JP2007134387A - Photoelectric conversion element and its method for forming electrode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance Voc by reducing the area of a contact region thereby reducing carrier recombination rate at the interface between a semiconductor substrate and a light receiving surface electrode, and to make a power generation layer absorb as much light as possible by reducing the area of the light receiving surface electrode on the semiconductor substrate thereby reducing reflection loss on the surface of the light receiving surface electrode. <P>SOLUTION: In the optical conversion element having a light receiving surface electrode connected electrically with a semiconductor substrate, a region where the semiconductor substrate and the light receiving surface electrode come into electrical contact is located at the outer circumferential part in the region for forming the light receiving surface electrode on the semiconductor substrate, and a region which does no come into electrical contact with the semiconductor substrate is provided in the region for forming the light receiving surface electrode on the inside of the outer circumferential part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a photoelectric conversion element and an electrode forming method thereof, and more particularly to a photoelectric conversion element used for a solar cell and the like and a method of forming an electrode thereof.

  Examples of a method for forming an electrode, which is one of solar cell manufacturing processes, include a vapor deposition method, a plating method, a printing method, and a nozzle method. At present, the screen printing method is often used from the viewpoint of cost reduction and mass productivity of solar cells.

According to this screen printing method, for n ⁺ p type solar cells, Ag conductive material prepared by mixing Ag powder, glass powder and organic resin together with a solvent when forming a light receiving surface (n ⁺ surface) electrode. The photosensitive paste is used to perform screen printing on the light receiving surface with a pattern composed of a main electrode having a width of about 1 to 2 mm and a sub electrode (grid electrode) having a width of about 50 to 200 μm in contact with the main electrode. A light-receiving surface electrode is formed by drying and baking. Conventionally, the aspect ratio (height / line width) of the sub-electrode cross section is about 0.1 to 0.2, and the resistance value per unit length of the sub-electrode is about 0.15 to 0.70 Ω / cm. is there.

  When forming the back electrode, screen printing is performed on almost the entire back surface using an Al conductive paste prepared by mixing Al powder, glass powder and organic resin together with a solvent, and then the back surface is dried and fired. An electrode is formed. At the time of forming the back surface electrode, a back surface field layer (BSF) for improving the open circuit voltage (Voc) and the short circuit current (Isc) is also formed.

  As disclosed in Patent Document 1, as a method for reducing the contact resistance between a semiconductor substrate and an electrode formed on the semiconductor substrate and increasing the adhesive strength, a first method formed in a dotted state on the semiconductor substrate is used. There is known a method of forming a second electrode that is selectively conductive with one electrode and electrically insulated from a semiconductor substrate.

As a fine electrode forming method, for example, as in Patent Document 2, there is a method in which a low melting point metal such as indium is held in a molten state and poured into a surface of a semiconductor substrate from a drawing head.
JP-A-63-1119273 JP-A-5-235388

  In order to increase the efficiency of the solar cell, it is necessary to pay attention to the following two points when forming the electrode. The first point is to enhance the effect of the insulating film that is responsible for the surface passivation formed on the surface of the semiconductor substrate. Since there is no insulating film in the region where the semiconductor substrate and the light receiving surface electrode are in electrical contact, the surface passivation effect is reduced. By reducing the area of the contact region, it is necessary to reduce the carrier recombination rate at the interface between them and improve Voc.

  Second, by reducing the area of the light receiving surface electrode on the semiconductor substrate, the reflection loss on the surface of the light receiving surface electrode is reduced and the power generation layer absorbs as much light as possible. It is necessary to take out the carriers generated by reducing the series resistance value in the current derivation direction such as the line resistance value in the length direction of the electrode without causing a resistance loss.

