Phosphorescent complex, preparation method thereof and organic electroluminescent device

Abstract

The application discloses a phosphorescent complex, a preparation method thereof and an organic electroluminescent device, and has the structural general formula: The phosphorescent complex provided by the application is combined by selecting specific heterocyclic ligands, the wavelength of the compound is adjusted, the phosphorescent complex obtained after being used in the organic electroluminescent device makes the organic electroluminescent device have higher current efficiency, lower driving voltage and longer phosphorescent lifetime. The preparation method of the phosphorescent complex provided by the application is simple and efficient, and the prepared product has high purity.

Description

Technical Field

[0001] This invention relates to the field of organic optoelectronic materials technology, and more specifically to a phosphorescent complex, its preparation method, and an organic electroluminescent device. Background Technology

[0002] In recent years, organic light-emitting diodes (OLEDs) have gained popularity due to their superior characteristics such as ultra-thinness, flexibility, self-illumination, and wide viewing angle. Currently, the efficiency and lifespan of green and yellow organic phosphorescent materials basically meet the needs of industrial production, but high-performance red phosphorescent materials still need to be developed.

[0003] In 1963, Pope's research group observed organic electroluminescence for the first time under vacuum conditions by passing a 400V DC current through micron-sized single-crystal anthracene vapor-deposited material. In 2011, Kwon's research group synthesized a red iridium complex, as shown in Formula 1, a phosphorescent complex. Using Bebq2 as the light-emitting host, the electroluminescent device achieved a maximum emission wavelength of 620nm, a low driving voltage of only 2.4V, CIE color coordinates of (0.64, 0.35), and a maximum current efficiency of 30.1cd / A. In 2017, Kido's research group synthesized a deep red phosphorescent complex, as shown in Formula 2, and used it as the host material to fabricate vapor-deposited optoelectronic devices with a maximum emission peak of 670nm, a driving voltage of 2.4V, and CIE color coordinates of (0.70, 0.29).

[0004]

[0005] The lack of high-efficiency red phosphorescent materials has been a major constraint on the rapid development of organic electroluminescent materials. In recent years, platinum complexes have been the most widely used red phosphorescent materials; however, due to their planar structure, platinum complexes are prone to aggregation, affecting their photoelectric properties. In contrast, octahedral iridium ring complexes possess characteristics such as short phosphorescence lifetime, high efficiency, simple synthesis, and easy adjustment of light color, making them a crucial research direction for designing novel, high-efficiency red phosphorescent materials. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a phosphorescent compound, a method for preparing the same, and an organic electroluminescent device. The application of the compound in electroluminescent devices and the organic electroluminescent devices prepared using this phosphorescent compound have high current efficiency, low driving voltage, and long phosphorescence lifetime.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A phosphorescent complex, the structure of which is shown in formula G:

[0009]

[0010] in:

[0011] R1 to R5 each independently represent hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, aralkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, thio, sulfinyl, sulfonyl, phosphine; or any adjacent substituents in R1 to R6 may optionally be joined or fused to form a ring;

[0012] The substituents of R1 to R3 can be located at any position on the ring, and the number of substituents of R1 to R3 is 0 to 4, while the number of substituents of R4 to R6 is 0 to 1.

[0013] Preferably, any adjacent substituents between R1 and R3 form a ring with each other, or R1 to R3 form a ring with other substituents on the ring, and any adjacent substituents between R4 and R6 form a ring with each other.

[0014] Preferably, the alkyl group is a straight-chain alkyl group, a branched alkyl group, a cycloalkyl group, a straight-chain alkyl group substituted with at least one substituent, a branched alkyl group substituted with at least one substituent, or a cycloalkyl group substituted with at least one substituent, wherein the substituent is independently selected from one or more combinations of deuterium, methyl, ethyl, isopropyl, nitro, halogen, and carboxyl.

[0015] Preferably, the aryl group is an unsubstituted aryl group or an aryl group substituted by at least one substituent; wherein the substituent is independently selected from one or more combinations of deuterium, nitro, halogen, nitrile, methyl, isopropyl, and tert-butyl.

