE:To obtain the title material improved in conductivity and excellent in mechanical strength and chemical resistance by the joint vapor deposition or plasma polymerization of an electron acceptor and an electron donor. CONSTITUTION:The title material is obtained by the joint vapor deposition or plasma polymerization of an-electron acceptor of formula I [wherein R1 is a group of formula IV or 0-(a group of formula IV) (wherein m is 0 to 12), or F; and R<2> is a group of formula V or 0-(a group of formula V) (wherein n is 0 to 12), or F] and an electron donor of formula 11 [wherein X is S, Se or Te; R<3> is a group of formula VI or Y<1>-(a group of formula VI) (wherein j is 0 to 12; and Y<1> is 0, S, Se or Te); and R<4> is a group of formula VII or Y<2>-(a group of formula VII) (wherein k is 0 to 12; and Y<2> is O, S, Se or Te)] or formula III (wherein X is S, Se or Te).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an organic conductive material suitable for use as an electronic material such as an electrode of a secondary battery or a switch of a transistor.

[0002]

2. Description of the Related Art Recently, as a conductive material along with metal,
The development of organic conductive materials made of polymer compounds has been actively pursued. The most famous polymer compound as the organic conductive material is polyacetylene, and other compounds having aromatic rings or heterocycles such as polypyrrole, polythiophene, and polyaniline have long been known.

As a method for producing these polymer compounds,
For example, Japanese Patent Publication No. 48-32581 and Japanese Patent Laid-Open No. 58-8.
7147, JP-B-58-24446, JP-A-57-133127, JP-A-61-19631.
As disclosed in Japanese Unexamined Patent Publication (KOKAI) Publication, various methods such as firing method, electrolytic polymerization method, chemical polymerization method, plasma polymerization method and the like have been studied.

However, the conductivity of each of these polymer compounds is limited to the range of 10 ^-3 S / cm or less, and it is difficult to set the conductivity to 10 ⁰ S / cm or more even when impurities are doped. is there. In particular, when a polymer compound is produced by an electrolytic polymerization method, a conductive coating film is deposited on an electrode, but the surface of the obtained coating film is uneven and mechanical strength is generally low.

Among the above organic conductive materials, for example, tetrathiafulvalene (hereinafter abbreviated as TTF) and 7,7,8,8-tetracyanoquinodimethane (hereinafter T).
Abbreviated as CNQ. ) Synthesized from TTF-TCNQ
Is known to use TTF and TCNQ as electron acceptors or electron donors, respectively, to form a charge transfer complex between molecules.

In the charge transfer complex represented by TTF-TCNQ, an electric conductivity of about 10 ⁰ S / cm has been conventionally obtained. This charge-transfer complex is conventionally produced by vapor deposition using a chemically synthesized complex as a starting material, but the charge-transfer complex formed by such a method is not polymerized. Has low mechanical strength and chemical resistance, and has problems in terms of moldability.

On the other hand, for example, benzene, 3, 4,
9,10-perylene tetracarboxylic acid diimide derivative,
Regarding compounds such as thiophene and pyrrole, it has been reported that a polymerized film can be obtained by low-temperature plasma [for example, JP-A-1-165603 and JP-A-2-238].
026, etc., or Polym. Preprint vol.31-10p27
51 (1982) See Suzuki et al. ].

[0008]

Therefore, the present invention has been proposed in view of the above-mentioned circumstances, and is the TTF-TC.
It is an object of the present invention to provide a method for producing an organic conductive material capable of improving the conductivity of a charge transfer complex represented by NQ and obtaining excellent mechanical strength and chemical resistance.

[0009]

As a result of earnest research, the present invention, etc. will not become an electron acceptor.
By using a TF compound and a TCNQ compound as an electron donor as starting materials and sublimating two compounds at the same time in the vapor phase to form a film directly on the substrate, a good charge transfer complex thin film can be obtained. It was found that the present invention has been completed.

That is, the first invention of the present application is characterized by co-evaporating an electron acceptor represented by the following Chemical formula 7 and an electron donor represented by the following Chemical formula 8 or Chemical formula 9. ..

[0011]

[Chemical 7]

[0012]

[Chemical 8]

[0013]

[Chemical 9]

The second invention of the present application is as follows.
And an electron donor represented by the following chemical formula 11 or 12 is plasma-polymerized.

