Patterned photovoltaic module

Abstract

The invention relates to an optoelectronic module comprising a cover plate having self-cleaning surface properties. By implementing specific surface structures (e.g., periodic dot patterns and quasi-periodic wave structures) with precise structural depth / height and pitch (non-patterned regions), the present invention achieves a substantial reduction in dust adhesion. The present invention also introduces a direct laser interference pattern manufacturing method which allows the manufacture of an optoelectronic module comprising a cover plate having self-cleaning surface characteristics, which can ensure a high dust removal rate, thereby maintaining the performance and efficiency of the module for a long period of time.

Description

Technical Field

[0001] The present invention relates to a photovoltaic module, including a cover sheet with self-cleaning surface properties. A photovoltaic module (e.g., as known from photovoltaic modules) includes at least one photovoltaic device. Photovoltaic devices (e.g., LEDs, photovoltaic cells (solar cells), and photodiodes) are semiconductor devices that operate according to the principle of the photoelectric effect, or photovoltaic effect, which occurs within the device's functional layers. In an LED, the injection of a forward voltage across a semiconductor junction (i.e., two regions of semiconductor material with different doping levels, typically forming a pn junction) causes electron-hole recombination, resulting in light emission (electroluminescence). Conversely, in a solar cell, incident photons generate electron-hole pairs, which, due to the built-in electric field, generate a voltage. Similar to solar cells, photodiodes react to light by generating electron-hole pairs, thereby generating a measurable current or voltage. Typically, photovoltaic devices (particularly photovoltaic cells) have a layered structure, i.e., composed of one or more layers (preferably at least two layers), including or constituting at least one functional layer. A photovoltaic module preferably comprises at least one photovoltaic device, which is combined with or electrically connected to another photovoltaic device so that the two devices function as a single unit.

[0002] In order to maintain the functionality of the photovoltaic module, the photovoltaic module also includes at least one cover plate to protect one or more underlying functional layers of the photovoltaic device contained therein from the influence of the surrounding environment of the photovoltaic module. This is particularly important for photovoltaic cells in solar panels, because solar panels are often located in exposed locations, such as rooftops, open spaces or desert areas.

[0003] However, the efficiency of photovoltaic modules (especially solar cells) depends on how well light can penetrate the cover to interact with the underlying functional layers. Surface contamination (especially the outer surface of the cover) with dirt or dust can lead to a sharp drop in energy output. Studies have shown that a dust layer as thin as 1 / 100 inch (about 0.25 mm) can reduce energy output efficiency by approximately 1% to 2%. Other publications have found that efficiency can be reduced by at least 3% to 4% due to cover contamination. Background Art

[0004] Photovoltaic modules, particularly solar panels, require a cover because they often operate in harsh environmental conditions, such as desert regions characterized by high dust and / or dryness. A dusty environment refers to an area with high levels of dust particles or particulate matter in the air. Similarly, in temperate climates, pollution and / or pollen and / or dirt carried by rain or animals can affect the transparency of the cover, leading to so-called fouling of the photovoltaic module. To address this issue, several approaches have been introduced in the prior art to provide photovoltaic modules with cover panels that are more resistant to fouling.

[0005] For example, CN 111293971 B introduces a wear-resistant, self-cleaning solar panel that includes an inverted microstructure filled with superhydrophobic nanomaterials. This technology proposes a solar panel that includes a transparent substrate and a microstructure filled with superhydrophobic nanomaterials to form a composite plane. The material properties are affected by the angle, side length and spacing of the microstructures. The nanomaterials are integrated together using advanced deposition methods (e.g., spin coating). However, the solar panel disclosed in the document also has inherent disadvantages. First, the preparation process requires at least two steps, which may increase the complexity and cost of manufacturing. In addition, the coating application is prone to poor adhesion to the substrate, posing challenges to long-term durability and performance. In addition, the coating may also have irregularities, which may affect the efficiency and reliability of the solar panel. Over time, the self-cleaning properties of the coating may degrade, requiring maintenance and potentially affecting the effectiveness of the solar panel.

[0006] However, coatings have also been optimized in many aspects. For example, Jaesung Son et al. ("A practical superhydrophilic self-cleaning and antireflective surface for outdoor photovoltaic applications," in Solar Energy Materials and Solar Cells, Vol. 98, March 2012, pp. 46-51) also describe a photolithography process that uses etching technology to create nanostructures by applying a coating and placing a mask on it. The resulting coating ensures that the surface has superhydrophilicity and self-cleaning properties as well as an antireflective effect. The disadvantage is that the production of such coatings is very complicated. In addition, the materials used for the coating and etching processes are not only expensive but also harmful to the environment.

[0007] A. Lasagni et al. (“High-speed surface functionalization rising direct laser interference patterning, toward 1 m² / min fabrication speed with sub-pm resolution,” Proc. of SPIE, Vol. 8968 8968012-1, 2014 SPIE) describe a DLIP process for patterning aluminum zinc oxide (AZO) layers. Laser interference patterning is performed using two sub-beams or via a diffraction beam splitter (DBS), generating multiple sub-beams. The resulting structures are either linear or hexagonal. To generate hexagonal structures, the line interference patterns are generated one by one with a 60° rotation angle. The disadvantage of this method is that multiple exposures are required. Therefore, it is complex and prone to errors. To set the interference period, the method described in this paper uses a suitable lens with the corresponding focal length. The disadvantage of this method is that the interference period can only be set for existing lenses, and once the interference period is adjusted, it must be readjusted. Furthermore, due to the type of pattern selected, the selected process is not suitable for producing structures with self-cleaning properties, as this would hinder the accumulation of dust. Summary of the Invention

[0008] Technical issues

[0009] A technical problem of the prior art is to provide a photovoltaic module that can maintain a high efficiency during operation even under harsh environmental conditions.

[0010] More specifically, the technical problem solved by the present invention is to ensure that photovoltaic modules (especially solar panels) continue to maintain a high level of sunshine by reducing the impact of particle accumulation on the surface of photovoltaic modules (especially solar panels).

[0011] Furthermore, the present invention, as disclosed herein, solves the technical problem of providing a durable cover plate for a photovoltaic module, which cover plate can reliably maintain its self-cleaning properties over a prolonged period of time.

[0012] Solution

[0013] The photovoltaic module according to claim 1 solves the above technical problem, and comprises:

[0014] - A cover plate (32), the cover plate having self-cleaning surface properties, the cover plate having an outer surface (42) and an inner surface (43), wherein the cover plate (32) is at least partially transparent, wherein the outer surface (42) and / or the inner surface (43) comprises a patterned area (28) and a non-patterned area (29), wherein the patterned area (28) is formed by a first periodic dot structure, the first periodic dot structure is formed by at least one first interference pixel (10) having a first interference period (p1), wherein the first interference pixel (10) comprises a periodic dot matrix consisting of at least three protrusions (46) or inverted protrusions (14), in particular protrusions or inverted protrusions.

[0015] In the present invention, a photovoltaic module includes at least one cover plate. The cover plate is preferably a durable, large-area substrate, in particular a transparent or partially transparent substrate. The cover plate preferably serves to seal the underlying layer or substrate from harmful environmental influences. In this context, the cover plate defines the photovoltaic module in at least one spatial direction; in other words, it represents the end of the photovoltaic module in this spatial direction. Depending on the intended use of the photovoltaic module, the cover plate is designed to allow light to enter the photovoltaic module and / or to allow light to escape from the photovoltaic module. For example, the cover plate in a solar panel separates the individual photovoltaic cells from the surrounding environment and is the first layer through which light entering the photovoltaic cell from the outside passes.

[0016] According to the present invention, the cover plate includes an outer surface that faces the environment surrounding the photovoltaic module. This outer surface forms part of the cover plate and is exposed to the harmful effects of contamination, particularly dirt, such as dirt caused by dust, dirt, precipitation, and / or pollution. Because the accumulation of pollutants or contaminant particles directly affects the efficiency of the photovoltaic module, it is crucial to prevent contaminant particles from adhering to the outer surface. Furthermore, according to the present invention, the photovoltaic module also includes an inner surface that faces the underlying substrate. The outer and inner surfaces each form an interface at which incident light is reflected, thereby increasing the efficiency and power output loss of the photovoltaic module. Therefore, to improve transparency, a high transmittance of incident light at this interface is desirable.

[0017] For purposes of this invention, transparent refers to a material or substance that allows light to pass through with minimal absorption or scattering. Specifically, transparent materials transmit light across the visible spectrum (electromagnetic radiation with wavelengths between approximately 380 nm and 700 nm) as well as certain portions of the infrared and ultraviolet spectra, with a transmittance of at least 50%, preferably at least 70%, more preferably at least 85%, and most preferably at least 95%. This allows light across a wide spectral range to be transmitted to the underlying functional layers.

[0018] According to the present invention, the patterned substrate or patterned cover includes a modified region, which includes a patterned region and a local non-patterned region. The modified region includes a first interference pixel, wherein the first interference pixel is formed by a first periodic pattern, and the first periodic pattern is composed of at least three surface irregularities (especially surface indentations), and the distance between these surface irregularities is an average structural period. These surface irregularities constitute the patterned region. The local non-patterned region refers to an area in the modified region that remains flat, that is, an area that does not display irregularities, separating the surface irregularities from each other.

