Core-shell particles, complexes, light-receiving components for photoelectric conversion elements, and photoelectric conversion elements

Abstract

The core-shell particle (10) has an inorganic nanoparticle (11) with the ability to convert light wavelengths and a capping layer (12) formed on the surface of the inorganic nanoparticle (11) and made of an inorganic perovskite-type material. The core-shell particle (10) has a core-shell structure.

Description

TECHNICAL FIELD

[0001] The present application relates to a core-shell particle, a composite, a light-receiving member for a photoelectric conversion element, and a photoelectric conversion element. This application claims priority from Japanese Patent Application No. 2020-093726 filed on May 28, 2020, the content of which is incorporated herein by reference. BACKGROUND

[0002] Photoelectric conversion elements such as solar cells and photodiodes are widely used in various fields. However, conventional photoelectric conversion elements have a problem that the detection sensitivity to light in the near-infrared region is weaker than that to light in the visible region. If the detection sensitivity to light in the near-infrared region can also be improved as in the case of visible light, for example, the photoelectric conversion efficiency can be improved in solar cells.

[0003] In Patent Literature 1, a technology is disclosed in which up-conversion nanoparticles are used as inorganic porous bodies for supporting an organic-inorganic composite perovskite compound (which serves as a power generation layer). Here, the so-called up-conversion nanoparticles refer to particles having a particle size of nm order that have a function of converting long-wavelength light such as infrared light into short-wavelength light such as visible light and ultraviolet light. This technology converts long-wavelength light such as near-infrared light absorbed by inorganic core-shell particles into short-wavelength light such as visible light and ultraviolet light, and causes it to be reabsorbed in an organic-inorganic composite perovskite crystal, thereby exciting energy and generating electromotive force.

[0004] In Non-Patent Literature 1, a technology is disclosed in which the up-conversion function of inorganic nanoparticles (Lanthanide-doped NPS) is utilized in a state in which the inorganic nanoparticles and inorganic perovskite quantum dots (CaPbX3(X = Cl, Br, I) PeQDs) are mixed apart from each other. This technology causes visible light generated by the inorganic nanoparticles by near-infrared light excitation to be reabsorbed by the inorganic perovskite quantum dots to emit light.

[0005] Prior Art Documents

[0006] Patent Literature

[0007] Patent Literature 1: Japanese Patent Application Publication No. 2015-92563

[0008] Non-Patent Literature

[0009] Non-Patent Literature 1: Wei Zhen et al., Nature Communications (2018) 9: 3462 SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] With the constitution disclosed in the above-described document, energy loss at the time of reabsorption of the light after wavelength conversion by the perovskite cannot be avoided, and thus in the case where the absorbed light is weak, it is difficult to generate sufficient electromotive force, light emission.

[0012] With the conventional up-conversion nanoparticles containing rare earth ions, the concentration of the ions responsible for light emission needs to be 1 to 5%, and when the concentration of the ions responsible for light emission is high, light emission is quenched. The reason for this is that under high concentration conditions, cross relaxation occurs between light emitting substances, and energy is deactivated due to thermal vibration of the chain-like organic molecules covering the surface of the nanoparticles. Thus, the amount of light absorption is very small, and unless strong light, up-conversion does not occur.

[0013] The present application was made in view of the above-described circumstances, and the object of the present application is to be able to use long-wavelength weak light to obtain high visible light sensitization properties.

[0014] Means for solving the problem

[0015] To solve the above-described problem, the present application provides a core-shell particle, a composite, a light-receiving member for a photoelectric conversion element, and a photoelectric conversion element. Furthermore, the present application employs the following means.

[0016] (1) One embodiment of the present application relates to a core-shell particle including: an inorganic nanoparticle having a wavelength conversion ability of light; and a covering layer formed on the surface of the inorganic nanoparticle and formed of an inorganic perovskite-type substance, the core-shell particle having a core-shell structure.

[0017] (2) In the core-shell particle according to the above-described (1), the inorganic nanoparticle preferably contains a rare earth element.

[0018] (3) One embodiment of the present application relates to a composite including a perovskite structure as a main component, and further including a core-shell particle according to any one of the above-described (1) or (2).

[0019] (4) One embodiment of the present application relates to a light-receiving member for a photoelectric conversion element in which a layer formed of the composite according to the above-described (3) and a layer formed of an aggregate or a film including an organic or inorganic semiconductor (including a metal complex) as a main component are stacked.

[0020] (5) One embodiment of the present application relates to a photoelectric conversion element including the light-receiving member for a photoelectric conversion element according to the above-described (4) between a hole-transporting layer and an electron-transporting layer.

[0021] (6) In one aspect of the present invention, the photoelectric conversion element is formed by sequentially stacking the following first layer, second layer and third layer, wherein the first layer is composed of a plurality of particles or aggregates or thin films containing inorganic semiconductors as the main component, the second layer is formed on the surface of the first layer and is composed of the composite as described in claim 3, and the third layer is composed of a plurality of particles or aggregates or thin films containing organic or inorganic semiconductors (including metal complexes) as the main component, wherein in the conduction band, the energy level of the second layer is higher than the energy level of the first layer, and the energy level of the third layer is higher than the energy level of the second layer.

[0022] (7) Regarding the photoelectric conversion element described in (6) above, the third layer contains an organometallic complex as the main component, and the energy level of the second layer in the valence band can be higher than the energy level of the third layer.

[0023] The effects of the invention

[0024] According to the present invention, by forming a perovskite capping layer on the surface, the doping concentration of the luminescent material, which was previously only a few percent, can be increased to 100%. This allows for the use of weak light at long wavelengths to obtain high visible light sensitization characteristics.

[0025] According to the present invention, it is possible to provide a light-receiving component and a photoelectric conversion element for core-shell particles, composites, photoelectric conversion elements and which can obtain high visible light sensitization characteristics using weak light of long wavelengths. Attached Figure Description

[0026] [ Figure 1 [This is a cross-sectional view of a core-shell particle according to one embodiment of the present invention.]

[0027] [ Figure 2 To have Figure 1 A cross-sectional view of a photoelectric conversion element of a core-shell particle.

[0028] [ Figure 3 [Showing] Figure 2 The structure of the energy bands of each layer during the operation of the photoelectric conversion element.

[0029] [ Figure 4 To have Figure 1 A cross-sectional view of a modified example of a photoelectric conversion element of a core-shell particle.

[0030] [ Figure 5 [Showing] Figure 4 The structure of the energy bands of each layer during the operation of the photoelectric conversion element.

[0031] [ Figure 6 ]for Figure 2 A cross-sectional view of the object being processed during the manufacturing process of a photoelectric conversion element.

