Luminescent material, luminescent device, display panel and display device

Abstract

The invention discloses a light-emitting material, a light-emitting device, a display panel and a display device.The light-emitting material comprises a light-emitting compound, the light-emitting material has high T1 energy and has a higher LUMO energy level compared with an existing N-type main body material, the energy of an excimer formed between the light-emitting material and a P-type main body material or a doped material can be improved, and the light-emitting efficiency of the light-emitting material is improved. Therefore, the light-emitting efficiency of the light-emitting device can be improved, and the light-emitting color purity of the device can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of display, and particularly relates to a luminescent material, a light-emitting device, a display panel and a display device. Background Art

[0002] OLED blue phosphorescence has been studied for more than 20 years and has long troubled the OLED industry. Compared with blue fluorescence, blue phosphorescence can achieve an efficiency of about 1.5 times or more. However, due to the problem of lifespan, it cannot be applied in mass production. In OLED blue phosphorescent emission, the phosphorescent host material in the light-emitting layer material plays a very important role. Existing blue phosphorescent host materials have a high T1 energy level, and excitons are all concentrated on the doped material and can emit light. However, because the host material needs to have a higher T1 energy level than the doped material, the band gap between the materials becomes larger, and the charge in the light-emitting layer is unbalanced. Although some existing blue phosphorescent host materials have the characteristic of a high T1 energy level, they are difficult to meet the requirements of the luminescent material, and the luminescent effect of the luminescent material is not good. Summary of the Invention

[0003] The purpose of the embodiments of the present invention is to provide a luminescent material, a light-emitting device, a display panel and a display device to solve the problem that the existing phosphorescent materials have a poor luminescent effect.

[0004] In a first aspect, the embodiments of the present invention provide a luminescent material, including: a luminescent compound, and the structural formula of the luminescent compound is:

[0005]

[0006] Wherein, L1 represents an aromatic group, an aromatic group containing a heteroatom, or a single bond;

[0007] R1 to R2 are independently selected from an aromatic hydrocarbon, an aromatic group containing a heteroatom, a cyclic or acyclic hydrocarbon group with 1 to 80 carbon atoms, and a cyclic or acyclic silicon-containing compound group with 1 to 80 carbon atoms;

[0008] R3 to R6 are independently selected from an aromatic hydrocarbon, an aromatic group containing a heteroatom, a cyclic or acyclic hydrocarbon group with 1 to 80 carbon atoms, and a cyclic or acyclic silicon-containing compound group with 1 to 80 carbon atoms, and R3 - R6 are connected through a ring.

[0009] Optionally, the molecular weight of R1 to R6 is between 300 and 1200.

[0010] Optionally, the structural formula of the luminescent compound is selected from structural formula a1 to structural formula a10, and structural formula a1 to structural formula a10 are:

[0011]

[0012] Structural formula a1;

[0013]

[0014] Structural formula a2;

[0015]

[0016] Structural formula a3;

[0017]

[0018] Structural formula a4;

[0019]

[0020] Structural formula a5;

[0021]

[0022] Structural formula a6;

[0023]

[0024] Structural formula a7;

[0025]

[0026] Structural formula a8;

[0027]

[0028] Structural formula a9;

[0029]

[0030] Structural formula a10.

[0031] Optionally, the T1 energy level of the luminescent material is greater than or equal to 2.95 eV; and / or the LUMO range of the luminescent material is -1.6 to -1.8 eV.

[0032] In a second aspect, an embodiment of the present invention provides a light-emitting device, including:

[0033] The luminescent material described in the above embodiment.

[0034] Optionally, the light-emitting device includes:

[0035] A light-emitting layer, and the light-emitting layer includes the luminescent material.

[0036] Optionally, the light-emitting layer includes a host material and a guest material, and the host material is the luminescent material.

[0037] Optionally, the mass content of the host material in the light-emitting layer is 80-98%.

[0038] In a third aspect, an embodiment of the present invention provides a display panel, including:

[0039] The light-emitting device described in the above embodiment.

[0040] In a fourth aspect, an embodiment of the present invention provides a display device, including:

[0041] The display panel described in the above embodiment.

[0042] The light-emitting material of the embodiment of the present invention includes a light-emitting compound. The light-emitting material has a relatively high T1 energy and a higher LUMO energy level than the existing tri-azine series N-type host materials, which can increase the energy of the exciplex formed with the P-type host material or the doping material, thereby improving the light-emitting efficiency, increasing the light-emitting efficiency of the light-emitting device, and being beneficial to improving the color purity of the light emitted by the device. Description of the Drawings

[0043] Figure 1 It is a schematic structural diagram of a light-emitting device according to an embodiment of the present invention;

[0044] Figure 2 It is a spectrogram of a compound with structural formula a1;

[0045] Figure 3 It is a 1H NMR spectrum of the compound with structural formula a1 prepared in the present invention;

[0046] Figure 4 It is a 13C NMR spectrum of the compound with structural formula a1 prepared in the present invention.