[0019] According to the present invention, the periodic dot-like structure is formed by at least three surface irregularities, the distance between these surface irregularities being an average structural period. The surface irregularities preferably correspond to protrusions or inverted protrusions, in particular inverted protrusions, more preferably in the shape of an inverted cone. The distance from the saddle point of each protrusion to the saddle point of the next protrusion corresponds to the average structural period or interference period. The interference period is the distance in one direction between the center of one surface irregularity (preferably a surface indentation) and the center of an adjacent surface irregularity, wherein the distance is the same for the number of surface irregularities used.

[0020] The term “interference pixel” or “DLIP pixel” is well established in the literature on surface structuring by direct laser interference patterning (e.g., Alamri and Lasagni, “Development of a general model for direct laser interference patterning of polymers,” in Optics Express, Vol. 25, No. 9; 2017; Storm et al., “How to Tailor Structural Colors for Extended Visibility and White Light Generation Employing Direct Laser Interference Patterning,” in Macro-Molecular Chemistry and Physics, Vol. 220, No. 13, July 2019; Madelung et al., “Scanner-Based Direct Laser Interference Patterning on Stainless Steel,” in Advanced Engineering Materials, Vol. 23, No. 6, June 2021; Peter et al., “Direct laser interference patterning of stainless steel by ultrashort pulses for antibacterial surfaces,” in Optics and Laser Technology, No. 123, 2020, and refers to a spatial region, preferably on a substrate surface, where laser (sub-)beams directed toward the surface constructively and destructively interfere with each other, thereby forming a periodic pattern of intensity minima and intensity maxima. This region is preferably spatially confined so that the area it encompasses is significantly smaller than the substrate surface.

[0021] The present invention is characterized in that the interference period (p1) of the first periodic dot structure is in the range of 50 nm to 50 μm, preferably in the range of 500 nm to 30 μm, and more preferably in the range of 1 μm to 20 μm. Selecting an interference period within this range is advantageous because the resulting structural period has the same range as the interference period, which facilitates the generation of patterns that have been observed to reduce dust adhesion. The reduced adhesion of particles to the exterior and / or interior surfaces of the described photovoltaic modules is fundamentally related to the interaction between the surface pattern (e.g., periodic dots, line structures, or layered arrangements) and the particles themselves (as disclosed herein). Micro- or nano-scale surface topography engineering modifies the physical contact area between dust or dirt particles and the substrate. This modification is crucial for reducing effective adhesion forces, particularly controlling van der Waals forces, which are interactions at the micro or nano scale. Van der Waals forces are distance-dependent interactions between molecules or particles and surfaces. By introducing patterns of specific size and shape, the actual contact area between the particles and the substrate surface is significantly reduced. This reduction in contact area reduces van der Waals forces, which weaken at greater distances and when the interacting surfaces are not closely matched. As a result, particles, especially small ones, are less strongly attached to the substrate and are more easily dislodged by minimal forces (e.g., a gentle air flow). Additionally, structured surfaces can create air pockets or increase microscale roughness, further reducing the effective contact points between particles and the substrate. This effect not only reduces van der Waals adhesion, but also affects other adhesion mechanisms, such as capillary forces in the presence of moisture. By carefully designing the size and arrangement of the patterns, the surface properties of the cover sheet can be tuned to effectively minimize adhesion forces. This approach represents a strategic application of surface engineering to enhance the self-cleaning capabilities of photovoltaic modules, thereby ensuring higher operating efficiency, lower maintenance requirements, and longer device lifetimes.

[0022] Thus, the cover sheet, and in particular the surface (preferably the outer surface) of the cover sheet including the above-described pattern, can reduce dust adhesion by at least 40%, preferably at least 55%, more preferably at least 60%, and most preferably at least 63%, compared to a non-patterned cover sheet, and in particular compared to a non-patterned outer surface. Advantageously, this improves the efficiency of the photovoltaic module over time.

[0023] Furthermore, the invention disclosed herein is characterized in that the average particle size (more preferably, the average particle size distribution) of the contaminants on the cover plate (particularly on the surface of the cover plate, preferably the outer surface) is less than 50 μm, preferably less than 30 μm, more preferably less than 20 μm, most preferably less than 12 μm, and particularly preferably less than 6 μm. Thus, the average particle size of the contaminants on the cover plate is within the range of any two of the following endpoints: 50 nm, 48 nm, 46 nm, 44 nm, 42 nm, 40 nm, 38 nm, 36 nm, 34 nm, 32 nm, 30 nm, 28 nm, 26 nm, 24 nm, 22 nm, 20 nm, 18 nm, 16 nm, 14 nm, 12 nm, 10 nm, 8 nm, 6 nm, 4 nm, 2 nm. Advantageously, the reduction in particle size has a positive impact on the solar radiation received by the photovoltaic module, as it reduces the impact of the contaminants on the transparency of the cover plate.

[0024] Further advantageous embodiments can be found in the dependent claims and the description.

[0025] Advantages

[0026] Photovoltaic modules featuring nanostructured, self-cleaning surfaces offer numerous advantages, achieving revolutionary functionality and performance without the need for additional coatings. This innovative design not only eliminates the need for additional coatings, simplifying manufacturing processes and reducing costs, but also improves maintenance ease through its inherent self-cleaning properties. By effectively blocking dust and debris, active cleaning becomes less frequent and easier, optimizing operational efficiency and minimizing downtime.

[0027] Furthermore, the module's durability is significantly increased due to the nanostructure's robustness, which allows it to withstand environmental stress and mechanical wear. This durability ensures extended service life and maintained performance even under harsh operating conditions.

[0028] Furthermore, the incorporation of nanostructures helps to significantly reduce reflections, maximizing light absorption and energy conversion efficiency. This enhances the power output of photovoltaic modules and improves their overall performance, making them ideal for applications ranging from solar panels to optical devices.

[0029] The nanostructure's adaptability to environmental challenges further enhances the module's versatility, allowing it to be tailored to specific requirements and optimized for various applications. This adaptability ensures optimal functionality and efficiency under varying environmental conditions, making the module highly versatile and resilient.

[0030] Furthermore, due to the simplicity and efficiency of nanostructure fabrication techniques, the manufacturing process for photovoltaic modules has the advantages of fast processing speed and low cost. These technologies enable fast production cycles and simplified manufacturing processes, thus achieving cost-effective production and scalability for large-scale deployment.

[0031] Furthermore, the low process costs associated with nanostructure fabrication contribute to overall cost savings, making photovoltaic modules an economically viable solution for widespread application across various industries.

[0032] Photovoltaic modules

[0033] According to the present invention, a photovoltaic module is formed from at least one functional layer and at least one cover plate, as described herein, wherein the cover plate and the functional layer are arranged so as to form a unit comprising the photovoltaic module, preferably stacked on top of one another, wherein the cover plate delimits the photovoltaic module in one spatial direction, i.e., forms an interface between the photovoltaic module and the surrounding environment. Preferably, the cover plate delimits the photovoltaic module in the stacking direction (S), i.e., in the spatial direction in which the cover plate and the functional layer are connected to one another, which can also take into account the height of the photovoltaic module. Thus, the photovoltaic module is characterized by a stacked structure, which simplifies the manufacturing process and the handling and / or customization of specific components of the stack, such as by handling the cover plate separately before connecting it to the functional layer or by handling it as a unit.

[0034] In the context of the present invention, the cover plate itself consists of a substrate having a thickness significantly greater than the interference period of the interference pixels used. Preferably, the thickness of the substrate of the cover plate is at least 10 times, more preferably at least 100 times, most preferably at least 150 times, and in some cases preferably at least 200 times, greater than the depth of the inverted protrusions or the height of the protrusions located in the modified areas of the outer and / or inner surface of the cover plate. For example, the thickness of the substrate of the cover plate is in the range of 10 μm to 6,000 μm, more preferably in the range of 100 μm to 6,000 μm, and most preferably in the range of 200 μm to 6,000 μm. Preferably, the thickness is in the range obtained by combining any two of the following endpoint values: 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1,000 μm, 1,500 μm, 2,000 μm, 2,500 μm, 3,000 μm, 3,500 μm, 4,000 μm, 4,500 μm, 5,000 μm, 5,500 μm, 6,000 μm. Therefore, it can provide sufficient stability and durability for the photovoltaic module. Preferably, the cover plate is a bulk substrate composed of a single material or a single layer of a single material with encapsulated particles. Therefore, the cover plate is preferably characterized by its single layer or single-layer structure, i.e., it is made of a single layer without further coatings and is not made of a stack of several different layers composed of different materials. This makes material selection and manufacturing processes easier.

