Thin film, method for manufacturing thin film, circularly polarized light detection element, device, and control method

Abstract

The present invention relates to a thin film in which a plurality of inorganic layers comprising a perovskite substance and forming a layered structure are alternately stacked with organic layers, the organic layers being formed at the boundaries between the adjacent inorganic layers by bonding chiral molecules to the inorganic layers via functional groups covalently bonded to asymmetric carbon atoms of the chiral molecules, the perovskite substance comprising two or more types of halide ions.

Description

Thin film, thin film manufacturing method, circular polarization detection element, device, and control method

[0001] The present invention relates to a thin film, a manufacturing method thereof, a circular polarization detection element, a device, and a control method. This application claims priority to Japanese Patent Application No. 2024-073727, filed on April 30, 2024, the contents of which are incorporated herein by reference.

[0002] Polarization image sensors are known that utilize polarization phenomena to visualize information about the structure and properties of various objects. A polarization image sensor includes a polarizer array with multiple groups of four polarizers with different polarization directions, and a photodiode array with multiple photodiodes arranged facing each polarizer group. Linearly polarized light signals transmitted through the four polarizers in the same group are converted into electrical signals by the photodiodes and output as information for one pixel. From the linearly polarized light output signal, three Stokes parameters can be calculated by combining the sum and difference of the intensities of orthogonal polarization components, and these parameters can be used to quantify the state of the transmitted light.

[0003] However, it is difficult to visualize states such as birefringence and stress distribution observed when an object is bent using only the three Stokes parameters obtained using linearly polarized light. It is known that these states can be visualized using Stokes parameters calculated from the intensity of circularly polarized light, and a technology to detect circularly polarized light is needed. Furthermore, detecting circularly polarized light using the above-mentioned polarization image sensor requires an additional wave plate, which results in a significant decrease in sensitivity. Therefore, a technology to directly detect circularly polarized light is needed. To directly detect circularly polarized light, a new thin film that induces a large chiral structure throughout the entire system is needed.

[0004] Patent Document 1 discloses a thin film made of a perovskite-type material, the thin film comprising a plurality of inorganic layers constituting a layered structure and / or a plurality of inorganic chains constituting a chain structure, and chiral molecules contained in at least a portion of the boundaries between adjacent inorganic layers and / or adjacent inorganic chains, the chiral molecules being either S-chiral molecules or R-chiral molecules, or the abundance ratio of either is higher than the abundance ratio of the other, and the crystalline structure of the perovskite-type material being oriented in a predetermined direction. It is also disclosed that the thin film is capable of directly detecting circularly polarized light over a wide wavelength range.

[0005] International Publication No. 2021 / 241554

[0006] Thin films are being sought that have a wider variety of functions. For example, if the chirality of detectable circularly polarized light in a thin film is inverted, it will be possible to obtain information about the rotation direction of circularly polarized light, which has not been possible to ascertain until now. In other words, thin films with controlled chirality of detectable circularly polarized light are being sought.

[0007] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a thin film in which the chirality of detectable circularly polarized light is controlled, a method for manufacturing the thin film, a circular polarization detection element including the thin film, a device including the circular polarization detection element, and a method for controlling the chirality of circularly polarized light using the thin film.

[0008] In order to solve the above problems, the present invention has the following aspects: [1] A thin film for detecting circularly polarized light, which is made of a perovskite-type substance and is composed of a plurality of inorganic layers constituting a layer structure and an organic layer formed by bonding chiral molecules to the inorganic layers at the boundaries between adjacent inorganic layers via functional groups covalently bonded to asymmetric carbon atoms constituting the chiral molecules, stacked alternately, wherein the chiral molecules are either S-chiral molecules or R-chiral molecules, or the abundance ratio of either is higher than the abundance ratio of the other, the crystal structure of the perovskite-type substance is oriented in a certain direction, and the perovskite-type substance and the chiral molecules are arranged in an A-structure composed of three types of ions A, B, and X. ２ BX４ wherein the ion B and the ion X form a plurality of units having an octahedral structure, and the octahedral structures of adjacent units share one vertex; the ion A is an ion of an aromatic compound containing an alkylammonium ion; the ion B is a lead ion or a tin ion; and the ion X is a first halogen ion X １ and a second halogen ion X ２ wherein the first halogen ion X １ is one kind of halogen ion, and the second halogen ion X ２ are one or more types, and the first halogen ion X １ and the ionic radius of the second halogen ion X ２ [2] The ionic radius of the first halogen ion X is different from that of the first halogen ion X. １ and the second halogen ion X ２ The thin film according to [1], wherein the combination of the first halogen ion X and the second halogen ion X is a combination of halogen ions having a difference in ionic radius of 5% or more. １ and the second halogen ion X ２ The thin film according to [1] or [2], wherein the difference in ionic radius between the first halogen ion X and the second halogen ion X is 7% or more, 10% or more, 5 to 30%, 7 to 30%, or 10 to 20%. １ and the second halogen ion X ２ The thin film according to any one of [1] to [3], wherein the combination of the first halogen ion X and the second halogen ion X is a combination of halogen ions having an ionic radius difference of 0.1 Å or more. １ and the second halogen ion X ２ The thin film according to any one of [1] to [4], wherein the combination of the first halogen ion X and the second halogen ion X is a combination of halogen ions having an ionic radius difference of 0.15 Å or more, 0.2 Å or more, 0.1 to 0.6 Å, 0.15 to 0.6 Å, or 0.2 to 0.4 Å. [6] １ is an iodine ion, and the second halogen ion X ２The thin film according to any one of [1] to [5], wherein the first halogen ion X is either a bromide ion or a chloride ion, or both. [7] The thin film according to any one of [1] to [6], wherein the alkyl ammonium ion contained in the ion A is an ethyl ammonium ion. [8] The thin film according to any one of [1] to [6], wherein the first halogen ion X is either a bromide ion or a chloride ion, or both. １ and the second halogen ion X ２ The abundance ratio (molar ratio) of X １ :X ２ The thin film according to any one of [1] to [7], wherein the ratio of the first halogen ions X to the first halogen ions X is 1:0.5 to 1:5. １ and the second halogen ion X ２ The abundance ratio (molar ratio) of X １ :X ２

[10] The thin film according to any one of [1] to [8], wherein the absorption intensity per unit thickness is 50,000 cm －１ More than 500,000cm －１

[11] The thin film according to any one of [1] to [9], wherein the surface roughness Ra is 1 nm or more and 30 nm or less.

