JP5311094B2 - Dye-sensitized solar cell and dye-sensitized solar cell module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dye-sensitized solar cell which is excellent in long durability, and a dye-sensitized solar cell module using the same dye-sensitized solar cell. <P>SOLUTION: The dye-sensitized solar cell includes two transparent conductive layers 3 separately formed on a substrate 1 having a light-transmitting property by separating at a predetermined distance, a light electrode 7 stacked on one of the transparent conductive layer 3 and having a n-type semiconductor layer 9 including a colorant 11 emitting electrons in response to light-receiving, a counter electrod 13 facing to the light electrode 7 at an equal area by separating at a predetermined distance, and an electrolyte layer 17 enclosed between the light electrode 7 and the counter electrod 13. The dye-sensitized solar cell has conductivity along the other side of the transparent conductive layer 3 and the counter electrod 13, and provides a connection section 21 having no function as a reducing catalyst. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

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

  2. Description of the Related Art In recent years, solar cells that generate electricity using natural light that falls inexhaustibly from the sun have been attracting attention with respect to problems such as global environment conservation and fossil energy resource depletion. In the currently popularized solar cell systems, silicon-based solar cells (solar cells using crystalline silicon or amorphous silicon) are the mainstream. However, these silicon-based solar cells have problems such as shortage of semiconductor silicon raw materials and high cost. Under such circumstances, dye-sensitized solar cells with few such problems have been developed. The dye-sensitized solar cell was developed in 1991 by Gretzer et al. At the University of Lausanne in Switzerland and is also called a Gretzell cell.

  This dye-sensitized solar cell includes a light-transmitting substrate, a transparent conductive layer laminated on the substrate, a photoelectrode, and a conductive counter electrode provided at a predetermined interval with respect to the photoelectrode. And an electrolyte layer enclosed between the photoelectrode and the counter electrode. The photoelectrode has an n-type semiconductor layer stacked on the transparent conductive layer and a dye supported on the n-type semiconductor layer. When this dye-sensitized solar cell is irradiated with light from the photoelectrode side, the dye absorbs light and generates electrons and holes. Holes move from the dye to the electrolyte layer and oxidize ions in the electrolyte solution. On the other hand, electrons move from the photoelectrode to the counter electrode via an external circuit, where they reduce ions in the electrolyte solution. An electromotive force is generated by the oxidation-reduction potential of the ion species, and the power generation action of the battery is obtained.

  Attempts have been made to modularize and integrate such dye-sensitized solar cells. For example, Patent Document 1 below describes the structure of a dye-sensitized solar cell in which only one conductive glass substrate is used and cells are integrated on the conductive glass substrate. In this dye-sensitized solar cell, as shown in FIG. 6, transparent conductive layers 102 are separately formed on a single transparent glass substrate 101 at a predetermined interval, and two transparent conductive layers 102 adjacent to each other are formed. A photoelectrode 103 is laminated on one of them. The counter electrode (carbon layer) 104 facing the photoelectrode 103 with a predetermined interval is formed in a cross-sectional L shape so as to cover one side of the photoelectrode, and is conducted to the other transparent conductive layer 102. An electrolyte layer 105 is sealed between the photoelectrode 103 and the counter electrode 104. By adopting such a structure, the amount of expensive and heavy conductive glass substrate can be reduced, so that the cost and weight can be reduced.

JP-A-2005-285781

  However, in the cell structure of the dye-sensitized solar cell described in Patent Document 1, the counter electrode facing the photoelectrode is formed in an L-shaped cross section so as to cover one side of the photoelectrode, The counter electrode always has a larger surface area than the photoelectrode. The counter electrode composed of a porous carbon layer sucks the electrolyte into its interior and functions as a catalyst for the reduction reaction of ions in the electrolyte, resulting in an overall imbalance between the size of the photoelectrode and the counter electrode. As a result, the reduction reaction of ions in the electrolyte proceeds more preferentially than the oxidation reaction. In particular, at the portion of the counter electrode that is not opposed to the photoelectrode, only the reduction reaction proceeds selectively and a concentration gradient of the redox pair is generated. Therefore, even if good power generation performance is demonstrated in the short term, the amount of active ionic species decreases as the use continues, the conductivity of the electrolyte decreases, the internal resistance of the battery increases, and the output decreases Will lead to. That is, the dye-sensitized solar cell having a cell structure as described in Patent Document 1 still has a point to be improved in terms of long-term durability.

