JP2001060491A - Organic el element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element having a sealing film capable of being formed relatively easily without using any special structure for sealing, capable of being formed continuously with an electron injection electrode, and having high sealing effect. SOLUTION: This organic EL element has a substrate 21, a hole injection electrode 22 formed at least on the substrate 21, organic layers 23, 24 concerned in a luminescence function, and an electron injection electrode 25. A sealing film 26 is provided on the opposite side of the electron injection electrode 25 to the substrate 21, and the sealing film 26 contains silicon, oxygen, and nitrogen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an organic EL device using an organic compound, and more particularly, to an organic EL device having a sealing film provided on an electron injection electrode for supplying electrons to a light emitting layer.

[0002]

2. Description of the Related Art In an organic EL device, a hole transporting material such as triphenyldiamine (TPD) is deposited on a hole injection electrode to form a thin film, and a fluorescent material such as an aluminum quinolinol complex (Alq3) is laminated thereon as a light emitting layer. In addition, it is an element that has a basic structure in which a metal electrode (electron injection electrode) with a small work function, such as Mg, is formed, and can obtain extremely high luminance of several hundred to several 10,000 cd / m ² at a voltage of about 10 V. Have been.

Incidentally, it is known that the organic EL element is deteriorated by moisture, corrosive gas or the like. For example, due to the influence of moisture, separation occurs between the light-emitting layer and the electrode layer, or a constituent material is altered, a non-light-emitting region called a dark spot is generated, or a light-emitting area is reduced. As a result, light emission of a predetermined quality cannot be maintained.

It is considered that a material used as an electron injecting electrode of an organic EL device is effective in injecting a large amount of electrons into a light emitting layer, an electron injecting and transporting layer, and the like. In other words, it can be said that a material having a smaller work function is more suitable as an electron injection electrode. There are various materials having a small work function, and as a material used as an electron injection electrode of an organic EL element, for example, Japanese Patent Application Laid-Open No. 2-15595
The publication consists of a plurality of metals other than alkali metals,
And an electron injection electrode in which at least one of these metals has a work function of less than 4 eV, such as MgA
g is disclosed.

Further, alkali metals having a small work function are preferable, and US Pat. Nos. 3,173,050 and 3,382,394 describe, for example, NaK as an alkali metal. However, an electrode using an alkali metal has high activity and is chemically unstable, and is inferior to an electron injection electrode using MgAg or the like in terms of safety and reliability.

[0006] In order to stably use metals, alloys and the like having a low work function as described above, studies have been made on film sealing. However, in order to perform sufficient sealing, glass sealing or the like is insufficient, so that expensive and troublesome Teflon or SiO ₂ is required.
And the like. Further, when performing such film sealing, it is necessary to perform the film sealing immediately after the formation of the electron injection electrode in order to prevent the electron injection electrode from being corroded by oxidation. For this reason, there is a problem that it is impossible to cope with the problem unless an apparatus dedicated to film sealing is prepared.

As a method for solving this problem, for example, JP-A-5-36475 and JP-A-5-89959
As described in Japanese Patent Application Laid-Open Nos. 7-169567 and 7-169567, a technique for tightly fixing an airtight case, a sealing layer, and the like covering an organic EL layered structure portion on a substrate and shutting off the outside is known. ing.

As a study for preventing oxidation, for example, a method in which an Al cap layer is provided on Mg.Al as described in Japanese Patent Application Laid-Open No. Hei 4-233194, or a work more intense than an electron injection electrode material is described. Attempts have been made to provide a cap layer made of a low-function alkaline earth or rare earth metal. However, this cap layer is intended to prevent the appearance of dark spots, and mainly absorbs moisture at the interface between the cathode (electron injection electrode) and the organic electroluminescence medium, and the like. It is not sufficient as a sealing film for protecting the entire device.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to form a film relatively easily without using a special structure for sealing, and to form a film continuously from an electron injection electrode.
Moreover, it is an object of the present invention to provide an organic EL device having a sealing film having a high sealing effect.

[0010]

This and other objects are achieved by the present invention which is defined below as (1) to (5). (1) A substrate, at least a hole injection electrode formed on the substrate, an organic layer involved in a light emitting function, and an electron injection electrode, wherein the electron injection electrode has a sealing film on the side opposite to the substrate. An organic EL device comprising: a sealing film containing silicon, oxygen, and nitrogen. (2) The organic EL device according to (1) above, wherein the composition of the sealing film is x = 0.1 to 1, y = 0.1 to 1 when the composition is represented by SiO _x N _y . (3) The above (1) further containing 30 at% or less of hydrogen.
Or the organic EL device of (2). (4) The organic EL device according to any one of (1) to (3), wherein the sealing film is formed by a plasma CVD method. (5) The above (1) to (1) to further having a resin sealing structure.
The organic EL device according to any one of (4).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An organic EL device according to the present invention has a substrate, at least a hole injection electrode formed on the substrate, an organic layer involved in a light emitting function, and an electron injection electrode. The injection electrode has a sealing film on the side opposite to the substrate,
And this sealing film contains silicon, oxygen and nitrogen.

