Apparatus for enhancing cooling via interaction with electromagnetic radiation and anti-Stokes fluorescence - Patents.com

Abstract

The present invention is an apparatus for enhancing cooling through interaction with electromagnetic radiation for optical cooling of an object and / or object surface, the apparatus comprising essentially three layers: a bottom layer comprised of a single or multi-layer material configured to emit IR radiation; a middle layer comprised of a single or multi-layer material configured to respond in anti-Stokes fluorescence upon absorption of electromagnetic radiation; and a top layer comprised of a single or multi-layer material configured to reflect selected spectral bands and / or enhance selected spectral bands of electromagnetic radiation transmittable to the middle layer.

Description

[Technical field]

[0001] The present invention relates to cooling of surfaces and objects, and more particularly to cooling of surfaces and objects via anti-Stokes fluorescence. [Background technology]

[0002] Fluorescent materials are known to absorb short wavelength radiation and emit long wavelength radiation with a specific emission shape described as the Stokes shift. The emission of such fluorescent materials can occur via the Stokes / anti-Stokes shift.

[0003] This well-known phenomenon of fluorescent materials is used in a variety of applications where bright colors are required, including biology and physics, as a non-destructive method for analysis and cell imaging.

[0004] Fluorescent materials are used in a variety of other applications including fluorescence resonance energy transfer (FRET), fluorescence recovery after photobleaching (FRAP), chemical sensors, optoelectronic devices, displays and the use of labeling agents for detection.

[0005] Fluorescent substances are characterized based on their quantum yield and fluorescence lifetime. Quantum yield can be described as the number of photons emitted relative to the number of photons absorbed. Possible values ​​of quantum yield range from 0 to 1. Lifetime is defined by the average time a molecule stays in an excited state before returning to the ground state.

[0006] Blackbody radiation of a material is the phenomenon by which the material loses part of its thermal energy through vibration-induced photon emission from its surface. At temperatures of about 300 K, blackbody radiation is emitted and absorbed by the material at wavelengths roughly between 5 and 50 μm, referred to as long wave, far infrared (LW-FIR) light.

[0007] Materials exposed to clear sky undergo cooling due to a net loss of LW-FIR photons. This cooling effect is due to two separate phenomena: (a) the existence of an atmospheric transparency band extending from 8 to 14 μm (the "atmospheric window"), through which ground photons can be emitted directly into space (the temperature of space is about 4 K, so the returning blackbody radiation is negligible); (b) the decrease in atmospheric temperature with height; since the temperature of the atmosphere can be significantly lower than that of the Earth's surface, ground blackbody photons are absorbed by the atmosphere from 14 μm onwards, and even fewer photons are re-emitted towards the surface due to the lower atmospheric temperature.

[0008] The total blackbody cooling of a material at 300K is 150 W / m 2 Flux values ​​of up to 100 nm can be achieved, which, when combined with high (>90%) solar reflectance, can result in surfaces being cooled below ambient temperature even during the day. Obstruction of the clear sky due to clouds, humidity, greenhouse gases, or other radiators reduces the actual radiative cooling flux.

[0009] Surface-air film coefficient in light wind: Estimated value for inner ring: 20W / K*m 2 Taking this, the actual radiation emitted from the surface is 20 W / m 2 It is possible to achieve sub-ambient cooling of 1 degree per second; this is equivalent to nearly all solar radiation (~1kW / m 2 ), and strongly emitting blackbody radiation through an atmospheric window primarily into space, and across the rest of the spectrum into the cooler atmosphere.

[0010] Laser cooling of solids is the phenomenon in which interaction with radiation causes effective cooling of solid materials. The idea was proposed by Pringsheim as early as 1929. However, the idea did not become reality until 1995, when laser cooling of solids, also called optical cooling of solids, was realized by Epstein et al., who managed to cool a solid by 0.3 K (Epstein 1995).

[0011] Laser cooling is a fast growing field, and the state of the art is the cooling of solids to extremely low temperatures of just 100 K (Melgaard 2016). In the solid phase of a material, a large amount of the thermal energy of this material is contained in the vibrational modes of the lattice. Thus, the vibrational motion of the particles is reduced, resulting in the cooling of the material. In analogy with quanta of light, the quanta of vibrational motion are usually called phonons.

[0012] The two main interactions that are important for laser cooling are (a) Stokes fluorescence / scattering, a process in which light interacts with matter such that photons are absorbed and re-emitted at lower energy (this process can sometimes be called luminescence down-conversion; the lost energy is converted to thermal energy in the solid, resulting in heating of the interacting material), and (b) anti-Stokes fluorescence / scattering (also called luminescence up-conversion), in which light interacts with matter in such a way that each photon is scattered with more energy than its initial energy. This energy is provided by phonons in the material, which leads to cooling of the material after equilibrium).

[0013] The physical principles of laser cooling in solids aim to achieve maximum anti-Stokes scattering and minimum Stokes scattering. Because the type of scattering is highly dependent on the wavelength of the light, lasers emitting light with a narrow range of wavelengths have traditionally been used in such studies.

[0014] Laser cooling using anti-Stokes fluorescence has been investigated and established for some time. Such cooling is achieved due to the emission of electromagnetic radiation (photons) with a higher average energy than that of the absorbed radiation. Effectively, heat is converted into light emitted from the matter.

[0015] Radiation emission with higher energy than the absorbed radiation can be modeled using a semiconductor with an energy band gap between the ground and excited levels and an energy level splitting between the two excited levels, where the band gap is an order of magnitude larger than the energy gap between these excited levels. Thermal equilibrium between the two excited levels results in a population of the higher excited level. Assuming there is no non-radiative decay of excited electrons at the higher excited level, photon emission occurs at a frequency (shorter wavelength) than that of the absorbed photons, resulting in net cooling.

[0016] At present, laser cooling of solids can be broadly categorized into two areas: laser cooling in ion-doped glasses or crystals, and laser cooling in semiconductors (bulk or confined, such as quantum well structures). One example of a use is in radiation-balanced lasers, where the pump wavelength is adjusted to compensate for laser heating by anti-Stokes fluorescent cooling.

[0017] Anti-Stokes solid-state coolers, also called optical coolers, based on the first two options above, are effective in reaching temperatures of only 80 K for rare-earth (RE) doped glasses and 55 K for direct bandgap semiconductors.

[0018] The main advantage of RE ions is the optically active 4f electrons that are shielded by filled 5s and 5p outer shells, which limits their interaction with the lattice surrounding the RE ion and suppresses non-radiative decay. Hosts with low phonon energy, e.g., fluoride glasses and crystals, can lower the non-radiative decay and increase the quantum efficiency. Laser induced cooling has been demonstrated in ZBLANP, ZBLAN, CNBZn and BIG, YAG and Y 2 SiO 5 ,BaY 2 F 8 , KPb 2 Cl 5 , K.G.d. 2 and K.Y. 2, YLF, etc., Ytterbium (Yb 3+ Laser-induced cooling has been observed in a wide variety of glasses and crystals doped with thulium (Tm 3+ ) doped ZBLANP and BaY 2 F 8 , and erbium (Er 3+ ) doped CNBZn and KPb 2 Cl 5 has also been observed.

[0019] Temperature Measurement – ​​IR Camera All objects emit radiation whose spectrum depends on the object's temperature. This radiation is called blackbody radiation because, in theory, a black body would absorb all of the radiation that falls on it and would therefore be "black". At temperatures near room temperature, the emitted radiation is mostly concentrated in the mid- and far-IR part of the spectrum, with wavelengths of about 10 micrometers. IR cameras contain detectors that measure the intensity of photons with these wavelengths. Assuming that the medium through which the photons propagate is transparent to these photons, these cameras make it possible to measure the temperature of a body from a distance. By measuring the intensity of the IR light, the temperature is easily calculated. In particular, temperature differences and evolutionary trends can be easily identified, even without calibration.

[0020] Temperature Measurement Method – Diode This method directly measures the temperature of a small diode that is thermally coupled to the sample you want to measure. When the temperature increases by a known amount, the voltage drop across the diode increases.

