JPH09260703A - Solar battery cell and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate connection of solar battery cells by electrically separating a main diffusion layer in a region used for photoelectric transfer from a sub- diffusion layer in a region used for extraction of electrode, by a mechanical cutting means and extracting electrodes from a semiconductor substrate by diffusing impurities inside of a recess in the region where the sub-diffusion layer exists. SOLUTION: An n+ diffusion layer 3 and a metal oxide layer (antireflection film) 2 are formed on the light receiving side of a substrate. On one end of the substrate, a cut recess 4 is formed in the antireflection film 2 and the n+ diffusion layer 3 by a dicing saw, etc. The recess 4 is cut deeper than the depth of the n+ diffusion layer 3. Several recesses 4 are formed continuously by the dicing saw, etc. By this method, the n+ diffusion layer 3 is electrically separated into an n+ diffusion layer 3a (a main diffusion layer) which will become a main light receiving face and an n+ diffusion layer 3b (a sub-diffusion layer) which will become an extraction plus electrode region.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a solar cell,
In particular, the present invention relates to a structure of a solar cell having an electrode structure that can be easily connected in series and a manufacturing method thereof.

[0002]

2. Description of the Related Art A conventional manufacturing process flow of a solar battery cell is shown in FIG. 11, and a schematic sectional view showing the main manufacturing process of the solar battery cell is shown in FIG. The manufacturing process will be described below step by step.

In FIG. 11, the flow of the conventional manufacturing process of a solar battery cell is as follows: texture etching, application of a diffusion source, formation of an n-type diffusion layer, silver electrode printing on the back surface, aluminum electrode printing on the back surface, silver on the light receiving surface. It consists of electrode printing, firing, and solder dipping.

In FIG. 12 (a), reference numeral 50 denotes a p-type silicon semiconductor substrate which is a substrate of a solar cell, and generally has an impurity concentration of 3 × 10 ¹⁵ to 4 × 10 ¹⁶ cm ^-3 and a crystal plane of (100 ) Is used. On the light receiving surface of the silicon substrate 50, in order to reduce surface reflection of light, a fine pyramidal uneven surface called a textured surface is formed. The enlarged surface is shown in the circle.

The process of obtaining this textured surface is a texture etch, in which isopropyl alcohol is added to a solution containing several% of NaOH (caustic soda) and the temperature is set to 80 ° C.
It is formed by processing a silicon substrate 50 having a (100) plane for 20 to 30 minutes at a temperature in the range of to 90 ° C.

In FIG. 12B, a metal oxide also serving as an antireflection film is applied to the light receiving surface side of the silicon semiconductor substrate 50 by using a roll coater or a spin coater. This metal oxide contains an n-type impurity such as a phosphorus compound. This step is the application of the diffusion source. Then, heat treatment is performed at a temperature of about 900 ° C. to form an n + diffusion layer 51 having a diffusion depth of about 0.4 μm. This is n
This is the process of forming the mold diffusion layer.

Next, on the back surface of the silicon semiconductor substrate 50, a back surface silver electrode 52 acting as a plus electrode is formed as shown in FIG. Then, the back surface aluminum electrode 53 is formed on most of the back surface except the area of the back surface silver electrode 52. Since the back surface silver electrode 52 and the back surface aluminum electrode 53 are electrically connected to each other, they have a partially overlapped structure. These steps are a back surface silver electrode printing step and a back surface aluminum electrode printing step.

Next, a silver electrode 54 acting as a negative electrode is formed on the light receiving surface side. The electrodes on the back surface side and the electrodes on the light receiving surface side are formed by patterning a paste containing silver or aluminum by screen printing or the like. Then, by drying and baking at a temperature of 700 to 800 ° C., a p + diffusion layer 55 having a thickness of about 5 μm is formed under the aluminum electrode 53 on the back surface. Further, the silver electrode 54 on the light receiving surface side penetrates an antireflection film (not shown) and makes ohmic contact with the n + diffusion layer 51. This heat treatment is a firing process.

Finally, the silver electrode 54 on the light-receiving surface side and the back surface silver electrode 52 are dipped in a solder bath at about 190 ° C. for about 20 minutes.
The solar cell is completed by being covered with a solder layer having a thickness of μm. This process is a solder dipping process.

[0010]

However, the conventional series connection of solar cells has the following problems.

