Leds with recycled phosphor

Abstract

The invention provides a light generating device (100) comprising (i) a solid state light source (10) and (ii) a luminescent material element (200); wherein the solid state light source (10) is configured to generate light source light (11), wherein the luminescent material element (200) is configured to convert at least part of the light source light (11) into luminescent material light (201); wherein the light generating device (100) is configured to generate device light (101) comprising luminescent material light (201) and light source light (11) and having a color rendering index of at least 65; wherein the luminescent material element (200) comprises n1 first luminescent materials (210) being configured to emit luminescent material light having a centroid wavelength in the 440-590 nm wavelength range, and n2 second luminescent materials (220) being configured to emit luminescent material light having a centroid wavelength in the 590-780 nm wavelength range, wherein n1≥3, n2≥0, and (n1+n2)≥5.

Description

[0001] LEDs with recycled phosphor

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a light generating device comprising recycled phosphors, a lighting device comprising the light generating device, and a method for providing such device.

[0004] BACKGROUND OF THE INVENTION

[0005] Light generating devices comprising recycled phosphors are known in the art. For instance, EPl 138741 A2 describes a method of recycling fluorescent substance for a fluorescent lamp, a recycled fluorescent lamp and a lighting apparatus using thereof. The fluorescent substance material and the glass material are individually recovered by classifying the recovered fluorescent lamps according to kind or quality and by stripping off the fluorescent substance coating from the inner surface of the glass bulbs. The recovered fluorescent substance material and the glass material are regenerated and reused. In this case, in the process for regenerating the recovered fluorescent substance, mercury involved in the recovered fluorescent substance is removed, for example, by firing the recovered fluorescent substance in a vacuum, in an inert atmosphere. The recovered glass material is also carried out the process for removing mercury.

[0006] SUMMARY OF THE INVENTION

[0007] LED phosphors contain rare-earth and other critical metals such as Ga, and therefore it is of interest to recycle the phosphors from waste LEDs (Light Emitting Diodes). Although recycling may appear not commercially viable today, it might be in the future as it will be (financially) encouraged increasingly by governmental bodies. It could even become mandatory at some point in time. For instance, the EU Critical Raw Materials Act is a forward-looking legislative proposal that aims to secure the supply of critical raw materials needed in the EU; this includes a recycling target of 15%. Recycling of the critical materials in phosphors might be done at various levels: entire LEDs could be reused as they can be harvested by e.g., desoldering waste LEDs from the PCB by heating, and the majority of LEDs in wasted LED lamps and luminaires is still functioning. An alternative method to harvest wasted LEDs may be electrohydraulic fragmentation. However, the wide variety of LED package types and CCTs (i.e., Correlated Color Temperatures) and CRIs (Color Rendering Indexes) of the LEDs may make it difficult to reuse them. Alternatively, the phosphor material can be extracted on particle level from the LED package by a chemical process. The (silicone) encapsulant surrounding the phosphor particles may for instance be dissolved using an organic agent. The result may be a phosphor mixture (at least in the case of white LEDs). Measurement have shown that samples of recycled phosphor mixtures may still show a quantum efficiency of 90-96%, indicating that the extracted phosphors are not significantly damaged by this chemical separation process. However, separation of the individual phosphors from these mixtures whilst maintaining the phosphor properties seems too complex or even not feasible as the differences in e.g., particle size and density may be too small to allow physical separation. On the other hand, chemical separation down to the individual chemical element level may be feasible but may be a lengthy and costly operation. It, therefore, appears most attractive to recycle LED phosphors on the level of the phosphor mixture.

[0008] It further appears that a phosphor mixture obtained by extraction from waste LEDs cannot directly be applied in new LEDs, because the phosphor composition needed normally may vary with LED specs such as color temperature and color rendering index. Even if the harvesting of phosphor from waste LEDs would be done per correlated color temperature / color rendering index combination (or “CCT-CRI combination”), the obtained phosphor mixture may normally not be used directly, because the final CCT-CRI may also depend on configuration of the light generating device, for instance on the (wavelength of the) solid state light source, the package type, and the method of phosphor application (e.g. sedimented or not). This is because, different from low-pressure-Hg-discharge lamps, the (especially blue) light from the solid state light source (also indicated as “chip”) may contribute to the spectrum emitted by the device and the extent of conversion by the phosphor may require precise tuning. Moreover, in embodiments green phosphor emission may partly be absorbed by a red phosphor. The amount of conversion as well as absorption of e.g., emission of the green phosphor may depend on the package and phosphor geometry.

[0009] Hence, it is an aspect of the invention to provide an alternative light generating device (comprising (recycled) luminescent material), which preferably further at least partly obviates one or more of above-described drawbacks. It is a further aspect of the invention to provide a method to provide a luminescent material element (comprising (recycled) luminescent material), which preferably further at least partly obviates one or more of above- described drawbacks. The present invention may have as object to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

[0010] According to a first aspect, the invention provides a light generating device. The light generating device especially comprises (i) a solid state light source configured to generate light source light. The light generating device further especially comprises a luminescent material element. The luminescent material element may in embodiments comprise luminescent material, especially comprising a number of (different) luminescent materials. In embodiments, the luminescent material comprises recycled luminescent material(s). In further embodiments, the luminescent material comprises (a combination of) recycled luminescent material and non-recycled luminescent material. Hence, in specific embodiments the luminescent material element comprises recycled luminescent material (and especially (also) non-recycled luminescent material). In specific embodiments, the solid state light source is configured to generate blue light source light. In further embodiments, the solid light source is configured to generate violet-light. In further specific embodiments, the solid light source may be configured to generate UV-light. The light source light may especially comprise blue light source light and / or violet light source light, even more especially blue light source light. Further, especially, the luminescent material element is configured to convert at least part of the light source light into luminescent material light. The device light especially comprises (at least) luminescent material light. In specific embodiments, the light generating device is configured to generate device light comprising luminescent material light and light source light. The device light may in embodiments have a color rendering index (“CRI”) of at least 65, and in further embodiments especially a CRI of at least 70. The device light may in embodiments comprise white light. Further, especially the luminescent material comprises one or more first luminescent materials in embodiments and optionally one or more second luminescent materials. The one or more first luminescent materials are (each) in embodiments configured for emitting (luminescent material) light having a (first) centroid wavelength in the 440-590 nm wavelength range, such as having a centroid wavelength in the 490-590 nm wavelength range. In specific embodiments, the first luminescent material(s) may be configured to emit (luminescent material light comprising) green light and / or yellow light. Further, in embodiments, the second luminescent material(s) (if present) may be configured to emit (luminescent material) light having (second) a centroid wavelength in the 590-780 nm wavelength range. In embodiments, a difference between the first centroid wavelength and the second centroid wavelength is at least 5 nm, especially at least 10 nm. In further specific embodiments, the optional second luminescent material(s) may be configured to emit red (luminescent material) light. Additionally, or alternatively, the optional second luminescent materials may be configured to emit orange (luminescent material) light. Further, especially, any one of the first luminescent materials may in embodiments comprise a recycled luminescent material or a non-recycled luminescent material (or both). Likewise, any one of the second luminescent materials (if present) may comprise a recycled luminescent material or a non-recycled luminescent material (or both). In embodiments, the luminescent material element comprises nl (different) first luminescent materials. In specific embodiments, the luminescent material element comprises at least two first luminescent materials. In further embodiments, the luminescent material element comprises at least three first luminescent materials. In specific embodiments nl equals 1. In further specific embodiments, the luminescent material element further comprises n2 (different) second luminescent materials. In embodiments, the luminescent material element may comprise first luminescent materials but no second luminescent material(s). In embodiments, n2 may be zero. In further embodiments, the luminescent material element may comprise at least 1 second luminescent material. Further, especially a total (nl) of (different) first luminescent materials plus a total (n2) of (different) second luminescent materials is in embodiments equal to or larger than 5. Hence, in specific embodiments nl>2, especially nl>3; n2>0; and (nl+n2)>5.

[0011] Hence, in embodiments, the invention provides a light generating device comprising (i) a solid state light source and (ii) a luminescent material element (especially in embodiments comprising recycled luminescent material and non-recycled luminescent material); wherein the solid state light source is configured to generate light source light, wherein the luminescent material element is configured to convert at least part of the light source light into luminescent material light; wherein the light generating device is configured to generate device light comprising luminescent material light and light source light and having a color rendering index of at least 65; wherein the luminescent material element comprises nl first luminescent materials (each) being configured to emit luminescence material light having a centroid wavelength in the 440-590 nm wavelength range, and n2 second luminescent material(s) (each) being configured to emit luminescent material light having a centroid wavelength in the 590-780 nm wavelength range, especially wherein nl>3, n2>0, and (nl+n2)>5.

[0012] With such light generating device, light may be generated with a desired (especially white) spectrum using at least recycled luminescent material, especially wherein a total of the luminescent material (in the luminescent material element) comprises a higher volume percentage (vol%) of recycled luminescent material than non-recycled (or “pristine”) luminescent material. The amount of pristine phosphor relative to a total amount of the luminescent materials in the luminescent material element may especially be less than 50 vol%, and in embodiments less than 25 vol%, such as in the range of 5-25vol%, especially if the recycled luminescent material comes from a wide mix of used luminescent materials (from e.g., a wide range of waste LEDs). The amount of pristine luminescent material may optionally be reduced. The amount of non-recycled luminescent material may in embodiments be 10 vol% at maximum (of a total amount of the luminescent material in the luminescent material element) (for instance, if the harvesting of recycled luminescent material is done per CCT-CRI combination). By carefully selecting the pristine luminescent material to be added to the recycled luminescent material based on among others the characteristics of the recycled luminescent material, the light may be generated with a desired correlated color temperature and color rendering index.

[0013] Selecting (the amount and characteristics of) the pristine luminescent material may be based on measuring a spectrum of at least one LED configured with only the recycled luminescent material, especially wherein the luminescent material does not provide enough conversion to reach the desired target color point. For a white LED this may for instance imply that an amount of recycled luminescent material is used to provide a spectrum with chromaticity below (and preferably near) the black body locus. The recycled luminescent material may be mixed with a host material such as silicone and may be cured before measuring the spectrum of the LED. Based on this spectrum it can be calculated what phosphor (luminescent material) needs to be added to reach the target color point and color quality. If possible, this added amount of phosphor may comprise (partly) recycled luminescent material. Yet, the added phosphor will especially comprise at least pristine luminescent material. In specific embodiments, the added (amount of) phosphor comprises essentially only non-recycled luminescent material. The added phosphor may be added, such as in an extra layer, to the LEDs (already comprising the recycled luminescent material). Alternatively, pristine luminescent material and recycled luminescent material may be mixed (according to the predetermined amounts), and LEDs may be build using the mixture of recycled and pristine luminescent material (see further below).

[0014] This invention solves the problem that the phosphor mixture obtained by extraction from waste LEDs cannot be applied directly in new LEDs. Based on analysis of the emission spectrum of the luminescent material mix obtained from the recycled LEDs, a broad variation of LED spectra with various CCT and CRI may be provided by the addition of predetermined amounts of specific virgin phosphor material.

