JPH09129903A - Integrated thin film tandem solar cell and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] [Object] To provide an integrated thin-film tandem solar cell with improved FF value and prevention of reduction in short-circuit current, and a method for manufacturing the same. A plurality of unit elements including a first electrode layer, a first stack cell, a second stack cell, and a second electrode layer are formed on a substrate, and the first electrode layer is formed from the upper surface of the first electrode layer to The first electrode has a separation groove reaching the upper surface of the substrate, and the second electrode layer has a connection groove reaching the upper surface of the first electrode layer through the second stack cell and the first stack cell. An integrated thin-film tandem solar cell in which the plurality of unit elements are connected in series by connecting the plurality of unit elements in series by connecting the first electrode layer to the first electrode layer of the adjacent unit element. A structure in which one stack cell is separated by a separation groove formed so as to be continuous with the separation groove of the first electrode layer is adopted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrated thin film tandem solar cell in which a plurality of unit elements are connected and formed on a substrate and a method for manufacturing the same, and in particular, the FF value and the short circuit current value are improved and the performance is improved. And a highly reliable integrated thin-film tandem solar cell and a manufacturing method thereof.

[0002]

2. Description of the Related Art Practical applications of solar cells that directly convert sunlight energy into electric energy have been in full swing in recent years. Crystalline solar cells such as single crystal silicon and polycrystalline silicon are used as outdoor power sources. It has already been put to practical use as a solar cell. On the other hand, amorphous silicon thin-film solar cells are attracting attention as low-cost solar cells because they require few raw materials, but they are still in the development stage as a whole, and they are the power source for consumer appliances such as calculators that are already popular. Based on the track record of applications, research and development is underway to develop it into outdoor applications.

In the manufacture of thin-film solar cells, similar to the manufacture of conventional thin-film devices, deposition and patterning of thin films using the CVD method, sputtering method, etc. are repeated to build a manufacturing process for obtaining a desired structure. To do. Usually, an integrated structure in which a plurality of unit elements are connected in series and parallel on one substrate is adopted, and in a power solar cell for outdoor use, the substrate size is, for example, 400 × 800 (m
Large area exceeding m).

FIG. 2 is a sectional view showing the structure of such a conventional integrated thin film tandem solar cell. As shown in this figure, in the conventional integrated thin film tandem solar cell,
The first electrode layer 5, the first stack cell 8 composed of amorphous silicon and a conductor, the second stack cell 9 and the second electrode layer 13 having the same structure are sequentially stacked on the substrate 3, and the first stack cell 8 and The first electrode layer 5 and the second electrode layer 13 are connected via the connection groove 7 provided in the second stack cell 9, and the first electrode layer 5 is the first electrode of the unit element 15 adjacent to each other. By being continuous with the layer 5, the unit elements are connected in series.

The first electrode layer 5 is usually tin oxide (S
nO ₂ ), zinc oxide (ZnO), indium tin oxide (I
A transparent conductive film such as TO) is used, and the second electrode layer 1
As 3, a metal film of aluminum (Al), silver (Ag), chromium (Cr), or the like is used.

Such a conventional integrated thin film tandem solar cell is manufactured by the following method.
Hereinafter, description will be given based on FIG.

On the glass substrate 3, SnO ₂ , ZnO, I
A transparent conductive film such as TO is deposited as the first electrode layer 5, and for integration, the first electrode layer 5 is separated by fusion cutting by laser scribing corresponding to the power generation region (separation groove 17). Then, cleaning is performed to remove the fusing residue in the laser scribing, and the semiconductor layer 81 of the first stack cell having the pin junction structure is formed by the plasma CVD method, and the conductor layer 82 of the first stack cell is formed by the sputtering method.
Then, the semiconductor layer 91 of the second stack cell having the p-i-n junction structure is sequentially deposited over the entire surface by the plasma CVD method, and the conductor layer 92 of the second stack cell is sequentially deposited by the sputtering method.

Here, the conductor layers 82 and 92 of the stack cells 8 and 9 can be omitted, but in that case, at the interface between the first stack cell 8 and the second stack cell 9, the structure of each stack cell is formed. Since an n-p junction in the opposite direction is formed and the diode characteristic in the reverse direction of this portion may reduce the FF value and the open circuit voltage among the solar cell characteristics,
Normally, a highly conductive np interface is used at this interface. Further, by providing the conductor layer on the first stack cell, the characteristics are not deteriorated even after the first stack cell is deposited and taken out from the vacuum chamber and kept in the atmosphere or subjected to the cleaning treatment. The process cost can be reduced.