[0016] Preferably, the heteroaryl group is an unsubstituted heteroaryl group or a heteroaryl group substituted by at least one substituent; wherein the heteroatom in the heteroaryl group is selected from one or more combinations of nitrogen, sulfur, or oxygen.

[0017] Preferably, the halogen is selected from one or more combinations of fluorine, chlorine, and bromine.

[0018] Preferably, the hydrogen atoms in the groups or substituents of R1 to R6 are deuterated.

[0019] Preferably, the specific structural formula of the phosphorescent complex shown in Chemical Formula 1 is as follows:

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027] The above are just some specific structural forms, but this series of compounds is not limited to the above molecular structures. Any other specific molecular structures can be obtained by simply changing these groups and the groups they replace and the substitution positions. These will not be elaborated on here.

[0028] The present invention also provides a method for preparing the above-mentioned phosphorescent complex, comprising the following steps:

[0029] S1. The compound iridium trichloride shown in Formula A is dissolved in ethylene glycol ethyl ether and water, and refluxed under inert gas protection for 20-36 hours. After the reaction is completed, the bridging ligand compound shown in Formula B is obtained by cooling, precipitation, filtration, washing and drying.

[0030] S2. The bridging ligand compound shown in Formula B, the diketone derivative shown in Formula C, anhydrous potassium carbonate, and ethylene glycol ethyl ether are sequentially added to a three-necked flask. Under inert gas protection, the reaction is carried out under reflux for 20-36 hours. After the reaction is completed, the phosphorescent complex shown in Formula G is obtained by cooling, precipitation, filtration, washing, drying, column chromatography, and concentration.

[0031] The synthetic route for phosphorescent complexes is as follows:

[0032]

[0033] Preferably, in step S1, the molar ratio of the compound represented by formula A to iridium trichloride is 2.5:1.

[0034] Preferably, in step S2, the molar ratio of the bridging ligand compound represented by formula B to the diketone derivative represented by formula C is 1:3.

[0035] Preferably, in step S1, the reaction temperature is 110-125℃.

[0036] Preferably, in step S2, the reaction temperature is 110-125℃.

[0037] Preferably, in step S1, the post-processing is as follows: then cooling to room temperature, a precipitate is formed, vacuum filtration is performed, followed by rinsing with anhydrous ethanol and petroleum ether in sequence, and drying to obtain the bridging ligand compound shown in Formula B.

[0038] Preferably, in step S2, the post-processing is as follows: cooling to room temperature, vacuum filtration, washing the filter cake with ethanol, drying at -0.1 MPa and 50°C, passing through a silica gel column, and evaporating the resulting filtrate to obtain the phosphorescent complex shown in formula G.

[0039] Preferably, the diketone derivative represented by formula C is selected from the following compounds:

[0040]

[0041] The present invention further provides the application of the above-mentioned phosphorescent complex in organic electroluminescent devices.

[0042] The present invention also provides an organic electroluminescent device comprising the above-mentioned phosphorescent complex.

[0043] The organic electroluminescent device includes: a first electrode, a second electrode, and at least one organic layer, the organic layer being located between the first electrode and the second electrode, and at least one of the organic layers containing a phosphorescent complex as described in any one of claims 1 to 7; the phosphorescent complex exists in the organic layer in a single form or mixed with other substances.

[0044] Preferably, the organic layer includes at least one or more of the following: a hole injection layer, a hole transport layer, a layer that has both hole injection and hole transport capabilities, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a layer that has both electron transport and electron injection capabilities.

[0045] Preferably, the organic electroluminescent device includes a light-emitting layer containing the aforementioned phosphorescent complex.

[0046] Preferably, the light-emitting layer includes a host material and a dopant material, the host material comprising a fluorescent host and a phosphorescent host, and the dopant material being the aforementioned phosphorescent complex.

[0047] Preferably, the mixing ratio of the host material to the dopant material is (90:10) to (99.5:0.5).

[0048] The present invention further provides the application of the above-mentioned organic electroluminescent device in organic light-emitting devices, organic solar cells, electronic paper, organic photoreceptors or organic thin film transistors.

