WO2014197393A1

WO2014197393A1 - Photostable wavelength conversion composition

Info

Publication number: WO2014197393A1
Application number: PCT/US2014/040553
Authority: WO
Inventors: Yufen HU; Hongxi Zhang; Stanislaw Rachwal; Isamu KITAHARA; Jie Cai; Michiharu Yamamoto
Original assignee: Nitto Denko Corporation
Priority date: 2013-06-04
Filing date: 2014-06-02
Publication date: 2014-12-11

Abstract

This invention relates to compositions used for forming a photostable wavelength conversion material comprising at least one chromophore, at least one optically transparent crosslinkable polymer, and at least one crosslinking reagent. In some embodiments the composition further comprises one or more of an adhesion promoter, a stabilizer, a crosslinker, and/or an antioxidant. The composition for forming a photostable wavelength conversion material can be formed into a film or layer. The film or layer is useful as an encapsulate for solar energy devices as it provides stable enhancement of the photoelectric conversion efficiency of these devices by converting photons from one wavelength into a different more desirable wavelength that can be more efficiently utilized by the solar energy device. Simultaneously, the film or layer, when used in an encapsulation structure, also provides stable long term environmental protection to the solar energy device from oxygen and water ingress as well as protection from harmful high energy ultraviolet photons. The film or layer is also useful as a greenhouse roofing material.

Description

PHOTOSTABLE WAVELENGTH CONVERSION COMPOSITION

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims the benefit of priority to U.S. Provisional Patent Application No. 61/831 ,074, filed June 4, 2013. The foregoing application is fully incorporated herein by reference for all purposes.

BACKGROUND OF THE INVENTION

Field of the Invention

[0002] Embodiments disclosed herein generally relate to devices and methods of making and using photostable wavelength conversion materials comprising crosslinked polymers.

Description of the Related Art

[0003] The utilization of solar energy offers a promising alternative energy source to the traditional fossil fuels, and therefore, the development of devices that can convert solar energy into electricity, such as photovoltaic devices (also known as solar cells), has drawn significant attention in recent years. Several different types of mature photovoltaic devices have been developed, including a Silicon based device, a III-V and II- VI PN junction device, a Copper-Indium-Gallium-Selenium (CIGS) thin film device, an organic sensitizer device, an organic thin film device, and a Cadmium Sulfide/Cadmium Telluride (CdS/CdTe) thin film device, to name a few. However, the photoelectric conversion efficiency of many of these devices still has room for improvement and development of techniques to improve this efficiency has been an ongoing challenge for many researchers.

[0004] Recently, one technique developed to improve the efficiency of photovoltaic devices is to utilize a wavelength down-shifting film. However, many of the photovoltaic devices are unable to effectively utilize the entire spectrum of light as the materials on the device absorb certain wavelengths of light (typically the shorter UV wavelengths) instead of allowing the light to pass through to the photoconductive material layer where it is converted into electricity.

[0005] Wavelength down-shifting is often observed in the thin film CdS/CdTe and CIGS solar cells which both use CdS as the window layer. The low cost and high efficiency of these thin film solar cells has drawn significant attention in recent years, with typical commercial cells having photoelectric conversion efficiencies of 10-16%. However, the energy gap of CdS, approximately 2.41 eV, which causes light at wavelengths below 514 nm to be absorbed by CdS instead of passing through to the photoconductive layer where it can be converted into energy. This inability to utilize the entire spectrum of light effectively reduces the overall photoelectric conversion efficiency of the device.

[0006] There have been reports disclosing the utilization of a wavelength downshifting material to improve the performance of photovoltaic devices. For example, a silicon based solar cell which contains a wavelength down-shifting inorganic phosphor material, an integrated solar cell comprising a plasmonic layer, a wavelength conversion layer, and a photovoltaic layer, a solar cell with a wavelength conversion layer containing a quantum dot compound, and a film made in the form of a thin film polymer comprising an inorganic fluorescent powder have been made.

[0007] The use of wavelength conversion films in greenhouse roofing materials to alter the incident solar spectrum plants are exposed to within a greenhouse has been attempted.

SUMMARY OF THE INVENTION

[0008] Some embodiments provide a wavelength conversion composition. In some embodiments, the wavelength conversion composition can be used to form a photostable wavelength conversion material. In some embodiments, the composition comprises a first organic chromophore, a first optically transparent crosslinkable polymer, and a first crosslinking reagent.

[0009] Any of the embodiments described above, or described elsewhere herein, can include one or more of the following features.

[0010] In some embodiments, the first crosslinking reagent comprises an organic peroxide. In some embodiments, the organic peroxide is selected from the group consisting of diacyl peroxides, dialkyl peroxides, diperoxyketals, hydroperoxides, ketoneperoxides, peroxydicarbonates, and peroxyesters.

[0011] In some embodiments, the first crosslinking reagent is selected from the group consisting of Perbutyl E, Perhexa HC, Perhexa 25B, Percumyl D, Perhexa C, Perhexa V, and Perbutyl P. In some embodiments, the first crosslinking reagent is present in an amount in the range of about 0.1% to about 2.0% by weight of the composition.

[0012] In some embodiments, the composition further comprises a second crosslinking reagent. In some embodiments, the second crosslinking reagent is present in an amount in the range of about 0.1% to about 2.0% by weight of the composition. In some embodiments, the second chromophore is independently selected from the group consisting of Perbutyl E, Perhexa HC, Perhexa 25B, Percumyl D, Perhexa C, Perhexa V, and Perbutyl P.

[0013] In some embodiments, the first optically transparent crosslinkable polymer is selected from the group of polymers consisting of lonomer, thermoplastic polyurethane, thermoplastic polyolefin, polymethyl methacrylate, polyvinyl butyral, polydimethyl silicon, ethylene-methyl methacrylate, and ethylene vinyl acetate.

[0014] In some embodiments, the composition further comprises a second optically transparent crosslinkable polymer. In some embodiments, the second optically transparent crosslinkable polymer is selected from the group consisting of lonomer, thermoplastic polyurethane, thermoplastic polyolefin, polymethyl methacrylate, polyvinyl butyral, polydimethyl silicon, ethylene-methyl methacrylate, and ethylene vinyl acetate.

[0015] In some embodiments, the first optically transparent crosslinkable polymer comprises a host polymer. In some embodiments, the wavelength conversion material further comprises a co-polymer. In some embodiments, the wavelength conversion material comprises multiple polymers.

[0016] In some embodiments, the refractive index of the first optically transparent crosslinkable polymer is in the range of about 1.4 to about 1.7.

[0017] In some embodiments, the composition further comprises a first crosslinking compound. In some embodiments, the first crosslinking compound is selected from the group consisting of trifunctional acrylate, trifunctional methacrylate, zinc diacrylate, zinc dimethacrylate, and N-N'm-phenylene dimaleimide. In some embodiments, the first crosslinking compound is a methacrylate. In some embodiments, the first crosslinking compound is selected from the group consisting of ethylene glycol dimethacrylate, trimethyl propane trimethacrylate, Zinc diacrylate, Zinc dimethacrylate, triallyl cyanurate, triallyl isocyanurate, and high vinyl poly (butadiene). In some embodiments, the first crosslinking compound is a hybrid crosslinker comprising polybutadiene diacrylate. In some embodiments, the first crosslinking compound is present in an amount in the range of about 0.01 % to about 10.0% by weight of the composition.

[0018] In some embodiments, the composition further comprises a second crosslinking compound. In some embodiments, the second crosslinking compound is independently selected from the group consisting of ethylene glycol dimethacrylate, trimethyl propane trimethacrylate, Zinc diacrylate, Zinc dimethacrylate, triallyl cyanurate, triallyl isocyanurate, and high vinyl poly(butadiene).

[0019] In some embodiments, the first organic chromophore is present in an amount in the range of about 0.01 wt% to about 3.0 wt%. In some embodiments, the first chromophore is selected from the group consisting of a perylene derivative dye, a benzotriazole derivative dye, and a benzothiadiazole derivative dye.

[0020] In some embodiments, the first chromophore is represented by the following general formula (I):

wherein Ri, R₂, and R₃ comprise and alkyl, a substituted alkyl, or an aryl.

[0021] In some embodiments, the composition further comprises a second chromophore. In some embodiments, the second chromophore can be selected from any chromophore disclosed below.

[0022] In some embodiments, the composition further comprises 1 , 2, 3, 4, 5, or more additional chromophores. In some embodiments, the additional chromophore(s) can be selected from any chromophore disclosed below.

[0023] In some embodiments, the composition further comprises a first adhesion promoter. In some embodiments, the first adhesion promoter comprises acrylic silane material, vinyl silane material, epoxy silane material, or amino silane material. In some embodiments, the first adhesion promoter comprises a methacrylate silane material. In some embodiments, the first adhesion promoter comprises 3-Methacryloxypropyltrimethoxysilane. In some embodiments, the first adhesion promoter is present in an amount in the range from about 0.001 % to about 2.0% by weight of the composition.

[0024] In some embodiments, the composition comprises a second adhesion promoter. In some embodiments, the second adhesion promoter can be selected from any adhesion promoter disclosed below.

[0025] In some embodiments, the composition further comprises a first stabilizer. In some embodiments, the first stabilizer is a photostabilizer. In some embodiments, the first stabilizer is a hindered amine. In some embodiments, the first stabilizer is a chromophore. In some embodiments, the first stabilizer is selected from the group consisting of Tinuvin 144, Tinuvin 292, Tinuvin 622, Chimassorb 1 19, Chimassorb 944, Tinuvin 770, Tinuvin 791 , Tinuvin 783, Tinuvin 1 1 1 , and Tinuvin NOR371. In some embodiments, the first stabilizer is present in an amount in the range of about 0.001% to about 2.0% by weight of the composition.

[0026] In some embodiments, the composition further comprises a second stabilizer.

[0027] In some embodiments, the composition further comprising a first antioxidant. In some embodiments, the first antioxidant is selected from the group consisting of a phenolic antioxidant, a phosphite antioxidant, and a theoether antioxidant. In some embodiments, the first antioxidant is selected from the group consisting of Irganox 1010, Irganox 1076, Irgfos 168, butylated hydroxytoluene, Irganox PS 800, and Irganox PS802. In some embodiments, the first antioxidant is present in an amount in the range of about 0.001 % to about 0.5% by weight of the composition.

[0028] In some embodiments, the composition further comprises a second antioxidant. In some embodiments, the first antioxidant and the second antioxidant are independently selected from the group consisting of a phenolic antioxidant, a phosphite antioxidant, a theoether antioxidant, Irganox 1010, Irganox 1076, Irgfos 168, butylated hydroxytoluene, Irganox PS 800, and Irganox PS802. [0029] In some embodiments, the composition further comprises an IR reflective agent. In some embodiments, the IR reflective agent is selected from the group consisting of metal oxide, mica powder, composite oxide, Talc, titania, ceria, zirconia, silica, magnesia, clay, Kaolin, alumina, infrared pigment, and combinations thereof. In some embodiments, the IR reflective agent is present in an amount of in the range of about 0.01 % to about 30% by weight of the composition.

[0030] In some embodiments, the composition further comprises one or more of an IR absorber, an anti-fog agent, an anti-mist agent, an anti-drop agent, anti-dust agent, a lubricant, a modifier, an inorganic filler, and an anti-static agent.

[0031] Some embodiments pertain to a wavelength conversion layer formed by curing any one of the above disclosed compositions. In some embodiments, the composition is cured at a temperature of between about 130 to about 180 degrees Celsius to form the wavelenther conversion layer. In some embodiments, the layer is cured for a time ranging from about 5 to about 100 minutes.

[0032] Some embodiments pertain to an encapsulation structure for a solar energy conversion device comprising a wavelength conversion layer as described above, wherein the wavelength conversion layer is configured to encapsulate a solar energy conversion device and inhibit penetration of moisture and oxygen into the solar energy conversion device, and wherein the wavelength conversion layer is configured to encapsulate the solar energy conversion device such that light must pass through the wavelength conversion layer prior to reaching the solar energy conversion device.

[0033] Some embodiments pertain to an encapsulation structure for a solar energy conversion device comprising a wavelength conversion layer as described above, an environmental protective cover configured to inhibit penetration of moisture and oxygen into the wavelength conversion layer and the solar energy conversion device, and wherein the wavelength conversion layer and the environmental protective cover are configured to encapsulate the solar energy conversion device such that light must pass through the wavelength conversion layer and the environmental protective cover prior to reaching the solar energy conversion device. In some embodiments, the environmental protective cover comprises glass or polymer sheets. In some embodiments, the encapsulation structure for a solar energy conversion device further comprises a sealing tape around the perimeter of the solar energy conversion device. In some embodiments, the encapsulation structure further comprises one or more of a glass sheet, a reflective backsheet, edge sealing tape, a framing material, a polymer encapsulation material, or an adhesive layer to adhere additional layers to the system. In some embodiments, the encapsulation structure further comprises an additional polymer layer containing a UV absorber, an antioxidant, or any combination thereof.

[0034] Some embodiments pertain to a method of improving the performance of a solar energy conversion device, comprising encapsulating the device with the encapsulation structure described above. In some embodiments, the solar energy conversion device contains at least one device selected from the group consisting of a III-V or II- VI PN junction device, a Copper-Indium-Gallium-Selenium (CIGS) thin film device, an organic sensitizer device, an organic thin film device, a Cadmium Sulfide/Cadmium Telluride (CdS/CdTe) thin film device, an amorphous Silicon solar cell, a microcrystalline Silicon solar cell, a polycrystalline Silicon solar cell, and a crystalline Silicon solar cell.

[0035] Some embodiments pertain to a composition for producing a photostable wavelength conversion material for a solar energy conversion device comprising a first chromophore, a first optically transparent crosslinkable polymer, and a first crosslinking reagent, with the proviso that the chromophore is not within an oxide microparticle. In some embodiments, the wavelength conversion layer is formed by curing the above composition.

[0036] Some embodiments pertain to a composition for producing a photostable wavelength conversion material for a solar energy conversion device comprising a first chromophore, a first optically transparent crosslinkable polymer, and a first crosslinking reagent, wherein the at least one chromophore is a UV absorber. Some embodiments pertain to a wavelength conversion layer formed by curing a composition containing the UV absorber.

[0037] Some embodiments pertain to a composition for forming a photostable wavelength conversion material for a solar energy conversion device comprising a first organic chromophore, a first monomer, wherein upon polymerization the monomer yields an optically transparent crosslinkable polymer, and a first crosslinking reagent.

[0038] Some embodiments pertain to a greenhouse panel comprising at least one wavelength conversion layer as described above. A greenhouse solar collection panel comprising at least one wavelength conversion layer as described above and at least one solar energy conversion device.

[0039] A method of making a wavelength conversion layer comprising curing any of the wavelength conversion compositions described above. In some embodiments, the curing step is performed at a temperature of between about 130 to about 180 degrees Celsius. In some embodiments, the layer is cured for a time ranging from about 5 to about 100 minutes.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 illustrates an embodiment of a device where a single solar cell device is encapsulated in the wavelength conversion composition and glass or polymer sheets are used as an environmental protective cover.

[0041] Figure 2 illustrates an embodiment of a device where a plurality of solar cell devices are encapsulated in the wavelength conversion composition and glass or polymer sheets are used as an environmental protective cover.

[0042] Figure 3 illustrates an embodiment of a device where a plurality of solar cell devices are encapsulated in a pure polymer encapsulate, the wavelength conversion composition is laminated on top of the polymer encapsulate, and glass or polymer sheets are used as an environmental protective cover.

[0043] Figure 4 illustrates an embodiment of a device where a plurality of solar cell devices are encapsulated in the wavelength conversion composition and glass or polymer sheets are used as an environmental protective cover.

[0044] Figure 5 illustrates an embodiment of a device where a plurality of solar energy conversion devices are encapsulated in a pure polymer encapsulate, the wavelength conversion composition is laminated on top of the polymer encapsulate, and glass or polymer sheets are used as an environmental protective cover.

[0045] Figure 6 illustrates an embodiment of a device where a plurality of solar energy conversion devices are encapsulated in a pure polymer encapsulation material, the wavelength conversion composition is laminated on top of the pure polymer encapsulate, an additional polymer film is laminated on top of the wavelength conversion composition, and glass or polymer sheets are used as environmental protector. [0046] Figure 7 illustrates an embodiment of a device where a single solar cell device is encapsulated in the wavelength conversion composition, and the wavelength conversion composition also acts as an environmental protector.

[0047] Figure 8 illustrates an embodiment of a device where a plurality of solar cell devices are encapsulated in the wavelength conversion composition, and the wavelength conversion composition also acts as an environmental protector.

[0048] Figure 9 illustrates an embodiment of a device where a plurality of solar cell devices are encapsulated in a polymer encapsulation material, the wavelength conversion composition is laminated on top of the polymer encapsulate, and the wavelength conversion composition also acts as an environmental protector.

[0049] Figure 10 illustrates an example embodiment of a device where a solar panel with several solar cell devices utilizes a wavelength conversion composition to encapsulate the solar cell devices, a glass bottom sheet and a glass top sheet provide environmental protection, a back sheet is underneath the light incident surface of the solar cell devices, and a frame holds the panel together.

[0050] Figure 1 1 illustrates an example embodiment of a device where a solar panel with several solar cell devices utilizes a wavelength conversion composition to encapsulate the solar cell devices, a back sheet is underneath the light incident surface of the solar cell devices, a glass top sheet provides environmental protection, and a frame holds the panel together.

[0051] Figure 12 illustrates an embodiment of a greenhouse panel comprising a wavelength conversion layer with two organic photostable chromophores, wherein the wavelength conversion layer is formed by curing a layer of the composition for forming a photostable wavelength conversion material.

[0052] Figure 13 illustrates an embodiment of a greenhouse panel comprising two wavelength conversion layers, wherein each wavelength conversion layer comprises a different organic photostable chromophore, and wherein each wavelength conversion layer is formed by curing a layer of the composition for forming a photostable wavelength conversion material.

[0053] Figure 14 illustrates an embodiment of a greenhouse panel comprising two wavelength conversion layers, wherein each wavelength conversion layer comprises a different organic photostable chromophore, wherein each wavelength conversion layer is formed by curing a layer of the composition for forming a photostable wavelength conversion material, and wherein the greenhouse panel further comprises a glass plate.

[0054] Figure 15 illustrates an embodiment of a greenhouse solar collection panel comprising two wavelength conversion layers, wherein each wavelength conversion layer comprises a different organic photostable chromophore, wherein each wavelength conversion layer is formed by curing a layer of the composition for forming a photostable wavelength conversion material, and wherein the greenhouse solar collection panel further comprises glass plates and at least one solar energy conversion device.

[0055] Figure 16 shows the normalized absorption of the Example 1 testing device after 5000 hours (-30 weeks) exposure to accelerated solar irradiation.

[0056] Figure 17 shows the normalized absorption of the Example 2 testing device after 3500 hours (-20 weeks) exposure to accelerated solar irradiation.

[0057] Figure 18 shows the normalized absorption of the Example 3 (140Cx35min), Example 4 (155Cxl0min), and Example 5 (145Cx25min) testing devices, which use the Perhexa C crosslinking reagent, after 1500 hours (-9 weeks) exposure to accelerated solar irradiation.

[0058] Figure 19 shows the normalized absorption of the Example 6 (155Cx45min), Example 7 (155Cxl05min), and Example 8 (160Cx65min) testing devices, which used the Perhexa 25B crosslinking reagent, after 1500 hours (-9 weeks) exposure to accelerated solar irradiation.

[0059] Figure 20 shows the normalized absorption of the Example 9 testing device, when the Tinuvin 144 concentration was increased, after 1000 hours exposure to accelerated solar irradiation.

[0060] Figure 21 shows the normalized absorption of the Example 10 (chromophore 1), Example 1 1 (chromophore 2), and Example 12 (chromophore 3), testing devices, which used different chromophore compounds, after 1250 hours exposure to accelerate solar irradiation.

[0061] Figure 22 shows the normalized absorption of the Example 13 (EVA + Chromophore 4 + additives) and Example 14 (EVA + Chromophore 4), after 3000 hours exposure to accelerated solar irradiation. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0062] Currently, wavelength conversion layers are applied directly on top of or into the solar cell device, which adds additional cost to manufacturing the devices and increases the device thickness which leads to lower solar cell efficiency. Furthermore, solar modules are traditionally mounted outdoors on rooftops or in wide-open spaces where they can maximize their exposure to sunlight. This type of outdoor placement subjects these devices to constant weather and moisture exposure, and therefore, they must have sufficient protection to provide many years of stable operation. Traditionally, solar cell modules have been weatherproofed by using glass sheets, which is expensive, heavy, and rigid, and also requires some type of edge tape to prevent moisture from penetrating the sides. However, attempts to simultaneously provide environmental protection for the solar devices as well as enhanced solar harvesting efficiency have not been made.

[0063] Current encapsulation materials for solar energy devices do not utilize chromophore compounds to enhance efficiency because of their rapid photo degradation rates. Additionally, the current commercially available encapsulation materials typically comprise polymer compounds that turn yellow with exposure to sunlight, which, in turn, causes a decrease in the photoelectric conversion efficiency due to the decreased transmission of the photons into the solar energy conversion device.

[0064] The use of wavelength conversion films in greenhouse roofing materials in current systems lack efficiency and stability. For instance, current systems lose a large amount of the emitted light to the polymeric or glass matrix which encapsulates the dyes. Also, the stability of the dyes is poor and the dyes often degrade quickly, especially when exposed to UV light.

[0065] Because of high cost and low efficiency/stability, there remains an unmet need for wavelength conversion films that provide environmental protection for the solar devices as well as enhanced solar harvesting efficiency. There is also an unmet need for wavelength conversion films (in greenhouse and agricultural applications) that, for example, improve plant growth, are photostable, and can be used to improve solar energy harvesting simultaneously. [0066] Embodiments of the present disclosure relate to compositions for forming photostable wavelength conversion materials wherein the photostable wavelength conversion material is highly stable under long term solar irradiation.

[0067] Embodiments of the disclosure provide compositions for forming photostable wavelength conversion materials wherein the photostable wavelength material provides both wavelength conversion enhancement from a highly photostable chromophore, and also provide highly stable transmission with no yellowing. When compared to current commercially available wavelength conversion materials, the wavelength conversion materials disclosed herein, show very good photostability with exposure to solar radiation over long periods of time. Thus, the wavelength conversion materials disclosed herein are useful as an encapsulation material for solar energy harvesting devices and/or as a greenhouse roofing material.

[0068] Some embodiments disclosed herein provide compositions for forming a photostable wavelength conversion material. In some embodiments, the composition for forming a photostable wavelength conversion material comprises a first chromophore, a first optically transparent crosslinkable polymer, and a first crosslinking reagent. In some embodiments, the composition for forming a photostable wavelength conversion material further comprises a first adhesion promoter, a first stabilizer, and/or a first crosslinker.

[0069] The composition for forming a photostable wavelength conversion material may be cured to provide a photostable wavelength conversion material. In some embodiments, the photostable wavelength conversion material can be molded to form a wavelength conversion layer. In some embodiments, the wavelength conversion layer may be incorporated into an encapsulation structure for solar energy devices. Because the photostable wavelength conversion material is stable for long periods of time when exposed to solar irradiation, it is highly suitable to provide solar energy devices with protection from the environment. Additionally, the photostable wavelength conversion material also converts incoming photons of one wavelength into a different more desirable wavelength which can be more efficiently converted into electricity by the solar energy conversion device. Therefore, by employing the photostable wavelength conversion material to encapsulate solar energy conversion devices, the photoelectric conversion efficiency of these devices can be improved. Solar energy conversion devices include solar cells, solar panels, photovoltaic devices, or any solar module system.

[0070] Encapsulation of solar energy conversion devices with encapsulation structures comprising the photostable wavelength conversion materials, as disclosed herein, enhances the solar harvesting efficiency of the solar cell device, and provides stable long term environmental protection of the device. The encapsulation structures comprising the wavelength conversion compositions disclosed herein are compatible with all different types of solar cells and solar panels, including Silicon based devices, III-V and II-VI PN junction devices, CIGS thin film devices, organic sensitizer devices, organic thin film devices, CdS/CdTe thin film devices, dye sensitized devices, etc.

[0071] Various organic peroxides may be used in the composition. In some embodiments, the peroxide comprises a crosslinking reagent. The particular peroxide that is used may be selected to be compatible with the particular components of the wavelength conversion composition. In some embodiments, the peroxide added to the composition provides an increase in the photostability of the composition after crosslinking.

[0072] In some embodiments, the first crosslinking reagent comprises a peroxide. In some embodiments, the first crosslinking reagent comprises an organic peroxide. In some embodiments, the peroxide is selected from diacyl peroxides, dialkyl peroxides, diperoxyketals, hedroperoxides, ketoneperoxides, peroxydicarbonates, and peroxyesters. In some embodiments, the peroxide is selected from the group consisting of l ,l -di(t- butylperoxy)cyclohexane (Perhexa C), l ,l-di(t-hexyperoxy)cyclohexane (Perhexa HC), t- butyl peroxy 2-ethylhexyl monocarbonate (Perbutyl E), n-butyl 4,4-di(t-butyl peroxy) valerate (Perhexa V), Di(2-t-butylperoxy isopropyl) benzene (Perbutyl P), 2,5-dimethyl-2,5- di(t-butylperoxy)hexane (Perhexa 25B), and dicumyl peroxide (Percumyl D).

