Luminescent glazing structure for greenhouses

Abstract

A luminous glazing structure for a greenhouse is described, which comprises a glass plate for the greenhouse and a glass plate provided with Eu 2+ and one or more amorphous inorganic light-emitting thin film layers doped with Eu, 2+ the one or more amorphous inorganic light-emitting layers doped with Eu comprise or consist essentially of the elements Al and / or Si and the elements O and / or N, wherein the Si concentration is selected from 0 to 45 atomic %, the Al concentration is selected from 0 to 50 atomic %, the O concentration is selected from 0 to 70 atomic %, the N concentration is selected from 0 to 60 atomic %, and 2+ is selected from the range of 0.01 to 30 atomic %.

Description

[Technical field]

[0001] The present invention relates to a glazing structure for a greenhouse, in particular, but not exclusively, to a doped one or more Eu 2+ and a method for making such a luminescent glazing structure. [Background technology]

[0002] Greenhouses provide a controlled climate environment for efficient growth of plants and crops. To control and optimize the sunlight entering the greenhouse, various types of coatings have been developed that can be used to coat the glazing structures or plastic transparent sheets that are part of the greenhouse. Various pigment coatings, such as photo-selective reflective coatings or diffusive coatings, with different optical properties are available to control the light entering the greenhouse. Typically, these coatings are spray coated and can be removed so that different coatings can be used depending on the season and / or the type of plants being grown. Examples of such coatings are described in WO 2018 / 169404, which describes removable coatings for greenhouses that include pigments, such as chalk or titanium oxide. Based on such pigment dispersions, during the summer, the glazing of the greenhouse can be spray coated with an infrared radiation reflective coating if the plants are sensitive to high levels of IR radiation. Similarly, diffusive coatings can be used to eliminate the shading effect and to uniformly expose the plants in the greenhouse to sunlight.

[0003] In the prior art, it has been suggested to further improve the coupling of sunlight to greenhouses on the basis of luminescent materials. Typically, these materials include transparent plastic sheets containing luminescent particles. Such materials can be optimized to convert a portion (or portions) of the radiation of the electromagnetic spectrum to different wavelengths for a more efficient use of said radiation. For example, an luminescent spectrum down-conversion layer applied as a luminescent coating on the glazing structure of a greenhouse can enhance the growth of crops by reducing the spectral mismatch between the solar spectrum and the photosynthetically active radiation (PAR) region of the crops (400nm-700nm) by converting UV light (100nm-400nm), which is often harmful to crops, into light in the PAR region that stimulates plant growth. For various vegetables growing in a greenhouse, a 1% increase in light in the PAR region can increase plant production by about 1%. Thus, such luminescent materials can have a great economic potential. Examples of such luminescent materials are described in U.S. Patent Application Publication No. 20170288080, which describes a luminescent coating for greenhouses that includes a polymer binder material with a fluorescent organic pigment, such as Lumogen 305, to absorb portions of the solar spectrum and use the energy of the absorbed photons to emit photons with wavelengths between 600 and 690 nm.

[0004] An interesting group of luminescent materials is based on inorganic rare earth compounds. These materials can be applied in the form of solution-based or particle-based coatings, which contain inorganic luminescent particles dispersed in a binder material (e.g. an organic binder material), or in the form of thin film layers formed using deposition techniques, e.g. sputtering. CN106893584 describes the use of Eu as an agricultural light conversion material for converting UV radiation in the 280-400 nm band into radiation in a narrow band of 610-620 nm. 3+The authors suggest the use of Al2O3 doped with ZnO (0.01-0.10%). The material has forbidden 4f-4f transitions resulting in a low LQE. Other examples of such luminescent materials are described in NL 1017077 and NL 2002577, which describe plastic foils for greenhouses that contain inorganic phosphors, in particular Y2O3-based phosphors, capable of converting part of the UV or IR into visible light.

[0005] Merkx et al. in their paper "Functionalizing window coatings with luminescence centers by combinatorial sputtering of scatter-free amorphous SiAlON:Eu 2+ In "Thin Film Composition Libraries", Journal of luminescence, 208 August 2018 pp. 51-56, authors describe SiAlON thin films. Certain Eu-doped polycrystalline SiAlON compositions, such as crystalline alpha and beta Eu-doped SiAlON, are known for application in white light-emitting diodes. The luminescent properties of these materials vary significantly depending on their composition, and the authors investigate the properties of amorphous thin films of specific Al:Si:Eu ranges in a SiAlON host with the aim of using the materials to generate electricity based on the principle of luminescent solar concentrators.

[0006] Despite the above mentioned prior art, the application of these luminescence conversion materials for large-scale greenhouse applications, such as luminescent glazing for greenhouses, is not yet commercially available. This is because known luminescent materials have overlapping absorption and emission spectra in the PAR region. Known luminescent phosphors for greenhouse applications, such as dyes, also suffer substantial loss of photons due to overlapping excitation and emission spectra, which makes these materials unsuitable for large-scale commercial applications. Furthermore, the luminescent coating should not only be able to efficiently convert parts of the UV spectrum into visible light, but also satisfy other properties such as low toxicity, chemical stability, environmental friendliness, cheapness, suitable for large-scale production, etc. More importantly, when the luminescent material is deposited as a thin film on the surface of a glazing with a certain thickness, the resulting luminescent glazing structure should not only be able to efficiently convert UV into light in the PAR part of the spectrum, but also have good anti-reflection properties, and should be able to effectively couple the light in the PAR part of the spectrum that comes out of the relatively thick glazing structure to the greenhouse.

[0007] In view of the foregoing, therefore, there is a need in the art for improved luminescent glazing structures for greenhouses, and in particular for improved luminescent glazing structures for greenhouses that exhibit broadband UV absorption and luminescent emission in the entire PAR range (wherein the absorption and emission spectra do not overlap), are transparent (non-absorbing) in the PAR range, exhibit high luminescent quantum efficiency (i.e., the ratio of emitted photons to absorbed photons), and efficiently couple PAR light exiting the glazing structure to the greenhouse. Summary of the Invention [Means for solving the problem]

[0008] It is an object of the present invention to reduce or eliminate at least one of the disadvantages known in the prior art.

[0009] In one aspect, the present invention provides a luminous glazing structure for a greenhouse, comprising a glass plate for a greenhouse and a glass plate having a Eu 2+ at least one amorphous inorganic light-emitting thin film layer doped with Eu 2+ At least one amorphous inorganic light-emitting layer doped with Eu comprises or consists essentially of the elements Al and / or Si and the elements O and / or N, the Si concentration being selected from 0 to 45 atomic %, the Al concentration being selected from 0 to 50 atomic %, the O concentration being selected from 0 to 70 atomic %, the N concentration being selected from 0 to 60 atomic %, and 2+ The present invention relates to the above luminescent glazing structure for a greenhouse, wherein the content of the luminescent glazing material is selected from the range of 0.01 to 30 atomic %.

[0010] In one embodiment, at least one of the one or more light-emitting thin film layers comprises Eu 2+ %, wherein the Si concentration is selected from 10 to 45 atomic %, the Al concentration is selected from 2 to 20 atomic %, the O concentration is selected from 30 to 70 atomic %, the N concentration is selected from 0 to 31 atomic %, and Eu 2+ can be selected from the range of 0.05 to 8 atomic %.

[0011] In one embodiment, at least one of the one or more light-emitting thin film layers comprises Eu 2+ %, wherein the Si concentration is selected from 20 to 45 atomic %, the Al concentration is selected from 2 to 10 atomic %, the O concentration is selected from 30 to 60 atomic %, the N concentration is selected from 0 to 31 atomic %, and Eu 2+ can be selected from 0.1 to 4 atomic %.

[0012] In a further embodiment, at least one of the one or more light-emitting layers comprises Eu 2+ A thin film layer of SiAlON doped with Eu 2+The composition of the SiAlON thin film layer doped with Eu may include Si: 38.4 atomic %, Al: 3.7 atomic %, O: 41.1 atomic %, N: 16.3 atomic %, Eu: 0.5 atomic %, and the percentages of the individual elements may vary by + / - 10%, preferably + / - 5%.

[0013] In one embodiment, the SiAlON:Eu 2 The thickness of the thin film can be selected from the range of 2000 to 10 nm, preferably 1000 to 30 nm, and more preferably 800 to 40 nm.

[0014] In one embodiment, the dimensions of the glazing include the length, width and thickness, wherein the length is selected from 300 to 100 cm, preferably from 250 to 140 cm, more preferably from 220 to 160 cm, the width is selected from 200 to 40 cm, preferably from 180 to 50 cm, more preferably from 160 to 60 cm, and the thickness is selected from 6 to 3 mm, preferably from 5.5 to 3.5 mm, more preferably from 5.0 to 3.5 mm.

[0015] In one embodiment, the luminescent glazing structure may further comprise a thin film anti-reflection (or AR) structure provided on the luminescent thin film layer to couple light into the glass sheet.

