Method for preparing Cs3Cu2I5:Tl scintillator film by ultrasonic spraying assisted by monomer additives

Abstract

The present invention discloses a method for preparing a Cs3Cu2I5:Tl scintillator film by ultrasonic spraying assisted by a monomer additive. The method comprises dissolving cuprous iodide, cesium iodide, thallium iodide or thallium chloride, hypophosphorous acid and a monomer additive in DMF in proportion to form a precursor solution, then uniformly ultrasonically spraying the precursor solution on a glass substrate heated at 120-150°C, and finally annealing the wet film together with the glass substrate at 120-150°C to obtain Tl + A 0.15% doping Cs3Cu2I5:Tl scintillator film was produced using ultrasonic spraying and the addition of a monomer additive to the precursor solution. This method produces a dense, uniform, and specifically oriented Cs3Cu2I5:Tl scintillator film with a thickness exceeding 100 μm. The film also exhibits significantly enhanced adhesion and good air stability.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of inorganic scintillator materials and relates to a method for preparing a Cs3Cu2I5:Tl scintillator film by ultrasonic spraying assisted by monomer additives. Background Art

[0002] The excellent penetrating power of X-rays has made X-ray imaging widely used in medical diagnosis, industrial non-destructive testing, safety inspection, nuclear safety testing and other fields. As the energy conversion layer in X-ray imaging systems, scintillators can effectively convert high-energy rays into visible light. Currently, common commercial scintillators include NaI:TI and CsI:TI, but they have problems such as high process cost, difficulty in large-scale preparation, poor moisture resistance, and severe afterglow. Metal halide perovskites are considered to be a class of scintillator materials with application prospects due to their advantages such as high fluorescence quantum yield, tunable emission wavelength, simple preparation, low cost, and short afterglow (Nature, 2018, 561(7721), 88-93; ACS Nano, 2019, 13(2), 2520-2525). Among them, copper-based halide scintillators have become one of the most widely studied inorganic metal halides due to their unique advantages such as self-trapped excitons (STE), small self-absorption, large Stokes shift and high fluorescence quantum yield (AOM, 2022, 9(11), 10.1002).

[0003] However, several challenges remain to be addressed in order to realize the practical application of copper-based metal halide scintillators. First, most current literature reports use a simple mixture of powder and polymer, making it difficult to obtain high-quality and uniform scintillator films. The simple mixing of particles and polymers results in significant interfacial scattering, leading to low light extraction efficiency and optical crosstalk. Commercial CsI evaporation processes are costly and inefficient, and have yet to be developed for the Cs3Cu2I5:Tl system. Second, existing preparation techniques struggle to produce dense, thick Cs3Cu2I5:Tl films with specific orientations, which impacts the ultimate X-ray cutoff capability, light extraction efficiency, and imaging resolution. For example, a commonly used method, such as the doctor blade coating method (Chinese Patent 2021116118465), produces films with relatively low RL strength due to the direct addition of polymer. Finally, thick inorganic films suffer from poor adhesion to the substrate. Therefore, there is an urgent need for a technology to prepare high-quality, strongly adherent, and air-stable Cs3Cu2I5:Tl scintillator films. Summary of the Invention

[0004] The present invention aims to provide a method for preparing Cs3Cu2I5:Tl scintillator films by ultrasonic spraying assisted by monomer additives. This method utilizes ultrasonic spraying to produce uniform Cs3Cu2I5:Tl scintillator films with a thickness exceeding 100 μm. The addition of the monomer additive not only enhances film adhesion and induces vertical growth, but also passivates iodine vacancy defects, resulting in excellent air stability in the Cs3Cu2I5:Tl scintillator films.

[0005] The technical solutions for achieving the purpose of the present invention are as follows:

[0006] A method for preparing a Cs3Cu2I5:Tl scintillator film by ultrasonic spraying assisted by a monomer additive comprises the following steps:

[0007] Step 1: cuprous iodide (CuI), cesium iodide (CsI), thallium iodide (TlI) or thallium chloride (TlCl), and monomer additives are mixed and dissolved in dimethylformamide (DMF) with stirring according to a ratio of 8 mmol:12 mmol:0.018 mmol:1.0-1.5 mL to obtain a precursor solution, wherein the monomer additive is selected from one or more of triallyl isocyanate (TAIC), 1,3,5-triallyl cyanurate (TAC), 1,3,5-triacryloylhexahydro-1,3,5-triazine, ethoxylated trimethylolpropane triacrylate (ETPTA), trimethylolpropane trimethacrylate (TMTA), and diethylene glycol methacrylate (DEG);

[0008] Step 2, uniformly ultrasonically spraying the precursor solution onto a clean glass substrate heated at 120-150° C.;

[0009] Step 3: After the ultrasonic spraying is completed, the wet film and the glass substrate are placed at 120-150°C for annealing. After the solvent evaporates completely, Tl + Cs3Cu2I5:Tl scintillator film with a doping amount of 0.15%.

