JP2013206811A - Organic electroluminescent panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable organic electroluminescent panel, by minimizing optical loss due to a passivation layer being laminated, without reducing the emission efficiency.SOLUTION: A top emission or double side emission organic electroluminescent panel includes at least a first electrode layer, an organic emission medium layer including an organic emission layer, a second electrode layer, a passivation layer, and an adhesive layer, in this order, on a substrate. The passivation layer contains at least silicon nitride, and has a film density which is 2.4 g/cmor more at a part in contact with the second electrode layer, and decreases gradually toward the adhesive layer where the film density is 1.6 g/cmor less.

Description

  The present invention relates to an organic electronic device using an organic material, and more particularly to an organic electroluminescence panel.

  In recent years, electronic devices using organic materials have been actively studied. Examples of organic electronic devices include organic thin film transistors that use semiconducting organic materials as semiconductor materials, and organic electroluminescent display devices that use organic light emitting materials that emit light when electricity is applied. By placing an organic material between them and applying a voltage between the electrodes, the functions of the organic material such as semiconductor properties and light emission are expressed.

  These organic materials can be made by a printing process or the like under atmospheric pressure without using a vacuum process necessary for forming a conventional inorganic semiconductor material, etc. It is advantageous that it is provided on a plastic substrate. However, organic materials have a drawback that they are vulnerable to deterioration with time, and have not yet been put into practical use.

  In particular, organic electroluminescence panels are expected to be used in a wide range of applications such as flat panel displays and lighting used in televisions, personal computer monitors, mobile devices, and the like. Organic electroluminescence is self-luminous, unlike liquid crystal displays, etc., so it can be structurally made extremely thin, the display image can be viewed with a wide viewing angle, the response speed of the display image is fast, and the power consumption is low. In view of the advantages such as high contrast, it is expected to be used as a flat panel display instead of a cathode ray tube or a liquid crystal display, but the deterioration of the organic light emitting material over time is a problem.

  FIG. 3 shows a cross-sectional structure of an organic electroluminescence panel according to the prior art. The conventional organic electroluminescence panel structure is sealed using a sealing substrate 27 made of a glass cap in a configuration in which a first electrode layer 24, an organic light emitting medium layer 23, and a second electrode layer 24 are provided on a substrate 21. It has stopped. The sealing substrate 27 is fixed to the substrate 21 through the adhesive layer 25, and a desiccant 26 is attached to the inside of the sealing substrate 27. However, the cost of the glass cap itself used for the sealing substrate 27 is high, and when the size is increased, the deflection of the glass cap becomes conspicuous. Therefore, an organic electroluminescence panel having a flat structure has been proposed. In the organic electroluminescence panel, the sealing substrate is directly attached onto the laminate on the substrate side by an adhesive layer. In the organic electroluminescence panel having a flat structure, since there is no space for attaching the desiccant inside the sealing substrate, a passivation layer is formed between the adhesive layer and the second electrode layer to suppress deterioration. By applying such a thin film structure, the organic electroluminescence panel can produce an extremely thin display. The passivation layer preferably has a high barrier property against oxygen and water and has an insulating property because it is formed on the cathode, and examples thereof include silicon oxide and silicon nitride.

  However, since the organic electroluminescence panel has only a thickness of about 1 μm from the first electrode layer to the second electrode layer, the presence of a foreign substance having the same thickness as this increases the dark spot and generates non-lighted pixels. Although a light emission defect is caused, it is difficult to completely remove foreign matters from the process.

  Therefore, the passivation film, which is the most effective means for suppressing light emission defects, improves the sealing characteristics by suppressing the adverse effects of moisture and oxygen from the outside, and suppresses light emission defects caused by foreign matters mixed in the process. In order to achieve this, a film is formed. The passivation film is formed using a vacuum deposition method, a sputtering method, a CVD method, or the like.

  As a film having a high effect as a passivation film, for example, by controlling the film density, a film in which the step shape of the organic electroluminescence panel and the step coverage with respect to foreign matter adhered in the process are improved, and a film in which the barrier property is improved. Have been proposed (for example, Patent Documents 1 and 2).

  However, when the passivation layer is formed under the above conditions, since the density is changed stepwise, the light generated by the organic electroluminescence is reflected at the interface between the film where the change occurs and the original layer is reflected. The light cannot be extracted sufficiently. In addition, since the density difference between the passivation layer and the adhesive layer interface is particularly large, light cannot be sufficiently extracted by reflection here. Thus, it is very difficult to achieve both sealing characteristics and light extraction from organic electroluminescence.

