Color conversion particles

Abstract

The color conversion particle has a core and a shell that contains the core and absorbs excitation light. The color conversion particle receives the irradiated excitation light and emits light at the core or at the interface between the core and the shell. The core is composed of a chalcogenide perovskite, and the core and the shell have a band alignment that exhibits a Stokes shift.

Description

Technical Field

[0001] The present invention relates to color conversion particles. Background Art

[0002] Hitherto, in lighting, display devices, solar cells, etc., color conversion using wavelength conversion (down-conversion) has been widely used, which converts excitation light incident on an object from the outside into light with a longer wavelength and emits it. In such color conversion, for example, a phosphor added with an activator is sometimes used. However, conventional phosphors have limitations in terms of controllability of emission wavelength, emission peak width, and number of peaks (color purity). For example, in applications such as display devices that require high color purity at specific wavelengths, there are many problems that need to be improved.

[0003] On the other hand, in recent years, as a method for solving the above problems, core-shell type quantum dots that utilize quantum effects have attracted attention, and core-shell type quantum dots have gradually been applied to various fields. Core-shell type quantum dots are minute semiconductor particles with a diameter of several nanometers, and have a structure in which a core that functions as a light-emitting part is covered from the outside by a shell that functions as a carrier confinement layer and a light-absorbing part.

[0004] In such core-shell type quantum dots, the material of the core is, for example, selected from Cd(S, Se), InP, APbX 3 (A = Cs, MA; X = Cl, Br, I). In addition, the material of the shell is, for example, Zn(S, Se), A’ 2 PbX 4 (A’ = OA), etc. Here, MA is methylammonium, and OA is octylammonium. In addition, as materials for quantum dots, halide perovskites typified by CsPbBr and chalcogenide perovskites represented by the chemical formula ABX 3 (A = Ca, Sr, Ba; B = Ti, Zr, Hf; X = S, Se, Te) are also known.

[0005] CdSe, which is one of the materials for the above core-shell type quantum dots, contains Cd that is regulated by RoHS and is toxic. Therefore, InP has been developed as an alternative material for Cd(S, Se), but InP has problems in terms of material durability and luminous efficiency in addition to containing rare metal In. In addition, halide perovskites have high absorbance and luminous efficiency, but the material durability is insufficient.

[0006] On the other hand, chalcogenide perovskites have characteristics of a large optical absorption coefficient and excellent durability. In addition, since the distribution curve of the absorption edge of chalcogenide perovskites is steep, excellent luminous performance can also be expected. For example, quantum dots using chalcogenide perovskites are disclosed in Patent Document 1.

[0007] Prior Art Documents

[0008] Patent Document

[0009] Patent Document 1: US Patent Application Publication No. 2019 / 0225883 Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] However, although the quantum dots of chalcogenide perovskite have excellent light absorption properties, on the other hand, the loss caused by the reabsorption of luminescence is also large. If the particle size is reduced to suppress this reabsorption loss, the absorbance decreases. That is, the absorbance and the reabsorption loss are in a relationship of mutual growth and decline.

[0012] The present invention has been completed in view of the above circumstances, and provides a color conversion particle that achieves high absorbance and high luminescence efficiency while suppressing the reabsorption loss of luminescence.

[0013] Means for Solving the Problems

[0014] The color conversion particle of one embodiment of the present invention includes a core and a shell that contains the core and absorbs excitation light, and the color conversion particle receives the irradiated excitation light and generates luminescence at the core or the interface between the core and the shell. The core is composed of chalcogenide perovskite, and the core and the shell have a band alignment that exhibits a Stokes shift.

[0015] Advantages of the Invention

[0016] According to the color conversion particle of the present invention, it is possible to achieve high absorbance and high luminescence efficiency while suppressing the reabsorption loss of luminescence. Brief Description of the Drawings

[0017] Figure 1 It is a schematic diagram showing a configuration example of the color conversion particle of the present embodiment.

[0018] Figure 2 It is a graph showing an example of the relationship between excitation energy and particle radius.

[0019] Figure 3 It is a graph showing an example of the relationship between excitation energy and particle radius based on the physical property values of BaZrS 3 It is a graph showing an example of the relationship between excitation energy and particle radius based on the physical property values of BaZrS.

[0020] Figure 4 It is a diagram showing an example of the band alignment of the core and the shell.

[0021] Figure 5 It is a diagram showing an example of the band alignment of the core and the shell.

[0022] Figure 6 It is a diagram showing an example of the band alignment of the core and the shell.

[0023] Figure 7 It is a diagram showing a modified example of the color conversion particles of the present embodiment.

[0024] Figure 8 It is a diagram showing a modified example of the color conversion particles of the present embodiment.

[0025] Figure 9 It is a diagram showing the energy band alignment of the core and the shell in the examples.

[0026] Figure 10 It is a diagram showing the results of the simulation of the examples.

[0027] Figure 11 It is a diagram showing BaZrS 3 and SrZrS 3 's light absorption coefficient and the distribution curves of the PL emission spectra of BaZrS 3 respectively.

[0028] Figure 12 It is a diagram showing the correspondence between the combination of the core and shell materials in the examples and comparative examples and the type of energy band alignment and the manifestation of the Stokes shift. Detailed implementation mode

[0029] Hereinafter, the embodiments will be described with reference to the drawings.

[0030] In the embodiments, for the sake of easy understanding of the description, the structures or elements other than the main part of the present invention are described in a simplified or omitted manner. In addition, in the drawings, the same reference numerals are assigned to the same elements. It should be noted that in the drawings, the shapes, sizes, etc. of the respective elements are schematically shown and do not represent the actual shapes, sizes, etc.

[0031] <Structure of color conversion particles>

[0032] Figure 1 (a) of is a schematic diagram showing a configuration example of the color conversion particles of the present embodiment.

[0033] The color conversion particles 10 are particles having a nanoscale overall shape and perform color conversion by absorbing the incident excitation light and re-emitting (luminescing) it in the form of light with different energies (wavelengths).

[0034] The color conversion particles 10 have a core 11 as a light-emitting part and a shell 12 as a light-absorbing part. The shell 12 contains one or more cores 11 inside it. And, a part or all of each core 11 is covered by the shell 12 from the outside, thereby constituting the color conversion particles 10.

[0035] In the color conversion particle 10, the core 11 and the shell 12 are separately provided, and a chalcogenide perovskite is used as the material of the core 11. Thereby, while achieving high absorbance of the excitation light and high luminescence performance of the core 11, the durability of the color conversion particle 10 is also improved. This will be described later.

[0036] In addition, in the core 11 and the shell 12, the energy E c of the lower end of the conduction band and the energy E v of the upper end of the valence band have a band alignment relationship that causes the Stokes shift to appear. The band alignment of the core 11 and the shell 12 will be described later.

[0037] Furthermore, by adjusting the band gaps of the core 11 and the shell 12, the shell 12 can be given the property of transmitting the light emitted by the core 11. Thereby, in the color conversion particle 10, the light generated in the core 11 can be suppressed from being reabsorbed by the shell 12.

[0038] <Core 11>

[0039] The core 11 is a luminescent particle composed of a semiconductor material that generates fluorescence with a target emission wavelength through excitation light. The core 11 as the luminescent particle generates an inter-electron energy level transition having an energy corresponding to the target emission wavelength.

[0040] (Material of the core)

[0041] The core 11 is composed of a chalcogenide perovskite.

[0042] The chalcogenide perovskite is a semiconductor formed by a perovskite crystal structure group containing a chalcogen element (S, Se, Te) at the X site, and also includes a substance in which a part of the X site is replaced by oxygen (O).

[0043] The above perovskite represents a group of substances having a cubic crystal structure with an octahedron of BX 3 shown by the chemical formula ABX 6 as the backbone, and can obtain a tetragonal crystal structure and an orthorhombic crystal structure by accompanying lattice distortion. In addition, in the same ABX 3 composition, multiple stable crystal structures have been revealed in the field of computational science. These crystal structures include structures ranging from those close to the perovskite structure to those significantly different. In addition, as derivative structures, there are layered perovskites of the Ruddlesden-Popper type and Dion-Jacobson type based on the perovskite structure, and crystal structures of double perovskites in which different elements are alternately arranged at the B site, etc.

[0044] In this specification, the above crystal structures are collectively referred to as the "perovskite crystal structure group".

[0045] The perovskite crystal structure group specifically includes substances having the following crystal structures.

[0046] Cubic perovskite, tetragonal perovskite, GdFeO 3 orthorhombic type, YScS 3 orthorhombic type, NH 4 CdCl 3 orthorhombic type, BaNiO 3 hexagonal type, FePS 3 monoclinic type, PbPS 3 monoclinic type, CeTmS 3 monoclinic type, Ruddlesden-Popper type layered perovskite, Dion-Jacobson type layered perovskite, double perovskite.

[0047] It should be noted that the crystal structure group of perovskite changes in crystal structure and electronic structure according to composition and synthesis conditions, and the optoelectronic properties and chemical characteristics change. Therefore, the composition and conditions are selected in such a way as to form a crystal structure suitable for the purpose.

[0048] For example, substances with cubic perovskite, tetragonal perovskite, GdFeO 3 orthorhombic perovskite, Ruddlesden-Popper type layered perovskite, and double perovskite structures have excellent optoelectronic properties and chemical characteristics. In addition, by setting it to the Dion-Jacobson type layered perovskite structure, the chemical stability can be further improved.

[0049] In particular, it is known that substances with the crystal structure of GdFeO 3 (A = Group 2, B = Group 4) shown orthorhombic perovskite have excellent optoelectronic properties represented by a high light absorption coefficient. 3

[0050] In addition, the chemical formula of chalcogenide perovskite can be represented by ABX 3 , A’ 2 A n-1 B n X 3n+1 , A”A”’B” 2 X 7 , A”A 2 B” 3 X 10 , A 2 BB’X 6 indicated.

