An organic metal compound, an organic electroluminescent device comprising the same, and an application thereof

Abstract

The application belongs to the field of organic optoelectronic materials, and discloses an organic metal compound, an organic electroluminescent device containing the same and application. The structure of the organic metal compound is shown in formula I. The organic metal compound provided by the application can be used as a material in a light-emitting layer, can reduce the driving voltage of the device, and can prolong the service life of the device and improve the light-emitting efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of organic photoelectric materials, and in particular relates to an organic metal compound and an organic electroluminescent device containing the same. Background Art

[0002] Organic light emitting devices (OLEDs) utilize organic light emitting phenomena, which convert electrical energy into light energy using organic materials. These devices have characteristics such as wide viewing angle, excellent contrast, fast response time, excellent brightness, driving voltage, and response speed.

[0003] An organic light-emitting device typically has a structure including an anode, a cathode, and an organic material layer interposed between the anode and cathode. The organic material layer typically has a multilayer structure composed of different materials to improve the efficiency and stability of the organic light-emitting device. For example, the organic material layer may be formed from a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and the like. In the structure of an organic light-emitting device, if a voltage is applied between the two electrodes, holes are injected from the anode into the organic material layer, and electrons are injected from the cathode into the organic material layer. When the injected holes and electrons meet, excitons are formed, and when the excitons fall back to the ground state, light is emitted.

[0004] The light-emitting layer significantly impacts the efficiency and performance of organic light-emitting devices (OLEDs). Developing novel luminescent materials that meet practical requirements is crucial. However, due to the complex and time-consuming synthesis process of phosphorus-doped materials and their short lifespan, developing high-performance organic materials that enable OLEDs to achieve high efficiency, long lifespan, and low voltage is a pressing technical challenge facing researchers in this field. Summary of the Invention

[0005] In view of this, the present invention provides an organometallic compound and an organic electroluminescent device containing the same and its application. The organometallic compound provided by the present invention, when used as a material in the light-emitting layer of an organic electroluminescent device, can not only reduce the device's driving voltage but also extend the device's lifespan and improve its luminous efficiency.

[0006] In order to achieve the above purpose, the following technical solutions are adopted:

[0007] The first technical purpose of the present invention is to provide an organometallic compound having a structure shown in Formula I:

[0008] ,

[0009] wherein m is selected from 0, 1, and 2, and is preferably selected from 1;

[0010] X is selected from the following group: O, S, Se, -NR 19 、-C(R 20 R21 )、-Si(R 22 R 23 )、-Ge(R 24 R 25 ), where R 19 、R 20 、R 21 、R 22 、R 23 、R 24 、R 25 Each is independently selected from substituted or unsubstituted C3~C12 cycloalkyl, substituted or unsubstituted C1~C10 alkyl, substituted or unsubstituted C4~C18 aryl, and combinations thereof;

[0011] Ar1 is selected from phenyl and naphthyl, Ar2 is selected from a nitrogen-containing five-membered ring or a six-membered ring; Ra represents a single substitution to the maximum allowable substitution or no substitution; Rb represents a single substitution to the maximum allowable substitution or no substitution;

[0012] Ra and Rb are independently selected from hydrogen, deuterium, halogen, substituted or unsubstituted C1~C30 alkyl, substituted or unsubstituted C3~C20 cycloalkyl, substituted or unsubstituted C2~C10 heteroalkyl, substituted or unsubstituted C3~C12 heterocycloalkyl, substituted or unsubstituted C4~C12 heteroaryl, substituted or unsubstituted C6~C18 aryl, and combinations thereof, the heteroatom is selected from one or more of N, O, and S, and any two adjacent substituents may be linked to form a ring;

[0013] R1, R2, R3, R4, R5, R6, R7, R8, R 11 、R 12 、R 13 、R 14 、R 15 、R 16 、R 17 and R 18 are each independently selected from hydrogen, deuterium, halogen, substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C2-C12 heteroalkyl, substituted or unsubstituted C3-C12 heterocycloalkyl, substituted or unsubstituted C4-C12 heteroaryl, substituted or unsubstituted C4-C18 aryl, and combinations thereof, and the heteroatom is selected from one or more of N, O, and S, and R 11 、R 12 、R 13 and R 14 Two adjacent functional groups can be connected to form a ring;

[0014] R9 and R 10 Each is independently selected from hydrogen, deuterium, methyl and deuterated or fluorinated versions of methyl, ethyl and deuterated or fluorinated versions of ethyl.

