JPH09129906A - Integrated thin film tandem solar battery and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the fill factor (FF value). SOLUTION: A plurality of unit elements 15 are formed on a substrate 3, each of the unit elements 15 being composed of a first electrode layer 5, a first stack cell 8, a second stack cell 9 and a second electrode layer 13. The first electrode layer 5 has an insolation groove 17 which extends from the upper surface of the first electrode layer 5 to the upper surface of the substrate 3. The second electrode layer 13 is connected with the first electrode layer 5 by a connection groove 7 which extends through the second stack cell 9 and the first stack cell 8 to the upper surface or the first electrode layer 5. The first electrode layer 5 is continued to the first electrode layer 5 or the adjacent unit element 15. Thus, in an integrated thin film tandem solar battery 1 having the plurality of unit elements 15 connected in series, the first stack cell 8 is isolated by a first stack cell isolation groove 177 which extends from the upper surface or the first stack cell 8 to the upper surface of the substrate 3, in the isolation groove 17 of the first electrode layer 5.

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 the solar cell for electric power for outdoor use, the substrate size is, for example, 400 × 8.
The large area exceeds 00 (mm).

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 between the unit elements 15 adjacent to each other. By being continuous with the layer 5, the unit elements 15 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 a conductor layer on the first stack cell, after deposition of the first stack cell, taken out from the vacuum chamber and held in the atmosphere, even if performing a cleaning process, the characteristics do not deteriorate, Cost reduction of the process can be achieved.

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, as a second electrode layer 13, a metal film of Al, Ag, Cr or the like is deposited in a single film or multiple layers, and is fused by a laser scribing method in the same manner as the first electrode layer 5, 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, the continuity of the interface between the first stack cell 8 and the second stack cell 9 and the peeling of the first stack cell and the second stack cell (generation of pinholes) during cleaning after laser scribing are the causes. It turned out to be

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 portion 89 that comes into contact with the electrode constituent substance filled in the connection groove 7. In addition, the fine powder (melting residue) generated when the first electrode layer 5 is melt-cut, is generated by the first electrode layer 5 near the separation groove 17.
If it adheres to the upper part, pinholes are generated at the place where the adhered substance exists at the time of cleaning after the deposition of the first stack cell 8 and the second stack cell 9, and as a result, at the time of depositing the second electrode layer 13, the There is a problem that an unexpected short circuit occurs with the second electrode layer 13.

As described above, in the conventional integrated thin film tandem solar cell, it was impossible to realize high performance that ideally reproduces the FF value in the small area thin film solar cell.

The present invention has been made in view of the above, and an object thereof is to provide a high-performance integrated thin-film tandem solar cell with an improved FF value, and a method for manufacturing the same.

[0018]

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 located in the separation groove of the first electrode layer from the upper surface of the first stack cell to the upper surface of the substrate. Stack cell separation groove leading to Thus with separated structure.

Further, the invention of claim 2 is an integrated thin film in which a plurality of unit elements each 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 separated by a separation groove is formed on a substrate at a position to be a boundary of a power generation region, and a first stack cell is formed on the first electrode layer including the separation groove. And separating the first stack cell in the separation groove to form a first stack cell separation groove extending from the upper surface of the first stack cell to the substrate, and including the first stack cell separation groove. A second stack cell is formed on the first stack cell, the first stack cell and the second stack cell formed on the first electrode layer are separated, and the first stack cell is formed from the upper surface of the second stack cell. electrode The connection groove formed to reach the the second electrode layer is formed on the second stacked cell including the connection groove,
At least a portion of the second electrode layer is separated and a portion of the first electrode layer is not separated at a position that should be a boundary between the unit elements.

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

[0021]

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 comprises 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 3 side are connected in series on the glass substrate 3 via the first electrode layer 5. Similar to the conventional one, the first electrode layer 5 has a separation groove 17 extending from its upper surface to the upper surface of the glass substrate 3.
And the second electrode layer 13 is connected to the first electrode layer 5 through the connection groove 7 extending from the upper surface of the second stack cell 9 to the upper surface of the first electrode layer 5 through the first stack cell 8. Has been done. That is, the connection groove 7 is filled with the substance forming the second electrode layer 13, and the lower end portion thereof is in contact with the first electrode layer 5. A region including the separation groove 17 and the connection groove 7 is separated from a similar region adjacent thereto by an 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, and each unit element is separated. 15 is formed.

Here, the first stack cell 8 is separated by the separation groove 17
The feature of the integrated thin-film tandem solar cell 1 according to the present invention is that it is separated by the first stack cell separation groove 177 extending from the upper surface of the first stack cell 8 to the upper surface of the glass substrate 3. First stack cell separation groove 177
Is filled with a semiconductor that constitutes the second stack cell 9.

