WO2015092840A1 - Organic light-emitting element - Google Patents

Abstract

　The purpose of the present invention is to provide a high-efficiency coating-type white organic light-emitting element. The present invention is an organic light-emitting element having a first electrode, a second electrode, a light-emitting layer disposed between the first electrode and the second electrode, and a charge transport layer positioned adjacently with respect to the light-emitting layer; wherein the organic light-emitting element is characterized in that the charge transport layer adjacent to the light-emitting layer contains a light-emitting dopant, and the light-emitting dopant has a functional group for moving to the vicinity of the interface between the light-emitting layer and the charge transportation layer.

Description

Organic light emitting device

The present invention relates to an organic light emitting device.

The structure of the light emitting layer of the white light emitting organic LED (organic light emitting diode) includes a single layer structure and a laminated structure. As an example of a laminated structure, Patent Document 1 reports a laminated structure in which a hole transport layer is doped with a yellow dopant and a blue dopant is contained in a light emitting layer.

JP, 2013-065868, A

Methods of manufacturing the organic LED include a vapor deposition method and a wet method. In the vapor deposition method, as described in Patent Document 1, it is possible to form a light emitting layer having an arbitrary laminated structure. However, the deposition method has production problems such as low utilization efficiency of the material and difficulty in increasing the area. In the wet method, there are production advantages such as high utilization efficiency of materials and easy enlargement, but there is a problem that it is difficult to form a laminated structure. When laminated by a wet method, the underlayer should be insoluble in the upper layer solvent. Therefore, the range of material selection is narrow, and there is a problem that the excited state formed in the light emitting layer transfers energy to the peripheral layer to be deactivated and the light emission efficiency is lowered. An object of the present invention is to provide a highly efficient white organic LED that can be formed by a wet process.

Although Patent Document 1 describes that the hole transport layer contains a yellow dopant, it does not clearly show how the yellow dopant is distributed in the hole transport layer, so that it is considered that the light emission efficiency is low.

The features of the present invention for solving the above problems are as follows. The present invention relates to a first electrode, a second electrode, a light emitting layer disposed between the first electrode and the second electrode, and a charge disposed at a position adjacent to the light emitting layer. An organic light emitting device having a transport layer, wherein the charge transport layer adjacent to the light emitting layer contains a light emitting dopant, and the light emitting dopant moves near the interface between the light emitting layer and the charge transport layer It is characterized by having a functional group.

According to the present invention, it is possible to provide an organic light emitting element which can be formed by a wet method and which achieves high efficiency light emission. Problems, configurations, and effects other than those described above will be apparent from the description of the embodiments below.

It is sectional drawing in one Embodiment of the organic light emitting element in this invention.

Hereinafter, the present invention will be described in detail with reference to the drawings and the like.

FIG. 1 is a cross-sectional view of an embodiment of the organic light emitting device in the present invention.

The substrate 1 is a glass substrate. However, the present invention is not limited to the glass substrate, and a plastic substrate or a metal substrate provided with a suitable water permeability lowering protective film can also be used. Moreover, you may have a light extraction layer. As the light extraction layer, a layer having a scattering property or a layer having a microlens can be used.

The lower electrode 2 is an anode. Transparent electrodes such as ITO and IZO are used. However, the invention is not limited thereto, and a laminate of Al, Ag or the like, a combination of Mo, Cr, a transparent electrode and a light diffusion layer, or the like can also be used. Further, the lower electrode is not limited to the anode, and a cathode can also be used. In that case, Al, Mo, a laminate of Al and Li, an alloy such as AlNi, or the like is used. In addition, a transparent electrode such as ITO or IZO may be used.

The upper electrode 8 is a cathode. A laminate of Al, an electron injecting LiF, a fluoride of an alkali metal such as Li20, an oxide or the like is used. In addition, a co-evaporation product of Al and an alkali metal is also used. Alternatively, a laminate of a transparent electrode such as ITO or IZO and an electron injecting electrode such as MgAg or Li can be used. However, it is not limited to them, and MgAg or Ag thin film can be used alone. In addition, when ITO and IZO are formed by sputtering, a buffer layer may be provided in order to reduce damage due to sputtering. For the buffer layer, a metal oxide such as molybdenum oxide or vanadium oxide is used. When the lower electrode is a cathode as described above, the upper electrode is an anode. In that case, a transparent electrode such as ITO or IZO is used. In addition, a metal thin film such as an Ag thin film can be used. When forming a transparent electrode of ITO, IZO or the like by a sputtering method, a buffer layer may be provided in order to reduce damage caused by sputtering. For the buffer layer, a metal oxide such as molybdenum oxide or vanadium oxide is used.