[0015] As indicated above, the light generating device may in embodiments comprise (a combination of) recycled luminescent material(s) and non-recycled luminescent material(s). The term “non-recycled luminescent material” may refer to a virgin luminescent material (i.e., not used before in a luminescent material element). The term “virgin” may also be indicated with “fresh” or “pristine”, such as e.g., in phrases like “pristine luminescent material” and “fresh luminescent material”. The term “recycled luminescent material(s)” may in embodiments relate to a mix of (recycled) luminescent materials. The term “recycled” in combination with a material may indicate that the material has been used before (such as in a product comprising the material) and may have been put through a process, e.g., an extraction process, so it can be used again. Both, the prior use as well as the process may affect specific properties of the recycled material. For instance, the recycled luminescent material may be attached to some matrix material (see below), Further, properties of such matrix material may have altered in time. The recycled luminescent materials may for instance be harvested / extracted from LEDs that have been used before, or, e.g., obtained from rejected LED material (such as LEDs that do not correspond to the required specifications). This way used luminescent material may be re-used, see also further below.

[0016] The term “light generating device” may herein especially relate to a “light generating device with recycled luminescent material”. It may especially relate to a solid state light source with luminescent material configured on the die, especially luminescent material (at least partly) embedded in a (light transparent) polymeric material.

[0017] The recycled luminescent materials are in embodiments (selected) from luminescent materials originating from light emitting diodes (“LEDs”). The recycled luminescent materials may in embodiments originate from white light emitting LEDs. In embodiments, the device light (generated by the light generating device as defined herein) may (also) especially comprise white light. The solid state light source may in embodiments be configured for generating one or more of blue light and violet light, more especially for generating blue light.

[0018] The term “white light”, and similar terms, herein, is known to the person skilled in the art. It may especially relate to light having a correlated color temperature (CCT) between about 1800 K and 20000 K, such as between 2000 and 20000 K, especially 2700- 20000 K, for general lighting especially in the range of about 2000-7000 K, such as in the range of 2700 K and 6500 K. Yet further, in embodiments the correlated color temperature (CCT) is especially within about 15 SDCM (standard deviation of color matching) from the BBL (black body locus), especially within about 10 SDCM from the BBL, even more especially within about 5 SDCM from the BBL.

[0019] The term “centroid wavelength”, also indicated as c, is known in the art, and refers to the wavelength value where half of the light energy is at shorter and half the energy is at longer wavelengths; the value is stated in nanometers (nm). It is the wavelength that divides the integral of a spectral power distribution into two equal parts as expressed by the formula Ac = X I(k) / (S I( A)), where the summation is over the wavelength range of interest, and I (A) is the spectral energy density (i.e. the integration of the product of the wavelength and the intensity over the emission band normalized to the integrated intensity). The centroid wavelength may e.g., be determined at operation conditions.

[0020] The term “blue light” may especially relate to light having a wavelength in the range of about 440-490 nm. The terms “violet light” or “violet emission” especially relates to light having a wavelength in the range of about 380-440 nm. Herein, UV may especially refer to a wavelength selected from the range of 190-380 nm, such as 200-380 nm.

[0021] In embodiments, the recycled luminescent materials may at least comprise a green luminescent material (or green “phosphor”). In further embodiments, the recycled luminescent materials may (also) comprise a yellow luminescent material (yellow phosphor). Yet, the recycled luminescent materials may in embodiments comprise a green luminescent material and a yellow luminescent material. Hence, the first luminescent material(s) may in embodiments comprise a recycled green phosphor and / or a recycled yellow phosphor. The first luminescent material(s) may further comprise a pristine phosphor (which may for instance also be a green luminescent material) to configure the luminescent material light according to the desired specification.

[0022] Herein, a color indication in combination with a luminescent material especially refers to a luminescent material that is configured to emit the respective color upon excitation. For instance, a green luminescent material / green phosphor is especially configured to emit green light (when being exited).

[0023] The term “green light” may especially relate to light having a wavelength in the range of about 490-560 nm. The term “yellow light” may especially relate to light having a wavelength in the range of about 560-590 nm. The terms “orange light” may especially relate to light having a wavelength in the range of about 590-620 nm. The term “red light” may especially relate to light having a wavelength in the range of about 620-750 nm. The phrase “light having one or more wavelengths in a wavelength range” and similar phrases may especially indicate that the indicated light (or radiation) has a spectral power distribution with at least intensity or intensities at these one or more wavelengths in the indicate wavelength range. For instance, a blue emitting solid state light source will have a spectral power distribution with intensities at one or more wavelengths in the 440-490 nm wavelength range.

[0024] The luminescent material(s) may in embodiments comprise two “classes” of luminescent materials having centroid wavelength in different ranges, i.e., the first luminescent materials, especially having a centroid wavelength in the 440-590 nm wavelength range, and the second luminescent materials (if present), especially having a centroid wavelength in the 590-780 nm wavelength range. Essentially, applying (only) first luminescent materials in the luminescent material element may allow providing white light source light. Especially at least part of the luminescent material(s) may comprise first luminescent material(s). The luminescent material element not necessarily comprises any second luminescent material. Yet, in embodiments, the second luminescent material may be applied to further define the emission spectrum of light generating device. Applying the second luminescent material in the luminescent material element may provide “warmer” light source light (having a lower CCT). The second luminescent material may in embodiments comprise non-recycled luminescent material (only). In embodiments, the recycled luminescent material(s) may comprise first luminescent material(s) as well as second luminescent material(s).

[0025] In specific embodiments, the nl first luminescent materials may comprise two recycled luminescent materials and a single non-recycled luminescent material. The recycled luminescent material may especially originate from (be extracted from) a mix of several types of LEDs. Hence, in other embodiments, the nl first luminescent materials may comprise three, four, or even more recycled luminescent materials (and optionally one or two or even more non-recycled luminescent materials). As will be understood, many combinations of (recycled and non-recycled) first luminescent materials are feasible. In further embodiments, the nl first luminescent materials may for instance comprise only recycled luminescent materials and no non-recycled luminescent materials. Hence, in embodiments, nl may be three, four, or five. In further embodiments nl may be six, or at least seven, such as ten or more. Furthermore, in specific embodiments, the luminescent material element may lack any second luminescent material. However, in further embodiments, the n2 second luminescent materials may (only) comprise a single nonrecycled luminescent material. Yet, in further embodiments, the n2 second luminescent materials may comprise two or more, especially two, non-recycled luminescent materials. The n2 second luminescent materials may in further embodiments (also) comprise one or more recycled second luminescent materials. In specific embodiments, the luminescent materials may comprise non-recycled second luminescent materials, and may lack nonrecycled first luminescent materials. Hence, in embodiments, n2 may be equal or larger than one, such as equal or larger than two, such as three, or four, or even five or more. Hence, in further specific embodiments nl>4 and n2>2. In further embodiments, nl >2 and n2 >4. Hence, in embodiments nl >n2. In alternative embodiments nl<n2. The luminescent material element may in embodiments comprise at least six luminescent materials.

[0026] A total of nl first luminescent materials and n2 second luminescent materials may in embodiments comprise at least one recycled luminescent material, such as especially at least two recycled luminescent materials, even more especially at least three recycled luminescent materials. In embodiments, a total number of different recycled second luminescent materials may be lower than a total number of different recycled first luminescent materials in the luminescent material element. The luminescent material element may in embodiment for instance comprise one or two (or even zero) different recycled second luminescent materials and two, three, or even more different recycled first luminescent materials. Yet, in other embodiments, a total number of different recycled first luminescent materials may be lower than a total number of different recycled second luminescent materials in the luminescent material element. The number of different recycled first luminescent materials in the luminescent material element may for instance be one or two, whereas the number of (different) recycled second luminescent materials may be more than two, such as three, four, five, or more in embodiments. In specific embodiments at least the first luminescent material comprises one or more recycled luminescent materials. In further embodiments, at least one of the first luminescent materials comprises recycled luminescent material and at least one of the second luminescent materials comprises a recycled luminescent material. Moreover, the term “luminescent material” such as in phrases like “(non-) recycled luminescent material”, and “first luminescent material” may refer to a plurality of (different) luminescent materials. It is noted that herein the term “nl first luminescent materials” especially refers to nl different first luminescent materials, wherein nl (is an integer and) may optionally be zero or one. Likewise, the term “n2 second luminescent materials” especially refers to n2 different second luminescent materials, wherein n2 (is an integer and) may be zero or one. Note that the general term “luminescent material” may refer to both the first luminescent material and the second luminescent material. Likewise, the general term “luminescent material” as well as the terms “first luminescent material(s) and “second luminescent material(s)” may apply for both the recycled luminescent material and the nonrecycled luminescent material.

[0027] The general term “luminescent material” may especially refer to a material that can convert first radiation, especially one or more of UV radiation, violet radiation, and blue radiation, into second radiation. The luminescent materials described herein may (during use) at least partly convert light source light generated by the solid state light source (e.g., blue light, violet light, or UV-light) into a second radiation (for instance comprising yellow light). The luminescent material light especially comprises the second radiation. In general, the first radiation and second radiation have different spectral power distributions. Hence, instead of the term “luminescent material”, also the terms “luminescent converter” or “converter” may be applied. In embodiments, the “luminescent material” may especially refer to a material that can convert radiation into e.g., visible and / or infrared light. For instance, in embodiments the luminescent material may be able to convert one or more of violet radiation and blue radiation, into visible light. Hence, upon excitation with radiation, the luminescent material emits radiation. In embodiments, the term “luminescence” may refer to phosphorescence. In embodiments, the term “luminescence” may also refer to fluorescence. Instead of the term “luminescence”, also the term “luminescent material light” or “emission” may be applied. Hence, the terms “first radiation” and “second radiation” may refer to excitation radiation and emission (radiation), respectively. Likewise, the term “luminescent material” may in embodiments refer to phosphorescence and / or fluorescence. The term “luminescent material” may also refer to a plurality of different luminescent materials. Hence, the term “luminescent material” may in specific embodiments also refer to a luminescent material composition. The luminescent material may comprise a luminescent particle. The luminescent particle may be embedded in a further material in the luminescent material, e.g., in an especially transparent host material. Instead of the term “luminescent material” also the term “phosphor” may be applied. These terms are known to the person skilled in the art. The luminescent material, especially the recycled luminescent material, may refer to a composition of a luminescent material (especially a luminescent particle) and a host material.

[0028] During use of the light generating device, a part of the light source light may be transmitted without a conversion and another part of the first radiation may undergo a conversion to the luminescent material light. Hence, the resulting radiation may be a combination of the light source light and luminescent material light.

[0029] The (different) (first and / or second) luminescent materials especially have distinctive characteristics or properties distinguishing them from each other. The (different) first luminescent materials may in embodiments for instance relate to phosphors emitting a different spectrum, such as a green light emitting phosphor and a yellow light emitting phosphor. Likewise, different second luminescent materials may relate to a phosphor emitting e.g., red light and a phosphor emitting orange light. Moreover, in embodiments, one luminescent material may emit a broad spectrum, whereas another luminescent material may emit a narrow spectrum. Hence, luminescent materials having centroid wavelengths of their luminescent material light differing at least 5 nm, such as at least 10 nm, may be indicated as (different) luminescent materials. Moreover, luminescent materials having the centroid wavelength of their luminescent material lights substantially the same, may be considered different if the spectral power distributions of the respective luminescent material lights differ. For instance, luminescent materials having intensities of their spectral power distribution at the same wavelengths but intensities of differing at least 2%, such as at least 5%, especially at least 10% in spectral power may be considered different luminescent materials (even when the centroid wavelengths of the emissions and / or a total of the spectral power over the emission band could be substantially the same).

