A compound containing benzofurans and an organic light-emitting device using the compound.

Abstract

This invention relates to a compound containing benzofurans and an organic light-emitting device using the compound, belonging to the field of OLED materials. The compound has the structures shown in Formulas I and II. The compound of this invention exhibits good thermal stability and film-forming stability, as well as excellent light emission performance, and can be used to prepare OLED light-emitting devices, especially as the blue light host material for the emissive layer in OLED devices, effectively improving the luminous efficiency and lifespan of organic light-emitting devices.

Description

Technical Field

[0001] This invention relates to a benzofuran-containing compound that can be used in organic light-emitting elements and an organic light-emitting device using the compound, and more particularly to a benzofuran-containing compound that can be used as a light-emitting layer in an organic light-emitting element to achieve element characteristics such as high luminous efficiency, long lifespan and low voltage drive, an organic light-emitting device using the compound, and an organic light-emitting element including the compound. Background Technology

[0002] Organic light-emitting diodes (OLEDs) are display components that utilize self-emissive properties. They have a wider viewing angle and are thinner, lighter, and faster than liquid crystal displays. They can also achieve flexible displays, making them highly anticipated for use as full-color display components or lighting equipment.

[0003] Organic light emission typically refers to the phenomenon of converting electrical energy into light energy using organic materials. Organic light-emitting devices that utilize organic light emission usually have a structure that includes an anode, a cathode, and an organic layer sandwiched between the anode and the cathode.

[0004] To improve the efficiency and stability of organic light-emitting elements (OLEDs), the organic layer is often composed of a multi-layered structure made of different materials. For example, it may consist of a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer. When a voltage is applied between the two electrodes in this OLED structure, holes from the anode are injected into the organic layer, and electrons from the cathode are also injected into the organic layer. When the injected holes and electrons meet in the light-emitting layer, they form excitons. When these excitons release energy and transition to the ground state, they emit photons, thus producing light. This type of OLED is widely recognized for its self-emissive nature, high brightness, high efficiency, low driving voltage, wide viewing angle, high contrast, and high-speed response.

[0005] Currently, research on organic electroluminescent materials has been widely carried out in academia and industry. Among them, blue light-emitting host materials are an important component of organic electroluminescent devices. However, there is still much room for improvement in the stability and luminescent performance of blue light-emitting host materials, which restricts the industrialization of light-emitting devices. Therefore, designing and searching for a compound as a novel OLED material to overcome its shortcomings in practical applications is a key focus and future research trend in OLED materials. Summary of the Invention

[0006] The purpose of this invention is to provide a compound containing benzofurans and an organic light-emitting device using the compound. The compound has good thermal stability, and the light-emitting device prepared using the compound has high luminous efficiency and long service life.

[0007] This invention provides a benzofuran compound with the general structural formulas shown in Formula I and Formula II:

[0008]

[0009] In this case, ring A is a benzene ring or a naphthalene ring, specifically including the following structures:

[0010]

[0011] R is independently selected from substituted or unsubstituted C6–C6. 30 Aromatic hydrocarbon groups or C6-C 30 Aromatic heterocyclic groups;

[0012] X is selected from the following structures The dashed lines represent the connecting keys in the above general formula.

[0013] R1 and R2 are independently selected from C1 to C2, with or without substitution. 12 Alkyl group or substituted or unsubstituted C6-C 30 Aromatic hydrocarbon groups or C6-C 30 Aromatic heterocyclic group; Ar1 ​​is selected from substituted or unsubstituted C6-C6. 30 Aromatic hydrocarbon groups or C6-C 30 Aromatic heterocyclic groups;

[0014] R3 and R4 are independently selected from substituted hydrogen atoms, substituted or unsubstituted C1 to C4. 12 Alkyl group or substituted or unsubstituted C6-C 30 Aromatic hydrocarbon groups or C6-C 30 Aromatic heterocyclic groups;

[0015] Furthermore, the hydrogen atoms in compounds of formulas I and II can be independently replaced by deuterium atoms, F, CN, and C1~C. 12 Alkyl, C1-C 12 Alkyl groups or C6-C 30 Aryl or C6~C 30 A substitution in an aromatic heterocyclic group.

[0016] Preferably, C6 to C 30 The aromatic hydrocarbon group is selected from phenyl, biphenyl, terphenyl, naphthyl, indyl, fluorenyl, perylene, phenanthryl, pyrene, fluoranyl or benzophenanthryl.

[0017] Preferably, C6 to C30 The heteroatom in an aromatic heterocyclic group is selected from oxygen, sulfur, or nitrogen.

[0018] Preferably, C6 to C 30 The aromatic heterocyclic group is selected from one of benzofuran, benzothiophene, dibenzofuran, dibenzothiophene, carbazole, benzofuran-dibenzothiophene, benzofuran-dibenzofuran, benzofuran-carbazole, and benzofuran-thiophene.

