KR102314772B1 - Solar cell and manufacturing method of solar cell - Google Patents

Abstract

(Objective) The present invention relates to a solar cell and a method for manufacturing a solar cell, wherein a ribbon is directly soldered to a finger electrode on the surface of a silicon substrate (1) to reduce the resistance component and also to reduce electron leakage. , the objective is to firmly fix the ribbon by directly soldering it to the nitride film.
(Configuration) Soldering a lead wire with solder over the portion with the finger electrode and the portion of the insulation film without the finger electrode with a constant width b in the direction perpendicular to the finger electrode that draws electrons from the region formed on the insulating film, It is configured so that electrons from the finger electrodes are extracted to the outside by the lead wire and the lead wire is fixed to the substrate.

Description

Solar cell and manufacturing method of solar cell

The present invention forms a region that generates a high electron concentration when irradiated with light or the like on a substrate, and an insulating film that transmits light or the like is formed on the region, A conventional bus bar electrode, in which a finger electrode forming an extraction port for withdrawing electrons from the region is formed on the upper portion, and also electrically connecting a plurality of finger electrodes to withdraw electrons to the outside The present invention relates to a solar cell and a method for manufacturing a solar cell in which glass-free, direct solder connection to a finger electrode and direct solder connection from a substrate on the back surface is performed.

In the conventional design of a solar cell, it is very important to efficiently flow electrons generated in the solar cell to an external circuit connected thereto. In order to achieve this, it is particularly important to make the resistive component of the portion continuous from the cell to the outside, to prevent the generated electrons from being lost, and to firmly fix the external terminals on the front and back surfaces.

For example, as shown in the prior art in Fig. 12, a nitride film 22 is formed on the surface (upper surface) of the silicon substrate 21, and a paste of a finger electrode (silver) 23 is applied thereon. A finger electrode 23 that screen-prints and sinters lead glass (including lead glass), and draws electrons from the high electron concentration region to the outside by drilling a hole in the nitride film 22 as shown in the figure. to form Next, the bus bar electrode (silver) 24 is screen-printed and sintered in a direction orthogonal to the finger electrode 23 to produce it. A ribbon (lead wire) 25 was soldered on the bus bar electrode (silver) 24 with a solder 26 , and the ribbon 25 was firmly fixed to the silicon substrate 21 .

Further, an aluminum electrode 27 was formed on the back surface (lower surface) of the silicon substrate 21, and a ribbon was soldered to it and fixed.

In addition, in the case where the aluminum electrode 27 is formed on the entire surface, when the soldering strength of the ribbon 29 is weak, a hole (the portion corresponding to the bus bar electrode 24 on the surface) is formed in a part of the aluminum electrode 27. A hole was drilled in the hole, and silver paste was screen-printed thereto and sintered to form a silver portion 271, and the ribbon 29 was fixed thereto with solder 28 to obtain the necessary fixing strength. .

However, the bus bar electrode (silver) 24 is formed on the surface of the conventional silicon substrate 21 described above to collect electrons from a plurality of finger electrodes 23, or the ribbon 25 is connected to the bus bar electrode ( Since it was necessary to firmly solder the silicon substrate 21 through the silver 24, the bus bar electrode 24 needs to be formed of silver or a paste containing a lot of silver, and in addition to the paste When lead glass is contained, there is a problem that electrons collected in the bus bar electrode 24 leak toward the silicon substrate 21 due to sintering or the like.

In addition, when the aluminum electrode is formed on the entire surface of the back surface of the silicon substrate 21 and the ribbon is soldered thereon, there is a problem that the ribbon cannot be fixed to the silicon substrate 21 with sufficient strength in some cases.

In addition, in order to avoid this, it is necessary to make a hole in a part of the aluminum electrode 27 as shown in FIG. 12 described previously, apply silver paste thereto and sinter it, and solder a ribbon thereon to obtain sufficient fixing strength. There was also the problem of throwing it away.

The present inventors pay attention to the fact that the upper portion of the finger electrode on the surface of the silicon substrate 1 is exposed on the insulating film, and directly solder an external terminal strip ribbon to the exposed upper portion of the finger electrode to form a resistive component A configuration and method have been discovered that can reduce the amount of power and electron leakage and firmly solder the ribbon directly to the nitride film or through glass.

Further, the present inventors have discovered a structure and method for obtaining sufficient fixing strength by drilling a hole in an aluminum electrode or a part of an aluminum electrode on the back surface of a silicon substrate and directly soldering to the aluminum electrode or a part of the hole in the aluminum electrode.

Therefore, in the present invention, a region generating high electron concentration when irradiated with light or the like is formed on the substrate, an insulating film that transmits light or the like is formed on the region, and on the insulating film, an extraction port for extracting electrons from the region In the solar cell forming a finger electrode and withdrawing electrons to the outside through the finger electrode, the finger electrode having a constant width (b) in a direction orthogonal to the finger electrode withdrawing electrons from a region formed on the insulating film, a portion having a finger electrode; A leader wire is soldered with solder over a portion of the insulating film without a finger electrode, and electrons from the finger electrode are drawn out by the leader wire, and the leader wire is fixed to the substrate.

