JP2008153004A - Organic electroluminescence device - Google Patents

Abstract

An object of the present invention is to provide a durable film sealed with a sealing film that is a dense film, has a low possibility of cracking, is thin and has high barrier properties, has low stress, and can be manufactured by a simple method in terms of tact and production process. It is to obtain an organic EL element having high performance.
An organic electroluminescent layer comprising a first electrode, one or more organic compound films including a light emitting layer formed on the first electrode, a second electrode, and a second electrode on the substrate. In the organic electroluminescent element in which the sealing film having the unit composed of three layers of the first, second, and third inorganic films composed of at least silicon, nitrogen, and oxygen is formed, the first and third inorganic films When the nitrogen and oxygen components are observed in terms of atomic concentration, the amount of the components is large in the order of nitrogen and oxygen, and when the nitrogen and oxygen components of the second inorganic film are viewed in atomic concentration, the amounts of oxygen and nitrogen are in this order. Organic electroluminescence device with a large amount of components.
[Selection] Figure 1

Description

  The present invention relates to an organic electroluminescence element sealed with a thin film having a barrier property and a method for producing the same.

  An organic electroluminescence (EL) element is a surface light emitting element capable of emitting light with high luminance from blue to red at a low voltage.

  However, when the organic EL device is driven for a certain period, there is a problem in that non-light emitting portions called dark spots are generated and grown, and the light emission characteristics deteriorate.

  Such dark spots are said to have the greatest influence of moisture such as water vapor and oxygen, and it is necessary to seal the organic EL element to shield the influence of moisture and oxygen (barrier properties). Devices incorporating films are being considered.

  In general, an inorganic film having a high barrier property when used as a sealing film preferably has a high density, but such a film tends to be hard, brittle, and high in film stress. For this reason, when the film is thickened, the stress tends to increase and cracks tend to occur.

  For example, in patent document 1, in order to ensure barrier property with a single film, an inorganic film of 2 μm is attached. In this example, since the film has a small residual stress, there is a problem in barrier properties, and a relatively thick film is formed as an inorganic film. However, it is currently difficult to block moisture with an inorganic single film.

  Patent Document 2 describes forming a resin sealing film of 1 to 10 μm between inorganic sealing films of 1 μm or more. Similarly, in this example, it is difficult to form a dense film with low stress, which is contrary to reality. In order to ensure barrier properties, the inorganic film is formed relatively thick. In addition, it is described that by forming a resin film between double inorganic films, it can provide coverage against foreign matters causing inorganic film defects and a double blocking effect of inorganic film defects, and can ensure high barrier properties. . However, the inorganic film is formed by a vacuum process, and the resin film is formed using a method such as a coating process or a laminate. Therefore, the process is complicated and has problems in terms of cost and productivity.

In the present invention, even if a dense film having a high barrier property is formed, the possibility of cracking is low, and a sealing film made of an inorganic film having a low barrier property and low stress can be realized even if it is thin as a whole. A simple method can also be provided in terms of the production process.
JP 2000-223264 A JP 2004-79291 A

  Therefore, an object of the present invention is to provide a sealing film that is a dense film, has a low possibility of cracking, is thin, has high barrier properties, has low stress, and can be manufactured by a simple method in terms of tact and production processes. The object is to obtain a sealed and highly durable organic EL element.

  The above object of the present invention is achieved by the following means.

1. On the substrate, the first electrode, an organic electroluminescent layer composed of one or more organic compound films including a light emitting layer formed on the first electrode, the second electrode, and further on the second electrode,
In an organic electroluminescent element in which a sealing film having at least one unit composed of three layers of a first inorganic film, a second inorganic film, and a third inorganic film composed of at least silicon, nitrogen, and oxygen is formed. 1. When the nitrogen and oxygen components of the third inorganic film are observed in terms of atomic number concentration, the amount of the components increases in the order of nitrogen and oxygen, and when the nitrogen and oxygen components of the second inorganic film are viewed in atomic number concentration An organic electroluminescence device characterized in that the amount of components increases in the order of oxygen and nitrogen.

  2. 2. The organic electroluminescence device according to 1 above, wherein the first inorganic film is thinner than the third inorganic film.

  3. 3. The organic electroluminescence device according to 1 or 2, wherein the second inorganic film is thicker than the third inorganic film.

  4). 4. The organic electroluminescence element according to any one of 1 to 3, wherein the first inorganic film has a thickness of 20 to 70 nm.

  An organic electroluminescence (EL) element with less generation of dark spots and the like having good durability over a long period of time can be obtained.

  Hereinafter, the best mode for carrying out the present invention will be described.

  The present invention provides a substrate having a first electrode, an organic EL layer composed of one or more organic compound thin films including a light emitting layer formed on the first electrode, a second electrode, and a water having a sealing film. The present invention relates to an organic EL element sealed from a harmful gas such as oxygen.

