Patent Application
20110013253
The invention relates in general to an integrated film with optical properties, and more particularly to integrated film with optical properties including wavelength shifting.
Various types of films and transparent materials have shown great promise in recent years in applications, for example, such as materials used to manufacture low E (low-emissivity) windows. As energy conservation becomes more important, architects and builders need improved transparent covering materials for windows and walls in building and home construction. Such materials need not only to efficiently deliver illuminating light and solar heating, but also to limit the loss of energy from within temperature controlled spaces. In fact, as material properties improve, there can be building applications where transparent surfaces become entire walls instead of just windows. Similarly, green house plant growing applications often employ transparent walls. One drawback to most existing highly efficient transparent materials is that they can add too much heat to a space, thus requiring wasteful cooling.
In contrast with windows and transparent walls, camouflage has traditionally been accomplished by mostly opaque optical coverings. While it is used primarily in military applications, camouflage can also have aesthetic applications, such as for tailoring the look of buildings or landscapes. However, camouflage in general does nothing with respect to energy efficiency.
Therefore what is needed are materials that can provide more energy-efficient operation, including for such uses as energy conversion, energy management, and for camouflage applications.
In one aspect, the invention relates to an integrated film which includes a plasmonic layer including a pattern configured to support plasmon waves. The plasmonic layer is configured to receive as input light energy of an incident light including at least one photon having a first wavelength and an at least one photon of light received from one or more layers in optical communication with the plasmonic layer and to re-emit as output a guided light to the one or more layers in optical communication with the plasmonic layer. The integrated film also includes a wavelength conversion layer optically coupled to the plasmonic layer. The wavelength conversion layer is configured to receive as input the at least one photon having a first wavelength and to provide as output at least one photon having a second wavelength different than the first wavelength.
In one embodiment, guided light includes a concentrated light.
In another embodiment, the incident light includes a source of electromagnetic waves generated by a selected one of a terrestrial electromagnetic wave or an extraterrestrial electromagnetic wave.
In yet another embodiment, the plasmonic layer includes a film having a thickness of comparable dimension to a skin depth of a photon of the incident light.
In yet another embodiment, the pattern includes a plurality of shapes selected from the group consisting of rods, rectangles, triangles, linear ridges, circular ridges, spiral ridges, and stars.
In yet another embodiment, each of the shapes has a physical dimension of about a wavelength of the incident light.
In yet another embodiment, the pattern has a pattern distribution selected from the group consisting of a periodic pattern distribution, a non-periodic pattern distribution, and a random pattern distribution.
In yet another embodiment, one or more of the shapes includes a protrusion extending outward from a surface of the film.
In yet another embodiment, one or more of the shapes includes a depression extending into a surface of the film.
In yet another embodiment, one or more of the shapes include a void defined in the film and extending from a first surface to a second surface of the film.
In yet another embodiment, one or more of the shapes includes a void surrounded by a plurality of protrusions.
In yet another embodiment, one or more of the shapes includes a void surrounded by a plurality of depressions.
In yet another embodiment, the film includes an electrically conductive film.
In yet another embodiment, the electrically conductive film includes a selected one of a metal and an alloy made from metals selected from the group consisting of gold, silver, chromium, titanium, copper, and aluminum.
In yet another embodiment, the electrically conductive film includes a transparent conductive oxide layer.
In yet another embodiment, the transparent conductive oxide includes a selected one of indium-tin-oxide (ITO) and zinc oxide (ZnO).
In yet another embodiment, the plasmonic layer includes a plurality of patches disposed on a surface, each one of the patches having a thickness of comparable dimension to a skin depth of a photon of the incident light.
In yet another embodiment, each one of the patches has a shape selected from the group consisting of rods, tubes, rectangles, triangles, linear ridges, circular ridges, spirals, spiral ridges, and stars.
In yet another embodiment, each of the shapes has a physical dimension of about a wavelength of the incident light.
In yet another embodiment, the pattern has a pattern distribution selected from the group consisting of a periodic pattern distribution, a non-periodic pattern distribution, and a random pattern distribution.
In yet another embodiment, the surface includes an optically conductive substrate.
In yet another embodiment, the surface includes a surface of a wavelength conversion layer.
In yet another embodiment, each one of the patches includes an electrically conductive material.
In yet another embodiment, the electrically conductive material includes a metal selected from the group consisting of gold, silver, chromium, titanium, copper, and aluminum.
In yet another embodiment, the electrically conductive material includes a transparent conductive oxide layer.
In yet another embodiment, the transparent conductive oxide includes a selected one of indium-tin-oxide (ITO) and zinc oxide (ZnO).
In yet another embodiment, the plasmonic layer is configured such that a received photon causes a selected one of an electric field and a magnetic field to have a higher field strength near each of the patches as compared to a field strength in a void between the patches.
In yet another embodiment, the wavelength conversion layer includes a substantially optically transparent matrix.
In yet another embodiment, the substantially optically transparent matrix includes a material selected from the group consisting of glass, ceramic, and polymer.
In yet another embodiment, the substantially optically transparent matrix includes a substantially transparent adhesive.
In yet another embodiment, the wavelength conversion layer includes a material doped with one or more rare earth ions.
In yet another embodiment, the wavelength conversion layer is doped with a conductive element and the wavelength conversion layer is electrically coupled to at least one adjacent layer.
In yet another embodiment, the wavelength conversion layer is configured to receive as input at least one photon having a first wavelength and to provide as output at least one photon having a second wavelength longer than the first wavelength.
In yet another embodiment, the wavelength conversion layer includes a selected one of a phosphor and a fluorophore.