  This invention is made | formed in view of the said subject, and it aims at providing the dye-sensitized solar cell excellent in long-term durability, and a dye-sensitized solar cell module using the same.

In order to achieve this object, the characteristic configuration of the dye-sensitized solar cell according to the present invention includes two transparent conductive layers formed on a single light-transmitting substrate with a predetermined interval therebetween, and A photoelectrode having an n-type semiconductor layer containing a dye that emits electrons upon receiving light, and is laminated on one of the transparent conductive layers, and an electrolyte layer is laminated on the photoelectrode and stores an electrolyte therein In the dye-sensitized solar cell provided with the separator layer as the above and a counter electrode laminated on the separator layer and containing carbon particles, the separator is provided across the other of the transparent conductive layer and the counter electrode. A contact portion extending perpendicularly to the substrate while being in contact with one end surface of the layer and contacting the counter electrode on a side surface thereof, the connection portion having conductivity and having a particle diameter of 1 to 50 nm; Baked from conductive oxide powder Constituted by the body, the conductive oxide powder is indium tin oxide, antimony tin oxide, at least made of any one or more selected from among fluorine doped tin oxide and conductive zinc oxide There is a point.

  According to the above characteristic configuration, in the dye-sensitized solar cell in which cells are formed on one substrate, the photoelectrode and the counter electrode are opposed to each other with a predetermined distance and at an equal area. For this reason, the progress of the reduction reaction and the oxidation reaction of ions in the electrolytic solution can be made substantially equal. In addition, since the transparent conductive layer and the counter electrode are connected by a connection portion that has conductivity and does not function as a reduction catalyst, only a reduction reaction is performed at the connection portion while ensuring an appropriate flow of generated electrons. Can be prevented from proceeding selectively. Accordingly, it is possible to provide a dye-sensitized solar cell excellent in long-term durability by suppressing the occurrence of a redox pair concentration gradient.

Moreover, according to this structure, the dye-sensitized solar cell excellent in long-term durability can be provided easily using the material generally spread as electroconductive oxide powder.

  The conductive oxide has conductivity, and a redox reaction hardly occurs on the surface thereof. Therefore, if the connection portion is formed using a conductive oxide by adopting the above configuration, a dye-sensitized solar cell excellent in long-term durability can be obtained by suppressing the occurrence of a redox pair concentration gradient. Can be provided.

According to this structure, since the connection part is formed on the transparent conductive layer by using a fine conductive oxide powder having a particle diameter of 1 to 50 nm as a raw material, the transparent conductive layer and the connection part are densely formed. Can be bound. Therefore, the mechanical strength against external force, expansion / contraction stress, and the like at the binding site can be improved, and the long-term durability of the dye-sensitized solar cell can be improved from this point.
The connecting portion is formed by laminating and baking paste containing the conductive oxide powder by screen printing after forming the separator layer, and the counter electrode forms the connecting portion. After that, it is preferable that the paste containing carbon particles and oxide particles having binding properties is formed by screen printing and laminated so as to fill the step between the connection portion and the separator layer and then fired. .

  The characteristic configuration of the dye-sensitized solar cell module according to the present invention is that a plurality of dye-sensitized solar cells as described above are used and connected in series.

  According to this characteristic configuration, it is possible to take out a predetermined amount of power by connecting dye-sensitized solar cells excellent in long-term durability in series, and the entire dye-sensitized solar cell module The long-term durability can be improved.

