JP2012169266A - Organic el element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element which improves luminous efficiency and lowers a driving voltage.SOLUTION: An organic EL element 1 comprises: an anode 3; a first organic layer 4; an intermediate electrode 5; a second organic layer 6; and a cathode 7 on a substrate 2. The intermediate electrode 5 includes at least one layer of a metal film 52, and the metal film 52 is a discontinuous film including a metal having particles growing into pillar shapes. Further, a layer, which contacts with the anode 3 side of the metal film 52, is a layer 51 containing an alkali metal or an alkali earth metal or a layer including a compound containing alkali metal ions or alkali earth metal ions.

Description

  The present invention relates to an organic EL (electroluminescence) element.

  The organic EL element can emit light at a low voltage of, for example, several V to several tens V, and can emit various colors by selecting the type of the fluorescent organic compound. Applications to light-emitting elements, display elements, and the like are expected. For this reason, various proposals have been made for application to various elements.

  For example, Patent Document 1 proposes an organic EL display device in which an intermediate conductive layer is newly formed in an element separately from an anode and a cathode. According to Patent Document 1, it can be manufactured with a higher degree of freedom, and a wide emission wavelength region can be obtained. Moreover, the manufacturing process is simple and a high-brightness organic EL display device can be obtained.

  In Patent Document 2, in order to widen the selection range of materials used for the intermediate conductive layer of Patent Document 1, at least one of the layer responsible for electron injection and the layer responsible for hole injection of the intermediate conductive layer is defined as an island-shaped layer. A light emitting device has been proposed. According to Patent Document 2, it is possible to obtain a light-emitting element with a wide light-emitting efficiency and low power consumption while widening the selection range of materials used for the intermediate conductive layer.

Japanese Patent Laid-Open No. 11-329748 JP 2006-5340 A

  By the way, in order for a metal film used as an intermediate conductive layer or the like to function as an electrode, a film thickness of 1 nm or more, preferably 4 nm or more is required. When the film thickness is 4 nm or less, the driving voltage of the element increases. There is a problem of end. However, if the metal electrode film, which is an island-shaped layer of Patent Document 2, has a film thickness of 4 nm or more, the islands are combined to form a continuous film, and the light transmittance is greatly reduced. In addition, off-dot light emission occurs due to a decrease in insulation in the film surface direction of the metal electrode film. For this reason, there is a problem that the luminous efficiency of the element is lowered, and further, matrix display as a display cannot be performed.

  This invention is made | formed in view of the said situation, and it aims at providing the organic EL element which can make a drive voltage low while making luminous efficiency high.

In order to achieve the above object, the organic EL device according to the first aspect of the present invention is:
Laminating at least an anode, a first organic layer having a light emitting function, an intermediate electrode, a second organic layer having a light emitting function, and a cathode on a substrate;
The intermediate electrode includes at least one metal film,
The metal film is a discontinuous film containing a metal in which particles grow in a columnar shape.

The organic EL device according to the second aspect of the present invention is:
Laminating at least an anode, a first organic layer having a light emitting function, an intermediate electrode, a second organic layer having a light emitting function, and a cathode on a substrate;
The intermediate electrode includes at least one metal film,
The metal film is a film containing an amorphous metal composed of two or more metal elements, and at least one metal element is present without forming a solid solution with other metal elements. .

The organic EL device according to the third aspect of the present invention is:
Laminating at least an anode, a first organic layer having a light emitting function, an intermediate electrode, a second organic layer having a light emitting function, and a cathode on a substrate;
The intermediate electrode includes at least one metal film,
The metal film contains at least aluminum and indium.

  The distance from the cathode to the intermediate electrode is preferably λ / 2n (λ is the emission wavelength, and n is the refractive index between the cathode and the intermediate electrode).

The organic EL device according to the fourth aspect of the present invention is:
At least an anode, an organic layer having a light emitting function, and a cathode are sequentially laminated on the substrate,
The cathode includes at least one metal layer;
The metal film is a discontinuous film containing a metal in which particles grow in a columnar shape.

The organic EL device according to the fifth aspect of the present invention is:
At least an anode, an organic layer having a light emitting function, and a cathode are sequentially laminated on the substrate,
The cathode includes at least one metal layer;
The metal film is a film containing an amorphous metal composed of two or more metal elements, and at least one metal element is present without forming a solid solution with other metal elements. .

The organic EL device according to the sixth aspect of the present invention is:
At least an anode, an organic layer having a light emitting function, and a cathode are sequentially laminated on the substrate,
The cathode includes at least one metal layer;
The metal film contains at least aluminum and indium.

The mixing ratio of aluminum and indium is preferably 88:12 to 35:65 by weight ratio.
The mixing ratio of aluminum and indium is preferably 88:12 to 53:47 by weight ratio.

The layer in contact with the anode side of the metal film includes, for example, an alkali metal or an alkaline earth metal.
The layer in contact with the anode side of the metal film contains, for example, a compound containing alkali metal ions or alkaline earth metal ions.

  ADVANTAGE OF THE INVENTION According to this invention, while improving luminous efficiency, the organic EL element which can make a drive voltage low can be provided.

It is a figure which shows the structural example of the organic EL element of the 1st and 2nd embodiment of this invention. It is a figure for demonstrating the structure of the metal film of 1st Embodiment. It is a figure for demonstrating the structure of the columnar growth film of this invention. It is a figure for demonstrating the structure of the conventional island-like growth film. It is a figure which shows the other structural example of an organic EL element. It is a figure for demonstrating the structure of the metal film of 2nd Embodiment. It is a figure which shows the structural example of the organic EL element of 3rd Embodiment. It is a figure which shows the structural example of the organic EL element of 4th Embodiment. FIG. 3 is a view showing a structure of a metal film of Example 1. 6 is a view showing a structure of a metal film of Comparative Example 1. FIG. It is a figure which shows the structure of the metal film of Example 71. It is a figure which shows the relationship between In addition amount and the transmittance | permeability.

  Hereinafter, the organic EL element of the present invention will be described.

(First embodiment)
In this embodiment, the organic EL element of the present invention is applied to an organic EL element having a tandem structure in which a plurality of organic layers having a light emitting function are stacked and an intermediate electrode is formed between the organic layers. explain. FIG. 1 is a diagram illustrating an example of the configuration of the organic EL element according to the first embodiment.

  As shown in FIG. 1, the organic EL element 1 includes an anode 3, a first organic layer 4, an intermediate electrode 5, a second organic layer 6, and a cathode 7 on a substrate 2. .

  The board | substrate 2 is formed from the transparent material, for example, is formed from the glass plate, the transparent plastic sheet, transparent ceramics, etc. Further, the emission color may be controlled by combining the substrate 2 with, for example, a color filter film, a color conversion film, a dielectric reflection film, or the like.

  The anode 3 is connected to an external power source (not shown) and has a function of providing holes to the organic layer. The anode 3 is formed of a transparent material, and it is preferable to use a metal, an alloy, or an electrically conductive compound having a relatively large work function as an electrode material. Examples of the electrode material used for the anode 3 include gold, platinum, silver, copper, cobalt, nickel, palladium, vanadium, tungsten, tin oxide, zinc oxide, ITO (indium tin oxide), polythiophene, and polypyrrole. Can be mentioned. These electrode materials may be used alone or in combination. The anode 3 can form these electrode materials on the substrate 2 by, for example, a vapor phase growth method such as a vapor deposition method or a sputtering method. The anode 3 may have a single layer structure or a multilayer structure.

  The first organic layer 4 is made of an organic material having a light emitting function. In the present embodiment, the first organic layer 4 includes a hole injection / transport layer 41, a light emitting layer 42, and an electron injection / transport layer 43.

  The hole injection / transport layer 41 is a layer containing a compound having a function of facilitating injection of holes from the anode 3, a function of transporting the injected holes, and a function of blocking electrons. Materials used for the hole injection transport layer 41 include aromatic amine compounds such as tetraphenyldiaminobiphenyl derivatives (TPD) and triarylamine derivatives, phthalocyanine derivatives, triarylmethane derivatives, oxazole derivatives, hydrazone derivatives, stilbene derivatives, Examples thereof include those using at least one of pyrazoline derivatives, polysilane derivatives, polyphenylene vinylene and derivatives thereof, polythiophene and derivatives thereof, and poly-N-vinylcarbazole derivatives. A compound having a hole injecting and transporting function may be used alone or in combination.

  Among the aromatic amine compounds, a stable thin film is obtained because of low crystallinity and a high glass transition temperature, and among the aromatic amine compounds, the following formula ( The tetraaryldiamine derivative represented by I) is preferable.

Describing the formula (I), R _{1 to} R ₄ each independently represents an aryl group, a fluorene group, a carbazolyl group, an alkyl group, an alkoxy group, an aryloxy group, an amino group or a halogen atom, and R _{1 to} R ₄ At least one of them is an aryl group. r1 to r4 are each 0 or an integer of 1 to 5, and r1 to r4 are not 0 at the same time. Therefore, the sum of r1 to r4 is 1 or more. R ₅ and R ₆ each independently represents an aryl group, an alkyl group, an alkoxy group, an aryloxy group, an amino group or a halogen atom. r5 and r6 are each 0 or an integer of 1-4.

The aryl group represented by R _{1 to} R ₄ may be monocyclic or polycyclic, and includes condensed rings. The total number of carbon atoms is preferably 6 to 20, and may have a substituent. Examples of the substituent in this case include an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an amino group, and a halogen atom.
Specific examples of the aryl group represented by R _{1 to} R ₄ include a phenyl group, (o-, m-, p-) tolyl group, pyrenyl group, naphthyl group, anthryl group, biphenyl group, phenylanthryl group, Examples include a tolyl anthryl group, and a phenyl group is preferable because it has a particularly high hole transport property and a large energy gap between HOMO and LUMO.

The alkyl group represented by R _{1 to} R ₄ may be linear or branched. The alkyl group is preferably one having 1 to 10 carbon atoms, and may have a substituent, from the reason that hole transportability and vapor deposition film formation are easy. Examples of the substituent in this case are the same as those of the aryl group.
Specific examples of the alkyl group represented by R _{1 to} R ₄ include a methyl group, an ethyl group, a (n-, i-) propyl group, a (n-, i-, s-, t-) butyl group, and the like. Can be mentioned.

As the alkoxy group represented by R _{1 to} R ₄ , an alkyl group having 1 to 6 carbon atoms is preferable, and specific examples thereof include a methoxy group, an ethoxy group, and a t-butoxy group. The alkoxy group may be further substituted. Examples of the substituent in this case are the same as those of the aryl group.
Examples of the aryloxy group represented by R _{1 to} R ₄ include a phenoxy group, a 4-methylphenoxy group, and a 4- (t-butyl) phenoxy group.
The amino group represented by R _{1 to} R ₄ may be unsubstituted or may have a substituent, but preferably has a substituent. Specific examples thereof include a dimethylamino group, a diethylamino group, and diphenyl. Examples include an amino group, a phenyl-tolylamino group, and a bis (biphenyl) amino group.
Examples of the halogen atom represented by R _{1 to} R ₄ include a chlorine atom and a bromine atom.

At least one of R _{1 to} R ₄ is an aryl group, more preferably 2 or more, and particularly preferably 3 or more. Therefore, it is preferable that 2 or more, more preferably 3 or more of r1 to r4 are integers of 1 or more, and 2 or more of r1 to r4, more preferably 3 or more, is 1.

Examples of the aryl group, alkyl group, alkoxy group, aryloxy group, amino group, and halogen atom represented by R ₅ and R ₆ are the same as those described in the description of R _{1 to} R ₄ .
Both r5 and r6 are preferably 0.
Incidentally, when r1~r4 is an integer of 2 or more, each _R 1 to R ₄ each other may be different in each identical. When r5 and r6 are integers of 2 or more, R ₅ and R ₆ may be the same or different.

Among the compounds represented by the formula (I), a compound represented by the formula (I-1) or the formula (I-2) is preferable.

In formulas (I-1) and (I-2), R _{7 to} R ₁₀ each independently represents an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an amino group, or a halogen atom. Specific examples thereof are the same as those described in the description of R _{1 to} R _{4 in} the formula (I).
r7 to r10 are each 0 or an integer of 1 to 4, and are preferably 0 in both formula (I-1) and formula (I-2).
R _{11 to} R ₁₄ each independently represents an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an amino group, or a halogen atom, and these may be the same or different. Specific examples thereof are the same as those described in the description of R _{1 to} R _{4 in} the formula (I).
r11 to r14 are each an integer of 0 or 1 to 5.
In formula (I-1) and formula (I-2), R ₅ , R ₆ , r5 and r6 have the same meaning as in formula (I), and it is preferable that r5 = r6 = 0.