[0032] [ Figure 7 [Image showing the emission spectra of core-shell particles 1 and 2 and nanoparticle 1.]

[0033] [ Figure 8 [This is a graph showing the variation in absorption rate caused by the different structures of the core-shell particles in the second layer.]

[0034] [ Figure 9 [This is a SEM image of a cross-section of the photoelectric conversion element manufactured as Example 2.]

[0035] [ Figure 10 [A diagram showing the emission spectrum produced after absorbing light whose wavelength has been converted by the second layer of the photoelectric conversion element of Example 2.]

[0036] [ Figure 11 [A graph showing the response speed of the photocurrent obtained in the photoelectric conversion element.] Detailed Implementation

[0037] Hereinafter, the core-shell particles, composites, light-receiving components for photoelectric conversion elements, and photoelectric conversion elements according to embodiments of the present invention will be described in detail using the accompanying drawings. It should be noted that in the drawings used in the following description, for ease of understanding and convenience, some characteristic parts are sometimes shown enlarged, and the dimensions and proportions of each component may not be the same as in reality. Furthermore, the materials, dimensions, etc., exemplified in the following description are merely examples, and the present invention is not limited thereto; appropriate modifications can be made within the scope of its spirit and intent.

[0038] (Nuclear-shell particle)

[0039] Figure 1 A cross-sectional view illustrating the structure of a core-shell particle 10 according to an embodiment of the present invention is shown. The core-shell particle 10 mainly comprises inorganic nanoparticles 11 and a covering layer 12 thereof, and has a core-shell structure.

[0040] The inorganic nanoparticles 11 are particles with a particle size (diameter) 11a ranging from 10 nm to 100 nm, and possess the ability to convert light wavelengths. Here, the ability to convert light wavelengths refers to the ability to convert the wavelength of incident light and emit light of a different wavelength. In this embodiment, an example will be given of the case where the wavelength of incident near-infrared light is converted into visible light and emitted.

[0041] As the main material for inorganic nanoparticles 11, examples include materials containing at least one of rare earth elements such as erbium (Er), thulium (Tm), ytterbium (Yb), neodymium (Nd), holmium (Ho), praseodymium (Pr), gadolinium (Gd), europium (Eu), terbium (Tb), samarium (Sm), and cerium (Ce), or compounds thereof.

[0042] The capping layer 12 is formed on the surface of the inorganic nanoparticles 11 and is made of an inorganic perovskite-type material. Since the surface of typical rare-earth element upconversion nanoparticles is covered by multiple chain-like organic molecules (oleylamine, oleic acid, etc.), luminescence dissipation occurs due to the thermal vibration of these chain-like organic molecules. On the other hand, the capping layer 12 of the core-shell particles 10 of this disclosure covers the surface of the inorganic nanoparticles 11, thus avoiding the thermal vibration of the chain-like organic molecules present in typical upconversion nanoparticles, and suppressing luminescence dissipation caused by thermal vibration. The coverage of the inorganic nanoparticles 11 by the capping layer 12 should be approximately 50% or more, and 100% is preferred.

[0043] The thickness 12a of the capping layer 12 can be at least 5% of the particle size 11a of the inorganic nanoparticles, and preferably it is approximately uniform across the entire surface of the inorganic nanoparticles. The thicker the capping layer 12a, the higher the photoelectric conversion efficiency.

[0044] As materials constituting the capping layer 12, inorganic perovskite-type materials can include complexes formed of three inorganic elements, such as CsPbX3 (X = Cl). - ,Br - I - X contains at least one of the halide ions. For example, when using ErYF4 or Er,Yb-doped NaYF4 (NaYF4:Er,Yb) as inorganic nanoparticles 11, the photoelectric conversion efficiency is improved if CsPbBr3 or CsPbI3 is used, which is therefore preferred. When using Tm,Yb-doped NaYF4 (NaYF4:Tm,Yb), the photoelectric conversion efficiency is improved if CsPbCl3 is used, which is therefore preferred.

[0045] Figure 1 (b) indicates Figure 1 A modified example of the core-shell particle 10 shown in (a). The capping layer 12 can be as follows: Figure 1 As shown in (b), it can be formed by stacking two layers, or it can be formed by stacking three or more layers.

[0046] (Photoelectric conversion element)

[0047] Figure 2 (a) is a cross-sectional view of a photoelectric conversion element 100 having core-shell particles 10. The photoelectric conversion element 100 is mainly composed of a positive electrode layer (positive electrode component) 101, a negative electrode layer (negative electrode component) 102, and a photoelectric conversion layer 103 sandwiched between them.

[0048] A buffer layer 107 may be sandwiched between the negative electrode layer 102 and the photoelectric conversion layer 103, wherein the buffer layer 107 has a position at Ec2 With E c3 (E c2 and E c3 E (as the conduction band energy level between the negative electrode layer 102 and the photoelectric conversion layer 103) cb As the conduction band energy level (i.e., becoming E) c2 <E cb <E c3 Examples of materials that can be used to form the buffer layer 107 include europium oxide (Eu2O3), titanium oxide, and tin oxide.

[0049] In order to capture light in the photoelectric conversion layer 103, the negative electrode layer 102 is preferably made of a light-transmitting material, such as antimony-doped indium oxide (ATO), indium tin oxide (ITO), zinc oxide, tin oxide, fluorine-doped indium oxide (FTO), etc. In the manufacturing process of the photoelectric conversion layer 103 of this embodiment, heat treatment is required; therefore, among these materials, heat-resistant ATO is preferred as the material for the negative electrode layer 102.

[0050] The positive electrode layer 101 can be opaque. As the electrode material, metals, conductive polymers, etc., can be used. Specific examples of electrode materials include metals such as gold (Au), silver (Ag), aluminum (Al), and zinc (Zn), as well as alloys of two or more of these metals, graphite, graphite intercalation compounds, polyaniline and its derivatives, and polythiophene and its derivatives. As a transparent material for the positive electrode layer 101, ITO can be used.

