JP2012186032A - Dye-sensitized solar battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dye-sensitized solar battery improved in its photoelectric conversion property, and having good durability.SOLUTION: The dye-sensitized solar battery 100 comprises: an action electrode 1; a counter electrode 2 opposed to the action electrode 1; and an electrolyte 4 located between the action electrode 1 and the counter electrode 2. The action electrode 1 has: a transparent conductive substrate 5; a first porous oxide semiconductor layer 6 formed on a face of the transparent conductive substrate 5 on the side of the counter electrode 2, and including first oxide semiconductor particles; a wiring part 8 provided on the face of the transparent conductive substrate 5 on the side of the counter electrode 2, to be spaced apart from the first porous oxide semiconductor layer 6, and surround the first porous oxide semiconductor layer 6; and a second porous oxide semiconductor layer 7 formed in contact with the transparent conductive substrate 5 to cover a gap region between the wiring part 8 and the first porous oxide semiconductor layer 6, and including second oxide semiconductor particles. The average particle diameter of the second oxide semiconductor particles is larger than the average particle diameter of the whole first oxide semiconductor particles that the first porous oxide semiconductor layer 6 includes.

Description

  The present invention relates to a dye-sensitized solar cell.

  In recent years, a dye-sensitized solar cell has attracted attention as a photoelectric conversion element because it is inexpensive and can provide high photoelectric conversion efficiency.

  A dye-sensitized solar cell generally includes a working electrode, a counter electrode, a photosensitizing dye carried on the working electrode, and an electrolyte disposed between the working electrode and the counter electrode.

  As such a dye-sensitized solar cell, for example, one described in Patent Document 1 is known. In Patent Document 1, a working electrode having a transparent conductive substrate and an oxide semiconductor layer formed on the transparent conductive substrate, a counter electrode disposed opposite to the working electrode, and a working electrode and the counter electrode are arranged. An electrolyte, a sealing material that connects the working electrode and the counter electrode, and seals the periphery of the electrolyte; and a current collector wiring formed on the transparent conductive substrate in a region where the oxide semiconductor layer is not formed; In addition, a dye-sensitized solar cell including a wiring protective layer that protects current collecting wiring from an electrolyte is disclosed.

JP 2010-198835 A

  However, the dye-sensitized solar cell described in Patent Document 1 described above has the following problems.

That is, in the dye-sensitized solar cell described in Patent Document 1, there is a gap region where nothing is formed between the oxide semiconductor layer on the transparent conductive substrate and the wiring protective layer, and thus the following problems are present. Arise.
(1) Light incident on the gap region is not absorbed by the oxide semiconductor layer and thus does not contribute to improvement in photoelectric conversion characteristics.
(2) There is a possibility that the transparent conductive substrate and the counter electrode are in direct contact with each other in the gap region, causing a short circuit.

  Here, in order to solve the above-described problem, it is conceivable that the oxide semiconductor layer is expanded and closely adhered to the wiring protective layer so as to fill all gap regions. However, in this case, when the dye-sensitized solar cell is used for a long period of time, a phenomenon that the generated current gradually decreases or the dye-sensitized solar cell is broken is observed. That is, such a dye-sensitized solar cell is insufficient in terms of durability.

  For this reason, the dye-sensitized solar cell which has the outstanding durability, improving a photoelectric conversion characteristic was calculated | required.

  This invention is made | formed in view of the said situation, and it aims at providing the dye-sensitized solar cell which can have outstanding durability, improving a photoelectric conversion characteristic.

  In the case where the oxide semiconductor layer is expanded so as to fill all the gap regions and are in close contact with the wiring protective layer, the present inventors have gradually reduced the generated current due to long-term use of the dye-sensitized solar cell, As a result of investigating the cause of the phenomenon of the breakage of the dye-sensitized solar cell, it was thought that a decrease in the limiting current of the dye-sensitized solar cell might be the cause of the above phenomenon. That is, the present inventors first found that the limit current is affected by the ease of passage of the electrolyte to the porous semiconductor layer. That is, the present inventors have found that the limiting current increases when the electrolyte easily passes through the porous semiconductor layer and decreases when it does not easily pass through the porous semiconductor layer. According to the knowledge of the present inventors, the oxide semiconductor layer is composed of particles having a small particle size (generally about several to 50 nm), and the gap between the particles is narrow, so that the electrolyte is a porous semiconductor layer. The present inventors thought that it was difficult to pass through and the limit current could not be said to be sufficiently large. For this reason, the present inventors considered that the reduction of the limit current cannot be suppressed only by expanding the oxide semiconductor layer and closely contacting the wiring protective layer. In this case, when the limit current is lower than the generated current, the generated current simply decreases. In addition, even if the limit current is larger than the generated current, if this difference is small, if a reverse bias is applied to the cell, a large reverse voltage is applied to the cell, increasing the possibility of the cell being destroyed.

  Therefore, as a result of further earnest studies, the present inventors have reflected or reflected light in the gap region between the wiring portion having the current collecting wiring and the wiring protective layer and the porous oxide semiconductor layer (power generation layer). It has been found that the above problem can be solved by providing another porous oxide semiconductor layer made of oxide semiconductor particles that can be scattered, and the present invention has been completed.

  That is, the present invention comprises a working electrode, a counter electrode disposed opposite to the working electrode, and an electrolyte disposed between the working electrode and the counter electrode, wherein the working electrode includes a transparent conductive substrate, A first porous oxide semiconductor layer made of first oxide semiconductor particles, formed on the counter electrode side surface of the transparent conductive substrate, and the first porous layer on the counter electrode side surface of the transparent conductive substrate. A wiring portion provided so as to be separated from the porous oxide semiconductor layer and surrounding the first porous oxide semiconductor layer; and the wiring portion and the first porous oxide semiconductor layer which are in contact with the transparent conductive substrate And a second porous oxide semiconductor layer made of second oxide semiconductor particles formed by filling a gap region between the first oxide semiconductor particles and the average particle size of the second oxide semiconductor particles Average of the whole first oxide semiconductor particles constituting the oxide semiconductor layer It is a dye-sensitized solar cell, wherein greater than the diameter.

  According to this dye-sensitized solar cell, since the average particle diameter of the second oxide semiconductor particles is larger than the average particle diameter of the entire first oxide semiconductor particles constituting the first porous oxide semiconductor layer, Becomes more easily reflected or scattered by the second oxide semiconductor particles. For this reason, when light is incident on the first and second porous oxide semiconductor layers through the transparent conductive substrate, the light incident on the first porous oxide semiconductor layer is incident on the first porous oxide semiconductor layer. It is absorbed and contributes to power generation. On the other hand, the light incident on the second porous oxide semiconductor layer is reflected or scattered by the second porous oxide semiconductor layer and guided to the first porous oxide semiconductor layer. That is, light that is not incident on the first porous oxide semiconductor layer can also contribute to power generation. As a result, it is possible to improve the photoelectric conversion characteristics as compared with the case where the second porous oxide semiconductor layer is not provided. In addition, since the second porous oxide semiconductor layer is formed so as to fill the gap region between the wiring portion and the first porous oxide semiconductor layer, even if the counter electrode approaches the transparent conductive substrate due to external force. The contact between the transparent conductive substrate and the counter electrode can be prevented, and a short circuit between the transparent conductive substrate and the counter electrode can be prevented.