JP 2007-184251 A JP 2007-220646 A

  The present invention has been made in view of the above problems, and without reducing the original light emission efficiency of an organic electronic device, particularly an organic electroluminescence panel, suppresses optical loss due to the laminated passivation layer as much as possible, and is reliable. An object of the present invention is to provide an organic electroluminescence panel having a high height.

In response to the above problem, the organic electroluminescence panel according to the first invention includes at least a first electrode layer, an organic light emitting medium layer including an organic light emitting layer, a second electrode layer, a passivation layer, and an adhesive layer on a substrate. A top emission type or double-sided emission type organic electroluminescence panel provided in order, wherein the passivation layer contains at least silicon nitride and has a film density of 2.4 g / cm ³ in contact with the second electrode layer. As described above, the density gradually decreases toward the adhesive layer, and is 1.6 g / cm ³ or less at a portion in contact with the adhesive layer.

  Further, the organic electroluminescence panel according to the second invention is the organic electroluminescence panel according to the first invention, wherein the passivation layer has a density ranging from a position in contact with the second electrode layer to a position in contact with the adhesive layer. It is characterized by having no interface due to the difference.

  The organic electroluminescence panel according to the third invention is the organic electroluminescence panel according to the first or second invention, wherein the light transmittance in the visible light region of the passivation layer is 90% or more. And

Moreover, the organic electroluminescence panel according to the fourth invention is the organic electroluminescence panel according to any one of the first to third inventions, wherein the water vapor transmission rate of the passivation layer is 0.01 g / m ^2. -It is below day.

  Moreover, the organic electroluminescence panel according to the fifth invention is the organic electroluminescence panel according to any one of the first to fourth inventions, wherein the total thickness of the passivation layer is 2 μm or less. Features.

According to the present invention, the conditions for forming a passivation film after forming a second electrode layer of an organic electronic device, in particular, an organic electroluminescence panel, for example, changing SiH ₄ flow rate, NH ₃ flow rate, and plasma power continuously. The film can be formed without degrading the characteristics of the organic electroluminescence panel, and both the visible light transmittance and the water vapor transmittance are compatible. An organic electroluminescence panel capable of preventing the spread can be provided.

Sectional drawing which shows the structure of one Example of the organic electroluminescent panel of this invention (A) And (b) is the graph explaining the conditions which manufacture the organic electroluminescent panel of FIG. Sectional drawing which shows the structure of the conventional organic electroluminescent panel

  The organic electronic device of the present invention and the manufacturing method thereof will be described below based on an embodiment using FIG. 1 by taking an organic electroluminescence panel as an example, but the present invention is not limited to this. Moreover, although a double-sided light emitting structure is mentioned as an example as an organic electroluminescent panel, a top emission structure is applicable. FIG. 1 is a cross-sectional view showing an embodiment of the organic electroluminescence panel of the present invention. The organic electroluminescence panel of the present invention includes a plurality of organic EL elements each including at least a first electrode layer 12, an organic light emitting medium layer 13, and a second electrode layer 14. More specifically, a plurality of first electrode layers 12 patterned on the substrate 11, a plurality of organic light emitting medium layers 13 formed on the plurality of first electrode layers 12, and a plurality of organic light emitting medium layers 13. The second electrode layer 14 formed so as to cover the substrate, the passivation layer 15 formed so as to cover the second electrode layer 14, and the adhesive layer 17 formed for bonding the substrate 11 and the sealing substrate 18 together. And a sealing substrate 18. The passivation layer 15 functions as a protective layer for protecting the organic light emitting medium layer 13 from the outside air.

  As the substrate 11 according to the present invention, for example, an insulating substrate such as glass or plastic film can be used. In particular, in the case of a bottom emission type in which light emission is extracted from the substrate side, a light-transmitting material is used as the material of the substrate 11. As a material for the light-transmitting substrate, it is only necessary that at least a first electrode layer 12 described later is formed on a plastic film such as glass, quartz, polyethersulfone, or polycarbonate. In the case of forming an active matrix organic EL element, the substrate 11 is a driving substrate on which a thin film transistor (TFT) is formed, and a known thin film transistor can be used as the thin film transistor to be used. Specifically, a thin film transistor mainly including an active layer in which a source / drain region and a channel region are formed, a gate insulating film, and a gate electrode can be given. The structure of the thin film transistor is not particularly limited, and examples thereof include a staggered type, an inverted staggered type, a bottom gate type, a top gate type, and a coplanar type. As a material of the semiconductor layer of the thin film transistor, materials such as polythiophene, polyaniline, copper phthalocyanine, and perylene derivatives may be used, and amorphous silicon, polysilicon, and metal oxide may be used. Further, a color filter layer, a light scattering layer, a light polarizing layer, or the like may be provided on the substrate on either side of the substrate 11.

