Luminescent material and preparation method thereof, display panel and display device

Abstract

The present invention provides a luminescent material and a preparation method thereof, a display panel, and a display device. The luminescent material includes a compound of the structural formula (1), wherein X is a halogen element, and R1 and R2 are each independently H, a substituted or unsubstituted alkyl group of C1 to C18, a substituted or unsubstituted heteroalkyl group of C2 to C18, a substituted or unsubstituted alkenyl group of C3 to C18, a substituted or unsubstituted heteroalkenyl group of C3 to C18, a substituted or unsubstituted alkynyl group of C3 to C18, a substituted or unsubstituted heteroalkynyl group of C3 to C18, a substituted or unsubstituted aryl group of C6 to C18, or a substituted or unsubstituted heteroaryl group of C6 to C18. Thus, the heavy atom effect of the halogen element and the presence of the unsaturated double bond C=O can promote spin-orbit coupling, thereby promoting the luminescence of the thermally activated delayed fluorescent material; the spirocyclic structure in the middle of the material structure can undergo a switch ring structure transformation under energy stimulation, changing the emission wavelength, thereby achieving a photochromic effect.

Description

Technical Field

[0001] The present invention relates to the field of materials, and in particular to a luminescent material and a preparation method thereof, a display panel and a display device. Background Art

[0002] Photochromic materials, which change color when stimulated by a light source, have enormous potential for applications in optical information storage, self-developing photographic films, and holography due to their bistability. This bistability means that the material is stable before and after exposure to light. In optical information storage, information can be stored using one type of light and retrieved using another. In development applications, the material can be developed using one type of light and erased using another.

[0003] Thermally activated delayed fluorescence (TADF) materials are the third generation of organic light-emitting materials developed after organic fluorescent materials and organic phosphorescent materials. They have great application prospects in many fields such as organic light-emitting diodes, anti-counterfeiting encryption, and analytical detection. Compared with traditional fluorescent materials, TADF materials can utilize triplet excitons through the reverse intersystem crossing (RISC) process from T1 to the lowest singlet excited state (S1), that is, they can simultaneously utilize the singlet excited state and the triplet excited state, and thus have a theoretical internal quantum efficiency of 100%. Compared with traditional phosphorescent materials, TADF materials are pure organic materials, do not contain heavy metals, are lower in cost, and are more environmentally friendly. Therefore, the development of new TADF materials is of great significance.

[0004] However, no material has been found to have both photochromic properties and thermally activated delayed fluorescence emission properties. Summary of the Invention

[0005] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0006] In one aspect of the present invention, the present invention provides a luminescent material. According to an embodiment of the present invention, the luminescent material includes a compound having a structural formula (1),

[0007]

[0008] Wherein, X is a halogen element, and R1 and R2 are each independently H, a C1-C18 substituted or unsubstituted alkyl group, a C2-C18 substituted or unsubstituted heteroalkyl group, a C3-C18 substituted or unsubstituted alkenyl group, a C3-C18 substituted or unsubstituted heteroalkenyl group, a C3-C18 substituted or unsubstituted alkynyl group, a C3-C18 substituted or unsubstituted heteroalkynyl group, a C6-C18 substituted or unsubstituted aryl group, or a C6-C18 substituted or unsubstituted heteroaryl group. Thus, the heavy atom effect of the halogen element and the presence of the unsaturated double bond C=O can promote spin-orbit coupling, thereby promoting the luminescence of the thermally activated delayed fluorescent material. The spirocyclic structure in the middle of the material structure can undergo a switching ring structure transformation under energy stimulation, changing the emission wavelength and achieving a photochromic effect.

[0009] According to an embodiment of the present invention, in formula (1), R1 is a substituted alkyl group, the substituent in R1 is a hydroxyl group; and R2 is an unsubstituted alkyl group.

[0010] According to an embodiment of the present invention, the luminescent material includes a compound having a structural formula (1-1),

[0011] The luminescent material has both the thermally activated delayed fluorescence emission property of emitting red fluorescence under visible light excitation and the photochromic property of changing color after irradiation with ultraviolet light; the material can be used in the luminescent layer of an organic light-emitting device to adjust the luminescent properties.

[0012] According to an embodiment of the present invention, the luminescent material includes a compound having a structural formula (1-2),

[0013] The luminescent material has the properties of thermally activated delayed fluorescence emission, which emits red fluorescence under visible light excitation, and photochromic properties, which can change color after irradiation with ultraviolet light. The material can be used in the luminescent layer of an organic light-emitting device to adjust the luminescent properties.

[0014] In another aspect of the present invention, a method for preparing a luminescent material is provided. According to an embodiment of the present invention, the method for preparing a luminescent material comprises: a compound having a structural formula of formula (3) and a compound having a structural formula of formula (4) undergo a first reaction to generate a compound having a structural formula of formula (5),

[0015]

[0016] The compound of formula (6) and the compound of formula (7) undergo a second reaction to generate a compound of formula (8).

