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

Abstract

The application belongs to the technical field of organic electroluminescent materials, and provides an iridium metal heterocyclic phosphorescent doped material and an organic electroluminescent device, wherein the doped material has a compound general formula with a structure shown in formula I, a quinoline and a naphthalene ring are connected through silane or germane to form a silicon or germanium six-membered heterocyclic structure, then reacted with an iridium metal and a diketone monomer to obtain an iridium metal heterocyclic phosphorescent organic luminescent material. The heteroatom silicon or germanium in the material can adjust the molecular orbital HOMO and LUMO energy levels, meanwhile, the polarity of the heteroatom promotes electron migration, reduces the interface potential barrier and the electron injection barrier, reduces the carrier injection loss, and improves the carrier mobility, thereby reducing the driving voltage and improving the external quantum efficiency of the device. In addition, the silicon or germanium heterocycle has good 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.

[0006] An iridium metal heterocyclic phosphorescent dopant material has a compound structure shown in formula I:

[0007]

[0008] X is selected from Si or Ge;

[0009] X1, X2 and X3 represent carbon atoms C, and X1 and X2, X2 and X3 can be connected to the following structure:

[0010]

[0011] Formula I-a and formula I-b cannot appear at the same time.

[0012] Y1 and Y2 are carbon C;

[0013] R1, R2, R3 and R4 are the same or different, and each is independently selected from hydrogen, a deuterium atom, a 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 silane 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. ​

[0014] R1, R2, R3, R4 a R1, R2, R3, R4 c each independently selected from hydrogen, deuterium atom, halogen, cyano, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C3-C10 cycloalkyl; R1, R2, R3, R4 20 alkyl, substituted or unsubstituted C3-C10 cycloalkyl; R1, R2, R3, R4 20 alkyl, substituted or unsubstituted C3-C10 cycloalkyl; R1, R2, R3, R4 a R1, R2, R3, R4 c The substituents at the positions of R1, R2, R3, R4 are the same or different.

[0015] According to an embodiment of the present application, the positions of R1, R2, R3, R4 are any positions of the benzene ring; the number of R1 substituents is 0-2, the number of R2 substituents is 0-3, the number of R3 substituents is 0-1, and the number of R4 substituents is 0-4.

[0016] According to an embodiment of the present application, the substituents of R1-R4, R a R1, R2, R3, R4 c may be replaced by deuterium atom.

[0017] According to an embodiment of the present application, the adjacent substituents at the positions of R2 and R4 can be connected to each other to form a ring, which can be monocyclic or polycyclic (including spiro ring, bridged ring, fused ring, etc.), and aliphatic ring, heteroaliphatic ring, aromatic ring or heteroaromatic ring.

[0018] According to an embodiment of the present application, the adjacent substituents refer to the substituents bonded to the same atom, the substituents bonded to the carbon atoms directly bonded to each other, or the substituents bonded to the carbon atoms further away.

[0019] According to an embodiment of the present application, the adjacent substituents refer to the substituents bonded to the same carbon atom and the substituents bonded to the carbon atoms directly bonded to each other.

[0020] According to an embodiment of the present application, when the substituents at the positions of Y1 and Y2 are connected to form a ring, especially when they are bonded to the carbon atoms directly bonded to each other, the connected ring cannot be naphthalene ring.

[0021] When one of the adjacent two 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 benzothiophene, and the rest of the rings are all possible.

[0022] According to an embodiment of the present application, R1-R4 are each independently selected from alkyl with carbon atom number of 1-10; including branched and straight chain alkyl.

[0023] For example, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, t-butyl, n-pentyl, neopentyl or n-hexyl.

[0024] According to one embodiment of the present application, R1to R4are each independently selected from an aryl group having 6 to 20 carbon atoms.

[0025] For example, phenyl, biphenyl, naphthyl, fluorenyl.

[0026] According to one embodiment of the present application, R1to R4are each independently selected from a heteroaryl group having 4 to 12 carbon atoms, the heteroaryl group including 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.

[0027] For example, pyridyl, furanyl, thienyl, pyrimidyl, pyrazyl, imidazyl, oxazyl, thiazyl, pyridazyl, benzofuranyl, benzothienyl, indolyl, quinoline and isoquinoline, carbazyl, dibenzofuranyl, dibenzothienyl, benzimidazyl, benzothiazyl, benzoxazolyl, benzothiazolyl.

[0028] According to one embodiment of the present application, R1, R3, R4are each independently selected from carbazyl, benzofuranyl, benzothienyl, benzoxazolyl or benzothiazolyl; and R2is carbazyl or benzofuranyl.

