Organic light-emitting doping material, preparation method thereof, and organic electroluminescent device

Abstract

The present invention discloses an organic light-emitting doping material and a preparation method thereof and an organic electroluminescent device, and relates to the technical field of optoelectronic devices. The organic light-emitting doping material provided by the present invention has a structural formula of A The structure of the ligand changes some electrons and groups, changes the molecular space structure, improves the spin-orbit coupling effect of the luminescent molecule, makes it conducive to the generation of phosphorescence, enhances its quantum efficiency, and B By introducing a trifluoromethyl group into the dibenzofuran on the ligand and adding an aromatic group compound, the compound of the present invention can improve the intermolecular symmetrical dipole moment by adjusting the electrochemical properties of the compound, while also improving the phosphorescence quantum efficiency and electroluminescence efficiency of the material. Compared with the comparative example, the organic electroluminescent device prepared by using the compound of the present invention as the doping material for the light-emitting layer has a significantly lower driving voltage, and a significantly improved luminous efficiency and lifespan.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic devices, and in particular to an organic light-emitting doping material, a preparation method thereof, and an organic electroluminescent device. Background Art

[0002] OLED stands for Organic Light-Emitting Diode, also known as organic laser display or organic light-emitting semiconductor. OLED is a current-type organic light-emitting device that produces light through the injection and recombination of charge carriers. The intensity of the light is proportional to the injected current. Under the influence of an electric field, holes generated by the first electrode and electrons generated by the second electrode migrate, injecting into the hole transport layer and electron transport layer, respectively, and then migrating to the light-emitting layer. When the two meet in the light-emitting layer, energy excitons are generated, which excite the light-emitting molecules and ultimately produce visible light.

[0003] The most important factor determining the luminous efficiency of organic EL devices is the luminescent material. So far, fluorescent materials have been widely used as luminescent materials. However, given the electroluminescent mechanism, developing phosphorescent materials is theoretically one of the best approaches, as they can increase the luminous efficiency by up to four times compared to fluorescent substances. Organic electroluminescent materials (OLEDs), as a new generation of display technology, have the advantages of being ultra-thin, self-luminous, having a wide viewing angle, fast response, high luminous efficiency, good temperature adaptability, simple production process, low driving voltage, and low energy consumption. They have been widely used in industries such as flat panel displays, flexible displays, solid-state lighting, and automotive displays.

[0004] The light emitted by organic electroluminescent devices is divided into fluorescence and phosphorescence. Fluorescence is the light emitted by the energy of singlet excitons, while phosphorescence is the light emitted by the energy of both singlet and triplet excitons. Because the number of singlet and triplet states formed by excitons has a fixed ratio of 1:3, the theoretical maximum internal quantum efficiency of a fluorescent device utilizing only singlet excitons is only 25%, while the internal quantum efficiency of phosphorescent devices can reach 100%.

[0005] However, existing phosphorescent materials used in organic light-emitting devices have low efficiency and short lifespan. Therefore, how to provide an organic electroluminescent material with long lifespan, high efficiency and low driving voltage is an urgent problem to be solved by those skilled in the art.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] The purpose of the present invention is to provide an organic light-emitting doping material and a preparation method thereof and an organic electroluminescent device. The organic light-emitting doping material provided by the present invention can adjust different L AThe structure of the ligand changes some electrons and groups, changes the molecular space structure, improves the spin-orbit coupling effect of the luminescent molecule, makes it conducive to the generation of phosphorescence, and enhances its quantum efficiency. B By introducing a trifluoromethyl group and then an aromatic group into the dibenzofuran ligand, the team enhanced the degree of intermolecular conjugation, optimized the energy distribution of the HOMO and LOMO atoms, promoted charge separation and transport, and regulated the compound's electrochemical properties, improving the intermolecular symmetric dipole moment and simultaneously improving the material's phosphorescence quantum efficiency and electroluminescence efficiency. By altering the molecular spatial structure, regulating the compound's electrochemical properties, and improving the chemical symmetry and dipole moment of the structure, the resulting organic compound, when used in an organic electroluminescent device, reduces the device's startup voltage and increases the device's luminous efficiency and lifetime.

