CN117651465A - Multi-step tabletting perovskite heterogeneous crystallization circle X-ray detector and preparation method thereof - Google Patents
Multi-step tabletting perovskite heterogeneous crystallization circle X-ray detector and preparation method thereof Download PDFInfo
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Abstract
The invention relates to a multi-step tabletting perovskite heterogeneous crystallization round X-ray detector and a preparation method thereof, comprising the following steps: s1: preparing at least 2 layers of perovskite wafers which are sequentially stacked by a powder tabletting method, wherein the perovskite wafers of two adjacent layers form a heterojunction; s2: performing heat treatment on at least 2 layers of perovskite wafers to obtain perovskite heterojunction wafers; s3: cathode and anode electrodes are prepared on opposite surfaces of the perovskite heterojunction wafer, respectively. The perovskite wafer is prepared by a powder tabletting method to be used as an active layer of an X-ray detector, so that a thicker perovskite wafer can be realized, the requirement of the X-ray detector on the thickness of an absorption layer can be met, and the X-ray photon absorption efficiency of the detector is improved; meanwhile, the perovskite wafers of two adjacent layers can form a heterojunction, so that ion drift can be restrained, dark current is reduced, and the signal-to-noise ratio and sensitivity of the perovskite X-ray detector are improved, and the performance of the perovskite X-ray detector is improved.
Description
Technical Field
The invention belongs to the technical field of perovskite X-ray detectors, and particularly relates to a multi-step tabletting perovskite heterogeneous crystallization round X-ray detector and a preparation method thereof.
Background
The X-ray has strong penetrating power, so that the X-ray is widely applied to nondestructive detection in various fields such as industrial detection, security inspection, medical inspection, scientific research and the like. Perovskite has great potential in the field of X-ray detection as an emerging electro-optical material due to its many inherent advantages. The chemical composition of perovskite includes many multiple atoms such as cesium, lead, bromine, iodine, etc., which enables it to have a strong X-ray absorbing capacity; perovskite has a generally narrow band gap and high sensitivity to high energy radiation; the perovskite has high carrier mobility and good charge transmission capacity.
In order to sufficiently absorb the incident X-ray photons, the X-ray detector requires a relatively thick active layer. However, obtaining thick perovskite films based on conventional solution techniques is challenging due to the limited solubility and viscosity of perovskite precursors. Sensitivity is a key performance indicator of X-ray detectors, which represents the ability to convert X-rays into electrical signals, and is critical for achieving high contrast images and identification. The ion migration in the perovskite X-ray photon absorption layer can cause the increase and drift of dark current, and then the key parameters such as the minimum detection limit, sensitivity, signal-to-noise ratio and the like of the perovskite X-ray detector are deteriorated. Furthermore, in order to sufficiently absorb the incident X-ray photons, the X-ray detector requires a relatively thick active layer. However, obtaining thick perovskite films based on conventional solution techniques is challenging due to the limited solubility and viscosity of perovskite precursors.
Therefore, how to realize a thicker perovskite X-ray detector active layer, and at the same time, inhibit ion migration and reduce dark current to improve the performance of the perovskite X-ray detector is a current urgent problem to be solved.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a multi-step tabletting perovskite heterogeneous crystallization round X-ray detector and a preparation method thereof. The technical problems to be solved by the invention are realized by the following technical scheme:
the first aspect of the invention provides a preparation method of a multi-step tabletting perovskite heterogeneous crystallization round X-ray detector, which comprises the following steps:
s1: preparing at least 2 layers of perovskite wafers which are sequentially stacked by a powder tabletting method, wherein heterojunction is formed by the perovskite wafers of two adjacent layers;
s2: performing heat treatment on the at least 2 layers of perovskite wafers to obtain perovskite heterojunction wafers;
s3: cathode and anode electrodes are prepared on opposite surfaces of the perovskite heterojunction wafer, respectively.
In a specific embodiment, step S1 includes:
s101: placing the first perovskite precursor powder and the second perovskite precursor powder in a container, and carrying out mixed grinding to obtain mixed perovskite precursor powder;
S102: air-drying the mixed perovskite precursor powder to obtain dried perovskite precursor powder;
s103: placing the dried perovskite precursor powder into a tabletting mold with the diameter of 1-15 cm, wherein the powder filling thickness is 1-50 mm, and pressing for 1-120 min under the pressure of 1-300 mpa to obtain a first perovskite wafer after the pressing is completed;
s104: and changing the material of at least one perovskite precursor powder in the first perovskite precursor powder and the second perovskite precursor powder, and repeating the steps S101-S103 to obtain a second perovskite wafer positioned on the first perovskite wafer.
In a specific embodiment, step S101 includes:
2-10 mol of first perovskite precursor powder and 2-10 mol of second perovskite precursor powder are placed in a container, grinding is repeated for 3-5 times, each grinding time is 30-60 min, and mixed perovskite precursor powder is obtained after grinding is finished; the molar ratio of the first perovskite precursor powder to the second perovskite precursor powder is 1:1, a step of;
step S102 includes:
and placing the mixed perovskite precursor powder in an air drying box at 40-60 ℃, and air-drying for 24-36 h to obtain dried perovskite precursor powder after air-drying is finished.
In a specific embodiment, step S104 further includes:
s105: repeating the step S104 for a plurality of times to obtain a plurality of perovskite wafers positioned on the second perovskite wafer.
In a specific embodiment, the material of the first perovskite precursor powder comprises one or more of FACl, FABr, FAI, MACl, MABr, MAI, csCl, csBr, csI;
the material of the second perovskite precursor powder comprises PbCl 2 、PbBr 2 、PbI 2 One or more of the following.
In a specific embodiment, step S1 further includes:
preparing a carrier transport layer between at least one adjacent two layers of the perovskite wafer;
wherein the material of the carrier transport layer comprises CuAlSe 2 One of ZnTe, carbon nano tube and Mxene, and the thickness is 10-5000 nm.
In a specific embodiment, step S2 includes:
and placing the at least 2 layers of perovskite wafers in a muffle furnace, annealing for 1-10 hours at the temperature of 50-500 ℃ in an air atmosphere, and cooling to room temperature after the annealing is finished to obtain the perovskite heterojunction wafers.
In a specific embodiment, step S3 includes:
respectively preparing a cathode electrode and an anode electrode on two opposite surfaces of the perovskite heterojunction wafer through one or more of an electron beam evaporation process and a magnetron sputtering process;
The cathode electrode is made of one or more of gold, silver, platinum, titanium, aluminum, copper, ITO and IZO, and has a thickness of 50-500 nm;
the anode electrode is made of one or more of gold, silver, platinum, titanium, aluminum, copper, ITO and IZO, and has a thickness of 50-500 nm.
In a specific embodiment, the perovskite wafer has a diameter of 1-15 cm and a thickness of 0.1-5 mm.
