JP3970358B2 - Solar cell and clock - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention disclosed in this specification relates to a structure of a thin film solar cell. In particular, the present invention relates to the structure of a thin film solar cell disposed on a dial of a watch.
[0002]
[Prior art]
Conventionally, a solar cell using an amorphous silicon (amorphous silicon) film is known.
[0003]
This solar cell using amorphous silicon has high productivity. It can also be thin and light. Solar cells using amorphous silicon make use of this feature and are used as power sources for portable devices such as calculators and watches.
[0004]
This solar cell using amorphous silicon is expected to be used particularly for wristwatches. Quartz-type wristwatches that are widely used generally require a power source. Until now, small mercury batteries and lithium batteries were used. However, when a normal battery is used, its replacement becomes a problem.
[0005]
This battery replacement problem is a major factor that prevents the spread of quartz watches in developing countries and the like.
[0006]
In order to solve such a problem, a configuration in which a solar cell is attached to a wristwatch is known.
[0007]
However, there is a design problem when a solar cell is simply attached to a wristwatch. That is, there is a problem that the appearance as a wristwatch is not good. Another problem is that the size of the solar cell is increased by the amount of space for the solar cell.
[0008]
As a technique for solving such a problem, a structure is known in which the shape of a solar cell is processed into a shape that fits a watch dial and then fitted into the watch dial.
[0009]
As watches having such a structure, those described in pages 71 to 73 of the March 18, 1996 issue of Nikkei Business are on the market.
[0010]
[Problems to be solved by the invention]
When producing a wristwatch incorporating the above-described solar cell, the production cost and reliability are problems.
[0011]
Accordingly, an object of the invention disclosed in this specification is to provide a configuration for producing a solar cell to be incorporated into a wristwatch at low cost. Another object is to obtain it with high reliability.
[0012]
[Means for Solving the Problems]
One of the inventions disclosed in this specification is as shown in FIG.
101 is a solar cell having a circumferential shape shown by 101,
The solar cell is composed of photoelectric conversion elements 104, 105, 106, 107 having a plurality of fan shapes,
In the plurality of photoelectric conversion elements, electrodes (for example, 306 and 305) for connecting in series with other photoelectric conversion elements are arranged in a fan-shaped arc portion,
One of the plurality of photoelectric conversion elements 105 is provided with an output extraction electrode (disposed on the rear surface side of the portion indicated by 601) that is adjacent to the fan-shaped arc portion and penetrates the surface opposite to the light irradiation surface. And
The other one 106 of the plurality of photoelectric conversion elements is disposed on the back side of another output extraction electrode (part indicated by 301) that is adjacent to the fan-shaped arc portion and penetrates the surface opposite to the light irradiation surface. Is provided,
It is characterized by.
[0013]
In the above configuration, the electrode for connecting in series with another photoelectric conversion element and the output extraction electrode penetrating the surface opposite to the light irradiation surface are connected through an open groove formed by laser light irradiation.
[0014]
This is formed by bringing the electrode 202 and the electrode 305 into contact with each other as shown in FIG. This process is known as laser bonding.
[0015]
In the above configuration,
For example, as shown in FIG. 1 and FIG.
A substrate 201;
A first electrode 202 disposed on the substrate;
A photoelectric conversion layer 203 disposed on the first electrode;
A second electrode 206 disposed on the photoelectric conversion layer;
It is configured with
As shown in FIG. 3D, one of the extraction electrodes 308 is in contact with the second electrode 309.
In one of the extraction electrodes 308, the first electrode 202, the photoelectric conversion layer 203, and the second electrode 206 are isolated from each other by the open grooves 208 and 209 reaching the substrate formed by laser scribing. Formed in the region.
[0016]
Other aspects of the invention are:
A solar cell having a polygonal shape,
The solar cell is composed of photoelectric conversion elements having a plurality of polygonal shapes,
In the plurality of photoelectric conversion elements, electrodes for series connection with other photoelectric conversion elements are arranged in a portion adjacent to the outer periphery of the solar cell,
One of the plurality of photoelectric conversion elements is provided with an output extraction electrode penetrating the surface opposite to the light irradiation surface in a portion adjacent to the outer periphery of the solar cell,
Another one of the plurality of photoelectric conversion elements is provided with another output extraction electrode that penetrates the surface opposite to the light irradiation surface in a portion adjacent to the outer periphery of the solar cell,
It is characterized by.