[0008] The present invention is achieved in that:

[0009] In a first aspect, the present invention provides an organic light-emitting dopant material having a structure as shown in Formula I:

[0010] Formula I;

[0011] X is O;

[0012] The R1-R8 are independently selected from any one of -H, -D, -T, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, substituted or unsubstituted C2-C18 alkyl, substituted or unsubstituted C3-C18 cycloalkyl, substituted or unsubstituted C6-C18 aryl and substituted or unsubstituted 4-18 membered heterocyclyl;

[0013] Ar1 is -CF3 and A combination of groups, m is 2, wherein the Ar4 is independently selected from a combination of any one of -F, -CH3, -CF3, -CH2F, -CHF2, -SiMe3, -GeMe3, a substituted or unsubstituted C2-C18 alkyl group, a substituted or unsubstituted C3-C18 cycloalkyl group, a substituted or unsubstituted C6-C18 aryl group and a substituted or unsubstituted 4-membered to 18-membered heterocyclic group, and any two bonds of Ar4 or any position of the ring cannot be fused, and q is an integer between 1 and 5;

[0014] The Ar2 is independently selected from any one of -H, -D, -T, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, -SiMe3, -GeMe3, substituted or unsubstituted C2-C18 alkyl, substituted or unsubstituted C6-C18 aryl and substituted or unsubstituted 4-18 membered heterocyclic group, and n is an integer between 0 and 2;

[0015] The Ar3 is independently selected from -H, -D, -T, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, -SiMe3, -GeMe3, substituted or unsubstituted C2-C18 alkyl, substituted or unsubstituted C3-C18 cycloalkyl, substituted or unsubstituted C6-C18 aryl, and p is an integer between 0-4.

[0016] In a second aspect, the present invention provides a method for preparing the organic light-emitting dopant material according to any one of the aforementioned embodiments, comprising the following steps:

[0017] The intermediate L with R1-R8 groups A It fully reacts with IrCl3•3H2O in the system of ethylene glycol ethyl ether and water to generate a bridged ligand of formula III;

[0018] The bridged ligand of formula III is then reacted with silver trifluoromethanesulfonate to form an intermediate of formula II having R1-R8 groups;

[0019] The intermediate II with R1-R8 groups and the intermediate L with Ar1-Ar3 B Fully reacting in an ethanol system to generate the organic light-emitting doping material;

[0020] Its synthetic route is as follows:

[0021] .

[0022] In a third aspect, the present invention provides an organic electroluminescent device comprising the organic light-emitting doping material according to any one of the aforementioned embodiments.

[0023] The present invention has the following beneficial effects:

[0024] The present invention adjusts different L A The structure of the ligand changes some electrons and groups, changes the molecular space structure, improves the spin-orbit coupling effect of the luminescent molecule, makes it conducive to the generation of phosphorescence, enhances its quantum efficiency, and at the same time B By introducing a trifluoromethyl group into the dibenzofuran on the ligand and adding an aromatic group compound, the compound of the present invention can improve the intermolecular symmetrical dipole moment by adjusting the electrochemical properties of the compound, while also improving the phosphorescence quantum efficiency and electroluminescence efficiency of the material. As a result, the compound of the present invention is used as a doping material for the light-emitting layer. Compared with the organic electroluminescent device prepared in the comparative example, the driving voltage of the organic electroluminescent device prepared therefrom is significantly reduced, and the luminous efficiency and life are significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 This is the NMR spectrum of the compound of structural formula Ⅰ-237. DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0028] The present invention provides an organic light-emitting dopant material having a structure as shown in Formula I:

[0029] Formula I;

[0030] X is O;

[0031] R1-R8 are independently selected from any one of -H, -D, -T, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, substituted or unsubstituted C2-C18 alkyl, substituted or unsubstituted C3-C18 cycloalkyl, substituted or unsubstituted C6-C18 aryl and substituted or unsubstituted 4-18 membered heterocyclyl; the substitution in the substitution or unsubstituted in R1-R8 refers to one or more of -D, -T, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2 and -SiMe3;

