JP2008258198A - Light-emitting element, light-emitting device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting element excellent in luminescence characteristics in which diffusion of metal ions from other functional layer such as an electron injection layer to a light-emitting layer is prevented, and to provide a highly reliable light-emitting device equipped with this light-emitting element and an electronic apparatus. <P>SOLUTION: The light-emitting element 1 comprises an anode 3, a cathode 8, and a laminate 15 of a hole transport layer 4, a light-emitting layer (organic light-emitting layer) 5, an intermediate layer 6 and an electron injection layer 7 formed between the anode 3 and the cathode 8 sequentially from the anode 3 side. The intermediate layer 6 principally comprising an ion capturing substance 61 capable of capturing metal ions, and an organic compound 62 where the number of unshared electron pairs having a function for transporting electrons is 1 or less. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light emitting element, a light emitting device, and an electronic apparatus.

The organic electroluminescence (EL) element in which the light emitting organic layer (organic electroluminescence layer) is provided between the cathode and the anode can greatly reduce the applied voltage compared to the inorganic EL element, and has a wide variety. A light emitting element can be manufactured.
Currently, in order to obtain a higher performance organic EL element, a device structure in which various layers are provided between a cathode and a light emitting organic layer (light emitting layer) or between an anode and a light emitting layer has been proposed. There is active research.

  Examples of such a layer include an electron transport layer provided between the cathode and the light-emitting layer, and an electron injection layer provided between the electron transport layer and the cathode. Of these, alkali metal compounds and alkaline earth metal compounds are often used as the constituent material of the electron injection layer. Among these, alkali metal compounds have a very small work function, and it is known that an organic EL element can obtain high luminance by constituting an electron injection layer (see, for example, Patent Document 1).

However, when the electron injection layer is composed of an alkali metal compound, alkali metal ions are released from the electron injection layer and diffused to the light emitting layer through the electron transport layer. As a result, there is a problem that the light emission characteristics deteriorate.
In addition, for example, in a functional layer containing an organic compound such as an electron transport layer, alkali metal ions are mixed due to a catalyst or a solvent used when the organic compound (electron transport material) is synthesized. End up. Alkali metal ions mixed in this material diffuse into the light emitting layer.
Furthermore, for example, when the cathode is made of a conductive material containing a metal such as Ag, metal ions are generated by ionization of the metal contained in the cathode, and the metal ions pass through the electron injection layer and the electron transport layer. Diffuses into the light emitting layer.
In these cases as well, it is a cause of deteriorating the light emission characteristics of the organic EL element.

For the purpose of preventing such diffusion of alkali metal ions or metal ions from the cathode, for example, a crown ether derivative capable of capturing alkali metal ions or metal ions from the cathode is provided between the cathode and the light emitting layer. Providing a metal ion trap layer to be contained has been proposed (for example, see Patent Document 2).
However, even when such a metal ion trap layer is provided, diffusion of alkali metal ions or metal ions from the cathode to the light emitting layer has not been sufficiently prevented.

JP-A-9-17574 JP 2005-38819 A

  An object of the present invention is to prevent a metal ion from diffusing into a light-emitting layer from another functional layer such as an electron injection layer, and to have a light-emitting element having excellent light-emitting characteristics, and a reliable light-emitting device including the light-emitting element It is to provide an apparatus and an electronic device.

Such an object is achieved by the present invention described below.
A light emitting device according to the present invention comprises an anode,
A cathode,
An organic light emitting layer provided between the anode and the cathode;
An intermediate layer provided between the cathode and the organic light emitting layer;
The intermediate layer includes an ion trapping substance capable of trapping metal ions and an organic compound having a number of unshared electron pairs having a function of transporting electrons of 1 or less.
This reliably prevents metal ions from being transferred between the organic compound and the ion trapping substance, so that the metal ions can be reliably trapped by the ion trapping substance in the intermediate layer. As a result, diffusion of metal ions from the intermediate layer to the light emitting layer is prevented, and a light emitting element having excellent light emission characteristics can be obtained.

In the light emitting device of the present invention, the intermediate layer is preferably formed by dispersing the ion trapping substance in the organic compound.
Thereby, while being able to capture | recover a metal ion, since an organic compound intervenes between adjacent ion capture | acquisition parts, delivery of the metal ion between these ion capture | acquisition substances can be prevented.

In the light emitting device of the present invention, the content of the ion trapping substance in the intermediate layer is preferably 1 to 40 wt%.
By setting it within this range, the function as an electron transport layer for transporting electrons to the intermediate layer is exhibited, and the transfer of metal ions between adjacent ion trapping substances is reliably prevented. As a result, metal ions can be more reliably trapped by the ion trapping substance. As a result, diffusion of metal ions from the intermediate layer to the light emitting layer can be more reliably prevented.
In the light emitting device of the present invention, the average thickness of the intermediate layer is preferably 20 to 100 nm.
Accordingly, diffusion of metal ions from other functional layers to the light emitting layer can be reliably prevented, and the function of the intermediate layer as the electron transport layer can be reliably exhibited.

A light emitting device according to the present invention comprises an anode,
A cathode,
An organic light emitting layer provided between the anode and the cathode;
An intermediate layer provided between the cathode and the organic light emitting layer;
The intermediate layer includes an ion trapping material capable of trapping metal ions and an insulating polymer,
The insulating polymer includes a monomer component having an unshared electron pair of 1 or less.
This reliably prevents metal ions from being transferred between the insulating polymer and the ion trapping substance, so that the metal ions can be reliably trapped by the ion trapping substance in the intermediate layer. As a result, diffusion of metal ions from the intermediate layer to the light emitting layer is prevented, and a light emitting element having excellent light emission characteristics can be obtained.

In the light emitting device of the present invention, it is preferable that the intermediate layer is formed by dispersing the ion trapping substance in the insulating polymer.
Thereby, while being able to capture | recover a metal ion, since an insulating polymer intervenes between adjacent ion trapping parts, delivery of the metal ion between these ion trapping substances can be prevented.

In the light emitting device of the present invention, the content of the ion trapping substance in the intermediate layer is preferably 1 to 40 wt%.
By setting within such a range, it is possible to reliably prevent the transfer of metal ions between adjacent ion trapping substances, so that the metal ions can be trapped more reliably by the ion trapping substance. . As a result, diffusion of metal ions from the intermediate layer to the light emitting layer can be reliably prevented.

In the light emitting device of the present invention, the average thickness of the intermediate layer is preferably 5 to 10 nm.
By setting within this range, electrons transported from the cathode side can be supplied to the light emitting layer through the intermediate layer by the tunnel effect, and sufficient ion trapping ability can be imparted to the intermediate layer.

In the light emitting device of the present invention, it is preferable that the ion trapping substance is capable of trapping alkali metal ions contained in the intermediate layer.
As a result, alkali metal ions mixed as impurities in the intermediate layer can be reliably trapped by the ion trapping substance, and diffusion of the alkali metal ions to the light emitting layer can be reliably prevented.

In the light emitting device of the present invention, the cathode contains a metal element,
It is preferable that the ion trapping substance is capable of trapping metal ions derived from the metal element.
Thereby, the metal ion derived from the cathode diffused in the intermediate layer can be reliably captured by the ion trapping substance, and the diffusion of the metal ion to the light emitting layer can be surely prevented.

In the light emitting device of the present invention, an electron injection layer containing an alkali metal compound is provided between the cathode and the intermediate layer,
It is preferable that the ion trapping substance is capable of trapping alkali metal ions derived from the alkali metal compound.
Thereby, the alkali metal ion derived from the electron injection layer diffused in the intermediate layer can be reliably trapped by the ion trapping substance, and the diffusion of the alkali metal ion to the light emitting layer can be surely prevented.

In the light emitting device of the present invention, it is preferable that the ion trapping substance has a ring structure, and the type and size of the ring structure are selected according to the type of metal ion and / or the difference in ion diameter.
Thus, the metal ion to be captured can be reliably captured by adopting a configuration in which the type of ring and the size of the ring are selected according to the type and / or ion diameter of the metal ion.

In the light emitting device of the present invention, the cyclic structure preferably contains at least one of an oxygen atom, a nitrogen atom, a sulfur atom and a phosphorus atom.
Such a cyclic structure is preferable because it has a very high ion trapping ability. Further, there is an advantage that the size of the ring (inner space) and the flexibility of the ring can be easily adjusted, and the synthesis of such a cyclic structure can be performed relatively easily.

In the light emitting device of the present invention, it is preferable that the cyclic structure has 6 or more carbon atoms and 2 or more at least one hetero atom in the ring.
Such a cyclic structure is preferable because it has a very high ion trapping ability. Further, there is an advantage that the size of the ring (inner space) and the flexibility of the ring can be easily adjusted, and the synthesis of such a cyclic structure can be performed relatively easily.

A light emitting device according to the present invention includes the light emitting element of the present invention.
Thereby, a highly reliable light-emitting device can be obtained.
An electronic apparatus according to the present invention includes the light emitting device of the present invention.
As a result, a highly reliable electronic device can be obtained.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a light-emitting element, a light-emitting device, and an electronic device according to the invention will be described with reference to the accompanying drawings.
<Light emitting element>
<< First Embodiment >>
First, a first embodiment of the light emitting device of the present invention will be described.
FIG. 1 is a diagram schematically showing a longitudinal section of a first embodiment of a light emitting device of the present invention. In the following description, for convenience of explanation, the upper side in FIG. 1 will be described as “upper” and the lower side as “lower”.