[0017]
In the above configuration,
The electrode for connecting in series with other photoelectric conversion elements and the output extraction electrode penetrating through the surface opposite to the light irradiation surface have a configuration connected through an open groove formed by laser light irradiation. .
[0018]
In the above configuration,
The photoelectric conversion element
A substrate,
A first electrode disposed on a substrate;
A photoelectric conversion layer disposed on the first electrode;
A second electrode disposed on the photoelectric conversion layer;
It is configured with
One of the extraction electrodes is in contact with the second electrode;
One of the extraction electrodes is formed in a region where the first electrode, the photoelectric conversion layer, and the second electrode are isolated and separated from each other by an open groove reaching the substrate formed by laser scribing. It is characterized by.
[0019]
The configuration of another invention is as shown in FIG.
A plurality of photoelectric conversion elements 104, 105, 106, 107 are arranged in a region separated by the open groove 208 having a closed shape,
The plurality of photoelectric conversion elements are separated by a plurality of open grooves 108 and 109 that intersect at the center of the region provided in the region,
The open groove is formed by laser scribing.
[0020]
【Example】
[Example 1]
FIG. 1 shows the appearance of this embodiment. FIG. 1 shows a state in which a solar cell arranged on a dial of a watch is viewed from above. The solar cell shown in FIG. 1 uses a resin film having a thickness of 70 μm and flexibility as a substrate.
[0021]
In FIG. 1, four regions indicated by 104, 105, 106, and 107 are one unit that functions as a photoelectric conversion element. This photoelectric conversion element has a configuration in which a first electrode, a photoelectric conversion layer stacked with NIP, and a second electrode are stacked from the substrate side.
[0022]
These four photoelectric conversion elements are divided into cross characters by linear portions indicated by 108 and 109. This partitioning is performed by cutting using laser light (referred to as laser scribing).
[0023]
Reference numeral 101 denotes an outer peripheral portion of the solar cell. In the final step, this solar cell is punched out as having a circular outer circumference indicated by 101 by laser light irradiation or mechanical means.
[0024]
Reference numeral 208 denotes an outer peripheral portion of the photoelectric conversion element. An annular portion between 208 and 101 is a region that does not function as a solar cell.
[0025]
The outer peripheral portion of the photoelectric conversion element indicated by 208 is also formed by laser scribing as shown in FIGS. 2D and 4D.
[0026]
A dotted line 207 indicates a portion where the second electrode (transparent electrode on the light incident side) of the photoelectric conversion element is selectively cut. This cut portion is also formed by laser scribing as shown in FIG. 2 (C) and FIG. 4 (C).
[0027]
The cut portions 208 and 207 have a circular closed locus. That is, it has a loop shape in which the cutting start point and the end point are connected.
[0028]
2 to 3 show a manufacturing process of a cross section taken along AB in FIG. FIG. 2 to FIG. 3 show a process for producing an external extraction electrode portion (plus-side electrode portion).
[0029]
4 to 5 show a process for producing a cross section taken along CD in FIG. This portion is a connection point between the photoelectric conversion elements 107 and 104.
[0030]
The manufacturing process of each corresponding part is shown below. In this embodiment, a PEN (polyethylene naphthalate) film 201 is used as a substrate.
[0031]
As the substrate, various materials known as industrial plastic materials such as PET (polyethylene terephthalate) can be used.
[0032]
Various processes shown below are continuously performed on the long substrate 201 of several tens to several hundreds of meters until the shape having the appearance shown in FIG. 1 after the final process is obtained. Then, in the final process, it is punched to the appearance shown in FIG.
[0033]
In the above continuous process, various processes such as film formation, printing, various baking, and laser scribing are performed when a long substrate is wound on one roll and wound on the other roll.
[0034]
First, as shown in FIGS. 2A and 4A, an aluminum electrode 202 and a photoelectric conversion layer 203 stacked with NIP from the substrate side are stacked over a substrate 201.
[0035]
The aluminum electrode 202 is formed by sputtering. The photoelectric conversion layer 203 is formed by forming each layer by a plasma CVD method.