[0017]

[0018] The compound of formula (5) and the compound of formula (8) undergo a third reaction to generate a compound of formula (1).

[0019] Wherein, X is a halogen element, and R1 and R2 are each independently a C1-C18 substituted or unsubstituted alkyl, a C2-C18 substituted or unsubstituted heteroalkyl, a C3-C18 substituted or unsubstituted alkenyl, a C3-C18 substituted or unsubstituted heteroalkenyl, a C3-C18 substituted or unsubstituted alkynyl, a C3-C18 substituted or unsubstituted heteroalkynyl, a C6-C18 substituted or unsubstituted aryl, or a C6-C18 substituted or unsubstituted heteroaryl.

[0020] Therefore, the luminescent material prepared by this method contains both halogen elements and spiro structures. The heavy atom effect of the halogen elements and the presence of the unsaturated double bond C=O can promote spin-orbit coupling, thereby promoting the luminescence of the thermally activated delayed fluorescent material; the spiro structure in the middle of the material structure can undergo a switching ring structure transformation under energy stimulation, changing the emission wavelength and playing a photochromic role.

[0021] According to an embodiment of the present invention, the method for preparing a luminescent material satisfies at least one of the following conditions: the solvent for the first reaction includes ethanol; the temperature for the first reaction is 60°C to 80°C; the solvent for the second reaction includes N,N-dimethylformamide; the temperature for the second reaction is 160°C to 180°C; the catalyst for the second reaction includes at least one of 4-dimethylaminopyridine and 1-ethyl-(3-dimethylaminopropyl)carbodiimide; in the second reaction, the ratio of the mass of the catalyst to the mass of the compound having the structural formula (6) is 1:100 to 1:20; the solvent for the third reaction includes N,N-dimethylformamide; and the temperature for the third reaction is 160°C to 180°C. Carrying out the reaction under the above conditions is more conducive to improving the yield of the luminescent material.

[0022] According to an embodiment of the present invention, a compound having a structural formula of formula (3-1) and a compound having a structural formula of formula (4-1) undergo a first reaction to generate a compound having a structural formula of formula (5-1).

[0023]

[0024] The compound of formula (6) undergoes a second reaction with ethanol to generate a compound of formula (8-1).

[0025]

[0026] The compound of formula (5-1) and the compound of formula (8-1) undergo a third reaction to generate a compound of formula (1-1).

[0027]

[0028] According to an embodiment of the present invention, a compound having a structural formula of formula (3-2) and a compound having a structural formula of formula (4-1) undergo a first reaction to generate a compound having a structural formula of formula (5-2).

[0029]

[0030] The compound of formula (6) undergoes a second reaction with ethanol to generate a compound of formula (8-1).

[0031]

[0032] The compound of formula (5-2) undergoes a third reaction with the compound of formula (8-1) to generate a compound of formula (1-2).

[0033]

[0034] According to an embodiment of the present invention, during the reaction process, substances in the reaction system are tested by thin-layer chromatography to determine whether the raw materials have reacted completely. By testing the substances in the reaction system by thin-layer chromatography, if no chromatogram of a certain raw material is detected, the reaction can be determined to be complete, and the next reaction can be carried out. Furthermore, the utilization rate of the raw materials can be further improved.

[0035] In another aspect, the present invention provides a display panel. According to an embodiment of the present invention, the display panel includes a light-emitting unit, wherein the light-emitting unit includes a light-emitting layer, and the material of the light-emitting layer includes the light-emitting material described above or a light-emitting material prepared using the method described above. Thus, the display panel has all the features and advantages of the light-emitting material described above or a light-emitting material prepared using the method described above, and no further description is given here. In general, the display panel has good light-emitting performance and display effects.

[0036] According to an embodiment of the present invention, the material of the light-emitting layer further includes a main light-emitting material, and the main light-emitting material includes at least one of 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulonitrile-9-enyl)-4H-pyran, bis(1-phenylisoquinoline)(acetylacetonate)iridium(III), bis(2-(2'-benzothienyl)pyridine-N,C3')(acetylacetonate)iridium, and octaethylporphyrin platinum. Therefore, by combining the main light-emitting material with the aforementioned light-emitting materials, the light-emitting performance of the display panel can be further improved.

[0037] According to an embodiment of the present invention, in the light-emitting layer, the mass ratio of the light-emitting material to the main light-emitting material is 1:100 to 1:20. Thus, the light-emitting material and the main light-emitting material have a suitable mass ratio, and the light-emitting material can effectively adjust the light-emitting performance, thereby further improving the light-emitting performance of the display panel.