[0051] In the above chemical formula, X represents a chalcogen element (S, Se, Te). A and A' represent Group 2 elements (Ca, Sr, Ba), A" represents Group 1 elements (Li, Na, K, Rb, Cs), A''' represents Group 3 elements (rare earth elements) and Bi. B and B' represent Group 4 elements (Ti, Zr, Hf), and B" represents Group 5 elements (V, Nb, Ta). Additionally, n is set as a positive integer. It should be noted that A and A', B and B' can be the same element. Moreover, A, A', A", A''', B, B', B", X respectively include elements formed by mixing the elements in their respective groups in any ratio.

[0052] As an example, the chalcogenide perovskite represented by the chemical formula ABX 3 contains the following substances. In the following examples, X is selected from (S, Se) which are the dominant materials among the chalcogen elements, A is selected from (Sr, Ba) which are the dominant materials among the Group 2 elements, and B is selected from (Zr, Hf) which are the dominant materials among the Group 4 elements.

[0053] SrZrS 3 、SrZrSe 3 、SrHfS 3 、SrHfSe 3 、BaZrS 3 、BaZrSe 3 、BaHfS 3 、BaHfSe 3 .

[0054] Additionally, as an example, the chalcogenide perovskite represented by the chemical formula A' 2 A n-1 B n X 3n+1 contains the following substances. X is selected from (S, Se) which are the dominant materials among the chalcogen elements, A and A' are selected from (Sr, Ba) which are the dominant materials among the Group 2 elements, and B is selected from (Zr, Hf) which are the dominant materials among the Group 4 elements.

[0055] Sr 2 Ba n-1 Zr n S 3n+1 、Sr 2 Ba n-1 Zr n Se 3n+1 、Sr n+1 Zr n S 3n+1 、Sr n+1 Zr n Se 3n+1 、Ba 2 Srn-1 Zr n S 3n+1 、Ba 2 Sr n-1 Zr n Se 3n+1 、Ba n+1 Zr n S 3n+1 、Ba n+1 Zr n Se 3n+1 、Sr 2 Ba n-1 Hf n S 3n+1 、Sr 2 Ba n-1 Hf n Se 3n+1 、Sr n+ 1 Hf n S 3n+1 、Sr n+1 Hf n Se 3n+1 、Ba 2 Sr n-1 Hf n S 3n+1 、Ba 2 Sr n-1 Hf n Se 3n+1 、Ba n+1 Hf n S 3n+1 、Ba n+1 Hf n Se 3n+1 。

[0056] These chalcogenide perovskites can also be represented by (Sr x Ba 1-x )(Zr y Hf 1-y )(S z Se 1-z ) 3 or (Sr x’ Ba 1-x’ ) 2 (Sr x Ba 1-x ) n-1 (Zr v Hf 1-y ) n (S z Se 1-z ) 3n+1 where x, x', y, and z are values greater than or equal to 0 and less than or equal to 1, respectively).

[0057] It should be noted that the above-mentioned advantageous materials among X, A, A', and B are materials with a band gap suitable for uses such as emitting visible light in light-emitting devices, display devices, lighting devices, etc. when applied to the color conversion particles 10.

[0058] Here, as the material for the core emitting red light, for example, BaZrS can be cited. 3 As the material for the core emitting green light, for example, SrHfS can be cited. 3 As the material for the core emitting blue light, for example, BaZr(O, S) can be cited. 3

[0059] In chalcogenide perovskites, by partially substituting the constituent elements with elements of the same or different groups, the carrier concentration or crystal structure can be controlled, and other physical and chemical properties can be adjusted. For example, the Group 1 element can be substituted with Groups 1 and 2, the Group 2 element can be substituted with Groups 1, 2, and 3, the Group 3 element can be substituted with Groups 2, 3, and 4, the Group 4 element can be substituted with Groups 3, 4, and 5, and the Group 16 element can be substituted with Groups 15, 16, and 17.

[0060] As the advantages of chalcogenide perovskites, the following advantages can be cited.

[0061] Chalcogenide perovskites have the characteristics of a large optical absorption coefficient and excellent luminescence properties (luminescence efficiency, full width at half maximum). In addition, the distribution curve of the optical absorption coefficient of chalcogenide perovskites rises steeply at the band edge. Therefore, chalcogenide perovskites have the characteristic of high absorbance near the band gap edge.

[0062] Therefore, the core 11 of chalcogenide perovskites has a high absorbance and can effectively absorb the excitation light.

[0063] In addition, chalcogenide perovskites have high chemical stability and excellent durability against external environments and stimuli such as the atmosphere, moisture, heat, and light. Therefore, the core 11 of chalcogenide perovskites has high durability and can inhibit the deterioration of the core 11.

[0064] Furthermore, chalcogenide perovskites are highly safe because they do not contain toxic elements, and their raw material costs are low because they do not contain rare metals, which is also advantageous in this regard.

[0065] (Size of the core)

[0066] Next, after explaining the quantum dots as a premise, the size of the core will be explained.

[0067] ​When a semiconductor is used in a luminescent particle, luminescence basically uses fluorescence emitted when electrons excited to the conduction band recombine with holes in the valence band. Therefore, the luminescence wavelength in the luminescent particle corresponds to the bandgap energy E of the bulk. g，bulk .

[0068] If the particle size of the luminescent particle becomes smaller and the quantum size effect caused by the confinement of electrons becomes significantly apparent, the energy levels of the electrons become discrete. In this case, the energy (bandgap) E of the lowest excited state ex is greater than E g，bulk , and depends on the particle size. That is, if the particle size of the luminescent particle becomes smaller, the luminescence wavelength shifts to the shorter wavelength side compared to the bulk state, and the luminescence wavelength varies according to the particle size. By utilizing this property, the luminescence wavelength of the luminescent particle can be controlled.

[0069] Specifically, E of a luminescent particle with a radius r ex is given by the following formula. Note that μ represents the reduced exciton mass, E b，ex represents the exciton binding energy, and r B represents the exciton Bohr radius.

[0070]

Mathematical formula 1

[0071]

[0072] μ, E b，ex , r B are respectively given by the following formulas, where ε is the dielectric constant of the luminescent particle. Note that m * e is the effective mass of the electron, and m * h is the effective mass of the hole.

[0073]

Mathematical formula 2

[0074]

[0075]

[0076]

[0077] Figure 2 is a graph showing the dependence of E ex on r when μ = 0.1 and ε = 10. Figure 2 The vertical axis of ex represents E g，bulk / E B The horizontal axis of B . As the radius r of the luminescent particle becomes smaller and approaches r ex , E g，bulkThe value ranges from E g，bulk and gradually increases. Moreover, if r is r B or less, the value of E ex significantly increases (quantum size effect).

[0078] Utilizing the characteristics of the above-mentioned quantum size effect, based on r B determined by the above formula, luminescent particles with a particle size range where the emission wavelength depends on the particle size are called "quantum dots". On the other hand, luminescent particles with a particle size range where the emission wavelength hardly depends on the particle size are called "non-quantum dots".

[0079] It should be noted that the particle size showing the quantum size effect varies according to the parameters of μ and ε. As a typical semiconductor, if it is assumed that μ = 0.1 and ε = 10, then r = 3r B or so becomes the boundary of the particle size (radius) showing the quantum size effect. It should be noted that in Figure 2 this boundary is represented by a dashed line.

[0080] As described above, the particle size showing the quantum size effect in luminescent particles is basically characterized by the relationship with the exciton Bohr radius r B , but the manifestation of the quantum size effect is also related to the dielectric constant of the material and the effective mass of electron holes, and the change in the value of E ex is also continuous. Therefore, it is actually difficult to uniquely describe the boundary between quantum dots and non-quantum dots with the particle size and other physical property values.

[0081] Figure 3 is a graph showing the particle radius dependence of E 3 calculated using typical physical property values (m e * = 0.3m 0 , m h * = 0.5m 0 , ε = 6ε 0 , E g，bulk = 1.93 eV) of the typical chalcogenide perovskite material BaZrS ex . The above m 0 is the mass of an electron. Figure 3 The vertical axis of Figure 3 represents the lowest excitation energy (eV),

[0082] and the horizontal axis of Figure 3 represents the particle radius (nm). 3 In the example of BaZrS 3In the example, particles with a particle size of 15 nm or less are considered quantum dots, and particles with a particle size exceeding 15 nm are considered non-quantum dots.

[0083] The core 11 of the present embodiment can be any one of the above-mentioned quantum dots and non-quantum dots.

[0084] When the core 11 is a quantum dot, it has the advantage of being able to control the emission wavelength (color) by changing the particle size of the same substance. In addition, in the case of a quantum dot, the core 11 has high luminous efficiency and a narrow peak.

[0085] However, in order to make the emission wavelength (color) consistent, strict particle size control is required, and the manufacture of quantum dots requires a high level of manufacturing technology. In addition, since quantum dots are tiny particles, they lack chemical stability and are prone to aggregation, regrowth, and decomposition, so the surface needs to be protected. In addition, the electronic state of quantum dots is discrete, so the density of states in the valence band and conduction band is small, and the light absorption coefficient becomes smaller compared to the bulk.

[0086] On the other hand, when the core 11 is a non-quantum dot, that is, when relatively large particles are used and the bulk luminescence is utilized without showing the quantum size effect, the problems of stability and light absorption are alleviated. However, in a non-quantum dot, the emission wavelength of the core 11 is determined by E g，bulk Therefore, in order to adjust the emission wavelength, it is necessary to change E by changing the composition and crystal structure. g，bulk change.

[0087] As described above, both quantum dots and non-quantum dots have their own advantages and disadvantages. Therefore, as the composition of the core 11, an appropriate composition can be selected from quantum dots and non-quantum dots according to the situation and application. In addition, the size that generates the quantum size effect varies depending on the material, so the particle size of the core 11 is appropriately set according to the physical properties of the material, etc.