[0019] Preferably, C6 to C 30 The aromatic heterocyclic group is preferably one of dibenzofuran, dibenzothiophene, or carbazole.

[0020] Preferably, the compound containing benzofurans is shown in any one of formulas 1 to 160:

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029] Furthermore, the hydrogen atoms in formulas 1 to 160 above can be wholly or partially replaced by deuterium atoms, and the resulting compounds are also within the scope of protection of this invention. An exemplary structure is shown below:

[0030]

[0031] The present invention also provides an organic light-emitting device comprising the aforementioned compound containing benzofurans.

[0032] Preferably, the organic light-emitting device includes a first electrode, a second electrode, and an organic layer disposed between the first electrode and the second electrode; the organic layer contains the aforementioned compound containing benzofurans.

[0033] Preferably, the organic layer is a light-emitting layer, and the compound containing benzofurans is used as the blue light host material of the light-emitting layer.

[0034] The beneficial effects of this invention are:

[0035] Compared with the prior art, the present invention provides a compound containing benzofurans and an organic light-emitting device using the compound. The compound containing benzofurans has the structures shown in Formula I and Formula II. The compound containing benzofurans of the present invention has good thermal stability and excellent light-emitting performance, and can be used to prepare organic electroluminescent devices, especially as a blue light host material in organic electroluminescent devices, which can effectively improve the luminous efficiency and lifespan of organic light-emitting devices. Detailed Implementation

[0036] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0037] It should be noted that, unless otherwise specified, the technical terms used in this invention have the same meaning as commonly understood by those skilled in the art.

[0038] The aromatic hydrocarbon group mentioned in this invention refers to the general term for the monovalent group remaining after removing a hydrogen atom from the aromatic carbon atom of an aromatic hydrocarbon molecule. It can be a monocyclic aryl or a fused-ring aryl, and can be selected from phenyl, biphenyl, terphenyl, naphthyl, anthracene, indene, fluorenyl, perylene, phenanthrene, pyrene, fluoranyl or benzophenanthrene, but is not limited thereto.

[0039] The aromatic heterocyclic group mentioned in this invention refers to the general term for groups obtained by replacing one or more aromatic nuclei carbons in an aryl group with heteroatoms. The heteroatoms include, but are not limited to, oxygen, sulfur, or nitrogen. The heteroaryl group can be a monocyclic heteroaryl group or a fused-ring heteroaryl group, such as benzofuran, benzothiophene, dibenzofuran, dibenzothiophene, benzofuran-thiophene, etc., but is not limited thereto.

[0040] This invention first provides a compound containing benzofurans, the general structural formula of which is shown in Formula I and Formula II:

[0041]

[0042] In this case, ring A is a benzene ring or a naphthalene ring, specifically including the following structures:

[0043]

[0044] R is independently selected from substituted or unsubstituted C6–C6. 30 Aromatic hydrocarbon groups or C6-C 30 Aromatic heterocyclic groups;

[0045] X is selected from the following structures The dashed lines represent the connecting keys in the above general formula.

[0046] R1, R2, R3, and R4 are independently selected from substituted or unsubstituted C1 to C4. 12 Alkyl group or substituted or unsubstituted C6-C 30 Aromatic hydrocarbon groups or C6-C 30 Aromatic heterocyclic group; Ar1 ​​is selected from substituted or unsubstituted C6-C6. 30 Aromatic hydrocarbon groups or C6-C 30 Aromatic heterocyclic groups;

[0047] According to the present invention, the compound containing benzofurans is preferably any one of formulas 1 to 160:

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056] Furthermore, the hydrogen atoms in formulas 1 to 160 above can be wholly or partially replaced by deuterium atoms, and the structures resulting from deuterium atom substitution are also within the scope of protection of this patent. Exemplary structures include the following:

[0057]

[0058] The above lists some specific structural forms of the benzofuran-containing compounds of the present invention. However, the benzofuran-containing compounds of the present invention are not limited to these listed chemical structures. Any compound based on the structures shown in Formula I and Formula II, where R and X are groups as defined above, should be included.

[0059] This invention does not impose special requirements on the conditions of the above-described reactions; conventional conditions for such reactions well known to those skilled in the art are sufficient. This invention also does not impose special restrictions on the source of the raw materials used in the above-described reactions; the raw materials or intermediates can be commercially available products or prepared using methods well known to those skilled in the art.

[0060] The present invention also provides an organic light-emitting device, comprising the aforementioned compound containing benzofurans. The organic light-emitting device may be any organic light-emitting device well known to those skilled in the art. Preferably, the organic light-emitting device of the present invention comprises a first electrode, a second electrode, and an organic layer disposed between the first electrode and the second electrode; the organic layer comprises the aforementioned compound containing benzofurans. The organic layer may include at least one of a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer. Preferably, the compound containing benzofurans is used as the blue light host material in the organic layer.