[0038] In yet another aspect, the present invention provides a display device. According to an embodiment of the present invention, the display device includes the display panel described above. This display device possesses all the features and advantages of the display panel described above, and will not be further elaborated here. In general, this display device provides excellent display performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A flow chart of a method for preparing a luminescent material according to one embodiment of the present invention is shown;

[0040] Figure 2 shows a hydrogen nuclear magnetic resonance spectrum of a luminescent material according to an embodiment of the present invention;

[0041] Figure 3 shows the fluorescence emission / excitation spectrum and delayed fluorescence emission / excitation spectrum of the luminescent material of one embodiment of the present invention;

[0042] Figure 4 A picture showing a luminescent material according to one embodiment of the present invention;

[0043] Figure 5 shows a schematic structural diagram of a display panel according to an embodiment of the present invention;

[0044] Figure 6 FIG. 4 shows a structural diagram of a display panel according to another embodiment of the present invention.

[0045] Description of reference numerals:

[0046] 100: substrate; 200: pixel defining layer; 300: light-emitting unit; 310: anode; 320: light-emitting layer; 330: cathode; 340: hole injection layer; 350: hole transport layer; 360: electron blocking layer; 370: hole blocking layer; 380: electron transport layer; 390: electron injection layer. DETAILED DESCRIPTION

[0047] The following embodiments of the present invention are described in detail. The embodiments described below are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in the art or in the product specifications shall be followed.

[0048] In one aspect of the present invention, a luminescent material is provided. According to an embodiment of the present invention, the luminescent material may include a compound having a structural formula of formula (1).

[0049]

[0050] Wherein, X may be a halogen element, for example, X may be fluorine (F), chlorine (Cl), bromine (Br), iodine (I) or astatine (At), and R1 and R2 may each independently be H, a C1-C18 substituted or unsubstituted alkyl group, a C2-C18 substituted or unsubstituted heteroalkyl group, a C3-C18 substituted or unsubstituted alkenyl group, a C3-C18 substituted or unsubstituted heteroalkenyl group, a C3-C18 substituted or unsubstituted alkynyl group, a C3-C18 substituted or unsubstituted heteroalkynyl group, a C6-C18 substituted or unsubstituted aryl group, or a C6-C18 substituted or unsubstituted heteroaryl group. The heavy atom effect of halogen elements and the presence of unsaturated double bonds containing heteroatoms can promote spin-orbit coupling, thereby promoting the luminescence of thermally activated delayed fluorescent materials; the spirocyclic structure in the middle of the material structure (the ring where the nitrogen atom and the ring where the oxygen atom are located in the middle of the structure share a carbon atom) can undergo a switching ring structure transformation under energy stimulation, changing the emission wavelength and playing a photochromic role; the material has a special spatially twisted structure and a high lateral resistance. Adding this material to the device can, at least to a certain extent, reduce lateral leakage and improve crosstalk between adjacent light-emitting units.

[0051] In the present invention, heteroalkyl, heteroalkenyl, heteroalkynyl, and heteroaryl refer to groups formed by replacing carbon atoms in alkyl, alkenyl, alkynyl, and aryl groups with heteroatoms such as O, N, and S. "Substituted or unsubstituted" refers to whether the H atoms in the alkyl, heteroalkyl, alkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, and heteroaryl groups are substituted or unsubstituted. When H atoms are substituted, the substituents may be hydroxyl, amino, or halogen atoms. "C1-C18," "C2-C18," "C3-C18," and the like refer to the number of carbon atoms in R1 or R2.

[0052] According to an embodiment of the present invention, in formula (1), R1 may be a substituted alkyl group, the substituent in R1 may be a hydroxyl group; and R2 may be an unsubstituted alkyl group. According to some embodiments of the present invention, R1 may be an alkyl group having 2 carbon atoms, the substituent in R1 may be a hydroxyl group. According to some embodiments of the present invention, R2 may be an unsubstituted alkyl group having 2 carbon atoms.

[0053] According to some specific embodiments of the present invention, the luminescent material may include a compound having a structural formula (1-1),

[0054]

[0055] According to some other specific embodiments of the present invention, the luminescent material may include a compound having a structural formula (1-2):

[0056]

[0057] In the compound with the structural formula (1-1) and the compound with the structural formula (1-2), the halogen elements bromine or chlorine have a heavy atom effect, which can promote spin-orbit coupling. The presence of the C=O unsaturated double bond can also promote spin-orbit coupling, thereby promoting the luminescence of the TADF material; the spirocyclic structure in the middle of the structure can undergo a ring-opening or ring-closing reaction under energy stimulation, thereby changing the structure of the material and thus changing the emission wavelength, thereby playing a photochromic role; the spatially twisted structure of the material has a high lateral resistance. Using this material in a light-emitting device can reduce lateral leakage to a certain extent, improve crosstalk between adjacent light-emitting units, and help improve the display effect of the display device.

