Organic long-afterglow material for afterglow emission of biomass carbon dots, preparation method thereof and application of organic long-afterglow material in flexible display

Abstract

The invention discloses an inorganic long-afterglow material for biomass carbon dot afterglow emission, a preparation method of the inorganic long-afterglow material and application of the inorganic long-afterglow material in flexible display, and belongs to the technical field of preparation methods of inorganic long-afterglow materials. According to the method, waste biomass is used as a carbon dot matrix. Biomass carbon dots with different concentrations and boric acid are fully and uniformly mixed according to different proportions, and the uniformly mixed solution is subjected to high-temperature dehydration and recrystallization to generate the glassy state boron oxide B-CDs (B-CDs BA) long afterglow material. The B-CDs (at) BA long afterglow material is added into polydimethylsiloxane (PDMS) to prepare a 36 * 63cm thin film, and the thin film is heated and cured to obtain the flexible transparent display film with afterglow luminescence. The method has the advantages that the method can be used for preparing the long-afterglow flexible film, and the flexible film can be applied to imaging display, is long in afterglow time and has the advantages of being flexible, transparent, large in area, environmentally friendly and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation methods of inorganic long - persistent phosphorescent materials, and specifically to an inorganic long - persistent phosphorescent material with afterglow emission of biomass carbon dots, its preparation method and application in flexible displays. Background Art

[0002] Long - persistent luminescence (LPL) means that the material will emit light for a long time after the excitation light source is turned off. So far, the organic long - persistent phosphorescent materials developed by scientific research personnel have the advantages of long luminescence lifetime, low cost, good processability and biocompatibility. Therefore, they have great application potential in the fields of bioimaging, organic light - emitting diodes, anti - counterfeiting, etc.

[0003] As a new type of zero - dimensional nanomaterial, carbon quantum dots (CDs) have both the advantages of good biocompatibility and rich raw material sources of traditional carbon materials, and unique optical properties. They have potential application prospects in the fields of optoelectronic devices, anti - counterfeiting encryption, bioimaging, solar cells, nanomaterials, etc. CDs have irreplaceable advantages in the fields related to room - temperature phosphorescence (RTP) and thermally activated delayed fluorescence (TADF). Embedding CDs into the matrix effectively reduces the energy difference (ΔEST) of the system, thus promoting the intersystem crossing (ISC) between the excited triplet state and the singlet state, and can fix CDs to reduce their non - radiative decay. However, the CDs currently studied need to be prepared by complex synthetic reactions of organic molecules, and the applications of CDs afterglow materials are generally limited to aspects such as information encryption and anti - counterfeiting. And the currently studied inorganic long - persistent phosphorescent materials of CDs have problems such as short afterglow time, low luminescence efficiency, and easy occurrence of afterglow quenching under high - temperature and low - temperature conditions.

[0004] The Chinese patent application document with publication number CN 111154480A discloses a long - persistent phosphorescent material, its preparation method and application. The long - persistent phosphorescent material is carbon dots compounded into the matrix and in a glassy state, with both fluorescence, delayed fluorescence and phosphorescence properties; this material has a longer lifespan, higher phosphorescence quantum efficiency and better stability, and a metal - free afterglow material has been successfully prepared from heteroatom - free carbon dots, with a lifespan of up to 2682 ms and a phosphorescence quantum efficiency of up to 17.5%. However, the afterglow time of the long - persistent phosphorescent material of this patent is relatively short, so it still needs to be further improved. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to solve the problems of short afterglow time and poor performance of the current carbon quantum dot afterglow materials.

[0006] The present invention solves the above - mentioned technical problems through the following technical means:

[0007] The first aspect of the present invention proposes a preparation method of an inorganic long - persistent phosphorescent material with afterglow emission of biomass carbon dots, including the following steps:

[0008] S1: Thoroughly mix the dried biomass and ethanol solution, conduct hydrothermal reaction, dialyze the supernatant after the reaction and freeze-dry it to obtain biomass carbon quantum dots (B-CDs).

