Purely organic room temperature phosphorescent material and method of preparation

Abstract

A kind of pure organic room temperature phosphorescent material and preparation method, the pure organic room temperature phosphorescent material includes mass percentage as follows: 10~99 wt% reactive liquid crystal monomer;0.1~5 wt% functional small molecule;1~2 wt% initiator, the preparation method includes the following steps: for the preparation of the pure organic room temperature phosphorescent material described above, including the following steps: 10~99 wt% reactive liquid crystal monomer is heated to melt state;0.1~5 wt% functional small molecule is added and mixed thoroughly;Add initiator to obtain pure organic room temperature phosphorescent material by radical polymerization.The pure organic room temperature phosphorescent material and preparation method, reactive liquid crystal monomer is used as matrix, doped functional small molecule, and has stable phosphorescent emission after polymerization.

Description

Technical Field

[0001] This invention relates to the field of organic light-emitting materials technology, and in particular to a pure organic room temperature phosphorescent material and its preparation method. Background Technology

[0002] In recent years, room-temperature phosphorescent materials have attracted much attention in optoelectronic devices, anti-counterfeiting and encryption fields due to their long lifetime and large Stokes shift. Unlike fluorescence emission, phosphorescence emission requires electrons to undergo an intersystem crossing process from singlet to triplet states and then return from the lowest triplet state (T1) to the ground state (S0) via radiative transition. This process is severely constrained by molecular motion and factors such as water and oxygen quenching. Therefore, materials are usually difficult to achieve phosphorescence emission under room-temperature conditions when exposed to air. At present, although various material systems have been studied, pure organic phosphorescent materials are still difficult to match inorganic compounds and organometallic complexes in terms of phosphorescence lifetime and luminescence efficiency. The specific reasons are: (1) The transition from triplet exciton to ground state is a forbidden transition, and the movement within the molecule can easily cause exciton nonradiative relaxation and quench phosphorescence; (2) Due to the lack of an effective spin-orbit coupling mechanism, the efficiency of organic molecular intersystem crossing (ISC) to form triplet exciton is usually low; (3) Triplet excitons are very easy to react with oxygen or water in the air to generate reactive oxygen species, which in turn quench phosphorescence. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a pure organic room temperature phosphorescent material and its preparation method, which uses a reactive liquid crystal monomer as a matrix, dops functional small molecules, and exhibits stable phosphorescence emission after polymerization.

[0004] This invention provides a pure organic room temperature phosphorescent material, comprising the following components by mass percentage:

[0005] 10~99 wt% reactive liquid crystal monomers;

[0006] 0.1~5 wt% of functional small molecules;

[0007] 1~2 wt% initiator.

[0008] In one embodiment, the reactive liquid crystal monomer includes one or more of RM257 (bis[4-[3-(acryloyloxy)propoxy]benzoic acid](2-methyl-1,4-phenylene) ester), RM82 (1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene), HCM074 (4-[[6-(acryloyloxy)hexyl]oxy]benzoic acid), and 4AB (4-cyanophenyl-4-((6-(acryloyloxy)hexyl)oxy)benzoate).

[0009] In one embodiment, the functional small molecule includes one or more of 2,2′:6′,2′′-tripyridine, 4-(2,4,5-tripyridine-4-phenyl)pyridine, 4-hydroxyquinoline, 4-aminoquinoline, and 4-carboxyquinoline.

[0010] In one embodiment, the initiator includes one or more of AIBN (azobisisobutyronitrile), 4-ABP (4-acryloyloxybenzophenone), and DMPAP (benzoin dimethyl ether).

[0011] In one embodiment, the pure organic room temperature phosphorescent material is used in the production of anti-counterfeiting labels.

[0012] This invention also provides a method for preparing a pure organic room temperature phosphorescent material, used for preparing the pure organic room temperature phosphorescent material described in any one of the above-mentioned methods, comprising the following steps:

[0013] 10~99 wt% of reactive liquid crystal monomers are heated to a molten state;

[0014] Add 0.1~5 wt% of functional small molecules and mix thoroughly;

[0015] Free radical polymerization was carried out by adding an initiator to obtain a pure organic room temperature phosphorescent material.

