JP4243687B2 - Organic-inorganic hybrid thin film and method for producing the same - Google Patents

Description

The present invention relates to an organic-inorganic hybrid thin film and a method for producing the same, and more particularly, to a highly oriented thin film of molybdenum oxide prepared on a metal oxide single crystal substrate, a conductive polymer such as polypyrrole or a butylammonium salt. The present invention relates to a method for producing a high-quality electrically conductive organic-inorganic hybrid thin film having a uniform film thickness by a method of intercalating organic ions, and the like, and an organic-inorganic hybrid thin film produced by the method.
In the technical field of highly functional hybrid materials in which organic compounds and inorganic compounds are combined at the nano level, the present invention has a problem in adhesion to the substrate in the conventional hybrid thin film, and is easily peeled off. In light of the fact that there is a problem, and hybrid materials with excellent conductivity have not been obtained, the functions of organic compounds and inorganic compounds are shared, and these are compounded at the fine nano-level, making them conventional products. It is possible to drastically solve various problems in, for example, succeeded in establishing a manufacturing technique of a conductive organic-inorganic hybrid thin film mainly composed of molybdenum oxide. New conductivity that makes it possible to produce high-quality conductive organic-inorganic hybrid thin films that can be used as electrodevice materials The method of manufacturing machine inorganic hybrid film, and its products, in particular, is useful for providing a new type of chemical sensor member which responds by sensor resistance to VOC gas increases.

  Organic-inorganic hybrid materials are a new type of material that combines the excellent heat resistance and mechanical strength of inorganic compounds with the excellent chemical properties of organic compounds. Optical, electrical, or mechanical properties The hybrid material is expected to be applied to various fields because of its characteristic functions such as characteristics. Among them, organic-inorganic hybrid materials exhibiting electrical conductivity have been reported to have high potential for application to, for example, light-emitting elements, transistors, batteries, chemical sensors, and the like.

  In particular, for chemical sensor applications, organic compounds with a molecular recognition function and inorganic compounds with the function of converting chemical information, such as the presence or absence of the gas to be detected, into electrical signals and outputting them to the outside, are at the nano level. It is effective to improve the gas selectivity to use a hybrid material compounded with. This is because the organic compound and the inorganic compound share the function, and by combining these at a fine level, the organic compound has high selectivity and the high stability of the inorganic compound, and signals can be easily transmitted. It is a new concept that a sensor that can be taken out to the outside can be manufactured, and the intercalated organic-inorganic hybrid material manufactured based on this concept has excellent gas selectivity for volatile organic compound gas. There is expected.

  As can be seen from examples of gas sensors, many organic-inorganic hybrid materials having an excellent function have been reported so far. For example, development of a thin film technology is indispensable for application as these elements. In general, inorganic compounds or organic compounds, thin films of the respective compounds, for example, sputtering method, laser ablation method, molecular beam epitaxy method, electron beam evaporation method, metal organic chemical vapor deposition method, sol-gel method, coating pyrolysis method, etc. It is made with. However, in the organic-inorganic hybrid material, the vapor pressure and chemical properties of the constituent inorganic compound and the organic compound are greatly different, so that it is not easy to make a thin film by the above-described conventional method.

  Until now, the typical thinning technology reported for intercalated organic-inorganic hybrid materials has a layered structure in which a host inorganic compound and a guest organic compound are colloidal in a solvent. This is a technique for forming a film on a substrate by utilizing a self-assembly phenomenon (Delamination / Reassembling Process) (Non-Patent Documents 1 to 3).

On the other hand, when the inorganic compound is, for example, a metal halide such as PbI ₄ , since the vapor pressure of the inorganic compound is relatively high, thinning is achieved by thermal evaporation (Patent Document 1, Non-Patent Document). 4). In addition, an intercalated organic-inorganic hybrid thin film having a transition metal oxide as a host and an organic ion as a guest is produced by a method of forming a host compound and then intercalating the guest compound (patent) Reference 2).

  In the Delamination / Reassembling Process, a conductive hybrid thin film using a metal oxide as a host can be produced. However, this thin film has a problem in adhesion to the substrate and easily peels off. Thermal evaporation is a method that can be applied only to special inorganic compounds. In addition, a conductive hybrid film is not obtained by a method of intercalating organic ions serving as guests after forming an inorganic compound serving as a host. As described above, a method for producing a conductive organic-inorganic hybrid thin film mainly composed of molybdenum oxide has not yet been established.

