A method for preparing a high light extraction efficiency scintillator composite film

Abstract

The application discloses a high light extraction efficiency scintillator composite film, and belongs to the technical field of high-energy ray detection.The scintillator composite film comprises a scintillator film and a photonic crystal layer on the scintillator film; wherein the scintillator film is formed by coating a slurry prepared by mixing scintillator powder and a polymer solution on a substrate; and the photonic crystal layer is a three-dimensional periodic structure formed by self-assembly of photonic crystal nanoparticles.The application forms the photonic crystal layer with the three-dimensional periodic structure on the scintillator film by the self-assembly mode, the photonic crystal layer has unique photonic energy band structure and photonic band gap characteristics, effectively diffracts and couples the total internal reflection light in the film, makes the originally "confined" photons successfully escape from the scintillator, improves the light extraction efficiency of the film and reduces the light crosstalk, and realizes the improvement of the device detection sensitivity and the imaging quality.

Description

Technical Field

[0001] This invention belongs to the field of high-energy ray detection technology, specifically involving a method of integrating optical micro / nano structures such as photonic crystals onto the surface of an imaging layer thin film of an optical detector. The aim is to improve the light extraction efficiency of the imaging layer thin film and enhance the macroscopic light output and reduce optical crosstalk of the device by controlling the photon state density. Background Technology

[0002] Indirect X-ray detectors, with their mature fabrication process, controllable manufacturing costs, and superior large-area imaging capabilities, currently hold a dominant technological position in key fields such as medical diagnostics, industrial non-destructive testing, and public safety inspection. This detection technology is based on a composite architecture of a scintillator and a photoelectric sensor: the scintillator layer first absorbs high-energy X-ray photons, converting them into low-energy photons within the visible light range; subsequently, these visible light signals are captured by an amorphous silicon thin-film transistor (a-Si TFT) or a photoelectric sensor based on complementary metal-oxide-semiconductor (CMOS) / charge-coupled device (CCD), and further converted into quantifiable electrical signals. With the increasing demand for digital imaging diagnostics and low-dose radiation imaging, the requirements for the overall performance of detectors are becoming increasingly stringent. Among numerous performance parameters, detection sensitivity and spatial resolution are two core competitive indicators for evaluating detector performance, both directly dependent on the light yield of the scintillator material—that is, the number of visible photons generated per unit of absorbed X-ray energy. Therefore, improving the light yield of the scintillator has become one of the key approaches to optimizing the overall imaging performance of indirect X-ray detectors.

[0003] The demand for high light yield stems from its direct contribution to two key performance characteristics of detectors. Higher light yield means that a single X-ray photon event can generate more visible photons, resulting in a stronger electrical signal at the photodetector. This makes the signal easier to distinguish from noise. Traditional scintillators such as CsI:Tl and Gd2O2S:Tb have been widely used, but they suffer from problems such as long afterglow, high preparation temperatures, or the presence of toxic elements. Furthermore, translating the high intrinsic luminous efficiency of bulk materials into high effective light yield in thin-film morphology remains a significant challenge. In addition, ensuring spatial resolution is mainly determined by the degree of lateral diffusion of scintillating light. In traditional planar thin films, a large number of scintillating photons undergo total internal reflection at an angle greater than the critical angle for total internal reflection at the scintillator-air interface, confining them within the film for waveguide propagation until they are reabsorbed or propagate to the pixel boundary. This "optical crosstalk" phenomenon causes the signal generated by one pixel to diffuse to adjacent pixels, resulting in image blurring and severely limiting the improvement of effective light yield, preventing its theoretical advantages from being translated into practical detector performance. Summary of the Invention

[0004] The purpose of this invention is to address the problems of low light extraction efficiency and low effective light yield in scintillator thin films by proposing a method for preparing high-efficiency scintillator composite thin films. This invention utilizes periodically arranged artificial micro / nano structured photonic crystals to effectively diffract and couple the total internal reflection light of the thin film, thereby breaking the limitations of traditional geometric optics and achieving the performance requirements of "high signal" and "low crosstalk" in the thin film.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A high light extraction efficiency scintillator composite film includes a scintillator film and a photonic crystal layer located on the scintillator film;

[0007] Among them, the scintillator film is formed by coating a slurry prepared from scintillator powder and polymer solution onto a substrate; the photonic crystal layer is a three-dimensional periodic structure formed by the self-assembly of photonic crystal nanoparticles.

