JP2002076406A - Thin film solar battery and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin film solar battery having excellent characteristic by preventing damage to a thin film which is generated at laser patterning, and a method for manufacturing the thin film solar battery. SOLUTION: In a thin film solar battery using a substrate wherein a laser beam is transmitted, material of a first electrode layer L and a third electrode layer b is single metal of silver or aluminum, alloy, etc., and has reflectance higher than that of a fourth electrode layer e. Material of the fourth electrode layer e is nickel, ITO(indium tin oxide), copper, etc., and has reflectance lower than that of the third electrode layer b. The thickness of the first electrode layer L is made equivalent to or greater than that of the third electrode layer b. In a thin film solar battery using a substrate wherein a laser beam is absorbed by adding coloring agent, a photoelectric conversion part having a photoelectric conversion layer (a) is formed on the surface on the side wherein density of coloring agent in the substrate is low.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a thin-film solar cell and a method for manufacturing the same.

[0002]

2. Description of the Related Art At present, research and development of clean energy are being promoted from the standpoint of environmental protection. Above all, solar cells are attracting attention because of their infinite resources (solar rays) and no pollution. A typical example of a solar cell (photoelectric conversion device) in which a plurality of solar cell elements formed on the same substrate are connected in series is a thin-film solar cell.

Thin-film solar cells are considered to be the mainstream of solar cells in the future because of their thinness, light weight, low production cost, and easy area enlargement. Demand is expanding for business use and general residential use, which are used for such purposes.

Conventional thin-film solar cells use a glass substrate, but research and development of a flexible solar cell using a plastic film has been advanced in terms of weight reduction, workability, and mass productivity. Further, a device using a film substrate insulated from a flexible metal material has been developed. Taking advantage of this flexibility, mass production has become possible by roll-to-roll or stepping roll manufacturing methods.

In the above-mentioned thin film solar cell, a first electrode (hereinafter, also referred to as a lower electrode), a photoelectric conversion layer comprising a thin film semiconductor layer, and a second electrode (hereinafter, also referred to as a transparent electrode) are formed on a flexible electrically insulating film substrate. ) Are formed in a plurality of photoelectric conversion elements (or cells). By repeatedly electrically connecting the first electrode of a certain photoelectric conversion element and the second electrode of the adjacent photoelectric conversion element, the first electrode of the first photoelectric conversion element and the second electrode of the last photoelectric conversion element Required voltage can be output. For example,
Alternating with an inverter, AC 100 as commercial power source
In order to obtain V, the output voltage of the thin-film solar cell must be 100 V
The above is desirable, and actually several tens or more elements are connected in series.

[0006] Such a photoelectric conversion element and its serial connection are formed by forming an electrode layer and a photoelectric conversion layer, patterning each layer, and combining them. An example of the configuration and the manufacturing method of the solar cell is disclosed in, for example,
No. 0-233517 and Japanese Patent Application No. 11-19306.

FIG. 4 shows an example of a thin-film solar cell described in the above-mentioned Japanese Patent Application Laid-Open No. Hei 10-233517. FIG. 4A is a plan view, and FIG. 4B is a line ABCD and BQ in FIG.
It is sectional drawing along C, (c) is E in (a).
E shows a sectional view.

A first electrode layer, a photoelectric conversion layer, and a second electrode layer are sequentially laminated on a long film substrate made of an electrically insulating and flexible resin. The three electrode layer and the fourth electrode layer are stacked to form a back electrode. The photoelectric conversion layer is, for example, a pin junction of amorphous silicon. As the material for the film substrate, a polyimide film, for example, a film having a thickness of 50 μm is used.

Other materials for the film include polyethylene naphthalate (PEN) and polyether sulfone (P
ES), polyethylene terephthalate (PET), or aramid-based films can be used.

Next, an outline of the manufacturing process will be described below.

First, a connection hole h1 is formed in a film substrate by using a punch, and silver is formed as a first electrode layer on one side (front side) of the substrate by sputtering, for example, to a thickness of 100 nm. On the opposite side (the back side)
Similarly, a silver electrode is formed as an electrode layer. The first electrode layer and the third electrode layer overlap with each other on the inner wall of the connection hole h1 and conduct.

The electrode layer is made of not only silver (Ag) but also Al, C
A metal such as u or Ti may be formed by sputtering or electron beam evaporation, or a multilayer film of a metal oxide film and a metal may be used as the electrode layer.