In the expression (I-1) and Formula (I-2), when r7~r10 is an integer of 2 or more, respectively, each of _R 7 _{to R 10} each other may be different even in the same, also r11 ~r14 when is an integer of 2 or more, respectively, each of _R 11 _{to R 14} each other may be different in the same.

Of the compounds represented by formula (I), the compound represented by formula (I-3) is also preferred.

In the formula (I-3), R ₅ , R ₆ , r5 and r6 have the same meaning as in the formula (I), and it is preferable that r5 = r6 = 0.
Ar ₁ and Ar ₂ each independently represent an aryl group, and these may be the same or different. Specific examples of the aryl group include the same as those described for R _{1 to} R _{4 in} formula (I), and a phenyl group or a biphenyl group is particularly preferable.
R ₁₅ and R ₁₆ each independently represents an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an amino group or a halogen atom. Specific examples thereof are the same as those described in the description of R _{1 to} R _{4 in} the formula (I).
r15 and r16 are 0 or an integer of 1 to 4, but it is preferable that r15 = r16 = 0.
R ₁₇ and R ₁₈ each independently represents an alkyl group, an alkoxy group, an aryloxy group, an amino group or a halogen atom. Specific examples thereof are the same as those described in the description of R _{1 to} R _{4 in} the formula (I).
r17 and r18 are 0 or an integer of 1 to 5, and it is preferable that r17 = r18 = 0.

In the expression (I-3), r15, r16 when is an integer of 2 or _{more, R 15} to each _other, may be different even among _{R 16} are each identical, r17, r18 is 2 or more integer In some cases, R ₁₇ and R ₁₈ may be the same or different.

  The hole injecting and transporting layer 41 is provided as necessary in consideration of the height of each function of hole injecting and hole transporting of the compound used for the light emitting layer 42. For example, when the compound used for the light emitting layer 42 has a high hole injecting and transporting function, the light emitting layer 42 can also serve as the hole injecting and transporting layer 41 without providing the hole injecting and transporting layer 41. The hole injection / transport layer 41 may be provided separately for the layer having an injection function and the layer having a transport function.

  The light emitting layer 42 is a layer containing a compound having a function of injecting holes and electrons, a function of transporting them, and a function of generating excitons by recombination of holes and electrons (light emitting function). As a material used for the light emitting layer 42, an organic material having a quinolinol ring such as a coumarin derivative, quinacridone, rubrene, a styryl dye, tris (8-quinolinolato) aluminum, or an organic metal coordinated by an organic material having a quinolinol ring is used. Quinoline derivatives such as complexes, tetraphenylbutadiene, anthracene derivatives, naphthacene derivatives, perylene, coronene, 12-phthaloperinone derivatives, phenylanthracene derivatives, tetraarylethene derivatives, fluoranthene derivatives, acenaphthofluoranthene derivatives, tetraphenyldiaminobiphenyl derivatives ( And aromatic amine compounds such as TPD) and triarylamine derivatives. In particular, it contains at least one compound among the compounds represented by the above formula (I) and the following formulas (II), (IIIa), (IV), (V), (VI), (VII). It is preferable because desired light emission from blue to red can be obtained with high efficiency, continuous driving life and heat resistance can be ensured, and driving can be performed at a low voltage. Hereinafter, the compounds represented by the formulas (II), (IIIa), (IV), (V), (VI), and (VII) will be described.

In formula (II), A ₁₀₁ represents a monophenylanthryl group which may have a substituent or a diphenylanthryl group which may have a substituent. n is 1 or 2, when n is 1, L represents a hydrogen atom, and when n is 2, L represents a single bond or a divalent linking group. When n is 2, A ₁₀₁ may be the same or different.
Examples of the substituent when the monophenylanthryl group and diphenylanthryl group have a substituent include an alkyl group which may have a substituent, an aryl group which may have a substituent, and the like, and anthracene A phenyl group is preferred because the stability of the thin film can be improved without changing its own HOMO-LUMO energy gap. The substitution position of such substituents is not particularly limited, but the reason that the phenyl group has a substituent can improve the stability of the thin film without changing the energy gap between HOMO-LUMO of anthracene itself. To preferred.
Further, the bonding position of the phenyl group in the monophenylanthryl group and the diphenylanthryl group has a large HOMO-LUMO energy gap and is relatively easy to synthesize. Or it is preferable that it is 10th-position.

In the formula (II), L represents a hydrogen atom, a single bond or a divalent linking group, and the divalent linking group is preferably an arylene group in which an alkylene group or the like may be interposed. Specific examples thereof include ordinary arylene groups such as a phenylene group, a biphenylene group, and an anthrylene group, as well as those in which two or more arylene groups are directly linked, and include a p-phenylene group and 4,4'-biphenylene. A group or the like is preferable because it improves electron mobility.
The arylene group represented by L may be one in which two or more arylene groups are linked via an alkylene group. As the alkylene group, a methylene group, an ethylene group and the like are preferable. Specific examples of such an arylene group are shown in the following formulas (21) and (22).

Since the vapor-deposited film of the compound represented by the above formula (II) is in a stable amorphous state, the film physical properties are good and uniform light emission is possible without unevenness. In addition, it is stable for over 1 year in the atmosphere and does not cause crystallization.
Among the compounds represented by the formula (II), the compound represented by the formula (II-1) or (II-2) is more preferable because the stability of the thin film is particularly high.

In formula (II-1), M ₁ and M ₂ each independently represent an alkyl group, a cycloalkyl group, an aryl group, or an alkenyl group.
The alkyl group represented by M ₁ and M ₂ may be linear or branched, but an alkyl group that may have a substituent having 1 to 10 carbon atoms is formed by vapor deposition. Is preferable, and an alkyl group which may have 1 to 4 substituents is more preferable. Particularly, an unsubstituted alkyl group having 1 to 4 carbon atoms is preferable because it is easy to form a film by vapor deposition. Specific examples thereof include a methyl group, an ethyl group, an (n-, i-) propyl group, (n -, I-, s-, t-) butyl group and the like.
Examples of the cycloalkyl group represented by M ₁ and M ₂ include a cyclohexyl group and a cyclopentyl group.

As the aryl group represented by M ₁ and M ₂ , those having 6 to 20 carbon atoms are preferable because they can be easily formed by vapor deposition, and further have a substituent such as a phenyl group or a tolyl group. It may be. Specific examples thereof include a phenyl group, (o-, m-, p-) tolyl group, pyrenyl group, naphthyl group, anthryl group, biphenyl group, phenylanthryl group, and tolylanthryl group.
As the alkenyl group represented by M ₁ and M ₂ , those having a total carbon number of 6 to 50 are preferable because they are easy to form by vapor deposition and the stability of the thin film is high. However, it may have a substituent, and preferably has a substituent from the viewpoint of chemical stability. As the substituent at this time, an aryl group such as a phenyl group is preferable because the stability can be improved without affecting the electron transport property. Specific examples thereof include a triphenyl vinyl group, a tolyl vinyl group, and a tribiphenyl vinyl group.

In the formula (II-1), q1 and q2 each represent 0 or an integer of 1 to 5, and particularly preferably 0 or 1 for the reason that the synthesis is easy. When q1 and q2 are each an integer of 1 to 5, particularly 1 or 2, M ₁ and M ₂ are an alkyl group, an aryl group, and an alkenyl group, respectively, and localization of electrons in the molecule Therefore, it is difficult to interact with other materials, and high electron mobility can be obtained.
Differ in the formula (II-1), when may be different even in the same and _{M 1} and _{M 2,} and the _{M 1} and _{M 2} present in plural, _{M 1} each other, _{M 2} each other, and each of the same M ₁ or M ₂ may be bonded to form a ring such as a benzene ring.
In the formula (II-1), L ₁ represents a hydrogen atom, a single bond or an arylene group. The arylene group represented by L ₁ has the same meaning as L in formula (II).

Next, formula (II-2) will be described. M ₃ and M ₄ are M ₁ and M ₂ in formula (II-1), q3 and q4 are q1 and q2 in formula (II-1), further _{L 2} are each as _{L 1} synonymous in the formula (II-1), preferable ones are also same.
Differ in the formula (II-2), may be different even in the same and _{M 3} and _{M 4, when M 3} and _{M 4} are present in plural, _{M 3} each other, _{M 4} each other, in each of the same M ₃ or M ₄ may be bonded to each other to form a ring such as a benzene ring.
In the formula (II-2), L ₂ represents a hydrogen atom, a single bond or an arylene group. The arylene group represented by L ₂ has the same meaning as L in formula (II).

In formula (IIIa), Q ¹⁰ , Q ²⁰ , Q ³⁰ , Q ⁴⁰ , Q ⁵⁰ , Q ⁶⁰ , Q ⁷⁰ , Q ⁸⁰ , Q ¹¹⁰ , Q ¹²⁰ , Q ¹³⁰ and Q ¹⁴⁰ are each independently a hydrogen atom, alkyl A group, an aryl group, an alkenyl group, an aralkyl group, an alkoxy group and an amino group;

In formula (IIIa), Q ¹⁰ , Q ²⁰ , Q ³⁰ and Q ⁴⁰ (hereinafter referred to as Q ^{10 to} Q ⁴⁰ ) are any of a hydrogen atom, an alkyl group, an aryl group and an alkenyl group. This is preferable because it is difficult to localize electrons in the substrate and interaction with other materials hardly occurs, and an aryl group is more preferable. In particular, Q ¹⁰ and Q ⁴⁰ are each a hydrogen atom and Q ²⁰ and Q ³⁰ are the above substituents, which is preferable because it improves the molecular property and improves the electron mobility.
In addition, Q ¹⁰ and Q ⁴⁰ , and Q ²⁰ and Q ³⁰ are preferably the same from the reason that the molecular property is maintained and the electron mobility is improved, but they may be different.
Q ⁵⁰ , Q ⁶⁰ , Q ⁷⁰ and Q ⁸⁰ (hereinafter referred to as Q ^{50 to} Q ⁸⁰ ) are any one of a hydrogen atom, an alkyl group, an aryl group, and an alkenyl group. It is preferable for the reason of maintaining and improving the mobility of electrons, and particularly preferably a hydrogen atom or an aryl group. Further, Q ⁵⁰ and Q ⁶⁰ , and Q ⁷⁰ and Q ⁸⁰ are preferably the same, but may be different.
Further, Q ¹¹⁰ , Q ¹²⁰ , Q ¹³⁰ and Q ¹⁴⁰ (hereinafter referred to as Q ^{110 to} Q ¹⁴⁰ ) are preferably hydrogen atoms.

Alkyl group represented by ^{Q 10 ~Q 40, Q 50 ~Q} 80 and ^Q 110 ^{to Q 140} may be substituted for the reason that the film formation is easy by vapor deposition, carbon atoms The thing of 1-6 is preferable and may be linear or may have a branch. Preferable specific examples of the alkyl group include a methyl group, an ethyl group, a (n, i) -propyl group, a (n, i, sec, tert) -butyl group, a (n, i, neo, tert) -pentyl group, and the like. Is mentioned.
The aryl group represented by Q ^{10 to} Q ⁴⁰ , Q ^{50 to} Q ⁸⁰ and Q ^{110 to} Q ¹⁴⁰ may be monocyclic or polycyclic, and includes a condensed ring. A total carbon number of 6 to 30 is preferable because it is easy to form a film by vapor deposition, and may have a substituent. The aryl group represented by ^{Q 10 ~Q 40, Q 50 ~Q} 80, Q 110 ~Q 140, preferably a phenyl group, (o-, m-, p-) tolyl group, pyrenyl group, perylenyl group, Examples include a coronenyl group, (1- and 2-) naphthyl group, anthryl group, (o-, m-, p-) biphenylyl group, terphenyl group, and phenanthryl group.

