KR101208852B1 - A polymer electrolyte composition gelated by chemical crosslinking, a method for preparation thereof and a dye-sensitized solar cell comprising the same - Google Patents

Abstract

The present invention relates to a polymer gel electrolyte composition gelled through chemical crosslinking, a method for preparing the same, and a dye-sensitized solar cell including the same. More specifically, poly (4-vinylphenol) is used as a polymer and poly (melamine) is used as a crosslinking agent. -Co-formaldehyde) to prepare a crosslinked PVP by chemically crosslinking the polymer using methylated, and then excellent polymer gel electrolyte composition prepared by adsorbing the electrolyte solution to the crosslinked PVP, a method for preparing the same and the same It relates to a dye-sensitized solar cell comprising.

Description

A polymer electrolyte composition gelated by chemical crosslinking, a method for preparations and a dye-sensitized solar cell comprising the same}

The present invention relates to a polymer gel electrolyte composition gelled through chemical crosslinking, a method for preparing the same, and a dye-sensitized solar cell including the same. More specifically, poly (4-vinylphenol) is used as a polymer and poly (melamine) is used as a crosslinking agent. -Co-formaldehyde) to prepare a crosslinked PVP by chemically crosslinking the polymer using methylated, and then excellent polymer gel electrolyte composition prepared by adsorbing the electrolyte solution to the crosslinked PVP, a method for preparing the same and the same It relates to a dye-sensitized solar cell comprising.

Dye-Sensitized Solar Cells (DSSCs) are low cost, highly energy efficient solar cells developed using inexpensive organic dyes and nanotechnology. Such dye-sensitized solar cells can transmit visible light and can be used as it is on glass windows or automobile glass of buildings. In 1971, Professor Michael Graszel of the Swiss Federal Institute of Technology (EPFL) Department of Chemistry developed the world's first new type of dye-sensitized solar cell that produces electricity using the photosynthesis reaction principle, and Korea Electronics and Telecommunications Research Institute (ETRI) It has succeeded in making dozens of um films and electrodelizing organic dyes on 10-20 nm oxide surfaces.

Dye-sensitized solar cells work on the principle of adsorbing special dyes on the surface of titanium oxide (TiO ₂ ), a metal oxide, and generating electricity by photoelectrochemical reactions when the adsorbed special dyes absorb sunlight. As the dye, ruthenium (Ru) dye having a broad light absorption from visible to near infrared range is most commonly used, and solar cells using other organic dyes are being developed one after another.

Dye-sensitized solar cells have conversion efficiency comparable to that of silicon-based solar cells and are attracting attention as next-generation solar cells due to their low production cost. Lutein dyes are currently very expensive, but many research institutes are developing alternatives to lower their production costs, which will lower their costs.

In addition to the price aspect, it is possible to generate electricity even in cloudy weather, and electricity can be produced even when the light irradiation angle is only 10 degrees. It is possible to produce solar cells with various colors and beautiful patterns such as blue, and it is possible to produce more than two times and three times more power in the same area by producing multiple layers by stacking multiple sheets. Accordingly, dye-sensitized solar cells may be widely used for glass windows of buildings, small electrical and electronic products, and military use.

Dye-sensitized solar cells are generally transparent substrates such as fluorinated tin oxide (FTO), indium tin oxide (ITO), nanoparticle oxide semiconductor layers such as TiO ₂ and ZnO, inorganic or organic such as ruthenium A photocatalyst such as a dye, an electrolyte containing an oxidation / reduction pair, and a metal catalyst such as platinum serving as a counter electrode.

In the components of dye-sensitized solar cells, the electrolyte is divided into a liquid form and a solid form, depending on the form of the medium. In the case of liquid electrolytes, liquids such as acetonitrile are used as the medium. On the other hand, in the case of solid electrolytes, low media such as poly (ethylene oxide) (PEO), poly (propylene oxide) (PPO), poly (acrylonitrile), poly (methyl methacrylate) and poly (vinyl chloride) And a polymer electrolyte type using a polymer having a glass transition temperature and containing a polar group. Also, a polymer gel electrolyte form gelled by adding a plasticizer to the polymer or crosslinking the polymer may also be used.

