WO2022079887A1 - 多層接合型光電変換素子およびその製造方法 - Google Patents

多層接合型光電変換素子およびその製造方法 Download PDF

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WO2022079887A1
WO2022079887A1 PCT/JP2020/039069 JP2020039069W WO2022079887A1 WO 2022079887 A1 WO2022079887 A1 WO 2022079887A1 JP 2020039069 W JP2020039069 W JP 2020039069W WO 2022079887 A1 WO2022079887 A1 WO 2022079887A1
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layer
electrode
photoelectric conversion
photoactive
conversion element
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French (fr)
Japanese (ja)
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武志 五反田
智博 戸張
穣 齊田
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Toshiba Corp
Toshiba Energy Systems and Solutions Corp
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Toshiba Corp
Toshiba Energy Systems and Solutions Corp
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Priority to PCT/JP2020/039069 priority Critical patent/WO2022079887A1/ja
Priority to JP2022527241A priority patent/JP7190080B2/ja
Priority to CN202180070473.7A priority patent/CN116548083A/zh
Priority to DE112021005470.8T priority patent/DE112021005470T5/de
Priority to PCT/JP2021/036896 priority patent/WO2022080196A1/ja
Publication of WO2022079887A1 publication Critical patent/WO2022079887A1/ja
Priority to US18/301,174 priority patent/US20230317377A1/en
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/50—Organic perovskites; Hybrid organic-inorganic perovskites [HOIP], e.g. CH3NH3PbI3
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/0029—Processes of manufacture
    • H01G9/0036—Formation of the solid electrolyte layer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/20—Light-sensitive devices
    • H01G9/2004—Light-sensitive devices characterised by the electrolyte, e.g. comprising an organic electrolyte
    • H01G9/2009—Solid electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/20—Light-sensitive devices
    • H01G9/2068—Panels or arrays of photoelectrochemical cells, e.g. photovoltaic modules based on photoelectrochemical cells
    • H01G9/2072—Panels or arrays of photoelectrochemical cells, e.g. photovoltaic modules based on photoelectrochemical cells comprising two or more photoelectrodes sensible to different parts of the solar spectrum, e.g. tandem cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/20—Light-sensitive devices
    • H01G9/209—Light trapping arrangements
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
    • H10K30/10—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation comprising heterojunctions between organic semiconductors and inorganic semiconductors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
    • H10K30/80—Constructional details
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K39/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic radiation-sensitive element covered by group H10K30/00
    • H10K39/10—Organic photovoltaic [PV] modules; Arrays of single organic PV cells
    • H10K39/15—Organic photovoltaic [PV] modules; Arrays of single organic PV cells comprising both organic PV cells and inorganic PV cells
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
    • H10K71/10—Deposition of organic active material
    • H10K71/12—Deposition of organic active material using liquid deposition, e.g. spin coating
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
    • H10K30/80—Constructional details
    • H10K30/84—Layers having high charge carrier mobility
    • H10K30/85—Layers having high electron mobility, e.g. electron-transporting layers or hole-blocking layers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
    • H10K30/80—Constructional details
    • H10K30/84—Layers having high charge carrier mobility
    • H10K30/86—Layers having high hole mobility, e.g. hole-transporting layers or electron-blocking layers
    • 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
    • Y02E10/549—Organic PV cells

Definitions

  • An embodiment of the present invention relates to a multi-layer junction type photoelectric conversion element having high efficiency, a large area, and high durability, and a method for manufacturing the same.
  • semiconductor devices such as photoelectric conversion elements or light emitting elements have generally been manufactured by a relatively complicated method such as a chemical vapor deposition method (CVD method).
  • CVD method chemical vapor deposition method
  • these semiconductor devices can be produced by a simpler method, for example, a coating method, a printing method, or a physical vapor deposition method (PVD method), they can be easily manufactured at low cost. Is being sought.
  • semiconductor devices such as solar cells, sensors, or light emitting devices, which are made of organic materials or are made of a combination of organic materials and inorganic materials, are being actively researched and developed. These studies aim to find a device with high photoelectric conversion efficiency. Further, as a target of such research, an element using a perovskite semiconductor can be manufactured by a coating method or the like, and high efficiency can be expected, so that it has been attracting attention in recent years.
  • An object of the present embodiment is to provide a semiconductor device capable of generating electricity with high efficiency and having high durability and a method for manufacturing the same.
  • the multilayer junction type photoelectric conversion element is With the first electrode, The first photoactive layer containing the perovskite semiconductor, A first dope layer and a second photoactive layer containing silicon, With the second dope layer, Passivation layer, second electrode, In this order, The interface existing between the first photoactive layer and the adjacent layer on the second photoactive layer side is a substantially smooth surface. Further, a light scattering layer composed of a plurality of silicon alloy layers separated from each other is further provided, which penetrates a part of the passivation layer and electrically joins the second dope layer and the second electrode. It is a thing.
  • the method for manufacturing the multilayer junction type photoelectric conversion element includes the following steps: (A) A step of forming a first dope layer having a substantially smooth surface on one surface of a silicon wafer constituting the first photoactive layer. (B) A step of forming a passivation layer on the back surface of a silicon wafer on which a first dope layer is formed. (C) A step of forming an opening in the formed passivation layer, (D) A step of applying a metal paste on a passivation layer having an opening formed. (E) A step of heating a silicon wafer coated with a metal paste to form an alloy layer, a second dope layer, and a second electrode. (F) A step of forming a first photoactive layer containing perovskite on the first dope layer by a coating method, and (g) forming a first electrode on the first photoactive layer. Process to do.
  • a multilayer junction type photoelectric conversion element having a large amount of light absorption, suppressed carrier recombination, high efficiency, high generated current amount, and high durability, and manufacturing thereof. The method is provided.
  • FIG. 1 The conceptual diagram which shows the structure of the multilayer junction type photoelectric conversion element by one Embodiment of this invention.
  • FIG. 1 The conceptual diagram which shows the structure of the multilayer junction type photoelectric conversion element by the comparative example 1.
  • the photoelectric conversion element means both an element such as a solar cell or a sensor that converts light into electricity and an element that converts electricity into light.
  • the basic structure of these is the same, although there is a difference in whether the active layer functions as a power generation layer or a light emitting layer.
  • the constituent members of the multilayer junction type photoelectric conversion element according to the embodiment will be described by taking a solar cell as an example, but the embodiment can also be applied to other photoelectric conversion elements having a common structure.
  • FIG. 1 is a schematic diagram showing an example of the configuration of a solar cell, which is one aspect of the multilayer junction type photoelectric conversion element according to the embodiment.
  • the first electrode 101 and the second electrode 110 serve as an anode or a cathode, from which electrical energy generated by the element is extracted.
