JP2018037553A - Photoelectric conversion element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion element having superior durability.SOLUTION: A photoelectric conversion element comprises at least one photoelectric conversion cell. The at least one photoelectric conversion cell includes: an electrode substrate; a counter substrate opposed to the electrode substrate; an oxide semiconductor layer provided on the electrode substrate; a pigment adsorbed by the oxide semiconductor layer; an annular sealing part bonding the electrode substrate and the counter substrate to each other and surrounding the oxide semiconductor layer; and an electrolyte filling a cell space formed by the electrode substrate, the counter substrate and the sealing part. The oxide semiconductor layer has an inside portion and an annular outside portion surrounding the inside portion as in plan view of the oxide semiconductor layer from a thickness direction thereof. In plan view of the oxide semiconductor layer from the thickness direction thereof, an adsorption amount of the pigment per unit area in the outside portion is larger than an adsorption amount of the pigment per unit area in the inside portion.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a photoelectric conversion element.

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

  As a photoelectric conversion element using such a dye, for example, a dye-sensitized photoelectric conversion element disclosed in Patent Document 1 below is known. In the following Patent Document 1, a first electrode, a second electrode facing the first electrode, an oxide semiconductor layer provided on the first electrode, an electrolyte provided between the first electrode and the second electrode, An oxide semiconductor layer on the first electrode, the inner part facing the approaching part of the second electrode, and the annular outer part facing the connection part of the second electrode provided around the inner part A dye-sensitized photoelectric conversion element having the following formulas is disclosed.

Japanese Patent No. 5893748

  However, the photoelectric conversion element described in Patent Document 1 described above has room for improvement in terms of durability.

  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 durability.

  The inventor examined the cause of the above problem in the dye-sensitized photoelectric conversion element described in Patent Document 1. As a result, in the dye-sensitized photoelectric conversion element described in Patent Document 1, the dye is desorbed from the oxide semiconductor layer by moisture entering the oxide semiconductor layer through the sealing portion, and the desorption of the dye is the oxide. The present inventor thought that it is particularly likely to occur outside the inside of the semiconductor layer, and this may lead to a decrease in durability of the photoelectric conversion element. Therefore, as a result of further intensive studies, the present inventor has found that the above-described problems can be solved by the following invention.

  That is, the present invention includes at least one photoelectric conversion cell, and the photoelectric conversion cell includes an electrode substrate, a counter substrate facing the electrode substrate, an oxide semiconductor layer provided on the electrode substrate, and the oxidation Formed by a dye adsorbed on the physical semiconductor layer, an annular sealing portion that joins the electrode substrate and the counter substrate and surrounds the oxide semiconductor layer, and the electrode substrate, the counter substrate, and the sealing portion And an electrolyte that fills the cell space, and when the oxide semiconductor layer is viewed in plan in the thickness direction of the oxide semiconductor layer, an inner portion and an annular outer portion that surrounds the inner portion And the amount of the dye adsorbed per unit area in the outer portion is equal to the amount of the dye adsorbed per unit area in the inner portion when the oxide semiconductor layer is viewed in plan in the thickness direction. More than A photoelectric conversion element.

  According to the photoelectric conversion element of the present invention, when the oxide semiconductor layer is planarly viewed in the thickness direction of the oxide semiconductor layer, the amount of dye adsorbed per unit area in the outer portion of the oxide semiconductor layer is in the inner portion. It is larger than the amount of dye adsorbed per unit area. For this reason, even when a part of the dye is detached at the outer part due to the intrusion of moisture, a sufficient amount of dye adsorbed is secured at the outer part, and the light absorption ability is unlikely to decrease. As a result, a decrease in output as the entire photoelectric conversion element is sufficiently suppressed. Therefore, the photoelectric conversion element of the present invention can have excellent durability.

In the above photoelectric conversion element, it is preferable _{R 1} represented by the following formula (1) is from 1.08 to 1.75.

R ₁ = m ₁ / m ₂ (1)
(In the formula (1), m ₁ represents the adsorption amount (mol / m ² ) of the dye per unit area in the outer portion, and m ₂ represents the adsorption amount of the dye per unit area in the inner portion ( mol / m ² ).)

In this case, as compared with the case where R ₁ is outside the above range, the photoelectric conversion element can be both a better durability and better power generation performance.

In the photoelectric conversion element, the outer portion includes a main body portion provided on the electrode substrate and having the same thickness as the inner portion, and a protruding portion protruding from the main body portion toward the counter substrate. and, _{R 2} represented by the following formula (2) is preferably a 0.37 to 5.51.

R ₂ = S ₂ / S ₁ (2)
(In the above formula (2), S ₁ represents the area (cm ² ) of the outer portion in plan view in the thickness direction of the oxide semiconductor layer, and S ₂ represents the thickness direction of the oxide semiconductor layer. (Indicates the area (cm ² ) of the inner part in plan view.)