By forming a sealing film containing silicon, oxygen and nitrogen on the electron injection electrode, a high sealing effect can be obtained, and an increase in internal stress can be suppressed, and peeling or the like can be prevented. Defects are less likely to occur. Since a high sealing effect can be obtained without using a glass sealing plate, a sealing agent such as a resin can be used, and the range of application is widened.

[0013] That is, silicon nitride is excellent as a sealing film because it forms a dense film, but the stress in the film is large, and the sealing film itself and the electrode on which the sealing film is formed are in contact with the organic film. Separation phenomena tend to occur between layers and the like. In particular,
The peeling phenomenon progresses with the passage of time, and the shrinkage rate increases. Therefore, by introducing oxygen into the silicon nitride film, the internal stress is alleviated and peeling and shrinkage are suppressed while maintaining dense and excellent film properties.

[0014] The sealing film contains silicon, oxygen and nitrogen. The content of each element in the sealing film is not particularly limited, and may be any one formed by introducing a gas serving as an oxygen source during the formation of the silicon nitride film.

More specifically, Si is used as a silicon source as a silicon source, and silane, disilane or the like is used as a source gas. As a nitrogen source, N ₂ , NH ₃ or the like is used. Then, at the time of introducing the film forming raw material of the silicon nitride film, O ₂ or the like is further added as an oxygen source, and CO ₂ ,
NO, NO ₂ , N ₂ O, etc. are introduced using CO or the like as an oxygen-nitrogen source.

As a specific composition of the sealing film, when expressed as SiO _x N _y , x = 0.1 to 1, particularly 0.4 to 0.8,
y = 0.1 to 1, especially 0.4 to 0.8. The presence of these oxides can be confirmed by SIMS or the like.

The sealing film further contains hydrogen, preferably at 30 at.
%, More preferably 5 to 15 at%. By containing hydrogen, the stress in the sealing film is reduced. Hydrogen is inevitably mixed into the film when using the following CVD method.
Alternatively, a gas containing hydrogen can be mixed into the film.

The smaller the oxygen content in the sealing film, the better the stress in the film can be reduced.

As a film forming method, a plasma CVD method, a sputtering method or the like can be used.
Method D is preferred. By using the CVD method, the step coverage is further improved, and the sealing effect can be further improved.

When the plasma CVD method is used, the film forming conditions are as follows: pressure during film formation: 10 to 100 Pa, input power (RF: 13.56 MHz): 50 to 500 W, temperature during film formation: 80 to 150 About ℃.

The thickness of the formed sealing film is 100
nm to 1 μm, particularly preferably about 200 nm to 500 nm.
The internal stress in the sealing film is usually a tensile stress, preferably 5 × 10 ⁹ dyn / cm ² or less, particularly 5 × 10 ⁸ dyn / cm ^2.
The following is preferred. The lower limit is 0, which is the equilibrium point between the tensile and compressive stresses.

The electron injection electrode according to the present invention is made of a metal, alloy or intermetallic compound having a work function of 4 eV or less. If the work function of the material exceeds 4 eV, the electron injection efficiency decreases, and the luminous efficiency also decreases. Examples of the constituent metal of the electron injection electrode film having a work function of 4 eV or less include alkali metals such as Li, Na, and K, Mg, Ca, and S.
Examples thereof include alkaline earth metals such as r and Ba, rare earth metals such as La and Ce, Al, In, Ag, Sn, Zn, and Zr. As a constituent alloy of the electron injection electrode containing a metal having a work function of 4 eV or less, for example, Ag.Mg (Ag: 1
２０20 at%), Al.Li (Li: 0.5 to 12 at%)
%), In.Mg (Mg: 50-80 at%), Al.C
a (Ca: 5 to 20 at%). These may be present alone or as a combination of two or more, and the mixing ratio when two or more of these are combined is arbitrary.

This electron injection electrode can be formed by a vapor deposition method or the like, but is preferably formed by a sputtering method, more preferably a DC sputtering method. The power of the DC sputtering apparatus is preferably 0.1 to 10 W / cm ² ,
Particularly, a range of 0.5 to ⁷ W / cm ² is preferable. The film forming rate is preferably 0.1 to 100 nm / min, particularly 1 to 100 nm / min.
-30 nm / min is preferred.

The sputtering gas is not particularly limited, and an inert gas such as Ar, He, Ne, Kr, and Xe, or a mixed gas thereof may be used. As the pressure at the time of sputtering such a sputtering gas,
Usually, it may be about 0.1 to 20 Pa.

