KR20130080143A

KR20130080143A - Grid electrode structure of dye-sensitized solar cell

Info

Publication number: KR20130080143A
Application number: KR1020120000907A
Authority: KR
Inventors: 오광진
Original assignee: 주식회사 세아 이앤티
Priority date: 2012-01-04
Filing date: 2012-01-04
Publication date: 2013-07-12

Abstract

PURPOSE: A grid electrode structure of a dye-sensitized solar cell is provided to improve photoelectric conversion efficiency by widening a second grid electrode in comparison to a first grid electrode to reduce resistance. CONSTITUTION: A collection electrode (320) connects excited electrons from dye to an external electric circuit. A grid electrode is composed of two second grid electrodes (342) and nine first grid electrodes (341). The first grid electrode is horizontally separated from the collection electrode. The second grid electrode is electrically connected to the collection electrode. The second grid electrode is wider than the first grid electrode.

Description

Grid electrode structure of dye-sensitized solar cell {GRID ELECTRODE STRUCTURE OF DYE-SENSITIZED SOLAR CELL}

The present invention relates to a grid electrode structure of a dye-sensitized solar cell.

Dye-Sensitized Solar Cell (DSSC) is a solar cell developed by Michael Gratzel of the Swiss Federal Institute of Technology. It has lower manufacturing cost compared to conventional silicon solar cells, It is possible to manufacture a cell which is high in transparency and bendability and thus can be used in various applications.

Dye-sensitized solar cells serve as catalysts for photoelectrodes containing dye molecules that produce electron-hole pairs and semiconductor layers that deliver the generated electrons, electrolytes that supplement electrons with dye molecules, and redox reactions of electrolyte solutions. Made of a counter electrode coated with a platinum layer. When light is incident on the dye-sensitized solar cell, the dye that absorbs the light enters an excited state to send electrons to the conduction band of the semiconductor layer, and the transferred electrons flow along the electrode to an external circuit to transfer electrical energy. As it transfers electrical energy, it becomes a low energy state and moves to the counter electrode. The dye is supplied with electrons from the electrolyte solution as much as the number of electrons transferred to the semiconductor layer and returned to its original state. The electrolyte used serves to receive electrons from the counter electrode by a redox reaction and transfer them to the dye. The photoelectrode serving as a negative electrode of a dye-sensitized solar cell includes a semiconductor layer, such as titanium dioxide (TiO ₂ ), on which a dye, which absorbs light in the visible region, generates an electron-hole pair. Electrolyte supplying electrons to dye is I ^- / I ₃ ^- consists of a reduced species, I ^- - oxidation as a source of ions LiI, NaI, alkaline ammonium iodide, imidazolium iodide, etc. are used, I ₃ ^- ions to produce an I ₂ melt in a solvent. The counter electrode is made of platinum or the like and serves as a catalyst for the ion redox reaction to provide electrons to ions in the electrolyte through a redox reaction on the surface.

Fluorine doped tin oxide (FTO) is widely used as a transparent electrode constituting the photoelectrode or counter electrode of a dye-sensitized solar cell. Since the fluorine dopant tin oxide has a higher electrical resistance than a metal material, a grid electrode for collecting electrons may be further formed on the transparent electrode. In addition, a collecting electrode for connecting grid electrodes to each other is required to configure a solar cell module by connecting solar cells of a unit cell in parallel or in addition to a function of accumulating electrons. Silver (Ag) may be used as the grid electrode material. When silver is in direct contact with the electrolyte, silver may be oxidized by the electrolyte to lose the original function of the grid electrode. By-products generated by the oxidation reaction may be included in the electrolyte. Power generation efficiency may also be reduced. Therefore, in order to protect the grid electrode from the electrolyte, the surface of the metal electrode should be sealed with a sealing material such as surlyn.

1 illustrates a grid electrode of a dye-sensitized solar cell. Referring to FIG. 1, current collecting electrodes 113 and 123 are formed on the photoelectrode substrate and the counter electrode substrate of the dye-sensitized solar cell 100, and the plurality of grid electrodes 113a, 123a) is connected.

