Covering layer material, light-emitting device, display panel and display device

Abstract

The invention provides a covering layer material, a light-emitting device, a display panel and a display device. Wherein the structural formula of the covering layer material is as shown in the structural formula I in the specification. The covering layer material provided by the invention has a relatively high refractive index, is beneficial to improving the light emitting effect, can reduce the refractive index difference between blue light and red light, and improves the efficiency of overall white light, so that the product has a good display effect, and the product yield and the product competitiveness are improved. # imgabs0 #

Description

Technical Field

[0001] The present invention generally relates to the field of display technologies, and particularly relates to a cover layer material, a light-emitting device, a display panel, and a display device. Background Art

[0002] Currently used OLED devices mostly adopt a top-emitting device structure, with a reflective anode and a transparent cathode. The light extraction efficiency is enhanced through the microcavity effect. A cover layer (CPL) is introduced in the top-emitting device to increase the refractive index, forming a combination of high and low refractive indices above the cathode, thereby achieving a better light extraction effect. However, while the refractive index increases, the refractive index difference between blue light and red light also increases significantly, resulting in a still poor white light efficiency. Summary of the Invention

[0003] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a cover layer material, a light-emitting device, a display panel, and a display device. The cover layer material has a relatively high refractive index, can reduce the refractive index difference between blue light and red light, and improve the efficiency of overall white light.

[0004] In a first aspect, the present invention provides a cover layer material, and the structural formula of the cover layer material is as shown in Structural Formula I below:

[0005]

[0006] Wherein, ring A and ring B are each a phenanthrene ring;

[0007] L1, L2, and L3 are each independently selected from a single bond, a phenyl group, a biphenyl group, or a naphthyl group;

[0008] R1 and R2 are each independently selected from hydrogen, deuterium, an alkyl group having 1 to 5 carbon atoms, or an aryl group having 6 to 20 carbon atoms; the Ar group is selected from one of Structural Formulas II - IX;

[0009]

[0010] Wherein, X is selected from O or S, and Y is selected from C or N.

[0011] As an optional solution, at least one of the phenanthrene rings in ring A and ring B is connected at the 2-position.

[0012] As an optional solution, one of the phenanthrene rings in ring A and ring B is connected at the 2-position, and the other phenanthrene ring is connected at the 9-position.

[0013] As an optional solution, in Structural Formula I, except for the aromatic amine N atom, the number of other heteroatoms is less than or equal to 2, and the heteroatoms include N, O, or S.

[0014] As an optional solution, the number of heteroatoms in the Ar group is 0 or 1.

[0015] As an alternative, the structural formula of the cover layer material is one of the following:

[0016]

[0017]

[0018]

[0019] As an alternative, the refractive index difference between the cover layer material in blue light and red light is Δn, and Δn ≤ 0.48 * n(@460nm) - 0.868; where n(@460nm) is the refractive index of the cover layer material at a wavelength of 460 nm.

[0020] In a second aspect, the present invention provides a light-emitting device, comprising an anode, a light-emitting layer, a cathode, and a cover layer that are stacked;

[0021] The material of the cover layer is the cover layer material of the first aspect.

[0022] In a third aspect, the present invention provides a light-emitting device, comprising an anode, a light-emitting layer, a cathode, and a cover layer that are stacked;

[0023] The material of the light-emitting layer includes two host materials, and at least one hydrogen atom in the structural formula of at least one host material is replaced by deuterium;

[0024] Alternatively, at least one host material contains a heteroatom in its structural formula;

[0025] Alternatively, at least one hydrogen atom in the structural formula of at least one host material is replaced by deuterium and the structural formula contains a heteroatom.

[0026] The material of the cover layer is the cover layer material of the first aspect.

[0027] As an alternative, at least one hydrogen atom in the structural formula of one host material is replaced by deuterium, and the other host material contains a heteroatom in its structure;

[0028] Alternatively, at least one hydrogen atom in the structural formula of one host material is replaced by deuterium, and at least one hydrogen atom in the structural formula of the other host material is replaced by deuterium and the structural formula contains a heteroatom.

[0029] As an alternative, at least one hydrogen atom in the structural formula of one host material is replaced by deuterium, and the other host material contains a heteroatom O in its structure.

[0030] In a fourth aspect, the present invention provides a display panel, comprising the light-emitting device of the second aspect or the light-emitting device of the third aspect.

[0031] In a fifth aspect, the present invention provides a display device, including the display panel of the fourth aspect.

[0032] The covering layer material of the present invention includes an arylamine structure and a phenanthrene ring in its structural formula. The phenanthrene ring is a pure aryl group without heteroatoms. While increasing the polarizability of the covering layer material and improving the refractive index, it can reduce the difference between the refractive index of blue light and that of red light, which is beneficial to improving the white light efficiency. Moreover, Ar is a fused structure containing heteroatoms, and the fused structure can increase the conjugation of the structural formula, which is beneficial to further improving the refractive index, ensuring that the display panel has a good light-emitting effect, and at the same time being beneficial to improving the white light efficiency, so as to improve the display effect of the display panel, thereby improving the product yield and product competitiveness. Description of the Drawings

[0033] By reading the detailed description of the non-restrictive embodiments with reference to the following drawings, other features, objectives, and advantages of the present application will become more obvious:

[0034] Figure 1 It is a schematic structural diagram of a light-emitting device according to an embodiment of the present application;

[0035] Figure 2 It is a schematic structural diagram of another light-emitting device according to an embodiment of the present application.