  In addition, since the average particle diameter of the second oxide semiconductor particles is larger than the average particle diameter of the entire first oxide semiconductor particles constituting the first porous oxide semiconductor layer, The gap between the second oxide semiconductor particles can be made wider than the average gap between the first oxide semiconductor particles in the first porous oxide semiconductor layer. For this reason, the electrolyte easily passes through the gaps between the second oxide semiconductor particles, and the limit current increases. Therefore, even if the dye-sensitized solar cell is used for a long time, it is possible to sufficiently prevent the generated current from gradually decreasing and the cell from being broken.

  As mentioned above, according to the dye-sensitized solar cell of this invention, it becomes possible to have outstanding durability, improving a photoelectric conversion characteristic.

  In the dye-sensitized solar cell, in the second porous oxide semiconductor layer, the thickness of at least a part of the portion in contact with the transparent conductive substrate is the thickness of the first porous oxide semiconductor layer. It is preferable that it is smaller than this.

  In this case, in the portion of the second porous oxide semiconductor layer whose thickness is smaller than that of the first porous oxide semiconductor layer, the distance that the electrolyte passes through the porous oxide semiconductor layer is short. For this reason, it becomes possible to further increase the limit current, and even when the dye-sensitized solar cell is used for a long period of time, it is possible to more sufficiently prevent the generated current from gradually decreasing or the cell from being broken. it can.

  In the dye-sensitized solar cell, a distance from the wiring portion to the first porous oxide semiconductor layer is preferably within 1 mm on the surface on the counter electrode side of the transparent conductive substrate.

  In this case, it is possible to effectively improve the photoelectric conversion characteristics as compared with the case where the distance from the wiring portion to the first porous oxide semiconductor layer exceeds 1 mm.

  In the dye-sensitized solar cell, it is preferable that the second porous oxide semiconductor layer covers at least a part of the surface on the counter electrode side of the first porous oxide semiconductor layer.

  Even if light is incident on the first porous oxide semiconductor layer, part of the light passes through without being absorbed. The transmitted light is reflected or scattered by the second porous oxide semiconductor layer covering at least a part of the surface on the counter electrode side of the first porous oxide semiconductor layer, and the first porous oxide semiconductor Re-incident on the layer. For this reason, it becomes possible to improve a photoelectric conversion characteristic more.

  In the dye-sensitized solar cell, the first porous oxide semiconductor layer is composed of a laminate of a plurality of layers, and the first oxide semiconductor particles constituting the outermost layer on the counter electrode side in the laminate. And the second oxide semiconductor particles constituting the second porous oxide semiconductor layer are made of the same material and have the same average particle diameter, which is closer to the transparent conductive substrate than the outermost layer. It is preferable that an average particle diameter of the first oxide semiconductor particles constituting the portion is smaller than an average particle diameter of the second oxide semiconductor particles.

  In this case, when light is incident on the first porous oxide semiconductor layer, part of the light is absorbed by the portion of the first porous oxide semiconductor layer closer to the transparent conductive substrate than the outermost layer. Then, light that has passed without being absorbed is reflected or scattered by the outermost layer on the counter electrode side of the first porous oxide semiconductor layer, and the transparent conductive substrate from the outermost layer of the first porous oxide semiconductor layer. It is incident again on the side part and absorbed again. For this reason, it becomes possible to improve a photoelectric conversion characteristic more.

  In the dye-sensitized solar cell, the wiring section includes a metal wiring provided on the surface on the counter electrode side of the transparent conductive substrate, and a wiring protective layer that covers the metal wiring and contacts the transparent conductive substrate. The second porous oxide semiconductor layer covers at least a part of the wiring portion, and transmits light to the extent that the wiring protection layer reaches the second porous oxide semiconductor layer. It is preferable that this is possible.

  In this case, light incident on the wiring protective layer through the transparent conductive substrate can pass through the wiring protective layer and be incident on the second porous oxide semiconductor layer. The light incident on the second porous oxide semiconductor layer is reflected or scattered by the second porous oxide semiconductor layer and incident on the first porous oxide semiconductor layer, contributing to power generation. For this reason, it becomes possible to improve a photoelectric conversion characteristic more.

  The dye-sensitized solar cell of the present invention is particularly useful when the counter electrode has flexibility.

  In this case, when the internal pressure rises or decreases due to a temperature change, or when stress is applied to the dye-sensitized solar cell such as when receiving an external force, the counter electrode has flexibility. Stress is absorbed and durability is improved. When the stress is absorbed by the dye-sensitized solar cell, the counter electrode is easily deformed, so that the counter electrode and the transparent conductive substrate come into contact with each other and a short circuit is likely to occur between them. However, in the present invention, since the second porous oxide semiconductor layer is formed by filling the gap region between the wiring portion and the first porous oxide semiconductor layer, the contact between the counter electrode and the transparent conductive substrate Is prevented, and a short circuit between the two is prevented.

  In the dye-sensitized solar cell of the present invention, the counter electrode has flexibility, and the dye-sensitized solar cell further includes a sealing portion that connects the working electrode and the counter electrode, and the working electrode and the counter electrode And it is particularly useful when the internal pressure of the cell space formed by the sealing portion is smaller than 101325 Pa at 25 ° C.

  This is due to the following reason. That is, when the internal pressure of the cell space is smaller than 101325 Pa at 25 ° C., the pressure of the cell space is normally in a negative pressure state with respect to the outside air. At this time, if the counter electrode has flexibility, the counter electrode is bent, and the distance (distance between the electrodes) between the counter electrode and the transparent conductive substrate can be shortened. For this reason, photoelectric conversion efficiency can be improved. When the distance between the counter electrode and the transparent conductive substrate is shortened, the counter electrode and the transparent conductive substrate are easily short-circuited. However, in the present invention, since the second porous oxide semiconductor layer is formed so as to fill the gap region between the wiring portion and the first porous oxide semiconductor layer, contact between the counter electrode and the transparent conductive substrate is prevented. This prevents a short circuit from occurring between the two.

  In the present invention, the average particle diameter of the entire first oxide semiconductor particles constituting the first porous oxide semiconductor layer is determined by an X-ray diffraction apparatus (XRD, fully automatic horizontal multipurpose manufactured by Rigaku). Mean particle diameter measured by X-ray diffractometer SmartLab).