  From this point of view, the problem with the conventional light receiving surface electrode is that since the entire surface of the light receiving surface electrode is in contact with the semiconductor substrate, the carrier recombination speed at the interface between them increases and Voc decreases. It is that you are. In addition, it is effective to reduce the width of the light receiving surface electrode line in order to absorb much light, but at the same time, it is necessary to increase the aspect ratio of the electrode in order to prevent an increase in the resistance value of the electrode itself. However, in the current screen printing technology, if the light receiving surface electrode line width pattern is made finer, the amount of paste discharged during printing decreases, so the height of the formed electrode becomes lower, and the resistance value of the electrode itself It is also a problem that a large decrease in the fill factor (FF) value is caused by the increase in. When the light receiving surface electrode is miniaturized, the influence of the increase in the electrode line width due to the sagging of the paste becomes larger than that of the conventional light receiving surface electrode. Furthermore, since the conventional light receiving surface electrode uses a material containing a lot of glass components, the resistance value of the electrode itself increases, which causes a decrease in FF.

A practical electrode line width using the current electrode forming method is about 100 μm.
According to Patent Document 1, a first electrode formed in a scattered state on a semiconductor substrate and a method of forming a second electrode that is selectively conductive with the first electrode and electrically insulated from the semiconductor substrate are formed. By reducing the contact area and securing the cross-sectional area of the electrode, the reduction of the resistance value is suppressed and the open circuit voltage is improved. However, there is a problem in that the adhesive strength of the electrode is insufficient, causing electrode peeling. Furthermore, according to this method, in order to form the light-receiving surface electrode, two firings are necessary, and the process cost increases.

  According to Patent Document 2, an electrode line width of 100 μm or less can be formed by pouring molten metal from the drawing head onto the surface of the semiconductor substrate, but there is a problem that the electrode height is low. Moreover, there are problems that the metal to be used is limited and the cost for maintaining the melting temperature is required.

  The present invention relates to a photoelectric conversion element having a light-receiving surface electrode electrically connected to a semiconductor substrate, wherein a region where the semiconductor substrate and the light-receiving surface electrode are in electrical contact is formed on the semiconductor substrate. It is in an outer peripheral portion in the region, and has a region that is not in electrical contact with the semiconductor substrate in a region inside the outer peripheral portion in the light receiving surface electrode forming region.

  According to another aspect of the present invention, there is provided a first electrode which is an electrode formed on an outer peripheral portion in a light receiving surface electrode forming region electrically connected to a semiconductor substrate, and an inner portion of the outer periphery in the light receiving surface electrode forming region A second electrode which is an electrode formed in the region, and the first electrode and the second electrode are in electrical contact, and the second electrode has at least a glass component different from that of the first electrode, or It is preferable that the content ratio of the glass component is smaller than that of the first electrode.

  In the present invention, the aspect ratio (height / line width) of the sub-electrode cross section is preferably 0.2 or more.

  The present invention also includes a step of drawing a first electrode conductive paste on the outer peripheral portion in the light receiving surface electrode forming region on the semiconductor substrate, and a second region in the inner region from the outer peripheral portion in the light receiving surface electrode forming region. An electrode forming method including a step of drawing an electrode conductive paste.

  In the present invention, the ratio of the glass powder in the second electrode conductive paste is preferably 2 wt% or less.

  In the present invention, the second electrode conductive paste preferably has a viscosity range of 5 to 600 Pa · s at 25 ± 1 ° C.

  In the solar cell according to the present invention, the surface recombination speed and the contact resistance can be reduced while maintaining a high adhesive strength by providing a place for bonding with the semiconductor substrate in the outer peripheral portion in the light receiving surface electrode forming region, and Voc can be reduced. Can be improved. Moreover, the resistance value of the light receiving surface electrode itself can be reduced by minimizing the amount of the glass component of the entire light receiving surface electrode. Furthermore, when the line width of the sub-electrode is made fine, the first electrode conductive paste can suppress the spread of the second electrode conductive paste and increase the height of the light-receiving surface electrode. An electrode can be formed.

<Characteristics of photoelectric conversion element>
The effectiveness of the present invention from the industrial point of view will be described below in the order of the claims.

