Windows with quantum dot-containing sealants

Abstract

1. An article comprising: (a) a window pane having opposing major surfaces and an edge extending around the major surfaces; (b) a window frame around at least a portion of the edge of the window pane; and (c) a sealant in optically transmissive contact with the edge of the window pane, wherein the sealant comprises quantum dots.

Description

[Technical Field]

[0001] The present invention relates to window articles that include a sealant containing quantum dots. [Background technology]

[0002] Introduction Solar energy is one source of sustainable "clean" energy that continues to grow in interest and applications. Collecting solar energy typically requires placing solar cells that convert light into electrical energy in a way that allows sunlight to shine on the solar cells. Placing solar cells on the roof or outdoors of a building is a common practice for collecting solar energy to optimize the solar cells' exposure to sunlight.

[0003] Collecting solar energy is more difficult when there are obstacles to sunlight exposure. For example, buildings in urban environments, such as large cities, typically have other buildings that block sunlight exposure. Similarly, forested areas have trees that block sunlight exposure, making sunlight harvesting difficult for homes and buildings in forested areas. A method of concentrating sunlight reaching a building would aid in efforts to collect solar energy, particularly in environments such as urban and forested areas. Even better would be a way to direct that concentrated sunlight toward a solar cell. Furthermore, it would be even more desirable if such a means could direct and concentrate toward the solar cell the wavelengths of sunlight that the solar cell most efficiently converts into electrical energy.

[0004] Luminescent solar concentrators are one technology that has been developed for such applications. For example, see Moraitis et al., Opt. Mater. 2018, 84, 636-645 for a review of this technology. However, there is still room for improvement in luminescent solar concentrator technology for window applications. Summary of the Invention

[0005] The present invention provides a solution to the problem of providing an improvement over luminescent solar concentrator technology when applied to window applications.

[0006] The present invention is the result of the discovery that quantum dots can be present in a sealant for a window article. The quantum dots in the sealant for a window article absorb light and convert it to wavelengths usable by solar cells, allowing the light to be converted into electrical energy. Advantageously, the quantum dots in the window sealant are not present on the viewing surface of the window, and as a result, do not affect the field of view through the window. One drawback of incorporating quantum dots into a window is that they tend to affect visibility through the window. By placing the quantum dots in a sealant around the window glass, the quantum dots are placed outside the viewing surface of the window, thereby avoiding any impact on the field of view through the window. Nevertheless, the quantum dots in the sealant can still absorb that light and convert it into electrical energy. Particularly advantageous is the fact that the quantum dots in the sealant can convert light that would otherwise be lost by escaping the window glass through the edge of the window glass. Furthermore, the quantum dots in the window sealant can be used in combination with quantum dots elsewhere in the window structure, including the viewing surface, to increase the amount of light entering the window that can be converted into electrical energy.

[0007] In a first aspect, the invention is an article that includes: (a) a pane having opposing major surfaces and an edge extending around the major surfaces; (b) a pane around at least a portion of the edge of the pane; and (c) a sealant in optically transmissive contact with the edge of the pane, wherein the sealant includes quantum dots.

[0008] The articles of the present invention are useful as windows in structures that convert incident light into electrical energy. [Brief explanation of the drawings]

[0009] [Figure 1(a)] 1 shows a front view of the article of the present invention, looking into the major surface of the windowpane of the article. [Figure 1(b)] 1(a) shows a side view of the embodiment of the article of FIG. 1(a) taken along line A, with a portion of the window frame 20 cut away. [Figure 1(c)] 1(a) shows a side view of the embodiment of the article of FIG. 1(a) including a reflective material as viewed along line of sight A, with a portion of the window frame 20 cut away. DETAILED DESCRIPTION OF THE INVENTION

[0010] Products identified by trade names refer to compositions available under those trade names as of the priority date of this document.

[0011] "Multiple" means two or more. "And / or" means "and, or as an alternative." All ranges are inclusive of the endpoints unless otherwise indicated.

[0012] "Cx~Cy", "C x ~C y "," "C x~y " are interchangeable and refer to compositions having a number of carbon atoms ranging from x to y.

[0013] "Silicon nanoparticles" refer to silicon-based particles having an average particle size of less than 1 micrometer, typically 100 nanometers (nm) or less, but also having an average particle size of 1 nm or greater. Dynamic light scattering or transmission electron microscope image analysis are common methods for determining the average particle size of silicon nanoparticles. Silicon nanoparticles include silicon quantum dots.