JP 2002-198539 A Special Table 2002-114593 Chem. Mater., 14, 4800-4806 (2002) Chem. Mater., 15, 2873-2878 (2003) Chem. Mater., 9, 857-878 (1997) IBM J. Res. & Dev. 45, 29-45 (2001)

Under such circumstances, the present inventors have aimed to develop a method for producing a conductive organic-inorganic hybrid thin film mainly composed of molybdenum trioxide (MoO ₃ ) in view of the above-described conventional technology. As a result of repeated research, as a result of intercalating hydrated sodium ions to a highly oriented film of molybdenum oxide fabricated by CVD on a metal oxide single crystal substrate similar in lattice constant to inorganic compounds, By the method of substituting with a conductive polymer or organic ions, it is possible to obtain a homogeneous organic-inorganic hybrid thin film having excellent adhesion to the substrate, and the obtained thin film has electrical conductivity. It came to complete.
An object of the present invention is to provide a method for producing a high-quality organic-inorganic hybrid thin film having conductivity, the organic-inorganic hybrid thin film, a conductive member, and a new type of sensor member. .

The present invention for solving the above-described problems comprises the following technical means.
(1) A conductive organic-inorganic hybrid thin film in which a highly oriented thin film of an inorganic compound having a layered structure is intercalated with a hydrated alkali metal ion and further substituted with an organic compound ,
The inorganic compound having the layered structure is mainly composed of molybdenum oxide, and the highly oriented thin film is b-axis oriented on a metal oxide single crystal substrate having a lattice constant similar to that of the inorganic compound. An organic-inorganic hybrid thin film characterized by being a highly oriented thin film.
( 2 ) The organic-inorganic hybrid thin film according to (1), wherein the organic compound is a conductive polymer.
( 3 ) The organic-inorganic hybrid thin film according to (1), wherein the organic compound is an organic ion.
( 4 ) A method for producing a conductive organic-inorganic hybrid thin film,
1) A highly oriented thin film of an inorganic compound is produced by producing a highly oriented thin film of an inorganic compound that is b-axis oriented on a metal oxide single crystal substrate having a lattice constant similar to that of an inorganic compound having a layered structure. ) intercalated hydrated alkali metal ions in the high oriented thin film, 3) is replaced with this organic compound consists step, an inorganic compound having the layered structure is composed mainly of molybdenum oxide ,
A method for producing an organic-inorganic hybrid thin film.
( 5 ) The method for producing an organic-inorganic hybrid thin film according to ( 4 ), wherein the organic compound is a conductive polymer.
( 6 ) The method for producing an organic-inorganic hybrid thin film according to ( 4 ), wherein the organic compound is a cationic organic compound.
( 7 ) An electroconductive member comprising the organic-inorganic hybrid thin film according to any one of (1) to ( 3 ) as a constituent element.
( 8 ) A chemical sensor member comprising the organic-inorganic hybrid thin film according to any one of (1) to ( 3 ) as a constituent element.

Next, the present invention will be described in more detail.
As described above, the present invention intercalates a highly oriented thin film of an inorganic compound having a layered structure with a hydrated alkali metal ion, and further replaces the organic compound with an organic compound. The present invention is characterized by manufacturing a type organic-inorganic hybrid thin film. In the present invention, to produce an intercalated organic-inorganic hybrid thin film, (1) preparation of a highly oriented thin film of molybdenum trioxide (MoO ₃ ), (2) formation of hydrated alkali ions on the molybdenum trioxide thin film It is necessary to go through three steps: intercalation and (3) a substitution reaction between a hydrated alkali ion and a conductive polymer or organic ion. Below, each process is demonstrated in detail.

  First, it is important that the molybdenum trioxide thin film produced in step (1) is oriented so that the layer direction of molybdenum trioxide having a layered structure is parallel to the substrate. FIG. 1 shows a schematic diagram of the crystal structure of molybdenum trioxide. Six oxygens coordinate with molybdenum to form an octahedral structure. This octahedron becomes a sheet spread two-dimensionally by sharing a ridge, and these are laminated to form a layer structure. In the crystal axis, the direction perpendicular to the layer corresponds to the b-axis, and the layer direction is parallel to the ac plane. When, for example, polypyrrole is intercalated between molybdenum trioxide layers having such a structure, the interlayer distance increases by about 50%, and large volume expansion occurs in the b-axis direction. For this reason, when the molybdenum trioxide thin film is a non-oriented film, a large strain is generated in all directions during the intercalation process, and the film is peeled off from the substrate.

