A method for preparing a hydrogen-bonded organic framework thin film and its application

Abstract

The present invention belongs to the field of materials technology and relates to a preparation method and application of a hydrogen-bonded organic framework thin film. The preparation method of the hydrogen-bonded organic framework thin film includes the preparation of a hydrogen-bonded organic framework material, the preparation of a hydrogen-bonded organic framework ink, and the preparation of a hydrogen-bonded organic framework thin film. The hydrogen-bonded organic framework thin film provided by the present invention exhibits multicolor electrochromic properties from yellow to green to purple under low voltage, and at the same time realizes the dual-band regulation effect in the visible light region and the near-infrared light region. The hydrogen-bonded organic framework thin film in the present invention has a pattern light-emitting display function. Compared with the previous methods for preparing hydrogen-bonded organic framework thin films, the method of the present invention has a simple preparation process, low cost, environmental protection, and is easy to industrialize, and has broad application prospects in patterning, electrochromics, and the optical field.

Description

Technical Field

[0001] The present invention belongs to the technical field of materials, and particularly relates to a preparation method of a hydrogen-bonded organic frameworks (HOFs) thin film and its applications in patterning, electrochromism, and light-emitting display. Background Art

[0002] Hydrogen-bonded organic frameworks (HOFs) are porous crystalline materials self-assembled from organic ligands via intermolecular forces such as hydrogen bonds, π-π, and van der Waals forces, and have shown potential application values in fields such as gas adsorption and separation, fluorescence sensing, and photodynamic therapy. Currently, the main forms of HOFs research are in the form of powders or single crystals. However, in practical applications such as electrochromism and patterned display, it is required to prepare the materials into thin films and devices for application. Preparing hydrogen-bonded organic framework materials into thin films can not only enrich the application forms of HOFs materials but also promote the emergence of new applications of HOFs materials. The currently reported methods for preparing HOFs thin films mainly include solvothermal method, electrophoretic deposition method, photopolymerization method, etc. Among them, the solvothermal method requires some high-pressure-resistant reaction devices, the container is not suitable for expansion, and the solvent conditions are relatively harsh. The template material will dissolve in the solvent under high-temperature conditions, which is not conducive to the preparation of patterning; due to the uneven electric field between two substrates as the substrate increases, the electrophoretic deposition method is not conducive to large-scale film formation; for the photopolymerization method, specific crown functional groups need to be modified on the ligand, the preparation is relatively cumbersome, and the cost is relatively high. Moreover, the spot of the usual xenon lamp is limited, and it is impossible to prepare large-area thin films. Therefore, although these methods can prepare continuous and uniform thin films, large-sized, patterned, continuous, and smooth thin films still cannot be prepared by these methods. Thus, it can be seen that developing a new method for preparing hydrogen-bonded organic framework thin films has important practical and scientific significance.

[0003] Electrochromism (EC) refers to the phenomenon that the color of a material can change stably and reversibly under the action of an external electric field, and it can be applied to fields such as smart windows, anti-glare rearview mirrors, and displays. As an important electrochromic material, HOFs materials have regular and ordered pores and a high specific surface area, and non-electrochromic functional groups do not need to be introduced when constructing the materials, which can shorten the diffusion path of electrolyte ions inside the materials and achieve efficient and rapid color change. However, currently, due to the lack and simplicity of the preparation methods of HOFs thin films, the research on electrochromism has progressed slowly. Developing a new method for preparing HOFs thin films also plays an important role in its electrochromism research.

[0004] In summary, the method for developing novel hydrogen-bonded organic framework thin films is crucial for both the field of HOFs and the field of electrochromics. SUMMARY OF THE INVENTION

[0005] Aiming at the technical problem that large-sized, patterned, continuous and smooth thin films cannot be prepared in the existing applications of hydrogen-bonded organic framework thin films, the present invention provides a method for preparing and applying hydrogen-bonded organic framework thin films. By the method of the present invention, large-area (greater than 840 cm 2 2), patterned (letters, animals) continuous and uniform hydrogen-bonded organic framework thin films are successfully prepared. The prepared thin films exhibit electrochromic properties with multi-color changes in less than 10 s and excellent optical display properties, effectively breaking through the size limitation of HOFs thin films, realizing the multifunctional application of HOFs materials, and being more convenient for industrial production at the same time.

[0006] In order to achieve the above object, the technical solution of the present invention is realized as follows:

[0007] A method for preparing a hydrogen-bonded organic framework thin film, comprising the following steps:

[0008] (1) Preparation of hydrogen-bonded organic framework material: Dissolve an organic ligand in an organic solvent, add water and stir to obtain a hydrogen-bonded organic framework material;

[0009] (2) Preparation of hydrogen-bonded organic framework ink: Disperse the hydrogen-bonded organic framework material obtained in step (1) in a mixed solution of deionized water and an organic solvent to prepare a hydrogen-bonded organic framework ink, and age at room temperature for later use;

[0010] (3) Preparation of hydrogen-bonded organic framework thin film: Clean a conductive substrate and electrostatically spray the hydrogen-bonded organic framework ink obtained in step (2) onto the conductive substrate under the action of an electric field, and after heat treatment, obtain a hydrogen-bonded organic framework thin film.

[0011] A pattern is provided on the hydrogen-bonded organic framework template layer to obtain a patterned hydrogen-bonded organic framework thin film.

[0012] The organic ligand in the step (1) is a tetradentate carboxylic acid ligand, denoted as wherein, R is an aryl group with 6-18 carbon atoms, X is an integer from 0 to 6, and R1 is pyrene or biphenyl.

[0013] The organic ligand in the step (1) is one or more of the compounds represented by the following molecular formulas (I)-(II).

[0014]

[0015] In formula (I), x is an integer multiple of 0-3, and R is the same or different, and is selected from benzene or naphthalene.

[0016]

[0017] In formula (II), x is an integer multiple of 0 - 3, and R is the same or different and is selected from benzene or naphthalene.

[0018] In the step (1), the organic ligand is a tetradentate organic ligand, and the tetradentate organic ligand is one or more of pyrene tetracarboxylic acid, pyrenyltetrabenzoic acid, pyrenyl - quaterphenyl - benzoic acid, pyrenyl - tetranaphthalene - benzoic acid, biphenyl tetracarboxylic acid, and biphenyl tetrabenzoic acid.

[0019] In the step (1), the tetradentate organic ligands are pyrenyltetrabenzoic acid and biphenyl tetrabenzoic acid.

[0020] In the step (1), the organic solvent is one or more of N,N - dimethylformamide, N,N - dimethylacetamide, dimethyl sulfoxide, and ethanol. The volume ratio of the organic solvent to deionized water is 1:(1 - 3) or 2:1, the stirring temperature is 10 - 40°C, and the stirring time is 5 - 30 min.

[0021] In the step (2), the organic solvent is one of ethanol, acetone, and N,N - dimethylformamide. The volume ratio of the organic solvent to deionized water is 1:(1 - 2) or 3:7, the aging time at room temperature is 6 - 12 h, and the concentration of the hydrogen - bonded organic framework ink is 0.05 - 0.1 mg / mL.

[0022] In the step (3), the distance between the conductive substrate and the syringe needle is 8 - 15 cm, the electrostatic spraying voltage is 15 - 25 kV, the electric field voltage is 15 - 25 kV, the heating voltage is 0.3 - 0.6 kV, the electrostatic spraying time is 2 - 10 h, and the heat treatment temperature is 30 - 60°C.

[0023] The area of the hydrogen - bonded organic framework thin film is greater than 840 cm 2 .

[0024] Applications of the hydrogen - bonded organic framework thin film prepared by the above method in patterning, electrochromism, and the optical field.

[0025] The applications of the hydrogen - bonded organic framework thin film prepared by the above method are as follows: When the organic ligand is pyrenyltetrabenzoic acid, immersing the hydrogen - bonded organic framework thin film in an organic electrolyte under a lower voltage drive can exhibit excellent electrochromic performance with multi - color change properties, achieve dual - band regulation in the visible region and the near - infrared region, and simultaneously have a pattern luminescence display function; when the organic ligand is biphenyl tetrabenzoic acid, placing the hydrogen - bonded organic framework thin film under ultraviolet light can exhibit its optical properties.

