Organic electroluminescent composition, luminescent layer, luminescent device and display device
By using thermally activated delayed fluorescence sensitizers and green fluorescent materials with specific structures in organic electroluminescent devices, the problem of insufficient roll-off of color purity, efficiency and efficiency in the prior art is solved, and a narrow spectrum, high color purity and high efficiency green light chromatic emission is achieved.
Patent Information
- Application Number
- CN202411905609.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-23
- Publication Date
- 2025-03-28
Smart Images
Figure CN119707779A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of electroluminescence, and in particular relates to an organic electroluminescent composition, a luminescent layer, a luminescent device, and a display device. Background Art
[0002] Organic Light Emission Diodes (OLED) are a type of device with a sandwich-like structure, including positive and negative electrode film layers and an organic functional material layer sandwiched between the electrode film layers. At present, organic electroluminescent materials mainly include three types: ordinary fluorescent materials, phosphorescent materials, and thermally activated delayed fluorescence (TADF) materials. Among them, TADF materials do not require the participation of heavy metal atoms to achieve 100% internal quantum efficiency, and have attracted widespread attention due to their low cost and environmental friendliness. TADF materials based on donor-acceptor structures often have a wider half-peak width of the emission spectrum, and the prepared devices often have low color purity. The multi-resonance TADF material developed in recent years has a narrow half-peak width of the emission spectrum, but its triplet exciton lifetime is longer, resulting in low efficiency of the device and a very serious efficiency roll-off.
[0003] In order to meet the new generation of display standards, new material systems must be developed to obtain OLED devices with high color purity, high efficiency, and low efficiency roll-off. Summary of the invention
[0004] The purpose of the present invention is to solve the deficiencies of the prior art. Based on this, the first aspect of the present invention provides an organic electroluminescent composition, comprising a thermally activated delayed fluorescence sensitizer and a luminescent material, wherein the structure of the thermally activated delayed fluorescence sensitizer is shown in Formula I; the luminescent material is a green fluorescent material, wherein the structure of the green fluorescent material is shown in Formula II, and the luminescent peak position of the green fluorescent material is 500nm-550nm, and the half-peak width is 15nm-40nm;
[0005]
[0006] In Formula I, R1, R2, R3, R4, R5, R6, R7 and R8 are independently selected from C1-C10 alkyl, C6-C18 aryl, C5-C18 heteroaryl and C1-C10 alkyl-substituted aryl;
[0007] In Formula II, R 11 , R 12 , R 13 , R 14 , R 21 , R 22 and R 23is independently selected from C1-C10 alkyl, C1-C10 alkoxy, C6-C18 aryl, C5-C18 heteroaryl, C6-C18 aryl substituted by C1-C10 alkyl, diphenylamino, carbazole, diphenylamino substituted by C1-C10 alkyl and carbazole substituted by C1-C10 alkyl; when containing aryl or heteroaryl, the aryl or heteroaryl forms a condensed ring structure with the adjacent structure or does not form a condensed ring structure; in Formula II, X 1 and X 2 independently selected from O, S, phenyl-substituted N, C1-C10 alkyl-substituted phenyl-substituted N, diphenylamino-substituted phenyl-substituted N and carbazolyl-substituted phenyl-substituted N; when containing phenyl, the phenyl group and R 10 , R 15 , R 21 and R 22 The sites are independent of each other to form a condensed ring structure or not; when the phenyl group and R 10 and R 15 When they are independent of each other and do not form a condensed ring structure, R 10 With R 15 Independently selected from hydrogen, C1-C10 alkyl, C1-C10 alkoxy, C6-C18 aryl, C5-C18 heteroaryl, C6-C18 aryl substituted by C1-C10 alkyl, diphenylamino, carbazolyl, diphenylamino substituted by C1-C10 alkyl and carbazolyl substituted by C1-C10 alkyl.