The hole injection layer 3 is a layer for injecting holes from the lower electrode 2. A single layer or a plurality of layers may be provided. The hole injection layer 3 is preferably a conductive polymer such as PEDOT (poly (3,4-ethylenedioxythiophene)): PSS (polystyrene sulfonate). Besides, polypyrrole-based and triphenylamine-based polymer materials can be used. Further, phthalocyanine compounds and starburst amine compounds which are often used in combination with a low molecular weight (weight average molecular weight of 10000 or less) material system are also applicable.

The hole transport layer 4 is a layer that efficiently injects holes from the hole injection layer 3 into the light emitting layer and transfers energy from the light emitting layer to efficiently emit light. As the hole transport layer, materials insoluble in the solvent of the upper layer of a homopolymer or copolymer such as fluorene, carbazole, or arylamine are used. As the copolymer, materials having a thiophene type or a pyrrole type as a skeleton can also be used. Further, polymers having a skeleton such as fluorene, carbazole, arylamine, thiophene or pyrrole in the side chain can also be used. Moreover, it is not limited to the polymer, and among the starburst amine compounds, arylamine compounds, stilbene derivatives, hydrazone derivatives, thiophene derivatives, etc., materials insoluble in the upper layer solvent can be used. Also, polymers containing the above materials may be used. Further, the present invention is not limited to these materials, and two or more of these materials may be used in combination. The hole transport layer 4 of the present invention contains a light emitting dopant. The light emitting dopant of the present invention may be any of so-called fluorescent materials, phosphorescent materials, and delayed fluorescent materials. The light emitting dopant includes the functionality to be present in high concentration near the interface with the light emitting layer. The concentration of the light emitting dopant is not particularly limited, but preferably about 0.1 to 10 wt%.

The light emitting layer 5 is a layer for obtaining light emission of a desired light emission color. The light emitting layer 5 contains a host and a light emitting dopant. As the light emitting dopant, any of so-called fluorescent materials, phosphorescent materials and delayed fluorescent materials can be used. Only one kind of light emitting dopant may be used, but two or three kinds of light emitting dopants may be used. When white light is emitted by mixing two or three types, the light emitting layer 5 may contain a hole transporting material or an electron transporting material in addition to the host and the light emitting dopant. They are used to improve charge balance in the light emitting layer. In addition, the light emitting layer 5 may contain a binder polymer.

It is preferable to use a triphenylamine derivative, a carbazole derivative, a fluorene derivative or an arylsilane derivative as a host. In addition, metal complexes of 8-quinolinol can also be used. Further, binder polymers such as polycarbonate, polystyrene, acrylic resin, polyamide and gelatin can also be used in combination.

The hole blocking layer 6 is a layer for preventing transfer of holes from the light emitting layer 5 to the electron transporting layer 7. Examples of the material of the hole blocking layer 6 include bis (2-methyl-8-quinolinolato) -4- (phenylphenolato) aluminum (hereinafter, BAlq) and tris (8-quinolinolato) aluminum (hereinafter, Alq3). Tris (2,4,6-trimethyl-3- (pyridin-3-yl) phenyl) borane (hereinafter, 3TPYMB), 1,4-bis (triphenylsilyl) benzene (hereinafter, UGH2), oxadiazole derivative, triazole Derivatives, fullerene derivatives, phenanthroline derivatives, quinoline derivatives, benzimidazole derivatives, triazine derivatives and the like can be used.

The electron transport layer 7 is a layer for transporting electrons to the light emitting layer 5 via the hole blocking layer 6. Examples of the material of the electron transport layer 7 include bis (2-methyl-8-quinolinolato) -4- (phenylphenolato) aluminum (hereinafter, BAlq), tris (8-quinolinolato) aluminum (hereinafter, Alq3), Tris (2,4,6-trimethyl-3- (pyridin-3-yl) phenyl) borane (hereinafter, 3TPYMB), 1,4-bis (triphenylsilyl) benzene (hereinafter, UGH2), oxadiazole derivative, triazole derivative A fullerene derivative, a phenanthroline derivative, a quinoline derivative, a benzimidazole derivative, a triazine derivative or the like can be used.