[0026] When the organic ligand is pyrenyltetracarboxylic acid, the low voltage is below 1.8 V, and the organic electrolyte is tetrabutylammonium hexafluorophosphate, lithium perchlorate polycarbonate solution, etc., preferably tetrabutylammonium hexafluorophosphate. The concentration of the organic electrolyte is 0.1 - 1.5 mol / L, preferably 1.0 mol / L; the multi-color change property is the change from yellow to green and then to purple, and the electrochromic performance is stable for 200 cycles, maintaining 66%.

[0027] The regulated wavelength in the visible region is 550 nm, the modulation range at 550 nm is 58%, the coloring time is 5.6 s, the fading time is 4.4 s, and the coloring efficiency is 185 cm 2 / C; the regulated wavelength in the near-infrared region is 830 nm, the modulation range at 830 nm is 42.5%, the coloring time is 9.2 s, the fading time is 5.1 s, and the coloring efficiency is 100 cm 2 / C; the ultraviolet light wavelengths for the pattern to emit light are 254 nm and 365 nm.

[0028] When the organic ligand is biphenyltetracarboxylic acid, the ultraviolet light wavelength for the hydrogen-bonded organic framework thin film to emit light is 254 nm.

[0029] The present invention has the following beneficial effects:

[0030] 1. Compared with the prior art that uses methods such as solvothermal method, electrophoretic deposition method, and photopolymerization method to prepare hydrogen-bonded organic framework thin films, the film-forming method selected in the method of the present invention is a commercial electrospinning machine. First, it is not restricted by the conditions of the above other methods, and the electrospinning method is carried out under the condition of 40 °C and in air. The conditions are relatively mild and will not damage the template material. The key point is that the HOFs prepared in this paper are all nanorod-shaped materials, which can be well dispersed, and the materials prepared in this way contain certain uncoordinated carboxylic acids, generating certain defects, so that the material surface is charged. Therefore, the material can be used to prepare thin films by electrostatic spraying. Thus, the method of the present invention is more suitable for industrial production.

[0031] 2. When the hydrogen-bonded organic framework thin film prepared by the method of the present invention selects pyrenyltetracarboxylic acid as the organic ligand, it exhibits multi-color electrochromic performance from yellow to green and then to purple under low voltage drive, as well as changes in the visible region and the near-infrared region, realizing the first multi-color research of HOFs materials and the first dual-band regulation effect in the visible light region and the near-infrared light region; at the same time, it also has the function of emitting light and displaying under ultraviolet light of 254 nm and 365 nm.

[0032] 3. When the hydrogen-bonded organic framework thin film prepared by the method of the present invention selects biphenyltetracarboxylic acid as the organic ligand, it has the function of emitting light and displaying under ultraviolet light of 254 nm.

[0033] 4. A pattern is provided on the surface of the hydrogen-bonded organic framework thin film by the method of the present invention, which can be applied to the fields of optical anti-counterfeiting and optical display.

[0034] 5. The method of the present invention selects pyrene tetracarboxylic acid and biphenyl tetracarboxylic acid as organic ligands, and selects rigid and flexible conductive substrates. The area of the hydrogen-bonded organic framework thin film prepared by the electrostatic spraying method is greater than 840 cm 2 , breaking through the limitations of the size and pattern of HOFs thin films prepared by previous methods.

[0035] 6. The method of the present invention has broad application prospects in the fields of patterning, electrochromism, and optics. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0037] Figure 1 Powder X-ray diffraction patterns of the standard HOFs material, the prepared EC-HOFs material, and the EC-HOFs thin film in step (1-3) of Example 1.

[0038] Figure 2 Scanning electron microscope image of the EC-HOFs thin film prepared in step (3) of Example 1.

[0039] Figure 3 Color change diagram of the EC-HOFs thin film prepared in step (3) of Example 1 within the voltage range of 0 - 1.8V.

[0040] Figure 4 Electrochromic performance test diagram of the EC-HOFs thin film prepared in step (3) of Example 1. Among them, Figure a is the cyclic voltammogram (CV) of the EC-HOFs thin film within the voltage range of 0 - 1.8V, with the reference electrode being Ag / Ag + , the counter electrode being a platinum sheet, and the scanning rate being 10 mV / s; Figure b is the ultraviolet-visible-near-infrared spectrum diagram of the EC-HOFs thin film in the initial state, colored state, and faded state; Figures c and d are the kinetic spectra of the EC-HOFs thin film at 550 nm; Figures e and f are the kinetic spectra diagrams of the EC-HOFs thin film at 830 nm.

[0041] Figure 5Kinetic spectrogram of the EC-HOFs film prepared in step (3) of Example 1 and characterization diagram of the EC-HOFs film. Among them, Figure a is the cyclic kinetic spectrogram at 550 nm, and Figure b is the powder X-ray diffraction pattern of the film after cycling.

[0042] Figure 6 Schematic diagram of the hydrogen-bonded organic framework and the patterned hydrogen-bonded organic framework film in step (4) of Example 1. Among them, 1 represents the hydrogen-bonded organic framework film; 2 represents the conductive substrate; 3 represents the pattern template; 4 represents the hydrogen-bonded organic framework film; 5 represents the conductive substrate.

[0043] Figure 7 Letter electrochromic picture of the EC-HOFs film prepared in step (4) of Example 1.

[0044] Figure 8 Animal electrochromic picture of the EC-HOFs film prepared in step (4) of Example 1.

[0045] Figure 9 Optical diagram and spectrogram of the large-area rigid EC-HOFs film prepared in step (5) of Example 1. Among them, Figures a and b are the optical pictures of the large-area rigid EC-HOFs film, and Figure c is the ultraviolet-visible-near-infrared spectrogram of the corresponding points.

[0046] Figure 10 Optical photograph and scanning electron microscope picture of the flexible EC-HOFs film prepared in step (5) of Example 1. Among them, Figure a is the optical photograph of the flexible EC-HOF film, and Figure b is the scanning electron microscope picture of the flexible EC-HOFs film.

[0047] Figure 11 Powder X-ray diffraction patterns of the standard PL-HOFs material and the prepared PL-HOFs film in step (6) of Example 1.

[0048] Figure 12 Scanning electron microscope picture of the PL-HOFs film prepared in step (6) of Example 1.

[0049] Figure 13 Optical photograph (deer) of the PL-HOFs film prepared in step (6) of Example 1 under 254 nm excitation.

[0050] Figure 14 Optical photograph (horse) of the PL-HOFs film prepared in step (6) of Example 1 under 254 nm excitation.

[0051] Figure 15Optical photograph of the EC-HOFs film prepared in step (3) of Example 1 under 365 nm excitation (Deer)

[0052] Figure 16 Optical photograph of the EC-HOFs film prepared in step (3) of Example 1 under 254 nm excitation (Deer). Detailed implementation manners

[0053] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0054] Terms and definitions

[0055] The optical modulation range (ΔT) refers to the difference in transmittance between the bleached state and the colored state of the material.

[0056] The electrochromic response time refers to the time required for a 90% change in the optical modulation range.

[0057] The color efficiency (CE) can be defined by the following formula:

[0058] CE = log(T b / T c ) / Q

[0059] where T b is the transmittance in the bleached state, T c is the transmittance in the colored state, and Q is the electric charge.