The alkenyl group represented by ^{Q 10 ~Q 40, Q 50 ~Q} 80 and ^Q 110 ^{to Q 140,} having a phenyl group in at least one of the substituents (1 and 2) phenylalkenyl group, ( 1,2- and 2,2-) diphenylalkenyl groups, (1,2,2-) triphenylalkenyl groups and the like are preferred, but may be unsubstituted.
The aralkyl groups represented by Q ^{10 to} Q ⁴⁰ , Q ^{50 to} Q ⁸⁰ and Q ^{110 to} Q ¹⁴⁰ may have a substituent, and those having a total carbon number of 7 to 30 can be easily formed by vapor deposition. It is preferable because of the above, and specific examples thereof include a benzyl group and a phenethyl group.
Two or more of these substituents may form a condensed ring. Further, it may be further substituted, and preferred substituents in that case are the same as described above.

When Q ^{10 to} Q ⁴⁰ , Q ^{50 to} Q ^80, and Q ^{110 to} Q ¹⁴⁰ have a substituent, it is particularly preferable that at least two of Q ^{10 to} Q ⁴⁰ have the substituent as described above. This is preferable because the system is expanded and high electron mobility can be obtained. The substitution position is not particularly limited, and when Q ^{10 to} Q ⁴⁰ have a phenyl group, any of the meta, para, and ortho positions may be used.
In the formula (IIIa), it is a molecule that at least one of Q ^{10 to} Q ⁴⁰ and Q ^{50 to} Q ⁸⁰ , or at least one of Q ^{10 to} Q ⁴⁰ is a substituted or unsubstituted aryl group. This is preferable because it increases the conjugation of the compound and hardly interacts with other materials.
In particular, as a compound represented by the formula (IIIa), a compound represented by the following formula (III-1) has a relatively large HOMO-LUMO energy gap and is preferable for obtaining green to yellow light emission. The compound represented by the formula (III-2) is preferable for obtaining yellow to red light emission. First, Formula (III-1) will be described.

In formula (III-1), Q ^{5 to} Q ⁸ and Q ^{11 to} Q ¹⁶ each independently represent a hydrogen atom, an alkyl group, an aryl group, an alkenyl group, an aralkyl group, or a heterocyclic group, which are the same or different. It may be. Q ^{21 to} Q ²⁵ and Q ^{51 to} Q ⁵⁵ each independently represent a hydrogen atom, an alkyl group, an aryl group, an alkenyl group, or an aralkyl group, which may be the same or different and are adjacent to each other. Two or more of them may be bonded to each other to form a ring.
Specific examples of these groups include those having the same meaning as Q ^{10 to} Q ^{40 in} formula (IIIa).

In the formula (III-1), Q ^{51 to} Q ⁵⁵ and Q ^{21 to} Q ²⁵ are any one of a hydrogen atom, an aryl group, and an alkenyl group, and the localization of electrons in the molecule hardly occurs. An aryl group is preferable because it is difficult to interact with the material. Moreover, it is preferable to have an aryl group as a substituent in at least one of these groups because the molecular conjugated system can be expanded and high electron mobility can be obtained. Two or more adjacent ones of these may form a condensed ring. A preferred embodiment of the aryl group is the same as Q ^{10 to} Q ⁴⁰ described above.

Examples of the condensed ring formed include indene, naphthalene, anthracene, and phenanthrene.
Q ^{5 to} Q ⁸ in the formula (III-1) have the same meanings as Q ^{50 to} Q ⁸⁰ in the formula (IIIa). The hydrogen atom is particularly preferable as ^Q 11 ^{to Q 16.}

Wherein ^{(III-2), Q 5} ~Q 8, Q 11 ~Q 14, Q 31 ~Q 35, Q 41 ~Q 45, Q 61 ~Q 65, Q 71 ~Q 75 is Q of formula (IIIa) ^It is synonymous with ¹⁰ mag.
In formula (III-2), Q ^{71 to} Q ⁷³ , Q ^{61 to} Q ⁶³ , Q ^{31 to} Q ³³ and Q ^{41 to} Q ⁴³ are preferably any one of a hydrogen atom, an aryl group and an alkenyl group, particularly An aryl group is preferable. In addition, at least one of these groups preferably has an aryl group as a substituent, and particularly preferably an aryl group. Two or more of these may combine to form a ring. A preferred embodiment of the aryl group is the same as Q ^{10 to} Q ⁴⁰ in formula (IIIa). Further, Q ^{71 to} Q ⁷³ and Q ^{41 to} Q ⁴³ , Q ^{61 to} Q ⁶³ and Q ^{31 to} Q ³³ are preferably the same, but may be different.
Examples of the ring formed include indene, naphthalene, anthracene, phenanthrene and the like.
Q ^{5 to} Q ⁸ in the formula (III-2) are synonymous with Q ^{50 to} Q ⁸⁰ in the formula (IIIa), and Q ^{11 to} Q ¹⁴ , Q ⁷⁴ , Q ⁷⁵ , Q ⁶⁴ , Q ⁶⁵ , Q ⁴⁴ , Q ⁴⁵ , Q ³⁴ and Q ³⁵ are preferably hydrogen atoms.

R ₃₁ is a group represented by the above formula (11), and R ₃₂ is a group represented by the above formula (12). m1 represents 0 or an integer of 1 to 2, m2 represents an integer of 1 to 3, and m1 + m2 is 3.
When m1 is 2, R ₃₁ may be the same as or different from each other. When m2 is 2 or 3, R ₃₂ may be the same as or different from each other.

R ₆₁ represents a hydrogen atom or an aryl group. The aryl group represented by R ₆₁ may have a substituent, and those having a total carbon number of 6 to 30 are preferable because the film formation by vapor deposition is easy, and examples thereof include a phenyl group. .

R ₆₂ and R ₆₃ each represent a hydrogen atom, an aryl group or an alkenyl group, and these may be the same or different.
The aryl group represented by R ₆₂ and R ₆₃ may have a substituent, and those having a total carbon number of 6 to 70 are preferable because film formation by vapor deposition is easy. Specific examples thereof include a phenyl group, a naphthyl group, an anthryl group, and the like. As a substituent, an arylamino group (for example, a diphenylamino group), an arylaminoaryl group, and the like increase the fluorescence intensity and improve the hole trapping property. It is preferable because of its high efficiency. Such a substituent includes a styryl group (the styryl group may further have a substituent such as a phenyl group, a diphenylamino group, a naphthyl (phenyl) amino group, a diphenylaminophenyl group). It is also preferable. In such a case, it is also preferable that the monovalent groups derived from the compound represented by the formula (IV) have a structure in which they are bonded by themselves or via a linking group.
The alkenyl group represented by R ₆₂ and R ₆₃ may have a substituent, and those having a total number of carbon atoms of 2 to 50 are preferable because film formation by vapor deposition is easy, and examples thereof include a vinyl group. And preferably forms a styryl group together with a vinyl group, and the styryl group may have a substituent such as an arylaminoaryl group (for example, diphenylaminophenyl group) or an arylamino group (for example, diphenylamino group). Good. In such a case, it is also preferable that the monovalent groups derived from the compound represented by the formula (IV) have a structure in which they are bonded by themselves or via a linking group.

R ₆₅ represents an aryl group, an alkyl group, an amino group, an arylamino group or an arylaminoaryl group, and these include a styryl group (the styryl group may further have a substituent such as a phenyl group). Also good. In such a case, it is also preferable that the monovalent groups derived from the compound represented by the formula (IV) have a structure in which they are bonded by themselves or via a linking group.
v2 represents an integer of 0 or 1 to 5, when v2 is 2 or more, attached R ₆₅ together with each other to form a benzene ring or the like, may become a condensed ring.

R ₆₆ and R ₆₇ each independently represents an alkyl group or an aryl group.
The alkyl group represented by R ₆₆ and R ₆₇ may have a substituent, may be linear or branched, and has a total carbon number of 1 to 6 as a film formed by vapor deposition. Is preferable because of its ease, and specific examples thereof include a methyl group and an ethyl group.
The aryl group represented by R ₆₆ and R ₆₇ may have a substituent, may be monocyclic or polycyclic, and those having a total carbon number of 6 to 20 can be easily formed by vapor deposition. It is preferable for the reason, and specific examples thereof include a phenyl group.
v _{3, v 4} is an integer of 0 or 1 to 4.

v ₅ represents 0 or 1. Among the formulas (IV), the diphenylamino group that v ₅ is 0 and R ₆₅ may be bonded to the vinyl group to which R ₆₁ , R ₆₂ , and R ₆₃ are bonded is a para group with respect to the phenylene group. A structure bonded so as to be in a position is preferable because a strong tendency strength can be obtained by expanding the conjugated system of the whole molecule.
Among the styryl-based amine compounds represented by the formula (IV), the reason why the compounds represented by the following formulas (IV-1) and (IV-2) widen the conjugated system of the whole molecule and provide a strong tendency strength. To more preferable.

Wherein _{(IV-1), R 61} , R 62 have the same meanings as those in formula _{(12), R 64, R} 65 has the same meaning as _{R 65} in the formula _{(11), v 1, v} 2 Is synonymous with V ₂ in Formula (11), n1 represents 0 or 1, and L ₆₁ represents a bond or an arylene group. Preferable specific examples of the arylene group include a phenylene group, a biphenylene group, a naphthylene group, an anthrylene group, and the like. A combination thereof is also preferable, and these groups may further have a substituent.
In formula (IV-2), R _{61 to} R ₆₃ , R ₆₅ and v ₂ are the same as those in formula (IV-1), n2 represents 0 or 1, and L ₆₂ represents formula (IV). the same meaning as _{L 61} in the IV-1) in.

In the formula (V), Z _{1 to} Z ₆ , Z _{9 to} Z ₁₀ , Z _{11 to} Z ₁₆ , Z ₁₉ and Z ₂₀ are a hydrogen atom, a halogen atom, a linear chain which may have a substituent, branched or A cyclic alkyl group, a linear, branched or cyclic alkoxy group which may have a substituent, a linear, branched or cyclic alkylthio group which may have a substituent, and a substituent. A linear, branched or cyclic alkenyl group which may have a substituent, a linear, branched or cyclic alkenyloxy group which may have a substituent, a linear, branched or cyclic alkenylthio which may have a substituent Group, an aralkyl group which may have a substituent, an aralkyloxy group which may have a substituent, an aralkylthio group which may have a substituent, and an aryl which may have a substituent Group, aryloxy group optionally having substituent (s), An arylthio group which may have a substituent, an arylalkenyl group which may have a substituent, an alkenylaryl group which may have a substituent, an amino group which may have a substituent, A cyano group, a hydroxyl group, a -COOR ₁₀₀ group (wherein R ₁₀₀ is a hydrogen atom, a linear chain optionally having substituents, a branched or cyclic alkyl group, a linear chain optionally having substituents, A branched or cyclic alkenyl group, an aralkyl group which may have a substituent, or an aryl group which may have a substituent, -COR ₂₀₀ group (in the group, R ₂₀₀ is a hydrogen atom, substituted) Linear, branched or cyclic alkyl group which may have a group, linear, branched or cyclic alkenyl group which may have a substituent, aralkyl group which may have a substituent, substituted Aryl group optionally having a group Or an amino group), or -OCOR 300 _(in group, R ₃₀₀ represents a linear may have a substituent group, branched or cyclic alkyl group, which may have a substituent a straight chain, branched Or a cyclic alkenyl group, an aralkyl group which may have a substituent, or an aryl group which may have a substituent), and further from an adjacent group selected from Z _{1 to} Z ₂₀ The selected groups may be bonded to each other to form an optionally substituted carbocyclic aliphatic ring, aromatic ring or condensed ring together with the substituted carbon atom.
In addition, an aryl group shows heterocyclic aromatic groups, such as carbocyclic aromatic groups, such as a phenyl group and a naphthyl group, a furyl group, a thienyl group, and a pyridyl group.

In general formula (V), a linear, branched or cyclic alkyl group of Z _{1 to} Z _20, a linear, branched or cyclic alkoxy group, a linear, branched or cyclic alkylthio group, linear, branched or The cyclic alkenyl group, the linear, branched or cyclic alkenyloxy group, and the linear, branched or cyclic alkenylthio group may have a substituent, for example, a halogen atom or an aryl having 4 to 20 carbon atoms. Group, C1-C20 alkoxy group, C2-C20 alkoxyalkoxy group, C2-C20 alkenyloxy group, C4-C20 aralkyloxy group, C5-C20 aralkyloxyalkoxy Group, aryloxy group having 3 to 20 carbon atoms, aryloxyalkoxy group having 4 to 20 carbon atoms, arylalkenyl group having 5 to 20 carbon atoms, aralkyl having 6 to 20 carbon atoms Alkenyl group, C1-C20 alkylthio group, C2-C20 alkoxyalkylthio group, C2-C20 alkylthioalkylthio group, C2-C20 alkenylthio group, C4-C20 aralkylthio Group, aralkyloxyalkylthio group having 5 to 20 carbon atoms, aralkylthioalkylthio group having 5 to 20 carbon atoms, arylthio group having 3 to 20 carbon atoms, aryloxyalkylthio group having 4 to 20 carbon atoms, and 4 to 20 carbon atoms The arylthioalkylthio group, a C4-C20 heteroatom-containing cyclic alkyl group, or a halogen atom may be monosubstituted or polysubstituted. Furthermore, the aryl group contained in these substituents further includes a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an aryl group having 3 to 10 carbon atoms, and an aryl group having 4 to 10 carbon atoms. It may be substituted with an aralkyl group.

