JP2627619B2 - Organic amorphous film preparation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention uses an organic substance that changes its color, molecular structure, crystal structure, electronic state, bonding state, polarity, etc. by absorbing the light when irradiated. The present invention also relates to a method for producing a thin film in which the vacuum-deposited film becomes a glassy amorphous thin film.

[Prior Art] As a method for preparing an organic thin film, there are a spatter method, a vacuum evaporation method, a spin coating method, a dipping method, a Lagmuir-Blodgett (LB) method and the like.

Among them, the vacuum deposition method does not use a solvent or a dispersant, etc.
Since a thin film can be manufactured by a dry (dry) process, the film thickness can be easily controlled, and a multilayer thin film or a mixed thin film in which several kinds of organic substances are mixed at an arbitrary ratio can be manufactured.

In addition, since a sublimation purification process is inevitably added during the deposition, a thin film made of a pure substance containing no impurities can be obtained.

However, since it has to be heated to near the boiling point or sublimation temperature under reduced pressure, some organic substances are thermally decomposed. Further, depending on the type of organic substance, there are many substances in which a thin film produced by a vacuum deposition method contains microcrystals or becomes a polycrystalline film, and only an opaque organic thin film can be obtained. Furthermore, even in the case of a glassy amorphous thin film in a vacuum, crystallization occurs and progresses when exposed to air, and some organic substances become cloudy and opaque.

Organic substances that show photochromism by changing the molecular structure by light irradiation, for example, spiropyrans and fulgides (generic term for bis-methylene-succinic anhydride), typical organic compounds that show cis-trans isomerization, for example, Most of the deposited films of azobenzenes and stilbenes become microcrystalline and opaque thin films, and a glassy amorphous thin film can be formed using any of the thin film forming methods described above. It was difficult.

[Problems to be solved by the invention]

The present invention relates to a method for producing an organic thin film by a vacuum evaporation method of an organic substance.In the conventional technique, a glassy amorphous thin film is produced even for an organic substance which cannot obtain a glassy amorphous thin film due to crystallization, oxidation, and decomposition. It is an object of the present invention to provide a vacuum deposition method capable of performing the above.

[Means for solving the problem]

In general, the present invention relates to a method for forming an organic amorphous film. In a method for forming a thin film by a vacuum evaporation method, an organic material selected from the group consisting of stilbenes, azobenzenes, and fulgides is vacuum-evaporated. It is characterized in that an amorphous film is obtained by vapor deposition while irradiating light from a light source disposed outside the tank.

According to the present invention, when light is irradiated, an organic substance that changes its color, molecular structure, crystal structure, electronic state, bonding state, polarity, etc. by absorbing the light is subjected to vacuum deposition while irradiating the light, and a glassy non-glass The main feature is to obtain a crystalline thin film.

In the conventional vacuum deposition method, almost all organic substances have become cloudy due to crystallization. However, by using the present invention, by irradiating light absorbed by the organic substance, the color of the organic substance,
Since the molecular structure, the crystal structure, the electronic state, the bonding state, the polarity, and the like change, the crystal structure is changed, and an organic amorphous thin film that cannot be obtained by the conventional technique can be obtained.

In addition, the amorphous thin film has a free volume around the compound molecule in the amorphous thin film as compared with the crystal structure of the compound.

Therefore, the quantum yields of stilbenes and azobenzenes, which are typical compounds showing a molecular structure change and a cis-trans isomer change by light irradiation, are significantly increased in an amorphous thin film compared to a crystalline thin film.

Furthermore, by light irradiation, with molecular motion (E)
(Z) The quantum yield of typical isomerized compounds, fulgides, increases dramatically in an amorphous thin film compared to a crystalline thin film.

Light irradiation on the organic substance may be performed on the organic substance in any state in the vacuum evaporation apparatus. For example, it may be performed for an organic substance in a gaseous phase state, an organic substance on a heating boat during vapor deposition, and an organic substance on a substrate during vapor deposition and forming a thin film. In addition, the light irradiation may use a transparent substrate and irradiate the organic substance with light through the substrate. Further, in the case where several kinds of organic substances are vapor-deposited simultaneously by the production method according to the present invention, it is preferable to perform vapor deposition while irradiating at least one kind of organic substance with light.

