ENCAPSULATED MATERIALS IN POROUS PARTICLES

Abstract

The invention provides a process for the production of a (particulate) luminescent material comprising particles, especially substantially spherical particles, having a porous inorganic material core with pores, especially macro pores, which are at least partly filled with a polymeric material with a first material embedded therein, wherein the process comprises (i) impregnating the particles of a particulate porous inorganic material with pores with a first liquid (“ink”) comprising the first material and a curable or polymerizable precursor of the polymeric material, to provide pores that are at least partly filled with said first material and curable or polymerizable precursor; and (ii) curing or polymerizing the curable or polymerizable precursor within pores of the porous material, as well as a product obtainable thereby. The first material comprises one or more materials selected from a group of materials comprising organic luminescent materials, rare-earth luminescent materials, organic dye materials, inorganic dye materials, thermochromic materials, photochromic materials, liquid crystal materials, magnetic materials, scattering materials, high-refractive index materials, radio-active materials, contrast agents and therapeutic agents.

Claims

1. A process for the production of a particle material comprising particles having a porous inorganic material core with pores which are at least partly filled with a polymeric material with a first material embedded therein, wherein the process comprises: impregnating the particles of the particulate porous inorganic material with pores with a first liquid comprising the first material and a curable or polymerizable precursor of the polymeric material, to provide pores that are at least partly filled with said first material and curable or polymerizable precursor; and curing or polymerizing the curable or polymerizable precursor within pores of the porous material, wherein the first material comprises one or more materials selected from a group of materials comprising organic luminescent materials, rare-earth luminescent materials, organic dye materials, inorganic dye materials, thermochromic materials, photochromic materials, liquid crystal materials, magnetic materials, scattering materials, high-refractive index materials, radio-active materials, contrast agents and therapeutic agents.

2. The process according to claim 1, wherein before curing or polymerizing but after impregnation the particles, the impregnated particles and possible remaining first liquid are separated.

3. The process according to claim 1, wherein the pores of the porous inorganic material are hydrophobized.

4. The process according to claim 1, wherein the particles have particle sizes (ps) in the range of 1-500 μm, wherein the porous inorganic material comprises one or more of a porous silica, a porous alumina, a porous glass, a porous zirconia, and a porous titania, wherein the pores have mean pore sizes (dp) in the range of 0.1-10 μm, and wherein the precursor comprises a curable acrylate or silicone.

5. The process according to claim 1, wherein the process further comprises applying an encapsulation to the particles obtained after curing or polymerizing.

6. The process according to claim 5, wherein the process comprises providing the encapsulation by at least partly coating the particles with an inorganic coating selected from the group consisting of a silicon containing oxide, an aluminum containing oxide, a zirconium containing oxide, a glass, a titanium containing oxide, a hafnium containing oxide and an yttrium containing oxide, or with an organic coating selected from the group consisting of polyvinyl alcohol, polyacrylate, polysiloxane, polyurethane, polycarbonate, polyimide, polymetacrylate, polystyrene, polyethene, polypropylene, parylene.

7. The process according to claim 5, wherein the process comprises providing the encapsulation by multi-layer coating the particles, wherein the thus obtained multi-layer coating comprises an organic polymer coating and an inorganic coating, or at least two coatings selected from the group of a silicon containing oxide, an aluminum containing oxide, a zirconium containing oxide, a glass, a titanium containing oxide, a hafnium containing oxide and an yttrium containing oxide.

8. The process according to claim 1, wherein the pores of the porous inorganic material core are partly filled with said polymeric material with said first material, and the process further comprises after curing or polymerizing: further impregnating the particles of the particulate porous inorganic material with pores with a second liquid optionally comprising a further material and a curable or polymerizable precursor of a polymeric material, to provide pores that are at least partly further filled with optionally said further material and curable or polymerizable precursor; and curing or polymerizing the curable or polymerizable precursor within pores of the porous material, wherein the optional further material comprises one or more materials selected from a group of materials comprising organic luminescent materials, rare-earth luminescent materials, organic dye materials, inorganic dye materials, thermochromic materials, photochromic materials, liquid crystal materials, magnetic materials, scattering materials, high-refractive index materials, radio-active materials, contrast agents and therapeutic agents.

9. The process according to claim 5, wherein the process comprises one or more of (i) providing the encapsulation by embedding the particles in a light transmissive solid matrix, and (ii) providing the encapsulation by at least partly coating the particles and subsequently embedding the particles in a light transmissive solid matrix.

10. A particle material comprising particles having an porous inorganic material core with pores which are at least partly filled with polymeric material with a first material embedded therein, wherein the first material comprises one or more materials selected from a group of materials comprising organic luminescent materials, rare-earth luminescent materials, organic dye materials, inorganic dye materials, thermochromic materials, photochromic materials, liquid crystal materials, magnetic materials, scattering materials, high-refractive index materials, radio-active materials, contrast agents and therapeutic agents.

11. The particle material according to claim 10, wherein the particles comprise an encapsulation encapsulating at least a part of the core.

12. The particle material according to claim 11, wherein the encapsulation comprises a coating that at least partly coats the particles with an inorganic coating selected from the group consisting of a silicon containing oxide, an aluminum containing oxide, a zirconium containing oxide, a glass, a titanium containing oxide, a hafnium containing oxide and an yttrium containing oxide or with an organic coating selected from the group consisting of polyvinyl alcohol, polyacrylate, polysiloxane, polyurethane, polycarbonate, polyimide, polymetacrylate, polystyrene, polyethene, polypropylene, parylene.

13. The particle material according to claim 11, wherein the encapsulation comprises a multi-layer coating that coats the particles, wherein the multi-layer coating comprises an organic polymer coating and an inorganic coating, or at least two coatings selected from the group of a silicon containing oxide, an aluminum containing oxide, a zirconium containing oxide, a glass, a titanium containing oxide, a hafnium containing oxide and an yttrium containing oxide.

14. The particle material according to claim 10, wherein the particles have particle sizes (ps) in the range of 1-500 μm, wherein the porous inorganic material comprises one or more of a porous silica, a porous alumina, a porous glass, a porous zirconia, and a porous titania, wherein the pores have mean pore sizes (dp) in the range of 0.1-10 μm, and wherein the polymeric material comprises one or more of an acrylate, silicone, or epoxy type polymer, and wherein the encapsulation comprises an inorganic coating.

15. A solid member comprising a solid matrix with the particle material according to claim 10, wherein the particle material being embedded in the solid matrix.

16. A wavelength converter comprising a solid member according to claim 15, wherein the first material comprises an organic luminescent material and/or a rare-earth luminescent material.

17. A lighting device comprising: a light source configured to generate light source light, the particle material according to claim 10, wherein the first material comprises an organic luminescent material and/or a rare-earth luminescent material, configured to convert at least part of the light source light into visible luminescent material light.

18. The lighting device according to claim 17, comprising the wavelength converter, arranged at a zero or non-zero distance (d) from the light source, wherein the lighting device further comprises a second luminescent material, wherein the second luminescent material under excitation with light has another wavelength distribution of the luminescence than the organic luminescent material and/or rare-earth luminescent material.

19. A method for manufacturing a solid member that comprises the particle material according to claim 10, the particle material being embedded in the solid member, the method comprising: receiving a three dimensional model of the solid member, providing a second material comprising the particle material, building up the solid member by depositing layers of the second material on top of each other by means of an additive manufacturing technology according to the received three dimensional model of the solid member.

20. The method for manufacturing a solid member according to claim 19, wherein the particles comprise an encapsulation encapsulating at least a part of the core.

21. The method for manufacturing a solid member according to claim 20, wherein the encapsulation comprises a coating that at least partly coats the particles with (i) an inorganic coating selected from the group consisting of a silicon containing oxide, an aluminum containing oxide, a zirconium containing oxide, a glass, a titanium containing oxide, a hafnium containing oxide and an yttrium containing oxide, or with (ii) an organic coating selected from the group consisting of polyvinyl alcohol, polyacrylate, polysiloxane, polyurethane, polycarbonate, polyimide, polymetacrylate, polystyrene, polyethene, polypropylene, parylene.

22. A structure comprising a glass body, wherein the glass body comprises the particle material according claim 10, wherein the first material comprises at least one or more materials selected from a group of materials comprising thermochromic materials, photochromic materials, liquid crystal materials, scattering materials and high-refractive index materials.

23. A device for indicating a temperature of a body comprising the particle material according to claim 10, wherein the first material comprises at least one thermochromic material.

24. An agent for medical or therapeutic treatment comprising the particle material according to claim 10, wherein the first material comprises one or more materials selected from a group of materials comprising radio-active materials, contrast agents and therapeutic agents.

25. A solar luminescent concentrator comprising a waveguide comprising a translucent matrix having (i) a particle material dispersed therein and/or (ii) a particle material disposed at at least one side thereof, wherein the particle material comprises particles according to claim 10, embedded in the translucent matrix, and wherein the first material comprises one or more materials selected from a group of materials comprising organic luminescent materials, rare-earth luminescent materials and luminescent quantum dots.

26. A photovoltaic generator comprising a photovoltaic cell and a solar luminescent concentrator according to claim 25, wherein the waveguide is associated with the photovoltaic cell, such that, in use, at least some of the light emitted from the particle material passes into the photovoltaic cell to generate a voltage in the cell.

