Organic electroluminescent material and luminescent device

Abstract

The invention belongs to the field of organic electroluminescence, and provides an organic electroluminescent material and an organic electroluminescent device containing the same. The structural general formula of the organic electroluminescent material is shown in the specification. The compound disclosed by the invention is regulated and controlled by an LA ligand, the planarity is enhanced by adjusting electron groups and molecular configuration, and the intermolecular accumulation effect and non-radiative energy loss are reduced, so that the luminous efficiency and the device stability are improved. LB ligand change: a nitrogen-containing heterocyclic ring structure is introduced into a dibenzofuranopyridine skeleton, and the following advantages are realized by utilizing unique electronic characteristics of the nitrogen-containing heterocyclic ring structure: HOMO / LUMO energy level matching is optimized, and the charge injection potential barrier is reduced; effective utilization of triplet excitons is promoted; and exciton quenching and non-radiative transition are inhibited. The compound is used as a light-emitting layer doping material, the driving voltage of the prepared organic electroluminescent device is obviously reduced, the light-emitting efficiency is obviously improved, and the service life is obviously prolonged.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic device technology, and relates to an organic electroluminescent material and a light-emitting device. Background Technology

[0002] Organic light-emitting diodes (OLEDs) are electroluminescent devices based on organic semiconductor materials. They work by using an electric field to drive carrier injection and recombination to emit light. OLEDs can be classified into single-layer, double-layer, triple-layer, and multi-layer devices based on their structure. Multi-layer structures offer the greatest advantage because they allow for precise control of the function of each layer (such as charge transport and light emission), thereby improving luminous efficiency, color performance, and device lifespan. This design flexibility enables OLEDs to be widely used in mobile phones, televisions, and flexible displays.

[0003] The core of organic electroluminescent (EL) devices is the emitting layer, and the most critical factor determining their efficiency is the exciton utilization capability of the emitting material. The radiative decay process of excitons directly affects the internal quantum efficiency (IQE) of the device. Currently, the emitting materials for organic EL devices have mainly undergone two generations of development: The first generation: fluorescent materials, which only utilize singlet excitons for radiative emission. Due to spin statistics, only 25% of excitons can be utilized, therefore, the maximum internal quantum efficiency (IQE) is ≤25%. The second generation of phosphorescent materials, which are now widely used, enhances spin-orbit coupling (SOC) by introducing heavy metal atoms (such as Ir, Pt, etc.), enabling the non-emitting triplet excitons (T1) to radiate and transition. It can utilize both singlet and triplet excitons (S1+T1), thus achieving an IQE of up to 100%, which can significantly improve efficiency.

[0004] However, existing phosphorescent materials used in organic light-emitting devices suffer from low efficiency and short lifespan. Therefore, providing an organic electroluminescent material with long lifespan, high efficiency, and low driving voltage is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide an organic electroluminescent material and a light-emitting device. The organic electroluminescent material provided by the present invention is used as a dopant in organic electroluminescent devices. It employs a compound with a specific structure, which enhances molecular planarity and reduces stacking and non-radiative decay by introducing an N-heterocyclic structure into dibenzofuranopyridine, thereby improving luminous efficiency and device stability. The N-heterocyclic structure optimizes the HOMO / LUMO energy level matching, lowers the exciton injection barrier and turn-on voltage; simultaneously, it promotes triplet exciton formation, reduces exciton annihilation and non-radiative transitions, ultimately achieving the goals of lower driving voltage, higher efficiency, and longer lifetime for OLED devices.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] An organic electroluminescent material, wherein the organic electroluminescent material has the general formula of a compound with the structure shown in Formula I: Ir(L A )2(L B );

[0008] Among them, L A and L B All are ligands, each possessing a CN-like diptery structure;

[0009]

[0010] Among them, L A and L B Both are ligands, each possessing a bidentate structure of CN:

[0011]

[0012] m and p are integers between 0 and 3, n is an integer between 0 and 2, and q is an integer between the ring with no substitution and the maximum substitution value.

