RU2472251C2 - Photoelectric cells with treated surfaces and use thereof - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: photoelectric cell according to the invention has a monolithic unit of a plurality of semiconductor photoelectric cells, each having at least one p-type or n-type diffusion doped region; a structured dielectric coating applied on at least one p-type or n-type diffusion doped region, wherein structures on said structured dielectric coating reduce the contact area between the metal layer and the doped regions in order to reduce recombination loss of photogenerated carriers in the plurality of semiconductor photoelectric cells; and a metal layer lying on the boundary surface between cells in the plurality of semiconductor photoelectric cells. A method of producing photoelectric cells with reduced recombination loss of photogenerated carriers is also disclosed.

EFFECT: efficiency of conversion.

22 cl, 27 dwg

Description

Cross reference to related applications

This application claims priority for a provisional US application with serial number 61 / 089,389, filed August 15, 2008 and entitled "SUNNY ELEMENT WITH STRUCTURED CONTACTS", which claims priority for a US patent application with serial number 12 / 535,952, entitled "PHOTOELECTRIC TEXTURED CONTACTS ”, filed August 5, 2009; U.S. Patent Application Serial Number 12 / 536,982, filed August 6, 2009, entitled "MULTI-TRANSITION ELEMENT WITH VERTICAL TRANSITIONS WITH A TEXTURED SURFACE," which claims priority for provisional US application Serial Number 61 / 088,921, filed August 14, 2008, entitled “MULTI-TRANSITION ELEMENT WITH VERTICAL TRANSITIONS WITH A TEXTURED SURFACE”; US Patent Application Serial Number 12 / 536,987, filed August 6, 2009, entitled “PHOTOELECTRIC ELEMENT WITH BUFFER ZONE”, which claims priority on US provisional application Serial Number 61 / 088,936, filed August 14, 2008, entitled “SUNNY” ELEMENT WITH BUFFER ZONE ”; and U.S. Patent Application Serial Number 12 / 536,992, filed August 6, 2009, entitled "ELECTROLYZES BY MULTI-TRANSITION PHOTO-ELECTRIC ELEMENTS WITH VERTICAL TRANSITIONS," which claims priority for a provisional US application with serial number 61 / 092,531 2008 entitled “ELECTROLYSIS BY MEANS OF MULTI-TRANSITION PHOTOELECTRIC CELL WITH VERTICAL TRANSITIONS”. The contents of the above applications in full are hereby incorporated by reference.

State of the art

The limited supply and increasing demand for fossil fuels and the resulting environmental damage on a global scale have led to universal efforts to diversify the sources of energy used and related technologies. One such source is solar energy, which utilizes photovoltaic (PV) technology to convert light into electricity. In addition, solar energy can be used to generate heat (for example, in solar furnaces, steam generators and the like). Solar technology is usually carried out using a series of PV elements or solar cells, or their panels, which absorb sunlight and convert sunlight into electricity, which can then be transferred to the electric power system. Significant progress has been made in the development and production of solar cell panels, which has effectively increased efficiency while reducing the cost of their production. With the development of more highly efficient solar cells, the size of the cells decreases, which leads to an increase in the feasibility of using solar cell panels to provide competitive renewable energy-based replacements for depleted and highly demanded non-renewable resources. To this end, systems for collecting solar energy, such as a solar energy concentrator, can be deployed to convert solar energy into electricity, which can be transferred to electrical networks, and also to collect heat. In addition to the development of technology for solar energy concentrators, the aim was to improve solar cells aimed at their use in solar energy concentrators.

The technology of solar cells for converting high-intensity radiation, called multi-junction (VMJ) solar cells, is an integrally connected series-connected structure of miniature individual cells with vertical transitions, which is illuminated from the edges, with electrical contacts at the ends. The specific design of the VMJ cell can, in essence, provide the output characteristics of high voltage and low series resistance, making it ideal for high performance in high-intensity photoelectric concentrators. Another key feature of the VMJ element is the simplicity of its design, which leads to low production costs.

The effectiveness of the VMJ can be confirmed on the basis of the performance data taken from the experimental VMJ element with 40 consecutive transitions in the range from 100 to 2500 solar radiation intensities, in which the output power density exceeds 400,000 watts / m ² at 25 volts with an efficiency close to 20% . It should be appreciated that the aforementioned performance in VMJ solar cells was obtained at a low production cost and low degree of production complexity. It is believed that these aspects are necessary ways to achieve real technical productivity and economic efficiency, necessary in order to make photovoltaic concentrator systems more cost-effective and viable in solving global energy problems. In addition, any increase in cell performance (for example, more watts at the output) should directly lead to a reduction in the size of the hub system (for example, lower costs associated with the list of materials used), which will lead to a lower cost of $ / watts of photovoltaic energy.

It should be noted that a lower cost of $ / watt is very essential for the adoption and introduction of solar cell technology on the market, as world energy requirements are constantly increasing not only in developing, but also in developed countries, while prices for traditional minerals fuel is growing. There is also widespread widespread concern over all related issues, such as environmental pollution, global warming, and national security, and the economic dangers associated with dependence on foreign fuel suppliers. These environmental, economic, and safety factors, coupled with growing public attention, have increased interest in finding more cost-effective and environmentally friendly renewable energy solutions. Of all the available renewable energy sources, solar energy has the greatest potential in meeting the need for efficiency and environmental safety. In fact, the Earth receives more energy in the form of sunlight every few minutes than humanity can consume from all resources in a whole year.

Although photovoltaic is widely known as an ideal renewable energy technology, the associated costs can be a major barrier to adoption and market adoption. Prior to gaining market share and adoption, photovoltaic-based energy should become competitive in terms of price with conventional energy sources, including coal-based energy, whose production technology is well developed and accepted among consumers and has good cost-effectiveness. Moreover, access to cheap electric energy is considered a determining factor in the global economy; therefore, terawatts (for example, thousands of gigawatts) of power from photovoltaic systems may be required. Market research shows that installed systems based on photovoltaic energy should lower the estimated price to $ 3 / watt or less before they become competitive without subsidies in a wide area of application. Since the cost for installed photovoltaic systems currently exceeds $ 6 / watt, a significant improvement in terms of cost is still needed.

Trying to get a lower $ / watt characteristic has been the primary goal of more research and improvement in photovoltaic technology over the past few decades. Despite the fact that industry spends billions of dollars developing various technologies in order to obtain more cost-effective photovoltaic energy, the existing photovoltaic industry still requires significant subsidies to support sales, which can be an indicator of the adverse conditions for market development and industrial development.

Silicon solar cells, which remain almost the same as during their initial discovery and development in the 1960s, currently dominate, accounting for ~ 93% of the photovoltaic market. The existing photovoltaic industry, in an attempt to reduce cost, relied heavily on the suitability of low-cost low-quality silicon semiconductor for the production of traditional solar cells. It should be noted that such low-quality silicon, often called solar-grade silicon, is mainly the head and back parts of the ingots left after the wafer production, and the material that does not meet the technical requirements rejected by the manufacturers of semiconductor devices that need higher-quality silicon wafers of the highest quality . Although photovoltaic sales have grown rapidly, growing ~ 40% annually over the past decade, with production estimated at 3.8 gigawatts (GW) in 2007, sales are now hampered by shortages and higher prices for solar-grade silicon. Although superior quality silicon is available, it is not considered an option, as it will increase the level of production cost.

For conventional conventional solar cells, more than half the cost of production is the raw semiconductor polysilicon used to produce wafers for solar cells. As a result, a conventional solar cell with an efficiency of 14% is designed for 0.014 W / cm ² and has a silicon wafer cost of more than $ 3 / watt (or $ 0.042 / cm ² ) before any additional manufacturing process. Consequently, the existing photovoltaic industry is forced to pay attention and make a decision regarding the fact that only the initial cost of silicon material already exceeds the estimated price that enterprises need to sell on a larger scale. For comparison, semiconductor manufacturers manufacturing microprocessor chips, which are sold at a price of more than $ 100 / cm ² , based on an area estimate, can afford the costs associated with using superior quality silicon wafers.

The shortage of solar-grade silicon and the inability of the photovoltaic industry to reach an important estimated price, coupled with the advent of new, more efficient three-junction solar cells, has recently sparked significant renewed interest in photovoltaic concentrators. The obvious advantage of photovoltaic concentrators is the potential price advantage resulting from the use of large areas of inexpensive materials (glass reflectors or plastic lenses) to concentrate sunlight on much smaller areas of expensive solar cells, thus using cheap materials as a replacement for expensive materials. Development of the design of photovoltaic concentrators for 1000 times the intensity of solar radiation will significantly reduce the need for expensive semiconductor silicon by ~ 99.9%, that VMJ 1000 MW cells can use the same amount of expensive semiconductor silicon that is currently needed for traditional solar cells on 1 MW. In fact, this is considered a practical approach to mitigate any problems associated with a lack of silicon.

The main work on solar concentrators was mainly focused on improving the designs of solar cells of silicon concentrators for high intensity; a lot of significant work was done during the energy crisis of the 1970s, which at that time showed modest unsatisfactory results regarding costs. Research and improvement has been carried out, initially targeting solar cells for concentrator systems to operate at 500 solar intensities; Nevertheless, the goal was reduced to 250 solar radiation intensities when faced with insoluble improvement problems associated with an attempt to solve the problem of series connection in the design of the solar cell under study. For example, the high series losses in the solar cells of the concentrator became an obvious main problem that the technology of the traditional VMJ solar cell took into account and solved. It should be noted that a significant part of the solar cells developed for the technology of the concentrator is rather complicated and expensive in terms of production, with 6 or 7 high-temperature stages (> 1000 ° C) and 6 or 7 stages of photolithographic masking. This complexity refers to attempts at the design level to minimize losses of series connection, which initially limited operation at maximum intensity, in the best of these structures, equal to no more than 250 solar radiation intensities. Such complexity and associated costs hindered the significant development of hub technology and related solar cell technology and contributed to the development of alternative technologies such as thin-film solar cell technology.

The technology of multi-junction (VMJ) solar cells with vertical transitions is significantly different from traditional solar cells of the concentrator. VMJ technology of solar cells provides at least two advantages relative to other technologies: (1) it does not require photolithography, and (2) one stage of high-temperature diffusion, at temperatures above 1000 ° C, can be used to form both transitions. Therefore, a lower production cost is set. In addition, VMJ solar cells can operate at high intensities, for example, at 2500 intensities of solar radiation. It is immediately clear from such operating conditions that the resistance of the series connection is not a problem for the design of the VMJ element; even at intensities with an order of magnitude greater than traditionally proposed for reasons of expediency, it was not viable from the point of view of the economy. Also, the current density in a single VMJ cell at 2500 solar radiation intensities is usually about 70 A / cm ² , which is the level of radiation that can cause significant damage to most solar cells based on other technologies.

As indicated above, renewed interest in photovoltaic concentrators is growing due to the development of solar cells with three transitions made using materials of groups III-V, including gallium (Ga), phosphorus (P), arsenide (As), indium (In) and germanium (Ge). An element with three transitions can involve from 20 to 30 different semiconductor layers connected in series over a germanium wafer: doped GaInP ₂ and GaAs layers grown in a reactor for chemical vapor deposition of organometallic compounds (MOCVD), where each semiconductor will have a characteristic forbidden width energy zone, which will lead to the fact that it will absorb sunlight most effectively with a certain color. The semiconductor layers are carefully selected to absorb almost the entire spectrum of solar radiation, thus generating as much electricity from the light as possible. These multi-junction devices are the most efficient solar cells to date, reaching a high of 40.7% efficiency with moderate sunlight concentration and laboratory conditions. But, since they are expensive in terms of production, their use in photovoltaic concentrators is necessary.

Nevertheless, the need for materials and the cost of materials of solar cells of groups III-V are rapidly increasing. For example, over 12 months (12 / 2006-12 / 2007), the cost of pure gallium increased from about $ 350 per kg to $ 680 per kg, and prices for germanium increased significantly to $ 1000- $ 1200 per kg. The price of indium, which was $ 94 per kg in 2002, increased to almost $ 1,000 per kg in 2007. In addition, demand for India is projected to continue to increase due to the large volume of production of thin-walled (CuInGaSe) solar cells launched by several new companies in 2007 year. Moreover, indium is a rare element that is widely used to form a transparent electric coating in the form of indium and tin oxide for liquid crystal displays and large flat panel monitors. In fact, these materials are not viable in terms of long-term photovoltaic (PV) solutions needed to provide terawatts of cheap energy to solve global energy problems.

Despite the fact that semiconductor solar cells of III-V groups with an area of 0.26685 cm ² can generate energy equal to 2.6 watts or about 10 W / cm ² , and it was previously estimated that such a technology can ultimately produce electricity at a price 8-10 cents / kWh, almost equal to the price of electricity from traditional sources, further analysis may be required to confirm this estimate. However, VMJ solar cells have demonstrated an output power exceeding 40 W / cm ² at 2500 solar intensities using the least expensive semiconductor material with a low manufacturing cost. (This output power exceeds 400,000 W / m ^2. ) Along with a complex of PV technologies based on advanced materials, the technology of solar cells based on Si remains generally predominant in photovoltaic cells and applications. Moreover, in the event of a global need, silicon is the only semiconductor material with an existing industrial base that will be able to provide terawatts of photovoltaic energy in the foreseeable future for widespread global use.

SUMMARY OF THE INVENTION

The following description is a simplified summary of the invention in order to provide a basic understanding of some of the aspects described here. The description of the invention is not a detailed description and is not intended to identify key / critical elements or to limit the scope of the various aspects described herein. Its sole purpose is to provide some concepts in a simplified form as an introduction to the more detailed description that is presented behind it.

The present invention provides semiconductor-based photovoltaic cells that reduce the recombination losses of photogenerated carriers. In an aspect, in order to reduce recombination losses, the diffuse doped layers in the active photovoltaic cells are coated with the structure of the dielectric material (s), which reduces the contact between the metal contacts and the active PV element. Various structures can be used, and one or more surfaces of the PV element can be coated with one or more dielectrics. Multi-junction (VMJ) vertical transition solar cells can be produced with structured PV elements or individual cells. Structured PV cells can increase the series resistance of the VMJ solar cells, and structuring one or more surfaces of the PV cells can increase the complexity of the process involved in manufacturing VMJ solar cells; however, a decrease in carrier loss in diffuse alloyed layers can increase the efficiency of solar cells and thus provide PV with operational advantages that outweigh the increase in manufacturing complexity. A system that makes possible the production of PV elements based on semiconductors is also provided.

Aspects or features described here and their associated benefits, such as reducing the recombination losses of photogenerated carriers, can be used in any class of photovoltaic cells, such as solar cells, thermophotovoltaic cells, or cells excited by laser sources or photons. In addition, aspects of the present invention may also be practiced in another class (s) of energy converting elements, such as beta electric elements.