[0016] In one embodiment, the mold used for free radical polymerization with added initiator is a liquid crystal cell with / without orientation, a capillary tube with different pore sizes, or a polydimethylsiloxane mold.

[0017] The pure organic room temperature phosphorescent material and its preparation method provided by the present invention use reactive liquid crystal monomers as a matrix, doped with functional small molecules, and exhibit stable phosphorescence emission after polymerization. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of the process for preparing pure organic room temperature phosphorescent materials provided by this invention.

[0020] Figure 2 The present invention provides a physical image of a pure organic room temperature phosphorescent material under natural light, wherein a) is the pure organic room temperature phosphorescent material obtained in Example 1, and b) is the pure organic room temperature phosphorescent material obtained in Example 6.

[0021] Figure 3 The delayed phosphorus spectra of the pure organic room temperature phosphorescent material provided by this invention under different excitation light.

[0022] Figure 4 This is the phosphorescence attenuation spectrum of the pure organic room temperature phosphorescent material of the present invention, Example 4.

[0023] Figure 5 This is the mask pattern used to etch information in Embodiment 10 of the present invention.

[0024] Figure 6 This is a schematic diagram of the phosphorescent material of Embodiment 10 of the present invention after the ultraviolet light is removed, wherein (a) is a schematic diagram of phosphorescent emission under ultraviolet light irradiation, (b) is a schematic diagram of phosphorescent emission after the ultraviolet light is turned off for 0.1 seconds, and (c) is a schematic diagram of phosphorescent emission after the ultraviolet light is turned off for 2 seconds.

[0025] Figure 7 These are the fluorescence emission spectra of Examples 1 to 5 of the present invention.

[0026] Figure 8 This is the transient and steady-state emission spectrum of Embodiment 4 of the present invention. Detailed Implementation

[0027] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. Based on the description of the present invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present invention.

[0028] In the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0029] The terms “upper,” “lower,” “left,” “right,” “front,” “back,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use. They are only for the convenience of description and simplification, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0030] The terms “first,” “second,” “third,” etc., are used merely to distinguish elements with similar attributes, not to indicate or imply relative importance or a specific order.

[0031] The terms “include,” “comprising,” or any other variation thereof are intended to cover non-exclusive inclusion, which includes not only the elements listed but also other elements not expressly listed.

[0032] Example 1

[0033] Please see Figure 1 and Figure 7 The pure organic room-temperature phosphorescent material provided by this invention comprises: weighing 20 mg RM257, 80 mg 4AB, 1 mg 2,2′:6′,2′′-tripyridine, and 1 mg photoinitiator DMPAP. The preparation method includes the following steps: placing 20 mg RM257 and 80 mg 4AB in a 4 mL sample vial, heating it to 100°C on a hot plate until completely melted, and then vortexing it for 1 minute to completely dissolve and thoroughly mix it. Weighing 1 mg 2,2′:6′,2′′-tripyridine and adding it to the above molten mixture, stirring thoroughly to disperse it completely. Finally, adding 1 mg of photoinitiator DMPAP, at which point the raw material preparation is complete. The above melt is injected capillarily into a liquid crystal cell with a gap of 30 micrometers and placed on a 70°C hot plate. The sample is then irradiated with a handheld ultraviolet lamp for 15 minutes to completely solidify it. After curing, the polymerized thin film of pure organic room temperature phosphorescent material is carefully removed with a blade. In addition to the liquid crystal cell mentioned above, capillaries with different pore sizes and polydimethylsiloxane molds with regular or irregular shapes such as rectangles, circles, triangles, and trapezoids can also be used. The phosphorescent materials obtained in this way are thin films, fibers, and other three-dimensional shapes.

[0034] like Figure 2 The image shown is a physical representation of the pure organic room-temperature phosphorescent material provided in Example 1 of this invention. It is a thin film exhibiting good light transmittance, or a transparent fiber with a diameter of 100 micrometers. To our knowledge, such highly transparent, large-area phosphorescent thin films or luminescent fiber materials have potential applications in fields such as anti-counterfeiting encryption, waveguide fibers, and all-optical synapses, but their preparation methods have not been reported.

[0035] like Figure 3 The image shows the delayed phosphorus spectrum of the pure organic room-temperature phosphorescent material provided in Embodiment 1 of the present invention under different excitation lights. Yellow-green phosphorescence emission is observed in all samples within a broad excitation spectrum of 300 nm to 400 nm.