[0030] The distinguishing characteristic may further e.g., be based on the types of phosphor material. For instance, one of the luminescent materials may comprise a garnet and another (first) luminescent material may be a nitride. Additionally, or alternatively one of the (second) luminescent materials may comprise a (manganese doped) K^SiFe (or “KSF”) and / or a (europium doped)) CaAlSiNs comprising material. The first luminescent material especially comprises a garnet. Hence, luminescent materials, even having identical chemical formulas with exception of the luminescent species, may be considered different luminescent materials. Hence, YsAbO^Ce and YsAhOn r are considered different luminescent materials.

[0031] Yet a further example of how the luminescent materials may differ in characteristics is by comprising a different composition. For instance, one of the first luminescent materials may comprise or be a garnet of the type YsAbO^Ce, and another first material may comprise or be a garnet of the type LusAhOn Ce. Hence, luminescent materials having different chemical formulas may be considered different luminescent materials (even when the centroid wavelengths of the emissions could be essentially the same (see also above)). The term “different" in phrases like “different luminescent materials” and, e.g., “different phosphors” may thus (also) refer to the same crystallographic type of luminescent materials, such YsALOn Ce, YsAhOn r and LusAhOn Ce (being considered as different luminescent materials).

[0032] Further, the distinguishing characteristic may also be a luminescent species or dopant concentration. Especially when the dopant concentration differs substantially, like at least 10 %, like at least 20%, such as at least 50%, the luminescent materials may be considered different luminescent materials. For instance, YsALOn Ce with 1 mol% Ce and YsAhOn Ce with 1.5 mol% Ce may be considered different luminescent materials, as the latter has 50% more dopant than the former.

[0033] In embodiments, luminescent materials may be selected from garnets and nitrides, especially doped with trivalent cerium or divalent europium, respectively. The term “nitride” may also refer to oxynitride or nitridosilicate, etc. Alternatively or additionally, the luminescent material(s) may be selected from silicates, especially doped with divalent europium. Yet, alternatively, or additionally, the luminescent materials may be selected from tetravalent doped manganese luminescent materials, like of the K2SiFe:Mn type.

[0034] The luminescent materials may in embodiments comprise a cerium doped garnet type material, such as cerium doped yttrium aluminum garnet (“YAG”). The luminescent material may further be a lutetium (aluminum) garnet (“LuAG” or “Lu-YAG”) or a gallium comprising garnet (“GaYAG”). In specific embodiments the first luminescent material comprises a luminescent material of the type AsBsOn Ce, wherein A in embodiments comprises one or more of Y, La, Gd, Tb and Lu, especially (at least) one or more of Y, Gd, Tb and Lu, and wherein B in embodiments comprises one or more of Al, Ga, In and Sc. Especially, A may comprise one or more of Y, Gd and Lu, such as especially one or more of Y and Lu. Especially, B may comprise one or more of Al and Ga, more especially at least Al, such as essentially entirely Al.

[0035] As indicated above, one of the luminescent materials may be a recycled luminescent material whereas another one may be a pristine luminescent material. In embodiments at least one of the non-recycled luminescent material(s) and one of the recycled luminescent materials are the same (type of) luminescent materials. In further embodiments, one or more of the non-recycled luminescent materials has the same characteristics or properties as a respective recycled luminescent material. Hence, in embodiments, one or more of the (different - first and / or second) non-recycled luminescent materials may also be present in the luminescent material element in the form of a recycled (first and / or second) luminescent material. Moreover, in embodiments, all different non-recycled luminescent materials that are comprised by the luminescent material element may also be comprised as recycled luminescent materials. In alternative embodiments, all recycled luminescent materials differ from the non-recycled luminescent materials in the luminescent material element.

[0036] It will be understood that different luminescent materials may be distinguished based on characteristics or properties known to the skilled person. Moreover, different luminescent materials may especially be distinguished based on a combination of several distinguishing characteristics / properties described above and / or known to the skilled person.

[0037] As indicated above, the recycled luminescent material may originate from used luminescent material, for instance from used LEDs. The used luminescent material may especially comprise luminescent material, especially phosphor particles, at least partly embedded in a host or matrix material. When harvesting / extracting the recycled luminescent material still some of the (used) host material may be attached to the recycled luminescent material. Some of the used host material may be bound to the phosphor particles. In embodiments, the phosphor particles may at least partly be embedded in the used host material (in the recycled luminescent material). The harvested material, optionally including used / recycled host material, may especially be shaped like particulate material, especially comprising particles. It may therefore herein also be indicated that “recycled luminescent material particles”, “particulate recycled luminescent material”, and comparable terms, comprise (particles of) luminescent material(s) (and host material attached to the particles of luminescent material(s)). The term “recycled luminescent material(s)” may refer to the phosphor(s) in the particulate recycled luminescent material. The particles of the particulate recycled luminescent material may in embodiments have a larger average volume that that of the phosphor particles and e.g. particles of non-recycled luminescent material(s) (i.e. pristine phosphor particles).

[0038] In embodiments, the recycled luminescent material may comprise clusters of phosphor particles. The recycled luminescent material particles may in embodiments comprise particles comprising (clusters of) phosphor particles. The particles may further especially comprise remaining (used) host material. The phosphor particles in the recycled luminescent material (particles) may in embodiments at least party be embedded in a (use / remaining) matrix / host material (i.e., matrix material of for instance the recycled LED). The particles comprising recycled luminescent material may in embodiments comprise (clusters of) a single type of phosphor particles (a single type of luminescent material) (especially also including used matrix material). Yet, in further embodiments, the particles comprising the recycled luminescent material may comprise a (cluster of a) plurality of different luminescent material. In yet further embodiments, the (recycled luminescent material) particle may comprise a (cluster of a) single luminescent material. The (clusters of a) single luminescent material may especially comprise (a) phosphor particle(s) (and used matrix material). Since the phosphors (luminescent materials) may be in the form of particles, it is herein described that the particles of recycled luminescent material may comprise clusters of particles of the luminescent materials (or clusters of phosphor particles). Moreover, the recycled luminescent material may be part of recycled luminescent material particles (especially comprising (clusters of) particles of the luminescent materials). In embodiments, each recycled luminescent material particle may originate from a single LED. Any recycled luminescent material particle may in embodiments especially comprise one, two, or three different (recycled) luminescent materials.

[0039] The (recycled) luminescent material(s) may in embodiments be present in (one or more) subregions of the luminescent material element. The subregions may be defined by (a) recycled luminescent material particle(s). The presence of remaining matrix material (from the original luminescent material (element) may result in a formation of subregions comprising recycled luminescent material (s) (plus remaining matrix material).

[0040] In embodiments, recycled luminescent material particles may be mixed with pristine luminescent material particles and successfully this mixture may be used to configure the luminescent material element, especially the light generating device. In embodiments of the luminescent material element obtained this way, the luminescent material element may comprise subregions comprising the recycled luminescent material(s). The subregions may further comprise remaining matrix material (also indicated as “second main host material”, see further below).

[0041] In embodiments, the (particles of) recycled luminescent material may be configured in a first layer wherein the pristine luminescent material is configured in a further layer. In such embodiments, especially the first layer may comprise a plurality of subregions.

[0042] The subregions may comprise one or more recycled (different) luminescent materials (especially luminescent particles at least partly embedded in a matrix). The subregion may in specific embodiments, comprise at least one luminescent material particle (and remaining matrix material). In Further embodiments, the subregion may comprise at least a singly type of luminescent materials. In specific embodiments, the subregions may comprise one or more of the first luminescent materials. In embodiments, the subregions may (also) comprise at least one second luminescent material (if present). Moreover, each subregion may in embodiments comprise a selection (a number kl) of luminescent materials selected from the (nl) first luminescent materials and the (n2) second luminescent materials (if present). The selection of luminescent materials selected from the nl first luminescent materials and the n2 second luminescent materials (if present) may in embodiments comprise a single (type of) luminescent material. In further embodiments, the selection may comprise at least two (different) luminescent materials. Each subregion may in further embodiments comprise (clusters of) at least two (recycled) luminescent materials, such as three or more (recycled) luminescent materials. In further embodiments, each subregion may comprise (clusters of) five different (recycled) luminescent materials at maximum, such as least four (recycled) luminescent materials at maximum. Each subregion may in embodiments especially comprise (clusters of) one to five different (recycled) luminescent materials, especially two to four different (recycled) luminescent materials, and in specific embodiments one to three different (recycled) luminescent materials, such as two to three different (recycled) luminescent materials. One or more of the subregions may in embodiments comprise three recycled luminescent materials. The subregion may for instance comprise two (recycled) first luminescent materials plus one (recycled) second luminescent material. However, one or more of the subregions may in embodiments comprise a single type of recycled luminescent material. One or more subregions may in embodiments especially comprise only one (different) garnet type of phosphor. For instance in embodiments, one or more of the subregions comprise luminescent materials selected from the nl first luminescent materials, wherein (only) one of luminescent materials is selected from the group of luminescent materials of the types AsEEOn Ce, wherein A comprises one or more of Y, La, Gd, Tb and Lu, and wherein B comprises one or more of Al, Ga, In and Sc.

[0043] Hence, in embodiments, the luminescent material element comprises subregions, wherein at least one of the subregions comprises one or more clusters of luminescent material(s), especially of one or more (optionally different types of) phosphor particles. A subregion may in embodiments comprise a single cluster of luminescent materials. In further embodiments, the subregion may comprise a plurality of clusters of luminescent material(s). In embodiments, a cluster may define a subregion. A subregion may in specific embodiments comprise one or more (smaller) (sub-)subregions, see also further below. Furthermore, a plurality of clusters of luminescent materials may define a (larger) cluster of luminescent materials. In embodiments, especially recycled luminescent material particles may be present in clusters comprising the recycled luminescent material and matrix material (especially second main host material, see below). The non-recycled luminescent material particles may especially not be present in clusters comprising the non-recycled luminescent material and second main host material, also see further below. The non recycled luminescent material may further in embodiments especially not define a subregion (comprising one or more clusters of luminescent materials).

[0044] The luminescent material element may have a (first) volume, and especially a portion of the (first) volume may comprise subregions. Further, (each of) the subregions may have a second volume. The second volume may depend on the method used to harvest / extract the recycled luminescent material and for instance the luminescent material in the second volume. In embodiments, e.g., particulate recycled luminescent material may be sifted in grades, and e.g., one or more grades may be applied in the luminescent material element. In further embodiments, e.g., an (additional) amount of remaining matrix material may have been removed in a solvent which may affect the second volume. Furthermore various luminescent materials may have a different shape and volume that may affect the second volume. A second volume (of a subregion) may in embodiments be at least 500 pm3, such as at least 1000 pm3, especially at least 5000 pm3, even more especially at least 10,000 pm3, and in embodiments at least 50,000 pm3. The second volume may further especially be equal to or less than 250,000 pm3, such as equal to or less than 100,000 pm3, and in embodiments equal to or less than 50,000 pm3.

