JP2016119371A - Dye-sensitized solar cell and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dye-sensitized solar cell having a resin sealing structure excellent in heat resistance and mechanical strength, and a method for manufacturing the same.SOLUTION: A method for manufacturing a dye-sensitized solar cell comprises the steps of: preparing a first substrate 11 including a transparent conductive film 111, a second substrate 12, and a collector layer 15 made of metal and formed on the transparent conductive film 111; forming a resin coating film 16 around the collector layer 15; forming a thermoplastic resin layer 17 on at least one adhesive surface of the first substrate 11 and the second substrate 12; sticking the first substrate 11 and the second substrate 12 so as to secure the region into which a liquid electrolyte is encapsulated; and encapsulating a liquid electrolyte 14 between th first substrate 11 and the second substrate 12. At least one of the resin coating film 16 and the thermoplastic resin layer 17 includes a thermoplastic resin having a melting point lower than 80°C and a thermoplastic resin having a melting point higher than 80°C.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a dye-sensitized solar cell (hereinafter also referred to as “DSSC”) and a method for producing the same.

  In a dye-sensitized solar cell (hereinafter also referred to as “DSSC”), a metal oxide layer carrying a sensitizing dye is formed on a transparent conductive film of a translucent substrate on which a transparent conductive film is formed. The power generation electrode (negative electrode) produced in step 1 and the counter electrode (positive electrode) on which the catalyst metal is formed are opposed to each other. An electrolytic solution containing an electrolyte is included between the opposed electrodes. When the DSSC is irradiated with light, the dye adsorbed on the titanium oxide that is the metal oxide layer causes electronic excitation, the excited electrons are injected into the conduction band of the titanium oxide, and the electrons are transferred from the titanium oxide to the ITO that is a transparent conductive film. Or move to FTO and take out as current.

  DSSC generally employs glass as a substrate, but it has been devised to apply a film substrate in order to impart features such as light weight, thinness, and flexibility. Since the film substrate is flexible, the sealing agent needs to be flexible. In addition, the technology required to prevent electrolyte leakage from DSSC using a film substrate, such as ensuring adhesion and heat-resistant temperature, is higher than the sealing technology used for DSSC using a glass substrate. . Patent Document 1 describes an invention in which a photocurable resin or the like is used in DSSC using a plastic substrate.

JP 2010-138290 A

  The sealing resin used in Patent Document 1 contains an ultraviolet curing agent. The contained ultraviolet curing agent is basically consumed during the ultraviolet curing of the sealing resin. However, the ultraviolet curing agent in the sealing resin is not consumed 100%, and the unreacted ultraviolet curing resin and the ultraviolet curing agent remain in the cured sealing resin layer. Further, it has been confirmed by the present inventors that the uncured UV curable resin is eluted into the electrolyte together with the unreacted UV curable agent and the residue after the reaction of the UV curable agent. The excess ultraviolet curing agent eluted in the electrolytic solution and the residue after the reaction of the ultraviolet curing agent react with the redox (electrolyte) in the electrolytic solution, leading to inhibition of factors contributing to power generation.

  When using a thermoplastic resin instead of an ultraviolet curable resin, securing heat resistance and mechanical strength may be more problematic than using an ultraviolet curable resin. In view of such a situation, an object of the present invention is to provide a DSSC having a resin sealing structure excellent in heat resistance and mechanical strength without using an ultraviolet curable resin and a method for manufacturing the DSSC.

As a result of intensive studies by the inventor, the following invention has been completed.
According to the present invention, the steps of the method for producing a dye-sensitized solar cell include: a first substrate having an adhesive surface and having a transparent conductive film, a second substrate having an adhesive surface, and the transparent conductive film. A step of preparing a current collector layer made of metal formed on the substrate; a step of forming a resin coating film around the current collector layer; and heat applied to at least one adhesive surface of the first and second substrates A step of forming a plastic resin layer; a step of bonding the first and second substrates so as to secure a region in which the fluid electrolyte is sealed by facing each bonding surface; and before or after the bonding, Encapsulating a flowable electrolyte between the first and second substrates. According to the present invention, at least one of the resin coating film and the thermoplastic resin layer, preferably both, contains a thermoplastic resin having a melting point of less than 80 ° C. and a thermoplastic resin having a melting point of 80 ° C. or more. .
Preferably, both the thermoplastic resin having a melting point of less than 80 ° C. and the thermoplastic resin having a melting point of 80 ° C. or more are acid-modified polyolefins.
The dye-sensitized solar cell obtained by the production method of the present invention is also an embodiment of the present invention.