[0036] like Figure 4The image shows the phosphorescence decay spectrum of the pure organic room-temperature phosphorescent material provided in Embodiment 1 of the present invention. This type of material can emit phosphorescence for a duration far exceeding conventional levels without the aid of a low-temperature environment, with a phosphorescence lifetime of 329 milliseconds, which is significantly different from the shorter phosphorescence lifetime of traditional organic materials.

[0037] Example 2

[0038] The pure organic room temperature phosphorescent material provided in this embodiment differs from that in Example 1 only in that the functional small molecule is 4-(2,4,5-tripyridine-4-phenyl)pyridine.

[0039] Example 3

[0040] The pure organic room temperature phosphorescent material provided in this embodiment differs from that in Example 1 in that the functional small molecule is 4-hydroxyquinoline.

[0041] Example 4

[0042] Please see Figure 8 The pure organic room temperature phosphorescent material provided in this embodiment differs from that in Example 1 in that the functional small molecule is 4-aminoquinoline.

[0043] Example 5

[0044] The pure organic room temperature phosphorescent material provided in this embodiment differs from that in Example 1 in that the functional small molecule is replaced by 4-carboxyquinoline instead of 2,2′:6′,2′′-tripyridine.

[0045] Example 6

[0046] This embodiment provides a method for preparing a pure organic room temperature phosphorescent material, specifically as follows:

[0047] Weigh 30 mg of RM257 and 70 mg of 4AB into a 4 mL clean sample vial. Heat the vial to 100°C on a hot plate until completely melted, then vortex for 1 minute to ensure complete dissolution and thorough mixing. Weigh 1 mg of 4-hydroxyquinoline and add it to the molten mixture, stirring thoroughly to disperse completely. Finally, add 1 mg of photoinitiator DMPAP. The raw material preparation is now complete. Inject the melt into a 100 μm diameter glass capillary via capillary action and place the vial on a 70°C hot plate. Irradiate the sample with a handheld UV lamp for 15 minutes to allow complete solidification. After solidification, carefully break the glass capillary to remove the polymerized fibrous phosphorescent material.

[0048] Example 7

[0049] This embodiment provides a method for preparing an organic room-temperature phosphorescent material, specifically as follows:

[0050] Weigh 40 mg of RM257 and 60 mg of 4AB into a clean 4 mL sample vial. Heat the vial to 100°C on a hot plate until completely melted, then vortex for 1 minute to ensure complete dissolution and thorough mixing. Weigh 1 mg of 4-(2,4,5-tripyridin-4-ylphenyl)pyridine and add it to the molten mixture, stirring thoroughly to disperse completely. Finally, add 1 mg of photoinitiator DMPAP. The raw material preparation is now complete. Inject the melt into a hollow spherical polydimethylsiloxane mold (5 mm diameter) via capillary action and place it on a 70°C hot plate. Irradiate the sample with a handheld UV lamp for 15 minutes to allow complete curing. After curing, carefully break the glass capillary tube to remove the polymerized spherical phosphorescent material.

[0051] Example 8

[0052] This embodiment provides a method for preparing an organic room temperature phosphorescent material. The difference from Embodiment Six is ​​that BP is used as the initiator and the ultraviolet irradiation time is extended to 4 hours.

[0053] Example 9

[0054] This embodiment provides a method for preparing an organic room temperature phosphorescent material. The difference from Embodiment Six is ​​that the initiator is AIBN, and the UV irradiation time of 15 minutes is replaced by heating at 60 degrees Celsius for 6 hours.

[0055] Example 10

[0056] Please see Figure 5 and Figure 6 This embodiment provides a method for preparing an organic room-temperature phosphorescent material, specifically as follows:

[0057] Weigh 20 mg of RM257 and 80 mg of 4AB into a clean 4 mL sample vial. Heat the vial to 100°C on a hot plate until completely melted, then vortex for 1 minute to ensure complete dissolution and thorough mixing. Weigh 1 mg of 4-aminoquinoline and add it to the molten mixture, stirring thoroughly to disperse completely. Finally, add 1 mg of photoinitiator DMPAP and 1 mg of BP. The raw material preparation is now complete. Inject the melt into a liquid crystal cell with a 30 μm gap using capillary action and place it on a 70°C hot plate. Irradiate the sample with a handheld UV lamp for 15 minutes to allow complete curing. After the first curing step, cover the sample with a patterned mask and continue irradiating with UV lamp for 4 hours to write information. Finally, carefully remove the polymerized thin film of phosphorescent material using a blade.

