Triazine compounds and organic electroluminescent devices

Abstract

The application provides a triazine compound and an organic electroluminescent device, and relates to the technical field of organic electroluminescent materials.The triazine compound is designed to be used as an electron transport material of an OLED light-emitting device, so that the OLED light-emitting device has a lower driving voltage, a higher current efficiency and a longer service life.

Description

Technical Field

[0001] This invention belongs to the field of organic electroluminescent materials technology, specifically relating to a triazine compound and an organic electroluminescent device. Background Technology

[0002] Organic light-emitting diodes (OLEDs) are devices fabricated by depositing one or more layers of organic material between two metal electrodes via spin coating or vacuum evaporation. A classic three-layer OLED comprises a hole transport layer, an emissive layer, and an electron transport layer. Holes generated by the anode combine with electrons generated by the cathode via the electron transport layer in the emissive layer to form excitons, which then emit light. OLEDs can be tuned to emit various desired light colors by changing the material of the emissive layer.

[0003] Organic light-emitting diodes (OLEDs), as a novel display technology, possess unique advantages such as self-illumination, wide viewing angle, low energy consumption, high efficiency, thinness, rich colors, fast response speed, wide applicable temperature range, low driving voltage, the ability to manufacture flexible, bendable, and transparent display panels, and environmental friendliness. They can be applied to flat panel displays and next-generation lighting, and can also be used as backlights for LCDs.

[0004] Since the late 1980s, organic light-emitting diodes (OLEDs) have been used in industry, such as as screens in cameras and mobile phones. To meet the increasing demands for OLED devices, there is an urgent need to develop a wider variety of materials to improve the performance of OLED devices in terms of current efficiency, lifetime, and other aspects. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a triazine compound and an organic electroluminescent device. By designing the structure of the triazine compound, the present invention enables it to serve as an electron transport material for OLED light-emitting devices, thereby improving the performance of the OLED devices.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a triazine compound having the structure shown in Formula I:

[0008]

[0009] Formula I

[0010] In Formula I, Ar1 and Ar2 are each independently selected from any one of substituted or unsubstituted C6~C20 aryl and substituted or unsubstituted C6~C20 heteroaryl groups;

[0011] In Ar1 and Ar2, the substituents are each independently selected from any one of D, F, cyano, and C1-C6 alkyl groups;

[0012] R1 to R4 are each independently selected from any one of the C1 to C6 alkyl groups;

[0013] In the compound of formula I, each H atom can be independently replaced by a D atom.

[0014] This invention designs the structure of triazine compounds by bridging two triazine rings with biphenyl groups and attaching at least one fluorene group to each of the two triazine rings. The resulting triazine compounds have suitable energy level distribution, excellent film-forming properties and stability, and good charge transport performance. They can be used as electron transport materials for OLED light-emitting devices, enabling OLED light-emitting devices to have lower driving voltage, higher current efficiency and longer lifetime.

[0015] In this invention, "D" represents a deuterium atom. Unless otherwise specified, "H" and "hydrogen" both represent "protium".

[0016] Preferably, the C6-C20 aryl group is selected from phenyl, naphthyl, biphenyl, fluorenyl, triphenylene, fluoranyl, phenanthrene, etc. , Any one of them.

[0017] Preferably, the C6-C20 heteroaryl group is selected from any one of dibenzofuranyl, dibenzothiophenyl, and carbazoleyl.

[0018] Preferably, the C1-C6 alkyl group is selected from any one of methyl, ethyl, propyl, butyl, pentyl, and hexyl.

[0019] In this invention, Ar1 and Ar2 may be the same or different.

[0020] Preferably, Ar1 and Ar2 are each independently selected from phenyl, naphthyl, biphenyl, 9,9-dimethylfluorenyl, , Any one of dibenzofuranyl and dibenzothiophene.

[0021] Preferably, Ar1 and Ar2 are both selected from dibenzofuranyl compounds, which, as electron transport materials, can significantly reduce the driving voltage of devices.

[0022] Preferably, Ar1 and Ar2 are both selected from 9,9-dimethylfluorenyl, which, as an electron transport material, can significantly extend the lifespan of the device.

[0023] Preferably, R1 to R4 are each independently selected from any one of methyl, ethyl, propyl, butyl, pentyl, and hexyl.

[0024] Preferably, R1 to R4 are all selected from methyl groups.

[0025] Preferably, the triazine compound is selected from any one of the following substituted or unsubstituted compounds:

[0026]

[0027]

[0028] ;

[0029] The substitution refers to the replacement of at least one hydrogen atom in the above compound with a deuterium atom.

