A method for preparing FAPbBr3 heterocrystalline material with low and stable dark current and its application.

Abstract

This invention discloses a method for preparing FAPbBr3 heterojunctions with low and stable dark current and their applications, relating to the field of semiconductor heterojunction technology. The method includes preparing a FAPbBr3 single crystal; dissolving FABr, PbBr2, and PbCl2 in an organic solvent to obtain an epitaxial layer precursor solution; filtering the epitaxial layer precursor solution to obtain a filtrate; sealing the filtrate and placing it in a water bath, heating it to 33-36°C, then adding the FAPbBr3 single crystal, continuing to seal and heating to 43-46°C, to obtain a FAPbBr3 heterojunction with low and stable dark current. This invention effectively suppresses dark current in heterojunction epitaxial growth processes targeting FAPbBr3 single crystals, thereby obtaining radiation detection devices with good radiation detection performance for both X-rays and alpha particles.

Description

Technical Field

[0001] This invention relates to the field of semiconductor heterojunction technology, specifically to a method for preparing FAPbBr3 heterojunction with low and stable dark current and its application. Background Technology

[0002] Radiation detection plays an indispensable role in various fields such as medical diagnostics and security inspection. In recent years, organic-inorganic halide perovskites have demonstrated outstanding performance in radiation detection applications due to their excellent photoelectric properties, high tolerance to defects, tunable band gaps, and ease of synthesis. Among various halide perovskite materials, three-dimensional FAPbBr3 has made significant progress in radiation detection due to its structural stability and thermal stability at room temperature, gradually attracting widespread attention. However, the low bulk resistivity and high dark current in perovskite crystal detectors remain major challenges.

[0003] To meet the requirements of perovskite detectors operating at high bias voltages and exhibiting low dark current, and to achieve high-efficiency radiation detection performance, it is urgent to adopt device structures capable of suppressing dark current. Introducing junction structures into single crystals has become a promising approach. In addition to using asymmetric metal electrodes, it is also possible to consider constructing suitable epitaxial layers on single crystals to form heterojunction structures, thereby improving carrier transport efficiency and effectively reducing dark current.

[0004] As is well known, heterojunctions not only increase the resistivity of semiconductor materials but also effectively reduce the dark current in optoelectronic devices. The potential difference across a heterojunction creates an internal electric field, which facilitates the rapid separation of photogenerated carriers. Compared to MAPbBr3-based heterojunctions, FAPbBr3-based heterojunctions have greater advantages in terms of structure, thermal stability, and carrier transport performance, thus theoretically possessing superior radiation detection potential. Therefore, constructing heterojunction structures using FAPbBr3 crystals to further enhance radiation detection capabilities is an important research direction in halide perovskite studies.

[0005] Liquid phase epitaxy is simple and easy to operate, and has low growth cost. However, in the current research on the preparation of FAPbBr3 epitaxial heterojunctions, the following problems still exist: (1) The concentration of the precursor solution and the heating curve during the epitaxy process are still unclear. If the heating program is not set properly, the seed crystal may be completely dissolved during the epitaxy process. At the same time, the heating rate and the composition of the epitaxial layer will also affect whether the heterojunction interface is tight and defect-free. Defects such as pores or cracks will affect the performance of the heterojunction. (2) Compared with MAPbBr3 perovskite crystals, FAPbBr3 crystals are more likely to generate a second phase during the growth process. It is necessary to set an appropriate growth time to ensure that the epitaxial heterojunction is obtained before the second phase appears. Summary of the Invention

[0006] To address the shortcomings of the aforementioned background technology, this invention primarily solves the problem of unstable dark current in FAPbBr3 single-crystal perovskite radiation detectors. This invention provides a method for preparing FAPbBr3 heterojunctions with low and stable dark current, and its application. This method is low-cost, short-cycle, simple to operate, and effectively suppresses dark current in the heterojunction epitaxial growth process of FAPbBr3 single crystals, thereby obtaining radiation detectors with good radiation detection performance for both X-rays and alpha particles.

