阅读说明：本技术 全无机卤素钙钛矿单晶x射线探测器及其制备方法 (All-inorganic halogen perovskite single crystal X-ray detector and preparation method thereof ) 是由 杨斌 李俊驰 于 2019-09-24 设计创作，主要内容包括：本发明涉及一种全无机卤素钙钛矿单晶X射线探测器,其包括钙钛矿单晶以及位于钙钛矿单晶两侧相对设置的电极,所述钙钛矿单晶的分子式为Cs<Sub>(1-x)</Sub>Rb<Sub>x</Sub>Pb(Br<Sub>(1-y)</Sub>I<Sub>y</Sub>)<Sub>3</Sub>,其中0≤x≤0.1,0≤y≤0.3。相比较现有技术,本发明的全无机卤素钙钛矿单晶的制备过程更简单、成本也更低。相比较于多晶钙钛矿薄膜,本发明使用的钙钛矿单晶具有载流子迁移率更高、载流子寿命更长、稳定性更好等优势,因而使X射线探测器性能更优。(The invention relates to an all-inorganic halogen perovskite single crystal X-ray detector, which comprises a perovskite single crystal and electrodes which are oppositely arranged and positioned on two sides of the perovskite single crystal, wherein the molecular formula of the perovskite single crystal is Cs (1‑x) Rb x Pb(Br (1‑y) I y ) 3 Wherein x is more than or equal to 0 and less than or equal to 0.1, and y is more than or equal to 0 and less than or equal to 0.3. Compared with the prior art, the preparation process of the all-inorganic halogen perovskite single crystal is simpler and has lower cost. Compared with a polycrystalline perovskite thin film, the perovskite single crystal used by the invention has the advantages of higher carrier mobility, longer carrier service life, better stability and the like, so that the X-ray detector has better performance.)

1. The utility model provides an all inorganic halogen perovskite single crystal X ray detector, its includes perovskite single crystal and is located the relative electrode that sets up in perovskite single crystal both sides, its characterized in that: the molecular formula of the perovskite single crystal is Cs_(1-x)Rb_xPb(Br_(1-y)I_y)₃Wherein x is more than or equal to 0 and less than or equal to 0.1, and y is more than or equal to 0 and less than or equal to 0.3.

2. An all-inorganic halogen perovskite single crystal X-ray detector according to claim 1, characterized in that: the electrode material is a conductive film of gold, silver, copper or aluminum and the like.

3. An all-inorganic halogen perovskite single crystal X-ray detector according to claim 2, characterized in that: the X-ray detector consists of a perovskite monocrystal and electrodes arranged on two sides of the perovskite monocrystal, wherein the electrodes are conductive thin films plated on two opposite side surfaces of the perovskite monocrystal respectively.

4. An all-inorganic halogen perovskite single crystal X-ray detector according to claim 2, characterized in that: the X-ray detector consists of a perovskite single crystal, an electron transport layer, an interface modification layer and two electrodes; one side surface of the perovskite single crystal is plated with a conductive film to form an electrode, the other side surface of the perovskite single crystal is sequentially plated with an electron transmission layer and an interface modification layer from inside to outside, and the interface modification layer is further plated with a conductive film to form another electrode.

5. An all-inorganic halogen perovskite single crystal X-ray detector according to claim 4, characterized in that: the electron transport layer material is fullerene or a derivative thereof, and the interface modification layer material is an electron transport material.

6. An all-inorganic halogen perovskite single crystal X-ray detector according to any one of claims 1 to 4, characterized in that: the molecular formula of the perovskite single crystal is Cs_(1-x)Rb_xPbBr₃Wherein x is more than or equal to 0 and less than 0.1.

