Layer containing effect pigments and scattering additives

Abstract

The present invention relates to a layer, sheet or film containing one or more flake-form effect pigments and one or more light scattering centers, its method of preparation, its use in any kind of solar cell energy collector, including but not limited to the coloring of solar cells or solar cell modules, and solar cell energy collectors, including but not limited to colored solar cells or colored solar cell modules, comprising such a layer, sheet or film, as well as methods of preparation thereof.

Description

[Technical field]

[0001] The present invention relates to a layer, sheet or film containing one or more flake-form effect pigments and one or more light scattering centers, to a method for making same, to its use in any kind of solar cell energy collector, including but not limited to the coloring of solar cells or solar cell modules, and to solar cell energy collectors, including but not limited to colored solar cells or colored solar cell modules, comprising such a layer, sheet or film, as well as to a method for making same. [Background technology]

[0002] Solar cells have enjoyed great success over the past few years, exceeding 600 GW of international grid-connected capacity in 2019, the majority of which is installed at utility scale. The basic function of all solar cells relies on a photoactive material absorbing light to generate excited electron-hole pairs. These electron-hole pairs are separated within the solar cell by a region with different mobilities of electrons and holes, the so-called pn junction. As different types of light absorbing materials can be used, different solar cell technologies are known in the photovoltaic industry: 1) Crystalline silicon solar cells (single crystal c-Si and polycrystalline mc-Si) 2) Cadmium telluride solar cells (CdTe) 3) Copper-indium-gallium-diselenide (CIGS / CIS) 4) Amorphous silicon solar cells (a-Si) 5) III / V solar cells, such as gallium arsenide (GaAs) solar cells, or multijunction solar cells consisting of a stack of elements of groups III and V, such as germanium / indium-(aluminum)-gallium-arsenide or phosphide (In(Al)GaAs / P) 6) Dye-sensitized solar cell (DSSC) 7)Organic solar cells (OSC) 8) Perovskite solar cells (PSC) 9) Quantum dot solar cells (QSC) 10) Other II / VI solar cells made of elements of groups II and VI, such as zinc selenide (ZnSe) or iron sulfide (FeS) 11) Tandem solar cell However, the use of more surfaces, such as the surfaces of buildings and surfaces on other objects (e.g., cars), increases the total surface area that can be used for solar energy production. To this end, new techniques and approaches to create solar cells with attractive colors and hues, and to increase efficiency at various angles of incidence, are of great interest in the solar energy business. WO 2019 / 122079 A1 discloses a method for coloring state-of-the-art single solar cells, or solar cell modules made of multiple electrically interconnected solar cells, by incorporating effect pigments into an application medium, such as a glass colorant, or a transparent lamination or encapsulant, and then applying them to the front side of the solar cell. The effect pigments are semi-transparent and control the color of the light entrance surface without imparting solar cell efficiency. However, it has been observed that due to the semi-transparent coloring provided by the pigment-containing layer at the light incidence side, the solar cell structure and / or its conductive parts are still at least partially visible through the protective glass and the sealing film. The occurrence of such undesirable patterns is a drawback that may limit the use of colored solar cells, especially in areas such as building facades or other photovoltaic-integrated buildings. Furthermore, it has also been observed that the color intensity depends on the viewing angle, which may reduce the appeal of the color effect in certain applications. WO 2019 / 122079 A1 proposes using a homogenous dark colored background to enhance the uniformity of appearance and / or blackening the conductive parts of the solar module to reduce the occurrence of undesirable patterns, however this requires additional processing steps or components, increasing the time and cost of the solar module manufacturing process. US Patent No. 5,807,440 describes a colored photovoltaic device with a colored layer containing a colorant, pigment, or dye on the light-incident side, and further with a diffuser layer providing haze characteristics of 15-90%. The diffuser layer may contain white or nearly colorless pigment, porous resin dispersed in a translucent resin, or an incompatible resin. However, the examples in the document report that photovoltaic devices with a colored layer with an absorbing dye and an additional diffuser layer show a short-circuit current attenuation of 32-36% compared to a reference device without a diffuser layer. Furthermore, the use of a separate diffuser layer in addition to the colored layer complicates the solar cell module manufacturing process, increasing the time and cost of the process. Summary of the Invention

[0003] It is therefore an object of the present invention to provide improved color layers for solar cells and solar modules that are free of the drawbacks observed in prior art films, exhibit good color reflection intensity over a wide range of viewing angles, while avoiding undesirable visible patterns (e.g., of strings / busbars).It is another object of the present invention to provide improved color solar cells and color solar modules comprising such color layers, and a more time- and cost-effective method for producing the same.

[0004] Surprisingly, it has been found that one or more of the above objects can be achieved by providing a layer, sheet or film as disclosed and claimed below, which comprises one or more effect pigments and further comprises one or more light scattering centers, e.g. scattering particles, so that it does not appear transparent but shows a certain haze and still provides the desired color effect against a dark background. It has been found that by adding such a layer to the front side of a solar cell module, it is possible to reduce the occurrence of undesirable dark patterns of cells and strings / busbars in colored solar cells or solar cell modules and to reduce the viewing angle dependence of the color intensity, while still maintaining the high transmittance of the pigmented layer, thereby contributing to a high solar cell efficiency. Surprisingly, it has also been found that the light-scattering centers make the colored layer more opaque, masking uneven color and imparting a more uniform color throughout the solar panel, and at the same time, the efficiency of the solar cell is not significantly reduced by the light-scattering centers and may even be increased, as shown in the examples below. [Brief description of the drawings]

[0005] [Figure 1] FIG. 1 illustrates a solar cell module according to a preferred embodiment of the present invention. [Diagram 2] The corresponding transmittance values ​​(e.g. graph Ta) and the corresponding haze values ​​(e.g. graph Ha) are shown for the inventive films a) to e) with scattering particles of different sizes and types (Ta to e, Ha to e) and for reference films without added scattering particles (Tref, Href). [Diagram 3] The corresponding transmittance values ​​(graph Td, etc.) and the corresponding haze values ​​(graph Hd, etc.) are shown for the inventive films d), f) and g) with different concentrations of scattering particles E+520 (Td, Tf, Tg, Hd, Hf, Hg) and for a reference film without added scattering particles (Tref, Href). [Figure 4] Optical images of films obtained without scattering particles (A) and with 1% (B) or 2% (C) of scattering particles BMH-40 are shown against the background of a stacked solar cell with a front glass. [Diagram 5] The corresponding transmittance and haze (T1-2, H1-2) of a glass plate having layers 1 and 2 according to the invention and of a glass plate having a reference layer Ref1 (Tref1, Href1) are shown. [Figure 6] The transmittance values ​​of the coated samples are shown. [Figure 7] The light loss factor of the coated sample is shown, obtained by integrating the transmittance curves in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] The present application thus relates to a layer, sheet or film comprising one or more effect pigments consisting of a transparent or translucent flake-like substrate coated with one or more layers of transparent or translucent material and, optionally, a post-coating, and further comprising one or more light-scattering centers. The present application further relates to methods of making the above and below described layers, sheets or films. The present application further relates to the use of the above-mentioned and below-mentioned layers, sheets or films as coloured layers in solar cell modules, in particular as coloured sealing layers or glass colourants. The present application further relates to a coloured solar cell or a coloured solar cell module comprising the above and below mentioned layers, sheets or films. The present application further comprises the following components: - a transparent front cover layer (hereinafter also referred to as "front sheet" for short), - optionally a further transparent layer on the front side of the solar cell, - one or more solar cells or an array of solar cells electrically interconnected by conductive parts, preferably by busbars; -rear seat, wherein a transparent front cover layer, or a further transparent layer in front of the solar cell, comprises one or more effect pigments consisting of transparent or translucent flake-shaped substrates coated with one or more layers of transparent or translucent material and optionally a post-coating, and further comprises one or more light-scattering centers. The present application further relates to a method for producing the above and below described colored solar cells or colored solar cell modules.

