Composite light emitting particles

Abstract

The present invention provides a composite luminescent particle comprising (i) a first luminescent material which is a rare earth, s2 configuration ion or transition metal doped phosphorescent material, (ii) a second luminescent material which is a rare earth, s2 configuration ion or transition metal doped phosphorescent material, and further comprising (iii) a coating of an oxide material having a melting point of 700 DEG C or higher, wherein the oxide material is selected from the group consisting of silicon oxide, aluminum oxide, phosphate or magnesium oxide, and wherein the composite luminescent particle has a D50 value > = 1 nm and < = 100 [mu] m, as measured using transmission electron microscopy (TEM), and a method for obtaining such particles.

Description

Technical Field

[0001] The present invention relates to composite luminescent particles. The present invention also relates to methods for making composite luminescent particles. The present invention also relates to luminescent compositions comprising coated luminescent particles, and methods for making said luminescent compositions. The present invention also relates to devices comprising the composite luminescent particles of the present invention or the luminescent compositions of the present invention. Background Art

[0002] Luminescence down-conversion materials play an important role in solid-state lighting devices for illumination and display applications. Such materials can also be used as markers, for example in security inks.

[0003] WO2018 / 167266 discloses a composition comprising a luminescent material and a sensitizer material, wherein the luminescent material and the sensitizer material are selected so that the sensitizer material has an emission spectrum that at least partially overlaps with one or more excitation bands of the luminescent material, and wherein the luminescent material and the sensitizer material are arranged with each other to allow non-radiative energy transfer from the sensitizer material to the luminescent material. The application also describes a method for preparing the same.

[0004] Non-radiative energy transfer from a sensitizer material to a luminescent material (sometimes also referred to as fluorescence resonance energy transfer, FRET) involves the non-radiative transfer of energy from excited sensitizer ions in the sensitizer material to acceptor (or emitter) ions in the luminescent material, as evidenced by increased emission from emitter ions in the luminescent material after the sensitizer ions in the sensitizer material have been selectively excited.

[0005] Nanomaterials have attracted attention due to their high surface area and small volume, which enables the close spatial arrangement of luminescent materials to exploit inter-particle FRET.

[0006] In order to be able to effectively exploit inter-particle FRET, it is desirable to have luminescent particles of very small size (<10 nm). However, suitable nanomaterials may be of poor quality (chemical, stability, optical and / or physical) due to their small size and poor crystallinity. This can be overcome by (pre)baking or annealing the nanomaterials, but this usually results in larger or aggregated particles. Such larger or aggregated particles do not mix well, resulting in poor inter-particle FRET. When annealing pre-mixed nanomaterials, quenching may occur.

[0007] Therefore, there is still a need for luminescent nanomaterials with improved quality and stability at small sizes. In addition, there is also a need for luminescent compositions that exhibit high photoluminescent quantum yield (QY) and improved stability, and methods for preparing the same. Summary of the invention

[0008] According to the present invention, a composite luminescent particle is provided, comprising: (i) a first luminescent material, which is a rare earth, an S2-configuration ion or a phosphorescent material doped with a transition metal; (ii) a second luminescent material, which is a rare earth, an S2-configuration ion or a phosphorescent material doped with a transition metal; and (iii) an oxide material coating having a melting point of 700° C. or higher, wherein the oxide material is selected from silicon oxide, aluminum oxide, phosphate or magnesium oxide, wherein the D 50 The values ​​are ≥ 1 nm and ≤ 100 μm as measured using a transmission electron microscope (TEM).

[0009] According to the present invention, a luminescent composition is also provided, comprising: (i) a first luminescent material, which is a phosphorescent material of rare earth, S2 configuration ions or doped transition metal; (ii) a second luminescent material, which is a phosphorescent material of rare earth, S2 configuration ions or doped transition metal, wherein at least one of the first luminescent material or the second luminescent material is coated with (iii) an oxide material having a melting point of 700° C. or higher, wherein the oxide material is selected from silicon oxide, aluminum oxide, phosphate or magnesium oxide, and wherein the D of the coating material is 50 The values ​​are ≥ 1 nm and ≤ 100 μm as measured using a transmission electron microscope (TEM).

[0010] The composite luminescent particles and luminescent compositions according to the present invention exhibit good absorption / emission properties and high photoluminescence quantum yields (QY). The luminescent compositions of the present invention or luminescent compositions comprising the particles of the present invention exhibit non-radiative energy transfer (sometimes also referred to as fluorescence resonance energy transfer, FRET). The composite luminescent particles may also exhibit internal FRET.

[0011] Oxide materials with a melting point of 700°C or higher are selected from silicon oxide, aluminum oxide, phosphate or magnesium oxide, and are used for encapsulation (e.g., silicon dioxide), which can improve the optical properties of the individual particles themselves. By adjusting the shell thickness, the IFRET performance of the material and the luminescent properties of the composite luminescent particles and luminescent compositions (e.g., excitation and emission wavelengths) can also be adjusted. In addition, the oxide material can prevent ion diffusion between the luminescent materials. In a certain embodiment, the oxide material can also be doped with luminescent ions.

[0012] According to the present invention, there is also provided a method for obtaining composite luminescent particles, comprising the following steps:

[0013] a) providing (i) a first luminescent material, which is a phosphorescent material of a rare earth, an ion of S2 configuration or a doped transition metal, or a precursor of the first luminescent material; (ii) a second luminescent material, which is a phosphorescent material of a rare earth, an ion of S2 configuration or a doped transition metal, or a precursor of the second luminescent material; and also providing (iii) a precursor of an oxide material, wherein the oxide material has a melting point of at least 700° C., wherein the oxide material is selected from silicon oxide, aluminum oxide, phosphate or magnesium oxide,

[0014] b) mixing the first luminescent material or the precursor thereof, the second luminescent material or the precursor thereof and the precursor of the oxide material,

[0015] c) curing the precursor of the oxide material to obtain a cured particle, the cured particle comprising the first luminescent material or the precursor thereof, the second luminescent material or the precursor thereof and the coating of the oxide material, and

[0016] d) heating the solidified particles at a temperature of at least 200°C.

[0017] The composite luminescent particles according to the present invention can be obtained according to the method of the present invention.

[0018] A method for obtaining a luminescent composition is also provided, comprising the following steps:

[0019] a) providing (i) a first luminescent material, which is a phosphorescent material of a rare earth, an ion of S2 configuration or a doped transition metal, or a precursor of the first luminescent material; (ii) a second luminescent material, which is a phosphorescent material of a rare earth, an ion of S2 configuration or a doped transition metal, or a precursor of the second luminescent material; and also providing (iii) a precursor of an oxide material, wherein the oxide material has a melting point of at least 700° C., wherein the oxide material is selected from silicon oxide, aluminum oxide, phosphate or magnesium oxide,

[0020] b) mixing the second luminescent material or the precursor thereof with a precursor of the oxide material,

[0021] c) curing a precursor of the oxide material to obtain a cured particle, the cured particle comprising the second luminescent material or the precursor thereof and a coating of the oxide material,

[0022] d) mixing said solidified particles with said first luminescent material or said precursor thereof, wherein said first luminescent material or said precursor thereof is optionally coated with an oxide material, said oxide material having a melting point of at least 700° C., and

[0023] e) heating the mixture at a temperature of at least 200° C.,

[0024] The first luminescent material is capable of emitting light within a first wavelength range, and the second luminescent material is capable of absorbing light within a second wavelength range and has an emission spectrum that at least partially overlaps with one or more excitation bands of the first luminescent material.

[0025] The method of the present invention can obtain the luminescent composition of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Two composite luminescent particles (a, b) according to the invention and a luminescent composition according to the invention are schematically shown.

[0027] Figure 2 The mixture of LaPO4:50%Tb and Y2O3:15%Eu nanoparticles according to Comparative Example A (dotted line) and Comparative Example B (dashed line) is shown in FIG. 3+ Photoluminescence spectra under excitation (350 nm). The dotted and dashed lines indicate that the weight ratios of LaPO4:50%Tb and Y2O3:15%Eu nanoparticles in the mixture are 1:1 and 3:1, respectively.

[0028] Figure 3 Shown are the photoluminescence spectra of Y2O3:15%Eu particles (solid line) and untreated Y2O3:15%Eu nanoparticles (dotted line) according to Example 1. Excitation at 533 nm.

[0029] Figure 4 Shown is the photoluminescence spectrum of YAG:1%Ce nanoparticles according to Example 2. Excitation at 450 nm.

[0030] Figure 5 Shown are the photoluminescence spectra of particles comprising LaPO4:50% Tb and Y2O3:15% Eu nanoparticles according to Example 3 (solid line) and a mixture according to Comparative Example B. Excitation at 350 nm.

[0031] Figure 6 Shown are the photoluminescence spectra of particles comprising LaPO4:50% Tb and Y2O3:15% Eu nanoparticles according to Example 4 (solid line) and a mixture according to Comparative Example B. Excitation at 350 nm.

[0032] Figure 7 Shown are the photoluminescence spectra of particles comprising LaPO4:50% Tb and Y2O3:15% Eu nanoparticles according to Example 5 (solid line) and a mixture according to Comparative Example B. Excitation at 350 nm.

[0033] Figure 8Shown are the photoluminescence spectra of particles according to Example 6 (solid line) and particles according to Example 3 (dotted line). Excitation at 350 nm.

[0034] Fig. 9 Shown are the photoluminescence spectra of particles according to Example 7 (solid line) and Comparative Example D (dotted line). Excitation at 440 nm.

[0035] Fig.10 Shown are the photoluminescence spectra of particles according to Example 9 (solid line), Example 10 (dashed line) and Comparative Example E (dotted line). Excitation at 440 nm.

[0036] Fig.11 Shown is the photoluminescence spectrum of particles according to Example 11. Excitation at 440 nm.

[0037] Fig.12 Shown is the photoluminescence spectrum of particles according to Example 12. Excitation at 440 nm.

[0038] Fig.13 Shown is the photoluminescence spectrum of particles according to Example 13. Excitation at 440 nm. DETAILED DESCRIPTION

[0039] Composite luminescent nanoparticles

[0040] The present invention provides a composite luminescent particle, which comprises: (i) a first luminescent material, which is a rare earth, an S2-configuration ion or a phosphorescent material doped with a transition metal; (ii) a second luminescent material, which is a rare earth, an S2-configuration ion or a phosphorescent material doped with a transition metal; and (iii) a coating of an oxide material having a melting point of 700° C. or higher, wherein the oxide material is selected from silicon oxide, aluminum oxide, phosphate or magnesium oxide, wherein the D 50 The value is ≥1 nm and ≤100 μm, as measured using a transmission electron microscope (TEM). 50 The D of the composite luminescent particle is measured as the median length of the particle, measured from a collection of at least 50 representative particles. The length is defined as the maximum diameter of the particle. 50 Value, including coating.