[0032] Ar1 is -CF3 and A combination of groups, m is 2, wherein Ar4 is independently selected from a combination of any one of -F, -CH3, -CF3, -CH2F, -CHF2, -SiMe3, -GeMe3, a substituted or unsubstituted C2-C18 alkyl group, a substituted or unsubstituted C3-C18 cycloalkyl group, a substituted or unsubstituted C6-C18 aryl group, and a substituted or unsubstituted 4-membered to 18-membered heterocyclic group, and any two bonds of Ar4 or any position of the ring cannot be fused, and q is an integer between 1 and 5; the substitution in the substitution or unsubstitution in Ar4 refers to: one or more of -F, -CN, -CH3, -CF3, -CH2F, -CHF2, -SiMe3 and -GeMe3;

[0033] Ar2 is independently selected from any one of -H, -D, -T, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, -SiMe3, -GeMe3, a substituted or unsubstituted C2-C18 alkyl group, a substituted or unsubstituted C6-C18 aryl group, and a substituted or unsubstituted 4- to 18-membered heterocyclic group, and n is an integer between 0 and 2; the substitution in the substitution or unsubstitution in Ar2 refers to one or more of -D, -T, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, and -SiMe3;

[0034] Ar3 is independently selected from -H, -D, -T, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, -SiMe3, -GeMe3, substituted or unsubstituted C2-C18 alkyl, substituted or unsubstituted C3-C18 cycloalkyl, substituted or unsubstituted C6-C18 aryl, p is an integer between 0 and 4; the substitution in the substitution or unsubstitution in Ar3 refers to: one or more of -D, -T, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2 and -SiMe3;.

[0035] The heteroatoms in the heterocyclic groups in Ar4, Ar2 and Ar3 are independently selected from one or more of N, O and S.

[0036] Formula I of the present invention has at least one of the following four specific structural formulas:

[0037]

[0038] ;

[0039] Wherein: R1-R8 and Ar1, Ar2, Ar3, Ar4 are the same as above.

[0040] In some embodiments, R1-R8 are independently selected from the following groups: -H, -D, -T, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, thiolane, phenyl, biphenyl, deuterated phenyl, deuterated phenyl, terphenyl, naphthyl, fluorenyl, phenanthrenyl, anthracenyl, indenyl, triphenylene, pyrenyl, tetraphenyl, perylene, chrysene, fused tetraphenyl, fluoranthenyl, furanyl, thienyl, imidazole, thiophene, thiophene, pyrene, tetraphenyl, pyrene, pyrene, tetraphenyl, fluoranthenyl, furanyl, thiophene, pyrene ... oxazolyl, pyrazolyl, thiazolyl, thiadiazolyl, isothiazolyl, triazinyl, tetrazinyl, triazolyl, tetrazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, benzofuranyl, benzothiophenyl, isobenzofuranyl, dibenzofuranyl, dibenzothiophenyl, benzimidazolyl, benzothiazolyl, benzisothiazolyl, benzisoxazolyl, benzoxazolyl, isoindolyl, indolyl, indazolyl, benzothiadiazolyl, quinolyl, isoquinolyl, cinnolinyl, quinazolinyl, quinoxalinyl, carbazolyl, phenanthridinyl and benzodioxolyl;

[0041] and / or, Ar2 is selected from the following groups: -H, -D, -T, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, -SiMe3, -GeMe3, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, tetrahydrofuran, pyrrolidine, thiolane, tetrahydropyran, phenyl, biphenyl, deuterated phenyl, deuterated phenyl, terphenyl, naphthyl, fluorenyl, phenanthrenyl, anthracenyl, indenyl, triphenylene, pyrenyl, naphthacene, perylene, chrysene, condensed tetraphenyl, fluoranthenyl, furyl, thienyl, pyrrolyl, imide oxazolyl, pyrazolyl, thiazolyl, thiadiazolyl, isothiazolyl, isoxazolyl, oxazolyl, oxadiazolyl, triazinyl, tetrazinyl, triazolyl, tetrazolyl, furazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, benzofuranyl, benzothiophenyl, isobenzofuranyl, dibenzofuranyl, dibenzothiophenyl, benzimidazolyl, benzothiazolyl, benzisothiazolyl, benzisoxazolyl, benzoxazolyl, isoindolyl, indolyl, indazolyl, benzothiadiazolyl, quinolyl, isoquinolyl, cinnolinyl, quinazolinyl, quinoxalinyl, carbazolyl, phenoxazinyl, phenanthridinyl and benzodioxole;