[0007] Above and below, the term "light scattering centers" is understood to include various types of scattering centers, including but not limited to scattering particles or other additives, bubbles, droplets, density fluctuations in fluids, crystallites in polycrystalline solids, defects in monocrystalline solids, surface roughness, etc. The scattering effect caused by the scattering centers according to the invention can also be understood as diffuse reflection, in contrast to specular reflection, and means, unless otherwise specified, the scattering of light in the visible, UV and IR range, preferably in the range from 200 to 1200 nm, more preferably in the range from 300 to 1000 nm. In the above and below, the term "front side" of a solar cell or solar module means the side that receives light or faces the incident light, and the term "rear side" or "back side" of a solar cell or solar module means the side that faces opposite the side that receives radiation or faces opposite the incident light. The terms "front glass / sheet" or "front sealing film" mean glass, sheet or sealing film provided on the front side of a solar cell or solar module, and the terms "rear glass / sheet" and "rear sealing film" mean glass, sheet or sealing film provided on the rear side of a solar cell or solar module. Above and below, unless otherwise specified, the term "solar cell" is understood to encompass both single solar cells and solar cell modules, as well as arrays, strings or patterns of the foregoing. Similarly, the term "solar cell module" is understood to encompass single solar cells, unless otherwise specified. Above and below, unless stated otherwise, the weight percentages of light-scattering particles and effect pigments are based on the total weight of the layer, sheet or film. Above and below, the term "medium particle size D50" means the particle size in microns that divides the particle size distribution such that 50% of the particles have a size smaller than this value and 50% of the particles have a size larger than this value (also known as the median diameter). Unless otherwise stated, the medium particle size D50 is obtained with a Malvern MS2000 instrument. In the following, a layer, sheet or film according to the invention will also be called "layer" for short, which is understood to encompass a layer, sheet or film according to the invention described above or below.

[0008] The present invention provides a highly efficient method for coloring state-of-the-art solar cells and solar modules made of multiple electrically interconnected solar cells with great flexibility to achieve a wide range of different colors with low or negligible loss of solar cell efficiency and a high level of long-term stability. Furthermore, the present invention provides a solution for achieving high color uniformity and good color intensity at all viewing angles, while at the same time low or negligible loss of solar cell efficiency is achieved, while low visibility of the busbars and the individual single solar cells is achieved. It has thus surprisingly been found that by adding a light-scattering additive to the effect pigment-containing layer on the front side of the solar cell module, the occurrence of undesirable dark patterns of cells and strings / busbars in coloured solar cells or solar cell modules can be reduced or even avoided, reducing the viewing angle dependence of the colour intensity, while still maintaining a high transmittance of the pigment-containing layer, thereby ensuring high solar cell efficiency. In particular, it is surprising that when light-scattering additives are used in the pigment-containing layer, the light-scattering additives are preferably selected from transparent particles with diameters in the low micrometer range and act as scattering centers, increasing the haze of the pigmented layer and thereby increasing its hiding power, while at the same time having no or only a slight effect on its transparency and which may have a positive effect on the solar cell efficiency.

[0009] Furthermore, it has surprisingly been found that, in particular when used on the front side of a cover glass, the concentration of effect pigments in the layer can also be reduced when used in combination with light-scattering additives selected from optically transparent particles, so that the impact that the effect pigments may have on solar cell efficiency can be further reduced. In typical applications, the effect pigment concentration is ≥ 1 g / m 2It is desirable to have a high hiding power, otherwise the solar cell structure may still be visible, although the color impression is already strong. In addition to the high hiding power, the angle dependence of the color of the solar cell module is reduced. This, together with the increased efficiency due to the scattering particles themselves, opens up new possibilities for designing colored solar cell modules while making the power losses due to partial reflection of light by the effect pigment less noticeable. The layer containing the effect pigment and light scattering additive according to the invention was found to be ideal for providing sufficient color without significantly reducing the overall solar cell efficiency. Long-term tests showed a high level of stability. Since the direct contact between the effect pigment-containing film and the solar cell is the most demanding location in the construction of a solar cell module, it can be safely assumed that the effect pigment-containing film can be used at any other position in the solar cell module stack without any adverse effects. Effect pigments reflect a portion of the incident visible light, but allow the light needed to generate energy via the photovoltaic process to pass through. Effect pigments can be oriented so that the angle of maximum efficiency can be changed, thereby manipulating color and efficiency. The layer with effect pigments and light scattering additives can be easily applied to state-of-the-art solar cells, further improving the efficiency of their use. The processing step of applying the layer containing effect pigments and light scattering additives to the solar cell module can be easily integrated into existing state-of-the-art methods for producing encapsulated solar cell modules.

[0010] By using the present invention, the visual appearance of the solar cell can be adapted to specific needs. The visual appearance of the exterior of the object containing the solar cell, such as a building, device, or automobile vehicle, can be improved, and the transparency and reflectivity of the solar cell can be controlled. Furthermore, if a dark colored backsheet is used and the busbars and connection points are darkened, the visibility of the cell and the light colored busbars can be reduced or even avoided. The present invention can also be used to provide solar cells with special colors to achieve special effects and designs, and depending on the effect pigments used, textures can also be added, such as a glitter effect on the panel, imitation of a brick wall, or the color tones of different surfaces of materials used in house construction. Another advantage of the present invention is that, where the typical technical appearance of a solar cell changes the neutral design that people are familiar with, and where long-term stability is essential, by changing the appearance to the neutral design that people are more familiar with, the solar cell may be seamlessly integrated into any surface, such as the surfaces of buildings (facades and roofs), handheld, portable and stationary devices, automotive vehicles or other transport objects (cars, trucks, motorcycles, scooters, trains, ships, trailers, etc.), price tags, plastics, wearable items, and consumer electronics, or any other highly visible surface that requires seamless integration of the solar cell without changing the optical appearance, or other types of solar cell installations. The coloring of the solar cells is possible across a range of colors and is not limited to rigid substrates such as glass or single solar cell technology. Furthermore, complex solutions such as additional layers in the lamination stack are not necessary. The effect pigment-containing layers give the solar cell front surface appearance of different colors, such as red, purple, green, etc., and mixtures thereof. The thickness of the layers, the materials used in the layers, and the concentration of the effect pigments or combinations thereof may be varied to achieve a desired color effect. In particular, a wide color space / gamut can be achieved using combinations / mixtures of red, green, and blue effect pigments at different concentrations. Advantageously, the light scattering centers can be incorporated into the same layer as the effect pigments that provide the coloration of the solar cell module, reducing the number of separate layers and improving the time and cost efficiency of the module manufacturing process. Furthermore, in contrast to currently available technologies, which have a significant drawback in terms of their impact on solar cell performance, where solar cell efficiency can drop from an initial performance of over 15% to less than 10% in real life conditions, the efficiency of colored solar cells is not significantly affected, and therefore the cost of solar power will not increase significantly.

[0011] Surprisingly, effect pigments show the possibility of uniformly coloring solar cells with little effect on the cell efficiency, if the concentration of the effect pigments is appropriately selected. Surprisingly, it has also been found that conventional effect pigments, such as in particular pearlescent pigments, interference pigments and / or multilayer pigments, show the desired effect. The action principle of these effect pigments is based on the selective reflection of certain wavelength ranges, so that the color effect can be selectively adjusted and the resulting efficiency can be directly correlated to the transmitted portion of light. In general, the desired color effect can already be obtained with low reflection of certain wavelengths. The performance and efficiency of solar cells can be increased by appropriate selection of pigments and scattering additives, as shown in the following examples. Furthermore, it has surprisingly been found that the incorporation of light-scattering centers, on the one hand, leads to a haze in the pigment-containing layer according to the invention, which advantageously reduces the occurrence of dark patterns in solar cell array structures or in features such as electrically interconnecting bus bars, and on the other hand, does not significantly reduce the transmittance of the pigment-containing layer and, as a result, does not adversely affect the power conversion efficiency of the solar cell.