The sealing film is a sealing film having at least one unit composed of three layers of a first inorganic film, a second inorganic film, and a third inorganic film composed of at least silicon, nitrogen, and oxygen,
The first and third inorganic films in the sealing film are films in which the nitrogen and oxygen components have a large amount of components in the order of nitrogen and oxygen when viewed in atomic concentration.
The second inorganic film is a film having a large amount of components in the order of nitrogen and oxygen components in the order of oxygen and nitrogen. The first and third inorganic films are barrier films that block harmful gases such as water vapor and oxygen, and the second inorganic film constitutes a stress relaxation film.

  In the present invention, the inorganic film composed of at least silicon, nitrogen or oxygen means 98% or more when the sum of the constituent components of silicon, nitrogen and oxygen is viewed in terms of atomic number concentration. More preferably, the sum of the constituent components of silicon, nitrogen, and oxygen is 99.5% or more in terms of the atomic number concentration, and it is most desirable that it is composed only of silicon, nitrogen, and oxygen (that is, the atomic number concentration is 100%). However, even if other elements such as C (carbon) are contained in some amount, the performance is slightly lowered, but a level of practically no problem is obtained.

  FIG. 1 shows an example of the configuration of an organic EL element and a sealing film according to the present invention.

  On an organic EL structure in which a first electrode (for example, an anode) 2, an organic EL layer 3 made of an organic compound thin film including a light emitting layer, and a second electrode (for example, a cathode) 4 are formed on a substrate 1, silicon, nitrogen, oxygen A sealing film having a configuration composed of the first inorganic film 5, the second inorganic film 6, and the third inorganic film 7 is formed.

  In FIG. 1, the sealing film has a three-layer structure, and the first and third inorganic films are films having a high barrier property, and the second inorganic film is a stress relaxation film. Moreover, the structure which has two or more of these three-layer units, ie, the structure of 5 layers, 7 layers, etc. may be sufficient. FIG. 2 shows an example of a configuration composed of a total of five layers having a second inorganic film and a third inorganic film on the third inorganic film.

  In the figure, a protective film member 9 for preventing scratches and the like is shown together with the adhesive layer 8. When there is no problem such as contact from the outside, it is not necessary to use a protective film.

  As a sealing film formed on the second electrode, first, a first inorganic film is formed. The first inorganic film and the third inorganic film are silicon oxynitride thin films having a high barrier property and a high nitrogen component. Among these, the first inorganic film is preferably thinner than the third inorganic film. The sealing film has a sufficient thickness through the first inorganic film having a thin barrier property so that the film stress is not so high and the second inorganic film as a more flexible stress relaxation film. The structure which laminated | stacked is taken. As a result, a sealing film having a high barrier property with less damage to the element and less cracking can be obtained.

  Although a silicon oxynitride thin film containing a large amount of nitrogen has high barrier properties, a certain degree of film thickness is required to obtain sufficient barrier properties. A single thick film has high film stress and is likely to generate cracks. End up. In the present invention, a barrier film is divided into a plurality of layers, and a stress relaxation film having a composition similar to that between the barrier films is interposed, thereby generating a sealing film with less cracking and good barrier properties. is there.

  The first inorganic film is thinner than the third inorganic film so that the film stress is not so high, but the thickness is particularly preferably in the range of 20 to 70 nm. When the film thickness is 20 nm or more, sufficient film formation is performed, and when the film thickness is thinner than 70 nm, the film stress is lower, so that the occurrence of initial damage and the occurrence of fine defects is less, and the barrier characteristics at the time of the laminated film are further improved. To do.

  In the present invention, the first inorganic film, the third inorganic film, which are barrier thin films constituting the sealing film, and the second inorganic film, which is a stress relaxation film, are all made of an inorganic film made of silicon, nitrogen or oxygen. It has become.

  The first inorganic film and the third inorganic film are composed of silicon, nitrogen, and oxygen, and are films having a large amount of nitrogen components when viewed in terms of atomic number concentration compared to oxygen when viewed in atomic number concentration. As the nitrogen component increases, the barrier property increases, and the single film has a high elastic modulus and a high film stress. However, the above-described configuration makes it difficult to generate cracks and the like.

In the present invention, the barrier thin film is a film made of an inorganic material having a water vapor transmission coefficient of 1.0 × 10 ⁻¹⁴ g · cm / (cm ² · sec · Pa) or less at 25 ° C.