[0016] In one embodiment, the thin film AR structure can include at least one thin film of a porous oxide material, preferably a silicon dioxide material.

[0017] In one embodiment, the thin film anti-reflective AR structure may include a stack of dielectric thin film layers, the stack of dielectric thin film layers including one or more first layers of a first dielectric material having a first refractive index and one or more second layers of a second dielectric material having a second refractive index, where the second refractive index is higher than the first refractive index, and preferably at least a portion of the one or more first layers and the one or more second layers are stacked alternately on top of each other.

[0018] In one embodiment, at least a portion of the one or more luminescent thin film layers can be part of a thin film anti-reflective (AR) construction for coupling light, preferably light in the UV and PAR portions of the solar spectrum, into the glazing structure.

[0019] In one embodiment, at least a portion of the one or more first layers comprises Eu 2+ A low refractive index SiAlON layer doped with Al 3+ , N 3+ and Eu 2+ SiO2 layer doped with Eu 2+ a SiAlO layer doped with

[0020] In one embodiment, at least a portion of the one or more second layers comprises Eu 2+ A high refractive index SiAlON layer doped with Si, preferably 4+ , O 2+ and Eu 2+ AlN layer doped with Eu 2+ a SiAlN layer doped with

[0021] In one embodiment, at least a portion of the one or more second layers may include an undoped high refractive index SiAlON layer, preferably an undoped AlN layer or an undoped SiAlN layer.

[0022] In one embodiment, the glass platelet may include a first (top) surface and a second (bottom) surface, wherein the Eu 2+ One or more amorphous inorganic light-emitting thin film layers doped with Eu are provided on the first (top) surface, and the first (top) surface is further provided with a glass platelet and a Eu 2+ and preferably the surface texture has a standard deviation of a Gaussian scattering distribution of 20 degrees or greater at the light scattering interface.

[0023] In one embodiment, the one or more thin film layers include an upper surface for receiving solar radiation, the upper surface may include a surface texture for providing a light scattering interface, preferably the surface texture having a standard deviation of a Gaussian scattering distribution at the light scattering interface of 20 degrees or greater.

[0024] In one embodiment, the surface texture may comprise patterned cones, pyramids, microlenses with average dimensions in the nanometer range (10 nm to 1000 nm) or micrometer range (1 to 1000 micrometers), or the texture form is in the form of a (semi-)random texture with dimensions in the nanometer range or micrometer range, where the average dimensions are in the nanometer range (10 nm to 1000 nm) or micrometer range (1 to 1000 micrometers).

[0025] In one aspect, the present invention provides a method for the optimization of plant growth using Eu 2+ The present invention relates to an inorganic luminescent material doped with Al and / or Si and O and / or N, the luminescent material comprising or consisting essentially of the elements Al and / or Si and the elements O and / or N, the luminescent material being optimized for converting solar radiation in the UV region of the spectrum from 200 nm to 400 nm to radiation in the Photosynthetically Active Radiation (PAR) region from 400 nm to 700 nm. In one embodiment, the Si concentration in the inorganic luminescent material is selected from 0 to 45 atomic %, the Al concentration is selected from 0 to 50 atomic %, the O concentration is selected from 0 to 70 atomic %, the N concentration is selected from 0 to 60 atomic %, and Eu is selected from 0 to 10 atomic %. 2+ is selected from the range of 0.01 to 30 atomic %.

[0026] Ideally, a material for an agricultural spectrum down-conversion layer should meet certain requirements. The material should have advantageous luminescent properties, including broadband UV absorption, luminescent emission in the PAR region, transparency (non-absorption) for photons in the PAR region, non-overlapping absorption and emission spectra, and high luminescent quantum efficiency (LQE), i.e., the ratio of emitted photons to absorbed photons. In addition, the material should have optical, structural, and mechanical properties, including durability, hardness, and color stability, that are compatible with the material and / or application of the optical structure in which the luminescent material is used, such as a greenhouse glazing structure. In some applications, the material should not scatter, or at least have low scattering properties.

[0027] In another embodiment, the Si concentration in the inorganic luminescent material is selected from 10 to 45 atomic %, the Al concentration is selected from 2 to 20 atomic %, the O concentration is selected from 30 to 70 atomic %, and the N concentration is selected from 0 to 31 atomic %.

[0028] The luminescence conversion material is a material for optical structures, such as glazing structures, for greenhouses, such as Eu 2+ Amorphous SiAlON coatings doped with Eu 2+ It is particularly suitable for realizing SiAlON nanoparticles doped with .

[0029] For the sake of brevity, in this disclosure, Eu 2+ The SiAlON material (SiAlON:Eu 2+ ) references to the EU 2+ SiAlON doped with Eu 2+ SiAlO doped with Eu 2+ SiAlN doped with Eu 2+ SiON doped with Eu 2+ AlON doped with Eu 2+ Thus, the SiAlON material is a linear combination of the neutral units SiO2, Al2O3, AlN, and Si3N4, i.e. * SiO2+b * Al2O3+c* AlN+d * It may include any SiAlON stoichiometry that can be described as Si3N4 (where a, b, c, and d can take all values ​​independent of one another, including 0 and non-integer values).

[0030] EU 2+ doped SiAlON materials, especially Eu 2+ The optical properties of the amorphous SiAlON material doped with Eu have an ideal set of characteristics for a luminescence conversion layer (LCL) that can enhance plant growth in greenhouses. 2+ The material is completely transparent in the PAR region, has strong absorption in the UV region and emission in the PAR region, has no or at least little overlap in the absorption regions, and has a luminescent quantum efficiency (LQE) near 1. In addition, the material has excellent properties with respect to durability, including, for example, chemical stability, thermal stability, hardness, and color stability.

[0031] In one embodiment, the Eu 2+ The luminescent material consists essentially of the elements Al and / or Si and the elements O and / or N, where the term consists essentially of means that the material may contain trace amounts of other elements in amounts of 0.1% or less. 2+ The luminescent material is composed of the elements Al and / or Si and the elements O and / or N, or is composed of the elements Al, Si, O and N.

[0032] In one embodiment, the luminescent SiAlON:Eu 2+ The material can be an amorphous coating that exhibits low haze (less than 1 percent) in the PAR region. In this way, conversion losses due to scattered photons can be eliminated or at least substantially reduced. In one embodiment, such an amorphous coating can be produced using a sputtering method, such as reactive magnetron sputtering.

[0033] The luminescent SiAlON:Eu 2+ provides a wide tunable range of emission in the visible spectrum by varying the ratio of Si to Al and / or the ratio of O to N. In further embodiments, the emission can also be tuned by Eu 2+ As a result, the luminescent SiAlON:Eu 2+ A wide range of compositions of materials exist, corresponding to emissions in the blue to red range (400 nm to 700 nm), making these luminescent materials ideal for adapting the emission wavelength to the needs of the greenhouse farmer.

[0034] This range of Si-rich compositions produces luminescent SiAlON:Eu with high IQE, absorbing photons in the UV range of 200-400 nm and emitting photons in the PAR region. 2+ Brings substance.

[0035] In one embodiment, the luminescent SiAlON:Eu 2+ The material may have a composition of about 23 atomic % Si, about 9 atomic % Al, about 59 atomic % O, about 8 atomic % N, about 1 atomic % Eu, where the percentages of the individual elements may vary by + / - 10%, preferably + / - 5%. This composition provides a high LQE for a luminescent material that absorbs photons in the UV range 200-400 nm and emits in the PAR region.

[0036] The aforementioned luminescent SiAlON:Eu 2+ The materials may be used in optical structures, such as glazing structures for greenhouses, including glass sheeting coated with these materials.

[0037] In one embodiment, the glass platelet can be a highly transparent diffusive glass sheet having a high haze factor. In one embodiment, the diffusive glass platelet can have a light transmission of greater than 90% and a haze factor of greater than 70%. For example, the glass material can include one or more surfaces having optical scattering centers and / or textures to scatter light passing through the glass platelet. Thus, the Eu 2+ Luminescent radiation produced by the dopants and incident solar radiation passing through the optical structure is scattered in multiple directions, thereby producing diffuse light for photo-assisted crop growth.

[0038] Light scattering can be achieved by patterning or texturing one or both sides of the glass plate. Thus, in one embodiment, at least one surface of the glass plate can include a pattern and / or texture to scatter light in multiple directions.

[0039] In one embodiment, the SiAlON:Eu 2+ The luminescent layer may be configured as a diffusive coating to scatter the luminescent radiation and the incident solar radiation in multiple directions, in which case the luminescent layer may be a polycrystalline layer.

[0040] In one embodiment, the SiAlON:Eu 2+ The luminescent material may be integrated within and / or as part of the diffusive coating.

