JP2018081989A - Photoelectric conversion element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion element having excellent humidity resistance.SOLUTION: A photoelectric conversion element comprises a transparent substrate and at least one photoelectric conversion cell provided on one surface of the transparent substrate. The photoelectric conversion cell comprises an electrode provided on the one surface of the transparent substrate, a counter substrate facing the electrode, an oxide semiconductor layer provided between the electrode and the counter substrate, and an annular sealing part provided between the transparent substrate and the counter substrate. The counter substrate includes a metal substrate. The metal substrate of the photoelectric conversion cell and a connection terminal provided outside the sealing part on one surface side of the transparent substrate are connected by a conductive member. An area ratio (A/W) of an area A (unit: mm) in the interface between the conductive member and the metal substrate to an area W (unit: mm) of a surface on the transparent substrate side in the oxide semiconductor layer is 0.029 or higher.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a photoelectric conversion element.

  As a photoelectric conversion element, a photoelectric conversion element using a dye is attracting attention because it is inexpensive and high photoelectric conversion efficiency is obtained, and various developments have been made on photoelectric conversion elements using a dye.

  A photoelectric conversion element using a dye generally includes a transparent substrate and at least one photoelectric conversion cell provided on one surface of the transparent substrate. The photoelectric conversion cell includes an electrode provided on the transparent substrate, and an electrode. A counter substrate such as an opposing counter electrode, an annular sealing portion provided between the transparent substrate and the counter substrate, an oxide semiconductor layer provided between the electrode and the counter substrate, and an oxide semiconductor layer With pigments.

  As a photoelectric conversion element using such a dye, for example, a dye-sensitized photoelectric conversion element described in Patent Document 1 below is known. The following Patent Document 1 discloses a dye-sensitized photoelectric conversion including a conductive member that connects a metal substrate of at least one photoelectric conversion cell and a transparent conductive layer provided on one surface of the transparent substrate and outside the sealing portion. An element is disclosed.

Japanese Patent No. 5802817

  However, the dye-sensitized photoelectric conversion element described in Patent Document 1 has the following problems.

  That is, the dye-sensitized photoelectric conversion element described in Patent Document 1 has room for improvement in terms of moisture resistance.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a photoelectric conversion element having excellent moisture resistance.

  As a result of studying the dye-sensitized photoelectric conversion element of Patent Document 1 in order to solve the above problems, the present inventors have seen the dye-sensitized photoelectric conversion element of Patent Document 1 from the transparent substrate side. It has been found that the ratio of the area of the interface between the conductive member and the metal substrate to the area of the oxide semiconductor layer, that is, the power generation area, affects the moisture resistance. As a result of further earnest studies, the present inventors have found that the above-described problems can be solved by the following invention.

That is, the present invention is a photoelectric conversion element comprising a transparent substrate and at least one photoelectric conversion cell provided on one surface of the transparent substrate, wherein the photoelectric conversion cell is provided on the one surface of the transparent substrate. An electrode, a counter substrate facing the electrode, an oxide semiconductor layer provided between the electrode and the counter substrate, and an annular sealing portion provided between the transparent substrate and the counter substrate. The counter substrate includes a metal substrate, and the metal substrate of the photoelectric conversion cell and a connection terminal provided on the one surface side of the transparent substrate and outside the sealing portion are connected by a conductive member, The area ratio (A / W) of the area A (unit: mm ² ) of the interface between the conductive member and the metal substrate to the area W (unit: mm ² ) of the surface of the oxide semiconductor layer on the transparent substrate side. ) Is 0.0 It is a photoelectric conversion element which is 29 or more.

  According to this photoelectric conversion element, even when the surrounding humidity increases, the conductive member is difficult to peel from the metal substrate of the counter substrate, and an increase in contact resistance between the conductive member and the metal substrate is sufficiently suppressed. A decrease in current is suppressed. Therefore, the photoelectric conversion element of the present invention can have excellent moisture resistance.

  In the said photoelectric conversion element, it is preferable that the said electrically-conductive member contains resin and the said area ratio (A / W) is 0.620 or less.

  In this case, even if the conductive member expands and contracts in the in-plane direction of the metal substrate as the ambient temperature changes, the conductive member is in the plane of the metal substrate as compared with the case where the area ratio A / W exceeds 0.620. It becomes difficult to expand and contract in the direction. For this reason, in the photoelectric conversion cell, the conductive member is expanded and contracted in the in-plane direction of the metal substrate, so that the counter substrate is sufficiently prevented from separating from the electrode, and the distance between the counter substrate and the electrode is hardly increased. The increase in resistance is sufficiently suppressed. As a result, the photoelectric conversion element can have excellent durability against temperature changes.

  According to the present invention, a photoelectric conversion element having excellent moisture resistance is provided.

It is a top view which shows one Embodiment of the photoelectric conversion element of this invention. It is a cut surface end view along the II-II line of FIG. It is a top view which shows the pattern of the transparent conductive layer in the photoelectric conversion element of FIG. It is a top view which shows the part which removed the protective layer among the photoelectric conversion elements of FIG. It is sectional drawing which shows the state which cut | disconnected the part which removed the protective layer among the photoelectric conversion elements of FIG. 4 with the plane which crosses a sealing part. It is a top view which shows the structure obtained in the middle of the manufacturing method of the photoelectric conversion element of FIG.

  Hereinafter, an embodiment of the photoelectric conversion element of the present invention will be described in detail with reference to FIGS. 1 is a plan view showing an embodiment of the photoelectric conversion element of the present invention, FIG. 2 is a cross-sectional end view taken along the line II-II in FIG. 1, and FIG. 3 is transparent in the photoelectric conversion element in FIG. 4 is a plan view showing a pattern of the conductive layer, FIG. 4 is a plan view showing a part of the photoelectric conversion element of FIG. 1 from which the protective layer is removed, and FIG. 5 is a part of the photoelectric conversion element of FIG. 4 from which the protective layer is removed. It is sectional drawing which shows the state cut | disconnected by the plane which crosses a sealing part.