[0088] On the other hand, in order to suppress the reabsorption of the core 11, it is preferable that the particle size of the core 11 is small. The optical coefficient of BaZrS shown in the literature "Y. Nishigaki et al., Sol. RRL 1900555 (2020)." is used to calculate the proportion of the light reabsorbed by the core 11. For example, when the particle size of BaZrS 3 is 200 nm, it absorbs 10% of the red light with a wavelength of 630 nm generated by the core of another BaZrS 3 configured nearby. Therefore, the particle size of the core 11 is preferably 200 nm or less. 3 configured nearby. Therefore, the particle size of the core 11 is preferably 200 nm or less.

[0089] In addition, if the particle diameter of the core 11 is set to 50 nm or less under the above conditions, the reabsorption of red light with a wavelength of 630 nm becomes 3%. If the particle diameter of the core 11 is set to 25 nm or less, the reabsorption of red light with a wavelength of 630 nm can be suppressed to 2% or less. Therefore, the particle diameter of the core 11 is preferably 50 nm or less, more preferably 25 nm or less.

[0090] In addition, as the size of the particle diameter at which the core 11 can stably exist, it is preferably 1 nm or more.

[0091] Accordingly, the particle diameter of the core 11 is preferably 1 nm or more and 200 nm or less.

[0092] <Shell 12>

[0093] (Material of the shell)

[0094] The shell 12 is composed of a semiconductor material that absorbs the target excitation light wavelength and generates excited carriers.

[0095] As the material of the shell 12, for example, II-VI group semiconductors, III-V group semiconductors, I-III-VI group semiconductors, I-II-IV-VI group semiconductors, IV-VI group semiconductors, halide perovskite semiconductors, oxide perovskites, organic-inorganic perovskites, Si, carbon materials, or their mixed crystal compounds, etc. can be used.

[0096] In the color conversion particles, the light emitted at the interface of the core or the core and the shell passes through the shell and is extracted to the outside. Therefore, the shell needs to transmit the emitted light. If absorption of the emitted light occurs in the shell, the luminous efficiency of the color conversion particles decreases corresponding to the degree of absorption. Therefore, the band gap of the shell is preferably equal to or greater than the energy of the emitted light.

[0097] In addition, chalcogenide perovskite can also be used as the material of the shell 12. By using chalcogenide perovskite having an excellent light absorption coefficient, the absorbance of the shell 12 can be increased. In addition, for the shell 12 of chalcogenide perovskite, from the viewpoints of the affinity with the constituent elements of the core and the matching of the crystal structure and lattice constant, the defects at the interface between the core 11 and the shell 12 are reduced rather than the non-radiative recombination is reduced, so higher luminous efficiency of the core 11 can be expected.

[0098] As an example, in the case of applying chalcogenide perovskite to the material of the shell 12, a substance different from the material of the core 11 can be selected from the following listed substances.

[0099] SrZrS 3 、SrZrSe 3 、SrHfS 3 、SrHfSe 3 、BaZrS3 , BaZrSe 3 , BaHfS 3 , BaHfSe 3 , Sr 2 , Ba n- 1 , Zr n , S 3n+1 , Sr 2 , Ba n-1 , Zr n , Se 3n+1 , Sr n+1 , Zr n , S 3n+1 , Sr n+1 , Zr n , Se 3n+1 , Ba 2 , Sr n-1 , Zr n , S 3n+1 , Ba 2 , Sr n-1 , Zr n , Se 3n+1 , Ba n+1 , Zr n , S 3n+1 , Ba n+1 , Zr n , Se 3n+1 , Sr 2 , Ba n-1 , Hf n , S 3n+1 , Sr 2 , Ba n-1 , Hf n , Se 3n+1 , Sr n+1 , Hf n , S 3n+1 , Sr n+1 , HfnSe 3n+1 , Ba 2 , Sr n-1 , Hf n , S 3n+1 , Ba 2 , Sr n-1 , Hf n , Se 3n+1 , Ba n+1 , Hf n , S 3n+1 , Ba n+1 , Hf n , Se 3n+1

[0100] The chalcogenide perovskites applicable to shell 12 can be similarly formed from (Sr x , Ba1-x )(Zr y Hf 1-y )(S z Se 1-z ) 3 or (Sr x’ Ba 1-x’ ) 2 (Sr x Ba 1-x ) n-1 (Zr y Hf 1-y ) n (S z Se 1-z ) 3n+1 wherein x, x', y, and z are each a value of 0 or more and 1 or less).

[0101] These substances are advantageous materials in terms of having a band gap suitable for use in emitting visible light in light-emitting devices, display devices, lighting devices, etc. when applied to the shell 12 of the color conversion particles 10.

[0102] (Thickness of the shell)

[0103] In addition, the lower limit and upper limit of the thickness of the shell 12 are defined based on the following viewpoints.

[0104] First, it is required that the shell 12 as the light absorption part has a thickness capable of sufficiently absorbing the excitation light.

[0105] As the use of the color conversion particles 10, it is generally envisioned to use a large amount of color conversion particles 10 in a film, coating film, resin, etc. as a color conversion material. In this case, the shell 12 is preferably set to a thickness having an excitation light absorption rate of at least 0.1% or more. In addition, as long as each shell 12 has a thickness of at least 2 nm, sufficient absorbance can be achieved for the color conversion material as a whole using a plurality of color conversion particles.

[0106] Second, if the thickness of the shell 12 is too thick, the photoexcited carriers recombine and deactivate before reaching the core 11, resulting in a decrease in luminous efficiency.

[0107] The diffusion length of photoexcited carriers or excitons varies depending on the material, but is roughly several tens of nm to several hundreds of nm except in the case of very high-quality single crystals.

[0108] In addition, if the particle size of the color conversion particles 10 becomes too large, when a large amount of color conversion particles 10 are contained in a film, coating film, resin, etc., the gaps between the particles become large, and the density of the color conversion particles 10 decreases. In the above case, as a result, the absorbance of the wavelength conversion material using the color conversion particles 10 decreases.

[0109] In addition, in the case of coating an ink in which the color conversion particles 10 are dispersed in a solvent by, for example, an inkjet method, if the particle size of the color conversion particles 10 is too large, it may cause nozzle clogging. In other coating methods, the large particle size of the color conversion particles 10 can also pose a problem in the process.

[0110] For the reasons described above, the particle size of the color conversion particles 10 is preferably 1000 nm or less. At this time, the thickness of the shell 12 serving as the light absorption part is preferably 500 nm or less.

[0111] From the viewpoint of suppressing the recombination of photoexcited carriers, if the shell 12 can sufficiently absorb the excitation light, it is preferable that the thickness of the shell 12 is thinner. For example, the thickness of the shell 12 is preferably 50 nm or less, more preferably 30 nm or less, and still more preferably 10 nm or less.

[0112] <Band alignment between the core 11 and the shell 12>

[0113] As described above, in the core 11 and the shell 12, the energy E at the lower end of the conduction band c and the energy E at the upper end of the valence band v The band alignment forms a relationship that causes the Stokes shift to appear.

[0114] The Stokes shift originally refers to the energy difference between the energy state of an electron excited by light and the electron state when the electron emits energy and luminesces in a single substance, and is observed as the difference in the maximum energy positions of the absorption spectrum and the emission spectrum.

[0115] For the heterostructure nanoparticles such as the color conversion particles 10 of the present embodiment, by designing an appropriate band alignment at the heterointerface, an "apparent Stokes shift", that is, the energy difference between the absorption spectrum edge and the emission spectrum peak, can be generated. In this specification, the apparent Stokes shift generated in the heterostructure nanoparticles is sometimes simply referred to as the Stokes shift.

[0116] Figure 4 , Figure 5 , Figure 6 Examples of the band alignment between the core 11 and the shell 12 are shown.

[0117] In Figure 4 , Figure 5 , Figure 6 In each of the figures, the upward direction represents the direction of increasing energy, the central rectangle represents the band gap E of the core 11 g_core , and the rectangles on both sides represent the band gap E of the shell 12 g_shell . The upper side of the central rectangle represents the energy E at the lower end of the conduction band of the core 11 c_core , and the lower side of the central rectangle represents the energy E at the upper end of the valence band of the core 11 v_coreThe upper sides of the rectangles on both sides represent the energy E of the lower end of the conduction band of the shell 12 c_shell and the bottom sides of the rectangles on both sides represent the energy E of the upper end of the valence band of the shell 12 v_shell .

[0118] In addition, in Figure 4 , Figure 5 , Figure 6 , in each figure, the curve depicted on the upper side of the rectangle represents the distribution of electrons, and the curve depicted on the bottom side of the rectangle represents the distribution of holes. In addition, the downward arrow in the figure represents the energy difference in the light emission process, and the upward arrow in the figure represents the energy difference in the light absorption (excitation) process. When the energy difference in the light absorption process is greater than the energy difference in the light emission process, a Stokes shift appears.

[0119] In Figure 4 , for (a)-(e), the band gap E g_shell of the shell 12 is greater than the band gap E g_core of the core 11 g_shell (E g_core > E g_shell ). On the other hand, in Figure 5 , for (a)-(e), the band gap E g_core of the shell 12 is smaller than the band gap E g_shell of the core 11 g_core (E g_shell < E g_core ). In addition, in Figure 6 , for (a)-(c), the band gap E g_shell of the shell 12 is equal to the band gap E g_core of the core 11 c_core (E c_shell = E v_core ). It should be noted that the magnitude relationship between E v_shell and E Figure 4 , Figure 5 , Figure 6 is marked separately in each figure.