The thickness of such an electron injection electrode may be a certain thickness or more for sufficiently injecting electrons, and may be 1 nm or more, preferably 3 nm or more. The upper limit is not particularly limited, but the thickness may be generally about 3 to 500 nm.

In the organic EL device of the present invention, an auxiliary electrode layer may be provided on the electron injection electrode, that is, on the side opposite to the organic layer. This auxiliary electrode compensates for the case where the film resistance of the electron injection electrode is high, or when the film thickness is such that it has a minimum electron injection function, and when used as a simple matrix wiring electrode, Voltage drop is small, luminance unevenness can be prevented, and when applied to an active matrix type display using a TFT or the like, high-speed operation is possible.

The film resistance of the electron injection electrode requiring an auxiliary electrode is usually 0.2 Ω / □ or more, especially 0.5 Ω / □ or more, although it depends on the size of the display and the material of the auxiliary electrode. The upper limit is not particularly limited, but is usually several hundreds Ω / □. Although the thickness of such an electron injection electrode depends on the size of the display and the material of the auxiliary electrode, it is usually 300 nm or less, especially 2 nm.
It becomes necessary when the thickness becomes smaller than 00 nm.

When the auxiliary electrode functions as a wiring electrode, the specific resistance is preferably 500 μΩ · cm or less, more preferably 50 μΩ · cm, particularly 30 μΩ · cm or less, and further preferably 10 μΩ · cm or less. The lower limit is not particularly limited, but is 3 to 4 which is the specific resistance of Al.
About μΩ · cm. As the auxiliary electrode having such specific resistance, Al or an alloy of Al and a transition metal is preferably cited. In this case, the content of the transition metal in the Al. Transition metal alloy is preferably 5 at%, more preferably 2 at%, and particularly preferably 1 at% or less, and the use of Al alone is most preferable. The electron injecting electrode combined with the Al auxiliary electrode is not particularly limited, but is preferably an Al.Li alloy.

The thickness of the auxiliary electrode may be a certain thickness or more, preferably 50 nm or more, more preferably 100 nm or more, particularly 100 nm, in order to secure electron injection efficiency and prevent entry of moisture, oxygen or an organic solvent. A range of ~ 1000 nm is preferred. If the auxiliary electrode layer is too thin, the desired effect cannot be obtained, and the step coverage of the auxiliary electrode layer will be low, and the connection with the terminal electrode will not be sufficient. on the other hand,
If the auxiliary electrode layer is too thick, the stress of the auxiliary electrode layer increases, so that the growth rate of dark spots increases. The thickness when functioning as a wiring electrode is generally about 100 to 500 nm when the electron injection electrode is thin and the film resistance is high because the film thickness is small. Is about 100 to 300 nm.

The thickness of such a sealing film may be a certain thickness or more, preferably 5 nm or more, and more preferably 5 to 200 mm, in order to prevent entry of moisture, oxygen or an organic solvent.
nm, especially in the range of 10 to 100 nm.

The total thickness of the electron injection electrode and, if necessary, the auxiliary electrode is not particularly limited, but may be generally about 100 to 1000 nm.

The sputtering device is preferably a DC sputtering device. The sputtering gas is not particularly limited, and an inert gas such as Ar, He, Ne, Kr, and Xe, or a mixed gas thereof may be used. The flow rate of such a sputtering gas or reactive gas during sputtering is preferably 1 to 20 sccm, more preferably 1 to 1 sccm.
0 sccm, especially 2-5 sccm, is preferred. Other sputtering conditions are the same as in the case of the electron injection electrode described above.

The organic EL device manufactured by the present invention has at least one charge injection transport layer and at least one light emitting layer sandwiched between a hole injection electrode on a substrate and an electron injection electrode thereon. And a sealing film as the uppermost layer. Note that the charge injection transport layer can be omitted.

FIG. 1 shows an example of the structure of an organic EL device manufactured according to the present invention. The EL device shown in FIG. 1 has a hole injection electrode 22, a hole injection / transport layer 23, a light emission and electron injection / transport layer 24, an electron injection electrode 25, and a sealing film 26 in this order on a substrate 21. If necessary, an auxiliary electrode may be provided on the electron injection electrode 25, or an electron injection transport layer may be separately provided.

The organic EL device of the present invention is not limited to the illustrated example, but can be of various configurations. For example, a light emitting layer is provided alone, and an electron injection transport layer is provided between the light emitting layer and the electron injection electrode. An interposed structure may be used. If necessary, the hole injecting / transporting layer and the light emitting layer may be mixed.