[0041] In one embodiment, the anti-reflective (AR) structure is made of SiAlON:Eu for optimal coupling of UV and solar light to the luminescent material. 2+ It may be provided on the luminescent material.

[0042] In one embodiment, the AR structure can include two or more dielectric layers, and the thickness and refractive index of the dielectric layers can be selected to form an AR structure for coupling UV and PAR to the luminescent layer. In one embodiment, the AR structure can be provided in a luminescent coating on a transparent substrate and can be optimized for coupling UV and PAR to the luminescent layer.

[0043] In one embodiment, the light-emitting layer may be provided on a glass platelet having a refractive index of about 1.5 In another embodiment, instead of the glass platelet, a transparent polymer-based platelet may be used.

[0044] In one embodiment, the AR structure can be a multi-layer AR structure comprising a stack of alternating low and high refractive index dielectric layers.In one embodiment, the low and high refractive index dielectric layers have a dielectric material that comprises elements Al and / or Si and elements O and / or N.In another embodiment, the low and high refractive index dielectric layers have a dielectric material that is (essentially) composed of elements Al and / or Si and elements O and / or N.

[0045] In one embodiment, the low refractive index dielectric layer may include a SiO2 layer. Such a layer may have a refractive index n of about 1.48 (may be referred to as a low n dielectric layer). In another embodiment, the high refractive index dielectric layer may include an AlN layer. Such a layer may have a refractive index n of about 2.16 (may be referred to as a high n dielectric layer). In a further embodiment, a silicon aluminum oxynitride SiAlON layer may be used for the dielectric layer with a refractive index n of 1.48-2.16 depending on the composition of the SiAlON. Based on these materials, an AR coating may be designed that can couple UV and visible light, especially PAR, to the light emitting layer.

[0046] In another embodiment, one or more luminescent SiAlON:Eu 2+The layer can be embedded in an anti-reflection structure. In one embodiment, the AR structure can be a multi-layer AR structure comprising a stack of alternating low and high refractive index dielectric layers, the low and high refractive index dielectric layers having a dielectric material containing the elements Al and / or Si and the elements O and / or N, and one or more of the low and / or high refractive index layers containing Eu. 2+ It's doped with.

[0047] In one embodiment, the low refractive index dielectric layer is Al 3+ and Eu 2+ The SiO2 layer doped with Eu, i.e., the luminescent SiAlO:Eu 2+ Such a layer has a refractive index of about 1.50. In another embodiment, the low refractive index layer is made of Eu 2+ The SiO2 layer doped with Eu, i.e. SiO2:Eu 2+ Such a layer has a refractive index of about 1.48. In one embodiment, the high refractive index dielectric layer is Si 4+ and Eu 2+ The AlN layer doped with Eu, i.e., the luminescent SiAlN:Eu 2+ Such a dielectric layer has a refractive index of about 2.14. In another embodiment, the medium refractive index layer is SiAlON:Eu, which has a refractive index of 1.48 to 2.16 based on the ratio of O to N. 2+ In this way, anti-reflective structures can be formed in which the reflectivity, transmission, and luminescence excitation and emission areas of the coating can be tailored.

[0048] In a further aspect, the present invention provides an optical structure comprising a transparent substrate having a first surface, a second surface and both surfaces, and at least one light-emitting layer provided on at least one of the first surface and / or the second surface of the transparent substrate, the light-emitting layer comprising or consisting essentially of the elements Al and / or Si and the elements O and / or N, 2+The doped inorganic luminescent material converts radiation in the UV region of the solar spectrum from 200 nm to 400 nm into the photosynthetically active radiation (PAR) region of the solar spectrum (400 nm to 700 nm), and the Si concentration in the inorganic luminescent material is selected from 0 to 45 atomic %, the Al concentration is selected from 0 to 50 atomic %, the O concentration is selected from 0 to 70 atomic %, the N concentration is selected from 0 to 60 atomic %, and Eu 2+ The present invention relates to the optical structure described above, wherein the content of the at least one element is selected from the range of 0.01 to 30 atomic %.

[0049] In one embodiment, the at least one light-emitting layer comprises Eu 2+ The SiAlON layer is doped with 0, in which the Si concentration is selected from 10 to 45 atomic %, the Al concentration is selected from 2 to 20 atomic %, the O concentration is selected from 30 to 70 atomic %, and the N concentration is selected from 0 to 31 atomic %.

[0050] In one embodiment, the at least one transparent substrate can be an inorganic transparent substrate, such as a glass substrate, or the transparent substrate is a polymer-based transparent substrate.

[0051] In one embodiment, the at least one transparent substrate has a high haze, preferably the transparent substrate is a diffuse type transparent substrate having a high haze, the high haze being higher than 70%, preferably higher than 80%, more preferably higher than 90%, and / or the light-emitting layer has a low haze, the low haze being lower than 20%, preferably lower than 10%, more preferably lower than 2%.

[0052] In one embodiment, the at least one light-emitting layer is an amorphous layer or a nanocrystalline layer.

[0053] In one embodiment, the transparent substrate can have a low haze level, the low haze level being less than 20%, preferably less than 10%, more preferably less than 2%, and / or the at least one light-emitting layer can have a high haze level, the high haze level being greater than 70%, preferably greater than 80%, or more preferably greater than 90%.

[0054] In one embodiment, the light emitting layer is polycrystalline or microcrystalline SiAlON:Eu 2+ The layer includes:

[0055] In one embodiment, Eu 2+ The concentration can be selected from at least one of the ranges of 0.1 to 25 atomic % and 0.2 to 20 atomic %.

[0056] In one embodiment, the optical structure may further comprise an anti-reflective AR coating, preferably a multi-layer AR coating, to couple light into the optical structure, preferably the AR coating is provided on the luminescent layer or the luminescent layer is part of or embedded in the AR coating.

[0057] In one embodiment, the AR coating may include a dielectric layer stack comprising one or more first layers of a first dielectric material having a first refractive index and one or more second layers of a second dielectric material having a second refractive index, the second refractive index being higher than the first refractive index, and preferably at least a portion of the one or more first layers and the one or more second layers are stacked alternately on top of each other.

[0058] In one embodiment, at least a portion of the one or more first layers comprises Eu 2+ A low refractive index SiAlON layer doped with Al 3+ , N 3+ and Eu 2+ SiO2 layer doped with Eu 2+and / or at least a portion of the one or more second layers include a SiAlO layer doped with Eu. 2+ A high refractive index SiAlON layer doped with Si, preferably 4+ , O 2+ and Eu 2+ AlN layer doped with Eu 2+ The SiAlN layer may include a SiAlN layer doped with .

[0059] In one embodiment, the optical structure may be optically connected to at least one photovoltaic cell, preferably to one of the two faces of the optical structure.

[0060] In one embodiment, at least a transparent near infrared photovoltaic cell may be provided on at least a portion of at least one luminescent layer, and preferably the optical structure further comprises an expandable reflective screen for reflecting light leaving the optical structure back into the optical structure through the second surface.

[0061] In a further aspect, the present invention may relate to a window assembly for a greenhouse comprising an optical structure according to any of the embodiments of the present application.

[0062] Therefore, the luminescent SiAlON:Eu 2+ The materials can form or be part of an anti-reflective structure or coating in a variety of ways, for example, the luminescent SiAlON:Eu containing relatively high amounts of Si (>32 at. %) and O2 (>64 at. %) (corresponding to a luminescent material with a high LQE). 2+ The composition of matter can have a refractive index lower than 1.51 (glass), making it suitable as an anti-reflective coating.

[0063] Alternatively, the luminescent SiAlON:Eu 2+ The material is alternating high and low refractive index SiAlON:Eu 2+ The composition may be incorporated into a multi-layer dielectric AR stack.