[0061] The present invention does not impose any particular restrictions on the source of the raw materials used in the following embodiments, which can be products sold directly on the market or prepared by methods known to those skilled in the art.

[0062] Synthesis Example 1: Synthesis of Compound 1

[0063]

[0064] 0.1 mol of bromide 1, 0.12 mol of boric acid 1, 0.2 mol of potassium carbonate, 0.005 mol of tetra(triphenylphosphine)palladium, 300 mL of toluene, 150 mL of ethanol, and 150 mL of water were added to a reaction flask. The mixture was refluxed under nitrogen protection for 8 hours. After the reaction was stopped, the mixture was cooled and filtered directly. The resulting filter cake was dissolved in toluene and passed through a column. The column chromatography solution was concentrated and recrystallized from toluene to obtain compound 1. Mass spectrometry analysis of compound 1 yielded the following results:

[0065] Mass spectrometry m / z: 486.20. Measured elemental content (%): C, 91.33; H, 5.39.

[0066] Synthesis Example 2: Synthesis of Compound 2

[0067]

[0068] Following the synthesis method of Synthesis Example 1, boric acid 1 was replaced with boric acid 2 in Synthesis Example 1, with all other operations remaining unchanged, to obtain compound 2. Mass spectrometry analysis of compound 2 was performed, and the results are as follows:

[0069] Mass spectrometry m / z: 486.20. Measured elemental content (%): C, 91.33; H, 5.39.

[0070] Synthesis Example 3: Synthesis of Compound 3

[0071]

[0072] Following the synthesis method of Synthesis Example 1, bromine compound 1 was replaced with bromine compound 2, with all other operations remaining unchanged, to obtain compound 3. Mass spectrometry analysis of compound 3 yielded the following results:

[0073] Mass spectrometry m / z: 460.15. Measured elemental content (%): C, 88.67; H, 4.38.

[0074] Synthesis Example 4: Synthesis of Compound 4

[0075]

[0076] Following the synthesis method of Example 3, boric acid 1 was replaced with boric acid 2, while all other operations remained unchanged, to obtain compound 4. Mass spectrometry analysis of compound 4 yielded the following results:

[0077] Mass spectrometry m / z: 460.15. Measured elemental content (%): C, 88.67; H, 4.38.

[0078] Synthesis Example 5: Synthesis of Compound 7

[0079]

[0080] Following the synthesis method of Synthesis Example 1, bromine derivative 1 was replaced with bromine derivative 3, with all other operations remaining unchanged, to obtain compound 7. Mass spectrometry analysis of compound 7 yielded the following results:

[0081] Mass spectrometry m / z: 535.19. Measured elemental content (%): C, 89.69; H, 4.70; N, 2.61.

[0082] Synthesis Example 6: Synthesis of Compound 8

[0083]

[0084] Following the synthesis method of Synthesis Example 5, but replacing boric acid 1 with boric acid 2, while keeping all other operations unchanged, compound 8 was obtained. Mass spectrometry analysis of compound 8 yielded the following results:

[0085] Mass spectrometry m / z: 535.19. Measured elemental content (%): C, 89.69; H, 4.70; N, 2.61.

[0086] Synthesis Example 7: Synthesis of Compound 5

[0087]

[0088] Add 0.1 mol of bromide 4, 0.12 mol of o-bromophenylboronic acid 1, 0.2 mol of potassium carbonate, 0.005 mol of tetra(triphenylphosphine)palladium, 300 mL of toluene, 150 mL of ethanol, and 150 mL of water to the reaction flask. Under nitrogen protection, reflux the mixture for 8 h, then stop the reaction. After cooling, filter directly. Dissolve the resulting filter cake in toluene and pass it through a column. Concentrate the column chromatography solution and recrystallize it from toluene to obtain intermediate 5-1. Using 500 ml of tetrahydrofuran solvent, 0.1 mol of intermediate 5-1 was added under nitrogen protection and the temperature was lowered to -75 to -80 °C. 0.3 mol of n-butyllithium was added dropwise. After the addition was complete, the temperature was maintained at -75 to -80 °C for 1 h. Then, 0.3 mol of dimethyldichlorosilane was added dropwise while maintaining the temperature at -75 to -80 °C for 1 h. The temperature was then slowly raised to room temperature and stirred for 2 h. The reaction solution was then slowly poured into an ice-water mixture to quench the reaction. The mixture was separated, washed with water, and extracted twice with ethyl acetate. The combined organic phases were dried, passed through silica gel, concentrated, and the solvent was removed. The resulting solid was recrystallized from toluene and ethanol to obtain intermediate 5-2.