The electron injection electrode and the sealing film can be formed as described above, the organic layer such as the light emitting layer can be formed by vacuum evaporation or the like, and the hole injection electrode can be formed by evaporation or sputtering. Each of the films can be patterned by a method such as etching after mask evaporation or film formation, if necessary, whereby a desired light emitting pattern can be obtained. Further, when the substrate is a thin film transistor (T
FT), wherein each film is formed according to the pattern,
The display and drive patterns can be used as they are.

It is preferable to determine the material and thickness of the hole injection electrode so that the transmittance of emitted light is 80% or more. Specifically, an oxide transparent conductive thin film is preferable. For example, tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), and zinc oxide ( ZnO) is preferable. These oxides may deviate somewhat from their stoichiometric composition. In ITO, In ₂ O ₃ and Sn
O ₂ is contained in a stoichiometric composition, but the oxygen content may be slightly deviated from this. The mixing ratio of SnO ₂ to In ₂ O ₃ is preferably 1 to 20 wt%, more preferably 5 to 12 wt%.
% Is preferred. The mixing ratio of ZnO to In ₂ O ₃ is 12
~ 32 wt% is preferred.

For forming a hole injection electrode, a sputtering method is preferable. As a sputtering method, a high frequency sputtering method using an RF power supply or the like is also possible, but a DC sputtering method is used in consideration of easy control of film physical properties of a hole injection electrode to be formed and smoothness of a film formation surface. Is preferred.

The power of the DC sputtering device is preferably in the range of 0.1 to 10 W / cm ² , particularly 0.5 to 7 W / cm ² . The deposition rate depends on the conditions of the apparatus such as a magnet, but is preferably in the range of 5 to 100 nm / min, particularly preferably in the range of 10 to 50 nm / min. The film forming conditions at the time of sputtering may be a gas pressure generally used for forming an electrode, for example, a range of 0.1 to 0.5 Pa and a distance between the substrate and the target of 4 to 10 cm.

The sputtering gas may be an inert gas used in a normal sputtering apparatus, or a reactive gas such as N ₂ , H ₂ , O ₂ , C ₂ H ₄ , NH _{3 in the case} of reactive sputtering. Although it can be used, it is preferable to use any of Ar, Kr, and Xe, or a mixed gas containing at least one or more of these gases. These gases are preferred because they are inert gases and have a relatively large atomic weight. Particularly, Ar, Kr, and Xe alone are preferred. Ar, K
By using the r and Xe gas, while the sputtered atoms reach the substrate, the collision with the gas is repeated,
The kinetic energy is reduced and reaches the substrate. From this, the kinetic energy of the sputtered atoms is
Physical damage to the L structure is reduced. Also,
A mixed gas containing at least one gas of Ar, Kr, and Xe may be used. When such a mixed gas is used, the total partial pressure of Ar, Kr, and Xe is set to 50% or more and used as a main sputtering gas. Used. Thus, Ar, Kr,
By using a mixed gas obtained by combining at least one kind of Xe and an arbitrary gas, reactive sputtering can be performed while maintaining the effects of the present invention.

Although a sufficient protection and sealing effect can be obtained by the sealing film of the present invention, a protective film may be formed on the sealing film if necessary. Protective film may be formed using an inorganic material such as SiO _x, an organic material such as Teflon or the like.
The protective film may be transparent or opaque, and the thickness of the protective film is about 50 to 1200 nm. The protective film may be formed by a general sputtering method, a vapor deposition method, or the like, in addition to the reactive sputtering method described above.

Further, it is preferable to provide a sealing layer on the element in order to prevent oxidation of the organic layer and the electrode of the element. The sealing layer is made of an adhesive resin layer such as a commercially available low-moisture-absorbing light-curing adhesive, an epoxy-based adhesive, a silicone-based adhesive, and a cross-linked ethylene-vinyl acetate copolymer adhesive sheet to prevent moisture from entering. Using acrylic, vinyl chloride, etc. resin plate,
A sealing plate such as a glass plate is bonded and sealed. In particular, in the organic EL device having the sealing film of the present invention, it is possible to use the above-mentioned resin plate as a resin sealing structure other than the glass plate, and further, vinyl chloride, PET (polyethylene terephthalate) , PP (polypropylene), polyimide and other resin films can also be used. By using such a thin film, the organic EL element can be bent and arranged, and a display device using the element can be further thinned, and the application range of the organic EL element is widened.

Next, the organic layer provided in the EL device of the present invention will be described. The organic layer includes a light emitting layer. The light emitting layer is at least one kind involved in the light emitting function,
Alternatively, it is composed of a laminated film of two or more kinds of organic compound thin films.

The light emitting layer has a function of injecting holes (holes) and electrons, a function of transporting them, and a function of generating excitons by recombination of holes and electrons. By using a relatively electronically neutral compound for the light emitting layer, electrons and holes can be easily injected and transported in a well-balanced manner.

