JP5240650B2 - 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.
Liquid adhesives include silicon resins, epoxy resins, acrylic resins, etc. All of these adhesives have a certain degree of polarity in order to improve the adhesiveness with the adhesive such as the 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, a 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.
Further, in this type of method, the four corners of the photoelectrode 104 and the counter electrode 107 are clamped and held by the four bolts 111 and nuts 112, so that the pressure applied to the gasket 109 tends to be uneven. Since local high-pressure parts and low-pressure parts are likely to occur locally, problems such as breakage of the substrate due to stress concentration, loss of elastic body due to high compression, and leakage due to insufficient surface pressure due to under-compression are caused. It was.

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 an elastic gasket and an adhesive layer in parallel, it is possible to use an adhesive with the optimum polarity for bonding and integrating the photoelectrode and the counter electrode, and also due to temperature changes. Even if peeling of the bonded portion or damage to the substrate occurs due to swelling and shrinkage, the electrolyte can be prevented from leaking, and a uniform surface pressure can be applied to the gasket to exhibit a good sealing function.

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 is located on the outer peripheral side of the gasket, the gasket made of an elastic material sealing the electrolyte layer , and the counter electrode and the photoelectrode is more structure and the adhesive layer are bonded and integrated, the gasket Together are arranged between the groove respectively provided on the counter electrode and the photoelectrode, the material of the gasket, an ethylene propylene terpolymer (EPDM), adhesive liquid epoxy resin used in the adhesive layer It is characterized by being.

The present invention has the following effects.
According to the dye-sensitized solar cell of the first aspect of the invention, the optimum polarity for bonding and integrating the photoelectrode and the counter electrode by using the elastic material gasket and the adhesive layer in parallel. It is possible to use an adhesive with an adhesive, and even if the adhesive part is peeled off or the substrate is damaged due to swelling shrinkage due to temperature change, the electrolyte can be prevented from leaking and the gasket has a uniform surface pressure. It is easy to assemble because the gasket is easy to position, and it can seal directly between the electrode base materials, so it can exhibit a good sealing function, and electrolyte The layer is not easily eroded or swollen by the layer, exhibits a stable sealing function over a long period of time, and can securely bond and integrate the photoelectrode and the counter electrode.

Furthermore, according to the dye-sensitized solar cell of the invention described in claim 2 , high conversion efficiency can be expected.

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, an elastic gasket 9 is arranged between the groove portions 41 and 71 provided in the photoelectrode 4 and the counter electrode 7 respectively.
Furthermore, an adhesive layer 10 in which the photoelectrode 4 and the counter electrode 7 are bonded and integrated is present on the outer peripheral side of the gasket 9.

The material used for the gasket 9 is a synthetic rubber or synthetic resin having elasticity, but ethylene propylene terpolymer (EPDM) is particularly suitable.
Examples of the material used for the adhesive layer 10 include silicon-based resins, epoxy resins, and acrylic resins that are liquid adhesives.
Each of the adhesives has a certain degree of polarity in order to enhance the adhesiveness with the adhesive such as the substrate, but the adhesive layer 10 does not come into direct contact with the electrolyte layer 8, so that the electrolyte layer 8 No erosion or swelling due to
For this reason, a liquid epoxy resin is used suitably.

  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. in a solvent, lithium iodide, or a liquid-solid electrolyte obtained by adding iodine, can be preferably used quasi body of electrolyte polymer gel electrolyte or the like.
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.

Further, sensitizing dyes which form semiconductor 3 is, as Le ruthenium complex dye may be used ruthenium-bipyridine complex having a carboxyl group, bipyridyl-based, phenanthroline, quinoline and the like.

The material used for forming the first conductive film 2, tin-doped indium oxide having high conductivity is excellent in transparency (ITO) or fluorine-doped tin oxide (FTO), a combination of a plurality of gold, platinum and their A thing can be formed by appropriate methods, such as a vacuum evaporation method, a sputtering evaporation method, and 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.

Example A titania layer was formed by applying titania particles in a paste form to a glass substrate (150 mm × 150 mm thickness 2 mm) provided with a transparent conductive film in a paste form of 120 mm × 120 mm thickness 10 μm and sintering.
The titania layer thus formed was loaded with a ruthenium bipyridyl complex having a carboxyl group (N719) to form a photoelectrode.
On the other hand, platinum was deposited in the range of 120 mm x 120 mm as a counter electrode on a transparent conductive film on a glass substrate (150 mm x 150 mm thickness 2 mm).
The photoelectrode and the counter electrode were each formed with a rectangular groove 125 mm long × 125 mm wide, 1.5 mm wide and 0.5 mm deep, and an EPDM gasket 125 mm long × 125 mm wide and 1.3 mm in diameter was attached to the groove.
After applying the adhesive to the outer periphery of the photoelectrode and counter electrode with a width of 10 mm, the photoelectrode and counter electrode are bonded together, and the adhesive is applied with a weight of 100 μm between the electrodes and a weight applied evenly. Cured.
After the adhesive was cured, an electrolyte solvent in which iodine, lithium iodide and 1,2 dimethyl-3-propylimidazolium iodide were dissolved in acetonitrile was sealed between the electrodes to fabricate a dye-sensitized solar cell.

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 Gasket 10 Adhesive layer 41 Groove part 71 Groove part

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). An elastic material gasket (9) sandwiched between the counter electrode (7) and sealing the electrolyte layer (8), and located on the outer peripheral side of the gasket (9), the photoelectrode ( 4) and an adhesive layer (10) in which the counter electrode (7) is bonded and integrated, and the gasket (9) is provided on the photoelectrode (4) and the counter electrode (7), respectively. The gasket (9) is made of ethylene propylene terpolymer (EPDM), and the adhesive used for the adhesive layer (10) is disposed between the groove portions (41) and (71). A dye-sensitized solar cell, which is a liquid epoxy resin . The dye-sensitized solar cell according to claim 1, wherein a gap between the photoelectrode (4) and the counter electrode (7) is 150 µm or less .

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