[0073] In some embodiments, the concentration of the first crosslinking reagent in the composition for forming a photostable wavelength conversion material may also be determined based on the particular components and the desired properties. In some embodiments, it is desired for the first crosslinking reagent to be completely reacted during the crosslinking reaction, such that none of the at least one crosslinking reagent remains in the composition after forming a photostable wavelength conversion material after crosslinking. In some cases, if too much peroxide, for example, is used in the composition prior to crosslinking, the remaining peroxide will react with the chromophore and can decrease the photostability of the composition. Typically the use of the peroxide in the composition enables the crosslinking to occur, and increases the photostability of the wavelength conversion composition. If too little peroxide is used in the composition, then the crosslinking reaction will not occur.

[0074] In some embodiments, the first crosslinking reagent is present in an amount in the range of about 0.01% to about 3.0% by weight of the composition. In some embodiments, the first crosslinking reagent is present in an amount in the range of about 0.1 % to about 2.0% by weight of the composition. In some embodiments, the first crosslinking reagent is present in the wavelength conversion composition in an amount in the range from about 0.01 % to about 0.1%, from about 0.1% to about 1.0%, from about 1.0% to about 2.0%, or from about 2.0% to about 3.0% by weight of the composition. In some embodiments, the first crosslinking reagent is present in the wavelength conversion composition in an amount in the range from about 0.01% to about 3.0%, from about 0.1% to about 2.0%, or from about 1.0% to about 2.0% by weight of the composition.

[0075] As used herein, "about" means approximately. The term "about" may refer to, for example, values that are ± 0.0%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 10.0% relative to the value modified by the term "about." For example, "about 10" where "about" represents 5.0% variability is equivalent to a value of "10 ± 0.5." In some instances, "about" may represent variability greater than ± 10.0%.

[0076] In some embodiments, the composition for forming a photostable wavelength conversion material comprises a second crosslinking reagent in combination with the first crosslinking reagent. In some embodiments, the second crosslinking reagent is as defined above. In some embodiments, the second crosslinking reagent comprises a peroxide. For instance, in some embodiments, the second crosslinking reagent comprises an organic peroxide. In some embodiments, the peroxide is selected from diacyl peroxides, dialkyl peroxides, diperoxyketals, hedroperoxides, ketoneperoxides, peroxydicarbonates, and peroxyesters. In some embodiments, the peroxide is selected from the group consisting of 1 , 1 -di(t-butylperoxy)cyclohexane (Perhexa C), l ,l -di(t-hexyperoxy)cyclohexane (Perhexa HC), t-butyl peroxy 2-ethylhexyl monocarbonate (Perbutyl E), n-butyl 4,4-di(t-butyl peroxy) valerate (Perhexa V), Di(2-t-butylperoxy isopropyl) benzene (Perbutyl P), 2,5-dimethyl-2,5- di(t-butylperoxy)hexane (Perhexa 25B), and dicumyl peroxide (Percumyl D). In some embodiments, the second crosslinking reagent may be in any combination with the first crosslinking reagent.

[0077] In some embodiments, the second crosslinking reagent is present in an amount in the range of about 0.01% to about 3.0% by weight of the composition. In some embodiments, the second crosslinking reagent is present in an amount in the range of about 0.1% to about 2.0% by weight of the composition. In some embodiments, the second crosslinking reagent is present in the wavelength conversion composition in an amount in the range from about 0.01 % to about 0.1%, from about 0.1% to about 1.0%, from about 1.0% to about 2.0%, or from about 2.0% to about 3.0% by weight of the composition. In some embodiments, the second crosslinking reagent is present in the wavelength conversion composition in an amount in the range from about 0.01% to about 3.0%, from about 0.1% to about 2.0%, or from about 1.0% to about 2.0% by weight of the composition.

[0078] In some embodiments, the composition comprises 1 , 2, 3, 4, 5, 6, or more additional crosslinking reagents. The crosslinking reagents may be as defined above (e.g., a "peroxide," etc.) or otherwise and may be in any combination with the first and second crosslinking reagents.

[0079] In some embodiments, the total amount of the crosslinking reagent in the photostable wavelength conversion material is in the range of about 0.01 % to about 3.0% by weight of the composition for forming a photostable wavelength conversion material. In some embodiments, the total amount of the crosslinking reagent in the photostable wavelength conversion material is in the range from about 0.01% to about 6.0%, from about 0.1% to about 5.0%, from about 1.0% to about 4.0%, or from about 2.0% to about 3.0% by weight of the composition.

[0080] In some embodiments, the first optically transparent crosslinkable polymer is selected from the group consisting of Ionomer, thermoplastic polyurethane (TPU), thermoplastic polyurethanethermoplastic polyolefin (TPO), polymethyl methacrylate (PMMA), polyvinyl butyral (PVB), polydimethyl silicone (PDMS), ethylene-methyl methacrylate (EMMA), and ethylene vinyl acetate (EVA). In some embodiment, an optically transparent crosslinkable polymer is a polymer that is optically transparent after crosslinking. [0081] The refractive index of the first optically transparent polymer may vary. In some embodiments the refractive index of the first optically transparent crosslinkable polymer is in the range of about 1.4 to about 1.7. In some embodiments, the refractive index of the first optically transparent crosslinkable polymer is in the range of about 1.45 to about 1.55.

[0082] In some embodiments, the composition for forming a photostable wavelength conversion material comprises a second optically transparent crosslinkable polymers in combination with the first optically transparent crosslinkable polymer. In some embodiments, the second additional optically transparent crosslinkable polymer is as defined above. For example, in some embodiments, the second optically transparent crosslinkable polymer is selected from the group consisting of Ionomer, thermoplastic polyurethane (TPU), thermoplastic polyurethanethermoplastic polyolefin (TPO), polymethyl methacrylate (PMMA), polyvinyl butyral (PVB), polydimethyl silicone (PDMS), ethylene-methyl methacrylate (EMMA), and ethylene vinyl acetate (EVA). In some embodiments, the first and second optically transparent crosslinkable polymers are independently selected from the above polymer and may be in any combination.

[0083] In some embodiments, the composition comprises 1 , 2, 3, 4, 5, 6, or more additional optically transparent crosslinkable polymers. The optically transparent crosslinkable polymers may be as defined above (e.g. Ionomer, etc.) or otherwise and may be in any combination with the first and second crosslinking reagents.

[0084] The refractive index of the one or more additional optically transparent crosslinkable polymers may vary. In some embodiments the refractive index of each of the first, second, or more additional optically transparent crosslinkable polymers is in the range of about 1.4 to about 1.7. In some embodiments the refractive index of each of the first, second, or more additional optically transparent crosslinkable polymers is in the range of of about 1.45 to about 1.55. In some embodiments, the refractive index of the first, second, and/or more additional optically transparent crosslinkable polymers, together, is is in the range of about 1.4 to about 1.7, or about 1.45 to about 1.55.

[0085] In some embodiments, the optically transparent crosslinkable polymer comprises one host polymer. In some embodiments, the optically transparent crosslinkable polymer comprises a host polymer and a co-polymer. In some embodiments, the optically transparent crosslinkable polymer comprises multiple polymers. Those skilled in the art will appreciate that the use of the term "polymer" herein includes copolymers.

[0086] In some embodiments, monomer precursors that polymerize to form optically transparent crosslinkable polymers may be used to form the composition instead of optically transparent crosslinkable polymers. These monomers can be substituted for or used in combination with the optically transparent crosslinkable polymers in the composition for forming a photostable wavelength conversion material. The monomers for forming such polymers are appreciated by those of ordinary skill in the art. The monomers include, for example, monomers capable of forming the optically transparent crosslinkable polymers described above. Crosslinkers or coagents are classified based on their contributions to cure and thus divided into two basic types. Type I coagents increase both the rate and state of cure. Type I coagents are typically polar, low molecular weight multifunctional compounds which propagate very reactive radicals through addition reactions. These "monomers" can be homopolymerized or grafted to polymer chains. Type I coagents include multifunctional acrylate and methacrylate esters and phenylene dimaleimide (PDM). The zinc salts of acrylic (ZD A) and methacrylic acid (ZDMA) also belong to this class.

[0087] Type II coagents form less reactive radicals and contribute only to the state of cure. They form radicals primarily through hydrogen abstraction. Type II coagents can include allyl-containing cyanurates, isocyanurates and phthalates, homopolymers of dienes, and co-polymers of dienes and vinyl aromatics.

[0088] Hybrid coagents have also been developed which have structural components of both Type I and Type II coagents. Depending on the structure of the hybrid coagent, its performance may be similar to Type I coagents, Type II coagents, or a combination thereof.

[0089] In some embodiments, a first crosslinker may be used in the composition for forming the photostable wavelength conversion material. Crosslinkers, can be used to control the elastic modulus (and degree of crosslinking) of the composition. Coagents can also be used to control the elastic modulus (and degree of crosslinking) of the composition. These crosslinkers and coagents may also help increase the physical and/or mechanical strength and/or the photostability of the composition once it is prepared for use as a wavelength conversion material. In some embodiments, a nonmetallic Type I crosslinker and/or a Type II crosslinker is used in the composition for forming a photostable wavelength conversion material. In some embodiments, the Type I crosslinkers include trifunctional acrylate, trifunctional methacrylate, zinc diacrylate, zinc dimethacrylate, and N-N'm- phenylene dimaleimide. In some embodiments, a Type II crosslinker is used in the composition for forming a photostable wavelength conversion material. In some embodiments, the Type II crosslinkers include triallyl cyanurate (TAC), triallyl isocyanurate (TAIC) and high vinyl poly(butadiene) (HVPBD). In some embodiments, HVPBD may be functionalized with maleic anhydride.

[0090] In some embodiments, the first crosslinker can be a hybrid crosslinker. In some embodiments, the hybrid crosslinker is polybutadiene diacrylate (PBDDA).

[0091] In some embodiments, the first crosslinker comprises an acrylate -based crosslinker. In some embodiments, the first crosslinker comprises a methacrylate-based crosslinker. In some embodiments, the first crosslinker is selected from the group consisting of trifunctional acrylate, trifunctional methacrylate, zinc diacrylate, zinc dimethacrylate, and N-N'm-phenylene dimaleimide. In some embodiments, the first crosslinker is selected from the group consisting of ethylene glycol dimethacrylate, trimethyl propane trimethacrylate, Zinc diacrylate, Zinc dimethacrylate, triallyl cyanurate, triallyl isocyanuate, and high vinyl poly(butadiene).

[0092] In some embodiments, the composition for forming a photostable wavelength conversion material comprises a second crosslinker in combination with the first crosslinker. In some embodiments, the second crosslinker is a crosslinker as defined above for the first crosslinker (e.g., the second crosslinker can be ethylene glycol dimethacrylate, etc.) and is independently selected from the crosslinkers described above. Thus, any combination of a first and second crosslinker is envisioned.

[0093] In some embodiments, a mixture of Type I, Type II, and/or hybrid crosslinkers are used in the composition for forming a photostable wavelength conversion material. For example, in some embodiments the wavelength conversion composition comprises between about 0.01wt% to about 10.0wt% of trimethyl propane trimethacrylate, and between about 0.01wt% to about 10.0wt% of triallyl isocyanuate.

[0094] In some embodiments, the composition comprises 1 , 2, 3, 4, 5, 6, or more additional crosslinkers. The additional crosslinkers may be as defined above for the first crosslinker (e.g. PBDDA, etc.) or otherwise and may be in any combination with the first and second crosslinkers.

[0095] Various concentrations of the crosslinker may be used in the composition, depending on the desired properties of the film. In some embodiments, the first or second crosslinker can be present in the wavelength conversion composition individually in an amount in the range from about 0.01 % to about 10.0%, from about 0.1% to about 8.0%, from about 1.0% to about 6.0%, or from about 2.0% to about 4.0% by weight of the composition. In some embodiments, the first or second crosslinker can be present in the wavelength conversion composition individually in an amount in the range from about 0.01 % to about 0.1%, from about 0.1% to about 1.0%, from about 1.0% to about 2.0%, from about 2.0% to about 4.0%, from about 4.0% to about 6.0%, from about 6.0% to about 8.0%, or from about 8.0% to about 10.0% by weight of the composition.

[0096] In some embodiments, the total amount of crosslinker in the photostable wavelength conversion material is in the range from about 0.01% to about 20.0%, from about 0.1% to about 16.0%, from about 1.0% to about 12.0%, or from about 2.0% to about 8.0% by weight of the composition for forming the photostable wavelength conversion material. In some embodiments, the total amount of crosslinker in the photostable wavelength conversion material is in the range from about 0.01 % to about 0.1%, from about 0.1 % to about 1.0%, from about 1.0% to about 2.0%, from about 2.0% to about 4.0%, from about 4.0% to about 6.0%, from about 6.0% to about 8.0%, from about 8.0% to about 10.0%, from about 10.0% to about 15.0%, or from about 15.0% to about 20.0% by weight of the composition for forming a photostable wavelength conversion material.

[0097] A chromophore, sometimes referred to as a luminescent or fluorescent dye, is a compound that absorbs photons of a particular wavelength or wavelength range, and re-emits the photon at a different wavelength. In some embodiments, chromophores may be employed in solar cells convert radiation to useable wavelengths. Since solar cells and photovoltaic devices are often exposed to extreme environmental conditions for long periods of time (i.e. 20+ years, 10+ years, 5+ years) the stability of the chromophore is important. In some embodiments, the composition for forming a photostable wavelength conversion material comprises chromophores with good photostabilty for long periods of time (i.e. 20,000+ hours, 10,000+ hours, or 5,000+ hours) of illumination under one sun (AM1.5G) irradiation (with less than 10%, 5%, 3%, 2%, or 1 % degradation) are used in the wavelength conversion composition.

[0098] In some embodiments, the composition for forming a photostable wavelength conversion material comprises organic chromophores. In some embodiments, a first chromophore is used in the composition to form the wavelength conversion material. In some embodiments, in addition to the first chromophore, an independently selected second chromophore is used. In some embodiments, 1 , 2, 3, 4, 5, or more independently selected additional chromophores are used in combination with the first and second chromophores.

[0099] It may be desirable to have multiple chromophores in the wavelength conversion composition, depending on the solar energy conversion device that the material is to encapsulate. For example, the first chromophore may act to convert photons of wavelengths 300-400 nm to wavelengths of 500 nm, and the second chromophore may act to convert photons of wavelengths 400-475 nm to wavelengths of 500 nm (or vice versa), wherein the solar energy conversion device that is to be encapsulated by the composition exhibits optimum photoelectric conversion efficiency at 500 nm wavelengths, so that the encapsulation of the devices by the wavelength conversion composition significantly enhances the solar harvesting efficiency of the solar energy conversion device.

[0100] In some embodiments, the first chromophore is an up-conversion dye, meaning a chromophore that converts photons from lower energy (long wavelengths) to higher energy (short wavelengths). Up-conversion dyes may include rare earth materials which have been found to absorb photons of wavelengths in the IR region, ~975nm, and re- emit in the visible region (400-700nm), for example, Yb , Tm , Er , Ho , and NaYF . Additional up-conversion materials are described in U.S. Patent Nos. 6,654,161 , and 6,139,210, and in the Indian Journal of Pure and Applied Physics, volume 33, pages 169-178, (1995), which are hereby incorporated by reference in their entirety.

[0101] In some embodiments, the first chromophore is a down-shifting dye, meaning a chromophore that converts photons of high energy (short wavelengths) into lower energy (long wavelengths).

[0102] In some embodiments, the first chromophore is an organic compound. In some embodiments, the first chromophore is selected from perylene derivative dyes, benzotriazole derivative dyes, or benzothiadiazole derivative dyes. Examples of chromophores can be found in U.S. Application Publication US2013/0074927, which is hereby incorporated by reference in its entirety.

[0103] In some embodiments, the first chromophore comprises a structure as given by the following general formula (I):

wherein Ri , R₂, and R₃ comprise and alkyl, a substituted alkyl, or an aryl. Example

[0104] The term "alkyl" refers to a branched or straight fully saturated acyclic aliphatic hydrocarbon group (i.e. composed of carbon and hydrogen containing no double or triple bonds). Alkyls include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, pentyl, hexyl, and the like.

[0105] The term "heteroalkyl" used herein refers to an alkyl group comprising one or more heteroatoms. When two or more heteroatoms are present, they may be the same or different.

[0106] The term "cycloalkyl" used herein refers to saturated aliphatic ring system radical having three to twenty-five carbon atoms including, but not limited to, cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, and the like. [0107] The term "polycycloalkyl" used herein refers to saturated aliphatic ring system radical having multiple cylcoalkyl ring systems.

[0108] The term "alkenyl" used herein refers to a monovalent straight or branched chain radical of from two to twenty-five carbon atoms containing at least one carbon double bond including, but not limited to, 1-propenyl, 2-propenyl, 2-methyl-l- propenyl, 1 -butenyl, 2-butenyl, and the like.

[0109] The term "alkynyl" used herein refers to a monovalent straight or branched chain radical of from two to twenty-five carbon atoms containing a carbon triple bond including, but not limited to, 1-propynyl, 1-butynyl, 2-butynyl, and the like.

[0110] The term "aryl" used herein refers to homocyclic aromatic radical whether one ring or multiple fused rings. Examples of aryl groups include, but are not limited to, phenyl, naphthyl, phenanthrenyl, naphthacenyl, fluorenyl, pyrenyl, and the like. Further examples include:

naphthalen-1 -yl naphthalen-2-yl anthracen-1-yl anthracen-2-yl anthracen-9-yl

pyren-1-yl perylen-3-yl 9H-fluoren-2-yl

[0111] The term "alkaryl" or "alkylaryl" used herein refers to an alkyl-substituted aryl radical. Examples of alkaryl include, but are not limited to, ethylphenyl, 9,9-dihexyl- 9H-fluorene, and the like. [0112] The term "aralkyl" or "arylalkyl" used herein refers to an aryl-substituted alkyl radical. Examples of aralkyl include, but are not limited to, phenylpropyl, phenylethyl, and the like.

[0113] The term "heteroaryl" used herein refers to an aromatic group comprising one or more heteroatoms, whether one ring or multiple fused rings. When two or more heteroatoms are present, they may be the same or different. In fused ring systems, the one or more heteroatoms may be present in only one of the rings. Examples of heteroaryl groups include, but are not limited to, benzothiazyl, benzoxazyl, quinazolinyl, quinolinyl, isoquinolinyl, quinoxalinyl, pyridinyl, pyrrolyl, oxazolyl, indolyl, thiazyl and the like. Further exam les of substituted and unsubstituted heteroaryl rings include:

uinolin-2-yl quinolin-4-yl quinolin-6-yl isocM"⁰¹^-¹^¹ quinazolin-2-yl

quinazolin-4-yl phthalazin-1 -yl quinoxalin-2-yl naphthyridin-4-yl 9H-purin-6-yl 1

furan-2-yl thiophen-2-yl

indol-2-yl indol-3-yl

-3-yl

benzofuran-2-yl benzothiophen-2-yl 9H-carbazol-2yl dibenzofuran-4-yl dibenzothiophen-4-yl

[0114] The term "alkoxy" used herein refers to straight or branched chain alkyl radical covalently bonded to the parent molecule through an— 0-- linkage. Examples of alkoxy groups include, but are not limited to, methoxy, ethoxy, propoxy, isopropoxy, butoxy, n-butoxy, sec-butoxy, t-butoxy and the like.

[0115] The term "heteroatom" used herein refers to any atom that is not C (carbon) or H (hydrogen). Examples of heteroatoms include S (sulfur), N (nitrogen), and O (oxygen).

[0116] The term "cyclic amino" used herein refers to either secondary or tertiary amines in a cyclic moiety. Examples of cyclic amino groups include, but are not limited to, aziridinyl, piperidinyl, N-methylpiperidinyl, and the like.

[0117] The term "cyclic imido" used herein refers to an imide in the radical of which the two carbonyl carbons are connected by a carbon chain. Examples of cyclic imide groups include, but are not limited to, 1 ,8-naphthalimide, pyrrolidine-2,5-dione, lH-pyrrole- 2,5-dione, and the likes.

[0118] The term "alcohol" used herein refers to a radical -OH.

[0119] The term "acyl" used herein refers to a radical -C(=0)R.

[0120] The term "aryloxy" used herein refers to an aryl radical covalently bonded to the parent molecule through an— 0-- linkage.

[0121] The term "acyloxy" used herein refers to a radical -0-C(=0)R.

[0122] The term "carbamoyl" used herein refers to a radical -C(=0)NH₂.

[0123] The term "carbonyl" used herein refers to a functional group C=0.

[0124] The term "carboxy" used herein refers to a radical -COOR. [0125] The term "ester" used herein refers to a functional group RC(=0)OR'.

[0126] The term "amido" used herein refers to a radical -C(=0)NR'R".

[0127] The term "amino" used herein refers to a radical -NR'R".

[0128] The term "heteroamino" used herein refers to a radical -NR'R" wherein R' and/or R" comprises a heteroatom.

[0129] The term "heterocyclic amino" used herein refers to either secondary or tertiary amines in a cyclic moiety wherein the group further comprises a heteroatom.

[0130] The term "cycloamido" used herein refers to an amido radical of- C(=0)NR'R" wherein R' and R" are connected by a carbon chain.

[0131] The term "sulfone" used herein refers to a sulfonyl radical of -S(=0)₂R.

[0132] The term "sulfonamide" used herein refers to a sulfonyl group connected to an amine group, the radical of which is -S(=0)₂-NR'R".

[0133] As used herein, a substituted group is derived from the unsubstituted parent structure in which there has been an exchange of one or more hydrogen atoms for another atom or group. When substituted, the substituent group(s) is (are) one or more group(s) individually and independently selected from C₁-C25 alkyl, C2-C25 alkenyl, C2-C25 alkynyl, C₃-C25 cycloalkyl (optionally substituted with a moiety selected from the group consisting of halo, alkyl, alkoxy, alcohol, carboxyl, haloalkyl, CN, OH, -S0₂-alkyl, -CF₃, and -OCF₃), cycloalkyl geminally attached, C₁-C25 heteroalkyl, C₃-C25 heterocycloalkyl (e.g., tetrahydrofuryl) (optionally substituted with a moiety selected from the group consisting of halo, alkyl, alkoxy, alcohol, carboxyl, CN, -S0₂-alkyl, -CF₃, and -OCF₃), aryl (optionally substituted with a moiety selected from the group consisting of halo, alkyl, arylalkyl, alkoxy, alcohol, aryloxy, carboxyl, amino, imido, amido (carbamoyl), optionally substituted cyclic imido, cylic amido, CN, -NH-C(=0)-alkyl, -CF₃ -OCF₃, and aryl optionally substituted with C₁-C25 alkyl), arylalkyl (optionally substituted with a moiety selected from the group consisting of halo, alkyl, alkoxy, alcohol, aryl, carboxyl, CN, -S0₂- alkyl, -CF₃, and -OCF₃), heteroaryl (optionally substituted with a moiety selected from the group consisting of halo, alkyl, alkoxy, alcohol, aryl, heteroaryl, aralkyl, carboxyl, CN, - S0₂-alkyl, -CF₃, and -OCF₃), halo (e.g., chloro, bromo, iodo and fluoro), cyano, hydroxy, optionally substituted cyclic imido, amino, imido, amido, -CF₃, C₁-C25 alkoxy (optionally substituted with halo, alkyl, alkoxy, aryl, carboxyl, CN, OH, -S0₂-alkyl, -CF₃, and -OCF₃), aryloxy, acyloxy, sulfhydryl (mercapto), halo(Ci-C₆)alkyl, Ci-C₆ alkylthio, arylthio, mono- and di-(Ci-C₆)alkyl amino, quaternary ammonium salts, amino(Ci-Ce)alkoxy, hydroxy(Ci- Ce)alkylamino, amino(Ci-C₆)alkylthio, cyanoamino, nitro, carbamoyl, keto (oxy), carbonyl, carboxy, acyl, glycolyl, glycyl, hydrazino, guanyl, sulfamyl, sulfonyl, sulfinyl, thiocarbonyl, thiocarboxy, sulfonamide, ester, C-amide, N-amide, N-carbamate, O-carbamate, urea and combinations thereof. Wherever a substituent is described as "optionally substituted" that substituent can be substituted with the above substituents.