[0041] The first luminescent material and the second luminescent material are rare earth, s2 configuration ions or phosphorescent materials doped with transition metals. In the present disclosure, rare earth, s2 configuration ions or phosphorescent materials doped with transition metals are materials that can emit light, that is, they emit light when exposed to a certain type of radiation energy, and are doped with rare earth metals, s2 configuration ions or transition metal ions. As known to the technician, rare earth-doped phosphorescent materials include host lattices doped with optically active ions. Rare earth metal ions are defined herein as ions of yttrium, scandium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium. Transition metal ions are defined herein as any ions in the d zone of the periodic table, and s2 configuration ions are defined as any ions with s2 electronic configurations. Examples of s2 configuration ions are Ge, Br, Br, Br, Br, Br, Br, Br, Br and Br. 2+ , Pb 2+ and Bi 3+ .

[0042] Preferably, the luminescent material is doped with trivalent ions of at least one of cerium, europium or terbium. These ions are capable of emitting in the visible spectrum under appropriate excitation, making them attractive for lighting.

[0043] Preferably, the luminescent material is selected from oxides, fluorides, nitrides, borates, garnets, molybdates, phosphates, vanadates, chlorides, sulfides, selenides, silicates, aluminates, oxyfluorides, oxychlorides, oxynitrides, oxysulfides, oxyselenides, fluorine chlorides, fluorosilicates and fluorobromides or combinations thereof. These materials form a lattice into which rare earth metal ions can be doped.

[0044] More preferably, the luminescent material is selected from oxides, garnets, phosphates, vanadates or combinations thereof. Even more preferably, the luminescent material is selected from Y3Al5O 12 、Lu3Al5O 12 , Y2O3, YVPO4, YVO4 or LaPO4 or a combination thereof. It has been found that these luminescent materials exhibit desirable optical properties.

[0045] Preferably, the first luminescent material is an oxide, and the second luminescent material is also an oxide.

[0046] Preferably, the first luminescent material is (Lu,Y)3Al5O 12 :Eu 3+ 、Y2O3:Eu 3+ , can be optionally further doped with Tb 3 + These materials are stable and exhibit strong europium emission.

[0047] Preferably, the second luminescent material is Y3Al5O 12 :Ce 3+、Lu3Al5O 12 :Ce 3+ , can be optionally further doped with Tb 3 + These materials are stable, exhibit strong cerium emission and can be excited by blue light.

[0048] In another preferred embodiment, one of the luminescent materials is a phosphate and the other luminescent material is an oxide. More preferably, the first luminescent material is Y2O3:Eu 3+ , and the second luminescent material is LaPO4:Tb 3+ .

[0049] The composite luminescent particle further comprises a coating of an oxide material having a melting point of 700° C. or higher. The oxide material forms a coating around the first luminescent material and the second luminescent material. This protects the luminescent materials from damage from, for example, moisture or heat.

[0050] The oxide material has a melting point of 700°C or higher. Preferably, the melting point is 900°C or higher, more preferably 1200°C or higher. The high melting point allows the composite luminescent particles to be processed, for example by annealing the luminescent material, without melting or agglomerating the composite luminescent particles. Therefore, the melting point of the oxide material is preferably higher than the lowest melting point of the luminescent material.

[0051] The oxide material is selected from silicon oxide, aluminum oxide or phosphate. More preferably, the oxide material is selected from silicon dioxide, aluminum oxide, magnesium oxide and phosphate. These materials are physically, chemically and thermally stable. Preferably, the second material is silicon dioxide because the material shows good stability. Silicon dioxide can also be easily dispersed in water and other hydrophilic solvents, so that the composite luminescent particles are suitable for various applications. In a certain embodiment, the oxide material can be doped with luminescent ions.

[0052] Preferably, the first luminescent material is capable of emitting light in a first wavelength range, and the second luminescent material is capable of absorbing light in a second wavelength range and has an emission spectrum that at least partially overlaps one or more excitation bands of the first luminescent material. Such a composite luminescent particle may exhibit FRET between the two materials.

[0053] More preferably, the first luminescent material and the second luminescent material are arranged with respect to each other to allow non-radiative energy transfer from the second luminescent material to the first luminescent material.

[0054] Preferably, the first luminescent material and the second luminescent material form separate domains within the oxide material, wherein the domains have a size, and the smallest size D of the domains is 50The value is ≥0.5 nm and ≤100 nm, more preferably ≥0.5 nm and ≤50 nm, most preferably ≥0.5 nm and ≤10 nm, as measured using a transmission electron microscope (TEM). Preferably, the D 50 The value is ≥0.5nm and ≤100nm, more preferably ≥0.5nm and ≤50nm, and most preferably ≥0.5nm and ≤10nm. Therefore, the domain size does not include a coating of oxide material. Domains of this size are suitable for FRET. Such small domains are ideal because they have a high surface area. The oxide material forms a stable matrix around the domain, thereby preventing ion exchange or quenching. In addition, the oxide material keeps the domain in place so that the distance between the domains remains unchanged regardless of post-treatment.

[0055] Preferably, D of the composite luminescent particle 50 The value is ≥1 nm and ≤50 μm, as measured using a transmission electron microscope. More preferably, the D 50 The value is ≥20nm and ≤10μm, most preferably ≥50nm and ≤10μm, as measured using a transmission electron microscope (TEM). Smaller particle sizes of the first luminescent material and the second luminescent material allow for inter-particle FRET, and due to the thinner oxide material coating, the distance between the luminescent materials is also smaller. Smaller particles also have a larger surface area, which may be desirable.

[0056] Luminescent composition

[0057] Also provided is a luminescent composition, comprising (i) a first luminescent material, which is a rare earth, an S2-configuration ion, or a phosphorescent material doped with a transition metal, (ii) a second luminescent material, which is a rare earth, an S2-configuration ion, or a phosphorescent material doped with a transition metal,

[0058] wherein at least one of the first luminescent material or the second luminescent material is coated with (iii) an oxide material having a melting point of 700° C. or higher, wherein the oxide material is selected from silicon oxide, aluminum oxide, phosphate or magnesium oxide, and wherein the D 50 The values ​​are ≥ 1 nm and ≤ 100 μm as measured using a transmission electron microscope (TEM).

[0059] Preferably, the first luminescent material is capable of emitting light in a first wavelength range and the second luminescent material is capable of absorbing light in a second wavelength range and has an emission spectrum at least partially overlapping with one or more excitation bands of the first luminescent material.

[0060] More preferably, the first luminescent material and the second luminescent material are arranged with respect to each other to allow non-radiative energy transfer from the second luminescent material to the first luminescent material.

[0061] In one embodiment, the luminescent composition includes a first luminescent material as particles coated with an oxide material and a second luminescent material as particles coated with an oxide material. Since the oxide material coats the first luminescent material and the second luminescent material, the luminescent particles can be better mixed and the luminescent composition is more uniform. Such a composition as Figure 1 'c'.

[0062] In one embodiment, only one of the first luminescent material or the second luminescent material is contained in the particles coated with the oxide material. In this case, preferably, the smallest size D of the other luminescent material is 50 The value is preferably ≥0.5 nm and ≤100 nm, more preferably ≥0.5 nm and ≤50 nm, most preferably ≥0.5 nm and ≤10 nm, as measured using a transmission electron microscope (TEM). Preferably, D of the other luminescent material is 50 The value is ≥0.5nm and ≤100nm, more preferably ≥0.5nm and ≤50nm, and most preferably ≥0.5nm and ≤10nm. In another embodiment, another luminescent material is provided as a bulk material, and the coating particles are provided on the bulk luminescent material. In this context, the term "bulk" particularly means and / or includes larger than nanometer scale, for example, a diameter greater than 100nm and including micrometer scale.

[0063] first luminescent material and second luminescent material

[0064] Preferably, the first luminescent material is capable of emitting light in a first wavelength range, and the second luminescent material is capable of absorbing light in a second wavelength range and has an emission spectrum that at least partially overlaps one or more excitation bands of the first luminescent material. For all embodiments in this case, the following applies.

[0065] The first luminescent material may be capable of emitting light within a first wavelength range. The skilled person will appreciate that the first luminescent material is used as a luminescent material in a luminescent composition according to the present invention. The first wavelength range may be any wavelength range of interest. Preferred wavelength ranges will be described below.

[0066] The second luminescent material may be capable of absorbing light within a second wavelength range. The skilled person will appreciate that the second luminescent material is used as a sensitizer material in the luminescent composition according to the present invention. The second wavelength range may be any wavelength range of interest. Preferred wavelength ranges will be described below.

[0067] When excited by light in the second wavelength range, the second luminescent material has an emission spectrum that at least partially overlaps with one or more excitation bands of the first luminescent material. The skilled person is able to determine the overlap of the spectra based on spectra known in the art or by routine experimental determination of the spectra, such as the spectra disclosed in WO2020 / 053429.

[0068] Preferably, the emission spectrum of the second material overlaps with one or more excitation bands of the first material in the blue (440 to 480 nm), green (510 to 560 nm) or yellow (560 to 580 nm) wavelength range.

[0069] Preferably, the first luminescent material and the second luminescent material are arranged with respect to each other to allow non-radiative energy transfer (sometimes also referred to as fluorescence resonance energy transfer, FRET) from the second luminescent material (sensitizer material) to the first luminescent material (emitter material). Typically, this involves close proximity between the first and second luminescent materials, for example a distance of about 0.5 nm to about 20 nm. The skilled person is well aware of how non-radiative energy transfer can be achieved. This is described, for example, in WO2018 / 167266, the contents of which are incorporated herein by reference. The skilled person will understand that non-radiative energy transfer involves the non-radiative transfer of energy from an excited sensitizer material to an acceptor (or emitter) ion in the luminescent material. This is demonstrated by the increased selective excitation of the sensitizer material leading to an increase in emission from the emitter ions in the luminescent material. The non-radiative energy transfer of interest may arise from The skilled person will appreciate that since resonance energy transfer is inversely proportional to the sixth power of the distance between the ions (in Type energy transfer), or exponentially proportional to the distance (in the case of Dexter type energy transfer), so the arrangement that allows non-radiative energy transfer can be influenced by appropriate design of the effective distance between the sensitizer material and the emitter ion in the luminescent material.