  A light-emitting element (organic electroluminescent element) 1 shown in FIG. 1 includes a positive hole transport layer in order from the anode 3 side between an anode 3 provided on a substrate 2, a cathode 8, and the anode 3 and the cathode 8. 4, a light emitting layer 5, an intermediate layer 6, and an electron injecting layer 7, and a laminate 15, the whole of which is sealed with a sealing member 9 through a sealing material 10 to emit light. This is a top emission type light emitting element that extracts light emitted from the layer 5 from the sealing member 9 side.

The substrate 2 serves as a support of the light emitting element 1 (hereinafter simply referred to as “light emitting element 1”). Since the light emitting element 1 of the present embodiment is configured to extract light from the sealing member 9 side (top emission type), the substrate 2 and the anode 3 are not required to have translucency, respectively.
Examples of the constituent material of the substrate 2 include ceramic materials such as alumina, resin materials such as polyethylene terephthalate and polymethyl methacrylate, and glass materials such as quartz glass and soda glass. One or two or more of them can be used in combination.

Moreover, although the average thickness of the board | substrate 2 is not specifically limited, It is preferable that it is about 0.1-30 mm, and it is more preferable that it is about 0.1-10 mm.
In the case where the light emitting element 1 is configured to extract light from the substrate 2 side (bottom emission type), the substrate 2 is substantially transparent (colorless transparent, colored transparent or translucent) among those described above. Is selected.

The anode 3 is an electrode that injects holes into the hole transport layer 4 described later. As a constituent material of the anode 3, it is preferable to use a material having a large work function and excellent conductivity.
Examples of the constituent material of the anode 3 include ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), In ₃ O ₃ , Au, Cu, and alloys containing these, and one or two of them are used. A combination of more than one species can be used.
The average thickness of the anode 3 is not particularly limited, but is preferably about 10 to 200 nm, and more preferably about 50 to 150 nm.

On the other hand, the cathode 8 is an electrode for injecting electrons into an electron injection layer 7 described later. As a constituent material of the cathode 8, a material having a small work function is preferably used.
Examples of the constituent material of the cathode 8 include metals such as Mg, Ca, Sr, La, Ce, Er, Eu, Sc, Y, Yb, Ag, Cu, and Al, or alloys containing them. Among them, one kind or a combination of two or more kinds (for example, a multi-layer laminate) can be used.

In particular, when an alloy is used as the constituent material of the cathode 8, it is preferable to use an alloy containing a stable metal element such as Ag or Al, specifically an alloy such as MgAg or MgAl. By using such an alloy as a constituent material of the cathode 8, the electron injection efficiency and stability of the cathode 8 can be improved.
The average thickness of the cathode 8 is not particularly limited, but is preferably about 100 to 10,000 nm, and more preferably about 200 to 500 nm.
As in the present embodiment, in the case of the top emission type, the cathode 8 is made of a material having a small work function or an alloy containing these materials with a thickness of about 5 to 20 nm, and has transparency, and further has an upper surface such as ITO. It is preferable that the conductive material is formed of a laminated body having a thickness of about 100 to 500 nm.

On the anode 3, a hole transport layer 4 is provided in the present embodiment. The hole transport layer 4 has a function of transporting holes injected from the anode 3 to the light emitting layer 5.
Examples of the constituent material of the hole transport layer 4 include polyarylamine, fluorene-arylamine copolymer, fluorene-bithiophene copolymer, poly (N-vinylcarbazole), polyvinylpyrene, polyvinylanthracene, polythiophene, and polyalkyl. Examples include thiophene, polyhexylthiophene, poly (p-phenylene vinylene), polytinylene vinylene, pyrene formaldehyde resin, ethyl carbazole formaldehyde resin or derivatives thereof, and use one or a combination of two or more of these. Can do.

Moreover, the said compound can also be used as a mixture with another compound. As an example, the polythiophene-containing mixture includes poly (3,4-ethylenedioxythiophene / styrene sulfonic acid) (PEDOT / PSS).
The average thickness of the hole transport layer 4 is not particularly limited, but is preferably about 10 to 150 nm, and more preferably about 50 to 100 nm.
This hole transport layer 4 is omitted when the combination of constituent materials contained in the anode 3 and the light emitting layer 5 is such that holes are smoothly injected from the anode 3 to the light emitting layer 5. You can also

  A light emitting layer (organic light emitting layer) 5 is provided on the hole transport layer 4. Electrons are supplied (injected) to the light emitting layer 5 from an intermediate layer 6 described later, and holes are supplied from the hole transport layer 4. In the light emitting layer 5, holes and electrons are recombined, and excitons (excitons) are generated by the energy released during the recombination. When the excitons return to the ground state, energy (fluorescence or phosphorescence) is generated. ) Is emitted (emitted).

As the constituent material of the light emitting layer 5, 1,3,5-tris [(3-phenyl-6-tri-fluoromethyl) quinoxalin-2-yl] benzene (TPQ1), 1,3,5-tris [{3 Benzene compounds such as-(4-t-butylphenyl) -6-trisfluoromethyl} quinoxalin-2-yl] benzene (TPQ2), metals such as phthalocyanine, copper phthalocyanine (CuPc), iron phthalocyanine or metal free Phthalocyanine compounds, tris (8-quinolinolato) aluminum (Alq ₃ ), low molecular weight compounds such as factory (2-phenylpyridine) iridium (Ir (ppy) ₃ ), oxadiazole polymers, Triazole polymer, carbazole polymer such as poly (9-vinylcarbazole) (PVK), poly Examples thereof include polymers such as fluorene polymers and polyparaphenylene vinylene polymers, and these can be used alone or in combination.
Although the average thickness of such a light emitting layer 5 is not specifically limited, It is preferable that it is about 10-150 nm, and it is more preferable that it is about 50-100 nm.

An intermediate layer 6 is provided on the light emitting layer 5.
In this invention, it has the characteristics in the structure (especially constituent material) of this intermediate | middle layer 6. FIG. This point (characteristic) will be described in detail later.
On the intermediate layer 6, an electron injection layer 7 having a function of improving the electron injection efficiency from the cathode 8 is provided.

Examples of the constituent material (electron injection material) of the electron injection layer 7 include various inorganic insulating materials and various inorganic semiconductor materials. By configuring the electron injection layer 7 with such a constituent material, current leakage can be effectively prevented, and the electron injection property can be improved and the durability can be improved.
Examples of such inorganic insulating materials include alkali metal chalcogenides (oxides, sulfides, selenides, tellurides), alkaline earth metal chalcogenides, alkali metal halides, and alkaline earth metal halides. Of these, one or two or more of these can be used in combination. By forming the electron injection layer using these as main materials, the electron injection property can be further improved. In particular, an alkali metal compound (alkali metal chalcogenide, alkali metal halide, etc.) has a very small work function, and the light-emitting element 1 can be obtained with high luminance by forming the electron injection layer 7 using the work function. Become.

Examples of the alkali metal chalcogenide include Li ₂ O, LiO, Na ₂ S, Na ₂ Se, and NaO.
Examples of the alkaline earth metal chalcogenide include CaO, BaO, SrO, BeO, BaS, MgO, and CaSe.

Examples of the alkali metal halide include CsF, LiF, NaF, KF, LiCl, KCl, and NaCl.
Examples of the alkaline earth metal halide include CaF ₂ , BaF ₂ , SrF ₂ , MgF ₂ , and BeF ₂ .
In addition, as the inorganic semiconductor material, for example, an oxide including at least one element of Li, Na, Ba, Ca, Sr, Yb, Al, Ga, In, Cd, Mg, Si, Ta, Sb, and Zn , Nitrides, oxynitrides, and the like, and one or more of these can be used in combination.

  The average thickness of the electron injection layer 7 is not particularly limited, but is preferably about 0.1 to 1000 nm, more preferably about 0.5 to 100 nm, and further preferably about 1 to 50 nm. . Thereby, the resistance of the electron injection layer 7 is reduced while preventing the mechanical strength of the electron injection layer 7 from being lowered and the film formation time from becoming unnecessarily long, and the light emitting element 1 (display device 100). High-speed response can be realized.

The sealing member 9 is provided via a sealing material 10 so as to cover the light emitting element 1 (anode 3, hole transport layer 4, light emitting layer 5, intermediate layer 6, electron injection layer 7 and cathode 8). Is hermetically sealed and has a function of blocking oxygen and moisture.
By providing such a sealing member 9, effects such as improvement in reliability of the light emitting element 1 and prevention of deterioration / deterioration (improvement in durability) can be obtained.

Examples of the constituent material of the sealing member 9 include Al, Cr, Nb, alloys containing these, silicon oxide, various resin materials, and the like.
In addition, when using the material which has electroconductivity as a constituent material of the sealing member 9, in order to prevent a short circuit, it is preferable to use the thing excellent in insulation as the sealing material 10. FIG.
As such a sealing material 10, what comprises a thermosetting resin etc., such as an epoxy resin, can be used suitably, for example.

Next, the configuration of the intermediate layer 6 provided between the light emitting layer 5 and the electron injection layer 7 will be described.
In the present embodiment, the intermediate layer 6 is composed mainly of an ion trapping substance 61 and an organic compound (electron transport material) 62 having an electron transport property, and the electron transport material 62 is composed of an unshared electron pair. It is composed of an organic compound having an electron transport property of 1 or less.
Thus, by making the intermediate layer 6 contain an electron transport material, the intermediate layer 6 has a function of transporting electrons injected from the cathode 8 through the electron injection layer 7 to the light emitting layer 5 (electrons). Exhibits transportability.