7. A preparation method of the all-inorganic halogen perovskite single crystal X-ray detector comprises the following steps:

s1, preparing all-inorganic halogen perovskite single crystal: growth of CsPbBr by solution method₃Adding soluble salt of rubidium halide into solution of monocrystal to obtain compound with molecular formula of Cs_(1-x)Rb_xPb(Br_(1-y)I_y)₃Wherein x is more than or equal to 0 and less than or equal to 0.1, and y is more than or equal to 0 and less than or equal to 0.3;

s2, preparing a single crystal X-ray detector: and selecting two opposite surfaces of the all-inorganic halogen perovskite single crystal, and respectively forming electrodes on the two opposite surfaces, or forming an electrode on one surface and sequentially forming an electron transmission layer, an interface modification layer and an electrode on the other surface.

8. The method of claim 7, wherein:

in the step S2: the method for forming the electrode is an evaporation method, a sputtering method or a coating method, and the material of the electrode is conductive material such as gold, silver, copper or aluminum;

the method for forming the electron transport layer and the interface modification layer is evaporation plating, and the electron transport layer is made of fullerene C₆₀Or a derivative thereof, wherein the interface modification layer material is BCP.

9. The method of claim 7, wherein: between steps S1 and S2, further comprising: the surface of the generated perovskite single crystal is cleaned and then is dried in a vacuum drying oven for 1-3h, and the drying temperature is preferably 40-60 ℃.

10. The method of claim 7, wherein: step S1 includes:

s11 preparation of CsBr/CsI and PbBr₂/PbI₂And the RbBr/RbI is dispersed into the solvent to be completely dissolved, and the solution is filtered until the solution is transparent and clear to obtain Cs_(1-x)Rb_xPb(Br_(1-y)I_y)₃Slowly heating the solution in oil bath at 70-145 ℃ until single crystal nucleus is generated, and removing the crystal nucleus;

s12 moving the crystal nucleus into new Cs_(1-x)Rb_xPb(Br_(1-y)I_y)₃In the solution, the crystal is heated in an oil bath and kept at the temperature of 80-135 ℃ for continuous growth until the crystal grows to be a cuboid with the side length of 0.5-1cm, and the all-inorganic perovskite single crystal is prepared.

Technical Field

The invention belongs to the field of X-ray detectors, and particularly relates to an all-inorganic halogen perovskite single crystal X-ray detector and a preparation method thereof.

Background

The X-ray detector has high application value in the fields of medical detection, industrial nondestructive detection, safety inspection and the like. Currently, the commonly used X-ray detectors are classified according to their conversion method of high-energy X-ray photons into charge carriers: one is an indirect type X-ray detector, and the other is a direct type X-ray detector. The indirect X-ray detector converts high-energy radiation into visible light by using a scintillator material, and then detects the visible light by using a traditional photoelectric detector based on a Si material to indirectly obtain a signal related to the radiation, so that the indirect X-ray detector has the advantages of short response time, low detection dose and the like, but the defects of low detector quantum efficiency, poor imaging quality and the like are caused due to light loss and light scattering in the light conversion process of the scintillator material. The direct X-ray detector is prepared based on high atomic number materials such as CdZnTe, amorphous Se and the like, and X-rays can excite electron-hole pairs in the materials to obtain photocurrent, so that signals related to high-energy radiation can be directly detected. Direct X-ray detectors have better imaging quality than indirect X-ray detectors because they do not involve the light conversion process associated with the scintillator material. However, the conventional materials of the direct X-ray detector have the disadvantages of low signal-to-noise ratio, high operating voltage, long signal reading time, and the like. The commercialized X-ray detectors based on these materials are required to be improved in terms of the width of the operating temperature range, the radiation resistance, and the cost reduction.