At this time, when soldering the lead wire with a constant width b in the direction perpendicular to the finger electrode, the width c of the soldered portion of the finger electrode is preformed to be wide or a constant width c. .

Also, in the case of soldering a lead wire with a constant width (b) in a direction perpendicular to the finger electrode, the gap (a) between the width (c) of the widened portion of the finger electrode and the width (c) of the adjacent widened portion is made smaller than the length of the soldering iron tip, and the soldering iron tip is in direct contact with the insulating film to prevent deterioration of the insulating film.

In addition, the soldering is performed by ultrasonic soldering.

In addition, the ultrasonic intensity used in ultrasonic soldering is designed to have an output that is lower than the performance deterioration due to destruction of the insulating film as long as the lead wire can be soldered.

In addition, pre-soldering without ultrasonic waves or ultrasonic pre-soldering is carried out in advance on the part to which the lead wire is to be brazed by soldering.

In addition, in the case where the lead wire is pre-soldered to the soldered portion, the lead wire is soldered without ultrasonic waves.

The lead wires to be soldered by soldering are pre-soldered in advance.

In addition, solder is made to contain one or more of zinc, copper, and silver in tin or tin.

Therefore, in the present invention, a region generating high electron concentration when irradiated with light or the like is formed on the substrate, an insulating film that transmits light or the like is formed on the region, and on the insulating film, an extraction port for extracting electrons from the region In a solar cell that forms a finger electrode and draws electrons to the outside through the finger electrode and forms a circuit by introducing electrons from the back surface of the substrate, an aluminum electrode is formed on the entire surface of the back surface of the substrate or the aluminum electrode is A hole is formed in a part, and a leader wire is soldered to a part of the entire surface of the formed aluminum electrode or a hole is formed, so that electrons are introduced from the back surface of the substrate and the leader wire is fixed to the board. .

At this time, a part of the entire surface of the aluminum electrode or a part in which a hole is formed is a part corresponding to the leader line on the surface.

In addition, the soldering is performed by ultrasonic soldering.

In addition, pre-soldering without ultrasonic waves or ultrasonic pre-soldering is carried out in advance on the part to which the lead wire is to be brazed by soldering.

In addition, in the case where the lead wire is pre-soldered to the soldered portion, the lead wire is soldered without ultrasonic waves.

The lead wires to be soldered by soldering are pre-soldered in advance.

In the soldering of the lead wire, the soldering is carried out in a state in which the temperature of the portion to be soldered is preheated from the temperature at which the solder melts to room temperature or higher.

In addition, solder is made to contain one or more of zinc, copper, and silver in tin or tin.

The present invention pays attention to the fact that the upper part of the finger electrode on the surface of the silicon substrate is exposed on the insulating film as described above, and directly solders an external terminal band-shaped ribbon to the exposed upper part of the finger electrode to resist A solar cell with high efficiency and capable of firmly fixing the lead wire can be obtained by reducing the component and reducing electron leakage, and having a configuration in which the ribbon can be firmly soldered directly to the nitride film or through glass.

Moreover, the conventional silver busbar electrode becomes unnecessary, and silver usage-amount can be reduced.

Further, the conventional step of forming the silver bus bar electrode becomes unnecessary, and the number of steps can be reduced.

In addition, by directly soldering the lead wire (ribbon) to the finger electrode to reduce the resistance value, the electron extraction efficiency can be increased.

According to the present invention, as described above, by drilling a hole in the aluminum electrode or a part of the aluminum electrode on the back surface of the silicon substrate 1 and soldering it directly to the aluminum electrode or the hole in the aluminum electrode, the resistance value of the lead wire portion is reduced. In addition, it can be fixed with sufficient fixing strength.

In addition, compared to the conventional case where silver is formed by drilling a hole in an aluminum electrode on the back side and lead wires are soldered thereto, the lead wire can be firmly fixed even if the amount of silver used is reduced and the steps of silver application and sintering are reduced.

In addition, by directly soldering the lead wire (ribbon) to the aluminum electrode or the silicon substrate under the hole to reduce the resistance value, the electron inflow efficiency is increased, resulting in a high-efficiency solar cell.

1 is a block diagram of essential parts of the present invention.
Fig. 2 is an explanatory flowchart of the manufacturing method of the present invention (part 1 of the explanatory flowchart).
Fig. 3 is an explanatory flow chart (2 in the explanatory flow chart) of the manufacturing method of the present invention.
Fig. 4 is an explanatory view (surface-explanatory view 1) of the present invention.
Fig. 5 is an explanatory view (surface-explanatory view 2) of the present invention.
Fig. 6 is an explanatory view (rear side - explanatory view 1) of the present invention.
Fig. 7 is an explanatory diagram (1 in the explanatory diagram) of the present invention.
Fig. 8 is an explanatory diagram (2 in the explanatory diagram) of the present invention.
Fig. 9 is an explanatory diagram (3 in the explanatory diagram) of the present invention.
Fig. 10 is an explanatory diagram (4 in the explanatory diagram) of the present invention.
Fig. 11 is an explanatory diagram (5 in the explanatory diagram) of the present invention.
12 is an explanatory diagram of the prior art.

