JP6670430B2 - Photovoltaic element and method of manufacturing photovoltaic element - Google Patents

Description

  The present invention relates to a photovoltaic element.

  Various types of devices and devices have been devised as photovoltaic devices that convert light energy into electric energy, including so-called solar cells. These photovoltaic elements are roughly classified into those using a silicon-based material and those using a compound-based material as a substance having a photovoltaic effect.

  Typical examples using silicon-based materials include those using single crystal silicon, polycrystalline silicon, heterojunction type, amorphous silicon, and thin film polycrystalline silicon. On the other hand, as a compound using a compound material, a group III-V compound, CIS (using copper (Cu), indium (In), selenium (Se) as a main component), CIGS (main component) (Cu), indium (In), gallium (Ga), selenium (Se), CdTe, organic thin film, dye-sensitized type, and the like.

  FIG. 3 shows a conventional example of the present invention. Of the substrate 1 and the substrate 2, at least the substrate 1 on the light incident side is made of a transparent material, and preferably both are made of a transparent material. On the substrate 1 and the substrate 2, a transparent conductive film 3 is formed. The conductive film 3 is preferably FTO (fluorine-doped tin oxide).

A first photovoltaic layer 6 is formed on the conductive film 3 of the substrate 1. As the first photovoltaic layer 6, an oxide semiconductor layer is representative, and specifically, TiO ₂ , SnO, ZnO, WO ₃ , Nb ₂ O ₅ , In ₂ O ₃ , ZrO ₂ , Ta ₂ Oxide semiconductors such as O ₅ and TiSrO ₃ are preferable. More preferably, a porous titanium dioxide layer solidified by sintering.
In addition, these first photovoltaic layers 6 carry a sensitizing dye.

On the upper surface of the conductive film 3 of the substrate 2, platinum (Pt) film is formed as the charge exchange layer 4.
The electrolyte 8 is sealed between the charge exchange layer 4 of the substrate 2 and the first photovoltaic layer 6 of the substrate 1 while being surrounded on all sides by a sealing material 7.

In the dye-sensitized photovoltaic device having the above-described configuration, the maximum output has been about 48 μW / cm ² under an illumination of about 1000 lux according to the announcement by ROHM.

  Therefore, the present invention provides a photovoltaic element that performs photovoltaic power generation more efficiently by using a material that can be obtained at low cost.

  One of the typical photovoltaic elements for solving the above-mentioned problem uses a colloidal silica layer on the upper surface of the charge exchange layer 4 on the positive electrode side.

  Another typical photovoltaic element is one in which the positive electrode-side charge exchange layer 4 contains colloidal silica.

ADVANTAGE OF THE INVENTION According to this invention, the power generation output per unit area can be improved significantly at low manufacturing cost compared with the conventional photovoltaic element.
Problems, configurations, and effects other than those described above will be clarified by the following embodiments.

FIG. 1 is a cross-sectional view of a photovoltaic device according to a first embodiment in which a colloidal silica layer is supported on an upper surface of a charge exchange layer. FIG. 2 is a cross-sectional view of a photovoltaic device in Example 2 in which colloidal silica is contained in a charge exchange layer. FIG. 3 is a cross-sectional view of a conventional dye-sensitized solar cell.

(Common items of Example 1 and Example 2)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, items common to the first and second embodiments will be described.
FIG. 1 is a cross-sectional view of the photovoltaic device in Example 1 in which a colloidal silica layer 5 is supported on the upper surface of the charge exchange layer 4 on the positive electrode side. FIG. 2 is a cross-sectional view of the photovoltaic device in Example 2 in which the charge exchange layer on the positive electrode side contains colloidal silica.
The following points are common to FIGS. 1 and 2 and will be described with reference to FIG.

In FIG. 1, at least the substrate 1 on the light incident side of the substrate 1 and the substrate 2 is made of a transparent material, and preferably both are made of a transparent material. As the transparent material, glass is generally used, but a resin such as plastic may be used in addition to glass. The substrate 2 may be made of a material to which a conductive agent such as a metal plate or graphene is applied, instead of a transparent material.
On the substrate 1 and the substrate 2, a transparent conductive film 3 is formed, and they are arranged so that the conductive films face each other. The conductive film 3 is preferably FTO (fluorine-doped tin oxide), but may be, for example, indium-tin composite oxide (ITO) in addition to the FTO layer.