[First embodiment]
A first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing the overall structure of a dye-sensitized solar cell module M according to the present invention. As shown in this figure, in the dye-sensitized solar cell module M according to this embodiment, a plurality of dye-sensitized solar cells C (hereinafter sometimes referred to as cells) are sequentially arranged on a glass substrate 1. It has a configuration. These cells are connected in series.

  FIG. 2 is a cross-sectional perspective view showing the cell structure of the dye-sensitized solar cell C according to this embodiment. As shown in this figure, the dye-sensitized solar cell C according to this embodiment includes a substrate 1 having light transmittance, a transparent conductive layer 3 formed on the substrate 1, a photoelectrode 7, and a separator layer. 15 and a counter electrode 13 provided with respect to the photoelectrode 7 via a separator layer 15. The photoelectrode 7 includes an n-type semiconductor layer 9 stacked on the transparent conductive layer 3 and a dye 11 that emits electrons when received by the n-type semiconductor layer 9. In the photoelectrode 7, the counter electrode 13, and the separator layer 15, an electrolytic solution 17 that can transport charges such as an electrolytic solution or an ionic liquid is immersed. Furthermore, the dye-sensitized solar cell C according to the present embodiment includes a connection portion 21 that connects the counter electrode 13 and the transparent conductive layer 3. When this dye-sensitized solar cell C is irradiated with light from the photoelectrode 7 side, the dye 11 absorbs light and generates electrons and holes. The holes move from the dye 11 to the electrolytic solution 17 and oxidize ions in the electrolytic solution 17. On the other hand, the electrons move from the photoelectrode 7 to the counter electrode 13 via the transparent conductive layer 3 and the connecting portion 21, and reduce ions in the electrolytic solution 17 there. An electromotive force is generated by the oxidation-reduction potential of the ion species, and the power generation action of the battery is obtained. Below, the detail of each part of the dye-sensitized solar cell C which concerns on this embodiment is demonstrated.

  As the substrate 1, a substrate having optical transparency is used. What is used for a silicon solar cell or a liquid crystal display panel can be used, and specifically, a transparent glass substrate can be used suitably.

  The transparent conductive layer 3 is formed on the substrate 1 having optical transparency. The transparent conductive layer 3 can be formed, for example, by depositing tin oxide on the substrate 1. In particular, if a metal oxide such as tin oxide (FTO) doped with fluorine is used, a suitable transparent conductive layer 3 can be formed. The transparent conductive layer 3 has a scribe 5, and the two transparent conductive layers 3 are separately formed with an interval corresponding to the width of the scribe 5.

  The photoelectrode 7 has a dye 11 and an n-type semiconductor layer 9 which are stacked on one of the two transparent conductive layers 3 formed separately and emit electrons upon receiving light. As the n-type semiconductor, a metal oxide semiconductor is suitable. For example, oxides such as titanium, zinc, tin, indium, and zirconium are preferably used. A good porous n-type semiconductor layer 9 can be formed by thinning these semiconductor materials into a microcrystalline or polycrystalline state. In particular, the porous titanium oxide layer is suitable as the n-type semiconductor layer 9 included in the photoelectrode 7. The dye 11 emits electrons upon receiving light. As such a pigment | dye 11, the pigment | dye which has absorption in visible region or an infrared region is suitable, For example, a metal complex and an organic pigment | dye can be used. In particular, it is preferable to use a ruthenium complex. The dye 11 is attached to the surface of the porous n-type semiconductor layer 9. Adhesion can be performed by chemical adsorption, physical adsorption, or the like. Specifically, there is a method of immersing the porous n-type semiconductor layer 9 in a solution containing the dye 11.

  The separator layer 15 is laminated on the photoelectrode 7 and has an L-shaped cross section so as to cover one side of the photoelectrode 7. One end of the separator layer 15 is in contact with the scribe 5 on the substrate 1. As a result, direct contact between the photoelectrode 7 and the counter electrode 13 and direct contact between the photoelectrode 7 and the connecting portion 21 are avoided. The separator layer 15 is formed to be porous using, for example, rutile-type titanium oxide, and stores the electrolytic solution 17 inside the pores. That is, the electrolytic solution layer of the present invention is formed by the electrolytic solution 17 stored in the separator layer 15.