[0030] Preferably, the triazine compound is selected from any one of the following compounds:

[0031] , , , , , , , .

[0032] In a second aspect, the present invention provides an organic electroluminescent device, the organic electroluminescent device comprising an anode, a cathode, and an organic thin film layer disposed between the anode and the cathode, the organic thin film layer comprising a triazine compound as described in the first aspect.

[0033] Preferably, the organic thin film layer includes an electron transport layer, and the material of the electron transport layer includes the aforementioned triazine compound.

[0034] Preferably, the organic thin film layer further includes a light-emitting layer, the material of which includes a host material and a dopant material.

[0035] In this invention, no special restrictions are placed on the doping material of the light-emitting layer; any doping material known in the art can be used. Preferably, the doping material of the light-emitting layer includes at least one of a compound having the structure shown in Formula II and a compound having the structure shown in Formula III.

[0036]

[0037] Formula II;

[0038]

[0039] Formula III;

[0040] Among them, Ar 21 Ar 22 Each is independently selected from any one of substituted or unsubstituted C6-C20 aryl groups or substituted or unsubstituted C3-C20 heteroaryl groups;

[0041] R 21 R 22 and R 23 Each is independently selected from any one of hydrogen, C1-C12 straight-chain or branched alkyl, and C6-C12 cycloalkyl;

[0042] Ar 21 Ar 22 The substituents described herein are each independently selected from C1-C5 straight-chain or branched alkyl groups or C6-C12 aryl groups;

[0043] Ar 31 Ar 32 Ar 33 and Ar 34 Each is independently selected from any one of substituted or unsubstituted C6-C22 aryl groups or substituted or unsubstituted C12-C40 heteroaryl groups;

[0044] R 31 Selected from any one of H, phenyl, naphthyl, or biphenyl;

[0045] a is selected from 0 or 1;

[0046] Ar 31 Ar 32 Ar 33 Ar 34 The substituents described herein are each independently selected from cyano, C1-C5 straight-chain or branched alkyl, or C6-C12 aryl.

[0047] Preferably, in formula II, the Ar 21 Ar 22 Each independently selected , , , , , , , , , , , , , , , , Any of the following, with dashed lines representing connection points.

[0048] Preferably, in formula II, R 21 R 22 and R 23 Each is independently selected from any one of hydrogen, methyl, ethyl, propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclohexyl, or adamantyl.

[0049] Preferably, in formula III, the Ar 31 Ar 32 Ar 33 and Ar 34 Each independently selected , , , , , , , , , Any one or at least two of the above, with dashed lines indicating connection sites.

[0050] Preferably, the compound having the structure shown in Formula II is selected from any one of the following compounds:

[0051] .

[0052] Preferably, the compound having the structure shown in Formula III is selected from any one of the following compounds:

[0053] .

[0054] In this invention, no special restrictions are placed on the host material of the light-emitting layer; any host material known in the art can be used. Preferably, the host material of the light-emitting layer comprises a compound having the structure shown in Formula IV:

[0055]

[0056] Formula IV

[0057] In Formula IV, the Ar 11 Ar 12Each is independently selected from any one of substituted or unsubstituted C6~C40 (e.g., C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36, C40) aryl groups and substituted or unsubstituted C12~C40 (e.g., C12, C16, C20, C24, C28, C30, C32, C36, C40) heteroaryl groups;

[0058] The R 11 R 12 Each is independently selected from any one of the following: substituted or unsubstituted C1-C6 straight-chain or branched alkyl groups (e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, hexyl); substituted or unsubstituted C6-C40 (e.g., C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36, C40) aryl groups; and substituted or unsubstituted C12-C40 (e.g., C12, C16, C20, C24, C28, C30, C32, C36, C40) heteroaryl groups.

[0059] Ar 11 Ar 12 R 11 R 12 In this embodiment, each of the substituents is independently selected from at least one of the following: C1-C6 straight-chain or branched alkyl groups (e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, hexyl), C6-C20 (e.g., C6, C8, C10, C12, C16, C20) aryl, and C6-C20 heteroaryl (e.g., C6, C8, C10, C12, C16, C20);

[0060] The m and n are each independently selected from integers from 0 to 4, for example, they can be 0, 1, 2, 3, 4;

[0061] In the compound shown in Formula IV, each H atom can be independently replaced by a D atom.

[0062] Preferably, in formula IV, the Ar 11 Ar 12 Each independently selected , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Any one of them.

[0063] Preferably, in formula I, R 11 R 12 Each is independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, , Any one of them.