[0045] Hence, in embodiments, the luminescent material element has a first volume (VI), wherein the luminescent material element comprises subregions within the first volume (VI), with each subregion comprising a selection of kl luminescent materials selected from the nl first luminescent materials and the n2 second luminescent materials, wherein l<kl<(nl+n2), especially wherein each subregion has a second volume (V2). In specific embodiments at least one of the subregions, especially any one of the subregions regions may comprise three (different) luminescent materials at maximum (kl<3). In embodiments different subregions may comprise different luminescent materials. For instance at least one subregion may comprise a first one of the kl luminescent materials and in embodiments a further subregions may comprise (at least) a second one of the kl luminescent materials. In embodiments, the first volume VI may be equal to a total volume of the luminescent material element. In specific embodiments, the (respective) second volumes (V2) (of the subregions) may be at least 5000 pm3. Hence, the luminescent material element may comprise recycled luminescent material. The subregions may in embodiments comprise at least 70 vol% of (a total of) the recycled luminescent material (present in the luminescent material element), such as at least 80 vol% of the recycled luminescent material, or even at least 90 vol% of the recycled luminescent material The subregions may in embodiments comprise substantially 100 vol% of (a total of) the recycled luminescent material (in the luminescent material element), especially up to 95 vol% of the recycled luminescent material at maximum, such as up to 90 vol% of the recycled luminescent material at maximum. The subregions may in embodiments comprise 50-100 vol% of a total of the recycled luminescent material, especially 60-100 vol% of the total of the recycled luminescent material, even more especially 70-95 vol% of the total of the recycled luminescent material, 50-90 vol% of the total of the recycled luminescent material. These volume percentages especially refer to a (total) volume of (one or more of) the recycled luminescent material(s) in (all of) the subregions relative to a (total) volume of the (respective) recycled luminescent material(s) in the luminescent material element. A total volume of the total luminescent material element may in embodiments be equal to the first volume. Said first volume especially includes a total volume of the subregions, especially being equal to a summation of the second volumes of all of the subregions. Hence, in embodiments 70 to 100 vol% of the recycled luminescent material(s) is present in the subregions and the remainder (up to 30 vol%) may be present in the first volume, and not in the subregions. In embodiments, substantially all of the recycled luminescent material(s) is (are) comprised in the subregions. A (average) concentration of the recycled luminescent material(s) may in embodiments be (substantially) larger in the subregions than in the first volume. It is noted that for individual subregions this may not be true since some of the recycled luminescent materials may be present only in a selection of the second volumes.

[0046] At least one of the kl luminescent materials may in embodiments especially substantially only be comprised in one or more of the subregions. This may, e.g., be true if said one of the kl luminescent materials is only present in the form of recycled luminescent material and not in the form of non-recycled luminescent material. Furthermore, the first volume may encompass all of the subregions. The first volume may especially be larger than a summation of the second volume (over all of the subregions). Hence, in specific embodiments an average (first) volume fraction (Voh v / v) of at least one of the kl luminescent materials in the first volume is smaller than a (second) volume fraction (Voh v / v) of the at least one of the kl luminescent material in a total of the second volume (i.e., Voh / Voh>l). Herein, Voli is especially defined as a ratio of a total volume of the at least one kl luminescent materials present in the first volume to the first volume; and Voh is defined as a total volume of the at least one kl luminescent materials present in the subregions to the total volume of the subregions (a summation of all (individual) V2 volumes). In embodiments, Voh / Voh>1.05, more especially Voh / Voh>l.l (for at least one kl luminescent materials).

[0047] Accordingly, also in specific embodiments a majority of the pristine luminescent material is absent in the subregions. For instance, in embodiments no more than 10 vol% of one or more of the non-recycled luminescent materials is comprised by the subregions. In further embodiments no more than 1 vol% of one or more of the non-recycled luminescent materials is comprised by the subregions. In further specific embodiments, the subregions do not comprise one or more (especially all) of the non-recycled luminescent material.

[0048] As described above, it was further noticed that especially (recycled) first luminescent materials may be configured in clusters in the luminescent material element. Clustering may especially be noticed if the recycled luminescent material is configured in a (first) layer. In embodiments (particulate material comprising) recycled luminescent material of a garnet-type of phosphors may define one or more clusters of recycled luminescent material in the luminescent material element. Yet, in further embodiments (particulate material comprising) recycled luminescent material of a garnet-type of phosphors and a nitride-type of phosphors may define one or more clusters of recycled luminescent material in the luminescent material element. The cluster may in embodiments comprise (a cluster comprising particles of) a garnet type first luminescent material and a nitride type of second luminescent material. Yet in other embodiments, the cluster may comprise particles of two different types of first luminescent materials and optionally a second luminescent material. The subregion may in embodiments (thus) comprise one or more clusters. In embodiments, the luminescent material element comprises subregions comprising clusters of particles of kl luminescent materials selected from the nl first luminescent materials. In further embodiments, the luminescent material element (also) comprises subregions comprising clusters of particles of (i) one or more first luminescent materials and / or (ii) one or more second luminescent materials.

[0049] Furthermore, in embodiments substantially all of the subregions may comprise (clusters of) any one of the (different) recycled first luminescent material and (if present) any one of the recycled second luminescent material. Alternatively, (one or more of) the subregions may comprise (clusters of) different luminescent materials. Further, one or more of the subregions may not comprise any cluster of (different or the same) luminescent materials. In specific embodiments, the clusters comprise luminescent materials selected from the nl first luminescent materials and optionally the n2 second luminescent materials.

[0050] In further specific embodiments at least 5%, such as at least 10% of a total number of subregions, especially at least 20% of a total number of subregions, may comprise clusters of a single type of first luminescent materials (and / or in embodiments of a single type of second luminescent materials). Yet, in other specific embodiments at least 5%, such as at least 10% of a total number of subregions, especially at least 20% of a total number of subregions, may comprise clusters of particles of kl luminescent materials selected from the nl first luminescent materials and from the n2 second luminescent materials).

[0051] In further embodiments at least 5%, such as at least 10%, of a total number of subregions, especially at least 20% of a total number of subregions, may comprise clusters of particles of (i) one or more first luminescent materials and / or (ii) one or more second luminescent materials.

[0052] As described above, the luminescent material element may in embodiments comprise a plurality of different types of clusters. The types of clusters may for instance differ in a number of different luminescent materials present in the cluster. The types of clusters may in further embodiments differ in a number of different first luminescent materials present in the cluster. Additionally, or alternatively, the types of cluster may differ in a number of second luminescent materials present in the cluster. The types of clusters may in further embodiments differ in the type(s) of first luminescent materials present in the cluster. Additionally, or alternatively, the types of clusters may in further embodiments differ in the type(s) of second luminescent materials present in the cluster.

[0053] The term “cluster” may especially refer to a plurality of different types of clusters. In embodiments, the luminescent material element, especially the subregions (in the luminescent material element) may comprise at least three different types of clusters, such as at least four different types of clusters, especially at least five different types of clusters, and in specific embodiments no more than ten different types of clusters. In specific embodiments, there may be z different types of clusters (in the luminescent material element, especially in the subregions), wherein z>3, wherein the different types of clusters differ in one or more of (a) a (total) number of different first luminescent materials and / or a (total) number of different second luminescent materials, and (b) types of different first luminescent materials and / or types of different second luminescent materials. The recycled luminescent materials may in embodiments at least partly be embedded in a host material, especially recycled host material (or ’’remaining matrix material”, see also above). Different host materials are known in the art. The host material may in embodiments e.g., comprise a silicone or an acrylate (polymer). Often used types of the host materials are, e.g., dimethyl siloxanes, diphenyl siloxanes, and a methyl-phenyl siloxanes with various fractions of methyl and phenyl groups. The host material may originate from the initial application of the luminescent material (element).

[0054] In specific embodiments, the (partly) embedded recycled luminescent material(s) may be embedded in a main host material (of the luminescent material element). The main host material (also indicated as “first main host material”) and the host material of the recycled luminescent material (s) (also indicated as “second main host material”) may in embodiments be comparable materials (e.g., silicones). Yet, based on aging or e.g., used raw materials and the production processes, the first main host material and the second main host material may have (sometimes slightly) different characteristics. The first main host material and the second main host material may in embodiments differ in a composition of the polymer in the host material. The first and / or second main host material may e.g., comprise one or more host materials of the group of siloxanes consisting of a dimethyl siloxane, a diphenyl siloxane, and a methyl-phenyl siloxane. Furthermore, a fraction of the methyl and phenyl groups in the methyl-phenyl siloxane may differ between a first methyl-phenyl siloxane and a further methyl-phenyl siloxane.

[0055] The first main host material and the second main host material may especially differ in one or more of chemical composition and physical properties. An unlimited list of possible characteristics of the first main host material and the second main host material that may be different comprises, e.g., a relative amount of methyl and / or phenyl groups in the materials, a total fraction of crosslinks in the materials, a (average) molecular weight of the materials, a presence or concentration of impurities (types and / or amounts / percentages) in the materials, and a refraction index of the materials. Yet also other characteristics known to the person skilled in the art may differ between the first and second main host materials.

[0056] Hence, in embodiments, the light generating device comprises a first main host material; wherein each subregion comprises a second main host material wherein the kl luminescent materials selected from the first luminescent materials and the second luminescent materials are (at least partly) embedded; wherein the subregions are embedded in the first main host material; and wherein the first main host material and the second main host material differ in one or more of chemical composition and physical properties. The first main host material and / or the second main host material may comprise one or more of a silicone and an acrylate (polymer). In embodiments, the first main host material and the second main host material may be different materials. In further specific embodiments the first main host material and the second main host material comprise one or more of a silicone and an acrylate (polymer); and especially chemical compositions of the first main host material and the second main host material differ.

[0057] In embodiments, a volume fraction of one or more non-recycled luminescent materials in the luminescent material element that is embedded in the second main host material is relatively low. For instance, in specific embodiments, no more than 5 vol%, especially no more than 1 vol%, such as substantially none, of one or more non-recycled luminescent materials is embedded in the second main host material.

[0058] Moreover, in specific embodiments at least one of the luminescent materials is embedded in the first host material and not in the second main host material (in the second volumes).

[0059] Especially, a larger part (> 50%) of the volume of the applied luminescent materials in the luminescent material element may originate from the recycled luminescent material, and only a lower volume percentage may be freshly added. In embodiments, e.g., a maximum of 40 vol.% of the luminescent material(s) in the luminescent material element is non-recycled luminescent material. In further embodiments no more than 30 %, such as no more than 25 vol.%, especially no more than 15 vol%, or even no more than 10 vol% of the luminescent material(s) in the luminescent material element is non-recycled luminescent material. The (relative) amount of non-recycled luminescent material is especially non-zero, and may e.g., be at least 0.1 vol%, especially at least 0.25 vol%, even more especially at least 0.5 vol%. The amount (or volume) of non-recycled luminescent material in the luminescent material element relative to a total of the luminescent materials in the luminescent material element may especially be selected from the range of 0.25 - 40 vol%, such as from the range of 0.5 -30 vol%, especially from the range of 0.5-25 vol%. In embodiments, relative to a total volume Vtjum of the luminescent materials in the luminescent material element, a total volume Vt inm hi of the luminescent materials embedded in the first host material (only) (and especially not in the second main host material) is selected from the range of 0.5-25%.

[0060] In specific embodiments, the recycled luminescent material (particles) (in combination with a first main host material) may be provided as a first deposit over the solid state light source light and the pristine luminescent material may be deposited (as a mixture and / or sequentially with the first host material) on top of the first deposit. Based on for instance the manufacturing process and material properties this may result in embodiments in two (distinct) layers. Further, in embodiments, (also when starting with a mixture of recycled and pristine phosphors) one or more of the recycled luminescent materials may settle out (sediment) in a larger extend than the non-recycled luminescent material (in the host material). This behavior may in embodiments be observed for recycled luminescent material comprising first luminescent materials (such as comprising cerium comprising garnet luminescent materials). In embodiments, embodiments of the first luminescent material may settle out in a larger extend than embodiments of the second luminescent material (also in embodiments of non-recycled luminescent material). Further, the particulate recycled material may in embodiments comprise a higher volume of first luminescent material(s) than of second luminescent material(s). This also may result in a presence of different layers in the luminescent material element. It will be understood that combinations of above described techniques and phenomena may result in embodiments of the luminescent material element comprising at least two layers. In embodiments, the first layer may comprise at least part of sedimented luminescent materials.