The water vapor transmission coefficient is measured by the following method. The inorganic barrier film is formed with a predetermined thickness on a support having a known water vapor transmission coefficient (for example, cellulose triacetate film; thickness 100 μm) and used as a sample film as it is, and the primary side and the secondary side separated by sandwiching the sample film Vacuum the two containers. Water vapor with a relative humidity of 90% is introduced into the primary side, and the amount of water vapor (or pressure change) that has permeated the sample membrane and exited to the secondary side is measured at 25 ° C. using a vacuum gauge. This is measured over time, and a transmission curve is created by taking the secondary water vapor pressure (Pa) on the vertical axis and time (seconds) on the horizontal axis. The water vapor transmission coefficient (g · cm · cm ⁻² · sec ⁻¹ · Pa ⁻¹ ) is determined using the slope of the linear portion of this permeation curve. Since the water vapor transmission coefficient of the support is known, the water vapor transmission coefficient of the membrane material can be calculated from this thickness and the thickness of the inorganic barrier film formed on the support.

  A film having a small water vapor transmission coefficient simultaneously forms a thin film having high oxygen permeability.

  In the present invention, the second inorganic film serving as the stress relaxation film has a composition similar to that of the first and third inorganic films, and is also an inorganic film composed of silicon, nitrogen, and oxygen. Contrary to the third inorganic film, it is a film having a larger oxygen component than nitrogen when viewed in terms of atomic number concentration. As a result, the second inorganic film is less dense and barrier property than the silicon oxynitride thin film containing a large amount of nitrogen, which is the first and third inorganic films, but has low elasticity and low stress. An inorganic thin film is formed.

  In order to have a sufficient stress relaxation action between the first and third inorganic films, the second inorganic film is preferably an inorganic material film having an elastic modulus in the range of 20 to 100 GPa. More preferably, it is the range of 40 GPa-100 GPa.

  Incidentally, the first and third inorganic films have a higher modulus of elasticity of 105 to 180 Gpa, preferably 110 to 140 Gpa.

  In the present invention, the elastic modulus is a nanoindentation elastic modulus (Er) measured by the following method.

  The nanoindentation elastic modulus (Er) of the inorganic stress relaxation layer according to the present invention was measured using a scanning probe microscope SPI3800N manufactured by SII Nanotechnology.

  As the indenter, a triangular pyramid-shaped diamond indenter called a Belkovic indenter (tip ridge angle 142.3 °) was used.

  The triangular pyramid-shaped diamond indenter was applied to the sample surface at a right angle, a load was gradually applied, and the load was gradually returned to 0 after reaching the maximum load. A value P / A obtained by dividing the maximum load P at this time by the projected area A of the indenter contact portion was calculated as nanoindentation hardness (H). The nanoindentation elastic modulus (Er) was calculated using the following formula, assuming the slope S of the unloading curve.

(formula)
Er = (S × √π) / (2√A) (π is the circumference)
In addition, it calibrated and measured beforehand the measurement apparatus so that the hardness obtained as a result of pushing the attached fused silica as the standard sample would be 9.5 ± 1.5 GPa.

  Details of the principle are described in Handbook of Micro / Nano Tribology (CRC edited by Bharat Bhushan).

  As a measurement sample, a drop of adhesive Aron Alpha (registered trademark) manufactured by Toagosei Co., Ltd. was dropped on a slide glass, and then the sample cut into about 1 cm square was placed and allowed to stand for 24 hours to be cured.

  The maximum load P was set in advance so that the maximum depth was 15 nm (50 μN). Load and unload in 5 seconds.

  In addition, the stress relaxation film preferably has a predetermined thickness. In particular, in the sealing film according to the present invention, which is an inorganic film laminate, a sufficient stress relaxation film is provided between the first and third inorganic films. In this case, the second inorganic film is preferably thicker than the third inorganic film. The film thickness is 1.4 times or more, more preferably 2 times or more. Moreover, 10 times or less, Furthermore, 5 times or less are preferable.

  Further, although the first and third inorganic films and the second inorganic film are composed of the same component although the component composition ratio is different, the adhesion between the films is high, and there is little fear of peeling and cracking between the films.

  In addition, since a double barrier thin film is formed, even if a fine defect occurs during the formation of the inorganic film, the path is blocked by the double barrier thin film via the stress relaxation film. The high barrier property desired for the element is ensured, and as a single film, even a film having a high film stress has a low stress as a whole film, and does not damage the element, for example, an external environment change, for example, a temperature change There is no need to worry about cracks.

  As described above, in the organic EL element of the present invention, the sealing film includes the first inorganic film that is a barrier thin film, and the second inorganic film that has a similar composition and that has a stress relaxation property, and the third inorganic film. And laminated. A barrier sealing film with little deterioration due to cracks, etc., which cannot be obtained with a barrier inorganic single film by lamination, can be formed, and since the sealing film is composed of a laminated film having a similar composition, the sealing film is the same manufacturing equipment It can be manufactured and has tact and cost advantages.

