Boron-nitrogen organic heterocyclic compound and application thereof

Abstract

The invention provides a boron-nitrogen organic heterocyclic compound and application thereof. The boron-nitrogen organic heterocyclic compound has a structure as shown in a formula I or a formula II. The structure of the boron-nitrogen organic heterocyclic compound is designed, the obtained boron-nitrogen organic heterocyclic compound has excellent performance, and an organic electroluminescent device prepared by using the boron-nitrogen organic heterocyclic compound as a luminescent layer material has relatively low driving voltage and relatively high current efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic optoelectronic display, and particularly relates to a boron-nitrogen-containing organic heterocyclic compound and its application. Background Art

[0002] An organic light emitting diode (OLED) is a display component that utilizes the phenomenon of self-luminescence. It has a large viewing angle. Compared with liquid crystal display components, OLED components are thinner, lighter, have a faster response speed, and can achieve flexible display. Therefore, its application as a full-color display component or lighting device is highly anticipated.

[0003] Generally, the organic light emitting phenomenon refers to the phenomenon of converting electrical energy into light energy using organic substances. An organic light emitting diode that utilizes the organic light emitting phenomenon usually has a structure including an anode, a cathode, and an organic layer sandwiched between the anode and the cathode.

[0004] Among them, in order to improve the efficiency and stability of the organic light emitting diode, the organic layer is in most cases composed of a multi-layer structure formed by different substances respectively. For example, it can be composed of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, etc. If a voltage is applied between the two electrodes in the structure of such an organic light emitting diode, holes in the anode will be injected into the organic layer, and electrons in the cathode will also be injected into the organic layer. When the injected holes and electrons meet, excitons are formed. When the excitons release energy and transition to the ground state, photons will be emitted, thus generating light. Such an organic light emitting diode is widely recognized as having characteristics such as self-luminescence, high brightness, high efficiency, low driving voltage, wide viewing angle, high contrast, and high-speed responsiveness.

[0005] Currently, the research on organic electroluminescent materials has been widely carried out in the academic and industrial fields. Among them, the light emitting material is an important part of the organic electroluminescent device. The transport performance and light emitting efficiency of the light emitting material restrict the industrialization of the light emitting device. Therefore, designing and finding a compound as a new type of OLED material to overcome the deficiencies that occur in the actual application process is the focus and future research and development trend in the research work of OLED materials. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a boron-nitrogen-containing organic heterocyclic compound and its application. Through the design of the compound structure containing boron and nitrogen, the obtained boron-nitrogen-containing organic heterocyclic compound has excellent properties and is suitable for use as a light emitting layer material in organic electroluminescent devices.

[0007] To achieve this purpose, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides an organoheterocyclic compound of boron and nitrogen, and the organoheterocyclic compound of boron and nitrogen has a structure shown in Formula I or Formula II:

[0009]

[0010] X is selected from oxygen, sulfur or The wavy line represents the connection site of the group; Ar 1 is a substituted or unsubstituted aryl group of C 6 ~C 30 or a substituted or unsubstituted heteroaryl group of C 3 ~C 30 ;

[0011] In Formula I and Formula II, R 1 , R 2 , R 3 , R 4 are the same as or different from each other, and each independently selected from hydrogen, deuterium, a substituted or unsubstituted alkyl group of C 1 ~C 12 , a substituted or unsubstituted aryl group of C 6 ~C 30 , a substituted or unsubstituted heteroaryl group of C 3 ~C 30 , a substituted or unsubstituted diphenylamino group, a substituted or unsubstituted triphenylsilyl group;

[0012] The substituents in the substituted groups are selected from deuterium, F, CN, an alkyl group of C 1 ~C 12 , an aryl group of C 6 ~C 30 or a heteroaryl group of C 3 ~C 30 ;

[0013] And all hydrogen atoms in Formula I and Formula II can be independently replaced by deuterium, F, CN, an alkyl group of C 1 ~C 12 , an aryl group of C 6 ~C 30 or a heteroaryl group of C 3 ~C 30 .

[0014] Preferably, the alkyl group of C 1 ~C 12 is selected from methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, pivalyl, n-hexyl or cyclohexyl.