[0007] The first objective of this invention is to provide a method for preparing FAPbBr3 heterocrystalline material with low and stable dark current, comprising the following steps:

[0008] Preparation of FAPbBr3 single crystals;

[0009] FABr, PbBr2, and PbCl2 were dissolved in an organic solvent to obtain an epitaxial layer precursor solution;

[0010] The epitaxial layer precursor solution was filtered to obtain the filtrate;

[0011] After sealing the filtrate, place it in a water bath and heat it to 33~36℃. Then add FAPbBr3 single crystals, continue to seal and heat to 43~46℃ to obtain FAPbBr3 heterocrystalline material with low and stable dark current.

[0012] Preferably, after adding FAPbBr3 single crystal, the temperature is kept constant at 33~36℃ for 1~2 hours.

[0013] Preferably, the continued sealing and heating to 43~46℃ is initiated at a heating rate of 0.6~0.8℃ / h to reach 43~46℃.

[0014] Preferably, the molar ratio of FABr to PbBr2+PbCl2 is 1:1;

[0015] The molar ratio of PbBr2 to PbCl2 is (0.8~0.95):(0.05~0.2).

[0016] Preferably, the organic solvent is N,N dimethylformamide and γ-valerolactone in a volume ratio of 1:0.8~1.

[0017] Preferably, the FAPbBr3 single crystal is prepared according to the following steps:

[0018] FABr and PbBr2 were dissolved in a mixed solvent of N,N dimethylformamide (DMF) and γ-valerol (GVL) to obtain a precursor solution. The precursor solution was filtered, the filtrate was collected, and the flask was sealed with an Erlenmeyer flask. The flask was then placed in a water tank with the mouth of the flask above the water surface, ensuring that all the precursor solution was submerged in the water. The temperature was increased from room temperature to 45-50°C at a rate of 3-5°C / day to precipitate crystals. After the crystals precipitated, they were removed, washed, and dried to obtain FAPbBr3 single crystals.

[0019] Preferably, the FABr is prepared by mixing formamidine acetate with hydrobromic acid and distilling at 80°C.

[0020] The second objective of this invention is to provide a FAPbBr3 heterocrystalline material with low and stable dark current.

[0021] A third objective of this invention is to provide an application of FAPbBr3 heterojunction with low and stable dark current in radiation detection devices.

[0022] A fourth objective of this invention is to provide a radiation detector comprising a FAPbBr3 heterostructure and gold electrodes deposited on both sides of the FAPbBr3 heterostructure.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] This invention provides a method for preparing FAPbBr3 heterojunctions with low and stable dark current and their applications. This invention utilizes a seed-based liquid-phase epitaxy combined with inverse-temperature crystallization to prepare FAPbBr3-based perovskite heterojunctions for the first time. By precisely controlling the heating rate during the simple and low-cost liquid-phase epitaxy process, a smooth and defect-free substrate is formed at the seed crystal interface, resulting in a compact and pore-free heterojunction interface. The FAPbBr3-based heterojunctions prepared by this method have beneficial effects such as reducing the dark current of photodetectors, maintaining a stable dark current level, improving charge separation efficiency in photoelectric materials, and thus improving radiation detection efficiency. Attached Figure Description

[0025] Figure 1 The FAPbBr3 / FAPbBr grown in Example 1 2.9 Cl 0.1 Single crystal;

[0026] Figure 2 The FAPbBr3 / FAPbBr grown in Example 2 2.6 Cl 0.4 Single crystal;

[0027] Figure 3 This is a FAPbBr3 single crystal grown in Comparative Example 1;

[0028] Figure 4 The dark current-voltage curves for Example 1 are shown from -100V to +100V.

[0029] Figure 5 The dark current-voltage curves for Example 2 are shown from -100V to +100V.

[0030] Figure 6 The dark current-voltage curve for Comparative Example 1 is shown from -100V to +100V.

[0031] Figure 7 Au / FAPbBr3 / FAPbBr prepared in Example 2 2.6 Cl 0.4 / Au detector's X-ray response sensitivity and alpha particle response energy spectrum, where a~c are variable-dosage X-ray sources, and d is 241 Am particle source.

