TW201304244A - Polymer electrolytes for dye-sensitized solar cells and method for manufacturing modules of dye-sensitized solar cells using the same - Google Patents

Abstract

This disclosure provides polymer electrolytes for dye-sensitized solar cells and methods for manufacturing modules of dye-sensitized solar cells using the same, and more specifically to polymer electrolytes for dye-sensitized solar cells that can not only prevent electrolyte from leaking which is one of the worst drawbacks in conventional dye-sensitized solar cells using liquid electrolytes, but also exhibit a higher solar conversion efficiency compared with conventional polymer electrolytes and be applicable to a process for manufacturing dye-sensitized solar cells with a large surface area or flexible dye-sensitized solar cells, and methods for manufacturing modules of dye-sensitized solar cells using the same. The polymer electrolyte for a dye-sensitized solar cell in accordance with the present disclosure comprises a heat-curable epoxy resin, an imidazole-based curing accelerator, and metal salts, and a method for manufacturing a module of dye-sensitized solar cells using the polymer electrolyte for a dye-sensitized solar cell, is characterized by using the above polymer electrolyte for a dye-sensitized solar cell, wherein the polymer electrolyte for a dye-sensitized solar cell is used as an adhesive product between a working electrode and a counter electrode and a final form of bonding is maintained in a solid phase.

Description

Polymer electrolyte for dye-sensitized solar cell and method for manufacturing module of dye-sensitized solar cell using said polymer electrolyte

The present invention generally relates to a polymer electrolyte for a dye-sensitized solar cell and a method of manufacturing a module for dye-sensitized solar cells using the polymer electrolyte, and more specifically for dye-sensitized solar cells as follows Polymer electrolyte: it not only prevents electrolyte leakage, but also is one of the worst drawbacks of conventional dye-sensitized solar cells using liquid electrolytes, and exhibits higher solar energy conversion efficiency than conventional polymer electrolytes, and is applicable. A process for producing a large surface area dye-sensitized solar cell or a flexible dye-sensitized solar cell; and a method of manufacturing a module of a dye-sensitized solar cell using the polymer electrolyte.

In recent years, due to the world's investment in alternative energy industries and green growth policies, the photovoltaic cell or solar cell market is growing rapidly, and therefore, solar cell module production is expected to grow at a rate of 50% or more per year. . In detail, according to NanoMarkets (Glass Allen, Va.), the production of solar modules is expected to increase from 6 GW in 2008 to 34.7 in 2015. MW.

However, since the structural problem of the solar cell using the crystalline germanium (because the manufacturing process of the crystalline germanium is extremely complicated and the productivity is extremely low by batch production, the price of the solar cell module is high), the amorphous germanium has recently been developed. A thin film solar cell or other product formed by depositing germanium by using a highly flexible and lightweight stainless steel or polyimide. However, although such products have the advantage of being relatively light in weight and reducing their production cost, the efficiency of such solar cells is about 6%, which is a crystallization with an efficiency of about 7 to 20% and a short service life.矽 Solar cells are much lower.

Due to the above problems, although attempts have been made to develop solar cells using organic materials instead of using solar cells, solar cells using the organic materials have disadvantages of low energy conversion efficiency and in particular have durability problems. Federal Institute of Technology, Lausanne, Switzerland ( Cole Polytechnique F d Michael Gr of rale de Lausanne in Switzerland) Professor Tzel proposed a new type of solar cell, a dye-sensitized solar cell composed of photosensitive dye particles and titanium dioxide nanoparticles, and reported an extremely high energy conversion efficiency of about 10%, which is in the conventional inorganic solar cell. Solar cells based on the amorphous iridium series are equivalent. The dye-sensitized solar cell described above is known to have a very high commercialization possibility because its production cost is only about 20% of that of a solar cell, and therefore, the world has conducted extensive investigations for practical applications.

Most importantly, the low economic viability has become a problem due to the high production cost of the solar cell and the efficiency limitations of the battery itself during the development of the above solar cell. In addition, there is an urgent need to develop readily available solar cell modules as an alternative energy source in daily life. Although the industry has so far focused on the development of solar cells based on germanium, it is expected that the future development of solar cells will open up new properties suitable for dye-sensitized solar cells, organic solar cells and thin film solar cells. Application, and at the same time gradually need new technology. In particular, since the solar cell generates electricity only under a very large amount of light, since the dye-sensitized solar cell generates electricity even in a small amount of direct sunlight, it is used as a building that generates electricity using building walls and windows. Integrating photovoltaic systems, dye-sensitized solar cells produce electricity more efficiently than helium solar cells. Therefore, although solar cells can be further developed into large-scale power plants in the future, it is expected that most of the photovoltaic generations using buildings in daily life are covered by dye-sensitized solar cells. In addition, since it is desired that the applicability of the solar cell is extended to various electronic instruments or small portable parts and automobiles using indoor lighting, and even applied to clothes due to environmental protection, transparency, and coloring and efficiency at low light amount. Therefore, the industry is conducting a large number of investigations on commercial applicability.