  As shown in FIGS. 1 and 2, the photoelectric conversion element 100 includes a transparent substrate 11 having a light receiving surface 11a and one surface of the transparent substrate 11 opposite to the light receiving surface 11a (hereinafter referred to as “cell installation surface”). One photoelectric conversion cell 20 provided on 11b and a protective layer 30 provided on the cell installation surface 11b side of the transparent substrate 11 and covering and protecting the photoelectric conversion cell 20 are provided.

  As shown in FIG. 3, the transparent conductive layer 12 is provided on the cell installation surface 11 b of the transparent substrate 11. The transparent conductive layer 12 includes an electrode 12A, a conductive first current extraction unit 12B for extracting current from the photoelectric conversion cell 20, and a conductive second current extraction unit 12D for extracting current from the photoelectric conversion cell 20. And a separation portion 12C provided so as to surround the electrode 12A, the first current extraction portion 12B, and the second current extraction portion 12D. The electrode 12A, the first current extraction unit 12B, and the separation unit 12C are disposed in a state of being insulated from each other via the groove 40. The electrode 12A and the second current extraction unit 12D are connected to each other. The separation portion 12C, the first current extraction portion 12B, and the second current extraction portion 12D are disposed in a state of being insulated from each other via the groove 40. The first current extraction portion 12B and the second current extraction portion 12D are also arranged in a state of being insulated from each other so as to be adjacent to each other through the groove 40.

  As shown in FIG. 2, the photoelectric conversion cell 20 is provided between the transparent substrate 11 and the counter substrate 50, the electrode 12 </ b> A provided on the cell installation surface 11 b of the transparent substrate 11, the counter substrate 50 facing the electrode 12 </ b> A. The annular sealing portion 60, the oxide semiconductor layer 13 provided on the electrode 12A, the insulating layer 70 provided at least between the sealing portion 60 and the electrode 12A, and between the electrode 12A and the counter substrate 50. And an electrolyte 80 to be disposed.

  As shown in FIGS. 2 and 5, a first external connection terminal 15a is provided on the first current extraction portion 12B, and is sealed with the first external connection terminal 15a on the first current extraction portion 12B. The connection terminal 16 is provided between the unit 60 and the first external connection terminal 15a. On the other hand, as shown in FIG. 5, a second external connection terminal 15b is provided on the second current extraction portion 12D. In addition, a current collection wiring 17 having a lower resistance than that of the electrode 12A and the second current extraction part 12D is provided so as to straddle the second current extraction part 12D and the electrode 12A. (Referred to as “first current collector wiring end”) 17a is located on the second current extraction portion 12D and spaced apart from the second external connection terminal 15b between the second external connection terminal 15b and the sealing portion 60. The other end (hereinafter referred to as “second current collecting wiring end”) 17b of the current collecting wiring 17 is connected to a position outside the sealing portion 60 on the electrode 12A.

  As shown in FIG. 2, the counter substrate 50 includes a metal substrate 51 that also serves as a substrate and an electrode, and a catalyst layer 52 that is provided on the electrode 12 </ b> A side of the metal substrate 51 and contributes to the reduction of the electrolyte 80.

  As shown in FIGS. 2 and 4, the metal substrate 51 and the connection terminal 16 provided on the cell installation surface 11 b side of the transparent substrate 11 and outside the sealing portion 60 are connected by a conductive member 90. . The conductive member 90 has a main body portion 90a and at least one (three in the figure) wiring portions 90b that connect the main body portion 90a and the connection terminal 16.

2 and 4, the conductive member 90 with respect to the area (hereinafter referred to as “power generation area”) W (unit: mm ² ) of the surface 13 a of the oxide semiconductor layer 13 on the transparent substrate 11 side, The area ratio (A / W) of the area 90A (unit: mm ² ) of the interface 90A with the metal substrate 51 (hereinafter referred to as “conductive member contact area”) is 0.029 or more. In FIG. 4, the shaded portion does not indicate the cross section of the conductive member 90 but indicates the interface 90A.

  As shown in FIG. 5, the insulating layer 70 has an inner insulating layer 70 a on the inner side of the outer peripheral edge 70 c of the sealing portion 60 when the photoelectric conversion element 100 is viewed in a direction orthogonal to the cell installation surface 11 b of the transparent substrate 11. And an outer insulating layer 70b outside the outer peripheral edge 70c of the sealing portion 60. The inner insulating layer 70 a is provided in contact with the oxide semiconductor layer 13. That is, the inner insulating layer 70a covers not only the groove 40 but also the entire electrode 12A on the inner side of the outer peripheral edge 70c of the sealing portion 60 in order to suppress moisture intrusion from the groove 40 into the photoelectric conversion cell 20. . In addition, the inner insulating layer 70 b enters the groove 40 in a portion overlapping with the groove 40 in order to more sufficiently suppress the intrusion of moisture from the groove 40 into the photoelectric conversion cell 20. The outer insulating layer 70b includes a connection terminal-external connection terminal region 101 between the first external connection terminal 15a and the connection terminal 16 in the transparent conductive layer 12, and the second external connection terminal 15b and the first current collector. It is provided so as to cover an area other than the area 102 between the wiring end 17a and the wiring-external connection terminal. Accordingly, the region 103 between the external connection terminals between the first external connection terminal 15 a and the second external connection terminal 15 b in the region outside the sealing portion 60 on the cell installation surface 11 b of the transparent substrate 11 is the insulating layer 70. The outer insulating layer 70b is covered with the outer insulating layer 70b. In addition, the region 104 between the connection terminal 16 and the first current collector wiring end 17 a in the region outside the sealing portion 60 on the cell installation surface 11 b of the transparent substrate 11 is also outside the insulating layer 70. It is covered with an insulating layer 70b.

  As shown in FIG. 1, the protective layer 30 covers not only the photoelectric conversion cell 20 but also a region other than the first external connection terminal 15 a and the second external connection terminal 15 b in the region on the transparent substrate 11. . That is, the protective layer 30 includes the outer insulating layer 70b of the insulating layer 70, the connection terminal-external connection terminal region 101, the wiring-external connection terminal region 102, the external connection terminal region 103, and the wiring-connection terminal region. 104 is also covered.

