Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F77/00—Constructional details of devices covered by this subclass
  • H10F77/20—Electrodes
  • H10F77/206—Electrodes for devices having potential barriers
  • H10F77/211—Electrodes for devices having potential barriers for photovoltaic cells
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F10/00—Individual photovoltaic cells, e.g. solar cells
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F10/00—Individual photovoltaic cells, e.g. solar cells
  • H10F10/10—Individual photovoltaic cells, e.g. solar cells having potential barriers
  • H10F10/16—Photovoltaic cells having only PN heterojunction potential barriers
  • H10F10/167—Photovoltaic cells having only PN heterojunction potential barriers comprising Group I-III-VI materials, e.g. CdS/CuInSe2 [CIS] heterojunction photovoltaic cells
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F71/00—Manufacture or treatment of devices covered by this subclass
  • H10F71/139—Manufacture or treatment of devices covered by this subclass using temporary substrates
  • H10F71/1395—Manufacture or treatment of devices covered by this subclass using temporary substrates for thin-film devices
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F77/00—Constructional details of devices covered by this subclass
  • H10F77/10—Semiconductor bodies
  • H10F77/16—Material structures, e.g. crystalline structures, film structures or crystal plane orientations
  • H10F77/169—Thin semiconductor films on metallic or insulating substrates
  • H10F77/1694—Thin semiconductor films on metallic or insulating substrates the films including Group I-III-VI materials, e.g. CIS or CIGS
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F77/00—Constructional details of devices covered by this subclass
  • H10F77/10—Semiconductor bodies
  • H10F77/16—Material structures, e.g. crystalline structures, film structures or crystal plane orientations
  • H10F77/169—Thin semiconductor films on metallic or insulating substrates
  • H10F77/1698—Thin semiconductor films on metallic or insulating substrates the metallic or insulating substrates being flexible
  • H10F77/1699—Thin semiconductor films on metallic or insulating substrates the metallic or insulating substrates being flexible the films including Group I-III-VI materials, e.g. CIS or CIGS on metal foils or polymer foils
• • 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
  • Y02E10/541—CuInSe2 material PV cells

Definitions

• the present invention relates to a solar cell apparatus and a method of fabricating the same.
• a CIGS-base solar cell that is, p-n hetero junction device having a substrate structure including a glass substrate, a metal backside electrode layer, p-type CIGS-base light absorption layer, a buffer layer, n-type transparent electrode layer and the like is widely used.
• the material included in the substrate during high temperature process such as light absorption layer forming may be diffused into the light absorption layer, thereby lowering the efficiency of the solar cell.
• a CIGS film forming process grown at high temperatures proceeds using the glass as the growth substrate, and the sacrificial layer formed on the rigid glass substrate is removed by the electrolysis method.
• an advantage of some aspects of the invention is that the bonding layer and the flexible substrate are formed under the backside electrode layer, thereby providing the solar cell having excellent curve and improved photoelectric conversion efficiency and reliability.
• the solar cell according to the embodiment includes a backside electrode layer, a light absorption layer on the backside electrode layer, a buffer layer on the light absorption layer, a window layer on the buffer layer, and a bonding layer under the backside electrode layer.
• a method of fabricating a solar cell includes forming a sacrificial layer on a growth substrate; forming a backside electrode layer on the sacrificial layer; forming a light absorption layer on the backside electrode layer; forming a top electrode layer on the light absorption layer; forming a sheet above the top electrode layer; and removing the sacrificial layer so that a bottom surface of the backside electrode layer is exposed by performing the electrolysis on the solar cell.
• a solar cell and a method of fabricating the same having flexibility and improved photoelectric conversion efficiency and reliability is provided.
• FIG. 1 is a section view of a solar cell according to an embodiment of the present invention.
• FIGS. 2 to 7 show the method of fabricating the solar cell according to an embodiment of the present invention.
• FIG. 1 is a section view showing a solar cell according to an embodiment of the present invention.
• FIGS. 2 to 7 show the method of fabricating the solar cell according to an embodiment of the present invention.
• the solar cell according to the embodiment includes a substrate 110, a bonding layer 250 on the substrate 110, a backside electrode layer 200 on the bonding layer 250, a light absorption layer 300 on the backside electrode layer 200, a buffer layer 400 and a high-resistant buffer layer 500 on the light absorption layer 300, a window layer 600 on the high-resistant buffer layer 500, and a first protection layer 700 on the window layer 600.
• a second protection layer 800 may be formed under the substrate 110.
• the substrate 110 has a plate shape, and supports the backside electrode layer 200, the light absorption layer 300, the buffer layer 400, the high-resistant buffer layer 500 and the window layer 600.
• the substrate 110 may be a flexible substrate such as PET(polyethylene terephthalate), but is not limited thereto.
• the backside electrode layer 200 is arranged on the substrate 110.