The solid electrolyte has a disadvantage of showing lower energy conversion efficiency than the liquid electrolyte due to low conductivity and incomplete contact between the electrolyte and the electrode. However, in the case of the solid electrolyte, there is no leakage and volatilization of the electrolyte, and the mechanical properties are also stronger than the liquid electrolyte, thereby ensuring long-term stability. Accordingly, the efficiency of the battery is reduced, but polymer-based electrolytes, especially polymer gel-based electrolytes, which have excellent stability instead of liquid electrolytes, are frequently used.

As a conventional polymer gel-based electrolyte, thermosetting prepared by absorbing an electrolyte solution in a PAA-PEG composite obtained by mixing hydrophilic poly (acrylic acid) (PAA) and amphiphilic poly (ethylene glycol) (PEG), followed by thermosetting and gelling. Gel electrolytes have been reported (Wu et al., Adv. Mater. , 2007, 19, 4006-4011). The polymer gel electrolyte has a merit that it can absorb a large amount of electrolyte because PAA is a super absorbent resin having a 3D network structure and the micro-sized pores increase according to the molecular weight of PEG. However, the polymer gel electrolyte has a disadvantage in that the bond strength between polymer chains is weak by thermosetting, that is, forming a gel form by physical change.

Meanwhile, as another polymer gel-based electrolyte, crosslinked PVPy and PAN prepared by crosslinking poly (vinylpyridine) (PVPy) and poly (acrylonitrile) (PAN) using I (CH ₂ ) ₆ I as a crosslinking agent. Copolymers of P (VPy-co-AN) have been reported (Yuan Lin et al., Electrochim. Acta. , 2007, 52, 4858-4863). The P (VPy-co-AN) has the advantage of high energy conversion efficiency in a small amount compared to the polymer gel-based electrolyte by physical crosslinking by crosslinking through chemical crosslinking rather than crosslinking through previous physical changes. . However, the P (VPy-co-AN) is a cross-linking agent is I (CH _{2) 6} I of (CH _{2) 6} In other words, bonding between the two polymers to the hydrocarbon chain of a straight chain is to be crosslinked in such a way that the bridges between the polymer This still has the disadvantage of not being strong enough.

In view of the above, the present inventors chemically crosslink the polymer by using poly (4-vinylphenol) as a polymer and poly (melamine-co-formaldehyde) methylated as a crosslinking agent. After preparing the cross-linked PVP, by adsorbing the electrolyte solution to the cross-linked PVP not only can be prepared a polymer gel electrolyte composition with excellent stability, it can be confirmed that it can provide a stable and durable dye-sensitized solar cell using this This invention was completed.

It is an object of the present invention to provide a method for preparing a polymer gel electrolyte composition having excellent stability by adsorbing an electrolyte after chemically crosslinking a polymer.

Another object of the present invention is to provide a polymer gel electrolyte composition having excellent stability prepared by the above method.

Still another object of the present invention is to provide a dye-sensitized solar cell including the polymer gel electrolyte composition.

In order to solve the above problems, the present invention provides a method for producing a polymer gel electrolyte composition comprising the following steps.

1) crosslinking poly (4-vinylphenol) (PVP) using poly (melamine-co-formaldehyde) methylated as crosslinking agent to produce crosslinked PVP; And

2) adsorbing the electrolyte to the crosslinked PVP of the step;

In addition, the present invention may further comprise the step of adding an additive (step 3) in the above production method.

Step 1 is a step of crosslinking poly (4-vinylphenol) using poly (melamine-co-formaldehyde) methylated as a crosslinking agent to produce crosslinked PVP, which is gelled through chemical crosslinking to be electrolyte. It is a step of preparing a crosslinked polymer having a skeleton that can secure the space that can be adsorbed.

As used herein, the term "crosslinking agent" refers to a material for crosslinking molecules of a linear polymeric material to make a polymeric polymer of a net structure.

The main polymer used in the present invention is also referred to as polyvinylphenol (polyvinylphenol) as poly (4-vinylphenol) [poly (4-vinylphenol), PVP).

The crosslinking agent used in the present invention is poly (melamine-co-formaldehyde) methylated [Formula 2].

The poly (4-vinylphenol) (PVP) of Formula 1, which is a polymer used in the present invention, is chemically crosslinked through poly (melamine-co-formaldehyde) methylated compound of Formula 2 as a crosslinking agent. To provide a crosslinked PVP.

