Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V9/00—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters
  • F21V9/30—Elements containing photoluminescent material distinct from or spaced from the light source
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
  • C09K11/06—Luminescent, e.g. electroluminescent, chemiluminescent materials containing organic luminescent materials
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21K—NON-ELECTRIC LIGHT SOURCES USING LUMINESCENCE; LIGHT SOURCES USING ELECTROCHEMILUMINESCENCE; LIGHT SOURCES USING CHARGES OF COMBUSTIBLE MATERIAL; LIGHT SOURCES USING SEMICONDUCTOR DEVICES AS LIGHT-GENERATING ELEMENTS; LIGHT SOURCES NOT OTHERWISE PROVIDED FOR
  • F21K9/00—Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
  • F21K9/60—Optical arrangements integrated in the light source, e.g. for improving the colour rendering index or the light extraction
  • F21K9/64—Optical arrangements integrated in the light source, e.g. for improving the colour rendering index or the light extraction using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V13/00—Producing particular characteristics or distribution of the light emitted by means of a combination of elements specified in two or more of main groups F21V1/00 - F21V11/00
  • F21V13/02—Combinations of only two kinds of elements
  • F21V13/08—Combinations of only two kinds of elements the elements being filters or photoluminescent elements and reflectors
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B33/00—Electroluminescent light sources
  • H05B33/12—Light sources with substantially two-dimensional radiating surfaces
  • H05B33/14—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of the electroluminescent material, or by the simultaneous addition of the electroluminescent material in or onto the light source
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
  • F21Y2105/00—Planar light sources
  • F21Y2105/10—Planar light sources comprising a two-dimensional array of point-like light-generating elements
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
  • F21Y2115/00—Light-generating elements of semiconductor light sources
  • F21Y2115/10—Light-emitting diodes [LED]
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
  • F21Y2115/00—Light-generating elements of semiconductor light sources
  • F21Y2115/30—Semiconductor lasers
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/85—Packages
  • H10H20/851—Wavelength conversion means
  • H10H20/8514—Wavelength conversion means characterised by their shape, e.g. plate or foil

Definitions

• the invention relates to a lighting device comprising (a) a light source, for producing light source light, and (b) a transparent converter device, as well as to such converter device per se.
• Luminescent materials in matrices are known in the art.
• US2006055316 for instance describes color electroluminescent displays comprising a sub-pixel structure and method for making the same.
• the sub-pixel structure has an electroluminescent phosphor, which emits blue light, and a photo luminescent phosphor, which emits at least one other color as a result of absorption of the blue light.
• US2006055316 also describes such photo luminescent phosphor materials.
• this document describes a method for making a photo luminescent phosphor material, the method comprising mixing a pigment powder and a matrix material to provide a uniform dispersion of the pigment powder in the matrix material, wherein the pigment material comprises a solid solution of organic photo luminescent molecules, the matrix material being chemically and physically compatible with the pigment powder such that the photo luminescent efficiency of the organic photo luminescent molecules are substantially maintained.
• the luminescent material such as organic luminescent molecules
• a matrix herein also called “second matrix”, or “second polymer containing matrix”
• the luminescent material is (molecularly) dispersed and may have a good photo-chemical stability.
• particles such as for instance flakes etc. of this material can be produced and then dispersed it in another matrix (herein also called “first matrix”, or “first polymer containing matrix”) to produce a composite transparent converter device, for instance with high flexibility, but also good luminescence and photo-chemical stability.
• the first polymer containing matrix has preferably a relatively low oxygen transmission rate and a relatively high transparency.
• particles of luminescent material such as luminescent molecules in a polymer containing matrix dispersed in a polymeric binder.
• the particles can be dispersed for example in a mainly water based dispersion and applied to various surfaces which can be used for light conversion. In this way, currently used inorganic luminescent material processing platform is maintained avoiding also environmental issues.
• particles of luminescent materials such as luminescent molecules
• dispersed in a polymeric binder can also be of advantage when for instance shaped forms need to be coated (for instance with a protective coating, see also below).