[0051] like Figure 2As shown in (a), the photoelectric conversion layer 103 preferably comprises a first layer 104a mainly composed of a plurality of particles (hereinafter sometimes referred to as "particles of inorganic semiconductors") 20 containing inorganic semiconductors as the main component, and a second layer 105 and a third layer 106 are stacked thereon. The second layer 105 is formed on the surface of the first layer 104a and is composed of a condensed mass or thin film (composite) containing perovskite structures as the main component and also containing core-shell particles 10. The third layer 106 is composed of a plurality of particles or their condensed mass or thin film containing organic or inorganic semiconductors (including metal complexes) as the main component. That is, the photoelectric conversion element 100 is preferably configured in such a way that it is arranged in the order of positive electrode layer 101, third layer 106, second layer 105, first layer 104, and negative electrode layer 102, forming at least a current path from the positive electrode layer 101 to the negative electrode layer 102. Here, "containing inorganic semiconductors as a main component" means that the inorganic semiconductor particles 20 contain an amount of inorganic semiconductors in order to perform the functions of the present invention. Specifically, for example, the content of inorganic semiconductors exceeds 50% by volume. Preferably, it exceeds 90% by volume, and more preferably, it can be substantially composed of inorganic semiconductors. "Containing perovskite structures as a main component" means that, relative to the total mass of the second layer 105, the perovskite structures contain an amount in order to perform the functions of the present invention. Specifically, for example, the content of perovskite structures exceeds 50% by volume. Preferably, it is 70% by volume or more. Furthermore, "containing organic or inorganic semiconductors (including metal complexes) as a main component" means that, relative to the total mass of the third layer 106, the aggregates or thin films (complexes) containing core-shell particles 10 contain an amount in order to perform the functions of the present invention. Specifically, for example, the content of aggregates or thin films (complexes) containing core-shell particles 10 exceeds 50% by mass. Preferably, it exceeds 90% by volume, and more preferably, it can be substantially composed of organic or inorganic semiconductors (including metal complexes). The more current paths formed, the better. Adjacent current paths may or may not be electrically connected to each other. It should be noted that in this embodiment, "layer" refers to a film formed through one or more film-forming processes, and is not limited to a flat layer. In addition, it may not be a single piece.

[0052] Furthermore, the material composition of the three layers 104 to 106 is determined as follows: the energy levels of the conduction band (LUMO, excited state) increase in the order of the first layer 104, the second layer 105, and the third layer 106. For example, regarding the first layer 104, the valence band energy level can be -8 eV or higher, and the conduction band energy level can be -4 eV or lower. In this case, regarding the second layer 105, the valence band energy level can be -6.0 eV or higher, and the conduction band energy level can be -3 eV or lower. Additionally, regarding the third layer 106, it is preferable that the conduction band energy level is -2 eV or lower.

[0053] The first layer 104a is an aggregate of multiple inorganic semiconductor particles 20 formed on the negative electrode layer 102, and is a porous film with multiple gaps between the inorganic semiconductor particles 20. The inorganic semiconductor particles 20 connected to the second layer 105 are in direct contact with the negative electrode layer 102 in a manner that is electrically connected to it, or are indirect contact with the negative electrode layer 102 through other inorganic semiconductor particles 20.

[0054] The inorganic semiconductor included in the particle 20, which is an inorganic semiconductor, is preferably an inorganic semiconductor whose absorption wavelength is in the ultraviolet region, such as titanium oxide and zinc oxide. The thickness of the first layer 104 is preferably about 10 nm to 1000 nm, and more preferably about 50 nm to 500 nm.

[0055] The second layer 105 is a thin film that covers the exposed portion of the surface of the inorganic semiconductor particles 20 during its manufacturing stage, i.e., the portion that is not in contact with either the negative electrode layer 102 or the inorganic semiconductor particles 20. The second layer 105 does not need to cover the entire exposed portion, but in order to form the aforementioned current path, it must at least cover the positive electrode layer 101 side.

[0056] The perovskite structure constituting the second layer 105 consists of Pb 2+ Sn 2+ Metal cations, I - Cl - Halogen anions such as Br-, CH3NH3 + (MA), NH=CHNH2 + (FA), C s + It is composed of multiple molecules of organic cations. The size and shape of the band gap can be changed by selecting the number of ions from each of the metal cations, halide anions, and organic cations. Adding tin to the perovskite structure narrows the band gap and improves the responsiveness to long-wavelength light such as near-infrared light, but it is easily oxidized in the atmosphere, resulting in deterioration of properties. In the molecules constituting the perovskite structure, halide anions are arranged at the vertices of a regular octahedron centered on the metal ion, and organic cations are arranged near a cube containing regular octahedrons centered on the metal ion. Specifically, it forms a structure in which regular octahedrons formed by metal ions and halide anions form a three-dimensional grid, and organic cations enter the interstices.

[0057] As the core-shell particles 10 form the second layer 105 upon contact with the perovskite structure, the boundary between the capping layer 12 in the core-shell particles 10 and the perovskite structure disappears. Therefore, light converted into visible light by the core-shell particles 10 is efficiently absorbed by the perovskite structure containing the capping layer 12. This improves the light detection sensitivity of the photoelectric conversion element 100 in the near-infrared region.

[0058] When the core-shell particles 10 in the second layer 105 are 5 wt% or more, the sensitivity to light in the near-infrared region is improved, which is therefore preferred. When the core-shell particles 10 in the second layer 105 exceed 30 wt%, it is difficult to form a perovskite structure, which is therefore preferred to be 30 wt% or less.

[0059] Furthermore, it is preferable that the valence band energy level of the second layer 105 is lower than that of the third layer 106, and that it is discontinuously connected to the same energy level. Examples of compositions for the second layer 105 (perovskite structure) that satisfy the above conditions include CH3NH3Pb13, NH=CHNH2PbI3, and CsPbI3. In addition, substances obtained by changing the composition ratio of I to Cl or Br in the halide anion can also be cited.

[0060] The third layer 106 is preferably a thin film covering the surface (exposed surface) of the perovskite structure contained in the second layer in the photoelectric conversion element precursor composed of the first layer 104 and the second layer 105. The third layer 106 is formed of any one of p-type organic semiconductors, inorganic semiconductors, and organometallic complexes. Figure 2 In (a), an example of an organometallic complex is shown. Figure 2 In (a), 106A represents the inorganic transition metal ion of the third layer 106, and 106B represents the organic ligand of the third layer 106. The thickness of the third layer 106 is preferably, for example, 1 nm or more and 100 nm or less.

[0061] Examples of p-type organic semiconductors constituting the third layer include copper bath (BCP), 2,2',7,7'-tetra(N,N'-di-p-methoxyaniline)-9,9'-spirodifluorene (Spiro-OMeTAD), poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS), and N,N,N',N'-tetra(4-methoxyphenyl)benzidine (TPD).

[0062] Examples of p-type inorganic semiconductors that constitute the third layer include CuI and CuSCN.

[0063] It should be noted that when the photoelectric conversion element 100 of this embodiment is applied to a photosensitive sensor or a photoelectric power generation element (solar cell), the photoelectric conversion element 100 is mounted on a semiconductor substrate such as silicon or a glass substrate. In this case, for example, the following device configuration can be described: (1) A transparent positive electrode layer 101 is formed on the uppermost layer that is furthest from the aforementioned semiconductor substrate (i.e., a configuration in which the layers are stacked in the order of (transparent) positive electrode layer 101 / third layer 106 / second layer 105 / first layer 104 / negative electrode layer 102 / (Si) substrate from the uppermost layer on the light-incident side).