[0032] Figure 8 The X-ray response of the Au / FAPbBr3 / Au detector prepared for Comparative Example 1. Detailed Implementation

[0033] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0034] The purpose of this invention is to provide a method for preparing FAPbBr3 heterojunctions with low and stable dark current and their applications, thereby solving the problem of unstable dark current in FAPbBr3 single-crystal perovskite radiation detectors. This invention provides a low-cost, short-cycle, simple-to-operate heterojunction epitaxial growth process for FAPbBr3 single crystals that effectively suppresses dark current, thus obtaining radiation detectors with good radiation detection performance for both X-rays and alpha particles.

[0035] To achieve the above objectives, a first aspect of the present invention provides a method for preparing FAPbBr3 heterocrystalline material with low and stable dark current, comprising the following steps:

[0036] Preparation of FAPbBr3 single crystals;

[0037] FABr, PbBr2, and PbCl2 were dissolved in an organic solvent to obtain an epitaxial layer precursor solution;

[0038] The epitaxial layer precursor solution was filtered to obtain the filtrate;

[0039] After sealing the filtrate, place it in a water bath and heat it to 33~36℃. Then add FAPbBr3 single crystals, continue to seal and heat to 43~46℃ to obtain FAPbBr3 heterocrystalline material with low and stable dark current.

[0040] Among them, after adding FAPbBr3 single crystal, the temperature was kept constant at 33~36℃ for 1~2 hours.

[0041] The process of continuing to seal and heat to 43~46℃ involves starting the heating at a rate of 0.6~0.8℃ / h to reach 43~46℃.

[0042] The molar ratio of FABr to PbBr2+PbCl2 is 1:1;

[0043] The molar ratio of PbBr2 to PbCl2 is (0.8~0.95):(0.05~0.2).

[0044] The organic solvent is N,N dimethylformamide and γ-valerolactone in a volume ratio of 1:0.8~1.

[0045] The FAPbBr3 single crystal was prepared according to the following steps:

[0046] FABr and PbBr2 were dissolved in a mixed solvent of N,N dimethylformamide (DMF) and γ-valerol (GVL) to obtain a precursor solution. The precursor solution was filtered, the filtrate was collected, and the flask was sealed with an Erlenmeyer flask. The flask was then placed in a water tank with the mouth of the flask above the water surface, ensuring that all the precursor solution was submerged in the water. The temperature was increased from room temperature to 45-50°C at a rate of 3-5°C / day to precipitate crystals. After the crystals precipitated, they were removed, washed, and dried to obtain FAPbBr3 single crystals.

[0047] The FABr is prepared by mixing formamidine acetate with hydrobromic acid and distilling at 80°C.

[0048] A second aspect of the present invention provides a FAPbBr3 heterocrystalline material having low and stable dark current.

[0049] A third aspect of the present invention provides the application of FAPbBr3 heterojunction with low and stable dark current in radiation detection devices.

[0050] A fourth aspect of the present invention provides a radiation detector comprising a FAPbBr3 heterostructure and gold electrodes deposited on both sides of the FAPbBr3 heterostructure.

[0051] In one embodiment, a method for preparing a low and stable dark current FAPbBr3 heterocrystalline material includes the following steps:

[0052] S1. Prepare precursor compounds:

[0053] Formamidine acetate and 48% hydrobromic acid by mass were mixed and distilled at 80°C to obtain the FABr compound.

[0054] The mixture contained 40g of formamidine acetate and 45mL of hydrobromic acid, with a molar ratio of 1:1.

[0055] S2. Prepare the precursor solution:

[0056] FABr, PbBr2, NN dimethylformamide (DMF) and γ-valerol (GVL) were mixed to obtain a precursor solution;

[0057] The molar ratio of FABr to PbBr2 is 1:1, the volume ratio of organic solvent DMF to GVL is 1:0.8, and the molar concentration of solute is 1.2~1.55 mol / L, preferably 1.4 mol / L.