  The region where the semiconductor substrate and the light receiving surface electrode are in electrical contact is in the outer peripheral portion in the light receiving surface electrode forming region on the semiconductor substrate, and in the region inside the outer peripheral portion in the light receiving surface electrode forming region, By providing a region that is not in electrical contact with the semiconductor substrate, the area covered by the passivation film on the substrate surface in the light receiving surface electrode formation region is larger than in the case where it is in contact with the entire surface of the light receiving surface electrode formation region. The effect can be enhanced and Voc can be improved.

  When the glass components or the content ratios of the first electrode and the second electrode are different, the resistance value of the light-receiving surface electrode itself can be reduced while ensuring high adhesive strength, leading to an improvement in the FF value.

When the ratio of the glass powder in the conductive paste used in the conventional electrode is 2 wt% or less, the fire-through is insufficient and the FF is lowered. Moreover, electrode peeling will generate | occur | produce without sufficient adhesive strength being obtained. The light-receiving surface electrode of the present invention is bonded to the semiconductor substrate through a baking process with the glass powder in the first electrode conductive paste, and the second electrode conductive paste is sintered in the baking process with the first electrode conductive paste. Is done. Therefore, the glass powder in the second electrode conductive paste does not need to be fired through, and the ratio of the glass powder can be 2 wt% or less. As a result, the resistance value of the light receiving surface electrode can be reduced. Further, glass powder components that have not been used until now due to insufficient fire-through or insufficient adhesive strength, such as ZnO—SiO ₂ —B ₂ O ₃ , SnO—P ₂ O ₅ , V ₂ O ₅ —MgO. -TeO-P ₂ O ₅ or the like can also be used for the second electrode conductive paste.

  The light-receiving surface electrode has a main electrode and a sub electrode. If the aspect ratio of the sub electrode is 0.2 or more, the series resistance in the current derivation direction such as the line resistance value in the length direction of the electrode can be reduced. The FF value does not decrease.

The viscosity of the conductive paste used for the conventional electrode has such a viscosity that the conductive paste does not sag after being drawn on the semiconductor substrate. In the present invention, when drawing the second electrode conductive paste, the first electrode conductive paste already drawn on the surface of the semiconductor substrate serves as a barrier to prevent the second electrode conductive paste from spreading. Therefore, the second electrode conductive paste can have a lower viscosity than the conventional electrode paste. By setting the viscosity range of the second electrode conductive paste at 25 ± 1 ° C. to 5 to 600 Pa · s, there is no risk of disconnection during drawing, and the printability can be improved. More desirably, it is in the range of 70 to 400 Pa · s at 25 ± 1 ° C. At this time, the height of the second electrode conductive paste can be drawn high while improving the printability. Moreover, the aspect ratio exceeding 1.0 can be obtained by making the viscosity of the paste at 25 ± 1 ° C. higher than 500 Pa · s. The conductive paste includes a metal, for example, a firing paste that is fired at a high temperature of 600 ° C., a thermosetting paste that includes a metal and an epoxy resin, and is fired at a low temperature of 100 ° C., for example.
<Structure of photoelectric conversion element>
The structure of a solar cell, which is a photoelectric conversion element of the present invention, will be described with reference to the cross-sectional view of FIG. As the substrate 21, a p-type silicon substrate which is a first conductive layer obtained by slicing a cast silicon ingot by a multi-wire method, or a p-type single crystal silicon substrate sliced from a CZ method or an FZ method ingot can be used. An n-type second conductive layer 22 is formed on the light receiving surface side. An insulating film 23 having an antireflection effect is formed on the surface. The light receiving surface electrode 24 is formed by a screen printing method. The light receiving surface electrode 24 includes a first electrode 241 and a second electrode 242.