[0015] More preferably, the alkyl group of C 1 ~C 12 is selected from methyl, ethyl, isopropyl or tert-butyl.

[0016] Preferably, the C 6 ~C 30 aryl refers to the general name of the monovalent group remaining after removing a hydrogen atom from the aryl carbon of an aromatic hydrocarbon molecule; the C 6 ~C 30 aryl includes monocyclic aryl or fused-ring aryl.

[0017] Preferably, the C 6 ~C 30 aryl is selected from phenyl, biphenyl, terphenyl, naphthyl, anthryl, indenyl, fluorenyl, perylenyl, phenanthryl, pyrenyl, fluoranthenyl, fluorenyl, spirobifluorenyl or benzophenanthryl.

[0018] More preferably, the C 6 ~C 30 aryl is selected from phenyl, biphenyl, naphthyl.

[0019] Preferably, the C 3 ~C 30 heteroaryl refers to the general name of the group obtained by replacing one or more aryl carbons in the aryl with heteroatoms; the heteroatoms of the C 3 ~C 30 heteroaryl are selected from oxygen, sulfur, nitrogen or silicon; the C 3 ~C 30 heteroaryl includes monocyclic heteroaryl or fused-ring heteroaryl.

[0020] Preferably, the C 3 ~C 30 heteroaryl is selected from pyridyl, benzofuranyl, benzothiophenyl, dibenzofuranyl, dibenzothiophenyl, carbazolyl, benzofurocarbazolyl, benzofurothiophenyl or triazinyl.

[0021] More preferably, the C 3 ~C 30 heteroaryl is selected from pyridyl, dibenzofuranyl, dibenzothiophenyl or carbazolyl.

[0022] Further preferably, R 1 、R 2 、R 3 、R 4 are the same as or different from each other and are each independently selected from hydrogen, deuterium, F, cyano, methyl, trifluoromethyl, tert-butyl, biphenyl, terphenyl, pyridyl, carbazolyl, wherein R is hydrogen or an alkyl group having 1 to 5 carbon atoms, and the wavy line represents the connection site of the group.

[0023] Preferably, X is oxygen, sulfur, The wavy line represents the connection site of the group.

[0024] Preferably, the boron-nitrogen-containing organic heterocyclic compound is selected from any one of Compounds 1 to 88:

[0025]

[0026]

[0027]

[0028]

[0029] The present invention lists some specific structural forms of the boron-nitrogen-containing organic heterocyclic compound, but the boron-nitrogen-containing organic heterocyclic compound described in the present invention is not limited to these listed chemical structures. Any structure based on the structures shown in Formula I or Formula II, where R 1 , R 2 , R 3 , R 4 , and X meet the above-defined conditions should be included.

[0030] In a second aspect, the present invention provides an organic electroluminescent device, which includes the boron-nitrogen-containing organic heterocyclic compound as described in the first aspect.

[0031] Preferably, the organic electroluminescent device includes a first electrode, a second electrode, and an organic layer disposed between the first electrode and the second electrode, and the material of the organic layer includes the boron-nitrogen-containing organic heterocyclic compound as described in the first aspect.

[0032] Preferably, the organic layer includes a light-emitting layer, and the material of the light-emitting layer includes the boron-nitrogen-containing organic heterocyclic compound as described in the first aspect.

[0033] Furthermore, the light-emitting layer is prepared by a vapor deposition method.

[0034] In a third aspect, the present invention provides a display device, which includes the organic electroluminescent device as described in the second aspect.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] By designing the structure of the boron-nitrogen-containing organic heterocyclic compound, the obtained boron-nitrogen-containing organic heterocyclic compound has good light-emitting properties and can be used to prepare an organic electroluminescent device. Especially as the material of the light-emitting layer in the organic electroluminescent device, it can effectively reduce the driving voltage of the organic electroluminescent device and improve the current efficiency of the organic electroluminescent device. Specific Embodiments

[0037] For the convenience of understanding the present invention, the present invention lists the preparation examples and embodiments as follows. It should be understood by those skilled in the art that the preparation examples and embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0038] Synthesis Example 1

[0039] This embodiment provides a method for synthesizing compound 1, and the synthesis method is as follows:

[0040]

[0041] (1) Synthesis of intermediate 1-1

[0042] Under nitrogen protection, into a 500mL three-necked flask, add 200mL dry toluene, 0.1mol halide-1, 0.1mol iminobibenzyl, 0.001mol Pd(dba)2 (bis(dibenzylideneacetonepalladium), 4g of 10% tri-tert-butylphosphine toluene solution (the amount of tri-tert-butylphosphine is 0.002mol) and 0.3mol sodium tert-butoxide, heat to reflux reaction for 12h, cool to room temperature, add water to separate, then wash the organic layer with water until neutral, dry with magnesium sulfate, filter to remove magnesium sulfate, concentrate to dryness, and crystallize with ethanol to obtain intermediate 1-1;

[0043] The mass spectrometry of intermediate 1-1 revealed a mass-to-charge ratio (m / z) of 397.1.

[0044] (2) Synthesis of Compound 1

[0045] Under nitrogen protection, the reaction bottle containing 0.01 mol of intermediate 1-1 and 100 ml of toluene was cooled to 0 ° C, and then 0.3 mol of 1.7M tert-butyl lithium pentane solution (35 ml) was added to the reaction system. After the addition was completed, the temperature was raised to 50 ° C and stirred for 3 hours. Then the system was cooled to -40 ° C, 0.012 mol of boron tribromide was slowly added, and after the addition was completed, the temperature was raised to 25 ° C and stirred for 4 hours. When the reaction was completed, the temperature was lowered to -40 ° C, 30 ml of methanol was slowly added to quench the reaction, and then the temperature was raised to 0 ° C, and 50 ml of saturated Na 2 S 2 O 3 After the addition was complete, the organic layer was washed with water until neutral, dried over magnesium sulfate, filtered to remove the magnesium sulfate, concentrated to dryness, and separated by silica gel column chromatography with n-heptane: dichloromethane volume ratio = 10:1 to obtain compound 1.

[0046] The obtained compound 1 was subjected to mass spectrometry detection, and the mass-to-charge ratio (m / z) was measured to be 371.1.

[0047] Synthesis Example 2

[0048] This example provides a method for synthesizing Compound 2, and the synthesis method is as follows:

[0049]

[0050] (1) Synthesis of Intermediate 2-1

[0051] Referring to the synthesis method of Synthesis Example 1, replace iminodibenzyl in Synthesis Example 1 with 5H-dibenzo[b,f]azepine-10,11-dione, and Intermediate 2-1 can be obtained under the same other conditions.

[0052] The obtained Intermediate 3-2 was subjected to mass spectrometry detection, and the measured mass-to-charge ratio (m / z) was 425.1.

[0053] (2) Synthesis of Intermediate 2-2

[0054] Under nitrogen protection, into a 2000 mL three-necked flask, add 300 mL of dry dichloromethane and cool to -40 °C, then slowly dropwise add a dichloromethane solution of titanium tetrachloride with a concentration of 1 mol / L (382 mL, containing 0.382 mol of titanium tetrachloride). After the addition is complete, cool to -50 °C, and then quickly dropwise add 191 mL of a toluene solution of dimethylzinc with a concentration of 2 mol / L (containing 0.382 mol of dimethylzinc). After the addition is complete, keep the obtained viscous red suspension stirred vigorously at -50 °C to -40 °C for 10 min, and then quickly dropwise add a toluene solution of 0.016 mol of Intermediate 2-1 (0.016 mol of Intermediate 2-1 is dissolved in 200 mL of dichloromethane). During the addition process, keep the temperature between -50 °C and -40 °C. After the addition is complete, keep the temperature between -45 °C and -35 °C for heat preservation and stirring for 2 h, and then slowly raise the temperature to between -10 °C and -5 °C for heat preservation and stirring for 2 h. Then pour the reaction solution into an ice-water mixture to quench the reaction. After liquid separation, the obtained organic phase is washed five times with saturated brine (300 mL each time), dried and passed through a silica gel column. After the obtained column eluate is concentrated to dryness, column chromatography is carried out with a volume ratio of n-heptane:dichloromethane = 20:1 to obtain Intermediate 2-2;

[0055] The obtained Intermediate 2-2 was subjected to mass spectrometry detection, and the measured mass-to-charge ratio (m / z) was 453.2.

