JP2005093939A - Integrated tandem connection solar cell and manufacturing method of integrated tandem connection solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an integrated tandem connection solar cell which prevents a side leak of the solar cell and improves module efficiency, and a manufacturing method of the integrated tandem connection solar cell. <P>SOLUTION: The integrated tandem connection solar cell to be used includes a plurality of power generation cells 8 connected in series with a substrate 2. The power generation cells 8 include a first electrode layer 4 provided on the substrate 2, a first power generation layer 11 provided on the above, a second power generation layer 21 provided on the above, and a second electrode layer 6 provided on the above. The cells also include an electrode slot 31 extended to the substrate 2 from a surface of the first electrode layer 4, a first slot 34 extended to the first electrode layer 4 from a surface of the second power generation layer 21, and a second slot 36 extended to the first electrode layer 4 from a surface of the second electrode layer 6. The second electrode layer 6 is connected to the first electrode layer 4 through the first slot 34 just as connected in series with other adjoining power generation cells 8. A portion from a top of the electrode slot 31 to the first slot 34 in the first power generation layer 11 and the second power generation layer 21 has resistance higher than predetermined resistance. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an integrated tandem junction solar cell and a method for manufacturing an integrated tandem junction solar cell, and in particular, to an integrated tandem junction solar cell and an integrated tandem junction solar cell capable of improving the efficiency of the solar cell. Regarding the method.

In general, a thin film solar cell has a structure in which a semiconductor film is sandwiched between two electrodes. A transparent electrode is used on the light incident side of the two electrodes, and a metal back electrode is used on the other side. Low resistance Al or Ag is used for the back electrode. On the other hand, a transparent conductive film such as SnO2 (tin oxide), ITO (indium / tin oxide), ZnO (zinc oxide) is used for the transparent electrode. However, the transparent conductive film has an electrical resistivity of about 5 × 10 ⁻⁴ Ω · cm, which is two orders of magnitude larger than the metal film. Therefore, power loss occurs while the generated current flows through the transparent electrode. The power loss becomes more prominent as the substrate area becomes larger, and the power that can be taken out is reduced. Therefore, there is an integrated solar cell as a structure for reducing loss. In this structure, a plurality of solar cells (unit cells) made of the above-described structural film are formed on a single substrate and connected in series.

  As a semiconductor film, a single-junction solar cell using an amorphous silicon thin film having a pin configuration (using a p-type-i-type-n-type semiconductor), and an amorphous silicon thin film having a pin configuration and a crystal having a pin configuration A tandem junction solar cell having a structure in which a porous silicon thin film is laminated is generally known. Here, the crystalline silicon thin film generally contains a microcrystalline silicon phase in an amorphous silicon phase. Usually, in a solar cell using a silicon thin film, layers in the order of pin are arranged from the side on which sunlight is incident.

FIG. 10 is a cross-sectional view showing the structure of an integrated tandem junction integrated solar cell using a conventional silicon thin film.
The integrated tandem junction integrated solar cell shown in the figure is called a super straight type, and sunlight enters from the glass base 102 plate side. On the glass substrate 102, a transparent electrode film 104 as a first electrode and a first power generation layer 111 made of an amorphous silicon film are laminated in the order of a p layer 112, an i layer 114, and an n layer 116. Further, a second power generation layer 121 made of a crystalline silicon film is laminated on the p layer 122, the i layer 124, and the n layer 126 in this order. At this time, an intermediate layer 110 made of a transparent conductive film may be inserted between the first power generation layer 111 and the second power generation layer 121 in order to improve power generation efficiency. This is because light having a relatively short wavelength that has not been absorbed by the first power generation layer 111 is reflected toward the first power generation layer 111 and contributes to power generation. Further, a metal back electrode film 106 as a second electrode is laminated on the second power generation layer 121. A part of the metal back electrode film 106 of the left cell and a part of the transparent electrode film 104 of the right cell respectively extend and are connected to each other at the position of the first open groove 134. The electrode groove 131 is provided for the separation of the transparent electrode film 104, and the second groove 136 is provided for the separation of the metal back electrode film 106. It is formed by laser scribing in a direction perpendicular to the series connection direction (a direction perpendicular to the paper surface).

  As a conventional technique, Japanese Patent Application Laid-Open No. 9-129903 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2002-261308 (Patent Document 2) disclose solar cell technology. In a tandem junction integrated solar cell using a silicon thin film, a low resistance composed of a low resistance layer or a transparent conductive film (104) in the first power generation layer (111 in FIG. 10, hereinafter the same in the section of the prior art). The intermediate layer is in contact with the metal back electrode film (106) of the second electrode material at the side wall of the first groove (connection groove) (134). For this reason, it has been pointed out that current leakage occurs from the first power generation layer (111) of the left cell and module efficiency decreases. That is, normally, electrons should flow from the first power generation layer (111) to the second power generation layer (121), but the presence of the low resistance layer causes a partial current path bypass. In order to cope with this, Japanese Patent Application Laid-Open No. 9-129903 describes that the transparent electrode film (104) and the first power generation layer (111) are simultaneously separated when the electrode groove (131) is formed. Japanese Patent Application Laid-Open No. 2002-261308 describes that a groove for separating the first power generation layer (111) and the intermediate layer (110) at the same time is provided.

  However, even if a module was produced by a method of providing an electrode groove (131) for simultaneously separating the transparent electrode film (104) and the first power generation layer (111), the improvement in module efficiency was insufficient. This is because the low-resistance microcrystalline film is used for the p layer (122) of the second power generation layer (121) as well as the n layer (126) of the first power generation layer (111). This is because a side leak has occurred due to the p layer (122) of (121). A technique for preventing side leakage is desired. There is a need for a technology that can improve module efficiency. There is a demand for a technique that can prevent side leakage and improve module efficiency at a low cost with few process changes.

Japanese Patent Laid-Open No. 9-129903 JP 2002-261308 A

  Accordingly, an object of the present invention is to provide an integrated tandem junction solar cell and a method for manufacturing the integrated tandem junction solar cell that can prevent side leakage of the solar cell.

  Another object of the present invention is to provide an integrated tandem junction solar cell and a method for manufacturing the integrated tandem junction solar cell that can improve module efficiency.

  Still another object of the present invention is to provide an integrated tandem junction solar cell and a method for manufacturing the integrated tandem junction solar cell that can reduce side leakage and improve module efficiency at a low cost with few process changes. It is to provide.

  Hereinafter, means for solving the problem will be described using the numbers and symbols used in the best mode for carrying out the invention. These numbers and symbols are added in parentheses in order to clarify the correspondence between the description of the claims and the best mode for carrying out the invention. However, these numbers and symbols should not be used for interpreting the technical scope of the invention described in the claims.

  Therefore, in order to solve the above problems, an integrated tandem junction solar cell of the present invention includes a substrate (2) and a plurality of power generation cells (8) provided on the substrate (2) and connected in series to each other. It comprises. Each of the plurality of power generation cells (8) includes a first electrode layer (4) provided on the substrate (2) and a first power generation layer (11) provided on the first electrode layer (4) and generating power by light. ), A second power generation layer (21) provided on the first power generation layer (11) and generating power by light, and a second electrode layer (6) provided on the second power generation layer (21). Furthermore, an electrode groove (31) extending from the surface of the first electrode layer (4) to the substrate (2), and a first groove (34) extending from the surface of the second power generation layer (21) to the first electrode layer (4). And a second groove (36) extending from the surface of the second electrode layer (6) to the first electrode layer (4). The second groove (36) is separated from the electrode groove (31) on the same side as the first groove (34) than the first groove (34). Connected to the first electrode layer (4) via the first groove (34) so that the second electrode layer (6) is connected in series to the other adjacent one of the plurality of power generation cells (8). Has been. The portion from the electrode groove (31) to the first groove (34) in the first power generation layer (11) and the second power generation layer (21) has a resistance value equal to or higher than a predetermined resistance value.

  In the integrated tandem junction solar cell, the predetermined resistance value is a lateral direction from the first power generation layer (11) and the second power generation layer (21) toward the second electrode layer (6) of the first groove (34). When the directional current flows, the voltage drop from the first power generation layer (11) and the second power generation layer (21) to the first groove (34) is equal to or higher than the open circuit voltage of the second power generation layer (21). Is set.