The resistance value per unit length of the electrode after firing when it is formed using the firing paste is, for example, 0.10 to 0.15 Ω / cm when the sub-electrode line width is 150 μm. On the other hand, on the back surface side, a back surface p ⁺ layer 25 and a back surface electrode 26 are formed on substantially the entire back surface of the substrate. The back surface p ⁺ layer 25 can also be configured to obtain a back surface field effect (BSF). Furthermore, it is possible to configure the back electrode 26 as a so-called back reflection layer that enhances internal reflection on the back surface.
<Process for producing photoelectric conversion element>
Next, FIG. 2 shows a flow of an entire typical solar cell manufacturing process to which the present invention can be applied. First, as the silicon mass (F-1), a mass having semiconductor characteristics obtained by the FZ method, the CZ method, the cast method, etc. is sliced and cut by a multi-wire method to form a p-type silicon plate as the first conductive layer Is prepared (F-2). Next, unevenness formation is performed on at least one side of the light incident side (F-3). Subsequently, the second conductive layer (n-type) formation (F-4), the insulating film formation (F-5), the back electrode / p ⁺ layer formation (F-6), and the light receiving surface electrode formation (F-7) are performed. To complete the solar cell. The solar cell fabrication process described above is a process that is generally used in polycrystalline silicon solar cells and the like at present, but the order can be changed and a process using vacuum can be partially used. . The electrode structure, electrode and electrode forming method of the present invention can be applied to F-7.

In the present invention, known materials such as a compound semiconductor substrate such as a silicon germanium substrate and a gallium arsenide substrate can be used in addition to the silicon substrate described above. For example, as a basic structure, n and p from the light incident side, or p and n from the light incident side are possible. Furthermore, the light incident side can be changed to n ⁺ with a high concentration instead of n, or the light incident side can be set to p ⁺ with a high concentration instead of p. These second conductive layers can also be formed by a conventionally used thermal diffusion method, ion implantation method, or the like. Further, another antireflection film may be additionally formed on the insulating film on the surface of the second conductive layer.

On the other hand, on the back surface opposite to the light incident, in addition to the above-described BSF layer, a back surface reflector is formed, and an oxide film and a nitride film are formed to prevent surface recombination. May be. Note that various oxide films can be used as the insulating film, the antireflection film, and the back surface reflection film.
<Electrode formation method>
The light-receiving surface electrode forming method according to the present invention is mainly a screen printing method, and the printing process is shown in FIG.

  FIG. 3A shows an outer peripheral portion in the light receiving surface electrode forming region 31 composed of the sub electrode forming region 311 and the main electrode forming region 312.

  FIG. 3B shows a state in which the first electrode conductive paste 32 containing glass powder in a mass ratio of 2 to 5% is printed along the light-receiving surface electrode formation region 31.

  At this time, if the line width (L2) of the sub-electrode formation region is, for example, 150 μm, the line width (L1) for drawing the first electrode conductive paste is about 50 μm. Further, if the line width (L2) of the sub-electrode formation region is, for example, 50 μm, the line width (L1) for drawing the first electrode conductive paste can be about 10 μm. Since the first electrode formed thereby is a fine electrode, the height of the electrode is about 5 μm, and the first electrode alone is not practical. As the first electrode conductive paste 32, it is preferable to use a paste having a high viscosity of 200 to 1000 Pa · s at 25 ± 1 ° C. that does not break even when drawing a fine electrode. At this time, unevenness of about several μm, which seems to be a mesh mark, may be observed at the height of the formed electrode. After printing the first electrode conductive paste 32, a drying process may be performed.

  Next, the printing position of the first electrode conductive paste is confirmed using an image including the semiconductor substrate with a CCD camera or the like provided in the screen printing machine, and the semiconductor substrate is aligned.

  FIG. 3C shows a state in which the second electrode conductive paste 33 is printed on the entire surface of the light receiving surface electrode forming region 31. At this time, in the light receiving surface electrode formed by the conventional screen printing method, for example, the method of printing the entire surface of the light receiving surface electrode forming region 31 using the first electrode conductive paste 32, the line width (L2 of the sub electrode forming region) ) Is 150 μm, the conductive paste sags, and the line width of the actually formed light-receiving surface sub-electrode widens to 170 μm, for example. However, in the present invention, when the second electrode conductive paste 33 is drawn, the first electrode conductive paste 32 has already been drawn on the semiconductor substrate, and the first electrode conductive paste 32 serves as a barrier to conduct the second electrode conductive. Since the effect of suppressing the spread of the conductive paste 33 is exhibited, no increase in the line width of the light-receiving surface electrode formed by these was observed.