  In the present invention, the first and third inorganic films are barrier thin films as described above, and are composed of silicon, nitrogen, and oxygen. When viewed in terms of atomic number concentration, among nitrogen and oxygen components, nitrogen, It is a thin film with many components in the order of oxygen. When the nitrogen component is increased, a dense film with high hardness is obtained, so that the barrier property is high, but the internal stress is large and the surface becomes brittle.

  The components of the second inorganic film are also composed of silicon, nitrogen, and oxygen. However, the composition ratios are different from those of the first and third inorganic films. It is an inorganic film having a large amount of components in the order of nitrogen. That is, so-called silicon oxide, silicon nitride oxide, which has a higher proportion of oxygen component than nitrogen, has a lower internal stress and a lower elastic modulus as described above, cracks, etc. A flexible thin film is formed that is less likely to cause the problem.

  The atomic concentration% of the silicon oxynitride film can be obtained by using a known analysis means. In the present invention, it is calculated by the following XPS method, and the atomic concentration (atomic concentration) defined below is used. : At%).

Atomic concentration = number of atoms / number of all atoms × 100
As the XPS surface analyzer, ESCALAB-200R manufactured by VG Scientific, Inc. is used in the present invention. Specifically, Mg is used for the X-ray anode, and measurement is performed at an output of 600 W (acceleration voltage: 15 kV, emission current: 40 mA). The energy resolution is set to be 1.5 eV to 1.7 eV when defined by the half width of a clean Ag3d5 / 2 peak.

  As the measurement, first, the range of the binding energy of 0 eV to 1100 eV is measured at a data acquisition interval of 1.0 eV to determine what elements are detected.

  Next, with respect to all the detected elements except the etching ion species, the data acquisition interval is set to 0.2 eV, and the photoelectron peak giving the maximum intensity is narrow-scanned to measure the spectrum of each element (in this case) Silicon, nitrogen, oxygen).

  The obtained spectrum is COMMON DATA PROCESSING SYSTEM manufactured by VAMAS-SCA-JAPAN (preferably Ver. 2.3 or later) so as not to cause a difference in the content calculation result due to a difference in measuring apparatus or computer. After being transferred to the top, it is processed with the same software, and the content value of the element (oxygen, nitrogen, silicon, etc.) of the analysis target is obtained.

  Before performing the quantitative process, the calibration of the count scale is performed for each element, and the 5-point smoothing process is performed. In the quantitative processing, the peak area intensity (cps × eV) from which the background is removed is used. For background processing, a method by Shirley is used. For the Shirley method, see D.C. A. Shirley, Phys. Rev. , B5, 4709 (1972).

  Examples of the method for forming the first and third inorganic films and the second inorganic film include a plasma CVD method, a sputtering method, and an ion plating method. In the case of the first and third inorganic films, Any method can be used as long as it has a low water vapor transmission rate (coefficient) and can form a dense film with low film stress, and is not limited thereto.

  For example, in the case of forming a thin film by a sputtering method, a difference occurs in the degree of filling of the formed film and its composition depending on the manufacturing conditions, the types and ratios of the reaction gas and additive gas used.

When silicon oxynitride (SiO _x N _y ) is formed using a sputtering method, for example, a magnetron sputtering apparatus with silicon as a target, a reactive gas, N ₂ (nitrogen) or O ₂ (oxygen) gas, is used. By controlling these flow rates, silicon nitride or a silicon oxynitride thin film having a desired nitrogen-oxygen ratio can be formed by controlling the composition. If the nitrogen ratio of the reactive gas is increased, a barrier thin film having a high silicon nitride content is formed. Conversely, if the oxygen ratio is increased, a thin film having a low elastic modulus is formed.

In the plasma CVD method, SiH ₄ (silane) gas, NH ₃ (ammonia), N ₂ O (nitrous oxide), N ₂ (nitrogen), and O ₂ (oxygen) gas are used as source gases. A thin film made of silicon, oxygen, and nitrogen can be formed, but the film composition is changed by controlling the flow rates of nitrogen and oxygen, and the first and third inorganic films having barrier properties and the second inorganic film that becomes the stress relaxation film Can be produced respectively.

In the case of the plasma CVD method, for example, only SiH ₄ (silane) gas and N ₂ (nitrogen) gas are used, and each flow rate is 10 sccm, 200 sccm, RF power is 10 W, chamber internal temperature is 120 ° C., and pressure is 120 Pa. Thus, a silicon nitride film having a small oxygen content can be obtained. In order to form a film having a higher oxygen content, O ₂ (oxygen) gas is introduced.

  As described above, the first inorganic film, the second inorganic film, and the third inorganic film can be continuously formed and stacked using the same apparatus by simply changing the conditions such as the gas flow rate. .