In the structure of the present invention, a large amount of light emitting dopant is distributed in the vicinity of the interface between the hole transport layer 4 and the light emitting layer 5. Therefore, when the excited state formed in the light emitting layer 5 transfers energy to the hole transport layer 4, a large amount of light is emitted in the vicinity of the interface with the light emitting layer 5 of the hole transport layer 4, and the transferred energy is deactivated. Prevent being lost. Further, the light emitting dopant concentration in the hole transport layer 4 is hardly present on the hole injection layer 3 side, and is high near the light emitting layer 5. The light emitting dopant can be a hole trap in the hole transport layer 4, but in the present invention, since it has the concentration distribution as described above, it does not become a hole trap up to the vicinity of the light emitting layer 5. Therefore, hole injection can be efficiently performed as compared with the case where the above concentration distribution is not provided.

In the above description, although the example in which the hole transport layer 4 contains the light emitting dopant is described, the hole blocking layer 6 has the light emitting dopant having a functional group to be present in the vicinity of the interface with the light emitting layer 5 in high concentration. You may Such a structure can also obtain the same effect as described above.
<Relationship Between Light-Emitting Layer 5, Hole-Transporting Layer 4, and Electron-Transporting Layer 7>
In the present invention, it is an essential requirement that at least one of the hole transport layer 4 and the electron transport layer 7 be light emitting dopant in the vicinity of the boundary with the light emitting layer 5. In order to realize that, it is effective that at least one of the hole transport layer 4 or the electron transport layer 7 contains a light emitting dopant having a predetermined functional group. However, there are various forms as to how many kinds of light emitting dopants are included in each of the light emitting layer 5, the hole transporting layer 4, and the electron transporting layer 7. The form is shown in Table 1.

Table 1 shows an example in which a stacked structure is formed in the order of blue, red and green from the upper electrode 8 to the lower electrode 2. Here, although blue, red and green are used, it is possible to realize white light emission not only in this but also in the order of blue, green and red or in the order of red, blue and green. However, the luminous efficiency is particularly high in the order of blue, green, red, blue, red and green.

In the pattern 1, the electron transport layer 7 does not contain a light emitting dopant, the light emitting layer 5 contains a blue dopant and a red dopant, and the hole transport layer 4 contains a green dopant. At this time, the green dopant has a functional group for moving the green dopant to the vicinity of the interface between the light emitting layer 5 and the hole transport layer 4. Specifically, fluoroalkyl group, perfluoroalkyl group and siloxy group having fluoroalkyl group can be mentioned as the functional group.

In the pattern 2, the electron transport layer 7 contains a blue dopant, the light emitting layer 5 contains a red dopant and a green dopant, and the hole transport layer 4 does not contain a luminescent dopant. At this time, the blue dopant has a functional group for moving the blue dopant to the vicinity of the interface between the electron transport layer 7 and the light emitting layer 5. Specifically, an alkyl group having 4 or more carbon atoms, a hydroxy group, a carboxyl group, an amido group, an acyl group and an amino group can be mentioned as the functional group.

The pattern 3 has a configuration in which the electron transport layer 7 contains a blue dopant and a red dopant, the light emitting layer 5 contains a green dopant, and the hole transport layer 4 does not contain a luminescent dopant. At this time, the blue dopant or the red dopant has a functional group for moving the dopant to the vicinity of the interface between the electron transport layer 7 and the light emitting layer 5. Specifically, an alkyl group having 4 or more carbon atoms, a hydroxy group, a carboxyl group, an amido group, an acyl group and an amino group can be mentioned as the functional group. Note that both the blue dopant and the red dopant may move to the vicinity of the interface between the electron transport layer 7 and the light emitting layer 5.

In the pattern 4, the electron transport layer 7 does not contain a light emitting dopant, the light emitting layer 5 contains a blue dopant, and the hole transport layer 4 contains a red dopant and a green dopant. At this time, the red dopant or the green dopant has a functional group for moving the dopant to the vicinity of the interface between the light emitting layer 5 and the hole transport layer 4. Specifically, fluoroalkyl group, perfluoroalkyl group and siloxy group having fluoroalkyl group can be mentioned as the functional group. Note that both the red dopant and the green dopant may move to the vicinity of the interface between the light emitting layer 5 and the hole transport layer 4.