[0060] Preparation of hydrogen-bonded organic framework film in Example 1

[0061] (1) Preparation of EC-HOFs film with pyrenyltetracarboxylic acid as the organic ligand

[0062] ⅰ. Preparation of EC-HOFs material with pyrenyltetracarboxylic acid as the organic ligand

[0063] Accurately weigh 60 mg of pyrenyltetracarboxylic acid and dissolve it in 9 mL of a DMF / H2O / EtOH mixed solution (the volume ratio of the organic solvent to deionized water is 1:2) under ultrasonic conditions. Then stir at room temperature for 30 min at a speed of 1500 revolutions per minute, and then centrifuge and wash 3 times with acetone and ethanol respectively. Subsequently, the obtained material is further dispersed in fresh dichloromethane solution and immersed for three days, and the fresh solution is changed every 8 h. Finally, centrifuge and collect and dry in a vacuum drying oven for 8 h to obtain the EC-HOFs material. AsFigure 1 As shown, the prepared EC-HOFs material has the same diffraction peaks as the standard HOFs, indicating that the HOFs material with the same crystal form as the standard EC-HOFs has been successfully prepared.

[0064] ⅱ. Preparation of EC-HOFs ink with pyrene-based tetracarboxylic acid as the organic ligand

[0065] The first step is the cleaning of the substrate. First, the cut conductive glass is placed in fresh acetone, deionized water, and ethanol for ultrasonic cleaning for 15 minutes each, then taken out and dried with high-purity nitrogen for later use.

[0066] The second step is the preparation of EC-HOFs ink. Accurately weigh 2 mg of the above-prepared EC-HOFs material and ultrasonically disperse it in a mixed solvent of deionized water and ethanol (the volume ratio of the organic solvent to deionized water is 1:1) to obtain a uniform ink, and then age it at room temperature for 8 hours for later use.

[0067] ⅲ. Preparation of EC-HOFs thin film with pyrene-based tetracarboxylic acid as the organic ligand

[0068] First, fix the cleaned conductive substrate in the first step to the substrate, then transfer the ink obtained in the second step to a syringe equipped with a plastic liquid tube, and then remove the air bubbles in the syringe by shaking. Then fix the syringe to the electrostatic spraying device and set the distance between the substrate and the needle to 10 cm. Set the spraying voltage to 20 kV, the heating voltage to 0.4 kV, and spray for 8 hours. As Figure 1 shown, the prepared thin film has similar main peaks to the standard EC-HOFs, indicating that its crystal form will not be damaged during the preparation of the thin film. Moreover, as Figure 2 shown, the prepared thin film is continuous and dense and is composed of nanorod-like materials.

[0069] Electrochromic performance test

[0070] Use the above-prepared EC-HOFs thin film as the working electrode, a platinum sheet as the counter electrode, and a silver wire as the reference electrode. The electrolyte is a 1 mol / L solution of tetrabutylammonium hexafluorophosphate in dichloromethane. Perform cyclic voltammetry tests in the voltage range of 0 - 1.8 V at a scan rate of 10 mV / s and find that as Figure 3 shown, there is a multi-color change phenomenon from yellow to green and then to purple, and there is a change in transmittance during the color change process. Among them, the optical modulation range at 550 nm is 58%, the coloring time is 5.6 s, and the fading time is 4.4 s. The optical modulation range at 830 nm is 42.5%, the coloring time is 9.2 s, and the fading time is 5.1 s. Moreover, from Figure 4It can also be seen that the prepared thin film has transmittance variation behaviors in both the visible region and the near-infrared region, indicating that the prepared thin film has dual-band regulation performance in the visible light region and the near-infrared light region. From Figure 5 It can be seen that the prepared thin film has good optical and electrical stability (200 cycles, optical modulation retention of 66%), and the crystal form of the thin film after cycling is consistent with that of the initial thin film, indicating that the prepared thin film has good crystalline stability.

[0071] (2) Preparation of patterned EC-HOFs thin films with pyrenyltetracarboxylic acid as the organic ligand

[0072] After preparing the EC-HOFs thin film with pyrenyltetracarboxylic acid as the organic ligand, a patterned template layer (as shown in Figure 6 ) is prepared on its surface to obtain the patterned EC-HOFs thin film. As shown in Figure 7 and Figure 8 , the prepared thin films with letter and animal patterns show the same color-changing behavior as the EC-HOFs thin film, indicating that EC-HOFs can be applied to patterned color display applications.

[0073] (3) Preparation of large-sized EC-HOFs thin films with pyrenyltetracarboxylic acid as the organic ligand

[0074] The large-sized EC-HOFs thin films are prepared on rigid substrates and flexible substrates respectively.

[0075] A. Preparation of large-sized EC-HOFs thin films with pyrenyltetracarboxylic acid as the organic ligand on a rigid substrate, the steps are as follows:

[0076] ⅰ. Preparation of EC-HOFs material with pyrenyltetracarboxylic acid as the organic ligand: Accurately weigh 60 mg of pyrenyltetracarboxylic acid and dissolve it in 9 mL of DMF / H2O / EtOH mixed solution (the volume ratio of organic solvent to deionized water is 1:2) under ultrasonic conditions, then stir at room temperature for 30 min at a speed of 1500 revolutions per minute, and then centrifuge and wash with acetone and ethanol three times each. Subsequently, the obtained material is further dispersed in fresh dichloromethane solution and immersed for three days, and the fresh solution is changed every 8 h. Finally, centrifuge and collect and dry in a vacuum drying oven for 8 h to obtain the EC-HOFs material.

[0077] ⅱ. Preparation of EC-HOFs ink with pyrenyltetracarboxylic acid as the organic ligand

[0078] The first step is the cleaning of the substrate. First, cut the FTO conductive glass and place it in fresh acetone, deionized water, and ethanol for ultrasonic cleaning for 15 min each, then take it out and dry it with high-purity nitrogen for later use.

[0079] The second step is the preparation of the EC-HOFs ink. Accurately weigh 2 mg of the above-prepared EC-HOFs material and ultrasonically disperse it in a mixed solvent of deionized water and ethanol (the volume ratio of the organic solvent to deionized water is 1:1) to obtain a uniform ink, which is then aged at room temperature for 8 h and kept for use.

[0080] ⅲ. Preparation of the EC-HOFs thin film with pyrenyltetracarboxylic acid as the organic ligand

[0081] First, fix the rigid conductive substrate cleaned in the first step to the substrate, then transfer the ink obtained in the second step to a syringe equipped with a plastic liquid tube, and then remove the air bubbles in the syringe by shaking. Next, fix the syringe to the electrostatic spraying device and set the distance between the substrate and the needle to 10 cm. Set the spraying voltage to 20 kV, the heating voltage to 0.4 kV, and spray for 8 h to obtain the EC-HOFs thin film, and the size of the thin film is greater than 840 cm 2 .

[0082] B. Preparation of the large-size EC-HOFs thin film with pyrenyltetracarboxylic acid as the organic ligand on the flexible substrate, the steps are as follows:

[0083] ⅰ. Preparation of the EC-HOFs material with pyrenyltetracarboxylic acid as the organic ligand

[0084] Accurately weigh 60 mg of pyrenyltetracarboxylic acid and dissolve it in a 9 mL DMF / H2O / EtOH mixed solution (the volume ratio of the organic solvent to deionized water is 1:2) under ultrasonic conditions, then stir at room temperature at a speed of 1500 revolutions per minute for 30 min, and then centrifuge and wash with acetone and ethanol three times each. Subsequently, continue to disperse the obtained material in fresh dichloromethane solution and immerse it for three days, changing the fresh solution every 8 h. Finally, centrifuge and collect and dry it in a vacuum drying oven for 8 h to obtain the EC-HOFs material.

[0085] ⅱ. Preparation of the EC-HOFs ink with pyrenyltetracarboxylic acid as the organic ligand

[0086] The first step is the cleaning of the substrate. First, place the cut ITO conductive glass in fresh acetone, deionized water, and ethanol for ultrasonic cleaning for 15 min each, then take it out and blow it dry with high-purity nitrogen for standby.

[0087] The second step is the preparation of the EC-HOFs ink. Accurately weigh 2 mg of the above-prepared EC-HOFs material and ultrasonically disperse it in a mixed solvent of deionized water and ethanol (the volume ratio of the organic solvent to deionized water is 1:1) to obtain a uniform ink, which is then aged at room temperature for 8 h and kept for use.