[0049] As can be seen from the above technical solution, compared with the prior art, the present invention provides a phosphorescent complex, its preparation method, and an organic electroluminescent device, which have the following beneficial effects:

[0050] (1) The present invention provides a novel phosphorescent complex. Organic electroluminescent devices prepared using this phosphorescent complex have high current efficiency, low driving voltage and long phosphorescence lifetime.

[0051] (2) The preparation method of phosphorescent complex provided by the present invention is simple and efficient, and the prepared product has high purity. Detailed Implementation

[0052] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] Example 1

[0054] The specific steps for synthesizing compound G002 are as follows:

[0055]

[0056] S1. Weigh A-002 (55.68 mmol, 15.00 g), IrCl3·3H2O (22.28 mmol, 7.80 g), ethylene glycol ethyl ether (300 mL), and water (100 mL) and add them to the reaction system. Heat under reflux for 24 h under N2 protection, then cool to room temperature. A precipitate forms. Filter under reduced pressure, wash with anhydrous ethanol and petroleum ether successively, and dry to obtain B-002 (8.5 mmol, 13.00 g), with a yield of 76.5%.

[0057] S2. Weigh B-002 (8.50 mmol, 13.00 g), K2CO3 (85.02 mmol, 11.75 g), and ethylene glycol ethyl ether (100 mL) and add them to the reaction system. Under N2 protection, add C-002 (3,7-diethyl-4,6-nonanedione) (25.5 mmol, 5.41 g), heat to reflux for 24 h, cool to room temperature, filter under reduced pressure, wash the filter cake with ethanol, dry it at -0.1 MPa and 50 °C, pass it through a silica gel column, and evaporate the filtrate to dryness to obtain G-002 (10.52 mmol, 9.90 g), with a yield of 61.9%.

[0058] HPLC purity: >99%.

[0059] Mass spectrometry: theoretical value 940.22; measured value 940.36.

[0060] Elemental analysis:

[0061] Theoretical values: C, 67.71%; H, 5.47%; Ir, 20.44%; N, 2.98%; O, 3.40%;

[0062] Test values: C, 67.73%; H, 5.49%; Ir, 20.44%; N, 2.96%; O, 3.41%.

[0063] Example 2

[0064] The specific steps for synthesizing compound G-007 are as follows:

[0065]

[0066] S1. Weigh A-007 (50.43 mmol, 15.00 g), IrCl3·3H2O (20.17 mmol, 7.11 g), ethylene glycol ethyl ether (300 mL), and water (100 mL) and add them to the reaction system. Heat under reflux for 24 h under N2 protection, then cool to room temperature. A precipitate forms. Filter under reduced pressure, wash with anhydrous ethanol and petroleum ether successively, and dry to obtain B-007 (7.31 mmol, 12.00 g), with a yield of 72.4%.

[0067] S2. Weigh B-007 (7.31 mmol, 12.00 g), K2CO3 (73.08 mmol, 10.10 g), and ethylene glycol ethyl ether (100 mL) and add them to the reaction system. Under N2 protection, add C-007 (3,7-diethyl-4,6-nonanedione) (21.93 mmol, 4.64 g), heat to reflux for 24 h, cool to room temperature, filter under reduced pressure, wash the filter cake with ethanol, dry it at -0.1 MPa and 50 °C, pass it through a silica gel column, and evaporate the filtrate to dryness to obtain G-007 (8.02 mmol, 8.01 g), with a yield of 54.9%.

[0068] HPLC purity: >99%.

[0069] Mass spectrometry: theoretical value 996.33; measured value 996.42.

[0070] Elemental analysis:

[0071] Theoretical values: C, 68.72%; H, 5.97%; Ir, 19.29%; N, 2.81%; O, 3.21%;

[0072] Test values: C, 68.73%; H, 5.99%; Ir, 19.28%; N, 2.80%; O, 3.23%.

