WO2014014113A1 - Élément de cellule photovoltaïque, sa fabrication ainsi que module de cellule voltaïque - Google Patents

Élément de cellule photovoltaïque, sa fabrication ainsi que module de cellule voltaïque Download PDF

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WO2014014113A1
WO2014014113A1 PCT/JP2013/069703 JP2013069703W WO2014014113A1 WO 2014014113 A1 WO2014014113 A1 WO 2014014113A1 JP 2013069703 W JP2013069703 W JP 2013069703W WO 2014014113 A1 WO2014014113 A1 WO 2014014113A1
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passivation
solar cell
oxide
passivation layer
group
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Japanese (ja)
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WO2014014113A9 (fr
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明博 織田
吉田　誠人
野尻　剛
倉田　靖
田中　徹
修一郎 足立
剛 早坂
服部　孝司
三江子 松村
敬司 渡邉
真年 森下
浩孝 濱村
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日立化成株式会社
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Priority to JP2014525897A priority Critical patent/JP6295953B2/ja
Priority to CN201380038129.5A priority patent/CN104508831B/zh
Publication of WO2014014113A1 publication Critical patent/WO2014014113A1/fr
Publication of WO2014014113A9 publication Critical patent/WO2014014113A9/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0216—Coatings
    • H01L31/02161—Coatings for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/02167—Coatings for devices characterised by at least one potential jump barrier or surface barrier for solar cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0224—Electrodes
    • H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
    • H01L31/022433—Particular geometry of the grid contacts
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic Table
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/186—Particular post-treatment for the devices, e.g. annealing, impurity gettering, short-circuit elimination, recrystallisation
    • H01L31/1864—Annealing
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a solar cell element, a manufacturing method thereof, and a solar cell module.
  • n-type diffusion layer is uniformly formed by performing several tens of minutes at 800 ° C. to 900 ° C.
  • n-type diffusion layers are formed not only on the front surface, which is the light receiving surface, but also on the side surface and the back surface. Therefore, side etching is performed to remove the n-type diffusion layer formed on the side surface.
  • the n-type diffusion layer formed on the back surface needs to be converted into a p + -type diffusion layer. Therefore, aluminum powder on the entire back surface, glass frit, an aluminum paste applied containing a dispersion medium and organic binder and the like, by forming an aluminum electrode which heat treatment (firing) to the n-type diffusion layer p + In addition, an ohmic contact is obtained in the mold diffusion layer.
  • the aluminum electrode formed from the aluminum paste has low conductivity. Therefore, in order to reduce the sheet resistance, the aluminum electrode formed on the entire back surface usually has to have a thickness of about 10 ⁇ m to 20 ⁇ m after the heat treatment. Furthermore, since the thermal expansion coefficients of silicon and aluminum differ greatly, a large internal stress is generated in the silicon substrate during the heat treatment and cooling, which causes damage to crystal boundaries, increase of crystal defects, and warpage. .
  • a point contact method has been proposed in which an aluminum paste is applied to a part of the surface of a silicon substrate to partially form a p + -type diffusion layer and an aluminum electrode (for example, Japanese Patent No. 3107287). (See the publication).
  • an aluminum paste is applied to a part of the surface of a silicon substrate to partially form a p + -type diffusion layer and an aluminum electrode.
  • an aluminum electrode for example, Japanese Patent No. 3107287.
  • an SiO 2 layer or the like has been proposed as a backside semiconductor substrate passivation layer (hereinafter also simply referred to as “passivation layer”) (see, for example, Japanese Patent Application Laid-Open No.
  • Such a passivation effect is generally called a field effect, and aluminum oxide (Al 2 O 3 ) or the like has been proposed as a material having a negative fixed charge (see, for example, Japanese Patent No. 4767110).
  • Such a passivation layer is generally formed by a method such as an ALD (Atomic Layer Deposition) method or a CVD (Chemical Vapor Deposition) method (for example, Journal of Applied Physics, 104 (2008), 113703-1). 113703-7).
  • the method described in Journal of Applied Physics, 104 (2008), 113703-1 to 113703-7 includes a complicated manufacturing process such as vapor deposition, and thus it may be difficult to improve productivity.
  • the composition for forming a passivation layer used in the method described in Thin Solid Films, 517 (2009), 6327-6330 or Chinese Physics Letters, 26 (2009), 0881021-1-088102-4 is gelated over time. It is difficult to say that the storage stability is sufficient. Further, there has not been sufficiently studied to form a passivation layer having an excellent passivation effect using an oxide containing a metal element other than aluminum.
  • the present invention has been made in view of the above-described conventional problems, has a high conversion efficiency, a solar cell element in which deterioration of solar cell characteristics over time is suppressed, a simple manufacturing method thereof, and an excellent It is an object of the present invention to provide a solar cell module having high conversion efficiency and capable of suppressing deterioration of solar cell characteristics over time.
  • a semiconductor substrate having a light receiving surface and a back surface opposite to the light receiving surface; A first impurity diffusion region disposed in a part of the light receiving surface and in which impurities are diffused; A second impurity diffusion region disposed on the light receiving surface and having an impurity concentration lower than that of the first impurity diffusion region; A light-receiving surface electrode disposed in at least a part of the first impurity diffusion region; A back electrode disposed on the back surface; Passivation including at least one selected from the group consisting of Nb 2 O 5 , Ta 2 O 5 , V 2 O 5 , Y 2 O 3 and HfO 2 disposed on at least one of the light receiving surface and the back surface.
  • a solar cell element having a layer.
  • ⁇ 3> The solar cell element according to ⁇ 1> or ⁇ 2>, wherein the density of the passivation layer is 1.0 g / cm 3 to 10.0 g / cm 3 .
  • ⁇ 4> The solar cell element according to any one of ⁇ 1> to ⁇ 3>, wherein an average thickness of the passivation layer is 5 nm to 50 ⁇ m.
  • ⁇ 5> The solar cell element according to any one of ⁇ 1> to ⁇ 4>, wherein the passivation layer is a heat-treated product of the composition for a passivation film.
  • the composition for a passivation film is selected from the group consisting of Nb 2 O 5 , Ta 2 O 5 , V 2 O 5 , Y 2 O 3 , HfO 2 and a compound represented by the following general formula (I).
  • the solar cell element as described in ⁇ 5> containing 1 or more types by which it is carried out.
  • M (OR 1 ) m (I) [Wherein M includes at least one metal element selected from the group consisting of Nb, Ta, V, Y and Hf. R 1 independently represents an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 14 carbon atoms. m represents an integer of 1 to 5. ]
  • composition for forming a passivation layer further includes at least one aluminum compound selected from the group consisting of compounds represented by Al 2 O 3 and the following general formula (II). Solar cell element.
  • each R 2 independently represents an alkyl group having 1 to 8 carbon atoms.
  • n represents an integer of 0 to 3.
  • X 2 and X 3 each independently represent an oxygen atom or a methylene group.
  • R 3 , R 4 and R 5 each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.
  • each R 2 is independently an alkyl group having 1 to 4 carbon atoms.
  • composition for forming a passivation layer wherein the composition for forming a passivation layer contains one or more aluminum compounds selected from the group consisting of compounds represented by Al 2 O 3 and the general formula (II).
  • the solar cell element according to any one of ⁇ 7> to ⁇ 9>, wherein the total content of the aluminum compound in the product is 0.1% by mass to 80% by mass.
  • the passivation layer forming composition includes Nb 2 O 5 and one or more niobium compounds selected from the group consisting of compounds in which M is Nb in the general formula (I), and the passivation layer is formed.
  • the solar cell according to any one of ⁇ 6> to ⁇ 10>, wherein the total content of the niobium compound in the composition for use is 0.1% by mass to 99.9% by mass in terms of Nb 2 O 5 element.
  • ⁇ 12> The solar cell element according to any one of ⁇ 5> to ⁇ 11>, wherein the composition for forming a passivation layer includes a liquid medium.
  • the liquid medium includes at least one selected from the group consisting of a hydrophobic organic solvent, an aprotic organic solvent, a terpene solvent, an ester solvent, an ether solvent, and an alcohol solvent.
  • ⁇ 14> forming a first impurity diffusion region in a part of the light receiving surface of a semiconductor substrate having a light receiving surface and a back surface opposite to the light receiving surface; Forming a second impurity diffusion region having a lower impurity concentration than the first impurity diffusion region on the light receiving surface; Forming a light receiving surface electrode on at least a part of the first impurity diffusion region; forming a back electrode on the back surface; On at least one surface selected from the group consisting of the light receiving surface and the back surface, Nb 2 O 5 , Ta 2 O 5 , V 2 O 5 , Y 2 O 3 , HfO 2 and the following general formula (I) Providing a composition for forming a passivation layer containing at least one selected from the group consisting of the compounds represented to form a composition layer; Heat-treating the composition layer to form a passivation layer containing at least one selected from the group consisting of Nb 2 O 5 , Ta 2 O 5 , V 2 O 5 ,
  • M includes at least one metal element selected from the group consisting of Nb, Ta, V, Y, and Hf.
  • R 1 independently represents an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 14 carbon atoms.
  • m represents an integer of 1 to 5.
  • composition for forming a passivation layer further includes at least one selected from the group consisting of compounds represented by Al 2 O 3 and the following general formula (II). Device manufacturing method.
  • each R 2 independently represents an alkyl group having 1 to 8 carbon atoms.
  • n represents an integer of 0 to 3.
  • X 2 and X 3 each independently represent an oxygen atom or a methylene group.
  • R 3 , R 4 and R 5 each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.
  • ⁇ 16> The method for producing a solar cell element according to ⁇ 14> or ⁇ 15>, wherein the temperature of the heat treatment is 400 ° C. or higher.
  • the step of forming the composition layer includes applying the composition for forming a passivation layer by a screen printing method or an inkjet method, and the sun according to any one of ⁇ 14> to ⁇ 16> A battery element manufacturing method.
  • a solar cell module comprising the solar cell element according to any one of ⁇ 1> to ⁇ 13> and a wiring material disposed on an electrode of the solar cell element.
  • the solar cell element by which the fall of the solar cell characteristic with time is suppressed has the outstanding conversion efficiency, the solar cell element by which the fall of the solar cell characteristic with time is suppressed, its simple manufacturing method, and the solar cell which has the outstanding conversion efficiency, and with time It is possible to provide a solar cell module in which deterioration of characteristics is suppressed.
  • FIG. 1 It is sectional drawing which shows typically an example of the manufacturing method of the solar cell element concerning this embodiment. It is a top view which shows typically an example of back surface electrode arrangement
  • the term “process” is not limited to an independent process, and is included in the term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes.
  • a numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.
  • the content of each component in the composition means the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition.
  • the term “layer” includes a configuration of a shape formed in part in addition to a configuration of a shape formed on the entire surface when observed as a plan view.
  • the solar cell element of the present invention has a light receiving surface and a back surface opposite to the light receiving surface, The light receiving surface is disposed in at least a part of a first impurity diffusion region containing impurities, a second impurity diffusion region having an impurity concentration lower than that of the first impurity diffusion region, and the first impurity diffusion region.
  • the back surface has a back electrode; At least one selected from the group consisting of the light receiving surface and the back surface is one or more selected from the group consisting of Nb 2 O 5 , Ta 2 O 5 , V 2 O 5 , Y 2 O 3 and HfO 2 (
  • a passivation layer containing a metal element included in each metal oxide is also referred to as a “specific metal element”.
  • a solar cell element having a passivation layer containing an electrode and a specific metal oxide on the back surface of a semiconductor substrate has excellent conversion efficiency and suppresses deterioration of solar cell characteristics over time. This is considered to be because, for example, since the passivation layer contains a specific metal oxide, an excellent passivation effect is exhibited and the lifetime of carriers in the semiconductor substrate is extended, so that high efficiency can be achieved. Moreover, it is thought that the passivation effect of the passivation layer is maintained by containing the specific metal oxide, and the deterioration of the solar cell characteristics (for example, conversion efficiency) over time can be suppressed.
  • the deterioration of the solar cell characteristics over time can be evaluated by the solar cell characteristics after being left for a predetermined time in a constant temperature and humidity chamber.
  • a solar cell element having a passivation layer containing an electrode and a specific metal oxide on the back surface of a semiconductor substrate is excellent in conversion efficiency and suppresses deterioration of solar cell characteristics over time.
  • the specific metal oxide is a compound having a fixed charge. It can be considered that the presence of a compound having a fixed charge on the surface of the semiconductor substrate causes band bending and suppresses carrier recombination. Further, even if the compound has a small fixed charge or does not have a fixed charge, it may have a passivation effect such as having a function of repairing defects on the surface of the semiconductor substrate.
  • the fixed charge of the compound existing on the surface of the semiconductor substrate can be evaluated by a CV method (Capacitance Voltage Measurement).
  • a CV method Capacitance Voltage Measurement
  • the surface state density of a passivation layer formed by heat-treating a composition for forming a passivation layer, which will be described later, is evaluated by a CV method the value is larger than that of a passivation layer formed by an ALD method or a CVD method.
  • the passivation layer included in the solar cell element of the present invention has a large electric field effect, and the concentration of minority carriers is reduced, and the surface lifetime ⁇ s is increased. Therefore, the surface state density is not a relative problem.
  • the passivation effect of a semiconductor substrate refers to an effective lifetime of minority carriers in a semiconductor substrate on which a passivation layer is formed by using a device such as Nippon Semi-Lab Co., Ltd., WT-2000PVN, etc. It can be evaluated by measuring by the method.
  • the effective lifetime ⁇ is expressed by the following equation (A) by the bulk lifetime ⁇ b inside the semiconductor substrate and the surface lifetime ⁇ s of the semiconductor substrate surface.
  • ⁇ s becomes long, resulting in a long effective lifetime ⁇ .
  • the bulk lifetime ⁇ b is increased and the effective lifetime ⁇ is increased. That is, by measuring the effective lifetime ⁇ , the interface characteristics between the passivation layer and the semiconductor substrate and the internal characteristics of the semiconductor substrate such as dangling bonds can be evaluated.
  • the solar cell element includes a semiconductor substrate having a light receiving surface and a back surface opposite to the light receiving surface.
  • the semiconductor substrate include those obtained by doping (diffusing) p-type impurities or n-type impurities into silicon, germanium, or the like.
  • the semiconductor substrate may be a p-type semiconductor substrate or an n-type semiconductor substrate.
  • the surface on which the passivation layer is formed is a semiconductor substrate having a p-type layer.
  • the p-type layer on the semiconductor substrate is a p-type layer derived from the p-type semiconductor substrate
  • the p-type layer is formed on the n-type semiconductor substrate or the p-type semiconductor substrate as a p-type diffusion region or a p + -type diffusion region. It may be.
  • the p-type region and the n-type region are preferably pn-junction. That is, when the semiconductor substrate is a p-type semiconductor substrate, it is preferable that an n-type region is formed on the light receiving surface or the back surface of the semiconductor substrate. When the semiconductor substrate is an n-type semiconductor substrate, it is preferable that a p-type region is formed on the light receiving surface or the back surface of the semiconductor substrate.
  • the method for forming the p-type region or the n-type region in the semiconductor substrate is not particularly limited, and can be appropriately selected from commonly used methods.
  • the thickness of the semiconductor substrate is not particularly limited and can be appropriately selected according to the purpose. For example, it can be 50 ⁇ m to 1000 ⁇ m, and preferably 75 ⁇ m to 750 ⁇ m.
  • the shape and size of the semiconductor substrate are not particularly limited, and can be, for example, a square having a side of 125 mm to 156 mm.
  • the solar cell element of the present invention includes a semiconductor substrate having a light receiving surface electrode disposed on the light receiving surface and a back electrode disposed on the back surface opposite to the light receiving surface.
  • the light receiving surface electrode is disposed in at least a part of the first impurity diffusion region having a relatively high impurity concentration on the light receiving surface of the semiconductor substrate.
  • the light receiving surface electrode has a function of collecting current on the light receiving surface of the semiconductor substrate.
  • positioned at the back surface of a semiconductor substrate has a function which outputs an electric current outside, for example.
  • the material and thickness of the light receiving surface electrode There are no particular restrictions on the material and thickness of the light receiving surface electrode. Examples of the material of the light receiving surface electrode include silver, copper, and aluminum.
  • the thickness of the light-receiving surface electrode is preferably 0.1 ⁇ m to 50 ⁇ m from the viewpoint of conductivity and homogeneity.