[0014] "Silicon-based" refers to a composition that includes silicon. Silicon-based materials generally contain 40 percent (%) or more silicon atoms or a combination of silicon and oxygen atoms relative to the total atoms in the material, and can contain 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or even 100% silicon atoms or a combination of silicon and oxygen atoms.

[0015] "Quantum dot" refers to a nanoscale particle that transports electrons and, when illuminated with photons having energies higher than the bandgap of the quantum dot material, emits light of various wavelengths depending on the properties of the particle.

[0016] "Silicon quantum dots" ("SiQDs") refer to silicon nanoparticles that have a crystalline silicon structure and exhibit photoluminescence when exposed to light. Typically, SiQDs have an average particle size in the range of 1 to 10 nanometers, preferably in the range of 1 to 6 nanometers, and more preferably in the range of 1 to 5 nanometers. Silicon quantum dots are characterized by the fact that they emit light when exposed to light having a wavelength in the wavelength range of 300 to 477 nanometers, which corresponds to blue and ultraviolet light.

[0017] Unless the context of use indicates otherwise, "quantum dots" as used herein refers to any type of quantum dot, including SiQDs.

[0018] "Solar cell" is a term that is used interchangeably with photovoltaic cell and refers to an electronic device that converts the energy of light into electricity through the physical and chemical phenomenon known as the photovoltaic effect.

[0019] "Pane" refers to the portion of a window that typically functions to allow light to penetrate the window while serving to prevent wind and environmental elements such as rain, dust, and pests from penetrating the window. A pane comprises at least one sheet of glazing material. Desirably, a pane is made from one or more sheets of glass.

[0020] "Major surface" refers to the surface of an article having the highest planar surface area, and the surface opposite that surface, if such an opposing surface exists. "Planar surface area" refers to the surface area projected onto a plane to exclude consideration of holes, pits, valleys, or other contours in the surface. "Edge" of an article having opposing major surfaces refers to the surface that separates the opposing major surfaces and extends around the perimeter of the major surfaces.

[0021] "Light-transmitting contact" refers to direct or indirect contact between two or more elements that allows light to be transmitted from one element to another.

[0022] As used herein, "vacuum" refers to an atmosphere with a pressure lower than the atmospheric pressure surrounding the environment described as having a vacuum. For example, a window with a vacuum between its two panes refers to a window with a pressure between the two panes that is lower than the pressure of the atmosphere surrounding the window. Typically, a vacuum has a pressure of less than 101 kiloPascals (kPa), and can be 50 kPa or less, 20 kPa or less, 10 kPa or less, 5 kPa or less, 1 kPa or less, or even 0.1 kPa or less.

[0023] The present invention is an article comprising: (a) a window pane having opposing major surfaces and an edge extending around the major surfaces; (b) a window frame around at least a portion of the edge of the window pane; and (c) a sealant between the window pane and the window frame, wherein the sealant comprises SiQDs.

[0024] window glass The article of the present invention can include a single pane or multiple panes, each having opposing major surfaces and an edge extending around the major surfaces. In the broadest scope of the present invention, there is no limitation on the pane material, but it desirably allows visible light transmission through the pane material. When multiple panes are present, the panes can be the same material or different materials. Examples of suitable pane materials include those comprising glass, polymers (such as organic polymers), or combinations of glass and polymers. Glass includes silicate glasses, such as soda-lime-silica glass and borosilicate glass. Suitable polymers for use as panes include organic polymers, such as polymethylmethacrylate (PMMA) and polycarbonate.

[0025] The window glass can include quantum dots on and / or within the window glass. For example, the polymer window glass can be a polymer film with quantum dots dispersed within the film or coated on the surface of the film. Gallagher et al., Sol. Energy 2007, 81, 813-821, describes a quantum dot solar concentrator suitable for use as a window glass, having quantum dots dispersed in a polyurethane or PMMA sheet. The window glass can have quantum dots adhered to the surface of the window glass, either directly or as a polymer film or coating containing quantum dots adhered to the window glass surface.