[0073] Example 3

[0074] The specific steps for synthesizing compound G-050 are as follows:

[0075]

[0076] S1. Weigh A-050 (47.56 mmol, 15.00 g), IrCl3·3H2O (19.02 mmol, 6.71 g), ethylene glycol ethyl ether (300 mL), and water (100 mL) and add them to the reaction system. Heat under reflux for 24 h under N2 protection, then cool to room temperature. A precipitate forms. Filter under reduced pressure, wash with anhydrous ethanol and petroleum ether successively, and dry to obtain B-050 (6.97 mmol, 12.00 g), with a yield of 75.1%.

[0077] S2. Weigh B-050 (6.97 mmol, 12.00 g), K2CO3 (69.68 mmol, 9.63 g), and ethylene glycol ethyl ether (100 mL) and add them to the reaction system. Under N2 protection, add C-050 (3,7-diethyl-4,6-nonanedione) (20.91 mmol, 4.43 g), heat to reflux for 24 h, cool to room temperature, filter under reduced pressure, wash the filter cake with ethanol, dry it at -0.1 MPa and 50 °C, pass it through a silica gel column, and evaporate the filtrate to dryness to obtain G-050 (7.26 mmol, 7.50 g), with a yield of 52.1%.

[0078] HPLC purity: >99%.

[0079] Mass spectrometry: theoretical value 1032.31; measured value 1032.40.

[0080] Elemental analysis:

[0081] Theoretical values: C, 66.32%; H, 5.57%; F, 3.68%; Ir, 18.62%; N, 2.71%; O, 3.10%;

[0082] Test values: C, 66.30%; H, 5.54%; F, 3.67%; Ir, 18.61%; N, 2.73%; O, 3.11%.

[0083] Example 4

[0084] The specific steps for synthesizing compound G-070 are as follows:

[0085]

[0086] S1. Weigh A-070 (43.80 mmol, 15.00 g), IrCl3·3H2O (17.52 mmol, 6.18 g), ethylene glycol ethyl ether (300 mL), and water (100 mL) and add them to the reaction system. Heat under reflux for 24 h under N2 protection, then cool to room temperature. A precipitate will form. Filter under reduced pressure, wash with anhydrous ethanol and petroleum ether successively, and dry to obtain B-070 (5.49 mmol, 10.00 g), with a yield of 64.57%.

[0087] S2. Weigh B-070 (5.49 mmol, 10.00 g), K2CO3 (54.84 mmol, 7.58 g), and ethylene glycol ethyl ether (100 mL) and add them to the reaction system. Under N2 protection, add C-070 (2,4,6-trimethyl-3,5-heptadecyl) (16.47 mmol, 2.77 g), heat to reflux for 24 h, cool to room temperature, filter under reduced pressure, wash the filter cake with ethanol, dry it at -0.1 MPa and 50 °C, pass it through a silica gel column, and evaporate the filtrate to dryness to obtain G-070 (5.45 mmol, 5.70 g), with a yield of 49.7%.

[0088] HPLC purity: >99%.

[0089] Mass spectrometry: theoretical value 1044.24; measured value 1044.34.

[0090] Elemental analysis:

[0091] Theoretical values: C, 62.11%; H, 4.92%; Ir, 18.41%; N, 5.37%; O, 9.19%;

[0092] Test values: C, 62.14%; H, 4.95%; Ir, 18.41%; N, 5.36%; O, 9.21%.

[0093] Example 5

[0094] The specific steps for synthesizing compound G-093 are as follows:

[0095]

[0096] S1. Weigh A-093 (39.86 mmol, 15.00 g), IrCl3·3H2O (15.94 mmol, 5.62 g), ethylene glycol ethyl ether (300 mL), and water (100 mL) and add them to the reaction system. Heat under reflux for 24 h under N2 protection, then cool to room temperature. A precipitate will form. Filter under reduced pressure, wash with anhydrous ethanol and petroleum ether successively, and dry to obtain B-093 (5.93 mmol, 11.00 g), with a yield of 74%.