In the present invention, the counter electrode is “flexible” means that both edges (each having a width of 5 mm) of the 50 mm × 200 mm sheet-like counter electrode are horizontally placed at a tension of 1 N in an environment of 20 ° C. The maximum deformation rate of deflection of the counter electrode when a load of 20 g weight is applied to the center of the counter electrode exceeds 20%. Here, the maximum deformation rate is the following formula:
Maximum deformation rate (%) = 100 × (maximum displacement / sheet electrode thickness)
The value calculated based on Therefore, for example, when a sheet-like counter electrode having a thickness of 0.04 mm is bent by applying a load as described above, and the maximum displacement is 0.01 mm, the maximum deformation rate is 25%. It has “flexibility”.

  ADVANTAGE OF THE INVENTION According to this invention, the dye-sensitized solar cell which can have the outstanding durability, improving a photoelectric conversion characteristic is provided.

It is sectional drawing which shows one Embodiment of the dye-sensitized solar cell of this invention. It is the elements on larger scale of FIG. It is sectional drawing which shows other embodiment of the dye-sensitized solar cell of this invention. It is sectional drawing which shows the 1st modification of a 2nd porous oxide semiconductor layer. . It is sectional drawing which shows the 2nd modification of a 2nd porous oxide semiconductor layer. It is sectional drawing which shows other embodiment of the dye-sensitized solar cell of this invention.

  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.

[First Embodiment]
FIG. 1 is a cross-sectional view showing a first embodiment of a dye-sensitized solar cell according to the present invention.

  As shown in FIG. 1, the dye-sensitized solar cell 100 includes a working electrode 1, a counter electrode 2 disposed so as to face the working electrode 1, a sealing portion 3 that connects the working electrode 1 and the counter electrode 2, and an action. An electrolyte 4 disposed in a cell space formed by the electrode 1, the counter electrode 2, and the sealing portion 3 is provided.

  The working electrode 1 includes a transparent conductive substrate 5 capable of transmitting light, a plurality of first porous oxide semiconductor layers 6 provided on the surface of the transparent conductive substrate 5 on the counter electrode 2 side, and a transparent conductive substrate. 5 on the surface of the counter electrode 2 side, spaced apart from the first porous oxide semiconductor layer 6 and surrounding the first porous oxide semiconductor layer 6; And a second porous oxide semiconductor layer 7 formed by filling a gap region between the porous oxide semiconductor layer 6 and the first porous oxide semiconductor layer 6.

  The transparent conductive substrate 5 includes a transparent substrate 9 and a transparent conductive film 10 provided on the transparent substrate 9.

  The wiring portion 8 includes a metal wiring 11 provided on the surface of the transparent conductive substrate 5 on the counter electrode 2 side, and a wiring protective layer 12 that covers the metal wiring 11 and contacts the transparent conductive substrate 5. The wiring unit 8 is a non-power generation unit that does not contribute to power generation.

  The first porous oxide semiconductor layer 6 is made of first oxide semiconductor particles, and the second porous oxide semiconductor layer 7 is made of second oxide semiconductor particles. Here, a photosensitizing dye is supported on the first oxide semiconductor particles. The second oxide semiconductor particles may or may not carry a photosensitizing dye. Moreover, the average particle diameter d2 of the second oxide semiconductor particles is larger than the average particle diameter d1 of the entire first oxide semiconductor particles constituting the first porous oxide semiconductor layer 6.

  The counter electrode 2 includes a counter electrode substrate 13 and a conductive catalyst film 14 that is provided on the working electrode 1 side of the counter electrode substrate 13 and promotes a reduction reaction on the surface of the counter electrode 2.

  The sealing part 3 connects the outer peripheral part of the wiring part 8 and the counter electrode 2.

  FIG. 2 is a partially enlarged view of FIG. As shown in FIG. 2, the second porous oxide semiconductor layer 7 is formed so as to fill a gap region A between the wiring portion 8 and the first porous oxide semiconductor layer 6. Specifically, the second porous oxide semiconductor layer 7 includes a first portion 7a that contacts the transparent conductive substrate 5, and a second portion that extends from the first portion 7a and covers the side surface of the first porous oxide semiconductor layer 6. A portion 7b, a third portion 7c covering a part of the surface of the first porous oxide semiconductor layer 6 on the counter electrode 2 side, and a fourth portion 7d covering a part of the wiring protective layer 12 are configured.

  In addition, the thickness of at least the first portion 7 a of the second porous oxide semiconductor layer 7 is smaller than the thickness of the first porous oxide semiconductor layer 6.

  According to the dye-sensitized solar cell 100 described above, the average particle diameter d2 of the second oxide semiconductor particles is larger than the average particle diameter d1 of the entire first oxide semiconductor particles in the first porous oxide semiconductor layer 6. The light is more likely to be reflected or scattered by the second oxide semiconductor particles. For this reason, when light is incident on the first porous oxide semiconductor layer 6 and the second porous oxide semiconductor layer 7 through the transparent conductive substrate 5, the light incident on the first porous oxide semiconductor layer 6. Is absorbed by the first porous oxide semiconductor layer 6 and contributes to power generation. On the other hand, the light incident on the second porous oxide semiconductor layer 7 is reflected or scattered by the second porous oxide semiconductor layer 7 and guided to the first porous oxide semiconductor layer 6. That is, light that is not incident on the first porous oxide semiconductor layer 6 can also contribute to power generation. As a result, photoelectric conversion characteristics can be improved. Moreover, since the 2nd porous oxide semiconductor layer 7 is formed so that the clearance gap area A between the wiring part 8 and the 1st porous oxide semiconductor layer 6 may be filled, the counter electrode 2 is transparently conductive by external force. Even when approaching the substrate 5, the contact between the transparent conductive substrate 5 and the counter electrode 2 is prevented, and the transparent conductive substrate 5 and the counter electrode 2 can be prevented from being short-circuited.

  Further, since the average particle diameter d2 of the second oxide semiconductor particles is larger than the average particle diameter d1 of the entire first oxide semiconductor particles, the gap between the second oxide semiconductor particles in the second porous oxide semiconductor layer 7 Can be made wider than the gaps between the first oxide semiconductor particles in the first porous oxide semiconductor layer 6. For this reason, the electrolyte 4 can easily pass through the gap between the second oxide semiconductor particles, and the limit current can be increased. Therefore, even if the dye-sensitized solar cell 100 is used for a long time, it is possible to sufficiently prevent the generated current from gradually decreasing and the cell from being broken.

  As described above, the dye-sensitized solar cell 100 can have excellent durability while improving the photoelectric conversion characteristics.

  In the dye-sensitized solar cell 100, in the second porous oxide semiconductor layer 7, the thickness of at least the first portion 7 a that is in contact with the transparent conductive substrate 5 is equal to that of the first porous oxide semiconductor layer 6. It is smaller than the thickness.