  According to the photoelectric conversion element 100, since the area ratio (A / W) of the conductive member contact area A to the power generation area W is 0.029 or more, the conductive member 90 faces even when the ambient humidity increases. It becomes difficult to peel the substrate 50 from the metal substrate 51, and an increase in contact resistance between the conductive member 90 and the metal substrate 51 is sufficiently suppressed, and a decrease in current is suppressed. Therefore, the photoelectric conversion element 100 can have excellent moisture resistance.

  Next, the transparent substrate 11, the transparent conductive layer 12, the oxide semiconductor layer 13, the first external connection terminal 15 a and the second external connection terminal 15 b, the connection terminal 16, the current collector wiring 17, the dye, the protective layer 30, and the counter substrate 50 The sealing part 60, the insulating layer 70, the electrolyte 80, and the conductive member 90 will be described in detail.

<Transparent substrate>
The material which comprises the transparent substrate 11 should just be a transparent material, for example, As such a transparent material, glass, such as borosilicate glass, soda lime glass, white plate glass, quartz glass, polyethylene terephthalate (PET), for example , Polyethylene naphthalate (PEN), polycarbonate (PC), and polyethersulfone (PES). The thickness of the transparent substrate 11 is appropriately determined according to the size of the photoelectric conversion element 100 and is not particularly limited, but may be in the range of 50 to 10,000 μm, for example.

<Transparent conductive layer>
Examples of the material contained in the transparent conductive layer 12 include conductive metal oxides such as tin-added indium oxide (ITO), tin oxide (SnO ₂ ), and fluorine-added tin oxide (FTO). The transparent conductive layer 12 may be a single layer or a laminate of a plurality of layers containing different conductive metal oxides. When the transparent conductive layer 12 is composed of a single layer, the transparent conductive layer 12 preferably includes FTO because it has high heat resistance and chemical resistance. The transparent conductive layer 12 may further include a glass frit. The thickness of the transparent conductive layer 12 may be in the range of 0.01 to 2 μm, for example.

<Oxide semiconductor layer>
The oxide semiconductor layer 13 is composed of oxide semiconductor particles. Examples of the oxide semiconductor particles include titanium oxide (TiO ₂ ), silicon oxide (SiO ₂ ), zinc oxide (ZnO), tungsten oxide (WO ₃ ), niobium oxide (Nb ₂ O ₅ ), and strontium titanate (SrTiO ₃ ). , Tin oxide (SnO ₂ ), indium oxide (In ₃ O ₃ ), zirconium oxide (ZrO ₂ ), thallium oxide (Ta ₂ O ₅ ), lanthanum oxide (La ₂ O ₃ ), yttrium oxide (Y ₂ O ₃ ) , Holmium oxide (Ho ₂ O ₃ ), bismuth oxide (Bi ₂ O ₃ ), cerium oxide (CeO ₂ ), aluminum oxide (Al ₂ O ₃ ), or two or more thereof.

  The oxide semiconductor layer 13 is usually composed of an absorption layer for absorbing light, but may be composed of an absorption layer and a reflective layer that reflects light transmitted through the absorption layer and returns it to the absorption layer.

  Although the thickness of the oxide semiconductor layer 13 is not specifically limited, Usually, what is necessary is just to be 0.5-50 micrometers.

<First external connection terminal and second external connection terminal>
The first external connection terminal 15a and the second external connection terminal 15b include a metal material. Examples of the metal material include silver, copper, and indium. You may use these individually or in combination of 2 or more types. The first external connection terminal 15a and the second external connection terminal 15b are made of a sintered body made of only a metal material, for example.

<Connection terminal>
The connection terminal 16 includes a metal material. The connection terminal 16 may be made of the same material as the first external connection terminal 15a and the second external connection terminal 15b or may be made of a different material, but is preferably made of the same material.

<Current collection wiring>
The current collection wiring 17 contains a metal material. The current collecting wiring 17 may be made of the same material as the first external connection terminal 15a and the second external connection terminal 15b or may be made of a different material, but is preferably made of the same material.

<Dye>
Examples of the dye include a photosensitizing dye such as a ruthenium complex having a ligand containing a bipyridine structure, a terpyridine structure, or the like, an organic dye such as porphyrin, eosin, rhodamine, or merocyanine, and an organic- Examples include inorganic composite dyes. For example, CH ₃ NH ₃ PbX ₃ (X = Cl, Br, I) is used as the lead halide perovskite. Here, when using a photosensitizing dye as a dye, the photoelectric conversion element 100 becomes a dye-sensitized photoelectric conversion element, and the photoelectric conversion cell 20 becomes a dye-sensitized photoelectric conversion cell.

  Among the above dyes, a photosensitizing dye composed of a ruthenium complex having a ligand containing a bipyridine structure or a terpyridine structure is preferable. In this case, the photoelectric conversion characteristics of the photoelectric conversion element 100 can be further improved.

<Protective layer>
The protective layer 30 only needs to have a resin layer made of a resin material (insulating material) on the transparent substrate 11 side in order to prevent a short circuit with the wiring-external connection terminal region 102. Therefore, the protective layer 30 may be composed of only one resin layer made of a resin material, or may be composed of a laminate of a plurality of resin layers made of a resin material. The protective layer 30 may further include a metal layer or the like on the opposite side of the transparent substrate 11 with respect to the resin layer. The resin material included in the protective layer 30 is not particularly limited as long as it has insulating properties. Examples of the resin material include polyimide resin, epoxy resin, polyurethane resin, acrylic urethane resin, and polyethylene terephthalate (PET) resin. Of these, polyimide resin is preferred. In this case, the region under the protective layer 30 is excellent in concealing property, and more excellent insulating properties can be imparted to the protective layer 30.

  The color of the protective layer 30 is not particularly limited, but at least the layer on the transparent substrate 11 side is preferably black. In this case, if at least the layer on the transparent substrate 11 side of the protective layer 30 is black, even if the ultraviolet ray is irradiated from the protective layer 30 side, the photoelectric conversion element 100 is hardly deteriorated or the heat radiation is increased. Thus, the heat generated in the photoelectric conversion cell 20 is likely to be released.

  Although the thickness of the protective layer 30 is not specifically limited, It is preferable that it is 0.025-0.1 mm. In this case, it is possible to achieve both the difficulty in peeling off the protective layer 30 and the concealing property of the region under the protective layer 30.