At present, an X-ray detector based on a halogen perovskite material has shown a good development prospect due to the advantages of good X-ray detection performance, low preparation cost and the like. Among them, organic-inorganic hybrid halogen perovskites (e.g. CH)₃NH₃PbX₃X ═ I, Br, Cl) has a very high carrier mobility lifetime product, a large resistance value, and strong X-ray absorption properties, and has proven to be an extremely promising X-ray radiation detector material. In general, X-ray detectors based on organic-inorganic hybrid perovskites have comparable or better sensitivity than the commercially available Si, α -Se, CZT radiation detectors. However, the following problems still exist in the X-ray detector based on the organic-inorganic hybrid perovskite:

the organic-inorganic hybrid perovskite material has weak bonding force between organic and inorganic components, and is easy to generate structural degradation under the erosion of heat and moisture, so that the stability of the perovskite photoelectric device has serious problems. In addition, the current perovskite photoelectric device mainly comprises a perovskite thin film with a microcrystalline or polycrystalline morphology, and the grain boundary, the gap and the defect existing in the perovskite thin film can cause a current density-voltage curve to have a hysteresis effect, reduce the carrier mobility and improve the recombination probability of carriers, and the factors influence the sensitivity, the performance stability and the service life of an X-ray detector based on the organic-inorganic hybrid perovskite material.

Disclosure of Invention

Technical problem to be solved

In order to solve the above problems in the prior art, the present invention provides an all-inorganic halogen perovskite single crystal X-ray detector, which uses single crystal all-inorganic perovskite to replace microcrystalline or polycrystalline organic-inorganic hybrid perovskite, so as to solve the problem of poor X-ray detection performance and long-term stability in the photoelectric device mainly based on organic-inorganic hybrid perovskite microcrystalline/polycrystalline thin film in the prior art. The invention also relates to a preparation method of the all-inorganic halogen perovskite single crystal X-ray detector.

(II) technical scheme

In order to achieve the purpose, the invention adopts the main technical scheme that:

an all-inorganic halogen perovskite single crystal X-ray detector comprises a perovskite single crystal and electrodes which are oppositely arranged on two sides of the perovskite single crystal, wherein the molecular formula of the perovskite single crystal is Cs_(1-x)Rb_xPb(Br_(1-y)I_y)₃Wherein x is more than or equal to 0 and less than or equal to 0.1, and y is more than or equal to 0 and less than or equal to 0.3.

Wherein, when x is 0, it is expressed as an all-inorganic halogen perovskite single crystal without doping rubidium.

In a preferred embodiment of the present invention, the electrode material is a conductive film of gold, silver, copper or aluminum.

In a preferred embodiment of the present invention, the X-ray detector comprises a perovskite single crystal and electrodes disposed on two sides of the perovskite single crystal, wherein the electrodes are gold or silver plated on two opposite sides of the perovskite single crystal respectively. In this case, the X-ray detector of the present invention is a photoconductive device of electrode/perovskite single crystal/electrode.

In a preferred embodiment of the invention, the X-ray detector comprises a perovskite single crystal, an electron transport layer, an interface modification layer and two electrodes; one side surface of the perovskite single crystal is plated with a conductive film to form an electrode, meanwhile, the other side surface of the perovskite single crystal is sequentially plated with an electron transmission layer and an interface modification layer from inside to outside, and the interface modification layer is further plated with a conductive film to form another electrode. At this time, the X-ray detector of the present invention is a photovoltaic device of an electrode/perovskite single crystal/electrode transmission layer and an interface modification layer/electrode.

In a preferred embodiment of the invention, the thickness of the electrode is 50-150 nm.

In a preferred embodiment of the present invention, the electron transport layer material is fullerene C₆₀Or a derivative thereof, wherein the interface modification layer material is BCP (2, 9-dimethyl-4, 7-biphenyl-1, 10-phenanthroline).

In a preferred embodiment of the present invention, the thickness of the electron transport layer is 20-60nm, and the thickness of the interface modification layer is 6-10nm, preferably 7 nm.