This invention reduces the bulk of the recombination loss in a multi-junction (VMJ) element with vertical transitions by texturing the light receiving surfaces. Textures can be in the form of grooved grooves, such as configurations with a cross section in the shape of a “V”, configurations with a cross section in the shape of a “U” and the like, where a plane that includes configurations with such a cross section is almost perpendicular to the direction of application the individual elements that form the VMJ. In one aspect, a plane that includes substantially periodically repeating cross sections (for example, when considering a cross section in the direction in which grooves pass along it) is substantially perpendicular to the direction of application of the individual elements. This arrangement facilitates the direction of the refracted light from the p + and n- diffuse doped regions of VMJ, while at the same time creating the desired carriers in a decreasing volume. Accordingly, incident light can be refracted on a plane that includes a cross-sectional configuration and which is substantially perpendicular to the direction of application of the individual elements.

It should be appreciated that the texturing for the VMJ of the present invention differs from the prior art for the textures of traditional silicon semiconductor elements, both in the orientation of the PN junctions and / or in the interaction with incident light. For example, traditional silicon photovoltaic cells are typically textured so as to deflect penetrating light so that more waves having a longer wavelength are absorbed closer to the PN junctions (horizontally) for better current collection by carriers, and therefore mitigate low spectral sensitivity to large wavelengths in the spectrum of solar radiation. Conversely, this is not required in the VMJ of the present invention, which includes vertical transitions and, therefore, already provides increased spectral sensitivity to longer waves in the spectrum of solar radiation.

In a separate aspect, the result of the use of grooves in accordance with this invention (for example, grooves in the form of V) is to reduce the main part of the recombination losses by reducing the volume of the main part (compared to surfaces of traditional solar cells with a texture that reduces reflection or approximates reflected or refracted light to the transitions). In particular, VMJ elements have demonstrated better carrier current collection for both short wavelengths and long wavelengths, where sensitivity to short wavelengths is observed due to the exclusion of heavily doped horizontal transitions on the upper surface, and sensitivity to long wavelengths is observed due to the increased the efficiency of collecting vertical transitions. As another example, if instead of a grooved grooved texture in accordance with this invention, other textures (for example, with a random, pyramidal, domed or similar protruding configuration) would be used as part of the VMJ, the incident light would begin to refract in all directions , which would lead to the absorption of light in p + and n + diffuse regions and, consequently, to reduced efficiency.

According to a related method, at the initial stage, the VMJ can be formed by overlaying (as a packet) a plurality of individual elements, where each element itself can include a plurality of parallel semiconductor substrates or layers that are folded together. Each layer may consist of an unclean doped semiconductor material that forms a PN junction, and also include a “built-in” electrostatic drift field that facilitates the movement of minority carriers toward such a PN junction. Then many of these individual elements are combined to form a VMJ. Further, grooves in the form of recesses can be formed on the surface VMJ of the element that receives the light (for example, by means of a semiconductor wafer cutting machine), where a plane that includes a cross section of the configuration is substantially perpendicular to the direction of application of the individual elements that form the VMJ. Accordingly, incident light can be refracted in a plane that includes repeating configurations with a cross section and which is almost perpendicular to the direction of application of the individual elements (for example, thus providing stronger absorption for a given depth). Moreover, the various rear (s) surface (s) and side (s) with a reflective coating can be used in combination with various aspects of the present invention.

In a related aspect, the grooved surface of the present invention also improves carrier removal, while reducing most of the recombination loss. For example, V-shaped grooves can be arranged perpendicular to p + nn + (or n + pp +) individual elements in order to increase the optical length of the absorption paths of longer wavelengths in the solar spectrum and make light absorption almost entirely limited inside the main volume of the n-type region p + nn + individual elements. Moreover, such V-shaped grooves may have an antireflection coating used to improve the absorption of incident light by the element.

In a related aspect, the invention reduces the bulk of the recombination losses in a multi-junction (VMJ) element with vertical transitions by structuring its light-receiving surface. The textures can take the form of recessed grooves, such as configurations with a cross section in the shape of “V”, configurations with a cross section in the shape of “U” and the like, where a plane that includes such a configuration with a cross section is almost perpendicular to the direction of application of the individual elements that form VMJ. In one aspect, a plane that includes constantly repeating cross sections (for example, creating a cross section in the direction in which the grooves extend) is substantially perpendicular to the direction of application of the individual elements. This arrangement facilitates the direction of the refracted light from the p + and n- diffuse doped regions of VMJ, while at the same time creating the desired carriers in a decreasing volume. Accordingly, incident light can be refracted on a plane that includes a cross-sectional configuration and which is substantially perpendicular to the direction of application of the individual elements.

It should be appreciated that the texturing for the VMJ of the present invention differs from the prior art for the textures of traditional silicon semiconductor elements, both in the orientation of the PN junctions and / or in the interaction with incident light. For example, traditional silicon photovoltaic cells are typically textured so as to deflect penetrating light so that more waves having a longer wavelength are absorbed closer to the PN junctions (horizontally) for better current collection by carriers, and therefore mitigate low spectral sensitivity to large wavelengths in the spectrum of solar radiation. Conversely, this is not required in the VMJ of the present invention, which includes vertical transitions and, therefore, already provides increased spectral sensitivity to longer waves in the spectrum of solar radiation.

In a separate aspect, the result of the use of grooves in accordance with this invention (for example, grooves in the form of V) is to reduce the main part of the recombination losses by reducing the volume of the main part (compared with the surfaces of traditional solar cells with a structure that reduces reflection or approximates reflected or refracted light to the transitions). In particular, VMJ elements have demonstrated better carrier current collection for both short wavelengths and long wavelengths, where sensitivity to short wavelengths is observed due to the exclusion of heavily doped horizontal transitions on the upper surface, and sensitivity to long wavelengths is observed due to the increased the efficiency of collecting vertical transitions. As another example, if instead of the structure of the grooves of the deepened shape in accordance with this invention, other structures (for example, with a random, pyramidal, domed or similar protruding configuration) would be used as part of the VMJ, the incident light will begin to refract in all directions, which will lead to light absorption in p + and n + diffuse regions and, therefore, to reduced efficiency.

According to a related method, at the initial stage, the VMJ can be formed by superimposing a plurality of individual elements, where each element itself can include a plurality of parallel semiconductor substrates or layers that are folded together. Each layer can consist of an unclean doped semiconductor material that forms a PN junction, and also include a “built-in” electrostatic drift field, which increases the low carrier velocity towards such a PN junction. Then many of these individual elements are combined to form a VMJ. Further, grooves in the form of recesses can be formed on the surface VMJ of the element that receives the light (for example, by means of a semiconductor wafer cutting machine), where a plane that includes a cross section of the configuration is substantially perpendicular to the direction of application of the individual elements that form the VMJ. Accordingly, incident light can be refracted in a plane that includes repeating configurations with a cross section and which is almost perpendicular to the direction of application of the individual elements (for example, thus providing stronger absorption for a given depth). Moreover, the various rear (s) surface (s) and side (s) with a reflective coating can be used in combination with various aspects of the present invention.

In a related aspect, the grooved surface of the present invention also improves carrier removal, while reducing most of the recombination loss. For example, V-shaped grooves can be arranged perpendicular to p + nn + (or n + pp +) individual elements in order to increase the optical length of the absorption paths of longer wavelengths in the solar spectrum and make light absorption almost entirely limited inside the main volume of the n-type region p + nn + individual elements. Moreover, such V-shaped grooves may have an antireflection coating used to improve the absorption of incident light by the element.

In another aspect, the invention provides buffer zone (s) at the end of the layers of a silicon multi-junction (VMJ) photovoltaic cell with high voltage vertical junctions to provide a barrier that protects the active layers while providing ohmic contact. Such buffer zone (s) may be in the form of a structure of inactive layer (s), which is additionally superimposed on and / or under the end layers of the VMJ element. The VMJ element itself can include many separate elements, where each individual element uses several active layers (for example, three) to form a PN junction and an “built-in” electrostatic drift field (which increases the low velocity of the carrier toward the PN junction).

Accordingly, various active layers, such as nn + and / or p + n junctions located at both ends of the VMJ element (and which are parts of its individual elements), can be protected from adverse types of pressure and / or tension (for example, from thermal / mechanical compression, twisting, stress, deformation and the like, which can be applied to VMJ in the process of its production and / or operation). Moreover, the buffer zone can be formed using materials that have an ohmic contact of very low resistance, both metals and semiconductors, such that it does not lead to any significant losses in series resistance in the photovoltaic cell under operating conditions. For example, a buffer zone can be formed by using low-resistance p-type doped silicon wafers in such a way that when using other p-type dopants, such as aluminum alloys in the production of a VMJ photovoltaic cell, it will reduce the risk of self-alloying (compared to using n-type plates, which can create unwanted pn junctions), when the goal is to create an ohmic contact of very low resistance. It should be appreciated that this invention can be used as part of any class of photovoltaic cells, such as solar cells and thermophotovoltaic cells. In addition, aspects of the present invention can also be applied to energy converting elements of another class (s), such as beta-electric elements.

In related aspects, the buffer zone may be in the form of a bandage on the surface of the end layer of an individual element, which acts as a protective border for such an active layer and also frames the VMJ element for ease of handling and transportation. Also, by providing a protective grip of the VMJ element, the design of such a band also facilitates the anti-reflection coating procedure (for example, the coating can be applied evenly when the element is held securely during processing, for example, by means of a mechanical clamp). Moreover, buffer zones (for example, inactive layers located at the ends of VMJ) can be physically located next to other buffer zones during deposition, and therefore, any unwanted dielectric coating material that adversely penetrates lower onto contact surfaces can be easily deleted without damaging active individual items. The buffer zone can be formed from highly doped silicon of very low resistance (for example, a thickness of the order of 0.008 ”). Such a buffer zone may generally be in contact with conductors that enclose or separate the VMJ element from another VMJ element in the structure of the photoelectric element.

In accordance with a further aspect, a buffer zone may be located between the electrical contact and the active layers of the VMJ cells. Moreover, such buffer zones may have thermal expansion characteristics that substantially coincide with the characteristics of the active layers, thereby reducing performance degradation (for example, the reduction in pressure / tension applied when conductors are welded or brazed during production). For example, heavily doped silicon layers of low resistance can be used, which coincide in value of the coefficient of thermal expansion (3 × 10 ^-6 / ° C) with all active individual elements. Accordingly, a very good ohmic contact can be provided by the active individual elements, which further reduces the problems associated with pressure caused by welding / solder and / or mismatch of the thermal expansion coefficients of the contact materials. Other examples include metal layers, such as tungsten (4.5 × 10 ^-6 / ° C) or molybdenum (5.3 × 10 ^-6 / ° C), which are selected for their thermal expansion coefficients that are almost equal to the coefficient of active silicon (3 × 10 ^-6 / ° C) p + nn + of individual elements. Metallization applied to the outer layers of silicon layers of low resistance of the buffer zone or to the metal layers of the electrodes, which are fused with the active individual elements, can be carried out by welding or solder without exerting dangerous pressure on a solar cell of high intensity or a photovoltaic cell, where such outer layers serve as ohmic contacts, rather than parts of individual elements connected in series with other individual elements.

Various aspects of the present invention can be applied as part of a wafer having (111) Miller indices for orienting the bound crystal planes of the buffer zone, which is considered more mechanically strong and more resistant to etching compared to (100) silicon with a crystalline orientation commonly used for manufacturing active VMJ single elements. Accordingly, silicon layers of low resistance can have a crystalline orientation different from the orientation of the active individual elements, where by applying such an alternative orientation, a device with improved mechanical strength / end contacts is provided. In other words, the edges of (100) oriented individual elements are usually etched faster and substantially rounded off the corners of the active individual elements with such a crystalline orientation as compared with inactive (111) oriented end layers, thus obtaining a more reliable structure of the device with greater mechanical strength for welding or another way to attach the terminal contacts.

In a related aspect, the present invention uses a multi-junction (VMJ) vertical junction photoelectric cell to provide electrolysis to compounds (e.g., water) through incident light and current generation for electrolysis (e.g., hydrogen and oxygen generation). Such a VMJ includes many individual cells in contact with the electrolyte, where each individual cell uses several active layers (for example, three) to form a PN junction and an “built-in” electrostatic drift field (which increases the low velocity toward the PN junction). A VMJ can be partially or completely immersed in water / electrolytes as part of a transparent casing made of a material such as glass or plastic, where when light is applied to such a VMJ, a plurality of electrolysis electrodes (anodes / cathodes) can be formed through the VMJ. The current passing between such electrodes for electrolysis flows through the water and decomposes the water into hydrogen and oxygen when the threshold value of the electrolysis voltage is reached. Typically, this threshold value for the decomposition voltage is in the range of 1.18 volts to 1.6 volts in order to break down water and create hydrogen and oxygen. It should be appreciated that large voltage values can be achieved by superimposing a plurality of individual elements (eg, a plurality of elements connected in series). In addition, the addition of catalysts can also be used to increase the efficiency of hydrogen and oxygen evolution and reduce semiconductor corrosion caused by the high electrode potential and electrolyte solutions. Moreover, the electrolyte can be formed from any solutions that do not adversely affect the superimposed layers that form the VMJ element (for example, iridium-based material made from iridium, its binary alloy or its oxide).

In a related aspect, the VMJ is partially or completely immersed in water / electrolyte and may include protruding metal regions (e.g., VMJ electrodes) that protrude above the silicon of the VMJ cell to increase the contact area with water and electrolyte and accelerate the production of hydrogen. Such protrusions may be of the order of several millimeters, for example. In accordance with another aspect, very thin layers of electrocatalyst materials, such as platinum, RuO ₂ or titanium, can be incorporated into the metal coating during the manufacturing of the VMJ cell to accelerate the formation of hydrogen. Moreover, there is a good opportunity to choose a material that is an electrocatalyst, since the n + negative (-) side of the metal coating may differ from the metal coating p + of the positive (+) side. It should be appreciated that one skilled in the art can easily select catalyst materials that will accelerate hydrogen production and are stable and compatible with the production of a VMJ cell. Moreover, ultrasonic devices can be used to release the resulting oxygen and hydrogen bubbles that remain attached to the electrodes for electrolysis. It should be appreciated that the electrolyte flow can also remove such formed bubbles.

According to a related method, an electrolyte solution is introduced into a container that includes a VMJ in which it is completely or almost completely immersed. Such a system is then placed under the incident light, and an electric current is generated in the VMJ. The incident light on the VMJ can generate electric current through an electrolyte solution, and in any place where the threshold value for water decomposition is reached or exceeded (for example, about 1.6 volts), water is electrolyzed. For example, a voltage of 0.6 volts can be generated on each individual cell (for example, for 1000 solar radiation intensities), and electrolysis can occur between the regions of the first individual cell and the third individual cell. Accordingly, various collection mechanisms (e.g., membranes, grating plates, and the like) for collecting the obtained gaseous oxygen and hydrogen can be placed between regions where the voltage exceeds the threshold value for water electrolysis (e.g., about 1.6 volts), and decomposition is assumed water. It should be appreciated that such collection mechanisms may also be located downstream of the electrolyte stream to collect the obtained gaseous oxygen and hydrogen.

