CN116193943A

CN116193943A - Perovskite radiation detector based on Schottky junction and preparation method thereof

Info

Publication number: CN116193943A
Application number: CN202310228359.3A
Authority: CN
Inventors: 肖正国; 张以涵
Original assignee: University of Science and Technology of China USTC
Current assignee: University of Science and Technology of China USTC
Priority date: 2023-03-10
Filing date: 2023-03-10
Publication date: 2023-05-30

Abstract

The present disclosure proposes a method of fabricating a schottky junction based perovskite radiation detector comprising: the carbon slurry is coated on a first substrate to form a film, and the film is annealed to obtain a carbon electrode layer; spreading the carbon slurry on a second substrate to form a film, soaking the film in an organic solvent for more than 10 minutes, stripping the carbon film from the second substrate, and standing the film in air until the organic solvent is completely volatilized to obtain a porous carbon film; dissolving organic ammonium salt or cesium salt and metal halide in a polar organic solvent to obtain a perovskite solution, pouring the perovskite solution on a porous carbon film, enabling the perovskite solution to permeate into the porous carbon film under the pressure condition, and annealing to obtain a radiation absorption layer composed of a porous carbon-perovskite composite material; laminating the radiation absorbing layer and the carbon electrode layer; and sequentially preparing a perovskite layer, a hole injection layer and a top electrode layer on the radiation absorption layer to obtain the perovskite radiation detector based on the Schottky junction.

Description

Perovskite radiation detector based on Schottky junction and preparation method thereof

Technical Field

The disclosure belongs to the field of radiation detection, and in particular relates to a perovskite radiation detector based on a Schottky structure and a preparation method thereof.

Background

A radiation detector (radiation detector) is a sensing device that observes and studies microscopic phenomena of nuclear radiation and particles, the working principle of which is based on the interaction of particles with a substance. An X-ray detector (X-ray detector) is used as one of the radiation detectors, and can convert X-rays into a digital signal which can be finally converted into an image, so that the X-ray detector is widely applied to the fields of medical diagnosis, radiation therapy, deep space detection, geological exploration, industrial nondestructive inspection, environmental radiation monitoring and the like.

In recent years, the development of perovskite radiation detectors has been very rapid, and the performance of perovskite single crystal semiconductor radiation detectors grown based on solution methods has far exceeded that of conventional semiconductor radiation detectors such as amorphous selenium, mercury iodide, and the like. At present, a perovskite radiation detector adopts a traditional layered structure, wherein photo-generated carriers need to migrate the thickness length of a device to obtain higher detection sensitivity, and an operating voltage of tens to hundreds of volts is usually required to be applied to the device, and the larger operating voltage can aggravate ion movement, reduce the stability of the device and limit the application of the perovskite semiconductor radiation detector in portable radiation detection equipment.

In addition, there are other issues that need to be addressed in the development of perovskite semiconductor radiation detectors, such as: the perovskite single crystal material prepared by the solution growth method has the advantages that the size of the radiation absorbing layer is limited, the preparation of a large-area and high-quality perovskite X-ray absorbing layer is still difficult, and the sensitivity, the low-dose detection capability and the spatial resolution of the radiation detector are affected; perovskite materials are easy to decompose when contacted with water and oxygen, resulting in poor device stability and the like.

Therefore, the novel radiation perovskite type radiation detector capable of simultaneously meeting the requirements of large-area preparation, high stability, high detection performance and low working voltage is explored, and has profound significance and practical value.

Disclosure of Invention

In view of the above, in order to break through the technical problem that the size of the radiation detector is limited due to crystallization performance of the traditional perovskite type radiation detector, and meanwhile, to develop the radiation detector with high stability and high detection performance under low working voltage, the present disclosure provides a perovskite type radiation detector based on schottky junctions and a preparation method thereof.

In one aspect of the present disclosure, a method for fabricating a perovskite radiation detector based on schottky junctions is provided, comprising:

the carbon slurry is coated on a first substrate to form a film, and the film is annealed to obtain a carbon electrode layer;

spreading the carbon slurry on a second substrate to form a film, soaking the film in an organic solvent for more than 10 minutes, stripping the carbon film from the second substrate, and standing the film in air until the organic solvent is completely volatilized to obtain a porous carbon film;

dissolving organic ammonium salt or cesium salt and metal halide in a polar organic solvent to obtain a perovskite solution, pouring the perovskite solution on a porous carbon film, enabling the perovskite solution to permeate into the porous carbon film under the pressure condition, and annealing to obtain a radiation absorption layer composed of a porous carbon-perovskite composite material;

placing a radiation absorbing layer on the carbon electrode layer, and bonding the radiation absorbing layer to the carbon electrode layer under pressure;

coating perovskite solution on the radiation absorbing layer, and annealing to obtain a compact perovskite layer;

coating an organic hole injection material on the compact perovskite layer to obtain a hole injection layer;

and forming a film on the hole injection layer by conducting metal through thermal evaporation treatment to form a top electrode layer, thereby obtaining the perovskite radiation detector based on the Schottky junction.