27. A process for the production of a particle material comprising particles having a porous inorganic material core with pores which are at least partly filled with a first material, wherein the process comprises: impregnating the particles of the particulate porous inorganic material with pores with a first liquid comprising the first material, to provide pores that are at least partly filled with said first liquid comprising said first material; and removing the first liquid from the pores of the particulate porous inorganic material, wherein the first material comprises one or more materials selected from a group of materials comprising organic luminescent materials, rare-earth luminescent materials, organic dye materials, inorganic dye materials, thermochromic materials, photochromic materials, liquid crystal materials, magnetic materials, scattering materials, high-refractive index materials, radio-active materials, contrast agents and therapeutic agents, and wherein the process further comprises after removing the first liquid: impregnating the particles of the particulate porous inorganic material with pores with a liquid comprising a curable or polymerizable precursor of a polymeric material and optionally a further material, to provide pores that are at least partly filled with said curable or polymerizable precursor and optionally said further material; and curing or polymerizing the curable or polymerizable precursor within pores of the porous material, wherein the optional further material is selected from a group of materials comprising organic luminescent materials, rare-earth luminescent materials, organic dye materials, inorganic dye materials, thermochromic materials, photochromic materials, liquid crystal materials, magnetic materials, scattering materials, high-refractive index materials, radio-active materials, contrast agents and therapeutic agents.

28. (canceled)

29. The process according to claim 27, wherein the process further comprises applying an encapsulation to the particles, obtained after removing the first liquid, or after curing or polymerizing.

30. The process according to claim 29, wherein the process comprises providing the encapsulation by at least partly coating the particles with (i) an inorganic coating selected from the group consisting of a silicon containing oxide, an aluminum containing oxide, a zirconium containing oxide, a glass, a titanium containing oxide, a hafnium containing oxide and an yttrium containing oxide, or with (ii) an organic coating selected from the group consisting of polyvinyl alcohol, polyacrylate, polysiloxane, polyurethane, polycarbonate, polyimide, polymetacrylate, polystyrene, polyethene, polypropylene, parylene.

31. The process according to claim 29, wherein the process comprises providing the encapsulation by at least partly coating the particles by atomic layer deposition (ALD).

32. A particle material comprising particles having an porous inorganic material core with pores which are at least partly filled with a first material, wherein the first material comprises one or more materials selected from a group of materials comprising organic luminescent materials, rare-earth luminescent materials, organic dye materials, inorganic dye materials, thermochromic materials, photochromic materials, liquid crystal materials, magnetic materials, scattering materials, high-refractive index materials, radio-active materials, contrast agents and therapeutic agents, wherein the pores of the porous inorganic material core are at least partly further filled with a polymeric material with optionally a further material embedded therein, wherein the optional further material comprises one or more materials selected from a group of materials comprising organic luminescent materials, rare-earth luminescent materials, organic dye materials, inorganic dye materials, thermochromic materials, photochromic materials, liquid crystal materials, magnetic materials, scattering materials, high-refractive index materials, radio-active materials, contrast agents and therapeutic agents.

33. (canceled)

34. The particle material according to claim 32, wherein the particles comprise an encapsulation encapsulating at least a part of the core.

35. The particle material according to claim 34, wherein the encapsulation comprises a coating that at least partly coats the particles with an inorganic coating selected from the group consisting of a silicon containing oxide, an aluminum containing oxide, a zirconium containing oxide, a glass, a titanium containing oxide, a hafnium containing oxide and an yttrium containing oxide or with an organic coating selected from the group consisting of polyvinyl alcohol, polyacrylate, polysiloxane, polyurethane, polycarbonate, polyimide, polymetacrylate, polystyrene, polyethene, polypropylene, parylene.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0148] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

[0149] FIGS. 1a-1f schematically depict some aspects of an embodiment of the process and of the luminescent material;

[0150] FIGS. 2a-2f schematically depict some aspects of an embodiment of the lighting device;

[0151] FIG. 3 shows the in-situ impregnation of Trisoperl PSP's with Ebecryl 150. The black interior (non-filled parts) slowly disappears over time;

[0152] FIG. 4 shows a fluorescent microscope image showing that these particles show bright QD emission;

[0153] FIG. 5a shows a HR-SEM image of a cross-section of an ALD-a particle. FIGS. 5b-5d, respectively, show the elemental analysis by EDX of the regions indicated in the HR-SEM FIG. 5a (image spectra 4, 5, 7, respectively).

[0154] FIG. 6a shows the normalized photoluminescence intensity (PL I) as function of time (t, in seconds) for a non-impregnated sample and impregnated sample, in N2 and in air atmosphere. All measurements are performed at 10 W/cm2 blue flux and 100° C.; FIG. 6b shows the normalized photoluminescence intensity (PL I) as function of time for impregnated samples with and without ALD coating, in N2 and in air atmosphere. All measurements are performed at 10 W/cm2 blue flux and 100° C. FIG. 6c shows the normalized photoluminescence intensity (PL I) as function of time (t, in seconds) for impregnated samples with and without ALD coating, in N2 and in air atmosphere. All measurements are performed at 10 W/cm2 blue flux and 100° C.; and also FIG. 6d shows the normalized photoluminescence intensity (PL I) as function of time (t, in seconds) for impregnated samples with and without ALD coating, in N2 and in air atmosphere. All measurements are performed at 10 W/cm2 blue flux and 100° C. Whereas in FIGS. 6b and 6c the curves for “Impregnated ALD-a/c, air” are a continuation in time of the same samples indicated in the same graphs, respectively, as “Impregnated ALD-a/c, N2”, FIG. 6d shows the curve (curve 4) “Impregnated ALD-c, air” which is obtained after the impregnated ALD particles are directly subjected to photoluminescence measurements under air conditions (thus without an earlier measurement of the PL as function of time under N2). The curves in FIGS. 6a-6d are indicated below in table 1A.

[0155]

TABLE-US-00001 TABLE 1A overview of curves in FIGS. 6a-6d FIG. Curve 1 Curve 2 Curve 3 Curve 4 FIG. 6a no impregnation, N2 no impregnation, air impregnated, no ALD, N2 impregnated, no ALD, air FIG. 6b impregnated, no ALD, N2 impregnated, no ALD, air impregnated, ALD-a, N2 impregnated, ALD-a, air FIG. 6c impregnated, no ALD, N2 impregnated, no ALD, air impregnated, ALD-c, N2 impregnated, ALD-c, air FIG. 6d impregnated, no ALD, N2 impregnated, no ALD, air impregnated, ALD-c, N2 impregnated, ALD-c, air FIG. 7a SEM image of a cross-section of an ALD-b particle. The spectra (S1-S3) show the elemental analysis by EDX of the regions indicated in the SEM image (FIGS. 7b-7d, respectively); FIGS. 8a-8b show SEM images of the fill opening of a non-ALD coated PSP batch 1 (8a) and ALD-b coated PSP (8b); FIG. 8c shows a SEM of particles in more detail. The fill openings are clearly visible. FIGS. 9a-9b schematically depict some aspects of an embodiment of the solar luminescent concentrator and the photovoltaic generator; FIGS. 10 schematically depict some aspects of an embodiment of the method for manufacturing a solid member; FIG. 11 shows a fluorescent microscope image showing that these particles show bright organic luminescent material emission; FIG. 12 shows the normalized photoluminescence intensity (PL I) as function of time (t, in seconds) for a non-impregnated sample and impregnated sample, in N2 and in air atmosphere. All measurements are performed at 10 W/cm2 blue flux and 100° C.;. The curves in FIG. 12 are indicated below in table 1B.

TABLE-US-00002 TABLE 1B overview of curves in FIG. 12 Curve 1: no impregnation, N2 Curve 2: no impregnation, air Curve 3: impregnated, no ALD, N2 Curve 4: impregnated, no ALD, air

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0156] FIG. 1a schematically depicts first particles 20 having a porous inorganic material core 21 and pores 22 which can be combined with a liquid comprising curable or polymerizable precursor 111. The liquid is indicated with reference 711. The liquid further comprises a first material 120 and optionally an alternative first material 150. This alternative first material 150 is indicated as discrete items, such as particles, but may however also comprise molecules, like inorganic molecules or organic molecules, that are molecularly dispersed in the liquid 711. The first material 120 and the alternative first material 150 are selected from a group of materials comprising organic luminescent materials, rare-earth luminescent materials, organic dye materials, inorganic dye materials, thermochromic materials, photochromic materials, liquid crystal materials, magnetic materials, scattering materials, high-refractive index materials, radio-active materials, contrast agents and therapeutic agents. In an embodiment, the liquid 711 comprises as liquid components essentially curable or polymerizable precursor 111 and optionally cross-linkers or initiators for polymerization. The particles 20 and the liquid 711 are mixed (stage I), whereby particles with filled pores are obtained (stage II). After filling, excess of liquid 711 may be removed.