[12] Use of the thin film according to any one of [1] to

[11] as a circular polarization detector.

[0009]

[13] The method for producing a thin film according to any one of [1] to

[11] , wherein the ions A and the first halogen ions X １ AX, a chiral molecule halide composed of １ and the ion B and the second halogen ion X ２ BX is a precursor material for perovskite-type materials composed of ２ a dissolving step of dissolving the compound A in a solvent while heating; a coating film forming step of applying the solution obtained in the dissolving step onto a substrate by a spin coating method to form a coating film on the substrate, the coating film being made of a precursor of a perovskite-type substance; and a heat treatment of the obtained coating film, by which the perovskite-type substance and the chiral molecule are combined into a compound A composed of three types of ions A, B, and X. ２ BX ４and forming a thin film having the ions A and the first halogen ions X. １ AX, a chiral molecule halide composed of １ a precursor raw material synthesis step for synthesizing the ion B and the second halogen ion X ２ BX is a precursor material for perovskite-type materials composed of ２ and a halide synthesis step of synthesizing the compound.

[0010]

[15] A circular polarization detection element comprising the thin film according to any one of [1] to

[11] .

[16] The circular polarization detection element according to

[15] , which is formed by laminating an anode layer, the thin film, and a cathode layer in this order, and at least one of the anode layer and the cathode layer is optically transparent.

[17] A device incorporating the circular polarization detection element according to

[15] .

[18] A device incorporating the circular polarization detection element according to

[16] .

[0011]

[19] A method for controlling the chirality of circularly polarized light detected by a circular polarization detection device, the method comprising the step of placing the thin film according to any one of [1] to

[11] as a light-receiving layer of the circular polarization detection device.

[0012] According to the present invention, it is possible to provide a thin film in which the chirality of detectable circularly polarized light is controlled, a method for manufacturing the thin film, a circularly polarized light detection element including the thin film, a device including the circularly polarized light detection element, and a method for controlling the chirality of circularly polarized light using the thin film.

[0013] 1 is a cross-sectional view of a thin film according to one embodiment of the present invention; 2 is a cross-sectional view of a circular polarization detection element according to one embodiment of the present invention; 3 is an XRD pattern of the thin films of Examples 1 to 4 and Comparative Examples 1 and 2; 4 is a circular dichroism spectrum of the thin films of Examples 1 to 4 and Comparative Examples 1 and 2.

[0014] The following describes in detail the embodiments of the present invention. However, the following description is merely an example of an embodiment of the present invention, and the present invention is not limited to these details and can be modified and implemented within the scope of its gist. The drawings used in the following description may show characteristic portions enlarged for convenience in order to make the features easier to understand, and the dimensional ratios of each component may not necessarily 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 to these and can be modified as appropriate within the scope of its gist.

[0015] <<Thin Film>> The thin film of this embodiment is a thin film for detecting circularly polarized light. The thin film is a thin film in which multiple inorganic layers and multiple organic layers are alternately stacked. The inorganic layers are made of a perovskite-type material and form a layered structure. The organic layers are formed by bonding chiral molecules to the inorganic layers at the boundaries between adjacent inorganic layers via functional groups covalently bonded to asymmetric carbon atoms constituting the chiral molecules. The chiral molecules may contain only either S-chiral molecules or R-chiral molecules. When both S-chiral molecules and R-chiral molecules are contained, the abundance ratio (molar ratio) of one is higher than the abundance ratio of the other. The crystal structure of the perovskite-type material is oriented in a certain direction. Here, "oriented in a certain direction" means, for example, that the crystal structure exists in a substantially regular and substantially uniform state in a direction determined within a specific range. The perovskite-type material and the chiral molecules are oriented in a certain direction, such as an A structure composed of three types of ions A, B, and X. ２ BX ４ The ion B and the ion X form a plurality of units having an octahedral structure, and the octahedral structures of adjacent units share one vertex. The ion A is an ion of an aromatic compound containing an alkylammonium ion. The ion B is a lead ion or a tin ion. The ion X is a first halogen ion X. １ and a second halogen ion X ２ The first halogen ion X １The second halogen ion X ２ The first halogen ion X may be one type or two or more types. １ and the ionic radius of the second halogen ion X ２ The ionic radius is different from that of the

[0016] FIG. 1 is a cross-sectional view schematically illustrating the configuration of a thin film 100 according to this embodiment. The thin film 100 is a thin film for detecting circularly polarized light, and is made of a perovskite-type material to which chirality has been imparted. The thin film 100 is primarily made of a perovskite-type material 101, and includes a plurality of inorganic layers 102 constituting a layered structure, and chiral molecules 103. Note that FIG. 1 illustrates an example in which an amino group (specifically, for example, an ethylamine group) is used as the functional group of the chiral molecule 103, but the present invention is not limited to an ethylamino group.

[0017] Each inorganic layer 102 is a sheet having a thickness of about 1 nm, and is made of a compound A consisting of three types of ions A, B, and X. ２ BX ４ The perovskite-type material is composed of a plurality of perovskite-type materials that form a polycrystalline structure and are part of the perovskite-type material. The crystal structure of the perovskite-type material has a texture and is oriented in a certain direction. Specifically, ions B and X are arranged in a plurality of units (BX) that have an octahedral structure. ６ ) ４－ The octahedral structures of adjacent units share one vertex. Ion B is located at the center of the octahedron, and ion X is located at a vertex of the octahedron. Ion A is located at a position circumscribing the octahedral structure of each unit. Ion A is a chiral molecule 103. In other words, the perovskite-type material and the chiral molecule 103 are compound A, which is composed of three types of ions A, B, and X. ２ BX ４ and constitutes the

[0018] The inorganic layer 102 is arranged by octahedral structures sharing their vertices, and chiral molecules 103 are incorporated between the layers. This results in a structure different from the structure in which the octahedral structures are arranged by sharing their faces (a structure capable of directly detecting circularly polarized light in a wavelength range around 400 nm), causing a change in the absorption position. As a result, it is possible to impart the ability to directly detect circularly polarized light in a wavelength range extended to 500 nm or more. Furthermore, by the octahedral structures sharing their vertices, it is possible to increase the circularly polarized light absorption ability.