[0047] Reference Signs

[0048] Anode 10; Hole injection layer 11; Hole transport layer 12; Electron blocking layer 13;

[0049] Cathode 20; Electron injection layer 21; Electron transport layer 22; Hole blocking layer 23;

[0050] Light-emitting layer 30. Detailed Embodiments

[0051] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. 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.

[0052] In the description and claims of the present invention, terms such as "first", "second", etc. are used to distinguish similar objects, rather than to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention can be implemented in an order other than those illustrated or described herein. In addition, "and / or" in the description and claims indicates at least one of the connected objects, and the character " / ", generally represents an "or" relationship between the associated objects before and after.

[0053] The luminescent material of the embodiment of the present invention includes: a luminescent compound, and the structural formula of the luminescent compound is:

[0054]

[0055] Wherein, L1 represents an aromatic group, an aromatic group containing a heteroatom, or a single bond;

[0056] R1 to R2 are independently selected from aromatic hydrocarbons, aromatic groups containing heteroatoms, cyclic or acyclic hydrocarbon groups having 1 to 80 carbon atoms, and cyclic or acyclic silicon-containing compound groups having 1 to 80 carbon atoms;

[0057] R3 to R6 are independently selected from aromatic hydrocarbons, aromatic groups containing heteroatoms, cyclic or acyclic hydrocarbon groups having 1 to 80 carbon atoms, and cyclic or acyclic silicon-containing compound groups having 1 to 80 carbon atoms, and R3 - R6 are connected by a ring.

[0058] The hydrogen in the luminescent compound can be entirely or partially replaced by deuterium.

[0059] The luminescent material of the embodiment of the present invention includes: a luminescent compound. The luminescent material has a relatively high T1 energy and a higher LUMO energy level than the existing tri-azine series N-type host materials, which can increase the energy of the exciplex formed with the P-type host material or the doping material, thereby improving the luminescence efficiency, increasing the efficiency of the light-emitting device, and being beneficial to improving the color purity of the device luminescence.

[0060] In some embodiments, the molecular weights of R1 to R6 are between 300 and 1200.

[0061] Optionally, the structural formula of the luminescent compound is selected from structural formula a1 to structural formula a10, and structural formula a1 to structural formula a10 are:

[0062]

[0063] Structural formula a1;

[0064]

[0065] Structural formula a2;

[0066]

[0067] Structural formula a3;

[0068]

[0069] Structural formula a4;

[0070]

[0071] Structural formula a5;

[0072]

[0073] Structural formula a6;

[0074]

[0075] Structural formula a7;

[0076]

[0077] Structural formula a8;

[0078]

[0079] Structural formula a9;

[0080]

[0081] Structural formula a10.

[0082] Optionally, the T1 energy level of the luminescent material is greater than or equal to 2.95 eV.

[0083] Optionally, the LUMO range of the luminescent material is -1.6 to -1.8 eV.

[0084] The LUMO and T1 values (quantum computing benchmarks) of some tri-azine series host materials are specifically shown in Table 1.

[0085] Table 1 LUMO and T1 values of some tri-azine series host materials

[0086]

[0087] When the tri-azine host material exists alone, it exhibits a short-wavelength spectrum of about 400 nm. However, when it is mixed with a P-type host material to form a single film, it exhibits a long-wavelength excimer spectrum. Moreover, if this wavelength is longer than that of the dopant, the energy of the host material cannot be transferred to the dopant normally, and the efficiency will decrease.

[0088] The light-emitting device according to an embodiment of the present invention includes:

[0089] The light-emitting material described in the above embodiment.

[0090] The light-emitting device having the light-emitting material according to an embodiment of the present invention has a high T1 energy for the light-emitting material in the device, a higher LUMO energy level than the existing tri-azine series N-type host material, and can improve the energy of the excimer formed between the P-type host material or the dopant, thereby improving the light-emitting efficiency of the device, improving the efficiency of the light-emitting device, and being beneficial to improving the color purity of the light emitted by the device.

[0091] In some embodiments, the light-emitting device may include:

[0092] A light-emitting layer, and the light-emitting layer may include the light-emitting material.