  In the integrated tandem junction solar cell, each of the plurality of power generation cells (8) includes an end portion of each of the first power generation layer (11) and the second power generation layer (21) and the first groove (34). A high resistance portion (5, 5a) provided between the second electrode layer (6) and the second electrode layer (6) is further provided. The portion from the electrode groove (31) to the first groove (34) in the first power generation layer (11) and the second power generation layer (21) including the high resistance portion (5) is the predetermined resistance. Has a resistance value greater than or equal to the value.

  In the integrated tandem junction solar cell, the first power generation layer (11) is provided on the first semiconductor layer (12) provided on the first electrode layer (4) and on the first semiconductor layer (12). And a third semiconductor layer (16) provided on the second semiconductor layer (14). The second power generation layer (21) includes a fourth semiconductor layer (22) provided on the first power generation layer (11), and a fifth semiconductor layer (24) provided on the fourth semiconductor layer (22). And a sixth semiconductor layer (26) provided on the fifth semiconductor layer (24). The third semiconductor layer (16) has a lower resistance than the first semiconductor layer (12) and the second semiconductor layer (14). The fourth semiconductor layer (22) has a lower resistance than the fifth semiconductor layer (24). Of the third semiconductor (16) and the fourth semiconductor layer (22), the resistivity of the portion from the vicinity of the electrode groove (31) to the first groove (34) is higher than the resistivity of the other portions.

  In the integrated tandem junction solar cell, the first power generation layer (11) is provided on the first semiconductor layer (12) provided on the first electrode layer (4) and on the first semiconductor layer (12). And a third semiconductor layer (16) provided on the second semiconductor layer (14). The second power generation layer (21) includes a fourth semiconductor layer (22) provided on the first power generation layer (11), and a fifth semiconductor layer (24) provided on the fourth semiconductor layer (22). And a sixth semiconductor layer (26) provided on the fifth semiconductor layer (24). The third semiconductor layer (16) has a lower resistance than the first semiconductor layer (12) and the second semiconductor layer (14). The fourth semiconductor layer (22) has a lower resistance than the fifth semiconductor layer (24). Of the third semiconductor (16) and the fourth semiconductor (22), the portion from the vicinity of the electrode groove (31) to the first groove (34) is removed.

  In the integrated tandem junction solar cell, the first power generation layer (11) includes a conductive intermediate layer (10) provided on the side in contact with the second power generation layer (21).

  In the integrated tandem junction solar cell, the first semiconductor layer (12) is a low-resistance layer having one of the p-type and n-type conductivity types.

  In the integrated tandem junction solar cell, the first semiconductor layer (12) includes microcrystalline silicon.

  In the integrated tandem junction solar cell, the second semiconductor layer (14) and the fifth semiconductor layer (24) are intrinsic layers. The third semiconductor layer (16) is a layer having a conductivity type different from that of the first semiconductor layer (12) of the p-type and the n-type. The fourth semiconductor layer (22) is a low-resistance layer having one of the p-type and n-type conductivity types. The sixth semiconductor layer (26) is a layer having a different conductivity type from the fourth semiconductor layer (22) of the p-type and n-type.

  In order to solve the above problems, the method for producing an integrated tandem junction solar cell of the present invention includes steps (a) to (f). In the step (a), an electrode groove (31) extending from the surface of the first electrode layer (4) provided on the substrate (2) to the substrate (2) is formed. In the step (b), the first power generation layer (11) that generates power by light and the second power generation layer (21) that generates power by light are stacked in this order on the first electrode layer (4). Step (c) forms a first groove (34) extending from the surface of the second power generation layer (21) to the first electrode layer (4). In step (d), a high resistance portion having a resistance value higher than a predetermined resistance value is formed on the side surfaces of the first power generation layer (11) and the second power generation layer (21) on the first groove (34) side. In step (e), the second electrode layer (6) is formed on the second electrode layer (6) and the first groove (34). Step (f) forms a second groove (36) extending from the surface of the second electrode layer (6) to the first electrode layer (11). The second groove (36) is separated from the electrode groove (31) on the same side as the first groove (34) than the first groove (34). The second electrode layer (6) is connected to the first groove (34) so that the second power generation layer (21) is connected in series to another adjacent first power generation layer (4) separated by the second groove (36). ) Through the first electrode layer (4).

  In the manufacturing method of the integrated tandem junction solar cell, (d) step includes (d1) end portions on the first power generation layer (11) side and the second power generation layer (21) side in the first groove (34), A step of forming a high resistance portion by physical or chemical alteration.

  In the method for manufacturing an integrated tandem junction solar cell, (d) step includes (d2) a step of burying an insulator (5a ′) in the first groove (34), and (d3) an insulator (5a ′). Forming an additional first groove (34) extending from the surface of the first electrode layer (4) to the first electrode layer (4). An insulator (5a) is provided on the side surface of the first power generation layer (11) and the second power generation layer (21) on the side of the additional first groove (34).

  In order to solve the above problems, the method for producing an integrated tandem junction solar cell of the present invention includes steps (g) to (m). The step (g) forms an electrode groove (31) extending from the surface of the first electrode layer (4) provided on the substrate (2) to the substrate (2). The step (h) includes a step of forming the first semiconductor layer (12), the second semiconductor layer (14), and the third semiconductor layer (16) of the first power generation layer (11) that generates power by light on the first electrode layer (4). ) And the fourth semiconductor layer (22) of the second power generation layer (21) that generates power by light are stacked in this order. (I) The step increases the resistance values of the third semiconductor layer (16) and the fourth semiconductor layer (22) from the electrode groove (31) to a predetermined position. In the step (j), the fifth semiconductor layer (24) and the sixth semiconductor layer (26) of the second power generation layer (21) are stacked in this order on the fourth semiconductor layer (22). The step (k) forms a first groove (34) extending from the surface of the sixth semiconductor layer (26) to the first electrode layer (4). In the (l) step, the second electrode layer (6) is formed on the sixth semiconductor layer (26) and the first groove (34). Step (m) forms a second groove (36) extending from the surface of the second electrode layer (6) to the first electrode layer (4). The third semiconductor layer (16) has a lower resistance than the first semiconductor layer (12) and the second semiconductor layer (14). The fourth semiconductor layer (22) has a lower resistance than the fifth semiconductor layer (24). The second groove (36) is separated from the electrode groove (31) on the same side as the first groove (34) than the first groove (34). The second electrode layer (6) has a first groove (34) such that the second power generation layer (21) is connected in series to another adjacent first power generation layer (11) separated by the third groove (36). ) Through the first electrode layer (4). The predetermined position is between the position where the first groove (34) is formed and the second groove (36).

  In order to solve the above problems, the method for producing an integrated tandem junction solar cell of the present invention includes steps (n) to (t). In the (n) step, an electrode groove (31) extending from the surface of the first electrode layer (4) provided on the substrate (2) to the substrate (2) is formed. (O) The step comprises: on the first electrode layer (4), the first semiconductor layer (12), the second semiconductor layer (14), and the third semiconductor layer (16) of the first power generation layer (11) that generates power by light. ) And the fourth semiconductor layer (22) of the second power generation layer (21) that generates power by light are stacked in this order. In the (p) step, the third semiconductor layer (16) and the fourth semiconductor layer (22) from the electrode groove (31) to a predetermined position are removed. In the step (q), the fifth semiconductor layer (24) and the sixth semiconductor layer (26) of the second power generation layer (21) are formed on the fourth semiconductor layer (22) and the second semiconductor layer (14). The layers are stacked in this order. Step (r) forms a first groove (34) extending from the surface of the sixth semiconductor layer (26) to the first electrode layer (4). In the (s) step, the second electrode layer (6) is formed on the sixth semiconductor layer (26) and the first groove (34). Step (t) forms a second groove (36) extending from the surface of the second electrode layer (6) to the first electrode layer (4). The third semiconductor layer (16) has a lower resistance than the first semiconductor layer (12) and the second semiconductor layer (14). The fourth semiconductor layer (22) has a lower resistance than the fifth semiconductor layer (24). The second groove (36) is separated from the electrode groove (31) on the same side as the first groove (34) than the first groove (34). The second electrode layer (6) has a first groove (34) such that the second power generation layer (21) is connected in series to another adjacent first power generation layer (11) separated by the third groove (36). ) Through the first electrode layer (4). The predetermined position is between the position where the first groove (34) is formed and the second groove (36).