[0009] S2: Configure the B-CDs synthesized in S1 into a solution and mix it thoroughly with boric acid, and perform recrystallization to obtain a long afterglow material of vitreous boron oxide @ CDs (B-CDs@BA).

[0010] Preferably, in S1, the biomass includes one or more of grape skins, melon seed skins, pitaya skins, starfruit skins, oat husks, orange peels, mango peels, and coffee grounds.

[0011] Preferably, in S1, the dosage ratio of the biomass to the ethanol solution is (1 - 10) g : (20 - 100) mL.

[0012] Preferably, in S1, the temperature of the hydrothermal reaction is 140 - 160 °C.

[0013] Preferably, in S2, the mass ratio of B-CDs to boric acid is 1:3000 - 5000.

[0014] Preferably, in S2, the temperature of recrystallization is 140 - 180 °C and the time is 2 - 4 h.

[0015] In the second aspect of the present invention, an inorganic long afterglow material with afterglow emission of the biomass carbon dots prepared by the above preparation method is proposed.

[0016] In the third aspect of the present invention, the application of the above inorganic long afterglow material with afterglow emission of the biomass carbon dots in flexible display is proposed.

[0017] In the fourth aspect of the present invention, a preparation method of a flexible display film is proposed, including the following steps:

[0018] Grind the above inorganic long afterglow material into powder, fully stir it with polydimethylsiloxane (PDMS) under heating conditions, then make the mixed slurry into a film, and heat and cure it to obtain a flexible display film.

[0019] Preferably, the mass ratio of the inorganic long afterglow material to polydimethylsiloxane is 1 - 3:10.

[0020] Preferably, the temperature of the heating condition is 50 - 70 °C.

[0021] Preferably, the temperature of heating and curing is 50 - 70 °C.

[0022] Preferably, the specification of the flexible display film is 36*63 cm.

[0023] The fifth aspect of the present invention provides a flexible display film prepared by the above preparation method.

[0024] The beneficial effects of the present invention are as follows:

[0025] 1. The carbon dots in the present invention are extracted from waste biomass in daily life and doped with non-toxic inorganic boric acid to obtain a stable, environmentally friendly, long afterglow time, and high luminous efficiency inorganic long afterglow material. And the inorganic long afterglow material is uniformly embedded in PDMS to prepare a long afterglow flexible transparent display film. The flexible transparent display film is the core material of a new generation of display technology, with characteristics such as being thin, bendable, and having a high light transmittance, and is widely used in fields such as folding screen mobile phones, transparent vehicle displays, smart wearable devices, AR / VR, etc. The long afterglow flexible transparent film in the present invention has the advantages of good flexibility, foldability, high transparency, clear display, and large-area light-emitting display, and is expected to fill the domestic production capacity gap of high-end display films.

[0026] 2. In the preparation method of the present invention, the process of preparing the long afterglow material by doping waste biomass CDs into inorganic boric acid and performing high-temperature dehydration and recrystallization can induce the biomass carbon dots to emit long afterglow under 255, 365, 405 nm, and white light. This inorganic long afterglow material is applicable to a large number of biomasses and has strong universality.

[0027] 3. The preparation method of the present invention has a simple process, is environmentally friendly and easy to obtain (utilizing waste biomass), does not contain any toxic organic molecules and metals, is environmentally friendly, and the prepared inorganic long afterglow material has stable properties. The method for further obtaining flexible long afterglow display by the method of the present invention is simple and the conditions are mild, which is beneficial to the application of long afterglow materials in various scenarios.