In yet another embodiment, the wavelength conversion layer includes a material doped with a first rare-earth ion and a second rare earth ion, wherein the first rare-earth ion is configured to absorb at least one photon having the first wavelength and the second rare earth ion is configured to emit at least one photon having the second wavelength longer than the first wavelength.
In yet another embodiment, the wavelength conversion layer includes at least one rare earth ion selected from the group consisting of Pr3+, Eu3+, Ce3+, Tm3+, and Yb3+.
In yet another embodiment, the wavelength conversion layer includes a plurality of quantum dots.
In yet another embodiment, the wavelength conversion layer is configured to receive as input at least one photon having a first wavelength and to provide as output at least one photon having a second wavelength shorter than the first wavelength.
In yet another embodiment, the wavelength conversion layer includes a phosphor.
In yet another embodiment, the wavelength conversion layer includes a material doped with a first rare-earth ion and a second rare earth ion, wherein the first rare-earth ion is configured to absorb at least one photon having the first wavelength and the second rare earth ion is configured to emit at least one photon having the second wavelength shorter than the first wavelength.
In yet another embodiment, the wavelength conversion layer includes at least one rare earth ion including a selected one of Er3+, Yb3+, and Nd3+.
In yet another embodiment, the wavelength conversion layer includes a nonlinear material configured to absorb two photons having a first wavelength and to provide as output at least one photon having a second wavelength that is substantially one half of the first wavelength.
In yet another embodiment, the wavelength conversion layer includes a nonlinear material configured to absorb three photons having a first wavelength and to provide as output at least one photon having a second wavelength that is substantially one third of the first wavelength.
In yet another embodiment, the wavelength conversion layer includes at least one material selected from the group of materials consisting of organic material, inorganic material, optical material, and crystal material.
In yet another embodiment, the wavelength conversion layer includes at least one material selected from the group of materials consisting of β-Barium Borate (BBO), potassium dihydrogen phosphate (KDP), potassium titanyl phosphate (KTP), Lithium Niobate (LiNbO3), polydiacetylenes, poly-3-butoxy-carbonyl-methyl-urethane (poly(3BCMU)), poly-3-butoxy-carbonyl-methyl-urethane (poly(4-BCMU))), and dendritic nonlinear organic glass.
In yet another embodiment, the integrated film includes at least one additional wavelength conversion layer.
In yet another embodiment, the integrated film includes at least one wavelength conversion layer configured to receive as input at least one photon having a first wavelength and to provide as output at least one photon having a second wavelength longer than the first wavelength and at least one wavelength conversion layer configured to receive as input at least one photon having a first wavelength and to provide as output at least one photon having a second wavelength shorter than the first wavelength.
In yet another embodiment, an integrated film is configured as a camouflage film.
In yet another embodiment, the camouflage film is further configured to shift a photon of light radiated from a human body or a building, engine to a photon of light having a wavelength outside of a detection range of a selected one of an IR detector and a human eye.
In yet another embodiment, the camouflage film further includes a plurality of plasmonic layers configured to guide an output light in a pre-determined direction.
In yet another embodiment, the wavelength outside of the detection range is substantially at a wavelength that is absorbed by atmospheric water.
In yet another embodiment, the camouflage film of is configured as an element of an article of clothing.
In yet another embodiment, an article of clothing includes one or more layers of a selected one of a fiber and a cloth, and wherein the wavelength shifting layer is disposed near the plasmonic layer and wherein the wavelength shifting layer remains in optical communication with the plasmonic layer.
In yet another embodiment, the article of clothing includes an inner volume adapted to cover at least part of a human body and an outer surface and the article of clothing and wherein the article of clothing is configured to accept a radiated heat from the inner volume of the clothing and to re-emit via the outer surface to a space outside of the clothing one or more photons having a different wavelength than the radiated heat.
In yet another embodiment, the one or more photons re-emitted via the outer surface to a space outside of the clothing are substantially at a wavelength outside of a detection range of a selected one of an IR detector and a human eye.
In yet another embodiment, the article of clothing is configured to redirect a portion of the radiated heat from the inner volume of the clothing back into the inner volume as adapted to minimize a heat loss from a body.
In yet another embodiment, the article of clothing is configured to direct substantially all of the radiated heat from the inner volume of the clothing to the outer surface as adapted to maximize a heat loss from a body.
In yet another embodiment, a camouflage film is configured as an element of an article of camouflage cover.
In yet another embodiment, the element of an article of camouflage cover includes one or more layers of a selected one of a fiber, a cloth and a physically strong supporting film, and wherein the wavelength shifting layer is disposed near the plasmonic layer and wherein the wavelength shifting layer remains in optical communication with the plasmonic layer.
In yet another embodiment, the article of camouflage cover includes an inner volume adapted to cover at least part of an object selected from the group consisting of a machine, an engine, a tent, a building, a vehicle, a tank, an aircraft, a boat, and a ship, and an outer surface and the article of camouflage cover and wherein the article of camouflage cover is configured to accept a radiated heat from the inner volume of the camouflage cover and to re-emit via the outer surface to a space outside of the camouflage cover one or more photons having a different wavelength than the radiated heat.
In yet another embodiment, the one or more photons re-emitted via the outer surface to a space outside of the camouflage cover are substantially at a wavelength outside of a detection range of a selected one of an IR detector and a human eye.
In yet another embodiment, the article of camouflage cover is configured to redirect a portion of the radiated heat from the inner volume of the camouflage cover back into the inner volume as adapted to minimize a rate of heat loss of the object.