[0134] In some embodiments, the first chromophore comprises a structure as given by the following formula (Il-a) or (Il-b):

substituted alkenyl, optionally substituted cycloalkyl, optionally substituted heteroalkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted alkoxyalkyl, optionally substituted heteroalkenyl, optionally substituted arylalkyl, optionally substituted heteroaryl, optionally substituted cycloalkenyl, optionally substituted cyclohetero alkyl, optionally substituted cycloheteroalkenyl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, and optionally substituted carboxy, optionally substituted carbonyl, optionally substituted ether, optionally substituted ketone, optionally substituted sulfone, and optionally substituted sulfonamide; or R³ is an optionally substituted polycyclic ring system, wherein each ring is independently cycloalkyl, aryl, heterocycloalkyl, or heteroaryl; R⁴, R⁵, and R⁶ are independently selected from the group consisting of optionally substituted alkyl, optionally substituted alkenyl, optionally substituted cycloalkyl, optionally substituted heteroalkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted alkoxyalkyl, optionally substituted heteroalkenyl, optionally substituted arylalkyl, optionally substituted heteroaryl, optionally substituted heteroarylalkyl, optionally substituted cycloalkenyl, optionally substituted cycloheteroalkyl, optionally substituted cycloheteroalkenyl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, and optionally substituted carboxy, and optionally substituted carbonyl, optionally substituted ether, optionally substituted ketone, optionally substituted sulfone, and optionally substituted sulfonamide; or R⁴ and R⁵, R⁴ and R⁶, R⁵ and R⁶, or R⁴ and R⁵ and R⁶, together form an optionally substituted ring or an optionally substituted polycyclic ring system, wherein each ring is independently cycloalkyl, aryl, heterocyclalkyl, or heteroaryl; and L is selected from the group consisting of optionally substituted alkyl, optionally substituted heteroalkyl, optionally substituted alkylene, and optionally substituted heteroalkylene, optionally substituted alkynylene, optionally substituted arylene, optionally substituted heteroarylene.

[0135] In some embodiments, R in formula Il-a and formula Il-b is selected from the group consisting of C_1-25 alkyl, C_1-25 heteroalkyl, C₂-25 alkenyl, C3-25 cycloalkyl, polycycloalkyl, heterocycloalkyl, arylalkyl; and R³ may be optionally substituted with one or more of any of the following substituents: C_1-25 alkyl, C_1-25 heteroalkyl, C₂-25 alkenyl, C3-25 cycloalkyl, polycycloalkyl, heterocycloalkyl, aryl, heteroaryl, OH, C_mH_2m+iO ether, C_mH_2m+iCO ketone, C_mH_2m+iC0₂ carboxylic ester, C_mH_2m+iOCO carboxylic ester, ArO aryloxy, ArCO aryl ketone, ArC0₂ ester of aryl-carboxylic acid, ArOCO carboxylic ester of phenol, (C_mH_2m+i)(C_pH_2p+i)N amine, c-(CH₂)_sN amine, (C_mH_2m+i)(C_pH_2p+i)NCO amide, c- (CH₂)sNCO amide, C_mH_2m+iCON(CpH₂p₊i) amide, CN, C_mH_2m+iS0₂ sulfone, (C_mH2m₊i)(CpH2_P+i) S02 sulfonamide, C_mH2_m+iS02 (C_pH2p₊i) sulfonamide, or c- (CH₂)_S S0₂ sulfonamide, wherein m is an integer in the range of 1 to 20, p is an integer in the range of 1 to 20, s is an integer in the range of 2 to 6, and Ar is any aromatic or heteroaromatic ring. R⁴, R⁵, and R⁶ in formula Il-a and formula Il-b are independently selected from the group consisting of C_1-25 alkyl, C_1-25 heteroalkyl, C₂-25 alkenyl, C3-25 cycloalkyl, polycycloalkyl, heterocycloalkyl, aryl, heteroaryl, arylalkyl, heteroarylalkyl, C0₂C_mH_2m+i carboxylic ester, (C_mH_2m+i)(C_pH_2P+i)NCO amide, c-(CH₂)_sNCO amide, COC_mH_2m+i ketone, COAr, S0₂C_mH_2m+i sulfone, S0₂Ar sulfone, (C_mH_2m+i)(CpH₂p₊i)S02 sulfonamide, c-(CH₂)_sS0₂ sulfonamide; and R⁴, R⁵, and R⁶ are independently optionally substituted with one or more of any of the following substituents: C_1-25 alkyl, C_1-25 heteroalkyl, C₂-25 alkenyl, C3-25 cycloalkyl, polycycloalkyl, heterocycloalkyl, aryl, heteroaryl, OH, C_mH_2m+iO ether, C_mH_2m+iCO ketone, C_mH_2m+iC0₂ carboxylic ester, C_mH_2m+iOCO carboxylic ester, ArO aryloxy, ArCO aryl ketone, ArC0₂ ester of aryl carboxylic acid, ArOCO carboxylic ester of phenol, (C_mH_2m+i)(C_pH_2P+i)N amine, c-(CH₂)_s amine, (C_mH_2m+i)(C_pH_2p+i)NCO amide, c-(CH₂)_sNCO amide, C_mH_2m+iCON(C_pH_2p+i) amide, C_mH_2m+iS0₂ sulfone, (C_mH_2m+i)(CpH₂p₊i)NS02 sulfonamide, C_mH_2m+iS02N(CpH₂p₊i) sulfonamide, or c-(CH₂)_sNS0₂ sulfonamide, wherein m is an integer in the range of 1 to 20, p is an integer in the range of 1 to 20, s is an integer in the range of 2 to 6, and Ar is any aromatic or heteroaromatic ring. L in formula Il-b is selected from the group consisting of Ci-25 alkyl, C_1-25 heteroalkyl, C₂-25 alkenyl; and L may be optionally substituted with one or more of any of the following substituents: C_1-25 alkyl, C_1-25 heteroalkyl, C₂-25 alkenyl, C3-25 cycloalkyl, polycycloalkyl, heterocycloalkyl, aryl, heteroaryl, OH, C_mH2_m+iO ether, C_mH2m₊iCO ketone, C_mH2_m+iC0₂ carboxylic ester, C_mH2_m+iOCO carboxylic ester, ArO aryloxy, ArCO aryl ketone, ArC0₂ ester of aryl-carboxylic acid, ArOCO carboxylic ester of phenol, (C_mH2_m+i)(C_pH2p₊i) amine, c-(CH₂)_sN amine, (C_mH2_m+i)(C_pH2p₊i)NCO amide, c- (CH₂)sNCO amide, C_mH_2m+iCON(CpH₂p₊i) amide, CN, C_mH_2m+iS0₂ sulfone, (C_mH_2m+i)(C_pH_2p+i)NS0₂ sulfonamide, C_mH_2m+iS0₂ (C_pH_2p+i) sulfonamide, or c- (CH₂)_S S0₂ sulfonamide, wherein m is an integer in the range of 1 to 20, p is an integer in the range of 1 to 20, s is an integer in the range of 2 to 6, and Ar is any aromatic or heteroaromatic ring.

[0136] In some embodiments, R in formula Il-a and formula Il-b is selected from the group consisting of C_1-25 alkyl, C_1-25 heteroalkyl, C₂-25 alkenyl, C3-25 cycloalkyl, C5-25 polycycloalkyl, C_1-25 heterocycloalkyl, C_1-25 arylalkyl; R⁴, R⁵, and R⁶ are independently optionally substituted with one or more of any of the following substituents: C_1-25 alkyl, C_1-25 heteroalkyl, C₂-25 alkenyl, C3-25 cycloalkyl, C_1-25 aryl, and C_1-25 heteroaryl.

[0137] In some embodiments the first chromo hore is selected from the rou

consisting of:

-29-

wherein D¹ and D² are electron donating groups, L¹ is an electron donor linker, and A⁰ and A¹ are electron acceptor groups. In some embodiments, where more than one electron donor group is present, the other electron donor groups may be occupied by another electron donor, a hydrogen atom, or another neutral substituent. In some embodiments, at least one of the D¹, D², and L' is a group which increases the electron density of the 2H- benzo[JJ[l ,2,3]triazole system to which it is attached.

[0139] In formulae Ill-a and III-b, i is an integer in the range of 0 to 100. In some embodiments, i is an integer in the range of 0 to 50, 0 to 30, 0 to 10, 0 to 5, or 0 to 3. In some embodiments, i is 0, 1 , 2, 3, 4, 5, 6, 7, 8, 9, or 10. [0140] In formulae Ill-a and Ill-b, A⁰ and A¹ are each independently selected from the group consisting of optionally substituted alkyl, optionally substituted alkenyl, optionally substituted heteroalkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, and optionally substituted carboxy, and optionally substituted carbonyl.

[0141] In some embodiments, A⁰ and A¹ are each independently selected from the group consisting of optionally substituted heteroaryl, optionally substituted aryl, optionally substituted cyclic imido, optionally substituted C_1-8 alkyl, and optionally substituted C_1-8 alkenyl; wherein the substituent for optionally substituted heteroaryl is selected from the group consisting of alkyl, aryl and halogen; the substitutent for optionally substituted aryl is -NR⁷-C(=0)R⁸ or optionally substituted cyclic imido, wherein wherein R⁷ is selected from the group consisting of H, alkyl, alkenyl, aryl, heteroaryl, aralkyl, alkaryl; and R⁸ is selected from the group consisting of optionally substituted alkylene, optionally substituted alkenylene, optionally substituted arylene, optionally substituted heteroarylene, ketone, and

7 8

ester; or R and R may be connected together to form a ring.

[0142] In some embodiments, A⁰ and A¹ are each independently phenyl

7 8 substituted with a moiety selected from the group consisting of -NR -C(=0)R and

7 8

optionally substituted cyclic imido, wherein R and R are as described above.

[0143] In some embodiments, A⁰ and A¹ are each optionally substituted heteroaryl or optionally substituted cyclic imido; wherein the substituent for optionally substituted heteroaryl and optionally substituted cyclic imido is selected from the group consisting of alkyl, aryl and halogen. In some embodiments, at least one of the A and A¹ is selected from the group consisting of: optionally substituted pyridinyl, optionally substituted pyridazinyl, optionally substituted pyrimidinyl, optionally substituted pyrazinyl, optionally substituted triazinyl, optionally substituted quinolinyl, optionally substituted isoquinolinyl, optionally substituted quinazolinyl, optionally substituted phthalazinyl, optionally substituted quinoxalinyl, optionally substituted naphthyridinyl, and optionally substituted purinyl.

[0144] In other embodiments, A⁰ and A¹ are each optionally substituted alkyl. In other embodiments, A⁰ and A¹ are each optionally substituted alkenyl. In some embodiments, at least one of the A⁰ and A¹ is selected from the group consisting of:

_; wherein R is optionally substituted alkyl.

[0145] In formula Ill-a and Ill-b, A² is selected from the group consisting of optionally substituted alkylene, optionally substituted alkenylene, optionally substituted

arylene, optionally substituted heteroarylene, ketone, ester, and

wherein Ar is optionally substituted aryl or optionally substituted heteroaryl. R⁷ is selected from the group consisting of H, alkyl, alkenyl, aryl, heteroaryl, aralkyl, alkaryl; and R⁸ is selected from the group consisting of optionally substituted alkylene, optionally substituted alkenylene, optionally substituted arylene, optionally substituted heteroarylene, ketone, and ester; or R⁷ and R⁸ may be connected together to form a ring.

[0146] In some embodiments, A² is selected from the group consisting of optionally substituted arylene, optionally substituted heteroarylene, and

wherein Ar, R⁷ and R⁸ are as described above.

[0147] In formulae Ill-a and Ill-b, D¹ and D² are each independently selected from the group consisting of hydrogen, optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted acyloxy, optionally substituted alkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted amino, amido, cyclic amido,

1 2

and cyclic imido, provided that D and D are not both hydrogen.

[0148] In some embodiments, D¹ and D² are each independently selected from the group consisting of hydrogen, optionally substituted aryl, optionally substituted heteroaryl,

1 2 1 2 and amino, provided that D and D are not both hydrogen. In some embodiments, D and D are each independently selected from the group consisting of hydrogen, optionally substituted aryl, optionally substituted heteroaryl, and diphenylamino, provided that D¹ and D² are not both hydrogen. 1 2 ·

[0149] In some embodiments, D and D are each independently optionally

1 2 ·

substituted aryl. In some embodiments, D and D are each independently phenyl optionally

1 2

substituted by alkoxy or amino. In other embodiments, D and D are each independently selected from hydrogen, optionally substituted benzofuranyl, optionally substituted thiophenyl, optionally substituted furanyl, dihydrothienodioxinyl, optionally substituted benzothiophenyl, and optionally substituted dibenzothiophenyl, provided that D¹ and D² are not both hydrogen.

[0150] In some embodiments, the substituent for optionally substituted aryl and soptionally substituted heteroaryl may be selected from the group consisting of alkoxy, aryloxy, aryl, heteroaryl, and amino.

[0151] In formulae Ill-a and Ill-b, L¹ is independently selected from the group consisting of optionally substituted alkylene, optionally substituted alkenylene, optionally substituted alkynylene, optionally substituted arylene, optionally substituted heteroarylene. In some embodiments, L¹ is selected from the group consisting of optionally substituted heteroarylene and optionally substituted arylene.

[0152] In some embodiments, at least one of the L¹ is selected from the group consisting of: 1 ,2-ethylene, acetylene, 1 ,4-phenylene, l ,l '-biphenyl-4,4'-diyl, naphthalene -

2.6- diyl, naphthalene- 1 ,4-diyl, 9H-fluorene-2,7-diyl, perylene-3,9-diyl, perylene-3,10-diyl, or pyrene-l ,6-diyl, lH-pyrrole-2,5-diyl, furan-2,5-diyl, thiophen-2,5-diyl, thieno[3,2- ¾]thiophene-2,5-diyl, benzo[c]thiophene-l ,3-diyl, dibenzo[¾,J]thiophene-2,8-diyl, 9H- carbozole-3,6-diyl, 9H-carbozole-2,7-diyl, dibenzo[¾,JJfuran-2,8-diyl, lOH-phenothiazine-

3.7- diyl, and 10H-phenothiazine-2,8-diyl; wherein each moiety is optionally substituted. Formulae IV-a and IV-b

[0153] In some embodiments, the first chromophore comprises a structure as given by formula (IV-a) or (IV-b):

wherein i is an integer in the range of 0 to 100. In some embodiments, i is an integer in the range of 0 to 50, 0 to 30, 0 to 10, 0 to 5, or 0 to 3. In some embodiments, i is 0, 1 , 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0154] In formulae IV-a and IV-b, Ar is optionally substituted aryl or optionally substituted heteroaryl. In some embodiments, aryl substituted with an amido or a cyclic imido group at the N-2 position of the 2H-benzo[J][l ,2,3]triazole ring system provides unexpected and improved benefits.

[0155] In formulae IV-a and IV-b, R⁹ is

or optionally substituted cyclic imido; R⁷ is each indepedently selected from the group consisting of Η, alkyl, alkenyl, aryl, heteroaryl, aralkyl, alkaryl; R¹⁰ is each independently selected from the group consisting of optionally substituted alkyl, optionally substituted alkenyl, optionally

7 10

substituted aryl, optionally substituted heteroaryl; or R and R may be connected together to form a ring.

[0156] In some embodiments, R⁹ is optionally substituted cyclic imido selected from the group consisting of:

each optionally substituted alkyl or optionally substituted aryl; and X is optionally substituted heteroalkyl.

[0157] In formulae IV-a and IV-b, R is selected from the group consisting of optionally substituted alkylene, optionally substituted alkenylene, optionally substituted arylene, optionally substituted heteroarylene.

1 2

[0158] In formulae IV-a and IV-b, D and D are each independently selected from the group consisting of hydrogen, optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted acyloxy, optionally substituted alkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted amino, amido, cyclic amido, and cyclic imido, provided that D¹ and D² are not both hydrogen.

[0159] In formulae IV-a and IV-b, L¹ is independently selected from the group consisting of optionally substituted alkylene, optionally substituted alkenylene, optionally substituted alkynylene, optionally substituted arylene, optionally substituted heteroarylene.

[0160] In some embodiments, at least one of the L¹ is selected from the group consisting of: 1 ,2-ethylene, acetylene, 1 ,4-phenylene, l ,l '-biphenyl-4,4'-diyl, naphthalene -

3.7- diyl, and 10H-phenothiazine-2,8-diyl; wherein each moiety is optionally substituted. Formulae V-a and V-b

[0161] In some embodiments, the first chromophore comprises a structure as given by formula (V-a) or (V-b):

(V-b);

The placement of an alkyl group in formulae (V-a) and (V-b) at the N-2 position of the 2H- benzo[JJ[ l ,2,3]triazole ring system along with substituted phenyls at the C-4 and C-7 positions provides unexpected and improved benefits. In formula V-a and V-b, i is an integer in the range of 0 to 100. In some embodiments, i is an integer in the range of 0 to 50, 0 to 30, 0 to 10, 0 to 5, or 0 to 3. In some embodiments, i is 0, 1 , 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0162] In formula V-a and V-b, A⁰ and A¹ are each independently selected from the group consisting of optionally substituted alkyl, optionally substituted alkenyl, optionally substituted heteroalkyl, optionally substituted amido, optionally substituted alkoxy, optionally substituted cabonyl, and optionally substituted carboxy.

[0163] In some embodiments, A⁰ and A¹ are each independently unsubstituted alkyl or alkyl substituted by a moiety selected from the group consisting of: -NRR", -OR, - COOR, -COR, -CONHR, -CONRR", halo and -CN; wherein R is Ci-C₂₀ alkyl, and R" is hydrogen or Ci-C₂o alkyl. In some embodiments, the optionally substituted alkyl may be optionally substituted C1-C40 alkyl. In some embodiments, A⁰ and the A¹ are each independently C1-C40 alkyl or Ci-C₂o haloalkyl.

[0164] In some embodiments, A⁰ and A¹ are each independently Ci-C₂o haloalkyl, C1-C40 arylalkyl, or Ci-C₂o alkenyl.

[0165] In formulae V-a and V-b, each R¹¹ is independently selected from the group consisting of optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted acyloxy, and amino. In some embodiments, each R¹¹ is independently selected from the group consisting of optionally substituted Ci-C₂o alkoxy, optionally substituted d- C₂o aryloxy, optionally substituted Ci-C₂o acyloxy, and Ci-C₂o amino. In some embodiments, R¹¹ may attach to phenyl ring at ortho and/or para position. In some embodiments, R¹¹ may be alkoxy represented by the formula OC_nH_2n+i where n = 1-40. In some embodiments, R¹¹ may be aryloxy represented by the following formulae: ArO or O- CR-OAr where R is alkyl, substituted alkyl, aryl, or heteroaryl, and Ar is any substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl. In some embodiments, R¹¹ may be acyloxy represented by the formula OCOC_nH_2n+i where n = 1-40.

[0166] In formulae V-a and V-b, A is selected from the group consisting of optionally substituted alkylene, optionally substituted alkenylene, optionally substituted

arylene, optionally substituted heteroarylene, ketone, ester, and

; wherein Ar is optionally substituted aryl or optionally substituted heteroaryl, R⁷ is selected from the group consisting of H, alkyl, alkenyl, aryl, heteroaryl, aralkyl, and alkaryl; and R⁸ is selected from the group consisting of optionally substituted alkylene, optionally substituted alkenylene, optionally substituted arylene, optionally substituted heteroarylene, ketone, and ester; or R⁷ and R⁸ may be connected together to form a ring. In some embodiments, R⁷ is selected from the group consisting of H, C1-C20 alkyl, C1-C20 alkenyl, C1-C20 aryl, C1-C20 heteroaryl, C₁-C₂₀ aralkyl, and C₁-C₂₀ alkaryl; and R⁸ is selected from the group consisting of optionally substituted C₁-C₂₀ alkylene, optionally substituted C₁-C₂₀ alkenylene, optionally substituted C₁-C₂₀ arylene, optionally substituted C₁-C₂₀ heteroarylene, ketone, and ester

[0167] In formulae V-a and V-b, L¹ is independently selected from the group consisting of optionally substituted alkylene, optionally substituted alkenylene, optionally substituted alkynylene, optionally substituted arylene, optionally substituted heteroarylene.

[0168] In some embodiments, at least one of the L¹ is selected from the group consisting of: 1 ,2-ethylene, acetylene, 1 ,4-phenylene, l ,l '-biphenyl-4,4'-diyl, naphthalene -

3.7- diyl, and 10H-phenothiazine-2,8-diyl; wherein each moiety is optionally substituted. Formula VI

[0169] In some embodiments, the first chromophore comprises a structure as given by formulae

[0170] In formula VI, Z and Z_\ are each independently selected from the group consisting of -0-, -S-, -Se- -Te- -NR⁶-, -CR⁶=CR⁶-, and -CR⁶=N- wherein R⁶ is hydrogen, optionally substitute Ci-C₆ alkyl, or optionally substituted C₁-C₁₀ aryl; and

[0171] In formula VI, D¹ and D² are independently selected from the group consisting of optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted acyloxy, optionally substituted alkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted amino, amido, cyclic amido, and cyclic imido; j is 0, 1 or 2, and k is 0, 1 , or 2. In some embodiments, the -C(=0)Yi and -C(=0)Y₂ groups may attach to the substituent(s) of the optionally substituted moiety for D¹ and D².

[0172] In formula VI, Yi and Y₂ are independently selected from the group consisting of optionally substituted aryl, optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted alkoxy, and optionally substituted amino; and

[0173] In formula VI, L¹ is independently selected from the group consisting of optionally substituted alkylene, optionally substituted alkenylene, optionally substituted alkynylene, optionally substituted arylene, optionally substituted heteroarylene.

[0174] In some embodiments, at least one of the L¹ is selected from the group consisting of: 1 ,2-ethylene, acetylene, 1 ,4-phenylene, l ,l '-biphenyl-4,4'-diyl, naphthalene -

3.7- diyl, and 10H-phenothiazine-2,8-diyl; wherein each moiety is optionally substituted.

[0175] With regard to L¹ in any of the formulae above, the electron linker represents a conjugated electron system, which may be neutral or serve as an electron donor itself. In some embodiments, some examples are provided below, which may or may not contain additional attached substituents.

naphthalene-1 ,4-diyl 9/-/-fluorene-2,7-diyl

pyrene-1 ,6-diyl

perylene-3,9-diyl perylene-3,10-diyl etc.

furan-2,5-diyl thiophen-2,5-diyl

pyrrole-2,5-diyl

thieno[3,2-f)]thiophene-2,5-diyl benzo[c]thiophene-1 ,3-diyl dibenzo[b,d]thiophene-2,8

9H-carbazole-3,6-diyl dibenzo[ft,cf]furan-2,8-diyl 10H-phenothiazine-3,7- etc.

Formulae Vll-a and VII -b

[0176] In some embodiments, the first chromophore comprises a structure by formula (Vll-a) or (Vll-b):

wherein R and R in formula (Vll-a) are each independently selected from the group consisting of hydrogen, Ci-Cio alkyl, C3-C10 cycloalkyl, C1-C10 alkoxy, C₆-Ci8 aryl, and C₆- C20 aralkyl; m and n in formula (Vll-a) are each independently in the range of from 1 to 5; and R¹⁵ and R¹⁶ in formula (Vll-b) are each independently selected from the group consisting of a C₆-Ci8 aryl and C6-C20 aralkyl. In some embodiments, if one of the cyano groups on formula (Vll-b) is present on the 4-position of the perylene ring, then the other cyano group is not present on the 10-position of the perylene ring. In some embodiments, if one of the cyano groups on formula (Vll-b) is present on the 10-position of the perylene ring, then the other cyano group is not present on the 4-position of the perylene ring.

[0177] In some embodiments, R¹³ and R¹⁴ are independently selected from the group consisting of hydrogen, Ci-C₆ alkyl, C2-C6 alkoxyalkyl, and C₆-Ci8 aryl. In some embodiments, R¹³ and R¹⁴ are each independently selected from the group consisting of isopropyl, isobutyl, isohexyl, isooctyl, 2-ethyl-hexyl, diphenylmethyl, trityl, and diphenyl. In some embodiments, R¹⁵ and R¹⁶ are independently selected from the group consisting of diphenylmethyl, trityl, and diphenyl. In some embodiments, each m and n in formula (Vll-a) is independently in the range of from 1 to 4.

[0178] The perylene diester derivative represented by the general formula (Vll-a) or general formula (Vll-b) can be made by known methods, such as those described in International Publication No. WO 2012/094409, the contents of which are hereby incorporated by reference in their entirety.

Formulae VIII

[0179] In some embodiments, the first chromophore comprises a structure as given by formula (VIII):

D-,— Het-(-L-Het -D₂

' (VIII)

wherein Het is selected from the group consisting of:

and wherein i is 0 or an integer in the range of 1 to 100, X is selected from the group consisting of -N(Ao)-, -0-, -S-, -Se-, and -Te-, and Z is selected from the group consisting of-N(R_a)-, -0-, -S-, -Se- and -Te-.

[0180] Each Ao in formula VIII is selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted heteroalkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, optionally substituted acyl, optionally substituted carboxy, and optionally substituted carbonyl.

[0181] Each R_a, and R_c, of formula VIII are independently selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkoxyalkyl, optionally substituted alkenyl, optionally substituted heteroalkyl, optionally substituted heteroalkenyl, optionally substituted aryl, optionally substituted arylalkyl, optionally substituted heteroaryl, optionally substituted cylcoalkyl, optionally substituted cycloalkenyl, optionally substituted cycloheteroalkyl, optionally substituted cycloheteroalkenyl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, optionally substituted carboxy, and optionally substituted carbonyl; or R_a and R_b, or R_b and R_c, or R_a and R_c, together form an optionally substituted ring or an optionally substituted polycyclic ring system, wherein each ring is independently cycloalkyl, aryl, heterocyclyl, or heteroaryl.

