JP2009283558A - Solar cell, its method for manufacturing, and solar cell system equipped with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-efficiency and high-reliability solar cell in which a plated projection part caused by characteristic degradation in a high-humidity environment in the solar cell after an optical silver plating process is removed; and its method for manufacturing. <P>SOLUTION: This method of manufacturing this solar cell is characterized by including processes of: forming a second conductivity type high-concentration diffusion layer on a light reception surface side of a first conductivity type crystal silicon substrate; forming an antireflection film on the second conductivity type high-concentration diffusion layer; applying an electrode material onto the antireflection film and on a light non-reflection surface side of the crystal silicon substrate to respectively form a front baked electrode constituting a front electrode and a back baked electrode acting as a back electrode by subjecting obtained coatings to a heat treatment; forming an optical silver plated layer to overlap the front baked electrode by an optical silver plating method to obtain the front electrode comprising the front based electrode and the optical silver plated layer; forming a mask with a resin material to overlap the optical silver plated layer; electrically peeling a projection part at an end of the optical silver plated layer by an optical silver plating method; and peeling the mask. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a highly reliable solar cell that uses a crystalline silicon substrate and that is highly reliable in which deterioration of characteristics under a high humidity environment is suppressed, a method for manufacturing the solar cell, and a solar cell system including the solar cell. More specifically, the present invention relates to a solar cell including a plating electrode that promotes low resistance and is covered with a fired electrode in a non-contact manner, and a manufacturing method thereof, and a solar cell system including the solar cell.

In recent years, expectations for solar cells that directly convert solar energy into electrical energy have increased rapidly as a next-generation energy source particularly from the viewpoint of the global environment.
Such solar cells have been developed using various materials such as silicon semiconductors, compound semiconductors, and organic materials. Currently, solar cells using single crystal silicon or polycrystalline silicon silicon semiconductors are available. It has become mainstream.
FIG. 1A to FIG. 1F are schematic cross-sectional views illustrating an example of a manufacturing process in a conventional solar cell manufacturing method.

First, as shown in FIG. 1A, a monocrystalline or polycrystalline silicon substrate 1 previously doped with atoms (dopants) of the first conductivity type is prepared.
Next, as shown in FIG. 1B, a high-concentration diffusion layer 2 containing a dopant of the second conductivity type is formed on the light-receiving surface side of the crystalline silicon substrate 1, and p as shown in FIG. -N junction 3 is obtained.

Next, as shown in FIG. 1D, an antireflection film 4 is formed on the crystalline silicon substrate 1 by, for example, a plasma CVD method (P-CVD method) or the like.
Next, as shown in FIG. 1E, for example, an electrode material is applied to the light-receiving surface side and the non-light-receiving surface side by a screen printing method or the like, and heat treatment is performed. Get.

By this heat treatment, the front surface fired electrode 5 penetrates the antireflection film 4 as shown in FIG. 1E and comes into contact with the high-concentration diffusion layer 2 (fire through). Are diffused into the crystalline silicon substrate 1 to form a BSF (Back Surface Field) layer 7.
The BSF layer 7 is a layer in which a dopant is distributed at a high concentration in a semiconductor near the backside firing electrode 6, forms a built-in electric field near the backside firing electrode 6, and generates electrons near the backside firing electrode 6 by the electric field. Is pushed toward the surface of the semiconductor substrate 1 to suppress surface recombination loss and improve the performance of the solar cell.

As a method for improving the photoelectric conversion efficiency (also simply referred to as “conversion efficiency”) of the solar cell thus manufactured, for example, a method for reducing shadow loss in the surface fired electrode 5, for example, the surface fired electrode 5 One example is miniaturization.
At present, the electrode width of the surface firing electrode 5 in the solar cell using the silicon semiconductor which is the mainstream is about 100 μm to about 70 μm, and by reducing the width to about 70 μm, the reduction of shadow loss is expected and the conversion efficiency is improved. Can be achieved. However, with the miniaturization of the surface-fired electrode 5, the conductor resistance loss, that is, the direct current resistance component is increased, the short-circuit current is reduced, and a result contradicting the high conversion efficiency of the solar cell is obtained.

