JP2017022324A - Photoelectric conversion element - Google Patents

Abstract

Provided is a photoelectric conversion element that can improve photoelectric conversion characteristics and has excellent durability. The photoelectric conversion cell includes at least one photoelectric conversion cell, and the photoelectric conversion cell includes a conductive substrate, a semiconductor layer provided on the conductive substrate, and a transparent counter substrate disposed so as to face the conductive substrate. And a sealing portion provided so as to connect the conductive substrate and the counter substrate, and an electrolyte disposed between the conductive substrate and the counter substrate, and the counter substrate with respect to at least one photoelectric conversion cell. A photoelectric conversion element to which light is incident from, wherein a conductive substrate is provided with a metal substrate and a metal oxide that constitutes the metal substrate and is provided on the metal substrate so as to be in contact with the semiconductor layer. The photoelectric conversion element which has 1 metal oxide layer and the thickness of a 1st metal oxide layer is 100-500 nm. [Selection] Figure 1

Description

  The present invention relates to a photoelectric conversion element.

  The dye-sensitized solar cell was developed by Gretzell et al. In Switzerland, and is a next-generation photoelectric conversion element that has attracted attention because it has advantages such as high photoelectric conversion efficiency and low manufacturing cost.

  A photoelectric conversion element using such a dye generally includes at least one photoelectric conversion cell, and the photoelectric conversion cell faces the conductive substrate, the semiconductor layer provided on the conductive substrate, and the conductive substrate. And a transparent counter substrate. As such a photoelectric conversion element, a so-called back-illuminated photoelectric conversion element in which light is incident not from a conductive substrate provided with a semiconductor layer but from a transparent counter substrate facing the semiconductor layer is known. In such a back-illuminated photoelectric conversion element, light is incident from the counter substrate, so that the conductive substrate does not need to be transparent.

  For example, Patent Document 1 below discloses the use of a substrate containing titanium as the conductive substrate.

JP 2010-198834 A (FIG. 3)

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

  This invention is made | formed in view of the said situation, and it aims at providing the photoelectric conversion element which can improve a photoelectric conversion characteristic and has outstanding durability.

  This inventor examined the cause which cannot solve the said subject even if it uses the board | substrate containing titanium as a conductive substrate. As a result, the present inventor has noticed the following. That is, the present inventors have found that the range of the thickness of the titanium oxide layer formed on the substrate containing titanium is extremely important for solving the above-described problems, and have completed the present invention.

  That is, the present invention includes at least one photoelectric conversion cell, and the photoelectric conversion cell is disposed so as to face a conductive substrate, a semiconductor layer provided on the conductive substrate, and the conductive substrate. An at least one counter substrate, a sealing portion provided to connect the conductive substrate and the counter substrate, and an electrolyte disposed between the conductive substrate and the counter substrate. A photoelectric conversion element in which light is incident on one photoelectric conversion cell from the counter substrate, wherein the conductive substrate is provided in contact with the metal layer and the semiconductor layer on the metal substrate, It is a photoelectric conversion element which has a 1st metal oxide layer comprised with the metal oxide which comprises a metal substrate, and the thickness of the said 1st metal oxide layer is 100-500 nm.

  According to this photoelectric conversion element, since the first metal oxide layer is composed of a metal oxide constituting the metal substrate, the first metal oxide layer is firmly fixed to the metal substrate. The first metal oxide layer is provided on the metal substrate so as to be in contact with the semiconductor layer. For this reason, the metal substrate and the semiconductor layer are firmly fixed via the first metal oxide layer. In particular, when the thickness of the first metal oxide layer is 100 nm or more, the metal substrate and the semiconductor layer are more firmly fixed via the first metal oxide layer than when the thickness is less than 100 nm. . For this reason, peeling of the semiconductor layer from the conductive substrate can be sufficiently suppressed, and the photoelectric conversion element can have excellent durability. In addition, since the thickness of the first metal oxide layer is 500 nm or less, the resistance between the conductive substrate and the semiconductor layer is reduced as compared with the case where the thickness of the first metal oxide layer exceeds 500 nm. Therefore, the photoelectric conversion characteristics of the photoelectric conversion element can be improved.

  In the said photoelectric conversion element, it is preferable that the said sealing part contains resin and is provided on the said 1st metal oxide layer.

  In this case, since the sealing portion includes a resin and is provided on the first metal oxide layer, the sealing portion and the conductive substrate can be firmly fixed. For this reason, it can fully suppress that an electrolyte leaks from between a 1st metal oxide layer and a sealing part. Therefore, the photoelectric conversion element can have more excellent durability.

  In the photoelectric conversion element, the conductive substrate is provided on the opposite side of the metal substrate from the semiconductor layer, and further includes a second metal oxide layer formed of a metal oxide constituting the metal substrate. It is preferable that the photoelectric conversion element further includes a connection terminal provided on the second metal oxide layer.