  In the present invention, at least two kinds of a thermoplastic resin having a low melting point and a thermoplastic resin having a high melting point are mixed. The mechanism for achieving both heat resistance and mechanical strength due to this is not necessarily clear, and the present invention is not limited to the following inferences. It can be considered that the heat resistance is improved by arranging a low melting point resin and causing an interaction as compared with the case of using only the low melting point resin. When a low-melting resin is disposed around a high-melting resin, when the resin is sealed, the resin partially melts by heating the low-melting resin and can be sealed. Since the low melting point resin is arranged around the high melting point resin, the high melting point resin is solvated into the low melting point resin and its crystallinity is lowered. It is presumed that the sealing performance of the material is improved.

It is a schematic cross section of an example of DSSC manufactured by this invention.

  The present invention will be described in detail with appropriate reference to the drawings. However, the present invention is not limited to the illustrated embodiment, and in the drawings, the characteristic portions of the invention may be emphasized and expressed, so that the accuracy of the scale is not necessarily guaranteed in each part of the drawings. Not.

  FIG. 1 is a schematic cross-sectional view of an example of a DSSC manufactured according to the present invention. FIG. 1A is an overall view, and FIG. 1B is an enlarged view near the current collector layer. The DSSC has a first substrate 11. The first substrate 11 has adhesive surfaces 11a and 11b. The first substrate 11 may have a laminated structure and includes at least a transparent conductive film 111. For example, the transparent conductive film 111 may be formed on the plastic plate 112, and in this embodiment, the plastic plate 112 and the transparent conductive film 111 constitute the first substrate 11.

  The DSSC has a second substrate 12. The second substrate 12 has adhesive surfaces 12a and 12b. In the form of FIG. 1, the second substrate 12 includes a metal plate 121 and a catalyst layer 122 formed on one surface thereof. The first and second substrates 11 and 12 correspond to a pair of electrodes facing each other. The first and second substrates 11 and 12 are typically plate-shaped, and there is no particular limitation on the form or material as long as the penetration of the electrolyte is prevented. As shown in the figure, one or both of the pair of substrates 11 and 12 may be a laminate composed of a plurality of layers or films. The substrate may be a hard substrate or a flexible substrate (so-called flexible substrate). In this DSSC, the first substrate 11 on which the dye-carrying oxide semiconductor layer 13 (for example, the dye-carrying titanium oxide layer) is formed functions as a negative electrode, and the second substrate 12 that faces the first substrate 11 functions as a positive electrode. A fluid electrolyte 14 is sealed between the laminate of the first substrate 11 and the dye-supported oxide semiconductor layer 13 and the second substrate 12.

  In DSSC, the electrolyte is generally used in the presence of some medium. The electrolyte itself is flowable, or the one in which the electrolyte coexists with a flowable medium is called a flowable electrolyte. As a form which can flow, forms, such as a liquid and a gel state, are not specifically limited, for example. For specific embodiments of the fluid electrolyte 14, reference can be made to the prior art in DSSC as appropriate.

  Non-limiting examples of the transparent conductive film 111 of the first substrate 11 include ITO and FTO. The dye-carrying oxide semiconductor layer 13 suitably provided adjacent to the transparent conductive film 111 acts as a power generation layer, and the material is a porous film made of titanium oxide or a porous film made of zinc oxide. These include, but are not limited to, dyes carried on these. For the material and configuration of the dye-carrying oxide semiconductor layer 13, known techniques can be referred to as appropriate. In the form of FIG. 1, the current collector layer 15 is formed on the transparent conductive film 111. The current collector layer 15 is made of a metal such as silver formed on the transparent conductive film 111.

  FIG. 1B is an enlarged cross-sectional view in the vicinity of the current collector layer 15. The current collector layer 15 formed on the transparent conductive film 111 is covered with the resin coating film 16. The resin coating film 16 is expected to effectively prevent the liquid material from entering from the vicinity of the interface between the current collector layer 15 and the transparent conductive film 111. For example, when the fluid electrolyte 14 is used in DSSC, the fluid electrolyte 14 is suppressed from reaching the vicinity of the interface between the current collector layer 15 and the transparent conductive film 111. Even if a substance that erodes the layer 15 is included, the erosion to the current collector layer 15 is effectively suppressed.