[0015]

[Chemical 10]

[0016]

[Chemical 11]

[0017]

[Chemical formula 12]

The above-mentioned electron acceptor TCNQ (7, 7,
The 8,8-tetracyanoquinodimethane) -based compound is represented by the above formula (1) and is a TT that serves as an electron donor.
The F (tetrathiafulvalene) -based compound has the above (2) to
It is represented by the equation (3). A charge transfer complex is formed between the molecules of the TCNQ compound and the TTF compound.

As a method for synthesizing this charge transfer complex,
In the first invention of the present application, a so-called co-evaporation method is used, and in the second invention of the present application, plasma polymerization is used.

First, in the first invention of the present application, the TCNQ-based compound and the TTF-based compound are simultaneously sublimated to perform co-evaporation to form a conductive film on the substrate. This makes it possible to obtain a charge transfer complex thin film having a conductivity that is nearly two orders of magnitude higher than the electrical conductivity of a vapor deposition film using a chemically synthesized complex as a starting material. When performing this co-deposition, for example, argon, nitrogen, hydrogen, helium or the like can be used as an atmospheric gas. The gas pressure of these atmospheric gases is preferably 10 ⁻³ torr or less.

The sublimation rate of the TCNQ compound and the TTF compound is in the range of 1 to 1000 nm / min, preferably 5 to 100 nm / min. In order to set the sublimation rate within the above range, the heating temperature of the sublimation source in which the TCNQ compound and the TTF compound are stored may be preset by a sensor such as a film thickness monitor according to the degree of vacuum. desirable.

Further, the above TCNQ compound and the above TT
The distance between the F-based compound and the substrate is preferably 5 to 30 cm, more preferably 10 to 20 cm.

On the other hand, in the second invention of the present application, the TCNQ-based compound and the TTF-based compound are simultaneously sublimated in plasma to carry out copolymerization to form a polymerized film on the substrate. Thereby, excellent conductivity can be obtained, and mechanical strength and chemical resistance can be improved. When performing this plasma polymerization, as a method for generating plasma, any conventionally known method can be used, and for example, a DC discharge method, a low frequency discharge method, a high frequency discharge method, a microwave discharge method, etc. can be used. is there. Further, the electrodes in these discharge methods may be appropriately selected from an internal electrode method, an external electrode method, a capacitive coupling type, an inductive coupling type and the like.

In this plasma polymerization, the above TCN is used.
The Q-based compound and the TTF-based compound may be used alone, or a carrier gas may be used in combination. In this case, as the carrier gas, any carrier gas generally used in plasma polymerization can be used, and examples thereof include argon, nitrogen, hydrogen and helium. The gas pressure in this plasma polymerization is preferably 10 ^-1 torr or less.

Further, the discharge condition may be appropriately selected within a range where a generally known relational expression between pressure-electrode distance-voltage (Paschen's law) is satisfied when a DC voltage is used. However, when an AC voltage is used, it is not particularly limited as long as it is a dischargeable range.

Further, the sublimation rates of the TCNQ compound and the TTF compound are in the range of 1 to 1000 nm / min, preferably 5 as in the first invention of the present application.
˜100 nm / min. Conditions such as the heating temperature of the sublimation source and the distance between the substrate and each compound for setting the sublimation rate within the above range may be set in the same manner as in the first invention of the present application.

The thickness of the charge transfer complex thin film obtained by the above-mentioned co-deposition or plasma polymerization may be appropriately selected according to the application. For example, when this charge-transfer complex thin film is used as a battery electrode material,
It is desirable that the thickness is about μm. In this case, if the thickness of the charge transfer complex thin film is smaller than the above range, sufficient practicality cannot be satisfied, and conversely, if it is larger than the above range, energy density cannot be secured.

[0028]

As described in the first aspect of the present invention, a complex having high electric conductivity is formed by sublimating a TCNQ compound and a TTF compound individually and performing co-evaporation. Further, as shown in the second invention of the present application, the TCNQ-based compound and the TTF-based compound are individually sublimated in plasma to perform copolymerization, whereby the resulting charge transfer complex is polymerized to have a high mechanical strength. And the chemical resistance is improved.