After the film formation, on the front side, the first electrode layer is laser-processed into a predetermined shape, and the lower electrodes 11 to 16 are patterned. A portion adjacent to the lower electrodes 11 to 16 is a single separation line g2.
For separation between two rows of photoelectric conversion elements connected in series and the periphery conductive portion f, two separation lines g2 are formed, and the lower electrodes 11 to 16 are surrounded by the separation lines. After the current collecting hole h2 is opened again by using a punch, an a-Si layer is formed as a photoelectric conversion layer p on the front side by plasma CVD. A film having a width W2 is formed using a mask, and the same separation line as that of the first electrode layer is formed only between the two-row elements by laser processing.

Further, a transparent electrode layer (ITO layer) is formed on the front side as a second electrode layer. However, a mask is applied between the two element rows and on both side edges of the substrate parallel to the two element rows to form connection holes h1.
Is formed only on the element portion. As the transparent electrode layer, besides ITO (Indium Sulfate), SnO
2. An oxide conductive layer such as ZnO can be used.

Next, a silver electrode is formed as a fourth electrode layer on the entire back surface. Due to the formation of the fourth electrode, the second electrode and the fourth electrode are overlapped on the inner wall of the current collecting hole h2, and conduction is achieved. On the front side, a separation line having the same pattern as that of the lower electrode is formed by laser processing to form individual second electrodes u1 to u6. On the rear side, the third electrode and the fourth electrode are simultaneously laser-processed, and the connection electrode e
12 to e56 and the power extraction electrodes o1 and o2 are individualized, a separation line g2 is formed at the periphery of the substrate so as to overlap the separation line g3 on the front side, and one separation line is formed between adjacent electrodes.

In order to process the connection electrode on the back surface with a low-output laser, the material of the fourth electrode is often made of a material having a relatively low reflectance. Ni, ITO, Cu, or the like is used as a material having a low reflectance.

There is a separation line g3 (inside the peripheral conductive portion f) at the periphery surrounding all the thin-film solar cells collectively and at the adjacent boundary between the two rows of series-connected solar cells. There are no layers in the separation line g3. On the rear side, there is a separation line g2 (inside the peripheral conductive portion f) at the periphery surrounding all the electrodes collectively and at the adjacent boundary between the two rows of serially connected electrodes. There are no layers in the separation line g2.

In this manner, the power extraction electrode o1-current collection hole h2-upper electrode u1, photoelectric conversion layer, lower electrode l1-connection hole h
1-connection electrode e12-upper electrode u2, photoelectric conversion layer, lower electrode 12-connection electrode e23-...-upper electrode u6, photoelectric conversion layer, lower electrode 16-connection hole h1-photoelectric extraction electrode o2 in the order of: The serial connection of the conversion elements is completed.

Since the third electrode layer and the fourth electrode layer have the same electric potential, they may be treated as a single connection electrode layer in the following description for convenience of explanation.

FIG. 5 is a simplified perspective view of the structure of a thin-film solar cell for easy understanding of the structure. In FIG. 5, the unit photoelectric conversion element 62 formed on the front surface of the substrate 61 and the connection electrode layer 63 formed on the back surface of the substrate 61 are completely separated into a plurality of unit units, respectively, and are formed with their separation positions shifted. ing. Therefore, the current generated in the photoelectric conversion layer 65, which is the amorphous semiconductor portion of the element 62, is first collected in the transparent electrode layer 66, and then the current collecting holes 67 formed in the transparent electrode layer region.
(H2) through the connection electrode layer 63 on the back surface, and further through the connection electrode 68 (h1) for series connection formed outside the transparent electrode layer region of the device in the connection electrode layer region, and connected to the device. Reaching the lower electrode layer 64 extending outside the transparent electrode layer region of the adjacent element, the two elements are connected in series.

