CN109256474B - Organic electroluminescent device and display device - Google Patents

Organic electroluminescent device and display device Download PDF

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CN109256474B
CN109256474B CN201811022561.6A CN201811022561A CN109256474B CN 109256474 B CN109256474 B CN 109256474B CN 201811022561 A CN201811022561 A CN 201811022561A CN 109256474 B CN109256474 B CN 109256474B
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CN109256474A (en
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李国孟
魏金贝
李梦真
李维维
何麟
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Yungu Guan Technology Co Ltd
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    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
    • H10K50/12—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers comprising dopants
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    • H10K50/00—Organic light-emitting devices
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    • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
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    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
    • H10K50/12—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers comprising dopants
    • H10K50/121—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers comprising dopants for assisting energy transfer, e.g. sensitization
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Abstract

The invention provides an organic electroluminescent device and a display device. The organic electroluminescent device includes a light emitting layer and a hole blocking layer, wherein: the material of the light-emitting layer includes a host material; the material constituting the hole blocking layer is the same as the host material. According to the organic electroluminescent device provided by the invention, the same material is used as the main material of the light-emitting layer and the hole blocking layer, so that the energy level barrier between the main body of the light-emitting layer and the hole blocking layer in the OLED device can be effectively reduced, the turn-on voltage of the device is reduced, the light-emitting efficiency is improved, and the service life of the device is prolonged.

Description

Organic electroluminescent device and display device
Technical Field
The invention belongs to the technical field of display, and particularly relates to an organic electroluminescent device and a display device.
Background
The organic electroluminescent device is a device in which a light emitting layer is disposed between an electron transport layer and a hole transport layer, and further a cathode and an anode are disposed at the outer side thereof, electrons and holes are injected into the device by an external voltage and are recombined at the light emitting layer to form excitons, and photons are emitted outward through a fluorescence or phosphorescence process and are deactivated. The organic light-emitting diode has the characteristics of all solid state, self luminescence, wide viewing angle, high response speed, low driving voltage, low energy consumption and the like, so the organic light-emitting diode has huge application prospect in the fields of display and illumination.
In recent years, a new generation of Thermally Activated Delayed Fluorescence (TADF) material is widely used in a light emitting material of an organic electroluminescent device, and the TADF material can simultaneously utilize singlet excitons having a generation probability of 25% and triplet excitons having a generation probability of 75% to obtain high light emitting efficiency. FIG. 1 is a schematic diagram of the TADF molecular electroluminescent process, as shown in FIG. 1, due to its singlet state (S)1) And triplet state (T)1) Energy level difference (Δ E)ST) Smaller, triplet excitons may passReverse intersystem crossing (RISC) returns to a singlet state to form singlet excitons for subsequent radiative emission, thereby improving the radiative emission efficiency of the excitons.
However, when a TADF material is used for the light-emitting layer of an organic electroluminescent device, the device may have low light-emitting efficiency and a short lifetime.
Disclosure of Invention
In view of the above-mentioned defects in the prior art, the present invention provides an organic electroluminescent device, which can improve the light-emitting efficiency of the organic electroluminescent device and prolong the lifetime of the organic electroluminescent device.
The invention also provides a display device which has good performance due to the organic electroluminescent device.
In order to achieve the above object, the present invention provides an organic electroluminescent device comprising a light-emitting layer and a hole blocking layer, wherein: the material of the light-emitting layer includes a host material; the material constituting the hole blocking layer is the same as the host material.
The invention adopts the main material of the luminescent layer as the hole blocking layer, can effectively intercept excitons from diffusing to the hole blocking layer adjacent to the luminescent layer, thereby improving the luminous efficiency and the service life of the organic electroluminescent device.
Meanwhile, the same material is used for the main material of the light-emitting layer and the hole blocking layer, so that the energy level barrier between the light-emitting layer and the hole blocking layer in the organic electroluminescent device can be effectively reduced, the starting voltage of the organic electroluminescent device is reduced, and the light-emitting efficiency is improved.