<Counter substrate>
As described above, the counter substrate 50 includes the metal substrate 51 serving as a substrate and an electrode, and the catalyst layer 52.

(Metal substrate)
Although the metal substrate 51 should just be comprised with a metal, it is preferable that this metal is a metal which can form a passive state. In this case, since the metal substrate 51 is less likely to be corroded by the electrolyte 80, the photoelectric conversion element 100 can have more excellent durability. Examples of the metal capable of forming a passive material include titanium, nickel, molybdenum, tungsten, aluminum, stainless steel, and alloys thereof. The thickness of the metal substrate 51 is appropriately determined according to the size of the photoelectric conversion element 100 and is not particularly limited, but may be, for example, 0.005 to 0.1 mm.

(Catalyst layer)
The catalyst layer 52 is composed of platinum, a carbon-based material, a conductive polymer, or the like. Here, carbon black and carbon nanotubes are preferably used as the carbon-based material.

<Sealing part>
As a material constituting the sealing portion 60, for example, an ionomer, an ethylene-vinyl acetic anhydride copolymer, an ethylene-methacrylic acid copolymer, an ethylene-vinyl alcohol copolymer, a modified polyolefin resin, an ultraviolet curable resin, And resin, such as a vinyl alcohol polymer, is mentioned. These resins can be used alone or in combination of two or more.

  Although the thickness of the sealing part 60 is not specifically limited, Usually, it is 5-50 micrometers, Preferably it is 10-45 micrometers. In this case, the penetration of water into the inside of the sealing portion 60 can be more sufficiently suppressed.

<Insulating layer>
The insulating layer 70 only needs to be made of an insulating material. Examples of such an insulating material include a resin and an inorganic insulating material, and among them, an inorganic insulating material is preferable. In this case, the insulating layer 70 covers not only the groove 40 but also the entire electrode 12A inside the outer peripheral edge 70c of the sealing portion 60, and the inorganic material has a sealing ability higher than that of the resin. Invasion of moisture can be more sufficiently suppressed. Examples of the inorganic insulating material include glass.

  The insulating material constituting the insulating layer 70 is preferably colored. In this case, when the photoelectric conversion element 100 is viewed from the light receiving surface 11a side, it is possible to sufficiently suppress the counter substrate 50 from being noticeable. For this reason, a favorable external appearance can be realized. Moreover, since it is not necessary to color electrode 12A, the fall of the photoelectric conversion characteristic of the photoelectric conversion element 100 can fully be suppressed. As the colored insulating material, for example, an inorganic insulating material such as colored glass is used.

  When the insulating layer 70 is colored, the color is not particularly limited, and various colors can be used depending on the purpose.

  Although the thickness of the insulating layer 70 is not specifically limited, Usually, it is 10-30 micrometers, Preferably it is 15-25 micrometers.

<Electrolyte>
The electrolyte 80 includes a redox couple and an organic solvent. As the organic solvent, acetonitrile, methoxyacetonitrile, methoxypropionitrile, propionitrile, ethylene carbonate, propylene carbonate, diethyl carbonate, γ-butyrolactone, valeronitrile, pivalonitrile and the like can be used. Examples of the redox pair include iodide ions / polyiodide ions (for example, I ⁻ / I ₃ ⁻ ), and redox pairs such as bromide ions (bromine ions) / polybromide ions, zinc complexes, iron complexes, and cobalt complexes. It is done. The iodide ion / polyiodide ion can be formed by iodine (I ₂ ) and a salt (ionic liquid or solid salt) containing iodide (I ⁻ ) as an anion. When using an ionic liquid having an iodide as an anion, only iodine should be added. When using an ionic liquid other than an organic solvent or an anion as an anion, an anion such as LiI or tetrabutylammonium iodide is used. A salt containing iodide (I ⁻ ) may be added.

  The electrolyte 80 may be an ionic liquid instead of the organic solvent. As the ionic liquid, for example, a known iodine salt such as a pyridinium salt, an imidazolium salt, or a triazolium salt, and a room temperature molten salt that is in a molten state near room temperature is used. Examples of such room temperature molten salts include 1-hexyl-3-methylimidazolium iodide, 1-ethyl-3-propylimidazolium iodide, dimethylimidazolium iodide, ethylmethylimidazolium iodide, and dimethylpropyl. Imidazolium iodide, butylmethylimidazolium iodide, or methylpropylimidazolium iodide is preferably used.

  In addition, the electrolyte 80 may be a mixture of the ionic liquid and the organic solvent instead of the organic solvent.

An additive can be added to the electrolyte 80. As the _{additive, LiI, I 2, 4-} t- butylpyridine, guanidinium thiocyanate, 1-methylbenzimidazole, 1-butyl-benzimidazole and the like.

Further, as the electrolyte 80, a nanocomposite gel electrolyte, which is a pseudo-solid electrolyte obtained by kneading nanoparticles such as SiO ₂ , TiO ₂ , and carbon nanotubes with the electrolyte, may be used, or polyvinylidene fluoride. Alternatively, an electrolyte gelled with an organic gelling agent such as a polyethylene oxide derivative or an amino acid derivative may be used.

The electrolyte 80 preferably includes an oxidation-reduction pair composed of iodide ions / polyiodide ions (for example, I ⁻ / I ₃ ⁻ ), and the concentration of polyiodide ions is preferably 0.006 mol / liter or less. In this case, since the concentration of polyiodide ions that carry electrons is low, the leakage current can be further reduced. For this reason, since an open circuit voltage can be increased more, a photoelectric conversion characteristic can be improved more. In particular, the concentration of polyiodide ions is preferably 0.005 mol / liter or less, more preferably 0 to 6 × 10 ⁻⁶ mol / liter, and 0 to 6 × 10 ⁻⁸ mol / liter. Is more preferable. In this case, when the photoelectric conversion element 100 is viewed from the light receiving surface 11a side of the transparent substrate 11, the color of the electrolyte 80 can be made inconspicuous.

<Conductive member>
The area ratio (A / W) is not particularly limited as long as it is 0.029 or more, but is preferably 0.150 or more. In this case, the photoelectric conversion element 100 can have better moisture resistance than the case where the area ratio (A / W) is less than 0.150. The area ratio (A / W) is more preferably 0.180 or more.

