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WO2013046968A1 - Substrat de cellule solaire et son procédé de fabrication, cellule solaire à couches minces et son procédé de fabrication, procédé de fabrication de substrat isolant transmettant la lumière portant une électrode transparente - Google Patents

Substrat de cellule solaire et son procédé de fabrication, cellule solaire à couches minces et son procédé de fabrication, procédé de fabrication de substrat isolant transmettant la lumière portant une électrode transparente Download PDF

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Publication number
WO2013046968A1
WO2013046968A1 PCT/JP2012/070648 JP2012070648W WO2013046968A1 WO 2013046968 A1 WO2013046968 A1 WO 2013046968A1 JP 2012070648 W JP2012070648 W JP 2012070648W WO 2013046968 A1 WO2013046968 A1 WO 2013046968A1
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WIPO (PCT)
Prior art keywords
solar cell
substrate
insulating substrate
light
etching
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English (en)
Japanese (ja)
Inventor
泰 折田
匠 中畑
伸吾 友久
細野　彰彦
本並　薫
藤原　伸夫
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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Priority to JP2013536053A priority Critical patent/JP5666004B2/ja
Publication of WO2013046968A1 publication Critical patent/WO2013046968A1/fr
Anticipated expiration legal-status Critical
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    • 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
    • H10F10/17—Photovoltaic cells having only PIN junction potential barriers
    • H10F10/172—Photovoltaic cells having only PIN junction potential barriers comprising multiple PIN junctions, e.g. tandem 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
    • H10F19/00—Integrated devices, or assemblies of multiple devices, comprising at least one photovoltaic cell covered by group H10F10/00, e.g. photovoltaic modules
    • H10F19/30—Integrated devices, or assemblies of multiple devices, comprising at least one photovoltaic cell covered by group H10F10/00, e.g. photovoltaic modules comprising thin-film photovoltaic cells
    • H10F19/31—Integrated devices, or assemblies of multiple devices, comprising at least one photovoltaic cell covered by group H10F10/00, e.g. photovoltaic modules comprising thin-film photovoltaic cells having multiple laterally adjacent thin-film photovoltaic cells deposited on the same substrate
    • 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
    • H10F19/00—Integrated devices, or assemblies of multiple devices, comprising at least one photovoltaic cell covered by group H10F10/00, e.g. photovoltaic modules
    • H10F19/30—Integrated devices, or assemblies of multiple devices, comprising at least one photovoltaic cell covered by group H10F10/00, e.g. photovoltaic modules comprising thin-film photovoltaic cells
    • H10F19/31—Integrated devices, or assemblies of multiple devices, comprising at least one photovoltaic cell covered by group H10F10/00, e.g. photovoltaic modules comprising thin-film photovoltaic cells having multiple laterally adjacent thin-film photovoltaic cells deposited on the same substrate
    • H10F19/35—Structures for the connecting of adjacent photovoltaic cells, e.g. interconnections or insulating spacers
    • 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
    • H10F77/70—Surface textures, e.g. pyramid structures
    • H10F77/707—Surface textures, e.g. pyramid structures of the substrates or of layers on substrates, e.g. textured ITO layer on a glass substrate
    • 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
    • Y02E10/548—Amorphous silicon PV cells

Definitions

  • the present invention relates to a solar cell substrate, a manufacturing method thereof, and a thin film solar cell.
  • a concavo-convex shape called texture is formed in the cell on the sunlight incident surface side, the light taken into the cell is scattered, the optical path length is lengthened, and the light absorption amount of the power generation layer is increased.
  • the structure to be used is generally adopted.
  • a method for forming the concavo-convex shape after forming the transparent electrode layer on the flat transparent insulating substrate, the method of forming the concavo-convex shape on the film surface of the transparent electrode layer by etching, and the surface of the transparent insulating substrate directly Two methods are generally known: a method of forming a film constituting a cell after forming a cell.
  • ZnO: Al is formed on a flat insulating transparent substrate by sputtering at room temperature, and then etched with a 0.5% aqueous hydrochloric acid solution for about 30 seconds. The texture is formed. At this time, the light scattering characteristic of the texture is determined by the difference in the unevenness depth due to the difference in the etching time of ZnO: Al (for example, Non-Patent Document 1).
  • a glass substrate is subjected to a sand blast treatment or a plasma treatment, and then a wet etching treatment is performed, thereby having a pitch of 0.1 to 5 ⁇ m, and A fine concavo-convex shape having an average inclination angle in the range of 5 to 10 degrees is formed (for example, see Patent Document 1).
  • abrasive grains are sprayed on the surface of the flexible substrate in an air stream, and sandblasting is performed to continuously form unevenness with a height difference of about 0.1 to 0.5 ⁇ m.
  • An unevenness is formed on the surface of the substrate, and a solar cell substrate provided with a scattering reflection surface having an uneven shape suitable for an amorphous Si solar cell is formed (for example, see Patent Document 2).
  • JP 2003-69059 A Japanese Patent No. 3431769
  • Non-Patent Document 1 it is necessary to form a film so that the film quality of the transparent electrode layer is uniform, and to control the etching solution concentration and temperature so that the etching proceeds uniformly. Process management is difficult. Therefore, there is a problem that it is difficult to form a transparent electrode layer having a stable light scattering characteristic with respect to wavelengths in a wide wavelength range from a short wavelength to a long wavelength of visible light with a stable yield. Further, since the transparent electrode layer once formed is removed by etching, there is a problem that it is wasteful from the viewpoint of cost reduction.
  • a transparent electrode layer is formed after sandblasting the glass substrate.
  • the unevenness of the glass substrate is too large, a crystal grain boundary is generated in the transparent electrode layer and the conductivity is increased. There was a problem of being lowered. Therefore, reducing the particle size of the abrasive to reduce the unevenness reduces the light confinement effect, and if wet etching is performed to smooth the unevenness, the uneven pitch increases and light scattering for a long wavelength. There was also a problem that the effect was reduced.
  • the present invention has been made in view of the above, and has a high scattering effect on light from a short wavelength region of visible light to a near infrared wavelength region, and can suppress a decrease in conductivity. It is an object of the present invention to obtain a solar cell substrate capable of forming an electrode layer with a stable yield and a manufacturing method thereof, a thin film solar cell and a manufacturing method thereof, and a manufacturing method of a transparent insulating substrate with a transparent electrode.
  • a solar cell substrate according to the present invention is a solar cell substrate made of a transparent insulating material having irregularities formed on the surface, and is obtained by histogram analysis of the surface shape with the irregularities formed thereon.
  • the depth distribution is distributed in the range of 0.75 ⁇ m to 0.9 ⁇ m, has a peak in the vicinity of 0.85 ⁇ m, and has a distribution shape in which the half width of the peak is 0.03 ⁇ m or more. .
  • the depth distribution obtained by histogram analysis of the surface shape on which the irregularities are formed is distributed in the range of 0.75 ⁇ m to 0.9 ⁇ m and has a peak in the vicinity of 0.85 ⁇ m, and Since the surface of the solar cell substrate is provided with irregularities so that the peak half-value width is 0.03 ⁇ m or more, the light from the short wavelength region of visible light to the near infrared wavelength region is applied.
  • a solar cell substrate having a high light scattering effect can be obtained. As a result, it has a high light scattering effect on the light from the short wavelength region of visible light to the near infrared wavelength region on the uneven surface of the solar cell substrate and acts as a defect.
  • the transparent electrode layer in which the generation of crystal grain boundaries is suppressed can be formed with a stable yield.
  • FIG. 1 is a plan view showing a schematic configuration of a thin film solar cell module according to Embodiment 1 of the present invention.
  • FIG. 2 is a cross-sectional view taken along the line AA in FIG.
  • FIG. 3 is a cross-sectional view of a main part for explaining the texture structure in the thin film solar cell module of FIG.
  • FIG. 4-1 is a cross-sectional view schematically showing an example of a manufacturing process of the thin-film solar cell according to Embodiment 1 (Part 1).
  • FIG. 4-2 is a sectional view schematically showing an example of a manufacturing process of the thin-film solar battery according to Embodiment 1 (part 2).
  • FIG. 1 is a plan view showing a schematic configuration of a thin film solar cell module according to Embodiment 1 of the present invention.
  • FIG. 2 is a cross-sectional view taken along the line AA in FIG.