[0064] (2) The transparent negative electrode layer 102 is formed in a manner adjacent to the glass substrate (i.e., it is constructed by stacking the (glass) substrate / negative electrode layer 102 / first layer 104 / second layer 105 / third layer 106 / positive electrode layer 101 in the order of light incident side).

[0065] (3) The transparent negative electrode layer 102 is formed in the uppermost layer that is furthest from the semiconductor substrate (i.e., it is a configuration in which the (transparent) negative electrode layer 102 / first layer 104 / second layer 105 / third layer 106 / positive electrode layer 101 / (Si) substrate are stacked from the uppermost layer on the light-incident side).

[0066] (Band structure)

[0067] Figure 3 (a) to (c) show the structure of the energy bands of each layer during the operation of the photoelectric conversion element 100 according to this embodiment.

[0068] In the absence of illumination, the conduction band energy level of the third layer 106 is higher than the Fermi level of the positive electrode layer 101 on the positive electrode layer side, such as... Figure 3 As shown in (a), the current from the positive electrode layer 101 toward the negative electrode layer 102 is blocked.

[0069] When light with a wavelength greater than 800 nm shines on the photoelectric conversion element, the core (inorganic nanoparticles 11) of the core-shell particles 10 constituting the second layer 105 absorbs the light and converts the wavelength into visible light. The perovskite structure absorbs the wavelength-converted light ( Figure 3 (b) It should be noted that, Figure 3 In (b), the dashed and solid arrows of the core-shell particle 10 represent the same energy level. Through light absorption, the perovskite structure generates electrons (e) and holes (h), with the electrons (e) moving to the conduction band (E). c1 Hole h moves to valence band E v3 ( Figure 3 (c)).

[0070] The above example illustrates the case where the first layer, 104a, is a porous membrane, but it can also be illustrated as follows: Figure 2 In this way, the first layer 104b of (b) is formed into a uniform film.

[0071] (Example of a modified photoelectric conversion element)

[0072] Next, variations of the photoelectric conversion element will be described. Hereinafter, similar components will be distinguished by different letters following the same designation. Descriptions of the same component will be omitted. Furthermore, if a component has substantially the same functional configuration as a similar component described herein, the description of that component will be omitted.

[0073] Figure 4 (a) is a cross-sectional view of a photoelectric conversion element 100b having core-shell particles 10. The photoelectric conversion element 100b mainly consists of a positive electrode layer (positive electrode component) 101, a negative electrode layer (negative electrode component) 102, and a photoelectric conversion layer 103b sandwiched between them. It should be noted that... Figure 4 (a) is a cross-sectional view showing the detailed structure, but depending on the situation, sometimes it may also be as shown in the diagram. Figure 4 (b) is recorded in this simple way. Incidentally, Figure 4 In (b), in the configuration of the photoelectric conversion layer 103c, the second layer 105c and the third layer 106c are shown as layers opposite to the negative electrode layer 102 (and the buffer layer 107) and the positive electrode layer 101c. Figure 4 The photoelectric conversion layer 103c of (b) is Figure 4 A simplified description of the photoelectric conversion layer 103b in (a). In this case, Figure 4 The first layer 104a of (a) corresponds to Figure 4 (b) of 104c, Figure 4 The second layer 105 of (a) corresponds to Figure 4 (b) of 105c. Figure 4 The third layer 106b of (a) corresponds to Figure 4 The third layer of (b) is 106c.

[0074] (Photoelectric conversion layer)

[0075] like Figure 5As shown in (a), the photoelectric conversion layer 103b mainly comprises a first layer 104a consisting of a plurality of particles (i.e., particles of inorganic semiconductors) 20 or their aggregates or thin films containing inorganic semiconductors as the main component, and a second layer 105 and a third layer 106b are stacked thereon. The second layer 105 is formed on the surface of the first layer 104a and consists of an aggregate or thin film (composite) containing perovskite structures as the main component and also containing core-shell particles 10. The third layer 106b consists of a plurality of particles or their aggregates or thin films containing organometallic complexes as the main component. Here, "containing organometallic complexes as the main component" means that the content of organometallic complexes in the particles or their aggregates or thin films exceeds 50% by volume. Preferably, it exceeds 90% by volume, and more preferably, it can be substantially composed of inorganic semiconductors. That is, the photoelectric conversion layer 103b is preferably configured in the following manner: arranged in the order of positive electrode layer 101, third layer 106b, second layer 105, first layer 104, and negative electrode layer 102, forming at least a current path from positive electrode layer 101 to negative electrode layer 102. The more current paths formed, the better. Adjacent current paths may or may not be electrically connected to each other.

[0076] Furthermore, the material composition of the three layers 104 to 106b is determined as follows: the energy levels of the conduction band (LUMO, excited state) increase in the order of the first layer 104, the second layer 105, and the third layer 106b, with the energy level of the valence band (HOMO, ground state) of the second layer being higher than that of the valence band of the third layer 106b. Within the conduction band, the energy level of the second layer 105 is higher than that of the first layer 104, and the energy level of the third layer 106b is higher than that of the second layer 105. For example, regarding the first layer 104, the valence band energy level can be -8 eV or higher, and the conduction band energy level can be -4 eV or lower. In this case, regarding the second layer 105, the valence band energy level can be -5.5 eV or higher, and the conduction band energy level can be -3 eV or lower. Furthermore, regarding the third layer 106b, it is preferable that the valence band energy level is -6 eV or higher, and the conduction band energy level is -2 eV or lower.

[0077] The third layer 106b is preferably a thin film covering the surface (exposed surface) of the molecules of the perovskite structure contained in the second layer of the photoelectric conversion element precursor composed of the first layer 104 and the second layer 105. The molecules of the organometallic complex constituting the third layer 106b are obtained by coordinating and bonding an inorganic transition metal with an organic ligand. Here, 106A represents the inorganic transition metal ion of the third layer 106b, and 106B represents the organic ligand of the third layer 106b.

[0078] In the organometallic complex, inorganic transition metal ions are preferably present locally in a film-like manner on the second layer side, directly bonded to the perovskite structure of the second layer 105. Conversely, organic ligands are preferably present locally in a film-like manner on the side opposite to the second layer (the positive electrode side). Furthermore, to achieve photocurrent amplification as described later, it is preferable that the molecules of the organometallic complex are bonded to the molecules of the perovskite structure in a current path from the positive electrode layer 101 side to the second layer 105 side, arranged in the order of organic ligands and inorganic transition metal ions. That is, it can be divided into a layer formed by inorganic transition metal ions and a layer formed by organic ligand ions. It should be noted that the boundary between the two layers can be confirmed, for example, using a transmission electron microscope (TEM).