  For this reason, in the first portion 7a having a thickness smaller than that of the first porous oxide semiconductor layer 6 in the second porous oxide semiconductor layer 7, the electrolyte 4 passes through the porous oxide semiconductor layer. The distance becomes shorter. For this reason, it becomes possible to further increase the limiting current, and even when the dye-sensitized solar cell 100 is used for a long period of time, it is possible to more sufficiently prevent the generated current from gradually decreasing or the cell from being broken. Can do.

  Further, in the dye-sensitized solar cell 100, the third portion 7c of the second porous oxide semiconductor layer 7 covers a part of the surface of the first porous oxide semiconductor layer 6 on the counter electrode 2 side.

  In this case, even if light is incident on the first porous oxide semiconductor layer 6, part of the light passes through without being absorbed. The transmitted light is reflected or scattered by the third portion 7c of the second porous oxide semiconductor layer 7 covering a part of the surface on the counter electrode 2 side of the first porous oxide semiconductor layer 6, and the first porous oxide semiconductor layer 6 Re-incident on one porous oxide semiconductor layer 6. For this reason, it becomes possible to improve a photoelectric conversion characteristic more.

  In the present embodiment, the second portion 7 b of the second porous oxide semiconductor layer 7 also covers the side surface of the first porous oxide semiconductor layer 6. For this reason, the light that has not been absorbed by the first porous oxide semiconductor layer 6 out of the light incident on the first porous oxide semiconductor layer 6 is the second portion of the second porous oxide semiconductor layer 7. 7b. At this time, light is reflected or scattered by the second portion 7 b and reenters the first porous oxide semiconductor layer 6. This also contributes to further improvement of the photoelectric conversion characteristics.

  Next, the working electrode 1, the photosensitizing dye, the counter electrode 2, the sealing portion 3 and the electrolyte 4 will be described in detail.

<Working electrode>
As described above, the working electrode 1 includes the transparent conductive substrate 5, the first porous oxide semiconductor layer 6, the second porous oxide semiconductor layer 7, and the wiring portion 8. The transparent conductive substrate 5 includes the transparent substrate 9 and the transparent conductive film 10 as described above.

(Transparent substrate)
The material which comprises the transparent substrate 9 should just be a transparent material, for example, As such a transparent material, glass, such as borosilicate glass, soda lime glass, white plate glass, quartz glass, polyethylene terephthalate (PET), for example , Polyethylene naphthalate (PEN), polycarbonate (PC), polyethersulfone (PES) and the like. The thickness of the transparent substrate 9 is appropriately determined according to the size of the dye-sensitized solar cell 100 and is not particularly limited, but may be in the range of 50 μm to 10000 μm, for example.

(Transparent conductive film)
Examples of the material forming the transparent conductive film 10 include tin-doped indium oxide (Indium-Tin-Oxide: ITO), tin oxide (SnO ₂ ), and fluorine-doped tin oxide (Fluorine-doped-Tin-Oxide: FTO). Examples include conductive metal oxides. The transparent conductive film 10 may be a single layer or a laminate of a plurality of layers made of different conductive metal oxides. When the transparent conductive film 10 is composed of a single layer, the transparent conductive film 10 is preferably composed of FTO because it has high heat resistance and chemical resistance. In addition, it is preferable to use a laminate composed of a plurality of layers as the transparent conductive film 10 because the characteristics of each layer can be reflected. Among these, it is preferable to use a laminate of a layer made of ITO and a layer made of FTO. In this case, the transparent conductive film 10 having high conductivity, heat resistance and chemical resistance can be realized. The thickness of the transparent conductive film 10 may be in the range of 0.01 μm to 2 μm, for example.

(First porous oxide semiconductor layer)
The first porous oxide semiconductor layer 6 is composed of first oxide semiconductor particles. The first oxide semiconductor particles are, for example, titanium oxide (TiO ₂ ), silica (SiO ₂ ), zinc oxide (ZnO), tungsten oxide (WO ₃ ), niobium oxide (Nb ₂ O ₅ ), strontium titanate (SrTiO _3). ), Tin oxide (SnO ₂ ), indium oxide (In ₃ O ₃ ), zirconium oxide (ZrO ₂ ), thallium oxide (Ta ₂ O ₅ ), lanthanum oxide (La ₂ O ₃ ), yttrium oxide (Y ₂ O ₃₎ ), Holmium oxide (Ho ₂ O ₃ ), bismuth oxide (Bi ₂ O ₃ ), cerium oxide (CeO ₂ ), aluminum oxide (Al ₂ O ₃ ), or two or more thereof.

  The average particle diameter d1 of the entire first oxide semiconductor particles is usually 4 to 100 nm. When the average particle diameter of the first oxide semiconductor particles is within the above range, it becomes easier to absorb light than when the first oxide semiconductor particles are out of the above range. The average particle diameter d1 of the first oxide semiconductor particles is preferably 15 to 80 nm, and more preferably 15 to 60 nm.

  The thickness of the 1st porous oxide semiconductor layer 6 should just be 0.5-50 micrometers, for example.

  The distance between the first porous oxide semiconductor layer 6 and the wiring portion 8 on the surface on the counter electrode 2 side of the transparent conductive substrate 5 is usually 5 mm or less, but preferably 1 mm or less. In this case, the photoelectric conversion characteristics can be effectively improved as compared with the case where the distance between the first porous oxide semiconductor layer 6 and the wiring portion 8 exceeds 1 mm.

  However, from the viewpoint of obtaining superior durability, the distance between the first porous oxide semiconductor layer 6 and the wiring portion 8 is preferably 0.2 mm or more, and preferably 0.4 mm or more. More preferred.

(Second porous oxide semiconductor layer)
The second porous oxide semiconductor layer 7 is made of second oxide semiconductor particles. The second oxide semiconductor particles are made of the same material as the first oxide semiconductor particles. The second oxide semiconductor particles may be made of a material different from that of the first oxide semiconductor particles, or may be made of the same material.

  The average particle diameter d2 of the second oxide semiconductor particles only needs to be larger than the average particle diameter of the entire first oxide semiconductor particles. The average particle diameter d2 of the second oxide semiconductor particles is usually 35 to 1000 nm. When the average particle diameter d2 of the second oxide semiconductor particles is within the above range, light is likely to be scattered or reflected as compared with a case outside the above range. The average particle diameter d2 of the second oxide semiconductor particles is preferably 50 to 500 nm, and more preferably 100 to 400 nm.

