Oxazolobenzocarbazole compound, organic electroluminescent device and display device

Abstract

The invention provides an oxazolobenzocarbazole compound, an organic electroluminescent device and a display device, and relates to the technical field of organic electroluminescent materials. The oxazolobenzocarbazole compound disclosed by the invention has a proper energy level and good electron mobility, and can be used as an electron transport material to effectively reduce the potential barrier of electron transport and effectively block the diffusion of holes to one side of an electron transport layer, so that the luminous efficiency of a device can be further improved, the driving voltage can be reduced, and the service life can be prolonged.

Description

Technical Field

[0001] The invention belongs to the field of organic photoelectric technology, and specifically relates to an oxazolobenzocarbazole compound, an organic electroluminescent device and a display device. Background Art

[0002] OLED (Organic Light Emitting Diode) is a new type of display technology with the advantages of self-luminescence, high contrast, wide viewing angle, and fast response. The development of OLED technology stems from the improvement and breakthrough of traditional liquid crystal display technology. Its characteristic is that it uses organic thin film as the light-emitting material and emits light through the flow of current under the action of an electric field.

[0003] The background of OLED display technology can be traced back to the 1960s, when scientists began to study the application of organic compounds in the optoelectronic field. However, it was not until 1987 that Japanese scientist Kyoto Takato first reported the experimental results based on OLED, and OLED technology really attracted people's attention. In the past few decades, OLED technology has made significant breakthroughs and progress in light-emitting materials, display device structure, and drive circuit design. These breakthroughs have not only improved the brightness, color reproduction and life of OLED display technology, but also greatly promoted the application of OLED in various fields.

[0004] As OLED products gradually enter the market, people have higher and higher requirements for the performance of such products. The current OLED materials and device structures cannot completely solve the problems of OLED product efficiency, lifespan, cost, etc. There are problems such as low luminous efficiency, high driving voltage and short service life.

[0005] Therefore, the field urgently needs to study more types of OLED materials so that when they are used in OLED devices, they can further improve the luminous efficiency, reduce the driving voltage, and extend the service life. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention aims to provide an oxazolobenzocarbazole compound, an organic electroluminescent device and a display device. When the compound is used in an organic electroluminescent device, the device can have higher luminous efficiency, lower driving voltage and longer service life.

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

[0008] In a first aspect, the present invention provides an oxazolobenzocarbazole compound, wherein the oxazolobenzocarbazole compound has a structure as shown in Formula I:

[0009]

[0010] In Formula I:

[0011] R1, R2, and R3 are each independently selected from substituted or unsubstituted C6 to C 30 Aryl, substituted or unsubstituted C3~C 30 Aromatic heterocyclic group;

[0012] X1-X3 are each independently selected from N or CH, and at least one of X1-X3 is N, for example, one, two or three of X1-X3 are N;

[0013] L1 is independently selected from a single bond, a substituted or unsubstituted C6-C 30 Arylene, substituted or unsubstituted C3~C 30 Aromatic heteroaryl;

[0014] In R1, R2, R3, and L1, the substituted substituents are each independently selected from phenyl, biphenyl, terphenyl, naphthyl, anthracenyl, indenyl, fluorenyl, perylenyl, phenanthryl, pyrenyl, fluoranthenyl, naphthoxybiphenyl, benzofuranyl, benzothiophenyl, dibenzofuranyl, dibenzothiophenyl, carbazolyl, benzofuranocarbazolyl, or benzofuranothiophenyl;

[0015] n is an integer selected from 0-1.

[0016] Preferably, the C6~C 30 Aryl is selected from phenyl, biphenyl, terphenyl, naphthyl, anthracenyl, indenyl, fluorenyl, perylenyl, phenanthrenyl, pyrenyl, fluoranthenyl or naphthoxybiphenyl.