[0010] Preferably, in step 1, the stirring and dissolving temperature is 20 to 80° C., and the stirring time is more than 3 hours.

[0011] Preferably, in step 2, the spraying pressure is 20-30 MPa, and the spray flow rate is 30 μl / min.

[0012] Preferably, in step 2, the spraying temperature is 130°C.

[0013] Preferably, in step 3, the annealing temperature is 120°C.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] (1) The present invention adopts ultrasonic spraying method to prepare Cs3Cu2I5:Tl scintillator film, which is simple to operate and the prepared film is uniform and dense;

[0016] (2) The present invention adds polymer monomers into the Cs3Cu2I5:Tl precursor, which greatly improves the adhesion of the film and induces its vertical growth, achieving directional growth and improving its light extraction efficiency and imaging resolution;

[0017] (3) The polymer monomer added in the present invention contains C=O and C=C bonds, which can passivate iodide ion defects and reduce internal defects of the membrane, thereby improving the air stability of the membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 These are actual pictures of the Cs3Cu2I5:Tl films prepared in Comparative Example 1 and Examples 1, 3, and 4 under irradiation with a fluorescent lamp and a 365nm ultraviolet lamp, respectively.

[0019] Figure 2 These are scanning electron microscope images of the Cs3Cu2I5:Tl scintillator films prepared in Examples 1 to 8, where A is Example 1, B is Example 2, C is Example 3, D is Example 4, E is Example 5, F is Example 6, G is Example 7, and H is Example 8.

[0020] Figure 3 These are scanning electron microscope images of the Cs3Cu2I5:Tl scintillator films prepared in Comparative Examples 2 to 7, where A is Comparative Example 2, B is Comparative Example 3, C is Comparative Example 4, D is Comparative Example 5, E is Comparative Example 6, and E is Comparative Example 7.

[0021] Figure 4 Graphs showing the radiant luminescence intensity of Cs3Cu2I5:Tl scintillator films prepared with different TAIC addition amounts in Example 1, Example 10, Comparative Example 1, Comparative Example 8, and Comparative Example 9.

[0022] Figure 5 These are Fourier transform infrared spectra of the Cs3Cu2I5:Tl scintillator film, TAIC monomer and polymer prepared in Example 1 and Comparative Example 1.

[0023] Figure 6 This is the initial physical picture of the Cs3Cu2I5:Tl scintillator film prepared in Example 1 and the physical comparison picture after storage for 3 months.

[0024] Figure 7 X-ray structure diffraction analysis diagram of the Cs3Cu2I5:Tl scintillator film prepared in Examples 1, 3, 4 and Comparative Example 1.

[0025] Figure 8 Radiant luminescence intensity diagram of the Cs3Cu2I5:Tl scintillator films prepared in Examples 1 and 2.

[0026] Figure 9 This is a graph showing the resolution detection results of the Cs3Cu2I5:Tl scintillator films prepared in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0027] The present invention is further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, modifications of various equivalent forms of the present invention made by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0028] Example 1

[0029] According to the stoichiometric ratio of each element in the chemical formula Cs3Cu2I5, a mixed solution of 12mmol CsI, 8mmol CuI, 0.018mol TlI, 1.5mL triallyl isocyanate (TAIC), 10mL DMF, and 500μl H3PO2 was heated and stirred at 60°C for 4 hours. After complete dissolution, the solution turned into a light yellow clear and transparent liquid, and cooled to obtain a precursor solution. The cleaned glass was placed on a heating table heated at 130°C, 1mL of the precursor solution was placed in the spray gun chamber, the air pressure was adjusted to 20MPa, the spray flow rate was 30μl / min, and continuous spraying was completed (the spraying time was 30±2min). After the spraying was completed, the wet film and the glass substrate were annealed in air at 120°C to promote solvent evaporation. After 2h, Tl grown with the assistance of the additive TAIC was obtained. + Cs3Cu2I5:Tl scintillator film with a doping amount of 0.15%.

[0030] Example 2

[0031] This embodiment is substantially the same as embodiment 1, the only difference being that the thallium salt is TlCl.