In the pattern 5, the electron transport layer 7 contains a blue light emitting dopant, the light emitting layer 5 contains a red dopant, and the hole transport layer 4 contains a green dopant. At this time, the green dopant has a functional group for moving the green dopant to the vicinity of the interface between the light emitting layer 5 and the hole transport layer 4. Specifically, fluoroalkyl group, perfluoroalkyl group and siloxy group having fluoroalkyl group can be mentioned as the functional group. The blue dopant has a functional group for moving the blue dopant to the vicinity of the interface between the electron transport layer 7 and the light emitting layer 5. Specifically, an alkyl group having 4 or more carbon atoms, a hydroxy group, a carboxyl group, an amido group, an acyl group and an amino group can be mentioned as the functional group.

The luminous efficiency is higher if the luminous dopants of each color are present with a concentration gradient than the luminous dopants contained in the organic luminous element are collectively present in a certain region. Therefore, in the case of the pattern 5, the luminous efficiency is the highest.

Although not shown in Table 1, in the case of pattern 1, not only the hole transport layer 4 but also the light emitting layer 5 may contain a green dopant. The effect of the present invention can be obtained even if there is a color dopant overlapping between the hole transport layer 4 and the electron transport layer 7 and the light emitting layer 5 including other patterns.
Example 1 and Comparative Example 1
In Example 1, the following materials were used for each layer.

A glass substrate was used as the substrate 1 and ITO was used as the lower electrode 2. For the hole injection layer 3, PEDOT (poly (3,4-ethylenedioxythiophene)): PSS (polystyrene sulfonate) was used. For the hole transport layer 4, a triphenylamine-based polymer and a green light emitting dopant represented by the following formula (1) were used. The dopant of Formula (1) has a fluoroalkyl group. As a result, the dopant of the formula (1) spontaneously moves toward the interface between the light emitting layer 5 and the hole transport layer 4, and as a result, the concentration of the green dopant at the interface between the light emitting layer 5 and the hole transport layer 4 It gets higher locally.

As a host of the light emitting layer 5, mCP (1, 3-dicarbazolylbenzene) was used. Moreover, the blue dopant of the following formula (2) and the red dopant of Formula (3) were used for the dopant.

In the light emitting layer 5, the blue dopant and the green dopant are 1% by weight with respect to the host. The coating liquid for forming the light emitting layer 5 was prepared using toluene as a solvent so that the weight ratio of solid content to the solvent was 1%. The light emitting layer 5 was formed by spin coating using this coating solution.

For the hole blocking layer 6, 3TPYMB was used. For the electron transport layer 7, Alq3 was used.
A laminated structure of LiF / Al was used for the upper electrode 8.

In Comparative Example 1, an organic light emitting device was produced as a structure similar to that of Example 1 except for the following points.

The hole transport layer 4 does not have a light emitting dopant. Only the triphenylamine-based polymer of Example 1 is used. Further, the light emitting layer 5 has a green light emitting dopant represented by the following formula (4).

A voltage was applied to the organic light emitting devices manufactured in Example 1 and Comparative Example 1, and the current and luminance flowing were measured. The maximum power efficiency of the organic light emitting device of Example 1 determined from the result was 1.4 times that of the organic light emitting device of Comparative Example 1.

Thus, the power efficiency of the organic light emitting device of Example 1 is increased compared to the organic light emitting device of Comparative Example 1 because the blue dopant and the red dopant are excited in the light emitting layer 5 of Example 1. Thereafter, the excitation energy of the blue dopant transferred to the hole transport layer 4 contributes to the light emission of the green dopant in the hole transport layer 4, and the green dopant efficiently emits light.

Further, in the organic light emitting element of Example 1, since the concentration of the green dopant locally increases at the interface between the light emitting layer 5 and the hole transporting layer 4, the blue dopant and the red dopant of the light emitting layer 5 and the hole transporting layer 4 As a result, the distance between the green dopant and the green dopant is shortened, and energy transfer is likely to occur.
Example 2 and Comparative Example 2
The structure of the organic light emitting device of Example 2 is the same as that of Example 1 except for the following. The hole transport layer 4 does not have a light emitting dopant. Only the triphenylamine-based polymer of Example 1 is used. The host material of the light emitting layer 5 used the material represented by Formula (5).