  These substrates 11 are desirably heat-treated in advance to reduce the moisture in the substrate or on the surface as much as possible. Further, in order to improve the adhesion depending on the material laminated on the substrate 11, it is preferable to use after performing surface treatment such as ultrasonic cleaning treatment, corona discharge treatment, plasma treatment, UV ozone treatment. .

  Next, the first electrode layer 12 is formed on the substrate 11.

  In order to connect the thin film transistor so as to function as a switching element of the organic EL display, the drain electrode of the thin film transistor and the first electrode layer 12 of the organic EL element constituting each pixel of the organic EL display are electrically connected. . The connection between the thin film transistor, the drain electrode, and the first electrode layer 12 of the organic EL display is made through a connection wiring formed in a contact hole that penetrates the planarization film.

  Further, the first electrode layer 12 is partitioned by a partition wall 16 and becomes a pixel electrode corresponding to each pixel. As the material of the first electrode layer 12, it is preferable to select a material having a high work function such as ITO. Metal composite oxides such as ITO (indium tin composite oxide), indium zinc composite oxide, and zinc aluminum composite oxide Alternatively, a single layer or a laminate of metal materials such as gold and platinum, or fine particle dispersion films in which fine particles of these metal oxides or metal materials are dispersed in an epoxy resin or an acrylic resin can be used. In addition, as in the case of a top emission type organic EL display, when a hole injection property and a reflection property are required as the first electrode layer 12, an ITO film is laminated on a metal material such as Ag or Al. do it. Although the optimal value of the film thickness of the first electrode layer 12 varies depending on the element configuration of the organic EL display, it is not less than 10 nm and not more than 1000 nm, more preferably not more than 300 nm, regardless of single layer or stacked layers.

  As a formation method of the first electrode layer 12, depending on the material, dry film formation methods such as resistance heating evaporation method, electron beam evaporation method, reactive evaporation method, ion plating method, sputtering method, gravure printing method, A wet film formation method such as a screen printing method can be used.

After the first electrode layer 12 is formed, partition walls 16 are formed between adjacent anode patterns by photolithography. More specifically, it includes at least a step of applying a photosensitive resin composition to a substrate and a step of forming a partition wall pattern by pattern exposure, development, and baking. The partition wall 16 is formed so as to partition the light emitting region corresponding to the pixel. In general, in an active matrix drive type display device, a first electrode layer 12 is formed for each pixel, and each pixel tries to occupy as wide an area as possible, so that the end of the first electrode layer 12 is covered. The most preferable shape of the partition wall formed in the above is based on a lattice shape. In addition, the partition walls can be multi-staged. In that case, an insulating inorganic film made of SiO ₂ or SiN formed on the entire surface of the substrate 11 is formed in a lattice shape that separates pixels by a photolithography process. A first-stage partition is formed, and a second-stage partition made of a photosensitive resin is formed on the first-stage partition by photolithography.

  The photosensitive material for forming the partition wall 16 may be either a positive resist or a negative resist, and may be a commercially available one, but must have insulating properties. If the partition wall does not have sufficient insulation, a current flows to the adjacent pixel electrode through the partition wall, resulting in a display defect. Also, proper display may not be possible due to TFT malfunction. Specific examples of the photosensitive material include, but are not limited to, polyimide, acrylic resin, novolac resin, and fluorene. Further, for the purpose of improving the display quality of the organic EL display, a light shielding material may be included in the photosensitive material. Further, if necessary, a water repellent can be added, or plasma or UV can be irradiated to impart liquid repellency to the ink after formation.

  The photosensitive resin forming the partition 16 is applied using a known coating method such as a spin coater, bar coater, roll coater, die coater, or gravure coater. Next, in the step of pattern exposure and development to form the partition wall pattern, the partition wall pattern can be formed by a conventionally known exposure and development method. Regarding firing, firing can be performed by a conventionally known method using an oven, a hot plate or the like.