[0013] The R1, R2, R3, R4, R5, R6, R7, R8, Ar1, Ar2, Ar 3， Ar4, Ar1, Ar2, Ar3, and Ar4 are each independently selected from -H, -D, -T, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, -SiMe3, -GeMe3, substituted or unsubstituted C2-C. 18 Alkyl, substituted or unsubstituted C3-C 18 cycloalkyl, substituted or unsubstituted C6-C 18 Any one of aryl and substituted or unsubstituted 4- to 18-membered heterocyclic groups;

[0014] Each Ar1, Ar2, Ar3, and Ar4 may be the same or different;

[0015] Ring A can be any of the substituted or unsubstituted N-containing 3- to 18-membered heterocyclic groups.

[0016] If there is only one heteroatom in the heterocycle, it must be N; if there are two or more, one of them is N and the other is one or more of N, O, and S, and the N in the heteroatom is connected to the ring in which it is located.

[0017] In Formula I, ring A contains a nitrogen atom, and the nitrogen atom is chemically bonded to the pyridine ring; ring A can be an aromatic or non-aromatic structure.

[0018] Ring B shares two carbon atoms with ring A, and the number of rings B is 0, 1, or 2.

[0019] When the number of ring B is 0, that is, ring B is hydrogen;

[0020] When the number of ring B is not zero, the ring Bs are the same or different, and the ring Bs are independently selected from any one of C4-C6 cycloalkyl, substituted or unsubstituted C4-C6 aryl and substituted or unsubstituted 4-6 heterocyclic groups.

[0021] X is independently selected from one of NR′, O, S, Si R′R″, Ge R′R″, CR′R″, and Se;

[0022] Wherein, R′ and R″ are each independently selected from -H, -D, -T, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, -SiMe3, -GeMe3, substituted or unsubstituted C2-C 18 Alkyl, substituted or unsubstituted C3-C 18 cycloalkyl, substituted or unsubstituted C6-C 18 Any one of aryl and substituted or unsubstituted 4-18 member heterocyclic groups.

[0023] It should be noted that, in this invention, the number of carbon atoms in ring B excludes the number of carbon atoms conjugated with ring A. For example, when two rings B and ring A form a carbazole structure, ring B is defined as a C4 aryl group according to this invention.

[0024] According to one embodiment of the present invention, R1-R8 and Ar1-Ar4 in the substituent groups can each independently form substituted or unsubstituted C3-C groups with other substituents on the ring. 20 Aliphatic rings, substituted or unsubstituted C6-C 20 Aromatic ring, substituted or unsubstituted C4-C 20 Aromatic heterocyclic, substituted or unsubstituted C 10 -C 20 Fused ring.

[0025] According to one embodiment of the present invention, the substituents on the substituent group are at least selected from one or more of -H, -D, -T, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, -SiMe3, and -GeMe3.

[0026] According to one embodiment of the present invention, the heteroatom in the heterocyclic group is one or more of N, O, S, Si, and Ge.

[0027] According to one embodiment of the invention, the hydrogen in the group is not replaced by deuterium, or is wholly or partially replaced by deuterium.

[0028] According to one embodiment of the present invention, R1-R8 and Ar1-Ar4 are each independently 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, pyrrolidone, thiacyclopentane, tetrahydropyran, phenyl, biphenyl, deuterated phenyl, bideuterated phenyl, terphenyl, naphthyl, fluorenyl, phenanthryl, anthracene, indene, triphenylene, pyrene, tetraphenyl, peryl, trefoil, condensed tetraphenyl, fluoranyl, The following groups and their combinations include: furanyl, thiopheneyl, pyrroleyl, imidazolyl, pyrazolyl, thiazolyl, thiadiazolyl, isothiazolyl, isoxazolyl, oxazolyl, oxadiazolyl, triazinyl, tetraazinyl, triazolyl, tetraazolyl, furazolyl, pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl, benzofuranyl, benzothiopheneyl, isobenzofuranyl, dibenzofuranyl, dibenzothiopheneyl, benzimidazolyl, benzothiazolyl, benzoisothiazolyl, benzoisooxazolyl, benzooxazolyl, isoindolyl, indolyl, inzolyl, benzothiadiazolyl, quinolinyl, isoquinolinyl, cenolinyl, quinazolinyl, quinoxolinyl, carbazoleyl, phenoxazinyl, phenanthidyl, benzo-m-dioxacyclopentenyl, etc.