[0093] In some embodiments, as Figure 1 [[ID=2~]]As shown, the light-emitting device may include: an anode 10, a hole injection layer 11, an electron injection layer 21, and a cathode 20. The anode 10, the hole injection layer 11, the light-emitting layer 30, the electron injection layer 21, and the cathode 20 are stacked. A hole transport layer 12 may be provided between the anode 10 and the hole injection layer 11, and an electron transport layer 22 may be provided between the cathode 20 and the electron injection layer 21. An electron blocking layer 13 may also be provided between the hole transport layer 12 and the light-emitting layer 30, and a hole blocking layer 23 may also be provided between the electron transport layer 22 and the light-emitting layer 30. The thickness and material of the specific film layer can be selected according to needs.

[0094] Optionally, the light-emitting layer may include a host material and a guest material, and the host material may be the light-emitting material.

[0095] Optionally, the mass content of the host material in the light-emitting layer may be 80-98%. For example, the mass content of the host material in the light-emitting layer may be 98%, and the specific content can be selected according to the actual situation.

[0096] The display panel according to an embodiment of the present invention may include:

[0097] ]The light-emitting device described in the above embodiments. The display panel may include, but is not limited to, mobile phones, computers, tablets, in-vehicle screens, watches, etc. The display panel with the light-emitting device of the embodiment of the present invention can improve the light-emitting efficiency of the display panel and is beneficial to improving the color purity of the panel light emission.

[0098] The display device of the embodiment of the present invention includes:

[0099] The display panel described in the above embodiments. The display device may include, but is not limited to, digital tube displays, two-dimensional displays, three-dimensional displays, mechanical displays, etc. The display device with the display panel of the embodiment of the present invention can improve the light-emitting efficiency of the display panel and is beneficial to improving the color purity of the panel light emission.

[0100] The present invention will be further described below through some specific embodiments.

[0101] Prepare the compound with structural formula a1 of the present invention

[0102] The preparation method of the compound with structural formula a1 is as follows:

[0103]

[0104] Under a nitrogen atmosphere, add substance a (192.17 mmol), substance b (192.17 mmol), potassium carbonate (14.47 mmol), and tetrahydrofuran (100 ml) to a 500 ml three-necked flask in sequence, heat up to 75 °C, and carry out a reflux reaction for 9 h. After the system temperature drops to room temperature, pour the reaction solution into 1000 mL of deionized water, extract with dichloromethane, collect the organic phase, dry with anhydrous sodium sulfate, and concentrate to obtain a crude product. Subsequently, use toluene as the eluent, pass through a silica gel column to remove inorganic salts and excess catalysts and other impurities, and rotary evaporate and concentrate to obtain a crude product; the crude product is recrystallized with n-heptane / dichloromethane to finally obtain substance c (yield 62.23%).

[0105]

[0106] Under a nitrogen atmosphere, add substance c (38.27 mmol) and substance d (29.81 mmol) to a 500 mL three-necked flask in sequence, heat up to 65 °C to reflux, and stir and react for 5 h. After the system temperature drops to room temperature, add 200 mL of deionized water and stir for 5 minutes. After separating the organic phase, extract the aqueous phase with dichloromethane (200 mL × 3), combine the obtained organic phases and dry with anhydrous sodium sulfate, filter, and distill off the solvent under reduced pressure. The crude product is purified by silica gel column chromatography using n-heptane / dichloromethane as the eluent to finally obtain a white solid compound with structural formula a1 (8.61 g, yield 76.3%).

[0107] The compound with structural formula a1 prepared as described above for the present invention was analyzed. Figure 3 It is the 1H NMR spectrum of the compound with structural formula a1. Figure 3 The analysis of the 1H NMR spectrum in it is as follows: 1 H NMR(500MHz,Chloroform-d)δ8.28(t,J=2.1Hz,1H),7.99(ddd,J=9.3,2.1,1.2Hz,1H),7.81(ddd,J=8.4,2.1,1.2Hz,1H),7.69(dd,J=9.4,8.4Hz,1H),7.60–7.52(m,5H),7.43–7.33(m,7H),7.28(d,J=0.7Hz,2H),7.06–6.97(m,1H). Figure 4 It is the 13C NMR spectrum of the compound with structural formula a1. Figure 4 The analysis of the 13C NMR spectrum in it is as follows: 13C NMR(125MHz,Common NMR Solvents)δ168.11,166.41,142.44,139.46,137.78,137.66,134.52,134.13,131.47,130.62,129.89,129.18,127.69,127.27,127.02,124.58. Through spectrum analysis, it can be determined that the finally prepared compound is the compound with structural formula a1 to be prepared.

