Organometallic compound, organic electroluminescent device comprising same and application thereof

Abstract

The invention discloses an organic metal compound, an organic light-emitting device containing the organic metal compound and application of the organic light-emitting device. According to the organic metal compound, a specific heterocyclic ligand is introduced to be coordinated with iridium metal ions, and the organic metal compound with low energy is formed; functional groups such as substituted or unsubstituted methyl, substituted or unsubstituted ethyl, substituted or unsubstituted phenyl and the like are introduced to the position of a single ligand, so that after the obtained organic metal compound is applied to a luminescent layer material of an organic electroluminescent device, the driving voltage of the device can be reduced, the service life of the device can be prolonged, and the service life of the device is prolonged. The maximum external quantum efficiency is improved, and the stability is good.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic optoelectronic materials, and particularly relates to an organometallic compound, an organic electroluminescent device containing the same, and an application thereof. Background Art

[0002] An organic light emitting diode (OLED) is a light emitting device prepared by the recombination of electrons and holes in an organic thin film, and has the following advantages: (1) self-luminous, without the need for a backlight; (2) high brightness, high contrast, pure color, and almost no viewing angle problem; (3) ultra-thin, composed of a very thin organic material coating and a substrate material, small in volume and suitable for portable products; (4) very low power consumption, environmentally friendly and energy-saving; (5) fast response speed, one-thousandth of that of an LCD; (6) wide operating temperature range, and can still display normally at -40°C.

[0003] A general organic light emitting device (OLED) is composed of a cathode, an anode, and an organic layer inserted between the cathode and the anode. The device is composed of a transparent ITO anode, a hole injection layer (TIL), a hole transport layer (HTL), a light emitting layer (EL), a hole blocking layer (HBL), an electron transport layer (ETL), an electron injection layer (EIL), and a cathode such as LiAl.

[0004] The light emitting layer materials are divided into fluorescent materials and phosphorescent materials. The formation methods of the light emitting layer include a method of doping a phosphorescent material (organometal) in a fluorescent host material and a method of doping a fluorescent (nitrogen-containing organic compound) dopant in a fluorescent host material. Among them, heavy metal complexes have attracted great attention in the application research of organic light emitting diodes due to their high efficiency light emitting performance. The metal complexes used as organic light emitting diodes are mostly metal complexes of platinum (Pt), osmium (Os), and iridium (Ir). Among them, iridium metal complexes are the most effective, usually having an octahedral structure with a +3 oxidation state. The high efficiency phosphorescent emission is due to the strong spin-orbit coupling of the nuclear outer electron arrangement of the metal complex.

[0005] At present, the research on organic electroluminescent materials has been widely carried out in the academic and industrial fields, and a large number of organic electroluminescent materials with excellent performance have been developed one after another. However, the industrialization process of this technology still faces many key problems. How to design new light emitting materials containing iridium complexes with better performance for regulation has always been a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides an organometallic compound, an organic electroluminescent device containing the same, and its application. When the organometallic compound is used as a luminescent layer material of an organic light-emitting device, it can not only reduce the driving voltage of the device, but also delay the service life of the device and has good stability.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] The first technical object of the present invention is to provide an organometallic compound having a general formula shown in Formula I:

[0009]

[0010] Wherein, n can be selected from 1, 2 or 3;

[0011] La represents a bidentate ligand that can coordinate with iridium metal ions;

[0012] Ar represents a substituted or unsubstituted phenyl group, and is fused to any position of the ring where it is located;

[0013] X is independently selected from -C(CH 3 ) 2 -, -N-CH 3 , O, S, Se, -Si(CH 3 ) 2 -, -Ge(CH 3 ) 2 - or one or more of them;

[0014] Both Ra and Rc can be unsubstituted, mono-substituted, di-substituted, tri-substituted or tetra-substituted;

[0015] Both Rb and Rd can be unsubstituted, mono-substituted or di-substituted;

[0016] Both Ra and Rb are independently selected from one or more of hydrogen, deuterium, fluorine, methyl and deuterated methyl, ethyl and deuterated ethyl, propyl and deuterated propyl, isopropyl and deuterated isopropyl, butyl and deuterated butyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyano, phenyl;

[0017] Both Rc and Rd are independently selected from a hydrogen atom, deuterium, fluorine, cyano, substituted or unsubstituted C 1 -C 10 alkyl, substituted or unsubstituted C 1 -C 10 alkoxy, substituted or unsubstituted C 3 -C 24 cycloalkyl, substituted or unsubstituted C 6 -C 30 aryl, substituted or unsubstituted C6-30 Aryloxy, substituted C 3 -C 9 One or more of fluoro groups.

