A two-dimensional perovskite single crystal, an X-ray detector and a preparation method thereof

Abstract

The application provides a kind of two-dimensional perovskite single crystal of double amine and X-ray detector and preparation method thereof, two-dimensional perovskite single crystal of double amine is expressed as ABX4, A is dimethyl guanidine or dicyan diamine, B is Pb 2+ Or Sn 2+ ;X is Cl ‑ , Br ‑ Or I ‑ . The organic component in the two-dimensional perovskite single crystal of the application selects the double amine type A site molecule, the double amine type A site molecule contains various functional groups such as electron-rich amine, imine and electron-poor amine group, can form strong interaction with BX4 octahedron, improve perovskite lattice stiffness, reduce electron-phonon coupling and lattice distortion, make two-dimensional perovskite single crystal have high carrier mobility, be conducive to realizing higher X-ray sensitivity.

Description

Technical Field

[0001] This invention belongs to the field of single crystal synthesis and X-ray detection technology, specifically relating to a diamine two-dimensional perovskite single crystal, its X-ray detector, and preparation method. Background Technology

[0002] Two-dimensional (2D) organic-inorganic hybrid perovskite single crystals (PSCs) combine the performance advantages of both inorganic and organic components, exhibiting a rich variety of crystal structures, optical and electrical properties, and showing great application potential in devices such as radiation (X-ray) detectors, photodetectors, and solar cells. Particularly in X-ray detection, 2D PSCs possess large X-ray absorption coefficients, high bulk resistivity and ion migration activation energy, strong self-defect states, excellent operational stability, and low cost, making them considered one of the best candidate materials for next-generation X-ray detectors, applicable to industrial fields such as medical diagnostics, non-destructive testing, and security inspection. Two-dimensional halide perovskites are formed by cutting along specific crystal planes of the three-dimensional perovskite structure. Typical 2D PSCs are the Ruddlesden-Popper (RP) type and the Dion-Jacobson (DJ) type. For 2D perovskites with n=1, RP and DJ can adopt the general structural formulas A'2MX4 and A"MX4, respectively, where A' is a monovalent (+1) organic cation and A" is a divalent (+2) organic cation. The natural quantum well structure also endows these perovskites with anisotropic carrier transport properties, namely restricted out-of-plane carrier transport and favorable in-plane carrier transport. The performance of X-ray detectors is closely related to carrier mobility; however, current X-ray detectors based on two-dimensional materials exhibit low sensitivity due to their relatively low carrier mobility. Therefore, developing novel 2D perovskite materials with high carrier mobility and higher sensitivity to X-rays is urgent and necessary. Summary of the Invention

[0003] In order to overcome the shortcomings of existing technologies for X-ray detection of two-dimensional perovskite single crystals, the purpose of this invention is:

[0004] Firstly, a method for preparing a diamine two-dimensional perovskite single crystal ABX4 is provided, which enhances the lattice stiffness of the two-dimensional perovskite by using dimethyl biguanide or dicyandiamine, suppresses electron-phonon coupling, and improves carrier mobility.

[0005] Secondly, an X-ray detector based on the above-mentioned diamine two-dimensional perovskite single crystal and its preparation method are provided, achieving the best detection sensitivity of two-dimensional perovskite single crystal to date.

[0006] This invention is achieved through the following technical solution:

[0007] A two-dimensional perovskite single crystal with a diamine, denoted as ABX4, where A is dimethyl biguanide (DGA) or dicyandiamide (DCDA), and B is Pb. 2+ or Sn 2+ X is Cl - ,Br - Or I - .

[0008] The method for preparing the diamine two-dimensional perovskite single crystal includes the following steps:

[0009] Step 1: Take dimethyl biguanide and BO, or take dicyandiamine and BO, dissolve them in an acidic aqueous solution, add hypophosphoric acid to obtain a mixed precursor solution, stir and heat to 90-115°C until the solution is transparent, filter to obtain a saturated precursor solution; wherein, the BO is PbO or SnO.

[0010] Step 2: Seal the saturated precursor solution and keep it at 95-120℃ for 2-3 hours to obtain the crystallized solution;

[0011] Step 3: Cool the crystallized solution to room temperature at a rate of 0.5–2 °C / h, filter, and obtain a two-dimensional perovskite single crystal seed crystal; place the defect-free two-dimensional perovskite single crystal seed crystal in a new precursor saturated solution, seal the precursor saturated solution and keep it at 95–120 °C for 2–3 h, and then cool it to room temperature at a rate of 1–5 °C / day to obtain a centimeter-sized diamine two-dimensional perovskite single crystal;

[0012] Step 4: Clean and dry the centimeter-sized diamine two-dimensional perovskite single crystal to obtain the diamine two-dimensional perovskite single crystal.