  The first substrate 11 and the second substrate 12 are bonded together via a thermoplastic resin layer 17. Specifically, the thermoplastic resin layer 17 is formed on at least one of the bonding surfaces 11a and 11b of the first substrate 11 and the bonding surfaces 12a and 12b of the second substrate 12, and the bonding surfaces are bonded to each other. At this time, the thickness or the like of the thermoplastic resin layer 17 is adjusted so as to secure a region in which the fluid electrolyte 14 is sealed between the first and second substrates 11 and 12.

  In the resin coating film 16 and the thermoplastic resin layer 17 described above, a thermoplastic resin having a property of being softened by heating and exhibiting plasticity and solidifying by cooling is preferably used. A polymer having a functional group exhibiting alkalinity in the side chain is preferably used. The basic skeleton of the thermoplastic resin is not particularly limited, and preferably includes a polyolefin skeleton, a polyoxyalkylene skeleton, a cellulose skeleton, a polyimide skeleton, and the like. Preferred examples of the functional group in the side chain include, but are not limited to, a carboxyl group, a phosphoric acid group, and a phosphonic acid group. The thermoplastic resin may be a modified resin or may not be modified. Specific resins include ionomer resins, polyethylene glycol copolymers, methylcellulose copolymers, ethylcellulose copolymers, polyvinylidene fluoride copolymers, polymethylmethacrylate copolymers, polyacrylonitrile copolymers, polyolefin copolymers. Saponified methylcellulose, saponified ethylcellulose, modified polyvinylidene fluoride, saponified polymethylmethacrylate, saponified polyacrylonitrile, polyolefin, modified polyolefin, modified polyimide, modified polyolefin copolymer, modified polyimide copolymer, polyamideimide, modified polyamideimide, modified poly Nonlimiting examples include tetrafluoroethylene, saponified polyvinyl alcohol, saponified polyvinyl butyrate, and preferably acid-modified polyolefins, particularly Mashiku the maleic acid-modified polyolefin.

  According to the present invention, it is preferable to use a mixture of the above-mentioned thermoplastic resin having a high melting point and a low melting point. Here, the high melting point resin has a melting point of 80 ° C. or higher, preferably 90 ° C. or higher, more preferably 95 ° C. or higher. The upper limit of the melting point of the high melting point resin is not particularly limited, and examples thereof include 140 ° C. The low melting point resin has a melting point of less than 80 ° C, preferably 75 ° C or less. The lower limit of the melting point of the low melting point resin is not particularly limited, and can be 60 ° C., for example. As a general tendency, high melting point resins have high crystallinity, and low melting point resins have low crystallinity. As a result of mixing the high melting point resin and the low melting point resin, the resin having a relatively high crystallinity forms an overall structure like a skeleton, and the crystal is formed so as to fill the gap between the “skeleton” made of the resin having a high crystallinity. It is assumed that there is a resin having low properties, and the overall heat resistance and mechanical strength are remarkably improved.

  In the present invention, at least one of the above-described resin coating film 16 covering the current collector layer 15 and the thermoplastic resin layer 17 for bonding the first and second substrates 11 and 12, preferably both. A mixture of the above-described high-melting thermoplastic resin and low-melting thermoplastic resin is used. Thereby, improvement in heat resistance and strength of the sealing structure of the fluid electrolyte 14 and prevention of erosion of the current collector layer 15 can be promoted significantly.

  The mixing ratio of the high melting point resin and the low melting point resin is not particularly limited. From the viewpoint of further enhancing the above effect, the high melting point resin is added to the total amount of 100 parts by weight of the high melting point resin and the low melting point resin. The resin is contained in an amount of 10 to 90 parts by weight, more preferably 20 to 40 parts by weight. The resin coating film 16 and / or the thermoplastic resin layer 17 described above may be manufactured by mixing three or more kinds of thermoplastic resins. In this case, each thermoplastic resin can be interpreted as a “high melting point resin” or a “low melting point resin” depending on the melting point.