[0056] (3) Synthesis of Compound 2

[0057] Referring to the synthesis method of Synthesis Example 1, replace Intermediate 1-1 in Synthesis Example 1 with Intermediate 2-2, and Compound 2 can be obtained under the same other conditions.

[0058] Compound 2 was detected by mass spectrometry, and the measured mass-to-charge ratio (m / z) was 427.2.

[0059] Synthesis Example 3

[0060] This example provides a method for synthesizing Compound 3, and the synthesis method is as follows:

[0061]

[0062] Referring to the synthesis method of Synthesis Example 1, substituting Halide-2 for Halide-1 in Synthesis Example 1, and keeping other conditions unchanged, Compound 3 can be obtained.

[0063] Compound 3 was detected by mass spectrometry, and the measured mass-to-charge ratio (m / z): 387.1.

[0064] Synthesis Example 4

[0065] This synthesis example provides a method for synthesizing Compound 4, and the synthesis method is as follows:

[0066]

[0067] Referring to the synthesis method of Synthesis Example 2, substituting Halide-2 for Halide-1 in Synthesis Example 2, and keeping other conditions unchanged, Compound 4 can be obtained.

[0068] Compound 4 was detected by mass spectrometry, and the measured mass-to-charge ratio (m / z): 443.2.

[0069] Synthesis Example 5

[0070] This synthesis example provides a method for synthesizing Compound 5, and the synthesis method is as follows:

[0071]

[0072] Referring to the synthesis method of Synthesis Example 1, substituting Halide-3 for Halide-1 in Synthesis Example 1, and keeping other conditions unchanged, Compound 5 can be obtained.

[0073] Compound 5 was detected by mass spectrometry, and the measured mass-to-charge ratio (m / z): 446.2.

[0074] Referring to the synthesis methods of the above compounds and combining with common organic synthesis means, Compounds 19, 20, 23, 24, 25, 27, 28, 29, 30, 35, 36, 37, 39, 40, 41, 47, 49, 51, 62, 63, 64, 71, 79, 80, 87 were prepared and detected by mass spectrometry, and the test results are shown in Table 1 below.

[0075] Table 1

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

[0082] Other compounds for which the specific synthesis steps are not listed can be prepared by combining the above examples with common general knowledge in the art.

[0083] The specific structures of the compounds used in the following device examples and device comparative examples are shown below:

[0084]

[0085] In the following device examples, the boron and nitrogen-containing compound provided by the present invention is selected as the luminescent layer doping material in the organic electroluminescent device, and in the device comparative examples, the above BD-1, BD-2, BD-3, and BD-4 are selected as the luminescent layer doping materials in the organic electroluminescent device.

[0086] Device Example 1

[0087] This device example provides an organic electroluminescent device, using Compound 1 provided by Synthesis Example 1 of the present invention as the luminescent layer doping material; and in this example, the luminescent layer is prepared by evaporation.

[0088] The structure of the organic electroluminescent device is:

[0089] ITO / HT(40nm) / BH-1: Compound 1 (3%) (30nm) / ET(30nm) / LiF(0.5nm) / Al(150nm).

[0090] The preparation method of the above organic electroluminescent device is as follows:

[0091] The glass substrate coated with the ITO transparent conductive layer (as the anode) is ultrasonically treated in a cleaning agent, then rinsed in deionized water, ultrasonically degreased in a mixed solvent of acetone and ethanol, baked in a clean environment until completely dehydrated, cleaned with ultraviolet light and ozone, and bombarded with a low-energy cation beam on the surface to improve the surface properties and enhance the bonding ability with the hole injection layer;

[0092] Place the above glass substrate in a vacuum chamber, evacuate to 1×10-5 ~9×10 -6 Pa, HT was vacuum-evaporated on the anode as the hole transport layer at a deposition rate of 0.1 nm / s, and the deposited film thickness was 40 nm;

[0093] The light-emitting layer was vacuum-evaporated on the hole transport layer at a deposition rate of 0.1 nm / s, and the total deposited film thickness was 30 nm. The host material of the light-emitting layer was BH-1, and the doping material was Compound 1 provided by the present invention. 3% refers to the doping ratio of the doping material, that is, the volume ratio of the host material to the doping material in the light-emitting layer is 97:3.