[0157] Then, the curable or polymerizable precursor is brought to curing or polymerization. This may for instance be done by providing UV light and/or thermal energy, etc. to the curable or polymerizable precursors. After reaction, stage III is obtained with particles 20 with at least partly filled pores, which are filled with polymeric material 110 with first material embedded therein. For example, in case the first material comprises quantum dots and/or an organic luminescent material, this particulate material is luminescent, and will give light upon excitation by UV and/or blue light, due to the presence of the QDs or organic luminescent material, and therefore this particulate material is herein also indicated as luminescent material 2, or in case of other types of first material 120 it is referred to as particulate material 2. In this stage, the particles 20 are identical to the porous cores 21.

[0158] Optionally, the process may be continued by encapsulating the thus obtained particulate material 2, with one or more of a coating and a host matrix. Embodiments of products thereof are schematically depicted in FIGS. 1b and 1c, respectively. The result of a coating process is shown in stage IV, wherein the particles 20 are enclosed by encapsulation 220, and here in the form of a coating 320. Coating may for instance be performed in a fluid bed reactor with coating precursors that form a coating on the particles 20, optionally after further processing steps.

[0159] FIG. 1b schematically depicts an embodiment wherein a multilayer coating 320 is applied to such material particle 20, here with a first layer 321, directly adjacent to the core, and further remote a second layer 322, directly adjacent to the first layer 321. For instance, the former layer may be a thin inorganic layer, and the second layer may be a thick(er) inorganic layer (or vice versa). Optionally, a plurality of alternating first and second layers may be applied, which may be all organic, all inorganic, or a combination thereof. For example, the multilayer coating comprises alternating first and second layers of an inorganic material, for instance alternating first and second layers of an aluminum containing oxide and a titanium containing oxide, or alternating first and second layers of an aluminum containing oxide and a zirconium containing oxide. The total thickness of the multilayer coating may be in the range of 20-100 nm, more preferably in the range of 30-80 nm. The thickness of the first and second layers may be in the range of 0.2-10 nm, more preferably in the range of 1-5 nm.

[0160] FIG. 1c schematically depicts the particulate material 2 embedded in a matrix 420. Such system may also be indicated as a solid member 100. Just by way of example, this solid member 100 comprises also the alternative first material 150. FIG. 1d schematically depicts an embodiment wherein the particles obtained in stage III are embedded in the matrix 420. The polymeric material (110; see FIG. 1a) can be seen as primary encapsulation, the coating 320 can be seen as secondary encapsulation, and the matrix 420 can be seen as tertiary encapsulation.

[0161] FIG. 1e schematically depicts an example of a material particle 20 with a coating 320 (by way of example a single layer 321, though a multi-layer may also be possible. Here, the first material 120 has been introduced into the pores without a polymerizable or curable precursor. For instance, the liquid with which the first material 120 has been introduced, may have been evaporated before the coating 320 has been applied.

[0162] FIG. 1f schematically depicts an example of a material particle 20 with a coating 220. Here a first part 23 of the pores 22 comprises a first polymeric material 110 with the first material 120 embedded therein. A second part 24 of the pores 22 comprises a second polymeric material 111 with a second material 121 embedded therein. The first polymeric material 110 and the second polymeric material 111 may identical in some embodiments or different in alternative embodiments. The second material may be selected from the same group of materials as the first material. For example, the first material 120 may comprise an organic dye material or an inorganic dye material, and the second material 121 may comprise a liquid crystal material. As liquid crystals, for example polymer dispersed liquid crystals (PDLC) can be used, or LC materials that are switchable by means of UV causing changes in the refractive index (nematics) or changes in the colour (cholesterics) of the material. In case the liquid crystal material is in the ordered phase, it will transmit light and the material particle 20 will have a colored appearance based on the color of the organic or inorganic dye material. In case the liquid crystal material is in the disordered phase, it becomes reflective (as a result of scattering) and the material particle 20 will have a white appearance. The liquid crystal material may be fixed in either ordered or disordered state during manufacturing or application of the material particle 20, for example by controlling temperature or locally applying an electrical or magnetic field. Alternatively, the state of the liquid crystal material and thereby the color appearance of the material particle 20 may be changed dynamically during application of the material particle 20 by applying an electrical or magnetic field to the material particles 20. Alternatively, in the second polymeric material 111 both a LC material and a dye are embedded, the latter having a different color from the dye embedded in the first polymeric material 110. In case the LC material is in the ordered phase, the appearance of the material particle 20 will be determined by the color of the dye embedded in the first polymeric material 110. In case the LC material is in the disordered phase, the appearance of the material particle 20 will be determined by the color of the dye embedded in the second polymeric material 111, due to multiple absorption of light as a result of scattering. Application of such material particles 20 with one or more (organic or inorganic) dyes in a matrix material results in an object from which the appearances can be changed dynamically by means of an external stimulus.

[0163] FIGS. 1a(IV), 1b, 1c, 1e and 1f all show schematically embodiments wherein the (first) coating layer is in contact with the core over 100% of the entire outer surface area (A) of the particle (or core). Note that these material particles 20 comprise inorganic cores 21 with (optionally) a coating or shell 320 surrounding the cores. In the pores of these pores, luminescent nano particles or quantum dots may be available as the first material 120. These nanoparticles may also be core-shell type particles (not specifically depicted). Hence core-shell type quantum dots may be available in the pores of cores that on their turn are coated with a coating or encapsulation (or shell).

[0164] Pore size is indicated with reference dp, which in general indicates a mean dimension of pore width or pore diameter. The particle size is indicated with ps, which in general indicates a mean dimension of particle width, particle length or particle diameter.

[0165] Referring to FIGS. 1A-1E, in case the first material 120 is an organic luminescent material and/or rare-earth phosphor material and/or a quantum dot material, the material particles 20 are luminescent, and will give light upon excitation by for example UV and/or blue light. The solid member 100 may be used as a wavelength converter for lighting applications or as (part of) a solar luminescent concentrator.

[0166] Referring to FIGS. 1A-1E, in case the first material 120 is a thermochromic material, the material particles 20 are particles that will change color when changing its temperature. The solid member 100 may be used as color changing element. Such particles and/or such element can be used in variety of applications, such as in a temperature sensor for use on the (human) skin or inside the (human) body. An alternative application is in temperature indicators, for example in iron soles or for wearable's (photonic textiles). A further alternative application in colour filters or interference filters. A further alternative application is in smart windows, thermochromic displays, or any object obtained by 3D printing techniques.

[0167] Referring to FIGS. 1A-1E, in case the first material 120 is a photochromic material, the material particles 20 are particles that will change color upon exposure to light. The solid member 100 may be used as color changing element. Such particles and/or such element can be used in variety of applications, such as sunglasses or smart windows, or any object obtained by additive manufacturing techniques.

[0168] Referring to FIGS. 1A-1E, in case the first material 120 is a liquid crystal material, the material particles 20 are particles that will transmit or block light, depending on in which phase the LC material is and can be used as a switch. The solid member 100 may be used as switchable element. Such particles and/or such element can be used in variety of applications, such as in switchable pigments in coatings or paints, or any object obtained by 3D printing techniques.

[0169] Referring to FIGS. 1A-1E, in case the first material 120 is a magnetic material, the material particles 20 are magnetic particles. The solid member 100 may be used as a magnetic element. Such particles and/or such element can be used in variety of applications, such as (bio)sensing applications where the magnetic particles are used as biomarkers (in vivo or ex-vivo), for example in lab-on-chip devices. Alternatively, if objects manufactured by additive manufacturing techniques need to be provided with a magnetic functionality, such material particles with magnetic particles can be applied.

[0170] Referring to FIGS. 1A-1E, in case the first material 120 is a scattering material, the material particles 20 are scattering particles. The solid member 100 may be used as a scattering element. Such particles and/or such element can be used in variety of applications, such as lighting applications or to change the optical appearance of an object.

[0171] Referring to FIGS. 1A-1E, in case the first material 120 is a high-refractive index material, the material particles 20 and the solid member 100 may be used in a variety of applications, such as lighting applications or to change the optical appearance of an object.

[0172] Referring to FIGS. 1A-1E, in case the first material 120 is a radioactive material, the material particles 20 and the solid member 100 will prevent the release of the radioactive material to its surroundings. Such particles and/or such element can be used in variety of applications, such as in agents for medical applications for imaging or therapeutic applications.

[0173] Referring to FIGS. 1A-1E, in case the first material 120 is a toxic material, the material particles 20 and the solid member 100 will prevent the release of the toxic material to its surrounding. Such particles and/or such element can be used in variety of applications, such as in medical applications. For example, the toxic material may be a contrast agent for medical applications. FIG. 2a schematically depicts a lighting device 1. The lighting device 1 comprises a light source 10 configured to generate light 11, such as blue or UV light, or both. Here, by way of example two light sources 10 are depicted, though of course more than two, or only one, may be present. Further, the lighting device 1 comprises the luminescent material 2. The (particulate) luminescent material 2 is configured to convert at least part of the light source light 11 into visible luminescent quantum dot light 121, e.g. one or more of green, yellow, orange and red light. Here, a light converter 100 is depicted, such as e.g. depicted in FIG. 1c. By way of example, the lighting device 1 further comprises the second luminescent material 150, which provides upon excitation second luminescent material light or luminescence 151. This luminescence 151 will in general have another spectral light distribution than the visible luminescent quantum dot light 121. All light generated by the lighting device is indicated with lighting device light 5, which in this schematic embodiment comprises visible luminescent quantum dot light 121 and the optional second luminescent material light 151. Note that the luminescent quantum dots, or here the light converter 100, is arranged at a non-zero distance d from the light source(s) 10.