[0029]

[0030] According to one embodiment of the present invention, ring A is a 5-membered heterocyclic ring or a 6-membered heterocyclic ring;

[0031] According to one embodiment of the present invention, the organic light-emitting material is selected from compounds having the following general formula:

[0032]

[0033] Where Y represents C, N, O, S, Si, or Ge;

[0034] --- indicates a double bond that is optional.

[0035] According to one embodiment of the present invention, the organic light-emitting material is selected from compounds having the following general formula:

[0036]

[0037] The definition of ring D is the same as that of ring B;

[0038] Where Y is independently selected from one of NR′, O, S, Si R′R″, Ge R′R″, CR′R″ and Se; R′ and R″ are defined as described above;

[0039] --- indicates a double bond that is optional.

[0040] According to one embodiment of the present invention, the organic light-emitting material is selected from compounds having the structure shown in the following formula:

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

[0082] According to one embodiment of the present invention, the preparation process of the compound with the structure shown in Formula I is as follows:

[0083]

[0084] The limitations in the above formula are the same as those mentioned above, and will not be repeated here.

[0085] According to the present invention, an organic electroluminescent device is also provided, the organic electroluminescent device comprising an anode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, an electron transport layer, an electron injection layer and a cathode arranged sequentially.

[0086] Generally, an organic electroluminescent device includes a first electrode and a second electrode, as well as an organic material layer located between the electrodes. This organic material can be further divided into multiple regions. For example, the organic material layer may include a hole transport region, a light-emitting layer, and an electron transport region.

[0087] In a specific embodiment, a substrate may be used below the first electrode or above the second electrode.

[0088] Preferably, the substrates are made of glass or polymer materials with excellent mechanical strength, thermal stability, water resistance, and transparency. Furthermore, the substrate used for a display may also contain thin-film transistors (TFTs).

[0089] Specifically, the first electrode can be formed by sputtering or depositing a material used as the first electrode on a substrate. When the first electrode is used as the anode, it can be a transparent conductive oxide material such as indium tin oxide (ITO), indium zinc oxide (IZO), tin dioxide (SnO2), zinc oxide (ZnO), or any combination thereof. Furthermore, the anode material can also be selected from materials and combinations thereof that facilitate hole injection, in addition to the anode materials listed above, including known materials suitable for anodes. When the first electrode is used as the cathode, it can be a metal or alloy such as magnesium (Mg), silver (Ag), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver (Mg-Ag), or any combination thereof. Besides the cathode materials listed above, the cathode material can also be a material and combination thereof that facilitates electron injection, including known materials suitable for cathodes.

[0090] According to one embodiment of the present invention, the organic material layer can be formed on the electrode by methods such as vacuum thermal evaporation, spin coating, or printing. The compound used as the organic material layer can be a small organic molecule, a large organic molecule, a polymer, or a combination thereof. The hole transport region is located between the anode and the light-emitting layer. The hole transport region can be a single-layer hole transport layer (HTL), 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 of a hole injection layer (HIL), a hole transport layer (HTL), and an electron blocking layer (EBL).

[0091] According to one embodiment of the present invention, the material of the hole transport layer may be selected from, but is 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 as shown in HT-1 to HT-34 below; or any combination thereof.

[0092]

[0093]

[0094]

[0095]

[0096] However, it is not limited to the above-mentioned materials.

[0097] 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, or one or more compounds from HI-1 to HI-3; 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.

[0098]

[0099] However, it is not limited to the above-mentioned materials.

[0100] According to one embodiment of the present invention, the OLED organic material layer may further include an electron transport region between the light-emitting layer and the cathode.

[0101] According to one embodiment of the present invention, the light-emitting layer may include a light-emitting dye (i.e., a dopant) capable of emitting different wavelength spectra, and may also include a host material. The light-emitting layer may be a monochromatic light-emitting layer emitting 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 pixel patterns, or may be stacked together to form a colored 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-colored light-emitting layer capable of simultaneously emitting different colors such as red and green.

[0102] According to one embodiment of the present invention, the light-emitting layer material can be different materials such as phosphorescent photoluminescent materials and thermally activated delayed fluorescence materials.

[0103] An OLED device can employ a single light-emitting technology or a combination of multiple different light-emitting technologies. These different light-emitting materials, categorized by technology, can emit light of the same color or different colors.

[0104] The compound with the structure shown in Formula I of this invention is applied to the doping material in the light-emitting layer.

