Organic long-afterglow luminescent material capable of enhancing luminescence as well as preparation method and application of organic long-afterglow luminescent material

Abstract

The invention provides an organic long-afterglow luminescent material capable of enhancing luminescence and a preparation method and application thereof, and belongs to the technical field of organic photoelectric materials, and the organic long-afterglow luminescent material comprises a donor material based on a carbazole derivative and an acceptor material based on a phenanthrene derivative, the donor material based on the carbazole derivative is PVK, TCP, mCP-CN, 26DCzPPy, SBF-Cz, SP-Cz and the like. According to the invention, a bi-component form constructed by a donor material based on a carbazole derivative and an acceptor material based on a phenanthrene derivative is adopted, stable long-life luminescence in an air atmosphere is realized by utilizing intermolecular charge transfer between the bi-components, luminescence with two properties of TADF and long life is realized, and after irradiation of a 365nm ultraviolet fluorescent lamp is turned off, the luminescence effect is good. The material can continuously emit light for more than several seconds, has excellent fluorescence quantum yield and attenuation life, and can be used for anti-counterfeiting and information encryption.

Description

Technical Field

[0001] The invention belongs to the technical field of organic photoelectric materials, and in particular relates to an organic long afterglow luminescent material with enhanced luminescence, a preparation method and an application thereof. Background Art

[0002] Long afterglow luminescent materials have attracted extensive attention due to their unique photon absorption, storage and release capabilities. They are widely used in many fields such as organic light-emitting diodes, sensor detection, information storage, data encryption, display anti-counterfeiting and biological imaging, and have become one of the current research hotspots. At present, long afterglow luminescent systems are still mainly limited to inorganic materials, but due to the harsh processing conditions of inorganic long afterglow luminescent materials, the high price of heavy metal materials, and the toxicity of rare earth ions and heavy metals, their further application is limited. Therefore, it is extremely urgent and critical to develop organic long afterglow luminescent materials that are easy to prepare and have excellent luminescence performance.

[0003] The long-life luminescence of organic long-lasting luminescent materials reported so far mainly comes from room temperature phosphorescence, thermally activated delayed fluorescence (TADF) or both. Phosphorescence emission refers to the process in which triplet excitons return to the ground state through radiative transition to emit light; TADF refers to the process in which triplet excitons are converted into singlet excitons through the reverse intersystem crossing process, and then return to the ground state through radiative transition to emit light. However, in organic luminescent molecular systems, long-life triplet excitons are easily quenched by oxygen components in the air environment, and there is rapid non-radiative vibrational relaxation. In order to develop effective organic long-lasting luminescent materials, researchers have proposed a variety of effective design strategies such as halogen bonding in eutectics, crystallization-induced phosphorescence, introduction of heavy metal atoms, heteroatom (N, O, P, S) induction, host-guest doping, H-aggregate enhanced phosphorescence, polymer matrix and self-assembly. However, compared with inorganic long-lasting luminescent materials, these organic long-lasting luminescent materials still require specific molecular structures to achieve; at the same time, the luminescence efficiency and decay life of organic long-lasting luminescent materials designed based on these advanced strategies are still far from enough. Therefore, there is an urgent need to develop an organic long afterglow luminescence system with high luminescence efficiency and long decay life. Summary of the invention

[0004] In response to the problems of low luminous efficiency and lifespan of some organic long afterglow materials, the present invention provides an organic long afterglow luminescent material with enhanced luminescence, and a preparation method and application thereof, which utilizes intermolecular charge transfer between two components to achieve stable long-life luminescence in an air atmosphere, successfully solving the problems of insufficient luminous efficiency and attenuation lifespan of a single-component acceptor luminescent system.

[0005] In order to achieve the above purpose, the technical method adopted by the present invention is as follows:

[0006] An organic long afterglow luminescent material with enhanced luminescence, comprising a donor material based on a carbazole derivative and an acceptor material based on a phenanthrene derivative;

[0007] The structure of the receptor material based on phenanthrene derivatives is shown in formula (I):

[0008]

[0009] Wherein, R1 and R2 are both cyano groups; L1 and L2 are the same and are selected from dibenzo[b,d]furan, dibenzo[b,d]thiophene, benzophenone, thianthrene, substituted C6, C12 or C18 aryl groups, and substituted heteroaryl groups;

[0010] The donor material based on carbazole derivatives is one of PVK, TCP, mCP-CN, 26DCzPPy, SBF-Cz, SP-Cz and a material having a structure as shown in formula (II);

[0011]

[0012] Here, n represents the number of benzene rings, which is a natural number.

[0013] Furthermore, the structural formulas of PVK, TCP, mCP-CN, 26DCzPPy, SBF-Cz and SP-Cz are respectively:

[0014]

[0015] Furthermore, the mass fraction of the acceptor material based on phenanthrene derivatives is 0.5-10wt%.