[0028] 4. The inorganic doped long afterglow material prepared by the preparation method of the present invention can be used to prepare a long afterglow flexible film, which can be applied to imaging display and has the advantages of flexibility, transparency, large area, and environmental friendliness. Currently, the existing long afterglow materials cannot simultaneously meet the above four conditions, and this flexible display film can meet the requirements of various professional application scenarios. Description of the Drawings

[0029] Figure 1 Macrophotograph of the LPL of the boric acid-induced grape skin CDs inorganic long afterglow material prepared in Example 1 at room temperature;

[0030] Figure 2 Relevant spectrogram of the boric acid-induced grape skin CDs inorganic long afterglow material prepared in Example 1 at room temperature;

[0031] Figure 3 Macrophotograph of the LPL of the pure boric acid long afterglow material prepared in Comparative Example 1 at room temperature;

[0032] Figure 4 The transparent flexible large-area display effect diagram of the boric acid-induced grape skin CDs inorganic long afterglow material prepared in Example 1;

[0033] Figure 5 The transparent flexible large-area display effect diagram of the boric acid-induced grape skin CDs inorganic long afterglow material prepared in Example 1;

[0034] Figure 6 The macroscopic LPL picture of the boric acid-induced melon seed skin CDs inorganic long afterglow material prepared in Example 2 at room temperature;

[0035] Figure 7 The macroscopic LPL picture of the boric acid-induced pitaya peel CDs inorganic long afterglow material prepared in Example 3 at room temperature;

[0036] Figure 8 The macroscopic LPL picture of the boric acid-induced star fruit peel CDs inorganic long afterglow material prepared in Example 4 at room temperature;

[0037] Figure 9 The macroscopic LPL picture of the boric acid-induced oat shell CDs inorganic long afterglow material prepared in Example 5 at room temperature;

[0038] Figure 10 The macroscopic LPL picture of the boric acid-induced orange peel CDs inorganic long afterglow material prepared in Example 6 at room temperature;

[0039] Figure 11 The macroscopic LPL picture of the boric acid-induced mango peel CDs inorganic long afterglow material prepared in Example 7 at room temperature;

[0040] Figure 12 The macroscopic LPL picture of the boric acid-induced coffee grounds CDs inorganic long afterglow material prepared in Example 8 at room temperature. Detailed implementation manners

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention. Unless otherwise defined, the professional terms used below have the same meaning as understood by those of ordinary skill in the art.

[0042] The test materials, reagents, etc. used in the following examples can be obtained from commercial sources or prepared by well-known methods without special instructions.

[0043] For those without specific technical or conditions indicated in the examples, they can all be carried out according to the techniques or conditions described in the literature in this field or according to the product instructions. Without special instructions, the quantitative tests in the following examples are all set with more than three repeated experiments, and the results are averaged.

[0044] In the following examples, the manufacturers of boric acid and absolute ethanol are both Shanghai Aladdin Biochemical Technology Co., Ltd.; the waste biomass is from Yonghui Supermarket in Changle District, Fuzhou City, Fujian Province, China.

[0045] Example 1:

[0046] An inorganic long afterglow material with afterglow emission of biomass carbon dots includes the following steps:

[0047] S1: The dried waste grape skins and ethanol solution are fully mixed at a ratio of 1 g:30 mL, and after mixing, they are transferred to a high-pressure reaction kettle. The mixed solution is subjected to hydrothermal reaction at 140 °C for 2 h. The supernatant after the hydrothermal reaction is dialyzed and freeze-dried to obtain grape skin carbon quantum dots (GPCDs).

[0048] S2. The GPCDs are configured into a 0.1 mg / mL solution and boric acid are added to 30 mL of distilled water at a ratio of 5 mL:1.5 g and fully mixed. The uniformly mixed solution is dehydrated and recrystallized at 180 °C for 2 h to generate a vitreous boron oxide@CDs (GPCDs@BA) inorganic long afterglow material.

[0049] Using the GPCDs@BA inorganic long afterglow material of this example to prepare a flexible display film includes the following steps:

[0050] The GPCDs@BA long afterglow material is ground into powder, and 1 g is taken and added to 10 g of polydimethylsiloxane (PDMS) under rapid stirring. Stir well under heating at 50 °C. After stirring for 2 hours, the mixed slurry is made into a 36*63 cm film and cured by heating at 70 °C to obtain a flexible display film.