[0105] According to one embodiment of the present invention, 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 multilayer structure including at least one of an electron injection layer (EIL), an electron transport layer (ETL), and a hole blocking layer (HBL).

[0106] According to one embodiment of the present invention, 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.

[0107]

[0108]

[0109]

[0110]

[0111]

[0112] However, it is not limited to the above-mentioned materials.

[0113] The device may also 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.

[0114] The beneficial effects of this invention are:

[0115] This invention optimizes the luminescent performance of OLEDs through molecular structure design:

[0116] 1) LA ligand regulation: By adjusting electronic groups and molecular configuration to enhance planarity, reduce intermolecular stacking and nonradiative energy loss, luminescence efficiency and device stability can be improved.

[0117] 2) LB ligand modification: Introducing a nitrogen-containing heterocyclic structure into the pyridine skeleton with a pyridine heterocyclic linker, and utilizing its unique electronic properties to achieve the following advantages: optimizing HOMO / LUMO energy level matching and reducing the charge injection barrier; promoting the effective utilization of triplet excitons; and suppressing exciton quenching and nonradiative transitions.

[0118] 3) Improved overall performance: Compared with traditional materials, OLED devices using this design exhibit lower driving voltage, higher electroluminescence efficiency, and longer lifespan. Attached Figure Description

[0119] Figure 1 The NMR spectrum of the compound with structural formula I-50 is shown. Detailed implementation method:

[0120] The technical solutions of the present invention will be clearly and completely described below in conjunction with the synthetic examples and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0121] Synthesis example 1

[0122] This synthetic example provides an organometallic compound I-50, namely the compound numbered I-50. The specific synthetic steps are as follows:

[0123] (1)L B -50 is not a current technology and needs to be synthesized first. B -50 The steps are as follows:

[0124]

[0125] Under nitrogen protection, 1.0 eq of 4-bromo-2-chloropyridine (CAS: 73583-37-6), 1.0 eq of 4,4-dimethylpiperidine (CAS: 4045-30-1), and 2.0 eq of sodium tert-butoxide were weighed and added to the reaction system. Toluene was added, and under nitrogen protection, 0.04 eq of Pd2(dba)3 and 0.1 eq of PPh3 were added. The mixture was refluxed at 100 °C for 24 h under nitrogen protection, then cooled to 25 °C. After cooling, 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 then subjected to column chromatography (200-300 mesh) with a developing solvent of EA:PE = 1:12 to remove impurities. The receiving liquid was vortexed until no liquid flowed out and dried under vacuum to obtain the intermediate L shown. B I-50 (yield 47%), with an HPLC purity greater than 99.5%.

[0126] Mass spectrometry test value: 224.27.

[0127]

[0128] Under nitrogen protection, weigh out the intermediate L of the compound. B I-50 (1.0 eq), (2-methylbenzofurano[2,3-b]pyridin-8-yl)boronic acid (CAS: 2365531-44-6) (1.5 eq), and anhydrous potassium carbonate (3.0 eq) were added to the reaction system. Toluene, anhydrous ethanol, and purified water were added. Pd(PPh3)4 (0.02 eq) was added under nitrogen protection. The mixture was refluxed at 100°C for 24 h under nitrogen protection, then cooled to 25°C. After cooling, 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 then subjected to column chromatography (200-300 mesh) with a developing solvent of EA:PE = 1:15 to remove impurities. The receiving liquid was vortexed until no liquid flowed out and dried under vacuum to obtain the intermediate L of the compound shown. B -50 (yield 73%), its HPLC purity is greater than 99.5%.

[0129] Mass spectrometry value: 371.36.

[0130] (2) Synthesis of I-50:

[0131]

[0132] Under nitrogen protection, weigh the intermediate of formula L. A -50 (2.3 eq) and IrC13·3H2O (1.0 eq) were added to the reaction system, followed by the addition of a mixed solution of ethylene glycol ethyl ether and purified water. The mixture was refluxed under nitrogen protection for 28 hours, then cooled to room temperature, resulting in the precipitation of precipitate. The precipitate was filtered, washed sequentially with water, anhydrous ethanol, and petroleum ether, and dried to obtain the bridged ligand III-50 shown (yield 62%).