  • the shape and size of the light receiving surface electrode are not particularly limited.
  • the size of the region where the light-receiving surface electrode is formed is preferably 50% or more, and more preferably 80% or more in the entire area of the first impurity diffusion region.
  • the material of the back electrode is not particularly limited, and examples thereof include silver, copper, and aluminum.
  • the material of the back electrode is preferably aluminum from the viewpoint of forming the back electrode and forming the p + -type diffusion region.
  • the thickness of the back electrode is not particularly limited, and is preferably 0.1 ⁇ m to 50 ⁇ m from the viewpoint of conductivity and substrate warpage.
  • the light-receiving surface electrode and the back surface electrode can be produced by a commonly used method.
  • it can be manufactured by applying an electrode forming paste such as a silver paste, an aluminum paste, or a copper paste to a desired region of a semiconductor substrate, and performing a heat treatment (firing) as necessary.
  • the first impurity diffusion region and the second impurity diffusion region are n-type diffusion regions or p-type diffusion regions.
  • the semiconductor substrate is a p-type semiconductor
  • the first n-type diffusion region as the first impurity diffusion region and the n-type diffusion region as the second impurity diffusion region are formed on the light-receiving surface of the semiconductor substrate more than the first n-type diffusion region.
  • a second n-type diffusion region having a low type impurity concentration is disposed. It is preferable that the first n-type diffusion region is disposed in a region where the light-receiving surface electrode is formed, and the second n-type diffusion region is disposed in a region other than the region where the light-receiving surface electrode is formed.
  • the contact resistance with the electrode can be lowered.
  • the series resistance can be lowered.
  • the second n-type diffusion region having a low impurity concentration in a region other than the region where the light receiving surface electrode is disposed, it is possible to effectively use short-wavelength sunlight. It is possible to reduce the recombination rate of electrons and holes generated by absorbing the. Such a structure is called a selective emitter structure.
  • the first p-type diffusion region as the first impurity diffusion region and the p-type diffusion region as the second impurity diffusion region are formed on the light receiving surface of the semiconductor substrate more than the first p-type diffusion region.
  • a second p-type diffusion region having a low type impurity concentration is disposed. It is preferable that the first p-type diffusion region is disposed in a region where the light-receiving surface electrode is formed, and the second p-type diffusion region is disposed in a region other than the region where the light-receiving surface electrode is formed.
  • the solar cell element having the selective emitter structure as described above can generate power with high conversion efficiency.
  • the sheet resistance in the first impurity diffusion region is preferably 20 ⁇ / ⁇ to 60 ⁇ / ⁇ , more preferably 30 ⁇ / ⁇ to 55 ⁇ / ⁇ , and 35 ⁇ / More preferably, ⁇ ⁇ 50 ⁇ / ⁇ .
  • the sheet resistance in the second impurity diffusion region is preferably 60 ⁇ / ⁇ to 150 ⁇ / ⁇ , more preferably 70 ⁇ / ⁇ to 130 ⁇ / ⁇ , and 80 ⁇ / ⁇ . More preferably, ⁇ to 120 ⁇ / ⁇ . Sheet resistance can be measured by a four-probe method.
  • the solar cell element of the present invention has a passivation layer containing a specific metal oxide on at least one of the light receiving surface and the back surface of the semiconductor substrate.
  • the passivation layer may be provided on a part or the whole of at least one of the light receiving surface and the back surface, and may be provided on a part or all of the region other than the region where the back electrode is disposed on the back surface.
  • the passivation layer may be provided in at least a part of the side surface and the light receiving surface of the semiconductor substrate in addition to the back surface.
  • the shape and size in the surface direction of the region where the passivation layer is formed on at least one of the light receiving surface and the back surface of the semiconductor substrate are not particularly limited and can be appropriately selected according to the purpose and the like.
  • the passivation layer is preferably formed on a part or all of the region other than the region where the back electrode is disposed, and the region where the back electrode is disposed More preferably, the passivation layer is formed in the entire region other than the above.
  • the content of the specific metal oxide contained in the passivation layer is preferably 0.1% by mass to 100% by mass from the viewpoint of obtaining a sufficient passivation effect, and 1% by mass to 100% by mass. Is more preferably 10% by mass to 100% by mass.
  • the content rate of the specific metal oxide contained in the passivation layer can be measured as follows. That is, the proportion of inorganic substances is calculated from thermogravimetric analysis using atomic absorption spectrometry, inductively coupled plasma emission spectroscopy, thermogravimetric analysis, X-ray photoelectric spectroscopy, or the like.
  • the proportion of the compound containing the specific metal element in the inorganic substance is calculated by atomic absorption spectrometry, inductively coupled plasma emission spectrometry, etc., and further the compound containing the specific metal element by X-ray photoelectric spectroscopy, X-ray absorption spectroscopy, etc. By calculating the ratio of the specific metal oxide, the content of the specific metal oxide can be obtained.
  • the passivation layer may further contain a metal oxide other than the specific metal oxide.
  • a metal oxide a compound having a fixed charge like the specific metal oxide is preferable.
  • the passivation layer is preferably aluminum oxide, silicon oxide, titanium oxide, zirconium oxide and neodymium oxide, and more preferably aluminum oxide from the viewpoint of obtaining a high passivation effect and a stable passivation effect.
  • the content is preferably 99.9% by mass or less, more preferably 80% by mass or less of the passivation layer.
  • the content rate of metal oxides other than the specific metal oxide contained in the passivation layer can be measured in the same manner as the measurement of the content rate of the specific metal oxide described above.
  • the passivation layer of the solar cell element of the present invention is a heat-treated product of the composition for forming a passivation layer.
  • the composition for forming a passivation layer is not particularly limited as long as it can form a passivation layer containing a specific metal oxide by heat treatment. Even if it contains the specific metal oxide itself, the metal containing the specific metal element A precursor of a specific metal oxide such as alkoxide may be included.
  • the specific metal oxide and its precursor are also referred to as a specific metal compound.
  • the specific metal compound is preferably at least one selected from the group consisting of the specific metal oxide itself and a compound represented by the following general formula (I) (hereinafter also referred to as a compound of formula (I)).
  • M includes at least one metal element selected from the group consisting of Nb, Ta, V, Y, and Hf.
  • R 1 independently represents an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 14 carbon atoms.
  • m represents an integer of 1 to 5.
  • M contains at least one metal element selected from the group consisting of Nb, Ta, V, Y, and Hf.
  • M is preferably Nb, Ta or Y.
  • M preferably contains at least one metal element selected from the group consisting of Nb, Ta, V, and Hf, and Nb, Ta, VO And at least one selected from the group consisting of Hf.
  • each R 1 independently represents an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 14 carbon atoms, and an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 8 carbon atoms. It is preferable that The alkyl group represented by R 1 may be linear or branched. Specific examples of the alkyl group represented by R 1 include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, 2-butyl, t-butyl, pentyl, hexyl, and heptyl groups. Octyl group, 2-ethylhexyl group, phenyl group and the like.
  • aryl group represented by R 1 examples include a phenyl group.
  • the alkyl group and aryl group represented by R 1 may have a substituent, and examples of the substituent of the alkyl group include a halogen atom, an amino group, a hydroxyl group, a carboxyl group, a sulfone group, and a nitro group.
  • substituent for the aryl group include a halogen atom, a methyl group, an ethyl group, an isopropyl group, an amino group, a hydroxyl group, a carboxyl group, a sulfone group, and a nitro group.
  • R 1 is preferably an unsubstituted alkyl group having 1 to 8 carbon atoms, and more preferably an unsubstituted alkyl group having 1 to 4 carbon atoms, from the viewpoint of storage stability and a passivation effect.
  • m represents an integer of 1 to 5.
  • M is preferably 5 when M is Nb, m is preferably 5 when M is Ta, and m is preferably 3 when M is VO.
  • M is preferably 3 when M is Y, and m is preferably 4 when M is Hf.
  • M is preferably Nb, Ta or Y from the viewpoint of the passivation effect, and R 1 has 1 to 4 carbon atoms from the viewpoint of storage stability and the passivation effect. It is more preferably an unsubstituted alkyl group, and m is preferably an integer of 1 to 5 from the viewpoint of storage stability.
  • the compound of formula (I) may be solid or liquid. From the viewpoint of the storage stability of the composition for forming a passivation layer and the compatibility with the organoaluminum compound represented by the general formula (II) described later, the compound of the formula (I) may be a liquid. preferable.
  • Compounds of formula (I) include niobium methoxide, niobium ethoxide, niobium isopropoxide, niobium n-propoxide, niobium n-butoxide, niobium t-butoxide, niobium isobutoxide, tantalum methoxide, tantalum ethoxide, tantalum Isopropoxide, tantalum n-propoxide, tantalum n-butoxide, tantalum t-butoxide, tantalum isobutoxide, yttrium methoxide, yttrium ethoxide, yttrium isopropoxide, yttrium n-propoxide, yttrium n-butoxide, yttrium t -Butoxide, yttrium isobutoxide, vanadium methoxide oxide, vanadium ethoxide oxide, van
  • niobium ethoxide, niobium n-propoxide, niobium n-butoxide, tantalum ethoxide, tantalum n-propoxide, tantalum n-butoxide, yttrium isopropoxide and yttrium n-butoxide are preferable.
  • niobium ethoxide, niobium n-propoxide, niobium n-butoxide, tantalum ethoxide, tantalum n-propoxide, tantalum n-butoxide, vanadium ethoxide oxide, vanadium n-propoxy Preference is given to oxides, vanadium n-butoxide oxide, hafnium ethoxide, hafnium n-propoxide and hafnium n-butoxide.
  • the compound of formula (I) may be a prepared product or a commercially available product.
  • Commercially available products include pentamethoxy niobium, pentaethoxy niobium, penta-i-propoxy niobium, penta-n-propoxy niobium, penta-i-butoxy niobium, penta-n-butoxy niobium, penta -2-butoxy niobium, pentamethoxy tantalum, pentaethoxy tantalum, penta-i-propoxy tantalum, penta-n-propoxy tantalum, penta-i-butoxy tantalum, penta-n-butoxy tantalum, penta-2-butoxy tantalum, penta -T-butoxy tantalum, vanadium (V) trimethoxide oxide, vanadium (V) triethoxy oxide, vanadium (V) tri-i-propoxide oxide,
  • the preparation method includes reacting a halide of the metal element (M) contained in the compound of formula (I) with an alcohol in the presence of an inert organic solvent, and further adding halogen.
  • Known methods such as a method of adding ammonia or an amine compound for extraction (see, for example, JP-A-63-227593 and JP-A-3-291247) can be used.
  • the content of the compound of formula (I) contained in the composition for forming a passivation layer can be appropriately selected as necessary.
  • the content of the compound of the formula (I) can be 0.1% by mass to 80% by mass in the composition for forming a passivation layer from the viewpoint of storage stability and a passivation effect, and 0.5% by mass to 70% by mass.
  • the content is preferably 1% by mass, more preferably 1% by mass to 60% by mass, and still more preferably 1% by mass to 50% by mass.
  • a chelating reagent (chelating agent) may be added.
  • dicarboxylic acid compounds such as EDTA (ethylenediaminetetraacetic acid), bipyridine, heme, naphthyridine, benzimidazolylmethylamine, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, tartaric acid, maleic acid, phthalic acid, etc.
  • ⁇ -diketone compounds, ⁇ -ketoester compounds, and malonic acid diester compounds from the viewpoint of chemical stability, ⁇ -diketone compounds and ⁇ -ketoester compounds are preferred.
  • ⁇ -diketone compounds include acetylacetone, 3-methyl-2,4-pentanedione, 2,3-pentanedione, 3-ethyl-2,4-pentanedione, and 3-butyl-2,4-pentane.
  • Examples include dione, 2,2,6,6-tetramethyl-3,5-heptanedione, 2,6-dimethyl-3,5-heptanedione, 6-methyl-2,4-heptanedione, and the like.
  • ⁇ -ketoester compounds include methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, isobutyl acetoacetate, butyl acetoacetate, t-butyl acetoacetate, pentyl acetoacetate, isopentyl acetoacetate, hexyl acetoacetate, acetoacetic acid n-octyl, heptyl acetoacetate, 3-pentyl acetoacetate, ethyl 2-acetylheptanoate, ethyl 2-butylacetoacetate, ethyl 4,4-dimethyl-3-oxovalerate, ethyl 4-methyl-3-oxovalerate Ethyl 2-ethylacetoacetate, ethyl hexylacetoacetate, methyl 4-methyl-3-oxovalerate, isopropyl acetoacetate, e
  • malonic acid diester compound examples include dimethyl malonate, diethyl malonate, dipropyl malonate, diisopropyl malonate, dibutyl malonate, di-t-butyl malonate, dihexyl malonate, t-butylethyl malonate, and methylmalon.
  • examples include diethyl acid, diethyl ethylmalonate, diethyl isopropylmalonate, diethyl butylmalonate, diethyl 2-butylmalonate, diethyl isobutylmalonate, diethyl 1-methylbutylmalonate, and the like.
  • the presence of the chelate structure can be confirmed by a commonly used analytical method. For example, it can be confirmed using an infrared spectrum, a nuclear magnetic resonance spectrum, a melting point, or the like.
  • the compound of formula (I) may be used in a state of hydrolysis and dehydration condensation polymerization.
  • the reaction can proceed in the presence of water and a catalyst.
  • water and catalyst may be distilled off.
  • Catalysts include inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, boric acid, phosphoric acid, hydrofluoric acid; and formic acid, acetic acid, propionic acid, butyric acid, oleic acid, linoleic acid, salicylic acid, benzoic acid, phthalic acid, oxalic acid And organic acids such as lactic acid and succinic acid.
  • bases such as ammonia and an amine, as a catalyst.
  • the passivation layer forming composition may contain a precursor of a specific metal oxide other than the compound of formula (I).
  • the precursor of a specific metal oxide will not be restrict
  • the passivation layer forming composition may further include a metal oxide other than the specific metal compound or a precursor thereof.
  • metal oxides or precursors thereof include aluminum oxide, silicon oxide, titanium oxide, gallium oxide, zirconium oxide, boron oxide, indium oxide, phosphorus oxide, zinc oxide, lanthanum oxide, praseodymium oxide, neodymium oxide, and oxidation. Mention may be made of promethium, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide, and precursors thereof.
  • aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, neodymium oxide or a precursor thereof is preferable, and from the viewpoint of a high passivation effect, aluminum oxide or a precursor thereof is more preferable.
  • the composition for forming a passivation layer preferably contains one or more selected from the group consisting of aluminum oxide and a precursor thereof in addition to the specific metal compound.
  • a precursor of aluminum oxide a compound represented by the following general formula (II) (hereinafter also referred to as an organoaluminum compound) is preferable.
  • the organoaluminum compound is a compound called aluminum alkoxide, aluminum chelate or the like. As described in Nippon Seramikkusu Kyokai Gakujitsu Ronbunshi, 97 (1989) 369-399, the organoaluminum compound becomes aluminum oxide (Al 2 O 3 ) by heat treatment.
  • each R 2 independently represents an alkyl group having 1 to 8 carbon atoms.
  • n represents an integer of 0 to 3.
  • X 2 and X 3 each independently represent an oxygen atom or a methylene group.
  • R 3 , R 4 and R 5 each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.
  • each R 2 independently represents an alkyl group having 1 to 8 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms.
  • the alkyl group represented by R 2 may be linear or branched. Specific examples of the alkyl group represented by R 2 include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, 2-butyl group, t-butyl group, hexyl group, octyl group, and ethylhexyl group. Etc.
  • the alkyl group represented by R 2 is preferably an unsubstituted alkyl group having 1 to 8 carbon atoms from the viewpoint of storage stability and a passivation effect, and is an unsubstituted alkyl group having 1 to 4 carbon atoms. More preferably.
  • n represents an integer of 0 to 3. n is preferably an integer of 1 to 3 and more preferably 1 or 3 from the viewpoint of storage stability.
  • X 2 and X 3 each independently represent an oxygen atom or a methylene group. From the viewpoint of storage stability, at least one of X 2 and X 3 is preferably an oxygen atom.
  • R 3 , R 4 and R 5 each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.
  • the alkyl group represented by R 3 , R 4 and R 5 may be linear or branched.