[0013] Preferably, in step 1, the molar ratio of dimethyl biguanide or dicyandiamide to BO is 1:1.

[0014] Preferably, in step 1, the acidic aqueous solution solvent is at least one of HI acid, HBr acid, and HCl acid.

[0015] Preferably, in step 2, the sealing material is 5 to 20 layers of polyethylene, polyvinyl chloride, or polyvinylidene chloride plastic wrap and high-temperature tape.

[0016] Preferably, in step 4, the organic reagent used for cleaning is anhydrous diethyl ether, isopropanol, acetonitrile, methanol, or chloroform.

[0017] An X-ray detector includes a light-absorbing layer and an electrode disposed on one side surface of the light-absorbing layer; the light-absorbing layer is the aforementioned diamine two-dimensional perovskite single crystal.

[0018] Preferably, the electrode is a metal interdigitated electrode or a carbon electrode.

[0019] The method for fabricating the X-ray detector includes:

[0020] Step 1) Physically polish the surface of the diamine two-dimensional perovskite single crystal;

[0021] Step 2) An electrode is prepared on the surface of a physically polished two-dimensional perovskite single crystal.

[0022] Preferably, in step 1), the mesh size selected for physical polishing is 2000 to 10000 mesh.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] In this invention, the organic component in the diamine-type two-dimensional perovskite single crystal is selected from diamine-type A-site molecules such as dimethylbiguanide or dicyandiamine. These molecules contain various functional groups, including electron-rich amines, imines, and electron-depleted amines, which can form strong interactions with the inorganic component BX4 octahedron, thereby increasing the perovskite lattice stiffness, reducing electron-phonon coupling and lattice distortion, and thus enabling the two-dimensional perovskite single crystal to possess high carrier mobility, which is beneficial for achieving higher X-ray sensitivity. The inorganic component of this invention has a high atomic number and a high X-ray absorption coefficient, which is beneficial for X-ray attenuation. This invention provides compositional design ideas for the application of two-dimensional organic-inorganic perovskites.

[0025] The method of this invention uses a seed crystal-assisted method to grow two-dimensional perovskite single crystals with diamine. Since the precursor saturated solution is sealed, the growth temperature is controlled below the boiling point of the acidic aqueous solution solvent, which effectively suppresses component deviation caused by raw material volatilization and pollution of the growth environment. Moreover, the growth rate is very slow, and large-size, high-quality two-dimensional perovskite single crystals can be obtained.

[0026] Furthermore, this invention uses multi-layered cling film and high-temperature tape for sealing, which provides a good sealing effect and can better suppress component deviation and pollution of the growth environment caused by raw material volatilization.

[0027] This invention relates to an X-ray detector based on a two-dimensional perovskite single crystal with diamine, which has higher X-ray sensitivity and X-ray attenuation efficiency. Attached Figure Description

[0028] Figure 1 These are schematic diagrams of the structure of a two-dimensional perovskite single crystal with diamine as seen along different axes.

[0029] Figure 2 This is the X-ray diffraction pattern of a two-dimensional perovskite single crystal with diamine.

[0030] Figure 3This is the steady-state absorption spectrum of a two-dimensional perovskite single crystal with diamine. The inset shows the optical band gap calculated using the Tauc-Plot method.

[0031] Figure 4 It is a function of the absorption coefficient of different materials as a function of photon energy, ranging from 10 keV to 1 MeV.

[0032] Figure 5 This describes the relationship between the attenuation efficiency of different materials for 40 keV energy rays and their thickness.

[0033] Figure 6 It is a diamine two-dimensional perovskite single-crystal X-ray detector at 967.5 μGy air s -1 It graph at different doses. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited to these embodiments. Unless otherwise specified, the methods described are conventional methods. Unless otherwise specified, the materials, instruments, and equipment described are all available from publicly available commercial sources.

[0035] The diamine two-dimensional perovskite single crystal described in this invention is ABX4, where A is dimethyl biguanide (DGA) or dicyandiamide, and B is Pb. 2 + or Sn 2+ X is Cl - ,Br - Or I - .

[0036] The method for preparing the diamine two-dimensional perovskite single crystal includes the following steps:

[0037] Step 1: Weigh dimethyl biguanide and BO, or dicyandiamine and BO, in a molar ratio of 1:1, dissolve them in an acidic aqueous solution, add 5%–15% (volume concentration of hypophosphoric acid in the acidic aqueous solution) of hypophosphoric acid to obtain a mixed precursor solution, stir and heat to 90–115°C until the solution is transparent, filter to obtain a saturated precursor solution; wherein, the BO is PbO or SnO;

[0038] Step 2: Pour the above saturated precursor solution into a crystallizing dish, seal it, and place it in an oven at 95-120°C for 2-3 hours to obtain the crystallized solution.