[0019] Ion A is an ion of an aromatic compound containing an alkylammonium ion. As the alkylammonium, an alkylammonium ion having 2 to 4 carbon atoms is preferred, with ethylammonium ion, propylammonium ion, butylammonium ion, and isobutylammonium ion being more preferred, and ethylammonium ion being even more preferred. Examples of aromatic compounds include benzene, naphthalene, and anthracene, with naphthalene being preferred. Ion A preferably has a structure in which the carbon atom of the alkyl group of the alkylammonium ion is bonded to an aromatic ring. Ion B is a lead ion or a tin ion.

[0020] In this embodiment, the ions X are first halogen ions X １ and a second halogen ion X ２ The first halogen ion X １ There is one type of second halogen ion X ２ The first halogen ion X may be one kind or two or more kinds. That is, the ion X includes two or more kinds of halogen ions. １ and the ionic radius of the second halogen ion X ２ The ionic radius of the second halogen ion X ２ When there are two or more types of halogen ions, the first halogen ion X １ and a plurality of second halogen ions X ２ The ionic radius of the second halogen ion X ２ When there are two or more types of second halogen ions X ２ The ionic radii are also different.

[0021] Examples of halogen ions include chloride ions, bromide ions, and iodide ions. The ionic radius of a chloride ion is 1.81 Å. The ionic radius of a bromide ion is 1.96 Å. The ionic radius of an iodide ion is 2.20 Å.

[0022] First halogen ion X １ and a second halogen ion X ２ As a combination of halogen ions, a combination of halogen ions with a difference in ionic radius of 5% or more is preferred. The difference is preferably 7% or more, more preferably 10% or more. The difference is preferably 30% or less, more preferably 20% or less. The difference is preferably 5 to 30%, more preferably 7 to 30%, and even more preferably 10 to 20%.

[0023] The denominator for calculating the difference in ionic radius is the molecular radius of the halogen ion with the larger ionic radius. For example, for the first halogen ion X １ is an iodide ion, and the second halogen ion X ２ If the ion is an iodine ion, the result is (2.20 Å - 1.96 Å) / 2.20 Å x 100 = 11%.

[0024] Second halogen ion X ２ When there are two or more halogen ions, the first halogen ion X １ and a plurality of second halogen ions X ２ The difference between the ionic radius of at least one of the first halogen ions X and ... １ and a plurality of second halogen ions X ２ It is preferable that the difference in all ionic radii is 5% or more.

[0025] First halogen ion X １ and a second halogen ion X ２As a combination of these, a combination of halogen ions with a difference in ionic radius of 0.1 Å or more is preferred. The difference is preferably 0.15 Å or more, and more preferably 0.2 Å or more. The difference is preferably 0.6 Å or less, and more preferably 0.4 Å or less. The difference is preferably 0.1 to 0.6 Å, more preferably 0.15 to 0.6 Å, and even more preferably 0.2 to 0.4 Å.

[0026] Second halogen ion X ２ When there are two or more halogen ions, the first halogen ion X １ and a plurality of second halogen ions X ２ The difference between the ionic radius of at least one of the first halogen ions X and the ionic radius of the second halogen ion X is 0.1 Å or more. １ and a plurality of second halogen ions X ２ It is preferable that the difference between all the ionic radii is 0.1 Å or more.

[0027] First halogen ion X １ and a second halogen ion X ２ The combinations with X include the following: Combination 1 X １ : iodine ion, X ２ : Chlorine ion Combination 2 X １ : iodine ion, X ２ : Bromine ion Combination 3 X １ : iodine ion, X ２ : Chlorine ion, bromine ion Combination 4 X １ : Chloride ion, X ２ : Iodine ion Combination 5 X １ : Chloride ion, X ２ : Bromine ion Combination 6 X １ : Chloride ion, X ２ : Iodine ion, bromine ion Combination 7 X １ : Bromine ion, X ２ : Iodine ion Combination 8 X １ : Bromine ion, X ２ : Chlorine ion Combination 9 X １ : Bromine ion, X ２: Iodine ion, chloride ion Note that combinations 1 and 4, combinations 2 and 7, and combinations 5 and 8 are treated as the same combination. Among the above, combinations 1 to 3 are preferred, combinations 1 and 2 are more preferred, and combination 2 is most preferred.

[0028] First halogen ion X １ and the second halogen ion X ２ The abundance ratio (molar ratio) of X １ :X ２ is preferably 1:0.5 to 1:5, more preferably 1:0.5 to 1:3.

[0029] The chiral molecules 103 are contained in at least a portion of the boundary 104 between adjacent inorganic layers 102, and are bonded to and fixed to the perovskite-type material on the surface of the inorganic layer 102. More specifically, the chiral molecules 103 are bonded to the perovskite-type material via a functional group covalently bonded to an asymmetric carbon atom constituting the chiral molecules 103. This functional group is a substituent that can have an electric charge, and the substituent and the perovskite-type material can form a bond via a halogen ion. The functional group is preferably an amino group. The amino group (NH ３ ＋ ) is, for example, (PbI ６ ) ４－ I － By bonding with (PbI ６ ) ４－ Chirality is generated in the inorganic layer, and a new circularly polarized light absorption ability is exhibited. The chiral molecule 103, which is an aromatic compound, preferably has one or more, preferably two or more, aromatic monocycles (i.e., benzene rings) forming an aromatic ring (i.e., a polycyclic aromatic compound). Furthermore, if the aromatic ring is an aromatic ring having a structure in which one side of the benzene ring is shared, such as a naphthalene ring or an anthracene ring, the circularly polarized light absorption intensity is increased, which is preferable.