[0016] Furthermore, the receptor material based on phenanthrene derivatives is specifically a material of the following formulas 1 to 21:

[0017]

[0018] A method for preparing an organic long afterglow luminescent material with enhanced luminescence, the specific process is: firstly dissolving a donor material based on a carbazole derivative and an acceptor material based on a phenanthrene derivative into an organic solvent, then coating the obtained mixed solution on the surface of a substrate, and heat treating the mixture at 50-70°C until the organic solvent evaporates to obtain the luminescent material;

[0019] The preparation process of the receptor material based on phenanthrene derivatives comprises the following steps:

[0020] Step 1: Perform a carbonyl protection reaction on 2,7-dibromophenanthrene-9,10-dione and 2-nitropropane to obtain an intermediate compound C1;

[0021] Step 2: Performing a carbon-carbon coupling reaction based on the intermediate compound C1, the substituent L1 and a palladium catalyst to obtain an intermediate compound C2;

[0022] Step 3, performing carbonyl deprotection reaction of the intermediate compound C2 under strong acidic conditions to obtain the intermediate compound C3;

[0023] Step 4: Perform a dehydration condensation reaction on the intermediate compound C3 and 2,3-diamino-2-butenedinitrile to obtain the receptor material based on the phenanthrene derivative.

[0024] Furthermore, the organic solvent is dichloromethane, toluene or tetrahydrofuran.

[0025] Furthermore, the intermediate compound C1, intermediate compound C2 and intermediate compound C3 are specifically materials of the following structural formulas:

[0026]

[0027] Furthermore, the specific process of step 1 is:

[0028] Under nitrogen protection, 2,7-dibromophenanthrene-9,10-dione, 2-nitropropane and the first organic solvent are added in sequence to a double-necked flask with a stirring magnet, and the mixture is reacted at a heating temperature of 60 to 80° C. for 18 to 36 hours. A precipitate is precipitated in ice water, and an intermediate compound C1 is obtained after drying; wherein the molar ratio of 2,7-dibromophenanthrene-9,10-dione to 2-nitropropane is 1:1 to 1.5.

[0029] Furthermore, the first organic solvent is an acetonitrile aqueous solution.

[0030] Furthermore, the specific process of step 2 is:

[0031] Under nitrogen protection, the intermediate compound C1, the substituent L1, the palladium catalyst and the mixed solvent are added in sequence to a two-necked flask with a stirring magnet, and the reaction is carried out at a heating condition of 80 to 120° C. for 18 to 36 hours. After sequential evaporation, elution, purification, recrystallization, filtration, drying and step-by-step heating sublimation, the intermediate compound C2 is obtained; wherein the molar ratio of the intermediate compound C1, the substituent L1 and the palladium catalyst is 1:1.1 to 1.5:0.1 to 0.3.

[0032] Furthermore, the mixed solvent is a mixed solution of ethylene glycol dimethyl ether solution and super-dry 1,4-dioxane.

[0033] Furthermore, the specific process of step 3 is:

[0034] In ice water area and under nitrogen protection, a strong acidic solvent is injected into the intermediate compound C2, and the reaction is first carried out in ice water area for 2 to 4 hours, and then the temperature is raised to room temperature for reaction for 2 to 4 hours. An alkaline solvent is slowly added until the pH is neutral. After filtration and vacuum drying, the intermediate compound C3 is obtained.

[0035] Furthermore, the strong acidic solvent is concentrated nitric acid or trifluoromethanesulfonic acid, etc.; the alkaline solvent is a sodium hydroxide (NaOH) aqueous solution.

[0036] Furthermore, the specific process of step 4 is:

[0037] Under nitrogen protection, the intermediate compound C3, 2,3-diamino-2-butenedinitrile and acetic acid solution are added in sequence to a double-necked flask with a stirring magnet, and the mixture is reacted at a heating temperature of 110 to 130° C. for 24 to 36 hours. After the reaction, the mixture is extracted, dried, eluted, purified, recrystallized, filtered, dried and step-wise sublimated to obtain the receptor material based on phenanthrene derivatives; wherein the molar ratio of the intermediate compound C3 to 2,3-diamino-2-butenedinitrile is 1:1.0 to 1.5.

[0038] The present invention also provides application of the organic long afterglow luminescent material with enhanced luminescence in an organic electroluminescent device.

[0039] Furthermore, the organic electroluminescent device comprises an anode, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer and a cathode stacked in sequence; wherein the material of the light-emitting layer is the organic long afterglow light-emitting material with enhanced luminescence.

[0040] Furthermore, the hole transport layer, electron blocking layer, light-emitting layer, hole blocking layer and electron transport layer are prepared by vacuum evaporation, spin coating, inkjet printing or large-area scraping.

[0041] Furthermore, the anode is any one of indium tin oxide (ITO) or indium zinc oxide (ITZ); the hole transport layer is a hole transport material with a suitable triplet energy level and a highest occupied orbital energy level, wherein the hole transport material for preparing a vacuum evaporation method device is a common hole transport material, and the hole transport material for preparing a solution method device is a PEDOT:PSS (8000) solution with good hole transport ability; the electron transport material is a pyridine derivative-based compound 4,6-di(3,5-di-4-pyridylphenyl)-2-methylpyrimidine (B4PyMPM); the cathode is any one of Al, Ag, Au or Liq (8-hydroxyquinoline lithium) / Al, LiF (lithium fluoride) / Al, MgZnO (magnesium zinc oxide) / Al.