[0064] Preferably, in formula I, Ar 11 Selected from , , , , , , , , , , Any one of them.

[0065] Preferably, in formula I, Ar 12 Selected from , , , , , , , , , , Any one of them.

[0066] Preferably, the organic thin film layer further includes a hole layer, which includes at least one of a hole transport layer, a hole injection layer, and an electron blocking layer. In this invention, no special limitations are placed on the materials used for the hole injection layer, hole transport layer, and electron blocking layer; any materials known in the art capable of hole injection, hole transport, and electron blocking can be used.

[0067] Preferably, the hole layer material (including the hole injection layer, the hole transport layer, and the electron blocking layer) may comprise a compound having the structure shown in the formula HT-GH4:

[0068]

[0069] HT-GH4

[0070] In formula HT-GH4, L 41 Selected from single-bonded, C6-C40 (e.g., C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36, or C40, etc.) aryl, and C6-C20 (e.g., C6, C8, C10, C12, C16, or C20, etc.) heteroaryl;

[0071] In formula HT-GH4, Ar 41 Ar 42 Each is independently selected from C6-C40 (e.g., C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36, or C40, etc.) aryl and C6-C20 (e.g., C6, C8, C10, C12, C16, or C20, etc.) heteroaryl;

[0072] In formula HT-GH4, X3 is selected from CR 41 R 42 Or NR 43 , where R 41 R 42 R 43Each is independently selected from substituted or unsubstituted phenyl groups (the substituents are selected from C1-C6 (e.g., C1, C2, C3, C4, C5, or C6) alkyl, C1-C6 (e.g., C1, C2, C3, C4, C5, or C6) alkoxy, dibenzofuranyl, naphthyl, triphenylene, fluoranyl, 9,9-dimethylfluorenyl, biphenyl, substituted or unsubstituted dibenzofuranyl (the substituent is phenyl), substituted or unsubstituted dibenzothiophenyl (the substituent is phenyl), dibenzofuran-substituted thiophenyl, C1-C6 (e.g., C1, C2, C3, C4, C5, or C6) alkyl, R 41 R 42 A ring can be formed by connecting the links with a single key.

[0073] Thirdly, the present invention provides a display device comprising the organic electroluminescent device as described in the second aspect.

[0074] Compared with the prior art, the present invention has the following beneficial effects:

[0075] This invention designs the structure of triazine compounds to make them suitable as electron transport materials for OLED light-emitting devices, resulting in OLED light-emitting devices with lower driving voltage, higher current efficiency, and longer lifespan. Detailed Implementation

[0076] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0077] Synthesis Example 1

[0078] This synthetic example provides compound 1 and its synthetic method, which is as follows:

[0079]

[0080] Under nitrogen atmosphere, 80 mL of dioxane and 30 mL of water were added to a three-necked flask, followed by 1.2 g of intermediate 1-1, 3.9 g of intermediate 1-2, 2.12 g of sodium carbonate, and 0.23 g of tetraphenylphosphine palladium. The mixture was slowly heated to reflux for 8 h, then cooled to room temperature. Water and chloroform were added to separate the layers. The organic layer was washed with water and dried with magnesium sulfate. After removing the desiccant, the mixture was concentrated to dryness and crystallized with a mixed solvent of toluene and chloroform to obtain compound 1 (2.6 g).

[0081] The obtained compound 1 was subjected to mass spectrometry detection, and the mass-to-charge ratio (m / z) was measured to be 858.43.

[0082] Synthesis Examples 2-7

[0083] Synthetic Examples 2-7 each provide a compound. The synthesis method of the compound is the same as that of Compound 1 provided in Synthetic Example 1, using the corresponding starting materials. The amounts of starting materials and other reagents can be adjusted according to commonly known methods. The mass spectra of the prepared compounds were tested. See Table 1 below for details.

[0084] Table 1

[0085]

[0086]

[0087] Other compounds for which specific synthetic steps are not listed can be prepared using common knowledge in the field, combined with the above synthetic examples.

[0088] The specific structures of the compounds used in the following device embodiments and device comparative examples are shown below:

[0089] , , , , , , , , , , , , , , , , , , , .

[0090] The synthesis of compound DE2:

[0091]

[0092] Following the synthesis of compound 1, compound DE2 was prepared.

[0093] The obtained compound DE2 was analyzed by mass spectrometry, and the mass-to-charge ratio (m / z) was found to be 768.30.

[0094] Synthesis of compound DE3:

[0095]

[0096] Following the synthesis of compound 1, compound DE3 was prepared.