The light used in the method of the present invention is not limited to visible light, but if the energy is high, organic substances may be decomposed.
Generally, it is desirable to use a light source that enters the infrared region from the ultraviolet region.

Examples of the compound used in the present invention, whose color, molecular structure, crystal structure, electronic state, bonding state, polarity and the like are changed by light irradiation, include fulgides, stilbenes, and azobenzenes.

Examples of the stilbenes and azobenzenes include organic compounds having a basic structural formula shown below.

(In the above formulas, R _{6 to} R ₉ are the same or different, and hydrogen,
(Indicating lower alkyl group, lower alkoxy group, nitro group, hydroxyl group, halogen, amino group, mono- or di-substituted amino group) Examples of fulgides include compounds having the following basic structural formula.

(In the formula, R _{10 to} R ₁₃ are the same or different and each represent hydrogen or a substituent, but at least one is a group having an aromatic ring.) [Examples] Hereinafter, the present invention will be more specifically described by Examples. Although described, the present invention is not limited to these examples.

FIG. 1 is a schematic sectional view of an apparatus for producing an organic amorphous film used in Example 1. In FIG. 1, reference numeral 11 is a bell jewel, 12 is a substrate, 13 is an ultraviolet light, 14 is an ultra-high pressure mercury lamp, 15 is a slit, 16 is a sample, 17 is a heating boat, 18 is a heating temperature control device, 19 is a quartz window, 20 means a colored glass filter.

Embodiment 2 FIG. 2 is a schematic sectional view of an organic amorphous thin film deposition apparatus used in one example of the method of the present invention. In FIG. 2, reference numeral 51 indicates
500W ultra-high pressure mercury lamp, 52 is a light reflecting mirror, 53 is a glass bell jer that transmits 365nm ultraviolet light, 54 is a quartz substrate,
55 is a sample, 56 is a heating boat, 57 is a heating temperature controller, 58
Indicates a light beam, and 59 indicates a color glass filter. Using a transparent quartz substrate as the substrate, light was irradiated from the back of the substrate, and the thin film being deposited on the quartz substrate, the sample in the vapor phase during vapor deposition, and the sample on the heating boat were irradiated with light. .

Embodiment 3 FIG. 3 is a schematic sectional view of an organic amorphous thin film deposition apparatus used in one example of the method of the present invention. In FIG. 3, reference numeral 61 denotes
500W ultra high pressure mercury lamp, 62 is a light reflecting mirror, 63 is a glass bell jersey that transmits 365nm ultraviolet light, 64 is a silicon (Si) substrate, 65 is a sample, 66 is a heating boat, 67 is a heating temperature control device, 68 Indicates a light beam, and 69 indicates a colored glass filter. In this case, since the opaque Si substrate was used as the substrate, light was irradiated from the substrate side, and the thin film being deposited on the Si substrate was irradiated with ultraviolet light.

Example 4 FIG. 4 is a schematic sectional view of an organic amorphous thin film deposition apparatus used in one example of the method of the present invention. In FIG. 4, reference numeral 71 indicates
500W ultra-high pressure mercury lamp, 73 is a glass bell jar that transmits 365nm ultraviolet light, 74 is a substrate, 75 is a sample, 76 is a heating boat, 77 is a heating temperature control device, 78 is a light beam, and 79 is a color glass filter I do.

Example 5 The apparatus shown in FIG. 1 was used. The organic sample used was a compound that undergoes cis-trans isomerization upon light irradiation,
-Nitro-4'-dimethylaminostilbene (abbreviation: NDA
SB). The structural change is shown by the following formula.

The heating boat shown in FIG. 1 is heated to 80 ° C. by the heating temperature control device 18 in FIG. 1, the degree of vacuum is 1 × 10 ⁻⁴ Torr, and the ultraviolet light source is a super high pressure mercury lamp of 500 W, which emits 360 nm bright lines. Vacuum evaporation was performed while irradiating ultraviolet light to NDASB in a gas phase state during evaporation. As shown in the above formula, NDASB changes its molecular structure by cis-trans isomerism when irradiated with ultraviolet light. When NDASB was deposited by a conventional vacuum deposition method, only an opaque thin film was obtained by crystallization. However, as shown in FIG. 1 according to the method of the present invention, when vapor deposition is performed while irradiating ultraviolet light, the structure of NDASB molecules changes from a cis form to a trans form, and the crystal structure also changes. An organic amorphous thin film was obtained.