[0089] Dissolve 0.1 mol of intermediate 5-2 in 500 ml of tetrahydrofuran, add 0.12 mol of NBS, heat to 60 °C and react for 12 h, add 1000 ml of water and 200 ml of ethanol, precipitate solid, filter directly, and recrystallize the obtained filter cake with toluene and ethanol to obtain intermediate 5-3.

[0090] Referring to Synthesis Example 1, intermediate 5-3 was used to replace bromide 1 in Synthesis Example 1, with all other operations remaining unchanged, to obtain compound 5. Mass spectrometry analysis of compound 5 was performed, and the results are as follows:

[0091] Mass spectrometry m / z: 502.18. Measured elemental composition (%): C, 86.02; H, 5.21; Si, 5.59.

[0092] Other compounds can be obtained using similar synthetic methods.

[0093] In this invention, the specific structure of the materials used in the following application examples is as follows:

[0094]

[0095]

[0096] Device Example 1

[0097] The device embodiment provides an organic electroluminescent device, using compound 1 provided in synthesis embodiment 1 of the present invention as the host material of the light-emitting layer; the structure of the organic electroluminescent device is as follows:

[0098] ITO / HT (40nm) / Emitting layer main material: BD-23% (30nm) / TPBI (30nm) / LiF (0.5nm) / Al (150nm).

[0099] The fabrication method of the above-mentioned organic electroluminescent device is as follows:

[0100] The glass substrate coated with an ITO transparent conductive layer (as the anode) was ultrasonically treated in a cleaning agent, then rinsed in deionized water, then ultrasonically degreased in a mixed solvent of acetone and ethanol, then baked in a clean environment until completely dehydrated, cleaned with ultraviolet light and ozone, and bombarded with a low-energy cation beam to improve the surface properties and enhance the bonding ability with the hole layer.

[0101] The 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. The light-emitting layer substrate material: BD-2 3% (30nm) refers to the fact that in the device, the light-emitting layer substrate material and BD-2 are co-evaporated at a volume ratio of 97:3 to form the light-emitting layer, with a thickness of 30nm.

[0102] Device Examples 2-20

[0103] Device Examples 2-20 each provide an organic electroluminescent device, which differs from Device Example 1 only in that the main material of the light-emitting layer is different (see Table 1 below), while other conditions are the same as those in Device Example 1.

[0104] Device Comparison Examples 1-15

[0105] Comparative Examples 1-15 each provide an organic electroluminescent device, which differs from Device Example 1 only in that the main material of the light-emitting layer is different (see Table 1 below), while other conditions are the same as Device Example 1.

[0106] Performance testing

[0107] Test Methods: The driving voltage, current efficiency, and lifetime (LT90) of the OLED devices provided above were tested using the OLED-1000 multi-channel accelerated aging lifetime and color performance analysis system manufactured by Hangzhou Yuanfang. LT90 refers to the time required for the brightness to decrease to 90% of its original brightness while maintaining an initial brightness of 1000 nits at a constant current density. Test items included the brightness, driving voltage, and current efficiency of the organic electroluminescent device. The driving voltage, current efficiency, and LT90 data were all based on a brightness of 1000 cd / m². 2 The relative values ​​at different times. The performance test results of organic electroluminescent devices are shown in Table 1 below:

[0108] Table 1

[0109]

[0110]

[0111] As shown in Table 1, this invention, through molecular design, has obtained compounds with benzofuran-like structures. The compounds with benzofuran-like structures provided by this invention can be used as the main material for the light-emitting layer of OLED light-emitting devices, enabling these devices to have lower driving voltage, higher current efficiency, and longer lifetime.

[0112] Furthermore, through comparisons between Device Example 1 and Device Comparative Example 10, Device Example 2 and Device Comparative Example 11, Device Example 3 and Device Comparative Example 12, Device Example 4 and Device Comparative Example 13, Device Example 5 and Device Comparative Example 14, Device Example 6 and Device Comparative Example 15, it is demonstrated that the deuteration of the compound of the present invention can significantly improve the lifetime of OLED light-emitting devices.

[0113] 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 compound containing benzofurans, characterized in that, The structures of the compounds containing benzofurans are shown in any one of formulas 1 to 160: Furthermore, the hydrogen atoms in formulas 1 to 160 can be completely or partially replaced by deuterium atoms.

2. An organic light-emitting device, characterized in that, It includes the benzofuran compound as described in claim 1.

3. The organic light-emitting device according to claim 2, characterized in that, The organic light-emitting device includes a first electrode, a second electrode, and an organic layer disposed between the first electrode and the second electrode; the organic layer contains the benzofuran compound as described in claim 1.

4. The organic light-emitting device according to claim 3, characterized in that, The organic layer is the light-emitting layer, and the compound containing benzofurans is used as the blue light host material of the light-emitting layer.

Images