Then, in the same manner as the first electrode layer 5, the first stack cell 8 and the second stack cell 9 are melt-cut by the laser scribing method to form the connection groove 7, and then the melting residue is removed. Wash. Further, a metal film of Al, Ag, Cr or the like is deposited in a single film or a multi-layer as the second electrode layer 13, and separated in the same manner as the first electrode layer 5 by the laser scribing method, and integrated in a large area tandem. Complete the solar cell.

[0010]

However, in the above-mentioned conventional integrated thin-film solar cell, there is a phenomenon that the fill factor (FF value) of the output characteristics is low. here,
Generally, in the manufacture of integrated thin-film solar cells, optimization of individual process conditions such as the film thickness of each electrode layer 5 and 13 and the film quality of the first stack cell 8 and the second stack cell 9 is aimed at in order to improve the characteristics. To be Here, when the substrate 3 has a large area, the experiment for optimizing the individual process conditions also becomes complicated, so normally, as a preliminary experiment, a thin-film solar cell having a small area is manufactured by a simple process and its characteristics are evaluated. A method is adopted in which the optimum conditions of the individual process obtained by this are fed back to the manufacturing process of a large-area thin film solar cell.

However, even if good results are obtained in the preceding experiments, if the optimum conditions are fed back to the manufacturing process of a large area, the good results as in the preceding experiments cannot be obtained in most cases, and the solar cell characteristic Among them, the FF value and the short circuit current decrease. Therefore, in the large-area integrated thin-film tandem solar cell, the improvement of the FF value described above is an urgent and urgent task for improving the conversion efficiency.

Under these circumstances, the present inventors have made detailed investigations on the cause of this decrease in the FF value. As a result, continuity of the interface between the first stack cell 8 and the second stack cell 9, peeling of the first stack cell and the second stack cell (generation of pinholes) during cleaning after laser scribing, and the first stack It has been found that the cause is the non-uniformity of the film thickness of the semiconductor layer of the cell.

This will be described in more detail with reference to the drawings.
FIG. 3 is a cross-sectional view showing the structure of a small area thin film solar cell used in the above-mentioned preceding experiment. This small-area thin-film solar cell comprises a first electrode layer 5 made of SnO ₂ , ZnO, ITO or the like, a first stack cell 8 and a second stack cell 9 made of amorphous silicon, Al, Ag, or the like on a substrate 3. The second electrode layer 13 such as Cr is sequentially laminated, and finally the second electrode layer 13 and the periphery of the second stack cell 9 and the first stack cell 8 are obtained by patterning, and the exposed portion of the first electrode layer 5 is obtained. A measuring probe is applied to 5a and the second electrode layer 13 to measure the characteristics.

In this small-area thin-film tandem solar cell, the high conductivity portion of the interface between the first stack cell 8 and the second stack cell 9 is electrically short-circuited with the first electrode layer 5 and the second electrode layer 13. In addition, the first electrode layer 5, the first stack cell 8, the second stack cell 9 and the second electrode layer 13 are continuously formed, during which fusing by laser scribing or the like and cleaning treatment are performed. Not done.

On the other hand, in the conventional integrated thin film tandem solar cell, the high conductivity portion at the interface between the first stack cell 8 and the second stack cell 9, the first electrode layer 5 and the second electrode layer There is a contact portion connecting 13 with each other, that is, a place 89 where the electrode constituent substance filled in the connection groove 7 contacts. Further, if fine powder generated when the first electrode layer 5 is fused and adhered to the first electrode layer 5 in the vicinity of the separation groove 17, during cleaning after the deposition of the first stack cell 8 and the second stack cell 9, Pinholes are generated at the location of the deposits,
As a result, there is a problem that an unexpected short circuit occurs between the first electrode layer 5 and the second electrode layer 13 when the second electrode layer 13 is deposited.

Further, in the conventional integrated thin film tandem solar cell, since the semiconductor layer 81 of the first stack cell 8 is deposited by the plasma CVD method after the fusing of the first electrode layer 5, the nonuniformity of the in-plane potential distribution is caused. It is not relaxed by the conductivity of the first electrode layer 5, and the difference in the film thickness of the semiconductor layer 81 of the first stack cell 8 between the power generation regions on the substrate becomes large.

As described above, in the conventional integrated thin film tandem solar cell, it is impossible to obtain high performance that ideally reproduces the FF value and the short circuit current value in the small area thin film solar cell.

The present invention has been made in view of the above, and provides an integrated thin-film tandem solar cell that achieves high performance by improving the FF value and the short-circuit current value, and a method for manufacturing the same. To aim.

[0019]

In order to solve the above-mentioned problems, the invention of claim 1 is a unit comprising a first electrode layer, a first stack cell, a second stack cell and a second electrode layer on a substrate. A plurality of elements are formed, the first electrode layer has a separation groove extending from the upper surface of the first electrode layer to the upper surface of the substrate, and the second electrode layer includes the second stack cell and the first stack. Connected to the first electrode layer through a connection groove reaching the upper surface of the first electrode layer through the cell, the first electrode layer is continuous with the first electrode layer of the adjacent unit element, In the integrated thin film tandem solar cell in which the plurality of unit elements are connected in series, the first stack cell is separated by a separation groove formed so as to be continuous with the separation groove of the first electrode layer. It has a structure.