[0182] In some embodiments, each R_a, and R_c, of formula VIII are independently selected from the group consisting of hydrogen, optionally substituted C_1-8 alkyl, optionally substituted C₆-io aryl, and optionally substituted C₆-io heteroaryl. In some embodiments, each R_a, R_b, and R_c, of formula VIII are independently selected from the group consisting of hydrogen, C_1-8 alkyl, C₆-io aryl, and C₆-io heteroaryl, wherein C_1-8 alkyl, C₆-io aryl, and C₆-io heteroaryl may each be optionally substituted by optionally substituted C3-10 cycloalkyl, optionally substituted C_1-8 alkoxy, halo, cyano, carboxyl, optionally substituted

C₆-io aryl, optionally substituted C₆-io aryloxy,

In some embodiments, R_a and R_b, or R_b and R_c, or R_a and R_c, together form an optionally substituted

ring system selected from the group consisting of:

and

[0183] Di and D₂ are independently selected from the group consisting of hydrogen, optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted acyloxy, optionally substituted alkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted amino, amido, cyclic amido, and cyclic imido, - aryl-NR'R", -aryl-aryl-NR'R", and -heteroaryl-heteroaryl-R'; wherein R' and R" are independently selected from the group consisting of optionally substituted alkyl, optionally substituted alkenyl, optionally substituted aryl; provided that Di and D₂ are not both hydrogen, and Di and D₂ are not optionally substituted thiophene or optionally substituted furan.

[0184] In some embodiments, the chromophore is represented by formula VIII, wherein Di and D₂ are each independently selected from the group consisting of alkoxyaryl, -aryl-NR'R", and -aryl-aryl-NR'R"; wherein R' and R" are independently selected from the group consisting of alkyl and aryl optionally substituted by alkyl, alkoxy, or -C(=0)R; wherein R is optionally substituted aryl or optionally substituted alkyl; or one or both of R' and R" forms a fused heterocyclic ring with aryl to which the N is attached to.

[0185] In some embodiments, each Di and D₂ of formula VIII are independently C₆-io aryl or optionally substituted C₆-io aryl. The substituent(s) on the C₆-io aryl may be selected from the group consisting of -NR'R", -C₆-io aryl-NR'R", Ci_8 alkyl and Ci_8 alkoxy; wherein R' and R" are independently selected from the group consisting of Ci_8 alkyl, Ci_8 alkoxy, C₆-io aryl, C₆-io aryl-Ci-8 alkyl, C₆-io aryl-Ci-8 alkoxy, and C₆-io aryl-C(=0)R, wherein R is optionally substituted Ci_8 alkyl, optionally substituted Ci_8 alkoxy or optionally substituted C₆-io aryl; or one or both of R' and R" forms a fused heterocyclic ring with aryl to which the N is attached to.

[0186] L of formula VIII is independently selected from the group consisting of optionally substituted alkyl, optionally substituted aryl, optionally substituted heteroaryl, amino, amido, imido, optionally substituted alkoxy, acyl, carboxy, provided that L is not optionally substituted thiophene or optionally substituted furan.

[0187] In some embodiments, the chromophore is represented by formula VIII, wherein L is independently selected from the group consisting of haloalkyl, alkylaryl, alkyl substituted heteroaryl, arylalkyl, heteroamino, heterocyclic amino, cycloamido, cycloimido, aryloxy, acyloxy, alkylacyl, arylacyl, alkylcarboxy, arylcarboxy, optionally substituted phenyl, and optionally substituted naphthyl.

[0188] In some embodiments, the chromophore is represented by formula VIII, provided that when Het is:

, R_a and R_b are not both hydrogen, and Di and D₂ are independently selected

from the group consisting of:

[0189] In some embodiments, the chromophore is represented by formula VIII,

provided that when Het

, Ra and ¾, are not both hydrogen.

[0190] In some embodiments, the chromophore is represented by formula VIII,

wherein Het is

cted from the group consisting of -N(Ao)- and -Se-, Z

[0191] In some embodiments, the chromophore is represented by formula

VIII, wherein Het is: + , and X is selected from the group consisting of -S- and

-Se-, Z is -S-, and Di and D₂ are independently selected from the group consisting of:

[0192] In some embodiments, the chromophore is represented by formula VIII,

wherein Het is , and wherein Di and D₂ are not hydroxy, or / r o>— N— , and

Di and D₂ do not comprise bromine.

[0193] In formulae VIII, i is 0 or an integer in the range of 1 to 100. In some embodiments, i is 0 or an integer in the range of 1 to 50, 1 to 30, 1 to 10, 1 to 5, or 1 to 3. In some embodiments, i is 0, 1 , 2, 3, 4, 5, 6, 7, 8, 9, or 10.

Formulae IX-a and IX-b

[0194] In some embodiments, the first chromophore comprises a structure as given by formula (IX-a) or (IX-b):

Het₂-A₀-Het_{2 (Ix}._a)

(IX-b)

wherein Het₂ is selected from the group consisting of:

; and wherein Z is selected from the group consisting of -N(Ra)-,

S-, -Se-, and -Te-.

[0195] Each of the Ra, Rb, and Rc, in formula IX-a and formula IX-b is independently selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkoxyalkyl, optionally substituted alkenyl, optionally substituted heteroalkyl, optionally substituted heteroalkenyl, optionally substituted aryl, optionally substituted arylalkyl, optionally substituted heteroaryl, optionally substituted cylcoalkyl, optionally substituted cycloalkenyl, optionally substituted cycloheteroalkyl, optionally substituted cycloheteroalkenyl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, optionally substituted carboxy, and optionally substituted carbonyl; or R_a and Rb, or Rb and R_c, or Ra and R_c, together form an optionally substituted ring or an optionally substituted polycyclic ring system, wherein each ring is independently cycloalkyl, aryl, heterocyclyl, or heteroaryl.

[0196] In some embodiments, each R_a, R_b, and R_c is independently selected from the group consisting of hydrogen, optionally substituted C_1-8 alkyl, optionally substituted C_6- ₁₀ aryl, and optionally substituted C₆-io heteroaryl. In some embodiments, each R_a, R_b, and R_c, of formula (IX-a) and formula (IX-b) are independently selected from the group consisting of hydrogen, C_1-8 alkyl, C₆-io aryl, and C₆-io heteroaryl, wherein C_1-8 alkyl, C₆-io aryl, and C₆-io heteroaryl may each be optionally substituted by optionally substituted C3-₁₀ cycloalkyl, optionally substituted C_1-8 alkoxy, halo, cyano, carboxyl, optionally substituted

C₆-io aryl, optionally substituted C₆-io aryloxy,

ring system selected from the group consisting of:

and

[0197] Each of the R_d and R_e in formula IX-a and formula IX-b is independently selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkoxyalkyl, optionally substituted alkenyl, optionally substituted heteroalkyl, optionally substituted heteroalkenyl, optionally substituted aryl, optionally substituted arylalkyl, optionally substituted heteroaryl, optionally substituted cylcoalkyl, optionally substituted cycloalkenyl, optionally substituted cycloheteroalkyl, optionally substituted cycloheteroalkenyl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, optionally substituted carboxy, and optionally substituted carbonyl; or R_d and R_e together form an optionally substituted ring or an optionally substituted polycyclic ring system, wherein each ring is independently cycloalkyl, aryl, heterocyclyl, or heteroaryl. [0198] Each of Di, D₂, D₃, and D4 in formula IX-a and formula IX-b are each independently C₆-io aryl or optionally substituted C₆-io aryl. The substituent(s) on the C₆-io aryl may be selected from the group consisting of -NR'R", -C₆-io aryl-NR'R", Ci_8 alkyl and Ci-8 alkoxy, wherein R' and R" are independently selected from the group consisting of Ci_8 alkyl, Ci_8 alkoxy, C₆-io aryl, C₆-io aryl-Ci-8 alkyl, C₆-io aryl-Ci-8 alkoxy, and C₆-io aryl- C(=0)R, wherein R is optionally substituted Ci_8 alkyl, optionally substituted Ci_8 alkoxy or optionally substituted C₆-io aryl; or one or both of R' and R" forms a fused heterocyclic ring with aryl to which the N is attached to.

[0199] In some embodiments, the chromophore is represented by formula IX-a or IX-b, wherein Di and D₂ are each independently selected from the group consisting of alkoxyaryl, -aryl-NR'R", and -aryl-aryl-NR'R"; wherein R' and R" are independently selected from the group consisting of alkyl and aryl optionally substituted by alkyl, alkoxy, or -C(=0)R; wherein R is optionally substituted aryl or optionally substituted alkyl; or one or both of R' and R" forms a fused heterocyclic ring with aryl to which the N is attached to.

[0200] In some embodiments, each of Di, D₂, D₃, and D4 in formula IX-a and formula IX-b are each independently C₆-io aryl or optionally substituted C₆-io aryl. The substituent(s) on the C₆-io aryl may be selected from the group consisting of -NR'R", -C₆-io aryl-NR'R", Ci_8 alkyl and Ci_8 alkoxy, wherein R' and R" are independently selected from the group consisting of Ci_8 alkyl, Ci_8 alkoxy, C₆-io aryl, C₆-io aryl-Ci-8 alkyl, C₆-io aryl-Ci-8 alkoxy, and C₆-io aryl-C(=0)R, R is optionally substituted Ci_8 alkyl, optionally substituted Ci-8 alkoxy or optionally substituted C₆-io aryl; or one or both of R' and R" forms a fused heterocyclic ring with aryl to which the N is attached to.

[0201] In some represented by formula IX-a or

formula IX-b, wherein H

that R_a and R_b are not both hydrogen, and Di and D₂ are independently selected from the group consisting

[0202] In some embodiments, the chromophore is represented by formula IX-a or

formula IX-b, wherein Het₂ is

, provided that R_a and Rb are not both hydrogen.

[0203] In some emb is represented by formula IX-a or

formula IX-b, wherein Het₂

provided

independently selected from the group consisting

[0204] In some embodiments, the chromophore is represented by formula IX-a or

-b, wherein Het₂ is provided that Di and D₂ are not hydroxy, or

and Di and D₂ do not comprise bromine.

Formulae X-a and X-b

[0205] In some embodiments, the first chromophore comprises a structure as given by formula (X-a) or (X-b):

Het₃-R_a-Het₃ (_X._a)

(X-b)

wherein X is selected from the group consisting of -N(A₀)-, -0-, -S-, -Se-, and -Te-

[0206] Each Ao of formula X-a and formula X-b is selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted heteroalkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, optionally substituted acyl, optionally substituted carboxy, and optionally substituted carbonyl. In some embodiments, Ao is C_1-8 alkyl.

[0207] Each R_a, and R_c, of formula X-a and formula X-b is independently selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkoxyalkyl, optionally substituted alkenyl, optionally substituted heteroalkyl, optionally substituted heteroalkenyl, optionally substituted aryl, optionally substituted arylalkyl, optionally substituted heteroaryl, optionally substituted cylcoalkyl, optionally substituted cycloalkenyl, optionally substituted cycloheteroalkyl, optionally substituted cycloheteroalkenyl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, optionally substituted carboxy, and optionally substituted carbonyl; or R_a and R_b, or R_b and R_c, or R_a and R_c, together form an optionally substituted ring or an optionally substituted polycyclic ring system, wherein each ring is independently cycloalkyl, aryl, heterocyclyl, or heteroaryl.

[0208] In some embodiments, each Ra, and R_c is independently selected from the group consisting of hydrogen, optionally substituted C_1-8 alkyl, optionally substituted C_6- 10 aryl, and optionally substituted C₆-io heteroaryl. In some embodiments, each R_a, Rb, and Rc, of formula X-a and formula X-b are independently selected from the group consisting of hydrogen, C_1-8 alkyl, C₆-io aryl, and C₆-io heteroaryl, wherein C_1-8 alkyl, C₆-io aryl, and C₆-io heteroaryl may each be optionally substituted by optionally substituted C3-10 cycloalkyl, optionally substituted C_1-8 alkoxy, halo, cyano, carboxyl, optionally substituted C₆-io aryl,

optionally substituted C₆-io aryloxy,

In some embodiments, Ra and Rb, or Rb and R_c, or Ra and Rc, together form an optionally substituted ring system selected

from the group consi

[0209] Each Ri and Re of formula X-a and formula X-b is independently selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted alkoxyalkyl, optionally substituted alkenyl, optionally substituted heteroalkyl, optionally substituted heteroalkenyl, optionally substituted aryl, optionally substituted arylalkyl, optionally substituted heteroaryl, optionally substituted cylcoalkyl, optionally substituted cycloalkenyl, optionally substituted cycloheteroalkyl, optionally substituted cycloheteroalkenyl, optionally substituted amino, optionally substituted amido, optionally substituted cyclic amido, optionally substituted cyclic imido, optionally substituted alkoxy, optionally substituted carboxy, and optionally substituted carbonyl; or Ri and R_e together form an optionally substituted ring or an optionally substituted polycyclic ring system, wherein each ring is independently cycloalkyl, aryl, heterocyclyl, or heteroaryl.

[0210] Each Di , D₂, D3, and D4 of formula X-a and formula X-b is independently selected from the group consisting of hydrogen, optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted acyloxy, optionally substituted alkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted amino, amido, cyclic amido, and cyclic imido, -aryl-NR'R", -ary-aryl-NR'R", and -heteroaryl-heteroaryl-R'; wherein R' and R" are independently selected from the group consisting of optionally substituted alkyl, optionally substituted alkenyl, and optionally substituted aryl; or one or both of R' and R" forms a fused heterocyclic ring with aryl to which the N is attached to; provided that Di and D₂ are not both hydrogen, and Di and D₂ are not optionally substituted thiophene or optionally substituted furan.

[0211] In some embodiments, the chromophore is represented by formula X-a or formula X-b, wherein Di and D₂ are each independently selected from the group consisting of alkoxyaryl, -aryl-NR'R", and -aryl-aryl-NR'R"; wherein R' and R" are independently selected from the group consisting of alkyl and aryl optionally substituted by alkyl, alkoxy, or -C(=0)R; wherein R is optionally substituted aryl or optionally substituted alkyl; or one or both of R' and R" forms a fused heterocyclic ring with aryl to which the N is attached to.

[0212] In some embodiments, each of Di, D₂, D₃, and D4 in formula X-a and formula X-b are each independently C₆-io aryl or optionally substituted C₆-io aryl. The substituent(s) on the C₆-io aryl may be selected from the group consisting of -NR'R", -C₆-io aryl-NR'R", C_1-8 alkyl and C_1-8 alkoxy, wherein R' and R" are independently selected from the group consisting of C_1-8 alkyl, C_1-8 alkoxy, C₆-io aryl, C₆-io aryl-C_1-8 alkyl, C₆-io aryl-C_1-8 alkoxy, and C₆-io aryl-C(=0)R, wherein R is optionally substituted C_1-8 alkyl, optionally substituted C_1-8 alkoxy or optionally substituted C₆-io aryl; or one or both of R' and R" forms a fused heterocyclic ring with aryl to which the N is attached to.

[0213] In some e romophore is represented by formula X-a or

formula X-b, wherein Het₃ i

, provided that Di and D₂ are independently

-60-

hore is represented by formual X-a or

ided that Di and D₂ are not hydroxy or

[0216] In some embodiments, X in formula VIII, formula X-a, and formula X-b, is selected from the group consisting of -N(Ao)-, -S-, and -Se-

[0217] In some embodiments, Z in formula VIII, formula IX-a, and formula IX-b, is selected from the group consisting of -N(R_a)-, -S-, and -Se-

[0218] In some embodiments, Ao in formula VIII, formula IX-a, formula IX-b, formula X-a, and formula X-b, is selected from the group consisting of hydrogen, optionally substituted CMO alkyl, optionally substituted aryl, optionally substituted heteroaryl, and optionally substituted alkoxyalkyl. In some embodiments, Ao is selected from the group consisting of: hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl,

In some embodiments, Ao is hydrogen or C_1-8 alkyl . In some embodiments Ao is isobutyl. In some

embodiments Ao is tert-butyl. In some

In some

embodiments, Ao is

[0219] In some embodiments, R_a, or R_c, in formula VIII, formula IX-a, formula IX-b, formula X-a, and formula X-b, are independently selected from the group consisting of hydrogen, optionally substituted C_1-10 alkyl, optionally substituted aryl, optionally substituted heteroaryl, and optionally substituted alkoxyalkyl. In some embodiments R_a and R_b, or R_b and R_c, or R_a and R_c, together form an optionally substituted polycyclic ring system.

[0220] In some embodiments, R_a, R_b, or R_c, in formula VIII, formula IX-a, formula IX-b, formula X-a, and formula X-b, are independently selected from the group consisting of hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl,

hexyl,

[0221] In some embodiments, Ra and Rb, or Rb and R_c, together form one following ring structures

[0223] In some embodiments, at least one of the L in formula VIII is selected from the group consisting of: 1 ,2-ethylene, acetylene, 1 ,4-phenylene, 1 ,1 '-biphenyl-4,4'-diyl, naphthalene-2,6-diyl, naphthalene- 1 ,4-diyl, 9H-fiuorene-2,7-diyl, perylene-3,9-diyl, perylene-3,10-diyl, or pyrene-l ,6-diyl, lH-pyrrole-2,5-diyl, furan-2,5-diyl, thiophen-2,5-diyl, thieno[3,2-&]thiophene-2,5-diyl, benzo[c]thiophene-l ,3-diyl, dibenzo[^J]thiophene-2,8-diyl, 9H-carbozole-3,6-diyl, 9H-carbozole-2,7-diyl, dibenzo[¾,JJfuran-2,8-diyl, 10H- phenothiazine-3,7-diyl, and 10H-phenothiazine-2,8-diyl; wherein each moiety is optionally substituted.

[0224] With regard to L in any of the formulae above, the electron linker represents a conjugated electron system, which may be neutral or serve as an electron donor itself. In some embodiments, some examples are provided below, which may or may not contain

thieno[3,2-5]thiophene-2,5-diyl benzo[c]thiophene-1 ,3-diyl dibenzo[b,d]thiophene-2,8-diyl

9/-/-carbazole-3,6-diyl dibenzo[b,d]furan-2,8-diyl 10/-/-phenothiazine-3,7-diyl

etc. [0225] The above mentioned combination of chromophores is especially suitable for use in the solar cells and agriculture (greenhouse) applications because they are surprisingly more stable in harsh environmental conditions than currently available wavelength converting chromophores. This stability makes these chromophores advantageous in their use as wavelength conversion materials for solar cells and agriculture applications. Without such photostability, these chromophores would degrade and lose efficiency.

[0226] In some embodiments the photostability of chromophores can be measured by fabricating a wavelength conversion film containing the chromophore compound and then measuring the absorption peak prior to exposure and after exposure to continuous one sun (AM1.5G) irradiation at ambient temperature. The preparation of such a wavelength conversion film is described in the EXAMPLES section below. The amount of remaining chromophore after irradiation can be measured using the maximum absorption of the chromophore before and after irradiation using the following equation:

Absorption Peak Intensity After Irradiation

x 100% = % Chromophore Remaining

Absorption Peak Intensity Before Irradiation

The % degradation can be measured using the following equation:

(Absorption Peak Intensity Before Irradiation - Absorption Peak Intensity After Irradiation)

x 100% = % Chromophore Degraded

Absorption Peak Intensity Before Irradiation

Easily degraded chromophores typically show a substantial decay of the absorption peak within a few hours of one sun irradiation. Films with excellent photostability will maintain the peak absorption over a long time period of exposure to one sun irradiation. In some embodiments, a photostable chromophore shows less than about 30%, 20%, 15%, 10%, 5%, 2.5%, 1.0%, or 0.5% degradation in maximum absorption peak intensity after 24 hours of continuous one sun (AM1.5G) irradiation at ambient temperature. In some embodiments, a photostable chromophore has greater than about 70%, 80%, 85%, 90%, 95%, 97.5%, 99.0%, or 99.5% of the chromophore remaning (as measured by maximum absorption peak intensity) after 24 hours of continuous one sun (AM1.5G) irradiation at ambient temperature. [0227] In some embodiments, the total amount of the chromophore(s) in the photostable wavelength conversion material is in the range of about 0.01 % to about 3.0% by weight of the composition for forming a photostable wavelength conversion material. In some embodiments, the total amount of the chromophore(s) in the photostable wavelength conversion material is in the range of about 0.05% to about 1.0% by weight of the composition for forming a photostable wavelength conversion material. In some embodiments, the amount of each chromophore in the photostable wavelength conversion material is in the range of about 0.01% to about 3.0% by weight of the composition for forming a photostable wavelength conversion material. In some embodiments, the amount of each chromophore in the photostable wavelength conversion material is in the range of about 0.05% to about 1.0% by weight of the composition for forming a photostable wavelength conversion material.

[0228] In some embodiments, the composition for forming a photostable wavelength conversion material comprises a UV absorbing chromophore. In some embodiments, the UV absorbing chromophore can be used instead of or in addition to the at least one chromophore. In some embodiments, the UV absorbing chromophore is used in combination with the one or more additional chromophores as described above. Examples of

[0229] In some embodiments, the composition for forming a photostable wavelength conversion material comprises an IR absorbing chromophore. In some embodiments, the IR absorbing chromophore can be used instead of or in addition to the at least one chromophore. In some embodiments, the IR absorbing chromophore is used in combination with the one or more additional chromophores as described above.

[0230] As stated above, in some embodiments, the composition for forming a photostable wavelength conversion material comprises a second chromophore or additional chromophores in combination with the first chromophore. In some embodiments, the second chromophore or additional chromophores can be any of the chromophores defined above and may be in any combination independently selected from the other chromophores present in the composition.

[0231] In some embodiments, the first chromophore and, if present, the second chromophore are individually present in the wavelength conversion composition in an amount in the range from about 0.01 wt% to about 3.0 wt% of the composition (i.e. the first chromophore can be present in an amount from 0.01 wt% to about 3.0 wt% of the composition and the second chromophore can be present in an amount from 0.01 wt% to about 3.0 wt% of the composition). In some embodiments, the first chromophore and, if present, the second chromophore are individually present in the wavelength conversion composition in an amount in the range from about 0.05 wt% to about 1.0 wt% of the composition. In some embodiments, the first chromophore and, if present, the second chromophore are individually present in the wavelength conversion composition in an amount in the range of about 0.05 wt% to about 0.1 wt%, about 0.1 wt% to about 0.2 wt%, about 0.2 wt% to about 0.3 wt%, about 0.3 wt% to about 0.4 wt%, about 0.5 wt% to about 0.6 wt%, about 0.6 wt% to about 0.7 wt%, about 0.7 wt% to about 0.8 wt%, about 0.8 wt% to about 0.9 wt%, from about 0.9 wt% to about 1.0 wt%, from about 1.0 wt% to about 2.0 wt%, or from about 2.0 wt% to about 3.0 wt% of the composition.

[0232] In some embodiments, the total amount of all the chromophores present in the the wavelength conversion composition is in the range of about 0.05% to about 0.1%, about 0.1 % to about 0.2%, about 0.2% to about 0.3%, about 0.3% to about 0.4%, about 0.5% to about 0.6%, about 0.6% to about 0.7%, about 0.7% to about 0.8%, about 0.8% to about 0.9%, from about 0.9% to about 1.0%, from about 1.0% to about 2.0%, from about 2.0% to about 3.0%, from about 3.0% to about 5.0%, from about 5.0% to about 7.5%, or from about 7.5% to about 10.0% of the total weight of the composition.

[0233] Adhesion promoters can be used to improve the compatibility of two or more components in the mixture, or to improve the adhesion between a polymeric system and an optional filler material. Adhesion promoters are also known as compatibilizers, or coupling agents. In some embodiments, various adhesion promoters may be used in the composition for forming a photostable wavelength conversion material. In some embodiments, the adhesion promoter is a polymeric adhesion promoter.

[0234] In some embodiments, the composition comprises a first adhesion promoter. In some embodiments, the first adhesion promoter comprises an acrylic silane material, a vinyl silane material, an epoxy silane material, or an amino silane material. In some embodiments, the first adhesion promoter comprises a methacrylate silane material. In some embodiments, the first adhesion promoter comprises 3- Methacryl xypropyltrimethoxysilane, as given by the following formula:

[0235] In some embodiments, the composition further comprises a second adhesion promoter. In some embodiments, the second adhesion promoter may be any of the adhesion promoters described above and may be independently selected from the first adhesion promoter. In some embodiments, the composition further comprises 1 , 2, 3, 4, 5, or more additional adhesion promoters in combination with the first and second adhesion promoters. In some embodiments, the additional adhesion promoter(s) may be any of the adhesion promoters described above and may be independently selected from the first and second adhesion promoters.

[0236] The concentration of the first adhesion promoter may vary depending on the desired properties of the film. In some embodiments, the first adhesion promoter is present in the wavelength conversion composition in an amount in the range of about 0.001 % to about 2.0% by weight of the composition. In some embodiments, the first adhesion promoter is present in the wavelength conversion composition in an amount in the range from about 0.001 % to about 0.01 %, from about 0.01 % to about 0.1%, from about 0.1% to about 1.0%, or from about 1.0% to about 2.0% by weight of the composition. In some embodiments, the second adhesion promoter is present in the wavelength conversion composition in an amount in the range from about 0.001 % to about 2.0%, from about 0.001% to about 0.01%, from about 0.01% to about 0.1%, from about 0.1% to about 1.0%, or from about 1.0% to about 2.0% by weight of the composition.