[0021] Temperature measurement methods – fluid regime The method looks at the regime within the fluid during light absorption and uses the direction of fluid movement in different areas of the container to determine slight temperature changes.

[0022] Newtonian Cooling Model

[0023] Newtonian cooling is a theory that describes the body's heat exchange with the environment. The theory assumes that the cooling rate depends on the temperature difference, giving an exponential solution. Using this solution with the addition of a stable heat / cooling source gives the following equation: TIFF0007678462000001.tif86127 Solar simulator A solar simulator is a device that emits light with a spectrum that closely matches the solar spectrum incident on the Earth (after atmospheric effects are taken into account). The following graph, produced by ASTM (American Society for Testing and Materials) and shown in Figure 1 (PRIOR ART), shows the intensity of light reaching the Earth (also called the solar spectrum) as a function of wavelength, with and without atmospheric absorption of light. In addition, the graph shows the theoretical spectrum expected by a black body with a temperature of 5778K, shown as a solid line, like the temperature of the surface of the Sun, with and without atmospheric absorption.

[0024] In the following we detail some basic models of anti-Stokes cooling in RE-doped glasses (four-level model) and semiconductors.

[0025] Four-level model of optical cooling As an example, Yb 3+ : We discuss the basic concept of laser cooling of solids using ZBLANP samples. 3+ The energy levels and major transitions in cm are shown in Figure 2A (prior art). The level system shown in Figure 2A can be approximated by a four-level system shown in Figure 2B (prior art).

[0026] In this four-level system, the ground state manifold (2F7 / 2) is represented by two energy levels with an energy separation δEg=E1-E0, corresponding to the level below (E0) and above (E1) of this manifold. The excited manifold (2F5 / 2) is represented by two energy levels with an energy separation δEex=E3-E2, corresponding to the level below (E2).

[0027] Figure 2A shows the Yb 3+ The energy levels and major transitions of

[0028] FIG. 2B shows a four-level energy model of optical cooling consisting of two sets of levels in the ground (0 and 1) and excited (2 and 3) manifolds.

[0029] Optical Cooling in Semiconductors Recent advances in semiconductor development and manufacturing have boosted interest in semiconductors as candidates for optical cooling. The essential difference between semiconductors and rare earth doped materials lies in the cooling cycle. In the case of RE doped glasses, the cooling transition occurs at localized donor ions in the host. In the case of semiconductors, the cooling cycle involves a transition between the extended valence and conduction bands of the direct band gap semiconductor. A laser photon with energy hνp creates a cold population of hole carriers. The carriers then heat up by absorbing phonons, followed by upconverted emission at hνf.

[0030] FIG. 3 (PRIOR ART) shows a schematic of the cooling cycle in a semiconductor with hνp absorbed energy prior to emission of upconverted luminescence photons at hνf.

[0031] The indistinguishable charge carriers in the Fermi-Dirac distribution allow the semiconductor to be cooled to lower temperatures than the RE-doped material. In fact, the highest energy level of the ground state manifold in the RE-doped system becomes less densely populated as soon as the temperature is lowered due to the Boltzmann distribution. The cooling cycle in the RE-doped host stops when the lattice temperature becomes comparable to the width of the ground state by a factor of the Boltzmann constant. Such a limit does not exist in undoped semiconductors. After theoretical estimations, temperatures as low as 10 K can be achieved in laser-cooled semiconductors. It has been shown that the lattice and the carriers can have different temperatures that vary in space and time.

[0032] Semiconductors are very promising materials for solid-state laser cooling, and their external quantum efficiency increases with decreasing temperature, but there are some problems that must be overcome to experimentally realize practical cooling of semiconductors, since the loss terms A and C decrease and the emissivity (B coefficient) increases inversely proportional to the temperature, and the above-mentioned loss terms A, B and C define the non-radiative, radiative and Auger rates of hole recombination. (1) The surface recombination rate needs to be reduced. Well-developed epitaxial growth techniques that can provide very low surface recombination rates (A<104 sec-1), such as metal-organic chemical vapor deposition (MOCVD), can be considered as a promising solution to this problem. In this case, an active layer of GaAs is sandwiched between two thin layers of AlGaAs or InGaP. These lattice-matched cladding layers simultaneously provide surface passivation and carrier confinement. (2) Parasitic background absorption needs to be reduced. This background absorption can be reduced during material preparation using well-developed epitaxial methods. Extraction efficiency can be enhanced if total internal reflection, which causes trapping and reabsorption of spontaneous emission, can be prevented. At present, sample purity is the main obstacle on the way to realizing practical laser cooling in semiconductors.

[0033] Candidate materials with energy level diagrams similar to those depicted in Figures 2A, 2B and 3 include semiconductors (excited across their bandgaps), rare earth or transition metal doped crystals and glasses, and polyatomic molecules of any phase (excited between vibrational levels).

[0034] FIG. 2A (prior art) shows RE doped glass, e.g., Yb 3+ :ZBLANP shows a four-level model of optical cooling. This diagram is originally relevant for laser cooling, but is equally relevant for broadband radiation.

[0035] FIG. 2B shows a specific calculation of the four-level model (units are cm −1 ).

[0036] Figure 3 is a schematic diagram of optical cooling in semiconductors. The upconversion of excited photons resulting from thermal equilibrium between adjacent excited energy levels leads to the emission of photons with higher energy than that of the absorbed photons. Thus, the optical cooling effect in semiconductor materials is realized by the absorption of phonons and the conversion of thermal energy into electromagnetic energy.

[0037] FIG. 4 (PRIOR ART) is an exemplary plot of the measured maximum ΔT (squared) and theoretically calculated temperature change curves (solid lines) normalized to pump power (K / mW) at different pump wavelengths at 290K. The solid line area corresponds to the cooling zone of the cadmium sulfide engineering material. The drop in temperature resulting from the absorption of photons with wavelengths between 505 nm and 560 nm can be clearly seen. When applied to broadband radiation in the present invention, by using the 505 nm to 560 nm spectral band extracted from solar radiation for cadmium sulfide, anti-Stokes fluorescence will be generated, resulting in effective cooling.

[0038] A variety of anti-Stokes-based cooling techniques are currently available that are based on the requirement for laser pumping and tuning to very specific emission wavelengths. Such techniques are efficient for certain applications where very low temperatures are required and monochromatic radiation is used.

[0039] An anti-Stokes-based cooling method applicable in conditions of temperature and non-monochromatic radiation was first introduced in 2018 by SolCold, the applicant of the present application (WO201820503).

[0040] In WO201820503, the applicant replaces the energy source, i.e. the laser pump, with a more naturally available broader spectrum radiation source, for example taken from the solar spectrum, and adjusts this spectral band to match the material exhibiting anti-Stokes fluorescence. More specifically, WO201820503 relates to a double or multi-layer apparatus or device for optical anti-Stokes cooling of an object surface. The apparatus comprises at least one lower layer configured to respond in anti-Stokes fluorescence upon absorption of electromagnetic radiation, and at least one upper layer superimposed on the lower layer configured to filter the electromagnetic radiation and transmit a selected spectral band of the electromagnetic radiation to the lower layer. The active cooling does not depend on the coherence of the radiation, which allows the use of non-coherent solar radiation as an active cooling input power source.

[0041] SUMMARY OF THE PRESENTLY PREFERRED EMBODIMENTS It is therefore an object of the present invention to improve the techniques for cooling larger scale objects and surfaces using the anti-Stokes effect.

[0042] More specifically, it is an object of the present invention to provide improved apparatus for anti-Stokes based cooling of objects and surfaces by using solar radiation, e.g., improved apparatus that enhances cooling mechanisms based on absorption of electromagnetic / solar radiation and anti-Stokes fluorescence. Summary of the Invention

[0043] The present invention relates to the enhancement of cooling mechanisms based on the absorption of non-coherent non-monochromatic electromagnetic / solar radiation and anti-Stokes fluorescence. The present invention relates to the fabrication and experimental measurements of solid composite materials made of highly fluorescent molecular and nanomaterials. These materials have been specifically investigated and found to be good, rather optional, candidates to be utilized as active anti-Stokes cooling layers in various embodiments of the present invention. Such layers can be induced to operate either by laser or solar radiation of specific wavelength ranges.