[0039] Step 3: The crystallized solution is gradually cooled to room temperature at a rate of 0.5-2℃ / h, filtered, and (DGA)BX4 two-dimensional perovskite single crystal seed crystal is obtained; the seed crystal without obvious defects is placed in a new saturated precursor solution, the saturated precursor solution is poured into a crystallization dish and sealed, and placed in an oven at 95-120℃ for 2-3 hours, and then gradually cooled to room temperature at a rate of 1-5℃ / day to obtain a centimeter-sized diamine two-dimensional perovskite single crystal - (DGA)BX4;

[0040] Step 4: Immerse the centimeter-sized diamine two-dimensional perovskite single crystal with an organic reagent to clean and remove impurities remaining on the surface of the diamine two-dimensional perovskite single crystal during the crystallization process. After cleaning, place it in a vacuum drying oven at 60°C to dry, and obtain the diamine two-dimensional perovskite single crystal.

[0041] In step 1, the acidic aqueous solution solvent is at least one of HI acid, HBr acid, and HCl acid. In step 2, the sealing material is 5 to 20 layers of polyethylene, polyvinyl chloride, or polyvinylidene chloride plastic wrap and high-temperature tape. In step 4, the organic reagent used is anhydrous diethyl ether, isopropanol, acetonitrile, methanol, or chloroform.

[0042] The X-ray detector based on the aforementioned bisamine two-dimensional perovskite single crystal includes a bisamine two-dimensional perovskite single crystal ABX4 as the light-absorbing layer and an electrode disposed on one side surface of the light-absorbing layer. The electrode is a metal interdigitated electrode, such as a gold interdigitated electrode, or it can be a carbon electrode.

[0043] The method for preparing the X-ray detector includes:

[0044] Step 1) Physically polish the surface of the diamine two-dimensional perovskite single crystal;

[0045] Step 2) Metal interdigitated electrodes are vapor-deposited on the surface of a diamine two-dimensional perovskite single crystal to obtain an X-ray detector for testing.

[0046] In step 1), the mesh size selected for physical polishing is 2000 to 10000.

[0047] This invention relates to a perovskite based on dimethyl biguanide or dicyandiamine, which is a diamine-type two-dimensional structure -ABX4. Two adjacent inorganic layers act as a "trap," and a larger organic ion layer acts as a "barrier." The inorganic layer consists of two octahedrons connected by shared corners. An organic cation is confined within a cage-like space surrounded by four adjacent BX4 octahedrons. Both ends of the dimethyl biguanide or dicyandiamine are connected to the inorganic layer via hydrogen bonds, significantly improving the stiffness of the two-dimensional perovskite lattice, effectively reducing ion migration, and ensuring the stability of the device. Figure 1 As shown.

[0048] Example 1

[0049] Step 1: Weigh DGA and PbO raw materials at a molar ratio of 1:1, dissolve them in HI aqueous solution, add 5% hypophosphoric acid to obtain a mixed precursor solution, stir and heat to 115°C until the solution is transparent, filter to obtain a saturated precursor solution.

[0050] Step 2: Inject the above saturated precursor solution into a crystallizing dish, seal it with 10 layers of polyethylene plastic wrap and high-temperature tape, and place it in a 120°C oven for 2 hours.

[0051] Step 3: Gradually cool to room temperature at a rate of 1℃ / h, filter, and obtain (DGA)PbI4 two-dimensional perovskite single crystal seed crystal; place the seed crystal without obvious defects in a new precursor saturated solution, inject the precursor saturated solution into a crystallizing dish and seal it with 10 layers of polyethylene plastic wrap and high temperature tape, place it in a 120℃ oven and keep it for 2 hours, and then gradually cool to room temperature at a rate of 5℃ / day to obtain centimeter-sized diamine two-dimensional perovskite single crystal - (DGA)PbI4;

[0052] Step 4: Take out the bisamine two-dimensional perovskite single crystal and soak it in anhydrous diethyl ether to clean and remove the impurities remaining on the surface of the bisamine two-dimensional perovskite single crystal during the crystallization process. After cleaning, place it in a vacuum drying oven at 60°C to dry.

[0053] Step 5: Physically polish the cleaned surface of the diamine two-dimensional perovskite single crystal using 7000-grit sandpaper.

[0054] Step 6: After depositing gold interdigitated electrodes on the surface of the diamine two-dimensional perovskite single crystal, place it in a drying bowl for testing.

[0055] Example 2

[0056] Step 1: Weigh DGA and PbO raw materials at a molar ratio of 1:1, dissolve them in HBr aqueous solution, add 10% hypophosphoric acid to obtain a mixed precursor solution, stir and heat to 100°C until the solution is transparent, filter to obtain a saturated precursor solution.