Since the output voltage of one silicon solar battery cell is approximately 0.4 to 0.5 V, it is general to connect a plurality of solar battery modules in series in order to obtain a high voltage. In the conventional solar cell, the negative electrode extracted from the n + diffusion layer is formed on the light receiving surface side (front side) of the solar cell, while the positive electrode extracted from the p-type semiconductor substrate (bulk) is formed on the back surface side of the solar cell. Therefore, when performing the series connection, it is necessary to connect the minus electrode on the front side and the plus electrode on the back side of the adjacent solar cell with a metal piece such as an interconnector. Therefore, in the process of connecting in series, it is necessary to connect interconnectors to the front side and the back side of the solar cells separately, which is a major obstacle to automation.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method of manufacturing a solar battery cell which can be easily connected.

[0013]

A solar cell according to claim 1 of the present invention has a positive electrode and a negative electrode arranged on the light-receiving surface side, and a diffusion layer formed on the light-receiving surface side is photoelectric. The main diffusion layer in the region used for conversion and the sub-diffusion layer in the region used for electrode extraction are electrically separated by a mechanical cutting means, and the sub-diffusion layer formed by the mechanical cutting means It is characterized in that the electrode is taken out from the semiconductor substrate by diffusing impurities into the groove.

The solar cell according to claim 2 of the present invention has a positive electrode and a negative electrode arranged on the light receiving surface side, and the diffusion layer formed on the light receiving surface side is subjected to photoelectric conversion. The main diffusion layer in the region to be taken out and the sub-diffusion layer in the region to be taken out of the electrode are electrically separated, and the electrode from the semiconductor substrate is removed by the through diffusion of impurities of the conductivity type which is electrically opposite to the diffusion layer. It is characterized by the fact that it has started.

In the solar cell according to claim 3 of the present invention, the positive electrode and the negative electrode are arranged on the light receiving surface side, and the aluminum diffusion layer is provided on the back surface side of the substrate facing the light receiving surface. It is characterized in that an aluminum electrode is provided.

According to a fourth aspect of the present invention, in the method of manufacturing a solar cell, the positive electrode and the negative electrode are arranged on the light receiving surface side, and the diffusion layer provided for photoelectric conversion on the light receiving surface side. In the step of forming, the electrical separation between the main diffusion layer in the region used for photoelectric conversion of the diffusion layer formed on the light-receiving surface side and the sub-diffusion layer in the region used for electrode extraction is performed by mechanical cutting means. And a step of making ohmic contact with the semiconductor substrate by diffusing impurities into the groove formed by the mechanical cutting means.

Further, in the method for manufacturing a solar cell according to claim 5 of the present invention, the plus electrode and the minus electrode are arranged on the light receiving surface side, and the diffusion layer provided for photoelectric conversion on the light receiving surface side. Forming the diffusion layer formed on the light-receiving surface side into a main diffusion layer in a region used for photoelectric conversion and a sub-diffusion layer in a region used for electrode extraction, and the sub-diffusion. And a step of making ohmic contact with the semiconductor substrate by penetrating diffusion of an impurity having a conductivity type that is electrically opposite to that of the layer.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 10 are diagrams relating to an embodiment of the present invention. The manufacturing process flow of the solar battery cell of the present invention is shown in FIG. 2, a plan view of the light receiving surface side of the solar battery cell is shown in FIG.
FIG. 1B is a sectional view taken along the line AA ′ of FIG. 1A, and an enlarged view of the positive electrode lead-out portion of the solar cell is shown in FIG.
It is shown in (c). Further, FIG. 3 shows a schematic cross-sectional view showing the main manufacturing steps of the solar battery cell. The manufacturing process will be described below step by step.

In FIG. 2, the flow of the manufacturing process of the solar cell of the present invention is as follows: texture etching, diffusion source coating, n-type diffusion layer formation, groove formation, aluminum electrode printing on the back side, light receiving surface side. It consists of silver electrode printing, firing, and solder dip. FIG. 1 shows a flow of a conventional manufacturing process of a solar cell.
Compared with 1, there is no silver electrode printing step on the back surface, and a groove forming step is newly added.

Explaining in relation to the claims, in the manufacturing process of the solar cell of the present invention, (1) application of a diffusion source and formation of an n-type diffusion layer are performed on the light receiving surface side which is used for photoelectric conversion. And (2) the groove is formed by mechanical cutting means for electrically separating the main diffusion layer in the region used for photoelectric conversion from the sub-diffusion layer in the region used for electrode extraction. (3) Printing of the aluminum electrode on the back surface side, printing of the silver electrode on the light receiving surface side, and baking are performed by diffusion of impurities into the groove of the sub-diffusion layer region formed by a mechanical cutting means. To take out the electrode from.