[0044] According to some embodiments of the present invention, therefore, Apparatus for enhancing a cooling mechanism based on the absorption of non-coherent non-monochromatic electromagnetic / solar radiation and anti-Stokes fluorescence at least one underlayer, said at least one underlayer being composed of a single or multiple layer material configured to reflect said electromagnetic radiation and / or emit IR radiation; at least one intermediate layer, the at least one intermediate layer being comprised of a single or multiple layer material configured to respond in anti-Stokes fluorescence upon absorption of electromagnetic radiation; and at least one upper layer, the at least one upper layer being comprised of a single or multiple layer material configured to filter the electromagnetic radiation and transmit selected spectral bands of the electromagnetic radiation that are transmissible to the intermediate layer and the lower layer, where the intermediate layer is configured to respond to one of the one or more selected spectral bands and where the lower layer is configured to respond to a second one of the one or more selected spectral bands, where the one and second spectral bands are the same or different from each other; An apparatus comprising: is provided.

[0045] According to some embodiments of the present invention, therefore, 1. An apparatus for enhancing electromagnetic radiation for optical cooling of an object and / or an object surface, comprising: at least one underlayer, said at least one underlayer being comprised of a single or multiple layer material configured to respond in anti-Stokes fluorescence upon absorption of electromagnetic radiation; and at least one upper layer, said at least one upper layer being comprised of a single or multiple layer material configured to enhance one or more selected spectral bands of said electromagnetic radiation transmittable to said lower layer; An apparatus comprising: is provided.

[0046] Further, according to some embodiments of the present invention, 1. An apparatus for enhancing electromagnetic radiation for optical cooling of an object and / or an object surface, comprising: at least one underlayer, said at least one underlayer being composed of a single or multiple layer material configured to reflect said electromagnetic radiation and / or emit IR radiation; at least one intermediate layer, the at least one intermediate layer being comprised of a single or multiple layer material configured to respond in anti-Stokes fluorescence upon absorption of electromagnetic radiation; and at least one top layer, said at least one top layer being comprised of a single or multiple layer material configured to enhance one or more selected spectral bands of said electromagnetic radiation transmittable to said intermediate layer; An apparatus comprising: is provided.

[0047] Furthermore, according to some embodiments of the present invention, the at least one top layer is configured to filter the electromagnetic radiation and to transmit one or more selected spectral bands of the electromagnetic radiation to the intermediate layer.

[0048] Furthermore, in accordance with some embodiments of the present invention, the device further comprises a filtering layer either above or below the at least one upper layer.

[0049] Furthermore, in accordance with some embodiments of the present invention, the underlayer is configured to reflect at least 50% of the electromagnetic radiation.

[0050] Furthermore, in accordance with some embodiments of the present invention, the device further comprises at least one layer configured to emit IR radiation.

[0051] Further, according to some embodiments of the present invention, the device further comprises at least one insulating layer. In some embodiments, the insulating layer is transparent to electromagnetic radiation. In still other embodiments, the insulating layer is a microporous membrane having pores with diameters smaller than 5 μm. In still other embodiments, the material from which the insulating layer is made is an ultra-low IR absorbing polymer and material selected from HDPE, nylon 6 and nylon 6,6 and iodide and bromide salts. In still other embodiments, nylon 6 or nylon 6,6 is a woven fabric. In still another embodiment, the insulating layer is air. In some embodiments of the present invention, the insulating layer is made of a material that is ITVOF (infrared transparent, visible light opaque). In still other embodiments, the thickness of the insulating layer ranges between millimeters and centimeters, for example, 1 millimeter to 10 centimeters, where the transparency to electromagnetic radiation, particularly IR radiation, decreases proportionally to its thickness. In some embodiments, the insulating layer is made of a material that is selectively transparent to electromagnetic radiation. In yet another embodiment, the electromagnetic radiation selective transparent material is selected from porous PTFE, PMMA (polymethylmethacrylate), PS (polystyrene) and germanium membrane. Preferably, the thickness of the porous PTFE membrane is in the range of 0.3-2 μm. In yet another embodiment, the germanium membrane is transparent between 8-13 μm. Furthermore, according to some embodiments of the present invention, the device further comprises at least one adhesive layer below the underlayer for attaching the device to an object to be cooled.

[0052] Furthermore, in accordance with some embodiments of the present invention, the device further comprises at least one upper mechanical layer for protecting the device against mechanical degradation.

[0053] Furthermore, according to some embodiments of the present invention, the layers are bonded together through an adhesive matrix domain.

[0054] Furthermore, according to some embodiments of the present invention, the at least one lower layer and / or the at least one upper layer and / or the at least one middle layer are provided within one or more membranes.

[0055] Furthermore, according to some embodiments of the present invention, the at least one layer is either continuous or discontinuous to allow communication frequencies to pass therethrough.

[0056] Further, according to some embodiments of the present invention, the electromagnetic radiation is non-coherent, non-monochromatic radiation having a broad spectral band, where the selected spectral band is sufficient for excitation of electrons from a ground energy state to an excited energy state in an active component within the underlayer.

[0057] Further, according to some embodiments of the present invention, the electromagnetic radiation is non-coherent, non-monochromatic radiation having a broad spectral band, where the selected spectral band is sufficient for excitation of electrons from a ground energy state to an excited energy state in an active component within the intermediate layer.

[0058] Furthermore, according to some embodiments of the present invention, the at least one top layer is composed of a fluorescent material having a QY of at least 80%.

[0059] Further, according to some embodiments of the present invention, the at least one overlayer is composed of at least one material selected from pyranine, perovskite, 11,3-bis[4-(dimethylamine)phenyl]-2,4-dihydroxycyclobutenediylium dihydroxide, bis(inner salt) [squarylium dye III], cyanine-3b (cyanine family), pyrromethene 567 (bodipy family), perylene, coumarin 6 (coumarin family), 9,10-bis(phenylethynyl)anthracene, 1,4-bis(5-phenyloxazol-2-yl)benzene (POPOP), perylene (PMI), perylene (PMI(OR)), perylene (PMI(OR)3), perylene (PDI), fluorescein, rhodamine 123, rhodamine 6G, rhodamine 101 inner salt, sulforhodamine 101, and rhodamine family and derivatives.

[0060] Further, according to some embodiments of the present invention, at least one underlayer comprises continuous or porous PTFE (polytetrafluoroethylene), PDMS (polydimethylsiloxane), HDPE (high density polyethylene), PS (polystyrene), silica, germania, alumina, titania, barium sulfate, or nano- or particulates thereof, wherein said nano- or particulates are free-standing or embedded within a film, matrix or membrane, to reflect selected wavelength bands of solar radiation.

[0061] In yet some other embodiments of the invention, the pore diameter of the bottom solar-reflective layer is in the range of 0.2 to 2 microns. In still other embodiments of the invention, the solar radiation-reflective bottom layer comprises particulates of the same diameter of such pores, i.e., 0.2-2 microns, where these particulates are uniformly distributed in the volume of the layer.

[0062] For particles in the solar radiation reflective layer, radiation scattering, i.e. scattering events, occur at the particle boundaries. Thus, there is a trade-off between the particle size and the number of scattering events determined by the number of particles in the solar reflective layer film. Therefore, optimizing reflection requires a balance between the ideal particle size as individual scatterers and the number and distribution of particles in the film.

[0063] Furthermore, according to some embodiments of the present invention, the solar radiation reflective layer is a film having a thickness in the range of 1 to 1000 microns.

[0064] Furthermore, according to some embodiments of the present invention, the at least one sub-layer is composed of a fluorescent material having a QY of at least 90%.