[0064] The invention will be further illustrated by reference to the attached figures, which show, in schematic form, embodiments according to the invention, it being understood that the invention is in no way limited to these specific embodiments. [Brief description of the drawings]

[0065] [Figure 1A] FIG. 1A shows a photograph of a luminescent thin film according to one embodiment of the present invention. [Figure 1B] FIG. 1B shows an XRD measurement of a luminescent thin film according to one embodiment of the present invention. [Figure 1C] FIG. 1C shows EDX measurements of a luminescent thin film according to one embodiment of the present invention. [Diagram 2] FIG. 2 shows the excitation and emission spectra of a luminescent thin film according to one embodiment of the present invention. [Diagram 3] FIG. 3 shows the transmission of a luminescent thin film according to one embodiment of the present invention. [Figure 4] FIG. 4 shows the haze of a luminescent thin film according to one embodiment of the present invention. [Diagram 5] FIG. 5 shows the attenuation spectrum of a luminescent thin film according to one embodiment of the present invention. [Figure 6] FIG. 6 shows a luminescent glazing for a greenhouse according to one embodiment of the present invention. [Figure 7A] FIG. 7A illustrates an embodiment of a luminescent glazing for a greenhouse including an anti-reflective structure according to various embodiments of the present invention. [Figure 7B] FIG. 7B illustrates an embodiment of a luminescent glazing for a greenhouse including an anti-reflective structure according to various embodiments of the present invention. [Figure 7C] FIG. 7C illustrates an embodiment of a luminescent glazing for a greenhouse including an anti-reflective structure according to various embodiments of the present invention. [Figure 8] FIG. 8 shows the modeled transmission of a thin film anti-reflective construction for greenhouse luminescent glazing according to one embodiment of the invention. [Figure 9A]FIG. 9A shows a luminescent glazing for a greenhouse including a surface scattering interface according to one embodiment of the present invention. [Figure 9B] FIG. 9B shows a luminescent glazing for a greenhouse including a surface scattering interface according to one embodiment of the present invention. [Figure 10A] FIG. 10A shows a luminescent glazing for greenhouses including a surface scattering interface according to another embodiment of the present invention. [Figure 10B] FIG. 10B shows a luminescent glazing for greenhouses including a surface scattering interface according to another embodiment of the present invention. [Figure 11A] FIG. 11A shows a luminescent particle-based anti-reflective coating according to one embodiment of the present invention. [Figure 11B] FIG. 11B shows a luminescent particle-based anti-reflective coating according to one embodiment of the present invention. [Figure 12A] FIG. 12A illustrates a luminescent glazing for a greenhouse according to various embodiments of the present invention. [Figure 12B] FIG. 12B illustrates a luminescent glazing for a greenhouse according to various embodiments of the present invention. [Figure 13A] FIG. 13A illustrates an electro-optic structure including luminescent materials according to various embodiments of the present invention. [Figure 13B] FIG. 13B illustrates an electro-optic structure including luminescent materials according to various embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0066] In the present disclosure, divalent europium (Eu) compounds having excellent and improved properties for greenhouse and crop growth applications are disclosed. 2+ ) doped SiAlON luminescent thin films are described. The improved properties include improved luminescent, optical and / or physical properties compared to conventional luminescent materials used in crop growth applications.

[0067] Surprisingly, certain SiAlON:Eu 2+ The composition contains Eu which absorbs UV and emits PAR. 2+It has been found that the absorption and emission spectra show little or no overlap. 2+ It has been found that SiAlON materials doped with Eu absorb a substantial part of the UV band of the solar spectrum and convert radiation in this band to radiation of longer wavelengths, in particular in the photosynthetically active radiation (PAR) range. SiAlON host materials exhibit excellent properties in terms of mechanical strength, chemical inertness and heat resistance, which is why they are used in the glass industry for protective and anti-reflective coatings. 2+ The SiAlON material doped with Eu forms a highly stable conversion material that is fully compatible with standard production processes in the glass industry. 2+ The SiAlON material doped with Eu does not scatter. 2+ The use of low scattering amorphous SiAlON thin film layers in solar conversion devices will ensure that the luminescent light does not escape the conversion device due to scattering.

[0068] The materials, their advantages, and their use in luminescent coatings for greenhouses and luminescent sheet structures for greenhouses are described in more detail below with reference to the accompanying drawings.

[0069] UV light induces amorphous SiAlON:Eu 2+ Photographs of a transparent substrate coated with a thin film (left) and an uncoated substrate (right) are shown. 2+ The coating was photographed under illumination with broadband UV light, which emits radiation in the PAR region, i.e., 400-700 nm. The thin film was deposited on a glass substrate using a sputtering process, as previously described, and was approximately 800 nm thick. 2+ A thin film layer was obtained.

[0070] The EU 2+The SiAlON thin films doped with 1×10 -9 The deposition was performed on glass substrates at room temperature using a base pressure of 1 bar. Prior to deposition, the substrates were cleaned in an ultrasonic cleaner with a soap solution for 15 minutes, then rinsed with acetone, ethanol, and deionized water. Deposition was performed using metallic Al (99.9995%), Si (99.999%), and Eu (99.99%) targets with a diameter of 5.08 cm, which were reactively co-sputtered for 11.25 hours using a DC power source of 30 W, an RF power source of 130 W, and an RF power source of 40 W, respectively. The deposition rate of Eu was reduced by a stainless steel mask with a pattern of concentric holes with a diameter of 5.45 mm, which shielded 50% of the surface of the Eu target. The process gas flow was conducted in the sputtering chamber at an operating pressure of 4×10 -2 The sputtering gas consisted of 18 sccm of 6N purity Ar, 0.75 sccm of 5N purity O2, and 13.25 sccm of 3N purity N2, all input in mbar. O2 and N2 were introduced close to the substrate, while Ar was introduced at the Si source. After the sputtering deposition, the thin film was annealed at 600°C for 30 minutes in a rapid thermal processing (RTP) system to activate the light emission. The annealing temperature was 5°C for 30 minutes. -1 annealing was achieved using a ramp rate of about 1000 nm and the RTP system was flushed with 9 SLM of N2 containing 7% H2 during the entire annealing procedure. Figure 1B shows an XRD measurement of the thin film of Figure 1A, indicating its amorphous nature. Figure 1C shows an EDX measurement of the same thin film, providing information on the composition of the material. The measurement indicates a composition of about 23 atomic % Si, about 9 atomic % Al, about 1 atomic % Eu, about 8 atomic % N, and about 59 atomic % O.

[0071] The excitation and emission spectra of the light-emitting layer of FIG. 1A are shown in FIG. 2. In particular, FIG. 2 shows the excitation and emission spectra of the amorphous SiAlON:Eu 2+ The excitation spectrum 202 and emission spectrum 204 of the thin film layer are shown. 2+Thin films were prepared using sputtering techniques as previously described. As shown in Figure 2, the spectra show little or no overlap and excellent UV absorption from 250-400 nm and PAR emission from 400 nm to 600 nm. The emission observed is consistent with that of Eu 2+ The wavelength where emission is strongest is the broadband attributed to the 5d → 4f transition of this particular SiAlON:Eu 2+ The composition is located at 467 nm.

[0072] Eu according to the embodiments described herein 2+ A variety of deposition techniques can be used to form thin films of SiAlON doped with Eu. The deposition process can be used to form amorphous SiAlON:Eu doped thin films on a substrate that can be used to form non-scattering or at least low-scattering amorphous greenhouse luminescent glazing structures. 2+ is designed to be formed.

[0073] In one embodiment, a sputtering method, preferably a reactive magnetron sputtering technique based on the elements Al, Si, O and N (SiAlON), can be used. The thin films can be deposited on various glazings of various materials, including but not limited to float glass, quartz glass, borosilicate glass, low iron glass, etc. The glazings can be maintained at room temperature or at elevated temperatures up to 650°C for glass and up to 1300°C for quartz. In a preferred embodiment, a low temperature deposition technique can be selected to deposit or grow the luminescent thin films.

[0074] EU 2+ An exemplary synthesis method for producing amorphous SiAlON thin films doped with may include the following steps: Prior to deposition, the substrate may be cleaned by rinsing with ethanol and / or deionized water; that deposition may be performed using separate Al, Si and Eu targets, and / or a combination of Al-Si-Eu targets (e.g., 71% Si, 28% Al, 1% Eu); During sputtering, the process gas flow may include a mixture of Ar, O2, N2, and H2 (e.g., 18 sccm Ar, 0.75 sccm O2, 13.25 sccm N2, and 0.4 sccm H2); After sputtering deposition, the sample may be annealed at a temperature between 50 and 1400°C to enhance the luminescence, preferably with an annealing step and annealing temperature selected that are compatible with the manufacturing processes of the glass industry; During annealing, the system may be flushed with forming gas containing H2 during the entire annealing procedure.

[0075] Amorphous SiAlON:Eu produced by the aforementioned sputtering process 2+ Glazing coated with the thin film layer exhibits excellent optical properties, such as transparency and haze in the PAR region. As shown in FIG. 2+ The transmission of the glazing shows >100% transmission in (part of) the PAR region and absorption in the UV region when irradiated with broadband UV light compared to uncoated glazing. In addition, the luminescent glazing has excellent optical properties, such as the haze shown in Figure 4. The haze (%) is compared to the haze of a plain quartz substrate (black line) and of an amorphous SiAlON:Eu formed on a quartz substrate. 2+ It represents the ratio of diffused transmission to total transmission of the film (grey line). Due to the amorphous nature of the coating, the haze in the visible range (400 nm to 700 nm) does not exceed 1%.

[0076] In one embodiment, the wet coating technique comprises depositing a SiAlON:Eu on the glazing structure. 2+It can be used to deposit thin films. In particular, sol-gel wet coating can be used. Solutions containing precursors of the elements Si, Al, O, N, and Eu can be prepared that can be applied directly onto the glazing by conventional wet coating techniques. Various post-deposition treatments, including annealing treatments, can be applied to the sol-gel coated glazing. Also, trace amounts of binder material precursors can be included in the liquid precursors for various purposes, such as controlling solution viscosity, increasing coating adhesion, minimizing coating porosity, modifying the coating surface morphology, etc.