[0042] Furthermore, the organic electroluminescent device is tested under an external bias voltage.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1. The present invention proposes an organic long afterglow luminescent material with enhanced luminescence, a preparation method and application thereof, which adopts a two-component form constructed by a donor material based on a carbazole derivative and an acceptor material based on a phenanthrene derivative, and utilizes the intermolecular charge transfer between the two components to achieve stable long-life luminescence in an air atmosphere, and has both TADF and long-life luminescence properties. After the 365nm ultraviolet fluorescent lamp is turned off, it can show continuous luminescence for more than a few seconds, has excellent fluorescence quantum yield and decay life, and can be used for anti-counterfeiting and information encryption;

[0045] 2. The receptor material based on phenanthrene derivatives designed in the present invention has a completely planar conjugated structure and strong π electron-withdrawing properties, a novel molecular structure, and a high expandability. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0047] Figure 1 The UV-visible light photophysical property spectrum of the phenanthrene derivative-based acceptor material having the structure of Formula 10 obtained in Example 1 of the present invention at room temperature;

[0048] Figure 2 The photophysical properties of the receptor material based on phenanthrene derivatives with the structure of Formula 10 obtained in Example 1 of the present invention are shown in Figure 1: (a) is a temperature-dependent fluorescence quantum yield diagram; (b) is a transient fluorescence spectrum diagram;

[0049] Figure 3 The UV-visible light photophysical property spectrum of the phenanthrene derivative-based acceptor material having the structure of Formula 12 obtained in Example 2 of the present invention at room temperature;

[0050] Figure 4 The photophysical properties of the receptor material based on phenanthrene derivatives with the structure of Formula 12 obtained in Example 2 of the present invention are shown in Figure 1: (a) is a temperature-dependent fluorescence quantum yield diagram; (b) is a transient fluorescence spectrum diagram;

[0051] Figure 5The photophysical property spectrum of the acceptor material based on phenanthrene derivatives and the donor material mCBP having the structure of Formula 10 obtained in Example 1 of the present invention and the organic long afterglow luminescent material mCBP:10 composed of the two at room temperature;

[0052] Figure 6 The photophysical properties of the organic long afterglow luminescent material mCBP:10 composed of the acceptor material based on phenanthrene derivatives and the donor material mCBP having the structure of Formula 10 obtained in Example 1 of the present invention: wherein (a) is a temperature-dependent fluorescence quantum yield diagram; (b) is a transient fluorescence spectrum diagram;

[0053] Figure 7 The efficiency diagram of the organic electroluminescent device of the organic long afterglow luminescent material mCBP:10 composed of the acceptor material based on the phenanthrene derivative having the structure of formula 10 obtained in Example 1 of the present invention and the donor material mCBP; wherein (a) is voltage-brightness-current density; (b) is brightness-power efficiency-external quantum efficiency; (c) is wavelength-electroluminescence spectrum;

[0054] Figure 8 The photophysical property spectrum of the acceptor material based on phenanthrene derivatives and the donor material mCBP having the structure of formula 12 obtained in Example 2 of the present invention and the organic long afterglow luminescent material mCBP:12 composed of the two at room temperature;

[0055] Fig. 9 The photophysical properties of the organic long afterglow luminescent material mCBP:12 composed of the acceptor material based on phenanthrene derivatives and the donor material mCBP of the structure 12 obtained in Example 2 of the present invention: wherein (a) is a temperature-dependent fluorescence quantum yield diagram; (b) is a transient fluorescence spectrum diagram;

[0056] Fig.10 The efficiency diagram of the organic electroluminescent device of the organic long afterglow luminescent material mCBP:12 composed of the acceptor material based on the phenanthrene derivative having the structure of formula 12 obtained in Example 2 of the present invention and the donor material mCBP; wherein (a) is voltage-brightness-current density; (b) is brightness-power efficiency-external quantum efficiency; (c) is wavelength-electroluminescence spectrum;

[0057] Fig.11 This is the afterglow pattern of the organic long afterglow luminescent material mCBP:12 composed of the acceptor material based on phenanthrene derivatives with the structure of Formula 12 obtained in Example 2 of the present invention and the donor material mCBP. DETAILED DESCRIPTION

[0058] In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with the examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the invention. All raw materials of the present invention are not particularly limited in their sources, and can be purchased on the market or prepared according to conventional methods well known to those skilled in the art.

[0059] The present invention provides an organic long afterglow luminescent material with enhanced luminescence, comprising a donor material based on a carbazole derivative and an acceptor material based on a phenanthrene derivative. The structure of the acceptor material based on the phenanthrene derivative is shown in formula (I):

[0060]

[0061] The present invention focuses on providing a general preparation method for the receptor material based on phenanthrene derivatives, and the synthesis route is as follows:

[0062]

[0063] The specific steps include:

[0064] Step 1. Add 2,7-dibromophenanthrene-9,10-dione (363.87 mg, 1 mmol) to a 100 mL double-necked round-bottom flask with a magnetic stirrer, replace nitrogen three times, and under the protection of nitrogen, use a 50 mL syringe to extract 19 mL of 2-nitropropane, 30 mL of acetonitrile and 35 mL of a mixed solution of deionized water and inject it into the round-bottom flask, and react at an oil bath temperature of 60° C. for 24 hours; use thin layer chromatography spot plate detection, cool to room temperature, pour into ice water, and filter and dry the precipitate to obtain a crude product, i.e., intermediate compound C1;

[0065] Step 2, add intermediate compound C1 (361.2 mg, 1 mmol), substituent L1 (2.2 mmol) and tetrakis(triphenylphosphine)palladium (115.56 mg, 0.1 mmol) to a 100 mL double-mouthed round-bottom flask with a magnetic stirrer, replace nitrogen three times, and then inject 10 mL of 2M ethylene glycol dimethyl ether solution and 30 mL of ultra-dry 1,4-dioxane in sequence under the protection of nitrogen, and react at an oil bath temperature of 90 ° C for 24 hours; use thin layer chromatography spot plate detection. After cooling to room temperature, remove 1,4-dioxane and water with a rotary evaporator, and then use a mixed solution of methanol and dichloromethane with a volume ratio of 1:20 as an eluent, purify the mixture by silica gel column chromatography, and finally recrystallize with a mixed solution of dichloromethane and n-hexane, and after suction filtration and drying, further purify by temperature gradient sublimation in a vacuum to obtain a pure yellow powder material, that is, intermediate compound C2.