[0036]
Next, a first resin layer indicated by 204 and 205 is formed by a printing method. This resin layer is also formed continuously on the long film substrate using a large plate. (See FIG. 2 (A) and FIG. 4 (A))
[0037]
Here, the resin layer 204 is provided in a portion corresponding to the circumference indicated by 208 in FIG. 1 (a cut groove is formed later).
[0038]
In addition, the resin layer 205 is provided in a portion corresponding to the circumference indicated by 207 in FIG. 1 (a cut groove is formed later).
[0039]
Thus, the states shown in FIGS. 2A and 4A are obtained.
[0040]
Next, an ITO electrode 206 is formed by sputtering. The ITO film is also continuously formed on a long film substrate wound up by a roll. In this way, the states shown in FIGS. 2B and 4B are obtained.
[0041]
Next, cutting by laser light irradiation is performed. This process is called a laser scribing process. Here, a necessary layer is cut by irradiating while scanning a YAG laser having a spot diameter of 80 μmφ.
[0042]
Here, the ITO film 206 is cut by laser scribing. In this step, as shown by 207, the ITO film is cut to form an open groove. (See FIGS. 2C and 4C)
[0043]
The cut portion indicated by 207 is formed in a circumferential shape as shown in FIG.
[0044]
When the cutting indicated by 207 is performed by laser light irradiation, it is important that the resin layer 205 exists as a base.
[0045]
If the resin layer 205 is not present, the photoelectric conversion layer 203 may be irradiated with laser light due to variations in the output of the laser light or the like. In an extreme case, an open groove may be formed up to the aluminum electrode 202.
[0046]
It is not a problem that the photoelectric conversion layer 203 is cut below the cut portion 207. (The photoelectric conversion layer outside the circumference 207 does not contribute to photoelectric conversion)
[0047]
However, when the laser beam reaches the aluminum electrode 203, there is a risk that the transparent electrode 206 and the aluminum electrode 202 are short-circuited. In other words, the material constituting the aluminum electrode 202 is melted by the energy of the laser beam and extends to the transparent electrode 206, thereby causing a situation where both electrodes are short-circuited.
[0048]
Further, when the irradiation energy of the laser beam is too strong and the aluminum electrode 202 is completely cut, there is a problem that the photoelectric conversion elements cannot be connected later.
[0049]
That is, when the aluminum electrode 202 is completely cut at the lower portion of the cut portion 207 of the ITO electrode 206 in the cross-section portion shown by CD in FIG. 1 (the cross-section portion shown in FIG. 4), The conversion element cannot be connected to the photoelectric conversion element indicated by 107. (Refer to FIG. 5C))
[0050]
Further, even if the aluminum electrode 202 is not completely cut at the lower portion of the cut portion 207 of the ITO electrode 206, if the portion is damaged by laser light irradiation, contact failure between photoelectric conversion elements and increase in contact resistance may occur. It becomes a factor.
[0051]
In the configuration shown in this embodiment, the presence of the resin layer 205 can prevent the laser beam from reaching the aluminum electrode.
[0052]
Therefore, it is possible to avoid a risk that the transparent electrode 206 and the aluminum electrode 202 are short-circuited. Further, the aluminum electrode 202 can be prevented from being cut or damaged.
[0053]
In this way, the states shown in FIGS. 2C and 4C are obtained. Next, the laser beam output is set higher than that in the case of performing laser scribe indicated by 207, and laser scribe is performed again.
[0054]
In this step, an open groove indicated by 208 and an open groove indicated by 209 are formed. (FIG. 2 (D) and FIG. 4 (D))
[0055]
As is apparent from the figure, in this step, the irradiation condition is set so that the bottom of the groove indicated by 208 or 209 reaches the substrate. Note that the irradiation conditions of the laser light when forming the open grooves indicated by 208 and 209 may be the same.
[0056]
The open groove indicated by 208 is formed as having the same circumferential shape as the open groove indicated by 207.
[0057]
An open groove indicated by 209 is formed to cut the aluminum electrode 202 around the portion where the external lead electrode is provided. The open groove indicated by 209 needs to be formed so that the aluminum electrode 202 is completely cut off from the periphery. That is, it is important that the groove is surely formed inside the groove indicated by 209 so that the aluminum electrode 202 in that portion is isolated from the surroundings.