FIGS. 6A to 6G show a simplified manufacturing process of the above-mentioned thin film solar cell. Plastic film 71
Is used as a substrate (step (a)), connection holes 78 are formed in the substrate (step (b)), and a first electrode layer (lower electrode) is formed on both surfaces of the substrate.
After forming the first electrode layer 74 and the third electrode layer (part of the connection electrode) 73 (step (c)), a current collecting hole 77 is formed at a position separated from the connection hole 78 by a predetermined distance (step (d)). Next, a semiconductor layer 75 serving as a photoelectric conversion layer and a transparent electrode layer 76 serving as a second electrode layer are sequentially formed on the first electrode layer 74 (step (e) and step (f)). Electrode layer 73
A fourth electrode layer (connection electrode layer) 79 is formed on the substrate (step (g)). Thereafter, the thin films on both sides of the substrate 71 are separated and processed by using a laser beam to form a series connection structure as shown in FIG.

In FIG. 6, the connection between the transparent electrode layer 76 and the fourth electrode layer 79 in the current collecting hole h2 is shown by two layers with each layer being superposed. In FIG. 5, it is treated as one layer electrically, and is shown in one layer.

In the manufacturing process of the thin-film solar cell, the step (b) of forming the connection hole 78 and the step (d) of forming the current collecting hole 77 are performed by punching using a punch (Japanese Patent Laid-Open No. 8-139352). Gazette). Regarding the punching process using a punch, the applicant of the present application has proposed a continuous hole forming apparatus with high productivity.
No. 2). This continuous hole processing apparatus includes a substrate transporting means, a through hole processing means, and a processing position detection hole processing means, and the substrates sent out from the unwinding roll sequentially receive a hole opening for processing position detection, a collecting hole. After a predetermined number of processing position detection holes, current collection holes and connection holes are opened at predetermined positions by the electrode hole opening portion and the connection hole opening portion, and after being cleaned by the cleaning device,
It is taken up by a take-up roll. The transport direction and transport distance of the substrate are controlled based on the holes for processing position detection in correspondence with various hole positions.

FIG. 7 is a plan view showing an example of the arrangement of the position detecting holes h3, the connection holes h1, and the current collecting holes h2 on the substrate.
The position detection holes h3 provided in the substrate 1a are opened at predetermined intervals of a predetermined unit pattern of the solar cell, and are used for positioning the transfer of the substrate.

In the above description, an example in which a resin film is used as a substrate has been mainly described. However, a thin-film solar cell having heat resistance capable of forming a semiconductor layer at 400 ° C. or higher and a method of manufacturing the same are provided. For this purpose, a device using a conductive base material such as a metal has been proposed (Japanese Patent Application No. Hei 11 (1999) -207).
-133647).

In the above-described thin-film solar cell, a connection hole is formed in a conductive base material, and an electric insulating layer of a heat-resistant polymer resin is formed on a main surface of the base material and an inner peripheral surface of the connection hole. And forming the first electrode layer of the thin-film solar cell on the inner peripheral surface of the connection hole, and forming the third electrode layer on the back surface of the substrate and the inner peripheral surface of the connection hole. The third electrode layer is electrically connected. Thereafter, a current collecting hole is formed, and a photoelectric conversion layer and a transparent electrode layer are sequentially formed on the surface of the substrate on which the first electrode layer is formed and on the inner peripheral surface of the current collecting hole. Thereafter, a fourth connection electrode is formed on the back surface side of the substrate on which the third electrode layer is formed and on the inner peripheral surface of the current collection hole on which the transparent electrode layer is formed. Although the four connection electrode layers are electrically connected, the basic part of the manufacturing method is the same as the above-described method.

[0027]

By the way, the above-mentioned conventional thin-film solar cell and its manufacturing method have the following problems.

In a thin-film solar cell using a substrate that transmits laser light, at the time of patterning the connection electrode layer, the laser light transmitted through the substrate has a thermal effect on the photoelectric conversion portion on the surface opposite to the connection electrode layer. There have been problems such as peeling and short-circuiting of the thin-film solar cell.

In order to solve the above problem, a substrate may be used in which a colorant is added to the substrate to reduce the transmittance of the laser beam and absorb the laser beam. During the patterning of the electrode layer, the colorant of the substrate material that has absorbed the laser beam evaporates, causing a problem of damaging the photoelectric conversion portion on the side opposite to the connection electrode layer.

Further, in order to improve the adhesive force between the substrate and the first or third electrode layer, a substrate having a contact area increased by making both surfaces of the front surface and the rear surface uneven is sometimes used. In this case, too, a problem often occurs that the photoelectric conversion unit is damaged.