[0070] The skilled artisan will appreciate that the first and second materials must be in close proximity for FRET to occur.

[0071] First luminescent material

[0072] The first luminescent material is capable of emitting light in a first wavelength range. The first wavelength range may be any wavelength range of interest.

[0073] Preferably, the first luminescent material comprises a red or green luminescent material. The term red luminescent material used herein refers to a material having one or more emission bands between 600nm and 700nm under appropriate excitation, and the term green luminescent material refers to a material having one or more emission bands between 510nm and 560nm under appropriate excitation. Providing a red or green luminescent material may be ideal for color development purposes. According to an alternative aspect of the present invention, the first luminescent material is a material having one or more emission bands under appropriate excitation, and the emission bands are between 700 and 1400nm (IR-A), between 580 and 600nm (amber and / or orange), between 560 and 580nm (yellow), between 480 and 510nm (cyan), between 440 and 480nm (blue), between 400-440nm (violet), between 315-400nm (UV-A) and / or between 280-315nm (UV-B).

[0074] The first luminescent material includes a rare earth, an s2 configuration ion, or a phosphorescent material doped with a transition metal. The phosphorescent material may be a phosphor doped with a divalent or trivalent rare earth. Examples of suitable rare earth doped phosphorescent 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+ ) and combinations thereof, examples of suitable transition metal-doped phosphors are BaMgAl 14 O 23 :Mn 2+ 、Mg(Al,Ga)2O4:Mn 2+ 、Zn2SiO4:Mn 2+ 、K2SiF6:Mn 4+ 、MgF2.GeO2:Mn 4+ and combinations thereof.

[0075] Phosphorescent materials are currently available on the open market or can be synthesized, for example as described in [Riwotzki, K.; Meyssamy, H.; Kornowski, A.; Haase, MJ Phys. Chem. B. 2000, 104, 2824-2828].

[0076] As known to the skilled person, rare earth, s2 configuration ion or transition metal doped phosphorescent materials include a host lattice doped with optically active ions.

[0077] Preferably, the preferred host lattice of the first luminescent material is doped with a 3+ , Tb 3+ , Mn 2+ and Mn 4+ These ions provide good emission characteristics, such as emission bands that are strong and / or located in the red or green part of the visible spectrum.

[0078] In the case of Eu doping 3+ In the case of Tb doped, the first luminescent material may, for example, have a host lattice doping rate of at least about 1%, more preferably between about 5% and about 80%. 3+ In the case of the first luminescent material, the host lattice may have a doping ratio of at least about 10%, more preferably between about 30% and about 80% Tb. 3+ . In the case of Mn doping 4+ In the case of Mn doping, the first luminescent material may, for example, have a host lattice doping rate of about 0.1-30%, most preferably between about 1-10%. 2+ In the case of , the first luminescent material may, for example, have a host lattice doping ratio of about 0.1-30%, most preferably between about 1-10%.

[0079] In one exemplary embodiment, the first luminescent material is selected from (Ca, Sr)Ga2O6:Eu 3+ (or Tb 3+ ), (Ca,Sr,Ba)La2Bi2(SiO4)3O:Eu 3+ (or Tb 3+ )、(Ca,Sr,Ba)SnO3:Eu 3+ (and / or Tb 3+ )、(Ca,Y,Gd)MoO4:Eu 3 + (or Tb 3+ )、(Y,Gd)BO3(pseudo-vaterite):Eu 3+ (or Tb 3+ )、(Y,Tb)SiO5:Eu 3+ (or Tb3+ )、A-La2O3:Eu 3+ (or Tb 3+ )、Ba2(SiO4):O 2- :Eu 3+ (or Tb 3+ )、Ba2MgSi2O7:Eu 3+ (or Tb 3+ )、Ba2Y(BO3)2Cl:Eu 3+ (or Tb 3+ )、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+ ), 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 :Eu3+ (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 Tb 3+ )、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+ )、Cs3Ge3O9:Eu 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 Tb3+ )、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 + ), GdA l3 (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):Eu3+ (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 Tb3+ )、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+ )、Lu3Al5O 12 :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:Eu 3+ (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:Eu3+ (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+ or a mixture thereof.

[0080] The skilled person will understand that the symbol: Eu 3+ (or: Tb 3+ Or: Ce 3+ Or: Mn 2+ Or: Mn 4+ ) indicates that the host lattice is doped with Eu 3 + (or doped with Tb 3+ 、Ce 3+ , Mn 2+ or Mn 4+ ).

[0081] Second luminescent material

[0082] Any suitable inorganic luminescent material can be used as the second luminescent material. The second material is capable of absorbing light in a second wavelength range. The second wavelength can be any wavelength range of interest.

[0083] Preferably, the second luminescent material has one or more excitation bands in the wavelength range between 300 and 580 nm, preferably, wherein the second luminescent material has one or more excitation bands in the UV-A (315 to 400 nm), violet (400 to 440 nm), blue (440 to 490 nm) or green (510 to 560 nm) wavelength range, most preferably in the blue (440 to 490 nm) wavelength range. (Al, In, Ga) N based LEDs provide efficient "pump" light generation in the violet to blue wavelength range (about 400 nm to about 490 nm). Examples of blue excitable materials are CaAlSiN3:Eu 2+ and Y3Al5O 12 :Ce 3+ .

[0084] In other aspects of the invention, the second luminescent material is a material having one or more excitation bands between 700 and 1400 nm (IR-A), between 580 and 600 nm (amber and / or orange), between 560 and 580 nm (yellow), between 510-560 nm (green), between 480 and 510 nm (cyan), between 440 and 480 nm (blue), between 400-440 nm (violet), between 315-400 nm (UV-A) and / or between 280-315 nm (UV-B).

[0085] In another preferred embodiment, the host lattice of the second luminescent material is garnet, fluoride, silicate, phosphate or nitride, more preferably selected from Y3Al5O 12 ("YAG"), Lu3Al5O 12 ("LuAG"), LaPO4, MgF2, CaF2, Sr2SiO4, Ba2SiO4, Ca2MgSi2O7, LiSrPO4, CaAlSiN3 or a combination thereof. Preferably, the preferred host lattice of the second luminescent material is doped with one or more selected from Eu 2+ , Pb 2+ 、Bi 3+ and Ce 3+ ions, more preferably Eu 2+ or Ce 3+ With Tb 3+ The most preferred combination is Ce 3+ With Tb 3+ combination.

[0086] Preferably, the host lattice of the second luminescent material or its precursor is garnet, such as Y3Al5O 12 ("YAG") or Lu3Al5O12 ("LuAG") or a combination thereof. Most preferably, the host lattice is selected from Y3Al5O 12 ("YAG") or Lu3Al5O 12 ("LuAG") or a combination thereof, and the dopant includes Ce 3+ , optionally with Tb 3+ combination.

[0087] Preferably, when doping Ce 3+ In the case of, the second luminescent material has a host lattice doping level of about 0.05-5%, more preferably about 0.1-4%.

[0088] Method for obtaining composite luminescent particles

[0089] A method for obtaining composite luminescent particles is also provided. The method comprises the following steps:

[0090] a) providing (i) a first luminescent material, which is a phosphorescent material of a rare earth, an ion of S2 configuration or a doped transition metal, or a precursor of the first luminescent material; (ii) a second luminescent material, which is a phosphorescent material of a rare earth, an ion of S2 configuration or a doped transition metal, or a precursor of the second luminescent material; and also providing (iii) a precursor of an oxide material, wherein the oxide material has a melting point of at least 700° C., wherein the oxide material is selected from silicon oxide, aluminum oxide, phosphate or magnesium oxide,

[0091] b) mixing the first luminescent material or the precursor thereof, the second luminescent material or the precursor thereof and the precursor of the oxide material,

[0092] c) curing the precursor of the oxide material to obtain a cured particle, the cured particle comprising the first luminescent material or the precursor thereof, the second luminescent material or the precursor thereof and the coating of the oxide material, and

[0093] d) heating the solidified particles at a temperature of at least 200°C.

[0094] This process allows obtaining the composite luminescent particles of the invention.

[0095] Step a) includes providing (i) a first luminescent material, which is a phosphorescent material of a rare earth, an S2 configuration ion or a doped transition metal, or a precursor of the first luminescent material; (ii) a second luminescent material, which is a phosphorescent material of a rare earth, an S2 configuration ion or a doped transition metal, or a precursor of the second luminescent material; and also providing (iii) a precursor of an oxide material, wherein the oxide material has a melting point of at least 700°C, wherein the oxide material is selected from silicon oxide, aluminum oxide, phosphate or magnesium oxide.

[0096] The luminescent material is a phosphorescent material of rare earth, S2 configuration ions or doped transition metals as defined above.

[0097] Preferably, the luminescent material or said precursor thereof is provided in the form of particles, wherein the smallest dimension D of said particles is 50 The values ​​are ≥ 0.5 nm and ≤ 100 nm. This allows obtaining domains within the matrix of oxide material.

[0098] Preferably, the smallest dimension D of said particles of the luminescent material or said precursor thereof is 50 Preferably, the D of said particles of the luminescent material or said precursor thereof is ≥0.5 nm and ≤50 nm, more preferably ≥0.5 nm and ≤10 nm, as measured using a transmission electron microscope (TEM). 50 The value is ≥ 0.5 nm and ≤ 50 nm, more preferably ≥ 0.5 nm and ≤ 10 nm. Smaller particles allow smaller domains to be obtained within the composite luminescent particle, which allows better FRET to be achieved.

[0099] Preferably, at least one of the first luminescent material or the second luminescent material is A3B5O 12 :RE garnet nanoparticles, wherein A is one or more of yttrium, lutetium and gadolinium, B is one or more of aluminum, gallium and scandium, and RE is a rare earth metal, and the garnet nanoparticles can be prepared according to a method known in the art, the method being selected from:

[0100] a. Sugar thermal method, more preferably as described in Odziomek et al. J. Mater. Chem. C 2017, 5, 12561,

[0101] b. precipitation method, more preferably as described in EP21215315, which is incorporated herein by reference,

[0102] c. a two-step precipitation method, more preferably as described in EP21218015, which is incorporated herein by reference, or

[0103] d. Any other method, such as those described in Berends et al. Chem. Rev. 2020, 120, 24, 13461-13479 or elsewhere in the art.