(Example 1)

1 shows a structural example of the main part of the present invention.

Fig. 1 (a) shows an example of the main part configuration of the so-called ABS technique-0, and Fig. 1 (a-1) shows a detailed example of the main part configuration of its front and back surfaces.

Fig. 1 (b) shows an example of the configuration of main parts of the so-called ABS technique-1, and Fig. 1 (b-1) shows a detailed example of the configuration of the main parts of the front and back surfaces.

Fig. 1(c) shows an example of the main part configuration of the so-called ABS technique-2, and Fig. 1(c-1) shows a detailed example of the main part configuration of the front and back surfaces thereof.

In Fig. 1, a silicon substrate 1 is a silicon substrate (single crystal, polycrystal) on which a solar cell is to be formed.

A nitride film (insulating film) 2 is formed on the silicon substrate 1, for example, in a high-concentration electron region (a region that generates a high-concentration electron region when irradiated with sunlight or the like from above). After formation (known), it is a thin, transparent insulating film that is firmly formed on the high-concentration electron region as a transparent (transparent that transmits sunlight, etc.) film (known).

The finger electrode 3 is a lower layer by screen-printing a paste containing silver and lead glass on the nitride film 2, drying by heating with a solvent, and sintering. A path electrically connected to the high concentration electron region is formed in the nitride film 2 of the lead glass by the firing phenomenon of lead glass, and electrons generated in the high concentration electron region from the finger electrode 3 are transferred to the nitride film (insulating film) (2) It is to withdraw in the direction above (notice).

As shown in Fig. 1(a), the bus bar electrode 4 is coated with glass of a certain width in the direction orthogonal to the finger electrode 3 and only on the portion where the finger electrode 3 is not present (塗布), heat-drying with a solvent, sintering, and firmly fixed to the nitride film (2). The bus bar electrode 4 does not have to be conductive here, and it is sufficient if it can be firmly fixed to the nitride film 2 and lead wires can be soldered (described later). For example, a non-conductive ABS paste (a glass paste of vanadium, barium, (tin or zinc, or both (or oxides thereof)) was used in this experiment.

The ribbon (lead wire) 5 is a lead wire directly soldered to the finger electrode 3 , and electrons generated in the high-concentration electron region are directly soldered to the finger electrode 3 . to be withdrawn to the outside.

The solder 6 attaches the ribbon 5 to the finger electrode 3 and the bus bar electrode 4 (Fig. 1(a)), and the nitride film 2 (Fig. 1(b), Fig. 1(c)). ) is the solder to be soldered to.

The aluminum electrode 7 is an aluminum electrode formed on the back surface of the silicon substrate 1 .

The solder 8 is, in Figs. 1 (a) and 1 (b), on the aluminum electrode 7 formed on the entire surface of the back surface of the silicon substrate 1, the ribbon 5 on the surface is soldered 6 ) to solder the ribbon 9 to the portion on the back side corresponding to the soldered portion. As for the solder 8 used in the present invention, it is preferable to add several % to tens of % of zinc to tin or tin, and add 0.0 % to tens of % of copper, silver, or the like. A ratio higher than this or other metals may be added as needed (the same hereinafter).

In addition, in Fig. 1(c), the solder 8 is applied to a portion of the hole above the aluminum electrode 7 in which a hole is formed in a part of the back surface of the silicon substrate 1 and to an aluminum portion other than the hole, The ribbon 9 is soldered to the portion on the back side corresponding to the portion where the front side ribbon 5 is soldered with the solder 6 .

The ribbon (lead wire) 9 is an aluminum electrode 7 formed on the back surface of the silicon substrate 1 with solder 8, and the holed portion of the aluminum electrode 7 is attached to the silicon substrate 1 below it. By soldering, electrons are introduced.

Hereinafter, each configuration will be described in detail with reference to FIGS. 1 (a-1), (b-1) and (c-1).

With respect to ABS technique-0 of Fig. 1 (a-1):

Surface: On the surface (the upper surface of the silicon substrate 1 in FIG. It is a glass containing vanadate as a main component, and a solderable glass) is substituted for the conventional bus bar electrode (silver). In this state, electrons generated in the high-concentration electron region of the silicon substrate 1 are drawn out by the ribbon 5 directly soldered with the solder 6 through the finger electrode 3 . For this reason, in the path of the conventional photoelectron concentration region - the finger electrode 3 - the silver bus bar electrode - the ribbon 5, the part of the silver bus bar electrode is omitted and the ribbon 5 is directly connected from the finger electrode 3 This allows electrons to flow and can be withdrawn to the outside, thereby reducing the resistance by reducing the loss, and also making it possible to prevent electron leakage from the conventional bus bar electrode.

