Inorganic bonding devices and structures

Abstract

Inorganic coatings can be applied to join optically scattering particles or components. Optically scattering particles joined via the inorganic coating can form a three-dimensional film that can receive light emission, convert it, and then emit light emission with one or more altered properties. The inorganic coating can be deposited using low-pressure deposition techniques such as atomic layer deposition (ALD). By depositing the inorganic coating using ALD techniques, two or more components, such as an LED and a ceramic phosphor layer, can be joined together.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 417,262, filed November 3, 2016, and U.S. Provisional Patent Application No. 62 / 417,237, filed November 3, 2016, and U.S. Non-Provisional Application No. 15 / 802,273, filed November 2, 2017, the contents of which are incorporated by reference as if fully set forth herein. Background Art

[0003] Light-emitting particles or layers in semiconductor devices deposited or bonded using conventional techniques (e.g., with silicone) can suffer from shorter lifetimes due to degradation of the organic binder. Even in more expensive processes where the light-emitting particles are sintered together at high temperatures to form a ceramic or incorporated into glass, the resulting wavelength-converting plate is typically attached to the semiconductor device using an organic glue that can degrade and discolor under operation at high temperatures and high flux densities of short-wavelength light (e.g., blue or UV). As a result, devices with light-emitting particles deposited or bonded using conventional techniques may need to be replaced within less-than-ideal time periods. Additionally, substrates bonded using conventional techniques in addition to semiconductor devices may also experience these undesirable effects. Consequently, such techniques are insufficient when it comes to bonding light-emitting particles and / or ceramic layers to devices and other substrates. Summary of the Invention

[0004] According to aspects of the present invention, a plurality of optically scattering and / or luminescent particles can be deposited onto a component. An inorganic coating can be deposited onto the plurality of optically scattering particles using a low-pressure deposition technique. The plurality of optically scattering particles can be bonded together to form a three-dimensional film, with the optically scattering and / or luminescent particles bonded to one another via the inorganic coating. The inorganic coating can include multiple layers, one or more of which can be an oxide coating, and the optically scattering and / or luminescent particles can be deposited using techniques such as sedimentation, electrophoretic deposition (EPD), stencil printing, or dispensing. The optically scattering and / or luminescent particles can be phosphor particles, and the component can be a metal, substrate, ceramic, semiconductor, insulator, or a light-emitting device such as a light-emitting diode (LED) or laser. The low-pressure deposition technique can be atomic layer deposition (ALD). The component can be removed or partially removed to allow the three-dimensional film to receive light excitation at one surface and emit light from an opposite surface. The component can also be transparent to light emission and not removed. The component can also be thermally conductive. The assembly can also be opaque to light emission, can be reflective, and can receive optical excitation on the same surface from which light is emitted. The assembly itself can be an excitation source, such as an LED or laser. The coefficient of thermal expansion (CTE) of the inorganic coating can substantially match the CTE of the plurality of optically scattering particles or the CTE of the assembly. The refractive index of the inorganic coating can substantially match the refractive index of the plurality of optically scattering particles or the refractive index of the assembly.

[0005] According to one implementation, the three-dimensional film can receive light of a first wavelength, absorb or partially absorb the light, and emit light of a second wavelength. The emitted light can be the second wavelength or a combination of the first and second wavelengths.

[0006] According to one implementation, multiple three-dimensional films can be arranged adjacent to one another, for example in a linear or matrix array, with separating layers, such as absorbent or reflective materials, located between adjacent three-dimensional films. Multiple three-dimensional films can be placed over individual light-emitting components that can, for example, be activated individually, such that each three-dimensional film is configured to produce independent or isolated light emissions from one another, for example with reduced crosstalk. Alternatively, the light-emitting pixels can be excited from a raster light source, such as a laser or electron beam. This arrangement can be used in systems such as automotive lighting (e.g., adaptive front-lighting systems (AFS)), camera flashes, displays, and the like.

[0007] According to another implementation, the surface of the component and / or the ceramic phosphor layer can be roughened or grooves can be added to the surface. An inorganic coating can be deposited onto the roughened or grooved surface using low pressure deposition techniques, thereby bonding the two components together using the inorganic coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings, which are included to provide a further understanding of the disclosed subject matter, are incorporated into and constitute a part of this specification. The accompanying drawings also illustrate implementations of the disclosed subject matter and, together with the detailed description, serve to explain the principles of implementation of the disclosed subject matter. No attempt is made to show structural details in more detail than is necessary for a basic understanding of the disclosed subject matter and the various ways in which it may be practiced.

[0009] Figure 1a shows a cross-sectional view of light absorbed and emitted by a three-dimensional film with off-axis excitation;

[0010] Figure 1b shows a cross-sectional view of light emitted by a light emitting device and absorbed and converted by a three-dimensional film;

[0011] Figure 1c shows a cross-sectional view of light absorbed and converted by a three-dimensional film;

[0012] Figure 1d shows a cross-sectional view of light absorbed and converted by a three-dimensional film partially surrounded by spacer material;

[0013] Figure 2 A top cross-sectional view showing an arrangement of three-dimensional membranes;

[0014] Figure 3 shows two components joined via an inorganic coating;

[0015] Figure 4 A lighting device is schematically depicted;

[0016] Figure 5a Schematic depiction of luminescent powder particles with a sol-gel first coating;

[0017] Figure 5b An aspect of a particulate luminescent material is schematically depicted;

[0018] Figure 5c An aspect of a particulate luminescent material is schematically depicted;

[0019] Figure 5d An aspect of a particulate luminescent material is schematically depicted;

[0020] Figure 6aShown are the relative light output (LO) of phosphor powders before (SiO2 only) and after ALD coating (Al2O3 on SiO2) as a function of degradation time (in hours); degradation conditions: 60°C / 100% relative humidity; ALD-1: 20 nm Al2O3 on phosphor; ALD-2: 40 nm Al2O3 on phosphor; ALD-3: 20 nm Al2O3 deposited on SiO2 coating; SiO2-1: sol-gel SiO2 coating on phosphor (basis for ALD-3);

[0021] Figure 6b The relative light output (LO) is shown as a function of degradation time given in hours (85°C / 100% RH); ALD-3: 20 nm Al2O3 on SiO2 coating; ALD-4: 20 nm Al2O3 / Ta2O5 nanolaminate deposited on a thin (<10 nm) SiO2 layer; ALD-5: 20 nm Al2O3 / Ta2O5 nanolaminate deposited on SiO2 coating; ALD-6: 20 nm Al2O3 / HfO2 nanolaminate deposited on SiO2 coating; and

[0022] Figure 6c The relative light output (LO) is shown as a function of degradation time in hours (85°C / 100% RH); ALD-3 and ALD-6: samples as described above; ALD-7: 20 nm Al2O3 / HfO2 nanolaminate on a thin (<10 nm) SiO2 layer, nanolaminate design: 4×[1.5 nm Al2O3 / 3.5 nm HfO2]; ALD-8: 10 nm Al2O3 / HfO2 nanolaminate on a thin (<10 nm) SiO2 layer, nanolaminate design: 2×[1.5 nm Al2O3 / 3.5 nm HfO2]. Unless otherwise indicated, sol-gel SiO2 coatings typically have a layer thickness in the range of 150-200 nm. Thin SiO2 layers indicated as having a thickness of <10 nm will typically have an average layer thickness in the range of approximately 1-10 nm. DETAILED DESCRIPTION

[0023] Inorganic coatings can serve as a bonding mechanism and can be used to bond particles together to create a three-dimensional film, which can have some degree of porosity (depending on the packing density of the particles and the degree of gap filling) to bond the particles to a component including a light emitter, to bond a component to another component, or for similar purposes. Inorganic coatings can provide benefits over alternatives such as improved reliability, reduced cost, the generation of transparent or translucent films, matching coefficients of thermal expansion (CTE), refractive index, etc. Particles coated with inorganic materials can experience additional benefits such as higher moisture resistance.

[0024] Depending on the implementation of the disclosed subject matter, optically scattering particles (also encompassed herein and also referred to as luminescent particles) can be bonded together via an inorganic coating applied using a low-pressure deposition technique to create a three-dimensional film. The porous three-dimensional film can be a scattering film and can be standalone or bonded to a component such as a substrate, a light-emitting device, a ceramic phosphor, etc. Excitation, including optical excitation, such as from an LED or laser, can be used to excite all or a portion of the three-dimensional film. Other forms of excitation can include cathodoluminescence from an electron beam source, radioluminescence from an X-ray source, or electroluminescence from an applied electromagnetic field. As a result, converted emission can exit the three-dimensional film from the same side as the excitation entered, or from a different side. The emitted light can be converted emission or a combination of converted emission and optically excited emission, preferably having a desired correlated color temperature (CCT) with a specific color rendering index (Ra). In addition, optical excitation entering the three-dimensional film may experience scattering effects due to interactions with portions of the three-dimensional film.

[0025] Depending on the implementation of the disclosed subject matter, a plurality of optically scattering particles can be joined via an inorganic coating applied to the particles or agglomerates of particles. The particles can include one or more suitable luminescent or optically scattering materials, such as phosphor particles with or without activation from rare earth ions, aluminum nitride, aluminum oxynitride (AlON), barium sulfate, barium titanate, calcium titanate, cubic zirconium oxide, diamond, gadolinium gallium garnet (GGG), lead lanthanum zirconate titanate (PLZT), lead zirconate titanate (PZT), sapphire, silicon aluminum oxynitride (SiAlON), silicon carbide, silicon oxynitride (SiON), strontium titanate, titanium oxide, yttrium aluminum garnet (YAG), zinc selenide, zinc sulfide, and zinc telluride, diamond, silicon carbide (Si C), single crystal aluminum nitride (AlN), gallium nitride (GaN) or aluminum gallium nitride (AlGaN) or any transparent, semi-transparent or scattering ceramic, optical glass, high refractive index glass, sapphire, aluminum oxide, III-V semiconductors (such as gallium phosphide), II-VI semiconductors (such as zinc sulfide, zinc selenide and zinc telluride), Group IV semiconductors and compounds, metal oxides, metal fluorides, oxides of any of the following elements: aluminum, antimony, arsenic, bismuth, calcium, copper, gallium, germanium, lanthanum, lead, niobium, phosphorus, tellurium, thallium, titanium, tungsten, zinc, or zirconium, polycrystalline alumina (transparent Aluminum oxide), aluminum oxynitride (AlON), cubic zirconia (CZ), gadolinium gallium garnet (GGG), gallium phosphide (GaP), lead zirconate titanate (PZT), silicon aluminum oxynitride (SiAlON), silicon carbide (SiC), silicon oxynitride (SiON), strontium titanate, yttrium aluminum garnet (YAG), zinc sulfide (ZnS), spinel, Schott glass LaFN21, LaSFN35, LaF2, LaF3, LaF10, NZK7, NLAF21, LaSFN18, SF59 or LaSF3, Ohar a glass SLAM60 or SLAH51, and may include a nitride luminescent material, a garnet luminescent material, an orthosilicate luminescent material, a SiAlON luminescent material, an aluminate luminescent material, a nitrogen oxide luminescent material, a halide luminescent material, an oxyhalide luminescent material, a sulfide luminescent material and / or an oxysulfide luminescent material, and a luminescent quantum dot including a core material, the core material being selected from cadmium sulfide, cadmium selenide, zinc sulfide, zinc selenide, and may be selected from SrLiAl3N4:Eu(II) (strontium-lithium-aluminum nitride: europium(II) type), or any combination thereof.

[0026] The size of the luminescent or optically scattering particles can depend on the application of the particles in luminescent or similar systems. The size can range from nanometers to 100 μm. 50 Between or between 1μm and 50μm D 50 or 3μm to 30μm D 50 or 5μm to 25μm D 50 or 7μm to 20μm D50 Here, D represents the diameter of the powder particles, and D 50 It refers to the diameter of the cumulative 50% point (or the particle size at which 50% pass), and can also be referred to as the average particle size or median diameter. Phosphor particles with a size of nanometers to 5 μm may be suitable for micro-LED pixel coverage, while particle sizes of 5 to 25 μm are more suitable for higher-power LEDs with a square area of ​​millimeters or larger.

[0027] Depending on the implementation of the disclosed subject matter, a plurality of optically scattering particles may be deposited onto a component that may include one or more suitable materials such as diamond, silicon carbide (SiC), single crystal aluminum nitride (AlN), gallium nitride (GaN) or aluminum gallium nitride (AlGaN), aluminum indium gallium nitride (AlInGaN), optical glass, high refractive index glass, sapphire, diamond, silicon carbide, aluminum oxide, III-V semiconductors (such as gallium phosphide), II-VI semiconductors (such as zinc sulfide, zinc selenide, and zinc telluride), Group IV semiconductors and compounds, metal oxides, metal fluorides, oxides of any of the following elements: aluminum, antimony, arsenic, bismuth, calcium, copper, gallium, germanium, lanthanum, lead, niobium, phosphorus, tellurium, thallium, titanium, tungsten, zinc, or zirconium, polycrystalline aluminum oxide (transparent aluminum oxide), aluminum oxynitride (AlON), cubic zirconium oxide (CZ), gadolinium gallium garnet (GGG), gallium phosphide (GaP), zirconium titanium The component may be any suitable component such as a metal, a substrate, a ceramic, a semiconductor, a light emitting device, or an insulator.