In addition, as the main body material of the light-emitting layer generally has better transmission performance, the main body material is used as a hole blocking layer, so that the phenomenon that the composite area of the device is too narrow due to poor material mobility can be avoided, and the service life of the device is not influenced.
The invention also provides a display device comprising the organic electroluminescent device. The display device has the same advantages as the organic electroluminescent device compared with the prior art, and the description is omitted here.
According to the organic electroluminescent device provided by the invention, the main material of the light-emitting layer and the material of the hole blocking layer are made of the same material, so that the energy level barrier between the main material of the light-emitting layer and the hole blocking layer can be effectively reduced, the turn-on voltage of the device is reduced, and the light-emitting efficiency is improved; meanwhile, as the triplet state energy level of the main material of the light-emitting layer is higher, the light-emitting layer can be used as a hole blocking layer, exciton diffusion can be effectively intercepted, and the light-emitting efficiency and the service life of the device are further improved.
In addition, as the main material of the luminescent layer and the material of the hole blocking layer are made of the same material, the fine metal mask evaporation operation of the luminescent layer and the hole blocking layer can be completed in the same chamber during actual production, so that a vacuum evaporation chamber can be omitted compared with the conventional process, and the production efficiency of the device is improved.
The display device provided by the invention also has good performance due to the organic electroluminescent device.
Drawings
FIG. 1 is a schematic diagram of the electroluminesence process of TADF molecule;
FIG. 2 is a schematic structural diagram of an organic electroluminescent device according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of an organic electroluminescent device according to another embodiment of the present invention;
FIG. 4 is a schematic diagram illustrating the energy transfer principle of the electroluminescence process according to an embodiment of the present invention.
Detailed Description
The organic electroluminescent device provided by the embodiment comprises a light-emitting layer and a hole blocking layer, wherein: the material of the light-emitting layer includes a host material; the material constituting the hole blocking layer is the same as the host material.
As shown in fig. 2 and 3, an organic electroluminescent device (OLED device) generally includes an anode, a Hole Transport Layer (HTL), an emission layer (EML), an Electron Transport Layer (ETL), and a cathode, which are sequentially disposed. Wherein, a Hole Injection Layer (HIL) can be further arranged between the anode and the hole transmission layer, and an Electron Injection Layer (EIL) can be further arranged between the cathode and the electron transmission layer. A Hole Blocking Layer (HBL) is disposed between the light emitting layer and the electron transport layer.
The materials of the light-emitting layer generally include a host material and a guest material, or include a host material, a sensitizer, and a guest material. As host material for the light-emitting layer, it should generally satisfy the following requirements: 1) has a triplet energy level higher than that of the guest material to effectively prevent energy from being reversed from the guest material to the host material, resulting in energy loss; 2) the material has good transmission performance, namely, the material has higher charge and energy transfer rate, so that the charge is effectively transferred; 3) the capability of balancing electron and hole transport is possessed; 4) has stable performance.
In this embodiment, since the triplet energy level of the host material is higher, especially higher than that of the guest material, the host material of the light-emitting layer is used as the hole-blocking layer in this embodiment, which can effectively block excitons from diffusing to the hole-blocking layer adjacent to the light-emitting layer, thereby improving the light-emitting efficiency and the lifetime of the organic electroluminescent device.
Meanwhile, the same material is used for the main material of the light-emitting layer and the hole blocking layer, so that the energy level barrier between the light-emitting layer and the hole blocking layer in the organic electroluminescent device can be effectively reduced, the starting voltage of the organic electroluminescent device is reduced, and the light-emitting efficiency is improved.
In addition, as the host material of the light-emitting layer generally has better transmission performance, the host material is used as the hole blocking layer, so that the phenomenon that the recombination region of the device is too narrow due to poor material mobility can be avoided, and the service life of the device is not influenced.
With further reference to fig. 2, the materials of the light emitting layer specifically include a Host material (Host) and a guest material, wherein the guest material includes at least one thermally activated delayed fluorescence material (TADF Emitter). One or more TADF materials are adopted as object materials of the luminous layer, or are called as thermal activation delayed fluorescent dyes, so that the generation of energy level barriers and exciplexes can be effectively avoided, the turn-on voltage of the organic electroluminescent device is reduced, the luminous efficiency of the device is improved, and the service life of the device is prolonged.