As one measure to solve this problem, for example, A.Mette et al., "Increasing the Efficiency of Screen-Printed Silicon Solar Cells by Light-Induced Silver Plating ^{", 2006 IEEE 4 th WCPEC, Hawaii} ( Non-Patent Document 1), Japanese Examples thereof include “photosilver plating” as described in Japanese Unexamined Patent Application Publication No. 2004-266023 (Patent Document 1) and Japanese Unexamined Patent Application Publication No. 2004-193337 (Patent Document 2).

FIG. 2 is a schematic view showing the principle of the photosilver plating method.
According to this photosilver plating method, for example, by irradiating light 11 (fluorescent lamp light) through a plating solution 13 containing potassium hydroxide as a main component, the surface firing electrode 5 is brought to a negative potential due to the photovoltaic effect. Further, silver ions are deposited from the silver bar 12 that is positively biased with respect to the back-surface fired electrode 6 in the plating solution 13, and the surface-fired electrode 5 is densely placed on the surface-fired electrode 5 without contact with the silver bar 12. A high-purity photosilver plating layer (not shown, see FIG. 3 in FIG. 3) is formed, and as a result, the electrode resistance is reduced.
In FIG. 2, reference numeral 1 denotes a crystalline silicon substrate, 4 denotes an antireflection film, 9 denotes a cathode electrode roller, 10 denotes a conveyor roller, and 16 denotes a variable DC power source.

Japanese Patent Laid-Open No. 2004-266023 JP 2004-193337 A A. Mette et al., “Increasing the Efficiency of Screen-Printed Silicon Solar Cells by Light-Induced Silver Plating”, 2006 IEEE 4th WCPEC, Hawaii

When the inventor of the present invention actually tried the above-described photosilver plating method with an experimental machine, the result was that the maximum output Pm of the solar cell after silver plating was improved by 3.5% compared to that without silver plating. was gotten.
However, when a solar cell in which the electrode is silver-plated by this photosilver plating method is exposed to a high-humidity environment, the solar cell characteristics tend to deteriorate. When the inventor of the present invention investigated the cause, as shown in FIG. 3, the plating solution remains at the end of the plating that grows isotropically, that is, the plating overhang (plating eaves) 14, and the residue It was inferred that the plating solution 13-1 had an adverse effect on the surface fired electrode 5 and the antireflection film 4 (crystal silicon substrate interface), and caused a deterioration in the characteristics of the solar cell.

  The present invention provides a high-efficiency and high-reliability solar cell from which a plating overhang caused by characteristic deterioration in a high-humidity environment has been removed in a solar cell after photosilver plating treatment and a method for producing the same. Let it be an issue.

  As a result of diligent research to solve the above-mentioned problems, the present inventor narrowed the width of the photosilver plating electrode overlaid on the surface firing electrode (underlying electrode), thereby preventing the plating solution from remaining. It has been found that a highly efficient and highly reliable solar cell can be obtained, and the present invention has been completed.

Thus, according to the present invention,
(1) forming a second conductivity type high-concentration diffusion layer on the light-receiving surface side of the first conductivity type crystalline silicon substrate;
(2) forming an antireflection film on the high-concentration diffusion layer of the second conductivity type;
(3) An electrode material is applied on the antireflection film and on the non-light-receiving surface side of the crystalline silicon substrate, the obtained coating film is subjected to a heat treatment, and a surface fired electrode and a back electrode respectively constituting the surface electrode; Forming a back-fired electrode,
(4) A step of forming a photosilver plating layer so as to overlap the surface firing electrode by a photosilver plating method to obtain a surface electrode composed of the surface firing electrode and the photosilver plating layer;
(5) forming a mask with a resin material so as to overlap the photosilver plating layer;
(6) A step of electrically peeling off the overhanging portion of the end of the photosilver plating layer by a photosilver plating method, and (7) a method of producing a solar cell, comprising the step of peeling off the mask. Provided.

Moreover, according to the present invention, obtained by the above solar cell manufacturing method,
A second conductivity type high-concentration diffusion layer, an antireflection film and a surface electrode on the light receiving surface side of the first conductivity type crystalline silicon substrate, and a back electrode on the non-light receiving surface side of the crystal silicon substrate;
The surface electrode comprises a surface fired electrode formed by coating and heat treatment and a photosilver plating layer formed so as to overlap the fired electrode by a photosilver plating method, and the photosilver is formed by mask formation and peeling treatment. A solar cell is provided in which the protruding portion at the end of the plating layer is removed.