[0017] Preferably, the C6~C 30 The arylene group is selected from phenylene, biphenylene, terphenylene, naphthylene, anthracene, indenylene, fluorenylene, perylene, phenanthrenylene, pyrenylene, fluoranthenylene or naphthylene biphenylene.

[0018] Preferably, the C3 to C 30 Aromatic heterocyclic group, C3~C 30 The heteroatoms in the aromatic heteroarylene group are each independently selected from at least one of an oxygen atom, a sulfur atom, a silicon atom, a boron atom and a nitrogen atom.

[0019] Preferably, the C3 to C 30 The aromatic heterocyclic group is selected from benzofuranyl, benzothiophenyl, dibenzofuranyl, dibenzothiophenyl, carbazolyl, benzofuranocarbazolyl or benzofuranothiophenyl.

[0020] Preferably, the C3 to C 30The aromatic heteroarylene group is selected from benzofuranylene, benzothiophenylene, dibenzofuranylene, dibenzothiophenylene, carbazolylene, benzofuranocarbazolylene or benzofuranothiophenylene.

[0021] Preferably, the oxazolobenzocarbazole compound includes any one of the following compounds:

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029] Preferably, the oxazolobenzocarbazole compound includes any one of the following compounds 1 to 12:

[0030]

[0031] The oxazolobenzocarbazole compounds have suitable energy levels and good electron mobility. As electron transport materials, they can not only effectively reduce the potential barrier of electron transport, but also effectively block the diffusion of holes to one side of the electron transport layer, which can further improve the luminous efficiency of the device, reduce the driving voltage, and extend the service life.

[0032] In a second aspect, the present invention provides an organic electroluminescent device, wherein the organic electroluminescent device comprises the oxazolobenzocarbazole compound.

[0033] Preferably, 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 material of the organic layer comprises the oxazolobenzocarbazole compound as described above.

[0034] Preferably, the organic layer includes an electron transport layer; the material of the electron transport layer includes the oxazolobenzocarbazole compound.

[0035] In a third aspect, the present invention provides a display device, comprising the organic electroluminescent device.

[0036] The oxazolobenzocarbazole compounds have suitable energy levels and good electron mobility. As electron transport materials, they can not only effectively reduce the potential barrier of electron transport, but also effectively block the diffusion of holes to one side of the electron transport layer, which can further improve the luminous efficiency of the device, reduce the driving voltage, and extend the service life.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention designs the structure of oxazolobenzocarbazole compounds to obtain oxazolobenzocarbazole-containing compounds, which have good thermal stability and excellent electron transport performance and can be used to prepare organic electroluminescent devices, especially as electron transport materials in organic electroluminescent devices, and can effectively reduce the driving voltage of organic electroluminescent devices and improve the current efficiency of organic electroluminescent devices. DETAILED DESCRIPTION

[0039] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0040] Synthesis Example 1

[0041] This example provides compound 1 and a synthesis method thereof. The synthesis route of compound 1 is as follows:

[0042]

[0043] (1) Synthesis of Intermediate I

[0044] 100 mmol 6-bromo-2-phenylnaphtho[1,2-d]oxazole, 110 mmol o-nitrobenzene borate, 2 mmol tetrakis(triphenylphosphine)palladium, 120 mmol potassium carbonate, 300 mL toluene, 150 ml ethanol and 150 mL water were added to a reaction bottle, and the mixture was reacted at 90° C. for 6 h under nitrogen protection. After the reaction was complete, 150 ml ethanol was added, the mixture was stirred for 30 min, filtered, 300 ml water was added to the filter cake, the mixture was stirred for 30 min, filtered, 300 ml ethanol was added to the filter cake, the mixture was stirred for 30 min, filtered, and the filter cake was recrystallized from toluene and ethanol to obtain intermediate I.

[0045] The mass spectrum data of intermediate I was tested, and the mass spectrum m / z was measured to be 366.10.