[0097] The obtained compound DE3 was analyzed by mass spectrometry, and the mass-to-charge ratio (m / z) was found to be 772.33.

[0098] The synthesis of compound DE4:

[0099]

[0100] Compound DE4 was prepared by referring to the synthesis of compound 1.

[0101] The obtained compound DE4 was analyzed by mass spectrometry, and the mass-to-charge ratio (m / z) was found to be 924.39.

[0102] The synthesis of compound DE5:

[0103]

[0104] Compound DE5 was prepared by referring to the synthesis of compound 1.

[0105] The obtained compound DE5 was analyzed by mass spectrometry, and the mass-to-charge ratio (m / z) was found to be 888.39.

[0106] Device Example 1

[0107] Device Example 1 provides an organic electroluminescent device, the structure of which is: ITO / HTL (80nm) / BH:BD-2 (5%) (30nm) / electron transport material (30nm) / Al (150nm);

[0108] The fabrication method of the above-mentioned organic electroluminescent device is as follows:

[0109] Each layer of material was placed inside a vacuum chamber, and the vacuum was evacuated to 1×10⁻⁶. -5 ~1×10 -6 Pa is sequentially vacuum-deposited onto the cleaned ITO substrate. BH:BD-2 (5%) (30nm) refers to the co-evaporation of BH and BD-2 at a volume ratio of 95:5 to form a light-emitting layer with a thickness of 30nm.

[0110] BH is the main material for blue light emission, and BD-2 is the doping material for the emitting layer.

[0111] In the device provided in Device Example 1, HTL (80nm) is a hole transport layer and the electron transport material is compound 1H.

[0112] ITO refers to the anode, and Al (150nm) refers to the cathode.

[0113] Device Examples 2-5

[0114] Device Examples 2-5 each provide an organic electroluminescent device, which differs from Device Example 1 only in that the electron transport material is different (as shown in Table 2 below), while the other preparation steps are the same as those in Device Example 1.

[0115] Device Comparison Examples 1-4

[0116] Comparative Examples 1 to 4 each provide an organic electroluminescent device, which differs from Device Example 1 only in the electron transport material (as shown in Table 2 below). The other preparation steps are the same as those in Device Example 1.

[0117] Performance testing:

[0118] The luminance, driving voltage, current efficiency, and LT95 of the organic electroluminescent devices provided above were tested. The current efficiency was measured at a luminance of 1000 cd / m². 2 The corresponding value, LT95, refers to maintaining an initial device current density of 10 mA / cm². 2 The time required for the device efficiency to drop to 95% of the efficiency corresponding to the initial current density is constant, where the drive voltage, current efficiency, and LT95 are relative values ​​(based on device comparison example 1). The test results are shown in Table 2.

[0119] Table 2

[0120]

[0121] As shown in Table 2, the electron transport material used in Device Example 1 is Compound 1H, while the electron transport materials used in Device Comparative Example 1 and Device Comparative Example 2 are Compounds DE1 and DE2, respectively. In Compound 1H, each of the two triazine rings is connected to a 9,9-dimethylfluorene group, while in Compounds DE1 and DE2, neither of the two triazine rings has a 9,9-dimethylfluorene group; instead, they are connected to phenyl or biphenyl groups. The device voltage, efficiency, and lifetime of Device Example 1 are significantly improved compared to Device Comparative Examples 1 and 2. This is because the presence of the 9,9-dimethylfluorene group on the triazine ring increases the intermolecular forces, resulting in better film formation and film stability, and improved charge transport performance.

[0122] As shown in Table 2, in Comparative Example 3, compound DE3 was used as the electron transport material. In compound DE3, the two triazine rings are separated by only one benzene ring. Compared with compound 1H, which is separated by two benzene rings, the two triazine rings in compound DE3 are closer together. Since the LUMO is mainly distributed on the triazine rings in this type of molecular structure, the LUMO distribution on the two triazine rings of compound DE3 is partially shifted towards the benzene ring, which affects each other and affects the energy level distribution of the device. The voltage, efficiency, and lifetime of the fabricated device are poor. In contrast, in Device Example 1, the two triazine rings are separated by two benzene rings, so the LUMO distribution on the two triazine rings is independent and has little mutual influence. The energy level distribution of the device is suitable, and the voltage, efficiency, and lifetime of the fabricated device are better.

[0123] The test results in Table 2 also show that when Ar1 and Ar2 are both selected from dibenzofuranyl, the compound can significantly reduce the driving voltage of the device as an electron transport material; when Ar1 and Ar2 are both selected from 9,9-dimethylfluorenyl, the compound can significantly extend the life of the device as an electron transport material.