[0057] Step 2: Inject the above saturated precursor solution into a crystallizing dish, seal it with 10 layers of polyethylene plastic wrap and high-temperature tape, and place it in an oven at 115°C for 2 hours.

[0058] Step 3: Gradually cool to room temperature at a rate of 1℃ / h, filter, and obtain (DGA)PbBr4 two-dimensional perovskite single crystal seed crystal; place the seed crystal without obvious defects in a new precursor saturated solution, inject the precursor saturated solution into a crystallizing dish, seal it with 10 layers of polyethylene plastic wrap and high temperature tape, place it in an oven at 115℃ for 2h, and then gradually cool to room temperature at a rate of 4℃ / day to obtain centimeter-sized diamine two-dimensional perovskite single crystal - (DGA)PbBr4;

[0059] Step 4: Take out the bisamine two-dimensional perovskite single crystal and soak it in anhydrous diethyl ether to clean and remove the impurities remaining on the surface of the bisamine two-dimensional perovskite single crystal during the crystallization process. After cleaning, place it in a vacuum drying oven at 60°C to dry.

[0060] Step 5: Physically polish the cleaned surface of the diamine two-dimensional perovskite single crystal using 7000-grit sandpaper.

[0061] Step 6: After depositing gold interdigitated electrodes on the surface of the diamine two-dimensional perovskite single crystal, place it in a drying bowl for testing.

[0062] Example 3

[0063] Step 1: Weigh DGA and PbO raw materials at a molar ratio of 1:1, dissolve them in HCl aqueous solution, add 8% hypophosphoric acid to obtain a mixed precursor solution, stir and heat to 90°C until the solution is transparent, filter to obtain a saturated precursor solution.

[0064] Step 2: Inject the above saturated precursor solution into a crystallizing dish, seal it with 20 layers of polyethylene plastic wrap and high-temperature tape, and place it in a 95°C oven for 2 hours.

[0065] Step 3: Gradually cool to room temperature at a rate of 1℃ / h, filter, and obtain (DGA)PbCl4 two-dimensional perovskite single crystal seed crystal; place the seed crystal without obvious defects in a new precursor saturated solution, inject the precursor saturated solution into a crystallizing dish, seal it with 20 layers of polyethylene plastic wrap and high temperature tape, place it in a 95℃ oven, keep it for 2h, and then gradually cool to room temperature at a rate of 2℃ / day to obtain centimeter-sized diamine two-dimensional perovskite single crystal - (DGA)PbCl4;

[0066] Step 4: Take out the bisamine two-dimensional perovskite single crystal and soak it in anhydrous diethyl ether to clean and remove the impurities remaining on the surface of the bisamine two-dimensional perovskite single crystal during the crystallization process. After cleaning, place it in a vacuum drying oven at 60°C to dry.

[0067] Step 5: Physically polish the cleaned surface of the diamine two-dimensional perovskite single crystal using 10,000-grit sandpaper.

[0068] Step 6: After depositing gold interdigitated electrodes on the surface of the diamine two-dimensional perovskite single crystal, place it in a drying bowl for testing.

[0069] Example 4

[0070] Step 1: Weigh DGA and PbO raw materials at a molar ratio of 1:1, dissolve them in HI aqueous solution, add 10% hypophosphoric acid to obtain a mixed precursor solution, stir and heat to 95°C until the solution is transparent, filter to obtain a saturated precursor solution.

[0071] Step 2: Inject the above saturated precursor solution into a crystallizing dish, seal it with 15 layers of polyethylene plastic wrap and high-temperature tape, and place it in a 100°C oven for 2 hours.

[0072] Step 3: Gradually cool to room temperature at a rate of 1℃ / h, filter, and obtain (DGA)PbI4 two-dimensional perovskite single crystal seed crystal; place the seed crystal without obvious defects in a new precursor saturated solution, inject the precursor saturated solution into a crystallizing dish, seal it with 15 layers of polyethylene plastic wrap and high-temperature tape, place it in a 100℃ oven, keep it for 2h, and then gradually cool to room temperature at a rate of 4℃ / day to obtain centimeter-sized diamine two-dimensional perovskite single crystal - (DGA)PbI4;

[0073] Step 4: Take out the diamine two-dimensional perovskite single crystal and soak it in isopropanol to clean and remove the impurities remaining on the surface of the diamine two-dimensional perovskite single crystal during the crystallization process. After cleaning, place it in a vacuum drying oven at 60°C to dry.

[0074] Step 5: Physically polish the cleaned surface of the diamine two-dimensional perovskite single crystal using 10,000-grit sandpaper.