Or further referring to fig. 3, the material of the light emitting layer specifically includes a Host material (Host), a sensitizer and a guest material, wherein the sensitizer is TADF material, and the guest material is a conventional fluorescent dye and/or a conventional phosphorescent dye. Taking a conventional Fluorescent dye (Fluorescent dyes) as an example of a guest material, the light emitting principle can refer to fig. 4, in the organic electroluminescent device, energy of a host material is transferred to a sensitizer (i.e., a TADF material), then triplet energy of the TADF material returns to a singlet state through a reverse intersystem crossing (RISC) process, and further energy is transferred to the conventional Fluorescent dye, so that complete energy transfer from the host material to the guest material molecule can be realized, and particularly, the Fluorescent doped dye can break through 25% of internal quantum efficiency limit, and further improve the light emitting efficiency of the device.
Specifically, the triplet energy level of the host material of the light emitting layer should be greater than the triplet energy level of the thermally activated delayed fluorescence material, so as to achieve effective transfer of energy between the host material and the TADF material. In the specific implementation process, the molecular structure of the used main material contains at least one group of carbazolyl, anilino, aromatic ring, pyrimidyl, triazinyl, silane group, phosphorus oxygen group and the like.
Preferably, the host material may be selected from organic compounds represented by the following numbers TDH1 to TDH24, in particular, to ensure better luminous efficiency and longer lifetime of the organic electroluminescent device.
Figure BDA0001787332530000041
Figure BDA0001787332530000051
At present, TADF materials are used in the light-emitting layer of an organic electroluminescent device, and the device often has low light-emitting efficiency and short lifetime. One of the main causes for this is exciton diffusion in the light-emitting layer. Due to the fact that energy level difference between the singlet state and the triplet state of the TADF material is relatively small, the triplet state exciton energy level of the light emitting layer of the TADF material is high, excitons are easy to generate to diffuse to other functional layers and collide with current carriers of other functional layers to be annihilated, and finally the light emitting efficiency of the organic electroluminescent device is low, and the service life of the device is influenced. In order to reduce the barrier from the triplet level to the singlet level, the TADF materials with lower singlet-triplet level difference tend to be selected, which further affects the light emitting efficiency and lifetime of the device.
According to the technical scheme of the embodiment, the same material is used for the main material and the hole blocking layer of the light-emitting layer, so that exciton diffusion to the hole blocking layer adjacent to the light-emitting layer can be effectively blocked, and the light-emitting efficiency and the service life of the organic electroluminescent device are improved.
It is understood that the technical solution of the present embodiment has a good effect on the thermally activated delayed fluorescent material with a small singlet-triplet energy level difference. Therefore, the thermally activated delayed fluorescence material used in the embodiment may be a thermally activated delayed fluorescence material commonly used in a light emitting layer in an OLED device at present, and is preferably a thermally activated delayed fluorescence material having a singlet-triplet level difference of less than 0.3 eV.
In the specific implementation, the thermally activated delayed fluorescence material used is preferably a compound represented by the following numbers T-1 to T-99.
Figure BDA0001787332530000061
Figure BDA0001787332530000071
Figure BDA0001787332530000081
Figure BDA0001787332530000091
Figure BDA0001787332530000101
Figure BDA0001787332530000111
T-71(n represents 1, 2 or 3) T-72(n represents 1, 2 or 3) T-73(n represents 1, 2 or 3)
Figure BDA0001787332530000112
Figure BDA0001787332530000121
In the present invention, the term "conventional fluorescent dye" refers to other fluorescent materials besides TADF materials, which can be used as dyes for the light emitting layer of the OLED device. In one embodiment, conventional fluorescent dyes are selected to include, but are not limited to, the following compounds designated by numbers F-1 to F-24.
Figure BDA0001787332530000131
Figure BDA0001787332530000141
In the present invention, the "conventional phosphorescent dye" refers to a phosphorescent material currently used as a dye for a light emitting layer of an OLED device, and is not particularly limited.