[0028] The particles may be deposited using any suitable technique such as sedimentation, EPD, stencil printing, dispensing in a volatile medium, and the like.

[0029] According to an implementation of the disclosed subject matter, an inorganic coating can be applied to a plurality of optically scattering particles. The coating material can be selected from the same list of materials that can constitute the optically scattering particles or the substrate, or other suitable materials, such as aluminum oxide Al2O3, hafnium oxide HfO2, tantalum oxide Ta2O5, titanium oxide TiO2, zirconium oxide ZrO2, another transparent oxide, etc. The coating can be a single layer or a multilayer of the same or different materials, and can be applied by depositing the material at the surface of the particle from a vapor phase, such as via an atomic layer deposition (ALD) process. Atomic layer deposition can be a suitable method for depositing thin conformal coatings of various inorganic materials on powder particles. For example, the method can be used to fluidize the particles during the ALD coating process to improve the coating quality by preventing particle-particle agglomeration that leads to reduced coating quality.

[0030] The coating can be an oxide, nitride, carbide, arsenide, phosphide, fluoride, sulfide, selenide, telluride, metal, a single element, or tellurite glass. The coating can be any one or a combination of the materials listed for the particle or substrate. The thickness of the inorganic coating can be determined at least in part by the size of the optically scattering particles to which it is bonded. Larger particles require thicker inorganic coatings, and thus, smaller particles may result in thinner inorganic coatings. Depending on the implementation, the inorganic coating can be as thin as a single monolayer of about 3 angstroms to as thick as 1000 angstroms (1000 angstroms is 1 / 10 of a micron), between 1 / 10 of a micron and 1 micron, or between 1 micron and 10 microns, etc.

[0031] The plurality of optical scattering particles 131 may be joined together by an inorganic coating 132 deposited onto the plurality of particles, such as Figures 1a-1d As shown in . Low-pressure or low-partial-pressure deposition (such as CVD, low-pressure CVD, ALD, etc.) can be used to bond the particles, where the coating material has a large diffusion length for deep penetration. Inorganic coatings can create bonds that bond multiple particles together in a free-standing three-dimensional film or above a component such as a substrate or LED. Inorganic coatings can also bond three-dimensional particle films to components such as substrates or LEDs.

[0032] like Figure 1bAs shown in FIG, optical scattering particles 131, which are bonded together via an inorganic coating 132 to create a three-dimensional film 125, may be positioned above an LED 160. The LED 160 may emit light 171a and 171b from the luminescent layer or region 161. Light 171a and 171b pass through the three-dimensional film 125 and exit from the surface opposite the LED 160. As indicated by the distinct arrows, a portion 171a of the light emitted by the LED 160 may be absorbed by the optical scattering particles 131, and a portion 171b of the light may pass through the three-dimensional film 125 without being absorbed by the optical scattering particles. Light 171a absorbed by the luminescent scattering particles 131 may be converted to light of a different wavelength by the luminescent particles or phosphor. Converted light 170c may be emitted from the three-dimensional film 125, combining with light 171b to form the device emission, and the combined light is the desired light emission from the three-dimensional film 125. For example, some of the blue light emitted by the LED may be converted to yellow light, and the combined blue and yellow light may produce light that appears white. An additional phosphor that converts to red can be added to achieve a warmer white (lower CCT) and better color rendering (higher Ra). Alternatively, a UV LED can be used with a blue and yellow phosphor, where the UV is fully absorbed. Furthermore, a third red phosphor can be added to achieve an even warmer white and better color rendering. Amber LED devices can be created by using an amber phosphor with a blue or UV LED to convert the full wavelength to amber emission.

[0033] According to one implementation, a portion of the inorganic coating can be in contact with particle A and particle B such that it both coats the two particles A and B and bonds them together. Alternatively, according to an implementation of the disclosed subject matter, a portion of the three-dimensional film can rest on an assembly comprising a substrate, while another portion of the film is independent. The independent portion of the film can allow light excitation to enter from one side and emission to escape from the other side. For example, an array of pixels can be formed on an independent portion of a substrate with multiple regions removed and a film bridging gap regions. In an illustrative example, as shown in FIG. Figure 1cAs shown in , a portion of the substrate 135 can be removed to create a gap 165. The three-dimensional film 125 can rest on the remaining portion of the substrate 135. Light excitation 185 can be sent toward the three-dimensional film from a light emitting device located on one side of the substrate. The light excitation 185 can be at least partially absorbed by the bonding particles 131 of the three-dimensional film 125, and light emission 180 can escape from the three-dimensional film 125 from the side opposite to the side from which the light excitation 185 enters the three-dimensional film 125. The substrate can be thermally conductive and reflective, such as a metal (e.g., silver or aluminum), or a diffusely reflective material (such as boron nitride). Alternatively, the substrate can be a thermally conductive and absorbing material, such as pyrolytic graphite. Reflective or absorbing substrates with good thermal conductivity can be useful in reducing crosstalk between pixels in a raster scanning laser system with high optical power density. Alternatively, as Figure 1d As depicted in FIG, optically scattering / luminescent particles can be deposited in recesses 137 of substrate 136, wherein substrate 135 and, optionally, at least a portion of the opposite side of substrate 135 can be removed to expose a three-dimensional membrane for transmitting radiation, or in the former case, excitation radiation can be introduced on the same side. In this case, the material of substrate 136 or spacer or separator material 136 attached to substrate 135 can be reflective or absorptive, and the material of substrate 135 or spacer attached to substrate 135 can be reflective or absorptive. Materials 136 and 135 can be the same, with recesses or cavities 137 formed therein; for example, 135 / 136 can be a silicon wafer with recesses 137 etched therein. Alternatively, 136 can be an additional layer of the same or different material on substrate 135. For example, substrate 135 can be boron nitride, with spacer or separator material 136 being a layer of pyrolytic graphite having recesses or cavities 137 formed therein before or after placement on substrate 135.

[0034] Those skilled in the art will appreciate that the optically scattering particles can be provided on the component prior to being bonded via the inorganic coating, as has been provided in the implementations to date, or can be bonded via the inorganic coating and then deposited onto the component. In another embodiment, the particles can be coated first and then bonded together in aggregate. This can be accomplished using a subsequent ALD coating, or if the original coating has a sufficiently low softening temperature, a heat treatment can bond the coated particles together.

[0035] The three-dimensional film can be configured to receive light of a first wavelength. As a result of absorption of this excitation light by one or more optically scattering / luminescent particles, a portion of the received light can be converted into different light having a second wavelength. Depending on the characteristics of the three-dimensional film, the particles, or both, the light emission can include light of the second wavelength or a combination of the first wavelength (e.g., where the original light may not have been absorbed by the particles in the three-dimensional film and passed through or reflected by the film) and the second wavelength. As an example, the three-dimensional film can receive blue light, and the three-dimensional film can convert a portion of the blue light to emit yellow light. The overall light emission through the three-dimensional film can be a combination of blue light and converted yellow light, resulting in effectively white light.

[0036] The coefficient of thermal expansion (CTE) of the coating can be nearly matched to the coefficient of thermal expansion of the optically scattering particles. Alternatively or additionally, the CTE of the coating can be nearly matched to the CTE of the component on which the particles are disposed or the inorganic coating is used to form a bond with a three-dimensional film or other component, as disclosed herein.

[0037] The refractive index of the coating can be nearly matched to that of the optically scattering or luminescent particles. Alternatively or additionally, the refractive index of the coating can be nearly matched to that of the transparent component on which the particles are disposed or bonded to a three-dimensional film or other component using an inorganic coating, as disclosed herein. Alternatively, the refractive index of the coating can be lower than that of the optically scattering or luminescent particles. In this case, the individual particles in the agglomerate retain some of their scattering properties. If the refractive index of the coating matches that of the particles, the scattering of the individual particles disappears, and the scattering properties of the porous three-dimensional film become the dominant scattering mechanism. If multiple particle materials are used, such as garnet phosphor and nitrided silicate phosphor, the refractive index of the coating can be matched to that of the garnet, but the nitrided silicate phosphor can still scatter due to its higher refractive index. For example, an aluminum oxide coating would have a refractive index that nearly matches the refractive index of a garnet phosphor (green or yellow), which is approximately 1.8, while a nitrided silicate phosphor (red) has a refractive index of approximately 2.2.

[0038] Depending on the implementation of the disclosed subject matter, multiple three-dimensional films can be arranged adjacent to each other so that a spacer or separation layer separates each pixel. The separation layer can be, for example, an absorbing layer or a reflective layer, and can be configured for high contrast and high efficiency with low crosstalk. The absorbing layer can include any suitable absorbing material, such as silicon or pyrolytic graphite, and the reflective layer can be any suitable reflective material, such as specular silver, diffusely reflecting boron nitride, loaded silicone with, for example, TiO2, epoxy molding compound, or other white molding compound. As an example, Figure 2 As shown in FIG, a plurality of three-dimensional films 230 may be arranged in a matrix or pixelated pattern 210. A reflective or absorptive layer 220 may separate each film, which may also be Figure 1dSpacers or substrates in cross-section. Reflective or absorptive layers can be used to keep the light emitted by the multiple 3D films separated from each other and visually maintain a pixelated pattern with reduced crosstalk. According to one implementation, multiple light-emitting devices can be placed beneath the multiple 3D films, separated by a separation layer. The multiple devices can be individually addressable and, when activated, emit light toward one or more specific pixel films, allowing for more differentiated control of light emission through the one or more 3D films. As an example, an automotive headlight may contain multiple LEDs placed beneath a pixel-patterned 3D film array, separated from each other by a separation material. The matrix may contain 2, 3, 5, 10, or 100 pixels for a camera flash. For example, the matrix may contain 1,000, 5,000, or 10,000 pixels for an automotive adaptive front-lighting system (AFS), and many times this number for displays. If an application requires millions of pixels, a raster-scanning laser can be used. Raster scanning can be accomplished using microelectromechanical system (MEMS)-based mirrors or using acousto-optic reflectors or deflectors. AFS can be used to flatten the beam of the headlights when the vehicle is heavily loaded, climbing or descending hills or valleys, traversing rough or undulating roads, or maneuvering the beam around curves and turns, thereby creating a projection pattern that creates a hole in the illumination so that drivers of oncoming vehicles and vehicles traveling in the same direction ahead are not dazzled or blinded. U.S. Patent Nos. 6,406,172 and 7,566,155 are hereby incorporated by reference in their entirety. For example, the left column of the three-dimensional film and the corresponding LEDs below them can be turned off by default. Upon receiving a signal that the steering wheel of the car has been turned counterclockwise for more than 30% of its travel, the LEDs below the left column of the three-dimensional film can be switched on and emit light toward the left column of the three-dimensional film. The left column of the three-dimensional film can receive light excitation and emit light from the headlights of the car, so that the emitted light illuminates a scene further to the left than the scene initially illuminated by the headlights before reaching 30% counterclockwise travel of the steering wheel rotation. The advantage of using this arrangement is that the headlights do not need to include moving components to provide rotation-based illumination. AFS systems can be much more complex than the simple system described above and employ cameras, light detection and ranging (LiDAR), image processors, and controllers. Infrared (IR) LEDs or vertical-cavity surface-emitting lasers (VCSELs) can provide supplemental light and information to sensors and detectors. Such image detection and processing systems can predict road topology and sense vehicle and pedestrian traffic to provide optimal lighting for vehicle drivers. Vehicle-to-vehicle, infrastructure, pedestrian, target, or object (V2X) communications can be used to provide location, speed, vehicle type, and size, etc. to adaptive front, rear, and side exterior lighting systems. Components with the desired thermal conductivity, such as diamond, copper, silver, or a combination thereof, can be used as heat sinks.In the examples provided herein, substrates with desirable thermal conductivity can be used as heat sinks in automotive laser headlights or other adaptive lighting systems, as optically scattering / luminescent particles (such as phosphors) may be excited by the laser beam at high power densities, creating the need for a heat sink. Secondary optics such as parabolic reflectors and imaging lenses can be employed. A matrix or pixelated light source can be positioned on a reflective planar surface, with a semi-parabolic reflector covering the reflective planar surface and an imaging or projector lens in the reflected light optical path.