• the backside electrode layer 200 becomes a conductive layer.
• the backside electrode layer 200 allows charges produced from the light absorption layer 300 of the solar cell to move, such that current may flow outside the solar cell.
• the backside electrode layer 200 needs to have high electricalconductivity and small specific resistance to perform above function.
• the backside electrode layer 200 should be maintained to have high temperature stability when heat-treating under the atmosphere of sulfur(S) or selenium(Se) accompanied in forming CIGS compound.
• Such a backside electrode layer 200 may be formed by any one of molybdenum (Mo), gold (Au), aluminum (Al), chromium (Cr), tungsten (W) and copper (Cu) Among them, particularly, the molybdenum (Mo) enables the characteristic required for the backside electrode layer 200 to generally satisfy as compared with other element.
• Mo molybdenum
• Au gold
• Al aluminum
• Cr chromium
• W tungsten
• Cu copper
• Mo molybdenum
• the backside electrode layer 200 may include at least two layers. In this case, each layer may be formed by same metals or metals different from each other.
• the portion of a sacrificial layer 105(refer to FIG. 3) may remain under the backside electrode layer 200.
• some of metallic crystals of the Cu may be present under the backside electrode layer 200.
• a second protection layer 800 may be formed under the substrate 110.
• the second protection layer 800 acts a role to protect the solar cell against water and air of the outside.
• the second protection layer 800 may be formed by a polymer layer.
• the second protection layer 800 for example, including material such as PVF, polyester, acrylic, EVA may be formed.
• the backside electrode layer 200 may be directly connected to the second protection layer 800 without forming the substrate 110.
• the light absorption layer 300 may be formed on the backside electrode layer 200.
• the light absorption layer 300 includes p-type semiconductor compound.
• the light absorption layer 300 includes group I-III-VI?base compound.
• the light absorption layer 300 may has Cu-In-Ga-Se-base(Cu(In,Ga)Se 2 ;CIGS-base) or Cu-Ga-Se-base crystal structure.
• the buffer layer 400 and the high-resistant buffer layer 500 may be formed on the light absorption layer 300.
• the solar cell having CIGS compound as the light absorption layer 300 forms p-n junction between a p-type semiconductor, that is, a CIGS compound thin film and a n-type semiconductor, that is, a window layer 600 thin film.
• the material forming the buffer layer 400 is CdS, ZnS and the like, the CdS is a relatively good in terms of power generation efficiency of the solar cell.
• the high-resistant buffer layer 500 includes zinc oxide(i-ZnO) not doped with impurity.
• the energy bandgap of the high-resistant buffer layer 500 is about 3.1eV to 3.3eV.
• the window 600 is formed on the high-resistant buffer layer 500.
• the window layer 600 is transparent and a conductive layer. Further, resistance of the window layer 600 is higher than that of the backside electrode layer 200.
• the window layer 600 includes oxide.
• the window layer 600 may include zinc oxide, indium tin oxide; ITO or indium zinc oxide; IZO and the like.
• the oxide may include conductive impurities such as aluminum(Al), alumina(Al 2 O 3 ), magnesium(Mg) or gallium(Ga).
• the window layer 600 may include Al doped zinc oxide; AZO, B doped zinc oxide; BZO or Ga doped zinc oxide; GZO.
• the first protection layer 700 and the second protection layer 800 may be formed on the top and bottom surface of the solar cell.
• FIGS. 2 to 7 are sectional views showing the method of fabricating the solar cell according to an embodiment of the present invention.
• the description regarding the present fabricating method refers to the descrition regarding the solar cell described previously.
• the sacrificial layer 105 grows on a growth substrate 100.
• the growth substrate 100 may be an insulator.
• the growth substrate 100 may be a glass substrate.
• the growth substrate 100 may be a soda lime glass substrate.
• the growth substrate 100 becomes a soda lime glass
• Na contained in the soda lime glass may be diffused into the light absorption layer 300 formed by the CIGS during the fabricating process of the solar cell, which allows charge concentration of the light absorption layer 300 to increase. That may become a factor that may increase photoelectric conversion efficiency of the solar cell.
• a ceramic substrate such as alumina, stainless steel, flexible polymer and the like are used as the material of the growth substrate 100.
• the growth substrate 100 may be transparent and rigid or flexible.
• the sacrificial layer 105 may include a metal.
• the sacrificial layer 105 may include elements such as Cu, Ag, Au and the like.
• the backside electrode layer 200 is formed on the sacrificial layer 105.
• the backside electrode layer 200 may be formed by any one of molybdenum (Mo), gold (Au), aluminum (Al), chromium (Cr), tungsten (W) and copper (Cu).
• Mo molybdenum
• Au gold
• Al aluminum
• Cr chromium
• W tungsten
• Cu copper
• the backside electrode layer 200 may include at least two layers. In this case, each layer may be formed by same metals or metals different from each other.