[0008] Furthermore, the photonic crystal nanoparticles in the photonic crystal layer are nanoparticles composed of two or more materials with different dielectric constants.

[0009] Furthermore, the photonic crystal layer is an ordered three-dimensional periodic structure with in-plane periodic side-by-side arrangement and out-of-plane ordered stacking.

[0010] Furthermore, the scintillator powder is CsCu2I3 powder, Cs3Cu2I5 powder, Cs3Cu2I5:(0.1-5mol%)K powder, CsPbBr3 powder, CsMnCl3 powder, etc.

[0011] Furthermore, the polymer solution is a PMMA (polymethyl methacrylate) solution, a PS (polystyrene) solution, a PMDS (polydimethylsiloxane) solution, a PDVF (polyvinylidene fluoride) solution, etc.

[0012] Furthermore, the photonic crystal nanoparticles are ZIF-8 (zeolite imidazolium ester framework structure material-8), ZIF-67 (zeolite imidazolium ester framework structure material-67), or ZIF-90 (zeolite imidazolium ester framework structure material-90).

[0013] Furthermore, the ZIF-8 nanoparticles have a size of 100-500 nm, the ZIF-90 nanoparticles have a size of 50-200 nm, and the ZIF-67 nanoparticles have a size of 300-500 nm.

[0014] A method for preparing a high-light-extraction-efficiency scintillator composite thin film includes the following steps:

[0015] Step 1. Preparation of scintillator powder:

[0016] 1.1 Weigh out halide A, halide B, and halide C in a molar ratio of (1-3):1:(0.1-0.5) and mix them in solvent A to obtain mixture B; then add additive C to mixture B, stir and mix evenly, and stir and react at 50-60℃ for 1-2 hours to obtain precursor solution; wherein, the concentration of additive C in precursor solution is 8-10 mol / L;

[0017] 1.2 The precursor solution from step 1.1 is slowly added dropwise to solvent B, and the mixture is stirred vigorously for 1-5 minutes to obtain a crude solution; wherein the stirring rate is 1,000-2,000 rpm.

[0018] 1.3 Separate the crude solution from step 1.2, add detergent to the precipitate, centrifuge a second time, and collect the precipitate;

[0019] 1.4 Drying the precipitate collected in step 1.3 yields scintillator powder;

[0020] Step 2. Preparation of scintillator slurry:

[0021] The polymer powder is mixed with solvent C and heated at 50-60℃ for 1-5 hours until completely dissolved to obtain a polymer solution; then the scintillator powder obtained in step 1.4 is mixed with the polymer solution and heated and stirred at 50-60℃ for 1-2 hours to obtain a scintillator slurry.

[0022] Step 3. Preparation of scintillator thin film:

[0023] Using clean gloves, wipe the surface of the high-transparency optical glass with dish soap to remove as much dirt as possible; then perform ultrasonic cleaning with acetone, deionized water and anhydrous ethanol, with each solution ultrasonic cleaning time being 1-30 minutes; after ultrasonic cleaning, use a nitrogen spray gun to dry the glass surface, and then perform ultraviolet ozone heating treatment for 1-15 minutes.

[0024] The scintillator slurry obtained in step 2 is uniformly coated onto the treated glass substrate and allowed to stand and cure at room temperature or under mild heating conditions (30-40°C) to obtain a scintillator film.

[0025] Step 4. Preparation of photonic crystal solution:

[0026] 4.1 Disperse salt A in solvent D, shake to mix evenly, and prepare a mixed solution D with a concentration of 50-80 mg / mL;

[0027] 4.2 Disperse additive D in solvent D, shake and mix evenly to prepare a mixed solution E with a concentration of 0.10-0.80 mmol / L; add organic matter A to mixed solution E, stir and react at room temperature for 1-2 h to obtain mixed solution F, in which the concentration of organic matter A is 1-5 mol / L;

[0028] 4.3 Mix the mixture F from step 4.2 with the mixture D from step 4.1 and stir slowly for 1-30 seconds to obtain a crude solution; wherein the volume ratio of mixture D to mixture F is 1:(0.5-1.5).