[0120] The Stokes shift appears in the band alignments (Type I, Quasi-Type II, and Type II) shown in (a)-(e) of Figure 4 , (a), (e) of Figure 5 , and (a), (c) of Figure 6 . Therefore, the color conversion particles of this embodiment have Figure 4 , for (a)-(e) of Figure 5 , (a), (e) of Figure 6 , and any one of the band alignments in (a), (c) of c_shellThe energy E higher than the lower end of the conduction band of the core 11 c_core 、or the energy E higher than the upper end of the valence band of the shell 12 v_shell lower than the upper end of the valence band of the core 11 v_core At least any one of the conditions (i.e., E c_shell >E c_core 、E v_shell <E v_core Any one of them, or E c_shell >E c_core and E v_shell <E v_core ).

[0121] Figure 4 For the energy band alignments (Type I and Quasi-Type II) of (b), (c), and (d) of Figure 4 , the lower end of the conduction band of the shell 12 satisfies that the energy E c_shell is the energy E of the lower end of the conduction band of the core 11 c_core or higher and the upper end of the valence band of the shell 12 satisfies that the energy E v_shell is the energy E of the upper end of the valence band of the core 11 v_core or lower (i.e., when E g_shell >E g_core , E c_shell ≥E c_core and E v_shell ≤E v_core ).

[0122] In Figure 4 In the case of Type I shown in (c) of Figure 4 , electrons and holes are confined in the core 11 and recombination (core luminescence) occurs within the core 11. In Type I, holes and electrons are locally present in the core 11, so the overlap of the wave functions is large and the luminescence efficiency is high. Therefore, as the energy band alignment between the core 11 and the shell 12, the Type I structure is most preferred. As Figure 4 For the materials of the core 11 and the shell 12 of Type I shown in (c) of Figure 4 , for example, the core 11 can be BaZrS 3 and the shell 12 can be SrZrS 3 combination.

[0123] Figure 4 In Quasi-Type II shown in (b) and (d) of Figure 4 (where E g_shell >E g_core ), one of the carriers, holes or electrons, extends to the shell, so the luminescence efficiency is lower than that of Type I. However, in Figure 4 In (b) and (d) of Figure 4 , even so, the other carrier is locally present in the core, so the luminescence efficiency is relatively high and it is preferred after Type I. As Figure 4For the materials of the core 11 and the shell 12 of Quasi-Type II shown in (b) and (d), examples include Figure 4 in (b) of 3 , the core 11 is BaHfS 3 , and the shell 12 is CaZrS

[0124] In addition, in Figure 4 (a), (e), Figure 5 (a), (e), Figure 6 (a), (c) of the band alignment (Type II), electrons and holes are separated in the core 11 and the shell 12. Therefore, compared with Type I, luminescence based on interband recombination is less likely to occur. However, in Type II, recombination (interface luminescence) may occur at the interface between the core 11 and the shell 12, resulting in an energy difference smaller than the E g of the shell 12, so a Stokes shift is exhibited.

[0125] In the case of Type II, it is the luminescence at the interface between the core 11 and the shell 12. Therefore, the overlap of wave functions is small, and the luminescence efficiency is lower than that of Type I. In addition, it is considered that non-luminescent recombination via interface defects sometimes occurs in interface recombination, so the luminescence efficiency is also reduced in this regard.

[0126] However, in the band alignment of Type II, it is advantageous in terms of enabling a wide range of luminescence wavelengths, and applications in near-infrared luminescent materials etc. are expected. As Figure 4 (a), (e), Figure 5 (a), (e), Figure 6 (a), (c) of the materials of the core 11 and the shell 12 of Type II shown, examples include Figure 4 in (a) of 3 , the core 11 is BaZrS 3 , and the shell 12 is CaZrS

[0127] In addition, as shown in Figure 4 (a)-(e), if the band gap E g_shell of the shell 12 is made larger than the band gap E g_core of the core 11 (E g_shell >E g_core ), then the light emitted from the core 11 is hardly absorbed by the shell 12 and is emitted to the outside. Thus, the reabsorption loss in the shell 12 is suppressed, and the luminescence efficiency of the color conversion particle 10 can be further improved.

[0128] In Figure 6 (a), (c), the band gap E g_shell of the shell 12 is equal to the band gap E g_core of the core 11 (Eg_shell = E g_cpre ). Therefore, in Figure 6 for cases (a) and (c), compared with Figure 4 cases (a)-(e) of (E g_shell > E g_core ), the light emitted from the core 11 is more likely to be reabsorbed by the shell 12, and the reabsorption loss increases. Therefore, the luminous efficiency of the color conversion particle 10 becomes lower. It should be noted that if the band gap E of the shell 12 is like Figure 5 in cases (a) and (e) such that g_shell the band gap E of the shell 12 is less than the band gap E of the core 11 g_core (E g_shell < E g_core ), and this case is compared with cases (a) and (c) of Figure 6 , then in cases (a) and (c) of Figure 6 , less light is reabsorbed by the shell 12, the reabsorption loss is suppressed, and therefore the luminous efficiency of the color conversion particle 10 can be improved.

[0129] It should be noted that the color conversion particle 10 can take various states according to the combination of the material of the core 11 and the material of the shell 12. The materials of the core 11 and the shell 12 exemplified above are sulfides, but they can also be selenides or solid solutions. If they are also included, various states can be achieved, and there are combinations of the materials of the core 11 and the shell 12 that exhibit excellent luminous characteristics.

[0130] <Manufacturing method of the color conversion particle 10>

[0131] Next, the manufacturing method of the color conversion particle 10 will be described. The color conversion particle 10 is manufactured by performing the synthesis process of the shell 12 after the synthesis process of the core 11.

[0132] (Synthesis process of the core 11)

[0133] In the synthesis process of the core 11, the core 11 as a nano-luminescent particle is formed from a chalcogenide perovskite. In this process, the core 11 can be synthesized by reacting precursor compounds in a solution, or by mixing and heating precursor powders in an inert atmosphere or in the air, or by mixing and heating metal precursor powders in an inert atmosphere and reacting them with a chalcogen precursor gas to synthesize the core 11.

[0134] When the core 11 is synthesized by reacting precursor compounds in a solution, for example, the thermal injection method, the temperature-raising method, the solvothermal method, the hydrothermal method, the CHM (composite-hydroxide-mediated) method, the continuous flow process synthesis method, etc. can be applied.

[0135] As an example, the case of the core 11 of a chalcogenide perovskite ABX3 in which A and B contain group II and group IV elements respectively synthesized by a hot injection method will be described.

[0136] In this case, a first solution and a second solution are prepared. The first solution contains a precursor compound containing a group II element, a precursor compound containing a group IV element, and a solvent, and the second solution contains a precursor compound containing a chalcogen element and a solvent. Then, for the above-mentioned first solution, the second solution is introduced into a reaction vessel at a temperature in the range of 130°C to 400°C and maintained in the reaction vessel at the above temperature for 1 second to 100 hours to cause a reaction. Thus, the core 11 of the target chalcogenide perovskite compound is synthesized. After the reaction is completed, it is washed with an organic solvent or water, and then the target product is recovered.

[0137] As the above-mentioned precursor compound containing a group II element, the following precursor compounds can be mentioned.

[0138] Metal powder, metal alkoxide, metal carboxylate, metal nitrate, metal perchlorate, metal sulfate, metal acetylacetonate, metal halide, metal hydroxide, metal halide, and combinations thereof.

[0139] As the above-mentioned precursor compound containing a group IV element, the following precursor compounds can be mentioned.

[0140] Metal powder, metal alkoxide, metal carboxylate, metal nitrate, metal perchlorate, metal sulfate, metal acetylacetonate, metal halide, metal hydroxide, metal halide, and combinations thereof.

[0141] As the above-mentioned precursor compound containing a chalcogen element, the following compounds can be mentioned.

[0142] Metal sulfide (including selenide or telluride);

[0143] Carbon disulfide (including selenide or telluride);

[0144] Chalcogen hydrides such as hydrogen sulfide, hydrogen selenide, and hydrogen telluride;

[0145] Thiol compounds (including selenide or telluride);

[0146] Phosphine compounds such as trioctylphosphine sulfide (including selenide or telluride);

[0147] Thiourea (including selenide or telluride);

[0148] Sulfur, selenium, tellurium,

[0149] Or substances obtained by dispersing these compounds in solvents such as amines, acids, and hydrocarbons, and combinations thereof.

[0150] As the above solvent, the following solvents can be cited.

[0151] Normally used organic solvents or water, wherein the organic solvent contains at least one of the following compounds:

[0152] Primary amines, secondary amines, and tertiary amines having organic groups such as hydrocarbon groups;

[0153] Aromatic hydrocarbons;

[0154] Nitrogen-containing heterocyclic compounds, oxygen-containing heterocyclic compounds, sulfur-containing heterocyclic compounds, selenium-containing heterocyclic compounds, tellurium-containing heterocyclic compounds;

[0155] Aliphatic hydrocarbons;

[0156] Phosphine compounds having organic groups such as hydrocarbon groups;

[0157] Phosphine oxide compounds having organic groups such as hydrocarbon groups;

[0158] Compounds having alcohol, aldehyde, carboxylic acid or their thio groups, seleno groups, telluro groups.

[0159] In addition, combinations of these solvents.

[0160] The heating of the above solution includes reacting a chalcogen precursor to form hydrogen chalcogenide. In addition, the reaction of the above solution includes synthesis under an inert atmosphere. Further, the reaction of the above solution can use a microreactor to synthesize the target by a continuous flow process.

[0161] In addition, as an example, the case of applying the temperature-raising method to synthesize the core 11 of chalcogenide perovskite is described.

[0162] In this case, a solution containing a precursor compound containing a Group II element, a precursor compound containing a Group IV element, a precursor compound containing a chalcogen element, and a solvent is prepared. Then, the above solution is heated from a room temperature state to a temperature in the range of 130 °C to 400 °C in a reaction vessel, and the reaction is carried out by maintaining the temperature in the reaction vessel at the above temperature for 0 hours to 100 hours. Thus, the core 11 of the target chalcogenide perovskite compound is synthesized. After the reaction is completed, it is washed with an organic solvent or water, and then the target is recovered.