[0018] In one embodiment of the present invention, the organometallic compound has the structures shown in Formula I-a and Formula I-b:

[0019]

[0020] wherein, n is selected from 1 or 2;

[0021] R 1 、R 2 、R 3 、R 4 、R 5 、R 6 、R 7 、R 8 、R 11 、R 12 、R 13 and R 14 are each independently selected from methyl, ethyl, -CD 3 , propyl, butyl, phenyl, biphenyl, naphthyl, fluoro, cyano, deuterium, CF 3 ,

[0022]

[0023] R 9 and R 10 are each independently selected from a hydrogen atom, deuterium, methyl, ethyl, -CD 3 , -CDH 2 , -CD 2 H.

[0024] In one embodiment of the present invention, Formula I-a and Formula I-b are compounds having the structures shown in Formula I-1 to Formula I-14:

[0025]

[0026]

[0027] In one embodiment of the present invention, the ligand La (structural representation: ) is selected from the following structures LA-1 to LA-95:

[0028]

[0029]

[0030]

[0031] In one embodiment of the present invention, the structural formula of the organometallic compound is as shown in G-1 to G-738:

[0032]

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[0067]

[0068] The above only lists some specific structural forms, but the series of organometallic compounds are not limited to the above molecular structures. Any simple transformation of some simple groups, their substituted groups, and substitution positions can result in other specific molecular structures, which will not be elaborated one by one here.

[0069] In an embodiment of the present invention, the maximum emission wavelength of the organometallic compound having the structure shown in the general formula I is 500 nm to 560 nm. When the emission wavelength of the organic compound is within this range, after the organometallic compound is applied to an organic electroluminescent device, the driving voltage is significantly reduced and the lifespan is extended.

[0070] After the organometallic compound of the present invention is applied to an organic electroluminescent device, it can significantly improve the stability, extend the lifespan, and reduce the driving voltage.

[0071] The second technical object of the present invention is to provide an organic electroluminescent device, and the organic electroluminescent device includes an organic layer; the organic layer contains an organometallic compound having the structure shown in the general formula I.

[0072] In an embodiment of the present invention, the organometallic compound can be in a single form or mixed with other substances and present in the organic layer.

[0073] In an embodiment of the present invention, the organic electroluminescent device further includes a first electrode and a second electrode; the organic layer is located between the first electrode and the second electrode; wherein, the organic layer includes a light-emitting layer, and the light-emitting layer contains the organometallic compound as described above.

[0074] In an embodiment of the present invention, the light-emitting layer includes a host material and a doping material; the doping material contains an organometallic compound having a structure represented by General Formula I.

[0075] In an embodiment of the present invention, the mass ratio of the host material to the doping material is (10 - 99.5):0.5.

[0076] In an embodiment of the present invention, the organic layer further includes one or several functional layers such as a hole injection layer, a hole transport layer, an electron blocking layer, a hole blocking layer, an electron transport layer, and an electron injection layer; at least one of the functional layers contains the organometallic compound of the present invention.

[0077] Moreover, the third technical object of the present invention is to provide an application of an organometallic compound in the preparation of an organic electroluminescent device, an organic solar cell, an electronic paper, an organic photoreceptor, and an organic thin film transistor. By introducing the organometallic compound into the light-emitting layer, the device is endowed with more excellent performance.

