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WO2013161145A1 - Cellule solaire liée côté arrière et son procédé de fabrication - Google Patents

Cellule solaire liée côté arrière et son procédé de fabrication Download PDF

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Publication number
WO2013161145A1
WO2013161145A1 PCT/JP2013/000916 JP2013000916W WO2013161145A1 WO 2013161145 A1 WO2013161145 A1 WO 2013161145A1 JP 2013000916 W JP2013000916 W JP 2013000916W WO 2013161145 A1 WO2013161145 A1 WO 2013161145A1
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Prior art keywords
layer
conductivity type
solar cell
contact region
back junction
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English (en)
Japanese (ja)
Inventor
亘 篠原
運也 本間
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Panasonic Corp
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Panasonic Corp
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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
    • 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
    • H10F77/219—Arrangements for electrodes of back-contact 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
    • H10F10/10—Individual photovoltaic cells, e.g. solar cells having potential barriers
    • H10F10/14—Photovoltaic cells having only PN homojunction potential barriers
    • H10F10/146—Back-junction photovoltaic cells, e.g. having interdigitated base-emitter regions on the back side
    • 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
    • H10F10/164—Photovoltaic cells having only PN heterojunction potential barriers comprising heterojunctions with Group IV materials, e.g. ITO/Si or GaAs/SiGe photovoltaic cells
    • H10F10/165—Photovoltaic cells having only PN heterojunction potential barriers comprising heterojunctions with Group IV materials, e.g. ITO/Si or GaAs/SiGe photovoltaic cells the heterojunctions being Group IV-IV heterojunctions, e.g. Si/Ge, SiGe/Si or Si/SiC photovoltaic cells
    • H10F10/166—Photovoltaic cells having only PN heterojunction potential barriers comprising heterojunctions with Group IV materials, e.g. ITO/Si or GaAs/SiGe photovoltaic cells the heterojunctions being Group IV-IV heterojunctions, e.g. Si/Ge, SiGe/Si or Si/SiC photovoltaic cells the Group IV-IV heterojunctions being heterojunctions of crystalline and amorphous materials, e.g. silicon heterojunction [SHJ] 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
    • H10F77/00—Constructional details of devices covered by this subclass
    • H10F77/10—Semiconductor bodies
    • H10F77/14—Shape of semiconductor bodies; Shapes, relative sizes or dispositions of semiconductor regions within semiconductor bodies
    • H10F77/148—Shapes of potential barriers
    • 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
    • Y02E10/547—Monocrystalline silicon PV cells

Definitions

  • the present invention relates to a back junction solar cell and a manufacturing method thereof.
  • Patent Document 1 a back junction solar cell in which a single crystal doping layer is homojunctioned to a single crystal silicon substrate on the back surface side is disclosed.
  • An object of the present invention is to provide a back junction solar cell that suppresses efficiency reduction due to recombination and a method for manufacturing the back junction solar cell.
  • One aspect of the present invention is a back junction solar cell having a first conductivity type contact region and a second conductivity type contact region on a main surface opposite to a light incident surface, the first conductivity type contact region Is a region where the crystalline base layer and the crystalline first conductivity type layer or the first conductivity type diffusion layer are homojunction, and the second conductivity type contact region is the base layer and the amorphous i-type
  • the back junction solar cell is a region where the layer and the second conductivity type layer are heterojunctioned.
  • a crystalline first conductivity type layer or a first conductivity type diffusion layer is formed on a main surface opposite to a light incident surface in a base layer of a crystalline semiconductor layer serving as a power generation layer.
  • the present invention it is possible to provide a back junction solar cell that suppresses a decrease in efficiency due to recombination and a method for manufacturing the same.
  • the solar cell 100 in the first embodiment includes a substrate 18, a passivation layer 16, a base layer 14, a first conductivity type layer 12, an insulating layer 20, an i-type layer 22, A two-conductivity type layer 24, a transparent electrode layer 26, and a metal layer 28 (first electrode 28n, second electrode 28p) are included.
  • Solar cell 100 in the present embodiment is a back junction solar cell, and an electrode for taking out the electric power generated by the solar cell to the outside is provided only on the main surface (hereinafter referred to as the back surface) opposite to the light receiving surface. .
  • the light receiving surface means a main surface on which light is mainly incident in the solar cell, and specifically, a surface on which most of the light incident on the solar cell is incident.
  • a back surface means the surface on the opposite side to the light-receiving surface of a solar cell.
  • the substrate 18 mechanically supports the solar cell and protects the semiconductor layer included in the solar cell from the external environment. Further, since the substrate 18 is arranged on the light receiving surface side of the solar cell, the substrate 18 is a material that can transmit light in a wavelength band used for power generation in the solar cell and mechanically support each layer such as the base layer 14. .