  The counter electrode 13 is opposed to the photoelectrode 7 with a predetermined interval. The photoelectrode 7 and the counter electrode 13 are formed in an equal area. As the counter electrode 13, porous carbon having conductivity and durability against the electrolytic solution 17 is preferably used. The counter electrode 13 composed of such a porous carbon layer sucks the electrolytic solution 17 into the inside thereof, and also functions as a catalyst for the reduction reaction of ions in the electrolytic solution 17.

The connection portion 21 is a member that is provided across the counter electrode 13 and the transparent conductive layer 3 and connects them. The connection portion 21 is formed using a material that has conductivity and does not have a function as a reduction catalyst. As such a material, conductive oxides such as indium / tin oxide, antimony / tin oxide, fluorine-doped tin oxide, and conductive zinc oxide are preferably used. These may be used alone or in combination of any two or more. As shown in FIG. 2, the connecting portion 21 contacts the one end face of the separator layer 15 from the transparent conductive layer 3 adjacent to the transparent conductive layer 3 on which the photoelectrode 7 is laminated and the scribe 5, while contacting the one end face of the separator layer 15. It extends vertically. Then, the transparent conductive layer 3 and the counter electrode 13 are made conductive by being in contact with the counter electrode 13 on the upper side surface thereof.
In the cell structure of the conventional dye-sensitized solar cell C in FIG. 6, the position where the connecting portion 21 is disposed covers one side of the photoelectrode 103 without facing the photoelectrode 103 in the counter electrode 104. This corresponds to the position (104a) occupied by the part. Since the connection portion 21 in the present invention has conductivity and does not have a function as a reduction catalyst, only the reduction reaction is performed in the connection portion 21 while ensuring an appropriate flow of generated electrons. It can suppress that it advances selectively. Since the photoelectrode 7 and the counter electrode 13 are formed in an equal area, the progress of the reduction reaction and the oxidation reaction of the ions in the electrolytic solution 17 are almost equal, and the bias of the redox cycle is prevented. The Accordingly, only the reduction reaction proceeds selectively at a part of the counter electrode 13 to generate a redox pair concentration gradient, and the amount of active ionic species decreases as the use continues and the conductivity of the electrolytic solution 17 decreases. The occurrence of inconveniences such as lowering the output can be suppressed. Therefore, the dye-sensitized solar cell C excellent in long-term durability can be provided.

  The separator layer 15 is formed in an L-shaped cross section so as to cover one side of the photoelectrode 7, and the connecting portion 21 is in contact with one end face of the separator layer 15. The surface area of the counter electrode 13 is larger by the thickness of the separator layer 15 at the part covering one side (half width to about the full width of the scribe 5). However, since the width of the scribe 5 is usually extremely small with respect to the width of the photoelectrode 7 and the counter electrode 13 and the difference is negligible, it is treated here as having an equal area. That is, in the present invention, the “equal area” between the photoelectrode 7 and the counter electrode 13 means that the areas are substantially equal, and even if there is a slight difference in size, It is assumed that the difference between the degree of progress of the reduction reaction and the oxidation reaction of the ions is substantially included in the “equal area”.

  Here, the connecting portion 21 is preferably a sintered body made of a conductive oxide powder having a particle diameter of 1 to 50 nm as a raw material. If such a fine powder is used as a raw material to form the connection part 21 on the transparent conductive layer 3 by sintering, the transparent conductive layer 3 and the connection part 21 can be tightly bound. Therefore, the mechanical strength against external force and expansion / contraction stress at the binding site can be improved, and the long-term durability of the dye-sensitized solar cell C can be improved from this point.