FIG. 2 is a cross-sectional view of the dye-sensitized solar cell to which the grid electrode is applied (AA 'direction cross-section of FIG. 1). Referring to FIG. 2, the photoelectrode substrate 110 and the counter electrode substrate 120 are opposed to each other and sealed by the sealing member 115 to fill the space between the substrates and the electrolyte 116. The transparent electrodes 111 and FTO are formed on the photoelectrode substrate 110, the semiconductor oxide layer 112 is formed on the transparent electrode 111, and the grid electrode 113a is formed in the middle. A protective layer 114 is formed on the grid electrode 113a to prevent direct contact between the electrolyte and the grid electrode 113a. The transparent electrode 121 and the platinum layer 122 are sequentially stacked below the counter electrode substrate 120, and the grid electrode 123a and the protective layer 124 are also formed on the transparent electrode 121 of the counter electrode substrate. When the external electrical circuit is connected, the electron transfer path in the dye-sensitized solar cell including the grid electrode allows electrons excited from the dye to sequentially move to the current collecting electrode and supply electricity through the semiconductor layer, the transparent electrode, and the grid electrode. do.

Here, the electrons excited from the dye have a problem that the photoelectric conversion efficiency of the dye-sensitized solar cell is lowered as the electron transfer to the grid electrode is delayed as the resistance moves through the transparent electrode having a relatively larger size than the grid electrode.

Therefore, there is a need for a new grid electrode structure of a dye-sensitized solar cell that can quickly move electrons excited from the dye to the grid electrode by minimizing the path of migration on the transparent electrode.

The present invention has been made to solve the above-described problems, an object of the present invention is to minimize the distance that the electrons excited from the dye reaches the grid electrode and at the same time can reduce the resistance when moving from the grid electrode to the current collector electrode It is to provide a grid electrode structure of a dye-sensitized solar cell.

In order to solve the above problems, the grid electrode structure of the dye-sensitized solar cell of an embodiment of the present invention is a collector electrode for connecting the electrons excited from the dye to an external electrical circuit, at least one formed in the horizontal direction with the collector electrode And a second grid electrode intersecting with the first grid electrode and the first grid electrode, wherein at least one side is formed in a vertical direction so that one side thereof is electrically connected to the current collecting electrode.

According to one embodiment of the present invention, the aperture ratio is kept constant by adjusting the widths of the first grid electrode and the second grid electrode.

According to one embodiment of the present invention, the width of the second grid electrode is characterized in that it is wider than the width of the first grid electrode.

According to an aspect of an embodiment of the present invention, the width of the second grid electrode is characterized in that it gradually widens as it moves toward the current collecting electrode at a portion far from the current collecting electrode.

According to one embodiment of the present invention, the current collecting electrode is electrically connected to an external electrode, the external electrode is characterized in that formed by applying a silver paste on the side of the substrate.

According to the present invention as described above, while maintaining the same opening ratio (effective area) per unit area in the prior art, electrons excited from the dye are formed in the shortest path by forming a second grid electrode on the transparent electrode that intersects the first grid electrode perpendicularly. As the first grid electrode or the second grid electrode reaches, the electron transfer is quickly performed to the current collecting electrode, thereby improving the photoelectric conversion efficiency.

In addition, the width of the second grid electrode is formed to be wider than the width of the first grid electrode to reduce the resistance, so that electrons collected by the first grid electrode are quickly transferred to the current collecting electrode through the second grid electrode, thereby improving photoelectric conversion efficiency. There is an effect that can be improved.

1 illustrates a metal grid electrode of a dye-sensitized solar cell.
2 shows a cross section of a dye-sensitized solar cell to which a grid electrode is applied.
3A and 3B are diagrams for comparing the aperture ratio between a conventional grid electrode structure and a grid electrode structure according to the present invention.
4 is a plan view of a grid electrode structure of a dye-sensitized solar cell according to another embodiment of the present invention.
5 is a cross-sectional view of the grid electrode structure of the dye-sensitized solar cell according to an embodiment of the present invention.
6 illustrates a module of a dye-sensitized solar cell by serial or parallel connection between unit cells according to an embodiment of the present invention.
7 is a plan view of a grid electrode structure of a dye-sensitized solar cell according to another embodiment of the present invention.