In a second aspect, the invention provides a multi-step pressed perovskite heterogeneous crystal round X-ray detector prepared by the preparation method provided by the first aspect of the invention, comprising a cathode electrode, at least 2 layers of perovskite wafers and an anode electrode, wherein,
the at least 2 layers of perovskite wafers are laminated on the cathode electrode, and the anode electrode is positioned on the at least 2 layers of perovskite wafers;
the perovskite wafers of adjacent two layers form a heterojunction.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the invention, the perovskite wafer is prepared by the powder tabletting method to serve as an active layer of the X-ray detector, the powder tabletting method can realize thicker perovskite wafer, the prepared perovskite wafer can meet the requirement of the X-ray detector on the thickness of an absorption layer, and the X-ray photon absorption efficiency of the detector is improved; meanwhile, the perovskite wafers of two adjacent layers can form a heterojunction, the built-in electric field of the heterojunction can inhibit ion drift, dark current is reduced, and the signal-to-noise ratio and sensitivity of the perovskite X-ray detector are improved, so that the performance of the perovskite X-ray detector is improved.
2. The preparation method provided by the invention can prepare the large-area perovskite wafer with millimeter-scale thickness and compactness, and has the advantages of simple preparation process, low cost and high material utilization rate.
Drawings
FIG. 1 is a schematic flow chart of a method for preparing a multi-step pressed perovskite heterogeneous crystal round X-ray detector according to an embodiment of the invention;
fig. 2a to fig. 2c are schematic views of steps of a method for manufacturing a multi-step pressed perovskite heterogeneous crystal round X-ray detector according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of a multi-step pressed perovskite heterogeneous crystallization round X-ray detector provided by an embodiment of the invention;
FIG. 4 shows a multi-step pressed perovskite heterogeneous crystallization circle X-ray detector and CsPbBr according to an embodiment of the invention 3 Current density versus voltage plot for the detector;
FIG. 5 is a schematic structural diagram of a multi-step pressed perovskite heterogeneous crystallization round X-ray detector provided by an embodiment of the invention;
FIG. 6 is a charge transfer diagram of a multi-step pressed perovskite heterogeneous crystallization round X-ray detector provided by an embodiment of the invention in a dark environment;
FIG. 7 is a charge transfer diagram of a multi-step pressed perovskite heterogeneous crystallization round X-ray detector provided by an embodiment of the invention under an X-ray environment;
Fig. 8 is a schematic structural diagram of a multi-step pressed perovskite heterogeneous crystallization round X-ray detector according to an embodiment of the present invention.
Reference numerals:
101: a first perovskite wafer; 102: a second perovskite wafer; 103: a third perovskite wafer; 104: a fourth perovskite wafer; 2: a cathode electrode; 3: an anode electrode; 4: and a carrier transport layer.
Detailed Description
The present invention will be described in further detail with reference to specific examples, but embodiments of the present invention are not limited thereto.
Example 1
Referring to fig. 1, fig. 1 is a schematic flow chart of a preparation method of a multi-step pressed perovskite heterogeneous crystal circle X-ray detector according to an embodiment of the invention.
The preparation method of the multi-step tabletting perovskite heterogeneous crystallization round X-ray detector provided by the embodiment comprises the following steps:
s1: at least 2 perovskite wafers are sequentially stacked by a powder tabletting method, wherein the perovskite wafers of two adjacent layers form a heterojunction.
Specifically, step S1 includes:
s101: and (3) placing the first perovskite precursor powder and the second perovskite precursor powder in a container, and carrying out mixed grinding to obtain mixed perovskite precursor powder.
Specifically, 2-10 mol of first perovskite precursor powder and 2-10 mol of second perovskite precursor powder are placed in a container, repeated grinding is carried out for 3-5 times, each grinding time is 30-60 min, and mixed perovskite precursor powder is obtained after grinding is finished; the molar ratio of the first perovskite precursor powder to the second perovskite precursor powder is 1:1.
the material of the first perovskite precursor powder includes one or more of FACl, FABr, FAI, MACl, MABr, MAI, csCl, csBr, csI. The material of the second perovskite precursor powder comprises PbCl 2 、PbBr 2 、PbI 2 One or more of the following.
S102: and (3) air-drying the mixed perovskite precursor powder to obtain dried perovskite precursor powder.
Specifically, placing the mixed perovskite precursor powder in an air drying box at 40-60 ℃, and air-drying for 24-36 h to obtain the dried perovskite precursor powder after air-drying is finished.
S103: and (3) placing the dried perovskite precursor powder into a tabletting mold with the diameter of 1-15 cm, wherein the powder filling thickness is 1-50 mm, and pressing for 1-120 min under the pressure of 1-300 mpa, so as to obtain the first perovskite wafer after the pressing is completed. Specifically, the perovskite wafer has a diameter of 1-15 cm and a thickness of 0.1-5 mm.
S104: and changing the material of at least one perovskite precursor powder in the first perovskite precursor powder and the second perovskite precursor powder, and repeating the steps S101-S103 to obtain a second perovskite wafer positioned on the first perovskite wafer.
In one implementation, step S104 further includes:
s105: repeating the step S104 for a plurality of times to obtain a plurality of perovskite wafers positioned on the second perovskite wafer.
S2: and carrying out heat treatment on at least 2 layers of perovskite wafers to obtain perovskite heterojunction wafers.
Specifically, at least 2 layers of perovskite wafers are placed in a muffle furnace, annealed at 50-500 ℃ for 1-10 hours in an air atmosphere, and cooled to room temperature after the annealing is finished, so that perovskite heterojunction wafers are obtained.
S3: cathode and anode electrodes are prepared on opposite surfaces of the perovskite heterojunction wafer, respectively.
Specifically, cathode electrodes and anode electrodes are prepared on opposite surfaces of the perovskite heterojunction wafer through one or more of electron beam evaporation and magnetron sputtering processes.
The cathode electrode is made of one or more of gold, silver, platinum, titanium, aluminum, copper, ITO and IZO, and has a thickness of 50-500 nm. The anode electrode is made of one or more of gold, silver, platinum, titanium, aluminum, copper, ITO and IZO, and has a thickness of 50-500 nm.
In one implementation manner, step S1 of the method for manufacturing an X-ray detector provided in this embodiment further includes: a carrier transport layer is prepared between at least one adjacent two layers of perovskite wafers. The material of the carrier transport layer comprises CuAlSe 2 One of ZnTe, carbon nano tube and Mxene, and the thickness of the carrier transmission layer is 10-5000 nm.
Specifically, the perovskite wafers of two adjacent layers are taken as a whole, one perovskite wafer of two adjacent layers is an integral formed by the perovskite wafers of two adjacent layers, one perovskite wafer of two adjacent layers comprises two perovskite wafers of two adjacent layers, every three perovskite wafers of two adjacent layers can be formed by the perovskite wafers of two adjacent layers in sequence, and a carrier transmission layer is prepared between the perovskite wafers of each two adjacent layers at most. A carrier transport layer is prepared between perovskite wafers of one adjacent two layers, i.e. between perovskite wafers of any two adjacent two layers. A carrier transport layer is prepared between a plurality of adjacent two-layer perovskite wafers, i.e., a plurality of carrier transport layers are prepared between a plurality of adjacent two-layer perovskite wafers. The carrier transmission layer is prepared between the perovskite wafers of two adjacent layers, so that the built-in electric field of the heterojunction formed by the perovskite wafers of two adjacent layers can be enhanced, the electron-hole pair recombination is reduced, the carrier transport efficiency is improved, and the performance of the perovskite X-ray detector is further improved.