[0035] Therefore, the cover plate is preferably a block substrate defined therein, commensurate with the depth of the inverted protrusions or the height of the protrusions, the cover plate consisting of a single layer of a material having a thickness substantially greater than the depth of the inverted protrusions or the height of the protrusions located within the modified regions of the outer and / or inner surfaces of the cover plate as described above. Because this is the case, according to a preferred embodiment of the present invention, the cover plate can also be a coating made of a single layer, preferably consisting of a single material or a single material with encapsulated particles, wherein the coating is characterized by the thickness as defined above. This has the advantage that the coating can be applied to a transparent cover substrate, forming a direct seal to the interior of the photovoltaic module, and that the coating can impart other properties to the cover substrate, such as optical properties, for example, anti-reflective properties, hydrophobic or hydrophilic properties for increased self-cleaning capabilities, mechanical durability for increased resistance to scratches, abrasion, and wear, or the coating can be designed to adjust thermal conductivity for temperature regulation and alter electrical properties for electronic applications.

[0036] According to the present invention, the cover plate is made of a component that is not a functional layer or a part thereof. Preferably, the cover plate comprises or consists of a transparent material. Preferably, the material is selected from mineral glass, quartz glass, sapphire glass (Al2O3), aluminosilicate glass, zirconium oxide (ZrO2), glass-ceramic systems (composite materials made of glass and crystal), such as MAS systems (MgO×Al2O3×nSiO2 systems), ZAS systems (ZnO×Al2O3×nSiO2 systems), LAS systems (Li2O×Al2O3×nSiO2 systems), and mixtures thereof. Glass has high transparency and good durability, making it suitable for use in harsh climates and environmental conditions.

[0037] According to a preferred embodiment, the cover plate is configured such that it includes at least two largely flat surfaces, one of which is considered an outer surface and the other an inner surface. In the context of the present invention, the outer surface is the surface facing the surroundings of the photovoltaic module, while the inner surface is the surface facing or in contact with the functional layers of the photovoltaic module. In the context of the present invention, flat refers to a surface having a projected surface area (representing the total area of ​​the surface projected onto a flat plane) that exhibits only minor deviations from the actual surface area, preferably less than 5%, and more preferably less than 2%.

[0038] In the context of the present invention, a functional layer refers to an optoelectronically active layer that operates based on the conversion of photons into electrical energy (particularly electric potential), or vice versa. The functional layer comprises or consists of a material, preferably a semiconductor material, in which an electric current can be excited by incoming photons, causing electrons to reach a higher energy state. As a result, electrons are separated from the covalent bond system in which they are located, leaving behind a positive charge, also known as a hole, thereby forming an electrostatic potential, i.e., a voltage. The electrons and holes formed are all mobile within the material of the functional layer, although their direction of movement is limited by material properties such as the lattice structure and electrostatic potential, as well as any external potential that may be applied. Through the movement of electrons and holes, direct current (DC) can be collected.

[0039] For the purposes of the present invention, a photovoltaic active layer is a layer that can be designed as a layer stack and consists of a material or material combination that, due to its properties, allows electrical energy to be converted into electromagnetic waves or photons, and vice versa. A possible suitable base material is silicon or a material combination such as GaAs, InP, SiGe, ZnO or GaN as an inorganic semiconductor. Organic semiconductors and / or typical materials of thin-film solar cells (such as CdTe) are also possible. A variety of materials facilitates the production of photovoltaic modules suitable for different use cases, from industrial to residential sectors, including the transportation sector and possibly the aviation and space exploration sectors.

[0040] According to a preferred embodiment of the present invention, the photovoltaic module includes at least one additional stacking component configured to provide structural support and / or electrical insulation to the functional layer. Preferably, this at least one additional stacking component forms the bottom of the stack comprising the photovoltaic module, i.e., the side facing the functional layer that does not face the cover plate. Advantageously, this component seals the backside of the functional layer, thereby completing the protective housing that isolates it from the surrounding environment, thereby increasing the lifespan of the photovoltaic module.

[0041] According to a preferred embodiment, the at least one additional stack component serves as a connecting layer, comprising means for connecting the functional layers or parts of the functional layers in a manner that allows current flow for energy harvesting. Thus, the configuration of the photovoltaic module can be simplified.

[0042] patterned substrates

[0043] According to one embodiment of the present invention, a patterned cover sheet, in particular a surface of the cover sheet, comprises a completely non-patterned area characterized by a flat, i.e., regular, surface area that is undisturbed by surface irregularities that are arranged at a distance from one another equal to an average structural period. The completely non-patterned surface area is further characterized by a low surface roughness, where the surface roughness is quantified by its projected surface area, which represents the total surface area projected onto a flat plane. For the completely non-patterned area of ​​the surface, the deviation between the projected surface area and the actual surface area is low, preferably less than 10%, more preferably less than 5%, and most preferably less than 2%.

[0044] According to a preferred embodiment of the present invention, the cover sheet, in particular at least one surface of the cover sheet, preferably the outer surface of the cover sheet, comprises a non-patterned area comprising at least 20%, preferably at least 30%, more preferably at least 40%, and most preferably at least 50% of the total surface area. In this embodiment, the surface comprises a modified region or regions consisting of patterned and partially non-patterned regions, comprising surface irregularities spaced apart by an average structural period, wherein the modified region or regions comprise less than 80%, preferably less than 70%, more preferably less than 60%, and most preferably less than 50% of the total surface area. This advantageously reduces processing time, as only a portion or selected portion of the surface area needs to be processed, thereby increasing manufacturing yield and saving costs, while still maintaining self-cleaning surface properties.

[0045] According to a preferred embodiment of the present invention, the cover plate, in particular at least one surface of the cover plate, preferably the outer surface of the cover plate, includes a local non-patterned area arranged within the modified area (also called interference pixel) and accounting for at least 20%, preferably at least 30%, more preferably at least 40%, and most preferably at least 50% of the total surface area of ​​the modified area or interference pixel. Thus, this ratio of the local non-patterned area on the surface of the cover plate ensures that the integrity of the surface is guaranteed, which can be obtained by combining any two of the following endpoint values ​​to determine the most effective configuration for particle repulsion: 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%. In addition, this precise distribution between the patterned area and the local non-patterned area ensures an optimal balance between functional surface properties and structural integrity and surface wear resistance.

[0046] According to the present invention, a photovoltaic module includes a cover sheet having a periodic dot structure on at least one surface, preferably on an outer surface. The periodic dot structure is formed so that the cover sheet, particularly its outer surface, transmits electromagnetic radiation having a wavelength greater than 550 nm, preferably greater than 500 nm, and most preferably greater than 450 nm. This is closely related to reducing reflection of incident light (also known as anti-reflection properties). Advantageously, a solar cell panel including a cover sheet according to the present invention exhibits increased power output due to increased insolation.

[0047] The term "interference pixel" (also referred to herein as modified area, e.g. first interference pixel, second interference pixel, third interference pixel and / or further interference pixel) means in the sense of the present invention a periodic pattern or grid of at least three protrusions or inverted protrusions (each as defined herein), preferably at least seven protrusions or inverted protrusions, most preferably at least 19 protrusions or inverted protrusions, which are formed on or in the outer and / or inner surface of the cover plate (see Figure 4 ). The interference pixels are preferably characterized by the fact that the protrusions or inverted protrusions are repeatedly aligned with each other so that each protrusion or inverted protrusion is aligned with its neighboring protrusion or inverted protrusion so that their vertices (in the case of protrusions, their height centers or in the case of inverted protrusions, their depression centers, also called saddle points) are at the same distance from each other (the so-called interference period).

[0048] According to one embodiment of the invention, the cover plate, in particular at least one surface of the cover plate, preferably the outer surface of the cover plate, comprises a plurality of interference pixels, for example first interference pixels, second interference pixels, third interference pixels and / or further interference pixels, wherein the number of interference periods and / or periodic patterns or grids and / or the presence of protrusions or inverted protrusions is different. Preferably, the first interference pixels and the second interference pixels, the third interference pixels and / or the further interference pixels are spaced apart from each other at regular distances. Advantageously, a cover plate comprising such a surface pattern allows the brightness or reflection of light to be reduced, which reduces the impact of undesirable light effects in the housing area.

[0049] According to a preferred embodiment of the present invention, a cover plate, in particular at least one surface of the cover plate, preferably an outer surface of the cover plate, includes a plurality of interference pixels, such as first interference pixels, second interference pixels, third interference pixels, and / or further interference pixels, wherein the interference period and / or periodic pattern or grid and / or the number of protrusions or inverted protrusions present are identical. Preferably, the first interference pixels, the second interference pixels, the third interference pixels, and / or the further interference pixels are spaced at regular intervals from one another. This consistent spacing and structural configuration not only simplifies the manufacturing process, making it more cost-effective and efficient, but also enhances the optical performance of the cover plate. The regular arrangement of the interference pixels ensures uniform distribution of light across the panel, thereby optimizing visual clarity and color fidelity. Furthermore, such an arrangement significantly reduces optical distortion, such as moiré patterns, which can occur when irregular or inconsistent spacing of optical elements interacts with other fine patterns or screens viewed through the cover plate. Thus, by employing a consistent pattern and maintaining precise control over the spatial arrangement of the interference pixels, the present invention provides excellent visual performance and reliability, making it particularly advantageous for applications in high-definition displays and optical devices where the accuracy and quality of the visual output are critical. This facilitates the manufacturing process.

[0050] According to a further embodiment, the first interference pixel and the second interference pixel, the third interference pixel and / or the further interference pixel are spaced apart from each other at irregular distances. This allows for more leeway during production.