  • the substrate 18 may be a light-transmitting glass or plastic.
  • the base layer 14 is a crystalline semiconductor layer.
  • the base layer 14 becomes a power generation layer of the solar cell.
  • the base layer 14 is an n-type crystalline silicon layer to which an n-type dopant is added.
  • the doping concentration of the base layer 14 may be about 10 16 / cm 3 .
  • the film thickness of the base layer 14 is preferably a film thickness that can sufficiently generate carriers as the power generation layer, and may be, for example, 1 ⁇ m or more and 100 ⁇ m or less.
  • the crystalline includes not only a single crystal but also a polycrystal in which a large number of crystal grains are aggregated.
  • the passivation layer 16 is provided between the substrate 18 and the base layer 14.
  • the passivation layer 16 plays a role of terminating dangling bonds (dangling bonds) on the surface of the base layer 14 and suppresses carrier recombination on the surface of the base layer 14.
  • dangling bonds dangling bonds
  • the passivation layer 16 may include, for example, a silicon nitride layer (SiN), and more preferably has a stacked structure of a silicon oxide layer (SiOx) and silicon nitride.
  • SiN silicon nitride layer
  • SiOx silicon oxide layer
  • silicon nitride a structure in which a silicon oxide layer and a silicon nitride layer are sequentially stacked with a thickness of 30 nm and 40 nm, respectively, may be used.
  • the first conductivity type layer 12 is a crystalline semiconductor layer.
  • the first conductivity type layer 12 is an n-type crystalline silicon layer to which an n-type dopant is added.
  • the first conductivity type layer 12 is a layer bonded to the metal layer 28 (first electrode 28 n), and has a higher doping concentration than the base layer 14.
  • the doping concentration of the first conductivity type layer 12 may be about 10 19 / cm 3 .
  • the film thickness of the first conductivity type layer 12 is preferably as thin as possible within a range where the contact resistance with the metal can be sufficiently lowered, and may be, for example, 0.1 ⁇ m or more and 2 ⁇ m or less.
  • the base layer 14 and the first conductivity type layer 12 form a first conductivity type contact region C1 in which the crystalline materials are homo-joined.
  • the first conductivity type contact region C ⁇ b> 1 is formed in a comb shape including fingers and bus bars in the surface of the solar cell 100, for example.
  • the area of the first conductivity type contact region C ⁇ b> 1 means the area of a region that is homojunction with the first conductivity type layer 12 on the main surface of the base layer 14.
  • the insulating layer 20 is used to electrically insulate the first conductivity type layer 12 from an i-type layer 22 and a second conductivity type layer 24 described later, and a mask for etching the first conductivity type layer 12.
  • Used as The insulating layer 20 is made of an electrically insulating material, for example, silicon nitride (SiN).
  • the thickness of the insulating layer 20 may be about 100 nm, for example.
  • the i-type layer 22 and the second conductivity type layer 24 are amorphous semiconductor layers. Note that the amorphous system includes an amorphous phase or a microcrystalline phase in which minute crystal grains are precipitated in the amorphous phase.
  • the i-type layer 22 and the second conductivity type layer 24 are made of amorphous silicon containing hydrogen.
  • the i-type layer 22 is a substantially intrinsic amorphous silicon layer.
  • the second conductivity type layer 24 is an amorphous silicon layer to which a p-type dopant is added.
  • the second conductivity type layer 24 is a semiconductor layer having a higher doping concentration than the i-type layer 22.
  • the i-type layer 22 is not intentionally doped, and the doping concentration of the second conductivity type layer 24 may be about 10 18 / cm 3 .
  • the thickness of the i-type layer 22 is made thin so that light absorption can be suppressed as much as possible, while it is made thick enough that the surface of the base layer 14 is sufficiently passivated. Specifically, the thickness may be 1 nm or more and 50 nm or less, for example, 10 nm.
  • the film thickness of the second conductivity type layer 24 is made thin so that light absorption can be suppressed as much as possible, while it is made so thick that the open circuit voltage of the solar cell becomes sufficiently high. For example, the thickness may be 1 nm or more and 50 nm or less, for example, 10 nm.
  • the transparent electrode layer 26 is doped with tin oxide (SnO 2 ), zinc oxide (ZnO), indium tin oxide (ITO), etc. with tin (Sn), antimony (Sb), fluorine (F), aluminum (Al), etc. It is preferable to use at least one or a combination of a plurality of transparent conductive oxides (TCO).