  The reference surface of the second porous oxide semiconductor layer 7 is different depending on the first to fourth portions 7a to 7d. That is, the surface to be covered by the first to fourth portions 7a to 7d becomes the reference surface for thickness. Specifically, the thickness of the first portion 7a is based on the surface of the transparent conductive substrate 5 on the counter electrode 2 side, and the thickness from that surface is the thickness of the first portion 7a. The thickness of the second portion 7b is based on the side surface of the first porous oxide semiconductor layer 6, and the thickness from that surface is the thickness of the second portion 7b. The thickness of the third portion 7c is based on the surface of the first porous oxide semiconductor layer 6 on the counter electrode 2 side, and the thickness from that surface is the thickness of the third portion 7c. The thickness of the fourth portion 7d is based on the surface of the wiring protective layer 12, and the thickness from the surface is the thickness of the fourth portion 7d. In the present embodiment, the thickness of at least the first portion 7 a among the first to fourth portions 7 a to 7 d of the second porous oxide semiconductor layer 7 is smaller than the thickness of the first porous oxide semiconductor layer 6. ing. Here, the difference in thickness between the first portion 7a and the first porous oxide semiconductor layer 6 may specifically be 5 to 40 μm. The difference in thickness between the first portion 7a and the first porous oxide semiconductor layer 6 is preferably 10 to 30 μm.

(Wiring section)
As described above, the wiring portion 8 is composed of the metal wiring 11 and the wiring protective layer 12.

  The metal wiring 11 should just be a material which has resistance lower than the transparent conductive film 10, and as such a material, metals, such as gold | metal | money, silver, copper, platinum, aluminum, titanium, and nickel, are mentioned, for example.

  Examples of the material constituting the wiring protective layer 12 include a material capable of transmitting light, such as a non-lead low melting point glass frit, and a lead oxide based glass frit that cannot transmit light. Materials. Of these, materials capable of transmitting light are preferable. Here, the degree of light transmission is preferably such that the light incident on the wiring protective layer 12 can reach the fourth portion 7 d of the second porous oxide semiconductor layer 7.

  In this case, light incident on the wiring protective layer 12 through the transparent conductive substrate 5 can pass through the wiring protective layer 12 and be incident on the fourth portion 7d of the second porous oxide semiconductor layer 7. Become. The light incident on the fourth portion 7d of the second porous oxide semiconductor layer 7 is incident on the first porous oxide semiconductor layer 6 and contributes to power generation. For this reason, it becomes possible to improve a photoelectric conversion characteristic more.

<Photosensitizing dye>
Examples of the photosensitizing dye include a ruthenium complex having a ligand containing a bipyridine structure, a terpyridine structure, and the like, and organic dyes such as porphyrin, eosin, rhodamine, and merocyanine.

<Counter electrode>
As described above, the counter electrode 2 includes the counter electrode substrate 13 and the conductive catalyst film 14 that is provided on the working electrode 1 side of the counter electrode substrate 13 and promotes the reduction reaction on the surface of the counter electrode 2.

(Counter electrode substrate)
The counter electrode substrate 13 is composed of, for example, a corrosion-resistant metal material such as titanium, nickel, platinum, molybdenum, or tungsten, or a film formed of a conductive oxide such as ITO or FTO on the transparent substrate 9 described above. The thickness of the counter electrode substrate 13 is appropriately determined according to the size of the dye-sensitized solar cell 100 and is not particularly limited, but may be, for example, 0.005 mm to 0.1 mm. Here, when the thickness of the counter electrode substrate 13 is particularly 0.005 mm to 0.035 μm, the counter electrode 2 can be provided with flexibility.

(Catalyst membrane)
The catalyst film 14 is made of platinum, a carbon-based material, a conductive polymer, or the like. Here, carbon nanotubes are suitably used as the carbon-based material.

<Sealing part>
The sealing part 3 is comprised by the resin sealing part containing resin, for example.

  Examples of the material constituting the resin sealing portion include ionomer, ethylene-vinyl acetic anhydride copolymer, ethylene-methacrylic acid copolymer, ethylene-vinyl alcohol copolymer, ultraviolet curable resin, and vinyl alcohol polymer. And other resins. In addition, the resin sealing part may be comprised only with resin, and may be comprised with resin and an inorganic filler.

<Electrolyte>
The electrolyte 4 includes, for example, a redox couple such as I ⁻ / I ₃ ^— and an organic solvent. As the organic solvent, acetonitrile, methoxyacetonitrile, methoxypropionitrile, propionitrile, ethylene carbonate, propylene carbonate, diethyl carbonate, γ-butyrolactone, and the like can be used. Examples of the redox pair include I ⁻ / I ₃ ⁻ and bromine / bromide ion pairs. A gelling agent may be added to the volatile solvent. Moreover, the electrolyte 4 may be comprised with the ionic liquid electrolyte which consists of a mixture of an ionic liquid and a volatile component. 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. As such a room temperature molten salt, for example, 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide is preferably used. As the volatile component, the above and an organic solvent, 1-methyl-3-methyl imidazolium iodide, _LiI, and the like I 2, 4-t-butylpyridine.

  Next, the manufacturing method of the dye-sensitized solar cell 100 is demonstrated.

<Working electrode formation process>
First, the working electrode 1 is prepared as follows.

  First, the transparent conductive film 10 is formed on the transparent substrate 9 to prepare the transparent conductive substrate 5. As a method for forming the transparent conductive film 10, a sputtering method, a vapor deposition method, a spray pyrolysis (SPD) method, a CVD method, or the like is used. Of these, the spray pyrolysis method is preferable from the viewpoint of apparatus cost.

(First porous oxide semiconductor layer forming step)
Next, a paste for forming a first porous oxide semiconductor layer containing first oxide semiconductor particles is printed on the transparent conductive film 10.

  Next, the first porous oxide semiconductor layer forming paste is baked to form the first porous oxide semiconductor layer 6 on the transparent conductive film 10.

(Wiring section forming process)
Next, the metal wiring 11 is formed on the transparent conductive substrate 5. The metal wiring 11 can be formed, for example, by applying and baking a metal paste so as to be separated from the first porous oxide semiconductor layer 6 and surround the first porous oxide semiconductor layer 6. Subsequently, a wiring protective layer 12 is formed so as to cover the metal wiring 11 and to be in contact with the transparent conductive substrate 5. The wiring protective layer 12 can be formed by, for example, applying a paste containing a low melting point glass frit so as to cover the metal wiring 11 and drying it, followed by firing. In this way, the wiring part 8 is obtained.

(Second porous oxide semiconductor layer forming step)
After obtaining the wiring part 8 in this way, the gap region A between the wiring part 8 and the first porous oxide semiconductor layer 6 is filled and a part of the wiring protection layer 12 is covered, and the first porous oxide semiconductor layer A second porous oxide semiconductor layer 7 is formed so as to cover a part of the surface of 6 on the counter electrode 2 side.

  The second porous oxide semiconductor layer 7 fills the gap region A between the wiring portion 8 and the first porous oxide semiconductor layer 6 and covers a part of the wiring protective layer 12, It may be formed by printing and baking a second porous oxide semiconductor layer forming paste containing second oxide semiconductor particles so as to cover part of the surface of the semiconductor layer 6 on the counter electrode 2 side. it can. At this time, as the second porous oxide semiconductor particles, those having an average particle diameter d2 larger than the average particle diameter d1 of the entire first oxide semiconductor particles are used.