[0163] Regarding the above precursor compound containing a Group II element, precursor compound containing a Group IV element, precursor compound containing a chalcogen element, and solvent, it is the same as in the case of the thermal injection method.

[0164] Heating of the above solution includes causing a chalcogen precursor to react to form hydrogen chalcogenide. Additionally, during heating, the reaction vessel is sometimes pressurized (solvothermal, hydrothermal). Furthermore, the reaction of the above solution can use a micro-reaction vessel to synthesize the target in a continuous flow process.

[0165] Additionally, as an example, the case of applying the CHM method to synthesize the core 11 of chalcogenide perovskite is described.

[0166] In this case, a precursor compound containing a Group II element, a precursor compound containing a Group IV element, a precursor compound containing a chalcogen element, sodium hydroxide, and potassium hydroxide are heated in a reaction vessel from a room temperature state to a temperature in the range of 130 °C to 400 °C, and held at the above temperature in the reaction vessel for 0 hours to 200 hours to cause a reaction. Thereby, the core 11 of the target chalcogenide perovskite compound is synthesized. After the reaction is completed, it is washed with an organic solvent or water, and then the target is recovered.

[0167] Regarding the above precursor compound containing a Group II element, the precursor compound containing a Group IV element, and the precursor compound containing a chalcogen element, it is the same as in the case of the thermal injection method.

[0168] In the CHM method, sometimes no solvent is used, or some water is added. In the CHM method, a mixture obtained by mixing sodium hydroxide and potassium hydroxide at a ratio of 51.5:48.5 is dissolved at 165 °C to obtain a solution, and this solution functions as a solvent. Additionally, during heating, the reaction vessel is sometimes pressurized. Furthermore, the reaction of the above solution can use a micro-reaction vessel to synthesize the target by a continuous flow process.

[0169] Additionally, as an example, the case of applying the solid-phase synthesis method to synthesize the core 11 of chalcogenide perovskite is described.

[0170] In this case, in the same manner as the conventional solid-phase synthesis method, a precursor compound containing a Group II element, a precursor compound containing a Group IV element, and a precursor compound containing a chalcogen element are heated in a reaction vessel from a room temperature state to a temperature in the range of 400 °C to 1300 °C, and held at the above temperature in the reaction vessel for 0 hours to 200 hours to cause a reaction. Thereby, the core 11 of the target chalcogenide perovskite compound is synthesized.

[0171] Regarding the above precursor compound containing a Group II element, the precursor compound containing a Group IV element, and the precursor compound containing a chalcogen element, it is the same as in the case of the thermal injection method. Additionally, the above synthesis includes synthesis in an inert atmosphere or an air atmosphere.

[0172] (Synthesis process of the shell 12)

[0173] In the synthesis process of the shell 12, the shell 12 is synthesized on the surface of the core 11 obtained in the above process. For example, a shell material can be vapor-deposited on the surface of the core 11 by a vapor deposition method such as ALD method or CVD method, so as to synthesize the color conversion particles 10 having a core-shell structure. It should be noted that as a method for synthesizing the shell, the shell 12 can also be generated, for example, by vapor synthesis based on drum sputtering.

[0174] In addition, in the synthesis of the shell 12, a one-pot synthesis method or a thermal injection method can also be applied. In this case, the nano-luminescent particles serving as the core 11 and the precursor of the shell material are mixed in a solvent. Thereby, the color conversion particles 10 having a core-shell structure in which the surface of the core 11 is coated with the shell material are synthesized. It should be noted that the one-pot synthesis method and the thermal injection method can also be applied to the case of forming the shell 12 of chalcogenide perovskite.

[0175] <External structure of the color conversion particles 10>

[0176] In addition, as Figure 1 shown in (b) of

[0177] (Outer shell 13)

[0178] The outer shell 13 is a protective layer that covers the semiconductor particles formed by the core 11 and the shell 12 from the outside. The outer shell 13 is provided to further improve the durability of the color conversion particles 10 by protecting the semiconductor particles from chemical interaction with the outside while suppressing the deterioration of the semiconductor particles caused by contact with oxygen. In addition, the outer shell 13 has the property of transmitting the target excitation light and the light emitted by the core 11.

[0179] The outer shell 13 is formed of a chemically stable substance such as silica, glass, oxide insulator, resin, etc. by a known method.

[0180] For example, in the case where the outer shell 13 is formed of a metal oxide, silica, zirconia, titanium oxide, alumina, etc. can be used as materials. The outer shell 13 containing a metal oxide can be formed, for example, by a method of forming an inorganic oxide by using a thermal curing reaction using the sol-gel method.

[0181] In addition, the outer shell 13 can be a layer containing a resin or a polysilazane modified body, etc. Polysilazane is a polymer having a silicon-nitrogen bond and contains SiO formed by Si-N, Si-H, N-H, etc. 2 、Si 3 N 4 and an intermediate solid solution SiO x N yA ceramic precursor inorganic polymer or the like. In addition, when the outer shell 13 is formed of a resin, from the viewpoint of ease of manufacture, it is preferably formed of a water-soluble resin such as a polyvinyl alcohol-based resin.

[0182] It should be noted that the outer shell 13 may also be a multilayer structure having both a layer containing a metal oxide and a layer containing a resin or a polysilazane modified body or the like.

[0183] (Ligand 14)

[0184] The ligand 14 is an organic modifying molecule that surface-modifies the color conversion particles 10 and is arranged to bond to the outer surface of the color conversion particles 10 or to coat the color conversion particles 10.

[0185] The ligand 14 has the following functions: it easily isolates the color conversion particles 10 from each other to improve the dispersibility, and prevents regrowth, destruction, etc. caused by the contact of the color conversion particles 10 with each other. In addition, the ligand 14 also has the function of suppressing surface defects of the shell 12 and improving the luminous efficiency by capping the dangling bonds.

[0186] As the modifying organic molecule of the ligand 14, a modifying organic molecule having a structure with a nitrogen-containing functional group, a sulfur-containing functional group, an acidic group, an amide group, a phosphine group, a phosphine oxide group, a hydroxyl group, a straight-chain alkyl group, a carboxyl group, a phosphonyl group, a sulfo group, an amine group, etc. can be used. As such a modifying organic molecule, for example, sodium hexametaphosphate, sodium laurate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, triethanolamine lauryl sulfate, lauryl diethanolamide, dodecyltrimethylammonium chloride, trioctylphosphine, trioctylphosphine oxide, etc. can be cited.

[0187] In addition, as the modifying organic molecule of the ligand 14, a compound having a hydrophilic group and a hydrophobic group in the molecule is preferably used. Thereby, the color conversion particles 10 can be coated with the ligand 14 by both chemical bonding such as coordination bonding through a heteroatom and bonding based on physical adsorption. As such a modifying organic molecule, an amine, which is a compound having a non-polar hydrocarbon terminal as a hydrophobic group and an amino group as a hydrophilic group, can be cited. When the hydrophilic group of the modifying organic molecule is an amine, the amine can bond firmly to the metal element.

[0188] In addition, the modifying organic molecule of the ligand 14 preferably has a heteroatom. By making the modifying organic molecule have a heteroatom, an electrode polarity is generated between the heteroatom and the carbon atom, and the modifying organic molecule can be firmly bonded to the surface on the outer surface of the color conversion particles. Here, the "heteroatom" refers to all atoms other than hydrogen atoms and carbon atoms.

[0189] <Modified examples of the color conversion particles>

[0190] Next, refer to Figure 7 、 Figure 8A modified example of the color conversion particle 10 will be described. It should be noted that in the schematic diagram of the color conversion particle 10 shown in Figure 7 , Figure 8 , only the core 11 and the shell 12 are shown unless otherwise specified. However, these color conversion particles 10 may also have an outer shell 13 and a ligand 14 in the same manner as the example of Figure 1 (b).

[0191] For example, as shown in Figure 7 (a), the shell 12 of the color conversion particle 10 does not necessarily cover the entire core 11, and a part of the core 11 may be exposed to the outside.

[0192] For example, as shown in Figure 7 (b), the color conversion particle 10 may have a structure in which a plurality of shells 12 are laminated on the outside of one core 11. By using materials with different compositions, crystal structures, etc. as the materials for the respective shells 12, the light absorption characteristics and light emission characteristics of the entire color conversion particle 10 can be adjusted. In the example of Figure 7 (b), an example in which two layers of shells 12a and 12b are laminated on the core 11 is shown, but the shell 12 of the color conversion particle 10 may also have three or more layers.

[0193] Figure 7 The color conversion particle 10 having a plurality of shells 12a and 12b shown in

[0194] (b) can be formed by heating a solution containing semiconductor particles having a shell 12a formed on the core 11 and other shell precursors. Figure 7 (c), the color conversion particle 10 may have a structure in which a plurality of cores 11 are included in the shell 12. If a plurality of cores 11 are included in the shell 12, the thickness of the effective shell 12 in the color conversion particle 10 increases, and the durability of the color conversion particle 10 can be improved. In addition, by using materials with different compositions, crystal structures, etc. in each core 11, the light absorption characteristics and light emission characteristics of the entire color conversion particle 10 can be adjusted.

[0195] In the example of Figure 7 (c), a structure in which three cores 11 are included in the shell 12 is shown, but the number of cores 11 included in the shell 12 can be appropriately changed. In addition, in the color conversion particle 10 having a plurality of cores 11, any one of the cores 11 may be partially exposed to the outside of the shell 12.

[0196] In addition, the color conversion particle 10 may have a structure in which a plurality of cores 11 are included in the shell 12 and the shell 12 has a plurality of layers. For example, as shown in Figure 7 (d), the outside of the shell 12a including a plurality of cores 11 may be further covered with a shell 12b. It should be noted that it is also possible to Figure 7On the outer side of the shell 12b of (d), a further shell is laminated.