  • TCO transparent conductive oxides
  • ZnO zinc oxide
  • the film thickness of the transparent electrode layer 26 may be 10 nm or more and 500 nm or less, for example, 100 nm.
  • the base layer 14, the i-type layer 22, and the second conductivity type layer 24 form a second conductivity type contact region C2 in which crystalline and amorphous are heterojunctioned.
  • the second conductivity type contact region C2 includes, for example, fingers and bus bars on the surface of the solar cell 100, and is formed in a comb shape combined with the first conductivity type contact region C1.
  • the area of the second conductivity type contact region C ⁇ b> 2 means the area of a region heterojunction with the i-type layer 22 and the second conductivity type layer 24 on the main surface of the base layer 14.
  • the metal layer 28 is a layer serving as an electrode provided on the back side of the solar cell.
  • the metal layer 28 is made of a conductive material such as metal, and is made of a material containing, for example, copper (Cu) or aluminum (Al).
  • the metal layer 28 includes a first electrode 28 n connected to the first conductivity type layer 12 and a second electrode 28 p connected to the second conductivity type layer 24.
  • the metal layer 28 may further include an electrolytic plating layer such as copper (Cu) or tin (Sn). However, it is not limited to this, It is good also as other metals, such as gold
  • 2A to 2J show a method for manufacturing solar cell 100 in the first embodiment.
  • the substrate 10 is made of a crystalline semiconductor material.
  • a semiconductor substrate such as silicon, polycrystalline silicon, gallium arsenide (GaAs), or indium phosphide (InP) is used.
  • the substrate 10 may be made of a material other than silicon, and these layers may be made of materials other than the silicon layer.
  • a porous layer 10a is formed on one main surface of the substrate 10 (FIG. 2A).
  • the porous layer 10a can be formed by anodic oxidation or the like.
  • the electrolyte used for anodization can be, for example, a mixed liquid of hydrofluoric acid and ethanol, or a mixed liquid of hydrofluoric acid and hydrogen peroxide.
  • the current density of the anodic oxidation may be 5 mA / cm 2 or more and 600 nA / cm 2 or less, for example, about 10 mA / cm 2 .
  • the thickness of the porous layer 10a may be 0.01 ⁇ m or more and 30 ⁇ m or less, for example, about 10 ⁇ m.
  • the pore diameter of the porous layer 10a may be 0.002 ⁇ m or more and 5 ⁇ m or less, for example, about 0.01 ⁇ m.
  • the porosity of the porous layer 10a may be 10% or more and 70% or less, for example, about 20%.
  • a first conductivity type layer 12 and a base layer 14 are formed on the porous layer 10a of the substrate 10 (FIG. 2B).
  • the first conductivity type layer 12 and the base layer 14 can be formed by chemical vapor deposition (CVD).
  • the first conductivity type layer 12 and the base layer 14 are formed by epitaxial growth using the porous layer 10a as a seed layer, and form a homojunction region in which crystalline semiconductor layers are joined to each other.
  • the film can be formed by heating the substrate 10 to 950 ° C. and supplying dichlorosilane (SiH 2 Cl 2 ) diluted with hydrogen (H 2 ) as a source gas.
  • the flow rates of hydrogen (H 2 ) and dichlorosilane (SiH 2 Cl 2 ) are, for example, 0.5 (l / min) and 180 (l / min), respectively. Further, if necessary, phosphine (PH 3 ) is added as a doping gas.
  • a passivation layer 16 is formed on the base layer 14 (FIG. 2C).
  • the passivation layer 16 can be formed by plasma enhanced chemical vapor deposition (PECVD) in which a raw material gas obtained by mixing oxygen (O 2 ) or nitrogen (N 2 ) with silane (SiH 4 ) is supplied as a plasma.
  • PECVD plasma enhanced chemical vapor deposition
  • the substrate 18 is bonded to the passivation layer 16 (FIG. 2D).
  • the substrate 18 is bonded to the passivation layer 16 with an adhesive or the like.
  • the adhesive is a material that transmits light in a wavelength band used for power generation in a solar cell.
  • FIGS. 2A to 2C are shown upside down from FIGS. 2A to 2C for easy understanding.
  • the solar cell may be modularized by bonding a plurality of substrates 10 to the substrate 18.
  • FIG. 3 shows an example in which 24 substrates 10 are bonded to one substrate 18 to form a module.
  • the substrate 10 is separated using the porous layer 10a (FIG. 2E).
  • the substrate 10 can be separated by mechanical processing.
  • the substrate 10 can be separated from the porous layer 10a portion by adsorbing the substrate 10 and the substrate 18 with a vacuum chuck and pulling the substrate 10 and the substrate 18 apart.
