Processing method for luminescent nanoparticles

Abstract

(i) A step of providing a mixture of (a) a salt and (b) luminescent nanoparticles or precursors thereof, wherein the luminescent nanoparticles are (A 1-x B x )3(C 1-y D y )5O 12 A method for processing luminescent nanoparticles or their precursors is provided, comprising: (ii) heating the mixture at a first temperature for a first time, wherein the first temperature is 800°C or higher and the first time is 10 minutes or higher; and (iii) heating the mixture at a second temperature for a second time under a reducing atmosphere, wherein the second temperature is 500°C or higher and the second time is 1 hour or higher. Nanoparticles that can be obtained by this method are further provided.

Description

[Technical Field]

[0001] This invention relates to the processing of luminescent particles. Furthermore, this invention relates to processed luminescent particles. Furthermore, this invention relates to a luminescent composition containing processed luminescent particles and a method for producing the luminescent composition. Furthermore, this invention relates to the uses of the processed luminescent particles or luminescent composition of this invention and devices containing them. [Background technology]

[0002] Emitting downconversion materials play an important role in lighting, particularly in solid-state lighting devices for displays. Such materials can also be used, for example, as tagants in security inks. International Publication No. 2018 / 167266 discloses a composition comprising an emissive material and a sensitizing material, wherein the sensitizing material is selected such that the sensitizing material has an emission spectrum that at least partially overlaps one or more excitation bands of the emissive material, and the emissive material and the sensitizing material are arranged relative to each other to allow non-radiative energy transfer from the sensitizing material to the emissive material. The application also describes a method for manufacturing the same.

[0003] Non-radiative energy transfer from a sensitizing material to a luminescent material (also known as fluorescence resonance energy transfer, or FRET) involves the non-radiative transfer of energy from excited sensitizing ions in the sensitizing material to acceptor (or luminescent) ions in the luminescent material. This is demonstrated by the increase in energy release from luminescent ions in the luminescent material upon selective excitation of sensitizing ions in the sensitizing material.

[0004] Nanomaterials are interesting because their large surface area and small volume allow for the spatially close placement of luminescent materials to utilize interparticle FRET (free reticular activity). To effectively utilize interparticle FRET, the size of the luminescent particles is desirable to be very small (less than 10 nm). However, suitable nanomaterials, due to their small size and low crystallinity, may have poor quality (chemically, stably, optically, and / or physically). International Publication 2021 / 043762 teaches that annealing of nanoparticles improves lattice densification (quality), homogeneity, phase purity, and luminescence properties. However, further improvements are needed.

[0005] Cerium-doped yttrium aluminum garnet (YAG:Ce) is a benchmark phosphor for solid-state LED lighting. While YAG:Ce is highly efficient in microcrystalline form (or as a bulk single crystal / ceramic), at the nanoscale it suffers from problems such as low luminescence intensity, low conversion efficiency, and poor stability.

[0006] Small YAG:Ce nanoparticles of 5 nm can be obtained by wet chemical synthesis methods (solvothermal, precipitation, sol-gel, etc.). However, these synthesized nano-YAG:Ce may contain impurities, have a weak lattice, and exhibit poor photoluminescence (PL) properties.

[0007] Song, Dong, Shao and Jiang, J Mater Sci (2018) 53:15196-15203 is Y3Al5O 12 The document discloses a method for producing Ce nanophosphors. However, it was found that this method does not produce the small size described, even after heating at 1000°C for 4 hours. Furthermore, this method is limited to materials produced by precipitation.

[0008] Therefore, there is still a need for luminescent nanomaterials that are smaller in size and have improved quality and stability. Furthermore, there is a need for luminescent compositions with high quantum yield (QY) and improved stability, as well as methods for producing them.

Summary of the Invention

[0009] This invention relates to (i) providing a mixture of (a) a salt and (b) luminescent nanoparticles or a precursor thereof, wherein the luminescent nanoparticles are (A 1-x B x )3(C 1-y D y )5O 12 garnet nanoparticles (where A consists of one or more of yttrium, lutetium, gadolinium, B consists of one or more rare earth elements, C consists of one or more of aluminum, gallium and scandium, D consists of one or more transition metal ions, x is 0 or more and 1 or less, y is 0 or more and 1 or less, and x + y exceeds 0), (ii) heating the mixture at a first temperature for a first time, where the first temperature is 800 °C or higher and the first time is 10 minutes or longer, and (iii) heating the mixture at a second temperature for a second time under a reducing atmosphere, where the second temperature is 500 °C or higher and the second time is 1 hour or longer, and provides a method for treating luminescent nanoparticles or a precursor thereof.

[0010] The method of this invention makes it possible to obtain luminescent nanoparticles with improved luminescence quantum yield compared to luminescent nanoparticles that are untreated or have only undergone one heat treatment. The inventors have found that the combination of mixing the salt and two heat treatments results in small nanoparticles with improved PLQY and photostability.

[0011] This invention provides luminescent nanoparticles obtainable by the method of this invention, which are (A 1-x B x )3(C 1-y D y )5O 12Garnet nanoparticles (wherein A is composed of one or more of yttrium, lutetium, and gadolinium; B is composed of one or more rare earth elements; C is composed of one or more of aluminum, gallium, and scandium; D is composed of one or more transition metal ions; x is between 0 and 1; y is between 0 and 1; and x+y is greater than 0), and the luminescent nanoparticles are, - BET surface area is 10m 2 D exceeding / g, or measured by transmission electron microscope (TEM) 50 The wavelength is 0.5 nm to 100 nm, more preferably 5 nm to 50 nm. - The photostability during storage is such that the luminescence intensity after 2 weeks of storage in a non-inert atmosphere is at least 80% of the initial luminescence intensity. - Strength 0.1W / cm 2 When irradiated with 450nm light, it exhibits photostability such that at least 80% of the initial emission intensity remains after 10 hours, and preferably at least 80% remains after 15 hours.

[0012] If B consists of at least Ce, the nanoparticles of this invention are - The emission quantum yield is greater than 25%, preferably greater than 30%. - The peak ratio in the excitation spectra (455 nm and 380 nm) exceeds 20.

[0013] The properties of the luminescent nanoparticles of this invention have been improved in the following way.

[0014] This invention further provides a light-emitting composition containing the light-emitting nanoparticles of this invention or light-emitting nanoparticles that can be obtained by the method of this invention. [Brief explanation of the drawing]

[0015] [Figure 1]Figure 1 shows the emission spectra of nano-sized YAG:Ce obtained by single-step annealing, i.e., annealing in air at 1020°C for 2 hours (dotted line, Comparative Example 1), and nano-sized YAG:Ce obtained by two-step annealing, i.e., first annealing in air at 1020°C for 2 hours, and then annealing in a reducing atmosphere at 800°C for 8 hours (solid line, Example 1). The excitation wavelength was 440 nm. [Figure 2] Figure 2 shows the emission spectra of nano-sized YAG:Ce obtained by single-step annealing, i.e., annealing in air at 1000°C for 2 hours (dotted line, Comparative Example 2), and nano-sized YAG:Ce obtained by two-step annealing, i.e., first annealing in air at 1000°C for 2 hours, and then annealing in a reducing atmosphere at 800°C for 8 hours (solid line, Example 2). The excitation wavelength was 440 nm. [Figure 3] Figure 3 shows the emission spectra of nano-sized YAG:Ce obtained by one-step annealing, i.e., annealing in air at 900°C for 2 hours (dotted line, Comparative Example 3), and nano-sized YAG:Ce obtained by two-step annealing, i.e., first annealing in air at 900°C for 2 hours, and then annealing in a reducing atmosphere at 800°C for 8 hours (solid line, Example 3). The excitation wavelength was 440 nm. [Figure 4] Figure 4 shows a TEM image of nano-sized YAG:Ce (Example 1) that was annealed in two stages, first at 1020°C for 2 hours in air, and then at 800°C in a reducing atmosphere for 8 hours. [Figure 5] Figure 5 shows a TEM image of nano-sized YAG:Ce (Example 2) that was annealed in two stages, first at 1000°C in air for 2 hours, and then at 800°C in a reducing atmosphere for 8 hours. [Figure 6] Figure 6 shows the emission spectrum (solid line) and excitation spectrum (dotted line) of a nano-sized YAG (Example 4) annealed in two steps using only a salt matrix, i.e., annealed in air at 1000°C for 2 hours, followed by annealing in a reducing atmosphere at 800°C for 8 hours. The excitation wavelength was 440 nm. [Figure 7]Figure 7 shows a TEM image of nano-sized YAG:Ce (Example 4) that was annealed in two steps using only a salt matrix, i.e., first in air at 1000°C for 2 hours, and then in a reducing atmosphere at 800°C for 8 hours. [Figure 8] Figure 8 shows the excitation spectra of solvothermal Ce-doped nanosize YAG:Ce before (dotted line) and after (solid line) a two-step annealing experiment at temperatures above 800°C. The solvothermal synthesis of the nanoparticle precursor was performed at temperatures below 400°C. The excitation spectra were recorded by monitoring the emission at 550 nm. [Modes for carrying out the invention]

[0016] Detailed description of the invention Luminescent nanoparticles The luminescent nanoparticles are (A (1-x) B x )3(C (1-y) D y )5O 12 Garnet nanoparticles (wherein A consists of one or more of yttrium, lutetium, and gadolinium; B consists of one or more rare earth elements; C consists of one or more of aluminum, gallium, and scandium; D consists of one or more transition metal ions; x is between 0 and 1; y is between 0 and 1; and x+y is greater than 0).

