WO2009099009A1

WO2009099009A1 - Organic el display and manufacturing method of the same

Info

Publication number: WO2009099009A1
Application number: PCT/JP2009/051585
Authority: WO
Inventors: Makoto Utsumi
Original assignee: Fuji Electric Holdings Co., Ltd.
Priority date: 2008-02-08
Filing date: 2009-01-30
Publication date: 2009-08-13
Also published as: TW200950574A

Abstract

Disclosed are an organic EL display and a manufacturing method for the same wherein the organic EL display can be operated stablyy over a long period of time through the use of a protective film that is highly resistant to moisture and that has a small extinction coefficient, which is the rate of light absorption. The organic EL display comprises a supporting substrate (10), an organic EL device (20) that includes arranged thereupon a lower electrode (11), an organic layer (12), and an upper electrode (13), and a protective layer (14) formed on the EL device. Protective layer (14) consists of one or more layers of inorganic films, of which at least one layer is a silicon nitride film that contains hydrogen, and in whichi the ratio of hydrogen within the silicon nitride film is 30at% or less.

Description

Organic EL display and manufacturing method thereof

The present invention relates to an organic EL display and a method for manufacturing the same, and more particularly to an organic EL display capable of preventing moisture from entering from the outside environment and realizing excellent luminous efficiency over a long period of time and a method for manufacturing the same.

In recent years, research on organic EL displays using self-luminous organic EL elements has been actively conducted. Organic EL displays are expected to achieve high luminous intensity and luminous efficiency because they can achieve high current density at low voltage. In particular, multi-color display capable of high-definition multi-color display and eventually full-color display is expected. The practical application of organic EL displays is expected.

An important practical issue for a color display is having a fine color display function and long-term stability including color reproducibility. However, the color organic EL display has a drawback that the light emission characteristic (current-luminance characteristic) is remarkably lowered by driving for a certain period.

A typical cause of the deterioration of the light emission characteristics is the growth of dark spots. This dark spot is a light emitting defect point. As the oxidation of the material proceeds during driving and storage, the growth of dark spots proceeds and spreads over the entire light emitting surface. The cause of dark spots is considered to be due to oxidation or aggregation of the laminated material constituting the element due to oxygen or moisture in the element. The growth proceeds not only during energization but also during storage, and in particular, (1) accelerated by oxygen or moisture present around the element, and (2) oxygen or moisture present as an adsorbate in the organic laminated film. (3) It is also considered that it is affected by moisture adsorbed on the component at the time of device fabrication or moisture penetration during production.

As a technique for preventing moisture from entering the organic laminated film in the element, conventionally, a method of capping the element forming portion using a metal can or a glass plate, or a method of using a desiccant in combination has been used. Recently, in order to make use of the characteristics of an organic EL display that is lightweight and thin, a technique of capping with a thin film without using a desiccant has attracted attention.

As the protective film used for this cap, silicon nitride, silicon nitride oxide, or the like is used. In order to suppress damage to the organic light emitting layer during film formation, the temperature rise of the film formation surface must be at least organic. It is necessary to suppress it below the glass transition temperature of the light emitting layer. For this reason, the film forming method developed in the semiconductor process cannot be applied, and there is a problem that a protective film having sufficient moisture resistance cannot be formed.

It is also known to use a plasma CVD method as a method for forming a protective film in an organic EL display (see, for example, Patent Documents 1 and 2). For example, Patent Document 1 proposes that a good protective film is obtained by forming a protective film mainly composed of a silicon nitride film on an electrode and defining the amount of Si—Si bonds in the nitride film. Yes.
JP 2005-285659 A (Claims etc.) JP 2007-184251 A (paragraph [0003] etc.)

In recent years, active drive organic EL displays have been actively put into practical use. In order to increase the aperture ratio, a top emission type structure that extracts light to the opposite side of the substrate on which the TFT circuit is built is mainly used. It is used. At this time, a transparent electrode and a sealing film are formed on the organic laminated film.

In general, the water vapor permeability rate of the sealing film is required to be less than 1 × 10 ⁻⁶ g / m ² / day. However, when the technique disclosed in Patent Document 1 is applied to this top emission type organic EL display, it absorbs visible light because it has a Si—Si bond in the protective film even though the moisture resistance is improved. Becomes higher. Therefore, when this protective film is formed on the transparent electrode, there is a problem that the light transmittance is lowered and the light emission efficiency of the organic EL element is lowered.

Various types of protective films have been studied in the past, but the conventional improvement techniques are techniques that mainly relieve stress to compensate for the poor adhesion of organic laminated films, and step coverage. The main technology is to improve the light resistance, and few have made it difficult to achieve both sufficient light transmission and waterproofness.

Accordingly, an object of the present invention is to provide an organic EL display that can be driven stably over a long period of time by using a protective film having a small extinction coefficient, which is a ratio of light absorption, and having high moisture resistance, and a method for manufacturing the same. It is to provide.