  • the substrate 10 can be separated from the porous layer 10a portion. If a part of the porous layer 10a remains on the first conductivity type layer 12 side, the first layer is etched by hydrofluoric acid mixed with hydrofluoric acid (HF) and nitric acid (HNO 3 ).
  • the porous layer 10a on the conductive type layer 12 may be removed.
  • the insulating layer 20 is formed on the first conductivity type layer 12, and the first conductivity type layer 12 is patterned (FIG. 2F).
  • the insulating layer 20 can be formed by plasma enhanced chemical vapor deposition (PECVD) in which a raw material gas in which nitrogen (N 2 ) is mixed with silane (SiH 4 ) is supplied in a plasma state.
  • PECVD plasma enhanced chemical vapor deposition
  • Patterning can be performed using an etching paste.
  • the first conductive type layer 12 is removed together with the insulating layer 20 by applying an etching paste containing phosphoric acid in a desired pattern by a screen printing method or the like.
  • the insulating layer 20 may be removed by dry etching so that a desired pattern is obtained, and the first conductivity type layer 12 may be removed by dry etching or wet etching using the insulating layer 20 as a mask.
  • RIE reactive ion etching
  • CF 4 carbon tetrafluoride
  • RIE reactive ion etching
  • SF 6 sulfur hexafluoride
  • An etchant containing hydrofluoric acid may be used for wet etching of the first conductivity type layer 12.
  • the insulating layer 20 and the first conductivity type layer 12 are preferably patterned so that power can be collected as evenly as possible from the back surface of the solar cell.
  • a comb-shaped pattern including fingers and bus bars that are generally applied to solar cells is preferable.
  • An i-type layer 22, a second conductivity type layer 24, and a transparent electrode layer 26 are formed on the base layer 14 and the insulating layer 20 exposed by patterning (FIG. 2G).
  • the i-type layer 22 and the second conductivity type layer 24 can be formed by PECVD of a silicon-containing gas such as silane (SiH 4 ). While supplying a silicon-containing gas such as silane (SiH 4 ) and supplying a high-frequency power from a high-frequency power source to a high-frequency electrode, plasma of the source gas is generated, and the source material is supplied from the plasma onto the base layer 14 and the insulating layer 20. Thus, a silicon thin film is formed.
  • the source gas is mixed with a dopant-containing gas such as boron (B 2 H 6 ) as necessary.
  • the transparent electrode layer 26 can be formed using a sputtering method or the like.
  • the i-type layer 22, the second conductivity type layer 24, the transparent electrode layer 26, and the insulating layer 20 formed on the entire surface are patterned (FIG. 2H). Patterning can be performed using an etching paste.
  • the i-type layer 22, the second conductivity type layer 24, the transparent electrode layer 26, and the insulating layer 20 are removed by applying an etching paste containing phosphoric acid in a desired pattern by a screen printing method or the like.
  • the layer 22, the second conductivity type layer 24, the transparent electrode layer 26, and the insulating layer 20 are removed and patterned.
  • the pattern is set so that power can be collected as evenly as possible from the back surface of the solar cell.
  • a comb pattern that is alternately combined with the comb pattern of the first conductivity type layer 12 is preferable.
  • a metal layer 28 is formed on the patterned surface (FIG. 2I).
  • the metal layer 28 can be formed by a thin film formation method such as sputtering or plasma enhanced chemical vapor deposition (PECVD).
  • PECVD plasma enhanced chemical vapor deposition
  • the i-type layer 22, the second conductivity type layer 24, the transparent electrode layer 26 and the metal layer 28 are partially removed (FIG. 2J). Thereby, the metal layer 28 is divided, and the first electrode 28 n connected to the first conductivity type layer 12 and the second electrode 28 p connected to the transparent electrode layer 26 are formed.
  • the i-type layer 22, the second conductivity type layer 24, the transparent electrode layer 26, and the metal layer 28 can be removed by laser etching. Also, a resist mask is applied by screen printing or the like to form a patterned mask, and the i-type layer 22, the second conductivity type layer 24, the transparent electrode layer 26, and the metal layer 28 are separately etched using the mask. May be. If the metal layer 28 is copper (Cu), ferric chloride may be used as an etchant, and if the metal layer 28 is aluminum (Al), phosphoric acid may be used as an etchant. For etching the transparent electrode layer 26, an etchant containing hydrochloric acid (HCl) may be used. An etchant containing hydrofluoric acid (HF) may be used for etching the i-type layer 22 and the second conductivity type layer 24.