The dye-sensitized solar cell was first developed by Michael Gr Professor Tzel was invented based on the principle of plant photosynthesis and consisted of a working electrode, an inorganic oxide layer (such as titanium dioxide) to which dye molecules were attached, a liquid electrolyte, and a counter electrode. Photoelectric conversion occurs via photoelectrochemical reactions between the electrodes, which are briefly explained below.

First, the working electrode is composed of a nano-sized oxide semiconductor to which a molecular dye that absorbs sunlight to emit electrons is adhered. When external light reaches the molecular dye, the electrons in the dye are excited to a high level of energy, which is then received by the oxide semiconductor and transferred to the outside. Electrons with a high degree of energy consume their energy while flowing through an external circuit and then to the opposite electrode. The dye that emits electrons in the working electrode receives electrons back through the electrolyte, and the redox process occurs continuously during the supply of energy via ion transfer in the electrolyte.

Therefore, the electrolyte plays an extremely important role in transferring electrons via ionization, and in particular, the contact area between the electrode and the electrolyte determines the amount of electric power generated. In other words, because the wider the contact area, the faster and more likely the reaction can occur and the more the amount of dye that can be adhered, the nanoparticles are used as the material for the respective electrodes. If nanoparticles are used, the surface area of the material is significantly increased for the same volume, and therefore, a greater amount of dye can be adhered to the surface of the material, thereby increasing the rate of electrochemical reaction between the electrode and the electrolyte. In general, the titanium dioxide semiconductor oxide electrode used to form the working electrode is coated with nanoparticle having a thickness of 10 to 20 μm and having a size of about 20 to 50 nm, and the dye is adhered to the surface. Further, the opposite electrode is coated on the substrate with a thin layer of platinum particles having a size of less than 10 nm.

On the one hand, a dye-sensitized solar cell using a conventional liquid electrolyte has inherent problems in stability and durability, such as deterioration of properties caused by electrolyte leakage and solvent evaporation, thereby hindering commercialization thereof. In particular, the dye-sensitized solar cell cannot be fabricated into a large-area battery due to the process of injecting the electrolyte, which makes it difficult to achieve low production costs, which is one of the main benefits of the dye-sensitized solar cell. In view of the facts, there is an urgent need to develop a solid or semi-solid electrolyte in place of a liquid electrolyte.

For the above reasons, the industry has tried to replace liquid electrolytes with solid or semi-solid electrolytes. The research and development of an organic polymer or an inorganic hole transfer material (HTM) for the solid or semi-solid electrolyte has been carried out, and in particular, it is mainly aimed at an organic polymer electrolyte which is advantageous for commercialization. This is because the organic polymer electrolyte makes it possible to change its shape during the manufacture of the solid dye-sensitized solar cell to provide flexibility, and to manufacture a film using a technique such as spin coating, which is also one of the advantages. In addition, it maintains stable performance under thermal stress or light infiltration compared to liquid electrolytes, and can contribute to improving long-term stability and providing low production cost advantages. Examples of commonly used polymers include PEO, poly(propylene oxide), PPO, poly(ethylene imine), PEI, poly(ethyl sulfide) (poly) Ethylene sulphide); PES), poly(vinyl acetate), PVAc, poly(ethylene succinate), PESc, etc. Investigations have been made because it is known that ion movement in the polymer electrolyte occurs in the amorphous region by means of segmental movement of the polymer chain. A composite of poly(ethylene oxide) (PEO) and an alkali metal salt is the most widely known polymer electrolyte.

The polymer electrolyte was first proposed by the Wright Group in 1975 by the preparation of a complex of poly(ethylene oxide) with an alkali metal salt, and was subsequently applied to a lithium battery pack of polymer electrolytes and electrification by Armand et al. in 1978. learn. Most of the conventional polymer electrolytes reported so far are based on PEO, and since the conductivity of the metal salt is mixed, since the fuel cell, PEO has been the most widely reported as a representative material of the polymer electrolyte. Based on the reports, PEO has become one of the most attractive research topics in polymer electrolytes for dye-sensitized solar cells. This is because PEO is suitable for solid dye-sensitized solar cells because it exhibits various properties (depending on its molecular weight), has excellent chemical stability, and exhibits higher mechanical strength than liquid electrolytes. In particular, PEO is known to have a regular arrangement of a large number of oxygen atoms and an ion transfer mechanism for transferring metal cations via a helical structure formed by a polymer chain. Further, the polymer electrolyte is preferably composed of a metal salt having a low lattice energy such as an alkali metal such as LiI, KI, NaI and the like; and a polymer having a polar group capable of dissociating the metal salt . Therefore, the polymer needs to contain a lone pair of electrons capable of donating electrons, such as oxygen (O) or nitrogen (N), and the polar group and the metal cation reach a coordination bond to form a polymer-metal salt. Complex.