A first photovoltaic layer 6 is formed on the conductive film 3 formed on the substrate 1. As the first photovoltaic layer 6, an oxide semiconductor layer is representative, and specifically, TiO ₂ , SnO, ZnO, WO ₃ , Nb ₂ O ₅ , In ₂ O ₃ , ZrO ₂ , Ta ₂ Oxide semiconductors such as O ₅ and TiSrO ₃ are preferable. More preferably, a porous titanium dioxide layer solidified by sintering.

_{Further, CdS, ZnS, In 2 S} , PbS, Mo 2 S, WS2, Sb 2 S3, Bi 2 S 3, ZnCdS 2, may be a sulfide semiconductor such as CuS _2. Furthermore, metal chalcogenides such as CdSe, In ₂ Se ₂ , WSe ₂ , PbSe, and CdTe are also applicable.
Further, an elemental semiconductor such as GaAs, Si, Se, and InP may be used.
Further, a composite of two or more of the above substances, such as a composite of SnO and ZnO, a composite of TiO ₂ and Nb ₂ O ₅ , can also be used.
The type of semiconductor is not limited to these, and two or more types can be used in combination.
The thickness of the first photovoltaic layer 6 is preferably 3 to 30 μm in the height direction, and more preferably 6 to 20 μm.

The first photovoltaic layer 6 supports a sensitizing dye. Various dyes can be used as the dye to be carried on the first photovoltaic layer 6 as long as they exhibit a sensitizing action. Ru complexes such as complexes, coumarin dyes, merocyanine dyes, organic dyes such as polyene dyes, metal porphyrin dyes, phthalocyanine dyes, and the like are applicable. Among these, a Ru complex is preferable, and an N719 dye and a black dye are particularly preferable because they have a broad absorption spectrum in a visible light region.
These dyes may be used alone or in combination of two or more.

  A conductive film 3 is formed on the upper surface of the substrate 2. The conductive film on the upper surface of the substrate 2 is preferably FTO (fluorine-doped tin oxide), but may be, for example, indium-tin composite oxide (ITO) instead of the FTO layer.

  A charge exchange layer (4 in FIG. 1 and 9 in FIG. 2) is formed on the upper surface of the conductive film 3 on the upper surface of the substrate 2 on the positive electrode side. As the charge exchange layer, a platinum (Pt) film is preferable, but a carbon electrode, a conductive polymer, or the like can be used instead of the platinum (Pt) film.

  The electrolyte 8 is sealed between the colloidal silica layer 5 or the colloidal silica-containing charge exchange layer 9 and the first photovoltaic layer 6 while being surrounded on all sides by a sealing material 7. The electrolyte 8 is used in a conventional dye-sensitized solar cell, and may be in any of a liquid state, a solid state, a solidified state, and a normal temperature molten salt state.

  Examples of the electrolyte include a combination of metal iodide and iodine such as lithium iodide, sodium iodide, potassium iodide, and cesium iodide; A combination of an iodine salt and an iodine of a quaternary ammonium compound, or a combination of a bromine compound and a bromine instead of the iodine and the iodine compound, a combination of a cobalt complex, and the like may be used.

  When the electrolyte is an ionic liquid, a solvent need not be particularly used. The electrolyte may be a gel electrolyte, a polymer electrolyte, or a solid electrolyte, or an organic charge transport material may be used instead of the electrolyte.

  Examples of the solvent in the case where the electrolyte 8 is in the form of a solution include nitrile solvents such as acetonitrile, methoxyacetonitrile, and propionitrile, carbonate solvents such as ethylene carbonate, and ether solvents.

The electrolyte 8 used in Examples 1 and 2, specifically, 0.05 mol 0.1 mol, the _{I 2} and LiI, 4-tetra - butyl pyridine 0.5 mol, tetrabutylammonium iodide 0 0.5 mol, added to acetonitrile solvent.

The method of evaluating the maximum output value per unit area in this specification is as follows.
Using an LED light (manufactured by Cosmo Techno Co., Ltd.), light was incident from the substrate 1 side, and light having a value of 1000 lux was irradiated to a photovoltaic element to be measured by an illuminometer DT-1309 manufactured by CEM. Using a digital multimeter, the IV characteristics of the photovoltaic element to be measured were measured to obtain the values of the short-circuit current, open-circuit voltage, shape factor ff, and the maximum output value per unit area.

  Hereinafter, features of each embodiment will be described with reference to the drawings. The other parts are the same as in the description of the common items of the first and second embodiments.

(Example 1)
FIG. 1 is a diagram for explaining the first embodiment. In FIG. 1, a colloidal silica layer 5 coated with colloidal silica is formed on the charge exchange layer 4.