To complete the following and related outcomes, certain illustrative aspects are described herein in connection with the following description and the attached drawings. These aspects point to various uses, all of which are believed to be described herein. Other advantages and new features may become apparent from the following detailed description when considered in conjunction with the drawings.

Brief Description of the Drawings

FIG. 1 is a schematic perspective view of a textured or grooved surface as part of a vertical transition multi-junction (VMJ) element in accordance with an aspect of the present invention.

Figure 2 depicts an exemplary cross-section of grooves used according to this invention.

Figure 3 depicts, by way of example, an overlay of individual elements to form a VMJ with a grooved surface in accordance with an aspect of the present invention.

Figure 4 depicts a particular individual element, which in part forms a VMJ in accordance with an aspect of the present invention.

Figure 5 depicts a related method for creating a VMJ with a grooved surface to reduce most of the recombination loss in accordance with an aspect of the present invention.

6 depicts a schematic structural diagram of the structure of buffer zones as part of a multi-junction (VMJ) element with vertical transitions in accordance with an aspect of the present invention.

7 depicts a separate aspect of a single element, the structure of which can form a VMJ element in accordance with an aspect of the present invention.

Fig. 8 shows, by way of example, a cross section of a buffer zone in the form of a formed band on the surfaces of individual elements located at both ends of the VMJ.

Fig.9 depicts a related method of applying buffer zones on the end layers of a silicon multi-junction (VMJ) high voltage photovoltaic cell to provide a barrier that protects its active layers.

10 is a schematic cross-sectional view of a solar installation that includes a modular structure of photovoltaic (PV) cells in which VMJs with buffer zones can be used.

11 depicts a schematic structural diagram of a system for electrolysis, which uses a multi-junction (VMJ) cell with vertical transitions for electrolysis of water in accordance with an aspect of the present invention.

12 depicts protrusions of metal layers above the surface of the VMJ, which can facilitate the electrolysis process.

13 shows a voltage gradient along VMJ and through superimposed elements as parts thereof.

Fig. 14 depicts a method of electrolyzing water by VMJ in accordance with an aspect of the present invention.

15 depicts a VMJ cell that can be used for electrolysis according to this invention.

Fig. 16 depicts one single cell, a plurality of which forms a VMJ for electrolysis of the present invention.

17 depicts a VMJ cell with grooved surfaces to improve the efficiency of the electrolysis process.

FIG. 18 shows, by way of example, grooves for the surface of a VMJ used for electrolysis in accordance with an aspect of the present invention.

19A and 19B are diagrams of an exemplary configuration of structured surfaces of PV elements in accordance with aspects disclosed herein. FIG. 19C is a diagram of an exemplary set of starting materials and obtained PV elements that can be produced by alloying in accordance with the aspects described herein.

20A-20C are diagrams of exemplary configurations of a structured dielectric coating of PV elements and an explanatory unit VMJ in accordance with aspects described herein. Fig.20D depicts a VMJ PV element processed to obtain an open special crystalline surface.

21A-21C are diagrams of exemplary configurations of a structured dielectric coating of PV elements and a VMJ explanatory block in accordance with aspects described herein.

FIG. 22 is a cross-sectional diagram of an example configuration of a structured dielectric coating of an active PV element with a reduced diffuse alloy layer in accordance with aspects described herein.

23A and 23B are diagrams of exemplary configurations of structured dielectric coatings of a PV cell in accordance with aspects described herein.

24 is a perspective view of an embodiment of a textured surface photoelectric cell in accordance with aspects described herein.

25 is a flowchart of an example method for manufacturing a photovoltaic cell with reduced recombination loss of carriers in accordance with aspects disclosed herein.

FIG. 26 is a flowchart of an exemplary method for manufacturing VMJ solar cells with reduced recombination loss of carriers in accordance with aspects described herein.

FIG. 27 is a block diagram of an example system that enables the production of solar cells in accordance with the aspects described herein.

Detailed description

The present invention will now be described with reference to the drawings, where the same reference numbers are used to refer to the same elements. In the following description, for purposes of explanation, numerous individual details are described in order to provide a thorough understanding of the present invention. It may be obvious, however, that the invention can be used without these individual details. In other instances, well-known structures and devices are shown in block diagrams in order to facilitate describing the present invention.

In this specification, the appended claims, or the drawings, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. This means, unless otherwise specified separately, or clear from the context, that the phrase “X uses A or B” is intended to mean any inclusive permutations. That is, if X uses A, X uses B, or X uses both A and B, then “X uses A or B” is satisfied in any of the following cases. Moreover, the articles "a", "an", as used in this description and the attached drawings, should, in general, be construed to mean "one or more", unless separately established or clear from the context, that they are singular.

Moreover, regarding the terminology of impurity-doped materials that are part of the photovoltaic cells described here for doping with a donor impurity, the terms “n-type” and “N-type” are used interchangeably, as are the terms “n + -type” and “N + -type. " For alloying with acceptor impurities, the terms “p-type” and “P-type” are also used interchangeably, as well as the terms “p + type” and “P + type”. For clarity, the type of doping is also indicated by the abbreviation, for example, the n-type is designated as N, the p + type is designated as P +, etc. Multilayer photovoltaic cells or individual cells are indicated by a set of letters, each of which indicates the type of layer doping; for example, a p-type / n-type transition is denoted by PN, while a p + -type / n-type transition of / n + -type is denoted by P + NN +; the designation of other transition combinations also corresponds to this notation.

FIG. 1 is a schematic perspective view of a grooved surface 100 as part of a multi-junction (VMJ) vertical transition element 120 in accordance with an aspect of the present invention. Such a texture for texturing 100 allows the refracted light to be directed from the p + and n + diffuse doped regions, while at the same time the desired carriers are created. Accordingly, incident light can be refracted in a plane 110 having a normal vector n. Such a plane 110 is parallel to the PN junction planes of VMJ 10 and may include a cross-sectional configuration of grooves 100. Moreover, an antireflection coating can be applied to the textured surface 100 to increase the absorption of incident light in the element. In other words, the orientation of the plane 110 is almost perpendicular to the direction of overlapping of the individual elements 111, 113, 115. It should be appreciated that other orientations other than the perpendicular can also be considered (for example, crystalline planes open at different angles), and all such aspects need to be considered within the scope of this invention.

Figure 2 depicts example textures for grooves on a surface of a VMJ that receives light. Such grooves can be in the form of grooves of a deepened shape, for example, such as a configuration with a cross section in the shape of a “V” having different angles (for example, 0 ° <θ <180 °), a configuration with a cross section in the shape of a “U” and similar, where a plane that includes a cross-sectional configuration is substantially perpendicular to the direction of application of the individual elements that form the VMJ and / or substantially parallel to the PN junctions of the VMJ. It should be appreciated that the texturing 210, 220, 230 for the VMJ of the present invention is different from the textures of conventional silicon photovoltaic cells known in the art in the orientation of PN junctions and / or interaction with incident light. For example, traditional silicon photovoltaic cells are typically textured so as to deflect penetrating light so that more waves having a longer wavelength are absorbed closer to the PN junctions (horizontally) for better current collection by carriers, and therefore mitigate low spectral sensitivity to large wavelengths in the spectrum of solar radiation. Conversely, this is not required in the VMJ of the present invention, which includes vertical transitions and, therefore, already provides increased spectral sensitivity to longer waves in the spectrum of solar radiation.

Preferably, one aspect of the use of grooves in accordance with this invention (for example, grooves in the form of V) is to reduce the main part of the recombination losses by reducing the volume of the main part (compared to surfaces of traditional solar cells with a texture that reduces reflection or approximates reflected or refracted light to the transitions). In particular, the VMJ element demonstrated the best carrier current collection for both short wavelengths and long wavelengths, where sensitivity to short wavelengths is observed due to the exclusion of heavily doped horizontal transitions on the upper surface, and sensitivity to long wavelengths is observed due to the increased the efficiency of collecting vertical transitions. As another example, if instead of the texture of the grooves in the form of recesses in accordance with this invention, other textures (for example, with a random, pyramidal, domed or similar protruding configuration) would be used as part of the VMJ, the incident light would begin to refract in all directions, which would lead to light absorption in the p + and n + diffuse regions and, consequently, to reduced efficiency. It should be appreciated that such grooves in the form of “U” and “V” are given essentially as an example, and other configurations are possible within the scope of the present invention.

Figure 3 depicts the structure of the individual elements 311, 313, 317, which can use the texture with grooves on the side 345 in accordance with an aspect of the present invention. As explained previously, the VMJ 315 itself is formed from a plurality of individual elements 311, 313, 317 connected together (from 1 to k, where k is an integer), where each individual element is itself formed from superimposed substrates or layers (not shown). For example, each individual element 311 may include a plurality of parallel semiconductor substrates stacked together and composed of impurity-doped semiconductor materials that form a PN junction and an “built-in” electrostatic drift field that increases the low velocity of the carrier to such a PN junction. It should be appreciated that various doped layers of N + -type and P-type can be used to form parts of individual elements, and such structures are included in the scope of this invention.

Accordingly, the textures on the surface receiving the light 345 contribute to the refraction of the light to direct it from the p + and n + diffuse doped regions, while at the same time the desired carriers are created. Thus, incident light can be refracted in a plane that includes a configuration with a cross section and which is almost perpendicular to the direction of application of the individual elements (for example, perpendicular to the vector n).

Figure 4 depicts a separate aspect of a single element, the structure of which can form a VMJ element having textured grooves according to this invention. The individual element 400 includes layers 411, 413, 415, folded together in a substantially parallel structure. Such layers 411, 413, 415 may also include impurity-doped semiconductor material, where layer 413 is of the same type of conductivity and layer 411 is of the opposite type of conductivity to establish a PN junction at junction 412. Also, layer 415 can be of the same type of conductivity as layer 413, but with a significantly higher concentration of impurities, thus generating an integrated electrostatic drift field, which increases the low carrier velocity towards the PN junction 412. Such individual elements can be joined together to form a VMJ and a grooved surface in accordance with various aspects of the present invention.

In accordance with another aspect, in order to produce a VMJ from a plurality of elements 400, identical PNN + (or NPP +) junctions can first be formed at a depth of about 3 to 10 microns in high-resistance silicon flat wafers (e.g., greater than 100 ohms per cm) N type (or P type) having a thickness of approximately 0.008 inches. Further, such PNN + plates are folded together with a thin layer of aluminum located between them, where the PNN + transition and the crystalline orientation of each plate can be directed in the same direction. Moreover, aluminum-silicon fusible alloys can be used or metals, such as molybdenum or tungsten, which have thermal coefficient (s), which practically coincide with the thermal coefficient of silicon. Further, silicon wafers and aluminum surfaces can be fused together so that the superimposed structure can be connected. Buffer zones with very low resistance can also be used as the structure of the inactive layer (s), which is additionally superimposed on and / or under the end layers of the VMJ element, thereby using a barrier that protects the active layers from adverse types of pressure and / or stretching (for example, from thermal / mechanical compression, twisting, stress, deformation, and the like, which may be applied to the VMJ during its production and / or operation). The surface of such an element can then be covered with grooves to reduce the bulk of the recombination loss, as described in detail above. It should be appreciated that other material, such as germanium or titanium, can also be used. Also, aluminum-silicon fusible alloys can also be used.

5 depicts a related method 500 of applying grooves to a surface VMJ that receives light. While the exemplary method is depicted and described herein as a sequence of blocks representing various events and / or actions, the present invention is not limited to the illustrated order of such blocks. For example, some actions or events may occur in different sequences and / or simultaneously with other actions or events, in contrast to the sequence depicted here, in accordance with the invention. In addition, not all illustrated blocks, events, or actions may be required to apply the method in accordance with this invention. Moreover, it will be appreciated that the exemplary method and other methods in accordance with the invention can be applied in connection with the method depicted and described here, as well as in connection with other systems and installations not shown or not described.

First, at step 510, a plurality of individual PN junction elements are formed, as described in detail above. As previously explained, each individual element itself may include a plurality of parallel semiconductor substrates that are connected together. Each layer can consist of impurity-doped semiconductor material, which forms a PN junction, and also includes a “built-in” electrostatic drift field, which increases the low velocity of carriers to such a PN junction. Next, at step 520, many of these individual elements are combined to form a VMJ, where buffer zones can also be used to protect such elements (for example, from pressure / tension applied to them during the manufacturing process). Next, at step 530, recessed grooves can be formed on the VMJ surface that receives the light (for example, using a semiconductor wafer cutting machine), where a plane that includes a cross-sectional configuration is substantially perpendicular to the direction of application of the individual elements that form the VMJ . Next, at step 540, the light can be refracted in a plane that includes a cross-sectional configuration (and / or parallel to the PN junctions) and which is practically perpendicular to the direction of application of the individual elements.

6 depicts a schematic structural diagram of a structure for buffer zones that are part of a multi-junction (VMJ) element with vertical transitions in accordance with an aspect of the present invention. VMJ 615 itself is formed from a plurality of connected individual elements 611, 617 (1 through n, n is an integer), where each individual element itself is formed from stacked substrates or layers (not shown). For example, each individual element 611, 617 may include a plurality of parallel semiconductor substrates connected together and consisting of impurity-doped semiconductor material that forms a PN junction and an “built-in” electrostatic drift field that increases the low carrier velocity toward this PN junction. Accordingly, various active layers, such as nn + and / or p + n junctions or pp + and / or pn + junctions located at both ends of the VMJ element 615 (and which are part of the element itself), can be protected from adverse types of pressure and / or tension (for example, from thermal / mechanical compression, twisting, stress, deformation, and the like, which can be applied to the VMJ during its production and / or operation).

Moreover, each of the buffer zones 610, 612 can be formed using a material that has an ohmic contact of very low resistance (for example, in any interval with an upper boundary of less than about 0.5 Ohms per cm), while reducing and / or excluding unwanted auto-doping. For example, buffer zones 610, 612 can be formed by using p-type doped low impedance plates with other p-type impurities, such as aluminum alloys, to reduce the possibility of self-alloying (compared to using n-type plates, which can create unwanted pn junctions when it is desirable to create ohmic contacts of very low resistance).

7 depicts a separate aspect of a single element, the structure of which can form a VMJ element. The individual element 700 includes layers 711, 713, 715, folded together in a substantially parallel structure. Such layers 711, 713, 715 may also include impurity-doped semiconductor material, where layer 713 is a layer of one type of electrical conductivity and layer 711 is a layer of the opposite type of electrical conductivity to determine the PN junction at junction 712. Also, layer 715 may be a layer of the same such as electrical conductivity as layer 713, but with a significantly higher concentration of impurities, thus generating an “embedded” electrostatic drift field that increases the low velocity of carriers in the PN direction Navigate 712. These separate elements may be joined together to form a VMJ, wherein a buffer zone according to the invention may be placed to protect the VMJ and associated individual elements and / or layers that form them.