[0066] Step 3, add intermediate compound C2 (460.0mg, 1mmol) to the dried double-mouthed round-bottom flask, place the reaction bottle in an ice water area, replace nitrogen three times, and then inject 5mL concentrated nitric acid under the protection of nitrogen. First, the reaction is carried out under ice water conditions for 2 hours, then heated to room temperature and reacted for 4 hours, and the reaction is cooled to room temperature after the reaction is completed, and sodium hydroxide aqueous solution is slowly added thereto, and it is detected to neutrality by PH test paper, and sodium hydroxide aqueous solution is stopped. Finally, a funnel is used for suction filtration, and the obtained solid is placed in a vacuum drying oven for drying. Finally, a reddish-brown solid material, i.e., intermediate compound C3, is obtained.

[0067] Step 4: Add the intermediate compound C3 (230 mg, 0.5 mmol) and 2,3-diamino-2-butenedinitrile (54 mg, 0.5 mmol) to a 100 mL double-mouth round-bottom flask with a magnetic stirrer, and then inject 30 mL of acetic acid solution with a mass fraction of 30%, and react for 24 hours at an oil bath temperature of 110 ° C; detect by thin layer chromatography. After cooling to room temperature, extract with a separatory funnel to obtain a crude purified product, then use a rotary evaporator for drying, and then use a mixed solution of petroleum ether and ethyl acetate with a volume ratio of 2: 1 as an eluent to purify the final product of the mixture by silica gel column chromatography, and finally recrystallize with a mixed solution of dichloromethane and n-hexane, and after suction filtration and drying, further purify by temperature gradient sublimation in a vacuum to obtain the final product C4, that is, the receptor material based on phenanthrene derivatives.

[0068] Example 1

[0069] This embodiment provides an organic long afterglow luminescent material with enhanced luminescence, including a donor material based on a carbazole derivative and an acceptor material based on a phenanthrene derivative.

[0070] The receptor material based on phenanthrene derivatives adopts the structure of Formula 10, as shown below:

[0071]

[0072] The synthetic route is as follows:

[0073]

[0074] The specific steps include:

[0075] S1: 2,7-dibromophenanthrene-9,10-dione (363.87 mg, 1 mmol) was added to a 100 mL double-necked round-bottom flask with a magnetic stirrer, and nitrogen was replaced three times. Under the protection of nitrogen, a 50 mL syringe was used to draw a mixture of 19 mL of 2-nitropropane, 35 mL of acetonitrile and 35 mL of deionized water and injected into the round-bottom flask. The mixture was reacted at an oil bath temperature of 60°C for 24 hours. The mixture was detected by thin layer chromatography spot plate. After cooling to room temperature, the mixture was poured into ice water. The precipitated precipitate was filtered and dried to obtain a crude product P1.

[0076] S2: Into a 100mL double-necked round-bottom flask with a magnetic stirrer, the intermediate compound P1 (361.2mg, 1mmol), 2,6-dimethylphenylboronic acid (330.2mg, 2.2mmol) and tetrakis(triphenylphosphine)palladium (115.56mg, 0.1mmol) were added, the nitrogen was replaced three times, and then under the protection of nitrogen, 10mL of 2M ethylene glycol dimethyl ether solution and 30mL of ultra-dry 1,4-dioxane were injected in sequence, and the reaction was carried out at an oil bath temperature of 90°C for 24 hours; the reaction was detected by thin layer chromatography spot plate. After cooling to room temperature, 1,4-dioxane and water were removed by a rotary evaporator, and then the mixture P2 was purified by silica gel column chromatography using a mixed solution of methanol and dichloromethane in a volume ratio of 1:20 as an eluent, and finally recrystallized with a mixed solution of dichloromethane and n-hexane. After suction filtration and drying, it was further purified by temperature gradient sublimation in a vacuum to obtain a pure yellow powder material (391 mg) with a yield of 85%.

[0077] S3: Add intermediate compound P2 (460.0 mg, 1 mmol) to a dried double-mouth round-bottom flask, place the reaction bottle in an ice water area, replace nitrogen three times, and then inject 5 mL of concentrated nitric acid under the protection of nitrogen. First, the reaction was carried out under ice water conditions for 2 hours, and then heated to room temperature for 4 hours. After the reaction was completed and cooled to room temperature, sodium hydroxide (NaOH) aqueous solution was slowly added thereto, and it was detected to neutrality by PH test paper, and the addition of NaOH solution was stopped. Finally, a funnel was used for suction filtration, and the obtained solid was placed in a vacuum drying oven for drying. Finally, a reddish-brown solid material (349.6 mg), i.e., intermediate compound P3, was obtained with a yield of 76%.

