Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
  • H01L31/042—PV modules or arrays of single PV cells
  • H01L31/0445—PV modules or arrays of single PV cells including thin film solar cells, e.g. single thin film a-Si, CIS or CdTe solar cells
  • H01L31/046—PV modules composed of a plurality of thin film solar cells deposited on the same substrate
  • H01L31/0468—PV modules composed of a plurality of thin film solar cells deposited on the same substrate comprising specific means for obtaining partial light transmission through the module, e.g. partially transparent thin film solar modules for windows
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L31/02—Details
  • H01L31/0224—Electrodes
  • H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
  • H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L31/02—Details
  • H01L31/0224—Electrodes
  • H01L31/022466—Electrodes made of transparent conductive layers, e.g. TCO, ITO layers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
  • H01L31/042—PV modules or arrays of single PV cells
  • H01L31/0445—PV modules or arrays of single PV cells including thin film solar cells, e.g. single thin film a-Si, CIS or CdTe solar cells
  • H01L31/046—PV modules composed of a plurality of thin film solar cells deposited on the same substrate
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
  • H01L31/042—PV modules or arrays of single PV cells
  • H01L31/0445—PV modules or arrays of single PV cells including thin film solar cells, e.g. single thin film a-Si, CIS or CdTe solar cells
  • H01L31/046—PV modules composed of a plurality of thin film solar cells deposited on the same substrate
  • H01L31/0463—PV modules composed of a plurality of thin film solar cells deposited on the same substrate characterised by special patterning methods to connect the PV cells in a module, e.g. laser cutting of the conductive or active layers
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
  • H02S20/00—Supporting structures for PV modules
  • H02S20/20—Supporting structures directly fixed to an immovable object
  • H02S20/22—Supporting structures directly fixed to an immovable object specially adapted for buildings
  • H02S20/23—Supporting structures directly fixed to an immovable object specially adapted for buildings specially adapted for roof structures
  • H02S20/24—Supporting structures directly fixed to an immovable object specially adapted for buildings specially adapted for roof structures specially adapted for flat roofs
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
  • Y02B10/00—Integration of renewable energy sources in buildings
  • Y02B10/10—Photovoltaic [PV]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/50—Photovoltaic [PV] energy

Definitions

• the present invention relates to thin-film photovoltaic solar energy converters and can be applied to manufacturing of solar cells and panels with partial translucency.
• Solar energy is on the rise throughout the world, being environmentally friendly and using an inherently renewable energy source - the solar radiation.
• the greatest contribution to solar energy is made by semiconductor photovoltaic solar energy converters - solar cells, as well as modules and panels built them.
• BIPV Building Integrated Photo voltaics
• See-through solar cells are integrated in such structural units as windows, stained glass glazing, transparent roofs, and other structures that require transparency for reasons of aesthetics or functionality.
• One of the most important requirements imposed by construction industry on such see-through solar cells is low cost per watt of installed power, which remains unacceptably high owing to certain aspects of the processes that are used in order to form see-through solar cells.
• CIGS is a group of semiconductor compounds of chalcogen, copper, indium and gallium, - Cu(In,Ga)(S,Se) 2 with the structure of chalcopyrite.
• CIGS solar cells As compared to the more commercialized silicon cells, their wider use is held back by high production costs.
• Developing processes for manufacturing CIGS solar cells, increasing productivity, reducing consumption of such relatively expensive materials as indium and gallium, and thus reducing production costs, are the main problems that need to be solved in order to proceed with extensive use of see-through thin-film CIGS modules.
• the selection of the method for forming the solar module photoactive layer has to be efficient, and produce as little waste and be as inexpensive as possible.
• a see-through thin film solar module comprises a transparent substrate, an opaque metal electrode layer, a photovoltaic conversion layer, and a transparent conductive layer of the second electrode. Partial light transmission through the solar module is provided through alternation of areas involved in photovoltaic conversion of light that have high light absorption (the photoactive area), areas with high light transmission (the transparent area), and which are formed in the course of the solar module manufacturing process.
• the level of transparency can be quantitatively expressed as a ratio of the total surface area of transparent areas to the sum total of surface areas of photoactive and transparent areas.