[0042] and / or, Ar3 is selected from the following groups: -H, -D, -T, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, -SiMe3, -GeMe3, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, phenyl, biphenyl, deuterated phenyl, dideuterated phenyl, terphenyl, naphthyl, fluorenyl, phenanthrenyl, anthracenyl, indenyl, pyrenyl, naphthacene, perylenyl, chrysene, fused tetraphenyl and fluoranthenyl, or a combination of multiple groups;

[0043] And / or, Ar4 is selected from the following groups: -F, -CN, -CH3, -CF3, -CH2F, -CHF2, -SiMe3, -GeMe3, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, thiolane, phenyl, biphenyl, terphenyl, naphthyl, fluorenyl, phenanthrenyl, anthracenyl, indenyl, triphenylene, pyrenyl, naphthacene, perylene, chrysene, fused tetraphenyl, fluoranthene, furyl, thienyl, pyridyl, pyrimidinyl, benzofuranyl, benzothienyl, isobenzofuranyl, dibenzofuranyl and dibenzothienyl. One or a combination of multiple groups.

[0044] Specifically, the organic light-emitting doping material of the present invention has at least one of the specific structures shown in the following formula:

[0045] .

[0046] In addition, the present invention also provides a method for preparing the above-mentioned organic light-emitting doping material, which comprises the following steps:

[0047] S1, intermediate L with R1-R8 groups A It fully reacts with IrCl3•3H2O in the system of ethylene glycol ethyl ether and water to generate a bridged ligand of formula III;

[0048] S2, the bridging ligand of formula III is then reacted with silver trifluoromethanesulfonate to form an intermediate of formula II with R1-R8 groups;

[0049] S3, intermediate II with R1-R8 groups and intermediate L with Ar1-Ar3 B Fully reacting in an ethanol system to generate the organic light-emitting doping material;

[0050] Its synthetic route is as follows:

[0051] .

[0052] The present invention also provides an organic electroluminescent device comprising the aforementioned organic light-emitting dopant material. Specifically, the organic electroluminescent device comprises a first electrode, a hole transport region, a light-emitting layer, an electron transport region, and a second electrode, arranged in sequence. The light-emitting layer is prepared from the aforementioned organic light-emitting dopant material.

[0053] A substrate can be used below the first electrode or above the second electrode. The substrate is made of glass or a polymer material with excellent mechanical strength, thermal stability, water resistance, and transparency. In addition, the substrate used as a display can also be provided with a thin film transistor (TFT).

[0054] The first electrode can be formed by sputtering or depositing the material used as the first electrode on the substrate. When the first electrode serves as an anode, transparent conductive oxide materials such as indium tin oxide (ITO), indium zinc oxide (IZO), tin dioxide (SnO2), zinc oxide (ZnO) and any combination thereof can be used. In addition, the anode material can also be selected from materials and combinations thereof that facilitate hole injection other than the listed anode materials, including materials known to be suitable for anodes. When the first electrode serves as a cathode, metals or alloys such as magnesium (Mg), silver (Ag), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver (Mg-Ag) and any combination thereof can be used. In addition to the cathode materials listed above, the cathode material can also be a material and a combination thereof that facilitates electron injection, including materials known to be suitable for cathodes.

[0055] The hole transport region, the light-emitting layer, and the electron transport region collectively serve as an organic material layer, which is located between the first electrode and the second electrode. The organic material layer can be formed on the electrode by vacuum thermal evaporation, spin coating, printing, and the like. The compound used as the organic material layer can be an organic small molecule, an organic macromolecule, a polymer, and a combination thereof. The hole transport region is located between the anode and the light-emitting layer. The hole transport region can be a hole transport layer (HTL) of a single-layer structure, including a single-layer hole transport layer containing only one compound and a single-layer hole transport layer containing multiple compounds. The hole transport region can also be a multilayer structure including at least one layer of a hole injection layer (HIL), a hole transport layer (HTL), and an electron blocking layer (EBL).

[0056] The material of the hole transport layer can be selected from, but not limited to, phthalocyanine derivatives such as CuPc, conductive polymers or polymers containing conductive dopants such as polyphenylene ethylene, polyaniline / dodecylbenzenesulfonic acid (PANI / DBSA), poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonate) (PEDOT / PSS), polyaniline / camphorsulfonic acid (PANI / CSA), polyaniline / poly(4-styrenesulfonate) (PANI / PSS), aromatic amine derivatives such as the compounds shown in HT-1 to HT-34 below; or any combination thereof.