• the invention provides a lighting device comprising (a) a light source, for producing light source light, and (b) a transparent converter device, for converting at least part of the light source light, wherein the transparent converter device (herein also indicated as “converter device”) comprises a first polymer containing matrix containing discrete particles, wherein the discrete particles (herein also indicated as “particles”) comprise a second polymer containing matrix with luminescent material dispersed therein.
• the second polymer containing matrix is contained as particles (such as flakes) in the first polymer containing matrix.
• Such converter device may be stable, may be efficient, may be flexible, may be applied in a relatively easy way, etc.
• the first matrix may also function as a barrier, e.g. oxygen barrier, which may for instance be beneficial in view of lifetime improvement (of the luminescent material).
• the invention provides such transparent converter device per se, i.e. a transparent converter device, for converting at least part of light source light, comprising a first polymer containing matrix containing discrete particles, wherein the discrete particles comprise a second polymer containing matrix with luminescent material dispersed therein.
• matrix is used herein to indicate a layer or body or particle, which hosts another material, such as the first matrix being a matrix for the second matrix, and the second matrix being a matrix for the luminescent material.
• the transparent converter device may be a layer, for instance coated to a transparent support.
• the transparent converter device may also be self supporting, and for instance be a plate or a flexible entity.
• the transparent converter device may include an inorganic or an organic luminescent material, or a combination thereof.
• the term "luminescent material” may also relate to a plurality of luminescent materials.
• Organic luminescent materials are herein also indicated as organic dyes.
• the luminescent material comprises an inorganic luminescent material, selected from the group consisting of a lanthanide based luminescent material, a transition metal based luminescent material and a quantum dot material.
• inorganic luminescent materials known from solid state lighting or from low- pressure or high-pressure lamps, or from plasma applications may be applied.
• Inorganic materials that for instance may be applied are trivalent cerium doped garnet systems, such as YAG:Ce 3+ , and divalent Eu doped thiogallates, such as SrGa 2 S4:Eu 2+ , and sulfides, such as SrS:Eu 2+ , all well known in the art (see for instance US 7,115,217 or US 6,850,002). Also quantum dots (QD) may be applied.
• QD quantum dots
• the luminescent material comprises an organic dye (also known as organic phosphor organic luminescent material).
• the organic luminescent material may for instance comprise one or more perylene derivatives such as materials known as names Lumogen F Yellow 083, Lumogen F Yellow 170, Lumogen F Orange 240, Lumogen F Red 305, Lumogen F Blue 650, which may for instance be provided by BASF.
• Organic luminescent materials are currently being considered for remote luminescent material applications where blue light emitting diodes are used for pumping for instance green to red emitting luminescent material in order to obtain white light.
• Organic luminescent materials may have a number of advantages as compared with inorganic luminescent materials.
• the position and the band width of the luminescence spectrum can be designed with ease to be anywhere in the visible range to obtain high efficacy. They can also show much less light scattering and higher quantum efficiency further improving the system efficiency.
• organic luminescent material is in flexible configurations.
• the organic luminescent material is in an
• an inorganic luminescent material may be applied, or a combination of an inorganic luminescent material and an organic luminescent material.
• the first polymer containing matrix relates to a matrix which comprises a first polymer.
• the matrix may comprise also other components.
• the first matrix essentially consists of the first polymer.
• the first polymer containing matrix may in an embodiment comprise a binder containing coating layer.
• the polymer containing matrix is first provided as coating layer, especially comprising polymeric binders.
• the coating layer may be provided to a support, such as a transparent support, and after applying the coating, the coating may be dried or cured.
• a coating layer may be provided, like in classical lighting applications using luminescent material coating layers.
• the first matrix does not contain luminescent particles or molecules per se, but polymer matrix particles which have therein dispersed luminescent material.
• the first matrix may also contain luminescent material (thus in addition to the luminescent material comprised by the second matrix particles), see also below.
• the first polymer containing matrix comprises a binder containing coating layer.
• Typical binders are for instance acrylate binders, epoxy binders and polyviny alcohol (PVA) binders.
