Iridium-containing metal heterocyclic phosphorescent doped material and organic electroluminescent device

Abstract

The invention belongs to the technical field of organic electroluminescent materials, and provides an iridium-containing heterocyclic phosphorescent doping material and an organic electroluminescent device.The doping material has a compound general formula shown in the formula I. Quinoline and a naphthalene ring are connected through silane or germane, and a silicon or germanium six-membered heterocyclic structure is formed. And reacting with iridium metal and a diketone monomer to obtain the iridium metal heterocyclic phosphorescent organic light-emitting material. The heteroatom silicon or germanium in the material can adjust molecular orbital HOMO and LUMO energy levels, and the polarity effect of heteroatoms promotes electron migration, reduces interface potential barriers and electron injection barriers, reduces carrier injection loss and improves carrier mobility, so that driving voltage is reduced, and the external quantum efficiency of a device is improved. In addition, the silicon or germanium heterocyclic ring has better rigidity, so that the overall stability of the structure is enhanced, and the rigid structure can prolong the service life of the device.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic electroluminescent materials, and particularly relates to an iridium-containing metal heterocyclic phosphorescent doped material and an organic electroluminescent device. BACKGROUND

[0002] Organic light-emitting diodes (OLEDs) have been developing vigorously for more than 30 years and have become a new generation of display and lighting technology. In the display field, compared with the traditional liquid crystal display (LCD) technology, OLED display has been widely used in smart phones, televisions, computers, vehicle large screens, VR glasses and other products due to its advantages of high brightness, high contrast, high resolution, ultra-thin display and flexible display. In the lighting field, OLED lighting has brought new changes to the lighting market due to its high color rendering index, planar light source and flexible light source. In OLED devices, organic doped materials play a key role. Doping is to introduce a small amount of impurity atoms or molecules into the host material to change its electronic properties and optical properties. By controlling the type and concentration of doping, the conductivity, light-emitting color and light-emitting efficiency of the material can be adjusted. In the OLED light-emitting layer, the doped material as a guest is mixed with the host material to form a light-emitting layer, which can increase the efficiency of light-emitting molecules, reduce the change of light-emitting color under different electric fields, and also reduce the amount of expensive light-emitting dopant. The mixed film can be formed by vacuum co-evaporation film or by mixing solution and spin coating, spraying or solution printing. At present, doped materials play an indispensable role in improving the performance of OLED devices, and their development is crucial to the progress of OLED technology.

[0003] In the red, green and blue three-color devices of OLEDs, the current efficiency of green OLEDs can meet the practical requirements, and the maximum current efficiency of pure blue OLEDs has also reached a certain level. However, red devices face some challenges. Although the maximum current efficiency of red devices can reach a certain value, it is often obtained at low doping concentration. This is because the red material has a serious concentration quenching problem. With the increase of the doping concentration of the red guest material, the light-emitting efficiency of the device will decrease sharply. Low doping concentration will also lead to complex device manufacturing process and poor reproducibility. However, in recent years, researchers have made continuous explorations, such as constructing a molecular structure with large conjugation, introducing a steric group, etc., which has improved the performance of red materials to some extent, providing the possibility for preparing high-doping-concentration and high-efficiency red OLEDs, but there is still room for further improvement and improvement. SUMMARY

[0004] In order to solve the above problems, the application provides an iridium metal heterocyclic phosphorescent dopant material and an organic electroluminescent device, wherein quinoline and naphthalene rings are connected by silane or germane to form a silicon or germanium six-membered heterocyclic structure, and then reacted with an iridium metal and a diketone monomer to prepare the iridium metal heterocyclic phosphorescent organic luminescent material. The heteroatom in the material can adjust the molecular orbital energy level, reduce the electron injection barrier, and thus improve the external quantum efficiency of the device; the polarity of the heteroatom promotes electron migration and reduces the interface potential barrier, thereby reducing the driving voltage. Meanwhile, the rigid structure of the heterocyclic ring can prolong the service life.

