JPH0373961B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for processing organic semiconductor materials. Since this material can in principle be formed into any shape, it is expected to be applied in a variety of fields, such as as a temperature-sensitive resistor material, solid electrolyte material for fixed electrolytic capacitors, solid electrolyte for batteries, and conductive film. has been done. Among organic semiconductors, TCNQ salt is famous as an organic semiconductor with particularly high conductivity. Here
TCNQ is an abbreviation for 7,7,8,8 tetracyanoquinodimethane, and the properties of TCNQ and TCNQ salts can be found in J.Am.Chem.Soc., Vol.84, PP3374~
3387 (1962). However, TCNQ salt is usually a powdery crystal, and although the crystal itself exhibits high electrical conductivity, it is difficult to mold it because of its powdery nature. Conventionally proposed methods for forming TCNQ salt can be classified into the following three types. (1) In solvents such as DMF (dimethylformamide)
A method in which a solution containing TCNQ salt is applied to a substrate of a specified shape, and then dried to remove the solvent by scattering. (2) A method in which fine crystals of TCNQ salt are made using a ball mill or the like and dispersed in alcohol, etc., and then applied to the above substrate and dried. (3) A method of vacuum evaporating TCNQ salt onto the above substrate. In method (1) above, DMF, which has high solubility for TCNQ salt, is used as a solvent, and such a solvent is
Even when heated to ℃, its solubility is limited to 10%. This means that it is necessary to apply and dry the TCNQ salt many times to apply the necessary thickness to a flat substrate, or to apply the TCNQ salt to a porous substrate with sufficient impregnation. are doing. Furthermore, the substrate coated with the solution is left at high temperatures each time it is dried, but at this time the TCNQ salt changes in quality to a greater or lesser extent, leading to deterioration of its conductivity. In addition, since the TCNQ salt deposited on the substrate in this way consists of fine crystals, a coagulating resin such as polyvinylpyrrolidone is actually added to the coating solution to strengthen the adhesion strength of the fine crystals. However, since such a coagulating resin is an electrical insulator, together with the above-mentioned deterioration in conductivity, the conductivity of the TCNQ salt becomes even lower. In method (2) above, there is a limit to the miniaturization of the TCNQ salt, and the adhesion strength to the substrate is particularly weak, so the TCNQ salt may peel off from the substrate. This enhancement of adhesive strength can be improved to some extent by employing a coagulating resin as described above, but this also results in a decrease in the electrical conductivity of the TCNQ salt. Furthermore, since a dispersion solution of fine crystals made of TCNQ salt is used, the impregnation rate into a porous substrate is particularly poor, and even if an ultrasonic diffusion impregnation method is used, the impregnation rate is low. In the method (3) above, not only is the vacuum evaporation work complicated, but it is also completely unsuitable for attachment to porous substrates. The present invention provides a completely new method for processing organic semiconductor materials, more specifically, a method for producing a liquid consisting only of TCNQ salt, cooling and solidifying the liquid, and applying the liquid to a substrate of a predetermined shape. By cooling and solidifying in contact, any shape can be formed.
A semiconductor material consisting of TCNQ salt can be obtained. The most practical way to obtain a liquid consisting only of TCNQ salt is to liquefy the powdered TCNQ salt in its original form by heating and melting it. However, simply heating and melting the TCNQ salt thermally decomposes the TCNQ salt and turns it into almost an electrical insulator. The present invention shows that even if some TCNQ salts are heated and melted, it takes a short time to thermally decompose, but there is sufficient time for adhesion, and therefore it is possible to cool and solidify within such a time. maintains high conductivity if
It is based on the completely new knowledge that TCNQ salt can be obtained. TCNQ and its various salts, as well as its production process, are described in, for example, J.Am.Chem.Soc., Vol.84,
Disclosed in PP3374-3387 (1962). TCNQ
Salts include a single salt represented by M ⁿ + (TCNQ-)n and a complex salt represented by M ⁿ + (TCNQ-)n (TCNQ)m. In addition, the above M is an organic cation,
n means the value of the cation, and m means a positive number corresponding to the number of moles of neutral TCNQ contained in 1 mole of the complex salt. In the present invention, however, the use of complex salts is more preferred. The above m of the complex salt is 0.5 to 1.5, preferably about 1. Examples of TCNQ salts used in the present invention include:
Examples include TCNQ salts of quinoline, isoquinoline and pyridine substituted at the N-position. In addition, the substituent at the N position is _C2 - _C18 (carbon number 2-18) alkyl (e.g. ethyl, propyl, butyl, pentyl, octyl, decyl, octadecyl), _C5 - _C8 cycloalkyl (e.g. cyclopentyl). , cyclohexyl),
Hydrocarbon groups such as _C3 - _C18 alkene (eg allyl), phenyl or phenyl( _C1 - _C18 )alkyl (eg phenethyl). More preferred examples of the TCNQ salt used in the present invention include TCNQ salt of N-n-propylquinoline,
TCNQ salt of N-ethylisoquinoline, TCNQ salt of N-isopropylquinoline, TCNQ salt of N-hexylquinoline, TCNQ salt of N-n-propylisoquinoline, TCNQ salt of N-isopropylisoquinoline, N-n-butylisoquinoline TCNQ salt of N-n-butylpyridine
TCNQ salt). The melting points of various TCNQ salts used in the present invention are described below for nine types of salts shown as P-1 to P-10. P-1...N-n-propylquinoline ⁺ (TCNQ-)
(TCNQ) P-2...N-isopropylquinoline ⁺ (TCNQ-)
(TCNQ) P-3...N-n-propylisoquinoline ⁺
(TCNQ-) (TCNQ) P-4...N-isopropylisoquinoline ⁺
(TCNQ−) (TCNQ) P-5…N-n butylisoquinoline ⁺ (TCNQ−)
(TCNQ) P-6...N-ethylquinoline ⁺ (TCNQ−)
(TCNQ) P-7...N-ethylisoquinoline ⁺ (TCNQ-)
(TCNQ) P-8...N-n-hexylquinoline ⁺ (TCNQ-)
(TCNQ) P-9...N-n-hexylisoquinoline ⁺