FIG. 5 is an absorption spectrum diagram of the NDASB thin film obtained by the conventional method (broken line a) and the method according to the present invention (solid line b) [the horizontal axis represents wavelength (nm), and the vertical axis represents optical density (Optical Densit).
y, OD)]. Both substrates used transparent quartz substrates. Since the NDASB film obtained by the conventional method became cloudy and opaque due to crystallization, an increase in optical density (OD) due to light scattering was observed over the entire measurement wavelength range. On the other hand, the NDASB thin film obtained by the method of the present invention did not absorb at all in the region other than the absorption by the cis-form, and was completely transparent. In addition, absorption by the cis-form is reduced by returning NDASB to the trans-form by heating or irradiation with visible light.
As shown in the figure and the solid line c, a glassy NDASB vapor deposition film was obtained for the first time. When this film was irradiated with ultraviolet light again, it developed a color, and it was possible to obtain, for the first time, an NDASB amorphous thin film showing a reversible cis-trans isomer change while being amorphous.

Example 6 The apparatus shown in FIG. 2 was used. The deposition sample is Example 5.
In the same manner as in Example 5, NDASB was used, and various conditions were the same as in Example 5. Thus, even if the transparent substrate was directly irradiated with light, the transparent glass large amorphous thin film of NDASB obtained in Example 5 could be obtained.

Example 7 The apparatus shown in FIG. 3 was used. The deposition sample is Example 5.
In the same manner as in Example 5, NDASB was used, and various conditions were the same as in Example 5. Thus, even when the substrate was irradiated with light from the side of vapor deposition using the opaque substrate, the transparent glassy amorphous thin film of NDASB obtained in Example 5 could be obtained.

Example 8 The apparatus shown in FIG. 4 was used. As the sample, NDASB was used as in Example 5. During deposition, NDASB once melts from a solid on a heated boat, turns into a liquid state, and then evaporates. In Example 8, NDASB in a liquid state on the heating boat was irradiated with ultraviolet light, and vacuum deposition was performed under the same conditions as in Example 5. Thus, even when the sample on the heating boat was directly irradiated with light, the transparent glassy amorphous thin film of NDASB obtained in Example 5 could be obtained.

Example 9 The apparatus shown in FIG. 1 was used. The organic sample used is a representative compound, azobenzene, which undergoes cis-trans isomerization upon light irradiation. The structural change is shown by the following formula.

The heating boat shown in FIG. 1 is heated to 80 ° C. by the heating temperature control device 18 in FIG. 1, the degree of vacuum is 1 × 10 ⁻⁴ Torr, and the ultraviolet light source is a super high pressure mercury lamp of 500 W, which emits 360 nm bright lines. Vacuum evaporation was performed while irradiating ultraviolet light to azobenzene in a gas phase state during evaporation. As shown in the above formula, azobenzene changes its molecular structure by cis-trans isomerism when irradiated with ultraviolet light. When this azobenzene was deposited by a usual vacuum deposition method, only an opaque thin film was obtained due to crystallization.

However, as shown in FIG. 1 according to the method of the present invention, when vapor deposition is performed while irradiating ultraviolet light, the structure of azobenzene molecules changes from a cis-form to a trans-form, and the crystal structure also changes. An organic amorphous thin film was obtained.

FIG. 6 is an absorption spectrum diagram of an azobenzene thin film obtained by the conventional method (broken line a) and the method according to the present invention (solid line b) [the horizontal axis is wavelength (nm), and the vertical axis is optical density (Optical Depth).
nsity, OD)]. Both substrates used transparent quartz substrates.

Since the azobenzene thin film obtained by the conventional method became cloudy and opaque due to crystallization, an increase in optical density (OD) due to light scattering was observed over the entire measurement wavelength range.

