A light-emitting auxiliary material, a preparation method thereof, an organic electroluminescent device, and an organic electroluminescent apparatus

Abstract

The application provides a light-emitting auxiliary material and a preparation method thereof, and a structural general formula is shown in the description. The compound is obtained by connecting two main structures to triarylamine, wherein a diphenyl furan group, a diphenyl thiophene group and a 9,9-dimethyl fluorene group are one of the main structures, and the other main structure is a 9-methyl fluorene group bridged to triarylamine through a phenylene group. The light-emitting auxiliary material can not only adjust the molecular HOMO / LUMO energy level by using the electronegativity of polar atoms O, S and C, but also can use the buffer of the phenylene group to extend the system and enhance the molecular fluidity, so as to improve the light-emitting efficiency of the device. After the light-emitting auxiliary material is used in the device, the hole transport energy barrier can be reduced, and the migration rate and the light-emitting efficiency can be improved.

Description

Technical Field

[0001] The present invention belongs to the field of organic electroluminescence, and relates to a luminescence auxiliary material and a preparation method thereof, an organic electroluminescent device and an organic electroluminescent apparatus. Background Art

[0002] Organic electroluminescence (OLED) refers to the phenomenon of converting electrical energy into light energy using organic substances. Organic light-emitting devices that utilize organic electroluminescence typically include an anode, a cathode, and an organic layer formed between the anode and cathode electrodes or outside the two electrodes.

[0003] In order to solve the problems of lifespan and efficiency, a luminescent auxiliary layer (multi-layer hole transport layer) is usually added between the hole transport layer and the light-emitting layer. The luminescent auxiliary layer mainly plays the role of assisting the hole transport layer, so it is sometimes also called the second hole transport layer. The luminescent auxiliary layer can enable the holes transferred from the anode to move smoothly to the light-emitting layer, and can block the electrons transferred from the cathode to confine the electrons in the light-emitting layer, reduce the potential barrier between the hole transport layer and the light-emitting layer, reduce the driving voltage of the organic electroluminescent device, and further increase the utilization rate of holes, thereby improving the luminous efficiency and life of the device. Therefore, the role of the luminescent auxiliary material is so important.

[0004] Research on organic electroluminescent materials has been widely carried out in academia and industry, but stable and efficient organic layer materials for organic light-emitting devices have not yet been fully developed. In addition, the industrialization process of this technology faces many key issues. Therefore, how to develop a new luminescent auxiliary material has always been an urgent problem to be solved by technicians in this field. Summary of the Invention

[0005] In view of this, the present invention provides a luminescent auxiliary material and a preparation method thereof. The luminescent auxiliary material of the present invention is applied to a specific light-emitting device, which has low driving voltage, high luminescent efficiency and long service life.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The first technical purpose of the present invention is to provide a luminescence auxiliary material, the general structural formula of the luminescence auxiliary material is Chemical Formula I:

[0008]

[0009] In the chemical formula I:

[0010] X is independently selected from one of O, S, and C(CH3)2;

[0011] R is independently selected from hydrogen, cyano, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C6-C18 aryl, substituted or unsubstituted C3-C18 heteroaryl, wherein the heteroatom contains at least one of O, S, N, Si, and Se;

[0012] Ar1 represents a substituted or unsubstituted C6-C18 aryl group, a substituted or unsubstituted C6-C18 heteroaryl group, wherein the heteroatom contains at least one of O, S, N, Si, and Se;

[0013] Ar2 and Ar3 are the same as or different from each other and represent a substituted or unsubstituted C6-C18 aryl group or a substituted or unsubstituted C6-C18 heteroaryl group, wherein the heteroatom contains at least one of O, S, N, Si and Se.

[0014] Preferably, R is independently selected from hydrogen, cyano, substituted or unsubstituted C1-C3 alkyl, substituted or unsubstituted C6-C12 aryl;

[0015] Ar1 represents a substituted or unsubstituted C6-C18 aryl group;

[0016] Ar2 and Ar3 are the same or different and represent a substituted or unsubstituted C6-C18 aryl group;

[0017] Further preferably, R is selected from hydrogen, methyl, and benzene ring;

[0018] Ar1 is selected from benzene ring, biphenyl, terphenyl;

[0019] Ar2 and Ar3 are selected from any one of the following structures:

[0020]

[0021] Furthermore, Chemical Formula I is shown below:

[0022]

[0023] Furthermore, Chemical Formula I is shown below:

[0024]

[0025] In the present invention, "substituted" means substituted by one, two or more substituents selected from the group consisting of hydrogen, deuterium, halogen, cyano, trifluoromethyl, methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methylbutyl, 1-ethylbutyl, pentyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, 1-methylhexyl, phenyl, naphthyl, anthracenyl, phenanthrenyl, thienyl, furyl, pyrrolyl, benzothienyl, benzofuranyl, pyridyl, indolyl, cyclopentanyl, cyclohexyl or adamantyl.

