JP5246541B2 - Dye-sensitized solar cell - Google Patents

Description

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

In recent years, there is concern about deterioration of the global environment such as global warming, and solar power generation has attracted attention as clean energy.
However, its spread is not yet satisfactory.
And one of the biggest causes that are the obstacle to the spread is the high manufacturing cost of silicon solar cells which are currently mainstream.
A major factor that does not reduce the manufacturing cost is that there is a limit in the manufacturing method for supplying a large amount of silicon semiconductors necessary for silicon-based solar cells at a low cost, and it is unlikely that significant improvement will be expected in the future.

In contrast to this silicon-based solar cell, a dye-sensitized solar cell announced by the group of Gretzel et al. Is a wet solar cell using a light conversion layer sensitized by a spectral sensitizing dye as a working electrode.
The basic structure of this wet solar cell includes a transparent conductive electrode provided on a transparent substrate such as glass, an electrolyte, a porous semiconductor layer such as spectral sensitizing dye, titanium oxide, and a counter electrode provided on the substrate.
This type of dye-sensitized solar cell is expected to be a low-cost solar cell because the material used is inexpensive and does not require large-scale equipment such as a vacuum process required for silicon-based solar cells. Collecting.

However, the reliability of the dye-sensitized solar cell developed so far is lower than that of silicon.
One of the causes is a problem of sealing an electrolyte that is an electron carrier.
If the electrolyte leaks or moisture enters the electrolyte from the outside, not only will the power generation efficiency decrease, but also the light conversion layer will deteriorate, causing problems that shorten the life of the dye-sensitized solar cell. .
Electrolytes include forms such as liquids, gels and solids.
A gel or solid with little leakage is suitable for sealing the electrolytic solution (Patent Document 1).
However, in order to obtain conversion efficiency as high as that of silicon, a liquid, or an organic solvent having high polarity and high volatility such as acetonitrile is preferable.
However, it is difficult to seal such an electrolyte in a solar cell.
Therefore, in order to improve the long-term reliability of the dye-sensitized solar cell, the electrolyte solution between the transparent conductive electrode and the counter electrode substrate is sealed around the edge of the substrate by using a sealing material. It is indispensable to prevent leakage and moisture intrusion.

As a sealing method studied so far, there is an adhesion method using a liquid adhesive (Patent Document 2), a hot melt film (Patent Document 3), a glass frit (Patent Document 4), and the like.
Examples of liquid adhesives include silicon-based resins, epoxy resins, acrylic resins, etc. All of these adhesives have a certain degree of polarity in order to improve the adhesiveness to an adhesive such as a substrate. ing.
For this reason, this polarity increases the affinity with the electrolytic solution, and the sealing performance deteriorates in the long term due to erosion and swelling.
On the other hand, polyisobutylene resin has been reported as an adhesive having a small polarity.
Thereby, although erosion and swelling by the electrolytic solution are suppressed to some extent, since the adhesiveness is inferior, the sealing performance may be deteriorated due to peeling or the like in the long term.

The hot melt film includes a thermoplastic resin having a carboxylic acid group in the molecular chain, specifically, Himiran (manufactured by Mitsui DuPont Chemical) (Patent Document 5).
However, since the liquid adhesive has polarity, the sealing performance may be deteriorated in the long term.
On the other hand, sealing with glass frit is excellent in sealing performance, but generally requires heat treatment at 450 ° C. or higher, which may cause deterioration of components such as a sensitizing dye.
In addition, the work becomes complicated and the manufacturing cost is deteriorated.
On the other hand, by using a silicate such as water glass, the solidification temperature can be set to 60 ° C. or lower.
However, water and sodium contained in the water glass may be dissolved in the electrolyte to lower the conversion efficiency (Patent Document 7).
In addition, since the cell temperature of solar cells rises due to the irradiation of sunlight, in any bonding method, when the linear expansion coefficient of the sealing material and the substrate is different, the adhesive portion is peeled off or the substrate There was a risk of damage.

For such a sealing problem of the adhesion method, as shown in FIG. 2, a synthetic resin having elasticity is used as the sealing material, and this is arranged around the edge of the substrate, and is sandwiched and compressed by the substrate. A non-adhesive method for sealing an electrolytic solution has been proposed (Patent Document 6).