The present inventor examined the composition of a protective film formed by CVD (chemical vapor deposition), and found that there was a correlation between the content of hydrogen element in the film and moisture permeability. As a result, it has been found that the above problem can be solved by setting the protective film to have a specific hydrogen element ratio, and the present invention has been completed.

That is, the organic EL display of the present invention comprises a support substrate, an organic EL element formed on the support substrate and including a lower electrode, an organic layer and an upper electrode, and a protective layer formed on the organic EL element. In the organic EL display provided,
The protective layer is composed of one or more inorganic films, at least one of the inorganic films is a silicon nitride film containing hydrogen, and the element ratio of hydrogen in the silicon nitride film is 30 at% or less. It is characterized by being.

In the present invention, the silicon element ratio in the silicon nitride film is preferably 30 at% or more and 40 at% or less, and the nitrogen element ratio is preferably 35 at% or more and 40 at% or less. In addition, the organic EL display of the present invention includes a sealing substrate disposed opposite to the support substrate at a predetermined interval, and the support substrate and the sealing substrate are bonded to each other. Is preferred. In the present invention, the ratio of constituent elements can be calculated by Rutherford backscattering and elastic recoil detection methods.

Moreover, the manufacturing method of the organic EL display of this invention is a manufacturing method of the organic EL display of the said invention,
In forming the protective layer by chemical vapor deposition using monosilane, ammonia and nitrogen as source gases, the flow ratio of ammonia to monosilane is set to 0.5 to 1 and 27.12 MHz or 40.68 MHz. Film formation is performed using a high-frequency power source.

In the production method of the present invention, it is preferable that the protective layer is formed under conditions where the temperature of the support substrate is 70 ° C. or lower.

According to the present invention, because of the above configuration, it is possible to obtain a protective layer having a low extinction coefficient and high moisture resistance, thereby reducing the moisture intrusion route in the protective layer. It has become possible to realize a long-life organic EL display that can be driven stably over a long period of time and a manufacturing method thereof.

It is typical sectional drawing which shows an example of the organic electroluminescent display of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Support substrate 11 Lower electrode 12 Organic layer 13 Upper electrode 14 Protective layer 15 Adhesive layer 16 Laminate 20 such as a color filter Organic EL element 30 Sealing substrate 100 Organic EL display

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The example shown below is merely an example, and the design can be changed as appropriate within the scope of ordinary creation ability of those skilled in the art.

<Organic EL display>
FIG. 1 shows a schematic cross-sectional view of a preferred example of the organic EL display of the present invention. As shown in the drawing, an organic EL display 100 of the present invention is formed on a support substrate 10, an organic EL element 20 formed thereon, and including a lower electrode 11, an organic layer 12, and an upper electrode 13. A protective layer 14 is provided, and a sealing body 30 that is positioned above and is disposed to face the support body 10 at a predetermined interval. The support substrate 10 and the sealing substrate 30 are adhesive layers. 15 are bonded together. In the organic EL display 100 of the present invention, as described later, the organic EL element 20 is covered with the protective layer 14 including at least one silicon nitride film containing hydrogen at an element ratio of 30 at% or less. It has become possible to suppress moisture permeation into the organic laminated film without reducing the light transmittance as in the prior art.

(Support substrate)
As a material of the support substrate 10, any material that can withstand various conditions (for example, a solvent used, a temperature, and the like) used in forming the

layers

11, 12, and 13 sequentially stacked on the support substrate 10 is used. It is not particularly limited. Preferably, those having excellent dimensional stability are used. Examples of suitable materials include a glass substrate or a rigid resin substrate formed of an acrylic resin such as polyolefin or polymethyl methacrylate, a polyester resin such as polyethylene terephthalate, a polycarbonate resin, or a polyimide resin. Examples of other suitable materials include flexible films formed of acrylic resins such as polyolefin and polymethyl methacrylate, polyester resins such as polyethylene terephthalate, polycarbonate resins, and polyimide resins. Although not shown, a color filter layer, a thin film transistor (TFT), or a planarizing film may be formed on the support substrate 10.

(Organic EL device)
The organic EL element 20 according to the present invention includes the lower electrode 11, the organic layer 12, and the upper electrode 13 as described above.

(Lower electrode)
The lower electrode 11 has a function of charge injection into the organic layer 12 and connection with an external drive circuit. Desirable materials when the lower electrode 11 functions as a reflective electrode are made of a highly reflective metal (aluminum, silver, molybdenum, tungsten, nickel, chromium, or the like) or an amorphous alloy (NiP, NiB, CrP, or CrB). The thing which becomes. Particularly preferable reflective electrode materials include those made of a silver alloy from the viewpoint that a reflectance of 80% or more in visible light can be obtained. For example, an alloy of silver and at least one of group 8 nickel, rubidium, lead, and platinum, or an alloy of silver and at least one of group 2A magnesium and calcium Can be used.