[0026] In the above technical solution, the light-emitting auxiliary material is any one of the following structures, but is not limited thereto:

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044] A second technical objective of the present invention is to provide a method for preparing the aforementioned luminescence auxiliary material. The luminescence auxiliary material of the present invention can be prepared by a synthesis method known to those skilled in the art. Alternatively, the following reaction scheme is preferably used for preparation. The specific synthesis route is as follows:

[0045]

[0046] In the above formula, R, Ar1-Ar3, and X are as defined in the above chemical formula I, and Hal1 and Hal2 are independently selected from chlorine and bromine.

[0047] With respect to the undisclosed complex raw materials, the compound is synthesized by adopting the classic Buchwald-Hartwig coupling reaction and applied to the present invention.

[0048] Specific preparation method:

[0049] Step 1 specifically includes the following steps:

[0050] Synthesis of intermediate 1: Raw material A (1.0 eq), raw material B (1.0-1.2 eq) and sodium tert-butoxide (2.0 eq) were dissolved in toluene. Under nitrogen protection, tris(dibenzylideneacetone)dipalladium (0.01-0.02 eq) and tri-tert-butylphosphine (0.05 eq) were added, stirred evenly, heated to 100-120° C., and refluxed for 1-4 hours. The reaction was detected by thin layer chromatography. After the reaction was completed, the temperature was slightly lowered and filtered using diatomaceous earth to remove salt and catalyst. The filtrate was cooled to room temperature and washed three times with water. The organic phase was retained, and the aqueous phase was then extracted with dichloromethane. After the organic phases were combined, the solvent was removed using a rotary evaporator. Intermediate 1 was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (the volume ratio of the two was 1:6) to obtain intermediate 1.

[0051] Step 2 specifically includes the following steps:

[0052] Synthesis of Chemical Formula I: Intermediate 1 (1.0 eq), raw material C (1.0-1.2 eq) and sodium tert-butoxide (2.0 eq) were dissolved in toluene. Under nitrogen protection, tris(dibenzylideneacetone)dipalladium (0.01-0.02 eq) and tri-tert-butylphosphine (0.05 eq) were added, stirred evenly, heated to 110-120° C., and refluxed for 8-12 hours. The reaction was monitored by thin layer chromatography. After the reaction was completed, the temperature was slightly lowered and filtered through diatomaceous earth to remove salts and catalyst. The filtrate was cooled to room temperature and washed three times with water. The organic phase was retained, and the aqueous phase was extracted with dichloromethane. After the organic phases were combined, the solvent was removed using a rotary evaporator. The product of Chemical Formula I was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (volume ratio of the two was 1:8) to obtain the product.

[0053] Furthermore, the present invention also seeks to protect the use of the above-mentioned luminescence auxiliary material in the preparation of an organic electroluminescent device.

[0054] Specifically, the organic electroluminescent device includes a first electrode, a second electrode, and one or more organic layers disposed between the first electrode and the second electrode; and

[0055] The organic layer includes at least one of a hole injection layer, a hole transport layer, an electron blocking layer, a luminescence auxiliary layer, a luminescent layer, a hole blocking layer, an electron transport layer, an electron injection layer and a capping layer; and,

[0056] The luminescence auxiliary layer contains the luminescence auxiliary material.

[0057] Furthermore, the present invention seeks to protect the use of the organic electroluminescent device in an organic electroluminescent apparatus.

[0058] Specifically, the organic electroluminescent device includes but is not limited to a flat panel display, a computer monitor, a medical monitor, a television, a billboard, a lamp for interior or exterior lighting and / or signaling, a head-up display, a fully transparent or partially transparent display, a flexible display, a laser printer, a telephone, a mobile phone, a tablet, a photo album, a personal digital assistant (PDA), a wearable device, a laptop computer, a digital camera, a video camera, a viewfinder, a microdisplay, a three-dimensional display, a virtual reality or augmented reality display, a vehicle, a video wall comprising multiple displays tiled together, a theater or venue screen, a light therapy device and a sign.

[0059] It can be seen from the above technical solutions that compared with the prior art, the present invention has the following beneficial effects:

[0060] The present invention utilizes two main structures connected to a triarylamine: a dibenzofuran group, a dibenzothiophene group, and a 9,9-dimethylfluorene group. The other main structure is a 9-methylfluorene group bridged to the triarylamine via a phenylene group. This luminescent auxiliary material not only utilizes the electronegativity of polar atoms O, S, and C to adjust the molecular HOMO / LUMO energy levels, but also utilizes the buffering effect of the phenylene group to extend the system and enhance molecular mobility, thereby improving the luminous efficiency of the device.