In the above example, the stack cells 8 and 9 are arranged such that the semiconductor layers 81 and 9 are arranged 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 first stack cell separation groove 177. Exists in the active region limited by the semiconductor of the second stack cell 9 layered as
Since it is not in contact with the second electrode layer constituent material with which the connection groove 7 is filled, the FF value higher than that of the conventional integrated thin film tandem solar cell can be 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 A transparent conductive film of SnO ₂ , ZnO, ITO or the like is deposited on a glass substrate 3 to form a first electrode layer 5, which is made to correspond to a plurality of power generation regions for integration. The first electrode layer 5 is melt-cut by the laser scribing method to form the separation groove 17. Thereby, for example, a strip-shaped power generation region is formed along one direction of the glass substrate 3. Here, in the case of a large area integrated thin film solar cell, as an example, 910 × 45
A 5 × 4 (mm) haze substrate is used, and the first electrode layer 5 is used.
The surface resistance of is set to about 10Ω.

Washing, such as washing with water, is performed to remove the fusing residue generated by laser scribing, and then plasma CVD or the like is performed over the entire surface of the first electrode layer 5 formed corresponding to the plurality of power generation regions. Thus, the semiconductor layer 81 of the first stack cell 8 is deposited. As the semiconductor layer 81 of the first stack cell 8, for example, a hydrogenated amorphous silicon layer having a p-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 of 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, but may be any of amorphous, polycrystalline or microcrystalline, and a combination thereof. Silicon carbide, silicon germanium, germanium other than silicon , Group III-V compounds, Group II-VI compounds, II
A II-VI group 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 laminate. As described above, the conductor layer 82 of the first stack cell 8 can be omitted.

Subsequently, the first stack cell 8 is melt-cut by the laser scribing method at the center of the already formed separation groove 17 of the first electrode layer 5 to form a first stack cell separation groove 177. Then, in order to remove the fusing residue generated during laser scribing, washing such as water washing is performed.

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, the nip structure from the first electrode layer side may be used, or the tandem structure itself may be used. 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, , I
II-V group compound, II-VI group compound, I-III-
Group VI compounds 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. As a specific example, 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.

Then, the first stack cell 8 and the second stack cell 9 are melt-cut by a 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 first stack cell 8
The connection groove 7 is formed to reach the upper surface of the first electrode layer 5 through the inside. Then, cleaning is performed to remove the fusing residue generated during laser scribing.

Next, by the same sputtering method or vacuum evaporation method as described above, Al, Ag, and
A metal such as Cr is 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 7 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 of which is composed of a region surrounded by and two separation grooves 19 are connected in series via the first electrode layer 5. As described above, the stack cells 8 and 9 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 applied and formed as necessary.

According to the manufacturing method of the present invention described above, the first stack cell 8 is melt-cut in the separation groove 17 on the electrode layer 5,
Since the first stack cell separation groove 17 is formed,
The highly conductive region between the first stack cell 8 and the second stack cell 9 does not come into contact with the second electrode layer in the connection groove 7, and an integrated thin film tandem solar cell having a high FF value can be obtained. Further, most of the pinholes due to the adhesion of the fusing residue of the first electrode layer 5 are generated during cleaning after scribing to form the first stack cell 8, so that the second stack cell 9 is formed thereon. As a result, a short circuit between the first electrode layer 5 and the second electrode layer 13 is prevented, and also in this respect, a higher FF value than that of the conventional integrated thin film tandem solar cell can be obtained.

MANUFACTURING EXAMPLE 2 Up to the deposition of the semiconductor layer 91 of the second stack cell 9 is performed in the same procedure as in Manufacturing 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 is formed adjacent to the already formed first electrode layer 5 and the separation groove 17 of the first stack cell 8. 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.

Next, in the same manner as in Manufacturing Example 1, at least a plurality of second electrode layers 13 are provided in the vicinity of the connection groove 7 in the region opposite to the separation groove 17 of the first electrode layer 5 with respect to the connection groove 7. The upper separation groove 19 is formed by fusion cutting by the laser scribing method corresponding to the power generation region. 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 if 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 Production Example 1 in which 3 is formed of only a 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 of a transparent conductor layer and a metal layer. In the manufacturing example 2 having a two-layer structure of ZnO as the conductor layer 92 of the second stack cell 9 and ZnO as the second electrode layer 13, for example, 50% each.
The total thickness may be 1000 angstroms by depositing 0 angstroms each.

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
Due to the problem that the output of the second stack cell 9 cannot be sufficiently taken out and the film peeling (pinhole generation) of the stack cell in the vicinity of the separation groove 17 of the first electrode layer 5,
There is a problem that the first electrode layer and the second electrode layer are easily short-circuited, but the present invention solves these problems, and F
The F value and conversion efficiency have been greatly improved. For example, AM
Comparing the FF value under the simulated sunlight of 1.5 with the conversion efficiency, the conventional product had the FF value of 0.61 to 0.68 and the conversion efficiency of 7.3 to 9.0%. In the case of invention products, F
F value is 0.68 to 0.71 and conversion efficiency is 8.8 to 10.
It was 4%, and it was confirmed that a significant improvement effect was obtained.