[0075] Step 6: After depositing gold interdigitated electrodes on the surface of the diamine two-dimensional perovskite single crystal, place it in a drying bowl for testing.

[0076] Example 5

[0077] Step 1: Weigh DGA and PbO raw materials at a molar ratio of 1:1, dissolve them in HBr aqueous solution, add 15% hypophosphoric acid to obtain a mixed precursor solution, stir and heat to 115°C until the solution is transparent, filter to obtain a saturated precursor solution.

[0078] Step 2: Inject the above saturated precursor solution into a crystallizing dish, seal it with 20 layers of polyethylene plastic wrap and high-temperature tape, and place it in a 120°C oven for 2 hours.

[0079] Step 3: Gradually cool to room temperature at a rate of 1℃ / h, filter, and obtain (DGA)PbBr4 two-dimensional perovskite single crystal seed crystal; place the seed crystal without obvious defects in a new precursor saturated solution, inject the precursor saturated solution into a crystallizing dish, seal it with 20 layers of polyethylene plastic wrap and high temperature tape, place it in a 120℃ oven, keep it for 2h, and then gradually cool to room temperature at a rate of 2℃ / day to obtain centimeter-sized diamine two-dimensional perovskite single crystal - (DGA)PbBr4;

[0080] Step 4: Take out the bisamine two-dimensional perovskite single crystal and soak it in acetonitrile to clean and remove the impurities remaining on the surface of the bisamine two-dimensional perovskite single crystal during the crystallization process. After cleaning, place it in a vacuum drying oven at 60°C to dry.

[0081] Step 5: Physically polish the cleaned surface of the diamine two-dimensional perovskite single crystal using 3000-grit sandpaper.

[0082] Step 7: After depositing gold interdigitated electrodes on the surface of the diamine two-dimensional perovskite single crystal, place it in a drying bowl for testing.

[0083] Example 6

[0084] Step 1: Weigh DGA and PbO raw materials at a molar ratio of 1:1, dissolve them in HCl aqueous solution, add 15% hypophosphoric acid to obtain a mixed precursor solution, stir and heat to 100°C until the solution is transparent, filter to obtain a saturated precursor solution.

[0085] Step 2: Inject the above saturated precursor solution into a crystallizing dish, seal it with 16 layers of polyethylene plastic wrap and high-temperature tape, and place it in a 105°C oven for 2 hours.

[0086] Step 3: Gradually cool to room temperature at a rate of 1℃ / h, filter, and obtain (DGA)PbCl4 two-dimensional perovskite single crystal seed crystal; place the seed crystal without obvious defects in a new precursor saturated solution, inject the precursor saturated solution into a crystallizing dish, seal it with 16 layers of polyethylene plastic wrap and high temperature tape, place it in a 105℃ oven, keep it for 2h, and then gradually cool to room temperature at a rate of 5℃ / day to obtain a two-dimensional perovskite single crystal of centimeter size - (DGA)PbCl4;

[0087] Step 4: Take out the bisamine two-dimensional perovskite single crystal and soak it in methanol to clean and remove the impurities remaining on the surface of the bisamine two-dimensional perovskite single crystal during the crystallization process. After cleaning, place it in a vacuum drying oven at 60°C to dry.

[0088] Step 5: Physically polish the cleaned surface of the diamine two-dimensional perovskite single crystal using 7000-grit sandpaper.

[0089] Step 6: After depositing gold interdigitated electrodes on the surface of the diamine two-dimensional perovskite single crystal, place it in a drying bowl for testing.

[0090] Example 7

[0091] Step 1: Weigh DGA and PbO raw materials at a molar ratio of 1:1, dissolve them in HI aqueous solution, add 5% hypophosphoric acid to obtain a mixed precursor solution, stir and heat to 100°C until the solution is transparent, filter to obtain a saturated precursor solution.

[0092] Step 2: Inject the above saturated precursor solution into a crystallizing dish, seal it with 12 layers of polyethylene plastic wrap and high-temperature tape, and place it in a 105°C oven for 2 hours.

[0093] Step 3: Gradually cool to room temperature at a rate of 1℃ / h, filter, and obtain (DGA)PbI4 two-dimensional perovskite single crystal seed crystal; place the seed crystal without obvious defects in a new precursor saturated solution, inject the precursor saturated solution into a crystallizing dish, seal it with 12 layers of polyethylene plastic wrap and high temperature tape, place it in a 105℃ oven, keep it for 2 hours, and then gradually cool to room temperature at a rate of 1℃ / day to obtain centimeter-sized diamine two-dimensional perovskite single crystal - (DGA)PbI4;

[0094] Step 4: Take out the bisamine two-dimensional perovskite single crystal and soak it in toluene to clean and remove the impurities remaining on the surface of the bisamine two-dimensional perovskite single crystal during the crystallization process. After cleaning, place it in a vacuum drying oven at 60°C to dry.