[0039] Depending on the implementation of the disclosed subject matter, the reflective coating may be in contact with or in the optical path of one or more sides of the three-dimensional film. As an example, a reflective and thermally conductive mirror may be disposed between the three-dimensional film and the substrate. Figure 1aAs shown in FIG, light 140 can be emitted toward a three-dimensional film 125, which includes bonded phosphor particles 131. The wavelength of at least a portion of the light can be converted within the three-dimensional film 125, and the light can reach a reflective layer 115, which is disposed on top of a substrate 135. The light can reflect off the reflective layer 115 and exit the three-dimensional film from the same side from which it entered. Similarly, an optical filter, such as a wavelength-selective filter, can be in contact with or in the optical path of one or more sides of the three-dimensional film. As an example, an optical filter (not shown) on the emission exit surface or emission side of the three-dimensional film 125 can be more reflective for blue light and more transmissive for longer wavelengths of light, such as green, yellow, and red light. Using this filter to filter light can improve wavelength conversion efficiency, depending on the desired outcome. U.S. Patent No. 9,543,478 is hereby incorporated by reference in its entirety. The reflective coating and / or filter can be a distributed Bragg reflector (DBR) or a dichroic mirror made of alternating layers of materials with different refractive indices, such as dielectrics. The reflective coating and / or filter can also include a metal layer, such as one made at least partially of silver (Ag), and can include additional metal oxide or dielectric layers, such as TiW or TiWNx. Bandpass filters, such as neodymium (Nd) coatings, can be used. Examples of DBRs or dichroic filters include alternating layers of Nb2O5, SiO2, TiO2, and any other suitable material. The thickness can be at least 10 nm in some embodiments, no more than 5 microns in some embodiments, at least 1 micron in some embodiments, and no more than 2 microns in some embodiments. The total number of layers can be at least 2 in some embodiments, no more than 50 in some embodiments, at least 10 in some embodiments, and no more than 30 in some embodiments. Each layer can be the same thickness, or layers of varying thicknesses can be used. The filter can be deposited using any suitable technique, including sputtering, plasma vapor deposition, chemical vapor deposition, and evaporation. The filter can be between the excitation source and the 3D converter film, on the emission side of the 3D converter film (if these surfaces are different), or on one or more sides of the 3D converter film. For very high brightness (low etendue) applications, large top and / or bottom areas of the 3D converter film can be pumped along with other unpumped surfaces with reflectors and emission extracted from one or more edges.

[0040] Depending on the implementation of the disclosed subject matter, an inorganic coating as described herein can be used to bond a component to another component, where the component can be a substrate, an LED, a ceramic phosphor, a ceramic, a metal, an insulator, a semiconductor, or other light-emitting device, among others. The surface of one or both of the components being bonded can be treated to allow the inorganic coating precursor to more easily access the bonding area of ​​the components. The treatment can be roughening of the surface of one or both components to which the inorganic coating is to be bonded. Alternatively or additionally, grooves can be added to the surface of one or both components to enable the inorganic coating to penetrate the surface. As an example, a ceramic phosphor can be bonded to a light emitter, another ceramic phosphor, or a substrate. The coefficient of thermal expansion (CTE) and / or refractive index of the ceramic phosphor can be nearly matched to the CTE and / or refractive index of the component being bonded to the ceramic phosphor. Surface roughness and / or grooves can be formed on one or more of the surfaces to be bonded to enable the ALD coating to penetrate.

[0041] like Figure 3 , a substrate 310 can be bonded to a ceramic phosphor plate 330 via an inorganic coating 320. The two surfaces to be bonded together can be processed so that a surface 315 corresponding to the substrate 310 and a surface 335 corresponding to the ceramic phosphor plate 330 can be roughened. The roughened surfaces can allow the inorganic coating 320 to penetrate the entire corresponding bonding surface during the ALD process. After the treatment process, the inorganic coating 320 can be applied to both surfaces 315 and 335 via a low-pressure deposition technique such as an ALD process. The inorganic coating then bonds the two surfaces 315 and 335 together, resulting in a structure in which the substrate 310 is bonded to the ceramic phosphor plate 330 via the inorganic coating.

[0042] According to implementations of the disclosed subject matter, the ceramic phosphor plate may include Y3Al5O 12 :Ce 3+ The ceramic phosphor plate can be a rare earth metal activated oxynitride aluminum silicate emitting amber to red, with the general formula (Ca 1-x-y- z Sr x Ba y Mg z ) 1-n (Al 1-a+b B a )Si 1-b N 3-b O b :RE n3, where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1, 0 ≤ a ≤ 1, 0 ≤ b ≤ 1 and 0.002 ≤ n ≤ 0.2, and RE can be selected from europium (II) and cerium (III). The phosphor in the ceramic phosphor plate can also be an oxido-nitrido-silicate with the general formula EA 2-z Si 5-a B a N 8-a O a : Ln z , where 0 ≤ z ≤ 1 and 0 < a < 5, including at least one element EA selected from the group consisting of Mg, Ca, Sr, Ba and Zn and at least one element B selected from the group consisting of Al, Ga and In, and activated by a lanthanide element (Ln) selected from the group consisting of cerium, europium, terbium, praseodymium and mixtures thereof.

[0043] The ceramic phosphor plate can also be an aluminum garnet phosphor having the general formula (Lu 1-x-y-a-b Y x Gd y )3(Al 1-z Ga z )5O 12 : Ce a Pr b , where 0 < x < 1, 0 < y < 1, 0 ≤ z ≤ 0.1, 0 < a ≤ 0.2 and 0 ≤ b ≤ 0.1, such as Lu3Al5O 12 : Ce 3+ and Y3Al5O 12 : Ce 3+ , which emits light in the yellow-green range; and (Sr 1-x-y Ba x Ca[[ID=I44]] y ) 2-z Si 5-a Al a N 8-a O a : Eu z 2+ , where 0 ≤ a < 5, 0 ≤ x ≤ 1, 0 ≤ y ≤ 1 and 0 ≤ z ≤ 1, such as Sr2Si5N8: Eu 2+ , which emits light in the red range. Other phosphors emitting green, yellow and red can also be suitable, including (Sr 1-a-b Ca b Ba c )Si x N y O z : Eu a 2+(a=0.002-0.2, b=0.0-0.25, c=0.0-0.25, x=1.5-2.5, y=1.5-2.5, z=1.5-2.5), including SrSi2N2O2:Eu 2+ ;(Sr 1-u-v-x Mg u Ca v Ba x )(Ga 2-y-z Al y In z S4): Eu 2+ , including for example SrGa2S4:Eu 2+ ; Sr 1-x Ba x SiO4:Eu 2+ ; and (Ca 1-x Sr x )S:Eu 2+ , where 0≤x≤1, including CaS:Eu 2+ and SrS:Eu 2+ Other suitable phosphors include CaAlSiN3:Eu 2+ , (Sr, Ca)AlSiN3:Eu 2+ and (Sr, Ca, Mg, Ba, Zn) (Al, B, In, Ga) (Si, Ge) N3: Eu 2+ .

[0044] Ceramic phosphor plates may also have the general formula (Sr 1-a-b Ca b Ba c Mg d Zn e )Si x N y O z :Eu a 2+, where 0.002≤a≤0.2, 0.0≤b≤0.25, 0.0≤c≤0.25, 0.0≤d≤0.25, 0.0≤e≤0.25, 1.5≤x≤2.5, 1.5≤y≤2.5, and 1.5≤z≤2.5. The ceramic phosphor plate may also have the general formula MmAaBbOoNn:Zz, where element M is one or more divalent elements, element A is one or more trivalent elements, element B is one or more tetravalent elements, O is oxygen that is optional and may not be present in the phosphor plate, N is nitrogen, element Z is an activator, and n=2 / 3m+a+4 / 3b-2 / 3o, where m, a, and b may all be 1, o may be 0, and n may be 3. M is one or more elements selected from Mg (magnesium), Ca (calcium), Sr (strontium), Ba (barium), and Zn (zinc). Element A is one or more elements selected from B (boron), Al (aluminum), In (indium), and Ga (gallium). Element B is Si (silicon) and / or Ge (germanium). Element Z is one or more elements selected from rare earth metals or transition metals. Element Z is at least one or more elements selected from Eu (europium), Mg (manganese), Sm (samarium), and Ce (cerium). Element A may be Al (aluminum), element B may be Si (silicon), and element Z may be Eu (europium).

[0045] Ceramic phosphor plates can also be Eu 2+ Activated Sr-SiON, which has the formula (Sr 1-a-b Ca b Ba c )Si x N y O x :Eu a , where a=0.002-0.2, b=0.0-0.25, c=0.0-0.25, x=1.5-2.5, y=1.5-2.5.

[0046] The ceramic phosphor plate may also be a chemically altered Ce:YAG (yttrium aluminum garnet) phosphor produced by doping the Ce:YAG phosphor with trivalent ions of praseodymium (Pr). The ceramic phosphor plate may include a primary fluorescent material and a supplementary fluorescent material. The primary fluorescent material may be a Ce:YAG phosphor, and the supplementary fluorescent material may be a europium (Eu) activated strontium sulfide (SrS) phosphor ("Eu:SrS"). The primary fluorescent material may also be a Ce:YAG phosphor or any other suitable yellow emitting phosphor, and the supplementary fluorescent material may also be a mixed ternary crystalline material of calcium sulfide (CaS) and strontium sulfide (SrS) activated with europium (Eu). x Sr 1_x )S:Eu 2+). The main fluorescent material may also be Ce:YAG phosphor or any other suitable yellow emitting phosphor, and the supplementary fluorescent material may also be nitrided silicate doped with europium. The nitrided silicate supplementary fluorescent material may have the chemical formula (Sr 1-x-y-z Ba x Ca y )2Si5N8:Eu z 2+ , where 0≤x, y≤0.5 and 0≤z≤0.1.

[0047] The ceramic phosphor plates may also have mixtures of any of the phosphors described above.More information may be found in U.S. Patent Nos. 7,462,502, 7,419,839, 7,544,309, 7,361,938, 7,061,024, 7,038,370, 6,717,353, and 6,680,569, and U.S. Patent Application Publication No. 20060255710, which are commonly assigned and incorporated by reference in their entireties.

[0048] Implementations of the disclosed subject matter may be applied to any suitable lighting device or system, such as automotive lighting assemblies including headlights, taillights, etc., flash lighting, LEDs, programmable lighting systems, etc.

[0049] Depending on the implementation of the disclosed subject matter, an ALD process can be used to coat particles and can also be used to form a coating configured to bond multiple particles together. The following disclosure is associated with an ALD process and hybrid processes (such as a sol-gel process preceding the ALD process), which can be incorporated through the implementations disclosed herein. Although the following disclosure may generally relate to coating individual particles, it will be understood by those skilled in the art that some of the processes described in WO2016041838A1 and herein can be utilized when generating three-dimensional films bonded via inorganic coatings.

[0050] A method for providing luminescent particles having a hybrid coating is provided and comprises: (i) providing a first coating layer ("first coating layer" or "sol-gel coating" or "sol-gel coating layer") onto the luminescent particles by application of a sol-gel coating process, thereby providing coated luminescent particles; and (ii) providing a second coating layer ("second coating layer" or "ALD coating" or "ALD coating layer") onto the coated luminescent particles by application of an atomic layer deposition process, in particular a method wherein the second coating layer comprises a multilayer having layers with different chemical compositions, and wherein in the atomic layer deposition process the metal oxide precursor is in particular selected from the group of metal oxide precursors of a metal selected from aluminum, hafnium, tantalum, zirconium, titanium and silicon. The metal oxide precursor may include trimethylaluminum, tetrakis(dimethylamino)hafnium, tetrakis(diethylamino)hafnium, tetrakis(methyl-ethylamino)hafnium, tantalum chloride, penta(dimethylamino)tantalum, (tert-butylamino)tris(methylethylamino)tantalum, zirconium tetrachloride, tetrakis(dimethylamino)zirconium, tetramethoxytitanium, tetraethoxytitanium, silicon tetrachloride, (3-aminopropyl)triethoxysilane, tetraethoxysilane, and the oxygen source may be selected from water and ozone (O3). The layers in the multilayer may include aluminum oxide, hafnium oxide, zirconium oxide, titanium oxide and silicon dioxide, preferably tantalum pentoxide and aluminum oxide. Figure 5a 、 5b 5 c, the luminescent core 102 includes a non-oxide, and an intermediate oxide layer exists between the luminescent core 102 and the coating layer 135. The sol-gel coating comprises providing a stirred mixture of alcohol, ammonia, and water, adding the metallic luminescent particles 100 and a metal alkoxide precursor selected from titanium alkoxide, silicon alkoxide, and aluminum alkoxide to the mixture to form a coating layer (A) on the luminescent particles 100, and withdrawing the luminescent particles from the mixture and heat-treating the luminescent particles.

[0051] The precursor used in the sol-gel coating can be a silicon alkoxide precursor selected from the formula R4-Si(-R1)(-R3)(-R2)(I). The silicon alkoxide precursor is preferably selected from trimethoxysilane, triethoxysilane, tetraethoxysilane, trimethoxy(methyl)silane, and triethoxy(methyl)silane. R1-R3 = a hydrolyzable alkoxy moiety; and R4 = a 1-6C linear alkyl moiety, a hydrolyzable alkoxy moiety, and a phenyl moiety.