In the general formula (V), the aryl group in Z _{1 to} Z _{20 in} the aralkyl group, aralkyloxy group, aralkylthio group, aryl group, aryloxy group, and arylthio group may have a substituent. , An alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aralkyl group having 4 to 20 carbon atoms, an aryl group having 3 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and 2 to 2 carbon atoms 20 alkoxyalkyl groups, C2-C20 alkoxyalkyloxy groups, C2-C20 alkenyloxy groups, C3-C20 alkenyloxyalkyl groups, C3-C20 alkenyloxyalkyloxy groups, Aralkyloxy group having 4 to 20 carbon atoms, Aralkyloxyalkyl group having 5 to 20 carbon atoms, Aralkyloxyalkyl having 5 to 20 carbon atoms Xoxy group, C3-C20 aryloxy group, C4-C20 aryloxyalkyl group, C4-C20 aryloxyalkyloxy group, C2-C20 alkylcarbonyl group, C3-C3 20 alkenylcarbonyl groups, 5 to 20 carbon atoms aralkylcarbonyl groups, 4 to 20 carbon atoms arylcarbonyl groups, 2 to 20 carbon atoms alkoxycarbonyl groups, 3 to 20 carbon atoms alkenyloxycarbonyl groups, 5 carbon atoms -20 aralkyloxycarbonyl group, C4-20 aryloxycarbonyl group, C2-20 alkylcarbonyloxy group, C3-20 alkenylcarbonyloxy group, C5-20 aralkyl A carbonyloxy group, an arylcarbonyloxy group having 4 to 20 carbon atoms, an alkyl having 1 to 20 carbon atoms Ruthio group, C 4-20 aralkylthio group, C 3-20 arylthio group, nitro group, cyano group, formyl group, halogen atom, halogenated alkyl group, hydroxyl group, amino group, C 1-20 It may be monosubstituted or polysubstituted by a substituent such as an N-monosubstituted amino group or an N, N-2 substituted amino group having 2 to 40 carbon atoms.
Furthermore, the aryl group contained in these substituents further includes a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an aryl group having 7 to 10 carbon atoms. It may be substituted with an aralkyl group.

In formula _(V), the amino group of Z 1 _{to Z 20} may have a substituent, for example, an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 4 to 20 carbon atoms or 3 carbon atoms, It may be monosubstituted or disubstituted with ˜20 aryl groups.
In the general formula (V), the alkyl group, alkenyl group, aralkyl group and aryl group of R ₁₀₀ , R ₂₀₀ and R ₃₀₀ may have a substituent, for example, the substituents exemplified for Z _{1 to} Z _20. May be mono- or polysubstituted.

Z _{1 to} Z ₂₀ are preferably Z ₅ , Z ₆ , Z ₉ , Z ₁₀ , Z ₁₅ , Z ₁₆ , Z ₁₉ and Z ₂₀ are hydrogen atoms, and Z _{1 to} Z ₄ , Z _{11 to} Z ₁₄ is a hydrogen atom, a halogen atom, a linear, branched or cyclic alkyl group having 1 to 24 carbon atoms which may have a substituent, and a carbon atom having 1 to 24 carbon atoms which may have a substituent. Straight, branched or cyclic alkoxy group, optionally having a straight chain, branched or cyclic alkenyl group, alkenyl aryl group, aryl alkenyl group, substituent having a total carbon number of 2 to 24 An aralkyl group having 7 to 24 carbon atoms which may be substituted, an aryl group having 6 to 24 carbon atoms which may have a substituent, a cyano group, a heterocyclic group, a hydroxyl group, -COOR ₁₀₀ , -COR ₂₀₀ Or -OCOR ₃₀₀ (provided that R _{10 in} the group _{0 to} R ₃₀₀ are as defined above.
Further, adjacent groups selected from Z _{1 to} Z ₂₀ are bonded or condensed to each other, and together with the substituted carbon atom, an optionally substituted carbocyclic aliphatic ring, aromatic ring, or A condensed ring may be formed.

  In formula (VII), Y1 to Y14 represent an alkyl group, an aryl group, an amino group, an alkoxy group, or an aryloxy group, and these may be further substituted. Also preferred are those in which at least one of Y1 to Y14 is substituted with an aryl group or an arylamino group.

  The light emitting layer is represented by the above formula (I), (II), (IIIa) or (VI) because various emission colors can be obtained without changing the electrical characteristics and stability of the device. It is also preferable that each of the first compound and at least one second compound represented by the formula (IIIa), (IV), (V), or (VII) is included. In this case, it is preferable to form a doped light emitting layer in which the first compound is used as a host material and the second compound is used as a light emitting dopant material. Here, the host material occupies a large part of the composition of the light emitting layer, and mainly means a material having a function as a carrier transport material, a function as a recombination center, and a function of propagating recombination energy to a dopant. . The light-emitting dopant material has a lower content in the light-emitting layer than the host material, has a function of trapping carriers, a function as a recombination center, and a function of emitting light in an excited state by receiving recombination energy from the host material. Means a substance. The content of the dopant material relative to the host material is not particularly limited as long as it is an amount sufficient to receive the recombination energy of the host and does not cause concentration quenching. 50 mass% is preferable, 0.5-20 mass% is further more preferable, and 1-10 mass% is especially preferable. In order to obtain a blue or cyan light emitting layer, the host material contains at least one compound represented by the above formula (I) and / or (II), and the light emitting dopant material is represented by the above formula (IV). It is preferable that at least one compound represented by the formula is included, and in order to obtain a green light emitting layer, at least one compound represented by the above formula (I) and / or (II) and / or (VI) is used as a host material. And at least one compound represented by (IIIa) as a light-emitting dopant substance, and a substance represented by the above formula (I) and / or (IIIa) as a host substance in order to obtain a red light-emitting layer It is preferable to contain at least one compound represented by the above formula (V) as a light-emitting dopant substance. In order to obtain a yellow to orange light emitting layer, the host material contains at least one compound represented by the above formulas (I), (II) and (VI), and the light emitting dopant contains the above formula (IIIa) or (VII). It is preferable that at least one compound represented by

Particularly preferred host material and dopant material pairs are as shown in Table 1.

From the viewpoint of obtaining a desired emission color, it is preferable that a blue light emitting layer, a green light emitting layer, and a red light emitting layer are arranged with an intermediate layer interposed therebetween.
The light emitting layer is also preferably arranged with a cyan light emitting layer and a yellow light emitting layer sandwiching an intermediate layer from the viewpoint of obtaining a desired light emitting color.
Further, a light emitting layer in which light emitting layers emitting blue, green, and red light are laminated is further laminated through an intermediate electrode, or a light emitting layer in which light emitting layers emitting cyan and yellow light are laminated. It may be in a form of being further laminated via an intermediate electrode.

  The electron injection / transport layer 43 is a layer having a function of facilitating injection of electrons from the intermediate electrode 5, a function of transporting electrons, and a function of hindering transport of holes. The material used for the electron injecting and transporting layer 43 includes an anthracene derivative, a naphthacene derivative, a fluoranthene derivative, an organic material having a quinolinol ring such as tris (8-quinolinolato) aluminum, or an organic metal coordinated with an organic material having a quinolinol ring. Quinoline derivatives such as complexes, oxadiazole derivatives, pyridine derivatives, pyrimidine derivatives, quinoline derivatives, quinoxaline derivatives, diphenylquinone derivatives, perylene derivatives, nitro-substituted fluorene derivatives, anthraquinodimethane and its derivatives, benzoquinone and its derivatives, naphthoquinone and Its derivatives, anthraquinone and its derivatives, tetracyanoanthraquinodimethane and its derivatives, fluorene and its derivatives, diphenyldicyanoethylene and its derivatives, phenanthate Phosphorus and its derivatives, as well as a metal complex of these compounds as a ligand. Examples of the electron transporting polymer material include polyquinoxaline and polyquinoline.

  The electron injecting and transporting layer 43 is provided as necessary in consideration of the height of each function of electron injection and electron transport of the compound used for the light emitting layer 42. For example, when the compound used for the light emitting layer 42 has a high electron injecting and transporting function, the light emitting layer 42 can also serve as the electron injecting and transporting layer 43 without providing the electron injecting and transporting layer 43. The electron injecting and transporting layer 43 may be separately provided in a layer having an injection function and a layer having a transport function.

  The intermediate electrode 5 includes at least one metal film. In the present embodiment, the intermediate electrode 5 includes a layer 51 containing an alkali metal or an alkaline earth metal, a metal film 52, and an electron accepting layer 53.

  The layer 51 containing an alkali metal or an alkaline earth metal is a layer having a function of supporting electron injection. By providing the layer 51 containing an alkali metal or alkaline earth metal on the anode 3 side of the metal film 52, the light emission intensity can be improved and the light emission efficiency can be increased. Examples of the material used for the layer 51 containing an alkali metal or an alkaline earth metal include Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, and Ra. These alkali metals and alkaline earth metals may be used alone, but contain an organic compound that forms a radical anion or a charge transfer complex upon receiving an electron donation from these alkali metals or alkaline earth metals. Also preferred is. Examples of such organic compounds include organic materials having a quinolinol ring such as tris (8-quinolinolato) aluminum, or organometallic complexes coordinated with an organic material having a quinolinol ring, and oxadiazole derivatives, pyridine derivatives, and pyrimidines. And heterocyclic compounds such as derivatives, quinoline derivatives, quinoxaline derivatives, and phenanthroline derivatives.

Further, instead of the layer 51 containing the alkali metal or alkaline earth metal of the intermediate electrode 5, a layer containing a compound containing alkali metal ions or alkaline earth metal ions may be formed. Also in this case, the same effect as the layer 51 containing an alkali metal or an alkaline earth metal can be obtained. Examples of compounds containing such alkali metal ions or alkaline earth metal ions include alkali metal halides, alkaline earth metal halides, alkali metal oxides, alkaline earth metal oxides, alkali metal chalcogenides, alkaline earths. Inorganic materials such as alkali metal chalcogenides, or alkali metal alkoxides, alkaline earth metal alkoxides, alkali metal aryloxides, alkaline earth metal aryloxides, and organometallic complexes mainly composed of alkali metals, mainly alkaline earth metals Examples include metal-organic organometallic complexes, and specific examples include LiF, MgF, and Li quinolinol. These compounds containing alkali metal ions or alkaline earth metal ions may be used alone, but organic compounds that form a radical anion or a charge transfer complex upon receiving an electron donation from an alkali metal or alkaline earth metal The case where it contains simultaneously is also preferable. Examples of such organic compounds include organic materials having a quinolinol ring such as tris (8-quinolinolato) aluminum, or organometallic complexes coordinated with an organic material having a quinolinol ring, and oxadiazole derivatives, pyridine derivatives, and pyrimidines. And heterocyclic compounds such as derivatives, quinoline derivatives, quinoxaline derivatives, and phenanthroline derivatives.
Further, the layer 51 or the electron accepting layer 53 containing an alkali metal or an alkaline earth metal may not be formed on the intermediate electrode 5. Also in this case, the luminous efficiency of the organic EL element 1 to be formed can be improved, and an increase in the driving voltage of the element can be suppressed.

  The metal film 52 is a discontinuous film containing a metal in which particles grow in a columnar shape. FIG. 2A shows a diagram for explaining the structure of the metal film 52. For comparison, FIG. 2B shows a diagram for explaining the structure of a conventional island-shaped metal film.