  Furthermore, according to this invention, a solar cell system characterized by including said solar cell is provided.

According to the present invention, there is provided a highly efficient and highly reliable solar cell from which a plating overhang caused by characteristic deterioration in a high-humidity environment is removed in a solar cell after photosilver plating, and a method for manufacturing the solar cell. be able to.
That is, according to the present invention, in a solar cell using a crystalline silicon substrate, the output is improved (higher efficiency) by improving the electrode aspect ratio by the photosilver plating method, and the protruding portion at the end of the photosilver plating layer is removed. Long-term reliability can be ensured.
In addition, according to the present invention, a solar cell and a solar cell that meet the unit price of watts while utilizing the existing manufacturing process of combining a known photosilver plating method with a conventional manufacturing process of a solar cell using a crystalline silicon substrate The system can be mass-produced.

The method for producing the solar cell of the present invention comprises:
(1) forming a second conductivity type high-concentration diffusion layer on the light-receiving surface side of the first conductivity type crystalline silicon substrate;
(2) forming an antireflection film on the high-concentration diffusion layer of the second conductivity type;
(3) An electrode material is applied on the antireflection film and on the non-light-receiving surface side of the crystalline silicon substrate, the obtained coating film is subjected to a heat treatment, and a surface fired electrode and a back electrode respectively constituting the surface electrode; Forming a back-fired electrode,
(4) A step of forming a photosilver plating layer so as to overlap the surface firing electrode by a photosilver plating method to obtain a surface electrode composed of the surface firing electrode and the photosilver plating layer;
(5) forming a mask with a resin material so as to overlap the photosilver plating layer;
(6) A step of electrically peeling off the protruding portion at the end of the photosilver plating layer by a photosilver plating method, and (7) a step of peeling off the mask.

Although the manufacturing method of the solar cell of this invention is demonstrated using drawing, this invention is not limited by this description.
1 (a) to 1 (g) and FIGS. 4 (h) to (j) are schematic cross-sectional views illustrating an example of a manufacturing process in the method for manufacturing a solar cell of the present invention. 1A to 1F overlap with the manufacturing steps in the conventional solar cell manufacturing method. Hereinafter, each step will be described in detail.

(1) Step of forming second conductivity type high-concentration diffusion layer 2 on the light-receiving surface side of first conductivity type crystal silicon substrate 1 Crystal silicon substrate 1 as shown in FIG. Any of the polycrystalline silicon substrates may be used, and the resistance value and the crystal orientation in the case of a single crystal are not particularly limited. The conductivity type may be either p-type or n-type. For example, a p-type crystal silicon substrate doped with Al as the first conductivity type dopant is often used.
The crystalline silicon substrate 1 is preferably etched using a suitable etchant to have a light confinement effect, and has fine irregularities of about several μm on the surface.
The thickness of the crystalline silicon substrate 1 is about 0.16 to 0.2 mm.

  As shown in FIG. 1B, a high concentration diffusion layer 2 is formed on the light receiving surface side of the crystalline silicon substrate 1 by a known method. For example, when a p-type crystalline silicon substrate is used, a silicon compound material containing phosphorus in the crystalline silicon substrate 1 by applying an aqueous solution containing phosphorus as an n-type dopant (for example, an aqueous phosphoric acid solution) and heating. A high-concentration diffusion layer 2 is formed to obtain a pn junction 3 as shown in FIG.

The phosphoric acid (H ₃ PO ₄ ) aqueous solution can be prepared by mixing phosphoric acid and pure water, and the phosphoric acid concentration is preferably 1 to 12% by weight, and the n-type semiconductor layer formed after heating Considering to improve the uniformity in the wafer surface, 2 to 8% by weight is particularly preferable.
A known method can be applied as a method of applying the phosphoric acid aqueous solution. For example, a spray method, a spin coating method, a roll coating method and the like can be mentioned, and the spin coating method is particularly preferable in that the solution can be uniformly applied on the wafer surface relatively easily.