  In this case, the connection terminal can be firmly fixed to the second metal oxide layer. For this reason, it can suppress that a connection terminal peels from a metal substrate, and it becomes possible for a photoelectric conversion element to have the outstanding durability.

  The photoelectric conversion element is particularly useful when the conductive substrate and the counter substrate are flexible.

  That is, when the conductive substrate and the counter substrate have flexibility and the thickness of the first metal oxide layer is less than 100 to 500 nm in the conductive substrate, the entire photoelectric conversion element is bent. In particular, the metal substrate and the semiconductor layer of the conductive substrate are easily peeled off. In that respect, since the thickness of the first metal oxide layer is in the range of 100 to 500 nm in the conductive substrate, the metal substrate and the semiconductor layer of the conductive substrate are firmly connected via the first metal oxide layer. It is fixed and peeling between the metal substrate of the conductive substrate and the semiconductor layer is sufficiently suppressed.

In the present invention, the conductive substrate or the counter substrate (hereinafter referred to as “substrate” in this paragraph) “has flexibility” means that the long side of a 50 mm × 200 mm substrate in an environment of 20 ° C. Both edges (5 mm in width) are fixed horizontally with a tension of 1 N, and the maximum deformation rate of the substrate when the load of 20 g is applied to the center of the substrate exceeds 20%. Here, the maximum deformation rate is a value calculated based on the following equation.
Maximum deformation rate (%) = 100 × (maximum displacement / substrate thickness)
Therefore, for example, when a substrate having a thickness of 0.04 mm is bent by applying a load as described above and the maximum deformation amount is 0.01 mm, the maximum deformation rate is 25%, and this substrate has flexibility. Will have.

  ADVANTAGE OF THE INVENTION According to this invention, a photoelectric conversion element which can improve a photoelectric conversion characteristic and has outstanding durability is provided.

It is sectional drawing which shows one Embodiment of the photoelectric conversion element of this invention. FIG. 2 is a partial cross-sectional end view showing the vicinity of a boundary between a semiconductor layer and a metal substrate in the photoelectric conversion element of FIG. 1. It is a figure for demonstrating ratio which shows the degree of curvature of the electroconductive board | substrate of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings, the same or equivalent components are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a cross-sectional view showing an embodiment of a photoelectric conversion element according to the present invention, and FIG. 2 is a partially cut end view showing the vicinity of the boundary between a semiconductor layer and a metal substrate in the photoelectric conversion element of FIG.

  As shown in FIG. 1, the photoelectric conversion element 100 includes one photoelectric conversion cell 50. The photoelectric conversion cell 50 includes a conductive substrate 15 and a working electrode 10 having a semiconductor layer 13 provided on the conductive substrate 15, and a transparent counter substrate 21 disposed so as to face the conductive substrate 15 of the working electrode 10. The transparent counter electrode 20 having the above, the dye supported on the semiconductor layer 13 of the working electrode 10, the working electrode 10 and the counter electrode 20 are connected, and the conductive substrate 15 and the counter substrate 21 are connected. An annular sealing portion 30 containing a resin and an electrolyte 40 disposed between the working electrode 10 and the counter electrode 20 are provided. In the photoelectric conversion cell 100, light is incident from the counter electrode 20. That is, the photoelectric conversion element 100 is a so-called back-illuminated photoelectric conversion element.

  The counter electrode 20 includes a conductive transparent counter substrate 21 and a conductive catalyst layer 22 that is provided on the working electrode 10 side of the counter substrate 21 and promotes a reduction reaction on the surface of the counter substrate 21. . Furthermore, in the present embodiment, the counter substrate 21 has flexibility.

  The working electrode 10 has a conductive substrate 15 and a semiconductor layer 13 provided on the conductive substrate 15. The conductive substrate 15 is provided so as to be in contact with the semiconductor layer 13 on the metal substrate 11, and the first metal oxide layer 16 b made of a metal oxide constituting the metal substrate 11, The metal substrate 11 includes a second metal oxide layer 16 a that is provided on the opposite side of the semiconductor layer 13 and is made of a metal oxide that forms the metal substrate 11. Here, the first metal oxide layer 16b is in close contact with the semiconductor layer 13 (see FIG. 2). The thicknesses of the first metal oxide layer 16b and the second metal oxide layer 16a are 100 to 500 nm, respectively. Moreover, the sealing part 30 containing resin is provided on the 1st metal oxide layer 16b. Furthermore, in this embodiment, the conductive substrate 15 has flexibility.

  Further, a connection terminal 17 is provided on the second metal oxide layer 16a.