[0065] Further, according to some embodiments of the present invention, the at least one underlayer is composed of at least one material selected from cadmium sulfide, gallium arsenide (GaAs) quantum wells, ytterbium doped yttrium lithium fluoride (Yb:YLF) crystals, ytterbium doped tungsten crystals (Yb:KGW), fluorozirconate glass doped with 1 wt% Yb3+ (ZBLANP), 9Be+, cesium, CdS / ZnS, perovskite, pyranine, 20 BPEA, rhodamine 101 (xanthine family), and pyrromethene 567 (bodipy family).

[0066] Furthermore, according to some embodiments of the present invention, the at least one intermediate layer is composed of a fluorescent material having a QY of at least 90%.

[0067] Furthermore, according to some embodiments of the present invention, the at least one intermediate layer is composed of at least one material selected from cadmium sulfide, gallium arsenide (GaAs) quantum wells, ytterbium doped yttrium lithium fluoride (Yb:YLF) crystals, ytterbium doped tungsten crystals (Yb:KGW), fluorozirconate glass doped with 1 wt% Yb3+ (ZBLANP), 9Be+, cesium, CdS / ZnS, perovskite, pyranine, BPEA, rhodamine 101 (xanthine family), and pyrromethene 567 (bodipy family).

[0068] Further, according to some embodiments of the present invention, the at least one underlayer is selected from the group consisting of continuous or porous PTFE or PTFE nano- or particulate, continuous or porous PDMS or PDMS nano- or particulate, continuous or porous SiO 2 or SiO 2 Nano or fine particles, alumina, TiO 2 , BaSO 4 , metal, SiO 2 , continuous or porous etched ceramics such as Si polymers, etc. Furthermore, according to some embodiments of the present invention, the at least one underlayer is made of a porous material with strong optical activity in the LW-FIR region.

[0069] Furthermore, according to some embodiments of the present invention, the underlayer has a continuous PDMS film for emission of blackbody radiation within the atmospheric window of 8 to 14 μm. In one particular embodiment, the thickness of the continuous PDMS film in the underlayer is in the range between 3.5 μm and 5 μm. In yet another particular embodiment, the thickness of the continuous PDMS film in the underlayer is 4 μm.

[0070] In another embodiment of the invention, the PDMS membrane in the underlayer is porous with a total mass approximately equal to the mass of a continuous PDMS membrane having a thickness in the range of 3.5 to 5 μm, preferably 4 μm thick. In yet another embodiment of the invention, the diameter of the pores in the porous PDMS membrane is in the range of 8-14 μm, where the pores are uniformly distributed within the volume of the membrane.

[0071] In yet another embodiment of the invention, the PDMS film in the underlayer further comprises electromagnetic radiation emitters at a wavelength of 11 μm due to the relatively low emission of PDMS at this wavelength. In some embodiments, these emitters include SiC, BaSO 4 and ZnO. In yet other embodiments, the emitters are provided as particles having a relatively small diameter of about 0.3 μm. In yet other embodiments, the emitters are provided as particles having a relatively large diameter in the range of 8-13 μm.

[0072] Furthermore, according to some embodiments of the present invention, the device is exposed to the sun and / or is located under a transparent object and / or is located under a perforated object.

[0073] Furthermore, according to some embodiments of the present invention, the device cools solids, liquids and vapors.

[0074] Furthermore, in accordance with some embodiments of the present invention, the device is provided in a paint.

[0075] Furthermore, in accordance with some embodiments of the present invention, the device is incorporated into a textile.

[0076] Further, according to some embodiments of the present invention, the at least one upper layer is incorporated into an outer surface of the fibers of the textile, the at least one lower layer is incorporated into a core of the fibers, and the at least one intermediate layer is incorporated between the outer surface of the fibers and the core of the fibers.

[0077] Further, according to some embodiments of the present invention, the device has physical and chemical compatibility with surfaces of different materials. [Brief description of the drawings]

[0078] [Figure 1] (PRIOR ART) Shows the spectrum of the sun, modeled as a blackbody (shown as a solid line) with a temperature of 5778 K, with and without atmospheric absorption.

[0079] [Figure 2A] (Prior Art) Shows a four-level model of optical cooling.

[0080] [Figure 2B] (PRIOR ART) An example of the four-level model of optical cooling.

[0081] [Diagram 3] (Prior Art) Shows a semiconductor model of optical cooling.

[0082] [Figure 4] 1 (PRIOR ART) shows plots of calculated temperature change and optical cooling.

[0083] [Figure 5A] 1 illustrates a first apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence, according to some embodiments of the present invention.

[0084] [Figure 5B]1 illustrates a second apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence, according to some embodiments of the present invention.

[0085] [Figure 5C] 13 illustrates a third apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence, according to some embodiments of the present invention.

[0086] [Figure 5D] FIG. 1 is a schematic diagram illustrating various layers and their possible locations within an apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence, according to some embodiments of the present invention.

[0087] [Figure 5E] FIG. 1 is a schematic diagram illustrating an apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence, comprising multiple layers, in accordance with some embodiments of the present invention.

[0088] [Figure 6] 1 is an intensity as a function of time plot showing the Stokes shift of a pyranine dye that enhances the solar spectrum.

[0089] [Figure 7] 1 illustrates diagrammatically one particular implementation of an apparatus for optical cooling of objects and / or object surfaces according to the present invention;

[0090] [Figure 8] 1 shows the results of cooling experiments carried out outdoors with a device for optical cooling of objects and / or object surfaces.

[0091] [Figure 9] 1 shows the results of cooling experiments carried out indoors using a device for optical cooling of objects and / or object surfaces.

[0092] [Figure 10] The present invention is modeled in cooling using anti-Stokes fluorescence in a multi-layer device with insulation to enhance electromagnetic radiation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0093] The present invention relates to an apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence. More specifically, the present invention relates to a multi-layer apparatus for enhancing electromagnetic radiation and optical anti-Stokes and radiative cooling of an object surface via a material responsive to broadband solar radiation.

[0094] According to some embodiments of the present invention, an apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence 100 extracts and enhances selected spectral bands from solar radiation for anti-Stokes fluorescence cooling, thus generating a cooling effect in the object on which it is superimposed by emitting anti-Stokes fluorescence.

[0095] FIG. 5A illustrates a first apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence 100, according to some embodiments of the present invention.

[0096] According to some embodiments of the present invention, a first apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence 100 includes: (a) at least one sublayer 102 that is an active cooling layer comprised of a single or multiple layer material configured to respond in anti-Stokes fluorescence upon absorption of electromagnetic radiation; and (b) at least one upper layer 104 which is an enhanced filter layer; At least one upper layer 104 is comprised of a single or multiple layers of material configured to enhance the electromagnetic radiation transmitted to the lower layer 102.

[0097] FIG. 5B illustrates a second apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence 200, according to some embodiments of the present invention.

[0098] According to some embodiments of the present invention, a second apparatus for enhancing electromagnetic radiation via anti-Stokes fluorescence 200 and cooling of an object and / or object surface includes: (a) at least one underlayer 202 that is a reflective layer with or without IR emission, comprising a single or multiple layer material configured to reflect at least 50% of radiation and to emit IR radiation, e.g., may function as a reflector that reflects at least 50% of radiation plus IR emission; (b) at least one intermediate layer 204 that is an active cooling layer comprised of a single or multiple layer material configured to respond in anti-Stokes fluorescence upon absorption of electromagnetic radiation; and (c) at least one upper layer 206 that is an enhancing filter layer, the at least one upper layer 206 being composed of a single or multiple layers of material configured to enhance the electromagnetic radiation transmitted to the intermediate layer 204; It may comprise:

[0099] According to some embodiments of the present invention, the apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence 100, 200 may further include filtering capabilities, i.e., filtering the radiation spectrum and enhancing a spectral window using a Stokes shift, providing a multi-layer structure to transmit selected bands to the layer exhibiting anti-Stokes fluorescence.