The light emitting layer may have a hole injecting and transporting layer, an electron injecting and transporting layer, etc. in addition to the light emitting layer in a narrow sense, if necessary.

The hole injecting and transporting layer has a function of facilitating the injection of holes from the hole injecting electrode, a function of stably transporting holes, and a function of preventing electrons.
The electron injection transport layer has a function of facilitating injection of electrons from the electron injection electrode, a function of stably transporting electrons, and a function of preventing holes. These layers increase and confine holes and electrons injected into the light emitting layer, optimize the recombination region, and improve luminous efficiency.

The thickness of the light emitting layer, the thickness of the hole injecting and transporting layer, and the thickness of the electron injecting and transporting layer are not particularly limited, and vary depending on the forming method.
It is preferable that the thickness be in the range of 10 to 300 nm.

The thickness of the hole injecting and transporting layer and the thickness of the electron injecting and transporting layer depend on the design of the recombination / light emitting region, but may be about the same as the thickness of the light emitting layer or about 1/10 to 10 times. When the hole / electron injection layer and the transport layer are separated, the thickness of the injection layer is preferably 1 nm or more, and the thickness of the transport layer is preferably 1 nm or more. At this time, the upper limit of the thickness of the injection layer and the transport layer is usually about 500 nm for the injection layer and about 500 nm for the transport layer. Such a film thickness is the same when two injection / transport layers are provided.

The light emitting layer of the organic EL device contains a fluorescent substance which is a compound having a light emitting function. Examples of such a fluorescent substance include, for example, JP-A-63-26469.
No. 2 discloses at least one compound selected from compounds such as quinacridone, rubrene, and styryl dyes. Also, Tris (8
Quinolinol derivatives such as metal complex dyes having 8-quinolinol or a derivative thereof as a ligand, such as (quinolinolato) aluminum; tetraphenylbutadiene, anthracene, perylene, coronene, and 12-phthaloperinone derivatives. Further, phenylanthracene derivatives described in JP-A-8-12600 (Japanese Patent Application No. 6-110569), tetraarylethene derivatives described in JP-A-8-12969 (Japanese Patent Application No. 6-114456), and the like are described. Can be used.

Further, it is preferable to use in combination with a host substance capable of emitting light by itself, and it is also preferable to use it as a dopant. In such a case, the content of the compound in the light emitting layer is 0.01 to 10% by weight, and more preferably 0.1 to 10% by weight.
It is preferably 1 to 5% by weight. When used in combination with a host substance, the emission wavelength characteristics of the host substance can be changed, light emission shifted to a longer wavelength becomes possible, and the luminous efficiency and stability of the device are improved.

As the host substance, a quinolinolato complex is preferable, and an aluminum complex having 8-quinolinol or a derivative thereof as a ligand is preferable. Such an aluminum complex is disclosed in JP-A-63-26469.
No. 2, JP-A-3-255190, JP-A-5-7073
3, JP-A-5-258859, JP-A-6-2158
No. 74 and the like.

Specifically, first, tris (8-quinolinolato) aluminum, bis (8-quinolinolato) magnesium, bis (benzo {f} -8-quinolinolato) zinc, bis (2-methyl-8-quinolinolato) aluminum Oxide, tris (8-quinolinolato) indium,
Tris (5-methyl-8-quinolinolato) aluminum, 8-quinolinolatolithium, tris (5-chloro-
8-quinolinolato) gallium, bis (5-chloro-8-
Quinolinolato) calcium, 5,7-dichloro-8-quinolinolatoaluminum, tris (5,7-dibromo-
8-hydroxyquinolinolato) aluminum and poly [zinc (II) -bis (8-hydroxy-5-quinolinyl) methane].