  In manufacturing the DSSC according to the present invention, the first substrate 11, the second substrate 12, and the current collector layer 15 described above are prepared. At this time, for example, the catalyst layer 122 may be provided on the second substrate 12. As illustrated, the current collector layer 15 is formed on the transparent conductive film 111 described above. For the manufacture of the substrates 11 and 12, the prior art can be referred to as appropriate. For the current collector layer 15, for example, a conventional technique such as using a silver paste can be appropriately referred to.

  In order to bond the first and second substrates 11 and 12 together, a thermoplastic resin layer 17 is formed on at least one bonding surface thereof. A resin coating film 16 is also formed around the current collector layer 15 described above. As described above, a thermoplastic resin obtained by mixing a high melting point resin and a low melting point resin is used for at least one, preferably both of the thermoplastic resin 17 and the resin coating film 16. The formation method of the thermoplastic resin layer 17 and the formation method of the resin coating film 16 are not particularly limited, and the prior art can be referred to as appropriate. For example, a coating liquid (also referred to as “sealing agent solution” in the examples described later) in which a thermoplastic resin is dissolved or dispersed in a suitable solvent is manufactured, and this coating liquid is applied and then dried. Thus, the thermoplastic resin layer 17 and the resin coating film 16 can also be formed. Examples of specific drying conditions and the like are given in the examples described later.

  The first and second substrates 11 and 12 are bonded together, and the fluid electrolyte 14 is sealed between the first and second substrates 11 and 12 at appropriate times before and after the bonding or simultaneously with the bonding. The dye-supported oxide semiconductor layer 13 can also be formed at an appropriate stage. For the encapsulation of the fluid electrolyte 14 and the formation of the dye-carrying oxide semiconductor layer 13, the prior art can be referred to as appropriate. For this reason, a person skilled in the art can carry out the production method of the present invention based on the above description and the description of the claims, and obtain a DSSC in which heat resistance and mechanical strength can be remarkably improved. it can.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the embodiments described in these examples.

Conditions common to each example and comparative example are as follows.
The sealing agent solution includes an acid-modified polyolefin having a melting point of 75 ° C. and / or an acid-modified polyolefin having a melting point of 100 ° C. (total amount: 100 parts by weight), and 233 to 900 parts by weight of a hydrocarbon solvent and a polar solvent. It contains a solvent (ie, the acid-modified polyolefin concentration in the sealant solution is 10 to 30% by weight). This solvent is removed by drying at 120 ° C., which will be described later.

Example 1 Production of Optical Disc Type Dye-Sensitized Solar Cell A sealant solution comprising 70 parts by weight of acid-modified polyolefin having a melting point of 75 ° C. and 30 parts by weight of acid-modified polyolefin having a melting point of 100 ° C. did. Incidentally, 400 parts by weight of a hydrocarbon solvent and a polar solvent were added to the total weight of the acid-modified polyolefin to adjust the viscosity of the sealant solution. That is, the acid-modified polyolefin concentration in the sealant solution is 20% by weight.
The first substrate is a plastic / ITO substrate. A power generation layer adsorbing a pigment and a silver paste were arranged as a current collector layer on the ITO film of the substrate to form a negative electrode. The sealing agent solution was applied around the sealing portion (adhesive surface) on the ITO surface of the plastic / ITO substrate and the current collector layer, and dried at 120 ° C. for about 20 minutes.
The second substrate is a titanium electrode plate serving as a positive electrode. The above sealant solution was also applied to the sealing portion (adhesion surface) on the surface of the titanium electrode plate and dried at 120 ° C. for about 20 minutes.

  The sealing portions were made to face each other on the surface of the plastic / ITO substrate that was the negative electrode and the titanium electrode surface that was the positive electrode. A cell was manufactured by injecting an electrolytic solution using a dispenser on the inner side of the portion where the sealing agent solution was applied, and sealing the electrolytic solution between two electrodes by pressing the sealing portion while heating the sealing portion. .