However, since PEO exhibits substantially high crystallinity due to high molecular weight, it is necessary to limit high molecular weight in consideration of durability. The crystallinity (about 80%) of PEO has the disadvantage of having low ionic conductivity (10-8 to 10-5 Siemens/cm (Scm-1)) and a diffusion coefficient at room temperature. In addition, depending on the chain size of the polymer, how much of the polymer electrolyte can penetrate into the pores of the nanosized titanium dioxide oxide layer is an important factor and it is difficult for PEO having a high molecular weight to penetrate into the oxide layer, which not only reduces energy. Conversion efficiency, and in fact shows the limitations of manufacturing solar cells. Therefore, although various methods for reducing the crystallinity of the PEO-based electrolyte, increasing the ionic conductivity and the diffusion coefficient, and improving the energy conversion efficiency by improving the interface contact have been investigated, the results have so far been useless.

The main reason for the above problem is that the ionic conductivity is inherently low in the solid phase. In order to overcome the disadvantages, investigations have been actively conducted relating to semi-solid or gel-type polymer electrolytes utilizing intermediate features between liquid and solid. The Korean Patent Application Publication No. 2003-65957 describes a semi-solid polymer electrolyte by way of example, and claims that the semi-solid polymer electrolyte exhibits high ion conductivity similar to that of a liquid electrolyte at room temperature. However, semi-solid polymer electrolytes have lower durability than solid polymer electrolytes because they exhibit weak mechanical properties, such as glass transition temperature (Tg), and the process of manufacturing solar cells is due to semi-solid characteristics. It is difficult, and because the solvent is mixed with it, it is difficult to completely prevent electrolyte leakage.

As described above, most of the polymer electrolyte is based on poly(ethylene oxide) (PEO), and therefore, it is important to increase the amorphous region by reducing its crystallinity. For this purpose, improving ionic conductivity and reducing crystallinity by adding nanoparticles, crosslinking, blending, forming copolymers or the like are the main research topics of polymer electrolytes, and it is possible to adjust the polymer by Molecular weight or end groups to achieve another performance improvement.

For example, in 2001, Professor De Paoli of Brazil reported a first dye-sensitized solar cell using a polymer electrolyte without solvent and prepared from poly(epichlorohydrin-co-ethylene oxide)/ A polymer electrolyte composed of NaI/I ₂ exhibits an efficiency of 1.6% at 100 mW/cm 2 . Then, in 2002, a group of researchers called Flaras from Greece (Greece) mixed high-crystallinity PEO electrolytes with titanium oxide nanoparticles and presented PEO results with reduced crystallinity, and Professor Flavia Nogueira used and de Professor Paoli's group of the same poly(epichlorohydrin-co-ethylene oxide) prepared titanium oxide in the form of a nanotube to reduce its crystallinity and reported a solar conversion efficiency of up to 3.5%.

However, the results of the survey of the conventional survey studies described above have little meaning and there is no development of commercially available products. Therefore, in order to commercialize the efficiency and durability of dye-sensitized solar cells as early as possible, it is urgent to develop novel polymer electrolytes.

To this end, the inventors have designed a novel polymer electrolyte and its assembly process that overcomes the limitations of conventional polymer electrolytes based on PEO. In view of the industry's prior art, despite the development of new transparent electrodes, new semiconductor materials and technologies for manufacturing new semiconductor materials, techniques for absorbing dyes of various wavelengths, development of new materials for counter electrodes, and fabrication for opposing electrodes The technology of new materials and the like have reached commercialization, but the use of liquid electrolytes still has the same limitations, and the polymer electrolyte according to the present invention will have a certain great effect in the art to which the present invention pertains.

[Previous Technical Literature] [Patent Literature]

(Patent Document 1) Korean Patent Application Publication No. 2003-65957

[Non-patent literature]

Kinetics study of imidazole-cured epoxy-phenol resins, Yi-Cheng Chen et al., Polymer Chemistry, Vol. 37, No. 16, pp. 3233-3242.