[0036] In the figure, 1 is a substrate, 2 is a first electrode, 20 is a light-emitting layer, 3 is a hole injection layer, 4 is a hole transport layer, 5 is an electron blocking layer, 7 is a hole blocking layer, 8 is an electron transport layer, 9 is an electron injection layer, 10 is a second electrode, and 30 is a covering layer. Detailed Embodiments

[0037] The present application will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related invention, rather than limiting the invention. Additionally, it should be noted that for the sake of description, only the parts related to the invention are shown in the drawings.

[0038] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the drawings and embodiments.

[0039] In the related art, blue light emitting devices in OLED products are still the focus of development. Since blue light has high energy, its lifespan needs to be improved, and at the same time, a lower voltage needs to be maintained to reduce power consumption. Meanwhile, a cover layer (CPL) is introduced in the top-emitting device. Through a higher refractive index, a combination of high and low refractive indices is formed on the upper layer of the cathode, thereby achieving a better light extraction effect and improving efficiency. In order to increase the refractive index, CPL will introduce more heteroatoms into the structure, thereby increasing the polarizability. However, the problem brought about by this method is that while the refractive index increases, the difference in refractive indices between blue light and red light will also increase significantly. In OLED products, the device efficiencies of red, green, and blue colors need to be balanced, and then synthesized into white light efficiency. When the film thickness is the same, under blue light, a lower refractive index results in higher efficiency, while under red light, a higher refractive index results in higher efficiency. It can be seen that blue light requires a lower refractive index, while red light requires a higher refractive index. Therefore, if the refractive index of blue light is high while the refractive index of red light is very low, that is, the difference in refractive indices (Δn) between blue light and red light is large, even if the refractive index of blue light is high, the white light efficiency still cannot be improved. Due to the inherent properties of organic materials, the refractive index of blue light is higher and the refractive index of red light is lower. Therefore, materials with a higher refractive index while having a smaller difference in refractive indices (Δn) between blue light and red light have a very important impact on improving white light efficiency.

[0040] Based on the above, an embodiment of the present application provides a cover layer material, and the structural formula of the cover layer material is as shown in Structural Formula I below:

[0041]

[0042] Among them, ring A and ring B are each a phenanthrene ring;

[0043] L1, L2, and L3 are each independently selected from a single bond, a phenyl group, a biphenyl group, or a naphthyl group;

[0044] R1 and R2 are each independently selected from hydrogen, deuterium, an alkyl group having 1 to 5 carbon atoms, or an aryl group having 6 to 20 carbon atoms;

[0045] The Ar group is selected from one of Structural Formula II, Structural Formula III, and Structural Formula IV;

[0046]

[0047]

[0048] Among them, X is selected from O or S, and Y is selected from C or N.

[0049] It should be noted that in Structural Formula I, the middle is an aromatic amine structure, and L1, L2, and L3 are used as connecting structures, introducing two phenanthrene rings and a fused structure containing heteroatoms onto the aromatic amine structure respectively. Among them, the phenanthrene ring has three six-membered rings, and the six-membered rings form a conjugated system by sharing electron pairs. This conjugated structure is beneficial to increasing the polarizability and improving the refractive index. Moreover, the phenanthrene ring does not contain heteroatoms, which can reduce the difference between the refractive index of blue light and that of red light. A smaller refractive index difference can bring about a lower L-decay, thus improving the viewing angle problem; the fused structure of the Ar group is beneficial to further increasing the conjugation of the material and improving the refractive index, which is conducive to improving the light extraction effect.

[0050] In some embodiments, as shown in the following structural formula, any of the 10 positions on the phenanthrene ring can be connected to the aromatic amine. In a preferred embodiment, the aromatic amine structure is not connected to the 9th and 10th positions to avoid the existence of an angle between other structures and the benzene ring, reducing the conjugation degree and resulting in a lower refractive index.

[0051]

[0052] It can be understood that the C1-C5 alkyl group can be, but is not limited to, a C1-C5 straight-chain alkyl group, a C3-C5 branched-chain alkyl group, or a C3-C5 cycloalkyl group. Among them, the C1-C5 straight-chain alkyl group can be, but is not limited to, methyl, ethyl, propyl, sec-butyl, pentyl, etc.; the C3-C5 branched-chain alkyl group can be, but is not limited to, isopropyl, isobutyl, tert-butyl, isopentyl; the C3-C5 cycloalkyl group refers to an alkyl group having at least one ring, which can be a monocyclic alkyl group, such as, but not limited to, a three-membered ring, a four-membered ring, a five-membered ring, etc., such as, but not limited to, cyclopropyl, cyclobutyl, etc.;

[0053] The C6-C20 aryl group refers to a group containing at least one aromatic ring, and the aromatic ring can be a monocyclic aromatic ring (such as a benzene ring) or a polycyclic aromatic ring. In other words, the aromatic ring can be a monocyclic aromatic ring, a fused-ring aromatic ring, two or more monocyclic aromatic rings conjugated through carbon-carbon bonds, a monocyclic aromatic ring and a fused-ring aromatic ring conjugated through carbon-carbon bonds, or two or more fused-ring aromatic rings conjugated through carbon-carbon bonds. For example, but not limited to, phenyl, naphthyl, anthryl, acenaphthylenyl, indenyl, phenanthryl, azulyl, pyrenyl, fluorenyl, perylenyl, spirofluorenyl, spirobifluorenyl, benzophenanthryl, benzanthryl, fluoranthenyl, picenyl, tetraphenyl, indacenyl.