  • the photoelectric conversion element according to the embodiment has a first photoactive layer 103 containing a perovskite semiconductor, a first doped layer 107, and a second containing silicon between the first electrode 101 and the second electrode 110.
  • the photoactive layer 108, the second dope layer 111, and the passivation layer 109 are provided in this order.
  • the passivation layer 109 has a plurality of openings, and the plurality of silicon alloy layers 112 penetrating the plurality of openings electrically bond the second electrode 110 and the second dope layer 111. ing.
  • the first photoactive layer 103 and the second photoactive layer 108 are excited by incident light to generate electrons or holes in the first electrode 101 and the second electrode 110.
  • each photoactive layer is a layer containing a material that produces light when electrons and holes are injected from the first electrode and the second electrode.
  • the first buffer layer 102 is arranged between the first electrode and the first photoactive layer, and the first photoactive layer 103 and the first dope layer 107 are arranged.
  • a second buffer layer 104, an intermediate transparent electrode 105, and an intermediate passivation layer 106 are arranged between the two.
  • the device according to the embodiment preferably includes these layers.
  • the element illustrated in FIG. 1 includes two photoactive layers, the unit including the photoactive layer containing a perovskite semiconductor is a top cell, and the unit including a photoactive layer containing silicon is a bottom cell. It is a tandem solar cell having a structure connected in series by an intermediate transparent electrode.
  • the first electrode 101 is arranged on the light incident surface side.
  • the first electrode 101 is a complex of a first metal electrode 101a and a first transparent electrode 101b. Since the metal electrode and the transparent electrode have different characteristics, either one or a combination thereof may be used depending on the characteristics.
  • the metal electrode can be selected from any conventionally known metal electrode as long as it has conductivity. Specifically, conductive materials such as gold, silver, copper, platinum, aluminum, titanium, iron, and palladium can be used.
  • the first metal electrode can be formed by any method. For example, it can be formed by applying a paste-like composition containing a metal material on a substrate or a film and then heat-treating it. It is also possible to form a metal electrode by physical vapor deposition (PVD) using a mask pattern. Further, a vacuum heating vapor deposition method, an electron beam vapor deposition method, a resistance heating vapor deposition method and the like can be used. According to these methods, the conversion efficiency and durability of the solar cell can be improved because the damage to the underlying layer, for example, the perovskite semiconductor layer is less than that of the sputter film formation. A screen printing method using a metal paste is also preferable. The metal paste may contain a glass frit or an organic solvent. In addition, light induced plating (LIP) can be used. LIP is a method capable of selectively forming an electrode in a portion where silicon is exposed. In this case, Ni, Ag, Cu or the like can be used as the plating metal.
  • the first electrode is generally formed on a laminate of other layers and then on top of it, for example, on the first buffer layer.
  • it can be formed by applying a paste-like composition containing a metal as described above and heating the composition.
  • the temperature is preferably lower than the annealing temperature of the perovskite-containing active layer described later.
  • the temperature of the element is controlled, a surface different from the electrode forming surface is brought into contact with a stage having a cooling mechanism, and the atmosphere is evacuated. It becomes possible to control by setting.
  • this heating step can be performed at the same time as the heating step in the formation of the second electrode, which will be described later. That is, heating in the manufacturing process of the first metal electrode and the second electrode can be performed at the same time.
  • the first metal electrode has a shape in which a plurality of metal wires are arranged substantially in parallel.
  • the thickness of the first metal electrode is preferably 30 to 300 nm, and the width is preferably 10 to 1000 ⁇ m. If the thickness of the metal electrode is thinner than 30 nm, the conductivity tends to decrease and the resistance tends to increase. If the resistance becomes high, it may cause a decrease in photoelectric conversion efficiency. When the thickness of the metal electrode is 100 nm or less, it has light transmittance and is preferable because it can improve the power generation efficiency and the luminous efficiency.
  • the sheet resistance of the metal electrode is preferably as low as possible, preferably 10 ⁇ / ⁇ or less.
  • the metal electrode may have a single-layer structure or a multi-layer structure in which layers composed of different materials are laminated.
  • the first transparent electrode 101b is a transparent or translucent conductive layer.
  • the first electrode 101b may have a structure in which a plurality of materials are laminated. Further, since the transparent electrode transmits light, it can be formed on the entire surface of the laminated body.
  • Examples of the material of such a transparent electrode include a conductive metal oxide film and a translucent metal thin film. Specifically, indium oxide, zinc oxide, tin oxide, and their composites, indium tin oxide (ITO), indium zinc oxide (IZO), fluorine-doped tin oxide (FTO), and indium zinc oxide.
  • -A film made of conductive glass made of oxide or the like, aluminum, gold, platinum, silver, copper or the like is used.
  • metal oxides such as ITO or IZO are preferred.
  • a transparent electrode made of such a metal oxide can be formed by a generally known method. Specifically, it is formed by sputtering.
  • the thickness of the first transparent electrode is preferably 30 to 300 nm when the electrode material is ITO. If the thickness of the electrode is thinner than 30 nm, the conductivity tends to decrease and the resistance tends to increase. If the resistance becomes high, it may cause a decrease in photoelectric conversion efficiency. On the other hand, when the thickness of the electrode is thicker than 300 nm, the flexibility of the ITO film tends to be low. As a result, when the thickness is thick, it may crack when stress is applied.
  • the sheet resistance of the electrode is preferably as low as possible, and preferably 10 ⁇ / ⁇ or less.
  • the electrode may have a single-layer structure or a multi-layer structure in which layers composed of materials having different work functions are laminated.
  • the first photoactive layer (photoelectric conversion layer) 103 formed by the method of the embodiment has a perovskite structure at least in a part thereof.
  • This perovskite structure is one of the crystal structures and refers to the same crystal structure as the perovskite.
  • the perovskite structure consists of ions A, B, and X, which may take a perovskite structure when ion B is smaller than ion A.
  • the chemical composition of this crystal structure can be represented by the following general formula (1). ABX 3 (1)
  • A can utilize a primary ammonium ion.
  • CH 3 NH 3 + (hereinafter sometimes referred to as MA), C 2 H 5 NH 3 + , C 3 H 7 NH 3 + , C 4 H 9 NH 3 + , and HC (NH 2 ) 2 . + (Hereinafter referred to as FA) and the like, and CH 3 NH 3+ is preferable, but the present invention is not limited to this.
  • A is preferably Cs, 1,1,1-trifluoro-ethylammonium iodide (FEAI), but is not limited thereto.
  • FEAI 1,1,1-trifluoro-ethylammonium iodide
  • B is a divalent metal ion, and Pb 2+ or Sn 2+ is preferable, but the present invention is not limited thereto.
  • X is preferably a halogen ion.