In FIG. 3, which is a schematic sectional view showing the main manufacturing steps of the solar battery cell of the present invention, reference numeral 1 in FIG.
Is a p-type silicon semiconductor substrate which is a substrate of a solar cell, and generally has an impurity concentration of about 3 × 10 ¹⁵ to 4 × 10 ^16.
cm ⁻³ , and (100) is used for the crystal plane. In the case of the embodiment of the present invention, the size of the silicon substrate 1 is, for example, about 25 mm to 150 mm in length, about 25 mm to 150 mm in width, and 0.3 mm to 0.5 in thickness.
mm. In order to reduce surface reflection of light, a fine pyramid-shaped uneven surface called a textured surface is formed on the light receiving surface of the silicon substrate 1. The enlarged surface is shown in the circle. The process of obtaining this textured surface is texture etching, and while adding isopropyl alcohol in a solution containing several% of NaOH (caustic soda),
It is formed by treating the silicon substrate 1 having a (100) plane at a temperature in the range of 80 ° C. to 90 ° C. for 20 to 30 minutes.

In FIG. 3B, the metal oxide 2 which also serves as an antireflection film is applied to the light receiving surface side of the silicon semiconductor substrate 1 by a device such as a roll coater or a spin coater.
This metal oxide contains an n-type impurity such as a phosphorus compound. This step is the application of the diffusion source. Then 9
Heat treatment is performed at a temperature of around 00 ° C and the diffusion depth is about 0.4μ.
An n + diffusion layer 3 of about m is formed. This is the step of forming the n-type diffusion layer.

In FIG. 3C, the substrate 1 is provided on the light receiving surface side.
An n + layer 3 and a metal oxide layer (antireflection film) 2 are formed on the top surface. A groove cut into the antireflection film 2 and the n + diffusion layer 3 at a position of about 1 mm to 5 mm from one end (the left end in FIG. 3) of the substrate 1 by, for example, a dicing saw (a cutting machine that cuts by rotating a diamond wheel). 4 is formed. This groove is formed deeper than the depth of the n + diffusion layer 3 and has a depth of about 10 μm or more. In succession, groove 4 with a dicing saw
Put a few bottles. As a result, the n + diffusion layer 3 is electrically separated into the n + diffusion layer 3a (main diffusion layer) that serves as the main light receiving surface and the n + diffusion layer 3b (sub diffusion layer) that serves as the extraction plus electrode region. This step is a groove forming step. The size of the groove 4 created by cutting with a dicing saw is
For example, it has a width of about 0.3 mm to 0.6 mm and is formed from one end to the other along one side of the wafer. In addition, the size of the n + diffusion layer 3b serving as the extraction plus electrode region is
For example, in the case of a 125 mm square wafer, the width is about 3 mm to 6 m.
m, and, after all, the ratio of the extraction plus electrode region to one wafer is about 2.0% to 5.0%, and there is little influence on the reduction of the light conversion efficiency with respect to the entire area of the wafer. .

In FIG. 3 (d), a paste containing aluminum is printed by screen printing or the like on almost the entire inside of the back surface aluminum electrode 5 except about 2 mm to 4 mm around the back surface of the silicon substrate 1. This step is the back surface aluminum electrode printing step. Next, the silicon substrate 1
Similarly, a paste containing silver is printed on the surface (light receiving surface side) by screen printing. The electrode printing with this silver paste is composed of two patterns, one of which is for the negative current collector silver electrode 6 on the n + diffusion layer 3a which is the main light-receiving surface, and the other one is for the positive electrode 7. This is for the groove 4 formed in the previous step. This step is a silver electrode printing step on the light receiving surface side. The width of the groove 4 is about 0.3 mm
Since the thickness is about 0.6 mm, the printed silver paste penetrates into the inside of the groove 4 and directly contacts the p-type silicon substrate.

In FIG. 3 (e), each of the printed pastes is then dried to about 1 ° C at a temperature of 700 ° C to 800 ° C in a gas atmosphere in which nitrogen gas is mixed with oxygen gas.
By firing for about 0 minutes, a p + diffusion layer 8 having a thickness of about 5 μm is formed under the aluminum electrode 5 on the back surface. The p + diffusion layer causes the BSF effect, and the aluminum electrode on the back surface acts as a means for reducing the series resistance of the solar battery cell. Also, the collecting silver electrode 6 on the light-receiving surface side
The silver penetrates the antireflection film and makes ohmic contact with the n + diffusion layer 3a. At the same time, since the silver electrode 7 on the light receiving surface side is formed so as to penetrate into the inside of the groove 4, this heat treatment makes ohmic contact with the p-type silicon substrate 1. This time,
The n + diffusion layer 3b is divided by the groove 4 and is destroyed, so that it does not act electrically. This step is a firing step.