[0088] ⅲ. Preparation of the EC-HOFs thin film with pyrenyltetracarboxylic acid as the organic ligand

[0089] First, fix the rigid conductive substrate cleaned in the first step onto the substrate. Then, transfer the ink obtained in the second step into a syringe equipped with a plastic liquid tube. Subsequently, remove the air bubbles in the syringe by shaking. Next, fix the syringe into an electrostatic spraying device and set the distance between the substrate and the needle tip to 10 cm. Set the spraying voltage to 20 kV, the heating voltage to 0.4 kV, and spray for 8 h to obtain the EC-HOFs film.

[0090] As Figure 9 shown, the obtained film is relatively uniform and is further verified by ultraviolet-visible-near-infrared spectroscopy. As Figure 10 shown, the EC-HOFs film prepared on the flexible substrate is easy to transfer and has high flexibility (basically consistent with the substrate). The size of the film is greater than 840 cm 2 .

[0091] (4) Preparation of the PL-HOFs film with biphenyltetracarboxylic acid as the organic ligand

[0092] ⅰ. Preparation of the PL-HOFs material with biphenyltetracarboxylic acid as the organic ligand

[0093] Accurately weigh 60 mg of biphenyltetracarboxylic acid and dissolve it in a 9 mL DMF / H2O / EtOH mixed solution (the volume ratio of the organic solvent to deionized water is 1:2) under ultrasonic conditions. Then, stir at room temperature at a speed of 1500 revolutions per minute for 30 min. Subsequently, centrifuge and wash with acetone and ethanol three times each. Then, continue to disperse the obtained material in fresh dichloromethane solution and immerse it for three days, changing the fresh solution every 8 h. Finally, collect by centrifugation and dry in a vacuum drying oven for 8 h to obtain the PL-HOFs material.

[0094] ⅱ. Preparation of the PL-HOFs ink with biphenyltetracarboxylic acid as the organic ligand

[0095] The first step is the cleaning of the substrate. First, place the cut conductive glass in fresh acetone, deionized water, and ethanol for ultrasonic cleaning for 15 min each. Then, take it out and dry it with high-purity nitrogen for standby.

[0096] The second step is the preparation of the PL-HOFs ink. Accurately weigh 2 mg of the above-prepared PL-HOFs material and ultrasonically disperse it in a mixed solvent of deionized water and ethanol (the volume ratio of the organic solvent to deionized water is 1:1) to obtain a uniform ink. Subsequently, age it at room temperature for 8 h for standby.

[0097] ⅲ. Preparation of the PL-HOFs film with biphenyltetracarboxylic acid as the organic ligand

[0098] First, fix the cleaned conductive substrate in the first step onto the substrate. Then, transfer the ink obtained in the second step into a syringe equipped with a plastic liquid tube. Subsequently, remove the air bubbles in the syringe by shaking. Next, fix the syringe in an electrostatic spraying device and set the distance between the substrate and the needle to 10 cm. Set the spraying voltage to 20 kV, the heating voltage to 0.4 kV, and spray for 8 h to obtain a PL-HOFs thin film.

[0099] Performance test of PL-HOFs thin film with biphenyltetracarboxylic acid as the organic ligand

[0100] As Figure 11 shown, the prepared thin film has the same characteristic diffraction peaks as the standard PL-HOFs material, indicating that the crystal form of HOFs was not damaged during the spraying process. Moreover, as can be seen from Figure 12 shown, the surface of the prepared PL-HOFs thin film is relatively continuous and uniform and is also composed of nanorods.

[0101] (5) Preparation of patterned PL-HOFs thin film with biphenyltetracarboxylic acid as the organic ligand

[0102] After preparing the PL-HOFs thin film with biphenyltetracarboxylic acid as the organic ligand, prepare a patterned template layer on its surface (as Figure 6 shown) to obtain a patterned PL-HOFs thin film. Place the obtained thin film under a 254 nm ultraviolet lamp. By turning the ultraviolet lamp on and off, a patterned luminescent function as shown in Figure 13 and Figure 14 can be displayed.

[0103] Luminescence performance test of EC-HOFs thin film with pyrenyltetracarboxylic acid as the organic ligand

[0104] As Figure 15 and Figure 16 shown, place the prepared PL-HOFs thin film under 365 nm and 254 nm ultraviolet lamps. By turning the ultraviolet lamp on and off, a patterned luminescent function is displayed.

[0105] (6) Preparation of large-sized PL-HOFs thin films on rigid substrates and flexible substrates

[0106] A. Preparation of large-sized PL-HOFs thin film with biphenyltetracarboxylic acid as the organic ligand on a rigid substrate, the steps are as follows:

[0107] ⅰ. Preparation of PL-HOFs material with biphenyltetracarboxylic acid as the organic ligand

[0108] Accurately weigh 60 mg of biphenyltetracarboxylic acid and dissolve it in 9 mL of a DMF / H2O / EtOH mixed solution (the volume ratio of the organic solvent to deionized water is 1:2) under ultrasonic conditions. Then, stir at room temperature for 30 min at a rotation speed of 1500 rpm, and then centrifuge and wash with acetone and ethanol three times each. Subsequently, the obtained material is further dispersed in fresh dichloromethane solution and immersed for three days, with fresh solution replaced every 8 h. Finally, centrifuge and collect, and then dry in a vacuum drying oven for 8 h to obtain the PL-HOFs material.

[0109] ⅱ. Preparation of PL-HOFs ink with biphenyltetracarboxylic acid as the organic ligand

[0110] The first step is the cleaning of the substrate. First, place the cut FTO conductive glass in fresh acetone, deionized water, and ethanol for ultrasonic cleaning for 15 min each, then take it out and blow dry with high-purity nitrogen for standby.

[0111] The second step is the preparation of PL-HOFs ink. Accurately weigh 2 mg of the above-prepared PL-HOFs material and ultrasonically disperse it in a mixed solvent of deionized water and ethanol (the volume ratio of the organic solvent to deionized water is 1:1) to obtain a uniform ink, and then age it at room temperature for 8 h for standby.

[0112] ⅲ. Preparation of PL-HOFs thin film with biphenyltetracarboxylic acid as the organic ligand

[0113] First, fix the rigid conductive substrate cleaned in the first step to the substrate, then transfer the ink obtained in the second step to a syringe equipped with a plastic liquid tube, and then remove the air bubbles in the syringe by shaking. Then, fix the syringe to the electrostatic spraying device and set the distance between the substrate and the needle to 10 cm. Set the spraying voltage to 20 kV, the heating voltage to 0.4 kV, and spray for 8 h to obtain the PL-HOFs thin film, and the size of the thin film is larger than 840 cm 2 。

[0114] B. Preparation of a large-size PL-HOFs thin film with biphenyltetracarboxylic acid as the organic ligand on a flexible substrate, the steps are as follows:

[0115] ⅰ. Preparation of PL-HOFs material with biphenyltetracarboxylic acid as the organic ligand

[0116] Accurately weigh 60 mg of biphenyltetracarboxylic acid and dissolve it in 9 mL of a DMF / H2O / EtOH mixed solution (the volume ratio of the organic solvent to deionized water is 1:2) under ultrasonic conditions. Then, stir at room temperature for 30 min at a rotation speed of 1500 rpm, and then centrifuge and wash with acetone and ethanol three times each. Subsequently, the obtained material is further dispersed in fresh dichloromethane solution and immersed for three days, changing the fresh solution every 8 h. Finally, collect by centrifugation and dry in a vacuum drying oven for 8 h to obtain the PL-HOFs material.

[0117] ⅱ. Preparation of PL-HOFs ink with biphenyltetracarboxylic acid as the organic ligand

[0118] The first step is the cleaning of the substrate. First, place the cut ITO conductive glass in fresh acetone, deionized water, and ethanol for ultrasonic cleaning for 15 min each, then take it out and blow it dry with high-purity nitrogen for standby.

[0119] The second step is the preparation of PL-HOFs ink. Accurately weigh 2 mg of the above-prepared PL-HOFs material and ultrasonically disperse it in a mixed solvent of deionized water and ethanol (the volume ratio of the organic solvent to deionized water is 1:1) to obtain a uniform ink, and then age it at room temperature for 8 h for standby.