  As described above, the dye-sensitized solar cell module M includes a first step of processing the substrate 1, a second step of forming the n-type semiconductor layer 9, a third step of forming the separator layer 15, and a connection portion. The fourth step of forming 21, the fifth step of forming the counter electrode 13, the sixth step of forming the photoelectrode 7 by adsorbing the dye 11 to the n-type semiconductor layer 9, the photoelectrode 7, the counter electrode 13 and the separator layer 15. It is manufactured through a seventh step of immersing the electrolytic solution 17. This manufacturing process will be specifically described below together with examples.

Example 1
The dye-sensitized solar cell C was manufactured by the process as shown in FIG. When performing the performance evaluation test, the transparent conductive layer 3 on which the photoelectrode 7 is laminated, the transparent conductive layer 3 adjacent to the scribe 5 and the counter electrode 13 have conductivity, and In order to confirm that the connection part 21 having no function as a reduction catalyst exhibits a function of suppressing performance degradation due to continuous operation purely, a structure having only one cell is used. It was.

  In the first step shown in FIG. 3A, the substrate 1 is processed. First, fluorine-doped tin oxide (FTO) was attached on a transparent glass substrate to form a transparent conductive layer 3 having a thickness of 0.5 μm. Thereafter, the transparent conductive layer 3 was subjected to YAG laser processing to form a scribe 5 having a width of 50 μm, and the adjacent transparent conductive layers 3 were insulated from each other.

  In the second step shown in FIG. 3B, the n-type semiconductor layer 9 is formed. After dispersing titanium oxide having an average particle size of 25 nm or less and mixing a cellulose-based binder, mixing was performed while substituting with a solvent such as butyl carbitol, and a paste was prepared so that the titanium oxide solid content concentration was finally 16 wt%. . This paste was laminated on the transparent conductive layer 3 by screen printing, then dried and baked at 450 degrees. In this way, an n-type semiconductor layer 9 made of a titanium oxide layer was formed.

In the third step shown in FIG. 3C, the separator layer 15 is formed. Rutile 100% titanium oxide having an average particle size larger than 250 nm and zirconium oxide having an average particle size of 20 nm were dispersed, and a cellulose binder was mixed. Thereafter, mixing was performed while substituting with a solvent such as butyl carbitol, and a paste was prepared so that the final solid content of titanium oxide and zirconium oxide was 15 wt%. This paste was laminated on the photoelectrode 7 by screen printing, then dried and baked at 450 degrees. In this way, a separator layer 15 having an average film thickness of 5 μm was formed.
The separator layer 15 is formed in an L-shaped cross section so that one end thereof is in contact with the scribe 5 on the substrate 1 and covers one side of the light electrode 7. As a result, direct contact between the photoelectrode 7 and the counter electrode 13 and direct contact between the photoelectrode 7 and the connecting portion 21 are avoided.

In the fourth step shown in FIG. 3D, the connection portion 21 is formed. Disperse nanoparticle powder of indium tin oxide (ITO) with an average particle diameter of 1 to 50 nm, mix with cellulose binder, mix with solvent replacement such as butyl carbitol, and finally the ITO solid content concentration The paste was prepared so as to be 16 wt%. This paste was laminated by screen printing on the transparent conductive layer 3 adjacent to the transparent conductive layer 3 on which the photoelectrode 7 was laminated and the scribe 5, and then dried and baked at 450 degrees. Thus, the connection part 21 was formed.
The connecting portion 21 is formed to be slightly higher than the upper surface of the separator layer 15 by adjusting the raw material concentration.

In the fifth step shown in FIG. 3E, the counter electrode 13 is formed. Carbon black having a specific surface area of 800 m ² / g or more, graphite having an average particle diameter of 5 μm, and titanium oxide having an average primary particle diameter of 6 nm were mixed at a weight ratio of 1: 5: 1, and further a cellulosic binder was further mixed. Thereafter, the mixture was mixed while substituting with a solvent such as butyl carbitol, and finally the paste was prepared so that the solid content concentration was 30 wt%. This paste was laminated on the separator layer 15 by screen printing so as to fill the step between the connection portion 21 and the separator layer 15, dried, and fired at 450 degrees. In this way, the counter electrode 13 was formed.