[0061] In addition, since triarylamine itself contains nitrogen atoms containing lone pairs of electrons, the electrons on its nitrogen atoms are transferred by transition under the action of an external electric field, and the molecules generate holes, thereby realizing the reverse transfer of holes. On the other hand, triarylamine itself has good hole transport ability. By connecting the above two main structures on the triarylamine structure, a geometric structure is added on the basis of the non-planar molecular structure to form a compound with a larger spatial configuration. Its unique structure is conducive to the transport of holes, thereby obtaining a higher hole transport efficiency, which can improve the luminous efficiency and life of the device and reduce the driving voltage.

[0062] Furthermore, the luminescence-assisting material described herein incorporates a simple triarylamine structure as a substituent on the other side of dibenzofuran, dibenzothiophene, and 9,9-dimethylfluorene. This not only improves injection efficiency and hole transport efficiency, reducing driving voltage, but also creates a more distorted configuration, resulting in a better vapor deposition morphology. Furthermore, it extends the system to avoid regionalization of carrier migration. When used in devices, this luminescence-assisting material can lower the hole transport barrier, improving migration rate and luminescence efficiency.

[0063] It can be seen that the luminescence auxiliary material disclosed in the present invention has good market application and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of the intermediate 1 provided in Example 1 of the present invention.

[0065] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of compound 2 provided in Example 1 of the present invention.

[0066] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of compound 22 provided in Example 2 of the present invention.

[0067] Figure 4 This is the hydrogen nuclear magnetic resonance spectrum of compound 75 provided in Example 3 of the present invention.

[0068] Figure 5 This is the hydrogen nuclear magnetic resonance spectrum of compound 96 provided in Example 4 of the present invention. DETAILED DESCRIPTION

[0069] Example 1

[0070]

[0071] Step 1 specifically includes the following steps:

[0072] Synthesis of intermediate 1: Raw material A-2 (1.0 eq, CAS number: 60253-06-7), raw material B-2 (1.1 eq, CAS number: 1795019-74-7) and sodium tert-butoxide (2.0 eq) were dissolved in toluene. Under nitrogen protection, tris(dibenzylideneacetone)dipalladium (0.02 eq) and tri-tert-butylphosphine (0.05 eq) were added, stirred evenly, heated to 110°C, and refluxed for 3 hours; the reaction was detected by thin layer chromatography. After the reaction was completed, the temperature was slightly lowered and filtered using diatomaceous earth to remove salt and catalyst. After the filtrate was cooled to room temperature, it was washed three times with water, the organic phase was retained, and the aqueous phase was extracted with dichloromethane; after combining the organic phases, the solvent was removed using a rotary evaporator; and intermediate 1 was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (volume ratio of the two was 1:6) to obtain intermediate 1 (yield: 73.7%).

[0073] Step 2 specifically includes the following steps:

[0074] Synthesis of compound 2: Intermediate 1 (1.0 eq), raw material C-2 (1.0 eq, CAS number: 2671070-71-4) and sodium tert-butoxide (2.0 eq) were dissolved in toluene. Under nitrogen protection, tris(dibenzylideneacetone)dipalladium (0.02 eq) and tri-tert-butylphosphine (0.05 eq) were added, stirred evenly, heated to 120°C, and refluxed for 10 hours; the reaction was detected by thin layer chromatography. After the reaction was completed, the temperature was slightly lowered and filtered using diatomaceous earth to remove salt and catalyst. The filtrate was cooled to room temperature and washed three times with water. The organic phase was retained, and the aqueous phase was then extracted with dichloromethane; after combining the organic phases, the solvent was removed using a rotary evaporator; a mixed solution of dichloromethane and petroleum ether (the volume ratio of the two was 1:8) was purified by column chromatography to obtain compound 2 (yield: 82.5%).

[0075] The obtained compound 2 was tested and analyzed, and the results were as follows:

[0076] HPLC purity: >99.8%.

[0077] Mass spectrometry test: Waters XEVO TQD mass spectrometer, using ESI source.

[0078] Measured value MS (ESI, m / Z): [M+H] + =757.15.

[0079] Elemental analysis:

[0080] Calculated values: C, 88.86; H, 5.33; N, 3.70; O, 2.11;

[0081] The test values ​​are: C, 88.53; H, 5.46; B, 3.87; N, 2.22.

[0082] H NMR spectrum: Figure 1 (Compound 2-Intermediate 1), Figure 2 (Compound 2) shown.