[0012] The light-scattering centers in the layer according to the invention are preferably selected from particles, bubbles, e.g. glass bubbles, droplets, and density variations in the pigment layer, all of which are capable of scattering light and are more preferably selected from particles which are optically transparent or translucent and may be organic or inorganic, hereinafter also referred to as "(light)-scattering particles". Very preferably, the light scattering particles in the layer according to the invention are SiO2, preferably silica spheres or silica powder, spherical silicone resin powder, and also BaSO4, Al2O3, BaMgAlO x or Eu-doped BaMgAlO x particles, or glass bubbles. Barium sulfate particles are commercially available in various sizes, such as the BMH series or B series, e.g., BMH40 or B-1, from, for example, Sakai Chemical Industry Co., Ltd. Spherical silicone resin powders are commercially available from, for example, ABC NanoTech Co. Ltd. in various sizes, such as E+508, E+520, E+540, etc. Glass Bubbles are available in a variety of sizes, such as S60, from, for example, 3M. Silica powder is available, for example, from Sibelco, in a variety of sizes, such as M500 and M800. The light scattering particles, such as spherical silicone resin powder, are preferably round in shape, such as spheres or granules, i.e. not platelet-shaped. The light scattering particles preferably have an average particle size, preferably a median particle size D50, of 0.1-10 μm, more preferably 0.2-8 μm, very preferably 0.5-6 μm, most preferably 1-4 μm. In another preferred embodiment, the particles have an average particle size, preferably a median particle size D50 of 2-10 μm, very preferably 3-6 μm. In the case of glass bubbles, the median particle size D50 is preferably in the range of 10 to 50 μm, more preferably in the range of 20 to 50 μm. Preferably, the concentration of light scattering particles in the layer according to the invention is in the range of 0.01 to 10%, more preferably 0.05 to 10%, even more preferably 0.05 to 5%, very preferably 0.05 to 3%, most preferably 0.1 to 1.5% by weight, preferably 0.1 to 10 g / m 2 It is.

[0013] The effect pigments in the layer according to the invention are preferably selected from pearlescent pigments, interference pigments and multi-layer pigments. The effect pigments are preferably based on synthetic or natural mica, flaky glass substrates, flaky SiO2 substrates or flaky Al2O3 substrates. The flaky substrates are preferably coated with one or more layers of metal oxides and / or metal oxide hydrates of Ti, Sn, Si, Al, Zr, Fe, Cr and Zn. The effect pigments used in the layers according to the invention are preferably transparent or at least translucent. The effect pigments useful in the invention preferably exhibit red, blue or green colors. However, other colors such as gray, white, purple, red or orange are also suitable. Other colors or mixtures thereof can be used to produce specific colors and shades. The effect pigments can also produce metallic effects, including but not limited to silver, platinum, gold, copper, and various other metals. It is also possible to use mixtures of different colors and variations in layer thickness to produce printed images / photos / hues.

[0014] The effect pigments preferably comprise, and very preferably consist of, a transparent or translucent flake-shaped substrate coated with one or more layers of transparent or translucent material and, optionally, a post-coating. Preferably, the effect pigments contain a flake-shaped substrate comprising at least one coating comprising a metal oxide, a metal oxide hydrate, or a mixture thereof. Preferably, the effect pigments consist of a transparent or translucent, colorless flake-shaped substrate, which is coated with one or more layers of a transparent or translucent, colorless material. The use of pearlescent pigments, interference pigments, and / or multi-layer pigments is preferred. As described, for example, in WO 2011 / 095326 A1 and below, the long-term stability of the effect pigments can be improved by using a post-coating of an organic and / or inorganic coating, preferably as the last layer of the effect pigment.

[0015] Suitable substrates for effect pigments are, for example, all known coated or uncoated flake-like substrates, preferably transparent or translucent, preferably colorless flakes.Suitable are, for example, phyllosilicates, in particular synthetic or natural mica, glass flakes, SiO2 flakes, Al2O3 flakes, TiO2 flakes, liquid crystal polymers (LCPs), holographic pigments, BiOCl flakes, or mixtures of the above flakes.In order to obtain a very high hiding power of the active photovoltaic layer, aluminum flakes with a dielectric coating can also be used in low concentrations according to the present invention. The glass flakes may consist of all glass types known to the person skilled in the art, such as A-glass, E-glass, C-glass, ECR-glass, recycled glass, window glass, borosilicate glass, Duran® glass, laboratory glass or optical glass. The refractive index of the glass flakes is preferably 1.45 to 1.80, in particular 1.50 to 1.70. Particularly preferred glass flakes consist of A-glass, C-glass, E-glass, ECR-glass, quartz glass and borosilicate glass. Preference is given to coated or uncoated flakes of synthetic or natural mica, SiO2 flakes, Al2O3 flakes, and glass flakes, in particular C-glass, ECR-glass or calcium aluminum borosilicate glass flakes. In particular, effect pigments based on calcium aluminum borosilicate glass are preferably used. In a variant of the invention, preference is given to Al2O3 flakes. The substrate generally has a thickness of 0.01 to 5 μm, in particular 0.05 to 4.5 μm, particularly preferably 0.1 to 1 μm. The length or width dimension is usually 1 to 500 μm, preferably 1 to 200 μm, in particular 5 to 125 μm. The substrate generally has an aspect ratio (ratio of average diameter to average particle thickness) of 2:1 to 25,000:1, preferably 3:1 to 1000:1, in particular 6:1 to 250:1. The above dimensions of the flake-shaped substrate also apply in principle to the coated effect pigments used according to the invention, since the additional coating is generally in the range of only a few hundred nanometers and therefore does not significantly affect the thickness or length or width (particle size) of the effect pigment.

[0016] The particle size and particle size distribution of the effect pigments and their substrates can be measured by various methods that are conventional in the art. However, preferably, laser diffraction methods are used with standard procedures using a Malvern Mastersizer 2000, Beckman Coulter, Microtrac, etc. Additionally, other techniques such as SEM (scanning electron microscope) images may be used. In a preferred embodiment, the substrate is coated with one or more transparent or semi-transparent layers comprising a metal oxide, metal oxide hydrate, metal hydroxide, metal suboxide, metal fluoride, metal nitride, metal oxynitride, or mixtures of these materials. Preferably, the substrate is partially or completely encapsulated in these layers.

[0017] Furthermore, there may also be a multilayer structure with high and low refractive index layers, which preferably alternate with each other. A layer package with high and low refractive index layers (refractive index ≧2.0) and low refractive index layers (refractive index <1.8) is particularly preferred, and one or more of these layer packages may be applied to the substrate. Here, the order of the high and low refractive index layers may be adapted to the substrate in order to include the substrate in the multilayer structure. Metal oxides, metal oxide hydrates or mixtures thereof, preferably of Ti, Sn, Si, Al, Zr, Fe, Cr and Zn, in particular Ti, Sn and Si, are particularly preferred. The oxides and / or oxide hydrates may be present in a single layer or in separate layers. In particular, titanium dioxide in the rutile or anatase modification, preferably in the rutile modification, is used. For conversion of titanium dioxide to the rutile modification, a tin dioxide layer is preferably applied under the titanium dioxide layer. A preferred multilayer coating comprises alternating high and low refractive index layers, preferably TiO2-SiO2-TiO2, etc. The metal oxide, hydroxide and / or oxide hydrate layers are preferably applied by known wet-chemical methods; wet-chemical coating methods developed for the preparation of effect pigments can be used, which result in the coating of the substrate. After application by wet-chemical methods, the coated product is subsequently separated, washed, dried and preferably calcined. The thickness of the individual layers is usually from 10 to 1000 nm, preferably from 15 to 800 nm, in particular from 20 to 600 nm, especially from 20 to 200 nm.

[0018] To increase the stability against light, temperature, water and weather, the effect pigments may be subjected to a post-coating or post-treatment. The post-coating may be an organic and / or inorganic coating as a final layer. The post-coating preferably comprises one or more metal oxide layers of the elements Al, Si, Zr, Ce; Fe, Cr or mixtures or mixed phases thereof. Furthermore, organic or organic / inorganic combination post-coatings are possible. Silanes and / or organofunctional silanes may also be used alone or in combination with metal oxides. Suitable post-coating or after-treatment methods are, for example, the methods described in DE 2 215 191 A, DE 3 151 354 A, DE 3 235 017 A or DE 3 334 598 A, EP 0 090 259 A, EP 0 634 459 A, WO 99 / 57204 A, WO 96 / 32446 A, WO 99 / 57204 A, U.S. Pat. No. 5,759,255 B1, U.S. Pat. No. 5,571,851 B1, WO 01 / 92425 A, WO 2011 / 095326 B1 or other methods known to a person skilled in the art.