  • Cu copper
  • ferric chloride may be used as an etchant
  • Al aluminum
  • phosphoric acid may be used as an etchant.
  • HCl hydro
  • the i-type layer 22 and the second conductive layer are connected so that the first electrode 28n connected to the first conductive type layer 12 and the second electrode 28p connected to the second conductive type layer 24 are electrically separated.
  • the mold layer 24, the transparent electrode layer 26, and the metal layer 28 are removed.
  • the i-type layer 22, the second conductivity-type layer 24, the transparent electrode layer 26, and the metal layer 28 on the region of the insulating layer 20 left on the first conductivity-type layer 12 are removed.
  • a metal layer may be further laminated on the first electrode 28n and the second electrode 28p by electrolytic plating or the like.
  • electrolytic plating For example, copper (Cu) or tin (Sn) is formed by electrolytic plating.
  • Cu copper
  • Sn tin
  • the metal layer is laminated only on the region where the first electrode 28n and the second electrode 28p are left.
  • solar cell 100 in the present embodiment is formed (FIG. 2J).
  • the substrate 18 is on the light receiving surface side
  • the first electrode 28n and the second electrode 28p are both a back surface junction type provided on the back surface side.
  • the first electrode 28n and the second electrode 28p of the plurality of solar cells arranged in parallel are connected by a conductive tab, and the plurality of solar cells are connected in series or in parallel.
  • coat a filler to the back surface side of a solar cell and you may seal with a sealing material.
  • the filler and the sealing material can be resin materials such as EVA and polyimide. This can prevent moisture from entering the power generation layer of the solar cell module.
  • the sealing material can be the same glass or plastic transparent substrate as the substrate 10. Thereby, the intensity
  • a reflective layer may be provided between the filler and the transparent substrate, or the sealing material itself may be a colored substrate.
  • first conductivity type layer 12 is epitaxially grown on base layer 14 to form first conductivity type contact region C1 that is a homojunction between crystalline materials.
  • the second conductivity type layer 24 forms a second conductivity type contact region C2 which is a heterojunction between the base layer 14 and crystalline and amorphous.
  • passivation is sufficient at the junction interface, and loss of carriers due to recombination can be suppressed. Thereby, the power generation efficiency of the solar cell 100 can be improved.
  • the porous layer 10a may be left on the first conductivity type layer 12.
  • the porous layer 10a since the porous layer 10a remains between the first conductivity type layer 12 and the insulating layer 20 with the surface being uneven, the light reaching the porous layer 10a out of the light incident from the substrate 18 side is diffusely reflected. To return to the base layer 14.
  • the solar cell 102 in the second embodiment includes a substrate 18, a passivation layer 16, a base layer 14, a first conductivity type layer 12, an insulating layer 20, an i-type layer 22, A two-conductivity type layer 24, a transparent electrode layer 26, and a metal layer 28 (first electrode 28n, second electrode 28p) are included.
  • This embodiment is different from the solar cell 100 in the first embodiment in that an undercut A (gap) is provided between the first conductivity type layer 12 and the i-type layer 22 and the second conductivity type layer 24. . Since other components are the same as those of the solar cell 100 in the first embodiment, description thereof is omitted. Hereinafter, the undercut A will be described together with the manufacturing method.
  • the first conductivity type layer 12 is also etched in the plane direction of the substrate 18 to form an undercut A (FIG. 5A).
  • the undercut A is a space formed under the patterned insulating layer 20.
  • the undercut A can be formed by subjecting the first conductivity type layer 12 to isotropic etching.
  • hydrofluoric acid obtained by mixing hydrofluoric acid (HF) and nitric acid (HNO 3 ) may be used.
  • the undercut A functions as a gap (space) that prevents the i-type layer 22 and the second conductivity type layer 24 from being in direct contact with the first conductivity type layer 12 (FIG. 5B).
  • the processing is performed up to the patterning of the metal layer 28 (FIGS. 5C to 5E). Thereby, the solar cell 102 is formed.
  • the i-type layer 22 and the second conductivity type layer 24 are not in direct contact with the first conductivity type layer 12 by providing a gap (undercut A) that is a space in which nothing is filled. Therefore, current leakage between the i-type layer 22 and the second conductivity type layer 24 and the first conductivity type layer 12 is suppressed, and the power generation efficiency of the solar cell 102 is improved.
  • the solar cell 104 in the third embodiment includes a substrate 18, a passivation layer 16, a base layer 14, a first conductivity type diffusion layer 42, an i-type layer 22, and a second conductivity type.
  • the layer 24 includes the transparent electrode layer 26 and the metal layer 44 (first electrode 44n, second electrode 44p).