[0083] Example 2

[0084]

[0085] Step 1 specifically includes the following steps:

[0086] Synthesis of intermediate 1: Raw material A-22 (1.0 eq, CAS number: 60253-06-7), raw material B-22 (1.1 eq, CAS number: 868699-95-0) and sodium tert-butoxide (2.0 eq) were dissolved in toluene. Under nitrogen protection, tris(dibenzylideneacetone)dipalladium (0.02 eq) and tri-tert-butylphosphine (0.05 eq) were added, stirred evenly, heated to 110°C, and refluxed for 3 hours; the reaction was detected by thin layer chromatography. After the reaction was completed, the temperature was slightly lowered and filtered using diatomaceous earth to remove salt and catalyst. After the filtrate was cooled to room temperature, it was washed three times with water, the organic phase was retained, and the aqueous phase was extracted with dichloromethane; after combining the organic phases, the solvent was removed using a rotary evaporator; and intermediate 1 was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (volume ratio of the two was 1:6) to obtain intermediate 1 (yield: 69.6%).

[0087] Step 2 specifically includes the following steps:

[0088] Synthesis of compound 22: Intermediate 1 (1.0 eq), raw material C-22 (1.0 eq, CAS number: 2377765-86-9) and sodium tert-butoxide (2.0 eq) were dissolved in toluene. Under nitrogen protection, tris(dibenzylideneacetone)dipalladium (0.02 eq) and tri-tert-butylphosphine (0.05 eq) were added, stirred evenly, heated to 120°C, and refluxed for 10 hours; the reaction was detected by thin layer chromatography. After the reaction was completed, the temperature was slightly lowered and filtered using diatomaceous earth to remove salt and catalyst. After the filtrate was cooled to room temperature, it was washed three times with water, the organic phase was retained, and the aqueous phase was extracted with dichloromethane; after combining the organic phases, the solvent was removed using a rotary evaporator; and a mixed solution of dichloromethane and petroleum ether (volume ratio of the two was 1:8) was purified by column chromatography to obtain compound 22 (yield: 80.2%).

[0089] The obtained compound 22 was tested and analyzed, and the results were as follows:

[0090] HPLC purity: >99.8%.

[0091] Mass spectrometry test: Waters XEVO TQD mass spectrometer, using ESI source.

[0092] Measured value MS (ESI, m / Z): [M+H] + =681.06.

[0093] Elemental analysis:

[0094] Calculated values: C, 88.21; H, 5.33; N, 4.11; O, 2.35;

[0095] The test values ​​are: C, 87.86; H, 5.47; B, 4.27; N, 2.47.

[0096] H NMR spectrum: Figure 3 (Compound 22).

[0097] Example 3

[0098]

[0099] Step 1 specifically includes the following steps:

[0100] Synthesis of intermediate 1: Raw material A-75 (1.0 eq, CAS number: 60253-06-7), raw material B-75 (1.1 eq, CAS number: 868699-95-0) and sodium tert-butoxide (2.0 eq) were dissolved in toluene. Under nitrogen protection, tris(dibenzylideneacetone)dipalladium (0.02 eq) and tri-tert-butylphosphine (0.05 eq) were added, stirred evenly, heated to 110°C, and refluxed for 3 hours; the reaction was detected by thin layer chromatography. After the reaction was completed, the temperature was slightly lowered and filtered using diatomaceous earth to remove salt and catalyst. After the filtrate was cooled to room temperature, it was washed three times with water, the organic phase was retained, and the aqueous phase was extracted with dichloromethane; after combining the organic phases, the solvent was removed using a rotary evaporator; and intermediate 1 was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (volume ratio of the two was 1:6) to obtain intermediate 1 (yield: 59.8%).

[0101] Step 2 specifically includes the following steps:

[0102] Synthesis of compound 75: Intermediate 1 (1.0 eq), raw material C-75 (1.0 eq, CAS number: 2603276-71-5) and sodium tert-butoxide (2.0 eq) were dissolved in toluene. Under nitrogen protection, tris(dibenzylideneacetone)dipalladium (0.02 eq) and tri-tert-butylphosphine (0.05 eq) were added, stirred evenly, heated to 120°C, and refluxed for 10 hours; the reaction was detected by thin layer chromatography. After the reaction was completed, the temperature was slightly lowered and filtered using diatomaceous earth to remove salt and catalyst. After the filtrate was cooled to room temperature, it was washed three times with water, the organic phase was retained, and the aqueous phase was extracted with dichloromethane; after combining the organic phases, the solvent was removed using a rotary evaporator; and a mixed solution of dichloromethane and petroleum ether (volume ratio of the two was 1:8) was purified by column chromatography to obtain compound 75 (yield: 76.7%).