Desirable materials when the lower electrode 11 functions as a transparent electrode include conductive metal oxides such as SnO ₂ , In ₂ O ₃ , In—Sn oxide, In—Zn oxide, ZnO, or Zn—Al oxide. Can be used.

(Organic layer)
The organic layer 12 is disposed between the lower electrode 11 and the upper electrode 13 and is a layer that forms the core of the light emitting unit. The organic layer 12 includes at least an organic light emitting layer, and includes a hole transport layer, a hole injection layer, an electron transport layer, and / or an electron injection layer as necessary. For example, the following layer configuration can be adopted for the organic layer 12.
(1) Organic light emitting layer (2) Hole injection layer / organic light emitting layer (3) Organic light emitting layer / electron injection layer (4) Hole injection layer / organic light emitting layer / electron injection layer (5) Hole transport layer / Organic light emitting layer / electron injection layer (6) Hole injection layer / hole transport layer / organic light emitting layer / electron injection layer (7) Hole injection layer / hole transport layer / organic light emitting layer / electron transport layer / electron injection Layer In each of the configurations (1) to (7), the electrode functioning as the anode is connected to the left side, and the electrode functioning as the cathode is connected to the right side.

A known material can be used for the organic light emitting layer. Examples of a material for obtaining blue to blue-green light emission include fluorescent brighteners such as benzothiazole, benzimidazole, or benzoxazole, metal chelated oxonium compounds (Alq ₃ (tris (8-quinolinol) aluminum) ), Styrylbenzene compounds (4,4′-bis (diphenylvinyl) biphenyl (DPVBi), etc.), aromatic dimethylidin compounds, condensed aromatic ring compounds, ring assembly compounds, or porphyrin compounds Compounds and the like are preferred.

Moreover, the organic light emitting layer which emits the light of a various wavelength range can also be formed by adding a dopant to a host compound. In this case, a distyrylarylene compound, N, N′-ditolyl-N, N′-diphenylbiphenylamine (TPD), Alq ₃ or the like can be used as the host compound. On the other hand, as dopants, perylene (blue purple), coumarin 6 (blue), quinacridone compounds (blue green to green), rubrene (yellow), 4-dicyanomethylene-2- (p-dimethylaminostyryl) -6- Methyl-4H-pyran (DCM, red), platinum octaethylporphyrin complex (PtOEP, red) or the like can be used.

For the hole transport layer, a material having a triarylamine partial structure, a carbazole partial structure, or an oxadiazole partial structure can be used. For example, it is preferable to use TPD, α-NPD, MTDAPB (o-, m-, p-), m-MTDATA, or the like.

For the hole injection layer, materials such as phthalocyanines (including copper phthalocyanine) or indanthrene compounds can be used.

The electron transport layer, aluminum complexes such as Alq _3, oxadiazole derivatives such as PBD or TPOB, triazole derivatives such as TAZ, triazine derivatives, such as thiophene derivatives such as phenyl quinoxaline compounds, or BMB-2T Materials can be used.

For the electron injection layer, a material such as an aluminum complex such as Alq ₃ or an aluminum quinolinol complex doped with an alkali metal or an alkaline earth metal can be used.

The organic layer 12 can be formed from each of the layers as described above. In addition to these layers, a buffer layer for further increasing the electron injection efficiency is optionally selected between the organic layer 12 and the upper electrode 13. It can also be formed (not shown). As the buffer layer, an electron injecting material such as an alkali metal, an alkaline earth metal or an alloy thereof, or a rare earth metal or a fluoride thereof can be used. Moreover, it is also preferable to form a damage mitigating layer (not shown) made of MgAg or the like on the organic layer 12 in order to mitigate damage when the upper electrode 13 is formed.

(Upper electrode)
The upper electrode 13 can be formed using the same material as that of the lower electrode 11 regardless of whether the upper electrode 13 functions as a reflective electrode or a transparent electrode.

Further, the transmittance of the upper electrode 13 is preferably 50% or more with respect to light having a wavelength of 400 to 800 nm in order to make the function of extracting light emitted from the organic layer 12 upward, and under the same conditions. More preferably, it is 85% or more.

(Protective layer)
The protective layer 14 is made of one or more inorganic films, and at least one of them is a silicon nitride film containing hydrogen. In the present invention, it is important that the element ratio of hydrogen in the silicon nitride film is 30 at% or less, for example, 25 to 29 at%. By setting the element ratio of hydrogen to 30 at% or less, a silicon nitride film having excellent moisture resistance can be obtained, and the desired effect of the present invention can be obtained. Preferably, the silicon nitride film has a silicon element ratio of 30 at% or more and 40 at% or less, and a nitrogen element ratio of 35 at% or more and 40 at% or less, whereby better moisture resistance can be obtained. it can. The ratio of each constituent element in the silicon nitride film can be calculated using Rutherford backscattering and elastic recoil particle detection methods. The elemental composition of this silicon nitride film is substantially 100 at% in terms of the total amount of hydrogen, silicon and nitrogen, but unintended impurities may be mixed into the film, so this trace amount of impurities is added as the balance. May be 100 at%.