  • Solar cell 104 in the present embodiment is a back junction solar cell, and an electrode for taking out the electric power generated by the solar cell to the outside is provided only on the main surface (hereinafter referred to as the back surface) opposite to the light receiving surface. .
  • the first conductivity type layer 12, the insulating layer 20, and the metal layer 28 are not provided, but the first conductivity type diffusion layer 42 and the metal layer 44 are provided. Since it is different from the solar cell 100 in the embodiment, these will be described in detail, and description of similar components will be omitted.
  • the first conductivity type diffusion layer 42 is a layer obtained by diffusing a first conductivity type (n-type) dopant in the base layer 14.
  • the first conductivity type diffusion layer 42 is provided in a region where the i-type layer 22, the second conductivity type layer 24, and the transparent electrode layer 26 are not formed.
  • the doping concentration of the first conductivity type diffusion layer 42 may be about 10 19 / cm 3 .
  • the base layer 14 and the first conductivity type diffusion layer 42 form a first conductivity type contact region C1 in which crystals are homo-joined.
  • the first conductivity type contact region C ⁇ b> 1 is formed in a comb shape including fingers and bus bars on the surface of the solar cell 104, for example.
  • the area of the first conductivity type contact region C ⁇ b> 1 means the area of a region that is homojunction with the first conductivity type diffusion layer 42 in the main surface of the base layer 14.
  • the pattern width of the first conductivity type diffusion layer 42 is 1.6 mm
  • the pattern width of the second conductivity type layer 24 is May be set to 2.0 mm, and a region in which the base layer 14 of 0.2 mm is left between the two may be provided.
  • the metal layer 44 is a layer serving as an electrode provided on the back side of the solar cell. Similarly to the metal layer 28, the metal layer 44 is made of a conductive material such as metal, and is made of, for example, a material containing copper (Cu) or aluminum (Al).
  • the metal layer 44 includes a first electrode 44 n connected to the first conductivity type diffusion layer 42 and a second electrode 44 p connected to the second conductivity type layer 24.
  • the metal layer 44 may further include an electrolytic plating layer such as copper (Cu) or tin (Sn). However, it is not limited to this, It is good also as other metals, such as gold
  • 7A to 7L show a method for manufacturing the solar cell 104 according to the third embodiment.
  • the substrate 10 is made of a crystalline semiconductor material as in the first embodiment.
  • a porous layer 10a is formed on the substrate 10 (FIG. 7A).
  • a base layer 14 is formed on the porous layer 10a (FIG. 7B).
  • the first conductivity type layer 12 is not formed.
  • a passivation layer 16 is formed on the base layer 14 (FIG. 7C). The formation method of the base layer 14 and the passivation layer 16 may be the same as that in the first embodiment.
  • the passivation layer 16 is bonded to the substrate 18 (FIG. 7D). Then, the substrate 10 is separated using the porous layer 10a (FIG. 7E). These processes can also be performed as in the first embodiment.
  • An i-type layer 22, a second conductivity type layer 24, and a transparent electrode layer 26 are formed on the base layer 14 separated from the substrate 10 (FIG. 7F).
  • the i-type layer 22, the second conductivity type layer 24, and the transparent electrode layer 26 can be formed in the same manner as in the first embodiment except that they are formed on the entire surface of the base layer 14. That is, the i-type layer 22 and the second conductivity type layer 24 may be amorphous semiconductor layers, and the transparent electrode layer 26 may be a transparent conductive oxide (TCO) such as tin oxide (SnO 2 ).
  • TCO transparent conductive oxide
  • SnO 2 tin oxide
  • the i-type layer 22, the second conductivity type layer 24, and the transparent electrode layer 26 are patterned. Patterning can be performed using an etching paste, as in the first embodiment.
  • the i-type layer 22, the second conductivity type layer 24, and the transparent electrode layer 26 may be patterned so that power can be collected as evenly as possible from the back surface of the solar cell. For example, it is preferable to use a comb pattern as in the first embodiment.
  • a doped layer 40 containing an n-type dopant is formed on the patterned transparent electrode layer 26 and the exposed base layer 14 (FIG. 7H).
  • the doped layer 40 is used for diffusing an n-type dopant in the base layer 14.
  • the doped layer 40 can be, for example, an amorphous silicon layer containing n-type dopant, phosphosilicate glass (PSG), or the like.
  • the amorphous silicon layer can be formed by atmospheric pressure CVD or the like, and PSG can be formed by a coating method or the like.
  • the thickness of the doped layer 40 is preferably about 300 nm, for example.
  • the first conductivity type diffusion layer 42 is formed by the diffusion treatment of the dopant into the base layer 14 (FIG. 7I).