[0103] The obtained compound 75 was tested and analyzed, and the results were as follows:

[0104] HPLC purity: >99.7%.

[0105] Mass spectrometry test: Waters XEVO TQD mass spectrometer, using ESI source.

[0106] Measured value MS (ESI, m / Z): [M+H] + =707.13.

[0107] Elemental analysis:

[0108] Calculated values: C, 90.05; H, 5.99; N, 3.96;

[0109] The test values ​​are: C, 89.77; H, 6.20; N, 4.12.

[0110] H NMR spectrum: Figure 4 (Compound 75).

[0111] Example 4

[0112]

[0113] Step 1 specifically includes the following steps:

[0114] Synthesis of intermediate 1: Raw material A-96 (1.0 eq, CAS number: 2128245-45-2), raw material B-96 (1.1 eq, CAS number: 2243-47-2) and sodium tert-butoxide (2.0 eq) were dissolved in toluene. Under nitrogen protection, tris(dibenzylideneacetone)dipalladium (0.01 eq) and tri-tert-butylphosphine (0.05 eq) were added, stirred evenly, heated to 100°C, and refluxed for 2 hours; the reaction was detected by thin layer chromatography. After the reaction was completed, the temperature was slightly lowered and filtered using diatomaceous earth to remove salt and catalyst. After the filtrate was cooled to room temperature, it was washed three times with water, the organic phase was retained, and the aqueous phase was extracted with dichloromethane; after combining the organic phases, the solvent was removed using a rotary evaporator; and intermediate 1 was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (volume ratio of the two was 1:6) to obtain intermediate 1 (yield: 63.5%).

[0115] Step 2 specifically includes the following steps:

[0116] Synthesis of compound 96: Intermediate 1 (1.0 eq), raw material C-96 (1.0 eq, CAS number: 2144799-55-1) and sodium tert-butoxide (2.0 eq) were dissolved in toluene. Under nitrogen protection, tris(dibenzylideneacetone)dipalladium (0.02 eq) and tri-tert-butylphosphine (0.05 eq) were added, stirred evenly, heated to 120°C, and refluxed for 10 hours; the reaction was detected by thin layer chromatography. After the reaction was completed, the temperature was slightly lowered and filtered through diatomaceous earth to remove salt and catalyst. The filtrate was cooled to room temperature and washed three times with water. The organic phase was retained, and the aqueous phase was then extracted with dichloromethane; after combining the organic phases, the solvent was removed using a rotary evaporator; and compound 96 was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (volume ratio of the two was 1:8) to obtain compound 96 (yield: 79.8%).

[0117] The obtained compound 96 was tested and analyzed, and the results were as follows:

[0118] HPLC purity: >99.6%.

[0119] Mass spectrometry test: Waters XEVO TQD mass spectrometer, using ESI source.

[0120] Measured value MS (ESI, m / Z): [M+H] + =773.21.

[0121] Elemental analysis:

[0122] Calculated values: C, 87.01; H, 5.22; N, 3.62; S, 4.15;

[0123] The test values ​​are: C, 86.65; H, 5.37; N, 3.80; S, 4.31.

[0124] H NMR spectrum: Figure 5 (Compound 96).

[0125] Example 5-51

[0126] The following compounds were synthesized by referring to the synthesis methods of Examples 1 to 4 and tested using a Waters XEVOTQD mass spectrometer. The precision values ​​were tested using an ESI source. The mass spectrometry test values ​​are shown in Table 1 below.

[0127] Table 1 Mass spectrometry test values ​​of Examples 5-51

[0128]

[0129]

[0130] In addition, it should be noted that other compounds of the present invention can be obtained by referring to the synthesis methods of the above-mentioned embodiments, so they will not be listed here one by one.

[0131] Another object of the present application is to provide an organic electroluminescent device, comprising a first electrode, a second electrode, and at least one organic layer disposed between the first electrode and the second electrode.

[0132] The organic material layer of the organic electroluminescent device may have either a single-layer structure or a multi-layer structure. For example, the organic electroluminescent device may have a structure including a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting auxiliary layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a hole blocking layer as organic material layers. However, the structure of the organic electroluminescent device is not limited thereto and may include a fewer number of organic material layers or a greater number of organic material layers.

[0133] As the anode material, a material with a large work function is generally preferred to facilitate hole injection into the organic material layer. Anode materials that can be used in the present invention include, but are not limited to: metals such as vanadium, chromium, copper, zinc, and gold, or alloys thereof; metal oxides such as zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); combinations of metals and oxides such as ZnO:Al or SnO2:Sb; and conductive polymers such as poly(3-methylthiophene), poly[3,4-(ethylene-1,2-dioxy)thiophene] (PEDOT), polypyrrole, and polyaniline.