  In the sixth step, the dye 11 is adsorbed on the n-type semiconductor layer 9. The substrate 1 that has undergone the first to fifth steps is immersed in an ethanol solution of a ruthenium complex for a predetermined time (24 hours), thereby adsorbing the dye 11, that is, the ruthenium complex, to the n-type semiconductor layer 9 made of a titanium oxide layer. I let you. In this way, the photoelectrode 7 having the n-type semiconductor layer 9 containing the dye 11 was formed.

In the seventh step, the electrolytic solution 17 is immersed in the photoelectrode 7, the counter electrode 13, and the separator layer 15. In this example, 0.05 mol / L iodine (I ₂ ), 0.5 mol / L lithium iodine (LiI), and 0.5 mol / L 4-t-butylpyridine were added to 3-methoxypropionitrile. The dissolved electrolyte solution was injected as an electrolyte solution 17 and sealed in the cell. In this way, a dye-sensitized solar cell C was manufactured.

Two dye-sensitized solar cells C thus obtained were prepared and evaluated for each of initial output, continuous operation durability, performance recovery, and temperature cycle durability.
For the initial output, the initial conversion efficiency (A) was measured under a condition of 100 mW / cm ² with a solar simulator using a xenon lamp with an AM 1.5 spectral distribution.
For continuous operation durability performance, one of the dye-sensitized solar cells C produced two by two has an operation durability equipped with a xenon light source capable of irradiating AM1.5 spectral distribution while maintaining the ambient temperature at 60 ° C. The conversion efficiency (B) after continuous operation was measured after installing the tester, connecting the both-end outputs of the battery with conducting wires, and leaving it to stand for 1000 hours while irradiating light of 100 mW / cm ² .
Regarding performance recovery, the battery was then allowed to stand in the dark at room temperature for 24 hours, and the conversion efficiency (C0) was measured after resting in the dark. And the ratio of the conversion efficiency after dark stop (C0) with respect to the conversion efficiency after continuous operation (B) was calculated | required as a recovery rate (C).
For temperature cycle durability, another one of the two dye-sensitized solar cells C produced was used, and a temperature cycle test from −40 ° C. to 90 ° C. was performed 100 cycles, and the conversion efficiency after temperature cycle ( D0) was measured. And the ratio of the conversion efficiency after temperature cycle (D0) with respect to the initial conversion efficiency (A) was calculated | required as a performance maintenance factor (D).

(Example 2)
A dye-sensitized solar cell was formed under the same conditions as in Example 1 except that the connecting portion 21 of Example 1 was formed using an antimony tin oxide (ATO) nanoparticle powder having an average particle diameter of 50 nm or less. C was produced and evaluated in the same manner as in Example 1.

  As a common comparative example of Example 1 and Example 2, the same evaluation as described above was performed using a conventional dye-sensitized solar cell C as shown in FIG. The results are shown in Table 1.

According to Table 1, in the cell of Example 1 (No. 1) and the cell of Example 2 (No. 3), the conversion efficiency (B) after continuous operation is almost the same as the initial conversion efficiency (A). Not done. On the other hand, in the cell (No. 5) of the comparative example, the conversion efficiency was lowered by 1000 hours of continuous operation. From this, it was confirmed that the continuous operation durability of the cell can be improved by providing the connection portion 21 formed using a conductive oxide. This is because the connection part 21 does not have a function as a reduction catalyst, so that the amount of active ionic species decreases as the use continues, and the occurrence of inconveniences such as a decrease in the conductivity of the electrolytic solution 17 is suppressed. It is thought to be from.
Regarding the temperature cycle durability, in the cell of Example 1 (No. 2) and the cell of Example 2 (No. 4), the conversion efficiency after temperature cycle (D0) is compared with the initial conversion efficiency (A). There is almost no change. On the other hand, in the cell (No. 6) of the comparative example, the conversion efficiency was lowered by the temperature cycle (100 cycles) from −40 ° C. to 90 ° C. From this, it was confirmed that the temperature cycle durability of the cell can be improved by providing the connection portion 21 formed using a conductive oxide. This is because the conductive oxide forming the connection portion 21 is more tightly bound to the transparent conductive layer 3 than the porous carbon forming the counter electrode 13, and swelling due to the electrolytic solution 17 is suppressed. For this reason, it is considered that adhesion is guaranteed over a long period against expansion and contraction stress caused by repeated freezing and thawing of the electrolytic solution 17.