  • a process is performed in which diffusion is performed only in a region where the i-type layer 22, the second conductivity type layer 24, and the transparent electrode layer 26 are removed, that is, a region where the doped layer 40 is in direct contact with the base layer 14.
  • the first conductivity type diffusion layer 42 can be formed by irradiating only the target region with the laser beam B and diffusing the dopant into the base layer 14 by local heating with the laser beam B.
  • the laser beam B may have a wavelength of 532 nm, a power of 0.89 W, and a scanning speed of 50 mm / s.
  • the unnecessary doped layer 40 is removed by etching (FIG. 7J).
  • the doped layer 40 can be removed by, for example, nitrogen trifluoride (NF 3 ) plasma etching.
  • NF 3 nitrogen trifluoride
  • a metal layer 44 is formed on the patterned transparent electrode layer 26 and the exposed base layer 14 (FIG. 7K). The metal layer 44 can be formed in the same manner as in the first embodiment.
  • the metal layer 44 is removed, the metal layer 44 is divided, and the first electrode 44 n connected to the first conductivity type diffusion layer 42 and the second electrode 44 p connected to the transparent electrode layer 26. Are formed (FIG. 7L). Similar to the first embodiment, the metal layer 44 can be removed by laser etching or chemical etching.
  • the solar cell 104 in the present embodiment is formed.
  • the first conductivity type diffusion layer 42 diffuses a dopant into the base layer 14 to form a first conductivity type contact region C 1 that is a homojunction, but the i type layer 22 and the second conductivity type layer 24.
  • Forms a second conductivity type contact region C2 which is a heterojunction between the base layer 14 and crystalline and amorphous.
  • passivation is sufficient at the junction interface, and loss of carriers due to recombination can be suppressed. Thereby, the power generation efficiency of the solar cell 104 can be improved.
  • the low-concentration base layer 14 is left between the first conductivity type diffusion layer 42 and the second conductivity type layer 24, so that the gap between the first conductivity type diffusion layer 42 and the second conductivity type layer 24 is maintained. Current leakage is suppressed, and the power generation efficiency of the solar cell 102 is improved.
  • the base layer 14 is formed using the porous layer 10a formed on the substrate 10, and the base layer 14 is separated from the substrate 10 for use.
  • the scope of application of the present invention is not limited to this.
  • a back junction solar cell in which a first conductivity type contact region having a homojunction and a second conductivity type contact region having a hetero junction are formed on a single crystal substrate may be used.
  • the modification of the solar cell 104 in the third embodiment is configured to further include a passivation layer 50 as shown in the cross-sectional view of FIG.
  • the passivation layer 50 is provided between the first conductivity type diffusion layer 42 and the metal layer 44, and has a structure in which the generated current is taken out from the opening 50a provided in the passivation layer 50 to the first electrode 44n and the second electrode 44p. ing.
  • the solar cell 104 in this modification is formed in the same manner as in the third embodiment up to the step of FIG. 7J. Thereafter, a plasma of a raw material gas in which silane (SiH 4 ), hydrogen (H 2 ) and ammonia gas (NH 3 ) or silane (SiH 4 ), hydrogen (H 2 ), and nitrogen (N 2 ) are mixed is formed on the base layer 14.
  • a passivation layer 50 is formed by plasma enhanced chemical vapor deposition (PECVD) supplied (FIG. 9A). Thereby, the main component of the passivation layer 50 is silicon nitride (SiN).
  • the passivation layer 50 is not limited to silicon nitride (SiN), but may be hydrogenated amorphous silicon (a-Si: H) or amorphous silicon oxide (a-SiO 2 ) by a thermal CVD method.
  • the passivation layer 50 may be of a thickness that provides an effect of reducing carrier recombination.
  • the passivation layer 50 preferably has a thickness of several nm to 20 nm.
  • an opening 50a is formed in the passivation layer 50 (FIG. 9B).
  • the opening 50a can be formed by laser irradiation.
  • An opening 50a can be formed by irradiating a corresponding portion of the passivation layer 50 with a laser B2 having a wavelength of 355 nm (Nd: YAG laser beam third harmonic).
  • the laser B2 irradiation conditions are preferably an average power of 0.12 to 0.20 W, an oscillation frequency of 60 to 100 kHz, and a scanning speed of 700 to 1000 mm / s.
  • the i-type layer 22, the second conductivity type layer 24, and the transparent electrode layer 26 are not damaged significantly on the transparent electrode layer 26 and the first conductivity type diffusion layer 42.