According to the preparation method of the multi-step tabletting perovskite heterogeneous crystallization round X-ray detector, provided by the embodiment, the perovskite wafer is prepared by a powder tabletting method to serve as an active layer of the X-ray detector, the powder tabletting method can realize thicker perovskite wafers, the prepared perovskite wafer can meet the requirement of the X-ray detector on the thickness of an absorption layer, and the X-ray photon absorption efficiency of the X-ray detector is improved; meanwhile, the perovskite wafers of two adjacent layers prepared by the powder tabletting method can form a heterojunction, the built-in electric field of the heterojunction can inhibit ion drift, dark current is reduced, and the signal-to-noise ratio and the sensitivity of the perovskite X-ray detector are improved, so that the performance of the perovskite X-ray detector is improved. And a carrier transmission layer is prepared between the perovskite wafers of two adjacent layers, so that the built-in electric field of the heterojunction formed by the perovskite wafers of two adjacent layers can be enhanced, the electron-hole pair recombination is reduced, the carrier transmission efficiency is improved, and the performance of the perovskite X-ray detector is further improved. The preparation method provided by the embodiment can control the diameter and thickness of the perovskite wafer by changing the size of the tabletting mould and the thickness of the perovskite precursor powder filling, can prepare the large-area millimeter-sized compact perovskite wafer, and has the advantages of simple preparation process, low cost and high material utilization rate.
Example two
The embodiment provides a multi-step pressed perovskite heterogeneous crystallization round X-ray detector, which is prepared by the preparation method provided in the first embodiment, and comprises a cathode electrode, at least 2 layers of perovskite wafers and an anode electrode. Wherein at least 2 perovskite wafers are laminated on the cathode electrode, the anode electrode is positioned on the at least 2 perovskite wafers, and adjacent perovskite wafers of two layers form a heterojunction.
In one implementation, the X-ray detector provided in this embodiment further includes at least one carrier transport layer. Specifically, at least one carrier transport layer is located between at least one adjacent two-layer perovskite wafer, and at most one carrier transport layer is disposed between each adjacent two-layer perovskite wafer. The perovskite wafers of the adjacent two layers are taken as a whole, one perovskite wafer of the adjacent two layers is a whole formed by the perovskite wafers of the adjacent two layers, and one perovskite wafer of the adjacent two layers comprises two adjacent perovskite wafers, and every three perovskite wafers which are adjacent in sequence can form two perovskite wafers of the adjacent two layers. If the number of the carrier transport layers is one, one carrier transport layer is positioned between perovskite wafers of any two adjacent layers; if the number of the carrier transmission layers is two, the two carrier transmission layers are positioned between any two adjacent perovskite wafers; if the number of carrier transport layers is plural, the plural carrier transport layers are located between any plural perovskite wafers of adjacent two layers. Taking an X-ray detector comprising 4 perovskite wafers as an example, a carrier transport layer is located between any two adjacent perovskite wafers, i.e. comprising: the carrier transport layer is located between the first perovskite wafer and the second perovskite wafer, the carrier transport layer is located between the second perovskite wafer and the third perovskite wafer, and the carrier transport layer is located between the third perovskite wafer and the fourth perovskite wafer; the two carrier transport layers between any two adjacent perovskite wafers include: the first carrier transport layer is located between the first perovskite wafer and the second carrier transport layer is located between the second perovskite wafer and the third perovskite wafer, the first carrier transport layer is located between the first perovskite wafer and the second carrier transport layer is located between the third perovskite wafer and the fourth perovskite wafer, the first carrier transport layer is located between the second perovskite wafer and the third perovskite wafer and the second carrier transport layer is located between the third perovskite wafer and the fourth perovskite wafer.
According to the multi-step tabletting perovskite heterogeneous crystallization round X-ray detector provided by the embodiment, the perovskite wafer is prepared by a powder tabletting method to serve as an active layer of the X-ray detector, the thicker perovskite wafer can be realized by the powder tabletting method, the perovskite wafer provided by the embodiment can meet the requirement of the X-ray detector on the thickness of an absorption layer, and the X-ray photon absorption efficiency of the X-ray detector is improved. And moreover, the perovskite wafers of two adjacent layers can form a heterojunction, the built-in electric field of the heterojunction can inhibit ion drift, dark current is reduced, and the signal-to-noise ratio and the sensitivity of the perovskite X-ray detector are improved, so that the performance of the perovskite X-ray detector is improved. The carrier transmission layers of the perovskite wafers of two adjacent layers can strengthen the built-in electric field of the heterojunction formed by the perovskite wafers of two adjacent layers, reduce electron-hole pair recombination, improve carrier transport efficiency and further improve the performance of the perovskite X-ray detector.
Example III
Referring to fig. 3, the present embodiment provides a multi-step pressed perovskite heterogeneous crystal round X-ray detector, which includes a cathode electrode 2, a 2-layer perovskite wafer and an anode electrode 3, which are sequentially stacked from bottom to top.
Specifically, the 2-layer perovskite wafer includes a first perovskite wafer 101 and a second perovskite wafer 102 disposed from bottom to top. Wherein the material of the first perovskite wafer 101 is CsPbBr 3 The material of the second perovskite wafer 102 is CsPbCl 3 The contact interface of the first perovskite wafer 101 and the second perovskite wafer 102 forms CsPbBr 3 /CsPbCl 3 And a heterojunction. The first perovskite wafer 101 and the second perovskite wafer 102 form the active layer of the X-ray detector. The materials of the cathode electrode 2 and the anode electrode 3 are gold. The anode electrode 3 is an interdigital electrode, and the number of the interdigital electrodes is 10.
Based on the above device structure, the preparation method of the multi-step tabletting perovskite heterogeneous crystallization round X-ray detector provided by the embodiment comprises the following steps:
s1: 2 perovskite wafers are prepared by a powder tabletting method, wherein the perovskite wafers are sequentially laminated. Specifically, the sequentially stacked 2 perovskite wafers are a first perovskite wafer 101 and a second perovskite wafer 102 sequentially arranged from bottom to top. Step S1 includes steps S101 to S104.
S101: taking 5mol of CsBr as the first perovskite precursor powder and 5mol of PbBr respectively 2 And (3) placing the first perovskite precursor powder and the second perovskite precursor powder into a grinding pot body, lightly grinding by using a pestle in the mortar, ensuring proper angle between the pestle and the mortar in the grinding process so as to be sufficiently ground, mixing and grinding for 50min as 1 grinding process, and repeating 5 grinding processes so as to ensure that the first perovskite precursor powder and the second perovskite precursor powder are sufficiently ground, and obtaining the sufficiently ground mixed perovskite precursor powder after finishing grinding.
S102: and (3) placing the mixed perovskite precursor powder in an air drying box at 40 ℃ for 24 hours, and obtaining the dried perovskite precursor powder after the air drying is finished.