[0046] (2) Synthesis of Intermediate II

[0047] 50mmol of intermediate I, 100mmol of triphenylphosphine and 150mL of o-dichlorobenzene were added to a reaction flask, and the mixture was refluxed for 6h under nitrogen protection. After the reaction was complete, o-dichlorobenzene was distilled off under reduced pressure. 500ml of toluene was added to the residue in the reaction flask, and the mixture was heated to dissolve. The mixture was passed through a silica gel column, and the column liquid was concentrated to 100ml. 300ml of ethanol was added, and the mixture was stirred for 30min. The mixture was filtered, and the filter cake was dried under vacuum to obtain intermediate II.

[0048] The mass spectrum data of intermediate II was tested, and the mass spectrum m / z was measured to be 334.11.

[0049] The NMR data of intermediate II are as follows: 1 H-NMR (Bruker, Switzerland, AvanceⅡ400MHz nuclear magnetic resonance spectrometer, CDCl3), δ8.23~8.17 (m, 3H), δ8.02 (d, 1H), 7.97 (s, 1H), δ7.82 (d, 1H), δ7.65~7.57 (m, 3H), δ7.38 (m, 2), δ7.25~7.18 (m, 2H), 7.15 (d, 1H).

[0050] (3) Synthesis of Compound 1

[0051] 100 mmol of intermediate II, 100 mmol of 2-chloro-4,6-diphenyl-1,3,5-triazine, 150 mmol of potassium carbonate, 50 mmol of cuprous bromide, 20 mmol of o-phenanthroline, 30 mmol of 18-crown ether-6 and 300 mL of dimethyl sulfoxide were added to a reaction bottle, and the mixture was reacted at 155°C for 12 h under nitrogen protection. After the reaction, the reaction solution was cooled to below 50°C, poured into 300 mL of pure water, and 300 mL of toluene was added. The reaction system was quenched with a 10% hydrochloric acid solution until it was neutral, stirred for 10 min, and allowed to stand for stratification. The lower aqueous phase was extracted twice with toluene, the organic phases were combined, washed with water until neutral, the organic phase was concentrated until no solvent flowed out, 160 mL of ethanol was added, stirred for 1 h, and filtered to obtain compound 1.

[0052] The mass spectrometry of compound 1 showed an m / z of 565.19.

[0053] Synthesis Example 2

[0054] This example provides compound 2 and a synthesis method thereof. The synthesis route of compound 2 is as follows:

[0055]

[0056] Synthesis of compound 2

[0057] Compound 2 was obtained by following the synthetic method of compound 1, except that 2-chloro-4,6-diphenyl-1,3,5-triazine was replaced by 2-([1,1'-biphenyl]-4-yl)-4-chloro-6-phenyl-1,3,5-triazine.

[0058] The mass spectrometry of compound 2 showed an m / z of 641.22.

[0059] Synthesis Example 3

[0060] This embodiment provides a method for synthesizing compound 3, and the synthetic route of compound 3 is as follows:

[0061]

[0062] (1) Synthesis of Intermediate III

[0063] According to the synthetic method of intermediate I, except that 6-bromo-2-phenylnaphtho[1,2-d]oxazole is replaced by 6-bromo-2-naphthylnaphtho[1,2-d]oxazole, intermediate III is obtained.

[0064] The mass spectrometry detection of intermediate III showed m / z of 416.12.

[0065] (2) Synthesis of Intermediate IV

[0066] According to the synthetic method of intermediate II, except that intermediate I is replaced by intermediate III, intermediate IV is obtained.

[0067] The mass spectrometry detection of intermediate IV showed m / z of 384.13.

[0068] (3) Synthesis of Compound 3

[0069] According to the synthetic method of compound 1, compound 3 is obtained by replacing intermediate II with intermediate IV.

[0070] The mass spectrometry of compound 3 showed an m / z of 615.21.