• the first polymer containing matrix may be a matrix comprising on one or more of acrylate binders, epoxy binders and polyviny alcohol (PVA) binders.
• first polymer containing matrix may in an embodiment especially refer to a hardened or cured layer.
• the layer thus provided may be continuous or discontinuous.
• the coating layer may contain (small) cracks, and thus be considered discontinuous.
• the first polymer containing matrix may especially be a matrix comprising one or more of a poly urethane, a polyalkane, a polyacrylate and a siloxane (such as a polydimethyl siloxane (PDMS)).
• a poly urethane such as a polyalkane (PDMS)
• PDMS polydimethyl siloxane
• the first polymer containing matrix is a flexible matrix.
• the transparent converter device may be a flexible unit.
• the second polymer containing matrix relates to a matrix which comprises a second polymer.
• the matrix may comprise also other components.
• the second matrix essentially consists of the second polymer.
• the second polymer containing matrix i.e. the matrix that is the building material of the particles, may especially be a matrix comprising on one or more polymers selected from the group consisting of PEN (polyethylene napthalate), PC (polycarbonate), polymethylacrylate (PMA), polymethylmethacrylate (PMMA) (Plexiglas or Perspex), cellulose acetate butyrate (CAB), polyvinylchloride (PVC), polyethyleneterephthalate (PET) (and its copolymers), (PETG) (glycol modified polyethyleneterephthalate), COC (cyclo olefin copolymer), and polystyrene.
• PEN polyethylene napthalate
• PC polycarbonate
• PMA polymethylacrylate
• PMMA polymethylmethacrylate
• CAB cellulose acetate butyrate
• PVC polyvinylchloride
• PET polyethyleneterephthalate
• COC cyclo olefin copolymer
• the chemical composition of the first polymer is substantially different from the second polymer.
• the chemical composition of the first matrix is different from the second matrix (even irrespective of the luminescent material).
• the first polymer containing matrix comprises a first polymer and the second polymer containing matrix comprises a second polymer, and the first and the second polymer are substantially different.
• organic luminescent materials are not included in this comparison (although their wt.% in the second matrix may be relatively small, see below).
• the weight percentage of such substantial identical polymers will at least in one matrix be lower than 50 wt.%, especially lower than 20 wt.%, especially lower than 10 wt.%.
• the first and second matrix are substantially different, with the weight percentage of substantial identical polymers in one phase being substantially lower than 5 wt.%, like for instance when the first matrix is based on PDMS and the second matrix is based on PMMA (substantially 0 wt.% substantially identical polymers).
• concentrations of (organic) luminescent (molecules) in the second polymer containing matrix may range from 0.00001 wt% up to 5 wt% (relative to the total weight of the first matrix.
• the particles, such as flakes may contain a combination of organic luminescent molecules.
• concentration may even range from 1 ppm by weight up to 1% wt with respect to the second polymer containing matrix.
• concentration can range from 1 wt.% to 50 wt.% with respect to the second polymer containing matrix.
• the concentration of the particles of the second polymer containing matrix in the first polymer containing matrix may be in to range 1-90 wt.% (relative to the total weight of the first and second matrix), such as in the range of 2-70 wt.%, like at least 5 wt.%.
• a white emitting lighting device with a desired correlated color temperature (CCT) and color rendering index (CRI)
• CCT correlated color temperature
• CRI color rendering index
• the second polymer matrix can be made by processed known in the art, in the presence of the luminescent material, for instance by providing a mixture comprising monomers and the luminescent material and polymerizing the mixture. After polymerizing, the product may be (laser) cut, or milled, etc. into particles. The mixture may also be hardened in cavities having the desired shape for the final particles (mould).
• the discrete particles may have dimensions in the range of 0.1 ⁇ - 5 mm.
• the particles may have any desired shape, such as spherical, cubic, star-like, cylindrical, etc.
• the converter device may also comprise differently shaped discrete particles. In order to facilitate a homogeneous conversion of the light over the converter device, it might be beneficial to use non-spherical particles, but to use particles having an aspect ratio larger than 1.
• the aspect ratio is the ratio length/width.