[0077] SiAlON:E u2+ An exemplary sol-gel coating technique for forming a thin film coated glazing may include the following steps: Stoichiometric weighing of 7.7447 g Si(OC2H5)4, 0.3299 g Al(NO3)3, and 0.0681 g Eu2O3; Dissolve Eu2O3 in a minimum amount of dilute nitric acid; Dissolve Al(NO3)3 in ethanol and place it on a heating plate; Dissolve TEOS (Si(OC2H5)4) in ethanol and place it on a heating plate; mixing the TEOS solution with the Al(NO3)3 solution and the Eu2O3 solution to form a sol mixture; diluting the sol to a concentration of 10% by weight of oxide; Spray or spin coat the diluted solution onto the glass substrate and age it at 60° C. for 72 hours; Calcination at 500°C to completely remove organic residues; Annealing the coating at 1000°C in a reducing atmosphere using a flash annealing or rapid thermal processing facility.

[0078] Based on these deposition techniques, various SiAlON:Eu 2 Thin films can be produced, with 1 mole of SiAlON:Eu 2+ Eu per product2+ The dopant concentration may be selected from 0.01 to 49.99 mol % of cations (Si and Al), and the Si / Al ratio may be selected from 99:1 to 1:99. 2+ The dopant concentration may be selected from 0.5 mol % to 10 mol % of cations (Si and Al), and the Si / Al ratio may be selected from 20:1 to 1:20.

[0079] 5 shows the decay spectrum of a luminescent coating according to one embodiment of the present invention. In particular, the figure shows the SiAlON:Eu luminescent coating having a decay time of about 1 microsecond, which exhibits high luminescence quantum efficiency. 2+ 4 shows the extinction spectrum of the coating.

[0080] 6 illustrates a luminescent glazing structure for a greenhouse according to one embodiment of the present invention. As shown in the figure, the glazing structure may include a glazing 602 having a first surface 604 and a second surface 606, where the first surface may be configured to receive external sunlight 612 and the second surface may be configured to couple light 614 exiting the glazing structure to a greenhouse. The glazing structure may be part of or used in a greenhouse or house for growing crops indoors.

[0081] The length of the glazing may be selected from 300 to 100 cm, preferably from 250 to 140 cm, more preferably from 220 to 160 cm, and the width of the glazing may be selected from 200 to 40, preferably from 180 to 50 cm, more preferably from 160 to 60 cm. Typical dimensions (length x width) may include 2.140 x 1.122 mm, 1.650 x 1.22 mm, 1.650 x 997 mm, and 1.650 x 730 mm. Furthermore, the glazing may have a thickness of 6 to 3 mm, preferably from 5.5 to 3.5 mm, more preferably from 5.0 to 3.5 mm.

[0082] SiAlON:Eu 2The thin film 608 can be deposited on the first surface of the substrate based on a sputtering method or a sol-gel method. 2 The thickness of the thin film may be 2000 to 10 nm, preferably 1000 to 50 nm, and more preferably 800 to 80 nm. 2 The composition of can be selected such that efficient UV absorption is achieved without the need for relatively thick thin film layers. This requirement is important because the thickness and refractive index of the luminescent layer will contribute to the optical properties of the luminescent glazing structure.

[0083] A broadband anti-reflection (AR) thin film structure 610 may be provided on the luminescent thin film to reduce the percentage of reflected light and allow a higher transmission through the glass to be achieved. The AR thin film structure may include one or more thin film layers of low refractive index materials. In one embodiment, the AR thin film structure may include at least one porous SiO2 thin film layer. Porous SiO2 thin films are known to have good anti-reflection properties and are used as AR coatings for solar cells. An additional advantage of porous SiO2 is that the presence of scattering centers in the porous coating may increase the inherent volume scattering, thereby improving the outcoupling of light out of the glazing. The porous SiO2 coating may be based on reactive high power impulse magnetron sputtering at high working pressure as described in the article by Kim et al., Anti-reflection porous SiO2 thin film deposited using reactive high power impulse magnetron sputtering at high working pressure for use in a-Si:H solar cells, in Solar Energy Materials & Solar Cells, 130 (2014) pp 582-586.Alternatively, these layers can be deposited using plasma enhanced chemical vapor deposition (PECVD) as described by Barranco et al., Room temperature synthesis of porous SiO2 thin films by plasma enhanced chemical vapor deposition, Journal of Vacuum Science & Technology A 22, 1275-1284 (2004), or by co-sputtering the coating with a soluble material (e.g., a halide, such as NaCl) followed by water immersion to remove the soluble material and obtain a porous sponge-like structure as described by Dedoncker et al., Sputter deposition of porous thin films form metal / NaCl powder targets, App. Phys. Lett, 115, 041601 (2019). The contents of these articles are incorporated herein by reference.

[0084] In addition to and / or in the alternative to porous ARC films such as those shown in Figure 6, other types of AR film structures may also be used. For example, the AR film structure may include multiple thin film layers (thin film stacks), where in some embodiments, one or more of the multiple thin film layers is SiAlON:Eu 2 It may be a thin film layer.

[0085] 7A and 7B show embodiments of a greenhouse luminescent glazing that includes a multilayer anti-reflective structure according to various embodiments of the present invention. For example, FIG. 7A shows one embodiment of a greenhouse luminescent glazing in which the multilayer dielectric thin film stack is SiAlON:Eu 2+The at least one luminescent thin film layer may comprise, for example, a Eu-doped SiAlON thin film layer and a Eu-doped SiAlO thin film layer. The multi-layer dielectric thin film stack is configured as an anti-reflective (AR) coating for UV and PAR light. In particular, the figure shows a schematic diagram of an optical structure including a glazing 7021 having a first surface 7061 and a second surface 7041, where at least one luminescent layer 7081 is provided on the first surface and a dielectric multi-layer AR coating 710 for UV and PAR is provided on the second surface. 1~7 is provided in the light-emitting layer.

[0086] In one embodiment, the anti-reflection structure may include two or more dielectric layers, the thickness and refractive index of the dielectric layers being selected to form an AR structure for glazing of glass compositions typically having a refractive index of about 1.5. In one embodiment, such an AR thin film structure may be provided in greenhouse glazing, i.e., one or more luminescent layers provided on glass platelets suitable for use in greenhouses. The dielectric thin film layer stack may include alternating high and low refractive index layers. Preferably, the high and low refractive index layers are SiAlON compositions or Eu 2+ The composition is composed of a SiAlON doped with

[0087] In one embodiment, the low refractive index dielectric layer may include, for example, a SiO2 layer or a dielectric layer of a material with a refractive index similar to (or lower than) SiO2. Such a layer may have a refractive index of about 1.5 or less (referred to as low-n dielectric material). In another embodiment, the high refractive index dielectric layer may include, for example, an AlN layer or a dielectric layer of a material with a refractive index similar to (or higher than) AlN. Such a layer may have a refractive index of about 2 or more (referred to as high-n dielectric material). In a further embodiment, an oxynitride SiAlON layer may be used for the dielectric layer with a refractive index of 1.48 (SiO2) to 2.16 (AlN), depending on the composition of the SiAlON. Based on these materials, an AR coating may be designed that can couple UV and visible light, especially PAR, to the light emitting layer.

[0088] In one embodiment, the multi-layer AR coating may include a stack of dielectric layers, in this case seven dielectric layers of thickness and composition: 150.36 nm (low n layer 7101) / 13.01 nm (high n layer 7102) / 27.99 nm (low n layer 7103) / 43.90 nm (high n layer 7104) / 11.56 nm (low n layer 7105) / 32.64 nm (high n layer 7106) / 81.43 nm (low n layer 7107), where the low n dielectric material may be SiO2 and the high n dielectric material may be AlN. Note that the layers in Figures 7A and 7B are merely schematic and do not precisely represent the thicknesses of the layers. Modeled light transmission through such a multi-layer AR coating is provided in Figure 8.

[0089] 7B shows one embodiment of a luminescent glazing for a greenhouse, where a luminescent multilayer dielectric thin film stack is provided on a first surface of the glazing structure. In particular, the figure shows a glass glazing 7022 having a first surface 7062 and a second surface 7042, and a dielectric multilayer AR thin film structure 712 for UV and PAR that includes one or more luminescent layers. 1~5 1 shows a schematic diagram of a luminescent glazing for a greenhouse, comprising:

[0090] In this embodiment, the dielectric thin film stack may include one or more luminescent layers. Thus, in this embodiment, the luminescent material may be integrated or embedded in an AR structure that is configured to couple UV and PAR light to the coating. In one embodiment, the low refractive index (low n) dielectric layer is made of a small atomic percent of Al. 3+ , N 3+ and Eu 2+ Such a layer may include a SiO2 layer doped with ions. Such a layer has a refractive index of about 1.50. In one embodiment, the high refractive index (high n) dielectric layer contains a small atomic percent of Si 4+ , O 2+ and Eu 2+ It may include an ion-doped AlN layer. Such a dielectric layer has a refractive index of about 2.14. In one embodiment, the luminescent multilayer AR coating may include a dielectric layer stack, in this case five dielectric layers of thickness and composition 139.47 nm (low n layer 7121) / 12.30 nm (high n layer 7122) / 26.07 nm (low n layer 7123) / 100.86 nm (high n layer 7124) / 76.05 nm (low n layer 7125).