[0071] Synthesis Example 4

[0072] This embodiment provides a method for synthesizing compound 4, and the synthetic route of compound 4 is as follows:

[0073]

[0074] (1) Synthesis of intermediate V

[0075] Intermediate V was obtained by following the synthetic method of intermediate I, except that 6-bromo-2-phenylnaphtho[1,2-d]oxazole was replaced by 2-([1,1'-biphenyl]-4-yl)-6-bromonaphtho[1,2-d]oxazole.

[0076] The intermediate V was detected by mass spectrometry, with an m / z of 442.13.

[0077] (2) Synthesis of Intermediate VI

[0078] According to the synthetic method of intermediate II, except that intermediate I is replaced by intermediate V, intermediate VI is obtained.

[0079] The mass spectrometry detection of intermediate VI showed m / z of 410.14.

[0080] (3) Synthesis of Compound 4

[0081] Compound 4 was obtained by following the synthetic method of compound 1, except that intermediate II was replaced by intermediate VI and 2-chloro-4,6-diphenyl-1,3,5-triazine was replaced by 2,4-di([1,1'-biphenyl]-4-yl)-6-chloro-1,3,5-triazine.

[0082] The mass spectrometry of compound 4 showed an m / z of 793.28.

[0083] Other compounds for which specific synthesis steps are not listed can be prepared by common knowledge in the art in combination with the above embodiments.

[0084] The specific structures of the compounds used in the following device examples and device comparative examples are shown below:

[0085]

[0086]

[0087] In the following device examples, the oxazolobenzocarbazole compounds provided by the present invention are selected as electron transport materials in organic electroluminescent devices, and the device comparative examples select the above D-1, D-2 and D-3 as electron transport materials in organic electroluminescent devices.

[0088] Device Example 1

[0089] Device Example 1 provides an organic electroluminescent device, using Compound 1 provided in Synthesis Example 1 of the present invention as an electron transport material.

[0090] The structure of the organic electroluminescent device is:

[0091] ITO / NPB (40 nm) / GH-1: Ir (piq) 33% (35 nm) / Compound 1 (30 nm) / LiF (0.5 nm) / Al (150 nm).

[0092] The preparation method of the organic electroluminescent device is as follows:

[0093] 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 the water is completely removed, cleaned with ultraviolet light and ozone, and bombarded with a low-energy cation beam to improve the properties of the surface and enhance the binding ability with the hole injection layer;

[0094] The glass substrate was placed in a vacuum chamber and evacuated to 1×10 -5 ~9×10 -4 Pa, vacuum evaporate NPB on the anode as a hole transport layer, the evaporation rate is 0.1nm / s, and the evaporation film thickness is 40nm;

[0095] The light-emitting layer material is vacuum-deposited on the hole transport layer. The light-emitting layer material is composed of GH-1 and Ir(piq)3 equivalent to 3% of the mass of GH-1. The evaporation rate is 0.1 nm / s and the total evaporation film thickness is 35 nm.

[0096] Vacuum evaporation of electron transport layer material on the light-emitting layer. The electron transport layer material is compound 1, and the evaporation rate is 0.1 nm / s, and the evaporation film thickness is 30 nm;

[0097] 0.5 nm of LiF and 150 nm of Al were vacuum-deposited on the electron transport layer as the electron injection layer and cathode.

[0098] Device Examples 2 to 12

[0099] Device Examples 2 to 12 respectively provide an organic electroluminescent device, which differs from Device Example 1 only in that the electron transport material is different (see Table 1 below for details), and other conditions are the same as those of Device Example 1.

[0100] Device Comparison Examples 1 to 3

[0101] Device Comparative Examples 1 to 3 respectively provide an organic electroluminescent device, which is different from Device Example 1 only in that the electron transport material is different (see Table 1 below for details), and other conditions are the same as those of Device Example 1.