In this case, the amount of dye adsorbed per unit volume in the outer part, that is, the density of the dye in the outer part, is reduced compared to the case where the outer part does not have a protruding part, so that the dye can absorb light efficiently. Thus, the photoelectric conversion characteristics are further improved. Further, as compared with the case where R ₂ is outside the above range, the photoelectric conversion element can be both a better durability and better power generation performance.

In the above photoelectric conversion element, it is preferable _{R 3} represented by the following formula (3) is 0.63 to 0.95.

R ₃ = d ₂ / d ₁ (3)
(In the above formula (3), d ₁ represents the thickness (μm) of the outer portion, and d ₂ represents the thickness (μm) of the inner portion.)

In this case, in-plane variation of the short-circuit current density can be further reduced as compared with the case where R ₃ is out of the above range, and the change in the power generation characteristics of the photoelectric conversion element due to uneven illuminance can be sufficiently suppressed.

In the above photoelectric conversion element, it is preferable _{R 4} represented by the following formula (4) is 0.17 to 2.69.

R ₄ = S ′ ₁ / S ₂ (4)
(In the above formula (4), S ′ ₁ is a height H (μm) from the interface between the electrode substrate and the oxide semiconductor layer, and the protruding portion of the outer portion is cut along a plane parallel to the interface. and it represents the area of the annular region (cm ²⁾ obtained by the height H ([mu] m) the following formula (5) meet, _{S 2} represents the area (cm ²⁾ of the inner portion.)

H = 1/2 (d ₁ + d ₂ ) (5)
(In the above formula (5), d ₂ represents the thickness (μm) of the inner portion in plan view in the thickness direction of the oxide semiconductor layer.)

In this case, in-plane variation of the short-circuit current density can be further reduced as compared with the case where R ₄ is out of the above range, and the change in the power generation characteristics of the photoelectric conversion element due to uneven illuminance can be sufficiently suppressed.

  In the photoelectric conversion element, the counter substrate connects the annular portion that is joined to the sealing portion, the proximity portion that is closer to the oxide semiconductor layer than the annular portion, and the annular portion and the proximity portion. It is preferable that the outer portion and the proximity portion overlap each other when the outer portion and the proximity portion are viewed in the thickness direction of the oxide semiconductor layer.

  In this case, when the outer portion and the adjacent portion are viewed in the thickness direction of the oxide semiconductor layer, a higher short-circuit current value can be obtained as compared with the case where the outer portion and the adjacent portion do not overlap.

  In the present invention, the “adsorption amount of the dye” refers to the total adsorption amount of the dye adsorbed on the outer side or the inner side of the oxide semiconductor layer in the thickness direction of the oxide semiconductor layer.

  In the present invention, the “outer portion” is an annular shape in which the thickness of the inner portion starts to change from the inner portion toward the peripheral portion of the oxide semiconductor layer when viewed in plan in the thickness direction of the oxide semiconductor layer. A region outside the line or a region outside the annular line where the amount of the dye adsorbed on the oxide semiconductor layer starts to change in the thickness direction of the oxide semiconductor layer.

  Furthermore, in the present invention, “the thickness of the outer portion” refers to the maximum value of the thickness of the outer portion when the thickness of the outer portion is not constant.

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

It is a cut surface end view showing one embodiment of a photoelectric conversion element of the present invention. It is sectional drawing along the II-II line of FIG. It is a cut surface end view which shows other embodiment of the photoelectric conversion element of this invention. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3.

  Hereinafter, an embodiment of the photoelectric conversion element of the present invention will be described in detail with reference to FIGS. 1 and 2. FIG. 1 is a sectional end view showing one embodiment of the photoelectric conversion element of the present invention, and FIG. 2 is a cross-sectional view taken along the line II-II in FIG.

  As shown in FIGS. 1 and 2, the photoelectric conversion element 100 includes one photoelectric conversion cell 60. The photoelectric conversion cell 60 includes an electrode substrate 10, a counter substrate 20 facing the electrode substrate 10, an oxide semiconductor layer 30 provided on the electrode substrate 10, a dye adsorbed on the oxide semiconductor layer 30, and an electrode substrate. 10 and an annular sealing portion 40 that joins the counter substrate 20, and an electrolyte 50 that fills a cell space formed by the electrode substrate 10, the counter substrate 20, and the sealing portion 40.

  The oxide semiconductor layer 30 includes an inner portion 31 and an annular outer portion 32 that surrounds the inner portion 31 when viewed in plan in the thickness direction A of the oxide semiconductor layer 30.

The outer portion 32 is provided on the electrode substrate 10, and has a main body portion 32 b having the same thickness as the inner portion 31, and a protruding portion 32 a that protrudes from the main body portion 32 b toward the counter substrate 20. Here, the thickness of the outer portion 32 is larger than the thickness of the inner portion 31 by the amount of the protruding portion 32a. Therefore, when the oxide semiconductor layer 30 is viewed in plan in the thickness direction A, the dye adsorption amount m ₁ per unit area in the outer portion 32 of the oxide semiconductor layer 30 is adsorbed by the protruding portion 32a. which is greater than the adsorption m ₂ minute only per unit area in the inner portion 31 of the oxide semiconductor layer 30 of a dye.