[0133]

[0134] Weigh 1.0 eq of intermediate formula III-50, add 2.5 eq of silver trifluoromethanesulfonate, then add dichloromethane and methanol to the system. Under nitrogen protection, reflux for 26 hours, cool to room temperature, and concentrate the filtrate by column chromatography (short column) until a solid precipitates. The iridium complex intermediate formula II-50 shown is obtained (yield 95%).

[0135]

[0136] Weigh out intermediate formula II-50 (1.0 eq) and add ligand formula L. B-50 (2.5 eq), then anhydrous ethanol was added to the system, and the mixture was refluxed for 48 hours under nitrogen protection. The mixture was then filtered, washed with alcohol, and dried. Dichloromethane was used as a solvent for silica gel column chromatography. The filtrate was concentrated to precipitate the solid, yielding the final compound I-50 (yield 30%).

[0137] The organometallic compound I-50 was subjected to the following analytical tests:

[0138] HPLC purity: greater than 99.5%;

[0139] The mass spectrometry value was 871.44.

[0140] Elemental analysis: Calculated values: C, 63.43; H, 4.63; N, 8.04. Test values: C, 63.45; H, 4.64; N, 8.03.

[0141] The proton NMR spectrum of compound I-50 is attached. Figure 1 .

[0142] Synthesis example 2

[0143] This synthetic example provides an organometallic compound I-788, namely compound numbered I-788, and the specific synthetic steps are as follows:

[0144] (1)L B -778 is not a current technology and needs to be synthesized first. B The steps for -788 are as follows:

[0145] Among them, intermediate L B The synthesis method of I-788 is as described in Synthesis Example 1, and will not be repeated here.

[0146]

[0147] Under nitrogen protection, intermediate L was added sequentially. B I-788 (1.0 eq), deuterated ethanol (50 eq), sodium ethoxide (2.0 eq), N2 displacement three times under N2 protection, heated at 90°C for 36 h. After the reaction was complete, the reaction solution was directly concentrated to dryness under reduced pressure. The crude product was dissolved in DCM, passed through a silica gel funnel, eluted with DCM until no product was obtained, and the filtrate was evaporated to dryness to obtain intermediate L. B -788 (yield rate 92%).

[0148] The mass spectrometry value was 374.41.

[0149] (2) Synthesis of I-788:

[0150]

[0151] Under nitrogen protection, 1.0 eq of 2-bromo-5-(tert-butyl)pyridine (CAS: 1142197-19-0), 1.5 eq of p-tolueneboronic acid (CAS: 5720-05-8)(CAS: 2365531-44-6), and 3.0 eq of anhydrous potassium carbonate were weighed and added to the reaction system. Toluene, anhydrous ethanol, and purified water were added, and 0.02 eq of Pd(PPh3)4 was added under nitrogen protection. After the addition was complete, the mixture was refluxed at 100°C for 24 h under nitrogen protection, then cooled to 25°C. After the reaction 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 then subjected to column chromatography (200-300 mesh) with an eluent of EA:PE = 1:15 to remove impurities. The receiving liquid was vortexed until no liquid flowed out, and then dried under vacuum to obtain the intermediate L shown in the figure. A I-788 (yield 68%), with an HPLC purity greater than 99.5%.

[0152] Mass spectrometry value: 371.36.

[0153]

[0154] Under nitrogen protection, compound intermediate L was added sequentially. A I-788 (1.0 eq), DMSO-d6 (40 eq), NaOH (2.0 eq), N2 displacement three times under N2 protection, heated at 100℃ for 24 h. After the reaction was complete, the product was extracted with ethyl acetate, washed three times with saturated brine, and concentrated under reduced pressure. The crude product was purified by column chromatography, eluting with a PE:EA gradient from 14:1 to 6:1 (v / v) to give intermediate L. A -788 (yield 96%), with an HPLC purity greater than 99.5%.

[0155] The mass spectrometry value was 228.30.

[0156]

[0157] Under nitrogen protection, weigh the intermediate of formula L. A -788 (2.5 eq) and IrC13·3H2O (1.0 eq) were added to the reaction system, along with a mixed solution of ethylene glycol ethyl ether and purified water. The mixture was refluxed under nitrogen protection for 28 hours, then cooled to room temperature, resulting in the precipitation of a precipitate. The precipitate was filtered, washed sequentially with water, anhydrous ethanol, and petroleum ether, and dried to obtain the bridged ligand III-788 shown (yield 66%).