In accordance with another aspect, in order to produce a VMJ from a plurality of elements 700, identical PNN + (or NPP +) junctions can first be formed at a depth of about 3 to 10 μm in high-resistance silicon flat wafers (e.g., greater than 100 ohms per cm) N type (or P type) having a thickness of about 0.008 inches. Further, such PNN + plates are folded together with a thin layer of aluminum located between them, where the PNN + transition and the crystalline orientation of each plate can be directed in the same direction. Moreover, aluminum-silicon fusible alloys can be used, or metals, such as molybdenum or tungsten, which have thermal coefficient (s), which practically coincide with the thermal coefficient of silicon. Further, the surfaces of the silicon wafers and aluminum surfaces can be fused together so that the superimposed structure can be connected. Moreover, aluminum-silicon fusible alloys can also be used. It should be appreciated that various doped layers of N + -type and P-type can be used as parts of individual elements, and such structures are included in the scope of this invention.

Buffer zones with very low resistance can also be used as the structure of the inactive layer (s), which is additionally superimposed on and / or under the end layers of the VMJ element, thus using a barrier that protects the active layers from adverse types of pressure and / or tension (for example, from thermal / mechanical compression, twisting, stress, deformation, and the like, which may be applied to the VMJ during its production and / or operation).

Fig. 8 shows an exemplary cross-section of a buffer zone in the form of a bandage 810 (812) formed on the surfaces of the end layer 831 (841) of the individual elements 830 (840), which as part forms the VMJ element 800. Such formed bandages 810, 812 protrude into the role of the protective compound for the active layers of the individual elements and also partially frame the VMJ element 800 for ease of handling and transportation (for example, a buffer zone of low resistance and the edge or end contact of the VMJ element). Also, by providing a protective grip of the VMJ element, the design of such a band also facilitates the anti-reflection coating procedure (for example, the coating can be applied evenly when the element is held securely during processing, for example, by means of a mechanical clamp). Moreover, such formed bandages can be physically located next to other formed bandages during the deposition process, where any unwanted dielectric coating material that adversely penetrates below the contact surfaces can be easily removed without damaging individual elements 830, 840. The formed band 810 (812), which is a buffer zone, can be formed from highly doped silicon of very low resistance (for example, a thickness of the order of 0.008 ”), where the formed bandages could t, in general, in contact with the conductors, which fence off or separated VMJ cell from another VMJ cell in a photovoltaic cell structure. Moreover, due to the very low resistance of the buffer zone, conductors are not required in order to have full electrical contact with the buffer zone. Therefore, they can be partial contacts, such as point contacts, or a series connection of point contacts, while still providing good electrical contact. It should be appreciated that FIG. 8 is essentially exemplary, and other options, such as a buffer zone 810 formed during production, relating to surfaces 800, where 810 are connected to active layers 841, are also possible within the scope of this invention. For example, mold 810 may be a partial lead contact with a metal layer in a buffer zone, as previously discussed.

The conductors may be in the form of electrode layers, which are formed by depositing the first conductive material on a substrate, and may include: tungsten, silver, copper, titanium, chromium, cobalt, tantalum, germanium, gold, aluminum, magnesium, manganese, indium, iron, nickel, platinum, zinc, their alloys, indium and tin oxide, other conductive and semiconductor metal oxides, nitrides and silicides, polysilicon, doped amorphous silicon and various metal-containing alloys. In addition, other doped and undoped conductive or semiconductor polymers, oligomers or monomers, such as PEDOT / PSS, polyaniline, polythiophene, polypyrrole, derivatives thereof and the like, can be used for electrodes. Moreover, since some metals may have an oxide layer formed on them, which can adversely affect the performance of the VMJ element, non-metallic materials such as amorphous carbon can also be used to form electrodes. It should be appreciated that the formed bandage of FIG. 8 is exemplary in nature, and other configurations of the buffer zone, such as rectangular, circular cross-sectional areas having surface contact areas with active layers, are within the scope of this invention.

Moreover, another aspect of the present invention can be used as part of films having (111) Miller indices for orientation from the bonded crystal planes of the buffer zones, which are considered mechanically stronger and more slowly etched than (100) crystalline silicon commonly used in produced active individual elements of VMJ. Accordingly, silicon layers of low resistance can have an excellent crystalline orientation from the orientation of the active individual elements, where, by applying such an alternative orientation, a device with improved mechanical strength / end contacts is provided. In other words, the edges of (100) oriented individual elements are usually etched faster to almost rounded corners of the active individual elements with such a crystalline orientation, as compared to inactive (111) oriented end layers, thus leading to a more reliable device structure with greater mechanical strength for welding or any other connection of the end contacts.

Fig.9 depicts a related method of applying buffer zones on the end layers of a silicon multi-junction (VMJ) high voltage photovoltaic cell to provide a barrier that protects its active layers. While the exemplary method is depicted and described herein as a sequence of blocks representing various events and / or actions, the present invention is not limited to the illustrated order of such blocks. For example, some actions or events may occur in different sequences and / or simultaneously with other actions or events, in contrast to the sequence depicted here, in accordance with the invention. In addition, not all illustrated blocks, events, or actions may be required to apply the method in accordance with this invention. Moreover, it will be appreciated that the exemplary method and other methods in accordance with the invention can be applied in connection with the method depicted and described here, as well as in connection with other systems and installations not shown or not described. First, at 910, a plurality of individual PN junction elements are formed, as described in detail above. As explained previously, each individual element itself may include a plurality of parallel semiconductor substrates that are folded together. Each layer can consist of impurity-doped semiconductor material, which forms a PN junction, and also includes a “built-in” electrostatic drift field, which increases the low velocity of carriers to such a PN junction. Next, at 920, a plurality of such individual elements are combined to form a VMJ. Next, at 930, a buffer zone can be used that contacts the end layer of VMJ to provide a barrier that protects its active layers. Such buffer zone (s) (s) may be in the form of a structure of inactive layer (s), which is additionally superimposed on and / or under the end layers of the VMJ element. The VMJ can then be used as the photovoltaic cell in step 940.

FIG. 10 is a schematic cross-sectional view 1000 of a solar installation that includes a modular structure 1020 of photovoltaic (PV) cells 1023, 1025, 1027 (1 to k, where k is an integer). Each PV element may use multiple buffer zone VMJs in accordance with an aspect of the present invention. Typically, each of the PV elements (also called photoelectric cells) 1023, 1025, 1027 can convert light (eg, sunlight) into electrical energy. The modular structure of 1020 PV elements may include standardized elements or segments that simplify the design and provide a flexible structure.

In one exemplary aspect, each of the photovoltaic cells 1023, 1025, 1027 may be a dye sensitized solar cell (DSC) that includes a plurality of glass substrates (not shown) where transparent conductive materials such as a layer of fluorine doped tin oxide are deposited thereon, for example . Such a DSC may also include a semiconductor layer, such as TiO ₂ particles, a dye-sensitizing layer, an electrolyte and catalyst layer, such as Pt (not shown), which may be located between the glass substrates. The semiconductor layer may further be deposited on the coating of a glass substrate, for example. Thus, the electrode and counter electrode can be formed with a redox mediator to control the flow of electrons between them.

Accordingly, the elements 1023, 1025, 1027 experience periodically excitation, oxidation and reduction, which leads to the appearance of a stream of electrons, for example, electrical energy. For example, incident light 1005 excites dye molecules in a dye layer, where light-excited dye molecules further emit electrons into the conducting region of the semiconductor layer. This can cause oxidation of the dye molecules, where the emitted electrons can pass through the semiconductor layer to form an electric current. The electrons then restore the electrolyte in the catalyst bed and return the oxidized dye molecules to a neutral state. Such a cycle of excitation, oxidation and reduction can be continuously repeated to provide electrical energy.

11 is a schematic structural diagram of an electrolysis system that uses a multi-junction (VMJ) cell with vertical junctions 1110 for electrolysis in accordance with an aspect of the present invention. The VMJ 1110 may be partially or completely immersed in water / electrolyte as part of a transparent casing, such as glass, quartz or plastic 1130. When incident light 1135 acts on the surface 1137 of such a VMJ 1110, a plurality of electrodes for electrolysis in the form of anodes and / or cathodes can be formed through VMJ and / or on its surface 1137. The current flowing between such electrolysis electrodes that are formed on surface 1137 then passes through water and decomposes water into hydrogen and oxygen where a threshold voltage value is reached electrolysis Ia. VMJ 1110 includes a plurality of individual elements 1111, 1117 connected together (1 to n, where n is an integer), where such individual elements themselves are formed from stacked substrates or layers (not shown). For example, each individual element 1111, 1117 may include a plurality of parallel semiconductor substrates, stacked together and consisting of impurity-doped semiconductor material that forms a PN junction and an “built-in” electrostatic drift field that increases the low carrier velocity in the direction of such a PN junction. When the incident light 1135 is directed to the surface 1137 in various areas of the VMJ 1110, then a plurality of cathodes and anodes can be formed, which then act as electrodes for the electrolysis process.

The current passing through such electrodes for electrolysis passes through the electrolyte and decomposes the water into hydrogen and oxygen, when the threshold value of the electrolysis voltage is reached. Typically, such a decomposition threshold is in the range of 1.18 volts to 1.6 volts to break down water and create hydrogen and oxygen. It should be appreciated that higher voltage values can be achieved by adding up a plurality of individual elements (e.g., a plurality of elements connected in series). In addition, catalyst materials can also be used to increase the efficiency of hydrogen and oxygen formation and reduce corrosion of semiconductors caused by high electrode potential and electrolyte solutions. Moreover, the electrolyte can be formed from any solution and does not adversely affect the folded layers that form the VMJ element (for example, an iridium-based catalyst made from iridium, its two-component alloy or its oxide). In related aspects, ultrasonic transducers may interact with the electrolysis system to release oxygen or hydrogen bubbles that remain attached to the electrolysis electrodes.

The VMJ 1110 may also be located in a heating control unit 1119 that removes the generated heat from the hotspot areas to maintain a temperature deviation level for the VMJ element within preset levels. Such a heating control unit 1119 may be in the form of a heat sink structure that includes a plurality of heat sinks from a surface mounted on the rear side of the VMJ, where each heat sink may also include a plurality of fins (not shown) extending substantially perpendicular to the rear side. The fins can increase the surface area of the heat sink to increase contact with a cooling agent (for example, an electrolyte, a cooling liquid such as water), which can then be used to dissipate heat from the fins and / or photovoltaic cells. Thus, heat from VMJ can be transferred through a heat sink to the surrounding electrolyte, and / or a substance that does not affect the electrolysis process. Moreover, heat from the VMJ cell can be transferred through heat-conducting paths (e.g., metal layers) to the heat sinks in order to reduce the direct physical and thermal transfer of heat sinks to the VMJ cells and provide a scalable solution to ensure a normal electrolysis process.

In a related aspect, the heat sinks can be located in various planar or three-dimensional structures to control, regulate and, above all, to remove heat from the VMJ element. Moreover, each heat sink can also use heat / electrical structures (not shown), which can take the form of a spiral, twisted, screw, similar to a labyrinth or other structural form with a dense distribution of line structures in one part and a relatively less dense distribution of line structures in other parts. For example, one part of such structures can be formed from a material that provides relatively high isotropic conductivity, and another part can be formed from a material that provides high thermal conductivity in the other direction. Accordingly, each heat / electrical structure of the heat regulating installation provides a heat-conducting path that can dissipate heat from hot spots and transfer it to various heat-conducting layers or associated heat sinks of the heating control device, and thus contributes to the electrolysis process. It should be appreciated that the heat sinks can be cooled using an independent cooling agent that is separated from the electrolyte material.

12 depicts another aspect of the present invention, which includes protruding parts 1211, 1215 of metal layers that are connected to the electrodes of one separate element 1201. Such protruding parts 1211, 1215 protrude (for example, a few millimeters) from the surface 1241 of the VMJ 1200 to facilitate electrolysis process by increasing the contact surface area. In addition, very thin layers of electrical catalyst materials, such as platinum, RuO ₂ or titanium, can be incorporated into the metal coating during the manufacturing of the VMJ cell to increase hydrogen production. Moreover, there is a good opportunity to choose an electric catalyst material, since the n negative (-) side 1211 of the metal coating may differ from the p + positive (+) side 1215. It should be appreciated that one skilled in the art can easily select catalyst materials that will increase hydrogen production and are stable and compatible with the production of VMJ element. When the incident light 1235 reaches the VMJ surface 1241, a plurality of cathodes / anodes can be formed on it. For example, in the VMJ region with a negatively charged cathode, a reduction reaction takes place, and the electrons (e ^- ) from the cathode are transferred to hydrogen cations with the formation of hydrogen gas (part of the reaction is balanced by acid):

Cathode (reduction): 2H ⁺ (aq) + 2e ^- → H ₂ (g)

An oxidation reaction occurs on a positively charged anode, generating gaseous oxygen and transferring electrons to the cathode to close the loop:

Anode (oxidation): 2H ₂ O (l) → O ₂ (g) + 4H ⁺ (aq) + 4e ^-

The same parts of the reaction can be balanced with a base as indicated below. In general, not all parts of the reaction must be balanced by acid or base. In general, to add up the reaction parts, they usually need to be balanced with either acid or base:

Cathode (reduction): 2H ₂ O (l) + 2e ^- → H ₂ (g) + 2OH ^- (aq)

Anode (oxidation): 4OH ^- (aq) → O ₂ (g) + 2H ₂ O (l) + 4e ^-

The combination of both parts of the reactions leads to the same complete decomposition of water into hydrogen and oxygen:

Complete reaction: 2H ₂ O (l) → 2H ₂ (g) + O ₂ (g)

As indicated above, the number of hydrogen molecules produced is thus twice the number of oxygen molecules. Under the condition of equal temperature and pressure for both gases, the resulting gaseous hydrogen thus has a volume twice as large as the obtained gaseous oxygen. The number of electrons passing through water is two times the number of generated hydrogen molecules and four times the number of generated oxygen molecules. As explained previously, if a water-soluble electrolyte is added, the conductivity of the water increases significantly. Accordingly, the electrolyte dissociates into cations and anions, where the anions move toward the anode and neutralize the accumulation of positively charged H ^{+ there} ; similarly, cations move toward the cathode and there they neutralize the accumulation of negatively charged OH ^- . This makes possible the continuous flow of electric current. It should be estimated that the choice of electrolyte should be made taking into account the material used in the VMJ cell, so as not to have an adverse effect on its material and work. Additional factors in the choice of electrolyte relate to the fact that the electrolyte anion competes with hydroxide in terms of electron return. An anion of an electrolyte with a lower value of the normal electrode potential compared to hydroxide will most likely be oxidized instead of hydroxide, and therefore gaseous oxygen will not be produced. Similarly, a cation with a larger value of the normal electrode potential than that of the hydroxide ion will be reduced, and hydrogen gas will not be obtained. To exclude such circumstances, the following cations have a lower value of the normal electrode potential than H ⁺ , and thus are suitable for use as electrolyte cations: Li ⁺ , Rb ⁺ , K ⁺ , Cs ⁺ , Ba ²⁺ , Sr ²⁺ , Ca ²⁺ , Na ⁺ and Mg ²⁺ . Sodium and lithium can also be used if this does not adversely affect the VMJ element, since they form inexpensive soluble salts.