That is, the photoelectrode 104 is made of a transparent first electrode substrate 101, a first conductive film 102 provided on one surface of the first electrode substrate 101, and a semiconductor material on the first conductive film 102. The porous semiconductor layer 103 is formed and formed by adsorbing a sensitizing dye.
The counter electrode 107 includes a second electrode base material 105 and a second conductive film 106 provided on one surface of the second electrode base material 105.
An electrolyte layer 108 containing a liquid or gel electrolyte is interposed between the photoelectrode 104 and the counter electrode 107.
Further, a sealing material for sealing the electrolyte layer 108 is provided between the photoelectrode 104 and the counter electrode 107, and a synthetic resin material gasket 109 having elasticity is used as the sealing material. .
In order to integrate these members, the four corners of the photoelectrode 104 and the counter electrode 107 are clamped and held by four bolts 111 and nuts 112.

According to this method, since the sealing material has elasticity, it is possible to follow the swelling and shrinkage of the base material. Can be secured.
However, since the shape of the proposed sealing material is an O-ring shape, the space between the substrates becomes large, and it is very difficult to reduce the space thickness to 100 μm or less, which is a general space thickness in the bonding method. .
For this reason, even if it is excellent in sealing performance, high conversion efficiency cannot be expected.

Further, in order to compress and seal an O-ring shaped elastic body, generally a large seal surface pressure is required.
For this reason, when the area of the cell is increased, the substrate may be bent by a large compressive force or may be damaged in some cases.
Furthermore, there is no inexpensive material having both electrolytic solution resistance and low humidity permeability as the material of the O-ring.
For this reason, if a material that is highly resistant to the electrolyte solution is selected, it is not possible to sufficiently prevent the entry of water vapor from the outside, and if a material with good low-humidity permeability is selected, a problem of swelling due to the electrolyte solution is caused. .

JP 2002-299665 A JP 2002-368236 A JP 2003-188394 A JP 2004-172048 A JP 2007-335197 A JP 2006-202681 A JP 2007-074031 A

By using in parallel a first gasket made of a material having resistance to electrolytic solution and a second gasket made of a material having low humidity permeability, the resistance to electrolytic solution and low humidity It is an object to provide an inexpensive sealing means having transparency.

In order to achieve the above object, in the present invention, a transparent first electrode base material, a first conductive film provided on one surface of the first electrode base material, and a semiconductor material on the first conductive film A photoelectrode comprising a porous semiconductor layer formed by adsorbing a sensitizing dye, a second electrode substrate, a second conductive film provided on one surface of the second electrode substrate, A dye provided with a counter electrode comprising: an electrolyte layer disposed between the photoelectrode and the counter electrode; and a sealing means for sealing the electrolyte layer between the photoelectrode and the counter electrode In the sensitized solar cell, the sealing means is sandwiched between the photoelectrode and the counter electrode, and a first gasket made of an elastic material sealing the electrolyte layer, and the first gasket more becomes second gasket made of elastic material which is disposed on the outer peripheral side of said first gasket, the electrolyte solution The second gasket is made of an isobutyl rubber material having low humidity permeability, and the first gasket and the second gasket are lips. It is characterized by having a shape.

The present invention has the following effects.
According to the dye-sensitized solar cell of the first aspect of the present invention, the first gasket made of a material having resistance to electrolytic solution and the second gasket made of a material having low humidity permeability. By using gaskets in parallel, it is possible to provide an inexpensive sealing means that has both electrolytic solution resistance and low humidity permeability, and the gasket is less susceptible to erosion and swelling due to the electrolyte layer. As a result, it is possible to maintain the performance of a stable dye-sensitized solar cell over a long period of time and effectively prevent the intrusion of water vapor, and the substrate bends even when the cell area is increased. There is no fear of damage or damage.

Furthermore, according to the dye-sensitized solar cell of the invention described in claim 2, the assembly is easy.

Hereinafter, the best mode for carrying out the present invention will be described.
The best mode for carrying out the invention will be described with reference to FIG.

That is, the photoelectrode 4 is made of a transparent first electrode substrate 1, a first conductive film 2 provided on one surface of the first electrode substrate 1, and a semiconductor material on the first conductive film 2. The porous semiconductor layer 3 is formed and adsorbed with a sensitizing dye.
The counter electrode 7 includes a second electrode substrate 5 and a second conductive film 6 provided on one surface of the second electrode substrate 5.
An electrolyte layer 8 including a liquid or gel electrolyte is interposed between the photoelectrode 4 and the counter electrode 7.
Further, as sealing means, a first gasket 9 made of an elastic material sandwiched between the photoelectrode 4 and the counter electrode 7 and sealing the electrolyte layer 8, and on the outer peripheral side of the first gasket 9 A second gasket 10 made of an elastic material is arranged.