[0029]

EXAMPLES The present invention will be described below with reference to specific examples, but it goes without saying that the present invention is not limited to these examples.

Example 1 In this example, TCNQ represented by the following formula (4) and TTF represented by the following formula (5) were co-deposited by the vapor deposition apparatus as shown in FIG. This is an example of forming a charge transfer complex thin film.

[0031]

[Chemical 13]

[0032]

[Chemical 14]

First, the structure of the vapor deposition apparatus used in this embodiment will be described. In this vapor deposition apparatus, TCNQ and TTF, which are starting materials, are housed in a central portion of a reaction chamber (volume 210l) 1 kept at a predetermined vacuum degree.
The Mo boards 2 and 3 are arranged. These Mo boards 2 and 3 are respectively connected to DC power supplies 4 and 5 provided outside the reaction chamber 1, and the board temperatures are individually controlled.

Above the Mo boards 2 and 3,
The glass substrate 6 on which the above-mentioned starting materials are deposited is arranged so as to be held by a supporting plate 7 attached to the head of the reaction chamber 1. Then, the TC values in the Mo boards 2 and 3 are controlled by controlling the current values of the DC power supplies 4 and 5.
NQ and TTF are sublimated at the same time by electric heating, and deposited on the glass substrate 6 on the surface facing the Mo boards 2 and 3 to form a charge transfer complex thin film.

This glass substrate 6 and the above Mo boards 2 and 3
A shutter 8 is disposed between the shutters, and opening / closing of the shutter 8 controls vapor deposition on the glass substrate 6. In this example, when the vapor deposition rates of both were stable and became 1: 1, the shutter 8 was opened to perform vapor deposition.

In carrying out such vapor deposition, the board temperature needs to be set in accordance with the degree of vacuum in the reaction chamber 1, and it is desired to obtain it in advance by a sensor such as a film thickness monitor. Here, in order to adjust each Mo board 2 and 3 to a predetermined temperature, the Mo board 2 in which the above TCNQ is accommodated
The current value of the DC power source 4 connected to the
The current value of the DC power supply 5 connected to the Mo board 3 accommodating is about 40A. As a result, the above TCNQ and T
The TF is deposited by stoichiometry at 1: 1. When changing the ratio of TCNQ and TTF,
The current values of the Mo boards 2 and 3 may be appropriately selected.

On the other hand, a gas supply pipe 9 is provided on the side wall of the reaction chamber 1, and the carrier gas in the cylinder 10 is supplied into the reaction chamber 1 through the gas supply pipe 9.
In the middle of the gas supply pipe 9, cocks 11a, 11
b and 11c are provided respectively, and these cocks 1
The amount of Ar gas introduced is controlled by opening / closing 1a, 11b, 11c. As the carrier gas, Ar gas was used here.

At the bottom of the reaction chamber 1, the exhaust port 1
a is opened. An exhaust pipe 13 is provided at the exhaust port 1a.
Are connected, and the rotary / oil diffusion pump 12 is connected via the exhaust pipe 13. At the middle of the exhaust pipe 13, a pressure gauge 14,
A conductance valve 15 and an exhaust cock 16 are provided so that the inside of the reaction chamber 1 can be maintained at a predetermined degree of vacuum.

Further, a gas introducing pipe 17 for leak is arranged in the reaction chamber 1, and nitrogen gas for purging is introduced into the reaction chamber 1 through the gas introducing pipe 17. A leak valve 1 is provided in the middle of the gas introduction pipe 17.
8 is provided and is opened only at the time of leak.

Therefore, TCNQ and TTF are co-deposited in an Ar gas atmosphere by using the vapor deposition apparatus having the above-described structure to form a comb-shaped electrode (composed of a pair of Au electrodes 22 and 23) as shown in FIG. , In which the comb-shaped portions 22a and 23a of the Au electrodes 22 and 23 are formed so as to mesh with each other with a minute gap d), a charge transfer complex thin film is formed on the glass substrate 21. The degree of vacuum in the reaction chamber was set to 0.01 torr or less.

Then, the conductivity of the obtained charge transfer complex thin film was measured as follows.