  • it is selected from F-, Cl- , Br-, I- , and At- , and Cl- , Br- or I- is preferable , but not limited to this.
  • the materials constituting the ions A, B, or X may be single or mixed.
  • the constituent ions can function without necessarily matching the stoichiometric ratio of ABX 3 .
  • the ion A constituting the perovskite of the first photoactive layer is composed of an atomic weight or a total atomic weight (molecular weight) constituting the ion of 45 or more. More preferably, it contains 133 or less ions. Since ion A under these conditions has low stability by itself, it may be mixed with general MA (molecular weight 32), but when MA is mixed, it approaches the silicon bandgap of 1.1 eV and is divided into wavelengths. As a tandem to improve efficiency, the overall characteristics are reduced. In addition, the refractive index with respect to the light wavelength is also affected, and the effect of the light scattering layer is reduced.
  • the ion A is a combination of a plurality of ions and contains Cs
  • the ratio of the number of Cs to the total number of ions A is more preferably 0.1 to 0.9.
  • This crystal structure has a unit cell of cubic, tetragonal, orthorhombic, etc., with A at each vertex, B at the body center, and X at each face center of the cube centered on this.
  • the octahedron consisting of one B and six Xs contained in the unit cell is easily distorted by the interaction with A and undergoes a phase transition to a symmetric crystal. It is presumed that this phase transition dramatically changes the physical characteristics of the crystal, causing electrons or holes to be released outside the crystal, resulting in power generation.
  • the thickness of the first photoactive layer is preferably 30 nm to 1000 nm, more preferably 60 to 600 nm.
  • the device according to the embodiment can realize higher conversion efficiency than a general device under a low illuminance condition of about 200 lux.
  • the first photoactive layer can be formed by any method. However, it is preferable to form the first photoactive layer by the coating method from the viewpoint of cost. That is, a coating liquid containing a precursor compound having a perovskite structure and an organic solvent capable of dissolving the precursor compound is applied to a substrate, for example, a first dope layer, an intermediate passivation layer, an intermediate transparent electrode, or a second buffer layer. Apply on top to form a coating. At this time, the surface of the base layer with which the first photoactive layer comes into contact is substantially a smooth surface. That is, the interlayer interface existing between the first photoactive layer and the adjacent layer on the second photoactive layer side is a substantially smooth surface. By forming the base layer in such a shape, the thickness of the first photoactive layer can be made uniform, and the formation of a short-circuit structure can be prevented.
  • the solvent used in the coating liquid for example, N, N-dimethylformamide (DMF), ⁇ -butyrolactone, dimethyl sulfoxide (DMSO) and the like are used.
  • the solvent is not restricted as long as it can dissolve the material, and may be mixed.
  • the first photoactive layer can be formed by applying a single coating solution in which all the raw materials forming the perovskite structure are dissolved in one solution. Further, a plurality of raw materials forming a perovskite structure may be individually prepared as a plurality of solutions, or a plurality of coating liquids may be prepared and coated sequentially.
  • a spin coater, a slit coater, a bar coater, a dip coater, or the like can be used for coating.
  • the coating liquid may further contain additives.
  • additives 1,8-diiodooctane (DIO) and N-cyclohexyl-2-pyrrolidone (CHP) are preferable.
  • the element structure includes a mesoporous structure
  • the leakage current between the electrodes can be suppressed even if pinholes, cracks, voids, etc. occur in the photoactive layer.
  • the element structure does not have a mesoporous structure, it is difficult to obtain such an effect.
  • the coating liquid contains a plurality of raw materials having a perovskite structure
  • the volume shrinkage at the time of forming the active layer is small, so that a film having less pinholes, cracks and voids can be easily obtained.
  • MAI methylammonium iodide
  • a metal halide compound and the like coexist during the formation of the perovskite structure, the reaction with the unreacted metal halide compound proceeds, and a film having few pinholes, cracks and voids can be easily obtained. Therefore, it is preferable to add MAI or the like to the coating liquid or to apply a solution containing MAI or the like on the coating film after coating.
  • the coating liquid containing the precursor of the perovskite structure may be applied twice or more.
  • the active layer formed by the first coating tends to be a lattice mismatch layer, so it is preferable to coat the active layer so as to have a relatively thin thickness.
  • the conditions for the second and subsequent applications are that the rotation speed of the spin coater is relatively fast, the slit width of the slit coater or bar coater is relatively narrow, and the pulling speed of the dip coater is relatively fast. It is preferable that the conditions are such that the solute concentration in the coating solution is relatively thin and the film thickness is thinned.
  • the perovskite structure formation reaction After the perovskite structure formation reaction is completed, it is preferable to perform annealing to dry the solvent. Since this annealing is performed to remove the solvent contained in the perovskite layer, it is preferable to perform this annealing before forming the next layer, for example, a buffer layer on the first photoactive layer.
  • the annealing temperature is 50 ° C. or higher, more preferably 90 ° C. or higher, and the upper limit is 200 ° C. or lower, more preferably 150 ° C. or lower. It should be noted that if the annealing temperature is low, the solvent may not be sufficiently removed, and if the annealing temperature is too high, the smoothness of the surface of the first photoactive layer may be lost.
  • the surface other than the coated surface for example, the surface of the second electrode may be contaminated. Since perovskite contains a corrosive halogen element, it is preferable to remove the contamination.
  • the method for removing the contamination is not particularly limited, but a method of colliding ions with the passivation layer, laser treatment, etching paste treatment, and solvent cleaning are preferable. It is preferable that the contamination is removed before the first electrode is formed.
  • the first buffer layer 102 and the second buffer layer 104 are between the first electrode and the first photoactive layer, or between the first photoactive layer and the tunnel insulating film, respectively. It is a layer that exists. It is a layer that preferentially extracts electrons or holes.
  • the second buffer layer becomes a base layer of the first photoactive layer when present, it is preferable that the surface thereof is substantially smooth.
  • the first buffer layer and the second buffer layer may have a laminated structure of two or more layers.
  • the first buffer layer can be a layer containing an organic semiconductor and a layer containing a metal oxide.
  • the layer containing the metal oxide can play a function of protecting the active layer when forming the first transparent electrode.
  • the first transparent electrode has an effect of suppressing deterioration of the first electrode. In order to fully exert such an effect, the first transparent electrode is preferably a denser layer than the first buffer layer.
  • one of the first buffer layer and the second buffer layer functions as a hole transport layer, and the other functions as an electron transport layer. It is preferable that the semiconductor device is provided with these layers in order to achieve better conversion efficiency, but it is not always essential in the embodiment, and even if one or both of them are not provided. good.
  • the electron transport layer has a function of efficiently transporting electrons.
  • the buffer layer functions as an electron transport layer, it preferably contains either a halogen compound or a metal oxide.