  As a heating method, for example, it is preferable to heat the crystalline silicon substrate 1 at a temperature of 150 to 300 ° C., dry the phosphoric acid aqueous solution coating film, and then heat it in a high temperature furnace at a temperature of 700 to 1000 ° C. Due to the heating in the high temperature furnace, phosphorus atoms of phosphoric acid adhering to the surface of the crystalline silicon substrate 1 diffuse into the crystalline silicon substrate 1.

Further, instead of the above phosphoric acid aqueous solution, a solution containing phosphotitanium glass (PTG) may be used for a single crystal silicon substrate, and phosphorus silicide glass (PSG) may be used for a polycrystalline silicon substrate.
The film thickness of the high-concentration diffusion layer 2 is about 0.1 to 0.5 μm.
In order to remove metal impurities on the surface of the crystalline silicon substrate 1 after the formation of the pn junction 3 and before the formation of the antireflection film 4, it is preferable to perform an HF cleaning process.

(2) Step of forming the antireflection film 4 on the second conductivity type high-concentration diffusion layer 2 As shown in FIG. 1D, in order to effectively capture light such as sunlight, the second conductivity type An antireflection film (also referred to as “surface reflection film”) 4 is formed on the high concentration diffusion layer 2.
A known material can be applied as the material of the antireflection film. For example, silicon oxide, silicon nitride, silicon carbide, titanium oxide and the like can be mentioned, and among these, silicon nitride which is widely used is particularly preferable.
A known method can be applied as the formation method. For example, a plasma CVD method (P-CVD method), a catalytic CVD method, and the like can be given, and a P-CVD method that can be continuously processed and is suitable for mass production is particularly preferable.

For example, the conditions for forming the silicon nitride film as the antireflection film 4 by the P-CVD method may be appropriately set depending on the shape of the reaction chamber, etc. For example, monosilane 10 to 500 sccm, ammonia 10 to 1000 sccm, and nitrogen 50 to 1000 sccm. In the case of the mixed gas, it is desirable that the pressure is in the range of 10 to 200 Pa and the temperature is in the range of 200 to 600 ° C. Under such formation conditions, excellent characteristics can be imparted to the silicon nitride film.
The thickness of the antireflection film may be appropriately set according to the refractive index of the film and the size of the surface irregularities of the crystalline silicon substrate 1, but is usually about 60 to 100 nm.

(3) An electrode material is applied on the antireflection film 4 and on the non-light-receiving surface side of the crystalline silicon substrate 1, and the obtained coating film is subjected to a heat treatment to form a surface fired electrode 5 and a back surface, respectively, constituting the surface fired electrode Step of Forming Backside Burning Electrode 6 that Becomes a Firing Electrode As shown in FIG. 1E, a surface firing electrode 5 is formed on the antireflection film 4.
Known materials and methods can be applied as the material and formation method. For example, a conductive paste mainly composed of silver powder, glass powder, organic vehicle, and organic solvent is applied (printed) on the antireflection film by screen printing, and dried at a temperature of 100 to 400 ° C.
The pattern is not particularly limited, and is not particularly limited as long as it is a pattern generally used for solar cells. For example, a fish bone type (comb shape) is mentioned, and the width is usually about 100 to 160 μm although it depends on the pattern.

Further, as shown in FIG. 1 (e), a back-surface fired electrode 6 is formed on the non-light-receiving surface side of the crystalline silicon substrate 1. The back-fired electrode 5 is used for taking out the carriers generated in the crystalline silicon substrate 1 as a current.
Known materials and methods can be applied as the material and formation method. For example, a conductive paste containing aluminum powder or the like is applied (printed) to the entire back surface of the solar cell by screen printing and dried at a temperature of 100 to 400 ° C. The screen printing method is preferable because the cost can be reduced at the mass production level.

After forming the coating film to be the front firing electrode 5 and the back firing electrode 6, as shown in FIG. 1 (f), the crystalline silicon substrate 1 is subjected to a firing treatment to form the front firing electrode 5 and the back firing electrode 6. A BSF (Back Surface Field) layer 7 is simultaneously formed at the fire through surface firing electrode 5 and at the interface between the crystalline silicon substrate 1 and the back firing electrode 6.
The fire-through is a phenomenon that occurs when the antireflection film 4 is broken by the action of the glass powder added to the surface firing electrode 5 when the crystalline silicon substrate 1 is fired. Thereby, the surface firing electrode 5 can be brought into contact with the high concentration diffusion layer 2 of the crystalline silicon substrate 1.