[0237] In some embodiments, the total amount of adhesion promoters in the photostable wavelength conversion material is in the range of about 0.001 % to about 2.0% by weight of the composition. In some embodiments, the amount of each adhesion promoter in the photostable wavelength conversion material is in the range of about 0.001% to about 2.0% by weight of the composition.

[0238] Stabilizers for polymers are used to prevent the various effects such as oxidation, chain scission, and uncontrolled recombinations and crosslinking reactions that are caused by photo-oxidation of polymers. In some instances, polymers weather due to the direct impact of heat and ultraviolet light. The effectiveness of the stabilizers against weathering depends on the solubility, ability to stabilize in different polymer matrix, evaporation loss during processing and use. Stabilizers are also used to inhibit the reaction between two or more other chemicals. Stabilizers can also inhibit the separation (including phase separation) of suspensions, emulsions, and foams.

[0239] In some embodiments, various stabilizers may be used in the composition for forming a wavelength conversion material. In some embodiments, stabilizers include antioxidants which prevent unwanted oxidation of materials. In some embodiments, an emulsifier or surfactant is used for stabilization of the composition.

[0240] In some embodiments of the composition, the stabilizer comprises a light stabilizer. In some embodiments, an ultraviolet stabilizer is used to protect the composition from the harmful effects of ultraviolet radiation. Ultraviolet stabilizers include UV absorbers. The UV absorbers dissipate the absorbed light energy from UV rays as heat by reversible intramolecular proton transfer. This reduces the adsorption of UV rays by the polymer matrix and hence reduces the rate of weathering. Typical UV absorbers are oxanilides for polyamides, benzophenones for PVC, benzotriazoles and hydroxyphenyltriazines for polycarbonate. In some embodiments of the composition, the stabilizer comprises an oxanilide derivative, benzophenone derivative, benzotriazole derivative, hydroxyphenyltriazine derivative, or a polymerizable/crosslinkable (meth)acrylic derivative, or any combination thereof. Other light stabilizers include IR absorbers or IR reflective materials.

[0241] In some embodiments, light stabilizers that are scavengers may be used. Scavengers are compounds that eliminate the free radicals formed by ultraviolet radiation. Scavenger compounds include hindered amine light stabilizers (HALS). The ability of hindered amine light stabilizers to scavenge radicals which are produced by weathering, may be explained by the formation of nitroxy radicals. The nitroxy radical combines with free radicals in the polymers. Although hindered amine light stabilizers are traditionally considered as light stabilizers, they can also stabilize thermal degradation. Hindered amine light stabilizers have been found to be extremely effective in polyolefins, polyethylene, and polyurethane. Typical HALS compounds are derivatives of 2,2,6,6-tetramethyl piperidine. One advantage of the HALS is that no specific layer thickness or concentration limit needs to be reached to guarantee good results.

[0242] In some embodiments, any of the above recited scavengers may be used in the composition for forming a photostable wavelength conversion material. In some embodiments, significant levels of stabilization are achieved at relatively low concentrations. Various hindered amine light stabilizer materials may be used in the wavelength conversion composition. In some embodiments, the at least one stabilizer comprises a hindered amine light stabilizer (HALS). In some embodiments, the light stabilizer is a polymerizable compound. In some embodiments, the light stabilizer is a (meth)acrylic compound. In some embodiments, the stabilizer is a H or alkyl-substituted HALS. In some embodiments, the stabilizer is amino-ether ( -OR)-functionalized HALS. In some embodiments, the stabilizer is a derivative of 2-hydroxyphenyl-benzophenone. In some embodiments, the stabilizer is a derivative of 2-(2-hydroxyphenyl)-benzotriazole. In some embodiments, the stabilizer is a derivative of 2-hydroxyphenyl-s-triazine. In some embodiments, the stabilizer is a derivative of 2,2,6,6-tetramethyl piperidine (TMP). In some embodiments, the stabilizer is selected from the group consisting of the commercially available Tinuvin 144 (Di-(1 , 2,2,6,6- pentamethyl-4-piperidyl)-2-butyl-2-(3,5-di-tert-butyl-4-hydroxybenzyl)malonate), Tinuvin 292 (mixture of 5z^'s(l ,2,2,6,6-pentamethyl-4-piperidyl) sebacate and Methyl 1 ,2,2,6,6- pentamethyl-4-piperidyl sebacate), Tinuvin 622 (4-hydroxy-2,2,6,6-tetramethyl- l -piperidine ethanol-alt-l ,4-butanedioic acid), Chimassorb 1 19 (l ,3,5-Triazine-2, 4,6-triamine, N,N"'-1 ,2- ethanediylbis[N-[3-[[4,6- bis[butyl(l ,2,2,6,6-pentamethyl- 4-piperidinyl)amino]-l ,3, 5- triazin-2-yl]amino]propyl]- Ν',Ν''-dibutyl- N',N"-bis( l ,2,2,6,6-pentamethyl-4-piperidinyl), Chimassorb 944 (Poly[[6-[(l ,1 ,3,3-tetramethylbutyl)amino]- 1 ,3,5-triazine-2,4-diyl] [(2,2,6,6- tetramethyl-4-piperidinyl)imino]-l ,6-hexanediyl[(2,2,6,6-tetramethyl-4- piperidinyl)imino]])), Tinuvin 622 (Butanedioic acid, dimethylester, polymer with 4- hydroxy-2,2,6,6-tetramethyl-l -piperidine ethanol), Tinuvin 770 (Bis(2,2,6,6,-tetramethyl-4- piperidyl)sebaceate), Tinuvin 791 (mixture of Tinuvin 770 and Chimassorb 944), Tinuvin 783 (mixture of Tinuvin 622 and Chimassorb 944), Tinuvin 1 1 1 (Mixture of Tinuvin 622 and Chimassorb 1 19), Tinuvin NOR371 (Triazine derivative), and Stab LA-57 (tetrakis(2,2,6,6- pentamethyl-4-piperidyl) 1 ,2,3,4-butanetetracarboxylate).

[0243] In some embodiments, the composition comprises a first stabilizer. The first stabilizer may be selected from any of the stabilizers described above. In some embodiments, the composition further comprises a second stabilizer. The second stabilizer may be independently selected from any of the stabilizers described above to form any combination with the first stabilizer. In some embodiments, the composition further comprises 1 , 2, 3, 4, 5, or more additional stabilizers. The 1 , 2, 3, 4, 5, or more additional stabilizers may be independently selected from any of the stabilizers described above to form any combination with the first and second stabilizers.

[0244] In some embodiments, the concentration of the stabilizer may vary depending on the desired properties of the film. In some embodiments, the first stabilizer is present in the wavelength conversion composition an amount in the range of about 0.001% to about 2.0% by weight of the composition. In some embodiments, the first stabilizer is present in the wavelength conversion composition in an amount in the range from about 0.001% to about 0.01%, from about 0.01 % to about 0.1%, from about 0.1% to about 1.0%, or from about 1.0% to about 2.0% by weight of the composition.

[0245] In some embodiments, the second stabilizer, if present, is present in the wavelength conversion composition an amount in the range of about 0.001% to about 2.0% by weight of the composition. In some embodiments, the second stabilizer, if present, is present in the wavelength conversion composition in an amount in the range from about 0.001% to about 0.01%, from about 0.01 % to about 0.1%, from about 0.1% to about 1.0%, or from about 1.0% to about 2.0% by weight of the composition.

[0246] In some embodiments, the total amount of stabilizers in the photostable wavelength conversion material is in the range of about 0.001% to about 2.0% by weight of the composition. In some embodiments, the amount of each stabilizer in the photostable wavelength conversion material is in the range of about 0.001% to about 2.0% by weight of the composition.

[0247] In some embodiments, the composition for forming a photostable wavelength conversion material further comprises a first antioxidant. In some embodiments, it is useful to incorporate an antioxidant into the wavelength conversion composition. In some embodiments, antioxidants are used to terminate the oxidation reactions taking place due to different weathering conditions and reduce the degradation of organic materials. For example, synthetic polymers react with atmospheric oxygen. Organic materials undergo auto-oxidizations due to free radical chain reaction. Oxidatively sensitive substrates will react with atmospheric oxygen directly and produce free radicals.

[0248] Weathering of polymers can be caused by absorption of UV lights, which results in, radical initiated auto-oxidation. This produces cleavage of hydro peroxides and carbonyl compounds. This is because of the weak bond in hydro peroxides which is the main source for the free radicals to initiate from. Homolytic decomposition of hydro peroxide increases the rate of free radicals production. Therefore it is an important factor in determining oxidative stability. The conversion of peroxy and alkyl radicals to non-radical species terminates the chain reaction, thereby decreasing the kinetic chain length. Hydrogen- donating antioxidants, such as hindered phenols and secondary aromatic amines, inhibit oxidation by competing with the organic substrate for peroxy radicals, thereby terminating the chain reaction and stabilizing the further oxidation reactions. Benzofuranone derivatives are another effective antioxidant, which terminates the chain reaction by donating weakly bonded benzylic hydrogen atom and gets reduced to a stable benzofuranyl (lactone). Antioxidants inhibit the formation of the free radicals thereby enhancing the stability of polymers against light and heat.

[0249] In some embodiments, the first antioxidant comprises a phenolic antioxidant, a phosphite antioxidant, or a thioether antioxidant. In some embodiments, the first antioxidant is selected from the commercially available group consisting of Irganox 1010 (Pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate)), Irganox 1076 (Octadecyl-3-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionate), butylated hydroxytoluene (BHT), Irgfos 168 (Tris(2,4-ditert-butylphenyl)phosphite), Irganox PS 800 (Didodecyl 3,3'-thiodipropionate), and Irganox PS 802 (Dioctadecyl 3,3'-thiodipropionate). In some embodiments, the first antioxidant is present in an amount in the range of about 0.001% to about 0.5% by weight of the composition. In some embodiments, the first antioxidant is present in an amount in the range of about 0.01 % to about 0.1% by weight of the composition. In some embodiments, the first antioxidant is present in the wavelength conversion composition in an amount in the range from about 0.001% to about 0.005%, from about 0.005% to about 0.01%, from about 0.010% to about 0.05%, or from about 0.05% to about 0.1 % by weight of the composition.

[0250] In some embodiments, the composition for forming a photostable wavelength conversion material further comprises a second antioxidant in combination with the first antioxidant. In some embodiments, the second antioxidants can be any of the antioxidant compounds described above and may be in any combination independently selected from the first antioxidant. In some embodiments, the composition for forming a photostable wavelength conversion material further comprises 1 , 2, 3, 4, 5, or more additional antioxidants independently selected from any of the antioxidants described above. In some embodiments, the total amount of antioxidants in the photostable wavelength conversion material is in the range of about 0.001% to about 0.5% by weight of the composition. In some embodiments, the total amount of antioxidants in the photostable wavelength conversion material is in the range of about 0.001% to about 0.5% by weight of the composition. In some embodiments, the amount of each antioxidant in the photostable wavelength conversion material is in the range of about 0.001% to about 0.5% by weight of the composition. In some embodiments, the amount of each antioxidant in the photostable wavelength conversion material is in the range of about 0.001% to about 0.5% by weight of the composition.

[0251] In some embodiments, the composition for forming a photostable wavelength conversion material further comprises at least one IR reflective agent. In some embodiments, it is useful to incorporate an IR reflective agent into the wavelength conversion composition. In some embodiments, the IR reflective agent comprises metal oxide, mica powder, composite oxide, Talc, titania, ceria, zirconia, silica, magnesia, clay, Kaolin, alumina, infrared pigment, or any combination thereof. In some embodiments, the IR reflective agent is present in an amount in the range of about 0.01% to about 30% by weight of the composition. In some embodiments, the IR reflective agent is present in an amount in the range of about 0.01 % to about 10% by weight of the composition.

[0252] Advantageously, some embodiments of the disclosed polymer matrices of the wavelength conversion film are optically transparent. Optical transparency improves the transmittance of light through the wavelength conversion film allowing more energy to be captured from the light. Additionally, when used as, for example, a window, the additional light that travels through the wavelength conversion film results enhanced brightness through the window. In some embodiments, an optically transparent polymer matrix (absent a chromophore) allows transmission of greater than about 80%, 90%, 95%, 97.5%, 99.0%, 99.5%, or 99.9% of the visible light spectrum.

[0253] In some embodiments, the composition for forming a photostable wavelength conversion material is substantially free of oxide microparticles, wherein substantially free of oxide microparticles means that oxide microparticles have not been deliberately added to the composition. In some embodiments, the composition for forming a photostable wavelength conversion material is essentially free of oxide microparticles, meaning that oxide microparticles cannot be detected in the composition. In some embodiments, the composition for forming a photostable wavelength converstion material is free of oxide microparticles. In some embodiments, the at least one chromophore is not used in combination with a oxide microparticle.

[0254] In some embodiments, the composition for forming a photostable wavelength conversion material further comprises oxide microparticles.

[0255] In some embodiments, the composition for forming a photostable wavelength conversion material further comprises one or more of an IR reflector, an IR absorber, an anti-fog agent, an anti-mist agent, an anti-drop agent, anti-dust agent, a lubricant, a modifier, an inorganic filler, an anti-static agent, or any combination thereof. Anti-fog or anti-mist agents are generally non-ionic surfactants. Anti-dust or anti-static agents can be used to prevent dust or dirt accumulation on a polymer film surface. [0256] In some embodiments, the composition for forming a photostable wavelength conversion material may be specifically designed for greenhouse roofing applications. In some embodiments, the composition for forming a photostable wavelength conversion material comprises Ethylene methyl methacrylate copolymer (EMMA) obtained from Sumitomo Chemicals (Acryft WK307). In some embodiments, the methyl methacrylate (MMA) content in the EMMA is in the range of 5 to 32 parts by weight, and, in some embodiments, in the range of 10 to 25 parts by weight, based on 100 parts by weight of EMMA. In some embodiments, the composition for forming a photostable wavelength conversion material comprises the stabilizer tetrakis(,2,2,6,6-pentamethyl-4- piperidinyl)l ,2,3,4-butanetetracarboxylate (Stab LA-57) from Adeka. In some embodiments, the composition for forming a photostable wavelength conversion material comprises UV absorbers such as 2-Hydroxy-4-(octyloxy)benzophenone (Chimassorb 81) and 2,2'- Methylenebis[6-(2H-benzotriazol-2-yl)-4-(l ,l ,3,3-tetramethylbutyl)phenol] Tinuvin 360 from BASF.

[0257] In some embodiments, a wavelength conversion material or layer may be formed by curing a layer of the above described compositions. This cured material or layer may be used for forming a photostable wavelength conversion device. In some embodiments, the layer is cured at a temperature of between about 130 to about 180 degrees Celsius. In some embodiments, the layer is cured at a temperature of between about 140 to about 160 degrees Celsius. In some embodiments, the layer is cured at a temperature of between about 130°C and about 145°C, about 145°C to about 160°C, or about 160°C to about 180°C.

[0258] In some embodiments, the curing time for the wavelength conversion layer depends on the temperature. When the cure temperature is high, the cure time is low, while lower cure temperatures require longer curing times. In some embodiments, the wavelength conversion layer is cured for a time of about 5 to about 100 minutes. In some embodiments, the wavelength conversion layer is cured for a time of about 10 to about 50 minutes. In some embodiments, the wavelength conversion layer is cured for a time of about 10 to about 45 minutes. In some embodiments, the wavelength conversion layer is cured for a time of about 5 minutes to about 10 minutes, from about 10 minutes to about 20 minutes, from about 20 minutes to about 30 minutes, from about 30 minutes to about 40 minutes, from about 40 to about 50 minutes, from about 50 to about 60 minutes, from about 60 minutes to about 70 minutes, from about 70 minutes to about 80 minutes, or from about 80 minutes to about 90 minutes.

[0259] The wavelength conversion layer described herein may be prepared in various ways, e.g., by polymerization or crosslinking of the corresponding component monomers or precursors thereof. Polymerization may be carried out by methods known to a skilled artisan, as informed by the guidance provided herein.

[0260] In some embodiments, the composition for forming a photostable wavelength conversion material for a solar energy conversion device, can be prepared in a conventional manner by free-radical copolymerization with the monomers in suitable solvents, such as, for example, hydrocarbons, such as n-hexane, aromatic hydrocarbons, such as toluene or xylene, halogenated aromatic hydrocarbons, such as chlorobenzene, ethers, such as tetrahydrofuran and dioxane, ketones, such as acetone and cyclohexanone and/or dimethylformamide, and alcohols, at elevated temperatures, in general in the range from about 30° C to about 100° C, or from about 40° to about 60° C, or from about 50° to about 80° C. In some embodiments, the reaction is performed in the absence of water and air.

[0261] Various methods may be used to incorporate the chromophore into the composition for forming a photostable wavelength conversion material. In some embodiments, the chromophore can be attached to the optically transparent crosslinkable polymer in one or more side chains. In some embodiments, the chromophore can be incorporated into the wavelength conversion composition as a separate compound. In some embodiments of the wavelength conversion composition, the chromophore may be doped into the composition such that the polymer and the chromophore are not chemically bonded. In some embodiments of the composition for forming a photostable wavelength conversion material, one or more of the chromophores may be covalently bonded to the optically transparent crosslinkable polymer.

[0262] Various known methods may be used to covalently bond the chromophore into to the polymer matrix of the composition. In some embodiments, free radical polymerization is used to covalently bond the optically transparent crosslinkable polymer matrix and the chromophore together. [0263] In some embodiments, the chromophore can be attached to the polymer backbone in one or more side chains. In some embodiments, the chromophore can be incorporated into the wavelength conversion composition as a separate compound.

[0264] In some embodiments, the composition for forming a photostable wavelength conversion material can be formed into self-supporting films or layers. However, in some embodiments, the wavelength conversion composition can be formed into films or layers that are applied to support materials. This can be carried out by various techniques known in the art. In some embodiments, the method being selected depending on whether a thick or thin film is desired. Thin films can be produced, for example, by spin coating or casting from solutions or melts, while thicker coatings can be produced from prefabricated cells, by hot pressing, extruding or injection molding.

[0265] In some embodiments, the composition for forming a photostable wavelength conversion material is formed into a thin film or layer. The method for forming the composition for forming a photostable wavelength conversion material into a thin film may be appropriately selected from known methods used to produce thin films. Specific examples thereof include cast- and calendar-film extrusion, injection molding, roll coating, kiss roll coating, gravure coating, reverse coating, roll brush coating, spray coating, dip roll coating, bar coating, knife coating, and air knife coating.

[0266] In some embodiments the composition for forming a photostable wavelength conversion material may be coated onto an optically transparent substrate. The optically transparent substrate may be plastic or glass.

Encapsulation Structure for Solar Energy Conversion Device

[0267] Some embodiments of the invention provide an encapsulation structure for a solar energy conversion device. In some embodiments the encapsulation structure comprises the wavelength conversion layer formed from a composition as described above. In some embodiments the wavelength conversion layer is configured to encapsulate the solar energy conversion device and inhibit penetration of moisture and oxygen into the solar energy conversion device. In some embodiments, the wavelength conversion layer is configured to encapsulate the solar energy conversion device such that light must pass through the wavelength conversion layer prior to reaching the solar energy conversion device.

[0268] Some embodiments of the invention provide an encapsulation structure for a solar energy conversion device comprising a wavelength conversion layer and an environmental protective cover. In some embodiments, the environmental protective cover is configured to inhibit penetration of moisture and oxygen into the wavelength conversion layer and the solar energy conversion device. In some embodiments the environmental protective cover comprises plastic or glass sheets. In some embodiments, a sealing tape is applied to the perimeter of the solar energy conversion device to inhibit the ingress of oxygen and moisture from the edges. Example embodiments of this encapsulate structure applied to solar cell energy conversion devices are illustrated in Figures 1-6.

[0269] Some embodiments of the invention provide an encapsulation structure for a solar energy conversion device comprising a wavelength conversion layer. In some embodiments, the wavelength conversion layer also acts as an environmental protector to prevent moisture and oxygen penetration into the solar cell. In some embodiments the wavelength conversion layer is designed to prevent oxygen and moisture penetration into the solar cell, such that an additional environmental protection cover is not needed, and the material also enhances the solar harvesting efficiency of the cell. Example embodiments of this encapsulate structure applied to solar energy conversion devices are illustrated in Figures 7-9.

[0270] In some embodiments, the encapsulation structure further comprises a sealing tape around the perimeter of the solar energy conversion device. In some embodiments, the encapsulation structure further comprises one or more of glass sheets, reflective backsheets, edge sealing tape, frame materials, polymer encapsulation materials, or adhesive layers to adhere additional layers to the system. In some embodiments, the encapsulation structure further comprises an additional polymer layer containing a UV absorber.

[0271] Additional forms of the wavelength conversion composition are also possible, as well as additional methods of applying the wavelength conversion composition to the solar energy conversion devices. The encapsulation structure may be applied to rigid devices or it may be applied to flexible devices. Furthermore, the encapsulation structure can be used to improve the performance of multiple solar cells or photovoltaic devices. For example, in an embodiment, the encapsulation structure comprises a plurality of solar cells or photovoltaic devices.

[0272] Additional materials may also be utilized to provide increased environmental protection. Glass or plastic sheets are often used as an environmental protective cover and may be applied both on top of and/or underneath the solar energy conversion devices once encapsulated with the wavelength conversion composition. A sealing tape may be applied to the perimeter of the device to prevent ingress of oxygen or moisture through the sides. A back sheet may also be used underneath the solar module devices to reflect and refract incident light that was not absorbed by the solar cell. The encapsulated solar energy conversion devices may also be put in a frame, such as those utilized to form solar panels or solar strings. Figures 10 and 1 1 illustrate example embodiments of the encapsulation structure used in a solar module device.

[0273] In some embodiments, the encapsulation structure further comprises additional layers which contain a light stabilizer, antioxidant, or UV absorber. In some embodiments, an additional polymer layer is used in the encapsulation structure which further comprises a light stabilizer, antioxidant, or UV absorber.

[0274] In some embodiments, the glass or polymer sheets used as an environmental cover may also further comprise a strong UV absorber to block harmful high energy radiation. In some embodiments, additional materials or layers may be used in the structure such as glass sheets, reflective and/or thermally conductive backsheets, edge sealing tape, frame materials, polymer materials, or adhesive layers to adhere additional layers to the system. In some embodiments, the edge sealing tape comprises a butyl material. In some embodiments, the frame materials comprise a metal.

[0275] Solar harvesting devices may also be rigid or flexible. Rigid devices include Silicon based solar cells. Flexible solar devices are often made out of organic thin films and may be used on clothing, tents, or other flexible substrates. Therefore, in an embodiment, the encapsulation structure can be applied to rigid devices or flexible devices.

[0276] An embodiment of an encapsulation structure is illustrated in Figure 1 , comprising a single solar cell device 100 encapsulated by laminating the cell on both sides with films of the wavelength conversion composition 101, which comprises at least one chromophore 102, an optically transparent crosslinkable polymer, an adhesion promoter, a stabilizer, a coagent, and a peroxide. Glass or plastic films can be used as the environmental protective cover 103, and the sides are taped with sealing tape 104 to prevent ingress of oxygen and moisture.

[0277] Another embodiment of an encapsulation structure is illustrated in Figure

2, which shows a plurality of solar cell devices 100 encapsulated by laminating the cells on both sides with films of the wavelength conversion composition 101, which comprises at least one chromophore 102, an optically transparent crosslinkable polymer, an adhesion promoter, a stabilizer, a coagent, and a peroxide, and wherein, glass or plastic films are used as the environmental protective cover 103, and the sides are taped with sealing tape 104 to prevent ingress of oxygen and moisture.

[0278] Another embodiment of an encapsulation structure is illustrated in Figure

3, which shows a plurality of solar cell devices 100 encapsulated by laminating the cell on both sides with a pure polymer encapsulate 105, then laminating the wavelength conversion composition 101 on top of the pure polymer encapsulate. The wavelength conversion composition 101 comprises at least one chromophore 102, an optically transparent crosslinkable polymer, an adhesion promoter, a stabilizer, a coagent, and a peroxide, and wherein, glass or plastic films are used as the environmental protective cover 103, and the sides are taped with sealing tape 104 to prevent ingress of oxygen and moisture.

[0279] Another embodiment of an encapsulation structure is illustrated in Figure

4, which shows a plurality of solar cell devices 100 encapsulated by laminating the cell on the light incident surface with a film of the wavelength conversion composition 101, which comprises at least one chromophore 102, an optically transparent crosslinkable polymer, an adhesion promoter, a stabilizer, a coagent, and a peroxide. A back sheet 106 is used underneath the solar cells, glass or plastic films are used as the environmental protective cover 103, and the sides are taped with sealing tape 104 to prevent ingress of oxygen and moisture.

[0280] Another embodiment of an encapsulation structure is illustrated in Figure

5, which shows a plurality of solar cell devices 100 encapsulated by laminating the cell on both sides with a pure polymer encapsulate 105, then laminating the wavelength conversion composition 101 on top of the pure polymer encapsulate. The wavelength conversion composition comprises at least one chromophore 102, an optically transparent crosslinkable polymer, an adhesion promoter, a stabilizer, a coagent, and a peroxide. A back sheet 106 is used underneath the solar cells, glass or plastic films are used as the environmental protective cover 103, and the sides are taped with sealing tape 104 to prevent ingress of oxygen and moisture.