The material used for the first gasket 9 is a synthetic rubber or a synthetic resin having elasticity and resistance to electrolytic solution, but olefin rubber and fluororubber are preferably used, and in particular, ethylene propylene terpolymer (EPDM). Is preferred.
The material used for the second gasket 10 is a synthetic rubber or a synthetic resin having elasticity and moisture permeability, but butyl rubber or chloroprene rubber is preferably used, and isobutyl rubber is particularly preferable. is there.
The first gasket 9 and the second gasket 10 include lips 92 and 102 extending from the bases 91 and 101 toward the tip.
The bases 91 and 101 are bonded and fixed to the counter electrode 7 side.
Examples of the adhesive used here include silicon-based resins, epoxy resins, and acrylic resins that are liquid adhesives.
The lips 92 and 102 are in sealing contact with the photoelectrode 4.
In order to integrate these members, four corners of the photoelectrode 4 and the counter electrode 7 are clamped and held by four bolts 111 and nuts 112.

The material used for the first electrode substrate 1 is not particularly limited as long as it is transparent, but is glass, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyethersulfone, or the like, which is transparent or highly transparent. Moreover, what has the intensity | strength of the grade which pinches | interposes a sealing material can be used, You may use them individually, or may form and apply a mixture and a laminate using multiple.

Further, the second electrode substrate 5 is particularly limited as long as it can form a surface having smoothness enough to form the second conductive film 6 and has a strength enough to sandwich the sealing material. Any material such as an inorganic material, an organic material, or a metal material can be used.

The electrolyte layer 8 can be used without any particular limitation as long as it contains a liquid or gel electrolyte, but a mixed solution in which iodine and lithium iodide are dissolved in acetonitrile, methoxypropionitrile, or the like. A liquid electrolyte obtained by adding lithium iodide, iodine or the like to a solvent, or a pseudo-solid electrolyte such as a polymer gel electrolyte can be suitably used.
Further, in the case of a liquid, a normal temperature molten salt, specifically 1,2 dimethyl-3-propylimidazolium iodide, is used in order to lower the viscosity and smooth the diffusion of ions.

Furthermore, titanium oxide (TiO ₂ ) is preferable as the semiconductor material used for forming the porous semiconductor layer that forms the semiconductor layer 3, but is not limited thereto, SnO ₂ , ZnO, MgO, Al ₂ O ₃ or the like can be used.

As the sensitizing dye forming the semiconductor 3, a ruthenium bipyridine complex having a carboxyl group, bipyridyl, phenanthroline, quinoline, or the like can be used as a ruthenium complex dye.

Materials used for forming the first conductive film 2 are tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), gold, platinum, etc., which have excellent transparency and high conductivity, and combinations thereof. Can be formed by an appropriate method such as a vacuum deposition method, a sputter deposition method, or an ion plating method.

In addition, the second conductive film 6 may be formed by using platinum, carbon, or the like as long as it generates a potential difference with the first conductive film 2.

The present invention is not limited to the best mode for carrying out the invention described above, and various other configurations can be adopted without departing from the gist of the present invention.

It is sectional drawing which shows embodiment of the invention concerning a dye-sensitized solar cell. It is sectional drawing of the dye-sensitized solar cell concerning a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st electrode base material 2 1st electrically conductive film 3 Semiconductor layer 4 Photoelectrode 5 2nd electrode base material 6 2nd electrically conductive film 7 Counter electrode 8 Electrolyte layer 9 1st gasket 10 2nd gasket 91 Base 92 Lip 101 Base 102 Lip

Claims (2)

A transparent first electrode base material (1), a first conductive film (2) provided on one surface of the first electrode base material (1), and a semiconductor material on the first conductive film (2) A photoelectrode (4) comprising a porous semiconductor layer (3) formed by adsorbing a sensitizing dye, a second electrode substrate (5), and the second electrode substrate (5) A counter electrode (7) comprising a second conductive film (6) provided on one surface; an electrolyte layer (8) disposed between the photoelectrode (4) and the counter electrode (7); Photoelectrode (4
) And the counter electrode (7), a dye-sensitized solar cell provided with a sealing means for sealing the electrolyte layer (8), wherein the sealing means is the photoelectrode (4) and the counter electrode (7). A first gasket (9) made of an elastic material sandwiched between the counter electrode (7) and sealing the electrolyte layer (8), and disposed on the outer peripheral side of the first gasket (9) has been more becomes elastic member made of a second gasket (10), said first gasket (9) is ethylene-propylene terpolymer (EPDM) material manufactured with the electrolyte resistance, the second The gasket (10) is made of an isobutyl rubber material having low moisture permeability, and the first gasket (9) and the second gasket (10) have a lip shape. Dye-sensitized solar cell.   The first gasket (9) and the second gasket (10) are bonded and fixed to either the photoelectrode (4) or the counter electrode (7). Dye-sensitized solar cell.

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