[0030] The chiral molecule 103 exists in an R-configuration and an S-configuration. The R-configuration or S-configuration chiral molecule 103 strongly absorbs either right-handed or left-handed circularly polarized light. Here, an R-configuration is one in which four different bonding groups are bonded to an asymmetric carbon, with the one with the smallest atomic number placed furthest away and the remaining three bonding groups arranged clockwise from largest to smallest atomic number, and an S-configuration is one in which they are arranged counterclockwise. An example of an R-configuration is R-(+)-1-(1-naphthyl)ethylamine hydroiodide shown in formula (1) below. An example of an S-configuration is S-(-)-1-(1-naphthyl)ethylamine hydroiodide shown in formula (2) below.

[0031]

[0032]

[0033] When the chiral molecule 103 reacts with one molecule of ion B in the inorganic layer 102 at a ratio of 1.2 molecules or more, a layer structure (A ２ BX ４ On the other hand, when the chiral molecule 103 reacts with one molecule of ion B in the inorganic layer 102 at a ratio of 0.75 molecules or less, a chain structure (ABX ３ When the chiral molecule 103 reacts with one molecule of ion B in the inorganic layer 102 at a ratio of more than 0.75 molecules and less than 1.2 molecules, a structure in which a chain structure and a layer structure are mixed is usually formed. In the case of a structure in which a chain structure and a layer structure are mixed, the perovskite-type substance and the chiral molecule react with a compound A composed of three types of ions A, B, and X. ２ BX ４ and ABX ３ The thin film of this embodiment is a thin film obtained by reaction of 1.2 or more molecules of the chiral molecule 103 with one molecule of the ion B in the inorganic layer 102.

[0034] The ions A, B, and X are as described above. By adjusting the ratio of the chiral molecules 103 to the ions B in the inorganic layer 102, the circularly polarized light absorption ability can be adjusted.

[0035] 1 illustrates an example in which the chiral molecules 103 form an organic layer 105 at the boundary 104, and the inorganic layers 102 and the organic layers 105 are alternately laminated. There is no limitation on the number of inorganic layers 102 to be laminated, but from the viewpoint of facilitating the flow of current in the thickness direction when the thin film 100 is used in a circular polarization detection element or the like, it is preferable that the thickness d of the thin film 100 is 100 to 500 nm. Furthermore, from the viewpoint of protecting the chiral molecules 103, it is preferable that the uppermost and lowermost layers be inorganic layers 102.

[0036] In order to allow the irradiated light to be absorbed by the perovskite-type material and to efficiently transmit the irradiated light, the surface roughness Ra (arithmetic mean roughness) of each thin film 100 is preferably 1 nm or more and 30 nm or less. If the arithmetic mean roughness Ra of the thin film 100 is 30 nm or less, leakage from the circular polarization detection element 110 shown in FIG. 2 described below can be suppressed. The arithmetic mean roughness Ra can be measured using, for example, an atomic force microscope (AFM). When measuring using an atomic force microscope, the arithmetic mean roughness Ra can be obtained from an observation image obtained by using, for example, an atomic force microscope manufactured by Shimadzu Corporation, setting the scanning range and scanning mode to appropriate values ​​(specifically, for example, scanning mode: dynamic mode).

[0037] In addition, since the perovskite-type substance needs to efficiently absorb the irradiated light, the absorption intensity per unit thickness of the thin film 100 must be 50,000 cm －１ More than 500,000cm －１ It is desirable that the absorption intensity per unit thickness is the value of the absorption intensity per unit thickness at the peak wavelength of the peak with the highest absorption intensity. The absorption intensity of the thin film 100 is measured by a transmission method.

[0038] <Circular Polarization Detection Element> The circular polarization detection element of this embodiment includes the thin film described above. The circular polarization detection element is formed by laminating an anode layer, a thin film, and a cathode layer in this order, and it is preferable that at least one of the anode layer and the cathode layer is optically transparent. FIG. 2 is a cross-sectional view of a circular polarization detection element 110 including a thin film 100. The circular polarization detection element 110 is mainly a laminate formed by laminating an anode layer 106, a thin film 100, and a cathode layer 107 in this order. At least one of the anode layer 106 and the cathode layer 107 is optically transparent so that the perovskite material in the thin film 100 absorbs light (circularly polarized light). The anode layer 106 is formed by laminating an anode layer 106, a thin film 100, and a cathode layer 107 on one side in the thickness direction of the thin film 100, and the anode layer 106 is formed by laminating an anode layer 106, a thin film 100, and a cathode layer 107 on the other side in the thickness direction of the thin film 100. ２ , TiO ２ The cathode layer 107 is bonded to the other side in the thickness direction of the thin film 100 via a cathode-side adhesive layer 108 (electron transport layer) made of, for example, BCP (Bathocuproine (registered trademark)), spiro-MeOTAD, TPD, or the like. When the anode layer 106 is optically transparent, the anode-side adhesive layer 108 is also optically transparent. When the cathode layer 107 is optically transparent, the cathode-side adhesive layer 109 is also optically transparent.

[0039] In the circular polarization detection element 110, the inorganic layer 102 constituting the thin film 100 has a polycrystalline structure, and therefore the light absorption of the thin film 100 is large (absorption intensity at a wavelength of 488 nm: approximately 50,000 cm －１ 1 μm or more) and has high conductivity (carrier diffusion length, about 1 μm or more). Therefore, when the light irradiated onto the thin film 100 is circularly polarized or contains circularly polarized light, it is possible to detect a current caused by the absorbed circularly polarized light. Note that by using only R- or S-form chiral molecules, it is possible to induce a chiral structure of R- or S-configuration in the perovskite structure, selectively absorb right-handed circularly polarized light or left-handed circularly polarized light, and detect the resulting current. Furthermore, even when the abundance ratio of either the R- or S-form is higher than the abundance ratio of the other, it is possible to induce a chiral structure of R- or S-configuration in the perovskite structure, selectively absorb right-handed circularly polarized light or left-handed circularly polarized light, and detect the resulting current. Furthermore, by using the thin film of this embodiment, it is possible to selectively absorb the first halogen ion X １and a second halogen ion X ２ By adjusting the combination of the above and the molar ratio thereof, the chirality of the circularly polarized light that can be detected by the thin film can be controlled. Furthermore, the polarity of the electric signal based on the detected current can be reversed from plus to minus in response to the inversion of chirality caused by the inversion of the chiral structure as described above. Such an effect can be advantageously utilized for the detection of chirality by the thin film.

