Ionizing radiation conversion device and method for detecting ionizing radiation

Abstract

This ionizing radiation conversion device (100) comprises a first electrode (11), a second electrode (13), and an ionizing radiation conversion layer (12) layered between the first electrode (11) and the second electrode (13). The first electrode (11) contains a first metal, the second electrode (13) contains at least one selected from the group consisting of a second metal and metal oxides, and the ionizing radiation conversion layer (12) contains a perovskite compound. The difference obtained by subtracting the value of the work function of the first electrode (11) from the value of the electron affinity of the ionizing radiation conversion layer (12) is 0-0.4 eV (inclusive).

Description

[Technical field]

[0001] The present disclosure relates to ionizing radiation conversion devices and methods for detecting ionizing radiation. [Background technology]

[0002] There are various devices that can convert ionizing radiation such as X-rays into electrical signals, and by measuring the intensity of ionizing radiation emitted from a material, or by irradiating a material with ionizing radiation and measuring the ionizing radiation that passes through the material, it is possible to obtain internal information about the material. Various materials that convert ionizing radiation into electrical signals have been devised and put to practical use. In general, it is desirable for these materials to contain atoms with large atomic numbers. Currently, amorphous selenium and cesium iodide are used. In recent years, perovskite compounds, such as methylammonium lead iodide, have attracted attention as such materials.

[0003] When ionizing radiation is converted into an electrical signal, the sensitivity can be increased by making the aforementioned materials thicker.

[0004] In Non-Patent Document 1, methylammonium lead iodide is used as a perovskite compound that converts X-rays into electric charges. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Nature Photonics Vol.9, p.444 Summary of the Invention [Problem to be solved by the invention]

[0006] It is an object of the present disclosure to provide an ionizing radiation conversion device that has high sensitivity to ionizing radiation. [Means for solving the problem]

[0007] The ionizing radiation conversion device of the present disclosure comprises: first electrode, A second electrode, and an ionizing radiation conversion layer disposed between the first electrode and the second electrode; Equipped with Where: the first electrode contains a first metal; the second electrode contains at least one selected from the group consisting of a second metal and a metal oxide; The ionizing radiation conversion layer contains a perovskite compound, The difference between the electron affinity of the ionizing radiation conversion layer and the work function of the first electrode is 0 eV or more and 0.4 eV or less. Effect of the Invention

[0008] An object of the present disclosure is to provide an ionizing radiation conversion device that has high sensitivity to ionizing radiation. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 illustrates a cross-sectional view of an ionizing radiation conversion device 100 of the present disclosure. [Diagram 2] FIG. 2 illustrates a cross-sectional view of an ionizing radiation conversion device 200 of the present disclosure. [Diagram 3] FIG. 3 shows an example of the energy band structure of the electrode and the ionizing radiation conversion layer according to the first embodiment. [Figure 4] FIG. 4 shows an example of a cross-sectional energy band structure of the ionizing radiation conversion device according to the first embodiment. [Diagram 5] FIG. 5 shows an example of the energy band structure of the second electrode and the ionizing radiation conversion layer according to the second embodiment. [Figure 6] FIG. 6 shows an example of a cross-sectional energy band structure of an ionizing radiation conversion device according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Findings on which this disclosure is based) In the ionizing radiation conversion layer, in order to convert absorbed ionizing radiation (e.g., X-rays) into electron-hole pairs and to effectively extract the electrons and holes, it is necessary for the ionizing radiation conversion layer and the electrode in contact with it to form an ohmic contact or a contact with a small energy barrier carrier that does not hinder the transport of electrons and holes.

[0011] In order to solve this problem, the present inventors have investigated perovskite compounds as the ionizing radiation conversion material contained in the ionizing radiation conversion layer.

[0012] According to the ionizing radiation conversion device of the present disclosure, contacts can be formed between the ionizing radiation conversion layer and the first and second electrodes with no or small energy barriers, i.e., the ionizing radiation conversion device of the present disclosure has high sensitivity to ionizing radiation and low conversion loss.

[0013] In this disclosure, "ionizing radiation" means alpha rays, beta rays, neutron rays, proton rays, X-rays, or gamma rays.

[0014] (Embodiments of the present disclosure) Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0015] The ionizing radiation conversion device of the present disclosure includes a first electrode, a second electrode, and an ionizing radiation conversion layer disposed between the first electrode and the second electrode. Here, the first electrode contains a first metal. The second electrode contains at least one selected from the group consisting of a second metal and a metal oxide. The ionizing radiation conversion layer contains a perovskite compound. The difference between the electron affinity value of the ionizing radiation conversion layer and the work function value of the first electrode is 0 eV or more and 0.4 eV or less.