Finally, in FIG. 3 (f), about 190 ° C.
The positive side silver electrode 7 and the negative side current collecting silver electrode 6 on the front side of the solder layer (each having a thickness of 7 μm).
The solar cell is completed by coating (solder coat) with H and 6H). This process is a solder dipping process.

FIG. 1 is a diagram of a solar cell according to an embodiment of the present invention according to the description with reference to FIGS. In FIG. 1 (a), reference numeral 2 denotes an antireflection film provided on the light receiving surface side of the solar cell, and the light receiving surface covers a fine pyramidal uneven surface called a textured surface. Reference numeral 6 denotes a solder-coated current collecting electrode on the light-receiving surface, which is composed of thin branch current collecting electrodes 6b arranged at substantially equal intervals and a trunk current collecting electrode section 6a for collecting electricity from the thin current collecting electrode section 6b. There is.

FIG. 1 (b) is a sectional view taken along the line AA 'in FIG. 1 (a). 1 is a p-type silicon semiconductor substrate which is a substrate of a solar battery cell, and generally has an impurity concentration of about 3
× 10 ¹⁵ to 4 × 10 ¹⁶ cm ⁻³ , and the crystal plane is (100). On the light-receiving surface side of the silicon crystal substrate 1, there are an n + diffusion layer 3, an antireflection film 2 and collector electrodes 6a and 6b.
Furthermore, there is an upper surface plus electrode 7 electrically separated by the groove 4. FIG. 1C is an enlarged view of the upper surface plus electrode 7. Further, on the back surface side, there are the p + diffusion layer 8 and the aluminum electrode 5.

In the case of a 125 mm square wafer, the characteristics of the solar cell obtained in the case of the embodiment of the present invention are as follows: open-circuit voltage V _OC = 0.4.0 at light intensity AM 1.5 (1000 W / cm ² ). 62V, short circuit current I _SC = 5.0
8 A, optimum operating voltage Vpm = 0.48 V, optimum operating current Ipm = 4.73 A (about 30 mA / cm ² ), maximum output Pm = 2.27 W, fill factor FF = 0.72,
Light conversion efficiency Eff = 14.5%, area of sub-diffusion layer = 12
5 mm × 4 mm, and in this case, the extraction plus electrode region (area of the sub diffusion layer) occupying the wafer was about 3.2%.

FIG. 4 shows the relationship between the conversion efficiency and the area of the sub-diffusion layer in a solar cell having a cell size of 125 mm square. Area of sub-diffusion layer is 0mm ² , 400mm ² , 800m
The light conversion efficiency is 15.0% for m ^{2 and 1} for m ² .
It is 4.63% and 14.24%.

A solar cell of the present invention according to another embodiment will be described. The difference from the present invention described above with reference to FIG. 1 is how to take out the plus electrode. The silver electrode 7 on the light-receiving surface side penetrates into the inside of the groove 4 and is heat-treated to make ohmic contact with the p-type silicon substrate 1 In contrast to the electrode, the positive electrode is taken out by ohmic contact between the p + layer formed of aluminum paste on the light-receiving surface side and the p-type silicon substrate 1. The description will be made in the following order.

The flow of the manufacturing process of the solar cell of the present invention is as follows: texture etching, diffusion source coating, n-type diffusion layer formation, groove formation, aluminum electrode printing on the back surface side, aluminum paste printing on the light receiving surface side, It consists of silver paste printing, baking, and solder dip on the light-receiving surface side.

Explaining in relation to the claims, in the manufacturing process of the solar cell of the present invention, (1) application of a diffusion source and formation of an n-type diffusion layer are formed on the light-receiving surface side which is used for photoelectric conversion. And (2) the formation of the groove is to electrically separate the main diffusion layer in the region used for photoelectric conversion and the sub-diffusion layer in the region used for electrode extraction. 3) Printing of aluminum electrodes on the back surface side, printing of aluminum paste on the light receiving surface side, printing of silver paste on the light receiving surface side, and baking are performed to penetrate the diffusion layer of impurities of a conductivity type that is electrically opposite to that of the diffusion layer, thereby removing electrodes from the semiconductor substrate. To take it out.