According to the photoelectric conversion element 100, when the oxide semiconductor layer 30 is viewed in plan in the thickness direction A of the oxide semiconductor layer 30, the amount of dye adsorption m per unit area in the outer portion 32 of the oxide semiconductor layer 30. ₁ is larger than the adsorption amount m ₂ of the dye per unit area in the inner portion 31. For this reason, even when a part of the dye is detached from the outer portion 32 due to the intrusion of moisture, the outer portion 32 has a sufficient amount of dye adsorbed, and the light absorption ability is unlikely to decrease. As a result, a decrease in output as the entire photoelectric conversion element 100 is sufficiently suppressed. Therefore, the photoelectric conversion element 100 can have excellent durability.

  Next, the electrode substrate 10, the dye, the oxide semiconductor layer 30, the counter substrate 20, the sealing portion 40, and the electrolyte 50 will be described in detail.

<Electrode substrate>
The electrode substrate 10 includes a transparent substrate 11 and a transparent conductive layer 12 provided on the transparent substrate 11.

  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 Insulating materials such as 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 a range of 0.05 to 40 mm, for example.

Examples of the material constituting 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 made of different conductive metal oxides. When the transparent conductive layer 12 is composed of a single layer, the transparent conductive layer 12 is preferably composed of FTO because it has high heat resistance and chemical resistance. The thickness of the transparent conductive layer 12 may be in the range of 0.01 to 2 μm, for example.

<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 a photosensitizing dye is used as the dye, the photoelectric conversion element 100 is a dye-sensitized photoelectric conversion element, and the photoelectric conversion cell 60 is 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.

<Oxide semiconductor layer>
The oxide semiconductor layer 30 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 ), or two or more thereof.

  As described above, the oxide semiconductor layer 30 includes the inner portion 31 and the annular outer portion 32 surrounding the inner portion 31 when viewed in plan from the thickness direction of the oxide semiconductor layer 30.

  Here, the outer portion 32 includes a main body portion 32 b provided on the electrode substrate 10 and having the same thickness as the inner portion 31, and a protruding portion 32 a that protrudes from the main body portion 32 b toward the counter substrate 20. Here, the thickness of the outer portion 32 is larger than the thickness of the inner portion 31 by the amount that the outer portion 32 has the protruding portion 32 a.

When the oxide semiconductor layer 30 is viewed in plan in the thickness direction A, the dye adsorption amount m ₁ per unit area in the outer portion 32 of the oxide semiconductor layer 30 is the inner portion of the oxide semiconductor layer 30. The dye adsorption amount m ₂ per unit area at 31 is larger. Here, the ratio of the dye adsorption amount m ₁ per unit area in the outer portion 32 to the dye adsorption amount m ₂ per unit area in the inner portion, that is, R ₁ represented by the following formula (1) is 1. Although it will not specifically limit if larger, it is preferable that it is 1.08-1.75. In this case, as compared with the case where R ₁ is out of the above range, the photoelectric conversion element 100 can achieve both more excellent power generation performance and more excellent durability. The value of R ₁ represented by the following formula (1) is more preferably 1.32 to 1.75.

R ₁ = m ₁ / m ₂ (1)
(In the above formula (1), m ₁ represents the amount of dye adsorbed per unit area (mol / m ² ) in the outer portion 32, and m ₂ represents the amount of dye adsorbed per unit area (mol / m in the inner portion 31). m ² )

When viewed in plan in the thickness direction of the oxide semiconductor layer 30, the oxide and the area S ₂ of the inner part 31 of the semiconductor layer 30, the ratio of the area S ₁ of the outer portion 32 of the oxide semiconductor layer 30, i.e. the following formula R ₂ represented by (2) is not particularly limited, but is preferably 0.37 to 5.51. In this case, the amount of dye adsorbed per unit volume in the outer portion 32, that is, the density of the dye in the outer portion 32, decreases compared to the case where the outer portion 32 does not have the protruding portion 32 a. Can be absorbed, and the photoelectric conversion characteristics are further improved. Further, as compared with the case where R ₂ is outside the above range, the photoelectric conversion element 100 can achieve both superior durability and superior power generation performance. R ₂ represented by the following formula (2) is more preferably 2.40 to 5.51. In this case, excellent durability can be obtained with a smaller amount of dye.

R ₂ = S ₂ / S ₁ (2)
(In the above formula (2), S ₁ represents the area (cm ² ) of the outer portion 32 in plan view in the thickness direction A of the oxide semiconductor layer 30, and S ₂ is the thickness of the oxide semiconductor layer 30. (The area (cm ² ) of the inner portion 31 when viewed in a plan view in the direction A is shown.)