[0040] <<Method for Producing Thin Film>> In the method for producing a thin film of this embodiment, the ions A and the first halogen ions X １ AX, a chiral molecule halide composed of １ and the ion B and the second halogen ion X ２ BX is a precursor material for perovskite-type materials composed of ２ a dissolving step of dissolving the compound A in a solvent while heating; a coating film forming step of applying the solution obtained in the dissolving step onto a substrate by a spin coating method to form a coating film on the substrate, the coating film being made of a precursor of a perovskite-type substance; and a heat treatment of the obtained coating film, by which the perovskite-type substance and the chiral molecule are combined into a compound A composed of three types of ions A, B, and X. ２ BX ４ and forming a thin film having the following structure: １ In addition, AX ２ Similarly, BX may be used as a precursor material for the perovskite-type substance. ２ In addition, BX １ In addition, in the above-mentioned manufacturing method, the ion A and the first halogen ion X may be used in combination. １ AX, a chiral molecule halide composed of １ a precursor raw material synthesis step for synthesizing the ion B and the second halogen ion X ２ BX is a precursor material for perovskite-type materials composed of ２The precursor raw material synthesis step and the halide synthesis step may be carried out in any order, or may be carried out simultaneously.

[0041] (Precursor Raw Material Synthesis Process) Precursor BX ２ B in the formula is a lead ion or a tin ion. ２ X ２ is a chloride ion, a bromide ion, or an iodide ion, with an iodide ion being preferred. ２ The synthesis of precursor BX can be carried out by methods known in the art. １ Precursor BX ２ can be synthesized in the same way.

[0042] (Halide synthesis step) Chiral molecule halide AX １ A in the formula (1) is a precursor of the chiral molecule. For example, R-(+)-1-(1-naphthyl)ethylamine hydroiodide represented by the formula (1) is AX １ In this case, the precursor of the chiral molecule is R-(+)-1-(1-naphthyl)ethylamine. １ In this case, the precursor of the chiral molecule is S-(+)-1-(1-naphthyl)ethylamine. １ ) to give AX １ The chiral molecule halide AX is synthesized. １ X １ is a chloride ion, a bromide ion, or an iodide ion, with a bromide ion being preferred. ２ Chiral molecule halide AX １ can be synthesized in the same way.

[0043] (Dissolving step) In the dissolving step, BX, which is a precursor raw material, is dissolved. ２ and the halide AX １The precursor BX is dissolved in a solvent under heating. Examples of the solvent that can be used include dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and γ-butyrolactone. ２ The concentration of the halide AX in the solution is preferably 0.5 to 2 mol / L, more preferably 0.75 to 1.5 mol / L, and even more preferably 0.75 to 1.25 mol / L. １ The concentration of the halide AX is preferably 0.5 to 2 mol / L, more preferably 0.75 to 2.0 mol / L, and even more preferably 0.75 to 1.5 mol / L. In the dissolving step, an organic halide that can be sublimated by heating and reacts with some of the constituent elements of the perovskite-type material may be added. When an organic halide is added, it is preferable to add it to a concentration of, for example, 1 mol / L or less, preferably 0.4 mol / L to 0.8 mol / L, and dissolve it. Note that, when a layered structure is substantially formed, the ratio of the chiral molecule is calculated so that there are 1.2 or more molecules of the halide AX for one molecule of the ion B in the inorganic layer 102. １ The following are mixed.

[0044] (Coating film formation process) Using a spin coating method, the solution (mixture) obtained in the dissolving process is dropped onto a separately prepared base substrate, and the base substrate is rotated at 1000 rpm to 5000 rpm to form a pre-treatment coating film on the base substrate. The material of the base substrate is not limited.

[0045] (Thin Film Formation Step) Next, the untreated coating film is heated using a heating device to obtain a thin film composed of a polycrystalline inorganic layer and chiral molecules distributed between the layers. If the untreated coating film contains an organic halide, the organic halide will sublimate upon heating. Here, the heating temperature is preferably 70°C to 120°C, and the heating time is preferably 15 to 60 minutes.

[0046] By carrying out the coating film formation process and the thin film formation process without crystallizing the solution obtained in the dissolution process, the inorganic layer 102 of the thin film 100 obtained through the thin film formation process becomes a polycrystalline substance that has a textured structure and is preferentially oriented in a specific direction rather than randomly.

[0047] By forming a positive electrode layer 107 on one side in the thickness direction of the thin film 100 obtained through the thin film formation process and a negative electrode layer 106 on the other side using a known film formation method such as vacuum deposition or sputtering, it is possible to obtain a circular polarization detection element 110 that can output information about circular polarization as an electrical signal. Note that a positive electrode-side adhesive layer 109 and a negative electrode-side adhesive layer 108 may be formed between the thin film 100 and the positive electrode layer 107 and between the thin film 100 and the negative electrode layer 106, respectively, using a known film formation method such as vacuum deposition, spin coating, or sputtering.

[0048] As described above, the thin film 100 of this embodiment is a layered structure in which a plurality of inorganic layers 102 are stacked, and chiral molecules 103 having absorbance for circularly polarized light are immobilized in the two-dimensionally expanding nanospace sandwiched between adjacent inorganic layers 102. The chiral molecules 103 induce chirality in the arrangement of the inorganic layers 102, and therefore the absorption wavelength range of circularly polarized light by the inorganic layers 102 can be expanded to a wide range of 350 to 800 nm.

[0049] Furthermore, since the inorganic layer 102 has a polycrystalline structure and is highly conductive, by connecting electrodes to both ends in the thickness direction, when the light irradiated onto the thin film 100 is circularly polarized or contains circularly polarized light, it is possible to detect a current caused by circularly polarized light absorbed in the inorganic layer 102. That is, the inorganic layer 102 formed using only R-configuration chiral molecules or S-configuration chiral molecules selectively absorbs right-handed circularly polarized light or left-handed circularly polarized light, and the resulting current can be detected.

