JP5141342B2 - Protective film and method for producing protective film - Google Patents

Description

  The present invention relates to an improvement in a protective film for protecting a semiconductor device, particularly an organic functional element, and a manufacturing method thereof.

  In an organic functional element typified by an organic EL, an organic solar cell, an organic light receiving element, etc., deterioration of element characteristics due to intrusion of moisture and oxygen in the atmosphere into the element is a problem. In order to suppress the deterioration of the element characteristics, it is effective to seal the organic functional element in a case with high airtightness. However, if the airtightness is increased, the case becomes large, resulting in the entire organic functional element as a whole. There is a problem of increasing the size of the. Further, such sealing in an airtight case has a problem in that it cannot be applied to a flexible element utilizing the flexibility of the organic material constituting the organic functional element. Therefore, it is desired to cover the organic functional element with a protective film as a sealing means for solving the above-described problems.

  As described above, a protective film for sealing an organic functional element, particularly an element having a function of emitting or absorbing light, such as an organic EL, an organic solar battery, and an organic light receiving element, is transparent to visible light. There is a need. For this reason, inorganic films, such as a silicon oxide film, an aluminum oxide film, and a nitric oxide film, and organic films, such as a polyparaxylylene film, are considered as a protective film.

  By the way, generally, the inorganic film as described above is often formed by a plasma CVD method or a thermal CVD method. And in order to obtain a high-quality inorganic sealing film, it is necessary to reduce the hydrogen content in the sealing film. Therefore, the hydrogen content in the sealing film is increased by increasing the substrate temperature during film formation. Decrease.

  However, the organic functional material to be protected generally has low heat resistance. For this reason, when forming an inorganic sealing protective film on an organic functional element, there exists a problem that an element may receive the damage by temperature. In addition, since an inorganic film having a low hydrogen content tends to have a large film stress, there is a problem in terms of coverage, such as an interface between an organic functional element and a protective film made of an inorganic film being peeled off.

  In contrast, a polyparaxylylene film that is an organic film is formed on a target by thermally polymerizing a xylene monomer. Since this organic film can be formed at a low temperature, it is considered suitable as a sealing protective film for an organic functional element in that the damage to the organic functional element due to the temperature at the time of film formation is small.

  However, the above-mentioned polyparaxylylene film is chemically very stable. However, since it is stable, there is a problem that adhesion with an organic functional element may be impaired, and interface peeling may occur. .

On the other hand, Patent Document 1 discloses a method of producing a protective film with a film obtained by blending polysilane, which is a silicon polymer, and a polymer such as polyvinyl or polyimide. Thus, according to the technique disclosed in Patent Document 1, a thin protective barrier can be formed on the surface by performing UV ozone treatment on the polymer blend film.
Japanese Patent Laid-Open No. 10-72551

  However, in the technique disclosed in Patent Document 1, it is necessary to blend while controlling the addition concentration of two or more kinds of polymers, and there is a problem that it is not easy to control the addition concentration. In addition, there is a problem that there are many restrictions such as selection of a solvent in which two or more kinds of polymers are soluble.

The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a protective film that is excellent in blocking and adhering to outside air and strong against external force.
Another object of the present invention is to provide a method for producing a protective film that is excellent in outside air blocking properties and adhesion and is strong against external forces.

In order to achieve the above object, the present invention employs the following configuration.
That is, the protective film of the present invention is a protective film that protects the organic functional element formed on the substrate, and the protective film forms an interface with the organic functional element on the organic functional element side. a polysilane compound layer consisting mainly of polysilane compound provided, and the organic functional device on the opposite side, a siloxane compound layer mainly the provided siloxane compound contiguous with the polysilane compound layer, is composed of characterized in that that.
Moreover, the protective film of this invention may have a layer in which both the polysilane compound and the siloxane compound are included between the polysilane compound layer and the siloxane compound layer.