13 is a graph of voltage versus distance for VMJ 1310, where the individual elements 1311, 1317 intersect or share a common boundary. As depicted, VMJ 1310 includes many individual elements 1311, 1317 that are connected in series, in which the voltage can increase as a linear function of the number of elements that are stacked together (for example, from left to right along the horizontal axis). As shown in FIG. 13, the voltage difference between both ends of the element ₁ is 0.6 volts, and by applying element _{2 to it,} this voltage difference in the combined elements will increase to 1.2 volts. Similarly, by applying element ₃ to them, the voltage difference can be increased to 1.8 volts. Thus, electrolysis can occur between any two points on the surface of the VMJ, where the threshold voltage value for water decomposition is exceeded. For example, for an open loop, a voltage of 40 transitions of a VMJ cell at 1000 solar intensities of 32 volts can be obtained (for example, 0.8 volts on a single cell). Assuming that electrolysis begins at 1.6 volts, only two separate cells are needed to provide voltage. In another aspect, as the current load increases, the voltage determined by the current-voltage characteristic of the VMJ cell at maximum power at 1000 solar radiation intensities drops to 24 volts, or 0.6 volts on a single cell. Thus, three separate cells may be needed, corresponding to 1.8 volts to power the electrolysis reaction. (Typically, higher voltage may also be required for electrolysis at high current densities.)

Further, it should be appreciated that although electrolysis is described in the context of using a single VMJ, the present invention is not limited thereto and can be applied as part of a plurality of VMJ cells (e.g., parallel or series connected, or operating separately from each other). By determining the current dependencies formed in different areas of the VMJ, which exhibit different voltages, it is possible to select the design of the VMJ element to provide an additional contact area for handling large currents, where necessary. For example, contact current densities can be reduced by increasing the thickness of the metal coating at various points, if desired. Moreover, various types of pressurization can be applied to increase the electrolysis efficiency and / or to obtain (for example, by means of screening devices, filtration devices and the like) decomposition products (eg, hydrogen, oxygen). It should be appreciated that this invention is not limited to the electrolysis of water, and the electrolysis of other mixtures that are compatible with VMJ is within the scope of this invention.

FIG. 14 depicts a related process 1400 for electrolyzing water by a VMJ in accordance with an aspect of the present invention. While the exemplary method is depicted and described herein as a sequence of blocks representing various events and / or actions, the present invention is not limited to the illustrated order of such blocks. For example, some actions or events may occur in different sequences and / or simultaneously with other actions or events, in contrast to the sequence depicted here, in accordance with the invention. In addition, not all illustrated blocks, events, or actions may be required to apply the method in accordance with this invention. Moreover, it will be appreciated that the exemplary method and other methods in accordance with the invention can be applied in connection with the method depicted and described here, as well as in connection with other systems and installations not shown or not described. First, at step 1410, the electrolyte solution is introduced into a container that contains a VMJ, where it is completely or mostly immersed. Such a system is then exposed to incident light at step 1420, and the current generated by VMJ flows. Incident light can generate water electrolysis through an electrolyte solution at step 1430, and at any point where a threshold value for water decomposition is reached or exceeded (e.g., about 1.2 volts), electrolysis occurs. For example, a voltage of 0.6 volts can be generated on each individual cell (for example, for 1000 solar radiation intensities), and electrolysis can occur between the regions of the first individual cell and the third individual cell. Accordingly, various collection devices (e.g., membranes, grating plates, and the like) can be located between regions where the voltage exceeds a threshold value for electrolysis (e.g., about 1.6 volts), and thus collect the resulting hydrogen gas step 1440. It should also be appreciated that other collection devices, such as downstream collection, are also possible.

15 shows a VMJ cell that can be used for electrolysis in accordance with an aspect of the present invention. VMJ 1515 itself is formed from a plurality of individual elements 1511, 1517 connected together (from 1 to n, where n is an integer), where each individual element itself is formed from stacked substrates or layers (not shown). For example, each individual element 1511, 1517 may include a plurality of parallel semiconductor substrates folded together and consisting of impurity-doped semiconductor material that forms a PN junction and an “built-in” electrostatic drift field that increases the low carrier velocity in the direction of such PN junctions. Moreover, by using the buffer (s) zones (s) 1510, 1512, various active layers, such as with nn + and / or p + n junctions located at both ends of the VMJ element 1515 (and which are part of its individual elements), can be protected from adverse types of pressure and / or tension (for example, from thermal / mechanical compression, twisting, stress, deformation, and the like, which can be applied to the VMJ during its production and / or operation). Each of these buffer zones 1510, 1512 can be formed using a material that has an ohmic contact of very low resistance (for example, in any interval with an upper boundary of less than about 0.5 Ohm per cm), while reducing and / or eliminating undesirable auto-alloying. For example, buffer zones 1510, 1512 can be formed by using p-type alloyed low-resistance plates with other p-type impurities, such as aluminum alloys, to reduce the possibility of self-alloying (compared to using n-type plates, which can create unwanted pn junctions when it is desirable to create ohmic contacts of very low resistance). Catalyst materials (e.g., platinum, titanium and the like) can also be used at the VMJ terminal contacts to facilitate the electrolysis process, for example.

16 depicts a separate aspect of an individual element 1600, the structure of which can form a VMJ element. Separate element 1600 includes layers 1611, 1613, 1615, folded together in an almost parallel structure. Such layers 1611, 1613, 1615 may also include impurity-doped semiconductor material, where layer 1613 is a layer of one type of electrical conductivity and layer 1611 is a layer of the opposite type of electrical conductivity to determine the PN junction at junction 1612. Also, layer 1615 can be a layer of the same such as electrical conductivity as layer 1613, but with a significantly higher concentration of impurities, thus generating a “built-in” electrostatic drift field, which increases the low velocity of carriers in the direction and PN transition 1612. These separate elements may be joined together to form a VMJ (e.g., using the catalyst material for such communication to enhance electrolysis), which carries out the electrolysis as described in detail above.

In accordance with another aspect, in order to produce a VMJ from a plurality of elements 1600, initially the same PNN + (or NPP +) junctions can be formed at a depth of about 3 to 10 μm in high-resistance silicon flat wafers (e.g., more than 100 ohms per cm) N type (or P type) having a thickness of about 0.008 inches. Further, such PNN + plates are folded together with a thin layer of aluminum located between them, where the PNN + transition and the crystalline orientation of each plate can be directed in the same direction. Moreover, aluminum-silicon fusible alloys can be used, or metals, such as germanium and titanium, or metals, such as molybdenum or tungsten, which have thermal coefficient (s) that practically coincide with the thermal coefficient of silicon. Further, the surfaces of silicon wafers and aluminum alloys can be fused together so that the superimposed structure can be joined (for example, also including a catalyst material). It should be appreciated that other material, such as germanium or tungsten, may also be used. Also, aluminum-silicon fusible alloys can also be used. It should also be estimated that the electrolyte should be selected so that it does not adversely affect the operation of the VMJ and / or leads to chemical reactions that are harmful to the VMJ. It should be appreciated that various doped layers of N + -type and P-type can be used as parts of individual elements, and such structures are included in the scope of this invention.

17 depicts a further aspect of the present invention, which includes a textured surface VMJ used for electrolysis. A schematic perspective view of a grooved surface 1700 is depicted as part of a multi-junction (VMJ) vertical transition element 1720 in accordance with an aspect of the present invention. Such a structure for structuring 1700 allows the refracted light to be directed from the p + and n + diffuse doped regions, while at the same time the desired carriers are created. Accordingly, incident light can be refracted in a plane 1710 having a normal vector n. Such a plane 1710 is parallel to the PN junction planes of the VMJ 1720 and may include a configuration with a cross section of grooves 1700. In other words, the orientation of the plane 1710 is practically perpendicular to the direction of application of the individual elements 1711, 1713, 1715. Such a grooved surface can increase the efficiency of the electrolysis process.

Fig. 18 depicts exemplary groove textures on a VMJ surface that receives light for electrolyte electrolysis. Such grooves can be in the form of grooves of a deepened shape, for example, such as a configuration with a cross section in the shape of “V” having different angles θ (for example, 0 ° <θ <180 °) of a configuration with a cross section in the shape of “U” and similar, where a plane that includes a cross-sectional configuration is substantially perpendicular to the direction of application of the individual elements that form the VMJ and / or substantially parallel to the PN junctions of the VMJ. It should be appreciated that the texturing 1810, 1820, 1830 for the VMJ of the present invention is different from the textures of conventional silicon photovoltaic cells known in the art in the field of orientation of PN junctions and / or interaction with incident light. For example, traditional silicon photovoltaic cells are typically textured so as to deflect penetrating light so that more waves having a longer wavelength are absorbed closer to the PN junctions (horizontally) for better current collection by carriers, and therefore mitigate low spectral sensitivity to large wavelengths in the spectrum of solar radiation. Conversely, this is not required in the VMJ of the present invention, which includes vertical transitions and, therefore, already provides increased spectral sensitivity to longer waves in the spectrum of solar radiation.

Preferably, one aspect of the use of the grooves of FIG. 7 (for example, V-grooves) is to reduce the bulk of the recombination losses by reducing the bulk of the main portion (compared to surfaces of traditional solar cells with a texture that reduces reflection or approximates reflected or refracted light to transitions). In particular, the VMJ element demonstrated the best carrier current collection for both short wavelengths and long wavelengths, where sensitivity to short wavelengths is observed due to the exclusion of heavily doped horizontal transitions on the upper surface, and sensitivity to long wavelengths is observed due to the increased the efficiency of collecting vertical transitions. As another example, if instead of the structure of the grooves of the deepened shape in accordance with this invention, other textures (for example, with a random, pyramidal, domed or similar protruding configuration) would be used as part of the VMJ, the incident light would begin to refract in all directions, which led would to light absorption in p + and n + diffuse regions and, consequently, to reduced efficiency. Moreover, reflective coatings can be applied to the rear surface of the VMJ element to further enhance light absorption.

In another aspect, this invention relates to an increased efficiency of photovoltaic cells, for example, solar cells, in particular high intensity solar cells, such as illuminated from the edge of a structure or structures with vertical transitions, which can have a significant high output power at high levels of radiation intensity. Various designs of PV elements that form the individual elements used to produce VMJ photovoltaic cells are proposed here to reduce the recombination losses of photogenerated carriers using structured contacts.

The VMJ element has a theoretical value of its own efficiency limit exceeding 30% at 1000 solar radiation intensities, so further performance improvements are possible with experimental understanding and understanding of the essence from the analysis of simulations and computer simulations. Although traditional solar cells, calculated on the same intensity of solar radiation, can easily be modeled with good results using analytical equations, this is not suitable for elements illuminated from the edge of the VMJ operating at high intensities, since at high intensities even second-order effects can have significant ( s) the impact (s) on the performance of the element. While aspects or features of the present invention are depicted with solar cells, such aspects or features and related advantages, such as reducing the recombination losses of photogenerated carriers, can be used in other photovoltaic cells, for example, thermophotovoltaic cells, or cells excited laser (s) source (s) of photons. Moreover, aspects of the present invention can also be used in other classes of energy converting elements, such as beta-electric elements.

The physics of a pair of electron-hole carriers obtained in solar cells at high intensities is rather complicated, since many physical parameters are involved, including, but not limited to: surface recombination rates, carrier mobility and concentration, reverse saturation currents of emitters (e.g., scattering) , life spans of minority carriers, narrowing of the forbidden energy zone, built-in electrostatic fields and various recombination mechanisms. Mobility decreases sharply with increasing carrier density, and Auger recombination sharply increases with intensity in a cubic dependence on carrier density. To include such aspects in modeling the performance of a VMJ solar cell, computer simulations (for example, two-dimensional numerical computer analysis of the movement of a photogenerated carrier in a semiconductor) can provide an understanding of the essence of the physical parameters of individual elements with vertical transitions, or PV elements operating at high intensities. Such simulations provide the opportunity for analysis and development to understand the possible sources of performance efficiency and increase the performance of VMJ elements at high intensities. It should be appreciated that although traditional solar cells for working at the same intensity of solar radiation can easily be modeled with good results using simple analytical equations, this is not suitable for edge-illuminated photoelectric VMJ cells operating at high light intensities, since at high intensities even second-order effects can have a significant impact on the performance of an element.

Computer simulations are based on models of individual elements located contact to contact VMJ, which are included in the structure of semiconductor physics-specific regions in VMJ individual elements, where the recombination losses of photogenerated carriers occur at high intensities. At least some of these areas present complex loss mechanisms that depend on intensity. Computer simulation (s) displays areas in PV elements or VMJ individual elements that can be improved to reduce recombination losses and increase the performance of VMJ elements. Aspects of the present invention provide such improvements.

Series resistance was considered an essential source for developing solutions for traditional solar cell concentrators. The design of the VMJ photovoltaic cell proved to be more than worthy in this regard, demonstrating that the series resistance is not a problem even at 2500 solar radiation intensities. Nevertheless, in some cases it may be advantageous to compromise and increase the resistance of the series connection in order to reduce design complexity in order to increase the efficiency of the VMJ photovoltaic cells for photovoltaic concentrators operating at about 1000 solar radiation intensities.

It should be estimated that a design for operation at significantly higher intensities, such as 2500 solar intensities, where the VMJ elements are still able to work efficiently, may require a significantly whiter demanding and expensive development of a concentrator system in the fields of optics, structures, solar supply and thermal regulation, while most likely not improving overall productivity or profitability. Thus, aspects or features of solar cells and their associated production process (s) proposed in this invention can increase the performance of high intensity VMJ cells operating in the range of 1000 solar intensities or higher. Increased efficiency can make VMJ solar cells or other solar cells that incorporate aspects of the present invention more cost effective and viable, even though this can lead to additional manufacturing operations and a potential increase in series resistance for intensities greater than 1000 intensities of solar radiation. The aspects and features described herein can provide appropriate design tradeoffs to make solar cell systems, solar cells, VMJ cells or anything where aspects of the present invention are used more viable and cost effective by providing performance with more low rate of $ / watt.

Analysis of computer simulation of the design of a traditional VMJ single element, for example, a P + NN + plate with deep transitions, using real parameters for good silicon processing (lifetime of minority carriers, surface recombination rate, etc.) at intensities of more than 500 solar radiation intensities, demonstrated the following recombination loss percentages for some selected areas:

P + diffusion 22.7%

P + contact 5.3%

N + diffusion 32.8%

N + contact 11.4%

Thus, this analysis suggests that heavily doped P + and N + diffuse radiation regions with their metal contacts are responsible for more than half of all recombination losses in the individual elements that form the VMJ solar cell, and that the optimized diffuse N + emitter may differ in design from the optimal diffuse P + emitter, partly due to the difference in mobility. The relative value of the recombination losses occurring in the N + and P + regions can be changed for N + PP + of the individual element (s) or P + NN + of the individual element (s) with the surface (s) P + N junction (s) ) In an aspect, the present invention is directed to reducing recombination losses in the following diffuse regions in order to improve the performance of VMJ cells.