The present invention provides a polymer electrolyte for a dye-sensitized solar cell which not only prevents electrolyte leakage, but is one of the worst drawbacks of a conventional dye-sensitized solar cell using a liquid electrolyte, and is compatible with a conventional polymer electrolyte. Method for producing higher solar energy conversion efficiency and suitable for manufacturing a large surface area dye-sensitized solar cell or a flexible dye-sensitized solar cell; and a method for manufacturing a module of a dye-sensitized solar cell using the polymer electrolyte .

These and other features and advantages of the present invention will become apparent from the following description of the preferred embodiments.

The above object is achieved by a polymer electrolyte for a dye-sensitized solar cell comprising a heat curable epoxy resin, an imidazole-based curing accelerator, and a metal salt. Here, the heat curable epoxy resin has 2 to 8 functional groups, and a molecular weight of 500 to 8,000.

Preferably, the content of the imidazole-based curing accelerator is from 0.1 part by weight to 20 parts by weight per 100 parts by weight of the heat curable epoxy resin.

The content of the metal salt is preferably from 1 part by weight to 200 parts by weight per 100 parts by weight of the heat curable epoxy resin.

Preferably, the polymer electrolyte used in the dye-sensitized solar cell has a viscosity of from 10 centipoise to 8,000 centipoise.

In addition, the above object is further achieved by a method of manufacturing a module of a dye-sensitized solar cell using a polymer electrolyte for a dye-sensitized solar cell, wherein the above-mentioned polymer electrolyte for a dye-sensitized solar cell is used, and the above The polymer electrolyte of the dye-sensitized solar cell is used as an adhesive product between the working electrode and the opposite electrode and the final form of bonding is maintained as a solid phase.

Preferably, the bonding between the electrodes is hot melt bonding.

More preferably, the bonding between the electrodes is continuous roll coating or continuous roll hot melt using a flexible substrate.

[The role of the present invention]

A polymer electrolyte for a dye-sensitized solar cell and a method for manufacturing a module for a dye-sensitized solar cell using the polymer electrolyte according to the present invention have the following effects: not only prevention of electrolyte leakage, but also a conventional dye sensitivity using a liquid electrolyte One of the worst drawbacks of solar cells, and exhibits higher solar conversion efficiency than conventional polymer electrolytes, and is suitable for the manufacture of large surface area dye-sensitized solar cells or flexible dye-sensitized solar cells.

Preferred embodiments of the present invention will be described in detail below. It is to be understood that the embodiments of the present invention are intended to be understood by those skilled in the art

The present invention relates to a polymer electrolyte for constituting a dye-sensitized solar cell, and the polymer electrolyte is composed of a heat curable epoxy resin and contains an imidazole-based curing accelerator and a metal salt. Thus, it is possible to provide an excellent polymer electrolyte for a dye-sensitized solar cell which not only prevents electrolyte leakage, but is one of the worst drawbacks of the conventional dye-sensitized solar cell using a liquid electrolyte, and is suitable for manufacturing. Process for large surface area dye-sensitized solar cells or flexible dye-sensitized solar cells.

The present inventors have devised the following characteristics of polymeric compositions in order to design novel polymer electrolytes that substantially solve the electrolyte leakage problems present in conventional liquid electrolytes and are suitable for use in the fabrication of large surface area solar cells or flexible solar cells. Guidelines:

1) a polymeric composition having a branched structure that is difficult to crystallize,

2) a polymeric composition having excellent interfacial adhesion and capable of easily penetrating into the pores of the titanium oxide oxide layer,

3) a polymeric composition having excellent adhesion strength between the working electrode and the opposite electrode and having excellent durability,

4) a polymeric composition capable of undergoing metal salt dissociation and ion transport, and

5) An assembly process capable of performing solution coating and film bonding of a hot melt type at the same time.

To achieve the above criteria, the inventors have devised the use of a heat curable epoxy resin as a novel polymer electrolyte. According to the general knowledge of the use of epoxy resins for insulating materials, epoxy resins have limitations in their use as electrolytes; however, the inventors have achieved the following reversal from the study of the characteristics of solid electrolytes required for dye-sensitized solar cells. The design basis of the contrarian approach:

1) The epoxy resin forms a three-dimensional (3D) network cross-linking structure capable of transferring metal cations,

2) Epoxy resin contains a large number of polar groups capable of dissociating metal salts,

3) The epoxy resin has a low molecular weight at the beginning of curing, so that it can easily penetrate into the nano-sized titanium oxide oxide layer during the manufacture of the solar cell,

4) Epoxy resin has good adhesion strength and durability after curing, and

5) The epoxy resin can be made into a solvent-free liquid, semi-solid or pure solid type, so that solution coating and film type hot melt bonding may be performed during the manufacture of the solar cell.