[0104] Step b) comprises mixing the first luminescent material or the precursor thereof, the second luminescent material or the precursor thereof and the precursor of the oxide material.

[0105] The oxide material is preferably as defined above.

[0106] Preferably, the oxide precursor is selected from the group consisting of organic silicates, silicon salts, aluminum salts, magnesium salts and phosphates.

[0107] More preferably, the oxide precursor is selected from silicon salts, aluminum salts, magnesium salts and phosphate salts, and the salt is selected from nitride salts or chloride salts. More preferably, the precursor is an orthosilicate.

[0108] In one embodiment, the mixing in step b) is performed by simply adding the precursor of the oxide material to a dispersion of the luminescent material or its precursor. Preferably, the dispersion medium is a water / ethanol mixture. Preferably, the method is performed according to reaction.

[0109] In another embodiment, the mixing is performed by first preparing a water-in-oil microemulsion in which the luminescent material is located in the core of the droplets, and then adding TEOS to the microemulsion. An example of this method is described in Koole, R.; van Schooneveld, MM; Hilhorst, J.; de Mello Donegá, C.; 't Hart, DC; van Blaaderen, A.; Vanmaekelbergh, D.; Meijerink, A. Chem. Mater. 2008, 20, 2503-2512.

[0110] Preferably, step b) comprises stirring. This allows the luminescent material to remain in the dispersion and the precursor of the oxide material to be evenly distributed.

[0111] Preferably, the mixture is further stirred after step b) but before step c), for example by ultrasound treatment. This further ensures a uniform distribution of the precursor of the oxide material and a good dispersion of the luminescent material.

[0112] By varying method steps b) and c), the distance between the domains of the luminescent material within the oxide material can be adjusted. This can be adjusted depending on the material. Accurately adjusting the inter-particle separation between the first luminescent material and the second luminescent material in the final composite luminescent particle can control the energy transfer efficiency, thereby well controlling the final luminescent spectrum color.

[0113] Figure 1 Showing how the distance can be adjusted in various ways: Embodiment "a" shows a composite light-emitting particle where the domains of light-emitting material are almost touching. Embodiment "b" shows a larger distance between the domains, but still within the same composite light-emitting particle. Embodiment "c" shows two particles where each particle contains one light-emitting material, which allows for an even larger distance.

[0114] In one embodiment, method step b) is performed in a single step, thereby forming a single mixture. This results in a minimum distance between the domains. Adjusting the distance between the different domains is crucial because it allows control of the appropriate energy transfer (closer distances produce higher energy transfer efficiency) and also control of quenching effects (e.g. charge transfer quenching, where there is less quenching for greater distances).

[0115] In one embodiment, method step b) comprises:

[0116] - mixing the first luminescent material or the precursor thereof with a precursor of the oxide material in a first container, and mixing the second luminescent material or the precursor thereof with a precursor of the oxide material in a second container, and

[0117] - Mixing the mixture.

[0118] Mixing the luminescent material separately from the precursor of the oxide material allows adjusting the distance between the luminescent materials in the final particle. Thus, this embodiment provides an intermediate distance between domains.

[0119] In one embodiment, method step b) comprises:

[0120] b1) mixing the first luminescent material or the precursor thereof with a precursor of the oxide material in a first container, and mixing the second luminescent material or the precursor thereof with a precursor of the oxide material in a second container,

[0121] b2) at least partially curing at least one of the obtained mixtures,

[0122] b3) mixing the at least partially cured mixture.

[0123] This leads to even larger distances between domains.

[0124] Step c) comprises curing said precursor of said oxide material to obtain cured particles, said cured particles comprising said first luminescent material or said precursor thereof, said second luminescent material or said precursor thereof and a coating of said oxide material.

[0125] This curing can be carried out, for example, by condensation or hydrolysis reaction. Preferably, the curing is a hydrolysis reaction. More preferably, the curing is carried out by adding an ammonia solution.

[0126] Preferably, the curing is carried out in a slow manner and / or during stirring. This prevents the particles from agglomerating together. For example, the ammonia solution can be added dropwise with continuous stirring.

[0127] Preferably, the method further comprises drying the solidified particles. More preferably, the method comprises drying the solidified particles at a temperature of 80°C to 125°C.

[0128] Preferably, the method further comprises drying the solidified particles at 80°C to 125°C, and grinding the dried particles after the solidification step c) and / or grinding the particles after the heating step d).

[0129] Step d) comprises heating the solidified particles at a temperature of at least 200° C. This can remove crystal defects in the luminescent material. In the case of a luminescent material precursor, this step can form the luminescent material.

[0130] The oxide material coating provides a protective barrier to prevent ion diffusion between the light-emitting materials during the high temperature annealing step and passivates surface defects on the domains of the light-emitting materials. Both effects lead to higher luminescence intensity.

[0131] Preferably, the heating is at least partially carried out in a reducing environment. A reducing environment is an environment that prevents oxidation. Preferably, the reducing environment comprises carbon monoxide. Reducing environment conditions can be obtained by using carbon powder in a double crucible setup, wherein a crucible containing solidified particles is placed inside a larger crucible containing carbon powder and covered with a lid.

[0132] Preferably, said heating of said solidified particles comprises heating at a temperature of at least 500°C, preferably at least 600°C, and preferably at a temperature below 2000°C, more preferably at a temperature below 1500°C.

[0133] Preferably, heating the solidified particles comprises heating at a temperature below the melting temperature of the oxide coating.

[0134] When the first luminescent material and the second luminescent material are Y2O3, Y3Al5O 12 , and / or Lu3Al5O 12 When the heating temperature is preferably at least 900° C. For this material, the solidified particles are preferably heated for at least 2 hours, more preferably 6 hours.

[0135] When the first luminescent material and / or the second luminescent material comprises a phosphate material such as LaPO4, the heating temperature is preferably at most 800°C. Higher temperatures may result in degradation of the phosphate material. For such materials, the solidified particles are preferably heated for at least 1 minute, preferably for several hours.

[0136] The present invention also relates to a method for obtaining a luminescent composition, comprising the following steps:

[0137] a) providing a first luminescent material, which is a phosphorescent material of rare earth, S2 configuration ion or doped transition metal, or a precursor of the first luminescent material; a second luminescent material, which is a phosphorescent material of rare earth, S2 configuration ion or doped transition metal, or a precursor of the second luminescent material; and further providing a precursor of an oxide material, wherein the oxide material has a melting point of at least 700° C., wherein the oxide material is selected from silicon oxide, aluminum oxide, phosphate or magnesium oxide,

[0138] b) mixing one of the first luminescent material or its precursor and the second luminescent material or its precursor with a precursor of the oxide material,

[0139] c) curing the precursor of the oxide material to obtain a cured particle, the cured particle comprising one of the first luminescent material or a precursor thereof and the second luminescent material or a precursor thereof and a coating of the oxide material,

[0140] d) mixing said solidified particles with another luminescent material or said precursor thereof, wherein said another luminescent material or said precursor thereof is optionally coated with an oxide material having a melting point of at least 700° C., and

[0141] e) heating the mixture at a temperature of at least 200° C.,

[0142] The first luminescent material is capable of emitting light within a first wavelength range, and the second luminescent material is capable of absorbing light within a second wavelength range and has an emission spectrum that at least partially overlaps with one or more excitation bands of the first luminescent material.

[0143] This process allows obtaining the luminescent composition of the invention.

[0144] This method differs from the method of obtaining a composite luminescent particle in that the first luminescent material and the second luminescent material are not contained in a single composite luminescent particle.

[0145] Step a) of the process of the invention is identical and therefore the same preferred embodiments apply as described above.

[0146] Step b) comprises mixing one of the first luminescent material or the precursor thereof and the second luminescent material or the precursor thereof with a precursor of the oxide material.

[0147] The oxide material is preferably as defined above, and the precursor is as defined above.

[0148] In one embodiment, the mixing of step b) is performed by simply adding the precursor of the oxide material to a dispersion of the second luminescent material or its precursor. Preferably, the dispersion medium is a water / ethanol mixture. Preferably, the method is according to reaction.

[0149] In another embodiment, the mixing is performed by first preparing a water-in-oil microemulsion in which the second luminescent material is located in the core of the droplets, and then adding TEOS to the microemulsion. An example of this method is described in Koole, R.; van Schooneveld, MM; Hilhorst, J.; de Mello Donegá, C.; 't Hart, DC; van Blaaderen, A.; Vanmaekelbergh, D.; Meijerink, A. Chem. Mater. 2008, 20, 2503-2512.

[0150] Preferably, step b) comprises stirring. This allows the luminescent material to remain in the dispersion and the precursor of the oxide material to be evenly distributed.

[0151] Preferably, the mixture is further stirred after step b) but before step c), for example by ultrasound treatment. This further ensures a uniform distribution of the precursor of the oxide material and a good dispersion of the luminescent material.

[0152] Step c) comprises curing the precursor of the oxide material. Preferably, the curing is a hydrolysis reaction. More preferably, the curing is performed by adding an ammonia solution.

[0153] Preferably, the curing is carried out in a slow manner and / or during stirring. This prevents the particles from agglomerating together. For example, the ammonia solution can be added dropwise with constant stirring.

[0154] Preferably, the method further comprises drying the solidified particles. More preferably, the method comprises drying the solidified particles at a temperature of 80°C to 125°C.

[0155] Preferably, the method further comprises drying the solidified particles at 80-125° C. and grinding the dried particles after the solidification step c) and / or grinding the particles after the heating step e).

[0156] The mixing step d) can be performed by any method known in the art, for example by dry mixing, or dispersion in a liquid followed by drying.

[0157] Heating step e) is preferably performed as described above for heating step d).

[0158] Preferably, heating the mixture comprises mixing the mixture with a salt prior to heating, as described in WO2021043762. This may protect the first luminescent material, which may be uncoated.

[0159] In one embodiment, the further luminescent material or the precursor thereof is coated with an oxide material having a melting point of at least 700° C. Preferably, the oxide material is as defined above. This can be obtained Figure 1 Implementation of 'c'.

[0160] The separation of luminescent particles or domains can be further tuned by varying the ratio between the amount of luminescent particles or their precursors and the amount of oxide coating material precursors.

[0161] The present invention also relates to a light-emitting device, comprising the composite light-emitting particle of the present invention or the light-emitting composition of the present invention. Preferably, the light-emitting device further comprises an excitation source for the light-emitting material, for example, for a second light-emitting material. Preferably, the excitation source is a UV-A, violet or blue light-emitting material, which emits light of a wavelength of 315-400nm (UV-A), 400-440nm (violet) or 440-480nm (blue), more preferably between 430-465nm, to the light-emitting material.