[0057] , but not limited to the above materials.

[0058] The hole injection layer is located between the anode and the hole transport layer. The hole injection layer can be a single compound material or a combination of multiple compounds. For example, the hole injection layer can use one or more compounds from HT-1 to HT-34 above, or one or more compounds from HI-1 to HI-3 below. Alternatively, one or more compounds from HT-1 to HT-34 can be doped with one or more compounds from HI-1 to HI-3 below:

[0059] , but not limited to the above materials.

[0060] The light-emitting layer may include a luminescent dye (i.e., a dopant) that can emit light at different wavelengths, and may also include a host material. The light-emitting layer may be a monochromatic light-emitting layer that emits a single color, such as red, green, or blue. Multiple monochromatic light-emitting layers of different colors may be arranged in a planar pattern according to a pixel pattern, or they may be stacked together to form a multi-color light-emitting layer. When light-emitting layers of different colors are stacked together, they may be separated from each other or connected to each other. The light-emitting layer may also be a single-color light-emitting layer that can simultaneously emit different colors, such as red and green.

[0061] Depending on the technology, the luminescent layer material can include phosphorescent electroluminescent materials, thermally activated delayed fluorescent materials, and other materials. An OLED device can employ a single luminescence technology or a combination of multiple technologies. These different luminescent materials, categorized by technology, can emit the same or different colors of light.

[0062] The compound of formula I of the present invention is used as a doping material in the light-emitting layer.

[0063] The electron transport region can be a single-layer electron transport layer (ETL), including a single-layer electron transport layer containing only one compound and a single-layer electron transport layer containing multiple compounds. The electron transport region can also be a multi-layer structure including at least one of an electron injection layer (EIL), an electron transport layer (ETL), and a hole blocking layer (HBL).

[0064] The electron transport layer material may be selected from, but not limited to, one or more combinations of ET-1 to ET-57 listed below.

[0065] .

[0066] But it is not limited to the above materials.

[0067] The device may further include an electron injection layer located between the electron transport layer and the cathode. The electron injection layer material includes but is not limited to one or more combinations of the following: LiF, NaCl, CsF, Li2O, Cs2CO3, BaO, Na, Li, and Ca.

[0068] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0069] Compound Example 1

[0070] This compound embodiment provides an organic light-emitting doping material I-237, namely, a compound numbered I-237. The specific synthesis steps are as follows:

[0071] (1) L B -237 is not an existing technology and needs to be synthesized in one step to synthesize L B -237 The steps are as follows:

[0072]

[0073] Under nitrogen protection, 6-bromo-3-(trifluoromethyl)dibenzo[b,d]furan (CAS: 2833655-79-9) (1.0 eq), diboronic acid pinacol ester (1.5 eq), X-Phos (0.12 eq), palladium acetate (0.02 eq), potassium acetate (3 eq) and dioxane were added to the reaction system in sequence. N2 was replaced three times and N2 protection was applied. The mixture was heated and stirred at 100°C overnight. After the reaction was completed, the mixture was filtered through celite and anhydrous magnesium sulfate, washed twice with ethyl acetate, and the organic phase was collected and concentrated under reduced pressure to obtain a crude product intermediate of formula L BⅢ -237 was used directly in the next step.

[0074]

[0075] Under nitrogen protection system, weigh compound 2-bromopyridine (CAS: 109-04-6) (1.0eq), intermediate formula L BⅢ -237 (1.2 eq) and anhydrous potassium carbonate (3.0 eq) were placed in the reaction system, and toluene, anhydrous ethanol, and purified water were added. Pd (PPh3)4 (0.02 eq) was added under nitrogen protection. After the addition was completed, the mixture was refluxed at 100°C for 24 hours under nitrogen protection, and then cooled to 25°C. After the reaction was cooled, the mixture was extracted with ethyl acetate, washed three times with saturated brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The crude product was subjected to column chromatography (200-300 mesh, 600 g) with a developing agent of EA:PE = 1:10 to remove impurities. The receiving solution was vortexed until no liquid flowed out and dried under vacuum to obtain the intermediate compound L shown. BⅡ -237 (yield 59%), its HPLC purity was greater than 99.5%.

[0076] Mass spectrometry test value: 313.26.