[0051] According to a preferred embodiment of the present invention, an interference pixel is a spatial region, preferably on the surface of a substrate, in which the laser (sub)beams directed onto the surface interfere constructively and destructively with each other, thereby forming a pattern of periodically arranged intensity minima and intensity maxima, wherein the shape of the spatial region is circular. By scanning the surface area of ​​the substrate in this manner, i.e., applying multiple interference pixels in such a way that each interference pixel overlaps with its neighboring interference pixels, the surface can be patterned extensively and uniformly. Advantageously, this achieves consistent self-cleaning surface performance.

[0052] According to a further embodiment, the shape of the interference pixel is modified so that it is elliptical. Advantageously, this increases the surface area that can be structured in one spatial direction in one process step.

[0053] For the purposes of the present invention, the term "protrusion" refers to a regularly shaped protrusion from the outer and / or inner surface of the cover plate, particularly in the form of a regularly shaped pyramid, truncated pyramid, cone, or truncated cone. In this regard, multiple elevations can be considered regular twins of one another. The base of the pyramid or truncated pyramid projected onto the outer and / or inner surface of the cover plate can be polygonal. The base of the cone or truncated cone projected onto the outer and / or inner surface of the cover plate can be circular or elliptical. In a particularly preferred embodiment, the protrusion is a "cone", which refers to a structure with a circular, elliptical or polygonal base (relative to the surface of the substrate), in particular a structure with a circular or elliptical base, which is conical or pyramidal, in particular conical, in the vertical direction relative to the surface of the substrate and has a sharp end, a rounded cone end or a truncated cone end, in particular a rounded cone end, in the vertical direction relative to the surface of the substrate, and has a sharp apex, a rounded cone apex or a truncated cone apex, in particular a rounded cone apex, at a saddle point offset from the surface, which saddle point coincides with the point farthest from the surface of the substrate. The height of the structure of the generated pattern is related to the distance between the saddle point (in particular the cone) of the protrusion and the surface of the cover plate. In the context of the present invention, the height-to-diameter ratio or aspect ratio of the protrusion (in particular the cone) is the quotient of the height of the protrusion (in particular the average height of the protrusion) and the diameter of the protrusion.

[0054] In contrast, the term "inverted protrusion" in the context of the present invention refers to a regularly shaped inversion / depression in the surface of the outer and / or inner surface of the cover plate, particularly in the form of a regularly shaped inverted pyramid, inverted truncated pyramid, inverted cone, or inverted truncated cone. In this regard, multiple inverted protrusions can be considered regular twins of one another. The base of the inverted pyramid or inverted truncated pyramid projected onto the surface of the outer and / or inner surface of the cover plate can be polygonal. The base of the inverted cone or inverted truncated cone projected onto the surface of the outer and / or inner surface of the cover plate can be circular or elliptical. In a particularly preferred embodiment, the inverted protrusions are "inverted cones", which refer to structures with a circular, elliptical or polygonal base (based on the surface of the substrate), in particular structures with a circular or elliptical base, which are conical or pyramidal in the vertical direction relative to the surface of the substrate, in particular conical, and have a sharp end, a rounded conical end or a truncated conical end, in particular a rounded conical end, at their saddle point, which coincides with the point farthest from the surface of the substrate. The structural depth of the formed pattern is related to the distance between the saddle point of the inverted protrusion (in particular the inverted cone) and the surface of the cover plate. In the context of the present invention, the height-to-diameter ratio or aspect ratio of the inverted protrusion (in particular the inverted cone) refers to the quotient of the depth of the inverted protrusion (in particular the average depth of the inverted protrusion) and the diameter of the inverted protrusion.

[0055] In the context of the present invention, it is particularly preferred that the lower threshold value of the structural depth of the inverted protrusions or the height of the protrusions (as defined herein) is configured to be equal to or greater than 20 nm, more preferably equal to or greater than 50 nm, most preferably equal to or greater than 100 nm, and in particular equal to or greater than 150 nm or 200 nm. This configuration ensures that the long-term stability of the periodic point structure is improved, protecting them from wear and degradation caused by environmental conditions. The specified depth range may be crucial because it not only contributes to the physical robustness of the structure, but also significantly improves its wear resistance and tear resistance in long-term use. This structural depth standard of the structural components of the present invention significantly improves their durability and functional life, providing significant advantages in applications where environmental exposure and mechanical stress are prevalent. In addition, by specifying a structural depth greater than 200 nm, the present invention effectively solves the common challenges associated with thinner structures, such as rapid degradation and shortened service life, providing a solution that combines durability with excellent performance. The combination of such precisely defined structural depths is directly related to the improvement of the overall reliability and efficiency of technical applications, making the present invention particularly advantageous for use in environments requiring high elasticity and long-term operational stability.

[0056] According to a preferred embodiment, the present invention carefully defines upper thresholds for the structural depth or protrusion height of the inverted protrusions (as defined herein), ensuring that they do not exceed 1,000 nm, particularly not exceed 500 nm, with particular emphasis on a more preferred maximum value of 400 nm, and in particular an optimal upper limit of 300 nm. This careful delineation is established in order to mitigate any potential adverse effects on the light transmission properties of the structure. Exceeding these specified depth thresholds may significantly affect the clarity of the structure, possibly resulting in reduced light transmission, or in more severe cases, causing the cover to appear opaque or milky. Such results are detrimental to applications requiring high levels of light transmission, in which the purity and clarity of light passing through the structure is crucial. By adhering to specific upper limits on the structural depth, the present invention cleverly balances the need for structural integrity and wear resistance with the necessity to maintain optimal light transmission. This balance ensures that the structure remains durable and resistant to environmental wear and tear, while maintaining its transparency and preventing any blurring or diffusion of light, thereby maintaining the aesthetic and functional qualities of the panel or associated optical component. According to a preferred embodiment of the present invention, the structural depth of the inverted protrusions or the height of the protrusions (as defined herein) is within the range of values ​​obtained by combining any two of the following endpoint values: 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1,000 nm. This not only ensures good structural stability / integrity of the modified area including the patterned area and the partially unpatterned area, but also ensures a significant trapping effect, which improves the coupling of light into the photovoltaic module and the coupling of light out of the photovoltaic module, depending on the application and use of the photovoltaic module.

[0057] Furthermore, structures having a structure depth as defined above have been shown to maintain or restore their dust-reducing properties after cleaning the surface, preferably the exterior, of the cover sheet. Due to the advantageously selected structure depth dimensions, their integrity remains stable and their functionality remains intact even after rigorous and repeated cleaning processes. Consequently, the patterned cover sheet according to the present invention is durable over extended periods of use.

[0058] According to a preferred embodiment of the present invention, the cover plate includes a periodic dot structure, such as a first periodic dot structure, a second periodic dot structure, a third periodic dot structure and / or a further periodic dot structure consisting of a surface irregularity / structural element comprising at least three protrusions or inverted protrusions (also referred to herein as a periodic dot structure), wherein the surface irregularity has an aspect ratio of at least 0.001 or at most 0.05, more preferably at least 0.003 or at most 0.03, most preferably at least 0.005 or at most 0.02, and particularly preferably at least 0.007 or at most 0.01. Therefore, the aspect ratio of the dot structure (especially the periodic dot structure) on the outer surface and / or the inner surface of the cover plate is within a range of values ​​obtained by combining any two of the following endpoint values: 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.010, 0.011, 0.012, 0.013, 0.014, 0.015, 0.016, 0.017, 0.018, 0.019, 0.020 , 0.021, 0.022, 0.023, 0.024, 0.025, 0.026, 0.027, 0.028, 0.029, 0.030, 0.031, 0.032, 0.033, 0.034, 0.035, 0.036, 0.037, 0.038, 0.039, 0.040, 0.041, 0.042, 0.043, 0.044, 0.045, 0.046, 0.047, 0.048, 0.049, 0.050. Such aspect ratios change the properties of the surface so that the protrusions or inverted protrusions formed are characterized by having steep sides, thereby hindering the adhesion of particles. Advantageously, such patterns alleviate the accumulation of particles on the surface of the substrate.

[0059] The optical properties are preferably influenced in such a way that a greater proportion of the incident electromagnetic radiation (e.g., visible light) passes through the plane of the substrate, in particular the surface of the substrate. This means that the proportion of electromagnetic radiation that passes through this surface can be increased. Possible structuring increases this proportion due to a change (preferably a gradient) in the refractive index of the substrate, which reduces reflections at the surface. In addition, the applied grating causes a diffraction effect and deflection of the propagation direction of the light (i.e., the electromagnetic wave). This is very advantageous for photovoltaic components and modules because it increases the distance that the light travels within the photovoltaic active layer. As a result, a greater proportion of the incident light can be absorbed and a greater number of charge carriers can be generated, thereby improving the efficiency of the photovoltaic component or module. However, it is also possible to form a structure that increases the proportion of electromagnetic radiation that passes through the surface by multiple reflections within an inverted cone, thereby resulting in a trapping effect, wherein each time an electromagnetic wave hits a point on the surface, in particular within the inverted cone, a further portion of the electromagnetic radiation passes through the surface. The trapping effect is particularly advantageous for thin-film solar cells based on, for example, CdTe.