The back-side fired electrode 6 is a region in which a part of aluminum contained in the back-side fired electrode is diffused into the crystal silicon substrate 1 when the crystal silicon substrate 1 is fired. It is possible to improve the collection efficiency of careers.
The firing conditions are preferably a temperature range of 600 to 900 ° C. and a firing time of about 1 to 300 seconds.
The thickness of the surface firing electrode 5 and the back surface firing electrode 6 is usually about 10 to 60 μm.

(4) Step of forming a photosilver plating layer 8 so as to overlap the surface fired electrode 5 by a photosilver plating method to obtain a surface electrode composed of the surface fired electrode and the photosilver plating layer as shown in FIG. As shown in FIG. 1 (g), a photosilver plating layer 8 is formed on the surface firing electrode 5 by the “photosilver plating method”. The film thickness (plating thickness) of the photosilver plating layer 8 is about 2.0 to 6.0 μm.
In the photosilver plating method, for example, by irradiating light 11 (fluorescent lamp light) through a plating solution 13 containing potassium hydroxide as a main component, the surface firing electrode 5 becomes a negative potential due to the photovoltaic effect. Silver ions are precipitated from the silver bar 12 that is positively biased with respect to the back-surface fired electrode 6 in the plating solution 13, and the surface fired electrode 5 is dense and highly pure on the surface fired electrode 5 without contact with the silver bar 12. A photosilver plating layer 8 is formed.

(5) A step of forming the mask 15 with a resin material so as to overlap the photosilver plating layer 8 (mask processing step)
As shown in FIG. 4 (h), a mask 15 having the same or slightly narrower width as the surface firing electrode 5 is formed on the photosilver plating layer 8. The width of the photosilver plating layer 8 is about 0.02 to 0.085 times the width of the surface firing electrode 5.
As the resin material, known materials can be applied, and among these, polyvinyl alcohol, polyvinyl acetate, epoxy resin, and alkali-resistant plating resist material are particularly preferable.
As a method for forming the mask, known methods can be applied, and among these, a screen printing method, an ink jet printing method, and adhesive tape sticking are particularly preferable.

(6) Step of electrically peeling off the overhanging portion 14 at the end of the photosilver plating layer 8 by the photosilver plating method (plating overhanging portion removing treatment step)
With the “photosilver plating method” as shown in FIG. 2, as shown in FIG. 4 (i), the bias of the silver bar 12 with respect to the surface fired electrode composed of the surface fired electrode 5 and the photosilver plating layer 8 is set to a negative potential, The plating overhanging portion 14 is electrically peeled off (stripped).

(7) Process of peeling the mask 15 (mask peeling process)
Finally, as shown in FIG. 4J, the mask is peeled off by a known method. Among these, a combination of organic peeling and acetone cleaning or direct peeling is preferable.

  In the solar cell obtained by the above steps, (A) the area in the height direction of the surface fired electrode 5 is enlarged, the aspect ratio is increased, current flows easily, and (B) the plating overhanging portion 14 is removed. Therefore, the shadow loss is about the same as that before the photosilver plating treatment, and (C) the plating solution residual 13-1 of the plating overhanging portion 14 is eliminated, thereby suppressing the deterioration of characteristics of the solar cell in a high humidity environment. Can do.

The solar cell of the present invention is obtained by the above solar cell production method,
A second conductivity type high-concentration diffusion layer, an antireflection film and a surface electrode on the light receiving surface side of the first conductivity type crystalline silicon substrate, and a back electrode on the non-light receiving surface side of the crystal silicon substrate;
The surface electrode comprises a surface fired electrode formed by coating and heat treatment and a photosilver plating layer formed so as to overlap the fired electrode by a photosilver plating method, and the photosilver is formed by mask formation and peeling treatment. The overhanging portion at the end of the plating layer is removed.