[0015] Furthermore, R 19 、R 20 、R 21 、R 22 、R 23 、R 24 、R 25 Each is independently selected from methyl or partially deuterated methyl or fully deuterated methyl, ethyl or partially deuterated ethyl or fully deuterated ethyl, and fluoro.

[0016] The compound represented by Formula I can be used as a material in an organic material layer of an organic electroluminescent device, and can improve luminous efficiency, reduce driving voltage, extend life, and other characteristics in the organic electroluminescent device. In particular, the compound represented by Chemical Formula I can be used as a material for the light-emitting layer.

[0017] Preferably, the organometallic compound has the structure shown in the following formula I-1 or formula I-2: ,

[0018] X1, X2, X3, X4, X5, X6, X7, X8 and X9 are each independently selected from a carbon atom or a nitrogen atom.

[0019] Furthermore, ligand A ( ) is selected from the following structures: .

[0020] Furthermore, ligand B ( ) is selected from the following structures: ,

[0021] Rc and Rd are independently selected from hydrogen, deuterium, halogen, substituted or unsubstituted C1~C10 alkyl, substituted or unsubstituted C3~C10 cycloalkyl, substituted or unsubstituted C2~C10 heteroalkyl, substituted or unsubstituted C3~C8 heterocycloalkyl, substituted or unsubstituted C4~C12 heteroaryl, substituted or unsubstituted C4~C18 aryl, and the heteroatom is selected from one or more of N, O, and S;

[0022] Wherein, Rc is substituted to the maximum permissible substitution or no substitution on the benzene ring where it is located; Rd is substituted to the maximum permissible substitution or no substitution on the benzene ring where it is located; Y is selected from O, S, C (R 20 R 21 ), Si (R 22 R 23 )、Ge(R 24 R 25 ), preferably selected from O, Si (R 22 R 23 ), Ra, Rb, R 20 , R 21 , R 22 , R 23 , R 24 and R 25 The limitation is the same as above and will not be repeated here.

[0023] In the present invention, the terms "substituted or unsubstituted C1~C30 alkyl", "substituted or unsubstituted C3~C20 cycloalkyl", "substituted or unsubstituted C2~C10 heteroalkyl", "substituted or unsubstituted C4~C12 heteroaryl", "substituted or unsubstituted C6~C18 aryl", "substituted or unsubstituted C1~C15 alkyl", "substituted or unsubstituted C3~C20 cycloalkyl", "substituted or unsubstituted C2~C12 heteroalkyl", "substituted or unsubstituted C3~C12 heterocycloalkyl", "substituted or unsubstituted C4~C12 heteroaryl", "substituted or unsubstituted C4~C18 aryl", "substituted or The number of carbon atoms in the alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, aryl and heteroaryl groups in "unsubstituted C3~C12 cycloalkyl", "substituted or unsubstituted C1~C10 alkyl", "substituted or unsubstituted C4~C18 aryl", "substituted or unsubstituted C1~C10 alkyl", "substituted or unsubstituted C3~C10 cycloalkyl", "substituted or unsubstituted C2~C10 heteroalkyl", "substituted or unsubstituted C3~C8 heterocycloalkyl", "substituted or unsubstituted C4~C12 heteroaryl" and "substituted or unsubstituted C4~C18 aryl" represents the total number of carbon atoms constituting the unsubstituted carbon atoms, without taking into account the number of carbon atoms in the substituents.