• transparent areas are formed by removing a portion of a continuous active area by laser.
• the US patent No. US 8344245 discloses a thin-film solar cell module of see- through type which consists of solar cells electrically connected in series, each of which, in their turn, comprise a first electrode on an opaque substrate, a second electrode, and a photoactive layer between them.
• Light transmission is achieved by forming between solar cells of the module pass-through holes serving as windows in the layer of the first metal electrode, revealing the transparent substrate when the subsequent layers are removed, thus increasing the permeability to light.
• Used as the photoactive layer can be, among others, compounds of the CIGS group deposited on the entire surface of the substrate by magnetron sputtering.
• the advantages of this method are its compatibility with the existing manufacturing processes and the ability to adjust the degree of light transmission by changing the geometry of solar cells, and the sizes and the numbers of pass-through holes between them.
• the disadvantages of this method are a reduced mechanical strength of the module caused by the fact that a plurality of pass-through holes are formed all over its surface, and, therefore, a limit is imposed on the maximum level of light transmission of the solar module, as well as the excessive use of expensive photoactive layer materials that are applied to those areas of the surface that are to be removed during the final stage of the solar module manufacturing in order to provide a path for transmission of light.
• Patent application No. US 20110265843 discloses a see-through solar array module and a method for its manufacturing, which consists in forming out of a continuous layer of a metal electrode applied to a transparent substrate units of metal electrode in the shape of a 2D-array by removing a part of the continuous layer of metal electrode in two directions.
• deposited on the plurality of metal electrode units is a continuous photoelectric transducing layer and a continuous buffer layer out of which a 2D-array is formed in such a manner that in one direction adjacent elements are separated down to the substrate, thus providing the module transparency, and in the other direction down to the metal electrode, thus providing, after application of a transparent conductive layer, a series electrical connection of elements in the solar module.
• Deposition of the photoelectric transducing layer for which CIGS is used is achieved through co-evaporation in vacuum or magnetron sputtering, or thermal evaporation, accompanied by high-temperature selenization.
• the continuous metal electrode layer is divided into units of metal electrode using laser, while the elements of the 2D array of the photoelectric transducing layer and buffer layer are divided by a mechanical process, which prevents re-deposition of metal particles on the module surface and thermal exposure of the edges of elements of the photoelectric transducing layer 2D array.
• a drawback of the method is excessive consumption of highly expensive components (indium and gallium), of the photoactive CIGS layer, a part of which is removed when the photoactive layer 2D-array is formed.
• highly expensive components indium and gallium
• the highest efficiency of photoelectric conversion can be achieved by CIGS when it is deposited through co-evaporation process, but it is difficult to scale-up this deposition method to larger modules, and it takes a long time to build each module, while the required vacuum equipment is expensive.
• This manufacturing method includes forming an array of longitudinal metal electrodes on a transparent substrate by disposing a first mask above the transparent substrate when the metal electrode material is deposited, forming a photoactive layer on each longitudinal metal electrode by means of disposing a second mask above the transparent substrate when the photoactive layer is deposited, removing a part of each photoactive layer in the longitudinal direction to provide access to each longitudinal metal electrode, forming a transparent electrode layer on each photoactive layer and longitudinal metal electrode, removing a part of each transparent electrode layer and part of each photoactive layer down to each longitudinal metal electrode, thus forming a plurality of solar cells electrically connected in series in the direction that is different from the longitudinal direction of metal electrodes.
• masks make it possible to form a plurality of metal electrodes and a photoactive layer on them without using a mechanical or laser material removal technique, thus simplifying the manufacturing process, avoiding creation of module defects caused by re-deposition of materials that are being removed and thermal exposure of edges of photoactive layers, thereby increasing the yield of useful products.
• the method allows wide-ranging adjustments in the size of transparent and active areas, and thus in the degree of light transmission of the solar module.
• the use of the mask does not reduce the waste of raw materials. This method still has the disadvantage of excessive consumption of material for the photoactive CIGS layer, which remains on the surface of the mask and cannot be recycled. Furthermore, using mask introduces constraints on forming metal electrodes in various geometric shapes, for example, a hollow quadrangle, at the same time limiting the ability to vary the degree of transparency and use it to achieve aesthetic qualities of the solar module.