  However, the area ratio (A / W) is preferably 0.620 or less. In this case, even if the conductive member 90 expands and contracts in the in-plane direction of the metal substrate 51 as the ambient temperature changes, the conductive member 90 is not the metal substrate compared to the case where the area ratio A / W exceeds 0.620. It becomes difficult to expand and contract in the in-plane direction of 51. For this reason, in the photoelectric conversion cell 20, when the conductive member 90 expands and contracts in the in-plane direction of the metal substrate 51, it is sufficiently suppressed that the counter substrate 50 is separated from the electrode 12A, and the distance between the counter substrate 50 and the electrode 12A. The increase in internal resistance is sufficiently suppressed. As a result, the photoelectric conversion element 100 can have excellent durability against temperature changes.

  The area ratio (A / W) is more preferably 0.330 or less.

  The conductive member 90 includes a metal material. As the metal material, for example, silver or copper can be used. The conductive member 90 may further include a binder resin in addition to the metal material. Examples of the binder resin include an epoxy resin, a polyester resin, and an acrylic resin. Of these, epoxy resins and polyester resins are preferred because they are less likely to thermally expand even at high temperatures and the resistance change with time can be further reduced.

  The main body portion 90a of the conductive member 90 may be formed of a laminate having a first layer directly connected to the metal substrate 51 and a second layer provided on the first layer. In this case, the first layer includes a metal material, a binder resin, and carbon, the second layer includes a metal material and a binder resin, and the carbon content in the first layer is the carbon content in the second layer. It is preferable that it is larger than the rate. In this case, the conductive member 90 is difficult to peel from the metal substrate 51.

  Next, a method for manufacturing the photoelectric conversion element 100 will be described with reference to FIGS. 1 and 3 to 6. FIG. 6 is a cross-sectional view showing a structure obtained in the middle of the method for manufacturing the photoelectric conversion element of FIG.

  First, a laminate formed by forming a transparent conductive film on the cell installation surface 11b of one transparent substrate 11 is prepared.

  As a method for forming the transparent conductive film, sputtering, vapor deposition, spray pyrolysis, CVD, or the like is used.

  Next, as shown in FIG. 3, grooves 40 are formed in the transparent conductive film, and the transparent conductive layer 12 is formed. At this time, the transparent conductive layer 12 is formed such that the electrode 12A, the first current extraction unit 12B, the separation unit 12C, and the second current extraction unit 12D are formed.

The groove 40 can be formed by a laser scribing method using, for example, a YAG laser or a CO ₂ laser as a light source.

  Next, the precursor of the first external connection terminal 15a and the precursor of the connection terminal 16 are formed on the first current extraction portion 12B so as to be separated from each other. The precursor of the first external connection terminal 15a and the precursor of the connection terminal 16 can be formed, for example, by applying a silver paste and drying.

  Further, a precursor of the second external connection terminal 15b is formed on the second current extraction portion 12D. The precursor of the second external connection terminal 15b can be formed, for example, by applying a silver paste and drying it.

  Moreover, the precursor of the current collection wiring 17 is formed so that it may straddle the electrode 12A and the 2nd electric current extraction part 12D. At this time, one end of the precursor of the current collector wiring 17 is disposed on the second current extraction portion 12D at a position separated from the precursor of the second external connection terminal 15b, and the other end is on the electrode 12A. It is formed so that it may be arranged at the position. The precursor of the current collecting wiring 17 can be formed, for example, by applying a silver paste and drying it.

  Next, in the transparent conductive layer 12, a region where the oxide semiconductor layer 13 is to be formed (hereinafter referred to as "semiconductor layer formation planned region"), a region 101 between the connection terminal and the external connection terminal, and a wiring- The precursor of the insulating layer 70 is formed so as to cover a region other than the connection terminal region 102. At this time, the precursor of the insulating layer 70 is formed so as to enter the groove 40. The precursor of the insulating layer 70 can be formed, for example, by applying and drying a paste containing an inorganic insulating material.

  Next, the precursor of the first external connection terminal 15a, the precursor of the second external connection terminal 15b, the precursor of the connection terminal 16, the precursor of the current collecting wiring 17, and the precursor of the insulating layer 70 are baked together. The first external connection terminal 15a, the second external connection terminal 15b, the connection terminal 16, the current collecting wiring 17 and the insulating layer 70 are formed.

  At this time, although the firing temperature varies depending on the type of insulating material, etc., it is usually 350 to 600 ° C., and the firing time also varies depending on the type of insulating material, but is usually 1 to 5 hours.

  Next, a precursor of the oxide semiconductor layer 13 is formed on the semiconductor layer formation scheduled region of the electrode 12A.

  The precursor of the oxide semiconductor layer 13 is obtained by printing and drying an oxide semiconductor layer paste for forming the oxide semiconductor layer 13. In addition to titanium oxide, the oxide semiconductor layer paste includes a resin such as polyethylene glycol and ethyl cellulose and a solvent such as terpineol.

  As a printing method of the oxide semiconductor layer paste, for example, a screen printing method, a doctor blade method, a bar coating method, or the like can be used.

  Next, the precursor of the oxide semiconductor layer 13 is fired to form the oxide semiconductor layer 13.

  At this time, although the firing temperature varies depending on the type of oxide semiconductor particles, it is usually 350 to 600 ° C., and the firing time also varies depending on the type of oxide semiconductor particles, but is usually 1 to 5 hours.

  Thus, the structure A is obtained as shown in FIG.

  Next, a sealing part forming body for forming the sealing part 60 is prepared. The sealing part forming body can be obtained, for example, by preparing one sealing resin film made of a material constituting the sealing part 60 and forming an opening in the sealing resin film.

  And as shown in FIG. 5, this sealing part formation body is adhere | attached on the structure A. As shown in FIG. At this time, the sealing portion forming body is bonded to the structure A so as to overlap with the insulating layer 70 and the oxide semiconductor layer 13 is disposed inside. Adhesion of the sealing portion forming body to the structure A can be performed by, for example, heating and melting the sealing portion forming body.