[0079] As inorganic transition metal ions, Eu, for example, whose reduction energy level is LUMO, can be cited. 3+ Cr 3+ The oxidation energy level becomes the Ru of HOMO. 2+ Fe 2+ Mn 2+ Co 2+ Furthermore, examples of organic ligands include ligands of common metal complexes, such as (i) organic compounds having carboxyl, nitro, sulfonic acid, phosphate, hydroxyl, oxo, and amino groups; (ii) ethylenediamine derivatives; (iii) organic ligands containing heterocyclic atoms, such as terpyridine derivatives, phenanthroline derivatives, and bipyridine derivatives; and (iv) acetylacetone-based organic ligands, such as catechol derivatives, quinone derivatives, naphtholic acid derivatives, and acetylacetone derivatives (specifically, acetylacetone). (Here, "acetylacetone-based organic ligands" refers to organic ligands that can coordinate with multiple transition metal ions (e.g., forming a six-membered ring) through two oxygen atoms.) It should be noted that terpyridine derivatives are substances having a composition represented by the following formula (1).

[0080] [Chemical Formula 1]

[0081]

[0082] The thickness of the third layer 106b is preferably, for example, about 1 nm to 10 nm. If the third layer 106b is thicker than 10 nm, the energy barrier becomes too thick, and a sufficient tunneling probability cannot be obtained, hindering the amplification of photocurrent in the photoelectric conversion layer 103b. In addition, if the third layer 106b is thinner than 1 nm, tunneling current can flow even when no light is irradiated and the band is not bent, rendering the photodetection function of the photoelectric conversion layer 103b meaningless.

[0083] It should be noted that the photoelectric conversion element, which is formed by stacking a second layer 105 composed of a composite of core-shell particles 10 and perovskite structures and a third layer 106b composed of a condensate or thin film containing organometallic complexes as the main component, is disposed between the hole transport layer and the electron transport layer, and can thus be effectively used as a photoelectric conversion element.

[0084] (Band structure)

[0085] Figure 5 (a) through (d) show the band structure of each layer of the photoelectric conversion element 100 according to this embodiment during operation. Here, 106A represents the inorganic transition metal ion of the third layer 106b, and 106B represents the organic ligand of the third layer 106b.

[0086] In the absence of illumination, the conduction band level of the third layer 106b is higher on the positive electrode layer 101 side than the Fermi level of the positive electrode layer 101, such as... Figure 5 As shown in (a), the current from the positive electrode layer 101 toward the negative electrode layer 102 is blocked.

[0087] When light L1 with a wavelength greater than 800 nm shines on the photoelectric conversion element, the core (inorganic nanoparticles 11) of the core-shell particles 10 constituting the second layer 105 absorbs the light and converts the wavelength into visible light. The perovskite structure absorbs the wavelength-converted light, generating electrons e and holes h. Electrons e move to the conduction band E. c2 Hole h moves to valence band E v2 ( Figure 5 (b)

[0088] At this point, the conduction band energy levels E of the first layer 104a, the second layer 105, and the third layer 106b are... c1 E c2 E c3 Located in E c3 >E c2 >E c1 Therefore, electrons e generated in the second layer 105 and moving to the conduction band of the same layer move to the conduction band E of the first layer 104a, which becomes a lower energy state. c1 .

[0089] On the other hand, the valence band energy levels E of the first layer 104a, the second layer 105, and the third layer 106b v1 E v2 E v3 Become E v2 >E v1 Layer, E v2 >E v3 Therefore, as Figure 5As shown in (c), holes generated in the second layer and moving to the valence band are captured to the valence band of the second layer, which is a relatively high (low for holes) energy state compared to the first and third layers.

[0090] Due to the influence of trapped and concentrated holes (positive potential), the potential energy of electrons decreases near the valence band of the second layer, and the conduction band energy level also decreases. The closer the conduction band energy level is to the second layer containing trapped holes, the more significant the decrease. Therefore, the conduction band energy level of the third layer becomes lower on the second layer side and sharper on the positive electrode layer side. Consequently, for electrons present in the positive electrode layer 101, the energy barrier of the third layer becomes thinner, as... Figure 6 As shown in (d), tunneling is possible to the negative electrode layer side. That is, multiple electrons (electrons in a state without light irradiation) on the positive electrode side, which are blocked by the energy barrier of the third layer, tunnel (pass through) the energy barrier that thins when light irradiates the photoelectric conversion element, allowing them to flow into the negative electrode side. Therefore, the photoelectric conversion element of this modification can achieve a significant amplification of the current directly generated by the irradiated light.

[0091] (Methods for manufacturing core-shell particles)

[0092] Next, the method for manufacturing the core-shell particles 10 of this disclosure will be described. The method for manufacturing the core-shell particles 10 of this disclosure includes an inorganic nanoparticle synthesis step and a capping layer formation step.

[0093] Inorganic nanoparticle synthesis process

[0094] In the inorganic nanoparticle synthesis process, inorganic nanoparticles 11 are synthesized. The synthesis method for inorganic nanoparticles 11 is not particularly limited; examples include precipitation and hydrothermal synthesis. Specifically, trifluoroacetate is synthesized using Ln (lanthanide) oxides, such as Er₂O₃, Tm₂O₃, Ho₂O₃, Yb₂O₃, or Ln halides, such as ErCl₃, ErF₃, TmCl₃, TmF₃, HoCl₃, HoF₃, etc., as the main raw material. Then, sodium trifluoroacetate and chain-like organic molecules are reacted under a N₂ or Ar atmosphere at high temperatures (100–400 °C). The reaction solution is cooled, and an organic solvent such as ethanol is added as needed. The inorganic nanoparticles 11 are then separated by centrifugation, thus obtaining inorganic nanoparticles 11.

[0095] "Covering layer formation process"

[0096] Next, in the capping layer formation step, a capping layer 12 is formed on the inorganic nanoparticles 11 obtained in the inorganic nanoparticle synthesis step. The method for forming the capping layer 12 is not particularly limited; for example, precipitation or hydrothermal synthesis methods can be used. Specifically, for example, the inorganic nanoparticles 11 are reacted with a solution containing cesium oleate synthesized from cesium carbonate and lead halide (PbX2). The temperature is maintained at 120–200°C under a nitrogen atmosphere. The reacted solution is cooled, and the microparticles are separated by centrifugation. By calcining the separated microparticles (e.g., at 200°C–300°C), core-shell particles are obtained.