[0058] In another aspect of the present invention, the present invention provides a method for preparing a luminescent material. Figure 1 , the method for preparing the luminescent material may include the following steps:

[0059] S100: The compound with the structural formula (3) and the compound with the structural formula (4) undergo a first reaction to generate a compound with the structural formula (5).

[0060]

[0061] In formula (3), X may be a halogen element, for example, X may be fluorine, chlorine, bromine, iodine or astatine.

[0062] In formula (4), R1 can be a C1-C18 substituted or unsubstituted alkyl group, a C2-C18 substituted or unsubstituted heteroalkyl group, a C3-C18 substituted or unsubstituted alkenyl group, a C3-C18 substituted or unsubstituted heteroalkenyl group, a C3-C18 substituted or unsubstituted alkynyl group, a C3-C18 substituted or unsubstituted heteroalkynyl group, a C6-C18 substituted or unsubstituted aryl group, or a C6-C18 substituted or unsubstituted heteroaryl group.

[0063] According to some embodiments of the present invention, the solvent for the first reaction may include ethanol. That is, the compound with the structural formula (3) and the compound with the structural formula (4) may be dissolved in a first solvent to carry out the first reaction. The first solvent may include ethanol. In some specific embodiments of the present invention, the first solvent may be ethanol. The above-mentioned reaction raw materials have good solubility in ethanol, which can promote the uniformity of the reaction.

[0064] According to some embodiments of the present invention, the temperature of the first reaction can be 60°C to 80°C. For example, the temperature of the first reaction can be 60°C, 62°C, 65°C, 67°C, 70°C, 73°C, 75°C, 78°C, 80°C, etc. The temperature of the first reaction is within the above range, which is conducive to promoting the progress of the first reaction and improving the utilization rate of the reaction raw materials.

[0065] According to some embodiments of the present invention, the solvent of the first reaction is ethanol, and the temperature of the first reaction is 60°C to 80°C. Therefore, it is not only beneficial to the progress of the first reaction, but also allows the ethanol to evaporate and reflux continuously, so that the amount of solvent in the reaction system is within an appropriate range.

[0066] According to some embodiments of the present invention, during the first reaction, the reaction system may be stirred. For example, a magnetic stirrer may be added to the reaction system to control the stirring of the magnetic stirrer to promote rapid reaction. The present invention does not specifically limit the stirring speed, and those skilled in the art may configure and adjust the stirring speed based on actual conditions.

[0067] S200: The compound with the structural formula (6) and the compound with the structural formula (7) undergo a second reaction to generate a compound with the structural formula (8).

[0068]

[0069] In formula (7), R2 can be a C1-C18 substituted or unsubstituted alkyl group, a C2-C18 substituted or unsubstituted heteroalkyl group, a C3-C18 substituted or unsubstituted alkenyl group, a C3-C18 substituted or unsubstituted heteroalkenyl group, a C3-C18 substituted or unsubstituted alkynyl group, a C3-C18 substituted or unsubstituted heteroalkynyl group, a C6-C18 substituted or unsubstituted aryl group, or a C6-C18 substituted or unsubstituted heteroaryl group.

[0070] According to some embodiments of the present invention, the solvent of the second reaction may include N,N-dimethylformamide (DMF). According to some specific embodiments of the present invention, the solvent of the second reaction may be DMF. The reaction raw materials of the second reaction all have good solubility in DMF, and the reaction raw materials are dissolved in DMF to facilitate regulating the concentration of the raw materials.

[0071] According to some embodiments of the present invention, the temperature of the second reaction can be 160°C to 180°C. For example, the temperature of the second reaction can be 160°C, 163°C, 165°C, 167°C, 170°C, 172°C, 175°C, 178°C, 180°C, etc. Thus, the raw materials undergo the second reaction at this temperature, and the second reaction can proceed quickly, which is conducive to shortening the reaction time.

[0072] According to some embodiments of the present invention, the solvent for the second reaction can be DMF, and the temperature of the second reaction can be 160°C to 180°C. The above reaction temperature is not only conducive to the rapid progress of the reaction, but also conducive to the evaporation and reflux of the solvent DMF, thereby maintaining the amount of the solvent in the reaction system within an appropriate range.

[0073] According to some embodiments of the present invention, the catalyst for the second reaction may include at least one of 4-dimethylaminopyridine (DMAP) and 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC). The above catalysts can all play a good catalytic effect on the second reaction, promoting the rapid progress of the second reaction. According to some specific embodiments of the present invention, the catalyst for the second reaction may be DMAP. According to other specific embodiments of the present invention, the catalyst for the second reaction may be EDC. According to other specific embodiments of the present invention, the catalyst for the second reaction may be a mixture of DMAP and EDC.