[0024] Preferably, the "substituted" means substituted by one or at least two substituents selected from the group consisting of: deuterium, fluoro, cyano, isocyano, linear alkyl and deuterated or fluorinated variants thereof, branched alkyl and deuterated or fluorinated variants thereof, cycloalkyl and deuterated or fluorinated variants thereof, phenyl and deuterated variants thereof, and CF3.

[0025] In the above technical solution, the organometallic compound is selected from any one of the following structures: .

[0026] Only some specific structural forms are listed above, but this series of organometallic compounds is not limited to the above molecular structures. Any simple transformation of some simple groups and their substituted groups and substitution positions can obtain other specific molecular structures, which will not be listed here one by one.

[0027] The present invention also claims a method for preparing the above-mentioned organometallic compound (m is selected from 1), as shown below: ;

[0028] Step 1: Weigh raw materials A (2.2 eq), IrCl3•3H2O (1 eq), ethylene glycol ethyl ether (20 eq), and water (6.5 eq) and add them to a reactor. Replace nitrogen and reflux at 110°C–120°C for 40–48 hours. After the reaction is complete, cool to room temperature to allow precipitation to form. Filter the precipitate, rinse with anhydrous ethanol, and then dry with petroleum ether to obtain the bridging ligand A-1.

[0029] Step 2: Weigh the bridging ligand A-1 (1 eq), silver trifluoromethanesulfonate (2.2 eq), dichloromethane (20 eq), and methanol (4 eq) and add them to the reactor. Under nitrogen protection, react at room temperature for 40-48 hours. After the reaction is completed, filter through a silica gel funnel and spin dry to obtain intermediate A-2;

[0030] Step 3: Weigh the intermediate A-2 (1 eq), the intermediate TM1 (2.5 eq), N,N-dimethylformamide (DMF) (15 eq), and ethylene glycol ethyl ether (15 eq) and add them to the reactor, replace the nitrogen, react at 100-110°C for 40-48 hours, and after the reaction is completed, cool to room temperature, add (15-20 eq) of water to the system, and a precipitate is precipitated. The precipitate is filtered, and the filter cake is rinsed with ethanol and petroleum ether, dried, and subjected to column chromatography. Petroleum ether and dichloromethane are used as eluents, and the filtrate is concentrated to precipitate a solid to obtain an organometallic compound of formula I.

[0031] Experiments have shown that the above organometallic compounds, when used in organic electroluminescent devices, can significantly improve stability, increase luminous efficiency, increase lifespan, and reduce driving voltage.

[0032] A second technical objective of the present invention is to provide an organic electroluminescent device, comprising an organic layer; the organic layer contains the organometallic compound as described above.

[0033] Specifically, the organometallic compound may be in a single form or may be mixed with other substances and exist in the organic layer.

[0034] Furthermore, the organic electroluminescent device further comprises a first electrode and a second electrode; the organic layer is located between the first electrode and the second electrode; wherein the organic layer comprises a light-emitting layer, and the light-emitting layer comprises the organic metal compound as described above.

[0035] Furthermore, the light-emitting layer includes a host material and a doping material; the doping material includes the organic metal compound described above; and the mass ratio of the host material to the doping material is (10-99.5):0.5.

[0036] Generally speaking, the organic layer also includes one or more of a hole injection layer, a hole transport layer, a layer having both hole injection and hole transport functions, an electron blocking layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a layer having both electron transport and electron injection functions; wherein at least one functional layer contains the organic metal compound described in the present invention.

[0037] A third technical objective of the present invention is to provide an organic electroluminescent device for use in the preparation of an organic electroluminescent device, an organic solar cell, electronic paper, an organic photoreceptor, or an organic thin-film transistor. By introducing an organometallic compound into the light-emitting layer, the device is endowed with superior performance.