[0029] According to one embodiment of the present application, R1, R2, R3, R4are each independently selected from a cycloalkyl group having 3 to 7 carbon atoms.

[0030] For example, cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane.

[0031] According to one embodiment of the present application, R1, R2, R3, R4are each independently selected from an alkoxy group having 1 to 10 carbon atoms.

[0032] For example, methoxy, ethoxy, propoxy, butoxy, pentoxy, t-butyloxy.

[0033] According to one embodiment of the present application, R1, R2, R3, R4are each independently selected from an alkenyl group and an alkynyl group having 2 to 10 carbon atoms.

[0034] For example, ethenyl, propenyl, 1-butenyl, 1-pentenyl, isopropenyl, neopentenyl, trimethylethenyl, ethynyl, propynyl, 1-butynyl, 1-pentynyl, 1-hexynyl, isobutynyl, neopentynyl or t-butynyl.

[0035] According to one embodiment of the present application, R1to R4are 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.

[0036] Preferably, the heterocyclyl group is selected from oxiranyl, oxetanyl, oxolanyl, oxepanyl, dioxolanyl, dioxanyl or tetrahydrothiophene.

[0037] Most preferably, the heterocyclyl group is oxolanyl or oxepanyl.

[0038] According to one embodiment of the present application, each of R1~ R4is independently selected from a group consisting of a silaalkyl group having 3 to 10 carbon atoms.

[0039] According to one embodiment of the present application, each of R1~ R4is independently selected from a group consisting of a silaalkyl group having 3 to 10 carbon atoms.

[0040] For example, trimethylsilyl, triethylsilyl, methyldiethylsilyl, ethyldimethylsilyl, tripropylsilyl, tributylsilyl, triisopropylsilyl, methyldiisopropylsilyl, dimethylisopropylsilyl, tri-t-butylsilyl, triisobutylsilyl, dimethyl-t-butylsilyl, methyldi-t-butylsilyl. Among them, the most preferable groups are trimethylsilyl and triethylsilyl.

[0041] According to one embodiment of the present application, each of R1~ R4is independently selected from a group consisting of a germanium alkyl group having 3 to 10 carbon atoms.

[0042] For example, trimethylgermyl, triethylgermyl, methyldiethylgermyl, ethyldimethylgermyl, tripropylgermyl, tributylgermyl, triisopropylgermyl, methyldiisopropylgermyl, dimethylisopropylgermyl, tri-t-butylgermyl, triisobutylgermyl, dimethyl-t-butylgermyl, methyldi-t-butylgermyl. Among them, the most preferable groups are trimethylgermyl and triethylgermyl.

[0043] According to one embodiment of the present application, each of R a ~R c Each of the substituents is independently selected from the following groups:

[0044] .

[0045] wherein indicates the position of attachment of the group.

[0046] The "substituted" or "unsubstituted" means that the substituents can be alkyl, cycloalkyl, heteroalkyl, heterocyclyl, aralkyl, alkoxy, aryloxy, alkenyl, alkynyl, aryl, heteroaryl, alkylsilyl, arylsilyl, alkylgermyl, arylgermyl, amino, acyl, carbonyl, carboxylic acid, ester, cyano, sulfinyl, sulfonyl and phosphine as well as halogen.

[0047] 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.

[0048] 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:

[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] .

[0083] 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:

[0084] .

[0085] The specific synthesis steps are as follows:

[0086] 1) Add toluene, anhydrous ethanol and water into a three-necked flask, then add reactant 1 and reactant 2, replace nitrogen, then add tetra (triphenylphosphine) palladium (Pd (pph3) 4 and anhydrous potassium carbonate (K2CO3) into the flask, replace nitrogen, react at 80-100°C for 24-48h, after the reaction is completed, separate the liquid, spin evaporate, and perform column chromatography to obtain intermediate 1.

[0087] 2) In a three-necked flask, THF solvent and intermediate 1 were added, and after two times of nitrogen replacement, the temperature was reduced to -78℃. Then under the protection of nitrogen, n-butyllithium was added dropwise, and after the completion of dropwise addition, it was stirred at -78℃ for 1h. Then the reactant 3 was slowly added dropwise into the three-necked flask, and slowly warmed to room temperature for 3h. After the completion of the reaction, the reaction liquid was poured into ice water for quenching, and then separated by ethyl acetate, and dried by spinning, and recrystallized to obtain intermediate 2.

[0088] 3) In a three-necked flask, ethylene glycol ether and water were added, and intermediate 2 was added into the reaction system, and then nitrogen was replaced, and then iridium trichloride was added, and the reaction was carried out under the protection of nitrogen at 120℃. After the completion of the reaction, it was cooled to room temperature. Then it was filtered, and then washed with anhydrous ethanol and petroleum ether in sequence, and dried to obtain intermediate 3.