Colloidal silica is a colloid of SiO ₂ or a hydrate thereof, and has a particle size of several nm to 300 nm. Colloidal silica is generally marketed for surface treatment, abrasives, food, cosmetics, and the like.

In Example 1, a platinum (Pt) film is formed as the charge exchange layer 4 on the upper surface of a commercially available glass substrate with a transparent conductive film (for example, a TCO glass substrate VU film manufactured by Asahi Glass Co., Ltd.), and And a colloidal silica layer 5 formed by coating colloidal silica. Various colloidal silicas having various shapes and particle sizes are commercially available. Among them, to apply the present invention, the shape has a high sphericity is preferably close to a sphere, Tsubukei is preferable 5 nm to 100 nm, in particular those of 30nm~60nm arbitrariness.
In general, colloidal silica has a high electron quantum effect at 5 nm to 10 nm and a high light quantum effect at 40 nm to 70 nm.
In this example, the particle size was 30 to 50 nm, and the shape used was a shape close to a true sphere. There are several methods for forming the colloidal silica layer 5. In the present embodiment, a uniformly dispersed layer was formed by applying colloidal silica in a dispersed state on the charge exchange layer 4. . According to this method, the silica itself is homogeneously dispersed on the platinum (Pt) film by the mutual molecular force, and a high-quality colloidal silica layer 5 can be obtained. Further, since colloidal silica itself is generally commercially available, it can be easily obtained, and a photovoltaic device can be manufactured by a simple method.
Other requirements are the same as those described in the first and second embodiments.

As a result, as shown in Table 1, compared with the conventional example, the power generation output per unit area could be significantly improved at a lower manufacturing cost.

  In the first embodiment, the colloidal silica layer 5 is disposed on the upper surface of the positive-electrode-side charge exchange layer, as compared with the conventional example, so that diffused reflection of light is induced in the colloidal silica layer 5 and, in addition, quantum effects of light and electrons are caused. It is thought that the photovoltaic power generation efficiency increased significantly, and the photovoltaic power generation efficiency increased.

(Example 2)
FIG. 2 is a diagram for explaining the second embodiment. In FIG. 2, a platinum film containing colloidal silica is used as the charge exchange layer.

The glass substrate with a transparent conductive film and colloidal silica used in Example 2 are the same as those used in Example 1.
Various methods are conceivable for forming the charge exchange layer 9 containing colloidal silica. In this embodiment, a method of mixing colloidal silica with chloroplatinic acid or a platinum paste and sintering the mixture is adopted. That is, the charge exchange layer containing colloidal silica is formed in the charge exchange layer by mixing colloidal silica into the material component of the charge exchange layer and sintering.

As a result, as shown in Table 2, also in Example 2, the power generation output per unit area could be significantly improved at lower manufacturing cost than in the conventional example.

  In the second embodiment, light also enters the platinum (Pt) layer, which is the charge exchange layer on the positive electrode side. For this reason, by containing colloidal silica in the platinum layer, irregular reflection of light by colloidal silica is induced even in the colloidal silica-containing charge exchange layer 9, and in addition, the quantum effect of light and electrons is extremely increased, and the photovoltaic power generation efficiency is improved. It is thought to have risen.

The present invention is not limited to the first and second embodiments, and various modifications are possible. For example, the particle diameter, shape, and film thickness of colloidal silica can be appropriately changed.
Similarly, the amount, density, particle diameter, shape, and the like of the colloidal silica that is disposed on or contained in the positive electrode-side charge exchange layer can be appropriately changed.
Furthermore, the glass substrate with a transparent conductive film used on the positive electrode side is not limited to those used in the examples.
In addition, it goes without saying that it is also possible to add, delete, or substitute other materials and configurations for a part of each embodiment.

1 ... Substrate (light incident side)
2 ... substrate 3 ... conductive film 4 ... charge exchange layer 5 ... colloidal silica layer 6 ... first photovoltaic layer 7 ... sealing material 8 ... electrolyte 9 ...・ Charge exchange layer containing colloidal silica

Claims (3)

A photovoltaic element that forms a charge exchange layer containing colloidal silica in the charge exchange layer by mixing colloidal silica into the material component of the charge exchange layer and sintering when forming the charge exchange layer on the positive electrode side Manufacturing method. The method for manufacturing a photovoltaic device according to claim 1, wherein a material component of the charge exchange layer contains platinum. The method for manufacturing a photovoltaic device according to claim 1, wherein the step of mixing colloidal silica into the material component of the charge exchange layer is a step of mixing colloidal silica with chloroplatinic acid or a platinum paste .

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