[0074] According to some embodiments of the present invention, in the second reaction, the ratio of the mass of the catalyst to the mass of the compound having the structural formula (6) can be 1:100 to 1:20. For example, the ratio of the mass of the catalyst to the mass of the compound having the structural formula (6) can be 1:100, 1:80, 1:50, 1:30, 1:20, etc. Thus, the catalyst and the raw material have a suitable ratio, which is more conducive to the progress of the second reaction and does not cause waste of the catalyst.

[0075] S300: The compound with the structural formula (5) and the compound with the structural formula (8) undergo a third reaction to generate a compound with the structural formula (1).

[0076]

[0077] According to some embodiments of the present invention, the solvent of the third reaction may include N,N-dimethylformamide (DMF). The raw materials of the third reaction have higher solubility in this solvent, which is convenient for regulating the concentration of the raw materials. According to some embodiments of the present invention, the solvent of the third reaction may be DMF.

[0078] According to some embodiments of the present invention, the temperature of the third reaction can be 160°C to 180°C. For example, the temperature of the third reaction can be 160°C, 163°C, 165°C, 168°C, 170°C, 173°C, 175°C, 178°C, 180°C, etc. Carrying out the third reaction at a suitable temperature is conducive to the rapid progress of the third reaction.

[0079] According to some embodiments of the present invention, the solvent for the third reaction can be DMF, and the temperature of the third reaction can be 160°C to 180°C. This is not only conducive to the rapid progress of the third reaction, but also allows the solvent to be continuously evaporated and refluxed, maintaining the amount of solvent in the reaction system within an appropriate range.

[0080] According to some embodiments of the present invention, during the reaction process, the substances in the reaction system can be tested by thin layer chromatography to determine whether the raw materials have reacted completely. Of course, thin layer chromatography can be applied to the reaction of each step, that is, thin layer chromatography can be used to determine whether the raw materials of the first reaction, the second reaction and / or the third reaction have reacted completely. During the reaction process, a portion can be taken out from the reaction system and tested by thin layer chromatography. If the chromatogram of a certain reaction raw material is not detected in the test result, it can be determined that the raw material has reacted completely, the reaction is terminated, and subsequent reactions or the preparation of the materials can be carried out; conversely, if the chromatograms of all reaction raw materials in a certain reaction system are detected, the reaction can be continued.

[0081] The following describes a method for preparing a luminescent material in conjunction with some specific embodiments of the present invention. It will be appreciated by those skilled in the art that the following specific embodiments are intended for illustrative purposes only and are not intended to limit the scope of the present invention in any way. In addition, in the following examples, unless otherwise specified, the materials and equipment used are commercially available. If specific processing conditions and processing methods are not clearly described in the following examples, then conditions and methods known in the art may be used for processing.

[0082] According to some specific embodiments of the present invention, the method for preparing a luminescent material comprises the following steps:

[0083] S100-1: Dissolve 1 mol of the compound of formula (3-1) and 1.2 mol of the compound of formula (4-1) in ethanol, heat and stir, and perform a first reaction to produce a compound of formula (5-1). The temperature of the first reaction is 60°C to 80°C.

[0084]

[0085] The reaction formula of the first reaction is as follows:

[0086]

[0087] S200-1: 1 mol of the compound of formula (6) and 2 mol of ethanol were added to 20 mL of DMF solvent, EDC and DMAP were added, and the mixture was heated under reflux with stirring to carry out a second reaction to generate a compound of formula (8-1).

[0088] The temperature of the second reaction is 160°C to 180°C.

[0089]

[0090] The reaction formula for the second reaction is as follows:

[0091]

[0092] S300-1: 0.1 mol of the compound of formula (5-1) and 0.11 mol of the compound of formula (8-1) were added to 10 mL of DMF solvent and heated under reflux to carry out a third reaction to produce the compound of formula (1-1). The temperature of the third reaction was 160°C to 180°C and the reaction time was 6 hours.

[0093]

[0094] The reaction formula of the third reaction is as follows:

[0095]

[0096] The nuclear magnetic resonance hydrogen spectrum of the luminescent material prepared by the above reaction was tested, and the test results were as follows: Figure 2 As shown, the number and position of H atoms in the hydrogen nuclear magnetic resonance spectrum correspond one-to-one with the number and position of H atoms in the compound with the structural formula (1-1), indicating that a luminescent material with a structure that meets the requirements has been prepared.