  As shown in FIG. 2A, the metal contained in the metal film 52 grows in a columnar shape so that the metal crystal extends in the vertical direction with respect to the substrate as the film thickness increases. For this reason, even if the thickness of the metal film 52 increases, the light transmittance does not decrease. Further, the insulation in the film surface direction is maintained. On the other hand, as shown in FIG. 2B, in the conventional island-shaped metal film, when the film thickness increases, the metal crystal increases in a planar shape in the horizontal direction with respect to the substrate. As a result, the light transmittance is greatly reduced. Furthermore, when the film thickness is 10 nm or more, light is hardly transmitted and the insulation in the film surface direction is further deteriorated. As described above, the metal film 52 of the present invention is a discontinuous film containing a metal in which particles grow in a columnar shape. Even when the film thickness is increased, the light transmittance does not decrease, and the insulation in the film surface direction is obtained. Maintained.

  As such a metal film 52, for example, a mixed film containing aluminum and indium is preferably used. This is because when the film thickness of the mixed film containing aluminum and indium is increased, aluminum metal crystals are likely to grow in a columnar shape, the light transmittance is not lowered, and the insulation in the film surface direction is easily maintained. .

The difference in structure between the columnar growth film and the conventional island-like growth film will be described in more detail.
In the metal film according to the present invention, when the particles grow and come into contact with each other, they recrystallize into a new large spherical structure, so that the individual particles are oriented in the film surface direction (A in FIG. 3). The columnar shape is short in the direction) and long in the direction perpendicular to the film surface (direction B in FIG. 3). Therefore, as shown in FIG. 9B to be described later, when the film thickness is about 4 nm, the porosity is high and the light transmittance is high. In the present invention, even if the film thickness is increased to about 10 nm, the particles grow in the vertical direction with respect to the substrate, and the length in the B direction maintains a large value with respect to the average film thickness. Without discontinuity, the discontinuous film morphology is maintained. Such a discontinuous film state is maintained even when the average film thickness is about 25 nm. In addition, the voids in the grain boundaries are filled with a material of a layer in contact with the metal film.

  The reason why the metal film of the present invention grows such a crystal is thought to be because Al and In are difficult to form a solid solution. That is, Al must grow a crystal while removing In from the crystal. Therefore, in the conventional island-shaped film, when Al particles grow and come into contact with each other, they join at the particle interface, whereas in the columnar film of the present invention, the entire particle is recrystallized and grown and stabilized. It is thought that. Therefore, the metal film of the present invention is not a mere alloy film of Al and In but has a special structure in which In is segregated around Al columnar particles. Also, Al columnar particles themselves are much higher in crystallinity than conventional Al island-like particles. The high light transmittance and high insulation in the film surface direction of the metal film of the present invention are due to such structural features. The reason for the high light transmittance is that light can be transmitted through the voids of the columnar particles, but another reason is that In is segregated on the surface of the Al particles, the surface of the Al particles. It is also considered that plasmon absorption in can be suppressed. In addition, the reason for exhibiting high insulation in the direction of the film surface is that the voids between the metal particles insulate the metal particles, while the crystallinity of the individual metal particles is very good, One of the major features of the metal film of the present invention is that it exhibits anisotropic conductivity with high conductivity in the film thickness direction. Due to this feature, such as off-dot light emission and crosstalk when a display is produced. Problems can be prevented.

  It can be observed from the TEM image or STEM image from the film surface direction and the cross-sectional direction that the metal film of the present invention is in such a form. It can also be confirmed that such a structure is obtained by confirming the resistance value in the film surface direction. In a general metal film, lateral conduction can be confirmed with a thickness of 5 to 10 nm. This indicates that the island-like particles are bonded with a film thickness of 5 to 10 nm to form a continuous film. On the other hand, in the metal film of the present invention, lateral conduction cannot be obtained even when the film thickness is increased to 25 nm. This indicates that even when the metal film of the present invention is thickened, the shape of the discontinuous film having voids is maintained. In addition, in the case of an element having an intermediate electrode layer as in this embodiment, since light emission outside the dot is seen if the insulation in the lateral direction cannot be maintained, the element as in this embodiment is created to check whether or not there is light emission outside the dot. It can be confirmed that a discontinuous film having voids is also formed. The high crystallinity of the metal film can be confirmed by X-ray diffraction, electron beam diffraction, or the like.

On the other hand, in the case of the island-shaped growth film of the prior art, when the film thickness increases and the particles grow and the particles come into contact with each other, the particles grow while filling the grain boundaries in a state of being aligned along the film surface. To do. Therefore, as the film thickness increases, the individual particles are longer in the film surface direction (A direction in FIG. 4) and shorter in the vertical direction (B direction in FIG. 4) than the film surface. It becomes the shape of. Although such an island-like growth film maintains a discontinuous film state up to about 4 nm as shown in FIG. 10 described later, the length in the B direction with respect to the average film thickness is more than that of the metal film of the present invention. Since it shows a small value, the porosity of the grain boundary is low, and the light transmittance is remarkably low. When the film thickness is further increased to about 10 nm, the island-like particles are further bonded to form a uniform continuous film. At this stage, the average film thickness substantially coincides with the film thickness in the B direction. Note that when Al and In are present in a material ratio in the range shown in the present invention, such a structure is self-organized regardless of the film formation method, and thus the film formation method is limited to the method shown in this embodiment mode. However, it is particularly preferable to use the resistance heating vapor deposition method from the viewpoint that damage to the element during film formation can be reduced as compared with sputtering or electron beam vapor deposition. Also, from the viewpoint of supplying energy for self-organization of the film as described above, it is preferable to use heat evaporation rather than sputter film formation, but energy for self-assembly can be supplied from other than the evaporation source. However, the film formation is not limited to this in a rough environment.
As described above, the structural characteristics of the metal film of the present invention can greatly improve the light transmittance of the intermediate electrode 5 and ensure high insulation in the film surface direction and high conductivity in the film thickness direction. 5 requires a function of injecting electrons into the organic layer 4 and a function of injecting holes into the organic layer 6 in addition to light transmittance. The metal film of the present invention is also preferable for causing the intermediate electrode 5 to exhibit these functions, and from this point of view, it is particularly preferable to use a mixed film of Al and In.
In order for the intermediate electrode 5 to exhibit an electron injection function, the alkali metal or alkaline earth metal in the layer in contact with the anode side of the metal film must be present stably without being oxidized. When the layer in contact with the anode side of the metal film is a layer containing a compound containing alkali metal ions or alkaline earth metal ions, these alkali metal ions and alkaline earth metal ions are reduced by the reducing function of the metal film 52. It needs to be reduced to alkali metal or alkaline earth metal. The metal film having such a reducing function is limited to a small number of metal species having relatively low light transmittance such as aluminum and magnesium alloy. In addition, even when such a metal having a reducing function is formed in the form of a conventional island film, it has a large specific surface area due to a discontinuous film and is weaker to oxidation than a continuous film. In addition, it is easily lost due to the entry of oxidizing substances from the outside. Therefore, if the conventional island-shaped film is thinned to such an extent that light can be transmitted, the function as an electrode is impaired. However, the metal film of the present invention has both such a reducing function and high light transmittance. The reason why the reduction function of Al is not impaired at all despite the fact that the metal film of the present invention is a discontinuous film having voids is that the high crystallinity of Al particles and the effect of Al caused by In segregated on the surface of Al particles. An improvement in oxidation resistance is considered. That is, the reduction function of Al is lost by oxidizing substances such as oxygen and water incorporated during film formation and similar oxidizing substances entering from the outside after film formation, but in the case of the metal film of the present invention, Al crystals Since the structure is very high and the surface is coated with In, such an oxidizing substance is difficult to penetrate into the Al particles. Therefore, it is considered that the oxidation resistance is improved. In this embodiment mode, the layer in contact with the anode side of the metal film is the same regardless of whether it is a layer containing a compound containing alkali metal ions or alkaline earth metal ions or a layer containing alkali metal or alkaline earth metal. The effect is obtained because the metal film of the present invention maintains the function of reducing alkali metal ions and alkaline earth metal ions to generate alkali metal and alkaline earth metal even in a discontinuous film state. It is shown. In addition, since it has such a reduction function, even when a layer containing an alkali metal and an alkaline earth metal is used as the layer in contact with the anode side of the metal film, the electron injection function is reduced due to the oxidation of the alkali metal or alkaline earth metal. Can be suppressed and durability can be improved.
Next, the hole injection function will be described. In order to develop the hole injection function in the intermediate electrode 5, the electron accepting layer 53 must accept electrons from the hole injecting and transporting layer 61 of the second organic layer 6, and the electrons must be further accepted by the metal film 52. . By using the metal film of the present invention, the energy barrier when the metal film 52 receives electrons from the electron accepting layer 53 can be lowered, so that the intermediate electrode 5 can exhibit high hole injection properties. As a result, low voltage driving is possible. From this point of view, it is preferable that the metal film 52 is a mixed film of Al and In. It is considered that the excellent hole injection function of the metal film of the present invention results from a structure in which the material constituting the electron accepting layer 53 is filled in the voids of the columnar particles of the metal film. That is, in order to improve the hole injection property from the intermediate electrode, it is necessary to donate electrons from the electron accepting layer 53 to the metal film. In the intermediate electrode of the present invention, a part of the material constituting the electron accepting layer 53 is The contact area between the electron-accepting layer 53 and the metal film is very large because it enters the voids of the columnar particles of the metal film. As a result, electrons are transferred with a low interface electric field strength, and it is considered that the energy barrier of the entire interface can be lowered. It is also considered that the crystallinity of individual Al particles is high and the density is high. The reason why the mixed film of Al and In is particularly preferable is that one can form a structure in which the material of the electron accepting layer 53 enters the voids of the metal film, and the other is the LUMO order of the metal film and the metal film. This is because the value of the work function of 52 is close, so that the energy barrier for accepting electrons from the electron accepting layer 53 is particularly low.
As described above, in the metal film of the present invention, the columnar particles are self-organized, and the individual columnar particles have very high crystallinity, so that the light transmission function through the voids, anisotropic electrical conduction, and high oxidation resistance. In addition, it has characteristics that are not found in conventional island films, such as increased contact area with adjacent layers. In addition, by making the metal film a mixed film of Al and In, not only can a columnar structure be easily formed, but also the effect of covering Al particles with In can be obtained, so suppression of plasmon absorption and further oxidation resistance A new function derived from the film structure, which is not found in the Al single film or the In single film, has been developed. Due to the properties unique to the metal film of the present invention, high light transmittance, high insulation in the direction of the film surface, high electron injection property, and high hole injection property can be obtained. An organic EL element that can be driven at a low voltage is high. Further, by creating a display using the element, a high-quality display without off-dot light emission and crosstalk can be created.

  When a mixed film containing aluminum and indium is used for the metal film 52, the mixing ratio of aluminum and indium is preferably 88:12 to 35:65 by weight ratio, and 88:12 to 53: More preferably, it is 47. When the content of indium is less than 12% by weight, the metal particles do not grow in a columnar shape or the effect thereof is insufficient, resulting in an island-like growth film similar to the prior art, and voids between the metal particles. Therefore, the film has a low light transmittance. As a result, the device has low luminous efficiency. This is presumably because the Al particles do not require recrystallization in order to segregate In out of the Al particles because In is a small amount. Therefore, when the indium content is less than 12%, only the properties of Al and In are manifested, and the special effects by mixing as described above are not produced. A film having a high light transmittance can be obtained when the indium content exceeds 65%, but the function of accepting electrons from the electron-accepting layer 53 is reduced, so that the function of injecting holes into the organic layer 2 is reduced. Is damaged. One possible reason for this is an excessive solid solution of In in Al. As described above, Al and In are difficult to dissolve, but when the amount of In with respect to Al becomes excessive, the solid solution of In slightly progresses in the Al particles, thereby causing the crystallinity of the Al particles to increase. It is considered that the exchange of electrons with the electron-accepting layer 53 is hindered due to the damage to the electron. As a result, the device has a high driving voltage and low luminous efficiency. On the other hand, if the In content exceeds 47%, the reducing function for alkali metal ions and alkaline earth metal ions is lowered. As a result, when the layer in contact with the anode side of the metal film is a layer containing alkali metal ions or alkaline earth metal ions, the electron injection function is lowered, the drive voltage is increased, and the light emission efficiency is also lowered. Further, when the layer in contact with the anode side of the metal film is a layer containing an alkali metal or an alkaline earth metal, durability is impaired. The reason for this is considered to be that the reduction function of Al cannot be exhibited because the coating of Al particles with In becomes too thick. As described above, by making the mixing ratio of aluminum and indium within the scope of the present invention, a special function derived from the film structure that is not in the Al single film or the In single film as described above can be obtained. Outside of the scope of the invention, the film simply exhibits both the properties of Al and In.