Further, in order to prevent short circuit due to migration and to enhance the reliability of the thin-film solar cell, the width of the processing line of the connection electrode layer, that is, the width of the patterning separation groove is increased. In this case, it is necessary to overlap a plurality of laser processing lines. However, when the laser processing lines are overlapped, there is a problem that the photoelectric conversion portion in the overlapping portion is damaged.

The present invention has been made to solve the above problems, and an object of the present invention is to prevent a thin film from being damaged during laser patterning and to have good solar cell characteristics. An object of the present invention is to provide a thin-film solar cell and a method for manufacturing the same.

[0033]

In order to solve the above-mentioned problems, according to the present invention, a first electrode layer as a lower electrode layer, a photoelectric conversion layer, and a transparent electrode are provided on a surface of a film substrate made of a translucent resin material. A photoelectric conversion unit formed by sequentially stacking layers (second electrode layers); and a third electrode layer and a fourth electrode layer serving as connection electrode layers formed on the back surface of the substrate. The layers are displaced from each other and patterned into unit portions by a laser processing method, connection holes for electrical series connection formed outside the transparent electrode layer formation region, and current collection formed in the transparent electrode layer formation region In a thin-film solar cell in which unit photoelectric conversion portions that are patterned and mutually adjacent on the surface and that are adjacent to each other through a hole are electrically connected in series, the material of the first electrode layer and the third electrode layer is silver or Al A material having a higher reflectivity than at least the fourth electrode layer, such as a single metal or alloy of nickel, and a material of the fourth electrode layer is at least the third material such as nickel, ITO (indium tin oxide), copper or the like. A material having a lower reflectivity than the electrode layer;
The thickness of the electrode layer is equal to or greater than the thickness of the third electrode layer (the invention of claim 1). In the thin-film solar cell according to the first aspect, the film substrate made of the translucent resin material has a light transmittance of 60% or more with respect to the laser wavelength (the invention of the second aspect).

According to the first aspect of the present invention, the fourth electrode layer is made of a material having a low reflectance to improve the efficiency of inputting laser light, and the thickness of the first electrode layer is made smaller than that of the third electrode layer. By increasing the thickness, the laser output required for processing the connection electrode layer can be made lower than that of the first electrode layer, and the first electrode layer is not processed by the laser during the laser processing of the connection electrode layer. be able to. Thereby, the influence of heat on the photoelectric conversion unit can be suppressed, and the problems of film peeling and short-circuiting of the thin-film solar cell occur. This is particularly effective in the second aspect of the invention.

Further, in a thin-film solar cell using a substrate in which a coloring agent is added to the substrate, the following invention of claim 3 is preferable. That is, a first electrode layer as a lower electrode layer, a photoelectric conversion layer, and a transparent electrode layer (second electrode layer) are formed on a surface of a film substrate obtained by adding a coloring agent to a resin material in order to prevent transmission of laser light used for patterning. And a third electrode layer and a fourth electrode layer as connection electrode layers formed on the back surface of the substrate, wherein the photoelectric conversion unit and the connection electrode layer are displaced from each other. The unit portion is patterned by a laser processing method, and the surface is formed through a connection hole for electrical series connection formed outside the transparent electrode layer forming region and a current collecting hole formed in the transparent electrode layer forming region. In the thin-film solar cell in which the adjacent unit photoelectric conversion portions are electrically connected in series to each other on the upper side, the photoelectric conversion portion is formed on a surface of the substrate on which the colorant concentration is low.

The reason why the invention of claim 3 is effective is as follows.
According to the following. When a colorant is added to a substrate resin, it is difficult to uniformly add the colorant in the thickness direction of the resin, and a concentration difference of the colorant occurs in the thickness direction of the substrate. As described above, the damage to the photoelectric conversion unit is caused by the evaporation of the colorant of the substrate material that has absorbed the laser light,
When the first electrode layer is formed on a surface where the concentration of the coloring agent is high, the first electrode layer formed on the substrate is relatively easily blown off by the vapor of the coloring agent. Therefore, by forming the photoelectric conversion portion including the first electrode layer on the surface of the substrate where the concentration of the coloring agent is lower than that of both surfaces of the substrate, the problem of causing damage can be suppressed.