Specifically, in the case of TADF material as the guest material of the light-emitting layer, the doping concentration of the guest material (i.e., the mass ratio of the thermally activated delayed fluorescence component to the material of the light-emitting layer) is generally controlled to be 0.1 to 50 wt%; preferably, the doping concentration of the TADF material is greater than 5 wt% and less than or equal to 50 wt%, to ensure that the organic electroluminescent device has good luminous efficiency and long lifetime.
Specifically, in the case where TADF material is used as a sensitizer for the light-emitting layer, and a conventional fluorescent dye and/or a conventional phosphorescent dye is used as a guest material, the doping concentration of the sensitizer is generally controlled to be 0.1 to 50 wt%, and the doping concentration of the guest material is generally controlled to be 0.1 to 50 wt%. Preferably, the doping concentration of the sensitizer is 5 to 50 wt% and the doping concentration of the guest material is 0.1 to 30 wt%, so as to ensure good luminous efficiency and long lifetime of the organic electroluminescent device.
Specifically, in the above organic electroluminescent device, the thickness of the light-emitting layer is generally controlled to be 1 to 200 nm. Preferably, in order to further control the recombination region of the light-emitting layer and ensure the light-emitting efficiency and the service life of the organic electroluminescent device, the thickness of the light-emitting layer is generally 1 to 50 nm.
The thickness of the hole-blocking layer is generally 1 to 200 nm. Preferably, the thickness of the hole blocking layer is generally 1 to 50nm in order to further improve the luminous efficiency and lifetime of the organic electroluminescent device.
The embodiment also provides a display device comprising the organic electroluminescent device.
The display device can be specifically a display device such as an OLED display, and any product or component with a display function including the display device, such as a television, a digital camera, a mobile phone, a tablet computer, and the like. The display device has the same advantages as the organic electroluminescent device compared with the prior art, and the description is omitted here.
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Examples 1 to 8
Examples 1 to 8 each provide an organic electroluminescent device having a device structure including an ITO anode, a Hole Injection Layer (HIL), a Hole Transport Layer (HTL), an emission layer (EML), a Hole Blocking Layer (HBL), an Electron Transport Layer (ETL), an Electron Injection Layer (EIL), and a cathode in this order, as shown in fig. 2.
The hole injection layer is made of HATCN, and the total thickness is generally 5-30nm, and in this embodiment 10 nm. The hole transport layer is made of a material commonly used in the HTL of the OLED, in this embodiment NPB, and has a total thickness of generally 5-500nm, in this embodiment 40 nm. The Host material (Host) of the luminescent layer is consistent with the material of the hole blocking layer, the object material is TADF material (TADF Emitter), and the doping concentration is 0.1-50 wt%; the thickness of the light-emitting layer is generally 1 to 200nm, and 30nm in this embodiment. The thickness of the hole-blocking layer is generally 1 to 200nm, and 5nm in this embodiment. The material of the electron transport layer is a common material for an ETL layer in an OLED, in this embodiment, TPBI, with a thickness of 5-300nm, in this embodiment, 30 nm. The electron injection layer and the cathode material are selected from LiF (1nm) and metallic aluminum (200 nm).
The compound NPB is N, N '-diphenyl-N, N' - (1-naphthyl) -1,1 '-biphenyl-4, 4' -diamine, and is named as N, N '-Bis- (1-naphthyl) -N, N' -Bis-phenyl- (1,1'-biphenyl) -4,4' -diamine in English. TPBI is 1,3,5-Tris (1-phenyl-1H-benzimidazol-2-yl) benzene, having the name 1,3,5-Tris (1-phenyl-1H-benzimidazol-2-yl) bezene. The chemical structural formulas of the two are as follows:
Figure BDA0001787332530000161
specific selection and doping concentrations of materials for the light emitting layer and the hole blocking layer in the organic electroluminescent devices provided in examples 1 to 8, and test results of the corresponding organic electroluminescent devices are shown in table 1.