[0017] Preferably, B is made of cerium and C is made of aluminum. These are cerium-doped aluminum garnet type nanoparticles such as yttrium aluminum garnet (YAG:Ce), lutetium aluminum garnet (LuAG:Ce), gadolinium aluminum garnet (GdAG:Ce), or combinations thereof such as (Y,Lu)AG:Ce.

[0018] Preferably, the luminescent nanoparticles are obtained by a solvothermal method. Sorvothermal synthesis is carried out by heating a metal salt suspended in a solvent to obtain a colloidal solution of ultrafine metal oxide particles.

[0019] Preferably, the solvothermal method is a glycothermal method. In glycothermal synthesis, glycol is used as the solvent. Such a glycothermal method is described in J. Mater. Chem. C, 2017, 5, 12561. Glycols are aliphatic diols. Glycols suitable for use in glycothermal synthesis are ethylene glycol, 1,2-propanediol, 1,2-butanediol, 1,3-propanediol, and 1,4-butanediol. More preferably, luminescent nanoparticles are obtained by glycothermal synthesis, with 1,4-butanediol as the glycol solvent.

[0020] Preferably, a cosolvent is used in the glycothermal method. The cosolvent can reduce the size and aggregation of nanoparticles. More preferably, the luminescent nanoparticles are obtained by the glycothermal method, and the cosolvent is 1,4-butanediol, which is a glycol solvent, and further contains at least one of ethylene glycol, diethylene glycol, and polyethylene glycol 200.

[0021] salt In the methods according to all aspects of this invention, a suitable salt having a melting point I above the temperature at which the mixture is heated may be used. Preferably, the melting point of the salt is 800°C or higher, more preferably 1000°C or higher.

[0022] Preferably, the salt contains Se as an anion. 2- S 2- Cl - F - , Br - , I - SO4 2- , PO4 3- Or NO3 - Or a combination thereof, and containing H as a cation. + Li + na + , K + Be 2+ Ca 2+ , Al 3+ Ba 2+ Mg 2+ Or Sr 2+or a combination thereof. More preferably, the salt is K2SO4(T m (=1069℃)

[0023] The salt is preferably provided as a crystalline solid.

[0024] If necessary, the salt may be crushed or ground. The smaller the particles, the more uniformly the salt will mix with the luminescent material.

[0025] (i) Providing a mixture of salt and luminescent nanoparticles A method according to all aspects of this invention involves the preparation of a mixture comprising a salt and luminescent nanoparticles.

[0026] A mixture containing salt and luminescent nanoparticles can be prepared by a suitable method.

[0027] In a preferred embodiment (hereinafter also referred to as A), the preparation of the mixture comprises a dry mixing of (i) a salt and (ii) luminescent nanoparticles. Those skilled in the art will understand that in this embodiment, the luminescent nanoparticles and the salt are mixed as a dry solid. This embodiment has the advantage that no suspension, dispersion and / or evaporation steps are required. Preferably, the dry mixing comprises grinding the mixture containing (i) a salt and (ii) luminescent nanoparticles.

[0028] In a more preferred embodiment (hereinafter also referred to as B), the preparation of the mixture includes mixing (i) the salt and (ii) the luminescent nanoparticles in a liquid to obtain a dispersion. The liquid may then be separated from the dispersion, preferably by evaporation. The salt may be added to the liquid before, after, or during the dispersion of the luminescent nanoparticles. Preferably, an excess amount of salt that does not completely dissolve is added.

[0029] A suitable liquid can be selected in which the luminescent nanoparticles are sufficiently dispersed. Preferably, the liquid has a relatively low boiling point, which facilitates the removal of the liquid in the later stages of the process. Preferably, the liquid is water or an alcohol. Preferably, the alcohol is a C1-C4 alkanol, such as methanol, ethanol, or propanol.

[0030] Preferably, the mixture is ultrasonically treated in an ultrasonic bath or using an ultrasonic probe. This has the advantage of promoting mixing.

[0031] In a more preferred embodiment (hereinafter also referred to as C), the preparation of the mixture includes the preparation of an emulsion comprising a dispersed phase and a continuous phase, wherein the dispersed phase comprises (i) the salt and (ii) the luminescent nanoparticles. The liquid forming the emulsion may then be separated from the emulsion, preferably by sedimentation of emulsion droplets. Preferably, the dispersed phase is an aqueous phase and the continuous phase is a nonpolar phase (or oil phase). To obtain the nonpolar phase (or oil phase), a suitable nonpolar solvent, for example, C5-C 12 Alkanes, preferably cyclohexane, may be used.

[0032] The emulsion may be manufactured by an appropriate method, for example, by sonication. Sedimentation may be carried out by an appropriate method, for example, by contacting the emulsion with alcohol or acetone and / or by separation by gravity (e.g., centrifugation).

[0033] Preferably, the preparation of a mixture comprising (i) the salt and (ii) the luminescent nanoparticles includes (applicable to each of embodiments A, B, and C) pulverizing the salt, for example by milling or grinding, and / or ultrasonically treating and / or grinding (i) the salt and / or (ii) the luminescent nanoparticles. These treatments may be performed on the materials before, during, or after mixing.

[0034] Salt:Luminescent nanoparticle weight ratio (w / w) There is no upper or lower limit to the weight ratio of salt to luminescent nanoparticles. Preferably, the salt:luminescent nanoparticle (w / w) ratio is selected to be sufficiently high so that the luminescent nanoparticles are separated by a distance sufficient to prevent sintering at high temperatures. As described above, it has been found that increasing the salt:luminescent nanoparticle (w / w) ratio has the advantage of reducing sintering (aggregation, growth and / or clustering). This effect has been found to be particularly pronounced in embodiments (A) and (B) above.

[0035] Preferably, the weight ratio of salt to luminescent nanoparticles in the mixture is greater than 1 (w / w), preferably greater than 2 (w / w), more preferably greater than 5 (w / w), and most preferably greater than 10 (w / w), with respect to 1 luminescent nanoparticle. Preferably, the weight ratio of salt to luminescent nanoparticles in the mixture is about 50 or more:1, about 100 or more:1, or 200 or more:1, particularly in the case of embodiment (A) or (B) above. A high salt:luminescent nanoparticle weight ratio has been found to lead to good separation of luminescent nanoparticles and good salt matrix properties. It has also been found that a higher salt:luminescent nanoparticle ratio allows the mixture to be heated for a longer period of time without the nanoparticles sintering.

[0036] However, very high weight ratios of salt to luminescent nanoparticles require a very large amount of salt and may not be practical. Therefore, for practical reasons, the weight ratio is preferably about 500 or less:1, more preferably about 100 or less:1. In mixing method (C), the preferred salt to luminescent nanoparticle ratio may be lower. Preferably 10 or less:1 (w / w), more preferably 5 or less:1 (w / w) is used.

[0037] As those skilled in the art will understand, in the expression of proportions in this specification, the weight of luminescent nanoparticles refers to the total weight of luminescent nanoparticles present in the mixture.

[0038] (ii) Heating the mixture at a first temperature for a first time. The mixture is heated at a first temperature for a first time. Heating the luminescent nanoparticles can induce and / or promote crystallinity by removing crystal defects in the lattice.

[0039] The first temperature is 800°C or higher. The first temperature is preferably 900°C or higher. The first temperature is preferably 1500°C or lower, more preferably 1250°C or lower. Crystal defects cannot be removed at low temperatures. At high temperatures, the salt may dissolve, and a large amount of energy is required, making it impractical.

[0040] The first time is 10 minutes or more. The first time is preferably 30 minutes or more, more preferably 1 hour or more. The first time is preferably 8 hours or less, more preferably 5 hours or less, most preferably 3 hours or less. With a short heating time, crystal defects may not be removed.

[0041] The higher the temperature, the shorter the heating time can be, and the longer the heating time, the lower the temperature can be.

[0042] The heating of the mixture for a first time at a first temperature is carried out in a gaseous state. Preferably, the gaseous state is air or an inert gas. When heating the mixture in air, no special measures are required. The inert gas may be N2 or Ar.

[0043] (iii) Heating the mixture in a reducing atmosphere for a second time at a second temperature. The mixture is heated under a reducing atmosphere at a second temperature for a second time. This process was found to yield luminescent nanoparticles exhibiting excellent stability and luminescence.

[0044] The second temperature is 500°C or higher. The second temperature is preferably 600°C or higher, and more preferably 700°C or higher. The second temperature is preferably 1050°C or lower, and more preferably 900°C or lower. At high temperatures in a reducing atmosphere, the luminescent material and salt may dissolve. At low temperatures, it may not be effective.

[0045] The second time is 1 hour or more. The second time is preferably 2 hours or more, more preferably 5 hours or more, and even more preferably 7 hours or more. The second time is preferably 12 hours or less, and more preferably 9 hours or less.

[0046] The higher the temperature, the shorter the heating time can be, and the longer the heating time, the lower the temperature can be.

[0047] In this specification, a reducing atmosphere is an atmosphere in which oxidation is prevented and which contains an active reducing gas such as hydrogen or carbon monoxide. Preferably, the reducing atmosphere contains carbon monoxide.

[0048] Heating under a reducing atmosphere may be carried out in a manner known to those skilled in the art. Preferably, heating under a reducing atmosphere is carried out by placing the mixture in a first crucible, placing the first crucible in a second crucible, and further adding the carbon source to the second crucible. This is also known as the "double crucible method." Heating in the double crucible causes the carbon to be partially oxidized to carbon monoxide.