Further, in a thin-film solar cell using a substrate which has been subjected to the above-mentioned roughening treatment, the following invention of claim 4 is preferable. That is, a photoelectric conversion unit in which a first electrode layer as a lower electrode layer, a photoelectric conversion layer, and a transparent electrode layer (second electrode layer) are sequentially laminated on a surface of a film substrate made of a resin material, Third connection electrode layer formed
An electrode layer and a fourth electrode layer, wherein the photoelectric conversion unit and the connection electrode layer are formed by patterning a unit portion by a laser processing method while displacing the positions from each other, and an electrical series formed outside the transparent electrode layer formation region. A thin-film solar cell in which unit photoelectric conversion portions that are patterned and mutually adjacent on the surface are electrically connected in series via a connection hole for connection and a current collection hole formed in the transparent electrode layer formation region. In the above-mentioned substrate, in order to improve the adhesion between the substrate and the first electrode layer or the third electrode layer, both surfaces of the front and back surfaces thereof are made uneven to increase the contact area, and The photoelectric conversion unit is formed on the surface of the front surface or the back surface on the side where the formed unevenness is large and the contact area is large.

The above roughening treatment is performed by high frequency plasma etching. The degree of roughening is different between the front surface and the back surface of the substrate. It is considered that the formed surface having small unevenness and small contact area is likely to cause film peeling because the adhesive force between the substrate and the thin film electrode layer is weak, and therefore, the structure of the invention of claim 4 is adopted. Thus, it is considered that the problem of causing damage can be suppressed.

Furthermore, as described above, the method of manufacturing a thin-film solar cell in which the width of the patterning separation groove is widened is preferably the following invention. That is, a photoelectric layer formed by sequentially laminating a first electrode layer as a lower electrode layer, a photoelectric conversion layer, and a transparent electrode layer (second electrode layer) on the surface of a film substrate made of a resin material or a metal material covered with an electric insulation. A conversion part, and a third electrode serving as a connection electrode layer formed on the back surface of the substrate.
An electrode layer and a fourth electrode layer, wherein the photoelectric conversion unit and the connection electrode layer are formed by patterning a unit portion by a laser processing method while displacing the positions from each other, and an electrical series formed outside the transparent electrode layer formation region. A thin-film solar cell in which unit photoelectric conversion portions that are patterned and mutually adjacent on the surface are electrically connected in series via a connection hole for connection and a current collection hole formed in the transparent electrode layer formation region. In the manufacturing method, the patterning is a patterning method in which a plurality of laser processing lines are overlapped to form a patterning separation groove, and an overlap width dimension of a laser pulse in the laser processing line is equal to or less than half of a spot diameter dimension of the laser pulse. And

According to the fifth aspect of the present invention, as will be described later in detail, the number of laser pulse irradiations can be limited to four or less, and damage to the photoelectric conversion unit can be eliminated.

[0041]

Embodiments of the present invention will be described below with reference to the drawings.

Example 1 Table 1 shows a sample obtained by using a heat-resistant polymer aramid resin having a thickness of 25 μm for a substrate, and forming silver thereon as a first electrode layer by sputtering at a film forming temperature of 300 ° C. It shows the relationship between laser processing output and damage to the first electrode layer when the second harmonic of a YAG laser is made from the substrate side. At this time, the transmittance of the substrate with respect to the laser wavelength is 60%, and the thickness of the first electrode layer is 0.1 to
0.3 μm.

[0043]

[Table 1]

From Table 1, it can be seen that the laser processing output at which the damage to the first electrode layer occurs increases as the thickness of the first electrode increases. As described later, the third electrode layer (silver 0.2 μm)
m) and the fourth electrode layer (Ni 300-500 nm) to process and remove the connection electrode layer requires 0.8 mJ / pulse or more. In this case, the thickness of the first electrode layer must be 0.2 μm or more. Is desirable.

FIG. 1 is a diagram showing a manufacturing process of a thin-film solar cell manufactured based on the above results. Hereinafter, a method for manufacturing a thin-film solar cell according to the first aspect of the present invention will be described with reference to FIG.

First, a connection hole h1 was formed in a 38 μm-thick aramid substrate 10 using a punch. A first electrode layer L made of a highly reflective metal such as silver is formed thereon with a thickness of 0.2 μm, and a third electrode layer b of the same material as the first electrode layer is formed on the opposite main surface with a thickness of 0.2 μm.
It was formed by a sputtering method with a film thickness of μm. The electrode forming temperature at this time was 300 ° C. As a result of this step, the first electrode layer L and the third electrode layer b were electrically connected via the series connection hole h1.