[0038] It can be seen from the above technical solutions that compared with the prior art, the present invention has the following beneficial effects:

[0039] 1) By introducing a nitrogen-containing five-membered ring or six-membered ring at the position of the phenyl group on the pyridine ring, the degree of conjugation of the system is increased, so that when the organometallic compound prepared by the present invention is applied to an organic electroluminescent device, the driving voltage is significantly reduced and the luminous efficiency is improved.

[0040] 2) Through R 11 、R 12 、R 13 and R 14Two adjacent functional groups are connected to form a ring, which increases the conjugation degree of the entire structure. When the organometallic compound prepared by the present invention is applied to an organic electroluminescent device, the driving voltage is significantly reduced and the luminous efficiency is improved.

[0041] 3) By introducing electron-withdrawing groups or electron-donating groups at different positions, the degree of conjugation of the system is increased and the steric hindrance effect is reduced. As a result, when the organometallic compound prepared by the present invention is applied to an organic electroluminescent device, the driving voltage is significantly reduced, the luminous efficiency is improved, and the life is extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0043] Figure 1 This is the H NMR spectrum of compound G-154. DETAILED DESCRIPTION

[0044] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention and the related drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0045] 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 value.

[0046] Reference common knowledge is as follows:

[0047] "Transition Metal Organic Chemistry" (Original Sixth Edition), Robert H. Crabtree, Publisher: Shanghai East China University of Science and Technology Press, Publication Date: 2017-09-00, ISBN: 978-7-5628-5111-0, page 388.

[0048] Organic Chemistry and Photoelectric Materials Experimental Tutorial, Chen Runfeng, Southeast University Press, 2019-11-00, ISBN: 9787564184230, page 174.

[0049] The embodiments of the present invention disclose a method for preparing an organometallic compound.

[0050] Example 1 Preparation of G-154

[0051]

[0052] Step 1: Weigh (4-(4,4-dimethylpiperidin-1-yl)phenyl)boronic acid (1.05 eq) (CAS: 2766475-50-5), 4-bromo-2-chloropyridine (1 eq) (CAS: 73583-37-6), toluene (10 eq), ethanol (5 eq), and water (5 eq). The atmosphere was replaced with nitrogen. Under nitrogen protection, tetrakis(triphenylphosphine)palladium (0.03 eq) was added to the system. The reaction was allowed to proceed at 80°C for 12 hours until the reaction was complete. The mixture was allowed to stand and separate. The aqueous phase was extracted with ethyl acetate, concentrated, and filtered through a silica gel funnel. The mixture was then purified by column chromatography using petroleum ether and dichloromethane as eluents and concentrated to provide intermediate S1 in a yield of 67.56%.

[0053]

[0054] Step 2: Weigh intermediate S1 (1 eq), 4-dibenzofuranboronic acid (1.1 eq) (CAS: 100124-06-9), toluene (10 eq), ethanol (5 eq), and water (5 eq). Nitrogen was replaced, and tetrakis(triphenylphosphine)palladium (0.03 eq) was added to the system under nitrogen protection. The reaction was allowed to proceed at 85°C for 12 hours, and the reaction was complete. The mixture was allowed to stand and separate. The aqueous phase was extracted with ethyl acetate, concentrated, and filtered through a silica gel funnel. The mixture was then purified by column chromatography using petroleum ether and ethyl acetate as eluents and concentrated to obtain intermediate S2 in a yield of 71.47%.

[0055]

[0056] Step 3: Weigh 2-phenylpyridine (CAS: 1008-89-5) (2.2 eq), IrC13•3H2O (CAS: 10025-83-9) (1 eq), ethylene glycol ethyl ether (20 eq), and water (6.5 eq) and add them to the reactor. Replace nitrogen and reflux at 120°C for 48 hours. After the reaction is completed, cool to room temperature and a precipitate will be precipitated. Filter the precipitate, rinse with anhydrous ethanol and petroleum ether in turn, and dry it to obtain the bridging ligand S3 with a yield of 91.25%.