The ratio between the thickness d ₂ of the inner portion 31 of the oxide semiconductor layer 30 and the thickness d ₁ of the outer portion 32 of the oxide semiconductor layer 30, that is, R ₃ represented by the following formula (3) is less than 1. If it is, it will not specifically limit, However, It is preferable that it is 0.63-0.95. In this case, in-plane variation of the short-circuit current density can be further reduced as compared with the case where R ₃ is out of the above range, and the change in the power generation characteristics of the photoelectric conversion element 100 due to uneven illuminance can be sufficiently suppressed. The R ₃ is more preferably 0.75 to 0.95. In this case, it is possible to achieve both better power generation performance and better durability.

R ₃ = d ₂ / d ₁ (3)
(In the above formula (3), d ₁ represents the thickness (μm) of the outer portion 32, and d ₂ represents the thickness (μm) of the inner portion 31.)

In addition, at a height H from the interface between the electrode substrate 10 and the oxide semiconductor layer 30, an annular region 32c obtained by cutting the protrusion 32a of the outer portion 32 of the oxide semiconductor layer 30 along a plane parallel to the interface. The area S ₁ ′ and the area S ₂ of the inner portion 31 of the oxide semiconductor layer 30 when viewed in plan in the thickness direction A of the oxide semiconductor layer 30, that is, expressed by the following formula (4) R ₄ is not particularly limited, but is preferably 0.17 to 2.69. In this case, in-plane variation of the short-circuit current density can be further reduced as compared with the case where R ₄ is out of the above range, and the change in the power generation characteristics of the photoelectric conversion element 100 due to uneven illuminance can be sufficiently suppressed.

R ₄ = S ′ ₁ / S ₂ (4)
(In the above formula (4), S ′ ₁ is a height H (μm) from the interface between the electrode substrate 10 and the oxide semiconductor layer 30, and the protruding portion 32 a of the outer portion 32 is cut along a plane parallel to the interface. The area (cm ² ) of the annular region 32c obtained in this way is represented, the height H (μm) satisfies the following formula (5), and S ₂ represents the area (cm ² ) of the inner part 31.
H = 1/2 (d ₁ + d ₂ ) (5)

<Counter substrate>
The counter substrate 20 includes a conductive substrate serving as a substrate and an electrode, and a conductive catalyst layer.

  The conductive substrate is made of a corrosion-resistant metal material such as titanium, nickel, platinum, molybdenum, tungsten, aluminum, and stainless steel. Further, the conductive substrate 21 may be formed of a laminate in which the substrate and the electrode are separated and a transparent conductive layer made of a conductive oxide such as ITO or FTO is formed as an electrode on the insulating transparent substrate 11 described above. Good.

  The thickness of the conductive substrate 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 4 mm.

  The catalyst layer is composed of platinum, a carbon-based material, a conductive polymer, or the like. Here, carbon nanotubes are suitably used as the carbon-based material. Note that the counter substrate 20 may not have a catalyst layer when the conductive substrate has a catalytic function (for example, when carbon or the like is contained).

  Further, as described above, the counter substrate 20 includes the annular portion 20a joined to the sealing portion 40, the proximity portion 20c closer to the oxide semiconductor layer 30 than the annular portion 20a, and the annular portion 20a and the proximity portion 20c. When the outer side portion 32 and the proximity portion 20c are viewed in the thickness direction A of the oxide semiconductor layer 20, the outer side portion 32 and the proximity portion 20c overlap each other. In this case, when the outer portion 32 and the proximity portion 20c are viewed in the thickness direction A of the oxide semiconductor layer 30, a higher short-circuit current value is obtained as compared with the case where the outer portion 32 and the proximity portion 20c do not overlap. Can be obtained.

<Sealing part>
Although the material which comprises the sealing part 40 is not specifically limited, As a material which comprises the sealing part 40, thermoplastic resins, such as modified polyolefin resin and a vinyl alcohol polymer, and ultraviolet curable resin, for example And other resins. Examples of the modified polyolefin resin include ionomer, maleic anhydride-modified polyolefin, ethylene-vinyl acetic anhydride copolymer, ethylene-methacrylic acid copolymer, and ethylene-vinyl alcohol copolymer. Especially, as a material which comprises the sealing part 40, maleic anhydride modified polyethylene is preferable. In this case, higher adhesive strength can be obtained for the electrode substrate 10 and the counter substrate 20.

<Electrolyte>
The electrolyte 50 includes a redox pair.

Examples of the redox pair include redox pairs such as iodide ion and polyiodide ion, bromide ion (bromine ion), and polybromide ion. The iodide ion and the 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 50 usually contains an organic solvent. As an organic solvent contained in the electrolyte 50, acetonitrile, methoxyacetonitrile, methoxypropionitrile, propionitrile, ethylene carbonate, propylene carbonate, diethyl carbonate, γ-butyrolactone, valeronitrile, pivalonitrile, or the like can be used.

  The electrolyte 50 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, 1-ethyl-3-methylimidazolium iodide, 1, 2 -Dimethyl-3-propylimidazolium iodide, 1-butyl-3-methylimidazolium iodide, or 1-methyl-3-propylimidazolium iodide is preferably used.