As can be seen from the test results of table 1, the OLED device has relatively high luminous efficiency and lifetime when the host material of the light emitting layer is identical to the hole blocking layer material. And, as the doping concentration of the TADF material in the light-emitting layer changes, the light-emitting efficiency and lifetime of the OLED device also change, and the OLED device has relatively optimal light-emitting efficiency and lifetime under the condition that the doping concentration of the TADF material is greater than 5 wt% and less than or equal to 50 wt%, especially the doping concentration is 10 wt% to 50 wt%. In particular, when the doping concentration of the TADF material is 30 wt% (example 2), the OLED device is 1000cd/m2The current efficiency at luminance is 17.7cd/A, the lifetime LT50 is 57h, and the performance is best.
Therefore, according to the technical scheme provided by this embodiment, when the host material of the light-emitting layer is the same as the hole blocking layer material, and the light-emitting layer adopts the TADF material as the guest material, the OLED device has very high light-emitting efficiency and lifetime; moreover, the OLED device performance can be better by adjusting the doping concentration of the TADF material.
TABLE 1
Figure BDA0001787332530000171
Comparative example 1
This comparative example provides an organic electroluminescent device having a structure in accordance with examples 1 to 8, with particular reference to FIG. 2; the parameters of the respective functional layers are substantially the same as those of example 2, except that the materials used for the hole-blocking layer are different. The selection of materials in the specific light-emitting layer and hole blocking layer and the test results for the corresponding OLED devices are shown in table 1.
As can be seen from the comparison of table 1, when the host material of the light-emitting layer is different from the material used for the hole-blocking layer, even if the TADF material in the light-emitting layer is at the optimum doping concentration (i.e., 30 wt%), the current efficiency and lifetime of the OLED device in comparative example 1 are significantly lower than those of the OLED devices in example 2 and other examples, which further confirms that: when the main material of the light-emitting layer is consistent with the material used by the hole blocking layer, the light-emitting efficiency and the service life of the OLED device are obviously improved.
Comparative example 2
This comparative example provides an organic electroluminescent device having a structure in accordance with examples 1 to 8, with particular reference to FIG. 2; the parameters of the respective functional layers correspond substantially to those of example 2, with the only difference that: the host material and the hole-blocking layer of the light-emitting layer both used a compound (No. TDH25) having the following structure. The selection of materials in the particular light-emitting layer and hole blocking layer and the test results for the corresponding OLED devices are shown in table 1.
Figure BDA0001787332530000181
From the comparison results in table 1, it can be seen that the host materials in comparative example 2 are not selected from the compounds numbered TDH1 to TDH24, and the luminous efficiency and lifetime of the OLED device are improved compared to those in comparative example 1, but are still significantly lower than those of the OLED devices in examples 1 to 8.
Examples 9 to 14
Examples 9 to 14 each provide an organic electroluminescent device having a device structure including an ITO anode, a Hole Injection Layer (HIL), a Hole Transport Layer (HTL), an emission layer (EML), a Hole Blocking Layer (HBL), an Electron Transport Layer (ETL), an Electron Injection Layer (EIL), and a cathode in this order, as shown in fig. 3. The Host material (Host) of the light-emitting layer is the same as the material of the hole blocking layer, and TADF material is used as a sensitizer of the light-emitting layer, and conventional fluorescent dye is used as a guest material (i.e. fluorochenties) of the light-emitting layer. The materials and thicknesses of the other functional layers were the same as those of examples 1 to 8, and the thickness of the light-emitting layer was 30nm and the thickness of the hole-blocking layer was 5 nm.
The material selection, doping concentration and performance test results of the OLED devices in the corresponding examples, for specific light-emitting layers and hole blocking layers are shown in table 2.
TABLE 2
Figure BDA0001787332530000182
As can be seen from the test results of table 2 above, the OLED device has very high luminous efficiency and lifetime when the host material of the light emitting layer is identical to the material of the hole blocking layer. Moreover, by adjusting the doping concentration of the sensitizer and/or guest material in the light-emitting layer, the light-emitting efficiency and lifetime of the corresponding OLED device are also changed. The OLED device has relatively optimal light emitting efficiency and lifetime under the condition that the doping concentration of the TADF material is greater than 5 wt%, particularly 10 wt% to 50 wt%, and the doping concentration of the conventional fluorescent dye is 0.1 wt% to 30 wt%, particularly 0.1 wt% to 20 wt%.