  • FIG. 3 is a cross-sectional view of a main part for explaining the texture structure in the thin film
  • FIG. 4-3 is a sectional view schematically showing an example of a manufacturing process of the thin-film solar battery according to Embodiment 1 (part 3).
  • FIG. 5 is an AFM (Atomic Force Microscope) image showing a surface shape when a transparent electrode layer is formed on a roughened translucent insulating substrate.
  • FIG. 6 is a diagram showing the frequency of the spatial frequency obtained by Fourier transform analysis of the surface shape data.
  • FIG. 7 is a diagram showing the depth distribution obtained by analyzing the surface shape data by histogram analysis.
  • FIG. 8 is a diagram showing a depth distribution obtained by histogram analysis of the surface shape in the case of the AZO texture method in which pinholes are formed.
  • FIG. 5 is an AFM (Atomic Force Microscope) image showing a surface shape when a transparent electrode layer is formed on a roughened translucent insulating substrate.
  • FIG. 6 is a diagram showing the frequency of the spatial frequency obtained by Fourier transform analysis of the surface shape data.
  • FIG. 7 is
  • FIG. 9 is a diagram showing the ratio of the haze ratio when formed by the glass texture method according to the embodiment to the haze ratio when formed by the conventional AZO texture method.
  • FIG. 10 is a cross-sectional view schematically showing another example of the structure of the thin-film solar battery according to the embodiment.
  • FIG. 11 is a diagram showing evaluation results of solar cell characteristics of a thin film solar cell formed by the glass texture method according to Embodiment 1 and a thin film solar cell formed by a conventional AZO texture method as a comparative example.
  • FIG. 12 is a flowchart for explaining a transparent conductive film forming step in the manufacturing process of the thin-film solar cell according to the first embodiment of the present invention.
  • FIG. 13 is a schematic diagram illustrating an example of a manufacturing apparatus according to the second embodiment of the present invention.
  • FIG. 14 is a characteristic diagram showing the wavelength dependence of the haze ratio of glass substrates whose surfaces are roughened by different methods.
  • FIG. 15 is a characteristic diagram showing the wavelength dependence of the haze ratio of glass substrates with a transparent conductive film having an uneven structure formed by different methods.
  • FIG. 16 is sectional drawing which shows typically an example of the manufacturing process of the solar cell substrate concerning Embodiment 3 of this invention.
  • FIG. 17 is a diagram illustrating the frequency of the spatial frequency obtained by performing Fourier transform analysis on the surface shape data of the glass texture formed by the glass texture method according to the third embodiment of the present invention.
  • FIG. 18 is a diagram showing the frequency of the spatial frequency obtained by Fourier transform analysis of the surface shape data of the glass texture formed by the conventional glass texturing method.
  • FIG. 19 is a characteristic view which shows the haze rate of the solar cell board
  • FIG. 20 is sectional drawing which shows typically an example of the manufacturing process of the thin film solar cell concerning Embodiment 4 of this invention.
  • a solar cell substrate and a manufacturing method thereof a thin film solar cell and a manufacturing method thereof, and a manufacturing method of a transparent insulating substrate with a transparent electrode will be described in detail with reference to the accompanying drawings.
  • the present invention is not limited to the embodiments.
  • the sectional view of the photovoltaic device used in the following embodiments is a schematic one, and the relationship between the thickness and width of the layer, the ratio of the thickness of each layer, and the like may be different from the actual ones. .
  • FIG. 1 is a plan view showing a schematic configuration of a thin-film solar cell module according to Embodiment 1 of the present invention
  • FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1
  • FIG. 3 is a thin-film solar cell of FIG. It is principal part sectional drawing for demonstrating the texture structure in a battery module.
  • this thin-film solar cell module (hereinafter referred to as a module) 1 is a strip-shaped (rectangular) solar cell on a surface on which a texture structure of a translucent insulating substrate 2 is formed.
  • a plurality of battery cells (hereinafter referred to as cells) C are provided, and the cells C are electrically connected in series.
  • the cell C includes a transparent electrode layer 3 as a first electrode layer, a first photoelectric conversion layer 4 as a thin film semiconductor layer, an intermediate layer 5, and a thin film semiconductor on a translucent insulating substrate 2. It has a structure in which a second photoelectric conversion layer 6 as a layer and a back electrode layer 7 as a second electrode layer are sequentially stacked, and a tandem structure in which two photoelectric conversion layers are stacked.
  • the transparent electrode layer 3 formed on the translucent insulating substrate 2 includes a translucent insulating substrate that extends in a direction substantially parallel to the short side direction (left-right direction in FIG. 1) of the translucent insulating substrate 2. Striped first grooves D1 reaching 2 are formed at predetermined intervals in the longitudinal direction of the translucent insulating substrate 2 (vertical direction in FIG. 1). The transparent electrode layers 3 of the adjacent cells C are separated from each other by the first groove D1. In this way, a part of the transparent electrode layer 3 is separated for each cell C so as to straddle the adjacent cells C.
  • the first photoelectric conversion layer 4, the intermediate layer 5, and the second photoelectric conversion layer 6 formed on the transparent electrode layer 3 are substantially parallel to the first groove D1 at a location adjacent to the first groove D1.
  • the second grooves D2 thus formed are formed at predetermined intervals in the longitudinal direction of the translucent insulating substrate 2.
  • the back electrode layer 7 is formed up to the transparent electrode layer 3 along the cross-sectional side walls of the first photoelectric conversion layer 4, the intermediate layer 5, and the second photoelectric conversion layer 6. .
  • the back electrode layer 7 is connected to the transparent electrode layer 3 by forming the back electrode layer 7 on the side walls of the first photoelectric conversion layer 4, the intermediate layer 5, and the second photoelectric conversion layer 6.
  • this transparent electrode layer 3 straddles the adjacent cell C, in two adjacent cells C, the back electrode layer 7 of one cell C and the transparent electrode layer 3 of the other cell C are electrically connected. Is done.
  • the back electrode layer 7, the second photoelectric conversion layer 6, the intermediate layer 5, and the first photoelectric conversion layer 4 are different from the first groove D1 and the second groove D2 in the translucent insulating substrate 2.
  • Striped third grooves (separation grooves) D3 reaching the surface are formed at predetermined intervals in the longitudinal direction of the translucent insulating substrate 2 substantially in parallel with the first and second grooves D1 and D2. Yes.
  • the transparent electrode layer 3 and the back electrode layer 7 are separated so as not to be short-circuited.
  • the transparent electrode layer 3 of the cell C is connected to the back electrode layer 7 of the adjacent cell C, whereby the adjacent cells C are electrically connected in series.
  • the translucent insulating substrate 2 has high transmittance from, for example, visible light to the near infrared region, and absorbs from visible light to the near infrared region.
  • An insulating substrate having a light-transmitting property such as a small glass substrate is used.
  • a texture structure to be described later is provided on the surface of the translucent insulating substrate 2 on the side where the cells C are formed.
  • the texture structure formed on the translucent insulating substrate 2 has a frequency of spatial frequency obtained by Fourier transforming surface shape information (data) obtained from AFM (Atomic Force Microscope) measurement at 1.0 ⁇ m or more and 1.2 ⁇ m. It has a peak in the following range (around 1.1 ⁇ m), and the frequency of 0.4 ⁇ m is 1 / more than 1/4 of the peak frequency in the range of 1.0 ⁇ m or more and 1.2 ⁇ m or less (around 1.1 ⁇ m).
  • the texture structure is formed to be 2 or less.
  • the depth distribution obtained by analyzing the surface shape by histogram analysis is within 0.75 ⁇ m to 0.90 ⁇ m, has a peak in the vicinity of 0.85 ⁇ m, and its half width is 0.03 ⁇ m or more. Has been.
  • This texture structure has a function to scatter incident sunlight and increase the light use efficiency in the cell C (the first photoelectric conversion layer 4 and the second photoelectric conversion layer 6). Specifically, the light incident from the back surface of the light-transmitting insulating substrate 2 (the surface facing the cell C forming surface) is scattered at the interface between the light-transmitting insulating substrate 2 and the transparent electrode layer 3 having irregularities. After that, since it enters the cell C, it enters the cell C almost obliquely. When light is incident obliquely, the substantial optical path of the light is extended and the light absorption is increased. Therefore, the photoelectric conversion characteristics of the cell C are improved, the output current is increased, and the incident light is absorbed more efficiently. And has a function of increasing the light use efficiency.