[0049] (iv) Removal of salt from the mixture Typically, after heat treatment, the luminescent nanoparticles are separated from the mixture. The salt may be removed from the mixture by an appropriate method. The salt is removed by contacting the liquid with a solvent, preferably water, that can dissolve the salt. In a preferred embodiment, the salt is K2SO4 and the solvent is water.

[0050] Luminescent nanoparticles obtainable by the method of this invention A luminescent nanoparticle that can be obtained by the described method is provided. The luminescent nanoparticle is (A 1-x B x )3(C 1-y D y )5O 12Garnet nanoparticles (wherein A consists of one or more of yttrium, lutetium, and gadolinium; B consists of one or more rare earth elements; C consists of one or more of aluminum, gallium, and scandium; D consists of one or more transition metal ions; x is between 0 and 1; y is between 0 and 1; and x+y is greater than 0).

[0051] Preferably, A consists of at least one selected from the group consisting of yttrium and lutetium, and B consists of at least one of cerium, terbium, and europium. More preferably, C is aluminum, and B is cerium, europium, terbium, or a combination of terbium and europium.

[0052] The doping concentration depends on the type of ion. Preferably, when B consists of cerium, the molar concentration of cerium relative to the sum of A and B is 0.05 to 5%. Preferably, when B consists of europium, the molar concentration of europium relative to the sum of A and B is 0.1 to 20%. Preferably, when B consists of terbium, the molar concentration of terbium relative to the sum of A and B is 20 to 100%. Combinations of preferred doping ranges are also possible, such as when B contains both terbium and europium.

[0053] The properties of luminescent nanoparticles have improved.

[0054] Luminescent nanoparticles treated by the described method have a BET surface area of ​​10 m². 2 D exceeding / g, or measured by transmission electron microscope (TEM) 50 The wavelength is between 0.5 nm and 100 nm, more preferably between 5 nm and 50 nm. Luminescent nanoparticles obtained by the precipitation method generally form a network structure and are more suitable for definition by BET surface area. Luminescent nanoparticles obtained by the solvothermal method are individual particles suitable for measurement using TEM.

[0055] The luminescence quantum yield of nanoparticles exceeds 25%, preferably exceeds 30%. The luminescence quantum yield is determined by the integrating sphere method, by comparing the absorbed and emitted photons of the sample with a reference. The quantum yield is then determined as the ratio of the amount of emitted photons to the amount of photons absorbed by the sample.

[0056] When Ce is used as a dopant, the excitation spectrum of Ce-induced luminescent nanoparticle materials in garnet shows a peak intensity ratio (455:380) greater than 20, measured at 455 nm and 380 nm. This is different from cerium-doped aluminum garnet nanoparticles that have not been treated at high temperatures, where the excitation probability at 380 nm is much stronger than that of annealed or bulk cerium aluminum garnet, and therefore the peak ratio is much lower than 20.

[0057] The luminescent nanoparticles exhibit improved storage stability. Their photostability during storage is such that, after two weeks of storage in a non-inert atmosphere, their luminescence intensity is at least 80% of the initial luminescence intensity. Many luminescent nanoparticle materials have poor photostability.

[0058] These luminescent nanoparticles exhibit improved photostability. The photostability after irradiation is such that at least 80% of the initial luminescence intensity remains after 10 hours, preferably at least 80% after 15 hours. Irradiation is performed with a light intensity of at least 0.1 W / cm². 2 This is done with 450nm light.

[0059] Luminescent composition Nanoparticles that can be obtained by the method of this invention or a light-emitting composition containing nanoparticles of this invention are further provided.

[0060] Since the method of this invention includes a salt calcination step, the luminescent composition containing nanoparticles of this invention contains at least a trace amount of salt. Therefore, the luminescent composition may contain at least 800 ppm (by weight) of one or more elements selected from the group Li, Na, Ba, K, Be, Ca, Mg, or Sr, and at least 800 ppm (by weight) of one or more elements selected from the group Se, S, Cl, F, Br, I, P, or Nr. When K2SO4 is used as the salt, the luminescent composition may contain 1300 ppm (by weight) of K and 1100 ppm (by weight) of S.

[0061] Preferably, the light-emitting composition contains a first light-emitting material and a second light-emitting material, wherein at least one of the first light-emitting material or the second light-emitting material contains nanoparticles of the present invention or nanoparticles that can be obtained by the method of the present invention.

[0062] Preferably, the light-emitting composition contains a first light-emitting material capable of emitting light in a first wavelength range and a second light-emitting material capable of absorbing light in a second wavelength range, and has an emission spectrum that at least partially overlaps with one or more excitation bands of the first light-emitting material. At least one of the first light-emitting material or the second light-emitting material includes nanoparticles of the present invention or nanoparticles that can be obtained by the method of the present invention.

[0063] Preferably, the first light-emitting material and the second light-emitting material are arranged relative to each other so as to enable non-radiative energy transfer from the second light-emitting material to the first light-emitting material.

[0064] The first light-emitting material is capable of emitting light in a first wavelength range. Those skilled in the art will understand that the first light-emitting material functions as the light-emitting material in the light-emitting composition of this invention. The first wavelength range may be any wavelength range of interest. Preferred wavelength ranges will be described later.

[0065] The second luminescent material can absorb light in the second wavelength range. Those skilled in the art will understand that the second luminescent material functions as a sensitizing material in the luminescent composition of this invention. The second wavelength range may be any wavelength range of interest. Preferred wavelength ranges will be described later.

[0066] When the second luminescent material is excited by light in the second wavelength range, it has an emission spectrum that at least partially overlaps with one or more of the excitation bands of the first luminescent material. Those skilled in the art can appropriately determine the spectral overlap based on spectra known in the art or by obtaining spectra through routine experiments such as those disclosed in WO 2020 / 053429.

[0067] Preferably, the overlap between the emission spectrum of the second material and one or more excitation bands of the first material is within a wavelength range of blue (440 - 480 nm), green (510 - 5,60 nm), or yellow (560 - 580 nm).

[0068] Preferably, the first luminescent material and the second luminescent material are arranged relative to each other to enable non-radiative energy transfer (also referred to as fluorescence resonance energy transfer, FRET) from the second luminescent material (sensitizer material) to the first luminescent material (energy-emitting material). Generally, this involves proximity between the first and second luminescent materials, for example, including from about 0.5 nm to about 20 nm. Those skilled in the art are fully aware of how non-radiative energy transfer is achieved. This is described, for example, in International Publication No. WO 2018 / 167266, the content of which is incorporated herein by reference. Those skilled in the art understand that non-radiative energy transfer includes non-radiative transfer of energy from an excited sensitizer material to an acceptor (or luminescent) ion in the luminescent material. It is evidenced by an increase in selective excitation of the sensitizer material that results in an increase in luminescence from the luminescent ions in the luminescent material. Non-radiative energy transfer may be by either Förster-type energy transfer or Dexter-type energy transfer. Since resonance energy transfer is inversely proportional to the sixth power of the interionic distance (in the case of Förster-type energy transfer) or exponentially proportional to that distance (in the case of Dexter-type energy transfer), those skilled in the art understand that an arrangement enabling non-radiative energy transfer can be achieved by appropriately designing the effective distance between the sensitizer material and the luminescent ions in the luminescent material.

[0069] Preferably, the first luminescent material and / or the second luminescent material includes rare earth metal-doped garnet nanoparticles. This forms a large interaction surface between the first and second materials, (further) enabling non-radiative energy transfer to occur. Rare earth metal-doped garnet nanoparticles have desirable luminescent properties. Examples of rare earth metal-doped garnet nanoparticles suitable for the first luminescent material and / or the second luminescent material are YAG:RE nanoparticles, LuAG:RE nanoparticles, and / or the rare earth metal-doped garnet nanoparticles of this invention.

[0070] Preferably, the first luminescent material is (A 1-x B x )3(C 1-y D y )5O12 The present invention comprises luminescent nanoparticles which are garnet nanoparticles (wherein B is preferably europium, or europium and terbium). These ions have desired absorption / luminescence properties.

[0071] Preferably, the second light-emitting material comprises the light-emitting nanoparticles of the present invention. The light-emitting nanoparticles of the present invention are very suitable for use in light-emitting compositions. 1-x B x )3(C 1-y D y )5O 12 In garnet nanoparticles, B is more preferably cerium, or cerium and terbium. These ions have the desired absorption / luminescence properties.

[0072] Preferably, the first and second light-emitting materials are in the form of nanoparticles. Suitable nanoparticles include at least one particle with dimensions on the nanometer scale, preferably 100 nm or less. The small size reduces the distance between the surface of the first material and the surface of the second material, allowing for (further) non-radiative energy transfer between particles. Providing the two materials as nanoparticles enables efficient mixing and uniform dispersion of the particles, further promoting non-radiative energy transfer between particles.

[0073] As explained above, the minimum dimension D of nanoparticles measured by transmission electron microscopy (TEM) 50 The value is preferably 0.5 nm to 100 nm, more preferably 0.5 nm to 50 nm, and more preferably 0.5 nm to 10 nm. 50 This is defined as the median of the minimum dimensions of nanoparticles, measured in a collection of at least 50 representative particles.

[0074] In another preferred embodiment, the first light-emitting material is provided as a bulk material, and the second light-emitting material is provided on the first light-emitting material. Here, the term “bulk” means, in particular, larger than the nanoscale, e.g., including a microscale with a diameter greater than 100 nm, and / or including.

[0075] As described above, the second light-emitting material may include the light-emitting nanoparticles of the present invention. In a composition in which the second light-emitting material includes the nanoparticles of the present invention, the first light-emitting material is preferably as described below. More preferably, the second light-emitting material is (A) of the present invention. 1-x B x )3(C 1-y D y )5O 12 The first luminescent material, comprising garnet nanoparticles (wherein C is cerium, or cerium and terbium), is described below.