The following detailed description is only illustrative, and merely illustrates embodiments of the present invention. In addition, the principles and concepts of the present invention are provided for the purpose of explanation and most useful.

Accordingly, various forms that can be implemented by those of ordinary skill in the art, as well as not intended to provide a detailed structure beyond the basic understanding of the present invention through the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The grid electrode may be formed in a predetermined pattern on the transparent electrode formed on the photoelectrode substrate and the counter electrode substrate. Herein, when light is absorbed by the dye molecules adsorbed on the semiconductor oxide layer, electrons are excited, and then the excited electrons move to the current collecting electrode through the semiconductor oxide layer and the transparent electrode. At this time, since the excited electrons are moved to the current collecting electrode along the grid electrode having a much lower electrical resistance than the transparent electrode made of a conductive oxide (ITO or FTO), the electron transfer is faster, thereby improving the efficiency of the dye-sensitized solar cell. Hereinafter, the grid electrode of the present invention may be formed with at least one protective layer that can prevent the corrosion by the penetration of the electrolyte to the outside. The grid electrode formation on the counter electrode substrate according to the present invention corresponds to the grid electrode formation on the photoelectrode substrate and thus will be omitted. In addition, the method of forming the semiconductor oxide layer, the catalyst layer and the sealing member of the dye-sensitized solar cell unit cell is obvious to those skilled in the art and will be omitted below.

3A and 3B are diagrams for comparing the aperture ratio (effective area) between the conventional grid electrode structure and the grid electrode structure according to the present invention.

As shown in FIG. 3A, a semiconductor oxide layer in which dye is adsorbed between the plurality of grid electrodes 310 and the grid electrodes 310 in a direction perpendicular to the current collecting electrode 320 on the photoelectrode unit cell 300 ( 330 is formed. The aperture ratio (effective area) is a ratio of the area of light received per unit area to affect photoelectric conversion efficiency in dye-sensitized solar cells.

Opening ratio = (unit area-total area of grid electrode) / unit area

= 1- (xyN ₁ / AB).

Where x: grid electrode width, y: the length (A = B) of one side: the grid electrode length, N _1: number of the grid electrodes, A and B.

Here, if the unit area A * B is the same, the aperture ratio depends on the grid electrode area. If the grid electrode in the dye-sensitized solar cell, the length (y) and width (x) is N ₁ gaeil grid electrode area is calculated as x * y * N _1. In FIG. 3A, six grid electrodes 610 are connected to the current collecting electrodes 320, and the total area of the grid electrodes is calculated as 6xy. On the other hand the electrons (10) from where the dye is because the distance up to the distance D ₁ between the distance between the grid electrode to relatively move the resistance is a very large transparent electrode 381 than the grid electrode 310, the D _1/2.

Next, when the aperture ratio of FIG. 3B having the grid electrode structure of the present invention is compared with that of FIG. 3A, it is only necessary to determine whether the entire area of the grid electrode formed as described above is the same.

As shown in FIG. 3B, first, the grid electrode structure formed in the photoelectrode unit cell 300 has a first grid electrode 341 and the first grid formed at predetermined intervals in the horizontal direction with respect to the current collecting electrode 320. The second grid electrode 320 intersects the electrodes 341 and is connected to the current collecting electrode 320 in a vertical direction.

First, in FIG. 3B, the grid electrode includes two second grid electrodes 342 having a width 3x / 2 and a length y and nine first grid electrodes having a width x / 3 and a length y. 341), the total area of the grid electrode is calculated as 6xy as the area of the second grid electrode (3x / 2 * y * 2) + the area of the first grid electrode (x / 3 * y * 9).

By the above calculation, since the total area 6xy of the grid electrode is the same in the same unit area (AB) in Figures 3a and 3b, it can be seen that the aperture ratio of the dye-sensitized solar cell is the same in Figures 3a and 3b.