The polymer electrolyte for a dye-sensitized solar cell according to the present invention is composed of a heat curable epoxy resin as a matrix polymer, and contains an imidazole-based curing accelerator and a metal salt as an ion or charge transfer carrier. Since the heat curable epoxy resin has a large number of regular oxygen atoms in its main chain, it can easily dissociate the metal salt for use as an electrolyte, thereby making it possible to produce a liquid type to solid type electrolyte having a low molecular weight. Therefore, in the case of a process for manufacturing a dye-sensitized solar cell, it is possible to carry out a process of solution coating or hot-melt type bonding of a module and it is possible to manufacture an excellent module adhesion by solidification by heat curing. And durable dye-sensitized solar cells.

Further, the polymer electrolyte for a dye-sensitized solar cell according to the present invention is obtained by mixing a liquid phase or solid phase heat curable epoxy resin with an imidazole-based curing accelerator, and then using a common mixing technique according to the required amount. The method is prepared by adding a metal salt as an ion transport carrier. In particular, in the case of using a solid phase heat curable epoxy resin, a polar solvent such as ethyl methyl ketone is also used in order to prepare a liquid phase heat curable epoxy resin.

The method of mixing the polymer electrolyte for a dye-sensitized solar cell according to the present invention is not particularly limited, and examples of the method may include using a Banbury mixer, a single screw extruder, and a twin screw A melt mixing method of an extruder and the like, and a method of mixing a solution by stirring (solution blending). Among them, a method of mixing a solution by stirring is preferably used. Further, it is necessary to appropriately use the dispersion mixing and the distribution mixing at the same time to distribute the metal salt in the epoxy resin in an equilibrium manner during the mixed solution. For this purpose, it is preferred to dissolve the metal salt in a small amount of epoxy resin prior to preparation of the masterbatch, followed by injection while mixing.

The epoxy resin used in the present invention may be initially in a liquid or solid form, and it may be prepared by mixing two or more kinds as needed. For example, if no solvent is used during the formation of the electrolyte coating layer, the liquid epoxy resin may be used to apply the solution to the opposite electrode on which the titanium oxide oxide layer is formed. In addition, if the epoxy resin is subjected to a drying process by using a solvent, the solid electrolyte coating layer can be dried by first dissolving the solid epoxy resin in a solvent, followed by coating on the opposite electrode. Increased to exceed the boiling point of the solvent to form.

The polymer electrolyte for a dye-sensitized solar cell according to the present invention has a viscosity capable of solution coating, preferably from 10 centipoise to 8,000 centipoise, more preferably from 50 centipoise to 3,000 centipoise. Even more preferably from 100 centipoise to 500 centipoise. This is because if the viscosity is less than 10 centipoise, it is difficult to ensure a distance from the opposite electrode when the electrolyte layer is formed on the working electrode on which the oxide semiconductor layer is formed, and if it is higher than 8000 centipoise, it is difficult for the electrolyte to penetrate into the oxide semiconductor. The nanometers of the layer are dimensioned in the pores. Solid dye-sensitized solar cells exhibit lower energy conversion efficiencies than liquid dye-sensitized solar cells, and this is primarily due to the low conductivity of the solid electrolyte and incomplete contact between the electrolyte and the electrodes. Thus, a high electron recombination rate is generated between the photoelectrode and the solid electrolyte, thereby affecting the overall efficiency. In the case where the polymer electrolyte does not smoothly penetrate into the nanosized pores of the semiconductor oxide layer, the transfer efficiency of electrons emitted from the dye is lowered, which in turn directly reduces the energy conversion efficiency and exhibits practical limitations for manufacturing solar cells. Therefore, if a low molecular weight epoxy resin is used as the matrix polymer forming the electrolyte (as in the present invention), the electrolyte is infiltrated into the semiconductor oxide layer and the generation of current in the working electrode is increased, thereby solving the existence of the electrode in the solid electrolyte. Poor contact.

In addition, since the epoxy resin has an intrinsic adhesive property, it can impart durability not only by providing adhesive strength during bonding of the working electrode and the opposite electrode during manufacture of the solar cell module, but also avoiding the use of a conventional liquid electrolyte. In this case, it is a necessary encapsulation process, which significantly increases the productivity when manufacturing large surface area solar cells.

Further, the polymer electrolyte for a dye-sensitized solar cell according to the present invention can be prepared in various ways. For example, in the case of manufacturing a large surface area solar cell module, it is possible to use a method in which polymerization is carried out using a known roll knife coater, gravure coater, die coater or reverse coater. The electrolyte mixture is coated on the substrate on which the semiconductor oxide layer is formed, and then dried to form a polymer electrolyte layer, and the opposite electrode is deposited on the polymer electrolyte layer via roll lamination; or the following method, wherein the use is known The technique applies a polymer electrolyte layer separately to the opposite electrode, followed by drying, and lamination on the working electrode, and the polymer electrolyte is infiltrated into the semiconductor oxide layer by applying heat. Alternatively, in the case of manufacturing a small surface area solar cell, it is also possible to simply prepare a polymer electrolyte solution, which is then applied to the respective electrodes via spin coating.