[0134] The hole injection material is a material that advantageously receives holes from the anode at a low voltage, and the highest occupied molecular orbital (HOMO) of the hole injection material is between the work function of the anode material and the HOMO of the surrounding organic material layer. Hole injection materials specifically include metalloporphyrins, oligothiophenes, arylamine-based organic materials, hexanitrile hexaazatriphenylene-based organic materials, quinacridone-based organic materials, perylene-based organic materials, anthraquinone, polyaniline-based and polythiophene-based conductive polymers, but are not limited thereto and also include compounds capable of p-doping.

[0135] Hole transport materials are materials that can receive holes from the anode or hole injection layer and transport them to the light-emitting layer, preferably materials with high hole mobility. Examples include, but are not limited to, organic materials based on arylamines, conductive polymers, and block copolymers having both conjugated and non-conjugated portions.

[0136] The light-emitting layer can emit red, green or blue light and is formed of a phosphorescent material or a fluorescent material. The light-emitting material is a material that can emit light in the visible light region by receiving holes and electrons from the hole transport layer and the electron transport layer respectively and combining the holes with the electrons, preferably a material with a favorable quantum efficiency for fluorescence or phosphorescence. Specifically, it includes: 8-hydroxyquinoline aluminum (Alq3); carbazole-based compounds; diphenylethylene compounds; bis(2-methyl-8-hydroxyquinoline-N1,O8)-(1,1'-biphenyl-4-hydroxy)aluminum (BAlq); 10-hydroxybenzoquinoline-metal compounds; benzocarbazole-based, benzothiazole-based and benzimidazole-based compounds; poly(p-phenylene vinylene) (PPV)-based polymers; spirocyclic compounds; polyfluorene; rubrene, etc., but not limited thereto.

[0137] The host material of the light-emitting layer includes fused aromatic ring derivatives and heterocyclic compounds. Specifically, fused aromatic ring derivatives include anthracene derivatives, pyrene derivatives, naphthalene derivatives, pentacene derivatives, phenanthrene compounds, and fluoranthene compounds. Among them, heterocyclic compounds include carbazole derivatives, dibenzofuran derivatives, ladder-type furan compounds, and pyrimidine derivatives. However, the materials are not limited to these.

[0138] The electron transport layer facilitates electron transport. The electron transport material is a material that advantageously receives electrons from the cathode and transports them to the light-emitting layer, preferably a material with high electron mobility. Specifically, it includes: Al complexes of 8-hydroxyquinoline; complexes containing Alq3; organic free radical compounds; and hydroxyflavone-metal complexes. The thickness of the electron transport layer can range from 1 nm to 50 nm. An electron transport layer with a thickness of 1 nm or greater has the advantage of preventing a decrease in electron transport properties, while an electron transport layer with a thickness of 50 nm or less has the advantage of preventing an increase in the driving voltage for enhanced electron mobility caused by an excessively thick electron transport layer.

[0139] The electron injection layer can promote electron injection, and the electron injection material is preferably a compound having the following characteristics:

[0140] They have the ability to transport electrons and have an electron injection effect from the cathode, providing an excellent electron injection effect into the light-emitting layer or light-emitting material, preventing excitons generated in the light-emitting layer from migrating to the hole injection layer, and having excellent thin-film forming capabilities. Specifically, they include, but are not limited to, fluorenone, anthraquinone dimethane, diphenoquinone, thiopyran dioxide, azole, diazole, triazole, imidazole, perylenetetracarboxylic acid, fluorenylmethane, anthrone and their derivatives, metal complexes, and nitrogen-containing 5-membered ring derivatives.

[0141] Cathode materials are generally preferred, preferably those with a low work function to facilitate electron injection into the organic material layer. Specific cathode materials include, but are not limited to, metals such as magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin, and lead, or alloys thereof; and multilayer structures such as LiF / Al or LiO2 / Al.

[0142] Except for the light-emitting auxiliary layer disclosed in the present invention comprising chemical formula I, there is no special limitation on the materials of other layers in the OLED device.

[0143] The devices described herein can be used in organic light-emitting devices, including but not limited to flat panel displays, computer monitors, medical monitors, televisions, billboards, lights for interior or exterior lighting and / or signaling, heads-up displays, fully or partially transparent displays, flexible displays, laser printers, telephones, mobile phones, tablets, photo albums, personal digital assistants (PDAs), wearable devices, laptop computers, digital cameras, video cameras, viewfinders, microdisplays, three-dimensional displays, virtual reality or augmented reality displays, vehicles, video walls comprising multiple displays tiled together, theater or stadium screens, light therapy devices, and signs.

[0144] The organic electroluminescent device provided by the present invention is described in detail below with reference to specific embodiments.