  According to the photoelectric conversion element 100 described above, since the first metal oxide layer 16b is composed of a metal oxide constituting the metal substrate 11, the first metal oxide layer 16b is firmly attached to the metal substrate 11. Fixed. The first metal oxide layer 16 b is provided on the metal substrate 11 so as to be in contact with the semiconductor layer 13. For this reason, the metal substrate 11 and the semiconductor layer 13 are firmly fixed via the first metal oxide layer 16b. In particular, since the thickness of the first metal oxide layer 16b is 100 nm or more, the metal substrate 11 and the semiconductor layer 13 are more robust via the first metal oxide layer 16b than when the thickness is less than 100 nm. Fixed to. For this reason, peeling of the semiconductor layer 13 from the working electrode 10 can be sufficiently suppressed, and the photoelectric conversion element 100 can have excellent durability. In addition, since the thickness of the first metal oxide layer 16b is 500 nm or less, the thickness of the first metal oxide layer 16b is more than 500 nm between the conductive substrate 15 and the semiconductor layer 13. Therefore, the photoelectric conversion characteristics of the photoelectric conversion element 100 can be improved.

  Moreover, in the photoelectric conversion element 100, since the sealing part 30 contains resin and is provided on the first metal oxide layer 16b, the sealing part 30 and the conductive substrate 15 can be firmly fixed. . For this reason, it can fully suppress that the electrolyte 40 leaks from between the 1st metal oxide layer 16b and the sealing part 30. FIG. Therefore, the photoelectric conversion element 100 can have more excellent durability.

  Further, in the photoelectric conversion element 100, the connection terminal 17 is provided on the second metal oxide layer 16a. For this reason, the connection terminal 17 and the electric substrate 15 can be firmly fixed. For this reason, it can suppress that the connection terminal 17 peels from the 2nd metal oxide layer 16a, and it becomes possible for the photoelectric conversion element 100 to have the outstanding durability.

  Further, in the photoelectric conversion element 100, when the conductive substrate 15 and the counter substrate 21 have flexibility and the thickness of the first metal oxide layer 16b in the conductive substrate 15 is less than the range of 100 to 500 nm. When the whole photoelectric conversion element 100 is bent, the metal substrate 11 and the semiconductor layer 13 of the conductive substrate 15 are particularly easily peeled off. In that respect, since the thickness of the first metal oxide layer 16b in the conductive substrate 15 is in the range of 100 to 500 nm, the metal substrate 11 and the semiconductor layer 13 of the conductive substrate 15 are the first metal oxide layer. The metal substrate of the conductive substrate 15 and the semiconductor layer are sufficiently prevented from being peeled off.

  Next, the working electrode 10, the dye, the counter electrode 20, the sealing portion 30, the electrolyte 40, and the connection terminal 17 will be described in detail.

<Working electrode>
As described above, the working electrode 10 includes the conductive substrate 15 and the semiconductor layer 13 provided on the conductive substrate 15. As shown in FIG. 1, for example, the conductive substrate 15 includes a metal substrate 11, a first metal oxide layer 16 b made of a metal oxide that forms the metal substrate 11, and a metal that forms the metal substrate 11. A second metal oxide layer 16a made of an oxide.

(Metal substrate)
As the metal constituting the metal substrate 11, a metal capable of forming a passive state, such as titanium or tungsten, is used.

  The thickness of the metal substrate 11 is not particularly limited, but is usually 500 μm or less, preferably 20 to 200 μm.

  The metal substrate 11 preferably has a number of concave surfaces on its surface.

(First metal oxide layer)
The first metal oxide layer 16 b is composed of a metal oxide constituting the metal substrate 11. Examples of such metal oxides include TiO ₂ and WO ₃ .

  Although the thickness of the 1st metal oxide layer 16b should just be 100-500 nm, it is preferable that it is 100-300 nm. In this case, compared with the case where the thickness of the 1st metal oxide layer 16b remove | deviates from the range of 100-300 nm, a photoelectric conversion characteristic can be improved more and it becomes possible to have more outstanding durability.

  It is preferable that the 1st metal oxide layer 16b has many concave surfaces on the surface. In this case, since the contact area between the sealing portion 30 and the first metal oxide layer 16b is increased, the sealing portion 30 and the conductive substrate 15 can be more firmly fixed. For this reason, it can suppress more fully that the electrolyte 40 leaks from between the 1st metal oxide layer 16b and the sealing part 30. FIG. Therefore, the photoelectric conversion element 100 can have more excellent durability.

  It is preferable that a smaller concave surface is formed on each of the multiple concave surfaces. In this case, since the contact area between the sealing part 30 and the first metal oxide layer 16b is further increased, the photoelectric conversion element 100 can have more excellent durability.

(Second metal oxide layer)
The second metal oxide layer 16a is made of the same metal oxide as the first metal oxide layer 16b.