According to the protective film of the present invention, the structure includes a polysilane compound layer mainly composed of a polysilane compound and a siloxane compound layer mainly composed of a siloxane compound. Since the polysilane compound layer does not transmit oxygen molecules, and the siloxane compound layer does not transmit water molecules, it is possible to provide a protective film having excellent outside air blocking properties. Thereby, deterioration of element characteristics of the organic functional element due to moisture and oxygen in the air can be prevented.
Moreover, since the flexible polysilane compound layer forms an interface with the organic functional element, the adhesion between the organic functional element and the protective film is excellent. Thereby, peeling at the interface between the organic functional element and the protective film can be suppressed. Furthermore, since the siloxane compound layer having film strength is provided on the side opposite to the organic functional element, a protective film that is strong against external force can be obtained. Thereby, damage to the organic functional element can be prevented from mechanical external force.

  The method for producing a protective film of the present invention is a method for producing a protective film for protecting an organic functional element formed on a substrate, wherein the organic functional element is coated with a polysilane compound to form a polysilane compound layer; And irradiating the surface of the polysilane compound layer with ultraviolet rays to form a siloxane compound from the polysilane compound to form a siloxane compound layer.

  According to the method for producing a protective film of the present invention, after the polysilane compound layer is formed, the surface of the polysilane compound layer is irradiated with ultraviolet rays. Thus, a siloxane compound layer can be formed by generating a siloxane compound from a polysilane compound by a simple method of irradiating ultraviolet rays. Therefore, it is possible to provide a method for manufacturing a protective film capable of easily forming a protective film having excellent characteristics as described above.

In the method for producing a protective film of the present invention, it is preferable that the wavelength of the ultraviolet light is set to a light absorption maximum wavelength resulting from the Si—Si bond of the polysilane compound.
In this way, by setting the wavelength of the ultraviolet light around the absorption maximum wavelength derived from the Si—Si bond of the polysilane compound, the irradiated ultraviolet light hardly transmits the polysilane compound. Thereby, the ultraviolet exposure to an organic functional element can be suppressed. Therefore, it is possible to prevent the organic functional element from being deteriorated by the irradiation of ultraviolet rays.

Furthermore, in the method for producing a protective film of the present invention, ultraviolet irradiation conditions corresponding to the film thickness of the siloxane compound layer are determined from a change in light absorption intensity of the polysilane compound layer with respect to ultraviolet irradiation, and the irradiation conditions are used to determine the irradiation conditions. It is preferable to control the thickness of the siloxane compound layer.
Furthermore, in the method for producing a protective film of the present invention, the irradiation condition of ultraviolet light corresponding to the film thickness of the siloxane compound layer is determined from the change in emission intensity of the polysilane compound layer with respect to ultraviolet irradiation, and the irradiation condition is used to determine the irradiation condition. The film thickness of the siloxane compound layer may be controlled.

  As described above, the irradiation conditions of ultraviolet rays are determined in advance using the light absorption intensity change and the emission intensity change with respect to the ultraviolet irradiation of the polysilane compound layer, and the film thickness of the siloxane compound layer is controlled using this irradiation condition. The film thickness ratio between the compound layer and the polysilane compound layer can be easily determined. Accordingly, it is possible to provide a method for manufacturing a protective film that can easily adjust the protective property for preventing damage to the element from a mechanical external force and the flexibility of the protective film itself.

As described above, according to the protection of the present invention, it is possible to provide a protective film that is excellent in blocking and adhering to the outside air and strong against external force.
Moreover, according to the method for producing a protective film of the present invention, it is possible to provide a method for producing a protective film that is excellent in the blocking and adhesion of outside air and is strong against external force.

  Hereinafter, an embodiment to which the present invention is applied will be described with reference to the drawings. The drawings referred to in the following description are for explaining a protective film according to an embodiment of the present invention. The size, thickness, dimensions, etc. of each part shown in the figure are the dimensions of each part in the actual protective film. The relationship may be different.

<Protective film>
First, the configuration of the protective film will be described as an embodiment of the present invention.
FIG. 1 is a schematic cross-sectional view showing a protective film according to an embodiment to which the present invention is applied. As shown in FIG. 1, the protective film 30 of the present embodiment is provided to protect the organic functional element 20 formed on the substrate 10, and is schematically configured from a polysilane compound layer 31 and a siloxane compound layer 32. Has been.