[0005] In order to achieve the above object, the application provides the following technical scheme. An iridium metal heterocyclic phosphorescent dopant material has a compound structure shown in formula I:

[0006] X is selected from Si or Ge; X1, X2 and X3 represent carbon atoms C, and X1 and X2, X2 and X3 can be connected to the following structure: ; Formula I-a and formula I-b cannot appear at the same time; Y1 and Y2 are carbon C; R1, R2, R3 and R4 are the same or different, and each is independently selected from hydrogen, a deuterium atom, halogen, a hydroxyl group, a cyano group, a nitro group, an amino group, a sulfonic acid group, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, an isocyanide group, a mercapto group, a sulfinyl group, a phosphine group, a substituted or unsubstituted C1-C 40 alkyl group, a substituted or unsubstituted C6-C 40 aryl group, a substituted or unsubstituted C4-C 40 heteroaryl group, a substituted or unsubstituted C3-C 40 cycloalkyl group, a substituted or unsubstituted C1-C 40 alkoxy group, a substituted or unsubstituted C2-C 40 alkene group and alkyne group, a substituted or unsubstituted C3-C 40 heterocyclic group, a substituted or unsubstituted C5-C 40 spirocyclic group, a substituted or unsubstituted C1-C 40 silyl group, a substituted or unsubstituted C1-C 40 germane group, and a combination of the above groups; the adjacent substituents at the positions of R2 and R4 can be connected to each other to form a ring.

[0007] The R a ~R c are each independently selected from hydrogen, a deuterium atom, halogen, a cyano group, a substituted or unsubstituted C1-C 20 alkyl group, a substituted or unsubstituted C3-C20 cycloalkyl; R a ~R c The substituents at the positions are the same or different.

[0008] According to one embodiment of the present application, the positions of the substituents R1, R2, R3, and R4 are any positions on the benzene ring; the number of substituents R1 is 0 to 2, the number of substituents R2 is 0 to 3, the number of substituents R3 is 0 to 1, and the number of substituents R4 is 0 to 4.

[0009] According to one embodiment of the present application, the substituents R1 to R4, R a ~R c The hydrogen atoms in the substituents can be replaced by deuterium.

[0010] According to one embodiment of the present application, the adjacent substituents at the positions R2 and R4 can be connected to each other to form a ring, which can be a single ring or a multiple ring (including a spiro ring, a bridged ring, a fused ring, etc.), and an alicyclic ring, a heteroalicyclic ring, an aromatic ring, or a heteroaromatic ring.

[0011] According to one embodiment of the present application, the adjacent substituents are substituents bonded to the same atom, substituents bonded to carbon atoms directly bonded to each other, or substituents bonded to further apart carbon atoms.

[0012] According to one embodiment of the present application, the adjacent substituents are substituents bonded to the same carbon atom and substituents bonded to carbon atoms directly bonded to each other.

[0013] According to one embodiment of the present application, when the substituents at the positions Y1 and Y2 are connected to each other to form a ring, particularly when they are bonded to carbon atoms directly bonded to each other, the connected ring cannot be a naphthalene ring. When one of the adjacent substituents represents hydrogen, the second substituent is bonded to the position of the carbon atom to which the hydrogen atom is bonded to form a ring, the connected ring cannot be a benzothiophene, and the remaining rings can be any.

[0014] According to one embodiment of the present application, each of R1 to R4 is independently selected from an alkyl group having 1 to 10 carbon atoms, including branched and straight chain alkyl groups.

[0015] For example, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, t-butyl, n-pentyl, neopentyl, or n-hexyl.

[0016] According to one embodiment of the present application, each of R1 to R4 is independently selected from an aryl group having 6 to 20 carbon atoms.

[0017] For example, phenyl, biphenyl, naphthyl, fluorenyl.

[0018] According to one embodiment of the present application, R1~ R4 are each independently selected from a heteroaryl group having 4 to 12 carbon atoms, the heteroaryl group comprising a fused ring heteroaryl group, the heteroatom being selected from a combination of one or more of O, S, N, P, B, Si and Ge.

[0019] For example, pyridyl, furanyl, thienyl, pyrimidyl, pyrazyl, imidazyl, oxazyl, thiazyl, pyridazyl, benzofuranyl, benzothienyl, indolyl, quinoline and isoquinoline, carbazyl, dibenzofuranyl, dibenzothienyl, benzimidazyl, benzothiazyl, benzoxolane, benzothiolane.

[0020] According to one embodiment of the present application, R1, R3, R4 are each independently selected from carbazyl, benzofuranyl, benzothienyl, benzoxolane or benzothiolane; and R2 is carbazyl or benzofuranyl.