  In the present invention, the first inorganic film and the second inorganic film having the barrier property and the second inorganic film to be the stress relaxation film are respectively laminated and formed in a predetermined order to form the sealing film. When forming the film and the third inorganic film, for example, when forming the second inorganic film from the first inorganic film, the gas introduction amount of the film forming apparatus is continuously changed from the condition of the first inorganic film to the condition of the second inorganic film. When the first inorganic film forming apparatus and the second inorganic film forming apparatus are continuously connected to form a film by passing between the film forming apparatuses, the first inorganic film and the second inorganic film forming apparatus An inorganic film may be continuously formed as an inclined layer. Also in this case, the same effect as that of the present invention can be expected. In this case, the ratio of the atomic number concentration of the inclined layer of the first inorganic film and the second inorganic film is a boundary point between the first inorganic film and the second inorganic film. Think about it. Further, the inclined section is preferably 10% or less of the inorganic film thickness in contact therewith.

  The sealing film in the organic EL element of the present invention has been described above. Next, the configuration of the organic EL element of the present invention will be described.

  As shown in FIG. 1, the organic EL element of the present invention is formed by laminating a first electrode (anode) 2, an organic EL layer 3, and a cathode 4 on a substrate, and further on the first inorganic film, The second inorganic film or the third inorganic film is laminated to form a sealing film.

  Next, the organic EL layer and its constituent components of the organic EL device according to the present invention will be described.

  In the organic EL element, when a positive voltage is applied to the anode and a negative voltage is applied to the cathode, the injected electrons and holes are recombined in the light emitting layer in the organic EL layer to emit light. The organic EL element is most simply composed of an anode / light emitting layer / cathode. For example, the structure of the anode / hole transport layer / light emitting layer / electron transport layer / cathode, etc. The hole injection layer, electron blocking layer, hole blocking layer, electron injection layer, buffer layer, and other necessary layers are stacked in the specified layer order, so that carriers such as holes and electrons injected from both electrodes are efficiently transferred. Some are configured to do well.

  In FIG. 1, the first electrode (anode) 2, the organic EL layer 3, and the second electrode (cathode) 4 are stacked in this order on the substrate 1, but conversely, the first electrode on the substrate 1. 2, the cathode may be further formed as an organic EL layer, and the order of the layers may be reversed, and the anode may be stacked as the second electrode 4 in order.

  As the substrate 1, a transparent glass substrate such as soda lime glass or non-alkali glass, a transparent plastic substrate typified by polyethylene terephthalate, polycarbonate, or the like can be used.

As the anode, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function is preferably used, and an electrode material having a work function of 4 eV or more is particularly preferable. Specific examples of such electrode materials include metals such as gold, conductive transparent materials such as CuI, ITO (indium tin oxide), IZO, SnO ₂ , and ZnO. For example, the anode can be formed as a thin film by depositing these electrode materials on the substrate 1 by a method such as a vacuum deposition method, an ion plating method, or a sputtering method.

  In the case where a transparent glass substrate is used as the substrate 1 and an anode is laminated as the first electrode 2 and light is transmitted through the anode through the substrate 1, the light transmittance of the anode is preferably 10% or more. The sheet resistance of the anode is preferably several hundred Ω / □ or less, particularly preferably 100 Ω / □ or less. Furthermore, the film thickness of the anode varies depending on the material in order to control the characteristics such as light transmittance and sheet resistance of the anode as described above, but is usually preferably 500 nm or less, and more preferably in the range of 10 to 200 nm.

On the other hand, in the organic EL layer 3, a cathode (for example, the second electrode 4) that is an electrode for injecting electrons into the light emitting layer is an electrode made of a metal, an alloy, an electrically conductive compound, and a mixture thereof having a low work function. It is preferable to use a material, and as such an electrode material, sodium, sodium-potassium alloy, lithium, magnesium, aluminum, magnesium-silver mixture, magnesium-indium mixture, aluminum-lithium alloy, Al / Al ₂ O ₃ mixture And Al / LiF mixtures. The cathode can be produced by forming these electrode materials into a thin film by a method such as vacuum deposition or sputtering. Further, when light emission is transmitted through the cathode and taken out to the outside, the cathode preferably has a light transmittance of 10% or more. Although the film thickness of the cathode 4 varies depending on the material, it is usually preferably 500 nm or less, and more preferably in the range of 100 to 200 nm.

  Organic light-emitting materials contained in the light-emitting layer include aromatic heterocyclic compounds such as carbazole, carboline, diazacarbazole, triarylamine derivatives, stilbene derivatives, polyarylene, aromatic condensed polycyclic compounds, and aromatic heterocondensed compounds. Examples thereof include, but are not limited to, a ring compound, a metal complex compound and the like, and a single oligo compound or a composite oligo compound thereof.