  Next, a dye is supported on the oxide semiconductor layer 13 of the structure A. For this purpose, for example, the structure A is immersed in a dye solution containing a dye, the dye is adsorbed on the oxide semiconductor layer 13, and then the excess dye is washed away with the solvent component of the solution and dried. Just do it.

  Next, the electrolyte 80 is disposed on the oxide semiconductor layer 13.

  On the other hand, a counter substrate 50 is prepared. The counter substrate 50 can be obtained, for example, by forming a conductive catalyst layer 52 on the metal substrate 51.

  Next, another sealing part forming body described above is prepared. And the opposing board | substrate 50 is bonded together so that the opening of a sealing part formation body may be plugged up.

  Next, the sealing portion forming body bonded to the counter substrate 50 and the sealing portion forming body bonded to the structure A in which the electrolyte 80 is arranged are overlapped, and the sealing portion forming body is heated and melted while being pressurized. . Thus, the sealing portion 60 is formed between the transparent substrate 11 and the counter substrate 50 of the structure A. The formation of the sealing portion 60 may be performed under atmospheric pressure or under reduced pressure, but is preferably performed under reduced pressure.

  Then, as shown in FIG. 4, the connection terminal 16 and the metal substrate 51 of the counter substrate 50 are connected by a conductive member 90.

  At this time, the conductive member 90 prepares a paste containing a metal material constituting the conductive member 90, and this paste is connected to the metal substrate 51 of the counter substrate 50, the connection terminal 16, and the first current extraction portion 12B. Apply to and cure. As the paste, it is preferable to use a low-temperature curable paste that can be cured at a temperature of 90 ° C. or lower from the viewpoint of avoiding adverse effects on the dye supported on the oxide semiconductor layer 13. At this time, the conductive member 90 is formed so that the area ratio (A / W) is 0.029 or more.

  Finally, the protective layer 30 is formed. The protective layer 30 is formed so as to cover not only the photoelectric conversion cell 20 but also a region other than the first external connection terminal 15 a and the second external connection terminal 15 b in the region on the transparent substrate 11. That is, the protective layer 30 includes not only the photoelectric conversion cell 20 but also the outer insulating layer 70b of the insulating layer 70, the connection terminal-external connection terminal region 101, the wiring-external connection terminal region 102, the external connection terminal region 103, And it forms so that the area | region 104 between wiring-connection terminals may also be covered.

  The photoelectric conversion element 100 is obtained as described above (see FIG. 1).

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the protective layer 30 has a resin layer made of a resin material (insulating material) on the transparent substrate 11 side in order to prevent a short circuit with the wiring-external connection terminal region 102. When the external connection terminal region 102 is covered with the insulating layer 70, the protective layer 30 may have a conductive layer such as a metal layer on the transparent substrate 11 side.

  Moreover, in the said embodiment, although the photoelectric conversion element 100 has the protective layer 30, the photoelectric conversion element 100 does not need to have the protective layer 30. FIG.

  In the above embodiment, the insulating layer 70 covers the entire electrode 12 </ b> A inside the outer peripheral edge of the sealing portion 60. However, the insulating layer 70 is a part of the electrode 12 </ b> A inside the outer peripheral edge of the sealing portion 60. May only cover.

  Moreover, in the said embodiment, although the insulating layer 70 is comprised by the inner side insulating layer 70a and the outer side insulating layer 70b, the insulating layer 70 may be comprised only by the inner side insulating layer 70a.

  Furthermore, in the said embodiment, although the photoelectric conversion element 100 has the insulating layer 70, it does not need to have the insulating layer 70. FIG.

  Moreover, in the said embodiment, although the photoelectric conversion element 100 has the current collection wiring 17, the photoelectric conversion element of this invention does not necessarily need to have the current collection wiring 17. FIG.

  Further, in the above embodiment, the separation part 12C is provided on the transparent substrate 11 so as to surround the electrode 12A and the second current extraction part 12D, but the separation part 12C is provided on the transparent substrate 11. It does not have to be.

  Furthermore, in the said embodiment, although only one photoelectric conversion cell 20 is provided on the cell installation surface 11b of the transparent substrate 11, in the photoelectric conversion element 100, several photoelectric conversion cells 20 are provided on the transparent substrate 11. FIG. May be. In this case, the plurality of photoelectric conversion cells 20 may be connected in series or may be connected in parallel. When the plurality of photoelectric conversion cells 20 are connected in series, the first current extraction unit 12B is connected to the counter substrate 50 of the photoelectric conversion cell 20 on one end side of the plurality of photoelectric conversion cells 20, and the second current extraction. The part 12D is connected to the electrode 12A of the photoelectric conversion cell 20 on the other end side. When the plurality of photoelectric conversion cells 20 are connected in parallel, the first current extraction unit 12B is connected to the counter substrate 50 of all the photoelectric conversion cells 20 among the plurality of photoelectric conversion cells 20 by the conductive member 90. The second current extraction unit 12 </ b> D is connected to the electrodes 12 </ b> A of all the photoelectric conversion cells 20 among the plurality of photoelectric conversion cells 20.

  Hereinafter, the content of the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

Example 1
First, a laminate was prepared by forming a transparent conductive film made of FTO having a thickness of 0.7 μm on a transparent substrate made of alkali-free glass and having a size of 112 mm × 56 mm and a thickness of 2.2 mm. Next, as shown in FIG. 3, a groove 40 was formed in the transparent conductive film by a YAG laser, and the transparent conductive layer 12 was formed. At this time, the transparent conductive layer 12 was formed such that the electrode 12A, the first current extraction unit 12B, the separation unit 12C, and the second current extraction unit 12D were formed. At this time, the width of the groove 40 was set to 0.1 mm. The electrode 12A was formed to have a square shape of 54.4 mm × 104.5 mm, and the second current extraction portion 12D was formed to extend from one side of the electrode 12A and to have a square shape. The length in the extending direction of the second current extraction portion 12D was 4.3 mm, and the width of the second current extraction portion 12D was 27.2 mm.

  The first current extraction portion 12B was formed to have a size of 27.2 mm × 4.3 mm.