[0089] 4) In a three-necked flask, ethylene glycol ether was added, and intermediate 3 was added into the reaction system, and then nitrogen was replaced, and then formula II was added, and the reaction was carried out under the protection of nitrogen at 120℃. After the completion of the reaction, it was cooled to room temperature. Then the precipitate was filtered, and then washed with anhydrous ethanol and dried to obtain a compound with the structure shown in formula I.

[0090] 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.

[0091] The material of the anode can be divided into two categories, the first category being a traditional anode material, such as indium tin oxide (ITO), indium zinc oxide (IZO), gold (Au), silver (Ag) and the like, and the second category being a new anode material, such as poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS), polyaniline (PANI), graphene composite electrode and the like.

[0092] 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.

[0093] 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.

[0094] .

[0095] In one embodiment of the present application, the light-emitting layer comprises a host material and a dopant material, the host material provides a carrier transport channel, and the dopant material improves the light-emitting efficiency, and is generally a red, green or blue phosphor material, such as the iridium metal phosphor material of structure I in the present application.

[0096] 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-benzimidazole-2-yl) benzene), Bphen (4, 7-diphenyl-1, 10-phenanthroline), TAZ (1, 2, 4-triazole derivative) or polyfluorene derivative and poly-p-phenylenevinylene.

[0097] 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.

[0098] 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, Ca.

[0099] In one embodiment of the present application, the cathode material comprises magnesium (Mg), silver (Ag), aluminum (Al), aluminum lithium (Al Li), calcium (Ca), magnesium indium (Mg In), magnesium silver (Mg Ag) metal or alloy and any combination thereof.

[0100] Compared with the prior art, the present application has the following beneficial effects:

[0101] The application provides an iridium metal heterocyclic phosphorescent dopant material, which is prepared by connecting quinoline and naphthalene rings through silicon or germanium atoms to form a silicon or germanium six-membered heterocyclic structure, and then reacting with an iridium metal and a diketone monomer. The introduction of the silicon or germanium six-membered heterocyclic structure in the material can adjust the HOMO and LUMO energy levels of the molecule, the polarity of the silicon or germanium promotes electron migration, reduces the interface potential barrier, reduces the electron injection barrier, reduces the carrier injection loss, and improves the 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 application has good luminous efficiency, low driving voltage and long service life. BRIEF DESCRIPTION OF DRAWINGS

[0102] 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

[0103] The technical solutions in the examples of the application will be described clearly and completely below. Obviously, the described examples are only a part of the examples of the application, rather than all the examples. Based on the examples in the application, all other examples obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0104] In addition, it should be noted that the numerical values given in the following examples are as accurate as possible, but those skilled in the art understand that, due to unavoidable measurement errors and experimental operation problems, each number should be understood as an approximate number, rather than an absolutely accurate number.

[0105] Example 1

[0106] The iridium metal heterocyclic phosphorescent dopant material I-9, i.e., the compound numbered I-9, is synthesized according to the following specific synthesis steps:

[0107] 1. Synthesis of reactant 1-1

[0108]

[0109] A three-necked flask is added with raw material 1 (1 eq) and dichloromethane with a mass of 25 times that of the raw material 1, and replaced with nitrogen twice. Then azobisisobutyronitrile (0.1 eq) is added, and replaced with nitrogen once. The temperature is reduced to 0℃, N-bromosuccinimide (1.1 eq) is slowly added dropwise at the temperature, and then the temperature is increased to 40℃, and the reaction is refluxed for 6 h. After the reaction is completed, the reaction is quenched by sodium sulfite aqueous solution, separated, rotary evaporated, and column chromatographed to obtain the reactant 1-1.

[0110] 2. Synthesis of reactant 2-1

[0111]

[0112] In a three-necked flask, 25 times 7-tert-butyl-naphthalene-2-boronic acid mass of N, N-dimethylformamide was added, and after replacing nitrogen twice, 7-tert-butyl-naphthalene-2-boronic acid (1 eq), N-bromosuccinimide (1.2 eq) and azobisisobutyronitrile (8% eq) were added, and after replacing nitrogen twice, the reaction was carried out for 24 h at 25°C in the dark; after the reaction was completed, pure water was added for quenching, and ethyl acetate was used for liquid separation, and then rotary evaporation, column chromatography and purification were carried out to obtain the reactant 2-1.