• a photoactive layer is formed using vacuum methods of physical vapor deposition (PVD), such as thermal evaporation and magnetron sputtering, which provide the highest photoelectrical conversion efficiency of the layers formed in solar cells.
• PVD physical vapor deposition
• thermal evaporation and magnetron sputtering which provide the highest photoelectrical conversion efficiency of the layers formed in solar cells.
• Electrochemical deposition (ECD) of thin films of the photoactive layer disclosed in patent application No. US 20120003786, patents No. US 7297868, US 9263610, and US 9041141 is of great interest owing to its relatively low cost of production and ability to deposit on substrates with large surface area, including roll-fed substrates.
• One special aspect of this process is that deposition can only be performed on electrically conductive surfaces of electrodes.
• CN 101944556 propose methods of photoactive layer deposition using ink or paste containing photoactive layer precursors, that is applied by a process of printing: inkjet printing, screen printing, flexography, gravure printing, or any other technique for applying a coat of liquid: spin-coating, slot-die coating, dipping, doctor- blading, roller-coating.
• Printing equipment is significantly less expensive as compared with PVD equipment, which has a positive effect on the cost of the product.
• the main objective of the proposed invention is to develop a method for manufacturing see-through thin-film CIGS solar module, which aims to achieve technological and economic benefits, when integrated on a large scale into building structures, through reducing the cost of production, with, among other things, an increase in the solar module degree of transparency, by means of increasing production output, and zero-waste use of expensive raw materials of indium and gallium in the photoactive layer.
• the photoactive layer is formed by electrochemical deposition or by printing precursors of the CIGS photoactive layer followed by thermal treatment, with the precursors being deposited directly on the surface of each metal electrode, leaving out other areas, as well as owing to the fact that:
• the layer of metal electrodes is formed by vacuum deposition on a transparent substrate with subsequent removal of parts of the layer by mechanical, laser or photolithographic means to form an array of alternately arranged metal electrodes separated by areas of the transparent substrate;
• the array of the metal electrodes may consist of striped metal electrodes or metal electrodes of other flat geometric shapes, their combinations, or patterns;
• the buffer layer is deposited by chemical bath deposition processes
• - parts of the buffer layer on some areas of the transparent substrate can be removed mechanically, by laser, or by photolithography process;
• - precursors of the photoactive layer are elemental, binary, ternary or intermetallic chemical compounds in the form of bulk materials or nanoparticles, each of which contains one or several components of CIGS: copper, indium, gallium, sulfur and selenium;
• various types of printing can be used, which involve the use of conductive inks or pastes based on CIGS precursors: inkjet printing, screen printing, gravure printing, flexography;
• - CIGS precursors are applied in one or several stages, with ratios of precursor concentrations and application modes that may differ from stage to stage;
• the photoactive layer is formed by high-temperature annealing of the photoactive layer precursors in inert or reactive media, for example, in the presence of gaseous sulfur, selenium, hydrogen sulphide, hydrogen selenide or their mixture;
• a copper seed layer can be pre-deposited on the metal electrode layer using the method of physical vapor deposition
• the proposed method for manufacturing of the solar module allows varying in a wide range its light transmittance, the degree of which is quantified as the ratio of the total area of transparent parts on the transparent substrate to the total area of the solar module, taking into account the actual transparency value for the transparent areas in the visible-light spectrum, which can reach up to 85%.
• the proposed invention allows making the physical dimensions of the active areas of the module so small that module elements will not be discernible by human eye even at close quarters, and whenever a need arises to form highly visible relatively large active areas, they can easily be given aesthetic shapes by manufacturing the module elements in the shape of some pattern.
• the problem of saving photoactive layer materials in prior art methods for solar module manufacturing is essentially unsolvable, since they involve such methods of the photoactive layer deposition as evaporation and sputtering - the direction diagram of the flow of matter determined by the equipment that is used, covers a wide spatial angle, which includes not only the solar module substrate, but also other internal surfaces of the vacuum equipment, including the mask, if any.
• Increasing the module light transmission degree in prior art is achieved through removal of areas of the photoactive layer resulting in a proportional decrease in utilization of raw materials. The excessive consumption of raw materials accordingly results in an increased unit cost of the installed power.