• the discrete particles have length/width aspect ratios of at least 2, especially at least 10. Different particles may have different aspect ratios.
• the converter device may comprise a plurality of particles having different aspect ratios.
• the particles are indicated as "discrete", since the particles can be distinguished from the first matrix. Boundaries between particles and first matrix can be observed and difference in chemical composition between first matrix and particle can be evaluated.
• the light source which is used in the lighting device to provide light source light to the converter device, may at least partially be embedded in the transparent converter device.
• a self-supporting converter device may comprise one or more indentations or cavities, to host at least partially one or more light source(s), respectively.
• the light source and converter device may be configured to provide light source light in an edge of the converter device.
• the light source may be in contact with the converter device but may also be arranged at a non-zero distance from the converter device.
• the light source comprises a solid state LED light source.
• the light source comprises a laser diode.
• an array of light sources is applied to illuminate the converter device. Combinations of different types of light sources may be applied.
• the converter device may have any shape, such as a layer or a self supporting body. It may be flat, curved, shaped, squared, round hexagonal, spherical tubular, cubic, etc.
• the self supporting body may be rigid or flexible.
• the thickness may in general be in the range of 0.1-10 mm.
• the length and/or width (or diameter) may be in the range of for instance 0.01-5 m, such as 0.02-5 m, for instance 0.1-50 mm.
• polymeric luminescent particles such as flakes
• Such particles, such as flakes may for instance be obtained by protecting a luminescent foil at one or preferably both sides, with a barrier layer and subsequently cutting such coated foil into particles, such as (high aspect ratio) flakes.
• the transparent converter device (with for instance flakes) may include (incorporated in the first matrix (and/or in the first matrix)) additional materials, such as getters to improve lifetime.
• the discrete particles and/or the converter device further comprise a coating layer for improving the life-time of the luminescent material.
• the coating layer reduces the transport of oxygen into the discrete particle resulting in a slower degradation of the luminescent material. In this way the coating layer improves the life time of the luminescent material and hence that of the converter device.
• the first polymer containing matrix of the transparent converter device or the lighting device has an oxygen transmission rate of equal to or less than 50 cm 3 /m 2 -day-bar, preferably equal to or less than 25 cm 3 /m 2 -day-bar, more preferably equal to or less than 5 cm 3 /m 2 -day-bar, even more preferably equal to or less than 1 cm 3 /m 2 -day-bar.
• the transparent converter device may comprise particles comprising an organic luminescent material while inorganic luminescent material is comprised (directly) by the first matrix. In an embodiment, this may also be the other way around.
• the particles comprise flakes, and the flakes consist of multiple layers.
• the converter device i.e. especially the first matrix
• upstream and downstream relate to an arrangement of items or features relative to the propagation of the light from a light generating means (here the especially the light source), wherein relative to a first position within a beam of light from the light generating means, a second position in the beam of light closer to the light generating means is “upstream”, and a third position within the beam of light further away from the light generating means is "downstream”.
• the term "transparent" herein may especially refer to a converter device that has a light transmission in the range of 90-100 %, for light having a wavelength selected from the visible wavelength range.
• the term “visible light” especially relates to light having a wavelength selected from the range of 380-780 nm.
• the transmission can be determined by providing light at a specific wavelength with a first intensity to the waveguide under perpendicular radiation and relating the intensity of the light at that wavelength measured after transmission through the material, to the first intensity of the light provided at that specific wavelength to the material (see also E-208 and E-406 of the CRC Handbook of Chemistry and Physics, 69th edition, 1088-1989).
• the waveguide plate may be colored, due to the presence of luminescent material (see also below).
• substantially may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially may also be removed. Where applicable, the term “substantially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%.
• the term “comprise” includes also embodiments wherein the term “comprises” means “consists of.
• the invention further applies to a device comprising one or more of the characterizing features described in the description and/or shown in the attached drawings.
• Figs. la- lb schematically depict basic embodiments according to the invention.
• Figs. 2a-2d schematically depict specific configuration of the converter device and light source(s);
• Figs. 3a-3i schematically depict a number of variants and options within the present concept.