[0097] (Manufacturing method of photoelectric conversion element)

[0098] Figure 6 (a) to (e) are cross-sectional views of the object being processed during the manufacturing process of the photoelectric conversion element 100. The photoelectric conversion element 100 can be manufactured mainly through the following steps.

[0099] First, such as Figure 6 As shown in (a), a substrate with a negative electrode layer 102 is prepared for forming the photoelectric conversion layer 103. The negative electrode layer 102 on the substrate uses an electrode component that functions as a negative electrode layer and has transparent conductivity. Here, an example is given where a buffer layer 107 is formed on one side of the negative electrode layer 102, but this buffer layer 107 may not be formed. It should be noted that the buffer layer 107 functions as an electron transport layer or a hole blocking layer. The buffer layer 107 can be formed by coating a solution of material onto the negative electrode layer 102 using a spin coating method or the like and then heating it (to dry it). This heating is preferably performed, for example, at approximately 120 to 450°C for 10 to 60 minutes. The material coating conditions (coating time, etc.) are preferably adjusted so that the thickness of the buffer layer 107 is, for example, 1 to 100 nm.

[0100] Next, as Figure 6 As shown in (b), a first layer 104a is formed on one side of the negative electrode layer 102 (within the presence of the buffer layer 107, separated by the buffer layer 107). This first layer 104a is composed of a plurality of particles (i.e., particles of inorganic semiconductors) 20, which contain inorganic semiconductors as the main component. The first layer 104a can also be formed, similarly to the buffer layer 107, by coating a solution of its material and heating it. This heating can be performed, for example, at about 120 to 450°C for 10 to 60 minutes. Preferably, the material coating conditions (coating time, etc.) are adjusted so that the thickness of the first layer 104a is, for example, about 10 to 1000 nm, preferably about 50 to 500 nm.

[0101] Next, as Figure 6As shown in (c), the second layer 105 is preferably formed by coating the surface of the inorganic semiconductor particles 20 with a solution containing core-shell particles 10 and a perovskite structure as the main component using a spin coating, dip coating, or similar method, and then heating the solution. This heating can be performed, for example, at approximately 40–100°C for 5–10 minutes. The thickness of the second layer 105 is adjusted using the material coating conditions (coating time, etc.). By using a liquid material, a thin film can be formed with less environmental impact compared to using a solid inorganic semiconductor such as silicon.

[0102] Next, as Figure 6 As shown in (d), it is preferable to form a third layer 106 on top of the second layer 105. More specifically, it is preferable to form the third layer 106 by evaporating a material containing a p-type organic semiconductor or inorganic semiconductor as the main component, or by coating a solution of such material, onto the second layer 105 using a spin coating, dip coating, or similar method. In fact, during the formation of the second layer 105, the gaps between the inorganic semiconductor particles 20 that form the first layer 104a are essentially filled. Therefore, the third layer 106 can be formed as a film mainly on the exposed portion of the surface of the second layer 105 on the positive electrode layer 101 side (the side opposite to the negative electrode layer 102).

[0103] In the case where an organometallic complex is formed as the third layer (i.e., the third layer 106b is formed), the coating and heating of the solution are preferably performed in two stages. Specifically, preferably, as the first stage, a solution of an inorganic transition metal such as europium is coated and heated; then, as the second stage, a solution of an organic ligand such as terpyridine is coated and heated. Thus, as a result of performing the formation of the third layer 106b in two stages, the third layer 106b has a structure in which a layer 106A formed of an inorganic transition metal and a layer 106B formed of an organic ligand are sequentially stacked from the second layer 105 side.

[0104] Finally, as Figure 7 As shown in (e), by forming a conductive electrode component (positive electrode layer) 101 that functions as a positive electrode on the third layer 106, the photoelectric conversion element 100 of this embodiment can be obtained.

[0105] In the above-described method for manufacturing a photoelectric conversion element, the case using a porous first layer 104a has been explained. However, a layered first layer 104b can also be manufactured using the same method. The first layer 104b can be formed using known methods such as vapor deposition.

[0106] As described above, the core-shell particle 10 of this embodiment is configured such that the inorganic nanoparticle 11, serving as the core, converts absorbed long-wavelength light such as near-infrared light into short-wavelength light such as visible light and ultraviolet light, while the inorganic perovskite-type material, serving as the shell, reabsorbs the converted light and converts it into electricity. Therefore, according to the core-shell particle 10 of this embodiment, it becomes possible to generate photoelectric conversion or electromotive force from long-wavelength light, a situation that was previously difficult to achieve.

[0107] Furthermore, by fabricating the core-shell particles 10 of this embodiment into a core-shell structure, energy transfer between the closely packed inorganic nanoparticles and the inorganic perovskite-type material can be reliably and effectively achieved, reducing energy loss. Therefore, even if the light absorbed by the core is weak, excellent photosensitization properties can be achieved.

[0108] Example

[0109] The effects of the present invention are further illustrated below through embodiments. It should be noted that the present invention is not limited to the following embodiments and can be implemented with appropriate modifications without departing from its spirit.

[0110] (The manufacture of core-shell particles)

[0111] The core-shell particles are manufactured according to the above-described method, specifically under the following conditions.

[0112] (Nuclear-shell particle 1)

[0113] Inorganic nanoparticles, serving as the core-shell particles, were synthesized using a precipitation method. Specifically, 1 mmol of Er oxide (Er₂O₃) was dissolved in 5 mL of trifluoroacetic acid and 5 mL of water, and the mixture was heated and stirred at 80 °C under reduced pressure. 2.5 mmol of sodium trifluoroacetate (NaCOOCF₃) was added to the evaporated and dried powder and dissolved in 15 mL of oleylamine. After stirring at 100 °C under reduced pressure for 30 minutes, nitrogen gas was introduced into the system, and the mixture was stirred at 330 °C for 1 hour. After cooling to 80 °C, 20 mL of ethanol was added, and the NaErF₄ nanoparticles were separated by centrifugation.

[0114] 0.81 g of cesium carbonate (CsCO3) was dissolved in 2.5 mL of oleic acid and 40 mL of octadecene, and stirred at 120 °C for 1 hour under a nitrogen atmosphere. The mixture was then further stirred at 160 °C for 30 minutes to obtain cesium oleate.

[0115] The formation of the capping layer of the synthesized NaErF4 nanoparticles was achieved using a precipitation method. Specifically, 0.4 mmol of PbBr2 and NaErF4 nanoparticles were dispersed in 10 mL of octadecene and stirred at 120 °C for 1 hour under a nitrogen atmosphere. Then, 1 mL of oleic acid and oleylamine were added. After raising the temperature to 180–190 °C, 0.85 mL of cesium oleate was added, and the mixture was stirred for 1 hour. After cooling, the nanoparticles were separated by centrifugation and calcined at 200 °C for 30 minutes to obtain a single-layer core-shell particle (25 nm in diameter). The particle size of the core-shell particles was obtained from SEM images.