[0048]

EXAMPLES The details of the present invention will be described below based on specific examples.

Example 1 SnO ₂ was used as the first electrode layer 5 on the entire surface of a soda-lime glass substrate 3 having a size of 910 × 455 mm and a thickness of 4 mm, and a haze ratio of 15% and a surface resistance of 8000 Å were applied. Deposited to a film thickness. The first electrode layer 5 was fused by a laser scribing method to form a separation groove 17 corresponding to a plurality of power generation regions. As a result, a plurality of strip-shaped power generation regions were formed along one direction of the substrate 3.

Cleaning is performed to remove the fusing residue, and then a hydrogenated amorphous silicon layer having a pin structure is formed as a semiconductor layer 81 of the first stack cell layer 8 over the first electrode layer 5. It was formed by the plasma CVD method. 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, SiH ₄ and H ₂ were used as a film forming gas, the reaction pressure was set to 1.0 Torr, and i-type hydrogenated amorphous silicon was deposited to a film thickness of 700 Å by RF discharge. Further, SiH is used as a film forming gas.
₄ , using PH 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.

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 already formed
At the center of the separation groove 17 of 1., the first stack cell 8 was melt-cut by the laser scribing method to form the first stack cell separation groove 177, and cleaning was performed to remove the melting residue.

A hydrogenated amorphous silicon layer having a pin structure as a semiconductor layer 91 of the second stack cell 9 was deposited on the first stack cell 8 by the 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 , CH ₄ and H ₂ were used as film forming gases, and 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, SiH _{4 is used} as a film forming gas.
And a reaction pressure of 0.3 Torr, i-type hydrogenated amorphous silicon was deposited by RF discharge to a film thickness of 3000 angstroms. Further, S is used as a film forming gas.
Using iH ₄ , PH ₃ and H ₂ , the reaction pressure was 1.0 Torr.
As r, 20 n-type microcrystalline silicon is produced by RF discharge.
It was deposited to a film thickness of 0 Å.

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 the pseudo sunlight of 1.5, the FF value was 0.68, the conversion efficiency was 8.8, and the same operation as above was performed except that the first stack cell separation groove 177 was formed. FF of integrated thin film tandem solar cell manufactured by conventional technology
A significant improvement was seen compared with the value of 0.61 and the conversion efficiency of 7.3%.

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 was deposited by RF discharge 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 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. Next, under the same sputtering conditions, Ag was deposited to a film thickness of 2500 Å as the metal layer.

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 the pseudo sunlight of 1.5, the FF value is 0.68, the conversion efficiency is 8.8%, and the same as above except that the first stack cell separation groove 177 is formed. F of integrated thin film tandem solar cell manufactured by
A significant improvement was seen compared with an F value of 0.61 and a conversion efficiency of 7.3%.

[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. Improvements are realized.

According to the manufacturing method of claim 2, the FF
The above-mentioned claim 1 in which the value is greatly improved as compared with the conventional one.
The integrated thin film tandem solar cell of is obtained. Further, before the formation of the second stack cell, the first stack cell is melted in the separation groove on the first electrode layer to form the first stack cell separation groove. It is possible to prevent a short circuit between the first electrode layer and the second electrode layer due to peeling of the first stack cell and the second stack cell (occurrence of pinholes) due to the above, and this also allows the FF value to be the same as that of the conventional integrated thin film. It is improved compared to the tandem solar cell, and the improvement of conversion efficiency is realized.

[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 13 Second electrode layer 15 Unit element 17 Separation groove 177 First stack cell 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 in a separation groove of the first electrode layer. In the integrated thin film tandem solar cell, the first stack cell is separated by a first stack cell separation groove from the upper surface of the first stack cell to the upper surface of the substrate. 2. A first electrode layer, a first stack cell, on a substrate,
A method for manufacturing an integrated thin-film tandem solar cell in which a plurality of unit elements each including a second stack cell and a second electrode layer are connected in series, and a separation groove is formed on a substrate at a position that should be a boundary of a power generation region. Forming a first electrode layer separated by, forming a first stack cell on the first electrode layer including the separation groove, separating the first stack cell in the separation groove, the first stack A first stack cell separation groove is formed from the upper surface of the cell to the substrate, a second stack cell is formed on the first stack cell including the first stack cell separation groove, and is formed on the first electrode layer. Separated the first stack cell and the second stack cell, to form a connection groove from the upper surface of the second stack cell to the first electrode layer, a second on the second stack cell including the connection groove. Niden Forming a layer, at a position to be a unit element mutual boundary, at least the second electrode layer was separated, the manufacturing method of an integrated thin-film tandem solar cell the first electrode layer is characterized in that it does not separate.