  Although the thickness of the 2nd metal oxide layer 16a should just be 100-500 nm, it is preferable that it is 100-300 nm. In this case, compared with the case where the thickness of the 2nd metal oxide layer 16a remove | deviates from the range of 100-300 nm, a photoelectric conversion characteristic can be improved more and it can have more outstanding durability.

  It is preferable that the 2nd metal oxide layer 16a has many concave surfaces on the surface. In this case, since the contact area between the connection terminal 17 and the second metal oxide layer 16a becomes larger, the connection terminal 17 and the conductive substrate 15 can be more firmly fixed. For this reason, it can fully suppress that the connection terminal 17 peels from the electroconductive board | substrate 15. FIG. Therefore, the photoelectric conversion element 100 can have more excellent durability.

  It is preferable that a smaller concave surface is formed on each of the multiple concave surfaces. In this case, since the contact area between the second metal oxide layer 16a and the connection terminal 17 is further increased, the photoelectric conversion element 100 can have more excellent durability.

Is not particularly limited sheet resistance of the conductive substrate 15, 1 × ¹⁰ -5 preferably to 1 × 10 is ^{2 Ω / □, 1 × 10} -5 ~1 × 10 -1 Ω / □ It is more preferable that

  On the side surface of the conductive substrate 15, the length of a line segment connecting points at both ends of the second long side with respect to the length of the second long side opposite to the first long side corresponding to the surface on which the semiconductor layer 13 is provided The ratio is not particularly limited, but is preferably 0.5 to 1. In this case, the photoelectric conversion element 100 can have more excellent durability. Here, the ratio will be described with reference to FIG.

  FIG. 3A is a diagram illustrating a side surface of the conductive substrate 15 in the working electrode 10 of the photoelectric conversion element 100, and illustrates a state in which the conductive substrate 15 is not curved. Here, the side surface of the conductive substrate 15 is the side surface having the largest area among all the side surfaces of the conductive substrate 15, the surface of the conductive substrate 15 on which the semiconductor layer 13 is provided, and the surface thereof. The surface that connects the opposite surface. In FIG. 3A, AB is the first long side 15a corresponding to the surface on which the semiconductor layer 13 is provided, and A'B 'is the second long side opposite to the first long side 15a. 15b. On the other hand, a line segment 15c connecting the points A 'and B' at both ends of the second long side 15b coincides with the second long side 15b. For this reason, when the conductive substrate 15 is not curved, L1 = L, so the ratio (L1 / L) of the length L1 of the line segment 15c to the length L of the second long side 15b is 1. .

  On the other hand, FIG. 3B is a diagram showing a side surface of the conductive substrate 15 in the working electrode 10 of the photoelectric conversion element 100, and shows a state where the conductive substrate 15 is curved. In FIG. 3B, a line segment 15c connecting the points A 'and B' at both ends of the second long side 15b does not coincide with the second long side 15b. For this reason, in the state where the conductive substrate 15 is curved, L1 <L, so the ratio (L1 / L) of the length L1 of the line segment 15c to the length L of the second long side 15b is less than 1. Value. In particular, when L1 = 0, L1 / L becomes zero.

(Semiconductor layer)
The semiconductor layer 13 is composed of semiconductor particles 13a (see FIG. 2). Examples of the semiconductor particles 3a 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 ) And oxide semiconductor particles such as holmium oxide (Ho ₂ O ₃ ), bismuth oxide (Bi ₂ O ₃ ), cerium oxide (CeO ₂ ), and aluminum oxide (Al ₂ O ₃ ). These may be used alone or in combination of two or more thereof.

<Dye>
Examples of the dye include a ruthenium complex having a ligand containing a bipyridine structure, a terpyridine structure, etc., a photosensitizing dye such as an organic dye such as porphyrin, eosin, rhodamine, merocyanine, and an organic-type such as a lead halide perovskite. 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.

  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.

<Counter electrode>
As described above, the counter electrode 20 includes the transparent counter substrate 21 and the conductive transparent catalyst layer 22.

(Opposite substrate)
The counter substrate 21 is composed of a transparent substrate having a transparent conductive layer, for example.

  The transparent substrate should just be comprised with the transparent material. Examples of such transparent materials include borosilicate glass, soda lime glass, white plate glass, and quartz glass, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), and polyethersulfone (PES). ) And the like. The thickness of the counter substrate 21 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.

Examples of the material constituting the transparent conductive layer include transparent conductive metal oxides such as tin-added indium oxide (ITO), tin oxide (SnO ₂ ), and fluorine-added tin oxide (FTO). Especially, since a transparent conductive layer has high heat resistance and chemical resistance, it is preferable to be comprised by FTO. The thickness of the transparent conductive layer may be in the range of 0.01 to 2 μm, for example.