[0051] Example 2:

[0052] An inorganic long afterglow material with afterglow emission of biomass carbon dots includes the following steps:

[0053] S1. The dried waste melon seed skins and ethanol solution are fully mixed at a ratio of 1 g:30 mL, and after mixing, they are transferred to a high-pressure reaction kettle. The mixed solution is subjected to hydrothermal reaction at 160 °C for 1 h. The supernatant after the hydrothermal reaction is dialyzed and freeze-dried to obtain melon seed skin carbon quantum dots (MSCDs).

[0054] S2, MSCDs was prepared into a 0.1 mg / mL solution and boric acid was added into 30 mL of distilled water at a ratio of 5 mL:1 g and mixed thoroughly. The mixed solution was dehydrated and recrystallized at a high temperature of 180 ° C to generate glassy boron oxide @ CDs (MSCDs@BA) inorganic long afterglow material.

[0055] The flexible display film is prepared using the inorganic long afterglow material of this embodiment, and the steps are the same as those in Example 1.

[0056] Example 3:

[0057] An inorganic long afterglow material of biomass carbon dot afterglow emission, comprising the following steps:

[0058] In step S1, sun-dried discarded pitaya peel and an ethanol solution were thoroughly mixed at a ratio of 1 g:30 mL. The mixture was then transferred to an autoclave. The mixed solution was hydrothermally reacted at 140°C for 2 hours. The supernatant after the hydrothermal reaction was dialyzed and freeze-dried to obtain pitaya peel carbon quantum dots (DFCDs).

[0059] S2, DFCDs is prepared into a 0.1 mg / mL solution and boric acid is added into 30 mL of distilled water at a ratio of 5 mL:1.5 g and mixed thoroughly. The mixed solution is dehydrated and recrystallized at a high temperature of 180 ° C to generate a glassy boron oxide @ CDs (DFCDs @ BA) inorganic long afterglow material.

[0060] The flexible display film is prepared using the inorganic long afterglow material of this embodiment, and the steps are the same as those in Example 1.

[0061] Embodiment 4:

[0062] An inorganic long afterglow material of biomass carbon dot afterglow emission, comprising the following steps:

[0063] In step S1, sun-dried discarded carambola peel and an ethanol solution were thoroughly mixed at a ratio of 1 g:30 mL. The mixture was then transferred to an autoclave. The mixed solution was hydrothermally reacted at 140°C for 2 hours. The supernatant after the hydrothermal reaction was dialyzed and freeze-dried to obtain carambola peel carbon quantum dots (CMCDs).

[0064] S2, CMCDs is prepared into a 0.1 mg / mL solution and boric acid is added into 30 mL of distilled water at a ratio of 5 mL:1.5 g and mixed thoroughly. The mixed solution is dehydrated and recrystallized at a high temperature of 180 ° C to generate a glassy boron oxide @ CDs (CMCDs @ BA) inorganic long afterglow material.

[0065] The flexible display film is prepared using the inorganic long afterglow material of this embodiment, and the steps are the same as those in Example 1.

[0066] Example 5:

[0067] An inorganic long afterglow material with afterglow emission of biomass carbon dots, comprising the following steps:

[0068] S1. Add the dried waste oat husks and ethanol solution in a ratio of 1 g:30 mL to 30 mL of distilled water and mix well. After mixing, transfer it to a high-pressure reaction kettle. Carry out hydrothermal reaction on the mixed solution at 140 °C for 2 h. Dialyze the supernatant after the hydrothermal reaction and freeze-dry it to obtain oat husk carbon quantum dots (OHCDs).

[0069] S2. Configure OHCDs into a solution of 0.1 mg / mL and mix well with boric acid in a ratio of 5 mL:0.5 g. Dehydrate and recrystallize the well-mixed solution at a high temperature of 180 °C to generate a glassy boron oxide@CDs (OHCDs@BA) inorganic long afterglow material.