[0094] ET was vacuum-evaporated on the light-emitting layer as the electron transport layer of the device at a deposition rate of 0.1 nm / s, and the total deposited film thickness was 30 nm;

[0095] 0.5 nm of LiF and 150 nm of Al were vacuum-evaporated on the electron transport layer as the electron injection layer and the cathode.

[0096] The brightness, driving voltage, and current efficiency of the fabricated organic light-emitting device were measured.

[0097] Device Examples 2 to 30

[0098] Device Examples 2 to 19 each provide an organic light-emitting device, which is different from Device Example 1 only in that the doping material of the light-emitting layer is different (see Table 2 for details), and other conditions are the same as those in Device Example 1.

[0099] Device Comparative Examples 1 to 3

[0100] Device Comparative Examples 1 to 3 each provide an organic light-emitting device, which is different from Device Example 1 only in that the doping material of the light-emitting layer is different (see Table 2 for details), and other conditions are the same as those in Device Example 1.

[0101] Performance Test

[0102] The driving voltage, current efficiency, and lifetime LT90 of the above-provided OLED devices were tested; among them, LT90 refers to the time required for the brightness to drop to 90% of the original brightness while keeping the current density unchanged when the initial brightness is 1000 nit. The test items include the brightness, driving voltage, and current efficiency of the organic light-emitting device. The data of the driving voltage, current efficiency, and LT90 are all relative values at a brightness of 1000 cd / m 2 (based on the test data of Device Comparative Example 2). The performance test results of the organic light-emitting device are shown in Table 2 below.

[0103] Table 2

[0104]

[0105]

[0106] As can be seen from the above, through structural design, the present invention obtains a compound suitable as a doping material for the light-emitting layer. The organic electroluminescent device prepared therefrom has a lower driving voltage, a higher current efficiency, and a longer service life.

[0107] Device Examples 20 - 30

[0108] Device Examples 20 - 30 respectively provide an organic electroluminescent device, which is only different from Device Example 1 in that the host material of the light-emitting layer is selected as BH-2 and the doping materials are different (see Table 3 for details), and other conditions are the same as those in Device Example 1.

[0109] Device Comparative Examples 4 - 5

[0110] Device Comparative Examples 4 - 5 respectively provide an organic electroluminescent device, which is only different from Device Example 1 in that the host material of the light-emitting layer is BH-2 and the doping materials are different (see Table 3 for details), and other conditions are the same as those in Device Example 1.

[0111] Performance Test

[0112] Test the driving voltage, current efficiency, and lifetime LT90 of the above-provided OLED devices; among them, LT90 refers to the time required for the current density to remain unchanged while maintaining the initial brightness of 1000 nit and the brightness drops to 90% of the original brightness. The test items include the brightness, driving voltage, and current efficiency of the organic electroluminescent device. The data of the driving voltage, current efficiency, and LT90 are all relative values at a brightness of 1000 cd / m 2 at (benchmarked by the test data of Device Comparative Example 5). The performance test results of the organic electroluminescent device are shown in Table 3 below.

[0113] Table 3

[0114] Device Comparative Example 4 BD-3 1000 0.94 0.78 1 Device Comparative Example 5 BD-4 1000 1 1 1 Device Example 20 Compound 5 1000 0.88 1.27 1.29 Device Example 21 Compound 23 1000 0.90 1.36 1.45 Device Example 22 Compound 24 1000 0.85 1.39 1.51 Device Example 23 Compound 29 1000 0.79 1.41 1.56 Device Example 24 Compound 30 1000 0.78 1.38 1.49 Device Example 25 Compound 41 1000 0.77 1.36 1.46 Device Example 26 Compound 62 1000 0.74 1.35 1.47 Device Example 27 Compound 63 1000 0.80 1.41 1.49 Device Example 28 Compound 64 1000 0.88 1.44 1.51 Device Example 29 Compound 79 1000 0.81 1.39 1.52 Device Example 30 Compound 80 1000 0.82 1.327 1.51

[0115] As can be seen from the above, through structural design, the present invention obtains a compound suitable as a doping material for the light-emitting layer. The organic electroluminescent device prepared therefrom has a lower driving voltage, a higher current efficiency, and a longer service life.