[0095] Step 5: Physically polish the cleaned surface of the diamine two-dimensional perovskite single crystal using 3000-grit sandpaper.

[0096] Step 6: After depositing gold interdigitated electrodes on the surface of the diamine two-dimensional perovskite single crystal, place it in a drying bowl for testing.

[0097] Example 8

[0098] Step 1: Weigh DGA and PbO raw materials at a molar ratio of 1:1, dissolve them in HBr aqueous solution, add 5% hypophosphoric acid to obtain a mixed precursor solution, stir and heat to 90°C until the solution is transparent, filter to obtain a saturated precursor solution.

[0099] Step 2: Inject the above saturated precursor solution into a crystallizing dish, seal it with 11 layers of polyethylene plastic wrap and high-temperature tape, and place it in a 95°C oven for 2 hours.

[0100] Step 3: Gradually cool to room temperature at a rate of 1℃ / h, filter, and obtain (DGA)PbBr4 two-dimensional perovskite single crystal seed crystal; place the seed crystal without obvious defects in a new precursor saturated solution, inject the precursor saturated solution into a crystallizing dish, seal it with 11 layers of polyethylene plastic wrap and high-temperature tape, place it in a 95℃ oven, keep it for 2 hours, and then gradually cool to room temperature at a rate of 1℃ / day to obtain centimeter-sized diamine two-dimensional perovskite single crystal - (DGA)PbBr4;

[0101] Step 4: Take out the bisamine two-dimensional perovskite single crystal and soak it in methanol to clean and remove the impurities remaining on the surface of the bisamine two-dimensional perovskite single crystal during the crystallization process. After cleaning, place it in a vacuum drying oven at 60°C to dry.

[0102] Step 5: Physically polish the cleaned surface of the diamine two-dimensional perovskite single crystal using 10,000-grit sandpaper.

[0103] Step 6: After depositing gold interdigitated electrodes on the surface of the diamine two-dimensional perovskite single crystal, place it in a drying bowl for testing.

[0104] Example 9

[0105] Step 1: Weigh DGA and PbO raw materials at a molar ratio of 1:1, dissolve them in HCl aqueous solution, add 5% hypophosphoric acid to obtain a mixed precursor solution, stir and heat to 115°C until the solution is transparent, filter to obtain a saturated precursor solution.

[0106] Step 2: Inject the above saturated precursor solution into a crystallizing dish, seal it with 18 layers of polyethylene plastic wrap and high-temperature tape, and place it in a 120°C oven for 2 hours.

[0107] Step 3: Gradually cool to room temperature at a rate of 1℃ / h, filter, and obtain (DGA)PbCl4 two-dimensional perovskite single crystal seed crystal; place the seed crystal without obvious defects in a new precursor saturated solution, inject the precursor saturated solution into a crystallizing dish, seal it with 18 layers of polyethylene plastic wrap and high temperature tape, place it in a 120℃ oven, keep it for 2h, and then gradually cool to room temperature at a rate of 1℃ / day to obtain centimeter-sized diamine two-dimensional perovskite single crystal - (DGA)PbCl4;

[0108] Step 4: Take out the diamine two-dimensional perovskite single crystal and soak it in chloroform to clean and remove the impurities remaining on the surface of the diamine two-dimensional perovskite single crystal during the crystallization process. After cleaning, place it in a vacuum drying oven at 60°C to dry.

[0109] Step 5: Physically polish the cleaned surface of the diamine two-dimensional perovskite single crystal using 2000-grit sandpaper.

[0110] Step 6: After depositing gold interdigitated electrodes on the surface of the diamine two-dimensional perovskite single crystal, place it in a drying bowl for testing.

[0111] Example 10

[0112] Step 1: Weigh DGA and PbO raw materials at a molar ratio of 1:1, dissolve them in HI aqueous solution, add 12% hypophosphoric acid to obtain a mixed precursor solution, stir and heat to 105°C until the solution is transparent, filter to obtain a saturated precursor solution.

[0113] Step 2: Inject the above saturated precursor solution into a crystallizing dish, seal it with 12 layers of polyethylene plastic wrap and high-temperature tape, and place it in a 110°C oven for 2 hours.