[0021] According to one embodiment of the present application, R1, R2, R3, R4 are each independently selected from a cycloalkyl group having 3 to 7 carbon atoms.

[0022] For example, cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane.

[0023] According to one embodiment of the present application, R1, R2, R3, R4 are each independently selected from an alkoxy group having 1 to 10 carbon atoms.

[0024] For example, methoxy, ethoxy, propoxy, butoxy, pentoxy, tert-butyloxy.

[0025] According to one embodiment of the present application, R1, R2, R3, R4 are each independently selected from an alkenyl group and an alkynyl group having 2 to 10 carbon atoms.

[0026] For example, ethenyl, propenyl, 1-butenyl, 1-pentenyl, isopropenyl, neopentenyl, trimethylethenyl, ethynyl, propynyl, 1-butynyl, 1-pentynyl, 1-hexynyl, isobutynyl, neopentynyl or tert-butynyl.

[0027] According to one embodiment of the present application, R1~ R4 are each independently selected from a heterocyclic group having 3 to 10 carbon atoms, the heteroatom being selected from a combination of one or more of O, S, N, P, B, Si and Ge, Preferably, the heterocyclic group is selected from an oxiranyl group, an oxetanyl group, an oxolanyl group, an oxanyl group, a dioxolanyl group, a dioxanyl group or a tetrahydrothiophene.

[0028] Most preferably, the heterocyclic group is an oxolanyl group or an oxanyl group.

[0029] According to one embodiment of the present application, each of R1to R4is independently selected from the group consisting of a spiro[5,5]decyl group, a spiro[5,6]undecyl group, a 2,2-dimethylspiro[5,6]undecyl group, and preferably a 2,2-dimethylspiro[5,6]undecyl group.

[0030] According to one embodiment of the present application, each of R1to R4is independently selected from a silane group having 3 to 10 carbon atoms.

[0031] For example, a trimethylsilyl group, a triethylsilyl group, a methyldiethylsilyl group, an ethyldimethylsilyl group, a tripropylsilyl group, a tributylsilyl group, a triisopropylsilyl group, a methyldiisopropylsilyl group, a dimethylisopropylsilyl group, a tri-t-butylsilyl group, a triisobutylsilyl group, a dimethyl-t-butylsilyl group, and a methyl-di-t-butylsilyl group. Of these, the most preferred groups are a trimethylsilyl group and a triethylsilyl group.

[0032] According to one embodiment of the present application, each of R1to R4is independently selected from a germane group having 3 to 10 carbon atoms.

[0033] For example, a trimethylgermyl group, a triethylgermyl group, a methyldiethylgermyl group, an ethyldimethylgermyl group, a tripropylgermyl group, a tributylgermyl group, a triisopropylgermyl group, a methyldiisopropylgermyl group, a dimethylisopropylgermyl group, a tri-t-butylgermyl group, a triisobutylgermyl group, a dimethyl-t-butylgermyl group, and a methyl-di-t-butylgermyl group. Of these, the most preferred groups are a trimethylgermyl group and a triethylgermyl group.

[0034] According to one embodiment of the present application, each of R a ~R c Each of the substituents is independently selected from the group consisting of: .

[0035] wherein indicates the position of attachment of the group.

[0036] The substituents in the "substituted" or "unsubstituted" are substituted with substituents selected from the group consisting of alkyl, cycloalkyl, heteroalkyl, heterocyclyl, aralkyl, alkoxy, aryloxy, alkenyl, alkynyl, aryl, heteroaryl, alkylsilyl, arylsilyl, alkylgermyl, arylgermyl, amino, acyl, carbonyl, carboxylic acid, ester, cyano, sulfinyl, sulfonyl, phosphine, and halogen.

[0037] Preferably, the substituents are deuterium, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, t-butyl, n-pentyl, neopentyl, n-hexyl, phenyl, naphthyl, fluorenyl, biphenyl, terphenyl, cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, ethenyl, ethynyl, oxolane, oxane, tetrahydrofuran, benzofuran, benzothiophene, carbazole, cyano, sulfonic acid, halogen, trimethylsilyl, and trimethylgermyl.

[0038] Further, the specific structure of the iridium metal heterocyclic phosphorescent dopant material is selected from any one of the following, but is not limited to:

[0039]

[0040]

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[0070]

[0071] .