[0078] S4: The intermediate compound P3 (230 mg, 0.5 mmol) and 2,3-diamino-2-butenedinitrile (54 mg, 0.5 mmol) were added to a 100 mL double-mouth round-bottom flask with a magnetic stirrer, and then 30 mL of acetic acid solution was injected, and the reaction was carried out at an oil bath temperature of 110°C for 24 hours; the reaction was detected by thin layer chromatography. After cooling to room temperature, the crude purified product was extracted using a separatory funnel, and then dried using a rotary evaporator. The mixture was purified by silica gel column chromatography using a mixed solution of petroleum ether and ethyl acetate in a volume ratio of 2:1 as an eluent, and the final product 10 was purified by a mixed solution of dichloromethane and n-hexane. Finally, the mixture was recrystallized with a mixed solution of dichloromethane and n-hexane, and after suction filtration and drying, it was further purified by temperature gradient sublimation in a vacuum to obtain a light yellow powder of the final product, i.e., a phenanthrene derivative-based receptor material (366.0 mg) with a structure of formula 10, and a yield of 75%. HRMS (ESI) m / z:calcd for: C34H 24 N4, (M) + :488.2050; found:488.2034.

[0079] The acceptor material based on phenanthrene derivatives having the structure of Formula 10 obtained in this embodiment was prepared into a pure film by vacuum evaporation. The film was tested at room temperature and irradiated with a 365 nm ultraviolet lamp. Figure 1 The UV-visible light physical property spectrum shown in FIG. 1 shows that the material emits sky blue light, with a fluorescence peak at 490nm and a room temperature phosphorescence peak at 560nm. The transient fluorescence spectrum test results are as follows: Figure 2 As shown, Figure 2 (a) is the fluorescence quantum yield (PLQY) at room temperature, specifically 50.1%. Figure 2 (b) in the figure is the luminescence lifetime at room temperature, which is 12.7 ms.

[0080] The donor material based on carbazole derivatives used in this embodiment is 1,3-di(9H-carbazole-9-yl)benzene mCBP, and its chemical structure is as follows:

[0081]

[0082] Furthermore, the specific process of the organic long afterglow luminescent material with enhanced luminescence is: firstly dissolving a donor material based on carbazole derivatives and an acceptor material based on phenanthrene derivatives into a dichloromethane solution, then dropping the obtained mixed solution on the surface of a quartz plate, and heat treating at 60°C for 5 minutes to evaporate the organic solvent, thereby obtaining the organic long afterglow luminescent material mCBP:10; wherein the mass fraction of the acceptor material based on phenanthrene derivatives is 1wt%.

[0083] The absorption and emission spectra of the acceptor material based on phenanthrene derivatives and the donor material mCBP and the organic long afterglow luminescent material mCBP:10 composed of the two materials obtained in this embodiment are tested at room temperature. The results are as follows: Figure 5 As shown, compared with the acceptor material based on phenanthrene derivatives and the donor material mCBP with the structure of formula 10, the organic long afterglow luminescent material mCBP:10 does not present a new absorption peak, indicating that no new excited state transition is formed. At the same time, compared with the donor material mCBP with an emission peak at 371nm and the acceptor material based on phenanthrene derivatives with the structure of formula 10 with an emission peak at 490nm, the emission peak of the organic long afterglow luminescent material mCBP:10 is at 534nm, with an obvious spectral red shift.

[0084] The organic long afterglow luminescent material mCBP:10 obtained in this example was tested for variable temperature spectral transient fluorescence spectroscopy. The results are as follows: Figure 6 As shown, Figure 6 (a) is the temperature-dependent fluorescence quantum yield diagram. Figure 6 (b) is a transient fluorescence spectrum, from which it can be seen that the decay lifetime of the obtained organic long afterglow luminescent material mCBP:10 is 24.1 ms at room temperature 300K, and the PLQY is 95.5%, indicating that it has both thermally activated delayed fluorescence and room temperature phosphorescence luminescence properties.

[0085] In addition, this embodiment also prepares an organic electroluminescent device based on the obtained organic long afterglow luminescent material mCBP:10, including an ITO conductive substrate, a 40nm thick TAPC hole transport layer, a 10nm thick mCBP electron blocking layer, a 30nm thick light-emitting layer, a 55nm thick B4PyMPM electron transport layer (also serving as a hole blocking layer), a 1nm thick LiF electron injection layer and a 100nm thick Al cathode electrode, which are arranged in sequence from bottom to top; wherein the material of the light-emitting layer is the obtained organic long afterglow luminescent material mCBP:10, and the mass fraction of the acceptor material based on phenanthrene derivatives is 10wt%.

[0086] The preparation process of the organic electroluminescent device is as follows:

[0087] Q1: Pretreatment of ITO conductive substrate:

[0088] A substrate with a size of 32 mm×32 mm and a striped indium tin oxide (ITO) film pattern transparent electrode is selected as an ITO conductive substrate;

[0089] The ITO conductive substrate was sequentially placed in a cleaning agent, deionized water, acetone, and anhydrous ethanol, each of which was ultrasonicated for 30 minutes, and then the residual solvent on the surface was blown off with a nitrogen gun and ultraviolet treatment was performed with an ultraviolet ozone instrument for 15 minutes;

[0090] Q2: Fabrication of organic electroluminescent devices:

[0091] Place the pretreated ITO conductive substrates into the slots of the evaporation instrument chamber and start evacuating to 5×10 -4 Pa;

[0092] According to the pre-designed device structure, the materials of the hole transport layer, electron blocking layer, light-emitting layer, and electron transport layer are heated by resistance heating. The deposition rate is set to vacuum evaporate layer by layer to form films in sequence; wherein, the ITO conductive substrate is used as the anode; the vacuum evaporated TAPC with a thickness of 40nm is used as the hole transport layer, the mCBP with a thickness of 10nm is used as the electron blocking layer, the organic long afterglow luminescent material mCBP:10 with a thickness of 30nm is used as the light-emitting layer, the B4PyMPM with a thickness of 55nm is used as the electron transport layer, a metal mask is arranged in a manner orthogonal to the ITO stripes to form a cathode, the lithium fluoride with a thickness of 1nm is used as the electron injection layer; and the aluminum with a thickness of 100nm is used as the cathode.