[0076] Those skilled in the art will understand that for a FRET to occur, the first material and the second material must be in close proximity.

[0077] First luminescent material The first light-emitting material can emit light in a first wavelength range. The first wavelength range may be any wavelength range of interest.

[0078] Preferably, the first light-emitting material includes a red or green light-emitting material. In this specification, the term red light-emitting material refers to a material having one or more emission bands in the 600 nm to 700 nm range upon appropriate excitation, and the term green light-emitting material refers to a material having one or more emission bands in the 510 nm to 560 nm range upon appropriate excitation. Providing red or green light-emitting materials may be desirable for color rendering. According to another aspect of this invention, the first light-emitting material is a material having one or more emission bands in the 700 to 1400 nm (IR-A), 580 to 600 nm (amber and / or orange), 560 to 580 nm (yellow), 480 to 510 nm (cyan), 440 to 480 nm (blue), 400 to 440 nm (violet), 315 to 400 nm (UV-A) and / or 280 to 315 nm (UV-B) ranges upon appropriate excitation.

[0079] In a preferred embodiment, the first luminescent material includes a rare-earth-doped fluorescent material. The fluorescent material may be a phosphor doped with a divalent or trivalent rare-earth element. Examples of suitable rare-earth-doped fluorescent materials include, but are not limited to, LaPO4:Eu 3+ (and / or Tb 3+ ), CaAlSiN3:Eu 2+ Y2O3:Eu 3+ (and / or Tb 3+ ), Y(V,P)O4:Eu 3+ (and / or Tb 3+ ), Lu3Al5O 12 :Ce 3+ (or Eu 3+ and / or Tb 3+ ), Y3Al5O 12 :Ce 3+ (or Eu 3+ and / or Tb 3+ ), BaMgAl 14 O 23 :Mn 2+ Mg(Al,Ga)2O4:Mn 2+ Zn2SiO4:Mn 2+ K2SiF6:Mn 4+ MgF2.GeO2:Mn 4+ This includes combinations thereof.

[0080] As described above, the first luminescent material may contain the luminescent nanoparticles of this invention.

[0081] The fluorescent material may be currently available on the market or may be synthesized, for example, as described in Riwotzki, K.; Meyssamy, H.; Kornowski, A.; Haase, M. J. Phys. Chem. B. 2000, 104, 2824-2828.

[0082] As is known to those skilled in the art, rare earth-doped fluorescent materials contain a host lattice doped with optically active ions.

[0083] The first luminescent material may have a suitable host lattice. The host lattice may be composed of, for example, oxides, fluorides, nitrides, borates, garnets, molybdates, phosphates, vanadates, chlorides, sulfides, selenides, silicates, aluminates, oxyfluorides, oxychlorides, oxynitrides,oxysulfides,oxyselenides,fluorochlorides,fluorosilicates and fluorobromides, or combinations thereof, or other inorganic host materials capable of incorporating optically active ions.

[0084] Preferably, the host lattice of the first luminescent material is an oxide, phosphate, vanadate or a combination thereof, more preferably selected from the group consisting of Y3Al5O 12 (YAG), Lu3Al5O 12 (LuAG), Y2O3, YVPO4, YVO4 or LaPO4 or combinations thereof. Preferably, the host lattice of the preferred first luminescent material is doped with one or more ions selected from the group consisting of Eu 3+ , Tb 3+ , Mn 2+ and Mn 4+ These ions provide good luminescence properties such as strong emission bands and / or emission bands in the red or green part of the visible spectrum.

[0085] Eu 3+ In the case of doping with Eu, the first luminescent material may have, for example, a host lattice doped at a doping rate of at least about 10%, more preferably at a doping rate of about 15% to about 80%. Tb 3+ In the case of doping with Tb, the first luminescent material may have, for example, a host lattice doped with Tb at a doping rate of at least about 15%, more preferably at a doping rate of about 30% to about 80% 3+ In the case of doping with Mn, the first luminescent material may have, for example, a host lattice doped at a doping rate of at least about 0.1 to 30%, most preferably at a doping rate of about 1 to 10%. Mn 4+ In the case of doping with Mn, the first luminescent material may have, for example, a host lattice doped at a doping rate of at least about 0.1 to 30%, most preferably at a doping rate of about 1 to 10%. 2+ In the case of doping with, the first luminescent material may have, for example, a host lattice doped at a doping rate of at least about 0.1 to 30%, most preferably at a doping rate of about 1 to 10%.