[0058] S3. Obtain seed crystals:

[0059] The nearly saturated solution obtained from S2 was filtered, the filtrate was collected, and the mouth of the filtrate was sealed with an Erlenmeyer flask. Then it was placed in a temperature-controlled water tank at 30~50℃ with the mouth of the flask protruding above the water surface to ensure that all precursor solutions were submerged in the water in the tank for heating.

[0060] The typical heating procedure starts at room temperature and increases the temperature at a rate of 3-5°C / day to 45-50°C to precipitate crystals.

[0061] After the crystals precipitate, remove them, wash and dry them to obtain high-quality FAPbBr3 single crystals.

[0062] S4. Liquid-phase epitaxial precursor solution:

[0063] FABr, PbBr2, PbCl2, N,N dimethylformamide (DMF) and γ-valerol (GVL) were mixed to obtain an epitaxial layer precursor solution;

[0064] The molar ratio of FABr to (PbBr2+PbCl2) is 1:1, and the volume ratio of organic solvent DMF to GVL is 1:0.8.

[0065] The FAPbBr3 / FAPbBr prepared here 3-x Cl x The x-value of the heterojunction is 0.1 or 0.4, where FAPbBr3 / FAPbBr 2.9 Cl 0.1 The molar ratio of PbBr2 to PbCl2 in the precursor solution was 0.95:0.05; FAPbBr3 / FAPbBr2.6 Cl 0.4 The molar ratio of PbBr2 to PbCl2 in the precursor solution is 0.8:0.2.

[0066] S5. Preparation of heterojunctions:

[0067] The nearly saturated solution obtained from S4 was filtered, the filtrate was collected, and the mouth of the filtrate was sealed with an Erlenmeyer flask. Then it was placed in a temperature-controlled water tank at 30~50℃ with the mouth of the flask protruding above the water surface to ensure that all precursor solutions were submerged in the water in the tank for heating.

[0068] When the temperature rises to 33~36℃, the FAPbBr3 single crystal obtained by S3 is placed in the epitaxial layer precursor solution as a seed crystal. Then, the conical flask is sealed and placed in the water tank. Before continuing to heat up, the temperature is kept constant at 33~36℃ for 2 hours to allow the seed crystal to dissolve back.

[0069] Starting from 38℃, the temperature is increased at a rate of 0.6~0.8℃ / h to precipitate the epitaxial layer;

[0070] After the epitaxial layer precipitates at approximately 45°C, the heterocrystalline material is removed, washed, and dried to obtain high-quality FAPbBr3 / FAPbBr. 3-x Cl x Single crystal;

[0071] The purpose of heating the epitaxial precursor solution from room temperature to 33-36°C is to reduce the dissolution of the seed crystal in the precursor solution and prevent the seed crystal from being completely dissolved. The purpose of performing a isothermal program before heating is to ensure that a small amount of the seed crystal surface is dissolved so that a smooth and defect-free substrate can be obtained before the epitaxial layer grows. In order to avoid the precipitation of the FAPbBr3 second phase, the epitaxial layer growth is controlled within 10 hours.

[0072] In S3, the crystals are washed with ethanol or DMF and then dried in a vacuum drying oven.

[0073] In S3 and S5, the obtained near-saturated solutions were filtered using organic filters with pore sizes of 0.22–0.45 μm.

[0074] According to the present invention, it further includes:

[0075] S6. Heterogeneous crystal cutting:

[0076] Since both the seed crystal and the epitaxial layer are three-dimensional crystals, the epitaxial layer will grow around the entire seed crystal. After the heterocrystalline material is removed, the epitaxial layer around the seed crystal needs to be cut to leave only the (001) plane epitaxial layer.

[0077] The purpose of cutting around the seed crystal is to ensure a heterojunction of the single-junction type.

[0078] S7. Crystal grinding and polishing:

[0079] For the growth of FAPbBr3 / FAPbBr 3-x Cl x The single-crystal heterojunction was physically polished using 5000-7000 grit sandpaper, and then the FAPbBr3 / FAPbBr... 3-x Cl x Transfer the single crystal onto the polishing cloth and add 3-5 drops of polishing solution for chemical polishing.