The cell thus manufactured was subjected to a heating test at 80 ° C. for 12 hours, and the destruction and performance change of the sealing part before and after the heating were measured. The results are as follows.
Sealed part destruction before and after acceleration test: None Conversion efficiency decrease rate before and after acceleration test: 1.4%
Change in color of current collector layer (immersion of electrolyte in silver paste): None

(Example 2) Production of optical disk type dye-sensitized solar cell A sealing agent solution containing 50 parts by weight of acid-modified polyolefin having a melting point of 75 ° C and 50 parts by weight of acid-modified polyolefin having a melting point of 100 ° C was prepared. A cell was manufactured in the same manner as in Example 1 except that it was used, and an acceleration test was performed. The results are as follows.
Sealed part destruction before and after acceleration test: None Conversion efficiency decrease rate before and after acceleration test: 12.4%
Change in color tone of current collector layer (electrolyte immersion in silver paste): Existence In this example and the following examples, although electrolyte immersion in silver paste is observed, it has a significant effect on the results of accelerated tests Rather, it can be concluded that the resin sealing structure has excellent heat resistance and mechanical strength.

Example 3 Production of Optical Disc Type Dye-Sensitized Solar Cell A sealant solution comprising 30 parts by weight of acid-modified polyolefin having a melting point of 75 ° C. and 70 parts by weight of acid-modified polyolefin having a melting point of 100 ° C. A cell was manufactured in the same manner as in Example 1 except that it was used, and an acceleration test was performed. The results are as follows.
Sealing part destruction before and after the acceleration test: None Conversion efficiency decrease rate before and after the acceleration test: 12.8%
Change in color of current collector layer (immersion of electrolyte in silver paste): Available

Example 4 Production of Optical Disc Type Dye-Sensitized Solar Cell A sealant solution comprising 10 parts by weight of acid-modified polyolefin having a melting point of 75 ° C. and 90 parts by weight of acid-modified polyolefin having a melting point of 100 ° C. A cell was manufactured in the same manner as in Example 1 except that it was used, and an acceleration test was performed. The results are as follows.
Sealed part failure before and after acceleration test: None Conversion efficiency decrease rate before and after acceleration test: 24.0%
Change in color of collector electrode (immersion of electrolyte in silver paste): Available

Comparative Example 1 Preparation of Optical Disc Type Dye-Sensitized Solar Cell As in Example 1, except that a sealant solution containing 100 parts by weight of acid-modified polyolefin having a melting point of 100 ° C. was used. The cell was manufactured and subjected to an accelerated test. The results are as follows.
Sealed part destruction before and after acceleration test: None Conversion efficiency decrease rate before and after acceleration test: 26.3%
Change in color of current collector layer (immersion of electrolyte in silver paste): Available

Comparative Example 2 Production of Optical Disc Type Dye-Sensitized Solar Cell As in Example 1, except that a sealant solution containing 100 parts by weight of acid-modified polyolefin having a melting point of 75 ° C. was used. The cell was manufactured and subjected to an accelerated test. The results are as follows.
Sealed part destruction before and after acceleration test: Yes Conversion efficiency decrease rate before and after acceleration test: 70% or more Color change of current collector layer (electrolyte immersion in silver paste): Yes

DESCRIPTION OF SYMBOLS 11: 1st board | substrate 12: 2nd board | substrate 13: Dye carrying | support oxide semiconductor layer 14: Fluid electrolyte 15: Current collector layer 16: Resin coating film 17: Thermoplastic resin layer

Claims (4)

Providing a first substrate having an adhesive surface and having a transparent conductive film, a second substrate having an adhesive surface, and a current collector layer made of metal formed on the transparent conductive film;
Forming a resin coating around the current collector layer;
Forming a thermoplastic resin layer on at least one adhesive surface of the first and second substrates;
A step of bonding the first and second substrates so as to secure a region in which the fluid electrolyte is sealed by facing each of the bonding surfaces; and at the same time as the bonding or before or after the bonding, And encapsulating a flowable electrolyte between the second substrate;
A manufacturing method comprising:
At least one of the resin coating film and the thermoplastic resin layer contains a thermoplastic resin having a melting point of less than 80 ° C. and a thermoplastic resin having a melting point of 80 ° C. or more.
A method for producing a dye-sensitized solar cell.   The method according to claim 1, wherein both the resin coating film and the thermoplastic resin layer contain a thermoplastic resin having a melting point of less than 80 ° C and a thermoplastic resin having a melting point of 80 ° C or more.   The method according to claim 1 or 2, wherein both the thermoplastic resin having a melting point of less than 80 ° C and the thermoplastic resin having a melting point of 80 ° C or more are acid-modified polyolefins.   The dye-sensitized solar cell obtained by the manufacturing method of any one of Claims 1-3.

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