[0281] Another embodiment of an encapsulation structure is illustrated in Figure

6, which shows a plurality of solar cell devices 100 encapsulated by laminating the cell on one side with a pure polymer encapsulate 105, then laminating the wavelength conversion composition 101 on top of the pure polymer encapsulate. The wavelength conversion composition 101 comprises at least one chromophore 102, an optically transparent crosslinkable polymer, an adhesion promoter, a stabilizer, a coagent, and a peroxide. An additional pure polymer encapsulate layer 105, which may contain a UV absorber to block harmful high energy irradiation, is laminated on top of the wavelength conversion composition, and glass or plastic films are used as the environmental protective cover 103, and the sides are taped with sealing tape 104 to prevent ingress of oxygen and moisture.

[0282] Another embodiment of an encapsulation structure is illustrated in Figure

7, which shows a single solar cell device 100 encapsulated in the wavelength conversion composition 101, which comprises at least one chromophore 102, an optically transparent crosslinkable polymer, an adhesion promoter, a stabilizer, a coagent, and a peroxide, and wherein the wavelength conversion composition also acts as an environmental protective against oxygen and moisture penetration to the cell.

[0283] Another embodiment of an encapsulation structure is illustrated in Figure

8, which shows a plurality of solar cell devices 100 encapsulated in the wavelength conversion composition 101, which comprises at least one chromophore 102, an optically transparent crosslinkable polymer, an adhesion promoter, a stabilizer, a coagent, and a peroxide, and wherein the wavelength conversion composition also acts as an environmental protective against oxygen and moisture penetration to the cell.

[0284] Another embodiment of an encapsulation structure is illustrated in Figure

9, which shows a plurality of solar cell devices 100 encapsulated by laminating the cell on the light incident side with a pure polymer encapsulate 105, then laminating the wavelength conversion material 101 on top of the pure polymer encapsulate. The wavelength conversion composition 101 comprises at least one chromophore 102, an optically transparent crosslinkable polymer, an adhesion promoter, a stabilizer, a coagent, and a peroxide, and wherein the wavelength conversion composition also acts as an environmental protective against oxygen and moisture penetration to the cell. Glass or plastic films are used as the bottom environmental protective cover 103, and the sides are taped with sealing tape 104 to prevent ingress of oxygen and moisture.

[0285] Another embodiment of an encapsulation structure is illustrated in Figure

10, which shows a solar panel constructed with several solar cell devices 100, a wavelength conversion composition 101 encapsulating the solar cell devices, a glass bottom sheet 103 and a glass top sheet 103 are used as the environmental protective covers 103, a back sheet 106 is underneath the bottom glass sheet and a frame 107 holds the module together.

[0286] Another embodiment of an encapsulation structure is illustrated in Figure

1 1 , which shows a solar panel constructed with several solar cell devices 100, a wavelength conversion composition 101 encapsulating the solar cell devices, a back sheet 106 is underneath the light incident surface of the solar cell devices, a glass top sheet 103 is adhered to the top of the module, and a frame 107 holds the module together.

[0287] Some embodiments of the invention provide a method of improving the performance of a solar energy conversion device. Solar energy conversion devices include any type of photovoltaic device, solar cell, solar module, or solar panel. In some embodiments, the method of improving the performance of a solar energy conversion device comprises encapsulating the device with the encapsulation structure disclosed herein. The encapsulation structure comprises the wavelength conversion composition. In some embodiments, the solar energy conversion device contains at least one device selected from the group consisting of a III-V or II-VI PN junction device, a Copper-Indium-Gallium- Selenium (CIGS) thin film device, an organic sensitizer device, an organic thin film device, or a Cadmium Sulfide/Cadmium Telluride (CdS/CdTe) thin film device, an amorphous Silicon solar cell, a microcrystalline Silicon solar cell, a crystalline Silicon solar cell, or a polycrystalline Silicon solar cell. In some embodiments the wavelength conversion composition of the encapsulation structure may be cast onto the solar energy conversion device and cured in place. In some embodiments the wavelength conversion composition of the encapsulation structure may be in the form of film(s) or layer(s). In some embodiments, the wavelength conversion composition, in the form of a thin film, may be roll laminated onto the solar energy conversion devices, wherein only a front layer is laminated onto the solar energy conversion devices, or both a front and back layer are laminated onto the solar energy conversion devices.

[0288] In some embodiments of the method, additional material layers may also be used in the encapsulation structure. For example, glass or plastic sheets may be used to provide additional environmental protection. Back sheets may be used to provide reflection and/or refraction of photons not absorbed by the solar cells. Adhesive layers may also be needed. For instance, an adhesive layer in between the wavelength conversion composition and the glass sheets which is used to adhere these two layers together. Other layers may also be included to further enhance the photoelectric conversion efficiency of solar modules. For example, a microstructured layer may also be provided on top of the encapsulation structure or in between the wavelength conversion composition and a glass sheet, which is designed to further enhance the solar harvesting efficiency of solar modules by decreasing the loss of photons to the environment which are often re-emited from the chromophore after absorption and wavelength conversion in a direction that is away from the photoelectric conversion layer of the solar module device. A layer with various microstructures on the surface (i.e. pyramids or cones) may increase internal reflection and refraction of the photons into the photoelectric conversion layer of the solar cell device, further enhancing the solar harvesting efficiency of the device.

[0289] In an embodiment the wavelength conversion composition comprising at least one chromophore, an optically transparent crosslinkable polymer, an adhesion promoter, a stabilizer, a coagent, and a peroxide, is applied to solar cell devices by first mixing the components of the wavelength conversion composition in a suitable solvent (toluene, cyclopentanone, etc.) to form a liquid or gel, applying the mixture to a solar cell matrix arranged on a removable substrate using standard methods of application, such as spin coating or drop casting, then curing the mixture to a solid form (i.e. heat treating, UV exposure, etc.) as is determined by the formulation design.

[0290] In another embodiment the wavelength conversion composition comprising at least one chromophore, an optically transparent crosslinkable polymer, an adhesion promoter, a stabilizer, a coagent, and a peroxide, is applied to solar cell devices by first synthesizing a wavelength conversion thin film or layer, and then adhering the wavelength conversion layer to the solar cell devices using an optically transparent and photostable adhesive and/or laminator. The wavelength conversion layer can be applied first on top of and then on bottom of the solar cells, to completely encapsulate the cells. The wavelength conversion layer can also be applied to just the top surface, wherein the bottom surface of the solar cells are secured to a substrate, such as a back sheet, and the wavelength conversion layer is applied to the top surface of the solar cells and the portion of the substrate that does not have solar cells attached to it.

[0291] Synthetic methods for forming the encapsulation structure are not restricted. Synthetic methods for the wavelength conversion layer are not restricted, but may follow the example synthetic procedures described as Scheme 1 and Scheme 2 detailed below.

Scheme 1 : wet processing general procedure for forming the WLC layer

[0292] In some embodiments, a wavelength conversion layer 101, which comprises at least one chromophore 102, an optically transparent crosslinkable polymer, a crosslinking reagent and optionally an adhesion promoter, a stabilizer, a coagent, and a peroxide, is fabricated into a film structure. The wavelength conversion layer can be fabricated by (i) preparing a polymer solution by dissolving polymer powder or pellets in a soluble solvent such as hydrocarbons, aromatic hydrocarbons, or alcohols, such as cyclopentanone, dioxane, etc., at a predetermined ratio; (ii) preparing a chromophore solution by dissolving the chromophore in the same solvent as the polymer solution at a predetermined concentration; (iii) preparing a stabilizer solution by dissolving a stabilizer in the same solvent as the polymer solution at a predetermined concentration; (iv) preparing a wavelength conversion (WLC) solution by mixing the polymer solution with the chromophore solution and the stabilizer solution, and then adding the adhesion promoter, the coagent, and the peroxide (crosslinking reagent), independently and at a predetermined weight ratio; and (v) forming the wavelength conversion layer by directly casting the wavelength conversion solution onto a non-stick polymer sheet or transferring the WLC solution to a non-stick PTFE dish, then drying the WLC solution at room temperature (or at about 25 to 45 °C) for at least 24 hours and further drying the mixture under vacuum at 40-70 °C for 3-6 hours, completely removing the remaining solvent by further vacuum hot pressing at 80-140°C for 5- 10min; (vi) the film thickness can be adjusted as desired during hot pressing.

Scheme 2: dry processing general procedure for forming the WLC layer

[0293] In some embodiments, a wavelength conversion layer 101, which comprises at least one chromophore 102, an optically transparent crosslinkable polymer, a crosslinking reagent and optionally an adhesion promoter, a stabilizer, a coagent, and a peroxide, is fabricated into a film structure. The wavelength conversion layer is fabricated by (i) mixing polymer powders or pellets, the at least one chromophore, and the stabilizer together at a predetermined ratio by a mixer at a temperature below the half decay temperature of the peroxide for a certain time, then adding the adhesion promoter, the coagent, and the peroxide, together at a predetermined ratio to the mixture and further mixing for a certain time as determined by the extent of desired crosslinking for the particular composition; (ii) then hot pressing the mixture under vacuum at 80-140°C for 3-10 min to a predetermined thickness; (vi) the film thickness can be adjusted as desired during hot pressing.

[0294] Once the WLC layer is formed it needs to be cured at an elevated temperature to induce crosslinking. In some embodiments, the curing temperature is from about 130 to about 180 degrees Celsius. In some embodiments, the curing time ranges from about 5 minutes to about 90 minutes.

[0295] In some embodiments, the wavelength conversion film, once formed, is easily attached to the light incident surface of a solar energy conversion device by pressing or laminating. In some embodiments, an adhesive may be needed to attach the wavelength conversion film to the solar energy conversion device. In some embodiments, once the wavelength conversion film is formed it is adhered to the solar module devices using an optically transparent and photostable adhesive. Greenhouse Panel

[0296] Additional uses for the wavelength conversion composition include greenhouse roofing materials. Plants use the energy in sunlight to convert carbon dioxide from the atmosphere and water into simple sugars. Plants then use these sugars as structural building blocks. Sugars form the main structural component of the plant. It is understood that plants react differently to the intensity and wavelengths of the light during their development. Improved plant growth is achieved using light in the violet-blue region and in the orange-red region. Light in the green region is usually not used by the plant (and is often reflected by the leaves).

[0297] In some instances, photovoltaic devices (e.g. solar cells) have been incorporated into greenhouse roofing materials to convert incident solar radiation to electricity. This electricity is then used for other applications within the greenhouse system. While the utilization of solar energy offers a promising alternative energy source, the use of photovoltaic modules lowers the amount of available light for the plant species.

[0298] A significant amount of development effort is ongoing to find greenhouse roofing materials with photovoltaic devices which provide sufficient electrical generation efficiency and the desired plant growth for an acceptable cost. For instance, a polymer sheeting comprising an inorganic luminescent material, yttrium-europium, is described for use in greenhouses. However, the cost to synthesize these inorganic luminescent compounds is considerably higher than the cost to synthesize organic luminescent compounds, and therefore may not be feasible. The use of greenhouse roofing materials which incorporate organic luminescent dyes has not been possible due to the poor photostability of these dyes, with the known commercially available dyes exhibiting photobleaching typically within days of exposure to solar radiation.

[0299] The use of a luminescent dye in greenhouse roofing materials, has typically comprised down-shifting dyes, which causes the shorter wavelength light to become excited and re-emitted within the luminescent panel at a longer (higher) more favorable wavelength. It is well established that plant species growth occurs with the exposure of the plant to blue light and red light. Typically, plants do not use green light, and either absorb this light as heat, or reflect it away. Additionally, the UV portion of the spectrum is not only not used by most plant species, but is usually quite harmful to the plant. Elimination of the UV portion of light is often done by incorporating a UV absorber into the roofing material to absorb all of the UV radiation, effectively removing it from the spectrum that reaches the plant inside the greenhouse. Because UV is so harmful to plant species, blocking the UV portion of light may enhance plant growth. However, this solar energy is then lost to the environment as heat. Previous attempts to further enhance plant growth have incorporated a luminescent dye into greenhouse roofing panels which converts green light into red light, basically increasing the usuable solar energy that is directed to the plant. The conversion and use of the UV wavelengths of light for greenhouses has not been reported.

[0300] In some embodiments of the present invention, organic photostable chromophores that can convert UV energy into blue light have been found to further enhance plant growth by further increasing the amount of usuable light available to the plant.

[0301] Some embodiments provide a greenhouse panel. In some embodiments the greenhouse panel comprises at least one wavelength conversion layer, wherein the wavelength conversion layer is formed by curing a layer of the composition for forming a photostable wavelength conversion material.

[0302] The greenhouse panel is useful as a greenhouse roof to provide improved wavelength profiles and plant growth that are photostable for long periods of time.

In some embodiments, the greenhouse panel comprises at least one organic photostable chromophore compound. In some embodiments, the greenhouse panel comprises at least two organic photostable chromophore compounds. In some embodiments, in embodiments with at least two chromophore compounds, the chromophore compounds comprise an organic photostable chromophore (A), which has an wavelength absorbance maximum in the UV wavelength range and has an wavelength emission maximum in the blue wavelength range, and another organic photostable chromophore (B), which has an wavelength absorbance maximum in the green wavelength range and has an wavelength emission maximum in the red wavelength range. In some embodiments, the two chromophores may be mixed in the same wavelength conversion layer. In some embodiments, when more than one wavelength conversion layer is present, the two chromophores may be in different wavelength conversion layers. In some embodiments, the at least one wavelength conversion layer further comprises an optically transparent crosslinkable polymer, and at least one crosslinking reagent. [0303] In some embodiments, it may be desirable to use chromophores in which the absorption and emission spectrums do not overlap. This helps to minimize re-absorption of photons, and improves efficiency. For instance, in some embodiments, the emission spectrum of (A) and the absorption spectrum of (B) have minimal overlap. In some embodiments, minimal overlap is an overlap ranging from about 0% to about 3%, from about 3% to about 5%, from about 5% to about 10%, from about 10% to about 15%, from about 15% to about 25%, or from about 25% to about 35%, where the percent overlap is a measure of the the area under the portion of over lapping spectra divided by the area under either the emission or absorption curve. In some embodiments, minimal overlap is less than about 35%, 30%, 25%, 20%, 15%, 10%, 5%, 3%, 2%, or 1 %.

[0304] There is no limit to the number of chromophores that can be used in the greenhouse panel. In some embodiments, the two chromophores (A) and (B) are mixed into one wavelength conversion layer. In some embodiments, the two chromophores (A) and (B) are located in separate wavelength conversion layer(s). In some embodiments, additional chromophores may be incorporated into the greenhouse panel to provide the desired properties. In some embodiments, the chromophores utilized in the greenhouse panel may be tailored to provide specific emission spectrums which are optimal to the specific plant species that is to be grown within the greenhouse. In some embodiments, the wavelength conversion layer(s) comprises three or more chromophores. In some embodiments, the wavelength conversion layer(s) comprises four or more chromophores. In some embodiments, the wavelength conversion layer(s) comprises five or more chromophores.

[0305] There is also no requirement on the location in which the chromophores may be placed in the greenhouse panel with respect to the incident solar light. In some embodiments, chromophore (A) may be in a wavelength conversion layer that receives the incident solar energy before the wavelength conversion layer comprising chromophore (B). In some embodiments, chromophore (B) may be in a wavelength conversion layer that receives the incident solar energy before the wavelength conversion layer comprising chromophore (A). In some embodiments, it may be desirable to have the wavelength conversion layer comprising chromophore (A) receive the solar energy first. In some embodiments, chromophore (A) acts to convert UV wavelengths to blue wavelengths. Chromophore compounds often degrade much faster when exposed to UV wavelengths. Therefore, by having the wavelength conversion layer comprising chromophore (A) exposed to the incident solar radiation first, much of the UV light can be converted to blue light, and the underlying layers will not be exposed to the UV light. This conversion of UV light effectively increases the stability of the wavelength conversion layer comprising chromophore (B) by reducing the exposure of this layer to UV radiation. Therefore, in some embodiments, the wavelength conversion layers are placed in ascending order of their wavelength absorption properties.

[0306] In some embodiments, the greenhouse panel may further comprise glass or polymer layers. The glass or polymer layers may act to protect the wavelength conversion layer or layers. The glass or polymer layers may also act as a substrate with which to adhere the wavelength conversion layer or layers onto.

[0307] In some embodiments of the greenhouse panel, the wavelength conversion layer or layers may be sandwiched in between glass or polymer plates, wherein the glass or polymer plates may act to protect the wavelength conversion layer or layers from moisture or oxygen penetration.

[0308] In some embodiments of the greenhouse panel, the polymer matrix of the wavelength conversion layer or layers is independently formed from a substance selected from the group consisting of polyethylene terephthalate, polymethyl methacrylate, polyvinyl butyral, ethylene vinyl acetate, ethylene tetrafluoroethylene, polyimide, amorphous polycarbonate, polystyrene, siloxane sol-gel, polyurethane, polyacrylate, and combinations thereof.

[0309] In some embodiments of the greenhouse panel, the polymer matrix of the wavelength conversion layer or layers may be made of one host polymer, a host polymer and a co-polymer, or multiple polymers.

[0310] In some embodiments, the polymer matrix material used in the wavelength conversion layer or layers has a refractive index in the range of about 1.40 to about 1.70. In some embodiments, the refractive index of the polymer matrix material used in the wavelength conversion layer is in the range of about 1.45 to about 1.55. In some embodiments, the refractive index of the polymer matrix material used in the wavelength conversion layer or layers is in the range of about 1.45 to about 1.55, from about 1.40 to about 1.50, from about 1.50 to about 1.60, or from about 1.60 to about 1.70. [0311] In some embodiments, the wavelength conversion layer comprises an optically transparent polymer matrix and at least one of chromophore (A) or chromophore (B). In some embodiments, a wavelength conversion layer can be fabricated by (i) preparing a polymer solution with dissolved polymer powder in a solvent, such as cyclopentanone, dioxane, tetrachloro ethylene (TCE), etc., at a predetermined ratio; (ii) preparing a chromophore containing a polymer mixture by mixing the polymer solution with the one or more chromophores at a predetermined weight ratio to obtain a chromophore-containing polymer solution, (iii) forming the chromophore/polymer thin film by directly casting the chromophore-containing polymer solution onto a glass substrate, then heat treating the substrate from room temperature up to 100°C in 2 hours, completely removing the remaining solvent by further vacuum heating at 130°C overnight, and (iv) peeling off the chromophore/polymer thin film under the water and then drying out the free-standing polymer film before use; (v) the film thickness can be controlled from Ο. ΐ μιη-ΐηιιη by varying the chromophore/polymer solution concentration and evaporation speed.

[0312] In some embodiments, the composition of the at least one wavelength conversion layer further comprises an antioxidant which may act to prevent additional degradation of the chromophore compounds.

[0313] In some embodiments, additional materials may be used in the greenhouse panel, such as glass plates, polymer layers, or reflective mirror layers. The materials may be used to encapsulate the wavelength conversion layer or layers, or they may be used to protect or encapsulate the wavelength conversion layer(s). In some embodiments, glass plates selected from low iron glass, borosilicate glass, or soda-lime glass, may be used in the greenhouse panel. In some embodiments, the composition of the glass plate or polymer layers may also further comprise a strong UV absorber to block harmful high energy radiation into the panel. The UV absorber in the glass plates or polymer layers may also block harmful high energy radiation from the wavelength conversion layer, thus improving the lifetime of the wavelength conversion layer(s).

[0314] A chromophore with improved lifetime is one for which the length of time it takes for 50% of the original chromophore to degrade has been increased by greater than about 50%, 100%, 200%, or 300%. For instance, if a chromophore typically degraded such that 50% of the chromophore remained after 10 days, a 100% increase in the lifetime of the chromophore would mean that the chromophore took 20 days to degrade to 50%. That degradation rate slowing would constitute an improved lifetime.

[0315] In another embodiment, the greenhouse solar collection panel comprises the greenhouse panel, as disclosed herein, and at least one solar energy conversion device. The greenhouse solar collection panel is useful as a greenhouse roof to simultaneously provide improved plant growth and solar harvesting ability which is photostable for long periods of time. In some embodiments, the at least one solar energy conversion device is encapsulated within the greenhouse solar collection panel such that the device is not exposed to the outside environment, and wherein the solar energy conversion device receives a portion of the solar energy and converts that energy into electricity.

[0316] Some embodiments provide a greenhouse solar collection panel. In some embodiments the greenhouse solar collection panel comprises at least one wavelength conversion layer, wherein the wavelength conversion layer is formed by curing a layer of the composition for forming a photostable wavelength conversion material, and at least one solar energy conversion device.

[0317] The greenhouse panel and the greenhouse solar collection panel may have numerous configurations. In some embodiments, the panel may comprise only a single wavelength conversion layer formed by curing a layer of the composition for forming a photostable wavelength conversion material. In some embodiments, multiple wavelength conversion layers may be present. Additional polymer layers or glass sheets may also be incorporated into the greenhouse panel and the greenhouse solar collection panel. Various structures for the greenhouse panel and the greenhouse solar collection panel may be similar to those shown in U.S. Provisional Patent Application No. 61/923,559, and International Application No. PCT/US2014/031722.

[0318] In some embodiments of the greenhouse panel, additional materials or layers may be used such as edge sealing tape, frame materials, polymer materials, or adhesive layers to adhere additional layers to the system. In some embodiments, the greenhouse panel further comprises an additional polymer layer containing a UV absorber. In some embodiments, the UV absorber may be selected to absorb UV wavelengths that are not absorbed by the chromophore (A). By doing this, the UV wavelengths which can be converted to useable blue light by the chromophore (A) will be converted, while the UV wavelengths that cannot be converted by chromophore (A) will be absorbed by the UV absorber, so that these harmful wavelengths do not reach the plants inside the greenhouse.

[0319] Figure 12 illustrates an embodiment of a greenhouse panel 108 comprising a first organic photostable chromophore (A) 109, and a second organic photostable chromophore (B) 1 10, wherein (A) 109 and (B) 1 10 are mixed within a wavelength conversion layer 101 , and wherein said wavelength conversion layer 100 comprises an optically transparent crosslinkable polymer and at least one crosslinking agent. In some embodiments, (A) 109 has an absorption peak maximum in the UV region of the light spectrum 1 1 1 and has an emission peak maximum in the blue region of the light spectrum 1 12. In some embodiments, (B) 1 10 has an absorption peak maximum in the green region of the light spectrum 1 13 and has an emission peak maximum in the red region of the light spectrum 1 14.

[0320] In some embodiments, the greenhouse solar collection panel comprises at least one solar energy conversion device. The greenhouse solar collection panel is useful as a greenhouse roof to simultaneously provide improved plant growth and to allow solar energy harvesting. In some embodiments, the at least one solar energy conversion device is encapsulated within the greenhouse panel such that the device is not exposed to the outside environment, and wherein the solar energy conversion device receives a portion of the solar energy and converts that energy into electricity.

[0321] One issue with incorporating luminescent materials into greenhouse roofing panels is that the incident photons, once absorbed and re-emitted by the luminescent material, often become trapped within the polymer matrix of the panel, and never reach the plant species inside the greenhouse. For greenhouse panels with luminescent materials which do not also comprise a solar cell or photovoltaic module, this trapped light is usually dissipated as heat. One advantage of incorporating solar energy conversion devices into the greenhouse roofing panels that have luminescent materials is that most of this trapped light will be absorbed by the solar energy conversion device, and converted into electricity, so that very little light is wasted.

[0322] Simultaneously, the incorporation of solar energy conversion devices into the panel provides sufficient electricity generation by converting a portion of the solar energy into electricity. Various designs can be used to incorporate solar cells into the greenhouse panel to form a greenhouse solar collection panel, depending on the electricity generation that is desired and the amount of photons that are needed to reach the plant species. When solar energy conversion devices are incorporated into greenhouse roofing panels, the solar energy conversion device competes with the plants for the incident solar radiation. The solar energy conversion device is opaque, and will block the incident solar radiation. So if too much of the greenhouse roofing panel has solar energy conversion devices incorporated, the solar energy reaching the plants inside the greenhouse may be too low. In some embodiments, the amount of solar energy conversion devices incorporated into the greenhouse solar collection panel may be tailored to meet the solar radiation requirements of the plants within the greenhouse. In some embodiments, different portions of the greenhouse may comprise different densities of solar energy conversion devices within the greenhouse solar collection panels. For instance, the north side of a greenhouse roof may incorporate more solar energy conversion devices in the greenhouse solar collection panels compared to the south side of the greenhouse. Adjustments may be made based on the location of the greenhouse.

[0323] There is no restriction on the placement of the solar energy conversion device within the greenhouse panel. In some embodiments, the solar energy conversion device may be incorporated into one of the wavelength conversion layers of the grenhouse panel. In some embodiments, the solar energy conversion device may be incorporated in between the wavelength conversion layer or layers and another polymer or glass layer of the greenhouse panel. In some embodiments, the placement of the solar energy conversion device in the greenhouse panel may be designated based on the type of solar energy conversion device. For instance, in some embodiments, the solar energy conversion devices which degrade quickly with exposure to UV radiation may be placed in the greenhouse panel such that the wavelength conversion layer comprising chromophore (A) has an absorption peak maximum in the UV region of the light spectrum and has an emission peak maximum in the blue region of the light spectrum , so that these harmful UV photons are converted to longer wavelength photons before they reach the solar energy conversion device, effectively protecting the solar energy conversion device from receiving UV radiation.