  • the alkyl group represented by R 3 , R 4 and R 5 may have a substituent or may be unsubstituted, and is preferably unsubstituted.
  • the alkyl groups represented by R 3 , R 4 and R 5 are each independently an alkyl group having 1 to 8 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms.
  • alkyl group represented by R 3 , R 4 and R 5 include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a 2-butyl group, a t-butyl group, and a hexyl group.
  • Octyl group, 2-ethylhexyl group, 3-ethylhexyl group and the like are preferably each independently a hydrogen atom or an unsubstituted alkyl group having 1 to 8 carbon atoms.
  • R 5 in the general formula (II) is preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 8 carbon atoms from the viewpoint of storage stability and a passivation effect, and is preferably a hydrogen atom or a carbon atom having 1 to 4 carbon atoms. It is more preferably an unsubstituted alkyl group.
  • n is an integer of 1 to 3
  • R 5 is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. A certain compound is preferable.
  • the organoaluminum compound represented by the general formula (II) is a compound in which n is 0 and R 2 is each independently an alkyl group having 1 to 4 carbon atoms from the viewpoint of storage stability and a passivation effect, n is 1 to 3, R 2 is each independently an alkyl group having 1 to 4 carbon atoms, at least one of X 2 and X 3 is an oxygen atom, and R 3 and R 4 are each independently It is preferably at least one selected from the group consisting of a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R 5 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
  • n is 0, R 2 is each independently an unsubstituted alkyl group having 1 to 4 carbon atoms, and n is 1 to 3 R 2 is each independently an unsubstituted alkyl group having 1 to 4 carbon atoms, at least one of X 2 and X 3 is an oxygen atom, and R 3 or R 4 bonded to the oxygen atom is A group consisting of a compound having a C 1-4 alkyl group, and when X 2 or X 3 is a methylene group, R 3 or R 4 bonded to the methylene group is a hydrogen atom, and R 5 is a hydrogen atom More preferably, it is at least one selected from more.
  • aluminum trialkoxide which is an organoaluminum compound represented by the general formula (II) and n is 0, include trimethoxyaluminum, triethoxyaluminum, triisopropoxyaluminum, tri-2-butoxyaluminum, mono-2-butoxy -Diisopropoxyaluminum, tri-t-butoxyaluminum, tri-n-butoxyaluminum and the like.
  • organoaluminum compound represented by the general formula (II) where n is 1 to 3 include aluminum ethyl acetoacetate diisopropylate, tris (ethyl acetoacetate) aluminum and the like.
  • organoaluminum compound represented by the general formula (II) and n being 1 to 3 a prepared product or a commercially available product may be used.
  • commercially available products include Kawaken Fine Chemical Co., Ltd. trade names, ALCH, ALCH-50F, ALCH-75, ALCH-TR, ALCH-TR-20, and the like.
  • the organoaluminum compound preferably has n of 1 to 3, that is, has an aluminum chelate structure in addition to the aluminum alkoxide structure.
  • n is 0, that is, when it exists in the composition for forming a passivation layer in the state of an aluminum alkoxide structure, it is preferable to add a chelating reagent (chelating agent) to the composition for forming a passivation layer.
  • chelating reagents include those described above.
  • the presence of the chelate structure can be confirmed by a commonly used analysis method. For example, it can be confirmed using an infrared spectrum, a nuclear magnetic resonance spectrum, a melting point, or the like.
  • the thermal and chemical stability of the organoaluminum compound is improved, and the transition to aluminum oxide during heat treatment is suppressed. it is conceivable that. As a result, it is considered that the transition to thermodynamically stable crystalline aluminum oxide is suppressed, and amorphous aluminum oxide is easily formed.
  • the state of the metal oxide in the formed passivation layer can be confirmed by measuring an X-ray diffraction spectrum (XRD, X-ray diffraction). For example, it can be confirmed that the XRD has an amorphous structure by not showing a specific reflection pattern.
  • XRD X-ray diffraction spectrum
  • the composition for forming a passivation layer contains an organoaluminum compound
  • the aluminum oxide is in an amorphous state, aluminum deficiency or oxygen deficiency is likely to occur, fixed charges are likely to be generated in the passivation layer, and a large passivation effect is likely to be obtained.
  • the organoaluminum compound represented by the general formula (II) and n is 1 to 3 can be prepared by mixing the aluminum trialkoxide and a chelating reagent.
  • the chelating reagent include compounds having a specific structure having two carbonyl groups. Specifically, when the aluminum trialkoxide is mixed with a compound having a specific structure having two carbonyl groups, at least a part of the alkoxide group of the aluminum trialkoxide is substituted with a compound having a specific structure, thereby forming an aluminum chelate structure. Form. At this time, if necessary, a solvent may be present, or heat treatment or addition of a catalyst may be performed.
  • the stability of the organoaluminum compound to hydrolysis and polymerization reaction is improved, and the storage stability of the composition for forming a passivation layer containing this is further improved. To do.
  • the compound having a specific structure having two carbonyl groups is at least one selected from the group consisting of ⁇ -diketone compounds, ⁇ -ketoester compounds, and malonic acid diesters from the viewpoint of reactivity and storage stability. preferable.
  • Specific examples of the ⁇ -diketone compound, ⁇ -ketoester compound and malonic acid diester include the compounds described above as chelating reagents.
  • the number of aluminum chelate structures is not particularly limited as long as it is 1 to 3. Among these, 1 or 3 is preferable from the viewpoint of storage stability, and 1 is more preferable from the viewpoint of solubility.
  • the number of aluminum chelate structures can be controlled, for example, by appropriately adjusting the ratio of mixing the aluminum trialkoxide and a compound capable of forming a chelate with aluminum. Moreover, you may select suitably the compound which has a desired structure from a commercially available aluminum chelate compound.
  • organoaluminum compounds represented by the general formula (II) from the viewpoint of the passivation effect and the compatibility with the solvent added as necessary, specifically, aluminum ethylacetoacetate diisopropylate and triisopropoxyaluminum It is preferable to use at least one selected from the group consisting of, and more preferable to use aluminum ethyl acetoacetate diisopropylate.
  • the organoaluminum compound may be liquid or solid and is not particularly limited. From the viewpoint of the passivation effect and storage stability, the uniformity of the passivation layer formed can be achieved by using an organoaluminum compound that is stable at room temperature (about 10 ° C to 40 ° C) and has good solubility or dispersibility. It can improve further and can acquire the desired passivation effect stably.
  • the composition for forming a passivation layer contains one or more aluminum compounds selected from the group consisting of Al 2 O 3 and the organoaluminum compound
  • the total content of the aluminum compounds in the composition for forming a passivation layer The rate is preferably 0.1% by mass to 80% by mass, and more preferably 10% by mass to 70% by mass.
  • the total ratio of the aluminum compound in the total amount of the specific metal compound and the aluminum compound is preferably 0.1% by mass or more and 99.9% by mass or less, The content is more preferably no less than 99% and no more than 99% by mass, and still more preferably no less than 1% and no more than 95% by mass.
  • the composition of the specific metal oxide in the passivation layer obtained by heat-treating the composition for forming a passivation layer is Nb 2 O 5 —Al 2 O 3 , Binary complex oxides such as Al 2 O 3 —Ta 2 O 5 , Al 2 O 3 —Y 2 O 3 , Al 2 O 3 —V 2 O 5 , Al 2 O 3 —HfO 2 ; Nb 2 O 5 —Al 2 O 3 —Ta 2 O 5 , Al 2 O 3 —Y 2 O 3 —Ta 2 O 5 , Nb 2 O 5 —Al 2 O 3 —V 2 O 5 , Al 2 O 3 —HfO 2 —Ta Examples thereof include ternary complex oxides such as 2 O 5 .
  • the composition for forming a passivation layer is selected from the group consisting of Nb 2 O 5 and a compound in which M is Nb in the general formula (I). It is preferable to contain at least one niobium compound.
  • the total content of the niobium compound in the composition for forming a passivation layer is preferably 0.1% by mass to 99.9% by mass in terms of Nb 2 O 5 , and preferably 1% by mass to 99% by mass. More preferably, it is more preferably 5% by mass to 90% by mass.
  • the composition of the metal oxide include Nb 2 O 5 —Al 2 O 3 , Nb 2 O 5 —Ta 2 O 5 , Nb 2 O 5 —Y 2 O 3 , Nb 2 O 5 —V 2 O 5 , Binary complex oxides such as Nb 2 O 5 —HfO 2 ; Nb 2 O 5 —Al 2 O 3 —Ta 2 O 5 , Nb 2 O 5 —Y 2 O 3 —Ta 2 O 5 , Nb 2 O 5 Examples thereof include ternary complex oxides such as —Al 2 O 3 —V 2 O 5 and Nb 2 O 5 —HfO 2 —Ta 2 O 5 .
  • a composition for forming a passivation layer containing a specific metal compound is applied to a semiconductor substrate to form a composition layer having a desired shape, and the composition layer is heat-treated to obtain a desired passivation layer having an excellent passivation effect. It can be formed into a shape.
  • a passivation layer having an excellent passivation effect can be formed by heat-treating the composition for forming a passivation layer as follows. It is considered that when the composition for forming a passivation layer containing a specific metal compound is heat-treated, defects such as metal atoms and oxygen atoms are generated and a large fixed charge is generated in the vicinity of the interface with the semiconductor substrate. This large fixed charge generates an electric field in the vicinity of the interface of the semiconductor substrate, so that the concentration of minority carriers can be reduced. As a result, the carrier recombination rate at the interface is suppressed, so that it has an excellent passivation effect. It is believed that a passivation layer can be formed. Furthermore, it is thought that the composition for forming a passivation layer is excellent in storage stability over time because the occurrence of problems such as gelation is suppressed.
  • the composition for forming a passivation layer preferably contains a liquid medium.
  • the viscosity can be adjusted more easily, the applicability can be further improved, and a more uniform passivation layer can be formed.
  • the liquid medium is not particularly limited as long as it can dissolve or disperse the specific metal compound, and can be appropriately selected as necessary.
  • liquid medium examples include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl isopropyl ketone, methyl-n-butyl ketone, methyl isobutyl ketone, methyl-n-pentyl ketone, methyl-n-hexyl ketone, diethyl ketone, Ketone solvents such as dipropyl ketone, diisobutyl ketone, trimethylnonanone, cyclohexanone, cyclopentanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone; diethyl ether, methyl ethyl ether, methyl-n-propyl ether, diisopropyl Ether, tetrahydrofuran, methyltetrahydrofuran, dioxane, dimethyldioxane, ethylene glycol dimethyl ether
  • the liquid medium is a group consisting of a terpene solvent, an ester solvent, and an alcohol solvent from the viewpoint of impartability to a semiconductor substrate and pattern formability (inhibition of pattern enlargement during application of a passivation layer forming composition and drying). It is preferable to include at least one selected from the above, and it is more preferable to include at least one terpene solvent.
  • the content is determined in consideration of the imparting property, pattern forming property, and storage stability.
  • the content of the liquid medium is preferably 5% by mass to 98% by mass with respect to the total mass of the passivation layer forming composition from the viewpoint of the impartability of the composition and the pattern forming property, and 10% by mass to 95% by mass. % Is more preferable.
  • the composition for forming a passivation layer further contains at least one resin.
  • the shape stability of the composition layer formed by applying the passivation layer-forming composition on the semiconductor substrate is further improved, and the passivation layer is desired in the region where the composition layer is formed. It becomes easier to selectively form with this shape.
  • the type of the resin is not particularly limited, and is preferably a resin whose viscosity can be adjusted within a range where a good pattern can be formed when the composition for forming a passivation layer is applied on a semiconductor substrate.
  • the resin include cellulose derivatives such as polyvinyl alcohol, polyacrylamide, polyvinylamide, polyvinylpyrrolidone, polyethylene oxide, polysulfone, polyacrylamide alkylsulfone, cellulose ether such as cellulose, carboxymethylcellulose, hydroxyethylcellulose, ethylcellulose, gelatin, and gelatin.
  • the molecular weight of the resin is not particularly limited, and is preferably adjusted appropriately in view of the desired viscosity as the composition for forming a passivation layer.
  • the weight average molecular weight of the resin is preferably 1,000 to 10,000,000, more preferably 3,000 to 5,000,000, from the viewpoints of storage stability and pattern formation.
  • the weight average molecular weight of resin is calculated
  • the calibration curve is approximated by a cubic equation using 5 standard polystyrene sample sets (PStQuick MP-H, PStQuick B [trade name, manufactured by Tosoh Corporation]).
  • PStQuick MP-H, PStQuick B trade name, manufactured by Tosoh Corporation
  • the content of the resin in the composition for forming a passivation layer can be appropriately selected as necessary.
  • the content is preferably 0.1% by mass to 30% by mass in the total mass of the composition for forming a passivation layer.
  • the content is more preferably 1% by mass to 25% by mass, and further preferably 1.5% by mass to 20% by mass. More preferably, the content is 1.5 to 10% by mass.
  • the content ratio of the organoaluminum compound and the resin in the composition for forming a passivation layer can be appropriately selected as necessary.
  • the ratio of the resin when the total amount of one or more selected from the group consisting of the specific metal compound and the aluminum oxide and precursor thereof contained as necessary is 1. Is preferably 0.001 to 1000, more preferably 0.01 to 100, and still more preferably 0.1 to 1.
  • the composition for forming a passivation layer may contain an acidic compound or a basic compound.
  • the content of the acidic compound or the basic compound in the composition for forming a passivation layer is 1% by mass or less, respectively. It is preferable that the content is 0.1% by mass or less.
  • Examples of acidic compounds include Bronsted acid and Lewis acid. Specific examples include inorganic acids such as hydrochloric acid and nitric acid, and organic acids such as acetic acid. Examples of basic compounds include Bronsted bases and Lewis bases. Specific examples include inorganic bases such as alkali metal hydroxides and alkaline earth metal hydroxides; organic bases such as trialkylamines and pyridines.
  • the composition for forming a passivation layer contains various additives such as a thickener, a wetting agent, a surfactant, an inorganic powder, a resin containing a silicon atom, a thixotropic agent, as other components, as necessary. Also good.
  • the inorganic powder examples include silica (silicon oxide), clay, silicon carbide, silicon nitride, montmorillonite, bentonite, and carbon black. Among these, it is preferable to use a filler containing silica as a component.
  • clay refers to a layered clay mineral, and specific examples include kaolinite, imogolite, montmorillonite, smectite, sericite, illite, talc, stevensite, and zeolite.
  • the composition for forming a passivation layer contains an inorganic powder, the impartability of the composition for forming a passivation layer tends to be improved.
  • the surfactant examples include nonionic surfactants, cationic surfactants, anionic surfactants and the like. Among these, nonionic surfactants or cationic surfactants are preferred because impurities such as heavy metals are not brought into the semiconductor device. Examples of nonionic surfactants include silicon surfactants, fluorine surfactants, and hydrocarbon surfactants. When the composition for forming a passivation layer contains a surfactant, the thickness and composition uniformity of the composition layer formed from the composition for forming a passivation layer tend to be improved.
  • the resin containing silicon atoms include lysine-modified silicones at both ends, polyamide-silicone alternating copolymers, side-chain alkyl-modified silicones, side-chain polyether-modified silicones, terminal alkyl-modified silicones, silicone-modified pullulans, and silicone-modified acrylic resins. It can be illustrated.
  • the composition for forming a passivation layer contains a resin containing silicon, the thickness and composition uniformity of the composition layer formed from the composition for forming a passivation layer tend to be improved.
  • thixotropic agents include polyether compounds, fatty acid amides, fumed silica, hydrogenated castor oil, urea urethane amide, polyvinyl pyrrolidone, and oil-based gelling agents.
  • the composition for forming a passivation layer contains a thixotropic agent, the pattern formability when applying the composition for forming a passivation layer tends to be improved.
  • the polyether compound include polyethylene glycol, polypropylene glycol, poly (ethylene-propylene) glycol copolymer and the like.
  • the viscosity of the composition for forming a passivation layer is not particularly limited, and can be appropriately selected depending on a method for applying the composition to a semiconductor substrate.
  • the viscosity of the composition for forming a passivation layer can be 0.01 Pa ⁇ s to 10,000 Pa ⁇ s.
  • the viscosity of the composition for forming a passivation layer is preferably 0.1 Pa ⁇ s to 1000 Pa ⁇ s.