[0052] Depending on the implementation, the luminescent / optically scattering particles may include a luminescent core, a first coating layer ("sol-gel coating layer"), and a second coating layer ("ALD coating layer"). The first coating layer may have a first coating layer thickness (d1) in the range of 5-500 nm, in particular 10-500 nm, even more particularly 5-500 nm, in particular 10-500 nm, even more particularly 20-500 nm, in particular 50-300 nm (such as at least 100 nm), and the second coating layer may have a second coating layer thickness (d2) in the range of 5-250 nm (such as in particular 5-200 nm), even more particularly, wherein the second coating layer includes a multilayer having layers with different chemical compositions, and wherein the multilayer includes one or more layers containing oxides of one or more of Al, Hf, Ta, Zr, Ti, and Si.

[0053] By means of such a luminescent material, i.e. such a luminescent material comprising these (hybrid-coated) particles, a relatively stable luminescent material is provided which has a quantum efficiency close to or the same as that of the original (uncoated) luminescent material and has a stability towards water and / or (humid) air which is very high and better than that of uncoated or non-hybrid-coated luminescent particles.

[0054] The first coating layer may optionally include multiple layers. However, the multiple layers of the first coating layer may be sol-gel layers. Therefore, the first layer is also referred to herein as a sol-gel layer (thus optionally including sol-gel multilayers). The first coating layer particularly includes silicon oxide (particularly SiO2). Examples of multilayers may include SiO2-Al2O3 (sol-gel) multilayers, such as a stack of three or more (sol-gel) layers in which SiO2 and Al2O3 alternate.

[0055] Likewise, the second coating layer may optionally include multiple layers. However, the multiple layers of the second coating layer may all be ALD layers. Therefore, the second layer is indicated as an ALD layer (thus optionally including multiple ALD layers).

[0056] In particular, the second coating layer does comprise multiple layers, see also below. Furthermore, in particular, the second coating layer is provided on the first coating layer without an intermediate layer. Optionally, further coating layers may be provided on the second coating layer. The second coating layer in particular comprises at least one or more coating layers of aluminum oxide (in particular, Al2O3). In particular, both the first coating layer and the second coating layer independently comprise a metal oxide, but optionally a hydroxide may also be included in one or more of these layers. Furthermore, the first coating layer and the second coating layer may independently comprise mixed oxide layers. Furthermore, as is known in the art, the coating layers do not necessarily need to be completely stoichiometric oxides.

[0057] Typically, the thickness of the first coating layer will be greater (such as at least 1.2 times, such as at least 1.5 times, such as at least 2 times, or even at least 4 times or at least 5 times) than the thickness of the second coating layer. In a specific embodiment, the method of the present invention comprises (i) applying the sol-gel coating process to provide a first coating layer onto the luminescent particle, the first coating layer having a first coating layer thickness (d1) in the range of, in particular, 20-500 nm (such as at least 50 nm), even more in particular 50-300 nm (such as at least 100 nm), thereby providing the coated luminescent particle; and (ii) applying the atomic layer deposition process to provide a second coating layer onto the coated luminescent particle, the second coating layer having a second coating layer thickness (d2) in the range of, in particular, 5-250 nm (such as 5-200 nm), in particular at least 10 nm, even more in particular 10-100 nm (such as 15-75 nm), more in particular 15-50 nm. Thus, as indicated above, the luminescent particle, in one embodiment, comprises a luminescent core, a first coating layer, and a second coating layer. The first coating layer has a first coating layer thickness (d1) in the range of, in particular, 5-500 nm, in particular, 10-500 nm, even more particularly, 20-500 nm, more particularly, 50-300 nm (such as at least 100 nm), and the second coating layer has a second coating layer thickness (d2) in the range of, in particular, 5-250 nm, even more particularly, 15-50 nm (such as in the range of 15-35 nm). It appears that thicker first layers provide better results than thinner layers. Thus, in particular, the first coating layer has a first coating layer thickness of at least 50 nm (such as at least about 100 nm).

[0058] In principle, the luminescent particles of interest can include any type of luminescent particle. However, of particular interest are those types of luminescent particles that may be less stable in air, water, or a humid environment, such as, for example, (oxy)sulfides, (oxy)nitrides, and the like. Therefore, in one embodiment, the luminescent particles include one or more of a nitride luminescent material, an oxynitride luminescent material, a halide luminescent material, an oxyhalide luminescent material, a sulfide luminescent material, and an oxysulfide luminescent material. Additionally or alternatively, the luminescent particles may include a selenide luminescent material. Therefore, the term "luminescent particle" may also refer to a combination of particles of different types of luminescent materials.

[0059] In a specific embodiment, the luminescent particles can be selected from the following luminescent material systems: MLiAl3N4:Eu (M=Sr, Ba, Ca, Mg), M2SiO4:Eu (M=Ba, Sr, Ca), MSe 1-x S x: Eu (M=Sr, Ca, Mg), MSr2S4: Eu (M=Sr, Ca), M2SiF6: Mn (M=Na, K, Rb), MSiAlN3: Eu (M=Ca, Sr), M8 Mg(SiO4)4Cl2:Eu(M=Ca,Sr),M3MgSi2O8:Eu(M=Sr,Ba,Ca),MSi2O2N2:Eu(M=Ba,Sr,Ca),M2Si 5-x Al x O x N 8-x : Eu (M = Sr, Ca, Ba). However, other systems may also be of interest for protection via mixed coatings. Furthermore, combinations of particles of two or more different luminescent materials may be used, such as, for example, a green or yellow luminescent material combined with a red luminescent material.

[0060] As is known in the art, terms such as "M=Sr, Ba, Ca, Mg" indicate that M includes one or more of Sr, Ba, Ca and Mg. For example, referring to MSiAlN3:Eu (M=Ca, Sr), this may refer to CaSiAlN3:Eu, or SrSiAlN3:Eu, or CaSiAlN3:Eu. 0.8 Sr 0.2 SiAlN3:Eu, etc. In addition, the formula "MLiAl3N4:Eu (M = Sr, Ba, Ca, Mg)" is equivalent to the formula (Sr, Ba, Ca, Mg)LiAl3N4:Eu. The same applies to other formulas of inorganic phosphors indicated herein.

[0061] In another specific embodiment, the luminescent particles can be selected from the following group of luminescent material systems: 1-x-y- z Z z A a B b C c D d E e N 4-n O n :ES x ,RE y, where M is selected from the group consisting of Ca (calcium), Sr (strontium), and Ba (barium); Z is selected from the group consisting of monovalent Na (sodium), K (potassium), and Rb (rubidium); A is selected from the group consisting of divalent Mg (magnesium), Mn (manganese), Zn (zinc), and Cd (cadmium) (in particular, A is selected from the group consisting of divalent Mg (magnesium), Mn (manganese), and Zn (zinc), and even more particularly from the group consisting of divalent Mg (magnesium) and Mn (manganese)); B is selected from the group consisting of trivalent B (boron), Al (aluminum), and Ga (gallium); C is selected from the group consisting of tetravalent Si (silicon), Ge (germanium), Ti (titanium), and Hf (hafnium); D is selected from the group consisting of monovalent Li (lithium) and Cu (copper); E is selected from the group consisting of P (elemental phosphorus), V (vanadium), Nb (niobium), and Ta (tantalum); ES is selected from the group consisting of divalent Eu (europium), Sm (samarium), and ytterbium, particularly from the group consisting of divalent Eu and Sm; RE is selected from the group consisting of trivalent Ce (cerium), Pr (praseodymium), Nd (neodymium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), and Tm (thulium); where 0 ≤ x ≤ 0.2; 0 ≤ y ≤ 0.2; 0 < x + y ≤ 0.4; 0 ≤ z < 1; 0 ≤ n ≤ 0.5; 0 ≤ a ≤ 4 (such as 2 ≤ a ≤ 3); 0 ≤ b ≤ 4; 0 ≤ c ≤ 4; 0 ≤ d ≤ 4; 0 ≤ e ≤ 4; a + b + c + d + e = 4; and 2a + 3b + 4c + d + 5e = 10 – y – n + z. In particular, z ≤ 0.9, such as z ≤ 0.5. Additionally, in particular, x + y + z ≤ 0.2.

[0062] In particular, the equations a + b + c + d + e = 4 and 2a + 3b + 4c + d + 5e = 10 – y – n + z respectively determine the Z, A, B, C, D, and E cations and the O and N anions in the lattice, and thus (also) define the charge neutrality of the system. For example, the charge compensation is covered by the equation 2a + 3b + 4c + d + 5e = 10 – y – n + z. It compensates for the charge compensation, for example, by reducing the O content, or by substituting C cations with B cations, or by substituting B cations with A cations, etc. For example: x = 0.01, y = 0.02, n = 0, a = 3; then 6 + 3b + 4c = 10 - 0.02; where a + b + c = 4: b = 0.02, c = 0.98.

[0063] As will be clear to those skilled in the art, a, b, c, d, e, n, x, y, and z are always equal to or greater than zero. When a is defined in combination with the equations a + b + c + d + e = 4 and 2a + 3b + 4c + d + 5e = 10-yn + z, then, in principle, b, c, d, and e no longer need to be defined. However, for the sake of completeness, 0 ≤ b ≤ 4; 0 ≤ c ≤ 4; 0 ≤ d ≤ 4; and 0 ≤ e ≤ 4 are also defined here.

[0064] Consider, for example, the system SrMg2Ga2N4:Eu. Here, a = 2, b = 2, c = d = e = y = z = n = 0. In such a system, 2 + 2 + 0 + 0 + 0 = 4 and 2 * 2 + 3 * 2 + 0 + 0 + 0 = 10-0-0 +0 = 10. Therefore, both equations hold. Assuming 0.5 O is introduced, for example, when 0.5 Ga-N is replaced by 0.5 Mg-O (which is an electrically neutral substitute), a system with 0.5 O can be obtained. This will result in SrMg 2.5 Ga 1.5 N 3.5 O 0.5 : Eu. Here, in the system 2.5 + 1.5 + 0 + 0 + 0 = 4 and 2 * 2.5 + 3 * 1.5 + 0 + 0 + 0 = 10 - 0 - 0.5 + 0 = 9.5. Therefore, both equations are satisfied here.

[0065] As indicated above, in advantageous embodiments, d>0 and / or z>0, in particular at least d>0. In particular, the phosphor comprises at least lithium.

[0066] In yet another embodiment, 2≤a≤3, and in particular, also d = 0, e = 0 and z = 0. In such a case, the phosphor is characterized in particular by a + b + c = 4 and 2a + 3b + 4c = 10-yn.

[0067] In another embodiment that can be combined with the previous embodiment, e = 0. In yet another embodiment that can be combined with the previous embodiment, M is Ca and / or Sr.

[0068] Thus, in a specific embodiment, the phosphor has the formula M (Ca and / or Sr) 1-x-y Mg a Al b Si c N 4-n O n :ES x, RE y (I), where ES = selected from the group consisting of divalent Eu (europium), Sm (samarium), or Yb (ytterbium); RE = selected from the group consisting of trivalent Ce (cerium), Pr (praseodymium), Nd (neodymium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), and Tm (thulium), where y / x < 0.1, particularly < 0.01, and n ≤ 0.1, particularly < 0.01, even more particularly < 0.001, and yet even more particularly < 0.0001. Thus, in this embodiment, phosphors containing samarium and / or europium are mainly described. For example, when divalent Eu is present, where x = 0.05, and for example, y1 of Pr can be 0.001, and y2 of Tb can be 0.001, resulting in y = y1 + y2 = 0.002. In this case, y / x = 0.04. Even more particularly, y = 0. However, as indicated elsewhere, when Eu and Ce are applied, the ratio y / x can be greater than 0.1.

[0069] The condition 0 < x + y ≤ 0.4 indicates that M can be replaced with a total of up to 40% of ES and / or RE. The condition "0 < x + y ≤ 0.4" combined with x and y between 0 and 0.2 indicates the presence of at least one of ES and RE. It is not necessary for both types to be present. As indicated above, both ES and RE can each individually refer to one or more subspecies, such as ES referring to one or more of Sm and Eu, and RE referring to one or more of Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Tm.

[0070] Particularly, when europium is applied as a divalent luminescent substance or dopant (i.e., Eu 2+ ), the molar ratio between samarium and europium (Sm / Eu) is < 0.1, particularly < 0.01, particularly < 0.001. The same applies when europium is applied in combination with ytterbium. When europium is applied as a divalent luminescent substance or dopant, the molar ratio between ytterbium and europium (Yb / Eu) is < 0.1, particularly < 0.01, particularly < 0.001. If all three are applied together, the same molar ratio can be applied, i.e., ((Sm + Yb) / Eu) is < 0.1, particularly < 0.01, particularly < 0.001.