[0097] The fluorescence emission / excitation spectrum and delayed fluorescence emission / excitation spectrum of the above luminescent materials were tested (the delay time was set to 0.1ms). The test results are as follows: Figure 3 As shown, curve 1 is the fluorescence excitation spectrum of the luminescent material, curve 3 is the fluorescence emission spectrum of the luminescent material; curve 2 is the delayed fluorescence excitation spectrum of the luminescent material, and curve 4 is the delayed fluorescence emission spectrum of the luminescent material. Figure 3 It can be seen that the fluorescence emission wavelength and the delayed fluorescence emission wavelength of the material are both 640 nm, the optimal excitation position of the fluorescence emission of the material is 580 nm, and the optimal excitation position of the delayed fluorescence emission is also 580 nm.

[0098] Figure 4 The pictures of the compound with the structural formula (1-1) under natural light, under 365nm ultraviolet light, and after irradiation with 365nm ultraviolet light for 1 minute are shown. It can be seen that the color of the material is different under different lighting conditions.

[0099] According to some other specific embodiments of the present invention, the method for preparing the luminescent material may include the following steps:

[0100] S100-2: Dissolve 1 mol of the compound of formula (3-2) and 1.2 mol of the compound of formula (4-1) in ethanol, heat and stir, and perform a first reaction to produce a compound of formula (5-2). The temperature of the first reaction is 60°C to 80°C.

[0101]

[0102] The reaction formula of the first reaction is as follows:

[0103]

[0104] S200-2: 1 mol of the compound of formula (6) and 2 mol of ethanol were added to 20 mL of DMF solvent, EDC and DMAP were added, and the mixture was heated under reflux with stirring to carry out a second reaction to generate a compound of formula (8-1).

[0105] The temperature of the second reaction is 160°C to 180°C.

[0106]

[0107] The reaction formula for the second reaction is as follows:

[0108]

[0109] S300-2: 0.1 mol of the compound of formula (5-2) and 0.11 mol of the compound of formula (8-1) were added to 10 mL of DMF solvent and heated under reflux to carry out a third reaction to produce the compound of formula (1-2). The temperature of the third reaction was 160°C to 180°C and the reaction time was 6 hours.

[0110]

[0111] The reaction formula of the third reaction is as follows:

[0112]

[0113] In another aspect of the present invention, the present invention provides a display panel. According to some embodiments of the present invention, referring to Figure 5 and Figure 6 The display panel may include a light-emitting unit 300, which may include a light-emitting layer 320. The material of the light-emitting layer 320 may include the light-emitting material described above or a light-emitting material prepared using the method described above. Thus, the display panel has all the features and advantages of the light-emitting material described above or the light-emitting material prepared using the method described above, and no further details are given here. In general, the display panel has a good display effect.

[0114] According to some embodiments of the present invention, the material of the light-emitting layer may further include a host light-emitting material. According to some embodiments of the present invention, the host light-emitting material may be a single red light-emitting material or a host-guest light-emitting system, and the host light-emitting material may include one or more of a pyran series material, a metal Ir complex, and a Pt complex.

[0115] According to some embodiments of the present invention, the main light-emitting material may include at least one of 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulidine-9-enyl)-4H-pyran (DCJTB), bis(1-phenylisoquinoline)(acetylacetonate)iridium(III) (Ir(piq)2(acac)), bis(2-(2'-benzothienyl)pyridine-N,C3')(acetylacetonate)iridium complex (Ir(btp)2(acac)), octaethylporphyrin platinum (PtOEP), etc. The above-mentioned main light-emitting materials all have good light-emitting properties. Adding the light-emitting materials mentioned above to the above-mentioned main light-emitting materials is beneficial to improving the light-emitting performance and light-emitting efficiency of the light-emitting layer, and is beneficial to extending the service life of the display panel.

[0116] According to some embodiments of the present invention, in the light-emitting layer, the mass ratio of the light-emitting material to the main light-emitting material can be 1:100 to 1:20. For example, the mass ratio of the light-emitting material to the main light-emitting material can be 1:100, 1:80, 1:50, 1:30, 1:20, etc. When the mass ratio of the light-emitting material to the main light-emitting material is within the above range, the light-emitting material can have a good effect on improving the light-emitting performance of the main light-emitting material, can significantly improve the light-emitting efficiency of the main light-emitting material, and extend the service life of the material or display panel.

[0117] According to some embodiments of the present invention, reference Figure 5 and Figure 6 , the display panel may include a plurality of light emitting units 300 .

[0118] According to some embodiments of the present invention, reference Figure 6 The display panel may further include a substrate 100 and a pixel defining layer 200, and the light-emitting unit 300 may further include an anode 310, a hole injection layer 340, a hole transport layer 350, an electron blocking layer 360, a hole blocking layer 370, an electron transport layer 380, an electron injection layer 390 and a cathode 330.

[0119] According to some embodiments of the present invention, the material of the hole injection layer 340 can be a p-type doping system with strong electron-withdrawing properties and a dopant of a hole transport material. For example, the material of the hole injection layer 340 can include at least one of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), hexacyanohexaazatriphenylene and 1,2,3-tris[(cyano)(4-cyano-2,3,5,6-tetrafluorophenyl)methylene]cyclopropane, etc.