• Fig. 1 schematically depicts a lighting device 1 which comprises (a) a light source 100, such as a solid state LED or laser diode, for producing light source light 110.
• a light source 100 such as a solid state LED or laser diode
• This may for instance be UV, violet or blue light, especially blue light.
• the light source 100 may also be a plurality of light sources (see examples below), which may produce light source light 110 having substantially the same wavelength distributions or having different wavelength distributions (such as UV and blue light).
• visible light is produced, such as blue light and/or one or more of green, yellow, orange and red light.
• the lighting device 1 further comprises (b) a transparent converter device 200.
• the converter device 200 is arranged downstream of the light source 100. This converter device 200 is especially configured for converting at least part of the light source light 110. For instance, blue light may be at least partially converted to one or more of green, yellow, orange and red light.
• the transparent converter device 200 When producing lighting device light, indicated with reference 11 , of white nature, and the light source light 110 being of blue nature, the transparent converter device 200, will convert part of the light source light 110 but also allow part of the light source light 110 transmit through the transparent converter device 200.
• the lighting device light 11 is shown at the downstream side of the converter device 200 (i.e. emanating from the front face).
• the transparent converter device 200 comprises a first polymer containing matrix 201 containing discrete particles 210.
• the discrete particles 210 are embedded in the first polymer containing matrix 201.
• the discrete particles 210 comprise a second polymer containing matrix 211 with luminescent material 212 dispersed therein.
• the luminescent material 212 is the converter, which absorb at least part of the light source light 110, and generated luminescent material light.
• Light 11 escaping from the converter device 200 comprises at least the light generated by the luminescent material 212, but may optionally also comprise light source light 110.
• the light source light 110 may be blue light and the luminescent material light might be yellow and red light. Together, white light as lighting device light 11 may be generated.
• the luminescent material 212 in the device 1 may be lit by LEDs behind the (flexible) configuration. For instance, a full array of LEDs can be used (see also below).
• the converter device 200 has a back face 232 and a front face 231, and in general an edge 233. The converter device 200 may be lit in a direction from the back face 232 to the front face 231. Optionally and/or additionally, the converter device 200 may be lit at the edge face 233 with the light source(s) 100.
• Figure lb schematically depicts in more detail the converter device 200.
• the discrete particles 210 are embedded in the first matrix 201.
• the particles 210 themselves comprise the second matrix material 211, with luminescent material 212 embedded therein.
• particulate luminescent material is depicted, but the luminescent material 212, for instance when comprising an organic dye, may also be molecularly dispersed in the second matrix 211.
• the first matrix 201 may comprise luminescent material (not depicted) (in addition to the second matrix 211 comprising luminescent material 212) such as inorganic luminescent material.
• FIGs. 2a-2d schematically depict specific configuration of the converter device and light source(s).
• Figure 2a depicts and embodiment wherein the converter device 200 is lit by light sources 100, especially LEDs, which are in a contact position.
• Figure 2b schematically depicts an embodiment wherein the light source(s) 100 are at least partially embedded in the converter device 200.
• the converter device 200 may comprise cavities, for instance in the back face 232.
• the converter device 200 is lit by one or more light sources 100, especially LEDs or laser diodes, which are at the edge(s) 233 of the converter device 200, a so-called edge-lit configuration.
• the light source(s) 100 are depicted to be in contact with the converter device 200, but are not necessarily configured in such a way (see by way of example also figure 2d).
• light may also be coupled from sides into a transparent wave guide (not shown) which can illuminate the converter device. In this configuration the converter device does not need to be in optical contact with the wave guide.
• the converter device 200 is lit by one or more light source(s) 100, especially LEDs or laser diodes, which are in a non-contact position.
• a configuration may be desirable in flexible luminaire systems.
• the converter device 200 may comprise one or more optical layers or optical items, such as reflective layers or mirrors, wavelength selective layers or mirrors, etc. For the sake of clarity, such layers or items have not been depicted.
• blue emitting LEDs are used.
• LEDs emitting at different wavelength(s) can be used as well.