[0026] The articles of the present invention can include laminated glass as one or more window panes. Laminated glass includes glass sheets with their respective major surfaces laminated together with a polymer film between the glass sheets. Laminated glass can be a form of "safety glass." Common polymer films between the glass sheets include ethylvinyl acetate (EVA), polyvinyl butyral (PVB), and ionomers. Laminated glass can include quantum dots. For example, the polymer film between the glass sheets of the laminated glass can include quantum dots. For example, U.S. Patent Application Publication No. 2017 / 0341346 discloses a laminated glass luminous concentrator having a specific type of quantum dot in the polymer film between the glass sheets of the laminated glass, and such laminated glass is suitable for use as a window pane in the present invention. In particular, the present invention can include laminated glass having SiQDs in or on the polymer film between the glass sheets of the laminated glass. SiQDs are particularly desirable in such applications due to their temperature stability, which allows them to be included in processes using lamination at temperatures higher than those at which other quantum dots degrade.

[0027] The article of the present invention can be an insulating window comprising two or more panes separated from one another, sealed together, and defining a volume therebetween with a vacuum or insulating gas therein. The vacuum or insulating gas inhibits heat conduction through the panes. Examples of suitable insulating gases include any one or combination of noble gases, such as those selected from the group consisting of argon, krypton, and xenon. The insulating window can comprise quantum dots including SiQDs. The quantum dots can be present within one or more panes of the insulating window. The quantum dots can be present on the surface of one or more panes of the insulating window, preferably on a surface in contact with the volume under vacuum or the volume containing the insulating gas. The quantum dots can be present directly on the surface of the panes or in a polymer film or coating on the surface of the panes.

[0028] The article of the present invention may include multiple panes separated by slats to give the appearance of a grid or lattice.

[0029] window frame The article of the present invention has a window frame. The window frame holds the window pane of the article in place. The window frame is present around at least a portion of the edge of the window pane of the article. When the article includes multiple window panes, the window frame desirably extends around at least a portion of the edge of all of the window panes. Desirably, the window frame extends around the entire edge of the window panes. The window frame typically includes side jambs as vertical portions of the window frame that form the sides of the window frame, and top and bottom rails that form the top and bottom of the window frame, respectively.

[0030] In the broadest scope of the present invention, the construction of the window is not limited. Common materials useful for window frames include wood, plastic, metal, or a combination thereof.

[0031] sealant The article of the present invention comprises a sealant in light-transmitting contact with the edge of one or more panes of glass. The sealant is useful for providing an airtight contact between the pane and a window frame or other element adjacent to the pane. Typically, the article of the present invention comprises a window frame extending entirely around the pane (or combination of panes), with the sealant present between the pane and the window frame to form a seal. The sealant can be present only between a portion of the pane and a portion of the window frame, or it can extend entirely around the pane and frame.

[0032] In the broadest scope of the present invention, the sealant can be any sealant useful for sealing windows, including window sealing tapes, rubber window seals, and caulks. Sealant materials can include silicone caulks, polyurethane caulks, acrylic latex caulks, and butyl rubber caulks. Of particular interest are silicone room temperature vulcanizing (RTV) sealant materials.

[0033] The sealant includes quantum dots. The quantum dots are preferably dispersed within the sealant. Preferably, the quantum dots are dispersed within the sealant, and the sealant is (at least partially) transparent to UV and / or visible light. The quantum dots can be SiQDs, which offer higher thermal stability than many other quantum dots. Furthermore, SiQDs tend to be particularly compatible with silicone caulking compositions, which are one of the most desirable sealants for windows. Preferably, the sealant is a silicone caulking with dispersed SiQDs.

[0034] The concentration of quantum dots in the sealant is not critical to the broadest scope of the invention. The purpose of having quantum dots in the sealant is to capture UV and / or blue light reflecting within and off the edge of the window glass and convert it into light that the solar cell can use to generate electricity. Therefore, a higher concentration of quantum dots in the sealant is desirable. Typically, the concentration of quantum dots in the sealant is 0.1 weight percent (wt%) or more, preferably 1 wt% or more, 5 wt% or more, or even 10 wt% or more, while typically 30 wt% or less, 20 wt% or less, 15 wt% or less, and may be 10 wt% or less.

[0035] The quantum dots can be physically blended into the sealant to obtain the sealant of the present invention. The quantum dots can be dispersed in a liquid carrier and blended with the sealant to facilitate mixing. Any mixing method is suitable, including continuous methods such as extrusion mixing, as well as batch or semi-batch methods such as blender mixing.

[0036] solar cells Desirably, the article of the present invention comprises at least one solar cell in light-transmitting contact with the edge of the window glass and / or the sealant comprising quantum dots, and may comprise two or more solar cells.