[0120] According to some embodiments of the present invention, the material of the hole transport layer 350 may be a triphenylamine or polythiophene substance with strong electron donating properties. For example, the material of the hole transport layer 350 may include at least one of N,N'-diphenyl-N,N'-bis(3,4-difluorophenyl)-[1,1'-biphenyl]-4,4'-diamine (3,4-DFTPB) and 4,7-bis(4-hexylthiophene-2-yl)-benzothiadiazole.

[0121] According to some embodiments of the present invention, the material of the hole blocking layer 370 may be a material that can form a hole migration barrier. For example, the material of the hole blocking layer 370 may include at least one of a 1,10-phenanthroline derivative (BCP), 1,3,5-tris(N-phenyl-2-benzimidazole)benzene (TPBI), and a star-shaped aromatic benzene with 1,3,5-phenyl as the core and its derivatives.

[0122] According to some embodiments of the present invention, the material of the electron transport layer 380 may be an aromatic heterocyclic compound, such as an imidazole derivative such as a benzimidazole derivative or an imidazopyridine derivative; an azine derivative such as a triazine derivative; a compound containing a six-membered nitrogen-containing heterocyclic structure such as a quinoline / isoquinoline derivative or a phenanthroline derivative. For example, the material of the electron transport layer 380 may include at least one of 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), 3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenylyl)-1,2,4-triazole (TAZ), bathophenanthroline (BPhen), BCP, and 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (BzOs).

[0123] According to some embodiments of the present invention, the material of the electron injection layer 390 may include at least one of alkali metals, alkali metal acetates, alkali metal fluorides, etc. According to some specific embodiments of the present invention, the material of the electron injection layer 390 may include at least one of lithium oxide, potassium silicate, LiF, etc.

[0124] According to some embodiments of the present invention, the material of anode 310 may include ITO (indium tin oxide). According to other embodiments of the present invention, anode 310 may be a multi-layer structure, for example, anode 310 may include an ITO layer, a silver layer, and an ITO layer stacked in sequence.

[0125] According to some embodiments of the present invention, the material of cathode 330 may include at least one of aluminum and silver.

[0126] Three display devices were fabricated. The first display device did not include the luminescent material of the present invention in its luminescent layer. The second display device included a compound having the structural formula (1-1) in its luminescent layer. The third display device included a compound having the structural formula (1-2) in its luminescent layer. The first display device was designated as Device 1, the second display device as Device 2, and the third display device as Device 3. The three display devices differed only in the material used in the luminescent layer; the materials used in the other layers were identical. The HOMO (highest occupied molecular orbital) energy level, LUMO (lowest unoccupied molecular orbital) energy level, and emission spectra of the luminescent layer materials of the three display devices were tested. The results are recorded in Table 1 below.

[0127] Table 1 Performance test results of the light-emitting layer materials in three display devices

[0128] Material name ∣HOMO∣ ∣LUMO∣ Emission spectrum peak wavelength Material of the light-emitting layer of device 1 5.55eV 2.70eV 622nm Material of the light-emitting layer of device 2 5.61eV 2.65eV 640nm Material of the light-emitting layer of device 3 5.59eV 2.65eV 638nm

[0129] It should be noted that the HOMO and LUMO energy levels of the materials tested in Table 1 are both negative. The higher the absolute value of the HOMO energy level and the lower the absolute value of the LUMO energy level, the more beneficial it is for improving the luminous efficiency of the light-emitting layer. As shown in Table 1, adding the compound of structural formula (1-1) or the compound of structural formula (1-2) to the light-emitting layer is beneficial for improving the luminous efficiency. In addition, the peak wavelengths of the emission spectra are all within the red wavelength range, indicating that the light-emitting layer materials of the three display devices can emit red light.

[0130] Test the luminous efficiency, LT95 (the time from the initial brightness to 95% of the initial brightness, the initial brightness is 1000nit), LT 90％-10％ (The time taken for the brightness to drop from 90% of the initial brightness to 10% of the initial brightness). The test data of device 2 and device 3 are normalized with the test data of device 1 as the benchmark. The normalized test data are recorded in Table 2.

[0131] Table 2 Luminous efficiency, LT95 and LT of three display devices 90％-10％ Test results

[0132] Device Name Luminous efficiency LT95 <![CDATA[LT 90％ -10%]]> Device 1 100％ 100％ 100％ Device 2 110％ 101％ 138％ Device 3 108％ 98％ 126％

[0133] As shown in Table 2, compared with device 1, the light-emitting layer of devices 2 and 3 is added with the compound of structural formula (1-1) and the compound of structural formula (1-2), respectively. The luminous efficiency of devices 2 and 3 is significantly improved, the LT95 of devices 2 and 3 is roughly the same as that of device 1, and the transient lifetime LT of devices 2 and 3 is 90％-10％ It can be seen that adding the luminescent material proposed in the present invention to the luminescent layer is beneficial to improving the luminous efficiency of the display device and extending the service life of the display device.