[0016] According to the above configuration, the ionizing radiation conversion device of the present disclosure has high sensitivity to ionizing radiation, i.e., the ionizing radiation conversion device of the present disclosure can efficiently convert ionizing radiation into electric charges.

[0017] The ionizing radiation conversion device may be used, for example, as an ionizing radiation detector, an imager, or a dosimeter.

[0018] FIG. 1 illustrates a cross-sectional view of an ionizing radiation conversion device 100 of the present disclosure.

[0019] The ionizing radiation conversion device 100 comprises a first electrode 11, a second electrode 13 and an ionizing radiation conversion layer 12 arranged between the first and second electrodes.

[0020] The ionizing radiation conversion layer 12 contains a perovskite compound.

[0021] In the present disclosure, the term "perovskite compound" refers to an ABX 3 A compound represented by is its analogue.

[0022] ABX 3 The compound represented by the formula: 3 , MgSiO 3 , CsPbI 3 , CsPbBr 3 or (CH 3 NH 3 )PbI 3 It is.

[0023] ABX 3 The analogue of the compound represented by the formula (I) has the following structure (II): do. (i)ABX 3 In the compound represented by the formula: A structure in which a part of the 3 NH 3 ) 3 Bi 2 I 9 ) (ii)ABX 3 In the compound represented by the formula: A structure consisting of materials with different valences (e.g., Cs(Ag 0.5 Bi 0.5 )I 3 )

[0024] The perovskite compound may contain two or more types of cations and one or more types of monovalent anions.

[0025] The perovskite compound may be substantially composed of two or more cations and one or more monovalent anions. "The perovskite compound is substantially composed of two or more cations and one or more monovalent anions" means that the total amount of the two or more cations and one or more monovalent anions is 90 mol% or more with respect to the total amount of all elements constituting the perovskite compound. The perovskite compound may be composed of two or more cations and one or more monovalent anions.

[0026] To increase the sensitivity to ionizing radiation, two or more cations are added, such as Pb 2+ , Sn 2+ , Ge 2+ , and Bi 3+ It may include at least one selected from the group consisting of:

[0027] The monovalent anion is, for example, a halogen anion or a complex anion. Examples of halogen anions are fluorine, chlorine, bromine, or iodine. Examples of complex anions are SCN, - , NO 3 - , or H.C.O.O. - It is.

[0028] Perovskite compounds are, for example, compounds of the formula ABX 3 (A is a monovalent cation and B is and X is a divalent cation and X is a halogen anion.

[0029] The monovalent cation is an organic cation or an alkali metal cation.

[0030] An example of an organic cation is the methylammonium cation (i.e., CH 3 NH 3 + ), Hol Muamidinium cation (i.e., NH 2 CHNH 2 + ), phenylethylammonium Cations (i.e., C 6 H 5 C 2 H 4 NH 3 + ), or guanidinium cations (i.e., CH 6 N 3 + ).

[0031] An example of an alkali metal cation is the cesium cation (i.e., Cs + ) or Rubizi Rb cation (i.e., Rb + ).

[0032] The perovskite compound may contain multiple monovalent cations, for example a mixture of at least one of the organic cations mentioned above and at least one of the metal cations.

[0033] The divalent cation is, for example, a cation of an element of Groups 13 to 15. The divalent cation is, for example, a lead cation (i.e., Pb 2+ ), tin cations (i.e., Sn 2+ ), or germanium cation (i.e., Ge 2+ ) for more efficient conversion of ionizing radiation. 2+ may be also possible.

[0034] Perovskite compounds include, for example, CsPbI 3 or CsPbBr 3 It is.

[0035] To achieve greater sensitivity to ionizing radiation, the perovskite compound may be composed of a monovalent organic cation, a cation of a Group 14 element, and a halogen anion, i.e., the perovskite compound may be an organic-inorganic perovskite compound.

[0036] In order to enhance the sensitivity to ionizing radiation, the organic-inorganic perovskite compound may contain, as an organic cation, at least one selected from the group consisting of a methylammonium cation (hereinafter referred to as "MA") and a formamidinium cation (hereinafter referred to as "FA").

[0037] Cations of group 14 elements are, for example, Pb 2+ or Sn 2+ It is.