[0057] Step 4: Weigh the bridging ligand S3 (1 eq), silver trifluoromethanesulfonate (2.2 eq), dichloromethane (20 eq), and methanol (4 eq) and add them to the reactor. Under nitrogen protection, react at 25°C for 48 hours. After the reaction is completed, pass through a silica gel funnel and spin dry to obtain intermediate S4 with a yield of 90.38%.

[0058]

[0059] Step 5: Intermediate S4 (1 eq), intermediate S2 (2.5 eq), N,N-dimethylformamide (DMF) (15 eq), and ethylene glycol ethyl ether (15 eq) were weighed and added to a reactor. The atmosphere was replaced with nitrogen and the reaction was carried out at 100°C for 48 hours. After the reaction was completed, the system was cooled to room temperature. Water (15 eq) was added to the system to produce a precipitate. The precipitate was filtered, and the filter cake was rinsed with ethanol and petroleum ether and dried. Column chromatography was performed using petroleum ether and dichloromethane as eluents. The filtrate was concentrated to obtain a solid precipitate, yielding organometallic compound G-154 in 26.35% yield.

[0060] HPLC: ≥99.2%.

[0061] Mass spectrum: Test value 933.49.

[0062] Elemental analysis: Test values ​​C, 67.05%; H, 4.67%; N, 5.98%; O, 1.75%.

[0063] NMR see attached Figure 1 .

[0064] The synthesis methods of other organometallic compounds are basically the same as those in the above embodiment and will not be described in detail here.

[0065] In order to further describe the present invention, more specific embodiments are listed below:

[0066] Device Example 1:

[0067] Fabrication of organic electroluminescent devices containing compound G-154

[0068] The ITO glass substrate with a coating thickness of 150nm was washed twice in distilled water and ultrasonically washed for 30 minutes, and then repeatedly washed twice with distilled water and ultrasonically washed for 10 minutes. After the distilled water washing was completed, the substrate was ultrasonically washed in sequence with isopropyl alcohol, acetone, methanol and other solvents, and then dried. The substrate was transferred to a plasma cleaning machine, washed for 5 minutes, and sent to a vapor deposition machine.

[0069] First, 70nm of 4,4',4"-tris[2-naphthylphenylamino]triphenylamine ("2-TNATA") was vacuum evaporated on the ITO (anode) as a hole injection layer. The structure of 2-TNATA is as follows; secondly, 70nm of N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB) was vacuum evaporated on the hole injection layer as a hole transport layer. The structure of NPB is as follows; the light-emitting layer was vacuum evaporated on the hole transport layer. The main material of the light-emitting layer, 4,4'-N,N'-biphenyldicarbazole (CBP), and the dopant compound G-154 were mixed in a weight ratio of 90:10. The light-emitting layer is formed by vacuum evaporation of 30nm, and the structure of CBP is as follows; then 20nm thick 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) is vacuum evaporated to form a hole blocking layer, and the structure of BCP is as follows; then 40nm thick 1,3,5-tris(4-pyridin-3-ylphenyl)benzene (TpPyPB) is vacuum evaporated on the hole blocking layer as an electron transport layer, and the structure is as follows; then 0.2nm thick lithium fluoride (LiF) is vacuum evaporated on the electron transport layer as an electron injection layer; and 150nm thick Al is vacuum evaporated on the electron injection layer as a cathode. An electroluminescent device is prepared in this way.

[0070] Under the condition of certain brightness, the performance and luminescence characteristics of the obtained electroluminescent device are tested to evaluate the driving voltage, luminescence efficiency and phosphorescence life.

[0071] The structure of the compound used in the device embodiment 1 is shown below: .

[0072] Device Example 2-32:

[0073] Organic electroluminescent devices of device examples 2-32 were prepared according to the preparation method of the organic electroluminescent device of device example 1, except that: the compound G-154 in device example 1 was replaced by G-6; G-13; G-22; G-28; G-29; G-35; G-46; G-71; G-92; G-122; G-141; G-162; G-165; G-173; G-191; G-209; G-290; G-318; G-427; G-447; G-473; G-560; G-587; G-642; G-717; G-752; G-782; G-799; G-818; G-849; G-852 to form doping material compounds.