According to an embodiment of the present disclosure, the carbon slurry is knife coated on the first substrate to form a film, and the annealing conditions include: the annealing temperature range is 100-120 ℃, and the annealing time range is 10-30 min.

According to embodiments of the present disclosure, the metal halide includes one or more of lead iodide, tin iodide, copper iodide, manganese iodide, lead bromide, tin bromide, copper bromide, manganese bromide, lead chloride, tin chloride, copper chloride, manganese chloride;

the organic ammonium salt comprises one or more of methylamine iodide, formamidine iodide, methylamine bromide, formamidine bromide, methylamine chloride and formamidine chloride;

cesium salts include one or more of cesium iodide, cesium bromide, cesium chloride;

the stoichiometric ratio of the organic ammonium salt (or cesium salt) to the metal halide comprises 2:1 to 1:1.

According to an embodiment of the present disclosure, in the infiltration process of the perovskite solution into the porous carbon film, the pressure condition includes 1.1 to 5bar, and the annealing treatment condition includes: the annealing temperature range is 80-180 ℃, and the annealing time range is 2-10 h.

According to embodiments of the present disclosure, the pressure conditions include a pressurizing range of greater than 0.01Mpa during the bonding of the radiation absorbing layer and the carbon electrode layer;

the perovskite solution is coated on the radiation absorbing layer, and the annealing treatment conditions comprise: the annealing temperature range is 50-180 ℃, and the annealing time range is 5-30 min.

According to an embodiment of the present disclosure, the organic hole injection material includes one of: polytrianiline, poly [ bis (4-phenyl) (2, 4, 6-trimethylphenyl) amine ], polyvinylcarbazole.

In another aspect of the disclosure, a perovskite radiation detector based on schottky junction prepared by the method is provided, including:

a carbon electrode layer for conducting holes to output an electrical signal;

the radiation absorbing layer is formed on the carbon electrode layer, is prepared from a porous carbon-perovskite composite material, and is provided with a Schottky junction capable of forming a built-in electric field and is used for generating carriers in response to X rays;

the compact perovskite layer is formed on the radiation absorption layer and is used for isolating the radiation absorption layer from the hole injection layer and preventing the radiation detector from electric leakage;

the cavity injection layer is formed on the compact perovskite layer and is used for injecting cavities to maintain the electric neutrality of the internal structure of the perovskite radiation detector and form a loop; and

and the top electrode layer is formed on the hole injection layer and is used for receiving an external bias voltage to guide carriers generated by the radiation absorption layer to move towards the carbon electrode layer so as to assist in extracting the carriers generated by the radiation absorption layer.

According to embodiments of the present disclosure, the carriers generated by the radiation absorbing layer include photogenerated holes and photogenerated electrons.

According to the embodiment of the disclosure, holes are extracted by the carbon electrode layer under the action of a built-in electric field of the schottky junction, and photo-generated electrons are restrained in the radiation absorbing layer under the obstruction of the schottky junction.

In another aspect of the present disclosure, a perovskite radiation detection array is presented, comprising a plurality of the above-described radiation detectors distributed uniformly.

According to an embodiment of the disclosure, the disclosure provides a perovskite radiation detector based on a Schottky junction and a preparation method thereof. By preparing the porous carbon-perovskite composite material, the radiation absorbing layer with the Schottky junction is constructed, the radiation absorbing layer is not limited by the growth size of perovskite single crystal materials, and the radiation absorbing layer with a large area can be prepared and obtained, so that the radiation absorbing layer has good uniformity and spatial resolution. Meanwhile, the perovskite type radiation detector with stable working performance and good detection resolution performance can be prepared by a simple preparation method.

According to the radiation detector provided by the embodiment of the disclosure, the radiation absorption layer is made of the porous carbon-perovskite composite material with the Schottky junction, so that the working voltage of the radiation detector can be reduced while the detection performance of the radiation detector is improved, and the perovskite radiation detector has excellent performance and stability. The low operating voltage allows the radiation detector with a porous structure to be applied to a portable device, thereby realizing faster and more accurate portable radiation detection. At the same time, the large area, uniform porous carbon-perovskite radiation detection array exhibits excellent uniformity and spatial resolution.