[0060] According to a preferred embodiment of the present invention, the periodic point structure on the outer surface and / or inner surface of the cover plate comprises inverted protrusions, and optionally the opposite surface (inner surface or outer surface) of the cover plate comprises a periodic point structure formed as protrusions. Thus, a reduction in reflections due to the trapping effect can be advantageously achieved on both the outer surface and the inner surface. A reduction in reflections due to the trapping effect can be achieved when light is decoupled from the outside to the inside, or vice versa, i.e. when light first strikes the outer surface of the cover plate, then passes through the cover plate, and then leaves the cover plate through the inner surface to enter the photovoltaic module. Therefore, this variant is particularly suitable for solar cells or modules, and vice versa, for light-emitting components or modules that generate light (i.e. electromagnetic radiation) within a functional layer.

[0061] The reduction of reflections due to trapping effects (as defined herein) by forming suitable structured and unstructured areas on the outer and / or inner surface of the substrate is very important, in particular for optoelectronically active layers, in particular for optoelectronically active layers in photovoltaic cells, because within these layers, the absorption and / or interaction between electromagnetic radiation entering the optoelectronic component or module and the light-absorbing material in the optoelectronic layer ensures a high efficiency of the optoelectronic component, and / or the interaction between electromagnetic radiation entering the optoelectronic component or module and the light-absorbing material in the optoelectronic layer ensures a high efficiency of the optoelectronic component.

[0062] According to a preferred embodiment of the present invention, the inverted protrusions are unfilled, meaning they do not include a coating or filler composed of a separate filler and / or coating material. Instead, they form a direct interface between the substrate (particularly the cover plate) and the surrounding atmosphere. This reduces the need for additional process steps and coating materials, and creates a surface with a single interface from which light can be reflected. Advantageously, this reduces processing time and costs, and increases the power output of the photovoltaic module due to improved light transmission through the cover plate.

[0063] According to a preferred embodiment of the present invention, modified areas on the outer and / or inner surfaces of the cover plate are selectively coated with a functional layer to enhance their optical properties, particularly by imparting antireflective properties, while also positively impacting a range of other essential properties. This includes imparting hydrophobicity or hydrophilicity to increase self-cleaning capabilities via water repulsion or attraction, enhancing chemical resistance to aggressive environments, and increasing mechanical durability against scratches, abrasion, and wear. This functional coating is preferably applied exclusively to localized and / or all non-patterned areas of the surface, with no coating applied to the inverted protrusions to maintain their structural integrity and intended functionality. However, for larger structural elements (periodic dot structures) within the inverted protrusions, it is conceivable that their outer walls could be provided with a coating. In such cases, the coating is carefully designed to be extremely thin, with a maximum thickness in the range of 50 to 200 nm, ensuring that the inverted protrusions remain essentially "unfilled," thereby maintaining their protrusions. This selective application of the functional coating optimizes the overall performance of the photovoltaic module, particularly its optical performance, by reducing reflectivity without compromising the structural features of the patterned areas that are critical to the cover plate's self-cleaning and light management capabilities.

[0064] In the context of the present invention, surfaces can be selectively modified to tailor optical properties and enhance functional performance by applying specific coatings. Silicon dioxide (SiO2) and titanium dioxide (TiO2) thin film oxide coatings are used for their excellent anti-reflective and hydrophilic properties, which significantly improve light transmission while facilitating self-cleaning by facilitating the diffusion of water, thereby facilitating the removal of surface contaminants. Fluoropolymer coatings are used for their unparalleled hydrophobic and oleophobic properties, making the surface repellent to water, oil, and various other liquids, thereby simplifying maintenance and extending the life of the equipment.

[0065] Additionally, metal nanocoatings such as gold (Au) or silver (Ag) are applied in ultrathin layers to provide electrical conductivity or selectively reflect certain wavelengths of light. This adaptability is crucial in applications requiring precise control of electrical properties or thermal management. Titanium dioxide (TiO2)-based photocatalytic coatings are activated by ultraviolet light, generating reactive oxygen species that effectively decompose organic pollutants and eradicate microorganisms on the coating surface, providing superior cleanliness and reducing potential biohazards.

[0066] Dielectric and interference coatings are designed to reflect or transmit specific wavelengths of light, enabling color customization and improving the efficiency of photovoltaic modules such as solar cells. This technology not only enables the creation of aesthetically pleasing surfaces, but also optimizes energy harvesting and light management.

[0067] These coating materials and their application methods provide a comprehensive approach to modifying surface properties to improve the performance of photovoltaic modules under various conditions. The strategic implementation of these coatings by the present invention ensures maximum optical efficiency, durability and versatility, making them a highly beneficial solution for the advancement of photovoltaic technology.

[0068] Chemical vapor deposition (CVD) coatings are an integral part of the present invention for depositing high-quality, high-performance thin films on the surface of substrates. The use of CVD processes allows for precise control of the thickness and composition of the deposited coating, thereby enabling surface functionalization with enhanced optical, electrical, and physical properties. CVD technology facilitates the deposition of a wide variety of materials, including advanced ceramics, metals, and polymer coatings, which can be customized to specific application requirements.

[0069] Incorporating CVD coatings into this invention significantly increases the substrate's resistance to environmental degradation, including corrosion, abrasion, and UV damage, thereby extending the operational life of optoelectronic devices. Furthermore, CVD coatings can be designed to enhance the surface's anti-reflective properties, optimizing light absorption and reducing unwanted reflections, which is crucial for devices such as solar cell panels and optical sensors. The process can also be used to create surfaces with specialized properties, such as hydrophobicity or hydrophilicity, resulting in enhanced self-cleaning properties and reduced maintenance requirements.

[0070] The versatility and adaptability of CVD coatings offer significant advantages in the manufacture of optoelectronic devices, providing a method for achieving excellent performance characteristics while maintaining cost-effective and scalable production. The strategic application of CVD coatings achieves a harmonious balance between functionality and durability, ensuring that photovoltaic modules remain efficient and reliable under a variety of operating conditions.

[0071] According to one embodiment of the invention, the cover plate comprises a further surface pattern, in particular a wave pattern, which is formed during the patterning process, i.e., when a laser pulse is irradiated on the substrate to be patterned due to the presence of a high-intensity zone, the patterning being achieved by means of a self-organization process, which is stimulated by at least partial melting of the substrate material by the laser pulse in the high-intensity zone. In particular, the wave structure is generated by utilizing a laser-induced periodic surface structure (LIPSS). The wave pattern preferably exhibits quasi-periodic properties, i.e., a regular arrangement of structural features or structural defects with small deviations in distance, and is characterized in that its wave peaks are arranged at a distance from one another that corresponds to the structural period, the distance being in the range of 20 nm to 5 μm, preferably in the range of 100 nm to 1000 nm, more preferably in the range of 100 nm to 800 nm, most preferably in the range of 100 nm to 600 nm, and in particular in the range of 100 nm to 400 nm. As described above, the LIPSS can be formed directly on the surface of the cover plate or can be superimposed on the inverted protrusions. Advantageously, they increase the self-cleaning properties of the surface.

[0072] Self-cleaning performance

[0073] The water contact angle is a measure of a substrate's hydrophobicity or hydrophilicity. It is determined by droplet shape analysis, measuring the wetting angle of a water droplet deposited on the substrate's surface. Water contact angles greater than 90° are associated with hydrophobic properties, while water contact angles less than 90° are associated with hydrophilic properties. Hydrophobic properties refer to a surface's tendency to repel water, meaning it allows water to roll off the surface without puddling or leaving behind wet marks. Hydrophilic properties are characterized by water spreading over the surface in such a way that it forms a thin film covering a large portion of the surface area.

[0074] Hydrophobic surface properties are associated with self-cleaning properties. Due to the water-repellent properties of such surfaces, dirt and dust particles carried by water do not accumulate on the surface. Furthermore, water droplets rolling off the surface due to its hydrophobic properties carry dirt and dust particles in their path. Using such hydrophobic surfaces is advantageous in the field of optoelectronic devices because it helps maintain surface transparency, particularly on the exterior surfaces of optoelectronic device covers, thereby allowing light to transmit at a higher rate and improving device efficiency.

[0075] Hydrophilic surface properties are also associated with self-cleaning properties. Due to the water-absorbing properties of such surfaces, the thin film formed by water impinging on the surface helps prevent dirt and dust particles from strongly adhering to the surface, thereby facilitating their removal. The use of such hydrophilic surfaces is advantageous in the field of optoelectronic devices because it helps maintain the transparency of the surface, especially the transparency of the outer surface of the optoelectronic device cover, thereby allowing light to be transmitted at a higher rate and improving the efficiency of the device. In general, the surfaces made of glass patterned by the methods disclosed herein are characterized by their hydrophilicity, thereby allowing good wetting properties when in contact with water.

[0076] According to the present invention, if the water contact angle of the surface is less than 20° or greater than 130°, preferably less than 10° or greater than 140°, and particularly preferably less than 5° or greater than 150° when wetted with water, preferably deionized water, then the surface has self-cleaning properties. This specification utilizes the phenomena of superhydrophobicity and superhydrophilicity to significantly reduce the accumulation of dust and dirt, thereby maintaining the cleanliness and operating efficiency of the surface without the need for frequent manual cleaning. In addition, a surface with such an extreme water contact angle can promote rapid drainage, thereby effectively removing pollutants, thereby increasing the durability and service life of the equipment. This feature also helps to maintain optimal light transmission and reduce maintenance costs, making it particularly advantageous for outdoor or harsh environment applications.