Further, as described above, when the electron injection layer 7 and the cathode 8 are configured to include a metal element such as alkali metal and silver, respectively, the metal element such as alkali metal and silver is ionized. The generated alkali metal ions and metal ions diffuse into the intermediate layer 6.
Furthermore, by making the intermediate layer 6 contain the organic compound 62, alkali metal ions contained in the catalyst and solvent used when synthesizing the organic compound 62 are mixed in the intermediate layer 6. .
Therefore, the intermediate layer 6 includes alkali metal ions and metal ions diffused from various functional layers such as the electron injection layer 7 and the cathode 8, and alkali metal ions mixed when the organic compound 62 is synthesized. ing.

  Therefore, the intermediate layer 6 is configured to include an ion trapping substance 61 that is a substance having a function of trapping ions, whereby alkali metal ions and metal ions contained in the intermediate layer 6 are trapped by the ion trapping substance 61. can do. As a result, the metal ions are further prevented from moving through the intermediate layer 6 and diffusing into the light emitting layer 5, and the deterioration of the light emission characteristics due to the metal ions diffusing into the light emitting layer 5 can be prevented.

Further, by adopting a configuration in which the ion trapping substance 61 is dispersed in the organic compound 62, the ion trapping substance 61 may be referred to as a metal ion such as an alkali metal ion or a silver ion (hereinafter simply referred to as “metal ion”). ) And the organic compound 62 is interposed between the adjacent ion trapping portions 61, so that the transfer of metal ions between these ion trapping substances 61 can be reliably prevented.
The ion-trapping substance 61 that has captured the metal ions functions as a dopant in the intermediate layer 6, and the effect of improving the electron transport property of the intermediate layer 6 is also obtained.

Examples of the ion trapping substance 61 include an annular structure (ionophore) that traps the ions in the inner space, an SO ₃ ⁻ group, a CO ₂ ⁻ group, a PO ₄ H ⁻ group, and an NH ₃ ⁺ group that are electrically coupled to the ions. Although what has such an ionic group etc. is mentioned, what has an ionophore is especially preferable. By using a material having a cyclic structure as the ion trapping substance 61, when capturing the metal ion, it is possible to capture and hold the metal ion more reliably without releasing other ions such as hydrogen ions. .

Moreover, as this cyclic structure (ionophore), for example, a structure containing at least one hetero atom (heteroatom) such as an oxygen atom, a nitrogen atom, a sulfur atom and a phosphorus atom (that is, a methylene group is bonded to an oxygen atom) Atoms, nitrogen atoms, sulfur atoms, phosphorus atoms and other heteroatoms), derivatives thereof, those composed only of methylene groups (hydrocarbon rings), and the like. Those bonded by an atom, nitrogen atom, sulfur atom and phosphorus atom and derivatives thereof are preferred. Such a cyclic structure is preferable because it has a very high ion trapping ability. Further, there is an advantage that the size of the ring (inner space) and the flexibility of the ring can be easily adjusted, and the synthesis of such a cyclic structure can be performed relatively easily.
In the present specification, a hetero atom refers to an atom constituting a ring of a cyclic structure (heterocyclic compound) excluding a carbon atom. For example, as described above, an oxygen atom, a nitrogen atom , Sulfur atom and phosphorus atom.

As such a cyclic structure (ionophore) containing a heteroatom, for example, it has 6 or more carbon atoms and 2 or more heteroatoms in the ring constituting the cyclic structure. Are listed.
Specifically, a crown ether type represented by the following chemical formula 1, a propylene glycol type represented by the following chemical formula 2, an azacrown type represented by the following chemical formula 3, a thioether type represented by the chemical formula 4 below, And those derived from the nature represented by the following chemical formula 5 and those having a plurality of crown rings as represented by the chemical formula 6 below.

In addition, what connected the some crown ring represented by said Chemical formula 6 includes what connected the some crown ring directly, and what connected the some crown ring via the connection structure.
Here, for example, if the number of n and m in each general formula increases, the annular structure (size of the inner space) increases, and the diameter of metal ions that can be captured tends to increase. Moreover, when an aryl group or an unsaturated bond is included in the cyclic structure, the flexibility of the cyclic structure tends to decrease.

  Therefore, when using those having these cyclic structures as the ion trapping substance 61, metal ions expected to exist in the intermediate layer 6, that is, silver ions expected to diffuse from the cathode 8 are used. Depending on the type and / or ion diameter of the metal ions, the alkali metal ions expected to diffuse from the electron injection layer 7 and the alkali metal ions expected to be mixed into the intermediate layer 6 as impurities And the size of the ring (the number of n or m) is preferably selected. In this way, by selecting the type of ring and the size of the ring (the number of n and m) according to the type and / or ion diameter of the metal ion, the metal ion to be captured can be reliably captured. can do.

Specifically, it is preferable to select an ion trapping substance having a cyclic structure in consideration of the following points.
I: When alkali metal ions are predicted to be mixed as impurities in the intermediate layer 6 and / or when alkali metal ions are predicted to diffuse from the electron injection layer 7, the alkali metal ions are captured. The ion-trapping substance 61 having a ring structure to be obtained is selected.

Specifically, the ion diameters of alkali metal ions such as Li ⁺ , Na ⁺ , K ⁺ , and Cs ⁺ are large in the order of Li ⁺ <Na ⁺ <K ⁺ <(Cs), It is selectively captured by a 15-membered ring, an 18-membered ring or a 21-membered crown ether ring. Therefore, when Li ⁺ , Na ⁺ , K ⁺ , and Cs ⁺ are expected to diffuse (mix) into the intermediate layer 6, n is 2, 3, 4, 5 as the ion trapping material 61, respectively. The one represented by the above chemical formula 1 (a) is used.

  Further, the ion trapping substance represented by the chemical formula 1 (b), the ion trapping substance represented by the chemical formula 1 (c), the ion trapping substance represented by the chemical formula 2 and the ion trapping represented by the chemical formula 3 Each of the substance and the ion trapping substance represented by Chemical Formula 6 has a ring structure similar to a crown ether ring or a crown ether ring, and all of them can trap alkali metal ions. Among these, the ion-trapping substance represented by the chemical formula 6 (b) has a structure in which the crown ring is doubled (a structure in which two crown rings are directly connected), so that an alkali metal ion Can be confined by a double crown ring, and alkali metal ions can be firmly captured.

Further, the ion-trapping substances represented by the chemical formula 5 (naturally-occurring enniatin-B (the chemical formula 5 (a)) and nonactin (the chemical formula 5 (b))) are complexed with Na ⁺ and K ⁺ in the cell membrane. It is related to formation and traps these alkali metal ions efficiently.
Therefore, the ion trapping substance having these cyclic structures can be suitably used as the ion trapping substance 61 when alkali metal ions are expected to be present in the intermediate layer 6.
By using the ion trapping substance 61 having the above-described ring structure, alkali metal ions present in the intermediate layer 6 can be reliably trapped by the ion trapping substance 61, and the alkali metal ions are emitted to the light emitting layer 5. Can be reliably prevented.

II: When the cathode 8 is made of a conductive material containing a metal element such as silver and the metal ions are expected to diffuse into the intermediate layer 6, the metal ions derived from the cathode 8 can be captured. An ion trapping substance 61 having a ring structure is selected.
Since metal ions such as silver ions contained in the cathode 8 have a larger ion diameter than alkali metal ions, ions having a diameter larger than that of an ion trapping substance having a cyclic structure capable of trapping alkali metal ions are targeted. It is easy to be trapped by an ion trapping material having a cyclic structure.

Specifically, since the ion trapping substance having a cyclic structure (of the azacrown type) represented by Chemical Formula 3 can capture a relatively large metal ion by selecting the number of n, The gate electrode 50 is suitably used as an ion trapping material having a cyclic structure used when a metal element is contained.
In addition, an ion trapping substance having a (sulfide-based) cyclic structure represented by the above chemical formula 4 in which the number of n is 4 selectively captures silver ions. Therefore, when the cathode 8 contains silver, it can be suitably used as the ion trapping substance 61 having a cyclic structure.

  In addition, the ion trapping substance having a ring structure represented by the chemical formula 6 (a) is changed into a U-shape when irradiated with light, and two crown rings face each other. In this state, since ions can be sandwiched between two crown rings, ions larger than the ion diameter determined by the size of the crown ring can be captured. For this reason, the ion trapping substance 61 having the ring structure represented by the chemical formula 6 (a) is in a state where the two crown rings are opposed to each other, whereby the ion trapping substance 61 in the case where the cathode 8 contains a metal element. Is preferably used.

By using the ion trapping substance 61 having the above-described ring structure, the metal ions derived from the cathode 8 diffused in the intermediate layer 6 can be reliably trapped by the ion trapping substance 61, and the light emitting layer of this metal ion 5 can be reliably prevented.
Moreover, when the ion-trapping substance 61 is provided with a cyclic structure (ionophore), it is preferable that the ion-trapping substance 61 further has a coordination structure that coordinates to a metal ion trapped in the cyclic structure. Coordination structure coordinates with metal ions trapped in the ring structure, so that the metal ions are capped and hold the metal ions trapped in the ring structure more reliably. Can do.