  On the other hand, in the case of a thin film oriented so that the layer direction of molybdenum trioxide having a layered structure is parallel to the substrate, the expansion direction is only perpendicular to the substrate surface, so that the problem of peeling can be avoided. Therefore, in order to produce an intercalated organic-inorganic hybrid thin film using the target molybdenum trioxide as the host compound, the molybdenum trioxide thin film as the precursor is oriented so that the layer direction is parallel to the substrate. It must be a thin film.

  The method for forming molybdenum trioxide is not particularly limited as long as the alignment film can be obtained. However, the most common sputtering method forms a film under high vacuum. In order to fully oxidize, annealing treatment in an oxidizing atmosphere is required. On the other hand, the CVD method, which enables film formation under a relatively low vacuum by appropriately selecting raw materials, eliminates the need for annealing treatment by optimizing the film formation conditions, and enables efficient thin film production. In the present invention, for example, the CVD method is preferably used.

As for the molybdenum source in the CVD method, it is desirable to form a film under a vacuum condition as low as possible from the viewpoint of efficient film formation. Therefore, it is necessary to select a compound that can generate a high vapor pressure even under a low vacuum. In the present invention, for example, hexacarbonylmolybdenum (Mo (CO) ₆ ) is preferably used, but is not limited thereto. From the viewpoint of lattice matching with the ac surface of molybdenum trioxide, for example, a metal oxide single crystal having a perovskite structure with a small lattice constant mismatch is used for the substrate. Specifically, a (100) plane of LaAlO ₃ or SrTiO ₃ is used, but is not limited thereto.

The substrate temperature in the CVD method using hexacarbonylmolybdenum as a raw material is usually 400 to 540 ° C., preferably 480 to 520 ° C. When the substrate temperature is 400 ° C. or lower, molybdenum trioxide is not sufficiently crystallized. On the other hand, in the case of 540 ° C. or higher, a crystal phase having a small amount of oxygen relative to MoO ₃ is precipitated as impurities. As the carrier gas, oxygen gas is used, and the flow rate is 50 to 300 ml, preferably 70 to 150 ml. The degree of vacuum is 1 to 15 Torr, preferably 3 to 10 Torr. The film forming time has a correlation with the film thickness, and the film thickness increases as the film forming time is increased, but it is usually about 5 to 90 minutes, preferably about 10 to 30 minutes.

  Regarding the film thickness, it also depends on the substrate temperature at the time of film formation and the degree of vacuum. As an example, the film thickness of a molybdenum trioxide thin film formed at a substrate temperature of 500 ° C., an oxygen gas flow rate of 100 ml / min, a degree of vacuum of 7 Torr, and a film forming time of 15 minutes is 110 nm. Since all diffraction peaks observed in the X-ray diffraction pattern of the prepared thin film can be indexed at (0k0), and diffraction peaks having other indices are hardly observed, the molybdenum trioxide thin film is b-axis oriented. That is, it can be confirmed that the layer direction shown in FIG. 1 is oriented so as to be parallel to the substrate.

  On the other hand, for example, when MgO (100) single crystal having a large lattice constant mismatch with molybdenum trioxide is used for the substrate, an impurity phase is not observed even under the same film forming conditions, but the X-ray diffraction pattern ( A diffraction peak having an index other than 0 k0) is observed, and a sufficient b-axis alignment film cannot be obtained. Note that hexacarbonylmolybdenum generates a sufficiently high vapor pressure even at room temperature under the above-described vacuum, and thus does not need to be heated. As described above, according to the manufacturing method, the b-axis alignment film of molybdenum trioxide can be manufactured in a short time without performing the heat treatment after the film formation.

Next, in step (2), hydrated alkali ions are intercalated into the molybdenum trioxide thin film. After bubbling distilled water for about 10 minutes with argon gas, sodium dithionite (Na ₂ S ₂ O ₄ ) and sodium molybdate (Na ₂ MoO ₄ ) are added and dissolved by stirring. A molybdenum trioxide oriented thin film is immersed here. The immersion time is usually about 5 to 120 seconds, preferably about 10 to 60 seconds. During this time, the colorless molybdenum trioxide thin film turns blue, and it can be confirmed that molybdenum trioxide is reduced and hydrated sodium ions are intercalated.

After the immersion, the thin film is washed with distilled water and dried to obtain a [Na (H ₂ O) ₂ ] _x MoO ₃ thin film in which hydrated sodium ions are intercalated between the molybdenum oxide layers. The progress of the intercalation reaction can be confirmed from the X-ray diffraction pattern. Due to the intercalation of hydrated sodium ions, the layer of molybdenum trioxide spreads, and the diffraction peak indexed at (0k0) shifts to the lower angle side.