Further, for the green dopant present in the light emitting layer 5, the light emitting dopant represented by the formula (1) was used.

Further, as the red dopant present in the light emitting layer 5, a light emitting dopant represented by the formula (6) was used.

Further, the hole blocking layer 6 was not used. The electron transport layer 7 is composed of a host and a light emitting dopant, and the material represented by the formula (7) is used as the host, and the material represented by the formula (8) is used as the light emitting dopant. The concentration of the light emitting dopant is 3 wt% with respect to the host. An isopropyl alcohol was used as the solvent, and a solution having a total solid content of 1 wt% was used to form a film on the light emitting layer by spin coating.

The structure of the organic light emitting device of Comparative Example 2 is the same as that of Example 2 except for the following. The electron transport layer 7 does not contain a light emitting dopant. It is only the host material represented by Formula (7).

The light emitting layer 5 contains 3 wt% of the light emitting dopant represented by the formula (8) with respect to the host. A voltage was applied to the organic light emitting device produced in Example 2 and Comparative Example 2, and the current and luminance flowing were measured. As a result, the maximum power efficiency of Example 2 was 1.4 times that of Comparative Example 2.

Thus, the efficiency of the organic light emitting device of Example 2 is large compared to the organic light emitting device of Comparative Example 2 because the exciton formed at the interface between the light emitting layer 5 and the electron transporting layer 7 of Example 2 emits light. This is to contribute to the emission of the green dopant and the red dopant in the layer and to contribute to the emission of the blue dopant without moving to the electron transport layer 7 and quenching.
Example 3
The organic light emitting device of Example 3 has the same configuration as the organic light emitting device of Example 1 except for the following. The dopant represented by Formula (4) was used for the hole transport layer 4 of a present Example. Unlike the formula (1), the dopant of the formula (4) does not have a fluoroalkyl group.

The characteristics of the organic light emitting device of this example were measured in the same manner as in Example 1. As a result, the maximum power efficiency of the organic light emitting device of this example was 1.2 times that of Comparative Example 1.

Thus, the efficiency of the organic light emitting device of Example 3 is large compared to the organic light emitting device of Comparative Example 1 because the blue dopant and the red dopant become excited in the light emitting layer 5 of Example 3, and thereafter This is because the excitation energy of the blue dopant transferred to the hole transport layer 4 contributes to the emission of the green dopant in the hole transport layer 4 and the green dopant efficiently emits light.

On the other hand, the reason that the efficiency of the organic light emitting device of Example 3 is small compared to the organic light emitting device of Example 1 is that the green dopant of Example 3 does not have a fluoroalkyl group. It is distributed throughout, and as a result, the green dopant acts as a hole trap in the hole transport layer 4 to prevent the hole transport.
Example 4 and Comparative Example 3
The organic light-emitting device of Example 4 has the same configuration as that of Example 1 except for the following. For the hole transport layer 4, a light emitting dopant represented by the formula (9) was used.

In addition, as a host material of the hole transport layer 4, a carbazole-based material which is crosslinked by heating to be insolubilized was used. This material contains an acid generator to initiate a crosslinking reaction upon heating. The hole transport layer 4 was formed into a film by spin coating from a toluene solution having a solid content of 1 wt%, and was heated at 180 ° C. for 30 minutes to be crosslinked and inactivated.

The organic light emitting device of Comparative Example 3 has the same configuration as the organic light emitting device of Example 4 except for the following. That is, the material represented by Formula (1) was used as a light emitting dopant of the hole transport layer 4. As a result, the maximum power efficiency of the organic light emitting device of Example 4 was 1.6 times that of the organic light emitting device of Comparative Example 3.

This is because in Comparative Example 3, the light emitting dopant in the hole transport layer 4 is partially decomposed by H + ions generated from the acid generating material, and the light emission intensity is reduced. In Example 4, H + generated from the acid generating material This is because ions are added to the unpaired electron of the N atom of the amide bond contained in the light emitting dopant represented by the formula (9) to prevent the decomposition of the light emitting dopant.

Thus, when the light emitting dopant contains an element having an unpaired electron, the light emission efficiency is improved. In particular, it is preferable to have an unpaired electron at a site away from a conjugated system which contributes to light emission. This is because even if the generated H + is added to the unpaired electron at a site away from the conjugated system, the acid generator does not affect the light emission characteristics.