· Back side: On the back side (the lower side of the silicon substrate 1 in FIG. The ribbon 9 is directly soldered to the portion corresponding to the (ABS paste) 4 .

With the above configuration, electrons generated in the high-concentration electron region of the silicon substrate 1 can be directly withdrawn from the surface through the finger electrode 3 - the ribbon 5, and the ribbon 5 is It becomes possible to directly and firmly solder to the silicon substrate 1 with solder 6 at a portion corresponding to the bus bar electrode (which may be non-conductive, for example, ABS paste) 4 . On the back side, it is possible to sinter the silver paste on the conventional aluminum electrode 7 and eliminate the effort of soldering the ribbon thereto, so that it is possible to directly solder the ribbon on the aluminum electrode 7 according to the present invention and firmly fix it. do.

With respect to ABS technique-1 of (b-1) of FIG. 1 :

Surface: On the surface (the upper surface of the silicon substrate 1 in FIG. It is soldered to the part with a certain width (b) (refer to FIG. 4 and the like). In this state, electrons generated in the high-concentration electron region of the silicon substrate 1 are drawn out by the ribbon 5 directly soldered with the solder 6 through the finger electrode 3, and the ribbon 5 can be firmly fixed to the silicon substrate 1 via the nitride film 2 . For this reason, in the absence of a conventional bus bar electrode, electrons are directly drawn to the outside in a path called the photoelectron concentration region - the finger electrode 3 - the ribbon 5, and the ribbon 5 is formed by the nitride film 2 It becomes possible to fix firmly to the silicon substrate 1 through this.

· Back side: Same as (a-1) of FIG. 1 .

With the above configuration, it is possible to directly withdraw electrons generated in the high-concentration electron region of the silicon substrate 1 to the outside through the finger electrode 3 - the ribbon 5 on the surface, and the ribbon 5 It becomes possible to fix firmly to the silicon substrate 1 via the nitride film 2 . On the back side, as in Fig. 1(a), the conventional silver paste is sintered on the aluminum electrode 7 and the effort of soldering the ribbon thereto is omitted, and the ribbon is directly soldered onto the aluminum electrode 7 according to the present invention. This makes it possible to firmly fix it.

With respect to ABS technique-2 of (c-1) of FIG. 1 :

·Surface: Same as (b-1) of FIG. 1 .

· Back side: On the back side (the lower side of the silicon substrate 1 in FIG. As a part other than the part of the hole, the ribbon 9 is brazed to the part of the said back surface corresponding to the part to which the ribbon 5 of the front surface was brazed. In this way, the ribbon 9 is directly soldered to the silicon substrate 1 with the solder 8 at the hole portion and can be firmly fixed to the silicon substrate 1, while also making it possible to reduce the resistance component. do.

With the above configuration, it is possible to directly withdraw electrons generated in the high-concentration electron region of the silicon substrate 1 to the outside through the finger electrode 3 - the ribbon 5 on the surface, and the ribbon 5 It becomes possible to fix firmly to the silicon substrate 1 via the nitride film 2 . On the back side, according to the present invention, the ribbon 9 can be directly soldered to the silicon substrate 1 with the solder 8 through the hole of the aluminum electrode 7 to be firmly fixed.

Next, the manufacturing method of the structure of Fig. 1 will be described in detail in accordance with the procedure of Figs.

2 and 3 show an explanatory flow chart of the manufacturing method of the present invention.

In Fig. 2, S1 prepares a substrate. This is a silicon substrate 1 on which the solar cell of Fig. 1 is to be formed, as described above, for example, a P-type single crystal or polycrystal silicon substrate 1 as described on the right is prepared.

S2 forms a nitride film. This forms a nitride film (insulating film) 2 on the surface of the silicon substrate 1 of Fig. 1 which has already been described. The thickness of the nitride film 2 is preferably about 60-90 nm, for example.

In S3, an aluminum paste is applied to the back surface. This is applied by screen printing an aluminum paste on the back surface of the silicon substrate 1 of FIG. 1 as described on the right. This application is applied to the entire surface of the back surface in Fig. 1 (a-1) and Fig. 1 (b-1). In Fig. 1 (c-1), aluminum paste is applied with or without a space on the back surface in a direction orthogonal to the pattern of the finger electrode 3 on the surface, and a band-shaped pattern on the silicon substrate 1 on the back surface. Alternatively, it is coated with scattered strip-shaped aluminum paste (the uncoated part becomes the part of the hole without the aluminum electrode 7).

S4 removes a solvent. In this case, the aluminum paste applied in S3 is heat-dried (for example, from 80°C to 120°C, heat-dried for 30 minutes to 60 minutes) to remove the solvent.

S5 prints a finger electrode on the surface. This is screen-printed on the nitride film 2 in Fig. 1 using, for example, a paste containing silver and lead glass frit described on the right.