Drawings

FIG. 1 is a device structure and operational schematic diagram comparison of a conventional layered semiconductor radiation detector and a Schottky junction-based perovskite radiation detector of the present disclosure;

FIG. 2 is a flow chart of the fabrication of a Schottky junction based perovskite radiation detector of the present disclosure;

FIG. 3 is a surface topography scanning electron microscope image of a porous carbon film prepared in an embodiment of the present disclosure;

FIG. 4 is a cross-sectional morphology scanning electron microscope image of a porous carbon film prepared in an embodiment of the present disclosure;

FIG. 5 is a scanning electron microscope image of the surface morphology of the porous carbon-perovskite composite material prepared in the examples of the present disclosure;

FIG. 6 is a cross-sectional morphology scanning electron microscope image of the porous carbon-perovskite composite material prepared in the examples of the present disclosure;

fig. 7 is a schematic structural diagram of a schottky junction-based perovskite radiation detector prepared in the present disclosure;

FIG. 8 is a plot of carrier separation observed for porous carbon-perovskite composites using a Kelvin probe force microscope in the present disclosure;

FIG. 9 is a graph of the sensitivity variation of a Schottky junction based perovskite radiation detector of the present disclosure at different biases;

FIG. 10 is a graph of sensitivity variation of a conventional layered perovskite radiation detector under different biases;

FIG. 11 is a signal-to-noise ratio comparison of a perovskite radiation detector based on Schottky junctions and a perovskite radiation detector of conventional layered structure in the present disclosure;

FIG. 12 is a graph of current drift tests for a Schottky junction based perovskite radiation detector of the present disclosure;

FIG. 13 is a graph of an irradiance stability test for a Schottky junction based perovskite radiation detector of the present disclosure;

FIG. 14 is a graph of an operational stability test of a Schottky junction based perovskite radiation detector of the present disclosure under pulsed X-rays;

fig. 15 is a long term stability test chart of a schottky junction-based perovskite radiation detector of the present disclosure in a nitrogen glove box storage environment;

FIG. 16 is a schematic diagram of the radiation alarm device prepared in example 1 of the present disclosure;

FIG. 17 is a graph comparing the response time of the radiation alarm device prepared in example 1 of the present disclosure with a radiation alarm device based on a GM counter tube;

FIG. 18 is a graph comparing the energy response of the radiation alarm device prepared in example 1 of the present disclosure to low energy X-rays with a radiation alarm device based on a GM counter tube;

FIG. 19 is a graph showing dark current profiles of different detection pixels of a perovskite radiation detection array prepared as described in example 2 of the present disclosure in a dark environment;

FIG. 20 is a photocurrent distribution diagram of the X-ray response of different detection pixels irradiated with X-rays by the perovskite radiation detection array prepared in example 2 of the present disclosure;

FIG. 21 is an image of a lead wire pair plate of a perovskite radiation detection array prepared as example 2 of the present disclosure;

fig. 22 is a graph of the spatial resolution of a perovskite radiation detection array prepared in example 2 of the present disclosure.

Detailed Description

For the purposes of promoting an understanding of the principles and advantages of the disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same.

The endpoints of the ranges and any values disclosed in this disclosure are not limited to the precise range or value, and such range or value should be understood to encompass values approaching those range or value. For numerical ranges, one or more new numerical ranges may be obtained in combination with each other between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, and are to be considered as specifically disclosed in this disclosure.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and/or the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.

It is to be noted that unless otherwise defined, technical or scientific terms used in the present disclosure should be taken in a general sense as understood by one of ordinary skill in the art to which the present disclosure pertains. If, throughout, reference is made to "first," "second," etc., the description of "first," "second," etc., is used merely for distinguishing between similar objects and not for understanding as indicating or implying a relative importance, order, or implicitly indicating the number of technical features indicated, it being understood that the data of "first," "second," etc., may be interchanged where appropriate.

Fig. 1 is a device structure and operational schematic diagram comparison of a conventional layered semiconductor radiation detector and a perovskite radiation detector based on schottky junctions in the present disclosure.

As shown in fig. 1, in the perovskite radiation detector with the conventional layered structure, photo-generated carriers generated by the radiation absorbing layer need to migrate the distance of the thickness of the radiation detector device to obtain higher detection sensitivity. Therefore, it is often necessary to apply an operating voltage of several tens to several hundreds volts to the radiation detector, and the larger operating voltage may further exacerbate ion movement, reduce device stability, and limit the use of perovskite semiconductor radiation detectors in portable radiation detection devices.

In the perovskite radiation detector based on the schottky junction, which is provided by the disclosure, a porous carbon-perovskite composite material is used as the radiation absorbing layer 2, and the schottky junction can be formed at the interface of the carbon material and the perovskite material, and the schottky junction can form a space charge region for blocking electrons and extracting holes. Namely, when the perovskite material generates two carriers of photo-generated holes and photo-generated electrons under the action of X rays, the photo-generated holes can be spontaneously collected by the carbon electrode under the action of an electric field built in the Schottky junction, and meanwhile, the photo-generated electrons are bound in the perovskite material. The photo-generated carrier collection of the device is not dependent on the applied voltage, so that the working voltage of the device is greatly reduced. Meanwhile, the bound photo-generated electrons can play a role of photoconductive gain, so that the performance of the radiation detector is greatly improved.

Fig. 2 is a flow chart of the fabrication of a schottky junction-based perovskite radiation detector of the present disclosure.