[0093] Q3: The prepared organic electroluminescent device is sealed and stored in a glove box filled with nitrogen with a water oxygen concentration below 0.5 ppm, and then the prepared light-emitting device is encapsulated with a glass sealing cover containing epoxy-type ultraviolet curing resin and sealed with UV 365nm ultraviolet curing.

[0094] A direct current was applied to the prepared organic electroluminescent device based on the obtained organic long afterglow luminescent material mCBP:10 using a Keithley 2400 digital source meter, and the luminescence performance was evaluated using a Spectrascan PR655 luminance meter; the current-voltage characteristics were measured using a Keithley 2400 digital source meter, and the device performance was determined when the applied direct current voltage changed.

[0095] Figure 7 is the efficiency result of the organic electroluminescent device obtained in this example, wherein: Figure 7 (a) is voltage-brightness-current density, Figure 7 (b) is the brightness-power efficiency-external quantum efficiency, Figure 7 (c) is the wavelength-electroluminescence spectrum, and the performance data shown in Table 1 are obtained by statistics. It can be seen that the obtained organic electroluminescent device has excellent luminescence performance.

[0096] Table 1

[0097]

[0098] Example 2

[0099] This embodiment provides an organic long afterglow luminescent material with enhanced luminescence, including a donor material based on a carbazole derivative and an acceptor material based on a phenanthrene derivative.

[0100] The receptor material based on phenanthrene derivatives adopts the structure of Formula 12, as shown below:

[0101]

[0102] The synthetic route is as follows:

[0103]

[0104] The specific steps include:

[0105] S1: Add 2,7-dibromophenanthrene-9,10-dione (363.87 mg, 1 mmol) to a 100 mL double-necked round-bottom flask with a magnetic stirrer, replace nitrogen three times, and under the protection of nitrogen, use a 50 mL syringe to draw 19 mL of 2-nitropropane, 35 mL of acetonitrile and 35 mL of deionized water (1:1 volume ratio) and inject it into the round-bottom flask, and react at an oil bath temperature of 60 ° C for 24 hours; use thin layer chromatography spot plate detection, cool to room temperature, pour into ice water, and filter and dry the precipitate to obtain crude M1.

[0106] S2: Into a 100mL double-necked round-bottom flask with a magnetic stirrer, the intermediate compound M1 (361.2mg, 1mmol), [1,1':3',1'-triphenyl]-2'-boronic acid (330.2mg, 2.2mmol) and tetrakis(triphenylphosphine)palladium (115.56mg, 0.1mmol) were added, the nitrogen was replaced three times, and then 10mL of 2M ethylene glycol dimethyl ether solution and 30mL of ultra-dry 1,4-dioxane were injected in sequence under the protection of nitrogen, and the reaction was carried out at an oil bath temperature of 90°C for 24 hours; the reaction was detected by thin layer chromatography spot plate. After cooling to room temperature, 1,4-dioxane and water were removed by a rotary evaporator, and then the mixture M2 was purified by silica gel column chromatography using a mixed solution of methanol and dichloromethane in a volume ratio of 1:20 as an eluent, and finally recrystallized with a mixed solution of dichloromethane and n-hexane. After suction filtration and drying, it was further purified by temperature gradient sublimation in a vacuum to obtain a pure yellow powder material (482 mg), i.e., the intermediate compound M2, with a yield of 68%.

[0107] S3: Add intermediate compound M2 (460.0 mg, 1 mmol) to a dried double-mouth round-bottom flask, place the reaction bottle in an ice water area, replace nitrogen three times, and then inject 5 mL of concentrated nitric acid under the protection of nitrogen. First, the reaction was carried out under ice water conditions for 2 hours, and then heated to room temperature for 4 hours. After the reaction was completed and cooled to room temperature, sodium hydroxide (NaOH) aqueous solution was slowly added thereto, and it was detected to neutrality by PH test paper, and the addition of NaOH solution was stopped. Finally, a funnel was used for suction filtration, and the obtained solid was placed in a vacuum drying oven for drying. Finally, a reddish-brown solid material (445.4 mg), i.e., intermediate compound M3, was obtained with a yield of 67%.

[0108] S4: The intermediate compound M3 (230 mg, 0.5 mmol) and 2,3-diamino-2-butenedinitrile (54 mg, 0.5 mmol) were added to a 100 mL double-mouth round-bottom flask with a magnetic stirrer, and then 30 mL of acetic acid solution was injected, and the reaction was carried out at an oil bath temperature of 110°C for 24 hours; the reaction was detected by thin layer chromatography. After cooling to room temperature, the crude purified product was extracted using a separatory funnel, and then dried using a rotary evaporator. Then, a mixed solution of petroleum ether and ethyl acetate with a volume ratio of 2:1 was used as an eluent, and the mixture was purified by silica gel column chromatography to obtain the final product 10. Finally, it was recrystallized with a mixed solution of dichloromethane and n-hexane, and after suction filtration and drying, it was further purified by temperature gradient sublimation in a vacuum to obtain the final product orange-yellow powder, i.e., a receptor material based on phenanthrene derivatives with a structure of formula 12 (419.8 mg), with a yield of 78%. HRMS (ESI) m / z calcd for: C 54 H 32 N4; (M) + :736.2652, found:736.2620.