  • the transparent electrode layer 3 only needs to be a transparent conductive film having optical transparency, and zinc oxide (ZnO), indium tin oxide (ITO), tin oxide (SnO 2 ), and zirconium oxide (ZrO). 2 ) transparent conductive oxide films mainly composed of crystalline metal oxides such as aluminum (Al), gallium (Ga), indium (In), boron (B) as dopants in these transparent conductive oxide films , A film to which at least one element selected from yttrium (Y), silicon (Si), zirconium (Zr), and titanium (Ti) is added, or a transparent conductive film formed by stacking these elements is used. it can.
  • ZnO zinc oxide
  • ITO indium tin oxide
  • SnO 2 tin oxide
  • ZrO zirconium oxide
  • the first photoelectric conversion layer 4 is disposed behind the transparent electrode layer 3 when viewed from the light incident side, and has a pin structure in which a p-type semiconductor layer 4a, an i-type semiconductor layer 4b, and an n-type semiconductor layer 4c are sequentially stacked from the light incident side. It is comprised by the thin film semiconductor layer which produces electric power with incident light.
  • the second photoelectric conversion layer 6 is disposed on the first photoelectric conversion layer 4 via the intermediate layer 5, and the p-type semiconductor layer 6a, the i-type semiconductor layer 6b, and the n-type semiconductor layer 6c are sequentially formed from the light incident side.
  • the thin film semiconductor layer has a stacked pin structure and generates power by incident light.
  • the first photoelectric conversion layer 4 disposed on the light incident side has a relative band gap.
  • a photoelectric conversion layer made of a wide material such as an amorphous silicon material is used.
  • the second photoelectric conversion layer 6 disposed on the rear side includes a material having a relatively narrow band gap than the first photoelectric conversion layer 4, for example, a photoelectric conversion layer formed of a microcrystalline silicon-based material, amorphous silicon germanium, or the like. The photoelectric conversion layer comprised by these is used.
  • a laminated film in which an n-type semiconductor layer 4c made of an n-type amorphous silicon film (a-Si film) is laminated can be used.
  • a laminated film in which an i-type semiconductor layer 4b and an n-type semiconductor layer 4c made of an n-type hydrogenated microcrystalline silicon film ( ⁇ c-Si: H film) are laminated can also be used.
  • the electrical and optical connections between the pin junctions are improved between the respective pin junctions.
  • the intermediate layer 5 made of a film having both light transmitting and light reflecting properties and having conductivity may be provided as necessary. Since the intermediate layer 5 can reflect the light incident on the first photoelectric conversion layer 4, there is an effect of increasing the effective film thickness of the first photoelectric conversion layer 4. As a result, the output current density of the first photoelectric conversion layer 4 and the second photoelectric conversion layer 6 can be adjusted, and the module characteristics can be improved.
  • a transparent film having conductivity such as oxidized microcrystalline silicon ( ⁇ c-SiO x ), aluminum-added zinc oxide (ZnO: Al), zinc oxide, indium tin oxide, tin oxide, silicon oxide (SiO), or the like. Can be used.
  • the intermediate layer 5 may be a single layer film or a laminated film in which a plurality of films having different refractive indexes are laminated.
  • the back electrode layer 7 is composed of a metal film such as silver (Ag), aluminum or silver alloy having high conductivity and high reflectivity.
  • a metal film such as silver (Ag), aluminum or silver alloy having high conductivity and high reflectivity.
  • the second photoelectric conversion layer 6 is made of, for example, silicon
  • a laminated film of a transparent conductive oxide film mainly composed of a crystalline metal oxide such as zirconium oxide and a metal film such as silver, aluminum, or a silver alloy film may be used.
  • a surface texture structure in which irregularities are formed by applying a roughening process to the surface of the back electrode layer 7 by a blast method, a wet etching method, a dry etching method, or the like may be applied.
  • the module 1 even when the film thickness of the first photoelectric conversion layer 4 which is an amorphous silicon thin film semiconductor layer is thin, the module 1 has a good covering property, so that it is laminated thereon. It becomes easy to control the current value matching with the second photoelectric conversion layer 6 which is a microcrystalline silicon thin film photoelectric conversion layer by the film thickness of the first photoelectric conversion layer 4, and a thin film solar cell having higher photoelectric conversion efficiency is obtained. Can be realized.
  • FIGS. 4-1 to 4-3 are cross-sectional views schematically showing an example of the manufacturing process of the thin-film solar cell according to the embodiment.
  • a translucent insulating substrate 2 is prepared.
  • an alkali glass substrate is used as the translucent insulating substrate 2 will be described below.
  • the translucent insulating substrate 2 is subjected to alkali or acid cleaning to sufficiently remove the dirt on the substrate surface. If dirt remains on the translucent insulating substrate 2, it will cause a concavo-convex formation defect in a subsequent concavo-convex formation process, and thus it is desirable to perform sufficient cleaning.
  • the translucent insulating substrate 2 is carried into a chamber where etching is performed, protecting the back surface of the translucent insulating substrate 2 (surface facing the formation surface of the cell C) with a resist so as not to be etched.
  • the back surface of the translucent insulating substrate 2 is brought into close contact with a stage that holds the substrate in an etching chamber so that the etching gas is not exposed to the back surface. Is also effective.
  • etching is performed by exposing the surface of the light-transmitting insulating substrate 2 to hydrogen fluoride gas, thereby forming irregularities 2 a on the surface of the light-transmitting insulating substrate 2.
  • SiO 2 is vaporized as SiF 4 by the reaction represented by the following reaction formula (1).
  • impurities such as sodium, aluminum oxide, calcium oxide, magnesium oxide, and iron oxide, which are contained in the alkali glass substrate as a whole in 30 to 40% and exist in the SiO 2 bond lattice, react with hydrogen fluoride. And becomes a non-volatile fluoride.
  • This nonvolatile fluoride serves as a mask, and SiO 2 constituting the alkali glass substrate is etched. That is, a portion that is easily etched and a portion that is difficult to etch are generated, and the unevenness 2a is formed on the surface of the alkali glass substrate.
  • the fluoride fluoride of impurities contained in the glass substrate serving as a mask remains as it is without being lifted off as in the case of hydrofluoric acid, so that it functions as a mask. To do. Furthermore, in the case of hydrogen fluoride gas, since the etching reaction proceeds at the molecular level, fine irregularities are formed on the glass surface, and short-period irregularities are easily formed by stacking the fine irregularities. This is more effective than a non-alkali glass substrate having a high etching rate.
  • irregularities 2a having a size of about 10 nm to 10 ⁇ m, for example, are generated on the surface of the translucent insulating substrate 2, and the wavelength is about 300 nm to 1100 nm.
  • a surface texture structure having good scattering characteristics for a wide range of wavelengths of light is formed.
  • the etching depth on the surface of the translucent insulating substrate 2 is less than 0.5 ⁇ m, only irregularities of about 10 nm are formed. Further, when the etching depth on the surface of the translucent insulating substrate 2 is larger than 10 ⁇ m, the uneven distribution is not uniform and is uneven in the plane of the translucent insulating substrate 2.
  • the unevenness 2a is formed on both surfaces of the translucent insulating substrate 2, but the unevenness 2a is formed only on one surface of the translucent insulating substrate 2 by protecting one surface of the translucent insulating substrate 2 or the like. May be formed.
  • Etching may be performed at normal pressure, but by performing etching under reduced pressure, the controllability of etching is improved, and the surface of the translucent insulating substrate 2 can be uniformly etched.
  • the pressure during decompression is preferably reduced to about 100 Pa to 10,000 Pa. When the pressure during etching is less than 100 Pa, only irregularities of about 10 nm are formed. When the pressure at the time of etching is larger than 10,000 Pa, the uneven distribution is not uniform and is uneven in the plane of the translucent insulating substrate 2.
  • the etching residue remaining on the surface of the translucent insulating substrate 2 is removed by washing with water, for example.
  • an alkali glass substrate is used as the translucent insulating substrate 2
  • an inexpensive blue plate glass substrate may be used.
  • a method for forming the SiO 2 film for example, a physical method such as a sputtering method, a vacuum deposition method, or an ion plating method, or a chemical method such as a spray method, a dip method, or a CVD (Chemical Vapor Deposition) method is used. Can do.
  • FIG. 4B a 1 ⁇ m-thick zinc oxide film containing aluminum as a 0.6 at% dopant is formed on the roughened translucent insulating substrate 2 as the transparent electrode layer 3.