[0116] (Nuclear-shell particle 2)

[0117] 0.4 mmol of PbBr2 and the first-layer core-shell particles obtained above were dispersed in 10 mL of octadecene and stirred at 120 °C for 1 hour under a nitrogen atmosphere. Then, 1 mL of oleic acid and oleylamine were added. The temperature was raised to 180–190 °C, and 0.85 mL of cesium oleate was added, followed by stirring for 1 hour. After cooling, the nanoparticles were separated by centrifugation and calcined at 200 °C for 30 minutes to obtain two-layer core-shell particles (30 nm in diameter).

[0118] (Nanoparticle 1)

[0119] Inorganic nanoparticles were synthesized using a precipitation method. Specifically, 1 mmol of Er oxide (Er₂O₃) was dissolved in 5 mL of trifluoroacetic acid and 5 mL of water, and the mixture was heated and stirred at 80 °C under reduced pressure. 2.5 mmol of sodium trifluoroacetate (NaCOOCF₃) was added to the evaporated and dried powder and dissolved in 15 mL of oleylamine. After stirring at 100 °C for 30 minutes under reduced pressure, nitrogen gas was introduced into the system, and the mixture was stirred at 330 °C for 1 hour. After cooling to 80 °C, 20 mL of ethanol was added, and the NaErF₄ nanoparticles (20 nm in diameter) were separated by centrifugation.

[0120] The photoelectric conversion element is manufactured according to the above-described manufacturing method under the following conditions.

[0121] (Example 1)

[0122] As a component serving as the negative electrode layer on a substrate, a component substantially composed of antimony-doped indium oxide (ATO) was prepared. On one side of this component, 200 μl of a 10 mM solution of ethanol (C2H5OH) containing europium chloride hydrate (EuCl3·6H2O) was spin-coated at 3000 rpm. Next, the spin-coated mixture was sequentially heated at 120°C for 10 minutes and then at 450°C for 1 hour to form a buffer layer substantially composed of europium oxide (Eu2O3).

[0123] Next, for the buffer layer, 120 μl of a mixture containing titanium dioxide (TiO2) paste (PST18NR, manufactured by Nippon Chemi-Conduct, Inc.) and ethanol at a weight ratio of 1:3.5 was spin-coated at 6000 rpm. Then, the spin-coated mixture was sequentially heated at 120°C for 10 minutes and then at 450°C for 1 hour to form a first layer (porous membrane) containing multiple particles substantially composed of titanium dioxide.

[0124] Next, for the first porous membrane, 100 μl of a mixed solution containing 1M lead iodide (PbI2), 1M cesium iodide (CsI), 8% by weight (w%) core-shell particles 1, dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) at a concentration of 0.5M or less was spin-coated at 5000 rpm. Then, the spin-coated mixture was heated at 185°C for 15 minutes to form a second layer containing the core-shell particles of the present invention.

[0125] Next, for the second layer, 100 μl of isopropanol (IPA) solution containing europium chloride (EuCl3) at a concentration of 5 mM was spin-coated at 5000 rpm. The spin-coated mixture was then heated at 100°C for 15 minutes to form a layer substantially composed of europium.

[0126] Next, for the europium-based layer, 200 μl of isopropanol (IPA) liquid containing 20 mM terpyridine (2,2':6',2”-terpyridine) was held for 30 seconds and then spin-coated at 3000 rpm. The spin-coated mixture was then heated at 100°C for 15 minutes to form a layer substantially composed of terpyridine.

[0127] Finally, a positive electrode layer (Ag) is formed (vaporized) on the side opposite to the negative electrode layer, in connection with the third layer, through the stack formed by the first, second and third layers, thereby manufacturing the photoelectric conversion element of Example 1.

[0128] (Example 2)

[0129] Except for using core-shell particles 2 instead of core-shell particles 1, a photoelectric conversion element was manufactured under the same conditions as in Example 1.

[0130] (Example 3)

[0131] Except for forming a BCP layer (30 nm thick) as a third layer using vacuum evaporation, a photoelectric conversion element was manufactured under the same conditions as in Example 1.

[0132] (Example 4)

[0133] Except for forming a layer (100 nm thick) substantially composed of Spiro-OMeTAD as a third layer, the photoelectric conversion element was manufactured under the same conditions as in Example 1.

[0134] (Comparative Example 1)

[0135] Except for using nanoparticles 1 instead of core-shell particles 1, photoelectric conversion elements were manufactured under the same conditions as in Example 1.

[0136] (Luminescence spectrum of core-shell particles)

[0137] For each of the core-shell particles 1-2 and nanoparticle 1, the spectra of near-infrared light with a wavelength of 980 nm were measured using an absolute PL quantum yield measuring device manufactured by Hamamatsu Photonics.

[0138] (Optical absorption spectrum of core-shell particles)

[0139] The optical absorption spectrum of core-shell particle 2 was determined using an absolute PL quantum yield measurement apparatus manufactured by Hamamatsu Photonics.

[0140] (SEM observation)

[0141] The cross-section of the photoelectric conversion element of Example 2 was observed at 150,000x using a scanning electron microscope manufactured by Hitachi High-Technologies Corporation, and SEM images were obtained.

[0142] (Photocurrent response characteristics)

[0143] For Example 2, the photoresponse characteristics were measured. The voltage applied between the positive and negative electrode layers of the photoelectric conversion element was -0.5V. The wavelength and irradiance of the light irradiating the photoelectric conversion element were 808 nm and 10 mW / cm², respectively. 2 .

[0144] Figure 8This graph shows the spectra of light obtained by irradiating the photoelectric conversion elements of core-shell particles 1 and 2 with near-infrared light at a wavelength of 980 nm and performing wavelength conversion at this point. The horizontal axis of the graph represents wavelength (nm), and the vertical axis represents intensity (Counts / s). Since peaks are shown at three wavelengths (around 550 nm, around 650 nm, and around 800 nm), it can be seen that the irradiated near-infrared light is converted into these three wavelengths. The dashed line represents the spectrum of the case with two layers of CsPbBr3 capping layer (core-shell particle 2), and the dotted line represents the spectrum of the case with one layer of CsPbBr3 capping layer (core-shell particle 1). It should be noted that, for comparison, the spectrum of NaErF4 (solid line) of nanoparticle 1 alone is also shown. In terms of its luminescence intensity, it is significantly enhanced by the CsPbBr3 capping layer, and further enhanced by the increase of the layer thickness. The results showed that, in the case of inorganic nanoparticles alone, luminescence was deactivated due to the thermal vibration of chain-like organic molecules; conversely, the CsPbBr3 capping layer suppressed the deactivation. It should be noted that the peak position can be adjusted by changing the material, shape, and size of the core-shell particles.