[0019] Effect pigments that can be used in the present invention are, for example, commercially available interference pigments or pearlescent pigments offered under the trade names Iriodin®, Pyrisma®, Xirallic®, Miraval®, Colorstream®, Spectraval®, RonaStar®, Biflair® and Lumina Royal®. Other commercially available effect pigments may also be used. In particular, Colorstream®, Xirallic®, Miraval® and Ronastar®, Pyrisma® pigments may be used.

[0020] In a preferred embodiment, the layer according to the invention comprises a mixture of different effect pigments, more preferably two or more, very preferably three or more different effect pigments. This makes it possible to obtain special effects. In a preferred embodiment, the effect pigments can be mixed in any proportion, but preferably the total content of all effect pigments in the layer should not exceed 60% by weight. In a highly preferred embodiment, the layer according to the invention comprises a mixture of red, green and blue effect pigments. Depending on the concentrations, a larger color space / gamut can thereby be achieved. The concentration of the effect pigments in the layer according to the invention is preferably in the range from 0.01 to 40% by weight, preferably from 0.01 to 20% by weight, more preferably in the range from 0.01 to 15% by weight, in particular in the range from 0.1 to 10% by weight, most preferably in the range from 0.1 to 8% by weight. In another preferred embodiment, the m 2 The amount of effect pigment per unit is 0.1 g / m 2 ~75g / m 2 More preferably, it is in the range of 0.2 to 30 g / m 2 in the range of 0.5 to 15 g / m 2 , and most preferably 0.5 to 6 g / m 2 It is.

[0021] The layer according to the present invention containing the effect pigments and the light-scattering centers can in principle be selected from any suitable transparent material, including, but not limited to, polymer-, sol-gel-, polysilazane-, glass- or ceramic-based layers. In a preferred embodiment of the invention, the layer containing the effect pigments and the light-scattering centers is a polymer film. Preferred polymer films are polyolefin polymers or copolymers, especially polyethylene polymers or copolymers, including but not limited to polyethylene, EVA (ethylene vinyl acetate), EBA (ethylene butyl acrylate), EMA (ethylene methyl acrylate), EEA (ethylene ethyl acrylate), POE (polyolefin elastomer), BPO (polyolefin copolymer), as well as PVB or TPU (thermoplastic polyurethane), preferably EVA or polyethylene copolymers. In another preferred embodiment of the invention, the layer containing effect pigments and light-scattering centers is a glass, ceramic or enamel layer. In this application, the layer is preferably provided on a glass sheet or glass article. The thickness of the layer containing the effect pigments and the light-scattering centers is preferably in the range from 5 μm to 1000 μm, more preferably from 20 μm to 800 μm, even more preferably from 200 μm to 600 μm for polymer films, preferably in the range from 10 μm to 300 μm for ceramic layers, more preferably from 20 μm to 200 μm and most preferably from 30 μm to 100 μm for glass, ceramic or enamel layers. Effect pigments and light scattering particles can be incorporated into the layers of the invention by methods known to those skilled in the art and described in the literature. If the layer according to the invention is a glass, ceramic or enamel layer, the layer can be produced, for example, by mixing the effect pigments and light-scattering particles with a glass frit or flux, ceramic or enamel precursor, placing the mixture on a substrate and baking or firing the mixture at a temperature above the glass temperature of the glass frit, flux, ceramic or enamel, respectively.

[0022] Typical methods of applying the precursor composition to a substrate include roller coating, screen printing, or spraying a mixture of the flux, enamel or ceramic precursor, scattering agent, and pigment in a solvent (e.g., water or glycol ether). In particular, in the decoration of glass articles, especially glass plates, a precursor composition containing one or more pigments, one or more light scattering additives and one or more glass frits or fluxes is preferably used. The precursor composition is baked after coating on a substrate, thereby forming a glass-enamel containing pigments and light scattering additives. In the application of the precursor composition to a glass plate, it is desirable to adjust the melting behavior of the precursor composition according to the typical conditions of a tempering process. Typical baking conditions are a glass temperature of about 580°C to 650°C and a baking time of several minutes. To colorfully decorate glass plates in the glass area of ​​architecture and instruments, a good compatibility is required between the glass frits contained in the composition with inorganic pigments. The requirements of the baked composition, i.e. the requirements of the glass-enamel, include smooth running at as low a temperature as possible, short baking times, avoidance of cracks, good chemical resistance to acid and alkaline materials, and good weather resistance in many fields of use. Preferred fluxes are cadmium and lead free fluxes based on Si, Zn and B, such as those based on borosilicate glass.

[0023] When the layer according to the invention is a polymer film, it can be prepared by extrusion methods such as melt extrusion of a polymeric material, whereby the effect pigments and scattering particles are added to the polymer melt before extrusion. In extrusion, the thermoplastic is melted into a viscous mass in a screw and then pressed through a flat die to create a shape. The variety of possible shapes is enormous: films, foils and plates can be extruded through flat dies. Usually, masterbatches or compounds are used to color the molten mass with effect pigments and scattering particles. To obtain satisfactory results in plastic extrusion with effect pigments and additives, it is necessary to maintain a balanced ratio between mixing energy and pigments and / or particles that are as undamaged as possible. Excessive shear in the mixing section or inappropriate screws or filters will destroy the effect pigments and dramatically reduce the pearlescent effect. Pigment orientation is crucial for a uniform effect. This needs to be ensured through corresponding engineering and machine design in the process.

[0024] In a preferred embodiment of the present invention, a masterbatch containing the desired amount of effect pigments and scattering particles, e.g. 5-30% by weight, in a polymeric material is added during the extrusion process of the polymeric film, which can be done for example by making a premix of the pigmented masterbatch pellets with EVA pellets or by any other known method. The shear forces acting on the effect pigments during the melt extrusion process cause the effect pigments to orient substantially parallel to the surface of the seal film. In another preferred embodiment, the layer containing effect pigments and scattering particles is a coextruded film of two or more layers of the same or different polymeric materials, one of which, preferably the layer facing the front sheet, contains one or more effect pigments. EVA is a thermosetting polymer that is used as an encapsulant for lamination of PV modules and whose formulation is especially adapted for use in solar applications. EVA provides high electrical insulation, transparency, flexibility and pliability. In crosslinked formulations (such as for encapsulants), EVA also exhibits high dimensional stability, fast cure and easy lamination. A typical EVA formulation typically includes crosslinkers, adhesion promoters, UV absorbers, UV stabilizers and antioxidants in addition to the polymer resin. The crosslinkers are radical initiators (usually peroxides) that decompose with heat during lamination to form free radicals in the polymer backbone that initiate radicals. The formed radicals then result in the formation of covalent bonds between the polymer chains. The layer according to the invention can also provide a color tone or color pattern, for example imitation of a brick wall can be achieved by screen printing two different colors in a desired pattern, and the color tone of different surfaces of materials used in house construction can be achieved, for example, by spraying two different colors from each other.

[0025] The effect of pigments and layers on c-Si solar cells is evaluated by reflectance data, which is used to estimate the maximum power absorption / maximum photocurrent generation of the processed cells. Reflectance and transmittance measurements and calculations are performed by common methods known to those skilled in the art, as further described in the experimental section. The haze of the layer containing the effect pigments and the light scattering centers can be determined from the transmittance as described in Example 1. The transmittance of the layer comprising effect pigments and scattering additives is preferably ≧60%, more preferably ≧70%, very preferably ≧75%, most preferably ≧80% for light in the range from 500 to 800 nm, more preferably in the range from 450 to 900 nm, very preferably in the range from 400 to 1000 nm and most preferably in the range from 350 to 1150 nm. The reflectance of the layer comprising effect pigments and scattering additives is preferably <40%, more preferably <30%, very preferably <25%, most preferably <20% for light in the range 450-800 nm, more preferably in the range 400-1000 nm, most preferably in the range 300-1150 nm. The haze of the layer comprising effect pigments and scattering additives is preferably ≧50%, more preferably ≧60%, very preferably ≧70%, most preferably ≧80% for light in the range from 500 to 800 nm, more preferably in the range from 450 to 900 nm and most preferably in the range from 350 to 1150 nm.