[0029] 4.4 Disperse additive D in solvent D, shake and mix evenly to prepare a mixed solution G with a concentration of 0.10-0.50 mg / mL; separate the crude solution from step 4.3, add mixed solution G to the separated precipitate, centrifuge twice, and collect the precipitate;

[0030] 4.5 Disperse the precipitate obtained in step 4.4 in the mixed solution G to obtain the photonic crystal solution; wherein the concentration of the photonic crystal solution is 10-50 mg / mL;

[0031] Step 5. Preparation of high-efficiency scintillator composite film:

[0032] Take 0.1-0.5 mL of the photonic crystal solution from step 4.5 and uniformly coat it onto the surface of the scintillator film obtained in step 3. After completion, let the film stand and cure at room temperature or under mild heating conditions (30-40°C) to obtain the high light extraction efficiency scintillator composite film; wherein, the thickness of the photonic crystal layer is 0.05-0.25 mm.

[0033] Furthermore, in step 1.1, halide A is formamidine hydroiodide (FAI), cesium iodide (CsI), formamidine hydrobromide (FABr), or cesium bromide (CsBr), etc.; halide B is lead iodide (PbI2), lead bromide (PbBr2), cuprous iodide (CuI), or cuprous bromide (CuBr), etc.; halide C is potassium iodide (KI), zinc iodide (ZnI2), etc.; solvent A is ethanol, isopropanol (IPA), or N,N-dimethylformamide (DMF), etc.; additive C is oleic acid (OA), oleylamine (OAm), hypophosphorous acid (H3PO2), etc.

[0034] Furthermore, in step 1.2, solvent B is ethyl acetate, methyl acetate, chlorobenzene, methanol, ethanol, toluene, chloroform, acetonitrile, etc.

[0035] Furthermore, in step 1.3, the separation is centrifugal separation, the centrifugation speed is 5,000-10,000 rpm, and the centrifugation time is 1-10 min; the detergent is cyclohexane, chlorobenzene, methanol, ethanol, toluene, chloroform, etc.

[0036] Furthermore, in step 2, solvent C is chlorobenzene, toluene, chloroform, etc.

[0037] Furthermore, in step 2, the polymer is PMMA (polymethyl methacrylate), PS (polystyrene), PMDS (polydimethylsiloxane), PDVF (polyvinylidene fluoride), etc.

[0038] Furthermore, in the scintillator slurry described in step 2, the mass percentage of scintillator powder is 50-99 wt%, and the mass percentage of polymer is 1-50 wt%.

[0039] Furthermore, in step 2, the scintillator powder is CsCu2I3 powder, Cs3Cu2I5 powder, Cs3Cu2I5:(0.1-5mol%)K powder, CsPbBr3 powder, CsMnCl3 powder, etc.

[0040] Furthermore, in step 4.1, salt A is zinc acetate dihydrate (Zn(CH3COO)2·2H2O), magnesium acetate dihydrate (Mg(CH3COO)2·2H2O), manganese acetate dihydrate (Mn(CH3COO)2·2H2O), copper acetate dihydrate (Cu(CH3COO)2·2H2O), etc.; solvent D is ethanol, isopropanol (IPA), ultrapure water (UP water), or N,N-dimethylformamide (DMF), etc.

[0041] Furthermore, in step 4.2, additive D is hexadecyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), polyvinylpyrrolidone (PVP), 3-aminopropyltriethoxysilane (APTES), etc.; organic compound A is 2-methylimidazole (2-MI), benzimidazole (BIM), triethanolamine (TEOA), etc.

[0042] Furthermore, in step 4.3, the stirring speed is 200-500 rpm.