[0058] like Figure 5 As shown, this is the mask pattern used for etching information in Embodiment 10 of the present invention. Figure 6This is a patterned phosphorescence emission image after ultraviolet light exposure has been removed. This embodiment demonstrates that information can be written using a photomask through a two-step crosslinking method, and the effect is displayed under phosphorescence. This has potential applications in information anti-counterfeiting. Table 1 below compares the performance of this application with common commercial products.

[0059] Table 1

[0060] life Excited state lifetime: 329 milliseconds Excited state lifetime: typically greater than 100 milliseconds Mechanical properties Intrinsic flexibility: good adaptability (e.g., wearable devices). Brittleness: The raw material is fragile; surface coating / encapsulation is required. toxicity Low toxicity: No heavy metal contamination, suitable for biological systems Highly toxic: Contains heavy metals such as cadmium and europium (requires strict packaging); waste requires special treatment (high environmental costs). cost Low cost: widely available raw materials (such as carbazole and quinoline small molecules); simple synthesis process (laboratory cost <10 yuan / gram) High cost: Rare earth raw materials are scarce (iridium is priced at approximately 1000 yuan / gram); the synthesis process is complex (multi-step ligand modification). stability It is not easily quenched by humidity / oxygen and has weak thermal stability. High temperature resistance >300°C (suitable for extreme environments); easily degraded by ultraviolet light (requires light-proof encapsulation).

[0061] As described above, this invention relates to a pure organic room-temperature phosphorescent material and its preparation method. Because it utilizes a liquid crystal matrix that combines chemical polymerization capabilities with localized micro-region rigidity, and promotes the inter-system crossing process from singlet to triplet states through hydrogen bonding interactions between the cyano groups at the liquid crystal ends and the added small molecules, the polymer matrix exhibits superior water and oxygen barrier properties, effectively hindering the quenching of triplet excitons. Different shapes of phosphorescent materials can also be photocured using different molds. Thus, a bulk phosphorescent material is prepared through a simple process using commercially available chemicals.

[0062] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A pure organic room-temperature phosphorescent material, characterized in that, Including the percentage by mass: 97.09~98.04 wt% reactive liquid crystal monomers; 0.97~0.98wt% of functional small molecules; Initiator: 1~1.94 wt%; the sum of the mass percentages of all components is 100%; The reactive liquid crystal monomers include bis[4-[3-(acryloyloxy)propoxy]benzoic acid](2-methyl-1,4-phenylene) ester and 4-cyanophenyl-4-((6-(acryloyloxy)hexyl)oxy)benzoate; The functional small molecules include one of 2,2′:6′,2′′-tripyridine, 4-(2,4,5-tripyridine-4-phenyl)pyridine, 4-hydroxyquinoline, 4-aminoquinoline, and 4-carboxyquinoline.

2. The pure organic room temperature phosphorescent material as described in claim 1, characterized in that, The initiator includes one or more of azobisisobutyronitrile, 4-acryloyloxybenzophenone, and benzoin dimethyl ether.

3. The pure organic room temperature phosphorescent material as described in claim 1, characterized in that, The pure organic room temperature phosphorescent material is used in the production of anti-counterfeiting labels.

4. A method for preparing a pure organic room-temperature phosphorescent material, characterized in that, The preparation of the pure organic room temperature phosphorescent material according to any one of claims 1 to 3 comprises the following steps: The reactive liquid crystal monomer is heated to a molten state; Add functional small molecules and mix thoroughly; Free radical polymerization was carried out by adding an initiator to obtain a pure organic room temperature phosphorescent material.

5. The method for preparing pure organic room temperature phosphorescent materials as described in claim 4, characterized in that, The mold used for free radical polymerization with added initiator can be a liquid crystal cell with or without orientation, a capillary tube with different pore sizes, or a polydimethylsiloxane mold.

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