Moreover, the solar cell system of this invention is equipped with said solar cell, It is characterized by the above-mentioned.
Examples of such a solar cell system include a solar cell panel, a solar illumination lamp, and an information display using a module in which the solar cells of the present invention are connected in series and / or in parallel.

  The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the examples.

Example 1
The solar cell of this invention was produced according to the process shown to Fig.1 (a)-(g) and FIG.4 (h)-(j).
First, a p-type polycrystalline silicon substrate 1 having a thickness of about 0.2 mm as shown in FIG.
Next, as shown in FIG. 1B, a solution containing phosphorus silicide glass (PSG) is applied to the light-receiving surface side of the p-type polycrystalline silicon substrate 1 by spin coating, and heat treatment is performed at about 900 ° C. for 60 minutes. And phosphorus is diffused as an n-type dopant in the p-type crystalline silicon substrate 1 to form a high-concentration diffusion layer 2 having a film thickness of about 0.3 μm. As shown in FIG. An n-junction 3 was obtained.
Next, in order to remove metal impurities on the surface, HF cleaning treatment was performed.

Next, as shown in FIG. 1D, an antireflection film 4 made of a silicon nitride film having a thickness of about 70 nm was formed on the p-type polycrystalline silicon substrate 1 in the vacuum chamber of the P-CVD apparatus.
The mixed gas flow rate ratio during the formation of the antireflection film 4 was monosilane: ammonia: nitrogen = 1: 2: 12. The other film formation conditions were a frequency of 13.56 MHz, a film formation pressure of 100 Pa, a film formation temperature of 450 ° C., and a film formation time of 225 seconds.

  Next, as shown in FIG. 1E, a silver paste mainly composed of silver powder, glass powder, organic vehicle and organic solvent is applied on the antireflection film 4 of the p-type polycrystalline silicon substrate 1 by screen printing. It printed with the fish-bone type pattern, and it dried sufficiently at the temperature of 150 degreeC, and formed the 30-micrometer-thick layer. In addition, the fish-bone type pattern used was formed by bus bar electrodes (main grid) and finger electrodes (sub grid), and the finger electrodes were arranged perpendicular to the two bus bar electrodes.

Next, as shown in FIG. 1E, an aluminum paste is printed on the non-light-receiving surface side of the p-type polycrystalline silicon substrate 1 by a screen printing method and sufficiently dried at a temperature of 150 ° C. to form a layer having a thickness of 40 μm. Formed.
Next, the p-type polycrystalline silicon substrate 1 is subjected to a baking process at a temperature of 850 ° C. for 120 seconds using a near-infrared furnace, and a surface baking electrode 5 having an electrode height of 25 μm and a width of 100 μm and a backside baking electrode having an electrode thickness of 60 μm. As shown in FIG. 1 (f), a BSF layer 7 was formed at the fire-through of the front surface fired electrode 5 and at the interface between the p-type polycrystalline silicon substrate 1 and the back surface fired electrode 6.

Next, as shown in FIG. 1G, a photosilver plating layer 8 having a film thickness of about 3 μm was formed by the “photosilver plating method” as shown in FIG.
Next, as shown in FIG. 4 (h), a mask 15 about 0.7 times the width of the surface firing electrode 5 (about 70 μm) is used on the photosilver plating layer 8 by an adhesive tape sticking method using a Kapton tape. Formed.
Next, the overhanging portion 14 at the end of the photosilver plating layer 8 was electrically peeled off by a photosilver plating method.
Next, the mask 15 was peeled off by a combination of organic peeling and acetone cleaning, to obtain a solar cell of the present invention.

Using a solar simulator, the obtained solar cell was irradiated with simulated light of AM 1.5 and 100 mW / cm ² (temperature condition: 25 ° C.), and the conversion efficiency (%) was measured. As a result, it was 15.4%. It was.

(Comparative Example 1)
Except not performing the process shown in FIG.1 (g) and FIG.4 (h)-(j), when the solar cell was produced similarly to Example 1 and the conversion efficiency (%) was measured, it was 14 9%.

(Comparative Example 2)
A solar cell was produced in the same manner as in Example 1 except that the steps shown in FIGS. 4H to 4J were not performed, and the conversion efficiency (%) was measured. As a result, it was 15.6%. .