[0043] Furthermore, in step 4.4, the separation is centrifugal separation, with a centrifugation speed of 10,000-11,000 rpm and a centrifugation time of 8-10 min.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0045] 1. The present invention provides a high light extraction efficiency scintillator composite thin film, on which a three-dimensional periodic photonic crystal layer is formed by self-assembly on the scintillator thin film. The photonic bandgap of the crystal overlaps with the photonic modes trapped in the thin film, redistributing the energy of the photons to the radiation modes that can escape the thin film. Due to its unique photonic band structure and photonic bandgap characteristics, the total internal reflection light in the thin film is effectively diffracted and coupled, allowing the originally "trapped" photons to successfully escape the scintillator, thereby improving the light extraction efficiency of the thin film and reducing optical crosstalk, thus improving the detection sensitivity and imaging quality of the device.

[0046] 2. This invention provides a method for preparing a high-light-extraction-efficiency scintillator composite thin film. Among the many synthetic routes for optical micro / nanostructure materials, solvent synthesis stands out due to its precise control over crystal nucleation and growth kinetics. Through solvation interactions between solvent molecules and metal precursors and organic ligands, it effectively regulates the solubility and reactivity of reaction components, thereby achieving directional assembly under mild conditions. Achieving precise and reproducible control over the size of photonic crystal nanoparticles is a core prerequisite for their transition from basic research to advanced functional applications such as sensing, optical coatings, and photonic devices. Attached Figure Description

[0047] Figure 1 This is a schematic diagram illustrating the formation of the ZIF-8 nanoparticles of the present invention;

[0048] Figure 2 This is a schematic diagram of the structure of the ZIF-8 photonic crystal modified Cs3Cu2I5:K@PS scintillator film of the present invention;

[0049] Figure 3 Scanning electron microscope (SEM) images of ZIF-8 nanoparticles from Examples 1 (276 nm PhCs), 2 (124 nm PhCs), 3 (101 nm PhCs), and 4 (87 nm PhCs);

[0050] Figure 4 The signal comparison diagrams are for Example 1 (276 nm PhCs), Example 2 (124 nm PhCs), Example 3 (101 nm PhCs), Example 4 (87 nm PhCs), and the comparative example scintillator films;

[0051] Figure 5 The modulation transfer function (MTF) plots are for Example 1 (276 nm PhCs), Example 2 (124 nm PhCs), Example 3 (101 nm PhCs), Example 4 (87 nm PhCs), and the comparative scintillator thin films.

[0052] Figure 6The radiative emission (RL) spectra of the thin films of Example 1 (276 nm PhCs), Example 2 (124 nm PhCs), Example 3 (101 nm PhCs), Example 4 (87 nm PhCs), and the comparative scintillator film are shown. Detailed Implementation

[0053] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0054] A high-efficiency scintillator composite film includes a scintillator film and a photonic crystal layer on top of the scintillator film. The scintillator film is formed by coating a slurry prepared from scintillator powder and a polymer solution onto a substrate. The photonic crystal layer is a three-dimensional ordered superlattice constructed through a self-assembly method. Its basic structural unit is nanoparticles, which are composite nanomaterials composed of organic ligands and metal ions with different dielectric constants. During self-assembly, these nanoparticles spontaneously organize in space, forming a long-range ordered three-dimensional structure that is periodically arranged side-by-side in the in-plane direction and orderly stacked layer by layer in the out-of-plane direction.

[0055] Example 1 Experimental Group (276 nm PhCs) Scintillator Composite Thin Film

[0056] Step 1. Prepare a 15 mL sample vial, clean it with deionized water and ethanol, dry it, and place a clean magnetic oscillator inside. Weigh 1.1691 g CsI, 0.5713 g CuI, and 24.9 mg KI into the sample vial, add 12 mL DMF as solvent and 200 μL H3PO2 as additive, place the sample vial on a heated stirring table at room temperature, and heat and stir at 60°C and 600 rpm for 0.5-1 h until the solution becomes clear and transparent with no visible particles, thus obtaining the precursor solution.