[0071] In particular, x is in the range of 0.001-0.2 (i.e., 0.001 ≤ x ≤ 0.2), such as 0.002-0.2, such as 0.005-0.1, and particularly 0.005-0.08. In particular, in the case of divalent europium in the systems described herein, the molar percentage may be in the range of 0.1-5% (0.001 ≤ x ≤ 0.05), such as 0.2-5%, such as 0.5-2%. For other luminescent ions, in embodiments, x may (but is not necessarily) be equal to or greater than 1% (x is equal to or greater than 0.01).

[0072] In a specific embodiment, the phosphor is selected from (Sr, Ca)Mg3Si4:Eu, (Sr, Ca)Mg2Al2N4:Eu, (Sr, Ca)LiAl3N4:Eu and (Sr, Ca)Li d Mg a Al b N4: The group consisting of Eu, wherein a, b, and d are as defined above.

[0073] As also indicated herein, the notation "(Sr, Ca)" and similar notations for other elements indicate that the M sites are occupied by Sr and / or Ca cations (or other elements, respectively).

[0074] In another embodiment, the phosphor is selected from Ba .95 Sr .05 Mg2Ga2N4: Eu, BaMg2Ga2N4: Eu, SrMg3SiN4: Eu, SrMg2Al2N4: Eu, SrMg2Ga2N4: Eu, BaMg3SiN4: Eu, CaLiAl3N4: Eu, SrLiAl3N4: Eu, CaLi 0.5 MgAl 2.5 N4: Eu and SrLi 0.5 MgAl 2.5 N4: The group consisting of Eu. Other (non-limiting) examples of such phosphors are, for example (Sr 0.8 Ca 0.2 ) 0.995 LiAl 2.91 Mg 0.09 N 3.91 O 0.09 :Eu 0.005 ;(Sr 0.9 Ca 0.1 ) 0.905 Na 0.09 LiAl3N 3.91 O 0.09 :Eu 0.005 ;(Sr 0.8 Ca 0.03 Ba0.17 ) 0.989 LiAl 2.99 Mg 0.01 N4: Ce 0.01 , Eu 0.001 ;Ca 0.995 LiAl 2.995 Mg 0.005 N 3.99 5O 0.005 :Yb 0.005 (YB(II));Na 0.995 MgAl3N4:Eu 0.005 ;Na 0.895 Ca 0.1 Mg 0.9 Li 0.1 Al3N4:Eu 0.005 ; Sr 0.99 LiMgAlSiN4:Eu 0.01 ;Ca 0.995 LiAl 2.955 Mg 0.045 N 3.96 O 0.04 :Ce 0.005 ;(Sr 0.9 Ca 0.1 ) 0.998 Al 1.99 Mg 2.01 N 3.99 O 0.01 :Eu 0.002 ;(Sr 0.9 Ba 0.1 ) 0.998 Al 1.99 Mg 2.01 N 3.99 O 0.01 :Eu 0.002 .

[0075] In another embodiment, the phosphor is selected from the group consisting of (Sr, Ca)Mg3SiN4:Eu and (Sr, Ca)Mg2Al2N4:Eu. In yet another embodiment, the phosphor is selected from the group consisting of Ba 0.95 Sr 0.05 The group consisting of Mg2Ga2N4:Eu, BaMg2Ga2N4:Eu, SrMg3SiN4:Eu, SrMg2Al2N4:Eu, SrMg2Ga2N4:Eu, and BaMg3SiN4:Eu. In particular, these phosphors, and even more particularly (Sr,Ca)Mg3SiN4:Eu and (Sr,Ca)Mg2Al2N4:Eu, can be phosphors with good luminescent properties, especially in terms of spectral position and luminescent distribution.

[0076] Of particular interest are phosphors wherein the phosphor satisfies 0 ≤ x ≤ 0.2, y / x < 0.1, M comprises at least Sr, z ≤ 0.1, a ≤ 0.4, 2.5 ≤ b ≤ 3.5, B comprises at least Al, c ≤ 0.4, 0.5 ≤ d ≤ 1.5, D comprises at least Li, e ≤ 0.4, n ≤ 0.1, and wherein ES comprises at least Eu. In particular, y + z ≤ 0.1. Furthermore, in particular, x + y + z ≤ 0.2. Furthermore, in particular, a is approximately 0 or 0. Furthermore, in particular, b is approximately 3. Furthermore, in particular, c is approximately 0 or 0. Furthermore, in particular, d is approximately 1. Furthermore, in particular, e is approximately 0 or 0. Furthermore, in particular, n is approximately 0 or 0. Furthermore, in particular, y is approximately 0 or 0. Particularly good systems in terms of quantum efficiency and hydrolytic stability are those with z + d > 0, i.e. one or more of Na, K, Rb, Li and Cu(I) (especially at least Li) are available, such as, for example, (Sr,Ca)LiAl3N4:Eu and (Sr,Ca)Li d Mg a Al b N4:Eu, wherein a, b, d are as defined above. In another embodiment, the phosphor is selected from CaLiAl3N4:Eu, SrLiAl3N4:Eu, CaLi 0.5 MgAl 2.5 N4: Eu and SrLi 0.5 MgAl 2.5 Another phosphor of particular interest is (Sr, Ca, Ba)(Li, Cu)(Al, B, Ga)3N4:Eu, which includes at least Sr as M ion, at least Al as B ion, and at least Li as D ion.

[0077] Therefore, in a specific embodiment, the luminescent particles include a material selected from SrLiAl3N4:Eu 2+ The term "class" herein refers specifically to a group of materials having the same crystalline structure(s). In addition, the term "class" may also include partial substitution of cations and / or anions. For example, in some of the above classes, Al-O may be partially replaced by Si-N (or vice versa). The above provides SrLiAl3N4:Eu 2+ However, other luminescent materials may also be possible.

[0078] Such luminescent particles can have a number-average particle size selected from the range of 0.1-50 μm, such as within the range of 0.5-40 μm, such as in particular within the range of 0.5-20 μm. Thus, the luminescent core can have a size, such as a maximum of approximately 500 μm, such as a maximum of 100 μm, for example, a maximum of approximately 50 μm. In particular, with larger particle sizes, it is essentially only possible to coat individual particles, resulting in a luminescent core size on the order of 50 μm or less. Therefore, the present invention is directed to coating particles. When nanoparticles or quantum dots are used as the basis for the particulate luminescent material, the size of the luminescent core can be substantially smaller. In this case, the core can be less than approximately 1 μm or substantially smaller (see also QD sizes below). Alternatively or additionally, the luminescent particles comprise luminescent quantum dots. In embodiments, the terms "quantum dots" or "luminescent quantum dots" may also refer to a combination of different types of quantum dots, i.e., quantum dots with different spectral properties. QDs are also referred to herein as "wavelength converter nanoparticles" or "luminescent nanoparticles." The term "quantum dot" refers in particular to quantum dots that emit light in one or more of the UV, visible and IR (upon excitation with suitable radiation, such as UV radiation). The quantum dots or luminescent nanoparticles indicated herein as wavelength converter nanoparticles may, for example, comprise II-VI compound semiconductor quantum dots (core-shell quantum dots, wherein the core is selected from the group consisting of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, Hg ZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe. In another embodiment, the luminescent nanoparticles may be, for example, III-V compound semiconductor quantum dots (core-shell quantum dots, wherein the core is selected from the group consisting of GaN, GaP, GaAs, AlN, AlP, AlAs, InN, InP, InGaP, InAs, GaNPs, GaNAs, GaPAs, AlNPs, AlNAs, AlPAs, InNPs, InNAs, InPAs, GaAlNPs, GaAlNAs, GaAlPAs, GaInNPs, GaInNAs, GaInPAs, InAlNPs, InAlNAs and InAlPAs.In yet another embodiment, the luminescent nanoparticles may be, for example, chalcopyrite-type semiconductor quantum dots of Group I-III-VI2 (core-shell quantum dots, wherein the core is selected from the group consisting of the following substances): CuInS2, CuInSe2, CuGaS2, CuGaSe2, AgInS2, AgInSe2, AgGaS2, and AgGaSe2. In yet another embodiment, the luminescent nanoparticles may be, for example, IV-VI2 semiconductor quantum dots (core-shell quantum dots, wherein the core is selected from the group consisting of IV-VI2 semiconductor quantum dots), such as (core-shell quantum dots, wherein the core is selected from the group consisting of the following substances): LiAsSe2, NaAsSe2, and KAsSe2. In yet another embodiment, the luminescent nanoparticles may be, for example, core-shell quantum dots, wherein the core is selected from the group consisting of IV-VI compound semiconductor nanocrystals (such as SbTe). In a specific embodiment, the luminescent nanoparticles are selected from the group consisting of the following substances (core-shell quantum dots, wherein the core is selected from the group consisting of the following substances): InP, CuInS2, CuInSe2, CdTe, CdSe, CdSeTe, AgInS2 and AgInSe2. In another embodiment, the luminescent nanoparticles can be, for example, one of the following substances (core-shell quantum dots, wherein the core is selected from the group consisting of the following substances): II-VI, III-V, I-III-V and IV-VI compound semiconductor nanocrystals selected from the materials described above with internal dopants (such as ZnSe:Mn, ZnS:Mn). The dopant element can be selected from Mn, Ag, Zn, Eu, S, P, Cu, Ce, Tb, Au, Pb, Tb, Sb, Sn and Tl. In this article, the luminescent material based on the luminescent nanoparticles can also include different types of QDs, such as CdSe and ZnSe:Mn.

[0079] The use of II-VI quantum dots appears to be particularly advantageous. Thus, in one embodiment, the semiconductor-based light-emitting quantum dots comprise II-VI quantum dots, in particular selected from the group consisting of the following substances (core-shell quantum dots, wherein the core is selected from the group consisting of the following substances): CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS , CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe, even more particularly, selected from the group consisting of CdS, CdSe, CdSe / CdS and CdSe / CdS / ZnS.

[0080] In one embodiment, the wavelength converter nanoparticles have an average particle size in the range of about 1 to about 1000 nanometers (nm), and preferably, in the range of about 1 to about 100 nm. In one embodiment, the nanoparticles have an average particle size in the range of about 1 to about 20 nm. In one embodiment, the nanoparticles have an average particle size in the range of about 1 to about 10 nm. The luminescent nanoparticles (uncoated) may have a size in the range of about 2-50 nm, such as 2-20 nm, particularly 2-10 nm, and even more particularly 2-5 nm; in particular, at least 90% of the nanoparticles have a size within the indicated ranges (i.e., for example, at least 90% of the nanoparticles have a size in the range of 2-50 nm, or in particular, at least 90% of the nanoparticles have a size in the range of 2-50 nm). The term "size" particularly relates to one or more of length, width, and diameter, depending on the shape of the nanoparticles. Typical dots are made of binary alloys such as cadmium selenide, cadmium sulfide, indium arsenide, and indium phosphide. However, the dots can also be made from ternary alloys (such as cadmium selenide sulfide). These quantum dots can contain as few as 100 to 100,000 atoms within the quantum dot volume, with a diameter of 10 to 50 atoms. This corresponds to approximately 2 to 10 nanometers. For example, spherical particles such as CdSe, InP, or CuInSe2 can be provided with a diameter of approximately 3 nm. Luminescent nanoparticles (uncoated) can have shapes such as spheres, cubes, rods, wires, disks, multi-pods, etc., with a size of less than 10 nm in one dimension. For example, CdSe nanorods can be provided with a length of 20 nm and a diameter of 4 nm. Thus, in one embodiment, the semiconductor-based luminescent quantum dots include core-shell quantum dots. In another embodiment, the semiconductor-based luminescent quantum dots include dot-in-rod nanoparticles. Combinations of different types of particles are also possible. Here, the term "different types" can refer to different geometries as well as different types of semiconductor luminescent materials. Thus, combinations of two or more of the quantum dots or luminescent nanoparticles (indicated above) are also possible.

[0081] In one embodiment, the nanoparticles may comprise semiconductor nanocrystals comprising a core comprising a first semiconductor material and a shell comprising a second semiconductor material, wherein the shell is disposed above at least a portion of the surface of the core. Semiconductor nanocrystals comprising a core and a shell are also referred to as "core / shell" semiconductor nanocrystals. Any of the materials indicated above may be used in particular as the core. Thus, the phrase "core-shell quantum dots having a core selected from the group consisting of..." applies to some of the above lists of quantum dot materials. The term "core-shell" may also refer to "core-shell-shell" and the like, including gradient alloy shells, or rod midpoints, and the like.