[0174] As indicated above, the inorganic host particles after impregnation with the quantum dots and after curing and/or polymerization may be used as such (i.e. after stage III in FIG. 1a). In such instance, the particles have no coating. However, also in these embodiments the term “core” is applied, though the particle may entirely consist of such core. Optionally the particles are encapsulated (stage IV in FIG. 1A; FIGS. 1B-1D). This may be a coating (stage IV in FIG. 1A; FIG. 1B) i.e. in principle each particle may include a coating around the core: core-coating particles. However, the particles may also be embedded in a matrix, such as a film or body: (FIGS. 1C & 1D) such matrix encapsulates a plurality of the coated cores (FIG. 1C) or a plurality of non-coated cores (FIG. 1D); of course, combinations of coted cores and non-coated cores may also be possible. In each of these embodiments and variants, the pores of the cores enclose quantum dots.

[0175] Here, and also in the schematically drawings 2b and 2c, a module 170 is shown, with a wall 171, a cavity 172, and a transmissive window 173. The wall 171 and the transmissive window 173 here enclose cavity 172. In FIGS. 2a-2c, the transmissive window 173 is used as an envelope, or as part of an envelope. Here, the transmissive window envelopes at least part of the cavity 172. Note that the transmissive window is not necessarily flat. The transmissive window, comprising in embodiments the matrix, may also be curved, like in the embodiment of a TLED or in a retrofit incandescent lamp (bulb).

[0176] In FIG. 2b, by way of example, the second luminescent material 150 is arranged as part of one or more of the light sources 10. For instance, the light source 10 may comprise a LED with the second luminescent material 150 on the dieor dispersed in a (silicone) dome.

[0177] In FIG. 2c, by way of example the second luminescent material 150 is applied as (upstream) coating to the transmissive window 173, which again in this embodiment comprises the light converter 100.

[0178] FIG. 2d schematically depicts an embodiment wherein the luminescent material 2, or in fact the light converter, is directly applied on the light exit face of a light source 10, here e.g. the LED die 17 of a LED.

[0179] Hence, the second luminescent material can e.g. be present in the first polymeric material (110) or the light transmissive solid matrix (420).

[0180] FIG. 2e schematically depicts a light source 10 with a layer of luminescent material 2. For instance, this layer may be arranged on (the surface of) a LED die 111. Other configurations are also possible, like for instance a plurality of LEDs, or other light sources, in contact with (an extended) light converter 100. As indicated above, another term for light converter is wavelength converter. For instance, the light converter may be a dome like light converter, with one or more light sources, especially LEDs, adjacent thereto.

[0181] FIG. 2f shows an LED based light-emitting device according to an embodiment of the invention. The light-emitting device of this embodiment is provided as a retrofit lamp 6107. The phrase retrofit lamp is well known to the person skilled in the art and refers to an LED based lamp having an outer appearance of an older type of lamp which did not have an LED. The lamp 6107 comprises a base part 6108, which is provided with a traditional cap, such as an Edison screw cap or a bayonet cap. Further, the lamp 6107 has a bulb shaped light outlet member 6109 enclosing a cavity 6104. A plurality of LEDs as light sources 6100 are arranged on the base part 6108 within the cavity 6104. A wavelength converting element 6200 is arranged on the inside of the light outlet member 6109, i.e. on the side of the light outlet member facing the cavity 6104.

[0182] The wavelength converting element 6200, may be applied as a coating on the light outlet member. It is also contemplated that the wavelength converting element may be a self-supporting layer, such as a film or sheet standing free from the light outlet member and having any suitable shape. Alternatively, it may be shaped as a hood member covering the LEDs at a certain distance from the LEDs and from the light outlet member. The wavelength converting element 6200 may comprise particulate material 2 embedded in a matrix 420, as shown in FIG. 2c and FIG. 2d, with an organic luminescent material as the first material 120. Alternatively, luminescent quantum dots may be used as the first material 120. Alternatively, a mix of organic luminescent materials and quantum dots may be used as the first material 120.

[0183] The atmosphere within the cavity 6104 may be air, or it may be controlled so as to have a certain composition. For example, the cavity 6104 may be filled with an inert gas such as nitrogen or a noble gas e.g. argon. In embodiments of the invention, the oxygen concentration within the cavity 6104 may be kept at a low level, e.g. at 20% or less, at 15% or less, at 10% or less, at 5% or less, at 3% or less, 1% or less, 0.6% or less, and preferably at 0.1% or less, by total volume of the sealed cavity.

[0184] FIGS. 9a and 9b show an embodiment of a photovoltaic generator 9001 of the present invention. The translucent matrix 9002 of the waveguide of the embodiment is cuboid and can be considered to have a top surface, four lateral surfaces and a bottom surface. FIG. 9a shows a top view of the photovoltaic generator 9001, and FIG. 9b shows a side view of the photovoltaic generator 9001. Particle material 2 with material particles 20 (see FIG. 1a-1f) comprising luminescent quantum dots 120 (see FIG. 1a-1f) are dispersed in the translucent matrix of the waveguide 9002. In an alternative embodiment, the particle material 2 may comprise organic luminescent material(s). The particle material 2 comprises particles 20 having a porous inorganic material core 21 with pores 22 which are at least partly filled with polymeric material 110 with a quantum dots 120 embedded therein (see FIG. 1a-1f). An interference filter 9003 (not shown in FIG. 1a, shown in FIG. 1b) may be disposed on the top surface of the transparent waveguide, and photovoltaic cells 9004 are disposed on two opposing lateral surfaces of the waveguide. White reflective materials 9005 are disposed on the remaining surfaces of the waveguide. The combination of the translucent matrix 9002, reflective walls 9005 and the interference filter 9003 is also referred to as a solar luminescent concentrator. The transparent matrix has (i) particle material comprising luminescent quantum dots dispersed therein and/or (ii) particle material comprising luminescent quantum dots disposed at at least one side thereof. If the translucent matrix has particle material comprising luminescent quantum dots dispersed therein and particle material comprising quantum dots disposed at at least one side thereof, the luminescent quantum dots of the particle material dispersed in the translucent matrix and the luminescent quantum dots of the particle material disposed at at least one side of the transparent matrix may be the same or different luminescent quantum dots. The luminescent quantum dots preferably absorb light in a region of the electromagnetic spectrum, optionally selected from the UV and/or visible and/or infrared region of the electromagnetic spectrum, and emits light at a greater wavelength. The light at the greater wavelength is at an appropriate energy to generate a voltage in the photovoltaic cell. The luminescent quantum dots preferably absorb light in a region of from 300 nm to 1420 nm. Preferably, the maximum absorption peak is within the UV and/or visible and/or infrared region of the electromagnetic spectrum, preferably within the region of 300 nm to 1420 nm. Preferably, the line width of the absorption peak is 50 nm or more, preferably 100 nm or more, more preferably 150 nm or more, most preferably 200 nm or more. Line width is the width at half height of the absorption line in nm, when measured at 25° C. The greater wavelength preferably corresponds to an energy of at least 1.05 times the bandgap energy in the photovoltaic cell. Preferably, there is no or substantially no overlap of the absorption spectrum and the emission spectrum of the luminescent quantum dots in order to reduce the re-absorption of photons emitted by the luminescent material quantum dots. Preferably, the Stokes shift in the inorganic luminescent material is 50 nm or more, more preferably 80 nm or more, more preferably 100 nm or more.

[0185] The translucent matrix may be of any material known to the skilled person, for example, the transparent matrix may comprise a material selected from a glass and a transparent polymer. The transparent polymer may be selected from a poly(methyl methacrylate) polymer (PMMA, which typically has a refractive index of about 1.49) and a polycarbonate polymer (typical refractive index of about 1.58). The glass may be selected from any known transparent inorganic amorphous material, including, but not limited to, glasses comprising silicon dioxide and glasses selected from the albite type, crown type and flint type. Different glasses have different refractive indices and, if desired, the glass can be selected on the basis of its refractive index. For example, a glass of the albite type may have a refractive index of about 1.52. A glass of the crown type may have a refractive index of about 1.49 to 1.52. A glass of the flint type may have a refractive index of from about 1.58 to about 1.89, depending on its density and constituents, as would be appreciated by the skilled person.

[0186] A translucent matrix in the present context includes, but is not limited to, a material that can transmit light at least in a portion of the electromagnetic region in which the luminescent quantum dots absorb light and at least in a portion of the electromagnetic region in which the luminescent quantum dots emit light. It preferably can transmit light at least in part across, optionally across the whole of, the region of 300 to 2000 nm. Optionally, the refractive index of the particle material is 93% to 107% of the refractive index of the translucent matrix, optionally 95% to 105% of the refractive index of the translucent matrix, optionally 98% to 102% of the refractive index of the translucent matrix. The efficiency can be improved when the refractive index of the particle material is the same as or substantially the same as that of the translucent matrix. This avoids scattering of light at the interface between the particle material and the matrix. Translucent materials for use in or as the translucent matrix with a range of refractive indexes are known, and the selection of a suitable material is within the skills of the skilled person.