  The material of the substrate 10 is not particularly limited, and can be appropriately selected according to required characteristics. In the case where the substrate 10 is not bent, for example, an inorganic material such as silicon or glass, a metal such as gold, silver, copper, or iron can be used. On the other hand, when the substrate 10 is required to be flexible, acrylic resin, polyester resin, polycarbonate resin, styrene resin, vinyl chloride resin, epoxy resin, fluororesin, olefin resin, polyimide resin, cellulose resin, polyethylene Polymer-based organic materials such as plastic resins and functional norbornene resins, and thin metal materials such as stainless steel can be applied. Can also be used.

  As shown in FIG. 1, the organic functional element 20 is formed on a base material 10 and is composed of an organic polymer material or an organic low-molecular material such as an organic semiconductor and a conductive polymer. Although this organic functional element 20 is not specifically limited, An organic electroluminescent (electroluminescence: EL) display element, an organic solar cell, an organic light receiving element, etc. can be illustrated.

  As shown in FIG. 1, the protective film 30 has at least a polysilane compound layer 31 and a siloxane compound layer 32, the polysilane compound layer 31 is formed on the organic functional element 20 side, and the siloxane compound layer 32 is It is formed on the side opposite to the organic functional element 20.

  The polysilane compound layer 31 is mainly composed of a polysilane compound. This polysilane compound is a polymer compound represented by the following general formula (1) in which -Si-Si- bonds are repeated.

式中、ｎは重合度であり、Ｒ_１、Ｒ_２は、アルキル基（ａｌｋｙｌ ｇｒｏｕｐ）やアリール基（ａｒｙｌ ｇｒｏｕｐ）などの有機官能基である。
有機官能基Ｒ_１、Ｒ_２がアルキル基の場合には、Ｃ_ｍＨ_２ｍ＋１で表される。このｍの値は、１〜１０の範囲であることが好ましい。ｍの値が１０を超えると、有機官能基Ｒ_１、Ｒ_２が嵩高くなり、ポリシラン化合物層３１の膜密度が低下するため好ましくない。
また、ポリシラン化合物の重合度ｎは、１０以上であり、好ましくは２０以上である。なお、重合度ｎが１０以下の場合には、オリゴシラン化合物という場合がある。

In the formula, n is the degree of polymerization, and R ₁ and R ₂ are organic functional groups such as an alkyl group and an aryl group.
When the organic functional groups R ₁ and R ₂ are alkyl groups, they are represented by C _m H _{2m + 1} . The value of m is preferably in the range of 1-10. If the value of m exceeds 10, the organic functional groups R ₁ and R ₂ become bulky and the film density of the polysilane compound layer 31 is lowered, which is not preferable.
The degree of polymerization n of the polysilane compound is 10 or more, preferably 20 or more. In addition, when polymerization degree n is 10 or less, it may be called an oligosilane compound.

  The siloxane compound layer 32 is mainly composed of a siloxane compound. This siloxane compound is a polymer compound represented by the following general formula (2) in which -Si-O- bonds are repeated.

式中、ｎは重合度であり、Ｒ_１、Ｒ_２は、アルキル基（ａｌｋｙｌ ｇｒｏｕｐ）やアリール基（ａｒｙｌ ｇｒｏｕｐ）などの有機官能基である。
有機官能基Ｒ_１、Ｒ_２がアルキル基の場合には、Ｃ_ｍＨ_２ｍ＋１で表される。このｍの値は、１〜１０の範囲であることが好ましい。ｍの値が１０を超えると、有機官能基Ｒ_１、Ｒ_２が嵩高くなり、シロキサン化合物層３２の膜密度が低下するため好ましくない。
また、シロキサン化合物の重合度ｎは、１０以上であり、好ましくは２０以上である。なお、重合度ｎが２０以上の場合には、ポリシロキサン化合物という場合がある。

In the formula, n is the degree of polymerization, and R ₁ and R ₂ are organic functional groups such as an alkyl group and an aryl group.
When the organic functional groups R ₁ and R ₂ are alkyl groups, they are represented by C _m H _{2m + 1} . The value of m is preferably in the range of 1-10. If the value of m exceeds 10, the organic functional groups R ₁ and R ₂ become bulky and the film density of the siloxane compound layer 32 is lowered, which is not preferable.
Moreover, the polymerization degree n of a siloxane compound is 10 or more, Preferably it is 20 or more. In addition, when polymerization degree n is 20 or more, it may be called a polysiloxane compound.