[0197] For example, as Figure 7 shown in (e), it is also possible to coat and integrate a plurality of nuclei 11 each coated with a shell 12a with a shell 12b to form the color conversion particles 10. It should be noted that, in the example of Figure 7 (e), the shell 12a may also contain a plurality of nuclei 11 respectively.

[0198] In addition, the nucleus 11 of the color conversion particle 10 may also contain an optical absorption material 17 made of the same kind of material as the shell 12. For example, as Figure 7 shown in (f), it may also be configured such that the outer side of the optical absorption material 17 is coated with the nucleus 11. It should be noted that the material of the optical absorption material 17 may be, for example, a material that can be selected as the material of the shell 12, and the shell 12 covering the nucleus 11 and the optical absorption material 17 may not be made of the same material.

[0199] As described above, in the structure of the laminated nucleus having the optical absorption material 17 inside, the optical absorption material 17 (the same kind of material as the shell 12) located inside the nucleus 11 can be used to absorb the excitation light transmitted through the outer shell 12, thereby improving the excitation light absorption rate. In addition, in the structure of the laminated nucleus having the optical absorption material 17 inside, by effectively enclosing photoexcited carriers in the narrow region of the nucleus 11 sandwiched by the material of the shell 12, the luminous efficiency can be improved.

[0200] In addition, the energy band alignment between the optical absorption material 17 and the nucleus 11 is preferably Type I. In addition, the energy band alignment between the nucleus 11 and the shell 12 is also preferably Type I. For example, a combination in which the optical absorption material 17 is SrZrS 3 and the nucleus 11 is BaZrS 3 can be cited. In addition, a material combination in which the shell 12 is further SrZrS 3 can be cited. As another example, a combination in which the optical absorption material 17 is SrHfS 3 and the nucleus 11 is BaHfS 3 can be cited. A material combination in which the shell 12 is further SrHfS 3 can be cited. It should be noted that as long as the combination of materials shows a Stokes shift in the energy band alignment between the optical absorption material 17 and the nucleus 11, the optical absorption material 17 may also be a material other than chalcogenide perovskite.

[0201] In addition, the color conversion particle 10 may have a hollow structure with a void 16 inside. For example, as Figure 8 shown in (a), it is also possible to form one or more voids 16 in the nucleus 11. Or, as Figure 8As shown in (b), in the color conversion particle 10 having the outer shell 13 on the outer side of the shell 12, a gap 16 can be formed between the shell 12 and the outer shell 13. By forming the gap 16 that does not exhibit light absorption and light emission inside the color conversion particle 10, the optical properties and shape of the color conversion particle 10 can be adjusted.

[0202] Figure 8 The hollow-structured color conversion particle 10 shown in (a) and (b) can be manufactured, for example, as follows. First, by simultaneously adding organic substances such as fullerenes and carbon nanotubes and soluble salts during synthesis, semiconductor particles containing the organic substances and salts are generated. Then, the organic substances or salts are dissolved using a solvent, or the organic substances or salts are ashed at a high temperature, whereby the hollow-structured color conversion particle 10 can be obtained.

[0203] In addition, foreign substances that do not exhibit light absorption and light emission, such as insulators and other compositions, may be included in the core 11 or the shell 12 of the color conversion particle 10. By including such foreign substances in the core 11 or the shell 12, for example, the light emission efficiency of the color conversion particle 10 can be improved by light scattering and the shape of the color conversion particle 10 can be adjusted.

[0204] In addition, as Figure 8 shown in (c), the core 11 or the shell 12 of the color conversion particle 10 may have a gradient structure in which physical properties such as composition, crystal structure, lattice constant, density, crystal orientation, carrier concentration, band gap, defect density, dielectric constant, and conductivity continuously change in the vertical direction (depth direction) with respect to the interface. The physical properties and chemical properties of the core 11 or the shell 12 continuously change in a gradient manner in the depth direction, whereby the lattice matching is improved and lattice defects can be reduced. As a result, non-radiative recombination is reduced and the light emission efficiency of the color conversion particle can be improved.

[0205] It should be noted that the above gradient structure can be manufactured, for example, by the same method as in the case of manufacturing the multi-layer core 11 and shell 12.

[0206] Furthermore, in the present invention, the shape of the color conversion particle to be synthesized is not particularly limited. For example, spherical, elongated, star-shaped, polyhedral, pyramidal, tetrapod, tetrahedral, flaky, conical, or irregularly shaped cores 11 and / or color conversion particles 10 can be synthesized.

[0207] Hereinafter, the effects of the color conversion particle 10 of the present embodiment will be described.

[0208] The color conversion particle 10 of the present embodiment includes a core 11 and a shell 12 that contains the core 11 and absorbs excitation light. The color conversion particle 10 receives the irradiated excitation light and emits light at the core 11 or at the interface between the core 11 and the shell 12. The chalcogenide perovskite as the material of the core 11 has characteristics of high light absorption coefficient and excellent durability. In addition, the core 11 and the shell 12 have a band alignment that exhibits a Stokes shift. In the present embodiment, by using the difference in the band-edge transition energy between the shell 12 and the core 11, the shell 12 is used to transport photoexcited carriers to the core 11, and the photoexcited carriers encapsulated in the core 11 are recombined to emit light.

[0209] In the present embodiment, by forming the shell 12 outside the core 11 of the chalcogenide perovskite, the part responsible for absorption and the part responsible for light emission are separated in the color conversion particle 10. Thereby, a large Stokes shift can be obtained, and the absorbance can be obtained through the shell 12 without increasing the core 11. Therefore, the reabsorption loss of the light emission caused by the core 11 can be suppressed, and high absorbance and high luminous efficiency can be achieved.

[0210] In addition, as described above, the color conversion particle 10 of the present embodiment has high absorbance and luminous efficiency. Therefore, compared with conventional quantum dots and the like, the desired color conversion function can be achieved with a smaller amount. In other words, for example, when the color conversion particle 10 of the present embodiment is applied to a color conversion layer of a display device, a device other than lighting, etc., thinning of the color conversion layer and improvement of the yield can be achieved. In the formation of the color conversion layer, the probability of occurrence of defects in the film-forming process increases due to repeated film-forming processes, and as a result, the yield of the color conversion layer decreases. On the contrary, if the color conversion layer can be thinned, the number of film-forming processes can be reduced, so the effective defect rate of the color conversion layer can be reduced.

[0211] In addition, if the band gap of the shell 12 is larger than the band gap of the core 11, the light emitted from the core 11 is hardly absorbed by the shell 12 and is emitted to the outside. Therefore, the reabsorption loss in the shell can also be suppressed. That is, when the band gap of the shell 12 is larger than the band gap of the core 11, the absorbance can be obtained by thickening the shell 12 without increasing the reabsorption loss. Therefore, the luminous efficiency of the color conversion particle 10 can be further improved.

[0212] In addition, if the shell 12 is made of chalcogenide perovskite, the absorbance and durability of the shell 12 can be improved, and the luminous efficiency can be further improved by reducing the defects at the core-shell interface.

[0213] <Product form and usage examples of the color conversion particle 10>

[0214] Next, the product form and usage examples of the color conversion particles 10 will be described. As the product form of the color conversion particles 10, powders, solutions, thin films, sheets, etc. can be cited. In addition, as usage examples of the color conversion particles 10, it is assumed that they are applied to various devices.

[0215] (Powder)

[0216] The powder is a powder in which the color conversion particles 10 are in a condensed state. Hereinafter, the color conversion particles 10 may sometimes be referred to as primary particles, and the particles in which the color conversion particles 10 are in a condensed state may be referred to as secondary particles. The sizes of the primary particles and the secondary particles are not particularly limited, and the primary particles are preferably in the range of 5 nm to 1000 nm. In addition, ligands can be imparted to the surfaces of the primary particles and the secondary particles. In order to improve characteristics such as luminescence characteristics, dispersibility of the color conversion particles, and film-forming properties, other materials can be added as additive materials to the powder of the color conversion particles 10.

[0217] In addition, the usage of the powder of the color conversion particles 10 is not particularly limited. For example, it can be dispersed in a solvent to prepare a solution, or it can be dispersed in a resin or a solid medium to prepare a composite, or it can be made into a sputtering target in the form of a sintered body, or it can be directly used as a source such as an evaporation source in the form of a powder.

[0218] (Solution)

[0219] The solution is a solution in which the color conversion particles 10 are in a state of being dispersed in a solvent. The sizes of the primary particles and the secondary particles are not particularly limited, and the primary particles are preferably in the range of 5 nm to 1000 nm. In addition, "dispersed" means a state in which the color conversion particles 10 float or are suspended in the solvent, and a part of them may have settled. In addition, ligands can be imparted to the surfaces of the primary particles and the secondary particles.

[0220] One or more than two kinds of solvents can be used as the solvent of the solution. As the types of solvents, for example, the following solvents can be cited, but are not limited thereto.

[0221] esters such as water, methyl formate, ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate, pentyl acetate; ketones such as γ-butyrolactone, acetone, dimethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone; ethers such as diethyl ether, methyl tert-butyl ether, diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, 4-methyldioxolane, tetrahydrofuran, methyltetrahydrofuran, anisole, phenetole; alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, 1-pentanol, 2-methyl-2-butanol, methoxypropanol, diacetone alcohol, cyclohexanol, 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, triethylene glycol dimethyl ether; organic solvents with amide groups such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, acetamide, N,N-dimethylacetamide; organic solvents with nitrile groups such as acetonitrile, isobutyronitrile, propionitrile, methoxyacetonitrile; organic solvents with carbonate groups such as ethylene carbonate, propylene carbonate; organic solvents with halogenated hydrocarbon groups such as dichloromethane, chloroform; organic solvents with hydrocarbon groups such as n-pentane, cyclohexane, n-hexane, benzene, toluene, xylene; dimethyl sulfoxide, etc.