  The electrolyte 50 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 50. Examples of the additive include LiI, 4-t-butylpyridine, guanidinium thiocyanate, 1-methylbenzimidazole, 1-butylbenzimidazole and the like.

Furthermore, as the electrolyte 50, 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 above electrolyte may be used, and polyvinylidene fluoride may be used. Alternatively, an electrolyte gelled with an organic gelling agent such as a polyethylene oxide derivative or an amino acid derivative may be used.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the photoelectric conversion element 100 includes only one photoelectric conversion cell 60, but the photoelectric conversion element may include a plurality of photoelectric conversion cells 60. Here, the plurality of photoelectric conversion cells 60 may be connected in series or may be connected in parallel.

  Moreover, in the said embodiment, although the opposing board | substrate 20 is comprised by the cyclic | annular part 20a, the proximity part 20c, and the cyclic | annular connection part 20b which connects the cyclic | annular part 20a and the proximity part 20c, the opposing board | substrate 20 is cyclic | annular. The distance between the portion 20a and the electrode substrate 10 may be constituted by an inner portion where the distance between the annular portion 20a and the electrode substrate 10 is the same. That is, the counter substrate 20 may be flat.

  Further, in the above embodiment, the oxide semiconductor layer 30 is provided on the transparent conductive layer 12 of the electrode substrate 10 and the photoelectric conversion element has a structure in which light is received from the electrode substrate 10 side. In the case of using a laminate (transparent material) in which a transparent conductive layer made of a conductive oxide such as ITO or FTO is used as an electrode on the transparent substrate 11 as the conductive substrate 21 constituting the oxide semiconductor layer 30, Instead of the transparent substrate 11, an opaque material (for example, a metal substrate) may be used as the base material to be provided, and light reception may be performed from the counter substrate 20 side. Furthermore, when using the laminated body (transparent material) which formed the transparent conductive layer which consists of conductive oxides, such as ITO and FTO, as the electrode in the transparent substrate 11 as the conductive substrate 21 which comprises the opposing substrate 20, The photoelectric conversion element 100 has a structure in which light is received from both the electrode substrate 10 and the counter substrate 20.

Moreover, in the said embodiment, although the outer side part 32 of the oxide semiconductor layer 30 has the protrusion part 32a in the photoelectric conversion element 100, like the photoelectric conversion element 200 shown in FIG. The outer portion 232 of the semiconductor layer 230 may not have the protruding portion 32a. That is, the outer side part 232 may be comprised only by the main-body part 32b. However, in this case, the dye adsorption amount m ₁ per unit area in the outer portion 232 of the oxide semiconductor layer 30 needs to be larger than the dye adsorption amount m _{2 in} the inner portion 31 of the oxide semiconductor layer 30. is there.

  Furthermore, in the said embodiment, although the opposing board | substrate 20 is comprised with the electroconductive board | substrate 21 and the catalyst layer 22, the opposing board | substrate 20 may be comprised with an insulating substrate. As the insulating substrate, for example, a glass substrate or a resin film can be used. However, in this case, a counter electrode is provided on the oxide semiconductor layers 30 and 230. Here, the counter electrode can be the same as the counter substrate 20. Alternatively, the counter electrode may be composed of a single porous layer containing, for example, carbon. A porous insulating layer is provided between the oxide semiconductor layers 30 and 230 and the counter electrode. The porous insulating layer is mainly for impregnating the electrolyte 50 inside. As such a porous insulating layer, for example, an oxide fired body can be used. Note that the porous insulating layer may be provided between the electrode substrate 10 and the counter electrode so as to surround the oxide semiconductor layer 30.

  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, the laminated body formed by forming the transparent conductive layer which consists of 0.6 micrometer FTO on the transparent substrate which consists of glass 7cm x 7cmx2.2mm was prepared.

  Next, an oxide semiconductor layer having a thickness of 12 μm was formed on the transparent conductive layer. The oxide semiconductor layer is formed by printing a titanium oxide paste for forming a nanoparticle film containing titanium oxide particles (average particle size 21 nm) on a transparent conductive layer in a 50 mm × 50 mm square shape, and then heating at 460 ° C. for 90 minutes. It was formed by firing.

  Next, a reflective layer having a thickness of 3 μm was formed on the oxide semiconductor layer formed as described above. The reflective layer was formed by applying a titanium oxide paste for forming a reflective layer containing coarse titanium oxide particles (average particle size 400 nm) on the oxide semiconductor layer, followed by heating and baking at 460 ° C. for 90 minutes. . Thus, a structure was obtained.

  On the other hand, Z907 dye was dissolved in a mixed solvent in which t-butanol and acetonitrile were mixed at a volume ratio of 1: 1 to prepare a 0.5 mM first dye solution. Similarly, Z907 dye was dissolved in a mixed solvent in which t-butanol and acetonitrile were mixed at a volume ratio of 1: 1 to prepare a 0.2 mM second dye solution.