[0054] Among them, at least one hydrogen atom in the phenyl group, biphenyl group, naphthyl group, C1-C5 alkyl group, or C6-C20 aryl group can be substituted by a substituent;

[0055] Substituted phenyl means that at least one hydrogen atom in the phenyl group can be substituted by a substituent; substituted biphenyl means that at least one hydrogen atom in the biphenyl group can be substituted by a substituent; substituted naphthyl means that at least one hydrogen atom in the naphthyl group can be substituted by a substituent;

[0056] Substituted C1-C5 alkyl means that at least one hydrogen atom in the group can be substituted by a substituent; substituted C6-C20 aryl means that at least one hydrogen atom in the group can be substituted by a substituent.

[0057] It can also be understood that in the Ar group, the number of heteroatoms can be 0, one, two, three, four, etc. In some embodiments, the number of heteroatoms in the Ar group is preferably less than or equal to two, so as to avoid a large difference in the refractive index between blue light and red light.

[0058] In the covering layer material of the embodiment of the present application, the structural formula of the covering layer material includes an arylamine structure and a phenanthrene ring, wherein the phenanthrene ring is a pure aryl group without heteroatoms. While increasing the polarizability of the covering layer material and improving the refractive index, it can reduce the difference between the refractive index of blue light and the refractive index of red light, which is beneficial to improving the white light efficiency; and, Ar is a fused structure containing heteroatoms, and the fused structure can increase the conjugation of the structural formula, which is beneficial to further increasing the refractive index, ensuring that the display panel has a good light-emitting effect, and at the same time is beneficial to improving the white light efficiency to improve the display effect of the display panel, thereby improving the product yield and product competitiveness.

[0059] In some embodiments, at least one phenanthrene ring in ring A and ring B is connected at the 2-position.

[0060] Among them, the phenanthrene ring of ring A can be connected at the 2-position, or the phenanthrene ring of ring B can be connected at the 2-position, or the phenanthrene rings of both ring A and ring B are connected at the 2-position.

[0061] In this embodiment, the connection at the 2-position of the phenanthrene ring is beneficial to increasing the conjugated structure, further increasing the polarizability of the covering layer material, and improving the refractive index.

[0062] In some embodiments, one phenanthrene ring in ring A and ring B is connected at the 2-position, and the other phenanthrene ring is connected at the 9-position.

[0063] In some embodiments, in structural formula I, except for the arylamine N atom, the number of other heteroatoms is less than or equal to 2, and the heteroatoms include N, O or S.

[0064] In this embodiment, it is beneficial to reduce the number of heteroatoms in the covering layer material. The smaller the number of heteroatoms, the smaller the difference between the refractive index of blue light and the refractive index of red light, which is beneficial to improving the white light efficiency.

[0065] In a preferred embodiment, the number of heteroatoms in the Ar group is 0 or 1.

[0066] In this embodiment, the number of heteroatoms is small. While increasing the refractive index of the entire capping layer material, it can also reduce the difference between the refractive index of blue light and the refractive index of red light, thereby facilitating the improvement of white light efficiency.

[0067] As an achievable manner, the structural formula of the capping layer material is one of the following:

[0068]

[0069]

[0070]

[0071]

[0072]

[0073] The following uses specific examples to illustrate the synthesis method of the material of the capping layer provided by the embodiments of the present application:

[0074] Example

[0075] The following is the synthesis process of a compound 1 provided in this embodiment:

[0076] Synthesis of intermediate 1-1:

[0077] In a 1,4-dioxane solution in the presence of nitrogen, 2-bromophenanthrene (38.57 g, 150 mmol), 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)aniline (32.86 g, 150 mmol), Pd(PPh 3 ) 2 Cl 2 (1.05 mg, 1.5 mmol) and sodium carbonate (0.32, 3 mmol) were added, and the mixture was stirred and reacted at 80 °C for 12 hours. After filtration, intermediate 1-1 was obtained (yield 74%).

[0078]

[0079] Synthesis of intermediate 1-2:

[0080] Toluene solvent (150 mL) was added to the reaction flask, and then 4-(phenanthren-2-yl)aniline (26.94 g, 100 mmol), 2-(4-bromophenyl)phenanthrene (33.32 g, 20 mmol) and sodium tert-butoxide (14.42 g, 150 mmol) were added; after purging with nitrogen, Pd 2 (dba)3 (0.92 g, 1 mmol), Sphos (0.82 g, 2 mmol) was added; it was refluxed for 2 hours under nitrogen gas filling, filtered by suction and washed with methanol to obtain a recrystallized solid, and intermediate 1-2 was obtained (yield 91%).