  In order to solve the above problems, the method for producing an integrated tandem junction solar cell of the present invention includes steps (u) to (y). In the step (u), an electrode groove (31) extending from the surface of the first electrode layer (4) provided on the substrate (2) to the substrate (2) is formed. (V) The step comprises: forming a first semiconductor layer (12), a second semiconductor layer (14), and a third semiconductor layer (16) of the first power generation layer (11) that generates power by light on the first electrode layer (4). ) And the fourth semiconductor layer (22), the fifth semiconductor layer (24), and the sixth semiconductor layer (26) of the second power generation layer (21) that generate power by light are stacked in this order. The step (w) forms a first groove (34) extending from the surface of the sixth semiconductor layer (26) to the first electrode layer (4). In the (x) step, the second electrode layer (6) is formed on the sixth semiconductor layer (26) and the first groove (34). The step (y) forms a second groove (36) extending from the surface of the second electrode layer (6) to the first electrode layer (4). The third semiconductor layer (16) has approximately the same resistance as the first semiconductor layer (12) and the second semiconductor layer (14). The fourth semiconductor layer (22) has a resistance comparable to that of the fifth semiconductor layer (24). The second groove (36) is separated from the electrode groove (31) on the same side as the first groove (34) than the first groove (34). The second electrode layer (6) has a first groove (34) such that the second power generation layer (21) is connected in series to another adjacent first power generation layer (11) separated by the second groove (36). ) Through the first electrode layer (4).

  In the method for manufacturing an integrated tandem junction solar cell, the first semiconductor layer (12) is a low-resistance layer having one of a p-type conductivity and an n-type conductivity. The second semiconductor layer (14) is an intrinsic type layer. The third semiconductor layer (16) is a layer having a conductivity type different from that of the first semiconductor layer (12) of the p-type and the n-type.

  In the method for manufacturing the integrated tandem junction solar cell, the fourth semiconductor layer (22) is a low-resistance layer having one of the p-type and n-type conductivity types. The fifth semiconductor layer (24) is a layer having an intrinsic type. The sixth semiconductor layer (26) is a layer having a different conductivity type from the fourth semiconductor layer (22) of the p-type and n-type.

  According to the present invention, side leakage of a solar cell can be prevented and module efficiency can be improved.

  Hereinafter, an embodiment of an integrated tandem junction solar cell and an integrated tandem junction solar cell manufacturing method of the present invention will be described with reference to the accompanying drawings.

(First embodiment)
First, the configuration of the first embodiment of the integrated tandem junction solar cell of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a configuration of a first embodiment of an integrated tandem junction solar cell of the present invention. The integrated tandem junction solar cell includes a substrate 2 and a plurality of power generation cells 8.

  The board | substrate 2 has translucency like glass. Each of the plurality of power generation cells 8-i (i = 1 to n, n is a natural number and the number of power generation cells) is provided on the substrate 2, and is electrically connected in series with each other. The first electrode layer 4, the first power generation layer 11, the second power generation layer 21, the current blocking unit 5, and the second electrode layer 6 are provided.

The first electrode layer 4 is provided so as to cover the substrate 2. It is a transparent conductive film formed by a film forming method such as a thermal CVD (Chemical Vapor Deposition) method or a sputtering method. Examples of the transparent conductive film include SnO ₂ (tin oxide), ITO (indium tin oxide), and ZnO (zinc oxide). In the present embodiment, it is SnO ₂ having a thickness of 0.3 to 1 μm.

  The first power generation layer 11 is provided on the first electrode layer 4, and generates power using the light transmitted through the substrate 2 and the first electrode layer 4. An amorphous silicon thin film including the p layer 12, the i layer 14, and the n layer 16 and the intermediate layer 10 are provided from the side on which sunlight is incident.

The p layer 12 is provided on the first electrode layer 4. It is a p-type amorphous semiconductor film formed by a film forming method such as PCVD (plasma enhanced CVD). In this embodiment mode, p-type a-SiC (silicon carbide) having a thickness of 5 to 20 nm is used as the p-type amorphous semiconductor film.
The i layer 14 is provided on the p layer 12. It is an i-type amorphous semiconductor film formed by a film forming method such as PCVD. In this embodiment mode, i-type a-Si (silicon) having a thickness of 150 to 400 nm is used as the i-type amorphous semiconductor film.
The n layer 16 is provided on the i layer 14. It is an n-type microcrystalline semiconductor film formed by a film forming method such as a PCVD method. In this embodiment, n-type μc-Si and a film thickness of 15 to 100 nm are used as the n-type microcrystalline semiconductor film. The conductivity of the n layer 16 is lower than the conductivity of the p layer 12 and the i layer 14.

The intermediate layer 10 is provided so as to cover the n layer 16 of the first power generation layer 11. It is a transparent conductive film formed by a film forming method such as a thermal CVD method or a sputtering method. Examples of the transparent conductive film include SnO ₂ (tin oxide), ITO (indium tin oxide), and ZnO (zinc oxide). In this embodiment, it is ZnO having a thickness of 30 to 200 nm.

  The intermediate layer 10 reflects light that is transmitted without being absorbed in the p layer 12, i layer 14, and n layer 16 of the first power generation layer 11 toward the p layer 12, i layer 14, and n layer 16. The p layer 12, i layer 14 and n layer 16 again absorb the light and contribute to power generation. Amorphous silicon is easily photodegraded, and the greater the film thickness, the greater the degradation. By providing the intermediate layer 10, the amount of current generation increases due to reflection, so that the film thickness of the amorphous silicon can be reduced accordingly. Thereby, photodegradation of amorphous silicon can be suppressed. Further, when there is no intermediate layer 10, the n layer 16 of the first power generation layer 11 and the p layer 22 of the second power generation layer 21 are joined. In that case, since a reverse potential is generated by the np junction, the generated voltage slightly decreases. By sandwiching the intermediate layer 10 having high conductivity, generation of a reverse potential at the junction can be suppressed.

  The second power generation layer 21 is provided on the first power generation layer 11, and generates power using the light transmitted through the substrate 2, the first electrode layer 4, and the first power generation layer 11. It is a crystalline silicon thin film comprising a p-layer 22, an i-layer 24, and an n-layer 26 from the side where sunlight enters.

The p layer 22 as the first semiconductor layer is provided on the first power generation layer 11. It is a p-type microcrystalline semiconductor film formed by a film forming method such as a PCVD method. In this embodiment mode, p-type μc-Si having a thickness of 5 to 50 nm is used as the p-type microcrystalline semiconductor film. The conductivity of the p layer 22 is lower than the conductivity of the i layer 24.
The i layer 24 as the second semiconductor layer covers the surface of the p layer 22 and covers (or fills) the inner surfaces of the first groove 32 (described later) and the electrode groove 31 (described later). Is provided. It is an i-type microcrystalline semiconductor film formed by a film forming method such as a PCVD method. In this embodiment mode, i-type μc-Si and a film thickness of 1 to 5 μm are used as the i-type microcrystalline semiconductor film.
The n layer 26 as the third semiconductor layer is provided on the i layer 24. It is an n-type microcrystalline semiconductor film formed by a film forming method such as a PCVD method. In this embodiment, n-type μc-Si and a film thickness of 15 to 100 nm are used as the n-type microcrystalline semiconductor film.

The 2nd electrode layer 6 is provided so that the surface of the 2nd electric power generation layer 21 may be covered, and the inner surface of the 1st open groove 34 (after-mentioned) may be covered (or an inner surface is filled up). The conductive film is formed by a film forming method such as a thermal CVD method or a sputtering method. As the conductive film connected to the first electrode layer through the second groove so that the second electrode layer 6 is connected in series to another adjacent power generation cell 8, SnO ₂ (tin oxide), Examples thereof include a transparent conductive film such as ITO (indium tin oxide) and ZnO (zinc oxide), a metal film such as Ag (silver) and Al (aluminum), or a combination thereof. In the present embodiment, ZnO having a thickness of 50 to 150 nm and Ag having a thickness of 0.2 to 0.4 μm are used.

  Each layer is provided with an electrode groove 31, a first groove 34, and a second groove 36 as described below. Each open groove is formed by laser scribing in a direction perpendicular to the series connection direction of the power generation cells 8 (a direction perpendicular to the drawing).