[Table] The production of each of the above salts is, for example, as follows. N-
Alkyl iodo and quinoline (or isoquinoline,
TCNQ salt is obtained by reacting N-alkylquinoline (or isoquinoline, pyridine) iodide obtained by reacting N-alkylquinoline (or isoquinoline, pyridine) iodide with TCNQ in an appropriate molar ratio (e.g. 3:4) in an appropriate solvent (e.g. acetonitrile). make. Since this salt contains many impurities, the purity of the salt can be increased by repeating a recrystallization operation consisting of heating dissolution, cooling, and crystallization in an appropriate solvent (for example, acetonitrile at a temperature of 82° C. or lower). The resulting crystals are needle-shaped or rod-shaped powders. The molar ratio of the quinoline (or isoquinoline, pyridine) moiety to the TCNQ moiety varies slightly depending on the type of solvent used in the above reaction or purification.
For example, if the solvent used in the reaction and in the purification work is acetonityl, a complex salt with m of 1 is
TCNQ salt is usually obtained, but when it is methanol during purification work, m is less than 1. The above molar ratio changes even if pulverized TCNQ is mixed into the TCNQ salt. For example, a melt-solidified salt obtained by mixing 5% TCNQ into a TCNQ salt with m of 1 has m of about 1.14. In this way, it can be used even if m changes slightly from 1. TCNQ salts not included in the present invention, such as TCNQ salts of H-quinoline (or isoquinoline) and TCNQ salts of N-methylquinoline (or isoquinoline), decompose without melting when heated, or decompose simultaneously with melting. . In contrast, the objects of the present invention as described above
When TCNQ salt is heated, it melts and becomes liquefied, but it takes a substantial amount of time for it to decompose thermally in that state. Thermal decomposition in this case occurs suddenly and the salt becomes an electrical insulator. The time required for insulation after complete melting is as follows.

[Table] However, heating was performed by filling an aluminum case with TCNQ salt crystal powder and bringing it into contact with a metal plate at the above temperature. Therefore, TCNQ salt in liquefied state must be cooled and solidified before its decomposition. Thereby, a semiconductor with high electrical conductivity is obtained. For example, in the case of P-1 and P-2, it is heated to a temperature above the melting point and below about 300°C, and after completion of liquefaction at 260°C, for example, 10
Cooling at room temperature or in a coolant such as water begins within seconds, preferably within 5 seconds. P-3, P-4, and P-5 are heated to a temperature above the melting point and below about 320°C, for example 260°C, and after liquefaction is completed, the temperature is about 70°C.
Cooling at room temperature or in a coolant such as water begins within seconds, preferably within one minute. In this way, it is obtained by cooling and solidifying before decomposition.
The conductivity of TCNQ salt is as follows.