[0032] Depend on Figure 8 It can be seen that no matter whether TlI or TlCl is used as the thallium salt, the RL intensity and peak position of the prepared Cs3Cu2I5:Tl scintillator film are the same.

[0033] Example 3

[0034] This embodiment is substantially the same as embodiment 1, except that the additive is replaced with trimethylolpropane trimethacrylate (TMTA).

[0035] Example 4

[0036] This embodiment is substantially the same as embodiment 1, except that the additive is replaced with ethoxylated trimethylolpropane triacrylate (ETPTA).

[0037] Example 5

[0038] This embodiment is substantially the same as embodiment 1, except that the additive is replaced with diethylene glycol dimethacrylate (DEG).

[0039] Example 6

[0040] This embodiment is substantially the same as embodiment 4, except that the additive is replaced with triallyl 1,3,5-cyanurate (TAC).

[0041] Example 7

[0042] This embodiment is substantially the same as embodiment 1, except that the additive is replaced with 1,3,5-triacryloylhexahydro-1,3,5-triazine.

[0043] Example 8

[0044] This embodiment is basically the same as embodiment 1, except that the additive is replaced with a mixture of ethoxylated trimethylolpropane triacrylate (ETPTA) and triallyl isocyanate (TAIC) in a volume ratio of 1:1.

[0045] Example 9

[0046] This embodiment is basically the same as embodiment 1, the only difference being that the annealing temperature is 150°C.

[0047] The RL intensity and peak position of the Cs3Cu2I5:Tl scintillator film prepared in this embodiment are substantially the same as those in Example 1, indicating that a Cs3Cu2I5:Tl scintillator film with excellent performance can be prepared at 120°C to 150°C.

[0048] Example 10

[0049] This example is basically the same as Example 1, except that 1 mL of TAIC is added.

[0050] Example 11

[0051] This embodiment is basically the same as embodiment 1, the only difference being that the temperature of the glass substrate is adjusted to 120° C. during spraying.

[0052] The RL intensity and peak position of the Cs3Cu2I5:Tl scintillator film prepared in this embodiment are roughly the same as those in Example 1.

[0053] Example 12

[0054] This embodiment is basically the same as embodiment 1, the only difference being that the temperature of the glass substrate is adjusted to 150° C. during spraying.

[0055] The RL intensity and peak position of the Cs3Cu2I5:Tl scintillator film prepared in this embodiment are substantially the same as those in embodiment 1. From embodiment 1, embodiment 11, and embodiment 12, it can be shown that the RL intensity and peak position of the Cs3Cu2I5:Tl scintillator film prepared at a heating temperature of 120-150°C are the same.

[0056] Comparative Example 1

[0057] This comparative example is basically the same as Example 1, except that TAIC is not added.

[0058] Comparative Example 2

[0059] This comparative example is basically the same as Example 1, except that the additive is replaced with polycarbonate (PC).

[0060] Comparative Example 3

[0061] This comparative example is basically the same as Example 1, except that the additive is replaced with polypropylene (PP).

[0062] Comparative Example 4

[0063] This comparative example is basically the same as Example 1, except that the additive is replaced with polypropylene carbonate (PPC).

[0064] Comparative Example 5

[0065] This comparative example is substantially the same as Example 1, except that the additive is replaced with polymethylene polyphenyl polyisocyanate (PAPI).

[0066] Comparative Example 6

[0067] This comparative example is basically the same as Example 1, except that the additive is replaced with toluene diisocyanate (TDI).

[0068] Comparative Example 7

[0069] This comparative example is basically the same as Example 1, except that the additive is replaced with diphenylmethane diisocyanate (MDI).

[0070] Comparative Example 8

[0071] This comparative example is basically the same as Example 1, except that 0.5 mL of TAIC was added.

[0072] Comparative Example 9

[0073] This comparative example is basically the same as Example 1, except that 2 mL of TAIC was added.

[0074] Performance test case

[0075] 1. Light source excitation detection

[0076] The Cs3Cu2I5:Tl films prepared in Comparative Example 1 and Examples 1, 3, and 4 were irradiated with fluorescent lamps and 365nm ultraviolet lamps. The results are as follows: Figure 1 As shown, it can be seen that the surface morphology and luminescence brightness of the Cs3Cu2I5:Tl film with TAIC added are the best.