S103: and placing the dried perovskite precursor powder into a round powder tabletting mold with the diameter of 2cm, wherein the powder filling depth is 2mm, and pressing for 20min at the room temperature and the pressure of 150MPa, so as to obtain the first perovskite wafer 101 with the thickness of 0.5-1 mm after the pressing is finished. Referring to fig. 2a, the material of the first perovskite wafer 101 obtained through steps S101 to S103 in the present embodiment is CsPbBr 3 。
S104: changing the material of at least one perovskite precursor powder of the first perovskite precursor powder and the second perovskite precursor powder, and repeating the steps S101-S103 once to obtain a second perovskite wafer 102 positioned on the first perovskite wafer 101. Specifically, referring to fig. 2b, the sequentially stacked 2 perovskite wafers are a first perovskite wafer 101 and a second perovskite wafer 102 sequentially disposed from bottom to top. Step S104 includes steps S1041 to S1043.
S1041: taking 2mol of CsCl as the first perovskite precursor powder and PbCl respectively 2 Placing the first perovskite precursor powder and the second perovskite precursor powder into a grinding pot body, lightly grinding the first perovskite precursor powder and the second perovskite precursor powder by using a pestle in the mortar, ensuring the angle between the pestle and the mortar in the grinding process so as to ensure that the grinding is sufficient, and mixing the grinding time 50min to be 1 grinding process so as to ensure that the first perovskite precursor powder and the second perovskite precursor powder are ground And (5) sufficiently repeating the grinding process for 5 times, and obtaining fully-ground mixed perovskite precursor powder after finishing grinding.
S1042: and (3) placing the mixed perovskite precursor powder in an air drying box at 40 ℃, and air-drying for 24 hours at 40 ℃ to obtain the dried perovskite precursor powder after the air drying is finished.
S1043: uniformly spreading the dried perovskite precursor powder on the first perovskite wafer 101, placing the first perovskite wafer 101 paved with the dried perovskite precursor powder in a round powder tabletting mold with the diameter of 2cm, and pressing the powder at room temperature and 150MPa for 20min to obtain a second perovskite wafer 102 with the thickness of 0.1-0.5 mm, which is positioned on the upper surface of the first perovskite wafer 101. The material of the second perovskite wafer 102 obtained through the steps S1041 to S1043 of the present embodiment is CsPbCl 3 。
Specifically, after the end of step S1043, 2 perovskite wafers are obtained, that is, the first perovskite wafer 101 and the second perovskite wafer 102 are sequentially stacked from bottom to top. The material CsPbBr of the first perovskite wafer 101 of the present embodiment 3 And the material CsPbCl of the second perovskite wafer 102 3 The energy levels are matched due to different forbidden bandwidths of the first perovskite wafer 101 and the second perovskite wafer 102, and CsPbBr can be formed at a contact interface 3 /CsPbCl 3 The built-in electric field of the heterojunction can inhibit ion drift, reduce dark current and improve the signal-to-noise ratio and sensitivity of the X-ray detector.
S2: and carrying out heat treatment on the 2-layer perovskite wafer to obtain a perovskite heterojunction wafer.
Specifically, the perovskite wafer with 2 layers obtained in the step S1043 is placed in a muffle furnace, annealed for 2 hours at the temperature of 200 ℃ in an air atmosphere for heat treatment, and slowly cooled to room temperature after the annealing is finished, so as to obtain the perovskite heterojunction wafer. The heat treatment can repair defects in and on the perovskite wafer, so that perovskite particles are more compact, and the carrier transport efficiency is improved.
S3: cathode electrode 2 and anode electrode 3 are prepared on opposite surfaces of the perovskite heterojunction wafer, respectively.
Specifically, referring to fig. 2c, a metal gold having a thickness of 100nm is deposited as the cathode electrode 2 on the lower surface of the first perovskite wafer 101 by an electron beam evaporation process. The cathode electrode 2 covers the lower surface of the first perovskite wafer 101. And (3) tightly attaching a mask plate to the upper surface of the second perovskite wafer 102, and depositing 100nm metal gold as an anode electrode 3 through an electron beam evaporation process. The anode electrode 3 was an interdigital electrode, the number of interdigital was 10, the width of each interdigital was 300 μm, the length was 5mm, and the interval between every two adjacent interdigital was 50 μm.
The active layers of the X-ray detector prepared by the steps S1-S3 of the embodiment are a first perovskite wafer 101 and a second perovskite wafer 102, the thickness of the active layers is 0.6-1.5 mm, and the effective area of a single X-ray detector is 0.0015cm 2 。
The multi-step pressed perovskite heterogeneous crystallization round X-ray detector provided by the embodiment and the prior art only have a single CsPbBr 3 CsPbBr of layer 3 The detector was tested for dark current and photocurrent in both dark and X-ray environments, and the resulting current density versus voltage plot is shown in fig. 4. It can be seen from FIG. 4 that the dark current ratio CsPbBr of the X-ray detector provided by the present embodiment 3 The detector is an order of magnitude lower, and the heterojunction of the X-ray detector provided by the embodiment successfully inhibits dark current of the device. Under the irradiation of X-rays, the photocurrent of the X-ray detector provided by the embodiment is improved.
According to the preparation method of the multi-step tabletting perovskite heterogeneous crystallization round X-ray detector, provided by the embodiment, the perovskite wafer is prepared by a powder tabletting method to serve as an active layer of the X-ray detector, the powder tabletting method can realize thicker perovskite wafers, the prepared perovskite wafer can meet the requirement of the X-ray detector on the thickness of an absorption layer, and the X-ray photon absorption efficiency of the X-ray detector is improved; meanwhile, the perovskite wafers of two adjacent layers prepared by the powder tabletting method can form a heterojunction, the built-in electric field of the heterojunction can inhibit ion drift, dark current is reduced, and the signal-to-noise ratio and the sensitivity of the perovskite X-ray detector are improved, so that the performance of the perovskite X-ray detector is improved. The preparation method provided by the embodiment can control the diameter and thickness of the perovskite wafer by changing the size of the tabletting mould and the thickness of the perovskite precursor powder filling, can prepare the large-area millimeter-sized compact perovskite wafer, and has the advantages of simple preparation process, low cost and high material utilization rate.
Example IV
Referring to fig. 5, fig. 5 is a schematic structural diagram of a multi-step pressed perovskite heterogeneous crystal circle X-ray detector according to an embodiment of the present invention.
The multi-step tabletting perovskite heterogeneous crystallization circle X-ray detector provided by the embodiment comprises a cathode electrode 2, 4 layers of perovskite wafers and an anode electrode 3, wherein the cathode electrode 2, the 4 layers of perovskite wafers and the anode electrode 3 are sequentially arranged from bottom to top.