[0008] The present invention adopts a thermally activated delayed fluorescence sensitizer with a specific structure (the energy difference between the singlet state and the triplet state is not more than 0.2eV) and a green fluorescent material with a specific structure with a specially limited luminescence peak position of 500nm-550nm and a half-peak width of 15nm-40nm. The emission spectrum of the former overlaps very well with the absorption of the latter, so that the energy transfer is more complete, and green light with a narrow spectrum and high color purity is achieved. In addition, the device has higher efficiency, lower efficiency roll-off and longer service life.
[0009] In some preferred implementations, the thermally activated delayed fluorescence sensitizer is any one of compounds 1-47:
[0010]
[0011]
[0012]
[0013] More preferably, the thermally activated delayed fluorescence sensitizer is compound 7, compound 12 or compound 23. Its reverse intersystem crossing rate can reach 11.5*10 6 s -1 -12.8*10 6s -1 , its EQEmax can reach 36.4%-38.6%, its EQE@5K can reach 35.6%-37.1%, and its LT90@5K can reach 3672h-4126h.
[0014] The preparation method of the thermally activated delayed fluorescence sensitizer includes route 1 or route 2; the route 1 (used to synthesize the compound 1-25) is as follows:
[0015]
[0016] The above route 2 (used to synthesize the above compounds 26-47) is as follows:
[0017]
[0018] The second aspect of the present invention provides a light-emitting layer, comprising the above-mentioned organic electroluminescent composition. The above-mentioned thermally activated delayed fluorescence sensitizer accounts for 10%-50% (preferably 10%-30%) of the mass of the above-mentioned light-emitting layer, and the above-mentioned green fluorescent material accounts for 0.1%-20% (preferably 0.1%-10%) of the mass of the above-mentioned light-emitting layer. The above-mentioned light-emitting layer also includes a host material.
[0019] The third aspect of the present invention provides an organic electroluminescent device including the above-mentioned light-emitting layer. Specifically, the above-mentioned organic electroluminescent device also includes an anode, a cathode, a substrate and a functional layer, and the functional layer includes at least one of 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. Among them, the above-mentioned light-emitting layer and the hole injection layer, the hole transport layer, and the electron blocking layer can be prepared using a spin coating process or an inkjet printing process, and the electron transport layer, the electron injection layer and the cathode can be prepared using a vacuum evaporation process.
[0020] A fifth aspect of the present invention provides a display device comprising the above organic electroluminescent device.
[0021] The beneficial effects of the present invention are as follows: compared with existing materials, the organic electroluminescent composition proposed by the present invention has more complete energy transfer, higher device efficiency, better color purity, lower efficiency roll-off, and can make the prepared organic electroluminescent device have a longer service life. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 The figure shows the structure of an organic electroluminescent device. 1 is a substrate, 2 is an ITO anode, 3 is a hole transport layer, 4 is an electron blocking layer, 5 is a light-emitting layer, 6 is a hole blocking layer, 7 is an electron transport layer, 8 is an electron injection layer, and 9 is a metal cathode.
[0023] Figure 2 Shown is a schematic diagram of the overlap between the fluorescence spectrum of compound 23 and the absorption spectrum of the green fluorescent material tCzphB-Fl. DETAILED DESCRIPTION
[0024] The following will be combined with the embodiments and drawings to clearly and completely describe the concept, specific structure and technical effects of the present invention, so as to fully understand the purpose, scheme and effect of the present invention. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.
[0025] The structures of compounds 1-47 involved in the following contents are shown below:
[0026]
[0027]
[0028]
[0029] The synthetic route of compound 1-47 includes route 1 or route 2, wherein route 1 is as follows:
[0030]
[0031] Route 2 is as follows:
[0032]
[0033] In the following content, the structures of the compounds R1, R2, R3 and R4 are respectively as follows:
[0034] .
[0036] In addition, in the following content, the molecular mass spectrometry data (Mass Spectra: MS) was measured by ISQ7000 direct injection rod mass spectrometer of Thermo Fisher. The UV-visible absorption spectrum was measured by UV2600i UV-visible spectrophotometer of Shimadzu. The fluorescence spectrum was measured by RF6000 fluorescence photometer of Shimadzu, and the excitation wavelength selected during the test was the maximum absorption wavelength.