  • the film is formed at a film forming temperature of 300 ° C. by DC sputtering.
  • a transparent conductive film having a target resistivity of 0.5 m ⁇ / cm 2 or less is obtained when the concentration is low.
  • FIG. 5 is an AFM (Atomic Force Microscope) image showing a surface shape when a transparent electrode layer is formed on a roughened translucent insulating substrate.
  • the surface after forming the transparent electrode layer 3 has the unevenness 3a similar to the translucent insulating substrate 2, reflecting the rough surface (unevenness 2a) of the translucent insulating substrate 2.
  • a zinc oxide film containing aluminum as a dopant is formed as the transparent electrode layer 3 by a sputtering method.
  • the transparent electrode layer 3 is not limited to this, and indium tin oxide, tin oxide and oxide Transparent conductive oxide film mainly composed of crystalline metal oxide such as zirconium, and at least selected from aluminum, gallium, indium, boron, yttrium, silicon, zirconium and titanium as a dopant in these transparent conductive oxide films A film to which one or more elements are added or a transparent conductive film formed by stacking these elements may be used.
  • the transparent electrode layer 3 is formed using a physical method such as a vacuum deposition method or an ion plating method, or a chemical method such as a spray method, a dip method, or a CVD method. can do.
  • the surface shape data is obtained by measuring with AFM.
  • AFM measurement applies a measurement method generally called DFM (Dynamic Force Mode) mode in which a cantilever is excited and scans the surface of the sample, and the tip diameter of the cantilever is 10 nm.
  • the scan range is 25 ⁇ m square, the sampling number is 512 ⁇ 512, and the speed for scanning one line is 1.2 sec / line (0.83 Hz).
  • the sensitivity adjustment of the cantilever is adjusted so that the height waveform and the deviation waveform of the forward path and the return path of the cantilever have the same shape. Depending on the shape, the height waveform and the deviation waveform may not show the same shape at the scan speed, and in this case, the scan speed is adjusted.
  • FIG. 6 is a diagram showing the frequency of the spatial frequency obtained by Fourier transform analysis of the surface shape data
  • FIG. 7 is a diagram showing the depth distribution obtained by histogram analysis of the surface shape data.
  • the horizontal axis indicates the most frequent spatial frequency ( ⁇ m)
  • the vertical axis indicates the frequency ( ⁇ 10 9 ).
  • the horizontal axis represents the texture depth (concave / convex height difference) ( ⁇ m)
  • the vertical axis represents the frequency ( ⁇ 10 3 ).
  • the depth distribution ranges from 0.75 ⁇ m to 0.9 ⁇ m, has a peak in the vicinity of 0.85 ⁇ m, and does not decrease rapidly from the maximum value to the minimum value. Have a distribution that changes over time. Moreover, the peak has a half value in about 0.81 micrometer and 0.87 micrometer, and the half value width is a single peak of about 0.06 micrometer.
  • the frequency of the spatial frequency at 0.3 to 1.5 ⁇ m which is a periodic component that scatters light in the visible light region, is 1.1 ⁇ m, 0.85 ⁇ m, 0.7 ⁇ m, and 0.63 ⁇ m. , 0.55 ⁇ m, 0.48 ⁇ m, 0.45 ⁇ m, and 0.4 ⁇ m.
  • the intensity of the shortest peak in the vicinity of 0.4 ⁇ m is more than one quarter and 2 minutes of the longest peak in the range of 1.0 to 1.3 ⁇ m (near 1.1 ⁇ m). It can be seen that a concavo-convex shape of 1 or less can be formed on the translucent insulating substrate 2.
  • FIG. 8 is a diagram showing a depth distribution obtained by histogram analysis of the surface shape in the case of the AZO texture method in which pinholes are formed.
  • the horizontal axis indicates the depth of texture (the height difference of the unevenness) ( ⁇ m), and the vertical axis indicates the frequency ( ⁇ 10 3 ).
  • the depth distribution is in the range of 0.80 ⁇ m or more and 0.85 ⁇ m or less, and the distribution sharply decreases near the peak of 0.85 ⁇ m.
  • the half width is 0.02 ⁇ m or less, which is narrower than in the case of the embodiment shown in FIG. This is because pinholes are generated in the transparent electrode layer 3 and there are no recesses deeper than that.
  • the depth distribution in the method of forming a texture on the glass substrate according to Embodiment 1 has a wide depth distribution of 0.75 to 0.9 ⁇ m.
  • the presence of depth distribution means that the inclination angles of the unevenness are various. That is, the scattered light is spread and scattered at various angles, and the optical scattering effect is further improved.
  • the half width of the peak of the depth distribution is preferably at least 0.03 ⁇ m or more, and more preferably 0.05 ⁇ m or more. This is because if the half width of the peak is less than 0.03 ⁇ m, the change (distribution shape) of the peak becomes steep as shown in FIG. 8, and a desired optical scattering effect cannot be obtained. Further, if the half width of the peak of the depth distribution is 0.03 ⁇ m or more, preferably 0.05 ⁇ m or more, the change of the peak of the depth distribution is smooth as in the embodiment, and the inclination angle of the unevenness is various. Thus, a desired optical scattering effect can be obtained.
  • the distribution curve has a curvature near the peak position. Furthermore, the difference between the texture depth at the peak of the distribution curve and the texture depth at the point where the distribution curve intersects the horizontal axis, relative to the absolute value of the difference in texture depth at the two points where the distribution curve intersects the horizontal axis. It is desirable that the ratio of the absolute values of is about 0.1 to 0.6. When this ratio is less than 0.1, a steep peak shape is formed as shown in FIG. 8, and a desired optical scattering effect cannot be obtained.
  • FIG. 9 is a diagram showing the ratio of the haze ratio when formed by the glass texture method according to Embodiment 1 to the haze ratio when formed by the conventional AZO texture method.
  • the horizontal axis indicates the wavelength of light used for measuring the haze ratio
  • the vertical axis indicates the haze ratio (H 0 ) of the unevenness (comparative example 1) according to the conventional AZO texture method as comparative example 1.
  • 1 shows the ratio (H b / H 0 ) of the haze ratio (H b ) of the unevenness 3 a (Example 1) by the glass texture method according to 1.
  • the unevenness 2a formed on the roughened translucent insulating substrate 2 of the first embodiment is more uneven than the unevenness formed by the method described in Non-Patent Document 1.
  • Both the depth and pitch have a wide distribution range.
  • a wider unevenness distribution means that various unevenness angle components exist, and a deeper unevenness means a higher haze ratio.
  • the more types of peaks in the most frequent spatial period the more scattering the light with various wavelengths. The larger the most frequent spatial period, the longer the wavelength of light in the visible light region is scattered. Means there is.
  • the visible light has a short wavelength region to a near infrared wavelength region. It is possible to efficiently scatter light up to. Moreover, in the transparent electrode layer 3 formed on the translucent insulating substrate 2 having a shape in which long-period and short-period irregularities are mixed, the generation of crystal grain boundaries that act as defects is suppressed, and the conductivity is improved. It is also possible to prevent a decrease in the above.
  • an etching method using hydrogen fluoride gas has been shown as a method for roughening the surface of the light-transmitting insulating substrate 2, but the present invention is not limited to this, and fluorine gas is used in plasma. Alternatively, an etching method for generating the above may be used. At this time, for example, tetrafluoromethane (CF 4 ), trifluoride methane (CHF 3 ), difluoride methane (CH 2 F 2 ), hexafluoroethane (C 2 F 6 ), octafluoride can be used as an etching gas.
  • CF 4 tetrafluoromethane
  • CHF 3 trifluoride methane
  • difluoride methane CH 2 F 2
  • hexafluoroethane C 2 F 6
  • octafluoride can be used as an etching gas.
  • Propane (C 3 F 8 ), perfluorocyclobutane (C 4 F 8 ), sulfur hexafluoride (SF 6 ) and the like can be used.
  • these etching gases water and alcohol become reaction initiators by mixing a small amount of water or alcohol in the plasma, and hydrogen fluoride is generated.
  • the generation of hydrogen fluoride by plasma exposure may be performed in vacuum or at atmospheric pressure, but the generation efficiency of hydrogen fluoride is better in vacuum, and the etching rate of SiO 2 can be increased.
  • Ar or N 2 is used as a carrier gas, and a highly polar material such as water or alcohol is used as a stabilizer that makes it difficult to condense in the carrier gas. Be exposed.