The protective layer 14 satisfying the element ratio according to the present invention can be obtained by adjusting the film forming conditions in the CVD method or the like as will be described later. The protective layer 14 can be formed from a plurality of layers including a silicon nitride film that satisfies the above element ratio. For example, a silicon nitride film formed by changing the element ratio by changing the film forming conditions, or silicon oxynitride It can be a laminated film with a film.

(Adhesive layer)
The adhesive layer 15 is used to bond the support substrate 10 and the sealing substrate 30 (in the example shown in FIG. 1, the laminate 16 such as a color filter formed on the sealing substrate 30). Examples of the preferable adhesive layer 15 include those made of UV (ultraviolet) curable adhesive. As another preferable adhesive layer 15, an element for defining a distance between the support substrate 10 and the sealing substrate 30, for example, spacer particles such as glass beads, is contained in the UV curable adhesive. Is mentioned.

(Sealing substrate)
As a preferable sealing substrate 30, for example, a glass sealing substrate such as a glass substrate, a SUS can or an Al can, or an acrylic resin such as polyolefin or polymethyl methacrylate, a polyester resin such as polyethylene terephthalate, a polycarbonate resin or a polyimide resin is used. Examples thereof include a formed rigid resin substrate. Examples of other preferable sealing substrate 30 include a flexible film formed of an acrylic resin such as polyolefin or polymethyl methacrylate, a polyester resin such as polyethylene terephthalate, a polycarbonate resin, or a polyimide resin. Moreover, you may form the laminated body 16, such as a color filter, and a light conversion layer (not shown) using a transparent base material as the sealing substrate 30, as shown in the figure.

(Laminates such as color filters)
The laminate 16 such as a color filter includes a color filter and a color conversion layer. The color filter is a layer that transmits only light in a desired wavelength range. The color filter is effective in that the color purity of the light whose wavelength distribution is converted by the color conversion layer can be improved when the laminate 16 has a laminated structure with the color conversion layer. Examples of the color filter include those using a commercially available liquid crystal color filter material such as a color mosaic manufactured by FUJIFILM Electronics Materials Corporation.

(Light conversion layer)
The light conversion layer is a layer containing a fluorescent dye for color conversion, and may contain a matrix resin. This layer is a layer for performing wavelength distribution conversion on the light emitted from the organic EL element 20 and emitting light in different wavelength ranges. Here, the fluorescent dye constituting the light conversion layer is a dye that emits light in a desired wavelength range (for example, red, green, or blue).

Examples of the fluorescent dye that absorbs light in the blue to blue-green region and emits fluorescence in the red region include rhodamine B, rhodamine 6G, rhodamine 3B, rhodamine 101, rhodamine 110, sulforhodamine, basic violet 11, and basic red 2. Such as rhodamine dyes, cyanine dyes, pyridine dyes such as 1-ethyl-2- [4- (p-dimethylaminophenyl) -1,3-butadienyl] -pyridinium-perchlorate (pyridine 1), or oxazine System dyes and the like. Furthermore, various dyes (direct dyes, acid dyes, basic dyes, disperse dyes, etc.) can be used as long as they have fluorescence.

On the other hand, examples of fluorescent dyes that absorb light in the blue or blue-green region and emit fluorescence in the green region include, for example, 3- (2′-benzothiazolyl) -7-diethylaminocoumarin (coumarin 6), 3- (2 '-Benzimidazolyl) -7-diethylaminocoumarin (coumarin 7), 3- (2'-N-methylbenzimidazolyl) -7-diethylaminocoumarin (coumarin 30), 2,3,5,6-1H, 4H-tetrahydro-8 A coumarin dye such as trifluoromethylquinolidine (9,9a, 1-gh) coumarin (coumarin 153), or basic yellow 51 which is a coumarin dye dye, and further naphthalimide such as solvent yellow 11 and solvent yellow 116 System dyes and the like. Furthermore, various dyes (direct dyes, acid dyes, basic dyes, disperse dyes, etc.) can be used if they are fluorescent.

As the matrix resin constituting the light conversion layer, acrylic resin, various silicone polymers, or any material that can be substituted for them can be used. For example, straight silicone polymers and modified resin silicone polymers can be used.

The example of FIG. 1 shown above is an example of the organic EL display 100 including a single light emitting unit, but the organic EL display of the present invention is not limited to such a configuration, and a plurality of independently controlled multiple EL displays. A light emitting unit may be provided. For example, both the lower electrode and the upper electrode are electrode groups composed of a plurality of stripe electrodes, and the extending direction of the stripe electrodes constituting the lower electrode intersects with the extending direction of the stripe electrodes constituting the upper electrode. An example in which an organic layer is interposed between these electrodes is given. Such an example is a so-called passive matrix driving organic EL display. In such a case, it is preferable to make the above-described crossing directions orthogonal to each other because a display for displaying an arbitrary image and / or character can be configured.