[0116] The present invention uses the above examples to illustrate the boron-nitrogen-containing organic heterocyclic compounds of the present invention and their applications. However, the present invention is not limited to the above examples, that is, it does not mean that the present invention must rely on the above examples to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific formulas, etc., all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A boron-nitrogen organic heterocyclic compound, characterized in that: The boron-nitrogen organic heterocyclic compound has a structure as shown in Formula I or Formula II: X is selected from oxygen, sulfur or The wavy line represents the attachment site of the group; Ar1 ​​is a substituted or unsubstituted C6~C 30 Aryl, substituted or unsubstituted C3~C 30 heteroaryl; In Formula I and Formula II, R1, R2, R3, and R4 are the same or different from each other, and are independently selected from hydrogen, deuterium, substituted or unsubstituted C1 to C 12 Alkyl, substituted or unsubstituted C6~C 30 Aryl, substituted or unsubstituted C3~C 30 a heteroaryl group, a substituted or unsubstituted diphenylamino group, or a substituted or unsubstituted triphenylsilyl group; The substituents in the substituted groups are selected from deuterium, F, CN, C1-C 12 Alkyl, C6~C 30 Aryl or C3~C 30 heteroaryl; All hydrogen atoms in Formula I and Formula II can be independently replaced by deuterium, F, CN, C1-C 12 Alkyl, C6~C 30 Aryl or C3~C 30 is substituted with a heteroaryl group.

2. The boron-nitrogen organic heterocyclic compound according to claim 1, characterized in that: C1~C 12 The alkyl group is selected from methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, tert-pentyl, n-hexyl or cyclohexyl.

3. The boron-nitrogen organic heterocyclic compound according to claim 1, characterized in that: C6~C 30 The aryl group of is selected from phenyl, biphenyl, terphenyl, naphthyl, anthracenyl, indenyl, fluorenyl, perylenyl, phenanthryl, pyrenyl, fluoranthenyl, fluorenyl, spirobifluorenyl or triphenylenyl.

4. The boron-nitrogen organic heterocyclic compound according to claim 1, characterized in that: C3~C 30 The heteroatoms in the heteroaryl group are selected from oxygen, sulfur, nitrogen or silicon; Preferably, the C3 to C 30 The heteroaromatic group is selected from benzofuranyl, benzothiophenyl, dibenzofuranyl, dibenzothiophenyl, carbazolyl, benzofuranocarbazolyl, benzofuranothiophenyl or triazine.

5. The boron-nitrogen organic heterocyclic compound according to claim 1, characterized in that: R1, R2, R3, and R4 are the same or different from each other and are each independently selected from hydrogen, deuterium, F, cyano, methyl, trifluoromethyl, tert-butyl, biphenyl, terphenyl, pyridyl, carbazolyl, Where R is hydrogen or a C1-C5 alkyl group, and the wavy line represents the attachment site of the group; Preferably, X is oxygen, sulfur, The wavy line represents the attachment site of the group.

6. The boron-nitrogen organic heterocyclic compound according to any one of claims 1 to 5, characterized in that: The boron-nitrogen organic heterocyclic compound is selected from any one of compounds 1 to 88:

7. An organic electroluminescent device, characterized in that: The organic electroluminescent device comprises the boron-nitrogen organic heterocyclic compound according to any one of claims 1 to 6.

8. The organic electroluminescent device according to claim 7, characterized in that: The organic electroluminescent device comprises a first electrode, a second electrode and an organic layer disposed between the first electrode and the second electrode; the organic layer comprises a light-emitting layer; the light-emitting layer comprises the boron-nitrogen organic heterocyclic compound as claimed in any one of claims 1 to 6.

9. The organic electroluminescent device according to claim 8, characterized in that: The light-emitting layer is prepared by evaporation method.

10. A display device, characterized in that: The display device comprises the organic electroluminescent device according to any one of claims 7 to 9.

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