  The first and second porous oxide semiconductor layer forming pastes contain a resin such as polyethylene glycol and a solvent such as terpineol in addition to the first and second oxide semiconductor particles described above. As a printing method of the first and second porous oxide semiconductor layer forming pastes, for example, a screen printing method, a doctor blade method, a bar coating method, or the like can be used.

  Although the firing temperature varies depending on the material of the first and second oxide semiconductor particles, it is usually 350 ° C. to 600 ° C., and the firing time also varies depending on the material of the first and second oxide semiconductor particles. ~ 5 hours.

  Thus, the working electrode 1 is obtained.

<Dye supporting step>
Next, the photosensitizing dye is supported on the first porous oxide semiconductor layer 6 of the working electrode 1. For this purpose, the working electrode 1 is immersed in a solution containing a photosensitizing dye, and the dye is adsorbed on the first porous oxide semiconductor layer 6 and then an extra dye is added with the solvent component of the solution. The photosensitizing dye may be adsorbed to the first porous oxide semiconductor layer 6 by washing away and drying. However, even if the photosensitizing dye is adsorbed to the oxide semiconductor porous film by applying a solution containing the photosensitizing dye to the first porous oxide semiconductor layer 6 and then drying it, It can be supported on the first porous oxide semiconductor layer 6. At this time, a photosensitizing dye may be supported on the second porous oxide semiconductor layer 7.

<Counter electrode preparation process>
On the other hand, the counter electrode 2 is prepared as follows.

  First, the counter electrode substrate 13 is prepared. Then, the catalyst film 14 is formed on the counter electrode substrate 13. As a method for forming the catalyst film 14, a sputtering method, a vapor deposition method, or the like is used. Of these, sputtering is preferred from the viewpoint of film uniformity. In this way, the counter electrode 2 is obtained.

<Sealing part fixing process>
Next, for example, an annular sheet made of a thermoplastic resin is prepared. And it mounts on the wiring part 8 of the working electrode 1 which carry | supported the photosensitizing dye, and heat-melts a cyclic | annular sheet | seat. In this way, the annular sheet is fixed on the wiring portion 8 of the working electrode 1. An annular sheet is fixed to the counter electrode 2 in the same manner.

<Electrolyte placement process>
Next, the electrolyte 4 is prepared. Then, the electrolyte 4 is arranged inside the annular sheet provided on the working electrode 1. The electrolyte 4 can be disposed by a printing method such as screen printing.

  After the electrolyte 4 is disposed on the working electrode 1, the counter electrode 2 is overlapped with the working electrode 1 so that the electrolyte 4 is sandwiched between the working electrode 1 and the working electrode 1 and the counter electrode 2 are formed by an annular sheet. Adhere. Thus, the dye-sensitized solar cell 100 is obtained, and the manufacture of the dye-sensitized solar cell 100 is completed.

[Second Embodiment]
Next, a second embodiment of the dye-sensitized solar cell of the present invention will be described. In addition, the same code | symbol is attached | subjected about the component same or equivalent to 1st Embodiment, and the overlapping description is abbreviate | omitted.

  FIG. 3 is a cross-sectional view showing a second embodiment of the dye-sensitized solar cell of the present invention. As shown in FIG. 3, the dye-sensitized solar cell 200 of the present embodiment is different from the dye-sensitized solar cell 100 of the first embodiment in that the counter electrode 2 has flexibility.

  The second porous oxide semiconductor layer 7 is particularly useful when the counter electrode 2 of the dye-sensitized solar cell 200 shown in FIG. 3 has flexibility. In this case, since the counter electrode 2 has flexibility even when the internal pressure increases or decreases due to a temperature change or when stress is applied to the dye-sensitized solar cell 200 such as receiving external force. The stress is absorbed and the durability is improved. When the stress is absorbed by the dye-sensitized solar cell 200, the counter electrode 2 is easily deformed, so that the counter electrode 2 and the transparent conductive substrate 5 come into contact with each other, so that a short circuit is likely to occur between them. However, in the dye-sensitized solar cell 200, the second porous oxide semiconductor layer 7 is formed so as to fill the gap region between the wiring portion 8 and the first porous oxide semiconductor layer 6. 2 and the transparent conductive substrate 5 are prevented from contacting each other, and a short circuit between them is prevented from occurring.

  Here, the cell space of the dye-sensitized solar cell 200 may be 101325 Pa or more at 25 ° C. or smaller than 101325 Pa. However, the second porous oxide semiconductor layer 7 has a cell space of 101325 Pa at 25 ° C. More useful in small cases.

  This is due to the following reason. That is, when the cell space is smaller than 101325 Pa at 25 ° C., the cell space is normally in a negative pressure state with respect to the outside air. At this time, if the counter electrode 2 has flexibility, the counter electrode 2 bends, and the distance (distance between the electrodes) between the counter electrode 2 and the transparent conductive substrate 5 can be shortened. For this reason, photoelectric conversion efficiency can be improved. When the distance between the counter electrode 2 and the transparent conductive substrate 5 is shortened, the counter electrode 2 and the transparent conductive substrate 5 are easily short-circuited. However, in the dye-sensitized solar cell 200, the second porous oxide semiconductor layer 7 is formed so as to fill the gap region between the wiring portion 8 and the first porous oxide semiconductor layer 6. And the transparent conductive substrate 5 are sufficiently prevented from being short-circuited.

  The second porous oxide semiconductor layer 7 is more useful when the pressure in the cell space is 50 to 800 Pa at 25 ° C., and is particularly useful when the pressure is 300 to 800 Pa.

  In order to reduce the pressure in the cell space to less than 101325 Pa at 25 ° C., that is, to form a decompression space, for example, the following may be performed.

  That is, first, the working electrode 1 to which an annular resin sheet is fixed is housed in a decompression vessel having an opening. Subsequently, the electrolyte 4 is injected inside the annular resin sheet. Thereafter, the counter electrode 2 to which the annular resin sheet is fixed is further accommodated in the decompression container, and the working electrode 1 and the counter electrode 2 are opposed to each other in the decompression container. Next, the opening of the decompression container is closed with a flexible sheet made of a resin such as PET, and a sealed space is formed in the decompression container. Then, the sealed space is decompressed by, for example, a vacuum pump through an exhaust hole (not shown) formed in the decompression container. Thus, a reduced pressure space can be formed.

  When the decompression space is formed in this way, the counter electrode 2 is pressed by the flexible sheet. Along with this, the annular sheet is sandwiched and pressed by the working electrode 1 and the counter electrode 2. At this time, when the decompression container is heated and the annular sheet is melted while being pressurized, the sealing portion 3 connecting the working electrode 1 and the counter electrode 2 is obtained.