  The partition wall 16 desirably has a thickness in the range of 0.5 μm to 5.0 μm. This can prevent color mixing with adjacent pixels when performing separate coating for each pixel using an organic light emitting ink in which organic light emitting materials having different luminescent colors are dissolved or dispersed in a solvent. Note that if the partition wall is too low, the effect of preventing leakage current between adjacent pixels, prevention of short-circuiting, and prevention of color mixing of the organic light emitting ink may not be obtained.

  Subsequently, the organic light emitting medium layer 13 includes an organic light emitting layer that emits light upon application of a voltage. Although it may be constituted by a single layer composed of the organic light emitting layer, it may be constituted by a laminated structure in which a light emitting auxiliary layer for improving luminous efficiency is laminated in addition to the light emitting layer. Examples of the light emission auxiliary layer include a hole transport layer, a hole injection layer, an electron transport layer, and an electron injection layer.

Examples of hole transport materials include metal phthalocyanines such as copper phthalocyanine and tetra (t-butyl) copper phthalocyanine and metal-free phthalocyanines, quinacridone compounds, 1,1-bis (4-di-p-tolylaminophenyl) Cyclohexane, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine, N, N′-di (1-naphthyl) -N, Aromatic amine low molecular hole injection and transport materials such as N′-diphenyl-1,1′-biphenyl-4,4′-diamine, polyaniline, polythiophene, polyvinylcarbazole, poly (3,4-ethylenedioxythiophene) ) and polymer hole transport materials such as a mixture of polystyrene sulfonic acid, polythiophene oligomer _{materials, Cu 2 O, Cr 2 O} 3, Mn 2 O 3, F Ox (x~0.1), NiO, CoO , Pr 2 O 3, Ag 2 O, MoO 2, Bi 2 O 3, ZnO, TiO 2, SnO 2, ThO 2, V 2 O 5, Nb 2 O 5 , Ta ₂ O ₅ , MoO ₃ , WO ₃ , MnO ₂ and other inorganic materials, and other existing hole transport materials.

  In the case of a polymer EL display, an interlayer layer is preferably formed on the hole transport material. Examples of materials used for the interlayer layer include polymers containing aromatic amines such as polyvinyl carbazole or derivatives thereof, polyarylene derivatives having aromatic amines in the side chain or main chain, arylamine derivatives, and triphenyldiamine derivatives. . These materials can be dissolved or dispersed in a solvent and formed using various coating methods such as spin coating or letterpress printing.

  As the light-emitting material, 9,10-diarylanthracene derivatives, pyrene, coronene, perylene, rubrene, 1,1,4,4-tetraphenylbutadiene, tris (8-quinolinolato) aluminum complex, tris (4-methyl-8-) Quinolinolato) aluminum complex, bis (8-quinolinolato) zinc complex, tris (4-methyl-5-trifluoromethyl-8-quinolinolato) aluminum complex, tris (4-methyl-5-cyano-8-quinolinolato) aluminum complex, Bis (2-methyl-5-trifluoromethyl-8-quinolinolato) [4- (4-cyanophenyl) phenolate] aluminum complex, bis (2-methyl-5-cyano-8-quinolinolato) [4- (4- Cyanophenyl) phenolate] aluminum complex, tri (8-quinolinolato) scandium complex, bis [8- (para-tosyl) aminoquinoline] zinc complex and cadmium complex, 1,2,3,4-tetraphenylcyclopentadiene, pentaphenylcyclopentadiene, poly-2,5- Diheptyloxy-para-phenylene vinylene, coumarin phosphor, perylene phosphor, pyran phosphor, anthrone phosphor, porphyrin phosphor, quinacridone phosphor, N, N'-dialkyl-substituted quinacridone phosphor , Naphthalimide-based phosphors, N, N′-diaryl-substituted pyrrolopyrrole-based phosphors, phosphorescent phosphors such as Ir complexes, and other low-molecular light-emitting materials, polyfluorene, polyparaphenylenevinylene, polythiophene, polyspiro, etc. Of these low molecular weight materials. Or copolymerized material and can be used other conventional fluorescent light emitting material or phosphorescent material.

  Examples of electron transport materials include 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole, 2,5-bis (1-naphthyl) -1 , 3,4-oxadiazole, oxadiazole derivatives, bis (10-hydroxybenzo [h] quinolinolato) beryllium complexes, triazole compounds, and the like can be used. Alternatively, these electron transport materials may be used as an electron injection layer by doping a small amount of alkali metal or alkaline earth metal having a low work function such as sodium, barium, or lithium.

