JP2014146436A - Dye-sensitized solar cell and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure of excellent power generation efficiency by preventing bubbles, derived from air in the electrolyte in a tubular container, from remaining thereby preventing a sensitizing dye from desorbing from a photoelectrode, in a dye-sensitized solar cell where a photoelectrode, a collector electrode and a counter electrode are provided in a translucent tubular container having sealing portions at both ends, and an electrolytic solution is filled in the tubular container.SOLUTION: At both sealing portions, there are provided a first metal tube and a second metal tube, each extending from the inside to the outside of a tubular container. The first metal tube is connected electrically to a counter electrode, and the second metal tube is connected electrically to a collector electrode. The first and second metal tubes have sealed ends projecting from the tubular container, and bubbles of an inert gas are left in the electrolyte.

Description

  The present invention relates to a dye-sensitized solar cell that converts light energy into electric energy, and more particularly to a dye-sensitized solar cell in which an electrolyte is enclosed in a translucent tubular container. .

  Conventionally, solar cells that convert solar energy into electrical energy have been actively researched and developed as environmentally friendly and clean energy sources. Among them, a dye-sensitized solar cell has attracted attention as a low-cost solar cell with high photoelectric conversion efficiency, and various proposals have been made.

One example is Japanese Patent No. 4840540 (Patent Document 1). In this dye-sensitized solar cell, a porous material in which an electrolytic solution is sealed in a translucent tubular container and the dye is adsorbed in the container. A photoelectrode made of a semiconductor and a counter electrode facing the photoelectrode are arranged, and sunlight is made incident on the photoelectrode to excite it to emit electrons, thereby taking out it as electric energy.
This type of dye-sensitized solar cell is attracting attention because it does not require a high-vacuum chamber or the like for its manufacture, has a small burden on facilities, and can be manufactured at low cost.

The schematic structure of the solar cell of the structure concerning FIG. 5 is shown, (A) is the sealing process figure of electrolyte solution, (B) is a sealing completion figure.
In the figure, a dye-sensitized solar cell includes a collector electrode 3 made of a transparent conductive film and a photoelectrode made of a semiconductor layer in which a sensitizing dye is adsorbed on the inner surface of a main body 2 of a tubular container 1 made of transparent glass. 4 is laminated, and a coiled counter electrode 5 is disposed in the tubular container 1 so as to be separated from the photoelectrode 4, and an electrolytic solution 6 including an electrolyte substance is sealed in the tubular container 1. It is configured.
Both ends of the main body portion 2 of the tubular container 1 are sealed by forming flat sealing portions 21 and 22 by heating and melting glass constituting the tubular container 1 and crushing the glass. A metal foil 31 is embedded in the sealing portion 21 on one end side, and the internal lead 11 from the counter electrode 5 and the external lead 13 protruding outward from the sealing portion 21 are attached to the metal foil 31. Connected to provide a conductive state.
Similarly, a metal foil 32 is embedded in the sealing portion 22 on the other end side, and the internal lead 12 connected to the counter electrode 5 via the insulating member 15 is connected to the metal foil 32. The external lead 14 protruding from the sealing portion 22 is connected. And the collector electrode 3 formed in the inner surface of the main-body part 2 of the said tubular container 1 is extended in this sealing part 22, and covers the said internal lead 12, the metal foil 32, and the external lead 14 It is pinched and electrically connected to these.

  With such a configuration, in one sealing part 31, electrical connection is formed with the counter electrode 5-internal lead 11-metal foil 31-external lead 13, and in the other sealing part 32, the photoelectrode 4 is formed. The collector electrode 3 -the internal lead 12 -the metal foil 32 -the external lead 14 and the electrical connection are formed.