[0324] Different types of solar cells often utilize different wavelengths of photons differently. For example, some Silicon based devices are more efficient at converting higher wavelength photons into electricity, while CdTe based solar cells may be more efficient at converting photons in the orange and red spectrum into electricity. Therefore, the solar energy conversion device may also be placed within a wavelength conversion layer that re- emits radiation at the optimal wavelength for the solar energy conversion device to convert photons into electricity. For instance, silicon based solar cells which exhibit their maximum electrical conversion rates with blue photons, would be placed in the greenhouse panel at a position that would allow the silicon solar cell to capture mostly blue photons. The optimal electrical conversion rates vary with different types of solar cells. Therefore, in some embodiments, the solar energy conversion device may be placed within the greenhouse panel at a position that maximizes the capture of the optimal wavelength photons for that particular solar energy conversion device.

[0325] The greenhouse solar collection panel is compatible with all different types of solar energy conversion devices. Therefore, in some embodiments, the greenhouse solar collection panel can be constructed to be compatible with all different types and sizes of solar cells and solar panels, including Silicon based devices, III-V and II-VI PN junction devices, CIGS thin film devices, organic sensitizer devices, organic thin film devices, CdS/CdTe thin film devices, dye sensitized devices, etc. Devices, such as an amorphous Silicon solar cell, a microcrystalline Silicon solar cell, and a crystalline Silicon solar cell, can also be utilized. In some embodiments, the solar energy conversion device comprises at least one photovoltaic device or solar cell comprising a Cadmium Sulfide/Cadmium Telluride solar cell. In some embodiments, the solar energy conversion device comprises a Copper Indium Gallium Diselenide solar cell. In some embodiments, the solar energy conversion device comprises a III-V or II-VI PN junction device. In some embodiments, the solar energy conversion device comprises an organic sensitizer device. In some embodiments, the solar energy conversion device comprises an organic thin film device. In some embodiments, the solar energy conversion device comprises an amorphous Silicon (a-Si) solar cell. In some embodiments, the solar energy conversion device comprises a microcrystalline Silicon ^c-Si) solar cell. In some embodiments, the solar energy conversion device comprises a crystalline Silicon (c-Si) solar cell.

[0326] In some embodiments of the greenhouse solar collection panel, multiple types of photovoltaic devices may be used within the panel and may be independently selected and incorporated into the greenhouse panel according to the emission wavelength of the wavelength conversion layer, to provide the highest possible photoelectric conversion efficiency. Additionally, a mixture of chromophores in the wavelength conversion layer may be selected such that the emission spectrum of the wavelength conversion layer is optimized for a particular photovoltaic or solar cell device, provided that the light reaching the plants inside the greenhouse comprises blue and red wavelengths.

[0327] In some embodiments, the greenhouse solar collection panel further comprises a refractive index matching liquid that is used to attach the layers within the greenhouse panel to the light incident surface of the photovoltaic device or solar cell. In some embodiments the refractive index matching liquid used is a Series A mineral oil comprising aliphatic and alicyclic hydrocarbons, and hydrogenated terphenyl from Cargille- Sacher Labratories, Inc.

[0328] In some embodiments, as shown in Figure 12, the re-emitted photons may become trapped by internal reflection 151 within the greenhouse panel. This internally reflected portion of the spectrum can be harvested in a photovoltaic device to produce useable electricity.

[0329] Figure 13 illustrates an embodiment of a greenhouse panel 108 comprising a first organic photostable chromophore (A) 109, and a second organic photostable chromophore (B) 1 10, wherein (A) 109 is located in a first wavelength conversion layer 10Γ and (B) 1 10 is located in a second wavelength conversion layer 101". In some embodiments, not pictured, (B) 1 10 is located in the first wavelength conversion layer 101 ' and (A) 109 is located in the second wavelength conversion layer 101". In some embodiments, each wavelength conversion layer independently comprises an optically transparent crosslinkable polymer and at least one crosslinking agent. In some embodiments, (A) 109 has an absorption peak maximum in the UV region of the light spectrum 1 1 1 and has an emission peak maximum in the blue region of the light spectrum 1 12 and (B) 1 10 has an absorption peak maximum in the green region of the light spectrum 1 13 and has an emission peak maximum in the red region of the light spectrum 1 14. In some embodiments, the re-emitted photons may become trapped by internal reflection 1 15 and are transported to a solar cell.

[0330] In some embodiments, the greenhouse panel 108 further comprises one or more adhesive layers. In some embodiments, the one or more adhesive layers adhere the wavelength conversion layer or layers together. In some embodiments, the adhesive film may adhere the solar energy conversion device to any of the various layers within the greenhouse panel. Various types of adhesives may be used. In some embodiments, the adhesive layer or layers independently comprises a substance selected from the group consisting of rubber, acrylic, silicone, vinyl alkyl ether, polyester, polyamide, urethane, fluorine, epoxy, ethylene vinyl acetate, and combinations thereof. The adhesive can be permanent or non-permanent. In some embodiments, the thickness of the adhesive layer is between about 1 μηι and 100 μηι. In some embodiments, the refractive index of the adhesive layer is in the range of about 1.40 to about 1.70.

[0331] Figure 14 illustrates an embodiment of a greenhouse panel 108 comprising a first organic photostable chromophore (A) 109 is located in a first wavelength conversion layer 101 ' and (B) 1 10 is located in a second wavelength conversion layer 101 " and further comprising a glass or polymer plate 1 16. As discussed above, these layers 101 ', 101 ", 1 16 may be adhered to one another using adhesive layers. Also, as above, each of said wavelength conversion layers 101 ', 101 " may independently comprise an optically transparent crosslinkable polymer and at least one crosslinking agent wherein (A) 109 has an absorption peak maximum in the UV region of the light spectrum 1 1 1 and has an emission peak maximum in the blue region of the light spectrum 1 12, and wherein (B) 1 10 has an absorption peak maximum in the green region of the light spectrum 1 13 and has an emission peak maximum in the red region of the light spectrum 1 14 . In some embodiments, the re- emitted photons may become trapped by internal reflection 1 15 within the luminescent panel. This internally reflected portion of the spectrum can be harvested in a photovoltaic device to produce useable electricity. The glass or polymer plate 1 16 can be used to increase the efficiency of reflection and refraction within the greenhouse panel 108 to increase the amount of light harvested by the photovoltaic.

[0332] Other layers may also be included to further enhance the photoelectric conversion efficiency of the greenhouse panel. For example, the greenhouse solar collection panel may additionally have at least one microstructured layer, which is designed to further enhance the solar harvesting efficiency of solar modules by decreasing the loss of photons to the environment (see U.S. Provisional Patent Application No. 61/555,799). A layer with various microstructures on the surface (i.e. pyramids or cones) may increase internal reflection and refraction of the photons into the photoelectric conversion layer of the solar cell, further enhancing the solar harvesting efficiency of the device. As above, these layers may be adhered to each other using an adhesive layer.

[0333] Figure 15 illustrates an embodiment of a greenhouse solar collection panel comprising a greenhouse panel 10 and at least one solar energy conversion device 100. The greenhouse panel comprises a first organic photostable chromophore (A) 109 is located in a first wavelength conversion layer 101 ' and (B) 1 10 is located in a second wavelength conversion layer 101 ". In some embodiments, each of the wavelength conversion layers 10Γ, 101" independently further comprises an optically transparent crosslinkable polymer and at least one crosslinking agent, and wherein (A) 109 has an absorption peak maximum in the UV region of the light spectrum 1 1 1 and has an emission peak maximum in the blue region of the light spectrum 1 12, and wherein (B) 1 10 has an absorption peak maximum in the green region of the light spectrum 1 13 and has an emission peak maximum in the red region of the light spectrum 1 14. In some embodiments, the re-emitted photons may become trapped by internal reflection 1 15 within the greenhouse panel, wherein these trapped photons may be absorbed by the solar energy conversion device 100. In some embodiments, the greenhouse panel further comprises glass or polymer plates 1 16.

[0334] Solar energy conversion devices utilizing different types of light incident surfaces may be used. For instance, some solar energy conversion devices are dual sided, and may receive radiation from two sides. Some solar energy conversion devices may only receive radiation on one side. In some embodiments of the greenhouse solar collection panel, a dual sided solar energy conversion device is used such that it may receive direct incident solar radiation on one of its sides, and it may also receive indirect radiation from internal reflection within the greenhouse panel on two of its sides. In some embodiments of the greenhouse solar collection panel, a single sided solar energy conversion device is used and is positioned within the greenhouse solar collection panel such that it receives direct incident solar radiation on its one side, and may also receive indirect radiation from internal reflection within the greenhouse panel on its one side. It may be desirable to position the solar energy conversion device upside down, such that the light incident side of the solar energy conversion device is facing away from the sun. When the solar energy conversion device is upside down, it cannot receive direct solar radiation, which limits the radiation that will be converted into energy to that of the photons which become trapped within the greenhouse panel and are internally reflected and refracted until they reach the solar energy conversion device. This helps to alleviate the competition between the plants and the solar cells. It also protects the solar cells from direct sunlight, which may increase their lifetime by decreasing the amount of UV radiation exposure. Therefore, in some embodiments of the greenhouse solar collection panel, a single sided solar energy conversion device is used and is positioned within the greenhouse solar collection panel such that it cannot receive direct incident solar radiation on its one side, and may only receive indirect radiation from internal reflection within the greenhouse panel on its one side.

[0335] For purposes of summarizing aspects of the invention and the advantages achieved over the related art, certain objects and advantages of the invention are described in this disclosure. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

[0336] Further aspects, features and advantages of this invention will become apparent from the detailed examples which follow.

EXAMPLES

[0337] The embodiments will be explained with respect to certain embodiments which are not intended to limit the present invention. Further, in the present disclosure where conditions and/or structures are not specified, the skilled artisan in the art can readily provide such conditions and/or structures, in light of the teachings herein, as a matter of routine experimentation.

Synthesis of Chromophores

Compound 1

[0338] Common Intermediate A was synthesized according to the following scheme.

Step 1 : 2-Isobutyl-2H-benzo[J|[l ,2,31triazole.

[0339] A mixture of benzotriazole (1 1.91 g, 100 mmol), l -iodo-2-methylpropane (13.8 mL, 120 mmol), potassium carbonate (41.46 g, 300 mmol), and dimethylformamide (200 mL) was stirred and heated under argon at 40°C for 2 days. The reaction mixture was poured into ice/water (1 L) and extracted with toluene/hexanes (2: 1 , 2 x 500 mL). The extract was washed with 1 N HQ (2 x 200 mL) followed by brine (100 mL), dried over anhydrous magnesium sulfate, and the solvent was removed under reduced pressure. The residue was triturated with hexane (200 mL) and set aside at room temperature for 2 hours. The precipitate was separated and discarded, and the solution was filtered through a layer of silica gel (200 g). The silica gel was washed with hexane/dichloromethane/ethyl acetate (37:50:3, 2 L). The filtrate and washings were combined, and the solvent was removed under reduced pressure to give 2-isobutyl-2H-benzo[JJ[l ,2,3]triazole (8.81 g, 50% yield) as an oily product. 1H NMR (400 MHz, CDC1₃): δ 7.86 (m, 2H, benzotriazole), 7.37 (m, 2H, benzotriazole), 4.53 (d, J = 7.3 Hz, 2H, z-Bu), 2.52 (m, 1H, i-Bu), 0.97 (d, J = 7.0 Hz, 6H, i- Bu).

Step 2: 4,7-Dibromo-2-isobutyl-2H-benzo[J||T ,2,31triazole (Intermediate A).

[0340] A mixture of 2-isobutyl-2H-benzo[J][l ,2,3]triazole (8.80 g, 50 mmol), bromine (7.7 mL, 150 mmol) and 48% HBr (50 mL) was heated at 130°C for 24 hours under a reflux condenser connected with an HBr trap. The reaction mixture was poured into ice/water (200 mL), treated with 5 N NaOH (100 mL) and extracted with dichloromethane (2 x 200 mL). The extract was dried over anhydrous magnesium sulfate, and the solvent was removed under reduced pressure. A solution of the residue in hexane/dichloromethane (1 : 1 , 200 mL) was filtered through a layer of silica gel and concentrated to give 4,7-dibromo-2- isobutyl-2H-benzo[JJ[l ,2,3]triazole, Intermediate A (1 1.14 g, 63% yield) as an oil that slowly solidified upon storage at room temperature. 1H NMR (400 MHz, CDC1₃): δ 7.44 (s, 2H, benzotriazole), 4.58 (d, J = 7.3 Hz, 2H, z-Bu), 2.58 (m, 1H, z-Bu), 0.98 (d, J = 6.6 Hz, 6H, z-Bu).

Compound 1

[0341] Example Chromophore Compound 1 was synthesized according to the following reaction scheme.

4-/-BuOC₆H₄B(OH)₂

A 1

[0342] A mixture of Intermediate A (1.32 g, 4.0 mmol), 4- isobutoxyphenylboronic acid (1.94 g, 10.0 mmol), tetrakis(triphenylphosphine)palladium(0) (1.00 g, 0.86 mmol), solution of sodium carbonate (2.12 g, 20 mmol) in water (15 mL), butanol (50 mL), and toluene (30 mL) was vigorously stirred and heated under argon at 100°C for 16 hours. The reaction mixture was poured into water (300 mL), stirred for 30 minutes and extracted with toluene/ethyl acetate/hexane (5:3:2, 500 mL). The volatiles were removed under reduced pressure, and the residue was chromatographed (silica gel, hexane/dichloromethane, 1 : 1). The separated product was recrystallized from ethanol to give pure 4,7-bis(4-isobutoxyphenyl)-2-isobutyl-2H-benzo[JJ[l,2,3]triazole, Compound 1 (1.57 g, 83% yield). ^!H NMR (400 MHz, CDC1₃): δ 7.99 (d, J = 8.7 Hz, 4H, 4-z-BuOC₆H₄), 7.55 (s, 2H, benzotriazole), 7.04 (d, J = 8.8 Hz, 4H, 4-z-BuOC₆H₄), 4.58 (d, J = 7.3 Hz, 2H, z-Bu), 3.79 (d, J = 6.6 Hz, 4H, 4-z-BuOC₆H₄), 2.59 (m, 1H, i-Bu), 2.13 (m, 2H, 4-z-BuOC₆H₄), 1.04 (d, J = 6.6 Hz, 12H, 4-z-BuOC₆H₄), 1.00 (d, J = 6.6 Hz, 6H, i-Bu). UV-vis spectrum (PVB): η_ιαχ = 359 nm. Fluorimetry (PVB): _max = 434 nm.

Compound 2

[0343] Example Chromophore Compound 2 was synthesized according to the following reaction scheme.

C 2

[0344] A mixture of Intermediate A (3.00 g, 8.6 mmol), the boronic acid (4.44 g, 20 mmol), potassium carbonate (5.52 g, 40 mmol), tetrakis(triphenylphosphine)palladium(0) (2.00 g), n-butanol (60 mL), toluene (20 mL), and water (10 mL) was stirred under argon and heated at 100°C for 4 hours. The reaction mixture was poured into water (300 mL) and extracted with ethyl acetate/toluene (2: 1 , 2 x 300 mL). The extract was dried over sodium sulfate, the volatiles were removed under reduced pressure. The crude product obtained was purified by column chromatography (silica gel - hexane/dichloromethane/ethyl acetate, 37:60:3) and recrystallization from ethanol to give Intermediate B (3.76 g, 83% yield).

[0345] Then, a mixture of Intermediate B (2.80 g, 5.3 mmol), montmorillonite K 10 (1.00 g), methanol (25 mL), and dichloromethane (25 mL) was stirred under argon and heated at 40°C for 1 hours. TLC showed no starting material left. The solid was filtered off, and the solvent was removed under reduced pressure to give Intermediate C (2.12 g) that is insoluble in dichloromethane and chloroform, but well soluble in acetone.

[0346] Then, a mixture of Intermediate C (400 mg, 1.1 mmol), 2-ethyl-l- bromoburtane (0.9 mL, 6.4 mmol), potassium carbonate (1.0 g, 7.2 mmol), and dimethylformamide (20 mL) was stirred under argon and heated at 120°C for 20 hours. The reaction mixture was poured into water ((200 mL) and extracted with 200 mL of toluene/petroleum ether (b. p. 80-100°C). The volatiles were removed under reduced pressure; the residue was dried in a vacuum oven and subjected to column chromatography. The obtained material was recrystallized from acetonitrile to give pure Chromophore Compound 2 (4,7-bis(4-(2-ethylbutoxy)phenyl)-2-isobutyl-2H-benzo[d][l,2,3]triazole) (434 mg, 75% yield). 1H NMR (400 MHz, CDC1₃): 5 7.99 (d, J = 8.8 Hz, 4H, 4- Et₂CHCH₂OC₆H₄), 7.54 (s, 2H, benzotriazole), 7.04 (d, J = 8.8 Hz, 4H, 4-Et₂CHCH₂OC₆H₄), 4.58 (d, J = 7.3 Hz, 2H, z-Bu), 3.92 (d, J = 5.8 Hz, 4H, 4-Et₂CHCH₂OC₆H₄), 2.59 (m, 1H, i- Bu), 1.71 (m, 2H, 4-Et₂CHCH₂OC₆H₄), 1.50 (m, 8H, 4-Et₂CHCH₂OC₆H₄), 1.00 (d, J = 6.6 Hz, 6H, z-Bu), 0.94 (t, J = 7.1 Hz, 12H, 4-Et₂CHCH₂OC₆H₄. UV-vis spectrum (PVB): _max = 358 nm. Fluorimetry (PVB): _max = 433 nm.

Compound 3

[0347] Example Chromophore Compound 3 was synthesized according to the following reaction scheme.

D 3

[0348] 2,2 dimethyl- 1 -propanol (21.89 g, 248.4 mmol) was added to a stirred mixture of 4-toluenesulfonyl chloride (49.72 g, 260.82 mmol) in dichloromethane (520 mL) followed by Et₃N (35.1 1 mL, 260.82 mmol). The resultant mixture was stirred at room temperature for 16 hours. The reaction mixture was poured into water (350 mL); the organic layer was washed with IM a₂C0₃ (2 x 300 mL), dried over Na₂SC>4 and concentrated to give 43 g of sticky oily product. NMR showed that the obtained neopentyl tosylate contained 10% of starting 4-toluenesulfonyl chloride, and it was used for next step without further purification. Yield: 68%. [0349] Then, potassium carbonate (51.6 g, 300 mmol) was added to a stirred mixture of neopentyl tosylate (90% pure) (26.92 g, 100 mmol) and benzotriazole ( 17.86 g, 260.82 mmol) in dimethylformamide (200 mL). The resultant mixture was stirred at 80°C for 3 days under nitrogen. The reaction mixture was poured into water (300 mL) and extracted with dichloromethane (2 x 350 mL). The extract was washed with water (250 mL) and concentrated under reduced pressure. Column chromatography of the residue using silica gel and hexane/ethyl acetate (9: 1) as an eluent gave 7.28 g of 2-neopentyl-2H- benzo[d][l ,2,3]triazole as a light brown oil. Yield: 38.5 %.

[0350] Bromine (4.31 mL, 84.27 mmol) was added drop-wise to a stirred mixture of 2-neopentyl-2H-benzo[d][l ,2,3]triazole (7.25 g, 38.3 mmol) in 48% HBr (58 mL) at room temperature. The resultant mixture was stirred at 130°C for 16 hours. Another portion of bromine (1 mL) was added, and stirring at 130°C was continued for an additional 3 hours. The reaction mixture was poured into ice/water (500 mL), stirred for 15 min and extracted with dichloromethane (2 x 400 mL). The extract was washed with brine (250 mL), dried over Na₂S0₄, and the solvent was removed under reduced pressure to give crude Intermediate D (10.98 g, 82% yield) as a dark-color oil, which turned into solid after standing at room temperature overnight. Crude Intermediate D was used in the next step without purification.

[0351] A mixture of Intermediate D (694 mg, 2.0 mmol), 4- isobutoxyphenylboronic acid (970 mg, 5.0 mmol), potassium carbonate (1.38 g, 10 mmol), n- butanol (40 mL), water (3 mL), toluene (15 mL), and Pd(PPh₃)₄ (0.50 g) was stirred under argon and heated at 100°C for 16 hours. After cooling, the reaction mixture was poured into ice/water (200 mL), stirred for 15 min and extracted with toluene/ethyl acetate (1 : 1 , 300 mL). The extract was dried over MgS0₄, and the volatiles were removed under reduced pressure. The crude product was purified by column chromatography (silica gel, hexane/dichloromethane, 1 : 1) and recrystallization from ethanol to give Chromophore Compound 3 (4,7-bis(4-isobutoxyphenyl)-2-neopentyl-2H-benzo[d][l ,2,3]triazole) (680 mg, 70% yield) as colorless needles. 1H NMR (400 MHz, CDC1₃): δ 8.00 (d, J = 8.8 Hz, 4H, 4- z-BuOC₆H₄), 7.55 (s, 2H, benzotriazole), 7.03 (d, J = 8.8 Hz, 4H, 4-z-BuOC₆H₄), 4.58 (d, J = 7.3 Hz, 2H, neopentyl), 3.79 (d, J = 6.6 Hz, 4H, 4-z-BuOC₆H₄), 2.1 1 (m, 2H, 4-z-BuOC₆H₄), 1.10 (s, 9H, neopentyl), 1.04 (d, J = 6.7 Hz, 12H, 4-z-BuOC₆H₄). UV-vis spectrum (PVB): η_ιαχ = 360 nm. Fluorimetry (PVB): _max = 435 nm.

Intermediate E

[0352] Common Intermediate E is synthesized in a two step process.

Step 1 : Synthesis of 2-(4-Nitrophenyl)-2H-benzo[JJ[l,2,3]triazole.

[0353] A mixture of 4-chloronitrobenzene (55.0 g, 349 mmol), benzotriazole (50.0 g, 420 mmol), potassium carbonate (200 g, 500 mmol), and MP (500 mL) was stirred and heated under argon at 130°C for 5 hours. Progress of the reaction was monitored by thin layer chromatography. The reaction mixture was poured onto crushed ice (2 kg). After all ice melted, the solid was filtered off and washed with water (200 mL). The product was suspended in methanol (1.5 L) and stirred for 30 minutes. The crystals were filtered off and dried in a vacuum oven. Column chromatography of the obtained material using silica gel and hot solution of ethyl acetate (1%) in toluene as an eluent gave 2-(4-nitrophenyl)-2H- benzo[JJ[l,2,3]triazole (24.24 g, 30% yield). 1H NMR (400 MHz, CDC1₃): δ 8.57 (d, J = 9.2 Hz, 2H, 4-nitrophenyl), 8.44 (d, J = 9.2 Hz, 2H, 4-nitrophenyl), 7.93 (m, 2H, benzotriazole), 7.47 (m, 2H, benzotriazole).

Step 2: Synthesis of 4,7-Dibromo-2-(4-nitrophenyl)-2H-benzo[J][l,2,3]triazole (Intermediate E).

[0354] A mixture of 2-(4-nitrophenyl)-2H-benzo[J][l,2,3]triazole (7.70 g, 31.2 mmol), bromine (4.8 mL, 94 mmol) and 48% HBr (120 mL) was heated at 130°C for 20 hours under a reflux condenser connected with an HBr trap. The reaction mixture was poured onto crushed ice (800 g), decolorized with 5% solution of Na₂S0₃, and set aside at room temperature for 2 hours. The precipitate was filtered off, washed with water (200 mL) followed by 2% NaHC0₃ (200 mL) and again water (200 mL). The material was dried in a vacuum oven to give 4,7-dibromo-2-(4-nitrophenyl)-2H-benzo[JJ[l ,2,3]triazole (Intermediate E, 13.47 g) of purity 90%. Yield 97%. 1H NMR (400 MHz, CDC1₃): δ 8.65 (m, 2H, 4-nitrophenyl), 8.44 (m, 2H, 4-nitrophenyl), 7.54 (s, 2H, benzotriazole).

Intermediate F

[0355] Intermediate F was synthesized using the following reaction scheme.