[0091] A sputtering process can be used to realize a stack of luminescent thin films AR. For example, a thin film stack having five layers can be realized based on the following process steps: Prior to deposition, the substrate may be cleaned by rinsing with ethanol and / or deionized water. Deposition may be carried out using separate Al, Si and Eu targets, and / or a combination Al-Si-Eu target (eg, 91.5% Si, 7.5% Al, 1% Eu). During sputtering, the process gas flow may include a mixture of Ar, O2, N2, and H2 (eg, 18 sccm Ar, 0.75 sccm O2, 13.25 sccm N2, and 0.4 sccm H2). The AR stack may include 5 layers, where: The top layer is a 91 nm thick SiAlO:Eu layer sputtered with 18 sccm Ar and 1.2 sccm O for 1201 s; The second layer was a 68 nm thick SiAlN layer sputtered with 18 sccm Ar and 14 sccm N2 for 3931 seconds; The third layer was a 26 nm thick SiAlO:Eu layer sputtered with 18 sccm Ar and 1.2 sccm O for 343 seconds; The fourth layer was a 26 nm thick SiAlN layer sputtered with 18 sccm Ar and 14 sccm N2 for 1503 seconds; The fifth layer was sputtered with 18 sccm Ar and 1.2 sccm O2 for 10558 seconds and may be as thick as necessary for sufficient luminescence conversion, for example 800 nm thick. During the sputtering deposition, the substrate may be heated to a temperature of 50-650° C. to enhance the light emission. After sputtering deposition, the sample may be annealed at a temperature between 50 and 1400° C. to enhance the luminescence, preferably with an annealing step and annealing temperature selected that are compatible with the manufacturing processes of the glass industry. During annealing, the system can be flushed with forming gas containing H2 during the entire annealing procedure.

[0092] Figure 7C shows a transmission graph of the light-emitting thin film AR structure. Table 1 provides a summary of the parameters of the three thin film layers that form the light-emitting thin film AR structure.

[0093] [Table 1]

[0094] The thin film is fabricated as a stack of thin films on a quartz substrate. FIG. 7C shows the measured transmission of the luminescent thin film AR structure in two different situations. These measurements are compared to the transmission of an uncoated quartz substrate, represented by line 720. The black dotted line 722 represents the simulated transmission of the luminescent thin film AR structure, where a 400 nm film blocks the UV portion of the solar spectrum. Thus, in that case, no conversion of UV light occurs and the thin film AR structure will function as a conventional AR coating. The effect of the AR coating on the transmission in the PAR region from 400 to 70 nm is clearly visible, showing an increase in transmission due to the anti-reflective properties of the thin film AR coating. The simulated transmission follows exactly the measured data (indicated by the grey "noisy" signal). The solid line 724 provides a guide to the experimental data without the film. These data clearly show the increase in transmission in the PAR region, especially in the 400-500 nm region, due to UV to PAR conversion. These graphs clearly demonstrate that a glazing structure having a luminescent thin film AR structure provides improved transmission of the glazing structure in the PAR region.

[0095] The luminescent glazing structure depicted in reference to Figures 7A-7C is a non-limiting list of many further embodiments that are possible without departing from the scope of the present invention. For example, the order of layers may be changed without departing from the scope of the present invention. Thus, in one embodiment, the one or more luminescent layers may be provided on top of the AR thin film stack (instead of being located below the AR thin film stack). In further embodiments, only one or more of the high or low refractive index layers may be made of Eu. 2+ It can be doped with

[0096] 9A and 9B show a luminescent glazing structure for a greenhouse according to another embodiment of the present invention. As shown in the figures, the glazing structure can include a glazing 902 having a first surface 904 and a second surface 906, where the first surface can be configured to receive external sunlight 912 and the second surface can be configured to couple light 914 exiting the glazing structure to a greenhouse. The glazing structure can be part of or used in a greenhouse or house for growing crops indoors. One or more SiAlON:Eu 2 A thin film structure 908 including thin film layers may be deposited on the first surface of the glazing based on a sputtering or sol-gel process. The thin film structure may include the luminescent thin film structure described with reference to Figures 6-8 above. The dimensions and thickness of the glazing may be similar to those of the greenhouse luminescent glazing structure described with reference to Figure 6.

[0097] In this embodiment, the thin film structure, e.g., SiAlON:Eu 2 The top surface of the thin film may be subjected to a surface treatment to introduce a light scattering top surface 910. The surface scattering interface may be introduced to maximize the coupling of light out of the second (bottom) surface of the glazing. The surface treatment may include an etching process that results in a textured surface.

[0098] The etching process can be a wet etching process or a dry etching process. A wet etching process works by dissolving surface portions by immersing the surface in a chemical solution. In one embodiment, a mask can be used to selectively etch the material. A dry etching process can be based on sputtering or dissolving the material. This can be achieved by a reactive ion etching process or an ion beam. The resulting surface features (and therefore scattering properties) can be tailored by adjusting various etching parameters (e.g., plasma feed gas, reactive gas type and flow, gas pressure, etching time, etc.) and measuring the scattering properties of the textured surface. The textured surface can have a regular (periodic) pattern or a random pattern.

[0099] The texture patterns may have features (diameter and height) in the nanometer to micrometer range. Texture features produced based on a mask-based etching process may include cones, pyramids, microlenses in the nanometer range (approximately 10 nm to 1000 nm), or features in the micrometer range, e.g., 1 micrometer to 500 micrometers. Alternatively, texture features produced based on a mask-les etching process may result in substantially random texture features with dimensions in the nanometer or micrometer range.

[0100] A measure of the surface roughness of the surface interface is the standard deviation of the Gaussian scattering distribution of light scattered at the surface interface. Such measurements are well known in the art, for example, Kurita et al., Optical surface roughness measurement from scattered light approximated by two-dimensional Gaussian function, Transactions on Engineering Sciences vol. 2, 1993. This paper is incorporated by reference into this disclosure.

[0101] The effect of surface scattering on the coupling of light out of the glazing structure of FIG. 9A is shown in FIG. 9B. In this example, the glazing structure is a 1 μm thick luminescent SiAlON:Eu 2 The figure includes a 50x50x1.1 mm Borofloat substrate with a thin film layer. The figure represents the escape efficiency of light escaping the glazing structure as a function of the surface roughness of the top interface, where curve 916 represents the escape efficiency of light escaping through the second (bottom) surface, curve 918 represents the escape efficiency of light escaping through the first (top) surface, and curve 920 represents the escape efficiency of light escaping through both sides.

[0102] This figure shows that increasing the scattering properties, i.e. the standard deviation of the Gaussian scattering distribution of the top interface, significantly improves the light dissipation from the bottom. As shown in this figure, the bottom escape efficiency 916 increases dramatically (more than 70% to 78%) with increasing scattering properties of the top surface. In one embodiment, the top surface is etched to introduce a surface texture with a standard deviation of the Gaussian scattering distribution of more than 20 degrees, which can result in an escape efficiency of about 70%. In this particular embodiment, the second surface 906 of the glazing and the interface between the first surface 904 of the glazing and the luminescent thin film are flat, non-scattering interfaces.

[0103] Luminescent films can be deposited on the surface of the glazing of diffuse glass by sputtering at low power and low temperature. In this way, lateral diffusion of dopants into the glazing can be substantially reduced, thereby achieving a low scattering interface. A highly scattering upper surface can include etching of the luminescent coating itself. The etching process can also reduce the refractive index of the upper interface and therefore provide an anti-reflection function.

[0104] 10A and 10B show a luminescent glazing structure for a greenhouse according to yet another embodiment of the present invention. The glazing structure may include a glazing 1002 having a first surface 1004 and a second surface 1006, the first surface may be configured to receive external sunlight 1012 and the second surface may be configured to couple light 1014 exiting the glazing structure to a greenhouse. The glazing structure may be part of or used in a greenhouse or house for growing crops indoors. One or more SiAlON:Eu 2 A thin film structure 1008 including thin film layers may be deposited on the first surface of the glazing based on a sputtering or sol-gel process. The thin film structure may include a luminescent thin film structure as described above with reference to Figures 6 to 8. The dimensions and thickness of the glazing may be similar to those of the greenhouse luminescent glazing structure described with reference to Figure 6.