High lifetimes of minority carriers and low surface recombination rates were successfully achieved when developing a traditional VMJ cell with an open circuit voltage V _oc = 0.8 volts per transition of a single cell at high intensities. V _{oc is} determined by the currents generated by sunlight and the return saturation currents of the diffuse emitters (J _o ), in the presence of both P + N and NN + junctions in the individual solar cell element (s) VMJ, which form part of the open circuit voltage. Optimal transitions from the electrical point of view have the smallest value of J _o ; when using J _o = 1x10 ^-13 Asm ^-2 , which is typical for low values of high-quality reverse saturation currents in diffuse transitions, analysis showed that diffuse depths of the order of 3 to 10 μm are sufficient depths for both P + and N + diffusions , even when taking infinite recombination rates at ohmic metal contacts.

It should be noted that even though deep and gradual NN + diffusion profiles will provide a built-in electrostatic drift field that increases the low velocity of carriers in the direction of the transition barrier for the maximum possible collection and reduction of recombination in this region, computer simulations show that an increase in the NN + transition becomes less effective at higher intensities, which can lead to greater recombination in the N + region, as shown above.

Experiments and computer simulations and simulations have determined that the best areas for improving performance relate to the reduction of recombination losses in the areas of heavily doped P + and N + diffuse and metal contacts for the operation of VMJ individual elements at high intensities. Since a high-quality oxide passivated surface can have a low recombination rate of several cm / second, which is significantly lower than that of metal contacts, and assuming that the drift fields created by diffuse profiles become less effective at high intensities, aspects of this invention provide reduced metal contact area and diffuse area through a structured dielectric coating of PV elements, or VMJ individual elements, to improve the performance VMJ solar cell performance.

With reference to the drawings, FIG. 19A shows a circuit 1900 of a photovoltaic cell 1910 with a structured dielectric coating 1920 between one of the surfaces of the PV element and the metal contact 1925. Note that the surfaces of the PV element 1910, the dielectric coating 1920 and the metal contact 1925 are not in contact for clarity. However, in the solar cell (s) considered here, such surfaces are in contact. The structured dielectric coating 1920 is depicted as disjoint elliptical regions assembled into a periodic structure or lattice. The PV element 1910 is usually a plate of N-type semiconductor material, where the semiconductor material is one of Si, Ge, GaAs, InAs or another semiconductor compound of group III-V, semiconductor compound of group II-VI, CuGaSe, CuInSe, CuInGaSe. The plate may include a doped P + diffuse region 1916 (denoted by P +) on the first surface of the plate and a doped N + diffuse region 1914 (denoted by N +) on a second surface substantially parallel to the first surface. The thickness of the active PV element 1910 is provided by an N-type layer (N) 1912 between the diffuse alloyed layers 1914 and 1916. The thickness of the diffuse layers 1914 and 1916 can be in the range from 3 to 10 μm and is determined by the alloying process used to insert the carriers into the material plate N-type (e.g. plate 1912). The inclusion of diffuse alloyed layers can be accomplished using practically any alloying means, for example, technologies and alloying materials commonly used in the processing of semiconductors. Alloying materials may include phosphorus and boron for N + and P + alloying, respectively. For the purpose of explanation, the surfaces between the diffuse layers N + 1914 and P + 1916 b by the N-type (N) 1912 layer are idealized as a very rough interface; however, such surfaces may be non-standard, with mixing areas between neutral and alloyed materials. The degree of mixing is determined, at least in part, by the mechanism or means used to produce doped diffuse regions.

While aspects or features of the present invention are depicted for an N-type initial wafer of semiconductor material as a starting element of a PV element 1910, such aspects and features can also be applied or performed in an initial internal, for example, nominally non-alloyed, starting element of a PV element 1910 Moreover, in alternative or additional embodiments, the initial P-type element (s) may be used: PV element 1910 may be a plate of doped P-type semiconductor material, which which may include a P + diffuse layer 1916 on and near the first surface of the plate and an N + doped diffuse layer 1914 on and near the second surface substantially parallel to the first surface, as described above.

In an aspect of the present invention, structured dielectric coating 1920 reduces the formation of a metal bonding surface and a diffuse alloy layer (e.g., a metal bonding surface and an N + layer 1914) on a metal coating of an active PV element 1910, the holes in the structured dielectric coating are regions where the metal and diffuse alloy layer form the connection surface. Since such compound surfaces have high recombination losses, a decrease in the contact of the metal and the diffuse doped layer, thus, reduces losses of photogenerated carriers (for example, electrons or holes) that are not related to radiation, with this increase in the photoelectric efficiency of the PV element 1910. In addition , coating the PV element 1910, for example, with a dielectric material, forms a passivation of surface states and, thus, reduces surface recombination losses. Structuring of the dielectric coating can be carried out by means of photolithographic technologies or almost any other technology that makes it possible to regulate the structuring of the dielectric surface, for example, by wet etching. Such photolithographic technologies usually carry out the formation of a structure as a result of many production steps of masking and removing the dielectric material in the dielectric coating. Alternatively or additionally, the coating can be structured using deposition techniques, for example, vapor deposition, such as chemical vapor deposition (CVD) and its variations, plasma enhanced CVD (PECVD), molecular beam epitaxy (MBE), and etc., in the presence of a mask that covers the deposited material in order to define a special structure.

It should be appreciated that the dielectric coating layer 1920 can take on various planar structures and configurations that provide electrical contact between the N + doped diffuse layer 1914 and the metal contact 1925. As indicated above, in the exemplary circuit 1920, the dielectric coating 1920 adopts a square lattice structure of elliptical disconnected areas. Other dielectric gratings may also be formed. Such gratings may include a triangular grating, a monoclinic grating, a face-centered square grating, or the like. Alternative or additional structures of the dielectric material part (s) within the structured dielectric coating may include disconnected or connected strips of dielectric material. It should be noted that a structured dielectric coating, such as coating 1920, can be located between the metal contact 1935 and the P + diffuse doped layer 1916 (see, for example, FIG. 19B). The position of the structured dielectric coating 1920 is determined by a neutral-doped junction, which has the main losses during the working radiation intensity in a solar concentrator or other installation or device for converting solar electricity. For example, in a PV element 1910 (for example, P + NN + a separate element), the N + diffuse region, or layer, and its contacts with the metal 1925 can have significantly greater losses at high electromagnetic radiation intensities, thus, the structured dielectric coating 1920 in the configuration depicted 1900 may have a significantly less expensive configuration to reduce recombination losses (for example, associated with radiation or not related to radiation) and improve the performance of the PV element 1910, especially at high intensities.

It should be appreciated that almost any structure of the dielectric material (for example, a disconnected hole structure, such as the space between the dielectric elliptical regions in the dielectric coating 1920) can reduce the recombination losses in one diffuse layer (for example, N + layer 1914), since the metal coating applied at a later stage, it can guarantee that all or almost all open contact areas are mutually connected when fully connected to the next flat individual element in the jet round VMJ element. The individual element (s) used (e) for the production of the VMJ photovoltaic cell, as described herein, consists of a PV element 1910 coated with a dielectric structure and metallized as described above. Thus, such individual element (s) is (are) different from the traditional individual element (s) used (s) for the production of traditional VMJ solar cells. It is noted that the smaller (s) contact region (s) between the metal and the alloyed layer (gut) can lead to an increase in the resistance of the series connection of the block of PV elements, such as 1910, which forms the solar cell; thus, the advantageous structure for reducing the relative value of the contact area is a high concentration of closely spaced smaller holes to optimize performance for a given intensity. Recombination losses may include radiation-related and non-radiation-related recombination of photogenerated carriers, where non-radiation-related recombination may include Auger scattering, relaxation of a phonon carrier, or the like. Auger recombination rate increases in a cubic dependence on the density of carriers, for example, the density of photogenerated carriers; a twofold increase in the volume of the photovoltaic device can lead to a sixteen-fold increase in recombination losses when the main Auger scattering is taken into account. Thus, thinner plates 1910 or almost any structural modification that makes the PV element 1910 thinner, such as the use of light-collecting structures with textured surfaces such as surfaces with grooves in the shape of V, surfaces with grooves in the shape of U .. ., or reflectors on the rear side, can be used to reduce the bulk of Auger recombination at high densities by reducing the thickness of the individual cells that form the VMJ photovoltaic cell. The removal efficiency in PV elements can increase significantly when VMJ individual elements, which are designed in accordance with the aspects described here, provide a 50% reduction in recombination losses.

It should be appreciated that virtually any dielectric material can be used for dielectric coating 1920. In an aspect, the dielectric coating can be a layer of thermally formed oxide that has a low surface recombination rate. It should also be appreciated that by placing electrical contacts at the end of a single element or PV elements made on the basis of semiconductors (for example, based on Si) of VMJ photovoltaic cells with structured holes in the dielectric, a full electrical contact may be required, which can be provided using silicon low resistance, which thermally coincides or practically coincides with the coefficient of thermal expansion of individual elements, or a metal, such as molybdenum or tungsten, which have m Thermal (s) factor (s) that (e) is almost identical (dissolved) with thermal (to) coefficient (Ami) silicon. Similarly, for a VMJ solar cell based on a semiconductor material or structure other than silicon, the metallization of a structured dielectric coating, for example 1920 or 1960, can be carried out by the conductive material (s), for example, metals or alloyed semiconductors of low resistance, which have a coefficient (s) of thermal expansion, which (e) practically coincides (s) with the thermal (s) coefficient (s) of the semiconductor material of the individual elements that form the VMJ solar cells ents.

With reference to the metal layers, the metal contact layer 1925 and the metal contact layer 1935 may be different. For example, the first metal contact layer (e.g., layer 1925) may include dopants, and the second contact layer (e.g., layer 1935) may include a diffuse barrier to prevent auto-alloying.

19B is a 1950 diagram of a photovoltaic cell 1910 with structured coatings in both diffuse doped regions. In 1950, the first structured dielectric coating 1920 is located between the N + diffuse alloyed layer 1914 and the first metal contact 1925, and the second structured dielectric coating 1960 is located between the P + diffuse alloyed layer 1916 and the second metal contact 1935. The aspects of the dielectric coating 1960 are practically the same as dielectric coating 1920. As mentioned above, the layers of metal contact 1925 and 1935 may be different.

It should be noted that the decrease in the recombination losses of photogenerated carriers and the associated increase in the efficiency of the PV element, provided by the introduction of a second structured dielectric coating, are more significant compared with the additional complexity and possible additional costs for the additional production step (s) associated with the preparation a second structured dielectric coating.

In order to guarantee the effective operation of the PV element 1910 in the photovoltaic device, the first structure in the dielectric coating 1920 must be correlated with the second structure in the coating 1960 so as to have a set of one or more opening (s) and, on the other hand, sections (s) metal layers 1925. When the structured dielectric coating 1920 is “phase shifted” relative to the structured dielectric coating 1960 and the dielectric coatings mutually cover the section (s) of the respective metal layers On October 1925, the resistance of individual cells in the PV unit 1910 increases, and the efficiency of the VMJ solar cell decreases.

Additionally or alternatively, the holes formed through the structured dielectric coating 1920 may have a different size, for example, the different area occupied by the holes in the dielectric coating 1960. For example, it may be more desirable to have a hole area wider for N + contacts than for P + contacts in the PV element 1910 or P + NN + individual elements in order to more effectively reduce the total loss, in particular, if there are higher losses in the N + diffuse region and metal contacts. As described above, such a difference in hole sizes can be used or applied regardless of the specific structure of the dielectric coating.

Fig. 19C is a diagram of an exemplary set of starting elements and the resulting PV element (s) that (e) can (gut) be produced (s) by alloying in accordance with the aspects described herein. As indicated above, three types of starting elements (precursors) can be used to produce PV elements that are processed to obtain structured dielectric coating (s) and metallic (s) contact (s), as described herein : (I) an N-type doped starting element 1980, (II) a P-type doped starting element 1985 and (III) an intrinsic semiconductor starting element 1990. The starting elements are semiconductor materials such as Si, Ge, GaAs, InAs, or other semiconductor compounds of group III-V, semiconductor group II-VI hydrated compounds, CuGaSe, CuInSe, CuInGaSe. After doping, an N-type starting element 1980 can become a 1982 FE element, which includes a diffuse doped N + type region and a P + type doping region, such a FE element is a 1910 FE element. In addition, doping of the 1980 starting element can lead to a 1984 FE element , with layers or regions of diffuse alloying of N-type and P-type. The starting element 1985 makes it possible to form PV elements of 1986 and 1988 with N + and P + diffuse doped layers in the PV element 1986 and N + by diffusing alloying and P-type alloying in the element 1988. Different alloying of the starting element from the 1990 semiconductor results in obtaining PV elements 1992- 1998. In the FE element 1992, the P-type and N-type doping regions are included, the 1994 FE element includes doped N + -type and P-type layers, the 1996 FE element includes doped N-type and P + -type layers, and N + -type and P + layers -types are included in the FE element 1998. While the various doping regions introduced into the materials of the starting elements 1980, 1985 and 1990 are depicted by elongated regions, such regions can be spatially bounded or practically bounded, as described here. The various PV elements depicted here may be coated with a structured dielectric material and metallized as described herein to form a separate element (s) that (e) can fold to form a single (monolithic) photoelectric element in in accordance with aspects of the present invention. In an aspect, structured contacts formed by applying a structured dielectric material to P + NN + PV elements or individual elements can be used for terrestrial PV concentrators, while P + PN + PV elements or individual cells can be more resistant to radiation and, thus, can be used for space applications.

20A is a 2000 cross-sectional diagram of a PV element with one structured surface with a dielectric coating. As a result of the structure of the dielectric material, the dielectric sections 2005 are deposited on the N + diffuse doped layer 2014. It should be noted that an additional or alternative configuration of the PV element with a structured dielectric coating on the P + diffuse doped layer 2016 is possible. In the PV element shown in diagram 2000, the N-type region 2012 separates the diffuse doped regions 2014 and 2016. As discussed above, this configuration can be effective in reducing the recombination losses associated with the operation of the PV element at high intensity.

Fig. 20B depicts a PV element of a circuit 2030 after metallization with metal contacts 2025 and 2035. The presence of regions of structured dielectric coating 2005 on the N + diffuse layer 2014 reduces the electrical connection between the electrical contacts 2025 and 2035. As discussed above, the layers of metal contacts can be different.