Specifically, the 4-layer perovskite wafer includes a first perovskite wafer 101, a second perovskite wafer 102, a third perovskite wafer 103, and a fourth perovskite wafer 104, which are disposed in this order from bottom to top. Wherein the material of the first perovskite wafer 101 is MAPbI 3 The material of the second perovskite wafer 102 is CsPbBr 3 The material of the third perovskite wafer 103 is CsPbBr 3 Cl 3-x The material of the fourth perovskite wafer 104 is CsPbCl 3 . The contact interface of the first perovskite wafer 101 and the second perovskite wafer 102 forms MAPbI 3 /CsPbBr 3 Heterojunction, contact interface of second perovskite wafer 102 and third perovskite wafer 103 forms CsPbBr 3 /CsPbBr 3 Cl 3-x Heterojunction, contact interface of third perovskite wafer 103 and fourth perovskite wafer 104 forms CsPbBr 3 Cl 3-x /CsPbCl 3 And a heterojunction. The first perovskite wafer 101, the second perovskite wafer 102, the third perovskite wafer 103 and the fourth perovskite wafer 104 form an active layer of an X-ray detector. The materials of the cathode electrode 2 and the anode electrode 3 are gold. The anode electrode 3 was an interdigital electrode, the number of interdigital electrodes was 12, the width of each interdigital electrode was 500 μm, the length was 5 mm, and the pitch of two adjacent interdigital electrodes was 50 μm.
Based on the above device structure, the preparation method of the multi-step tabletting perovskite heterogeneous crystallization round X-ray detector provided by the embodiment comprises the following steps:
s1: 4 perovskite wafers which are sequentially laminated are prepared by a powder tabletting method. Specifically, the 4-layer perovskite wafers are a first perovskite wafer 101, a second perovskite wafer 102, a third perovskite wafer 103 and a fourth perovskite wafer 104 which are sequentially arranged from bottom to top. Step S1 includes steps S101 to S105.
S101: taking 5mol of MAI as the first perovskite precursor powder and 5mol of PbI respectively 2 And (3) placing the first perovskite precursor powder and the second perovskite precursor powder into a grinding pot body, lightly grinding by using a pestle in the mortar, ensuring proper angle between the pestle and the mortar in the grinding process so as to be sufficiently ground, mixing and grinding for 50 min for 1 grinding process, and repeating the grinding process for 5 times so as to ensure that the first perovskite precursor powder and the second perovskite precursor powder are sufficiently ground, and obtaining the sufficiently ground mixed perovskite precursor powder after the grinding is finished.
S102: and (3) placing the mixed perovskite precursor powder in an air drying box, and air-drying for 24 hours at the temperature of 40 ℃ to obtain dried perovskite precursor powder.
S103: placing the dried perovskite precursor powder into a round powder tabletting mold with the diameter of 3cm, wherein the powder filling depth is about 2mm, pressing for 20min at the room temperature under the pressure of 350MPa, and obtaining a first perovskite wafer 101 with the thickness of 0.5-1 mm after the pressing is completed, wherein the material of the first perovskite wafer 101 obtained through the steps S101-S103 in the embodiment is MAPbI 3 。
S104: and changing at least one of the first perovskite precursor powder and the second perovskite precursor powder, and repeating the steps S101-S103 for one time to obtain 2 layers of perovskite wafers which are sequentially laminated. Specifically, the sequentially stacked 2 perovskite wafers are a first perovskite wafer 101 and a second perovskite wafer 102 sequentially arranged from bottom to top. Step S104 includes steps S1041 to S1043.
S1041: taking 5mol of CsBr as the first perovskite precursor powder and 5mol of PbBr respectively 2 Is the second perovskite precursor powderAnd finally, placing the first perovskite precursor powder and the second perovskite precursor powder into a grinding pot body, lightly grinding by using a pestle in the mortar, ensuring proper angle between the pestle and the mortar in the grinding process so as to be sufficiently ground, mixing and grinding for 50min to be 1 grinding process, and repeating 5 grinding processes so as to ensure that the first perovskite precursor powder and the second perovskite precursor powder are sufficiently ground, so as to obtain sufficiently ground mixed perovskite precursor powder after finishing grinding.
S1042: and (3) placing the mixed perovskite precursor powder in an air drying box at 40 ℃, and air-drying for 24 hours at 40 ℃ to obtain the dried perovskite precursor powder after the air drying is finished.
S1043: uniformly spreading the dried perovskite precursor powder on the first perovskite wafer 101, placing the first perovskite wafer 101 paved with the dried perovskite precursor powder in a round powder tabletting mold with the diameter of 3cm, and pressing the powder filling depth of about 2mm at room temperature under the pressure of 150MPa for 20min to obtain a second perovskite wafer 102 with the thickness of 0.5-1 mm, which is positioned on the upper surface of the first perovskite wafer 101. The material of the second perovskite wafer 102 obtained through the steps S1041 to S1043 of the present embodiment is CsPbBr 3 。
Specifically, after the end of step S1043, 2 perovskite wafers are obtained, that is, the first perovskite wafer 101 and the second perovskite wafer 102 are sequentially stacked from bottom to top. The material MAPbI of the first perovskite wafer 101 of the present embodiment 3 And material CsPbBr of the second perovskite wafer 102 3 The first perovskite wafer 101 and the second perovskite wafer 102 can form MAPbI at the contact interface 3 /CsPbBr 3 And a heterojunction.
S105: step S104 is repeated twice to obtain two perovskite wafers on the second perovskite wafer 102, i.e., 4 perovskite wafers stacked in order. Specifically, the 4-layer perovskite wafers are a first perovskite wafer 101, a second perovskite wafer 102, a third perovskite wafer 103 and a fourth perovskite wafer 104 which are sequentially arranged from bottom to top. Step S105 includes steps S1051 to S1056.
S1051: taking 1mol of CsBr and 1mol of CsCl as first perovskite precursor powder respectively, and taking 1mol of PbBr respectively 2 And 1mol of PbCl 2 And (3) placing the first perovskite precursor powder and the second perovskite precursor powder into a grinding pot body, lightly grinding by using a pestle in the mortar, ensuring proper angle between the pestle and the mortar in the grinding process so as to be sufficiently ground, mixing the grinding time for 50min to be 1 grinding process, and repeating the grinding process for 5 times so as to ensure that the first perovskite precursor powder and the second perovskite precursor powder are sufficiently ground, and obtaining the sufficiently ground mixed perovskite precursor powder after the grinding is finished.
S1052: and (3) placing the mixed perovskite precursor powder in an air drying box at 40 ℃, and air-drying for 24 hours at 40 ℃ to obtain the dried perovskite precursor powder after the air drying is finished.
S1053: uniformly spreading the dried perovskite precursor powder on the upper surface of the second perovskite wafer 102 of the 2-layer perovskite wafer obtained in the step S1043, placing the 2-layer perovskite wafer paved with the dried perovskite precursor powder in a round powder tabletting mold with the diameter of 3cm, and pressing the powder at room temperature and under the pressure of 200MPa for 20min to obtain a third perovskite wafer 103 with the thickness of 0.1-0.5 mm, which is positioned on the upper surface of the second perovskite wafer 102. The material of the third perovskite wafer 103 obtained through the steps S1051 to S1053 of the present embodiment is CsPbBr 3 Cl 3-x 。
Specifically, after the end of step S1053, 3 perovskite wafers are obtained, which are sequentially stacked, that is, the first perovskite wafer 101, the second perovskite wafer 102, and the third perovskite wafer 103 are sequentially arranged from bottom to top. The material CsPbBr of the second perovskite wafer 102 of the present embodiment 3 And a material CsPbBr of the third perovskite wafer 103 3 Cl 3-x The energy level is matched due to the difference of the forbidden bandwidths of the second perovskite wafer 102 and the third perovskite wafer 103, and CsPbBr can be formed at the contact interface 3 /CsPbBr 3 Cl 3-x And a heterojunction.