  And it immersed in the 0.5 mM 1st pigment | dye solution for 3 hours by using as an outer part the area | region from one side to 2 mm inside among four sides of the oxide semiconductor layer obtained as mentioned above. And this immersion was performed also to the area | region from the remaining each side to 2 mm inside among four sides of an oxide semiconductor layer. Thereafter, the entire oxide semiconductor layer was immersed in a 0.2 mM second dye solution overnight to adsorb the dye.

  Next, a rectangular opening was formed in a film of 5.6 cm × 5.6 cm × 100 μm thick to obtain an annular sealing portion having a thickness of 100 μm and a width of 2 mm. As a constituent material of the sealing portion, maleic anhydride-modified polyethylene (trade name “Binell 4164”, manufactured by DuPont) was used. And the cyclic | annular sealing part prepared as mentioned above was arrange | positioned so that an oxide semiconductor layer might be surrounded on a transparent conductive layer.

  Next, an electrolyte was dropped on the oxide semiconductor layer. At this time, as the electrolyte, a solution in which 3-methoxypropionitrile was used as a solvent and iodine was 0.002M and 1,3-dimethylpropylimidazolium iodide 0.6M was used.

  On the other hand, a counter substrate of 7 cm × 7 cm × 0.04 mm, which was obtained by sputtering platinum on a 0.04 mm thick titanium foil so as to have a thickness of 0.04 nm, was prepared.

  Then, this counter substrate was placed so as to face the oxide semiconductor layer, and the sealing portion was pressed while being heated at 190 ° C. to adhere the electrode substrate and the counter substrate. Thus, a photoelectric conversion element was obtained.

With respect to the photoelectric conversion element thus obtained, the adsorption amount m ₁ of the dye per unit area in the outer part of the oxide semiconductor layer and the adsorption amount m ₂ of the dye per unit area in the inner part of the oxide semiconductor layer are as follows: I asked for it.

That is, a structure having the same shape as the structure formed as described above is prepared, and after the dye is adsorbed to the oxide semiconductor layer as described above, the inner portion and the outer portion of the oxide semiconductor layer are separated. The electrode substrate is cut as described above, and the dye adsorbed on the outer oxide semiconductor layer is eluted with N, N-dimethylformamide containing tetrabutylammonium hydroxide, and the UV-Vis absorption spectrum for the solution By measuring the amount of dye adsorption M ₁ at the outer part, M ₁ is divided by the area S ₁ of the outer part when the oxide semiconductor layer is viewed in plan in the thickness direction of the oxide semiconductor layer. The adsorption amount m ₁ (= M ₁ / S ₁ ) of the dye per unit area in the outer part of the oxide semiconductor layer was determined. Similarly, the adsorption amount M ₂ of the dye in the inner part is obtained, and M ₂ is oxidized by dividing the oxide semiconductor layer by the area S ₂ of the inner part when the oxide semiconductor layer is viewed in the thickness direction of the oxide semiconductor layer. The adsorption amount m ₂ (= M ₂ / S ₂ ) of the dye per unit area in the inner part of the physical semiconductor layer was determined.

Furthermore, about the photoelectric conversion element, R ₁ represented by the following formula (1), R ₂ represented by the following formula (2), and R ₃ represented by the following formula (3) were determined. The results are shown in Table 1.

R ₁ = m ₁ / m ₂ (1)
(In the above formula (1), m ₁ represents the amount of dye adsorbed per unit area (mol / m ² ) in the outer part, and m ₂ represents the amount of dye adsorbed per unit area in the inner part (mol / m ^2). )

R ₂ = S ₂ / S ₁ (2)
(In the above formula (2), S ₁ represents the area (cm ² ) of the outer portion in plan view in the thickness direction of the oxide semiconductor layer, and S ₂ in plan view in the thickness direction of the oxide semiconductor layer. Represents the area (cm ² ) of the inner part in the case of

R ₃ = d ₂ / d ₁ (3)
(In the above formula (3), d ₁ represents the thickness (μm) of the outer portion, and d ₂ represents the thickness (μm) of the inner portion.)

(Examples 2 to 16)
By changing the concentration of the first dye solution, and the region of the four sides of the oxide semiconductor layer immersed in the first dye solution from one side to the inside, and the immersion time, the values of R ₁ and R ₂ are expressed. A photoelectric conversion element was produced in the same manner as in Example 1 except that the change was made as shown in FIG.

(Example 17)
When viewed in plan in the thickness direction of the oxide semiconductor layer, a square annular line 1 mm inside from the four sides of the oxide semiconductor layer, and a square annular line 2 mm inside from the four sides of the oxide semiconductor layer In the annular region between, the outer side thickness d ₁ (thickness d ₁ is the peak height of the annular region) on the main body having a thickness of 12 μm is the value shown in Table 2. A photoelectric conversion element was produced in the same manner as in Example 1 except that a protrusion was provided and R ₁ , R ₂ , R ₃ , R ₄ and H were as shown in Table 2.