FIG. 5 (a) shows a plan view of the solar cell of the present invention on the light-receiving surface side, and FIG. 5 (b) is a sectional view of the solar cell taken along the line BB 'in FIG. 5 (a). ), And an enlarged view of the positive electrode extraction portion of the solar cell is shown in FIG. Further, FIG. 6 shows a schematic cross-sectional view showing the main manufacturing steps of the solar battery cell. The manufacturing process will be described below step by step.

In FIG. 6, which is a schematic sectional view showing the main manufacturing steps of the solar battery cell of the present invention, reference numeral 1 in FIG.
Is a p-type silicon semiconductor substrate which is a substrate of a solar cell, and generally has an impurity concentration of about 3 × 10 ¹⁵ to 4 × 10 ^16.
cm ⁻³ , and (100) is used for the crystal plane. In order to reduce surface reflection of light, a fine pyramid-shaped uneven surface called a textured surface is formed on the light receiving surface of the silicon substrate 1. The enlarged surface is shown in the circle.

In FIG. 6B, the metal oxide 2 which also serves as an antireflection film is applied to the light receiving surface side of the silicon semiconductor substrate 1 by a device such as a roll coater or a spin coater.
This metal oxide contains an n-type impurity such as a phosphorus compound. This step is the application of the diffusion source. Then 9
Heat treatment is performed at a temperature of around 00 ° C and the diffusion depth is about 0.4μ.
An n + diffusion layer 3 of about m is formed. This is the step of forming the n-type diffusion layer.

In FIG. 6C, the substrate 1 is provided on the light receiving surface side.
An n + layer 3 and a metal oxide layer (antireflection film) 2 are formed on the top surface. Grooves cut into the antireflection film 2 and the n + diffusion layer 3 at a position about 4 mm to 6 mm from one end (the left end in FIG. 3) of the substrate 1 by, for example, a dicing saw (a cutting machine that cuts by rotating a diamond wheel). 4 is formed. This groove is formed deeper than the depth of the n + diffusion layer 3 and has a depth of about 10 μm or more. As a result, the n + diffusion layer 3 becomes the main light receiving surface and the n + diffusion layer 3 becomes the extraction plus electrode region.
electrically separated from b. This step is a groove forming step.

In FIG. 6 (d), a paste containing aluminum is printed by screen printing or the like on almost the entire inside of the back surface aluminum electrode 5 except about 2 mm to 4 mm around the back surface of the silicon substrate 1. This step is the back surface aluminum electrode printing step.

Next, n + which becomes the extraction plus electrode region
A paste containing aluminum is printed on the upper surface of the diffusion layer 3b except for about 1 mm to 2 mm from one end of the groove 4 by screen printing or the like. This is the aluminum paste layer 9 on the light-receiving surface side that serves as a p + diffusion source. This process is the aluminum paste printing process on the light receiving surface side.

Further, in FIG. 6 (d), next, a paste containing silver is printed on the surface (light-receiving surface side) of the silicon substrate 1 by screen printing as well. Electrode printing with this silver paste consists of two patterns,
One of them is for the negative collector silver electrode 6 to the n + diffusion layer 3a which becomes the main light-receiving surface, and the other one is for the positive electrode, the pattern of the aluminum paste layer 9 on the light-receiving surface side formed in the previous step. The silver base 10 is printed with an overlap of about 1 mm to 3 mm. This step is a silver paste printing step on the light receiving surface side.

In FIG. 6E, next, each printed paste is dried and baked at a temperature of 700 ° C. to 800 ° C. for about 10 minutes in a mixed gas atmosphere of nitrogen gas and oxygen gas. Thus, the p + diffusion layer 8 having a thickness of about 5 μm is formed under the aluminum electrode 5 on the back surface. Further, silver of the current collecting silver electrode 6 on the light receiving surface side penetrates the antireflection film and makes ohmic contact with the n + diffusion layer 3a. At the same time, the aluminum of the aluminum paste layer 9 on the light receiving surface side serves as a p + diffusion source, and the n + layer 3 (diffusion depth of about 0.4 μm) on the light receiving surface.
And a p + diffusion layer 11 (about 5 μm) is formed to make ohmic contact with the p-type silicon substrate 1. This step is a firing step.

Finally, in FIG. 6 (f), about 190 ° C.
The solar battery cell is completed by immersing in the solder bath of No. 1 and covering the minus collector silver electrode 6 and the plus silver electrode 10 on the surface side with a solder layer (6H and 10H, respectively) having a thickness of about 20 μm. This process is a solder dipping process.