[0057] Step 2: Prepare a 15 mL open reaction vessel (e.g., a beaker), clean it with deionized water and ethanol, dry it, and place a clean magnetic stir bar inside. Add 10 mL of antisolvent (e.g., toluene) to the vessel, place it on a magnetic stirrer, and begin vigorous stirring. Using a syringe or pipette, slowly inject 1 mL of the precursor solution from Step 1 into the vigorously stirred antisolvent. Upon mixing, the solution immediately becomes cloudy, indicating that Cs3Cu2I5:K microcrystals have formed, yielding a crude Cs3Cu2I5:K solution.

[0058] Step 3: Centrifuge the crude solution from Step 2 at 8,000 rpm for 5 min to precipitate the microcrystals. Discard the supernatant, add 5 mL of fresh antisolvent (such as toluene), shake thoroughly, and centrifuge at 8,000 rpm for 5 min. Repeat this process 1-2 times to wash away impurities. Briefly dry the final precipitate at a low temperature (such as 30-40℃), or directly redisperse it in a stable nonpolar solvent (such as toluene) to obtain the Cs3Cu2I5:K microcrystalline material.

[0059] Step 4: Prepare a 15 mL sample vial, clean it with deionized water and ethanol, dry it, and place a clean magnetic oscillator inside. Weigh 0.1 g of PS into the sample vial, add 0.5 mL of toluene, and heat and stir at 60°C and 300 rpm for 1-3 hours until the solution becomes clear and transparent, obtaining a polymer PS solution. Weigh 0.326 g of Cs3Cu2I5:K powder from Step 3 and add it to the PS solution. Heat and stir at 60°C and 300 rpm until the solution is uniformly mixed, obtaining a Cs3Cu2I5:K slurry.

[0060] Step 5: Using clean gloves, wipe the high-transparency optical glass with dish soap to remove as much dirt as possible; then perform ultrasonic cleaning with acetone, deionized water, and anhydrous ethanol respectively, for 1-30 minutes for each solution; after ultrasonic cleaning, dry the glass surface with a nitrogen spray gun, followed by 1-15 minutes of ultraviolet ozone heating treatment; place the prepared slurry on a heated stirring table and heat and stir at 60°C and 300 rpm to ensure good slurry dispersion; use an electric squeegee in a fume hood with a stable air velocity of 1.2 m / s. Before operation, confirm that the power supply and air circuit of the electric squeegee are normal, and conduct a no-load test run to verify that all systems of the equipment are in normal working condition. Install the squeegee onto the squeegee holder of the electric squeegee and ensure that the squeegee is firmly installed. Smoothly attach the treated substrate to the vacuum adsorption platform, start the vacuum pump to fix the substrate, and confirm that the substrate surface is flat. Adjust the height in micrometers by selecting standard shims of different thicknesses (0.10-1.00 mm). Apply the prepared slurry evenly to the substrate, and set the scraping parameters on the electric scraper's operating interface (travel speed: 1-10 mm / s, travel distance: 0-150 mm, travel acceleration: 1-10 mm / s). 2 Start the equipment at a scraper height of 0.20 mm, a travel speed of 1 mm / s, a travel distance of 30 mm, and a travel speed of 10 mm / s. 2Under the propulsion acceleration, the doctor blade moves unidirectionally at a constant speed to coat the substrate surface. A uniform wet film can be formed on the substrate through a single coat. After completion, the film is allowed to cure at room temperature or under mild heating conditions (30-40°C) to finally obtain a Cs3Cu2I5:K@PS film.

[0061] Step 6: Prepare a 6 mL sample vial, clean it with deionized water and ethanol, dry it, and place a clean magnetic spool inside. Weigh 0.3 g of Zn(CH3COO)2·2H2O into the sample vial, and add 5 mL of UP water as a solvent. Place the sample vial on a stirring table at room temperature and stir until the solution becomes clear, transparent, and free of any visible particles, thus obtaining the central ion solution.

[0062] Step 7: Prepare a 15 mL sample vial, clean it with deionized water and ethanol, dry it, and place a clean magnetic oscillator inside. Weigh 0.91 mg CTAB and 1.1166 g 2-methylimidazole into the sample vial, and add 5 mL of UP water as a solvent. Place the sample vial on a stirring table at room temperature and stir for 2 hours until the solution becomes clear, transparent, and free of any visible particles. Add 5 mL of the central ion solution from Step 6 to the sample vial and react thoroughly at a stirring rate of 300 rpm for 20 seconds to obtain a crude solution.