[0187] The particle material 2 comprising material particles 20 (see FIG. 1a-1f) may be dispersed in the translucent matrix by any appropriate method. For example, the method may comprise providing a liquid precursor to the translucent matrix, dispersing the particle material within the liquid precursor and solidifying the liquid precursor to form the translucent matrix in which the particle material is dispersed. The liquid precursor may, for example, comprise or be a molten form of the material of the solid translucent matrix, and the particle material may be dispersed in the molten material, which is then solidified to form the translucent matrix in which the particle material is dispersed. The liquid precursor may comprise a liquid carrier containing the material of the translucent matrix and the particle material and the liquid carrier may be removed to form the translucent matrix in which the particle material is dispersed; the material of the translucent matrix and the particle material may be present in the liquid carrier as a solution and/or a suspension, for example. Alternatively, if the solid translucent matrix comprises a polymer, the liquid precursor may be a liquid containing an unpolymerised or incompletely polymerised precursor to the polymer and the particle material and the unpolymerised or incompletely polymerised precursor may be polymerised or further polymerised to form the translucent matrix in which the particle material is dispersed.

[0188] In a preferred embodiment of the solar luminescent concentrator, the luminescent quantum dots, comprise a semiconductor material with an indirect bandgap, including, but not limited to, Si and GaP. Such materials have been found to be less likely to reabsorb emitted photons.

[0189] In an embodiment of the invention, a structure comprising a glass body, wherein the glass body comprises particle material 2 comprising material particles 20 (see FIG. 1a-1f). The first material 120 that is present in the pores of the particle material 2 may comprise a thermochromic material, a photochromic materials, a liquid crystal materials, a scattering material, a high-refractive index material, or combinations thereof. For example, the structure may be a window for a building or a door for a building, having a window-glass. By apply an external stimulus to the structure, for example increasing the temperature, the glass may become less transparent when using a liquid crystal material, or change its appearance (color) when using a thermochromic material.

[0190] In an embodiment of the invention, a device for indicating a temperature of a body comprises a particle material 2 comprising material particles 20 (see FIG. 1a-1f), wherein the first material comprises at least one thermochromic material. For example, the device may be a temperature sensor to be used on the human or animal skin, or in de human or animal body. In case the temperature of the skin or body increases above a certain value, determined by the properties of the thermochromic material, the particle material 2 changes from color which may indicate a change in the medical condition on that human or animal. The device can also be used as a temperature indicator on different types of bodies, for example on an iron sole or the bottom of a pan.

[0191] FIG. 10 schematically shows a method 1602 of manufacturing a solid member 100 (see FIGS. 1c and 1d), and in addition a method 1600 of manufacturing a lighting device.

[0192] The solid member 100 can have any shape and may contain one or more openings or holes, depending on the application of the solid member 100. The method 1602 of manufacturing a solid member comprises receiving 1610 a three dimensional model of the solid member. The method 1602 of manufacturing a solid member further comprises building up 1612 the solid member by depositing layers on top of each other by means of an additive manufacturing technology according to the received three dimensional model of the solid member.

[0193] Examples of additive manufacturing technologies are, for example, direct metal laser sintering, selective laser sintering, electron beam melting, fused deposition modeling, 3d printing based on extrusion and additive manufacturing based on using an arc wire, polyjet printing, stereolithography and digital light processing. When such additive manufacturing technologies are used, one can easily optimize the shape of the solid member and any optional openings and/or holes of the solid member. Additive manufacturing allows optimizing the shape of the solid member for its intended application. Also, the above manufacturing method builds up the solid body as a homogeneous component made of (optionally) one material. The use of the particle material according to the invention in the present manufacturing method provides an advantageous approach for introducing functional materials in objects obtained by additive manufacturing technology. When UV curable polymer materials are used, such as in stereolithography or digital light processing, the functional materials can be easily be introduced by mixing it into the photopolymer material. In case techniques are applied that use a powder material, objects with multiple colors can be created, for example. The functional material can be included in the binder material that used in these techniques, e.g. in inkjet printing or polyjet printing, which binder material is usually present in the head of the printing device.

[0194] The method 1600 of manufacturing a lighting device comprises the method 1602 of manufacturing a solid member as a luminescent converter and at least comprises optically coupling 1630 a light source to the solid member. For example, the solid member may be manufactured with one of the above discussed additive manufacturing technologies, after which the solid member is directly applied on the light exit surface of a light source (e.g. a Light Emitting Diode), or alternatively remotely positioned with respect to the light source.

[0195] Optionally, the method 1600 of manufacturing a lighting device comprises providing 1620 another luminescent material as a part of the light source, for example dispersed in a silicone dome on top of an LED. Optionally, the method 1600 of manufacturing a lighting device comprises providing 1622 a module in which one or more LEDs are positioned.

[0196] It is to be noted that in FIG. 10 it seems that specific steps are to be executed in a specific order. The above discussed methods are not limited to this order only. When appropriate, specific steps may be executed in another order, or in parallel to each other. It is further to be noted that the method 1602 of manufacturing a solid member 100 is not limited to application in a lighting device but can be used in any object, device etc.

[0197] Hence, in an embodiment QDs are dispersed in an ink of monomers/oligomers that can be cured upon irradiation or heating or polymerized. Ideally, the QDs are well-dispersed, and the QD-host combination is known to show highly stable behavior under blue flux and elevated temperature (such as between 50 and 150° C., or especially between 75° C. and 125° C.). Macro porous silica with a size of 0.5-500 um and pores of 0.1-10 um are mixed with the QD-ink, and the ink is allowed to fill the micro pores of the silica particles. Filling of the pores may be facilitated by evacuating the porous particles before adding the QD-ink. The filled composite particles are isolated from the mixture, and the ink within the particles is cured or polymerized. The cured or polymerized composite particles are optionally subsequently coated with an inorganic seal material.

[0198] By way of example, some QD-ink combinations are mentioned: [0199] QDs dispersed in acrylates (monomers or oligomers) [0200] QDs dispersed in silicones (mainly oligomers) [0201] QDs dispersed in epoxies (monomers or oligomers) [0202] QDs dispersed in any other curable polymer resin (monomers or oligomers)

[0203] Prior to filling it is preferred to completely dry the porous particles to reduce the water content to a minimum. Typically a sintering step is used to dry the porous silica or other porous material.

[0204] After curing or polymerization of the QD-ink within the (silica) particles the composite particles are isolated. The isolated composite particles are then optionally sealed with preferably an inorganic coating using: [0205] Deposition technique from gas-phase, using a fluidic bed reactor (PVD, ALD, etc.) [0206] Growing an inorganic shell from precursor materials in a chemical (wet chemical or chemical vapor deposition) synthesis

[0207] Alternatively an organic seal material such as an epoxy or perylene or parylene is deposited on the outside of the composite particle.

[0208] Alternatively, the isolated porous particles can be inserted directly (without sealing) into a hermetic host material, such as an epoxy (e.g. DELO Katiobond 686) or low-melting point glass.

[0209] The end result is a sealed composite QD/polymer/inorganic material particle which can be processed further in air, similar to how YAG:Ce phosphors are currently treated. The particles can for example be mixed with an optical grade silicone and then deposited on the LED or substrate.

[0210] In alternative embodiments, other materials than QDs may be used, for example one or more materials selected from a group of materials comprising organic luminescent materials, nanoparticle rare-earth phosphor materials, organic dye materials, thermochromic materials, photochromic materials, liquid crystal materials, nanoparticle magnetic materials, nanoparticle scattering materials, nanoparticle high-refractive index materials, radio-active materials, contrast agents and therapeutic agents. For example, applying a similar method as described above, a sealed composite organic luminescent material/polymer/inorganic material particle or a sealed composite thermochromic material/polymer/inorganic material particle can be produced, etc.

[0211] Below examples especially describe routes wherein porous silica particles (Trisoperl) are first impregnated with QD-acrylic matrix, then filtered to remove excess acrylic, and then cured. After the curing step, the particles may optionally be washed with toluene or other solvent. As expected, it is found that the porous silica particles are filled with acrylic after all these steps.

[0212] First, it was shown that impregnation of porous silica particles with acrylic can be followed in-situ by a microscope: porous silica particles that are non-filled and embedded in a liquid appear black due to scattering. Filled porous silica particles appear transparent. Filling of porous silica particles can therefore nicely be recorded. As examples, Ebecryl 150 and Sylgard 184, a PDMS silicone, were used. porous silica particle within the liquids are black due to scattering, but the porous silica particle with liquid inside the droplet are transparent (hence filled). It is hereby shown that a high viscous silicone such as Sylgard 184 or an acrylate easily fill up the pores of the porous silica particles. In high viscous Ebecryl, it was observed that filling takes roughly 100-500 seconds, in low viscous IBMA (Isobornyl methacrylate) it was observed that filling is a matter of seconds. Eventually, all particles appear transparent.

[0213] FIG. 3 shows the impregnation of Trisoperl PSPs in ebecryl 150 at different time intervals. It is seen that the particles at short time interval still have a partly black interior, which is slowly disappearing over time. In high viscous Ebecryl, it was observed that filling takes roughly 100-500 seconds, in IBMA it was observed that filling is a matter of seconds. Eventually, all particles appear transparent.