  • the viscosity is a value measured at 25 ° C. and a shear rate of 1.0 s ⁇ 1 using a rotary shear viscometer.
  • the composition for forming a passivation layer has thixotropy.
  • the passivation layer forming composition comprising a resin from the viewpoint of pattern formability is calculated by dividing the shear viscosity eta 1 at a shear rate of 1.0 s -1 at shear viscosity eta 2 at a shear rate of 10s -1
  • the thixo ratio ( ⁇ 1 / ⁇ 2 ) is preferably 1.05 to 100, more preferably 1.1 to 50.
  • the shear viscosity is measured at a temperature of 25 ° C. using a rotary shear viscometer equipped with a cone plate (diameter 50 mm, cone angle 1 °).
  • a specific metal compound and a liquid medium or the like contained as necessary can be mixed and produced by a commonly used method.
  • the specific metal compound may be prepared by mixing the compound of formula (I) and a compound capable of forming a chelate with the metal element contained in the compound of formula (I). At that time, a solvent may be appropriately used or heat treatment may be performed.
  • a composition for forming a passivation layer may be produced using the specific metal compound thus prepared.
  • the components contained in the composition for forming a passivation layer and the content of each component are determined by thermal analysis such as thermal-thermogravimetric simultaneous measurement (TG / DTA), nuclear magnetic resonance (NMR), infrared spectroscopy. It can be confirmed by spectral analysis such as (IR), chromatographic analysis such as high performance liquid chromatography (HPLC), gel permeation chromatography (GPC) and the like.
  • thermal analysis such as thermal-thermogravimetric simultaneous measurement (TG / DTA), nuclear magnetic resonance (NMR), infrared spectroscopy. It can be confirmed by spectral analysis such as (IR), chromatographic analysis such as high performance liquid chromatography (HPLC), gel permeation chromatography (GPC) and the like.
  • the manufacturing method of the solar cell element of the present invention is as follows: Forming a first impurity diffusion region in a part of the light receiving surface of a semiconductor substrate having a light receiving surface and a back surface opposite to the light receiving surface; Forming a second impurity diffusion region having a lower impurity concentration than the first impurity diffusion region on the light receiving surface; Forming a light receiving surface electrode in at least a part of the first impurity diffusion region; forming a back electrode on the back surface; For forming a passivation layer containing at least one selected from the group consisting of a specific metal oxide and a compound represented by formula (I) on at least one surface selected from the group consisting of the light receiving surface and the back surface Applying the composition to form a composition layer; And heat-treating the composition layer to form a passivation layer containing at least one specific metal oxide.
  • the method for manufacturing a solar cell element of the present invention may further include other steps as necessary.
  • a passivation layer having an excellent passivation effect can be formed on the semiconductor substrate. Furthermore, the passivation layer can be formed by a simple and highly productive method that does not require a vapor deposition apparatus or the like.
  • a semiconductor substrate having an impurity diffusion region can be manufactured by a commonly used method. For example, it can be produced according to the method described in Japanese Patent No. 3522940.
  • a method for forming the light receiving surface electrode in at least a part of the first impurity diffusion region for example, a paste for forming an electrode such as a silver paste or an aluminum paste is applied to a desired region of the light receiving surface of the semiconductor substrate. It can be formed by heat treatment according to the above.
  • the step of forming the electrode may be performed before the step of forming the passivation layer, or may be performed after the step of forming the passivation layer.
  • the method for forming a composition layer by applying a composition for forming a passivation layer containing a specific metal compound on at least one surface selected from the group consisting of a light receiving surface and a back surface of a semiconductor substrate is not particularly limited.
  • Specific examples include a printing method such as an immersion method and a screen printing method, a spin coating method, a brush coating method, a spray method, a doctor blade method, a roll coater method, and an ink jet method.
  • a printing method and an inkjet method are preferable, and a screen printing method is more preferable.
  • the amount of the passivation layer forming composition applied to the semiconductor substrate can be appropriately selected depending on the purpose.
  • the thickness of the passivation layer to be formed can be appropriately adjusted so as to have a desired thickness.
  • the passivation layer is formed on the semiconductor substrate by heat-treating the composition layer formed by applying the passivation layer-forming composition on the semiconductor substrate to form a heat-treated material layer derived from the composition layer.
  • the heat treatment conditions for the composition layer are not particularly limited as long as a passivation layer containing a specific metal oxide is formed.
  • the composition for forming a passivation layer contains a precursor of a specific oxide, there is no particular limitation as long as the precursor of the specific oxide is converted into a specific metal oxide that is a heat-treated product.
  • the firing conditions are such that an amorphous specific metal oxide layer having no crystal structure can be formed.
  • the semiconductor substrate passivation layer can effectively have a negative charge, and a more excellent passivation effect can be obtained.
  • the heat treatment temperature is preferably 400 ° C. or higher, more preferably 400 ° C. to 900 ° C., and still more preferably 600 ° C. to 800 ° C.
  • the heat treatment time can be appropriately selected according to the heat treatment temperature and the like. For example, it can be 5 seconds to 10 hours, and is preferably 10 seconds to 5 hours.
  • the density of the passivation layer is preferably 1.0 g / cm 3 to 10.0 g / cm 3 , more preferably 2.0 g / cm 3 to 8.0 g / cm 3 , and 3.0 g / cm 3 More preferably, it is ⁇ 7.0 g / cm 3 .
  • the density of the passivation layer is 1.0 g / cm 3 to 10.0 g / cm 3 , a sufficient passivation effect is obtained, and the high passivation effect tends to hardly change over time.
  • the density of the passivation layer is 1.0 g / cm 3 or more, the moisture and impurity gas in the outside world do not easily reach the interface between the semiconductor substrate and the passivation layer, and the passivation effect is easily sustained. It is presumed that the interaction with the semiconductor substrate tends to increase when the concentration is 0.0 g / cm 3 or less.
  • a method for measuring the density of the passivation layer a method for measuring and calculating the mass and volume of the passivation layer, and an X-ray reflectivity method to make X-rays incident on the sample surface at a very shallow angle, the incident angle in the mirror surface direction. Examples include a method of determining the film thickness and density of a sample by measuring a reflected X-ray intensity profile, comparing the profile obtained by the measurement with simulation results, and optimizing simulation parameters.
  • the average thickness of the passivation layer is preferably 5 nm to 50 ⁇ m, more preferably 20 nm to 20 ⁇ m, and still more preferably 30 nm to 5 ⁇ m. If the average thickness of the passivation layer is 5 nm or more, a sufficient passivation effect can be easily obtained, and if it is 50 ⁇ m or less, the element structure can be designed in consideration of other members constituting the solar cell element. is there.
  • the average thickness of the passivation layer is an arithmetic average value of five thicknesses measured using an interference film thickness meter.
  • FIG. 1 is a sectional view schematically showing an example of a method for manufacturing a solar cell element according to this embodiment.
  • this process diagram does not limit the present invention.
  • the p-type semiconductor substrate 10 it is preferable to clean the p-type semiconductor substrate 10 with an alkaline aqueous solution.
  • an alkaline aqueous solution By washing with an alkaline aqueous solution, organic substances, particles and the like present on the surface of the semiconductor substrate can be removed, and the passivation effect is further improved.
  • a method for cleaning with an alkaline aqueous solution generally known RCA cleaning and the like can be exemplified.
  • the organic substance and particles can be removed by immersing the semiconductor substrate in a mixed solution of ammonia water and hydrogen peroxide solution and treating the substrate at 60 ° C. to 80 ° C.
  • the treatment time is preferably 10 seconds to 10 minutes, more preferably 30 seconds to 5 minutes.
  • a texture structure for suppressing reflection of sunlight is formed on the light receiving surface of the p-type semiconductor substrate 10 by alkali etching or the like.
  • the n-type diffusion region forming composition 11 is applied to a part of the light receiving surface, and the impurities are diffused into the semiconductor substrate by heat treatment as shown in FIG. A first impurity diffusion region (first n-type diffusion region 13) is formed.
  • a composition containing phosphorus or antimony can be used as the n-type diffusion region forming composition.
  • the temperature of the heat treatment is preferably 800 ° C. to 1000 ° C.
  • the n-type diffusion region forming composition for example, those described in JP 2012-084830 A may be used.
  • a PSG (phosphosilicate glass) layer 14 is formed using phosphorus oxychloride or the like, heat treatment is performed, and second impurity diffusion is performed as shown in FIG. 1 (e). A region (second n-type diffusion region 15) is formed. Thereafter, as shown in FIG. 1F, the PSG layer 14 and the fired product 12 of the n-type diffusion region forming composition are removed by immersing the semiconductor substrate in an etchant such as hydrofluoric acid.
  • an etchant such as hydrofluoric acid.
  • a p-type diffusion region forming composition 16 is applied to the back surface of the p-type semiconductor substrate 10.
  • the p-type diffusion region forming composition may be applied to a part of the back surface of the p-type semiconductor substrate 10 or to the entire surface.
  • a composition containing boron or the like can be used as the p-type diffusion region forming composition.
  • impurities are diffused by heat treatment to form a p + -type diffusion region 17.
  • the heat treatment temperature is preferably 800 ° C. to 1050 ° C.
  • the p-type diffusion region forming composition for example, the one described in JP2011-005312A can be used.
  • the fired product 16 'of the p-type diffusion region forming composition is removed by immersing the semiconductor substrate in an etching solution such as hydrofluoric acid.
  • an antireflection film 18 is formed on the light receiving surface of the p-type semiconductor substrate 10.
  • the antireflection film 18 include a silicon nitride film and a titanium oxide film.
  • a surface protective film such as silicon oxide may further exist between the antireflection film 18 and the p-type semiconductor substrate 10.
  • a passivation layer forming composition containing a specific metal compound is applied to a partial region of the back surface of the p-type semiconductor substrate 10 to form a composition layer.
  • the physical layer is heat-treated to form a passivation layer 19.
  • the method for applying the composition for forming a passivation layer is not particularly limited.
  • a dipping method, a printing method such as screen printing, a spin coating method, a brush coating, a spray method, a doctor blade method, a roll coater method, an ink jet method, and the like can be given.
  • the printing method and the inkjet method are preferable from the viewpoint of pattern formation, and the screen printing method is more preferable.
  • the application amount of the composition for forming a passivation layer can be appropriately selected according to the purpose.
  • the application amount of the composition for forming a passivation layer can be appropriately adjusted so that the thickness of the passivation layer 19 to be formed is the above-described preferable thickness.
  • the conditions for the heat treatment of the composition layer can be appropriately selected from the conditions described above.
  • an electrode-forming paste is applied to the light-receiving surface and the back surface side of the p-type semiconductor substrate 10, and heat treatment is performed.
  • a back electrode 21 is formed.
  • the electrode 20 can be formed to obtain an ohmic contact.
  • a solar cell element can be obtained.
  • FIG. 1M there may be a region where the passivation layer 19 and the back electrode 21 overlap.
  • the back electrode formed from aluminum or the like can have a point contact structure (for example, the electrode arrangement shown in FIG. 2), and the warpage of the substrate can be reduced. Can be reduced. Furthermore, a passivation layer can be formed with excellent productivity by applying the composition for forming a passivation layer to a desired region on the surface of the semiconductor substrate and performing a heat treatment.
  • the solar cell element of the present invention can also be manufactured using an n-type semiconductor substrate.
  • the p-type semiconductor substrate 10 is an n-type semiconductor substrate
  • the n-type diffusion region forming composition 11 is a p-type diffusion region forming composition
  • the n-type diffusion region forming composition is formed.
  • the fired product 12 is a fired product of the p-type diffusion region forming composition
  • the first n-type diffusion region 13 is the first p-type diffusion region
  • the second n-type diffusion region 15 is the second p-type diffusion region.
  • the p-type diffusion region forming composition 16 is used as an n-type diffusion region forming composition
  • the p-type diffusion region forming composition fired product 16 ′ is used as a n-type diffusion region forming composition fired product
  • a p + -type diffusion region It can be manufactured by replacing 17 with an n + -type diffusion region and PSG (phosphor silicate glass) layer 14 with a BSG (boron silicate glass) layer.
  • FIG. 2 is a plan view schematically showing an example of the arrangement of the back electrode 21 in the semiconductor substrate on which the back electrode 21 is formed.
  • a plurality of rectangular back electrodes 21 are arranged on the back surface of the p-type semiconductor substrate 10 so as to be separated from each other.
  • FIG. 3 is a plan view schematically showing another example of the back electrode arrangement in the semiconductor substrate on which the back electrode 21 is formed.
  • two rectangular back electrodes 21 are arranged on the back surface of the p-type semiconductor substrate 10 so that their long sides are parallel to each other.
  • the arrangement of the back electrode 21 in the present invention may be the embodiment shown in FIG. 2, the embodiment shown in FIG. 3, or any other embodiment that can achieve the effects of the present invention.
  • FIG. 4 is a plan view schematically showing an example of the arrangement of the light receiving surface electrodes in the p-type semiconductor substrate 10 on which the light receiving surface electrodes 20 are formed.
  • a light receiving surface bus bar electrode 50 and a light receiving surface finger electrode 51 may be formed.
  • L2 indicates the length of one side of the semiconductor substrate
  • L8 indicates the width of the light receiving surface bus bar electrode 50
  • L9 indicates the width of the light receiving surface finger electrode 51.
  • the width L8 of the light receiving surface bus bar electrode 50 is preferably 500 ⁇ m to 3 mm
  • the width L9 of the light receiving surface finger electrode 51 is preferably 10 ⁇ m to 400 ⁇ m.
  • FIG. 5 is an example of a plan view of the back surface of the semiconductor substrate in which the back electrode 21 and the passivation layer 19 are formed on the p-type semiconductor substrate 10.
  • a plurality of rectangular back electrodes 21 are arranged apart from each other, and a passivation layer 19 is formed in a region other than the back electrodes 21.
  • L1 indicates the length of one side of the region where the passivation layer 19 is formed
  • L2 indicates the length of one side of the p-type semiconductor substrate 10.
  • L3 and L4 each indicate the length of one side of the rectangular back electrode 21.
  • L3 and L4 are each preferably 10 ⁇ m to 156 mm.
  • FIG. 6 is another example of a plan view of the back surface of the semiconductor substrate in which the back electrode 21 and the passivation layer 19 are formed on the p-type semiconductor substrate 10.
  • two rectangular back electrodes 21 are arranged so that their long sides are parallel to each other, and a passivation layer 19 is formed in a region other than the back electrode 21.
  • L1 indicates the length of one side of the region where the passivation layer 19 is formed
  • L2 indicates the length of one side of the p-type semiconductor substrate 10.
  • L5 indicates the length of the short side of the rectangular back electrode 21.
  • L5 is preferably 50 ⁇ m to 10 mm.
  • L2 which is the length of one side of the p-type semiconductor substrate 10 is preferably 125 mm to 156 mm.
  • L1 which is the length of one side of the region where the passivation layer 19 is formed is preferably 100 ⁇ m to 156 mm.
  • the solar cell module of this invention has the solar cell element of this invention, and the wiring material arrange
  • the solar cell module may include a plurality of solar cell elements connected via a wiring material, and may be sealed with a sealing material.
  • the wiring material and the sealing material are not particularly limited, and can be appropriately selected from materials usually used in this technical field.
  • the size of the solar cell module is not particularly limited, and can be, for example, 0.5 m 2 to 3 m 2 .
  • Example 1> (Preparation of a composition for forming a passivation layer) Al 2 O 3 thin film coating material (High Purity Chemical Laboratory, SYM-Al04, Al 2 O 3 : 2% by mass, xylene: 87% by mass, 2-propanol: 5% by mass, stabilizer: 6% by mass 1.0 g), Nb 2 O 5 thin film coating material (High Purity Chemical Laboratory, Nb-05, Nb 2 O 5 : 5% by mass, n-butyl acetate: 56% by mass, stabilizer: 16.
  • the composition 1 for forming a passivation layer 1 was prepared by mixing 1.0 g of 5 mass%, viscosity modifier: 22.5 mass%).
  • a single crystal p-type silicon substrate (SUMCO, 50 mm square, thickness: 625 ⁇ m) having a mirror-shaped surface was used.