  The light emitting layer preferably contains about 0.1 to 20% by mass of a dopant in the light emitting material. Examples of the dopant include known fluorescent dyes such as perylene derivatives and pyrene derivatives, and in the case of phosphorescent light emitting layers, for example, tris (2-phenylpyridine) iridium, bis (2-phenylpyridine) (acetylacetonate). And complex compounds such as ortho-metalated iridium complexes represented by iridium, bis (2,4-difluorophenylpyridine) (picolinato) iridium, and the like. The thickness of the light emitting layer is preferably 0.5 to 500 nm, particularly preferably 0.5 to 200 nm.

  As the hole injection / transport layer, conductive polymers represented by phthalocyanine derivatives, heterocyclic azoles, aromatic tertiary amines, polyvinyl carbazole, polyethylenedioxythiophene / polystyrene sulfonic acid (PEDOT: PSS), etc. In addition, for example, carbazole-based light-emitting materials such as 4,4′-dicarbazolylbiphenyl and 1,3-dicarbazolylbenzene, (di) azacarbazoles, , 3,5-tripyrenylbenzene, and the like, and low molecular light emitting materials typified by pyrene-based luminescent materials, polyphenylene vinylenes, polyfluorenes, polyvinyl carbazoles, and the like.

  Examples of the electron injection / transport layer material include metal complex compounds such as 8-hydroxyquinolinate lithium and bis (8-hydroxyquinolinate) zinc, and nitrogen-containing five-membered ring derivatives listed below. That is, oxazole, thiazole, oxadiazole, thiadiazole or triazole derivatives are preferred. Specifically, 2,5-bis (1-phenyl) -1,3,4-oxazole, 2,5-bis (1-phenyl) -1,3,4-thiazole, 2,5-bis (1 -Phenyl) -1,3,4-oxadiazole, 2- (4′-tert-butylphenyl) -5- (4 ″ -biphenyl) 1,3,4-oxadiazole, 2,5-bis ( 1-naphthyl) -1,3,4-oxadiazole, 1,4-bis [2- (5-phenyloxadiazolyl)] benzene, 1,4-bis [2- (5-phenyloxadiazolyl) -4-tert-butylbenzene], 2- (4'-tert-butylphenyl) -5- (4 "-biphenyl) -1,3,4-thiadiazole, 2,5-bis (1-naphthyl) -1 , 3,4-thiadiazole, 1,4-bis [2- (5-phenyl) Asiazolyl)] benzene, 2- (4′-tert-butylphenyl) -5- (4 ″ -biphenyl) -1,3,4-triazole, 2,5-bis (1-naphthyl) -1,3,4 -Triazole, 1,4-bis [2- (5-phenyltriazolyl)] benzene and the like.

  In the organic EL layer, the thickness of each organic layer needs to be about 0.05 to 0.3 μm, and preferably about 0.1 to 0.2 μm.

  In the embodiment shown in FIG. 1, a first electrode 2, an organic EL layer 3 including a hole transport layer, a light emitting layer, an electron transport layer, and the like, and a second electrode 4 are formed on a substrate 1. A first inorganic film 5 having a barrier property is provided on the second electrode of the laminate. The first inorganic film 5 is formed so as to cover the entire surface of the second electrode. In FIG. 1, the organic EL layer 3 and the second electrode 4 other than the upper surface of the second electrode 4 and the extraction portion of the first electrode 2 are formed. The first electrode 2 and the second electrode 4 are exposed so as to cover the side surfaces (end surfaces) of the first electrode 2 and the second electrode 4. A second inorganic film 6 is provided on the first inorganic film 5, and a third inorganic film 7 is further provided thereon. The second inorganic film 6 is preferably provided so as to cover the side surface (end face) of the first inorganic film 5, and the third inorganic film is also provided so as to cover the side face (end face) of the stress relaxation film. It is preferable for obtaining the effect.

  In FIG. 1, a protective resin film member 9 is further provided on the second inorganic film via an adhesive layer 8 to protect against scratches and the like due to external force so as to cover the entire outer surface of the second inorganic film 7. Are stacked. As the protective resin film member, a plastic film made of a resin such as polyethylene terephthalate, polyethylene naphthalate or polycarbonate, or a plastic film made of a heat resistant resin such as polyethersulfone or polyimide is preferable. Of these, a plastic film made of polyethylene terephthalate is preferable.

  By providing such a protective resin film member 9, the influence of moisture from the outside can be further blocked. As the adhesive layer 8 for bonding the protective resin film member, a UV curable adhesive composition made of an acrylic resin, an epoxy resin, a fluorine resin, or the like can be used. For example, Nagase Chemtech A UV curable adhesive (resin) such as UV Resin XNR5516 manufactured by Co., Ltd. can be used. Of course, a heat bonding resin may be used.