As another example including a plurality of light emitting portions, a switching element composed of a plurality of thin film transistors formed on a substrate, a lower electrode composed of a plurality of portions connected in a one-to-one relationship, and an integrated transparent functioning as a common electrode The example which interposes an organic layer between electrodes is also mentioned. Such an example is a so-called active matrix driving organic EL display.

In both cases of passive matrix driving and active matrix driving, when a lower electrode composed of a plurality of electrodes is formed, an insulating oxide (SiOx, TiO ₂ , ZrO ₂ , AlOx, etc.) or an insulating property is used. An insulating film can be formed in the gap between the plurality of electrodes by using a nitride (AlNx, SiNx, etc.), a polymer material, or the like.

The example shown in FIG. 1 is a display for realizing monochrome display, but the present invention is not limited to such an example, and includes a multi-color display. When realizing a display of multi-color display, there are three types of units composed of the laminated body 16 such as the organic EL element 20, the light conversion layer, and the color filter shown in FIG. The color conversion layers included in the body 16 are red, green, and blue color conversion layers, and the color filters included in the stacked body 16 are associated with the color conversion layers of each unit, so that the three types of units Are combined into a pixel.

<Method for manufacturing organic EL display>
When the organic EL display shown in FIG. 1 is manufactured, the following forming steps can be employed.

(Organic EL element formation process)
[Lower electrode formation process]
In this step, the lower electrode 11 is formed on the support substrate 10. In the case of using a metal having a high reflectivity, vapor deposition or sputtering using resistance heating or electron beam heating can be used. In the case of vapor deposition, the film formation rate can be 0.1 to 10 nm / second at a film formation pressure of 1.0 × 10 ⁻⁴ Pa or less. On the other hand, when a sputtering method such as a DC magnetron sputtering method is used, an inert gas such as Ar can be used as the sputtering gas, and the film forming pressure can be set to about 0.1 to 2.0 Pa. In any of vapor deposition and sputtering, it is preferable that the forming atmosphere is a vacuum because excellent adhesion with an adjacent layer can be realized.

[Organic layer formation process]
In this step, the organic layer 12 is formed on the lower electrode 11. As the organic layer 12, an organic light emitting layer and an optional hole transport layer, hole injection layer, electron transport layer, and electron injection layer are deposited in a predetermined order using resistance heating or electron beam heating. Can be formed. It is important to form each layer constituting the organic layer 15 with a film thickness sufficient to achieve desired characteristics. The thickness of each layer constituting the organic layer 12 is 2 to 50 nm for the organic light emitting layer, 2 to 50 nm for the hole transport layer, 2 to 200 nm for the hole injection layer, 2 to 50 nm for the electron transport layer, The electron injection layer is preferably 2 to 50 nm.

Further, the buffer layer optionally formed between the organic layer 12 and the upper electrode 13 can be formed by vapor deposition using resistance heating or electron beam heating, and the film thickness depends on the driving voltage and transparency. Is preferably 10 nm or less.

[Upper electrode formation process]
In this step, the upper electrode 13 is formed on the organic layer 12. The upper electrode 13 can be formed using a sputtering method or a vapor deposition method. For example, an inert gas such as Ar can be used as the sputtering gas, and a DC magnetron sputtering method or the like can be used at a film forming pressure of about 0.1 to 2.0 Pa. At this time, in order to prevent the organic layer 12 from deteriorating, it is preferable not to directly irradiate the organic layer 12 with plasma formed on the target.

[Protective layer forming step]
In this step, the protective layer 14 is formed on the upper electrode 13. As described above, the protective layer 14 is made of one or more inorganic films including a silicon nitride film containing at least one layer of hydrogen, and can be formed using a CVD method, particularly a plasma CVD method.

Preferred conditions for forming a silicon nitride film that satisfies the conditions of the present invention are as follows. Monosilane, ammonia and nitrogen are used as the source gas, and the flow rate ratio of ammonia to monosilane is set to 0.5 or more and 1 or less. The pressure can be about 10 to 200 Pa, and a high frequency power source of 27.12 MHz or 40.68 MHz is used. The power density can be 0.1 W / cm ² to 2 W / cm ² . By performing film formation under such conditions, a silicon nitride film having excellent moisture resistance can be obtained. In order to prevent the substrate temperature from rising in the plasma during formation, it is desirable to control the temperature of the support substrate at this time to 70 ° C. or lower.

(Sealing structure forming process)
[Sealed body forming step]
A laminated body 16 (color filter and color conversion layer) such as a color filter is formed on the sealing substrate 30 as necessary. The laminate 16 such as a color filter is formed by applying a material of each layer by a known lamination method, that is, a spin coating method, a roll coating method, a casting method, a dip coating method, and the like, and then patterning by a photolithographic method or the like. Can be formed. Among these known formation methods, the formation method of the color filter layer is particularly established as the formation method of the color filter layer. Therefore, the formation method by the photolithographic method is preferable after the application by the spin coating method. When forming a plurality of types of color modulators such as color filters on one transparent substrate 30, a full color display can be realized by forming a plurality of types of color modulators in a matrix.