[0108] For the luminescent material in the present invention, while maintaining a high T1 energy level, the value of LUMO can be between -1.6 and -1.8 eV, as specifically shown in Table 2.

[0109] Table 2 Characteristics of Different Compounds

[0110]

[0111]

[0112] It can be seen that the luminescent material in the present invention has a relatively high T1 energy level. At the same time, the value of LUMO is between -1.6 and -1.8 eV, which can meet the requirements. The energy of the material of the present invention can be normally transferred to the doped material, improving the luminescence efficiency of the light-emitting device and being beneficial to improving the color purity of the device luminescence.

[0113] As Figure 2 shown, in Figure 2 it, curve k1 represents the spectrum of the compound with structural formula a1, curve k2 represents the spectrum of the mixture of the compound with structural formula a1 and the P-type host material, and curve k3 represents the spectrum of the blue phosphorescent dopant material. Through Figure 2It is demonstrated that the materials of the present invention can increase the energy of excimers formed between the P-type host materials or doped materials, thereby improving the luminescence efficiency, enhancing the luminescence efficiency of the light-emitting device, and being conducive to improving the color purity of the device luminescence.

[0114] In some embodiments, the organic light-emitting materials of the present application are used as blue phosphorescent host materials in organic electroluminescent devices. In the present application, there are no particular limitations on the specific types and structures of the organic electroluminescent devices. The light-emitting devices can be various types and structures of organic electroluminescent devices, and the materials of the light-emitting layer can use at least one of the light-emitting materials provided in the present application. The organic electroluminescent devices of the present application can be applied to light-emitting devices with a top-emitting structure, and can be sequentially stacked on a substrate: a first electrode (anode), a hole injection layer (HIL), a hole transport layer (HTL), a light-emitting layer (EML), an electron transport layer (ETL), an electron injection layer (EIL), and a second electrode (transparent or semi-transparent cathode).

[0115] In some embodiments, an electron blocking layer (EBL) can be provided between the hole transport layer and the light-emitting layer, a hole blocking layer (HBL) can be provided between the light-emitting layer and the electron transport layer, and a light extraction layer (CPL) can be provided on the transparent electrode on the light-emitting side. The structure of the organic electroluminescent devices of the present application is not limited to the above structure, and the above layers can be omitted or added as needed.

[0116] In the embodiments of the present invention, there are no limitations on the specific thickness and materials of the film layers in the light-emitting device. For example, in an organic electroluminescent device, a first electrode (anode) made of metal or metal oxide (with a thickness of 60 nm to 100 nm), a hole injection layer (with a thickness of 5 nm to 30 nm), a hole transport layer (with a thickness of 5 nm to 40 nm), an electron blocking layer (with a thickness of 5 nm to 15 nm), a light-emitting layer (with a thickness of 10 nm to 70 nm), a hole blocking layer (with a thickness of 5 nm to 20 nm), an electron transport layer (with a thickness of 5 nm to 40 nm), an electron injection layer (with a thickness of 1 nm to 6 nm), and a second electrode (transparent or semi-transparent cathode) (with a thickness of 60 nm to 150 nm) can be sequentially stacked on a substrate. For example, a first electrode (anode) made of metal or metal oxide (for example, with a thickness of 60 nm), a hole injection layer (with a thickness of 5 nm), a hole transport layer (with a thickness of 20 nm), an electron blocking layer (with a thickness of 6 nm), a light-emitting layer (with a thickness of 20 nm), a hole blocking layer (with a thickness of 15 nm), an electron transport layer (with a thickness of 20 nm), an electron injection layer (with a thickness of 4 nm), and a second electrode (transparent or semi-transparent cathode) (with a thickness of 80 nm) can be sequentially stacked on a substrate. The specific thickness of each film layer can be selected and adjusted according to the actual situation.

[0117] In the present application, the structure of the organic electroluminescent device can be stacked as follows: ITO (indium tin oxide) / HIL (HTL: P-Dopant) (10 - 20 nm, film thickness ratio 98%:2%) / HTL (80 - 110 nm) / EBL (5 - 10 nm) / EML: (SiCzCz: compound with structural formula a1: Pt dopant) (20 - 30 nm, film thickness ratio 7:3:10%) / HBL (5 - 10 nm) / ETL: LIQ (35 nm, (film thickness ratio 1:1)) / YB (1 - 5 nm) / Mg:Ag (11 nm, mass ratio 2:8) / CPL (50 - 70 nm). Among them, "film thickness ratio 98%:2%" means that the film thickness ratio of HTL to P-Dopant is 98%:2%; "film thickness ratio 7:3:10%" means that the vapor deposition film thickness of Pt dopant accounts for 10% of the total thickness of the light-emitting layer, the sum of the vapor deposition film thicknesses of SiCzCz and the compound with structural formula a1 accounts for 90% of the total thickness of the light-emitting layer, and the vapor deposition film thickness ratio of SiCzCz to the compound with structural formula a1 is 7:3.

