Rare earth doped perovskite single crystal material, preparation method and application thereof, X-ray indirect detector and preparation method thereof

Abstract

The invention belongs to the technical field of crystal materials, and particularly relates to a single crystal perovskite material, a preparation method and application thereof, an X-ray indirect detector and a preparation method thereof. The single crystal perovskite material provided by the invention is prepared by combining the perovskite material and rare earth ions, so that the unique advantages of the perovskite material and the rare earth ions are brought into full play, and the bottleneck problems that a rare earth quantum cutting scintillator is long in response time, the quantum cutting luminous efficiency is not ideal, the luminous mechanism is not clear and the like are perfectly solved; the obtained novel scintillation material has the advantages of high light yield, fast attenuation, low detection limit and the like, and can meet the application requirements in the aspects of safety inspection, medical diagnosis and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of crystal materials, and in particular relates to a rare earth doped perovskite single crystal material and a preparation method and application thereof, an X-ray indirect detector and a preparation method thereof. Background Art

[0002] As the world's attention to fields such as radiation safety and nuclear medicine continues to increase, the market demand for scintillator detectors has shown a trend of sustained growth. Especially in cutting-edge fields such as medical imaging, industrial detection, and safety inspection, scintillator detectors are widely used and play an important role. Scintillator materials are key components of scintillator detectors, and their quality and performance directly affect the detection capability and measurement accuracy of scintillator detectors. However, the performance of traditional scintillator materials has reached its limit and cannot fully meet the growing market demand. Therefore, researchers need to solve this problem and develop new scintillator materials.

[0003] Metal halide perovskites and their derivatives have shown great application prospects in the field of scintillator detectors due to their high bulk resistivity, high fluorescence quantum efficiency, low cost, large mobility lifetime product, tunable optical band gap, simpler manufacturing process and integrated circuit compatibility compared with traditional semiconductor materials (Si, α-Se, CsI:Tl). However, as far as the current research status is concerned, the research on perovskite scintillators is still in its infancy, and there are still some problems that need to be solved: (1) Severe self-absorption. The large size of perovskite scintillators (single crystals can reach millimeter level) and small Stokes shift lead to serious self-absorption and reduced light yield; (2) Low fluorescence quantum efficiency. Metal halide perovskites mainly absorb and emit visible light, and the excitons of three-dimensional single crystal materials have the characteristics of spatial unrestrictedness, which leads to weak luminescence and poor fluorescence tunability; (3) Poor scintillation performance at room temperature. Due to the low binding energy of excitons, thermal quenching is easily induced, resulting in poor scintillation performance of perovskites at room temperature, which greatly limits the further development of scintillator detectors.

[0004] So far, researchers have conducted a lot of experimental explorations on improving the scintillation performance of perovskite materials, and found that doping is beneficial to improving the light yield and energy resolution of scintillators, and also has a positive effect on improving the detection performance of detectors. By introducing transition metals or rare earth metals into halide perovskites, new doped luminescence can be induced. This effect is affected by the energy transfer from the host to the doped ions, which can facilitate the effective separation of the absorption spectrum and emission spectrum of the material, increase the Stokes shift and reduce the self-absorption phenomenon. In addition, this method can also effectively avoid the non-radiative recombination of excitons and improve the photoluminescence quantum efficiency of the material.

[0005] However, the current doped perovskite materials still have the defects of low quantum cutting luminescence efficiency and long response time of quantum cutting scintillators. Summary of the Invention

[0006] The purpose of the present invention is to provide a rare earth doped perovskite single crystal material, its preparation method and application, an X-ray indirect detector and its preparation method. The single crystal perovskite material provided by the present invention has the advantages of high quantum cutting luminescence efficiency and short response time of quantum cutting scintillators.

[0007] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0008] The present invention provides a rare earth doped perovskite single crystal material, and the chemical composition of the rare earth doped perovskite single crystal material is CsB 1-y-z Yb y RE z X 3 , where B is Pb and / or Cd, X is Br and / or Cl, RE is a rare earth element other than Yb, the value range of y is 0.05 - 0.25, and the value range of z is 0 - 0.20.

[0009] Preferably, the RE is at least one of Sm, Dy, Tb, Pr, Ce, Nd and Er.

[0010] The present invention also provides a preparation method of the rare earth doped perovskite single crystal material described in the above technical solution. When X is Br or Cl, it is denoted as Preparation Method 1, and the Preparation Method 1 includes the following steps:

[0011] Mix the B source, rare earth acetate, cesium source and hydrohalic acid, and then carry out hydrothermal reaction and cooling treatment in sequence to obtain the rare earth doped perovskite single crystal material; the hydrohalic acid includes hydrochloric acid or hydrobromic acid; the rare earth acetate includes ytterbium acetate and RE-containing acetate.