[0070] Use the inorganic long afterglow material of this example to prepare a flexible display film, and the steps are the same as those in Example 1.

[0071] Example 6:

[0072] An inorganic long afterglow material with afterglow emission of biomass carbon dots, comprising the following steps:

[0073] S1. Add the dried waste orange peels and ethanol solution in a ratio of 1 g:30 mL and mix well. After mixing, transfer it to a high-pressure reaction kettle. Carry out hydrothermal reaction on the mixed solution at 140 °C for 2 h. Dialyze the supernatant after the hydrothermal reaction and freeze-dry it to obtain orange peel carbon quantum dots (MOCDs).

[0074] S2. Configure MOCDs into a solution of 0.1 mg / mL and add it to 30 mL of distilled water and mix well with boric acid in a ratio of 5 mL:1.5 g. Dehydrate and recrystallize the well-mixed solution at a high temperature of 180 °C to generate a glassy boron oxide@CDs (MOCDs@BA) inorganic long afterglow material.

[0075] Use the inorganic long afterglow material of this example to prepare a flexible display film, and the steps are the same as those in Example 1.

[0076] Example 7:

[0077] An inorganic long afterglow material with afterglow emission of biomass carbon dots, comprising the following steps:

[0078] S1. Add the dried waste mango peels and ethanol solution in a ratio of 1 g:30 mL and mix well. After mixing, transfer it to a high-pressure reaction kettle. Carry out hydrothermal reaction on the mixed solution at 140 °C for 2 h. Dialyze the supernatant after the hydrothermal reaction and freeze-dry it to obtain mango peel carbon quantum dots (MGCDs).

[0079] S2. Configure the MGCDs into a 0.1 mg / mL solution and add boric acid to 30 mL of distilled water at a ratio of 5 mL:1 g, and mix well. Dehydrate and recrystallize the uniformly mixed solution at 180 °C to produce a glassy boron oxide@CDs (MGCDs@BA) inorganic long afterglow material.

[0080] Use the inorganic long afterglow material of this example to prepare a flexible display film, and the steps are the same as in Example 1.

[0081] Example 8:

[0082] An inorganic long afterglow material with biomass carbon dots afterglow emission, including the following steps:

[0083] S1. Thoroughly mix the dried waste coffee grounds and ethanol solution at a ratio of 1 g:30 mL, and transfer the mixture to a high-pressure reactor after mixing. Carry out a hydrothermal reaction on the mixed solution at 160 °C for 1 h. Dialyze and freeze-dry the supernatant after the hydrothermal reaction to obtain coffee ground carbon quantum dots (CFCDs).

[0084] S2. Configure the CFCDs into a 0.1 mg / mL solution and add boric acid to 30 mL of distilled water at a ratio of 5 mL:1.5 g, and mix well. Dehydrate and recrystallize the uniformly mixed solution at 180 °C to produce a glassy boron oxide@CDs (CFCDs@BA) inorganic long afterglow material.

[0085] Use the inorganic long afterglow material of this example to prepare a flexible display film, and the steps are the same as in Example 1.

[0086] Example 9:

[0087] An inorganic long afterglow material with biomass carbon dots afterglow emission, including the following steps:

[0088] S1: Thoroughly mix the dried waste grape skins and ethanol solution at a ratio of 5 g:60 mL, and transfer the mixture to a high-pressure reactor after mixing. Carry out a hydrothermal reaction on the mixed solution at 150 °C for 1.5 h. Dialyze and freeze-dry the supernatant after the hydrothermal reaction to obtain grape skin carbon quantum dots (GPCDs).

[0089] S2. Configure the GPCDs into a 0.1 mg / mL solution and add boric acid to 30 mL of distilled water at a ratio of 5 mL:2.5 g, and mix well. Dehydrate and recrystallize the uniformly mixed solution at 140 °C for 4 h to produce a glassy boron oxide@CDs (GPCDs@BA) inorganic long afterglow material.