[0082] For example, a semiconductor nanocrystal can include a core having the formula MX, where M can be cadmium, zinc, magnesium, mercury, aluminum, gallium, indium, thallium, or a mixture thereof, and X can be oxygen, sulfur, selenium, tellurium, nitrogen, phosphorus, arsenic, antimony, or a mixture thereof. Examples of materials suitable for use as semiconductor nanocrystal cores include, but are not limited to, ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, MgS, MgSe, GaAs, GaN, GaP, GaSe, GaSb, HgO, HgS, HgSe, HgTe, InAs, InN, InP, InGaP, InSb, AlAs, AlN, AlP, AlSb, TlN, TlP, TlAs, TlSb, PbO, PbS, PbSe, PbTe, Ge, Si, alloys comprising any of the foregoing, and / or mixtures comprising any of the foregoing, including ternary and quaternary mixtures or alloys.

[0083] The shell can be a semiconductor material having a composition that is the same as or different from that of the core. The shell comprises an outer coating of semiconductor material on the surface of the core semiconductor nanocrystal and can include a Group IV element, a Group II-VI compound, a Group II-V compound, a Group III-VI compound, a Group III-V compound, a Group IV-VI compound, a Group I-III-VI compound, a Group II-IV-VI compound, a Group II-IV-V compound, an alloy comprising any of the foregoing, and / or a mixture comprising any of the foregoing, including ternary and quaternary mixtures or alloys. Examples include, but are not limited to, ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, MgS, MgSe, GaAs, GaN, GaP, GaSe, GaSb, HgO, HgS, HgSe, HgTe, InAs, InN, InP, InGaP, InSb, AlAs, AlN, AlP, AlSb, TlN, TlP, TlAs, TlSb, PbO, PbS, PbSe, PbTe, Ge, Si, alloys comprising any one of the aforementioned substances and / or mixtures comprising any one of the aforementioned substances. For example, ZnS, ZnSe or CdS outer coatings can be grown on CdSe or CdTe semiconductor nanocrystals. For example, outer coating processes have been described in United States Patent (USP) 6,322,901. By regulating the temperature of the reaction mixture during outer coating and monitoring the absorption spectrum of the core, the material of the outer coating with high emission quantum efficiency and narrow size distribution can be obtained. The outer coating can comprise one or more layers. The outer coating comprises at least one semiconductor material that is the same as or different from the component of the core. Preferably, the outer coating has a thickness of from about one to about ten monolayers. The outer coating may also have a thickness greater than ten monolayers. In one embodiment, more than one outer coating may be included on the core.

[0084] In one embodiment, the surrounding "shell" material may have a band gap that is larger than the band gap of the core material. In certain other embodiments, the surrounding shell material may have a band gap that is smaller than the band gap of the core material. In one embodiment, the shell may be selected so that the atomic spacing approximates the atomic spacing of the "core" substrate. In certain other embodiments, the shell and core materials may have the same crystal structure.

[0085] Examples of semiconductor nanocrystal (core) shell materials include, but are not limited to: red (e.g., (CdSe)ZnS (core) shell), green (e.g., (CdZnSe)CdZnS (core) shell, etc.), and blue (e.g., (CdS)CdZnS (core) shell) (see further above for examples of specific semiconductor-based wavelength converter nanoparticles).

[0086] Thus, in one embodiment, the luminescent particles comprise a luminescent material selected from the group consisting of luminescent quantum dots, wherein the luminescent quantum dots comprise one or more core materials selected from the group consisting of CdS, CdSe, ZnS, and ZnSe. Thus, in one embodiment, the luminescent particles may also be selected from the group consisting of luminescent nanoparticles, such as quantum dots or quantum rods of composition MX (M = Cd, Zn, X = Se, S). Such particles may have a number average particle size (i.e., particularly length / width / height, diameter) selected from the range of 1-50 nm.

[0087] As indicated above, the first coating layer is formed by a sol-gel type process, which generally has an average thickness in the range of 5-500 nm, in particular 10-500 nm, even more particularly 20-500 nm, even more particularly 50-300 nm. In this process, an inorganic network is formed from a homogeneous precursor solution by subsequent hydrolysis to form a sol (colloidal suspension) and then condensation to form a gel (crosslinked solid network), which is chemically bonded to the powder surface. Preferably, the first coating material is silicon dioxide, and the sol-gel deposition method corresponds to the so-called Stöber reaction as described in Stöber, W., A. Fink et al. "Controlled growth of monodisperse silica spheres in the micrometer size range", Journal of Colloid and Interface Science 26 (1): 62-69. For this purpose, the luminescent material is dispersed in an alcohol, such as an aliphatic alcohol R-OH, such as methanol CH3OH, ethanol C2H5OH or isopropanol C3H7OH, and then ammonia (NH3 solution in water) and a silicon alkoxide precursor are added. The silicon alkoxide precursor is dissolved in an alcohol and ammonia mixture and begins hydrolysis. The sol species dissolved by hydrolysis react with reactive groups on the particle surface (e.g., amine or silanol groups). A seeded growth process consisting of hydrolysis, nucleation, and condensation reaction steps then occurs, forming a conformal silica coating on the particle surface.

[0088] The silicon alkoxide precursor is selected from the group consisting of A group of compounds formed wherein: a) R1, R2, R3 are hydrolyzable alkoxy groups, and R4 is selected from the group consisting of C1-C6 linear alkyl groups, hydrolyzable alkoxy groups, and phenyl groups, or b) R1, R2, R3 are each selected from -OCH3 and -OC2H5, and R4 is selected from the group consisting of -CH3, -C2H5, -OCH3, -OC2H5, and phenyl groups. Optionally, the silicone-based polymer is obtained from a material selected from the group consisting of:

[0089] 、 、 and .

[0090] Therefore, the silicon alkoxide precursor is selected from the group that can be selected from this group. In particular, the silicon alkoxide precursor is selected from the group of Si(OCH3)4 or Si(OC2H5)4, and more particularly, Si(OC2H5)4 is used as the silicon alkoxide precursor. Similar precursors, but based on another metal (such as, for example, Al), can also be used.

[0091] A typical first coating process can include the following stages: (a) Suspending the luminescent powder in an alcohol-ammonia solution mixture while stirring or sonicating. To improve particle dispersion, the powder can also be mixed with alcohol and a small amount of silicon (or other metal) alkoxide before adding the ammonia solution. (b) Adding the silicon (or other metal) alkoxide precursor while agitating the suspension. Typical concentrations of silicon (or other metal) alkoxide, ammonia, and water in the alcohol solvent are 0.02-0.7, 0.3-1.5, and 1-16 mol / L, respectively. (c) Stirring or sonicating the suspension until a coating has formed. (d) Washing the coated powder with alcohol, drying it, and then calcining it at 200-300°C in air or vacuum.

[0092] Thus, in one embodiment, a sol-gel coating process comprises: (ia) providing a mixture of an alcohol, ammonia, water, a luminescent particle, and a metal alkoxide precursor, while agitating the mixture, and allowing a first coating to form on the luminescent particle, wherein the metal alkoxide precursor is particularly selected from the group consisting of titanium alkoxides, silicon alkoxides, and aluminum alkoxides; and (ib) recovering the luminescent particle from the mixture and optionally subjecting the luminescent particle to a heat treatment to provide the coated luminescent particle. The process of recovering the (coated) luminescent material from the mixture may, for example, comprise one or more of filtration, centrifugation, decanting (liquid from the precipitate), etc. The heat treatment may comprise one or more of drying and calcining, particularly both, i.e., a drying phase at a temperature in the range of 70-130°C, followed by a calcining phase (in air; or in vacuum or (other) inert atmosphere). Thus, during a portion of the heat treatment period, the (coated) luminescent material may be in an inert environment (such as vacuum, or one or more of N2 and an inert gas). The heat treatment appears to improve the stability of the luminescent material. Additionally, as indicated above, in the sol-gel coating process, a coating selected from the group consisting of A silicon (or other metal; although the above formula refers to Si) alkoxide (particularly a precursor) of the group consisting of compounds wherein R1, R2, and R3 are selected from the group consisting of hydrolyzable alkoxy moieties, and R4 is selected from the group consisting of C1-C6 linear alkyl moieties, hydrolyzable alkoxy moieties, and phenyl moieties. Optionally, other ligands besides alkoxides may be used in the precursor for the sol-gel process.

[0093] Particles obtained using a sol-gel coating process can optionally include more than one core. For example, in the case of quantum dots, agglomerates can be obtained with a sol-gel coating or first coating layer. Similarly, a silica precursor (or other metal oxide precursor) can also coat multiple QDs with a thin single shell to form coated agglomerates. This may depend, among other things, on the concentration of the quantum dots.

[0094] Precursors for sol-gel coating have been described above with particular reference to silicon alkoxide precursors. However, aluminum (or another metal) alkoxide precursor(s) may also be used. Furthermore, a combination of two or more chemically distinct precursors may be used to provide a sol-gel coating layer or first coating layer.

[0095] The term "first coating process" may also refer to multiple first coating processes. With multiple first coating processes, a layer (or layers) comprising essentially the same composition throughout the entire layer thickness can be provided (when, for example, in a first coating process, each coating stage or step comprises depositing essentially the same material), or a multilayer comprising two or more layers having different compositions can be provided, such as a stack of two or more (sol-gel) layers, each having two or more different compositions. Examples include SiO₂-Al₂O₃ (sol-gel) multilayers, such as a stack of three or more (sol-gel) layers, in which SiO₂ and Al₂O₃ alternate (see also above).

[0096] As indicated above, the second coating layer can typically have a layer thickness in the range of 5-250 nm, particularly 15-75 nm. This layer can be formed using an atomic layer deposition (ALD) process. In this process, the polymer network is formed by reacting a metal oxide precursor with an oxygen source (such as water and / or ozone in the gas phase). Unlike in sol-gel processes, the ALD reaction is divided into (at least) two steps. In the first step, the metal (oxide) precursor is introduced into the (ALD) reactor and adsorbs and / or reacts with reactive groups on the particle surface. The reactor is then purged to remove substantially all unreacted or adsorbed precursor molecules. In the second step, an oxygen source is introduced into the reactor and reacts with the metal source on the particle surface. The reactor is then purged to remove substantially all remaining oxygen source molecules and hydrolysis products formed by the condensation reaction. Due to the self-limiting nature of the surface reaction, these two steps result in the formation of an atomic layer (or monolayer). These atomic layer reaction steps are repeated multiple times to form the final ALD coating. The term "metal oxide precursor" specifically refers to a precursor of a metal oxide. The precursor itself may not be a metal oxide, but may, for example, include metal-organic molecules. Thus, metal (oxide) precursors, particularly for ALD, may typically include metal halides, alkoxides, amides, and other metal (organic) compounds.

[0097] The stepwise nature of the ALD process allows for easy deposition of defined layer thicknesses. The ALD process also allows for the deposition of layers of varying composition by sequentially introducing different metal oxide precursors into the reactor to form multi-component layers or nanolaminates. Thus, in specific embodiments, the second layer comprises multiple layers (see also below).

[0098] For the ALD process, in particular, a fluidized bed reactor can be used. Thus, in a specific embodiment, the second coating layer is provided by application of the atomic layer deposition process. In one embodiment, a static powder bed is used for the ALD coating of the sol-gel coated luminescent powder particles. However, a fluidized bed can also be used. Other types of reactors can also be used. By applying a first sol-gel coating with a structured nanoporous surface, particle agglomeration can be substantially prevented. The process can be easily scaled up, and almost no powder loss is observed during the ALD coating. Commercially available ALD reactors for powder coating are sold, for example, by Picosun Oy, which have, for example, a cartridge sample holder (POCA™). Systems that can be used for ALD are described, for example, in WO 2013171360 A1, but other systems can also be used.

[0099] A (non-limiting) number of suitable materials for the ALD second coating layer are listed in the following table:

[0100] Oxide materials Metal oxide precursors Oxygen source Deposition T[°C] <![CDATA[Al2O3]]> <![CDATA[Al(CH3)3 (TMA) or HAl(CH3)2]]> <![CDATA[H2O or O3]]> 100 – 400 <![CDATA[HfO2]]> <![CDATA[Hf(N(CH3)2)4 or Hf(N(CH2CH3)2)4]]> <![CDATA[H2O]]> 80 – 300 <![CDATA[Ta2O5]]> <![CDATA[TaCl5 or Ta(N(CH3)2)5]]> <![CDATA[H2O]]> 80 – 300 <![CDATA[ZrO2]]> <![CDATA[ZrCl4 or Zr(N(CH3)2)4]]> <![CDATA[H2O]]> 80 – 300 <![CDATA[TiO2]]> <![CDATA[TiCl4, Ti(OCH3)4 or Ti(OEt)4]]> <![CDATA[H2O]]> 80 – 300 <![CDATA[SiO2]]> <![CDATA[SiCl4, H2N(CH2)3Si(OEt)3 or Si(OEt)4]]> <![CDATA[H2O or O3]]> 150–300

[0101] Alternatively or additionally, niobium oxide (particularly Nb2O5) or yttrium oxide (Y2O3) can be used, the metal precursors of which are, for example, (tert-butylimino)-tris(diethylamino)-niobium, NbF5 or NbCl5, and tris(ethylcyclopentadienyl)yttrium, respectively.