• the proposed invention in comparison with the prior art, reduces production cost of see-through thin-film solar modules when it switches to less expensive methods of depositing the photoactive layer materials and saves the expensive raw materials. This result is of special importance to large-scale integration of solar modules into construction materials and parts of buildings.
• Depositing precursors of the photoactive layer by non-vacuum liquid phase methods that are easily scalable on industrial scale (ECD or printing) exclusively on preformed metal electrodes without using masks and removing excess material, is the feature of the invention, which distinguishes it from prior art, and allows simplifying the manufacturing process, reducing the cost of production of see-through thin-film solar modules. It is obvious that the achieved technical and economic effect becomes a game changer for large-scale production of see-through thin- film solar modules of large surface area with a high light transmittance degree of more than 30%, designed for use in glass facades, transparent fences, transparent roofs, etc.
• Metal electrodes can be built in various geometric shapes and sizes, which makes it possible to vary the degree of transparency, at which the module elements are indiscernible to the human eye even at close quarters, and if they are discernible, to form the metal electrodes in the shape of a pattern, thus improving their aesthetic qualities.
• FIG. 1 is an overall view of a see-through solar module consisting of several solar cells electrically connected in series.
• FIG. 2 illustrates a variation of a plain view of a transparent substrate containing an array of E-shaped metal electrodes.
• FIG. 3 illustrates a variation of a plain view of a transparent substrate containing an array of comb-shaped metal electrodes.
• FIG. 4 illustrates a variation of a plain view of a transparent substrate with a two- dimensional array of arbitrarily shaped metal electrodes.
• FIG. 5 is a graph of manufacturing cost per one solar module with the surface area of 1 m 2 with 15% efficiency of the active area vs. the transparency of the solar module as compared with the prior art.
• the solar module is built on transparent substrate 1, formed on which is a plurality of metal electrodes 2, that are separated by areas 3 of exposed substrate, Fig. 1.
• Metal electrodes 2 are formed by applying a continuous layer of metal electrodes with subsequent mechanical, laser or photolithographic removal of layer 2 in order to form areas 3 of exposed transparent substrate 1, or by selectively applying a layer of metal electrodes on predetermined areas on the surface of the transparent substrate 1. Selectively, only on the surface of metal electrodes 2, precursors of the photoactive layer are applied and subjected to thermal processing in an inert or chemically reactive media forming the photoactive layer 4.
• Applied to the entire surface of the transparent substrate 1 is a buffer layer 5.
• each metal electrode 2 using a mechanical, laser, or photolithographic method, a portion of the buffer layer 5 and photoactive layer 4 is removed to form areas 6 of cell-to-cell connections oriented along the edge of each metal electrode 2 and providing access to metal electrodes 2 to subsequently form an electric contact.
• a transparent electrode layer 7 Applied to the entire formed surface of the transparent substrate 1 is a transparent electrode layer 7.
• parts of transparent electrode layer 7, buffer layer 5 and photoactive layer 4 are removed to form dividing areas 8, arranged in parallel to the longitudinal side of metal electrodes 2 near areas 6 of the cell-to-cell connection, providing the separation of the transparent electrode layer 7 into electrodes of individual solar cells 9.
• multiple, at least two, solar elements 9, electrically connected in series form a thin-film solar module.
• the areas 3 of exposed transparent substrate provide partial light transmission of the solar module, with the degree of light transmission of the said solar module being determined by a ratio of the total surface area of exposed transparent substrate 3 to the total surface area of the entire solar module, as well as by the degree of transparency of the materials of the transparent electrode layer 7, the buffer layer 5, and the transparent substrate 1.
• the transparent substrate 1 is usually made of soda-lime glass of arbitrary shape and size; however it can be made of other inorganic or organic materials with high degree of transparency in the visible part of the spectrum and thermal stability up to 400 - 500 °C.
• Used for the material of the metal electrodes 2 is, as a rule, molybdenum.