[0120] ⅲ. Preparation of PL-HOFs film with biphenyltetracarboxylic acid as the organic ligand: First, fix the rigid conductive substrate cleaned in the first step to the substrate, then transfer the ink obtained in the second step to a syringe equipped with a plastic liquid tube, and then remove the air bubbles in the syringe by shaking. Then, fix the syringe to the electrostatic spraying device and set the distance between the substrate and the needle to 10 cm. Set the spraying voltage to 20 kV, the heating voltage to 0.4 kV, and spray for 8 h to obtain the PL-HOFs film, and the size of the film is larger than 840 cm 2 。

[0121] Example 2

[0122] (1) Preparation of EC-HOFs film with pyrenyltetracarboxylic acid as the organic ligand

[0123] ⅰ. Preparation of EC-HOFs material with pyrenyltetracarboxylic acid as the organic ligand

[0124] Accurately weigh 60 mg of pyrene-based tetracarboxylic acid and dissolve it in 9 mL of a DMF / H2O / EtOH mixed solution (the volume ratio of the organic solvent to deionized water is 1:1) under ultrasonic conditions. Then, stir at 10 °C for 30 min at a rotation speed of 1500 rpm, and then centrifuge and wash with acetone and ethanol three times each. Subsequently, the obtained material is further dispersed in fresh dichloromethane solution and immersed for three days, and the fresh solution is changed every 8 h. Finally, centrifuge and collect, and then dry in a vacuum drying oven for 8 h to obtain the EC-HOFs material.

[0125] ⅱ. Preparation of EC-HOFs ink with pyrene-based tetracarboxylic acid as the organic ligand

[0126] The first step is the cleaning of the substrate. First, place the cut conductive glass in fresh acetone, deionized water, and ethanol for ultrasonic cleaning for 15 min each, then take it out and dry it with high-purity nitrogen for standby.

[0127] The second step is the preparation of EC-HOFs ink. Accurately weigh 2 mg of the above-prepared EC-HOFs material and ultrasonically disperse it in a mixed solvent of deionized water and acetone (the volume ratio of the organic solvent to deionized water is 3:7) to obtain a uniform ink, and then age it at room temperature for 6 h for standby.

[0128] ⅲ. Preparation of EC-HOFs thin film with pyrene-based tetracarboxylic acid as the organic ligand

[0129] First, fix the cleaned conductive substrate in the first step to the substrate, then transfer the ink obtained in the second step to a syringe equipped with a plastic liquid tube, and then remove the air bubbles in the syringe by shaking. Then, fix the syringe to an electrostatic spraying device and set the distance between the substrate and the needle to 8 cm. Set the spraying voltage to 15 kV and the heating voltage to 0.3 kV, and spray for 2 h to obtain the EC-HOFs thin film.

[0130] (2) Preparation of patterned EC-HOFs thin film with pyrene-based tetracarboxylic acid as the organic ligand

[0131] After preparing the EC-HOFs thin film with pyrene-based tetracarboxylic acid as the organic ligand, prepare a patterned template layer on its surface to obtain the patterned EC-HOFs thin film.

[0132] (3) Preparation of large-size EC-HOFs thin film with pyrene-based tetracarboxylic acid as the organic ligand

[0133] The large-size EC-HOF thin film is prepared on a rigid substrate and a flexible substrate.

[0134] A. Preparation of large-size EC-HOFs thin film with pyrene-based tetracarboxylic acid as the organic ligand on a rigid substrate, the steps are as follows:

[0135] ⅰ. Preparation of EC-HOFs materials with pyrene-based tetracarboxylic acid as the organic ligand: Accurately weigh 60 mg of pyrene-based tetracarboxylic acid and dissolve it in a 9 mL mixed solution of DMF / H2O / EtOH under ultrasonic conditions (the volume ratio of organic solvent to deionized water is 1:1). Then stir at 10 °C for 30 min at a rotation speed of 1500 rpm, and then centrifuge and wash it 3 times with acetone and ethanol respectively. Subsequently, the obtained material is further dispersed in fresh dichloromethane solution and immersed for three days, and the fresh solution is changed every 8 h. Finally, centrifuge and collect, and then dry it in a vacuum drying oven for 8 h to obtain the EC-HOFs material.

[0136] ⅱ. Preparation of EC-HOFs ink with pyrene-based tetracarboxylic acid as the organic ligand

[0137] The first step is the cleaning of the substrate. First, place the cut FTO conductive glass in fresh acetone, deionized water, and ethanol for ultrasonic cleaning for 15 min each, then take it out and blow it dry with high-purity nitrogen for later use.

[0138] The second step is the preparation of EC-HOFs ink. Accurately weigh 2 mg of the above-prepared EC-HOFs material and ultrasonically disperse it in a mixed solvent of deionized water and acetone (the volume ratio of organic solvent to deionized water is 3:7) to obtain a uniform ink, and then age it at room temperature for 6 h for later use.

[0139] ⅲ. Preparation of EC-HOFs thin film with pyrene-based tetracarboxylic acid as the organic ligand

[0140] First, fix the rigid conductive substrate cleaned in the first step to the substrate, then transfer the ink obtained in the second step to a syringe equipped with a plastic liquid tube, and then remove the air bubbles in the syringe by shaking. Then fix the syringe to the electrostatic spraying device and set the distance between the substrate and the needle to 8 cm. Set the spraying voltage to 15 kV and the heating voltage to 0.3 kV, and spray for 2 h to obtain the EC-HOFs thin film.

[0141] B. Preparation of large-size EC-HOFs thin film with pyrene-based tetracarboxylic acid as the organic ligand on a flexible substrate, the steps are as follows:

[0142] ⅰ. Preparation of EC-HOFs materials with pyrene-based tetracarboxylic acid as the organic ligand

[0143] Accurately weigh 60 mg of pyrene-based tetracarboxylic acid and dissolve it in 9 mL of a DMF / H2O / EtOH mixed solution (the volume ratio of organic solvent to deionized water is 1:1) under ultrasonic conditions. Then stir at 10 °C for 30 min at a rotation speed of 1500 rpm, and then centrifuge and wash with acetone and ethanol three times each. Subsequently, the obtained material is further dispersed in fresh dichloromethane solution and immersed for three days, with fresh solution replaced every 8 h. Finally, centrifuge and collect, and then dry in a vacuum drying oven for 8 h to obtain the EC-HOFs material.

[0144] ⅱ. Preparation of EC-HOFs ink with pyrene-based tetracarboxylic acid as the organic ligand

[0145] The first step is the cleaning of the substrate. First, place the cut ITO conductive glass in fresh acetone, deionized water, and ethanol for ultrasonic cleaning for 15 min each, then take it out and dry it with high-purity nitrogen for standby.

[0146] The second step is the preparation of EC-HOFs ink. Accurately weigh 2 mg of the above-prepared EC-HOFs material and ultrasonically disperse it in a mixed solvent of deionized water and acetone (the volume ratio of organic solvent to deionized water is 3:7) to obtain a uniform ink, and then age it at room temperature for 6 h for standby.

[0147] ⅲ. Preparation of EC-HOFs thin film with pyrene-based tetracarboxylic acid as the organic ligand

[0148] First, fix the rigid conductive substrate cleaned in the first step to the substrate, then transfer the ink obtained in the second step to a syringe equipped with a plastic liquid tube, and then remove the bubbles in the syringe by shaking. Then fix the syringe to the electrostatic spraying device and set the distance between the substrate and the needle to 8 cm. Set the spraying voltage to 15 kV and the heating voltage to 0.3 kV, and spray for 2 h to obtain the EC-HOFs thin film.