An electrode opening groove 31 as an electrode groove extends from the surface of the first electrode layer 4 to the substrate 2 and penetrates through the first electrode layer 4. About the 1st electrode layer 4, the adjacent electric power generation cells 8 are isolate | separated.
The first open groove 34 as the first groove extends from the surface of the second power generation layer 21 to the first electrode layer 4 and penetrates the second power generation layer 21 and the first power generation layer 11. The first groove 34 is on the side of another power generation cell 8-i + 1 adjacent to the electrode groove 31. The second electrode layer 6 is used to connect to the first electrode layer 4 of another adjacent power generation cell 8-i + 1.
The second open groove 36 as the second groove extends from the surface of the second electrode layer 6 to the first electrode layer, and penetrates the second electrode layer 6, the second power generation layer 21, and the first power generation layer 11. The second open groove 36 is provided on the same side as the first open groove 34 with respect to the electrode open groove 31, and is separated from the first open groove 34. Adjacent power generation cells 8-i and power generation cells 8-i + 1 are separated.

  The current blocking portion 5 extends from the surface of the second power generation layer so as to reach the first electrode layer 4 so as to be in contact with the end of the first power generation layer 11 and the second power generation layer 21 on the first open groove 34 side. Yes. The first power generation layer 11 and the second power generation layer 21 are provided between the end portion on the first groove 34 side and the second electrode layer 6 of the first groove 34. It has a resistivity (or resistance higher than a preset value) higher than a preset value. For example, the current blocking unit 5 may be configured such that the first power generation layer 11 and the second power generation layer 21 are formed at the end of the first groove 34 by a physical method such as laser, electron beam, ion irradiation, or chemicals such as chemicals. Examples are insulators oxidized by the method (example: silicon oxide film). The width is, for example, 10 μm.

  The resistance value of the current blocking unit 5 is set as follows. That is, the magnitude of this resistance is such that the voltage drop due to the resistance of the current blocking unit 5 when the lateral leakage current from the first power generation layer 11 and the second power generation layer 21 flows is the open circuit voltage of the second power generation layer 21. It is set to be more than about. This is because the lateral leakage current is so small that it cannot be ignored or no longer flows. In the case of the power generation cell 8 as in this embodiment, the lateral resistance is preferably 10Ω or more. More preferably, it is 1000Ω.

  The current blocking unit 5 causes current to run laterally in the low resistance layer (the low resistance layer of the first power generation layer 11 and the p layer 12 of the second power generation layer 21) (current leakage in a direction parallel to the surface of the substrate). Thus, reaching the second electrode layer 6 can be prevented.

Next, the operation of the first embodiment of the integrated tandem junction solar cell of the present invention will be described.
Referring to FIG. 1, in a single power generation cell 8-i, hole-electron pairs are generated in the first power generation layer 11 and the second power generation layer 21 by light incident from the substrate 2 side. The holes go to the first electrode layer 4 and the electrons go to the second electrode layer 6 side. These are extracted to the outside as electric power. The integrated tandem junction solar cell has a structure in which a plurality of single power generation cells 8 are connected in series. That is, the second electrode layer 6 of a certain power generation cell 8 is connected to the first electrode layer 4 of another adjacent power generation cell 8. The number of power generation cells 8 to be connected in series is set according to a desired voltage.

  The integrated tandem junction solar cell of the present invention is configured to block current between the end of the first power generation layer 11 and the second power generation layer 21 on the first groove 34 side and the second electrode layer 6 of the first groove 34. Part 5. For this reason, it is possible to block the lateral current flow in the low resistance layer (n layer 16) of the first power generation layer 11 and the p layer 22 of the second power generation layer 21. Thereby, the short circuit current Isc and the fill factor FF in the power generation cell 8 are improved. And the efficiency of the power generation cell 8 is improved, and thereby the module efficiency of the integrated tandem junction solar cell can be improved.

  Next, a first embodiment of a method for manufacturing an integrated tandem junction solar cell of the present invention will be described with reference to the accompanying drawings. 2, 3 and 1 are cross-sectional views showing an embodiment of the first method for producing an integrated tandem junction solar cell of the present invention.

As shown in FIG. 2A, SnO ₂ having a film thickness of 0.5 μm as the first electrode layer 4 is formed on the substrate 2 so as to cover the substrate ₂ by a thermal CVD method.

  In the state of FIG. 2A, a laser is irradiated from the substrate 2 side in the atmosphere using a YAG laser or YVO4 laser having a wavelength of 532 nm (second harmonic) or a wavelength of 1064 nm (fundamental wave). Thereby, an electrode open groove 31 is formed in the first electrode layer 4. The electrode open groove 31 passes through the first electrode layer 4. This state is shown in FIG. Laser irradiation may be performed from the first electrode layer 4 side.

  Subsequently, p-type a-SiC / i-type a-Si as the p-layer 12 / i-layer 14 / n-layer 16 of the first power generation layer 11 so as to cover the first electrode layer 4 and the electrode groove 31. / N-type μc-Si is laminated in this order by the PCVD method. The thickness of each film is 10 nm / 200 nm / 50 nm, respectively. Next, ZnO as the intermediate layer 10 is formed by sputtering so as to cover the n-type μc-Si. The film thickness is 100 nm. Then, the p-type μc-Si / i-type μc-Si / n-type μc-Si as the p layer 22 / i layer 24 / n layer 26 of the second power generation layer 21 are covered in this order so as to cover the first power generation layer 11. Laminate by PCVD method. The thickness of each film is 30 nm / 2 μm / 50 nm, respectively. This state is shown in FIG.

  Next, the laser is irradiated from the substrate 2 side in the atmosphere using a YAG laser or YVO4 laser having a wavelength of 532 nm. Thereby, a first groove 34 is formed in the laminated film of the first power generation layer 11 and the second power generation layer 21. The first open groove 34 penetrates the second power generation layer 21 and the first power generation layer 11. The first groove 34 is on the side of another power generation cell 8-i + 1 adjacent to the electrode groove 31. Laser irradiation may be performed from the second power generation layer 21 side. This state is shown in FIG.

Subsequently, the current blocking portion 5 is formed at the end of the first power generation layer 11 and the second power generation layer 21 on the first groove 34 side using at least one of the following methods.
(1) In the atmosphere where oxygen exists (example: in the air), the end portion is irradiated with laser light. As a result, the end portions of the first power generation layer 11 and the second power generation layer 21 are altered (oxidized) to become high resistance.
(2) The electron beam is irradiated to the end portion in an atmosphere containing oxygen, nitrogen, or carbon. As a result, the ends of the first power generation layer 11 and the second power generation layer 21 are altered (oxidized, nitrided, carbonized) to have high resistance. At this time, it is preferable that the irradiation region avoids the exposed portion of the first electrode layer 4. This is because the original function of the first electrode layer 4 is impaired.
(3) Irradiating oxygen ions, nitrogen ions or carbon ions to the end portion. As a result, the ends of the first power generation layer 11 and the second power generation layer 21 are altered (oxidized, nitrided, carbonized) to have high resistance. At this time, it is preferable that the irradiation region avoids the exposed portion of the first electrode layer 4. This is because the original function of the first electrode layer 4 is impaired.
(4) A wire discharge is generated in the vicinity of the end portion in an atmosphere in which oxygen exists (example: in the air). As a result, the end portions of the first power generation layer 11 and the second power generation layer 21 are altered (oxidized) to become high resistance.

However, the formation of the first groove 34 and the formation of the current blocking portion 5 may be performed simultaneously. In that case, at least one of the following methods can be used.
(5) The 1st groove 34 is formed using the heated jig | tool (example: grindstone, cutting tool). At that time, the surface of the end portion is strongly oxidized and becomes high resistance.
(6) The first groove 34 is formed by wire discharge. At that time, by using a gas containing oxygen gas or nitrogen gas, the surface of the end portion is altered (oxidized, nitrided, carbonized) to have high resistance.
(7) The first groove 34 is formed with a chemical. At that time, by using an oxidizing agent (for example, hydrogen peroxide solution), the surface of the end is oxidized and becomes high resistance.
(8) The first groove 34 is formed using an energy beam (eg, laser). At that time, by adjusting the energy density profile, the surface of the end portion is melted and denatured to become high resistance.

  In the state of FIG. 3B, the second electrode layer 6 is formed so as to cover the surfaces of the second power generation layer 21 and the current blocking layer 5 and cover the inner surface of the first open groove 34 (or fill the inner surface). A ZnO / Ag laminated film is formed in this order by sputtering. The thickness of each film is 100 nm / 0.3 μm. Thereby, in the 1st open groove 34, the 2nd electrode layer 6 and the 1st electrode layer 4 of other adjacent electric power generation cell 8-i + 1 are electrically connected. This state is shown in FIG.