  • the transparent electrode layer 3 is patterned into strips and separated into a plurality of transparent electrode layers 3 as shown in FIG. To do.
  • the first groove D1 extending in a direction substantially parallel to the transversal direction of the translucent insulating substrate 2 is formed in a stripe shape in the transparent electrode layer 3, and the transparent electrode layer 3 is cut and removed. , Can be patterned into strips.
  • a resist mask formed by a laser scribing method, a photolithography technique, or the like It is possible to use a method such as an etching method using metal or a vapor deposition method using a metal mask.
  • the first photoelectric conversion layer 4 in which the p-type semiconductor layer 4a, the i-type semiconductor layer 4b, and the n-type semiconductor layer 4c are stacked on the transparent electrode layer 3 is subjected to plasma. It is formed by the CVD method.
  • a p-type amorphous silicon carbide film is used as the p-type semiconductor layer 4a
  • an i-type amorphous silicon film is used as the i-type semiconductor layer 4b
  • an n-type amorphous silicon film is used as the n-type semiconductor layer 4c.
  • an intermediate layer 5 made of a transparent conductive material is formed on the first photoelectric conversion layer 4.
  • the intermediate layer 5 is composed of a film having both light transmission and light reflection characteristics and conductivity.
  • a film of zinc oxide, indium tin oxide, tin oxide, silicon monoxide or the like formed by a plasma CVD method or the like can be used.
  • what is necessary is just to provide this intermediate
  • the second photoelectric conversion layer 6 in which the p-type semiconductor layer 6a, the i-type semiconductor layer 6b, and the n-type semiconductor layer 6c are stacked on the intermediate layer 5 is formed by plasma CVD.
  • a p-type microcrystalline silicon film is used as the p-type semiconductor layer 6a
  • an i-type microcrystalline silicon film is used as the i-type semiconductor layer 6b
  • an n-type microcrystalline silicon film is used as the n-type semiconductor layer 6c.
  • the second groove D2 parallel to the groove D1 is formed in a stripe shape and patterned into a strip shape.
  • the second groove D2 is provided at a position different from the position where the first groove D1 is formed.
  • the transparent electrode layer 3 is exposed at the bottom of the second groove D2.
  • a method such as a laser scribing method, a method of etching using a resist mask formed by a photolithography technique, a vapor deposition method using a metal mask, or the like can be used.
  • the scattered matter adhering in the second groove D2 is removed by high-pressure water cleaning, megasonic cleaning, or brush cleaning.
  • the back electrode layer 7 is formed on the second photoelectric conversion layer 6 and in the second groove D2.
  • a silver alloy film having a film thickness of 200 nm can be used.
  • a transparent conductive film such as zinc oxide, indium tin oxide, tin oxide or the like is provided on the second photoelectric conversion layer 6.
  • a laminated structure in which a metal film such as a silver alloy film is provided may be used.
  • a metal film it can be formed by a film forming method such as sputtering, CVD, or spray.
  • a transparent conductive film it can be formed by a method such as plasma CVD.
  • a third groove D3 parallel to the first and second grooves D1 and D2 is formed in a stripe shape at a position different from the first and second grooves D1 and D2, and is patterned into a strip shape.
  • Such a third groove D3 can be formed by a laser scribing method, a method of etching using a resist mask formed by a photolithography technique or the like, or a vapor deposition method using a metal mask.
  • the scattered matter adhering in the third groove D3 is removed by high-pressure water cleaning, megasonic cleaning, or brush cleaning. Thereby, a plurality of separated cells C are formed.
  • the third groove D3 is formed by the laser scribing method, it is difficult to directly absorb the laser light in the back electrode layer 7 having a high reflectivity, and thus the semiconductor layer (the first photoelectric conversion layer 4 and the second photoelectric conversion layer).
  • the layer 6) absorbs the energy of the laser light, and the back electrode layer 7 is blown locally together with the semiconductor layer, so that it can be separated into a plurality of unit elements (power generation regions), that is, a plurality of cells C.
  • the module 1 having the cell C having the structure shown in FIGS. 1 to 3 is completed.
  • amorphous silicon is used for the first photoelectric conversion layer 4 and microcrystalline silicon is used for the second photoelectric conversion layer 6 as shown in FIG. 3
  • amorphous silicon germanium is used.
  • the amorphous silicon semiconductor layer such as amorphous silicon carbide and the crystalline silicon semiconductor layer
  • the first photoelectric conversion layer 4 and the second photoelectric layer shown in FIGS. 2 and 3 are used.
  • a two-layer tandem module 1 having a conversion layer 6 can also be configured. Good characteristics can be obtained by using a pin structure using these semiconductor layers. Further, the present invention is not limited to the two-layer tandem type module 1.
  • FIG. 10 is a cross-sectional view schematically showing another example of the structure of the thin-film solar battery according to the first embodiment.
  • the first photoelectric conversion layer 4 in FIG. 3 is formed by converting the p-type semiconductor layer 41a, the i-type semiconductor layer 41b, and the n-type semiconductor layer 41c into a stacked layer, p Formed by two photoelectric conversion layers 41 and 42 of a photoelectric conversion layer 42 in which a type semiconductor layer 42a, an i-type semiconductor layer 42b, and an n-type semiconductor layer 42c are stacked, and gradually from the translucent insulating substrate 2 side.
  • a three-layer tandem module configured to widen the band gap of the photoelectric conversion layer can also be configured.
  • the photoelectric conversion layer 41 of the first photoelectric conversion layer 4 is made of amorphous silicon
  • the photoelectric conversion layer 42 is made of amorphous silicon germanium
  • the second photoelectric conversion layer 6 is made of crystalline silicon.
  • the power generation layer can also be formed of silicon having different crystallinity.
  • the photoelectric conversion layer 41 of the first photoelectric conversion layer 4 is formed of amorphous silicon
  • the photoelectric conversion layer 42 is also photoelectrically converted.
  • a three-layer tandem module composed of crystalline silicon that is more crystalline than the layer 41 and the second photoelectric conversion layer 6 composed of crystalline silicon that is more crystalline than the photoelectric conversion layer 42. is there. With such a configuration, a thin film solar cell that absorbs light in a wider wavelength range is obtained, and good characteristics can be obtained.
  • tandem-type thin film solar cell has been described as an example.
  • a microcrystalline silicon semiconductor layer or a silicon germanium semiconductor layer doped with germanium is provided as a photoelectric conversion layer. Since the thin film solar cell has light absorption on the long wavelength side, even when only one photoelectric conversion layer 4 is provided, the effect can be obtained by applying this embodiment.
  • FIG. 11 shows a solar cell of a thin film solar cell (Example 2) formed by the glass texture method according to the first embodiment and a thin film solar cell (Comparative Example 2) formed by a conventional AZO texture method as a comparative example. It is a figure which shows the evaluation result of a characteristic. In this figure, the horizontal axis indicates the wavelength (nm) and the vertical axis indicates the quantum efficiency.
  • the thin-film solar cell of Example 2 according to Embodiment 1 includes the first photoelectric conversion layer 4 and microcrystalline silicon made of amorphous silicon on the light-transmitting insulating substrate 2 roughened by the glass texture method described above.
  • the thin film solar cell according to Comparative Example 2 has a tandem type having a first photoelectric conversion layer made of amorphous silicon and a second photoelectric conversion layer made of microcrystalline silicon on a translucent insulating substrate formed with a texture by the AZO texture method. It has the following structure. And quantum efficiency is measured with respect to each thin film solar cell.
  • the absorption coefficient of the power generation layer is low, and it can be confirmed that the quantum efficiency on the long wavelength side is easily affected by the light confinement effect due to increased light diffusion. Also, the short circuit current density increases by 1.23 mA / cm 2 and the fill factor increases by 2.67%. This is because, in the transparent electrode layer 3, the crystallinity is improved and the electric resistance is lowered, the carrier density is improved, and a texture showing good light scattering characteristics in a wide wavelength region can be formed. Conceivable.
  • the optically more effective unevenness 2a particularly the long-period and short-period unevenness. It is possible to form irregularities that are mixed. Thereby, even when the transparent electrode layer 3 is formed on the uneven surface of the translucent insulating substrate 2, it is possible to prevent generation of a crystal grain boundary that acts as a defect of the transparent electrode layer 3, A decrease can be prevented. Moreover, the transparent electrode layer 3 having a high light scattering effect with respect to light in a wide wavelength range from visible light to near infrared can be formed with a stable yield.