[0102] However, other materials may also be used. Thus, in an atomic layer deposition process, the metal oxide precursor may be selected from the group of metal oxide precursors of a metal selected from the group consisting of Al, Hf, Ta, Zr, Ti, and Si. Alternatively or additionally, one or more of Ga, Ge, V, and Nb may be used. Even more particularly, alternating layers of two or more of these precursors are used, wherein at least one precursor is selected from the group consisting of an Al metal oxide precursor and a Si metal oxide precursor (particularly an Al metal oxide precursor), and another precursor is selected from the group consisting of an Hf metal oxide precursor, a Ta metal oxide precursor, a Zr metal oxide precursor, and a Ti metal oxide precursor, particularly from the group consisting of an Hf metal oxide precursor, a Ta metal oxide precursor, and a Zr metal oxide precursor, even more particularly a Ta metal oxide precursor. In particular, Hf, Zr, and Ta appear to provide relatively light-transmitting layers, while, for example, Ti may provide a relatively less light-transmitting layer. For example, processing of Ta, Hf, and Zr appears to be relatively easier than processing of Si. The term "oxide precursor" or "metal oxide precursor" or "metal (oxide) precursor" may also refer to a combination of two or more chemically different precursors that form oxides (and are therefore designated as metal oxide precursors) particularly when reacted with an oxygen source.

[0103] For example, silanol groups at the nanoporous surface of a sol-gel first coating layer (assuming a silica first coating layer) serve as reaction sites during the ALD of the initial layer. In one embodiment, aluminum oxide is deposited using Al(CH3)3 (TMA) as a metal oxide precursor and (subsequently exposed to) water as an oxygen source. In the first reaction step, TMA reacts with the surface silanol groups of the silica sol-gel layer according to the following chemical formula:

[0104] ≡Si-OH + Al(CH3)3→≡Si-O-Al(CH3)2 + CH4

[0105] The water then reacts with the metal oxide precursor in a second reaction step via a hydrolysis followed by condensation reaction as follows:

[0106] ≡Si-O-Al(CH3)2 +2H2O→≡Si-O-Al(OH)2 + 2 CH4

[0107] 2≡Si-O-Al(OH)2→≡Si-O-Al(OH)-O-Al(OH)-O-Si≡+H2O.

[0108] The results show that deposition temperatures in the range of 200-350° C. are most suitable for ALD of aluminum oxide on the first coating layer, with preferred temperatures in the range of 250-300° C. Similar temperatures can be applied for ALD of other metal oxide precursors for (multiple) ALD layers.

[0109] In particular, the ALD aluminum oxide (or other metal oxide) layer has a thickness of 5-120 nm, more particularly 10-75 nm, yet even more particularly 15-50 nm.

[0110] The water vapor permeation barrier properties of the aluminum oxide ALD layer can be further improved by depositing at least one additional layer of a different oxide material, such as ZrO2, TiO2, Y2O3, Nb2O5, HfO2, or Ta2O5. In particular, the thickness of the additional material layer is in the range of 1-40 nm, more preferably in the range of 1-10 nm. Even more preferred is a nanolaminated stack of alternating layers of Al2O3 and a second oxide material from the group of ZrO2, TiO2, Y2O3, Nb2O5, HfO2, and Ta2O5. A suitable nanolaminated stack can be, for example, 20×(1 nm Al2O3 (10 ALD cycles) + 1 nm ZrO2 (11 ALD cycles)) deposited at 250°C to form a 40 nm thick nanolaminated second coating layer on top of the first sol-gel coating.

[0111] In one embodiment, the present invention particularly provides a method wherein the second coating layer comprises a multilayer having layers with different chemical compositions, and wherein in the atomic layer deposition process, the metal oxide precursor is particularly selected from the group of metal oxide precursors of metals selected from the group consisting of Al, Hf, Ta, Zr, Ti, Si, Ga, Ge, V, and Nb, and in particular the metal oxide precursor is selected from the group of metal oxide precursors of metals selected from the group consisting of Al, Hf, Ta, Zr, Ti, and Si. Combinations of two or more of such precursors may also be used, for example, multilayers comprising aluminum oxide, mixed oxides of zirconium and hafnium, and aluminum oxide, etc.

[0112] Thus, in one embodiment, the second coating layer may comprise a multilayer having layers with different chemical compositions, and wherein the multilayer comprises one or more layers comprising oxides of one or more of Al, Hf, Ta, Zr, Ti, Si, Ga, Ge, V, and Nb, in particular wherein the multilayer comprises one or more layers comprising oxides of one or more of Al, Hf, Ta, Zr, Ti, and Si. One or more layers of such a multilayer may also comprise mixed oxides, such as indicated above.

[0113] In particular, the method is applied so as to obtain an (ALD) multilayer coating comprising at least two (ALD) layers ("AB"), even more particularly at least three layers (e.g. "ABA"), yet even more at least four layers. Yet more particularly, at least a stack of two or more stacks of a subset of two (ALD) layers ("AB") is applied, such as (AB) n , where n is 2 or greater, such as 2-20, for example 2-10.

[0114] In particular, at least one of the layers in the multilayer comprises one or more oxides of Al and Si (including combinations thereof), and at least one of the layers in the multilayer comprises one or more oxides of Hf, Ta, Zr, Ti, Ga, Ge, V and Nb. Such layers may also optionally comprise Al, Hf, Ta, Zr, Ti, Si, Ga, Ge, V and Nb, wherein Si or Al together with one or more of the other indicated elements are in one layer when the other(s) layer(s) in the multilayer comprise oxides of silicon dioxide or aluminum oxide, respectively. The term "ALD multilayer" or "multilayer" as indicated above particularly refers to layers having different chemical compositions. The phrase "layers having different chemical compositions" indicates that there are at least two layers having different chemical compositions, such as in the case of "ABC", or in (AB) n under the circumstances.

[0115] (AB) nSpecific examples include multilayers, wherein A is selected from one or more oxides of Si and Al (particularly Al), and wherein B is selected from one or more oxides of Al, Hf, Ta, Zr, Ti, Si, Ga, Ge, V and Nb, wherein Si or Al together with one or more of the other indicated elements are in one layer when the other layer(s) of the multilayer comprise oxides of silicon dioxide or aluminum oxide, respectively, in particular, wherein B is selected from one or more oxides of Hf, Ta, Zr, Ti, Ga, Ge, V and Nb, yet even more particularly, wherein B is selected from one or more oxides of Hf, Ta, Zr and Ti, more particularly, wherein B is selected from one or more oxides of Hf, Ta and Zr.

[0116] Thus, the ALD multilayer is in particular provided on a sol-gel layer. Additionally, as indicated above, on top of the ALD multilayer, one or more further layers may optionally be applied.

[0117] Thus, in particular embodiments, the second coating layer comprises a multilayer comprising a stack of layers wherein adjacent layers have different chemical compositions.

[0118] In particular, each layer of the multilayer independently has a thickness in the range of 1-40 nm, in particular 1-10 nm. In addition, in particular, the multilayer comprises one or more aluminum oxide layers and one or more metal oxide layers, wherein the metal is selected from the group of Hf, Ta, Zr and Ti.

[0119] Thus, in a specific embodiment of the atomic layer deposition process, a metal oxide precursor and an oxygen source are applied, the metal oxide precursor being selected from the group consisting of Al(CH3)3, HA1(CH3)2, Hf(N(CH3)2)4, Hf(N(CH2CH3)2)4, Hf[N(CH3)(CH2CH3)]4, TaCl5, Ta(N(CH3)2)5, Ta{[N(CH3)(CH2CH3)]3N(C(CH3)3)}, ZrCl4, Zr(N(CH3)2)4, TiCl4, Ti(OCH3)4, Ti(OCH2CH3)4, SiCl4, H2N(CH2)3Si(OCH2CH3)3 and Si(OCH2CH3)4, and the oxygen source being selected from the group consisting of H2O and O3. As indicated above, two or more different metal oxide precursors and / or two or more different oxygen sources may also be applied.

[0120] In another embodiment of the method in an atomic layer deposition process, a multilayer having layers with different chemical compositions is provided, wherein one or more layers include tantalum oxide (particularly Ta2O5). Therefore, in one embodiment, the present invention further provides a luminescent material, wherein the second coating layer includes a multilayer having layers with different chemical compositions, wherein one or more layers may specifically include Ta2O5. In another embodiment of the method in an atomic layer deposition process, a multilayer having layers with different chemical compositions is provided, wherein one or more layers include one or more of tantalum oxide (particularly Ta2O5), hafnium oxide, and zirconium oxide. Therefore, in one embodiment, the present invention further provides a luminescent material, wherein the second coating layer includes a multilayer having layers with different chemical compositions, wherein one or more layers may specifically include one or more of tantalum oxide, hafnium oxide, and zirconium oxide. For example, the multilayer stack may also include a stack having alternating layers, wherein, for example, aluminum oxide alternates with one or more of tantalum oxide (particularly Ta2O5), hafnium oxide, and zirconium oxide, such as, for example, a stack comprising aluminum oxide-tantalum oxide-aluminum oxide-hafnium oxide-aluminum oxide-tantalum oxide, etc.

[0121] Furthermore, it appears that when an ALD coating is applied first to the luminescent material particles (thus, for example, before a subsequent sol-gel layer), the ALD layer is less uniform than desired. Consequently, to obtain a good ALD layer, the ALD layer thickness may need to be increased more than is generally necessary, which can lead to an unnecessary (even if small) reduction in transmission. Furthermore, it appears that an ALD coating is more easily applied to a sol-gel-derived coating, whereas a sol-gel coating may be less easily applied to an ALD coating. Furthermore, a sol-gel process applied to an ALD layer may be detrimental to the ALD layer.

[0122] The use of a final layer (i.e., a layer further away from the luminescent core comprising a metal oxide layer, wherein the metal is selected from the group consisting of Hf, Ta, Zr, and Ti) appears to be particularly beneficial in terms of stability. In addition, the use of thin individual layers (such as thinner than about 10 nm, such as at least 5 nm, for example at least 1 nm) also appears to increase the stability of the luminescent material.

[0123] The total layer thickness of the second coating layer is therefore in particular in the range of 5-250 nm, such as 10-200 nm, in particular for example 15-120 nm, such as 15-50 nm, for example 20-75 nm.

[0124] When a non-oxide luminescent material is used, an oxygen-containing layer may form on the particles of the luminescent material during and / or prior to the method of the present invention, particularly during the first coating process, thereby forming an intermediate oxygen-containing layer between the core and the first coating layer. Thus, in another embodiment, the luminescent core comprises a non-oxide, and an intermediate oxide layer is present between the luminescent core and the first coating layer. The thickness of this intermediate layer may be in the range of 0.5-50 nm, such as 1-20 nm.

[0125] The layer thicknesses described herein are in particular average layer thicknesses. However, in particular, at least 50% (even more particularly at least 80%) of the area of ​​the respective layer has the layer thickness indicated in this manner. In particular, this means that such a thickness is to be found in at least 50% of the area of ​​such a layer.

[0126] The first coating layer and the second coating layer are light-transmissive, which means that at least a portion of the light impinging on each layer passes through the corresponding layer. Therefore, the first layer and the second layer can be completely or partially transparent, or can be translucent. More than 90% of the (visible) light impinging on the coating layer can pass through the coating layer. Due to the properties of the material from which the coating layer is made, the first coating layer and / or the second coating layer can be light-transmissive. For example, the coating layer can be made of a transparent material even if the layer is relatively thick. The first coating layer and / or the second coating layer are thin enough so that the corresponding layer becomes light-transmissive, while the material from which the layer is made is opaque or translucent when made into a relatively thick layer. The materials described herein are all transmissive for (visible) light, or can be made into a suitable layer thickness for (visible) light transmission.

[0127] A lighting device includes a light source configured to generate light source radiation, particularly one or more of blue and UV; and a wavelength converter comprising a luminescent material as described herein, wherein the wavelength converter is configured to convert at least a portion of the light source radiation into wavelength converter light (such as one or more of green, yellow, orange, and red light). The wavelength converter is particularly radiation-coupled to the light source. The term "radiation-coupled" particularly means that the light source and the luminescent material are associated with each other such that at least a portion of the radiation emitted by the light source is received by the luminescent material (and at least partially converted into luminescence). Thus, the luminescent cores of the particles can be excited by the light source radiation, thereby providing luminescence of the luminescent material in the cores. In one embodiment, the wavelength converter comprises a matrix (material) containing the luminescent material (particles). For example, the matrix (material) may include one or more materials selected from the group consisting of a transmissive organic material support, such as PE (polyethylene), PP (polypropylene), PEN (polyethylene naphthalate), PC (polycarbonate), polymethacrylic acid (PMA), polymethyl methacrylate (PMMA) (Plexiglas or Perspex), cellulose acetate butyrate (CAB), silicone, polyvinyl chloride (PVC), polyethylene terephthalate (PET), (PETG) (ethylene glycol-modified polyethylene terephthalate), PDMS (polydimethylsiloxane), and COC (cyclic olefin copolymer). Alternatively or additionally, the matrix (material) may include an epoxy resin.