[0080] S8. Electrode fabrication:

[0081] Gold electrodes were deposited on both sides of the polished heterocrystalline material to obtain Au / FAPbBr3 / FAPbBr. 3-x Cl x / Au sandwich-type heterojunction radiation detector.

[0082] In S6, a diamond wire cutter is used to cut heterogeneous crystals.

[0083] In S7, the polishing solution is ethanol.

[0084] It should be noted that, unless otherwise specified, the experimental methods used in this invention are all conventional methods; and the reagents and materials used, unless otherwise specified, are all commercially available.

[0085] Example 1

[0086] A method for preparing low and stable dark current FAPbBr3 heterocrystalline material, comprising the following steps:

[0087] 1) At room temperature, 0.018 mol FABr, 0.018 mol PbBr2, 7.5 mL NN dimethylformamide (DMF), and 7.5 mL γ-valerol (GVL) were mixed to obtain a precursor solution;

[0088] 2) Filter the above solution into an Erlenmeyer flask using a Buchner funnel and 0.22 μm organic filter paper, and seal the flask with plastic wrap and a rubber stopper.

[0089] 3) Place the conical flask with its mouth above the water surface into the water tank, and start heating from room temperature at a rate of 4℃ / day. The crystals will gradually nucleate and grow in the solution. Once the temperature reaches 47℃, remove the FAPbBr3 crystals.

[0090] 4) Wash the FAPbBr3 crystals with DMF and dry them in a vacuum drying oven for later use.

[0091] 5) At room temperature, 0.0165 mol FABr, 0.015675 mol PbBr2, 0.000825 mol PbCl2, 7.5 mL of NN dimethylformamide (DMF) and 7.5 mL of γ-valerol (GVL) were mixed to obtain an epitaxial layer precursor solution.

[0092] 6) Filter the above solution into an Erlenmeyer flask using a Buchner funnel and 0.22 μm organic filter paper. Seal the flask with plastic wrap and a rubber stopper and place it in a water tank for heating. When the temperature reaches 35°C, remove the Erlenmeyer flask and place the FAPbBr3 crystal inside. After placing the seed crystal, seal the flask with plastic wrap and a rubber stopper and place it in the water tank to continue the heating process. The epitaxial layer will gradually grow on the surface of the seed crystal. Remove the heterocrystalline material when the temperature reaches about 47°C.

[0093] 7) Retain the (001) crystal plane of the heterostructure, cut the remaining epitaxial layers, and then process the grown FAPbBr3 / FAPbBr... 2.9 Cl 0.1 The single-crystal heterojunction was polished and then Au electrodes were deposited on both the top and bottom surfaces to obtain Au / FAPbBr3 / FAPbBr. 2.9 Cl 0.1 / Au detector.

[0094] Example 2

[0095] A method for preparing low and stable dark current FAPbBr3 heterocrystalline material, comprising the following steps:

[0096] 1) At room temperature, 0.02325 mol FABr, 0.02325 mol PbBr2, 7.5 mL NN dimethylformamide (DMF), and 7.5 mL γ-valerol (GVL) were mixed to obtain a precursor solution;

[0097] 2) Filter the above solution into an Erlenmeyer flask using a Buchner funnel and 0.22 μm organic filter paper, and seal the flask with plastic wrap and a rubber stopper.

[0098] 3) Place the conical flask with its mouth above the water surface into the water tank, start heating from room temperature, and begin heating at a rate of 4℃ / day. The crystals will gradually nucleate and grow in the solution. Once the temperature reaches about 48℃, remove the crystals.

[0099] 4) Wash the crystals with DMF and dry them in a vacuum drying oven for later use.

[0100] 5) At room temperature, 0.021 mol FABr, 0.0168 mol PbBr2, 0.0042 mol PbCl2, 7.5 mL of NN dimethylformamide (DMF) and 7.5 mL of γ-valerol (GVL) were mixed to obtain an epitaxial layer precursor solution.