[0038] The organic-inorganic perovskite compound is, for example, CH 3 NH 3 PbI 3 , C.H. 3 CH 2 NH 3 PbI 3 , HC(NH 2 ) 2 PbI 3 , or C.H. 3 NH 3 PbBr 3 It is.

[0039] Organic-inorganic perovskite compounds have a high absorption coefficient for ionizing radiation and can efficiently convert ionizing radiation into electric charges. Furthermore, by including organic cations, the recombination of electric charges can be suppressed, allowing electric charges to be extracted efficiently.

[0040] In order to efficiently convert ionizing radiation, the ionizing radiation conversion layer 12 may contain 30 mol % or more of a perovskite compound. The ionizing radiation conversion layer 12 may contain 80 mol % or more of a perovskite compound. The ionizing radiation conversion layer 12 may be made of a perovskite compound.

[0041] In order to convert ionizing radiation efficiently, the ionizing radiation conversion layer 12 may have a thickness of 0.1 μm or more and 1 cm or less. Desirably, the ionizing radiation conversion layer 12 may have a thickness of 100 μm or more and 1 mm or less.

[0042] The first electrode 11 contains a first metal.

[0043] The first metal may be at least one selected from the group consisting of Mg, Zr, Hf, Mn, Cd, Ga, In, and Bi, which can reduce the contact resistance at the interface between the first electrode 11 and the ionizing radiation conversion layer 12.

[0044] The second electrode 13 contains at least one selected from the group consisting of a second metal and a metal oxide.

[0045] The second metal may be at least one selected from the group consisting of Pt and Se. This makes it possible to reduce the contact resistance at the interface between the second electrode 13 and the ionizing radiation conversion layer 12.

[0046] Metal oxides are MoO 3 and W.O. 3 In this case, the contact resistance at the interface between the second electrode 13 and the ionizing radiation conversion layer 12 can be reduced.

[0047] The first electrode 11 may contain 50 mol % or more of the first metal. The first electrode 11 may contain 90 mol % or more of the first metal. Desirably, the first electrode 11 may be made of the first metal.

[0048] The second electrode 13 may contain 50 mol % or more of at least one selected from the group consisting of a second metal and a metal oxide. The second electrode 13 may contain 90 mol % or more of at least one selected from the group consisting of a second metal and a metal oxide. Desirably, the second electrode 13 may be made of at least one selected from the group consisting of a second metal and a metal oxide. The second electrode 13 may be made of the second metal or may be made of a metal oxide.

[0049] FIG. 2 illustrates a cross-sectional view of an ionizing radiation conversion device 200 of the present disclosure.

[0050] The ionizing radiation conversion device 200 includes a charge storage section 14, a thin film transistor 15, and a voltage application section 16 in addition to the components of the ionizing radiation conversion device 100.

[0051] The charge storage portion 14 is electrically connected to the second electrode 13 .

[0052] The thin film transistor 15 is electrically connected to the second electrode 13 and the charge storage portion 14 .

[0053] In the top view of the ionizing radiation conversion device 200 , the first electrode 11 and the ionizing radiation conversion layer 12 are disposed so as to cover almost the entire surface of the thin film transistor 15 .

[0054] Next, an outline of the operation of the direct conversion type ionizing radiation conversion device 200 will be described with reference to FIG. 2. Ionizing radiation emitted from an ionizing radiation generator passes through a subject such as a human body and then enters the ionizing radiation conversion layer 12. In the ionizing radiation conversion layer 12, charges (hole-electron pairs) are excited according to the amount of ionizing radiation (e.g., X-rays) radiated to the perovskite compound. The generated charges move to the second electrode (i.e., pixel electrode) 13 according to the polarity of the voltage applied to the ionizing radiation conversion layer 12 by the voltage application unit 16, and are accumulated in the charge accumulation unit 14 in the thin film transistor 15. Thereafter, the thin film transistor 15 is scanned line-sequentially, so that the charge information accumulated in the charge accumulation unit 14 can be read out from the data bus line. The read-out charge information is converted into a digital image signal and outputted sequentially.

[0055] Ionizing radiation may be detected by detecting charges generated by irradiating the perovskite compound contained in the ionizing radiation conversion layer 12 with ionizing radiation. According to the above detection method, ionizing radiation can be detected with high sensitivity.

[0056] (First embodiment) In a first embodiment, an ionizing radiation conversion layer comprising an organic-inorganic perovskite compound is in contact with a first electrode and a second electrode, where the first electrode and the second electrode have a work function equal to or smaller than the electron affinity of the ionizing radiation conversion layer.