[0063] Step 8: Centrifuge the crude solution from Step 7 at 10,000 rpm for 10 min to precipitate the ZIF-8 nanoparticles. Discard the supernatant, add 5 mL of fresh 0.25 mg / mL CTAB solution, shake thoroughly, and centrifuge at 11,000 rpm for 10 min. Repeat this process 1-2 times to wash away impurities. Redisperse the final precipitate directly in 0.25 mg / mL CTAB solution to obtain the ZIF-8 nanoparticle solution.

[0064] Step 9: Use the electric squeegee in a fume hood with a stable wind speed of 1.2 m / s. Before operation, confirm that the power supply and air circuit of the electric squeegee are connected normally, and conduct a no-load test run to verify that all systems of the equipment are in normal working condition. Install the squeegee onto the squeegee holder of the electric squeegee and ensure that the squeegee is firmly installed. Smoothly attach the Cs3Cu2I5:K@PS thin film-glass substrate from Step 5 onto the vacuum adsorption platform, start the vacuum pump to fix the substrate, and confirm that the substrate surface is flat. Adjust the height in micrometers by selecting standard shims of different thicknesses (0.10-1.00 mm). Uniformly coat the ZIF-8 photonic crystal solution from Step 8 onto the surface of the Cs3Cu2I5:K@PS thin film, and set the squeegee parameters (travel speed: 1-10 mm / s, travel distance: 0-150 mm, travel acceleration: 1-10 mm / s) on the electric squeegee operation interface. 2 Start the equipment at a scraper height of 0.1 mm, a travel speed of 1 mm / s, a travel distance of 30 mm, and a speed of 10 mm / s. 2 Under the propulsion acceleration, the doctor blade moves unidirectionally at a constant speed to coat the film surface. A uniform ZIF-8 photonic crystal layer can be formed on the film through a single coating step. After completion, the film is cured at room temperature or under mild heating conditions (30-40°C) to finally obtain a Cs3Cu2I5:K@PS (ZIF-8 PhCs) composite film.

[0065] Example 2 Experimental Group (124 nm PhCs) Scintillator Composite Thin Film

[0066] The difference from Example 1 is that 0.98 mg of CTAB is weighed in step 7; the rest of the steps are exactly the same as in Example 1.

[0067] Example 3 Experimental Group (101 nm PhCs) Scintillator Composite Thin Film

[0068] The difference from Example 1 is that 1.05 mg of CTAB is weighed in step 7; the rest of the steps are exactly the same as in Example 1.

[0069] Example 4 Experimental Group (87 nm PhCs) Scintillator Composite Thin Film

[0070] The difference from Example 1 is that 1.16 mg of CTAB is weighed in step 7; the rest of the steps are exactly the same as in Example 1.

[0071] Comparative Example

[0072] The difference from Example 1 is that the preparation and coating of the ZIF-8 nanoparticle solution are not performed; the remaining steps are exactly the same as in Example 1.

[0073] The above steps describe in detail the preparation process of each embodiment.

[0074] like Figure 1 This diagram illustrates the formation of the ZIF-8 nanoparticles involved in this invention. ZIF-8, as a paradigm material in MOFs, is essentially a three-dimensional extended network formed by the coordination self-assembly of divalent zinc ions and 2-methylimidazole. At the atomic scale, each Zn... 2+ The center forms tetrahedral coordination nodes with four 2-methylimidazolium ligands, while each 2-methylimidazolium molecule acts as a linear bridging ligand connecting adjacent metal nodes. This specific connection method gives it a sodalite topology similar to that of natural zeolites. Spatially, this topology is represented by truncated octahedral cages composed of imidazolium ester segments as basic structural units. These polyhedral units are tightly packed in a face-centered cubic manner in three-dimensional space through their six-membered ring windows, forming a highly symmetrical microporous framework system.