  The film thickness of the organic light-emitting medium layer 13 is 1000 nm or less, preferably about 50 nm to 200 nm, even when formed by a single layer or a stacked layer. As a method for forming the organic light emitting medium layer 13, depending on the material, a vacuum deposition method or a coating method such as slit coating, spin coating, spray coating, nozzle coating, flexographic printing, gravure printing, intaglio offset printing, letterpress offset printing, etc. Or a printing method, an inkjet method, or the like can be used.

  Subsequently, the second electrode layer 14 is formed. As the second electrode layer 14, a substance having a high electron injection efficiency into the organic light emitting medium layer 13 and a low work function is used. Specifically, a single metal such as Mg, Al, Yb is used, or a compound such as Ba, Ca, Li, its oxide, fluoride, etc. is sandwiched about 1 nm at the interface in contact with the light emitting medium. High Al and Cu can be laminated and used. Alternatively, in order to achieve both electron injection efficiency and stability, one or more metals such as Li, Mg, Ca, Sr, La, Ce, Er, Eu, Sc, Y, and Yb having a low work function and stable Ag, Al Alternatively, an alloy system with a metal element such as Cu may be used. Specifically, alloys such as MgAg, AlLi, and CuLi can be used. In the case of a so-called top emission structure or double-sided light emitting structure in which light is extracted from the second electrode side, a light-transmitting material must be selected. In this case, after thinly providing Li and Ca having a low work function, a metal composite oxide such as ITO (indium tin composite oxide), indium zinc composite oxide, or zinc aluminum composite oxide may be laminated. The organic light emitting medium layer 13 may be laminated with a metal oxide such as ITO by doping a small amount of a metal such as Li or Ca having a low work function. As a method for forming the second electrode layer 14, a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, or a sputtering method can be used depending on the material. Although there is no restriction | limiting in particular in the thickness of the 2nd electrode layer 14, When visible light transmittance is considered, about 10 nm-200 nm are desirable.

  Subsequently, a passivation layer 15 is formed on the second electrode layer 14 as a barrier layer for protecting the organic EL element from air and moisture. Examples of the material for the passivation layer 15 include metal oxides such as silicon oxide and aluminum oxide, metal fluorides such as aluminum fluoride and magnesium fluoride, metal nitrides such as silicon nitride, aluminum nitride, and carbon nitride, silicon oxynitride, and the like. Metal oxynitrides, metal carbides such as silicon carbide, or laminates thereof can be used, and if necessary, polymer resin films such as acrylic resins, epoxy resins, silicone resins, polyester resins and the like It may be used as a laminated film. In particular, it is preferable to use silicon oxide, silicon oxynitride, or silicon nitride from the viewpoint of barrier properties and transparency. Furthermore, by using a laminated film or a gradient film with a variable film density, it is possible to provide step coverage and barrier. It can be set as the film | membrane which balances property.

The passivation layer 15 is preferably formed so as to cover the entire surface of the second electrode layer 14, and the second electrode layer 14 is preferably formed to be covered with the substrate 11 and the passivation layer 15. As a method for forming the passivation layer 15, a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, a sputtering method, and a CVD method can be used depending on the material. It is preferable to use the CVD method because the film density and film composition can be easily varied depending on the surface of the step coverage and the film forming conditions. As the CVD method, a thermal CVD method, a plasma CVD method, a catalytic CVD method, a VUV-CVD method, or the like can be used. In addition, as a reaction gas in the CVD method, a gas such as N ₂ , O ₂ , NH ₃ , H ₂ , or N ₂ O is added to an organic silicon compound such as monosilane, hexamethyldisilazane (HMDS), or tetraethoxysilane. The film density may be changed by changing the gas flow rate of silane or the like, or the plasma power, if necessary. Hydrogen or carbon may be added to the film by the reactive gas used. It can also be contained. In the present invention, a silicon nitride film is employed by a plasma CVD method that can easily control film quality such as stress, visible light transmittance, and water vapor transmittance.

  When the absolute value of the residual film stress of the passivation layer 15 is large, the organic EL element is peeled off and the barrier property is impaired. The film stress is a force that warps the substrate by a film formed on the substrate, and is called tensile stress (positive value) or compressive stress (negative value) depending on the direction of warping. If the tensile stress is excessive, cracks are likely to occur, and if the compressive stress is excessive, problems such as peeling of the underlayer are suppressed. Therefore, the film stress of at least the first film is preferably ± 100 MPa or less. Further, the passivation layer 15 may be a laminated film of layers having different densities, and even in the case of a laminated film, the absolute value of the total accumulated film stress is more preferably 100 MPa or less.