  The thickness of the protective resin film member 9 is not particularly limited, but is preferably set in the range of 10 to 500 μm in view of the balance between the protective performance of the film and the film stress.

  Furthermore, it is preferable to use a film having a high barrier property such as a metal laminate film or an alumina vapor deposition film as the protective resin film member because the barrier property is further improved.

  In the organic EL device according to the present invention, it is preferable that the process up to the formation of the sealing film can be performed consistently by a vacuum process. Since the bonding process of the protective resin film member is not necessarily performed under vacuum, it is preferably performed under an inert gas atmosphere for deoxidation and dehydration, for example, under nitrogen.

  As described above, the organic EL device according to the present invention can be carried out consistently through the vacuum process until the formation of the sealing film. Therefore, there is no complication, and a simple method in terms of tact time and production process can be used. A high organic EL element can be obtained.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

<< Production of organic EL element >>
Example 1
Using a glass substrate with ITO (100 nm thickness) having a thickness of 100 × 100 mm and a thickness of 1.0 mm, ITO was patterned to form an anode and an anode terminal portion.

Next, the substrate on which the anode was formed was fixed to a substrate holder of a commercially available vacuum deposition apparatus, and each of the constituent materials of each layer of the organic EL layer was filled in each of the deposition crucibles in the vacuum deposition apparatus. Deposition was performed under reduced pressure to a vacuum degree of 4 × 10 ⁻⁴ Pa and rotating around the center of the substrate through a shadow metal mask covering the substrate other than the anode terminal portion and the light emitting region.

  The following organic layers were sequentially laminated.

Hole injection layer (PEDOT: 40 nm) / hole transport layer (α-NPD: 20 nm) / light emitting layer (CBP, Ir (ppy) ₃ (6%): 30 nm) / hole blocking layer (BAlq: 10 nm) / Electron transport layer (Alq ₃ : 30 nm) / LiF (0.5 nm)
PEDOT: PEDOT / PSS, manufactured by Bayer, Baytron P Al 4083
Furthermore, the cathode (thickness 150 nm) and cathode terminal part (cathode feeding part) which consist of aluminum were formed by vapor deposition.

<Sealing work>
<Preparation of sealing film>
As shown in FIG. 1, a sealing film was produced.

The organic EL device produced as described above was placed in a sputtering chamber while maintaining a vacuum. For sputtering, a silicon target was used, and a DC magnetron sputtering apparatus using a pulse power source was used. A DC power source was used as the power source, and an output having a maximum of 1 kW was used. The discharge gas uses argon, and N ₂ and O ₂ can be introduced as reaction gases in order to form a SiOxNy film.

  As shown in Table 1, the first inorganic film, the second inorganic film, and the third inorganic film were formed under the following gas conditions.

That is, a first inorganic barrier film is formed under a condition where the N ₂ gas flow rate is high, a second inorganic film is formed under a condition where the O ₂ gas flow rate is increased, and a third inorganic film is formed under the same conditions as the first inorganic barrier film. Formed.

  The thickness of each of the first inorganic film, the second inorganic film, and the third inorganic film was changed as shown in Table 1 to obtain a sealing film.

First inorganic film: base pressure 2 × 10 ⁻⁴ Pa
Argon 40sccm
Nitrogen 25sccm
Oxygen 1sccm
Thickness Table 1 Second inorganic film: Base pressure 2 × 10 ⁻⁴ Pa
Argon 40sccm
Nitrogen 10sccm
Oxygen 20sccm
Thickness described in Table 1 Third inorganic film: base pressure 2 × 10 ⁻⁴ Pa
Argon 40sccm
Nitrogen 25sccm
Oxygen 1sccm
Thickness described in Table 1 The film formation rate at this time was 0.5 nm / sec to 1 nm / sec. The thickness conditions of each inorganic film are as shown in Table 1 below. The base pressure indicates the film forming chamber pressure before introducing the gas.

  In addition, when the composition of the 1st, 3rd inorganic film and the 2nd inorganic film was measured using XPS surface analyzer VG Scientific company ESCALAB-200R, the number of atoms of both the 1st inorganic film and the 3rd inorganic film The concentrations were Si (44%), O (21%), and N (35%), and the second inorganic film was a film of Si (41%), O (48%), and N (11%).

In addition, about the 1st inorganic film or the 3rd inorganic film, when the water vapor transmission coefficient was measured by the above-mentioned method, all were 25 * C, and the water vapor transmission coefficient was 1.0 * 10 < ^-14 > g * cm / (cm < ² > *). sec · Pa) or less.

  The second inorganic film had a nanoindentation elastic modulus (Er) and a value of 75 Gpa. Incidentally, the elastic modulus of the first and third inorganic films was 125 Gpa.