  • Suitable examples of the halogen compound include LiF, LiCl, LiBr, LiI, NaF, NaCl, NaCl, NaI, KF, KCl, KBr, KI, or CsF. Of these, LiF is particularly preferable.
  • the elements constituting the metal oxide are titanium, molybdenum, vanadium, zinc, nickel, lithium, potassium, cesium, aluminum, niobium, tin and barium.
  • Composite oxides containing a plurality of metal elements are also preferred.
  • aluminum-doped zinc oxide (AZO), niobium-doped titanium oxide, and the like are preferable.
  • Titanium oxide is more preferable among these metal oxides.
  • As the titanium oxide amorphous titanium oxide obtained by hydrolyzing titanium alkoxide by the sol-gel method is preferable.
  • an inorganic material such as metallic calcium can be used for the electron transport layer.
  • an n-type semiconductor can also be used for the electron transport layer.
  • the n-type organic semiconductor is preferably fullerene and its derivatives, but is not particularly limited. Specific examples thereof include derivatives having C60, C70, C76, C78, C84 and the like as a basic skeleton.
  • the carbon atom in the fullerene skeleton may be modified with an arbitrary functional group, and the functional groups may be bonded to each other to form a ring.
  • Fullerene derivatives include fullerene-bound polymers. A fullerene derivative having a functional group having a high affinity for the solvent and having a high solubility in the solvent is preferable.
  • Examples of the functional group in the fullerene derivative include a hydrogen atom; a hydroxyl group; a halogen atom such as a fluorine atom and a chlorine atom; an alkyl group such as a methyl group and an ethyl group; an alkenyl group such as a vinyl group; a cyano group; a methoxy group and an ethoxy group.
  • a hydrogen atom such as C60H36 and C70H36, oxide fullerenes such as C60 and C70, and fullerene metal complexes.
  • PCBM [6,6] -phenylC61 butyrate methyl ester
  • PCBM [6,6] -phenylC71 butyrate methyl ester
  • n-type organic semiconductor a small molecule compound that can be formed by vapor deposition can be used.
  • the small molecule compound referred to here is one in which the number average molecular weight Mn and the weight average molecular weight Mw match. Either is 10,000 or less.
  • BCP 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline
  • TpPyPB (1,3,5-tri (p-pyridine-) 3-Il-phenyl) benzene
  • DPPS diphenyl-bis (4-pyridin-3-yl) phenyl) silane
  • the thickness of the electron transport layer is preferably 20 nm or less. This is because the film resistance of the electron transport layer can be lowered and the conversion efficiency can be increased. On the other hand, the thickness of the electron transport layer can be 5 nm or more. By providing an electron transport layer and making it thicker than a certain thickness, the hole blocking effect can be sufficiently exerted, and the generated excitons are prevented from being deactivated before emitting electrons and holes. be able to. As a result, the current can be efficiently taken out.
  • the hole transport layer has a function of efficiently transporting holes.
  • the layer can include a p-type organic semiconductor material or an n-type organic semiconductor material.
  • the p-type organic semiconductor material and the n-type organic semiconductor material referred to here are materials that can function as an electron donor material and an electron acceptor material when a heterojunction or a bulk heterojunction is formed.
  • a p-type organic semiconductor can be used as the material of the hole transport layer.
  • the p-type organic semiconductor preferably contains, for example, a copolymer composed of a donor unit and an acceptor unit.
  • a donor unit fluorene, thiophene, or the like can be used.
  • acceptor unit benzothiadiazole or the like can be used.
  • polythiophene and its derivatives polypyrrole and its derivatives, pyrazoline derivatives, arylamine derivatives, stilben derivatives, triphenyldiamine derivatives, oligothiophene and its derivatives, polyvinylcarbazole and its derivatives, polysilane and its derivatives, side chains or Polysiloxane derivatives with aromatic amines in the main chain, polyaniline and its derivatives, phthalocyanine derivatives, porphyrin and its derivatives, polyphenylene vinylene and its derivatives, polythienylene vinylene and its derivatives, benzodithiophene derivatives, thieno [3,2- b] A thiophene derivative or the like can be used.
  • These materials may be used in combination for the hole transport layer, or a copolymer composed of comonomers constituting these materials may be used.
  • a copolymer composed of comonomers constituting these materials may be used.
  • polythiophene and its derivatives are preferable because they have excellent stereoregularity and have relatively high solubility in a solvent.
  • poly [N-9'-heptadecanyl-2,7-carbazole-alto-5,5- (4', 7), which is a copolymer containing carbazole, benzothiadiazole and thiophene, is used as a material for the hole transport layer.
  • Derivatives such as'-di-2-thienyl-2', 1', 3'-benzothiadiazole)] (hereinafter, may be referred to as PCDTBT) may be used.
  • poly [[4,8-bis [(2-ethylhexyl) oxy] benzo [1,2-b: 4,5-b'] dithiophene-2,6-diyl] [3-fluoro-2-[(2). -Ethylhexyl) carbonyl] thorium [3,4-b] thiopheneyl]] (hereinafter sometimes referred to as PTB7), PTB7-Th (PCE10, or PBDTTT) in which a thienyl group having a weaker electron donating property than the alkoxy group of PTB7 is introduced. -Sometimes called EFT) and the like are also preferable.
  • a metal oxide can be used as the material of the hole transport layer.
  • metal oxide examples include titanium oxide, molybdenum oxide, vanadium oxide, zinc oxide, nickel oxide, lithium oxide, calcium oxide, cesium oxide and aluminum oxide. These materials have the advantage of being inexpensive. Further, thiocyanate such as copper thiocyanate may be used as the material of the hole transport layer.
  • dopants can be used for transport materials such as spiro-OMeTAD and the p-type organic semiconductor.
  • Dopants include oxygen, 4-tert-butylpyrididine, lithium-bis (trifluoromethanesulfonyl) imide (Li-TFSI), acetonitrile, tris [2- (1H-pyrazole-1-yl) pyridine] cobalt (III) tris. (Hexafluorophosphate) salt (commercially available under the trade name "FK102”), Tris [2- (1H-pyrazole-1-yl) pyrimidine] Cobalt (III) Tris [bis (trisfluoromethylsulfonyl) imide] (MY11) Etc. can be used.
  • a conductive polymer compound such as polyethylene dioxythiophene can be used as the hole transport layer.
  • a conductive polymer compound those listed in the section of electrodes can be used.
  • a polythiophene-based polymer such as PEDOT
  • another material such as PEDOT
  • the first buffer layer is preferably an electron transport layer. Further, it is preferably an oxide layer of a metal selected from the group consisting of zinc, titanium, aluminum, tin and tungsten. This oxide layer may be a composite oxide layer containing two or more kinds of metals. This is because the light soaking effect improves the electrical conductivity, so that the electric power generated in the active layer can be efficiently extracted. By arranging this layer on the first electrode side of the active layer, light soaking becomes possible especially with UV light.