[0072] According to the present application, there is also provided a preparation method of an iridium-containing metal heterocyclic phosphorescent dopant material, the synthesis of which is as follows: .

[0073] The specific synthesis steps are as follows: 1) A three-necked flask is added with toluene, anhydrous ethanol and water, then reactant 1 and reactant 2 are added, nitrogen is replaced, then tetrakis(triphenylphosphine)palladium (Pd(pph3)4 and anhydrous potassium carbonate (K2CO3) are added, nitrogen is replaced, and then the reaction is carried out at 80-100°C for 24-48h. After the reaction is completed, the reaction liquid is separated by liquid separation, rotary evaporation and column chromatography to obtain intermediate 1.

[0074] 2) A three-necked flask is added with tetrahydrofuran solvent and intermediate 1, nitrogen is replaced twice, then the temperature is reduced to -78°C. Then under the nitrogen atmosphere, n-butyllithium is added dropwise, and after the dropwise addition is completed, the reaction is stirred at -78°C for 1h. Then reactant 3 is slowly added dropwise into the three-necked flask, and the temperature is slowly increased to room temperature for reaction for 3h. After the reaction is completed, the reaction liquid is poured into ice water for quenching, then separated by liquid separation with ethyl acetate, rotary evaporation and recrystallization to obtain intermediate 2.

[0075] 3) In a three-necked flask, add ethylene glycol ether and water, put intermediate 2 into the reaction system, replace nitrogen, then add iridium trichloride, and reflux at 120℃ under nitrogen protection. After the reaction is completed, cool to room temperature. Then filter, rinse with anhydrous ethanol and petroleum ether, and dry to obtain intermediate 3.

[0076] 4) In a three-necked flask, add ethylene glycol ether and water, put intermediate 3 into the reaction system, replace nitrogen, then add formula II, and reflux at 120℃ under nitrogen protection. After the reaction is completed, cool to room temperature. Then filter the precipitate, rinse with anhydrous ethanol, and dry to obtain a compound with the structure shown in formula I.

[0077] According to the present application, an organic electroluminescent device is also provided, which comprises an anode, a cathode and an organic functional layer arranged between the anode and the cathode, the organic functional layer comprising a hole transport layer, a light-emitting layer and an electron transport layer; the light-emitting layer comprising a host material and a dopant material, the dopant material comprising the organic metal iridium complex luminescent material as described above.

[0078] The material of the anode can be divided into two categories, the first category being traditional anode materials such as indium tin oxide (ITO), indium zinc oxide (IZO), gold (Au), silver (Ag) and the like, and the second category being new anode materials such as poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS), polyaniline (PANI), graphene composite electrode and the like.

[0079] In an embodiment of the present application, the material of the hole transport layer can be a phthalocyanine derivative, a conductive polymer or a polymer containing a conductive dopant, such as polyphenylenevinylene, polyaniline / dodecylbenzenesulfonic acid, poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonate), polyaniline / camphor sulfonic acid, polyaniline / poly(4-styrenesulfonate), an aromatic amine derivative and the like.

[0080] In an embodiment of the present application, the hole transport layer can also be used as a hole injection layer and an electron blocking layer. The hole injection layer is located between the anode and the hole transport layer, and the material used for the hole injection layer can be improved PEDOT:PSS, formula A and formula B, but is not limited to the above-mentioned materials.

[0081] .

[0082] In an embodiment of the present application, the light-emitting layer comprises a host material and a dopant material, the host material providing a carrier transport channel, and the dopant material improving the light-emitting efficiency, and generally being a red, green or blue phosphor material, such as the iridium metal phosphor material with the structure shown in formula I in the present application as the dopant material.

[0083] In one embodiment of the present application, the electron transport layer is a single layer structure, and the material of the electron transport layer can be a single compound or a combination of multiple compounds, such as Alq3 (tris(8-hydroxyquinoline) aluminum), Znq (tris(8-hydroxyquinoline) zinc), Bebq2 (bis(10-hydroxybenzo[h]quinoline) beryllium, TPBi (1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl) benzene), Bphen (4,7-diphenyl-1,10-phenanthroline), TAZ (1,2,4-triazole derivative), or polyfluorene derivative and poly-p-phenylenevinylene.