  In the state of FIG. 3C, the laser is irradiated from the substrate 2 side in the atmosphere using a YAG laser or YVO4 laser having a wavelength of 532 nm. Thereby, a second groove 36 is formed in the laminated film of the first power generation layer 11, the second power generation layer 21, and the second electrode layer 6. The second open groove 36 passes through the second electrode layer 6, the second power generation layer 21, and the first power generation layer 11. The second open groove 36 is provided on the same side as the first open groove 34 with respect to the electrode open groove 31 and further away from the first open groove 34. Laser irradiation may be performed from the second electrode layer 6 side. This state is shown in FIG.

  Since the integrated tandem junction solar cell of the present invention has the current blocking portion 5 as described above, the low resistance layer (n layer 16) of the first power generation layer 11 and the p layer 22 of the second power generation layer 21. It becomes possible to cut off the lateral running of the current. Further, the current blocking portion 5 can be formed simultaneously with the formation of the first groove 34 or by adding a slight process. That is, the short-circuit current Isc and the fill factor FF in the power generation cell 8 can be improved at a low cost without making a significant process change. And module efficiency of an integrated tandem junction solar cell can be improved.

  In the present embodiment, the intermediate layer 10 is used, but the same effect can be obtained even when the intermediate layer 10 is not provided.

(Second Embodiment)
First, the structure of 2nd Embodiment of the integrated tandem junction solar cell of this invention is demonstrated with reference to an accompanying drawing. FIG. 4 is a cross-sectional view showing the configuration of the second embodiment of the integrated tandem junction solar cell of the present invention. This embodiment is different from the first embodiment in that the material and manufacturing method of the current blocking portion 5a are different.

The current blocking portion 5a extends from the surface of the second power generation layer so as to reach the first electrode layer 4 so as to be in contact with the end of the first power generation layer 11 and the second power generation layer 21 on the first open groove 34 side. Yes. The first power generation layer 11 and the second power generation layer 21 are provided between the end portion on the first groove 34 side and the second electrode layer 6 of the first groove 34. It may also be provided on the opposite side of the first open groove 34. It has a resistivity (or resistance higher than a preset value) higher than a preset value. The current blocking unit 5 is exemplified by an insulator such as an ultraviolet curable resin or a thermosetting resin. The width is, for example, 10 μm. The resistance value of the current blocking unit 5 is the same as in the first embodiment.
The current blocking unit 5 causes current to run laterally in the low resistance layer (the low resistance layer of the first power generation layer 11 and the p layer 12 of the second power generation layer 21) (current leakage in a direction parallel to the surface of the substrate). Thus, reaching the second electrode layer 6 can be prevented.

  Since other configurations are the same as those in the first embodiment, the description thereof is omitted.

  Since the operation of the second embodiment of the integrated tandem junction solar cell of the present invention is the same as that of the first embodiment, the description thereof is omitted.

  Next, a second embodiment of the method for manufacturing an integrated tandem junction solar cell of the present invention will be described with reference to the accompanying drawings. 5 and 4 are cross-sectional views showing a second embodiment of the method for producing an integrated tandem junction solar cell of the present invention.

First, a laminated film having the electrode groove 31 and the first groove 34 is formed on the substrate 2 by the process described in FIGS. 2 and 3A, which is the same as that in the first embodiment. .
Next, in the state shown in FIG. 3A, an ultraviolet curable resin is applied so as to be embedded in the first groove 34, and an ultraviolet ray is irradiated to form the insulating portion 5a ′. This state is shown in FIG.

  Next, the insulating portion 5a 'is removed while the side surfaces of the first open groove 34 on the first power generation layer 11 and second power generation layer 21 side are not exposed. Thereby, the first open groove 34 reaching the first electrode layer 4 from the surface is formed again. This state is shown in FIG. This corresponds to FIG. 3B of the first embodiment.

  Since the subsequent processes are the same as those in the first embodiment, the description thereof is omitted.

  In FIGS. 5A and 5B, an ultraviolet curable resin is used. However, it is possible to use other materials for forming the insulator. For example, a thermosetting resin can be used. That is, in the state of FIG. 3A, the thermosetting resin is applied so as to be embedded in the first open groove 34 and irradiated with an electron beam (or heated in the furnace) to form the insulating portion 5a '. The subsequent process is similar.

Also in this embodiment, the same effect as that of the first embodiment can be obtained.
In the present embodiment, the intermediate layer 10 is used, but the same effect can be obtained even when the intermediate layer 10 is not provided.

(Third embodiment)
First, the configuration of the third embodiment of the integrated tandem junction solar cell of the present invention will be described with reference to the accompanying drawings. FIG. 6: is sectional drawing which shows the structure of 3rd Embodiment of the integrated tandem junction solar cell of this invention. The integrated tandem junction solar cell includes a substrate 4 and a plurality of power generation cells 8-i (i = 1 to n, n is a natural number and the number of power generation cells).

  In the present embodiment, the current blocking unit 5 is not provided, and the n layer 16 and the intermediate layer 10 of the first power generation layer 11 and the first layer 34 are formed between the electrode groove 31 and the first groove 34 (for example, 20 μm). The second embodiment differs from the first embodiment in that each layer of the p layer 22 of the power generation layer 21 is removed. That is, by preventing each of the low resistance n layer 16, the intermediate layer 10, and the p layer 22 from easily leaking current in the lateral direction from reaching the second electrode layer 6 of the first groove, Prevent current leakage.

  When performing the above-described removal, between the electrode groove 31 and the first groove 34, the remaining p layer 12 and i layer 14 in the first power generation layer 11, and i layer 24 in the second power generation layer 21 and The resistance combined with the n layer 26 is set as follows. That is, the magnitude of this resistance is such that the voltage drop due to the resistance from the electrode open groove 31 to the first open groove 34 when a lateral leakage current flows is about the open circuit voltage of the second power generation layer 21 or more. Is set as follows. This is because the lateral leakage current is so small that it cannot be ignored or no longer flows. In the case of the power generation cell 8 as in the present embodiment, it is preferably 10Ω or more per 1 cm length.

  Each configuration removes each layer of the n layer 16 and the intermediate layer 10 of the first power generation layer 11 and the p layer 22 of the second power generation layer 21 between the electrode open groove 31 and the first open groove 34. Others are the same as those in the first embodiment, and the description thereof is omitted.

  Next, since the operation of the third embodiment of the integrated tandem junction solar cell of the present invention is the same as that of the first embodiment, the description thereof is omitted.

  Next, a third embodiment of the method for producing an integrated tandem junction solar cell of the present invention will be described with reference to the accompanying drawings. FIG. 7: is sectional drawing which shows embodiment of the 3rd manufacturing method of the integrated tandem junction solar cell of this invention.

As shown in FIG. 7A, SnO ₂ having a film thickness of 0.5 μm as the first electrode layer 4 is formed on the substrate 2 so as to cover the substrate ₂ by a thermal CVD method.

  In the state of FIG. 7A, the laser is irradiated from the substrate 2 side in the atmosphere using a YAG laser or YVO4 laser having a wavelength of 532 nm (second harmonic) or a wavelength of 1064 nm (fundamental wave). Thereby, an electrode open groove 31 is formed in the first electrode layer 4. The electrode open groove 31 passes through the first electrode layer 4. Laser irradiation may be performed from the first electrode layer 4 side.

  Subsequently, p-type a-SiC / i-type a-Si as the p-layer 12 / i-layer 14 / n-layer 16 of the first power generation layer 11 so as to cover the first electrode layer 4 and the electrode groove 31. / N-type μc-Si is laminated in this order by the PCVD method. The thickness of each film is 10 nm / 200 nm / 50 nm, respectively. Next, ZnO as the intermediate layer 10 is formed by sputtering so as to cover the n-type μc-Si. The film thickness is 100 nm. Then, p-type μc-Si as the p layer 22 of the second power generation layer 21 is formed by the PCVD method so as to cover the first power generation layer 11. The film thickness is 30 nm.

  Next, Ar ion beam is irradiated from the p layer 22 side of the second power generation layer 21. Thereby, the n layer 16 of the first power generation layer 11, the intermediate layer 10, and the p layer 22 of the second power generation layer 21 between the electrode open groove 31 and the first open groove 34 (planned) are removed. This state is shown in FIG.