FIG. 5 shows a solar cell according to an embodiment of the present invention according to the description with reference to FIG. FIG.
In (a), 2 is an antireflection film provided on the light-receiving surface side of the solar battery cell, and the light-receiving surface covers a fine pyramidal uneven surface called a textured surface. Reference numeral 6 denotes a solder-coated current collecting electrode on the light-receiving surface, which is composed of thin branch current collecting electrodes 6b arranged at substantially equal intervals and a trunk current collecting electrode section 6a for collecting electricity from the thin current collecting electrode section 6b. There is.

FIG. 5 (b) is a sectional view taken along the line BB 'in FIG. 1 (a). 1 is a p-type silicon semiconductor substrate which is a substrate of a solar battery cell, and generally has an impurity concentration of about 3
× 10 ¹⁵ to 4 × 10 ¹⁶ cm ⁻³ , and the crystal plane is (100). On the light-receiving surface side of the silicon crystal substrate 1, there are an n + diffusion layer 3, an antireflection film 2 and collector electrodes 6a and 6b.
In addition there is a top positive electrode 10 electrically isolated by the groove 4. FIG. 5C is an enlarged view of the upper surface plus electrode 10. Also, on the back surface side, the p + diffusion layer 8,
There is an aluminum electrode 5.

Next, series connection (modularization) of the solar cells thus obtained will be described with reference to FIGS. 7 to 10.

FIG. 7 shows a solar cell manufactured by the method shown in FIG. 1 or 5 in which the positive electrode 7 or 10 is arranged on the upper side of a quadrangle, and the solar cell of the present invention has a light receiving surface. A plan view of the side is shown in FIG. 7A, and a sectional view of the solar cell is shown in FIG. 7B. The light receiving surfaces 12 of the plurality of solar cells are connected in series by an interconnector 13. The interconnector 13 is U-shaped, and the trunk collector electrode portion 6 of the negative electrode 13a and the negative electrode 13a connected to the positive electrode (7 or 10) via the solder layer.
a and 13b connected via a solder layer. As shown in FIG. 7B, the so-called front connection is achieved by using the configuration of the present invention. In FIG. 7, the thin collector electrode portion 6b is not shown. Further, the interconnector 13 is about 0.1 mm
A thin copper foil piece of about 0.3 mm coated with a solder is used.

The trunk collector electrode portion 6c of the collector electrode 6 on the light-receiving surface side of the solar battery cell shown in FIG. 8 is formed parallel to one side of the solar battery cell, and the plus electrode and the minus electrode are the solar battery cell. They are arranged on opposite sides. 6b is a thin collector electrode part. An example of the case where the solar cells are connected in series is shown in FIGS. 9 and 10.

In FIG. 9, the solar battery cell is shown in FIG.
As shown in FIG. 5, the plus electrodes 7 and the minus electrodes 6 are arranged at positions that are alternately aligned. FIG. 9B is connected by a single-character interconnector 15. On the right side of the solar cell, first, the negative electrode 6 is connected to the interconnector 15 via the solder layer 6H.
Is connected to Next, on the left side of the solar cell, the plus electrode 7 is connected to the interconnector 15 via the solder layer 7H, and the interconnector 15 is connected to the minus electrode 6 via the solder layer 6H. .
Then, on the right side of the solar cell, the minus electrode 6 is connected to the interconnector 15 via the solder layer 6H, and the interconnector 15 is connected to the plus electrode 7 via the solder layer 7H. . In this way,
The series connection of solar cells is completed. 14 is a light receiving surface of a plurality of solar cells.

In FIG. 10, the solar cell is shown in FIG.
As shown in (a), the positive electrode 7 and the negative electrode 6 are arranged at positions facing each other. FIG.
(B) is connected by a short U-shaped interconnector 16. On the side of the solar cell, first, the negative electrode 6 is connected to the interconnector 1 via the solder layer 6H.
6 and the interconnector 16 is connected to the plus electrode 7 via the solder layer 7H. By repeating this connection, the series connection of the solar cells is completed.

Thus, as shown in FIGS. 7, 9 and 10, by using the solar battery cell of the present invention, so-called front connection is achieved.

[0051]

As described above, according to the solar cell in which the positive electrode and the negative electrode according to claim 1 of the present invention are arranged on the light receiving surface side, the diffusion layer formed on the light receiving surface side is used for photoelectric conversion. The electrical diffusion between the main diffusion layer in the region to be provided and the sub diffusion layer in the region to be used for electrode extraction is performed by mechanical cutting means, and the groove of the sub diffusion layer region formed by the mechanical cutting means is formed. By taking out the electrode from the semiconductor substrate by diffusing the impurities into the interior, it is possible to obtain a solar battery cell that can be easily connected in series without significantly impairing the conversion efficiency.