[0012] When X is Br and Cl, it is denoted as Preparation Method 2, and the Preparation Method 2 includes the following steps:

[0013] Mix the B source, cesium source, rare earth acetate and hydrochloric acid for the first time to obtain a chlorine-containing precursor solution;

[0014] Mix the B source, cesium source, rare earth acetate and hydrobromic acid for the second time to obtain a bromine-containing precursor solution;

[0015] Mix the chlorine-containing precursor solution and the bromine-containing precursor solution, and then carry out hydrothermal reaction and cooling treatment in sequence to obtain the rare earth doped perovskite single crystal material;

[0016] The rare earth acetate includes ytterbium acetate and RE-containing acetate.

[0017] Preferably, the B source includes acetate salts, and the acetate salts include lead acetate and / or cadmium acetate; the cesium source includes cesium acetate.

[0018] Preferably, the amount of ytterbium acetate is 5-25% of the amount of the B source in terms of the amount of substance;

[0019] The amount of the RE acetate is 0-20% of the amount of the B source in terms of the amount of substance;

[0020] In terms of the amount of substance of the elements, the molar ratio of the B source to the cesium source is 1-y-z:1, where the value range of y is 0.05-0.25, and the value range of z is 0-0.20;

[0021] In the preparation method 1, the concentration of the hydrochloric acid is 35-37 wt%, and the concentration of the hydrobromic acid is 48 wt%; the dosage ratio of the B source to the hydrohalic acid is 1 mmol:12 mL;

[0022] In the preparation method 2, the concentration of the hydrochloric acid is 35-37 wt%, and the concentration of the hydrobromic acid is 48 wt%; the dosage ratio of the B source to the hydrochloric acid is 1 mmol:12 mL, and the dosage ratio of the B source to the hydrobromic acid is 1 mmol:12 mL; the volume ratio of the chlorine-containing precursor solution to the bromine-containing precursor solution is 1-11:1-11, and the total volume of the chlorine-containing precursor solution and the bromine-containing precursor solution is 12 mL.

[0023] Preferably, the temperature of the hydrothermal reaction is 200-240 °C, and the heat preservation time is 12-24 h.

[0024] Preferably, the cooling rate of the cooling treatment is 2-4 °C / min.

[0025] The present invention also provides the application of the rare earth-doped perovskite single crystal material described in the above technical solution or the rare earth-doped perovskite single crystal material prepared by the preparation method described in the above technical solution as a scintillator material in a detector.

[0026] The present invention also provides an X-ray indirect detector, which includes an SiPM substrate and a detector material located on the surface of the SiPM substrate, and the detector material is the rare earth-doped perovskite single crystal material described in the above technical solution or the rare earth-doped perovskite single crystal material prepared by the preparation method described in the above technical solution.

[0027] The present invention also provides a preparation method of the X-ray indirect detector described in the above technical solution, including the following steps:

[0028] Fix the detector material on the surface of the SiPM substrate through a UV curable adhesive.

[0029] The present invention provides a rare-earth doped perovskite single crystal material, and the chemical composition of the rare-earth doped perovskite single crystal material is CsB 1-y-z Yb y RE z X 3 , where B is Pb and / or Cd, X is Br and / or Cl, RE is a rare-earth element other than Yb, the value range of y is 0.05-0.25, and the value range of z is 0-0.20.

[0030] The beneficial effects of the present invention include:

[0031] (1) The present invention uses different rare-earth ions for doping to obtain a rare-earth doped perovskite single crystal material, so that the quantum cutting luminescence efficiency is greatly improved; it can not only provide a series of original achievements for the practical application of rare-earth quantum cutting scintillators, but also promote the development of the X-ray detection field and improve China's international competitiveness in the core industry;

[0032] (2) The rare-earth doped perovskite single crystal material provided by the present invention combines the perovskite material and rare-earth ions. It not only gives full play to the unique advantages of both, but also perfectly solves the bottleneck problems such as long response time, unsatisfactory quantum cutting luminescence efficiency and unclear luminescence mechanism of rare-earth quantum cutting scintillators. The obtained new scintillating material has the advantages of high light yield, fast decay, low detection limit, etc., and can meet the application requirements in aspects such as security inspection and medical diagnosis.