[0077] Additionally, a substrate having self-cleaning surface properties may allow for easier cleaning. Preferably, the substrate has hydrophobic properties, wherein air (preferably airflow) or water for cleaning purposes easily rolls off the surface, thereby making a drying process unnecessary.

[0078] According to the present invention, another aspect of the self-cleaning surface properties relates to the adhesion of dirt and / or dust particles to the surface of the substrate, which is mainly determined by the van der Waals forces acting between the two. However, the inventors have observed that the van der Waals forces are reduced for particles whose average particle size is larger than the interference period of the periodic dot structure formed on the surface of the substrate, as defined herein. Therefore, the surface formed by patterned and non-patterned areas comprising a periodic dot structure with a sufficiently small structural period allows for reduced adhesion of dust and / or dirt particles and thus exhibits anti-fouling properties, referred to herein as anti-fouling properties. This advantageously ensures the transparency of the surface even under harmful environmental conditions, such as dusty and / or dirty environments.

[0079] Particularly problematic for photovoltaic modules, where surface transparency is crucial, are small particles (such as dust) that adhere firmly to the surface. This applies in particular to dust particles with diameters between 0.2 μm and 100 μm, more particularly between 0.5 μm and 50 μm, and especially between 1 μm and 25 μm. These particles reduce surface transparency, thereby lowering the efficiency of the photovoltaic module, particularly the photovoltaic cells, and affecting the light incidence angle at which the photovoltaic cells operate most efficiently.

[0080] According to an advantageous embodiment, the cover plate of the photovoltaic module includes a patterned area comprising a first periodic dot structure or a periodic line structure or a hierarchical structure consisting of superimposed periodic and / or quasi-periodic structures (also referred to herein as LIPSS), wherein these periodic and / or quasi-periodic structures have an interference period or half of an interference period or size of the structural elements (periodic line structures) of less than 100 μm, preferably less than 20 μm, and most preferably less than 10 μm. According to a particularly preferred embodiment, the interference period or half of an interference period or size of the structural elements (periodic line structures) is in the range of 50 nm to 5 μm. As a result, the adhesion of small dust and / or dirt particles, in particular dust and / or dirt particles with a particle size greater than 20 μm, in particular greater than 12 μm, and in particular greater than 6 μm, to the surface of the cover plate is significantly reduced, in particular compared to an unpatterned substrate. In contrast, the average particle size of the particles that adhere to the surface is less than 20 μm, preferably less than 12 μm, and more preferably less than 6 μm. As a result, the force required to remove these particles from the surface (such as that provided by a small airflow near the surface) is significantly reduced. This characteristic substantially increases the performance of photovoltaic modules while reducing the need for frequent cleaning and maintenance, providing profound advantages in terms of operational efficiency and cost-effectiveness. This allows photovoltaic modules to have higher power output and reduces cleaning and maintenance costs.

[0081] According to one embodiment of the present invention, a cover panel, preferably its outer surface, includes a periodic dot structure, wherein the periodic dot structure has a structural period corresponding to an interference period of less than 100 μm, preferably less than 20 μm, and most preferably less than 10 μm. This allows for efficient manipulation of light at the surface level, thereby improving anti-reflection performance and enhancing visual clarity under various lighting conditions. Superimposed on the periodic dot structure is a quasi-periodic wave structure, as defined herein, wherein the quasi-periodic wave structure has a structural period of 20 nm to 5 μm. The integration of the quasi-periodic wave structure further facilitates diffuse scattering of incident light, thereby providing a uniform light distribution across the surface, significantly reducing glare and enhancing the user's visual experience. Preferably, the periodic dot structure and the quasi-periodic wave structure are formed during the same process step, thereby making production less time-consuming and therefore more economical. This synchronized production process not only maximizes production efficiency but also ensures a high degree of uniformity and consistency across the panel surface, contributing to overall product reliability and quality. Advantageously, such a cover panel, as defined herein, exhibits at least a 50% reduction in dust adhesion. This significant reduction in dust pickup minimizes the frequency of cleaning required to maintain optimal performance and appearance, increasing the economic and practical benefits of the present invention.

[0082] According to a preferred embodiment of the present invention, the cover plate, preferably the outer surface of the cover plate, includes at least one local patterned area and a local non-patterned area, which constitute at least one modified area as defined herein. In addition, the substrate includes all non-patterned areas, which constitute at least 50% of the outer surface of the cover plate. In this embodiment, the outer surface of the cover plate (particularly in the patterned area) has reduced dust adhesion. Due to the reduced dust adhesion in at least one modified area, contaminant particles tend to move across the surface because they cannot adhere to at least one modified area and carry away particles deposited on the surface in all non-patterned areas on their path. Advantageously, this leads to reduced dust adhesion and a lower contamination rate on the entire outer surface of the cover plate. In addition, the presence of local non-patterned areas within the patterned area has advantages over conventional structuring, in which each structure, especially each periodic point structure, is separated from the next structure only by a wall (which in turn represents a large number of attack points). Due to the local non-patterned areas, higher structural integrity is guaranteed because there are fewer attack points affected by the external environment per unit area.

[0083] According to a further embodiment of the present invention, the cover plate, preferably the outer surface of the cover plate, includes at least one locally patterned area and a locally unpatterned area, which constitute at least one modified area as defined herein. In addition, the substrate includes all unpatterned areas, and the all unpatterned areas constitute at least 50% of the outer surface of the cover plate. In this embodiment, at least one modified area is formed by means of direct laser interference patterning. This technology allows for precise control of the patterning process, thereby producing a highly defined quasi-periodic wave structure that enhances the functional and aesthetic properties of the cover plate. Due to the irradiation of the surface of the cover plate, a quasi-periodic wave structure is partially formed in all unpatterned areas caused by the self-organization process, wherein the quasi-periodic wave structure has a structural period of 20nm to 5m, preferably in the range of 100nm to 1,000nm, more preferably in the range of 100nm to 800nm, most preferably in the range of 100nm to 600nm, and in particular 100nm to 400nm. The quasi-periodic wave structure (also referred to herein as LIPSS) preferably constitutes at least 20% of the total non-patterned area, more preferably at least 40% of the total non-patterned area, and most preferably at least 60% of the total non-patterned area. This ratio significantly contributes to the cover plate's effective reduction of particle adhesion, in particular environmental dust and pollutants, thereby maintaining the transparency and performance of the panel over time. Due to the small structural period of the quasi-periodic wave structure, particles having a size significantly larger than the structural period, in particular particles with an average particle size between 3 μm and 30 μm, cannot adhere to the surface comprising the quasi-periodic wave structure. This selectivity of particle adhesion not only provides a cleaner surface, but also improves the optical efficiency of the panel by minimizing light scattering and absorption caused by dust accumulation. Advantageously, a reduction in dust adhesion and a reduction in contamination rate can therefore be achieved.

[0084] In order to quantify the dust resistance of the substrate surface, it is necessary to measure the dust adhesion. According to the present invention, the dust adhesion measurement includes the following steps:

[0085] Cover the substrate surface with dust to a coverage of 15% of the surface area,

[0086] Use 10m / s air flow to clean the surface.

[0087] Measure the remaining dust coverage on the surface.

[0088] Preferably, the measurement is performed at an ambient temperature of 21° C. The temperature of the substrate is preferably consistent with the ambient temperature. Preferably, the measurement is performed at a relative humidity of 60%.

[0089] According to the present invention, the dust adhesion reduction rate (DAR) is a measure of the change in the retained dust coverage ratio (DCR) on a substrate surface when comparing a non-patterned surface to a patterned surface. The retained dust coverage ratio is measured according to a dust adhesion measurement method, as described herein, wherein the dust coverage ratios of both patterned and non-patterned substrates are determined, and the dust adhesion reduction rate is calculated as:

[0090]

[0091] According to the present invention, dust adhesion on the substrate surface is reduced by more than 50%, preferably more than 55%, more preferably more than 60%, and most preferably more than 63%. Initial coverage is determined at 15% of the surface area, followed by cleaning with a 10 m / s airflow. This significant reduction in dust adhesion not only minimizes the frequency and need for cleaning but also improves optical performance by maintaining a clear, unobstructed surface. Consequently, dust accumulation on the photovoltaic module surface is significantly reduced, ensuring long-term module functionality and reducing the need for maintenance and cleaning. Furthermore, by ensuring long-term module functionality with reduced maintenance and cleaning, operating costs are significantly reduced and the environmental impact of frequent cleaning is minimized.

[0092] According to the present invention, the dust removal rate (DRR) is a measure of how much dust is removed from the substrate surface when performing the dust adhesion measurement described herein. The DRR is calculated as:

[0093]

[0094] In this article, DC 测量后 Corresponding to the dust coverage of the substrate surface after cleaning the substrate surface with the above airflow, DC 测量前 Corresponds to the dust coverage of the substrate surface before cleaning. According to the present invention, the DRR of the substrate surface is at least 75%, preferably at least 80%, more preferably at least 85%, and most preferably at least 90%. A high dust removal rate is desirable because it indicates that dust on the surface can be easily removed without the need for additional cleaning, for example, due to wind or other weather phenomena, and can substantially restore the higher power output of the photovoltaic device without requiring additional labor. An initial coverage of 15% of the surface area is determined, and then cleaning is performed using an airflow of 10 m / s.