• the metal electrodes 2 can be strip- shaped and form a one-dimensional array of the metal electrodes 2, separated from each other in the lateral direction by the areas 3 of exposed transparent substrate, Fig. 2, 3, with each area 10 of the solar module under construction containing only one metal electrode 2 and only one area 11 for forming cell-to-cell connection, which includes one area 6 of the cell-to-cell connection and one dividing area 8.
• metal electrodes 2 can have an arbitrary geometric shape and form a two-dimensional array of metal electrodes 2, separated each from each other on all sides by areas 3 of exposed transparent substrate, Fig. 4, with each area 10 of the cell under construction containing several, at least two, metal electrodes 2 and one area 11 for forming cell-to-cell connection running through all the said metal electrodes 2 and areas 3 of exposed transparent substrate arranged inside the said area 10 of the cell of the solar module that is being manufactured.
• the number of the areas 10 to be formed in the cell of the solar module that is being manufactured is chosen arbitrarily based on the required rated output voltage of the module, which is represented by but not limited to the following list: 12 V, 24 V, 48 V etc.
• the longitudinal dimension of the striped metal electrode 2 is limited by the corresponding longitudinal dimension of the transparent substrate 1.
• the longitudinal dimension of an arbitrarily shaped metal electrode 2 within a two-dimensional array of metal electrodes 2 is limited by the corresponding outline dimension of the transparent substrate 1 divided by the number of the metal electrodes 2 in the corresponding spatial dimension of the said array.
• the transverse outline dimensions of a metal electrode 2 is limited by the corresponding outline dimension of the transparent substrate 1 divided by the number of the areas 10 of the cells in the solar module that is being manufactured. Characteristic width of lines-elements of metal electrode 2, distance between adjacent lines-elements of one metal electrode 2, as well as the distance between adjacent metal electrodes 2 independently from each other may be in the range from tens of micrometers to several millimeters.
• the characteristic width of lines-elements of a metal electrode 2 that is less than 50 microns provides the optical effect of uniform semi-transparency of the solar module that is being manufactured when viewed by naked eye even at close quarters.
• the light transmittance degree can vary in the range from 15 to 80%.
• the photoactive layer 4 Used as the photoactive layer 4 is semiconducting CIGS (CuInS 2 , CuInSe 2 , Cu(In,Ga)S 2 , Cu(In,Ga)Se 2 , and Cu(In,Ga)(S,Se) 2 ).
• the photoactive layer 4 can be characterized by variable composition in terms of the ratio of indium to gallium In:Ga and/or sulphur to selenium S:Se, as well as by nonstoichiometric content of copper and chalcogen.
• the photoactive layer 4 is formed in two steps: application of the photoactive layer precursors and their thermal processing.
• the photoactive layer precursors are elemental, binary, ternary chemical compounds or intermetalides. Furthermore, each precursors can be in form of a bulk material or in the form of nanoparticles 1 to 100 nanometers in size.
• Each precursor of the CIGS-based photoactive layer contains one or several chemical elements, which are components of CIGS: copper, indium, gallium, sulfur and selenium.
• CuIn(S,Se) 2 chalcopyrite at least one precursor containing copper and at least one precursor containing indium are required.
• CuGa(S,Se) 2 chalcopyrite at least one precursor containing copper and at least one precursor containing gallium are required.
• Cu(In,Ga)(S,Se) 2 chalcopyrite at least one precursor containing copper, at least one precursor containing indium, and at least one precursor containing gallium are required. Applying precursors containing sulfur and selenium is optional.
• the said precursors can be represented by chemical compounds in the form A, AB, A 2 B, A 2 B 3 , AB 3 , AA', AA'B 2 , C, where A is an atom of copper, indium or gallium metal, A' is an atom of copper, indium or gallium metal, that is different from the atom of metal A, B is an atom of a chemical element selected from among the following elements: oxygen O, nitrogen N, sulphur S, selenium Se, chlorine Cl, C is an atom of sulphur S or selenium Se.
• the method for applying the photoactive layer precursors is high-resolution inkjet printing, with inks being liquids containing one or more precursors of the photoactive layer.
• inks being liquids containing one or more precursors of the photoactive layer.
• printing can be repeated.
• the repeated printing is performed after the previously printed ink has dried. Ink compositions and printing conditions may differ from when the printing is repeated.