[0134] In another aspect of the present invention, a display device is provided. According to some embodiments of the present invention, the display device may include the display panel described above. Thus, the display device has a better display effect and a longer service life.

[0135] According to the embodiment of the present invention, there is no special requirement for the specific type of the above-mentioned display device, and those skilled in the art can flexibly select it according to actual needs. For example, it can be a mobile phone, iPad, notebook or other display device.

[0136] Those skilled in the art will understand that, in addition to the display panel described above, the display device may also have the necessary structures and components of a conventional display device. Taking a mobile phone as an example, in addition to the display panel described above, it may also include necessary structures and components such as a battery back cover, a middle frame, a touch panel, an audio module, and a motherboard.

[0137] In the description of the present invention, “plurality” means two or more than two, unless otherwise clearly defined.

[0138] In the description of this specification, the reference terms "one embodiment", "another embodiment", "some embodiments", "some specific embodiments" or "some other specific embodiments" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0139] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A luminescent material, characterized in that: Including a compound of formula (1), Wherein, X is a halogen element, R1 is a C1-C2 alkyl group substituted with a hydroxyl group, and R2 is an unsubstituted C1-C2 alkyl group.

2. The luminescent material according to claim 1, characterized in that The luminescent material includes a compound having a structural formula (1-1), 3. The luminescent material according to claim 1, characterized in that The luminescent material includes a compound having a structural formula (1-2), 4. A method for preparing a luminescent material, characterized in that: include: The compound of formula (3) and the compound of formula (4) undergo a first reaction to generate a compound of formula (5). The compound of formula (6) undergoes a second reaction with the compound of formula (7) to generate a compound of formula (8). The compound of formula (5) and the compound of formula (8) undergo a third reaction to generate a compound of formula (1). Wherein, X is a halogen element, R1 is a C1-C2 alkyl group substituted with a hydroxyl group, and R2 is an unsubstituted C1-C2 alkyl group.

5. The method according to claim 4, characterized in that At least one of the following conditions is met: The solvent for the first reaction includes ethanol; The temperature of the first reaction is 60°C to 80°C; The solvent for the second reaction includes N,N-dimethylformamide; The temperature of the second reaction is 160°C to 180°C; The catalyst for the second reaction includes at least one of 4-dimethylaminopyridine and 1-ethyl-(3-dimethylaminopropyl)carbodiimide; In the second reaction, the ratio of the mass of the catalyst to the mass of the compound having the structural formula (6) is 1:100 to 1:20; The solvent for the third reaction includes N,N-dimethylformamide; The temperature of the third reaction is 160°C to 180°C.

6. The method according to claim 4, characterized in that The compound of formula (3-1) and the compound of formula (4-1) undergo a first reaction to generate a compound of formula (5-1). The compound of formula (6) undergoes a second reaction with ethanol to generate a compound of formula (8-1). The compound of formula (5-1) and the compound of formula (8-1) undergo a third reaction to generate a compound of formula (1-1).

7. The method according to claim 4, characterized in that The compound of formula (3-2) and the compound of formula (4-1) undergo a first reaction to generate a compound of formula (5-2). The compound of formula (6) undergoes a second reaction with ethanol to generate a compound of formula (8-1). The compound of formula (5-2) undergoes a third reaction with the compound of formula (8-1) to generate a compound of formula (1-2).

8. The method according to any one of claims 4 to 7, characterized in that During the reaction, the substances in the reaction system were tested by thin layer chromatography to determine whether the raw materials had reacted completely.

9. A display panel, characterized in that: The invention comprises a light-emitting unit, wherein the light-emitting unit comprises a light-emitting layer, and the material of the light-emitting layer comprises the light-emitting material according to any one of claims 1 to 3 or the light-emitting material prepared by the method according to any one of claims 4 to 8.

10. The display panel according to claim 9, wherein the material of the light-emitting layer further comprises a main light-emitting material, and the main light-emitting material comprises at least one of 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulonitrile-9-enyl)-4H-pyran, bis(1-phenylisoquinoline)(acetylacetonate)iridium(III), bis(2-(2'-benzothienyl)pyridine-N,C3')(acetylacetonate)iridium, and octaethylporphyrin platinum. 11 . The display panel according to claim 10 , wherein in the light-emitting layer, a mass ratio of the light-emitting material to the main light-emitting material is 1:100 to 1:

20.

12. A display device, characterized in that: A display panel comprising the display panel according to any one of claims 9 to 11.

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