[0101] 6) Filter the above solution into an Erlenmeyer flask using a Buchner funnel and 0.22 μm organic filter paper. Seal the flask with plastic wrap and a rubber stopper and place it in a water tank for heating. When the temperature reaches 35°C, remove the Erlenmeyer flask and place the FAPbBr3 crystal inside. After placing the seed crystal, seal the flask with plastic wrap and a rubber stopper and place it in the water tank to continue the heating process. The epitaxial layer will gradually grow on the surface of the seed crystal. When the temperature reaches about 43°C, remove the heterocrystalline material.

[0102] 7) Retain the (001) crystal plane of the heterostructure, cut the remaining epitaxial layers, and then process the grown FAPbBr3 / FAPbBr... 2.6 Cl 0.4 The single-crystal heterojunction was polished and then Au electrodes were deposited on both the top and bottom surfaces to obtain Au / FAPbBr3 / FAPbBr. 2.6 Cl 0.4 / Au detector, and then X-ray and alpha particle radiation detection performance tests.

[0103] Comparative Example 1

[0104] The preparation method of FAPbBr3 single crystal is as follows:

[0105] 1) At room temperature, 0.021 mol FABr, 0.021 mol PbBr2, 7.5 mL NN dimethylformamide (DMF), and 7.5 mL γ-valerol (GVL) were mixed to obtain a precursor solution;

[0106] 2) Filter the above solution into an Erlenmeyer flask using a Buchner funnel and 0.22 μm organic filter paper, and seal the flask with plastic wrap and a rubber stopper.

[0107] 3) Place the conical flask with its mouth above the water surface into the water tank, start heating from room temperature, and begin heating at a rate of 4℃ / day. The crystals will gradually nucleate and grow in the solution. Once the temperature reaches about 49℃, remove the crystals.

[0108] 4) The grown FAPbBr3 single crystal is polished and Au electrodes are deposited on both the top and bottom surfaces to obtain an Au / FAPbBr3 / Au detector.

[0109] To illustrate the relevant properties of the heterocrystalline material provided by this invention, the accompanying drawings are provided.

[0110] Figure 1 The FAPbBr3 / FAPbBr grown in Example 1 2.9 Cl 0.1 Single crystal;

[0111] from Figure 1 It can be seen that the size of the seed crystal is 2×2 ~ 4×4 mm. 2Furthermore, the epitaxial layer can be seen surrounding the seed crystal and maintaining its shape. Because the composition of the epitaxial layer is only slightly different from that of the seed crystal, their colors are almost identical. Since the temperature at which it was removed was 47℃, the epitaxial layer growth time was relatively long, resulting in a thicker epitaxial layer.

[0112] Figure 2 The FAPbBr3 / FAPbBr grown in Example 2 2.6 Cl 0.4 Single crystal;

[0113] from Figure 2 It can be seen that the size of the seed crystal is 4×4 ~ 5×5 mm. 2 Furthermore, a clear boundary between the seed crystal and the epitaxial layer can be observed. The epitaxial layer surrounds the seed crystal and maintains its shape. The Cl concentration in the epitaxial layer is significantly increased, resulting in a noticeable yellowing color. Moreover, the epitaxial layer was removed at 43℃, indicating a relatively short growth time and a thinner epitaxial layer.

[0114] Figure 3 This is a FAPbBr3 single crystal grown in Comparative Example 1;

[0115] from Figure 3 It can be seen that the size of the grown single crystal is approximately 4×4 ~ 5×5 mm. 2 The fact that a single crystal is transparent, defect-free, and cubic in shape indicates that it has good crystallization quality.

[0116] Figure 4 The dark current-voltage curves for Example 1 are shown from -100V to +100V. Figure 5 The dark current-voltage curves for Example 2 are shown from -100V to +100V.

[0117] from Figures 4-5 It is evident that the negative voltage region has a significant effect on suppressing dark current. In the case of fabricating a heterojunction, fabricating Au electrodes on both sides of the heterojunction single crystal yields a distinct junction current-voltage curve, meaning that the current is cut off in the reverse-biased (negative voltage) region. The dark current in the negative voltage region is not only significantly reduced but can also maintain a stable low value over a wide negative voltage range, indicating that this is an effective method for obtaining low and stable dark current.