[0090] Use the GPCDs@BA inorganic long afterglow material of this example to prepare a flexible display film, including the following steps:

[0091] The GPCDs@BA long afterglow material was ground into powder, and 3 g was taken and added to 10 g of polydimethylsiloxane (PDMS) under rapid stirring. After stirring thoroughly at 70 °C for 2 hours, the mixed slurry was made into a film of 36*63 cm, and cured by heating at 60 °C to obtain a flexible display film.

[0092] Example 10:

[0093] An inorganic long afterglow material with biomass carbon dots afterglow emission, comprising the following steps:

[0094] S1: The dried waste grape skins and ethanol solution were fully mixed at a ratio of 10 g:100 mL, and after mixing, they were transferred to a high-pressure reaction kettle. The mixed solution was subjected to hydrothermal reaction at 145 °C for 1.5 h. The supernatant after the hydrothermal reaction was dialyzed and freeze-dried to obtain grape skin carbon quantum dots (GPCDs).

[0095] S2, The GPCDs was configured into a 0.1 mg / mL solution and boric acid were added to 30 mL of distilled water at a ratio of 5 mL:2.0 g and mixed thoroughly. The uniformly mixed solution was dehydrated and recrystallized at 160 °C for 3 h to generate a glassy boron oxide@CDs (GPCDs@BA) inorganic long afterglow material.

[0096] Using the GPCDs@BA inorganic long afterglow material of this example to prepare a flexible display film, comprising the following steps:

[0097] The GPCDs@BA long afterglow material was ground into powder, and 2 g was taken and added to 10 g of polydimethylsiloxane (PDMS) under rapid stirring. After stirring thoroughly at 60 °C for 2 hours, the mixed slurry was made into a film of 36*63 cm, and cured by heating at 50 °C to obtain a flexible display film.

[0098] Comparative Example 1:

[0099] 1.5 g of boric acid was added to 30 mL of distilled water and dissolved thoroughly. The dissolved boric acid solution was dehydrated and recrystallized at 180 °C to generate glassy boron oxide.

[0100] The materials prepared in the above Examples 1-8 and Comparative Example 1 were characterized:

[0101] The macroscopic LPL emission pictures of the glassy boron oxide@CDs (GPCDs@BA) inorganic long afterglow material obtained in Example 1 under ultraviolet light of 255 nm, 365 nm and LED white light excitation at room temperature are as Figure 1As shown, when the long afterglow material is excited by a 255 nm light source and the light source is turned off after irradiation for 3 s, the blue afterglow can be maintained for 16 s. When the long afterglow material is excited by a 365 nm light source and the light source is turned off after irradiation for 3 s, the cyan afterglow can be maintained for 7 s. When the long afterglow material is excited by a white light source and the light source is turned off after irradiation for 3 s, the yellow afterglow can be maintained for 4 s. It can be seen that the long afterglow material prepared in this example emits light relatively uniformly and can be excited by white light to emit yellow long afterglow.

[0102] The ultraviolet absorption, fluorescence and phosphorescence spectra of the glassy boron oxide@CDs (GPCDs@BA) inorganic long afterglow material obtained in Example 1 under 255 nm ultraviolet excitation are as Figure 2 shown.

[0103] The macroscopic LPL emission pictures of the blank boric acid afterglow material obtained in Comparative Example 1 under 255 nm and 365 nm ultraviolet light excitation at room temperature are as Figure 3 shown. Under 255 nm and 365 nm light source excitation, the afterglow time of the blank boric acid material is 2 s. Compared with Comparative Example 1, the afterglow time in Example 1 is greatly enhanced by nearly 20 s. And the afterglow time of Comparative Example 1 is short, and there is no afterglow effect in PDMS added, and flexible display cannot be realized.