S6 removes a solvent. In this case, the paste applied in S5 is heat-dried (for example, from 80°C to 120°C, heat-dried for 30 minutes to 60 minutes) to remove the solvent.

In Fig. 3, in the case of Fig. 1 (a), steps S7 and S8 are performed. S7 and S8 may be performed simultaneously with printing and solvent removal of the finger electrodes of S5 and S6.

S7 prints busbar electrodes. This screen-prints the busbar electrode 4 of FIG. 1 with ABS paste.

S8 performs solvent removal. These S7 and S8 use ABS paste (vanadium, barium, glass paste of tin or zinc or both (or oxides thereof)) to screen-print the busbar electrode as shown in FIG. Conduct.

S9 is sintered. In this case, the aluminum electrode 7, the finger electrode 3, and the bus bar electrode 4 on the back surface that have been printed and solvent-removed in S3 and S4, S5 and S6, and S7 and S8, and if necessary, the bus bar electrode 4 are collectively sintered. Moreover, you may sinter individually. As described on the right, for example, sintering is preferably in the range of 750 to 820°C and 1 second to 60 seconds, and is performed by irradiating infrared rays.

S10 performs ultrasonic soldering on the surface. In this case, the lead wire (ribbon 5) on the surface is directly soldered to the finger electrode 3 as described above in FIG. In addition, when the part to be soldered is previously pre-soldered (ultrasonic pre-soldering or ultrasonic-free pre-soldering) as mentioned above, ultrasonic-free soldering may be sufficient. In addition, ultrasonic soldering (soldering degree without ultrasonic wave) is soldered in a state in which the temperature of the part to be brazed (and the part to be soldered if possible) is preheated to the temperature at which the solder is dissolved (below the melting temperature, at least room temperature), It becomes possible to reliably solder the solder of the present invention (the same is true for ultrasonic soldering (soldering without ultrasonic waves) of other parts).

S11 performs ultrasonic soldering on the back surface. As described above in FIG. 1 , the lead wire (ribbon 9) is directly soldered to the aluminum electrode 7 or directly soldered to the silicon substrate 1 inside the hole of the aluminum electrode 7 . In addition, when the part to be soldered is previously pre-soldered (ultrasonic pre-soldering or ultrasonic-free pre-soldering) as mentioned above, ultrasonic-free soldering may be sufficient.

As described above, after the nitride film (insulating film) 2 is formed on the surface of the silicon substrate 1 in FIG. 1, the aluminum paste forming the aluminum electrode 7 is applied and solvent removed on the back surface, and the finger electrode ( 3) The silver/lead glass frit forming is applied and solvent removed, and if necessary, the ABS paste forming the bus bar electrode 4 is applied and solvent removed, and these aluminum electrodes 7 and finger electrodes 3 , it becomes possible to collectively sinter the bus bar electrodes 4 as needed, to form an aluminum electrode 7 on the back side, a finger electrode 3 on the front surface, and an ABS bus bar electrode 4 if necessary. Then, the ribbon 5 is directly soldered to both the surface finger electrode 3 and the exposed nitride film 2 with the solder 6 (Fig. 1 (b), Fig. 1 (c)), or the finger The ribbon 5 is directly soldered to both the electrode 3 and the bus bar electrode 4 with the solder 6 (Fig. 1 (a)), and the aluminum electrode 7 and the ribbon 5 on the back surface are further ) directly with the solder 8 (Fig. 1 (a), Fig. 1 (b)), or directly solder the ribbon 8 to the silicon substrate 1 through the hole of the aluminum electrode 7 By soldering with (8) and directly soldering the ribbon 8 with the solder 8 to the part without a hole of the aluminum electrode 7 (Fig. 1(c)), the ribbon 9 is firmly attached to the silicon substrate ( It becomes possible to reduce the resistance to the silicon substrate 1 from the fixing to 1) and the ribbon 9 .

Fig. 4 shows an explanatory view (surface-explanatory view 1) of the present invention.

Fig. 4(a) shows a pattern example of the finger electrode 3, and Fig. 4(b) shows an enlarged view of Fig. 4(a).

In Fig. 4, an example of the pattern of the finger electrodes 3 is a region in which a ribbon 5 of width b is soldered with solder 6 in a direction orthogonal to the finger electrode 3 of Fig. 1 (bus shown in the drawing). An example in which the width of the bar region 41 and the same region) is increased to the width c is shown. By increasing the width of the finger electrode 3 by this width c, it becomes possible to increase the soldering area (contact area) between the ribbon 5 and the finger electrode 3, thereby reducing the contact resistance. On the other hand, if the width c is widened too much, the leakage (recombination) of electrons from the widened portion increases and the leakage current tends to increase. Therefore, it is necessary to determine the optimum value by experiment.