  • the first buffer layer preferably has a structure in which a plurality of layers are laminated. In such a case, it is preferable to contain the oxide of the above metal. With such a structure, when a new type of metal oxide is newly formed by sputtering, the active layer and the metal oxide adjacent to the active layer are less likely to be damaged by sputtering.
  • the first buffer layer has a structure including voids. More specifically, a buffer layer composed of a deposit of nanoparticles and having voids between the nanoparticles, a structure composed of a conjugate of nanoparticles and having voids between the bound nanoparticles, and the like. Is preferable.
  • the first buffer layer contains a metal oxide film
  • the film functions as a barrier layer.
  • the barrier layer is provided between the second electrode and the second buffer layer in order to suppress corrosion of the second electrode by a substance penetrating from another layer.
  • the material constituting the perovskite layer tends to have a high vapor pressure at high temperatures.
  • halogen gas, hydrogen halide gas, and methylammonium gas are likely to be generated in the perovskite layer.
  • the device When these gases are confined by the barrier layer, the device may be damaged from the inside due to the increase in internal pressure. In such a case, peeling of the layer interface is particularly likely to occur. Therefore, when the second buffer layer contains voids, the increase in internal pressure is alleviated, and it becomes possible to provide high durability.
  • the first electrode that is, the metal layer is structurally isolated from the first photoactive layer by the metal oxide film
  • the first electrode is less likely to be corroded by substances penetrating from the other layers.
  • the first photoactive layer comprises a perovskite semiconductor. It is generally known that halogen ions such as iodine and bromine diffuse into the device from the photoactive layer containing the perovskite semiconductor, and the component reaching the metal electrode causes corrosion. In the presence of the metal oxide film, it is considered that the diffusion of such a substance can be efficiently blocked. It preferably contains indium tin oxide (ITO), fluorine-doped tin oxide (FTO), and aluminum-doped zinc oxide (AZO).
  • ITO indium tin oxide
  • FTO fluorine-doped tin oxide
  • AZO aluminum-doped zinc oxide
  • the thickness is preferably 5 to 100 nm, more preferably 10 to 70 nm.
  • the same metal oxide as that generally used for the transparent electrode can be used, but the one having physical properties different from the general metal oxide layer used for the transparent electrode is used. It is preferable to use it. That is, it is not only characterized by its constituent materials, but also by its crystallinity or oxygen content.
  • the crystallinity or oxygen content of the metal oxide film contained in the first buffer layer is lower than that of the metal oxide layer formed by sputtering, which is generally used as an electrode.
  • the oxygen content is preferably 62.1 to 62.3 atomic%.
  • the metal oxide film functions as a permeation prevention layer for corrosive substances can be confirmed by elemental analysis in the cross-sectional direction after the durability test.
  • a time-of-flight secondary ion mass spectrometry TOF-SIMS
  • the peak of the deteriorated substance is detected by dividing it into two or more so as to sandwich the material indicating the prevention of penetration of the corrosive substance, and the peak area on the first electrode side is the total area of the other peaks. Is smaller than. If the penetration is completely prevented, the peak on the first electrode side cannot be confirmed.
  • the peak on the first electrode side is so small that it cannot be confirmed, but even if most of the peak is shielded, the durability of the device is greatly improved. That is, even if a part of the first electrode is deteriorated, the characteristics such as the overall electric resistance of the first electrode do not change significantly, so that the conversion efficiency of the solar cell does not change significantly. On the other hand, if the permeation is not sufficiently prevented and the corrosive substance reacts with the first electrode, the characteristics such as the electric resistance of the first electrode change significantly, so that the conversion efficiency of the solar cell changes greatly. (Decrease in conversion efficiency).
  • the peak area on the first electrode side is 0.007 with respect to the total area of the other peaks.
  • the method for forming such a metal oxide film is not particularly limited, but it can be formed by sputtering under specific conditions.
  • the intermediate transparent electrode 105 has a function of electrically connecting the top cell and the bottom cell while isolating them, and guiding the light not absorbed by the top cell to the bottom cell. Therefore, the material can be selected from transparent or translucent conductive materials. Such a material can be selected from the same materials as the first transparent electrode.
  • the thickness of the intermediate bright electrode is preferably 5 nm to 70 nm. If it is thinner than 5 nm, there are many membrane defects, and the separation of the layer adjacent to the intermediate transparent electrode becomes insufficient. If it is thicker than 70 nm, the light transmittance may cause a decrease in the amount of power generation of the bottom cell, for example, a silicon cell due to the diffraction effect.
  • the second transparent electrode 105 may be directly connected to the first dope layer 107, or may be indirectly connected to the second passivation layer 106, if necessary.
  • Such an intermediate passivation film preferably contains a silicon oxide.
  • the passivation layer containing silicon oxide has the effect of reducing carrier loss.
  • the layer may be a uniform layer without openings or a discontinuous layer having some openings.
  • the thickness and the shape of the opening have a specific structure. For example, by providing an opening to limit the electrical connection surface between the top cell and the bottom cell, carrier loss at the connection interface can be reduced, but in this case, the thickness may be 10 nm to 1000 nm. preferable.
  • the shape of the openings may be, for example, groove-shaped openings arranged at regular or random intervals, or the hole-shaped openings may be uniformly or unevenly distributed.
  • the flow of carriers is restricted by the opening, so that the ratio of the total area occupied by the opening to the total area of the intermediate passivation layer is preferably in a specific range. .. Specifically, the ratio is preferably 50 to 95%.
  • the width of the groove is preferably 10 to 500,000 nm, and the average interval between the grooves is preferably 10 to 5,000,000 nm.
  • the width and spacing of the grooves do not have to be constant, but it is preferable to make them substantially constant because the production becomes easy.
  • the shape of the opening is a groove shape (straight line shape)
  • the grooves are arranged substantially in parallel.
  • the width of the grooves is preferably 10 to 500,000 nm, and the average spacing between the grooves is preferably 10 to 5,000,000 nm.
  • the width and spacing of the grooves do not have to be constant, but it is preferable to make them substantially constant because the production becomes easy.
  • the average spacing of the plurality of metal wires constituting the linearly formed first metal electrode is set to a plurality of openings formed in a groove shape in the intermediate passivation layer. It is preferable that the interval is shorter than the average interval of.
  • the shape of the opening is hole-shaped, the shape is not particularly limited, but is generally circular, but may be irregular.
  • the area of each opening is preferably included in the range of 0.01 to 40,000 ⁇ m 2 .
  • the thickness of the passivation layer is preferably 1 nm to 20 nm.