In addition, about the photoelectric conversion element of Example 17 obtained as described above, R ₄ was calculated based on the following formula.

R ₄ = S ′ ₁ / S ₂ (4)
(In the above formula (4), S ′ ₁ is obtained by cutting the protruding portion of the outer portion along a plane parallel to the interface at a height H (μm) from the interface between the electrode substrate and the oxide semiconductor layer. The area (cm ² ) of the annular region is represented, the height H (μm) satisfies the following formula (5), and S ₂ represents the area (cm ² ) of the inner part.

H = 1/2 (d ₁ + d ₂ ) (5)

(Examples 18 to 21)
A photoelectric conversion element was produced in the same manner as in Example 17 except that the values of d ₁ , R ₁ , R ₃ , R ₄ and H were changed as shown in Table 2.

(Example 22)
When viewed in plan in the thickness direction of the oxide semiconductor layer, a quadrangular annular line 1 mm inside from the four sides of the oxide semiconductor layer, and a quadrangular annular line inside 4 mm from the four sides of the oxide semiconductor layer In the annular region between, a protrusion is provided on the main body having a thickness of 12 μm so that the thickness d ₁ of the outer portion is as shown in Table 2, and R ₁ , R ₂ , R ₃ , R ₄ and A photoelectric conversion element was produced in the same manner as in Example 17 except that the value of H was set as shown in Table 2.

(Examples 23 to 26)
A photoelectric conversion element was produced in the same manner as in Example 22 except that the values of d ₁ , R ₁ , R ₃ , R ₄ and H were changed as shown in Table 2.

(Example 27)
When viewed in plan in the thickness direction of the oxide semiconductor layer, in an annular region between the annular line 1 mm inside from the four sides of the oxide semiconductor layer and the annular line inside 8 mm from the four sides of the oxide semiconductor layer A protrusion is provided on the main body having a thickness of 12 μm so that the thickness d ₁ of the outer portion is as shown in Table 2, and the values of R ₁ , R ₂ , R ₃ , R ₄ and H are represented. A photoelectric conversion element was produced in the same manner as in Example 17 except that the procedure was as shown in 2.

(Examples 28 to 31)
A photoelectric conversion element was produced in the same manner as in Example 27 except that the values of d ₁ , R ₁ , R ₃ , R ₄ and H were changed as shown in Table 2.

(Example 32)
When viewed in plan in the thickness direction of the oxide semiconductor layer, a quadrangular annular line 1 mm inside from the four sides of the oxide semiconductor layer, and a quadrangular annular line 16 mm inside from the four sides of the oxide semiconductor layer, In the annular region between, a protrusion is provided on the main body having a thickness of 12 μm so that the thickness d ₁ of the outer portion is as shown in Table 2, and R ₁ , R ₂ , R ₃ , R ₄ A photoelectric conversion element was produced in the same manner as in Example 17 except that the values of H and H were as shown in Table 2.

(Examples 33 to 36)
A photoelectric conversion element was produced in the same manner as in Example 32 except that the values of d ₁ , R ₁ , R ₃ , R ₄ and H were changed as shown in Table 2.

(Comparative Example 1)
A photoelectric conversion element was produced in the same manner as in Example 1 except that the oxide semiconductor layer was not immersed in the 0.5 mM first dye solution when adsorbing the dye to the oxide semiconductor layer.

<Power generation performance>
With respect to the photoelectric conversion elements of Examples 1 to 36 and Comparative Example 1 obtained as described above, an IV curve was measured in a state where 200 lux white light was irradiated immediately after the production, and the maximum calculated from the IV curve. The output operating power Pm ₀ (μW) was calculated as “output 1”. The light source, illuminance meter, and power source used for measuring the IV curve are as follows.

Light source: White LED (product name “LEL-SL5N-F”, manufactured by Toshiba Lighting & Technology Corp.)
Illuminance meter: Product name “Digital Illuminance Meter 51013”, Yokogawa Meter & Instruments Power Supply: Voltage / Current Generator (Product name “R6246I”, ADVANTEST)

  By dividing the output 1 in Examples 1 to 36 and Comparative Example 1 by the output 1 of Comparative Example 1, the ratio of the initial outputs of Examples 1 to 36 and Comparative Example 1 to the initial output of Comparative Example 1 was calculated. The results are shown in Tables 1 and 2.

<Durability>
After placing the photoelectric conversion elements of Examples 1 to 78 and Comparative Example 1 at room temperature with a relative humidity of 60% for 1000 hours, the photoelectric conversion elements were again irradiated with 200 lux of the above-mentioned white light and the IV curve was measured. The maximum output operating power PW (μW) calculated from the IV curve was calculated as “output 2”. And the output maintenance factor was computed based on the following formula, and also the relative value of the output maintenance factor when the output maintenance factor of comparative example 1 was set to 1.00 was calculated. The results are shown in Tables 1 and 2.