  The film thickness of the metal film 52 is preferably 1 nm to 25 nm, and more preferably 1 nm to 10 nm. If it is less than 1 nm, the function as an electrode is impaired, and if it exceeds 25 nm, the light transmittance is impaired, which is not preferable. Whereas the metal film of the prior art is 1 nm or more at which the function as an electrode is manifested, the light transmittance sharply decreases, whereas the metal film of the present invention has a range in which the electrode function and the light transmittance are compatible at 1 to 25 nm. In particular, the range of 1 nm to 10 nm is a range in which both light transmittance and the function as an electrode are compatible, and in this film thickness region, the difference from the metal film of the prior art is particularly remarkable. Therefore, by setting the film thickness of the metal film in such a range, the light emission efficiency of the organic EL element 1 to be formed can be increased, the driving voltage can be lowered, and the viewing angle dependence of the organic EL element 1 can be reduced. Can be small.

In addition, the film thickness and the average film thickness as used in the specification are synonymous and are defined as follows.
Film thickness (nm) = Average film thickness (nm) = W (g / nm ² ) / d (g / nm ³ )
W (g / nm ² ) = n (mol / nm ² ) × w (g / mol)
In the formula, W represents the weight of the substance constituting the film existing around the unit area, and d represents the density of the substance constituting the film. N is the number of moles of the substance constituting the film existing per unit area, and w is the atomic weight or molecular weight.

Here, the values of W and n can be measured by quantitatively analyzing the prepared film having a known area, but the analysis range needs to be sufficiently wide with respect to the particle diameter constituting the film, and is 4 mm ² or more. Preferably there is. The method of quantitative analysis in this case is not particularly limited, and for example, techniques such as fluorescent X-ray elemental analysis, ICP emission analysis, ICP mass spectrometry, and atomic absorption analysis can be used.
Further, as another method for obtaining the value of W, a crystal resonator type film thickness meter (crystal sensor) can be used. The quartz oscillator type film thickness meter needs to be calibrated in advance using a step meter or the like, but the sample used for calibration needs to be a thick film that becomes a uniform continuous film. In the case of the metal film of the present invention, 200 nm It is preferable that it is the above film thickness.

  Further, the distance of the metal film in the vertical direction with respect to the substrate when the cross section of the metal film of the present invention is observed by a method such as TEM indicates the length in the vertical direction with respect to the substrate of the metal particles. The definition is different from the film thickness and average film thickness in the book. The length in the vertical direction with respect to the substrate of the particles coincides with the average film thickness in the case of a completely uniform film, but in the case of a film having voids, it becomes a large value with respect to the average film thickness, and the porosity increases. The difference increases.

  The electron-accepting layer 53 is a layer having a function of promoting hole injection. By providing the electron-accepting layer 53 on the cathode 7 side of the metal film 52, the emission intensity can be improved and the emission efficiency can be increased. Examples of the material used for the electron-accepting layer 53 include inorganic materials such as ferric chloride, aluminum chloride, gallium chloride, indium chloride, antimony pentachloride, divanadium pentoxide, tungsten oxide, and molybdenum oxide, pyrazine derivatives, Hexaazatriphenylene derivatives, quinones, or fluoranil, trinitrofluorenone, tetracyanoquinodimethane, hexacyanobutadiene, tetracyanoethylene, tetracyanobenzene, having a substituent having a large electron-accepting property such as a cyano group or a nitro group, Examples include organic materials such as hexacyanohexaazatriphenylene, dimethyltetracyanoquinodimethane, DDQ, and chloranil.

  The second organic layer 6 is made of an organic material having a light emitting function. In the present embodiment, the hole injecting and transporting layer 61, the light emitting layer 62, and the electron injecting and transporting are similar to the first organic layer 4. Layer 63. The configurations of the hole injection / transport layer 61, the light emitting layer 62, and the electron injection / transport layer 63 are the configurations of the hole injection / transport layer 41, the light emitting layer 42, and the electron injection / transport layer 43 of the first organic layer 4. It is the same.

  The cathode 7 is connected to an external power source (not shown) and provides electrons to the organic layer. The cathode 7 preferably uses a metal, an alloy or an electrically conductive compound having a relatively small work function as an electrode material. Examples of the electrode material used for the cathode 7 include lithium, lithium-indium alloy, sodium, sodium-potassium alloy, calcium, magnesium, magnesium-silver alloy, magnesium-indium alloy, indium, ruthenium, titanium, manganese, yttrium, Examples thereof include aluminum, aluminum-lithium alloy, aluminum-calcium alloy, aluminum-magnesium alloy, and graphite thin film. These electrode materials may be used alone or in combination. The cathode 7 can be formed of these electrode materials on the electron injecting and transporting layer by a method such as a vapor deposition method, a sputtering method, an ionized vapor deposition method, an ion plating method, or a cluster ion beam method. Further, the cathode 7 may have a single layer structure or a multilayer structure.

  Here, the distance from the cathode 7 to the intermediate electrode 5 is preferably λ / 2n (λ is the emission wavelength, and n is the refractive index between the cathode and the intermediate electrode). This is because, when the distance from the cathode 7 to the intermediate electrode 5 is λ / 2n, even when the light transmittance of the intermediate electrode 5 is small, the light extraction at a specific emission wavelength λ is improved, and the organic EL element to be formed This is because the luminous efficiency of 1 can be further increased.

  Here, the distance from the cathode 7 to the intermediate electrode 5 is the sum of the film thicknesses of the electron accepting layer 53, the second hole injecting and transporting layer 61, the second light emitting layer 62, and the second electron injecting and transporting layer 63. It is. The refractive index is the refractive index from the cathode 7 to the intermediate electrode 5 when an organic EL element that is a laminate of various materials is constructed, and does not necessarily match the refractive index that is an intrinsic property value of each material. do not do. Therefore, in the case of implementation, by changing the film thicknesses of the electron accepting layer 53, the second hole injecting and transporting layer 61, the second light emitting layer 62, and the second electron injecting and transporting layer 63, a desired wavelength region can be obtained. The distance from the cathode 7 to the intermediate electrode 5 at which the light extraction efficiency is maximized is adjusted. In this case, the wavelength region where the extraction efficiency is improved can be detected by measuring the reflectance spectrum of the element.

  Alternatively, a laminated film of the electron accepting layer 53, the second hole injecting and transporting layer 61, the second light emitting layer 62, and the second electron injecting and transporting layer 63 is formed on a reflective substrate such as silicon, and an ellipsometer is formed. The refractive index n may be measured by In this case, the distance from the cathode 7 to the intermediate electrode 5 at which the extraction efficiency of the desired wavelength region is maximized can be obtained by substituting the measured refractive index n value and desired wavelength value into λ / 2n. .

  Further, the distance from the cathode 7 to the intermediate electrode 5 is set to λ / 2n, and the metal film 52 is made of a mixed film containing aluminum and indium, thereby suppressing light interference and reducing light absorption. it can. As a result, the luminous efficiency of the formed organic EL element 1 can be further increased over a wide wavelength range.

  According to the organic EL element 1 configured in this manner, light from the light emitting layer 42 is transmitted to the outside through the hole injection transport layer 41, the anode 3, and the substrate 2, and at the same time the electron injection transport layer 43. , Passed through the intermediate electrode 5 and the second organic layer 6 and reflected by the cathode 7, and further passed through the second organic layer 6, the intermediate electrode 5, the first organic layer 4, the anode 3 and the substrate 2 to the outside. To be released. In addition, light from the light emitting layer 62 passes through the hole injecting and transporting layer 61, the intermediate electrode 5, the first organic layer 4, the anode 3, and the substrate 2 and is emitted to the outside and the electron injecting and transporting layer 63 It passes through and is reflected by the cathode 7, and further passes through the second organic layer 6, the intermediate electrode 5, the first organic layer 4, the anode 3, and the substrate 2 and is emitted to the outside. In the present embodiment, a discontinuous film containing a metal in which particles grow in a columnar shape is used for the metal film 52 of the intermediate electrode 5, and thus a film thickness that functions as the electrode (1 nm or more, preferably 4 nm). Even in this case, the light transmittance does not decrease, and light emission outside the dots does not occur due to a decrease in insulation in the film surface direction of the metal electrode film. For this reason, the luminous efficiency of the organic EL element 1 can be improved. In addition, an increase in drive voltage of the organic EL element 1 can be suppressed.

  In addition, a first organic layer 4 and a second organic layer 6 having a light emitting function are laminated between the anode 3 and the cathode 7, and the first organic layer 4 and the second organic layer 6 are interposed. Since the intermediate electrode 5 is formed on the substrate, a high-luminance organic EL element 1 can be formed.

  In the above embodiment, the present invention has been described by taking as an example the case where the first organic layer 4, the intermediate electrode 5, and the second organic layer 6 are provided between the anode 3 and the cathode 7. As shown in FIG. 5, the organic layer 4 having a light emitting function and the intermediate electrode 5 may be further laminated. In this case, the organic EL element 1 with higher luminance can be formed.

In the first embodiment, the case where the first organic layer 4 and the second organic layer 6 each having a light emitting function are laminated via the intermediate electrode 5 has been described. For example, a laminated body of an intermediate electrode and an organic layer having a light emitting function may be sandwiched between the second organic layer 6 and the cathode 7.
In addition, from the viewpoint of obtaining a desired emission color, a blue light emitting layer, a green light emitting layer, and a red light emitting layer are arranged with an intermediate layer interposed therebetween, or a cyan light emitting layer and a yellow light emitting material. It is preferable that the layer to be arranged is arranged with the intermediate layer interposed therebetween.
Further, a light emitting layer in which blue, green, and red light emitting layers are laminated is further laminated through an intermediate electrode, or a light emitting layer in which cyan light emitting layer and yellow light emitting layer are laminated. It may be a form in which it is further laminated via an intermediate electrode.

(Second Embodiment)
The present embodiment is the same as the first embodiment except that the metal film 52 is composed of a film containing an amorphous metal (aluminum) (amorphous metal film).
Here, as shown in FIG. 6, the amorphous metal film defined in the present specification does not advance the growth of crystal nuclei even when the film thickness is increased, and a large number of new crystal nuclei are formed. As a result, it refers to a metal film in the form of an aggregate of fine crystals. In such an amorphous metal film, nucleation due to bonding between crystal grains does not occur, so that the film is a sparse film in which fine voids exist between the microcrystals. For this reason, light is transmitted through the fine gap, and the light transmittance does not decrease even when the film thickness is increased. On the other hand, as shown in FIG. 2B, in the conventional island-shaped metal film, when the film thickness is increased, the crystal nuclei are bonded to each other to grow grains, so that the surface is enlarged in the horizontal direction and voids are formed. The light transmittance is reduced.

As such an amorphous metal film, for example, a mixed film containing aluminum and indium is preferably used. It is considered that the reason why the metal film of the present invention forms such an amorphous state is that Al and In are difficult to form a solid solution. That is, if In is present between Al crystal nuclei, the Al crystal nuclei cannot be bonded to each other, and since Al and In are difficult to form a solid solution, the Al crystal nuclei and the In crystal nuclei are bonded. It cannot be done, and it is thought that it exists as a microcrystal.
It can be observed from the TEM image or STEM image from the film surface direction and the cross-sectional direction that the metal film of the present invention has such a form. According to the TEM image or STEM image, In particles can be observed, but the particles are not in contact with each other, and voids exist between the particles. Although there are sites where Al particles are present on the In particles in contact with them, Al particles and grain boundaries are not observed at all between the In particles, and only by elemental analysis (EDS). Since the presence of Al can be confirmed, it can be seen that Al is present in a microcrystalline state. It can also be seen that the In particles and the Al particles that are in contact with the In particles exist as separate particles without being mixed with each other, and Al and In are not in solid solution with each other. The particle diameter of Al microcrystals cannot be measured accurately because it cannot be observed with TEM and STEM, but it is assumed that most Al microcrystals present in the voids of In particles have a particle diameter of 1 nm or less. Further, when electron beam diffraction is measured, Al can be confirmed to be in a microcrystalline state because the crystallinity is low and almost no diffraction lines can be observed. Note that the amorphous film as used in the present invention is not limited to the form in which the above-described characteristics can be observed by TEM and STEM, and microcrystalline Al is present, and from the microcrystalline voids. It means what transmits light. Further, the effect of the present invention can be obtained whether the region occupied by such microcrystalline Al in the film is the entire film or a part of the film.