In one aspect of the present disclosure, a method for preparing a perovskite radiation detector based on schottky junctions is provided, as shown in fig. 2, wherein steps S1 and S2 are performed without strict sequential order, the preparation method includes:

s1: the carbon slurry is coated on a first substrate to form a film, and the film is annealed to obtain a carbon electrode layer 1;

s2: spreading the carbon slurry on a second substrate to form a film, soaking the film in an organic solvent for more than 10 minutes, stripping the carbon film from the second substrate, and standing the film in air until the organic solvent is completely volatilized to obtain a porous carbon film;

s3: dissolving metal halide and organic ammonium salt in a polar organic solvent to obtain a perovskite solution, pouring the perovskite solution on a porous carbon film, allowing the perovskite solution to permeate into the porous carbon film under the pressure condition, and annealing to obtain a radiation absorbing layer 2 composed of a porous carbon-perovskite composite material;

s4: placing the radiation absorbing layer 2 on the carbon electrode layer 1, and bonding the radiation absorbing layer 2 with the carbon electrode layer 1 under pressure;

s5: coating perovskite solution on the radiation absorbing layer 2, and annealing to obtain a compact perovskite layer 3;

s6: coating an organic hole injection material on the compact perovskite layer 3 to obtain a hole injection layer 4;

s7: and forming a film on the hole injection layer 4 through thermal evaporation treatment by conducting metal to form a top electrode layer 5, thereby obtaining the perovskite radiation detector based on the Schottky junction.

According to an embodiment of the present disclosure, in step S1, the carbon paste is knife coated on the first substrate to form a film, and the annealing conditions include: the annealing temperature range includes 100-120 ℃, e.g., alternatively 100 ℃, 110 ℃, 120 ℃; the annealing time range includes 10 to 30 minutes, for example, 10 minutes, 20 minutes, 30 minutes may be selected.

According to the embodiment of the disclosure, a compact carbon electrode material can be obtained under the annealing condition, and the compact carbon electrode material has good carrier transmission and electric signal output capabilities.

According to the embodiment of the disclosure, in step S2, the organic solvent may be selected from ethanol, diethyl ether, and acetone, and the carbon film is dip-coated to form a porous carbon film material.

FIG. 3 is a surface topography scanning electron microscope image of a porous carbon film prepared in an embodiment of the present disclosure.

FIG. 4 is a cross-sectional morphology scanning electron microscope image of a porous carbon film prepared in an embodiment of the present disclosure.

According to the embodiment of the disclosure, as shown in fig. 3 and 4, the porous carbon film material prepared in the disclosure has gaps and good permeability. The surface of the porous carbon film has uniformly distributed pores with the diameter of 200nm-2 mu m, thereby facilitating the injection of perovskite solution. Meanwhile, the aperture in the range from hundred nanometers to micrometers is matched with the width of the built-in electric field of the Schottky junction, so that the extraction of photo-generated holes is facilitated. The internal pore canal is uniformly distributed and has larger porosity, thus guaranteeing the uniform distribution of perovskite materials.

the stoichiometric ratio of the organic ammonium salt or cesium salt to the metal halide comprises 2:1 to 1:1.

According to the embodiment of the disclosure, the metal halide perovskite material is used as a novel semiconductor material with excellent performance, has elements with higher atomic numbers such as cesium, lead and iodine, can effectively absorb high-energy rays such as X-rays, has excellent photoelectric performance such as large carrier-life product and high defect tolerance, and is suitable for being applied to the field of radiation detection.

FIG. 5 is a scanning electron microscope image of cross-sectional morphology of porous carbon-perovskite composite materials prepared in examples of the present disclosure at different resolutions.

According to the embodiment of the disclosure, as shown in fig. 5, it can be seen in an electron microscope image of the disclosure that the porous carbon-perovskite composite material with compact combination and smooth morphology is successfully synthesized, wherein the perovskite material is embedded into the porous carbon material and is tightly combined, and the perovskite material has coarse grains and good quality

According to an embodiment of the present disclosure, the pressure conditions include a pressurizing range of more than 0.01Mpa during the bonding of the radiation absorbing layer 2 and the carbon electrode layer 1;

the perovskite solution is coated on the radiation absorbing layer 2, and the annealing treatment conditions include: the annealing temperature range is 50-180 ℃, and the annealing time range is 5-30 min.

Fig. 6 is a scanning electron microscope image of the surface morphology of the dense perovskite layer 3 prepared in the examples of the present disclosure.

According to the embodiment of the disclosure, as shown in fig. 6, a dense perovskite material can be obtained under the annealing condition, and as can be seen from the electron microscope image, the dense perovskite layer 3 is completely covered on the radiation absorbing layer 2, and no bare carbon is present, so that the dense perovskite layer 3 has good breakdown preventing performance.

Fig. 7 is a schematic structural diagram of a schottky junction-based perovskite radiation detector prepared in the present disclosure.