[0033] The present invention also provides a preparation method of the rare-earth doped perovskite single crystal material described in the above technical solution. The present invention first uses a hydrothermal method to prepare a single crystal perovskite material doped with rare-earth ions. The preparation method and process are both simple and easy to operate, and can greatly save costs. Brief Description of the Drawings

[0034] Figure 1 is a schematic flow chart of the preparation method provided by the present invention;

[0035] Figure 2 is a physical diagram of the rare-earth doped perovskite single crystal materials obtained in Examples 1-3;

[0036] Figure 3 is an X-ray diffraction pattern of the rare-earth doped perovskite single crystal materials obtained in Examples 1-3;

[0037] Figure 4 is an absorption spectrum diagram of the rare-earth doped perovskite single crystal materials obtained in Examples 1-3;

[0038] Figure 5 is a fluorescence spectrum diagram of the rare-earth doped perovskite single crystal materials obtained in Examples 1-3;

[0039] Figure 6 Schematic diagram of single-pixel X-ray imaging measurement of the detector prepared in Example 16;

[0040] Figure 7 Physical map of the rare earth-doped perovskite single crystal materials obtained in Example 1 and Examples 4-8;

[0041] Figure 8 X-ray diffraction pattern of the rare earth-doped perovskite single crystal materials obtained in Example 1 and Examples 4-8;

[0042] Figure 9 XPS spectra of the rare earth-doped perovskite single crystal materials obtained in Example 5, Example 7 and Example 1;

[0043] Figure 10 Schematic diagram of the scintillation luminescence mechanism of the single crystal perovskite material with coexisting Br and Cl in the present invention;

[0044] Figure 11 Bar chart of fluorescence quantum efficiency of the rare earth-doped perovskite single crystal materials obtained in Example 1 and Examples 9-15;

[0045] Figure 12 Scintillation performance characterization spectrum of the rare earth-doped perovskite single crystal material obtained in Example 7. Detailed implementation manners

[0046] The present invention provides a rare earth-doped perovskite single crystal material, and the chemical composition of the rare earth-doped perovskite single crystal material is CsB 1-y-z Yb y RE z X 3 , where B is Pb and / or Cd, X is Br and / or Cl, RE is a rare earth element other than Yb, the value range of y is 0.05-0.25, and the value range of z is 0-0.20.

[0047] In the present invention, the value range of y is 0.05-0.25, specifically it can be 0.05, 0.10, 0.15, 0.20, 0.25. In the present invention, the value range of z is 0-0.20, specifically it can be 0, 0.05, 0.10, 0.15, 0.20. In the present invention, RE is preferably at least one of Sm, Dy, Tb, Pr, Ce, Nd and Er.

[0048] The present invention also provides a preparation method of the rare earth-doped perovskite single crystal material described in the above technical solution.

[0049] In the present invention, when X is Br or Cl, it is denoted as Preparation Method 1, and the Preparation Method 1 includes the following steps:

[0050] Mix the B source, rare earth acetate, cesium source and hydrohalic acid, and then carry out hydrothermal reaction and cooling treatment in sequence to obtain the rare earth-doped perovskite single crystal material; the hydrohalic acid includes hydrochloric acid or hydrobromic acid; the rare earth acetate includes ytterbium acetate and RE-containing acetate.

[0051] In the present invention, the B source preferably includes acetate; the acetate preferably includes lead acetate and / or cadmium acetate. In the present invention, the cesium source preferably includes cesium acetate (CH 3 COOCs). In the present invention, the ytterbium acetate is preferably Yb(C 2 H 3 O 2 ) 3 ·xH 2 O; the RE-containing acetate preferably includes Ce(C 2 H 3 O 2 ) 3 ·xH 2 O, Tb(C 2 H 3 O 2 ) 3 ·xH 2 O, Sm(C 2 H 3 O 2 ) 3 ·xH 2 O, Nd(C 2 H 3 O 2 ) 3 ·xH 2 O, Er(C 2 H 3 O 2 ) 3 ·xH 2 O, Dy(C 2 H 3 O 2 ) 3 ·xH 2 O and Pr(C 2 H 3 O 2 ) 3 ·xH 2 O, at least one of them.

[0052] In the present invention, the amount of ytterbium acetate is preferably 5-25% of the amount of B source; the amount of RE-containing acetate is preferably 0-20% of the amount of B source; in terms of the amount of elements, the molar ratio of the B source to the cesium source is preferably 1-y-z:1, where the value range of y is preferably 0.05-0.25, and the value range of z is preferably 0-0.20. In the present invention, the concentration of hydrochloric acid is preferably 35-37 wt%, and the concentration of hydrobromic acid is preferably 48 wt%; the dosage ratio of the B source to the hydrohalic acid is preferably 1 mmol:12 mL.