[0114] Step 3: Gradually cool to room temperature at a rate of 1℃ / h, filter, and obtain (DGA)PbI4 two-dimensional perovskite single crystal seed crystal; place the seed crystal without obvious defects in a new precursor saturated solution, inject the precursor saturated solution into a crystallizing dish, seal it with 12 layers of polyethylene plastic wrap and high temperature tape, place it in a 110℃ oven, keep it for 2h, and then gradually cool to room temperature at a rate of 3℃ / day to obtain centimeter-sized diamine two-dimensional perovskite single crystal - (DGA)PbI4;

[0115] Step 4: Take out the diamine two-dimensional perovskite single crystal and soak it in chloroform to clean and remove the impurities remaining on the surface of the diamine two-dimensional perovskite single crystal during the crystallization process. After cleaning, place it in a vacuum drying oven at 60°C to dry.

[0116] Step 5: Physically polish the cleaned surface of the diamine two-dimensional perovskite single crystal using 3000-grit sandpaper.

[0117] Step 6: After depositing gold interdigitated electrodes on the surface of the diamine two-dimensional perovskite single crystal, place it in a drying bowl for testing.

[0118] Example 11

[0119] Step 1: Weigh DGA and PbO raw materials at a molar ratio of 1:1, dissolve them in HBr aqueous solution, add 11% hypophosphoric acid to obtain a mixed precursor solution, stir and heat to 110°C until the solution is transparent, filter to obtain a saturated precursor solution.

[0120] Step 2: Inject the above saturated precursor solution into a crystallizing dish, seal it with 15 layers of polyethylene plastic wrap and high-temperature tape, and place it in an oven at 115°C for 2 hours.

[0121] Step 3: Gradually cool to room temperature at a rate of 1℃ / h, filter, and obtain (DGA)PbBr4 two-dimensional perovskite single crystal seed crystal; place the seed crystal without obvious defects in a new precursor saturated solution, inject the precursor saturated solution into a crystallizing dish, seal it with 15 layers of polyethylene plastic wrap and high temperature tape, place it in an oven at 115℃ for 2 hours, and then gradually cool to room temperature at a rate of 3℃ / day to obtain centimeter-sized diamine two-dimensional perovskite single crystal - (DGA)PbBr4;

[0122] Step 4: Take out the diamine two-dimensional perovskite single crystal and soak it in isopropanol to clean and remove the impurities remaining on the surface of the diamine two-dimensional perovskite single crystal during the crystallization process. After cleaning, place it in a vacuum drying oven at 60°C to dry.

[0123] Step 5: Physically polish the cleaned surface of the diamine two-dimensional perovskite single crystal using 10,000-grit sandpaper.

[0124] Step 6: After depositing gold interdigitated electrodes on the surface of the diamine two-dimensional perovskite single crystal, place it in a drying bowl for testing.

[0125] Example 12

[0126] Step 1: Weigh DGA and PbO raw materials at a molar ratio of 1:1, dissolve them in HCl aqueous solution, add 9% hypophosphoric acid to obtain a mixed precursor solution, stir and heat to 110°C until the solution is transparent, filter to obtain a saturated precursor solution.

[0127] Step 2: Inject the above saturated precursor solution into a crystallizing dish, seal it with 18 layers of polyethylene plastic wrap and high-temperature tape, and place it in an oven at 115°C for 2 hours.

[0128] Step 3: Gradually cool to room temperature at a rate of 1℃ / h, filter, and obtain (DGA)PbCl4 two-dimensional perovskite single crystal seed crystal; place the seed crystal without obvious defects in a new precursor saturated solution, inject the precursor saturated solution into a crystallizing dish, seal it with 18 layers of polyethylene plastic wrap and high temperature tape, place it in an oven at 115℃ for 2 hours, and then gradually cool to room temperature at a rate of 4℃ / day to obtain centimeter-sized diamine two-dimensional perovskite single crystal - (DGA)PbCl4;

[0129] Step 4: Take out the bisamine two-dimensional perovskite single crystal and soak it in toluene to clean and remove the impurities remaining on the surface of the bisamine two-dimensional perovskite single crystal during the crystallization process. After cleaning, place it in a vacuum drying oven at 60°C to dry.

[0130] Step 5: Physically polish the cleaned surface of the diamine two-dimensional perovskite single crystal using 10,000-grit sandpaper.

[0131] Step 6: After depositing gold interdigitated electrodes on the surface of the diamine two-dimensional perovskite single crystal, place it in a drying bowl for testing.

[0132] Figure 2 The image shows the X-ray diffraction pattern of the diamine two-dimensional perovskite single crystal prepared in Example 1. As can be seen from the image, the diamine two-dimensional perovskite single crystal has obvious crystal orientation and strong diffraction peaks, which further demonstrates that a high-quality two-dimensional perovskite single crystal was synthesized.

[0133] Figure 3 The image shows the steady-state absorption spectrum of the diamine two-dimensional perovskite single crystal prepared in Example 1. The inset shows the optical band gap calculated using the Tauc-Plot method. It can be seen from the figure that (DGA)PbI4 has a suitable band gap, which is beneficial for shielding noise current.