In addition, when soldering in a state in which the width b of the bus bar region 41 (the width of the ribbon 5) is widened as shown in FIG. Since the gap (a) became smaller than the length of the ultrasonic soldering iron tip, it was necessary to prevent the soldering iron tip from directly contacting the nitride film 2 below and not having an effect such as destroying the nitride film 2 . For example, when the length of the soldering iron tip is 2 mm, the gap (a) is about 1 mm. As a result of the experiment, it was found that the nitride film 2 was not adversely affected.

In the case of direct soldering, tin and zinc were reliably adhered to the solder material of the nitride film 2 of the substrate, and an adhesive force of 5N or more, which was not obtained with ordinary solder materials (tin and lead), was obtained.

Fig. 5 shows an explanatory view (surface-explanatory view 2) of the present invention. This is the previously described Fig. 1 (b). An enlarged detail view of the surface of (c) is shown.

In Fig. 5, a nitride film (insulating film) 2 is formed on the surface of a silicon substrate 1, a paste of silver and lead glass is applied to the pattern of the finger electrode 3 thereon, and sintered. (3) is formed (a hole is made in the nitride film 2 to form the finger electrode 3 made of silver inside).

In the present invention, the ribbon 5 is directly soldered to the finger electrode 3 protruding above the nitride film 2 with solder 6, and the ribbon 5 is simultaneously soldered to the part of the nitride film 2 with solder 6 ) is soldered. At this time, by making the width of the finger electrode 3 wider (a portion corresponding to the width of the ribbon 5 is widened) as shown in Fig. 4 described above, the distance between the finger electrode 3 and the ribbon 5 is The contact resistance can be reduced by increasing the contact area, and the gap is made smaller than the length of the solder iron tip so that the solder iron tip does not directly contact the nitride film 2 of the substrate, thereby preventing the destruction of the nitride film 2, etc. Study so as not to cause adverse effects (refer to the description of Fig. 4).

Thereby, direct extraction of electrons from the high-concentration electron region to the ribbon 5 through the finger electrode 3, and reducing the contact resistance between the finger electrode 3 and the ribbon 5 to achieve high efficiency In addition to being possible, it becomes possible to firmly fix the ribbon 5 directly to the nitride film 2 by soldering it with the solder 6 .

Fig. 6 shows an explanatory view (rear side - explanatory view 1) of the present invention.

Fig. 6(a) shows a configuration example of the conventional back surface. Conventionally, an aluminum electrode in which a hole is partially formed is formed on the back surface of a silicon substrate, a silver paste is applied and sintered in the hole portion to form a silver electrode, and the ribbon is soldered to the silver electrode (solder solder). It was soldered and the ribbon was fixed to the silicon substrate with a force greater than the prescribed force.

Fig. 6B shows an example of direct soldering of the present invention.

Fig. 6 (b-1) shows an example in which an aluminum electrode 7 is formed on the entire surface of the back surface of the silicon substrate 1, and a ribbon 9 is soldered thereto with a solder 8 (Fig. 1). (a) Same as (b) of Fig. 1). In the present invention, the ribbon 9 can be directly ultrasonically soldered to the aluminum electrode 7 with an ultrasonic soldering iron using the solder (tin, zinc) 8 . Further, in the case of pre-soldering to the aluminum electrode 7, soldering without ultrasonic waves is possible.

Fig. 6(b-2) shows an aluminum electrode 7 having a hole formed in a part of it on the back surface of the silicon substrate 1, and a ribbon ( An example of soldering 9) is shown (same as Fig. 1(c)). In the present invention, the ribbon 9 is directly attached to the silicon substrate 1 of the hole portion of the aluminum electrode 7 and the aluminum electrode 7 other than the hole with an ultrasonic soldering iron using solder (tin, zinc) 8. can be ultrasonically soldered. In the case of preliminary soldering, soldering without ultrasonic waves is possible.

Fig. 7 shows an explanatory diagram (1 in the explanatory diagram) of the present invention. This shows an example of ultrasonic soldering conditions.

In Fig. 7, in the case of ultrasonic soldering of the ribbons 5 and 9 with the solders 6 and 8 and ultrasonic waves applied to them in Fig. 1, etc., if the output of the ultrasonic waves is too strong, the nitride film 2 of Fig. 1 When the output of the ultrasonic wave was too weak, a situation in which the ribbon 5.9 could not be soldered occurred. Ultrasonic soldering requires optimum ultrasonic output, and in particular, it depends on the size of the ultrasonic soldering part (region) of the finger electrode 3 . In this experiment, the device deteriorated (the nitride film 2 was destroyed, etc., which caused adverse effects) at the ultrasonic output of 3 W or more, and the soldering failure occurred at 0.5 W or less. In this experiment, a range of 3 W or less and 0.5 W or more was a range in which good ultrasonic soldering could be performed.

Fig. 8 shows an explanatory diagram (2 in the explanatory diagram) of the present invention. This shows comparative examples of the ABS technique-1 of FIG. 1(b), the ABS technique-2 of FIG. 1(c), and the prior art of FIG.