In the present invention, the reaction temperature condition of the crosslinking is preferably a temperature range of 130 ~ 160 ℃. If it is out of the temperature range, the crosslinking rate of the polymer is slow or crosslinking hardly occurs. When chemical crosslinking reaction is carried out using the above compound, the reaction temperature is a very important factor. At temperatures below 130 ° C., the desired reaction does not occur between reactants or occurs very slowly, making crosslinked polymer gels difficult. In addition, the reaction is too fast at a temperature higher than 160 ℃ can not control the degree of crosslinking reaction, most of the difficulty due to the excessive reaction to prepare the desired polymer gel.

In the present invention, the reaction time condition of the crosslinking is different depending on the reaction temperature, but 0.5 to 4 hours is preferable. If it is outside the temperature range, it is difficult to prepare the polymer gel for the electrolyte due to the slow crosslinking rate of the polymer, no crosslinking or excessive crosslinking reaction.

In the present invention, the amount of the crosslinking agent added is preferably in the range of 50 to 100 parts by weight based on 100 parts by weight of poly (4-vinylphenol) as the main polymer. If the amount is less than the lower limit, crosslinking of the main polymer does not occur sufficiently, and if the polymer gel is not formed, and if the amount is added more than the upper limit, the excess crosslinking agent remains in the reactant, making it difficult to prepare the polymer gel in a desired state.

Step 2 is a step of adsorbing the electrolyte to the cross-linked PVP of step 1, the step of adsorbing the electrolyte into the cross-linked space formed between the polymer chains.

As used herein, the term "electrolyte" refers to a material capable of being adsorbed to a crosslinked polymer in an electrolyte composition to produce a redox pair.

LiI and I ₂ , NaI and I ₂ , KI and I ₂ , CsI and I ₂ , imidazolium iodide and I ₂ may be used as the electrolyte in the present invention, but are not limited thereto. Do not.

In the present invention, the content of the electrolyte is preferably 5 to 40% by weight based on the total weight of the polymer gel electrolyte composition. If the content of the electrolyte is less than the lower limit, the polymer-based electrolyte does not have the ion conductivity required in the present dye-sensitized solar cell, and thus it is difficult to be used in practice. There is a disadvantage in that there is a possibility of leakage that is pointed out as a disadvantage of liquid electrolyte due to insufficient absorption.

Step 3 is a step of adding an additive, optionally adding a conventional additive, which can be optionally added, and may be performed if necessary or as desired.

Additives that can be added in the present invention include acetonitrile (ACN), propylene carbonate (PC), 4-tert-butyl pyridine (t-BP), guanidinium thiocyanate (guanidinium thiocyanate, GuTc), 1-methyl-3-propylimidazolium iodide (1-methyl-3-propylimidazolium iodide, PMII), valeronitrile (VN) or a combination thereof can be used.

Propylene carbonate in the present invention is an additive used as a solvent of the crosslinked polymer. The amount of propylene carbonate added is preferably 20 to 70% by weight, more preferably 57 to 62% by weight and most preferably 59.5% by weight based on the total weight of the polymer gel electrolyte composition. If the amount of the propylene carbonate is out of the above range, there is a disadvantage in that no crosslinking reaction occurs or the viscosity of the crosslinked polymer becomes too high.

4-tert-butyl pyridine in the present invention is an additive used to make the photoelectrode not directly in contact with the electrolyte. The amount of 4-tert-butyl pyridine added is preferably 3 to 10% by weight, more preferably 5.0 to 7.0% by weight and most preferably 5.86% by weight based on the total weight of the polymer gel electrolyte composition. If the amount of 4-tert-butyl pyridine added is outside the above range, there is a disadvantage in that reverse-electron transfer from the photoelectrode to the electrolyte occurs or is not effectively conducted.

In the present invention, guanidinium thiocyanate is effectively used to improve the device performance by changing the absorbance of the device by changing protons to guanidium ions in N719 dyes and changing dye molecular orbitals. It is an additive. The addition amount of guanidinium thiocyanate is preferably 0.5 to 1.5% by weight, more preferably 1.7 to 1.2% by weight and most preferably 1.02% by weight based on the total weight of the polymer gel electrolyte composition. If the addition amount of guanidinium thiocyanate is outside the above range, there is a disadvantage that the device performance is not greatly improved.