  Accordingly, by removing each of the n layer 16 and the intermediate layer 10 of the first power generation layer 11 and the p layer 22 of the second power generation layer 21 between the electrode open groove 31 and the first open groove 34, It becomes possible to prevent current leakage in the direction.

  Subsequently, the i-type μc-Si / n-type as the i layer 24 / n layer 26 of the second power generation layer 21 so as to cover the i layer 14 of the first power generation layer 11 and the p layer 22 of the second power generation layer 21. μc-Si is laminated in this order by the PCVD method. The film thickness of each film is 2 μm / 50 nm.

  Next, the laser is irradiated from the substrate 2 side in the atmosphere using a YAG laser or YVO4 laser having a wavelength of 532 nm. Thereby, the first open groove 34 is formed. The first open groove 34 penetrates the second power generation layer 21 and the first power generation layer 11. The first groove 34 is on the side of another power generation cell 8-i + 1 adjacent to the electrode groove 31. Laser irradiation may be performed from the second power generation layer 21 side.

  Thereafter, the ZnO / Ag laminated film as the second electrode layer 6 is sputtered in this order so as to cover the surface of the second power generation layer 21 and the inner surface of the first open groove 34 (or fill the inner surface). Form with. The thickness of each film is 100 nm / 0.3 μm. Thereby, in the 1st open groove 34, the 2nd electrode layer 6 and the 1st electrode layer 4 of other adjacent electric power generation cell 8-i + 1 are electrically connected.

  Then, using a YAG laser or YVO4 laser with a wavelength of 532 nm, the laser is irradiated from the substrate 2 side in the atmosphere. Thereby, a second groove 36 is formed in the laminated film of the first power generation layer 11, the second power generation layer 21, and the second electrode layer 6. The second open groove 36 passes through the second electrode layer 6, the second power generation layer 21, and the first power generation layer 11. The second open groove 36 is provided on the same side as the first open groove 34 with respect to the electrode open groove 31 and further away from the first open groove 34. Laser irradiation may be performed from the second electrode layer 6 side. This state is shown in FIG.

  As described above, the integrated tandem junction solar cell of the present invention includes the n layer 16 and the intermediate layer 10 of the first power generation layer 11 and the second power generation layer 21 between the electrode open groove 31 and the first open groove 34. Since each layer of the p layer 22 is removed, it is possible to block the lateral current flow in the low resistance layer (n layer 16) of the first power generation layer 11 and the p layer 22 of the second power generation layer 21. The above process can be formed by adding a few processes. That is, the short-circuit current Isc and the fill factor FF in the power generation cell 8 can be improved at a low cost without making a significant process change. And module efficiency of an integrated tandem junction solar cell can be improved.

  In the present embodiment, the intermediate layer 10 is used, but the same effect can be obtained even when the intermediate layer 10 is not provided.

(Fourth embodiment)
First, the structure of 4th Embodiment of the integrated tandem junction solar cell of this invention is demonstrated with reference to an accompanying drawing. FIG. 8: is sectional drawing which shows the structure of 4th Embodiment of the integrated tandem junction solar cell of this invention. The integrated tandem junction solar cell includes a substrate 4 and a plurality of power generation cells 8-i (i = 1 to n, n is a natural number and the number of power generation cells).

  In the present embodiment, the n layer 16 and the intermediate layer 10 of the first power generation layer 11 and the p layer 22 of the second power generation layer 21 are formed between the electrode open groove 31 and the first open groove 34 (for example, 20 μm). The third embodiment is different from the third embodiment in that the resistance is increased without removing each layer. That is, for each layer of the low resistance n layer 16, the intermediate layer 10, and the p layer 22 in which current is likely to leak in the lateral direction, the high resistance n layer 16 b and the middle between the first groove 34 and the first groove 34. By using the layer 10b and the p layer 22b, current leakage in the lateral direction is prevented.

  The n layer 16 b is provided on the i layer 14 on the extension of the n layer 16 parallel to the substrate 2 between the electrode opening 31 and the first opening 34. The n layer 16 is altered with a laser or the like to increase the resistance. The conductivity of the n layer 16b is so low that the lateral current leaking to the second electrode layer 6 of the first groove 34 is less than or equal to a predetermined amount (high resistance).

  The intermediate layer 10 b is provided on the n layer 16 b on the extension of the intermediate layer 10 parallel to the substrate 2 between the electrode open groove 31 and the first open groove 34. The intermediate layer 10 is altered with a laser or the like to increase resistance. The conductivity of the intermediate layer 10 is so low that the lateral current leaking to the second electrode layer 6 of the first groove 34 is less than or equal to a predetermined amount (high resistance).

  The p layer 22 b is provided on the intermediate layer 10 b on the extension of the p layer 22 parallel to the substrate 2 between the electrode groove 31 and the first groove 34. The p layer 22 is altered by a laser or the like to increase the resistance. The conductivity of the p layer 22b is so low that the lateral current leaking to the second electrode layer 6 of the first groove 34 is less than or equal to a predetermined amount (high resistance).

When performing the above alteration, the sheet resistance of each of the altered layers (n layer 16b, intermediate layer 10b, and p layer 22b) between the electrode open groove 31 and the first open groove 34 is as follows: It is determined in this way. That is, the magnitude of this resistance is such that the voltage drop due to the resistance from the electrode open groove 31 to the first open groove 34 when a lateral leakage current flows is about the open circuit voltage of the second power generation layer 21 or more. Is set as follows. This is because the lateral leakage current is so small that it cannot be ignored or no longer flows. In the case of the power generation cell 8 as in the present embodiment, the sheet resistance is preferably 10 ⁵ Ω / □ or more. Alternatively, the conductivity of the material is preferably 10 S / cm or less.

The above numerical values are calculated as follows, for example.
If the voltage drop ΔV due to the resistance from the electrode open groove 31 to the first open groove 34 when the horizontal leak current flows becomes equal to or higher than the open circuit voltage Voc of the second power generation layer 21, the horizontal leak current I The problem disappears.
Here, Voc = 0.6V, lateral leakage current per unit area I = 1 mA / cm ² (assuming 1/10 of the short-circuit current Isc), width 1 cm, and length from the electrode opening groove 31 to the first opening. Assuming 0.01 cm (100 μm) to the groove 34, the sheet resistance R is
ΔV = I × (R × 0.01)> 0.6
Therefore,
R> 6 × 10 ⁴ Ω
Therefore, R is preferably 10 ⁵ Ω / □ or more.

  Since each other structure is the same as that of the third embodiment, the description thereof is omitted.

  Next, since the operation of the fourth embodiment of the integrated tandem junction solar cell of the present invention is the same as that of the third embodiment, the description thereof is omitted.

  Next, regarding the fourth embodiment of the method for manufacturing an integrated tandem junction solar cell of the present invention, the n layer 16, the intermediate layer 10, and the p layer between the electrode open groove 31 and the first open groove 34. Except for increasing the resistance without removing each layer 22, the description is omitted because it is the same as in the third embodiment.

  However, the increase in resistance is performed as follows. In the state of FIG. 7A, a laser is irradiated from the substrate 2 side in the atmosphere using a YAG laser or YVO4 laser having a wavelength of 532 nm. Thereby, the n layer 16 of the first power generation layer 11, the intermediate layer 10, and the p layer 22 of the second power generation layer 21 between the electrode open groove 31 and the first open groove 34 (scheduled) are altered, and high Resistive n layer 16b, intermediate layer 10b, and p layer 22b are used.

Also in this embodiment, the same effect as that of the third embodiment can be obtained.
In the present embodiment, the intermediate layer 10 is used, but the same effect can be obtained even when the intermediate layer 10 is not provided.

(Fifth embodiment)
First, the structure of 5th Embodiment of the integrated tandem junction solar cell of this invention is demonstrated with reference to an accompanying drawing. FIG. 9: is sectional drawing which shows the structure of 5th Embodiment of the integrated tandem junction solar cell of this invention. The integrated tandem junction solar cell includes a substrate 4 and a plurality of power generation cells 8-i (i = 1 to n, n is a natural number and the number of power generation cells).