[0128] The lighting device can be part of or can be used in the following systems: for example, office lighting systems, home application systems, store lighting systems, home lighting systems, accent lighting systems, spot lighting systems, theater lighting systems, fiber 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, decorative lighting systems, portable systems, automotive applications, greenhouse lighting systems, horticultural lighting or LCD backlighting.

[0129] As indicated above, the lighting unit can be used as a backlighting unit in an LCD display device. Therefore, the present invention also provides an LCD display device comprising a lighting unit as defined herein, configured as a backlighting unit. In another aspect, the present invention also provides a liquid crystal display device comprising a backlighting unit, wherein the backlighting unit comprises one or more lighting devices as defined herein.

[0130] In particular, the light source is a light source that, during operation, emits (light source radiation) light at least at a wavelength selected from the range of 200-490 nm, and in particular, at least at a wavelength selected from the range of 400-490 nm, even more particularly, at 440-490 nm. This light can be used in part by wavelength converter nanoparticles (see further below). Thus, in a specific embodiment, the light source is configured to generate blue light. In a specific embodiment, the light source comprises a solid-state LED light source (such as an LED or a laser diode). The term "light source" may also refer to a plurality of light sources, such as 2-20 (solid-state) LED light sources. Thus, the term LED may also refer to a plurality of LEDs. The term white light herein is known to those skilled in the art. It particularly relates to light having a correlated color temperature (CCT) between about 2000 and 20000 K, in particular between 2700-20000 K, in particular in the range of about 2700 K and 6500 K for general lighting, and in particular in the range of about 7000 K and 20000 K for backlighting purposes, and in particular within about 15 SDCM (standard deviation of color matching) of the BBL (black body locus), in particular within about 10 SDCM of the BBL, even more particularly within about 5 SDCM of the BBL. In one embodiment, the light source may also provide light source radiation having a correlated color temperature (CCT) between about 5000 and 20000 K (e.g., direct phosphor-converted LEDs (blue-emitting diodes with a thin phosphor layer, for example, to obtain 10000 K)). Therefore, in a particular embodiment, the light source is configured to provide light source radiation having a correlated color temperature in the range of 5000-20000 K, even more particularly in the range of 6000-20000 K, such as 8000-20000 K. An advantage of a relatively high color temperature may be that a relatively high blue component may be present in the light source radiation.

[0131] Figure 4A lighting device 20 is schematically depicted and includes a light source 10 configured to generate light source radiation 11, particularly one or more of blue and UV, and a wavelength converter 30 comprising a luminescent material 1 having particles as defined herein. The wavelength converter 30 may, for example, comprise a matrix (such as a silicone or organic polymer matrix) in which the coated particles are embedded. The wavelength converter 30 is configured to convert at least a portion (wavelength) of the light source radiation 11 into wavelength converter light 21, which comprises at least wavelength converter light 31 and optionally also the light source radiation 11. The wavelength converter light 31 comprises at least luminescence from the coated particles described herein. However, the wavelength converter 30 may optionally also comprise one or more other luminescent materials. The wavelength converter 30, or more particularly the luminescent material 1, may be arranged at a non-zero distance d3, such as a distance of 0.1-100 mm. However, the distance may alternatively be zero, such as when the luminescent material is embedded in a dome on an LED die. The distance d3 is the shortest distance between the light emitting surface of the light source (such as an LED die) and the wavelength converter 30 (more particularly the luminescent material 1 ).

[0132] Figure 5a Schematically depicted are luminescent powder particles with a sol-gel first coating that form a static powder bed during the ALD of a second coating. The particles are indicated by reference numeral 100, and the sol-gel coating or first coating layer is indicated by reference numeral 110. The luminescent core is indicated by reference numeral 102 and may comprise, for example, micron-sized particles of a luminescent nitride or sulfide phosphor, but may also comprise other (smaller) materials such as luminescent nanoparticles (see also Figure 5c ).like Figure 5a As schematically shown in FIG, the outer shape of the first coating layer 110 may have a slightly concave shape, as seen in SEM. By way of example, Figure 5a The smaller particles in the luminescent particle 100 indicate, for example, an ALD precursor (see below). Reference numeral 100 a is used to indicate a luminescent particle 100 having only a sol-gel first coating layer 110 .

[0133] Figures 5b-5d Some other aspects of the particulate luminescent material are schematically depicted; Figure 5b A luminescent material 1 is shown, here by way of example, showing two particles having a luminescent core 102, as well as a first coating layer 110 (formed by sol-gel coating) having a thickness d1 and a second coating layer 120 (formed by ALD) having a thickness d2. The thicknesses are not necessarily to scale. Possible recesses in the first coating layer 110 are not depicted. Thickness d1 can specifically be an average thickness averaged over the first coating layer 110; the same applies to the second thickness d2, etc. (see also below).

[0134] Figure 5c A luminescent core 102 comprising a luminescent nanoparticle, here, by way of example, a quantum dot 130, is schematically depicted. The quantum dot in this example comprises a quantum rod having a (semiconductor) core material 106, such as ZnSe, and a shell 107, such as ZnS. Of course, other luminescent nanoparticles can also be used. Such luminescent quantum dots 130 can also be provided with a hybrid coating.

[0135] As indicated above, the coating layer may comprise multiple layers; in particular, the second coating layer 120 may comprise a multi-layer coating. Figure 5d Schematically shown in FIG, wherein the second coating layer 120 includes an ALD multilayer 1120 having a layer 1121. Reference numerals 1121a, 1121b, and 1121c schematically indicate individual layers, which may be, for example, alternating Al2O3 layers (in the example of 1121b) and Ta2O5 layers (in the example of 1121a, 1121c), respectively. Reference numeral d2 indicates the thickness of the entire second coating layer 120. Each ALD layer may, for example, have a thickness in the range of 0.5-20 nm.

[0136] Figure 5d The reference numerals 17, 27, 37, 47, and 57 designate the surfaces of the respective layers. As indicated above, the layer thicknesses described herein are in particular average layer thicknesses. In particular, at least 50% (even more particularly at least 80%) of the area of ​​the respective layer has the layer thickness indicated in this manner. Thus, with reference to the thickness d2 between surface 17 and surface 47, below at least 50% of surface 17, layer thicknesses in the range of, for example, 5-250 nm can be found, while in other cases below at least 50% of surface area 17, smaller or larger thicknesses can be found, for example, but the average d2 of the second (multi-layer) coating 120 is within the indicated range of 5-250 nm. This applies similarly to the other thicknesses indicated herein. For example, with reference to the thickness d1 between surface 47 and surface 57, this thickness may be in the range of 20-500 nm in cases exceeding at least 50% of the area of ​​47, while in other cases less than at least 50% of the surface area 47, for example, smaller or larger thicknesses may be found, but the average d1 of the first layer 110 is in the indicated range of 5-500 nm, such as in particular 20-500.

[0137] Figures 5a-5d A luminescent particle 100 having a single core is schematically depicted. However, alternatively, aggregates can also be formed that are encapsulated with a first and a second coating layer. This can be particularly suitable for quantum dots as luminescent cores.

[0138] Figure 6aThe relative light output of the phosphor powders before (SiO2 alone) and after ALD coating (Al2O3 on SiO2) is shown as a function of degradation time (in hours); degradation conditions: 60°C / 100% relative humidity; ALD-1: 20 nm Al2O3 on the phosphor; ALD-2: 40 nm Al2O3 on the phosphor; ALD-3: 20 nm Al2O3 deposited on the SiO2 coating; SiO2-1: sol-gel SiO2 coating on the phosphor (the basis for ALD-3). Clearly, the sol-gel-coated or ALD-coated materials alone are inferior to the hybrid coatings.

[0139] Figure 6b The relative light output (85°C / 100% RH) is shown as a function of degradation time in hours; ALD-3: 20 nm Al2O3 on a SiO2 coating; ALD-4: 20 nm Al2O3 / Ta2O5 nanolaminate deposited on a thin (<10 nm) SiO2 layer; ALD-5: 20 nm Al2O3 / Ta2O5 nanolaminate deposited on a SiO2 coating; ALD-6: 20 nm Al2O3 / HfO2 nanolaminate deposited on a SiO2 coating. From these figures, it can be concluded, among other things, that ALD multilayers of Al2O3 and a second oxide offer superior performance to "simple" Al2O3 ALD coatings. Figure 6a The ALD-3 samples in Figure 6b are the same in ; however, the measurement conditions (temperature) are different.

[0140] Figure 6c The relative light output (LO) as a function of degradation time in hours (85°C / 100% RH) is shown for ALD-3 and ALD-6: samples as described above; ALD-7: with a 20 nm Al2O3 / HfO2 nanolaminate on a thin (<10 nm) SiO2 layer (nanolamite design: 4×[1.5 nm Al2O3 / 3.5 nm HfO2]); and ALD-8: with a 10 nm Al2O3 / HfO2 nanolaminate on a thin (<10 nm) SiO2 layer (nanolamite design: 2×[1.5 nm Al2O3 / 3.5 nm HfO2]. It is clear that nanolaminates with thicker sol-gel layers and / or more stacks provide better results than those with thin sol-gel layers or multilayer stacks with only a few layers. ALD-5 and ALD-6 have sol-gel coatings in the range of approximately 100-200 nm.

[0141] Although specific implementations have been disclosed, these are examples only and should not be considered limiting. Various modifications and combinations of features of the disclosed implementations are within the scope of the following claims.

[0142] Having described the embodiments in detail, those skilled in the art will recognize that, given this description, modifications may be made to the embodiments described herein without departing from the spirit of the inventive concept. Therefore, it is not intended that the scope of the present invention be limited to the specific embodiments illustrated and described.

Claims

1. A method comprising: depositing a plurality of luminescent particles onto an assembly to form a film, the film comprising a plurality of layers of the luminescent particles, the assembly being configured to emit light at a first wavelength, the luminescent particles being configured to absorb light at the first wavelength and in response emit light at a second wavelength; and depositing an inorganic coating onto the plurality of luminescent particles using a low pressure deposition technique, the inorganic coating bonding the plurality of luminescent particles to each other and to the assembly, the inorganic coating having a coefficient of thermal expansion substantially matching that of the plurality of luminescent particles and a refractive index substantially matching that of the plurality of luminescent particles, The luminescent particles include a luminescent core, a first coating, and a second coating. The material of the first coating includes one or more of silicon oxide and Al2O3. The material of the second coating includes an oxide containing one or more of Al, Hf, Ta, Zr, Ti, and Si. The thickness of the first coating is greater than the thickness of the second coating. The first coating is a sol-gel coating, and the second coating is an atomic layer deposition coating.

2. The method according to claim 1, wherein the inorganic coating is an oxide coating. 3 . The method of claim 1 , wherein the luminescent particles are deposited on the component using one of sedimentation, electrophoresis, stencil printing, and dispensing techniques. The method of claim 1 , wherein the luminescent particles are phosphor particles. The method of claim 1 , wherein the luminescent particles are quantum dots. The method according to claim 1 , wherein the low pressure deposition technique is an atomic layer deposition technique. The method of claim 1 , wherein the inorganic coating comprises a plurality of layers.

8. The method of claim 1, wherein the coefficient of thermal expansion of the inorganic coating substantially matches the coefficient of thermal expansion of the component.

9. The method of claim 1, wherein the refractive index of the inorganic coating is substantially matched to the refractive index of the component.

10. A device comprising: components, including openings; Multiple luminous particles; as well as an inorganic coating on the luminescent particles, the inorganic coating bonding the luminescent particles to each other and to the assembly to form a film of the luminescent particles on the assembly, The light emitting particles are configured to absorb light of a first wavelength and emit light of a second wavelength in response, and the light of the second wavelength is emitted through the opening. The device of claim 10 , wherein the film of light emitting particles on the component comprises multiple layers of light emitting particles.

12. The device of claim 11, wherein the component is a light emitting device.

13. A method comprising: roughening the surface of the first component or forming grooves in the surface of the first component; depositing an inorganic coating onto the surface of the first component using a low pressure deposition technique; as well as The first component is bonded to a second component, the inorganic coating promoting bonding of the first component to the second component, wherein the first component is one of a metal, a ceramic, a ceramic phosphor, a semiconductor, a light emitting device, and an insulator, and the second component is one of a metal, a ceramic, a ceramic phosphor, a semiconductor, a light emitting device, and an insulator.

14. The method of claim 13, wherein the first component comprises a light-emitting layer, and wherein the second component comprises a ceramic phosphor layer.

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