Further, the invention of claim 2 is an integrated thin film in which a plurality of unit elements including a first electrode layer, a first stack cell, a second stack cell and a second electrode layer are connected in series on a substrate. In the method for manufacturing a tandem solar cell, a first electrode layer is formed on a substrate, a first stack cell is formed on the first electrode layer, and the first electrode layer and the first stack cell are in a power generation region. Separation is performed at a place to be a boundary to form a separation groove extending from the upper surface of the first stack cell to the substrate, and a second stack cell is formed on the first stack cell including the separation groove. The first stack cell and the second stack cell formed on the electrode layer are separated to form a connection groove from the upper surface of the second stack cell to the first electrode layer, and the first stack cell including the connection groove is formed. Second on two stack cells Forming a cathode layer, at a position to be a unit element mutual boundary, at least the second electrode layer was separated, the first electrode layer is characterized in that it does not separate.

In this specification, the substrate side of the laminate is referred to as the lower side, and the side on which the lamination is performed is referred to as the upper side. In addition, dividing a layer that originally has continuity as a surface by a groove (separation groove) is called “separation”.

[0022]

1 is a sectional view showing the structure of an integrated thin film tandem solar cell 1 according to the present invention.

As shown in the figure, the integrated thin film tandem solar cell 1 includes a first electrode layer 5, a first stack cell 8, a second stack cell 9 and a second electrode layer 13 on a glass substrate 3.
A plurality of unit elements 15 provided in this order from the substrate side are connected in series on the glass substrate 3 via the first electrode layer 5. Like the conventional one, the first electrode layer 5
Are separated by a separation groove 17 extending from the upper surface thereof to the upper surface of the glass substrate 3, and the second electrode layer 13 is formed on the upper surface of the first electrode layer 5 from the upper surface of the second stack cell 9 through the first stack cell 8. It is connected to the first electrode layer 5 via the connecting groove 7 extending therethrough. That is, the connection groove 7 is filled with the substance forming the second electrode layer 13. Regions including the separation groove 17 and the connection groove 7 are separated from each other by the upper separation groove 19 extending from the upper surface of the second electrode layer 13 to the upper surface of the first electrode layer 5 to form each unit element 15. .

Here, the point that the separation groove 17 of the first electrode layer 5 extends into the first stack cell 8 to separate the first stack cell is that the integrated thin film tandem solar cell 1 according to the present invention is used.
Is a feature of. The separation groove 17 is filled with the semiconductor forming the second stack cell 9.

In the above example, each of the stack cells 8 and 9 has the semiconductor layers 81 and 9 from the first electrode side, respectively.
1 and the conductor layers 82 and 92 are laminated, but the conductor layers 82 and 92 are not essential. A transparent conductive film material is preferably used as the conductor layer, but this is not essential.

An upper isolation groove 19 that divides the laminated body into unit elements 15 separates the second electrode layer 13 and the two stack cells 8 and 9, but this is not an essential requirement either.
It is sufficient that at least the second electrode layer 13 is separated.

In the integrated thin-film tandem solar cell 1 having the above-mentioned structure, the highly conductive region between the first stack cell 8 and the second stack cell 9 is filled in the separation groove 17 to form a layer. Since it exists in the active region limited by the semiconductor of the second stack cell 9 and does not contact the second electrode layer 13 filled in the connection groove 7, the FF value higher than that of the conventional integrated thin film tandem solar cell. Is obtained.

Next, an example of a method of manufacturing the integrated thin film tandem solar cell of the present invention will be described with reference to FIG.

Production Example 1 SnO ₂ , Zn as the first electrode layer 5 on the glass substrate 3
A transparent conductive film such as O or ITO is deposited. In the case of a large area integrated thin-film solar cell, for example, 910 × 455 ×
A 4 (mm) haze substrate is used, and the surface resistance of the first electrode layer 5 is set to about 10Ω.

Then, plasma C is formed on the first electrode layer 5.
The semiconductor layer 81 of the first stack cell 8 is deposited by the VD method. The semiconductor layer 81 of the first stack cell 8 has p
A hydrogenated amorphous silicon layer having a -i-n structure is used.