[Table] The semiconductor obtained by the present invention is the conventional method (1) or
It is not a collection of microcrystals of TCNQ salt like in case (2), but is almost in the state of a polycrystalline mass. According to the present invention, it is the same as attaching TCNQ salt to the substrate using a solution containing 100% TCNQ salt, so it is completely different from the conventional method (1) described above, and almost all the attaching work is done in one time. , it is possible to form the required amount of TCNQ salt even when the substrate is not only foil-like but also porous, which not only improves mass productivity but also overcomes the conventional drawback that TCNQ salt deteriorates every time it is dried. be done. Furthermore, according to the present invention,
Because the shaped TCNQ salt is close to an amorphous state,
The adhesion force to the substrate is sufficiently large, so that there is no need to use a conventional coagulating resin, and an undesired decrease in the conductivity of the TCNQ salt can be avoided. Embodiments of the present invention will be described below, taking as an example the case of manufacturing a solid electrolytic capacitor. First, the TCNQ salt of N-isopropylquinoline is prepared. The preparation of such TCNQ salt itself is described in the above-mentioned document J.Am.Chem.Soc., Vol.84, pp3374-3387.
(1962), but to put it simply, isopropyl quinoline iodide is produced by reacting isopropyl iodide with quinoline, and a solution of TCNQ in acetonitrile is prepared, and these are mixed into approximately 3 : 4 moles of N-isopropylquinoline in powder crystal form by reacting with
TCNQ salt is made. From now on, simply use this salt as TCNQ
It's called salt. On the other hand, as shown in FIG. 1, a porous capacitor element 1 as a film-forming metal having an oxide film was prepared by anodizing a sintered body of aluminum powder according to a normal manufacturing method for solid electrolytic capacitors. be done. After the above preparation, the step to be carried out is to impregnate the capacitor element 1 with a solid electrolyte consisting of TCNQ salt. That is, as shown in FIG. 2, the prepared powder TCNQ salt is stored in an aluminum container 2 under moderate pressure, and the container 2 is heated to provide a TCNQ salt bath 3 in which the TCNQ salt is melted and liquefied. The temperature of this bath is maintained below 270°C.
Note that pressurizing the aluminum container 2 when storing TCNQ salt is not essential. In the following process, as shown in Figure 3, the temperature is preliminarily heated to 260℃.
Capacitor element 1 heated and maintained at ~270℃
immersed in TCNQ salt bath 3, immediately pulled out,
Leave at room temperature. As a result, the TCNQ salt impregnated into the porous capacitor element 1 is cooled and solidified.
It becomes the desired solid electrolyte. The time required from liquefaction to cooling solidification of the TCNQ salt is about 10 seconds. In the remaining steps, as is usual, the impregnated capacitor element 1' is prepared as shown in FIG.
A graphite layer 4 and a silver paint layer 5 are sequentially applied to the surface, and finally the element 1 is housed together with a cathode lead wire 6 in an aluminum container 7 and fixed with solder 8 and epoxy resin 9. As the element 1, a conventional capacitor having a capacitance of 1 μF using manganese dioxide as a solid electrolyte was used, and the capacitance of the completed capacitor was 0.75 μF. This means an impregnation rate of 75%, assuming that the impregnation rate in the case of manganese dioxide is 100%. Also, as mentioned above, the life test results of the 0.75 μF capacitor were good as shown in the following table.

[Table] Next, as a second embodiment of the present invention, a case of manufacturing a temperature-sensitive resistor will be described. First, as shown in FIG. 5, a glass substrate 10 is prepared, and the substrate is immersed in the TCNQ salt bath 3 in the same manner as in FIG. 2, immediately taken out, and left at room temperature. As a result, as shown in FIG. 6, an organic semiconductor film 11 made of TCNQ salt is attached around the substrate 10. The holding temperature of the TCNQ salt bath 3 and the time from liquefaction to cooling solidification of the TCNQ salt are the same as in the first embodiment. Next, as shown in FIG. 7, the substrate 10 having the organic semiconductor film 11 is fixed onto a resin substrate 13 having a normal copper printed circuit 12, and both ends of the organic semiconductor film 11 and the copper printed circuit 12 are made conductive. They are bonded with paint 14, and the desired temperature-sensitive resistor is completed. FIG. 8 shows the temperature characteristics of such a resistor. As is clear from the above explanation, according to the present invention
An organic semiconductor made of TCNQ salt can be easily attached to a substrate of a predetermined shape, and the TCNQ salt is hardly deteriorated during such an attachment operation.

[Brief explanation of drawings]

1 to 4 are step-by-step diagrams illustrating a method according to an embodiment of the present invention, with FIG. 1 being a side view and FIGS. 2 to 4 being sectional views. FIGS. 5 to 7 are cross-sectional views showing other embodiments of the present invention by process, and FIG. 8 is a temperature characteristic diagram. 3...TCNQ salt bath, 11...Organic semiconductor film.

Claims (1)

[Claims] 1. A TCNQ complex salt of quinoline, isoquinoline or pyridine substituted with a hydrocarbon group at the N-position is liquefied by heating and melting, and the TCNQ complex salt is cooled and solidified within the time until the TCNQ complex salt is thermally decomposed. A method for processing organic semiconductor materials. 2. A method for treating an organic semiconductor material according to claim 1, wherein the hydrocarbon group is an alkyl group having 2 to 18 carbon atoms. 3. Treatment of an organic semiconductor material according to claim 2, characterized in that the molar ratio of TCNQ to quinoline, isoquinoline, or pyridine substituted with an alkyl group having 2 to 18 carbon atoms is approximately 2:1. Method.