[0084] In one embodiment of the present application, the electron transport layer can also be used as an electron injection layer and a hole blocking layer.

[0085] In one embodiment of the present application, the electron injection layer is located between the electron transport layer and the cathode, and the material of the electron injection layer can be one or more of LiF, NaCl, CsF, Li2O, Cs2CO3, BaO, Na, Li, and Ca.

[0086] In one embodiment of the present application, the cathode material includes magnesium (Mg), silver (Ag), aluminum (Al), aluminum lithium (Al Li), calcium (Ca), magnesium indium (Mg In), magnesium silver (Mg Ag), and the like, or an alloy thereof, and any combination thereof.

[0087] Compared with the prior art, the present application has the following beneficial effects: The present application provides an iridium metal heterocyclic phosphorescent dopant material, which is prepared by connecting quinoline and naphthalene ring through silicon or germanium atoms to form a silicon or germanium six-membered heterocyclic structure, and then reacting with iridium metal and diketone monomer. The introduction of the silicon or germanium six-membered heterocyclic structure in the material can adjust the molecular orbital HOMO and LUMO energy level, the polarity of silicon or germanium promotes electron migration, reduces interface potential barrier, reduces electron injection barrier, reduces carrier injection loss, and improves carrier mobility, thereby reducing the driving voltage and improving the external quantum efficiency of the device. At the same time, the silicon or germanium heterocyclic structure has good rigidity and stability, so that the service life of the device can be prolonged. Therefore, the iridium metal heterocyclic phosphorescent dopant material provided by the present application has good luminous efficiency, low driving voltage, and long service life. BRIEF DESCRIPTION OF DRAWINGS

[0088] Figure 1 The nuclear magnetic resonance hydrogen spectrum of the iridium metal heterocyclic phosphorescent dopant material of structural formula I-9 prepared in Example 1. DETAILED DESCRIPTION

[0089] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work are within the protection scope of the present application.

[0090] In addition, it should be noted that the numerical values given in the following embodiments are as accurate as possible, but those skilled in the art understand that due to the inevitable measurement errors and experimental operation problems, each number should be understood as an approximate number, rather than an absolutely accurate number.

[0091] Embodiment 1 Synthesis of iridium metal heterocyclic phosphorescent dopant material I-9, i.e., compound numbered I-9, is as follows: 1. Synthesis of reactant 1-1

[0092] In a three-necked flask, raw material 1 (1 eq) and 25 times the mass of raw material 1 of dichloromethane were added, and nitrogen was replaced twice. Then azobisisobutyronitrile (0.1 eq) was added, and nitrogen was replaced once. The temperature was reduced to 0°C, N-bromosuccinimide (1.1 eq) was slowly added dropwise at this temperature, and then the temperature was increased to 40°C, and the reaction was refluxed for 6 h. After the reaction was completed, it was quenched by sodium sulfite aqueous solution, separated, rotary evaporated, and column chromatographed to obtain reactant 1-1.

[0093] 2. Synthesis of reactant 2-1

[0094] In a three-necked flask, 25 times the mass of 7-tert-butyl-naphthalene-2-boronic acid of N,N-dimethylformamide was added, and after nitrogen was replaced twice, 7-tert-butyl-naphthalene-2-boronic acid (1 eq), N-bromosuccinimide (1.2 eq) and azobisisobutyronitrile (8% eq) were added, and after nitrogen was replaced twice, the reaction was carried out at 25°C or below for 24 h in the dark; after the reaction was completed, pure water was added for quenching, separated by ethyl acetate, then rotary evaporated, column chromatographed and purified to obtain reactant 2-1.

[0095] 3. Synthesis of intermediate 1-1

[0096] In a three-necked flask, 20 times the mass of reactant 1-1 of toluene, 10 times of anhydrous ethanol and water were added, then reactant 1-1 (1 eq) and reactant 2-1 (2 eq) were added, after two times of nitrogen replacement, Pd (pph3) 4 (0.2% eq) and anhydrous potassium carbonate (K2CO3) (3 eq) were added, then two times of nitrogen replacement was carried out, and the reaction was carried out at 100°C for 24h. After the reaction was completed, the reaction liquid was separated by liquid-liquid extraction, rotary evaporation, and column chromatography to obtain intermediate 1-1.