Table 2 shows the configurations of Example 1-4 and Comparative example 1-3.

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... lower electrode, 3 ... hole injection layer, 4 ... hole transport layer, 5 ... light emitting layer, 6 ... hole blocking layer, 7 ... electron transport layer, 8 ... top electrode,

Claims (18)

A first electrode,
A second electrode,
A light emitting layer disposed between the first electrode and the second electrode;
An organic light emitting device having a charge transport layer disposed at a position adjacent to the light emitting layer;
The charge transport layer adjacent to the light emitting layer contains a light emitting dopant,
The organic light emitting device, wherein the light emitting dopant has a functional group for moving to the vicinity of an interface between the light emitting layer and the charge transport layer. An organic light emitting device according to claim 1, wherein
The organic light emitting device, wherein the charge transport layer is a hole transport layer. An organic light emitting device according to claim 1, wherein
An organic light emitting device characterized in that the charge transport layer is an electron transport layer. The organic light emitting device according to claim 2,
The functional group of the said light emission dopant is either of the following substituents, The organic light emitting element characterized by the above-mentioned.
Functional group: fluoroalkyl group, perfluoroalkyl group, siloxy group having fluoroalkyl group. The organic light emitting device according to claim 3,
The functional group of the said light emission dopant is either of the following substituents, The organic light emitting element characterized by the above-mentioned.
Functional group: an alkyl group having 4 or more carbon atoms, a hydroxy group, a carboxyl group, an amido group, an acyl group, an amino group. The organic light emitting device according to any one of claims 1 to 5, wherein
The organic light emitting device, wherein the light emitting dopant contains an element having an unpaired electron. A material for a hole transport layer used in the organic light emitting device according to claim 2, wherein
A material for a hole transport layer comprising a light emitting dopant having a functional group for moving to the vicinity of the interface between the light emitting layer and the hole transport layer. A material for an electron transport layer used in the organic light emitting device according to claim 3,
What is claimed is: 1. A material for an electron transport layer, comprising a light emitting dopant having a functional group for moving to the vicinity of the interface between the light emitting layer and the electron transport layer. A material for a hole transport layer according to claim 7, wherein
The material for a hole transport layer, wherein the functional group of the light emitting dopant is any of the following substituents.
Functional group: fluoroalkyl group, perfluoroalkyl group, siloxy group having fluoroalkyl group. A material for an electron transport layer according to claim 8, wherein
The functional group of the light emitting dopant is any one of the following substituents:
Functional group: an alkyl group having 4 or more carbon atoms, a hydroxy group, a carboxyl group, an amido group, an acyl group, an amino group. A material for a hole transport layer according to claim 7 or 9,
The material for a hole transport layer, wherein the light emitting dopant contains an element having an unpaired electron. A material for an electron transport layer according to claim 8 or 10, wherein
The material for an electron transport layer, wherein the light emitting dopant contains an element having an unpaired electron. A first electrode,
A second electrode,
A light emitting layer disposed between the first electrode and the second electrode;
An organic light emitting device having a charge transport layer disposed at a position adjacent to the light emitting layer;
The charge transport layer adjacent to the light emitting layer contains a light emitting dopant,
An organic light emitting device characterized in that the concentration of the light emitting dopant in the charge transport layer is locally high in the vicinity of the interface between the light emitting layer and the charge transport layer. The organic light emitting device according to claim 13, wherein
The organic light emitting device, wherein the charge transport layer is a hole transport layer. The organic light emitting device according to claim 13, wherein
An organic light emitting device characterized in that the charge transport layer is an electron transport layer. The organic light emitting device according to claim 14, wherein
The functional group of the said light emission dopant is either of the following substituents, The organic light emitting element characterized by the above-mentioned.
Functional group: fluoroalkyl group, perfluoroalkyl group, siloxy group having fluoroalkyl group. The organic light emitting device according to claim 15, wherein
The functional group of the said light emission dopant is either of the following substituents, The organic light emitting element characterized by the above-mentioned.
Functional group: an alkyl group having 4 or more carbon atoms, a hydroxy group, a carboxyl group, an amido group, an acyl group, an amino group. An organic light emitting device according to any one of claims 13 to 17, wherein
The organic light emitting device, wherein the light emitting dopant contains an element having an unpaired electron.

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