Output maintenance rate = Output 2 / Output 1

<Short-circuit current density in-plane variation>
Using a solar cell conversion efficiency distribution measuring instrument MAP50 (manufactured by Lasertec), the distribution of short-circuit current density per 1 mm ² in the power generation surface of the photoelectric conversion element placed at room temperature with a relative humidity of 60% for 1000 hours is measured. Then, the maximum value and the minimum value of the short circuit current density in the power generation plane were calculated, and the short circuit current density in-plane variation was calculated based on the following formula.

Short-circuit current density in-plane variation = (maximum value of short-circuit current density-minimum value of short-circuit current density) / [(maximum value of short-circuit current density + minimum value of short-circuit current density) / 2]

When R ₃ is 0.63 to 0.95 and R ₄ is 0.17 to 2.69, the short-circuit current density in-plane variation can be suppressed to 8.0% or less.

  As shown in Tables 1 and 2, it was found that the photoelectric conversion elements of Examples 1 to 36 had superior durability compared to the photoelectric conversion element of Comparative Example 1.

  Therefore, according to the photoelectric conversion element of this invention, it was confirmed that it has the outstanding durability.

DESCRIPTION OF SYMBOLS 10 ... Electrode substrate 20 ... Counter substrate 20a ... Annular part 20b ... Connection part 20c ... Proximity part 30,230 ... Oxide semiconductor layer 31 ... Inner part 32,232 ... Outer part 32a ... Projection part 32b ... Main part 40 ... Sealing Part 50 ... Electrolyte 60, 260 ... Photoelectric conversion cell 100, 200 ... Photoelectric conversion element d ₁ ... Thickness of outer part d ₂ ... Thickness of inner part

Claims (6)

Comprising at least one photoelectric conversion cell;
The photoelectric conversion cell is
An electrode substrate;
A counter substrate facing the electrode substrate;
An oxide semiconductor layer provided on the electrode substrate;
A dye adsorbed on the oxide semiconductor layer;
An annular sealing portion that joins the electrode substrate and the counter substrate and surrounds the oxide semiconductor layer;
An electrolyte that fills a cell space formed by the electrode substrate, the counter substrate, and the sealing portion;
When the oxide semiconductor layer is viewed in plan in the thickness direction of the oxide semiconductor layer,
The inner part,
An annular outer portion surrounding the inner portion;
When the oxide semiconductor layer is viewed in plan in the thickness direction, the amount of the dye adsorbed per unit area in the outer portion is larger than the amount of the dye adsorbed per unit area in the inner portion. Conversion element. The photoelectric conversion element according to claim 1, wherein R ₁ represented by the following formula (1) is 1.08 to 1.75.
R ₁ = m ₁ / m ₂ (1)
(In the formula (1), m ₁ represents the adsorption amount (mol / m ² ) of the dye per unit area in the outer portion, and m ₂ represents the adsorption amount of the dye per unit area in the inner portion ( mol / m ² ).) The outer portion is
A main body provided on the electrode substrate and having the same thickness as the inner part;
A projecting portion projecting from the main body portion toward the counter substrate;
The photoelectric conversion element according to claim 2, wherein R ₂ represented by the following formula (2) is 0.37 to 5.51.
R ₂ = S ₂ / S ₁ (2)
(In the above formula (2), S ₁ represents the area (cm ² ) of the outer portion in plan view in the thickness direction of the oxide semiconductor layer, and S ₂ represents the thickness direction of the oxide semiconductor layer. (Indicates the area (cm ² ) of the inner part in plan view.) The photoelectric conversion element according to claim 3, wherein R ₃ represented by the following formula (3) is 0.63 to 0.95.
R ₃ = d ₂ / d ₁ (3)
(In the above formula (3), d ₁ represents the thickness (μm) of the outer portion, and d ₂ represents the thickness (μm) of the inner portion.) The photoelectric conversion element according to claim 3 or 4, wherein R ₄ represented by the following formula (4) is 0.17 to 2.69.
R ₄ = S ′ ₁ / S ₂ (4)
(In the above formula (4), S ′ ₁ is a height H (μm) from the interface between the electrode substrate and the oxide semiconductor layer, and the protruding portion of the outer portion is cut along a plane parallel to the interface. Represents the area (cm ² ) of the annular region obtained as described above, the height H (μm) satisfies the following formula (5), and S ₂ is a plan view in the thickness direction of the oxide semiconductor layer. (Inner area (cm ² ) is indicated.)
H = 1/2 (d ₁ + d ₂ ) (5)
(In the above formula (5), d ₂ represents the thickness (μm) of the inner portion in plan view in the thickness direction of the oxide semiconductor layer.) The counter substrate is
An annular portion joined to the sealing portion;
A proximity portion closer to the oxide semiconductor layer than the annular portion;
An annular connecting portion that connects the annular portion and the proximity portion;
The photoelectric device according to any one of claims 1 to 5, wherein the outer portion and the proximity portion overlap when the outer portion and the proximity portion are viewed in a thickness direction of the oxide semiconductor layer. Conversion element.

Images