[0061] In embodiments the light generating device may (thus) comprise a first layer comprising luminescent material, and a second layer comprising luminescent material. The first layer may especially be configured between the solid state light source and the second layer. Further especially one of the layers, especially the first layer, may have a higher weight percentage or volume percentage of (one or more of) the recycled luminescent materials and the other layer, especially the second layer, may have a higher weight percentage or volume percentage of the non-recycled luminescent material. The second layer may in embodiments comprise substantially all of the non-recycled luminescent materials. The second layer may in embodiments comprise no more than six different luminescent materials, such as five different luminescent materials at maximum. In embodiments, the second layer comprises four different luminescent materials at maximum, even more especially three different luminescent materials at maximum, such as two luminescent materials at maximum and especially at least one luminescent material (of the nl first luminescent materials and the n2 second luminescent materials).

[0062] The first layer may in embodiments comprise more (different) luminescent materials than the second layer. For instance, in embodiments, the first layer may comprise at least three, especially at least four (different) luminescent materials. The first layer may in further embodiments comprise at least five (different) luminescent materials, such as at least six (different) luminescent materials, and in embodiments especially at least ten (different) luminescent materials. The first layer may especially comprise regions (of clusters) comprising first luminescent materials.

[0063] As indicated above, especially, the first layer may comprise a higher volume percentage of clusters than the second layer. In specific embodiments, a second volume percentage of clusters in the second layer is at least twice as low as a first volume percentage of clusters in the first layer. The second layer may in embodiments comprise substantially no clusters. The second volume percentage (of clusters) may in embodiments be zero. Furthermore, in embodiments especially garnet-types of luminescent materials may form clusters in the luminescent material element. These garnet types of luminescent materials may, e.g., originate from recycled (cool) white LEDs. Hence, in further embodiments, at least 10% of a total number of subregions, especially at least 20% of a total number of subregions, may comprise clusters of a (especially one or more) luminescent material of the types AsBsOn Ce, wherein A comprises one or more of Y, La, Gd, Tb and Lu, and wherein B comprises one or more of Al, Ga, In and Sc. In further embodiments at least part of one of the nl first luminescent materials and at least part of the n2 second luminescent materials may (also) define clusters in the subregions.

[0064] It is noted that in embodiments a further layer may be configured between the first layer and the second layer may in embodiments. The further layer may further be yet any other arbitrary layer, optionally without any luminescent materials. At least part of the first layer is especially configured further upstream from the solid state light source (with respect to the light source light) than the second layer.

[0065] It is further noted that a thickness of one or more of the layers, especially of the first layer, may vary over its volume. The (first) layer may for instance be deposited enclosing the solid state light source. The (first) layer may have a smaller thickness at locations configured over a top surface of the solid state light source than at locations configured at a side surface of the solid state light source. A thickness of the first layer may in embodiments be selected from the range of at least 50 pm, such as at least 100 pm, and in embodiments up to 500 pm, such as 300 pm at maximum, especially 200 pm at maximum, such as selected from the range of 50 pm - 500 pm, especially selected from the range of 50 pm - 300 pm(especially at locations configured at the top surface of the solid state light source). At locations configured at a side surface of the solid state light source the thickness of the first layer may be about 100 pm more. In further embodiments, a thickness of the second layer (at a location configured over the top surface of the solid state light source) may be selected from the range of at least 50 pm, especially at least 100 pm, and in embodiments 450 pm at maximum, such as 300 pm at maximum, especially 200 pm at maximum, such as selected from the range of 50 pm to 300 pm in embodiments. A total thickness of the luminescent material element may in embodiments be selected from the range of 200 pm - 500 pm, such as 200 pm - 400 pm, especially 200 pm - 300 pm (especially at locations configured at the top surface of the solid state light source).

[0066] Hence, in embodiments, the light generating device comprises a first layer and a second layer, wherein the first layer is configured between the solid state light source and the second layer. In embodiments, the first layer has a higher volume percentage of the nl first luminescent materials than the second layer. In further embodiments at least one of the n2 second luminescent materials is comprised by both the first layer and the second layer.

[0067] In embodiments, a (first) ratio of a volume fraction of at least one of the nl first luminescent materials in the second layer to a volume fraction of the respective one of the nl first luminescent materials in the first layer is especially smaller than a (second) ratio of a volume fraction of at least one of the n2 second luminescent materials in the second layer to a volume fraction of the respective one of the n2 second luminescent materials in the first layer. The term “volume fraction” in phrases like “a volume fraction of a respective luminescent material in layer” may especially relate to a fraction (v / v) of a total volume of the layer occupied with the respective luminescent material.

[0068] Moreover, in embodiments, a (first) ratio of a volume fraction of (a total of) the nl first luminescent materials in the second layer to a volume fraction of (a total of) the nl first luminescent materials in the first layer is especially smaller than a (second) ratio of a volume fraction (of a total) of the n2 second luminescent materials in the second layer to a volume fraction of (a total) of the n2 second luminescent materials in the first layer.

[0069] In further specific embodiments, the second layer comprises at maximum three different luminescent materials, especially wherein the first layer comprises at least five different luminescent materials. In further embodiments, the second layer comprises at least one first luminescent material that is not present in the first layer. Said at least one first luminescent material may in embodiments especially be a non-recycled luminescent material.

[0070] The terms “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”. As indicated above, the invention further provides in an aspect a method for providing a luminescent material element, especially the luminescent material element described above. In embodiments the method for providing the luminescent material element may comprise combining (the) nl first luminescent materials and (the) n2 second luminescent materials.

[0071] As indicated above, in specific embodiments, nl>3, n2>0, and especially (nl+n2)>5. In further embodiments at least three of the luminescent materials may be recycled luminescent materials. In embodiments, all of the luminescent materials are recycled luminescent materials. In specific embodiments, at least one of the luminescent materials is a nonrecycled luminescent material.

[0072] The recycled luminescent materials may in embodiments be derived from light emitting diodes especially having a correlated color temperature selected from a specific range, such as from a range of not broader than 2000 K, or a range of not broader than 1500 K, like e.g. selected from LEDs having a CCT in the range of 2000-4000 K (a range of 2000 K) or from LEDs having a CCT in the range of 2000-2700 K (a range of 700 K).

[0073] In specific embodiments, the luminescent materials are combined in such a way that irradiation of the luminescent material element, with (LED) light having a predefined peak wavelength (for instance comprising blue light), provides white light, wherein the white light comprises luminescent material light from the luminescent material element, and especially wherein the white light has a color rendering index of at least 65. In further embodiments, the white light may further optionally comprise (part of) the (blue) light having the predefined peak wavelength (being transmitted through the luminescent material element).

[0074] In specific embodiments, the method for providing a luminescent material element may comprise: combining (i) nl first luminescent materials (each) being configured to emit luminescent material light having a centroid wavelength in the 440-590 nm wavelength range and (ii) n2 second luminescent materials (each) being configured to emit luminescent material light having a centroid wavelength in the 590-780 nm wavelength range, wherein nl>3, n2>0, and (nl+n2)>5; wherein at least three of the luminescent materials are recycled luminescent materials, and wherein at least one of the luminescent materials is a non-recycled luminescent material, especially wherein the luminescent materials are combined in such a way that irradiation of the luminescent material element with (blue) light having a predefined peak wavelength provides white light comprising (i) luminescent material light from the luminescent material element and (ii) optionally the (blue) light having a predefined peak wavelength transmitted through the luminescent material element, and (the white light) having a color rendering index of at least 65.

[0075] In embodiments, the luminescent materials are embedded in a first main host material in the luminescent material element. As indicated above, the first main host material may in embodiments especially comprise a silicone (polymer). Additionally, or alternatively, the first main host material comprises an acrylate (polymer). The first material host material may be obtained by curing a precursor of the first material host material. During curing crosslinks may be formed in the precursor of the host material may to provide the (solid) host material.

[0076] Hence, in embodiments, the method for providing a luminescent material element comprises combining the luminescent materials and a precursor of a first main host material, to provide the luminescent material element wherein the luminescent materials are embedded in the first main host material, wherein the first main host material is selected from one or more of a silicone and an acrylate (polymer).

[0077] The invention further provides in an aspect a method for providing a light generating device (especially comprising recycled luminescent material). The provided light generating device especially comprises the light generating device described herein. The method for providing a light generating device, may in embodiments comprise providing (i) a solid state light source configured to generate light source light and (ii) the luminescent material element, and configuring the luminescent material element in a light receiving relationship with the solid state light source; especially wherein the luminescent material element is configured to convert at least part of the light source light into luminescent material light, and even more especially wherein the light generating device is configured to generate device light comprising the luminescent material light. The generated device light may in embodiments have a color rendering index of at least 65. The light source light may especially be blue light source light. The luminescent material element may especially be the luminescent material element described herein. Moreover, the luminescent material element may in embodiments be obtainable by the method for providing the luminescent material element.

[0078] The method may in embodiments comprise a calibration stage and a production stage. In the calibration stage, the spectral properties of the (mix of) recycled luminescent materials (especially in combination with the light source to be applied) may be determined. Based on the spectral properties of the recycled luminescent material and the desired spectral properties of the device light, (the type and amount of) the pristine luminescent material(s) to be added to the to the luminescent material element (in combination with the recycled luminescent material(s)) may be selected.

[0079] In embodiments, the calibration stage comprises: providing a solid state light source configured to generate (the) light source light; arranging the recycled luminescent material(s) to the solid state light source to provide an arrangement of the recycled luminescent materials and the solid state light source, wherein the recycled luminescent materials are configured in a light-receiving relationship with the solid state light source; measuring spectral properties of light emanating from the arrangement when the recycled luminescent materials are irradiated by the light source light; and defining the amount of the at least one non-recycled luminescent materials to be added to the arrangement to provide the light generating device (described herein).

[0080] In embodiments, the recycled luminescent material may be combined with a precursor of a first main host material and the recycled luminescent material(s) combined with the precursor is arranged to the solid state light source to provide the arrangement. In further embodiments, the precursor may be cured after arranging it to the solid state light source.

[0081] The production stage may especially comprise providing the (such) light generating device (based on the arrangement and the defined amount of the at least one nonrecycled luminescent materials to be added to the arrangement).

[0082] It will be understood that calibration may be done for every new mix of recycled luminescent materials, optionally in combination with the desired spectral properties of the device light provided by the light generating device. As such, the solid state light source used in the calibration stage may be selected comparable or identical to the solid state light source used in the production stage. The solids state light source used in the production stage and the solid state light source used in the calibration stage may especially not be the same solid state light source (but especially being identical to each other). Hence, in embodiments, the luminescent material element is provided (in the production stage) to a solid state light source not used in the calibration stage.

[0083] In embodiments, the production stage comprises providing a mixture of the recycled luminescent materials and the at least one non-recycled luminescent materials according to the amount of recycled luminescent materials used in the calibration stage and the amount of the at least one non-recycled luminescent materials to be added to the arrangement as defined in the calibration stage, and using the mixture in the production stage to provide the light generating device. The mixture may in embodiments comprise the recycled luminescent material comprising (particles comprising) recycled luminescent materials at least partly embedded in the second main host material and the at least one nonrecycled luminescent materials. The production stage further especially comprises combining said mixture with the precursor of the first main host material to provide the luminescent material element (to the solid state light source). The obtained light generating device may comprise the luminescent material element comprising in embodiments the first layer and the second layer. In embodiments the first layer may especially comprise (subregions comprising clusters comprising) (most of the) (sedimented) recycled luminescent materials and the second layer may especially comprise (most of) the at least one non-recycled luminescent materials.