[Light conversion layer forming step]
In this process, a light conversion layer is formed on the sealing substrate 30 as necessary. When a light conversion layer is formed using a plurality of types of color conversion dyes, a plurality of types of color conversion dyes are premixed at a predetermined ratio to obtain a premixture obtained by mixing the matrix with a matrix resin. It can also be used for vapor deposition. Alternatively, multiple types of color conversion dye-containing matrix resins can be arranged in separate heating sites, and the resins containing the respective color conversion dyes can be separately heated to perform co-evaporation. In particular, co-evaporation is advantageous when there are large differences in characteristics such as vapor deposition rate and / or vapor pressure among a plurality of types of color conversion dyes.

In the case where a passivation film that covers the entire surface is optionally formed on the light conversion layer, a method such as plasma CVD can be used. In particular, from the viewpoint of preventing the deterioration of the light conversion layer, it is preferable to form the film at a substrate temperature of 100 ° C. or less.

[Bonding process of supporting substrate and sealing substrate]
As shown in FIG. 1, the support substrate 10 and the sealing substrate 30 are bonded together using an adhesive layer 15. As a bonding condition, any known bonding method can be used. In order to reduce the influence of heat on the organic layer 12, it is preferable to select an epoxy resin system that uses both ultraviolet curing and thermal curing. Thus, the organic EL display 100 of the present invention shown in FIG. 1 is obtained.

Hereinafter, the present invention will be described in detail with reference to examples, and the effects of the present invention will be demonstrated.
Example 1
In this example, a top emission type organic EL display (pixel number 2 × 2 (only red), pixel width 0.3 mm) was produced.

Fusion glass (Corning 1737 glass, 50 × 50 × 1.1 mm) was used as the support substrate 10. An Ag film having a thickness of 100 nm was deposited on the support substrate 10 by a sputtering method, and patterning was performed by a photolithographic method to form a stripe-shaped lower electrode 11 having a width of 0.3 mm.

Next, the support substrate 10 on which the lower electrode 11 was formed was placed in a resistance heating vapor deposition apparatus, and Li having a film thickness of 1.5 nm was deposited on the lower electrode 11 using a mask to form a cathode buffer layer. Subsequently, an organic layer 12 was obtained by sequentially depositing four layers of an electron transport layer / an organic EL layer / a hole transport layer / a hole injection layer using a resistance heating vapor deposition apparatus. The internal pressure of the vacuum chamber during film formation was 1 × 10 ⁻⁴ Pa. Each layer constituting the organic layer 15 was deposited at a deposition rate of 0.1 nm / s. As the electron transport layer, Alq ₃ (tris (8-quinolinol) aluminum) having a thickness of 20 nm was formed, and as the organic EL layer, DPVBi having a thickness of 30 nm was formed. Further, α-NPD having a film thickness of 10 nm was formed as the hole transport layer, and copper phthalocyanine having a film thickness of 100 nm was formed as the hole injection layer.

Subsequently, MgAg with a film thickness of 5 nm was deposited to form a damage mitigation layer when forming the transparent electrode. The laminate on which the organic layer 12 was formed was moved to the counter sputtering apparatus without breaking the vacuum. A metal mask was placed to deposit IZO having a film thickness of 100 nm, and a stripe-shaped transparent upper electrode 13 having a width of 0.3 mm extending in a direction perpendicular to the stripe of the lower electrode 11 was formed.

Next, the support substrate 10 on which the upper electrode 13 was formed was transported to a plasma CVD chamber, and a silicon nitride film was formed on the upper electrode 13 using monosilane gas and ammonia gas to obtain a protective layer 14. The flow rate of nitrogen was 2 L / min, the flow rate ratio of monosilane gas and ammonia gas was 1: 0.7, the film forming pressure was 100 Pa, the power of the high frequency power source of 27.12 MHz was 1 kW, and the temperature of the support substrate was 40 ° C. It was. As described above, an organic EL element 20 including the lower electrode 11 / the organic layer 12 / the upper electrode 13 and having the protective layer 14 formed thereon was obtained.

The composition of the obtained protective layer 14 was analyzed by Rutherford backscattering and elastic recoil particle detection methods. At this time, the composition ratios of Si, N, and H were 34 at%, 38 at%, and 28 at%, respectively.

On the other hand, a red filter material (CR7001, manufactured by FUJIFILM Electronics Materials) is applied to the transparent substrate (sealing substrate) 30, and 0.5 mm × 0.5 mm at a position corresponding to the light emitting portion of the organic EL element 20. A red color filter layer having a thickness of 1.5 μm was formed.