[0075] Figure 2 The diagram shows the structure of the Cs3Cu2I5:K@PS scintillator film modified with ZIF-8 photonic crystal, which includes a glass substrate, a Cs3Cu2I5:K@PS scintillator film and a ZIF-8 photonic crystal layer arranged sequentially; wherein, the ZIF-8 photonic crystal layer is a three-dimensional periodic structure formed by the self-assembly of ZIF-8 nanoparticles.

[0076] Figure 3 The scanning electron microscopy (SEM) analysis results show that all samples, regardless of size variation, exhibit a consistent and regular truncated dodecahedral morphology. The images also clearly demonstrate that with increasing CTAB concentrations (0.50 mmol / L, 0.54 mmol / L, 0.58 mmol / L, 0.64 mmol / L), the average size of ZIF-8 nanoparticles decreases from 276 ± 10 nm to 95 ± 5 nm, exhibiting a systematic decreasing trend. This phenomenon indicates that by simply adjusting the CTAB concentration, precise "top-down" tailoring of the final size of ZIF-8 crystals can be achieved, thereby obtaining target products with a narrow size distribution within the hundreds of nanometers.

[0077] Figure 4The photoelectric properties of scintillator thin films modified with ZIF-8 photonic crystals of different sizes were demonstrated. Experimental results show that the luminescence intensity was increased by 1 to 2 times and the signal-to-noise ratio was improved by 10 to 30 after introducing an optimized three-dimensional photonic crystal structure on the surface of the Cs3Cu2I5:K@PS thin film. This is because the photonic crystal, after being introduced onto the surface of the scintillator thin film, forms a three-dimensional periodic diffraction grating on the scintillator surface. When photons confined inside the scintillator and propagating at a critical angle greater than θc (their corresponding electromagnetic fields exist as evanescent waves at the interface) encounter the photonic crystal structure on the surface, a diffraction effect occurs. This diffraction changes the propagation direction of the light wave, and the equivalent incident angle of the new propagation direction in the optically less dense medium becomes less than θc. From a macroscopic perspective, this process is equivalent to significantly increasing the effective critical angle of light emission, thus improving the overall light extraction efficiency of the thin film. Crucially, this performance improvement did not come at the expense of spatial resolution.

[0078] Figure 5 The spatial resolution of scintillator films modified with ZIF-8 photonic crystals of different sizes was demonstrated. Compared with the standard sample (comparative example) without photonic crystals, the spatial resolution of the films in Example 1 (276 nm PhCs), Example 2 (124 nm PhCs), Example 3 (101 nm PhCs), and Example 4 (87 nm PhCs) showed no significant loss. This phenomenon indicates that since the photonic crystal structure is a micro-nano modification of the surface or near-surface, its scale is much smaller than the pixel size of the imaging system, and therefore it does not introduce additional optical crosstalk or cause imaging blurring.

[0079] Figure 6 The radiative emission spectra of scintillator films modified with ZIF-8 photonic crystals of different sizes are shown. The examples have luminescence intensities that are 1-2 times higher than those of the comparative examples, demonstrating the superior effectiveness of this strategy in improving the overall performance of scintillators.

[0080] The present invention has been described through the above embodiments. However, it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit the invention to the scope of the described embodiments. Furthermore, those skilled in the art will understand that the present invention is not limited to the above embodiments, and many more variations and modifications can be made based on the teachings of the present invention, all of which fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-light-extraction-efficiency scintillator composite film, characterized in that, This includes a scintillator thin film and a photonic crystal layer located on top of the scintillator thin film; Among them, the scintillator film is formed by coating a slurry prepared from scintillator powder and polymer solution onto a substrate; the photonic crystal layer is a three-dimensional periodic structure formed by the self-assembly of photonic crystal nanoparticles.

2. The high light extraction efficiency scintillator composite film according to claim 1, characterized in that, The photonic crystal nanoparticles in the photonic crystal layer are nanoparticles composed of two or more materials with different dielectric constants.

3. The high light extraction efficiency scintillator composite film according to claim 1, characterized in that, The photonic crystal layer is a three-dimensional structure with periodic side-by-side arrangement in-plane and ordered stacking outside-plane.