  The total pressure during film formation is preferably 150 Pa or more and 350 Pa or less. By forming the film at a total pressure of 150 Pa or more and 350 Pa or less, it is possible to form a passivation layer having a coverage of 70% or more, and to control the density while maintaining a low film stress. If the total pressure is less than 150 Pa, it takes a long time to form a required film thickness, and damage due to the film formation temperature is accumulated for a long time in the organic light emitting medium layer, resulting in deterioration of the light emission characteristics. Further, when the pressure is higher than 350 Pa, the coverage is remarkably lowered, and the film formation rate is remarkably lowered due to the increase in the number of molecules in the chamber. The substrate temperature during film formation is preferably 50 ° C. or higher and 90 ° C. or lower. When the temperature is lower than 50 ° C., a by-product during film formation is likely to be generated, and film defects are likely to occur when adhering to the substrate. When the temperature is higher than 90 ° C., the characteristics of the organic electroluminescence panel depend on the temperature during film formation. May deteriorate.

In the passivation layer 15 according to the present invention, the film density is controlled, and conditions for improving the light extraction efficiency and the sealing performance are provided. The light incident on the film is refracted because the speed decreases when entering a high film from a film having a relatively low density. Therefore, a film having a high density has a high refractive index. In addition, the difference in refractive index is large, and light incident on a low film from a high refractive index film is more easily reflected. By preventing this reflection, light emission from the organic electroluminescence panel can be taken out without loss. Common glass substrate has a density of about 1.5 g / m ^3, also the adhesive layer is about 1.2 to 1.3 g / m ^3. On the other hand, a general passivation layer has a film density of about 2.3 to 2.6 g / m ³ , and due to this density difference, reflection at the interface between the passivation layer and the adhesive layer is large, thereby reducing light extraction efficiency. As one of the causes, in the present invention, the density of the passivation layer 15 is controlled so that the film density in the vicinity of the adhesive layer 17 is approximately the same as that of the adhesive layer 17.

Here, a method of forming a film while controlling the film density of the passivation layer 15 will be described. As shown in FIG. 2A, the film density of the passivation layer 15 is mainly proportional to the RF power at the time of film formation, but the stress increases as the power changes under a constant pressure. Therefore, by adjusting the SiH ₄ gas flow rate to 2 to 5 times the NH ₃ gas flow rate, by changing the pressure in the chamber continuously, there is no large density difference, and there is no film interface. Can be formed. In the case of a film having no film interface, reflection at the interface does not occur, and thus light extraction efficiency can be improved when light is extracted from the sealing side. Furthermore, organic electroluminescence panels that extract light from the sealing side, such as the top emission type and the dual emission type, require a passivation layer having a high visible light transmittance, which is at least 85% or more and 90% or more depending on the device. Visible light transmittance is required. In order to maintain the visible light transmittance, the ratio of the SiH ₄ flow rate and the NH ₃ flow rate is important. However, if too much emphasis is placed on the visible light transmittance, the water vapor transmission rate may deteriorate. is there. Therefore, after controlling the film density to a desired value, in order to maintain the water vapor transmission rate, first, the NH ₃ flow rate is increased to increase the film thickness with a film having a high visible light transmittance, and then the desired film density. The flow rate ratio is controlled so that the uppermost layer is a low-density film. Specifically, the film density with respect to RF power and pressure is as shown in FIG. 2A, and the transmittance with respect to the NH ₃ / SiH ₄ flow rate ratio is as shown in FIG. 2B. In the present embodiment, the passivation layer 15 is formed so that the water vapor transmission rate is 0.01 g / m ² · day or less.