Next, in step (3), a substitution reaction between the hydrated alkali ion and the conductive polymer or organic ion is performed. For example, in a substitution reaction with polypyrrole, which is a typical conductive polymer, first, pyrrole is added to distilled water, and after sufficiently stirring and mixing using an ultrasonic homogenizer, an oxidizing agent is added and further stirred. The [Na (H ₂ O) ₂ ] _x MoO ₃ thin film is immersed therein. The immersion time is usually 3 to 5 minutes, preferably about 10 to 60 seconds. A PPy _x MoO ₃ thin film is obtained by taking out the thin film, washing and drying.

The oxidizing agent used here is not particularly limited as long as it can oxidize pyrrole, and examples thereof include iron chloride, ammonium peroxodisulfate, and iron nitrate. The amount of pyrrole added is usually 50 to 200 times equivalent, preferably 100 to 150 times equivalent to [Na (H ₂ O) ₂ ] _x MoO ₃ . The addition amount of the oxidizing agent is usually 1 to 3 times equivalent, preferably 1.5 to 2 times equivalent to [Na (H ₂ O) ₂ ] _x MoO ₃ .

In the substitution reaction with organic ions, for example, when butyl ammonium ions (C ₄ H ₉ NH ₃ ⁺ ) are used as organic ions, first, butyl ammonium chloride (C ₄ H ₉ NH ₃ Cl) is dissolved in distilled water. Here, a [Na (H ₂ O) ₂ ] _x MoO ₃ thin film is immersed. The immersion time is usually about 3 to 15 minutes, preferably about 5 to 10 minutes. The (C ₄ H ₉ NH ₃ ) _x MoO ₃ thin film is obtained by taking out the thin film, washing and drying. The amount of C ₄ H ₉ NH ₃ Cl added is usually 1 to 10 times equivalent, preferably 2 to 7 times equivalent to [Na (H ₂ O) ₂ ] _x MoO ₃ .

Using the MoO ₃ thin film prepared on the MgO (100) single crystal substrate shown in the description of the step (1) above, when the intercalation reaction of hydrated sodium ions is performed in the same manner as described above, the reaction As the process progresses, the thin film peels from the substrate. This is presumably because the b-axis orientation of the MoO ₃ thin film on the MgO substrate was not sufficient, so that distortion occurred in all directions due to volume expansion accompanying intercalation. Compared with LaAlO ₃ or SrTiO ₃ , MgO has poor lattice constant matching with molybdenum trioxide, and the b-axis alignment film does not grow. Therefore, in order to produce an organic-inorganic hybrid thin film by an intercalation reaction, it is indispensable to produce a highly oriented film of molybdenum trioxide serving as a host.

  A sensor element produced by depositing a gold electrode on the organic-inorganic hybrid thin film has excellent sensor characteristics against VOC gas. Usually, a resistance change type sensor made of an existing n-type semiconductor oxide responds to a VOC gas when the resistance value decreases. However, the thin film sensor obtained by the present invention has an increased sensor resistance with respect to the VOC gas in any sample composed of a conductive polymer as an organic substance and an organic ion as an organic substance. To respond. Furthermore, since the sensor according to the present invention exhibits a response at room temperature, a heating mechanism or the like is not particularly required, so that the sensor unit can be miniaturized.

  In the method for producing the organic-inorganic hybrid thin film of the present invention, the same method as that in the case of using molybdenum oxide and polypyrrole or butylammonium ion is applied, and a layered inorganic compound and conductive polymer or organic other than molybdenum oxide and polypyrrole or butylammonium ion It can also be applied to ions. As a layered inorganic compound that can form a gas sensor with a conductive organic-inorganic hybrid thin film, for example, tungsten oxide, vanadium oxide, niobium oxide, ruthenium chloride, iron oxychloride, molybdenum sulfide, etc., and as a conductive polymer, For example, polyaniline, polythiol, polyethylene oxide, and the like, and organic ions include, for example, tetrabutylammonium ion, tetraphenylphosphonium ion, etc., but are not limited thereto, and have the same effect or similar to these. Can be used in the same manner.

  According to the present invention, (1) it is possible to manufacture and provide a novel conductive intercalated organic / inorganic hybrid thin film material in which an organic compound and an inorganic compound are combined at a molecular level by a simple process. (2) Molybdenum oxide A method for producing a conductive organic-inorganic hybrid thin film as a main component and a product thereof can be provided. (3) A high-quality conductive organic-inorganic hybrid thin film having a uniform film thickness that can be used as an electro device material can be produced. (4) It is possible to provide a new type of sensor element that responds to an increase in sensor resistance against VOC gas. (5) Intercalated organic-inorganic hybrid thin film using an inorganic compound as a host and an organic compound as a guest. (6) The hybrid thin film is useful as a material for conductive members and sensor members, for example. , Special effects that can be attained.