[0058]
At the time of forming the groove indicated by 208 and 209, the presence of the first resin layers 204 and 205 can prevent the aluminum electrode 202 and the ITO electrode 206 from short-circuiting.
[0059]
If the resin layers 204 and 205 are not present, the distance between the aluminum electrode 202 and the ITO electrode 206 is short, so that both electrodes are often short-circuited by the molten aluminum electrode.
[0060]
In this way, the states shown in FIGS. 2D and 4D are obtained.
[0061]
Next, an open groove 301 shown in FIG. 3A is formed by laser light irradiation. This groove opening is performed under conditions that penetrate to the back surface. The open groove 301 is formed at the position shown in FIG. This open groove 301 is used when forming an extraction electrode finally connected to the back side of the substrate. The portion where the open groove 301 is formed becomes an external extraction electrode portion.
[0062]
Next, as shown in FIGS. 3B and 5A, second resin layers 303 and 304 are formed. These resin layers have a function of filling the open grooves 207 and 208 and further the open grooves 209 with a resin material. Further, it has a function as an interlayer insulating film serving as a base of a contact electrode formed thereon.
[0063]
The formation of the second resin layers 303 and 304 is also performed by a printing method.
[0064]
Next, as shown in FIG. 3C and FIG. 5B, contact electrodes 305, 306, and 307 made of silver paste are formed. This contact electrode is also formed by a printing method. The positional relationship between the contact electrodes is shown in FIG.
[0065]
In the state shown in FIG. 5B, laser light irradiation is performed on the portion indicated by the arrow in the drawing to form a contact between the aluminum electrode 202 and the contact electrode 305. In this step, a contact for electrically connecting both the silver paste and the aluminum electrode is formed by simultaneously melting the silver paste and the aluminum electrode at the same time as forming the contact groove. Such a process is known as laser bonding.
[0066]
Thus, as shown in FIG. 5C, the cross section indicated by CD in FIG. 1 is completed. This portion has a state in which the aluminum electrode 202 of the photoelectric conversion element 107 is connected to the silver paste pattern 305 connected to the ITO electrode of the photoelectric conversion element 104 by laser bonding.
[0067]
Thus, a state in which the photoelectric conversion element 104 and the photoelectric conversion element 107 are connected in series is obtained. There are three other connection points. With this connection structure, the photoelectric conversion elements 105, 104, 107, and 106 are connected in series in order.
[0068]
On the other hand, on the cut surface indicated by A-B (see FIG. 3), after the contact electrode 307 made of silver paste is formed, the contact electrode 308 is formed on the back surface side with silver paste. The contact electrode 308 is also formed by a printing method. (See FIG. 3C and FIG. 3D)
[0069]
The contact electrode 308 contacts the contact electrode 307 in the open groove 301. Then, a structure is formed in contact with the ITO electrode 309 of the photoelectric conversion element 106.
[0070]
That is, the contact electrode 308 formed on the surface opposite to the side shown in FIG. 1 serves as an extraction electrode from the ITO electrode 309 (see FIG. 3) of the photoelectric conversion element 106 (see FIG. 1).
[0071]
The ITO electrode 309 is in contact with the P-type semiconductor layer on the light incident side of the photoelectric conversion element 106. Accordingly, the contact electrode 308 serves as an extraction electrode that outputs a positive potential.
[0072]
FIG. 6 shows a cross-sectional structure indicated by EF and GD in FIG. Here, an extraction electrode (being a negative potential side electrode) from the N-type semiconductor layer of the photoelectric conversion element 105 is formed.
[0073]
A cross section indicated by E-F is shown in FIG. A cross section indicated by GD is shown in FIG. As shown in FIG. 6A, an electrode 602 made of silver paste in contact with the aluminum electrode 202 (the aluminum electrode of the photoelectric conversion element 107) is formed on the back side of the substrate 201.
[0074]
In order to ensure contact between the aluminum electrode 202 and the extraction electrode 602, a cross section indicated by GD has a structure as shown in FIG.
[0075]
That is, a contact indicated by 603 is formed at a portion indicated by 604 by using laser bonding. That is, in the portion indicated by 603, the aluminum electrode 202 and the electrode 601 made of silver paste are in contact with each other.