[0162] The light emitting device can be composed of a blue emitting LED, wherein the luminescent nanoparticles or luminescent composition according to the present invention are deposited on top of the LED chip. The nanoparticles according to the present invention can be incorporated into a polymer or silicone paste deposited on the blue LED chip and then cured.

[0163] The invention also relates to a lighting system comprising the light emitting device according to the invention. Preferably, the lighting system is selected from lamps or luminaires, office lighting systems, home application systems, shop lighting systems, home lighting systems, accent lighting systems, spotlight lighting systems, theatre lighting systems, fibre optic application systems, projection systems, self-luminous display systems, pixelated display systems, segmented display systems, warning sign systems, medical lighting application systems, indicator sign systems and decorative lighting systems, portable systems, automotive applications and greenhouse lighting systems.

[0164] The present invention also relates to the use of a luminescent composition according to the present invention or a luminescent material comprising the luminescent nanoparticles of the present invention as a marker. A marker is a marker added to a material to allow various forms of testing. Compared to conventional methods, the overall excitation / emission spectrum of the composite luminescent particles and / or luminescent composition according to the present invention may have unique characteristics, so that they can be used as markers in anti-counterfeiting applications. For example, US7667828B discloses a marking system comprising a variety of markers that are different from each other.

[0165] The present invention is further defined in the following terms:

[0166] 1. A composite luminescent particle, comprising (i) a first luminescent material, which is a rare earth, an S2 configuration ion or a phosphorescent material doped with a transition metal, (ii) a second luminescent material, which is a rare earth, an S2 configuration ion or a phosphorescent material doped with a transition metal, and further comprising (iii) a coating of an oxide material having a melting point of 700° C. or higher, wherein the oxide material is selected from silicon oxide, aluminum oxide, phosphate or magnesium oxide,

[0167] Wherein, the D of the composite luminescent particle 50 The values ​​are ≥ 1 nm and ≤ 100 μm as measured using a transmission electron microscope (TEM).

[0168] 2. A composite luminescent particle according to clause 1, wherein the first luminescent material is capable of emitting light in a first wavelength range, and the second luminescent 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 luminescent material,

[0169] Preferably, wherein the first luminescent material and the second luminescent material are arranged with respect to each other to allow non-radiative energy transfer from the second luminescent material to the first luminescent material.

[0170] 3. A composite luminescent particle according to clause 2, wherein the first luminescent material and the second luminescent material form separate domains within the oxide material, wherein the domains have a size, and the smallest size of the domains is D 50 The value is ≥ 0.5 nm and ≤ 100 nm, more preferably ≥ 0.5 nm and ≤ 50 nm, most preferably ≥ 0.5 nm and ≤ 10 nm, as measured using a transmission electron microscope (TEM).

[0171] 4. A composite luminescent particle according to any one of the preceding clauses, wherein D of the composite luminescent particle 50 The value is ≥1 nm and ≤50 μm, more preferably ≥20 nm and ≤10 μm, most preferably ≥50 nm and ≤10 μm, as measured using a transmission electron microscope (TEM).

[0172] 5. A luminescent composition comprising (i) a first luminescent material, which is a phosphorescent material doped with a rare earth or transition metal ion having an S2 configuration, (ii) a second luminescent material, which is a phosphorescent material doped with a rare earth or transition metal ion having an S2 configuration,

[0173] wherein at least one of the first luminescent material or the second luminescent material is contained in a particle, the particle is coated with (iii) an oxide material having a melting point of 700° C. or higher, wherein the oxide material is selected from silicon oxide, aluminum oxide, phosphate or magnesium oxide, and wherein the D 50The value is ≥1 nm and ≤100 μm, as measured using a transmission electron microscope (TEM),

[0174] Preferably, wherein the first luminescent material is capable of emitting light in a first wavelength range, and the second luminescent 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 luminescent material,

[0175] More preferably, wherein the first luminescent material and the second luminescent material are arranged with respect to each other to allow non-radiative energy transfer from the second luminescent material to the first luminescent material.

[0176] 6. A composite luminescent particle according to any one of clauses 1 to 4, or a luminescent composition according to clause 5, wherein the first luminescent material and / or the second luminescent material is selected from 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,

[0177] Preferably selected from oxides, phosphates, vanadates or combinations thereof,

[0178] More preferably, Y3Al5O 12 、Lu3Al5O 12 , Y2O3, YVPO4, YVO4 or LaPO4 or a combination thereof.

[0179] 7. A composite luminescent particle according to any one of clauses 1 to 4 or 6, or a luminescent composition according to clause 5 or 6, wherein the oxide material is selected from silicon dioxide, aluminum oxide, magnesium oxide and phosphate.

[0180] 8. A method for obtaining composite luminescent particles, comprising the following steps:

[0181] a) providing (i) a first luminescent material, which is a phosphorescent material of a rare earth, an ion of S2 configuration or a doped transition metal, or a precursor of the first luminescent material; (ii) a second luminescent material, which is a phosphorescent material of a rare earth, an ion of S2 configuration or a doped transition metal, or a precursor of the second luminescent material; and also providing (iii) a precursor of an oxide material, wherein the oxide material has a melting point of at least 700° C., wherein the oxide material is selected from silicon oxide, aluminum oxide, phosphate or magnesium oxide,

[0182] b) mixing the first luminescent material or the precursor thereof, the second luminescent material or the precursor thereof and the precursor of the oxide material,

[0183] c) curing the precursor of the oxide material to obtain a cured particle, the cured particle comprising the first luminescent material or the precursor thereof, the second luminescent material or the precursor thereof and a coating of the oxide material, and

[0184] d) heating the solidified particles at a temperature of at least 200°C.

[0185] 9. The method according to clause 8, wherein the first luminescent material is capable of emitting light in a first wavelength range, and the second luminescent 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 luminescent material.

[0186] 10. The process according to clause 8 or 9, wherein process step b) is carried out in a single step, thereby forming a single mixture.

[0187] 11. The method according to clause 8 or 9, wherein method step b) comprises:

[0188] b1) mixing the first luminescent material or the precursor thereof with a precursor of the oxide material in a first container, and mixing the second luminescent material or the precursor thereof with a precursor of the oxide material in a second container,

[0189] b2) optionally, at least partially curing at least one of the obtained mixtures,

[0190] b3) mixing the optionally at least partially cured mixture.

[0191] 12. A method for obtaining a luminescent composition, comprising the following steps:

[0192] a) providing (i) a first luminescent material, which is a phosphorescent material of a rare earth, an ion of S2 configuration or a doped transition metal, or a precursor of the first luminescent material; (ii) a second luminescent material, which is a phosphorescent material of a rare earth, an ion of S2 configuration or a doped transition metal, or a precursor of the second luminescent material; and also providing (iii) a precursor of an oxide material, wherein the oxide material has a melting point of at least 700° C., wherein the oxide material is selected from silicon oxide, aluminum oxide, phosphate or magnesium oxide,

[0193] b) mixing one of the first luminescent material or the precursor thereof and the second luminescent material or the precursor thereof with a precursor of the oxide material,

[0194] c) curing the precursor of the oxide material to obtain a cured particle, the cured particle comprising one of the first luminescent material or the precursor thereof and the second luminescent material or the precursor thereof, and a coating of the oxide material,

[0195] d) mixing said solidified particles with another luminescent material or said precursor thereof, wherein said another luminescent material or said precursor thereof is optionally coated with an oxide material, said oxide material having a melting point of at least 700° C., and

[0196] e) heating the mixture at a temperature of at least 200° C.,

[0197] The first luminescent material is capable of emitting light within a first wavelength range, and the second luminescent material is capable of absorbing light within a second wavelength range and has an emission spectrum that at least partially overlaps with one or more excitation bands of the first luminescent material.

[0198] 13. A method according to any one of clauses 8 to 12, wherein the first luminescent material or the precursor thereof and / or the second luminescent material or the precursor thereof is provided in the form of particles, and the smallest dimension D of the particles is 50 The value is ≥ 0.5 nm and ≤ 50 nm, preferably ≥ 0.5 nm and ≤ 10 nm, as measured using a transmission electron microscope (TEM).

[0199] 14. A method according to any one of clauses 8 to 13, wherein the precursor of the oxide material is selected from organosilicates, silicon salts, aluminum salts, phosphates and magnesium salts, preferably wherein the salt is selected from nitride salts or chloride salts, and / or the precursor is an orthosilicate.

[0200] 15. A method according to any one of clauses 8 to 14, wherein step c) comprises a hydrolysis reaction, preferably wherein the oxide material is silicon dioxide, and step c) comprises adding ammonia to cure a precursor of the oxide material.

[0201] 16. The method according to any one of clauses 8 to 15, further comprising drying and grinding the particles after curing step c), and / or grinding the particles after heating step d) or heating step e).

[0202] 17. A method according to any one of clauses 8 to 16, wherein the heating comprises heating at a temperature of at least 500°C, preferably at least 600°C, and preferably less than 2000°C, more preferably less than 1500°C.

[0203] 18. The method according to any one of clauses 8 to 17, wherein the heating comprises heating for at least one minute, preferably at least 5 minutes.

[0204] 19. The method according to any one of clauses 8 to 18, wherein the heating is at least partially carried out under a reducing environment.

[0205] 20. A light emitting device comprising the composite light emitting particle according to any one of clauses 1 to 6 or the light emitting composition according to clause 7, and a violet and / or blue light emitting semiconductor material.

[0206] 21. A system comprising the composite luminescent particle according to any one of clauses 1 to 6, the luminescent composition according to clause 7 and / or the luminescent device according to clause 20, the system being one or more of the following:

[0207] a. Office lighting system

[0208] b. Home application system

[0209] c. Store lighting system,

[0210] d. Home lighting system,

[0211] e. Accent lighting system,

[0212] f. Spotlight lighting system,

[0213] g. Theater lighting system,

[0214] h. Fiber optic application system,

[0215] i. Projection system,

[0216] j. Self-luminous display system,

[0217] k. Pixelated display system,

[0218] l. Segment display system,

[0219] m. Warning sign system,

[0220] n.Medical lighting application system,

[0221] o. Signage systems, and

[0222] p.Decorative lighting system

[0223] q.Portable system

[0224] r.Automotive applications

[0225] s.Greenhouse lighting system

[0226] t.Display backlight

[0227] u. Transmitter display

[0228] v. Micro LED.