  Next, the precursor of the first external connection terminal 15a and the precursor of the connection terminal 16 were formed in a rectangular shape and spaced apart from each other on the first current extraction portion 12B. At this time, the precursor of the first external connection terminal 15a was formed to have a size of 8 mm × 1.8 mm, and the precursor of the connection terminal 16 was formed to have a size of 8 mm × 0.3 mm.

  In addition, a precursor of the second external connection terminal 15b was formed in a rectangular shape on the second current extraction portion 12D. At this time, the precursor of the second external connection terminal 15b was formed to have a size of 8 mm × 1.8 mm.

  Moreover, the current collection wiring 17 was formed so that it might straddle the 2nd electric current extraction part 12D and the electrode 12A. At this time, one end of the precursor of the current collector wiring 17 is disposed on the second current extraction portion 12D at a position separated from the precursor of the second external connection terminal 15b. The precursor of current collection wiring 17 was formed so that an end might be arranged so that it may be arranged in the position on electrode 12A. Further, the precursor of the current collecting wiring 17 has an L-shaped portion having a width of 0.3 mm × length of 21.6 mm and a portion having a width of 0.3 mm × length of 105.1 mm. Formed as follows. The precursor of the connection terminal 16, the precursor of the first external connection terminal 15a, the precursor of the second external connection terminal 15b, and the precursor of the current collector wiring 17 were formed by applying a silver paste and drying.

  Next, in the transparent conductive layer 12, a region other than the semiconductor layer formation planned region (47.2 mm × 102.1 mm region), the connection terminal-external connection terminal region 101, and the wiring-external connection terminal region 102. The precursor of the insulating layer 70 was formed so as to cover the surface. At this time, the precursor of the insulating layer 70 was formed so as to enter the groove 40. The precursor of the insulating layer 70 was formed by applying and drying a paste containing glass frit (trade name “PLFOC-837B”, manufactured by Okuno Pharmaceutical Co., Ltd.).

  Next, the precursor of the first external connection terminal 15a, the precursor of the second external connection terminal 15b, the precursor of the connection terminal 16, the precursor of the current collecting wiring 17, and the precursor of the insulating layer 70 are baked together. The first external connection terminal 15a, the second external connection terminal 15b, the connection terminal 16, the current collecting wiring 17 and the insulating layer 70 were formed. At this time, the firing temperature was 500 ° C., and the firing time was 1 hour. At this time, the distance L between the first external connection terminal 15a and the connection terminal 16 was 0.5 mm. Further, the distance L ′ between the second external connection terminal 15b and the first current collector wiring end 17a was 0.5 mm.

  Furthermore, a precursor of the oxide semiconductor layer 13 was formed on the semiconductor layer formation scheduled region of the electrode 12A. At this time, the precursor of the oxide semiconductor layer 13 was obtained by applying a paste containing titanium oxide so as to fill the inside of the insulating layer 70 by screen printing and drying at 150 ° C. for 10 minutes.

Next, the precursor of the oxide semiconductor layer 13 was fired to form the oxide semiconductor layer 13. At this time, the firing temperature was 500 ° C., and the firing time was 1 hour. Thus, Structure A was obtained. In the obtained structure A, the power generation area W was 102.10 mm × 47.20 mm = 4819.12 mm ² .

  Next, the sealing part formation body for forming a sealing part was prepared. The sealing part forming body is prepared by preparing a sealing resin film made of 51.2 mm × 106.1 mm × 35 μm maleic anhydride-modified polyethylene (trade name “Binell”, manufactured by DuPont). It was obtained by forming one rectangular opening of 102.10 mm × 47.20 mm on the resin film for use.

  And after this sealing part formation body was piled up on structure A, it was made to adhere to insulating layer 70 on structure A by heating and melting the sealing part formation body. At this time, the sealing portion forming body was bonded to the structure A so as to overlap the insulating layer 70 and to be disposed between the oxide semiconductor layer 13, the connection terminal 16, and the current collector wiring 17.

  Next, the structure A obtained as described above is mixed by containing 0.2 mM of a photosensitizing dye composed of Z907, mixing a solvent with acetonitrile and tert-butanol at a volume ratio of 1: 1. After being immersed in a dye solution as a solvent for a whole day and night, it was taken out and dried, and a photosensitizing dye was supported on the oxide semiconductor layer.

Then, a mixture of dimethylpropyl imidazolium iodide and 3-methoxy propionitrile, I _2, was prepared electrolyte 80 obtained by adding methyl benzimidazole, butyl benzimidazole, a guanidinium thiocyanate and t- butylpyridine . Then, the electrolyte 80 was dropped onto the oxide semiconductor layer 13 and applied, and the electrolyte 80 was disposed.

  Next, one counter substrate 50 was prepared. The counter substrate 50 was prepared by forming a catalyst layer made of platinum having a thickness of 5 nm on a 51.2 mm × 106.1 mm × 40 μm titanium foil by sputtering. In addition, another sealing part forming body was prepared. And the opposing board | substrate 50 was bonded together so that the opening of a sealing part formation body might be plugged up.

  And the sealing part formation body adhere | attached on the opposing board | substrate 50 and the sealing part formation body adhere | attached on the structure A in which the electrolyte 80 is arrange | positioned are piled up under reduced pressure, and it heats, pressurizing a sealing part formation body Melted. Thus, a sealing portion was formed between the structure A and the counter substrate. At this time, the thickness of the sealing part was 40 μm, and the width of the sealing part was 2 mm.

  Next, the connection terminal 16 and the metal substrate 51 of the counter substrate 50 were connected by the conductive member 90 as follows.

  That is, first, silver particles (average particle size: 3.5 μm), carbon (average particle size: 500 nm), and polyester resin were dispersed in a solvent composed of diethylene glycol monoethyl ether acetate to prepare a first conductive paste. At this time, the silver particles, carbon, polyester resin, and solvent were mixed at a mass ratio of 70: 1: 10: 19.

  On the other hand, silver particles (average particle size: 2 μm) and polyester resin were dispersed in a solvent composed of ethylene glycol monobutyl ether to prepare a second conductive paste. At this time, the silver particles, the polyester resin, and the solvent were mixed at a mass ratio of 65:10:25.