Moreover, a larger-sized space can be ensured by the annular structure and the coordination structure. For this reason, a larger size metal ion can be captured by the ion capturing material 61 without increasing the size of the annular structure.
Specific examples of the ion trapping substance 61 having such a coordination structure include the following chemical formulas 7 and 8. This is an example, and the oxygen atom contained in the coordination structure portion may be changed to an atom having another unshared electron pair such as a nitrogen atom or a phosphorus atom.

Moreover, the side chain may be introduce | transduced as needed to the ion trapping substance provided with the above cyclic structures. Thereby, various characteristics can be imparted to the ion-trapping substance having a ring structure. For example, when an alkyl group is introduced as a side chain, the solubility of an ion-trapping substance having a cyclic structure in a solvent can be controlled by changing the number of carbon atoms. For example, in the case of an ion-trapping substance having a (crown ether type) cyclic structure represented by the above chemical formula 1 (a), such a side chain is converted into nitrogen by changing at least one of oxygen to nitrogen. It can introduce | transduce by making it connect with at least 1 of the carbon between oxygen, etc., etc. The side chain is not limited to an alkyl group and may have an aromatic ring such as a benzene ring.
Further, as an ion trapping substance having a cyclic structure, as represented by the following chemical formula 9, a polymer of a derivative of the compound represented by the chemical formula 1 (a) (crown ether derivative), that is, a heavy compound having a cyclic structure. A coalescence or the like can also be used. Thereby, the following effects are obtained.

  That is, when a relatively low molecular weight ion-trapping substance is present in the vicinity of the interface with the light-emitting layer 5, there is a possibility that the metal ions are diffused into the light-emitting layer 5 while being captured. The metal ions diffused into the light emitting layer 5 while being captured by the ion trapping substance may cause a decrease in the light emission characteristics of the light emitting layer 5. On the other hand, since the polymer having a cyclic structure has a high molecular weight, it is difficult to move in the intermediate layer 6, and it is possible to reliably prevent diffusion into the light emitting layer 5 while capturing metal ions. it can. In the case of such a polymer, the ionic species captured by each monomer is substantially the same as the corresponding cyclic structure.

  Moreover, in this polymer, when a metal ion is trapped in the cyclic part (crown ether ring), electrons move from the thiophene group to the cyclic part side, so that the electrons are easily taken into the thiophene group side. When electrons are taken into the thiophene group, the thiophene group is polymerized, and a large number of thiophene groups are connected in a chain, so that the electrons easily flow in the extending direction of the chain. As a result, the effect of improving the electron transport ability of the intermediate layer can also be obtained.

In addition, although the polymer represented by the chemical formula 9 has one thiophene group for one crown ether, a polymer having two thiophene groups for one crown ether may be used. it can.
Moreover, as an ion capture | acquisition substance provided with cyclic structure, in addition to what is equipped with the cyclic structure (crown ring) as shown in the said Chemical formula 1-Chemical formula 9, for example, the cyclic compound (calixarene) represented by following Chemical formula 10 is shown. Can be used.

Among these, those in which n is 4, and R ¹ is tert-butyl group have excellent scavenging ability for alkali metal ions, and ion trapping is expected when alkali metal ions are expected to be present in the intermediate layer 6 It is suitably used as a substance.
In addition, as the ion trapping substance having a cyclic structure, a cyclam (1,4,8,11-tetrazacyclote-tradecane), cyclodextrin, or the like can be used.

The ion trapping substance 61 can be used alone or in combination of two or more. For example, when it is expected that alkali metal ions are mixed into the intermediate layer 6 as impurities and metal ions such as silver ions are diffused from the cathode 8, ions that can capture the alkali metal ions. It is preferable to use a combination of a trapping substance and an ion trapping substance capable of trapping metal ions derived from the cathode 8. Thereby, the diffusion of metal ions from the intermediate layer 6 to the light emitting layer 5 can be more reliably prevented, and the deterioration of the light emission characteristics of the light emitting layer 5 can be more reliably prevented or suppressed.
In this case, the ratio of the ion trapping material capable of trapping alkali metal ions and the ion trapping material capable of trapping metal ions derived from the cathode 8 is preferably about 10: 1 to 1:20. More preferably, it is about ˜1: 5. Thereby, both alkali metal ions and metal ions derived from the cathode 8 can be efficiently captured.

The ion trapping substance 61 as described above is dispersed in the electron transport material in the intermediate layer 6. Thus, by making the intermediate layer 6 include an electron transport material, the intermediate layer 6 can function as an electron transport layer for transporting electrons injected from the electron injection layer 7 to the light emitting layer 5. it can.
In the present embodiment, this electron transport material is characterized in that the main material is an organic compound 62 in which the number of unshared electron pairs having a function of transporting electrons is 1 or less.

  Here, when the electron transport material is an organic compound having two or more unshared electron pairs, the organic compound can be bonded to a metal ion. That is, metal ions present in the intermediate layer 6 can be captured by an organic compound having two or more unshared electron pairs. Therefore, even if a metal ion is trapped by the ion trapping substance 61 as described above, the metal ion is exchanged with an organic compound having two or more unshared electron pairs adjacent to the ion trapping substance 61. Will be. As a result, the metal ions diffuse in the intermediate layer 6 via the organic compound having two or more unshared electron pairs and the ion trapping substance 61, and finally diffuse from the intermediate layer 6 to the light emitting layer 5. . Therefore, the light emission characteristics of the light emitting layer 5 are deteriorated.

On the other hand, when the electron transport material is composed mainly of the organic compound 62 having the number of unshared electron pairs having a function of transporting electrons of 1 or less, the organic compound 62 having the number of unshared electron pairs of 1 or less. Is difficult to capture metal ions. Therefore, if the intermediate layer 6 is configured such that the ion trapping substance 61 is dispersed in the organic compound 62, the metal ions once trapped by the ion trapping substance 61 are delivered via the organic compound 62. Therefore, the state in which the metal ions are held by the ion trapping substance 61 can be reliably maintained. As a result, diffusion of metal ions from the intermediate layer 6 to the light emitting layer 5 can be reliably prevented.
Such an organic compound 62 is sufficient if the number of unshared electron pairs is 1 or less, but preferably does not have an unshared electron pair. Thereby, since the delivery of metal ions via the organic compound 62 can be more reliably prevented, the above-described effects can be more reliably obtained.

Examples of the organic compound 62 having the number of unshared electron pairs having a function of transporting electrons of 1 or less include fullerene and tris (8-quinolinolato) aluminum (Alq ₃ ), and one of these or Two or more kinds can be used in combination. Such fullerenes and tris (8-quinolinolato) aluminum are excellent in electron transport properties and hardly capture metal ions. For this reason, by using these organic compounds as the electron transport material, the metal ions in the intermediate layer 6 can be reliably captured and held by the ion trapping substance 61. Further, the intermediate layer 6 has excellent electron transport capability.

  Further, the content (content ratio) of the ion trapping substance 61 in the intermediate layer 6 is preferably about 1 to 40 wt%, and more preferably about 20 to 30 wt%. By setting the content of the ion trapping substance 61 in the above range, metal ions are transferred between adjacent ion trapping substances 61 while exhibiting the function as an electron transporting layer for transporting electrons to the intermediate layer 6. Therefore, the metal ions can be more reliably trapped by the ion trapping substance 61. As a result, diffusion of metal ions from the intermediate layer 6 to the light emitting layer 5 can be reliably prevented.

The average thickness of the intermediate layer 6 is preferably about 20 to 100 nm, and more preferably about 30 to 60 nm. Thereby, diffusion of metal ions from other functional layers to the light emitting layer 5 can be reliably prevented, and the function of the intermediate layer 6 as an electron transporting layer can be reliably exhibited.
Such a light emitting element 1 is a top emission type that extracts light from the sealing member 9 side, but the light emitting element of the present invention is also a bottom emission type light emitting element that extracts light from the substrate 2 side. Can be applied.

The above light emitting element 1 can be manufactured as follows, for example.
[1A] First, a substrate 2 is prepared, and an anode 3 is formed on the substrate 2.
The anode 3 is, for example, a chemical vapor deposition method (CVD) such as plasma CVD or thermal CVD, a dry plating method such as vacuum deposition, a wet plating method such as electrolytic plating, a thermal spraying method, a sol-gel method, a MOD method, or a metal foil. It can be formed by using, for example, bonding.

[2A] Next, the hole transport layer 4 is formed on the anode 3.
The hole transport layer 4 is formed, for example, by supplying a hole transport layer forming material obtained by dissolving a hole transport material in a solvent or dispersing in a dispersion medium onto the anode 3 and then drying (desolvent or dedispersion medium). ).
As a method for supplying the hole transport layer forming material, for example, various coating methods such as a spin coating method, a roll coating method, and an ink jet printing method can be used. By using such a coating method, the hole transport layer 4 can be formed relatively easily.

  Examples of the solvent or dispersion medium used for preparing the hole transport layer forming material include inorganic solvents such as water and carbon disulfide, ketone solvents such as methyl ethyl ketone (MEK), acetone, and diethyl ketone, methanol, ethanol, and the like. Alcohol solvents, ether solvents such as diethyl ether and diisopropyl ether, cellosolv solvents such as methyl cellosolve and ethyl cellosolve, aliphatic hydrocarbon solvents such as hexane and pentane, and aromatic hydrocarbon solvents such as toluene and xylene , Aromatic heterocyclic compound solvents such as pyridine and pyrazine, amide solvents such as N, N-dimethylformamide (DMF) and N, N-dimethylacetamide (DMA), halogen compound solvents such as chlorobenzene and dichloromethane, acetic acid Ester solvents such as ethyl and methyl acetate, dimethyl Examples include sulfur compound solvents such as sulfoxide (DMSO) and sulfolane, nitrile solvents such as acetonitrile and propionitrile, various organic solvents such as organic acid solvents such as formic acid and acetic acid, and mixed solvents containing these. It is done.