• the backside electrode layer 200 may be formed by PVD(Physical Vapor Deposition) or plating.
• the light absorption layer 300 is formed on the backside electrode layer 200.
• the light absorption layer 300 is widely fabricated by the method forming the light absorption layer 300 of Cu-In-Ga-Se-base(Cu(In,Ga)Se 2 ;CIGS-base) while simultaneously or separately evaporating, for example, Cu, In, Ga and Se, and the method using a selenization process after forming a metal precursor film.
• the metal precursor film is formed on the backside electrode layer 200 by a sputtering process using Cu target, In target and Ga target.
• the metal precursor film becomes the light absorption layer 300 of Cu-In-Ga-Se-base(Cu(In,Ga)Se 2 ;CIGS-base) by the selenization process.
• the sputtering process using the Cu target, the In target and the Ga target is simultaneously performed with the selenization process.
• CIS-base or CIG-base light absorption layer 300 may be formed by the sputtering process using only the Cu target and the In target or the Cu target and the Ga target, and the selenization process.
• cadmium sulfide is deposited by the sputtering process and a chemical bath depositon(CBD) method and the like to form the buffer layer 400.
• the zinc oxide is deposited on the buffer layer 400 by the sputtering process to form the high-resistant buffer layer 500.
• the buffer layer 400 and the high-resistant buffer layer 500 are deposited to a small thickness.
• a thickness of the buffer layer 400 and the high-resistant buffer layer 500 is about 1nm to 100nm.
• the window 600 is formed on the high-resistant buffer layer 500. That is, the window layer 600 is formed by depositing transparent conductive material on the high-resistant buffer layer 500. In detail, the window layer 600 may be formed by depositing the zinc oxide doped with the aluminum, but is not limited thereto.
• the first protection layer 700 is formed on the window 600.
• the first protection layer 700 may be formed by a deposition method.
• the first protection layer 700 includes EVA sheets to prevent damage for the panel of the solar cell when performing electrolys is.
• the aqueous solution may be formed depending on the material included to the sacrificial layer 105 in the embodiment of the present invention.
• the aqueous solution may use copper sulfate (Cu 2 SO 4 ) contained with the copper (Cu).
• an anode (+) thereof is connected to the backside electrode layer 200 and a cathode is connected to a separate metal plate 107 spaced apart from the solar cell, thereby performing the electrolysis.
• the sacrificial layer 105 contained with the metal is difficult to perform the electrolysis, and therefore, it is preferable to connect the anode to the backside electrode layer 200.
• the sacrificial layer 105 is etched by the electrolysis, such that the sacrificial layer 105 and the growth substrate 100 are separated from the backside electrode layer 200.
• the sacrificial layer 105 is etched by the electrolysis, but some of sacrificial layer 105 as the crystal form may remain in the backside electrode layer 200.
• FIG. 6 is a sectional view showing the solar cell after removing the sacrificial layer 105 by the electrolysis.
• the backside electrode layer 200 is exposed by the electrolysis process. Some of he material included in the sacrificial layer 105 may remain, for example, as the crystal form under the backside electrode layer 200.
• a bonding agent is applied below the backside electrode layer 200 to form the bonding layer 250.
• the bonding layer 250 allows adhesion of the backside electrode layer 200 and the substrate 110 to improve.
• the bonding layer 250 may be formed using polymeric material such as epoxy or ceramic series bond.
• the substrate 110 may be a flexible substrate such as PET(polyethylene terephthalate), but is not limited thereto. Further, the substrate 110 may not be formed.
• the second protection layer 800 may be formed under the substrate 110.
• the second protection layer 800 may protect the solar cell from the outside, and may be formed by the same or different material as the first protection layer 700.
• the first and second protection layer 800 may be composed of Siloxane, PDAS(poly dialkyl siloxane) or film types of EVA(Ethylene Vinyl Acetate).
• the backside electrode layer 200 may contact the second protection layer 800.
• a CIGS film forming process grown at high temperatures proceeds using the glass as the growth substrate, and the sacrificial layer 105 formed on the rigid glass substrate is removed by the electrolysis method.
• the bonding layer 250 and the flexible substrate 110 are formed under the backside electrode layer 200, thereby providing the solar cell having excellent curve and improved photoelectric conversion efficiency and reliability.

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• 2011
  • 2011-01-27 KR KR1020110008481A patent/KR101241708B1/ko not_active Expired - Fee Related
  • 2011-11-29 EP EP11856848.4A patent/EP2668668A2/de not_active Withdrawn
  • 2011-11-29 CN CN201180066301.9A patent/CN103339741B/zh not_active Expired - Fee Related
  • 2011-11-29 WO PCT/KR2011/009147 patent/WO2012102476A2/en not_active Ceased

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