[0100] According to some embodiments of the present invention, the heat generated by the Stokes shift in the at least one upper layer 104, 206 may be less than the heat cooled by the anti-Stokes fluorescence in the lower layer 102 / middle layer 204. That is, the cooling effect in the lower layer 102 / middle layer 204 may exceed the heating effect in the at least one upper layer 104, 206, since the lower layer 102 / middle layer 204 may use not only enhanced electromagnetic radiation originally outside the spectral window of the anti-Stokes fluorescence, but also filtered electromagnetic radiation originally within the spectral window. Furthermore, according to some embodiments of the present invention, not all of the heat generated by the Stokes shift in the at least one upper layer 104, 206 penetrates into the lower layer 102 / middle layer 204, since part of the heat dissipates to the surroundings.

[0101] According to some embodiments of the present invention, at least one upper layer 104, 206 may filter electromagnetic radiation to transmit selected spectral bands of electromagnetic radiation transmitted to the lower layer 102 / middle layer 204. At least one upper layer 104, 206 may include filtering means to selectively reflect light particles such as UV and some visible light that are not useful for cooling. Filtering of light particles that are not useful for cooling prevents heating and degradation of more sensitive layers below this layer. The filtering layer is therefore the outermost exposed to the light source (sun).

[0102] According to some embodiments of the present invention, the filtering and enhancing capabilities of at least one layer may shield the object and / or object surface from unwanted absorbed radiation, and may actually make the cooling effect more efficient by increasing the input to output ratio of radiation via enhancement of the spectral band transmitted to the lower layer 102 / middle layer 204.

[0103] At least one filtering layer filters the radiation by reflecting a portion of it back to the atmosphere, and at least one enhancement layer enhances the spectral window incidence by shifting a portion of the radiation to a particular band. At least one enhancement layer has embedded therein a Stokes shifter for shifting photons from high to low frequencies to increase the photon flux in a desired band for anti-Stokes cooling, and transmitting a selected range of wavelengths including the enhanced band to the active cooling layer, e.g., bottom layer 102 / middle layer 204.

[0104] For example, the at least one enhancement layer may convert unwanted blue light to green light, and thus the at least one enhancement layer may enhance natural green light with the converted blue light.

[0105] Thus, according to some embodiments of the present invention, the at least one filtering layer may be located either above or below the at least one enhancement layer. Alternatively, at least one layer, i.e., the at least one upper layer, may have filtering and enhancement capabilities.

[0106] As mentioned above, at least one upper layer 104 / 206 may have filtering capabilities. Alternatively, additional layers with filtering capabilities may be implemented above / below the at least one upper layer 104 / 206.

[0107] Thus, according to some embodiments of the present invention, the role of the at least one upper layer 104, 206 is three-fold, since the at least one upper layer 104, 206 may (a) filter the radiation spectrum by reflecting part of it back to the atmosphere and / or by blocking it via absorption or in any other manner, (b) enhance the spectral window incidence by shifting part of the radiation to a particular band (Stokes shift to shorter wavelengths), and (c) transmit a selected range of wavelengths including the enhanced band to the active cooling layer, e.g., the lower layer 102 / middle layer 204.

[0108] According to some embodiments of the present invention, at least one lower layer 102 / middle layer 204, e.g., at least one anti-Stokes layer, may be located below at least one upper layer 104, 206, i.e., below at least one enhancement layer (with / without filtering capability).

[0109] At least one lower layer 102 / middle layer 204 absorbs a selected portion of the spectrum (e.g., the band transmitted through at least one upper layer 104, 206) and loses thermal energy through photon upconversion, i.e., using anti-Stokes effect active cooling, shifting the wavelength of the absorbed band to the shorter wavelength range.

[0110] It should be noted that the cooling effect is enhanced and improved by enhancing the spectral window by embedding a Stokes-shifted material through at least one top layer (enhancement layer) 104, 206. According to some embodiments, the cooling effect due to the anti-Stokes fluorescence of at least one bottom layer 102 / middle layer 204 may exceed the heating effect due to the Stokes shift of at least one top layer (enhancement layer) 104, 206.

[0111] It should be noted that using the anti-Stokes effect at a frequency range (within a spectral band) rather than just one does not change the possibility of performing cooling due to the presence of anti-Stokes reactions across the entire spectral band.

[0112] According to some embodiments of the present invention, active cooling does not rely on the coherence of radiation, which allows the use of incoherent solar radiation as an active cooling input source. This spectral bandwidth may be between 10 nm and 200 nm.

[0113] As explained above, the second device for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence 200 may comprise at least one underlayer 202 that is a reflective layer with IR emission.

[0114] According to some embodiments of the present invention, at least one lower layer 202 accepts the band transmitted through the middle layer 204 and reflects back a large portion of the band with additional IR emission. Such IR emission passes through multiple layers and exits to the atmosphere without being absorbed, thus enhancing cooling. That is, the IR emission may dissipate heat to the surroundings, which is not absorbed within the device. In some embodiments, the IR emission may help the device to dissipate heat that cannot be dissipated by the active cooling layer alone.

[0115] At least one lower layer 202, a reflective layer, may be located below all layers as it reflects unused light particles and / or light particles that have "leaked" through at least one upper layer 104, 206. In some embodiments, the reflective layer may also enhance the cooling effect as unused light particles and / or light particles that have "leaked" through at least one upper layer 104, 206 may have another opportunity to be reflected back to the at least one upper layer 104, 206 and used for anti-Stokes fluorescence.

[0116] It should be noted that in the case of electronic devices, at least one bottom layer 202 may not be used since it includes a metal, such as aluminum, which may block communication frequencies.

[0117] According to some embodiments of the present invention, at least one underlayer 202 may be made of porous PDMS or other porous material with strong optical activity in the LW-FIR region (LW-FIR emission) to increase the degree of cooling.

[0118] FIG. 5C illustrates a third apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence 300, according to some embodiments of the present invention.

[0119] The third device may include at least one lower layer 302 that is a reflective layer, at least one first intermediate layer 304 with IR cooling, at least one second intermediate layer 306 that is an active cooling layer composed of a single or multiple layer material configured to respond in anti-Stokes fluorescence upon absorption of electromagnetic radiation, and at least one upper layer 308 that is an enhancement filter layer. To enhance cooling via electromagnetic radiation transmitted to the at least one intermediate layer 304, 306, the at least one upper layer 308 is composed of a single or multiple layer material configured to enhance emission within a desired spectral band.

[0120] According to some embodiments of the present invention, an apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence 100, 200, 300 may comprise additional layers, such as an insulating layer, as seen in Figures 5D and 5E.

[0121] FIG. 5D is a schematic diagram illustrating various layers and possible locations of each layer within an apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence according to some embodiments of the present invention.

[0122] As can be seen in this figure, at least one IR radiative cooling layer 502 may be located at one / multiple locations and may be made from a variety of materials.

[0123] As can be seen in this figure, the at least one IR radiative cooling layer 502 may be located in various locations, i.e., above / below at least one upper layer 104, 206, 308, above / below at least one lower layer 102, at least one intermediate layer 204, at least one first intermediate layer 304 and at least one second intermediate layer 306, and / or above / below the lower layers 202, 302.

[0124] At least one RC (radiative cooling) layer 502 can function with or without at least one upper layer 104, 206, 308. For example, if an interior coating is installed on the windshield of a vehicle, the windshield (glass) can be at least one IR radiative cooling layer 502. The material of the IR radiative cooling layer 502 can be, for example, PDMS. The IR radiative cooling layer 502 operates in the infrared spectrum 8 microns to 12 microns. Therefore, the IR radiative cooling layer 502 can enhance the cooling effect.

[0125] As can be seen in this figure, at least one or more insulating layers 504 may be located below at least one of the upper layers 104, 206, 308 to prevent heat from penetrating into at least one of the lower layer 102, the middle layer 204, the first middle layer 304, and the second middle layer 306.

[0126] At least one insulating layer 504 may be located between at least one underlayer 102, 202, 302 and the surface of the object to be cooled. At least one insulating layer 504 may be made of materials that are HDPE, nylon 6 and nylon 6,6, iodide and bromide salts, and ITVOF. At least one insulating layer 504 may be transparent so that photons for anti-Stokes shift can pass through at least one insulating layer 504 and reach the active cooling layer used for anti-Stokes fluorescence.