[0078] According to the above technical solutions, compared with the prior art, the present invention has the following beneficial effects:

[0079] The organometallic compound provided by the present invention forms an organometallic compound with low energy by introducing a specific heterocyclic ligand to coordinate with iridium metal ions; by introducing functional groups (such as substituted or unsubstituted methyl, substituted or unsubstituted ethyl, substituted or unsubstituted phenyl, etc.) at the single ligand position, after the obtained organometallic compound is used in an organic electroluminescent device, the driving voltage is significantly reduced, the lifespan is prolonged, and the maximum external quantum efficiency is improved. Description of the Drawings

[0080] Figure 1 It is the nuclear magnetic resonance spectrum of G-272 prepared in Example 1. Detailed Embodiments

[0081] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0082] Example 1

[0083] Preparation of G-272

[0084]

[0085] Step 1: Weigh 4-bromodibenzofuran (1 eq), bis(pinacolato)diboron (2 eq), potassium acetate (2.5 eq), and 1,4-dioxane (40 eq) and add them to a reactor. Replace the nitrogen gas, and under nitrogen protection, add bis(dibenzylideneacetone)palladium (2% eq) and X-Phos (8% eq) to the system. React at 80 °C for 12 hours until the reaction is complete. Rotavaporize the reaction solution, filter it through a silica gel funnel, perform column chromatography, use petroleum ether and dichloromethane as the eluent, and concentrate to obtain intermediate S1 with a yield of 76%.

[0086]

[0087] Step 2: Weigh 2-bromonaphtho[2,3-d]oxazole (1 eq), intermediate S1 (1.2 eq), anhydrous potassium carbonate (3 eq), toluene (10 eq), ethanol (5 eq), and water (10 eq) and add them to a reactor. Replace the nitrogen gas, and under nitrogen protection, add tetrakis(triphenylphosphine)palladium (3% eq) to the system. React at 85 °C for 10 hours until the reaction is complete. Let it stand for liquid separation, combine the organic phases, filter through a silica gel funnel, perform column chromatography, use petroleum ether and ethyl acetate as the eluent, and concentrate to obtain intermediate S2 with a yield of 70.52%.

[0088] HPLC: ≥99.5%.

[0089] Mass spectrometry: Measured value 335.14

[0090]

[0091] Step 3: Weigh 2-phenyl-5-methylpyridine (2.2 eq), IrC1 3 ·3H 2 O (1 eq), ethylene glycol monoethyl ether (20 eq), and water (6.5 eq) and add them to a reactor. Replace the nitrogen gas, and reflux at 120 °C for 48 hours until the reaction is complete. Cool to room temperature, precipitate will form, filter the precipitate by suction, wash it successively with anhydrous ethanol and petroleum ether, and dry it to obtain the bridging ligand S3 with a yield of 87.6%.

[0092] 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 a reactor. Under nitrogen protection, react at room temperature for 48 hours until the reaction is complete. Filter through a silica gel funnel and rotavaporize to obtain intermediate S4 with a yield of 92.8%.

[0093]

[0094] Step 5: Weigh intermediate S4 (1 eq), intermediate S2 (2.5 eq), and absolute ethanol (15 eq) and add them to a reactor. Replace the nitrogen, and react at 80 °C for 48 hours until the reaction ends. Cool to room temperature, and a precipitate will form. Filter the precipitate by suction, wash the filter cake with ethanol and petroleum ether, and then dry it. Perform column chromatography with petroleum ether and dichloromethane as the eluent, concentrate the filtrate until a solid precipitates to obtain the organometallic compound G-272 with a yield of 34.75%.

[0095] HPLC: ≥99.5%.

[0096] Mass spectrometry: Measured value 863.32.

[0097] The NMR spectrum of G-272 is as Figure 1 shown.

[0098] The synthesis methods of other organometallic compounds are basically the same as those in the above embodiments and will not be elaborated one by one here.

[0099] To further describe the present invention, the following more specific embodiments are listed:

[0100] Device Example 1

[0101] Fabricate an organic electroluminescent device containing the organometallic compound G-272

[0102] Place an ITO glass substrate with a coating thickness of 150 nm in distilled water and wash it twice, perform ultrasonic washing for 30 minutes, then wash it repeatedly with distilled water twice and perform ultrasonic washing for 10 minutes. After the distilled water washing is completed, perform ultrasonic washing with solvents such as isopropanol, acetone, and methanol in sequence, dry it, transfer it to a plasma cleaner, wash the above ITO glass substrate for 5 minutes, and send it to an evaporation coater.