[0229] 22. Use of the composite luminescent particle according to any one of clauses 1 to 6 or the luminescent composition according to clause 7 as a marker, for example, for anti-counterfeiting applications.

[0230] Example

[0231] In the examples, the following particles were used:

[0232] According to the procedure of EP 3623449 A1, LaPO4:50%Tb nanoparticles with ethylene glycol ligands were obtained. The particles were spherical and the smallest size was D 50 The value is 10nm.

[0233] According to the procedure of EP3922698A1, Y2O3:15%Eu nanoparticles are obtained, the particles are in the form of flakes, with a width of less than 1000 nm and a thickness of less than 10 nm.

[0234] Y3Al5O 12 The nanoparticles were obtained according to the procedure of pending application EP22152028, the particles were spherical, with a minimum dimension of D 50 The value is 10nm.

[0235] Comparative Example A: A uniformly mixed luminescent composition of 1:1 LaPO4:50% Tb and Y2O3:15% Eu

[0236] In a glass vial, 100 mg of LaPO4:50% Tb nanoparticles and 100 mg of Y2O3:15% Eu nanoparticles were weighed and dispersed with 5 mL of water. The vial was then sonicated for 90 min. The water was completely evaporated at 105 °C under gentle stirring. The powders were then ground using an agate mortar and pestle and analyzed.

[0237] The emission spectrum shows Eu 3+ Transmitted by Tb 3+ Excitation (IFRET) sensitization ( Figure 1 , dotted line).

[0238] Comparative Example B: A uniformly mixed luminescent composition of 3:1 LaPO4:50% Tb and Y2O3:15% Eu

[0239] In a glass vial, 300 mg of LaPO4:50% Tb nanoparticles and 100 mg of Y2O3:15% Eu nanoparticles were weighed and dispersed with 5 mL of water. The vial was then sonicated for 90 min. The water was completely evaporated at 105 °C under gentle stirring. The powders were then ground with an agate mortar and pestle and analyzed.

[0240] The emission spectrum shows Eu 3+ The emission is improved compared to Example A ( Figure 2 , dash).

[0241] Comparative Example C: Annealing of the Light-Emitting Composition of Example A

[0242] The samples were prepared according to Comparative Example A. The samples were placed in an alumina crucible and transferred to an oven. They were annealed at 600° C. for 2 hours in an air environment and then cooled to room temperature.

[0243] The annealed sample changes from a white powder before annealing to a brown color after the annealing step. The brown coloration suggests that the ions diffused during the annealing process, thereby forming traces of another compound, such as Y2O3:Tb, which has Tb 4+ Impurity ions cause brown coloration. The photoluminescence performance is also significantly deteriorated.

[0244] In further experiments, different annealing temperatures (500, 600, 700, 800, 1000, 1200°C) were investigated in air as well as in a reducing environment setup. The reducing environment annealing was performed using carbon powder in a double crucible setup, where the crucible containing the sample was placed inside a larger crucible containing carbon powder and covered with a lid. In all cases, the annealed samples did not show improved photoluminescence properties compared to Comparative Example A.

[0245] Comparative Example D: Y3Al5O-free matrix 12 :Ce 3+ and Y2O3:Eu 3+ Annealing of the luminescent composition

[0246] In a glass vial, weigh 100 mg YAG:3% Ce 3+ Nanoparticles and 100mg Y2O3:Eu 3+ The nanoparticles were prepared and dispersed in 5 mL of water. The vial was then sonicated for 90 minutes. The liquid was completely evaporated at 105 °C under gentle stirring. The dried powder was then ground using an agate mortar and pestle. The powder was transferred to an alumina crucible and then placed in an oven. The sample was annealed using carbon powder at 1300 °C for 2 hours in a reducing environment in a double crucible apparatus, where the crucible containing the sample was placed inside a larger crucible containing carbon powder and covered with a lid.

[0247] The annealed powder is bright yellow, but Ce 3+ No light emission under excitation ( Fig. 9 dotted line in the figure). 3+ The absence of luminescence suggests Ce 3+ This indicates that Ce 3+ and Eu 3+ The ions are too close to each other.

[0248] Comparative Example E: Y3Al5O-free matrix 12 :Ce 3+ ,Tb 3+ and Y3Al5O 12 :Eu 3+ ,Tb 3+ The glow Annealing of the composition

[0249] In a glass vial, weigh 50 mg of YAG:0.1%Ce 3+ ,50%Tb 3+ Nanoparticles and 100 mg Y3Al5O 12 :20%Eu 3+,30%Tb 3+ The nanoparticles were prepared and dispersed in 5 mL of water. The vial was then sonicated for 90 minutes. The liquid was completely evaporated at 105 °C under gentle stirring. The dried powder was then ground using an agate mortar and pestle. The powder was transferred to an alumina crucible and then placed in an oven. The sample was annealed using carbon powder at 1025 °C for 6 hours in a reducing environment in a double crucible apparatus, where the crucible containing the sample was placed inside a larger crucible containing carbon powder and covered with a lid.

[0250] The annealed powder is light yellow, but Ce 3+ It emits faint light under excitation ( Fig.10 The dotted line in the figure). The weak Ce 3+ Luminous hint Ce 3+ quenching, most likely due to intermetallic charge transfer interactions. This suggests that Ce 3+ and Eu 3+ The ions are close to each other.

[0251] Luminescent particles containing a luminescent material

[0252] Example 1: Annealing of Y2O3:15%Eu Nanoparticles Encapsulated in Silica Matrix

[0253] In a glass vial, 60 mg of Y2O3:15%Eu nanoparticles were weighed. 1 mL of water and 1 mL of ethanol were added to the vial and shaken thoroughly. Then, 50 μL of TEOS was dripped into the vial under gentle stirring. The vial was then ultrasonicated for 5 minutes, after which 1 mL of ammonia solution (32% ammonia water) was slowly dripped into the vial under constant stirring. The vial was stirred for 30 minutes. After stirring, the solvent was completely evaporated by drying at 105°C under gentle stirring. The resulting powder was ground using a mortar and pestle and transferred to an alumina crucible. The crucible was then placed in an oven and annealed at 1000°C for 8 hours in a reducing environment, and then cooled to room temperature, according to the carbon double crucible apparatus discussed above. The powder was ground again using a mortar and pestle and analyzed.

[0254] The annealed sample remained white and showed improved photoluminescence intensity compared to the Y2O3:15%Eu nanoparticles before encapsulation or annealing. Figure 3 As can be seen, the particles of Example 1 are solid lines, and the untreated Y2O3:15%Eu nanoparticles are dotted lines.

[0255] Example 2: Annealing of YAG:1%Ce Nanoparticles Encapsulated in Silica Matrix

[0256] In a glass vial, weigh 30 mg Y3Al5O 12:1% Ce nanoparticles. 1mL of water and 1mL of ethanol were added to the vial and shaken thoroughly. Then, 50μLTEOS was dripped into the vial under gentle stirring. The vial was then ultrasonicated for 5 minutes, after which 1mL of ammonia solution (32% ammonia water) was slowly dripped into the vial under constant stirring. The vial was stirred for 30 minutes. After stirring, the solvent was completely evaporated by drying at 105°C under gentle stirring. The resulting powder was ground using a mortar and pestle and transferred to an alumina crucible. The crucible was then placed in an oven and annealed at 1000°C for 8 hours in a reducing environment, following the carbon double crucible apparatus discussed above, and then cooled to room temperature. The powder was ground again using an agate mortar and pestle and analyzed.

[0257] The annealed sample appears light yellow and exhibits bright photoluminescence (emission spectrum as Figure 4 shown).

[0258] Luminescent particles containing a variety of luminescent materials

[0259] Example 3: Luminescent particles comprising LaPO4:Tb and Y2O3:Eu from a single dispersion

[0260] In a glass vial, 150 mg of LaPO4:50% Tb and 50 mg of Y2O3:15% Eu nanoparticles were weighed and dispersed in 5 mL of water. The vial was then sonicated for 90 minutes. The water was then partially evaporated to a total sample volume of 3 mL. Then, 3 mL of ethanol was added to the vial and mixed thoroughly. 150 μL of TEOS was pipetted and dropped into the vial with gentle stirring. At the end of the addition, the vial was sonicated for 5 minutes.

[0261] Then, 3mL of ammonia solution (32wt.% ammonia water) was slowly added dropwise to the vial under constant stirring. The sample was stirred for another 30 minutes and then dried at 105°C under gentle stirring. The resulting powder was then ground using an agate mortar and pestle and transferred to an alumina crucible. The crucible was placed in an oven. Using the carbon double crucible apparatus discussed above, the sample was annealed at 700°C in a reducing environment for 10 minutes and then cooled to room temperature. The powder was then ground again using an agate mortar and pestle and analyzed.

[0262] The annealed samples remained white. The samples exhibited photoluminescence with improved intensity and energy transfer efficiency: Figure 5 In the graph, the sample of Example 3 is shown as a solid line, and the sample of Comparative Example B is shown as a dotted line. Compared with Comparative Example B, the photoluminescence intensity is improved by about 5 times, and compared with Comparative Example B, the photoluminescence quantum efficiency is improved by 3 times.

[0263] Example 4: Luminescent particles containing LaPO4:Tb and Y2O3:Eu from two dispersions solidified into a single dispersion

[0264] 150 mg of LaPO4:50% Tb nanoparticles were weighed in one glass vial and 50 mg of Y2O3:15% Eu nanoparticles were weighed in another glass vial. 1.5 mL of water and 1.5 mL of ethanol were added to each vial. 75 μL of TEOS was dropped into each vial under gentle stirring, and the dispersion was shaken afterwards. The vials were then sonicated for 5 minutes.

[0265] The dispersion in the vial was mixed and ultrasonicated for 90 minutes. Then, 3 mL of ammonia solution (32% aqueous ammonia) was added to the vial in a slow dropwise manner under continuous stirring. Stirring was continued for another 30 minutes. Drying was performed at 105°C under gentle stirring. The resulting powder was ground using an agate mortar and pestle and transferred to an alumina crucible and annealed at 700°C for 10 minutes in a reducing environment according to the carbon double crucible apparatus discussed above. The sample was cooled to room temperature. The powder was then ground again using an agate mortar and pestle and analyzed.

[0266] The annealed sample remained white and showed improved photoluminescence intensity compared to Comparative Example A, as well as moderate energy transfer efficiency. Figure 6 It can be seen that Example 4 is represented by a solid line and Comparative Example B is represented by a dotted line.