  • the silicon substrate was pre-treated by immersing and cleaning at 70 ° C. for 5 minutes using an RCA cleaning solution (Kanto Chemical Co., Ltd., Frontier Cleaner-A01). Thereafter, the entire surface of one surface of the silicon substrate pretreated with the composition 1 for forming a passivation layer obtained above was applied at 4000 rpm (min ⁇ 1 ) for 30 seconds using a spin coater (Mikasa Corporation, MS-100). Granted on condition. Then, it dried at 150 ° C. for 3 minutes. Next, after baking in air at 700 ° C. for 10 minutes, the substrate was allowed to cool at room temperature (25 ° C.) to produce an evaluation substrate having a passivation layer.
  • the effective lifetime ( ⁇ s) of the region where the passivation layer of the evaluation substrate obtained above is formed is reflected at a room temperature using a lifetime measurement device (Nippon Semi-Lab Co., Ltd., WT-2000PVN) at a room temperature. Measured by the method. The effective lifetime was 480 ⁇ s.
  • the thickness of the passivation layer was measured at five points in the plane using an interference film thickness meter (Filmetrics Co., Ltd., F20 film thickness measurement system), and the average value was calculated. The average value was 82 nm.
  • the density was calculated from the mass and average thickness of the passivation layer. The density was 3.2 g / cm 3 .
  • the particle shape of the obtained glass particles was substantially spherical, and the volume average particle size measured by a laser diffraction particle size distribution measuring device was 8 ⁇ m.
  • the volume average particle diameter was calculated based on the Mie scattering theory by detecting the relationship between the scattered light intensity and the angle of the laser light irradiated on the glass particles.
  • 0.1 g of glass particles dispersed in 10 g of terpineol (Nippon Terpene Chemical Co., Ltd., Terpineol-LW) was used as a measurement sample.
  • the n-type diffusion region forming composition was applied to a 156 mm square p-type silicon substrate (Advantech Co., Ltd., substrate specific resistance: 2 ⁇ ⁇ cm, thickness: 200 ⁇ m) by screen printing, It was dried on a hot plate at 150 ° C. for 1 minute. Thereafter, the p-type silicon substrate was placed on a quartz boat and placed in a 700 ° C. diffusion furnace (Koyo Thermo System Co., Ltd., 206A-M100). Next, the temperature was raised to 850 ° C. and held for 30 minutes to form a first impurity diffusion region (first n-type diffusion region).
  • the temperature was lowered to 820 ° C., and a second impurity diffusion region (second n-type diffusion region) was formed by treatment with POCl 3 gas. Specifically, after holding for 5 minutes at 820 ° C., flushed with 10 minutes POCl 3 gas, forming a second n-type diffusion region diffused by subsequent POCl 3 further drive-in phosphorous 10 minutes to stop the gas did. Next, the temperature was lowered to 700 ° C. and held at 700 ° C. for 1 hour. Thereafter, the quartz boat and the silicon substrate were taken out.
  • the composition 1 for forming a semiconductor substrate passivation layer obtained above was applied to an inkjet apparatus (Microjet Corporation, MJP-1500V, head: IJH) so that the composition layer had the pattern of the passivation layer 19 shown in FIG. ⁇ 80, nozzle size: 50 ⁇ m ⁇ 70 ⁇ m) and applied on the back surface of the p-type silicon substrate.
  • the reverse opening pattern (the opening 60 in FIG. 8) is different from the screen mask plate for forming the back electrode having the square opening 60 of 8 mm ⁇ 8 mm and the non-opening 61 shown in FIG.
  • an aluminum electrode paste (PVG solutions, PVG-AD-02) was screen-printed on the area where the back electrode was to be formed, using a screen mask plate for forming the back electrode having the pattern shown in FIG. And dried for 3 minutes.
  • a silver electrode paste (DuPont Co., Ltd., PV159A) is used by using a screen mask plate for forming a light receiving surface electrode having an opening with a bus bar width of 1.5 mm and a finger width of 150 ⁇ m as shown in FIG. Was screen-printed and dried at 150 ° C. for 3 minutes.
  • the power generation characteristics were evaluated using a solar cell element solar simulator (Wacom Denso Co., Ltd., XS-155S-10). Evaluation was made with simulated sunlight (device name: WXS-155S-10, Wacom Denso Co., Ltd.) and voltage-current (IV) evaluation measuring device (device name: IV CURVE TRACER MP-160, Eihiro Seiki) This was performed in combination with a measuring device of Co. Ltd.
  • Jsc short-circuit current density
  • Voc open circuit voltage
  • FF fill factor
  • Eff1 conversion efficiency indicating the power generation performance as a solar cell
  • Table 2 The evaluation was performed with a mask so that the light receiving area was 125 mm ⁇ 125 mm.
  • the produced solar cell element was put in a constant temperature and humidity chamber at 50 ° C. and 80% RH, and power generation characteristics after storage for 1 month were evaluated.
  • the results are shown in Table 3.
  • the conversion efficiency after storage of the solar electronic device was 98.7% of the conversion efficiency Eff2 before storage, and the conversion efficiency was reduced by 1.3%.
  • Example 2> (Preparation of a composition for forming a passivation layer)
  • Ta 2 O 5 thin film coating material High Purity Chemical Laboratory, Ta-10-P, Ta 2 O 5 : 10% by mass, n-octane: 9% by mass, n-butyl acetate: 60% by mass, stabilization Agent: 21% by mass) was used as composition 2 for forming a passivation layer.
  • a substrate for evaluation was prepared by forming a passivation layer on a pretreated silicon substrate in the same manner as in Example 1 except that the above-described composition 2 for forming a passivation layer was used. And evaluated. The effective lifetime was 450 ⁇ s.
  • the average thickness and density of the passivation layer were 75 nm and 3.6 g / cm 3 , respectively.
  • a solar cell element was produced in the same manner as in Example 1 except that the passivation layer forming composition 2 was used instead of the passivation layer forming composition 1, and the power generation characteristics were evaluated. The results are shown in Tables 2 and 3. The conversion efficiency after storage of the solar electronic device was 98.7% of the conversion efficiency before storage, and the conversion efficiency was reduced by 1.3%.
  • HfO 2 thin film coating material High Purity Chemical Laboratory, Hf-05, HfO 2 : 5% by mass, isoamyl acetate: 73% by mass, n-octane: 10% by mass, 2-propanol: 5% by mass, stabilized Agent: 7% by mass
  • HfO 2 thin film coating material High Purity Chemical Laboratory, Hf-05, HfO 2 : 5% by mass, isoamyl acetate: 73% by mass, n-octane: 10% by mass, 2-propanol: 5% by mass, stabilized Agent: 7% by mass
  • a substrate for evaluation was prepared by forming a passivation layer on a pretreated silicon substrate in the same manner as in Example 1 except that the composition 3 for forming a passivation layer prepared above was used. Evaluation was performed in the same manner. The effective lifetime was 380 ⁇ s. The average thickness and density of the passivation layer were 71 nm and 3.2 g / cm 3 , respectively.
  • a solar cell element was produced in the same manner as in Example 1 except that the passivation layer forming composition 3 was used instead of the passivation layer forming composition 1, and power generation characteristics were evaluated.
  • the results are shown in Tables 2 and 3.
  • the conversion efficiency after storage of the solar electronic device was 98.4% of the conversion efficiency before storage, and the conversion efficiency decreased by 1.6%.
  • Y 2 O 3 thin film coating material (High-Purity Chemical Laboratory, Y-03, Y 2 O 3 : 3% by mass, 2-ethylhexanoic acid: 12.5% by mass, n-butyl acetate: 22.5% by mass %, Ethyl acetate: 8% by mass, terpin oil: 45% by mass, viscosity modifier: 9% by mass) was used as the passivation layer forming composition 4.
  • a substrate for evaluation was prepared by forming a passivation layer on a pretreated silicon substrate in the same manner as in Example 1 except that the composition 4 for forming a passivation layer prepared above was used. Evaluation was performed in the same manner. The effective lifetime was 390 ⁇ s. The average thickness and density of the passivation layer were 68 nm and 2.8 g / cm 3 , respectively.
  • a solar cell element was produced in the same manner as in Example 1 except that the passivation layer forming composition 4 was used instead of the passivation layer forming composition 1, and the power generation characteristics were evaluated. The results are shown in Tables 2 and 3. The conversion efficiency after storage of the solar electronic device was 98.3% of the conversion efficiency before storage, and the conversion efficiency was reduced by 1.7%.
  • Example 5 Aluminum ethyl acetoacetate diisopropylate (Kawaken Fine Chemical Co., Ltd., ALCH), pentaethoxyniobium (Hokuko Chemical Co., Ltd.), acetylacetone (Wako Pure Chemical Industries, Ltd.), xylene (Wako Pure Chemical Industries, Ltd.), 2- Propanol (Wako Pure Chemical Industries, Ltd.) and terpineol (Nippon Terpene Chemical Co., Ltd.) were mixed so as to have the ratio shown in Table 1 and used as the passivation layer forming composition 5.
  • a substrate for evaluation was prepared by forming a passivation layer on a pretreated silicon substrate in the same manner as in Example 1 except that the composition 5 for forming a passivation layer prepared above was used. Evaluation was performed in the same manner. The effective lifetime was 420 ⁇ s. The average thickness and density of the passivation layer were 94 nm and 2.6 g / cm 3 , respectively.
  • a solar cell element was produced in the same manner as in Example 1 except that the passivation layer forming composition 5 was used instead of the passivation layer forming composition 1, and power generation characteristics were evaluated.
  • the results are shown in Tables 2 and 3.
  • the conversion efficiency after storage of the solar electronic device was 97.9% of the conversion efficiency before storage, and the conversion efficiency was reduced by 2.1%.
  • Example 6 In Example 1, instead of forming the aluminum electrode by the screen printing method, an aluminum vapor deposition machine (Sanyu Electronics Co., Ltd., SVC-700TM) was used to deposit aluminum with a solid pattern of 125 mm ⁇ 125 mm to form the back electrode. A substrate for evaluation and a solar cell element were produced in the same manner as in Example 1 except that. The aluminum vapor deposition was performed after the degree of vacuum became 10 ⁇ 4 Pa or less, and the distance between the substrate and the vapor deposition source was 70 mm and the treatment was performed for 5 minutes. The passivation layer was formed in a region other than the region where the 125 mm ⁇ 125 mm back electrode was formed before aluminum deposition.
  • SVC-700TM anyu Electronics Co., Ltd., SVC-700TM
  • Example 1 an evaluation substrate was prepared in the same manner as in Example 1 except that the passivation layer forming composition 1 was not applied, and evaluated in the same manner as in Example 1.
  • the effective lifetime was 20 ⁇ s.
  • Example 1 a solar cell element was produced in the same manner as in Example 1 except that the passivation layer forming composition 1 was not applied, and the power generation characteristics were evaluated. The results are shown in Tables 2 and 3. The conversion efficiency after storage of the solar electronic device was 93.0% of the conversion efficiency before storage, and the conversion efficiency was reduced by 7.0%.
  • a passivation layer was formed on a silicon substrate pretreated in the same manner as in Example 1 except that the composition C2 prepared above was used, and an evaluation substrate was produced. Evaluation was performed in the same manner as in Example 1. .
  • the effective lifetime was 21 ⁇ s.
  • the average thickness and density of the passivation layer were 2.1 ⁇ m and 1.4 g / cm 3 , respectively.
  • the average thickness of the passivation layer was measured with a stylus profilometer (Ambios, XP-2).
  • a part of the passivation layer was scraped off with a spatula, and a step between the portion where the passivation layer remained and the scraped portion was measured under the conditions of a speed of 0.1 mm / s and a needle load of 0.5 mg. The measurement was performed three times, and the average value was calculated as the film thickness.
  • a solar cell element was produced in the same manner as in Example 1 except that the composition C2 prepared above was used instead of the composition 1 for forming a passivation layer, and power generation characteristics were evaluated. The results are shown in Tables 2 and 3. The conversion efficiency after storage of the solar electronic device was 92.1% of the conversion efficiency before storage, and the conversion efficiency decreased by 7.9%.
  • a colorless and transparent composition C3 was prepared by mixing 2.01 g of tetraethoxysilane, 4.02 g of the 15 parts by mass ethylcellulose / terpineol solution prepared above and 3.97 g of terpineol.
  • a passivation layer was formed on a silicon substrate pretreated in the same manner as in Example 1 except that the composition C3 prepared above was used, and an evaluation substrate was produced. Evaluation was performed in the same manner as in Example 1. .
  • the effective lifetime was 23 ⁇ s.
  • the average thickness and density of the passivation layer were 85 nm and 2.1 g / cm 3 , respectively.
  • a solar cell element was produced in the same manner as in Example 1 except that the composition C3 prepared above was used instead of the passivation layer forming composition 1, and power generation characteristics were evaluated. The results are shown in Tables 2 and 3. The conversion efficiency after storage of the solar electronic device was 93.3% of the conversion efficiency before storage, and the conversion efficiency was reduced by 6.7%.
  • the solar cell element of the present invention has a passivation layer having an excellent passivation effect, and thus exhibits high conversion efficiency and suppresses deterioration of solar cell characteristics over time. Furthermore, it turns out that the passivation layer of the solar cell element of the present invention can be formed in a desired shape by a simple process.
  • a passivation film used for a solar cell element including aluminum oxide and niobium oxide and having a silicon substrate.
  • niobium oxide / aluminum oxide a mass ratio (niobium oxide / aluminum oxide) between the niobium oxide and the aluminum oxide is 30/70 to 90/10.
  • ⁇ 3> The passivation film according to ⁇ 1> or ⁇ 2>, in which a total content of the niobium oxide and the aluminum oxide is 90% by mass or more.
  • the passivation film according to any one of ⁇ 1> to ⁇ 4> which is a heat-treated product of a coating type material including an aluminum oxide precursor and a niobium oxide precursor.
  • a p-type silicon substrate made of single crystal silicon or polycrystalline silicon and having a light receiving surface and a back surface opposite to the light receiving surface;
  • An n-type impurity diffusion layer formed on the light-receiving surface side of the silicon substrate;
  • a first electrode formed on the surface of the n-type impurity diffusion layer on the light-receiving surface side of the silicon substrate;
  • a passivation film comprising aluminum oxide and niobium oxide formed on the back surface of the silicon substrate and having a plurality of openings;
  • a second electrode forming an electrical connection with the surface on the back side of the silicon substrate through the plurality of openings;
  • a solar cell element comprising:
  • a p-type silicon substrate made of single crystal silicon or polycrystalline silicon and having a light receiving surface and a back surface opposite to the light receiving surface;
  • An n-type impurity diffusion layer formed on the light-receiving surface side of the silicon substrate;
  • a first electrode formed on the surface of the n-type impurity diffusion layer on the light-receiving surface side of the silicon substrate;
  • a p-type impurity diffusion layer formed on a part or all of the back side of the silicon substrate and doped with impurities at a higher concentration than the silicon substrate;
  • a passivation film comprising aluminum oxide and niobium oxide formed on the back surface of the silicon substrate and having a plurality of openings;
  • a second electrode that forms an electrical connection with the surface of the p-type impurity diffusion layer on the back side of the silicon substrate through the plurality of openings;
  • a solar cell element comprising:
  • An n-type silicon substrate made of single crystal silicon or polycrystalline silicon and having a light receiving surface and a back surface opposite to the light receiving surface;
  • a p-type impurity diffusion layer formed on the light-receiving surface side of the silicon substrate;
  • a second electrode formed on the back side of the silicon substrate;
  • a passivation film formed on the light-receiving surface side surface of the silicon substrate and including a plurality of openings and containing aluminum oxide and niobium oxide;
  • a first electrode formed on the surface of the p-type impurity diffusion layer on the light-receiving surface side of the silicon substrate and forming an electrical connection with the surface on the light-receiving surface side of the silicon substrate through the plurality of openings;
  • a solar cell element comprising:
  • ⁇ 10> The solar cell element according to any one of ⁇ 7> to ⁇ 9>, wherein a mass ratio of niobium oxide to aluminum oxide (niobium oxide / aluminum oxide) in the passivation film is 30/70 to 90/10.
  • ⁇ 11> The solar cell element according to any one of ⁇ 7> to ⁇ 10>, wherein a total content of the niobium oxide and the aluminum oxide in the passivation film is 90% by mass or more.
  • ⁇ 12> a silicon substrate;
  • a passivation film having a long carrier lifetime of a silicon substrate and having a negative fixed charge can be realized at low cost.
  • a coating type material for realizing the formation of the passivation film can be provided.
  • a highly efficient solar cell element using the passivation film can be realized at low cost.