[0214] When the in-situ impregnated particles are exposed to UV-light (which can be done under a microscope (“in-situ”) as well), “cracking” within the interior of the particles is observed. This is attributed to shrinkage of the acrylic upon cure (can be up to 10%), and subsequent delamination of the acrylic from the interior walls, creating new scattering pores. For silicones the shrinkage seems to be much smaller (few percent) and the cracking is not observed.

[0215] An embodiment of the impregnation process was performed, consisting of the following step: [0216] 1—Mix QDs (0.1-1 wt. %) in ebecryl 150 or a 80/20 mixture of IBMA/HDDA [0217] 2—Add 0.5% wt irgacure (optional) [0218] 3—Add 1 gram of trisoperl porous silica particles to 5 gram of the QD-acrylic mixture [0219] 4—Gently stir/shake for 10 minutes [0220] 5—Apply the QD-acrylic-porous silica particle mixture on a filter, which is placed on a Buchner funnel [0221] 6—Apply vacuum to the funnel for 1-10 minutes [0222] 7—Flush the porous silica particles on the filter with ethanol, heptanes, toluene, or another solvent (optional) [0223] 8—Remove the powder from the filter [0224] 9—Spread the powder over a glass plate or vial and cure with UV under N2 flow [0225] 10—Disperse the cured powder in toluene and apply an ultrasound treatment [0226] 11—Remove the toluene, resulting in the impregnated powder.

[0227] Amongst others, 0.1% wt QDs and 0.5% wt. PI (photo initiator), which are impregnated and cured according to step 1-9 (but without step 7).

[0228] In a further example, Trisoperl particles were impregnated according to step 1-11, without step 7. In this case, a 0.1% wt dispersion of Crystalplex QDs in heptanes was made in IBMA/HDDA (5 g) to which 1 gram of porous silica particles were added, and 0.5% wt photoinitiator (irgacure). After filtration the powder was cured for 10 minutes in an N2 flow with UV light. This results in a sticky powder, which was converted into a loose powder of individual porous silica particles by dispersing it in toluene and giving it a 1 minute US treatment. The toluene was removed and the particles were applied on a glass disc for in-situ investigations under the microscope. When these porous silica particles were brought into contact with Ebecryl, the particles did not show re-filling, but were transparent instantaneously. In addition, some particles exhibit a brown color and cracks, which indicates that the acrylate within the particles is cured, and does not re-fill again. This is explained by the fact that porous silica particles that are well impregnated and cured will have clogged pores that does not allow for a (quick) secondary fill with ebecryl. However, it is sometimes observed that these can be re-filled with toluene, which is not surprising in view of its low viscosity.

[0229] The fluorescent microscope image (FIG. 4) shows that these particles show bright QD emission. Here, Trisoperl porous silica particles impregnated with 0.1% wt QDs in IBMA/HDDA. The porous silica particles were cured and given an ultra sonic treatment in toluene, after which they were spread out on a glass plate, to which a droplet of Ebecryl was added.

[0230] Different silica particles were tested on their suitability of the present process for making the luminescent material. A non-exhaustive list is given in table 2 below:

TABLE-US-00003 TABLE 2 listing of some silica particles that were used in the experiments Particle size (μm) Pore size (nm) Type 1 30-70 100-450 Type 2 About 30 About 160 Type 3 About 30 150-200

[0231] Especially type 3 are very spherical particles (circularity over 0.95), which facilitates the application of a coating on the particles (if desired).

[0232] Stability measurements on the quantum dot filled particulate porous luminescent material were performed under N2 flow. It appeared that the stability of the QDs in the porous silica particles is very similar to the same commercial QD-based nanoparticles directly dispersed in IBMA/HDDA without porous particles. However, the present luminescent material is easy to handle, can be used in state of the art coating processes or matrix dispersing processes, and does not need oxygen and/or water free environments. It also appears that the quantum efficiency of the QD's in the pores is about the same or even the same as those of the original quantum dots.

[0233] Mercury porosimetry was used to determine the degree to which the pores of the silica particles were filled after the impregnation step. First, it was determined that the Trisoperl particles without any treatment have a specific pore volume of 1.09 cm3/g powder. Second, it was determined the specific pore volume of Ebecryl and IBMA/HDDA filled Trisoperl particles without a solvent washing step (step 7) is 0.06 cm3/g (Ebecryl) and 0.00 cm3/g (not detectable) (IBMA/HDDA), respectively. This confirms that the Trisoperl particles are almost complete filled with cured acrylic ink.

[0234] Using the impregnation method described above (using Buchnel funnel), subsequently an ALD coating around the impregnated particles was applied. In some experiments, the coating comprises 50 nm of alumina. With ALD coating, the stability of QDs in air is improved (relative to impregnated particles without acoating). With ALD coating, it is shown that the QD stability in air is similar to the stability in Nitrogen, which shows that the ALD coating is successfully applied, and keeps water/air outside the impregnated particles. The experiments are described in further detail below.

Example 1 Preparation of Impregnated Particles

[0235] Trisoperl particles were impregnated according as follows: 1 gram of 5% wt dispersion of Crystalplex QDs in heptanes was added to IBMA/HDDA (5 g). This results in a 1% wt dispersion QDs in IBMA/HDDA, to which 1 gram of PSPs were added, and 0.5% wt photoinitiator (irgacure 184). The powder-acrylate mixture was put on a Buchner funnel, and filtrated for a few minutes in the glovebox. After filtration the powder was cured for 4 minutes with UV light in the glovebox. This results in a sticky powder, which was converted into a loose powder of individual PSPs by dispersing it in toluene and giving it a 15 minute US treatment in a close vial, hence no contact with ambient air. Next, the toluene was removed in the glovebox, by decanting, followed by evacuation of a few hours to remove all toluene. FTIR measurements show that the acrylic has a 95% conversion rate, which means a nearly complete curing of the acrylate. A subset of these particles was mixed into ebecryl 150 for QE and stability measurements. The QE of these QDs was measured to be 51% and 52% for two different impregnation experiments. The QE of the QDs in HDDA/IBMA without impregnation was measured at 69%. This means there is a loss in QE upon impregnation, curing, and bringing into a second matrix. The reason for this drop is unclear, but likely due to the additional processing steps. The QE data are summarized in Table 3.

Example 2 Plasma Enhanced ALD on Impregnated PSP

[0236] 50 mg of the impregnated PSP (batch 1) was spread out over a silicon wafer (outside the glovebox), and inserted into the Emerald chamber (for plasma enhanced ALD) of an ASM dual chamber ALD system. A 50 nm alumina layer was applied using the plasma-enhanced ALD process at 100 C, using TMA (trimethylaluminium) and O2 as reactive gasses. After deposition, the powder was harvested and mixed into Ebecryl 150 (with 1% wt irgacure 184) to make cured films of the ALD-coated PSP's in a secondary matrix. As described above in example 1, reference samples of the same impregnated PSP's without ALD were also made, in addition to films of plain QDs in IBMA/HDDA (no impregnation). In all cases, the samples consisted of a 100 um acrylic layer, in between two glass plates. The QE of the ALD-coated PSP's using plasma enhanced ALD (called sample ALD-a from here on) had a QE of 50%, which is the same as before ALD coating (batch 1, 52%). The ALD coating thus has (almost) no impact on the QE of the QDs.

TABLE-US-00004 TABLE 3 overview of QE data on various films: PL QE Description ALD (%) QDs in IBMA/HDDA (no impregnation) No ALD 69 QDs in IBMA/HDDA impregnated PSP - No ALD 52 batch 1 QDs in IBMA/HDDA impregnated PSP - No ALD 51 batch 2 ALD-a coated PSP batch 1 Plasma @ 100° C. 50 ALD-b coated PSP batch 1 Thermal @ 150° C. 31 ALD-c coated PSP batch 2 Thermal @ 100° C. 33

[0237] The QE's are relatively low. This is due to the fact that commercial QD material was used with a relative low initial QE. Much higher QE's are possible when QDs of a better quality are applied, but those are not readily commercially available on a large scale.

[0238] A small part of the ALD coated particles from ALD-a was used to make cross-sections and investigate in SEM. FIG. 5a shows a SEM image of PSP's with ALD-a coating. In the prepared Schliffs (cross-sections) some of the particles were not fully embedded in the epoxy carrier. As a result the images provide a 3D view on the particle, where 3 different regions can be identified. In addition, these particles offered the possibility to analyze the coating of the particles using selected area EDX. The first region is the interior of the PSP (e.g. at location of spectrum 7), where the porous structure can be clearly identified. The EDX recorded at location “spectrum 7” is also shown, in which only silicon can be observed, no aluminium. The second region is the outside of the PSP, where a more dense silica shell is present (called “egg-shell” from here on). It is known from these particular PSPs that they have a dense silica shell around the particle, except for some “fill-openings” (see also SEM images in appendix). An EDX spectrum recorded at this region (spectrum 5) indeed shows only silicon. The third region that can be identified is an additional thin layer on top of the “egg shell”, which is the aluminium oxide layer applied by ALD. The EDX spectrum recorded at this location (spectrum 4) clearly shows that indeed aluminium is present, confirming that the ALD coating has resulted in deposition of alumina on the shell of the particles. In the SEM image it can be seen that this second layer is very conformal. The fact that at the top part (at location of spectrum 5) the silica egg shell is exposed is attributed to the grinding applied to make the cross-sections (preparation of schliffs).