  • the photoelectric conversion layers 4 and 6 and the back electrode layer 7 are formed on the transparent electrode layer 3 having such irregularities, a large amount of light is delivered to the photoelectric conversion layers 4 and 6 to confine the light.
  • the photoelectric conversion layers 4 and 6 can absorb more light depending on the effect. Further, since no pinhole is generated in the transparent electrode layer 3, a thin film solar cell having a good photoelectric conversion efficiency can be obtained with a high yield without causing a decrease in open circuit voltage (Voc).
  • the surface of the light-transmitting insulating substrate 2 is etched by exposing the light-transmitting insulating substrate 2 in an atmosphere in which a mixed gas (HF / H 2 O) of water and water vapor (H 2 O) is flowed.
  • a mixed gas HF / H 2 O
  • the unevenness 2a is generated on the surface of the translucent insulating substrate 2, and a glass texture structure is formed.
  • the surface of the translucent insulating substrate 2 is etched using hydrogen fluoride (HF) gas or a mixed gas (HF / H 2 O) of hydrogen fluoride (HF) gas and water vapor (H 2 O) as an etching gas.
  • HF hydrogen fluoride
  • H 2 O water vapor
  • the light scattered by the unevenness 2 a and transmitted through the first photoelectric conversion layer 4 and the second photoelectric conversion layer 6 is reflected by the back electrode layer 7 and returned to the second photoelectric conversion layer 6 and the first photoelectric conversion layer 4 again. Therefore, the light confinement effect is promoted between the unevenness 2a and the back electrode layer 7, and as a result, a solar cell excellent in electric characteristics and optical characteristics can be obtained.
  • the glass texture structure can be formed only by etching the translucent insulating substrate 2.
  • a glass texture structure is formed by subjecting a glass substrate to a plasma treatment or a sand blast treatment, then performing a wet etching treatment, and further washing. That is, in order to form unevenness on the glass substrate, three processes were performed using three manufacturing apparatuses having different uses. For this reason, there existed a problem that cost raised and throughput fell.
  • the method of manufacturing the thin film solar cell according to the first embodiment hydrogen fluoride (HF) gas or hydrogen fluoride (HF) gas and water vapor (H 2 O), a mixed gas (HF / H 2 O) to the Asperities are formed by etching the glass substrate by exposing the transparent insulating substrate 2 (for example, glass substrate) (step S10), and etching residue is removed after etching the transparent insulating substrate 2 (step S20). Since a texture structure can be formed, the cost can be reduced and the throughput can be improved as compared with the conventional structure. Then, by forming a transparent electrode (transparent conductive film) on the translucent insulating substrate 2, a translucent substrate with a transparent electrode capable of realizing a solar cell excellent in electrical characteristics and optical characteristics is obtained (see FIG. 12).
  • a transparent electrode transparent conductive film
  • a resist resin is applied to the surface of the material to be etched and the surface is masked, as in a process called semiconductor photolithography.
  • semiconductor photolithography By forming a portion that is open and a portion that is not open, a portion that is not etched and a portion that is not etched are intentionally formed.
  • the mask material is formed on the surface of the light-transmitting insulating substrate 2 (glass substrate) simultaneously with the etching, the above-described mask formation step is not required, so that cost reduction and throughput are achieved. Improvements can be made.
  • a light confinement structure capable of obtaining a good light confinement effect can be formed efficiently and inexpensively, and a solar cell excellent in electrical characteristics and optical characteristics is efficiently produced. Good and inexpensive.
  • the glass substrate on which the unevenness is formed has many short-period unevenness, it has a reflection reducing effect and can be used as a cover glass for a crystalline solar cell.
  • FIG. 13 is a schematic diagram illustrating an example of a manufacturing apparatus according to the second embodiment, and illustrates an example of a manufacturing apparatus for forming the unevenness 2a on the translucent insulating substrate 2 by the method described in the first embodiment. It is a schematic diagram.
  • the manufacturing apparatus shown in FIG. 13 includes a decompression container 21, a mass flow controller 22-1, a mass flow controller 22-2, a shower head 23, a supply pipe 24-1, a supply pipe 24-2, and a vacuum pump 25. And an exhaust pipe 26.
  • the decompression vessel 21 has a mechanism for accommodating the translucent insulating substrate 2 in a holding portion (not shown) and decompressing the inside of the vessel while being isolated from the outside air. Since the pressure reduction container 21 needs pressure resistance, it is made of a metal material such as stainless steel or aluminum. Further, since the inner surface of the decompression vessel 21 is exposed to the corrosive HF gas 27, it is preferable that a fluorine resin coating having high corrosion resistance is applied.
  • the mass flow controller 22-1 adjusts the gas amount of the HF gas 27 supplied from a gas supply source such as a cylinder, and supplies the HF gas 27 into the decompression vessel 21 through the supply pipe 24-1.
  • Mass flow controller 22-2 adjusts the gas volume of the H 2 O gas (water vapor) 28 supplied from the gas supply source such as a cylinder, the H 2 O gas into the vacuum container 21 through a supply pipe 24-2 (vapor) 28 is supplied.
  • the HF gas 27 and H 2 O gas (water vapor) 28 introduced from the supply pipe 24-1 and the supply pipe 24-2 are connected to the supply pipe 24-1 and the supply pipe 24-2, and are provided in the decompression vessel 21.
  • the shower head 23 is supplied uniformly on the surface of the translucent insulating substrate 2.
  • the vacuum pump 25 is connected to the decompression vessel 21 through the exhaust pipe 26, and the inside of the decompression vessel 21 can be decompressed.
  • the translucent insulating substrate 2 is accommodated in the decompression container 21, and the inside of the decompression container 21 is isolated from the outside air. Thereafter, the vacuum pump 25 is started and the air in the decompression vessel 21 is exhausted through the exhaust pipe 26. After evacuating the inside of the decompression vessel 21 to, for example, a pressure of about 0.01 Pa to 10 Pa, the mass flow controller 22-1 and the mass flow controller 22-2 are adjusted, and the HF gas 27 is introduced into the decompression vessel 21 from a gas supply source such as a cylinder. The HF / H 2 O gas is supplied into the decompression vessel 21 by supplying the HF gas 27 and the H 2 O gas 28 into the decompression vessel 21 from a gas supply source such as a cylinder.
  • the pressure in the decompression vessel 21 is preferably about 100 Pa to 10,000 Pa.
  • the pressure in the decompression vessel 21 is preferably about 100 Pa to 10,000 Pa.
  • the unevenness 2a In order to form the unevenness 2a more efficiently, it is also effective to mix methanol or ethanol into the vacuum container 21 during etching. Since the etching rate can be controlled by mixing methanol or ethanol into the etching gas, the unevenness distribution becomes more uniform.
  • FIG. 14 is a characteristic diagram showing the wavelength dependence of the haze ratio of glass substrates whose surfaces are roughened by different methods.
  • FIG. 14 shows the relationship between the wavelength (nm) of light and the haze ratio (%) for a glass substrate having irregularities formed on the surface by different methods.
  • the haze ratio (%) is a value obtained by measuring the ratio of diffusely transmitted light in the total light transmitted light for each wavelength.
  • plot A is an experimental result (Example 3) in which the surface of the glass substrate is etched by HF gas using the above-described manufacturing apparatus to form irregularities
  • plot B is HF using the above-described manufacturing apparatus.
  • Experimental results of forming irregularities by etching the surface of a glass substrate with gas (Example 4)
  • plot C shows experimental results of forming irregularities by etching the surface of a glass substrate by wet etching using hydrofluoric acid (Comparative Example) 3)
  • Plot D shows the experimental results (Comparative Example 4) in which irregularities were formed by blasting.
  • the etching rate of Example 3 is slower than that of Example 4, and the experiment was performed with different etching rates between Example 3 and Example 4.
  • the etching conditions of Example 3 are those obtained by etching about 5 ⁇ m at a pressure of 100 Pa.
  • the etching conditions of Example 4 are those obtained by etching about 5 ⁇ m at a pressure of 5000 Pa.
  • the haze ratio of the glass substrates of Example 3 and Example 4 is a long wavelength of about 500 nm or more as compared with Comparative Example 3 and Comparative Example 4 in which irregularities were formed by wet etching or blasting using hydrofluoric acid. It can be seen that a value of 40% or more can be obtained even at a wavelength of 1 ⁇ m or more.