In the case where the electrolyte layer is formed on the large-area glass substrate by the above-described process for manufacturing a solar cell module, it is necessary to carry out the process of injecting the liquid electrolyte and sealing it for a long time in view of the conventional method, but if the polymer of the present invention is used, Electrolyte, it is possible to use not only solution coating but also hot melt bonding, and if a flexible substrate such as a polymer film is used as an electrode material, a continuous process may be performed in order to mass-produce a large surface area dye-sensitized solar cell. .

Further, the epoxy resin used in the present invention is not particularly limited as long as it exhibits an adhesive reaction after curing. An epoxy resin having 2 to 8 functional groups and preferably having a molecular weight of 500 to 8,000 and more preferably 500 to 3,000 may be used. For example, it is possible to use a bifunctional epoxy resin such as bisphenol A epoxy resin or bisphenol F epoxy resin, or a novolac epoxy resin such as a phenol novolac epoxy resin or a cresol novolac epoxy resin. In addition, it is also possible to use a polyfunctional epoxy resin or a heterocyclic epoxy resin.

Further, the polymer electrolyte for a dye-sensitized solar cell according to the present invention includes an imidazole-based curing accelerator to initiate a curing reaction of the heat curable epoxy resin. The imidazole-based curing accelerator initiates a curing reaction of the heat curable epoxy resin to develop an amorphous solidified structure after reacting with the epoxy resin and simultaneously form a cationic connection point, thereby promoting metal salt dissociation and ion transfer to enhance the dye Sensitize the efficiency of solar cells.

More specifically, the polymer electrolyte of the present invention includes a curing accelerator based on imidazole to form a cured structure of a branched structure. The polymer electrolyte forms a branched structure by polyetherifying a nitrogen atom attached to a side chain of an imidazole-based curing accelerator and an epoxy resin (Kinetics study of imidazole-cured epoxy-phenol resins, Yi-Cheng Chen et al.: PolymerChemistry , Vol. 37, No. 16, pp. 3233-3242). In this way, it is possible to obtain an amorphous solidified structure of the epoxy resin via ion polymerization, and the thus obtained epoxide solidified structure contains a branch free volume, thereby being capable of transferring metal cations and anions.

The curing accelerator used in the polymer electrolyte for a dye-sensitized solar cell according to the present invention may be limited to imidazole. Examples of the imidazole may include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-benzyl-4-methylimidazole, 1-(2-cyanoethyl)-2-ethyl 4-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-(2-cyanoethyl)2-phenyl-4,5-di-(cyanoethoxymethyl Imidazole or the like, and it is possible to use one or two or more of the above imidazoles at the same time. Some commercially available imidazoles include, for example, products manufactured by Shikocu Kasei Kogyo Co., Ltd. under the names 2,4 EMIZ, 2B4 MIZ, 2-EI, 2-PI, 2-PDHMI, 2E4MZ, 2PZ-CN, 2PZ-CNS. The content of the imidazole-based curing accelerator is preferably from 0.1 part by weight to 20 parts by weight per 100 parts by weight of the epoxy resin, and because if the content is less than 0.1 part by weight, it is difficult to form a branched structure because the epoxy resin cannot be smoothly Curing, and if it exceeds 20 parts by weight, the epoxy resin cures too quickly, causing a serious change with time in the preparation of the electrolyte.

Although it is possible to use an amine curing agent having a primary or secondary amine group as a curing accelerator for use in the polymer electrolyte for a dye-sensitized solar cell of the present invention, in this case, a linear chain is formed as a final curing. Structure, which ultimately increases the disadvantage of its crystallinity. Therefore, it is necessary to use an imidazole capable of performing ion polymerization in a crosslinked form.

Further, the polymer electrolyte is usually composed of a polymer having a polar group as a basic framework, and is composed of a metal salt having a low lattice energy to provide an alkaline series of oxidation/reduction pairs. The cation of the metal salt of the polymer and the polar group such as oxygen or nitrogen reach a coordination bond via a Lewis acid-base interaction in the electrolyte to produce an I- or I3-oxidation/reduction pair. The resulting oxidation/reduction pair forms or consumes electrons via an oxidation/reduction reaction. Furthermore, electrons are transported in the polymer electrolyte by ion movement, and it is known that ion movement in the polymer electrolyte occurs in the amorphous region by means of segmental movement of the polymer chain. Therefore, the ionic conductivity is directly dependent on the mobility of the polymer chain, and the concentration of charge carriers also has a large effect. The Mitate team proposes that to improve the energy conversion efficiency of quasi-solid-state DSSCs, polymer networks need to contain large amounts of liquid electrolytes by forming structures through chemical bonds. The reactive molecules are chemically bonded to one another via crosslinking in a polymer network to form a 3-D network. In the present invention, an epoxy resin is used to form a polymer network in a solid phase branched form, and an imidazole-based curing accelerator is used as a crosslinking point to increase anion mobility by an I-, I3-oxidation/reduction pair.