[0074] Device Comparison

[0075] Organic electroluminescent devices of device comparison examples 1-6 were prepared according to the preparation method of the organic electroluminescent device of device example 1, except that the compound G-154 in device example 1 was replaced by comparative example 1, comparative example 2, comparative example 3, comparative example 4, comparative example 5, and comparative example 6, respectively, to form doping material compounds. .

[0076] The prepared organic electroluminescent device was subjected to the same tests as those in Device Example 1. The results are shown in Table 1.

[0077] Table 1

[0078]

[0079] As can be seen from Table 1, the organometallic compound provided by the present invention, as a light-emitting layer material of an organic electroluminescent device, can significantly reduce the driving voltage of the organic electroluminescent device, improve the luminous efficiency, and increase the life of the organic electroluminescent device, compared with the light-emitting layer materials currently used (such as Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5, and Comparative Example 6).

[0080] 1) By introducing electron-donating groups (such as methyl, ethyl, isopropyl, tert-butyl, etc.) at different positions of the single ligand, the electron cloud density is increased, the HOMO (highest occupied molecular orbital) energy level is increased, and the LUMO (lowest unoccupied molecular orbital) energy level is also increased. However, the increase in the HOMO energy level is greater, resulting in a smaller energy gap and the emission spectrum may be red-shifted. As a result, the driving voltage of the organic electroluminescent device prepared using the compound of the present invention is better than the driving voltage of the organic electroluminescent device prepared in the comparative example, the luminous efficiency is improved, and the life is significantly extended.

[0081] 2) By introducing electron-withdrawing groups (such as phenyl, substituted phenyl, etc.) at different positions of the single ligand, since the phenyl group has a larger conjugated system, the introduction can significantly expand the degree of conjugation of the molecule, thereby making the resulting compound more stable, resulting in a decrease in its electron cloud density, a decrease in the LUMO (lowest unoccupied molecular orbital) energy level, a larger energy gap, and the emission spectrum may undergo a red shift or a blue shift, resulting in a significant reduction in the driving voltage of the organic electroluminescent device prepared using the compound of the present invention and a significant improvement in the luminous efficiency.

[0082] 3) By introducing electron-withdrawing groups (such as fluorine and cyanide) at different positions within the single ligand, intermolecular forces are strengthened, molecular arrangement becomes more ordered, and the stability of the compound is improved. Fluorine's strong electron-withdrawing effect lowers the LUMO energy level, widens the energy gap, and causes a blue shift in the emission spectrum, improving luminescence efficiency. This also significantly reduces the driving voltage and extends the lifespan of organic electroluminescent devices prepared using the compounds of this invention.

[0083] 4) By introducing deuterium atoms and deuterated groups (such as -D, -CD3, -CD2CD3, -CD2CH3, etc.) at different positions of the single ligand, due to the large mass of deuterium, the introduction will reduce the vibration frequency of the molecule, enhance the rigidity of the molecular structure, reduce non-radiative transition orbits, and improve the luminous efficiency, resulting in a lower driving voltage of the organic electroluminescent device prepared using the compound of the present invention.

[0084] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one 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 present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An organometallic compound, characterized in that The organometallic compound is selected from one of the following structures:

2. An organic electroluminescent device, characterized in that: The organic electroluminescent device comprises an anode, a cathode, and an organic material layer disposed between the anode and the cathode; the organic material layer comprises the organometallic compound according to claim 1.

3. The organic electroluminescent device according to claim 2, characterized in that: The organic electroluminescent device comprises a light-emitting layer, and the light-emitting layer comprises a host material and a doping material; the doping material comprises the organic metal compound.

4. Use of the organic electroluminescent device according to claim 2 in the preparation of an organic electroluminescent device, an organic solar cell, an electronic paper, an organic photoreceptor or an organic thin film transistor.

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