[0050] Furthermore, the thin film 100 of this embodiment does not require a polarizer or a wave plate to detect circularly polarized light, resulting in a high extinction ratio, making it possible to directly detect circularly polarized light with high sensitivity and high resolution, which was impossible to directly detect with conventional photodetectors.

[0051] Furthermore, by using the thin film of this embodiment, the first halogen ion X １ and a second halogen ion X ２By adjusting the combination of these and their molar ratios, the chirality of circularly polarized light that can be detected by the thin film can be controlled.

[0052] Therefore, the thin film 100 of this embodiment can be used as a circular polarization detection element, and various devices incorporating this thin film, such as a polarization camera, can be realized. By directly detecting circularly polarized light, information such as the intensity distribution of birefringence, which cannot be obtained with linearly polarized light, can be obtained.

[0053] <Method for controlling the chirality of circularly polarized light> The method for controlling the chirality of circularly polarized light detected by the circular polarization detection device of this embodiment includes a step of placing the above-mentioned thin film as a light-receiving layer of the circular polarization detection device. １ and the second halogen ion X ２ The method for controlling the chirality of circularly polarized light is controlled by preparing a plurality of thin films containing perovskite-type materials with different combinations and / or compositions, and switching between the plurality of thin films as light-receiving layers of the circular polarization detection device. A plurality of the thin films may be installed in the circular polarization device in advance, and the thin films to be used may be switched as needed.

[0054] The effects of the present invention will be made clearer by the following examples. Note that the present invention is not limited to the following examples and can be practiced with appropriate modifications within the scope of the present invention.

[0055] Comparative Example 1 1 g of R-(+)-1-(1-naphthyl)ethylamine (R-1-NEA) was mixed with 500 μL of hydrogen iodide (HI), and the resulting mixture was stirred at 0° C. for 2 hours to obtain 2.8 g of R-(+)-1-(1-naphthyl)ethylamine hydroiodide (R-1-NEA)I. Subsequently, 500 μL of dimethylformamide (DMF) was used as a solvent, and lead iodide (PbI) was added to the mixture. ２230 mg of (R-1-NEA)I and 299 mg of (R-1-NEA)I were mixed, and the resulting mixture was stirred at 70°C for 1 hour to prepare a solution containing the raw materials for the thin film. The prepared solution was applied to a separately prepared base substrate, and a pre-treatment coating film was formed by spin coating (two-stage spin conditions: 1000 rpm, 10 s, followed by 5000 rpm, 60 s). 8 seconds after the start of spin coating, 220 μL of chlorobenzene was dropped as a poor solvent. The formed pre-treatment coating film was heated at 100°C for 30 minutes to obtain (R-1-NEA)I. ２ PbI ４ A thin film of 1000 nm was obtained.

[0056] Comparative Example 2 1 g of S-(-)-1-(1-naphthyl)ethylamine (S-1-NEA) was mixed with 500 μL of hydrogen iodide (HI), and the resulting mixture was stirred at 0°C for 2 hours to obtain 2.9 g of S-(+)-1-(1-naphthyl)ethylamine hydroiodide (S-1-NEA)I. Subsequently, 500 μL of dimethylformamide (DMF) was used as a solvent, and lead iodide (PbI) was added to the mixture. ２ 230 mg of (S-1-NEA)I and 299 mg of (S-1-NEA)I were mixed, and the resulting mixture was stirred at 70°C for 1 hour to prepare a solution containing the raw materials for the thin film. Subsequently, spin coating and subsequent heating were carried out in the same manner as in Comparative Example 1 to prepare a solution containing the raw materials for the thin film. ２ PbI ４ A thin film of 1000 nm was obtained.

[0057] Example 1 1 g of R-(+)-1-(1-naphthyl)ethylamine (R-1-NEA) was mixed with 500 μL of hydrogen iodide (HI), and the resulting mixture was stirred at 0° C. for 2 hours to obtain 2.8 g of R-(+)-1-(1-naphthyl)ethylamine hydroiodide (R-1-NEA)I. Subsequently, 500 μL of dimethylformamide (DMF) was used as a solvent, and lead bromide (PbBr ２ 184 mg of (R-1-NEA)I and 299 mg of (R-1-NEA)I were mixed, and the resulting mixture was stirred at 70°C for 1 hour to prepare a solution containing the raw materials for the thin film. Subsequently, spin coating and subsequent heating were carried out in the same manner as in Comparative Example 1 to prepare a solution containing the raw materials for the thin film. ２ PbI２ Br ２ A thin film of 1000 nm was obtained.

[0058] Example 2 1 g of S-(-)-1-(1-naphthyl)ethylamine (S-1-NEA) was mixed with 500 μL of hydrogen iodide (HI), and the resulting mixture was stirred at 0°C for 2 hours to obtain 2.9 g of S-(+)-1-(1-naphthyl)ethylamine hydroiodide (S-1-NEA)I. Subsequently, 500 μL of dimethylformamide (DMF) was used as a solvent, and lead bromide (PbBr ２ 184 mg of (S-1-NEA)I and 299 mg of (S-1-NEA)I were mixed, and the resulting mixture was stirred at 70°C for 1 hour to prepare a solution containing the raw materials for the thin film. Subsequently, spin coating and subsequent heating were carried out in the same manner as in Comparative Example 1 to prepare a solution containing the raw materials for the thin film. ２ PbI ２ Br ２ A thin film of 1000 nm was obtained.

[0059] Example 3 1 g of R-(+)-1-(1-naphthyl)ethylamine (R-1-NEA) was mixed with 500 μL of hydrogen iodide (HI), and the resulting mixture was stirred at 0° C. for 2 hours to obtain 2.8 g of R-(+)-1-(1-naphthyl)ethylamine hydroiodide (R-1-NEA)I. Subsequently, 500 μL of dimethylformamide (DMF) was used as a solvent, and lead bromide (PbBr ２ ) 92 mg, lead iodide (PbI ２ 115 mg of (R-1-NEA)I and 299 mg of (R-1-NEA)I were mixed, and the resulting mixture was stirred at 70°C for 1 hour to prepare a solution containing the raw materials for the thin film. Subsequently, spin coating and subsequent heating were carried out in the same manner as in Comparative Example 1 to prepare a solution containing the raw materials for the thin film. ２ PbIBr ３ A thin film of 1000 nm was obtained.