After forming the sealing film, the film was transferred under an inert gas (N ₂ environment), and the protective film member was attached.

<Arrangement of protective film member for preventing external scratches>
The organic EL element with the film sealed is made of a polyethylene terephthalate film with a hard coat, which is a protective film member corresponding to the light emitting part and the outer peripheral surface, except for the terminal part (external extraction electrode) of the anode and cathode of the organic EL element. An adhesive was placed on the film member surface at a thickness of 0.1 mm by screen printing. As the adhesive, UV resin XNR5516 manufactured by Nagase Chemtech Co., Ltd. was used.

Thereafter, a flexible sealing member with an adhesive is superposed on the organic EL element, and then the flexible sealing member is pressure-bonded and bonded, and a handy high-pressure mercury lamp (OHD-110M-ST manufactured by Oak Manufacturing Co., Ltd.). ) To give an irradiation energy of 6000 mJ / cm ² or more, followed by curing, and an organic EL device covered and sealed with a protective film member was produced. The adhesive may be a thermosetting type.

  In this example, the protective film material is disposed. However, when there is no problem such as contact from the outside, the protective film may not be used.

(Evaluation)
A voltage of 5 V was applied to the obtained organic EL element to emit light. Next, after storing each organic EL device under accelerated deterioration conditions (60 ° C., 90% RH, 500 hours), the light is emitted in the same manner, and the area of the light emitting portion excluding the non-light emitting portion such as a dark spot is the ratio of the initial light emitting area. The notation. If it is more than △, it can be said that it can be used.

A: 95% or more (~ 100%)
○: 90% or more, less than 95% △: 85% or more, less than 90% ×: less than 85%

  When the thickness of the first inorganic film of the first layer is small, it becomes close to a single film, and when the performance exceeds 80 nm, the dark spots slightly increase. It can be seen that the film imparts good sealing properties to the organic EL element.

Example 2
In Example 1 (the film thickness conditions were the same as those of Sample 3), the same procedure as in Example 1 was performed except that the sealing film was produced by changing the sputtering conditions (gas introduction amount) of each layer of the sealing film. Organic EL elements 8 to 16 were produced. Table 2 shows the composition of the produced sealing film as seen from the atomic number concentration of each of the first inorganic film, the second inorganic film, and the third inorganic film. When the same evaluation as Example 1 was performed about the organic EL element sealed by each sealing film, the following results were obtained.

  In addition, the composition of each inorganic film in the sealing film is indicated by the atomic number concentration measured using an ESCLAB-200R manufactured by XPS surface analyzer VG Scientific.

  Various silicon oxynitride films having a composition containing more nitrogen than oxygen are used as the first and third inorganic films, and a silicon oxynitride film having a composition containing more oxygen than nitrogen is used as the stress relaxation film. The organic EL element sealed with the sealing film used in the above has a good sealing property with few dark spots.

  Further, in the organic EL element condition 12, when the above evaluation was performed when 1.5% carbon was mixed into the second inorganic film and when 1.0% carbon was mixed into the first inorganic film, The performance is slightly lower than the case where there is no mark and no contamination, but a level of performance that is practically acceptable is obtained. Moreover, when 2.1% carbon was mixed in the first inorganic film under the same conditions, the barrier property was deteriorated and the result was evaluation x.

It is sectional drawing which shows an example of a structure of a sealing film and an organic EL element. It is sectional drawing which shows another example of a structure of a sealing film and an organic EL element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 1st electrode 3 Organic EL layer 4 2nd electrode 5 1st inorganic barrier film 6 Inorganic stress relaxation film 7 2nd inorganic barrier film 8 Adhesive 9 Protective film member

Claims (4)

On the substrate, the first electrode, an organic electroluminescent layer composed of one or more organic compound films including a light emitting layer formed on the first electrode, the second electrode, and further on the second electrode,
In an organic electroluminescence device in which a sealing film having at least one unit composed of three layers of a first inorganic film, a second inorganic film, and a third inorganic film composed of at least silicon, nitrogen, and oxygen is formed.
When the nitrogen and oxygen components of the first and third inorganic films are observed in terms of atomic number concentration, the amount of the components increases in the order of nitrogen and oxygen, and when the nitrogen and oxygen components of the second inorganic film are viewed in atomic number concentration An organic electroluminescence device characterized in that the amount of components in the order of oxygen and nitrogen is large. The organic electroluminescence device according to claim 1, wherein the first inorganic film is thinner than the third inorganic film. The organic electroluminescence element according to claim 1, wherein the second inorganic film is thicker than the third inorganic film. The organic electroluminescence element according to claim 1, wherein the first inorganic film has a thickness of 20 to 70 nm.

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