That is, as shown in FIG. 4, the pair of Au
The charge transfer complex thin film 24 (film thickness b> 2) formed by applying a current between the electrodes 22 and 23 and filling the gap 25 between the Au electrodes 22 and 23 by an impedance analyzer.
The resistance value of 500Å) was measured. The Au electrode 2
The film thickness e of 2, 23 is 2500Å, and the distance d between these Au electrodes 22, 23 is 1 mm. Further, the distance (electrode length) L along the length direction of the gap 25
Is 47 cm.

Then, using the following equation (6), the above Au
Charge transfer complex thin film 24 sandwiched between electrodes 22 and 23
The direct current conductivity σ _{V of} was calculated from the Cole-Cole plot.

[0044]

[Equation 1]

However, in the equation (8), R is the DC component of the resistance value of the charge transfer complex thin film 24, and L is the Au electrode 2
The length of the charge transfer complex thin film 24 sandwiched between 2 and 23, e is the film thickness of the Au electrodes 22 and 23, and d is the inter-electrode distance. As a result, it was found that the charge transfer complex thin film had a direct current conductivity σ _V of 3.5 S / cm and had good conductivity.

Next, the infrared absorption spectrum of this charge transfer complex thin film was investigated. The results are shown in Table 1 below. In Table 1, the starting material was a complex of TCNQ and TTF formed in acetonitrile at a molar ratio of 1: 1 and the sublimation current was 45 A, respectively.
The charge transfer complex thin film (Comparative Example 1) and the TCNQ simple substance (Comparative Example 2) obtained when vapor deposition was performed in the same manner as above were also described.

[0047]

[Table 1]

As shown in Table 1, in the co-evaporated film of TCNQ and TTF (Example 1), 2 caused by C≡N stretching vibration
Since the absorption peak near 230 cm ^-1 is shifted to the lower frequency side than TCNQ alone, TCNQ and TTF
It was confirmed that charge transfer occurred between the molecules of.
In addition, as a result of measuring the DC conductivity in Comparative Examples 1 and 2 as described above, it was found that in Example 1, the conductivity was improved by almost two digits as compared with Comparative Example 1.

Example 2 This example is an example in which a charge transfer complex thin film is formed by plasma polymerization of TCNQ and TTF by a plasma polymerization apparatus as shown in FIG. The plasma polymerization apparatus used in this example has the same basic structure as that of the vapor deposition apparatus used in Example 1 described above. Therefore, in FIG. 2, the same reference numerals are used for members common to the vapor deposition apparatus. , The description was omitted.

As shown in FIG. 2, in this plasma polymerization apparatus, a pair of coupled parallel plate electrodes are arranged opposite to each other in the reaction chamber 1. Among these parallel plate electrodes, the glass substrate 6 on which the above TCNQ and TTF are adhered is fixed to the anode electrode 30 attached to the head of the reaction chamber 1. The anode electrode 30 is connected to the R via an impedance matching device 32 installed on the upper surface of the reaction chamber 1.
It is connected to the F power source 33. As this RF power source 33,
A high frequency power supply device impedance-matched by the impedance matching device 32 is used.

On the other hand, the cathode electrode 31 arranged so as to face the anode electrode 30 is installed at the bottom of the reaction chamber 1. Then, a predetermined discharge voltage is applied between the anode electrode 30 and the cathode electrode 31 by the RF power source 33, so that plasma is generated.
At this time, TCNQ and TTF in the Mo boards 2 and 3 are simultaneously sublimated by controlling the current values of the DC power supplies 4 and 5 by electric heating, and a plasma polymerized film is formed on the glass substrate 6.

Therefore, using a plasma polymerization apparatus having such a structure, TCNQ and TTF in an Ar gas atmosphere.
Then, the charge transfer complex thin film was formed on the glass substrate with the comb-shaped electrodes in the same manner as in Example 1 above. When performing plasma polymerization, the output of the RF power supply is AC 1
It has a maximum output of 150 W at a radio frequency of 3.56 MH and is set to 50 W here. The conditions such as the degree of vacuum in the reaction chamber 1 and the current values of the DC power supplies 4 and 5 connected to the Mo boards 2 and 3 accommodating the TCNQ and TTF are the same as those in the first embodiment. ..