  Further, at this time, if the line width (L2) of the sub-electrode forming region is 50 μm, the light receiving surface electrode formed by the usual screen printing method has an electrode height of about 5 μm, whereas in the present invention, It was possible to increase the height of the light-receiving surface electrode to 10 μm or more. This is because the height of the second electrode conductive paste 33 can be increased without sagging due to the effect of suppressing the spread of the first electrode conductive paste 32, and the semiconductor substrate and the first electrode conductivity with respect to the second electrode conductive paste 33. This is probably because the behavior of the conductive paste 32 in the plate separation process during printing differs depending on the wettability of the conductive paste 32. As the second electrode conductive paste 33, a conductive paste having a lower level of viscosity than the first electrode conductive paste 32 and good leveling properties may be selected. If the leveling property is improved, the flatness of the first electrode conductive paste 32 can be improved, and the unevenness of the second electrode conductive paste 33 can be suppressed.

  After printing the second electrode conductive paste 33, the conductive paste is dried at a low temperature, for example, about 100 ° C., and then baked at a high temperature, for example, around 700 ° C. to form a light-receiving surface electrode. In this baking process, the glass powder in the first electrode formed on the outer peripheral portion in the light receiving surface electrode forming region fires through the insulating film used as an antireflection film, so that the semiconductor substrate and the first electrode come into contact with each other. And take out the generated carrier. Further, at this time, the metal of the first electrode and the metal of the second electrode are sintered, and the first electrode and the second electrode are conducted.

  The present invention can be applied to both a main electrode and a sub electrode in an electrode of a solar cell.

In the present invention, the screen printing method is mainly used, but a nozzle method, an ink jet method, or the like is also possible. Furthermore, the material for the light-receiving surface electrode is not particularly limited as long as it includes a conductive material. For example, a metal or an alloy such as gold, platinum, silver, copper, aluminum, nickel, chromium, tungsten, iron, tantalum, titanium, or molybdenum, or a transparent conductive material such as SnO ₂ , In ₂ O ₃ , ZnO, or ITO. It can be formed by using a layer or a laminate, and a combination of the above metals and alloys. These can be formed, for example, by preparing a paste in a powder state, printing and baking the paste. The paste can be prepared, for example, by mixing metal, glass powder, organic resin, and solvent.

  The back electrode is generally formed on substantially the entire back surface, but it may be a grid-like back electrode. In this case, it is possible to form a so-called back surface reflection layer in a portion other than the grid electrode on the back surface.

Example 1
In the examples, solar cells are shown as photoelectric conversion elements. The solar cell generally has a cross-sectional structure as shown in FIG. 1, and the cell was manufactured based on the process diagram shown in FIG.

  (A) First, a p-type polycrystalline silicon substrate 21 having a sliced outer shape of 10 cm × 10 cm, a thickness of 0.35 mm, and a specific resistance of about 2 Ωcm is added in a solution obtained by adding 7% alcohol to a 5% NaOH aqueous alkali solution. The silicon surface was etched to a depth of 20 μm at 80 ° C. for 10 minutes, and surface irregularities were formed simultaneously with the removal of the crushed layer.

(B) Next, the substrate after the etching is placed on a jig in an electric furnace at 840 ° C. in an atmosphere containing POCl _3, and phosphorus diffusion is performed for 20 minutes, whereby a second conductive layer which is an n ⁺ diffusion layer 22 was formed on the silicon surface. After removing the PSG (phosphor glass) layer, etc. in an HF aqueous solution, washing and drying, the sheet resistance of the diffusion layer is 60Ω / sq, the junction depth is about 0.3 μm, and the dopant concentration near the surface is about 10 ²⁰ cm ^−3. A second conductive layer 22 on the light-receiving surface side of was obtained.

  (C) Next, a SiN layer that also functions as an antireflection film was formed as an insulating film 23 on the surface of the second conductive layer 22 using a plasma CVD apparatus. The thickness was 720 mm. Silane and ammonia were used as gas species.