S1054: taking 2mol of CsCl as the first perovskite precursor powder and 2mol of CsCl as the second perovskite precursor powderPbCl of l 2 And (3) placing the first perovskite precursor powder and the second perovskite precursor powder into a grinding pot body, lightly grinding by using a pestle in the mortar, ensuring proper angle between the pestle and the mortar in the grinding process so as to be sufficiently ground, mixing the grinding time for 50min to be 1 grinding process, and repeating the grinding process for 5 times so as to ensure that the first perovskite precursor powder and the second perovskite precursor powder are sufficiently ground, and obtaining the sufficiently ground mixed perovskite precursor powder after the grinding is finished.
S1055: and (3) placing the mixed perovskite precursor powder in an air drying box at 40 ℃, and air-drying for 24 hours at 40 ℃ to obtain the dried perovskite precursor powder after the air drying is finished.
S1056: uniformly spreading the dried perovskite precursor powder on the upper surface of the third perovskite wafer 103 of the 3-layer perovskite wafer obtained in the step S1053, placing the 3-layer perovskite wafer paved with the dried perovskite precursor powder in a round powder tabletting mold with the diameter of 3cm, and pressing the powder at room temperature and 150MPa for 20min to obtain a fourth perovskite wafer 104 with the thickness of 0.1-0.5 mm, which is positioned on the upper surface of the second perovskite wafer 102. The material of the third perovskite wafer 103 obtained through the steps S1041 to S1042 of the present embodiment is CsPbCl 3 。
Specifically, after the end of step S1056, 4 perovskite wafers are obtained, which are stacked in order, that is, a first perovskite wafer 101, a second perovskite wafer 102, a third perovskite wafer 103, and a fourth perovskite wafer 104 are sequentially disposed from bottom to top. The material CsPbBr of the third perovskite wafer 103 of the present embodiment 3 Cl 3-x And the material CsPbCl of the fourth perovskite wafer 104 3 The energy level is matched due to the difference of the forbidden bandwidths of the third perovskite wafer 103 and the fourth perovskite wafer 104, and CsPbBr can be formed at the contact interface 3 Cl 3-x /CsPbCl 3 And a heterojunction.
S2: and carrying out heat treatment on the 4-layer perovskite wafer to obtain the perovskite heterojunction wafer.
Specifically, the 4-layer perovskite wafer obtained in the step S1056 is placed in a muffle furnace, annealed for 2 hours at the temperature of 250 ℃ in an air atmosphere for heat treatment, and slowly cooled to room temperature after the annealing is finished, so as to obtain the perovskite heterojunction wafer. The heat treatment can repair defects in and on the perovskite wafer, so that perovskite particles are more compact, and the carrier transport efficiency is improved.
S3: cathode electrode 2 and anode electrode 3 are prepared on opposite surfaces of the perovskite heterojunction wafer, respectively.
Specifically, metallic gold having a thickness of 100nm is deposited as the cathode electrode 2 on the lower surface of the first perovskite wafer 101 by an electron beam evaporation process. The cathode electrode 2 covers the lower surface of the first perovskite wafer 101.
And a mask is tightly attached to the upper surface of the fourth perovskite wafer 104, and 100nm of metal gold is deposited as an anode electrode 3 through an electron beam evaporation process. The anode electrode 3 was an interdigital electrode, the number of interdigital was 12, the width of each interdigital was 500 μm, the length was 5mm, and the interval between every two adjacent interdigital was 50 μm.
The active layers of the X-ray detector prepared by the steps S1-S3 of the embodiment are a first perovskite wafer 101, a second perovskite wafer 102, a third perovskite wafer 103 and a fourth perovskite wafer 104, the thickness of the active layers is 1.2-3 mm, and the effective area of a single X-ray detector is 0.003cm 2 。
Referring to fig. 6 and 7, fig. 6 is a charge transfer diagram of a multi-step pressed perovskite heterogeneous crystalline circle X-ray detector provided by an embodiment of the invention in a dark environment, and fig. 7 is a charge transfer diagram of a multi-step pressed perovskite heterogeneous crystalline circle X-ray detector provided by an embodiment of the invention in an X-ray environment. As can be seen from fig. 6 and 7, MAPbI 3 、CsPbBr 3 、CsPbBr 3 Cl 3-x And CsPbCl 3 Energy level matching, the contact interface of the first perovskite wafer 101 and the second perovskite wafer 102 forms MAPbI 3 /CsPbBr 3 Heterojunction, contact interface of second perovskite wafer 102 and third perovskite wafer 103 forms CsPbBr 3 /CsPbBr 3 Cl 3-x Heterojunction, third perovskite wafer 103 and fourth perovskiteContact interface formation CsPbBr of titanium ore wafer 104 3 Cl 3-x /CsPbCl 3 And a heterojunction. It can be seen from fig. 6 that the heterojunction barrier blocks the transport of electrons, resulting in a reduced dark current in a dark environment. In particular, the conduction band is the energy band in a solid that is located above the valence band. Electrons are free to move in the conduction band, so electrons on the conduction band can participate in the conduction of current. When an applied electric field or other form of excitation acts on the electrons on the conductive strip, they can move and form an electric current. The valence band is another energy band, located below the conduction band. In the valence band, electrons are at a lower energy level, tightly bound to the nucleus. Electrons on the valence band are generally not involved in current conduction because of their low energy in the valence band, which is not easily moved by external excitation. In the dark, the semiconductor material generates carriers (electrons and holes) due to thermal excitation at room temperature, and electrons in the conduction band participate in conduction, so that current is formed by moving to the positive electrode, and current is formed by moving to the negative electrode. Since the energy band distributions of different perovskite wafers are different (the positions of the conduction band and the valence band are different), the introduced heterojunction forms a barrier height, and electrons are difficult to cross the barrier upwards, so that electrons which can reach the anode across the barrier height are reduced, and dark current is reduced. As can be seen from FIG. 7, csPbCl is present in the X-ray environment, i.e. in the case of X-ray irradiation 3 Can absorb X-rays at a short distance, and can absorb CsPbCl 3 The layer generates the majority of photogenerated carriers (electrons and holes), csPbCl 3 Electron-hole pairs generated by absorption of X-ray photons contribute a substantial portion of the photocurrent. In which electrons reach the positive electrode very easily and holes reach the negative electrode upwards very easily, so the potential barrier of the heterojunction has very little effect on the photocurrent.