• the photoactive layer precursors are applied by means of electrochemical deposition using a three-electrode electrochemical cell.
• the surface of metal electrodes 2 is covered with a copper seed layer 10 - 500 nanometers thick deposited by physical vapor deposition technique, not shown in the drawing.
• all metal electrodes 2 covered with the copper seed layer are shorted mechanically or by temporary bridges, formed during the step when the array of metal electrodes 2 is formed, and are subsequently removed (not shown in the drawing), and are connected to one of the poles of the power supply.
• the role of the auxiliary electrode and the reference electrode of the electrochemical cell is usually played by a platinum wire grid or platinum foil, and a saturated calomel, silver chloride or standard hydrogen electrode, respectively.
• Used as the electrolyte is a liquid solution of the photoactive layer precursors.
• the temperature of the electrolyte may range from 10 to 80°C.
• the photoactive layer precursors are applied one at a time or simultaneously in potentiostatic mode, with conditions under which the deposition occurs (the applied potential, electrolyte composition, the electrolyte temperature) being able to vary.
• the deposited precursors of the photoactive layer are thermally treated in inert atmosphere, or in the presence of sulphur and/or selenium vapors at temperatures of 400 - 650 °C, to support CIGS crystallization.
• the buffer layer 5 is a layer of metal chalcogenide CdS, ZnS, Zn(0,S), In 2 S 3 , or other, having semiconducting properties and electronic type of conductivity covered by a film of undoped ZnO.
• the transparent electrode layer 7 is usually made of transparent metal oxide such as AZO, ITO, FTO, etc.
• the areas 6 of the cell-to-cell connections and dividing areas 8, that have the width of 5 - 50 microns are made mechanically, by laser micromachining, or by photolithography process.
• the distance between areas 6 of the cell-to-cell connections and dividing areas 8, which correspond to one solar cell 10, may lie in the range of 10 - 100 microns.
• the distance between the area 6 of cell-to-cell connection and the nearest edge of the corresponding metal electrode 2 can be 10 to 100 microns.
• Using the smallest values in the above ranges is necessary to minimize efficiency losses caused by a reduction in the total area of the photoactive layer 4, which takes part in the photoelectric conversion of solar light and the transport of the generated electric charge carriers.
• additional layers can be applied to its surface for various purposes, for example, metal current-collecting electrodes, anti-reflecting coatings, transparent adhesives, organic and inorganic barrier layers etc.
• an area of 80x79.2 mm equidistant from the edges of the substrate has a continuous molybdenum layer with the thickness of 0.5 - 1.5 microns deposited on it by magnetron sputtering, and after that a continuous copper seed layer with the thickness of 100 - 400 nm is deposited on it by magnetron sputtering.
• 24 equidistant stripes of metal electrodes of 1 mm in width are formed. The distance between two adjacent stripes of metal electrodes is 2.4 mm. The substrate is then washed.
• an electrolyte containing CuCl 2 , InCl 3 , GaCl 3 , and H 2 Se0 3 is prepared. Acidity of the electrolyte is adjusted to the pH value of 1.4 - 2.7 by adding sulfuric acid and ammonium hydroxide. While being continuously stirred, the electrolyte has its temperature brought up to the required temperature of 10 - 80 °C, which is then maintained constant throughout the entire deposition process.
• the electrochemical deposition process continues until the thickness of the deposited CIGS precursors reaches 0.7 - 2.0 microns. Since electrochemical deposition takes place only on conductive elements under cathode potential, the CIGS precursors end up deposited exclusively on the surface of metal electrodes.
• the substrate is thermally treated in a vacuum chamber with a selenium vapors at a temperature of 450 - 600 °C for 30 - 180 minutes until complete CIGS selenization and crystallization are achieved.
• a selenium vapors at a temperature of 450 - 600 °C for 30 - 180 minutes until complete CIGS selenization and crystallization are achieved.
• CdS cadmium sulfide
• the entire surface of the substrate is coated by magnetron sputtering with a 100 - 300 micron transparent electrode layer of aluminum-doped zinc oxide ZnO:Al.
• laser micromachining is used to form separating areas 30 - 100 micron wide, 100 mm long and with the depth equal to the sum of the transparent electrode layer, buffer layer, and the CIGS photoactive layer thicknesses.