[0145] Device Example 1: Preparation of red organic electroluminescent device

[0146] The structure of the prepared OLED device is: ITO anode / HIL / HTL / Prime / EML / HBL / ETL / EIL / cathode / CPL.

[0147] a. ITO anode: the coating thickness is The ITO (indium tin oxide)-Ag-ITO (indium tin oxide) glass substrate was cleaned twice in distilled water, ultrasonically washed for 30 minutes, and then repeatedly cleaned twice with distilled water, ultrasonically washed for 10 minutes. After washing, it was ultrasonically washed with methanol, acetone, and isopropanol in sequence (5 minutes each time), dried, and then transferred to a plasma cleaning machine for washing for 5 minutes. It was then sent to a vapor deposition machine, and the substrate was used as the anode, and other functional layers were evaporated on it in sequence.

[0148] b. HIL (hole injection layer): The hole injection layer materials HT and P-dopant were vacuum-deposited at a deposition rate of 97:3, with a thickness of 10 nm. The chemical formula of the materials is shown below.

[0149] c. HTL (hole transport layer): At a deposition rate of , 130 nm of HT was vacuum evaporated on the hole injection layer as a hole transport layer.

[0150] d. Prime (luminous auxiliary layer): The evaporation rate was 10 nm, and the compound 1 provided in the above embodiment was vacuum evaporated on the hole transport layer as a light-emitting auxiliary layer.

[0151] e. EML (light-emitting layer): Then on the above-mentioned light-emitting auxiliary layer, A host material (Host) and a dopant material (Dopant) were vacuum-deposited to a thickness of 20 nm as a light-emitting layer at a deposition rate of 97:3. The chemical formulas of the Host and Dopant are shown below.

[0152] f. HBL (hole blocking layer): At a deposition rate of , a hole blocking layer HB with a thickness of 5 nm was vacuum-deposited, and the chemical formula is shown below.

[0153] g. ETL (Electron Transport Layer): ET and Liq were vacuum-deposited to a thickness of 30 nm as an electron transport layer. The chemical formula of ET is shown below. The ET and Liq evaporation rate ratio was 50:50.

[0154] h. EIL (electron injection layer): The evaporation rate is 1 nm, and a Yb film layer is evaporated to form an electron injection layer.

[0155] i. Cathode: The evaporation rate ratio of magnesium and silver was 13nm, and the evaporation rate ratio was 1:9 to obtain an OLED device.

[0156] j. CPL (light extraction layer): At a deposition rate of , CPL with a thickness of 65 nm was vacuum-deposited on the cathode as a light extraction layer. The chemical formula of CPL is shown below.

[0157] K. The vapor-deposited substrate is then packaged. First, the cleaned cover is coated with UV glue using a glue coating device. The coated cover is then moved to the laminating section, where the vapor-deposited substrate is placed on top of the cover. Finally, the substrate and cover are laminated using a laminating device, and the UV glue is cured by light.

[0158]

[0159] Referring to the method provided in the above device embodiment 1, the corresponding compounds in Table 2 were selected to replace compound 1, and the light-emitting auxiliary layer was evaporated to prepare the corresponding organic electroluminescent devices, which were respectively recorded as device embodiments 2 to 51.

[0160] Device Comparison Examples 1-12:

[0161] This comparative example provides an organic electroluminescent device. The only difference between the preparation method of this organic electroluminescent device and that of Device Example 1 is that this organic electroluminescent device uses an existing comparative compound a1 instead of the luminescence auxiliary material (Compound 1) in Device Example 1 for vapor deposition. The chemical structure of comparative compound a1 is as follows:

[0162]

[0163] The driving voltage, luminous efficiency and lifespan of the organic electroluminescent devices obtained from the device examples 1 to 51 and the device comparative examples 1 to 12 were characterized at a brightness of 6000 (nits). The test results are shown in Table 2 below:

[0164] Table 2

[0165]

[0166]

[0167]

[0168] It can be seen from Table 2 that, compared with the organic electroluminescent device prepared using the luminescence auxiliary material provided by the present invention and the organic electroluminescent device prepared using the comparative example compound, the efficiency and life of the device are improved.

[0169] Compounds a, b and compounds 97, 77 are parallel comparative examples, the difference between them is that the N atom of the triarylamine in compounds 97 and 77 of the present invention is connected to 9-methyl-9-phenylfluorene, while the N atom of the triarylamine in the comparative compounds a and b is connected to 9,9-diphenylfluorene. The phenyl group at position 9 will reduce the mobility of the compound.