[0109] The acceptor material based on phenanthrene derivatives having the structure of Formula 12 obtained in this embodiment was prepared into a pure film by vacuum evaporation. The film was tested at room temperature and irradiated with a 365 nm ultraviolet lamp. Figure 3 The UV-visible light physical property spectrum shows that the material emits sky blue light, the fluorescence peak is 544nm, and the room temperature phosphorescence peak is 560nm. The transient fluorescence spectrum test results are as follows Figure 4 As shown, Figure 4 (a) is the PLQY at room temperature, specifically 49.3%. Figure 4 (b) is the luminescence lifetime at room temperature, specifically 14.5 ms.

[0110] This embodiment adopts the same donor material 1,3-di(9H-carbazole-9-yl)benzene mCBP based on carbazole derivatives as in Embodiment 1, and prepares the organic long afterglow luminescent material mCBP:12 according to the method of Embodiment 1, wherein the mass fraction of the acceptor material based on phenanthrene derivatives is 1 wt%.

[0111] The absorption and emission spectra of the acceptor material based on phenanthrene derivatives and the donor material mCBP and the organic long afterglow luminescent material mCBP:12 composed of the two materials obtained in this embodiment are tested at room temperature. The results are as follows: Figure 8 As shown, compared with the acceptor material based on phenanthrene derivatives and the donor material mCBP of the structure 12, the organic long afterglow luminescent material mCBP: 12 does not present a new absorption peak, indicating that no new excited state transition is formed. At the same time, compared with the donor material mCBP with an emission peak at 371nm and the acceptor material based on phenanthrene derivatives of the structure 12 with an emission peak at 531nm, the emission peak of the organic long afterglow luminescent material mCBP: 12 is at 547nm, and there is an obvious spectral red shift.

[0112] The organic long afterglow luminescent material mCBP:12 obtained in this embodiment was tested for variable temperature spectral transient fluorescence spectroscopy. The results are as follows: Fig. 9 As shown, Fig. 9 (a) is the temperature-dependent fluorescence quantum yield diagram. Fig. 9 (b) is a transient fluorescence spectrum, from which it can be seen that the decay lifetime of the obtained organic long afterglow luminescent material mCBP:12 is 14.5 ms at room temperature 300K, and the PLQY is 87.4%, indicating that it has both thermally activated delayed fluorescence and room temperature phosphorescence luminescence properties.

[0113] In this embodiment, an organic electroluminescent device based on the obtained organic long afterglow luminescent material mCBP:12 is prepared according to the method of embodiment 1. Except for the luminescent layer, the other structures are exactly the same. The luminescent layer is the obtained organic long afterglow luminescent material mCBP:12, and the mass fraction of the acceptor material based on the phenanthrene derivative is 10wt%.

[0114] Fig.10 is the efficiency result of the organic electroluminescent device obtained in this example, wherein: Fig.10 (a) is voltage-brightness-current density, Fig.10 (b) is the brightness-power efficiency-external quantum efficiency, Fig.10 (c) is the wavelength-electroluminescence spectrum, and the performance data shown in Table 2 are statistically obtained. It can be seen that the obtained organic electroluminescent device has excellent luminescence performance.

[0115] Table 2

[0116]

[0117] Example 3

[0118] In this example, afterglow measurement was performed on the organic long afterglow luminescent material mCBP:12 obtained in Example 2.

[0119] 1. Experimental Methods

[0120] Since the long afterglow luminescent material mCBP:12 obtained in Example 2 has a higher fluorescence quantum yield and phosphorescent emission with a long decay lifetime, different afterglow times of the long afterglow luminescent material mCBP:12 can be observed. 0.2 mg of a room temperature phosphorescent acceptor material based on a phenanthrene derivative and 2 mg of a donor material based on a carbazole derivative were mixed and dissolved in 14 mg / mL -1 Then, the organic long afterglow luminescent material mCBP:12 dissolved in PMMA was heated at 70°C for 5 minutes to evaporate its solvent. Finally, the heated organic long afterglow luminescent material mCBP:12 was dropped onto the UESTC transparent glass substrate, ensuring that it was in the "UESTC" area. After that, a camera was used to record the continuous luminescence of the organic long afterglow luminescent material mCBP:12, and a 365nm ultraviolet fluorescent lamp was used as an external excitation light source to observe that the organic long afterglow luminescent material mCBP:12 had different afterglow times.

[0121] 2. Experimental results

[0122] The afterglow measurement results are as follows Fig.11 As shown, the organic long afterglow luminescent material mCBP:12 is yellow-green under sunlight and emits yellow-green light under ultraviolet excitation conditions of 365nm. When the ultraviolet fluorescent lamp is turned off, the organic long afterglow luminescent material mCBP:12 continues to emit light (after turning off the ultraviolet lamp, it continues to emit light as afterglow, and the duration of continued light emission is the afterglow time). Among them, the afterglow color of the organic long afterglow luminescent material mCBP:12 is yellow-green, and the longest afterglow time can reach 1.6s.

[0123] In summary, the organic long afterglow luminescent material provided in this embodiment provides a new reference approach for the construction of new organic long persistent luminescent materials, and has broad application prospects in the fields of sensing detection, information storage, display anti-counterfeiting and decoration.