• solar cells have been formed on the substrate, that are electrically connected in series constituting a solar module.
• metal current collecting contacts of the module are formed by thermal evaporation through mask.
• the degree of the solar module transparency in the visible light is 56%.
• a 5 - 25 nm thick layer of sodium fluoride NaF is deposited using thermal evaporation through a mask, and then, through the same mask, without moving it with respect to the transparent substrate, a 0.5 - 1.5 microns thick molybdenum layer is deposited by thermal evaporation, to form 72 electrodes in the shape of stripes 90 mm long and 0.84 mm wide, at a distance of 0.42 mm from each other.
• an ink is prepared that is a mixture of CIGS precursors in the form of a dispersion of InSe, CuSe, and GaSe nanoparticles.
• Inkjet printing is performed with the use of a high-resolution inkjet printer in a controlled atmosphere at a controlled temperature. The ink is applied only on the surface of metal electrodes. After the application the substrate is heated and held at 100 - 250 °C for 5 - 15 minutes, after which the printing process is repeated until the dry layer of CIGS precursors reaches the thickness of 0.7 - 2 microns.
• the substrate is annealed in vacuum at 350 - 450 °C for 30 - 180 minutes until the precursor solvent is completely removed and the CIGS christallizes.
• the entire working area of the substrate is covered with a 30 - 70 nm buffer layer of cadmium sulphide CdS using chemical deposition, and then a 10 - 50 nm layer of undoped zinc oxide ZnO is deposited using magnetron sputtering.
• the entire working area of the substrate is coated with a 100 - 300 micron transparent electrode layer of aluminum-doped zinc oxide ZnO:Al using magnetron sputtering.
• a part of the layer of the transparent frontal electrode, buffer layer and the CIGS photoactive layer using laser micromachining, along each area of the cell-to-cell connection at the distance of 10 - 30 microns from it, separating areas are formed that are 10— 30 microns wide and have a depth that is equal to the sum of thicknesses of transparent electrode layer, buffer layer and the photoactive layer, and that run through the entire working area of the substrate.
• a solar module which consists of 72 solar cells electrically connected in series. Along the first and the last solar cells of the module from the side of the substrate edge the two current collecting contacts of the module are formed using thermal evaporation through a mask. After that the module is laminated using a polymer coating. Taking the transparency of the areas containing a metal electrode to be equal to zero, while the transparency of exposed areas on the substrate to be 75%, when the total surface area of the transparent substrate is 2683.8 mm 2 , and the work area is 8127 mm 2 , the transparency of such solar module will be 24.8%.
• the proposed method of manufacturing see-through thin-film solar module reduces production costs, because, in contrast to the prior art, it uses relatively inexpensive, frugal, and easy-scalable methods of liquid phase deposition of the photoactive layer that do not require vacuum and allow to apply the photoactive layer only on the surface of metal electrodes, thus avoiding the need to remove the layer from other areas on the substrate to obtain the required degree of transparency, as opposed to the prior art.
• This saves expensive raw materials.
• This operational benefit has a significant effect on reducing the costs of manufacturing this type of solar modules, with the cost per watt of installed power being almost independent of the degree of light transmittance.
• the production cost for one solar module with the surface area of 1 m 2 and the active area efficiency of 15% vs. the degree of transparency of the solar module built according to the proposed invention in comparison with the prior art is plotted in FIG. 5. It can be seen from the plot that in the prior art an increase in transparency of the solar module does not have any effect on its production cost, and, accordingly, the cost per watt of installed power goes up, while in the proposed method the cost of per watt of installed power remains the same, with the module production cost going down. The savings in this case can be higher than 34%.
• the claimed invention is a simple, inexpensive method for manufacturing see-through thin- film solar modules, which is easy to adapt to manufacture, provides savings of the photoactive layer raw materials, reduces production costs, improves manufacturing productivity owing to the high speed of depositing the photoactive layer, primarily on large surface areas, reduces the cost of the see-through solar module, and offers the capability to adjust its degree of light transmittance in a broad range.

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• 2018
  • 2018-05-29 RU RU2018119776A patent/RU2682836C1/ru active
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