[0081]

[0082] Synthesis of Compound 1:

[0083]

[0084] Toluene solvent, intermediate 1-2 (41.73 g, 80 mmol), 3-bromobenzo[d]naphtho[3,2-b]furan (23.77 g, 80 mmol), and sodium tert-butoxide (11.53 g, 120 mmol) were added successively; after filling with nitrogen gas, Pd 2 (dba) 3 (0.73 g, 0.8 mmol) was added, and Sphos (0.66 g, 1.6 mmol) was added; the nitrogen gas filling process was repeated, refluxed for 2 hours. After the reaction was completed, it was cooled to room temperature, filtered through diatomaceous earth to obtain a filtrate, concentrated, heated, a small amount of ethanol was added, allowed to stand at room temperature for recrystallization, filtered by suction and washed with ethanol to obtain a recrystallized solid, and Compound 1 was obtained, which was a pale yellow solid, purity: 99.51%, yield: 88%, MS: 737.88; C 56 H 35 NO.

[0085] The synthesis processes of other compounds are similar to that of Compound 1. Several intermediates used in the synthesis processes of compounds are shown in Table 1 below:

[0086] Table 1 Intermediates for Compound Synthesis

[0087]

[0088]

[0089]

[0090] The comparative materials are as follows:

[0091]

[0092]

[0093] The materials of the above-mentioned examples and the comparative examples were tested respectively. The refractive index n, absorption coefficient k, and the difference in peak value were compared at three common wavelengths of 460 nm, 530 nm, and 620 nm respectively. Among them, the absorption coefficient was measured by ellipsometry. The scanning range of the instrument was 245 - 1000 nm. A silicon wafer was used to deposit a thin film, and the thickness of the material thin film was 50 nm. The glass transition temperature was tested by DSC, and the second heating process was selected, with the temperature ranging from room temperature to 300 °C. The test results of the refractive index are shown in Table 2 below.

[0094] Table 2 Refractive Index of the Compounds in the Examples of the Present Application and the Materials of the Comparative Examples

[0095]

[0096]

[0097] From the test results in Table 2, it can be obtained that the refractive index difference between blue light and red light of the covering layer material in the examples of the present application is Δn, and Δn = n(@460 nm) - n(@620 nm);

[0098] According to the refractive index data of the covering layer material, a fitting curve was obtained and the following relationship was derived: Δn ≤ 0.48 * n(@460 nm) - 0.868.

[0099] In Comparative Example CP-1, since the material does not contain any heteroatoms and the substituent contains biphenyl, the refractive index is lower compared to phenanthrene and naphthalene in this solution. In Comparative Example CP-2, it contains a dibenzofuran structure connected to benzene, and the conjugation of this structure is relatively low, so the refractive index is lower. Comparative Example CP-3 contains two naphthalenes, and the conjugation degree of naphthalene is smaller than that of phenanthrene, so the refractive index is lower. Comparative Example CP-4 contains two phenanthrenes connected at the 9th position, and there is an angle between them and the benzene ring, reducing the conjugation degree, so the refractive index is lower. In Comparative Examples CP-5 and CP-6, they contain two benzoxazole groups, which increases the polarizability, but only increases the refractive index of blue light. Since Δn, the refractive index of red light is not increased, and the effect of comprehensively improving white light is not satisfied.

[0100] The test results of the light absorption coefficients of the compounds in the examples of the present application and the materials of the comparative examples are shown in Table 3.

[0101] Table 3 Light Absorption Coefficient and Tg of the Compounds in the Examples of the Present Application and the Materials of the Comparative Examples

[0102]

[0103]

[0104] The covering layer material of the embodiments of the present application has an absorption coefficient higher than that of the material of the comparative example at 400 nm. The compound of the embodiments of the present application is beneficial to protecting the OLED device from being damaged by ultraviolet light in the external environment, absorbing the external ultraviolet light, and preventing the device from aging. At the same time, the absorption coefficient at 450 nm is almost 0, which is beneficial to avoiding affecting the light emitted by the OLED device itself. Moreover, the covering layer material of the present application has a higher glass transition temperature than the material of the comparative example, further indicating that the material structure of the covering layer of the present application is stable.

[0105] In a second aspect, an embodiment of the present application provides a light-emitting device, as Figure 1 shown, including a substrate 1, a first electrode 2, a light-emitting layer 20, a second electrode 10, and a covering layer 30 which are sequentially stacked;

[0106] Among them, the material of the covering layer 30 is the covering layer material of the first aspect; the first electrode 2 is an anode, and the anode can be a transparent conductive polymer, such as but not limited to ITO or IZO, or can also be a composite electrode formed by ITO / Ag / ITO, Ag / IZO, CNT / ITO, CNT / IZO, etc.; the second electrode 10 can be a silver-magnesium composite electrode or an Al electrode. The substrate 1 can be a transparent rigid or flexible material, such as glass, polyimide, etc., and can realize rigid substrate display and flexible display, such as ITO.

[0107] In the light-emitting device of the present application, the structural formula of the material of the covering layer includes an arylamine structure and a phenanthrene ring, where the phenanthrene ring is a pure aryl group without heteroatoms. While increasing the polarizability of the covering layer material and improving the refractive index, the difference between the blue light refractive index and the red light refractive index can be reduced, which is beneficial to improving the white light efficiency; and, Ar is a fused structure containing heteroatoms, and the fused structure can increase the conjugation of the structural formula, which is beneficial to further improving the refractive index, ensuring that the display panel has a good light-emitting effect, while being beneficial to improving the white light efficiency, so as to improve the display effect of the display panel, and further improve the product yield and product competitiveness.