4. The high light extraction efficiency scintillator composite film according to claim 1, characterized in that, The scintillator powder is CsCu2I3 powder, Cs3Cu2I5 powder, Cs3Cu2I5:(0.1-5mol%)K powder, CsPbBr3 powder, or CsMnCl3 powder, and the polymer solution is PMMA solution, PS solution, PMDS solution, or PDVF solution.

5. The high light extraction efficiency scintillator composite film according to claim 1, characterized in that, The photonic crystal nanoparticles are ZIF-8, ZIF-67, or ZIF-90, with ZIF-8 nanoparticles having a size of 100-500 nm, ZIF-90 nanoparticles having a size of 50-200 nm, and ZIF-67 nanoparticles having a size of 300-500 nm.

6. A method for preparing a high-light-extraction-efficiency scintillator composite thin film, characterized in that, Includes the following steps: Step 1. Preparation of scintillator slurry: The polymer powder is mixed with solvent C and dissolved to obtain a polymer solution; then the scintillator powder is mixed with the polymer solution and heated and stirred at 50-60℃ for 1-2 hours to obtain a scintillator slurry. Step 2. Preparation of scintillator thin film: The scintillator slurry obtained in step 1 is uniformly coated onto the substrate and cured to obtain a scintillator film. Step 3. Preparation of photonic crystal solution: Step 3.1 Disperse salt A in solvent D to prepare a mixed solution D with a concentration of 50-80 mg / mL; Step 3.2 Disperse additive D in solvent D to prepare a mixed solution E with a concentration of 0.10-0.80 mmol / L; add organic compound A to mixed solution E and stir for 1-2 hours to obtain mixed solution F, in which the concentration of organic compound A is 1-5 mol / L; Step 3.3 Mix the mixture F from step 3.2 with the mixture D from step 3.1 and stir to obtain a crude solution; wherein the volume ratio of mixture D to mixture F is 1:(0.5-1.5). Step 3.4 Disperse additive D in solvent D to prepare a mixed solution G with a concentration of 0.10-0.50 mg / mL; separate the crude solution from step 3.3, add mixed solution G to the separated precipitate, centrifuge twice, and collect the precipitate; Step 3.5 Disperse the precipitate obtained in step 3.4 in mixed solution G to obtain a photonic crystal solution with a concentration of 10-50 mg / mL; Step 4. Preparation of high-light-extraction-efficiency scintillator composite film: The photonic crystal solution from step 3.5 is coated onto the surface of the scintillator film obtained in step 2 and cured to obtain the high light extraction efficiency scintillator composite film.

7. The method for preparing the high light extraction efficiency scintillator composite thin film according to claim 6, characterized in that, In step 1, solvent C is chlorobenzene, toluene, or chloroform; polymer is PMMA, PS, PMDS, or PDVF; scintillator powder is CsCu2I3 powder, Cs3Cu2I5 powder, Cs3Cu2I5:(0.1-5mol%)K powder, CsPbBr3 powder, or CsMnCl3 powder.

8. The method for preparing the high light extraction efficiency scintillator composite thin film according to claim 6, characterized in that, In step 3.1, salt A is zinc acetate dihydrate, magnesium acetate dihydrate, manganese acetate dihydrate, or copper acetate dihydrate; solvent D is ethanol, isopropanol, ultrapure water, or N,N-dimethylformamide.

9. The method for preparing the high light extraction efficiency scintillator composite thin film according to claim 6, characterized in that, In step 3.2, additive D is hexadecyltrimethylammonium bromide, sodium dodecyl sulfate, polyvinylpyrrolidone, or 3-aminopropyltriethoxysilane; organic compound A is 2-methylimidazole, benzimidazole, or triethanolamine.

10. The method for preparing a high-light-extraction-efficiency scintillator composite thin film according to claim 6, characterized in that, The stirring speed in step 3.3 is 200-500 rpm; the separation in step 3.4 is centrifugal separation, with a centrifugation speed of 10,000-11,000 rpm and a centrifugation time of 8-10 min.

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