[0095] According to the IEC 61724-1 technical standard, the soiling rate (SR) of photovoltaic modules (especially solar cells) is defined as:

[0096]

[0097] From the definition, it can be seen that the range of the fouling rate is from 1 (no fouling) to 0 (complete loss of power output due to fouling). According to this definition, the fouling loss (SL) can be defined as:

[0098] SL=1-SR

[0099] The dirt deposition rate, or dirt rate, is defined as the rate of change in dirt loss, expressed in % per day. Depending on the location of the photovoltaic modules and specific weather conditions, it can range from 0.001% per day to 0.5% per day. For example, in temperate climates, where weather is generally mild and precipitation, wind, and airborne particulate matter (e.g., dust and / or pollution) are moderate, the dirt rate is typically between 0.01% and 0.1% per day. In dusty climates, where airborne particulate matter levels are high, the dirt rate tends to be higher, ranging from 0.05% to 0.5% per day. Conversely, in rainy or humid climates, where precipitation helps reduce dust accumulation, the dirt rate is generally lower, typically between 0.001% and 0.01% per day. The present invention therefore reduces these rates, resulting in up to 50% reduction in contamination rates in both temperate and rainy or humid climates, resulting in contamination rates of 0.005% to 0.05% per day in temperate climates and 0.0005% to 0.005% per day in rainy or humid climates. In dusty climates, dust levels can even be reduced by up to 70%, resulting in contamination rates from 0.015% to 0.15% per day. Consequently, the efficiency of photovoltaic modules can be advantageously increased, particularly in terms of power output, by up to 25%.

[0100] Similar to the dirtiness rate, the dust deposition rate refers to the change in the amount of dust deposited on the surface of the photovoltaic module within a day, and the unit is g / m 2 Depending on the specific climatic conditions, the dust deposition rate can reach up to 15%. The particle size and wind speed are particularly important for the dust deposition rate.

[0101] Direct laser interference patterning method and device

[0102] The present invention also relates to a method for producing patterned areas by direct laser interference patterning (DLIP). Direct laser interference patterning refers to a method for forming precise micrometer-scale and nanometer-scale structures on the surface of a substrate by interfering laser (sub) beams, which are directed to the substrate surface in such a way that they constructively and destructively interfere with each other within the interference area to form areas of high and low energy (laser) intensity, which are regularly arranged, in particular periodically repeated or simply periodically arranged. In the high-intensity area (also referred to as the area with the maximum energy), the substrate material is removed from the surface, leaving surface irregularities, in particular surface indentations, as described herein. In the low-intensity area (also referred to as the area with the minimum energy), the substrate material remains unchanged. Thus, a periodic surface pattern can be formed within the interference area and the periodic surface pattern can be gradually reformed over the entire surface of the substrate by redirecting the interfering laser (sub) beams to different parts of the substrate surface. A single interference area irradiated in one step forms an interference pixel, as defined herein. Apparatus for performing DLIP is known in the art (see, for example, PCT / EP2022 / 068490) and typically comprises a large number of optical elements, preferably consisting primarily of lenses and prisms. As described herein, such apparatus is preferably used to perform DLIP to form a patterned area on a cover substrate surface.

[0103] According to the present invention, in order to form a patterned area on the surface of a cover plate, a DLIP device is used, which includes at least one beam splitter element, which is configured to split an incident laser beam into at least three sub-beams. These sub-beams are further directed onto the surface of the cover plate in such a way that they constructively and destructively interfere with each other. The interference pixels thus generated are characterized by a first interference period (p1), which can be continuously adjusted by displacement of the beam splitter element (2), while the other optical elements included in the DLIP device are preferably kept fixed. This allows the interference period and the resulting patterned area to be easily adjusted without having to reconfigure the entire device setup, thereby achieving a cost-effective and time-saving production process.

[0104] According to the invention, the patterning of the cover plate (in particular the outer surface of the cover plate) is carried out directly. In the present invention, "directly" means that the laser (sub) beams constructively and destructively interfere in an area of ​​the cover plate surface using the DLIP method described in the present invention, and this area is the interference pixel. The resulting pattern of intensity minima and intensity maxima directly corresponds to the periodic dot pattern described in claim 1, so that the cover plate has self-cleaning surface properties. Advantageously, since any patterning process is carried out directly on the respective substrate material of the cover plate, a mask layer or coating can be omitted. More advantageously, this process can be used to make cover plates using a variety of materials, since it is also applicable to glass, metal, polymers and ceramics.

[0105] According to a preferred embodiment of the present invention, the DLIP device includes a polygon scanner. In this embodiment, at least one optical element includes a periodically rotating prism, preferably a periodically rotating mirror prism, in particular a polygon mirror or a polygon wheel, and includes a focusing element, which is arranged downstream of the periodically rotating prism in the optical path. The focusing element is configured so that when the laser (sub) beam passes through the focusing element, interference occurs on the substrate surface within the interference area. The optical element preferably also includes at least one deflection element, such as a reflective deflection element, for deflecting the laser (sub) beam in the optical path. At least one further deflection element can be arranged upstream and / or downstream of the periodically rotating prism in the optical path. At least one further deflection element is arranged upstream of the focusing element in the optical path. Such an arrangement is conducive to rapid scanning of the substrate surface, thereby achieving up to 3m 2 / min high structuring rate, especially at 0.05m 2 / min to 2m 2 / min, particularly preferably within the range of 0.1m 2 / min to 1m 2 / min, most preferably in the first 0.1m 2 / min to 0.9m 2 The specific structuring rate depends in particular on the available laser power.

[0106] According to another embodiment of the present invention, the present invention relates to an apparatus for performing direct laser writing (DLW) or a DLW apparatus. Direct laser writing is a technology for the precise manufacture and patterning of micron- and nanometer-scale materials. Its basic operating principle is to focus a laser beam onto a substrate, causing local physical changes, especially the removal of material. By precisely controlling the laser intensity and the scanning pattern, complex structures and patterns can be written directly into the material with high resolution and high precision. Advantageously, this arrangement simplifies the manufacturing process and eliminates the need for a large number of optical elements, especially beam splitter elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0107] The present invention is explained in more detail with reference to the following figures and examples, but the present invention is not limited thereto.

[0108] It shows:

[0109] Figure 1 A photovoltaic module comprising two photovoltaic cells sealed by a cover plate.

[0110] Figure 2 . Schematic cross-section of a photovoltaic module with a pattern on the outer surface of the cover.

[0111] Figure 3A.Schematic diagram of the inverted protrusion.

[0112] Figure 3B Schematic diagram of an inverted protrusion-like structure with surface irregularities.

[0113] Figure 4 . Schematic diagram of interference pixels of width D generated on the surface of the cover plate and the distribution of the individual interference pixels on the surface of the cover plate, wherein the interference pixels are shifted relative to each other with a pixel density Pd.

[0114] Figure 5 .Visualization of water contact angle.

[0115] Figure 6. Schematic diagram of quasi-periodic wave structure in the submicron range

[0116] A) Top view, and

[0117] B) Cross-sectional view.

[0118] Figure 7 . Schematic diagram of interference pixels of width D formed on the surface of the cover plate and the distribution of each interference pixel on the surface of the cover plate, wherein the interference pixels are shifted relative to each other at a pixel density Pd to form a completely non-patterned area between each interference pixel. DETAILED DESCRIPTION

[0119] Figure 1 A photovoltaic module (1) is shown having a number of photovoltaic cells (2). The photovoltaic cells (2) are electrically connected to one another, and at least some of the photovoltaic cells (2) are connected in series to increase the generated voltage. The outer surface (4) of the cover plate (3) is provided with an inverted protrusion (7), which is designed as a sealing cover to protect all photovoltaic cells (2) arranged on the module (1) from environmental influences (e.g., moisture). The inverted protrusions (7) arranged on the outer surface (4) form a patterned area (10), while the local non-patterned area (11) is a portion of the surface without structure, in particular a portion of the surface without the inverted protrusion (7). In this way, the surface of the cover plate (3) (in particular the outer surface (4)) is completely divided into a patterned area (10) and a non-patterned area (11).

[0120] Figure 2 A schematic cross-sectional view of a photovoltaic module is shown to intuitively illustrate the reduction in reflection caused by the trap effect. A cover plate (3) formed as a sealing substrate is shown, with the cover plate facing upward. A functional layer (6) adjacent to the cover plate (3) is shown below. The cover plate (3) has an outer surface (4) and an inner surface (5), the outer surface being away from the functional layer (6) adjacent to the cover plate (3). The inner surface (5) of the cover plate (3) faces the functional layer (6) adjacent to the cover plate (3), i.e., is directly adjacent to the functional layer (6).