[0104] The flexible thin film display effect picture (36*63 cm) prepared from the glassy boron oxide@CDs (GPCDs@BA) inorganic long afterglow material obtained in Example 1 is as Figure 4 shown. It can be observed from the figure that the display clarity of the flexible display film is high and it has a very excellent display effect.

[0105] The flexible thin film display effect picture prepared from the glassy boron oxide@CDs (GPCDs@BA) inorganic long afterglow material obtained in Example 1. When observing the flexible display film from the side, it can be seen that the film has a high transparency, and the display effect is still clear under the condition of high transparency as Figure 5 shown.

[0106] The macroscopic LPL emission pictures of the glassy boron oxide@CDs (MSCDs@BA) inorganic long afterglow material obtained in Example 2 under 255 nm, 365 nm ultraviolet light and LED white light excitation at room temperature are as Figure 6 shown. When the long afterglow material is excited by a 255 nm light source and the light source is turned off after irradiation for 3 s, the white afterglow can be maintained for 5 s. When the long afterglow material is excited by a 365 nm light source and the light source is turned off after irradiation for 3 s, the cyan afterglow can be maintained for 7 s. When the long afterglow material is excited by a white light source and the light source is turned off after irradiation for 3 s, the yellow afterglow can be maintained for 3 s. It can be seen that the long afterglow material prepared in this example emits light relatively uniformly and can be excited by white light.

[0107] The macroscopic LPL emission pictures of the vitreous boron oxide@CDs (DFCDs@BA) inorganic long afterglow material obtained in Example 3 under excitation by 255 nm, 365 nm ultraviolet light and LED white light at room temperature are as Figure 7 shown. When the long afterglow material is excited by a 255 nm light source and the light source is turned off after irradiation for 3 s, the white afterglow can be maintained for 7 s. When the long afterglow material is excited by a 365 nm light source and the light source is turned off after irradiation for 3 s, the cyan afterglow can be maintained for 14 s. When the long afterglow material is excited by a white light source and the light source is turned off after irradiation for 3 s, the yellow afterglow can be maintained for 5 s. It can be seen that the long afterglow material prepared in this example emits light relatively uniformly and can be excited by a white light source.

[0108] The macroscopic LPL emission pictures of the vitreous boron oxide@CDs (CMCDs@BA) inorganic long afterglow material obtained in Example 4 under excitation by 255 nm, 365 nm ultraviolet light and LED white light at room temperature are as Figure 8 shown. When the long afterglow material is excited by a 255 nm light source and the light source is turned off after irradiation for 3 s, the white afterglow can be maintained for 7 s. When the long afterglow material is excited by a 365 nm light source and the light source is turned off after irradiation for 3 s, the cyan afterglow can be maintained for 10 s. When the long afterglow material is excited by a white light source and the light source is turned off after irradiation for 3 s, the yellow afterglow can be maintained for 3 s.

[0109] The macroscopic LPL emission pictures of the vitreous boron oxide@CDs (OHCDs@BA) inorganic long afterglow material obtained in Example 5 under excitation by 255 nm, 365 nm ultraviolet light and LED white light at room temperature are as Figure 9 shown. When the long afterglow material is excited by a 255 nm light source and the light source is turned off after irradiation for 3 s, the white afterglow can be maintained for 7 s. When the long afterglow material is excited by a 365 nm light source and the light source is turned off after irradiation for 3 s, the cyan afterglow can be maintained for 9 s. When the long afterglow material is excited by a white light source and the light source is turned off after irradiation for 3 s, the yellow afterglow can be maintained for 2 s. It can be seen that the long afterglow material prepared in this example emits light relatively uniformly and can be excited by a white light source.