[0060] Example 4 1 g of S-(-)-1-(1-naphthyl)ethylamine (S-1-NEA) was mixed with 500 μL of hydrogen iodide (HI), and the resulting mixture was stirred at 0°C for 2 hours to obtain 2.9 g of S-(+)-1-(1-naphthyl)ethylamine hydroiodide (S-1-NEA)I. Subsequently, 500 μL of dimethylformamide (DMF) was used as a solvent, and lead bromide (PbBr ２ ) 92 mg, lead iodide (PbI ２ 115 mg of (S-1-NEA)I and 299 mg of (S-1-NEA)I were mixed, and the resulting mixture was stirred at 70°C for 1 hour to prepare a solution containing the raw materials for the thin film. Subsequently, spin coating and subsequent heating were carried out in the same manner as in Comparative Example 1 to prepare a solution containing the raw materials for the thin film. ２ PbIBr ３ A thin film of 1000 nm was obtained.

[0061] (XRD Measurement) For the thin films of Examples 1 to 4 and Comparative Examples 1 and 2, the XRD patterns of each thin film were measured at room temperature using an X-ray diffraction (XRD) method using an X-ray diffraction measuring device, SmartLab 9kW or MiniFlex manufactured by RIGAKU Corporation. For this measurement, a CuKα radiation source was used. The tube voltage and tube current during measurement were 40 kV and 15 mA, respectively. The measurement conditions were an ω of 1.25° and an accumulation time of 10° / min.

[0062] (Circular dichroism spectrum measurement) The thin films of Examples 1 to 4 and Comparative Examples 1 and 2 were measured using a circular dichroism spectrometer (JASCO J-1500) to obtain the circular dichroism spectrum of each thin film.

[0063] The results of XRD analysis of the thin films obtained in Examples 1 to 4 and Comparative Examples 1 and 2 are shown in Figure 3. The horizontal axis of Figure 3 represents the diffraction angle, and the vertical axis of Figure 3 represents the diffraction intensity.

[0064] The thin films of Examples 1 and 2 exhibited periodic diffraction patterns at angles of 4.9°, 9.8°, 14.8°, and 19.8°, corresponding to the (002), (004), (006), and (008) planes, respectively. The interplanar spacing calculated from the Bragg reflection condition (2d sin θ = nλ) was d = 17.8 Å. In other words, it was found that a layered compound was formed with chiral molecules between inorganic layers made of perovskite-type material, with a spacing of 8.9 Å.

[0065] The thin films of Examples 3 and 4 exhibited periodic diffraction patterns at angles of 4.4°, 8.7°, 13.0°, and 17.4°, corresponding to the (002), (004), (006), and (008) planes, respectively. The interplanar spacing calculated from the Bragg reflection condition (2d sin θ = nλ) was d = 20.2 Å. In other words, it was found that a layered compound was formed with chiral molecules between inorganic layers made of perovskite-type material, with a spacing of 10.1 Å.

[0066] The thin films of Comparative Examples 1 and 2 exhibited periodic diffraction patterns at angles of 5.8°, 11.7°, 17.6°, and 23.5°, corresponding to the (002), (004), (006), and (008) planes, respectively. The interplanar spacing calculated from the Bragg reflection condition (2d sin θ = nλ) was d = 15.1 Å. In other words, it was found that a layered compound was formed with chiral molecules inserted between inorganic layers made of perovskite-type material at intervals of 7.55 Å.

[0067] The measurement results of the circular dichroism spectra (CD spectra) of the thin films obtained in Examples 1 to 4 and Comparative Examples 1 and 2 are shown in Fig. 4. The horizontal axis of Fig. 4 represents wavelength, and the vertical axis of Fig. 4 represents CD signal intensity (CD [mdeg] = 32980 × Δ absorbance (the difference in absorption intensity between left-handed circularly polarized light and right-handed circularly polarized light)).

[0068] The thin film of Comparative Example 1 exhibits CD signals of -56 mdeg and +12 mdeg at 488 nm and 505 nm. That is, the thin film of Comparative Example 1 exhibits stronger absorption for right-handed circularly polarized light than for left-handed circularly polarized light at 488 nm, and stronger absorption for left-handed circularly polarized light than for right-handed circularly polarized light at 505 nm. That is, the spin directions of photoelectrons preferentially generated depending on the wavelength are reversed.

[0069] On the other hand, the thin film of Example 1 exhibits a CD signal of +82 mdeg at 462 nm. That is, the thin film of Example 1 exhibits stronger absorption for left-handed circularly polarized light than for right-handed circularly polarized light. Both Comparative Example 1 and Example 1 use R-(+)-1-(1-naphthyl)ethylamine hydroiodide ((R-1-NEA)I), and it was found that the chirality of the circularly polarized light that the thin film can detect is reversed between 450 and 500 nm. That is, the spin directions of the photoelectrons preferentially generated in Comparative Example 1 and Example 1 are opposite.

[0070] Furthermore, the thin film of Example 3 exhibits a CD signal of +12 mdeg at 476 nm. That is, the thin film of Example 3 exhibits stronger absorption for left-handed circularly polarized light than for right-handed circularly polarized light. Both Comparative Example 1 and Example 3 use R-(+)-1-(1-naphthyl)ethylamine hydroiodide ((R-1-NEA)I), and it was found that the chirality of the circularly polarized light that the thin film can detect is reversed between 450 and 500 nm. That is, the spin directions of the photoelectrons preferentially generated in Comparative Example 1 and Example 3 are opposite.