·ABS technique-1 (FIG. 1(b)): The ribbon 9 is soldered directly to the aluminum electrode 7 on the back side. For the surface, solder the ribbon 5 directly to the finger electrode 3 and solder the ribbon 5 directly to the nitride film 2 . Accordingly, 1. The adhesion of the back side is slightly lower than that of ABS method-2, but it is sufficient for the standard. 2. Conventional silver can be reduced. 3. Good electrical characteristics.

・ABS technique-2 (Fig. 1(c)): On the back side, the ribbon 9 is directly soldered to the silicon substrate 1 under the hole of the aluminum electrode 7, and the aluminum electrode 7 in the part other than the hole Soldered directly to. The surface is the same as ABS technique-1. Accordingly, 1. Strong adhesion of the ribbon on the back side. 2. Conventional silver can be reduced. 3. Good electrical characteristics.

Conventional technique (FIG. 12): Silver sintering on the back side of the aluminum electrode 27, soldering the ribbon 29 to it, or sintering silver in the hole of the aluminum electrode 27 to connect to the silicon substrate 21, Solder the ribbon (29) to this silver. The surface is soldered by soldering the ribbon through the finger electrode 23, the silver busbar electrode. Accordingly, 1. A silver bus bar electrode on the surface is required. 2. A silver electrode is required on the back side.

Fig. 9 shows an explanatory diagram (3 in the explanatory diagram) of the present invention.

In FIG. 9 , ABS technique-0, ABS technique-1, and ABS technique-2 correspond to ABS technique-0, ABS technique-1, and ABS technique-2 of FIG. 1 , respectively.

The crystal is a kind of polycrystalline and single crystal silicon substrate 1 .

V(v) in the electrical characteristics is an open circuit voltage of Fig. 10, which will be described later.

I (mA/cm ² ) in the electrical characteristics is a short-circuit current in FIG. 10 which will be described later.

FF in the electrical characteristics is the optimum operating point in Fig. 10, which will be described later (the point at which the maximum power is obtained).

EFF among electrical characteristics is the conversion efficiency expressed by the following (Equation 1).

EFF=Jsc×Voc×FF … … … (Formula 1)

Ref is a standard value for comparative comparison (standard value of the conventional example), here, 100 (electrical properties), 1 (adhesion force, silver), and 0 (the number of manufacturing steps).

From the experimental results shown in Fig. 9 above,

- V(V) (opening voltage) among electrical characteristics was a slightly large voltage value in all of this invention 100.7-101.7.

·Short-circuit current I is in the range of 100.0 to 101.5, and has sufficient performance compared to Ref.

The optimum operating point (FF) shows superiority in all ABS techniques compared to Ref.

· Conversion efficiency EFF shows superiority compared to Ref in ABS technique.

・The adhesion of the ribbon to the silicon substrate 1 was 2 times the standard value on the surface, and it was found to be very firmly fixed, and the back surface was also approximately the same, or directly to the silicon substrate 1 of the ABS technique-2. ), it was found to be firmly fixed by double.

- The usage-amount of the silver surface was able to reduce to half or less within the range of 0.1 to 0.5 in this invention. About the back side, this invention was able to reduce the usage-amount of silver 100%.

As for the number of manufacturing steps, the ABS technique-1 and ABS technique-2 (FIG. It became unnecessary, and the man-hours-1 and formation of the silver electrode on the back side became unnecessary, and a total of 2 steps of man-hours-1 could be reduced).

Fig. 10 shows an explanatory diagram (4 in the explanatory diagram) of the present invention. This is a diagram for easy understanding of the electrical characteristics of the solar cell of FIG. 9 described above. The horizontal axis represents the voltage drawn from the solar cell, and the vertical axis represents the current at that time.

In Fig. 10, the open circuit voltage is referred to as Voc (V in Fig. 9).

Assuming that the short-circuit current is Jsc (I in Fig. 9), the optimum operating point FF is a value at a position shown in the figure at which the product of the voltage/current characteristic curve drawn from the solar cell becomes the maximum.

The conversion efficiency is a value obtained by the formula of Jsc×Voc×FF.

Fig. 11 shows an explanatory diagram (5 in the explanatory diagram) of the present invention.

Fig. 11 (a) shows an example of a photograph of the front and back surfaces of a solar cell using ABS glass as the bus bar electrode of the ABS technique-0 of Fig. 1 (a).

Fig. 11 (a-1) shows an example of a photo of a solar cell in which the finger electrodes 3 are formed in the transverse direction of the surface and bus bar electrodes using ABS glass are formed thereon. ABS glass is formed only on the portion where there is no finger electrode 3, and on this finger electrode 3 and the portion of the bus bar electrode formed of ABS glass (non-conductive, the ribbon can be ultrasonically soldered with the solder of the present invention) Shows the photo of the soldered state of the ribbon.

Fig. 11(a-2) is the back surface of Fig. 11(a-1), and shows an example of a photograph in a state in which an aluminum electrode is formed on the entire surface.