This hydrogenated amorphous silicon layer is formed, for example, by the following method. First, the substrate is 10 ^-5
140 to 20 in a high vacuum chamber below Torr
At a substrate temperature of 0 ° C., silane (Si
H ₄ ), diborane (B ₂ H ₆ ), methane (CH ₄ ), hydrogen (H ₂ ) are introduced into the chamber, and the reaction pressure is about 1.0 T.
As orr, p-type hydrogenated amorphous silicon carbide is deposited to a film thickness of 50 to 200 angstrom by RF discharge. Next, silane gas and hydrogen (H ₂ ) were introduced into the chamber as a film forming gas, and the reaction pressure was set to 0.5.
The i-type hydrogenated amorphous silicon is deposited to a film thickness of about 700 Å by RF discharge at about 1.0 Torr. Further, silane, phosphine (PH ₃ ) and hydrogen (H ₂ ) were introduced into the chamber as a film forming gas, and the reaction pressure was set to about 1.0 Torr. Deposit thick.

The deposition conditions for the semiconductor layer 81 of the first stack cell 8 shown here are merely examples, and for example, the nip structure may be applied from the first electrode layer 5 side, or the tandem structure itself may be used. Good. The main material of the semiconductor layer 81 of the first stack cell 8 is not limited to hydrogenated amorphous silicon, but may be any of amorphous, polycrystalline or microcrystalline, and a combination thereof. In addition to silicon, silicon carbide, silicon germanium, Germanium, III-V group compound, II-VI group compound,
A group I-III-VI compound or the like is used, and a combination thereof may be used.

Then, the conductor layer 82 of the first stack cell 8 is deposited on the semiconductor layer 81 of the first stack cell 8 by the sputtering method. As a specific example, the substrate on which the semiconductor layer 81 of the first stack cell is deposited is put into a sputtering chamber, evacuated to a high vacuum of 1 × 10 ⁻⁶ Torr or more, and argon gas (Ar) is introduced as a sputtering gas to Z doped with aluminum oxide (Al ₂ O ₃ ) by RF discharge under a pressure of ˜5 mTorr
nO is deposited to a film thickness of 800 to 1000 angstroms. Here, as the material of the conductor layer 82 of the first stack cell 8, in addition to ZnO, a transparent conductive material such as SnO ₂ or ITO may be used, or a metal such as Al, Ag, or Cr may be used. It may be a laminated body of. As described above, the conductor layer 82 of the first stack cell 8 can be omitted.

Then, the first electrode layer 5 and the first stack cell 8 are simultaneously melt-cut by the laser scribing method so as to correspond to a plurality of power generation regions, and the separation groove 17 is formed.
Thereby, for example, a strip-shaped power generation region is formed along one direction of the substrate 3. Then, cleaning is performed to remove the fusing residue generated during laser scribing.

Then, the semiconductor layer 91 of the second stack cell 9 is formed on the entire surface of the first stack cell 8 by the plasma CVD method.
Is deposited. As the semiconductor layer 91 of the second stack cell 9, for example, a hydrogenated amorphous silicon layer having a pin structure is used. In order to form this hydrogenated amorphous silicon layer, first, the substrate is placed in a high vacuum chamber of 10 ⁻⁵ Torr or less, and silane (SiH ₄ ) and diborane (as a film forming gas) are formed at a substrate temperature of 140 to 200 ° C. B ₂ H ₆ ), methane (CH ₄ ), and hydrogen (H ₂ ) are introduced into the chamber, and the reaction pressure is set to about 1.0 Torr and RF is applied.
By discharge, p-type hydrogenated amorphous silicon carbide is deposited to a film thickness of 50 to 200 angstroms. Then, only silane gas was introduced into the chamber as a film forming gas, and the reaction pressure was set to 0.2 to 0.7 Torr by RF discharge to obtain 300 parts of i-type hydrogenated amorphous silicon.
It is deposited to a film thickness of about 0 angstrom. Further, silane, phosphine (PH ₃ ), hydrogen (H
₂ ) is introduced into the chamber, and the reaction pressure is about 1.0 Torr.
As a result of RF discharge, n-type microcrystalline silicon is removed by 100
It is deposited to a film thickness of about 200 Å.

The deposition conditions of the semiconductor layer 91 of the second stack cell 9 shown here are merely examples, and, for example, an nip structure from the first electrode layer side may be used, or a tandem structure may be used by itself. . The main material of the semiconductor layer 91 of the second stack cell 9 is not limited to hydrogenated amorphous silicon, and may be any of amorphous, polycrystalline or microcrystalline, and a combination thereof. In addition to silicon, silicon carbide, silicon germanium, germanium, , III-V compounds, II-VI compounds, I-
Group III-VI compounds and the like are also used, and these may be combined.