• a reflector or reflector layer is arranged, configured to reflect luminescent material light and optionally light source light 110 in a direction from the back face 232, and lighting device light 11 emanates from the back face 232 of the lighting device 1.
• Figures 3a-3e (and 3g) schematically depict particles 210 having an elongated shape, i.e. having an aspect ratio larger than 1.
• Figures 3a-3e schematically depict embodiments wherein the converter device 200 is a layer with binder polymer, that has been cured or hardened. Binding polymer 240 forms a matrix to hold particles together. For instance, a liquid binder composition as polymer containing matrix, containing the discrete particles, may be applied to a substrate and hardened.
• Figures 3b-3e schematically depict a non- limiting number of different variants. Figure 3b is the same as figure 3a, whereas figure 3c schematically depicts an embodiment wherein the discrete particles 210 have different dimensions, here a plurality of different dimensions.
• Figure 3d schematically depicts an embodiment, wherein the discrete particles 210 comprise two subsets of particles, wherein within each subset, the discrete particles 210 substantially have the same dimensions.
• the particles 210 can have approximate same size (shape or thickness), different size, or two kind of sizes, etc.
• Figure 3e schematically depicts an embodiment with two layers 201, in fact two converter devices, which can be assembled in one integral converter device 200.
• more than two layers 201 may be applied.
• the layers 201 may be in physical contact with adjacent one or more neighboring layers, but may also be arranged at a non-zero distance.
• the luminescent materials in the different layers may optionally also differ.
• an upstream layer may comprise a luminescent material converting at least part of the light source light 110 into green light
• a downstream layer may comprise a luminescent material converting at least part of the light source light 110 and/or luminescent material light of the downstream layer luminescent material into red light.
• Figures 3a-3e schematically depict converter devices that look like binder based layers.
• the same principles with respect to aspect ratio, number of layers, may also apply to self-supporting bodies.
• the layer may comprise discrete particles 210 containing different luminescent materials 212.
• concentration of the luminescent material 212, especially when being organic luminescent material in the second polymer containing matrix 202 is typically between 0.00001 - 5 wt%.
• the particles such as flakes, may contain a combination of organic luminescent molecules.
• the concentration may range from lppm by weight up to 1 wt.% with respect to the second polymer containing matrix.
• the concentration can range from 1 wt.% to 50 wt.% with respect to the second polymer containing matrix.
• the concentration of the particles of the second polymer congaing matrix may be in to rage 1-90 wt.% in the first polymer containing matrix.
• the concentration to be used depends various parameters including layer thickness of the layer (or foil), and thickness and concentration of the discrete particles.
• organic luminescent materials include but are not limited to perylene derivatives such as Lumogen Red f305, Lumogen Orange f240, Lumogen Yellow f083 or Lumogen Yellow fl70 which can be purchased from BASF. They can also be quantum dots such as InP, CdSe, etc.
• the system mat also comprise nano or micron sized inorganic luminescent materials such as YAG:Ce, LuAG:Ce etc.
• the matrix material can be for example PMMA, PET, PEN, PC, etc.
• the first polymer matrix, especially when used as binder, can be for example an acrylate, epoxy, PVA, etc.
• the solvent can be water, but also other "friendly "solvents can be used such as ethanol, propanol, isopropanol, etc.
• Particles or binder may comprise a getter to improve the lifetime of the luminescent material.
• several layers are stacked on top of each other.
• the first polymer containing matrix preferably has a relatively low oxygen transmission rate, and can for example comprise the following polymer materials, with the oxygen transmission rate of the polymer material indicated between brackets: PVDC - poly vinylidene chloride (0.8 cm 3 /m 2 -day-bar), PVDF - poly vinylidene fluoride (0.8 cm 3 /m 2 -day-bar), EVOH - ethylene vinyl alcohol (0.5 cm 3 /m 2 -daybar), PBT - polybutylene terephthalate (5 cm 3 /m 2 -daybar), PEN - Poly ethyle naphthalate (8 cm 3 /m 2 -day-bar), PAN - Poly acrylo nitrile (9 cm 3 /m 2 -day-bar), PA6 - Nylon6 (10 cm 3 /m 2 -daybar) or PET - Poly ethylene terephthalate (20 cm 3 /m 2 -daybar).