[0053] In the present invention, the mixing process preferably includes:

[0054] Premix the B source, rare earth acetate, and part of the hydrohalic acid to obtain a premixed solution;

[0055] Disperse the cesium source in the remaining hydrohalic acid, and then add it to the premixed solution and stir to mix.

[0056] In the present invention, the temperature of the stirring and mixing is preferably 60 °C, and the time is preferably 12 h.

[0057] In the present invention, the temperature of the hydrothermal reaction is preferably 200-240 °C, and the heat preservation time is preferably 12-24 h. In the present invention, the hydrothermal reaction is preferably carried out in a reaction kettle. In the present invention, the cooling rate of the cooling treatment is preferably 2-4 °C / min. In the present invention, the temperature after the cooling treatment is preferably room temperature. After the cooling treatment, the present invention also preferably includes drying the obtained system.

[0058] In the present invention, when X is Br and Cl, it is denoted as Preparation Method 2, and the Preparation Method 2 includes the following steps:

[0059] First mix the B source, cesium source, rare earth acetate, and hydrochloric acid to obtain a chlorine-containing precursor solution;

[0060] Second mix the B source, cesium source, rare earth acetate, and hydrobromic acid to obtain a bromine-containing precursor solution;

[0061] After mixing the chlorine-containing precursor solution and the bromine-containing precursor solution, perform hydrothermal reaction and cooling treatment in sequence to obtain the rare earth-doped perovskite single crystal material; the rare earth acetate includes ytterbium acetate and RE-containing acetate.

[0062] In the present invention, the types and dosages of the B source, cesium source, and rare earth acetate are preferably the same as those defined in the above technical solution, and will not be elaborated here.

[0063] In the present invention, the concentration of the hydrochloric acid is preferably 35-37 wt%, and the concentration of the hydrobromic acid is preferably 48 wt%; the dosage ratio of the B source to the hydrochloric acid is preferably 1 mmol: 12 mL, and the dosage ratio of the B source to the hydrobromic acid is preferably 1 mmol: 12 mL; the volume ratio of the chlorine-containing precursor solution to the bromine-containing precursor solution is preferably 1-11: 1-11, and the total volume of the chlorine-containing precursor solution and the bromine-containing precursor solution is preferably 12 mL.

[0064] In the present invention, both the first mixing and the second mixing are preferably carried out under stirring conditions, the temperature of the stirring is preferably 60 °C, and the time is preferably 12 h.

[0065] In the present invention, the condition parameters of the hydrothermal reaction and the cooling treatment are preferably the same as those defined in the above technical solution, and will not be elaborated here.

[0066] In the present invention, the flow schematic diagram of the preparation method is as Figure 1 shown.

[0067] The present invention also provides an application of the rare earth-doped perovskite single crystal material described in the above technical solution or the rare earth-doped perovskite single crystal material prepared by the preparation method described in the above technical solution as a scintillator material in a detector.

[0068] The present invention also provides an X-ray indirect detector, including a SiPM substrate and a detector material located on the surface of the SiPM substrate, and the detector material is the rare earth-doped perovskite single crystal material described in the above technical solution or the rare earth-doped perovskite single crystal material prepared by the preparation method described in the above technical solution.

[0069] The present invention also provides a preparation method of the X-ray indirect detector described in the above technical solution, including the following steps:

[0070] Fix the detector material on the surface of the SiPM substrate through a UV curable adhesive.

[0071] In the present invention, the size of the detector material is preferably 5 mm × 5 mm × 1.5 mm.

[0072] In the present invention, the fixing process is preferably: coat the UV curable adhesive at the four corners of one side surface of the detector material, then adhere it to the surface of the SiPM substrate, and carry out UV lamp irradiation curing. The present invention has no special limitation on the type and dosage of the UV curing agent, and those well-known to those skilled in the art can be used. In the present invention, the time of the UV lamp irradiation curing is preferably 1 min.

[0073] In the present invention, during the use of the X-ray indirect detector, the detector material is exposed to X-rays, and a Keithley 2400 is used to collect electrical signals.

[0074] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0075] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0076] Example 1

[0077] Dissolve 1 mmol of lead acetate and 0.15 mmol of ytterbium acetate in 10 mL of hydrochloric acid (concentration: 35 - 37 wt%) to form a transparent solution;

[0078] Add the mixed solution formed by 1 mmol of cesium acetate and 2 mL of hydrochloric acid (concentration: 35 - 37 wt.%) to the above-obtained transparent solution, stir at 60 °C for 12 h, and transfer it to a reaction kettle;

[0079] Place the above reaction kettle in an oven at 200 °C for heat preservation for 24 h, and then cool it to room temperature at a rate of 2 °C / h; after drying, obtain a single-crystal perovskite material, denoted as CsPb 0.85 Yb 0.15 Cl 3 .