[0110] The macroscopic LPL emission pictures of the vitreous boron oxide@CDs (MOCDs@BA) inorganic long afterglow material obtained in Example 6 under excitation by 255 nm, 365 nm ultraviolet light and LED white light at room temperature are as Figure 10 shown. When the long afterglow material is excited by a 255 nm light source and the light source is turned off after irradiation for 3 s, the blue afterglow can be maintained for 10 s. When the long afterglow material is excited by a 365 nm light source and the light source is turned off after irradiation for 3 s, the cyan afterglow can be maintained for 7 s. When the long afterglow material is excited by a white light source and the light source is turned off after irradiation for 3 s, the yellow afterglow can be maintained for 3 s. It can be seen that the long afterglow material prepared in this example emits light relatively uniformly and can be excited by a white light source.

[0111] The macroscopic LPL emission pictures of the vitreous boron oxide@CDs (MGCDs@BA) inorganic long afterglow material obtained in Example 7 under the excitation of 255 nm, 365 nm ultraviolet light and LED white light at room temperature are as follows Figure 11 shown. When the long afterglow material is excited by a 255 nm light source and the light source is turned off after irradiation for 3 s, the white afterglow can be maintained for 9 s. When the long afterglow material is excited by a 365 nm light source and the light source is turned off after irradiation for 3 s, the cyan afterglow can be maintained for 7 s. When the long afterglow material is excited by a white light source and the light source is turned off after irradiation for 3 s, the yellow afterglow can be maintained for 1 s. It can be seen that the long afterglow material prepared in this example emits light more uniformly and can be excited by a white light source.

[0112] The macroscopic LPL emission pictures of the vitreous boron oxide@CDs (CFCDs@BA) inorganic long afterglow material obtained in Example 8 under the excitation of 255 nm, 365 nm ultraviolet light and LED white light at room temperature are as follows Figure 12 shown. When the long afterglow material is excited by a 255 nm light source and the light source is turned off after irradiation for 3 s, the white afterglow can be maintained for 14 s. When the long afterglow material is excited by a 365 nm light source and the light source is turned off after irradiation for 3 s, the cyan afterglow can be maintained for 11 s. When the long afterglow material is excited by a white light source and the light source is turned off after irradiation for 3 s, the yellow afterglow can be maintained for 5 s.

[0113] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of an inorganic long afterglow material with afterglow emission of biomass carbon dots, characterized in that, It includes the following steps: S1: Thoroughly mix dry biomass and an ethanol solution, conduct a hydrothermal reaction, dialyze the supernatant after the reaction and freeze-dry it to obtain biomass carbon quantum dots (B-CDs); S2: Configure the B-CDs synthesized in S1 into a solution, mix it thoroughly with boric acid, and perform recrystallization to obtain a glassy boron oxide@CDs (B-CDs@BA) long afterglow material.

2. The preparation method according to claim 1, characterized in that, In S1, the biomass includes one or more of grape skins, melon seed skins, pitaya skins, star fruit skins, oat husks, orange peels, mango peels, and coffee grounds; the dosage ratio of the biomass to the ethanol solution is (1 - 10) g : (20 - 100) mL.

3. The preparation method according to claim 1, characterized in that, In S1, the temperature of the hydrothermal reaction is 140 - 160 °C.

4. The preparation method according to claim 1, characterized in that, In S2, the mass ratio of B-CDs to boric acid is 1 : 3000 - 5000.

5. The preparation method according to claim 1, characterized in that In S2, the temperature of recrystallization is 140 - 180 °C, and the time is 2 - 4 h.

6. An inorganic long afterglow material prepared by the preparation method according to any one of claims 1 - 5.

7. Application of the inorganic long afterglow material according to claim 6 in flexible display.

8. A method for preparing a flexible display film, comprising the following steps: Grind the inorganic long afterglow material according to claim 6 into powder, stir it thoroughly with polydimethylsiloxane (PDMS) under heating conditions of 50 - 70 °C, then make the mixed slurry into a film, and cure it by heating at 50 - 70 °C to obtain a flexible display film.

9. The preparation method according to claim 8, characterized in that, The mass ratio of the inorganic long afterglow material to polydimethylsiloxane is 1 - 3 :

10.

10. A flexible display film prepared by the preparation method according to any one of claims 8 - 9.

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