  EXAMPLES Next, although this invention is demonstrated concretely based on an Example, this invention is not limited at all by the following Examples.

(1) using the CVD method in the production of manufactured MoO ₃ thin MoO ₃ film. A 10 mm square LaAlO ₃ (100) single crystal was used as the substrate. The substrate was set in a holder having a heater for heating. 0.9 g of hexacarbonylmolybdenum (Mo (CO) ₆ ), which is a molybdenum source, was placed in a quartz glass boat and set in a source chamber. Oxygen gas (100 ml / min) was allowed to flow through the entire system including the sample chamber and the source chamber, the sample chamber portion was heated to 460 ° C. by an electric furnace, and the substrate temperature was set to 500 ° C. by a substrate heating heater. After the substrate temperature was stabilized, the entire system was evacuated with a vacuum pump, and the degree of vacuum was adjusted to 7 Torr. When the entire system was depressurized, the volatilization of Mo (CO) ₆ started and the growth of the MoO ₃ film started. Mo (CO) ₆ as the source did not need to be heated, and the source was kept at room temperature. After film formation for 15 minutes under reduced pressure, the entire system was returned to atmospheric pressure. Thereby, volatilization of the source was suppressed and film formation was completed.

The X-ray diffraction pattern of the obtained thin film is shown in FIG. Except for the peak from the substrate, all observed diffraction peaks can be indexed to (0k0) of MoO ₃ having the structure shown in FIG. 1, and a b-axis alignment film of MoO ₃ is grown. Further, the full width at half maximum of the (040) peak rocking curve (θ scan) is 0.65 degrees, and it has high crystallinity. FIG. 3 is a scanning electron microscope (SEM) photograph of the MoO ₃ thin film surface. Although some crystal grains can be seen, the flat and smooth surface is expanded. The film thickness obtained from SEM observation of the cross section is 110 nm.

(2) Preparation of [Na (H ₂ O) ₂ ] _x MoO ₃ Thin Film After 25 ml of distilled water was bubbled with argon gas for 10 minutes in an eggplant type flask, sodium dithionite Na ₂ S ₂ O ₄ (0.2 g , 1.1 mmol) and sodium molybdate Na ₂ MoO ₄ 2H ₂ O (6 g, 24.8 mmol) were added and dissolved by stirring. A MoO ₃ oriented thin film was immersed here for 10 seconds. During this time, the colorless molybdenum trioxide thin film turned blue. After soaking, the thin film was washed with distilled water and dried in air at 125 ° C. for about 30 minutes. The X-ray diffraction pattern of this thin film sample is shown in FIG. Peaks indexed at (0k0) are observed, but these peaks are shifted to the lower angle side compared to MoO ₃ , and it can be seen that the interlayer distance is increased. The interlayer distance obtained from FIG. 4A is 0.97 nm, which is an increase of 0.28 nm compared to the interlayer distance of MoO ₃ (0.69 nm). The spread of the interlayer distance corresponds to the case where the hydrated sodium ion Na (H ₂ O) ₂ is intercalated, so that a [Na (H ₂ O) ₂ ] _x MoO ₃ thin film is formed. It could be confirmed.

(3) Production of PPy _x MoO ₃ thin film After adding pyrrole (2.0 ml, 28.9 mmol) in 25 mL of distilled water and treating with an ultrasonic homogenizer for 3 minutes, iron chloride FeCl ₃ (0.086 g, 0.086 g, 0.51 mmol) was added and stirred at room temperature for 10 minutes. The above [Na (H ₂ O) ₂ ] _x MoO ₃ thin film was immersed therein for 5 minutes. The thin film was taken out and immersed again in the above solution to which 20 ml of ethanol was added for 2 minutes, washed once with distilled water and four times with ethanol, and dried in air at 125 ° C. for about 60 minutes. The X-ray diffraction pattern of this thin film sample is shown in FIG. Peaks indexed at (0k0) are observed, but these peaks are shifted to the lower angle side compared to [Na (H ₂ O) ₂ ] _x MoO ₃ , and the interlayer distance increases. I understand that. The interlayer distance obtained from FIG. 4B is 1.47 nm, which is an increase of 0.78 nm compared to the interlayer distance of MoO ₃ (0.69 nm). Since the spread of the interlayer distance corresponds to the case where polypyrrole is intercalated, it was confirmed that a PPy _x MoO ₃ thin film was formed.