[0037] Example 1
[0038] A thermally activated delayed fluorescence sensitizer, the structure of which is shown in compound 23; and the preparation method thereof comprises the following steps:
[0039] (1) Synthesis of Compound M3
[0040] The reaction formula is as follows:
[0041]
[0042] The specific steps are as follows:
[0043] M1 (9.75 g, 30.0 mmol), M2 (8.57 g, 63.0 mmol), tetrakis(triphenylphosphine)palladium (Pd(PPh3)4: 1.04 g, 0.9 mmol) and potassium phosphate (31.84 g, 150.0 mmol) were added to 120 mL of dioxane, and then 30 mL of deionized water was added to the system, and the reaction was heated at 100°C for 48 hours. After the reaction was stopped, the reaction system was extracted with dichloromethane and water, and the extract was eluted with a dichloromethane / petroleum ether mixed solvent for column chromatography separation. The product M3 was 10.01 g of white solid, with a yield of 96%, and a mass spectrum of m / z 347.52 (M + ).
[0044] (2) Synthesis of Compound M6
[0045] The reaction formula is as follows:
[0046]
[0047] The specific steps are as follows:
[0048] M4 (6.21 g, 30.0 mmol), M5 (8.38 g, 33.0 mmol), [1,1'-bis(diphenylphosphino)ferrocene] dichloropalladium (Pd(dppf)Cl2: 0.66 g, 0.9 mmol) and potassium acetate (8.83 g, 90.0 mmol) were added to 150 mL of dry dioxane and heated at 85°C for 10 hours. After the reaction was stopped, the reaction system was extracted with dichloromethane and water, and the extract was eluted with a mixed solvent of dichloromethane / petroleum ether for column chromatography separation. The product M6 was 7.09 g of a white solid with a yield of 93%. The mass spectrum was m / z 254.15 (M + ).
[0049] (3) Synthesis of Compound M8
[0050] The reaction formula is as follows:
[0051]
[0052] The specific steps are as follows:
[0053] M6 (5.08 g, 20 mmol), M7 (2.08 g, 9.1 mmol), tris(dibenzylideneacetone)dipalladium (Pd2dba3: 366 mg, 0.4 mmol), SPhos (373 mg, 0.9 mmol) and potassium phosphate (9.65 g, 45.4 mmol) were added to 100 mL of dioxane, and then 20 mL of deionized water was added to the system, and the reaction was heated at 100 ° C for 24 hours. After the reaction was stopped, the reaction system was extracted with dichloromethane and water, and the extract was eluted with a mixed solvent of dichloromethane / petroleum ether for column chromatography separation. The product M8 was 2.01 g of white solid, with a yield of 55%, and a mass spectrum of m / z 402.22 (M + ).
[0054] (4) Synthesis of Compound 23
[0055] The reaction formula is as follows:
[0056]
[0057] The specific steps are as follows:
[0058] M4 (1.56 g, 4.5 mmol), M8 (402 mg, 1.0 mol) and potassium tert-butoxide (561 mg, 5.0 mmol) were added to 25 mL of DMF and heated at 130°C for 36 h. After the reaction stopped, the product was poured into 80 mL of water to precipitate a yellow-green precipitate, which was filtered off with suction. The filter cake was eluted with a mixed solvent of dichloromethane / petroleum ether and subjected to column chromatography separation. The product was 1.52 g of a light yellow-green solid, i.e., compound 23, with a yield of 89% and a mass spectrum of m / z 1711.78 (M + ).