[0086] ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​), Ba3(PO4)2:Eu 3+ (or Tb 3+ ), Ba3Ca3(PO4)4:Eu 3+ (or Tb 3+ ), Ba3Gd(BO3)3:Eu 3+ (or Tb 3+ ), Ba3Gd2(BO3)4:Eu 3+ (or Tb 3+ ), Ba3La2(BO3)4:Eu 3+ (or Tb 3+ ), Ba3V2O8:Eu 3+ (or Tb 3+ ), Ba3Y2(BO3)4:Eu 3+ (or Tb 3+ ), BaB8O 13 :EU 3+ (or Tb 3+ ), BaBPO5:Eu 3+ (or Tb 3+ ), BaFCl:Eu 3+ (or Tb 3+ ),BaGd2O4:Eu 3+ (or Tb 3+ ), BaGd4Si5O 17 :Sm:Eu 3+ (or Tb 3+ ), BaGdB9O 16 :EU 3+ (or Tb 3+ ), BaLaB9O 16 :EU 3+ (or Tb 3+ ), BaSO4:Eu 3+ (or Tb 3+ ),BaY2F8:Yb:Eu 3+ (or Tb 3+ ), BaY2Si3O 10 :EU 3+ (or Tb 3+ ), BaYB9O 16 :EU 3+ (or Tb 3+ ), BaZr(BO3)2:Eu 3+ (or Tb 3+ ), BaZrO3:Eu 3+ (or Tb 3+ ), BaZrO3:Eu 3+ (or Tb3+ ), b-BaB2O4:Eu 3+ (or Tb 3+ ), B-Gd2O3:Eu 3+ (or Tb 3+ ), Ca2Al(AlSiO7):Eu 3+ (or Tb 3+ ), Ca2Gd2(GeO4)2O:Eu 3+ (or Tb 3+ ), Ca2Gd8(SiO4)6O2:Eu 3+ (or Tb 3+ ), Ca2Gd8Si6O 26 :EU 3+ (or Tb 3+ ), Ca2La8(SiO4)6O2:Eu 3+ (or Tb 3+ ), Ca3(BO3)2:Eu 3+ (or Tb 3+ ), Ca3Al2O6:Eu 3+ (or Tb 3+ ), Ca3Gd2(BO3)4:Eu 3+ (or Tb 3+ ), Ca3La2(BO3)4:Eu 3+ (or Tb 3+ ), Ca3Y2(BO3)4:Eu 3+ (or Tb 3+ ), Ca4GdO(BO3)3:Eu 3+ (or Tb 3+ ), Ca5(PO 11 3F:Eu 3+ (or Tb 3+ ), Ca5(PO4)3Br:Eu 3+ (or Tb 3+ ), Ca5(PO4)3F:(4f site):Eu 3+ (or Tb 3+ ), Ca5(PO4)3F:(6h site):Eu 3+ (or Tb 3+ ), Ca5(PO4)3OH:Eu 3+ (or Tb 3+ ), CaBPO5:Eu 3+ (or Tb 3+ ), CaF2:Eu 3+ (or Tb 3+ ), CaLaB7O 13:EU 3+ (or Tb 3+ ), calcite-CaCO3:Eu 3+ (or Tb 3+ ), CaO:Eu 3+ (or Tb 3+ ), CaSO4:Eu 3+ (or Tb 3+ ), CaYO(BO3):Eu 3+ (or Tb 3+ ), C-Gd2O3:Eu 3+ (or Tb 3+ ), C-Lu2O3:(C2):Eu 3+ (or Tb 3+ ), C-Lu2O3:(C3i):Eu 3+ (or Tb 3+ ),Cs2NaYF6:Tm:Eu 3+ (or Tb 3+ ), C-Sc2O3:Yb:Eu 3+ (or Tb 3+ ), C-Y2O3:Eu 3+ (or Tb 3+ ),EU 3+ (or Tb 3+ )[(ttfa)3(phen)]0:Eu 3+ (or Tb 3+ ), Gd 17.33 (BO3)4(B2O5)2O 16 :EU 3+ (or Tb 3+ ), Gd2BaZnO5:Eu 3+ (or Tb 3+ ), Gd2O2(SO4):Eu 3+ (or Tb 3+ ), Gd2P4O 13 :EU 3+ (or Tb 3+ ), Gd3O4Br:Eu 3+ (or Tb 3+ ), Gd3PO7:Eu 3+ (or Tb 3+ ), Gd3Te2Li3O 12 :EU 3+ (or Tb 3+ ), Gd8P2O 17 :EU 3+ (or Tb 3+ ), GdAl3 (BO3) 4:Eu 3+ (or Tb 3+ ), GdAlO3:Eu 3+ (or Tb 3+ ), GdAlO3:Eu 3+ (or Tb 3+ ), GdB3O6:Eu 3+ (or Tb 3+ ), GdBO3:Eu 3+ (or Tb 3+ ), GdGaO3:Eu 3+ (or Tb 3+ ), GdOBr:Eu 3+ (or Tb 3+ ), GdOCl:Eu 3+ (or Tb 3+ ), GdP3O9:Eu 3+ (or Tb 3+ ), GdPO4:Eu 3+ (or Tb 3+ ), I-CaB2O4:Eu 3+ (or Tb 3+ ), InBO3:Eu 3+ (or Tb 3+ ), I-SrB2O4:Eu 3+ (or Tb 3+ ), KCaGd(PO4)2:Eu 3+ (or Tb 3+ ), La 26 O 27 (BO3) 8:Eu 3+ (or Tb 3+ ), La2BaZnO5:Eu 3+ (or Tb 3+ ),La2Hf2O7:Eu 3+ (or Tb 3+ ), La2O2(SO4):Eu 3+ (or Tb 3+ ), La2O2S:Eu 3+ (or Tb 3+ ), La2W3O 12 :EU 3+ (or Tb 3+ ),La2Zr3(MoO4)9:Eu 3+ (or Tb 3+ ), La3TaO4Cl6:Eu 3+ (or Tb 3+),La3WO6Cl3:Eu 3+ (or Tb 3+ ), LaAlO3:Eu 3+ (or Tb 3+ ), LaB3O6:Eu 3+ (or Tb 3+ ), LaBO3:Eu 3+ (or Tb 3+ ), LaF3:Eu 3+ (or Tb 3+ ), LaGaO3:Eu 3+ (or Tb 3+ ), LaMgB5O 10 :EU 3+ (or Tb 3+ ), LaOBr:Eu 3+ (or Tb 3+ ), LaOCl:Eu 3+ (or Tb 3+ ), LaOF:Eu 3+ (or Tb 3+ ), LaOI:Eu 3+ (or Tb 3+ ),LaP3O9:Eu 3+ (or Tb 3+ ), LaPO4:Eu 3+ (or Tb 3+ ), LaYO3:Eu 3+ (or Tb 3+ ), Li2Lu5O4(BO3)3:Eu 3+ (or Tb 3+ ), Li3Ba2La3(MoO4)8:Eu 3+ (or Tb 3+ ), Li3La2(BO3)3:Eu 3+ (or Tb 3+ ), Li6Gd(BO3)3:Eu 3+ (or Tb 3+ ), Li6Y(BO3)3:Eu 3+ (or Tb 3+ ), LiCaAlF6:Eu 3+ (or Tb 3+ ), LiEu 3+ (or Tb 3+ ), Mo2O8:Eu 3+ (or Tb 3+ ), LiGd6O5(BO3)3:Eu 3+(or Tb 3+ ), LiGdF4:Eu 3+ (or Tb 3+ ), LiGdGeO4:Eu 3+ (or Tb 3+ ), LiGdO2:Eu 3+ (or Tb 3+ ), LiGdSiO4:Eu 3+ (or Tb 3+ ), LiLa2O2BO3:Eu 3+ (or Tb 3+ ), LiLaGeO4:Eu 3+ (or Tb 3+ ), LiLaO2:Eu 3+ (or Tb 3+ ), LiLaP4O 12 :EU 3+ (or Tb 3+ ), LiLaSiO4:Eu 3+ (or Tb 3+ ), LiLuGeO4:Eu 3+ (or Tb 3+ ), LiLuO2:Eu 3+ (or Tb 3+ ), LiLuSiO4:Eu 3+ (or Tb 3+ ), LiScO2:Eu 3+ (or Tb 3+ ), LiSr2YO4:Eu 3+ (or Tb 3+ ), LiSrAlF6:Eu 3+ (or Tb 3+ ), LiY6O5(BO3)3:Eu 3+ (or Tb 3+ ), LiYF4:Eu 3+ (or Tb 3+ ), LiYGeO4:Eu 3+ (or Tb 3+ ), LiYO2:Eu 3+ (or Tb 3+ ), LiYSiO4:Eu 3+ (or Tb 3+ ), Lu2O2(SO4):Eu 3+ (or Tb 3+ ), Lu2Si2O7:Eu 3+ (or Tb 3+ ), Lu3Al5O12 :EU 3+ (or Tb 3+ ), Lu3Al5O 12 :Yb:Eu 3+ (or Tb 3+ ), LuBO3:Eu 3+ (or Tb 3+ ), LuBO3 (calcite): Eu 3+ (or Tb 3+ ), LuOCl:Eu 3+ (or Tb 3+ ), LuPO4:Eu 3+ (or Tb 3+ ), Mg2Gd8(SiO4)6O2:Eu 3+ (or Tb 3+ ), Mg2La8(SiO4)6O2:Eu 3+ (or Tb 3+ ), MgO:Eu 3+ (or Tb 3+ ), MgSiO3:Eu 3+ (or Tb 3+ ), Na3YSi3O9:Eu 3+ (or Tb 3+ ), Na6Gd(BO3)3:Eu 3+ (or Tb 3+ ),NaGdGeO4:Eu 3+ (or Tb 3+ ), NaGdO2:Eu 3+ (or Tb 3+ ), NaGdSiO4:Eu 3+ (or Tb 3+ ), NaLaGeO4:Eu 3+ (or Tb 3+ ), NaLaO2:Eu 3+ (or Tb 3+ ), NaLaSiO4:Eu 3+ (or Tb 3+ ),NaLuGeO4:Eu 3+ (or Tb 3+ ), NaLuSiO4:Eu 3+ (or Tb 3+ ), NaScO2:Eu 3+ (or Tb 3+ ), NaSrLa(VO4)2:Eu 3+ (or Tb 3+ ), NaYGeO4:Eu3+ (or Tb 3+ ), NaYSiO4:Eu 3+ (or Tb 3+ ), ScBO3:Eu 3+ (or Tb 3+ ),ScOCl:Eu 3+ (or Tb 3+ ), ScPO4:Eu 3+ (or Tb 3+ ), Sr2B2O5:Eu 3+ (or Tb 3+ ), Sr2Gd8(SiO4)6O2:Eu 3+ (or Tb 3+ ), Sr2La2Zn2O7:Eu 3+ (or Tb 3+ ), Sr2La2Zn2O7:Eu 3+ (or Tb 3+ ), Sr2LaAlO5:Eu 3+ (or Tb 3+ ), Sr3(BO3)2:Eu 3+ (or Tb 3+ ), Sr3(PO4)2:Eu 3+ (or Tb 3+ ), Sr3(PO4)2:Sm:Eu 3+ (or Tb 3+ ), Sr3Gd2(BO3)4:Eu 3+ (or Tb 3+ ), Sr3La2(BO3)4:Eu 3+ (or Tb 3+ ), Sr3La6(SiO4)6:Eu 3+ (or Tb 3+ ), Sr3Y2(BO3)4:Eu 3+ (or Tb 3+ ), Sr5(PO4)3F:Eu 3+ (or Tb 3+ ), Sr9Ln(VO4)7:Eu 3+ (or Tb 3+ ), SrAl2B2O7:Eu 3+ (or Tb 3+ ), SrB4O7:Eu 3+ (or Tb 3+ ), SrB6O 10 :EU 3+ (or Tb 3+), SrCO3:Eu 3+ (or Tb 3+ ), SrGdAlO4:Eu 3+ (or Tb 3+ ), SrHfO3:Tm:Eu 3+ (or Tb 3+ ), SrLa2BeO5:(4c):Eu 3+ (or Tb 3+ ), SrLa2BeO5:(8d):Eu 3+ (or Tb 3+ ), SrLaAlO4:Eu 3+ (or Tb 3+ ), SrLaGa3O7:Eu 3+ (or Tb 3+ ), SrLaO(BO3):Eu 3+ (or Tb 3+ ), SrO:Eu 3+ (or Tb 3+ ), SrY2O4:(Sr site):Eu 3+ (or Tb 3+ ), SrY2O4:(Y site 1):Eu 3+ (or Tb 3+ ), SrY2O4:(Y site 2):Eu 3+ (or Tb 3+ ), Tb2Mo3O 12 :EU 3+ (or Tb 3+ ), Tb2W3O 12 :EU 3+ (or Tb 3+ ), TbBO3:Eu 3+ (or Tb 3+ ), ThO2:Eu 3+ (or Tb 3+ ), X1-Gd2SiO5:Eu 3+ (or Tb 3+ ), X1-Y2SiO5:Eu 3+ (or Tb 3+ ), X2-Y2SiO5:Eu 3+ (or Tb 3+ ), Y 17.33 (BO3)4(B2O5)2O 16 :EU 3+ (or Tb 3+ ),Y2Ge2O7:Eu 3+ (or Tb 3+),Y2GeO5:Eu 3+ (or Tb 3+ ), Y2O2(SO4):Eu 3+ (or Tb 3+ ), Y2O2S:Eu 3+ (or Tb 3+ ), Y2O2S:Eu 3+ (or Tb 3+ ), Y2O3:Eu 3+ (or Tb 3+ ), Y2P4O 13 :EU 3+ (or Tb 3+ ), Y2Si2O7:Eu 3+ (or Tb 3+ ), Y2SiO5:Eu 3+ (or Tb 3+ ), Y3Al5O 12 :EU 3+ (or Tb 3+ ), Y3O4Br:Eu 3+ (or Tb 3+ ), Y3O4Cl:Eu 3+ (or Tb 3+ ), Y3PO7:Eu 3+ (or Tb 3+ ),Y4GeO8:Eu 3+ (or Tb 3+ ), Y8P2O 17 :EU 3+ (or Tb 3+ ), YAl3(BO3)4:Eu 3+ (or Tb 3+ ), YAlO3:Eu 3+ (or Tb 3+ ), YBO3:Eu 3+ (or Tb 3+ ), YbOBr:Yb:Eu 3+ (or Tb 3+ ), YF3:Eu 3+ (or Tb 3+ ), YOBr:Eu 3+ (or Tb 3+ ), YOCl:Eu 3+ (or Tb 3+ ), YOCl:Eu 3+ (or Tb 3+ ), YOF:Eu 3+ (or Tb 3+ ) YOF:Eu 3+ (or Tb 3+ ) YP3O9:Eu 3+ (or Tb 3+ ) YPO4:Eu 3+ (or Tb 3+ ) YTaO4:Eu 3+ (or Tb 3+ ) YVO4:Eu 3+ (or Tb 3+ ) ZrP2O7:Eu 3+ (or Tb 3+ ) Y3Al5O 12 :Ce 3+ Lu3Al5O 12 :Ce 3+ It is selected from the group consisting of or a mixture thereof.