[0026] The present application also relates to the use of the above and below layers as coloured layers, in particular as coloured sealing layers, in any type of device for collecting and converting solar energy, such as solar thermal or photovoltaic devices, including but not limited to organic photodiodes, solar cells or solar cell modules (which may be organic, inorganic or hybrid). The present application further relates to a device for collecting and converting solar energy, such as a solar thermal or photovoltaic device, including but not limited to an organic photodiode, a solar cell or a solar cell module (which may be organic, inorganic or hybrid), comprising a layer according to the invention as described above and below.

[0027] A preferred solar cell or solar cell module according to the invention comprises the following components: 1) a transparent front sheet, preferably glass or a plastic film such as polycarbonate, Plexiglas, TPT (Tedlar®-polyester-Tedlar®, where Tedlar® is a PVF (polyvinyl fluoride) film available from DuPont); 2) optionally one or more further transparent layers on the front side of the solar cell, preferably selected from polymer films or ceramic layers provided on a front glass sheet, which also function as an encapsulation film or front sheet; 3) a solar cell or a string or array of electrically interconnected solar cells; 4) optionally one or more further layers on the rear side of the solar cell, preferably selected from polymer films; 5) A transparent rear sheet, preferably glass or a plastic film, such as polycarbonate, Plexiglas, TPT (Tedlar® - polyester - Tedlar®, Tedlar® is a PVF (polyvinyl fluoride) film available from DuPont), etc. The front sheet, component 1), comprises one or more effect pigments as described above and below and one or more light-scattering centers, or the solar cell or solar cell module comprises a further front transparent layer as component 2), which comprises one or more effect pigments as described above and below and one or more light-scattering centers.

[0028] The components are stacked in the following order: 1) front sheet, 2) optional additional transparent layer on the front side, 3) solar cells, 4) optional additional layer on the rear side, 5) rear sheet. A solar cell module according to a preferred embodiment of the invention is exemplarily and diagrammatically shown in Figure 1 and comprises a transparent front sheet (11), preferably a glass sheet, a transparent layer according to the invention containing effect pigments and light scattering centers (12), an array of solar cells with busbars (13), and a rear sheet (14), which is preferably black or dark in colour. The arrows indicate the direction of incident light. In a preferred embodiment, one or more further sealing films (not shown in Figure 1) are provided between the pigment-containing layer (12) and the solar cell (13) and / or between the solar cell (13) and the rear sheet (14). The further sealing films do not contain effect pigments or light-scattering centers. In another preferred embodiment (not shown in FIG. 1), the solar cell module does not contain a front sheet (11), and the transparent layer containing the effect pigments and light-scattering centers (12) serves as the front sheet. In another preferred embodiment (not shown in FIG. 1), the layer containing the effect pigments and light scattering centers (12) functions as a seal film. In another preferred embodiment (not shown in FIG. 1), a protective or outer foil is applied over the finished solar cell or solar module.

[0029] The components located on the front side of the solar cell module, such as the front sheet (11), the layer film (12), and the optional further front encapsulation film, are substantially transparent to the incident light passing through the solar cells or solar cell array (13). The front sheet (11) and the rear sheet (14) are preferably selected from glass sheets. In another preferred embodiment, the front sheet (11) and / or the rear sheet (14), more preferably the rear sheet (14), are polymer sheets, preferably TPT or polycarbonate sheets. The front and rear polymer films are preferably selected from organic polymers, including but not limited to, for example, polyolefins such as polyethylene, EVA (ethylene vinyl acetate), EBA (ethylene butyl acrylate), EMA (ethylene methyl acrylate), EEA (ethylene ethyl acrylate), POE (polyolefin elastomer), polyethylene polymers or copolymers such as BPO, as well as polyesters, polyamides, polyurethanes, polyvinyl butyral PVB, polycarbonates, polyvinyl chloride, polyvinyl acetate, polyacrylates, polyols, polyisocyanates or polyamines, as well as copolymers, resins, blends or multilayers of the above, such as polycarbonate-containing urethane resins, vinyl chloride-vinyl acetate-containing urethane resins, acrylic resins, polyurethane acrylate resins, polyester resins, or TPUs (thermoplastic polyurethanes). If the front transparent layer is a polymer film, it is preferably selected from polyolefin polymer or copolymer films, very preferably from polyethylene polymer or copolymer films, in particular from EVA, EBA, EMA, EEA, POE, BPO, PVB or TPU films, most preferably from polyethylene copolymer or EVA films.

[0030] Further preferred polymers for use as or in rear sheets can be classified as double fluoropolymers, single fluoropolymers, and non-fluoropolymers, as well as various structures within each category. Double fluoropolymer rear sheets typically consist of an outer layer of Tedlar® polyvinyl fluoride (PVF) film or Kynar® polyvinylidene fluoride (PVDF) film, with a core layer of polyethylene terephthalate (PET). Single fluoropolymer rear sheets typically consist of Tedlar or Kynar® on the air side, with PET and a primer or EVA layer on the inside. Non-fluoropolymer rear sheets typically consist of two PET layers and one primer or EVA layer.

[0031] The solar cell array (13) as exemplarily shown in FIG. 1 may be replaced by a single solar cell. The solar cells (13) can be selected from any type of solar cell technology including amorphous, monocrystalline and polycrystalline silicon solar cells, CIGS, CdTe, III / V solar cells, II / VI solar cells, perovskite solar cells, organic solar cells, quantum dot solar cells, and dye-sensitized solar cells, as well as solar cell modules made of single cells. Crystalline solar cells include cell structures such as Al-BSF, PERC, PERL, PERT, HIT, IBC, bifacial, or any other cell type based on a crystalline silicon substrate. The rear sheet (14) is preferably black or dark in colour and / or a black or dark sheet, e.g. a rear sealing film or an additional sealing film, is provided on the rear side of the solar cell or solar module, i.e. between the solar cell (13) and the rear sheet (14), the dark colour being preferably dark blue equal to the colour of the solar cell.

[0032] In the solar cell (13), the conductive parts preferably include metal-based conductive parts, including but not limited to the following parts: i) H-grids consisting of main vertical connectors, also known as busbars; ii) Horizontal current collectors - the so-called fingers, iii) Connectors and solder between the solar cells. In a preferred embodiment of the present invention, in order to achieve a completely uniform appearance of the solar cell (13), the metal-based conductive parts, including but not limited to the above parts i) to iii), are preferably pigmented in a dark colour, such as black or dark solar blue, before application to the layer (12) with the effect pigments and light-scattering centres. In another preferred embodiment of the present invention, a dark, preferably black or dark blue, grid is incorporated into at least one or more layers of the solar cell, said grid covering light areas such as the spaces between the single solar cells and the conductive parts including bus bars, conductive tracks and solder joints. In another preferred embodiment, a black or dark blue backing layer is applied behind the solar cells to hide the spaces between the single solar cells. The black or dark blue backing layer can be printed or applied as a foil. A suitable and preferred approach to darken the otherwise white-looking metal parts of the solar cells (13) with an H-grid front pattern is to cover the metal stripes with a black polymer foil or to brush the metal parts with black paint. In the case of a printed silver H-grid, the silver can be directly blackened by forming a thin layer of silver sulfide (e.g. by treatment with H2S) or by plating and oxidizing copper. In the case of plated metal grids, the top layer of the metal stack can be directly plated with highly absorbing metal oxides or sulfides such as CuO or Ag2S, or similar darkly colored metal oxides, etc. When using novel metallization schemes (such as smart wire technology), blackened wires or wires with microstructures that reduce reflectivity and thus create a dark appearance of the metal grid can also be used according to the invention. When a black or dark blue rear sheet of the solar cell is used as the background of the module, a very uniform overall module appearance can be achieved even from a close distance. The front, rear and further sealing films preferably comprise, very preferably consist of, TPU or a polyolefin, including but not limited to EVA, EBA, EMA, EEA, POE or BPO, most preferably EVA.