[0077]

[0078] Under nitrogen protection system, weigh compound intermediate L BⅡ -237 (1.0 eq), tetrahydrofuran, start stirring under nitrogen protection, cool to -78 degrees Celsius, add LDA (1.5 eq) dropwise, keep stirring for 2 hours, add iodine (1.0 eq), naturally warm to room temperature and react for 14 hours. After the reaction is completed, separate the organic phase, extract, dry, column chromatography, and spin dry the solvent to obtain the intermediate compound L shown in FIG. BⅠ -237 (yield 68%), its HPLC purity was greater than 99.5%.

[0079] Mass spectrometry test value: 439.26.

[0080]

[0081] Under nitrogen protection system, weigh compound intermediate L BⅠ -237 (1.0 eq), 4-biphenylboronic acid (CAS: 5122-94-1) (1.1 eq), and anhydrous potassium carbonate (3.0 eq) were placed in the reaction system, and toluene, anhydrous ethanol, and purified water were added. Pd (PPh3)4 (0.02 eq) was added under nitrogen protection. After the addition was completed, the mixture was refluxed at 100°C for 24 hours under nitrogen protection, and then cooled to 25°C. After the reaction was cooled, the mixture was extracted with ethyl acetate, washed three times with saturated brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The crude product was subjected to column chromatography (200-300 mesh, 700 g) with a developing solvent of EA:PE = 1:13 to remove impurities. The receiving solution was vortexed until no liquid flowed out and dried under vacuum to obtain the intermediate compound L shown. B -237 (yield 59%), its HPLC purity was greater than 99.5%.

[0082] Mass spectrometry test value: 465.36.

[0083] (2) Synthesis of I-237.

[0084]

[0085] Under nitrogen protection system, weigh the ligand L AⅢ-237 (5-methyl-2-phenylpyridine) (CAS: 3256-88-0) (2.5 eq) and IrCl₃·3H₂O (1.0 eq) were placed in a reaction system, and a mixture of ethylene glycol ethyl ether and purified water was added. The mixture was refluxed under nitrogen for 28 hours, then cooled to room temperature. A precipitate formed, which was filtered, rinsed with water, anhydrous ethanol, and then dried with petroleum ether. This afforded the bridged ligand III-237 (59% yield).

[0086]

[0087] Weigh 1.0 eq of intermediate III-237, add 2.5 eq of silver trifluoromethanesulfonate, then add dichloromethane and methanol. Reflux under nitrogen for 26 hours, cool to room temperature, and concentrate the filtrate by column chromatography (short column) until a solid precipitates. The iridium complex intermediate II-237 shown is obtained (yield 90%).

[0088]

[0089] Weigh the intermediate formula II-237 (1.0eq), add the ligand formula L B -237 (2.5 eq), then anhydrous ethanol was added to the system, refluxed under nitrogen for 36 hours, filtered, washed with ethanol, and dried. Using dichloromethane as the solvent, silica gel column chromatography was performed, and the filtrate was concentrated to precipitate a solid to obtain the final compound shown in Formula I-237 (yield 29%).

[0090] The organic light-emitting doping material I-237 was subjected to the following analysis and tests:

[0091] HPLC purity: greater than 99.5%;

[0092] The mass spectrometry test value was 993.49.

[0093] Elemental analysis: Calculated values ​​for C, 65.31; H, 3.76; F, 5.74; N, 4.23; O, 1.61. Found values ​​for C, 65.33; H, 3.78; F, 5.73; N, 4.22; O, 1.64.

[0094] The H NMR spectrum of compound I-237 is attached. Figure 1 .

[0095] The synthesis methods of other compounds are the same as those described above and are not described in detail here.