[0087] The notation ":Eu 3+ " (":Tb 3+ ", ":Ce 3+ ", ":Mn 2+ " or ":Mn 4+ ")", when it indicates that the host lattice is doped with Eu 3+ (Tb 3+ , Ce 3+ , Mn 2+ or Mn 4+ ), will be understood by those skilled in the art.

[0088] The second luminescent material The second luminescent material preferably contains garnet nanoparticles of (A 1-x B x )3(C 1-y D y )5O 12 In such a composition, B is preferably cerium and / or terbium.

[0089] As described above, the first luminescent material may contain the luminescent nanoparticles of the present invention. In a composition in which the first luminescent material contains the nanoparticles of the present invention, the second luminescent material is preferably as described below.

[0090] A suitable inorganic light-emitting material may be used as the second light-emitting material. The second material can absorb light in a second wavelength range. The second wavelength range may be any wavelength range of interest.

[0091] Preferably, the second light-emitting material has one or more excitation bands in the wavelength range of 380 to 580 nm, and more preferably, the second light-emitting material has one or more excitation bands in UV-A (315 to 400 nm), violet (400 to 440 nm), blue (440 to 480 nm), or green (510 to 560 nm), most preferably in blue (440 to 480 nm). LEDs based on (Al,In,Ga)N generate efficient "pump" light in the violet to blue wavelength range (approximately 400 nm to approximately 480 nm). An example of a blue excitation material is CaAlSiN3:Eu 2+ Y3Al5O 12 :Ce 3+ These are CsPbBr3, CdSe, and InP.

[0092] In another aspect of this invention, the second light-emitting material is a material having one or more excitation bands of 700-1400 nm (IR-A), 580-600 nm (amber and / or orange), 560-580 nm (yellow), 510-560 nm (green), 480-510 nm (cyan), 440-480 nm (blue), 400-440 nm (violet), 315-400 nm (UV-A) and / or 280-315 nm (UV-B).

[0093] In another preferred embodiment, the host lattice of the second luminescent material is garnet, fluoride, silicate, phosphate, or nitride, more preferably Y3Al5O 12 (YAG), Lu3Al5O 12 (LuAG), MgF2, CaF2, Sr2SiO4, Ba2SiO4, Ca2MgSi2O7, LiSrPO4, CaAlSiN3, or combinations thereof are selected from the group. Preferably, the host lattice of the preferred second luminescent material is Eu 2+ Pb 2+ , Bi 3+ and Ce 3+It is doped with one or more ions selected from the group consisting of Tb 3+ EU combined with 2+ or Ce 3+ And most preferably Tb 3+ Ce combined with 3+ That is the case.

[0094] Preferably, the host lattice of the second light-emitting material or its precursor is garnet, for example, Y3Al5O 12 (YAG) or Lu3Al5O 12 (LuAG) or a combination thereof. Most preferably, the host lattice is Y3Al5O 12 (YAG) or Lu3Al5O 12 (LuAG) or a combination thereof is selected from the group, and the dopant is Tb as needed. 3+ Combined with Ce 3+ Includes.

[0095] Preferably, Ce 3+ In the case of doping by , the second luminescent material has a host lattice doped with a doping rate of 0.05 to 5%, more preferably 0.1 to 4%.

[0096] Preferably, the first luminescent material comprises Y2O3:RE (wherein RE is europium(III)), and the second luminescent material comprises the rare earth metal-doped garnet nanoparticles of this invention, wherein the rare earth metal is cerium and / or terbium. More preferably, the Y2O3:RE material is provided as nanoparticles.

[0097] In a preferred embodiment, the first light-emitting material comprises rare-earth metal-doped nanoparticles in which the rare-earth metal is europium(III), and the second light-emitting material comprises (A) the present invention. 1-x B x )3(C 1-y D y )5O 12 It contains garnet nanoparticles (wherein B is cerium(III) and / or terbium(III)).

[0098] Furthermore, this invention relates to a light-emitting device comprising light-emitting nanoparticles that can be obtained by the method of this invention. Preferably, the light-emitting device further comprises an excitation source for a light-emitting material, for example, a second light-emitting material. Preferably, the excitation source is a UV-A, purple, or blue light-emitting material that emits light of 315-400 nm (UV-A), 400-440 nm (violet), or 440-480 nm (blue), more preferably 430-465 nm, relative to the light-emitting material.

[0099] The light-emitting device comprises a blue light-emitting LED and the (A) of this invention deposited on the LED chip. 1-x B x )3(C 1-y D y )5O 12 The luminescent nanoparticles may consist of garnet nanoparticles or a luminescent composition. The luminescent nanoparticles of this invention may be deposited on a blue LED chip and then bonded to a polymer or silicone slurry that is subsequently cured.

[0100] Furthermore, this invention relates to a lighting system including the light-emitting device of this invention. Preferably, the lighting system is selected from the group consisting of lamps or luminaires, office lighting systems, home systems, store lighting systems, residential lighting systems, accent lighting systems, spot lighting systems, theater lighting systems, fiber optic systems, projection systems, self-illuminating display systems, pixel display systems, segment display systems, warning display systems, medical lighting systems, signage display systems, decorative lighting systems, portable systems, automotive systems, and greenhouse lighting systems.

[0101] Furthermore, this invention is (A 1-x B x )3(C 1-y D y )5O 12This invention relates to the use of luminescent materials or luminescent compositions of this invention that contain garnet nanoparticles as tagants. A tagant is a marker added to a material to enable various tests. The overall excitation / emission spectrum of the luminescent materials and / or luminescent compositions of this invention may have unique characteristics compared to conventional methods and therefore may be useful as anti-counterfeiting tagants. For example, U.S. Patent No. 7,667,828 discloses a tagging system that includes tagants of different types. [Examples]

[0102] Comparative Example 1 The YAG:1.5%Ce precursor was synthesized by precipitation according to the Journal of Materials Research, 2018, 53, 15196-15203. A 0.5M aqueous solution of K2SO4 was prepared. The YAG:Ce precursor and the K2SO4 solution were mixed to obtain a dispersion with a YAG:K2SO4 weight ratio of 1:15. Mixing was promoted by sonication in an ultrasonic bath for 30 minutes. Igepal® CO-520 was added in a volume ratio of 1:4 to the Igepal®:K2SO4 solution. Cyclohexane was added in a volume ratio of 2.5:1 to the cyclohexane:K2SO4 solution. The mixture was mixed in an ultrasonic bath for 30 minutes. Acetone was added in a volume ratio of 1:8 to the acetone:reaction mixture. The mixture was centrifuged, washed with acetone, and the precipitate was dried.

[0103] The resulting dried powder was heated in an oven at 1020°C for 2 hours. The annealed sample was washed several times with water to remove K2SO4.

[0104] The emission of YAG:Ce was measured and is shown in Figure 1. European Patent Application Publication No. 3789468 discloses the PL of YAG:Ce after annealing in air with a protective salt, compared to the PL spectrum of a sample before annealing. The precursor sample before calcination is essentially amorphous and therefore shows no emission. The annealed sample shows a broad yellow emission. TEM analysis showed that sintering was minimized after annealing with a protective salt. The presence of the salt during annealing allows for increased emission without sintering the particles.

[0105] Comparative Example 2 YAG:1%Ce nanoparticles were prepared by glycothermal reaction according to the method disclosed in J. Mater. Chem. C, 2017, 5, 12561. 1,4-butanediol and diethylene glycol were used as solvents in a volume ratio of 85:15. The organometallic salt precursors were pre-dried using the P2O5 scavenging method disclosed in J. Mater. Chem. C, 2017, 5, 12561. The reaction mixture was then mixed and autoclaved at 300°C for at least 10 minutes. This method yielded nanoparticles with individual sizes less than 10 nm. 300 mg of YAG:Ce nanoparticles were dispersed in 5 ml of 0.5 M K2SO4 aqueous solution. The solution was then sonicated for 30 minutes. 25 ml of Igepal® CO-520 was added to a separate beaker (i.e., the volume ratio of Igepal®:K2SO4 solution was 5:1). 250 ml of cyclohexane was added to a beaker containing Igepal®CO-520 (the volume ratio of the cyclohexane:K2SO4 solution was 50:1). The mixture of Igepal®CO-520 and cyclohexane was stirred for 10 minutes. Then, the YAG:K2SO4 solution was added dropwise to the Igepal®CO-520-cyclohexane mixture while stirring at a constant rate. The mixture was mixed in an ultrasonic bath for 30 minutes. Acetone was added in an acetone:mixture volume ratio of 1:15. The mixture was centrifuged and the precipitate was dried.

[0106] The resulting dried powder was heated in an oven at 1000°C for 2 hours. The powder was washed with water to remove K2SO4.

[0107] Figure 2 shows the luminescence intensity of the annealed sample.