  The present invention is not limited to the above embodiment. For example, in the first and second embodiments, the second porous oxide semiconductor layer 7 is composed of the first portion 7a, the second portion 7b, the third portion 7c, and the fourth portion 7d. However, as shown in FIG. 4, the second portion 7b and the third portion 7c may be omitted. In other words, the second porous oxide semiconductor layer 7 may be composed of only the first portion 7a and the fourth portion 7d. Moreover, as shown in FIG. 5, the 2nd part 7b, the 3rd part 7c, and the 4th part 7d may be abbreviate | omitted. In other words, the second porous oxide semiconductor layer 7 may be composed of only the first portion 7a.

  Moreover, in the said 1st and 2nd embodiment, although the 1st porous oxide semiconductor layer 6 is comprised by the single layer, like the dye-sensitized solar cell 300 shown in FIG. The quality oxide semiconductor layer 6 may be composed of a stacked body including a first layer 6a in contact with the transparent conductive film 10 and a second layer 6b provided on the counter electrode 2 side of the first layer 6a. . The second layer 6b is the outermost layer on the counter electrode 2 side of the laminate. Here, the first oxide semiconductor particles constituting the second layer 6b and the second oxide semiconductor particles constituting the second porous oxide semiconductor layer 7 are made of the same material and are the same. It is preferable to have an average particle size of In addition, the average particle diameter of the 1st oxide semiconductor particle which comprises the 1st layer 6a is smaller than the average particle diameter of the 1st oxide semiconductor particle of the 2nd layer 6b. In this case, even if light is incident on the first porous oxide semiconductor layer 6, part of the light passes through the first layer 6a without being absorbed. The transmitted light is reflected or scattered by the second layer 6b which is the outermost layer of the first porous oxide semiconductor layer 6, and the first layer 6a closer to the transparent conductive film 10 than the second layer 6b. And is absorbed again by the first layer 6a. For this reason, it becomes possible to improve a photoelectric conversion characteristic more.

  In the first and second embodiments, the second porous oxide semiconductor layer 7 covers only a part of the wiring part 8, but may cover the whole wiring part 8.

  Furthermore, in the first and second embodiments, the thickness of at least the first portion 7 a of the second porous oxide semiconductor layer 7 is smaller than the thickness of the first porous oxide semiconductor layer 6. The thickness of the first porous oxide semiconductor layer 6 may be equal to or less than the thickness of any one of the first to fourth portions 7a to 7d of the second porous oxide semiconductor layer 7.

  Furthermore, in the first and second embodiments, the sealing portion 3 is connected to the wiring portion 8, but it is not always necessary that the wiring portion 8 and the sealing portion 3 are connected. Therefore, the electrolyte 4 may exist between the wiring portion 8 and the counter electrode 2.

  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 fluorine-doped tin oxide transparent conductive glass substrate (FTO substrate) of 10 cm × 10 cm × 4 mm (thickness) was prepared. Subsequently, a first titanium oxide nanoparticle paste (Solaronix, Ti nanoixide T / sp) containing first titanium oxide particles having an average particle diameter of 15 nm is applied onto the FTO substrate by screen printing to form a film. Produced. Then, this film-coated substrate was put in an oven and baked at 500 ° C. for 1 hour to form four first porous oxide semiconductor layers of 12 mm × 50 mm × 30 μm (thickness) on the FTO substrate. At this time, the first porous oxide semiconductor layers were formed so as to be separated from each other. Subsequently, a silver paste is applied on the FTO substrate so as to surround each of the four first porous oxide semiconductor layers, and fired at 500 ° C. for 1 hour to form a metal wiring having a thickness of 15 μm and a width of 1 mm. Formed. At this time, the silver paste was applied at a position 1 mm away from the first porous oxide semiconductor layer.

  Subsequently, a paste containing a low melting point glass frit is applied so as to cover the metal wiring, dried at 150 ° C. for 0.1 hour, and then baked at 500 ° C. for 1 hour, thereby having a thickness of 50 μm and a width of 1.5 mm. A wiring protective layer was formed to obtain a wiring portion. At this time, on the surface of the FTO substrate, the distance between the wiring portion and the first porous oxide semiconductor layer was 0.75 mm.

  Next, a second titanium oxide nanoparticle paste (Solaronix, Ti nanoixide R / sp) containing second titanium oxide particles having an average particle diameter of 400 nm was prepared. Then, the paste fills a gap region between the wiring portion and the first porous oxide semiconductor layer, covers a part of the wiring portion, and a part of the surface on the counter electrode side of the first porous oxide semiconductor layer The film was formed by coating so as to cover. Then, this board | substrate with a film | membrane was put into oven and baked at 500 degreeC for 1 hour, and the 2nd porous oxide semiconductor layer was formed. Regarding the thickness of the second porous oxide semiconductor layer, the thickness of the first portion contacting the FTO substrate is 5 μm, the thickness of the second portion is 35 μm, the thickness of the third portion is 5 μm, and the fourth portion. The thickness was 55 μm. Thus, a working electrode was obtained.

(Supporting photosensitizing dye)
Next, the photosensitizing dye was supported on the first porous oxide semiconductor layer of the working electrode by being immersed in a dehydrated ethanol solution in which 0.2 mM of N719 dye as a photosensitizing dye was dissolved for 24 hours.

(Production of counter electrode)
On the other hand, a metal substrate made of pure metal titanium foil was prepared, and after cleaning the surface of this metal substrate with a plasma, a platinum catalyst film having a thickness of about 30 nm was formed on the entire surface by sputtering to obtain a counter electrode.

(Preparation of sealing part)
Then, an annular thermoplastic resin sheet made of ionomer (trade name, manufactured by Mitsui DuPont Polychemical Co., Ltd.) is arranged on the annular portion on the platinum catalyst membrane of the counter electrode, and the thermoplastic resin sheet is heated at 180 ° C. for 5 minutes. And fixed by melting.

  In addition, an annular thermoplastic resin sheet made of high milan, which is an ionomer, is placed on the outer periphery of the wiring portion of the working electrode, and the thermoplastic resin sheet is heated and melted at 180 ° C. for 5 minutes to adhere to the working electrode and fixed. did.

(Electrolyte arrangement)
On the other hand, an ionic liquid (hexylmethylimidazolium iodide) containing an iodine / iodide ion redox pair was prepared. And this electrolyte was apply | coated to the working electrode which carry | supported the photosensitizing dye by the screen printing method so that the 1st and 2nd porous oxide semiconductor layer might be covered.