(Catalyst layer)
The catalyst layer 22 is composed of platinum, a carbon-based material, a conductive polymer, or the like. Here, examples of the carbon-based material include carbon black, ketjen black, and carbon nanotube, and among these, carbon nanotube is particularly preferably used.

<Sealing part>
As a material constituting the sealing portion 30, for example, an inorganic insulating material such as a non-lead transparent low melting point glass frit, an ionomer, an ethylene-vinyl acetic anhydride copolymer, an ethylene-methacrylic acid copolymer, ethylene -Modified polyolefin resin containing vinyl alcohol copolymer etc., ultraviolet curable resin, and resin such as vinyl alcohol polymer.

<Electrolyte>
The electrolyte 40 contains, for example, a redox couple (I ⁻ / I ₃ ⁻ etc.) formed by mixing iodine and an iodide salt, and an organic solvent. As an organic solvent, acetonitrile, methoxyacetonitrile, methoxypropionitrile, propionitrile, ethylene carbonate, propylene carbonate, diethyl carbonate, γ-butyrolactone, valeronitrile, pivalonitrile, glutaronitrile, methacrylonitrile, isobutyronitrile, Phenylacetonitrile, acrylonitrile, succinonitrile, oxalonitrile, pentanitrile, adiponitrile and the like can be used. Examples of the redox pair include I ⁻ / I ₃ ^— and redox pairs such as bromine / bromide ions, zinc complexes, iron complexes, and cobalt complexes. The electrolyte 40 may use an ionic liquid instead of the organic solvent. As the ionic liquid, for example, known iodine salts such as pyridinium salts, imidazolium salts, triazolium salts, and the like are used. Examples of such iodine salts include 1-hexyl-3-methylimidazolium iodide, 1-ethyl-3-propylimidazolium iodide, dimethylimidazolium iodide, ethylmethylimidazolium iodide, and dimethylpropylimidazole. Lithium iodide, butylmethyl imidazolium iodide, or methylpropyl imidazolium iodide is preferably used.

  In addition, the electrolyte 40 may use a mixture of the ionic liquid and the organic solvent instead of the organic solvent.

  An additive can be added to the electrolyte 40. Examples of the additive include benzimidazoles such as 1-methylbenzimidazole (NMB) and 1-butylbenzimidazole (NBB), LiI, I2, 4-t-butylpyridine, and guanidinium thiocyanate. Among them, benzimidazole is preferable as an additive.

Further, as the electrolyte 40, a nano-composite gel electrolyte, which is a pseudo-solid electrolyte formed by kneading nanoparticles such as SiO ₂ , TiO ₂ , carbon nanotubes, etc. into the 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 electrolyte 40 preferably includes an oxidation-reduction pair (I ⁻ / I ₃ ⁻ ) formed by mixing iodine and an iodide salt, and the concentration of I ₃ ⁻ is 0.006 mol / liter or less. . In this case, since the concentration of I ₃ ⁻ that carries electrons is low, a decrease in the amount of light incident on the semiconductor layer 13 from the counter substrate 21 can be sufficiently suppressed. For this reason, the photoelectric conversion characteristics of the photoelectric conversion element 100 can be further improved. In particular, the concentration of I ₃ ⁻ 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 incident side of the counter substrate 21, the color of the electrolyte 40 can be made inconspicuous.

<Connection terminal>
The connection terminal 17 contains a metal. Examples of the metal include silver and gold. The connection terminal 17 preferably has a lower sheet resistance than the conductive substrate 15. In this case, the photoelectric conversion characteristics of the photoelectric conversion element 100 can be further improved.

  Next, a method for manufacturing the photoelectric conversion element 100 will be described.

<Working electrode formation process>
First, the working electrode 10 is prepared as follows.

  First, the metal substrate 11 is prepared.

(Semiconductor layer forming process)
Next, a semiconductor layer forming paste for forming the semiconductor layer 13 is applied on the metal substrate 11 by printing or the like. The semiconductor layer forming paste contains semiconductor particles, a resin such as polyethylene glycol and ethyl cellulose, and a solvent such as terpineol.

  Examples of the method for printing the semiconductor layer forming paste include a screen printing method, a doctor blade method, and a bar coating method.