  • the intermediate passivation film can be formed by the same method as the passivation layer described later.
  • the second photoactive layer 108 contains silicon.
  • the silicon contained in the second photoactive layer can adopt the same structure as the silicon generally used for a photovoltaic cell. Specific examples thereof include crystalline silicon containing crystalline silicon such as single crystal silicon, polysilicon, and heterojunction silicon, and thin film silicon containing amorphous silicon. Further, the silicon may be a thin film cut out from a silicon wafer. As the silicon wafer, an n-type silicon crystal doped with phosphorus or the like and a p-type silicon crystal doped with boron or the like can also be used. The electrons in the p-type silicon crystal have a long diffusion length, which is preferable.
  • the thickness of the second photoactive layer is preferably 100 to 300 ⁇ m.
  • first dope layer 107 and the second dope layer 111 are between the first photoactive layer 103 and the second photoactive layer 108, or between the second photoactive layer 108 and the second. These are layers arranged between the electrodes 110 and the electrodes 110.
  • n-type layer, p-type layer, p + type layer, p ++ type layer and the like are combined according to the purpose such as improvement of carrier collection efficiency according to the characteristics of the second photoactive layer. Can be done.
  • the first dope layer can be combined with a phosphorus-doped silicon film (n layer), and the second dope layer can be combined with a p + layer.
  • p + + layers, p ++ layers, and the like can be formed by introducing a required dopant into, for example, amorphous silicon (a-Si).
  • silicon can be deposited by a PECVD method or the like to form an a—Si layer, and a part of the a—Si layer can be crystallized by an annealing treatment to form a layer having high carrier transportability.
  • the doped amorphous silicon can also be formed by forming a film using silane and diborane, or silane and phosphine as raw materials at a low temperature.
  • the a—Si layer can be doped with phosphorus.
  • the method of doping phosphorus is not particularly limited.
  • phosphorus-containing compounds such as POCl 3 and PH 3 can be used.
  • Phosphorus silicate glass (PSG) is widely used as a diffusion source of phosphorus. More specifically, PSG is deposited on the surface of a silicon substrate by utilizing the reaction between POCl 3 and oxygen, and then heat treatment is performed at 800 to 950 ° C., and phosphorus is doped into the silicon substrate by thermal diffusion. be able to. After the doping treatment, PSG can also be removed with acid.
  • the a—Si layer can be doped with boron.
  • the method of doping Poron is not particularly limited.
  • a compound containing boron such as BBr 3 , B 2 H 6 , and BN can be used.
  • Borosilicate glass (BSG) is widely used as a diffusion source of boron. More specifically, BSG is deposited on the surface of the substrate by utilizing the reaction between BBr 3 and oxygen, and then heat treatment is performed at, for example, 800 to 1000 ° C, preferably 850 to 950 ° C, and the silicon substrate is thermally diffused. Boron can be doped into. After the doping treatment, BSG can be removed with acid.
  • a dopant such as phosphorus or boron
  • a laser Such a method can also be used to form a selective emitter.
  • the first dope layer is substantially a smooth surface. Since the first dope layer has a smooth surface, it is suitable for forming a perovskite layer on the smooth surface by coating to a uniform thickness.
  • the bottom cell corresponds to a silicon solar cell.
  • a general silicon solar cell has a textured structure on the surface, but when such a battery is adopted as a bottom cell, the thickness of the perovskite layer formed on it becomes non-uniform, and a short-circuit structure is formed in the thin portion. And deteriorates the characteristics of the solar cell.
  • the texture structure of the surface is eliminated to make the surface smooth, the light reflection on the surface is reduced, the amount of light taken into the silicon layer having a large refractive index is reduced, and as a result, the amount of current is reduced. It ends up.
  • the refractive index is between the refractive index of the atmosphere and the refractive index of silicon, so that the amount of light taken in can be increased even if there is no texture structure.
  • Etching with an acid or an alkali is generally used for forming the texture structure, but in the manufacturing method for the device according to the embodiment, these steps are not required, and the device can be manufactured at low cost and at the same time, no chemical solution is required. Therefore, the environmental load is small. Further, in order to form the top cell, the work of polishing and flattening the texture on one side becomes unnecessary, and the element can be provided at low cost.
  • the first dope layer tends to absorb light having a longer wavelength because the forbidden band width becomes narrower due to the effect of the doping.
  • carriers with a short life tend to be generated in the first dope layer. Therefore, by adopting a substantially uniform layer of uniform thickness instead of adopting a texture structure for the first dope layer, the carrier generation region is narrowed, and carrier generation, in other words, carrier loss is reduced. It can be suppressed. As a result, it is possible to increase the amount of current generated.
  • the carrier generation region can be further limited, so that the amount of current generated can be further increased.
  • the thickness of the first dope layer is preferably 1 to 1000 nm, more preferably 2 to 4 nm.
  • the second dope layer is arranged between the second photoactive layer and the second electrode.
  • the second dope layer physically separates the second photoactive layer from the second electrode in combination with the passivation layer described later. Then, the second dope layer can be formed at the same time as forming the alloy layer described later (details will be described later).
  • the passivation layer 109 is arranged between the second photoactive layer 108 and the second electrode 110.
  • the passivation layer electrically insulates the second photoactive layer from the second electrode, but has an opening, through which the second photoactive layer, the second dope layer, And an electrical connection is secured between the second electrodes. Therefore, since the area where the carrier can move is limited, the carrier can be efficiently collected.
  • the carrier recombination rate at the interface between the second electrode and the second photoactive layer is as fast as about 107 cm / s, which causes a decrease in conversion efficiency.
  • the passivation layer By arranging the passivation layer in between, it can be suppressed.
  • dangling bonds are generally present on the silicon surface, which may also act as a recombination center. This dangling bond can also be reduced by the passivation layer.
  • the material used to form the passivation film is preferably a material capable of reducing dangling bonds on the silicon surface, and is not particularly limited.
  • AlOx formed by a silicon oxide film formed by thermally oxidizing the surface of a silicon material plasma-enhanced chemical vapor deposition (PECVD), plasma-assisted atomic layer deposition (PEALD), or the like.
  • PECVD plasma-enhanced chemical vapor deposition
  • PEALD plasma-assisted atomic layer deposition
  • Examples include a film such as SiNx.
  • the silicon oxide film is formed by thermal oxidation, either dry oxidation in which oxidation is performed in an oxygen atmosphere or wet oxidation in which participation is performed in a water vapor atmosphere can be used.
  • a wet oxide film is suitable for efficiently obtaining an oxide film having a uniform thickness.
  • a good interface by thermal oxidation treatment it is preferable to adopt a high oxidation temperature of about 1000 ° C.