[0057] Fig. 3 shows an example of the energy band structure of the electrode and the ionizing radiation conversion layer according to the first embodiment. Fig. 3 shows the work function (φ1) of the electrode when not in contact with the ionizing radiation conversion layer, and the electron affinity (χ) of the ionizing radiation conversion layer when not in contact with the first electrode and the second electrode. Here, both the first electrode and the second electrode have a work function (φ1) smaller than the electron affinity (χ) of the ionizing radiation conversion layer.

[0058] FIG. 4 shows an example of a cross-sectional energy band structure of the ionizing radiation conversion device according to the first embodiment.

[0059] FIG. 4 is a schematic energy band diagram showing the case where the ionizing radiation conversion layer is in contact with the first electrode and the second electrode.

[0060] From FIG. 4, it can be seen that the ionizing radiation conversion layer has no energy barrier between the first electrode and the second electrode. Therefore, electrons generated in the ionizing radiation conversion layer by ionizing radiation can be effectively extracted. Here, if the energy difference (χ-φ1) between the electron affinity of the ionizing radiation conversion layer and the work function of the first electrode and the second electrode is large, the probability of electron capture at the contact interface increases, and recombination may occur. As a result, electrons are lost.

[0061] If the difference between the electron affinity of the ionizing radiation conversion layer and the work function of the first electrode, and the difference between the electron affinity of the ionizing radiation conversion layer and the work function of the second electrode are both 0 eV or more and 0.4 eV or less, electron capture at the contact interface can be prevented without forming an energy barrier.

[0062] For example, FAPbI is an organic-inorganic perovskite compound that has high sensitivity to ionizing radiation. 3 and MAPbI 3 Examples include:

[0063] FAPbI 3 The electron affinity of is 4.22 eV. The ionizing radiation conversion layer is FAPbI 3 In this case, the first electrode and the second electrode may be made of a material having a work function of 4.22 eV or less. Examples of such materials are Zr, Hf, Mn, Cd, Ga, In, or Bi. The work functions of Zr, Hf, Mn, Cd, Ga, In, and Bi are 4.05 eV, 3.90 eV, 4.10 eV, 4.22 eV, 4.20 eV, 4.12 eV, and 4.22 eV, respectively. The material may be an alloy having a work function of 4.22 eV or less.

[0064] MAPbI 3 The electron affinity of is 3.92 eV. Therefore, the ionizing radiation conversion layer is M APbI 3In this case, the first electrode and the second electrode have a work function of 3.92 eV or less. The material may be made of a material having a work function of 3.92 eV or less. Examples of such materials are Mg or Hf. The work functions of Mg and Hf are 3.66 eV and 3.90 eV, respectively. The material may be an alloy having a work function of 3.92 eV or less.

[0065] As described above, by using a metal or metal oxide having a work function smaller than the electron affinity of the ionizing radiation conversion layer, the contact resistance between the ionizing radiation conversion layer and the electrode can be reduced.

[0066] The first electrode may contain the same metal as the second electrode. This makes the bending of the energy band (i.e., the internal electric field) at both interfaces in Fig. 4 (i.e., the interface between the first electrode and the ionizing radiation conversion layer, and the interface between the second electrode and the ionizing radiation conversion layer) equal. As a result, when a voltage is applied, a constant electric field is applied inside the ionizing radiation conversion layer, and the charges can be accelerated and extracted at a constant rate.

[0067] For example, the first electrode and the second electrode may both contain In. The first electrode and the second electrode may both be made of In.

[0068] Second embodiment In a second embodiment, an ionizing radiation conversion layer comprising an organic-inorganic perovskite compound is in contact with a first electrode and a second electrode, where the second electrode has a work function equal to or greater than the sum of the electron affinity and the forbidden band width of the ionizing radiation conversion layer.

[0069] FIG. 5 shows an example of the energy band structure of the second electrode and the ionizing radiation conversion layer according to the second embodiment.

[0070] 5 shows the electron affinity (χ) and forbidden band width (Eg) of the ionizing radiation conversion layer when not in contact with the second electrode, and the work function (φ2) of the second electrode when not in contact with the ionizing radiation conversion layer, where the second electrode has a work function (φ2) greater than the sum of the electron affinity (χ) and forbidden band width (Eg) of the ionizing radiation conversion layer.

[0071] FIG. 6 shows an example of a cross-sectional energy band structure of an ionizing radiation conversion device according to the second embodiment.