[0145] Figure 9 A graph illustrating the variation in absorptivity caused by the different structures of the core-shell particles in the second layer is shown. The horizontal axis of the graph represents wavelength (nm), and the vertical axis represents intensity (counts / s). The solid line represents the results for core-shell particles 2. For comparison, the absorptivity of NaYF4 nanoparticles containing 2% Er ions is also shown (dashed line). With core-shell particles 2, the amount of Er ions is 100%, therefore the intensity of the irradiated near-infrared light is reduced to about one-seventh compared to typical upconversion nanoparticles (using 2% Er). It is assumed that the near-infrared light commensurate with the reduced intensity is absorbed by the core (inorganic nanoparticle) of the core-shell particles.

[0146] Figure 10 This is a SEM image of a cross-section of a photoelectric conversion element manufactured as an example. It can be seen that a structure consisting of a first layer, a second layer, and a third layer stacked sequentially is formed, creating a current path connecting the Ag-ATO electrodes.

[0147] Figure 7 This graph illustrates the spectrum of light obtained by irradiating the second layer of the photoelectric conversion element of Example 2 with near-infrared light of wavelength 980 nm and performing wavelength conversion thereon. The horizontal axis of the graph represents wavelength (nm), and the vertical axis represents intensity (Counts / s). Normally, the perovskite layer (here, CsPbI3) cannot absorb light above 800 nm, but in the second layer of Example 2, by including core-shell particles 2, it is possible to convert 980 nm light into... Figure 11The visible light shown is luminescence. Emission from CsPbI3 was observed near 700 nm, indicating that CsPbI3 absorbed the visible light obtained by wavelength conversion from core-shell particles 2.

[0148] ​ This graph illustrates the response speed of the photocurrent obtained by irradiating the photoelectric conversion element of Example 2 with light at a predetermined time point. The horizontal axis of the graph represents the elapsed time (s), and the vertical axis represents the photocurrent (A / cm²). 2 The photocurrent display shows an instantaneous rise and fall as the voltage is switched on and off, indicating a sufficient response speed. The photoelectric conversion efficiency is 75%, and the sensitivity is 0.49 A / W.

[0149] Explanation of reference numerals in the attached figures

[0150] 10. Core-shell particles

[0151] 11···Inorganic Nanoparticles

[0152] 11a···Particle size of inorganic nanoparticles

[0153] 12···Covering layer

[0154] 12a···Thickness of the covering layer

[0155] 100··· Photoelectric conversion element

[0156] 101··· Positive Electrode Layer

[0157] 102··· Negative Electrode Layer

[0158] 103··· Photoelectric conversion layer

[0159] 104···First Floor

[0160] 105···Second Floor

[0161] 106···Third Floor

[0162] 107··· Buffer Layer

Claims

1. A complex, characterized in that, It is an aggregate or a film containing a perovskite structure as a main component, The aggregate or the film further contains a core-shell particle as another component, the core-shell particle has: An inorganic up-conversion nanoparticle having a wavelength conversion ability of light, the wavelength conversion of the light refers to a wavelength of incident near-infrared light being converted into visible light and being emitted; and A covering layer formed on a surface of the inorganic up-conversion nanoparticle and formed of an inorganic perovskite substance, The core-shell particle has a core-shell structure, The content of the perovskite structure exceeds 50% by volume with respect to the total mass of the aggregate or the film, The coverage of the covering layer on a surface of the inorganic up-conversion nanoparticle possessed by the core-shell particle is 100%.

2. The complex of claim 1, wherein, The near-infrared light is near-infrared light having a wavelength of 800 nm or more.

3. The complex of claim 1, wherein, The inorganic up-conversion nanoparticle contains a rare earth element.

4. The complex according to any one of claims 1 to 3, wherein The core-shell particle is a core-shell particle having an up-conversion function, A particle diameter as a diameter of the inorganic up-conversion nanoparticle is 10 nm to 100 nm, The covering layer is composed of an inorganic perovskite substance having a thickness of 5% or more of the particle diameter of the inorganic up-conversion nanoparticle.

5. The complex according to any one of claims 1 to 3, wherein The inorganic up-conversion nanoparticle is ErYF4, Er-doped NaYF4, Yb-doped NaYF4, or Tm-doped NaYF4, The inorganic perovskite is CsPbX3, where X is CI - , Br - or I - .

6. The complex according to any one of claims 1 to 3, wherein The inorganic up-conversion nanoparticle is ErYF4, Er-doped NaYF4, or Yb-doped NaYF4, The inorganic perovskite substance is CsPbBr3 or CsPbI3.

7. A light-receiving member for a photoelectric conversion element, characterized by It is a layer composed of the composite body described in any one of claims 1 to 6, and a layer composed of an aggregate or a film containing an organic or inorganic semiconductor as a main component, the semiconductor including a metal complex.

8. A photoelectric conversion element, which is made by providing the light-receiving member for a photoelectric conversion element described in claim 7 between a hole-transporting layer and an electron-transporting layer.

9. A photoelectric conversion element characterized by It is made by sequentially laminating a first layer, a second layer, and a third layer, The first layer is composed of a plurality of particles or an aggregate or a film thereof containing an inorganic semiconductor as a main component, The second layer is formed on a surface of the first layer and is composed of the composite body described in any one of claims 1 to 6, The third layer is composed of a plurality of particles or an aggregate or a film thereof containing an organic or inorganic semiconductor as a main component, The semiconductor includes a metal complex, In a conduction band, the energy level of the second layer is higher than that of the first layer, and the energy level of the third layer is higher than that of the second layer.

10. The photoelectric conversion element according to claim 9, wherein The third layer contains an organic metal complex as a main component, and the energy level of the second layer is higher than that of the third layer in a valence band.

11. A method of improving the detection sensitivity to light in the near infrared region, characterized by, Including: A process of irradiating near-infrared light having a wavelength of 800 nm or more to a light-receiving member for a photoelectric conversion element, the light-receiving member for a photoelectric conversion element being made by laminating (a) the composite body described in any one of claims 1 to 3 or (b) a layer composed of the composite body described in any one of claims 1 to 3 and a layer composed of an aggregate or a film containing an organic semiconductor or an inorganic semiconductor as a main component, the semiconductor including a metal complex; and The near-infrared light incident is wavelength-converted into visible light, and the light emitted is reabsorbed by the composite or the light-receiving part of the photoelectric conversion element and converted into electric power.

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