(Example 3)
A dye-sensitized solar cell C was produced under the same conditions as in Example 1 except that the electrolytic solution 17 of Example 1 was changed to an electrolytic solution made of an ionic liquid. As an electrolytic solution composed of an ionic liquid, 0.5 mol of iodine (I ₂ ) and 0.5 mol of 4-t-butylpyridine were dissolved in 5 mol of 1-propyl-3-methylimidazolium iodide (MPII). Things were used. Its viscosity was about 900 mPa · s. An electrolytic solution made of this ionic liquid was injected into the cell and sealed. In this way, a dye-sensitized solar cell C was manufactured.

  Two dye-sensitized solar cells C thus obtained were produced and evaluated in the same manner as in Example 1 and Example 2. As a comparative example, the same evaluation as described above was performed using a conventional dye-sensitized solar cell C as shown in FIG. 6 in which an electrolytic solution made of an ionic liquid was sealed. The results are shown in Table 2.

According to Table 2, in the cell of Example 3 (No. 7), the conversion efficiency (B) after continuous operation hardly changes compared to the initial conversion efficiency (A). On the other hand, in the cell (No. 9) of the comparative example, the conversion efficiency was greatly reduced by continuous operation for 1000 hours. From this, it was confirmed that the continuous operation durability of the cell can be significantly improved by providing the connection portion 21 formed using a conductive oxide. This is because the connection portion 21 does not have a function as a reduction catalyst, similarly to the consideration in the first and second embodiments. Therefore, the amount of active ionic species decreases as the use continues, and the electrolytic solution 17 This is thought to be because the occurrence of inconveniences such as a decrease in the electrical conductivity is suppressed. In particular, when a highly viscous electrolytic solution 17 such as an electrolytic solution made of an ionic liquid is used, the fluidity of the electrolytic solution 17 itself is low, so that once the concentration gradient of the redox pair occurs, the original state is restored. Since it takes a very long time, the effect becomes more prominent.
Further, regarding the temperature cycle durability, in the cell (No. 8) of Example 3, the post-temperature cycle conversion efficiency (D0) hardly changes compared to the initial conversion efficiency (A). On the other hand, in the cell (No. 10) of the comparative example, the conversion efficiency was greatly reduced by the temperature cycle (100 cycles) from −40 ° C. to 90 ° C. From this, it was confirmed that the temperature cycle durability of the cell can be greatly improved by providing the connection portion 21 formed using the conductive oxide also in this example.

[Reference example]
Reference examples of the present invention will be described with reference to the drawings.
FIG. 4 is a cross-sectional perspective view showing the cell structure of the dye-sensitized solar cell C according to this embodiment. The basic structure is the same as that of the dye-sensitized solar cell C according to the first embodiment. However, in this reference example, the material forming the connection portion 21 is different, and the manufacturing method is partially different accordingly. Below, it demonstrates centering on difference with 1st embodiment.

  In the present reference example, the connection portion 21 is formed integrally with the counter electrode 13 using the same material as that for forming the counter electrode 13. That is, using the porous carbon having conductivity and durability against the electrolytic solution 17, the counter electrode 13 and the connection portion 21 are integrated and formed in an L-shaped cross section so as to cover one side of the photoelectrode 7. .