[0033] The layer (12) containing effect pigments and light-scattering centers is arranged on the radiation-receiving side, i.e. in the visible part of the solar cell or solar cell module according to the invention. The layer may be arranged on the inside of the front sheet (11) in the solar cell module, i.e. on the side facing the solar cell or array of solar cells, as shown in Figure 1, or it may be arranged on the outside of the front sheet (11), i.e. on the side facing the incident light. The coloured ceramic layer according to the invention is used on the outer (weather-exposed) surface of the cover glass, to which a preferably transparent protective layer is added, which can be based, for example, on a CVD layer of an oxide or on a wet-coated film, for example a film of a polysilazane. The layer (12) with effect pigments and light-scattering centers can be applied topically and flexibly to any surface, thus it can be applied either to the outside of a finished solar cell or solar cell module, onto a protective substrate (glass or plastic) covering the solar cell or solar cell module, or directly onto the photoactive material / solar cell. Advantageously, the layer (12) comprising effect pigments and light-scattering centers can also be used as an anti-reflection film.

[0034] A solar cell module or a plurality of solar cell modules according to the present invention can be fabricated by processes known to those skilled in the art and described in the literature. If the layer with effect pigments and light-scattering centers is a glass, ceramic or enamel layer, the layer is preferably produced on a glass substrate as described above, and the glass substrate covered by the layer with effect pigments and light-scattering centers is provided on top of other individual components or layers of the above- or below-described solar cell module stacked in the desired order. The ceramic or enamel layer with effect pigments and light-scattering centers on the glass substrate can be incorporated into the solar cell or can form an outer layer. If said layer forms an outer layer, it is preferably protected by a protective layer. The protective layer can be applied on top of the colored enamel or ceramic layer. If the layer comprising the effect pigments and the light-scattering centers is a polymer film, preferably said polymer film and other individual components or layers of the solar cell module described above or below are stacked in the desired order and then laminated together, for example by applying heat and / or pressure or by using an adhesive or bonding agent. Alternatively, the lamination process for producing the solar cell module or a plurality of solar cell modules can also be carried out in two steps, in which in a first lamination (or pre-lamination) step, a layer containing effect pigments and light-scattering centers is laminated to a front sheet, and then in a second lamination step, said front sheet plus the laminated layer containing effect pigments and light-scattering centers is laminated to the remaining stack of components.

[0035] Thus, a preferred method for producing a colored solar cell or a colored solar cell module according to the invention comprises the following steps: a) laminating a layer, preferably a polymeric film, containing one or more effect pigments and one or more light scattering centers to the front sheet, preferably by applying heat and / or pressure or by using an adhesive or bonding agent or bonding layer, preferably in a vacuum press, b) optionally cooling the front sheet with the laminated layer containing the effect pigments and the light-scattering centers, preferably to room temperature; c) A stack containing the following layers: C1) optionally, one or more front sealing films; C2) one or more solar cells or an array of solar cells electrically interconnected by conductive components, preferably by bus bars; C3) optionally, one or more rear sealing films; C4) Rear seat, on a front sheet having a laminated layer containing effect pigments and light-scattering centers, or on a stack of layers C1 to C4, d) Laminating the stack of layers C1-C4, preferably by application of heat and / or pressure or by using an adhesive or bonding agent, preferably in a vacuum press, to a front sheet having a laminated layer containing effect pigments and light-scattering centers. The lamination step, like steps a) and d) above, can be carried out by standard methods, e.g. by applying heat and pressure to the two layers, e.g. by applying vacuum and / or any other form of physical pressure, for a specific time interval, e.g. in a laminator. Alternatively and / or additionally, lamination can be achieved or assisted by the use of one or more adhesives and / or bonding agents or layers. The adhesives / bonding agents may be reactive or non-reactive and may include or consist of natural or synthetic materials. Suitable and preferred examples include, but are not limited to, polyurethane (PUR), thermoplastic polyurethane (TPU), rubber, acrylic and silicone adhesives, depending on the desired application. After the first step or pre-lamination step a), if heat was applied for the lamination, the front sheet laminated with the layer containing effect pigments and light-scattering centers is preferably cooled in step b), very preferably to room temperature. The layer containing effect pigments and light-scattering centers is then permanently fixed to the glass and cannot be peeled off by hand. The pigments are distributed evenly on the surface. In the next step c), the remaining stack of optional front encapsulant, solar cell, optional rear encapsulant and rear sheet is placed on top of the pre-laminated bilayer of the front glass and the layer with effect pigments and light-scattering centers, or the pre-laminated bilayer is placed on top of the remaining stack, preferably with the pre-laminated bilayer facing the solar cell, with the layer with effect pigments and light-scattering centers facing the solar cell. The final lamination of the stack is then carried out in step d), preferably under conditions similar to those of the pre-lamination.

[0036] In the lamination step, as in steps a) and d) above, suitable applied heat and pressure and time intervals depend on the type of sheets and films used and can be easily selected by a person skilled in the art. When a windshield sheet and a polymer film of EVA are used, preferably the heating temperature is in the range of 130°C to 160°C, very preferably about 135°C, and the time interval is preferably 20 to 30 minutes. Preferably, a vacuum press is used. Preferably, a pressure of 400 to 900 mbar is applied. After the last lamination step d), the laminate stack is cooled again, preferably to room temperature. Excess material of the sealing film and the rear sheet (if a plastic rear sheet is used) can be cut off and a junction box can be attached for the electrical connection of the solar module. Finally, the laminate can be assembled. The thickness of the film after the lamination step is usually reduced depending on the lamination conditions. Preferably, the resulting laminate is completely hermetic and, in the ideal case, can protect the solar cells for at least 25 years.

[0037] Preferably, the solar cells and solar modules according to the invention exhibit a power variation ΔP of >−5%, more preferably >−2%, very preferably >0.1%,

number

[0038] The following examples are intended to illustrate the invention without limiting it. Example 1 - Polymer Film with Effect Pigments and Scattering Particles Film preparation Various polyethylene films according to the invention were coated with 0.15% of the effect pigment Iriodin® 7235 Ultra Rutile Green Pearl at a concentration of 1 g / m 2 The effect pigments were obtained in a concentration of 0.1 to 1.0% by weight and further made to contain in each case one of the light-scattering particles listed below. a) 1% barium sulfate BMH-40 particles (mean particle size D50 is 5 μm) b) 1% barium sulfate B-1 particles (mean particle size D50 is 0.5 μm) c) 1% spherical silicone resin powder E+508 (medium particle size D50 is 0.8 μm) d) 1% spherical silicone resin powder E+520 (medium particle size D50 is 2 μm) e) 1% spherical silicone resin powder E+540 (medium particle size D50 is 4 μm) f) 0.5% spherical silicone resin powder E+520 (medium particle size D50 is 2 μm) g) 2% spherical silicone resin powder E+520 (medium particle size D50 is 2 μm) h) 0.5% spherical silicone resin powder E+540 (medium particle size D50 is 4 μm) i) 2% spherical silicone resin powder E+540 (medium particle size D50 is 2 μm) j) 1% glass bubbles S60 (mean diameter D50 is 30 μm) All of the added particles are light scattering and optically transparent themselves.

[0039] For comparison purposes, a reference film containing 0.15% of the effect pigment Iriodin® 7235 Ultra Rutile Green Pearl but with no added scattering particles was prepared as above. Sealing films are usually produced by extrusion of cast films, but for practical reasons, in this example, film samples 10 x 15 cm in size and 700 mm thick were produced by injection molding of polyethylene resin containing pigments and particles as follows. A Kraus-Maffei CX-130-380 type injection molding machine was used. After the mold was closed, a transparent plastic melt (Evatane® 28-25PV, product of Arkema) was injected into the injection mold. The injection operation was carried out at temperatures ranging from 180 to 200°C and pressures of 450 to 900 bar (4.5×10 7 N / m 2 ~9×10 7 N / m 2 ) pressure range. For coloring the plastic melt or adding scattering particles, masterbatches were used depending on the required concentration. If necessary, the polymer film was embossed in a post-process. Embossing the structure usually aids in the removal of air during the lamination step of the solar module.