[0080] Example 2

[0081] Prepare the single-crystal perovskite material in the same manner as in Example 1, where 1 mmol of lead acetate is replaced by 1 mmol of cadmium acetate, denoted as CsCd 0.85 Yb 0.15 Cl 3 .

[0082] Example 3

[0083] Prepare the single-crystal perovskite material in the same manner as in Example 1, where 1 mmol of lead acetate is replaced by 0.5 mmol of lead acetate and 0.5 mmol of cadmium acetate, denoted as CsPb 0.425 Cd 0.425 Yb 0.15 Cl 3 .

[0084] Example 4

[0085] Prepare the single-crystalline perovskite material in the same manner as in Example 1, where hydrochloric acid is replaced with hydrobromic acid with a concentration of 48 wt%, denoted as CsPb 0.85 Yb 0.15 Br 3 .

[0086] Example 5

[0087] Put 1 mmol of lead acetate, 1 mmol of cesium acetate, and 0.15 mmol of ytterbium acetate into a glass vial containing 12 mL of hydrochloric acid (with a concentration of 35 - 37 wt%), and stir at 60 °C for 12 h to obtain a chlorine-containing precursor solution;

[0088] Put 1 mmol of lead acetate, 1 mmol of cesium acetate, and 0.15 mmol of ytterbium acetate into a glass vial containing 12 mL of hydrobromic acid (with a concentration of 48 wt%), and stir at 60 °C for 12 h to obtain a bromine-containing precursor solution;

[0089] Mix the chlorine-containing precursor solution and the bromine-containing precursor solution in a volume ratio of 1:5, and transfer it to a reaction kettle; put the reaction kettle into an oven at 200 °C and keep it warm for 24 h, then cool it to room temperature at a rate of 2 °C / h; after drying, obtain the single-crystalline perovskite material, denoted as CsPb 0.85 Yb 0.15 Cl 0.5 Br 2.5 .

[0090] Example 6

[0091] Prepare the single-crystalline perovskite material in the same manner as in Example 5, where the chlorine-containing precursor solution and the bromine-containing precursor solution are mixed in a volume ratio of 1:2, denoted as CsPb 0.85 Yb 0.15 ClBr 2 .

[0092] Example 7

[0093] Prepare the single-crystalline perovskite material in the same manner as in Example 5, where the chlorine-containing precursor solution and the bromine-containing precursor solution are mixed in a volume ratio of 1:1, denoted as CsPb 0.85 Yb 0.15 Cl 1.5 Br 1.5 .

[0094] Example 8

[0095] Prepare the single-crystalline perovskite material in the same manner as in Example 5, where the chlorine-containing precursor solution and the bromine-containing precursor solution are mixed in a volume ratio of 2:1, denoted as CsPb 0.85 Yb 0.15 Cl 2 Br1 。

[0096] Example 9

[0097] Dissolve 1 mmol of lead acetate, 0.15 mmol of ytterbium acetate, and 0.05 mmol of erbium acetate in 10 mL of hydrochloric acid (concentration: 35 - 37 wt%) to form a transparent solution;

[0098] Add a mixed solution formed by 1 mmol of cesium acetate and 2 mL of hydrochloric acid (concentration: 35 - 37 wt%) to the above - obtained transparent solution, stir at 60 °C for 12 h, and transfer it to a reaction kettle;

[0099] Place the above reaction kettle in an oven at 200 °C for heat preservation for 24 h, and then cool it to room temperature at a rate of 2 °C / h; after drying, a single - crystal perovskite material is obtained, denoted as CsPb 0.8 Yb 0.15 Er 0.05 Cl 3. 。

[0100] Example 10

[0101] Prepare the single - crystal perovskite material in the same way as in Example 9, where 0.05 mmol of erbium acetate is replaced by 0.05 mmol of neodymium acetate, denoted as CsPb 0.8 Yb 0.15 Nd 0.05 Cl 3 。

[0102] Example 11

[0103] Prepare the single - crystal perovskite material in the same way as in Example 9, where 0.05 mmol of erbium acetate is replaced by 0.05 mmol of terbium acetate, denoted as CsPb 0.8 Yb 0.15 Tb 0.05 Cl 3 。

[0104] Example 12

[0105] Prepare the single - crystal perovskite material in the same way as in Example 9, where 0.05 mmol of erbium acetate is replaced by 0.05 mmol of dysprosium acetate, denoted as CsPb 0.8 Yb 0.15 Dy 0.05 Cl 3 。