On the other hand, the azobenzene thin film obtained by the method according to the present invention did not absorb at all except in the region other than the absorption by the cis body, and was completely transparent. In addition, absorption by the cis-form was also reduced by returning azobenzene to the trans-form by heating or irradiation with visible light, and a glassy azobenzene-deposited film could be obtained for the first time as shown by the solid line c in FIG. When this film was irradiated with ultraviolet light again, it developed a color, and it was possible to obtain, for the first time, an azobenzene amorphous thin film showing a reversible cis-trans isomer change while being amorphous.

Example 10 The apparatus shown in FIG. 2 was used. The deposition sample is Example 9
Azobenzene was used in the same manner as in Example 9 and the conditions were the same as in Example 9. Thus, even if the transparent substrate was directly irradiated with light, a transparent glassy amorphous thin film of azobenzene obtained in Example 9 could be obtained.

Example 11 The apparatus shown in FIG. 3 was used. The deposition sample is Example 9
Azobenzene was used in the same manner as in Example 9 and the conditions were the same as in Example 9. Thus, even when the substrate was irradiated with light from the side to be vapor-deposited using the opaque substrate, the transparent glassy amorphous thin film of azobenzene obtained in Example 9 could be obtained.

Example 12 The apparatus shown in FIG. 4 was used. As the sample, azobenzene was used as in Example 9. When depositing azobenzene, it is first melted from a solid on a heating boat, becomes a liquid state, and then evaporates. In Example 12, azobenzene in a liquid state on the heating boat was irradiated with ultraviolet light, and vacuum deposition was performed under the same conditions as in Example 9. Thus, even when the sample of the heating boat was directly irradiated with light, the transparent glassy amorphous thin film of azobenzene obtained in Example 9 could be obtained.

Example 13 The apparatus shown in FIG. 1 was used. As the organic substance, (E) -α-2,5-dimethyl-3-furylethylidene (7,7-dimethylmethylene) succinic anhydride (abbreviation: furylflugide) whose molecular structure changes upon irradiation with ultraviolet light was used. The structural change is shown by the following formula.

The heating boat shown in FIG. 1 is heated to 200 ° C. by the heating temperature control device 18 in FIG. 1, the degree of vacuum is 1 × 10 ⁻⁴ Torr, and the ultraviolet light source is a super high pressure mercury lamp of 500 W, which emits 360 nm bright lines. Vacuum deposition was performed while irradiating ultraviolet light to futilfurgide in a gas phase state during the deposition. As shown in the above formula, furrfulgide changes its molecular structure when irradiated with ultraviolet light. When frillfulgide was deposited by a usual vacuum deposition method, only an opaque thin film could be obtained by crystallization. However, as shown in the structure of FIG. 1 according to the method of the present invention, when vapor deposition is performed while irradiating ultraviolet light, the structure of the furylflugide molecule changes, and the crystal structure also changes.
A glassy organic amorphous thin film of furfurflugide was obtained for the first time.

FIG. 7 is an absorption spectrum diagram of a frillflugide thin film obtained by the conventional method (broken line a) and the method of the present invention (solid line b) [the horizontal axis represents wavelength (nm), and the vertical axis represents optical density (Optical density).
Density, OD). Both substrates used transparent quartz substrates. Since the frillfulgide thin film obtained by the conventional method becomes cloudy and opaque due to crystallization, an increase in optical density (OD) due to light scattering was observed over the entire measurement wavelength range.

On the other hand, the furyl fulgide thin film obtained by the method of the present invention had no absorption except in the region other than the absorption by the (Z) body, and was completely transparent. Further, the absorption by the (Z) body is also reduced by returning the firfulgide to the (E) body by heating or irradiation with visible light, and as shown in FIG. 7, a solid line c, a glassy frillfulgide deposited film can be obtained for the first time. Was. When this film was irradiated with ultraviolet light again, a color was formed, and a frillfulgide amorphous thin film showing a reversible (E) (Z) change in an amorphous state could be obtained for the first time.

Example 14 The apparatus shown in FIG. 2 was used. The vapor deposition sample is Example 13.
In the same manner as in Example 2, furylfurgide was used, and the conditions were the same as in Example 13. Thus, even if the transparent substrate was directly irradiated with light, the transparent glassy amorphous thin film of frillfulgide obtained in Example 13 could be obtained.