In yet another embodiment, the article of camouflage cover is configured to direct substantially all of the radiated heat from the inner volume of the camouflage cover to the outer surface as adapted to maximize a heat loss from the object.
In yet another embodiment, the article of camouflage cover is configured to shift substantially all of the radiated heat from the inner volume of the camouflage cover to a wavelength outside of a detection range of a selected one of an IR detector and a human eye and direct the second wavelength to the outer surface as adapted to maximize a heat loss from the object.
In yet another embodiment, the article of camouflage cover includes one or more plasmonic layers, at least one of the plasmonic layers configured to be removed from the article of camouflage cover.
In yet another embodiment, the at least one of the plasmonic layers are configured to be removed is removed by a mechanical means.
In yet another embodiment, the mechanical means includes an electric motor.
In yet another embodiment, the at least one of the plasmonic layers is configured to be removed is removed by a mechanical means as controlled by a thermostatic control.
In yet another embodiment, the integrated film is configured as a receiving element for a night vision apparatus, wherein the receiving element is configured to shift an incident light to a wavelength that is detectable by a selected one of an IR detector and a human eye.
In yet another embodiment, the receiving element further includes one or more optical lenses.
In yet another embodiment, the one or more optical lenses are configured to correct for a selected one of near-sighted vision and far-sighted vision.
In yet another embodiment, the one or more optical lenses are configured to improve a selected one of intensity of incident light and clarity of incident light.
In yet another embodiment, the plasmonic layer is configured to guide a light of the second wavelength to a selected one of a human eye and an optical surface of a goggle apparatus viewed by a human eye.
In yet another embodiment, an integrated film is configured as a greenhouse cover to convert the incident light to a wavelength conducive to the growth of one or more types of plants.
In yet another embodiment, the greenhouse cover further includes a plurality of plasmonic layers configured to guide an output light in a pre-determined direction.
In yet another embodiment, the second wavelength is configured to be substantially at an optimal wavelength for photosynthesis.
In yet another embodiment, the second wavelength is configured to be substantially at an optimal wavelength for heating a greenhouse.
In yet another embodiment, the greenhouse cover further includes one or more additional layers of a transparent substrate.
In yet another embodiment, the transparent substrate includes a plastic.
In yet another embodiment, an integrated film is configured as a low-emissive film to suppress radiative heat emission.
In yet another embodiment, the low-emissive film is configured to transmit a visible component of the incident light and to convert an infrared wavelength of the incident light to a substantially visible wavelength.
In yet another embodiment, the low-emissive film further includes one or more layers of a transparent substrate.
In yet another embodiment, the one or more layers of a transparent substrate include glass.
In another aspect, the invention relates to an integrated film which includes a wavelength conversion layer, the wavelength conversion layer configured to receive as input at least one photon having a first wavelength and to provide as output at least one photon having the second wavelength different than the first wavelength. The integrated film also includes a plasmonic layer in optical communication with the wavelength conversion layer including a pattern configured to support plasmon waves. The plasmonic layer is configured to receive as input light energy of the emitted light and to re-emit as output a guided light (we can let go the highlighted section if you find it difficult to include), to one or more layers in optical communication with the plasmonic layer. The integrated film also includes a reflector layer in optical communication with the plasmonic layer and configured to reflect at least one photon of the incident light and at least one photon having the second wavelength towards the plasmonic layer.
In one embodiment, the guided light includes a concentrated light.
In another embodiment, the integrated film further includes at least one additional plasmonic layer disposed between any two layers of the integrated film.
In yet another embodiment, the integrated film includes at least one wavelength conversion layer configured to receive as input at least one photon having a first wavelength and to provide as output at least one photon having a second wavelength longer than the first wavelength and at least one wavelength conversion layer configured to receive as input at least one photon having a first wavelength and to provide as output at least one photon having a second wavelength shorted than the first wavelength
The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent from the following description and from the claims.
The objects and features of the invention can be better understood with reference to the drawings described below, and the claims. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the drawings, like numerals are used to indicate like parts throughout the various views.
The detailed description is divided into three parts. In Part I some relevant terms and phrases are defined. In Part II, various embodiments of an integrated solar cell with wavelength shifting are described. Part III describes integrated films with wavelength shifting, such as those useful in camouflage applications.
Wavelength shifting materials: Wavelength shifting materials, also called wavelength conversion materials (materials of wavelength conversion layers) include materials that can absorb in one wavelength and emit in another wavelength. Wavelength shifting materials can be up-converting in wavelength (upconversion, up shifting) or down-converting in wavelength (downconversion, down shifting) materials. Such materials can include linear and nonlinear materials. A downconversion material absorbs at least one photon and emits one or more photons having wavelength longer than the absorbed photon. Examples of downconversion materials include, but are not limited to, phosphors, fluorophors, and semi-conducting materials such as quantum dots. Other examples of downconversion materials include materials doped with one type of rare earth ions. Another example of a downconversion material is a material that is doped with at least two different types of rare earth ions, where at least one ion from a first type of rare earth ion absorbs an incident photon, and transfers the energy to two or more rare earth ions from a second type to emit two or more photon of longer wavelength. Examples of the rare earth ions are, but are not limited to, Pr3+, Eu3+, Ce3+, Tm3+, or Yb3+. An upconversion material absorbs at least one photon and emits at least one photon having wavelength shorter than the absorbed photon. Upconversion materials include, but are not limited to, phosphors. Other examples of upconversion materials include materials doped with one or more types of rare earth ions such as Er3+, Yb3+ or Nd3+. Both up and down conversion materials can also be directly deposited on the surface of an adjacent layer, or be physically dispersed in a transparent matrix such as an adhesive and attached to an adjacent layer. Some wavelength conversion materials are of crystal form and can be formed in a transparent matrix such as glass, ceramic or polymer.