[0108] Comparative Example 3 YAG:1%Ce nanoparticles were prepared by glycothermal reaction according to the method disclosed in J. Mater. Chem. C, 2017, 5, 12561. 1,4-butanediol and diethylene glycol were used as solvents in a volume ratio of 85:15. The organometallic salt precursors were pre-dried using the P2O5 scavenging method disclosed in J. Mater. Chem. C, 2017, 5, 12561. The reaction mixture was then mixed and autoclaved at 300°C for at least 10 minutes. This method yielded nanoparticles with individual sizes less than 10 nm. 300 mg of YAG:Ce nanoparticles were dispersed in 5 ml of 0.5 M K2SO4 aqueous solution. The solution was then sonicated for 30 minutes. 25 ml of Igepal® CO-520 was added to a separate beaker (i.e., the volume ratio of Igepal®:K2SO4 solution was 5:1). 250 ml of cyclohexane was added to a beaker of Igepal® CO-520 (i.e., the volume ratio of the cyclohexane:K2SO4 solution was 50:1). The Igepal® CO-520 and cyclohexane solution was stirred for 10 minutes. Then, the YAG:K2SO4 solution was added dropwise to the Igepal® CO-520-cyclohexane solution while stirring at a constant rate. The mixture was mixed in an ultrasonic bath for 30 minutes. Acetone was added in an acetone:mixture volume ratio of 1:15. The mixture was centrifuged and the precipitate was dried.

[0109] The resulting dried powder was heated in an oven at 900°C for 2 hours. The powder was washed with water to remove K2SO4.

[0110] Figure 3 shows the luminescence intensity of the annealed sample.

[0111] Comparative Example 4 YAG:1%Ce nanoparticles were prepared by glycothermal chromatography according to the method disclosed in J. Mater. Chem. C, 2017, 5, 12561. 1,4-butanediol and diethylene glycol were used as solvents in a volume ratio of 85:15. The organometallic salt precursor was pre-dried using the P2O5 scavenging method disclosed in J. Mater. Chem. C, 2017, 5, 12561. The reaction mixture was then mixed and autoclaved at 300°C for at least 10 minutes. This method yielded nanoparticles with individual sizes less than 10 nm. 300 mg of YAG:Ce nanoparticles were dispersed in 5 ml of 0.5 M aqueous K2SO4 solution. The solution was then sonicated for 30 minutes. Acetone was added in a volume ratio of acetone:mixture of 5:1. The mixture was centrifuged, and the precipitate was dried.

[0112] The obtained dried powder was heated in a reducing atmosphere at 800°C in an oven using a carbon double crucible apparatus for 8 hours. The YAG:Ce-K2SO4 salt mixture was placed in a crucible. This crucible was placed in a larger crucible partially filled with carbon powder. The larger crucible was then covered. This double crucible was heated in an oven at 800°C for 8 hours. The powder was washed with water to remove the K2SO4.

[0113] In this comparative example, the first annealing step was omitted. Due to the lower annealing temperature, the particle size was smaller, and the PL strength was weaker than in the example where annealing was performed twice.

[0114] Example 1 The YAG:1.5%Ce precursor was synthesized by precipitation (Journal of Materials Research, 2018, 53, 15196-15203). A 0.5M aqueous solution of K2SO4 was prepared. The YAG:1.5%Ce precursor and the K2SO4 solution were mixed to obtain a dispersion with a YAG:K2SO4 weight ratio of 1:15. Mixing was promoted by sonication in an ultrasonic bath for 30 minutes. Igepal® CO-520 was added in a volume ratio of 1:4 to the Igepal®:K2SO4 solution. Cyclohexane was added in a volume ratio of 2.5:1 to the cyclohexane:K2SO4 solution. The mixture was mixed in an ultrasonic bath for 30 minutes. Acetone was added in a volume ratio of 1:8 to the acetone:reaction mixture. The mixture was centrifuged, washed with acetone, and the precipitate was dried. The resulting dried powder was heated in an oven at 1020°C in air for 2 hours.

[0115] Following the initial annealing, a second annealing was performed in a reducing atmosphere using a carbon double crucible apparatus. The YAG:1.5%Ce-K2SO4 salt mixture that had been annealed in the first step was placed in a crucible. This crucible was then placed in a larger crucible partially filled with carbon powder. The larger crucible was then covered. This double crucible was heated in an 800°C oven for 4 hours. The annealed sample was washed several times with water to remove the K2SO4.

[0116] The luminescence intensity of samples annealed in air and in a reducing atmosphere is improved compared to samples annealed in air only (Figure 1). The TEM image in Figure 4 shows that sintering was minimized after two annealing passes using a protective salt. Since the second annealing pass was performed at a lower temperature, its effect on particle morphology is negligible.

[0117] In contrast to the results of Journal of Materials Research, 2018, 53, 15196-15203, the results of using the precipitation method for YAG synthesis (Comparative Example 1, Example 1, etc.) consistently yielded networked nanoparticles, as shown in the representative example in Figure 4. While Journal of Materials Research, 2018, 53, 15196-15203 suggests very small, spherical nanoparticles with individual sizes less than 10 nm, the results were not reproducible.

[0118] Example 2 YAG:1%Ce nanoparticles were prepared by glycothermal reaction according to the method disclosed in J. Mater. Chem. C, 2017, 5, 12561. 1,4-butanediol and diethylene glycol were used as solvents in a volume ratio of 85:15. The organometallic salt precursors were pre-dried using the P2O5 scavenging method disclosed in J. Mater. Chem. C, 2017, 5, 12561. The reaction mixture was then mixed and autoclaved at 300°C for at least 10 minutes. This method yielded nanoparticles with individual sizes less than 10 nm. 300 mg of YAG:Ce nanoparticles were dispersed in 5 ml of 0.5 M K2SO4 aqueous solution. The solution was then sonicated for 30 minutes. 25 ml of Igepal® CO-520 was added to a separate beaker (i.e., the volume ratio of Igepal®:K2SO4 solution was 5:1). Cyclohexane was added to a beaker of Igepal®CO-520 in a cyclohexane:K2SO4 solution in a volume ratio of 50:1. The mixture of Igepal®CO-520 and cyclohexane was stirred for 10 minutes. Then, a YAG:K2SO4 solution was added dropwise to the Igepal®CO-520-cyclohexane mixture while stirring at a constant rate. The mixture was mixed in an ultrasonic bath for 30 minutes. Acetone was added in an acetone:mixture volume ratio of 1:15. The mixture was centrifuged and the precipitate was dried.

[0119] The resulting dried powder was heated in an oven at 1000°C in air for 2 hours. Following the first annealing, a second annealing was performed in a reducing atmosphere using a carbon double crucible apparatus. The first annealed YAG:Ce-K2SO4 salt mixture was placed in a crucible. This crucible was placed in a larger crucible partially filled with carbon powder. The larger crucible was then covered. This double crucible was heated in an oven at 800°C for 8 hours. The powder was washed with water to remove K2SO4.

[0120] Figure 2 shows the emission intensity of the annealed sample. Electron microscopy analysis of the annealed sample reveals spherical nanoparticles with an average particle size of approximately 20 nm (Figure 5).

[0121] Example 3 YAG:1%Ce nanoparticles were prepared by glycothermal reaction according to the method disclosed in J. Mater. Chem. C, 2017, 5, 12561. 1,4-butanediol and diethylene glycol were used as solvents in a volume ratio of 85:15. The organometallic salt precursors were pre-dried using the P2O5 scavenging method disclosed in J. Mater. Chem. C, 2017, 5, 12561. The reaction mixture was then mixed and autoclaved at 300°C for at least 10 minutes. This method yielded nanoparticles with individual sizes less than 10 nm. 300 mg of YAG:Ce nanoparticles were dispersed in 5 ml of 0.5 M K2SO4 aqueous solution. The solution was then sonicated for 30 minutes. 25 ml of Igepal® CO-520 was added to a separate beaker (i.e., the volume ratio of Igepal®:K2SO4 solution was 5:1). Cyclohexane was added to a beaker of Igepal®CO-520 in a cyclohexane:K2SO4 solution in a volume ratio of 50:1. The mixture of Igepal®CO-520 and cyclohexane was stirred for 10 minutes. Then, a YAG:K2SO4 solution was added dropwise to the Igepal®CO-520-cyclohexane mixture while stirring at a constant rate. The mixture was mixed in an ultrasonic bath for 30 minutes. Acetone was added in an acetone:mixture volume ratio of 1:15. The mixture was centrifuged and the precipitate was dried.

[0122] The resulting dried powder was heated in an oven at 900°C in air for 2 hours. Following the first annealing, a second annealing was performed in a reducing atmosphere using a carbon double crucible apparatus. The first annealed YAG:Ce-K2SO4 salt mixture was placed in a crucible. This crucible was placed in a larger crucible partially filled with carbon powder. The larger crucible was then covered. This double crucible was heated in an oven at 800°C for 8 hours. The powder was washed with water to remove K2SO4.

[0123] Figure 3 shows the luminescence intensity of the annealed sample.

[0124] Example 4 YAG:3%Ce nanoparticles were prepared by glycothermal chromatography according to the method disclosed in J. Mater. Chem. C, 2017, 5, 12561. 1,4-butanediol and diethylene glycol were used as solvents in a volume ratio of 85:15. The organometallic salt precursor was pre-dried using the P2O5 scavenging method disclosed in J. Mater. Chem. C, 2017, 5, 12561. The reaction mixture was then mixed and autoclaved at 300°C for at least 10 minutes. This method yielded nanoparticles with individual sizes less than 10 nm. 300 mg of YAG:Ce nanoparticles were dispersed in 5 ml of 0.5 M K2SO4 aqueous solution. The solution was then sonicated for 30 minutes. Acetone was added in a volume ratio of acetone:mixture of 5:1. The mixture was centrifuged, and the precipitate was dried.