Then, using the obtained charge transfer complex thin film and, as a starting material, a complex of TCNQ and TTF formed in acetonitrile at a molar ratio of 1: 1 for comparison,
A charge transfer complex thin film (referred to as Comparative Example 3) obtained when plasma polymerization was performed in the same manner as in Example 2 except that the sublimation current was set to 45 A, respectively, and TCNQ alone (referred to as Comparative Example 4). The electrical conductivity and infrared absorption spectrum of were measured as described above. The results are shown in Table 2 below.

[0054]

[Table 2]

As shown in Table 2, TC as in this embodiment
For plasma polymerized film of NQ and TTF, 1.9 × 10 ^-2
It was found that a relatively high conductivity was obtained, and that the conductivity was improved by about one digit as compared with the plasma polymerized film using a complex of TCNQ and TTF as a starting material. In this plasma polymerized film, 2230c caused by C≡N stretching vibration
Since the absorption peak near m ^-1 is shifted to the lower frequency side than TCNQ alone, it is presumed that charge transfer occurs between the molecules of TCNQ and TTF, and a good charge transfer complex is formed. It was confirmed that

The molecular weight and molecular weight distribution of the above-mentioned Example 2 and Comparative Example 3 were determined by liquid chromatography (GPC). The results are shown in Table 3 below.

[0057]

[Table 3]

As shown in Table 3, from the result of the molecular weight Mw, the charge transfer complex in Example 2 was sufficiently polymerized, and the molecular weight distribution was small, and the polymer film was uniform. I understood.

Furthermore, when the charge transfer complex thin film obtained in Example 2 was contacted with propylene carbonate, acetonitrile, acetone and nitric acid for 2 days, almost no deterioration of the charge transfer complex thin film was observed. From this, it can be said that the charge transfer complex thin film in this example has very excellent chemical resistance.

[0060]

As is apparent from the above description, in the first invention of the present application, the TCNQ-TTF type charge transfer complex is produced by so-called co-evaporation in which the electron donor and the electron acceptor are individually sublimated. As a result, it became possible to provide a new production method for the method for producing a charge transfer complex, which was conventionally limited to vapor deposition using a needle crystal or a complex as a starting material. With the complex, it is possible to obtain a conductivity that is nearly two orders of magnitude higher than that of a conventional vapor deposition film.

Further, in the second invention of the present application, since the electron donor and the electron acceptor are plasma-polymerized, it is possible to obtain a polymerized and uniform polymerized film having a small molecular weight distribution. This polymer film exhibits good conductivity, and can exhibit excellent chemical resistance and heat resistance. Furthermore, in the first and second inventions of the present application, since it is not necessary to heat the substrate during film formation, it is possible to form a film with good adhesiveness even on a substrate having poor heat resistance, and to obtain a film thickness with good dimensional accuracy. Can be controlled. Therefore, according to the present invention, it is possible to provide an organic conductive material suitable for use as, for example, an electronic material or a battery electrode active material.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of an example of a vapor deposition apparatus used when producing a charge transfer complex to which the present invention is applied.

FIG. 2 is a schematic diagram showing a configuration of an example of a plasma polymerization apparatus used when producing a charge transfer complex to which the present invention is applied.

FIG. 3 is a perspective view showing a configuration of a glass substrate on which comb-shaped electrodes are adhered and formed.

FIG. 4 is a cross-sectional view for explaining a method for measuring the conductivity of a charge transfer complex thin film formed on a glass substrate with comb electrodes.

[Explanation of symbols]

 1 ... Reaction chamber 1a ... Exhaust port 2, 3 ... Mo board 4,5 ... DC power supply 6 ... Glass substrate 8 ... Shutter 12 ... Rotary / oil diffusion pump 30. ..Anode electrode 31 ... Cathode electrode 33 ... RF power source

Claims (2)

[Claims] 1. A method for producing an organic conductive material, which comprises co-evaporating an electron acceptor represented by the following Chemical formula 1 and an electron donor represented by the following Chemical formula 2 or Chemical formula 3. [Chemical 1] [Chemical 2] [Chemical 3] 2. A method for producing an organic conductive material, which comprises polymerizing an electron acceptor represented by the following chemical formula 4 and an electron donor represented by the following chemical formula 5 or 6 by plasma polymerization. [Chemical 4] [Chemical 5] [Chemical 6]