[0239] From the SEM image and EDX it appears that the alumina coating is quite conformal and also covers the fill openings. However, the SEM may not be very quantitative in determining the exact coverage by alumina, and also may not provide statistical information to which extent all particles are coated equally well. XPS (X-ray photo spectroscopy) is a technique which probes the outer few nm of substrates on elemental composition. An analysis of XPS on the plasma-enhanced ALD coated particles (ALD-a) are summarized in Table 4, where a comparison is made with an uncoated PSP (no ALD batch 1). The uncoated particles show only silica, and some Cd, Zn, and Se from the QDs. The organic material likely originates from contamination from the substrate, or acrylic exposed to the outside. In contrast, the ALD-coated particles display primarily aluminium oxide as inorganic coating, and most importantly no silicon could be detected. Since the detection limit of silicon in this measurement is ˜0.1%, it is concluded that at least 99% of the surface has been coated with aluminium oxide.

TABLE-US-00005 TABLE 4 summary of XPS measurements on sample ALD-a, and a blanc (no ALD coating). Numbers give the atomic weight %, and sum up to ~100%: Al 2p C 1s Cd 3d O 1s Se 3p3 Si 2p Zn 2p3 Peak 74.2 284.8 103.5 Present as Al2O3 org SiO2 Blanc — 46 0.5 39 0.3 14 0.81 ALD-a 22 32 — 47 — — 0.03

[0240] Since the ALD coating is applied to improve the stability of QDs in air, the photoluminescence stability was measured before and after impregnation, and with and without ALD coating. All measurements were performed under the same conditions of 10W/cm2 blue flux (using a 450 nm blue laser), and 100° C. temperature. The fast drop seen in these measurements after ˜5000 seconds is due to the raise in temperature from 25° C. to 100° C.; the thermal quench causes a quick drop in PL intensity.

[0241] FIG. 6a shows the stability curves of the reference sample of QDs in IBMA/HDDA without impregnation (QE of 69%), and with impregnation (batch 1, QE of 52%). The samples were first measured in a flow of nitrogen, with the 100 μm QD film still sandwiched between two glass plates to avoid any diffusion of water/air into the sample. The curves show fairly similar behavior, with a degradation rate after ˜250.000 seconds of 1.3E-6 and 1.5E-6 s-1 respectively. Such degradation under these conditions is very typical for this combination of commercial QDs and IBMA/HDDA acrylic. The results shows that the impregnation process as such has no effect on the QD PL stability. There is a difference visible between the two curves initially; the curve 3 shows more photobrightening than the curve 1. Photobrightening is a phenomenon observed frequently for QDs, is not well understood, and also beyond the scope of this invention. Hence, we will not go into details of this photobrightening effect further.

[0242] When both samples are measured in air (where the top glass plate was removed to allow water/air to quickly reach the laser spot) the samples show a dramatic increase in degradation rate. The impregnated sample appears to behave slightly better than the sample without impregnation, which may be attributed to the longer diffusion length of water/air into the silica particles.

[0243] FIG. 6b shows the same stability curves of the impregnated sample without ALD in N2 and in air, and in addition the stability curve of the impregnated samples with Plasma Enhanced ALD coating (sample ALD-a). First, in N2 atmosphere it is observed that the stability of the impregnated sample is not affected by the ALD coating; after 250.000 seconds it shows a very similar degradation rate of 1.4E-6 s-1. Fluorescence microscopy shows that the total impregnated sphere luminesces: there is no ‘dead skin’ caused by the deposition process. Most importantly, a clear difference in stability between the ALD coated and non-coated sample is observed when measured in air. The ALD-coated sample shows a degradation rate in air that is very similar to that in N2 (again 1.4E-6). The fact that the degradation rate in N2 and air are so similar, provides evidence for the fact that the ALD coating is very effective in keeping water/air outside the silica particle.

Example 3 Thermal ALD @ 150 C on Impregnated PSP

[0244] 30 mg of the impregnated PSP (batch 1) was spread out over a silicon wafer (outside the glovebox), and inserted into the Pulsar chamber (for thermal ALD) of an ASM dual chamber ALD system. A 50 nm alumina layer was applied using the thermal ALD process at 150 C, using TMA (trimethylaluminium) and O3 as reactive gasses. After deposition, the powder was harvested and mixed into Ebecryl 150 (with 1% wt irgacure 184) to make cured films of the ALD-coated PSP's in a secondary matrix. The QE of the ALD-coated PSP's using thermal ALD at 150° C. (called sample ALD-b from here on) had a QE of 31%, which is a drop of 20% compared to before ALD coating (batch 1, QE of 52%).

[0245] A small part of the thermal ALD coated particles from ALD-b was used to make cross-sections and investigate in SEM. FIG. 7a shows a SEM image of PSP's with ALD-b coating. In the prepared Schliffs (cross-sections) some of the particles were not fully embedded in the epoxy carrier. As a result the images provide a 3D view on the particle, where 3 different regions can be identified. In addition, these particles offered the possibility to analyze the coating of the particles using selected area EDX. The first region is the interior of the PSP (at location of spectrum 3(S3) (FIG. 7d)), where the porous structure can be clearly identified. The EDX recorded at location “spectrum 3” is also shown, in which only silicon can be observed, no aluminium. The second region is the outside of the PSP, where a more dense silica shell is present (called “egg-shell”). It is known from these particular PSPs that they have a dense silica shell around the particle, except for some “fill-openings” (see also SEM images in appendix). An EDX spectrum recorded at this region (spectrum 2; S2 (FIG. 7c)) indeed shows only silicon. The third region that can be identified is an additional thin layer on top of the “egg shell”, which is the aluminium oxide layer applied by ALD. The EDX spectrum recorded at this location (spectrum 1; S1 (FIG. 7b)) clearly shows that indeed aluminium is present, confirming that the ALD coating has resulted in deposition of alumina on the shell of the particles. In the SEM image it can be seen that this alumina layer is very conformal. The fact that at the top part (at location of spectrum 2 (S2)) the silica egg shell is exposed is attributed to the grinding applied to make the cross-sections (preparation of schliffs).

[0246] As mentioned above, the PSP are covered by a dense “egg shell” of silica, and have a few so-called fill openings per particles, which allows impregnation of the particles by the QD-acrylic ink. To ensure a complete seal of the PSP, also the fill-opening needs to be coated with alumina. FIGS. 8a-8b show SEM images of such fill openings of PSPs that are not coated with ALD (FIG. 8a, PSP batch 1) and of PSPs that are coated with thermal ALD (FIG. 8b, ALD-b). The non-coated PSP clearly shows that the egg-shell (bright ring) is discontinuous at this opening (in SEM, a bright appearance reflects a high density of inorganic material). The ALD-coated sample shows that the fill-opening has been coated by alumina, and that the alumina actually protrudes into the pores. It is known that ALD coatings can be very conformal because the molecular precursors can diffuse/penetrate into small pores (such as the 200 nm pores here). For that reason, the overall alumina deposition in this porous area of the fill opening is likely to be higher than on top of the egg shell (which is rather smooth), which can be qualitatively recognized by the relatively “thick” brighter appearance of the outer part of the fill opening compared to the coating around the egg shell. It is anticipated that the filling of these pores by ALD coating is beneficial to obtain a well sealed PSP.

Example 4 Thermal ALD @ 100 C on Impregnated PSP

[0247] 100 mg of the impregnated PSP (batch 2) was spread out over a silicon wafer (outside the glovebox), and inserted into the Pulsar chamber (for thermal ALD) of an ASM dual chamber ALD system. A 50 nm alumina layer was applied using the thermal ALD process at 150° C., using TMA (trimethylaluminium) and O3 as reactive gasses. After deposition, the powder was harvested and mixed into Ebecryl 150 (with 0.5% wt irgacure 184) to make cured films of the ALD-coated PSP's in a secondary matrix. The QE of the ALD-coated PSP's using thermal ALD (called sample ALD-c from here on) had a QE of 33%, which is a drop of 20% compared to before ALD coating (batch 2, 51%). This, and previous example show that thermal ALD causes a substantial drop in QE, which cannot be attributed to solely temperature, since ALD-a (plasma enhanced) was also performed at 100° C. The ozone used for thermal ALD could be the cause for the drop in QE, but this was not investigated further.

[0248] From the edx in example 3 it is not conclusive that the aluminium oxide coating is 100% conformal, neither does it give statistical information over all particles. An analysis of XPS on thermal-enhanced ALD coated particles at 100° C. (a duplo experiment of ALD-c) shows that no silica can be observed anymore after alumina deposition. It is concluded that both plasma enhanced and thermal ALD are able to conformally coat the surface of these porous silica particles with at least 99% coverage.

[0249] Since the ALD coating is applied to improve the stability of QDs in air, the photoluminescence stability was measured before and after impregnation, and with and without ALD coating. All measurements were performed under the same conditions of 10 W/cm2 blue flux (using a 450 nm blue laser), and 100 C temperature.