  In the protective film 30, the polysilane compound layer 31 is made of at least 50% by weight or more of a polysilane compound, and the siloxane compound layer 32 is made of at least 50% by weight or more of a siloxane compound. Further, a layer containing both the polysilane compound and the siloxane compound may be present between the polysilane compound layer 31 and the siloxane compound layer 32. Furthermore, the protective film 30 may or may not be observed at the boundary between the polysilane compound layer 31 and the siloxane compound layer 32 by cross-sectional microscope observation.

  Next, the role of each layer constituting the protective film 30 of this embodiment will be described. First, as shown in FIG. 1, the siloxane compound layer 32, which is a layer in contact with the atmosphere, plays a role of protecting the organic functional element 20 from mechanical external force and preventing intrusion of water molecules in the atmosphere. Thereby, deterioration of the element characteristic of the organic functional element 20 can be suppressed.

  On the other hand, oxygen molecules having a molecular diameter smaller than that of water molecules may pass through the siloxane compound layer 32. Therefore, the polysilane compound layer 31 serves to prevent oxygen molecules that have passed through the siloxane compound layer 32 from reaching the surface of the organic functional element 20. Furthermore, when ultraviolet light is present in normal use, polysilane molecules are bonded to oxygen molecules, whereby oxygen can be captured and deterioration of device characteristics of the organic functional device 20 can be prevented.

  Further, the total film thickness of the protective film 30 is preferably in the range of 0.2 μm to 10 μm, and more preferably in the range of 0.4 μm to 5 μm. If the thickness of the protective film 30 is less than 0.2 μm, the functions of the layers 31 and 32 are not exhibited because the film is too thin. Further, if the thickness of the protective film 30 exceeds 10 μm, it is not preferable because there is a high possibility that cracks will occur in the protective film 30 or film peeling due to an increase in film stress.

  Furthermore, the individual film thicknesses of the polysilane compound layer 31 and the siloxane compound layer 32 constituting the protective film 30 can be appropriately selected according to required characteristics. When importance is attached to protection against mechanical external force, the siloxane compound layer 32 may be thickened, and the protective film itself has flexibility such as sealing the organic functional element 20 formed on the flexible substrate 10. If desired, the siloxane compound layer 32 may be thinned. However, in order to sufficiently obtain the function of preventing intrusion of water molecules and oxygen molecules, it is desirable that both the siloxane compound layer 32 and the polysilane compound layer 31 have a thickness of 0.2 μm or more. Further, when the film thickness of the polysilane compound layer 32 is 0.2 μm or less, the amount of ultraviolet rays that pass through the polysilane compound layer 32 and reach the organic functional element 20 at the time of ultraviolet irradiation described later cannot be ignored. Considering this point, the thickness of the polysilane compound layer 32 is preferably 0.2 μm or more.

<Method for producing protective film>
Next, the manufacturing method of the protective film of this embodiment is demonstrated, referring FIG. The method for producing a protective film according to the present embodiment includes a step of coating the organic functional element 20 with a polysilane compound to form a polysilane compound layer 31, and irradiating the surface of the polysilane compound layer 31 with ultraviolet rays. And the step of forming the siloxane compound layer 32. Below, each process is demonstrated in detail.

(Silane compound layer formation process)
First, the process of forming the polysilane compound layer 31 by coating the organic functional element 20 with a polysilane compound, that is, the process of forming the polysilane compound layer will be described.
In the step of forming the polysilane compound layer, the polysilane compound is formed on the organic functional element 20 by using a dry method or a wet method. In this way, the polysilane compound layer 31 is formed.

Specific examples of the dry method include a vacuum deposition method, a sputtering method, a laser ablation method, a molecular beam deposition method (MBD method), a chemical vapor deposition method (CVD method), and the like.
Examples of the wet film forming method include a cast method, a spin coating method, a dipping method, a Langmuir-Blodgett method (LB method), and the like. The type of polysilane compound used and the solvent resistance of the organic functional element 20 It is possible to select as appropriate.