(4) Evaluation of electrical characteristics and sensor characteristics A gold comb-shaped electrode was deposited on the obtained PPy _x MoO ₃ thin film to prepare a sensor element. The electric resistance value measured by the direct current two-terminal method was 0.77 MΩ at room temperature. The sensor characteristics of the PPy _x MoO ₃ thin film sensor with respect to formaldehyde gas were evaluated by the change in electric resistance value. The formaldehyde gas concentration used was 800 ppm, and the measurement was performed at room temperature. FIG. 5 shows a change in resistance value when clean air (25 minutes), sample gas (15 minutes), and clean air are sequentially flowed. The vertical axis in FIG. 5 is the resistance value normalized by the initial resistance. It can be seen that the resistance value of the sensor increases with respect to formaldehyde, and returns to the original resistance value in clean air, which clearly functions as a sensor. Furthermore, sensor characteristics for VOC gases other than formaldehyde were evaluated using a sealed sensor characteristic evaluation apparatus. VOC was vaporized by supplying liquid VOC to the heater in the container, a VOC environment having a predetermined concentration was created, and a change in the resistance value of the sensor was measured.

  FIG. 6 shows sensor sensitivity (Rgas / Ra: Ra is an initial resistance value, and Rgas is a resistance value in a gas atmosphere) for various VOC gases having a concentration of 1000 ppm at room temperature. This sensor does not respond to toluene, but selectively responds to aldehydes, alcohols, and chlorinated gases. Among them, particularly high sensitivity to formaldehyde and acetone was shown. This indicates that the organic-inorganic hybrid thin film sensor of the present invention has high selectivity for VOC gas.

In this example, the substrate temperature when producing the MoO ₃ thin film was set to 520 ° C., and the amount of Na ₂ S ₂ O ₄ when producing the [Na (H ₂ O) ₂ ] _x MoO ₃ thin film was set to 0.1. The method of Example 1 was followed except that the amount was 4 g (2.2 mmol), and the immersion time of the MoO ₃ thin film when producing the [Na (H ₂ O) ₂ ] _x MoO ₃ thin film was 50 seconds. Similarly, a PPy _x MoO ₃ thin film was prepared. The film thickness of the MoO ₃ thin film is 350 nm, and the growth rate tends to increase as the substrate temperature increases. FIG. 7 shows X-ray diffraction patterns of the MoO ₃ thin film, the [Na (H ₂ O) ₂ ] _x MoO ₃ thin film, and the PPy _x MoO ₃ thin film. As in Example 1, it was confirmed that the interlayer distance was increased by intercalation, and a PPy _x MoO ₃ thin film was formed. In order to investigate the crystallinity of the MoO ₃ thin film in more detail, X-ray pole figure measurement was performed. FIG. 8 shows a pole figure of MoO ₃ (021). In the sample with perfectly in-plane orientation, four poles are observed every 90 degrees in the β direction. However, since eight poles appear regularly, two domains with slightly different crystal orientations (about 4 degrees) are observed. From this, it is considered that a MoO ₃ thin film is formed.

However, the peak is very sharp. The half width of the peak appearing in the β scan of MoO ₃ (021) shown in FIG. 9 is 0.4 degrees, which indicates that it has a high in-plane orientation. That is, the MoO ₃ thin film produced in the present invention realizes not only b-axis orientation but also in-plane orientation. From the comparison with the pole figure of LaAlO ₃ (111) as the substrate, it became clear that (100) of LaAlO ₃ and (100) of MoO ₃ were epitaxially grown in parallel. Thus, it is considered that the use of a MoO ₃ thin film having a high orientation is one of the reasons why the film can be converted into a PPy _x MoO ₃ thin film without being peeled by an intercalation reaction.

A gold comb-shaped electrode was deposited on the obtained PPy _x MoO ₃ thin film to produce a sensor element. The electrical resistance value of this sensor measured by the direct current two-terminal method was 1.3 MΩ at room temperature. The sensor characteristics of the PPy _x MoO ₃ thin film sensor with respect to formaldehyde gas were evaluated by the change in electric resistance value. FIG. 10 shows the sensor response of this sensor to 100 ppm of formaldehyde gas. As shown in this figure, the resistance value increases with respect to formaldehyde gas, and the resistance value decreases when the flow of formaldehyde gas is stopped. Therefore, it can be seen that the sensor element functions as a sensor. .