[0108] In a third aspect, an embodiment of the present application provides a light-emitting device, as Figure 1 shown, including a substrate 1, a first electrode 2, a light-emitting layer 20, a second electrode 10, and a covering layer 30;

[0109] The material of the light-emitting layer 20 includes two host materials, and at least one hydrogen atom in the structural formula of at least one host material is replaced by deuterium;

[0110] Or, at least one host material contains heteroatoms in its structural formula;

[0111] Or, at least one hydrogen atom in the structural formula of at least one host material is replaced by deuterium and the structural formula contains heteroatoms.

[0112] The material of the cover layer 30 is the cover layer material of the first aspect.

[0113] It can be understood that the material of the light-emitting layer generally includes a host material and a guest material. In the embodiments of the present application, the light-emitting layer includes two host materials. One may be that at least one hydrogen atom in the structural formula of a host material is replaced by deuterium, and the other material is a conventional organic light-emitting material; or both may be that at least one hydrogen atom in the structural formula of the two host materials is replaced by deuterium; or, one may be that the structural formula of a host material contains a heteroatom, and the other host material is a conventional organic light-emitting material; or both may be that the structural formula of the two host materials contains a heteroatom; or one may be that at least one hydrogen atom in the structural formula of a host material is replaced by deuterium and contains a heteroatom, and the other is a conventional organic light-emitting material, or both may be that at least one hydrogen atom in the structural formula of the two host materials is replaced by deuterium and contains a heteroatom.

[0114] Among them, the heteroatom can be but is not limited to oxygen, nitrogen or sulfur.

[0115] It can also be understood that the light-emitting layer can be a blue light-emitting layer, a red light-emitting layer or a green light-emitting layer, which is specifically determined according to the actual product requirements.

[0116] In the embodiments of the present application, the light-emitting layer material includes two host materials. Among them, at least one hydrogen atom in the host material is replaced by deuterium, which is beneficial to improving the lifespan of the light-emitting material. The structural formula of the host material contains an atom, which can be used to reduce the driving voltage, and the cover layer adopts the above-mentioned cover layer material, which is beneficial to reducing the driving voltage and prolonging the service life of the light-emitting device while improving the light extraction efficiency of the light-emitting device.

[0117] In some embodiments, at least one hydrogen atom in the structural formula of one host material is replaced by deuterium, and the structure of the other host material contains a heteroatom;

[0118] Or, at least one hydrogen atom in the structural formula of one host material is replaced by deuterium, and at least one hydrogen atom in the structural formula of the other host material is replaced by deuterium and the structural formula contains a heteroatom.

[0119] In a preferred embodiment, at least one hydrogen atom in the structural formula of one host material is replaced by deuterium, and the structure of the other host material contains a heteroatom O.

[0120] As an implementable manner, such as Figure 2As shown, the light-emitting device further includes, on the side of the second electrode 10 facing away from the covering layer 30, an electron injection layer (EIL) 9, an electron transport layer (ETL) 8, and a hole blocking layer (HBL) 7 stacked in sequence along the direction close to the substrate 1. The light-emitting layer 20 is disposed on the side of the hole blocking layer 7 close to the substrate 1. On the side of the light-emitting layer 20 away from the hole blocking layer, an electron blocking layer (EBL) 5, a hole transport layer (HTL) 4, and a hole injection layer (HIL) 3 are stacked in sequence along the direction close to the substrate 1. The hole injection layer 3 is located on the side of the first electrode 2 away from the substrate 1.

[0121] Among them, the hole injection layer 3 can be an inorganic oxide, such as oxides of metals such as molybdenum, titanium, vanadium, rhenium, ruthenium, chromium, zirconium, hafnium, tantalum, silver, tungsten, or manganese, or can also be a dopant with a strong electron-withdrawing system, such as F4TCNQ, HAT-CN, etc., or can also perform P-type doping on the hole transport layer 4. The thickness of the hole injection layer 3 can be 5 nm to 30 nm.

[0122] The material of the hole transport layer 4 has good hole transport characteristics and can also be an arylamine or carbazole material, such as NPB, TPD, BAFLP, DFLDPBi, etc. The thickness of the hole transport layer 4 can be 30 nm to 150 nm.

[0123] The electron blocking layer 5, that is, the light-emitting auxiliary layer, has hole transport characteristics and can be a red light-emitting auxiliary layer, a green light-emitting auxiliary layer, or a blue light-emitting auxiliary layer. The thickness of the electron blocking layer 5 can be 5 nm to 50 nm.

[0124] The light-emitting layer 20 can be a phosphorescent host and a red phosphorescent dopant, a phosphorescent host and a green phosphorescent dopant, or a fluorescent host and a fluorescent dopant. The light-emitting layer 20 can contain two or more mixed materials. Among them, the blue light-emitting layer host material can be selected from two of anthracene derivatives such as ADN, MADN, etc., and the guest material can be pyrene derivatives, fluorene derivatives, perylene derivatives, styrylamine derivatives, metal complexes, etc., such as TBPe, BDAVBi, DPAVBi, FIrpic, etc.; the green light-emitting layer host material can be selected from coumarin dyes, quinacridone derivatives, polycyclic aromatic hydrocarbons, diaminoanthracene derivatives, carbazole derivatives, such as DMQA, BA-NPB, Alq3, CBP, etc., and the guest material can be a metal complex, such as Ir(ppy)3, Ir(ppy)2(acac), etc.; the red light-emitting host material can be selected from DCM series materials, such as DCM, DCJTB, DCJTI, etc., and the guest material can be a metal complex, such as Ir(piq)2(acac), PtOEP, Ir(btp)2(acac), etc. The thickness of the light-emitting layer 20 can be 20 nm to 100 nm.