[0267] Example 5: Luminescent particles containing LaPO4:Tb and Y2O3:Eu from two dispersions were cured separately

[0268] 150mg LaPO4:50%Tb nanoparticles were weighed in a glass vial, and 50mg Y2O3:15%Eu nanoparticles were weighed in another glass vial. 1.5mL water and 1.5mL ethanol were added to each vial, and the vial was shaken thoroughly. Then, 75μL TEOS was dripped into each vial under gentle stirring. The vial was then ultrasonicated for 5 minutes, after which 1.5mL ammonia solution (32% ammonia water) was slowly dripped into each vial under constant stirring. Both vials were stirred for 30 minutes.

[0269] After stirring, the dispersions from the two vials were mixed and sonicated for 90 minutes. The liquid was then completely evaporated by drying at 105 °C under gentle stirring. The resulting powder was ground using an agate mortar and pestle and transferred to an alumina crucible. The crucible was then placed in an oven and annealed at 700 °C for 10 minutes in a reducing environment using the carbon double crucible apparatus discussed above, then cooled to room temperature. The powder was ground again using a mortar and pestle and analyzed.

[0270] The annealed sample is still white, showing improved photoluminescence intensity and relatively lower energy transfer efficiency compared to Comparative Example B. Figure 7 In the figure, Comparative Example B is shown as a dotted line, and Example 5 is shown as a solid line.

[0271] Example 6: Luminescent particles containing LaPO4:Tb and Y2O3:Eu from two dispersions at longer stirring times Solidified into a single dispersion

[0272] 150 mg of LaPO4:50% Tb nanoparticles were weighed in one glass vial and 50 mg of Y2O3:15% Eu nanoparticles were weighed in another glass vial. 1.5 mL of water and 1.5 mL of ethanol were added to each vial. The dispersion was shaken thoroughly, and then 75 μL of TEOS was dropped into each vial under gentle stirring. The vials were then ultrasonicated for 5 minutes and stirred for 5 hours.

[0273] After stirring, the dispersions from both vials were mixed and sonicated for 90 minutes. Drying was performed at 105°C with gentle stirring. The resulting powder was ground using an agate mortar and pestle and transferred to an alumina crucible and annealed at 700°C for 10 minutes in a reducing environment as described above for the carbon double crucible apparatus and then cooled to room temperature. The powder was ground again using a mortar and pestle and analyzed.

[0274] The annealed samples remained white and exhibited improved photoluminescence intensity. Figure 8 The sample of Example 6 is shown as a solid line, and the sample of Example 3 is shown as a dotted line. The energy transfer efficiency is improved compared to Example 4. The photoluminescence intensity is improved by about 10 times compared to Comparative Example B, and the photoluminescence quantum efficiency is improved by 4 times compared to Comparative Example B.

[0275] Example 7: Luminescent particles containing YAG:Ce,Tb and Y2O3:Eu from two dispersions were cured separately

[0276] Weigh 30mg of YAG:1%Ce,30%Tb nanoparticles in a glass vial. Weigh 60mg of Y2O3:15%Eu nanoparticles in another glass vial. Add 1mL of water and 1mL of ethanol to each vial. Shake the dispersion thoroughly, then drop 50μL of TEOS into each vial under gentle stirring. Then ultrasonicate the vials for 5 minutes. Then, slowly drop 1mL of ammonia solution (32% ammonia water) into each vial under constant stirring. Stir both vials for 30 minutes.

[0277] After stirring, the dispersions from the two vials were mixed and sonicated for 90 minutes. The solvent was completely evaporated by drying at 105°C under gentle stirring. The resulting powder was ground using a mortar and pestle, transferred to an alumina crucible, and annealed at 1000°C for 8 hours in a reducing environment as described above in the carbon double crucible apparatus, and then cooled to room temperature. The powder was ground again using a mortar and pestle and analyzed.

[0278] The annealed sample is light yellow, showing that the YAG:Ce 3+ Bright photoluminescence under excitation. Fig. 9The emission spectra of Example 7 (solid line) and Comparative Example D (dotted line) when excited at 440 nm are shown. 3+ emission.

[0279] Example 8: Luminescent particles containing YAG:Ce,Tb and Y2O3:Eu from two dispersions at longer stirring times Solidify separately

[0280] Weigh 30mg of YAG:1%Ce,30%Tb nanoparticles in a glass vial. Weigh 60mg of Y2O3:15%Eu nanoparticles in another glass vial. Add 1mL of water and 1mL of ethanol to each vial. Then shake the dispersion thoroughly, and then drop 50μL of TEOS into each vial under gentle stirring.

[0281] The vial was then sonicated for 5 minutes and stirred for 5 hours. After stirring, the dispersion in the vial was mixed and sonicated for 90 minutes, then dried at 105°C under gentle stirring to completely evaporate the solvent. The resulting powder was ground using a mortar and pestle and transferred to an alumina crucible. Using the carbon double crucible apparatus discussed above, the sample was annealed at 1000°C for 8 hours in a reducing environment and then cooled to room temperature. The powder was ground again using a mortar and pestle and analyzed.

[0282] The annealed sample showed a light yellow color. Compared with Example 7, Ce 3+ The emission intensity under excitation decreases.

[0283] Example 9: Luminescent particles containing YAG:Ce,Tb and YAG:Eu,Tb from two dispersions were cured separately

[0284] Weigh 30mg of YAG:0.1%Ce,50%Tb nanoparticles in a glass vial. Weigh 60mg of YAG:20%Eu,30%Tb nanoparticles in another glass vial. Add 1mL of water and 1mL of ethanol to each vial. Shake the dispersion thoroughly, then drop 50μL of TEOS into each vial under gentle stirring. Then ultrasonicate the vial for 5 minutes and stir for 30 minutes. Then, slowly drop 1mL of ammonia solution (32% ammonia water) into each vial under constant stirring. Stir both vials for 30 minutes.

[0285] After stirring, the dispersions from the two vials were mixed and sonicated for 90 minutes. The solvent was completely evaporated by drying at 105°C under gentle stirring. The resulting powder was ground using a mortar and pestle, transferred to an alumina crucible, and annealed at 1025°C for 6 hours in a reducing environment as described above in the carbon double crucible apparatus, and then cooled to room temperature. The powder was ground again using a mortar and pestle and analyzed.

[0286] The annealed sample appears light yellow and shows 3+ Bright photoluminescence under excitation. Fig.10 The emission spectra of Example 9 (solid line), Example 10 (dashed line) and Comparative Example E (dotted line) under excitation at 440 nm are shown. It can be observed that Ce at 440 nm is significantly increased due to iFRET. 3+ Eu under stimulation 3+ Line launch.

[0287] Example 10: YAG:Ce,Tb and YAG:Eu,Tb from two dispersions with lower silica content The luminescent particles are solidified separately

[0288] Weigh 30mg of YAG:0.1%Ce,50%Tb nanoparticles in a glass vial. Weigh 60mg of YAG:20%Eu,30%Tb nanoparticles in another glass vial. Add 0.25mL of water and 0.25mL of ethanol to each vial. Shake the dispersion thoroughly, then drop 12.5μL of TEOS into each vial under gentle stirring. Then ultrasonicate the vial for 5 minutes and stir for 30 minutes. Then, slowly drop 0.25mL of ammonia solution (32% ammonia water) into each vial under constant stirring. Stir both vials for 30 minutes.

[0289] After stirring, the dispersions from the two vials were mixed and sonicated for 90 minutes. The solvent was completely evaporated by drying at 105°C under gentle stirring. The resulting powder was ground using a mortar and pestle, transferred to an alumina crucible, and annealed at 1025°C for 6 hours in a reducing environment as described above in the carbon double crucible apparatus, and then cooled to room temperature. The powder was ground again using a mortar and pestle and analyzed.

[0290] The annealed sample appears light yellow and shows 3+ Bright photoluminescence under excitation. Fig.10 The emission spectra of Example 10 (dashed line), Example 9 (solid line) and Comparative Example E (dotted line) under excitation at 440 nm are shown. It can be observed that Ce at 440 nm is significantly increased due to iFRET. 3+ Eu under stimulation 3+ Line emission. 3+ The emission intensity of the emission was increased compared to Example 9, probably due to less dilution caused by lower silica content. 3+ Line emission is also improved, indicating improved energy transfer at lower silica contents due to the thinner silica shell that separates the donor and emitter nanoparticles.

[0291] Example 11: YAG:Ce,Tb and YAG:Eu,Tb from two dispersions with appropriate silica content The luminescent particles are solidified separately, with higher doping of Tb and Ce and lower doping of Eu, and the mixing ratio is 1:1

[0292] 30 mg of YAG: 0.5% Ce, 75% Tb nanoparticles were weighed in a glass vial. 30 mg of YAG: 5% Eu, 75% Tb nanoparticles were weighed in another glass vial. 1 mL of water and 1 mL of ethanol were added to each vial. Then, 1 mL of ammonia solution (32% ammonia water) was dripped into each vial under constant stirring. The two vials were stirred for 30 minutes. The dispersion was shaken thoroughly, and then 27 μL of TEOS was dripped into each vial under gentle stirring. The vials were then ultrasonically treated for 5 minutes and stirred for another hour. After stirring, the dispersions of the two vials were mixed, stirred for 24 hours, and ultrasonically treated for 90 minutes. Drying at 105°C with gentle stirring allowed the solvent to evaporate completely. The resulting powder was ground with a mortar and pestle, transferred to an alumina crucible, annealed at 1025°C for 4 hours, and then cooled to room temperature. The powder was ground again with a mortar and pestle and analyzed.

[0293] The annealed sample exhibits a clear yellow color and shows 3+ Bright photoluminescence under excitation. Fig.11 The emission spectrum under excitation at 440 nm is shown. It can be observed that Ce at 440 nm is excited due to iFRET. 3+ Eu under stimulation 3+ Line launch.

[0294] Example 12: YAG:Ce,Tb and YAG:Eu,Tb from two dispersions with appropriate silica content The luminescent particles are partially solidified, with higher doping of Tb and Ce and lower doping of Eu, with a mixing ratio of 1:1

[0295] Weigh 30mg of YAG:0.5%Ce,75%Tb nanoparticles in one glass vial. Weigh 30mg of YAG:5%Eu,75%Tb nanoparticles in another glass vial. Add 1mL of water and 1mL of ethanol to each vial. Shake the dispersion thoroughly, then drop 27μL of TEOS into each vial under gentle stirring. After stirring for 30 minutes, drop 0.15ml of ammonia solution (0.3% ammonia water). Stir the vials for 24 hours.