[0356] A mixture of Intermediate E (3.98 g, 10.0 mmol), 4- isobutoxyphenylboronic acid (5.00 g, 25.7 mmol), sodium carbonate (5.30 g, 50 mmol) in water (40 mL), tetrakis(triphenylphosphine)palladium(0) (2.00 g), «-butanol (60 mL), and toluene (30 mL) was stirred under argon and heated at 100°C for 4 hours. The reaction mixture was poured into water (200 mL), stirred for 30 minutes and extracted with toluene (500 mL). The extract was washed with water (200 mL), concentrated to a volume of 100 mL and diluted with dichloromethane (200 mL) and methanol (200 mL). The obtained solution was hydrogenated for 20 minutes at 50 psi over 10% Pd/C (2 g), filtered through a layer of Celite, and the solvent was removed under reduced pressure. The residue was chromatographed (silica gel, hexane/dichloromethane/ethyl acetate, 35:50:5) to give 4,7- Bis(4-isobutoxyphenyl)-2-(4-aminophenyl)-2H-benzo[J][l ,2,3]triazole (Intermediate F) (3.80 g, 75%). 1H NMR (400 MHz, CDC1₃): δ 8.22 (d, J = 8.4 Hz, 2H, 4-aminophenyl), 8.09 (d, J = 8.7 Hz, 4H, 4-z-BuOC₆H₄), 7.57 (s, 2H, benzotriazole), 7.06 (d, J = 8.7 Hz, 4H, 4-z- BuOC₆H₄), 6.79 (d, J = 8.5 Hz, 2H, 4-aminophenyl), 3.90 (bs, 2H, NH₂), 3.81 (d, J = 6.6 Hz, 4H, j-BuO), 2.14 (m, 2H, z-BuO), 1.06 (d, J = 7.0 Hz, 12H, z-BuO).

Compound 4

[0357] Chromophore Compound 4 was synthesized according to the following reaction scheme.

[0358] A solution of Intermediate F (0.92 g, 1.82 mmol), 3,3-dimethylglutaric anhydride (284 mg, 2.0 mmol) in 1,2-dichloroethane (20 mL) was heated under a reflux condenser at 80°C for 20 hours. After cooling to room temperature, acetyl chloride (0.28 mL, 4.0 mmol) was added, and the mixture was heated at 80°C for 1 hour. The reaction mixture was diluted with dichloromethane (200 mL) and washed with saturated NaHC0₃ (100 mL). The solution was dried over MgS0₄, and the volatiles were removed under reduced pressure. The crude product was purified by column chromatography (silica gel, hexane/dichloromethane/ethyl acetate, 37:60:3) and crystallization from ethanol to give l-(4- (4,7-bis(4-isobutoxyphenyl)-2H-benzo[JJ[l,2,3]triazol-2-yl)phenyl)-4,4-dimethylpiperidine- 2,6-dione (Compound 4, 551 mg, 48% yield) as thin yellow needles. 1H NMR (400 MHz, CDC1₃): δ 8.53 (d, J = 8.8 Hz, 2H, 4-imidophenyl), 8.08 (d, J = 8.8 Hz, 4H, 4-z-BuOC₆H₄), 7.61 (s, 2H, benzotriazole), 7.26 (d, J = 8.8 Hz, 2H, 4-imidophenyl), 7.07 (d, J = 8.8 Hz, 4H, 4-z-BuOC₆H₄), 3.82 (d, J = 6.6 Hz, 4H, z-BuO), 2.72 (s, 4H, 4,4-dimethylpiperidine-2,6- dione), 2.14 (m, 2H, z^'-BuO), 1.24 (s, 6H, 4,4-dimethylpiperidine-2,6-dione), 1.06 (d, J = 7.0 Hz, 12H, z-BuO). UV-vis spectrum (PVB): _max = 388 nm. Fluorimetry (PVB): _max = 478 nm. Optically Transparent Crosslinkable Polymer Material

[0359] Ethylene vinyl acetate copolymer (EVA) was obtained from Dupont (Dupont Elvax product PV1400Z) or Arkema and used as received. In some embodiments, the vinyl acetate content in the EVA is in the range of 20 to 45 parts by weight, and, in some embodiments, in the range of 28 to 33 parts by weight, based on 100 parts by weight of EVA. For the Example Compositions 1- 12 below, the vinyl acetate content in the EVA is 32 parts by weight, based on 100 parts by weight of EVA.

Adhesion promoter

[0360] As the adhesion promoter, a silane coupling agent 3- methacryloxypropyltrimethoxysilane (KBM-503) was obtained from ShinEtsu and used as received.

Stabilizer

[0361] The stabilizer Bis(l ,2,2,6,6-pentamethyl-4-piperidinyl)-[[3,5-bis(l ,l- dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate (Tinuvin 144) was obtained from BASF and used as received.

Crosslinker

[0362] The crosslinker ethylene glycol dimethacrylate (EGDMA), trimethylolpropane trimethacrylate (TMPTMA), and triallyl isocyanuate (TAIC), were purchased from Aldrich and used as received.

Crosslinking reagent

[0363] The organic peroxides t-butylperoxy-2ethylhexylmonocarbonate (Perbutyl E), l ,l -di(t-butylperoxy)cyclohexane (Perhexa C), and 2,5-dimethyl-2,5-di(t- butykperoxy)hexane (Perhexa 25B), were used as crosslinking reagents, and were obtained from NOF Co. and used as received.

[0364] The present invention will now be explained with respect to the following examples, which are described for illustrative purposes only and are not intended to limit the scope of the present invention. Example 1 - Preparation of Waylength Conversion Layer

[0365] A wavelength conversion composition testing sample was prepared. The components of the composition were as follows:

[0366] To prepare the composition, a wavelength conversion layer comprising the components listed above was fabricated into a film structure following the wet processing procedure. The wavelength conversion layer is fabricated by (i) preparing a polymer solution by dissolving the EVA polymer powder or pellets in a soluble solvent such as cyclopentanone or toluene, at a predetermined ratio; (ii) preparing a chromophore solution by dissolving the chromophore in the same solvent as the polymer solution at the predetermined concentration; (iii) preparing a stabilizer solution by dissolving a stabilizer in the same solvent as the polymer solution at the predetermined concentration; (iv) preparing a wavelength conversion (WLC) solution by mixing the polymer solution with the chromophore solution and the stabilizer solution, and then adding the adhesion promoter, the coagent(s), and the peroxide (crosslinking reagent), independently and at the predetermined weight ratio; and (v) forming the wavelength conversion layer by directly casting the wavelength conversion solution onto a non-stick PTFE dish, then drying the WLC solution at room temperature for at least 24 hours and further drying the mixture under vacuum at 50-70 °C for 3~6 hours, completely removing the remaining solvent by further vacuum hot pressing at 80-100°C for 5-10min to a thickness of 200~300μηι. The wavelength conversion film was then laminated between two pieces of clear low-iron glass that were 2mm thick and approximately 5cm x 5 cm in dimension. Following lamination, the testing device was then cured to induce crosslinking. The curing temperature for the Example 1 testing device was 160°C with a curing time of 15 minutes.

Measurement of the photostability

[0367] An indoor Weatherometer chamber model Suntest XXL+ from Atlas, was used to provide accelerated radiation aging of the test samples. The weatherometer conditions were as follows: UV exposure of 60W/m² at 63°C and 60% relative humidity. For each testing sample, the absorption of the film was measured and used to determine the degradation of the chromophore within the layer. The absorption of the wavelength conversion films were measured using a UV-Vis-NIR Spectrophotometer model UV-3600 from Shimadzu. For each example composition, the absorption was measured after various irradiation exposure times in the Suntest chamber, and the normalized absorption was calculated to determine the photostability of the composition.

[0368] Figure 16 shows the normalized absorption of the Example 1 testing device after 5000 hours of exposure time.

Example 2

[0369] An Example 2 testing sample is synthesized using the same method as given in Example 1 , except the wavelength conversion composition was as follows:

[0370] Figure 17 shows the normalized absorption of the Example 2 testing device after 3500 hours of exposure time. Example 3

[0371] An Example 3 testing sample is synthesized using the same method as given in Example 1, except that the composition was crosslinked at 140°C for 35min, and the wavelength conversion composition was as follows:

[0372] Figure 18 shows the normalized absorption of the Example 3 testing device after 1500 hours of exposure time.

Example 4

[0373] Example 4 testing sample is synthesized using the same method as given in Example 3, except that the composition was crosslinked at 155°C for lOmin.

[0374] Figure 18 shows the normalized absorption of the Example 4 testing device after 1500 hours of exposure time.

Example 5

[0375] An Example 5 testing sample is synthesized using the same method as given in Example 3, except that the composition was crosslinked at 145°C for 25min.

[0376] Figure 18 shows the normalized absorption of the Example 5 testing device after 1500 hours of exposure time.

Example 6

[0377] An Example 6 testing sample is synthesized using the same method as given in Example 1, except that the composition was crosslinked at 155°C for 45min, and the wavelength conversion composition was as follows: Component Concentration (parts by weight)

(i) EVA: 100

(ii) Chromophore 1 : 0.2

(iii) KBM-503 0.1

(iv) Tinuvin 144 0.1

(v) TMPTMA 3

(vi) Perhexa 25B 0.3

[0378] Figure 19 shows the normalized absorption of the Example 6 testing device after 1500 hours of exposure time.

Example 7

[0379] An Example 7 testing sample is synthesized using the same method as given in Example 6, except that the composition was crosslinked at 155°C for 105min.

[0380] Figure 19 shows the normalized absorption of the Example 7 testing device after 1500 hours of exposure time.

Example 8

[0381] An Example 8 testing sample is synthesized using the same method as given in Example 6, except that the composition was crosslinked at 160oC for 65min.

[0382] Figure 19 shows the normalized absorption of the Example 8 testing device after 1500 hours of exposure time.

Example 9

[0383] An Example 9 testing sample is synthesized using the same method as given in Example 1 , except the wavelength conversion composition was as follows: Component Concentration (parts by weight)

(i) EVA: 100

(ii) Chromophore 1 : 0.2

(iii) KBM-503 0.1

(iv) Tinuvin 144 0.3

(v) TMPTMA 3

(vi) Pertbutyl E 0.3

[0384] Figure 20 shows the normalized absorption of the Example 9 testing device after 1000 hours of exposure time.

Example 10

[0385] An Example 10 testing sample is synthesized using the same method as given in Example 1 , except the wavelength conversion composition was as follows:

[0386] Figure 21 shows the normalized absorption of the Example 10 testing device after 1250 hours of exposure time.

Example 11

[0387] An Example 1 1 testing sample is synthesized using the same method as given in Example 10, except the wavelength conversion composition was as follows: Component Concentration (parts by weight)

(i) EVA: 100

(ii) Chromophore 2: 0.2

(iii) KBM-503 0.1

(iv) Tinuvin 144 0.1

(v) TMPTMA 3

(vi) Pertbutyl E 0.3

[0388] Figure 21 shows the normalized absorption of the Example 1 1 testing device after 1250 hours of exposure time.

Example 12

[0389] An Example 12 testing sample is synthesized using the same method as given in Example 10, except the wavelength conversion composition was as follows:

[0390] Figure 21 shows the normalized absorption of the Example 12 testing device after 1250 hours of exposure time.

Example 13

[0391] Example 13 testing sample is synthesized using the same method as given in Example 1 , except the wavelength conversion composition does not contain a stabilizer. The composition was as follows: Component Concentration (parts by weight)

(i) EVA: 100

(ii) Chromophore 4: 0.2

(iii) KBM-503 0.1

(iv) TAIC 3

(v) EGDMA 2

(vi) Perbutyl E 0.5

[0392] Figure 22 shows the normalized absorption of the Example 13 testing device after 3000 hours of exposure time.

Example 14

[0393] Example 14 testing sample is synthesized using the same method as given in Example 1 , except the wavelength conversion composition did not contain any additional additives. The composition was as follows:

[0394] Figure 22 shows the normalized absorption of the Comparative Example 14 testing device after 3000 hours of exposure time.

[0395] Table 1 below compares the compositions of the films for each of the Examples 1-14. Table 2 below compares the curing conditions for each of the Examples 1- 14.

Table 1 Comparison of Compositions of the Examples 1-14 devices in parts by weight

(pbw).

Table 2 Comparison of Curing Conditions of the Examples 1-14 devices.

[0396] The data shown in Figure 12 clearly indicates the Example 1 wavelength conversion composition has very high photostability, with hardly any degradation of the chromophore in the layer, as indicated by the very little change in the normalized absorption of the film after 5000 hours of exposure time. Additionally, all other devices showed good photostability, as indicated by the data in Figures 16-22, with less than 10% degradation of the normalized absorption after 1000 hours of exposure time. Figure 22 shows the photostability data of the Example 13 and Example 14 devices. As seen in Figure 22, clearly indicates the addition of additives significantly improves the photostability of the devices. In general, the photostability of the compositions were similar even with variations in the curing temperature and curing time, while the components in the compositions, and concentrations of the components in the compositions had a much larger effect on the photostability. Therefore, the concentration of the individual components in the WLC compositions must be adjusted to provide the desired properties for the particular application and also to yield the maximum photostability. [0397] The Example 1 sample showed very little change in the absorbance after 5000 hrs (-30 weeks) of exposure, indicating that the Example 1 composition does not yellow, and is stable. Therefore, the Example 1 composition shows that the chromophore in the film is stable to provide wavelength conversion, and the polymer material formulation is stable to provide clear transmittance of photons without yellowing, for long periods of time, and therefore would be very useful in enhancing the solar harvesting efficiency of solar energy devices.

[0398] The object of this current invention is to provide a wavelength conversion composition that is photostable for long periods of time with exposure to solar radiation. The composition may be useful to encapsulate solar energy conversion devices and/or as a greenhouse roofing material. As illustrated by the above examples, the composition is very stable after exposure to solar radiation for long periods of time. Therefore, the use of this composition to encapsulate solar cells, solar modules, photovoltaic devices, or entire solar panels, will provide stable enhancement of the photoelectric conversion efficiency for the lifetime of the solar energy harvesting device. Also, the use of this composition may provide enhanced plant growth when used as a greenhouse roofing material.

[0399] For purposes of summarizing aspects of the invention and the advantages achieved over the related art, certain objects and advantages of the invention are described in this disclosure. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein. It will be understood by those of skill in the art that numerous and various modifications can be made without departing from the spirit of the present invention. Therefore, it should be clearly understood that the forms of the present invention are illustrative only and are not intended to limit the scope of the present invention.

Claims

WHAT IS CLAIMED IS:

1. A composition for forming a photostable wavelength conversion material comprising:

a first organic chromophore;

a first optically transparent crosslinkable polymer; and

a first crosslinking reagent.

2. The composition of Claim 1, wherein the first crosslinking reagent comprises an organic peroxide.

3. The composition of Claim 2, wherein the organic peroxide is selected from the group consisting of diacyl peroxides, dialkyl peroxides, diperoxyketals, hydroperoxides, ketoneperoxides, peroxydicarbonates, and peroxyesters.

4. The composition of Claim 1 , wherein the first crosslinking reagent is selected from the group consisting of Perbutyl E, Perhexa HC, Perhexa 25B, Percumyl D, Perhexa C, Perhexa V, and Perbutyl P.

5. The composition of any one of Claims 1 to 4, wherein the first crosslinking reagent is present in an amount in the range of about 0.1% to about 2.0% by weight of the composition

6. The composition of any one of Claims 1 to 5, wherein the composition further comprises a second crosslinking reagent.

7. The composition of Claim 6, wherein the second crosslinking agent is selected from the group consisting of Perbutyl E, Perhexa HC, Perhexa 25B, Percumyl D, Perhexa C, Perhexa V, and Perbutyl P.

8. The composition of any one of Claims 1 to 7, wherein the first optically transparent crosslinkable polymer is selected from the group consisting of Ionomer, thermoplastic polyurethane, thermoplastic polyolefin, polymethyl methacrylate, polyvinyl butyral, polydimethyl silicon, ethylene-methyl methacrylate, and ethylene vinyl acetate.

9. The composition of any one of Claims 1 to 8, wherein the composition comprises a second optically transparent crosslinkable polymer.

10. The composition of Claim 9, wherein the second optically transparent crosslinkable polymer is selected from the group consisting of Ionomer, thermoplastic polyurethane, thermoplastic polyolefin, polymethyl methacrylate, polyvinyl butyral, polydimethyl silicon, ethylene-methyl methacrylate, and ethylene vinyl acetate.

11. The composition of any one of Claims 1 to 10, wherein the first optically transparent crosslinkable polymer is a host polymer

12. The composition of any one of Claims 1 to 11, wherein the first optically transparent crosslinkable polymer is a co-polymer.

13. The composition of any one of Claims 1 to 12, wherein the composition comprises multiple polymers.

14. The composition of any one of Claims 1 to 13, wherein the refractive index of the first optically transparent crosslinkable polymer is in the range of about 1.4 to about 1.7.

15. The composition of any one of Claims 1 to 14, wherein the composition further comprises a first crosslinking compound.

16. The composition of Claim 15, wherein the first crosslinking compound is selected from the group consisting of trifunctional acrylate, trifunctional methacrylate, zinc diacrylate, zinc dimethacrylate, and N-N'm-phenylene dimaleimide.

17. The composition of Claim 15, wherein the first crosslinking compound is a methacrylate.

18. The composition of Claim 15, wherein the first crosslinking compound is selected from the group consisting of ethylene glycol dimethacrylate, trimethyl propane trimethacrylate, Zinc diacrylate, Zinc dimethacrylate, triallyl cyanurate , triallyl isocyanurate, and high vinyl poly(butadiene).

19. The composition of Claim 15, wherein the first crosslinking compound is a hybrid crosslinker comprising polybutadiene diacrylate.

20. The composition of any one of Claims 15 to 19, wherein the first crosslinking compound is present in an amount in the range of about 0.01% to about 10.0% by weight of the composition.

21. The composition of any one of Claims 15 to 20, wherein the composition comprises a second crosslinking compound.

22. The composition of Claim 21, wherein the second crosslinking compound is selected from the group consisting of ethylene glycol dimethacrylate, trimethyl propane trimethacrylate, Zinc diacrylate, Zinc dimethacrylate, triallyl cyanurate , triallyl isocyanurate, and high vinyl poly(butadiene).

23. The composition according to any one of Claims 1 to 22, wherein the first organic chromophore is present in an amount in the range of about 0.01 wt% to about 3.0 wt%.

24. The composition of any one of Claims 1 to 23, wherein the composition further comprises a second organic chromophore.

25. The composition of any one of Claims 1 to 24, wherein the first organic chromophore is selected from the group consisting of a perylene derivative dye, a benzotriazole derivative dye, and a benzothiadiazole derivative dye.

26. The composition of any one of Claims 1 to 25, wherein the first organic chromophore comprises a structure as given by the following general formula (I):

wherein Ri, R₂, and R₃ comprise and alkyl, a substituted alkyl, or an aryl.

27. The composition of any one of Claims 1 to 26, wherein the composition further comprises a first adhesion promoter.

28. The composition of Claim 27, wherein the first adhesion promoter comprises acrylic silane material, vinyl silane material, epoxy silane material, or amino silane material.

29. The composition of Claim 28, wherein the first adhesion promoter comprises a methacrylate silane material.

30. The composition of Claim 29, wherein the first adhesion promoter comprises 3-Methacryloxypropyltrimethoxysilane.

31. The composition of any one of Claims 27 to 30, wherein the first adhesion promoter is present in an amount in the range from about 0.001% to about 2.0% by weight of the composition.

32. The composition of any one of Claims 27 to 31, wherein the composition comprises a second adhesion promoter.

33. The composition of any one of Claims 1 to 32, wherein the composition further comprises a first stabilizer.

34. The composition of Claim 33, wherein the first stabilizer is a photostabilizer.

35. The composition of Claim 33 or 34, wherein the first stabilizer is a hindered amine.

36. The composition of Claim 33, wherein the first stabilizer is a chromophore.

37. The composition of Claim 33, wherein the first stabilizer is selected from the group consisting of Tinuvin 144, Tinuvin 292, Tinuvin 622, Chimassorb 1 19, Chimassorb 944, Tinuvin 770, Tinuvin 791 , Tinuvin 783, Tinuvin 111 , and Tinuvin NOR371.

38. The composition of any one of Claims 33 to 37, wherein the first stabilizer is present in an amount in the range of about 0.001% to about 2.0% by weight of the composition.

39. The composition of any one of Claims 33 to 38, wherein the composition further comprises a second stabilizer.

40. The composition of any one of Claims 1 to 39, further comprising a first antioxidant.

41. The composition of Claim 40, wherein the first antioxidant is selected from the group consisting of a phenolic antioxidant, a phosphite antioxidant, and a thioether antioxidant.

42. The composition of Claim 40, wherein the first antioxidant is selected from the group consisting of Irganox 1010, Irganox 1076, Irgfos 168, butylated hydroxytoluene, Irganox PS 800, and Irganox PS802.

43. The composition of any one of Claims 40 to 42, wherein the first antioxidant is present in an amount in the range of about 0.001% to about 0.5% by weight of the composition.

44. The composition of any one of Claims 40 to 43, wherein the composition comprises a second antioxidant.

45. The composition of Claim 41 , wherein the second antioxidant is selected from the group consisting of a phenolic antioxidant, a phosphite antioxidant, a theoether antioxidant, Irganox 1010, Irganox 1076, Irgfos 168, butylated hydroxytoluene, Irganox PS 800, and Irganox PS 802.

46. The composition of any of Claims 1 to 45, further comprising an IR reflective agent.

47. The composition of Claim 46, wherein the IR reflective agent is selected from the group consisting of metal oxide, mica powder, composite oxide, Talc, titania, ceria, zirconia, silica, magnesia, clay, Kaolin, alumina, infrared pigment, and combinations thereof.

48. The composition of Claim 47, wherein the IR reflective agent is present in an amount of in the range of about 0.01% to about 30% by weight of the composition.

49. The composition of any of Claims 1 to 48, further comprises one or more of an IR absorber, an anti-fog agent, an anti-mist agent, an anti-drop agent, anti-dust agent, a lubricant, a modifier, an inorganic filler, and an anti-static agent.

50. A wavelength conversion layer formed by curing composition of any one of Claims 1 to 49.

51. The wavelength conversion layer of Claim 50, wherein the composition is cured at a temperature of between about 130 to about 180 degrees Celsius.

52. The wavelength conversion layer of Claim 50 or 52, wherein the layer is cured for a time ranging from about 5 to about 100 minutes.

53. An encapsulation structure for a solar energy conversion device comprising: the wavelength conversion layer of any one of Claims 50 to 52; wherein the wavelength conversion layer is configured to encapsulate a solar energy conversion device and inhibit penetration of moisture and oxygen into the solar energy conversion device; and

wherein the wavelength conversion layer is configured to encapsulate the solar energy conversion device such that light must pass through the wavelength conversion layer prior to reaching the solar energy conversion device.

54. An encapsulation structure for a solar energy conversion device comprising: the wavelength conversion layer of any one of Claims 50 to 52; and an environmental protective cover configured to inhibit penetration of moisture and oxygen into the wavelength conversion layer and the solar energy conversion device; and

wherein the wavelength conversion layer and the environmental protective cover are configured to encapsulate the solar energy conversion device such that light must pass through the wavelength conversion layer and the environmental protective cover prior to reaching the solar energy conversion device.

55. The encapsulation structure of Claim 54, wherein the environmental protective cover comprises glass or polymer sheets.

56. The encapsulation structure of Claim 54 or 55, further comprising a sealing tape around the perimeter of the solar energy conversion device.

57. The encapsulation structure of any one of Claims 54 to 56, further comprising one or more of a glass sheet, a reflective backsheet, edge sealing tape, a framing material, a polymer encapsulation material, or an adhesive layer to adhere additional layers to the system.

58. The encapsulation structure of any one of Claims 54 to 57, wherein the structure further comprises an additional polymer layer containing a UV absorber, an antioxidant, or any combination thereof.

59. A method of improving the performance of a solar energy conversion device, comprising encapsulating the device with the encapsulation structure of any one of Claims 54 to 58.

60. The method according to Claim 59, wherein the solar energy conversion device contains at least one device selected from the group consisting of a III-V or II- VI PN junction device, a Copper-Indium-Gallium-Selenium (CIGS) thin film device, an organic sensitizer device, an organic thin film device, a Cadmium Sulfide/Cadmium Telluride (CdS/CdTe) thin film device, an amorphous Silicon solar cell, a microcrystalline Silicon solar cell, a polycrystalline Silicon solar cell, and a crystalline Silicon solar cell.

61. A composition for producing a photostable wavelength conversion material for a solar energy conversion device comprising:

a first chromophore, a first optically transparent crosslinkable polymer, and a first crosslinking reagent,

with the proviso that the chromophore is not within an oxide microparticle.

62. A wavelength conversion layer formed by curing composition of Claim 61.

63. A composition for producing a photostable wavelength conversion material for a solar energy conversion device comprising: a first chromophore, a first optically transparent crosslinkable polymer, and a first crosslinking reagent,

wherein the at least one chromophore is a UV absorber.

64. A wavelength conversion layer formed by curing composition of Claim 63.

65. A composition for forming a photostable wavelength conversion material for a solar energy conversion device comprising:

a first organic chromophore;

a first monomer, wherein upon polymerization the monomer yields an optically transparent crosslinkable polymer; and

a first crosslinking reagent.

66. A greenhouse panel comprising:

at least one wavelength conversion layer of any one of Claims 50-52, 62, or

64.

67. A greenhouse solar collection panel comprising:

at least one wavelength conversion layer of any one of Claims 50-52, 62, or 64; and at least one solar energy conversion device.

68. A method of making a wavelength conversion layer comprising:

curing a composition of any one of Claims 1 to 49.

69. The method of Claim 68, wherein the curing step is performed at a temperature of between about 130 to about 180 degrees Celsius.

70. The method of Claim 68 or 69, wherein the layer is cured for a time ranging from about 5 to about 100 minutes.