  • a silicon substrate with a passivation film having a long carrier lifetime and a negative fixed charge can be realized at low cost.
  • the passivation film of the present embodiment is a passivation film used for a silicon solar cell element, and includes aluminum oxide and niobium oxide.
  • the fixed charge amount of the film can be controlled by changing the composition of the passivation film.
  • the mass ratio of niobium oxide and aluminum oxide is 30/70 to 80/20 from the viewpoint that the negative fixed charge can be stabilized. Further, the mass ratio of niobium oxide and aluminum oxide is more preferably 35/65 to 70/30 from the viewpoint that the negative fixed charge can be further stabilized. Further, the mass ratio of niobium oxide and aluminum oxide is preferably 50/50 to 90/10 from the viewpoint that both improvement of carrier lifetime and negative fixed charge can be achieved.
  • the mass ratio of niobium oxide to aluminum oxide in the passivation film is measured by energy dispersive X-ray spectroscopy (EDX), secondary ion mass spectrometry (SIMS), and high frequency inductively coupled plasma mass spectrometry (ICP-MS). be able to.
  • Specific measurement conditions are as follows. Dissolving the passivation film in acid or alkaline aqueous solution, atomizing this solution and introducing it into Ar plasma, measuring the wavelength and intensity by spectroscopically analyzing the light emitted when the excited element returns to the ground state, Element qualification is performed from the obtained wavelength, and quantification is performed from the obtained intensity.
  • the total content of niobium oxide and aluminum oxide in the passivation film is preferably 80% by mass or more, and more preferably 90% by mass or more from the viewpoint of maintaining good characteristics. As the components of niobium oxide and aluminum oxide in the passivation film increase, the effect of negative fixed charges increases.
  • the total content of niobium oxide and aluminum oxide in the passivation film can be measured by combining thermogravimetric analysis, fluorescent X-ray analysis, ICP-MS, and X-ray absorption spectroscopy. Specific measurement conditions are as follows.
  • the ratio of inorganic components can be calculated by thermogravimetric analysis, the ratio of niobium and aluminum can be calculated by fluorescent X-ray or ICP-MS analysis, and the ratio of oxide can be examined by X-ray absorption spectroscopy.
  • components other than niobium oxide and aluminum oxide may be included as organic components from the viewpoint of improving the film quality and adjusting the elastic modulus.
  • the presence of the organic component in the passivation film can be confirmed by elemental analysis and measurement of the FT-IR of the film.
  • the content of the organic component in the passivation film is more preferably less than 10% by mass, further preferably 5% by mass or less, and particularly preferably 1% by mass or less in the passivation film.
  • the passivation film may be obtained as a heat-treated product of a coating type material containing an aluminum oxide precursor and a niobium oxide precursor. Details of the coating type material will be described next.
  • the coating material of the present embodiment includes an aluminum oxide precursor and a niobium oxide precursor, and is used for forming a passivation film for a solar cell element having a silicon substrate.
  • the aluminum oxide precursor can be used without particular limitation as long as it produces aluminum oxide.
  • As the aluminum oxide precursor it is preferable to use an organic aluminum oxide precursor from the viewpoint of uniformly dispersing aluminum oxide on the silicon substrate and chemically stable.
  • organic aluminum oxide precursors include aluminum triisopropoxide (structural formula: Al (OCH (CH 3 ) 2 ) 3 , High Purity Chemical Research Laboratory SYM-AL04, and the like.
  • the niobium oxide precursor can be used without particular limitation as long as it produces niobium oxide.
  • the niobium oxide precursor it is preferable to use an organic niobium oxide precursor from the viewpoint of uniformly dispersing niobium oxide on the silicon substrate and chemically stable.
  • organic niobium oxide precursors include niobium (V) ethoxide (structural formula: Nb (OC 2 H 5 ) 5 , molecular weight: 318.21), High Purity Chemical Laboratory Nb-05, etc. be able to.
  • a passivation film is formed by forming a coating type material containing an organic niobium oxide precursor and an organic aluminum oxide precursor using a coating method or a printing method, and then removing organic components by a subsequent heat treatment (firing). Can be obtained. Therefore, as a result, a passivation film containing an organic component may be used.
  • FIGS. 10 to FIG. 13 are cross-sectional views showing first to fourth configuration examples of the solar cell element using the passivation film on the back surface of the present embodiment.
  • silicon substrate (crystalline silicon substrate, semiconductor substrate) 101 used in this embodiment mode either single crystal silicon or polycrystalline silicon may be used. Further, as the silicon substrate 101, either p-type crystalline silicon or n-type crystalline silicon may be used. From the standpoint of exerting the effects of the present embodiment, p-type crystalline silicon is more suitable.
  • the single crystal silicon or polycrystalline silicon used for the silicon substrate 101 may be arbitrary, but single crystal silicon or polycrystalline silicon having a resistivity of 0.5 ⁇ ⁇ cm to 10 ⁇ ⁇ cm is preferable.
  • a light receiving surface antireflection film 103 such as a silicon nitride (SiN) film, and a first electrode 105 (light receiving surface side electrode, first surface electrode, upper surface electrode) using silver (Ag) or the like. , A light receiving surface electrode) is formed.
  • the light receiving surface antireflection film 103 may also have a function as a light receiving surface passivation film. By using the SiN film, both functions of the light receiving surface antireflection film and the light receiving surface passivation film can be provided.
  • the solar cell element of the present embodiment may or may not have the light-receiving surface antireflection film 103.
  • the light receiving surface of the solar cell element is preferably formed with a concavo-convex structure (texture structure) in order to reduce the reflectance on the surface, but the solar cell element of the present embodiment has a texture structure. It may or may not have.
  • a BSF (Back Surface Field) layer 104 which is a layer doped with a group III element such as aluminum or boron, is formed on the back side (lower side, second side, back side in the figure) of the silicon substrate 101.
  • the solar cell element of this embodiment may or may not have the BSF layer 104.
  • a second surface made of aluminum or the like is used on the back surface side of the silicon substrate 101 to make contact (electrical connection) with the BSF layer 104 (or the surface on the back surface side of the silicon substrate 101 when the BSF layer 104 is not provided). Electrodes 106 (back side electrode, second side electrode, back side electrode) are formed.
  • a contact region (a surface on the back surface side of the silicon substrate 101 when the BSF layer 104 is not provided) and the second electrode 106 are electrically connected.
  • a passivation film (passivation layer) 107 containing aluminum oxide and niobium oxide is formed in a portion excluding the opening OA).
  • the passivation film 107 of this embodiment can have a negative fixed charge. With this fixed charge, electrons which are minority carriers among the carriers generated in the silicon substrate 101 by light are bounced back to the surface side. For this reason, a short circuit current increases and it is anticipated that photoelectric conversion efficiency will improve.
  • the second electrode 106 is formed on the entire surface of the contact region (opening OA) and the passivation film 107.
  • the second electrode 106 is formed only in the region (opening OA).
  • the second electrode 106 may be formed only in part on the contact region (opening OA) and the passivation film 107. Even with the solar cell element having the configuration shown in FIG. 11, the same effect as in FIG. 10 (first configuration example) can be obtained.
  • the BSF layer 104 is formed only on a part of the back surface side including the contact region (opening OA portion) with the second electrode 106, and FIG. 10 (first configuration example). Thus, it is not formed on the entire back surface side. Even with the solar cell element having such a configuration (FIG. 12), the same effect as in FIG. 10 (first configuration example) can be obtained. Further, according to the solar cell element of the third configuration example of FIG. 12, the BSF layer 104, that is, the impurity is doped at a higher concentration than the silicon substrate 101 by doping a group III element such as aluminum or boron. Since the area is small, it is possible to obtain higher photoelectric conversion efficiency than that in FIG. 10 (first configuration example).
  • FIG. 13 a fourth configuration example shown in FIG. 13 will be described.
  • the second electrode 106 is formed on the entire surface of the contact region (opening OA) and the passivation film 107, but in FIG. 13 (fourth configuration example), the contact is formed.
  • the second electrode 106 is formed only in the region (opening OA).
  • the second electrode 106 may be formed only in part on the contact region (opening OA) and the passivation film 107. Even with the solar cell element having the configuration shown in FIG. 13, the same effect as in FIG. 12 (third configuration example) can be obtained.
  • the second electrode 106 when the second electrode 106 is applied by a printing method and baked at a high temperature to form the entire surface on the back side, a convex warpage tends to occur in the temperature lowering process. Such warpage may cause damage to the solar cell element, which may reduce the yield. Further, the problem of warpage increases as the silicon substrate becomes thinner. The cause of this warp is that stress is generated because the thermal expansion coefficient of the second electrode 106 made of metal (for example, aluminum) is larger than that of the silicon substrate, and the shrinkage in the temperature lowering process is correspondingly large.
  • metal for example, aluminum
  • the electrode structure tends to be symmetrical vertically. This is preferable because stress due to the difference in thermal expansion coefficient is unlikely to occur. However, in that case, it is preferable to provide a separate reflective layer.
  • a texture structure is formed on the surface of the silicon substrate 101 shown in FIG.
  • the texture structure may be formed on both sides of the silicon substrate 101 or only on one side (light receiving side).
  • the damaged layer of the silicon substrate 101 is removed by immersing the silicon substrate 101 in a heated potassium hydroxide or sodium hydroxide solution.
  • a texture structure is formed on both surfaces or one surface (light receiving surface side) of the silicon substrate 101 by dipping in a solution containing potassium hydroxide and isopropyl alcohol as main components. Note that, as described above, the solar cell element of the present embodiment may or may not have a texture structure, and thus this step may be omitted.
  • a phosphorus diffusion layer (n + layer) is formed as the diffusion layer 102 by thermal diffusion of phosphorus oxychloride (POCl 3 ) or the like on the silicon substrate 101.
  • the phosphorus diffusion layer can be formed, for example, by applying a coating-type doping material solution containing phosphorus to the silicon substrate 101 and performing heat treatment. After the heat treatment, the phosphorous glass layer formed on the surface is removed with an acid such as hydrofluoric acid, whereby a phosphorous diffusion layer (n + layer) is formed as the diffusion layer 102.
  • the method for forming the phosphorus diffusion layer is not particularly limited.
  • the phosphorus diffusion layer may be formed so that the depth from the surface of the silicon substrate 101 is in the range of 0.2 ⁇ m to 0.5 ⁇ m, and the sheet resistance is in the range of 40 ⁇ / ⁇ to 100 ⁇ / ⁇ (ohm / square). preferable.
  • a BSF layer 104 on the back surface side is formed by applying a coating-type doping material solution containing boron, aluminum or the like to the back surface side of the silicon substrate 101 and performing heat treatment.
  • a coating-type doping material solution containing boron, aluminum or the like for the application, methods such as screen printing, inkjet, dispensing, spin coating and the like can be used.
  • the BSF layer 104 is formed by removing a layer of boron glass, aluminum, or the like formed on the back surface with hydrofluoric acid, hydrochloric acid, or the like.
  • the method for forming the BSF layer 104 is not particularly limited.
  • the BSF layer 104 is formed so that the concentration range of boron, aluminum, etc.
  • the solar cell element of the present embodiment may or may not have the BSF layer 104, and thus this step may be omitted.
  • the diffusion layer 102 on the light-receiving surface and the BSF layer 104 on the back surface are formed using a coating-type doping material solution
  • the above-described doping material solution is applied to both sides of the silicon substrate 101 to diffuse.
  • the phosphorous diffusion layer (n + layer) and the BSF layer 104 as the layer 102 may be formed in a lump, and then phosphorous glass, boron glass, or the like formed on the surface may be removed all at once.
  • a silicon nitride film as the light-receiving surface antireflection film 103 is formed on the diffusion layer 102.
  • the method for forming the light receiving surface antireflection film 103 is not particularly limited.
  • the light-receiving surface antireflection film 103 is preferably formed to have a thickness in the range of 50 to 100 nm and a refractive index in the range of 1.9 to 2.2.
  • the light-receiving surface antireflection film 103 is not limited to a silicon nitride film, and may be a silicon oxide film, an aluminum oxide film, a titanium oxide film, or the like.
  • the surface antireflection film 103 such as an silicon nitride film can be formed by a method such as plasma CVD or thermal CVD, and is preferably formed by plasma CVD that can be formed in a temperature range of 350 ° C. to 500 ° C.
  • the passivation film 107 contains aluminum oxide and niobium oxide.
  • an aluminum oxide precursor typified by an organometallic decomposition coating material from which aluminum oxide can be obtained by heat treatment (firing), and niobium oxide obtained by heat treatment (firing). It is formed by applying a material (passivation material) containing a niobium oxide precursor typified by a commercially available organometallic decomposition coating type material and heat-treating (firing).
  • the formation of the passivation film 107 can be performed as follows, for example.
  • the above coating material is spin-coated on one side of a 725 ⁇ m thick 8-inch (20.32 cm) p-type silicon substrate (8 ⁇ cm to 12 ⁇ cm) from which a natural oxide film has been previously removed with hydrofluoric acid having a concentration of 0.049% by mass
  • pre-baking is performed on a hot plate at 120 ° C. for 3 minutes. Thereafter, heat treatment is performed at 650 ° C. for 1 hour in a nitrogen atmosphere. In this case, a passivation film containing aluminum oxide and niobium oxide is obtained.
  • the thickness of the passivation film 107 formed by the above method is usually about several tens of nanometers as measured by an ellipsometer.
  • the coating type material is applied to a predetermined pattern including the contact area (opening OA) by a method such as screen printing, offset printing, inkjet printing, or dispenser printing.
  • the above-mentioned coating type material is pre-baked in the range of 80 ° C. to 180 ° C. after evaporation to evaporate the solvent, and then at 600 ° C. to 1000 ° C. for 30 minutes to 3 hours in a nitrogen atmosphere or in air. It is preferable to perform a degree of heat treatment (annealing) to form a passivation film 107 (oxide film).
  • the opening (contact hole) OA is preferably formed in a dot shape or a line shape on the BSF layer 104.
  • the mass ratio of niobium oxide to aluminum oxide is preferably 30/70 to 90/10, and preferably 30/70 to 80/20. More preferably, it is more preferably 35/65 to 70/30. Thereby, the negative fixed charge can be stabilized. Further, the mass ratio of niobium oxide and aluminum oxide is preferably 50/50 to 90/10 from the viewpoint that both improvement of carrier lifetime and negative fixed charge can be achieved.
  • the total content of niobium oxide and aluminum oxide is preferably 80% by mass or more, and more preferably 90% by mass or more.
  • the first electrode 105 which is an electrode on the light receiving surface side is formed.
  • the first electrode 105 is formed by forming a paste mainly composed of silver (Ag) on the light-receiving surface antireflection film 103 by screen printing and performing a heat treatment (fire through).
  • the shape of the 1st electrode 105 may be arbitrary shapes, for example, may be a known shape which consists of a finger electrode and a bus-bar electrode.
  • the second electrode 106 which is an electrode on the back side is formed.
  • the second electrode 106 can be formed by applying a paste containing aluminum as a main component using screen printing or a dispenser and heat-treating it.
  • the shape of the second electrode 106 is preferably the same shape as the shape of the BSF layer 104, a shape covering the entire back surface, a comb shape, a lattice shape, or the like.
  • the paste for forming the first electrode 105 and the second electrode 106, which are the electrodes on the light receiving surface side, is first printed, and then heat-treated (fire-through), whereby the first electrode 105 and the second electrode 106 are formed.
  • the two electrodes 106 may be formed together.
  • the BSF layer 104 is formed in a contact portion between the second electrode 106 and the silicon substrate 101 in a self-alignment manner. Is formed.
  • the BSF layer 104 may be separately formed by applying a coating-type doping material solution containing boron, aluminum, or the like to the back side of the silicon substrate 101 and heat-treating it. .
  • the diffusion layer 102 is formed by a layer doped with a group III element such as boron
  • the BSF layer 104 is formed by doping a group V element such as phosphorus.
  • a leakage current flows through a portion where the inversion layer formed at the interface due to the negative fixed charge and the metal on the back surface are in contact with each other, and the conversion efficiency may be difficult to increase.
  • FIG. 14 is a cross-sectional view showing a configuration example of a solar cell element using the light-receiving surface passivation film of the present embodiment.
  • the diffusion layer 102 on the light receiving surface side is p-type doped with boron, and collects holes on the light receiving surface side and electrons on the back surface side of the generated carriers. For this reason, it is preferable that the passivation film 107 having a negative fixed charge is on the light receiving surface side.