Plasmonic structures: Plasmonic structures are structures that can support propagating or standing collective electron oscillation, also called plasmon waves. Materials for such structures include, but are not limited to, metallic or conductive materials. Examples of suitable materials include, but are not limited to, gold (Au), silver (Ag), copper (Cu), aluminum (Al), indium tin oxide (ITO), zinc oxide (ZnO), silicon or chromium (Cr). Plasmonic structures can also exhibit some properties of a photonic structure such as band gap and light guiding.
Plasmons: plasmons are collective oscillations of the free electrons in a metal or conductive material. Plasmonic structures can be used to generate an enhanced electric field and/or magnetic field by generating resonance between an incident electromagnetic wave and plasmon waves in the structure. In some embodiments, when coupling wavelength shifting materials, such as nonlinear wavelength shifting materials with such structures, wavelength-shifting efficiency can be improved due to enhanced electric or magnetic field. As is well known, an electric field and a magnetic field are two components of an electromagnetic field. Plasmonic structures can also be used to enhance an electric field, a magnetic field or both an electric field and a magnetic field. Plasmonic structures can also be used to absorb certain range of wavelengths efficiently and redirect the light to an adjacent layer.
Geometry of Patterns (including distributions of shapes): Geometry of Patterns and distributions of shapes refer to the geometry of a periodic or non-periodic pattern of a plasmonic structure, also called a plasmonic layer. The geometry of the pattern can be symmetric which can minimize various effects induced by various degrees of polarization, coherency and angle of incident sunlight. Examples of such symmetry include, but are not limited to, spherical, hexagonal, square, triangular, etc. Such structures can also be made non-symmetric to achieve an enhanced electric and/or magnetic field. The geometry of arrays can also determine an optimum range of wavelengths of incident light that can be resonant with the plasmon waves in a plasmonic structure and induce enhanced electric and/or magnetic fields, or the efficiency of absorption and redirection of an incident light.
Quantum Dots: Quantum dots can include a variety of geometries including, for example, quantum dots which are spherical in shape, quantum spikes, quantum stars, etc. Quantum dots are nanocrystals or microcrystals that contain a droplet of electrons (due to the confined size of the quantum particle). The nanocrystals or microcrystals are typically semiconductor nanocrystals or microcrystals. Made of semiconducting materials, quantum dots can absorb a wide range of wavelengths of light and re-emit the light in a narrow range of wavelength of light. As described in more detail below, quantum dots can be used in solar applications, such as solar cell applications, including wavelength conversion. In some embodiments, quantum dots can be used to broaden the absorption bandwidths of some wavelength shifting materials such as, for example, rare earth ion doped materials. Quantum dots can either replace the absorbing element of a wavelength conversion material to absorb a wide range of light and transfer the energy to the emitting element of a wavelength conversion material, or can be added into a wavelength conversion material to absorb a wide range of light and transfer the energy to the absorbing element of a wavelength conversion material.
Part II, Integrated Solar Cells with Wavelength Shifting:
Integrated solar cells can be used to convert an incident light falling within a terrestrial solar spectrum. Such applications typically include green power solar generation applications. Integrated solar cells can also be particularly useful in other applications, for example in applications where the incident light has little energy that can be directly converted by one or more photovoltaic layers. In such applications, most of the photons which are converted to electricity are those which are wavelength shifted by a wavelength conversion layer 101. Also, as described above, since wavelength conversion layers 101 typically emit wavelength converted light in an isotropic radiation pattern, one or more plasmonic layers 102 can redirect wavelength converted light that would not otherwise reach one or more photovoltaic layers 103, thus enhancing the efficiency of the integrated solar cell.
Plasmonic Layer: As described above, a plasmonic layer includes a pattern designed to support plasmon waves. The plasmonic layer can be fabricated either as a film with physical features or as a collection of patches or “islands” formed on a surface. In general, a plasmonic layer accepts light as input and there can be a resonance between the input light and plasmon waves caused by the pattern of the plasmonic layer. The plasmonic layer can then output a directed or concentrated light.
Embodiments of integrated solar cells having a plasmonic layer fabricated as a film having physical features are now described in more detail. A film with physical features has a thickness of comparable dimension to a skin depth of a photon of light (e.g. a wavelength range of the terrestrial solar spectrum). The pattern of the plasmonic layer can include a plurality of shapes such as, rods, rectangles, triangles, linear ridges, circular ridges, spiral ridges, and stars. Each one of the shapes can also have a physical dimension of about a wavelength of light, such as in a wavelength range of the terrestrial solar spectrum. The pattern of a plasmonic layer can have a variety of pattern distributions. For example, the pattern distribution can be a periodic pattern distribution, a non-periodic pattern distribution, and a random pattern distribution. The physical features in a plasmonic film structure can be protrusions extending outward from a surface of the film, depressions extending into a surface of the film, or voids extending through both surfaces of the film. The physical features can also include any combination of two or more types of protrusions, depressions, or voids. For example, a pattern can be formed from a shape having a void surrounded by one or more protrusions. Or, a pattern can be formed from a shape having a void surrounded by a plurality of depressions. On receiving a photon, a plasmonic layer formed from a distribution of voids, protrusions and/or depressions can cause there to be a higher electric and/or magnetic field strength near some voids (spaces), protrusions or depressions as compared to the field strength in film areas between the voids, protrusions or depressions.