  Next, the semiconductor layer forming paste is collectively baked to form the semiconductor layer 13 on the metal substrate 11. At the same time, the first metal oxide layer 16b is formed on the semiconductor substrate 13 side of the metal substrate 11, and the second metal oxide layer 16a is formed on the opposite side of the metal substrate 11 from the semiconductor layer 13. At this time, the first metal oxide layer 16 b is formed so as to be in contact with the semiconductor layer 13. In order to set the thickness of the first metal oxide layer 16b to 100 to 500 nm, for example, the firing temperature is preferably 300 to 600 ° C., and the firing time is preferably 0.5 to 2 hours. Further, in order to set the thickness of the first metal oxide layer 16b to 100 to 500 nm, pre-annealing is performed on the metal substrate 11 before applying the semiconductor layer forming paste on the metal substrate 11 as necessary. Processing may be performed. Moreover, after performing a pre-annealing process, you may perform an acid process. Here, the pre-annealing treatment tends to increase the thickness of the first metal oxide layer 16b by increasing the annealing temperature. On the other hand, the acid treatment tends to reduce the thickness of the first metal oxide layer 16b. For this reason, the metal substrate 11 is not subjected to any treatment in advance, only pre-annealed in advance, or subjected to acid treatment after pre-annealing in advance, thereby increasing the thickness of the first metal oxide layer 16b. It is possible to control the thickness to a desired value.

  Note that the temperature of the pre-annealing process may normally be 300 to 600 ° C., and the time may be 30 to 90 minutes. Examples of the acid used for the acid treatment include hydrogen fluoride (HF) and hydrochloric acid (HCl). The acid treatment time may be 60 minutes or less.

  Thus, the working electrode 10 is obtained.

<Connection terminal fixing process>
Next, a connection terminal forming paste for forming the connection terminals 17 is printed on the second metal oxide layer 16 a of the working electrode 10. The connection terminal forming paste is made of metal, polyester resin, acrylic resin, phenol resin, vinyl chloride vinyl acetate copolymer resin, urethane resin, epoxy resin, cellulose resin, and the like, and toluene, acetone, 1-propanol, etc. Contains solvent.

  Examples of the method for printing the connection terminal forming paste include a screen printing method, a doctor blade method, and a bar coating method.

  Next, the connection terminal 17 is formed on the second metal oxide layer 16a by drying and curing the connection terminal forming paste.

<Dye supporting step>
Next, the pigment is supported on the semiconductor layer 13 of the working electrode 10. For this purpose, for example, the working electrode 10 is immersed in a solution containing a dye, the dye is adsorbed to the semiconductor layer 13, and then the excess dye is washed away with the solvent component of the solution and dried. A dye may be adsorbed on the semiconductor layer 13.

<Counterelectrode preparation process>
On the other hand, the counter electrode 20 is prepared as follows.

  First, a transparent counter substrate 21 is prepared. Then, the catalyst layer 22 is formed on the counter substrate 21. Examples of the method for forming the catalyst layer 22 include a sputtering method, a screen printing method, and a vapor deposition method.

<Sealing part fixing process>
Next, for example, an annular sheet made of a thermoplastic resin is prepared. And this sheet | seat is mounted on the working electrode 10 which has the semiconductor layer 13 which carry | supported the pigment | dye, and is heat-melted. At this time, the semiconductor layer 13 is arranged inside the annular sheet. In this way, the annular resin sheet is fixed to the surface of the working electrode 10.

<Electrolyte placement process>
Next, the electrolyte 40 is prepared. The electrolyte 40 is disposed inside the annular resin sheet fixed on the working electrode 10. The electrolyte 40 can be disposed by, for example, a dropping method.

<Sealing process>
After the electrolyte 40 is disposed on the working electrode 10, the counter substrate 21 of the counter electrode 20 is superimposed on the conductive substrate 15 of the working electrode 10 so that the electrolyte 40 is sandwiched between the conductive substrate 15 and the annular shape. By heating and melting the resin sheet, the conductive substrate 15 of the working electrode 10 and the counter substrate 21 of the counter electrode 20 are bonded. In this way, the photoelectric conversion element 100 having the photoelectric conversion cell 50 having the sealing portion 30 between the working electrode 10 and the counter electrode 20 is obtained, and the manufacture of the photoelectric conversion element 100 is completed.

  The present invention is not limited to the above embodiment. For example, in the said embodiment, although the photoelectric conversion element is comprised by the one photoelectric conversion cell 50, the photoelectric conversion element of this invention may be comprised by the some photoelectric conversion cell 50. FIG.

  In the above embodiment, the connection terminal 17 is provided on the second metal oxide layer 16a. However, the connection terminal 17 may not be provided on the second metal oxide layer 16a.

  Furthermore, in the said embodiment, although the sealing part 30 is provided on the 1st metal oxide layer 16b, the sealing part 30 does not need to be provided on the 1st metal oxide layer 16b. That is, the sealing part 30 may be provided directly on the metal substrate 11.

  Furthermore, in the said embodiment, although the electroconductive board | substrate 15 has not only the 1st metal oxide layer 16b but the 2nd metal oxide layer 16a, the electroconductive board | substrate 15 does not necessarily need to be a 2nd metal oxide layer. It is not necessary to have 16a.