[0040] Transmittance and haze measurements The transmittance of the films according to the invention and the reference film was measured with a Cary UV / Vis spectrometer equipped with an integrating sphere (following ASTM D1003). The haze of the films according to the invention and the reference film was calculated from the transmittance measurements according to the following formula: Haze(%)=((T4 / T2)-(T3 / T1))·100 where T1 denotes the reference value of the incident light when there is no sample in the sample holder and the reflectance standard is in the measurement position, T2 is the transmitted light of the test sample when there is a sample in the sample holder and the reflectance standard is in the measurement position (only the light directly transmitted through the sample is measured), T3 is the reference scattered light measurement from the spectrometer itself when there is no sample in the holder and the reflectance standard is not at the measurement point, and T4 is the scattered light measurement from the spectrometer when there is a sample in the sample holder and the reflectance standard is not in the measurement position (all the light transmitted through the sample is measured). FIG. 2 shows the corresponding transmittance values ​​(graph Ta, etc.) and the corresponding haze values ​​(graph Ha, etc.) for the inventive films a) to e) having scattering particles of different sizes and types as described above (Ta to e, Ha to e) and for reference films without added scattering particles (Tref, Href). From Figure 2, it can be seen that the film with scattering particles exhibits better haze compared to the reference film, especially in the visible region. It can also be seen that the haze increases with increasing scattering particle size, but the scattering particles have only a small effect on the transmittance of the film. FIG. 3 shows the corresponding transmittance values ​​(graph Td, etc.) and the corresponding haze values ​​(graph Hd, etc.) for inventive films d), f) and g) having different concentrations of scattering particles E+520 as described above (Td, Tf, Tg, Hd, Hf, Hg) and for a reference film without added scattering particles (Tref, Href). From Figure 3, it can be seen that the film with scattering particles exhibits better haze, especially in the visible region, compared to the reference film. It can also be seen that the haze increases with increasing scattering particle concentration, but the scattering particles have only a small effect on the transmittance of the film.

[0041] Use of polymer films as solar cell encapsulants The films c), d) and e) according to the present invention, each containing 1% of spherical silicone resin powder E+508, E-520 and E-540 of different sizes, and the reference film were respectively used as encapsulants to cover the solar cells of a solar flasher, and the effect on the solar cell efficiency was measured using a Wavelab Sinus7 solar simulator. A flash tester (solar flasher or solar simulator) is used to measure the output performance consistency of solar PV modules. During a flash test, the PV module is exposed to a short (1ms-30ms), bright (100mW per square cm) flash of light from a xenon arc lamp. The output spectrum of this lamp is chosen to be as close as possible to the spectrum of the sun. The output is collected by computer and voltameter. The data can be compared to a reference solar module. The results are shown in Table 1. [Table 1]

[0042] From Table 2, it can be seen that small particles of 0.8 μm have little effect on solar cell efficiency, while larger particles d) and e) of 2 or 4 μm have very little effect. At the same time, Figure 2 shows that these particles produce films with increased haze and only a small decrease in transmittance. To investigate the effect of scattering particle concentration, the films d) to i) according to the present invention and the reference film were respectively used as encapsulants covering the solar cells of a solar flasher, and the effect on the solar cell efficiency was measured using a Wavelab Sinus7 solar simulator as described above. The results are shown in Table 2. [Table 2]

[0043] From Table 2, it can be seen that in all cases the particles have little effect on the solar cell efficiency, and the effect becomes more pronounced with increasing particle concentration. Surprisingly, even at small particle concentrations the solar cell efficiency is also increased compared to the reference. This can be attributed to improved absorption of scattered photons by the solar cell, as evidenced by an increased photocurrent. Overall, the above results on the transmittance and haze values ​​of the films on the one hand, and the efficiency data of solar cells containing the films as encapsulant on the other hand, demonstrate that the addition of scattering particles to the pigment-containing film leads to the desired haze with only a slight decrease in transmittance, while the solar cell efficiency is not significantly affected or even slightly improved.

[0044] Example 2 - Polymer Film with Effect Pigments and Scattering Particles Film preparation To investigate the effect of scattering additives on the optical appearance and efficiency of solar cell structures, a 0.15% (or 1 g / m 2 Glass samples were prepared consisting of two glass panels 3 mm thick laminated with a 700 μm thick extruded EVA film containing the effect pigment Iriodin® 7235 Ultra Rutile Green Pearl (D50 5 μm) and a scattering additive selected from barium sulfate particles BMH-40 (D50 5 μm) or barium sulfate particles B-1 (D50 0.55 μm) or Glass Bubbles S60 (D50 30 μm) at a concentration of 1% or 2%. For comparison purposes, a reference film was prepared as above with 0.15% of the pigment Iriodin® 7235 Ultra Rutile Green Pearl but no scattering particles added.

[0045] Transmittance and Haze Figure 4 shows optical images of films obtained without scattering particles (A) and with 1% (B) or 2% (C) of scattering particles BMH-40 against a background of a stacked solar cell with a windshield. It can be seen that the films with scattering particles exhibit a haze that reduces (B) or makes the background virtually invisible (C). Use of polymer films as solar cell encapsulants To investigate the effect on efficiency, the films were tested using a flash tester mounted on a commercial perovskite single solar cell. A controlled set of LEDs providing a spectral range from 350 nm to 1100 nm was used as the light source, and the power output was measured using a Wavelab Sinus7 solar simulator and a voltameter. The results are shown in Table 3. [Table 3]

[0046] From Table 3 it can be seen that the addition of particles has only a small detrimental effect on the cell efficiency. Overall, the results demonstrate that the addition of scattering particles to pigmented films results in the desired haze, while the solar cell efficiency is not significantly affected or even slightly improved.

[0047] Example 3 - Enamel layer with effect pigments and scattering particles Preparation of layers The enamel layer was printed on a glass plate using a manual screen printer with a 48 mesh screen, resulting in a film thickness of 36 μm. The enamels used were standard enamels obtained from the ceramic industry and contained 2% Iriodin® 7235 Ultra Rutile Green Pearl or Iriodin® 7225 Ultra Rutile Blue Pearl as color pigments, resulting in a pigment concentration in the dry film of about 1.4 g / m 2In addition to adding silica powder of different particle sizes, haze and transmittance were measured. The particles used were quartz powder with a mean diameter D50 of 4 μm (M500) at a concentration of 0.5% in the paste or 0.4 g / m2 in the dry film, or quartz powder with a mean diameter D50 of 1.8 μm (M800) at a concentration of 0.5% in the paste or 0.4 g / m2 in the dry film. The films were then fired in a fast firing furnace to a glass temperature of 620°C to fuse the enamel and leave a clear glass layer containing the pigment and silica powder. For comparison purposes, a reference enamel layer was prepared as above with the same pigment concentration but without the addition of scattering particles. The pigment and particle concentrations of the individual layers are listed in Table 4 below. [Table 4]

[0048] Transmittance and haze measurements The transmittance and haze of the glass plates having enamel layers 1 to 4 containing the effect pigment according to the invention and silica powder, and of the glass plates having reference enamel layers Ref1 and Ref2 containing only the effect pigment, were measured and calculated as described in Example 1. FIG. 5 shows the corresponding transmittance and haze of a glass plate having layers 1 and 2 according to the invention (T1-2, H1-2) and of a glass plate having a reference layer Ref1 (Tref1, Href1). From FIG. 5 it can be seen that compared to the reference layer, the scattering particles do not change the transmittance of the enamel layer but increase the haze.

[0049] Use of enamel layers as solar cell encapsulants The glass plates with the enamel layers 1 to 4 according to the invention and the reference layers 1 and 2 were placed over the solar cells on a solar flasher and the effect of the enamel layers on the solar cell efficiency was measured as described in Example 1. The results are shown in Table 5. [Table 5] From Table 5, we can see that in all cases, the power output is enhanced rather than adversely affected by the addition of scattering particles, which can be attributed to the fact that light scattering by the particles results in improved absorption of photons by the solar cell, since the light after scattering does not hit the solar cell at a steep angle. Overall, the results demonstrate that the addition of scattering particles to a pigmented enamel layer results in the desired haze, while on the other hand the solar cell efficiency is not significantly affected or is even improved.