The substrate temperature when producing the MoO ₃ thin film was 480 ° C., and the amount of Na ₂ S ₂ O ₄ when producing the [Na (H ₂ O) ₂ ] _x MoO ₃ thin film was 0.4 g (2.2 mmol). PPy _x MoO in accordance with the method of Example 1 except that the immersion time of the MoO ₃ thin film when producing the [Na (H ₂ O) ₂ ] _x MoO ₃ thin film was 50 seconds. ₃ thin films were prepared. The film thickness of the MoO ₃ thin film was 106 nm. 11 shows X-ray diffraction patterns of the MoO ₃ thin film, [Na (H ₂ O) ₂ ] _x MoO ₃ thin film, and PPy _x MoO ₃ thin film. As in Example 1, it was confirmed that the interlayer distance was increased by intercalation, and a PPy _x MoO ₃ thin film was formed.

In this example, an example of producing an organic-inorganic hybrid thin film in which butylammonium ions (C ₄ H ₉ NH ₃ ⁺ ) as organic ions are intercalated between MoO ₃ layers is shown. The substrate temperature when producing the MoO ₃ thin film was 520 ° C., and the amount of Na ₂ S ₂ O ₄ when producing the [Na (H ₂ O) ₂ ] _x MoO ₃ thin film was 0.4 g (2.2 mmol). [Na (H ₂ O) ₂ ] _x MoO ₃ thin film was prepared according to the method of Example 1 except that the immersion time of the MoO ₃ thin film was 30 seconds. H ₂ O) ₂ ] _x MoO ₃ thin films were prepared. Further, in an aqueous solution prepared by dissolving [Na (H ₂ O) ₂ ] _x MoO ₃ thin film, 0.13 g (1.2 mmol) of butylammonium chloride (C ₄ H ₉ NH ₃ Cl) in 20 ml of distilled water. For 10 minutes. The thin film was taken out, washed with distilled water, and dried in air at 125 ° C. for about 15 minutes.

FIG. 12 shows X-ray diffraction patterns of the MoO ₃ thin film, [Na (H ₂ O) ₂ ] _x MoO ₃ thin film, and (C ₄ H ₉ NH ₃ ) _x MoO ₃ thin film. Even in the (C ₄ H ₉ NH ₃ ) _x MoO ₃ thin film, peaks indexed by (0k0) are observed, but these peaks are lower than [Na (H ₂ O) ₂ ] _x MoO _3. It can be seen that there is a shift to the angle side and the interlayer distance is increased. The interlayer distance obtained from FIG. 12C is 1.18 nm, which is an increase of 0.49 nm compared to the interlayer distance of MoO ₃ (0.69 nm). The spread of the interlayer distance corresponds to the case where butylammonium ions are intercalated, so that it was confirmed that a (C ₄ H ₉ NH ₃ ) _x MoO ₃ thin film was formed.

A gold comb electrode was deposited on the obtained (C ₄ H ₉ NH ₃ ) _x MoO ₃ thin film to produce a sensor element. The electric resistance value measured by the direct current two-terminal method was 5.6 MΩ at room temperature. The sensor characteristics of the (C ₄ H ₉ NH ₃ ) _x MoO ₃ thin film sensor with respect to formaldehyde gas were evaluated by changes in the electric resistance value. The (C ₄ H ₉ NH ₃ ) _x MoO ₃ thin film sensor responded by increasing the resistance value with respect to formaldehyde gas as in the case of the PPy _x MoO ₃ thin film sensor.

Comparative Example 1
An attempt was made to produce a PPy _x MoO ₃ thin film according to the method of Example 1 except that the substrate used for producing the MoO ₃ thin film was made of MgO (100) single crystal and the film formation time was 30 minutes. It was. FIG. 13 shows an X-ray diffraction pattern of the MoO ₃ thin film. The observed diffraction peaks are all due to the MoO ₃ phase, and a MoO ₃ single-phase film is obtained. However, since diffraction peaks other than (0k0) are observed, the MoO ₃ thin film has a polycrystalline structure and orientation is not sufficient. In the SEM photograph shown in FIG. 14, it can be seen that MoO ₃ particles having a diameter of 500 to 900 nm and a thickness of 150 to 250 nm are stacked and grown. It can be seen that the well-developed surface of the plate-like crystal grains is not necessarily parallel to the substrate surface and the b-axis orientation is not sufficient. Attempts were made to intercalate hydrated sodium ions into the MoO ₃ thin film having such a fine structure, and most of the film was peeled off.