[0097] S2. Weigh B-093 (5.93 mmol, 11.00 g), K2CO3 (59.33 mmol, 8.2 g), and ethylene glycol ethyl ether (100 mL) and add them to the reaction system. Under N2 protection, add C-093 (1,5-diphenyl-2,4-pentanedione) (17.79 mmol, 3.95 g), raise the temperature to 120 °C, heat under reflux for 24 h, cool to room temperature, filter under reduced pressure, wash the filter cake with ethanol, dry it at -0.1 MPa and 50 °C, pass it through a silica gel column, and evaporate the filtrate to dryness to obtain G-093 (6.17 mmol, 7.20 g), with a yield of 52.1%.

[0098] HPLC purity: >99%.

[0099] Mass spectrometry: theoretical value 1166.05; measured value 1166.13.

[0100] Elemental analysis:

[0101] Theoretical values: C, 60.77%; H, 3.89%; Br, 13.71%; Ir, 16.48%; N, 2.40%; O, 2.74%;

[0102] Test values: C, 60.74%; H, 3.83%; Br, 13.70%; Ir, 16.46%; N, 2.41%; O, 2.73%.

[0103] Example 6

[0104] The specific steps for synthesizing compound G-097 are as follows:

[0105]

[0106] S1. Weigh A-097 (45.26 mmol, 15.00 g), IrCl3·3H2O (18.10 mmol, 6.38 g), ethylene glycol ethyl ether (300 mL), and water (100 mL) and add them to the reaction system. Heat under reflux for 24 h under N2 protection, then cool to room temperature. A precipitate will form. Filter under reduced pressure, wash with anhydrous ethanol and petroleum ether successively, and dry to obtain B-097 (6.78 mmol, 12.05 g), with a yield of 74.6%.

[0107] S2. Weigh B-004 (6.75 mmol, 12.00 g), K2CO3 (67.51 mmol, 9.33 g), and ethylene glycol ethyl ether (100 mL) and add them to the reaction system. Under N2 protection, add C-097 (3,7-diethyl-4,6-nonanedione) (20.25 mmol, 4.29 g), raise the temperature to 120 °C, heat under reflux for 24 h, cool to room temperature, filter under reduced pressure, wash the filter cake with ethanol, dry it at -0.1 MPa and 50 °C, pass it through a silica gel column, and evaporate the filtrate to dryness to obtain G-097 (6.12 mmol, 6.51 g), with a yield of 45.2%.

[0108] HPLC purity: >99%.

[0109] Mass spectrometry: theoretical value 1064.30; measured value 1064.37.

[0110] Elemental analysis:

[0111] Theoretical values: C, 62.07%; H, 5.59%; Ir, 18.06%; N, 5.26%; O, 9.02%;

[0112] Test values: C, 62.08%; H, 5.60%; Ir, 18.07%; N, 5.27%; O, 9.03%.

[0113] Example 7-21

[0114] Following the synthesis method in Example 1, by simply replacing the corresponding reactants, the target compounds of Examples 7-21 can be synthesized. Their specific structural chemical formulas and MS (mass spectrometry) results are shown in Table 1.

[0115] Table 1. Chemical formulas and MS results of the target compounds in Examples 7-16.

[0116]

[0117]

[0118] Example 22

[0119] This embodiment provides an organic electroluminescent device, including a substrate, an anode layer disposed on the substrate, a hole injection layer disposed on the anode layer, a hole transport layer disposed on the hole injection layer, an organic light-emitting layer disposed on the hole transport layer, an electron transport layer disposed on the organic light-emitting layer, an electron injection layer disposed on the electron transport layer, and a cathode layer disposed on the electron injection layer.

[0120] The method for preparing the organic electroluminescent device is as follows:

[0121] The coating thickness is The ITO glass substrate was rinsed twice in distilled water, ultrasonically cleaned for 30 minutes, rinsed twice more in distilled water, and ultrasonically cleaned for 15 minutes. After the distilled water rinsing, it was ultrasonically cleaned in sequence with solvents such as isopropanol, acetone, and methanol, then dried and transferred to a plasma cleaner. The substrate was cleaned for 5 minutes and then sent to a vapor deposition machine. First, CuPc was vapor deposited on the ITO (anode). Following this, NPB was deposited by vapor deposition. Mixed vapor deposition of the host substance 4,4'-N,N'-biphenyldicarbazole ("CBP") and the dopant compound G-002 The weight ratio of CBP to the dopant compound G-002 is 95:5; the electron transport layer "Alq3" is deposited by vapor deposition. Evaporated electron-injected LiF layer Evaporated cathode Al Organic electroluminescent devices were prepared in this manner.