Based on the above conditions, a method of forming the passivation layer 15 according to the present invention will be described. In the present invention, the passivation layer 15 is formed by a plasma CVD method using SiH ₄ and NH ₃ . As described above, film formation is performed while controlling the film density. However, film formation is performed such that the film density is maximized at a position in contact with the second electrode layer 14 and gradually decreases. Further, the RF power and the pressure are simultaneously controlled so that the passivation layer 15 does not form a film interface due to a difference in film density from a position in contact with the second electrode layer 14 to a position in contact with the adhesive layer 17. gradually decreasing the film density from 2.5 g / cm ³ with, in a portion in contact with the adhesive layer 17 was formed to a 1.5 g / cm ^3. On the way, when the film density reached about 1.9 g / cm ³ , the film thickness was adjusted to a desired film thickness while controlling the NH ₃ / SiH ₄ to prevent the decrease in transmittance. The film density of the passivation layer 15 is preferably 2.4 g / cm ³ or more at a position in contact with the second electrode layer 14 and is preferably 1.6 g / cm ³ or less at a position in contact with the adhesive layer 17. Thus, by forming the passivation layer 15 whose density gradually changes, the refractive index also changes gradually, and reflection at the interface can be reduced. Further, the density of the passivation layer 15 on the adhesive layer 17 side can be made close to the density of the adhesive layer 17, thereby reducing reflection at the interface between the adhesive layer 17 and the passivation layer 15.

  The total thickness of the passivation layer 15 for the top emission type or double-sided emission type organic electroluminescence panel is preferably 2 μm or less. This is in order to achieve both the adjustment of light interference and sealing performance to make it appear more transparent in consideration of the visibility to structures such as wiring and partition walls generally formed in the organic electroluminescence panel. is there.

Subsequently, an adhesive layer 17 is formed using an adhesive, and a sealing substrate 18 is stacked thereon and sealed. A thermosetting adhesive can also be used as the adhesive layer 17, but a photocurable adhesive is preferable in consideration of the influence on the organic electroluminescence panel. For example, radical adhesives using resins such as ester acrylates, urethane acrylates, epoxy acrylates, melamine acrylates, various acrylates such as acrylic resin acrylates, resins such as urethane polyester, and cations using resins such as epoxy and vinyl ether Examples thereof include cationic adhesives, thiol / ene addition type resin adhesives, etc. Among them, cationic adhesives that are not inhibited by oxygen and that undergo a polymerization reaction even after light irradiation are preferable. As the cationic curable type, an ultraviolet curable epoxy resin adhesive is preferable. Particularly preferred is an ultraviolet curable adhesive that cures within 10 seconds to 90 seconds when irradiated with ultraviolet rays of 100 mW / cm ² or more. By curing within this time range, the ultraviolet curable adhesive can be sufficiently cured and provided with an appropriate adhesive strength without adversely affecting other components due to ultraviolet irradiation. Moreover, it is preferable that it is in the said time range also from a viewpoint of the efficiency of a production process. Regardless of the type of the adhesive layer 17, a material having low moisture permeability and high adhesiveness is desirable. Examples of methods for forming a resin layer on a sealing material include solvent solution method, extrusion lamination method, melting / hot melt method, calendar method, nozzle coating method, screen printing method, vacuum laminating method, hot roll laminating method, etc. Can be mentioned. Although there is no restriction | limiting in particular as the thickness of the contact bonding layer 17, It is preferable that it is a thin layer as much as possible, and is about 1 micrometer-100 micrometers, Preferably it is 5 micrometers-50 micrometers.

  As the sealing substrate 18, a plastic film such as glass, polyethylene terephthalate (PET), polyethersulfone (PES), polyethylene naphthalate (PEN) is used in the case of a top emission type organic EL element that requires transparency. In particular, in the case of a bottom emission type organic EL element that does not require transparency, a metal material such as stainless steel or aluminum, an opaque glass, or a plastic material can be used in addition to the above materials.

In the following, an embodiment for producing the organic electroluminescence panel of the present invention will be described, but the present invention is not limited thereto.
[Example 1]

  The substrate 11 already includes a first electrode layer 12, an extraction electrode, an inorganic insulating layer made of a SiNx layer for protecting the TFT circuit, and a resin insulating layer made of polyimide on the inorganic insulating layer, and the insulating layer partitions the pixels. A TFT substrate formed as the partition wall 28 was used.

  Next, a hole transport layer made of a mixture of poly (3,4 ethylenedioxythiophene) and polystyrene sulfonic acid was formed on the first electrode layer 12 with a thickness of 20 nm by spin coating.

  Next, poly [2-methoxy-5- (2′-ethyl-hexyloxy) -1,4-phenylene burene], which is an organic light emitting material, is dissolved in toluene on the hole transport layer, and organic by spin coating. A light emitting layer was formed, and an organic light emitting medium layer 13 having a thickness of 80 nm was formed together with the hole transport layer.

  Next, the 2nd electrode layer 14 which consists of Ba and ITO was formed by 5 nm thickness and 100 nm thickness by the vapor deposition method and the resistance heating vapor deposition method, respectively.