In some embodiments, the film can be an electrically conductive film. An electrically conductive film can be a metal film made from gold, silver, chromium, titanium, copper, and aluminum or some combination thereof. An electrically conductive film can also be fabricated as a transparent conductive oxide layer. A transparent conductive oxide layer can be made from indium-tin-oxide (ITO) or zinc oxide (ZnO) materials.
Embodiments having a plasmonic layer fabricated as a collection of patches or “islands” formed on a surface are now described in more detail. A plasmonic layer can be created by a plurality of patches formed or deposited on a surface. Each of the patches typically has a thickness of comparable dimension to a skin depth of a photon of light (e.g. a wavelength range of the terrestrial solar spectrum). Patches can have shapes such as rods, tubes, rectangles, triangles, linear ridges, circular ridges, spirals, spiral ridges, and stars. Each of the shapes typically has a physical dimension of about a wavelength of light, such as in a wavelength range of the terrestrial solar spectrum. Suitable pattern distributions include periodic pattern distributions, non-periodic pattern distributions, and random pattern distributions. On receiving a photon, a plasmonic layer formed from a distribution of patches can cause there to be a higher electric and/or magnetic field strength near some patches as compared to the field strength in voids (spaces) between the patches.
Patches are typically formed or distributed on a surface. In some embodiments an optically conductive substrate can provide a suitable surface. In other embodiments, patches can be formed or deposited directly on a surface of another layer, such as a wavelength conversion layer or a photovoltaic layer. Patches can be fabricated using an electrically conductive material. For example, patches can be fabricated from a metal such as gold, silver, chromium, titanium, copper, and aluminum. Or, in other embodiments, patches can be made from a transparent conductive oxide material. Suitable conductive oxides include indium-tin-oxide (ITO) or zinc oxide (ZnO).
Several examples of shapes useful for plasmonic film or patch layers are now described.
In general, light absorbing, concentrating, shifting, reemitting and guiding structures for solar energy to electrical energy conversion as described above can also include a photon conversion material (e.g. a wavelength conversion layer) to convert the incident electromagnetic waves to desired frequencies. The optical conversion materials, also referred to as wavelength conversion materials herein, can shift electromagnetic waves to higher or lower frequencies, depending on choice of the photon conversion material. Examples of suitable wavelength conversion materials include, but are not limited to, organic nonlinear optical materials (NLOs), organic and inorganic nonlinear crystals, rare earth ion doped photon-conversion materials, and luminescent quantum dots and fluorophores. Examples of these materials include, polydiacetylenes (include poly-3-butoxy-carbonyl-methyl-urethane (poly(3BCMU)) and poly-3-butoxy-carbonyl-methyl-urethane (poly(4-BCMU))), β-Barium Borate (β-BaB2O4 or BBO), potassium dihydrogen phosphate (KDP), potassium titanyl phosphate (KTP), lithium niobate, dendritic nonlinear organic glasses, and rare earth ions doped photon-conversion materials such as Erbium (Er3+), Ytterbium (Yb3+), Neodymium (Nd3+) doped polymer or glasses.
Structures to enhance plasmonic effects can include 2D periodic or non-periodic structures, and 3D periodic or non-periodic structures that can be used to enhance plasmonic effects, i.e., to enhance the electric and/or magnetic fields, concentrating and guiding light. As described in more detail below, such structures can be used in solar applications, such as solar cell applications, to guide light, and/or to improve the efficiency of wavelength conversion materials to solar efficiency. For example, plasmonic structures can be used to generate enhanced electric and/or magnetic fields, and/or to control the emission environment of wavelength shifting materials to enhance radiative rates, and therefore to increase wavelength-shifting efficiency. Typically when a wavelength shifting material absorbs a photon, two processes occur: radiative decay (i.e., spontaneous emission, light emission) and non-radiative decay (i.e., heat). In up-shifting wavelength conversion materials, the wavelength conversion process is generally nonlinear. Enhancing electric and/or magnetic field can quadruply increase the intensity of radiative decay, and therefore the wavelength conversion efficiency. For all wavelength conversion materials, both up-shifting and down-shifting, linear and nonlinear, plasmonic structures can be used to form an environment that facilitates the radiative decay, therefore a speeding up radiative decay cycle, thus enhancing the radiative decay and therefore increasing the efficiency of a solar cell. In addition to enhancing the rate of radiation, plasmonic structures can also direct the emission light. Such structures can be included in solar application to guide incident, shifted, and re-emitted light to solar cell for improved solar cell efficiency. Multiple types of structures can be used, for example, a first structure for enhancing electric/magnetic field for enhanced wavelength conversion, and a second structure for enhancing radiative decay rate for enhanced wavelength conversion, and a third structure for guiding the light to a solar cell. Alternatively, a plasmonic structure can have multiple above said functions.
Photovoltaic Layer: As described above, a photovoltaic layer is optically coupled to other layers of the integrated solar cell structure. One or more photons of the incident light can be directly converted by photovoltaic layer to electrical energy. Or, in cases where most or all of the energy of the incident light is not within a bandwidth suitable for direct conversion by photovoltaic layer, a photovoltaic layer can convert photons of a second wavelength (a converted wavelength) to electricity, or a photovoltaic layer can convert both incident light (un-converted wavelengths) and light of a second (converted) wavelength to electricity.
The photovoltaic layer can be fabricated from any suitable photovoltaic material, such as an amorphous silicon photovoltaic material, a micro-crystalline silicon photovoltaic material, a nano-crystalline silicon photovoltaic material, a crystalline silicon photovoltaic material, a cadmium telluride (CdTe) photovoltaic material, a copper indium germanium selenium (CIGS), or an organic photovoltaic material.