[0122] Following the method described above, G002 was replaced with G-001, G-007, G-010, G-013, G-026, G-035, G-041, G-045, G-050, G-052, G-055, G-063, G-070, G-075, G-080, G-086, G-090, G-093, G-097, and G-100, respectively, to prepare organic electroluminescent devices of the corresponding compounds.

[0123] Comparative Example 1

[0124] An organic electroluminescent device was prepared using the same method as in Example 22, except that the dopant compound G002 in the organic light-emitting layer was replaced with compound Ir(bty)2(acac). The resulting organic electroluminescent device has the following structural formula:

[0125]

[0126] To further illustrate the luminescence performance of the novel metallic iridium complex provided by this invention as a phosphorescent material, the performance and luminescence characteristics of the devices obtained in Example 22 and Comparative Example 1 were tested. The measurements were performed using a KEITHLEY 2400 source measurement unit and a CS-2000 spectroradiometer to evaluate the driving voltage, luminescence brightness, and luminescence efficiency. The results are shown in Table 2.

[0127] Table 2. Detection results of organic electroluminescent devices in Example 22 and Comparative Example 1.

[0128]

[0129]

[0130] As can be seen from Table 2, when the luminous intensity is 4000 cd / cm², 2 Compared with Comparative Example 1, the driving voltage of the device provided by the present invention is 3.92-4.56V, which is significantly lower than that of Comparative Example 1, while the efficiency (34.6-42.1) is much higher than that of Comparative Example 1, and the lifetime (641-745) is 4-5 times that of Comparative Example 1. It can be seen that the organic electroluminescent device prepared by using the phosphorescent complex provided by the present invention as the light-emitting layer material is superior to the organic electroluminescent device prepared by the comparative phosphorescent complex, with a significantly reduced driving voltage, significantly improved current efficiency, and significantly improved phosphorescence lifetime.

[0131] Those skilled in the art will readily recognize that many modifications and variations can be made to this invention without departing from its spirit and scope. Therefore, it is contemplated that this invention covers the modifications and variations provided within the scope of the appended claims and their equivalents.

[0132] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A phosphorescent complex, characterized in that, The structure of the phosphorescent complex is shown in formula G: The specific structural formula of the phosphorescent complex represented by chemical formula G is as follows: .

2. A method for preparing the phosphorescent complex according to claim 1, characterized in that, Includes the following steps: S1. Dissolve the compound shown in Formula A and iridium trichloride in a mixed solution of ethylene glycol ethyl ether and water, and carry out a reflux reaction under inert gas protection for 20-36 hours. After the reaction is completed, cool, precipitate, filter, wash and dry to obtain the bridging ligand compound shown in Formula B. S2. The bridging ligand compound shown in Formula B, the diketone derivative shown in Formula C, anhydrous potassium carbonate, and ethylene glycol ethyl ether are sequentially added to a three-necked flask. Under inert gas protection, the reaction is carried out under reflux for 20-36 hours. After the reaction is completed, the phosphorescent complex shown in Formula G is obtained by cooling, precipitation, filtration, washing, drying, column chromatography, and concentration. The synthetic route for phosphorescent complexes is as follows: 。 3. An application of the phosphorescent complex according to claim 1, characterized in that, Application of the phosphorescent complex in organic electroluminescent devices.

4. An organic electroluminescent device, characterized in that, The organic electroluminescent device includes a first electrode, a second electrode, and at least one organic layer located between the first electrode and the second electrode, and at least one of the organic layers contains the phosphorescent complex as described in claim 1; the phosphorescent complex exists in the organic layer in a single form or mixed with other substances.

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