[0097] 4, Synthesis of intermediate 2-1

[0098] In a three-necked flask, 20 times the mass of intermediate 1-1 of tetrahydrofuran solvent, and intermediate 1-1 (1 eq) were added, after two times of nitrogen replacement, the temperature was reduced to -78°C. Then under the protection of nitrogen, n-butyllithium (3 eq) was added dropwise, and after the dropwise addition was completed, it was stirred at -78°C for 1h. Then dimethyldichlorosilane (3 eq) (CAS: 75-78-5) was slowly added to the three-necked flask, and slowly warmed to room temperature for 3h. After the reaction was completed, the reaction liquid was poured into ice water for quenching, then separated by liquid-liquid extraction with ethyl acetate, rotary evaporation, and recrystallization to obtain intermediate 2-1.

[0099] 5, Synthesis of formula I-9 .

[0100] In a three-necked flask, 15 times the mass of intermediate 2-1 of ethylene glycol ethyl ether and 3 times of water were added, then intermediate 2-1 was added, after two times of nitrogen replacement, iridium trichloride was added, then under the protection of nitrogen, the reaction was carried out at 120°C for 48h. After the reaction was completed, it was cooled to room temperature. Then by suction filtration, using anhydrous ethanol, petroleum ether was used for washing in turn, and finally dried to obtain intermediate 3-1.

[0101] In a three-necked flask, 10 times the mass of intermediate 3-1 of ethylene glycol ethyl ether was added, then intermediate 3-1 was added, after two times of nitrogen replacement, formula II-1 was added. Then under the protection of nitrogen, the reaction was carried out at 120°C for 48h. After the reaction was completed, it was cooled to room temperature, the precipitate was suction filtered, washed with anhydrous ethanol and dried to obtain a compound with the structure shown in formula I-9.

[0102] Mass test value: 1164.93. Nuclear magnetic resonance data is shown in Figure 1 .

[0103] The synthesis methods of other compounds are the same as above, which will not be described one by one.

[0104] Device preparation example 1 The compound with the structure shown in formula I-9 prepared in example 1 was applied to an organic electroluminescent device as a dopant of the light-emitting layer, and the preparation method was as follows: 1. Cut the ITO patterned glass substrate on the anode into a size of 50 mm x 50 mm x 0.5 mm, clean it with detergent for three times, 5 minutes each time, then sequentially treat it with isopropanol, acetone for 10 minutes by ultrasonic, dry it with nitrogen, and finally expose it to ultraviolet light and ozone for 30 minutes.

[0105] 2. Load the obtained glass substrate onto a vacuum deposition device, first evaporate formula A on the anode as a hole injection layer, with a thickness of 100 angstroms. Then evaporate the first hole layer formula C, with a thickness of 600 angstroms; then evaporate the electron blocking layer formula D, with a film thickness of 50 nm; the structural formulas of formula A, formula C, and formula E are as follows:

[0106]

[0107] 3. Prepare the host material 4,4'-bis(N-carbazolyl) 1,1'-biphenyl (CBP) and the compound represented by formula I-9 prepared in Example 1 as a dopant material according to a mass ratio of 95:5 to form a light-emitting layer, with a thickness of 400 angstroms. Then evaporate a TPBI (formula E) electron transport layer with a thickness of 400 angstroms on the light-emitting layer, evaporate a LiF electron injection layer with a thickness of 10 angstroms on the electron transport layer, and finally evaporate a cathode material Al with a thickness of 1500 angstroms on the electron injection layer, thereby obtaining an organic electroluminescent device.

[0108] Referring to Device Preparation Example 1, replace the compound represented by formula I-9 with compounds formula I-1, I-5, I-43, I-57, I-79, I-101, I-134, I-141, I-152, I-178, I-197, I-218, I-235, I-250, I-263, I-283, I-298, I-452, and I-538, and apply them as dopant materials of the light-emitting layer to the organic electroluminescent device, respectively, which are recorded as Device Preparation Examples 2-20, as shown in Table 1.

[0109] Device Comparative Examples 1-10 Prepare an organic electroluminescent device by the same method as Device Preparation Example 1, except that the dopant material formula I-9 in the light-emitting layer is replaced with compounds 1-10, to obtain Device Comparative Examples 1-10.

[0110] The structures of compounds 1-10 are shown as follows: .