In another aspect of the present disclosure, a perovskite radiation detector based on schottky junction prepared by the above method is provided, as shown in fig. 7, including:

a carbon electrode layer 1 for conducting holes to output an electrical signal;

the radiation absorbing layer 2 is formed on the carbon electrode layer 1, and the radiation absorbing layer 2 is prepared from a porous carbon-perovskite composite material and is provided with a Schottky junction capable of forming a built-in electric field and is used for generating carriers in response to X rays;

the compact perovskite layer 3 is formed on the radiation absorption layer 2 and is used for isolating the radiation absorption layer 2 from the hole injection layer 4 and preventing the radiation detector from electric leakage;

the hole injection layer 4 is formed on the compact perovskite layer 3 and is used for injecting holes to maintain the electric neutrality of the internal structure of the perovskite radiation detector and form a loop; and

and a top electrode layer 5 formed on the hole injection layer 4 for receiving an external bias voltage to guide the carriers generated by the radiation absorbing layer 2 to move towards the carbon electrode layer 1, and assist in extracting the carriers generated by the radiation absorbing layer 2.

According to the radiation detector provided by the embodiment of the disclosure, the radiation absorption layer is made of the porous carbon-perovskite composite material with the Schottky junction, so that the working voltage of the radiation detector can be reduced while the detection performance of the radiation detector is improved, and the perovskite radiation detector has excellent performance and stability. The low operating voltage allows the radiation detector with a porous structure to be applied to a portable device, thereby realizing faster and more accurate portable radiation detection.

According to an embodiment of the present disclosure, the carriers generated by the radiation absorbing layer 2 include photogenerated holes and photogenerated electrons.

According to the embodiment of the disclosure, holes are extracted by the carbon electrode layer 1 under the action of the built-in electric field of the schottky junction, and photo-generated electrons are restrained in the radiation absorbing layer 2 under the obstruction of the schottky junction.

According to the embodiment of the disclosure, under the action of an electric field built in the schottky junction, photo-generated holes can be spontaneously collected by the carbon electrode, and meanwhile, photo-generated electrons are bound in the perovskite material. The photo-generated carrier collection of the device is not dependent on the applied voltage, so that the working voltage of the device is greatly reduced. Meanwhile, the bound photo-generated electrons can play a role of photoconductive gain, so that the performance of the radiation detector is greatly improved.

According to embodiments of the present disclosure, a large-area, uniform perovskite radiation detection array has excellent uniformity and spatial resolution.

It should be noted that the described embodiments are only some embodiments of the present disclosure, and not all embodiments. Based on the embodiments in this disclosure, other embodiments that may be obtained by one of ordinary skill in the art without making any inventive effort are within the scope of the present disclosure.

Example 1

In embodiment 1, a perovskite radiation detector based on a schottky junction and a preparation method thereof are provided, and a perovskite X-ray detector and a portable radiation alarm are prepared, which specifically comprise the following steps:

s1: and respectively ultrasonically cleaning Indium Tin Oxide (ITO) conductive glass serving as a substrate material by using detergent, deionized water, acetone and absolute ethyl alcohol, and then storing the cleaned ITO substrate in a 70 ℃ oven for drying.

The conductive carbon paste was uniformly coated on an ITO conductive glass substrate using a knife coating method, and annealed at 150 ℃ for 20min in air to obtain a dense carbon electrode layer 1.

S2: the conductive carbon paste is uniformly coated on a hydrophobic substrate by using a knife coating method, and is placed in absolute ethyl alcohol to be soaked for 5 hours, the carbon film is peeled off from the substrate and then is kept stand in the air for 5 hours, and the absolute ethyl alcohol is naturally volatilized to obtain the porous carbon film.

S3: methylamine iodide solution (MAI), lead iodide (PbI) ₂ ) And methylamine chloride (MACl) at 10:10:1 in 2-methoxyethanol (2-ME) to form a perovskite solution having a concentration of 2.2M. And (2) dripping the perovskite solution onto the porous carbon film prepared in the step (S2) to form a composite material, and applying air pressure of 1.5bar to improve the permeability of the perovskite solution. The porous carbon-perovskite composite film was annealed at a temperature of 120℃and a pressure of 0.02MPa for 2 hours to obtain a radiation absorbing layer 2.

S4: the casting process in the step S3 was performed for 3 cycles in total, and after the third perovskite solution infiltration process was completed, the radiation absorbing layer 2 prepared in the step S3 was attached to the dense carbon electrode 1 prepared in the step S1, and annealed at 120 ℃ under a pressure of 0.02MPa for 2 hours.

S5: the perovskite solution is subjected to spin-coating treatment on the radiation absorbing layer 2 prepared in step S3 at room temperature to obtain a dense perovskite layer 3. Wherein 50. Mu.L of the perovskite solution was used each time, the spin Tu Yi rotation speed was 2000r/min, each time spin was performed for 45s, nitrogen quenching was applied at the 4 th second from the start of spin coating, and then the dense perovskite film was annealed at 120℃for 20 minutes, and this process was repeated twice.