[0118] Example 1

[0119] In Example 1 of the present application, a light-emitting device was prepared using the compound with structural formula a1. The compound with structural formula a1 was added to the light-emitting layer of the light-emitting device, and the performance of the prepared device was compared, as shown in Table 3 specifically.

[0120] In Example 1, the structure of the organic electroluminescent device can be stacked as follows: ITO (indium tin oxide) / HIL (HTL: P-Dopant) (10 nm, film thickness ratio 98%:2%) / HTL (110 nm) / EBL (5 nm) / EML: (SiCzCz: compound with structural formula a1: Pt dopant) (30 nm, film thickness ratio 7:3:10%) / HBL (5 nm) / ETL: LIQ (35 nm, (film thickness ratio 1:1)) / YB (1 nm) / Mg:Ag (11 nm, mass ratio 2:8) / CPL (70 nm). Among them, "film thickness ratio 98%:2%" means that the film thickness ratio of HTL to P-Dopant is 98%:2%; "film thickness ratio 7:3:10%" means that the vapor deposition film thickness of Pt dopant accounts for 10% of the total thickness of the light-emitting layer, the sum of the vapor deposition film thicknesses of SiCzCz and the compound with structural formula a1 accounts for 90% of the total thickness of the light-emitting layer, and the vapor deposition film thickness ratio of SiCzCz to the compound with structural formula a1 is 7:3.

[0121] Example 2

[0122] The difference between Example 2 and Example 1 is that:

[0123] Replace the compound with structural formula a1 with the compound with structural formula a2.

[0124] Test the performance of the light-emitting devices in Example 1 and Example 2 above. The specific test results are shown in Table 3.

[0125] Table 3 Test Results of the Performance of Organic Electroluminescent Devices

[0126]

[0127] It can be seen from Table 3 that the compound prepared by the present invention can effectively reduce the driving voltage, the efficiency remains at a normal level and the lifespan is improved. It is a blue phosphorescent host material with good performance.

[0128] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit of the present invention and the scope protected by the claims, and all of them fall within the protection scope of the present invention.

Claims

1. A luminescent material, characterized in that, Comprising: A luminescent compound, the structural formula of the luminescent compound being: Wherein, L1 represents an aromatic group, an aromatic group containing a heteroatom, or a single bond; R1 to R2 are independently selected from aromatic hydrocarbons, aromatic groups containing a heteroatom, cyclic or acyclic hydrocarbon groups having 1 to 80 carbon atoms, and cyclic or acyclic silicon-containing compound groups having 1 to 80 carbon atoms; R3 to R6 are independently selected from aromatic hydrocarbons, aromatic groups containing a heteroatom, cyclic or acyclic hydrocarbon groups having 1 to 80 carbon atoms, and cyclic or acyclic silicon-containing compound groups having 1 to 80 carbon atoms, and R3 - R6 are connected by a ring.

2. The luminescent material according to claim 1, characterized in that, The molecular weight of R1 to R6 is between 300 and 1200.

3. The luminescent material according to claim 1, wherein, The structural formula of the luminescent compound is selected from structural formula a1 to structural formula a10, and the structural formula a1 to structural formula a10 are: Structural formula a1; Structural formula a2; Structural formula a3; Structural formula a4; Structural formula a5; Structural formula a6; Structural formula a7; Structural formula a8; Structural formula a9; Structural formula a10.

4. The luminescent material according to claim 1, wherein The T1 energy level of the luminescent material is greater than or equal to 2.95 eV; and / or The LUMO range of the luminescent material is -1.6 to -1.8 eV.

5. A light-emitting device, characterized in that, Comprising: The luminescent material according to any one of claims 1 - 4.

6. The light-emitting device according to claim 5, characterized in that, The light-emitting device comprises: A light-emitting layer, the light-emitting layer comprising the luminescent material.

7. The light-emitting device according to claim 6, wherein, The light-emitting layer comprises a host material and a guest material, and the host material is the luminescent material.

8. The light-emitting device according to claim 7, wherein, The mass content of the host material in the light-emitting layer is 80 - 98%.

9. A display panel, characterized in that, Comprising: The light-emitting device according to any one of claims 5 - 8.

10. A display device, characterized in that, Comprising: The display panel according to claim 9.

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