[0158]

[0159] Weigh 1.0 eq of intermediate III-788, add 2.5 eq of silver trifluoromethanesulfonate, then add dichloromethane and methanol to the system. Under nitrogen protection, reflux 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-788 shown is obtained (yield 93%).

[0160]

[0161] Weigh out intermediate formula II-788 (1.0 eq) and add ligand formula L. B -788 (3.0 eq), then anhydrous ethanol was added to the system, and the mixture was refluxed for 36 hours under nitrogen protection. The mixture was then filtered, washed with ethanol, and dried. Dichloromethane was used as a solvent for silica gel column chromatography. The filtrate was concentrated to precipitate the solid, yielding the final compound I-788 (yield 26%).

[0162] The organometallic compound I-788 was subjected to the following analytical tests:

[0163] HPLC purity: greater than 99.5%;

[0164] The mass spectrometry value is 1020.64.

[0165] Elemental analysis: Calculated values: C, 65.92; H, 6.81; N, 6.86. Test values: C, 65.94; H, 6.82; N, 6.85.

[0166] The synthesis methods for other compounds are the same as those described above, and will not be repeated here.

[0167] The present invention also provides an organic electroluminescent device, wherein the organic electroluminescent device is made of the aforementioned organic light-emitting material, more specifically, it is made of an organic light-emitting material of a compound with chemical formula I.

[0168] To further describe the present invention, more specific embodiments are listed below.

[0169] Device Example 1

[0170] Compound I-1 prepared in this invention was selected as the phosphorescent material with a doping concentration of 5% for the fabrication of OLED devices. The specific fabrication method is as follows:

[0171] (1) The glass plate coated with ITO transparent conductive layer was ultrasonically treated in commercial cleaning agent, rinsed in deionized water, ultrasonically degreased in acetone: ethanol mixed solvent (volume ratio 1:1), baked in a clean environment until the moisture was completely removed, cleaned with ultraviolet light and ozone, and bombarded with low-energy cation beam.

[0172] (2) Place the glass substrate with the anode into the vacuum chamber and evacuate to 1×10⁻⁶. -5 ~9×10 -3 Pa, HI-2 is vacuum-deposited on the above-mentioned anolyte film as a hole injection layer at a deposition rate of 0.1 nm / s and a film thickness of 10 nm; then, the first hole layer HT-3 is deposited as a hole transport layer at a deposition rate of 0.1 nm / s and a thickness of 60 nm; then, the electron blocking layer EB-1 is deposited at a deposition rate of 0.1 nm / s and a film thickness of 5 nm.

[0173] (3) An EML is vacuum-deposited on the electron blocking layer as the light-emitting layer of the device. The EML includes the host material GH-1 and the doping material I-1 of the present invention, with a doping mass percentage concentration of 5%, forming the organic light-emitting layer of the device. The deposition rate is 0.2 nm / s and the total deposition film thickness is 30 nm.

[0174] (4) ET-13:QLi with a mass ratio of 1:1 is deposited on the light-emitting layer as the electron transport material of the device electron transport layer. The deposition rate is 0.1 nm / s and the total film thickness is 30 nm.

[0175] (5) A 1 nm thick LiF layer was sequentially vacuum-deposited on the electron transport layer as an electron injection layer, and a 150 nm thick Al layer was deposited as the cathode of the device. After encapsulation, an OLED device was obtained. The performance and luminous characteristics of the obtained device were tested using a KEITHLEY 2400 source measurement unit and a CS-2000 spectroradiometer to evaluate the driving voltage, lifetime, and luminous efficiency.

[0176] Device Comparison Examples 1-4

[0177] Organic electroluminescent devices were prepared using the same method as in Device Example 1, except that the dopant compound I-1 in Device Example 1 was replaced with the structural compounds in Comparative Examples 1-6.

[0178] The structure used is as follows:

[0179]

[0180]

[0181] The prepared organic electroluminescent device was subjected to the same tests as in Example 1, and the results are shown in Table 1.

[0182] Device Examples 2-50

[0183] The method described in Embodiment 1 of the above device is the same, except that the doped material I-1 is replaced with the structure described in the table.