  Note that a film formation method for obtaining such an amorphous metal film is not limited, but a sputtering method is preferably used. This is because the sputtering method has a smaller thermal energy supplied to the substrate together with the atomic beam than the deposition method by heating such as resistance heating, induction heating, and electron beam deposition, and it is considered that the energy for crystal growth is insufficient. . In the case of the mixed film of Al and In of the present invention, in order for Al grains to bond and grow, In must be eliminated and segregated, and mass transfer energy is required for that purpose. When film formation is performed by sputtering, this mass transfer energy is not supplied, and it is considered that an amorphous metal film is formed.

Here, the columnar film of the first embodiment and the amorphous film of the second embodiment will be compared and described. Both forms are a mixed film of metallic elements such as Al and In that are difficult to form a solid solution with each other, and since Al crystal grains are difficult to bond with each other, they are common in that voids exist between the grains. However, in the case of the columnar film of the first embodiment, there are a small number of relatively large voids, whereas in the case of the amorphous film of the second embodiment, there are a large number of fine voids. However, the light transmission is improved.
That is, if Al and In are present in a material ratio in the range shown in the present invention, a film having voids can be formed without bonding Al crystal grains, and light transmittance can be improved. it can. However, depending on the film formation method, there are cases where it becomes a columnar film and an amorphous film, and the columnar film of the first embodiment has a higher transmittance and is particularly effective for improving the efficiency of the device. This is a preferred embodiment.

(Third embodiment)
In the present embodiment, a case where the organic EL element of the present invention is applied to an organic EL element having a top emission structure will be described as an example. FIG. 7 is a diagram illustrating an example of the configuration of the organic EL element according to the third embodiment.

  As shown in FIG. 7, the organic EL element 101 according to the third embodiment includes an anode 103, a reflective layer 104, an organic layer 105, and a cathode 106 on a substrate 102. The configurations of the substrate 102, the anode 103, and the organic layer 105 are the same as the configurations of the substrate 2, the anode 3, and the first organic layer 4 in the first embodiment.

  The reflective layer 104 is a layer having a function of reflecting light from the organic layer 105 toward the organic layer 105 side. The reflective layer 104 is provided between the anode 103 and the organic layer 105. Note that the reflective layer 104 may be provided between the substrate 102 and the anode 103. Examples of the material used for the reflective layer 104 include materials selected from the group consisting of Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, and compounds thereof having good light reflectivity. Can be mentioned.

  The cathode 106 includes at least one metal film. In this embodiment, the cathode 106 includes a layer 107 containing an alkali metal or an alkaline earth metal, a metal film 108, and a conductive layer 109. The configuration of the layer 107 containing an alkali metal or alkaline earth metal is the same as the configuration of the layer 51 containing an alkali metal or alkaline earth metal of the first embodiment. The metal film 108 has the same configuration as that of the metal film 52 of the first embodiment or the second embodiment. That is, the metal film 108 is a discontinuous film containing a metal in which particles grow in a columnar shape, or an amorphous metal film.

  The conductive layer 109 is a layer that functions as a protective electrode for the metal film 108 and a conductive electrode in the surface direction. As a material used for the conductive layer 109, a metal thin film, a conductive film such as indium tin oxide (ITO) or indium zinc oxide (IZO) having high transmittance and conductivity can be given.

  According to the organic EL element 101 configured as described above, the light from the organic layer 105 is transmitted through the cathode 106 and emitted to the outside, and the light from the organic layer 105 is reflected by the reflective layer 104, so that the organic layer 105 and the cathode 106 are transmitted to the outside. In the present embodiment, the metal film 108 of the cathode 106 is a discontinuous film containing a metal in which particles grow in a columnar shape, or an amorphous metal, as in the configuration of the metal film 52 of the first or second embodiment. Since it is a film, even if the metal film 109 has a thickness that functions as an electrode, the light transmittance does not decrease. For this reason, the luminous efficiency of the organic EL element 101 can be improved. In addition, an increase in driving voltage of the organic EL element 101 can be suppressed.

(Fourth embodiment)
In the present embodiment, a case where the organic EL element of the present invention is applied to an organic EL element having a see-through structure will be described as an example. FIG. 8 is a diagram illustrating an example of the configuration of the organic EL element according to the fourth embodiment.

  As illustrated in FIG. 8, the organic EL element 201 according to the fourth embodiment includes an anode 203, an organic layer 204, and a cathode 205 on a substrate 202. Note that the configurations of the substrate 202, the organic layer 204, and the cathode 205 are the same as the configurations of the substrate 102, the organic layer 105, and the cathode 106 of the third embodiment. That is, the metal film of the cathode 205 is a discontinuous film containing a metal in which particles grow in a columnar shape or an amorphous metal film. The configuration of the anode 203 is the same as the configuration of the anode 3 of the first embodiment.

  According to the organic EL element 201 configured as described above, light from the organic layer 204 is transmitted to the outside through the cathode 205, and light from the organic layer 204 is transmitted through the anode 203 and the substrate 202. And released to the outside. In the present embodiment, the metal film of the cathode 205 is a discontinuous film containing a metal in which particles grow in a columnar shape or an amorphous metal film, similarly to the configuration of the metal film 52 of the first or second embodiment. Therefore, even if this metal film is made to have a film thickness that functions as an electrode, the light transmittance does not decrease. For this reason, the luminous efficiency of the organic EL element 201 can be improved. In addition, an increase in driving voltage of the organic EL element 201 can be suppressed.

In the third and fourth embodiments, a layer containing a compound containing alkali metal ions or alkaline earth metal ions is used instead of the layer containing alkali metal or alkaline earth metal of the cathodes 106 and 205. It may be formed. Also in this case, the same effect as the layer containing an alkali metal or an alkaline earth metal can be obtained. The cathode of the device as in the third and fourth embodiments is required to have three functions of high conductivity, high electron injection property, and high light transmittance at the same time. As the light-transmitting conductive film, an ITO oxide transparent conductive material or a metal thin film such as silver with relatively little light absorption may be used. However, since these conductive layers alone cannot provide electron injection properties, It is preferable to use the metal film of the invention by inserting it between an organic layer and a conductive layer. The metal film of the present invention is a film having both the function of reducing alkali metal ions and alkali metal ions and the function of self-organization of columnar particles or amorphous films, so that stable high electron injection and high light transmittance are achieved. Thus, an element capable of being driven with high efficiency and low voltage can be obtained.
Also in the third and fourth embodiments, when a mixed film containing aluminum and indium is used for the metal film 52 as in the first embodiment, the mixing ratio of aluminum and indium is: The weight ratio is preferably 88:12 to 35:65, and the reason is the same as that of the first embodiment.

  Hereinafter, specific examples of the present invention will be shown together with comparative examples, and the present invention will be described in more detail.

(Examples 1-15, Comparative Examples 1-11)
An ITO transparent electrode thin film (anode) was formed to a thickness of 100 nm on a glass substrate by RF sputtering and patterned. This glass substrate with an ITO transparent electrode was subjected to ultrasonic cleaning using a neutral detergent, acetone and ethanol, and then pulled up from boiling ethanol and dried. After the surface of the transparent electrode is washed with UV / O ₃ , the film is formed by the resistance heating vacuum deposition method in the structure of the first organic layer / the layer containing alkali metal / metal film / electron accepting layer / second organic layer / cathode. The organic EL element having a tandem structure was prepared.

  The first organic layer is a hole injection material 1 (100 nm) / hole transport material 1 (10 nm) / host material 1 + a light emitting dopant 1 (20 nm, volume ratio 97: 4), and a layer containing an alkali metal is (Alq 3 + Li (4 nm) , Volume ratio 95: 5)), the metal film is an Al + In alloy (film thickness = 1-25 nm (Al: In = 88: 12-35: 65)), the electron-accepting layer is the electron-accepting material 1 (4 nm), the second The organic layer of hole transport material 1 (10 nm) / host material 1 + hole transport material 1 (20 nm, volume ratio 85:15) / host material 1 (20 nm) / Alq3 (10 nm), and the cathode is (LiF (0.5 nm)) / Al (100 nm)). The distance from the metal film to the cathode is 64 nm.

  In Examples 1-4, 14, and 15, the mixing ratio of Al and In of the metal film was changed, and in Examples 5 to 13, the thickness of the metal film was changed at the mixing ratio of Example 2. In Comparative Examples 1 to 11, the metal used for the metal film, the mixing ratio, and the film thickness were changed.

The element characteristics were evaluated by spectroscopic analysis at 580 nm (emission from the first organic layer) and 470 nm (emission from the second organic layer) under the driving conditions of a current density of 500 mA / cm ² , 100 Hz, Duty = 1/120. Radiance and driving voltage were measured. Further, the reflectance from the light emitting surface side of the element was measured as an index of light transmittance of the metal film. Regarding the reflectivity, an organic EL element without a metal film was separately prepared, and evaluation was performed with a relative reflectivity when the reflectivity of this element was 100%. The results are shown in Table 2.

  As shown in Table 2, it was confirmed that by using an Al + In alloy as the metal film, an organic EL element capable of improving luminous efficiency and suppressing an increase in driving voltage can be formed. Furthermore, when the In mixing ratio is low, the light transmittance is low and the light emission is weak, and when the In mixing ratio is high, the carrier injection property is low and the driving voltage is high, so the mixing ratio of Al and In is the weight ratio. 88: 12-53: 47 was confirmed to be more preferable. Further, since the relative reflectance of the element increases as the In mixing ratio increases, it can be seen that the improvement in the emission intensity is due to the improvement in the light transmittance of the metal film.

  Further, from the results of Examples 5 to 13, the film thickness of the mixed film of Al and In is preferably about 2 to 10 nm, and particularly within this range, both strong emission intensity and low driving voltage are compatible. It could be confirmed. On the other hand, the Al single composition films of Comparative Examples 1 to 5 are the same as the Al + In alloy in that the carrier injection property is improved and the driving voltage is lowered as the film thickness is increased. As a result, a rapid decrease in light transmittance occurs and the efficiency is lowered. For this reason, in the case of the Al single composition film, it was confirmed that even if the film thickness was adjusted, it was impossible to achieve both strong emission intensity and low driving voltage. Moreover, it was confirmed that even when the metal film was made of Li, Al + Li, Ag, Al + Ag as in Comparative Examples 6 to 11, it was impossible to achieve both strong emission intensity and low driving voltage.

The structures of the metal films of Example 1 and Comparative Example 1 are illustrated. FIG. 9 shows the structure of the metal film of Example 1, and FIG. 10 shows the structure of the metal film of Comparative Example 1.
As shown in FIG. 9, in the metal film of Example 1, it was confirmed that the metal crystals were arranged in an island shape (columnar growth film) even when the film thickness was 4 nm. On the other hand, as shown in FIG. 10B, in the metal film of Comparative Example 3, since the islands of metal crystals grow and the particles grow so as to be bonded to each other in the film surface direction, the number of pores is reduced. It was confirmed that the film was a continuous film. As described above, in the metal film of Example 1, since the particles grow in a columnar shape, it is confirmed that the light transmission does not decrease, and the light emission outside the dots due to the decrease in the insulation in the film surface direction of the metal electrode film does not occur. did it. Such a structure can be confirmed by a TEM image and a STEM image of a transmission electron microscope.

(Examples 16-24, Comparative Examples 12-18)
An organic EL device was prepared and evaluated in the same manner except that Alq + LiF (4 nm, volume ratio 94: 6) was formed as a layer containing an alkali metal ion-containing substance instead of the layer containing an alkali metal. The results are shown in Table 3.

  As shown in Table 3, the layer containing an alkali metal ion-containing material is replaced with an alkali metal ion-containing layer, and the metal film is made of an Al + In alloy to improve luminous efficiency and suppress an increase in driving voltage. It was confirmed that an organic EL element capable of forming a film could be formed. This indicates that the Al + In alloy film has a function of reducing alkali or alkaline earth metal ions in the same manner as Al.