The drying can be performed, for example, by standing in an atmospheric pressure or a reduced pressure atmosphere, heat treatment, or blowing an inert gas.
The hole transport layer 4 can also be formed by a vapor phase process using, for example, a CVD method, a dry plating method such as vacuum deposition or sputtering.
Prior to this step, the upper surface of the anode 3 may be subjected to oxygen plasma treatment. Thereby, it is possible to impart lyophilicity to the upper surface of the anode 3, remove (clean) organic substances adhering to the upper surface of the anode 3, adjust the work function near the upper surface of the anode 3, and the like. .
Here, the oxygen plasma treatment conditions include, for example, a plasma power of about 100 to 800 W, an oxygen gas flow rate of about 50 to 100 mL / min, a conveyance speed of the member to be treated (anode 3) of about 0.5 to 10 mm / sec, and a substrate. The temperature of 2 is preferably about 70 to 90 ° C.

[3A] Next, the light emitting layer 5 is formed on the hole transport layer 4 (one surface side of the anode 3).
For example, the light emitting layer 5 is dried (desolvent or dedispersion medium) after supplying a light emitting layer forming material obtained by dissolving a light emitting material in a solvent or dispersing in a dispersion medium onto the hole transport layer 4. Can be formed.
The method for supplying the light emitting layer forming material and the method for drying are the same as those described in the formation step [2A] of the hole transport layer 4.

  When the light emitting material as described above is used, a nonpolar solvent is suitable as the solvent or dispersion medium used for preparing the light emitting layer forming material, for example, xylene, toluene, cyclohexylbenzene, dihydrobenzofuran, trimethyl. Aromatic hydrocarbon solvents such as benzene and tetramethylbenzene, aromatic heterocyclic solvents such as pyridine, pyrazine, furan, pyrrole, thiophene and methylpyrrolidone, and aliphatic hydrocarbons such as hexane, pentane, heptane and cyclohexane A solvent etc. are mentioned, These can be used individually or as a mixed solvent containing these.

[4A] Next, the intermediate layer 6 is formed on the light emitting layer 5.
The intermediate layer 6 is formed by, for example, dissolving the ion-trapping substance 61 as described above and the organic compound 62 having the number of unshared electron pairs having a function of transporting electrons of 1 or less in a solvent or dispersing in a dispersion medium. It can be formed by supplying the intermediate layer forming material onto the light emitting layer and then drying (desolving or dedispersing medium).
The method for supplying the intermediate layer forming material, the solvent or dispersion medium used for preparing the intermediate layer forming material, and the drying method are the same as those described in the formation step [2A] of the hole transport layer 4.

[5A] Next, the electron injection layer 7 is formed on the intermediate layer 6 (on the side opposite to the light emitting layer).
When an inorganic material is used as the constituent material of the electron injection layer 7, the electron injection layer 7 is formed by, for example, a vapor phase process using a CVD method, a dry plating method such as vacuum vapor deposition or sputtering, and application and baking of inorganic fine particle ink. Etc. can be used.
[6A] Next, the cathode 8 is formed on the electron injection layer 7.
The cathode 8 can be formed by using, for example, a vacuum deposition method, a sputtering method, joining of metal foils, application and firing of metal fine particle ink, or the like.
The light emitting element 1 is obtained through the steps as described above.
Finally, the sealing member 9 is placed in a state where the sealing material 10 is interposed so as to cover the light emitting element 1 obtained, and the sealing material 10 is cured to be bonded to the substrate 2.

<< Second Embodiment >>
Next, a second embodiment of the light emitting device of the present invention will be described.
FIG. 2 is a view schematically showing a longitudinal sectional view of a second embodiment of the light emitting device of the present invention. In the following description, for convenience of explanation, the upper side in FIG. 2 will be described as “upper” and the lower side as “lower”.
Hereinafter, the second embodiment will be described with a focus on differences from the first embodiment, and description of similar matters will be omitted.
The light-emitting element 1 shown in FIG. 2 has a structure in which an intermediate layer 6 ′ is different from the intermediate layer 6 described in the first embodiment, and an electron transport layer 11 is provided between the electron injection layer 7 and the intermediate layer 6 ′. Except for this, it is the same as the light emitting device of the first embodiment.

Hereinafter, the configurations of the electron transport layer 11 and the intermediate layer 6 ′ will be described.
The electron transport layer 11 has a function of transporting electrons injected from the electron injection layer 7 to the intermediate layer 6 ′.
The constituent material (electron transport material) of the electron transport layer 11 is not particularly limited. For example, 1,3,5-tris [(3-phenyl-6-tri-fluoromethyl) quinoxalin-2-yl] benzene ( Benzene compounds such as TPQ1), naphthalene compounds, phenanthrene compounds, chrysene compounds, perylene compounds, various metal complexes such as complexes having benzoxazole or benzothiazole as a ligand, etc. One or two or more of them can be used in combination.
Such an electron transport layer 11 is also mixed with alkali metal ions contained in a catalyst and a solvent used when synthesizing an electron transport material.
Although the average thickness of such an electron carrying layer 11 is not specifically limited, It is preferable that it is about 1-100 nm, and it is more preferable that it is about 10-50 nm.

  In the present embodiment, the intermediate layer 6 ′ is composed mainly of the ion trapping substance 61 and the organic compound 62 having a function of transporting electrons as in the first embodiment, The ion trapping substance 61 and the insulating polymer 63 are configured as main materials, and the insulating polymer 63 is configured such that the monomer component constituting the insulating polymer mainly includes one or less unshared electron pairs. Has been.

  The ion trapping substance 61 is a substance having a function of trapping ions. Therefore, by providing the intermediate layer 6 ′ containing the ion trapping substance 61 between the electron transport layer 11 and the light emitting layer 5, the cathode 8, the electron injection layer 7, and the electron transport layer 11 to the intermediate layer 6 ′. The metal ions that have diffused into the metal layer, and further, the metal ions derived from the insulating polymer 63 contained in the intermediate layer 6 ′ can be captured by the ion capturing material 61. That is, the intermediate layer 6 'functions as a metal ion trap layer. For this reason, it is possible to prevent the metal ions from further diffusing into the light emitting layer 5 and to prevent the light emission characteristics from being deteriorated due to the metal ions diffusing into the light emitting layer 5.

As the ion-trapping substance 61, the same thing as the said 1st Embodiment can be mentioned.
By adopting a configuration in which such an ion trapping substance 61 is dispersed in the insulating polymer 63, the ion trapping substance 61 can be reliably supported in the intermediate layer 6 ′. Thereby, it can prevent reliably that the ion trapping substance 61 transfers to the light emitting layer 5 in the state which captured the metal ion.

Further, the ion trapping substance 61 may be the same as that in the first embodiment, or may be a copolymer of the polymer represented by the chemical formula 9 and the insulating polymer 63. Also in this case, since the copolymer is a polymer like the polymer represented by the chemical formula 9, it is difficult to move in the intermediate layer 6 ′, and the metal ions are captured in the light emitting layer 5 in a captured state. It can prevent more reliably that it transfers and it becomes that the light emission characteristic falls.
Further, in the intermediate layer 6 ′ of the present embodiment, the ion trapping substance 61 is dispersed in a matrix composed of the insulating polymer 63 instead of being dispersed in the electron transporting material. The monomer component that constitutes is characterized in that the number of unshared electron pairs is 1 or less.

  Here, if the insulating polymer 63 is composed mainly of a monomer component constituting the insulating polymer 63 having two or more unshared electron pairs, the monomer component having two or more unshared electron pairs is: Can bind to metal ions. That is, the metal ions present in the intermediate layer 6 can be captured by the monomer component having two or more unshared electron pairs. Therefore, even if a metal ion is trapped by the ion trapping substance 61 as described above, the metal ion is exchanged between the monomer component adjacent to the ion trapping substance 61 and having two or more unshared electron pairs. Will be. As a result, the metal ions diffuse in the intermediate layer 6 ′ via the monomer component having two or more unshared electron pairs and the ion trapping substance 61, and finally, from the intermediate layer 6 ′ to the light emitting layer 5. Spread. Therefore, the light emission characteristics of the light emitting layer 5 are deteriorated.

On the other hand, when the monomer component constituting the insulating polymer 63 is composed mainly of those having 1 or less lone pairs, the monomer component having 1 or less lone pairs is a metal ion. Hard to catch. Therefore, if the intermediate layer 6 is configured such that the ion trapping substance 61 is dispersed in the insulating polymer 63 composed of such a monomer component as a main material, once the metal ions trapped by the ion trapping substance 61 are It can be surely prevented from being delivered via the insulating polymer 63, and the state in which the metal ions are held by the ion trapping substance 61 can be reliably maintained. As a result, diffusion of metal ions from the intermediate layer 6 to the light emitting layer 5 can be reliably prevented.
The monomer component constituting such an insulating polymer 63 may be one having an unshared electron pair of 1 or less, but preferably has no unshared electron pair. Thereby, since the delivery of metal ions through the insulating polymer 63 can be more reliably prevented, the above-described effects can be more reliably obtained.