In a preferred embodiment of the invention, the perovskite single crystal has the molecular formula Cs_(1-x)Rb_xPbBr₃Wherein x is more than or equal to 0 and less than 0.1. When x is 0, the perovskite single crystal molecule is CsPbBr₃。

On the other hand, the invention also provides a preparation method of the all-inorganic halogen perovskite single crystal X-ray detector, which comprises the following steps:

s1, preparing all-inorganic halogen perovskite single crystal: growth of CsPbBr by solution method₃Adding soluble salt of rubidium halide into solution of monocrystal to obtain compound with molecular formula of Cs_(1-x)Rb_xPb(Br_(1-y)I_y)₃Wherein x is more than or equal to 0 and less than or equal to 0.1, and y is more than or equal to 0 and less than or equal to 0.3;

s2, preparing a single crystal X-ray detector: and selecting two opposite surfaces of the all-inorganic halogen perovskite single crystal, and respectively manufacturing electrodes on the two opposite surfaces, or manufacturing an electrode on one surface and sequentially forming an electron transmission layer, an interface modification layer and an electrode on the other surface.

When x is 0, the polymer is undoped rubidium, and the amount of rubidium halide added in the solution is 0.

In a preferred embodiment of the present invention, in step S2: the method for forming the electrode is a vacuum evaporation method, and the material of the electrode is gold or silver.

In a preferred embodiment of the present invention, in step S2: the method for forming the electron transport layer and the interface modification layer is vacuum evaporation, and the electron transport layer is made of fullerene C₆₀Or a derivative thereof, wherein the interface modification layer material is BCP.

In a preferred embodiment of the present invention, between steps S1 and S2, the method further comprises: the surface of the generated perovskite single crystal is cleaned and then is dried in a vacuum drying oven for 1-3h, and the drying temperature is preferably 40-60 ℃.

In a preferred embodiment of the present invention, in step S2: two opposite surfaces of the all-inorganic halogen perovskite single crystal are planes with the largest two corresponding upper and lower surfaces of the single crystal.

In a preferred embodiment of the present invention, step S1 includes:

s11 preparation of CsBr/CsI and PbBr₂/PbI₂And the RbBr/RbI is dispersed into the solvent to be completely dissolved, and the solution is filtered until the solution is transparent and clear to obtain Cs_(1-x)Rb_xPb(Br_(1-y)I_y)₃Slowly heating the solution in oil bath at 70-145 ℃ until single crystal nucleus is generated, and removing the crystal nucleus;

s12 moving the crystal nucleus into new Cs_(1-x)Rb_xPb(Br_(1-y)I_y)₃In the solution, the crystal is heated in an oil bath and kept at the temperature of 80-135 ℃ for continuous growth until the crystal grows to be a cuboid with the side length of 0.5-1cm, and the all-inorganic perovskite single crystal is prepared.

The filtering in step S11 is performed by filtering with a PVDF (polyvinylidene fluoride) filter head for 2 or more times.

In step S11, the solvent is DMSO (dimethyl sulfoxide).

New Cs in step S12_(1-x)Rb_xPb(Br_(1-y)I_y)₃The solution is prepared in the same way as in step S11, namely: mixing CsBr/CsI and PbBr₂/PbI₂And the RbBr/RbI is dispersed in the solvent until the RbBr/RbI is completely dissolved, and the solution is filtered until the solution is transparent and clear.

(III) advantageous effects

Compared with the prior art, the technical effects of the scheme of the invention mainly comprise:

(1) compared with organic perovskite, the perovskite single crystal has stronger ionic bond between inorganic and inorganic elements and is more stable theoretically. Therefore, the problems of weak binding force between organic and inorganic components and poor heat resistance and humidity resistance of the traditional organic and inorganic components are solved. The all-inorganic halogen perovskite single crystal has the advantages of more stable structure, stronger moisture-proof and heat-resistant performance, longer service life, simple preparation and lower cost.

(2) Compared with a perovskite material with a microcrystalline morphology or a polycrystalline morphology, the perovskite material adopts the all-inorganic halogen perovskite single crystal, has fewer crystal boundaries, pores and defects in the material, and can improve the sensitivity and the performance stability of the X-ray detector.

Compared with a polycrystalline perovskite thin film, the perovskite single crystal has the advantages of higher carrier mobility, longer carrier life, better stability and the like, so that the prepared X-ray detector has better performance.