  This embodiment does not partially increase the resistance of each of the n layer 16 and the intermediate layer 10 of the first power generation layer 11 and the p layer 22 of the second power generation layer 21, but increases the resistance of the entire layers. This is different from the fourth embodiment. In other words, the low resistance n layer 16, the intermediate layer 10, and the p layer 22, which easily leak current in the lateral direction, are changed to the high resistance n layer 16 a, the intermediate layer 10 a, and the p layer 22 a, thereby Prevent current leakage.

When the resistance of each layer is increased, the sheet resistance of each layer (n layer 16a, intermediate layer 10a, and p layer 22a) is set as follows. That is, the magnitude of this resistance is such that the voltage drop due to the resistance from the electrode open groove 31 to the first open groove 34 when a lateral leakage current flows is about the open circuit voltage of the second power generation layer 21 or more. Is set as follows. This is because the lateral leakage current is so small that it cannot be ignored or no longer flows. In the case of the power generation cell 8 as in the present embodiment, the sheet resistance from the electrode open groove 31 to the first open groove 34 is preferably 10 ⁵ Ω / □ or more. Alternatively, the conductivity of the material is preferably 10 S / cm or less. This is the same reason as in the fourth embodiment.

  The n layer 16 a is provided on the i layer 14. It is an n-type microcrystalline semiconductor film formed by a film forming method such as a PCVD method. In this embodiment, n-type μc-Si and a film thickness of 15 to 100 nm are used as the n-type microcrystalline semiconductor film. The resistance of the n layer 16a is approximately the same as that of the p layer 12 and the i layer 14, and is higher than in the other embodiments. That is, the resistance is so high that the lateral current leaking to the second electrode layer 6 of the first open groove 34 becomes a predetermined amount or less. As a method of increasing, the dopant concentration is decreased or the film thickness is decreased.

The intermediate layer 10a is provided so as to cover the n layer 16a. It is a transparent conductive film formed by a film forming method such as a thermal CVD method or a sputtering method. Examples of the transparent conductive film include SnO ₂ (tin oxide), ITO (indium tin oxide), and ZnO (zinc oxide). In this embodiment, it is ZnO having a thickness of 30 to 200 nm. The resistance of the intermediate layer 10a is higher than in the other embodiments. That is, the resistance is so high that the lateral current leaking to the second electrode layer 6 of the first open groove 34 becomes a predetermined amount or less. As a method for increasing the thickness, the film forming conditions are changed or the film thickness is reduced.

  The p layer 22a is provided on the first power generation layer 11a. It is a p-type microcrystalline semiconductor film formed by a film forming method such as a PCVD method. In this embodiment mode, p-type μc-Si having a thickness of 5 to 50 nm is used as the p-type microcrystalline semiconductor film. The resistance of the p layer 22a is about the same as that of the i layer 24, and is higher than in the other embodiments. That is, the resistance is so high that the lateral current leaking to the second electrode layer 6 of the first open groove 34 becomes a predetermined amount or less. As a method of increasing, the dopant concentration is decreased or the film thickness is decreased.

  Since each other structure is the same as that of the fourth embodiment, the description thereof is omitted.

  Next, since the operation of the fifth embodiment of the integrated tandem junction solar cell of the present invention is the same as that of the fourth embodiment, the description thereof is omitted.

  Next, in the fifth embodiment of the manufacturing method of the integrated tandem junction solar cell of the present invention, the n layer 16, the intermediate layer 10, and the p layer 22 are not partially made highly resistive. Except for changing the film forming conditions (including control of film quality) of the n layer 16a, the intermediate layer 10a, and the p layer 22a, the description thereof will be omitted.

  In the integrated tandem junction solar cell of the present invention, the resistances of the n layer 16 and the intermediate layer 10 of the first power generation layer 11 and the p layer 22 of the second power generation layer 21 are increased as described above. It is possible to block the lateral current flow in the low resistance layer (n layer 16) of the first power generation layer 11 and the p layer 22 of the second power generation layer 21. The above process can be formed by adding a few processes. That is, the short-circuit current Isc and the fill factor FF in the power generation cell 8 can be improved at a low cost without making a significant process change. And module efficiency of an integrated tandem junction solar cell can be improved.

  In the present embodiment, the intermediate layer 10 is used, but the same effect can be obtained even when the intermediate layer 10 is not provided.

  The present invention also provides a multi-junction solar in which a back electrode (referred to as a back surface in the sense of being opposite to light incidence) is formed on a metal substrate and the like, and a power generation layer and a light incident side transparent conductive film are formed thereon. The same applies to batteries.

FIG. 1 is a cross-sectional view showing a configuration of a first embodiment of an integrated tandem junction solar cell of the present invention. 2A to 2C are cross-sectional views illustrating a first embodiment of a method for manufacturing an integrated tandem junction solar cell of the present invention. 3A to 3C are cross-sectional views illustrating a first embodiment of a method for manufacturing an integrated tandem junction solar cell of the present invention. FIG. 4 is a cross-sectional view showing the configuration of the second embodiment of the integrated tandem junction solar cell of the present invention. 5 (a) to 5 (b) are cross-sectional views showing a second embodiment of the method for producing an integrated tandem junction solar cell of the present invention. FIG. 6: is sectional drawing which shows the structure of 3rd Embodiment of the integrated tandem junction solar cell of this invention. FIGS. 7A to 7B are cross-sectional views showing a third embodiment of the method for manufacturing an integrated tandem junction solar cell of the present invention. FIG. 8: is sectional drawing which shows the structure of 4th Embodiment of the integrated tandem junction solar cell of this invention. FIG. 9: is sectional drawing which shows the structure of 5th Embodiment of the integrated tandem junction solar cell of this invention. FIG. 10 is a cross-sectional view showing the structure of an integrated tandem junction integrated solar cell using a conventional silicon thin film.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Integrated tandem junction solar cell 2 Substrate 4 First electrode layer 6 Second electrode layer 8 (-i: i = 1 to n, n is a natural number and the number of power generation cells) Power generation cell 10 Intermediate layer 11 First power generation layer 12 , 22 p layer 14, 24 i layer 16, 26 n layer 21 second power generation layer 31 groove for electrode 34 first groove 36 second groove 102 glass substrate 104 transparent electrode film 106 metal back electrode film 110 intermediate layer 111 First power generation layer 112, 122 p layer 114, 124 i layer 116, 126 n layer 121 second power generation layer 131 electrode groove 134 first groove 136 second groove

Claims (17)