[0170] Compounds d, e and compounds 94, 104 are comparative examples, the difference between them is that: in compounds 94 and 104 of the present invention, the 9-methylfluorenyl group is bridged to the N atom of the triarylamine through a phenylene group, while in the comparative compounds d and e, the spirobifluorenyl group is directly bonded to the N atom of the triarylamine. Compared with the compounds in the present invention, the comparative compounds have two rigid and sterically hindered groups (spirobifluorenyl group and dibenzofuran group with substituents), which makes the configuration twisted too much, the fluidity is poor, and carrier traps are easily formed. Compounds 94 and 104 extend the system through the buffering of the phenylene group, enhance the molecular fluidity, and thus improve the luminous efficiency of the device.

[0171] Compound i and compound 127 are parallel comparative examples. The difference is that the comparative compound i has a benzene attached to the outside of dibenzofuran, while the present compound 127 has a triarylamine structure attached to the outside of dibenzofuran (dibenzofuran as a substituent on the triarylamine nitrogen atom, and the other two substituents are phenyl groups). This improves the injection effect, improves the hole transport efficiency, reduces the driving voltage, and can also make the configuration more distorted, improve the evaporation morphology, and extend the system to avoid the regionalization of carrier migration. When used in devices, it can reduce the hole transport energy barrier, improve the migration rate and luminous efficiency.

Claims

1. A luminescence auxiliary material, characterized in that: It has the structure shown in chemical formula I: In Chemical Formula I, X is independently selected from one of O, S, and C(CH3)2; R is selected from hydrogen, methyl, and benzene ring; Ar1 is selected from benzene ring, biphenyl, terphenyl; Ar2 and Ar3 are selected from any one of the following structures:

2. The luminescence auxiliary material according to claim 1, characterized in that Chemical formula I is shown below:

3. The luminescence auxiliary material according to claim 2, characterized in that Chemical formula I is selected from Chemical formula I-1 to Chemical formula I-12:

4. The luminescence auxiliary material according to claim 1, characterized in that The luminescence auxiliary material is selected from any one of the compounds represented by the following structural formulas:

5. A method for preparing the luminescence auxiliary material according to claim 1, characterized in that: The method specifically comprises the following steps: (1) Synthesis of Intermediate 1: 1.0 equivalent of raw material A, 1.0-1.2 equivalent of raw material B and 2.0 equivalent of sodium tert-butoxide were dissolved in toluene, and under nitrogen protection, 0.01-0.02 equivalent of tris(dibenzylideneacetone)dipalladium and 0.05 equivalent of tri-tert-butylphosphine were added, stirred evenly, heated to 100-120°C, and refluxed for 1-4 hours; the reaction was detected by thin layer chromatography. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered using diatomaceous earth to remove salt and catalyst. After the filtrate was cooled to room temperature, it was washed three times with water, and the organic phase was retained. The aqueous phase was then extracted with dichloromethane; after the organic phases were combined, the solvent was removed using a rotary evaporator; and intermediate 1 was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether with a volume ratio of 1:6; (2) Synthesis of Chemical Formula I: 1.0 equivalent of intermediate 1, 1.0-1.2 equivalents of raw material C and 2.0 equivalents of sodium tert-butoxide were dissolved in toluene, and under nitrogen protection, 0.01-0.02 equivalents of tris(dibenzylideneacetone)dipalladium and 0.05 equivalents of tri-tert-butylphosphine were added, stirred evenly, heated to 110-120°C, and refluxed for 8-12 hours; the reaction was detected by thin layer chromatography. After the reaction was completed, the temperature was slightly lowered, and diatomaceous earth was used for filtration to remove salt and catalyst. After the filtrate was cooled to room temperature, it was washed three times with water, and the organic phase was retained. The aqueous phase was then extracted with dichloromethane; after the organic phases were combined, the solvent was removed using a rotary evaporator; and the mixture was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether in a volume ratio of 1:8 to obtain Chemical Formula I; The specific synthetic route is as follows: in, R, Ar1-Ar3, and X are as defined in the chemical formula I of claim 1, and Hal1 and Hal2 are independently selected from chlorine and bromine.

6. Use of the luminescence auxiliary material according to claim 1 in preparing an organic electroluminescent device.

7. The use according to claim 6, characterized in that The organic electroluminescent device comprises a first electrode, a second electrode, and one or more organic layers disposed between the first electrode and the second electrode; and The organic layer includes at least one of a hole injection layer, a hole transport layer, an electron blocking layer, a luminescence auxiliary layer, a luminescent layer, a hole blocking layer, an electron transport layer, an electron injection layer and a capping layer; and, The luminescence auxiliary layer contains the luminescence auxiliary material.

8. Use of the luminescence auxiliary material according to claim 1 or the organic electroluminescent device according to claim 6 in preparing an organic electroluminescent device.

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