(Process for forming siloxane compound layer)
Next, a step of irradiating the surface of the polysilane compound layer 31 with ultraviolet rays to generate a siloxane compound from the polysilane compound to form the siloxane compound layer 32, that is, a step of forming the siloxane compound layer will be described.
In the step of forming the siloxane compound layer, the polysilane compound layer 31 is irradiated with ultraviolet rays for a certain period of time in an oxygen atmosphere, generally in the air. Thereby, the Si—Si bond of the polysilane compound is radically cut, and the generated silyl radical reacts with oxygen to be converted into a siloxane compound. In this way, the siloxane compound layer 32 is formed.

  The reaction by irradiation with ultraviolet rays as described above proceeds from the surface of the polysilane compound layer 31 to the inside with time. Therefore, by setting an appropriate ultraviolet irradiation time, ultraviolet wavelength, and ultraviolet intensity, the outer side of the protective film 30 is a siloxane compound layer 32 mainly composed of a siloxane compound, and the inner side of the protective film 30 (organic functional element). The protective film 30 that is the polysilane compound layer 31 mainly composed of a polysilane compound can be produced.

  By the way, the film thickness of the siloxane compound layer 32 formed as described above can be confirmed by photoelectron spectroscopy, infrared absorption, Rutherford backscattering, or the like. Further, a simpler method can be confirmed by a change in the ultraviolet absorption intensity or emission intensity of the polysilane compound of the protective film 30 with respect to the irradiation time of ultraviolet rays.

  The polysilane compound has unimodal ultraviolet absorption and emission derived from Si—Si bonds having a degree of polymerization of about 20 or more. It is known that if the Si-Si bond is broken and oxidized by ultraviolet irradiation, the intensity of ultraviolet absorption and emission is also reduced in proportion. Therefore, by grasping the relationship between these intensity changes and the film thickness of the siloxane compound layer 32, the time of the ultraviolet rays applied to the polysilane compound layer 31 necessary to form the siloxane compound layer 32 having a certain film thickness, Irradiation conditions such as intensity and wavelength can be determined.

(Determination method of irradiation conditions by light absorption intensity change)
Next, with respect to an example of polysilane compound conversion to siloxane compound, polydibutylsilane (in formula 1, R ₁ = R ₂ = C ₄ H ₉ ) is used as the polysilane compound, and siloxane compound formation when ultraviolet light is continuously irradiated is described. To do.
FIG. 2 is a graph showing the relationship between irradiation time and ultraviolet absorption intensity when polydibutylsilane is continuously irradiated with ultraviolet rays. Moreover, the continuous irradiation of the ultraviolet-ray to polybutylsilane was performed as follows. First, polydibutylsilane having a film thickness of 0.2 μm was formed on a quartz glass substrate by spin coating. Next, the polysilane compound layer mainly composed of polybutylsilane was continuously irradiated with ultraviolet light having a wavelength of 330 nm and 300 μW / cm ² , and the irradiation time t = 0 seconds, 300 seconds, and 600 seconds, The light absorption spectrum was measured.

The vertical axis | shaft of the graph shown in FIG. 2 is the light absorbency A, and is represented by following (3). As shown in FIG. 2, in the profile of the ultraviolet irradiation time t = 0 seconds, a light absorption peak is observed at a wavelength of 313 nm, which is absorption due to the Si—Si bond of the polysilane compound. Further, in the profile of the ultraviolet irradiation time t = 300 seconds, the light absorption peak at a wavelength of 313 nm decreased, and the absorbance value was about 80% compared with the profile of the irradiation time t = 0 seconds. This is because the Si—Si bond in the polysilane compound was broken and the subsequent oxidation was caused by ultraviolet irradiation.

  Thereafter, the polysilane compound layer was further irradiated with ultraviolet rays. In the profile of the irradiation time t = 600 seconds of ultraviolet rays, as shown in FIG. 2, the peak intensity of the absorbance is reduced to about 20% compared to the profile of the irradiation time t = 0 seconds, and the peak wavelength is shortened to 310 nm. I confirmed that it was shifting to the side. Such a shift of the peak wavelength to the short wavelength side is a phenomenon observed due to the shortened Si—Si bond length of the polysilane compound. That is, in most of the polysilane compound layer, the polysilane compound has been converted into a siloxane compound.