(3) The atomic numbers of each main element and the doping element Rb in the material are larger than those of organic elements, so that the material has higher X-ray absorption capacity. At the same time, CsPbBr₃The direct band gap semiconductor has excellent electrical properties of large resistivity, high mu tau value, moderate optical band gap and the like. When a small amount of rubidium is doped, the atomic interaction between Pb and Br/I can be increased, so that the effective transport of electrons and holes is greatly improved, and the detection performance (especially the sensitivity) of the X-ray detector is obviously improved. However, when excess rubidium is doped, for example, when the doping amount molecular ratio of rubidium is 0.1 or more, the sensitivity is rather lowered.

(4) Wherein the electron transport layer is made of fullerene C₆₀Or its derivative, which has strong electron affinity and high electron mobility, and can be used as electron transport layer materialAnd (5) feeding. The interface modification layer material is BCP (2, 9-dimethyl-4, 7-biphenyl-1, 10-phenanthroline), has good electron transport and hole blocking capabilities, and is an ideal interface modification layer material. The structure that both combine together can effectively improve the carrier transmission effect to can effectively improve the performance of X ray detection device.

In summary, the X-ray detector based on the all-inorganic halogen perovskite single crystal material provided by the invention has higher detection performance (performance including response sensitivity, detection stability, durability and the like) than the X-ray detector based on the Si, amorphous Se and CZT materials sold in the market, and has the advantages of simple preparation process, lower cost and good stability.

Drawings

Fig. 1 is a schematic structural diagram of an X-ray detector according to the present invention.

Fig. 2 is a schematic structural diagram of another X-ray detector of the present invention.

FIG. 3 shows the Cs obtained by the preparation_(1-x)Rb_xPbBr₃XRD pattern of perovskite single crystal.

FIG. 4 shows Cs with different Rb doping levels_(1-x)Rb_xPbBr₃Sensitivity test chart of perovskite single crystal X-ray detector.

[ description of reference ]

10 gold/silver electrodes; 20. an all-inorganic perovskite single crystal; 30. an electron transport layer; 40 interface modifying layer.

Detailed Description

For the purpose of better explaining the present invention and to facilitate understanding, the present invention will be described in detail by way of specific embodiments with reference to the accompanying drawings.

The invention mainly provides an X-ray detector based on an all-inorganic halogen perovskite single crystal material, and the molecular formula of the used all-inorganic perovskite single crystal material is Cs_(1-x)Rb_xPb(Br_(1-y)I_y)₃Wherein x is more than or equal to 0 and less than or equal to 0.1, and y is more than or equal to 0 and less than or equal to 0.3. Wherein, when x is 0, it represents all-inorganic perovskite without rubidium doping. And x is more than 0 and less than or equal to 0.1, which means that the doping weight molecular ratio of rubidium is more than 0 and less than 0.1. When y is 0, tableShown as an all inorganic perovskite material without iodine doping.

There are two main types of X-ray detector configurations, as shown in fig. 1-2.

Fig. 1 is an electrode/perovskite single crystal/electrode single-carrier device comprising an electrode 10 of gold or silver material and an all-inorganic perovskite single crystal 20 interposed between the electrodes on both sides. Preferably, the all-inorganic perovskite single crystal 20 has a molecular formula of Cs_(1-x)Rb_xPbBr₃。

Fig. 2 shows an electronic device of an electrode/perovskite single crystal/electrode transmission layer and an interface modification layer/electrode, which comprises a gold/silver electrode 10 formed on the lower side of an all-inorganic perovskite single crystal 20, and an electron transmission layer 30, an interface modification layer 40 and a gold/silver electrode 10 sequentially formed on the upper side of the all-inorganic perovskite single crystal 20. Preferably, the molecular formula of the all-inorganic perovskite single crystal 20 is Cs_(1-x)Rb_xPbBr₃。

The gold/silver electrode 10 is a gold or silver film deposited on two opposite sides (or on the interface modification layer 40) of the all-inorganic perovskite single crystal 20 by vacuum evaporation.

Among them, the electron transport layer 30 is preferably fullerene C₆₀The interface modification layer 40 is preferably BCP, and the electron transport layer 30 and the interface modification layer may be formed on the side surface of the all-inorganic perovskite single crystal 20 by vapor deposition.