[0127] The cooling effect of the active cooling layer can be achieved properly since the cooling effect is achieved by the emission of photons, not the emission of heat.

[0128] 10 is a schematic model of a multi-layer device of the present invention for cooling using enhanced anti-Stokes fluorescence of incident electromagnetic radiation. For convenience of modeling, a semiconductor electrical configuration is used having a band gap between the valence and conduction bands suitable for absorbing a selected bandwidth of electromagnetic radiation from a broadband source (e.g., the sun). At a selected wavelength λ in is the valence band E 1and the base energy level E in one of the conduction bands. 2 Excitation energy level E higher than 3 The energy difference between 3 -E 1 The excess of incident electromagnetic energy corresponds to phonon q heat =E 3 -E 2 and the outgoing radiation λ is Stokes fluorescence out is the band gap E 2 -E 1 This results in thermal emission to the upper layer and a red-shift of the incident radiation. The incident radiation is thus enhanced by providing photons with a wavelength suitable for producing a cooling effect in the lower layer. The electrons in the cooling layer emit an outgoing electromagnetic radiation λ out , and absorbs additional thermal energy, phonons, in the valence band. The annihilated phonons cause a cooling effect, q cool =E' 2 -E' 1 (E' 2 : The highest ground level of the valence band; E' 1 :E' 2 (lower energy level than the conduction band λ out,Stokes ~1(E' 3 -E' 2 ), providing additional energy for excitation to E' 3 is the lowest energy level of the conduction band. Excited electrons in the conduction band are reduced below the ground state, which causes a blue shift of the incident radiation, λ, at the cooling layer in anti-Stokes fluorescence. out,Anti-Stokes ~1(E' 3 -E' 2 ) is induced. In some embodiments of the present invention, the thermal energy generated in the enhancement top layer is dissipated to the surroundings or counteracts the absorption of phonons in the cooling layer. Alternatively, in some embodiments of the present invention, a thermal insulating layer is disposed between the enhancement and cooling layers, as shown in Figure 10. This insulating layer is transparent to the outgoing electromagnetic radiation from the enhancement layer, thereby allowing the red-shifted photons to pass through the cooling layer.

[0129] According to some embodiments of the present invention, the apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence 100, 200, 300 may comprise additional layers, such as an adhesive / magnetic layer below the lower layer for attaching the apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence 100, 200, 300 to the object to be cooled.

[0130] Additionally, the device for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence 100, 200, 300 may comprise additional layers, at least one upper mechanical layer, to prevent damage such as physical, chemical or electrical damage and minimize degradation of the device 100, 200, 300 over time and to thermally and electrically isolate at least one lower layer 102, intermediate layer 204, first intermediate layer 304, second intermediate layer 306 from environmental influences.

[0131] According to some embodiments of the present invention, the at least one upper mechanical layer may prevent scuffs and scratches, the at least one upper mechanical layer may prevent static electricity and dust accumulation, facilitate easy cleaning, etc. The at least one upper mechanical layer may be made of polyurethane. The at least one upper mechanical layer may be transparent so that photons for the anti-Stokes shift can pass through the at least one upper mechanical layer to reach the active cooling layer.

[0132] FIG. 5E is a schematic diagram illustrating an apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence 400, comprising multiple layers, according to some embodiments of the present invention.

[0133] As can be seen in this figure, in addition to the two layers required for cooling, there is also, as described in FIG. 5A, namely (a) at least one active cooling layer composed of a single or multi-layer material configured to respond in anti-Stokes fluorescence upon absorption of electromagnetic radiation, and (b) at least one upper layer configured to enhance the electromagnetic radiation transmitted to the active cooling layer.

[0134] The apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence 400 may include multiple additional layers, such as a back reflector layer 402, a radiative cooling layer 404, an anti-Stokes layer 406, a transparent thermal barrier 408, a Stokes filter 410, and a UV filter 412 to enhance and maximize cooling.

[0135] According to some embodiments of the present invention, the material of the UV filter 412 may be, for example, 9Be+. The UV filter 412 operates at 300 nm. Therefore, the UV filter 412 may enhance the cooling effect.

[0136] It should be noted that the device for enhancing electromagnetic radiation and cooling of objects and / or object surfaces via anti-Stokes fluorescence 100, 200, 300, 400 may comprise multiple layers, each layer having one or more activities. For example, the device may comprise a first layer having filtering means and a second layer having enhancing means. Alternatively, the device may comprise a single layer having both filtering and enhancing means. According to some embodiments of the present invention, the multiple layers may be bonded to each other through an adhesive matrix domain. The role of the adhesive matrix is ​​therefore two-fold: (a) to attach the layers to each other and (b) to protect the layers from environmental damage (such as moisture).

[0137] According to some embodiments of the present invention, this matrix can be used to attach these layers via heat or any other means to the surface of the object to be cooled.

[0138] According to some embodiments of the present invention, an apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence 100, 200, 300, 400 may comprise semiconductor materials for wide band gap anti-Stokes cooling under broad spectrum solar radiation, and / or RE doped synthetic materials for obtaining anti-Stokes fluorescence using a wide range of solar radiation, and / or organic dyes and quantum dots are used for obtaining anti-Stokes fluorescence using a wide range of solar radiation.

[0139] According to some embodiments of the present invention, multiple layers of devices for enhancing electromagnetic radiation via anti-Stokes fluorescence 100, 200, 300, 400 and cooling of objects and / or object surfaces are provided within the membrane.

[0140] According to some embodiments of the present invention, various materials have been investigated, some of which have been found to be good candidates for use as active anti-Stokes cooling layers, and to operate with either laser or solar radiation in specific wavelength ranges, are described as follows:

[0141] 6 is an intensity as a function of time plot showing the Stokes shift of the solar spectrum enhancing pyranine dye 602. Seen in this figure is the enhancement of the spectral window between 525 nm and 600 nm.

[0142] 7 shows a schematic of one particular implementation of an apparatus for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence 100, 200, 300, 400 of the present invention. As can be seen in this figure, the shell is an upper layer 104, 206, 308, 412 that filters and enhances the incident radiation into a desired wavelength range, as shown in FIG.

[0143] The core of the device for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence 100, 200, 300, 400 is an underlayer 202, 302, 402 that is reflective in IR emission, between which is an active material fluorescent layer 102, 204, 304, 306, 406 that receives and absorbs radiation within a filtered wavelength range and responds by emitting radiation in the anti-Stokes fluorescence.

[0144] In one particular example, the structure of the device for enhancing electromagnetic radiation and cooling of objects and / or object surfaces via anti-Stokes fluorescence 100, 200, 300, 400 may be used in textiles for any application to cool objects, bodies and spaces by covering them with a protective cooling textile or shielding them from heat sources. Specific applications of such coverings and shields are selected from clothing, drapes, shades, curtains, bags, camping equipment and food cooler covers, etc.

[0145] Figure 8 shows the results of cooling experiments carried out outdoors using the device for enhancing electromagnetic radiation and cooling of objects and / or object surfaces via anti-Stokes fluorescence 100, 200, 300, 400. The cooling film, consisting of a reflective layer, a radiation enhancing layer and an active cooling layer, was measured on a summer day with an air temperature of 33°C and a relative humidity of 50 percent.

[0146] As can be seen in this figure, the temperature was reduced by 3°C by electromagnetic radiation via anti-Stokes fluorescence 100, 200, 300, 400 and a device for enhancing cooling of the object and / or object surface.

[0147] FIG. 9 shows the results of a cooling experiment carried out with the device for enhancing electromagnetic radiation and cooling of objects and / or object surfaces via anti-Stokes fluorescence indoors, where the air temperature was 22° C.

[0148] In this experiment, a sample in liquid form was illuminated with 100mW of light, which was filtered and enhanced by a device to enhance electromagnetic radiation via anti-Stokes fluorescence and cooling of the object and / or its surface.