[0124] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enables any technician in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements that are not different from the text of the claims, or if they include equivalent structural elements that are not substantially different from the text of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. An organic long afterglow luminescent material with enhanced luminescence, characterized in that: Includes donor materials based on carbazole derivatives and acceptor materials based on phenanthrene derivatives; The structure of the receptor material based on phenanthrene derivatives is shown in formula (I): Wherein, R1 and R2 are both cyano groups; L1 and L2 are the same and are selected from dibenzo[b,d]furan, dibenzo[b,d]thiophene, benzophenone, thianthrene, substituted C6, C12 or C18 aryl groups, and substituted heteroaryl groups; The donor material based on carbazole derivatives is one of PVK, TCP, mCP-CN, 26DCzPPy, SBF-Cz, SP-Cz and a material having a structure as shown in formula (II); Here, n represents the number of benzene rings, which is a natural number.

2. The organic long afterglow luminescent material with enhanced luminescence according to claim 1, characterized in that: The mass fraction of the acceptor material based on phenanthrene derivatives is 0.5-10 wt %.

3. The organic long afterglow luminescent material with enhanced luminescence according to claim 1, characterized in that: The receptor material based on phenanthrene derivatives is specifically the material of the following formulas 1 to 21:

4. A method for preparing an organic long afterglow luminescent material with enhanced luminescence, characterized in that: The specific process is: firstly dissolving the donor material based on carbazole derivatives and the acceptor material based on phenanthrene derivatives into an organic solvent, then coating the obtained mixed solution on the surface of the substrate, and heat treating at a temperature of 50 to 70° C. until the organic solvent evaporates; The preparation process of the receptor material based on phenanthrene derivatives comprises the following steps: Step 1: Perform a carbonyl protection reaction on 2,7-dibromophenanthrene-9,10-dione and 2-nitropropane to obtain an intermediate compound C1; Step 2: Performing a carbon-carbon coupling reaction based on the intermediate compound C1, the substituent L1 and a palladium catalyst to obtain an intermediate compound C2; Step 3, performing carbonyl deprotection reaction of the intermediate compound C2 under strong acidic conditions to obtain the intermediate compound C3; Step 4: performing a dehydration condensation reaction on the intermediate compound C3 and 2,3-diamino-2-butenedinitrile to obtain the receptor material based on the phenanthrene derivative; Among them, the intermediate compound C1, the intermediate compound C2 and the intermediate compound C3 are specifically materials of the following structural formula:

5. The method for preparing the organic long afterglow luminescent material with enhanced luminescence according to claim 4, characterized in that: The specific process of step 1 is: Under nitrogen protection, 2,7-dibromophenanthrene-9,10-dione, 2-nitropropane and the first organic solvent are added in sequence to a double-necked flask with a stirring magnet, and the mixture is reacted at a heating temperature of 60 to 80° C. for 18 to 36 hours. A precipitate is precipitated in ice water, and an intermediate compound C1 is obtained after drying; wherein the molar ratio of 2,7-dibromophenanthrene-9,10-dione to 2-nitropropane is 1:1 to 1.

5.

6. The method for preparing the organic long afterglow luminescent material with enhanced luminescence according to claim 4, characterized in that: The specific process of step 2 is: Under nitrogen protection, the intermediate compound C1, the substituent L1, the palladium catalyst and the mixed solvent are added in sequence to a two-necked flask with a stirring magnet, and the reaction is carried out at a heating condition of 80 to 120° C. for 18 to 36 hours. After sequential evaporation, elution, purification, recrystallization, filtration, drying and step-by-step heating sublimation, the intermediate compound C2 is obtained; wherein the molar ratio of the intermediate compound C1, the substituent L1 and the palladium catalyst is 1:1.1 to 1.5:0.1 to 0.

3.

7. The method for preparing the organic long afterglow luminescent material with enhanced luminescence according to claim 4, characterized in that: The specific process of step 3 is: In ice water area and under nitrogen protection, a strong acidic solvent is injected into the intermediate compound C2, and the reaction is first carried out in ice water area for 2 to 4 hours, and then the temperature is raised to room temperature for reaction for 2 to 4 hours. An alkaline solvent is slowly added until the pH is neutral. After filtration and vacuum drying, the intermediate compound C3 is obtained.

8. The method for preparing the organic long afterglow luminescent material with enhanced luminescence according to claim 4, characterized in that: The specific process of step 4 is: Under nitrogen protection, the intermediate compound C3, 2,3-diamino-2-butenedinitrile and acetic acid solution are added in sequence to a double-necked flask with a stirring magnet, and the mixture is reacted at a heating temperature of 110 to 130° C. for 24 to 36 hours. After the reaction, the mixture is extracted, dried, eluted, purified, recrystallized, filtered, dried and step-wise sublimated to obtain the receptor material based on phenanthrene derivatives; wherein the molar ratio of the intermediate compound C3 to 2,3-diamino-2-butenedinitrile is 1:1.0 to 1.

5.

9. Use of the organic long afterglow luminescent material with enhanced luminescence obtained by the preparation method according to any one of claims 4 to 8 in an organic electroluminescent device.

10. An organic electroluminescent device, characterized in that: It comprises an anode, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer and a cathode stacked in sequence; wherein the material of the light-emitting layer is an organic long afterglow light-emitting material with enhanced luminescence obtained by the preparation method described in any one of claims 4 to 8.

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