On the semiconductor layer 91 of the second stack cell 9, the conductor layer 92 of the second stack cell is deposited by the sputtering method. Specifically, the substrate on which the semiconductor layer 91 of the second stack cell 9 is deposited is placed in a sputtering chamber, evacuated to a high vacuum of 1 × 10 ⁻⁶ Torr or more, and argon gas (Ar) is introduced as a sputtering gas. 1 to
At a pressure of 5 mTorr, ZnO doped with aluminum oxide (Al ₂ O ₃ ) by RF discharge is added to
Deposit to a film thickness of 00 to 1000 angstroms. Here, the material of the conductor layer 92 of the second stack cell 9 is Zn
In addition to O, transparent conductive materials such as SnO ₂ and ITO, Al,
It may be a metal such as Ag or Cr, or may be a laminated body of these. As described above, the conductor layer 92 of the second stack cell 9 can be omitted.

Subsequently, the first stack cell 8 and the second stack cell 9 are simultaneously melt-cut by a laser scribing method in the vicinity of the already formed separation groove 17 of the first electrode layer 5 and the first stack cell 8, A connection groove 7 is formed from the upper surface of the second stack cell to the first electrode layer 5 through the first stack cell 8. Then, cleaning is performed to remove the fusing residue generated during laser scribing.

Next, Al and A as the second electrode layer 13 are formed by the same sputtering method or vacuum evaporation method as described above.
Metals such as g and Cr are deposited on the entire surface.

Then, in the vicinity of the connection groove 7 on the side opposite to the connection groove 7 from the separation groove 17 of the first electrode layer 5 and the first stack cell 8, the second electrode layer 13 and the second stack cell 8 are formed. 9 and the first stack cell 8 are melt-cut by a laser scribing method to form an upper separation groove 19. Thereby, the first electrode layer 5 and the second electrode layer 13 are formed on the glass substrate 3.
An integrated thin-film tandem solar cell is obtained in which a plurality of unit elements 15 each including a region surrounded by two separation grooves 19 are connected in series by the first electrode layer 5.
In addition, as described above, each stack cell may not be separated in forming the upper separation groove 19, and at least the second electrode layer 13 may be separated.

Finally, cleaning is performed to remove the fusing residue generated by laser scribing, and an appropriate passivation layer such as an epoxy resin is formed by coating if necessary.

In the above manufacturing method of the present invention, since the first electrode layer and the first stack cell are separated at the same time after the formation of the first stack cell, the fusing residue adheres on the first stack cell. It does not adhere to one electrode layer. Therefore, even if peeling (pinhole) occurs in the second stack cell, the presence of the first stack cell prevents a short circuit between the first electrode layer and the second electrode layer. The conversion efficiency is improved compared to the thin film tandem solar cell.

Further, in the present invention, since the first stack cell is formed on the continuous first electrode layer and then the unit elements are separated from each other, this occurs during plasma CVD deposition of the semiconductor layer of the first stack cell. The unevenness of the potential distribution is alleviated, the film thickness in the first stack cell is made uniform, and the reduction of the short circuit current due to the large area is suppressed, and in this respect also, the conversion efficiency is further improved.

Example 2 The steps up to the deposition of the semiconductor layer 91 of the second stack cell 9 are performed in the same procedure as in Example 1 described above. A conductor layer 92 of the second stack cell 9 is deposited on the semiconductor layer 91 of the second stack cell 9 by a sputtering method. In particular,
The substrate on which the semiconductor layer 91 of the second stack cell 9 is deposited is placed in a sputtering chamber and evacuated to a high vacuum of 1 × 10 ⁻⁶ Torr or more, and an argon gas (A
r) is introduced and RF is applied under a pressure of 1 to 5 mTorr.
ZnO doped with aluminum oxide (Al ₂ O ₃ ) is deposited by discharge to a film thickness of about 500 Å. Here, the material of the conductor layer 92 of the second stack cell 9 may be a transparent conductive material such as SnO ₂ or ITO in addition to ZnO, or may be a laminated body thereof. Further, the conductor layer 92 of the second stack cell 9 can be omitted.

Subsequently, the first stack cell 8 and the second stack cell 9 are simultaneously melt-fused by the laser scribing method, and the connection adjacent to the separation groove 17 of the already formed first electrode layer 5 and the first stack cell 8 is performed. The groove 7 is formed. Then, after cleaning is performed to remove the fusing residue generated during the laser scribing, the second electrode layer 13 made of a multilayer film is formed on the entire surface. That is, using the same sputtering method or vacuum deposition method as described above, ZnO, SnO
_2. A transparent conductor layer such as ITO and a metal layer such as Al, Ag and Cr are sequentially deposited. As a specific example, the substrate on which the conductor layer of the second stack cell is deposited is placed in a sputtering chamber, evacuated to a high vacuum of 1 × 10 ⁻⁶ Torr or more, and argon gas (Ar) is introduced as a sputtering gas to ~ 5
Al ₂ O by RF discharge under pressure of mTorr
ZnO doped with ₃ is deposited to a film thickness of about 500 Å. Next, this substrate was evacuated to a high vacuum of 1 × 10 ⁻⁶ Torr or more in a sputtering chamber, and argon gas Ar was introduced as a sputtering gas to 1
Under a pressure of ~ 5 mTorr, Ag is deposited as a metal layer to a thickness of about 3000 angstrom by RF discharge. Here, it is desirable that ZnO and Ag are continuously deposited without breaking the vacuum, but the vacuum may be broken once and deposited in another chamber or apparatus. The metal layer may have a multi-layer structure such as a laminated body of Ag and Al, and the film thickness may be 1000 angstroms or more, although it depends on the material. Further, DC sputtering may be used instead of RF sputtering.