[0149] It should be noted that the anti-Stokes fluorescence cooling experiments described in this invention can be performed without any additional components other than electrical input, moving parts, gases, liquids, and devices for enhancing electromagnetic radiation and cooling of objects and / or object surfaces via anti-Stokes fluorescence 100, 200, 300, 400 defined above.

[0150] Perovskite Perovskites have the common formula A 1 a B 2 b X cIt is an optoelectronic material with a high photonics potential. Loredana Prodesescu et al. (Nano Lett., 2015, 15, 3692-3696) developed inorganic perovskites using cheap and effective materials to obtain stable and luminescent QDs (quantum dots). These intrinsic materials can be modulated with different quantum size effects and bandgaps. They operate in the entire visible spectral range from 400 to 700 nm. These quantum dots are characterized by a narrow emission linewidth of 12 to 42 nm and have an excellent quantum yield close to 100%. 8-Hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt fluorescent molecule refers to pyranine and all of its substituted and derivatives. This molecule is well known and is used as a tracer and fluorescent pH indicator. Its fluorescent emission is strongly dependent on its pH. The excitation range of "pyranine" is between 400 and 460 nm. 9,10-Bis(phenylethynyl)anthracene refers to BPEA and all of its substituted and derivatives. BPEA is a well-known fluorescent aromatic hydrocarbon fluorophore with a highly efficient quantum yield. In addition, BPEA has unique optical and electronic features that make it a promising material for solar cells, light-emitting diodes, etc. Its optical properties in the visible range appear from 335 to 500 nm. 9H-xanthene, 10H-9-oxanthracene refers to the xanthine family and all of its substituted and derivatives. Xanthine dyes represent a wide class of compounds. Some may exhibit the fluorescent properties studied here. These well-known types of compounds are ubiquitous in the human body and are closely related to the DNA bases guanine and adenine. These types of dyes can form supramolecular structures that exhibit unique chemical and physical properties. It has vast UV-visible absorption that can range from 300 to 700 nm.

[0151] Diketocyclobutenediol refers to squaraine dyes and all of its derivatives and substitutions. Squaraine dyes are a class of organic compounds that exhibit a narrow absorption band in the near infrared, ranging from 700 to 1500 nm. In addition to a unique and strong absorption band, squaraine dyes also exhibit high molar absorption coefficients and good photoconductivity and photostability. Bis(3-methylindole)-2-pyridylmethane refers to dipyrromethane and all of its substitutions and derivatives. They are used as intermediates in the synthesis of fluorescent compounds. Usually, this synthesis is by acid-catalyzed condensation. Bodipy is a fluorescent compound synthesized from the dipyrromethane family. Bodipy has the same nucleus as dipyrromethane, but with the addition of two fluorenes and the subtraction of two hydrogens. These bodipy dyes are used to label amino acids and nucleotides. They have a UV-visible absorption range from 500 to 750 nm.

[0152] Tetramethylindo(di)-carbocyanine refers to all of the cyanine fluorophores and their substitutes and derivatives. These dyes are quaternary ammonium salts and are used in solar energy conversion and pH sensing. They are also used in labeling proteins, antibodies and peptides. They have a UV-Visible absorption spectral range from 400 to 900 nm.

[0153] The results of an experiment in which the solar spectrum is passed through a pyranine layer and measured with a spectrometer are shown in Figure 6.

[0154] Specific non-limiting examples of compounds that can be part of an apparatus for enhancing electromagnetic radiation and cooling of objects and / or object surfaces via anti-Stokes fluorescence 100, 200, 300, 400, according to some embodiments of the present invention, are listed below.

[0155] Table I shows examples of compounds that may be used to form the bottom layer 102 / middle layer 204 , 306 , 406 of a device for cooling an object and / or object surface via anti-Stokes fluorescence 100 , 200 , 300 , 400 .

[0156] [Table I] [Table 1] Table I details the spectral bandwidth required for each of the materials shown in this table to obtain anti-Stokes fluorescence, and the radiation absorption-to-emission conversion efficiency.

[0157] It should be noted that any fluorescent material with a QY (quantum yield) of 90% or higher can be used to create anti-Stokes cooling of an object and / or object surface via anti-Stokes fluorescence 100, 200, 300, 400.

[0158] In some embodiments, the at least one active cooling layer may include more than two layers, and each of these layers may be made of a different active cooling material in Table I. Because the spectral bands of the active cooling materials vary from material to material, the material of each layer may be selected such that the spectral bands may be, for example, perovskite, CdS or ZnS with fluorescence in the 610-660 nm range and GaAs quantum wells in the 600-660 nm fluorescence range.

[0159] Table II shows examples of compounds that may be used to form the upper layer 104, 206, 308, 412 of a device for enhancing electromagnetic radiation such that the layer below the lower layer 102 / middle layer 204, 306, 406 (see Table 1) results in cooling of an object and / or object surface via anti-Stokes fluorescence 100, 200, 300, 400.

[0160] According to some embodiments of the present invention, the filter layer may include compounds detailed in Table II to provide enhancement of the band width incident on the active layer.

[0161] [Table II] [Table 2] It should be noted that any fluorescent material having a QY of 80% or higher may be used to form the upper layer 104, 206, 308, 412 of the device for enhancing electromagnetic radiation and cooling of the object and / or object surface via anti-Stokes fluorescence 100, 200, 300, 400.

[0162] The material of the active cooling layer and the material of the enhancement filter layer may be selected interchangeably. Compared with the spectral band of the active cooling layer that fluoresces at 300 nm, the spectral band of the enhancement filter layer may absorb radiation in the range of 400-460 nm and fluoresce in the range of 525-600 nm (see FIG. 6). Each of the absorption and fluorescence wavelength ranges of pyranine may be broad or narrow and may overlap with each other depending on different parameters of the pyranine-containing layer (e.g., pyranine concentration).

[0163] Table III provides examples of compounds that may be used to form the underlayer 202, 302, 402 of a device for enhancing electromagnetic radiation via anti-Stokes fluorescence 200, 300, 400 and cooling of an object and / or object surface.

[0164] [Table III] [Table 3] Table III details some of the possible materials for the underlayer that are highly reflective in the IR and have greater than 90% emissivity.

[0165] It should be noted that all layers may be continuous / discontinuous, for example, may include openings to allow passage of multiple communication frequencies.

[0166] According to some embodiments, that the coating, e.g., the device for enhancing electromagnetic radiation via anti-Stokes fluorescent 100, 200, 300, 400 and cooling of the object and / or object surface can be exposed to the sun; The device 100, 200, 300, 400 is placed under a transparent object (such as glass or water) or a transparent coating exposed to the sun. Subject to the above, The apparatus for enhancing electromagnetic radiation via anti-Stokes fluorescence 100, 200, 300, 400 and cooling of objects and / or object surfaces may be used to cool a variety of objects.

[0167] The device 100, 200, 300, 400 is located beneath a perforated object such as a mesh that is exposed to the sun. According to some embodiments of the present invention, the device for enhancing electromagnetic radiation and cooling of an object and / or object surface via the anti-Stokes fluorescent 100, 200, 300, 400 of the present invention may be suitable for small and large scales, and in fact for any object having a surface onto which a layer material may be deposited or overlaid, such as roofs, walls, automobiles, boats, tents, clothing, etc.

[0168] According to some embodiments of the present invention, the apparatus for enhancing electromagnetic radiation and cooling of objects and / or object surfaces via anti-Stokes fluorescence 100, 200, 300, 400 may be implemented in paints, fabrics, and the like.

[0169] The coating, which is comprised of a device for enhancing electromagnetic radiation and cooling of an object and / or object surface via anti-Stokes fluorescence 100, 200, 300, 400, can be applicable to different materials and surfaces, such as concrete, fabric and glass windows.

[0170] That is, the techniques for producing such multi-layer paints, i.e., paints comprised of devices for enhancing electromagnetic radiation and cooling of objects and / or object surfaces via anti-Stokes fluorescence 100, 200 having physical and chemical compatibility with surfaces of different materials, have proven substantially efficient for multiple applications that would not otherwise enjoy any anti-Stokes fluorescence based cooling.