  As described above in detail, the present invention relates to an electrically conductive organic-inorganic hybrid thin film and a method for producing the same, and according to the present invention, an intercalation type using an inorganic compound as a host and an organic compound as a guest. The organic-inorganic hybrid thin film can be obtained. The obtained organic-inorganic hybrid thin film can be used as an electronic device material due to its electrical conductivity. In particular, the electrically conductive organic-inorganic hybrid thin film obtained by the method of the present invention can be easily manufactured by the CVD method and the immersion method in a solution, so that it can be integrated, for example, as a sensor for various uses. It can be used suitably. A conductive member and a sensor member including the organic-inorganic hybrid thin film as a constituent element can be provided. INDUSTRIAL APPLICABILITY The present invention is useful for providing new materials and new technologies that enable the production of next-generation high-performance electronic devices in these technical fields.

It is a figure which shows the schematic diagram of a molybdenum trioxide crystal structure. 2 is a diagram showing an X-ray diffraction pattern of a MoO ₃ thin film shown in Example 1. FIG. ₃ is a view showing a scanning electron micrograph of the surface state of the MoO ₃ thin film shown in Example 1. FIG. Illustrates shown in Example 1 (a) [Na (H ₂ O) _{2] x} MoO ₃ thin film, and (b) PPy _x MoO ₃ thin film X-ray diffraction pattern. It is a figure which shows the sensor characteristic with respect to formaldehyde gas of the thin film sensor shown in Example 1. FIG. Formaldehyde (Formaldehyde), acetaldehyde, chloroform (Chloroform), methanol (Ethanol), acetone (acetone), toluene (Toluene) of 1000 ppm concentration at room temperature of the thin film sensor shown in Example 1. It is a figure which shows the sensor sensitivity with respect to various VOC gas of benzene (Benzene). Shown in Example 2 (a) MoO ₃ film is a diagram showing a (b) [Na (H ₂ O) _{2] x} MoO ₃ thin film, and (c) PPy _x MoO ₃ thin film X-ray diffraction pattern. FIG. 6 is a diagram showing a pole figure of the MoO ₃ thin film shown in Example 2. 6 is a diagram illustrating β scan of the MoO ₃ thin film shown in Example 2. FIG. Is a diagram showing the sensor characteristics with respect to the formaldehyde gas PPy _x MoO ₃ thin film sensor shown in Example 2. Shown in Example ₃ (a) MoO 3 film is a diagram showing a (b) [Na (H ₂ O) _{2] x} MoO ₃ thin film, and (c) PPy _x MoO ₃ thin film X-ray diffraction pattern. X-ray diffraction patterns of (a) MoO ₃ thin film, (b) [Na (H ₂ O) ₂ ] _x MoO ₃ thin film, and (c) (C ₄ H ₉ NH ₃ ) _x MoO ₃ thin film shown in Example 4 FIG. 6 is a diagram showing an X-ray diffraction pattern of a MoO ₃ thin film shown in Comparative Example 1. FIG. 6 is a view showing a scanning electron micrograph of the surface state of the MoO ₃ thin film shown in Comparative Example 1. FIG.

Claims (8)

A conductive organic-inorganic hybrid thin film in which a highly oriented thin film of an inorganic compound having a layered structure is intercalated with a hydrated alkali metal ion and further substituted with an organic compound ,
The inorganic compound having the layered structure is mainly composed of molybdenum oxide, and the highly oriented thin film is b-axis oriented on a metal oxide single crystal substrate having a lattice constant similar to that of the inorganic compound. An organic-inorganic hybrid thin film characterized by being a highly oriented thin film.   The organic-inorganic hybrid thin film according to claim 1, wherein the organic compound is a conductive polymer.   The organic-inorganic hybrid thin film according to claim 1, wherein the organic compound is an organic ion. A method for producing a conductive organic-inorganic hybrid thin film,
(1) A highly oriented thin film of an inorganic compound is produced by producing a highly oriented thin film of an inorganic compound that is b-axis oriented on a metal oxide single crystal substrate having a lattice constant similar to that of an inorganic compound having a layered structure . (2) intercalated hydrated alkali metal ions in the high orientation film, replacing the (3) which an organic compound consists step, an inorganic compound having the layered structure, molybdenum oxide as a main component Is,
A method for producing an organic-inorganic hybrid thin film. 5. The method for producing an organic-inorganic hybrid thin film according to claim 4 , wherein the organic compound is a conductive polymer. The method for producing an organic-inorganic hybrid thin film according to claim 4 , wherein the organic compound is a cationic organic compound. Conductive member, characterized in that it comprises as a component an organic-inorganic hybrid thin film according to any one of claims 1 to 3. Chemical sensor member, characterized in that it comprises as a component an organic-inorganic hybrid thin film according to any one of claims 1 to 3.