S6: polytriphenylamine (poly-TPD) was dissolved in Chlorobenzene (CB) as an organic hole injection material to give a 6mg/ml solution of polytrianiline. The hole injection layer 4 is obtained by spin-coating a solution of polytrianiline on the dense perovskite layer 3 prepared in step S5 at room temperature. Wherein, each time the hole transport layer 4 was spin-coated with 30 μl of the polytrianiline solution, the spin Tu Yi rotation speed was 1000r/min, each time spin-coated for 30s, and then the hole injection layer 4 was annealed at 120 ℃ for 20 minutes.

S7: on the hole injection layer 4, 8nm thick molybdenum trioxide (MoO) was sequentially deposited ₃ ) And a metal electrode with an area of 2mm x 2mm to form a top electrode layer 5, to obtain the perovskite radiation detector based on the schottky junction.

S8: and (3) assembling the perovskite radiation detector, the current amplification module, the alarm judgment module and the alarm which are based on the Schottky junction and are prepared in the step (S7) to obtain the portable radiation alarm.

Example 2

Using the portable perovskite radiation detector based on schottky junction porous structure and the preparation method thereof in example 2, a perovskite X-ray detection array was prepared, specifically comprising the following steps:

S5: the perovskite solution was subjected to a coating treatment by using a knife coating method on the radiation absorbing layer 2 prepared in step S3 at room temperature to obtain a dense perovskite layer 3. Wherein 50. Mu.L of the perovskite solution was used each time, the perovskite solution was coated at a speed of 50mm/s, the gap between the doctor blade and the radiation absorbing layer 2 was 150. Mu.m, and the dense perovskite layer 3 was annealed at 120℃for 20 minutes after air-knife quenching.

S6: polytriphenylamine (poly-TPD) was dissolved in Chlorobenzene (CB) as an organic hole injection material to give a 6mg/ml solution of polytrianiline. The hole injection layer 4 is obtained by spin-coating a solution of polytrianiline on the dense perovskite layer 3 prepared in step S5 at room temperature. Wherein, each time the hole transport layer was spin-coated with 30 μl of the polytrianiline solution, the spin Tu Yi rotation speed was 1000r/min, each time spin-coated for 30s, and then the hole injection layer 4 was annealed at 120 ℃ for 20 minutes.

S7: on the hole injection layer 4, 8nm thick molybdenum trioxide (MoO) was sequentially deposited ₃ ) And metal electrodes with pixel sizes of 500 μm by 500 μm or 150 μm by 150 μm to obtain perovskite radiation detection arrays.

Test example 1

The porous carbon-perovskite composite material prepared in the present disclosure was observed for carrier separation under X-ray irradiation under a Kelvin Probe Force Microscope (KPFM) through a Contact Potential Difference (CPD) between the sample surface and the cantilever.

Fig. 8 is a diagram of carrier separation observed for porous carbon-perovskite composites using a kelvin probe force microscope in the present disclosure.

As shown in fig. 8, the kelvin probe force microscope can compare the changes of the work functions of different areas of the thin film before and after illumination, and the work functions of the perovskite material and the carbon material are found to have obvious changes before and after illumination, which indicates that the carrier separation occurs at the interface of the perovskite and the carbon.

Test example 2

And testing the detection performance of the perovskite radiation detector based on the Schottky junction.

Fig. 9 is a graph of the sensitivity variation of the schottky junction based perovskite radiation detector of the present disclosure at different biases.

Fig. 10 is a graph of sensitivity variation of a conventional layered perovskite radiation detector under different biases.

As shown in fig. 9 and fig. 10, compared with the perovskite radiation detector with the traditional layered structure, the perovskite radiation detector based on the schottky junction provided by the present disclosure can realize more sensitive detection performance under the action of lower external bias, which proves that the performance of the perovskite radiation detector based on the schottky junction provided by the present disclosure is obviously improved.

The proposed externally-applied bias voltage range of the perovskite radiation detector based on the Schottky junction is-0.5 to-1V, and the sensitivity of the detector is optimal in the range.

Fig. 11 is a signal-to-noise ratio comparison of a perovskite radiation detector based on schottky junctions and a perovskite radiation detector of conventional layered structure in the present disclosure.

As shown in fig. 11, the signal-to-noise ratio of the perovskite radiation detector based on the schottky junction proposed by the present disclosure is significantly higher than that of the perovskite radiation detector with the conventional layered structure, which proves that the perovskite radiation detector based on the schottky junction proposed by the present disclosure has a stronger capability of receiving useful signals.

Test example 3

The perovskite radiation detector based on the Schottky junction prepared in the method is subjected to device stability test.

Perovskite materials are brittle and sensitive to environmental changes, and are easy to oxidize and not resistant to high temperature, so that the radiation detector has short service life and poor stability. The material of the radiation absorbing layer 2 in the perovskite radiation detector based on the schottky junction in the present disclosure is a porous carbon-perovskite composite material, and the perovskite material is embedded into the porous carbon material to form large grains with more stable performance. At the same time, the carbon material and the perovskite material form a schottky junction, and the energy band of the perovskite material at the interface bends to form a high potential energy region, namely a schottky barrier, and electrons must have energy higher than the schottky barrier to flow into the metal beyond the barrier, so that electrons in the perovskite material are prevented from flowing into the carbon material.