Fig. 20C depicts an exemplary embodiment of a VMJ photovoltaic cell 2060, where the long individual cells 2070 ₁ -2070 _M (M is an integer) superimposed along the direction 2080 use a one-way asymmetric structured dielectric coating (e.g., a coating with dielectric regions 2005) on N + diffuse alloyed layer. VMJ solar cell, which is obtained from a block of individual elements 2070 _λ (λ = 1, 2 ... M), which are PV elements, is a single (for example, connected together) structure along the axis. In an aspect, based on the semiconductor material of the individual element (s), two classes of VMJ photovoltaic cells can be formed: (a) homogeneous and (b) heterogeneous. In (a), separate (e) element (s) 2070 ₁ - 2070 _{M is} based (s) on the same source elements, while in (b) separate (e) element (s) is based (s) on different source elements . Different initial elements can be based on the same semiconductor structures, for example, Si, Ge, GaAs, InAs or other semiconductor structures of III-V groups, semiconductor structures of II-VI groups, CuGaSe, CuInSe, CuInGaSe, but differ in the type of doping or, for structures alloys, alloy concentration. Inhomogeneous VMJ photovoltaic cells can involve various parts of the radiation spectrum of an electromagnetic radiation source, for example, the radiation spectrum of sunlight. The VMJ solar cell can produce a series voltage ΔV≈M ∙ ΔV _c along the direction of 2080, where ΔV _c is the voltage in the PV component of the 2070 _λ cell. In an aspect, M ~ 40 is commonly used to form a VMJ solar cell. 1 cm ² VMJ with M ~ 40 may provide approximately 25 volts under normal operating conditions such as the incident photon flux, wavelength, temperature and the like. It should be appreciated that the performance of the block of PV elements is limited by the PV elements with the lowest productivity, since such an element is a bottleneck in a serial connection when current is generated; that is, the current output decreases to the current output value of an individual element with the lowest productivity. Thus, in order to optimize the performance, the blocks of active PV elements or individual elements that form the VMJ photovoltaic cell can be identical in current or practically identical in current based on the performance characteristics recorded on a test setup under conditions (e.g., wavelength (s) of radiation , degree of concentration), almost identical to those assumed under normal operating conditions of the solar collector system in the field. The current that matches is the current generated by the PV element or an individual element after the conversion of solar energy into electrical energy.

In addition, a single block of PV elements 2070 ₁ - 2070 _m , which forms a VMJ solar cell, can be processed, for example, sawn, cut, pickled, peeled or the like, in order to open or practically open a special crystal plane (qrs) with Miller indices q, r, s, which are integers, to sunlight, when the VMJ solar cell is part of a PV module or device. In an aspect, in order to achieve substantial passivation of surface states, the particular crystalline (s) plane (s) may (gut) be (100) planes. 20D depicts a VMJ PV element 2090 obtained by superimposing PV elements or individual elements 2092 with structured contacts in the form shown in FIG. 20C, the VMJ PV element is processed to open a particular crystalline surface (qrs) indicated by a normal vector 2094 directed to direction <qrs>. It is noted that any PV elements with structured contacts described here can be used to form a VMJ PV element that opens the crystal plane (qrs). In addition, as part of the processing and based on the <qrs> direction, part 2096 of the VMJ PV element can be removed to create a flat surface, to facilitate or make possible the use of the VMJ PV in the PV device or module.

Figa is a diagram that depicts examples of structures (s) of the dielectric coating of the PV element. Structures 2130 and 2140 relate to structures on the first and second surfaces of the PV element. The holes in the dielectric coating are lines or strips with a fixed width w 2135 and stepwise separation from each other w _p 2145. In an aspect, such a hole structure in a structured dielectric coating reduces the contact area by (1 + w / w _p ) ^-1 ; for example, when w = w _p , the decrease is 50% of the decrease in contact area. However, reducing the contact area can lead to an increase in the resistance of the series connection, the preferred structure of lines or strips to reduce the relative contact area has a high density of closely spaced holes in the form of small lines or strips. The density can be varied in order to optimize the performance for a given radiation intensity, at which the PV element supposedly works as part of the solar cell, the PV element in the PV module. Additional or alternative structures on opposite surfaces of the PV element 1910 or plate are also possible and are an advantage. As shown, holes in the form of lines or stripes can be made on opposite sides of each PV element 1910 or plate and are 90 degrees deflected from one side to the other; that is, the strips in the structured dielectric coating 2130 are oriented at an angle of 135 degrees with respect to the <100> direction, while the strips in the structured material 2140 are aligned at a 45 degree angle with respect to <100>. It is noted that other similar deviations are also possible and are an advantage. Moreover, as indicated above, the holes formed through the structured dielectric coating 2130 may vary in size, for example, within the different areas that the holes create in the dielectric coating 2140. For example, it may be more generally desirable to have hole areas for N + contacts wider than for P + contacts in a PV element with P + NN + separate element (s) (s) in order to more effectively reduce the overall losses, especially when there are large losses in the N + diffuse regions and metal contacts. Alternatively, it may be desirable to use the hole regions for the P + contacts wider than for the N + contacts in order to reduce the recombination loss in the N + PP + individual element (s) (e.g., PV element 1986).

In the manufacture of multi-junction (s) solar cell (s) with vertical transitions, which (s) include the addition and fusion of PV elements with structured surfaces described herein, dielectric regions with different orientations when connected to a metal coating can form contact points of low resistance in a given structure. In an aspect, the contact points facilitated by the holes in the dielectric coating 2130 and 2140 are directed straight along the line and are located close to each other in an adjustable structure with P + contacts of one plate connected at points with N + contacts of the next plate in order to maintain low resistance of the series connection in the finished VMJ elements. As described above, in an aspect, the manufactured VMJ elements can be sawn to have a preferred <100> crystalline orientation on the illuminated surface in order to establish lower degrees of surface passivation. Thus, as shown in FIG. 21A, the relative orientation of the lines or stripes on the first surface of the structured PV element can be relatively offset by an angle γ, such as 90 degrees, from the lines or stripes on the second surface, where the first and second surfaces include the direction of the crystals <100>, for example, normal to the crystalline plane (100). Other orientations of lines or stripes are also possible and are an advantage. Also, the relative displacement of γ lines and bands on different surfaces can be used. In an aspect, the bias γ is a certain real number; for example, dielectric coating structures are not mutually connected on different surfaces. In addition, since the VMJ photovoltaic cells described here can be processed to open or practically open any crystal plane (qrs), the strips in the dielectric coating can be oriented at an angle relative to the crystalline directions <qrs> with Miller indices q, r and s. In particular, the strips in the structured dielectric coating on the first surface may include strips oriented at the first angle α with respect to <qrs>, while the strips in the structured dielectric coating on the second surface can be oriented with the second angle β (α ≠ β) with respect to <qrs>, thus providing a bias of γ = α-β.

FIG. 21B is a cross-sectional view of a PV circuit of an element 2150 with dielectric coating structures located both on the P + diffuse doped layer 2176 and on the N + diffuse doped layer 2174. In the PV elements 2150, an N-type region 2172 separates the diffuse doped regions 2014 and 2016. The cross section shown is a slice that depicts the connection of dielectric regions on a first surface, for example, dielectric regions 2155, with dielectric regions on a second surface, for example dielectric regions 2165. It should be appreciated that other cross-sections of the slices can represent the unconnected regions of the dielectric material of the first surface and the second surface. As discussed above, this connection helps to maintain the resistance of the series connection in the PV cells 2150 when added to form the VMJ solar cell, since the metal contact of the P + diffuse alloyed layer can coincide with the metal contact of the N + diffuse alloyed layer superimposed below, as shown in Fig. 21C . It should be appreciated that, as indicated above, the space between the dielectric regions 2155 may differ from the space between the dielectric regions 2165.

FIG. 22 is a cross-sectional view of a circuit of an exemplary PV element 2200 with regions of a dielectric coating 2205 obtained by depositing a structured dielectric coating 2202 that contributes to or makes it possible to reduce at least a metal contact region on the surface of a PV element on its metal coating. In the PV element 2200 N +, the diffuse region (s) 2214 is structured (s) in order to reduce the volume of the doped layer and, thus, reduce the recombination losses of photogenerated carriers. N + regions can be defined by hole patterns in a structured dielectric coating; for example, the N + diffuse region (s) 2214 may (gut) be bands oriented along the step separation (s) in a structure with stripes of dielectric coating 2202. Such regions are formed by using regions of dielectric coating 2205 as a mask to adjust or control N + alloying. Based on at least a portion of the structured dielectric coating 2202 and the configuration of the deferred regions 2205, N + diffuse alloyed region (s) or volumes (s) 2214 can be completely limited or almost limited, for example, limited to two or smaller directions and passing in the third direction. In particular, the PV of element 2200 of the N-type material region 2212 is supplemented by N + diffuse doped regions 2214. In addition, the P + diffuse doping region 2216 is not coated with structured dielectric material.

After metallization, for example, after the P + diffuse layer 2216 and the structured surface of the limited disconnected N + diffuse alloyed region (for example, a set of regions 2214) are coated with a metal contact, a set of metallized PV elements can be joined and processed, for example, soldered or fused in step producing heat to form a VMJ photovoltaic cell with reduced recombination losses in accordance with aspects described herein.

FIG. 23A is a cross-sectional view of a PV circuit of an element 2300 with dielectric coating structures deposited on opposite diffuse alloyed regions. In an aspect, a first dielectric coating structure (for example, a structure with stripes 2330 oriented along a direction 135 degrees rotated relative to the crystalline direction <100>) is used to reduce the metal contact area in the first diffuse alloyed region, while the second dielectric coating structure (for example, a structure with stripes 2340 oriented at 45 degrees relative to the crystalline direction <100>). Both N + and P + diffuse doped regions can include respectively doped regions 2314 and 2316, limited in two or more directions. The holes in the structures of the dielectric coating can serve as masks for obtaining diffuse alloyed layers with a reduced volume; holes formed between regions 2305 and 2325 of the coated dielectric. The decrease in the surface of the metal contact and the volume of the doped regions for both diffuse doped layers can provide an improved decrease in the recombination losses of carriers with respect to the dielectric coating and a decrease in the doping of one doped region. As discussed earlier, the benefits of improved PV performance of VMJs produced with structured PV elements or individual elements are more significant compared to the additional manufacturing complexity and costs associated with surface structuring. Moreover, the holes formed in the structured dielectric coating 2330 may vary in size, for example, in different regions, from the holes formed in the dielectric coating 2340, in order to better control the recombination losses occurring in the diffuse doped regions. For example, it may be more desirable to have openings that provide large N + doped regions than those that provide P + doped regions in order to more effectively reduce overall losses, especially when large losses occur in the N + diffuse region and metal contacts.

Figv depicts a cross section of a structured PV element 2350 with layers of metal contact 2365 and 2375, which may differ significantly from those discussed above. The cross-sectional view shown depicts metal regions 2365 (e.g., between spaces of dielectric material) on the surface N + of the diffuse alloyed layer connected to metal regions 2375 (e.g., the region between spaces of dielectric material) on the surface P + of the diffuse alloyed layer. In the PV element 2350, doped regions are formed in the original N-type element. A set of structured PV elements 2350 can be folded and processed to form VMJ solar cells with improved performance.

24 is a perspective view of an exemplary embodiment of a textured multi-junction (VMJ) photoelectric cell 2405 with vertical transitions with a textured surface that is formed by stacking individual cells 2410 ₁ through 2410 ₁₀ along a direction normal to the plane of the individual cell (s) ; moreover, each individual element 2410 _k , with k = 1, 2, ... 10 consists of a PV element with a structured dielectric coating and a metal contact, as described here. While the exemplary textured PV element 2405 depicts a set of 10 separate elements, it is noted that the textured photovoltaic elements may include M individual elements, where M is a positive integer. The individual element (s) in a textured VMJ photovoltaic cell, e.g. 2410 _k , can be placed in the separate element (s) 2070 _λ , 2180 _λ or 2350, or any other separate element (s) obtained as described here. In the photovoltaic cell 2405, the textured surface 2412 is a V-shaped grooved surface; however, other grooves or indentations of various shapes can be formed, for example, grooves in the shape of U. A textured surface is formed on a plane (qrs) that is exposed or practically exposed to electromagnetic radiation as a result of processing a single block of individual elements or PV elements with structured metal contacts described in this application; see, for example, fig.20D. Incident light can be refracted in a plane 2430 having a normal vector n 2432. Such a plane 2430 is parallel to the surface (s) of the individual element (s) 2410 _k onto which structured dielectric material is applied, and may include a cross-sectional configuration grooves 2415, the plane 2430 is almost perpendicular to the direction of application of the individual elements 2410 _k . Texturing the surface of a single block of individual elements 2410 _k , which leads to a textured surface 2412, makes it possible to direct refracted light from the P + and N + diffuse doped regions without interfering with photo-generation of carriers, thereby effectively making the individual elements that make up the textured photoelectric element 2405 thinner and reducing recombination loss as described above. Moreover, an antireflection coating can be used on the textured surface 2410 to increase the absorption of incident light by the element.

Considering the exemplary systems and elements described above, exemplary methods that can be used in accordance with the disclosed subject matter of the invention can be better appreciated with reference to the flowcharts of FIGS. 25-27. In order to simplify the explanation, the methods proposed and described herein are presented and described as a sequence of steps; nevertheless, it should be understood and appreciated that the objects of the invention described and cited in the claims are not limited by the sequence of steps, since some steps can be carried out in a different order and / or simultaneously with other steps of those depicted and described here. For example, it should be understood and appreciated that the method described herein may alternatively be represented by a sequence of interrelated actions or events, such as a state diagram or interaction diagram. Moreover, not all of the steps depicted may be required to apply the exemplary method in accordance with this invention. In addition, the exemplary methods described herein can be applied together to understand one or more features or advantages.

25 is a flowchart of an exemplary method 2500 for manufacturing VMJ solar cells with reduced recombination loss of carriers in accordance with aspects disclosed herein. This example method is not limited to solar cells and can also be used to produce any or almost any photovoltaic device. One or more of the component (s) or module (s) described herein may affect this exemplary method 2500. At step 2510, a number of surfaces of the photovoltaic element (eg, PV element 1910) are structured by a dielectric coating. Structuring a PV element with a dielectric coating involves using any suitable technology to create one or more dielectric coatings, discussed above. As an example, structuring can be done using deposition and photolithography technologies. As another example, etching techniques can also be used to supplement or complement the used structuring protocols. Almost any or any dielectric material can be used to cover a number of surfaces. At 2520, a metal contact is deposited on one or more structured surfaces of the PV element. An alternative or additional implementation of step 2530 may include the deposition of an ohmic contact or conductive contact on one or more structured surfaces of the PV element. The material for the metal contact or ohmic contact can be practically any or any conductive material, for example, a low-resistance doped semiconductor or metal. In an aspect, the conductive material preferably has thermal (s) coefficient (s) that (s) substantially matches (s) thermal (s) coefficient (s) of the semiconductor material of the PV element. In another aspect, the conductive material has compound characteristics that contribute to the addition of structured and metallized PV elements. In yet another aspect, the structure (s) of the coating (s) of the dielectric material ensures (s) that the metallization of opposite surfaces leads to the formation of areas of low resistance by connecting metal areas on different surfaces (for example, 90-degree deviated strip-shaped openings in structures 2330 and 2340 lead to the formation of areas of metal contact connected along the direction of application (for example, direction z 2080)). At block 2530, a series of structured metallized cells are added to form a VMJ solar cell. It should be appreciated that such FE elements may include limited diffuse doping regions, as discussed above. At step 2540, the generated VMJ solar cell is processed to facilitate deployment of the PV device, to optimize photovoltaic efficiency, or to achieve both. Such processing may include various manufacturing steps or processes, such as a cutting process, a polishing process, a cleaning process, connecting processes and the like. Such processes can be directed, at least in part, to the opening of a particular crystalline surface to sunlight when the VMJ-formed solar cell is used in a PV device. In one example, the treatment includes a VMJ element (s) formed by cutting so as to open or practically open <100> crystalline planes to sunlight in order to establish lower degrees of surface passivation.