And the said 1st conductive paste was apply | coated on the metal substrate 51, and a part of precursor of the main-body part 90a was formed. Thereafter, the second conductive paste is applied onto a part of the precursor of the main body 92, and the connection terminal 16 on the first current extraction part 12B is connected to a part of the precursor of the main body 92. It was applied as follows. Thus, a precursor of the conductive member 90 was formed. Then, the conductive member 90 was formed by heating and curing the precursor of the conductive member 90 at 85 ° C. for 12 hours. Thus, a conductive member 90 composed of the main body 90a and the three wiring portions 90b was formed. At this time, the main body portion 90a is formed to have a size of 41.2 mm × 4.5 mm × thickness 60 μm when viewed in a direction perpendicular to the cell installation surface 11b of the transparent substrate 11, and the three wirings Each part 90b was formed to have dimensions of 3.7 mm × 2.0 mm × thickness 30 μm. At this time, the conductive member contact area A is 3.7 × 2.0 × 3 + 4.5 × 41.2 = 207.6 mm ² , and the conductive member has an area ratio (A / W) of 0.043. 90 was formed.

  Next, the protective layer 30 was formed by applying a paint containing an acrylic urethane resin (trade name “RECRACK 110”, manufactured by Fujikura Kasei Co., Ltd.) with a slit coater and drying at 80 ° C. for 30 minutes. At this time, the protective layer 30 was formed so as to cover not only the photoelectric conversion cell 20 but also the region on the transparent substrate 11 other than the first external connection terminal 15a and the second external connection terminal 15b. That is, the protective layer 30 includes not only the photoelectric conversion cell 20 but also the outer insulating layer 70b of the insulating layer 70, the connection terminal-external connection terminal region 101, the wiring-external connection terminal region 102, the external connection terminal region 103, And it formed so that the area | region 104 between wiring-connection terminals might also be covered. The photoelectric conversion element 100 was obtained as described above.

(Examples 2 to 10 and Comparative Examples 1 to 4)
A photoelectric conversion element was produced in the same manner as in Example 1 except that the values of the power generation area W and the conductive member contact area A were as shown in Table 1 and A / W was as shown in Table 1.

[Characteristic evaluation]
The photoelectric conversion elements of Examples 1 to 10 and Comparative Examples 1 to 4 obtained as described above were evaluated for moisture resistance and durability against temperature changes as follows.
(Moisture resistance)
About the photoelectric conversion element of Examples 1-10 obtained as mentioned above and Comparative Examples 1-4, light of 200 lux was irradiated from white LED, and the power generation performance (maximum output) W1 was measured. Thereafter, a temperature and humidity cycle test (−40 / 85 ° C., 85% RH) according to JIS C 8938 was performed, and the power generation performance (maximum output) W2 was measured again for the photoelectric conversion element in the same manner as described above. At this time, the temperature / humidity cycle test was performed 10 cycles with room temperature → −40 ° C. → 85 ° C. → room temperature as one cycle. In this temperature and humidity cycle, the humidity was set to 85% RH at a high temperature (85 ° C.). The power generation performance was measured by connecting the two terminals of the measuring instrument to the first external connection terminal 15a and the second external connection terminal 15b of the photoelectric conversion element. And the maximum output residual rate was computed based on the following formula using the result of the maximum output before and after a temperature / humidity cycle test. The results are shown in Table 1.

Maximum output remaining rate (%) = 100 × W2 / W1

The acceptance criteria for moisture resistance were as follows.
(Acceptance criteria) The maximum output remaining rate after the temperature and humidity cycle test is 90% or more.

(Durability against temperature changes)
About the photoelectric conversion element of Examples 1-10 obtained as mentioned above and Comparative Examples 1-4, the light of 200 lux was irradiated from white LED, and the power generation performance (maximum output) W3 was measured. Then, the temperature cycle test (-40-85 degreeC) according to JISC8938 was done, and the electric power generation performance (maximum output) W4 was measured again about the photoelectric conversion element like the above. At this time, the temperature cycle test was performed 200 cycles with room temperature → −40 ° C. → 85 ° C. → room temperature as one cycle. The power generation performance was measured in the same manner as in the moisture resistance evaluation. And the maximum output residual rate was computed based on the following formula using the result of the maximum output before and after a temperature cycle test. The results are shown in Table 1.

Maximum output remaining rate (%) = 100 × W4 / W3

The results are shown in Table 1.

  From the results shown in Table 1, it was found that the photoelectric conversion elements of Examples 1 to 10 reached the acceptance standard in terms of moisture resistance. On the other hand, it was found that the photoelectric conversion elements of Comparative Examples 1 to 4 did not reach the acceptance standard in terms of moisture resistance.

  From the above results, it was confirmed that the photoelectric conversion element of the present invention has excellent moisture resistance.

11 ... Transparent substrate 11b ... Cell installation surface (one surface)
DESCRIPTION OF SYMBOLS 12A ... Electrode 13 ... Oxide semiconductor layer 13a ... The surface at the side of the transparent substrate of an oxide semiconductor layer 16 ... Connection terminal 20 ... Photoelectric conversion cell 50 ... Opposite substrate 51 ... Metal substrate 60 ... Sealing part 90 ... Conductive member 90A ... Conductive Interface between member and metal substrate 100 ... Photoelectric conversion element

Claims (2)

A transparent substrate;
A photoelectric conversion element comprising at least one photoelectric conversion cell provided on one surface of the transparent substrate,
The photoelectric conversion cell is
An electrode provided on the one surface of the transparent substrate;
A counter substrate facing the electrode;
An oxide semiconductor layer provided between the electrode and the counter substrate;
An annular sealing portion provided between the transparent substrate and the counter substrate;
The counter substrate has a metal substrate;
The metal substrate of the photoelectric conversion cell and a connection terminal provided on the one surface side of the transparent substrate and outside the sealing portion are connected by a conductive member,
The area ratio (A / W) of the area A (unit: mm ² ) of the interface between the conductive member and the metal substrate to the area W (unit: mm ² ) of the surface of the oxide semiconductor layer on the transparent substrate side. ) Is 0.029 or more.   The photoelectric conversion element according to claim 1, wherein the conductive member contains a resin, and the area ratio (A / W) is 0.620 or less.

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