Optically Transparent Conductive Layer: Substantially optically transparent electrically conductive layers can be disposed between any of the layers of an integrated solar cell to improve electrical contact between the layers. For example, a substantially optically transparent electrically conductive layer can be disposed between a plasmonic layer and a wavelength conversion layer to improve electrical contact between the plasmonic layer and the wavelength conversion layer. Or, a substantially optically transparent electrically conductive layer can be disposed between a wavelength conversion layer and a photovoltaic layer to improve electrical contact between the wavelength conversion layer and the photovoltaic layer.
Example of an Integrated Solar cell with two plasmonic layers:
Wavelength Conversion Layer: As described above, a wavelength conversion layer (wavelength shifting) can be optically coupled to other layers of integrated solar cell including one or more plasmonic layers and one or more photovoltaic layers. A wavelength conversion layer typically receives as input at least one photon having a first wavelength and provides as output at least one photon having a second wavelength different than the first wavelength. A down shifting wavelength conversion layer converts at least one photon having a first wavelength to at least one photon having a second wavelength longer than the first wavelength. An up shifting wavelength conversion layer converts at least one photon having a first wavelength to at least one photon having a second wavelength shorter than the first wavelength.
Down shifting wavelength conversion layers are now described in more detail. A down shifting wavelength conversion layer can include a phosphor, a fluorophore, or a quantum dot material, and can be doped with one or more rare earth ions. A down shifting wavelength conversion layer can include a material doped with a first rare-earth ion and a second rare earth ion, wherein the first rare-earth absorbs at least one photon having the first wavelength and the second rare earth ion emits at least one photon having the second wavelength longer than the first wavelength. Exemplary rare earth ions suitable for use in a down shifting wavelength conversion layer include Pr3+, Eu3+, Ce3+, Tm3+, and Yb3+
The wavelength conversion layer can include a substantially optically transparent matrix. The substantially optically transparent matrix can be, for example, a glass matrix, a ceramic matrix, or a polymer matrix. Some wavelength conversion materials are of crystal form and may be formed by cooling of a molten state of the mixture of the components of wavelength conversion materials and glass or ceramic matrix. Resulting is a wavelength conversion layer with wavelength material crystallized in a transparent matrix. A wavelength conversion layer can also be formed by dispersing wavelength conversion materials in a transparent matrix such as a polymer during the formation of the matrix. Or, when a wavelength conversion layer is fabricated using a substantially transparent adhesive, the matrix solidifies to “fix” a distribution of materials. A wavelength conversion layer can also include a plurality of quantum dots. In some embodiments, a wavelength conversion layer can also be doped with a conductive element and so that the wavelength conversion layer is electrically coupled to an adjacent layer.
Up shifting wavelength conversion layers are now described in more detail. An up shifting wavelength conversion layer can include a material doped with a first rare-earth ion and a second rare earth ion. The first rare-earth ion is configured to absorb at least one photon having a first wavelength and the second rare earth ion is configured to emit at least one photon having a second wavelength shorter than the first wavelength. An up shifting wavelength conversion layer can include at least one rare earth ion such as Er3+, Yb3+, and Nd3+. An up shifting wavelength conversion layer can also include a substantially optically transparent matrix. The substantially optically transparent matrix can include a material such as glass, ceramic, or polymer. Or, the substantially optically transparent matrix can be made from a substantially transparent adhesive.
A nonlinear material of an up shifting wavelength conversion layer can absorb two photons having a first wavelength and output at least one photon having a second wavelength that is substantially one half of the first wavelength. Similarly, a nonlinear material can absorb three photons having a first wavelength and provide as output light at least one photon having a second wavelength that is substantially one third of the first wavelength.
Exemplary materials suitable for forming a wavelength conversion layer include organic material, inorganic material, optical material, and crystal material. A wavelength conversion layer can also include materials such as β-Barium Borate (BBO), potassium dihydrogen phosphate (KDP), potassium titanyl phosphate (KTP), and Lithium Niobate (LiNbO3). A wavelength conversion layer can also be doped with a conductive element so that the wavelength conversion layer is electrically coupled to an adjacent layer.
Also, note that with regard to both down shifting and up shifting wavelength conversion layers, an integrated solar cell can have two or more wavelength conversion layers. For example, there can be one or more down shifting wavelength conversion layers in addition to one or more up shifting wavelength conversion layers. Or, in other embodiments there can be one or more down shifting wavelength conversion layers having different wavelength bandwidths.
Also, a wavelength conversion layer can include one or more semiconducting materials. The one or more semiconducting materials can cause a broadening in a bandwidth of the absorption wavelength of the wavelength conversion layer.
Examples, Integrated solar cell with Reflector Mirror:
As in earlier embodiments described above, an integrated solar cell with wavelength conversion and a reflector layer 2000 can also include one or more substantially optically transparent electrically conductive layers disposed between any two layers of the integrated solar cell. The substantially optically transparent electrically conductive layers can improve an electrical contact between any two layers of the integrated solar cell.
Part III, Integrated Films with Wavelength Shifting
An integrated film can include any of the plasmonic layers and any of the wavelength shifting layers described hereinabove in part II. Integrated films, however, generally do not include a photovoltaic layer.
The plasmonic layer 102 of an integrated film can include any of the features, properties, and/or materials described above in part II. Similarly the wavelength conversion layer 101 of an integrated film can include any of the features, properties, and/or materials described above in part II. Also, an integrated film can have one or more plasmonic layers 102 and/or one or more wavelength conversion layers 101. An integrated film can also include an additional reflector layer 2000 as described above in part II.