  • the passivation layer 50 can be completely removed. Thereby, electrical contact between the first conductivity type diffusion layer 42 and the first electrode 44n and between the transparent electrode layer 26 and the second electrode 44p can be satisfactorily realized.
  • the opening 50a may be formed so that at least a part of the region between the first conductivity type diffusion layer 42 and the first electrode 44n is passivated by the passivation layer 50.
  • an opening 50 a having a width of 5 ⁇ m may be formed along the first conductivity type diffusion layer 42.
  • the passivation layer 50 between the transparent electrode layer 26 and the second electrode 44p may not be left.
  • the metal layer 44 is formed (FIG. 9C), and the first electrode 44n and the second electrode 44p are formed by removing a part of the metal layer 44 (FIG. 9). 9D).
  • the passivation layer 50 plays a role of terminating dangling bonds (dangling bonds) at the interface between the first conductivity type diffusion layer 42 and the first electrode 44n, which are homojunctions, and recombines carriers at this interface. Reduce losses due to By forming the passivation layer 50, the lifetime of the carrier is improved several times to 10 times or more, and as a result, the open circuit voltage Voc of the solar cell 104 is increased by about 1.1 times to 1.2 times.
  • Table 1 shows the open circuit voltage Voc, the short-circuit current Isc, and the curve factor F.E. when annealing is performed at an annealing temperature of 100 ° C., 150 ° C., and 200 ° C. for about 1 hour. F. And the power generation efficiency Pmax.
  • the value normalized with respect to other conditions is shown with the power generation efficiency Pmax being 1.

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  • Photovoltaic Devices (AREA)

Abstract

La présente invention concerne une cellule solaire liée côté arrière comportant une région de contact d'un premier type de conductivité et une région de contact d'un second type de conductivité sur la surface principale sur le côté opposé de la surface d'incidence de la lumière, la région de contact du premier type de conductivité étant une région d'homojonction entre une couche de base cristalline et une couche du premier type de conductivité cristalline, et la région de contact du second type de conductivité étant une région d'hétérojonction entre une couche de base, une couche amorphe du type i, et une couche du second type de conductivité.
PCT/JP2013/000916 2012-04-27 2013-02-19 Cellule solaire liée côté arrière et son procédé de fabrication Ceased WO2013161145A1 (fr)

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EP2804219A1 (fr) * 2013-05-16 2014-11-19 LG Electronics, Inc. Cellule solaire et son procédé de fabrication
JPWO2015115360A1 (ja) * 2014-01-29 2017-03-23 パナソニックＩｐマネジメント株式会社 太陽電池
EP4073849A4 (fr) * 2019-12-10 2023-12-13 Maxeon Solar Pte. Ltd. Métallisation alignée pour cellules solaires

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JP7449152B2 (ja) * 2020-04-23 2024-03-13 株式会社カネカ 太陽電池の製造方法および太陽電池

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JP2010080887A (ja) * 2008-09-29 2010-04-08 Sanyo Electric Co Ltd 太陽電池及びその製造方法
US20100108130A1 (en) * 2008-10-31 2010-05-06 Crystal Solar, Inc. Thin Interdigitated backside contact solar cell and manufacturing process thereof
JP2011155229A (ja) * 2010-01-28 2011-08-11 Sanyo Electric Co Ltd 太陽電池及び太陽電池の製造方法

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JP2010080887A (ja) * 2008-09-29 2010-04-08 Sanyo Electric Co Ltd 太陽電池及びその製造方法
US20100108130A1 (en) * 2008-10-31 2010-05-06 Crystal Solar, Inc. Thin Interdigitated backside contact solar cell and manufacturing process thereof
JP2011155229A (ja) * 2010-01-28 2011-08-11 Sanyo Electric Co Ltd 太陽電池及び太陽電池の製造方法

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EP2804219A1 (fr) * 2013-05-16 2014-11-19 LG Electronics, Inc. Cellule solaire et son procédé de fabrication
US10566484B2 (en) 2013-05-16 2020-02-18 Lg Electronics Inc. Solar cell and method for manufacturing the same
JPWO2015115360A1 (ja) * 2014-01-29 2017-03-23 パナソニックＩｐマネジメント株式会社 太陽電池
EP4073849A4 (fr) * 2019-12-10 2023-12-13 Maxeon Solar Pte. Ltd. Métallisation alignée pour cellules solaires
US12166137B2 (en) * 2019-12-10 2024-12-10 Maxeon Solar Pte. Ltd. Aligned metallization for solar cells
US12527114B2 (en) 2019-12-10 2026-01-13 Maxeon Solar Pte. Ltd. Aligned metallization for solar cells

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