[0084] In alternative embodiments, the production stage may comprise arranging the recycled luminescent materials to the solid state light source to provide the arrangement of the recycled luminescent materials and the solid state light source as described in relation to the calibration stage. Alternatively, the arrangement (already) used in the calibration stage may be used in the production stage. The production stage may further comprise providing the defined amount of non-recycled luminescent materials to be added to the arrangement, to the arrangement (in a mixture and / or sequentially with the precursor of the first main host material). With such production stage, the at least one non-recycled luminescent materials may in embodiments only be embedded in the first main host material (and not in the second main host material). In light generating devices obtained this way a total volume Vt,ium,hi of the luminescent materials embedded in the first host material only (i.e. not in the second main host material), relative to a total volume Vt,iumof the luminescent materials in the luminescent material element, may in embodiments be selected from the range of 40% at maximum, especially 30% at maximum, even more especially 25% at maximum, such as 20% at maximum, and in embodiments 10% at maximum, and especially at least 0.1%, such as at least 0.5%, for instance selected from the range of 0.5-25%.

[0085] Hence, in embodiments the production stage comprises providing the defined amount of non-recycled luminescent materials to be added to the arrangement used in the calibration stage, to this arrangement (used in the calibration stage).

[0086] The production stage may in embodiments comprise the method of providing a luminescent material element. The production stage may further especially comprise curing the precursor of the first main host material.

[0087] The light generating device may be part of or may be applied in e.g. office lighting systems, household application systems, shop lighting systems, home lighting systems, accent lighting systems, spot lighting systems, theater lighting systems, fiber-optics application systems, projection systems, self-lit 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, (outdoor) road lighting systems, urban lighting systems, green house lighting systems, horticulture lighting, digital projection, or LCD backlighting. The light generating device (or luminaire) may be part of or may be applied in e.g., optical communication systems or disinfection systems.

[0088] In a further aspect, the invention may further provide a lighting device comprising the light generating device. The lighting device may in embodiments comprise a plurality of (the same or different) light generating devices. In embodiments the lighting device comprises a lamp. In further embodiments, the lighting device comprises a luminaire. Hence, the invention further provides in embodiment, a lighting device selected from the group of a lamp and a luminaire, comprising the light generating device described herein. The luminaire may further comprise a housing, optical elements, louvres, etc. The lamp or luminaire may further comprise a housing enclosing the light generating system and / or the light generating device. The lamp or luminaire may comprise a light window in the housing or a housing opening, through which the system light may escape from the housing. The light generating device may further be part of a lighting unit and / or of a light generating system..

[0089] In embodiments, the light source is a light source that during operation emits (light source light) at least light at a wavelength selected from the range of 200-490 nm, especially a light source that during operation emits at least light at wavelength selected from the range of 380 - 490, such as selected from the range of 400-490 nm, even more especially in the range of 440-490 nm. This light may partially be used by the luminescent materials. Hence, in a specific embodiment, the light source is configured to generate blue light.

[0090] The terms “visible”, “visible light” or “visible emission” and similar terms refer to light having one or more wavelengths in the range of about 380-780 nm. The terms “light” and “radiation” are herein interchangeably used, unless clear from the context that the term “light” only refers to visible light. The terms “light” and “radiation” may thus refer to UV radiation, visible light, and IR radiation. In specific embodiments, especially for lighting applications, the terms “light” and “radiation” refer to (at least) visible light.

[0091] BRIEF DESCRIPTION OF THE DRAWINGS

[0092] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

[0093] Fig. 1 A schematically depicts embodiments of the light generating device and of the method to provide the light generating device;

[0094] Fig. IB schematically depicts some aspects of the luminescent material element;

[0095] Fig. 2 schematically depict some further aspects of the luminescent material element;

[0096] Fig. 3 depicts schematically depicts embodiments of lighting devices.

[0097] The schematic drawings are not necessarily to scale.

[0098] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0099] Fig. 1 schematically depicts an embodiment of the light generating device 100. The figure further depicts aspects of the method to provide the light generating device 100 and the method to provide the luminescent material element 200. In the figure, at the top and at the right (under “D”), embodiments of a “ready” light generating device 100 are depicted. The light generating device 100 especially comprises a solid state light source 10 and a luminescent material element 200. The solid state light source 10 is configured to generate light source light 11, for instance comprising blue light and / or violet light.

[0100] The depicted luminescent material element 200 comprises first luminescent materials 210, schematically indicated as non-filled spheres. The luminescent material element 200 further comprises the optional second luminescent materials 220 schematically indicated as solid black (filled) spheres. The luminescent material element 200 may especially comprise nl (different) first luminescent materials 210. The (nl) first luminescent materials 210 are especially (all) configured to emit luminescent material light 201 having a centroid wavelength in the 440-590 nm wavelength range (when being irradiated with light source light 11). The luminescent material element 200 may further comprise n2 (different) second luminescent materials 220. The (n2) second luminescent materials 220 are especially (all) configured to emit luminescent material light 201 having a centroid wavelength in the 590-780 nm wavelength range (when being irradiated with light source light 11). It is noted that in the figure, no distinction is made among different first luminescent materials 210 or among different second luminescent materials 220.

[0101] The (different) luminescent materials 210,220 especially have distinctive characteristics or properties as described above. The characteristic or properties of individual luminescent materials or of subregions 207comprising luminescent materials 210,220 and / or of clusters 295 of luminescent materials 210,220 (see e.g. Figs IB and 2) may for instance be determined using microscopy (e.g., optical or scanning electron microscopy (SEM)) on (cross) sections of the luminescent material element 200) optionally in combination with irradiating the luminescent material element 200 with excitation light to excite the luminescent materials 210,220. Additionally, or alternatively, SEM may be combined with energy dispersive X-ray spectroscopy to analyze variation in elemental composition of the (clusters) of luminescent materials 210, 220. Further, SEM-Cathodoluminescence may be used on clusters 295 in the luminescent material element 200 to differentiate between luminescent materials based on a variation in emission.

[0102] One or more of the first luminescent materials 210 and the second luminescent materials 220 may comprise recycled luminescent material 210,220. Further, in embodiments, one or more (especially the remaining luminescent materials) of the first luminescent materials 210 and the second luminescent materials 220 comprise non-recycled luminescent material 210*, 220*. It is noted that in embodiments at least one of the nl first luminescent materials 210 and the n2 second luminescent materials 220 may for a first part comprise a recycled luminescent material 210,220, whereas the remainder may comprise a non-recycled luminescent material 210*, 220*. A difference between a recycled luminescent material 210, 220 and a non-recycled luminescent material 210*, 220* may (sometimes) in the figure schematically be indicated with an asterisk. It is noted that for the ease of explaining the invention, the recycled luminescent materials 210,220 in the depicted embodiments comprise only first luminescent materials 210 and no recycled second luminescent materials 220. In other embodiments, this may be different. It is further noted that herein the reference numbers 210 and 220 may be used referring both to the recycled and the non-recycled luminescent materials, whereas if the asterisk is used, this may explicitly refer to nonrecycled luminescent materials 210*, 220*.

[0103] The luminescent material light 201 especially comprises a combination of luminescent material light 201 emitted by the first luminescent material(s) 210 and luminescent material light 201 emitted by the second luminescent material(s) 220.

[0104] Further, the luminescent material element 200 is configured such that at least part of the light source light 11 is converted by the luminescent material element 200 into luminescent material light 201 (during use). The luminescent material element 200 is especially configured in a light receiving relationship with the solid state light source 10. This especially indicates that at least part of the light source light 11 radiated by the solid state light source 10 will irradiate the luminescent material element 200 (and may - at least partly - be converted to luminescent material light 201). In the depicted embodiment, also a part of the light source light 11 is transmitted through the luminescent material element 200. The depicted embodiment of the light generating device 100 is therefore configured to generate device light 101 comprising luminescent material light 201 and light source light 11. The light generating device 100 may especially generate device light 101 having a color rendering index of at least 65. Moreover, the device light 101 especially comprises white light.

[0105] In embodiments, the luminescent material element 200 may comprise at least two, especially at least three, and even more especially at least four, first luminescent materials 210. At least part of the first luminescent materials 210 may originate from a mixture of recycled (luminescent material elements 200 of) (used) LEDs, especially white LEDs. In embodiments, (also) part of the second luminescent materials 220 (if present) comprises recycled luminescent material 220. The luminescent material element 200 may in embodiments comprise at least two, such as at least three, or even more, recycled first luminescent materials 210.

[0106] Further, in embodiments the luminescent material element 200 may comprise not any second luminescent material 220. Yet, typically, a total number (nl+n2) of first luminescent materials 210 and second luminescent materials 220 may be at least five. Furthermore, in embodiments, n2 may especially be at least 2.

[0107] The luminescent material element 200 may be provided with the method (for providing a luminescent material element) according to the invention. Said method comprises combining (nl) first luminescent materials 210 and (n2) second luminescent materials 220 (note that n2 may be zero.) The luminescent materials 210,220 are especially embedded in a host material, especially (at least in) the first main host material 281 in the method. The luminescent materials 210,220 are further in embodiments combined in such a way that irradiation of the luminescent material element 200, with light having a predefined peak wavelength, provides (white) light 101 comprising luminescent material light 201 from the luminescent material element 200, especially in combination with part of the light having the predefined peak wavelength (transmitted through the luminescent material element 200). The light having a predefined peak wavelength may especially comprise blue light.

[0108] In specific embodiments, at least three of the luminescent materials 210,220 are recycled luminescent materials, and further especially at least one of the luminescent materials 210,220 is a non-recycled luminescent material 210*, 220*. The recycled luminescent materials 210,220 may in embodiments be selected from luminescent materials (or luminescent material elements) from (used) light emitting diodes.

[0109] Fig. 1 A further depicts two embodiments of the methods of the invention; a first one, indicated with the Roman number I, at the top and a second embodiment, indicated with the Roman number II at the bottom. In general, the method for providing the light generating device 100 comprises: providing a solid state light source 10 configured to generate light source light 11 and the luminescent material element 200, and configuring the luminescent material element 200 in a light receiving relationship with the solid state light source 10 such that the luminescent material element 200 is configured to convert at least part of the light source light 11 into luminescent material light 201.

[0110] The method may comprise a calibration stage and a production stage. In the given figures only the recycled first luminescent materials 210 are depicted. Yet, in embodiments, at least part of these recycled first luminescent materials 210 may be replaced by recycled second luminescent materials 220.

[0111] Both embodiments depicted in the figure may comprise 4 stages, indicated at the top with stage “A” to stage “D”. Essentially, stage A and B for the two embodiments of the method are comparable. Stages A and B especially relate to the calibration stage. In stage A to B, a solid state light source 10 configured to generate light source light 11 is provided, and recycled luminescent materials 210,220 (220 is not depicted, yet as explained above may also not be excluded in embodiments) are added to the solid state light source 10 to provide an arrangement 190 of the recycled luminescent materials 210,220 and the solid state light source 10. The recycled luminescent materials 210,220 are especially configured in a lightreceiving relationship with the solid state light source 10. In stage B the luminescent materials 210,220 are embedded in (a precursor 1281 of) a first main host material 281. Stage B further comprises measuring spectral properties of light emanating from the arrangement 190 when the recycled luminescent materials are irradiated by the light source light 11. Stage B further comprises (although not depicted in the figure) defining the amount of the at least one non-recycled luminescent materials 210*, 220* to be added to the arrangement 190 to provide the light generating device 100.