[0103] First, 60 nm of 4,4',4”-tris[2-naphthylphenylamino]triphenylamine (“2-TNATA”) is vacuum-evaporated on ITO (anode) as the hole injection layer, and the structure of 2-TNATA is as follows; second, 60 nm of N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (i.e., NPB) is vacuum-evaporated on the hole injection layer as the hole transport layer, and the structure of NPB is as follows; a light-emitting layer is vacuum-evaporated on the hole transport layer. The host material 4,4'-N,N'-biphenylcarbazole (i.e., CBP) of the light-emitting layer and the doping material compound G-272 are mixed in a weight ratio of 90:10 and vacuum-evaporated to form a 30-nm-thick light-emitting layer, and the structure of CBP is as follows; then 10 nm thick of BCP is vacuum-evaporated to form a hole blocking layer, and the structure of BCP is as follows; then 40 nm thick of TpPyPB is vacuum-evaporated on the hole blocking layer as the electron transport layer, and the structure is as follows; then 0.2 nm thick of LiF is vacuum-evaporated on it as the electron injection layer; then 150 nm thick of Al is vacuum-evaporated on the electron injection layer as the cathode. An electroluminescent device is prepared in this way. Under the condition of a certain brightness, the performance and luminescence characteristics of the obtained electroluminescent device are tested to evaluate the driving voltage and phosphorescence lifetime.

[0104]

[0105]

[0106] Example 2-22

[0107] The organic electroluminescent devices of Device Examples 2-22 are prepared according to the preparation method of the organic electroluminescent device of Device Example 1, except that the compound G-272 in Example 1 is replaced with G-1; G-3; G-4; G-8; G-26; G-33; G-68; G-72; G-92; G-116; G-144; G-176; G-274; G-277; G-293; G-307; G-320; G-332; G-490; G-494; G-509 to form the doping material compound.

[0108] Comparative Examples 1-5

[0109] The organic electroluminescent devices of Device Comparative Examples 1-5 are prepared according to the preparation method of the organic electroluminescent device of Device Example 1, except that the compound G-272 in Example 1 is replaced with Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, and Comparative Example 5 to form the doping material compound.

[0110]

[0111] The prepared organic light-emitting devices were tested in the same manner as in Device Example 1, and the results are shown in Table 1.

[0112] Table 1

[0113] Compound Drive Voltage (V) <![CDATA[Brightness (cd / cm 2 )]]> T95 (h) EQE (%) Comparative Example 1 6.17 10000 384 19.8 Comparative Example 2 5.12 10000 405 18.6 Comparative Example 3 4.89 10000 489 21.2 Comparative Example 4 4.72 10000 505 22.7 Comparative Example 5 4.69 10000 479 20.9 Comparative Example 6 4.55 10000 484 21.7 G-272 3.33 10000 702 34.3 G-1 3.41 10000 609 32.1 G-3 3.42 10000 628 33.2 G-4 3.37 10000 699 32.8 G-8 3.29 10000 604 34.6 G-26 3.21 10000 624 35.0 G-33 3.52 10000 590 33.1 G-68 3.35 10000 605 34.5 G-72 3.22 10000 588 35.1 G-92 3.35 10000 610 33.6 G-116 3.26 10000 651 31.5 G-144 3.43 10000 632 33.9 G-176 3.32 10000 681 32.8 G-274 3.31 10000 675 30.5 G-277 3.28 10000 696 35.1 G-293 3.23 10000 570 34.7 G-307 3.44 10000 675 30.4 G-320 3.36 10000 589 32.3 G-332 3.30 10000 606 31.3 G-490 3.43 10000 614 35.4 G-494 3.38 10000 556 30.6 G-509 3.25 10000 538 33.9

[0114] As can be seen from Table 1, when the organometallic compound of the present invention is used as the light-emitting layer material of the organic light-emitting device, compared with the existing light-emitting layer materials, the performance has been greatly improved, and the specific situation is as follows:

[0115] 1) Under the same brightness condition, the device test results show that compared with Comparative Example 1 and Comparative Example 2, when Compound G-272 is used as the light-emitting layer material of the organic light-emitting device, the driving voltage of the organic light-emitting device can be significantly reduced, the lifetime of the organic light-emitting device can be increased, and the external quantum efficiency is improved.