Fig. 11(b) shows an example of a photograph of the front and back surfaces of the solar cell of ABS technique-2 of Fig. 1(c).

Fig. 11 (b-1) is a photograph of a state in which the finger electrode 3 (refer to Fig. 4) is formed by widening the width of the portion to be soldered with the finger electrode 3 in the transverse direction of the surface. shows an example of Here, the state in which the width of the finger electrode 3 in the portion to be soldered in the longitudinal direction is increased is clarified.

Fig. 11(b-2) shows an example in which an aluminum electrode 7 with holes formed in the longitudinal direction for directly soldering a ribbon to the silicon substrate 1 serving as a substrate is formed in the longitudinal direction of the back surface.

Fig. 11(b-3) shows an example of a photograph after soldering the ribbon from the top of Figs. 11(b-1) and Fig. 11(b-2).

The left side of FIG. 11(b-3) shows an example of a photograph after soldering a ribbon in the longitudinal direction to a portion of the surface of FIG. 11(b-1) where the width of the finger electrode is widened.

The right side of Fig. 11 (b-3) is a photograph after soldering the ribbon in the longitudinal direction to the aluminum-free hole (long hole) in the longitudinal direction of the aluminum electrode on the back surface of Fig. 11 (b-2). An example is shown.

1: substrate (silicon substrate)
2: nitride film (insulating film)
3: finger electrode
4: bus bar electrode
41: busbar area
5, 9: Ribbon (lead wire, leader wire)
6, 8: Solder
7: aluminum electrode

Claims (11)

When the light (光) on the substrate was irradiated (照射) high electron concentration (高電子濃度) for forming the formation region of the well to form an insulating film that transmits light on the top of the area, from the area on top of the insulating film In a solar cell which forms a finger electrode, which is an outlet for withdrawing electrons, and withdraws the electrons to the outside through the finger electrode,
In the group constant width as ping going electrode and the perpendicular direction (b) formed on the insulating film, formed by non-coating and sintering a glass paste of the non-conductive parts of the insulating film and portions in which the finger electrodes, does not have the finger-electrodes A lead wire is soldered over one non-conductive bus bar electrode with solder, electrons from the finger electrode are drawn out by the lead wire, and the lead wire is connected to the non-conductive bus bar electrode. A solar cell, characterized in that fixed to the substrate through the.
According to claim 1,
In the case of soldering a lead wire with a constant width (b) in a direction perpendicular to the finger electrode by soldering, the width (c) of the soldered portion of the finger electrode is wide or the predetermined width (c) is formed in advance. Characterized by a solar cell.
According to claim 1,
The soldering is a solar cell, characterized in that ultrasonic soldering.
3. The method of claim 2,
The soldering is a solar cell, characterized in that ultrasonic soldering.
4. The method of claim 3,
The ultrasonic strength used in the ultrasonic soldering is a solar cell, characterized in that as long as the lead wire can be soldered, and the output is smaller than that of the insulating film being destroyed and the performance deteriorated.
5. The method of claim 4,
The ultrasonic strength used in the ultrasonic soldering is a solar cell, characterized in that as long as the lead wire can be soldered, and the output is smaller than that of the insulating film being destroyed and the performance deteriorated.
7. The method according to any one of claims 1 to 6,
The lead wire is soldered by the soldering, and a portion having the finger electrode and a portion of the insulating film without the finger electrode having a constant width b in a direction perpendicular to the finger electrode formed on the insulating film are non-conductive. A solar cell characterized in that pre-soldering without ultrasonic or ultrasonic pre-soldering is carried out in advance over a non-conductive bus bar electrode formed by coating and sintering a glass paste of
7. The method according to any one of claims 1 to 6,
The lead wire is, solar cells, characterized in that the good preliminary take-soldered to the soldering by the solder.
7. The method according to any one of claims 1 to 6,
The soldering of the lead wire is a solar cell, characterized in that the soldering is carried out in a state in which the temperature of the soldered portion is pre-heated from the temperature at which the solder is melted to the room temperature or higher.
7. The method according to any one of claims 1 to 6,
The solder is a solar cell, characterized in that it contains at least one of zinc, copper, and silver in tin or tin.
A region generating a high electron concentration when irradiated with light is formed on the substrate, an insulating film that transmits light is formed on the region, and a finger electrode serving as an extraction port for withdrawing electrons from the region is formed on the insulating film, In the method of manufacturing a solar cell for withdrawing the electrons to the outside through the finger electrode,
In the group constant width as ping going electrode and the perpendicular direction (b) formed on the insulating film, formed by non-coating and sintering a glass paste of the non-conductive parts of the insulating film and portions in which the finger electrodes, does not have the finger-electrodes A lead wire is soldered over one non-conductive bus bar electrode with solder, electrons from the finger electrode are drawn out by the lead wire, and the lead wire is attached to the substrate through the non-conductive bus bar electrode. A method of manufacturing a solar cell, characterized in that fixed.

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