[0296] After stirring, the dispersions in the two vials were mixed and ultrasonicated for 90 minutes. Then, 0.5 mL of ammonia solution (3% ammonia water) was added dropwise under constant stirring, and stirred for another 30 minutes.

[0297] Drying at 105°C with gentle stirring allowed complete evaporation of the solvent. The resulting powder was ground with a mortar and pestle, transferred to an alumina crucible and annealed at 1025°C for 4 hours and then cooled to room temperature. The powder was ground again with a mortar and pestle and analyzed.

[0298] The annealed sample exhibits a clear yellow color and shows 3+ Bright photoluminescence under excitation. Fig.12The emission spectrum under excitation at 440 nm is shown. It can be observed that Ce at 440 nm is excited due to iFRET. 3+ Eu under stimulation 3+ The Eu emission is improved compared to Example 11 due to the partial curing of the silica shell before mixing.

[0299] Example 13: Luminescent particles containing TAG:Ce and TAG:Eu from two dispersions with appropriate silica contents The pellets are partially cured with a mixing ratio of 1:1

[0300] Weigh 30 mg of YAG:0.5%Ce,99.5%Tb (TAG:0.5%Ce) nanoparticles in one glass vial. Weigh 30 mg of YAG:5%Eu,95%Tb (TAG:5%Eu) nanoparticles in another glass vial. Add 1 mL of water and 1 mL of ethanol to each vial. Shake the dispersion thoroughly, then drop 18 μL of TEOS into each vial under gentle stirring. After stirring for 30 minutes, drop 0.15 mL of ammonia solution (0.3% ammonia water). Stir the vials for 24 hours.

[0301] After stirring, the dispersions in the two vials were mixed and ultrasonicated for 90 minutes. Then, 0.5 mL of ammonia solution (3% ammonia water) was added dropwise under constant stirring, and stirred for another 30 minutes.

[0302] Drying at 105°C with gentle stirring allowed complete evaporation of the solvent. The resulting powder was ground using a mortar and pestle, transferred to an alumina crucible and annealed at 1025°C for 4 hours, then cooled to room temperature. The powder was ground again using a mortar and pestle and analyzed.

[0303] The annealed sample exhibits a clear yellow color and shows 3+ Bright photoluminescence under excitation. Fig.13 The emission spectrum under excitation at 440 nm is shown. It can be observed that Ce at 440 nm is excited due to iFRET. 3+ Eu under stimulation 3+ Eu emission is improved over Examples 11 and 12 due to the higher Tb content and lower silica content, and is further improved over Example 11 due to the partial curing of the silica shell before mixing.

Claims

1. A composite luminescent particle, comprising (i) a first luminescent material, which is a rare earth, an S2 configuration ion or a phosphorescent material doped with a transition metal, (ii) a second luminescent material, which is a rare earth, an S2 configuration ion or a phosphorescent material doped with a transition metal, and further comprising (iii) an oxide material coating having a melting point of 700° C. or higher, wherein the oxide material is selected from silicon oxide, aluminum oxide, phosphate or magnesium oxide, in, The D 50 The values ​​are ≥ 1 nm and ≤ 100 μm as measured using a transmission electron microscope (TEM).

2. The composite luminescent particle of claim 1 , wherein the first luminescent material is capable of emitting light within a first wavelength range, and the second luminescent material is capable of absorbing light within a second wavelength range and has an emission spectrum that at least partially overlaps with one or more excitation bands of the first luminescent material, Preferably, wherein the first luminescent material and the second luminescent material are arranged relative to each other to allow non-radiative energy transfer from the second luminescent material to the first luminescent material.

3. The composite luminescent particle of claim 2, wherein the first luminescent material and the second luminescent material form separate domains within the oxide material, wherein the domains have a size, and the smallest size D of the domains is 50 The value is ≥ 0.5 nm and ≤ 100 nm, more preferably ≥ 0.5 nm and ≤ 50 nm, most preferably ≥ 0.5 nm and ≤ 10 nm, as measured using a transmission electron microscope (TEM).

4. The composite luminescent particle according to any one of the preceding claims, wherein the D 50 The value is ≥1 nm and ≤50 μm, more preferably ≥20 nm and ≤10 μm, most preferably ≥50 nm and ≤10 μm, as measured using a transmission electron microscope (TEM).

5. A luminescent composition comprising (i) a first luminescent material, which is a rare earth, an S2-configuration ion or a phosphorescent material doped with a transition metal, (ii) a second luminescent material, which is a rare earth, an S2-configuration ion or a phosphorescent material doped with a transition metal, wherein at least one of the first luminescent material or the second luminescent material is contained in a particle, the particle is coated with (iii) an oxide material having a melting point of 700° C. or higher, wherein the oxide material is selected from silicon oxide, aluminum oxide, phosphate or magnesium oxide, and wherein the D 50 The value is ≥1 nm and ≤100 μm, as measured using a transmission electron microscope (TEM), Preferably, the first luminescent material is capable of emitting light within a first wavelength range, and the second luminescent material is capable of absorbing light within a second wavelength range and has an emission spectrum that at least partially overlaps with one or more excitation bands of the first luminescent material, More preferably, wherein the first luminescent material and the second luminescent material are arranged relative to each other to allow non-radiative energy transfer from the second luminescent material to the first luminescent material.

6. The composite luminescent particle according to any one of claims 1 to 4, or the luminescent composition according to claim 5, wherein the first luminescent material and / or the second luminescent material is selected from oxides, fluorides, nitrides, borates, garnets, molybdates, phosphates, vanadates, chlorides, sulfides, selenides, silicates, aluminates, oxyfluorides, oxychlorides, oxynitrides, oxysulfides, oxyselenides, fluorochlorides, fluorosilicates and fluorobromides, or a combination thereof, Preferably selected from oxides, garnets, phosphates, vanadates, or combinations thereof, More preferably, Y3Al5O 12 、Lu3Al5O 12 , Y2O3, YVPO4, YVO4 or LaPO4, or a combination thereof.

7. The composite luminescent particle according to any one of claims 1 to 4 or 6, or the luminescent composition according to claim 5 or 6, wherein the oxide material is selected from silicon dioxide, aluminum oxide, magnesium oxide and phosphate.

8. A method for obtaining composite luminescent particles, comprising the following steps: a) providing (i) a first luminescent material, which is a phosphorescent material of rare earth, S2 configuration ion or doped transition metal, or a precursor of the first luminescent material; (ii) a second luminescent material, which is a phosphorescent material of rare earth, S2 configuration ion or doped transition metal, or a precursor of the second luminescent material; and (iii) a precursor of an oxide material, wherein the oxide material has a melting point of at least 700° C., wherein the oxide material is selected from silicon oxide, aluminum oxide, phosphate or magnesium oxide, b) mixing the first luminescent material or the precursor thereof, the second luminescent material or the precursor thereof and the precursor of the oxide material, c) curing the precursor of the oxide material to obtain a cured particle, the cured particle comprising the first luminescent material or the precursor thereof, the second luminescent material or the precursor thereof and a coating of the oxide material, and d) heating the solidified particles at a temperature of at least 200°C.

9. The method of claim 8, wherein the first luminescent material is capable of emitting light within a first wavelength range, and the second luminescent material is capable of absorbing light within a second wavelength range and has an emission spectrum that at least partially overlaps with one or more excitation bands of the first luminescent material.

10. The method according to claim 8 or 9, wherein method step b) is carried out in a single step, thereby forming a single mixture.

11. The method according to claim 8 or 9, wherein the method step b) comprises: b1) mixing the first luminescent material or the precursor thereof with a precursor of the oxide material in a first container, and mixing the second luminescent material or the precursor thereof with a precursor of the oxide material in a second container, b2) optionally, at least partially curing at least one of the obtained mixtures, b3) mixing the optionally at least partially cured mixture.

12. A method for obtaining a luminescent composition, comprising the following steps: a) providing (i) a first luminescent material, which is a phosphorescent material doped with a rare earth, an S2-configuration ion or a transition metal, or a precursor of the first luminescent material; (ii) a second luminescent material, which is a phosphorescent material of rare earth, S2 configuration ion or doped transition metal, or a precursor of the second luminescent material; and (iii) a precursor of an oxide material, wherein the oxide material has a melting point of at least 700° C., wherein the oxide material is selected from silicon oxide, aluminum oxide, phosphate or magnesium oxide, b) mixing one of the first luminescent material or the precursor thereof and the second luminescent material or the precursor thereof with a precursor of the oxide material, c) curing the precursor of the oxide material to obtain a cured particle, the cured particle comprising one of the first luminescent material or the precursor thereof and the second luminescent material or the precursor thereof, and a coating of the oxide material, d) mixing said solidified particles with another luminescent material or said precursor thereof, wherein said another luminescent material or said precursor thereof is optionally coated with an oxide material, said oxide material having a melting point of at least 700° C., and e) heating the mixture at a temperature of at least 200° C., The first luminescent material is capable of emitting light within a first wavelength range, and the second luminescent material is capable of absorbing light within a second wavelength range and has an emission spectrum that at least partially overlaps with one or more excitation bands of the first luminescent material.

13. The method according to any one of claims 8 to 12, wherein the first luminescent material or the precursor thereof and / or the second luminescent material or the precursor thereof is provided in the form of particles, and the minimum size D of the particles is 50 The value is ≥ 0.5 nm and ≤ 100 nm, preferably ≥ 0.5 nm and ≤ 50 nm, more preferably ≥ 0.5 nm and ≤ 10 nm, as measured using a transmission electron microscope (TEM).

14. The method according to any one of claims 8 to 13, wherein the precursor of the oxide material is selected from organic silicates, silicon salts, aluminum salts, phosphates and magnesium salts, preferably wherein the salt is selected from nitride salts or chloride salts, and / or the precursor is an orthosilicate, and / or wherein step c) comprises a hydrolysis reaction, preferably wherein the oxide material is silicon dioxide and step c) comprises adding ammonia to cure the precursor of the oxide material.

15. The method according to any one of claims 8 to 14, wherein the heating is at least partially carried out under a reducing environment, and / or wherein the heating comprises heating at a temperature of at least 500°C, preferably at least 600°C, and preferably at a temperature below 2000°C, more preferably below 1500°C, and / or, The heating comprises heating for at least one minute, preferably at least 5 minutes.

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