Next, the laminate on which the color filter layer was formed was conveyed to a resistance heating vapor deposition apparatus, and a light conversion layer containing coumarin 6 and DCM-2 was produced. A 300 nm-thick photoconversion layer was formed by co-evaporation in which coumarin 6 and DCM-2 were heated in separate crucibles in the vapor deposition apparatus. At this time, the heating temperature of each crucible was controlled so that the deposition rate of coumarin 6 was 0.3 nm / s and the deposition rate of DCM-2 was 0.005 nm / s. In the light conversion layer of this example, the molar ratio of coumarin 6 and DCM-2 is 49: 1 based on the total number of constituent molecules.

Next, the support substrate 10 on which the organic EL element 20 is formed and the transparent substrate 30 on which the color filter layer is formed are carried into a bonding apparatus having an oxygen concentration of 5 ppm or less and a water concentration of 5 ppm or less to form a red color filter layer. The adhesive layer 15 was dropped on the outside of the sealing substrate 30 using an epoxy-based ultraviolet curable adhesive. The support substrate 10 including the organic EL element 20 is disposed so as to face the red color filter layer, and after the pressure inside the apparatus is reduced to about 10 Pa, the light emitting portion of the organic EL element 20 and the red color filter layer are aligned. Both laminates were bonded together, and the inside of the apparatus was returned to atmospheric pressure.

Next, using a mask, only the adhesive layer 15 was irradiated with ultraviolet rays to be temporarily cured, put in a heating furnace and heated to 80 ° C. for 1 hour, and then naturally cooled in the furnace for 30 minutes. Thereafter, the bonded body was taken out from the apparatus to obtain an organic EL display.

(Comparative Example 1)
The protective layer was formed under the conditions except that the flow ratio of monosilane gas and ammonia gas was 1: 1.1, the film forming pressure was 100 Pa, the power of the high frequency power supply at 27.12 MHz was 1 kW, and the temperature of the support substrate was 40 ° C. In the same manner as in Example 1, an organic EL display was produced.

The composition of the protective layer was analyzed by Rutherford backscattering and elastic recoil detection methods. At this time, the composition ratios of Si, N, and H were 29 at%, 38 at%, and 33 at%, respectively.

(Comparative Example 2)
The protective layer was formed except that the flow rate ratio of monosilane gas and ammonia gas was 1: 0.4, the film forming pressure was 100 Pa, the power of the high frequency power supply at 27.12 MHz was 1 kW, and the temperature of the support substrate was 40 ° C. In the same manner as in Example 1, an organic EL display was produced.

The composition of the protective layer was analyzed by Rutherford backscattering and elastic recoil detection methods. At this time, the composition ratios of Si, N, and H were 42 at%, 31 at%, and 27 at%, respectively.

The organic EL displays of Examples and Comparative Examples formed as described above were continuously driven at a current density of 0.1 A / cm ^{2 in} an environment of 60 ° C. and 90 RH%, and voltage and luminance were measured. The value obtained by dividing the luminance by the current value is calculated as the luminous efficiency, and the retention ratio of the luminous efficiency at 1000 hours when the initial luminous efficiency is 1 is shown in Table 1 below.

From the results in Table 1 above, it can be seen that in each example satisfying the conditions of the present invention, excellent results were obtained in the maintenance efficiency of luminous efficiency. As described above, in the examples within the scope of the present invention, a result excellent in the life characteristics was obtained, but in each comparative example that departs from the scope of the present invention, it is understood that the life is short. This is presumably because moisture intruded from the protective layer in the comparative example.

Next, the film forming conditions of the silicon nitride film were changed as shown in Table 2 below, and the moisture resistance of the resulting silicon nitride film was evaluated. The film forming conditions other than those shown in the following Table 2 were a support substrate temperature of 50 ° C., a power density of 0.5 W / cm ² , a film forming pressure of 100 Pa, and a nitrogen flow rate of 2 L / min. The evaluation of moisture resistance is made by comparing the area ratio of the unaltered portion of the Ca film after each protective layer is formed to a thickness of 3 μm on a 100 nm-thick Ca film and left in a constant temperature bath at 95 ° C. and 50 RH% for 1000 hours. did. The results are also shown in Table 2 below.

In addition, the element ratio in the obtained silicon nitride film is H, Si, N, and the remainder (which is due to impurities in the source gas, film forming chamber material, and mixing of cleaning gas, and is less than 0.5 at%) The total amount was 100 at%. The unit of flow rate “sccm” in the table below is a flow rate unit “standard cc / min” normalized at 0 ° C. and 1 atm.

As shown in Table 2 above, when the ammonia gas (NH ₃ ) flow rate is lower than 50 sccm, the nitrogen content in the film is small. Moreover, when it becomes lower than 40 sccm, absorption of visible light comes to be seen notably. In the silicon nitride film in this region, a uniform film is not formed, and it is assumed that SiN bonds, SiH bonds, and SiSi bonds are mixed. In addition, the number of pinholes in the Ca film was large, and the area of the altered portion was large. From this, it is judged that the moisture resistance of the film is low.