  Examples of the insulating polymer 63 composed of a monomer component having 1 or less lone pair, that is, the insulating polymer 63 containing a monomer component having 1 or less lone pair include, for example, polyethylene, polypropylene, polyisobutylene, In addition to polyolefins composed of chain aliphatic hydrocarbons such as polybutene, polystyrene and the like, polyolefins having cyclic aliphatic hydrocarbons (hereinafter abbreviated as “alicyclic hydrocarbon-containing polymer”) are also included. Can be mentioned.

  Among these, alicyclic hydrocarbon-containing polymers are polymers with high pressure resistance, low moisture absorption, high heat resistance, high density, solvent selectivity, etc., a rigid main chain and a high glass transition temperature. Therefore, the function of preventing diffusion of metal ions can be imparted to the matrix itself composed of the alicyclic hydrocarbon-containing polymer. Therefore, when an alicyclic hydrocarbon-containing polymer is used, diffusion of metal ions can be reliably prevented by the matrix, and even if metal ions diffuse in the matrix, the metal ions diffused by the ion trapping substance 61 can be reliably prevented. Can be captured. As a result, diffusion of metal ions from the intermediate layer 6 ′ to the light emitting layer 5 can be prevented or suppressed more reliably.

  The cyclic aliphatic hydrocarbon contained in such an alicyclic hydrocarbon-containing polymer is preferably one having 3 to 20 carbon atoms, more preferably one having 4 to 15 carbon atoms. Specifically, for example, cyclopentane, cyclohexane, cycloheptane, cyclodecane, norbornene, dicyclopentadiene, tetracyclododecene, and the like can be used, and one or more of these can be used in combination. . Among these, those containing norbornene are preferable. Since norbornene has a bulky molecular structure, polyolefin can be easily converted into an amorphous structure due to steric hindrance. As a result, a homogeneous intermediate layer 6 'can be obtained.

When the molecular weight of the alicyclic hydrocarbon-containing polymer is measured by gel permeation chromatography (GPC), the weight average molecular weight (Mw) in terms of polyisoprene is 1 × 10 ^{4 to} 5 × 10 ^6. Preferably, it is 5 × 10 ⁴ to 1 × 10 ⁶ . By setting the molecular weight within such a range, a high-density intermediate layer 6 ′ can be formed, so that diffusion of metal ions from the intermediate layer 6 ′ can be prevented.
Examples of such alicyclic hydrocarbon-containing polymers include compounds represented by the following chemical formula 11.

The content (content ratio) of the ion trapping substance 61 in the intermediate layer 6 ′ is preferably about 1 to 40 wt%, and more preferably about 20 to 30 wt%. By setting the content of the ion trapping substance 61 within the above range, it is possible to reliably prevent the metal ions from being transferred between the adjacent ion trapping substances 61. It can be captured more reliably. As a result, diffusion of metal ions from the intermediate layer 6 to the light emitting layer 5 can be reliably prevented.
In the organic EL element having such an intermediate layer 6 ′, electrons transported by the electron transport layer 11 pass through the intermediate layer 6 ′ by the tunnel effect and are supplied (injected) to the light emitting layer 5.

For this reason, the intermediate layer 6 ′ is thin enough to allow electrons to pass through by the tunnel effect. Specifically, the average thickness of the intermediate layer 6 ′ is preferably about 5 to 10 nm. If the thickness of the intermediate layer 6 ′ is set to be smaller than the above range, it is difficult to form the intermediate layer 6 ′ uniformly, and there is a possibility that sufficient ion trapping ability may not be obtained in the formed intermediate layer 6 ′. is there. On the other hand, if the intermediate layer 6 ′ is too thick, electrons from the electron transport layer 11 are difficult to pass through the intermediate layer 6 ′, and the efficiency of injecting electrons into the light emitting layer 5 may be insufficient.
In such a light emitting device 1, for example, by omitting the step [4A], the intermediate layer 6 ′ is replaced with the intermediate layer 6 by performing the following step [4B-1] and the following step [4B-2]. Further, it can be manufactured in the same manner as the light emitting device of the first embodiment except that the electron transport layer 11 is formed.

[4B-1] An intermediate layer 6 ′ is formed on the light emitting layer 5 formed in the step [3A].
For example, the intermediate layer 6 ′ is made of an intermediate layer forming material formed by dissolving the ion trapping substance 61 and the insulating polymer 63 or a precursor thereof in a solvent or dispersing in a dispersion medium on the light emitting layer 5. After being supplied to the film, it can be formed by subjecting this coating film to post-treatment (for example, heating, irradiation with infrared rays, application of ultrasonic waves, etc.) as necessary.
The method for supplying the intermediate layer forming material, the solvent or dispersion medium used for preparing the intermediate layer forming material, and the drying method are the same as those described in the formation step [2A] of the hole transport layer 4.

[4B-2] Next, the electron transport layer 11 is formed on the intermediate layer 6 '.
The electron transport layer 11 is dried (desolvent or dedispersion medium) after supplying an electron transport layer forming material obtained by, for example, dissolving an electron transport material in a solvent or dispersing in a dispersion medium onto the intermediate layer 6 ′. Can be formed.
The method for supplying the electron transport layer forming material, the solvent or dispersion medium used for the preparation of the electron transport layer forming material, and the drying method are the same as those described in the formation step [2A] of the hole transport layer 4.

The electron transport layer 11 can also be formed by a vapor phase process using, for example, a CVD method, a dry plating method such as vacuum deposition or sputtering.
Also by the light emitting device of the second embodiment, the same operation and effect as the light emitting device 1 of the first embodiment can be obtained.
In the first embodiment, the intermediate layer 6 functions as both a metal ion trap layer and an electron transport layer, whereas in the second embodiment, the ion is independent of the electron transport layer 11. An intermediate layer 6 ′ containing a trapping substance is provided. For this reason, about the electron transport material used for the electron carrying layer 11, the number of unshared electron pairs is not restricted to 1 or less, Various electron transport materials can be used. That is, the selection range of the electron transport material can be expanded.

Such a light emitting element 1 can be used as, for example, a light source. Further, a display device (the light emitting device of the present invention) can be configured by arranging a plurality of light emitting elements 1 in a matrix.
The driving method of the display device is not particularly limited, and may be either an active matrix method or a passive matrix method.

Next, an example of a display device to which the light emitting device of the present invention is applied will be described.
FIG. 3 is a longitudinal sectional view showing an embodiment of a display device to which the light emitting device of the present invention is applied.
The display device 100 shown in FIG. 3 includes a base body 20 and a plurality of light emitting elements 1 provided on the base body 20.

The base body 20 includes a substrate 21 and a circuit unit 22 formed on the substrate 21.
The circuit unit 22 includes a protective layer 23 made of, for example, a silicon oxide layer formed on the substrate 21, a driving TFT (switching element) 24 formed on the protective layer 23, a first interlayer insulating layer 25, And a second interlayer insulating layer 26.
The driving TFT 24 includes a semiconductor layer 241 made of silicon, a gate insulating layer 242 formed on the semiconductor layer 241, a gate electrode 243 formed on the gate insulating layer 242, a source electrode 244, and a drain electrode 245. have.
On such a circuit portion 22, the light emitting element 1 is provided corresponding to each driving TFT 24. Adjacent light emitting elements 1 are partitioned by a first partition wall portion 31 and a second partition wall portion 32.

In the present embodiment, the anode 3 of each light emitting element 1 constitutes a pixel electrode and is electrically connected to the drain electrode 245 of each driving TFT 24 by the wiring 27. Further, the cathode 8 of each light emitting element 1 is a common electrode.
Then, a sealing member (not shown) is bonded to the base 20 so as to cover each light emitting element 1, and each light emitting element 1 is sealed.
The display device 100 may be monochromatic display, and color display is also possible by selecting a light emitting material used for each light emitting element 1.
Such a display device 100 (the light emitting device of the present invention) can be incorporated into various electronic devices.

FIG. 4 is a perspective view showing a configuration of a mobile (or notebook) personal computer to which the electronic apparatus of the present invention is applied.
In this figure, a personal computer 1100 includes a main body 1104 provided with a keyboard 1102 and a display unit 1106 provided with a display. The display unit 1106 is rotatable with respect to the main body 1104 via a hinge structure. It is supported by.
In the personal computer 1100, the display unit included in the display unit 1106 is configured by the display device 100 described above.

FIG. 5 is a perspective view showing a configuration of a mobile phone (including PHS) to which the electronic apparatus of the present invention is applied.
In this figure, a cellular phone 1200 includes a plurality of operation buttons 1202, an earpiece 1204 and a mouthpiece 1206, and a display unit.
In the cellular phone 1200, the display unit is configured by the display device 100 described above.

FIG. 6 is a perspective view showing the configuration of a digital still camera to which the electronic apparatus of the present invention is applied. In this figure, connection with an external device is also simply shown.
Here, an ordinary camera sensitizes a silver halide photographic film with a light image of a subject, whereas a digital still camera 1300 photoelectrically converts a light image of a subject with an imaging device such as a CCD (Charge Coupled Device). An imaging signal (image signal) is generated.

A display unit is provided on the back of a case (body) 1302 in the digital still camera 1300, and is configured to display based on an imaging signal from the CCD, and functions as a finder that displays an object as an electronic image.
In the digital still camera 1300, the display unit is configured by the display device 100 described above.