[0149] (4) Preparation of PL-HOFs thin film with biphenyltetracarboxylic acid as the organic ligand

[0150] ⅰ. Preparation of PL-HOFs material with biphenyltetracarboxylic acid as the organic ligand

[0151] Accurately weigh 60 mg of biphenyltetracarboxylic acid and dissolve it in 9 mL of a DMF / H2O / EtOH mixed solution (the volume ratio of organic solvent to deionized water is 1:1) under ultrasonic conditions. Then stir at 10 °C for 30 min at a rotation speed of 1500 rpm, and then centrifuge and wash with acetone and ethanol three times each. Subsequently, the obtained material is further dispersed in fresh dichloromethane solution and immersed for three days, with fresh solution replaced every 8 h. Finally, centrifuge and collect, and then dry in a vacuum drying oven for 8 h to obtain the PL-HOFs material.

[0152] ⅱ. Preparation of PL-HOFs Ink with Biphenyltetracarboxylic Acid as Organic Ligand

[0153] The first step is the cleaning of the substrate. First, the cut conductive glass is placed in fresh acetone, deionized water, and ethanol for ultrasonic cleaning for 15 minutes each, then taken out and dried with high-purity nitrogen for standby.

[0154] The second step is the preparation of PL-HOFs ink. Accurately weigh 2 mg of the above-prepared PL-HOFs material and ultrasonically disperse it in a mixed solvent of deionized water and acetone (the volume ratio of organic solvent to deionized water is 3:7) to obtain a uniform ink, and then age it at room temperature for 6 h for standby.

[0155] ⅲ. Preparation of PL-HOFs Film with Biphenyltetracarboxylic Acid as Organic Ligand

[0156] First, fix the cleaned conductive substrate in the first step to the substrate, then transfer the ink obtained in the second step to a syringe equipped with a plastic liquid tube, and then remove the air bubbles in the syringe by shaking. Then fix the syringe to the electrostatic spraying device and set the distance between the substrate and the needle to 8 cm. Set the spraying voltage to 15 kV, the heating voltage to 0.3 kV, and spray for 2 h to obtain the PL-HOFs film.

[0157] (5) Preparation of Patterned PL-HOFs Film with Biphenyltetracarboxylic Acid as Organic Ligand

[0158] After preparing the PL-HOFs film with biphenyltetracarboxylic acid as the organic ligand, prepare a patterned template layer on its surface to obtain the patterned PL-HOFs film.

[0159] (6) The large-sized PL-HOFs films are prepared on rigid substrates and flexible substrates

[0160] A. The steps for preparing a large-sized PL-HOFs film with biphenyltetracarboxylic acid as the organic ligand on a rigid substrate are as follows:

[0161] ⅰ. Preparation of PL-HOFs Material with Biphenyltetracarboxylic Acid as Organic Ligand

[0162] Accurately weigh 60 mg of biphenyltetracarboxylic acid and dissolve it in 9 mL of DMF / H2O / EtOH mixed solution under ultrasonic conditions (the volume ratio of organic solvent to deionized water is 1:1). Then stir at 10 °C for 30 min at a rotation speed of 1500 rpm, and then centrifuge and wash with acetone and ethanol three times each. Subsequently, continue to disperse the obtained material in fresh dichloromethane solution and immerse it for three days, changing the fresh solution every 8 h. Finally, centrifuge and collect, and then dry it in a vacuum drying oven for 8 h to obtain the PL-HOFs material.

[0163] ⅱ. Preparation of PL-HOFs Ink with Biphenyltetracarboxylic Acid as Organic Ligand

[0164] The first step is the cleaning of the substrate. First, the cut FTO conductive glass is placed in fresh acetone, deionized water, and ethanol and ultrasonically cleaned for 15 minutes each, then taken out and dried with high-purity nitrogen for standby.

[0165] The second step is the preparation of PL-HOFs ink. Accurately weigh 2 mg of the above-prepared PL-HOFs material and ultrasonically disperse it in a mixed solvent of deionized water and acetone (the volume ratio of organic solvent to deionized water is 3:7) to obtain a uniform ink, and then age it at room temperature for 6 h for standby.

[0166] ⅲ. Preparation of PL-HOFs Thin Film with Biphenyltetracarboxylic Acid as Organic Ligand

[0167] First, fix the cleaned conductive substrate in the first step to the substrate, then transfer the ink obtained in the second step to a syringe equipped with a plastic liquid tube, and then remove the bubbles in the syringe by shaking. Then fix the syringe to the electrostatic spraying device and set the distance between the substrate and the needle to 8 cm. Set the spraying voltage to 15 kV, the heating voltage to 0.3 kV, and spray for 2 h to obtain a PL-HOFs thin film, and the size of the thin film is larger than 840 cm 2 。

[0168] B. Preparation of Large-Size PL-HOFs Thin Film with Biphenyltetracarboxylic Acid as Organic Ligand on Flexible Substrate, the steps are as follows:

[0169] ⅰ. Preparation of PL-HOFs Material with Biphenyltetracarboxylic Acid as Organic Ligand

[0170] Accurately weigh 60 mg of biphenyltetracarboxylic acid and dissolve it in 9 mL of DMF / H2O / EtOH mixed solution (the volume ratio of organic solvent to deionized water is 1:1) under ultrasonic conditions, then stir at 10 °C for 30 min at a rotation speed of 1500 rpm, and then centrifuge and wash with acetone and ethanol three times each. Subsequently, the obtained material is further dispersed in fresh dichloromethane solution and immersed for three days, and the fresh solution is changed every 8 h. Finally, centrifuge and collect and dry in a vacuum drying oven for 8 h to obtain the PL-HOFs material.

[0171] ⅱ. Preparation of PL-HOFs Ink with Biphenyltetracarboxylic Acid as Organic Ligand

[0172] The first step is the cleaning of the substrate. First, the cut ITO conductive glass is placed in fresh acetone, deionized water, and ethanol and ultrasonically cleaned for 15 minutes each, then taken out and dried with high-purity nitrogen for standby.

[0173] The second step is the preparation of PL-HOFs ink. Accurately weigh 2 mg of the above-prepared PL-HOFs material, and ultrasonically disperse it in a mixed solvent of deionized water and acetone (the volume ratio of organic solvent to deionized water is 3:7) to obtain a uniform ink. Then, age it at room temperature for 6 h for standby.

[0174] ⅲ. Preparation of PL-HOFs thin film with biphenyltetracarboxylic acid as the organic ligand

[0175] First, fix the cleaned conductive substrate in the first step to the substrate, then transfer the ink obtained in the second step to a syringe equipped with a plastic liquid tube, and then remove the air bubbles in the syringe by shaking. Then, fix the syringe in an electrostatic spraying device, and set the distance between the substrate and the needle to 8 cm. Set the spraying voltage to 15 kV, the heating voltage to 0.3 kV, and spray for 2 h to obtain a PL-HOFs thin film with a size larger than 840 cm 2 .

[0176] Example 3

[0177] (1) Preparation of EC-HOFs thin film with pyrenyltetracarboxylic acid as the organic ligand

[0178] ⅰ. Preparation of EC-HOFs material with pyrenyltetracarboxylic acid as the organic ligand

[0179] Accurately weigh 60 mg of pyrenyltetracarboxylic acid and dissolve it in 9 mL of DMF / H2O / EtOH mixed solution under ultrasonic conditions (the volume ratio of organic solvent to deionized water is 2:1). Then, stir at 40 °C for 5 min at a rotation speed of 1500 rpm, and then centrifuge and wash it with acetone and ethanol three times each. Subsequently, continue to disperse the obtained material in fresh dichloromethane solution and immerse it for three days, changing the fresh solution every 8 h. Finally, centrifuge and collect it, and then dry it in a vacuum drying oven for 8 h to obtain the EC-HOFs material.

[0180] ⅱ. Preparation of EC-HOFs ink with pyrenyltetracarboxylic acid as the organic ligand

[0181] The first step is the cleaning of the substrate. First, place the cut conductive glass in fresh acetone, deionized water, and ethanol for ultrasonic cleaning for 15 min each, then take it out and blow it dry with high-purity nitrogen for standby.

[0182] The second step is the preparation of EC-HOFs ink. Accurately weigh 2 mg of the above-prepared EC-HOFs material, and ultrasonically disperse it in a mixed solvent of deionized water and DMF (the volume ratio of organic solvent to deionized water is 1:2) to obtain a uniform ink. Then, age it at room temperature for 12 h for standby.