[0125] In a preferred embodiment, the thickness of the hole blocking layer 7 can be 5 nm to 100 nm, and the thickness of the electron transport layer 8 can be 20 nm to 100 nm. The electron transport layer 8 includes aromatic heterocyclic compounds, such as imidazole derivatives like benzimidazole derivatives, imidazopyridine derivatives, benzimidazole phenanthridine derivatives, etc., and oxazine derivatives like pyrimidine derivatives, triazine derivatives, etc., and compounds containing a nitrogen-containing six-membered ring structure like quinoline derivatives, isoquinoline derivatives, phenanthroline derivatives, etc., and can also include compounds having a phosphine oxide-based substituent on the heterocycle, such as: OXD-7, TAZ, p-EtTAZ), BPhen, BCP.

[0126] The thickness of the electron injection layer 9 can be 1 nm to 10 nm, and the material of the electron injection layer 9 includes alkali metals or metals, such as LiF, Yb, Mg, Ca, or their compounds, etc.

[0127] Taking Figure 1 and 2 the organic electroluminescent device shown as an example, the structure of the light-emitting device in the embodiment of the present application is: substrate 1 / first electrode 2 (ITO) / hole injection layer 3 (10 nm) / hole transport layer 4 (110 nm) / electron blocking layer 5 (5 nm) / light-emitting layer 20 (20 nm) / hole blocking layer 7 (5 nm) / electron transport layer 8 (30 nm) / electron injection layer 9 (1 nm) / second electrode 10 (13 nm) / cover layer (65 nm).

[0128] Exemplarily, for the structural formula shown below, the material of the hole injection layer 3 is HAT-CN, the material of the electron blocking layer 5 is TCTA, the material of the hole blocking layer 7 is TPBi, the blue light host material of the light-emitting layer 20 is BH, the guest material is BD, the material of the hole transport layer 4 is NPB, the material of the electron transport layer is Bphen, the material of the electron injection layer is ytterbium metal (Yb), and the cover layer uses the cover layer material of the embodiment of the present application.

[0129]

[0130]

[0131] Another exemplarily, the preparation process of the light-emitting device in the embodiment of the present application is specifically described:

[0132] (1) After ultrasonic treatment of the substrate 1 (glass plate) provided with the first electrode 2 (ITO) in a cleaning agent, it is rinsed in deionized water, and then ultrasonically degreased in an acetone-ethanol mixed solvent, and baked in a clean environment until all moisture is completely removed;

[0133] (2) Place the glass plate provided with ITO in a vacuum chamber, evacuate to 1×10 -5~1×10 -6 , on the side of the ITO away from the glass plate, the material HAT-CN of the hole injection layer 3 is vacuum-evaporated to form the hole injection layer 3;

[0134] (3) On the side of the hole injection layer 3 away from the ITO, the material NPB of the hole transport layer 4 is evaporated to form the hole transport layer 4;

[0135] (4) On the side of the hole transport layer away from the hole injection layer, the material TCTA of the electron blocking layer is vacuum-evaporated to form the electron blocking layer 5;

[0136] (5) On the side of the electron blocking layer 5 away from the hole transport layer 4, a light-emitting material is vacuum-evaporated to form the light-emitting layer 20. The light-emitting material includes a host material and a guest material. By using the method of co-evaporation of multiple sources, the weight ratio of the host material to the guest material is 99:1

[0137] (6) On the side of the light-emitting layer 20 away from the electron blocking layer 5, the material TPBi of the hole blocking layer is vacuum-evaporated to form the hole blocking layer 7.

[0138] (7) On the side of the hole blocking layer 7 away from the light-emitting layer 20, an electron transport material is vacuum-evaporated to form the electron transport layer 8.

[0139] (8) On the side of the electron transport layer 8 away from the hole blocking layer 7, an inorganic substance LiF with a thickness of 1 nm is vacuum-evaporated as the electron injection material to form the electron injection layer 9.

[0140] (9) On the side of the electron injection layer 9 away from the electron transport layer 8, an Al layer is evaporated as the cathode;

[0141] (10) A covering layer material is formed on the side of the cathode layer away from the electron injection layer 9.

[0142] The following uses specific embodiments to illustrate the light-emitting device provided by the embodiments of the present application:

[0143] Embodiment 1

[0144] The device D1 is prepared by using the above-mentioned method for preparing a light-emitting device. Among them, the light-emitting layer uses the material BH-1, and the covering layer uses the material CP-1 of the comparative example.

[0145] Embodiment 2

[0146] The device D2 is prepared by using the above-mentioned method for preparing a light-emitting device. Among them, the light-emitting layer uses the material BH-2, and the covering layer uses the material CP-1 of the comparative example.