[0184] The driving voltage, luminous efficiency, and lifetime of the organic electroluminescent devices obtained from the above-described device embodiments and comparative examples were characterized at a brightness of 8000 nits. The test results are shown in Table 1 below: (Test results are normalized to Comparative Example 1)

[0185]

[0186]

[0187]

[0188] By comparing comparative compounds 1-4 with the organometallic compounds of the present invention, it can be seen that L B By introducing N-type heterocyclic groups onto dibenzofuranopyridine, the nitrogen-containing heterocyclic compounds of this invention, compared to the comparative compounds, significantly improve the luminous efficiency of OLED devices due to their unique electronic structure and optical properties. Simultaneously, they optimize the HOMO and LUMO energy levels of the molecule, reducing the exciton injection barrier, thereby improving device efficiency and lowering the turn-on voltage. Furthermore, the N-heterocyclic structure can improve luminous performance by regulating the electronic state of the molecule, such as enhancing the formation efficiency of triplet excitons, thus achieving higher luminous efficiency. Moreover, by optimizing the molecular structure and electronic properties, exciton annihilation and non-radiative transitions can be reduced, thereby improving device lifetime. As can be seen from the table above, the organic electroluminescent devices prepared using the compounds of this invention as luminescent layer doping materials exhibit significantly lower driving voltages, significantly improved luminous efficiency, and significantly higher lifetimes compared to the organic electroluminescent devices prepared in the comparative examples.

[0189] A comparison of comparative compounds 1-4 with the organometallic compounds of this invention shows that by adjusting different L... A By altering the structure of the ligands, including some electrons and functional groups, and increasing molecular planarity, molecular stacking and coupling can be reduced, thereby decreasing the non-radiative decay rate and improving luminous efficiency and device stability. As a doping material for the luminescent layer, the organic electroluminescent device prepared by the compound of this invention exhibits significantly lower driving voltage, significantly improved luminous efficiency and lifetime compared to the organic electroluminescent device prepared in the comparative example, and these figures all exceed any value attributable to experimental error.

[0190] A comparison of compound I-405 of the present invention and compound 1 of the comparative example shows that the only difference is that the compound of the present invention has an additional N heterogroup on the dibenzofuran. Because the nitrogen atom of the pyridine ring in its structure has an electron-withdrawing effect, it can lower the LUMO energy level of the material, thereby enhancing the electron injection and transport capabilities. At the same time, it optimizes the hole and electron mobility, reduces the spatial overlap between excitons and charges, reduces triplet annihilation, and can also reduce the electrode quenching effect and increase the radiative transition rate. As a result, compound I-405 of the present invention has improved luminous efficiency and lifetime compared with compound 1 of the comparative example, and also reduced the device start-up voltage.

[0191] The above embodiments only list the effect data of devices made from a portion of the structures. This is a representative sampling test. Based on the experimental data, the overall data is not significantly different and can represent the effects of other unlisted structures.

[0192] Those skilled in the art will readily recognize that many modifications and variations can be made to the invention without departing from its spirit and scope. Therefore, it is contemplated that the invention covers the modifications and variations provided within the scope of the appended claims and their equivalents.

[0193] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An organic electroluminescent material, characterized in that, The general formula for compounds with the structure shown in Formula I is: Ir(L A )2(L B ); Among them, L A and L B Both are ligands, each possessing a bidentate structure of CN: Where m and p are integers between 0 and 3, n is an integer between 0 and 2, and q is an integer between the ring with no substitution and the maximum substitution value; R1, R2, R3, R4, R5, R6, R7, R8, Ar1, Ar2, Ar3, and Ar4 are all independently selected from -H, -D, -T, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, -SiMe3, -GeMe3, substituted or unsubstituted C2-C. 18 Alkyl, substituted or unsubstituted C3-C 18 cycloalkyl, substituted or unsubstituted C6-C 18 Any one of aryl and substituted or unsubstituted 4- to 18-membered heterocyclic groups; Ar1, Ar2, Ar3, and Ar4 may be the same or different; Ring A can be any of the substituted or unsubstituted N-containing 3- to 18-membered heterocyclic groups. If there is only one heteroatom in the heterocycle, it must be N; if there are two or more, one of them is N and the other is one or more of N, O, and S, and the N in the heteroatom is connected to the ring in which it is located. In Formula I, ring A contains a nitrogen atom, and the nitrogen atom is chemically bonded to the pyridine ring; ring A can be an aromatic or non-aromatic structure. Ring B shares two carbon atoms with ring A, and the number of rings B is 0, 1, or 2; When the quantity of ring B is 0 or it does not exist, that is, when ring B is hydrogen; When present, each ring B may be the same or different, and may be any one of C4-C6 cycloalkyl, substituted or unsubstituted C4-C6 aryl, and substituted or unsubstituted 4-6 heterocyclic groups. X is independently selected from one of NR′, O, S, Si R′R″, Ge R′R″, CR′R″ and Se; Wherein, R′ and R″ are independently selected from -H, -D, -T, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, -SiMe3, -GeMe3, substituted or unsubstituted C2-C. 18 Alkyl, substituted or unsubstituted C3-C 18 cycloalkyl, substituted or unsubstituted C6-C 18 Any one of aryl and substituted or unsubstituted 4-18 member heterocyclic groups.