[0183] ⅲ. Preparation of EC-HOFs thin films with pyrenyltetracarboxylic acid as organic ligand

[0184] First, fix the cleaned conductive substrate in the first step onto the substrate, then transfer the ink obtained in the second step into a syringe equipped with a plastic liquid tube, and then remove the air bubbles in the syringe by shaking. Next, fix the syringe in an electrostatic spraying device, and set the distance between the substrate and the needle to 15 cm. Set the spraying voltage to 25 kV, the heating voltage to 0.6 kV, and spray for 10 h to obtain the EC-HOFs thin film.

[0185] (2) Preparation of patterned EC-HOFs thin films with pyrenyltetracarboxylic acid as organic ligand

[0186] After preparing the EC-HOFs thin film with pyrenyltetracarboxylic acid as organic ligand, prepare a patterned template layer on its surface to obtain the patterned EC-HOFs thin film.

[0187] (3) Preparation of large-sized EC-HOFs thin films with pyrenyltetracarboxylic acid as organic ligand

[0188] The large-sized EC-HOF thin films are divided into those prepared on rigid substrates and those prepared on flexible substrates.

[0189] A. Preparation of large-sized EC-HOFs thin films with pyrenyltetracarboxylic acid as organic ligand on rigid substrates, the steps are as follows:

[0190] ⅰ. Preparation of EC-HOFs materials with pyrenyltetracarboxylic acid as organic ligand

[0191] Accurately weigh 60 mg of pyrenyltetracarboxylic acid and dissolve it in a 9 mL DMF / H2O / EtOH mixed solution (the volume ratio of organic solvent to deionized water is 2:1) under ultrasonic conditions, then stir at 40 °C for 5 min at a rotation speed of 1500 rpm, and then centrifuge and wash with acetone and ethanol three times each. Subsequently, continue to disperse the obtained material in fresh dichloromethane solution and immerse it for three days, changing the fresh solution every 8 h. Finally, centrifuge and collect and dry in a vacuum drying oven for 8 h to obtain the EC-HOFs material.

[0192] ⅱ. Preparation of EC-HOFs ink with pyrenyltetracarboxylic acid as organic ligand

[0193] The first step is the cleaning of the substrate. First, place the cut FTO conductive glass in fresh acetone, deionized water, and ethanol for ultrasonic cleaning for 15 min each, then take it out and blow it dry with high-purity nitrogen for standby.

[0194] The second step is the preparation of EC-HOFs ink. Accurately weigh 2 mg of the above-prepared EC-HOFs material, and ultrasonically disperse it in a mixed solvent of deionized water and DMF (the volume ratio of organic solvent to deionized water is 1:2) to obtain a uniform ink. Then age it at room temperature for 12 h for standby.

[0195] ⅲ. Preparation of EC-HOFs thin film with pyrenyltetrabenzoic acid as the organic ligand

[0196] First, fix the rigid conductive substrate cleaned in the first step to the substrate, then transfer the ink obtained in the second step to a syringe equipped with a plastic liquid tube, and then remove the air bubbles in the syringe by shaking. Then fix the syringe to the electrostatic spraying device and set the distance between the substrate and the needle to 15 cm. Set the spraying voltage to 25 kV, the heating voltage to 0.6 kV, and spray for 10 h to obtain an EC-HOFs thin film with a size of the thin film greater than 840 cm 2 。

[0197] B. Preparation of large-size EC-HOFs thin film with pyrenyltetrabenzoic acid as the organic ligand on a flexible substrate, the steps are as follows:

[0198] ⅰ. Preparation of EC-HOFs material with pyrenyltetrabenzoic acid as the organic ligand: Accurately weigh 60 mg of pyrenyltetrabenzoic acid and dissolve it in 9 mL of DMF / H2O / EtOH mixed solution under ultrasonic conditions (the volume ratio of organic solvent to deionized water is 2:1), then stir at 40 °C at a speed of 1500 revolutions per minute for 5 min, and then centrifuge and wash it 3 times with acetone and ethanol respectively. Then continue to disperse the obtained material in fresh dichloromethane solution and immerse it for three days, changing the fresh solution every 8 h. Finally, centrifuge and collect it and dry it in a vacuum drying oven for 8 h to obtain the EC-HOFs material.

[0199] ⅱ. Preparation of EC-HOFs ink with pyrenyltetrabenzoic acid as the organic ligand:

[0200] The first step is the cleaning of the substrate. First, place the cut ITO conductive glass in fresh acetone, deionized water, and ethanol for ultrasonic cleaning for 15 min each, then take it out and blow it dry with high-purity nitrogen for standby.

[0201] The second step is the preparation of EC-HOFs ink. Accurately weigh 2 mg of the above-prepared EC-HOFs material, and ultrasonically disperse it in a mixed solvent of deionized water and DMF (the volume ratio of organic solvent to deionized water is 1:2) to obtain a uniform ink. Then age it at room temperature for 10 h for standby.

[0202] ⅲ. Preparation of EC-HOFs thin film with pyrenyltetrabenzoic acid as the organic ligand:

[0203] First, fix the rigid conductive substrate cleaned in the first step to the substrate. Then, transfer the ink obtained in the second step into a syringe equipped with a plastic liquid tube, and then remove the air bubbles in the syringe by shaking. Next, fix the syringe to an electrostatic spraying device, and set the distance between the substrate and the needle to 15 cm. Set the spraying voltage to 25 kV, the heating voltage to 0.6 kV, and spray for 10 h to obtain an EC-HOFs film with a film size larger than 840 cm 2 。

[0204] (4) Preparation of PL-HOFs film with biphenyltetracarboxylic acid as the organic ligand

[0205] ⅰ. Preparation of PL-HOFs material with biphenyltetracarboxylic acid as the organic ligand

[0206] Accurately weigh 60 mg of biphenyltetracarboxylic acid and dissolve it in a 9 mL DMF / H2O / EtOH mixed solution (the volume ratio of organic solvent to deionized water is 2:1) under ultrasonic conditions. Then, stir at 40 °C for 5 min at a rotation speed of 1500 rpm, and then centrifuge and wash with acetone and ethanol three times each. Subsequently, continue to disperse the obtained material in fresh dichloromethane solution and immerse it for three days, changing the fresh solution every 8 h. Finally, centrifuge and collect, and then dry in a vacuum drying oven for 8 h to obtain the PL-HOFs material.

[0207] ⅱ. Preparation of PL-HOFs ink with biphenyltetracarboxylic acid as the organic ligand

[0208] The first step is the cleaning of the substrate. First, place the cut conductive glass in fresh acetone, deionized water, and ethanol for ultrasonic cleaning for 15 min each, then take it out and dry it with high-purity nitrogen for later use.

[0209] The second step is the preparation of PL-HOFs ink. Accurately weigh 2 mg of the above-prepared PL-HOFs material and ultrasonically disperse it in a mixed solvent of deionized water and DMF (the volume ratio of organic solvent to deionized water is 1:2) to obtain a uniform ink, and then age it at room temperature for 10 h for later use.

[0210] ⅲ. Preparation of PL-HOFs film with biphenyltetracarboxylic acid as the organic ligand

[0211] First, fix the conductive substrate cleaned in the first step to the substrate. Then, transfer the ink obtained in the second step into a syringe equipped with a plastic liquid tube, and then remove the air bubbles in the syringe by shaking. Next, fix the syringe to an electrostatic spraying device, and set the distance between the substrate and the needle to 15 cm. Set the spraying voltage to 25 kV, the heating voltage to 0.6 kV, and spray for 10 h to obtain the PL-HOFs film.

[0212] (5) Preparation of Patterned PL-HOFs Films with Biphenyltetracarboxylic Acid as the Organic Ligand

[0213] After preparing the PL-HOFs film with biphenyltetracarboxylic acid as the organic ligand, a patterned template layer is prepared on its surface to obtain the patterned PL-HOFs film.