Example 15 The apparatus shown in FIG. 3 was used. The vapor deposition sample is Example 13.
In the same manner as in Example 2, furylfurgide was used, and the conditions were the same as in Example 13. Thus, even when the substrate was irradiated with light from the side of vapor deposition using the opaque substrate, the transparent glassy amorphous thin film of frillfulgide obtained in Example 13 could be obtained.

Example 16 The apparatus shown in FIG. 4 was used. As a sample, frillflugide was used as in Example 13. During vapor deposition, frillfulgide is once melted from a solid on a heating boat, turned into a liquid state, and then evaporated. In Example 16, the liquid state furyl fulgide on the heating boat was irradiated with ultraviolet light, and vacuum deposition was performed under the same conditions as in Example 13. Thus, even when the sample on the heating boat was directly irradiated with light, the transparent glassy amorphous thin film of frillfulgide obtained in Example 13 could be obtained.

〔The invention's effect〕

As described above, by using the method for producing an organic amorphous film of the present invention, even a compound in which it was difficult to obtain an amorphous thin film by the conventional method for producing a thin film can be used as a glassy transparent non-crystalline film. A crystalline film can now be formed. Therefore, compounds that have conventionally been impossible to vapor-deposit can now be vapor-deposited. At present, thin films can be obtained only by a wet method, and organic substances can be thinned by a dry method. By using this method, a great effect can be expected for dry thinning of a resist material or the like.

Further, since the organic substance is thinned by the light irradiation while being in an excited state, a function that cannot be realized by a thin film manufactured by a conventional method, for example, an organic solar cell can be manufactured.

Furthermore, as shown in the examples, the conventional method crystallizes and becomes cloudy, and the frillfulgide film which becomes an opaque thin film, further the NDASB film and the azobenzene film become amorphous according to the present invention, Moreover, while being transparent and amorphous
It can be used as a rewritable optical disk medium because it efficiently shows a reversible change by ultraviolet light or visible light (or heating), that is, coloring and decoloring of color, so-called photochromism or cis-trans isomerization change. There is no need to use a molecular dispersion medium, etc.
An SN ratio can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, FIG. 2, FIG. 3, and FIG. 4 are schematic sectional views of an example of an organic amorphous thin film producing apparatus used in the present invention, FIG.
6 and 7 are absorption spectrum diagrams of 18 examples of the vacuum deposited thin film of the present invention. 11: Perzier, 12, 64: Substrate, 13: Ultraviolet ray, 14, 51, 6
1, 71: 500W ultra-high pressure mercury lamp, 15: slit, 16, 55, 65, 7
5: Sample, 17, 56, 66, 76: Heated boat, 18, 57, 67, 77:
Heating temperature control device, 19: quartz window, 52, 62: light reflection mirror,
53, 63, 73: glass bell jersey, 54, 74: quartz substrate, 5
8, 68, 78: rays, 20, 59, 69, 79: colored glass filters.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Nobuhiro Funakoshi No. 162, Shirane, Shikata, Tokai-mura, Naka-gun, Ibaraki Pref. JP, A) JP-A-62-274063 (JP, A)

Claims (6)

(57) [Claims] An organic material selected from the group consisting of stilbenes, azobenzenes, and fulgides is vapor-deposited while irradiating light from a light source disposed outside a vacuum chamber to an amorphous material. A method for producing an organic amorphous film, characterized by obtaining a porous film. 2. The method for producing an organic amorphous film according to claim 1, wherein said light irradiation is performed by irradiating an organic substance in a gas phase state during vapor deposition. 3. The method for producing an organic amorphous material according to claim 1, wherein the light irradiation is performed by irradiating the substrate being vapor-deposited and irradiating the organic thin film being deposited. 4. The method according to claim 1, wherein the light irradiation is performed by light passing through a substrate being deposited.
2. The method for producing an organic amorphous film according to claim 1, wherein the method is performed while irradiating both the deposited organic thin film and the organic substance in a gas phase. 5. The method for producing an organic amorphous film according to claim 1, wherein said light irradiation is performed by irradiating an organic substance on a heating boat during vapor deposition with light. 6. The method according to claim 1, wherein, in the case of depositing several kinds of organic substances simultaneously, the deposition is performed while irradiating at least one kind of organic substances with light. 3. The method for producing an organic amorphous film according to item 1.