  • a good interface in the low temperature process it is preferable to adopt plasma CVD using an NH 3 / SiH 4 gas system to form a silicon nitride film (SiNx: H).
  • the deposited membrane thus obtained contains a large amount of hydrogen of about 1 ⁇ 10 21 atoms / cm3 .
  • the refractive index and the hydrogen concentration in the membrane can be controlled by changing the flow rate ratio of NH 3 and SiH 4 gas.
  • the passivation layer is formed over the entire surface of the second electrode, but is partially removed in order to obtain an electrical connection between the second photoactive layer and the second electrode.
  • An opening is formed.
  • the opening can be formed by removing a part of the passivation layer by, for example, a wet treatment.
  • the passivation layer is a silicon nitride film
  • hydrogen contained in the silicon nitride film is diffused into the silicon crystal when the alloy layer described later is formed, and the crystal lattice end is terminated by hydrogen to improve the electrical characteristics.
  • the device according to the embodiment has a passivation layer and a light scattering layer on the second electrode.
  • This structure is common to the generally known backside passivation type solar cell (PERC type solar cell).
  • the material used for the second electrode 110 can be selected from any conventionally known material as long as it has conductivity.
  • As the material of the second electrode gold, silver, copper, platinum, aluminum, titanium, iron, palladium and the like are used, but aluminum or silver is preferable. In particular, aluminum is preferable in terms of light reflectivity and cost.
  • the second electrode covers the entire back surface of the element.
  • the second electrode covers the entire back surface to reflect the light that could not be absorbed by the first photoactive layer and the second photoactive layer, and again the second photoactive layer and the first photoactivity. It can be absorbed by the layer, and as a result, the amount of generated current can be increased.
  • the thickness of the second electrode is preferably 20 to 300 nm.
  • the second electrode is electrically connected to the second photoactive layer via an alloy layer penetrating the opening provided in the passivation membrane.
  • the opening and the alloy layer can be formed, for example, as follows. After forming the passivation layer on the back surface of the second photoactive layer, a part of the passivation layer is removed by using a laser or an etching paste to form an opening. A metal paste is applied to the opening and fired to form an alloy layer. The firing is preferably carried out at a temperature of 600 to 1000 ° C. for several seconds.
  • the metal paste preferably contains silver or aluminum.
  • a paste for Fire light is applied to a portion where the alloy layer is to be formed, and the paste and the passivation layer are fired.
  • the opening is not formed in advance, but the passivation layer is denatured when the alloy layer is formed. Therefore, in the embodiment, the denatured portion of the passivation layer is referred to as an opening for convenience.
  • the metal layer formed by these methods typically has a dome-shaped structure.
  • a screen printing method using a metal paste containing silver or aluminum is preferable.
  • the metal paste may further contain a glass frit or an organic solvent.
  • a p + layer in which aluminum is diffused at a high concentration and a silicon alloy layer in which aluminum and silicon are alloyed are formed.
  • the plurality of silicon alloy layers formed in this way form a light scattering layer.
  • the second dope layer in which aluminum is diffused at a high concentration can form a backside electric field (BSF) and reduce carrier recombination.
  • BSF backside electric field
  • the ratio of the total area occupied by the opening to the relative is within a specific range. Specifically, the ratio of the area is preferably 40 to 80%.
  • the alloy layer is also formed linearly.
  • the width of the grooves or the alloy layer is preferably 10 to 500,000 nm, and the average spacing between the grooves or the alloy layer is preferably 20 to 7,000,000 nm.
  • the widths and spacings of the grooves or alloys do not have to be constant, but arranging them substantially constant, i.e., in parallel, facilitates production and is preferred.
  • the average spacing of the plurality of metal wires constituting the linearly formed first metal electrode is set to a plurality of groove-shaped openings (linearly). It is preferable to make it wider than the average spacing of the formed plurality of silicon alloy layers).
  • the shape of the opening is a hole shape
  • the shape is not particularly limited, but is generally circular, but may be irregular.
  • the area of each opening is preferably included in the range of 0.01 to 40,000 ⁇ m 2 .
  • the radius of curvature of the interface between the alloy layer formed on the back surface side of the device and the second dope layer is not constant. That is, the interface has a different radius of curvature for each position, which is suitable for scattering light.
  • the reflectance of the light scattering layer composed of the alloy layer is preferably 80 to 96% in the visible light region. A light scattering layer having such a reflectance can realize effective light reflection with respect to a second photoactive layer (silicon layer) having a reflectance of 30 to 50%.
  • the silicon layer has a high refractive index of 4.2 to 3.5 in the wavelength region of 500 to 1500 nm, whereas the refractive index of the light scattering layer is small, and effective light reflection can be realized from this viewpoint as well. .. Specifically, the refractive index of the light scattering layer is preferably 1.4 to 1.8.
  • the radius of curvature of the interface between the alloy layer and the second dope layer is preferably in the range of 1 to 100 ⁇ m, and more preferably in the range of 1 to 50 ⁇ m. Further, the distance from the alloy layer (light scattering layer) to the second photoactive layer is preferably 100 to 400 ⁇ m.
  • the radius of curvature at the interface has such a range, it is possible to efficiently absorb light whose optical path has changed in a complicated manner. By adopting such a configuration, it is possible to maximize the amount of current that can be taken out from the element according to the embodiment.
  • the radius of curvature becomes larger as the portion closer to the apex.
  • Such a shape can be realized by increasing the removal range of the passivation layer and reducing the depth at which the alloy is formed when the alloy layer is formed.
  • an antireflection layer may be provided on the outermost layer of the device, that is, the interface with the atmosphere.
  • Such an antireflection film can be used as a generally known material such as SnNx or MgF 2 . These materials can be formed into a film by a PECVD method, a vapor deposition method, or the like.
  • the first electrode and the second electrode need to obtain an electrical connection with the outside in order to draw a current from the device. Therefore, it is preferable to remove a part of the antireflection film so as not to obstruct the electrical connection.
  • a wet etching treatment method, a method using an etching paste, a method using a laser, or the like can be used.
  • the element illustrated in FIG. 1 includes two photoactive layers, the unit including the photoactive layer containing a perovskite semiconductor is a top cell, and the unit including a photoactive layer containing silicon is a bottom cell. It is a tandem solar cell having a structure connected in series by an intermediate transparent electrode. Generally, the bandgap of a silicon solar cell is about 1.1 eV, but by combining it with a photovoltaic cell containing a perovskite semiconductor having a relatively wide bandgap, light in a wider wavelength range can be efficiently emitted. It becomes possible to absorb.
  • the open circuit voltage of a silicon solar cell is 0.6 to 0.75 V
  • the open circuit voltage of a perovskite solar cell is 0.9 to 1.3 V.