Further, according to the solar battery cell of the present invention in which the plus electrode and the minus electrode are arranged on the light-receiving surface side, the diffusion layer formed on the light-receiving surface side can be used for photoelectric conversion. By electrically separating the main diffusion layer and the sub-diffusion layer in the region used for electrode extraction, and by extracting the electrode from the semiconductor substrate by through diffusion of impurities of a conductivity type that is electrically opposite to the diffusion layer, It is possible to obtain a solar battery cell that can be easily connected in series without significantly impairing the conversion efficiency.

According to the third aspect of the present invention, since the aluminum electrode having the aluminum diffusion layer is provided on the back surface of the substrate facing the light receiving surface, the BSF effect and the bulk resistance can be suppressed low. The problem of taking out the positive electrode from the end of the solar cell can be solved.

According to the fourth aspect of the present invention, according to the method for manufacturing a solar cell in which the plus electrode and the minus electrode are arranged on the light receiving surface side, the diffusion layer used for photoelectric conversion is formed on the light receiving surface side. Step, a step of electrically separating the diffusion layer formed on the light-receiving surface side from the main diffusion layer in the area used for photoelectric conversion and the sub-diffusion layer in the area used for electrode extraction by a mechanical cutting means, By including a step of making ohmic contact with the semiconductor substrate by diffusing impurities into the groove formed by the mechanical cutting means, a method for manufacturing a solar battery cell that is easy to connect in series without significantly impairing conversion efficiency. Obtainable.

Further, according to the method for manufacturing a solar cell in which the plus electrode and the minus electrode are arranged on the light receiving surface side according to the fifth aspect of the present invention, the diffusion layer used for photoelectric conversion is formed on the light receiving surface side. Step, electrically separating the diffusion layer formed on the light-receiving surface side into a main diffusion layer in a region used for photoelectric conversion and a sub-diffusion layer in a region used for electrode extraction. By including the step of making ohmic contact with the semiconductor substrate by penetrating diffusion of impurities of opposite conductivity type, it is possible to obtain a method of manufacturing a solar battery cell that can be easily connected in series without significantly impairing conversion efficiency.

As described above, according to the present invention, since both the negative electrode and the positive electrode of the solar battery cell are on the light receiving surface side, when connecting in series with the interconnector, as shown in FIG.
As shown in FIGS. 9 and 10, serial connection is possible only by the process of connecting from the light-receiving surface side, so that the work of connecting the interconnector becomes easy and the process can be automated. Further, conventionally, the number of steps of forming an electrode has been three, that is, a silver electrode on the back surface, an aluminum electrode, and a silver electrode on the light receiving surface. According to the present invention, the aluminum electrode on the back surface and the silver on the light receiving surface are required. The electrode only needs to be provided twice, and the process can be simplified.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a solar battery cell according to an embodiment of the present invention, in which (a) is a plan view of a light receiving surface,
(B) is an AA 'sectional view of (a), (c) is an enlarged view of the positive electrode extraction part of a photovoltaic cell.

FIG. 2 is a manufacturing process flow chart of the solar cell of the present invention.

FIG. 3 is a process cross-sectional view for explaining the method for manufacturing a solar cell according to the embodiment of the present invention, in which (a) is a cross-sectional view of a p-type silicon semiconductor substrate which is a substrate of the solar cell. 3A and 3B are enlarged views showing a textured surface, a texture etching step, (b) a diffusion source applying step and an n-type diffusion layer forming step, (c) a groove forming step, and (d) a backside aluminum. It is a figure which shows an electrode printing process and the process of silver electrode printing of the light-receiving surface side, (e) a baking process, and (f) a solder dipping process.

FIG. 4 is a diagram showing the relationship between the size of the sub-diffusion layer region and the conversion efficiency of the solar cell according to the embodiment of the present invention.

5A and 5B are views for explaining a solar cell according to another embodiment of the present invention, in which FIG. 5A is a plan view of a light-receiving surface, and FIG. 5B is a cross section taken along the line BB ′ of FIG. FIG. 1C is an enlarged view of the positive electrode extraction portion of the solar cell.

FIG. 6 is a process cross-sectional view for explaining the method for manufacturing a solar cell according to the embodiment of the present invention, in which (a) is a cross-sectional view of a p-type silicon semiconductor substrate which is a substrate of the solar cell. 3A and 3B are enlarged views showing a textured surface, a texture etching step, (b) a diffusion source applying step and an n-type diffusion layer forming step, (c) a groove forming step, and (d) a backside aluminum. Electrode printing step, light receiving surface side aluminum paste printing step and light receiving surface side silver paste printing step, (e)
FIG. 4A is a diagram showing a firing step, and FIG.