[0059] Example 2
[0060] A thermally activated delayed fluorescence sensitizer, the structure of which is shown in compound 37; and a preparation method thereof comprises the following steps:
[0061] (1) Synthesis of Compound M10
[0062] The reaction formula is as follows:
[0063]
[0064] The specific steps are as follows:
[0065] M9 (6.21 g, 30.0 mmol), M5 (8.38 g, 33.0 mmol), Pd(dppf)Cl2 (0.66 g, 0.9 mmol) and potassium acetate (8.83 g, 90.0 mmol) were added to 150 mL of dry dioxane and heated at 85°C for 10 hours. After the reaction was stopped, the reaction system was extracted with dichloromethane and water, and the extract was eluted with a dichloromethane / petroleum ether mixed solvent for column chromatography separation. The product M10 was 6.78 g of a white solid with a yield of 89%. The mass spectrum was m / z 254.15 (M + ).
[0066] (2) Synthesis of Compound M11
[0067] The reaction formula is as follows:
[0068]
[0069] The specific steps are as follows:
[0070] M6 (6.10 g, 24.0 mmol), M7 (6.16 g, 20.0 mmol), Pd2dba3 (733 mg, 0.8 mmol), SPhos (821 mg, 2.0 mmol) and potassium phosphate (11.04 g, 52.0 mmol) were added to 150 mL of dioxane, and 30 mL of deionized water was added to the system, and the reaction was heated at 100 ° C for 24 hours. After the reaction was stopped, the reaction system was extracted with dichloromethane and water, and the extract was eluted with a mixed solvent of dichloromethane / petroleum ether for column chromatography separation. The product M11 was 4.32 g of white solid, with a yield of 73%, and a mass spectrum of m / z 354.02; 356.03 (M + ).
[0071] (3) Synthesis of Compound M12
[0072] The reaction formula is as follows:
[0073]
[0074] The specific steps are as follows:
[0075] M10 (2.44 g, 9.6 mmol), M11 (2.84 g, 8.0 mmol), Pd2dba3 (320 mg, 0.32 mmol), SPhos (329 mg, 0.8 mmol) and potassium phosphate (4.42 g, 20.8 mmol) were added to 90 mL of dioxane, and 16 mL of deionized water was added to the system, and the reaction was heated at 100 ° C for 24 hours. After the reaction was stopped, the reaction system was extracted with dichloromethane and water, and the extract was eluted with a dichloromethane / petroleum ether mixed solvent for column chromatography separation. The product M12 was 2.22 g of white solid, with a yield of 69%, and a mass spectrum of m / z 402.10 (M + ).
[0076] (4) Synthesis of Compound 37
[0077] The reaction formula is as follows:
[0078]
[0079] The specific steps are as follows:
[0080] M12 (1.21 g, 3.0 mmol), tert-butyl carbazole (3.77 g, 13.5 mol) and potassium tert-butoxide (1.68 g, 15.0 mmol) were added to 60 mL of DMF and heated at 130°C for 36 h. After the reaction stopped, the product was poured into 200 mL of water, and a yellow-green precipitate was precipitated. The filter cake was eluted with a mixed solvent of dichloromethane / petroleum ether and separated by column chromatography. The product was 4.78 g of a light yellow-green solid, i.e., compound 37, with a yield of 93% and a mass spectrum of m / z 1439.86 (M + ).
[0081] According to the similar synthesis method of Example 1 and Example 2, other compounds in Compounds 1-47 can be prepared. The analysis and characterization of some compounds are shown in Table 1.
[0082] Table 1
[0083] Compound Relative molecular weight <![CDATA[Molecular weight (M + )]]> Yield (%) Elemental analysis (%) 1 990.32 990.40 87 C,84.81; H,3.89; N,11.30 7 1102.45 1102.48 90 C, 84.91; H, 4.93; N, 10.16 13 1439.83 1439.84 90 C,85.06; H,7.17; N,7.77 19 1599.58 1599.64 91 C,88.57; H,4.45; N,6.98 23 1711.70 1711.78 89 C,88.35; H,5.11; N,6.52 32 990.32 990.41 90 C, 84.82; H, 3.87; N, 11.31 37 1439.83 1439.86 93 C,85.04; H,7.21; N,7.75 47 1599.58 1599.61 88 C,88.62; H,4.43; N,6.95
[0084] Example 3
[0085] An organic electroluminescent device (OLED device) having a structure as follows Figure 1 As shown, it includes in sequence: substrate 1, ITO anode 2, hole transport layer 3, electron blocking layer 4, light emitting layer 5, hole blocking layer 6, electron transport layer 7, electron injection layer 8, metal cathode 9. It is prepared by evaporation process.