In the present invention, 1-methyl-3-propylimidazolium iodide is an additive used to form an oxidation / reduction pair together with I ₂ and to prevent reverse transfer of electrons. The amount of 1-methyl-3-propylimidazolium iodide added is preferably 15-30% by weight, more preferably 20-24% by weight, most preferably 21.8, based on the total weight of the polymer gel electrolyte composition. Weight percent. If the addition amount of 1-methyl-3-propylimidazolium iodide is out of the above range, the concentration of the oxidation / reduction pair is not appropriate and there is a disadvantage that reverse transfer of electrons may occur.

Valeronitrile in the present invention is an additive used as a solvent of a liquid electrolyte. The addition amount of valeronitrile is preferably 10 to 50% by weight, more preferably 30 to 40% by weight, most preferably 35.0% by weight based on the total weight of the polymer gel electrolyte composition. If the addition amount of valeronitrile is outside the above range, there is a disadvantage that the concentration of the electrolyte solution becomes too high or too low.

In addition, the present invention provides a polymer gel electrolyte composition having excellent stability prepared by the above method.

Furthermore, the present invention provides a dye-sensitized solar cell comprising the polymer gel electrolyte composition.

The present invention uses poly (4-vinylphenol) as a polymer and poly (melamine-co-formaldehyde) methylated as a crosslinking agent to chemically crosslink the polymer to prepare crosslinked PVP. By adsorbing the electrolyte solution to PVP, not only the polymer gel electrolyte composition having excellent stability can be prepared, but also there is an effect of providing a stable and durable dye-sensitized solar cell using the same.

1 is a photograph showing a process for preparing a polymer gel electrolyte composition of the present invention.
2 is a view illustrating a process of manufacturing a dye-sensitized solar cell using the polymer gel electrolyte composition and a state of the fabricated dye-sensitized solar cell.
3 is a graph showing the current density characteristics of the dye-sensitized solar cell including the polymer gel electrolyte composition of the present invention.
4 is a time-dependent performance of a dye-sensitized solar cell manufactured using a liquid electrolyte, that is, a change in solar cell efficiency and a time-dependent performance of a dye-sensitized solar cell manufactured using the polymer gel electrolyte composition of the present invention. It is a graph comparing the change of solar cell efficiency. However, liquid electrolyte based solar cells are devices that are sealed using surlyn tape to prevent leakage, and polymer gel electrolyte composition based solar cells are unprotected devices.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

Example 1-6 Preparation of Polymer Gel Electrolyte Composition of the Present Invention

First, 0.5 g of poly (4-vinylphenol) (PVP) was crosslinked by heating at 140 ° C. for 2 hours using 0.25 g of poly (melamine-co-formaldehyde) methylated as a crosslinking agent to crosslink PVP. Was prepared.

2.22% by weight of iodine and 1.95% by weight of lithium iodide, based on the weight of the solution after mixing as an electrolyte, were mixed in the proportions of Table 1 below, where 72.62% by weight PMII, 3.45% by weight GuTc, and An electrolyte composition was prepared by further adding 19.74% by weight of t-BP, followed by sonication for about 30 minutes to produce a uniform solution.

The polymer gel electrolyte composition of the present invention was prepared by infiltrating the electrolyte composition prepared above into the crosslinked PVP for 14 days to adsorb the electrolyte into the crosslinked PVP.

A manufacturing process of the polymer gel electrolyte composition is shown in FIG. 1.

division Electrolyte (Ion) Content Example 1 10 wt% Example 2 15 wt% Example 3 20 wt% Example 4 25 wt% Example 5 30 wt% Example 6 35 wt%

Example 7-12 Preparation of Dye-Sensitized Solar Cell Including Polymer Gel Electrolyte Composition of the Present Invention

A dye-sensitized solar cell including the polymer gel electrolyte composition of Examples 1 to 6 was prepared.

The specific manufacturing process was as follows.