A process of encapsulating the electrolytic solution 6 in the tubular container 1 formed in this way will be described.
As shown in FIG. 5 (A), in the cylindrical main body 2 of the tubular container 1, an injection tube 23 is welded to an end region where the collector electrode 3 and the photoelectrode 4 are not formed on the inner surface. Communicating with the inside.
The electrolytic solution 6 is injected into the tubular container 1 from the injection tube 23. After the electrolytic solution 6 is filled in the tubular container 1, the injection tube 23 is melted and sealed. With this melt-sealed tube, as shown in FIG. 5B, a sealing chip remaining portion 23 a is formed in the main body portion 2 of the tubular container 1.

By the way, according to the above-described prior art, when the injection tube 23 is sealed by heating and melting, it is inevitable that gases such as oxygen and hydrogen derived from the atmosphere are mixed in the tubular container 1, and electrolysis in the tubular container 1 is avoided. Bubbles Y made of the atmosphere-derived gas remain in the liquid 6.
The sensitizing dye adsorbed on the photoelectrode 4 may react with oxygen or water in the air to hydrolyze and be detached from the photoelectrode. Therefore, if the bubbles Y made of the above-mentioned gas derived from the atmosphere remain in the electrolytic solution 6 in the tubular container 1, the sensitizing dye is detached from the photoelectrode 4 and the power generation efficiency is remarkably deteriorated. There's a problem.

Japanese Patent No. 4840540

  In view of the above-mentioned problems of the prior art, the problem to be solved by the present invention is a photoelectrode comprising a semiconductor layer carrying a sensitizing dye inside a tubular container having sealing portions at both ends, and the photoelectrode In a dye-sensitized solar cell comprising a collector electrode formed in contact with the collector electrode and a counter electrode facing the collector electrode, the tubular container being filled with an electrolyte solution, and enclosed in the tubular container The present invention provides a dye-sensitized solar cell and a method for producing the same, in which air-derived air bubbles do not remain in the electrolyte solution and the sensitizing dye is prevented from being detached from the photoelectrode.

In order to solve the above-described problems, in the dye-sensitized solar cell according to the present invention, the sealing portions at both ends of the tubular container each include a first metal tube and a second metal tube extending from the inside of the tubular container to the outside. A metal tube is provided, the first metal tube is electrically connected to the counter electrode, and the second metal tube is electrically connected to the collector electrode. The metal tube is sealed at the end protruding from the tubular container, and bubbles of an inert gas remain in the electrolyte.
In addition, the bubbles made of the inert gas have a volume ratio of 5% or less of the inner volume of the tubular container.
Further, the counter electrode and the first metal tube are formed of the same tube member.

  Furthermore, in the method for producing a dye-sensitized solar cell according to claim 1, the first step of sealing the projecting end of one of the metal tubes to block communication between the inside and the outside of the tubular container; A second step of exhausting the gas inside the tubular container through the other metal tube, and an inert gas is sealed in the tubular container through the other metal tube while maintaining a negative pressure state. A third step, a fourth step of pressing and sealing the protruding end of the other metal tube, and a fifth step of introducing the electrolyte into the tubular container via the one metal tube. And a sixth step of sealing the projecting end of the one metal tube after the electrolyte solution is filled, and the inert gas bubbles are left inside the tubular container. It is characterized by filling with an electrolytic solution.

  According to the dye-sensitized solar cell of the present invention, exhausting the inside of the tubular container, enclosing the inert gas, and injecting the electrolyte solution through the metal tubes provided at the sealing portions at both ends of the tubular container. Therefore, the air bubbles made of an inert gas remain in the filled electrolyte solution, so that bubbles originating from the atmosphere do not remain in the electrolyte solution, and the sensitizing dye is removed from the photoelectrode. Is prevented, and a dye-sensitized solar cell with good power generation efficiency can be obtained.

Sectional drawing of the dye-sensitized solar cell of this invention. Sectional drawing of the other Example of this invention. The manufacturing process figure of the dye-sensitized solar cell of this invention. The graph which shows the relationship between the inert gas bubble and power generation efficiency in this invention. Sectional drawing of the dye-sensitized solar cell which concerns on a prior art.