[0113] 3. Synthesis of intermediate 1-1

[0114]

[0115] In a three-necked flask, 20 times reactant 1-1 mass of toluene, 10 times anhydrous ethanol and water were added, and then reactant 1-1 (1 eq) and reactant 2-1 (2 eq) were added, and after replacing nitrogen twice, Pd (pph3) 4 (0.2% eq) and anhydrous potassium carbonate (K2CO3) (3 eq) were added, and then nitrogen was replaced twice, and the reaction was carried out for 24 h at 100°C, and after the reaction was completed, liquid separation, rotary evaporation and column chromatography were carried out to obtain the intermediate 1-1.

[0116] 4. Synthesis of intermediate 2-1

[0117]

[0118] In a three-necked flask, 20 times intermediate 1-1 mass of tetrahydrofuran solvent and intermediate 1-1 (1 eq) were added, and after replacing nitrogen twice, the temperature was reduced to -78°C. Then under the atmosphere of nitrogen, n-butyllithium (3 eq) was added dropwise, and after the dropwise addition was completed, the stirring was carried out for 1 h at -78°C. Then dimethyldichlorosilane (3 eq) (CAS: 75-78-5) was slowly added to the three-necked flask, and the reaction was carried out for 3 h by slowly warming to room temperature. After the reaction was completed, the reaction liquid was poured into ice water for quenching, and then ethyl acetate was used for liquid separation, rotary evaporation and recrystallization to obtain the intermediate 2-1.

[0119] 5. Synthesis of formula I-9

[0120] .

[0121] In a three-necked flask, 15 times the mass of intermediate 2-1 of ethylene glycol ether and 3 times of water were added, then intermediate 2-1 was added, replaced with nitrogen twice, then added iridium trichloride, then under the protection of nitrogen, refluxed at 120℃ for 48h. After the reaction was completed, it was cooled to room temperature. Then by suction filtration, using anhydrous ethanol, petroleum ether was rinsed in turn, and finally dried to obtain intermediate 3-1.

[0122] In a three-necked flask, 10 times the mass of intermediate 3-1 of ethylene glycol ether was added, then intermediate 3-1 was added, replaced with nitrogen twice, then formula II-1 was added. Then under the protection of nitrogen, refluxed at 120℃ for 48h. After the reaction was completed, it was cooled to room temperature, suction filtered, washed with anhydrous ethanol and dried to obtain a compound with the structure shown in formula I-9.

[0123] Mass spectrometry test value: 1164.93. Nuclear magnetic resonance data is shown in Figure 1 .

[0124] The synthesis methods of other compounds are the same as described above, which will not be repeated here.

[0125] Device preparation example 1

[0126] 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:

[0127] 1. On the anode, the ITO patterned glass substrate was cut into a size of 50mm x 50mm x 0.5mm, washed with detergent for three times, 5 minutes each time, then ultrasonic treated with isopropanol, acetone in turn for 10 minutes, dried with nitrogen, and finally exposed to ultraviolet light and ozone for 30 minutes.

[0128] 2. The obtained glass substrate was loaded into a vacuum deposition device, first formula A was evaporated on the anode as a hole injection layer, the evaporation thickness was 100 angstroms. Then evaporate the first hole layer formula C, the thickness is 600 angstroms; then evaporate the electron blocking layer formula D, the evaporation film thickness is 50nm; the structural formulas of formula A, formula C, formula E are as follows:

[0129]

[0130]

[0131] 3. The host material 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP) and the compound of formula I-9 prepared in Example 1 were used as the dopant material to prepare the light-emitting layer in a mass ratio of 95:5, and the evaporation thickness was 400 angstroms. Then, a TPBI (formula E) electron transport layer with an evaporation thickness of 400 angstroms was evaporated on the light-emitting layer, an electron injection layer of LiF with an evaporation thickness of 10 angstroms was evaporated on the electron transport layer, and finally, a cathode material Al with an evaporation thickness of 1500 angstroms was evaporated on the electron injection layer, thereby obtaining an organic electroluminescent device.

[0132] Referring to Device Preparation Example 1, the compound of formula I-9 was replaced by compounds of formulas 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, which were respectively used as the dopant material of the light-emitting layer in the organic electroluminescent device, and were recorded as Device Preparation Examples 2-20. See Table 1 for details.

[0133] Device Comparative Examples 1-10

[0134] The organic electroluminescent device was prepared by the same method as in Device Preparation Example 1, except that the dopant material I-9 in the light-emitting layer was replaced by compounds 1-10, thereby obtaining Device Comparative Examples 1-10.

[0135] The structures of compounds 1-10 are shown below:

[0136] .