[0077] 2.SEM observation

[0078] The Cs3Cu2I5:Tl scintillator films prepared in Examples 1 to 8 and Comparative Examples 2 to 7 were photographed by scanning electron microscope (SEM). Figure 2 、 Figure 3 It can be seen that the grains in Example 1 grow in a good columnar crystal morphology, and the film thickness is 100±20 μm. The grains in Examples 3 to 7 also grow in a columnar crystal morphology, but the grains in Comparative Examples 2 to 7 do not grow in an oriented manner.

[0079] 3.Radioluminescence (RL) intensity detection

[0080] The Cs3Cu2I5:Tl scintillator films prepared in Example 1, Example 10, Comparative Example 1, Comparative Example 8, and Comparative Example 9 were subjected to X-ray excitation, and spectral data were collected using a fluorescence spectrometer. The comparison of the radiation luminescence intensity of the Cs3Cu2I5:Tl scintillator film samples with different TAIC addition amounts was obtained. Figure 4 As shown. Figure 4 It can be seen that the luminescence efficiency is better when the addition amount is 1.0 and 1.5 mL, and the luminescence efficiency is the best when the addition amount is 1.5 mL. When the TAIC addition amount is too small, the film oxidation rate is faster, and it will turn yellow or black during the annealing process. When the addition amount is too much, its RL intensity decreases a lot.

[0081] 4. Infrared spectroscopy detection

[0082] By performing Fourier transform infrared spectroscopy on the Cs3Cu2I5:Tl scintillator film prepared in Example 1 and Comparative Example 1, as well as the TAIC monomer and its polymer, the Fourier transform infrared spectra thereof are obtained. Figure 5 As shown. Figure 5 The disappearance of C=C corresponding to the peak 1647 indicates that TAIC in Example 1 has successfully cross-linked and polymerized. The shift of C=O corresponding to the peak 1678 indicates that TAIC has reacted with Cs3Cu2I5.

[0083] 5. Storage status (after three months) inspection

[0084] Comparing the storage state (three months later) of the Cs3Cu2I5:Tl scintillator film prepared in Example 1, the sample has good stability and no yellowing or deterioration. Figure 6 shown.

[0085] 6.XRD detection

[0086] X-ray diffraction analysis was performed on the Cs3Cu2I5:Tl scintillator films prepared in Examples 1, 3, 4 and Comparative Example 1. The results are as follows: Figure 7 As shown. Figure 7 It can be seen that after adding the additive, the Cs3Cu2I5:Tl scintillator film has no impurity peaks, proving that it is a pure phase. The half-peak width of Example 1 is significantly smaller than that of Examples 3, 4 and Comparative Example 1, indicating that when TAIC is used as an additive, the crystallinity of the crystal is better.

[0087] 7. Resolution detection

[0088] The resolution of the Cs3Cu2I5:Tl scintillator films prepared in Example 1 and Comparative Example 1 was tested. Figure 9 As shown, the resolution of the Cs3Cu2I5:Tl scintillator film prepared in Comparative Example 1 without adding the monomer additive is significantly lower than the resolution of the Cs3Cu2I5:Tl scintillator film prepared in Example 1 with adding the monomer additive, indicating that the presence of the monomer additive improves the density of the scintillator film and its substrate adhesion.

Claims

1. A method for preparing a Cs3Cu2I5:Tl scintillator film by ultrasonic spraying assisted by a monomer additive, characterized in that: The following steps are involved: Step 1: cuprous iodide, cesium iodide, thallium iodide or thallium chloride, and monomer additive are mixed in a ratio of 8 mmol:12 mmol:0.018 mmol:1.0-1.5 mL, and dissolved in dimethylformamide with stirring to obtain a precursor solution, wherein the monomer additive is selected from one or more of triallyl isocyanurate, 1,3,5-triallyl cyanurate, 1,3,5-triacryloyl hexahydro-1,3,5-triazine, ethoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, and diethylene glycol dimethacrylate; Step 2, uniformly ultrasonically spraying the precursor solution onto a clean glass substrate heated at 120-150°C; Step 3: After the ultrasonic spraying is completed, the wet film and the glass substrate are placed at 120-150°C for annealing. After the solvent evaporates completely, Tl + Cs3Cu2I5:Tl scintillator film with a doping amount of 0.15%.

2. The method according to claim 1, characterized in that In step 1, the stirring and dissolving temperature is 20-80° C., and the stirring time is more than 3 hours.

3. The method according to claim 1, wherein In step 2, the spraying pressure is 20-30 MPa, and the spray flow rate is 30 μl / min.

4. The method according to claim 1, wherein In step 2, the spraying temperature is 130°C.

5. The method according to claim 1, wherein In step 3, the annealing temperature is 120°C.

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