[0096] Device Example 1

[0097] Compound I-1 prepared in the present invention was selected as a phosphorescent material with a doping concentration of 5% to prepare an OLED device. The specific preparation method is as follows:

[0098] (1) A glass plate coated with an ITO transparent conductive layer was ultrasonically treated in a commercial cleaning agent, rinsed in deionized water, ultrasonically degreased in a mixed solvent of acetone:ethanol (volume ratio 1:1), baked in a clean environment until the water was completely removed, cleaned with ultraviolet light and ozone, and bombarded with a low-energy cation beam;

[0099] (2) Place the glass substrate with the anode in a vacuum chamber and evacuate to 1×10 -5 ~9×10 -3 Pa, vacuum evaporation HI-1 as a hole injection layer on the above-mentioned anode layer film at a deposition rate of 0.1 nm / s, with a total deposition thickness of 10 nm; then evaporation of the first hole layer HT-1 at a deposition rate of 0.1 nm / s to a thickness of 60 nm; then evaporation of the electron blocking layer EB-1 at a deposition rate of 0.1 nm / s to a thickness of 5 nm;

[0100] (3) Vacuum evaporating an EML on the hole transport layer as the light-emitting layer of the device. The EML includes a host material GH-1 and a dopant material I-1 of the present invention, with a doping concentration of 5% by mass, to form an organic light-emitting layer of the device. The evaporation rate is 0.2 nm / s, and the total film thickness is 30 nm.

[0101] (4) ET-1:QLi with a mass ratio of 1:1 was evaporated on the hole blocking layer as the electron transport material of the device electron transport layer. The evaporation rate was 0.1 nm / s and the total film thickness was 30 nm.

[0102] (5) LiF with a thickness of 1 nm was vacuum-evaporated onto the electron transport layer as an electron injection layer, and an Al layer with a thickness of 150 nm was deposited as the device cathode. After packaging, an OLED device was obtained. The performance and luminescence characteristics of the resulting device were tested using a Keithley 2400 source measurement unit and a CS-2000 spectroradiometer to evaluate the driving voltage, lifetime, and luminous efficiency.

[0103] The structure used is as follows:

[0104]

[0105] Device Example 2-80

[0106] Referring to the method of the device embodiment 1, the only difference is that the doping material I-1 is replaced by I-2, I-3, I-15, I-17, I-18, I-19, I-31, I-32, I-33, I-34, I-35, I-36, I-80, I-81, I-93, I-95, I-96, I-97, I-109, I-110, I-111, I-112, I-113, I-114, I-158, I-159, I-171, I-173, I-174, I-175, I-187, I-188, I-189, I-190, I-191, I-192, I-197, I-198, I- 210, I-212, I-213, I-214, I-226, I-227, I-228, I-229, I-230, I-231, I-236, I-237, I-249, I-251, I-252, I-253, I-265, I-266, I-267, I-268, I-269, I-270, I-328, I-472, I-473, I-474, I-478, I-479, I-480, I-547, I-548, I-549, I-550, I-551, I-552, I-604, I-606, I-662, I-663, I-665, I-666.

[0107] Device Comparison Examples 1-36

[0108] An organic electroluminescent device was prepared in the same manner as in Device Example 1, except that the doping compound I-1 in Device Example 1 was replaced by the structural compounds of Comparative Examples 1-36, respectively.

[0109]

[0110] The prepared organic electroluminescent device was subjected to the same test as in Example 1. The results are shown in Table 1.

[0111] Experimental example

[0112] The driving voltage, luminous efficiency, and lifespan of the organic electroluminescent devices obtained from the above device examples and the device comparative examples were characterized at a brightness of 8000 (nits). The test results are shown in Table 1 below:

[0113]

[0114] By comparing the comparative example compounds 1-36 with the organic light-emitting doping materials of the present invention, it can be seen that L B The ligand introduces a trifluoromethyl group into dibenzofuran and an aromatic group into the ring to which the trifluoromethyl group is connected. Thus, compared with the comparative example compound, the electrochemical properties of the compound of the present invention are adjusted, the intermolecular symmetrical dipole moment is improved, and the phosphorescence quantum efficiency and electroluminescence efficiency of the material are improved. Therefore, when the compound of the present invention is used as a doping material for the light-emitting layer, the organic electroluminescent device prepared therefrom has a significantly lower driving voltage, and the luminous efficiency and life are improved compared with the organic electroluminescent device prepared in the comparative example.

[0115] By comparing the comparative example compounds 1-36 with the organic light-emitting doping materials of the present invention, it can be seen that by adjusting different L A The structure of the ligand changes some electrons and groups, etc., changes the molecular spatial structure, improves the spin-orbit coupling effect of the luminescent molecule, makes it conducive to the generation of phosphorescence, enhances its quantum efficiency, and makes the compound of the present invention used as a doping material for the light-emitting layer. The organic electroluminescent device prepared therefrom has a significantly lower driving voltage, and the luminous efficiency and life are improved compared with the organic electroluminescent device prepared in the comparative example, and these figures are all beyond any value attributable to experimental errors.