[0171] According to some embodiments of the present invention, the materials selected to make such multi-layer paints are not only efficient for cooling, but also provide long-term compatibility with the surfaces they come into contact with. Such multi-layer paints have demonstrated long-term activity when layered on surfaces or embedded in objects made of different materials.

[0172] According to some embodiments of the present invention, at least one top, middle and bottom layer may be incorporated into the woven fabric, with at least one top layer being incorporated into the outer surface of the fibers of the woven fabric, the bottom layer being incorporated into the core of the fibers, and the middle layer being therebetween.

[0173] According to some embodiments of the present invention, the apparatus for enhancing electromagnetic radiation via anti-Stokes fluorescence 100, 200, 300, 400 and cooling of objects and / or object surfaces may cool solids such as metals (e.g., vehicles), ceramics, glass (e.g., glass in buildings), membranes and fabrics (tents / fabrics / insulation for shipping, etc.).

[0174] According to some embodiments of the present invention, the device for enhancing electromagnetic radiation and cooling of objects and / or object surfaces via anti-Stokes fluorescence 100, 200, 300, 400 can cool liquids such as water / chemicals / or wax (which, when used as a "cold condenser", solidifies at night and re-liquefies during the day), as well as gases such as water vapor (for the purpose of extracting water from the air) and air (for more efficient cooling in air conditioning).

[0175] According to some embodiments of the present invention, the apparatus for enhancing electromagnetic radiation and cooling of objects and / or object surfaces via anti-Stokes fluorescence 100, 200, 300, 400 may be used in a variety of applications, for example in agriculture where it is essential to keep temperatures low during the growing season, harvesting and storage and during storage.

[0176] According to some embodiments of the present invention, the device for enhancing electromagnetic radiation and cooling of objects and / or object surfaces via anti-Stokes fluorescence 100, 200, 300, 400 may be used in barns / chicken coops, tents / caravans / small boats / automotive field including cars / buses / trucks / trains etc / buildings / barracks / buildings / airports / train stations / data centres / industrial trade etc.

[0177] According to some embodiments of the present invention, the device for enhancing electromagnetic radiation and cooling of objects and / or object surfaces via anti-Stokes fluorescence 100, 200, 300, 400 can be used for extracting water from air, for transporting fruits and vegetables, for preserving fuels and chemicals that do not evaporate, for protective clothing and clothing for athletes / firefighters / rescuemen (soldiers and police officers, etc.), for protection of electronic devices standing outside including screens / cell phones / radars etc., for protection of outdoor analytical equipment that requires that the temperature is not extreme or the changes are not too sudden, for military fields including tanks / ammunition / planes and helicopters on the ground / thermal camouflage etc., and for electronic devices in space and high altitudes.

Claims

1. 1. An apparatus for enhancing a cooling mechanism based on absorption of non-coherent non-monochromatic electromagnetic / solar radiation and anti-Stokes fluorescence, comprising: at least one underlayer, said at least one underlayer comprising a single or multiple layer material configured to emit IR radiation; at least one intermediate layer, the at least one intermediate layer being comprised of a single or multiple layer material configured to respond in anti-Stokes fluorescence upon absorption of electromagnetic radiation; and 13. An apparatus comprising: at least one upper layer, the at least one upper layer being comprised of a single or multiple layer material configured to filter the electromagnetic radiation and either transmit a selected spectral band or transmit multiple selected spectral bands of the electromagnetic radiation transmissible to the at least one intermediate layer and the at least one lower layer, wherein if the at least one upper layer transmits the one selected spectral band, the at least one intermediate layer is configured to be responsive to the one selected spectral band and the at least one lower layer is configured to be responsive to the one selected spectral band, or if the at least one upper layer transmits the multiple selected spectral bands, the at least one intermediate layer is configured to be responsive to a first spectral band of the multiple selected spectral bands and the at least one lower layer is configured to be responsive to a second spectral band of the multiple selected spectral bands, the first spectral band and the second spectral band being the same as or different from each other.

2. 10. The device of claim 1, wherein the at least one top layer is further comprised of a single or multiple layer material configured to enhance one or more selected spectral bands of the electromagnetic radiation transmittable to the at least one intermediate layer.

3. The device of claim 1 , wherein the at least one underlayer is configured to reflect at least 50% of the electromagnetic radiation.

4. The device of claim 1 , further comprising at least one additional layer configured to emit IR radiation.

5. Further comprising at least one insulating layer; 2. The device of claim 1, wherein the insulating layer is selected from an insulating layer that is transparent to electromagnetic radiation, an insulating layer made of very low IR absorbing polymers and materials, an insulating layer that is a membrane made of air, an ITVO (infrared transparent, visible light opaque) material, an insulating layer that is a membrane having a thickness in the range between 1 millimeter and 10 centimeters, the transparency of the membrane to electromagnetic radiation decreasing in proportion to its thickness, an insulating layer that is a membrane made of an electromagnetic radiation selective transparent material selected from porous PTFE, PMMA (polymethyl methacrylate), PS (polystyrene).

6. The device of claim 5 , wherein the insulating layer is a microporous membrane having pores with diameters smaller than 5 μm.

7. The apparatus of claim 5 , wherein the insulating layer is a porous PTFE membrane.

8. The device of claim 1 , wherein the spectral band of the anti-Stokes fluorescence in the at least one intermediate layer is comprised between 300 nm and 1500 nm.

9. 9. The device according to claim 1, wherein the at least one underlayer emits IR radiation in the infrared spectrum in the range of 8 μm to 14 μm.

10. 9. The apparatus of claim 1 further comprising at least one adhesive layer beneath said at least one underlayer for attaching said apparatus to an object to be cooled.

11. 9. The device of claim 1, further comprising at least one upper mechanical layer for protecting the device against mechanical degradation.

12. The device of claim 1 , wherein the at least one lower layer, the at least one middle layer and the at least one upper layer are bonded to one another through an adhesive matrix domain.

13. 9. The device according to claim 1 , wherein the at least one lower layer and / or the at least one upper layer and / or the at least one intermediate layer are provided in one or more membranes.

14. 9. The device of claim 1, wherein the at least one underlayer is composed of a fluorescent material having a QY of at least 90%.

15. 9. The device of claim 1, wherein the at least one intermediate layer is composed of at least one material selected from cadmium sulfide, gallium arsenide (GaAs) quantum wells, ytterbium doped yttrium lithium fluoride (Yb:YLF) crystals, ytterbium doped tungsten crystals (Yb:KGW), fluorozirconate glass doped with 1 wt% Yb3+ (ZBLANP), 9Be+, cesium, CdS / ZnS, perovskites, pyranine, BPEA, rhodamine 101 (xanthine family), and pyrromethene 567 (bodipy family).

16. The device of claim 1 , wherein the at least one intermediate layer is composed of a fluorescent material having a QY of at least 90%.

17. The at least one underlayer may be a continuous or porous PTFE or PTFE nano or microparticle, a continuous or porous PDMS or PDMS nano or microparticle, a continuous or porous SiO ２ Or SiO ２ Nano or particulate, continuous or porous etched ceramic, TiO ２ , BaSO ４ , metal, SiO ２ , Si polymer, HDPE (high density polyethylene), PS (polystyrene), germania, alumina, titania, barium sulfate or nano- or microparticles thereof, wherein said nano- or microparticles are free-standing or embedded in a film, matrix or membrane; the continuous PDMS is provided as a film, wherein the thickness of the continuous PDMS film is between 3.5 μm and 5 μm; The device of claim 1 , wherein the porous PDMS is provided as a membrane.

18. The device of claim 17, wherein the at least one underlayer is a membrane having a thickness in the range of 1 to 1000 μm.

19. The device according to any one of claims 1 to 8, wherein the at least one underlayer is made of a porous material having strong optical activity in the LW-FIR region.

20. The device according to claim 1 , wherein the device is incorporated into a textile fabric.

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