A substrate,
A plurality of power generation cells provided on the substrate and connected in series with each other;
Comprising
Each of the plurality of power generation cells is
A first electrode layer provided on the substrate;
A first power generation layer provided on the first electrode layer and generating power by light;
A second power generation layer provided on the first power generation layer and generating power by light;
A second electrode layer provided on the second power generation layer,
An electrode groove extending from the surface of the first electrode layer to the substrate, a first groove extending from the surface of the second power generation layer to the first electrode layer, and a surface of the second electrode layer to the first electrode layer A second groove extending,
The second groove is separated from the first groove on the same side as the first groove with respect to the electrode groove,
The second electrode layer is connected to the first electrode layer through the first groove so as to be connected in series to another adjacent one of the plurality of power generation cells,
The part from the said electrode groove | channel to the said 1st groove | channel in the said 1st electric power generation layer and the said 2nd electric power generation layer has resistance value more than predetermined | prescribed resistance value An integrated tandem junction solar cell. The integrated tandem junction solar cell according to claim 1,
The predetermined resistance value is obtained when a lateral current flows from the first power generation layer and the second power generation layer to the second electrode layer of the first groove, and the first power generation layer and the second power generation layer. The integrated tandem junction solar cell is set so that the voltage drop from the first groove to the first groove is equal to or higher than the open circuit voltage of the second power generation layer. The integrated tandem junction solar cell according to claim 1 or 2,
Each of the plurality of power generation cells further includes a high resistance portion provided between the respective end portions of the first power generation layer and the second power generation layer and the second electrode layer in the first groove. ,
The part from the said electrode groove | channel on the said 1st electric power generation layer and the said 2nd electric power generation layer containing the said high resistance part has a resistance value more than the said predetermined resistance value The integrated tandem junction solar cell. The integrated tandem junction solar cell according to claim 1 or 2,
The first power generation layer is
A first semiconductor layer provided on the first electrode layer;
A second semiconductor layer provided on the first semiconductor layer;
A third semiconductor layer provided on the second semiconductor layer,
The second power generation layer
A fourth semiconductor layer provided on the first power generation layer;
A fifth semiconductor layer provided on the fourth semiconductor layer;
A sixth semiconductor layer provided on the fifth semiconductor layer,
The third semiconductor layer has a lower resistance than the first semiconductor layer and the second semiconductor layer,
The fourth semiconductor layer has a lower resistance than the fifth semiconductor layer,
Of the third semiconductor and the fourth semiconductor layer, the resistivity of the part from the vicinity of the electrode groove to the first groove is higher than the resistivity of the other part. Integrated tandem junction solar cell. The integrated tandem junction solar cell according to claim 1 or 2,
The first power generation layer is
A first semiconductor layer provided on the first electrode layer;
A second semiconductor layer provided on the first semiconductor layer;
A third semiconductor layer provided on the second semiconductor layer,
The second power generation layer
A fourth semiconductor layer provided on the first power generation layer;
A fifth semiconductor layer provided on the fourth semiconductor layer;
A sixth semiconductor layer provided on the fifth semiconductor layer,
The third semiconductor layer has a lower resistance than the first semiconductor layer and the second semiconductor layer,
The fourth semiconductor layer has a lower resistance than the fifth semiconductor layer,
Of the third semiconductor and the fourth semiconductor, a portion from the vicinity of the electrode groove to the first groove is removed. An integrated tandem junction solar cell. The integrated tandem junction solar cell according to claim 4 or 5,
The first power generation layer includes a conductive intermediate layer provided on a side in contact with the second power generation layer. An integrated tandem junction solar cell. The integrated tandem junction solar cell according to any one of claims 4 to 6,
The integrated semiconductor tandem junction solar cell, wherein the first semiconductor layer is a low-resistance layer having one of a p-type conductivity and an n-type conductivity. The integrated tandem junction solar cell according to claim 7,
The first semiconductor layer is an integrated tandem junction solar cell including microcrystalline silicon. The integrated tandem junction solar cell according to claim 7 or 8,
The second semiconductor layer and the fifth semiconductor layer are layers having an intrinsic type,
The third semiconductor layer is a layer having a conductivity type different from the first semiconductor layer of p-type and n-type,
The fourth semiconductor layer is a low-resistance layer having a conductivity type of either p-type or n-type,
The sixth semiconductor layer is a layer having a conductivity type different from that of the fourth semiconductor layer of p-type and n-type. An integrated tandem junction solar cell. (A) forming an electrode groove extending from the surface of the first electrode layer provided on the substrate to the substrate;
(B) On the first electrode layer, a step of laminating a first power generation layer that generates power by light and a second power generation layer that generates power by light in this order;
(C) forming a first groove extending from the surface of the second power generation layer to the first electrode layer;
(D) forming a high resistance portion having a resistance value higher than a predetermined resistance value on a side surface on the first groove side in the first power generation layer and the second power generation layer;
(E) forming a second electrode layer on the second electrode layer and the first groove;
(F) forming a second groove extending from the surface of the second electrode layer to the first electrode layer;
The second groove is separated from the first groove on the same side as the first groove with respect to the electrode groove,
The second electrode layer is connected to the first electrode layer through the first groove so that the second power generation layer is connected in series to another adjacent first power generation layer separated by the second groove. A method of manufacturing an integrated tandem junction solar cell. In the manufacturing method of the integrated tandem junction solar cell according to claim 10,
The step (d) includes:
(D1) An integrated tandem junction solar cell comprising a step of physically or chemically modifying the end portions of the first groove on the first power generation layer and second power generation layer side to form the high resistance portion. Manufacturing method. In the manufacturing method of the integrated tandem junction solar cell according to claim 10,
The step (d) includes:
(D2) burying an insulator in the first groove;
(D3) forming an additional first groove extending from the surface of the insulator to the first electrode layer;
With
A method of manufacturing an integrated tandem junction solar cell, wherein the insulator is provided on a side surface of the first power generation layer and the second power generation layer on the side of the additional first groove. (G) forming an electrode groove extending from the surface of the first electrode layer provided on the substrate to the substrate;
(H) On the first electrode layer, the first semiconductor layer, the second semiconductor layer, and the third semiconductor layer of the first power generation layer that generates power by light, and the fourth semiconductor of the second power generation layer that generates power by light Laminating layers in this order;
(I) increasing a resistance value of the third semiconductor layer and the fourth semiconductor layer from above the electrode groove to a predetermined position;
(J) laminating a fifth semiconductor layer and a sixth semiconductor layer of the second power generation layer in this order on the fourth semiconductor layer;
(K) forming a first groove extending from the surface of the sixth semiconductor layer to the first electrode layer;
(L) forming a second electrode layer on the sixth semiconductor layer and the first groove;
(M) forming a second groove extending from the surface of the second electrode layer to the first electrode layer,
The third semiconductor layer has a lower resistance than the first semiconductor layer and the second semiconductor layer,
The fourth semiconductor layer has a lower resistance than the fifth semiconductor layer,
The second groove is separated from the first groove on the same side as the first groove with respect to the electrode groove,
The second electrode layer is connected to the first electrode layer through the first groove so that the second power generation layer is connected in series to another adjacent first power generation layer separated by the second groove. And
The predetermined position is between the position where the first groove is formed and the second groove. A method for manufacturing an integrated tandem junction solar cell. (N) forming an electrode groove extending from the surface of the first electrode layer provided on the substrate to the substrate;
(O) On the first electrode layer, the first semiconductor layer, the second semiconductor layer, and the third semiconductor layer of the first power generation layer that generates power by light, and the fourth semiconductor of the second power generation layer that generates power by light Laminating layers in this order;
(P) removing the third semiconductor layer and the fourth semiconductor layer from the electrode groove to a predetermined position;
(Q) laminating a fifth semiconductor layer and a sixth semiconductor layer of the second power generation layer in this order on the fourth semiconductor layer and the second semiconductor layer;
(R) forming a first groove extending from the surface of the sixth semiconductor layer to the first electrode layer;
(S) forming a second electrode layer on the sixth semiconductor layer and the first groove;
(T) forming a second groove extending from the surface of the second electrode layer to the first electrode layer;
The third semiconductor layer has a lower resistance than the first semiconductor layer and the second semiconductor layer,
The fourth semiconductor layer has a lower resistance than the fifth semiconductor layer,
The second groove is separated from the first groove on the same side as the first groove with respect to the electrode groove,
The second electrode layer is connected to the first electrode layer through the first groove so that the second power generation layer is connected in series to another adjacent first power generation layer separated by the second groove. And
The predetermined position is between the position where the first groove is formed and the second groove. A method for manufacturing an integrated tandem junction solar cell. (U) forming an electrode groove extending from the surface of the first electrode layer provided on the substrate to the substrate;
(V) a first semiconductor layer, a second semiconductor layer, and a third semiconductor layer of a first power generation layer that generates power by light on the first electrode layer; a fourth semiconductor layer of a second power generation layer that generates power by light; Laminating a fifth semiconductor layer and a sixth semiconductor layer in this order;
(W) forming a first groove extending from the surface of the sixth semiconductor layer to the first electrode layer;
(X) forming a second electrode layer on the sixth semiconductor layer and the first groove;
(Y) forming a second groove extending from the surface of the second electrode layer to the first electrode layer;
The third semiconductor layer has a resistance comparable to the first semiconductor layer and the second semiconductor layer,
The fourth semiconductor layer has a resistance comparable to the fifth semiconductor layer,
The second groove is separated from the first groove on the same side as the first groove with respect to the electrode groove,
The second electrode layer is connected to the first electrode layer through the first groove so that the second power generation layer is connected in series to another adjacent first power generation layer separated by the second groove. And
A method for manufacturing an integrated tandem junction solar cell. In the manufacturing method of the integrated tandem junction solar cell according to any one of claims 13 to 15,
The first semiconductor layer is a low-resistance layer having one of a p-type conductivity and an n-type conductivity,
The second semiconductor layer is an intrinsic type layer,
The method for producing an integrated tandem junction solar cell, wherein the third semiconductor layer is a layer having a conductivity type different from that of the first semiconductor layer of p-type and n-type. In the manufacturing method of the integrated tandem junction solar cell according to claim 16,
The fourth semiconductor layer is a low-resistance layer having a conductivity type of either p-type or n-type,
The fifth semiconductor layer is a layer having an intrinsic type,
The method for producing an integrated tandem junction solar cell, wherein the sixth semiconductor layer is a layer having a conductivity type different from that of the fourth semiconductor layer of p-type and n-type.

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