(Examples 25 and 26, Comparative Examples 19 to 20)
The first light emitting layer is a hole injection material 1 (96 nm) / hole transport material 2 (10 nm) / host material 2 + dopant 1 (20 nm, volume ratio 96: 4) / host material 2 (74 nm), and a second organic layer And Example 1 except that hole transport material 2 (61 nm) / host material 3 + hole transport material 2 + dopant material 2 (30 nm, volume ratio 85: 15: 3) / host material 3 (10 nm) / Alq3 (4 nm) Similarly, an organic EL element was produced. With this configuration, the distance from the metal film to the cathode, which is the sum of the film thicknesses of the electron accepting layer and the second organic layer, was set to 109 nm, and the same evaluation as in Example 1 was performed. The results are shown in Table 4.

  As shown in Table 4, even if the distance from the metal film to the cathode is changed, the metal film is made of an Al + In alloy, so that the luminous efficiency is improved, the increase in driving voltage is suppressed, and the color depending on the viewing angle It was confirmed that an organic EL element capable of suppressing the change in degree could be formed.

(Examples 27-41, Comparative Examples 21-24)
An ITO transparent electrode thin film (anode) was formed to a thickness of 100 nm on a glass substrate by RF sputtering and patterned. This glass substrate with an ITO transparent electrode was subjected to ultrasonic cleaning using a neutral detergent, acetone and ethanol, and then pulled up from boiling ethanol and dried. After the surface of the transparent electrode is cleaned with UV / O ₃ , the reflective electrode (Ag 100 nm) / the first organic layer / the layer containing Li / the metal film (Al + In alloy) / the conductive layer (Ag 8 nm) / Ar is formed by resistance heating vacuum deposition. Film formation was performed with a film (organic layer) configuration, and an organic EL element having a top emission structure was produced. Except that the first organic layer is hole injection material 1 (55 nm) / hole transport material 1 (10 nm) / host material 4 + light emitting dopant 1 (20 nm, volume ratio 97: 4), and the Ar film is hole transport material 1 described above. In the same manner as above, element characteristics were evaluated when the metal type, mixing ratio, and film thickness of the metal film were changed. The results are shown in Table 5.

  As shown in Table 5, for the organic EL element having a top emission structure, there is an organic EL element that can improve luminous efficiency and suppress an increase in driving voltage by using an Al + In alloy as a cathode metal film. It was confirmed that it could be formed. Furthermore, it was confirmed that the light emission efficiency was further improved and the increase in driving voltage could be further suppressed by setting the mixing ratio of Al and In to 88:12 to 53:47 by weight.

(Examples 42 to 48, Comparative Example 25)
An organic EL device having a top emission structure was prepared in the same manner except that a layer containing LiF was used instead of the layer containing Li, and device characteristics were evaluated. The results are shown in Table 6.

  As shown in Table 6, an organic EL element capable of improving luminous efficiency and suppressing an increase in driving voltage by using a metal film made of an Al + In alloy even when a layer containing LiF is used instead of a layer containing Li. It was confirmed that can be formed.

(Examples 49 to 63, Comparative Examples 26 to 29)
An ITO transparent electrode thin film (anode) was formed to a thickness of 100 nm on a glass substrate by RF sputtering and patterned. This glass substrate with an ITO transparent electrode was subjected to ultrasonic cleaning using a neutral detergent, acetone and ethanol, and then pulled up from boiling ethanol and dried. After the surface of the transparent electrode is washed with UV / O ₃ , the first organic layer / the layer containing Li / the metal film (Al + In alloy) / the conductive layer (Ag 8 nm) / the Ar film (organic layer) is formed by resistance heating vacuum deposition. Film formation was performed with the configuration, and an organic EL element having a see-through structure was produced. The first organic layer is the same as that described above except that the hole injection material 1 (55 nm) / the hole transport material 1 (10 nm) / the host material 5 + the light emitting dopant 1 (20 nm, volume ratio 97: 4) and the Ar film are the hole transport material 1. In the same manner as above, element characteristics were evaluated when the metal type, mixing ratio, and film thickness of the metal film were changed. The results are shown in Table 7.

  As shown in Table 7, for an organic EL element having a see-through structure, by using an Al + In alloy as a cathode metal film, an organic EL element capable of improving luminous efficiency and suppressing an increase in driving voltage can be formed. Was confirmed. Furthermore, it was confirmed that the light emission efficiency was further improved and the increase in driving voltage could be further suppressed by setting the mixing ratio of Al and In to 88:12 to 53:47 by weight.

(Examples 64-70 and Comparative Example 30)
An organic EL element having a see-through structure was prepared in the same manner except that a layer containing LiF was used instead of the layer containing Li, and element characteristics were evaluated. The results are shown in Table 8.

  As shown in Table 8, even when a layer containing LiF is used instead of a layer containing Li, by using an Al + In alloy as the metal film, the light emitting efficiency can be improved and an increase in driving voltage can be suppressed. It was confirmed that can be formed.

(Examples 71-85, Comparative Examples 31-35)
Organic EL elements were prepared in the same manner as in Examples 1 to 15 and Comparative Examples 1 to 11 except that the metal film was formed by sputtering to form an amorphous metal film. The results are shown in Table 9. The composition ratio of Al and In was changed by using a pure Al target and a mixed target of Al: In = 77: 23, and further placing an In piece on the target.

  As shown in Table 9, it can be confirmed that even when a metal film is formed by a sputtering method to form an amorphous metal film, an organic EL element capable of improving luminous efficiency and suppressing an increase in drive voltage can be formed. It was. It was also confirmed that the light emission efficiency was further improved and the drive voltage could be further suppressed by setting the mixing ratio of Al and In to 88:12 to 53:47 by weight. Furthermore, the film thickness of the mixed film of Al and In is preferably about 2 to 10 nm, and in this range, it was confirmed that particularly strong emission intensity and low driving voltage are compatible.

  Here, the structure of the metal film of Example 71 is illustrated. FIG. 11 shows the structure of the metal film of Example 71. As shown in FIG. 11, in the metal film of Example 71, even when the film thickness is increased, most of Al in the film is deposited while maintaining the microcrystals, so that there are fine voids between the microcrystals. It exists and light is transmitted through the gap. Note that In in the film exists as crystal grains. For this reason, even if the film thickness increases, the light transmittance does not decrease.

(Examples 86 to 94, Comparative Examples 36 to 38)
Except that Alq + LiF (4 nm, volume ratio 94: 6) was formed as a layer containing an alkali metal ion-containing material instead of the layer containing alkali metal, the same as in Examples 71-85 and Comparative Examples 31-35 An organic EL element including an amorphous metal film was prepared and evaluated. The results are shown in Table 10.

  As shown in Table 10, in place of a layer containing an alkali metal, an organic layer containing an amorphous metal film that can improve luminous efficiency and suppress an increase in driving voltage, even as a layer containing an alkali metal ion-containing material. It was confirmed that an EL element could be formed.

(Examples 95 to 109, Comparative Examples 39 to 42)
Organic EL elements having a top emission structure were prepared in the same manner as in Examples 27 to 41 and Comparative Examples 21 to 24 except that the metal film was formed by sputtering to form an amorphous metal film. The results are shown in Table 11. The composition ratio of Al and In was changed by using a pure Al target and a mixed target of Al: In = 77: 23, and further placing an In piece on the target.

  As shown in Table 11, for the organic EL element having a top emission structure, by using an amorphous metal film as the cathode metal film, the emission efficiency can be improved and an increase in drive voltage can be suppressed. It was confirmed that an EL element could be formed.

(Examples 110 to 116, Comparative Example 43)
Except that Alq + LiF (4 nm, volume ratio 94: 6) was formed as a layer containing an alkali metal ion-containing substance instead of the layer containing an alkali metal, the same as in Examples 95 to 109 and Comparative Examples 39 to 42 An organic EL element including an amorphous metal film having a top emission structure was prepared and evaluated. The results are shown in Table 12.

  As shown in Table 12, in place of the layer containing an alkali metal, the layer containing the alkali metal ion-containing material can improve the light emission efficiency and suppress the increase in driving voltage. It was confirmed that an organic EL element including a metal film can be formed.

(Examples 117 to 131, Comparative Examples 44 to 47)
A see-through structure organic EL device was prepared in the same manner as in Examples 49 to 63 and Comparative Examples 26 to 29 except that the metal film was formed by sputtering to form an amorphous metal film. The results are shown in Table 13. The composition ratio of Al and In was changed by using a pure Al target and a mixed target of Al: In = 77: 23, and further placing an In piece on the target.

  As shown in Table 13, for an organic EL element having a see-through structure, the cathode metal film is made of an amorphous metal film, thereby improving the light emission efficiency and suppressing an increase in driving voltage. It was confirmed that can be formed.

(Examples 132 to 138, Comparative Example 48)
Except that Alq + LiF (4 nm, volume ratio 94: 6) was formed as a layer containing an alkali metal ion-containing material instead of the layer containing an alkali metal, the same as in Examples 117 to 131 and Comparative Examples 44 to 47 An organic EL element including an amorphous metal film having a see-through structure was prepared and evaluated. The results are shown in Table 14.

  As shown in Table 14, an amorphous metal film having a see-through structure capable of improving the light emission efficiency and suppressing an increase in driving voltage even when the layer containing an alkali metal ion-containing substance is used instead of the layer containing an alkali metal. It has been confirmed that an organic EL device containing can be formed.

(In addition amount and transmittance of Al + In film)
A columnar film according to the first embodiment and an amorphous film according to the second embodiment are formed on glass to have a thickness of 10 nm and sealed with a glass cap without being exposed to the atmosphere. Sex was measured. The columnar film of the first embodiment is formed by forming an Al + In film by resistance heating vapor deposition (evaporation), and the second implementation is performed by forming an Al + In film by sputtering. An amorphous film of the form is formed. The results are shown in FIG. As shown in FIG. 12, it was confirmed that the transmittance was improved in both the columnar film of the first embodiment and the amorphous film of the second embodiment.

  The present invention is useful for an organic EL device.

DESCRIPTION OF SYMBOLS 1 Organic EL element 2 Board | substrate 3 Anode 4 1st organic layer 5 Intermediate electrode 6 2nd organic layer 7 Cathode 41, 61 Hole injection transport layer 42, 62 Light emitting layer 43, 63 Electron injection transport layer 51 Alkali metal or alkali Layer 52 containing earth metal Metal film 53 Electron accepting layer

Claims (11)

Laminating at least an anode, a first organic layer having a light emitting function, an intermediate electrode, a second organic layer having a light emitting function, and a cathode on a substrate;
The intermediate electrode includes at least one metal film,
The organic EL element, wherein the metal film is a discontinuous film containing a metal in which particles grow in a columnar shape. Laminating at least an anode, a first organic layer having a light emitting function, an intermediate electrode, a second organic layer having a light emitting function, and a cathode on a substrate;
The intermediate electrode includes at least one metal film,
The metal film is a film containing an amorphous metal composed of two or more kinds of metal elements, and at least one kind of metal element is present without forming a solid solution with other metal elements. Organic EL element. Laminating at least an anode, a first organic layer having a light emitting function, an intermediate electrode, a second organic layer having a light emitting function, and a cathode on a substrate;
The intermediate electrode includes at least one metal film,
The organic EL element, wherein the metal film contains at least aluminum and indium.   4. The distance from the cathode to the intermediate electrode is λ / 2n (λ is a light emission wavelength, and n is a refractive index between the cathode and the intermediate electrode). 5. The organic EL element of description. At least an anode, an organic layer having a light emitting function, and a cathode are sequentially laminated on the substrate,
The cathode includes at least one metal layer;
The organic EL element, wherein the metal film is a discontinuous film containing a metal in which particles grow in a columnar shape. At least an anode, an organic layer having a light emitting function, and a cathode are sequentially laminated on the substrate,
The cathode includes at least one metal layer;
The metal film is a film containing an amorphous metal composed of two or more metal elements, and at least one metal element is present without forming a solid solution with other metal elements. Organic EL element. At least an anode, an organic layer having a light emitting function, and a cathode are sequentially laminated on the substrate,
The cathode includes at least one metal layer;
The organic EL element, wherein the metal film contains at least aluminum and indium.   8. The organic EL element according to claim 3, wherein a mixing ratio of the aluminum and indium is 88:12 to 35:65 by weight ratio. 9.   8. The organic EL element according to claim 3, wherein a mixing ratio of the aluminum and indium is 88:12 to 53:47 by weight ratio. 9.   10. The organic EL element according to claim 1, wherein the layer in contact with the anode side of the metal film contains an alkali metal or an alkaline earth metal. 11.   10. The organic EL device according to claim 1, wherein the layer in contact with the anode side of the metal film contains a compound containing an alkali metal ion or an alkaline earth metal ion.