Camouflage Films: An integrated film with wavelength shifting as described above can be used as a camouflage film to make various types of camouflage apparatus. The phrases used herein to describe various embodiments of camouflage apparatus, such as and including, camouflage film, camouflage clothing, and camouflage fabric are used interchangeably for military and civilian applications as well as interchangeably for applications for camouflage (minimizing visual detection) and/or applications for controlling the temperature of a body or inanimate object in a volume covered by or otherwise contained within or behind a camouflage apparatus based on an integrated film (including, for example, applications where only temperature control is desired).
For example, a camouflage film can be configured to shift a photon of light radiated from a human body or a building, engine to a photon of light having a wavelength outside of a detection range of a selected one of an IR detector and a human eye. As is well know, all bodies, including human, animal, and inanimate bodies, radiate heat, typically including radiated heat over a wide range of IR wavelengths. A camouflage apparatus, such including camouflage fabrics, camouflage clothing, and other types of camouflage films, can convert IR radiation received on a first side of the camouflage apparatus to a second wavelength that is emitted from the second side out into a space past the second side. The camouflage apparatus can be configured such that one or more photons emitted from the second side at the second wavelength fall in a range of wavelength substantially not visible to an electronic IR detector or to the human eye. In other embodiments, a camouflage film can emit light substantially at a wavelength that is absorbed by atmospheric water, thus creating a range at which an object behind or within such a camouflage apparatus can be masked by the atmospheric water absorption. Also, a camouflage film can include a plurality of plasmonic layers configured to guide an output light in a pre-determined direction.
Camouflage films can also be used as an element of an article of clothing. For example, an article of clothing can include one or more layers of a fiber or cloth. A wavelength shifting layer can be disposed near a plasmonic layer so that the wavelength shifting layer still remains in optical communication with the plasmonic layer. An article of clothing can include any typical article of clothing such as a jump suit, soldier's uniform or fatigues, pants, trousers, shirts, jackets, hats, gloves, socks, coats, etc. An article of clothing typically has an inner volume adapted to cover at least part of a human body and an outer surface. The article of clothing can be configured to accept a radiated heat from the inner volume of the clothing and to re-emit via the outer surface to a space outside of the clothing one or more photons having a different wavelength than the radiated heat. Thus, such an article of clothing can function as a camouflage apparatus as described above. For example, the article of clothing can be configured where one or more photons that are re-emitted via an outer surface to a space outside of the clothing are substantially at a wavelength outside of a detection range of an IR detector or a human eye.
Another use of such articles of clothing is to help control or regulate the temperature of a body wearing clothing based on an integrated film with wavelength shifting. For example in cooler or cold weather, the article of clothing can be configured to redirect a portion of heat radiated from a body within an inner volume of the clothing back into the inner volume to help minimize heat loss from a body, e.g. to keep a person wearing the clothing warm. Or, in other embodiments, in warmer or hot weather, the article of clothing can be configured to direct substantially all of the radiated heat from the inner volume of the clothing to an outer surface to maximize heat loss from the body, such as to keep a person wearing the clothing cool.
Another use of such articles of clothing is to camouflage as well as to help control or to regulate the temperature of a body wearing clothing based on an integrated film with wavelength shifting. In such an arrangement, one or more plasmonic layers are used to guide the heat radiated directly from a body and/or the shifted radiation emitted from wavelength conversion layer. For example in cooler or cold weather, the article of clothing can be configured to redirect all or a portion of heat radiated from a body within an inner volume of the clothing and the shifted radiation back into the inner volume to help minimize heat loss from a body, e.g. to keep a person wearing the clothing warm. Or, in other embodiments, in warmer or hot weather, the article of clothing can be configured to direct substantially all of the radiated heat from the inner volume of the clothing to wavelength conversion layer for shifting and then direct the shifted radiation to an outer surface to maximize heat loss from the body, such as to keep a person wearing the clothing cool.
In other embodiments, a camouflage film can be configured as an element of an article of camouflage cover. An article of camouflage cover can include one or more layers of a fiber, cloth, or metal. A wavelength shifting layer can be disposed near a plasmonic layer such that the wavelength shifting layer remains in optical communication with the plasmonic layer. The article of camouflage cover can include an inner volume adapted to cover at least part of an object. Objects can include virtually any physical object that can be covered, such as, for example a machine, an engine, a tank, a tent, a building, a vehicle, an aircraft, a boat, and a ship. A camouflage cover can be configured to accept a radiated heat from an inner volume (e.g. a volume under, behind, or otherwise covered by a camouflage cover). The camouflage cover re-emit via an outer surface to a space outside of the camouflage cover one or more photons having a different wavelength than a heat radiated from within or behind the camouflage cover. The camouflage cover can be configured such that one or more photons are re-emitted via the outer surface to a space outside of the camouflage cover at substantially a wavelength outside of a detection range of an IR detector or a human eye.
In temperature control applications, a camouflage cover can also be configured to redirect a portion of radiated heat from the inner volume of the camouflage cover back into an inner volume to minimize a rate of heat loss of the object. Or, in other embodiments, a camouflage cover can also be configured to direct substantially all of the radiated heat from an inner volume of the camouflage cover to an outer surface to maximize a heat loss from the object. Also in temperature control applications, a camouflage cover can be more made configurable where at least one plasmonic layer is configured to be removed from an article of camouflage cover. For example, a plasmonic layer can be configured to be removed by a mechanical means, such as an electric motor. In still more sophisticated temperature control applications, the movement of a mechanically configurable plasmonic layer can be controlled by a thermostat.