[0125] The resulting dried powder was heated in an oven at 1000°C in air for 2 hours. Following the first annealing, a second annealing was performed in a reducing atmosphere using a carbon double crucible apparatus. The first annealed YAG:Ce-K2SO4 salt mixture was placed in a crucible. This crucible was placed in a larger crucible partially filled with carbon powder. The larger crucible was then covered. This double crucible was heated in an oven at 800°C for 8 hours. The powder was washed with water to remove K2SO4.

[0126] Figure 6 shows the emission and excitation spectra of the annealed samples. The average particle size is slightly larger for nanoparticles annealed with a salt matrix alone (Example 4) compared to nanoparticles annealed using a microemulsion-based salt matrix calcined under the same conditions (Example 2). Figure 7 shows the TEM of the nanoparticles, suggesting that the particles are slightly larger.

[0127] Example 5 and Comparative Example 5 YAG:0.5%Ce precursor particles were synthesized by precipitation according to the Journal of Materials Research, 2018, 53, 15196-15203.

[0128] A 0.5 M aqueous solution of K2SO4 was prepared. Nano YAG precursor particles and the K2SO4 solution were mixed to obtain a dispersion with a YAG precursor:K2SO4 weight ratio of 1:10. Mixing was promoted by sonication in an ultrasonic bath for 30 minutes. Acetone was added in a volume ratio of acetone:reaction mixture of 1:8. The mixture was centrifuged, washed with acetone, and the precipitate was dried.

[0129] Example 5: The sample was annealed in air at 1025°C for 2 hours, and then annealed in a reducing atmosphere containing carbon monoxide at 800°C for 8 hours using a carbon-containing double crucible apparatus.

[0130] Comparative Example 5: The sample was annealed in air at 1025°C for 2 hours.

[0131] The nanoparticles were washed several times with water to remove K2SO4 and dried at 105°C. The luminescence of the samples from Comparative Example 5 and Example 5 was measured. Comparative Example 5 (single-step annealing sample) showed broad yellow luminescence, while Example 5 (two-step annealing sample) showed improved luminescence characteristics. The PLQY of Example 5 improved to approximately 80-85%. The salt matrix avoids sintering during heat treatment.

[0132] Example 6 and Comparative Example 6 YAG:0.5%Ce nanoparticles were synthesized according to the method disclosed in J. Mater. Chem. C, 2017, 5, 12561.

[0133] A 0.5 M aqueous solution of K2SO4 was prepared. YAG:Ce nanoparticles and the K2SO4 solution were mixed to obtain a dispersion with a YAG:K2SO4 weight ratio of 1:10. Mixing was promoted by sonication in an ultrasonic bath for 30 minutes. Acetone was added in a volume ratio of acetone:reaction mixture of 1:8. The mixture was centrifuged, washed with acetone, and the precipitate was dried.

[0134] Example 6: The sample was annealed in air at 1025°C for 2 hours, and then annealed in a reducing atmosphere containing carbon monoxide at 800°C for 8 hours using a carbon-containing double crucible apparatus.

[0135] Comparative Example 6: The sample was annealed in air at 1025°C for 2 hours.

[0136] The nanoparticles were washed several times with water to remove K2SO4 and dried at 105°C. The luminescence of the samples was measured. The PLQY of Comparative Example 6 (single-step annealing sample in air) was approximately 70%. The PLQY of Example 6 (two-step annealing sample) improved to approximately 70-80%. The salt matrix prevents sintering during the heat treatment.

Claims

1. (i) A step of providing a mixture of (a) a salt and (b) luminescent nanoparticles or their precursors. Here, the light-emitting nanoparticles are (A １－ｘ B ｘ ) ３ (C １－ｙ D ｙ ) ５ O １２ Garnet nanoparticles (wherein A consists of one or more of yttrium, lutetium, and gadolinium; B consists of one or more rare earth elements; C consists of one or more of aluminum, gallium, and scandium; D consists of one or more transition metal ions; x is between 0 and 1; y is between 0 and 1; and x + y is greater than 0). (ii) A step of heating the mixture at a first temperature for a first time, Here, the first temperature is 800°C or higher, the first time is 10 minutes or more, and (iii) A step of heating the mixture in a reducing atmosphere at a second temperature for a second time. Here, the second temperature is 500°C or higher, and the second time is 1 hour or longer. A method for processing luminescent nanoparticles or their precursors, including the aforementioned.

2. The method according to claim 1, wherein B is made of cerium and C is made of aluminum.

3. The luminescent nanoparticles are obtained by a solvothermal method, preferably a glycothermal method, according to any one of the preceding claims.

4. The first temperature is 900°C or higher, preferably 1500°C or lower, more preferably 1250°C or lower, and / or The first time is 10 minutes or more, preferably 1 hour or more, preferably 8 hours or less, more preferably 5 hours or less, and most preferably 3 hours or less, and, Preferably, the step of heating the mixture at a first temperature for a first time is carried out in a gaseous state, where the gaseous state is air or an inert gas. The method according to any one of the preceding claims.

5. The reducing atmosphere contains carbon monoxide. The second temperature is 600°C or higher, preferably 700°C or higher, preferably 1050°C or lower, more preferably 900°C or lower, and / or The second time is 2 hours or more, preferably 5 hours or more, preferably 7 hours or more, and preferably 12 hours or less, more preferably 9 hours or less. The method according to any one of the preceding claims.

6. The method according to claim 5, wherein heating under a reducing atmosphere is carried out by placing the mixture in a first crucible, placing the first crucible in a second crucible and sealing it, and further adding a carbon source to the second crucible.

7. The melting point of the salt is 800°C or higher, preferably 1000°C or higher, and / or The salt contains Se as an anion ２－ S ２－ Cl － F － Br － I － SO ４ ２－ PO ４ ３－ or NO ３ － or a combination thereof, and contains H as a cation ＋ Li ＋ Na ＋ Al ３＋ Ba ２＋ K ＋ Be ２＋ Ca ２＋ Mg ２＋ or Sr ２＋ or a combination thereof More preferably, the salt is K ２ SO ４ That is, The method according to any one of the preceding claims.

8. The method according to any one of the preceding claims, further comprising the step (iv) of removing the salt from the mixture after step (iii), preferably the removal comprising contacting the mixture with a solvent, more preferably the solvent being water.

9. This can be obtained by the method of any of the prior claims (A １－ｘ B ｘ ) ３ (C １－ｙ D ｙ ) ５ O １２ A luminescent nanoparticle that is a garnet nanoparticle (wherein A is composed of one or more of yttrium, lutetium, and gadolinium; B is composed of one or more rare earth elements; C is composed of one or more of aluminum, gallium, and scandium; D is composed of one or more transition metal ions; x is between 0 and 1; y is between 0 and 1; and x + y is greater than 0), The aforementioned light-emitting nanoparticles are - BET surface area is 10 m² ２ D exceeding / g, or measured by a transmission electron microscope (TEM) ５０ The wavelength is 0.5 nm to 100 nm, more preferably 5 nm to 50 nm. - The photostable during storage is such that the luminescence intensity after two weeks of storage in a non-inert atmosphere is at least 80% of the initial luminescence intensity. - Strength 0.1W / cm ２ When irradiated with 450 nm light, it exhibits photostability such that at least 80% of the initial emission intensity remains after 10 hours, and preferably at least 80% remains after 15 hours. Luminescent nanoparticles.

10. B consists of at least Ce, and the nanoparticles are - The emission quantum yield exceeds 25%, preferably exceeds 30%. - The peak ratio in the excitation spectra (455 nm and 380 nm) exceeds 20. The light-emitting nanoparticle according to claim 9.

11. A consists of at least one selected from the group consisting of yttrium and lutetium, B consists of at least one of cerium, terbium and europium, preferably C is aluminum, and B is cerium, europium, terbium, or a combination of terbium and europium. - If B consists of cerium, the molar concentration of cerium relative to the total of A and B is 0.05 to 5%. - If B consists of europium, the molar concentration of europium relative to the sum of A and B is 0.1 to 20%. - If B consists of terbium, the molar concentration of terbium relative to the sum of A and B is 20-100%. The light-emitting nanoparticle according to claim 9 or 10.

12. A luminescent composition containing luminescent nanoparticles according to any one of claims 9 to 11, or luminescent nanoparticles obtainable by the method described in claims 1 to 8, wherein the luminescent composition preferably contains at least 800 ppm of one or more selected from the group Li, Na, Ba, K, Be, Ca, Mg, or S, and at least 800 ppm of one or more selected from the group Se, S, Cl, F, Br, I, P, or N.

13. The material comprises a first light-emitting material and a second light-emitting material, wherein at least one of the first light-emitting material and the second light-emitting material comprises light-emitting nanoparticles according to any one of claims 9 to 11. Preferably, the first light-emitting material is capable of emitting light in a first wavelength range, and the second light-emitting material is capable of absorbing light in a second wavelength range and has an emission spectrum that at least partially overlaps with one or more excitation bands of the first light-emitting material. More preferably, the first light-emitting material and the second light-emitting material are arranged relative to each other to enable non-radiative energy transfer from the second light-emitting material to the first light-emitting material. More preferably, both the first light-emitting material and the second light-emitting material include light-emitting nanoparticles according to any one of claims 9 to 11. The light-emitting composition according to claim 12.

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