[0222] In addition, in order to improve characteristics such as light emission characteristics, dispersibility of the color conversion particles 10, and film-forming properties, an acid, a base, a binder material, or the like can be added as an additive material to the above solution.

[0223] In addition, the use of the above solution is not particularly limited. For example, it can be used for film formation by a coating method, a spraying method, a doctor blade method (other solution film-forming methods), production of a composite using a composite with a solid dispersion medium, or production of a device using them.

[0224] (thin film)

[0225] The thin film is a thin film in a state where the color conversion particles 10 are aggregated into a planar shape. The sizes of the primary particles and the secondary particles are not particularly limited, and the primary particles are preferably in the range of 5 nm to 1000 nm. In addition, a ligand can be imparted to the surfaces of the primary particles and the secondary particles. In order to improve characteristics such as light emission characteristics and dispersibility of the color conversion particles 10, other materials can be added as additive materials to the above thin film.

[0226] The method for producing the above thin film is not particularly limited. For example, a coating method, a spraying method, a doctor blade method, an inkjet method, and other film formation based on solution film formation, or a vacuum process such as a sputtering method or a vacuum evaporation method can be used to produce the thin film. In addition, the color conversion particles 10 can be formed into a film by a coating or other method, and then become a state where the particle shape is not maintained through firing or other processing.

[0227] (Sheet)

[0228] The sheet is a sheet in a planar state in which the dispersion medium for dispersing the colored conversion particles 10 is in a planar state. The sizes of the primary particles and the secondary particles are not particularly limited, and the primary particles are preferably in the range of 5 nm to 1000 nm. In addition, ligands can be imparted to the surfaces of the primary particles and the secondary particles.

[0229] As the material used as the dispersion medium of the sheet, polymers well-known to those skilled in the art that can be used for this purpose can be arbitrarily applied. In a suitable embodiment, such a polymer is substantially translucent or substantially transparent.

[0230] For example, polymer types that can be used as the dispersion medium of the sheet include polyvinyl butyral: polyvinyl acetate, silicone, and derivatives of silicone, but are not limited to these. In addition, derivatives of silicone include polyphenylmethylsiloxane, polyphenylalkylsiloxane, polydiphenylsiloxane, polydialkylsiloxane, fluorinated silicones, and vinyl- and hydride-substituted silicones, ionomers, polyethylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polypropylene, polyester, polycarbonate, polystyrene, polyacrylonitrile, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-methacrylic acid copolymer film, nylon, etc., but are not limited to these.

[0231] In order to improve characteristics such as the light-emitting characteristics and the dispersibility of the color conversion particles 10, other materials such as silica fine particles and the solvents described in the above solution can be added as additive materials to the above sheet.

[0232] The method for producing the above sheet is not particularly limited. For example, the sheet can be produced by kneading and stretching a powder and a dispersion medium, or by mixing and coating an ink containing the color conversion particles 10 with a dispersion medium or its precursor.

[0233] (Device)

[0234] As the use of the color conversion particles 10, or the above powder, solution, film, or sheet, it is contemplated to be applied to the down-conversion of ultraviolet light or blue light, etc. in various devices. As the types of devices, for example, light-emitting devices such as LEDs and organic ELs, display devices including the light-emitting devices, lighting devices including the light-emitting devices, image sensors, photoelectric conversion devices, bioluminescent markers, etc. can be cited.

[0235] <Example>

[0236] Hereinafter, examples of the color conversion particles of the present invention will be described.

[0237] In the color conversion particles of the example, the material of the core is BaZrS 3, the material of the shell is SrZrS 3 . That is, the core and shell of the color conversion particles in the embodiment are chalcogenide perovskites, which is an example of a combination of materials that is equivalent to the best combination for exhibiting the Stokes shift. As described above, when the core and shell are chalcogenide perovskites, the interface defects between the core and shell are reduced, and high luminous efficiency can be expected.

[0238] Figure 9 is a diagram showing the band alignment of shell / core / shell in the color conversion particles of the embodiment. The origin of the energy on the vertical axis is set to the vacuum level. Regarding the physical property values of the core and shell, refer to the references "Y. Nishigaki et al., Sol. RRL 1900555 (2020)." and "K. Hanzawa et al., J. Am. Chem. Soc. 141, 5343 (2019).", and are comprehensively determined based on other experimental results reports.

[0239] As Figure 9 shown, regarding the band alignment of the shell and core in the embodiment, the E c of the core is lower than the E c of the shell, and the E v of the core is higher than the E v of the shell, so it becomes Type I. Therefore, in the configuration of the embodiment, it is expected that the shell absorbs the excitation light, the excited carriers move to the core and recombine, thereby causing the core to emit light. In addition, in the embodiment, since the band gap E g of the shell is greater than the band gap E g of the core, suppression of reabsorption loss in the shell is also expected.

[0240] In the embodiment, regarding the light absorption and light emission of the color conversion particles, one-dimensional simulation is performed using software (SCAPS-1D). Figure 10 is a diagram showing the results of the simulation of the embodiment. Figure 10 The horizontal axes of the respective diagrams of

[0241] respectively represent the one-dimensional position in the diameter direction in the color conversion particles. 2 In the simulation, the diameter of the core is set to 20 nm, and the thickness of the shell is set to 50 nm. In addition, the wavelength of the excitation light is set to blue light of 450 nm, and it is set that the excitation light is incident from one side (the left side of the diagram) with an illuminance of 100 mW / cm

[0242] Figure 10 of (a) represents the E c distribution curve of the color conversion particles, Figure 10 of (b) represents the E v distribution curve of the color conversion particles. The energy on the vertical axis is based on the Fermi energy E F .

[0243] InFigure 10 In (a) of , the E of the core range (the range where the horizontal axis value is 50 nm - 70 nm) c is lower than the E of the shell range c . In addition, in Figure 10 of (b), the E of the core range v is higher than the E of the shell range v . And Figure 10 the distribution curves of (a) and (b) of Figure 9 are in good agreement with the band alignment shown in

[0244] Figure 10 The (c) of represents the carrier concentration distribution curve of the color conversion particles. Figure 10 The solid line in the (c) of represents the distribution curve of electrons, Figure 10 and the dashed line in the (c) of represents the distribution curve of holes.

[0245] In Figure 10 the (c) of , the carrier density in the core range (the range where the horizontal axis value is 50 nm - 70 nm) is higher than that of the shell range. Therefore, from the (c) of Figure 10 it can be seen that the carriers excited by the light absorbed by the shell effectively move to the core and are enclosed in the core.

[0246] Figure 10 The (d) of represents the generation rate and recombination rate of carriers. Figure 10 The dashed line in the (d) of represents the distribution curve of the carrier generation rate, Figure 10 and the solid line in the (d) of represents the distribution curve of the carrier recombination rate.

[0247] As shown in the (d) of Figure 10 , the carrier generation rate is the highest on the left side of the figure where the excitation light is incident. In addition, since the light absorption coefficient of the chalcogenide perovskite is very large, the carrier generation rate decreases rapidly as it moves to the right side of the figure. It can be seen that most of the carrier excitation based on light absorption occurs in the shell range of 0 nm - 50 nm.

[0248] On the other hand, the carrier recombination rate shows a high value in the core range (the range where the horizontal axis value is 50 nm - 70 nm), and in the shell range, the value is approximately zero. That is, the luminescence caused by the recombination of carriers is almost all caused by the photoexcited carriers that move to the core.

[0249] Therefore, according to the simulation results, the transport of photoexcited carriers from the shell to the core and the enclosure of photoexcited carriers in the core occur effectively.

[0250] In addition, based on the BaZrS shown in the above-mentioned "Y. Nishigaki et al., Sol. RRL 1900555 (2020)". 3 and SrZrS 3 The optical coefficients of BaZrS 3 and SrZrS 3 The light absorption coefficient of BaZrS 3 PL (Photoluminescence) peak.

[0251] Figure 11 It means BaZrS 3 and SrZrS 3 The light absorption coefficient of BaZrS 3 Graph of various distribution curves of PL emission spectra. Figure 11 The horizontal axis represents wavelength.

[0252] BaZrS as core material 3 The PL emission spectrum ( Figure 11 The solid line in the middle shows a sharp emission peak with a half-width of about 30 nm. This is because the absorption edge (the rise of the light absorption coefficient near the band edge) of chalcogenide perovskite is very steep.

[0253] in addition, Figure 11 The single dot-dashed line represents BaZrS 3 The distribution curve of the light absorption coefficient, Figure 11 The dashed line represents SrZrS 3 In the region where the lower part of the distribution curve of the light absorption coefficient overlaps with the distribution curve of the PL emission spectrum, the luminescence can be reabsorbed.

[0254] That is, it can be seen that if only BaZrS is used as the core material 3 The luminescence can be reabsorbed if the color conversion is performed. 3 In the case of a core, if the particle size is increased in order to increase absorbance, the reabsorption also increases, so the absorbance and the loss of reabsorption are in a trade-off relationship.

[0255] On the other hand, SrZrS 3 The distribution curve of the light absorption coefficient of BaZrS 3 The lower part of the distribution curve of the PL emission spectrum of BaZrS is almost not overlapped. 3 Nuclear Applications of SrZrS 3 In the case of the shell, resorption in the shell hardly occurs.

[0256] In an embodiment, the color conversion particles are of a core-shell structure, and the absorbance of the excitation light is obtained by SrZrS 3 obtained, SrZrS 3 is a shell material having a bandgap larger than that of BaZrS 3 which is the core. Therefore, in the configuration of the embodiment, the absorbance can be obtained by thickening the shell without increasing the reabsorption loss.

[0257] Figure 12 is a diagram showing the correspondence between the combination of the core and shell materials in the embodiment and the comparative example, the type of band alignment, and the manifestation of the Stokes shift. In Figure 12 , for 16 combinations (4×4 = 16) in the case where the four materials SrZrS 3 , BaZrS 3 , SrHfS 3 , and BaHfS 3 are applied to the core and shell materials, the type of band alignment and the presence or absence of the manifestation of the Stokes shift are respectively correlated and shown.