  • the tandem solar cell that combines these, by increasing the amount of power generated by the perovskite solar cell, it is possible to obtain electric power having a higher voltage than that of the silicon solar cell alone. That is, the output obtained by the tandem solar cell can exceed that of the silicon solar cell alone. Since the tandem solar cell is a series circuit of the top cell and the bottom cell, the voltage can be obtained to be close to the total of the top cell and the bottom cell.
  • the current is rate-determined by the lower current of the top cell and the bottom cell.
  • the material of the active layer is selected to change the wavelength range of the absorbed light, or the thickness of the photoactive layer is adjusted to change the amount of absorbed light. Is done. Since the short-circuit current density of a silicon solar cell is generally about 40 mA / cm 2 by itself, it is preferable to adjust the short-circuit current density of the top cell and the bottom cell to about 20 mA / cm 2 in a tandem solar cell.
  • the multilayer junction type photoelectric conversion element according to the embodiment can be manufactured by laminating the above-mentioned layers in an appropriate order.
  • the stacking order is not particularly limited as long as a desired structure can be obtained, but for example, it can be produced in the following order.
  • B A step of forming a passivation layer on the back surface of a silicon wafer on which a first dope layer is formed.
  • C A step of forming an opening in the formed passivation layer
  • D A step of applying a metal paste on a passivation layer having an opening formed.
  • (E) A step of heating a silicon wafer coated with a metal paste to form an alloy layer, a second dope layer, and a second electrode.
  • (F) A step of forming a first photoactive layer containing perovskite on the first dope layer by a coating method, and (g) forming a first electrode on the first photoactive layer. Process to do.
  • any of the following steps can be combined between the steps (e) and (f).
  • (E1) A step of forming an intermediate passivation layer having an opening on the surface of the first dope layer, if necessary.
  • (E2) A step of forming an intermediate transparent electrode on the first dope layer or the intermediate passivation layer, if necessary.
  • (E3) A step of forming a second buffer layer on the first dope layer, the intermediate passivation layer, or the intermediate transparent electrode, if necessary.
  • step (F1) A step of forming a first buffer layer on the first photoactive layer, Can also be combined.
  • the bottom cell containing the second photoactive layer is formed first, and the top cell containing the first photoactive layer is formed later.
  • the step (e) of heating at a high temperature is performed before the step (f)
  • the first photoactive layer is less likely to be damaged by heat.
  • the first electrode is formed by the step (g)
  • the first photoactive layer is heated, but when it is heated in the step (g), it is heated in the step (f). It is preferable to adopt a temperature lower than the temperature.
  • Example 1 A multilayer junction type photoelectric conversion element having the structure shown in FIG. 1 is manufactured.
  • Phosphorus can be doped on the surface of the p-type silicon wafer constituting the second photoactive layer as the first doping layer to form an n-layer.
  • Phosphorus can be doped into silicon by depositing PSG on the surface of a silicon wafer using the reaction of POCl 3 and oxygen and then performing a heat treatment at 900 ° C. PSG can be removed by acid treatment. In this way, a substantially smooth first dope layer can be formed.
  • AlOx: H layer and SnNx: H layer can be formed as passivation layers on the surface of the silicon wafer opposite to the n layer by the PECVD method.
  • a portion of the passivation layer can be removed with a 532 nm laser to form an opening.
  • the aluminum paste is applied so as to cover the entire back surface and fired in an oven at 950 ° C., the aluminum that has penetrated into the opening reacts with the silicon wafer to form an alloy layer, and further, the alloy layer is formed.
  • a second dope layer can be formed at the interface between the silicon wafer and the silicon wafer.
  • a silicon oxide film can be formed as an intermediate passivation film on the first dope layer.
  • a part of the silicon oxide film can be removed by a laser to form an opening.
  • ITO can be formed as an intermediate transparent electrode by a sputtering method. At this time, the thickness of the intermediate electrode can be adjusted to 20 nm.
  • a second buffer layer can be formed by spin-coating an alcohol dispersion of NiOx particles on the intermediate transparent electrode. After the film formation, annealing can be performed at 150 ° C.
  • the first photoactive layer is a precursor solution in which the precursor of Cs 0.17 FA 0.83 Pb (Br 0.17 I 0.83 ) 3 is dissolved in a mixed solvent of DMF and DMSO (DMSO is 10 Vol%). It can be formed by coating. After film formation, annealing is performed at 150 ° C. for 5 minutes.
  • the first buffer layer can be formed by forming a C60 film of 50 nm on the first photoactive layer with a vapor deposition machine.
  • SnOx can be formed into a 10 nm film by ALD to form the first buffer layer as a composite film.
  • IZO can be formed into a film by spatter as the first transparent electrode.
  • silver can be deposited with a vapor deposition machine as the first metal electrode.
  • the amount of light absorption can be increased by forming the top cell containing the photoactive layer containing perovskite on the bottom cell having the silicon layer, and as a result, the photoelectric flow rate can be increased. To increase. Further, by forming the scattering layer, the light that could not be absorbed by the first and second photoactive layers and silicon can be scattered and reflected and reused for the photocurrent.
  • the passivation layer is arranged between the second electrode and the second photoactive layer, the effect of preventing carrier recombination at the electrode interface can be obtained.
  • the amount of current can be increased by the light scattering effect and the carrier recombination prevention effect.
  • Comparative Example 1 An element having the structure shown in FIG. 2 is formed.
  • the element shown in FIG. 2 can be formed by the same method as in the first embodiment except that the passivation layer is not provided with an opening. Since no opening is provided, an alloy layer (light scattering layer) is not formed.
  • the element according to Comparative Example 1 has a smooth first dope layer, but has a top cell containing a perovskite semiconductor, so that the light absorption to the second photoactive layer is relatively large.
  • the light that could not be absorbed by each photoactive layer is specularly reflected by the second electrode, but is not scattered.
  • the distribution of the amount of light incident on the first and second photoactive layers becomes non-uniform.
  • the generated carrier concentration also becomes non-uniform, and where the amount of light is high, the carrier concentration becomes high, the carrier recombination loss increases, and the amount of current decreases.
  • the passivation layer does not exist, carrier recombination occurs in the vicinity of the second dope layer, and the amount of current is reduced.
  • Multilayer junction type photoelectric conversion element 101 ... First electrode 101a ... First metal electrode 101b ... First transparent electrode 102 ... First buffer layer 103 ... First One photoactive layer 104 ... Second buffer layer ... 105 ... Intermediate transparent electrode 106 ... Intermediate passivation layer 107 ... First dope layer 108 ... Second photoactive layer 109 ... Passivation layer 110 ... Second electrode 111 ... -Second dope layer 112 ... Silicon alloy layer (light scattering layer) 101 ... Multilayer junction type photoelectric conversion element (comparative example) 111a ... Second dope layer

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