[0111] To further illustrate the luminescent performance of the iridium metal heterocyclic phosphorescent material prepared by the present application, the luminescent characteristics of the organic light-emitting device prepared in Device Preparation Examples 1-20 and the device obtained in Device Comparative Examples 1-10 were tested, and the measurement was performed by using a KEITHLEY 2400-type source measurement unit and a CS-2000 spectroradiometric luminance meter to evaluate the driving voltage, the luminescent efficiency and the service life. The results were normalized with the results of Device Comparative Example 1 as the benchmark, and the results are shown in Table 1.

[0112] Table 1. Luminescent detection data of the organic electroluminescent device

[0113]

[0114] As can be seen from Table 1, when the luminescent brightness is 3000, the luminescent efficiency and the service life of the device prepared in Device Preparation Examples 1-20 are longer, and the driving voltage is lower compared with the devices prepared in Device Comparative Examples 1-6. This is because the six-membered heterocycle containing silicon or germanium in the structure causes the efficiency and the service life to increase and the driving voltage to decrease.

[0115] Specifically, first, the empty 3d and 4d orbitals of the silicon / germanium atom in the silicon / germanium six-membered heterocycle can adjust the molecular orbital energy level, reduce the electron injection barrier, reduce the carrier injection loss, improve the exciton recombination probability, and improve the external quantum efficiency. Second, the polar effect of the silicon / germanium atom can promote the migration of electrons and reduce the interface potential barrier between the electron transport layer and the luminescent layer. Finally, the rigid structure of the six-membered silicon / germanium heterocycle can improve the glass transition temperature, slow down the molecular aggregation or crystallization at high temperature, reduce the non-radiative decay, and the atomic radius of the germanium atom is larger, and the steric hindrance effect is stronger, further inhibiting the molecular motion.

[0116] In addition, when the luminescent brightness is 3000, the efficiency and the service life of the device prepared in Device Preparation Examples 1-20 are longer, and the driving voltage is lower compared with the devices prepared in Device Comparative Examples 7-10. The reason is that the electron-withdrawing property of the sulfur atom exacerbates the uneven distribution of the electron cloud in the molecule, destroys the balance of electron-hole transport, and leads to a decrease in exciton recombination efficiency, thereby reducing the efficiency. The multiple benzene rings are fused, promoting the intermolecular π-π stacking, causing the diffusion and annihilation of excitons, and accelerating the aging of the luminescent layer; the sulfur atom is easily oxidized at high temperature, leading to material degradation, and thus the service life is reduced. In addition, the fused benzene rings will raise the HOMO energy level, and the benzothiophene will lower the LUMO energy level, resulting in a misadjustment of the transport layer energy level, thereby requiring a higher voltage to maintain the current.

[0117] In summary, the organic electroluminescent device prepared by using the compound provided by the present application as the doping material of the luminescent layer has a relatively low driving voltage, a better luminescent efficiency, and a longer service life.

[0118] The above merely provides the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, according to the technical solution and concept of the present application, can make equivalent replacements or changes within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. An iridium-containing metal heterocyclic phosphorescent doping material, characterized in that: The compound having the structure shown in Formula I has the general formula: wherein X is selected from Si or Ge; X1, X2 and X3 represent carbon atoms, and X1 and X2, X2 and X3 are linked to the following structure: ； Wherein, Formula Ia and Formula Ib cannot appear at the same time; Y1 and Y2 are carbon C; R1, R2, R3, R4 substituents are the same or different and are independently selected from hydrogen, deuterium atoms, halogen, hydroxyl, cyano, nitro, amino, sulfonic acid, acyl, carbonyl, carboxylic acid, ester, isocyano, mercapto, sulfinyl, phosphino, substituted or unsubstituted C1-C 40 Alkyl, substituted or unsubstituted C6-C 40 Aryl, substituted or unsubstituted C4-C 40 Heteroaryl, substituted or unsubstituted C3-C 40 Cycloalkyl, substituted or unsubstituted C1-C 40 Alkoxy, substituted or unsubstituted C2-C 40 Alkenyl and alkyne groups, substituted or unsubstituted C3-C 40 Heterocyclyl, substituted or unsubstituted C5-C 40 Spirocyclyl, substituted or unsubstituted C1-C 40 Silane, substituted or unsubstituted C1-C 40 Germyl, and combinations thereof; wherein two adjacent substituents at the R2 and R4 positions can be connected to each other to form a ring; The R a ~R c are each independently selected from hydrogen, a deuterium atom, a halogen, a cyano group, a substituted or unsubstituted C1-C 20 Alkyl, substituted or unsubstituted C3-C 20 Cycloalkyl, R a ~R c The substituents at the respective positions may be the same or different.