[0037] When a solar cell is in light-transmitting contact with the edge of a window glass, the quantum dot-containing sealant is also in light-transmitting contact with a portion of the edge of the window glass. The solar cell collects light transmitted by the window glass to the edge of the window glass and converts the light into electricity. The quantum dots in the sealant desirably emit light at a wavelength that can be converted into electricity by the solar cell. In such a configuration, UV or blue light that exits the edge of the window glass and strikes the quantum dot-containing sealant can be absorbed by the quantum dots in the sealant. The quantum dots can then emit the light back to the edge of the window glass, where it can travel through the window glass to the solar cell, which is in light-transmitting contact with the edge of the window glass. The light from the quantum dots can then be converted into electricity. Desirably, the sealant, with or without quantum dots therein, provides a seal between the window frame and the window glass around the solar cell, which is in light-transmitting contact with the window glass.

[0038] When a solar cell is in light-transmitting contact with the sealant, light emitted by the quantum dots in the sealant can be emitted directly onto the solar cell for conversion to electricity.

[0039] Examples of suitable solar cells include, for example, those made using monocrystalline silicon (m-Si), polycrystalline silicon, amorphous silicon, copper indium gallium selenide (CIGS), and cadmium telluride (CdTe) materials.

[0040] reflective material The article of the present invention can include a reflective material in light-transmitting contact with a portion of the edge of one or more panes of glass. The reflective material may be desirable to reflect light that would otherwise be lost through the edge of the pane back into the pane. Lewo et al., J. Appl. Phys., 2013, 113, 214510, describes the use of reflective panel edges to reduce photon loss from a light-emitting solar concentrator. Such reflective material applications can be applied to the present invention. When present, the reflective material is in light-transmitting contact with a portion of the edge of at least one pane of the article, while the sealant is also in light-transmitting contact with the pane. The article can include a reflective material, a sealant, and at least one solar cell, all of which are in light-transmitting contact with the edge of the pane.

[0041] Examples of suitable reflective materials include metals such as aluminum, silver, and chromium, and compounds such as zinc sulfide and titanium dioxide.

[0042] FIG. 1 shows an exemplary article of the present invention having a window pane 10 with a major surface 15 and a window frame 20 extending around the perimeter of the window pane 10. FIG. 1(a) shows the exemplary article facing the major surface 15 of the window pane 10. FIG. 1(b) and FIG. 1(c) show side views of two embodiments of the article of FIG. 1(a) taken along line of sight A. FIG. 1(b) shows an embodiment having a sealant 30 on the edge of the window pane 10, as well as a solar cell 40 on the edge of the window pane 10. FIG. 1(c) shows an embodiment having a sealant 30, a solar cell 40, and a reflective material 50 at the edge of the window pane 10. The sealant 30 has quantum dots dispersed therein (not shown).

Claims

1. An article, a. a pane having opposing major surfaces and an edge extending around said major surfaces; b. a window frame around at least a portion of the edge of the window pane; c. a sealant in light transmitting contact with the edge of the window pane; The article, wherein the sealant comprises quantum dots.

2. 10. The article of claim 1, wherein the article comprises a plurality of panes, each pane having opposing major surfaces and an edge extending around the major surfaces, the pane frame being around at least a portion of the edge of both panes, and the sealant being between one or both panes and the pane frame.

3. 3. The article of claim 1 or 2, wherein the article further comprises a solar cell in light-transmitting contact with the sealant and / or at least one edge of at least one window pane.

4. The article of any one of claims 1 to 3, wherein the article comprises a reflective material in light-transmitting contact with a portion of one or more edges of a window pane.

5. 5. The article of any one of claims 1 to 4, wherein the quantum dots are (i) dispersed in at least one pane of glass, and / or (ii) dispersed on and / or in a film or coating on a major surface of a pane of glass.

6. The article of any one of claims 1 to 5, wherein the quantum dots are silicon quantum dots.

7. The article of any one of claims 1 to 6, wherein the sealant is a silicone sealant having silicon quantum dots dispersed therein.

8. 8. The article of any one of claims 1 to 7, wherein the article comprises a laminated glass glazing having glass sheets laminated together with a polymer film between the glass sheets, and optionally comprising quantum dots in the polymer film.

9. 9. The article of any one of claims 1 to 8, wherein the article comprises two or more panes separated from one another and defining a volume therebetween, the volumes being sealed and having a vacuum or insulating gas in the volume therebetween, the article optionally further comprising quantum dots in one or more of the panes and / or on a surface of one or more of the panes.

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