[0121] The outer surface (4) of the cover plate (3) has inverted protrusions (7), and the cross-section is straight in a row of inverted protrusions (7). Light (9) incident on the outer surface (4) will also partially illuminate an interface point arranged in the inverted protrusions (7). At this interface point, a portion of the light (9) has been transmitted through the interface to the interior of the cover plate (3). However, another portion of the light (9) is reflected and illuminates another interface point 45 arranged in the inverted protrusions (7). Here, a portion of the light (9) is also transmitted through the interface between the cover plate (3) and the adjacent layer, and a smaller portion is reflected. In this embodiment, this reflected portion also reaches another interface point, where a portion of the light (9) is also transmitted. Therefore, compared with the outer surface (4) without the inverted protrusions (7), the total amount of light (9.1) transmitted through the interface is significantly increased.

[0122] Figure 3A A schematic representation of an inverted protrusion (7) generated by a laser interferometric method is shown, the structural depth of the protrusion being x. The base region (12) of the inverted protrusion (7) is circular with a diameter d. The side surface (13) is smooth.

[0123] Figure 3B A schematic diagram of a protrusion-like indentation (7) is shown, which can be produced, for example, by an etching process using a mask with circular openings (not shown here). Although the base region (12) is shown to be circular, the side surface (13) is irregularly shaped.

[0124] Figure 4 A schematic diagram contains interference pixels of width D generated on the surface of the cover plate and the distribution of the individual interference pixels on the surface of the cover plate, wherein the interference pixels are displaced relative to each other by a pixel density Pd.

[0125] In this embodiment, the pixel density Pd is smaller than the interference pixel width D. Thus, by moving the cover plate (3), a broad uniform periodic dot structure can be generated on the surface of the cover plate by the pulsed laser beam, preferably a broad and / or transparent cover plate.

[0126] Preferably, the interference pixels applied one after the other are arranged adjacent to each other. In this embodiment, there is an overlap between two interference pixels arranged adjacent to each other. Due to the multiple illumination, self-organization processes are preferably stimulated within the patterned area, i.e. within the inverted protrusions (7). This allows for the efficient generation of layered structures.

[0127] Figure 5A visualization of the water contact angle (14) is shown. Water (15) is arranged here in the form of a droplet on a substrate (3). Outside the water droplet (15), air is present in the gas phase. The water contact angle (14) is the angle between the surface of the substrate (3) and a tangent line (16) adjacent to the water droplet (15). The tangent line (16) is considered to be in contact with the surface of the substrate (3). To determine the water contact angle (14), it is usually necessary to take a shadowgraph of the water droplet (15).

[0128] Figure 6A Visualize the quasi-periodic wave structure (17) in a plan view, Figure 6B is a cross-sectional view comprising a patterned substrate that can be fabricated by the methods disclosed herein, particularly by multiple irradiation or high-intensity single irradiation. Figure 6B The cross-sectional view shows Figure 6A The structure shown is a cross-section taken approximately along section line AA. The self-organization processes occurring in the material lead to the formation of a wave-like structure with peaks (18) and troughs (19) in the area irradiated in this manner. Although defects (20), i.e., irregularities, may also occur, the resulting structure generally exhibits a certain periodicity. Therefore, compared to a truly periodic structure, this structure exhibits both deviations in the structural dimensions, especially the distances between the peaks and troughs, and defects, resulting in a non-uniform wave structure.

[0129] Figure 7 A schematic diagram shows interference pixels of width D formed on the surface of the cover plate and the distribution of the individual interference pixels on the surface of the cover plate, wherein the interference pixels are shifted relative to each other at a pixel density Pd.

[0130] In this embodiment, the pixel density Pd is greater than the width D of the interference pixel. Therefore, by moving the cover plate (3), its surface can be extensively patterned by the pulsed laser beam while ignoring certain areas of the cover plate surface. This creates a completely non-patterned area in which the characteristics of the cover plate remain unchanged compared to the non-patterned cover plate. The outline of the interference pixel is drawn with a dotted line for illustration. On the substrate surface, no demarcation lines are visible at the boundaries of the interference pixels, and no other changes are visible on the surface of the substrate showing the dotted lines.

[0131] Reference Signs List

[0132] 1 Photovoltaic module

[0133] 2 Photovoltaic cells

[0134] 3 Cover / Base

[0135] 4 External surface

[0136] 5 Inner surface

[0137] 6 Functional Layer

[0138] 7 Structural support / connection layer

[0139] 8 Inverted protrusion

[0140] 9 Incident Light

[0141] 9.1 Transmitted Incident Light

[0142] 9.2 Reflected / Captured Incident Light

[0143] 10 Patterned area

[0144] 11 Local non-patterned area

[0145] 11.1 All non-patterned areas

[0146] 12 Base region

[0147] 13 side surface

[0148] 14 Water contact angle

[0149] 15 Water Drop

[0150] 16 Tangent

[0151] 17 Quasi-periodic wave structure

[0152] 18 Crest

[0153] 19 Trough

[0154] 20 Defects

[0155] 21 Interference pixels / modified areas

[0156] AA cutting line

[0157] D is the diameter of the interference pixel.

[0158] Pd pixel density

[0159] d Diameter of the inverted protrusion

[0160] x structure depth

Claims

1. A photovoltaic module (1), comprising: A cover plate (3) having self-cleaning surface properties, the cover plate (3) having an outer surface (4) and an inner surface (5), Wherein, the cover plate (3) is at least partially transparent, The outer surface (4) and / or the inner surface (5) comprises a modified region, the modified region comprising a patterned region (10) and a local non-patterned region (11), wherein the patterned region (10) is formed by a first periodic dot-shaped structure, and the first periodic dot-shaped structure is formed by at least one first interference pixel (21) having a first interference period (p1), wherein the first interference pixel (21) comprises a periodic array of at least three regularly shaped protrusions (8) or inverted protrusions (8), It is characterized in that The interference period (p1) of the first periodic dot structure is in the range of 50 nm to 50 μm, The patterned cover plate, in particular the patterned outer surface, has a dust adhesion reduction rate of at least 40% compared to the non-patterned cover plate, in particular compared to the non-patterned outer surface, The condition is that the average particle size of the contaminants is less than 50 μm.

2. The photovoltaic module according to claim 1, wherein: The dust removal rate of the cover plate, especially the outer surface thereof, is greater than 75%.

3. The photovoltaic module according to claim 1, wherein: The cover plate, in particular the outer surface thereof, has a reduced dust accumulation rate, wherein the dust accumulation rate is reduced by at least 50% compared to the non-patterned surface.

4. The photovoltaic module according to claim 1, wherein: The cover plate, especially the outer surface thereof, has a daily soiling rate of less than 0.15% under dusty climate conditions.

5. The photovoltaic module according to claim 1, wherein: The cover plate, especially the outer surface thereof, has a daily soiling rate of less than 0.05% under temperate climate conditions. The photovoltaic module according to claim 1 , wherein: The cover plate, in particular the outer surface (4) thereof, has a water contact angle of less than 20° or greater than 130°.

7. The photovoltaic module according to claim 1, wherein: The protrusion or inverted protrusion of the first interference pixel has a structure height or depth, and wherein the statistical average value d of the structure height or depth is 50 In the range of 10 nm to 1,000 nm, in particular in the range of 10 nm to 500 nm, particularly preferably in the range of 50 nm to 400 nm, very particularly preferably in the range of 75 nm to 250 nm.

8. The photovoltaic module according to claim 4, wherein: The maximum structure depth is 1 μm.

9. The photovoltaic module according to claim 1, wherein: The aspect ratio of the first periodic dot-like structure is at least 0.001 or at most 0.

05.

10. The photovoltaic module according to claim 1, wherein: The periodic dot-shaped structure is formed such that the wavelength of electromagnetic radiation emitted by the cover plate, in particular the outer surface thereof, is greater than 550 nm, preferably greater than 500 nm, and most preferably greater than 450 nm.

11. The photovoltaic module according to claim 1, wherein: The inner surface and / or the outer surface of the cover plate, in particular the outer surface thereof, comprises a non-patterned area accounting for at least 50% of the total surface area.

12. A method for manufacturing the photovoltaic module according to claim 1, comprising the following steps: S01, providing a first cover plate having an inner surface and an outer surface, S02, generating a modified region on at least one surface of the cover plate, S03, applying a functional layer, preferably comprising or consisting of a photovoltaic material, The modified region includes a patterned region and a local non-patterned region, the patterned region includes at least one first periodic dot-shaped structure, and the first periodic dot-shaped structure is formed by at least one first interference pixel having at least one first interference period (p1). The interference period (p1) of the first periodic dot structure is in the range of 50 nm to 50 μm, The dust adhesion of the cover plate, especially the outer surface, is reduced by at least 55%, Among them, the average particle size of the pollution particles is less than 20μm.

13. The method according to claim 7, wherein: The patterned area is produced by direct laser interference patterning, wherein the sub-beams are generated by splitting an incident laser beam into at least three sub-beams by a beam splitter element (2), and wherein the first interference period (p1) of the first interference pixel is continuously adjusted by displacement of the beam splitter element (2), wherein, preferably, the further optical element is fixed.

14. The method according to claim 8, wherein The first interference pixels are reproduced on at least one surface of the cover plate using a polygon scanner.

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