[0086] Its specific structure is ITO (100nm) / TAPC (60nm) / TCTA (5nm) / mCPy: 20% sensitizer: 1% tCzphB-Fl (25nm) / CF3TRZ (5nm) / DPPyA (30nm) / LiF (0.5nm) / Al.
[0087] Among them, the structures of TAPC, TCTA, mCPy, tCzphB-Fl, CF3TRZ and DPPyA are shown below:
[0088]
[0089] The sensitizers are compounds 2, 7, 12 and 23 respectively; thus, device V, device VI, device VII and device VIII are prepared respectively.
[0090] In addition, the sensitizers are compounds R1, R3, and R4, respectively; thus, device II, device III, and device IV are prepared, respectively.
[0091] Comparative Example 1
[0092] An organic electroluminescent device (OLED device) is basically the same as that of Example 3, except that: no sensitizer is provided; and the composition of the light-emitting layer is mCPy: 1% tCzphB-Fl (25 nm).
[0093] Performance Testing
[0094] (1) Compound testing
[0095] Photophysical properties of some of the thermally activated delayed fluorescence sensitizers and compounds R1-R4 of the present invention were tested, and the results are shown in Table 2 and Figure 2 shown.
[0096] Table 2
[0097]
[0098] From Table 2 and Figure 2 It can be seen that the thermally activated delayed fluorescence sensitizer of the present invention has significantly enhanced intramolecular interactions and intramolecular spatial charge transfer characteristics compared to compounds with similar structures, and its wavelength is significantly red-shifted compared to R4; combined with Figure 2It can be seen that the red-shifted wavelength of the thermally activated delayed fluorescence sensitizer of the present invention increases the overlap of its luminescence spectrum with the absorption spectrum of the green fluorescent material with the specific luminescence peak position and half-width of the present invention, which is conducive to obtaining efficient energy transfer efficiency. In addition, the thermally activated delayed fluorescence sensitizer of the present invention also has a higher fluorescence quantum yield and a faster anti-system crossing rate (more significant than R1-R3). Therefore, when the thermally activated delayed fluorescence sensitizer of the present invention with a specific structure is used in combination with a specific structure green fluorescent material with a specific luminescence peak position and half-width as an electroluminescent composition for preparing an OLED device, higher efficiency and lower efficiency roll-off can be obtained.
[0099] (2) Performance test of organic electroluminescent devices (OLED devices)
[0100] The organic electroluminescent devices I-VIII prepared in Example 3 and Comparative Example 1 were tested. The current, voltage, brightness, luminescence spectrum and other characteristics of the devices were tested synchronously using a Photo Research PR 655 spectrum scanning luminance meter and a Keithley K2400 digital source meter system. The performance test of the device was carried out at room temperature and ambient atmosphere. The test results are shown in Table 3.
[0101] Table 3
[0102]
[0103] In Table 3, EQEmax represents the maximum external quantum efficiency, EQE@5K represents the external quantum efficiency when the luminous brightness is 5000nit, FWHM represents the half-peak width of the device luminous spectrum, CIE is the color coordinate of the device, and LT90@5K represents the lifespan of the device when the brightness decays to 90% when the initial brightness of the device is 5000nit.
[0104] As shown in Table 3, since the thermally activated delayed fluorescence sensitizer material of the present invention has a faster anti-system crossing rate, better energy transfer and higher fluorescence quantum yield, the device (V-VIII) prepared by using the sensitizer of the present invention with a specific structure green fluorescent material with a specific luminescence peak position and half-peak width has higher efficiency and lower efficiency roll-off than the device (I-IV) prepared by a similar structure compound. The color purity of the device is also substantially better than that of the comparative device. More importantly, the life of the device is also greatly improved. The above comparison shows that when the thermally activated delayed fluorescence sensitizer of the specific structure of the present invention is used as an electroluminescent composition for preparing an OLED device, the performance of the device can be comprehensively improved, and it is expected to be commercially promoted and used.