  • an antireflection film made of SiN or the like may be further formed by CVD or the like.
  • the passivation material (a-1) is spin-coated on one side of a 725 ⁇ m-thick 8-inch p-type silicon substrate (8 ⁇ cm to 12 ⁇ cm) from which a natural oxide film has been removed in advance with a hydrofluoric acid having a concentration of 0.049% by mass.
  • Pre-baking was performed on the plate at 120 ° C. for 3 minutes.
  • the FT-IR of the passivation film was measured, a very few peaks due to alkyl groups were observed in the vicinity of 1200 cm ⁇ 1 .
  • a plurality of aluminum electrodes having a diameter of 1 mm were formed on the above-described passivation film through a metal mask by vapor deposition, thereby manufacturing a capacitor having a metal-insulator-semiconductor (MIS) structure.
  • the voltage dependence (CV characteristics) of the capacitance of this capacitor was measured with a commercially available prober and LCR meter (HP, 4275A). As a result, it was found that the flat band voltage (Vfb) shifted from an ideal value of ⁇ 0.81V to + 0.32V. From this shift amount, it was found that the passivation film obtained from the passivation material (a-1) showed a negative fixed charge with a fixed charge density (Nf) of ⁇ 7.4 ⁇ 10 11 cm ⁇ 2 .
  • the passivation material (a-1) is applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and subjected to a heat treatment (firing) at 650 ° C. for 1 hour in a nitrogen atmosphere.
  • a sample in which both surfaces of the substrate were covered with a passivation film was produced.
  • the carrier lifetime of this sample was measured using a lifetime measuring device (Kobelco Research Institute, Inc., RTA-540). As a result, the carrier lifetime was 530 ⁇ s.
  • the same 8-inch p-type silicon substrate was measured by passivation using the iodine passivation method, and the carrier lifetime was 1100 ⁇ s.
  • the passivation film obtained by heat-treating (firing) the passivation material (a-1) showed a certain degree of passivation performance and a negative fixed charge.
  • Reference Example 1-2 Similar to Reference Example 1-1, a commercially available organometallic decomposition coating material from which aluminum oxide (Al 2 O 3 ) can be obtained by heat treatment (calcination) [High-Purity Chemical Laboratory, SYM-AL04, concentration 2. 3 mass%] and a commercially available organometallic decomposable coating type material [High Purity Chemical Laboratory, Nb-05, concentration 5 mass%] from which niobium oxide (Nb 2 O 5 ) can be obtained by heat treatment (firing). Passivation materials (a-2) to (a-7) shown in Table 4 were prepared by mixing at different ratios.
  • each of the passivation materials (a-2) to (a-7) was applied to one side of a p-type silicon substrate, and heat treatment (firing) was performed to produce a passivation film.
  • the voltage dependence of the capacitance of the obtained passivation film was measured, and the fixed charge density was calculated therefrom.
  • the carrier lifetime is also increased after heat treatment (firing). Since it showed a certain value, it was suggested that it functions as a passivation film. It was found that all the passivation films obtained from the passivation materials (a-2) to (a-7) stably show negative fixed charges and can be suitably used as a passivation for a p-type silicon substrate. .
  • the passivation material (c-1) is spin-coated on one side of a 725 ⁇ m-thick 8-inch p-type silicon substrate (8 ⁇ cm to 12 ⁇ cm) from which a natural oxide film has been removed in advance with a hydrofluoric acid having a concentration of 0.049% by mass.
  • Pre-baking was performed at 120 ° C. for 3 minutes on the plate.
  • heat treatment was performed at 600 ° C. for 1 hour in a nitrogen atmosphere to obtain a passivation film containing aluminum oxide and niobium oxide. When the film thickness was measured with an ellipsometer, it was 50 nm.
  • a plurality of aluminum electrodes having a diameter of 1 mm were formed on the above-described passivation film through a metal mask by vapor deposition, thereby manufacturing a capacitor having a metal-insulator-semiconductor (MIS) structure.
  • the voltage dependence (CV characteristics) of the capacitance of this capacitor was measured with a commercially available prober and LCR meter (HP, 4275A). As a result, it was found that the flat band voltage (Vfb) shifted from an ideal value of ⁇ 0.81 V to +4.7 V. From this shift amount, it was found that the passivation film obtained from the passivation material (c-1) showed a negative fixed charge with a fixed charge density (Nf) of ⁇ 3.2 ⁇ 10 12 cm ⁇ 2 .
  • the passivation material (c-1) was applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and subjected to heat treatment (baking) at 600 ° C. for 1 hour in a nitrogen atmosphere to obtain silicon.
  • a sample in which both surfaces of the substrate were covered with a passivation film was produced.
  • the carrier lifetime of this sample was measured using a lifetime measuring device (Kobelco Research Institute, Inc., RTA-540). As a result, the carrier lifetime was 330 ⁇ s.
  • the same 8-inch p-type silicon substrate was measured by passivation using the iodine passivation method, and the carrier lifetime was 1100 ⁇ s.
  • the passivation film obtained by heat-treating (sintering) the passivation material (c-1) exhibited a certain degree of passivation performance and a negative fixed charge.
  • the passivation material (c-2) is spin-coated on one side of a 725 ⁇ m-thick 8-inch p-type silicon substrate (8 ⁇ cm to 12 ⁇ cm) from which a natural oxide film has been removed in advance with a hydrofluoric acid having a concentration of 0.049% by mass.
  • Pre-baking was performed at 120 ° C. for 3 minutes on the plate.
  • heat treatment was performed at 600 ° C. for 1 hour in a nitrogen atmosphere to obtain a passivation film containing aluminum oxide and niobium oxide. When the film thickness was measured by an ellipsometer, it was 14 nm.
  • a plurality of 1 mm diameter aluminum electrodes are deposited on the passivation film through a metal mask to form a MIS (Metal-Insulator-Semiconductor) capacitor.
  • the voltage dependence (CV characteristics) of the capacitance of this capacitor was measured with a commercially available prober and LCR meter (HP, 4275A).
  • Vfb flat band voltage
  • LCR meter HP, 4275A
  • Vfb flat band voltage
  • the passivation film obtained from the passivation material (c-2) showed a negative fixed charge with a fixed charge density (Nf) of ⁇ 0.8 ⁇ 10 11 cm ⁇ 2 .
  • the passivation material (c-2) is applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and subjected to heat treatment (firing) at 600 ° C. for 1 hour in a nitrogen atmosphere.
  • a sample in which both surfaces of the substrate were covered with a passivation film was produced.
  • the carrier lifetime of this sample was measured with a lifetime measuring device (Kobelco Research Institute Co., Ltd., RTA-540). As a result, the carrier lifetime was 200 ⁇ s.
  • the same 8-inch p-type silicon substrate was measured by passivation using the iodine passivation method, and the carrier lifetime was 1100 ⁇ s.
  • each of the passivation materials (b-1) to (b-7) was applied to one side of a p-type silicon substrate and heat-treated (fired) to produce a passivation film, Using this, the voltage dependence of the capacitance was measured, and the fixed charge density was calculated therefrom.
  • the passivation film obtained from the passivation materials (b-1) to (b-6) has a large carrier lifetime and has a function as a passivation.
  • the niobium oxide / aluminum oxide ratios were 10/90 and 20/80, the fixed charge density values varied greatly, and a negative fixed charge density could not be stably obtained. It was confirmed that a negative fixed charge density can be realized by using niobium oxide.
  • a negative fixed charge is stably generated because a passivation film showing a positive fixed charge is obtained in some cases. It turns out that it has not reached to show.
  • a passivation film exhibiting a fixed charge can be used as a passivation for an n-type silicon substrate.
  • a negative fixed charge density could not be obtained with the passivation material (b-7) containing 100% by mass of aluminum oxide.
  • a passivation material (d-3) As a passivation material (d-3), a commercially available organometallic decomposition coating material [having high purity chemical laboratory Hf-05, concentration 5 mass%] from which hafnium oxide (HfO 2 ) can be obtained by heat treatment (firing) is used. Got ready.
  • each of the passivation materials (d-1) to (d-3) is applied to one side of a p-type silicon substrate, and then heat-treated (fired) to produce a passivation film. Using this, the voltage dependence of the capacitance was measured, and the fixed charge density was calculated therefrom.
  • the passivation films obtained from the passivation materials (d-1) to (d-3) have a small carrier lifetime and an insufficient function as a passivation. It also showed a positive fixed charge.
  • the passivation film obtained from the passivation material (d-3) had a negative fixed charge, but its value was small. It was also found that the carrier lifetime was relatively small and the function as a passivation was insufficient.
  • an SiN film produced by plasma CVD was formed as the light-receiving surface antireflection film 103 on the light-receiving surface side.
  • the passivation material (a-1) prepared in Reference Example 1-1 was applied to the region excluding the contact region (opening OA) on the back surface side of the silicon substrate 101 by the inkjet method. Thereafter, heat treatment was performed to form a passivation film 107 having an opening OA.
  • a sample using the passivation material (c-1) prepared in Reference Example 1-3 was separately prepared as the passivation film 107.
  • a paste mainly composed of silver was screen-printed in the shape of predetermined finger electrodes and bus bar electrodes.
  • a paste mainly composed of aluminum was screen-printed on the entire surface.
  • heat treatment fire-through
  • electrodes first electrode 105 and second electrode 106
  • aluminum is diffused into the opening OA on the back surface to form the BSF layer 104.
  • the fire-through process in which the SiN film is not perforated is described, but the opening OA is first formed in the SiN film by etching or the like, and then the silver electrode is formed. You can also.
  • the passivation film 107 is not formed in the above manufacturing process, aluminum paste is printed on the entire back surface, and the p + layer 114 corresponding to the BSF layer 104 and the electrode 116 corresponding to the second electrode.
  • the characteristic evaluation was performed on the entire surface to form a solar cell element having the structure shown in FIG.
  • characteristic evaluation was performed according to JIS-C-8913 (fiscal 2005) and JIS-C-8914 (fiscal 2005). The results are shown in Table 7.
  • the solar cell element having the passivation film 107 including the niobium oxide and aluminum oxide layers has both increased short-circuit current and open-circuit voltage as compared with the solar cell element not having the passivation film 107, and the conversion efficiency ( It was found that the photoelectric conversion efficiency was improved by 1% at the maximum.
  • a passivation film for use in a solar cell element having a silicon substrate comprising aluminum oxide and an oxide of at least one vanadium group element selected from the group consisting of vanadium oxide and tantalum oxide.
  • ⁇ 2> The passivation film according to ⁇ 1>, wherein a mass ratio of the oxide of the vanadium group element to the aluminum oxide (vanadium group element oxide / aluminum oxide) is 30/70 to 90/10.
  • ⁇ 3> The passivation film according to ⁇ 1> or ⁇ 2>, in which a total content of the oxide of the vanadium group element and the aluminum oxide is 90% or more.
  • the oxide of the vanadium group element includes any of oxides of two or three kinds of vanadium group elements selected from the group consisting of vanadium oxide, niobium oxide, and tantalum oxide. Any one of ⁇ 1> to ⁇ 3> The passivation film according to claim 1.
  • ⁇ 5> Heat treatment of a coating-type material comprising: a precursor of aluminum oxide; and a precursor of an oxide of at least one vanadium group element selected from the group consisting of a precursor of vanadium oxide and a precursor of tantalum oxide.
  • the said passivation film is a solar cell element containing aluminum oxide and the oxide of the at least 1 sort (s) of vanadium group element selected from the group which consists of vanadium oxide and a tantalum oxide.
  • a p-type impurity diffusion layer formed on part or all of the second surface side of the silicon substrate and doped with an impurity at a higher concentration than the silicon substrate,
  • the said passivation film is a solar cell element containing aluminum oxide and the oxide of the at least 1 sort (s) of vanadium group element selected from the group which consists of vanadium oxide and a tantalum oxide.
  • n-type impurity diffusion layer formed on a part or all of the second surface side of the silicon substrate and doped with impurities at a higher concentration than the silicon substrate, The solar cell element according to ⁇ 9>, wherein the second electrode is electrically connected to the n-type impurity diffusion layer through an opening of the passivation film.
  • ⁇ 11> The solar cell element according to any one of ⁇ 7> to ⁇ 10>, wherein a mass ratio of the oxide of the vanadium group element and the aluminum oxide in the passivation film is 30/70 to 90/10 .
  • ⁇ 12> The solar cell element according to any one of ⁇ 7> to ⁇ 11>, wherein the total content of the oxide of the vanadium group element and the aluminum oxide in the passivation film is 90% or more.
  • the oxide of the vanadium group element includes an oxide of two or three vanadium group elements selected from the group consisting of vanadium oxide, niobium oxide, and tantalum oxide, ⁇ 7> to ⁇ 12>
  • the solar cell element according to any one of the above.
  • ⁇ 14> a silicon substrate;
  • a passivation film having a long carrier lifetime of a silicon substrate and having a negative fixed charge can be realized at low cost.
  • a coating type material for realizing the formation of the passivation film can be provided.
  • a low-cost and highly efficient solar cell element using the passivation film can be realized.
  • a silicon substrate with a passivation film having a long carrier lifetime and a negative fixed charge can be realized at low cost.
  • the passivation film of the present embodiment is a passivation film used for a silicon solar cell element, and includes aluminum oxide and an oxide of at least one vanadium group element selected from the group consisting of vanadium oxide and tantalum oxide. It is what was included.
  • the amount of fixed charges possessed by the passivation film can be controlled by changing the composition of the passivation film.
  • the vanadium group element is a Group 5 element in the periodic table, and is an element selected from vanadium, niobium, and tantalum.
  • the mass ratio of the oxide of vanadium group element to aluminum oxide is preferably 35/65 to 90/10, from the viewpoint that the negative fixed charge can be stabilized, and is preferably 50/50 to 90/10. More preferably.
  • the mass ratio of vanadium group element oxide and aluminum oxide in the passivation film is determined by energy dispersive X-ray spectroscopy (EDX), secondary ion mass spectrometry (SIMS), and high frequency inductively coupled plasma mass spectrometry (ICP-MS). ) Can be measured. Specific measurement conditions are as follows in the case of ICP-MS, for example. Dissolving the passivation film in acid or alkaline aqueous solution, atomizing this solution and introducing it into Ar plasma, measuring the wavelength and intensity by spectroscopically analyzing the light emitted when the excited element returns to the ground state, Element qualification is performed from the obtained wavelength, and quantification is performed from the obtained intensity.
  • EDX energy dispersive X-ray spectroscopy
  • SIMS secondary ion mass spectrometry
  • ICP-MS high frequency inductively coupled plasma mass spectrometry
  • the total content of the vanadium group element oxide and aluminum oxide in the passivation film is preferably 80% by mass or more, and more preferably 90% by mass or more from the viewpoint of maintaining good characteristics.
  • the components other than the oxide of vanadium group elements and aluminum oxide in the passivation film increase, the effect of negative fixed charges increases.
  • components other than vanadium group oxide and aluminum oxide may be contained as organic components from the viewpoint of improving the film quality and adjusting the elastic modulus.
  • the presence of the organic component in the passivation film can be confirmed by elemental analysis and measurement of the FT-IR of the film.
  • vanadium oxide As the oxide of the vanadium group element, it is preferable to select vanadium oxide (V 2 O 5 ) from the viewpoint of obtaining a larger negative fixed charge.
  • the passivation film may include two or three vanadium group oxides selected from the group consisting of vanadium oxide, niobium oxide, and tantalum oxide as the vanadium group element oxide.
  • the passivation film is preferably obtained by heat-treating a coating-type material, and can be obtained by forming a coating-type material using a coating method or a printing method, and then removing organic components by heat treatment. More preferred. That is, the passivation film may be obtained as a heat-treated product of a coating type material containing an aluminum oxide precursor and a vanadium group element oxide precursor. Details of the coating type material will be described later.
  • the coating type material of the present embodiment is a coating type material used for a passivation film for a solar cell element having a silicon substrate, and includes a precursor of aluminum oxide, a precursor of vanadium oxide, and a precursor of tantalum oxide. And a precursor of an oxide of at least one vanadium group element selected from the group.
  • a precursor of the oxide of the vanadium group element contained in the coating material a precursor of vanadium oxide (V 2 O 5 ) is selected from the viewpoint of the negative fixed charge of the passivation film formed from the coating material. It is preferable.