Then, in the same manner as in Example 1, the separation groove 1 of the first electrode layer 5 and the first stack cell 8 is connected to the connection groove 7.
In the vicinity of the connection groove 7 on the side opposite to 7, at least the second electrode layer 13 is melt-cut by a laser scribing method so as to correspond to a plurality of power generation regions to form an upper separation groove 19. As a result, a plurality of unit elements 15 each including a region surrounded by the first electrode layer 5, the second electrode layer 13, and the two upper isolation trenches 19 are formed in series on the glass substrate 3.

Finally, cleaning is performed to remove the fusing residue generated by the laser scribing method, and an appropriate passivation layer such as an epoxy resin is applied and formed as necessary.

In the above, the film thickness of ZnO deposited on the semiconductor layer is 600 to 1200 angstroms,
It is preferable to set it in the range of 800 to 1000 angstroms. This is to efficiently reflect the light incident from the glass substrate 3 side on the second electrode layer 13 side to obtain the “light confinement effect”. Therefore, the second electrode layer 1
In Example 1 in which 3 is formed of only metal, ZnO is deposited to a film thickness of 800 to 1000 angstrom as the conductor layer 92 of the second stack cell 9, and the second electrode layer 13 is formed as a transparent conductor layer and a metal layer. In Production Example 2 having a two-layer structure, ZnO as the conductor layer 92 of the second stack cell 9 and ZnO as the second electrode layer 13 are, for example, 500 each.
A total of 1000 Å may be obtained by depositing each angstrom.

The integrated thin-film tandem solar cell of the present invention, which has been described in detail above, solves the problems of conventional products and realizes a significant improvement in performance. That is, in the conventional product, a region having a high conductivity between the first stack cell 8 and the second stack cell 9 connects the first electrode layer 5 and the second electrode layer 13 and is filled with a substance forming the electrode layer. Connection groove 7
The first stack cell 8 and the second stack cell 9 are in contact with each other and the output of the second stack cell 9 cannot be sufficiently taken out, or the first stack cell 8 and the second stack cell 9 are deposited after the separation of the first electrode layer 5. CV of the semiconductor layer 81 of No. 8
During the deposition by D, the problem that the film thickness distribution becomes non-uniform due to the non-uniform potential distribution in the surface, and further the first electrode layer 5
There is also a problem that the first electrode layer and the second electrode layer are easily short-circuited due to film separation (generation of pinholes) in the vicinity of the separation groove 17, but the present invention solves these problems, The FF value and conversion efficiency have been greatly improved. For example, when comparing the conversion efficiency with the FF value under artificial sunlight of AM1.5, the FF value of the conventional product was 0.61 to 0.68 and the conversion efficiency was 7.3 to 9.0%. On the other hand, the invention product has an FF value of 0.68 to 0.71 and a conversion efficiency of 8.8 to
It was 10.4%, and it was confirmed that a significant improvement effect was obtained.

[0050]

EXAMPLES Example 1 SnO ₂ as the first electrode layer 5 was coated on the entire one surface of a blue glass substrate 3 having a thickness of 910 × 455 mm and a thickness of 4 mm with a haze ratio of 15% and a surface resistance of 10 Ω to 8000 Å. Deposited to a film thickness of. The semiconductor layer 81 of the first stack cell layer 8 is formed over the entire surface of the first electrode layer 5.
As a result, a hydrogenated amorphous silicon layer having a pin structure was formed by a plasma CVD method. That is, first, in a high-vacuum chamber of 10 ⁻⁵ Torr or less, at a substrate temperature of 160 ° C., SiH ₄ , B ₂ H ₆ , C as film forming gases.
Using H ₄ and H ₂ , the reaction pressure was 1.0 Torr,
A p-type hydrogenated amorphous silicon carbide was deposited to a film thickness of 50 angstrom by RF discharge. Next, using SiH ₄ and H ₂ as film forming gases, the reaction pressure was 1.
At 0 Torr, i-type hydrogenated amorphous silicon was deposited to a film thickness of 700 Å by RF discharge. Further, SiH ₄ , PH ₃ and H _{2 are used} as a film forming gas.
N-type microcrystalline silicon was deposited to a film thickness of 200 angstroms by RF discharge with a reaction pressure of 1.0 Torr.