[0106] Example 13

[0107] Prepare the single - crystal perovskite material in the same way as in Example 9, where 0.05 mmol of erbium acetate is replaced by 0.05 mmol of cerium acetate, denoted as CsPb 0.8 Yb0.15 Ce 0.05 Cl 3 。

[0108] Example 14

[0109] The single-crystal perovskite material was prepared in the same manner as in Example 9, wherein 0.05 mmol of erbium acetate was replaced with 0.05 mmol of samarium acetate, denoted as CsPb 0.8 Yb 0.15 Sm 0.05 Cl 3 。

[0110] Example 15

[0111] The single-crystal perovskite material was prepared in the same manner as in Example 9, wherein 0.05 mmol of erbium acetate was replaced with 0.05 mmol of praseodymium acetate, denoted as CsPb 0.8 Yb 0.15 Pr 0.05 Cl 3 。

[0112] Example 16

[0113] The rare-earth doped perovskite single-crystal material obtained in Example 1 was processed into a size of 5 mm × 5 mm × 1.5 mm. UV curable glue was applied to the four corners of the lower surface of the processed material and placed on the surface of the SiPM substrate; subsequently, it was irradiated with a UV lamp for 1 min to cure the UV curable glue, coupling the calcium single-crystal perovskite material to the SiPM to obtain an X-ray indirect detector.

[0114] Performance Test

[0115] Test Example 1

[0116] Figure 2 The physical pictures of the rare-earth doped perovskite single-crystal materials obtained in Examples 1 to 3 are shown. From left to right, they are Example 1, Example 2, and Example 3; it can be seen that the samples have smooth and flat surfaces. As the B source changes, the crystal morphology gradually changes from a square shape (B source is lead acetate) to a hexagonal shape (B source is a 1:1 mixture of lead acetate and cadmium acetate) and a cubic shape (B source is cadmium acetate), indicating that Pb 2+ ions are successfully replaced by Cd 2+ ions.

[0117] Figure 3 The X-ray diffraction patterns of the rare-earth doped perovskite single-crystal materials obtained in Examples 1 to 3 are shown. From Figure 3 it can be seen that as the Cd 2+ ion content gradually increases, the small-angle diffraction peaks disappear, and some new diffraction peaks (2θ = 24.022, 34.058, and 42.110) appear, which are consistent with CsCdCl3 The peak positions correspond one by one to those of the standard hexagonal phase (JCPDS: 70-1615).

[0118] Figure 4 Absorption spectra of the rare-earth doped perovskite single crystal materials obtained in Examples 1 to 3. It can be seen from Figure 4 Cd 2+ After the ions replace Pb 2+ ions, the absorption band has a slight blue shift. This is because the Cd 2+ ionic radius is smaller than that of Pb 2+ ionic radius The replacement of Pb 2+ ions results in lattice contraction.

[0119] Figure 5 Fluorescence spectra of the rare-earth doped perovskite single crystal materials obtained in Examples 1 to 3. It can be seen from Figure 5 that: A sharp exciton emission peak can be observed at 430 nm in the CsPb 0.85 Yb 0.15 Cl 3 single crystal. When the Cd 2+ ions gradually replace the Pb 2+ ions, the exciton emission peak gradually blue shifts and its intensity gradually decreases. This phenomenon is mainly due to the lattice contraction caused by the replacement of Pb 2+ ions by Cd 2+ ions and the energy transfer from the perovskite matrix to the Yb 3+ ions, which is consistent with the literature reports on rare-earth ion doped perovskite nanocrystals. It can also be observed from the spectra that there is a sharp emission band near 980 nm in the single crystal, and its emission intensity is significantly higher than that of the exciton emission of the perovskite host. This emission band is mainly due to the 3+ F 2 - 5 / 2 F 2 transition of Yb 7 / 2 ions.

[0120] Test Example 2

[0121] Figure 6 Schematic diagram of single-pixel X-ray imaging measurement of the detector prepared in Example 16. It can be seen from Figure 6 that: The single-pixel X-ray detector based on the CsPb 0.85 Yb 0.15 Cl 3 single crystal scintillator can identify a clear and high-contrast "JLU" X-ray image similar to the original metal mask, indicating that CsPb 0.85 Yb 0.15 Cl 3Single crystal scintillation detectors have excellent imaging capabilities.