The above example can be generalized as described below.
First, assuming that light of intensity I changes in intensity by dI due to absorption of the polysilane compound while traveling through the polysilane compound layer for a small distance dx, the relationship of the following formula (4) is established. In the following formula (4), α ₁ is an absorption coefficient of the polysilane compound.

Next, the above equation (4) is integrated. Assuming that the light intensity at the distance x = 0 is I ₀ , the following equation (5) is obtained, which indicates that the light intensity I decreases exponentially with respect to the distance x.

By the way, in the above example, as shown in FIG. 2, the absorbance A decreased as the irradiation time of ultraviolet rays increased. When the film thickness of polydibutylsilane was set to d, the emission end of the above equation (5) Light intensity, that is, transmitted light intensity I = I ₀ exp (−α ₁ d) increases with time. Therefore, in this formula, it is shown that the film thickness d of polydibutylsilane decreases with time. That is, oxidation proceeds according to the absorption intensity distribution in the film thickness direction, and the part after the reaction becomes a siloxane compound.

Here, in the above formula (3), the absolute value of the transmittance can be expressed by I / I _0. Therefore, from the relationship between the above formula (5) and the above formula (3), it is shown in the following formula (6). As can be seen, the absorbance A and the film thickness x of the polysilane compound layer have a proportional relationship.

  Therefore, based on the absorbance of the polysilane compound layer at the time of ultraviolet irradiation time t = 0 seconds, the thickness of the polysilane compound layer and the siloxane compound layer is determined from the ratio of the decrease in the absorbance of the polysilane compound layer with respect to the ultraviolet irradiation time. Can be determined. That is, when the ratio between the siloxane compound layer and the polysilane compound layer is set to 2: 8, the ultraviolet irradiation time during which the absorbance of the polysilane compound layer decreases to 80% of the initial value is confirmed in advance. It is only necessary to irradiate the polysilane compound layer with ultraviolet rays using the irradiation conditions. When 5: 5 is desired, the irradiation time of the ultraviolet rays that decrease until the absorbance of the polysilane compound layer reaches 50% of the initial value is confirmed in advance. Thus, the polysilane compound layer may be irradiated with ultraviolet rays using this irradiation condition.

On the other hand, as the reaction from the polysilane compound to the siloxane compound proceeds, the absorbance of the siloxane compound layer also increases. However, the absorption maximum wavelength of the siloxane compound is shorter than 300 nm. When the absorption coefficient α ₂ of the absorption maximum wavelength of 300 nm or more of the siloxane compound is compared with the absorption coefficient α ₁ of the absorption maximum wavelength (> 300 nm) of the polysilane compound, α ₂ is much smaller than α ₁ . For this reason, the absorbance value of the siloxane compound at the absorption maximum wavelength of the polysilane compound can be ignored. Thereby, the film thickness of the siloxane compound layer can be determined using the amount of change in absorbance at the absorption maximum wavelength of the polysilane compound. Further, the film thickness ratio between the polysilane compound layer and the siloxane compound layer can be determined.

  In addition, the organic material which comprises an organic functional element also deteriorates by ultraviolet irradiation. However, by setting the wavelength of the ultraviolet ray irradiated to the polysilane compound layer to the vicinity of the absorption maximum wavelength derived from the Si-Si bond of the polysilane compound, the ultraviolet ray irradiated to the polysilane compound layer hardly transmits the polysilane compound layer. . Thereby, exposure of the ultraviolet-ray to an organic functional element can be suppressed. For example, as described above, in the example of polydibutylsilane shown in FIG. 2, it is desirable to set the wavelength of ultraviolet rays irradiated to the polysilane compound layer to about 310 to 315 nm.

(Determination method of irradiation conditions by emission intensity change)
Further, when the polysilane compound is irradiated with ultraviolet rays, light is emitted. Since the emission characteristics of the polysilane compound vary depending on the type of the polysilane compound, an emission spectrum having a wavelength characteristic of the polysilane compound to be used can be obtained. The film thickness of the siloxane compound layer can be determined in the same manner as the light absorption intensity change described above by measuring this emission spectrum and examining the change over time of the emission intensity with respect to ultraviolet irradiation.