The redox derivative used in the solid polymer electrolyte of the present invention may include a substance capable of providing an oxidation/reduction pair, such as a metal halide such as LiI, NaI, KI, BrI, sodium bromide, and potassium bromide; and nitrogen Iodides of heterocyclic compounds, such as imidazolium salts, pyridinium salts, quaternary ammonium salts, pyrrolidinium salts, pyrazolidine salts, isothiazolidinium salts, and isoxazolidinium salts. The organic solvent may include acetonitrile, 3-methoxypropionitrile, ethyl carbonate, propyl carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, tetrahydrofuran or γ-butyrolactone.

The content of the metal salt in the polymer electrolyte for a dye-sensitized solar cell according to the present invention is preferably from 1 part by weight to 200 parts by weight per 100 parts by weight of the heat curable epoxy resin, and this is because if the content of the metal salt is When it is less than 1 part by weight, it is difficult to achieve ionic conductivity, and if it exceeds 200 parts by weight, the electrolyte cannot be prepared due to excessive condensation of the metal salt.

Further, a method of manufacturing a module of a dye-sensitized solar cell using a polymer electrolyte for a dye-sensitized solar cell is a method of manufacturing a solar cell using the above-described polymer electrolyte for a dye-sensitized solar cell, wherein the method is The polymer electrolyte of the dye-sensitized solar cell is used as an adhesive product between the working electrode and the opposite electrode and the final form of bonding is maintained as a solid phase.

The bonding between the electrodes is hot melt bonding, or the bonding between the electrodes is continuous roll coating or continuous roll hot melt using a flexible substrate.

The invention will be described in detail below by means of preferred embodiments and comparative examples. However, the invention is not limited to the embodiment.

[Example 1]

(1) Manufacturing working electrode

After preparing the FTO glass substrate, the coating composition containing titanium oxide (TiO ₂ ) was applied onto the transparent conductive oxide layer of the substrate by a doctor blade method, followed by heat treatment at 520 ° C for 40 minutes. Nano-sized contacts and fills between the metal oxides result in a nano-oxide layer having a thickness of about 7 microns. The thickness was adjusted using a 3M Scotch Magic Tape as a spacer. Subsequently, the same coating composition was applied on the nano oxide layer by the same method, followed by heat treatment at 520 ° C for 40 minutes to produce a nano oxide layer having a thickness of about 15 μm. Next, a dye solution was prepared using Solonix N-719 dye and ethanol, in which the substrate on which the nano oxide layer was formed was immersed for 48 hours, and then the substrate was dried to allow the nanosized metal oxide to absorb the dye, thereby producing a negative electrode.

(2) manufacturing opposite electrodes

After preparing the FTO glass substrate, a ₂ -propanol solution in which H ₂ PtCl _{6 was} dissolved was applied onto the transparent conductive oxide layer of the substrate by spin coating, followed by heat treatment at 480 ° C for 30 minutes to form a platinum layer. Thereby a positive electrode is produced.

(3) Preparation of polymer electrolyte

Sample-1

100 parts by weight of cresol novolac epoxy resin (YDCN 8P of Toto Kasei Co.) and 2 parts by weight of 1-cyanoethyl-2-phenylimidazole (Curezol 2PZ-CN of Shikocu Kasei Kogyo Co., Ltd.) were added. Thereafter, it was stirred for 3 hours in a methyl ethyl ketone solvent, and 5 parts by weight of LiI (Sigma-Aldrich) was mixed and stirred for 12 hours to obtain a mixed solution of a polymer electrolyte.

Sample-2

The same method as Sample-1 was used except that 10 parts by weight of LiI was used.

Sample-3

The same method as Sample-1 was used except that 30 parts by weight of LiI was used.

Sample-4

The same method as Sample-1 was used except that 50 parts by weight of LiI was used.

(4) Manufacturing a dye-sensitized solar cell module

The polymer electrolyte solution prepared as described above was applied onto the working electrode fabricated as described above by mayer bar coating, followed by drying at 80 ° C for 5 minutes, and removing the solvent to obtain A polymer electrolyte layer having a thickness of about 50 microns. Subsequently, the opposite electrode was deposited and compressed by hot pressing at 130 ° C and 0.01 MPa to produce a dye-sensitized solar cell without a separate encapsulation process.