In camouflage and temperature control applications, a camouflage cover can also be configured to redirect a portion of radiated heat from the inner volume of the camouflage cover as well as shifted radiation back into an inner volume to minimize a rate of heat loss of the object. Or, in other embodiments, a camouflage cover can also be configured to direct substantially all of the radiated heat from an inner volume of the camouflage cover to a wavelength conversion layer and then to direct the shifted radiation to an outer surface to maximize a heat loss from the object. Also in temperature control applications, a camouflage cover can be more made configurable where at least one plasmonic layer is configured to be removed from an article of camouflage cover. For example, a plasmonic layer can be configured to be removed by a mechanical means, such as an electric motor. In still more sophisticated temperature control applications, the movement of a mechanically configurable plasmonic layer can be controlled by a thermostat.
Another embodiment of a camouflage cover can include multiple plasmonic layers where one or more layers can be removed or re-added to change the direction of the radiation, such as both an incident or re-emitted radiation. The addition or removal of one or more layers can be achieved by any suitable mechanical or electrical means, such as was described above. For example, in some embodiments, a mechanical spring can be embedded in a removable plasmonic layer as a backbone. Forces can be applied, for example, on both sides of the spring to keep the plasmonic layer present in the path of radiation. Then, as desired, forces that keep the spring open can be removed to retract or fold the layer to remove it from the path of the light. In still other embodiments, a foldable rod attached to a removable plasmonic layer as a backbone can be connected to an electrical motor. When desired, the motor can operate to roll or fold the plasmonic layer and remove it from the path of radiation. Also, in any of the above embodiments, one or more temperature sensors can be built into the integrated film.
Regarding the above camouflage and thermal applications, typically, heat generated by a warm body (human or engines) covers a large range of wavelengths from ˜2 micron to ˜20 micron. Most IR detectors can only see radiation at a mid-range IR (3-5 um) or a long-wavelength IR (8-12 um). Water absorbance is generally at about 6-7 um. Therefore, for a camouflage device, the integrated film can shift all or most heat from a warm body to the ranges that fall into gaps of the various commonly used IR detectors and/or into to the water absorbance band. Note that in some embodiments, the shifted wavelength is still within IR range (heat).
Night Vision Apparatus: An integrated film can be configured as a receiving element for a night vision apparatus. The receiving element can be configured to shift an incident light to a wavelength that is detectable by an IR detector or a human eye. Such receiving element can include one or more optical lenses. The one or more optical lenses can be configured to correct for the near-sighted or far-sighted vision of a human observer. The one or more optical lenses can also be configured to improve the intensity of an incident light and/or to clarity an object viewable via an incident light. A plasmonic layer can be configured to guide a light of a second wavelength to either a human eye or to an optical surface, such as a face of goggle.
Greenhouse Applications: An integrated film can also be configured as a greenhouse cover to convert an incident light (typically a solar incident light) to a wavelength conducive to the growth of one or more types of plants. A greenhouse cover can also include a plurality of plasmonic layers configured to guide an output light in a pre-determined direction. A greenhouse cover can provide a second wavelength that is configured to be substantially at an optimal wavelength for photosynthesis. Or, in other embodiments, the second wavelength can e configured to be substantially at an optimal wavelength for heating the greenhouse. Such covers can also include multiple wavelength layers to provide light at both wavelengths conducive to plant growth and to greenhouse heating. A greenhouse cover can also include one or more additional layers of a transparent substrate. A transparent substrate can be made from a plastic.
Low E (low-emissive films): An integrated film can be configured as a low-emissive film to suppress radiative heat emission. A low-emissive film can be configured to both to transmit a visible component of incident light and to convert an infrared wavelength of the incident light to a substantially visible wavelength. A low-emissive film can include one or more layers of a transparent substrate. The one or more layers of a transparent substrate can be made from glass.
This application claims priority to and the benefit of co-pending U.S. provisional patent application Ser. No. 61/035,510, entitled THIN FILM ELEMENT FOR ABSORBING, SHIFTING AND REEMITTING ELECTROMAGNETIC WAVES, filed Mar. 11, 2008, co-pending U.S. provisional patent application Ser. No. 61/116,743, entitled TWO-DIMENSIONAL PHOTONIC CRYSTAL STRUCTURES, filed Nov. 21, 2008, co-pending U.S. provisional patent application Ser. No. 61/116,755, entitled PERIODIC OR NON-PERIODIC NANOSTRUCTURES TO CONTROL EMISSION ENVIRONMENT FOR ENHANCED WAVELENGTH SHIFTING EFFICIENCY filed Nov. 21, 2008, co-pending U.S. provisional patent application Ser. No. 61/147,937, filed Jan. 28, 2009, entitled IMPROVING EFFICIENCIES OF PV CELLS USING PLASMONIC AND PHOTOVOLTAIC NANOARRAYS, which applications are incorporated herein by reference in their entirety. This application is also related to co-pending PCT Application No. _______ , entitled INTEGRATED SOLAR CELL WITH WAVELENGTH CONVERSION LAYERS AND LIGHT GUIDING AND CONCENTRATING LAYERS, filed Mar. 11, 2009, which is incorporated by reference in its entirety.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US09/36817 | 3/11/2009 | WO | 00 | 9/7/2010 |
| Number | Date | Country | |
|---|---|---|---|
| 61035510 | Mar 2008 | US | |
| 61116743 | Nov 2008 | US | |
| 61116755 | Nov 2008 | US | |
| 61147937 | Jan 2009 | US |