  In the above embodiment, the sealing portion is configured by only one sealing portion 30 provided between the conductive substrate 15 of the working electrode 10 and the counter substrate 21 of the counter electrode 20. The two first sealing portions are configured by two first sealing portions provided so as to sandwich the conductive substrate 15 of the working electrode 10 and a second sealing portion provided on the counter substrate 21 of the counter electrode 20. It is preferable that one of the parts and the second sealing part be bonded. Here, a part of the two first sealing portions is bonded to the conductive substrate 15 of the working electrode 10, and the remaining portion is bonded to the other first sealing portion. In this case, even when a flexible substrate is used as the counter substrate 21 of the counter electrode 20 and the photoelectric conversion element 100 is curved, the durability of the photoelectric conversion element 100 can be further improved. Here, examples of the flexible substrate include resin substrates such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), and polyether sulfone (PES).

  In the above embodiment, both the conductive substrate 15 and the counter substrate 21 have flexibility, but either one or both of the conductive substrate 15 and the counter substrate 21 have flexibility. It does not have to be.

  In the above embodiment, the counter substrate 21 has conductivity. However, if a counter electrode is separately provided on the semiconductor layer 13 side of the counter substrate 21, the counter substrate 21 does not have conductivity. May be. However, in this case, not only the counter substrate 21 but also the counter electrode needs to be transparent.

  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
(Production of working electrode)
First, a metal substrate made of titanium having a thickness of 50 μm is prepared, and a titanium oxide paste containing titanium oxide for forming a semiconductor layer is applied on the metal substrate by screen printing, and dried at 150 ° C. for 10 minutes to obtain a semiconductor. A dried body forming paste was obtained. Thus, an unfired substrate was obtained.

Thereafter, this unfired substrate was put in an oven, and the dried semiconductor layer forming paste was fired at 500 ° C. for 30 minutes to form a 10 μm-thick semiconductor layer on the metal substrate to obtain a working electrode. At this time, when the surface of the metal substrate was observed with a scanning electron microscope (SEM), thin layers were formed on both surfaces of the metal substrate. When this layer was analyzed by X-ray photoelectron spectroscopy (XPS), it was found that this layer was a metal oxide layer made of TiO ₂ . Moreover, when the thickness of these metal oxide layers was measured, it turned out that it is 100-200 nm.

Further, when the sheet resistance was measured by the four-terminal method for the working electrode, the value of the sheet resistance was 9.2 × 10 ⁻³ Ω / □ as shown in Table 1.

(Supporting photosensitizing dye)
Next, Z907 dye, which is a photosensitizing dye, was dissolved in a mixed solvent in which acetonitrile and t-butyl alcohol were mixed at 1: 1 (volume ratio) to prepare a dye solution. Then, the working electrode was immersed in this dye solution for 24 hours, and the photosensitizing dye was supported on the semiconductor layer.

(Production of counter electrode)
On the other hand, an ITO / PEN film (manufactured by Pexel Technologies) with an ITO film formed on a polyethylene naphthalate film (PEN film) is prepared as a counter substrate, and Pt which is a catalyst layer is deposited on this substrate by sputtering. I let you. In this way, a counter electrode was obtained.

(Preparation of sealing part)
Next, on the working electrode, an annular thermoplastic resin sheet made of high Milan (trade name, manufactured by Mitsui DuPont Polychemical Co., Ltd.), which is an ionomer, was placed. At this time, the semiconductor layer was arranged inside the annular thermoplastic resin sheet. The thermoplastic resin sheet was heated and melted at 180 ° C. for 5 minutes to adhere to the working electrode.

(Position of electrolyte)
On the other hand, an electrolyte was prepared by adding I ₂ , n-butylbenzimidazole (NBB) to a mixture of dimethylpropylimidazolium iodide and 3-methoxypropionitrile. And the prepared electrolyte was apply | coated so that the semiconductor layer of a working electrode might be covered with the dripping method.

(Sealing)
The counter electrode was superposed on the working electrode so that the electrolyte was sandwiched between the working electrode and the sealed portion was heated and melted under reduced pressure (1000 Pa) to bond the counter electrode and the sealed portion. Thus, a photoelectric conversion element composed of a single photoelectric conversion cell was obtained.

(Example 2)
By changing the firing time of the dried semiconductor layer forming paste from 30 minutes to 60 minutes, as shown in Table 1, the thickness of the metal oxide layer formed on the metal substrate is set to 300 to 400 nm. A photoelectric conversion element was produced in the same manner as in Example 1 except that the sheet resistance value of the electrode was 9.3 × 10 ⁻³ Ω / □.