[0105] The above is only a preferred embodiment of the present invention. The present invention is not limited to the above implementation. As long as the technical effect of the present invention is achieved by the same means, it should belong to the protection scope of the present invention. Within the protection scope of the present invention, its technical scheme and / or implementation method can have various modifications and changes.
Claims
1. An organic electroluminescent composition, characterized in that: It comprises a thermally activated delayed fluorescence sensitizer and a luminescent material, wherein the structure of the thermally activated delayed fluorescence sensitizer is shown in Formula I; the luminescent material is a green fluorescent material, wherein the structure of the green fluorescent material is shown in Formula II, and the luminescent peak position of the green fluorescent material is 500nm-550nm, and the half-peak width is 15nm-40nm; In Formula I, R1, R2, R3, R4, R5, R6, R7 and R8 are independently selected from C1-C10 alkyl, C6-C18 aryl, C5-C18 heteroaryl and C1-C10 alkyl-substituted aryl; In Formula II, R 11 , R 12 , R 13 , R 14 , R 21 , R 22 and R 23 Independently selected from C1-C10 alkyl, C1-C10 alkoxy, C6-C18 aryl, C5-C18 heteroaryl, C6-C18 aryl substituted by C1-C10 alkyl, diphenylamino, carbazole, diphenylamino substituted by C1-C10 alkyl and carbazole substituted by C1-C10 alkyl; when containing aryl or heteroaryl, the aryl or heteroaryl forms a condensed ring structure with the adjacent structure or does not form a condensed ring structure; In Formula II, X 1 and X 2 independently selected from O, S, phenyl-substituted N, C1-C10 alkyl-substituted phenyl-substituted N, diphenylamino-substituted phenyl-substituted N and carbazolyl-substituted phenyl-substituted N; when containing phenyl, the phenyl group and R 10 , R 15 , R 21 and R 22 Independently form a condensed ring structure or do not form a condensed ring structure; when the phenyl group and R 10 and R 15 When they are independent of each other and do not form a condensed ring structure, R 10 With R 15 Independently selected from hydrogen, C1-C10 alkyl, C1-C10 alkoxy, C6-C18 aryl, C5-C18 heteroaryl, C6-C18 aryl substituted by C1-C10 alkyl, diphenylamino, carbazolyl, diphenylamino substituted by C1-C10 alkyl and carbazolyl substituted by C1-C10 alkyl.
2. The organic electroluminescent composition according to claim 1, characterized in that: The thermally activated delayed fluorescence sensitizer is any one of compounds 1-47:
3. The organic electroluminescent composition according to claim 2, characterized in that: The thermally activated delayed fluorescence sensitizer is compound 7, compound 12 or compound 23.
4. The organic electroluminescent composition according to claim 2, characterized in that: The preparation method of the thermally activated delayed fluorescence sensitizer includes route one or route two; the route one is as follows: The second route is as follows:
5. A light-emitting layer, characterized in that: The organic electroluminescent composition comprises the organic electroluminescent composition according to any one of claims 1 to 4.
6. The light-emitting layer according to claim 5, characterized in that Also includes the main material.
7. The light-emitting layer according to claim 5 or 6, characterized in that: The thermally activated delayed fluorescence sensitizer accounts for 10%-50% of the mass of the light-emitting layer, and the green fluorescent material accounts for 0.1%-20% of the mass of the light-emitting layer.
8. An organic electroluminescent device, characterized in that: The light-emitting layer comprises the light-emitting layer according to any one of claims 5 to 7.
9. The organic electroluminescent device according to claim 8, characterized in that: It also includes an anode, a cathode, a substrate and a functional layer, wherein the functional layer includes at least one of 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.
10. A display device, characterized in that: The organic electroluminescent device comprises the organic electroluminescent device according to claim 8 or 9.