[0250] The stability of impregnated versus non-impregnated samples was discussed in example 2, and showed that impregnation has no influence on the QD PL stability in N2. However, in air, a dramatic degradation was observed for both cases. FIG. 6c summarizes the results of impregnated PSP without ALD coating (batch 1, also shown in example 2), and with thermal ALD coating (ALD-c). The curve 3 in FIG. 6c shows that the PL stability of QDs is not affected by the ALD coating, since it is very similar as compared to without ALD coating (curve 1). In addition, it is clear that the sample with ALD coating shows a very similar decay rate in N2 as compared to air after 250.000 seconds (1.3E-6 and 1.9E-6 s-1 respectively), whereas the non-ALD samples shows much worse stability in air compared to nitrogen. Again, it is concluded that also a thermal ALD coating is very effective in keeping water/air outside the porous silica particles.

[0251] FIGS. 6b and 6c show the curves (curve 3 in both figures) for “Impregnated ALD-a/c, air” which are in fact a continuation in time of the same samples indicated in the same graphs, respectively, as “Impregnated ALD-a/c, N2”. Only the starting point is again at 0 seconds. Note that the end intensity of the N2-curve (curves 3) is about equal to these starting intensity of the air-curves (curves 4). This is also the reason that the air curves do not show the above-mentioned photobrightening. FIG. 6d shows the curve (curve 4) “Impregnated ALD-c, air” which is obtained after the impregnated ALD particles are directly subjected to photoluminescence measurements under air conditions (thus without an earlier measurement of the PL as function of time under N2). Here, again the initial photobrightening is perceived.

[0252] As indicated above, it is concluded that also a thermal ALD coating is very effective in keeping water/air outside the porous silica particles. Hence, an alumina ALD coating was applied to the particulate porous inorganic material, to allow a good analysis of the shell by EDX after coating (an alumina coating on the silica particle may be easier analyzed than a silica coating on the silica particles). However, a silica coating can be applied by an exact same ALD procedure.

[0253] The HR-SEM images also show that there is hardly any contamination of acrylics on the outside of the particles. The shell and ALD coating are fairly smooth. Here, a stationary ALD coating technique (powder on a wafer) has been used, which already gives very promising results. Powder coating using eg fluidized bed ALD should give at least similar, if not better results. In addition, powder coating ALD should also enable the coating of larger amounts of powder. Coating of multi-gram powder batches are known in the field.

[0254] Note that the invention is not limited to coatings (or shells) on the cores obtained by the ALD process. Also other processes may be applied.

Example 5: Example Impregnation of Trisoperl Particles with Low Molecular Weight Silicone

[0255] Commercial QDs from crystalplex were modified with a siloxane ligand as described in PCT/IB2013/059577, which is herein incorporated by reference). The ligand used was a 5000 Mw siloxane molecule (AB109373, viscosity ˜100 cSt.) with an amine functional group in the side chain, where the amine group was first converted into a carboxylic acid as described in PCT/IB2013/059577 before ligand exchange. The ligands bind to the QD surface through the carboxylic acid, and the siloxane ligands make the QDs miscible into low molecular weight silicones (below 100 cSt.).

[0256] After ligand exchange the QDs were purified once by adding 1 ml heptane and 2 ml of ethanol to 500 ul of QD-ligand mixture (˜1% wt QDs). The QD pellet was redispersed in 250 ul heptanes (hence 2% wt QDs). The 250 ul purified QDs in heptane was added to 0.5 gram of AB109380 (25-35% Methylhydrosiloxane-dimethylsiloxane copolymer; viscosity 25-35 cSt.) which gave a transparent mixture (not possible without the siloxane ligand).

[0257] To 2 gram of AB109356 (Polydimethylsiloxane, vinyldimethylsiloxy terminated; viscosity 100 cSt.), 4 ul of a 100 times diluted solution of a platinum catalyst in xylene (AB146697 (Platinum-divinyltetramethyldisiloxane complex; (2.1-2.4% Pt)) was added. The QD-AB109380 mixture and the Pt-109356 mixture were combined and vigorously stirred for a few minutes, resulting in a clear and transparent curable QD-silicone mixture (0.2% wt QDs).

[0258] To the mixture, 0.5 gram of trisoperl particles were added, and mixed for 1 minute to allow impregnation. The QD-silicone-trisoperl mixture was put on the filter of a Buchner funnel, and evacuated for 5 minutes. The excess QD-silicone liquid was removed in this manner, and a fairly dry but slightly sticky powder remained on the Buchner funnel. The resulting impregnated powder was investigated under the microscope, and from the bright field image it was concluded that the particles were properly impregnated with the QD-silicone liquid (not a black but shiny appearance). In fluorescence microscopy, bright fluorescence from the impregnated particles is observed.

[0259] Next, the trisoperl particles impregnated with the QD-silicone mixture were cured. It can be observed that the shiny appearance in the bright field image partly disappears after 5 minutes curing, and completely disappears after 90 minutes curing. After 90 minutes curing the particles have a black appearance, which is attributed to shrinkage of the silicones upon curing (which is more pronounced for low molecular weight silicones as compared to high molecular weight silicones), which results in “cracking” within in the pores. The cracks cause scattering of the light, giving the black appearance (also observed for acrylate filled particles).

[0260] Finally, the cured impregnated trisoperl particles were brought mixed into toluene and sonicated for 2 minutes. The ultrasonic treatment caused the particles to de-agglomerate into a fine dispersion of impregnated particles in toluene. After the ultrasonic treatment the particles were brought into Ebecryl 150 (a high viscous acrylate). Bright field microscopy images of the cured impregnated trisoperl particles showcase a black appearance, which remained. In other words, no re-filling of the porous particles is observed (which causes the particles to become non-scattering). For non-impregnated particles, re-filling is observed within tens of seconds. For the silicone impregnated particles this was not the case.

[0261] Fluorescence microscopy of the impregnated and cured trisoperl shows uniform luminescence over the particle for all particles. In summary, it is also shown that the trisoperl particles can impregnated with a curable QD-silicone mixture, cured, and washed with the ultrasonic treatment in toluene resulting in a fine de-agglomerated powder.

[0262] AB109356 refers to Polydimethylsiloxane, vinyldimethylsiloxy terminated; viscosity 100 cSt.; AB109380 refers to 25-35% Methylhydrosiloxane-dimethylsiloxane copolymer; viscosity 25-35 cSt; AB146697 refers to Platinum-divinyltetramethyldisiloxane complex in xylene; (2.1-2.4% Pt). These chemicals were purchased from ABCR.

Example 6 Preparation of Impregnated Particles

[0263] Trisoperl particles were impregnated according as follows: Lumogen F305 organic luminescent material from BASF was added to IBMA/HDDA (80/20 ratio by weight) in an amount of 0.1% wt. and mixed. Toluene (30% wt.) was added to the mixture for dilution. Subsequently, trisoperl particles were added, and 0.5% wt photoinitiator (irgacure 184). The powder-acrylate mixture was put on a Buchner funnel, and filtrated for a few minutes in the glovebox. After filtration the powder was cured for 4 minutes with UV light in the glovebox. This results in a sticky powder, which was converted into a loose powder of individual trisoperl particles by dispersing it in toluene and giving it a 15 minute ultra-sound treatment in a close vial, hence no contact with ambient air. Next, the toluene was removed in the glovebox, by decanting, followed by evacuation of a few hours to remove all toluene. A subset of these particles was mixed into ebecryl 150 for QE and stability measurements. The QE of this organic luminescent material was measured to be 89% and 96% for two different impregnation experiments. The QE of this organic luminescent material in HDDA/IBMA without impregnation was measured to be in the range of 90 and 95%. This means there is a small loss in QE upon impregnation, curing, and bringing into a second matrix. The reason for this drop is unclear, but likely due to the additional processing steps. The QE data are summarized in Table 5

TABLE-US-00006 TABLE 5 overview of QE data of the organic luminescent material (OLM) on various films PL Description ALD (QE %) OLM in IBMA/HDDA (no impregnation) (Batch 1) No ALD 92%. OLM in IBMA/HDDA (no impregnation) (Batch 2) No ALD 95%. OLM in IBMA/HDDA Impregnated PSP (Batch 1) No ALD 89%. OLM in IBMA/HDDA Impregnated PSP (Batch 2) No ALD 96%.

[0264] The fluorescent microscope image (FIG. 11) shows that these particles show bright organic luminescent material emission.

[0265] FIG. 12 shows the stability curves of the reference sample of organic luminescent material in IBMA/HDDA without impregnation (QE of 90-95%), and with impregnation (batch 1, QE of 89%). The samples were first measured in a flow of nitrogen, with the 100 μm QD film still sandwiched between two glass plates to avoid any diffusion of water/air into the sample. The curves 1 and 3 show fairly similar behavior and the observed degradation is in line with expectations for the conditions at which the samples were tested, i.e. at 10 W/cm2 blue flux and 100° C. (i.e. an accelerated test). The results show that the impregnation process as such has hardly an effect on the QD PL stability. When both samples are measured in air (where the top glass plate was removed to allow water/air to quickly reach the laser spot) the samples show a dramatic increase in degradation rate. The impregnated sample appears to behave better than the sample without impregnation, which may be attributed to the longer diffusion length of water/air into the trisoperl particles.