  • Example 3 and Example 4 in which the etching rate is different in the etching with HF gas are compared, the higher haze ratio is obtained in Example 3 which is processed under the condition where the etching rate is low.
  • the surface of the glass substrate immediately after the etching of Example 3 and Example 4 was observed, the surface was covered with the etching residue.
  • the etching residue forms a rough layer with fine gaps.
  • a part of the etching residue layer was cracked.
  • the reason why the shapes of the residues are different is unknown, but it is thought that the difference in mean free path of gas molecules based on the difference in pressure between Example 3 and Example 4 may have an effect. Yes.
  • the size of the fine irregularities is about 10 nm to 100 nm.
  • the size of the long-period irregularities is about 10 ⁇ m.
  • the fine recesses and the large recesses formed in this way overlap, so that long-period irregularities and short-period irregularities are mixed on the surface of the glass substrate, and a wide wavelength range from short wavelengths to long wavelengths. It is thought that the haze rate was increased with respect to the light of That is, it is considered that such a residue layer is naturally formed at the time of etching, thereby forming unevenness that provides a good haze ratio, and unevenness caused by etching using blasting, wet etching, plasma, or the like is considered. Compared to formation, a good haze ratio can be easily realized up to a long wavelength.
  • a glass substrate containing at least one of alkali metal, alkaline earth metal, magnesium and aluminum was used.
  • alkali metal include sodium and potassium.
  • alkaline earth metal include calcium.
  • the quartz glass substrate not containing the above metal was also tested using hydrogen fluoride (HF) gas as an etching gas.
  • HF hydrogen fluoride
  • the unevenness 2a in which long-period unevenness and short-period unevenness are mixed can be formed, and a good haze ratio can be obtained. It was. However, a better haze ratio was obtained when a glass substrate containing the above metal was used.
  • the etching residue contains a reaction product with at least one oxide or fluorine of alkali metal, alkaline earth metal, magnesium and aluminum which are difficult to volatilize during etching, and this becomes a residue, It is considered that the effect of masking during etching can be obtained, and the effect of making the formation of various large and small irregularities with different irregularities more pronounced can be obtained.
  • Examples of the glass containing at least one of alkali metal, alkaline earth metal, magnesium, and aluminum include so-called soda glass, soda lime glass, and aluminosilicate glass.
  • borosilicate glass includes glass containing many of these elements.
  • MO X M: any one of Na, Ca, Mg, Al, and K
  • SiO 2 silicon dioxide
  • etching residues are only placed on the surface of the underlying glass substrate and can be easily removed by a water washing process. Moreover, removal can be performed more reliably by performing brush cleaning or cleaning using an acid.
  • FIG. 15 is a characteristic diagram showing the wavelength dependence of the haze ratio of a glass substrate with a transparent conductive film having an uneven structure formed by different methods.
  • FIG. 15 shows the relationship between the wavelength (nm) of light and the haze ratio (%) for a glass substrate with a transparent conductive film having surface irregularities formed by a different method.
  • plot E shows the experimental results (Example 4) in which a transparent conductive film mainly composed of zinc oxide (ZnO) was formed on the surface of the glass substrate on which irregularities were formed using HF gas as described above.
  • Plot F shows that the surface of the transparent conductive film is formed by wet etching after forming a transparent conductive film mainly composed of zinc oxide (ZnO) on the surface of a flat glass substrate on which unevenness is not formed.
  • the formed experimental results (Comparative Example 4) are shown.
  • Example 4 a haze ratio higher than that in Comparative Example 4 is realized in all wavelength ranges of 300 nm to 1500 nm based on the unevenness formed on the surface of the glass substrate.
  • the electrical characteristics are deteriorated by forming a thin film portion in the surface by etching, whereas in the case of Example 4, the transparent conductive film is roughened.
  • the transparent conductive film having a substantially uniform thickness covers the substrate, the electrical characteristics are also good. Therefore, according to Example 4, a transparent electrode having good optical characteristics and electrical characteristics can be realized.
  • a transparent electrode By forming a transparent electrode on a glass substrate having this surface texture structure, a good light scattering effect can be obtained at the interface between the irregularities of the glass substrate and the transparent electrode, and a good light confinement effect can be obtained.
  • a glass substrate with a transparent conductive film is obtained. Therefore, according to the present embodiment, it is possible to reduce the cost and improve the throughput, and it is possible to efficiently and inexpensively form a thin film solar cell having a light confinement structure that can provide a good light confinement effect.
  • the transparent electrode and the high performance of the solar cell using the transparent electrode have been described.
  • the glass substrate on which the unevenness is formed by the above-described method is used for the protective glass of the crystalline Si solar cell module, A confinement effect can be expected.
  • a crystalline Si solar cell is placed on the back side of a glass substrate on which irregularities are formed, and the back side is covered with a sealing member such as a sealing sheet.
  • the solar battery cell is sealed by being sandwiched between a glass substrate and a sealing member. Since there is a glass substrate with excellent light scattering characteristics on the light receiving surface side of the solar battery cell, the solar battery is excellent in light utilization efficiency.
  • a reflective metal such as silver can be formed on the glass substrate to provide a diffuse reflector with good wavelength characteristics.
  • an optical component in which a film that reflects light of a selective wavelength with a dielectric multilayer film can be formed.
  • an antireflection film may be formed on the uneven surface in order to improve the light transmittance.
  • FIG. 16 is sectional drawing which shows typically an example of the manufacturing process of the solar cell substrate concerning Embodiment 3.
  • FIG. 16 is sectional drawing which shows typically an example of the manufacturing process of the solar cell substrate concerning Embodiment 3.
  • FIG. 16 is sectional drawing which shows typically an example of the manufacturing process of the solar cell substrate concerning Embodiment 3.
  • FIG. 16 is sectional drawing which shows typically an example of the manufacturing process of the solar cell substrate concerning Embodiment 3.
  • FIG. 16A is sectional drawing which shows typically an example of the manufacturing process of the solar cell substrate concerning Embodiment 3.
  • FIG. 16A is sectional drawing which shows typically an example of the manufacturing process of the solar cell substrate concerning Embodiment 3.
  • FIG. 16A is sectional drawing which shows typically an example of the manufacturing process of the solar cell substrate concerning Embodiment 3.
  • FIG. 16A is sectional drawing which shows typically an example of the manufacturing process of the solar cell substrate concerning Embodiment 3.
  • FIG. 16A is sectional drawing which shows typically an example of the manufacturing process of
  • the light-transmitting insulating substrate 2 is sufficiently washed and dried so that moisture other than adsorbed moisture in the atmosphere, such as moisture accumulated at the bottom of the unevenness, is not attached to the substrate surface. Put it in a state. Then, this translucent insulating substrate 2 is etched using hydrogen fluoride gas under reduced pressure in the same manner as in the first embodiment, so that irregularities with a shorter period are formed on the slopes of the irregularities 8a formed by frosting. Additional processing is performed to form the unevenness 8b (FIG. 16B).
  • the unevenness 8b has a shape feature in which long-period unevenness and short-period unevenness are mixed as in the first and second embodiments.
  • the etching time at this time is shorter than that when forming irregularities with only hydrogen fluoride gas, and the etching time is adjusted according to the irregularity depth and period of the long-period irregularities 8a formed by frosting.
  • corrugated shape of this Embodiment obtained by carrying out AFM measurement on the translucent insulating substrate 2 concerning Embodiment 3 in which the unevenness
  • the depth distribution obtained by histogram analysis of the surface shape is distributed in the range of 0.75 ⁇ m to 0.9 ⁇ m, has a peak near 0.85 ⁇ m, and the half width of the peak is 0.03 ⁇ m or more. It has a certain distribution shape.
  • the frequency of the spatial frequency obtained by Fourier transform analysis of the surface shape of the translucent insulating substrate 2 according to the third embodiment in which the unevenness 8b is formed in this way is 1.0 ⁇ m or more and 1.2 ⁇ m or less. It has a peak b1 in the range, and the frequency a1 of 0.4 ⁇ m is not less than 1 ⁇ 4 and not more than 1 ⁇ 2 of the frequency of the peak existing in the range of 1.0 ⁇ m to 1.2 ⁇ m.
  • the half width of the peak of the depth distribution is 0.05 ⁇ m or more, the peak is a single peak, and the absolute value of the difference in depth corresponding to the two minimum values of the depth distribution.