(D) Next, in forming the BSF layer on the back surface, a conductive paste containing Al powder was printed and dried. Backside p ⁺ layer 25 and backside electrode 26 were obtained by firing in a near infrared furnace.

  (E) The light-receiving surface electrode was formed using a screen printing method. The line width (L1) for drawing the first electrode conductive paste to be the first electrode 241 was 50 μm. Thereafter, the first electrode conductive paste was dried at about 100 ° C. for about 5 minutes.

  (F) The second electrode 242 was formed by printing the second electrode conductive paste with a line width of 150 μm for the sub-electrode and a line width of 2.0 mm for the main electrode. The electrode pitch of the sub electrodes was 2.0 cm. Then, it was dried at about 100 ° C. for about 5 minutes and baked at about 600 ° C. for about 1 minute.

  The viscosity of the first electrode conductive paste used at this time was approximately 500 Pa · s at 25 ± 1 ° C., and the viscosity of the second electrode conductive paste was approximately 100 Pa · s at 25 ± 1 ° C. The first and second electrode conductive pastes are conductive pastes prepared by appropriately mixing silver, glass powder, organic resin, and solvent, and the glass powder contained in this conductive paste is used for conventional conductive pastes. It was the same as that. In particular, for the second electrode conductive paste, the content ratio of the glass powder was set to 1/2 that of the first electrode conductive paste. At this time, the resistance value of the light receiving surface electrode was about 0.11 Ω / cm, and the light receiving surface sub-electrode line width was about 154 μm.

Thereafter, the current-voltage characteristics of the manufactured solar cells were measured under simulated sunlight (JIS standard light AM1.5G) with an irradiation intensity of 100 mW / cm ² , and the results are shown in Tables 1 and 2.
(Comparative Example 1)
Using only the first electrode conductive paste, a light receiving surface electrode (conventional electrode) having a line width of 150 μm for the sub electrode and 2.0 mm for the main electrode was formed on the entire surface of the light receiving surface electrode forming region. At this time, the resistance value of the light-receiving surface electrode was approximately 0.14 Ω / cm. This is presumably because the resistance value of the electrode itself was increased because the entire light-receiving surface electrode contained a glass component more than necessary. The light receiving surface electrode line width was about 165 μm due to sagging of the first electrode conductive paste. The other conditions were the same as in Example 1, and the current-voltage characteristics of the solar cells were measured. The results are shown in Table 1.
(Comparative Example 2)
The first electrode was formed by drawing the first electrode conductive paste in a matrix rather than on the outer periphery in the light receiving surface electrode forming region and baking it. Then, after drawing the 2nd electrode conductive paste, it baked again and formed the light-receiving surface electrode (refer patent document 1). Both the first electrode conductive paste and the second electrode conductive paste use the same conductive paste as in Example 1, and the light receiving surface electrode patterns used are also the same as in Example 1 and Comparative Example 1. The area of the first electrode in electrical contact with the semiconductor substrate was the same as in Example 1, and the current-voltage characteristics of the solar cells were measured. The results are shown in Table 1.

From Table 1, it can be seen that Example 1 and Comparative Example 2 with less glass component in the light-receiving surface electrode have better current density (Jsc) and FF than the solar cell using the conventional electrode of Comparative Example 1. . This is because the resistance value of the electrode itself can be reduced and the contact resistance can be reduced. The Voc is improved over Comparative Example 1 because the surface recombination rate is reduced by reducing the contact area between the semiconductor substrate and the light-receiving surface electrode. In Comparative Example 2, the contact area with the semiconductor substrate was the same as that of Example 1, but the outer peripheral portion in the electrode formation region was not firmly bonded to the semiconductor substrate, so that the electrode was peeled off in the solder dipping process. In Example 1, both the main electrode and the sub-electrode have the same adhesive strength as that of the conventional electrode because the outer peripheral portion in the electrode formation region is bonded to the semiconductor substrate.
(Example 2)
In the same manner as in Example 1, the first electrode line width of the sub-electrode of the light receiving surface electrode is about 15 μm, the second electrode line width is 50 μm, the main electrode has the first electrode line width of 50 μm, and the second electrode line width is A light-receiving surface electrode was formed at 2.0 mm. The sub-electrode line width at this time was about 52 μm, and the height was about 17 μm. Further, the area of the light-receiving surface electrode was made the same as that of Example 1 by narrowing the sub-electrode pitch by the amount corresponding to the narrower sub-electrode line width.