2. The iridium-containing metal heterocyclic phosphorescent doping material according to claim 1, characterized in that: The positions of the R1, R2, R3, and R4 substituents are any positions on the benzene ring; The number of the R1 substituents is 0-2, the number of the R2 substituents is 0-3, the number of the R3 substituents is 0-1, and the number of the R4 substituents is 0-4.

3. The iridium-containing metal heterocyclic phosphorescent doping material according to claim 1, characterized in that: R1~R4, R a ~R c The hydrogen atoms in the substituent groups can be deuterated; The ring formed by connecting adjacent substituents at the R2 and R4 positions is a monocyclic ring, a polycyclic ring, an alicyclic ring, a heteroalicyclic ring, an aromatic ring or a heteroaromatic ring.

4. The iridium-containing metal heterocyclic phosphorescent doping material according to claim 1, characterized in that: When the substituents at the Y1 and Y2 positions are linked to each other to form a ring, the linked ring cannot be a naphthalene ring when they are bonded to the carbon atoms directly bonded to each other; When one of two adjacent substituents represents hydrogen, and the second substituent is bonded to the carbon atom to which the hydrogen atom is bonded to form a ring, the ring formed by the connection cannot be benzothiophene.

5. The iridium-containing metal heterocyclic phosphorescent doping material according to claim 1, wherein: The R1 to R4 are each independently selected from an alkyl group having 1 to 10 carbon atoms; or the R1 to R4 are each independently selected from an aryl group having 6 to 20 carbon atoms.

6. The iridium-containing metal heterocyclic phosphorescent doping material according to claim 1, characterized in that: R1 to R4 are each independently selected from a heteroaryl group having 4 to 12 carbon atoms, wherein the heteroaryl group includes a fused ring heteroaryl group, and the heteroatom is selected from one or more combinations of O, S, N, P, B, Si and Ge; Alternatively, R1, R3, and R4 are each independently selected from carbazolyl, benzofuranyl, benzothiophenyl, benzoxolane, or benzothiolane; and R2 is carbazolyl or benzofuranyl.

7. The iridium-containing metal heterocyclic phosphorescent doping material according to claim 1, characterized in that: R1, R2, R3, and R4 are each independently selected from a cycloalkyl group having 3 to 7 carbon atoms; Alternatively, R1, R2, R3, and R4 are each independently selected from an alkoxy group having 1 to 10 carbon atoms; Alternatively, R1, R2, R3, and R4 are each independently selected from an alkene group and an alkyne group having 2 to 10 carbon atoms; Alternatively, R1 to R4 are each independently selected from a heterocyclic group having 3 to 10 carbon atoms, and the heteroatom is selected from a combination of one or more of O, S, N, P, B, Si and Ge; Alternatively, each of R1 to R4 is independently selected from spiro[5,5]decyl, spiro[5,6]undecyl or 2,2-dimethylspiro[5,6]undecyl; Alternatively, R1 to R4 are each independently selected from a silyl group having 3 to 10 carbon atoms; Alternatively, R1 to R4 are each independently selected from a germanium group having 3 to 10 carbon atoms.

8. The iridium-containing metal heterocyclic phosphorescent doping material according to claim 1, characterized in that: The R a ~R c The substituents are each independently selected from the following groups: in Indicates the attachment position of the group.

9. The iridium-containing metal heterocyclic phosphorescent doping material according to claim 1, characterized in that: The iridium metal heterocyclic phosphorescent doping material is selected from any one of the following: 。 10. An organic electroluminescent device, characterized in that: The organic electroluminescent device includes an anode, a cathode, and an organic functional layer arranged between the anode and the cathode, wherein the organic functional layer includes a hole transport layer, a light-emitting layer, and an electron transport layer; the light-emitting layer includes a host material and a doping material, and the doping material is the iridium-containing metal heterocyclic phosphorescent doping material according to any one of claims 1 to 9.

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