[0076]
Finally, a large number of solar cells formed using a long film as a substrate are mechanically punched to complete individual solar cells. That is, a large number of solar cells whose appearance is shown in FIG.
[0077]
In this way, the solar cell whose appearance from the upper surface is shown in FIG. 1 is the extraction electrode 308 (see FIG. 3) from the P-type semiconductor layer of the photoelectric conversion element 106 (present on the back surface of the open groove 301). And a configuration in which the photovoltaic power is extracted from the extraction electrode 602 (see FIG. 6) from the N-type semiconductor layer of the photoelectric conversion element 105 (present on the back side of the electrode 601).
[0078]
In this embodiment, an example is shown in which the overall shape is circular and each photoelectric conversion element has a fan shape. However, the overall shape may have a polygonal shape such as a quadrangle, a hexagon, or an octagon.
[0079]
[Example 2]
This embodiment shows a laser scribing method in the configuration shown in Embodiment 1. As a method of laser scribing, a method of forming an open groove in a predetermined pattern by scanning and irradiating spot-like laser light is employed.
[0080]
Here, the following problems occur when the circumferential grooves shown by 208 and 207 in FIG. 1 are formed.
[0081]
FIG. 7A shows a trajectory when laser light is irradiated from the start point indicated by 701, travels around the circumference, returns to the start point 701, and laser scribing is completed.
[0082]
The spot diameter of the laser scribe is about several tens μm to several hundreds μm. On the other hand, in a continuous process using a long film as shown in Example 1 as a substrate, it is difficult to suppress the positional deviation of the spot diameter.
[0083]
Therefore, when a large number of steps are continuously performed, a situation occurs in which the start point and end point of laser scribing do not completely coincide.
[0084]
In addition, a vertical short circuit occurs between the point where laser light irradiation is performed first (laser scribing start point) and the last point where laser light irradiation is performed (laser scribing end point) across the photoelectric conversion layer. There is a problem that it is easy.
[0085]
In order to solve these problems, the structure shown in this embodiment is characterized in that laser scribing is performed along a locus as shown in FIG. That is, as indicated by reference numeral 702, the scribing start point (start position) 703 and the end point (end position) 704 do not exist in the region 705 where the photoelectric conversion element is formed (inside the scribed trajectory).
[0086]
That is, a scribing start point (start position) 703 and an end point (end position) 704 exist outside the arc of the photoelectric conversion element.
[0087]
By doing so, the scribe locus can be reliably closed. Further, it is possible to eliminate the influence due to the existence of the scribe start point and end point. That is, since the scribing start point 703 and the end point 702 do not exist in the element region 705, there can be no problem even if a short circuit occurs between these points.
[0088]
【The invention's effect】
By utilizing the invention disclosed in this specification, a structure for producing a solar cell to be incorporated into a wristwatch at low cost can be provided. It can also be obtained with high reliability.
[0089]
Further, since the electrode portion for taking out the output can be provided on the opposite side of the light irradiation surface, the configuration of the output taking-out portion can be simplified. In addition, the area contributing to photoelectric conversion can be maximized.
[Brief description of the drawings]
FIG. 1 is a diagram showing the appearance of a solar cell.
2A and 2B are cross-sectional views illustrating a manufacturing process of a portion indicated by AB in FIG. 1;
3A and 3B are cross-sectional views illustrating a manufacturing process of a portion indicated by AB in FIG. 1;
4 is a cross-sectional view showing a manufacturing step of a portion indicated by CD in FIG. 1;
5A and 5B are cross-sectional views illustrating a manufacturing process of a portion indicated by CD in FIG. 1;
6 is a view showing a cross section indicated by EF and GD in FIG. 1. FIG.
FIG. 7 is a view showing a locus of laser scribe.