[0122] Test Example 3

[0123] Figure 7 These are physical pictures of the rare earth doped perovskite single crystal materials obtained in Example 1 and Examples 4 - 8. From right to left, they are Example 4, Example 5, Example 6, Example 7, Example 8, and Example 1. It can be seen that as the concentration of Br - ions increases, the crystal gradually changes from colorless and transparent (CsPb 0.85 Yb 0.15 Cl 3 single crystal) to yellow (CsPb 0.85 Yb 0.15 Cl 2 Br 1 and CsPb 0.85 Yb 0.15 Cl 1.5 Br 1.5 ) and red (CsPb 0.85 Yb 0.15 Cl 1 Br 2 、CsPb 0.85 Yb 0.15 Cl 0.5 Br 2.5 and CsPb 0.85 Yb 0.15 Br 3 ). This indicates that Cl - ions in the perovskite single crystal are successfully replaced by Br - ions.

[0124] Figure 8 These are powder X - ray diffraction patterns of the rare earth doped perovskite single crystal materials obtained in Example 1 and Examples 4 - 8. From Figure 8 it can be seen that as the concentration of Br - ions increases, the diffraction peaks gradually shift towards the small - angle side, but there is no impact on the lattice structure of the cations.

[0125] Figure 9 These are XPS spectra of the rare earth doped perovskite single crystal materials obtained in Example 5, Example 7, and Example 1. From Figure 9 it can be seen that in CsPb 0.85 Yb 0.15 Cl 1.5 Br 1.5 and CsPb 0.85 Yb 0.15 Cl 0.5 Br 2.5In the XPS spectrum of the single crystal, there are signal peaks of Cs, Cl, Br, and Yb elements, indicating that Br - ions are successfully introduced into the perovskite CsPb 0.85 Yb 0.15 Cl 3 single crystal.

[0126] Figure 10 This is a schematic diagram of the scintillation luminescence mechanism of the rare-earth-doped perovskite single crystal material with coexisting Br and Cl in the present invention. It can be seen from Figure 10 that under X-ray excitation, the scintillation luminescence process of the single crystal material includes three stages: conversion, transmission, and luminescence. That is, the incident X-ray interacts with the lattice atoms of the single crystal material to generate hot electrons and holes, which then enter the conduction band and valence band of the material through thermal relaxation or are trapped by the defects of the single crystal material. Since the doping of rare-earth ions reduces the defects in the single crystal material, hot electrons and holes are more likely to populate the conduction / valence bands. Then, part of the electrons and holes directly recombine to form an exciton emission spectrum, and the other part transfers to the energy level twice the energy required for Yb 3+ ion emission, and then two near-infrared photons (~980 nm) are emitted. Therefore, the rare-earth-ion-doped perovskite single crystal material is named a quantum cutting scintillator.

[0127] Figure 11 This is a bar chart of the fluorescence quantum efficiency of the rare-earth-doped perovskite single crystal materials obtained in Example 1 and Examples 9-15. Among them, CsPbCl 3 represents no rare-earth ion doping. It can be seen from Figure 11 that after Yb 3+ ion doping, the overall PLQY of the CsPbCl 3 single crystal has been greatly improved, from 13.6% of the undoped to 136.5%. Such a high PLQY comes from the quantum cutting process in the CsPb 0.85 Yb 0.15 Cl 3 single crystal, that is, after the material absorbs energy, the electrons are excited to the conduction band of the perovskite material, and then relax to the energy level twice the energy of the Yb 3+ ion 2 F 5 / 2 - 2 F 7 / 2 transition energy level, and finally directly emit two (~980 nm) near-infrared photons. In addition, it is worth noting that the double doping of some rare-earth ions can further improve the overall PLQY of the CsPbCl 3 single crystal. Among them, Ce 3+ -Yb 3+ co-doped CsPbCl 3The PLQY of the single crystal bulk reached 177.3%, mainly due to Ce 3+ -Yb 3+ ions, as a typical and effective quantum cutting luminescent ion pair, can compensate for the mismatch problem between CsPbCl 3 and Yb 3+ energy transfer, thereby improving the PLQY of near-infrared quantum cutting luminescence. At the same time, Ce 3+ itself has 4f-5d energy level transitions, which can achieve UV region absorption, and then enhance the overall absorption ability of CsPb 0.8 Yb 0.15 Ce 0.05 Cl 3 single crystal in the UV region.