In addition to 8-quinolinol or a derivative thereof, an aluminum complex having another ligand may be used, such as bis (2-methyl-
8-quinolinolato) (phenolato) aluminum (III)
, Bis (2-methyl-8-quinolinolato) (ortho-
Cresolato) aluminum (III), bis (2-methyl-
8-quinolinolato) (meth-cresolate) aluminum
(III), bis (2-methyl-8-quinolinolato) (para-cresolato) aluminum (III), bis (2-methyl-8-quinolinolato) (ortho-phenylphenolate)
Aluminum (III), bis (2-methyl-8-quinolinolato) (meth-phenylphenolato) aluminum (II
I), bis (2-methyl-8-quinolinolato) (para-
Phenylphenolato) aluminum (III), bis (2-
Methyl-8-quinolinolato) (2,3-dimethylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (2,6-dimethylphenolato) aluminum (III), bis (2-methyl- 8-quinolinolato)
(3,4-dimethylphenolato) aluminum (III),
Bis (2-methyl-8-quinolinolato) (3,5-dimethylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (3,5-di-tert-butylphenolato) aluminum (III) ), Bis (2-methyl-8)
-Quinolinolato) (2,6-diphenylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (2,4,6-triphenylphenolato) aluminum (III), bis (2-methyl- 8-quinolinolato)
(2,3,6-trimethylphenolato) aluminum (I
II), bis (2-methyl-8-quinolinolato) (2,
3,5,6-tetramethylphenolato) aluminum (I
II), bis (2-methyl-8-quinolinolato) (1-naphthrat) aluminum (III), bis (2-methyl-8
-Quinolinolato) (2-naphthrat) aluminum (II
I), bis (2,4-dimethyl-8-quinolinolato)
(Ortho-phenylphenolato) aluminum (III),
Bis (2,4-dimethyl-8-quinolinolato) (para-
Phenylphenolato) aluminum (III), bis (2,
4-dimethyl-8-quinolinolato) (meta-phenylphenolato) aluminum (III), bis (2,4-dimethyl-8-quinolinolato) (3,5-dimethylphenolato) aluminum (III), bis (2 4-dimethyl-8
-Quinolinolato) (3,5-di-tert-butylphenolato) aluminum (III), bis (2-methyl-4-ethyl-8-quinolinolato) (para-cresolato) aluminum (III), bis (2-methyl) -4-methoxy-8-quinolinolato) (para-phenylphenolato) aluminum (III), bis (2-methyl-5-cyano-8-quinolinolato) (ortho-cresolato) aluminum (III),
Bis (2-methyl-6-trifluoromethyl-8-quinolinolato) (2-naphthrat) aluminum (III);

In addition, bis (2-methyl-8-quinolinolato) aluminum (III) -μ-oxo-bis (2-
Methyl-8-quinolinolato) aluminum (III), bis (2,4-dimethyl-8-quinolinolato) aluminum
(III) -μ-oxo-bis (2,4-dimethyl-8-quinolinolato) aluminum (III), bis (4-ethyl-
2-methyl-8-quinolinolato) aluminum (III)-
μ-oxo-bis (4-ethyl-2-methyl-8-quinolinolato) aluminum (III), bis (2-methyl-4
-Methoxyquinolinolato) aluminum (III) -μ-oxo-bis (2-methyl-4-methoxyquinolinolato)
Aluminum (III), bis (5-cyano-2-methyl-
8-quinolinolato) aluminum (III) -μ-oxo-
Bis (5-cyano-2-methyl-8-quinolinolato) aluminum (III), bis (2-methyl-5-trifluoromethyl-8-quinolinolato) aluminum (III) -μ
-Oxo-bis (2-methyl-5-trifluoromethyl-8-quinolinolato) aluminum (III) and the like.

Other host materials are disclosed in
Phenylanthracene derivative described in JP-A-12600 (Japanese Patent Application No. 6-110569) and JP-A-8-1296
No. 9 (Japanese Patent Application No. 6-114456) is also preferable.

The light emitting layer may also serve as an electron transporting layer. In such a case, tris (8-quinolinolato)
It is preferable to use aluminum or the like. These fluorescent substances may be deposited.

The light emitting layer is preferably a mixed layer of at least one kind of hole injecting and transporting compound and at least one kind of electron injecting and transporting compound, if necessary.
Further, it is preferable that a dopant is contained in the mixed layer. The content of the compound in such a mixed layer is preferably 0.01 to 20% by weight, more preferably 0.1 to 15% by weight.

In the mixed layer, a carrier hopping conduction path is formed, so that each carrier moves in a substance having a polar advantage, and carrier injection of the opposite polarity is less likely to occur, so that the organic compound is less likely to be damaged. This has the advantage that the element life is extended. Further, by including the above-described dopant in such a mixed layer, the emission wavelength characteristics of the mixed layer itself can be changed, the emission wavelength can be shifted to a longer wavelength, and the emission intensity is increased, The stability of the device can be improved.

The hole injecting and transporting compound and the electron injecting and transporting compound used in the mixed layer may be selected from the hole injecting and transporting compound and the electron injecting and transporting compound described below, respectively.

As the compound capable of injecting and transporting electrons, it is preferable to use a quinoline derivative, furthermore a metal complex having 8-quinolinol or a derivative thereof as a ligand, particularly tris (8-quinolinolato) aluminum (Alq 3). It is also preferable to use the above-mentioned phenylanthracene derivatives and tetraarylethene derivatives.

As the compound for the hole injecting and transporting layer, it is preferable to use an amine derivative having strong fluorescence, for example, a triphenyldiamine derivative, a styrylamine derivative, or an amine derivative having an aromatic condensed ring.

The mixing ratio in this case depends on the respective carrier mobility and carrier concentration. In general, the weight ratio of the hole injection / transport compound / electron injection / transport compound is 1
/ 99-99 / 1, more preferably 10 / 90-90
/ 10, particularly preferably about 20/80 to 80/20.