Fig. 12 is a graph of current drift tests for a schottky junction based perovskite radiation detector of the present disclosure.

As shown in fig. 12, the perovskite radiation detector based on schottky junction in the present disclosure can maintain stable current for a long time when the external bias voltage is-1V, which proves that the perovskite radiation detector has good operation stability.

Fig. 13 is a graph of an irradiation stability test of a schottky junction-based perovskite radiation detector of the present disclosure.

As shown in fig. 13, the radiation absorbing layer 2 in the perovskite radiation detector based on schottky junction in the present disclosure can respond stably to external radiation to output an electrical signal, and its sensitivity can ensure stability of sensitivity over a long period of time.

Fig. 14 is a graph of an operational stability test of a schottky junction based perovskite radiation detector of the present disclosure under pulsed X-rays.

As shown in fig. 14, under the action of pulsed X-rays, the perovskite radiation detector based on schottky junctions in the present disclosure works stably with good repeatability.

Fig. 15 is a graph of long term stability testing of a schottky junction-based perovskite radiation detector of the present disclosure in a nitrogen glove box storage environment.

As shown in fig. 15, the schottky junction-based perovskite radiation detector of the present disclosure maintains stability over time in a nitrogen atmosphere with sensitivity maintained at substantially the same level.

Test example 4

Performance testing was performed on the portable radiation alarm device prepared in example 1 of the present disclosure.

Fig. 16 is a schematic diagram of the composition of the radiation alarm device prepared in example 1 of the present disclosure.

As shown in fig. 16, the radiation alarm is assembled by a perovskite radiation detector based on schottky junction, a current amplifying module, an alarm judging module and an alarm.

Gas discharge counting tubes are a common type of nuclear radiation detector. The Geiger-muller counter tube (GM tube) is a pulse-recording electronic counter, is commonly used for high-energy radiation, has the characteristics of large pulse amplitude, low manufacturing cost and convenient use, but has the characteristics of small temperature range of normal operation, long resolution time and spurious counting.

Fig. 17 is a graph comparing response time of the radiation alarm device prepared in example 1 of the present disclosure with a GM-based radiation alarm device.

As shown in fig. 17, the response speed of the radiation alarm device of the perovskite detector based on schottky junction prepared in the embodiment 1 of the disclosure is significantly faster than that of the radiation alarm device of the GM counter tube, and the response time is improved by 24 times compared with that of the GM counter tube.

Fig. 18 is a graph comparing the energy response of the radiation alarm prepared in example 1 of the present disclosure to low energy X-rays for a GM-counter based radiation alarm.

As shown in fig. 18, the radiation alarm device of the perovskite detector based on schottky junction prepared in the embodiment 1 of the present disclosure can have more accurate response to low energy X-rays. The radiation alarm device based on the perovskite detector of the Schottky junction, which is prepared in the embodiment 1 of the present disclosure, is proved to have detection performance and response speed superior to those of the conventional GM counter tube.

Test example 5

Performance testing was performed on the perovskite radiation detection array prepared in example 2 of the present disclosure.

The perovskite radiation detection array refers to a device which is formed by a plurality of schottky junction perovskite detectors which are sensitive to radiation and are prepared in the embodiment 2 of the disclosure and are arranged according to rules, the perovskite radiation detection array has signal transmission and processing capacity, and the array in the embodiment 2 of the disclosure adopts a two-dimensional area array structure. When the target is imaged, the plurality of radiation detectors respectively and simultaneously receive the radiation and output corresponding electric signals, so that the array device can increase the residence time of the radiation compared with the single radiation detector, improve the signal-to-noise ratio of the system and greatly reduce the complexity of the detection system.

Fig. 19 is a graph of dark current distribution of different detection pixels in a dark environment of a perovskite radiation detection array prepared in example 2 of the present disclosure.

Fig. 20 is a photocurrent distribution diagram of X-ray responses of different detection pixels of the perovskite radiation detection array prepared in example 2 of the present disclosure under X-ray irradiation.

As shown in fig. 19 and 20, the schottky junction-based perovskite radiation detection array prepared in example 2 of the present disclosure exhibited good uniformity in both dark environments and under X-ray irradiation.

Fig. 21 is an image of a lead wire pair plate of a perovskite radiation detection array prepared in example 2 of the present disclosure.

As shown in fig. 21, the left side is a lead wire pair plate and the right side is an imaging chart. The perovskite radiation detection array based on the Schottky junction, which is prepared in the embodiment 2 of the present disclosure, is used for line-scan imaging of lead wire on a board, and the imaging effects have extremely high definition at the resolutions of 2.5lp/mm, 3.4lp/mm, 4.6lp/mm and 5.5 lp/mm.

The perovskite radiation detection array with the pixel size of 150 μm×150 μm prepared in example 2 of the present disclosure was selected for the spatial resolution test. The spatial resolution of the traditional commercial CsI: tl flat panel detection array is about 3 lp/mm.