[0124] Device Examples 6-8

[0125] Device Examples 6-8 each provide an organic electroluminescent device, which differs from Device Example 1 only in that the electron transport material is different (as shown in Table 3 below), and the blue light host material of the light-emitting layer is replaced by BH1 instead of BHH. The other preparation steps are the same as those in Device Example 1.

[0126] Comparative Examples 4 and 5 each provide an organic electroluminescent device, which differs from Device Example 1 only in that the electron transport material is different (as shown in Table 3 below), and the blue light host material of the light-emitting layer is replaced by BH1 instead of BHH. The other preparation steps are the same as those in Device Example 1.

[0127] Table 3

[0128]

[0129] As shown in Table 3, in Comparative Example 4, compound DE4 was used as the electron transport material. The two triazine rings of compound DE4 were separated by three benzene rings, resulting in a device with poor voltage, efficiency, and lifetime. In Comparative Example 5, compound DE5 was used as the electron transport material. The two triazine rings of compound DE5 were connected by a 9,9-dimethylfluorene group, resulting in a device with poor voltage, efficiency, and lifetime. This is because the 9,9-dimethylfluorene group has greater rigidity, and compared with the freely rotating biphenyl group, the intermolecular forces are smaller, affecting the film-forming properties and film stability of the material.

[0130] In summary, this invention designs the structure of triazine compounds to make them suitable as electron transport materials for OLED light-emitting devices, resulting in OLED light-emitting devices with lower driving voltage, higher current efficiency, and longer lifespan.

[0131] The present invention has been illustrated with the above embodiments to describe the detailed process flow of the present invention. However, the present invention is not limited to the above detailed process flow, that is, it does not mean that the present invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the 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. A triazine compound, characterized in that, The triazine compounds have the structure shown in Formula I: Formula I In Formula I, Ar1 and Ar2 are each independently selected from any one of substituted or unsubstituted C6~C20 aryl and substituted or unsubstituted C6~C20 heteroaryl groups; In Ar1 and Ar2, the substituents are each independently selected from any one of D, F, cyano, and C1-C6 alkyl groups; R1 to R4 are each independently selected from any one of the C1 to C6 alkyl groups; In the compound of formula I, each H atom can be independently replaced by a D atom.

2. The triazine compound according to claim 1, characterized in that, The C6-C20 aryl groups are selected from phenyl, naphthyl, biphenyl, fluorenyl, triphenylene, fluoranyl, phenanthryl, and others. , Any one of them; Preferably, the C6-C20 heteroaryl group is selected from any one of dibenzofuranyl, dibenzothiophenyl, and carbazoleyl; Preferably, the C1-C6 alkyl group is selected from any one of methyl, ethyl, propyl, butyl, pentyl, and hexyl.

3. The triazine compound according to claim 1, characterized in that, Ar1 and Ar2 are each independently selected from phenyl, naphthyl, biphenyl, 9,9-dimethylfluorenyl, , Any one of dibenzofuranyl and dibenzothiophenyl; Preferably, Ar1 and Ar2 are both selected from dibenzofuranyl; Preferably, Ar1 and Ar2 are both selected from 9,9-dimethylfluorenyl.

4. The triazine compound according to claim 1, characterized in that, R1 to R4 are each independently selected from any one of methyl, ethyl, propyl, butyl, pentyl, and hexyl; Preferably, R1 to R4 are all selected from methyl groups.

5. The triazine compound according to claim 1, characterized in that, The triazine compound is selected from any one of the following substituted or unsubstituted compounds: ； The substitution refers to the replacement of at least one hydrogen atom in the above compound with a deuterium atom.

6. The triazine compound according to claim 1, characterized in that, The triazine compound is selected from any one of the following compounds: 、 、 、 、 、 、 、 。 7. An organic electroluminescent device, characterized in that, The organic electroluminescent device includes an anode, a cathode, and an organic thin film layer disposed between the anode and the cathode, wherein the organic thin film layer includes a triazine compound as described in any one of claims 1 to 6.

8. The organic electroluminescent device according to claim 7, characterized in that, The organic thin film layer includes an electron transport layer, and the material of the electron transport layer includes the aforementioned triazine compound.

9. The organic electroluminescent device according to claim 8, characterized in that, The organic thin film layer also includes a light-emitting layer, the material of which includes a host material and a dopant material.

10. The organic electroluminescent device according to claim 8, characterized in that, The organic thin film layer further includes a hole layer, which includes at least one of a hole transport layer, a hole injection layer, and an electron blocking layer.

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