[0147] Embodiment 3

[0148] Device D3 was fabricated using the above-mentioned method for fabricating light-emitting devices. Among them, the light-emitting layer used a BH-1:BH-2 hybrid material (ratio 5:5), and the capping layer used the material of Comparative Example CP-1.

[0149] Example 4

[0150] Device D4 (including devices of three colors RGB) was fabricated using the above-mentioned method for fabricating light-emitting devices. Among them, the red light-emitting layer used the above-mentioned RH-N, RH-P, and RH-D, the green light-emitting layer used the above-mentioned RH-N, RH-P, and RH-D, the blue light-emitting layer used BH-3, and the capping layer used the material of Comparative Example CP-1.

[0151] Example 5

[0152] Device D5 (including devices of three colors RGB) was fabricated using the above-mentioned method for fabricating light-emitting devices. Among them, the red light-emitting layer used the above-mentioned RH-N, RH-P, and RH-D, the green light-emitting layer used the above-mentioned RH-N, RH-P, and RH-D, the blue light-emitting layer used BH-4, and the capping layer used the material of Comparative Example CP-1.

[0153] Example 6

[0154] Device D6 was fabricated using the above-mentioned method for fabricating light-emitting devices. Among them, the blue light-emitting layer used a BH-1:BH-3 hybrid material (ratio 5:5), and the capping layer used the material of Comparative Example CP-1.

[0155] Example 7

[0156] Device D7 was fabricated using the above-mentioned method for fabricating light-emitting devices. Among them, the blue light-emitting layer used a BH-1:BH-4 hybrid material (ratio 5:5), and the capping layer used the material of Comparative Example CP-1.

[0157] Example 8

[0158] Device D8 was fabricated using the above-mentioned method for fabricating light-emitting devices. Among them, the blue light-emitting layer used a BH-1:BH-2 hybrid material (ratio 5:5), and the capping layer used Compound 1 material.

[0159] Example 9

[0160] Device D9 was fabricated using the above-mentioned method for fabricating light-emitting devices. Among them, the blue light-emitting layer used a BH-1:BH-2 hybrid material (ratio 5:5), and the capping layer used Compound 2 material.

[0161] Example 10

[0162] Device D10 is fabricated using the above-mentioned light-emitting device fabrication method. Among them, the blue light-emitting layer uses a BH-1:BH-2 mixed material (ratio 5:5), and the capping layer uses Compound 5 material.

[0163] Among them, BH-1, BH-2, BH-3, and BH-4 use the following materials:

[0164]

[0165] The test results of the voltage, efficiency, and lifetime of the light-emitting devices in the above embodiments are shown in Table 4:

[0166] Table 4 Test results of the light-emitting devices in Examples 1-10

[0167]

[0168]

[0169] From the test results in Table 4, it can be obtained that the lifetime of the deuterated light-emitting layer material is significantly improved, and the device voltage is improved by using BH containing heteroatom O; due to the current product's demand for low voltage and long lifetime, the method of mixing two host materials can combine the advantages of both; further, in device D3, one BH in the light-emitting layer material contains O and the other BH does not contain heteroatoms, and both are deuterated simultaneously, and a blue light device with both voltage and lifetime characteristics can be obtained.

[0170] Devices D8-D10 use the capping layer material of this application and combine the structure of two host materials mixed. It can be seen that the efficiency of the light-emitting device is significantly improved, the voltage is reduced to a certain extent, and the characteristic of long lifetime is maintained. Therefore, a blue light device with low voltage, long lifetime, and high efficiency is obtained.

[0171] The process of fabricating the white light device is the same as that of the above-mentioned light-emitting device, and the device structures are as follows:

[0172] Blue light device:

[0173] HIL(10nm) / HTL(110nm) / EBL(5nm) / BH-1:BH-2:BD(20nm, 5:5, 1%) / HBL(5nm) / ETL:LIQ(30nm, 50%) / EIL(1nm) / Mg:Ag 13nm / CPL 65nm;

[0174] Green light device: HIL(10nm) / HTL(110nm) / EBL(35nm) / GH:GD(35nm, 5:5, 8%) / HBL(5nm) / ETL:LIQ(30nm, 50%) / EIL(1nm) / Mg:Ag 13nm / CPL 65nm;

[0175] Red light device: HIL(10nm) / HTL(110nm) / EBL(75nm) / RH:RD(45nm, 5:5, 2%) / HBL(5nm) / ETL:LIQ(30nm, 50%) / EIL(1nm) / Mg:Ag 13nm / CPL 65nm.

[0176] Among them,

[0177] Device W1 (including devices of three colors RGB): CPL uses Compound 1 material.

[0178] Device W2 (including devices of three colors RGB): CPL uses Compound 2 material, and others remain unchanged.

[0179] Device W3 (including devices of three colors RGB): CPL uses Compound 3 material, and others remain unchanged.

[0180] Device W4 (including devices of three colors RGB): The CPL layer uses Compound 4 material, and others remain unchanged.

[0181] Fabrication of Device W5 (including devices of three colors RGB): CPL uses Compound 5 material, and others remain unchanged.

[0182] Fabrication of Device W16 (including devices of three colors RGB): CPL uses Compound 16 material, and others remain unchanged.

[0183] Device W17 (including devices of three colors RGB): CPL uses Compound 17 material, and others remain unchanged.

[0184] Device W40 (including devices of three colors RGB): CPL uses Compound 40 material, and others remain unchanged.