[0105] In this embodiment, the one or more SiAlON:Eu 2 Prior to depositing a thin film layer on the surface of the glazing, the glass platelet may be subjected to a surface treatment to introduce a textured surface for light scattering, similar to that described by reference to Figures 9A and 9B. 2 After the thin film layers are deposited on the structured surface, a scattering interface 1010 is formed between the substrate and the one or more thin film layers. This scattering interface can also be used to maximize the coupling of light out of the second (bottom) surface of the glazing. 2 Depending on the thickness and deposition parameters of the thin film layers, the structure of the scattering interface can be reproduced in the top surface layer. This is shown diagrammatically in the figure by the textured top surface 1011. In another variant, the one or more SiAlON:Eu 2 The top surface of the thin film layer may be flat.

[0106] The effect of the scattering interface of both variants is shown in FIG. 10B. Here, a glazing structure similar to that described by reference to FIG. 9A is used. The figure shows how increasing the surface scattering of the scattering interface (i.e. between the glass substrate and the luminescent coating) is beneficial to increase the light scattering from the bottom. Here, the graphs 1018 (dissipation from the bottom) and 1020 (dissipation from the top) identified by dots relate to the case where the texture of the scattering interface is reproduced on the top interface (as shown in FIG. 10A), while the graphs 1016 (dissipation from the top) and 1016 (dissipation from the bottom) identified by triangles relate to the case where the texture of the scattering interface is not reproduced on the top interface. These graphs show that in the case where both the top surface and the interface have texture, the efficiency of scattering from the bottom increases as a function of the standard deviation of the Gaussian scattering distribution.

[0107] 11A and 11B show an exemplary luminescent glazing structure according to various embodiments of the present invention. As shown in these figures, the luminescent glazing structure includes a glazing, e.g., a first surface 1004. 1,2 and the second surface 1106 1,2 Glass plate 1102 having 1,2 where the first surface may be configured to receive external sunlight 1110, 1116 and the second surface may be configured to couple diffuse light 1114, 1118 exiting the optical structure to the greenhouse. As described in more detail below, in some embodiments, one or more first light-emitting layers 1108 1,2may be provided on the first surface of the substrate. Alternatively and / or in addition, in another embodiment, one or more second luminescent layers (not shown) may be provided on the second surface of the substrate. In one embodiment, the one or more first luminescent layers may be part of a layered structuring optimized for coupling light, particularly UV and PAR light, into the optical structure. For example, the luminescent layer may be part of a thin-film multi-layer anti-reflective structure optimized for coupling light, particularly UV and PAR light, into the optical structure. Similarly, the one or more second luminescent layers may be optimized for coupling light exiting the optical structure. A luminescent layer may be deposited (e.g., sol-gel or sputtering) directly on the surface of the glazing. Alternatively, one or more layers, such as an adhesion layer, a buffer layer and / or a passivation layer, may be deposited on the glazing before depositing a luminescent layer on the substrate.

[0108] 11A, the optical structure may include a substantially non-scattering or low scattering luminescent thin film layer 11081 and a highly scattering glazing 11021 (also referred to as a diffuse glass platelet). In one embodiment, the luminescent layer 11081 is an amorphous SiAlON:Eu 2000 Å layer having a haze of less than 3%, preferably less than 2%, and more preferably less than 1%. 2+ The SiAlON:Eu 2 The thickness of the thin film can be 2000-10 nm, preferably 1000-50 nm, more preferably 800-80 nm. Such layers can be realized using sputtering or sol-gel techniques as described herein. In a further embodiment, the light-emitting layer is a low scattering SiAlON:Eu 2+ Such layers can be nanoparticle coatings such as SiAlON:Eu in an inorganic or organic matrix material. 2+The matrix material may include nanoparticles. In one embodiment, the matrix material may be an amorphous dielectric material, such as SiAlON, Si3N4, Al2O3, Ti2O3, etc. In another embodiment, the matrix material may be a transparent organic dielectric material, such as PMMA, polyacrylic acid, polycarbonate, polyethylene, fiberglass, etc. Such nanoparticle coatings may be achieved based on suitable particle synthesis methods and coating techniques, as described herein.

[0109] The glazing 11021 may comprise a diffusive glass material, which may be optimized for light transmission (especially in the PAR region) and may simultaneously scatter light in random directions as it leaves the substrate. In one embodiment, the glazing may comprise a scattering structure to diffusely scatter the light. Instead of a glass substrate, a (diffusive) transparent polymer-based substrate may be used, which is provided with a light scattering structure, whereby diffuse light leaves the optical structure on the second surface.

[0110] The optical structure shown in FIG. 11A receives radiation in the solar spectrum ranging from UV radiation to IR radiation. The UV light is converted to PAR radiation by the divalent Eu dopants 1112 in the SiAlON layer. The doped SiAlON layer is transparent for radiation from the visible part, including the PAR region, which is to be introduced into the diffusing glazing. 2+ The PAR light 1014 produced by the doped sites and the PAR light 1118 from sunlight will exit the optical structure as diffused light, which is beneficial for plant growth.

[0111] 11B, the optical construction can include a highly scattering luminescent thin-film layer 11082 and a low scattering transparent substrate 11022. In one embodiment, the luminescent thin-film layer is a thin-film polycrystalline SiAlON:Eu 11022 disposed on a low scattering transparent substrate, such as a glass substrate or a transparent polymer-based substrate. 2+ In another embodiment, the thin film polycrystalline SiAlON:Eu 2+Instead, highly scattering microparticle-based coating layers can be used. Such layers are typically comprised of micron-sized SiAlON:Eu in an inorganic or organic matrix material. 2+ The matrix material may include particles. In one embodiment, the matrix material may be an amorphous dielectric material, such as SiAlON, Si3N4, Al2O3, Ti2O3, etc. In another embodiment, the matrix material may be a transparent organic dielectric material, such as PMMA, polyacrylic acid, polycarbonate, polyethylene, fiberglass. Such micron particle coatings may be achieved based on suitable particle synthesis methods and coating techniques, as described herein.

[0112] The optical structure shown in FIG. 11B receives radiation in the solar spectrum ranging from UV radiation to IR radiation, where UV light is converted to PAR radiation by the divalent Eu dopants 1112 in the SiAlON layer. 2+ The PAR light emitted by the material doped with Eu is scattered into the low scattering transparent substrate. Furthermore, the doped SiAlON layer acts as a scattering layer for the visible portion including the PAR region. Therefore, this portion of the sunlight is scattered into the diffusing substrate. 2+ The PAR light 1114 produced by the doped sites and the PAR light 1118 from sunlight will exit the optical structure as diffused light, which is beneficial for plant growth.

[0113] It is anticipated that the present invention is not limited to the optical structures described by reference to Figures 11A and 11B. For example, in further embodiments, the optical structure may include a highly scattering luminescent thin film layer and a highly scattering transparent substrate. Thus, the luminescent layer and the substrate are both configured to produce diffuse light leaving the optical structure. In such embodiments, the optical structure may be optimized to transmit and produce highly diffuse light in the PAR region when exposed to solar radiation.

[0114] Further, in an embodiment, instead of providing one or more emissive layers on a first surface (or in addition to providing one or more emissive layers on a first surface), a low scattering or low scattering emissive layer can be provided on a second surface of the transparent substrate, which can be either a highly scattering (diffuse) substrate or a low scattering substrate depending on the application.

[0115] 12A and 12B show electro-optical structures including luminescent materials according to various embodiments of the present invention. The embodiment shown in the figures includes an optical structure optically connected to a photovoltaic device for converting a portion of the light of the optical structure into electrical power. The optical structure can be one of the optical structures described by reference to some of the embodiments described herein. The electro-optical structure can be part of a luminescent glazing structure for a greenhouse. In general, such an optical structure includes a transparent substrate 1202 having a first surface and a second surface. 1,2 , and SiAlON:Eu 2+ One or more thin-film luminescent layers 1208 containing a base luminescent material. 1,2 The one or more thin-film light-emitting layers may be part of or may be covered by an anti-reflective coating, which is described in more detail with reference to FIGS.

[0116] FIG. 12A shows an example of an electro-optical structure, in which one or more photovoltaic cells 1210 can be optically connected to one of the two sides of a transparent substrate. The electro-optical structure can be part of a luminescent glazing structure for a greenhouse. In this particular embodiment, the optical structure formed by the transparent substrate and the one or more luminescent layers can form a light guide structure for guiding light, such as incident sunlight, or the light generated by the one or more luminescent layers is captured in the light guide and guided towards the end of the optical structure by internal reflection. This light can be absorbed by a photovoltaic cell and converted into electricity. Thus, the optical structure forms a luminescent solar concentrator (LSC) structure.