Meanwhile, since the number of grid electrodes (6) of FIG. 3A disposed at the same distance A or B is smaller than the number of first grid electrodes (9) of FIG. 3B, the distance D ₂ between the grid electrodes in FIG. It is smaller than the distance D ₁ between the grid electrodes of FIG. 3A. Thus relatively E 10, the resistance is very large transparent electrode 381, here from electromigration distance dyes in Figure 3b is smaller than D _2/2 of Figure 3a to D _1/2 to move the image than the grid electrode is a It may move to the current collecting electrode 320 faster than the electron of 3a.

The rapid transfer of electrons can be interpreted as a decrease in the probability of electron recombination occurring when electrons excited from the dye pass through the semiconductor oxide layer and the transparent electrode, thereby increasing the photoelectric conversion efficiency. do.

Meanwhile, in the grid electrode structure according to the present invention, the second grid electrode 342 may be formed larger than the width of the first grid electrode 341. The function of the second grid electrode 342 is a passage for transferring electrons collected through the first grid electrode 341 to the current collecting electrode 320 when an external electric circuit is connected. Therefore, it is important to lower the resistance because it should have a longer length than the first grid electrode 341 and serve as a path for more electrons, which is why the width of the second grid electrode 342 is the width of the first grid electrode 341. It can be made by forming a wider than.

4 is a plan view of a grid electrode structure of a dye-sensitized solar cell according to another embodiment of the present invention.

As shown in FIG. 4, the grid electrode structure may be formed by crossing the first grid electrode 341 and the second grid electrode 342 having variously modified widths according to the number of grid electrodes of FIG. 3B. . For example, when the number of grid electrodes in FIG. 3B is ten, the total area of the grid electrodes is defined as 10xy. In FIG. 4, when the number of grid electrodes is ten, eleven first grid electrodes 341 having a width (x / 2) and three second grid electrodes having a width (3x / 2) having the same grid electrode total area. 342 can be formed. Here, the total area of the grid electrode is 10xy, which is the sum of the area of the second grid electrode (3x / 2 * y * 3) and the area of the first grid electrode (x / 2 * y * 11). In this case, since the total area of the grid electrode is the same as 10xy, it can be seen that the aperture ratio of the dye-sensitized solar cell is the same.

It can be seen that the distance between the grid electrodes in FIG. 4 is D ₃ , which is smaller than the distance between the grid electrodes when the number of grid electrodes in FIG. 3B is 10, from which the electrons 10 excited from the dye move on the transparent electrode. Since the distance is minimal, it can be delivered faster to the current collecting electrode.

In addition, the width of the second grid electrode 342 in FIG. 4 may be larger than that of the first grid electrode 341. The reason for this is described in FIG. 3B and will be omitted.

The grid electrode structure according to the present invention is not limited to the number of first grid electrodes and the number of second grid electrodes, and is variously modified according to a process applied in a dye-sensitized solar cell capable of minimizing the width of the first grid electrode. Can be.

5 is a cross-sectional view (a-a 'direction) of a grid electrode structure of a dye-sensitized solar cell according to an embodiment of the present invention.

As shown in FIG. 5, the unit cell 1000 of the dye-sensitized solar cell includes a photoelectrode unit cell including a transparent electrode 381, a grid electrode 342, and a semiconductor oxide layer (not shown) on a substrate 380. And a counter electrode unit cell corresponding to the photoelectrode unit cell and including a transparent electrode 382, a grid electrode 352, and a catalyst layer (not shown) on the substrate by the sealing material 500, followed by electrolyte injection. Can be formed.

In this case, the dye-sensitized solar cell unit cell 1000 may be formed by connecting external electrodes 400 and 410 electrically to the transparent electrodes 381 and 382 to supply electricity generated by being connected to an external electric circuit. That is, the external terminals 400 and 410 may be formed in a form in which one side is connected to the transparent electrodes 381 and 382 and the other side is electrically connected to the transparent electrode and the side of the substrate by applying a silver paste to the side of the substrate 380. have. Thereafter, the conductive adhesive 510 is coated on the external electrodes 400 and 410, and then the electric wires 520 and 521 are connected to each other so that the dye-sensitized solar cell unit cell 1000 may be provided with electrical connection means for supplying electricity to the outside. .