FIG. 1 is a cross-sectional view showing the entirety of the dye-sensitized solar cell of the present invention, in which (A) is a side cross-sectional view and (B) is an AA cross-sectional view thereof.
A collector electrode 3 made of a transparent conductive film and a photoelectrode 4 laminated thereon are provided on the inner surface of the main body 2 of the tubular container 1. A cylindrical counter electrode 5 is disposed in the main body portion 2 of the tubular container 1 at a predetermined interval without coming into contact with the photoelectrode 4.
The tubular container 1 is filled with an electrolytic solution 6.
The counter electrode 5 is not limited to a cylindrical body, and various forms such as a rod-shaped body and a coil-shaped body can be adopted.

The first metal tube 7 is sealed in one sealing portion 21 of the tubular container 1, and the second metal tube 8 is sealed in the other sealing portion 22. The metal pipes 7 and 8 are sealed by using a shrink seal technique in the lamp manufacturing technique. The glass constituting the sealing parts 21 and 22 is heated and melted and welded to the metal pipes 7 and 8. It has been stopped.
Then, one end of the counter electrode 5 is connected to the first metal tube 7, and the collector electrode 3 is connected to the second metal tube 8 through the connection terminal 9, thereby being electrically connected to each other. .
The metal tubes 7 and 8 project outside through the sealing portions 21 and 22, respectively, and the projecting end portions 7a and 8a are sealed by pressure contact or the like.
The tubular container 1 sealed in this way is filled with the electrolytic solution 6, and bubbles X made of an inert gas remain therein.

  FIG. 2 shows another embodiment, in which the counter electrode 5 in the tubular container 1 and the first metal tube 7 are made of the same tube member. In addition, about another structure, it is the same as that of the aspect shown in FIG.

A method for producing the dye-sensitized solar cell will be described with reference to FIG.
First, a first metal tube 7 connected to the counter electrode 5 disposed in the tubular container 1 and a second metal connected to the collector electrode 3 formed on the inner surface of the tubular container 1 together with the photoelectrode 4. A solar cell structure M sealed by a so-called shrink seal method is prepared in which the tube 8 is heated and melted by sealing the sealing portions 21 and 22 of the glass tubular container 1 and welded to the metal tubes 7 and 8.
Next, as shown in FIG. 3A, a vacuum device V and an inert gas cylinder G are connected to the end of the first metal tube 7 via gate valves A and B, respectively. On the other hand, the electrolytic solution tank L is connected to the protruding end portion of the second metal tube 8 via the gate valve C (first step).
Here, the valve B and the valve C are closed, the communication between the tubular container 1, the gas cylinder G and the electrolyte tank L is cut off, the valve A is opened, and the impure gas such as air in the tubular container 1 is removed by the vacuum device V. Evacuate to a vacuum state (second step). In this case, it is preferable to perform so-called warm evacuation, in which the tubular container 1 is heated and evacuated to evaporate unnecessary substances (impurities including water) attached to the inner wall of the tubular container 1.
Next, when the valve A is closed and the valve B is opened, the inert gas from the inert gas cylinder G is sucked into the tubular container 1 and introduced. At this time, the inert gas is introduced to such an extent that the inside of the tubular container 1 is maintained in a negative pressure state (third step).

Next, as shown in FIG. 3B, the protruding end portion 7a of the first metal tube 7 is pressed and sealed by the press machine P (fourth step).
Next, as shown in FIG. 3C, the valve C is opened and the electrolytic solution 6 is introduced from the electrolytic solution tank L using the negative pressure state in the tubular container 1 (fifth step).
Then, as shown in FIG. 3D, after the electrolytic solution 6 is filled to such an extent that the inert gas bubbles X remain in the tubular container 1, the second metal tube 8 is pressed by the press machine P. The protruding end portion 8a is sealed by pressure contact (sixth step).
Through the above steps, the dye-sensitized solar cell filled with the electrolytic solution 6 with the inert gas bubbles X remaining in the tubular container 1 is completed.