As an electrode preparation process, a glass substrate on which two FTOs having a desired size were deposited was immersed in each solvent in the order of detergent-distilled water-acetone-isopropyl in ultrasonic solvent for 15 minutes to prepare a clean FTO substrate. TiO ₂ paste is printed on the cleaned FTO using a screen printer or doctor bladder to the desired area and heated in a vacuum oven at a temperature of 120 ° C for 10 minutes to solidify, and the above printing process is repeated 6 times. ₂ film was made and calcined by heating the furnace at 500 ° C for 30 minutes. After the calcination, Dye was adsorbed on the surface of TiO _{2 by} immersing in 0.05mM N-719 dissolved ethanol for one day. Another prepared FTO substrate was treated with 120W for 10 minutes using a Plasma cleaner, spin-coated H ₂ PtCl ₆ (2000RPM, 10 seconds), heated to 390 ℃ for 30 minutes in a Furnace, and reduced to Pt. A thin film was prepared.

After providing a suitable space on the FTO substrate on which the dye is adsorbed by using Surlyn tape, put the polymer gel electrolyte composition prepared above (as much as TiO ₂ is covered) and bond the FTO coated with Pt film so that the electrode surface abuts. After fixing the tongs for fixing to complete the manufacturing of the dye-sensitized solar cell.

Experimental Example 1: Investigation of the current density characteristics of the dye-sensitized solar cell comprising the polymer gel electrolyte composition of the present invention

The current density characteristics of the dye-sensitized solar cells prepared in Examples 7 to 12 were investigated.

The measurement of the current density was specifically performed as follows.

The reference cell was first connected to the solar simulator, and the light quantity was adjusted to 1sun state (10mW / cm). After installing the solar cell perpendicular to the light source of the solar simulator adjusted in this way, the current was measured by applying a voltage from 0V to 1V. The current density was measured by dividing the area by the measured value.

The measurement results are shown in FIG. 2.

2 shows that the polymer gel electrolyte composition of the present invention has excellent current density characteristics.

Experimental Example 2: Investigation of the performance change of the dye-sensitized solar cell comprising the polymer gel electrolyte composition of the present invention

Since the performance change with time of the dye-sensitized solar cell including the polymer gel electrolyte composition is an important factor, in the present experimental example, the performance (solar cell efficiency) change with time of the dye-sensitized solar cell manufactured using the conventional liquid electrolyte was It was compared with the performance (solar cell efficiency) change with time of the dye-sensitized solar cell using the polymer gel electrolyte composition of the present invention prepared in Example 5.

Experimental method was used the method used in Experimental Example 1, and compared the characteristics of the solar cell over time and shown in FIG. However, for comparison with the polymer gel-based electrolyte composition prepared in the present invention, the liquid electrolyte-based solar cell prevented leakage, which is the biggest disadvantage of the liquid electrolyte-based solar cell device by sealing the device using a surlyn tape. . However, the polymer gel electrolyte composition invented in the present invention has almost no flow unlike the liquid electrolyte, and thus the properties of the polymer gel electrolyte were investigated without changing the characteristics of the polymer gel electrolyte.

Claims (10)

Method for producing a polymer gel electrolyte composition comprising the following steps:
1) crosslinking poly (4-vinylphenol) (PVP) using poly (melamine-co-formaldehyde) methylated as crosslinking agent to produce crosslinked PVP; And
2) adsorbing the electrolyte to the crosslinked PVP of the step;
3) Acetonitrile, propylene carbonate, 4-tert-butyl pyridine, guanidinium thiocyanate, 1-methyl-3-propylimidazolium iodide, valeronitrile or combinations thereof Method for producing a polymer gel electrolyte composition further comprising the step of adding an additive.
According to claim 1, wherein the reaction temperature of the crosslinking method of producing a polymer gel electrolyte composition is a temperature range of 130 ~ 160 ℃.
The method of claim 1, wherein the reaction time of the crosslinking is 0.5 hours to 4 hours.
The method of claim 1, wherein the amount of the crosslinking agent added is 50 to 100 parts by weight based on 100 parts by weight of poly (4-vinylphenol).
The method of claim 1, wherein the electrolyte comprises: i) LiI and I ₂ , ii) NaI and I ₂ , i) KI and I ₂ , i) CsI and I ₂ , Or iii) a method for producing a polymer gel electrolyte composition which is imidazolium iodide and I ₂ .
The method of claim 1, wherein the content of the electrolyte is 5 to 40% by weight based on the total weight of the polymer gel electrolyte composition.
delete A polymer gel electrolyte composition prepared by the method of any one of claims 1 to 7.
A dye-sensitized solar cell comprising the polymer gel electrolyte composition of claim 9.

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