(Example 3)
Before applying the semiconductor layer forming paste on the metal substrate, a pre-annealing process is performed on the metal substrate at 450 ° C. for 60 minutes, thereby forming a metal oxide layer formed on the metal substrate as shown in Table 1. A photoelectric conversion element was produced in the same manner as in Example 1 except that the thickness was set to 200 to 400 nm.

Example 4
Before applying the semiconductor layer forming paste on the metal substrate, a pre-annealing process is performed on the metal substrate at 500 ° C. for 60 minutes, thereby forming a metal oxide layer formed on the metal substrate as shown in Table 1. A photoelectric conversion element was produced in the same manner as in Example 1 except that the thickness of the film was 300 to 500 nm and the sheet resistance value of the working electrode was 9.3 × 10 ⁻³ Ω / □.

(Comparative Example 1)
Before applying the semiconductor layer forming paste on the metal substrate, a pre-annealing process is performed on the metal substrate at 600 ° C. for 60 minutes, so that the metal oxide layer formed on the metal substrate as shown in Table 1 A photoelectric conversion element was produced in the same manner as in Example 1 except that the thickness of the film was set to a thickness greater than 500 nm and the sheet resistance value of the working electrode was set to 9.7 × 10 ⁵ Ω / □.

[Characteristic evaluation]
For the photoelectric conversion elements of Examples 1 to 4 and Comparative Example 1 obtained as described above, photoelectric conversion characteristics and durability were evaluated.

(1) Photoelectric conversion characteristics About the photoelectric conversion elements of Examples 1 to 4 and Comparative Example 1 obtained as described above, initial photoelectric conversion efficiency η0 (%) was measured under an illuminance of 200 lux. The results are shown in Table 1.
At this time, the initial photoelectric conversion efficiency was measured using a Xe lamp solar simulator (YSS-150 manufactured by Yamashita Denso Co., Ltd.) and an IV tester (MP-160 manufactured by Eiko Seiki Co., Ltd.).

(2) Durability For the photoelectric conversion elements of Examples 1 to 4 and Comparative Example 1 obtained as described above, the adhesion of the semiconductor layer to the metal substrate is evaluated according to “JIS K 5600 paint general test method”. Thus, the durability was evaluated. The results are shown in Table 1. In Table 1, “◎”, “◯”, and “×” are represented based on the following criteria, respectively.

A: The semiconductor layer was not peeled off from the metal substrate at all. ○: The semiconductor layer was peeled off slightly from the metal substrate, but it did not affect the photoelectric conversion characteristics. The semiconductor layer was considerably peeled from the substrate

  From the results shown in Table 1, it can be seen that the photoelectric conversion elements of Examples 1 to 4 have considerably higher photoelectric conversion efficiency than the photoelectric conversion element of Comparative Example 1, and the adhesion of the semiconductor layer to the metal substrate is also good. It was.

  Therefore, according to the photoelectric conversion element of the present invention, it was confirmed that the photoelectric conversion characteristics can be improved and the durability is excellent.

DESCRIPTION OF SYMBOLS 10 ... Working electrode 11 ... Metal substrate 13 ... Semiconductor layer 15 ... Conductive substrate 15a ... 1st long side 15b ... 2nd long side 15c ... Line segment which connects the point of the both ends of 2nd long side 16a ... 2nd metal oxide Layer 16b ... 1st metal oxide layer 17 ... Connection terminal 20 ... Counter electrode 21 ... Opposite substrate 30 ... Sealing part 40 ... Electrolyte 50 ... Photoelectric conversion cell 100 ... Photoelectric conversion element

Claims (4)

Comprising at least one photoelectric conversion cell;
The photoelectric conversion cell is
A conductive substrate;
A semiconductor layer provided on the conductive substrate;
A transparent counter substrate disposed to face the conductive substrate;
A sealing portion provided to connect the conductive substrate and the counter substrate;
An electrolyte disposed between the conductive substrate and the counter substrate;
A photoelectric conversion element in which light is incident on the at least one photoelectric conversion cell from the counter substrate,
The conductive substrate is
A metal substrate;
A first metal oxide layer, which is provided on the metal substrate so as to be in contact with the semiconductor layer, and is composed of an oxide of a metal constituting the metal substrate;
The photoelectric conversion element whose thickness of the said 1st metal oxide layer is 100-500 nm.   The photoelectric conversion element according to claim 1, wherein the sealing portion includes a resin and is provided on the first metal oxide layer. The conductive substrate is provided on the opposite side of the metal substrate from the semiconductor layer, and further includes a second metal oxide layer made of a metal oxide constituting the metal substrate;
The photoelectric conversion element according to claim 1, wherein the photoelectric conversion element further includes a connection terminal provided on the second metal oxide layer.   The photoelectric conversion element according to any one of claims 1 to 3, wherein the conductive substrate and the counter substrate have flexibility.

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