In the above description, the second metal tube 8 connected to the collector electrode 3 is exhausted from the first metal tube 7 connected to the counter electrode 5, introduced with an inert gas, sealed. In contrast to this, the electrolyte solution 6 is introduced from the second metal tube 8, but the exhaust gas is exhausted from the second metal tube 8, an inert gas is introduced, and the electrolyte solution 6 is introduced from the first metal tube 7. It may be.
Further, the solar cell structure M may be installed vertically to introduce exhaust / inert gas and introduce electrolyte.

In the above configuration, the tubular container 1 is a translucent glass member and is sealed to the metal tubes 7 and 8 by thermal welding. Therefore, it is preferable that the glass and the metal tube are materials having a close linear expansion coefficient. Specifically, a combination in which the difference in linear expansion coefficient α is within a range of ± 5 × 10 ⁻⁷ / ° C. is preferable. Examples of such combinations are listed below.
(Example 1)
Tubular container: aluminosilicate glass (linear expansion coefficient α = 51 × 10 ⁻⁷ / ° C.)
Metal pipe: Molybdenum pipe (linear expansion coefficient α = 55 × 10 ⁻⁷ / ° C.)
(Example 2)
Tubular container: Kovar glass (linear expansion coefficient α = 55 × 10 ⁻⁷ / ° C.)
Metal tube: Kovar pipe (linear expansion coefficient α = 50 × 10 ⁻⁷ / ° C.)
(Example 3)
Tubular container: soda lime glass (linear expansion coefficient α = 90 × 10 ⁻⁷ / ° C.)
Metal pipe: Titanium pipe (linear expansion coefficient α = 88 × 10 ⁻⁷ / ° C.)

The metal tubes 7 and 8 are suitably made of a material having high corrosion resistance against the electrolyte solution 6. For example, when the electrolyte contains iodine having high reactivity with a metal, it is preferable to use a titanium member or a member whose surface is coated with titanium for the metal tube.
That is, in the above combination example, it is preferable that the metal tubes of Examples 1 and 2 are titanium-coated. For example, it is preferable to prepare a molybdenum pipe and perform titanium coating on the surface with a film thickness of about several tens of nanometers by sputtering.

By the way, if the ratio of the inert gas bubbles X remaining in the tubular container 1 to the electrolytic solution 6 is too large, the power generation efficiency of the solar cell tends to deteriorate. This is because the bubbles X hinder the transfer of electrons from the counter electrode 5 to the collector electrode 4. However, when the ratio of the bubbles X is small, the power generation efficiency is not significantly deteriorated. The inventor has confirmed that if the volume ratio of bubbles to the internal volume (effective volume) of the tubular container 1 is 5% or less, the power generation efficiency can be prevented from remarkably deteriorating.
At this time, since the internal pressure and internal volume of the tubular container 1 after filling with the inert gas and the bubble volume in the electrolytic solution under atmospheric pressure follow Boyle's law, the ratio of the bubbles is adjusted by the amount of the inert gas to be introduced. can do. That is, it is possible to adjust the residual bubbles X in the tubular container 1 to a desired volume ratio.

Therefore, the correlation between the residual bubbles X made of an inert gas with respect to the tubular container 1 and the power generation efficiency was verified. The result is shown in FIG.
The change of the power generation efficiency with respect to the ratio of the volume of the bubbles to the effective internal volume of the tubular container 1 is seen. As described above, the volume of the bubbles is adjusted by the gas partial pressure of the inert gas.
The power generation efficiency (η) is a measured value of open circuit voltage (Voc), short circuit current (Isc) and fill factor (FF) generated in the battery when the dye-sensitized solar cell is irradiated with light. From this, it is calculated by the following formula.
η = Isc × Voc × FF
The measurement result shown in FIG. 4 is obtained by measuring the power generation efficiency when a xenon lamp (AM1.5 = 100 mW / cm ² ) is used as pseudo-sunlight and the lamp is irradiated with light. Moreover, this measurement was implemented 3 times according to conditions in the state where the tube axis direction of the solar cell was arranged horizontally with respect to the ground, and an average value thereof was adopted as a measurement value.