[Embodiment 2]

The same procedure as in Example 1 was carried out except that 100 parts by weight of a bisphenol A type liquid epoxy resin (YD128 of Toto Kasei Co.) was used instead of the cresol novolac epoxy resin to prepare a polymer electrolyte.

[Comparative Example 1]

The same procedure as in Example 1 was carried out except that 100 parts by weight of polyethylene oxide (PEO of Sigma-Aldrich) was used instead of the cresol novolac epoxy resin to prepare a polymer electrolyte; the curing accelerator was removed; and acetonitrile (Sigma-Aldrich) was used. As a solvent, the solution was dispensed in a solid content in a dilution ratio of 5 parts by weight to 30 parts by weight so that 5 parts by weight was first applied, followed by waiting for 2 hours, followed by application of 30 parts by weight to produce an electrolyte layer.

[Test Example 1]

To evaluate the ionic conductivity of the polymer electrolyte prepared in the above Examples and Comparative Examples, an ion conductivity value was measured using an impedance analyzer and using Mathematical Formula 1 below.

[Mathematical Formula 1]

R=r×(l/A),

"R" is the impedance, "r" is the ionic conductivity, "l" is the distance between the electrodes, and "A" is the measured cross-sectional area of the sample.

[Test Case 2]

In order to evaluate the solar energy conversion efficiency of the dye-sensitized solar cell produced in the above examples and comparative examples, the photovoltage and photocurrent were measured in the following manner to observe the photoelectricity. The solar energy conversion efficiency (η) was calculated by the following Mathematical Formula 2 using the current density (I _sc ), the open circuit voltage (V _oc ), and the fill factor (ff) thus obtained. In this case, a xenon lamp (Oriel) is used as a light source, and a standard solar cell is used to compensate the sunlight condition of the xenon lamp (AM 1.5).

[Mathematical Formula 2]

η(%)=(Voc×Isc×ff)/(P)

In the above mathematical formula 2, "p" represents 100 mW/cm 2 (1 standard solar intensity (1 sun)).

The values measured in the above Test Examples 1 and 2 were measured at room temperature and are shown in Table 1 below.

("Emb." indicates an embodiment, "Spc." indicates a sample, and "Comp. Ex." indicates a comparative example.)

As shown in Table 1 above, it can be seen that the polymer electrolytes according to Example 1 and Example 2 of the present invention exhibit high ionic conductivity at room temperature, and are comprised of polymer electrolytes (including polyethylene oxide, which are A dye-sensitized solar cell comprising a coating made of the polymer electrolyte of Example 1 and Example 2 of the present invention, compared to the dye-sensitized solar cell of Comparative Example 1 Shows increased current density and voltage, and improved solar conversion efficiency.

Claims (8)

A polymer electrolyte for a dye-sensitized solar cell, comprising: a heat curable epoxy resin, an imidazole-based curing accelerator, and a metal salt. The polymer electrolyte for dye-sensitized solar cells according to claim 1, wherein the heat-curable epoxy resin has 2 to 8 functional groups and a molecular weight of 500 to 8,000. The polymer electrolyte for dye-sensitized solar cells according to claim 1, wherein the content of the imidazole-based curing accelerator is 0.1 parts by weight per 100 parts by weight of the heat curable epoxy resin. 20 parts by weight. The polymer electrolyte for a dye-sensitized solar cell according to claim 1, wherein the metal salt is contained in an amount of from 1 part by weight to 200 parts by weight per 100 parts by weight of the heat curable epoxy resin. The polymer electrolyte for dye-sensitized solar cells according to claim 1, wherein the polymer electrolyte for the dye-sensitized solar cell has a viscosity of 10 centipoise to 8,000 centipoise. . A method for producing a module for a dye-sensitized solar cell using a polymer electrolyte for a dye-sensitized solar cell, wherein the dye sensitization is used as described in any one of claims 1 to 5 A polymer electrolyte of a solar cell, and wherein the polymer electrolyte for the dye-sensitized solar cell is used as an adhesive product between the working electrode and the opposite electrode and the final form of bonding is maintained as a solid phase. A method of manufacturing a module for a dye-sensitized solar cell using a polymer electrolyte for a dye-sensitized solar cell according to claim 6, wherein the bonding between the electrodes is a heat fusion bond. A method of manufacturing a module for a dye-sensitized solar cell using a polymer electrolyte for a dye-sensitized solar cell according to claim 6, wherein the bonding between the electrodes is a flexible substrate Continuous roll coating or continuous roll hot melt.