  • the ratio of the absolute value of the difference between the depth indicating the peak of the depth distribution and the depth indicating the minimum value is 0.1 or more.
  • FIG. 17 is a diagram illustrating an example of the frequency of the spatial frequency obtained by performing Fourier transform analysis on the surface shape data of the glass texture formed by the glass texture method according to the third embodiment.
  • FIG. 18 is a diagram showing the frequency of the spatial frequency obtained by Fourier transform analysis of the surface shape data of two glass textures formed by the conventional glass texture method as a comparative example.
  • FIG. 18A used a sand blast method
  • FIG. 18B used a dry etching method.
  • FIG. 19 is a characteristic diagram showing a haze ratio between a solar cell substrate formed by the glass texture method according to the third embodiment and a solar cell substrate formed by a conventional glass texture method as a comparative example.
  • the plot G is the experimental result of the solar cell substrate according to the third embodiment having the spatial frequency frequency shown in FIG. 17, and the plot H is the conventional solar having the spatial frequency frequency shown in FIG.
  • the experimental results of the battery substrate, Plot I shows the experimental results of the conventional solar cell substrate having the frequency of the spatial frequency shown in FIG.
  • the solar cell substrate according to the third embodiment is a solar cell having a frequency of spatial frequency that deviates from the characteristics of the frequency of the spatial frequency of the surface of the translucent insulating substrate 2 according to the third embodiment. It can be seen that a significantly higher haze ratio is obtained at all wavelengths of 300 to 1500 nm than the battery substrate.
  • the transparent electrode layer 3 is formed by the method similar to Embodiment 1 (FIG.16 (c)).
  • the transparent electrode layer 3 is formed by the method similar to Embodiment 1 (FIG.16 (c)).
  • the rough surface (unevenness 8b) of the translucent insulating substrate 2 is reflected, and unevenness 3a similar to the translucent insulating substrate 2 is formed (FIG. 16D).
  • a thin film solar cell can be formed by the same method as in the first embodiment. In this case, the same effect as in the first embodiment can be obtained.
  • Embodiment 3 a light confinement structure capable of obtaining a good light confinement effect can be formed efficiently and inexpensively, and a solar cell excellent in electrical characteristics and optical characteristics can be obtained efficiently and inexpensively.
  • FIG. 20 is a cross-sectional view schematically illustrating an example of the manufacturing process of the solar cell substrate according to the fourth embodiment.
  • a cleaned translucent insulating substrate 2 is prepared in which dirt on the substrate surface is sufficiently removed by alkali cleaning or acid cleaning.
  • the surface of the translucent insulating substrate 2 is subjected to sand blasting to form long-period irregularities 9a (FIG. 20A).
  • the size of the abrasive grains used at that time is not particularly limited.
  • the period of the unevenness 9a becomes long, and when the size of the abrasive grains is small, the period of the unevenness 9a becomes short.
  • the spraying pressure is high, the light-transmitting insulating substrate 2 is damaged, the bending strength is weakened, and the reliability of the light-transmitting insulating substrate 2 is reduced. It is desirable to set the pressure low.
  • the translucent insulating substrate 2 is etched using hydrogen fluoride gas under reduced pressure in the same manner as in the second embodiment, so that irregularities with a shorter period are formed on the slopes of the irregularities 9a formed by the sandblasting process. Additional processing is performed to form the unevenness 9b (FIG. 20B). Thereby, the solar cell board
  • the unevenness 9b has a shape feature in which long-period unevenness and short-period unevenness are mixed as in the case of the first and second embodiments.
  • the transparent electrode layer 3 is formed by the method similar to Embodiment 1 (FIG.20 (c)).
  • the transparent electrode layer 3 is formed by the method similar to Embodiment 1 (FIG.20 (c)).
  • the rough surface (unevenness 9b) of the translucent insulating substrate 2 is reflected, and unevenness 3a similar to the translucent insulating substrate 2 is formed (FIG. 20D).
  • a thin film solar cell can be formed by the same method as in the first embodiment. In this case, the same effect as in the first embodiment can be obtained.
  • Embodiment 4 a light confinement structure capable of obtaining a good light confinement effect can be formed efficiently and inexpensively, and a solar cell excellent in electrical characteristics and optical characteristics can be obtained efficiently and inexpensively.
  • the method for forming a transparent electrode according to the present invention is useful for efficiently and inexpensively forming a concavo-convex shape capable of obtaining a good light confinement effect as a light confinement structure used in a solar cell on a glass substrate. is there.
  • Thin film solar cell module (module), 2. Translucent insulating substrate, 2a, 3a unevenness, 3. Transparent electrode layer, 4, 6, 41, 42 Photoelectric conversion layer, 4a, 6a, 41a, 42a p-type semiconductor layer, 4b , 6b, 41b, 42b i-type semiconductor layer, 4c, 6c, 41c, 42c n-type semiconductor layer, 5 intermediate layer, 7 back electrode layer, 8a, 8b unevenness, 9a, 9b unevenness, 21 decompression vessel, 22-1 mass flow Controller, 22-2 mass flow controller, 23 shower head, 24-1 supply piping, 24-2 supply piping, 25 vacuum pump, 26 exhaust piping, C cell, D1 first groove, D2 second groove, D3 third Groove.

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  • Photovoltaic Devices (AREA)

Abstract

L'invention porte sur un substrat de cellule solaire comprenant un matériau isolant transparent ayant des irrégularités formées sur la surface. La distribution de profondeur obtenue par réalisation d'une analyse d'histogramme sur le profil de la surface sur laquelle les irrégularités sont formées est distribuée dans une plage de 0,75 ́m à 0,9 ́m, présente un pic près de 0,85 µm, et possède un profil de distribution dans lequel la largeur à mi-hauteur du pic est supérieure ou égale à 0,03 µm. Il est ainsi possible de former, à un rendement stable, une couche d'électrode transparente dans laquelle un fort effet de diffusion sur la lumière allant d'une région de lumière visible à basse fréquence à une région de longueur d'onde proche de l'infrarouge est obtenu et dans laquelle toute diminution d'électro-conductivité peut être réduite au minimum.
PCT/JP2012/070648 2011-09-29 2012-08-13 Substrat de cellule solaire et son procédé de fabrication, cellule solaire à couches minces et son procédé de fabrication, procédé de fabrication de substrat isolant transmettant la lumière portant une électrode transparente Ceased WO2013046968A1 (fr)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111900219A (zh) * 2020-07-10 2020-11-06 唐山科莱鼎光电科技有限公司 用于制备薄膜太阳能电池第一道刻线、第三道刻线的方法
US20230317868A1 (en) * 2022-01-24 2023-10-05 Contemporary Amperex Technology Co., Limited Solar cell and method for preparing same, photovoltaic module and power consuming device
CN120529700A (zh) * 2025-07-21 2025-08-22 晶科能源(海宁)有限公司 光伏电池及其制造方法、叠层电池、光伏组件

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001015782A (ja) * 1999-06-29 2001-01-19 Kyocera Corp 太陽電池素子およびその製造方法
JP2003060216A (ja) * 2001-08-10 2003-02-28 Nippon Sheet Glass Co Ltd 光電変換装置用基板
WO2003036657A1 (fr) * 2001-10-19 2003-05-01 Asahi Glass Company, Limited Substrat a couche d'oxyde conductrice transparente, son procede de production et element de conversion photoelectrique

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001015782A (ja) * 1999-06-29 2001-01-19 Kyocera Corp 太陽電池素子およびその製造方法
JP2003060216A (ja) * 2001-08-10 2003-02-28 Nippon Sheet Glass Co Ltd 光電変換装置用基板
WO2003036657A1 (fr) * 2001-10-19 2003-05-01 Asahi Glass Company, Limited Substrat a couche d'oxyde conductrice transparente, son procede de production et element de conversion photoelectrique

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111900219A (zh) * 2020-07-10 2020-11-06 唐山科莱鼎光电科技有限公司 用于制备薄膜太阳能电池第一道刻线、第三道刻线的方法
US20230317868A1 (en) * 2022-01-24 2023-10-05 Contemporary Amperex Technology Co., Limited Solar cell and method for preparing same, photovoltaic module and power consuming device
CN120529700A (zh) * 2025-07-21 2025-08-22 晶科能源(海宁)有限公司 光伏电池及其制造方法、叠层电池、光伏组件

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