The first electrode layer L was patterned using the second harmonic of the YAG laser, and divided into a plurality of units.

Thereafter, a current collecting hole h2 is formed using a punch, and a photoelectric conversion layer a made of an a-Si layer is formed on the first electrode layer.
By plasma CVD, a fourth electrode layer e made of nickel having a low light reflectance was sequentially formed on the transparent electrode layer u on the light incident side and the main surface on the opposite side by using a sputtering method.
As a result of this step, the transparent electrode layer u and the fourth
The electrode layer e was electrically connected. The thickness of the fourth electrode layer e is
300-500 nm.

Finally, a connection electrode layer consisting of the transparent electrode layer u and the photoelectric conversion layer a in the first electrode layer patterning line, and the third electrode layer b and the fourth electrode layer e on the opposite side are formed.
Patterning was performed using the second harmonic of a YAG laser to form a thin-film solar cell in which a plurality of thin-film solar cell elements were connected in series.

According to this embodiment, the thickness of the first electrode layer is set to 0.
By setting the thickness to 2 μm, it was possible to eliminate the damage of the photoelectric conversion portion at the time of processing the connection electrode layer.

Example 2 Table 2 shows that a substrate was used in which a coloring agent was added to a heat-resistant polymer polyimide resin having a thickness of 50 μm, and silver was formed thereon as a first electrode layer at a film forming temperature of 300 ° C.
This is a graph showing the relationship between laser processing output and damage to the first electrode layer when a second harmonic of a YAG laser is incident from the substrate side after preparing a sample formed by sputtering 0.2 μm.
At this time, the transmittance of the substrate with respect to the laser wavelength is 20% or less, and most of the laser light is absorbed by the substrate.

[0052]

[Table 2]

From Table 2, it can be seen that the laser processing output at which the first electrode layer damage occurs differs between the front and back of the substrate.
This is because it is difficult to uniformly add the colorant to the resin in the thickness direction, and when the first electrode layer is formed on the surface where the concentration of the colorant is high, the colorant evaporates by laser light irradiation, and the vapor is generated by the vapor. It is considered that the first electrode layer formed on the substrate blows away.

Based on the above results, the plate thickness to which the coloring agent was added
Using a 38 μm polyimide substrate, a thin-film solar cell was manufactured in the same procedure as in FIG. However, in this case, it is not necessary to make the thickness of the first electrode layer equal to or more than the thickness of the third electrode layer as in the first embodiment.

As a result, it was possible to eliminate damage to the photoelectric conversion portion during processing of the connection electrode layer.

In this embodiment, the use of the front and back sides of the substrate relating to the difference in the concentration of the colorant in the thickness direction of the substrate has been described.
Similarly, the same effect as that of the present embodiment can be obtained by forming the photoelectric conversion portion on the surface which is hard to receive damage by properly using the front and back surfaces of the substrate in relation to the degree of the surface unevenness treatment on the front and back surfaces of the substrate.

(Embodiment 3) FIG. 2 is a plan view of a thin-film solar cell according to the fifth aspect of the present invention, and FIG. 3 schematically shows a superimposed image of a connection electrode layer laser processing line.

FIG. 2 is a plan view of a thin-film solar cell in which three thin-film solar cells in seven series are formed in parallel on a heat-resistant polymer substrate. FIG. 2A shows a surface on which a photoelectric conversion unit is formed,
FIG. 2B shows the back surface on which the connection electrode layer is formed. 2, the same members or the same functional portions as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 2A, in this thin-film solar cell, the photoelectric conversion layer a formed on the first electrode layer is divided into three regions by a separation portion s. The layer u is formed on the photoelectric conversion layer a in three regions. These three transparent electrode formation regions are power generation regions. On the back surface, as shown in FIG. 2B, the connection electrode layer e is divided into three regions by the separation portion s, and the extraction electrodes t are connected to the connection electrode layers at both ends. In FIG. 2, the separation part s has a wide patterning separation groove, and adopts a patterning method of forming a patterning separation groove by overlapping a plurality of laser processing lines.