From the obtained results, the solar cells of Example 1 and Comparative Example 2 having the photosilver plating layer have an output (calculated from the conversion efficiency) improved by 3% or more compared to the solar cell of Comparative Example 1. I understand.
When the solar cells of Example 1 and Comparative Example 2 were kept in a high humidity environment (temperature 85 ° C., humidity 85%) and the conversion efficiency (%) was measured, they were 15.4% and 14.6%, respectively. It was.
Moreover, when the surface electrode of the solar cell of Example 1 and Comparative Example 2 was observed, the remaining plating solution was observed in the latter, but not in the former.
From these results, in the solar cell of Comparative Example 2, it is surmised that the residual plating solution has an adverse effect on the surface-fired electrode 5 and the antireflection film 4 and causes the characteristics of the solar cell to deteriorate.

A schematic sectional view showing an example of a manufacturing process ((a) to (f)) in a conventional solar cell manufacturing method and a manufacturing process (after (g) photosilver plating method treatment) in the solar cell manufacturing method of the present invention. It is a schematic sectional drawing which shows an example. It is the schematic which shows the principle of a photosilver plating method. It is an expanded sectional view of the vicinity of the surface baking electrode and photosilver plating layer in the solar cell of this invention. It is a schematic sectional drawing which shows an example of the manufacturing process ((h)-(j)) in the manufacturing method of the solar cell of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crystalline silicon substrate of 1st conductivity type 2 High concentration diffusion layer of 2nd conductivity type 3 pn junction 4 Antireflection film (surface reflection film)
5 Surface firing electrode 6 Back surface firing electrode 7 BSF layer 8 Photosilver plating layer 9 Cathode electrode roller 10 Conveyor roller 11 Light (fluorescent lamp light)
12 Silver Bar 13 Plating Solution 13-1 Residual Plating Solution 14 Plating Overhang (Plating Eaves)
15 Mask 16 Variable DC power supply

Claims (7)

(1) forming a second conductivity type high-concentration diffusion layer on the light-receiving surface side of the first conductivity type crystalline silicon substrate;
(2) forming an antireflection film on the high-concentration diffusion layer of the second conductivity type;
(3) An electrode material is applied on the antireflection film and on the non-light-receiving surface side of the crystalline silicon substrate, the obtained coating film is subjected to a heat treatment, and a surface fired electrode and a back electrode respectively constituting the surface electrode; Forming a back-fired electrode,
(4) A step of forming a photosilver plating layer so as to overlap the surface firing electrode by a photosilver plating method to obtain a surface electrode composed of the surface firing electrode and the photosilver plating layer;
(5) forming a mask with a resin material so as to overlap the photosilver plating layer;
(6) A step of electrically peeling off the protruding portion at the end of the photosilver plating layer by a photosilver plating method, and (7) a step of peeling off the mask.   The method for producing a solar cell according to claim 1, wherein the resin material in the step (5) is polyvinyl alcohol, polyvinyl acetate, an epoxy resin, or an alkali-resistant plating resist material.   The method for manufacturing a solar cell according to claim 1 or 2, wherein the mask forming method in the step (5) is a screen printing method, an ink jet printing method, or an adhesive tape sticking.   The peeling of the projecting portion at the end of the photosilver plating layer in the step (6) is an electrical peeling by a photosilver plating method in which a bias of the silver bar with respect to the back electrode is a negative potential. The manufacturing method of the solar cell as described in any one.   The method for manufacturing a solar cell according to any one of claims 1 to 4, wherein the mask peeling in the step (7) is a combination of organic peeling and acetone cleaning or direct peeling. Obtained by the method for producing a solar cell according to any one of claims 1 to 5,
A second conductivity type high-concentration diffusion layer, an antireflection film and a surface electrode on the light receiving surface side of the first conductivity type crystalline silicon substrate, and a back electrode on the non-light receiving surface side of the crystal silicon substrate;
The surface electrode comprises a surface fired electrode formed by coating and heat treatment and a photosilver plating layer formed so as to overlap the fired electrode by a photosilver plating method, and the photosilver is formed by mask formation and peeling treatment. A solar cell, wherein an overhang portion at an end of a plating layer is removed.   A solar cell system comprising the solar cell according to claim 6.