2. The organic electroluminescent material according to claim 1, characterized in that, R1-R8 and Ar1-Ar4 each independently form substituted or unsubstituted C3-C bonds with other substituents on their respective rings. 20 Aliphatic rings, substituted or unsubstituted C6-C 20 Aromatic ring, substituted or unsubstituted C4-C 20 Aromatic heterocyclic, substituted or unsubstituted C 10 -C 20 Fused ring.

3. The organic electroluminescent material according to claim 1, characterized in that, The substituents on the aforementioned substituent groups are selected from at least one or more of -H, -D, -T, -F, -CN, -CH3, -CD3, -CT3, -CF3, -CH2F, -CHF2, -SiMe3, and -GeMe3.

4. The organic electroluminescent material according to claim 1, characterized in that, The heteroatom in the aforementioned heterocyclic group is one or more of N, O, S, Si, and Ge.

5. The organic electroluminescent material according to claim 1, characterized in that, The hydrogen in the aforementioned groups is not replaced by deuterium, or is partially or completely replaced by deuterium.

6. The organic electroluminescent material according to claims 1-2, characterized in that, R1-R8 and Ar1-Ar4 are each independently 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, pyrrolidone, thiacyclopentane, tetrahydropyran, phenyl, biphenyl, deuterated phenyl, bideuterated phenyl, terphenyl, naphthyl, fluorenyl, phenanthryl, anthracene, indene, triphenylene, pyrene, tetraphenyl, perylene, tretinoin, fused tetraphenyl, fluoranyl, furanyl, thiophene, pyrrolyl, imidazole The following groups are included: pyrazolyl, thiazolyl, thiadiazolyl, isothiazolyl, isoxazolyl, oxazolyl, oxadiazolyl, triazinyl, tetraazinyl, triazolyl, tetrazolyl, furazolyl, pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl, benzofuranyl, benzothiopheneyl, isobenzofuranyl, dibenzofuranyl, dibenzothiopheneyl, benzimidazolyl, benzothiazolyl, benzothiazolyl, benzoisothiazolyl, benzoisooxazolyl, benzooxazolyl, isoindolyl, indolyl, inzolyl, benzothiadiazolyl, quinolinyl, isoquinolinyl, cenolinyl, quinazolinyl, quinoxolinyl, carbazole, phenoxazinyl, phenanthidyl, benzo-m-dioxacyclopentenyl, or any combination of the following substituents:

7. The organic electroluminescent material according to claim 1, characterized in that, The ring A is a 5-membered heterocyclic ring or a 6-membered heterocyclic ring.

8. The organic electroluminescent material according to any one of claims 1-7, characterized in that, The organic electroluminescent material is selected from any one of the compounds shown in the following structures:

9. An organic electroluminescent device, characterized in that, The organic electroluminescent device includes a first electrode, a second electrode, and one or more organic layers located between the first electrode and the second electrode; and, The organic layer includes at least one of the following: a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting auxiliary layer, an organic electroluminescent layer, a hole blocking layer, an electron transport layer, and an electron injection layer; and... The organic electroluminescent layer comprises the organic electroluminescent material as described in any one of claims 1 to 8.

10. The organic electroluminescent device according to claim 9, characterized in that, The organic electroluminescent layer comprises a host material and a dopant material, wherein the dopant material contains the organic electroluminescent material.

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