The thickness of the mixed layer is preferably not less than the thickness corresponding to one molecular layer and less than the thickness of the organic compound layer. Specifically, the thickness is preferably 1 to 100 nm, more preferably 5 to 60 nm, particularly preferably 5 to 50 nm.

As a method for forming a mixed layer, co-evaporation in which evaporation is performed from different evaporation sources is preferable. However, when the vapor pressures (evaporation temperatures) are approximately the same or very close, they are mixed in advance in the same evaporation board. Alternatively, it can be deposited. In the mixed layer, it is preferable that the compounds are uniformly mixed, but in some cases, the compounds may exist in an island shape. The light-emitting layer is generally formed to a predetermined thickness by vapor-depositing an organic fluorescent substance or by dispersing and coating the resin in a resin binder.

Examples of the hole injecting / transporting compound include, for example, JP-A-63-29569 and JP-A-2-19.
1694, JP-A-3-792, JP-A5-
JP-A-234681, JP-A-5-239455,
JP-A-5-299174, JP-A-7-12622
No. 5, JP-A-7-126226, JP-A-8-
Various organic compounds described in, for example, Japanese Patent No. 100172 and EP0650955A1 can be used. For example, a tetraarylbendicine compound (triaryldiamine or triphenyldiamine: TPD), an aromatic tertiary amine, a hydrazone derivative, a carbazole derivative,
Triazole derivatives, imidazole derivatives, oxadiazole derivatives having an amino group, polythiophene and the like. These compounds may be used alone or in combination of two or more. When two or more kinds are used in combination, they may be stacked as separate layers or mixed.

The electron injecting and transporting compound includes quinoline derivatives such as organometallic complexes having 8-quinolinol such as tris (8-quinolinolato) aluminum (Alq3) or derivatives thereof as ligands, oxadiazole derivatives, perylene derivatives, and the like. A pyridine derivative, a pyrimidine derivative, a quinoxaline derivative, a diphenylquinone derivative, a nitro-substituted fluorene derivative, or the like can be used.

The light emitting layer, the hole injection / transport layer, and the electron injection / transport layer can be formed from a uniform thin film.
It is preferable to use a vacuum deposition method. When vacuum deposition is used, the amorphous state or the crystal grain size is 0.2 μm
In particular, a homogeneous thin film of 0.1 μm or less can be obtained. If the crystal grain size exceeds 0.2 μm, especially 0.1 μm, the light emission becomes non-uniform, the driving voltage of the device must be increased, and the charge injection efficiency is significantly reduced.

The conditions for vacuum deposition are not particularly limited.
The degree of vacuum is 0 ^-4 Pa or less, and the deposition rate is 0.01 to 1 nm /
It is preferable to set it to about sec. Further, it is preferable to form each layer continuously in a vacuum. If they are formed continuously in a vacuum, impurities can be prevented from adsorbing at the interface between the layers, so that high characteristics can be obtained. Further, the driving voltage of the element can be reduced, and the occurrence and growth of dark spots can be suppressed.

When a plurality of compounds are contained in one layer when a vacuum evaporation method is used to form each of these layers, it is preferable to co-deposit each boat containing the compounds by individually controlling the temperature.

In the case of a structure in which light emitted from the substrate side is extracted, a transparent or translucent material such as glass, quartz, or resin is used as the substrate material. Further, the emission color may be controlled by using a color filter film, a color conversion film containing a fluorescent substance, or a dielectric reflection film on the substrate. In the case of the reverse lamination, the substrate may be transparent or opaque, and when opaque, ceramics or the like may be used. As the color filter film, a color filter used in a liquid crystal display or the like may be used, but the characteristics of the color filter may be adjusted according to the light emitted by the organic EL, and the extraction efficiency and color purity may be optimized. .

When a color filter capable of cutting off short-wavelength external light that is absorbed by the EL element material or the fluorescence conversion layer is used, the light resistance of the element and the contrast of display are improved.

Further, an optical thin film such as a dielectric multilayer film may be used instead of the color filter.

The fluorescence conversion filter film absorbs EL light and emits light from the phosphor in the fluorescence conversion film, thereby performing color conversion of the emission color. It is formed from a fluorescent material and a light absorbing material.

As the fluorescent material, basically, a material having a high fluorescence quantum yield may be used, and it is desirable that the fluorescent material has strong absorption in the EL emission wavelength region. Actually, laser dyes are suitable, and rhodamine compounds, perylene compounds, cyanine compounds, phthalocyanine compounds (including subphthalo, etc.) naphthaloimide compounds, condensed ring hydrocarbon compounds, condensed heterocyclic compounds, A styryl compound, a coumarin compound, or the like may be used.