Wherein, the thickness of the gold/silver electrode 10 is 50-150nm, the thickness of the electron transmission layer 30 is 20-60nm, and the thickness of the interface modification layer 40 is 6-10nm, preferably 7 nm.

Experiments prove that the pure-inorganic perovskite monocrystal Cs_0.99Rb_0.01PbBr₃The sensitivity of the prepared gold/perovskite single crystal/gold X-ray detector is far superior to that of rubidium-undoped perovskite single crystal CsPbBr₃And a detector.

Expressed as Cs_(1-x)Rb_xPbBr₃(X is more than 0 and less than or equal to 0.1) the preparation method of the all-inorganic perovskite single crystal X-ray detector of the invention is illustrated by way of example, and the corresponding iodine-doped all-inorganic perovskite single crystal can be prepared by adding a small amount of rubidium iodide, or part of cesium bromide or bromine into the solutionThe lead is replaced by cesium iodide or lead iodide.

The X-ray detector can be prepared as follows:

(1) preparation of all-inorganic perovskite single crystals

Mixing the components in a molar ratio of 1-x: x is CsBr, RbBr and PbBr of 1 (x is more than 0 and less than or equal to 0.1)₂Dissolving in DMSO (dimethyl sulfoxide), heating, mixing and stirring for 6-12 hr until the material is completely dissolved, wherein the heating temperature for dissolving and stirring is preferably 40-50 deg.C; filtering the solution twice by using a PVDF (polyvinylidene fluoride) filter head until the solution is transparent and clear to obtain clear Cs_(1-x)Rb_xPbBr₃The solution is heated slowly in an oil bath at 70-115 ℃ until single crystal nuclei are generated, and the crystal nuclei are removed.

Transfer of the resulting nuclei into new clarified Cs_(1-x)Rb_xPbBr₃In the solution, the crystal is heated in an oil bath and kept at the temperature of 80-105 ℃ for continuous growth until the crystal grows to an orange cuboid with the side length of 0.5-1 cm. The new clarified Cs_(1-x)Rb_xPbBr₃The solution is prepared by mixing the components in a molar ratio of 1-x: x is CsBr, RbBr and PbBr of 1 (x is more than 0 and less than or equal to 0.1)₂Dissolving in DMSO (dimethyl sulfoxide), and filtering with PVDF (polyvinylidene fluoride) filter head twice.

The surface of the generated perovskite single crystal is cleaned and then is dried in a vacuum drying oven for 1-3h, and the drying temperature is preferably 40-60 ℃.

(2) X-ray detector for preparing perovskite single crystal

Two planes with the maximum areas corresponding to the upper and lower parts of the single crystal are selected, Au or Ag electrodes are deposited on the two surfaces of the single crystal through a vacuum evaporation method, and the thickness of the electrodes is preferably 70-120 nm.

Or: and depositing an Au or Ag electrode on one surface of the single crystal by a vacuum evaporation method, and sequentially depositing and forming an electron transport layer (C60), an interface modification layer (BCP) and the Au or Ag electrode on the other surface of the single crystal by the vacuum evaporation method. The thickness of the electron transport layer is preferably 20-60nm, and the thickness of the interface modification layer is 6-10nm, preferably 7 nm. The electrode thickness is preferably 50-150 nm.

Above is Cs_(1-x)Rb_xPbBr₃(X is more than 0 and less than or equal to 0.1) as an example to illustrate the preparation process of the X-ray detector; it should be noted that ifWhen part of Br in the perovskite is replaced by I, the growing temperature of the generated single crystal nuclei and the growing temperature of the single crystal are increased in the step (1), and the growing temperature of the generated single crystal nuclei and the growing temperature of the single crystal are increased along with the increase of the iodine-containing ratio, and the growing temperature is increased by 20-40 ℃ correspondingly.

Specific examples of the X-ray detector produced according to the above-described method are given below.