When the NH ₃ flow rate was 50 sccm to 100 sccm, the nitrogen content in the film approached the stoichiometric ratio of the silicon nitride film, and the hydrogen content in the film was less than 30 at%. In addition, the number of pinholes in the Ca film was small, and the area of the altered portion was small.

On the other hand, when the NH ₃ flow rate exceeded 100 sccm, the nitrogen content in the film increased, but the hydrogen content also increased. In addition, the number of pinholes in the Ca film increased and the area of the altered portion increased. This is assumed to be due to an increase in NH bonds in the film.

It should be noted that the stress of these films was within ± 50 MPa, and it was confirmed that no film peeling occurred even when formed on the upper electrode.

From these results, when the hydrogen content in the film is less than 30 at%, particularly when the silicon content is 30 to 40 at% and the nitrogen content is 35 to 40 at%, a highly moisture-proof film can be obtained. It was confirmed that This corresponds to a case where the flow rate ratio between monosilane, which is a raw material gas, and ammonia gas is 0.5 or more and 1 or less.

Further, a good silicon nitride film was obtained even when the power supply frequency was changed to 40.68 MHz. However, when the frequency was set to 13.56 MHz, the nitrogen content in the film was reduced, and the hydrogen ratio was increased to 30 at%. Phenomenon exceeding was seen. This is presumably because the ammonia gas is not sufficiently decomposed in the reaction chamber, so that it is difficult to be taken into the film.

According to the present invention, it is possible to improve the life characteristics of an organic EL display that has been a problem in the past. For this reason, the organic EL display of the present invention can achieve excellent luminous efficiency over a long period of time. Therefore, it can be said that the present invention is a promising technology in a situation where development of an organic EL display having higher light emission efficiency has been demanded in recent years.

Claims

In an organic EL display comprising a support substrate, an organic EL element formed on the support substrate and including a lower electrode, an organic layer and an upper electrode, and a protective layer formed on the organic EL element.
An organic EL display, wherein the protective layer includes a silicon nitride film containing hydrogen, and an element ratio of hydrogen in the silicon nitride film is 30 at% or less.
2. The organic EL display according to claim 1, wherein the silicon element ratio in the silicon nitride film is 30 at% or more and 40 at% or less, and the nitrogen element ratio is 35 at% or more and 40 at% or less.
2. An organic EL display according to claim 1, further comprising a sealing substrate disposed opposite to the support substrate at a predetermined interval, wherein the support substrate and the sealing substrate are bonded together.
3. An organic EL display according to claim 2, comprising a sealing substrate disposed opposite to the support substrate at a predetermined interval, and the support substrate and the sealing substrate are bonded together.
2. The organic EL display according to claim 1, wherein the ratio of the constituent elements is calculated by Rutherford backscattering and elastic recoil detection method.
3. The organic EL display according to claim 2, wherein the ratio of constituent elements is calculated by Rutherford backscattering and elastic recoil detection method.
An organic EL display manufacturing method comprising: a support substrate; an organic EL element formed on the support substrate and including a lower electrode, an organic layer, and an upper electrode; and a protective layer formed on the organic EL element. ,
In forming the protective layer by chemical vapor deposition using monosilane, ammonia and nitrogen as source gases, the flow ratio of ammonia to monosilane is set to 0.5 to 1 and 27.12 MHz or 40.68 MHz. The organic layer is formed by using a high-frequency power source, wherein the protective layer includes a silicon nitride film containing hydrogen, and the elemental ratio of hydrogen in the silicon nitride film is 30 at% or less Manufacturing method of EL display.
The method for manufacturing an organic EL display according to claim 7, wherein the silicon element ratio in the silicon nitride film is 30 at% or more and 40 at% or less, and the nitrogen element ratio is 35 at% or more and 40 at% or less.
A method for manufacturing an organic EL display according to claim 7, comprising a sealing substrate disposed opposite to the support substrate at a predetermined interval, and the support substrate and the sealing substrate are bonded together.
9. A method of manufacturing an organic EL display according to claim 8, further comprising a sealing substrate disposed opposite to the support substrate at a predetermined interval, wherein the support substrate and the sealing substrate are bonded together.
The method for producing an organic EL display according to claim 7, wherein the ratio of the constituent elements is calculated by Rutherford backscattering and elastic recoil detection method.
The method for producing an organic EL display according to claim 8, wherein the ratio of the constituent elements is calculated by Rutherford backscattering and elastic recoil detection method.
The method for producing an organic EL display according to claim 7, wherein the protective layer is formed under a condition that the temperature of the support substrate is 70 ° C or lower.
The method for producing an organic EL display according to claim 8, wherein the protective layer is formed under a condition that the temperature of the support substrate is 70 ° C or lower.