[0116] 2) Under the same brightness condition, the device test results show that compared with Comparative Example 3 and Comparative Example 4, when Compounds G-274, G-277, G-490, and G-494 are used as the light-emitting layer materials of the organic light-emitting device, the driving voltage of the organic light-emitting device can be significantly reduced, the lifetime of the organic light-emitting device can be increased, and the external quantum efficiency is improved.

[0117] 3) By changing the conjugation degree and electron cloud density of the ligand, the driving voltage of the organic light-emitting device can be increased.

[0118] 4) By introducing phenyl, biphenyl, fluoro group, etc. on the benzene ring with small steric hindrance of dibenzofuran, the driving voltage of the organic light-emitting device can be reduced, the lifetime of the organic light-emitting device can be increased, and the external quantum efficiency is improved.

[0119] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An organometallic compound, characterized in that The general formula having the structure shown in Formula I: wherein n is selected from 1, 2 or 3; La represents a bidentate ligand coordinated to the metal iridium ion; Ar is selected from substituted or unsubstituted phenyl and is fused to any position of the ring; X is independently selected from one of -C(CH3)2-, -N-CH3, O, S, Se, -Si(CH3)2-, -Ge(CH3)2-; Ra and Rc are both unsubstituted, monosubstituted, disubstituted, trisubstituted or tetrasubstituted; Rb and Rd are both unsubstituted, monosubstituted or disubstituted; Ra and Rb are independently selected from one or more of hydrogen, deuterium, fluorine, methyl and deuterated methyl, ethyl and deuterated ethyl, propyl and deuterated propyl, isopropyl and deuterated isopropyl, butyl and deuterated butyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyano, and phenyl; Rc, Rd are independently selected from hydrogen, deuterium, fluorine, cyano, substituted or unsubstituted C1-C 10 Alkyl, substituted or unsubstituted C1-C 10 Alkoxy, substituted or unsubstituted C3-C 24 Cycloalkyl, substituted or unsubstituted C6-C 30 Aryl, substituted or unsubstituted C 6-30 One or more of an aryloxy group and a substituted C3-C9 fluoro group.

2. The organometallic compound according to claim 1, characterized in that The organometallic compound has a structure shown in Formula Ia or Formula Ib: wherein n is selected from 1 or 2; R1, R2, R3, R4, R5, R6, R7, R8, R 11 , R 12 , R 13 and R 14 Each independently selected from methyl, ethyl, -CD3, propyl, butyl, phenyl, biphenyl, naphthyl, fluorine, cyano, deuterium, CF3, R9 and R 10 Each is independently selected from hydrogen atom, deuterium, methyl, ethyl, -CD3, -CDH2, -CD2H.

3. The organometallic compound according to claim 2, characterized in that The formula Ia and formula Ib are compounds of structures shown in formula I-1 to formula I-14:

4. The organometallic compound according to claim 1, characterized in that The specific structures of the ligand La include LA-1 to LA-95:

5. The organometallic compound according to claim 1, characterized in that The structures of the organometallic compounds are shown in G-1 to G-738:

6. The organometallic compound according to claim 1, characterized in that The maximum luminescent wavelength of the organic metal compound is 500nm to 560nm.

7. An organic electroluminescent device, characterized in that: The organic electroluminescent device comprises an organic layer; the organic layer comprises the organic metal compound having a structure represented by general formula I as claimed in any one of claims 1 to 6; the organic metal compound is in a single form or mixed with other substances and exists in the organic layer.

8. The organic electroluminescent device according to claim 7, characterized in that: The organic electroluminescent device 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 further includes a light-emitting layer, and the light-emitting layer includes a main material and a doping material; the doping material includes an organic metal compound with a structure shown in general formula I.

9. The organic electroluminescent device according to claim 7, characterized in that: The mass ratio of the main material to the doping material is (10-99.5):0.

5.

10. Use of the organometallic compound according to any one of claims 1 to 6 in the preparation of an organic electroluminescent device, an organic solar cell, an electronic paper, an organic photoreceptor and an organic thin film transistor.

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