[0118] Figure 6 The dark current-voltage curve for Comparative Example 1 is shown from -100V to +100V. Figure 6 It can be seen that the dark current density value at -100 V is significantly higher than that in Examples 1 and 2.

[0119] from Figure 6It can be seen that without the preparation of a heterojunction, the preparation of Au electrodes on both sides of the FAPbBr3 single crystal will yield a typical ohmic current-voltage curve, while the dark current at -100V is reduced by about 5 times before and after the preparation of the heterojunction on the same sample.

[0120] Figure 7 Au / FAPbBr3 / FAPbBr prepared in Example 2 2.6 Cl 0.4 / Au detector's X-ray response sensitivity and alpha particle response energy spectrum, where a~c are variable-dosage X-ray sources, and d is 241 Am particle source.

[0121] from Figure 7 It can be seen that in the On / Off current-time curve under X-ray irradiation, when the X-ray source is periodically turned off, the dark current of the device can still fall back to the level before the X-ray irradiation begins, and it remains stable during this process. At the same time, thanks to the low and stable dark current brought about by the heterojunction preparation, the X-ray detection response sensitivity is significantly increased. Furthermore, by replacing the radiation source with alpha particles, an alpha particle response energy spectrum with good peak shape and symmetrical Gaussian shape can be obtained.

[0122] Figure 8 The X-ray response of the Au / FAPbBr3 / Au detector prepared for Comparative Example 1;

[0123] from Figure 8 It is known that FAPbBr3 single crystals have a very weak X-ray response and cannot maintain their dark current level under an applied bias voltage; instead, it gradually changes over time. Under these circumstances, not only is a good X-ray response impossible to obtain, but it is also impossible to measure the radiation detection performance of any other radiation source.

[0124] This invention describes preferred embodiments and their effects. However, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to include both the preferred embodiments and all changes and modifications falling within the scope of this invention.

[0125] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing FAPbBr3 heterocrystalline material with low and stable dark current, characterized in that, Includes the following steps: Preparation of FAPbBr3 single crystals; FABr, PbBr2, and PbCl2 were dissolved in an organic solvent to obtain an epitaxial layer precursor solution; The epitaxial layer precursor solution was filtered to obtain the filtrate; After sealing the filtrate, place it in a water bath and heat it to 33~36℃. Then add FAPbBr3 single crystals, continue to seal and heat to 43~46℃ to obtain FAPbBr3 heterocrystalline material with low and stable dark current. After adding FAPbBr3 single crystal, maintain a constant temperature of 33~36℃ for 1~2 hours; The process of continuing to seal and heat to 43~46℃ is to start heating to 43~46℃ at a heating rate of 0.6~0.8℃ / h. The molar ratio of FABr to PbBr2+PbCl2 is 1:1; The molar ratio of PbBr2 to PbCl2 is (0.8~0.95):(0.05~0.2). The organic solvent is N,N dimethylformamide and γ-valerol in a volume ratio of 1:0.8~1; The FAPbBr3 single crystal was prepared according to the following steps: FABr and PbBr2 were dissolved in a mixed solvent of N,N dimethylformamide (DMF) and γ-valerol (GVL) to obtain a precursor solution. The precursor solution was filtered, the filtrate was collected, and the flask was sealed with an Erlenmeyer flask. The flask was then placed in a water tank with the mouth of the flask above the water surface, ensuring that all the precursor solution was submerged in the water. The temperature was increased from room temperature to 45-50°C at a rate of 3-5°C / day to precipitate crystals. After the crystals precipitated, they were removed, washed, and dried to obtain FAPbBr3 single crystals. The FABr is prepared by mixing formamidine acetate with hydrobromic acid and distilling at 80°C.

2. A FAPbBr3 heterocrystalline material with low and stable dark current prepared by the method of claim 1.

3. The application of the FAPbBr3 heterojunction with low and stable dark current as described in claim 2 in radiation detection devices.

4. A radiation detector, characterized in that, It includes the FAPbBr3 heterocrystalline material as described in claim 2, and gold electrodes deposited on both sides of the FAPbBr3 heterocrystalline material.

Images