6 illustrates a module of a dye-sensitized solar cell by serial or parallel connection between unit cells according to an embodiment of the present invention.

As shown in (a) of FIG. 6, the unit cells of the dye-sensitized solar cell are wires 521 connected to the external electrode 410 of the counter electrode unit cell and wires connected to the external electrode 400 of the photoelectrode unit cell. By connecting 520 can be connected in series.

Meanwhile, as shown in (b) of FIG. 6, the unit cells of the dye-sensitized solar cell are connected to the external electrode 400 of the photoelectrode unit cell of the series-connected dye-sensitized solar cell module of FIG. The 520 may be connected in parallel and may be connected in parallel by connecting the wires 521 connected to the external electrode 410 of the counter electrode unit cell to each other.

Therefore, panelization can be achieved on a large area by electrically connecting unit cells of a dye-sensitized solar cell having a predetermined size in series, parallel, series, and parallel.

7 is a plan view of a grid electrode structure of a dye-sensitized solar cell according to another embodiment of the present invention.

As shown in FIG. 7, the second grid electrode 700 corresponding to FIG. 3B has the same width as the grid electrode area of FIG. 3B (because the opening ratio must be the same), and is increasingly wider in the direction of the current collecting electrode 320. It may be formed to have.

Since the electrons collected from the first grid electrode move along the second grid electrode 700 to the current collecting electrode, a portion of the second grid electrode 700 that is far from the current collecting electrode 320 is separated from the first grid electrode. It can be seen that the collected electrons are relatively smaller than the portion in contact with the current collecting electrode 320.

That is, the portion of the second grid electrode 700 that is in contact with the current collecting electrode 320 is important to lower the resistance to smooth the electron transfer to the outside where all the electrons collected from the plurality of grid electrodes gather. The second grid electrode 700 may be formed by forming a portion in contact with the current collecting electrode 320 wider than the other side (W2> W1).

Therefore, in the grid electrode structure according to the present invention, electrons excited from the dye are transparent through a plurality of first grid electrodes formed to intersect with the second grid electrode while maintaining a constant aperture ratio by the same as the total area of the conventional grid electrode. In order to minimize the distance to move on the electrode and to transfer the electrons to the current collecting electrode, the width of the second grid electrode is gradually widened as it moves toward the current collecting electrode at a part far from the current collecting electrode to reduce the resistance. Conversion efficiency can be improved.

The present invention has been described in detail with reference to exemplary embodiments, but those skilled in the art to which the present invention pertains can make various modifications without departing from the scope of the present invention. Will understand.

Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be determined by equivalents to the appended claims, as well as the appended claims.

300: photoelectrode unit cell 320: current collector electrode
330: semiconductor oxide layer 341: first grid electrode
342, 700: second grid electrode 400, 410: external electrode
381,382: transparent electrode 510: conductive adhesive
520,521 Wire 1000: Dye-sensitized solar cell unit cell

Claims

A collecting electrode for connecting the electrons excited from the dye to an external electrical circuit,
At least one first grid electrode formed in a horizontal direction with the current collecting electrode;
The grid electrode structure of the dye-sensitized solar cell comprising a second grid electrode crossing the first grid electrode, one side is formed at least one in the vertical direction to be electrically connected to the current collecting electrode.

The method of claim 1,
The grid electrode structure of the dye-sensitized solar cell, characterized in that the aperture ratio is kept constant by adjusting the widths of the first grid electrode and the second grid electrode.

The method of claim 1,
The grid electrode structure of the dye-sensitized solar cell, characterized in that the width of the second grid electrode is wider than the width of the first grid electrode.

The method of claim 1,
The width of the second grid electrode is a grid electrode structure of the dye-sensitized solar cell, characterized in that gradually widens as it moves toward the current collecting electrode at a portion far from the current collecting electrode.

The method of claim 1,
The current collecting electrode is electrically connected to an external electrode,
The external electrode is a grid electrode structure of a dye-sensitized solar cell, characterized in that formed by applying a silver paste on the side of the substrate.