A circuit board 1308 is installed inside the case. The circuit board 1308 is provided with a memory that can store (store) an imaging signal.
A light receiving unit 1304 including an optical lens (imaging optical system), a CCD, and the like is provided on the front side of the case 1302 (on the back side in the illustrated configuration).

When the photographer confirms the subject image displayed on the display unit and presses the shutter button 1306, the CCD image pickup signal at that time is transferred and stored in the memory of the circuit board 1308.
In the digital still camera 1300, a video signal output terminal 1312 and an input / output terminal 1314 for data communication are provided on the side surface of the case 1302. As shown in the figure, a television monitor 1430 is connected to the video signal output terminal 1312 and a personal computer 1440 is connected to the data communication input / output terminal 1314 as necessary. Further, the imaging signal stored in the memory of the circuit board 1308 is output to the television monitor 1430 or the personal computer 1440 by a predetermined operation.

In addition to the personal computer (mobile personal computer) in FIG. 4, the mobile phone in FIG. 5, and the digital still camera in FIG. 6, the electronic apparatus of the present invention includes, for example, a television, a video camera, a viewfinder type, Monitor direct-view video tape recorder, laptop personal computer, car navigation system, pager, electronic notebook (including communication function), electronic dictionary, calculator, electronic game device, word processor, workstation, video phone, security TV Monitors, electronic binoculars, POS terminals, devices equipped with touch panels (for example, cash dispensers and automatic ticket vending machines for financial institutions), medical devices (for example, electronic thermometers, blood pressure monitors, blood glucose meters, electrocardiographs, ultrasound diagnostic devices, internal Endoscope display device), fish finder, various measuring instruments, Vessels such (e.g., gages for vehicles, aircraft, and ships), a flight simulator, various monitors, and a projection display such as a projector.
As mentioned above, although the light emitting element of this invention, the light-emitting device, and the electronic device were demonstrated based on embodiment of illustration, this invention is not limited to these.
For example, in the light-emitting element of the present invention, one or more desired layers can be provided in at least one of the layers.

Next, specific examples of the present invention will be described.
In Table 1 shown below, specific ion trapping materials, organic compounds, types and contents of insulating polymers used in each example described below are listed and displayed.
1. Production of Light-Emitting Element Five light-emitting elements were produced in each of the following Examples and Comparative Examples.

Example 1A
<1> First, a transparent glass substrate having an average thickness of 0.5 mm was prepared.
<2> Next, an ITO electrode (anode) having an average thickness of 100 nm was formed on the substrate by sputtering.
And after immersing a board | substrate in order of acetone and 2-propanol and ultrasonically cleaning, the oxygen plasma process was performed.
<3> Next, after applying an aqueous dispersion of poly (3,4-ethylenedioxythiophene / styrene sulfonic acid) (PEDOT / PSS) on the ITO electrode by a spin coating method, Dried at 200 ° C. for 10 minutes under atmospheric pressure. Thereby, a hole transport layer having an average thickness of 60 nm was formed.

<4> Next, a xylene solution in which polyvinylcarbazole (PVK) and factory (2-phenylpyridine) iridium (Ir (ppy) ₃ ) are dissolved is applied onto the hole transport layer by a spin coating method. Then, heat treatment was performed on a hot plate at 130 ° C. for 10 minutes in a nitrogen atmosphere. Thereby, a light emitting layer having an average thickness of 70 nm was formed. The blending ratio of PVK and Ir (ppy) ₃ was 97: 3 by weight.

<5> Next, 12-crown-4 in which n is 2 in the above chemical formula 1 (a) as an ion trapping substance and fullerene as an electron transport material (an organic compound having a function of transporting electrons) A butyl acetate solution was prepared, and this butyl acetate solution was supplied onto the light emitting layer by an inkjet method, and then dried on a hot plate at 60 ° C. for 10 minutes. The blending ratio of fullerene and 12-crown-4 was 5: 1 by weight.
Thereby, an intermediate layer having an average thickness of 50 nm was formed.

<6> Next, on the intermediate layer, lithium fluoride (LiF) was formed by a vacuum evaporation method to form an electron injection layer having an average thickness of 5 nm.
<7> Next, Mg and Ag were simultaneously formed by a vacuum deposition method. As a result, a cathode having an average thickness of 200 nm made of an MgAg alloy was formed.
<8> Next, a glass protective cover (sealing member) was placed over the formed layers, and fixed and sealed with an epoxy resin.
The light emitting device was manufactured through the above steps.

(Example 2A)
A light emitting device was produced in the same manner as in Example 1A, except that the blending ratio of fullerene and 12-crown-4 was 3: 1 in the step <5>.
(Example 3A)
A light emitting device was manufactured in the same manner as in Example 1A, except that in the step <5>, cryptate-211 which is the chemical formula 6 (b) was used as the ion trapping substance.

(Example 4A)
A light emitting device was manufactured in the same manner as in Example 1A, except that in step <6>, the electron injection layer was formed using cesium fluoride (CsF).
(Example 5A)
In the step <5>, 21-crown-7 in which n is 5 in the above chemical formula 1 (a) is used as the ion trapping substance, and in the step <6>, the electron injection layer is made of cesium fluoride (CsF). A light emitting device was manufactured in the same manner as in Example 1A, except that it was formed using the above.

(Example 6A)
In the step <5>, cryptate-211 was used as an ion trapping substance, and in the step <6>, an electron injection layer was formed using cesium fluoride (CsF). A light emitting device was manufactured.
(Example 7A)
In the step <5>, except that the thiacrown ether in which n is 4 in the above chemical formula 4 (an ion trapping substance that selectively traps Ag ions) is used as the ion trapping substance, the same as in Example 1A, A light emitting device was manufactured.

(Example 8A)
Example 1A above, except that, in the step <5>, cryptate-211 as an ion trapping substance and thiacrown ether in which n is 4 in the above chemical formula 4 are mixed in a 1: 1 (weight ratio). A light emitting device was manufactured in the same manner as described above.
(Example 9A)
A light emitting device was manufactured in the same manner as in Example 1A, except that Alq ₃ was used as the electron transport material in the step <5>.

(Example 10A)
In step <5>, 21-crown-7 was used as an ion trapping substance, and Alq ₃ was used as an electron transport material. In step <6>, an electron injection layer was formed using cesium fluoride (CsF). Except for the above, a light-emitting element was manufactured in the same manner as in Example 1A.

(Comparative Example 1A)
A light emitting device was manufactured in the same manner as in Example 1A, except that the addition of 12-crown-4 was omitted in Step <5>.
(Comparative Example 2A)
A light emitting device was manufactured in the same manner as in Example 1A except that in the step <5>, bathocloproin represented by the following chemical formula 12 was used as the electron transport material.

(Comparative Example 3A)
In step <5>, the addition of 12-crown-4 was omitted, and in step <6>, the electron injection layer was formed using cesium fluoride (CsF). Thus, a light emitting device was manufactured.
(Comparative Example 4A)
In step <5>, 21-crown-7 is used as an ion trapping substance, and bathocloproin represented by the above formula 12 is used as an electron transport material. In step <6>, the electron injection layer is formed of cesium fluoride (CsF A light emitting device was manufactured in the same manner as in Example 1A except that the light emitting device was formed using the above.

(Example 1B)
Instead of the step <5>, the intermediate layer and the electron transport layer were formed by passing through the following step <5-1> and the following step <5-2>. A light emitting device was manufactured.
<5-1> A butyl acetate solution containing 12-crown-4 as an ion trapping substance and polystyrene as an insulating polymer is prepared, and this butyl acetate solution is supplied onto the light emitting layer by an inkjet method, and then hot It dried on the plate at 60 ° C. for 10 minutes. The blending ratio of fullerene and 12-crown-4 was 5: 1 by weight.
Thereby, an intermediate layer having an average thickness of 7 nm was formed.
<5-2> Next, 1,3,5-tris [(3-phenyl-6-tri-fluoromethyl) quinoxalin-2-yl] benzene (TPQ1) was vacuum-deposited to obtain an average thickness of 60 nm. An electron transport layer was formed.

(Example 2B)
A light emitting device was manufactured in the same manner as in Example 1B, except that the blending ratio of fullerene and 12-crown-4 was 3: 1 in the step <5-1>.
(Example 3B)
A light emitting device was manufactured in the same manner as in Example 1B, except that in the step <5-1>, cryptate-211 which is the chemical formula 6 (b) was used as the ion trapping substance.

(Example 4B)
A light emitting device was manufactured in the same manner as in Example 1B, except that, in step <6>, the electron injection layer was formed using cesium fluoride (CsF).
(Example 5B)
In the step <5-1>, 21-crown-7 in which n is 5 in the above chemical formula 1 (a) is used as the ion trapping substance, and in the step <6>, the electron injection layer is made of cesium fluoride ( A light emitting device was manufactured in the same manner as in Example 1B except that it was formed using CsF).

(Example 6B)
Similar to Example 1B, except that in the step <5-1>, cryptate-211 was used as the ion trapping substance, and in the step <6>, the electron injection layer was formed using cesium fluoride (CsF). Thus, a light emitting device was manufactured.
(Example 7B)
In the step <5-1>, the same procedure as in Example 1B was performed except that the thiacrown ether (ion trapping material that selectively traps Ag ions) in the above-described chemical formula 4 was used as the ion trapping material. Thus, a light emitting device was manufactured.