Basically, a material that does not extinguish the fluorescence may be selected as the binder, and a material that can be finely patterned by photolithography, printing, or the like is preferable.
Further, a material that does not suffer damage during the deposition of ITO is preferable. The light absorbing material is used when the light absorption of the fluorescent material is insufficient, but may not be used when unnecessary. As the light absorbing material, a material that does not quench the fluorescence of the fluorescent material may be selected.

The organic EL device of the present invention is usually used as a DC drive type EL device, but it can be AC drive or pulse drive. The applied voltage is usually 2 to 2
It is about 0V.

[0077]

EXAMPLES Hereinafter, the present invention will be described in more detail by showing specific examples of the present invention together with comparative examples.

Example 1 As a glass substrate, a 7059 substrate (trade name, manufactured by Corning Incorporated) was scrub-cleaned using a neutral detergent.

The substrate was fixed on a substrate holder of a sputtering apparatus, and the pressure in the tank was reduced. Next, an ITO hole injection electrode having a thickness of 100 nm was formed by a DC magnetron sputtering method using an ITO target.

The ITO substrate patterned as desired is
Ultrasonic cleaning was performed using a neutral detergent, acetone, and ethanol, and the resultant was pulled out of boiling ethanol and dried. Next, after the surface was washed with UV / O _3, it was fixed to a substrate holder of a vacuum evaporation apparatus, and the pressure in the tank was reduced to 1 × 10 ⁻⁴ Pa or less.

Next, 4,4 ′, 4 ″-
Tris (-N- (3-methylphenyl) -N-phenylamino) triphenylamine (m-MTDATA) was deposited at a deposition rate of 0.1 nm / sec to a thickness of 55 nm to form a hole injection layer. , N'-diphenyl-N, N'-m
-Tolyl-4,4'-diamino-1,1'-biphenyl (TPD) was deposited at a deposition rate of 0.1 nm / sec to a thickness of 20 nm to form a hole transport layer.

While maintaining the reduced pressure, tris (8-quinolinolato) aluminum (Alq3) was deposited at a deposition rate of 0.1 nm.
The film was vapor-deposited at a thickness of 50 nm as / sec to form a light emitting layer.

Further, while maintaining the reduced pressure, the wafer was transferred to a sputtering apparatus, and AlLi (Li: 6 at%) was reduced to 1 by a sputtering method.
A film was formed to a thickness of 200 nm, and subsequently Al was formed to a thickness of 200 nm to form an electron injection electrode.

Next, while maintaining the reduced pressure, the wafer was transferred to a plasma CVD apparatus, and a SiON sealing film was formed to a thickness of 100 nm. The film forming conditions at this time were SiH ₄ : 20 SCCM N ₂ O: 10 SCCM N ₂ : 100 SCCM Film forming temperature: 100 ° C. Film forming pressure: 50 Pa Input power: RF100 W The composition of the formed sealing film is SiO _0.5 N _0.5
Met. Further, 10 at% of hydrogen was mixed in this sealing film.

Finally, an organic EL device was obtained without disposing a glass sealing plate. As a comparative example, an element (comparative sample) in which a sealing film was formed in the same manner as described above except that NH ₄ was introduced instead of N ₂ O when forming the sealing film was also manufactured.

The obtained organic EL device was stored in the atmosphere at 85 ° C. for 100 hours, and then driven at a constant current density of 10 mA / cm ² to evaluate generation of dark spots and shrinkage.

As a result, in the sample of the present invention, neither generation of a dark spot nor shrinkage was found, but in the comparative sample, many dark spots having a diameter of 50 μm or more were found, and shrinkage of 60 μm or more was found. confirmed.

[0088]

As described above, according to the present invention, a film can be formed relatively easily without using a special structure for sealing.
An organic EL element which can be formed continuously from an electron injection electrode and has a sealing film having a high sealing effect can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a basic configuration of an organic EL device of the present invention.

[Explanation of symbols]

 21 Substrate 22 Hole Injection Electrode 23 Hole Injection / Transport Layer 24 Electron Injection / Emission Layer 25 Electron Injection Electrode 26 Sealing Film

Claims (5)

[Claims] 1. A substrate, at least a hole injection electrode formed on the substrate, and an organic layer involved in a light emitting function.
An organic EL device comprising: an electron injection electrode; wherein the electron injection electrode has a sealing film on a side opposite to the substrate, and the sealing film contains silicon, oxygen, and nitrogen. 2. The sealing film has a composition of SiO _x N _y.
The organic EL device according to claim 1, wherein x = 0.1 to 1, and y = 0.1 to 1. 3. The organic EL device according to claim 1, further comprising 30 at% or less of hydrogen. 4. The organic EL device according to claim 1, wherein said sealing film is formed by a plasma CVD method. 5. The method according to claim 1, further comprising a resin sealing structure.
4. The organic EL device according to any one of items 1 to 4,