[0117] In one embodiment, the foldable reflective screen 1218 is in an unfolded state, thereby extending over at least a portion of the back surface of the optical structure. In this way, the reflective screen can prevent (part of) the solar radiation from entering the greenhouse, as shown in FIG. 12A, and can also help to increase the light capture in the optical structure. The reflective screen can be folded (unfolded) and (partially) unfolded (unfolded). In the unfolded state, the UV light of the sunlight that enters the optical structure through the light receiving surface of the optical structure is converted into PAR light. The resulting PAR light and most of the visible part of the sunlight are directed towards the second surface, where they leave the optical structure and enter the greenhouse. A portion of the light is captured by the optical structure and can be directed towards both sides of the optical structure, where it is converted into electricity by photovoltaic cells. In the unfolded state, the reflective screen reflects light back into the optical structure on the back side, thereby increasing the amount of light captured by the optical structure.

[0118] FIG. 12B shows another electro-optical structure, in which a (near) infrared photovoltaic conversion layer 1216 is at least partially formed from a glazing structure and a SiAlON:Eu 2+ One or more thin-film luminescent layers 1208 containing a base luminescent material. 1,2 The (near) infrared photovoltaic conversion layer 1216 is transparent to visible light (including PAR light) and can convert light from the (near) infrared part of the solar spectrum into electrical power. Examples of such NIR solar conversion devices are known in the art, see for example R. Lundt et al., “Transparent, near-infrared organic photovoltaic solar cells for window and energy-scavenging applications”, Applied Physics Letters, Volume 98, Issue 11, id. 113305 (3 pages) (2011).

[0119] The phraseology used herein is merely intended to describe certain embodiments and is not intended to limit the present invention. As used herein, the singular forms "a", "an" and "the" are intended to encompass the plural forms as well, unless the context clearly indicates otherwise. Furthermore, it will be understood that the words "comprise" and / or "comprising" as used herein specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0120] In addition to corresponding structures, materials, acts, and equivalents of all means or steps, functional elements in the following claims are intended to encompass any structure, material, or act for performing that function in combination with other claim elements as specifically claimed. The description of the present invention has been presented for illustrative purposes, but the description is not intended to be exhaustive or to limit the invention to the disclosed form. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the invention as set forth in the appended claims. The embodiments have been selected and described in order to best explain the principles and practical application of the invention, and to enable those skilled in the art to understand the invention in various embodiments with various modifications as suitable for the particular use contemplated.

Claims

1. A luminescent glazing structure for a greenhouse, comprising: A glass plate for a greenhouse, and a glass plate provided with Eu ２＋ wherein the Eu is doped into one or more amorphous inorganic light-emitting thin film layers. ２＋ the at least one amorphous inorganic light-emitting thin film layer doped with Eu 2+ is a SiAlON thin film layer doped with Eu 2+ ; The luminescent glazing structure for greenhouses, wherein the Si concentration is selected from 10 to 45 atomic %, the Al concentration is selected from 2 to 20 atomic %, the O concentration is selected from 30 to 70 atomic %, the N concentration is selected from 0 to 31 atomic %, and Eu 2+ is selected from 0.05 to 8 atomic %.

2. The Si concentration is selected from 20 to 45 atomic %, the Al concentration is selected from 2 to 10 atomic %, the O concentration is selected from 30 to 60 atomic %, the N concentration is selected from 0 to 31 atomic %, and Eu ２＋ is selected from 0.1 to 4 atomic %; 2. The greenhouse luminous glazing structure of claim 1.

3. At least one of the one or more amorphous inorganic light-emitting thin film layers doped with Eu 2+ ２＋ A thin film layer of SiAlON doped with Eu ２＋ 3. The greenhouse luminescent glazing structure according to claim 1 or 2, wherein the composition of the SiAlON thin film layer doped with is: Si: 38.4 at.%, Al: 3.7 at.%, O: 41.1 at.%, N: 16.3 at.%, Eu: 0.5 at.%, and the percentages of the individual elements may vary by + / - 10%.

4. A luminescent glazing structure for greenhouses as described in claim 3, wherein the percentages of the individual elements may vary by + / - 5%.

5. The greenhouse luminescent glazing structure according to any one of claims 1 to 4, wherein the thickness of the Eu 2+ -doped SiAlON thin film layer is selected from 2000 to 10 nm.

6. The greenhouse luminescent glazing structure according to claim 1, wherein the thickness of the Eu 2+ -doped SiAlON thin film layer is selected from the range of 1000 to 20 nm.

7. The greenhouse luminescent glazing structure according to claim 1, wherein the thickness of the Eu 2+ -doped SiAlON thin film layer is selected from the range of 800 to 30 nm.

8. The greenhouse luminescent glazing structure according to claim 1, wherein the thickness of the Eu 2+ -doped SiAlON thin film layer is selected from the range of 400 to 40 nm.

9. 9. The greenhouse luminous glazing structure according to any one of claims 1 to 8, wherein the dimensions of the glass plate include a length, a width and a thickness, wherein the length is selected from 300 to 100 cm, the width is selected from 200 to 40 cm, and the thickness is selected from 6 to 3 mm.

10. The greenhouse luminescent glazing structure according to any one of claims 1 to 9, further comprising a thin film anti-reflection structure provided on the one or more Eu2+ doped amorphous inorganic luminescent thin film layers for coupling light into the glass plate.

11. 11. The greenhouse luminescent glazing structure of claim 10, wherein the thin film anti-reflective structure comprises at least one thin film of a porous oxide material.

12. 12. A greenhouse luminescent glazing structure as described in claim 10 or 11, wherein the thin film anti-reflection structure comprises a stack of dielectric thin film layers, the stack of dielectric thin film layers comprising one or more first layers of a first dielectric material having a first refractive index and one or more second layers of a second dielectric material having a second refractive index, wherein the second refractive index is higher than the first refractive index.

13. A greenhouse luminescent glazing structure as described in claim 12, wherein at least a portion of the one or more first layers and the one or more second layers are stacked alternately on top of each other.

14. 10. The greenhouse luminescent glazing structure of claim 1, wherein at least a portion of the one or more amorphous inorganic luminescent thin film layers doped with Eu 2+ is part of a thin film anti-reflective structure for coupling light into the greenhouse luminescent glazing structure.

15. A greenhouse luminescent glazing structure as described in any one of claims 1 to 9, wherein at least a portion of one or more amorphous inorganic luminescent thin film layers doped with Eu 2+ is part of a thin film anti-reflective structure for coupling light in the UV and PAR portions of the solar spectrum into the greenhouse luminescent glazing structure.

16. At least a portion of the one or more first layers is made of Eu ２＋ and / or a low refractive index SiAlON layer doped with At least a portion of the one or more second layers is made of Eu ２＋ and / or a high refractive index SiAlON layer doped with at least a portion of the one or more second layers comprises an undoped high refractive index SiAlON layer; A luminescent glazing structure for greenhouses according to any one of claims 12 to 15.

17. At least a portion of the one or more first layers comprises an Al 3+ , N 3+ and Eu 2+ doped SiO 2 layer or an Eu 2+ doped SiAlO layer; and / or at least a portion of the one or more second layers comprises an AlN layer doped with Si 4+ , ​​O 2+ and Eu 2+ or a SiAlN layer doped with Eu 2+ ; and / or At least a portion of the one or more second layers comprises an undoped AlN layer or an undoped SiAlN layer. A luminescent glazing structure for greenhouses according to any one of claims 12 to 16.

18. The glass platelet includes a first (top) surface and a second (bottom) surface, wherein the Eu ２＋ One or more amorphous inorganic light-emitting thin film layers doped with Eu are provided on the first (top) surface, and the first (top) surface is further provided with the glass platelet and the Eu ２＋ 18. A greenhouse luminescent glazing structure according to any one of claims 1 to 17, which is textured to provide a light scattering interface between said one or more amorphous inorganic luminescent thin film layers doped with .

19. The greenhouse luminescent glazing structure of any one of claims 1 to 17, wherein the one or more amorphous inorganic luminescent thin film layers doped with Eu 2+ include an upper surface for receiving sunlight, the upper surface including a surface texture for providing a light scattering interface.

20. 20. A greenhouse luminescent glazing structure as claimed in claim 19, wherein the surface texture comprises patterned cones, pyramids, microlenses with average dimensions in the nanometer range (10 nm to 1000 nm) or micrometer range (1 to 1000 micrometers), or the form of the surface texture is in the form of a (semi)random texture with dimensions in the nanometer range or micrometer range, where the average dimensions are in the nanometer range (10 nm to 1000 nm) or micrometer range (1 to 1000 micrometers).

21. The greenhouse luminescent glazing structure according to any one of claims 1 to 20, wherein the glass platelet has a high haze, the high haze being higher than 70%, and / or the one or more amorphous inorganic luminescent thin film layers doped with Eu 2+ have a low haze, the low haze being lower than 20%.

22. A greenhouse comprising the greenhouse luminescent glazing structure according to any one of claims 1 to 21.

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