(Sealing)
Next, the counter electrode to which the resin sheet was fixed was made to face the working electrode and placed in a reduced pressure environment of about 500 hPa, and the resin sheet fixed to the counter electrode and the resin sheet fixed to the working electrode were overlapped. Then, under a reduced pressure environment, a brass frame of the same size as the resin sheet is heated, placed on the opposite side of the resin sheet with the brass frame on the counter electrode, and fixed to the counter electrode using a press. The resin sheet and the resin sheet fixed to the working electrode were melted by locally heating at a temperature of 160 ° C. while pressurizing at 5 MPa to form a sealing body. Then, this laminated body was taken out under atmospheric pressure. Thus, a dye-sensitized solar cell was obtained.

(Example 2)
Dye-sensitized solar in the same manner as in Example 1 except that the thickness of the first portion of the second porous oxide semiconductor layer that contacts the FTO substrate is the same as the thickness of the first porous oxide semiconductor layer. A battery was produced.

(Comparative Example 1)
A dye-sensitized solar cell was produced in the same manner as in Example 1 except that the second porous oxide semiconductor layer was not formed.

(Comparative Example 2)
A dye-sensitized solar cell was produced in the same manner as in Example 1 except that when the wiring part was formed, the distance between the wiring part and the first porous oxide semiconductor layer was 0 mm.

  For the dye-sensitized solar cells of Examples 1 and 2 and Comparative Examples 1 and 2 obtained as described above, the photoelectric conversion characteristics and the durability were examined as follows.

(Photoelectric conversion characteristics)
For the photoelectric conversion characteristics, photoelectric conversion efficiency η (%) was used as an index. Therefore, photoelectric conversion efficiency η (%) was measured for the dye-sensitized solar cells of Examples 1 and 2 and Comparative Examples 1 and 2. The results are shown in Table 1.

(durability)
Durability is based on the rate of decrease in generated current and the presence or absence of a short between the transparent conductive substrate and the counter electrode. The rate of decrease in generated current meets the acceptance criteria, and there is a short circuit between the transparent conductive substrate and the counter electrode. If not, the durability was evaluated to be excellent, and if the rate of decrease in the generated current did not satisfy the acceptance criteria, or a short circuit between the transparent conductive substrate and the counter electrode was observed, the durability was evaluated to be inferior. .

The rate of decrease in generated current was determined as follows. First, for the dye-sensitized solar cells of Examples 1 and 2 and Comparative Examples 1 and 2, initial power generation current I ₀ was measured. Subsequently, the generated current I ₁ after using the dye-sensitized solar cells of Examples 1 and 2 and Comparative Examples 1 and 2 in an environment of 85 ° C. and 85% RH for 500 hours was measured. And the reduction rate of the generated current is expressed by the following formula:
Reduction rate of generated current = 100 × (I ₁ −I ₀ ) / I ₀
Calculated based on The results are shown in Table 1. The acceptance criteria for the rate of decrease in generated current were as follows.
Pass: 5% or less Fail: Over 5%

As for the short circuit between the transparent conductive substrate and the counter electrode, the short circuit is assumed when the resistance value between the working electrode and the counter electrode is 10 kΩ or less. The results are shown in Table 1.

  From the results shown in Table 1, it was found that the dye-sensitized solar cells of Examples 1 and 2 showed higher photoelectric conversion efficiency than the dye-sensitized solar cells of Comparative Examples 1 and 2.

  From the results shown in Table 1, in the dye-sensitized solar cells of Examples 1 and 2, the reduction rate of the generated current satisfied the acceptance criteria, and no short circuit was observed. On the other hand, in the dye-sensitized solar cells of Comparative Examples 1 and 2, the rate of decrease in generated current did not satisfy the acceptance criteria, or a short circuit was observed. Therefore, it was also found that the dye-sensitized solar cells of Examples 1 and 2 were superior in durability to the dye-sensitized solar cells of Comparative Examples 1 and 2.

  Therefore, it was confirmed that the dye-sensitized solar cell of the present invention can have excellent durability while improving the photoelectric conversion characteristics.

DESCRIPTION OF SYMBOLS 1 ... Working electrode 2 ... Counter electrode 4 ... Electrolyte 5 ... Transparent conductive substrate 6 ... 1st porous oxide semiconductor layer 7 ... 2nd porous oxide semiconductor layer 8 ... Wiring part 11 ... Metal wiring 12 ... Wiring protective layer 100 ... Dye-sensitized solar cell

Claims (8)

Working electrode,
A counter electrode disposed opposite the working electrode;
An electrolyte disposed between the working electrode and the counter electrode,
The working electrode is
A transparent conductive substrate;
A first porous oxide semiconductor layer comprising first oxide semiconductor particles formed on the surface of the transparent conductive substrate on the counter electrode side;
A wiring portion provided on the surface on the counter electrode side of the transparent conductive substrate so as to be separated from the first porous oxide semiconductor layer and to surround the first porous oxide semiconductor layer;
A second porous oxide semiconductor layer comprising second oxide semiconductor particles formed in contact with the transparent conductive substrate and filling a gap region between the wiring portion and the first porous oxide semiconductor layer; Have
The average particle size of the second oxide semiconductor particles is larger than the average particle size of the entire first oxide semiconductor particles constituting the first porous oxide semiconductor layer. .   In the second porous oxide semiconductor layer, the thickness of at least a part of the portion in contact with the transparent conductive substrate is smaller than the thickness of the first porous oxide semiconductor layer. The dye-sensitized solar cell described.   The distance from the said wiring part to the said 1st porous oxide semiconductor layer is less than 1 mm in the surface by the side of the said counter electrode among the said transparent conductive substrates, It is any one of Claim 1 or 2 Dye-sensitized solar cell.   The dye enhancement according to any one of claims 1 to 3, wherein the second porous oxide semiconductor layer covers at least a part of the surface on the counter electrode side of the first porous oxide semiconductor layer. Sensitive solar cell.   The first porous oxide semiconductor layer is composed of a laminate of a plurality of layers, and the first oxide semiconductor particles and the second porous oxide semiconductor constituting the outermost layer on the counter electrode side of the laminate. The second oxide semiconductor particles constituting the layer are made of the same material and have the same average particle diameter, and the first oxide constituting the transparent conductive substrate side portion from the outermost layer The dye-sensitized solar cell according to any one of claims 1 to 4, wherein an average particle size of the semiconductor particles is smaller than an average particle size of the second oxide semiconductor particles. The wiring part has a metal wiring provided on the surface on the counter electrode side of the transparent conductive substrate, and a wiring protective layer that covers the metal wiring and contacts the transparent conductive substrate,
The second porous oxide semiconductor layer covers at least a part of the wiring portion, and light can be transmitted to such an extent that the wiring protection layer reaches the second porous oxide semiconductor layer. The dye-sensitized solar cell according to claim 1, wherein   The dye-sensitized solar cell according to any one of claims 1 to 6, wherein the counter electrode has flexibility. A sealing part for connecting the working electrode and the counter electrode;
The dye-sensitized solar cell according to claim 7, wherein a cell space formed by the working electrode, the counter electrode, and the sealing portion is smaller than 101325 Pa at 25 ° C.

Images