[0128] Figure 12 It is the scintillation performance characterization spectrogram of the rare earth doped perovskite single crystal material obtained in Example 7, where Figure 12 a is the fluorescence spectrum of the LYSO crystal under X-ray irradiation, Figure 12 b of 0.85 Yb 0.15 Cl 1.5 Br 1.5 is the fluorescence intensity comparison chart of the CsPb Figure 12 c of 0.85 Yb 0.15 Cl 1.5 Br 1.5 single crystal and other scintillators, Figure 12 d of 0.85 Yb 0.15 Cl 1.5 Br 1.5 is the signal-to-noise ratio of the CsPb Figure 12 single crystal depending on the X-ray dose rate; it can be seen from 0.85 Yb 0.15 Cl 1.5 Br 1.5 that the CsPb

[0129] single crystal has excellent scintillation performance, and the light yield of its scintillator is better than that of most reported materials. Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, not all embodiments. Other embodiments can be obtained according to this embodiment without creative efforts, and these embodiments all belong to the protection scope of the present invention.

Claims

1. A rare earth doped perovskite single crystal material, characterized in that: The chemical composition of the rare earth doped perovskite single crystal material is CsB 1-y-z Yb y RE z X3, wherein B is Pb and / or Cd, X is Br and / or Cl, RE is a rare earth element other than Yb, y is in the range of 0.05 to 0.25, and z is in the range of 0 to 0.

20.

2. The rare earth doped perovskite single crystal material according to claim 1, characterized in that: The RE is at least one of Sm, Dy, Tb, Pr, Ce, Nd and Er.

3. The method for preparing the rare earth-doped perovskite single crystal material according to claim 1 or 2, characterized in that: When X is Br or Cl, it is recorded as Preparation Method 1, and the Preparation Method 1 comprises the following steps: After mixing a B source, rare earth acetate, a cesium source and a hydrohalic acid, a hydrothermal reaction and a cooling treatment are sequentially performed to obtain the rare earth-doped perovskite single crystal material; the hydrohalic acid includes hydrochloric acid or hydrobromic acid; the rare earth acetate includes ytterbium acetate and RE-containing acetate; When X is Br and Cl, it is recorded as Preparation Method 2, and the Preparation Method 2 comprises the following steps: Firstly mixing a B source, a cesium source, rare earth acetate and hydrochloric acid to obtain a chlorine-containing precursor solution; The B source, the cesium source, the rare earth acetate and the hydrobromic acid are mixed to obtain a bromine-containing precursor solution; After mixing the chlorine-containing precursor solution and the bromine-containing precursor solution, performing a hydrothermal reaction and a cooling treatment in sequence to obtain the rare earth-doped perovskite single crystal material; The rare earth acetate includes ytterbium acetate and RE-containing acetate.

4. The preparation method according to claim 3, characterized in that: The B source includes acetate, and the acetate includes lead acetate and / or cadmium acetate; the cesium source includes cesium acetate.

5. The preparation method according to claim 3 or 4, characterized in that: The amount of ytterbium acetate is 5-25% of the amount of source B; The amount of the substance containing RE acetate is 0 to 20% of the amount of the substance of source B; Calculated by the amount of the element, the molar ratio of the B source to the cesium source is 1-yz:1, wherein the value range of y is 0.05 to 0.25, and the value range of z is 0 to 0.20; In the preparation method 1, the concentration of the hydrochloric acid is 35-37 wt%, the concentration of the hydrobromic acid is 48 wt%; the usage ratio of the B source and the hydrohalic acid is 1 mmol:12 mL; In the preparation method 2, the concentration of the hydrochloric acid is 35-37wt%, and the concentration of the hydrobromic acid is 48wt%; the usage ratio of the B source and the hydrochloric acid is 1mmol:12mL, and the usage ratio of the B source and the hydrobromic acid is 1mmol:12mL; the volume ratio of the chlorine-containing precursor solution and the bromine-containing precursor solution is 1-11:1-11, and the total volume of the chlorine-containing precursor solution and the bromine-containing precursor solution is 12mL.

6. The preparation method according to claim 3, characterized in that: The temperature of the hydrothermal reaction is 200-240° C., and the insulation time is 12-24 hours.

7. The preparation method according to claim 3, characterized in that: The cooling rate of the cooling treatment is 2-4°C / min.

8. Use of the rare earth-doped perovskite single crystal material according to claim 1 or 2 or the rare earth-doped perovskite single crystal material prepared by the preparation method according to any one of claims 3 to 7 as a scintillator material in a detector.

9. An indirect X-ray detector, characterized in that: The invention comprises a SiPM substrate and a detector material located on the surface of the SiPM substrate, wherein the detector material is the rare earth doped perovskite single crystal material according to claim 1 or 2 or the rare earth doped perovskite single crystal material prepared by the preparation method according to any one of claims 3 to 7.

10. The method for preparing an indirect X-ray detector according to claim 9, characterized in that: The following steps are involved: The detector material is fixed on the surface of the SiPM substrate by UV curing glue.

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