In this embodiment, as shown in FIG. 3, in order to prevent short-circuiting of the connection electrode due to migration or the like, the width of the connection electrode is set to 0.
0.4μm width by superposing 3 2μm laser processing lines
Of the connection electrode layer. At this time, the overlap width of the laser pulses constituting the laser processing line is 0.1 μm, which is half of the laser spot diameter, and is the same as the overlap width of the laser processing line.

As described above, when the overlap width of the laser pulse and the overlap width of the laser processing line are not more than half of the laser spot diameter, the laser pulse irradiated to the connection electrode layer laser processing portion can be reduced to 4 pulses or less. it can.

Next, the manufacturing process of the thin-film solar cell of this embodiment will be described. In this embodiment, a connection hole h1 was formed in the aramid substrate 1 by using a punch by using an aramid resin having a thickness of 20 μm for the substrate. A first electrode layer made of a highly reflective metal such as silver was formed thereon by a thickness of 0.2 μm, and a third electrode layer having a thickness of 0.2 μm was formed on the opposite main surface by a sputtering method. The electrode forming temperature at this time was 300 ° C. As a result of this step, the first electrode layer and the third electrode layer were electrically connected via the series connection hole h1.

This first electrode layer was patterned using the second harmonic of the YAG laser, and divided into a plurality of units.

Thereafter, a current collecting hole h2 is formed by using a punch, and a photoelectric conversion layer composed of an a-Si layer is formed on the first electrode layer by a plasma CVD method. On the opposite main surface, a fourth electrode layer made of indium oxide having a low light reflectance was sequentially formed by a sputtering method.
As a result of this step, the transparent electrode layer and the fourth electrode layer were electrically connected via the current collecting hole h2.

Finally, the transparent electrode layer and the photoelectric conversion layer in the first electrode layer patterning line, and the third electrode layer
The above-mentioned method was applied to the patterning of the connection electrode layer composed of the electrode layer and the fourth electrode layer to form a thin-film solar cell in which a plurality of thin-film solar cell elements were connected in series.

As described above, by setting the number of laser pulse irradiations to four or less, it was possible to reduce the damage to the photoelectric conversion portion that occurs during laser patterning of the connection electrode layer.

[0067]

According to the present invention, as described above, in a thin-film solar cell using a substrate that transmits laser light, the material of the first and third electrode layers is a single metal of silver or aluminum. Alternatively, a material having a higher reflectivity than the fourth electrode layer, such as an alloy, is used. The material of the fourth electrode layer is a material having a lower reflectivity than the third electrode layer, such as nickel, ITO (indium tin oxide), and copper. The thickness of the first electrode layer is equal to or greater than the thickness of the third electrode layer (the invention of claim 1), and a colorant is added to absorb the laser beam. In a thin-film solar cell using a substrate to be formed, a photoelectric conversion portion is formed on the surface of the substrate on the side where the concentration of colorant is low (the invention of claim 3), so that the contact area is further increased by making the surface uneven. Thin-film sun using a polished substrate In the pond, by forming a photoelectric conversion portion on the surface on the side where the formed unevenness is large and the contact area is large (invention of claim 4), it is possible to prevent the thin film from being damaged at the time of laser patterning, A thin-film solar cell having good solar cell characteristics can be provided.

Further, in the method of manufacturing a thin-film solar cell in which the width of the patterning separation groove is widened in order to prevent a short circuit due to migration, the overlap width of the laser pulse in the laser processing line is reduced to half of the spot diameter of the laser pulse. With the following (invention of claim 5), the number of laser pulse irradiations can be limited to four or less, and damage to the photoelectric conversion unit can be eliminated.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a method for manufacturing a thin-film solar cell according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a method of manufacturing a thin-film solar cell according to another embodiment of the present invention.

FIG. 3 is a schematic diagram of a superimposed image of a laser processing line according to the present invention.

FIG. 4 is a diagram showing an example of the details of a configuration and a manufacturing method of a conventional thin film solar cell.

FIG. 5 is a perspective view showing a schematic configuration of a conventional thin-film solar cell.

FIG. 6 is a view schematically showing a manufacturing process of a conventional thin-film solar cell.

FIG. 7 is a plan view showing an example of a conventional arrangement of position detection holes, connection holes, and current collection holes in a substrate.

[Explanation of symbols]

10: substrate, a: photoelectric conversion layer, b: third electrode layer, e: fourth electrode layer, h1: connection hole, h2: current collection hole, L: first electrode layer, t: extraction electrode, u: transparent Electrode layer.