FIG. 26 is a flowchart of an exemplary method 2600 for producing solar cells with reduced recombination loss of carriers in accordance with aspects described herein. This exemplary method 2600 is not limited to the production of solar cells; an exemplary method 2600 can also be used to produce any or almost any photovoltaic cell. One or more of the component (s) or module (s) described herein may affect this exemplary method 2600. At step 2510, a number of surfaces of the photovoltaic element (eg, PV element 1910) are structured by a dielectric coating. Structuring a PV element with a dielectric coating involves using any suitable technology to create one or more dielectric coatings, discussed above. As an example, structuring can be done using deposition and photolithography technologies. As another example, etching techniques can also be used to supplement or complement the used structuring protocols. Almost any or any dielectric material can be used to cover a number of surfaces. At 2620, a structured dielectric coating can be used to form limited diffuse doping regions in the PV element. A structured dielectric coating can be used as a mask, which determines the degree of restriction of the doped regions. In one aspect, the limitation of the doped regions may be two-sided, with doping generally extending in one direction and bounded in two opposite directions. The limitation of the doping regions can also be almost tripartite, where doping in the PV element is limited by a number of one or more localized regions significantly smaller than the size of the PV element (see, for example, FIG. 22). As an example, the structure of a dielectric material with stripes (for example, structure 2330) when used as a doping mask can lead to diffuse doped layers that are practically limited in two directions, for example, the direction of diffusion towards the center of the plate of the nominal undoped semiconductor material and the direction normal to a step or strip of structured coverage. The limited regions of the diffuse (s) doped layer (s) reduce their volume and reduce the recombination losses of photogenerated carriers.

At 2630, an ohmic contact is deposited on one or more of the structured surfaces of the PV element. Practically any or any conductive material, for example, a low-resistance doped semiconductor or metal, can be used as a material for ohmic contact. In an aspect, the conductive material practically coincides in value of the thermal coefficient (s) with a semiconductor material, for example, Si, Ge, GaAs, InAs or another semiconductor structure of III-V groups, semiconductor structure of II-VI groups, CuGaSe, CuInSe, CuInGaSe ..., PV element and suitable for fusion. As indicated above, the structure (s) of the coating (s) of the dielectric material ensures that the deposition of ohmic contact on opposite structured surfaces leads to the formation of areas of low electrical resistance by connecting metallized areas on different surfaces (for example, strip-shaped holes deflected 90 degrees in structures 2330 and 2340 lead to the formation of areas of metal contact connected in the direction of application (for example, in the z direction 2080)).

At 2640, a set of structured metallized photovoltaic cells is added to form a solar cell. The set of photovoltaic cells that form the solar cell includes M cells, where M is a natural number determined, at least in part, by the desired operating voltage of the solar cell. In an aspect, the set of PV elements may be homogeneous or heterogeneous. In a homogeneous set, each element or a separate element of the set is based on the same source elements, while in a heterogeneous set, each element is based on different source elements. Different initial elements can be based on the same semiconductor structures, for example, Si, Ge, GaAs, InAs or other semiconductor structures of III-V groups, semiconductor structures of II-VI groups, CuGaSe, CuInSe, CuInGaSe, but differ in the type of doping or, for structures alloys, alloy concentration. In addition, such structured metallized PV elements include limited diffuse alloying regions, as discussed above. At step 2650, the solar cell is processed to facilitate deployment of the PV device, optimize photovoltaic efficiency, or to achieve both. Such processing may include various manufacturing steps or processes, such as a cutting process, a polishing process, a cleaning process, connecting processes and the like. Such processes can be directed, at least in part, to the opening of a particular crystalline surface to sunlight when the formed solar cell is used in a PV device. In one example, the treatment includes a VMJ element (s) formed by cutting so as to open or practically open (100) the crystalline planes to sunlight in order to establish lower degrees of surface passivation. It should be appreciated that the solar cell can be machined to open or practically open other crystalline surfaces, for example, (qrs) planes, such as (311).

FIG. 27 is a block diagram of an example system 2700 that enables the production of solar cells in accordance with the aspects described herein. Deposition reactor (s) 2710 makes it possible to process semiconductor-based wafers to produce PV cells or individual cells that make up solar cells, such as VMJ solar cells, as described herein. The deposition reactor (s) 2710 and module (s) therein include various pieces of equipment, software items, or a combination (s) thereof, and associated electrical and electronic networks to carry out the work. In an aspect, coating module (s) 2712 allows for surface structuring of a semiconductor wafer or substrate with a dielectric coating. The plate or substrate can be nominally unalloyed or alloyed and are the starting elements of the PV elements used for the production of solar cells. As indicated above, crosslinking can be based on the deposition of dielectric material using a suitable mask, photolithography or etching. The deposition reactor (s) 2710 also includes a doping module (s) that (s) allows (s) to incorporate dopants into the semiconductor feed elements for the PV elements. Dopants can form diffuse dopants as described above (see, for example, FIG. 19 or FIG. 23); however, doping module (s) 2714 can also (gut) provide virtually any type of doping, such as doping based on epitaxial growth, for example, delta doping. In addition, doping module (s) 2714 makes it possible to form diffuse barriers that can prevent self-doping.

As described above, the coating of the PV element with a dielectric material can be carried out before or after alloying. Doping after deposition of a structured dielectric involves a type of deposition, such as using a mask, to obtain limited or practically limited doping regions (see, for example, FIG. 22).

The metallization module (s) 2716 makes it possible to deposit metal (s) layer (s) on the PV element, which includes doping regions, unlimited or limited, and structured dielectric coating (s). Metallization can be carried out by deposition of a semiconductor material followed by alloying or a metal material. In an aspect, such materials have thermal coefficient (s) that coincide or practically coincide with thermal coefficient (s) of the PV element (s) with doped regions.

Deposition reactor (s) 2719 may (gut) include spray chamber (s), chamber (s) for epitaxial growth, chamber (s) for vapor deposition; electron beam gun (s); holder (s) of the source material; plate storage; substrate sample; furnace (s), vacuum pump (s); for example, a turbomolecular pump, a diffusion pump and the like. In addition, sedimentation reactor (s) 2710 may (gut) include computer (s) including processor (s) and memory therein, the memory devices being volatile or nonvolatile; programmable logic controller (s); specialized processor (s), such as narrowly targeted chipset (s) or the like. Reactor (s) for deposit 2710 may also include software application (s), such as operating system (s), or code sequences to influence one or more production steps, including at least , those described above. The described equipment, software and their combination contribute to or make possible at least partial functioning of the reactor (s) for deposit 2710 and module (s) in them. The 2718 bus makes it possible to exchange information, for example, information or code instructions, on the transfer of materials, on the change of processed elements, and so on, between various equipment, software, and their combination (s) in the reactor (s) for deposit 2710.

Photovoltaic (s) element (s) may be supplied to packaging platform 2730 for further processing. Communication for exchange, for example, conveyor communication or an exchange chamber and electromechanical ones leaving in them, can supply PV element (s); at least one of the links for exchange or the exchange chamber is shown as arrows 2720. The structure of module (s) 2732 can assemble a set of PV elements (s) and allows each of the PV elements to be superimposed by a high-temperature process or step in order to obtain a solar cell , for example, VMJ solar cell. The block moves to module (s) of specification 2734, which brings the solar cell to the specified specification, for example, the block is sawn to allow the individual crystalline plane of the PV cells to open in the block that forms the solar cell. Such processing can (gut) facilitate or make it possible, at least in part, test module (s) 2760, which can determine the crystallographic orientation of the PV elements or individual elements in a solar cell; such a determination can be established using x-ray spectroscopy, for example, the diffraction spectrum and the characteristic curve of the swing.

To guarantee quality or meet specifications, test module (s) 2760 may (gut) examine raw materials or processed materials at various stages of the solar cell manufacturing process. By way of example, test module (s) 2760 may (gut) examine the density of holes in the structured dielectric coating of the PV element (s) to determine whether such a density is suitable for the intended intensity of solar radiation or photon flux in a solar concentrator. In another example, the test module (s) can (gut) determine the density of defects, which can increase during thermal batch treatment of the PV element with metal layers to determine whether the material or metallization process is suitable. Finally, test module (s) 2760 can (gut) at least be used to measure minority carrier lifetimes, X-ray spectroscopy, scanning electron microscopy, tunneling electron microscopy, scanning tunneling microscopy, electron energy loss spectroscopy, or the like. The test (s) carried out by the test module (s) of tests 2760 may be carried out both at the place of production and outside. Samples of the starting elements of the processed materials or devices, for example, solar cells, can be transferred to the test module (s) through communication links 2740 and 2750.

The processing device (a) (not shown (s)) can act on the logic to control at least part of the various processes described here in connection with the operation of the 2700 system. Such processing device (a) (not shown) (s)) may (gut) include code instructions that affect control logic; code instructions, for example, software module (s) or software applications, may be stored in memory device (s) (not depicted (s)) functionally coupled to processor (s).

The foregoing includes examples of systems and methods that provide advantages of the present invention. Of course, it is impossible to describe all possible combinations of elements or methods for the purpose of describing the present invention, but one of ordinary skill in the art may understand that many other combinations and variations of the present invention described in the claims are possible. In addition, in the case where the terms “contains”, “has”, “possesses” and the like are used in the detailed description, claims, appendices and drawings, it is understood that these terms are also inclusive, as the term “includes”, when “includes” is interpreted when used as a transition word in a claim.

Claims (22)

1. A photovoltaic cell containing:
a monolithic block of a plurality of semiconductor-based photovoltaic (PV) elements, where each element of said plurality of semiconductor-based PV elements includes at least one P-type diffusion doped layer or an N-type diffuse doped layer;
a structured dielectric coating applied to at least one P-type diffusion doped layer or an N-type diffusion doped layer, the structures on said structured dielectric coating reducing the contact surface area between the metal layer and the doped layers to reduce the recombination losses of photogenerated carriers in a plurality made on the basis of PV semiconductors; and a metal layer located on the interface between the elements in a plurality of PV elements based on semiconductors. 2. The photovoltaic cell of claim 1, wherein the at least one P-type diffusion doped layer or an N-type diffusion doped layer includes one or more limited regions. 3. The photovoltaic cell of claim 2, wherein the structured dielectric coating includes at least one of the disconnected regions of the dielectric material or the connected regions of the dielectric material. 4. The photovoltaic cell according to claim 3, in which the connected region of the dielectric material includes at least one of the periodic lattice of the dielectric regions or, essentially, a periodic lattice. 5. The photovoltaic cell according to claim 3, in which the disconnected region of the dielectric material includes at least one of a set of strips oriented at a first angle relative to the crystalline direction <qrs>, or a set of strips oriented at a second angle different from the crystalline direction <qrs>, where q, r, and s are Miller indices. 6. The photovoltaic cell according to claim 5, in which the density of the bands in at least one of said sets of strips is set at least partially based on the radiation intensity at which a plurality of PV cells based on semiconductors are expected to operate. 7. The photovoltaic element according to claim 5, in which the first diffusion doped layer in the PV element is coated with the first structure of the dielectric material, and the second diffusion doped layer in the PV element is covered with the second structure of the dielectric material. 8. The photovoltaic cell of claim 7, wherein the first structure of the dielectric material is determined at least in part by recombination loss mechanisms in the first diffusion doped layer. 9. The photovoltaic cell of claim 8, wherein the second structure of the dielectric material is determined at least in part by recombination loss mechanisms in the second diffusion doped layer. 10. The photovoltaic cell of claim 1, wherein the block of the plurality of semiconductor-based photovoltaic (PV) cells is processed so as to substantially expose the particular crystalline (s) plane (s) to sunlight. 11. The photovoltaic cell according to claim 1, in which the metal layer has a coefficient of thermal expansion (s), which (s) essentially coincides (s) with the coefficient (s) of thermal expansion of the semiconductor material of the photoelectric element. 12. The photovoltaic cell according to claim 1, in which the current output during energy conversion carried out on the basis of semiconductors based on photovoltaic (PV) elements is almost the same. 13. The photovoltaic cell of claim 1, wherein each element of the plurality of PV elements based on semiconductors is formed by doping one of an N-type semiconductor precursor, a P-type semiconductor precursor, or a semiconductor precursor with intrinsic conductivity. 14. The photovoltaic cell according to claim 1, wherein the surface of the monolithic block includes a textured surface with a structure of formations in the form of recesses. 15. A method of manufacturing photovoltaic cells with reduced recombination losses of photogenerated carriers, the method comprising:
structuring a number of surfaces of the photovoltaic (PV) element using a dielectric coating to reduce the contact surface area between the ohmic region and the doped regions and to reduce the recombination losses of photogenerated carriers in said PV;
applying ohmic contact to one or more structured surfaces of the PV element;
arrangement as a package of a block of structured PV elements with ohmic contacts in order to form a multi-junction (VMJ) photoelectric element with vertical transitions and
processing the generated VMJ photovoltaic cell in order to facilitate application in a photovoltaic device, optimize photovoltaic performance, or achieve both. 16. The method according to clause 15, in which one or more surfaces of the aforementioned series of surfaces includes a diffusion doped layer, which covers an expanded region or a limited region. 17. The method according to clause 15, also containing the use of a structured dielectric coating as a mask to obtain limited areas of diffusion doping in the photovoltaic cell. 18. The method according to clause 15, in which the material for ohmic contact is a conductive material with a coefficient (s) of thermal expansion, which (s) essentially coincides with the coefficient (s) of thermal expansion of the photoelectric element. 19. The method according to clause 15, in which the structuring of the aforementioned surface of a photovoltaic (PV) element with a dielectric coating includes applying at least one of a set of strips oriented at a first angle relative to the crystalline direction <qrs> in the PV element, or a set bands oriented at a second angle different from the crystalline direction <qrs> in the PV element, where q, r, and s are Millera indices. 20. The method according to claim 19, in which the density of the bands in at least one of the sets of bands is set at least in part based on the radiation intensity at which a plurality of PV elements based on semiconductors are expected to work. 21. The method according to clause 15, in which the processing step includes cutting the generated VMJ photoelectric element, in order to essentially open the crystalline (s) plane (s) (qrs) to sunlight, where q, r and s are Millera indices. 22. The method according to clause 15, in which the block of structured PV elements with ohmic contacts, which forms the VMJ photoelectric element, is current-coordinated.

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