[0072] 6, an energy band diagram of the ionizing radiation conversion layer in contact with the first electrode and the second electrode is shown typically, where the energy difference (χ-φ1) between the electron affinity (χ) of the ionizing radiation conversion layer and the work function (φ1) of the first electrode (i.e., the difference obtained by subtracting the work function of the first electrode from the electron affinity of the ionizing radiation conversion layer) is 0 eV or more and 0.4 eV or less.

[0073] From FIG. 6, it can be seen that there is no energy barrier between the second electrode and the ionizing radiation conversion layer. Therefore, holes generated in the ionizing radiation conversion layer by ionizing radiation can be effectively extracted from the second electrode. Here, if the absolute value of the energy difference ((χ+Eg)-φ2) between the sum of the electron affinity and forbidden band width of the ionizing radiation conversion layer and the work function of the second electrode is large, the probability of trapping holes at the contact interface increases, and recombination may occur. As a result, the holes disappear.

[0074] When the difference obtained by subtracting the work function of the second electrode from the sum of the electron affinity of the ionizing radiation conversion layer and the band gap of the ionizing radiation conversion layer is −0.4 eV or more and 0 eV or less, it is possible to prevent the capture of holes at the contact interface without forming an energy barrier.

[0075] As mentioned above, FAPbI is an organic-inorganic perovskite compound that has high sensitivity to ionizing radiation. 3 and MAPbI 3 Examples include:

[0076] FAPbI 3The sum of the electron affinity and the forbidden band width of is 5.61 eV. FAPbI 3 In the case where the second electrode is made of a material having a work function of 5.61 eV or more, Examples of such materials are Pt or Se. The work functions of Pt and Se are 5.65 eV and 5.90 eV, respectively. The material may be an alloy having a work function of 5.61 eV or more.

[0077] MAPbI 3 The sum of the electron affinity and the forbidden band width of is 5.53 eV. The radiation conversion layer is MAPbI 3 In the case where the second electrode is made of The material may be made of a material having a work function of 5.53 eV or more. Examples of such materials are Pt or Se. The material may be an alloy having a work function of 5.53 eV or more.

[0078] The second electrode may be made of a metal oxide. An example of the metal oxide is WO 3 Ma Or MoO 3 WO 3 and MoO 3 The work functions of are 5.6 eV and 5 .7eV.

[0079] A metal film may be formed on the surface of the second electrode opposite to the surface in contact with the ionizing radiation conversion layer. By using a metal film with high electrical conductivity, a voltage can be applied uniformly in the surface to the ionizing radiation conversion layer. As a result, for example, the resolution of ionizing radiation detection can be improved.

[0080] As described above, by using a metal or metal oxide having a work function larger than the sum of the electron affinity and forbidden band width of the ionizing radiation conversion layer as the material of the second electrode, the contact resistance between the ionizing radiation conversion layer and the second electrode can be reduced.

[0081] The electron affinity or the energy level of the conduction band of the ionizing radiation conversion film can be measured by inverse photoelectron spectroscopy. It can also be determined from the sum of the energy level of the upper end of the valence band and the forbidden band width measured from the optical transmission spectrum or photoluminescence. The energy level of the upper end of the valence band, which is the sum of the electron affinity and the forbidden band width of the ionizing radiation conversion film, can be measured by the XPS method (X-ray photoelectron spectroscopy), the UPS method (ultraviolet photoelectron spectroscopy), or the PYS method (photoelectron. yield spectroscopy).

[0082] The work function of the electrode can be measured similarly by the XPS method, the UPS method, or Auger electron spectroscopy.

[0083] (Method of detecting ionizing radiation) The method for detecting ionizing radiation according to the present disclosure is a method for detecting ionizing radiation using the ionizing radiation conversion device according to the present disclosure described above.

[0084] That is, the method for detecting ionizing radiation according to the present disclosure includes, for example, first electrode, A second electrode, and an ionizing radiation conversion layer disposed between the first electrode and the second electrode; Equipped with Where: the first electrode contains a first metal; the second electrode contains at least one selected from the group consisting of a second metal and a metal oxide; The ionizing radiation conversion layer contains a perovskite compound, and a difference between the electron affinity of the ionizing radiation conversion layer and the work function of the first electrode is 0 eV or more and 0.4 eV or less; In the ionizing radiation detection method of the present disclosure, an ionizing radiation conversion device is used to detect charges generated by irradiating the perovskite compound with ionizing radiation.

[0085] (Method of manufacturing an ionizing radiation conversion device) An example of a method for manufacturing an ionizing radiation conversion device will now be described with reference to FIG.