Claims (5)

[Claims] 1. A photoelectric conversion unit comprising a film substrate made of a translucent resin material, a first electrode layer as a lower electrode layer, a photoelectric conversion layer, and a transparent electrode layer (second electrode layer) sequentially laminated on a surface of the film substrate. A third connection electrode layer formed on the back surface of the substrate;
An electrode layer and a fourth electrode layer, wherein the photoelectric conversion unit and the connection electrode layer are formed by patterning a unit portion by a laser processing method while displacing the positions from each other, and an electrical series formed outside the transparent electrode layer formation region. A thin-film solar cell in which unit photoelectric conversion portions that are patterned and mutually adjacent on the surface are electrically connected in series via a connection hole for connection and a current collection hole formed in the transparent electrode layer formation region. In the material of the first electrode layer and the third electrode layer, a material having a higher reflectance than at least the fourth electrode layer, such as a single metal or alloy of silver or aluminum,
The material of the fourth electrode layer is a material having a lower reflectance than at least the third electrode layer, such as nickel, ITO (indium tin oxide), or copper, and the film thickness of the first electrode layer is A thin-film solar cell having a thickness equal to or greater than the thickness of the three electrode layers. 2. The thin-film solar cell according to claim 1, wherein the film substrate made of the light-transmitting resin material has a light transmittance of 60% or more with respect to the laser wavelength. . 3. A first electrode layer as a lower electrode layer, a photoelectric conversion layer, a first electrode layer as a lower electrode layer on a surface of a film substrate obtained by adding a coloring agent to a resin material in order to prevent transmission of a laser beam used for patterning.
A photoelectric conversion unit in which transparent electrode layers (second electrode layers) are sequentially laminated; and a third electrode layer and a fourth electrode layer serving as connection electrode layers formed on the back surface of the substrate. The connection electrode layer was patterned in a unit part by shifting the position by laser processing, and formed in the connection hole for electrical series connection formed outside the transparent electrode layer formation region and in the transparent electrode layer formation region. Through the current collection hole,
In a thin-film solar cell in which unit photoelectric conversion portions that are patterned and mutually adjacent on the surface are electrically connected in series, on the surface on the side where the colorant concentration is low in the substrate,
A thin-film solar cell comprising the photoelectric conversion unit. 4. A photoelectric conversion section comprising a film substrate made of a resin material, a first electrode layer as a lower electrode layer, a photoelectric conversion layer, and a transparent electrode layer (second electrode layer) sequentially laminated on a surface of the film substrate; A third electrode layer and a fourth electrode layer as connection electrode layers formed on the back surface of the photoelectric conversion unit and the connection electrode layer are shifted from each other and patterned into a unit portion by a laser processing method. Via a connection hole for electrical series connection formed outside the transparent electrode layer forming region and a current collecting hole formed in the transparent electrode layer forming region, the unit photoelectric conversion portions which are patterned and adjacent to each other on the surface are formed. In a thin-film solar cell electrically connected in series, the substrate is subjected to a roughening treatment on both front and rear surfaces thereof in order to improve the adhesion between the substrate and the first or third electrode layer. Contact area Wherein the photoelectric conversion portion is formed on a surface of the front or back surface, on the side having a large contact area with a large unevenness, formed. 5. A first electrode layer as a lower electrode layer, a photoelectric conversion layer, and a transparent electrode layer (second electrode layer) are sequentially laminated on a surface of a film substrate made of a resin material or a metal material coated with an electric insulation. And a third electrode layer and a fourth electrode layer as connection electrode layers formed on the back surface of the substrate, wherein the position of the photoelectric conversion unit and the connection electrode layer is shifted from each other to form a unit laser. It is patterned by a processing method, and is patterned to each other on the surface through a connection hole for electrical series connection formed outside the transparent electrode layer forming region and a current collecting hole formed in the transparent electrode layer forming region. In the method for manufacturing a thin film solar cell in which adjacent unit photoelectric conversion portions are electrically connected in series, the patterning includes forming a patterning separation groove by overlapping a plurality of laser processing lines. A method of manufacturing a thin-film solar cell, wherein the overlapping width dimension of the laser pulse in the laser processing line is not more than half the spot diameter dimension of the laser pulse.