[0050] Example 4 - Coating with effect pigments and scattering particles Preparation of coatings The spray coating formulations were applied to the cover glass of a solar module. The formulation consisted of a 20% solution of polysilazane as binder in butyl acetate as solvent, in which the effect pigment Xirallic® T-60-23 was present at a concentration of 6%. The scattering particles used were barium sulfate particles BMH-40 with an average particle diameter D50 of 5 μm. Different formulations were prepared with particle concentrations varying from 0 to 3%. Each formulation was applied manually with a standard spray coating device and, after application, dried at 200 °C for 2 hours. The thickness of the coated film is 2 g / m for all selected cases. 2 This gave a pigment concentration of For comparison purposes, a reference coating was prepared as above with the same pigment concentration but without the addition of scattering particles. The pigment and particle concentrations of the individual films are listed in Table 6 below. [Table 6]

[0051] Transmittance and haze measurements After a drying step, the transmittance of the coated samples was measured with a Cary Photo spectrometer and integrating sphere as described in Example 1. FIG. 6 shows the transmittance values ​​of the coated samples. From FIG. 6 it can be seen that scattering particle concentrations up to 3% show an increase in the hiding power of any structure behind the glass, but the total transmittance does not decrease. FIG. 7 shows the optical loss factor of the coated samples, obtained by integrating the transmittance curves in FIG. From FIG. 7 it can be seen that the light loss rate shows a decrease with scattering particle concentration up to 3%. The results demonstrate that the layer according to the invention has additional haze that prevents the generation of undesirable shadows or patterns due to the colored layer, and allows efficient coloring of solar cell modules without significant negative or even positive impact on solar cell efficiency.

Claims

1. A layer, sheet, or film comprising one or more effect pigments consisting of a transparent or translucent flake-like substrate coated with one or more layers of transparent or translucent material, which may be coated with a post-coating, and further comprising one or more light-scattering centers.

2. The layer, sheet, or film of claim 1 , wherein the light scattering centers are selected from particles, bubbles, droplets, and density variations.

3. 10. The layer, sheet, or film of claim 1, wherein the light scattering centers are selected from transparent or translucent organic or inorganic particles.

4. The light scattering center is SiO 2 , preferably silica spheres or silica powder, spherical silicone resin powder, BaSO 4 , Al 2 O 3 , BaMgAlO x or Eu-doped BaMgAlO x 10. The layer, sheet, or film of claim 1, wherein the particles are selected from the group consisting of particles and glass bubbles.

5. 2. The layer, sheet or film according to claim 1, wherein the concentration of the light scattering centers in the layer is in the range of 0.01 to 5% by weight.

6. 2. The layer, sheet, or film according to claim 1, having a transmittance of 70% or more for light in the range of 400 to 1000 nm.

7. 2. The layer, sheet, or film of claim 1, having a haze of 50% or greater for light in the range of 400 to 1000 nm.

8. 2. A layer, sheet or film according to claim 1, characterized in that the effect pigments are selected from pearlescent pigments, interference pigments and multilayer pigments.

9. The effect pigments are made of synthetic or natural mica, glass flake substrates, SiO flakes, 2 Substrate or flake Al 2 O 3 2. A layer, sheet or film according to claim 1, characterized in that it is based on a substrate.

10. 10. The layer, sheet, or film of claim 9, wherein the flaky substrate is coated with one or more layers of metal oxides and / or metal oxide hydrates of Ti, Sn, Si, Al, Zr, Fe, Cr, and Zn.

11. 10. A layer, sheet, or film according to claim 1, characterized in that it comprises two or more different effect pigments.

12. 2. The layer, sheet or film according to claim 1, wherein the amount of effect pigment in the layer is in the range of 0.01 to 15% by weight.

13. 2. A layer, sheet or film according to claim 1, characterized in that the thickness of the layer containing the effect pigment and the light-scattering additive is in the range of 5 to 1000 μm.

14. 10. The layer, sheet, or film of claim 1, which is a polymer-based, sol-gel-based, polysilazane-based, glass-based, or ceramic-based layer.

15. 10. The layer, sheet, or film of claim 1 which is a polymeric film.

16. 10. The layer, sheet or film of claim 1, which is a polymer sheet / film selected from polyolefins, very preferably polyethylene, or copolymers thereof.

17. 10. The layer, sheet, or film of claim 1 which is a polymer sheet / film selected from EVA, EBA, EMA, EEA, POE, PC, and BPO films, or PVB or TPU sheets / films.

18. 10. The layer, sheet, or film of claim 1 which is a glass, ceramic, or enamel layer.

19. 19. A method for making a layer, sheet or film according to any one of claims 1 to 18 by melt extrusion of a polymeric material, wherein the one or more effect pigments and one or more scattering additives are added to the polymer melt before extrusion.

20. 20. A method of making a layer, sheet, or film according to claim 19 by mixing the one or more effect pigments and one or more scattering additives with a glass frit or a ceramic or enamel precursor, coating, printing, or spraying the mixture onto a substrate, and firing the mixture at a temperature above the glass temperature of the glass frit, ceramic, or enamel, respectively.

21. 10. The layer, sheet, or film of claim 1 which is an encapsulation film or sheet for a solar cell module.

22. A colored solar cell or colored solar cell module comprising a layer, sheet or film according to any one of claims 1 to 18 and 21.

23. The following components - a transparent front cover layer, - optionally, a further transparent layer on the front side of the solar cell; one or more solar cells or an array of solar cells electrically interconnected by conductive parts, preferably by busbars; -rear seat, 10. A colored solar cell or a colored solar cell module comprising: a transparent front cover layer or a further transparent layer in front of the solar cell, the transparent front cover layer being the layer, sheet, or film according to claim 1.

24. 24. The colored solar cell or colored solar cell module of claim 23, wherein the rear sheet is black or dark in color, and / or the colored solar cell or colored solar cell module includes an additional sheet or sealing film provided between the solar cell or solar cell array and the rear sheet, the additional sheet or sealing film being black or dark in color.

25. 24. The colored solar cell or solar cell module according to claim 23, characterized in that the electrically conductive parts interconnecting the solar cells are colored black or dark before application of the layer comprising the effect pigment and the light-scattering additive.

26. 24. The colored solar cell or solar cell module of claim 23, wherein a dark grid is incorporated into the solar cell or solar cell array, the grid covering light areas including, but not limited to, the space between the solar cell and the conductive component.

27. A colored solar cell or colored solar cell module as described in claim 23, characterized in that the transparent front cover layer and / or rear sheet is a glass sheet.

28. A colored solar cell or colored solar cell module as described in claim 23, characterized in that the transparent front cover layer and / or rear sheet is a polymer sheet.

29. 24. The colored solar cell or colored solar cell module according to claim 23, characterized in that it is selected from amorphous, monocrystalline and polycrystalline silicon solar cells, CIGS, CdTe, III / V or II / VI solar cells, perovskite solar cells, quantum dot solar cells, organic solar cells, and dye-sensitized solar cells.

30. 30. A method of making a colored solar cell or colored solar cell module according to any one of claims 23 to 29 by stacking components or layers as defined in any one of claims 1 to 17 and 23 to 29 in the desired order and then laminating said components or layers together by applying heat and / or pressure or by using an adhesive or bonding agent.

31. 31. The method of claim 30, wherein the layer, sheet, or film containing the effect pigment and the light-scattering additive is laminated to the transparent front cover layer in a first lamination step, and the transparent front cover layer with the laminated layer, sheet, or film containing the effect pigment and the light-scattering additive is laminated to the remaining stack of components in a second lamination step.

32. 31. A method according to claim 30, characterized in that the laminating step is carried out by applying heat and / or pressure or by using an adhesive or bonding agent or bonding layer, preferably in a vacuum press.

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