The light emission intensity change can be generalized as described below, as in the case of the light absorption intensity change described above.
That is, as shown in the following formula (7), the emission intensity B and the film thickness x of the polysilane compound layer have a proportional relationship. In the following formula (7), β ₁ is a coefficient of emission intensity of the polysilane compound.

  Therefore, the film of the polysilane compound layer and the siloxane compound layer is determined from the ratio of the decrease in the light emission intensity of the polysilane compound layer with respect to the ultraviolet irradiation time, based on the light emission intensity of the polysilane compound layer when the ultraviolet irradiation time t = 0 seconds. The thickness can be determined. That is, when the ratio between the siloxane compound layer and the polysilane compound layer is set to 2: 8, the irradiation time of the ultraviolet ray that decreases until the emission intensity of the polysilane compound layer reaches 80% of the initial value is confirmed in advance. It is only necessary to irradiate the polysilane compound layer with ultraviolet rays using this irradiation condition. When 5: 5 is desired, the irradiation time of the ultraviolet rays that decrease until the emission intensity of the polysilane compound layer reaches 50% of the initial value is set in advance. It is only necessary to confirm and irradiate the polysilane compound layer with ultraviolet rays using this irradiation condition. Further, the irradiation amount of ultraviolet rays may be controlled by simultaneously measuring the emission intensity while irradiating the polysilane compound layer with ultraviolet rays.

  As described above, the protective film 30 of the present embodiment has excellent outside air blocking properties. In addition, the protective film 30 has excellent adhesion because the polysilane compound layer 31 made of a flexible polysilane polymer (polysilane compound) forms an interface with the organic functional element 20, and film peeling does not occur. Furthermore, the polysilane compound layer 31 is irradiated with ultraviolet rays to form the siloxane compound layer 32 on the surface of the protective film 30, thereby forming the protective film 30 resistant to external force. Furthermore, since all the manufacturing processes of the protective film 30 can be performed at room temperature, the function of the organic functional element 20 is not deactivated.

Moreover, in this invention, since the protective film 30 is formed without using the film-forming technique using a heat | fever or plasma, deterioration of the organic functional element 20 can be prevented.
In addition, since the siloxane compound layer 32 is formed only by irradiating the polysilane compound layer 31 with ultraviolet rays instead of laminating the siloxane compound layer on the polysilane compound layer by a film forming method using heat or plasma, the polysilane compound layer There is no possibility of damaging the film 31, and the protective film 30 can be easily formed.

  Examples and Comparative Examples are shown below to describe the effects of the present invention more specifically. However, the present invention is not limited to these Examples.

<Preparation of Example Sample>
First, polydimethylsilane (in the above formula (1), R ₁ = R ₂ = CH ₃ ) was selected as the polypolysilane compound. Next, a crucible filled with 100 mg of polydimethylsilane was placed in a vacuum chamber maintained at a vacuum degree of about 1.0 × 10 ⁻⁵ Pa, and this crucible was heated to form a film thickness of 1 on the organic EL element. A 0.0 μm polydimethylsilane film was formed. Here, the structure of the organic EL element is a glass substrate / ITO electrode / aluminum quinolyl complex / aromatic amine / aluminum electrode, and an area covering the entire organic film constituting the organic EL from the aluminum electrode side is polydimethylsilane. Was vapor-deposited (element 1). During the formation of the polydimethylsilane film, the organic EL element temperature was kept at room temperature.