  • the coating type material is composed of two or three vanadium group elements selected from the group consisting of vanadium oxide precursors, niobium oxide precursors and tantalum oxide precursors as vanadium group oxide precursors. An oxide precursor may also be included.
  • the aluminum oxide precursor can be used without particular limitation as long as it produces aluminum oxide.
  • As the aluminum oxide precursor it is preferable to use an organic aluminum oxide precursor from the viewpoint of uniformly dispersing aluminum oxide on the silicon substrate and a chemically stable viewpoint.
  • Examples of the organic aluminum oxide precursor include aluminum triisopropoxide (structural formula: Al (OCH (CH 3 ) 2 ) 3 , Kojundo Chemical Laboratory Co., Ltd., SYM-AL04.
  • the precursor of the oxide of the vanadium group element can be used without particular limitation as long as it generates an oxide of the vanadium group element.
  • the vanadium group element oxide precursor is preferably an organic vanadium group oxide oxide precursor from the viewpoint of uniformly dispersing aluminum oxide on the silicon substrate and chemically stable. .
  • organic vanadium oxide precursors examples include vanadium (V) oxytriethoxide (structural formula: VO (OC 2 H 5 ) 3 , molecular weight: 202.13), High Purity Chemical Laboratory, V-02 can be mentioned.
  • organic tantalum oxide precursors include tantalum (V) methoxide (structural formula: Ta (OCH 3 ) 5 , molecular weight: 336.12), Kojundo Chemical Laboratory, Ta-10-P Can be mentioned.
  • organic niobium oxide precursors examples include niobium (V) ethoxide (structural formula: Nb (OC 2 H 5 ) 5 , molecular weight: 318.21), High Purity Chemical Laboratory, Nb-05. Can be mentioned.
  • a passivation film By forming a coating type material containing an organic vanadium group oxide precursor and an organic aluminum oxide precursor using a coating method or a printing method, and then removing the organic components by a heat treatment, A passivation film can be obtained. Therefore, as a result, a passivation film containing an organic component may be used.
  • the content of the organic component in the passivation film is more preferably less than 10% by mass, still more preferably 5% by mass or less, and particularly preferably 1% by mass or less.
  • the solar cell element (photoelectric conversion device) of the present embodiment includes the passivation film (insulating film, protective insulating film) described in the above embodiment in the vicinity of the photoelectric conversion interface of the silicon substrate, that is, aluminum oxide and vanadium oxide. And at least one oxide of a vanadium group element selected from the group consisting of tantalum oxide. By containing aluminum oxide and an oxide of at least one vanadium group element selected from the group consisting of vanadium oxide and tantalum oxide, the carrier lifetime of the silicon substrate can be extended and negative fixed charges can be obtained. And the characteristics (photoelectric conversion efficiency) of the solar cell element can be improved.
  • Passivation of passivation material (a2-1) on one side of a 725 ⁇ m thick 8-inch p-type silicon substrate (8 ⁇ ⁇ cm to 12 ⁇ ⁇ cm) with natural oxide film removed beforehand with hydrofluoric acid at a concentration of 0.49% by mass It was applied and placed on a hot plate and prebaked at 120 ° C. for 3 minutes. Thereafter, a heat treatment (firing) was performed at 700 ° C. for 30 minutes in a nitrogen atmosphere to obtain a passivation film containing vanadium oxide and vanadium oxide [vanadium oxide / aluminum oxide 63/37 (mass%)]. It was 51 nm when the film thickness was measured with the ellipsometer. When the FT-IR of the passivation film was measured, a very few peaks due to alkyl groups were observed in the vicinity of 1200 cm ⁇ 1 .
  • the passivation material (a2-1) was applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and subjected to heat treatment (baking) at 650 ° C. for 1 hour in a nitrogen atmosphere.
  • a sample in which both surfaces of the substrate were covered with a passivation film was produced.
  • the carrier lifetime of this sample was measured with a lifetime measuring device (Kobelco Research Institute, Inc., RTA-540). As a result, the carrier lifetime was 400 ⁇ s.
  • the same 8-inch p-type silicon substrate was measured by passivation using the iodine passivation method, and the carrier lifetime was 1100 ⁇ s.
  • the carrier lifetime was 380 ⁇ s.
  • the decrease in carrier lifetime (from 400 ⁇ s to 380 ⁇ s) was within ⁇ 10%, and the decrease in carrier lifetime was small.
  • the passivation film obtained by heat-treating (sintering) the passivation material (a2-1) showed a certain degree of passivation performance and a negative fixed charge.
  • Reference Example 2-2 Similar to Reference Example 2-1, a commercially available organometallic thin film coated material from which aluminum oxide (Al 2 O 3 ) can be obtained by heat treatment (calcination) [High Purity Chemical Laboratory, SYM-AL04, concentration 2 3 mass%] and a commercially available organometallic thin film coating type material [Vitamin Purity Laboratory, V-02, concentration 2 mass%] from which vanadium oxide (V 2 O 5 ) can be obtained by heat treatment, Passivation materials (a2-2) to (a2-7) shown in Table 8 were prepared by mixing at different ratios.
  • each of the passivation materials (a2-2) to (a2-7) was applied to one side of a p-type silicon substrate and heat-treated (fired) to produce a passivation film.
  • the voltage dependence of the capacitance of the obtained passivation film was measured, and the fixed charge density was calculated therefrom.
  • the carrier lifetime was measured using a sample obtained by applying a passivation material to both sides of a p-type silicon substrate and performing heat treatment (firing).
  • the passivation materials (a2-2) to (a2-7) are all negative after the heat treatment (firing). Since it showed a fixed charge and a certain carrier lifetime, it was suggested that it functions as a passivation film. It was found that all the passivation films obtained from the passivation materials (a2-2) to (a2-7) stably show negative fixed charges and can be suitably used as a passivation for a p-type silicon substrate. .
  • the passivation material (b2-1) was applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and subjected to heat treatment (baking) at 600 ° C. for 1 hour in a nitrogen atmosphere.
  • a sample in which both surfaces of the substrate were covered with a passivation film was produced.
  • the carrier lifetime of this sample was measured by a lifetime measuring device (Kobelco Research Institute, Inc., RTA-540). As a result, the carrier lifetime was 400 ⁇ s.
  • the same 8-inch p-type silicon substrate was measured by passivation using the iodine passivation method, and the carrier lifetime was 1100 ⁇ s.
  • the passivation film obtained by heat-treating (firing) the passivation material (b2-1) exhibits a certain degree of passivation performance and a negative fixed charge.
  • the passivation material (b2-2) was applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and subjected to heat treatment (baking) at 600 ° C. for 1 hour in a nitrogen atmosphere. A sample in which both surfaces of the substrate were covered with a passivation film was produced. The carrier lifetime of this sample was measured by a lifetime measuring device (Kobelco Research Institute, Inc., RTA-540). As a result, the carrier lifetime was 170 ⁇ s. For comparison, the same 8-inch p-type silicon substrate was measured by passivation using the iodine passivation method, and the carrier lifetime was 1100 ⁇ s.
  • the passivation film obtained by curing the passivation material (b2-2) exhibited a certain degree of passivation performance and a negative fixed charge.
  • Each of the passivation materials (c2-1) to (c2-6) is a 725 ⁇ m-thick 8-inch p-type silicon substrate (8 ⁇ ⁇ cm to 12 ⁇ ) from which a natural oxide film has been removed in advance with hydrofluoric acid having a concentration of 0.49% by mass.
  • (Cm) was spin-coated on one side, placed on a hot plate, and pre-baked at 120 ° C. for 3 minutes. Thereafter, a heat treatment (firing) was performed at 700 ° C. for 30 minutes in a nitrogen atmosphere to obtain a passivation film containing aluminum oxide and tantalum oxide. Using this passivation film, the voltage dependence of the capacitance was measured, and the fixed charge density was calculated therefrom.
  • each of the passivation materials (c2-1) to (c2-6) is applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and heat-treated (fired) at 650 ° C. for 1 hour in a nitrogen atmosphere. )
  • the carrier lifetime of this sample was measured by a lifetime measuring device (Kobelco Research Institute, Inc., RTA-540).
  • the passivation materials (c2-1) to (c2-6) are all negative after heat treatment (firing). Since it showed a fixed charge and a certain carrier lifetime, it was suggested that it functions as a passivation film.
  • Al oxide (Al 2 O 3 ) As a compound from which aluminum oxide (Al 2 O 3 ) can be obtained by heat treatment (firing), commercially available aluminum triisopropoxide (structural formula: Al (OCH (CH 3 ) 2 ) 3 , molecular weight: 204.25 2.04 g (0.010 mol) was dissolved in cyclohexane 60 g to prepare a passivation material (d2-1) having a concentration of 5% by mass.
  • Al (OCH (CH 3 ) 2 ) 3 As a compound from which aluminum oxide (Al 2 O 3 ) can be obtained by heat treatment (firing), commercially available aluminum triisopropoxide (structural formula: Al (OCH (CH 3 ) 2 ) 3 , molecular weight: 204.25 2.04 g (0.010 mol) was dissolved in cyclohexane 60 g to prepare a passivation material (d2-1) having a concentration of 5% by mass.
  • the passivation material (d2-1) was applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and subjected to a heat treatment (firing) at 600 ° C. for 1 hour in a nitrogen atmosphere.
  • a sample in which both surfaces of the substrate were covered with a passivation film was produced.
  • the carrier lifetime of this sample was measured by a lifetime measuring device (Kobelco Research Institute, Inc., RTA-540). As a result, the carrier lifetime was 610 ⁇ s.
  • the same 8-inch p-type silicon substrate was measured by passivation using the iodine passivation method, and the carrier lifetime was 1100 ⁇ s.
  • the passivation film obtained by heat-treating the passivation material (d2-1) exhibited a certain degree of passivation performance and a negative fixed charge.
  • the passivation material (d2-2) was applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and subjected to heat treatment (baking) at 600 ° C. for 1 hour in a nitrogen atmosphere. A sample in which both surfaces of the substrate were covered with a passivation film was produced. The carrier lifetime of this sample was measured by a lifetime measuring device (Kobelco Research Institute, Inc., RTA-540). As a result, the carrier lifetime was 250 ⁇ s. For comparison, the same 8-inch p-type silicon substrate was measured by passivation using the iodine passivation method, and the carrier lifetime was 1100 ⁇ s.
  • the passivation film obtained by heat treatment (firing) the passivation material (d2-2) exhibits a certain degree of passivation performance and a negative fixed charge.
  • organometallic thin film coating type material High purity chemical research laboratory SYM-AL04, concentration 2.3 mass%
  • aluminum oxide (Al 2 O 3 ) can be obtained by heat treatment (firing)
  • heat treatment (firing) Niobium oxide (Nb 2 O) by commercially available organometallic thin film coating type material (VCO, Ltd., high purity chemical research laboratory V-02, concentration 2 mass%) from which vanadium oxide (V 2 O 5 ) is obtained, and heat treatment (firing) 5 )
  • a commercially available organometallic thin film coating type material [Co-development High Purity Chemical Laboratory, Nb-05, concentration 5 mass%] obtained is mixed to obtain a passivation material (e2-2) which is a coating type material. Prepared (see Table 10).
  • organometallic thin film coating type material High purity chemical research laboratory SYM-AL04, concentration 2.3 mass%] from which aluminum oxide (Al 2 O 3 ) can be obtained by heat treatment (firing), heat treatment (firing) Niobium oxide (Nb) by commercially available organometallic thin film coating material [Tapurio Chemical Lab. Ta-10-P, concentration 10% by mass] from which tantalum oxide (Ta 2 O 5 ) can be obtained, and heat treatment (firing) 2 O 5 ), a commercially available organometallic thin film coating material [High Purity Chemical Laboratory Nb-05, concentration 5 mass%] is mixed to form a passivation material (e2-3) which is a coating material Was prepared (see Table 10).
  • organometallic thin film coating type material High purity chemical research laboratory SYM-AL04, concentration 2.3 mass%
  • aluminum oxide Al 2 O 3
  • heat treatment firing
  • Tantalum oxide Ti 2 O 5
  • heat treatment Niobium oxide
  • Nb 2 O 5 Niobium oxide
  • a commercially available organometallic thin film coating type material [High purity chemical research laboratory Nb-05, concentration 5 mass%] was mixed to prepare a passivation material (e2-4) as a coating type material (see Table 10).
  • Each of the passivation materials (e2-1) to (e2-4) was 725 ⁇ m thick and 8 inches thick with the natural oxide film removed beforehand with hydrofluoric acid having a concentration of 0.49% by mass, as in Reference Example 2-1. It was spin-coated on one side of a p-type silicon substrate (8 ⁇ ⁇ cm to 12 ⁇ ⁇ cm), placed on a hot plate and prebaked at 120 ° C. for 3 minutes. Thereafter, a heat treatment (firing) was performed at 650 ° C. for 1 hour in a nitrogen atmosphere to obtain a passivation film containing aluminum oxide and two or more vanadium group element oxides.
  • each of the passivation materials (e2-1) to (e2-4) is applied to both sides of an 8-inch p-type silicon substrate, pre-baked, and heat-treated (fired) at 650 ° C. for 1 hour in a nitrogen atmosphere. )
  • the carrier lifetime of this sample was measured by a lifetime measuring device (Kobelco Research Institute, Inc., RTA-540).
  • each of the passivation materials (f2-1) to (f2-9) was applied to one side of a p-type silicon substrate, and then heat treatment (firing) was performed to form a passivation film. This was used to measure the voltage dependence of the capacitance, and the fixed charge density was calculated therefrom.
  • a SiN film was formed on the light receiving surface side by plasma CVD as the light receiving surface antireflection film 103.
  • the passivation material (a2-1) prepared in Reference Example 2-1 was applied to the region excluding the contact region (opening OA) on the back surface side of the silicon substrate 101 by an inkjet method. Thereafter, heat treatment was performed to form a passivation film 107 having an opening OA.
  • a sample using the passivation material (c2-1) prepared in Reference Example 2-5 was separately prepared as the passivation film 107.
  • a paste mainly composed of silver was screen-printed in the shape of predetermined finger electrodes and bus bar electrodes.
  • a paste mainly composed of aluminum was screen-printed on the entire surface.
  • heat treatment fire-through
  • electrodes first electrode 105 and second electrode 106
  • aluminum is diffused into the opening OA on the back surface to form the BSF layer 104.
  • the fire-through process in which the SiN film is not perforated is described.
  • the opening OA is first formed in the SiN film by etching or the like, and then the silver electrode is formed. You can also
  • the passivation film 107 is not formed in the above manufacturing process, aluminum paste is printed on the entire back surface, and the p + layer 114 corresponding to the BSF layer 104 and the electrode 116 corresponding to the second electrode. was formed on the entire surface to form a solar cell element having the structure of FIG.
  • characteristic evaluation a short circuit current, an open circuit voltage, a fill factor, and conversion efficiency
  • the characteristic evaluation was performed according to JIS-C-8913 (fiscal 2005) and JIS-C-8914 (fiscal 2005). The results are shown in Table 12.
  • the solar cell element having the passivation film 107 has both the short-circuit current and the open voltage increased as compared with the solar electronic element not having the passivation film 107, and the conversion efficiency (photoelectric conversion efficiency) is 0 at the maximum. It was found to improve by 6%.

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Abstract

　L'invention concerne un élément de cellule photovoltaïque qui comporte: un substrat possédant une surface de réception de la lumière et une surface arrière opposée à la surface de réception de la lumière; une première région de diffusion d'impuretés située sur une partie de la surface de réception de la lumière et dans laquelle des impuretés sont diffusées; une seconde région de diffusion d'impuretés située sur la surface de réception de la lumière, dans laquelle la concentration d'impuretés est inférieure à celle de la première région de diffusion d'impuretés; une électrode de surface de réception de la lumière située sur au moins une partie de la première région de diffusion d'impuretés; une électrode de surface arrière située sur la surface arrière; ainsi qu'une couche de passivation contenant au moins un composé choisi dans le groupe: Nb2O5, Ta2O5, V2O5, Y2O3 et HfO2.
PCT/JP2013/069703 2012-07-19 2013-07-19 Élément de cellule photovoltaïque, sa fabrication ainsi que module de cellule voltaïque WO2014014113A1 (fr)

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