[0185] Device W-R1 (including devices of three colors RGB): CPL uses Comparative Example CP-1 material, and others remain unchanged.

[0186] Device W-R3 (including devices of three colors RGB): CPL uses Comparative Example CP-3 material, and others remain unchanged.

[0187] Device W-R5 (including devices of three colors RGB): CPL uses Comparative Example CP-5 material, and others remain unchanged.

[0188] The above white light devices are tested, and the test results are as shown in Figure 5;

[0189] Table 5 Test Results of White Light Devices

[0190]

[0191] It can be obtained from the results in Table 5 that: compared with Comparative Example CP-1, the white light efficiency of the compounds in the examples of the present application is improved, and at the same time, the white light L-decay (30°) is controlled within 30%.

[0192] In a fourth aspect, the present invention provides a display panel, including the light-emitting device of the second aspect. It can be understood that this display panel has all the characteristics and advantages of the light-emitting device of the second aspect. Here, it will not be elaborated.

[0193] In a fifth aspect, the present invention provides a display device, including the display panel of the fourth aspect. It can be understood that this display device has all the characteristics and advantages of the display panel of the fourth aspect. Here, it will not be elaborated. In short, this display device has high quality and yield, good display effect, high light extraction efficiency, and high white light efficiency.

[0194] The display device is a product with an image display function. For example, the display device can be: a monitor, a television, a billboard, a digital photo frame, a laser printer with a display function, a telephone, a mobile phone, a personal digital assistant (Personal Digital Assistant, PDA), a digital camera, a portable video camera, a viewfinder, a navigator, a vehicle, a large-area wall, a household appliance, an information query device (such as a business query device in departments such as e-government, banks, hospitals, and power), a monitor, etc. The display device can also be a microdisplay or a product containing a microdisplay. The product containing a microdisplay can be a smart watch, a smart bracelet, a head-mounted display, a stereoscopic display mirror, and an AR device (such as AR glasses), a VR device (such as VR glasses), etc. For example, the microdisplay can be a display with a display size ranging from about 0.2 inches to about 2.5 inches, but not limited thereto. It can be understood that the microdisplay can also be a display with a smaller display size, such as a display size less than or equal to 0.2 inches.

[0195] It should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. in the foregoing is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the panel or component referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0196] The above description is only the preferred embodiment of the present application and the explanation of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the technical solutions formed by mutually replacing the above features with the technical features (but not limited to) having similar functions disclosed in the present application.

Claims

1. A covering material, characterized in that: The structural formula of the covering layer material is shown in the following structural formula I: Wherein, ring A and ring B are each a phenanthrene ring; L1, L2 and L3 are each independently selected from a single bond, a phenyl group, a biphenyl group or a naphthyl group; R1, R2 are each independently selected from hydrogen, deuterium, C1-C5 alkyl or C6-C20 aryl; Ar group is selected from one of the structural formula II to structural formula IX; Wherein, X is selected from O or S, and Y is selected from C or N.

2. The covering material according to claim 1, characterized in that: At least one of the phenanthrene rings in the ring A and the ring B is connected at the 2-position.

3. The covering material according to claim 2, characterized in that: One of the phenanthrene rings in the ring A and the ring B is connected at the 2-position, and the other phenanthrene ring is connected at the 9-position.

4. The covering material according to claim 1, characterized in that: In the structural formula I, except for the aromatic amine N atom, the number of other heteroatoms is less than or equal to 2, and the heteroatoms include N, O or S.

5. The covering material according to claim 4, characterized in that: The number of heteroatoms in the Ar group is 0 or 1.

6. The covering material according to claim 1, characterized in that The structural formula of the covering material is one of the following:

7. The cover material according to any one of claims 1 to 6, wherein the refractive index difference between the cover material in blue light and red light is Δn, Δn≤0.48*n(@460nm)-0.868; wherein, n(@460nm) is the refractive index of the cover layer material at a wavelength of 460nm.

8. A light emitting device, characterized in that: It includes an anode, a light-emitting layer, a cathode and a covering layer which are stacked; The material of the covering layer is the covering layer material according to any one of claims 1 to 7.

9. The light emitting device according to claim 8, characterized in that: The material of the light-emitting layer includes two main materials, and at least one hydrogen atom in the structural formula of at least one of the main materials is replaced by deuterium; Alternatively, at least one of the host materials has a structural formula containing a heteroatom; Alternatively, at least one hydrogen atom in the structural formula of at least one of the host materials is substituted with deuterium and the structural formula contains a heteroatom.

10. The light emitting device according to claim 9, characterized in that: At least one hydrogen atom in the structural formula of one of the host materials is replaced by deuterium, and the structure of the other host material contains heteroatoms; Alternatively, at least one hydrogen atom in the structural formula of one of the host materials is substituted by deuterium, and at least one hydrogen atom in the structural formula of the other host material is substituted by deuterium and contains a heteroatom.

11. The light emitting device according to claim 10, characterized in that: In the structural formula of one of the host materials, at least one hydrogen atom is replaced by deuterium, and in the structure of the other host material, a heteroatom O is included.

12. A display panel, characterized in that: A light emitting device comprising any one of claims 8 to 11.

13. A display device, characterized in that: Includes the display panel as claimed in claim 12.

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