According to the preparation method of the multi-step tabletting perovskite heterogeneous crystallization round X-ray detector, provided by the embodiment, the perovskite wafer is prepared by the powder tabletting method to serve as an active layer of the X-ray detector, the thicker perovskite wafer can be realized by the powder tabletting method, the requirement of the X-ray detector on the thickness of an absorption layer can be met, and the X-ray photon absorption efficiency of the X-ray detector is improved. According to the perovskite wafer with the adjacent two layers prepared by the powder tabletting method, a heterojunction can be formed at a contact interface, the built-in electric field of the heterojunction can inhibit ion drift, dark current is reduced, and the signal-to-noise ratio and the sensitivity of the perovskite X-ray detector are improved. The preparation method provided by the embodiment can control the diameter and thickness of the perovskite wafer by changing the size of the tabletting mould and the thickness of the perovskite precursor powder filling, can prepare the large-area millimeter-sized compact perovskite wafer, and has the advantages of simple preparation process, low cost and high material utilization rate.
Example five
Referring to fig. 8, fig. 8 is a schematic structural diagram of a multi-step pressed perovskite heterogeneous crystal circle X-ray detector according to an embodiment of the present invention.
The multi-step tabletting perovskite heterogeneous crystallization circle X-ray detector provided by the embodiment comprises a cathode electrode 2, a first perovskite wafer 101, a carrier transmission layer 4, a second perovskite wafer 102 and an anode electrode 3 which are sequentially arranged from bottom to top. Wherein the material of the first perovskite wafer 101 is CsPbBr 3 The material of the second perovskite wafer 102 is CsPbCl 3 The first perovskite wafer 101 and the second perovskite wafer 102 form CsPbBr 3 /CsPbCl 3 And a heterojunction. The first perovskite wafer 101 and the second perovskite wafer 102 form the active layer of the X-ray detector. The materials of the cathode electrode 2 and the anode electrode 3 are gold. The anode electrode 3 is an interdigital electrode, and the number of the interdigital electrodes is 10.
Based on the above device structure, the preparation method of the multi-step tabletting perovskite heterogeneous crystallization round X-ray detector provided by the embodiment comprises the following steps:
s1: 2 perovskite wafers are prepared by a powder tabletting method, and a carrier transport layer 4 positioned between the 2 perovskite wafers is prepared by a radio frequency magnetron sputtering process.
S101: taking 5mol of CsBr as the first perovskite precursor powder and 5mol of PbBr respectively 2 For the second perovskite precursor powder, the first perovskite precursor powder and the second perovskite precursor powder are placed in a grinding pot body, and are lightly ground by using a pestle in the mortar, and the pestle is ensured in the grinding processThe angle between the perovskite precursor powder and the mortar is proper so as to be sufficiently ground, the mixed grinding is carried out for 50min for 1 grinding process, in order to ensure that the first perovskite precursor powder and the second perovskite precursor powder are sufficiently ground, 5 grinding processes are repeated, and the sufficiently ground mixed perovskite precursor powder is obtained after the grinding is finished.
S102: and (3) placing the mixed perovskite precursor powder in an air drying box at 40 ℃ for 24 hours, and obtaining the dried perovskite precursor powder after the air drying is finished.
S103: and placing the dried perovskite precursor powder into a round powder tabletting mold with the diameter of 2cm, wherein the powder filling depth is 2mm, and pressing for 20min at the room temperature and the pressure of 150MPa, so as to obtain the first perovskite wafer 101 with the thickness of 0.5-1 mm after the pressing is finished. The material of the first perovskite wafer 101 obtained through step S101 to step S103 of the present embodiment is CsPbBr 3 。
S104: a carrier transport layer 4 is deposited on the upper surface of the first perovskite wafer 101.
Specifically, znTe having a thickness of 100nm is deposited as the carrier transport layer 4 on the upper surface of the first perovskite wafer 101 by a radio frequency magnetron sputtering process. Wherein, the sputtering power is 30W, the sputtering atmosphere is argon, the sputtering growth pressure is 10mTorr, the sputtering substrate temperature is 100 ℃, the distance between the sputtering target and the sputtering substrate is 8cm, the purity of the used ZnTe target is more than 99%, and the size of the sputtering target is 2 inches.
S105: and (3) changing at least one of the first perovskite precursor powder and the second perovskite precursor powder, and repeating the steps S101-S103 once to obtain a first perovskite wafer 101, a carrier transport layer 4 and a second perovskite wafer 102 which are sequentially arranged from bottom to top. Step S105 includes steps S1051 to S1053.
S1051: taking 2mol of CsCl as the first perovskite precursor powder and PbCl respectively 2 Placing the first perovskite precursor powder and the second perovskite precursor powder into a grinding pot body, lightly grinding by using a pestle in the mortar, ensuring the angle between the pestle and the mortar in the grinding process so as to ensure full grinding, and mixing and grinding for 50min for 1 grinding passAnd (3) repeating the grinding process for 5 times in order to ensure that the first perovskite precursor powder and the second perovskite precursor powder are sufficiently ground, and obtaining fully ground mixed perovskite precursor powder after finishing grinding.
S1052: and (3) placing the mixed perovskite precursor powder in an air drying box at 40 ℃, and air-drying for 24 hours at 40 ℃ to obtain the dried perovskite precursor powder after the air drying is finished.
S1053: uniformly spreading the dried perovskite precursor powder on the first perovskite wafer 101, placing the first perovskite wafer 101 paved with the dried perovskite precursor powder in a round powder tabletting mold with the diameter of 2cm, and pressing the powder at room temperature and 150MPa for 20min to obtain a second perovskite wafer 102 with the thickness of 0.1-0.5 mm, which is positioned on the upper surface of the first perovskite wafer 101. The material of the second perovskite wafer 102 obtained through the steps S1051 to S1053 of the present embodiment is CsPbCl 3 。
Specifically, the first perovskite wafer 101, the carrier transporting layer 4, and the second perovskite wafer 102, which are sequentially disposed from bottom to top, are obtained after the end of step S1053. The material CsPbBr of the first perovskite wafer 101 of the present embodiment 3 And the material CsPbCl of the second perovskite wafer 102 3 Is different in forbidden band width, energy levels are matched, and the first perovskite wafer 101 and the second perovskite wafer 102 can form CsPbBr 3 /CsPbCl 3 The built-in electric field of the heterojunction can inhibit ion drift, reduce dark current and improve the signal-to-noise ratio and sensitivity of the X-ray detector. The carrier transport layer 4 between the first perovskite wafer 101 and the second perovskite wafer 102 may reduce electron-hole pair recombination, increasing carrier transport capability.
S2: and (3) performing heat treatment on the structure obtained in the step (S1) to obtain the perovskite heterojunction wafer.
Specifically, the structure obtained in the step S1053 is placed in a muffle furnace, and is annealed for 2 hours at 200 ℃ in an air atmosphere for heat treatment, and after the annealing is finished, the structure is slowly cooled to room temperature, and tight bonding among the multi-layer structures is realized through the heat treatment, so that the perovskite heterojunction wafer is obtained. The heat treatment can repair defects in and on the perovskite wafer, so that perovskite particles are more compact, and the carrier transport efficiency is improved.
S3: cathode electrode 2 and anode electrode 3 are prepared on opposite surfaces of the perovskite heterojunction wafer, respectively.
Specifically, metallic gold having a thickness of 100nm is deposited as the cathode electrode 2 on the lower surface of the first perovskite wafer 101 by an electron beam evaporation process. The cathode electrode 2 covers the lower surface of the first perovskite wafer 101.