[0112] Stage C and D especially relate to the production stage in which the light generating device 100 is provided. In the embodiment at the top, indicated with method I, in stage C, the defined amount of non-recycled luminescent materials 210*, 220* to be added to the arrangement 190 used in the calibration stage, is provided to this arrangement 190 used in the calibration stage in combination with the precursor 1281 of a first main host material 281. It is noted that the first host material 281 used in the calibration stage may in embodiments differ from the first host material 281 of the production stage. The term “first host material” (as well as” second main host material”) may relate to more than one different first host material 281 (or more than one different second main host materials 282).

[0113] Although explained this way in the figure, it will be understood that alternatively arrangements 190 may be made comparable to the arrangement 190 used in the calibration stage. One or more calibrations may be sufficient to provide a plurality of comparable arrangements 190 that may not need the measuring of the spectral properties of light emanating from the arrangement 190 when the recycled luminescent materials are irradiated by the light source light 11. Especially the defined amount of non-recycled luminescent materials 210*, 220* to be added to the arrangement 190 used in the calibration stage, is provided to this arrangement 190 used in the calibration stage or to a further arrangement 190 identical to the arrangement 190 used in the calibration stage.

[0114] In the depicted stage D, the precursor 1281 of the first main host material 281 is cured providing the first main host material 281 embedding the luminescent materials 210,220. The thus obtained light generating device 100 may comprise a first layer 291 and a second layer 292, the first layer 291 configured between the solid state light source 10 and the second layer 292. In embodiments, the first layer 291 has a higher (volume) fraction of one or more of the (nl) first luminescent materials 210 than the second layer 292. For instance, a volume fraction of one of the first luminescent materials in the first layer 291 may be 0.15 and a volume fraction of said first luminescent material in the second layer 292 may be less 0.05 or even 0. The higher volume fraction may be the result of the high amount of first luminescent material 210 in the recycled luminescent materials 210,220, relative to the amount of non-recycled first luminescent material(s) 210*. It is noted that also for the embodiment depicted in Fig. 2 this may be true. In further specific embodiments, a (volume) fraction of one of the (n2) second luminescent materials 220 may (also) be higher in the first layer 291 than a volume fraction of said second luminescent material in the second layer 292.

[0115] In the embodiment at the bottom, indicated with method II, stage C comprises combining (particles of) recycled luminescent materials 210,220 and non-recycled luminescent materials 210*, 220* with a precursor 1281 of a first main host material 281 into a mixture and sequentially arranging the mixture to the solid state light source 10. The recycled luminescent materials 210,220 and the non-recycled luminescent materials 210*, 220* and their respective amounts are especially selected to correspond to the recycled luminescent materials 210,220 and their respective amounts used in the calibration stage to provide the arrangement 190 of the recycled luminescent materials 210,220, and the defined amount of the non-recycled luminescent materials 210*, 220* to be added to the arrangement 190 to provide the light generating device 100 as determined in the calibration stage. Moreover, especially the solid state light source 10 used in the production stage corresponds to the solid state light source 10 used in the calibration stage.

[0116] Fig. IB schematically depicts a detail of the luminescent material element 200. At the left hand side, a representation of a detail of (used) luminescent material comprising luminescent materials 210,220 in its luminescent material element 200, is depicted. Such luminescent material element 200 may in embodiments be used to provide the recycled luminescent material 210,220. At the right hand side, a detail of an embodiment of the luminescent material element 200 of the invention is depicted. The shaded squares schematically depict particles of luminescent material, herein also indicated as “phosphor particles” at least partly embedded in a matrix or “host material”. In the luminescent material at the left, the phosphor particles 210, 220 are evenly distributed over the matrix.

[0117] When harvesting or extracting luminescent material 210,220 from used luminescent material, the luminescent material may break up in small particulate material or herein also indicated as “particles”, indicated in the left figure with the dotted squares comprising luminescent materials 210,220 embedded in a matrix material indicated with reference 282. Moreover, the dotted squares also may indicate a cluster 295 of (different) luminescent materials. It is noted that some dotted squares may have boundaries out of the depicted part of the luminescent material and no luminescent particles 210,220 are pictured in that part.

[0118] In the depicted figure, all particles (or clusters 295) comprising the recycled luminescent materials 210,220 are alike and comprise a first luminescent material 210 (shown in two distinct locations in the subregion 207) and a second luminescent material 220 (also shown at two locations). This is just one example, other particle counts per cluster 295 may be possible (and will occur) as well. When using the particles of the recycled luminescent materials 210,220 indicated with the dotted squares to provide the recycled luminescent material 210,220 for the luminescent material element 200 of the invention, these particles may be mixed with non-recycled luminescent material 210*, 220* and especially a precursor 1281 of a first main host material 281. Based on that, the distribution of all the luminescent materials 210,220 in the luminescent material element 200 may be less even than when using only fresh luminescent material 210*, 220*. It is noted that also in this figure, the recycled and the non-recycled luminescent materials are indicated with the references 210, 220 and 210*, 220*, respectively. In the luminescent material element 200 of the invention at the right side, still the particles obtained from harvesting the luminescent materials 210,220 are identifiable. These particles may define subregions 207 comprising a (second) volume V2, comprising one or more recycled luminescent materials 210,220. Moreover, the subregions 207 may comprise clusters 295 of luminescent materials 210, 220 The subregions or cluster 207 may originate from the (used) luminescent material (e.g. of an LED) depicted at the left side, and showing locations at which the luminescent material may be partitioned during harvesting (grinding) the (recycled) luminescent material. It is noted that, although not depicted in Fig. IB, harvesting may result in a broad range of different subregions 207. Grinding, for instance, of used LEDs may in embodiments provide heterogeneously distributed particulate recycled luminescent material that may define heterogeneously distributed subregions 207 in the luminescent material element 200. Further, further processing, e.g., using a solvent to dissolve at least part of the recycled matrix material 282, may provide particulate recycled luminescent material that may provide subregions 207 in the luminescent material element 200 comprising less second main host material 282 than depicted in the right hand figure of Fig. IB. The first volume VI may especially enclose a total of the subregions 207. The first volume VI may enclose a summation of the second volume V2 (over all subregions 207).

[0119] The fresh luminescent materials 210*, 220* may especially be arranged between the subregions 207 and / or on top (or below) the subregions 207. The subregions 207 may in embodiments have a second volume V2 that may in embodiments be at least 5000 pm3(each). The second volume V2 may e.g., be cubic and have a size of about 25*25*25 pm3. The subregions 207 may in embodiments be spherical. However, the subregions 207 may essentially have any arbitrary shape.

[0120] It is further noted that only a few different luminescent materials 210, 220 are depicted for clarity reasons. It will be understood that additional luminescent materials 210,220 may be comprised in the luminescent material element 200 as well as in the subregion comprising recycled luminescent materials 210,220. Moreover, the second volume V2 as well as the subregions 207 may show a diversity in for instance size, content and clusters comprised by the subregion 207.

[0121] Fig. IB (at the right side), thus especially explains an embodiment of the luminescent material element 200 having a first volume VI, wherein the luminescent material element 200 comprises subregions 207 within the first volume VI. In embodiments, each subregion 207 may comprise a selection of kl luminescent materials 210,220 selected from the nl first luminescent materials 210 and the n2 second luminescent materials 220. Especially l<kl<(nl+n2). The figure further depicts non-recycled first luminescent material 210* 220* at several locations embedded in the first host material 281 and not in the second main host material 282. Based on the extraction process of the recycled luminescent materials 210,220, each subregion 207 comprises second main host material 282 embedding at least part of one or more of the recycled luminescent materials 210,220. Fig. IB depicts that that luminescent material element 200 comprises a first main host material 281, wherein the subregions 207 are embedded in the first main host material 281. Fig. IB further depicts that the particles of the luminescent material 210,220 (also comprising the second main host material 282) may especially have a larger average volume than the particles of the nonrecycled luminescent material210*,220*.

[0122] In embodiments, the first main host material 281 and the second main host material 282 are identical. However, at least because of an aging effect and especially also because the recycled luminescent material may originate from a mixture of used luminescent material elements 200, the first main host material 281 and the second main host material 282 may differ in one or more of chemical composition and physical properties. For instance, in embodiments the first main host material 281 and the second main host material 282 comprise a silicone and / or an acrylate and yet the chemical compositions of the first main host material 281 and the second main host material 282 differ. Moreover, the term “second main host material” 282 may refer to a plurality of different second main host materials 282 (originating from different used luminescent materials and / or used luminescent material elements).

[0123] Fig. IB further also shows an embodiment wherein an average volume fraction of at least one of the kl luminescent materials in the first volume VI is smaller than a volume fraction of the at least one of the kl luminescent materials in a total of the second volumes V2.

[0124] The invention may especially aim in minimizing the use of fresh luminescent material 210*, 220*, relative to the use of recycled luminescent material 210,220. Therefore, relative to a total volume Vt,ium of the luminescent materials 210,220 (including non-recycled luminescent materials 210*, 220*) in the luminescent material element 200, a total volume Vt inm hi of the luminescent materials 210,220 embedded only in the first host material 281 (especially comprising the fresh luminescent materials 210*, 220*) may be less than 25% in embodiments. In the figure at the right this is very schematically indicated. In that figure only a detail is given of the luminescent material element 200. If this detail represents a representative image of the entire luminescent material element 200, then the total volume Vtjum may be represented by the volume defined by all luminescent particles 210,220 indicated with shaded squares within the outer perimeter P, and total volume Vt,ium,hi may be represented by all the luminescent particles 210*, 220* indicated with shaded squares that are not surrounded by the dotted squares, i.e. not being present in second volume V2 (within the perimeter P). It is noted that in the figure, all recycled luminescent materials 210,220 are mutually comparable to simplify the explanation. Yet, it will be understood that the recycled luminescent material 210,220, may define other kind of clusters 295. In further embodiments recycled particulate material 210,220 may comprise only a single type of phosphor 210,220 at least partly embedded in the second main host material 282, see e.g., Fig. 2. If such particle would be present, it would (also) be part of Vt,iumbut would not be part of Vt,ium,hi.

[0125] Fig. 2 also schematically depicts a luminescent material element 200 comprising a first layer 291 and a second layer 292, wherein the first layer 291 is configured between the solid state light source 10 and the second layer 292. A luminescent material element 200 comprising a first and a second layer may be obtained using the method I depicted in Fig. 1 A. Yet, the embodiment depicted in Fig. 2 may have been obtained using method II depicted in Fig. 1 A. Although in stage C the recycled luminescent materials 210,220 and the non-recycled luminescent materials 210*, 220* are mixed, the layers 291, 292 may be formed based on (faster) sedimentation of especially the recycled luminescent materials 210,220. Particles of recycled luminescent materials 210,220 (also comprising second main host material 282) may show a smoother surface than (some of the) pristine luminescent materials 210*, 220* and / or may be heavier because larger and may therefore settle out more easily (in the precursor 1281 of the first main host material 281) than the pristine luminescent materials 210*, 220*, which may result in the layered structure. The figure further depicts that various subregions 207 may have different second volumes V2 and shapes (only a few of the subregions 207 are indicated). The subregions 207 may comprise clusters 295 of luminescent materials 210,220. The figure further depicts that some subregions 207 may comprise both first and second luminescent materials 210,220, whereas other subregions 207 only comprise (optionally a plurality of) first luminescent materials 210. Yet further subregions 207 may comprise a cluster 295 of particles of only a single type of luminescent material 210,220 (and second main host material 282). In specific embodiments, the subregion may comprise a single luminescent material 210,220 particle at least partly embedded in the second host material 282. The luminescent material element 200, especially the (different) subregions 207 may in embodiments comprise different types of clusters 295, such as at least three types of clusters 295, especially at least four types of clusters 195, or even more types of clusters 295. The different types of clusters may for instance differ in one or more of (i) a number of different first luminescent materials 210, (ii) a number of second luminescent materials 220, (iii) types of different first luminescent materials 210, and (iv) types of different second luminescent materials 220.