As shown in FIG. 22, the spatial resolution of the perovskite radiation detection array prepared in the embodiment 2 of the disclosure is about 5lp/mm, which proves that the spatial resolution of the perovskite radiation detection array is superior to that of a commercial CsI: tl flat panel detection array, and the perovskite radiation detection array has excellent spatial imaging capability.

While the foregoing is directed to embodiments of the present disclosure, other and further details of the invention may be had by the present application, it is to be understood that the foregoing description is merely exemplary of the present disclosure and that no limitations are intended to the scope of the disclosure, except insofar as modifications, equivalents, improvements or modifications may be made without departing from the spirit and principles of the present disclosure.

Claims

1. A method of making a schottky junction based perovskite radiation detector comprising:

the carbon slurry is coated on a first substrate to form a film, and the film is annealed to obtain a carbon electrode layer (1);

spreading carbon slurry on a second substrate to form a film, soaking the film in an organic solvent for more than 10 minutes, stripping the carbon film from the second substrate, and standing the film in air until the organic solvent is completely volatilized to obtain a porous carbon film;

dissolving organic ammonium salt or cesium salt and metal halide in a polar organic solvent to obtain a perovskite solution, pouring the perovskite solution on the porous carbon film, allowing the perovskite solution to permeate into the porous carbon film under the pressure condition, and annealing to obtain a radiation absorbing layer (2) composed of a porous carbon-perovskite composite material;

-placing the radiation absorbing layer (2) on the carbon electrode layer (1), bonding the radiation absorbing layer (2) to the carbon electrode layer (1) under pressure;

coating the perovskite solution on the radiation absorbing layer (2), and annealing to obtain a compact perovskite layer (3);

coating an organic hole injection material on the compact perovskite layer (3) to obtain a hole injection layer (4);

and forming a film on the hole injection layer (4) through thermal evaporation treatment to form a top electrode layer (5) so as to obtain the perovskite radiation detector based on the Schottky junction.

2. The method of claim 1, wherein doctor blading the carbon slurry onto the first substrate to form a film, the annealing conditions comprising: the annealing temperature range is 100-120 ℃, and the annealing time range is 10-30 min.

3. The method of claim 1, wherein,

the metal halide comprises one or more of lead iodide, tin iodide, copper iodide, manganese iodide, lead bromide, tin bromide, copper bromide, manganese bromide, lead chloride, tin chloride, copper chloride and manganese chloride;

the cesium salt comprises one or more of cesium iodide, cesium bromide and cesium chloride

4. The method of claim 1, wherein the pressure conditions during infiltration of the perovskite solution into the porous carbon film comprise 1.1-5 bar, and the annealing conditions comprise: the annealing temperature range is 80-180 ℃, and the annealing time range is 2-10 h.

5. The method of claim 1, wherein,

in the process of combining the radiation absorbing layer (2) and the carbon electrode layer (1), the pressure condition comprises a pressurizing range of more than 0.01Mpa;

-coating the perovskite solution on the radiation absorbing layer (2), the annealing treatment conditions comprising: the annealing temperature range is 50-180 ℃, and the annealing time range is 5-30 min.

6. The method of claim 1, wherein the organic hole injection material comprises one of: polytrianiline, poly [ bis (4-phenyl) (2, 4, 6-trimethylphenyl) amine ], polyvinylcarbazole.

7. A schottky junction-based perovskite radiation detector prepared by the method according to any one of claims 1 to 6, comprising, in order:

a carbon electrode layer (1) for conducting holes to output an electrical signal;

a radiation absorbing layer (2) formed on the carbon electrode layer (1), the radiation absorbing layer (2) being made of a porous carbon-perovskite composite material, having a schottky junction capable of forming a built-in electric field for generating carriers in response to X-rays;

a compact perovskite layer (3) formed on the radiation absorption layer (2) and used for isolating the radiation absorption layer (2) from the hole injection layer (4) and preventing the radiation detector from electric leakage;

a hole injection layer (4) formed on the dense perovskite layer (3) for injecting holes to maintain the electrical neutrality of the internal structure of the perovskite radiation detector and form a loop; and

and the top electrode layer (5) is formed on the hole injection layer (4) and is used for receiving an external bias voltage to guide carriers generated by the radiation absorption layer (2) to move towards the carbon electrode layer (1) so as to assist in extracting the carriers generated by the radiation absorption layer (2).

8. The radiation detector according to claim 7, wherein the carriers generated by the radiation absorbing layer (2) comprise photo-generated holes and photo-generated electrons.

9. The radiation detector according to claim 7, wherein the holes are extracted by a carbon electrode layer (1) under the influence of a built-in electric field of the schottky junction, and the photogenerated electrons are bound in the radiation absorbing layer (2) under the influence of the schottky junction.

10. A perovskite radiation detection array comprising a plurality of radiation detectors as claimed in any one of claims 7 to 9, distributed evenly.