[0258] In Figure 12 , the combination of materials showing the Stokes shift (Yes) is the embodiment, and the combination of materials not showing the Stokes shift (No) is the comparative example. Here, in Figure 12 , when the core and the shell are made of the same material, the type of band alignment is flat in all cases, and the Stokes shift does not appear in these cases.

[0259] In Figure 12 , when the core material is SrZrS 3 and the shell material is BaZrS 3 , the type of band alignment is Inverse Type I, and the Stokes shift does not appear in this combination. On the other hand, when the core material is SrZrS 3 and the shell material is SrHfS 3 or BaHfS 3 , the type of band alignment is Type II in both cases, and the Stokes shift appears in their combinations.

[0260] In Figure 12 , when the core material is BaZrS 3 and the shell material is SrZrS 3 , the type of band alignment is Type I. In addition, when the core material is BaZrS 3 and the shell material is SrHfS 3 or BaHfS 3In the case of, the type of band alignment is all Type II. Stokes shift appears in all of these combinations.

[0261] In Figure 12 when the material of the core is SrHfS 3 and the material of the shell is SrZrS 3 or BaZrS 3 the type of band alignment is all Type II, and Stokes shift appears in all of their combinations. On the other hand, when the material of the core is SrHfS 3 and the material of the shell is BaHfS 3 the type of band alignment is Inverse Type I, and Stokes shift does not appear in this combination.

[0262] In Figure 12 when the material of the core is BaHfS 3 and the material of the shell is SrZrS 3 or BaZrS 3 the type of band alignment is all Type II. In addition, when the material of the core is BaHfS 3 and the material of the shell is SrHfS 3 the type of band alignment is Type I. Stokes shift appears in all of these combinations.

[0263] It should be noted that when the material of the core is BaZrS 3 and the material of the shell is SrZrS 3 and when the material of the core is BaHfS 3 and the material of the shell is SrHfS 3 since the type of band alignment is Type I, color conversion particles with particularly excellent luminescence characteristics can be obtained.

[0264] As described above, the embodiments of the present invention have been described, but the embodiments are presented as an example and are not intended to limit the scope of the present invention. The embodiments can be implemented in various ways other than those described above, and various omissions, substitutions, changes, etc. can be made without departing from the gist of the present invention. The embodiments and their modifications are included in the scope and gist of the present invention, and the invention described in the claims and its equivalents are also included in the scope and gist of the present invention.

[0265] In addition, this application claims priority based on Japanese Patent Application No. 2020-195173 filed on November 25, 2020, and incorporates the entire contents of Japanese Patent Application No. 2020-195173 into this application.

[0266] Description of Reference Numerals

[0267] 10…Color conversion particles

[0268] 11…Nucleus

[0269] 12, 12a, 12b…Shell

[0270] 13…Outer shell

[0271] 14…Ligand

[0272] 16…Void

Claims

1. A color conversion particle, comprising: a core; and a shell that contains the core and absorbs excitation light, the color conversion particle receives the irradiated excitation light and generates luminescence at the core or at the interface between the core and the shell, the core is composed of a chalcogenide perovskite, the shell is composed of a semiconductor material, The chalcogenide perovskite is ABX 3 The GdFeO shown 3 type orthorhombic perovskite, wherein, A represents a Group 2 element, B represents a Group 4 element, and X represents a chalcogen element, the core and the shell have a band alignment that exhibits a Stokes shift, The energy band alignment satisfies the energy E at the lower end of the conduction band of the shell c_shell being higher than the energy E at the lower end of the conduction band of the core c_core or the energy E at the upper end of the valence band of the shell v_shell being lower than the energy E at the upper end of the valence band of the core v_core satisfying at least any one of the conditions wherein the chalcogen element refers to S, Se, or Te.

2. The color conversion particle according to claim 1, wherein, A, B, and X each contain elements formed by mixing the elements in their respective groups in an arbitrary ratio.

3. The color conversion particle according to claim 1, wherein, The chalcogenide perovskite is selected from SrZrS 3 , SrZrSe 3 , SrHfS 3 , SrHfSe 3 , BaZrS 3 , BaZrSe 3 , BaHfS 3 , BaHfSe 3 and any one of them.

4. The color conversion particle according to claim 1, wherein, The chalcogenide perovskite is (Sr x Ba 1-x )(Zr y Hf 1-y )(S z Se 1-z ), where x, y, and z are values greater than or equal to 0 and less than or equal to 1, respectively. 3 ​ 5. The color conversion particle according to claim 1, wherein, the band gap of the shell is greater than the band gap of the core.

6. The color conversion particle according to claim 5, wherein, The energy band alignment satisfies the condition that the energy E at the lower end of the conduction band of the shell c_shell is higher than the energy E at the lower end of the conduction band of the core c_core and the energy E at the upper end of the valence band of the shell v_shell is lower than the energy E at the upper end of the valence band of the core v_core .

7. The color conversion particle according to claim 1, wherein, the particle size of the core is 1 nm or more and 200 nm or less.

8. The color conversion particle according to claim 7, wherein, the particle size of the core is 1 nm or more and 50 nm or less.

9. The color conversion particle according to claim 8, wherein, the particle size of the core is 1 nm or more and 25 nm or less.

10. The color conversion particle according to claim 1, wherein, the shell has multiple layers.

11. The color conversion particle according to claim 1, wherein, the shell contains multiple cores.

12. The color conversion particle according to claim 1, wherein, the core encapsulates a light-absorbing material.

13. The color conversion particle according to claim 1, wherein, at least one of the shell or the core contains foreign substances or voids.

14. The color conversion particle according to claim 1, wherein, at least one of the shell or the core has a structure in which the physical properties change in a gradient manner in the depth direction.

15. The color conversion particle according to claim 1, wherein, the shell is composed of a semiconductor material containing Group VI.

16. The color conversion particle according to claim 1, wherein, the shell is composed of a chalcogenide perovskite different from the core, a II-VI semiconductor, a III-V semiconductor, a I-III-VI semiconductor, a I-II-IV-VI semiconductor, a IV-VI semiconductor, a halide perovskite semiconductor, an oxide perovskite, an organic-inorganic perovskite, Si, a carbon material, or a mixed crystal compound thereof.

17. The color conversion particle according to claim 1, wherein, the shell is composed of a chalcogenide perovskite different from the core.

18. The color conversion particle according to claim 17, wherein, The chalcogenide perovskite different from the core is selected from SrZrS 3 、SrZrSe 3 、SrHfS 3 、SrHfSe 3 、BaZrS 3 、BaZrSe 3 、BaHfS 3 、BaHfSe 3 、Sr 2 Ba n-1 Zr n S 3n+1 、Sr 2 Ba n-1 Zr n Se 3n+1 、Sr n+1 Zr n S 3n+1 、Sr n+1 Zr n Se 3n+1 、Ba 2 Sr n-1 Zr n S 3n+1 、Ba 2 Sr n-1 Zr n Se 3n+1 、Ba n+ 1 Zr n S 3n+1 、Ba n+1 Zr n Se 3n+1 、Sr 2 Ba n-1 Hf n S 3n+1 、Sr 2 Ba n-1 Hf n Se 3n+1 、Sr n+1 Hf n S 3n+1 、Sr n+1 Hf n Se 3n+1 、Ba 2 Sr n-1 Hf n S 3n+1 、Ba 2 Sr n-1 Hf n Se 3n+1 、Ba n+1 Hf n S 3n+1 、Ba n+1 Hf n Se 3n+1 any one of them, where n is an integer of 1 or more.

19. The color conversion particle according to claim 17, wherein, The chalcogenide perovskite different from the nucleus is (Sr x Ba 1-x )(Zr y Hf 1-y )(S z Se 1-z ), 3 or (Sr x’ Ba 1-x’ ), 2 (Sr x Ba 1-x ), n-1 (Zr y Hf 1-y ), n (S z Se 1-z ), 3n+1 , where x, x', y, and z are values greater than or equal to 0 and less than or equal to 1, and n is a positive integer.

20. The color conversion particle according to claim 1, wherein, The core is BaZrS 3 , and the shell is composed of a semiconductor material.

21. The color conversion particle according to claim 1, wherein, The core is BaHfS 3 , and the shell is composed of a semiconductor material.

22. The color conversion particle according to claim 1, wherein, The chalcogenide perovskite is selected from CaTiS 3 , CaTiSe 3 , CaTiTe 3 , CaZrS 3 , CaZrSe 3 , CaZrTe 3 , CaHfS 3 , CaHfSe 3 , CaHfTe 3 , SrTiS 3 , SrTiSe 3 , SrTiTe 3 , SrZrS 3 , SrZrSe 3 , SrZrTe 3 , SrHfS 3 , SrHfSe 3 , SrHfTe 3 , BaTiS 3 , BaTiSe 3 , BaTiTe 3 , BaZrS 3 , BaZrSe 3 , BaZrTe 3 , BaHfS 3 , BaHfSe 3 , BaHfTe 3 and any one of them.

23. The color conversion particles according to claim 1, wherein, The chalcogenide perovskite is (Ca x Sr x’ Ba 1-x-x’ )(Ti y Zr y’ Hf 1-y-y’ )(S z Se z’ Te 1-z-z’ ) 3 , wherein x, x', y, y', z, and z' are each a value of 0 or more and 1 or less, x + x' ≤ 1, y + y' ≤ 1, and z + z' ≤ 1.

24. A powder comprising the color conversion particles according to any one of claims 1 to 23.

25. A solution comprising the color conversion particles according to any one of claims 1 to 23.

26. A film comprising the color conversion particles according to any one of claims 1 to 23.

27. A sheet comprising the color conversion particles according to any one of claims 1 to 23.

28. A device comprising the color conversion particles according to any one of claims 1 to 23.

Images