[0126] It is noted that some subregions 207 may have been defined by the particles of the recycled luminescent material 210,220 as is explained in relation to Fig. IB. Some of these subregions are also indicated with reference 207” |The subregions 207” may comprise one or more clusters 295 of luminescent material 210,220. In some of the subregions 207, 207” smaller sub-subregions 207,207’ may be identified. Some of these sub-subregions 207 are also indicated with reference 207’. The subregions 207,207” may thus comprise one or more sub-subregions 207,207’. These smaller subregions 207’ may also comprises one or more (smaller) clusters 295 of luminescent material 210,220. Also the sub-subregions 207’ may have a second volume V2. As will be clear to the skilled person, when referring to a total or a summation of the second volumes V2 of the subregions 207, reference is made to a total of the second volumes V2 of the subregions 207, 207”, which (already, optionally) includes volumes of sub-subregions 207,207’. Hence, subregions 207’ are not added in the total / summation. The subregions 207, 207” as well as the sub-subregions 207, 207’ may (thus) comprise one or more clusters 295 of luminescent materials 210,220. It is noted that only a few clusters 295 are indicated in the figure. The clusters 295 are especially configured in the first layer 291. Further, especially first luminescent materials 210 appear to form clusters 295 more easily. It further appears that especially garnet-type first luminescent materials 210 may form clusters 295. Especially, in embodiments at least 100% of a total number of subregions 207 (or 207”) (in the luminescent material element 200) may comprise clusters 295 of a single type of first luminescent materials 210. Moreover, in specific embodiments at least 20% of a total number of subregions 207 comprise clusters 295 of a luminescent material of the type AsBsOn Ce, wherein A comprises one or more of Y, La, Gd, Tb and Lu, and wherein comprises one or more of Al, Ga, In and Sc.

[0127] The figure further schematically depicts an embodiment wherein the second volume percentage of clusters 295 in the second layer 292 is at least twice as low as a first volume percentage of clusters 295 in the first layer 291 (since no clusters 295 are present in the second layer 292). Moreover, the embodiment further depicts that the pristine luminescent materials 210*, 220* are embedded in the first main host material 281 (only), The pristine luminescent materials 210*, 220* and not form clusters 295. In the depicted embodiment the first layer 291 has a higher (weight or volume) percentage of the first luminescent materials 210 (210 and 210*) than the second layer 292. Furthermore, a first ratio may be defined by a volume percentage of the nl first luminescent materials 210 in the second layer 292 to the volume percentage of the nl first luminescent materials 210 in the first layer 292. A second ratio may be defined by a volume percentage of the n2 second luminescent materials 220 in the second layer 292 to the volume percentage of the n2 second luminescent materials 220 in the first layer 291. In the depicted embodiment, the first ratio is smaller than the second ratio.

[0128] Fig. 3 schematically depicts an embodiment of a luminaire 2 comprising the light generating system 1000 as described above. The light generation system 1000 comprises at least one light generating device 100. Moreover, in embodiments the term “light generating system” 1000 may be replaced by “light generating device” 100. The light generating system 1000 may be a light generating device 100. Reference 301 indicates a user interface which may be functionally coupled with a control system 300 comprised by or functionally coupled to the light generating system 1000. Fig. 3 also schematically depicts an embodiment of lamp 1 comprising the light generating system 1000 and / or the light generating device 100. Reference 3 indicates a projector device or projector system, which may be used to project images, such as at a wall, which may also comprise the light generating system 1000 and / or the light generating device 100. Fig. 3 schematically depicts embodiments of a lighting device 1200 selected from the group of a lamp 1, a luminaire 2, a projector device 3, a disinfection device, a photochemical reactor, and an optical wireless communication device, comprising the light generating device 100 as described herein. In embodiments, such lighting device 1200 may be a lamp 1, a luminaire 2, a projector device 3, a disinfection device, or an optical wireless communication device. The lighting device 1200 may especially comprise a lamp 1 and / or a luminaire 2, comprising the light generating device 100. Lighting device light escaping from the lighting device 1200 is indicated with reference 1201. Lighting device light 1201 may essentially consist of system light 1001 or device light 101, and may in specific embodiments thus be device light 101 or system light 1001. Reference 1300 refers to a space, such as a room. Reference 1305 refers to a floor and reference 1310 to a ceiling; reference 1307 refers to a wall.

[0129] The term “plurality” refers to two or more. The terms “substantially” or “essentially” herein, and similar terms, will be understood by the person skilled in the art. The terms “substantially” or “essentially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially or essentially may also be removed. Where applicable, the term “substantially” or the term “essentially” 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” also includes embodiments wherein the term “comprises” means “consists of’. The term “and / or” especially relates to one or more of the items mentioned before and after “and / or”. For instance, a phrase “item 1 and / or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term "comprising" may in an embodiment refer to "consisting of but may in another embodiment also refer to "containing at least the defined species and optionally one or more other species". Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0130] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. The devices, apparatus, or systems may herein amongst others be described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation, or devices, apparatus, or systems in operation. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0131] The invention further applies to a device, apparatus, or system comprising one or more of the characterizing features described in the description and / or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and / or shown in the attached drawings.

[0132] The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined.

[0133] Furthermore, some of the features can form the basis for one or more divisional applications.

Claims

CLAIMS:

1. A light generating device (100) comprising (i) a solid state light source (10) and (ii) a luminescent material element (200); wherein the solid state light source (10) is configured to generate light source light (11), wherein the luminescent material element (200) is configured to convert at least part of the light source light (11) into luminescent material light (201); wherein the light generating device (100) is configured to generate device light (101) comprising luminescent material light (201) and light source light (11) and having a color rendering index of at least 65; wherein the luminescent material element (200) comprises nl first luminescent materials (210) being configured to emit luminescent material light having a centroid wavelength in the 440-590 nm wavelength range, and n2 second luminescent materials (220) being configured to emit luminescent material light having a centroid wavelength in the 590-780 nm wavelength range, wherein nl>3, n2>0, and (nl+n2)>5, wherein the luminescent material element (200) has a first volume (VI), wherein the luminescent material element (200) comprises subregions (207) within the first volume (VI) with each subregion comprising a selection of kl luminescent materials selected from the nl first luminescent materials (210) and the n2 second luminescent materials (220), wherein l<kl<(nl+n2), wherein each subregion (207) has a second volume (V2), wherein the subregions (207) comprise clusters (295) of particles of one or more first luminescent materials (210) and / or one or more second luminescent materials (220), wherein there are z different types of clusters (295), wherein z>3, wherein the different types of clusters differ in one or more of (a) a number of different first luminescent materials (210) and / or a number of second luminescent materials (220), and (b) types of different first luminescent materials (210) and / or types of different second luminescent materials (220).

2. The light generating device (100) according to claim 1, wherein the second volumes (V2) are at least 5000 pm3, and wherein kl <3 ; and wherein an average volume fraction of at least one of the kl luminescent materials in the first volume (VI) is smaller than a volume fraction of the at least one of the kl luminescent materials in a total of the second volumes (V2).

3. The light generating device (100) according to any one of the preceding claims1-2, comprising a first main host material (281); wherein each subregion (207) comprises a second main host material (282) wherein the kl luminescent materials, selected from the first luminescent materials (210) and the second luminescent materials (220), are embedded; wherein the subregions (207) are embedded in the first main host material (281); and wherein the first main host material (281) and the second main host material (282) differ in one or more of chemical composition and physical properties.

4. The light generating device (100) according to any one of the preceding claims2-3, wherein at least one of the luminescent materials (210,220) is embedded in the first host material (281) and not in the second main host material (282).

5. The light generating device (100) according to claim 4, wherein relative to a total volume Vt,ium of the luminescent materials (210,220) in the luminescent material element (200), a total volume Vt,ium,hi of the luminescent materials (210,220) embedded in the first host material (281) only, is selected from the range of 0.5-25%.

6. The light generating device (100) according to any one of the preceding claims 1-5, wherein at least 10% of a total number of subregions (207) comprise clusters (295) of particles of a single type of first luminescent materials (210).

7. The light generating device (100) according to any one of the preceding claims, wherein nl>4 and wherein n2>2.

8. The light generating device (100) according to any one of the preceding claims, comprising a first layer (291) and a second layer (292), wherein the first layer (291) is configured between the solid state light source (10) and the second layer (292); wherein a first ratio of a volume fraction of the nl first luminescent materials (210) in the second layer (292) to a volume fraction of the nl first luminescent materials (210) in the first layer (292) is smaller than a second ratio of a volume fraction of the n2 second luminescent materials (220) in the second layer (292) to a volume fraction of the n2 second luminescent materials (220) in the first layer (291).

9. The light generating device (100) according to claim 8 and according to claim 6, wherein a second volume percentage of clusters (295) in the second layer (292) is at least twice as low as a first volume percentage of clusters (295) in the first layer (291); and wherein at least 10% of a total number of subregions (207) comprise clusters (295) of a luminescent material of the type AsBsOn Ce, wherein A comprises one or more of Y, La, Gd, Tb and Lu, and wherein B comprises one or more of Al, Ga, In and Sc.

10. The light generating device (100) according to any one of the preceding claims, wherein the light source light (11) comprises blue light.

11. A method for providing a luminescent material element (200), the method comprising: combining nl first luminescent materials (210) being configured to emit luminescent material light having a centroid wavelength in the 440-590 nm wavelength range and n2 second luminescent materials (220) being configured to emit luminescent material light having a centroid wavelength in the 590-780 nm wavelength range, wherein nl>3, n2>0, and (nl+n2)>5; wherein at least three of the luminescent materials (210,220) are recycled luminescent materials (210,220), and wherein at least one of the luminescent materials (210,220) is a non-recycled luminescent material and wherein the luminescent materials (210,220) are combined in such a way that irradiation of the luminescent material element (200), with light having a predefined peak wavelength, provides white light comprising luminescent material light (201) from the luminescent material element (200) and optionally the light having a predefined peak wavelength transmitted through the luminescent material element (200), and having a color rendering index of at least 65.

12. A method for providing a light generating device (100) comprising: providing (i) a solid state light source (10) configured to generate blue light source light (11) and (ii) the luminescent material element (200) obtainable by the method according to claim 11, and configuring the luminescent material element (200) in a light receiving relationship with the solid state light source (10); wherein the luminescent material element (200) is configured to convert at least part of the blue light source light (11) into luminescent material light (201); and wherein the light generating device (100) is configured to generate device light (101) comprising the luminescent material light (201) and having a color rendering index of at least 65.

13. A lighting device (1200) selected from the group of a lamp (1), and a luminaire (2) comprising the light generating device (100) according to any one of the preceding claims 1-10 or obtained with the method according to any one of the claims 11-12.

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