[0134] Figure 4 It is a function of the absorption coefficient of different materials as a function of photon energy, ranging from 10 keV to 1 MeV. Figure 5 This describes the relationship between the attenuation efficiency of different materials for 40 keV energy rays and their thickness. It can be seen that the (DGA)PbI4 perovskite single crystal prepared in Example 1 of this invention, as an absorption layer, has a larger photon absorption coefficient compared to other Si, α-Se, and (oF-PEA)2PbI4 materials. Figure 4 That is, at the same thickness, the attenuation efficiency of rays is higher. Figure 5 Compared to currently commercially available X-ray detectors, the X-ray detector based on perovskite materials in this invention has a larger average relative atomic number because it contains heavy atoms such as Pb and I, which is beneficial for X-ray attenuation.

[0135] Figure 6 The diamine two-dimensional perovskite single-crystal X-ray detector prepared in Example 1 was used at 967.5 μGy air s -1 The It curve under dose, i.e., the It curve under 40keV X-ray irradiation with a bias voltage of 10V, shows that when the X-ray switch is cycled, it has a high switching current ratio, indicating that the device has good detection performance.

[0136] The planar X-ray detector fabricated in this invention has advantages over traditional top-and-bottom structures, including simpler fabrication processes, lower costs, and easier integration. Most importantly, the planar X-ray detector fabricated with interdigitated electrodes achieves a detection limit of 0.0954 μGy. air -1 s -1 This is far below the dose currently required by medicine (5.5 μGy). air -1 s -1 This helps reduce radiation damage to patients during medical use.

Claims

1. A method for preparing a diamine two-dimensional perovskite single crystal, characterized in that, The diamine two-dimensional perovskite single crystal is designated ABX4, where A represents dimethyl biguanide and B represents Pb. 2+ X is Cl - ,Br - Or I - The preparation method includes the following steps: Step 1: Take dimethyl biguanide and BO, dissolve them in an acidic aqueous solution, add hypophosphoric acid to obtain a mixed precursor solution, stir and heat to 90-115°C until the solution is clear, filter to obtain a saturated precursor solution; wherein, the BO is PbO. Step 2: Seal the saturated precursor solution and keep it at 95-120℃ for 2-3 hours to obtain the crystallized solution; Step 3: Cool the crystallized solution to room temperature at a rate of 0.5–2 °C / h, filter, and obtain a two-dimensional perovskite single crystal seed crystal; place the defect-free two-dimensional perovskite single crystal seed crystal in a precursor saturated solution, seal the precursor saturated solution and keep it at 95–120 °C for 2–3 h, and then cool it to room temperature at a rate of 1–5 °C / day to obtain a centimeter-sized diamine two-dimensional perovskite single crystal; Step 4: Clean and dry the centimeter-sized diamine two-dimensional perovskite single crystal to obtain the diamine two-dimensional perovskite single crystal.

2. The method for preparing a diamine two-dimensional perovskite single crystal according to claim 1, characterized in that, In step 1, the molar ratio of dimethyl biguanide to BO is 1:

1.

3. The method for preparing a diamine two-dimensional perovskite single crystal according to claim 1, characterized in that, In step 1, the acidic aqueous solution solvent is at least one of HI acid, HBr acid, and HCl acid.

4. The method for preparing a diamine two-dimensional perovskite single crystal according to claim 1, characterized in that, In step 2, the sealing material is 5 to 20 layers of polyethylene, polyvinyl chloride, or polyvinylidene chloride plastic wrap and high-temperature tape.

5. The method for preparing a diamine two-dimensional perovskite single crystal according to claim 1, characterized in that, In step 4, the organic reagent used for cleaning is anhydrous diethyl ether, isopropanol, acetonitrile, methanol, or chloroform.

6. A two-dimensional perovskite single crystal with diamine obtained by the preparation method according to any one of claims 1 to 5.

7. An X-ray detector, characterized in that, It includes a light-absorbing layer and an electrode disposed on one side surface of the light-absorbing layer; the light-absorbing layer is the diamine two-dimensional perovskite single crystal as described in claim 6.

8. The X-ray detector according to claim 7, characterized in that, The electrode is a metal interdigitated electrode or a carbon electrode.

9. The method for preparing the X-ray detector according to claim 7 or 8, characterized in that, include: Step 1), the surface of the diamine two-dimensional perovskite single crystal is physically polished; Step 2) An electrode is prepared on the physically polished surface of a two-dimensional perovskite single crystal with a diamine.

10. The method for preparing an X-ray detector according to claim 9, characterized in that, In step 1), the mesh size selected for physical polishing is 2000 to 10000.

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