[0071] The thin film of Comparative Example 2 exhibits CD signals of +56 mdeg and -12 mdeg at 488 nm and 505 nm. That is, the thin film of Comparative Example 2 exhibits stronger absorption for left-handed circularly polarized light than for right-handed circularly polarized light at 488 nm, and stronger absorption for right-handed circularly polarized light than for left-handed circularly polarized light at 505 nm. That is, the spin directions of photoelectrons preferentially generated depending on the wavelength are reversed.

[0072] The thin film of Example 2 exhibits a CD signal of +60 mdeg at 477 nm. That is, the thin film of Example 2 also exhibits stronger absorption for left-handed circularly polarized light than for right-handed circularly polarized light. On the other hand, the thin film of Example 2 exhibits a negative CD signal at wavelengths of 420 nm or less. That is, in the wavelength region of 420 nm or less, it exhibits stronger absorption for right-handed circularly polarized light than for left-handed circularly polarized light. That is, the spin direction of photoelectrons preferentially generated depending on the wavelength is opposite. Both Comparative Example 2 and Example 2 use S-(+)-1-(1-naphthyl)ethylamine hydroiodide ((S-1-NEA)I), and it was found that the chirality of circularly polarized light detectable by the thin film is reversed at wavelengths of 420 nm or less. That is, the spin direction of photoelectrons preferentially generated is opposite in Comparative Example 2 and Example 2.

[0073] Furthermore, the thin film of Example 4 exhibits a CD signal of -11 mdeg at 476 nm. That is, the thin film of Example 4 exhibits stronger absorption for right-handed circularly polarized light than for left-handed circularly polarized light. In both Comparative Example 2 and Example 4, S-(+)-1-(1-naphthyl)ethylamine hydroiodide ((S-1-NEA)I) was used, and it was found that the chirality of the circularly polarized light that the thin film can detect is reversed. That is, the spin directions of the photoelectrons preferentially generated are opposite in Comparative Example 2 and Example 4.

[0074] The thin film of the present disclosure has high industrial applicability because the chirality of detectable circularly polarized light can be controlled.

[0075] 100: Thin film, 101: Perovskite-type material, 102: Inorganic layer, 103: Chiral molecule, 104: Boundary, 105: Organic layer, 106: Negative electrode layer, 107: Positive electrode layer, 108: Negative electrode side adhesive layer, 109: Positive electrode side adhesive layer, 110: Circular polarization detection element

Claims

1. A thin film for detecting circularly polarized light, comprising a plurality of inorganic layers made of a perovskite-type substance and constituting a layered structure, and an organic layer formed by bonding chiral molecules to the inorganic layers at the boundaries between adjacent inorganic layers via functional groups covalently bonded to asymmetric carbon atoms constituting the chiral molecules, which are alternately laminated; the chiral molecules are either S-chiral molecules or R-chiral molecules, or the abundance ratio of either is higher than the abundance ratio of the other, the crystal structure of the perovskite-type substance is oriented in a certain direction, and the perovskite-type substance and the chiral molecules are arranged in an A-structure composed of three types of ions A, B, and X. ２ BX ４ wherein the ion B and the ion X form a plurality of units having an octahedral structure, and the octahedral structures of adjacent units share one vertex, the ion A is an ion of an aromatic compound containing an alkylammonium ion, the ion B is a lead ion or a tin ion, and the ion X is a first halogen ion X １ and a second halogen ion X ２ wherein the first halogen ion X １ is one kind of halogen ion, and the second halogen ion X ２ are one or more types, and the first halogen ion X １ and the ionic radius of the second halogen ion X ２ Thin film with different ionic radius.

2. The first halogen ion X １ and the second halogen ion X ２ 2. The thin film according to claim 1, wherein the difference in ionic radius between the halogen ions is 5% or more.

3. The first halogen ion X １ and the second halogen ion X ２ 2. The thin film according to claim 1, wherein the combination of said halogen ions is a combination of halogen ions having an ionic radius difference of 0.1 Å or more.

4. The first halogen ion X １ is an iodine ion, and the second halogen ion X ２ 2. The thin film of claim 1, wherein is one or both of a bromide ion and a chloride ion.

5. The thin film according to claim 1, wherein the alkylammonium ion contained in the ion A is an ethylammonium ion.

6. The first halogen ion X １ and the second halogen ion X ２ The abundance ratio (molar ratio) of X １ :X ２ The thin film according to claim 4, wherein the ratio of the hydroxyl group to the hydroxyl group is 1:0.5 to 1:

5.

7. The absorption intensity per unit thickness is 50,000 cm －１ More than 500,000cm －１ 2. The thin film of claim 1, wherein:

8. The thin film according to claim 1, having a surface roughness Ra of 1 nm or more and 30 nm or less.

9. A method for producing a thin film according to any one of claims 1 to 8, wherein the ions A and the first halogen ions X １ AX, a chiral molecule halide composed of １ and the ion B and the second halogen ion X ２ BX is a precursor material for perovskite-type materials composed of ２ a dissolving step of dissolving the compound A in a solvent while heating it; a coating film forming step of applying the solution obtained in the dissolving step onto a substrate by a spin coating method to form a coating film made of a precursor of a perovskite-type substance on the substrate; and a heat treatment of the resulting coating film to convert the perovskite-type substance and the chiral molecule into a compound A composed of three types of ions A, B, and X. ２ BX ４ and forming a thin film having the above formula (1).

10. The ion A and the first halogen ion X １ AX, a chiral molecule halide composed of １ a precursor raw material synthesis step of synthesizing the ions B and the second halogen ions X ２ BX is a precursor material for perovskite-type materials composed of ２ and a halide synthesis step of synthesizing the compound represented by the formula (I).

11. A circular polarization detection element comprising the thin film according to any one of claims 1 to 8.

12. The circular polarization detection element according to claim 11, wherein a negative electrode layer, the thin film, and a positive electrode layer are laminated in this order, and at least one of the negative electrode layer and the positive electrode layer is optically transparent.

13. A device incorporating the circular polarization detection element of claim 11.

14. A device incorporating the circular polarization detection element of claim 12.

15. A method for controlling the chirality of circularly polarized light detected by a circular polarization detection device, comprising the step of placing the thin film according to any one of claims 1 to 8 as a light-receiving layer of the circular polarization detection device.

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