  And the resin material 31 is impregnated with respect to the connection part 21 of them. As the resin material 31, a thermoplastic resin, a thermosetting resin, an ultraviolet curable resin, a photocurable resin, or the like can be used. In particular, for example, if a material mainly composed of a polyolefin-based thermoplastic resin such as polyethylene, polypropylene, polyisobutylene, etc. is used, it is easy to heat it up to the vicinity of the melting point and apply it to the surface of the connecting portion 21. This is preferable because it can be impregnated into the pores 33.

FIG. 5 is an enlarged view of the connecting portion 21. The counter electrode 13 and the connection portion 21 are formed of a porous carbon layer, and these have pores 33 therein. As for the counter electrode 13, as usual, the electrolytic solution 17 is immersed in the pores 33, and carbon functions as a catalyst on the surface of the pores 33, whereby the reduction reaction of ions in the electrolytic solution 17 proceeds.
On the other hand, a resin material 31 mainly composed of a thermoplastic resin is melted and applied to the connection portion 21 from the outside. The applied resin material 31 is impregnated into the inside of the connection portion 21, and the pores 33 as a field for the reduction reaction of ions in the electrolytic solution 17 are filled with the resin material 31. For this reason, the function of carbon as a catalyst on the surface of the pore 33 is hindered, and the reduction reaction hardly proceeds in the pore 33 inside the connection portion 21. Therefore, only the reduction reaction proceeds selectively, and as the use continues, the amount of active ionic species decreases, the conductivity of the electrolytic solution 17 decreases, and it is possible to suppress inconveniences such as a decrease in output. Is done. Therefore, the dye-sensitized solar cell C excellent in long-term durability can be provided.

  The present invention can be suitably used for dye-sensitized solar cells and dye-sensitized solar cell modules.

The perspective view which shows the whole structure of the dye-sensitized solar cell module which concerns on this invention Sectional perspective view which shows the cell structure of the dye-sensitized solar cell which concerns on 1st embodiment Manufacturing process diagram of the dye-sensitized solar cell module according to the first embodiment Sectional perspective view showing cell structure of dye-sensitized solar cell according to Reference Example Enlarged view of the connection part of the dye-sensitized solar cell according to the reference example Sectional perspective view showing the cell structure of a conventional dye-sensitized solar cell

C Dye-sensitized solar cell M Dye-sensitized solar cell module 1 Substrate 3 Transparent conductive layer 7 Photoelectrode 9 N-type semiconductor layer 11 Dye 13 Counter electrode 17 Electrolytic solution 21 Connection portion 31 Resin material

Claims (3)

Two transparent conductive layers separately formed at a predetermined interval on a single substrate having optical transparency,
A photoelectrode having an n-type semiconductor layer, which is laminated on one of the transparent conductive layers, and contains a dye that emits electrons upon receiving light;
A separator layer as an electrolyte layer that is laminated on the photoelectrode and in which an electrolyte is stored;
In the dye-sensitized solar cell provided on the separator layer and provided with a counter electrode containing carbon particles,
Provided across the other of the transparent conductive layer and the counter electrode, extending perpendicularly to the substrate while in contact with one end surface of the separator layer, and provided with a connection portion in contact with the counter electrode on its side surface,
The connecting portion is made of a sintered body having conductivity and a conductive oxide powder having a particle diameter of 1 to 50 nm as a raw material ,
The conductive oxide powder is composed of at least one selected from indium / tin oxide, antimony / tin oxide, fluorine-doped tin oxide, and conductive zinc oxide. Solar cell. The connection part is formed by laminating and baking a paste containing the conductive oxide powder by screen printing after forming the separator layer,
The counter electrode is formed by laminating a paste containing carbon particles and oxide particles having binding properties so as to fill a step between the connection portion and the separator layer after the formation of the connection portion, and firing the paste. The dye-sensitized solar cell according to claim 1, which is formed by: A dye-sensitized solar cell module in which a plurality of dye-sensitized solar cells according to claim 1 or 2 are used and connected in series.

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