Next, ultraviolet rays having a wavelength of 310 nm and a power of 80 μW / cm ² were generated by spectroscopy of a xenon light source at 23 ° C. in the air, and continuously irradiated on the polydimethylsilane side of the element 1 described above. In addition, in order to grasp | ascertain the relationship between irradiation time and the film thickness of each layer, the polydimethylsilane vapor deposition film | membrane of 1.0 micrometer was formed on the quartz glass substrate separately from the present Example. The absorbance of the deposited film when irradiated with the same ultraviolet ray as that irradiating the element 1 was measured in advance with a spectrophotometer and normalized with the absorbance at the start of the ultraviolet irradiation. The result is shown in FIG. As shown in FIG. 3, the time (8 minutes 30 seconds) during which the absorbance decreases to 50% at the start of irradiation is determined as the irradiation time for the element 1, and the siloxane compound film 0.5 μm, the polydimethylsilane film 0. A protective film of 5 μm was formed as an example. The formation of the siloxane compound was confirmed by measuring the oxygen atom composition ratio by X-ray photoelectron spectroscopy.

<Production of Comparative Sample>
Similar to the above-described example sample, first, polydimethylsilane (R ₁ = R ₂ = CH ₃ in the above formula (1)) was selected as the polysilane compound. Next, a crucible filled with 100 mg of polydimethylsilane was placed in a vacuum chamber maintained at a vacuum degree of about 1.0 × 10 ⁻⁵ Pa, and this crucible was heated to form a film thickness of 0 on the organic EL element. A .5 μm polydimethylsilane film was formed as a comparative example.

<Evaluation method>
The life test of the organic EL of the Example and Comparative Example in which the protective film was formed as described above was performed. In the life test, the examples and the organic EL were installed in an environment of normal temperature (23 ° C.) in air, and the luminance and drive voltage after the test period were confirmed.

<Evaluation results>
In the organic EL element of the comparative example covered only with the polydimethylsilane film having a thickness of 0.5 μm as the protective film, the luminance at the same driving voltage decreased to 35% of the initial value after the test period of 100 hours.
On the other hand, in the organic EL device of the example, no fluctuations in luminance and driving voltage were observed even after the test period of 300 hours. Therefore, the effectiveness of the protective film of the present invention was confirmed.

FIG. 1 is a schematic cross-sectional view showing a protective film according to an embodiment to which the present invention is applied. FIG. 2 is a graph showing the relationship between irradiation time and ultraviolet absorption intensity when polydibutylsilane is continuously irradiated with ultraviolet rays. FIG. 3 is a graph showing a change in absorbance of a polydimethylsilane deposited film according to an example of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Board | substrate, 20 ... Organic functional element, 30 ... Protective film, 31 ... Polysilane compound layer, 32 ... Siloxane compound layer

Claims (5)

A protective film for protecting an organic functional element formed on a substrate,
The protective film is a polysilane compound layer mainly composed of a polysilane compound provided on the organic functional element side so as to form an interface with the organic functional element ;
A protective film comprising a siloxane compound layer mainly composed of a siloxane compound provided continuously with the polysilane compound layer on a side opposite to the organic functional element. The protective film according to claim 1, further comprising a layer containing both the polysilane compound and the siloxane compound between the polysilane compound layer and the siloxane compound layer. A method for producing a protective film for protecting an organic functional element formed on a substrate,
Coating the organic functional element with a polysilane compound to form a polysilane compound layer;
The ultraviolet rays are irradiated to the surface of the polysilane compound layer, and a step of generating a siloxane compound to form a siloxane compound layer from the polysilane compound,
An ultraviolet irradiation condition corresponding to the film thickness of the siloxane compound layer is determined from a change in light absorption intensity of the polysilane compound layer with respect to ultraviolet irradiation, and the film thickness of the siloxane compound layer is controlled using the irradiation condition. A method for producing a protective film. A method for producing a protective film for protecting an organic functional element formed on a substrate,
Coating the organic functional element with a polysilane compound to form a polysilane compound layer;
The ultraviolet rays are irradiated to the surface of the polysilane compound layer, and a step of generating a siloxane compound to form a siloxane compound layer from the polysilane compound,
The irradiation condition of the ultraviolet ray corresponding to the film thickness of the siloxane compound layer is determined from the change in emission intensity of the polysilane compound layer with respect to the ultraviolet irradiation, and the film thickness of the siloxane compound layer is controlled using the irradiation condition. A method for manufacturing a protective film. 5. The method for producing a protective film according to claim 3 , wherein the wavelength of the ultraviolet ray is set to a light absorption maximum wavelength caused by a Si—Si bond of the polysilane compound. 6.

Images