• Figure 3f schematically depicts a flexible converter device 200.
• Figure 3g schematically depicts an embodiment of the discrete particle 210.
• the particle 210 has in this embodiment a length L and a width W, which leads to an aspect ratio L/W, which is here larger than 1.
• discrete particles 210 are for instance flakes.
• Discrete particles 210 such as flakes, can have a size preferably below 2 mm, more preferably below 0.5 mm, most preferably below 0.1 mm.
• Discrete particles 210, such as flakes can have random shaped or specific shapes such as squares, hexagons, triangles, etc.
• the thickness of the discrete particles 210, such as flakes is typically below 100 um, more preferred below lOum but is of course dependent on the size of the discrete particles 210, such as flakes.
• High aspect ratio discrete particles 210 such as flakes, can have aspect ratio preferable above 10, more preferably above 100.
• Luminescent polymer discrete particles 210 can be made using various production techniques including but not limited to milling, mechanical cutting, laser cutting, lithography, etc.
• FIG. 3h schematically depicts an alternative embodiment of the discrete particle 210.
• the discrete particle 210 comprises a second polymer containing matrix 211 with a luminescent material 212 dispersed therein.
• the discrete particle 210 further comprises a coating layer 213.
• the coating layer 213 preferably comprises a material that has a relatively low oxygen transmission rate and a relatively high transparency.
• the coating layer 213 comprises an inorganic material, for example - but not limited to - aluminum oxide or silicon dioxide.
• Aluminum oxide and silicon dioxide are materials that are highly transparent and have a relatively low oxygen transmission rate.
• the coating layer 213 may consist of a single layer of material or alternatively of a multilayer stack of, for example, two or more inorganic layers.
• the coating layer 213 reduces the transport of oxygen into the second polymer containing matrix 211 and the luminescent material 212.
• the luminescent material 212 comprises an organic luminescent material and/or quantum dot material which are relatively sensitive towards degradation due to oxygen
• the photo-chemical stability of the luminescent material 212 is improved due to the coating layer 213.
• the life time of the luminescent material 212 and therefore that of the discrete particle 210 is improved.
• lowering the oxygen concentration to a value below 0.1 vol. % in the polymer containing matrix 211 by applying a coating layer 213, may result in an improvement of the lifetime of the transparent discrete particle 210 by a factor 5 to 10.
• the coating layer 213 may be applied by means of chemical vapor deposition (CVD) or atomic layer deposition (ALD) processes. Both CVD and ALD processes can be run in a fluid bed reactor, for example.
• Figure 3i schematically depicts an alternative embodiment of a converter device 200 comprising a coating layer 215 for improving the life time of the converter device 200.
• the converter device 200 further comprises a first polymer containing matrix 201 containing discrete particles 210, as for example shown in figure 1 or figure 3f.
• the coating layer 215, like the coating layer 213, preferably comprises a material that has a relatively low oxygen transmission rate and a relatively high transparency.
• the coating layer 215 comprises an inorganic material, for example - but not limited to - aluminum oxide or silicon dioxide.
• Aluminum oxide and silicon dioxide are materials that are highly transparent and have a very low oxygen transmission rate.
• the coating layer 215 may consist of a single layer of material or alternatively of a multilayer stack of, for example, two or more inorganic layers.
• the coating layer 215 reduces the transport of oxygen into the second polymer containing matrix 211, increasing the life time of the luminescent material and hence that of the converter device 200.
• the discrete particles 210 may contain a coating layer as well, as shown in Figure 3h.
• Lumogen F Yellow 083 (BASF) was molecularly dissolved in 20 wt.% PMMA in di-chloromethane. 10 micron thickness films were processed by using a doctor blade. Subsequently, small particles / flakes of this material were produced by milling. Flakes were subsequently incorporated in a flexible matrix of PDMS Sylgard 184 (1 :10 ratio cross-linker). Next, the mixture was poured onto a flat surface and cured at 60 degrees

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