Especially when the TADF material is in the luminescent layerThe doping concentration of the OLED device is 30 wt%, and the doping concentration of the conventional fluorescent dye is 5 wt% (example 10), the OLED device is in the range of 5000cd/m2The current efficiency at the luminance is 77.7cd/A, the lifetime LT50 is 776h, and the performance is the best.
Therefore, according to the technical scheme provided by the embodiment, when the host material of the light-emitting layer is the same as the hole blocking layer material, and the light-emitting layer adopts the TADF material as the sensitizer and the conventional fluorescent dye as the dye, the OLED device has very high light-emitting efficiency and long service life; moreover, the OLED device performance can be better by adjusting the doping concentrations of the TADF material and the traditional fluorescent dye.
Comparative example 3
This comparative example provides an organic electroluminescent device having a device structure in accordance with examples 9 to 14, with particular reference to FIG. 3; the parameters of the respective functional layers also correspond substantially to those of examples 9 to 14, except that the host material of the light-emitting layer does not correspond to the material used for the hole-blocking layer or the doping concentration does not correspond. The selection of specific materials and the test results of the corresponding organic electroluminescent devices are shown in table 2.
As can be seen from the comparison of table 2, when the host material of the light-emitting layer is different from the material used for the hole-blocking layer, even if the sensitizer and the dye in the light-emitting layer are both at the optimum doping concentrations (30 wt% and 5 wt%, respectively), the current efficiency and lifetime of the OLED device in comparative example 3 are much lower than those of the OLED devices in example 10 and other examples, and it is further confirmed that: when the main material of the light-emitting layer is consistent with the material used by the hole blocking layer, the light-emitting efficiency and the service life of the OLED device are obviously improved.
Examples 15 to 18
Examples 15 to 18 each provide an organic electroluminescent device having a device structure in accordance with examples 1 to 8, and specifically refer to fig. 2. The materials and thicknesses of the functional layers of the OLED devices in examples 15-18 are substantially the same as those in example 2, except for the thickness of the hole blocking layer. Wherein the hole blocking layers of examples 15-18 have thicknesses of 1nm, 10nm, 50nm and 100nm, respectively, the performance test results of the corresponding OLED devices are shown in table 3.
TABLE 3
Figure BDA0001787332530000201
As can be seen from table 3, when the host material of the light emitting layer is identical to the material of the hole blocking layer, the light emitting efficiency and the lifetime of the organic electroluminescent device are changed as the thickness of the hole blocking layer is changed. From the test results of examples 15 to 18 and the foregoing examples 1 to 14, it can be seen that the light emitting efficiency and lifetime of the OLED device are higher under the condition that the hole blocking layer has a thickness of 1 to 50nm, and especially under the condition that the hole blocking layer has a thickness of 5nm, the light emitting efficiency and lifetime of the OLED device are more remarkably exhibited.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (3)

1. An organic electroluminescent device comprising a light-emitting layer and a hole-blocking layer, wherein: the material of the light-emitting layer includes a host material represented by TDH 6; the material constituting the hole blocking layer is the same as the host material; the thickness of the hole blocking layer is 1-50 nm;
the material of the light-emitting layer comprises a guest material with the doping concentration of more than 5 wt% and less than or equal to 50 wt%, and the guest material comprises at least one thermal activation delayed fluorescence material represented by T-8;
or the like, or, alternatively,
the material of the light-emitting layer comprises a sensitizer represented by T-8 with the doping concentration of 5-50 wt% and a guest material represented by F-8 with the doping concentration of 0.1-30 wt%;
Figure FDF0000011817240000011
2. the organic electroluminescent device according to claim 1, wherein the thickness of the light-emitting layer is 1 to 200 nm.
3. A display device comprising the organic electroluminescent element according to any one of claims 1 to 2.
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