[0137] To further illustrate the luminescent performance of the iridium metal heterocyclic phosphorescent material prepared in the present application, the luminescent characteristics of the organic electroluminescent devices prepared in Device Preparation Examples 1-20 and the devices obtained in Device Comparative Examples 1-10 were tested. The measurement was performed using a KEITHLEY 2400 source measurement unit and a CS-2000 spectroradiometric luminance meter to evaluate the driving voltage, luminescent efficiency, and lifetime. The results of Device Comparative Example 1 were used as the benchmark, and the other data were normalized, and the results are shown in Table 1.

[0138] Table 1. Luminescent detection data of the organic electroluminescent device

[0139]

[0140]

[0141] As can be seen from Table 1, when the luminous brightness is 3000, the luminous efficiency and the service life of the devices of Preparation Examples 1-20 are longer, and the driving voltage is lower, as compared with the devices of Comparative Examples 1-6. This is because the six-membered heterocycle containing silicon or germanium in the structure causes the efficiency, the service life to increase, and the driving voltage to decrease.

[0142] 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 light-emitting 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, the steric hindrance effect is stronger, which further inhibits the molecular motion.

[0143] In addition, when the luminous brightness is 3000, the efficiency and the service life of the devices of Preparation Examples 1-20 are longer, and the driving voltage is lower, as compared with the devices of 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 reduces the exciton recombination efficiency, thereby reducing the efficiency. The multiple benzene rings are fused, which promotes the intermolecular π-π stacking, induces the diffusion and annihilation of excitons, and accelerates the aging of the light-emitting layer; the sulfur atom is easily oxidized at high temperature, which leads 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, which will cause the energy level of the transport layer to be out of adjustment, thereby requiring a higher voltage to maintain the current.

[0144] In summary, the organic electroluminescent device prepared by using the compound provided by the present application as a light-emitting layer doping material has a relatively low driving voltage, better luminous efficiency, and a longer service life.

[0145] The above description is only the preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can make equivalent replacements or changes to the technical solutions and concepts of the present application 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 metallo-heterocyclic phosphorescent dopant material, characterized by, A compound having a structure of Formula I: wherein X is selected from Si or Ge; X1, X2, and X3 represent carbon atoms, and X1 and X2 are connected by the following structure: ； Y1 and Y2 are carbon C; R1, R2, R3, R4substituents are the same or different, each independently selected from the group consisting of hydrogen, deuterium atom, halogen, cyano, substituted or unsubstituted C1-C 40 alkyl, substituted or unsubstituted C6aryl, substituted or unsubstituted C3-C7cycloalkyl, unsubstituted C1-C 10 silyl, unsubstituted C1-C 10 germyl, and combinations thereof; R a R c each independently selected from hydrogen, deuterium atom, halogen, cyano, substituted or unsubstituted C1-C 20 alkyl, substituted or unsubstituted C3-C 20 cycloalkyl, R a R c substituents at the positions are the same or different; The substituents in the "substituted" or "unsubstituted" are deuterium, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, t-butyl, n-pentyl, neopentyl, n-hexyl, cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyano, halogen, trimethylsilyl, and trimethylgermyl.

2. The iridium-containing metal heterocyclic phosphorescent dopant material of claim 1, wherein, the number of R1 substituents is 0-2, the number of R2 substituents is 0-3, the number of R3 substituents is 0-1, and the number of R4 substituents is 0-4.

3. The iridium-containing metallopolycycle phosphorescent dopant material of claim 1, wherein, The R1~R4, R a ~R c The hydrogen atoms in the substituent groups can be replaced by deuterium.

4. The iridium-containing metallopolycycle phosphorescent dopant material of claim 1, wherein, each of R1-R4 is independently selected from an alkyl group having 1-10 carbon atoms.

5. The iridium-containing metal heterocyclic phosphorescent dopant material of claim 1, wherein, each of R1-R4 is independently selected from a silyl group having 3-10 carbon atoms; each of R1-R4 is independently selected from a germyl group having 3-10 carbon atoms.

6. The iridium-containing metallopolycycle phosphorescent dopant material of claim 1, wherein, said R a ~R c each independently selected from the group consisting of wherein denotes the position of attachment of the radical.

7. An iridium metallo-heterocyclic phosphorescent dopant material, characterized in that, the structure of the iridium-containing metal heterocyclic phosphorescent dopant material is selected from any one of the following: 。 8. An organic electroluminescent device, characterized by The organic electroluminescent device comprises an anode, a cathode, and an organic functional layer disposed 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 comprises a host material and a dopant material, and the dopant material is the iridium-containing metal heterocyclic phosphorescent dopant material of any one of claims 1-7.

Images