  As shown in FIG. 4, the power generation efficiency decreases as the ratio of bubbles in the inner volume of the tubular container increases. However, the degree of reduction in power generation efficiency is not constant with respect to the ratio of bubbles, and particularly when the ratio of bubbles is 5% or less, the rate of decrease in power generation efficiency is very slight and remains from the viewpoint of power generation efficiency. Problems caused by bubbles are not a practical problem.

As described above, according to the dye-sensitized solar cell of the present invention, the light electrode, the collector electrode, and the counter electrode are provided inside the translucent tubular container having the sealing portions at both ends. In the dye-sensitized solar cell in which the inside of the tubular container is filled with an electrolytic solution, the sealing portions at both ends are electrically connected to the counter electrode extending from the inside of the tubular container to the outside, respectively. A first metal tube and a second metal tube electrically connected to the collector electrode, and the first and second metal tubes have end portions protruding from the tubular container. Air bubbles made of inert gas remain in the electrolyte solution so that bubbles derived from air do not remain in the tubular container and sensitize from the photoelectrode. Dye sensitized type that prevents dye from detaching and has good power generation efficiency The battery can be obtained.
Furthermore, since solar cells are exposed to sunlight for a long time, the temperature tends to increase, and the electrolyte filled in the tubular container expands, and the liquid pressure inside the container increases and the container is likely to be loaded. By including bubbles in the electrolytic solution, the bubbles serve as a buffer region for the hydraulic pressure, and there is an effect of reducing the load on the tubular container.

DESCRIPTION OF SYMBOLS 1 Tubular container 2 Main-body part 21 and 22 Sealing part 3 Collector electrode 4 Photoelectrode 5 Counter electrode 6 Electrolyte solution 7 and 8 Metal tube 9 Connection terminal M Solar cell structure V Vacuum apparatus G Inert gas cylinder L Electrolyte tank A, B, C Gate valve

Claims (4)

A translucent tubular container having sealing portions at both ends, a photoelectrode formed of a semiconductor layer carrying a sensitizing dye inside the tubular container, and a collecting electrode formed in contact with the photoelectrode A dye-sensitized solar cell comprising a counter electrode facing the collector electrode, and an electrolyte solution filled in the tubular container.
The sealing portions at both ends are provided with a first metal tube and a second metal tube respectively extending from the inside of the tubular container to the outside,
The first metal tube is electrically connected to the counter electrode, and the second metal tube is electrically connected to the collector electrode;
The first and second metal tubes are sealed at the ends protruding from the tubular container,
A dye-sensitized solar cell, wherein bubbles of an inert gas remain in the electrolytic solution.   2. The dye-sensitized solar cell according to claim 1, wherein the bubbles made of the inert gas have a volume ratio of 5% or less of the inner volume of the tubular container.   The dye-sensitized solar cell according to claim 1 or 2, wherein the counter electrode and the first metal tube are made of the same tube member. A method for producing a dye-sensitized solar cell according to claim 1,
A first step of sealing the projecting end of the one metal tube to block communication between the inside and outside of the tubular container;
A second step of exhausting the gas inside the tubular container through the other metal tube;
A third step of enclosing an inert gas while maintaining a negative pressure state in the tubular container via the other metal tube;
A fourth step of pressing and sealing the protruding end of the other metal tube;
A fifth step of introducing the electrolytic solution into the tubular container through the one metal tube;
A sixth step of sealing the protruding end of the one metal tube after the electrolyte is filled;
Thus, the method for producing a dye-sensitized solar cell is characterized in that the electrolytic solution is filled in a state where inert gas bubbles remain inside the tubular container.

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