Then, the conductor layer 82 of the first stack cell 8 was deposited on the semiconductor layer 81 by the sputtering method. That is, in the sputtering chamber evacuated to a high vacuum of 1 × 10 ^-6 Torr or more, A was used as the sputtering gas.
ZnO doped with Al ₂ O ₃ was deposited to a thickness of 800 Å by RF discharge under a pressure of 3 mTorr using r.

Next, the first electrode layer 5 and the first stack cell 8 are fused and cut by the laser scribing method to form the separation groove 1.
7 was formed. Thereby, along one direction of the substrate 3,
A plurality of strip-shaped power generation regions were formed.

Cleaning is performed to remove the fusing residue, and a hydrogenated amorphous silicon layer having a pin structure is used as a semiconductor layer 91 of the second stack cell 9 over the entire surface of the first stack cell 8 by a plasma CVD method. Deposited by. That is, first, Si was used as a film forming gas at a substrate temperature of 160 ° C. in a high vacuum chamber of 10 ⁻⁵ Torr or less.
Using H ₄ , B ₂ H ₆ , CH ₄ and H ₂ , the reaction pressure was 1.
At 0 Torr, p-type hydrogenated amorphous silicon carbide was deposited to a film thickness of 50 Å by RF discharge. Next, using SiH ₄ as a film forming gas, the reaction pressure was set to 0.3 Torr, and i-type hydrogenated amorphous silicon was deposited to a film thickness of 3000 Å by RF discharge. Further, as a film forming gas, SiH ₄ , P
Using H ₃ and H ₂ , and setting the reaction pressure to 1.0 Torr,
N-type microcrystalline silicon was deposited to a film thickness of 200 Å by RF discharge.

The conductor layer 92 of the second stack cell 9 was deposited on the semiconductor layer 91 by the sputtering method.
That is, in a sputtering chamber evacuated to a high vacuum of 1 × 10 ⁻⁶ Torr or more, Ar was used as a sputtering gas, and a pressure of 3 mTorr was used to perform RF discharge.
ZnO doped with Al ₂ O ₃ was deposited to a film thickness of 800 Å.

Subsequently, the first stack cell 8 and the second stack cell 9 are melt-cut by the laser scribing method in the vicinity of the separation groove 17 of the first electrode layer 5 which has already been formed, and the upper surface of the second stack cell 9 is cut. To the upper surface of the first electrode layer 5, the connection groove 7 was formed, and cleaning was performed to remove the fusing residue.

Next, Ag was deposited as the second electrode layer 13 to a film thickness of 2500 Å by the same sputtering method as described above.

Then, in the vicinity of the connection groove 7 on the side opposite to the connection groove 7 from the separation groove 17 of the first electrode layer 5 and the first stack cell 8, the second electrode layer 13 and the second stack cell 8 are formed. 9 and the first stack cell 8 were melt-cut by a laser scribing method to form an upper separation groove 19, and the second electrode layer 13 was divided corresponding to a plurality of power generation regions. As a result, an integrated thin-film tandem solar cell in which a plurality of unit elements 15 were connected in series via the first electrode layer 5 and were formed was obtained.

Finally, cleaning for removing the fusing residue was performed, and a passivation layer was formed by coating with an epoxy resin.

AM of this integrated thin film tandem solar cell
Regarding the FF value and the conversion efficiency under pseudo sunlight of 1.5, the FF value was 0.68 and the conversion efficiency was 8.8, and the first electrode layer 5 and the first stack cell 8 were melted at the same time. FF value of the integrated thin film tandem solar cell according to the prior art manufactured in the same manner as described above except that the continuous separation groove 17 is formed.
1. Compared with the conversion efficiency of 7.3%, a significant improvement was observed.

Example 2 The procedure up to Example 1 was repeated until the semiconductor layer 91 of the second stack cell 9 was deposited. The conductor layer 92 of the second stack cell 9 was deposited on the semiconductor layer 91 by the sputtering method. That is, in a sputtering chamber evacuated to a high vacuum of 1 × 10 ⁻⁶ Torr or more, Ar was used as a sputtering gas, and under a pressure of 3 mTorr,
ZnO doped with Al ₂ O ₃ by RF discharge
Was deposited to a film thickness of 500 Å.

Subsequently, as in Example 1, the first stack cell 8 and the second stack cell 9 were simultaneously melt-cut by the laser scribing method to form the connection groove 7. Then, after cleaning for removing the fusing residue, a multilayer film including a ZnO layer and a metal layer was formed on the entire surface as the second electrode layer 13. That is, in a sputtering chamber evacuated to a high vacuum of 1 × 10 ⁻⁶ Torr or higher, Ar was used as a sputtering gas, and ZnO doped with Al ₂ O ₃ was 50 by RF discharge under a pressure of 3 mTorr.
It was deposited to a film thickness of 0 Å. Next, using the same sputtering conditions as the above metal layer, Ag was used.
Was deposited to a thickness of 2500 Å.