(Example 8B)
In the above-mentioned step <5-1>, the above-mentioned implementation was performed except that a mixture of cryptate-211 and thiacrown ether in which n is 4 in the above chemical formula (1: 1) (weight ratio) was used as an ion trapping substance. A light emitting device was manufactured in the same manner as in Example 1B.
(Example 9B)
A light emitting device was manufactured in the same manner as in Example 1B except that polyethylene was used as the insulating polymer in the step <5-1>.

(Example 10B)
In step <5-1>, 21-crown-7 is used as the ion trapping substance, and polyethylene is used as the insulating polymer. In step <6>, the electron injection layer is formed using cesium fluoride (CsF). A light emitting device was manufactured in the same manner as in Example 1B except that.

(Example 11B)
In the step <5-1>, a cycloolefin-containing polymer which is the above-described chemical formula 11 (e) (m is 200, n is 300, R ¹ and R ² are methyl groups) is used as the insulating polymer. A light emitting device was manufactured in the same manner as in Example 1B except that.
(Example 12B)
In the step <5-1>, 21-crown-7 is used as an ion-trapping substance, and the above-described chemical compound 11 (e) is used as an insulating polymer (m is 200, n is 300, R ¹ and R ² are methyl groups) A light-emitting device was prepared in the same manner as in Example 1B, except that each of the cycloolefin-containing polymers was one and the electron injection layer was formed using cesium fluoride (CsF) in the step <6>. Manufactured.

(Comparative Example 1B)
A light emitting device was manufactured in the same manner as in Example 1B, except that the addition of 12-crown-4 was omitted in the step <5-1>.
(Comparative Example 2B)
In the step <5-1>, a light emitting device was produced in the same manner as in Example 1B, except that polyvinylphenol (PVP) was used as the insulating polymer.

(Comparative Example 3B)
In Example <1>, except that the addition of 12-crown-4 was omitted in Step <5-1>, and the electron injection layer was formed using cesium fluoride (CsF) in Step <6>. Similarly, a light emitting device was manufactured.
(Comparative Example 4B)
In step <5-1>, 21-crown-7 is used as the ion trapping substance, polyvinylphenol (PVP) is used as the insulating polymer, and in step <6>, the electron injection layer is made of cesium fluoride (CsF). A light emitting device was produced in the same manner as in Example 1B, except that it was used.

2. Evaluation 2-1. Evaluation of luminous efficiency Immediately after production, a voltage of 8 V was applied between the anode and the cathode from the direct current power source, and the current value and luminance were measured. did. From these values, the luminous efficiency [cd / A] was determined.

Next, after leaving these light-emitting elements in the atmosphere (25 ° C.) for 30 days, the light emission efficiency [cd / A] was obtained by measuring the current value and the luminance again in the same manner as described above. .
In addition, calculation of luminous efficiency [cd / A] was performed about five light emitting elements in each Example and the comparative example.
Then, the luminous efficiencies immediately after the production and 30 days after the production measured in Examples 1A to 10A and Comparative Examples 2A to 4A, respectively, with the luminous efficiency immediately after the production measured in Comparative Example 1A and after 30 days as a reference value, respectively, Evaluation was made according to a four-stage criterion.
A: The luminous efficiency of Comparative Example 1A is 3.0 times or more. O: The luminous efficiency of Comparative Example 1A is 1.5 times or more and less than 3.0 times. Δ: The luminous efficiency of Comparative Example 1A. In contrast, 1.0 times or more and less than 1.5 times x: 0.8 times or more and less than 1.0 times the light emission efficiency of Comparative Example 1A

Further, the luminous efficiencies immediately after production and after 30 days measured in Examples 1B to 12B and Comparative Examples 2B to 4B, respectively, were determined using the luminous efficiencies immediately after production and after 30 days measured in Comparative Example 1B as the reference values. Evaluation was made according to a four-stage criterion.
A: The luminous efficiency of Comparative Example 1B is 3.0 times or more. O: The luminous efficiency of Comparative Example 1B is 1.5 times or more and less than 3.0 times. Δ: The luminous efficiency of Comparative Example 1B. In contrast, 1.0 times or more and less than 1.5 times x: 0.8 times or more and less than 1.0 times the light emission efficiency of Comparative Example 1B. It shows in Table 1 and Table 2.

As shown in Table 1 and Table 2, the light-emitting elements of each example had almost the same or slightly better results than the light-emitting elements of Comparative Example 1A or 1B in the luminous efficiency immediately after manufacture. However, particularly excellent results were obtained with the luminous efficiency after 30 days.
On the other hand, the light-emitting elements manufactured in the respective comparative examples were almost the same or inferior to the light-emitting efficiency immediately after manufacture and after 30 days with respect to the light-emitting elements of Comparative Example 1A or 1B. It was.
Thereby, in the light emitting element of this invention, it became clear that the diffusion of the metal ion from an intermediate | middle layer to a light emitting layer was prevented or suppressed suitably.

  Moreover, the tendency as mentioned above was recognized more notably in the light emitting elements manufactured in Examples 1A to 10A than in the light emitting elements manufactured in Examples 1B to 12B. This is presumably because the metal ions trapped by the ion trapping substance function in the intermediate layer (electron transport layer) as a dopant that improves the electron transport ability of the electron transport material contained in this layer. .

It is a figure which shows typically the longitudinal cross-section of 1st Embodiment of the light emitting element of this invention. It is a figure which shows typically the longitudinal cross-section of 2nd Embodiment of the light emitting element of this invention. It is a longitudinal cross-sectional view which shows embodiment of the display apparatus to which the light-emitting device of this invention is applied. 1 is a perspective view showing a configuration of a mobile (or notebook) personal computer to which an electronic apparatus of the present invention is applied. It is a perspective view which shows the structure of the mobile telephone (PHS is also included) to which the electronic device of this invention is applied. It is a perspective view which shows the structure of the digital still camera to which the electronic device of this invention is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Light emitting element 2 ... Substrate 3 ... Anode 4 ... Hole transport layer 5 ... Light emitting layer 6, 6 '... Intermediate layer 61 ... Ion trapping substance 62 ... Organic compound 63 ... Insulating polymer 7 ... Electron injection layer 8 ... Cathode 9 ... Sealing member 10 ... Sealing material 11 ... Electron transport layer 15 ... Laminate 100 ... Display device 20 ... Base 21 ... Substrate 22 ... Circuit part 23 …… Protective layer 24 …… Drive TFT 241 …… Semiconductor layer 242 …… Gate insulating layer 243 …… Gate electrode 244 …… Source electrode 245 …… Drain electrode 25 …… First interlayer insulating layer 26 …… Second Interlayer insulating layer 27 …… Wiring 31 …… First partition portion 32 …… Second partition portion 1100 …… Personal computer 1102 …… Keyboard 1104 …… Main body portion 1106 …… Display unit 1200 …… Cellular phone 1202 …… Operation buttons 1204 …… Entrance 1206 …… Transmission mouth 1300 ··· Digital still camera 1302 ··· Case (body) 1304 ··· Light receiving unit 1306 ··· Shutter button 1308 ··· Circuit board 1312 Video signal output terminal 1314 Input / output terminal for data communication 1430 Television monitor 1440 Personal computer

Claims (16)

The anode,
A cathode,
An organic light emitting layer provided between the anode and the cathode;
An intermediate layer provided between the cathode and the organic light emitting layer;
The light-emitting element, wherein the intermediate layer includes an ion-trapping substance capable of capturing metal ions and an organic compound having a number of unshared electron pairs having a function of transporting electrons of 1 or less.   The light emitting device according to claim 1, wherein the intermediate layer is formed by dispersing the ion trapping substance in the organic compound.   3. The light emitting device according to claim 1, wherein a content of the ion trapping substance in the intermediate layer is 1 to 40 wt%.   The light emitting device according to any one of claims 1 to 3, wherein an average thickness of the intermediate layer is 20 to 100 nm. The anode,
A cathode,
An organic light emitting layer provided between the anode and the cathode;
An intermediate layer provided between the cathode and the organic light emitting layer;
The intermediate layer includes an ion trapping material capable of trapping metal ions and an insulating polymer,
The light-emitting element, wherein the insulating polymer includes a monomer component having an unshared electron pair of 1 or less.   The light emitting device according to claim 5, wherein the intermediate layer is formed by dispersing the ion trapping substance in the insulating polymer.   The light emitting device according to claim 5 or 6, wherein a content of the ion trapping substance in the intermediate layer is 1 to 40 wt%.   The light emitting device according to claim 5, wherein an average thickness of the intermediate layer is 5 to 10 nm.   The light-emitting element according to claim 1, wherein the ion trapping substance is capable of trapping alkali metal ions contained in the intermediate layer. The cathode contains a metal element,
The light-emitting element according to claim 1, wherein the ion trapping substance is capable of trapping metal ions derived from the metal element. An electron injection layer containing an alkali metal compound is provided between the cathode and the intermediate layer,
The light-emitting element according to claim 1, wherein the ion trapping substance is capable of trapping alkali metal ions derived from the alkali metal compound.   The said ion trapping substance has a cyclic structure, The kind and magnitude | size of the said cyclic structure are selected according to the difference in the kind and / or ion diameter of the said metal ion. Light emitting element.   The light-emitting element according to claim 12, wherein the cyclic structure includes at least one of an oxygen atom, a nitrogen atom, a sulfur atom, and a phosphorus atom.   The light emitting device according to claim 13, wherein the ring structure has six or more carbon atoms and two or more at least one hetero atom in the ring.   A light-emitting device comprising the light-emitting element according to claim 1.   An electronic apparatus comprising the light emitting device according to claim 15.

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