Subsequently, a passivation layer 15 made of silicon nitride was formed by a plasma CVD method. Deposition was started under the conditions of gas flow rates of SiH ₄ : 80 sccm, NH ₃ : 30 sccm, substrate temperature of 80 degrees, total pressure of 350 Pa, RF power of 2000 W, and the density was gradually reduced from reaching 200 nm thickness. It was. (The gas flow rate is a flow rate standardized at 0 ° C. and 101.3 kPa.) First, when the pressure is simultaneously reduced at a rate of 3 Pa / sec and RF power at a rate of 5 W / sec and reaches 300 Pa and 1200 W, SiH ₄ , The flow rate of NH ₃ was changed at 10 sccm / sec to 200 sccm and 100 sccm. Under these conditions, a film of 500 nm is formed, and then the pressure is simultaneously reduced at a rate of 3 Pa / sec and the RF power is reduced at a rate of 5 W / sec. When 250 Pa and 500 W are reached, the flow rates of SiH ₄ and NH ₃ are 150 sccm at 10 sccm / sec. , 200 sccm, and the reached state was maintained for 15 seconds to complete the film formation.

  Next, an adhesive layer 17 is formed on the passivation layer 15 using an ultraviolet curable adhesive layer, a sealing substrate 18 made of flat glass is bonded, sealed by irradiating 5000 mJ of ultraviolet light, and an organic electroluminescence panel It was created.

As a result of applying a voltage of 7 V to the organic electroluminescence panel thus obtained, a luminance of 3000 cd / m ² was obtained and the current efficiency was 6 cd / A. Further, no non-light emitting pixels were observed, but dark spots were observed at 5 pixels when observed with a microscope. Further, when it was allowed to stand for 1500 hours at 60 ° C. and 90% RH, the number of non-light emitting pixels was not observed, and no expansion of dark spots was observed.
[Comparative Example 1]

The passivation layer 15 of Example 1 was formed to a thickness of 1000 nm under the conditions of gas flow rates of SiH ₄ : 80 sccm, NH ₃ : 30 sccm, substrate temperature of 80 degrees, total pressure of 350 Pa, RF power of 2000 W, and further 300 Pa, 1200 W, SiH _4. An organic electroluminescence panel having a film thickness of 200 sccm and 100 sccm at a flow rate of NH ₃ of 10 sccm / sec was prepared. As a result of applying a voltage of 7 V to the organic electroluminescence panel thus obtained, the luminance was 2400 cd / m ² and the current efficiency was also reduced to 4.7 cd / A. Further, when left at 60 ° C. and 90% RH, the dark spot enlargement expanded at 900 hours, and after 1000 hours, the dark spots were seen up to the adjacent pixels and at 8 pixels.

  The present invention can be used for flat panel displays, lighting, and the like used in televisions, personal computer monitors, mobile devices, and the like.

DESCRIPTION OF SYMBOLS 11 ... Board | substrate 12 ... 1st electrode layer 13 ... Organic luminescent medium layer 14 ... 2nd electrode layer 15 ... Passivation layer 16 ... Partition 17 ... Adhesion layer 18 ... Sealing substrate 21 ... Substrate 22 ... 1st electrode layer 23 ... Organic light emission Medium layer 24 ... second electrode layer 25 ... adhesive layer 26 ... desiccant 27 ... sealing substrate

Claims (5)

A top emission type or dual emission type organic electroluminescence panel comprising at least a first electrode layer, an organic light emitting medium layer including an organic light emitting layer, a second electrode layer, a passivation layer, and an adhesive layer in this order on a substrate. And
The passivation layer contains at least silicon nitride and has a film density of 2.4 g / cm ³ or more in contact with the second electrode layer, and the density gradually decreases toward the adhesive layer. The organic electroluminescent panel characterized by being 1.6 g / cm < ³ > or less in the contact | connecting location.   2. The organic electroluminescence panel according to claim 1, wherein the passivation layer does not have an interface due to a density difference from a position in contact with the second electrode layer to a position in contact with the adhesive layer.   3. The organic electroluminescence panel according to claim 1, wherein the light transmittance in the visible light region of the passivation layer is 90% or more. 4. 4. The organic electroluminescence panel according to claim 1, wherein the water vapor permeability of the passivation layer is 0.01 g / m ² · day or less.   5. The organic electroluminescence panel according to claim 1, wherein the total thickness of the passivation layer is 2 μm or less.

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