The pseudo solar light of a radiation intensity 100 mW / cm ² (JIS standard light AM1.5G), to measure the current-voltage characteristics of the fabricated solar cell. The results are shown in Table 2.
(Comparative Example 3)
With the same light receiving surface electrode pattern as in Example 2, a light receiving surface electrode was formed using only the first electrode conductive paste. At this time, the sub-electrode line width was about 56 μm and the height was about 6 μm. Further, the current-voltage characteristics of the solar cells were measured in the same manner as in Example 2, and the results are shown in Table 2.

  From Table 2, the present invention was able to form a practical fine electrode, and a higher FF value than Example 1 could be obtained by narrowing the electrode pitch. In Comparative Example 3, the sub electrode line width was fine, but since the height of the sub electrode was low, the resistance value of the light receiving surface electrode itself increased and the FF value significantly decreased.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  In the solar battery cell based on this invention, Voc can be improved. Further, by minimizing the amount of glass component in the entire light receiving surface electrode, the resistance value of the light receiving surface electrode itself can be reduced, and a practical fine electrode can be formed.

It is sectional drawing of the solar cell structure of this invention. It is a flowchart of the whole solar cell preparation process. It is a top view of a part of electrode which shows the printing process which forms the electrode of this invention. It is sectional drawing of the solar cell which shows the photovoltaic cell preparation process process of this invention.

Explanation of symbols

21 Substrate, 22 Second conductive layer, 23 Insulating film, 24 Light receiving surface electrode, 241 First electrode, 242 Second electrode, 25 Back surface p ⁺ layer, 26 Back surface electrode, 31 Light receiving surface electrode formation region, 311 Sub electrode formation region , 312 Main electrode forming region, 32 First electrode conductive paste, 33 Second electrode conductive paste, L1 Line width for drawing first electrode conductive paste, L2 Line width of sub electrode forming region.

Claims (6)

A photoelectric conversion element having a light-receiving surface electrode electrically connected to a semiconductor substrate,
The region where the semiconductor substrate and the light-receiving surface electrode are in electrical contact is in the outer peripheral portion in the light-receiving surface electrode forming region on the semiconductor substrate, and in the region inside the outer peripheral portion in the light-receiving surface electrode forming region A photoelectric conversion element having a region that is not in electrical contact with a semiconductor substrate.   A first electrode which is an electrode formed on an outer peripheral portion in a light receiving surface electrode forming region electrically connected to a semiconductor substrate; and an electrode formed in a region inside the outer peripheral portion in the light receiving surface electrode forming region And the first electrode and the second electrode are in electrical contact with each other, and at least the glass component of the second electrode is different from the first electrode or the glass component The photoelectric conversion element according to claim 1, wherein the content ratio of is less than that of the first electrode.   3. The photoelectric conversion according to claim 1, wherein the light-receiving surface electrode includes a main electrode and a sub electrode, and an aspect ratio (height / line width) of the sub-electrode cross section is 0.2 or more. element. It is the electrode formation method of the photoelectric conversion element of Claim 2, Comprising:
Drawing the first electrode conductive paste on the outer peripheral portion in the light receiving surface electrode forming region on the semiconductor substrate, and drawing the second electrode conductive paste in the region inside the outer peripheral portion in the light receiving surface electrode forming region An electrode forming method comprising the step of:   The electrode forming method according to claim 4, wherein a ratio of the glass powder in the second electrode conductive paste is 2 wt% or less.   6. The electrode forming method according to claim 4, wherein a viscosity range of the second electrode conductive paste at 25 ± 1 ° C. is 5 to 600 Pa · s.

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