[Explanation of symbols]
101 Photoelectric conversion element 105 Photoelectric conversion element 106 Photoelectric conversion element 107 Photoelectric conversion element 108 Laser scribe part 109 Laser scribe part 201 Resin substrate 202 Aluminum electrode (first electrode)
203 Photoelectric conversion layer (NIP type semiconductor layer)
204 Resin layer (first resin layer)
205 Resin layer (first resin layer)
206 ITO electrode 207 Groove by laser scribe 208 Groove by laser scribe 209 Groove by laser scribe 301 Groove by laser scribe 303 Resin layer (second resin layer)
304 resin layer (second resin layer)
305 Contact electrode 306 by silver paste Contact electrode 307 by silver paste Contact electrode 308 by silver paste Contact electrode 309 by silver paste ITO electrode 601 Contact electrode 602 by silver paste Contact electrode 603 by silver paste Contact part by laser bonding

Claims (9)

A solar cell comprising: a first electrode disposed on a substrate; a semiconductor layer disposed on the first electrode; and a second electrode disposed on the semiconductor layer,
The solar cell has a first circumferential shape;
Inside the first circumferential shape, an opening groove for cutting the second electrode into a second circumferential shape and a plurality of opening grooves intersecting at the center of the second circumferential shape, A plurality of photoelectric conversion elements having a fan shape in which the first electrode, the semiconductor layer, and the second electrode are stacked in this order are formed,
In the plurality of photoelectric conversion elements, a plurality of third electrodes that are in contact with the second electrode are arranged in a fan-shaped arc portion,
In a region between the first circumferential shape and the second circumferential shape, the third electrode is connected to the first electrode, whereby the plurality of photoelectric conversion elements are connected in series. A solar cell characterized by being made. In claim 1,
In the region between the first circumferential shape and the second circumferential shape, a region is formed in which the first electrode, the semiconductor layer, and the second electrode are isolated from each other. And
In the isolated region, an output extraction electrode provided on the back surface of the substrate and one of the plurality of third electrodes are connected via an open groove penetrating the back surface of the substrate. Solar cell featuring. A first electrode disposed on a substrate; a semiconductor layer disposed on the first electrode; a resin layer selectively disposed on the semiconductor layer; the semiconductor layer and the resin layer A second electrode disposed on the solar cell,
The solar cell has a first circumferential shape;
The inside of the first circumferential shape intersects with a first open groove for cutting the second electrode on the resin layer into a second circumferential shape at the center of the second circumferential shape. A plurality of photoelectric conversion elements having a sector shape in which the first electrode, the semiconductor layer, and the second electrode are stacked in this order are formed by a plurality of second open grooves,
In the plurality of photoelectric conversion elements, a plurality of third electrodes that are in contact with the second electrode are arranged in a fan-shaped arc portion,
In a region between the first circumferential shape and the second circumferential shape, the third electrode is connected to the first electrode, whereby the plurality of photoelectric conversion elements are connected in series. Has been
In a region between the first circumferential shape and the second circumferential shape, the first electrode, the semiconductor layer, the resin layer, and the second electrode are formed in a laminated portion. A region where the first electrode, the semiconductor layer, and the second electrode are isolated from each other is formed by the third groove.
In the isolated region, an output extraction electrode provided on the back surface of the substrate and one of the plurality of third electrodes are connected via a fourth open groove penetrating the back surface of the substrate. A solar cell characterized by being. In claim 3,
The third open groove is formed by irradiating a laser beam. In claim 3 or claim 4,
An open groove having a third circumferential shape reaching the substrate surface is formed in a region between the first circumferential shape and the second circumferential shape, and the third circumferential shape Only the semiconductor layer in the inner region of the glass contributes to photoelectric conversion,
The groove having the third circumferential shape is formed by irradiating a laser beam to a portion where the first electrode, the semiconductor layer, the resin layer, and the second electrode are stacked. A solar cell characterized by. In any one of Claims 1 thru | or 3,
An open groove having a third circumferential shape reaching the substrate surface is formed in a region between the first circumferential shape and the second circumferential shape, and the third circumferential shape Only the semiconductor layer in the inner region of the solar cell contributes to photoelectric conversion. In any one of Claims 1 thru | or 6,
The solar cell according to claim 2, wherein the locus of the second circumferential shape intersects at one place. In any one of Claims 1 thru | or 6,
2. The solar cell according to claim 1, wherein the locus of the second circumferential shape intersects at one place, and the start point and the end point of the locus exist outside the arc. A timepiece comprising the solar cell according to any one of claims 1 to 8 arranged on a dial.

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