And (3) tightly attaching a mask plate to the upper surface of the second perovskite wafer 102, and depositing 100nm metal gold as an anode electrode 3 through an electron beam evaporation process. The anode electrode 3 was an interdigital electrode, the number of interdigital was 10, the width of each interdigital was 300 μm, the length was 5mm, and the interval between every two adjacent interdigital was 50 μm.
The active layers of the X-ray detector prepared by the steps S1-S3 of the embodiment are a first perovskite wafer 101 and a second perovskite wafer 102, the thickness of the active layers is 0.6-1.5 mm, and the effective area of a single X-ray detector is 0.0015cm 2 。
According to the preparation method of the multi-step tabletting perovskite heterogeneous crystallization round X-ray detector, provided by the embodiment, the perovskite wafer is prepared by the powder tabletting method to serve as an active layer of the X-ray detector, the thicker perovskite wafer can be realized by the powder tabletting method, the requirement of the X-ray detector on the thickness of an absorption layer can be met, and the X-ray photon absorption efficiency of the X-ray detector is improved. Meanwhile, the perovskite wafers of two adjacent layers can form a heterojunction, the built-in electric field of the heterojunction can inhibit ion drift, dark current is reduced, and the signal-to-noise ratio and the sensitivity of the perovskite X-ray detector are improved. And a carrier transmission layer 4 is arranged between the first perovskite wafer 101 and the second perovskite wafer 102, and the carrier transmission layer 4 can enhance the built-in electric field of the heterojunction formed by the first perovskite wafer 101 and the second perovskite wafer 102, reduce electron-hole pair recombination, improve carrier transport efficiency and further improve the performance of the perovskite X-ray detector. The preparation method provided by the embodiment can control the diameter and thickness of the perovskite wafer by changing the size of the tabletting mould and the thickness of the perovskite precursor powder filling, can prepare the large-area millimeter-sized compact perovskite wafer, and has the advantages of simple preparation process, low cost and high material utilization rate.
The foregoing is a further detailed description of the invention in connection with the preferred embodiments, and it is not intended that the invention be limited to the specific embodiments described. It will be apparent to those skilled in the art that several simple deductions or substitutions may be made without departing from the spirit of the invention, and these should be considered to be within the scope of the invention.
Claims (10)
1. The preparation method of the multi-step tabletting perovskite heterogeneous crystallization round X-ray detector is characterized by comprising the following steps of:
s1: preparing at least 2 layers of perovskite wafers which are sequentially stacked by a powder tabletting method, wherein heterojunction is formed by the perovskite wafers of two adjacent layers;
s2: performing heat treatment on the at least 2 layers of perovskite wafers to obtain perovskite heterojunction wafers;
s3: cathode and anode electrodes are prepared on opposite surfaces of the perovskite heterojunction wafer, respectively.
2. The method for manufacturing a multi-step pressed perovskite heterogeneous crystal round X-ray detector according to claim 1, wherein step S1 comprises:
s101: placing the first perovskite precursor powder and the second perovskite precursor powder in a container, and carrying out mixed grinding to obtain mixed perovskite precursor powder;
S102: air-drying the mixed perovskite precursor powder to obtain dried perovskite precursor powder;
s103: placing the dried perovskite precursor powder into a tabletting mold with the diameter of 1-15 cm, wherein the powder filling thickness is 1-50 mm, and pressing for 1-120 min under the pressure of 1-300 mpa to obtain a first perovskite wafer after the pressing is completed;
s104: and changing the material of at least one perovskite precursor powder in the first perovskite precursor powder and the second perovskite precursor powder, and repeating the steps S101-S103 to obtain a second perovskite wafer positioned on the first perovskite wafer.
3. The method for manufacturing a multi-step pressed perovskite heterogeneous crystal round X-ray detector according to claim 2, wherein step S101 comprises:
2-10 mol of first perovskite precursor powder and 2-10 mol of second perovskite precursor powder are placed in a container, grinding is repeated for 3-5 times, each grinding time is 30-60 min, and mixed perovskite precursor powder is obtained after grinding is finished; the molar ratio of the first perovskite precursor powder to the second perovskite precursor powder is 1:1, a step of;
step S102 includes:
and placing the mixed perovskite precursor powder in an air drying box at 40-60 ℃, and air-drying for 24-36 h to obtain dried perovskite precursor powder after air-drying is finished.
4. The method for manufacturing a multi-step pressed perovskite heterogeneous crystal round X-ray detector according to claim 2, further comprising, after step S104:
s105: repeating the step S104 for a plurality of times to obtain a plurality of perovskite wafers positioned on the second perovskite wafer.
5. A method of manufacturing a multi-step tableted perovskite heterogeneous crystalline round X-ray detector according to any one of claims 2 to 4, wherein the material of the first perovskite precursor powder comprises one or more of FACl, FABr, FAI, MACl, MABr, MAI, csCl, csBr, csI;
the material of the second perovskite precursor powder comprises PbCl 2 、PbBr 2 、PbI 2 One or more of the following.
6. The method for manufacturing a multi-step pressed perovskite heterogeneous crystal round X-ray detector according to claim 1, wherein step S1 further comprises:
preparing a carrier transport layer between at least one adjacent two layers of the perovskite wafer;
wherein the material of the carrier transport layer comprises CuAlSe 2 One of ZnTe, carbon nano tube and Mxene, and the thickness is 10-5000 nm.
7. The method for manufacturing a multi-step pressed perovskite heterogeneous crystal round X-ray detector according to claim 1, wherein step S2 comprises:
And placing the at least 2 layers of perovskite wafers in a muffle furnace, annealing for 1-10 hours at the temperature of 50-500 ℃ in an air atmosphere, and cooling to room temperature after the annealing is finished to obtain the perovskite heterojunction wafers.
8. The method for manufacturing a multi-step pressed perovskite heterogeneous crystal round X-ray detector according to claim 1, wherein step S3 comprises:
respectively preparing a cathode electrode and an anode electrode on two opposite surfaces of the perovskite heterojunction wafer through one or more of an electron beam evaporation process and a magnetron sputtering process;
the cathode electrode is made of one or more of gold, silver, platinum, titanium, aluminum, copper, ITO and IZO, and has a thickness of 50-500 nm;
the anode electrode is made of one or more of gold, silver, platinum, titanium, aluminum, copper, ITO and IZO, and has a thickness of 50-500 nm.
9. The method for manufacturing the multi-step tabletting perovskite heterogeneous crystallization round X-ray detector is characterized in that the diameter of the perovskite wafer is 1-15 cm, and the thickness of the perovskite wafer is 0.1-5 mm.
10. A multi-step pressed perovskite heterogeneous crystal round X-ray detector, which is characterized by being prepared by the preparation method according to any one of claims 1 to 9 and comprising a cathode electrode, at least 2 layers of perovskite wafers and an anode electrode, wherein,
The at least 2 layers of perovskite wafers are laminated on the cathode electrode, and the anode electrode is positioned on the at least 2 layers of perovskite wafers;
the perovskite wafers of adjacent two layers form a heterojunction.
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