[0102] Performance Testing

[0103] Test the driving voltage, current efficiency and life LT90 of the OLED devices provided above; LT90 refers to the time required for the brightness to drop to 90% of the original brightness while maintaining the current density at the initial brightness of 1000nit. The test items include the brightness, driving voltage and current efficiency of the organic electroluminescent device. The driving voltage, current efficiency and LT90 data are all based on a brightness of 1000cd / m 2The relative value at the time of the test is based on the test data of the device comparative example 1. The performance test results of the organic electroluminescent device are shown in the following Table 1:

[0104] Table 1

[0105]

[0106] From the content of Table 1, it can be seen that the present invention provides an oxazolobenzocarbazole compound, which can be used as an electron transport material for an OLED light-emitting device, so that the OLED light-emitting device has a lower driving voltage, a higher current efficiency and a longer life.

[0107] The applicant declares that the present invention illustrates the detailed process flow of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. An oxazolobenzocarbazole compound, characterized in that: The o-oxazolobenzocarbazole compound has a structure as shown in Formula I: In Formula I: R1, R2, and R3 are each independently selected from substituted or unsubstituted C6 to C 30 Aryl, substituted or unsubstituted C3~C 30 Aromatic heterocyclic group; X1-X3 are each independently selected from N or CH, and at least one of X1-X3 is N; L1 is independently selected from a single bond, a substituted or unsubstituted C6-C 30 Arylene, substituted or unsubstituted C3~C 30 Aromatic heteroaryl; In R1, R2, R3, and L1, the substituents substituted are each independently selected from phenyl, biphenyl, terphenyl, naphthyl, anthracenyl, indenyl, fluorenyl, perylenyl, phenanthrenyl, pyrenyl, fluoranthenyl, naphthoxybiphenyl, 、 benzofuranyl, benzothiophenyl, dibenzofuranyl, dibenzothiophenyl, carbazolyl, benzofuranocarbazolyl or benzofuranothiophenyl; n is an integer selected from 0-1.

2. The oxazolobenzocarbazole compound according to claim 1, characterized in that: C6~C 30 Aryl is selected from phenyl, biphenyl, terphenyl, naphthyl, anthracenyl, indenyl, fluorenyl, perylenyl, phenanthrenyl, pyrenyl, fluoranthenyl or naphthoxybiphenyl; C6~C 30 The arylene group is selected from phenylene, biphenylene, terphenylene, naphthylene, anthracene, indenylene, fluorenylene, perylene, phenanthrenylene, pyrenylene, fluoranthenylene or naphthylene biphenylene.

3. The oxazolobenzocarbazole compound according to claim 1, characterized in that: C3~C 30 Aromatic heterocyclic group, C3~C 30 The heteroatoms in the aromatic heteroarylene group are each independently selected from at least one of an oxygen atom, a sulfur atom, a silicon atom, a boron atom and a nitrogen atom.

4. The oxazolobenzocarbazole compound according to claim 1, characterized in that: C3~C 30 The aromatic heterocyclic group is selected from benzofuranyl, benzothiophenyl, dibenzofuranyl, dibenzothiophenyl, carbazolyl, benzofuranocarbazolyl or benzofuranothiophenyl; C3~C 30 The aromatic heteroarylene group is selected from benzofuranylene, benzothiophenylene, dibenzofuranylene, dibenzothiophenylene, carbazolylene, benzofuranocarbazolylene or benzofuranothiophenylene.

5. The oxazolobenzocarbazole compound according to claim 1, characterized in that: The oxazolobenzocarbazole compound includes any one of the following compounds:

6. The oxazolobenzocarbazole compound according to claim 1, characterized in that: The oxazolobenzocarbazole compound includes any one of the following compounds 1 to 12:

7. An organic electroluminescent device, characterized in that: The organic electroluminescent device comprises the oxazolobenzocarbazole 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 arranged between the first electrode and the second electrode; the material of the organic layer comprises the oxazolobenzocarbazole compound as described above.

9. The organic electroluminescent device according to claim 8, characterized in that: The organic layer includes an electron transport layer; the material of the electron transport layer includes the oxazolobenzocarbazole compound.

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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