[0214] (6) Preparation of Large-Size PL-HOFs Films on Rigid Substrates and Flexible Substrates

[0215] A. Preparation of Large-Size PL-HOFs Films with Biphenyltetracarboxylic Acid as the Organic Ligand on Rigid Substrates, the steps are as follows:

[0216] ⅰ. Preparation of PL-HOFs Materials with Biphenyltetracarboxylic Acid as the Organic Ligand

[0217] Accurately weigh 60 mg of biphenyltetracarboxylic acid and dissolve it in 9 mL of a DMF / H2O / EtOH mixed solution (the volume ratio of organic solvent to deionized water is 2:1) under ultrasonic conditions. Then stir at 40 °C for 5 min at a rotation speed of 1500 rpm, and then centrifuge and wash with acetone and ethanol three times each. Subsequently, the obtained material is further dispersed in fresh dichloromethane solution and immersed for three days, changing the fresh solution every 8 h. Finally, centrifuge and collect, and then dry in a vacuum drying oven for 8 h to obtain the PL-HOFs material.

[0218] ⅱ. Preparation of PL-HOFs Inks with Biphenyltetracarboxylic Acid as the Organic Ligand

[0219] The first step is the cleaning of the substrate. First, cut the FTO conductive glass and place it in fresh acetone, deionized water, and ethanol for ultrasonic cleaning for 15 min each, then take it out and blow it dry with high-purity nitrogen for standby.

[0220] The second step is the preparation of PL-HOFs ink. Accurately weigh 2 mg of the above-prepared PL-HOFs material and ultrasonically disperse it in a mixed solvent of deionized water and DMF (the volume ratio of organic solvent to deionized water is 1:2) to obtain a uniform ink, and then age it at room temperature for 10 h for standby.

[0221] ⅲ. Preparation of PL-HOFs Films with Biphenyltetracarboxylic Acid as the Organic Ligand

[0222] First, fix the cleaned conductive substrate in the first step onto the substrate. Then, transfer the ink obtained in the second step into a syringe equipped with a plastic liquid tube. Subsequently, remove the air bubbles in the syringe by shaking. Next, fix the syringe into an electrostatic spraying device, and set the distance between the substrate and the needle tip to 15 cm. Set the spraying voltage to 25 kV, the heating voltage to 0.6 kV, and spray for 10 h to obtain a PL-HOFs film with a film size larger than 840 cm 2 。

[0223] B. Preparation of a large-sized PL-HOFs film with biphenyltetracarboxylic acid as the organic ligand on a flexible substrate, the steps are as follows:

[0224] ⅰ. Preparation of a PL-HOFs material with biphenyltetracarboxylic acid as the organic ligand

[0225] Accurately weigh 60 mg of biphenyltetracarboxylic acid and dissolve it in a 9 mL DMF / H2O / EtOH mixed solution (the volume ratio of the organic solvent to deionized water is 2:1) under ultrasonic conditions. Then, stir at 40 °C for 5 min at a rotation speed of 1500 rpm, and then centrifuge and wash with acetone and ethanol three times each. Subsequently, continue to disperse the obtained material in fresh dichloromethane solution and immerse it for three days, changing the fresh solution every 8 h. Finally, collect by centrifugation and dry in a vacuum drying oven for 8 h to obtain the PL-HOFs material.

[0226] ⅱ. Preparation of a PL-HOFs ink with biphenyltetracarboxylic acid as the organic ligand

[0227] The first step is the cleaning of the substrate. First, place the cut ITO conductive glass in fresh acetone, deionized water, and ethanol for ultrasonic cleaning for 15 min each, then take it out and blow it dry with high-purity nitrogen for standby.

[0228] The second step is the preparation of the PL-HOFs ink. Accurately weigh 2 mg of the above-prepared PL-HOFs material and ultrasonically disperse it in a mixed solvent of deionized water and DMF (the volume ratio of the organic solvent to deionized water is 1:2) to obtain a uniform ink, and then age it at room temperature for 10 h for standby.

[0229] ⅲ. Preparation of a PL-HOFs film with biphenyltetracarboxylic acid as the organic ligand

[0230] First, fix the cleaned conductive substrate in the first step onto the substrate. Then, transfer the ink obtained in the second step into a syringe equipped with a plastic liquid tube. Subsequently, remove the air bubbles in the syringe by shaking. Next, fix the syringe into an electrostatic spraying device, and set the distance between the substrate and the needle tip to 15 cm. Set the spraying voltage to 25 kV, the heating voltage to 0.6 kV, and spray for 10 h to obtain a PL-HOFs film with a film size larger than 840 cm2 。

[0231] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a hydrogen-bonded organic framework thin film, characterized in that, The steps are as follows: (1) Preparation of hydrogen-bonded organic framework material: Dissolve the organic ligand in an organic solvent, add water and stir to obtain the hydrogen-bonded organic framework material; (2) Preparation of hydrogen-bonded organic framework ink: Disperse the hydrogen-bonded organic framework material obtained in step (1) in a mixed solution of deionized water and an organic solvent to prepare the hydrogen-bonded organic framework ink, and age it at room temperature for later use; (3) Preparation of hydrogen-bonded organic framework thin film: Clean the conductive substrate and electrostatically spray the hydrogen-bonded organic framework ink obtained in step (2) onto the conductive substrate under the action of an electric field through a syringe. After heat treatment, a hydrogen-bonded organic framework thin film is obtained; In step (1), the organic ligand is one or more of the compounds represented by the following molecular formulas (I) and (II): In formula (I), x is 0 - 3, and R is the same or different, and is selected from benzene or naphthalene; In formula (II), x is 0 - 3, and R is the same or different, and is selected from benzene or naphthalene.

2. The method for preparing a hydrogen-bonded organic framework thin film according to claim 1, wherein: A pattern can also be provided on the surface of the hydrogen-bonded organic framework thin film to obtain a patterned hydrogen-bonded organic framework thin film.

3. The method for preparing a hydrogen-bonded organic framework thin film according to claim 1, wherein: In step (1), the tetradentate organic ligand is one or more of pyrene tetracarboxylic acid, pyrenyltetrabenzoic acid, pyrenyl-tetraphenyl-benzene-carboxylic acid, pyrenyl-tetra-naphthalene-benzoic acid, biphenyltetracarboxylic acid, and biphenyltetrabenzoic acid.

4. The preparation method of the hydrogen-bonded organic framework thin film according to claim 1, characterized in that: In step (1), the tetradentate organic ligands are pyrenyltetrabenzoic acid and biphenyltetrabenzoic acid.

5. The preparation method of the hydrogen bond organic framework thin film according to claim 1, wherein: In step (1), the organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and ethanol. The volume ratio of the organic solvent to deionized water is 1:(1 - 3) or 2:1, the stirring temperature is 10 - 40 °C, and the stirring time is 5 - 30 min; in step (2), the organic solvent is one of ethanol, acetone, and N,N-dimethylformamide. The volume ratio of the organic solvent to deionized water is 1:(1 - 2) or 3:7, the aging time at room temperature is 6 - 12 h, and the concentration of the hydrogen-bonded organic framework ink is 0.05 - 0.1 mg / mL; in step (3), the distance between the conductive substrate and the syringe needle is 8 - 15 cm, the electrostatic spraying voltage is 15 - 25 kV, the electric field voltage is 15 - 25 kV, the heating voltage is 0.3 - 0.6 kV, and the electrostatic spraying time is 2 - 10 h.

6. The method for preparing a hydrogen-bonded organic framework thin film according to claim 1, characterized in that: The area of the hydrogen-bonded organic framework film is greater than 840 cm 2 .

7. Application of the hydrogen-bonded organic framework thin film prepared by the method according to any one of claims 1 - 6 in patterning, electrochromism, and the optical field.

8. Use of the hydrogen-bonded organic framework thin film according to claim 7, characterized in that: When the organic ligand is pyrenyltetrabenzoic acid, the hydrogen-bonded organic framework thin film has multi-color electrochromic properties and optical display functions; when the organic ligand is biphenyltetrabenzoic acid, the hydrogen-bonded organic framework thin film has optical display functions.

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