FIG. 7 is a diagram for explaining series connection (modularization) of solar cells according to an embodiment of the present invention,
This is an example using a U-shaped interconnector, (a)
Is a plan view before connection, and (b) is a plan view after connection.

FIG. 8 is a plan view on a light-receiving surface side of a solar cell according to another embodiment of the present invention.

FIG. 9 is a diagram for explaining a series connection (modularization) of solar cells according to another embodiment of the present invention, which is an example using a one-shaped interconnector;
(A) is a plan view before connection, (b) is a plan view after connection.

FIG. 10 is a diagram for explaining a series connection (modularization) of solar cells according to another embodiment of the present invention, which is another example using a one-shaped interconnector, (A) is a plan view before connection, (b) is a plan view after connection.

FIG. 11 is a manufacturing process flow chart of a conventional solar cell.

FIG. 12 is a process sectional view (a) to (e) for explaining a conventional method for manufacturing a solar cell.

[Explanation of symbols]

1 p-type silicon semiconductor substrate which is a substrate of a solar cell 2 metal oxide also serving as an antireflection film 3 n + diffusion layer 3a main diffusion layer (n + diffusion layer) 3b in a region used for photoelectric conversion 3b electrode extraction Sub-diffusion layer (n +
Diffusion layer 4 Groove 5 Aluminum electrode 6 Negative collector silver electrode on the light-receiving side 6H Solder layer of negative collector silver electrode 6a Negative collector silver electrode 6 trunk collector part 6b Negative collector silver electrode 6 branch Collection electrode part 7 Plus silver electrode 7H Plus Solder layer of silver electrode 7 Aluminum p + diffusion layer on the back surface 9 p + Aluminum paste layer on the light-receiving surface side that serves as a diffusion source 10 Silver paste layer (plus electrode) on the light-receiving surface side 10H Plus Solder layer 11 of silver electrode 11 p + diffusion layer that penetrates through n + layer 3 on the light-receiving surface 12 Light-receiving surface of a solar cell 13 U-shaped interconnector 13a Interconnector connected to the plus electrode and the solder layer 13b Part of the interconnector connected to the negative electrode via the solder layer 14 Photoreceptive surface of solar cell 15 Interconnector 16 Interconnect Ta

Claims (5)

[Claims] 1. In a solar cell in which a plus electrode and a minus electrode are arranged on the light-receiving surface side, a diffusion layer formed on the light-receiving surface side is used for taking out a main diffusion layer and an electrode in a region for photoelectric conversion. The region from the semiconductor substrate is electrically separated from the sub-diffusion layer by a mechanical cutting means, and the electrode is removed from the semiconductor substrate by diffusing impurities into the groove of the sub-diffusion layer region formed by the mechanical cutting means. A solar cell characterized by being launched. 2. In a solar cell in which a plus electrode and a minus electrode are arranged on the light-receiving surface side, a diffusion layer formed on the light-receiving surface side is used for taking out a main diffusion layer and an electrode in a region for photoelectric conversion. A solar cell, wherein the electrode is taken out from the semiconductor substrate by electrically separating into a sub-diffusion layer in a region defined by the diffusion layer, and through diffusion of impurities of a conductivity type electrically opposite to the diffusion layer. 3. The solar cell according to claim 1, wherein an aluminum electrode having an aluminum diffusion layer is provided on the back surface side of the substrate facing the light receiving surface. 4. A method of manufacturing a solar cell in which a plus electrode and a minus electrode are arranged on the light-receiving surface side, in the step of forming a diffusion layer used for photoelectric conversion on the light-receiving surface side, and forming on the light-receiving surface side. The step of electrically separating the main diffusion layer in the area used for photoelectric conversion of the diffusion layer and the sub-diffusion layer in the area used for electrode extraction by a mechanical cutting means, formed by a mechanical cutting means And a step of making ohmic contact with the semiconductor substrate by diffusing impurities into the inside of the groove. 5. A method for manufacturing a solar cell in which a plus electrode and a minus electrode are arranged on the light-receiving surface side, in the step of forming a diffusion layer used for photoelectric conversion on the light-receiving surface side, and on the light-receiving surface side. A step of electrically separating the diffusion layer into a main diffusion layer in a region used for photoelectric conversion and a sub-diffusion layer in a region used for electrode extraction; A method of manufacturing a solar cell, comprising a step of making ohmic contact with a semiconductor substrate by through diffusion.