[0116] Among them, the comparative compound 31 is compared with the example compounds Ⅰ-1, Ⅰ-2, and Ⅰ-3 of the present invention respectively. By changing the combination of substituents on the dibenzofuran ring, the deuterated phenyl group is replaced with p-methylbenzene, p-tert-butylbenzene, and biphenyl, respectively, thereby improving the symmetrical dipole moment of the material, making it have better spatial twisting ability, making it more conducive to the generation of phosphorescence, and at the same time improving the intramolecular charge transfer effect, narrowing the energy level difference between the molecular ground state and the excited state, so that the compound of the present invention is used as a doping material for the light-emitting layer. The organic electroluminescent device prepared by the compound has a significantly lower driving voltage than the organic electroluminescent device prepared by the comparative example, and the luminous efficiency and life are both improved.

[0117] Among them, comparative example compound 12 and comparative example compound 33 are compared with the example compounds Ⅰ-80, Ⅰ-81 and Ⅰ-236, Ⅰ-237 of the present invention respectively.A The ligands are exactly the same, only L is changed B The combination of ligands, after replacing D in the comparative example compound with p-tert-butylbenzene and biphenyl, respectively, significantly enhances the degree of conjugation of the molecule, while optimizing and adjusting the HOMO and LUMO energy level distributions, promoting charge separation and transport, so that the organic electroluminescent device prepared by using the compound of the present invention as a doping material for the light-emitting layer has a significantly lower driving voltage, and the luminous efficiency and life are improved compared with the organic electroluminescent device prepared in the comparative example.

[0118] The above embodiment only lists the effect data of devices made with a part of the structural formula. This is a representative sampling test. According to the experimental data, the overall data is not much different and can represent the effects of other unlisted structures.

[0119] The present invention adjusts different L A The structure of the ligand changes some electrons and groups, changes the molecular space structure, improves the spin-orbit coupling effect of the luminescent molecule, makes it conducive to the generation of phosphorescence, enhances its quantum efficiency, and at the same time B By introducing a trifluoromethyl group into the dibenzofuran on the ligand and adding an aromatic group compound, the compound of the present invention is compared with the comparative example compound, by adjusting the electrochemical properties of the compound, improving the intermolecular symmetrical dipole moment, and simultaneously improving the phosphorescence quantum efficiency and electroluminescence efficiency of the material. As a result, the compound of the present invention is used as a doping material for the light-emitting layer. Compared with the organic electroluminescent device prepared in the comparative example, the driving voltage of the organic electroluminescent device prepared therefrom is significantly reduced, and the luminous efficiency and life are significantly improved.

[0120] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. An organic light-emitting doping material, characterized in that: It has a structure as shown in Formula II to Formula III: ； The X is O; q is an integer between 1 and 5; n is an integer between 0 and 2; p is an integer between 0 and 4; The R1-R8 is selected from the following groups: one or more groups selected from -H, -D, -CD3, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, phenyl, deuterated phenyl; The Ar2 is selected from the following groups: -H, CH3; Ar3 is selected from the following groups: -H, -D, -CD3, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, phenyl, deuterated phenyl, one or more groups in combination; The Ar4 is selected from the following groups: one group or a combination of multiple groups of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, phenyl, biphenyl, and naphthyl.

2. An organic light-emitting doping material, characterized in that: The organic light-emitting doping material has at least one of the specific structures shown in the following formula: 。 3. An organic electroluminescent device, characterized in that: It comprises the organic light-emitting doping material according to any one of claims 1 to 2.

4. The organic electroluminescent device according to claim 3, characterized in that: It comprises a first electrode, a hole transport region, a light-emitting layer, an electron transport region and a second electrode which are arranged in sequence. The light-emitting layer is made of the organic light-emitting doping material.

5. The organic electroluminescent device according to claim 4, characterized in that: The hole transport region includes at least one of a hole injection layer, a hole transport layer, and an electron blocking layer.

6. The organic electroluminescent device according to claim 5, characterized in that: The electron transport region includes at least one of an electron injection layer, an electron transport layer, and a hole blocking layer.

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