[0086] First, the second electrode 13 is formed on a substrate (not shown). The substrate may be made of, for example, glass or silicon. A layer made of, for example, In is formed as the second electrode 13 on the substrate by a sputtering method. The film thickness of the second electrode 13 is, for example, 500 nm.

[0087] Next, the ionizing radiation conversion layer 12 is formed on the second electrode 13 .

[0088] A seed layer of the ionizing radiation conversion layer is formed on the second electrode 13 by a spin coating method. The seed layer is, for example, methylammonium iodide (i.e., CH 3 NH 3 I) and PbI 2 A dimethyl sulfoxide solution containing each of these was rotated at 3000 rpm on the second electrode 13. By pin-coating, CH 3 NH 3 PbI 3 The thickness of the seed layer can be, for example, , 300 nm.

[0089] Next, the substrate on which the seed layer was formed was immersed in supersaturated CH 3 NH 3 I and PbI 2 Including γ- By immersing in a butyrolactone solution, 3 NH 3 PbI 3 The layer grows as a crystal. This forms the ionizing radiation conversion layer 12. The ionizing radiation conversion layer 12 has a thickness of, for example, 300 μm.

[0090] Finally, the first electrode 11 is formed on the ionizing radiation conversion layer 12. A layer made of, for example, In is formed by sputtering on the ionizing radiation conversion layer 12. The film thickness of the first electrode 11 is, for example, 500 nm.

[0091] In this manner, an ionizing radiation conversion device is obtained. [Industrial Applicability]

[0092] The ionizing radiation conversion device of the present disclosure is utilized, for example, in an ionizing radiation detector. [Explanation of symbols]

[0093] 11 1st electrode 12 Ionizing radiation conversion layer 13 Second electrode 14 Charge storage section 15 Thin-film transistor 16 Voltage application section 100, 200 Ionizing radiation conversion device

Claims

1. a first electrode; A second electrode, and an ionizing radiation conversion layer disposed between the first electrode and the second electrode; Equipped with Where: The first electrode contains a first metal; the second electrode contains at least one selected from the group consisting of a second metal and a metal oxide; The ionizing radiation conversion layer contains a perovskite compound, a difference between the electron affinity of the ionizing radiation conversion layer and the work function of the first electrode is 0 eV or more and 0.4 eV or less; Ionizing radiation conversion device.

2. a difference between the electron affinity of the ionizing radiation conversion layer and the work function of the second electrode is 0 eV or more and 0.4 eV or less; 10. The ionizing radiation conversion device of claim 1.

3. a difference obtained by subtracting a work function value of the second electrode from a sum of an electron affinity value of the ionizing radiation conversion layer and a forbidden band width value of the ionizing radiation conversion layer is −0.4 eV or more and 0 eV or less; 10. The ionizing radiation conversion device of claim 1.

4. 4. The ionizing radiation conversion device according to claim 1, wherein the perovskite compound comprises two or more types of cations and one or more types of anions.

5. The two or more cations are Pb 2+ , Sn 2+ , Ge 2+ , and Bi 3+ At least one selected from the group consisting of:

5. An ionizing radiation conversion device according to claim 4.

6. The first metal is at least one selected from the group consisting of Mg, Zr, Hf, Mn, Cd, Ga, In, and Bi; An ionizing radiation conversion device according to any one of claims 1 to 5.

7. The second metal is at least one selected from the group consisting of Pt and Se; An ionizing radiation conversion device according to any one of claims 1 to 6.

8. The metal oxide is MoO 3 and W.O. 3 At least one selected from the group consisting of: An ionizing radiation conversion device according to any one of claims 1 to 7.

9. The first electrode contains the same metal as the second electrode. An ionizing radiation conversion device according to any one of claims 1 to 6.

10. the ionizing radiation conversion layer is in contact with the first electrode and the second electrode; An ionizing radiation conversion device according to any one of claims 1 to 9.

11. a first electrode; A second electrode, and an ionizing radiation conversion layer disposed between the first electrode and the second electrode; Equipped with Where: The first electrode contains a first metal; the second electrode contains at least one selected from the group consisting of a second metal and a metal oxide; The ionizing radiation conversion layer contains a perovskite compound, and a difference between the electron affinity of the ionizing radiation conversion layer and the work function of the first electrode is 0 eV or more and 0.4 eV or less; an ionizing radiation conversion device; detecting charges generated by irradiating the perovskite compound with ionizing radiation using the ionizing radiation conversion device; Methods for detecting ionizing radiation.

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