Next, in the same manner as in Example 1, the upper separation groove 1
9 was formed to obtain an integrated thin film tandem solar cell in which a plurality of unit elements 15 were connected and formed in series on the glass substrate 3.

Finally, cleaning was performed to remove the fusing residue, and a passivation layer was formed by coating with an epoxy resin.

AM of this integrated thin-film tandem solar cell
Regarding the FF value and the conversion efficiency under pseudo sunlight of 1.5, the FF value was 0.68 and the conversion efficiency was 8.8%.
FF value of the integrated thin film tandem solar cell according to the prior art manufactured in the same manner as above except that the continuous separation groove 17 is formed by fusing the first stack cell 8 and the first stack cell 8 at the same time.
1. Compared with the conversion efficiency of 7.3%, a significant improvement was observed.

[0065]

As described above, according to the present invention, the following excellent effects can be obtained.

In the integrated thin film tandem solar cell according to claim 1, a highly conductive region between the first stack cell and the second stack cell is filled in the first stack cell separation groove to form a layered structure. Since it exists in the active region limited by the semiconductor of the two-stack cell and does not contact the electrode layer in the connection groove, the FF value is significantly improved as compared with the conventional integrated thin film tandem solar cell, and the conversion efficiency is improved. Improvement can be realized.

According to the manufacturing method of the second aspect, the integrated thin film tandem solar cell of the first aspect can be obtained in which the FF value is significantly improved as compared with the conventional one.

Further, by separating the first electrode layer and the first stack cell at the same time after forming the first stack cell,
It is possible to prevent a short circuit between the first electrode layer and the second electrode layer, and also in this respect, the FF value is improved as compared with the conventional integrated thin film tandem solar cell, and the conversion efficiency is improved.

Furthermore, since the film thickness in each power generation region during the plasma CVD deposition of the semiconductor layer of the first stack cell is made uniform, a short circuit current value higher than that of the conventional integrated thin film tandem solar cell can be obtained. In terms of points, the conversion efficiency is further improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a structure of an integrated thin film tandem solar cell of the present invention.

FIG. 2 is a cross-sectional view showing a structure of a conventional integrated thin film tandem solar cell.

FIG. 3 is a cross-sectional view showing a structure of a small area thin film solar cell used for studying manufacturing process conditions of an integrated thin film tandem solar cell.

[Explanation of symbols]

 1 Integrated Thin-Film Tandem Solar Cell 3 Glass Substrate 5 First Electrode Layer 7 Connection Groove 8 First Stack Cell 81 Semiconductor Layer of First Stack Cell 8 82 Conductor Layer of First Stack Cell 8 Second Stack Cell 91 Second Semiconductor layer of stack cell 9 92 Conductor layer of second stack cell 9 Second electrode layer 15 Unit element 17 Separation groove 19 Upper separation groove

Claims (2)

[Claims] 1. A first electrode layer, a first stack cell, on a substrate,
A plurality of unit elements including a second stack cell and a second electrode layer are formed, the first electrode layer has a separation groove extending from the upper surface of the first electrode layer to the upper surface of the substrate, and the second electrode layer Is connected to the first electrode layer through a connection groove reaching the upper surface of the first electrode layer through the second stack cell and the first stack cell, the first electrode layer of the adjacent unit element An integrated thin film tandem solar cell in which the plurality of unit elements are connected in series by being continuous with a first electrode layer, wherein the first stack cell is the separation groove of the first electrode layer. An integrated thin-film tandem solar cell characterized by being separated by a separation groove formed so as to be continuous with the above. 2. A first electrode layer, a first stack cell, on a substrate,
A method for manufacturing an integrated thin-film tandem solar cell, comprising a plurality of unit elements each including a second stack cell and a second electrode layer connected in series, wherein a first electrode layer is formed on a substrate, and the first electrode is formed. A first stack cell is formed on a layer, the first electrode layer and the first stack cell are separated at a position to be a boundary of a power generation region, and separation from the upper surface of the first stack cell to the substrate is performed. Forming a groove, forming a second stack cell on the first stack cell including the separation groove, separating the first stack cell and the second stack cell formed on the first electrode layer, the A connection groove is formed from the upper surface of the second stack cell to the first electrode layer, and a second electrode layer is formed on the second stack cell including the connection groove. , At least the second A method of manufacturing an integrated thin-film tandem solar cell, wherein the electrode layer is separated and the first electrode layer is not separated.