JP3102232B2 - Thin film solar cell and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin-film solar cell having a photoelectric conversion layer composed of a thin film of an amorphous semiconductor containing a Group 4 element of the periodic table such as silicon as a main component, and a method of manufacturing the same.

[0002]

2. Description of the Related Art The electrode on the light incident side of a thin-film solar cell must be a transparent electrode. However, the transparent conductive material thin film constituting the transparent electrode has a high sheet resistance, and when a current flows through the transparent electrode for a long distance, the Joule loss cannot be ignored. Therefore, the width of a unit solar cell having one photoelectric conversion layer is limited to 4 to 20 mm, and a large-area transparent electrode cannot be formed. On the other hand, Heisei 5 related to the applicant's application
In the thin film solar cell shown in FIG. 2 described in Japanese Patent Application No. 78382, the area of a unit solar cell having one photoelectric conversion layer can be increased. In the figure, the insulating film substrate 1 has a through hole 21 having a radius of about 0.5 mm,
The first electrode layer 3 made of an Al thin film, the thin film semiconductor layer 4 made of an amorphous semiconductor, and the second electrode layer 5 made of ZnO are laminated on the front surface, and also on the back surface.
A third electrode layer 6 made of an Al thin film is formed. In this case, the Al thin film and ZnO thin film
The second electrode layer 5 and the third electrode layer 6 overlap and are electrically connected in the through hole 21 as shown in the figure, since they also adhere to the inner surface of 21. At the end, the first electrode layer 3 and the third electrode layer 6 are connected through the through hole 22 without forming the thin film semiconductor layer 4 and the second electrode layer 5, and the third electrode layer at the end is formed.
If the 62 is separated from the third electrode layer 6 at the center, the output can be taken out from the third electrode layer 6 and the third electrode layer 62 on the same plane, and the distance of the current flowing through the transparent conductive film is maximum. ,
Since it is half of the distance between through holes, Joule loss is reduced. In order to obtain a high output voltage, such a structure formed on a large-area substrate is divided into a plurality of unit solar cells,
The connection is made in series by the connection between the third electrode layers.

[0003]

An easy-to-process film is used for the substrate 1 of the thin-film solar cell shown in FIG. 2, and the first electrode layer 3 is conventionally formed on the substrate 1 to form the through hole 2. After forming the entire surface, a mechanical method using a punch or a method using an energy beam such as a YAG laser has been used. However, the method of mechanically drilling the substrate through hole 2 using a punch tends to cause burrs and the like on the processed back surface, and mechanical distortion occurs on the first electrode layer 3 around the processed portion, and the insulating substrate 1 And the first electrode layer 3 is easily peeled around the processed portion, which causes pinholes and the like.
When a laser is used, heat damage occurs. For this reason, the substrate 1 and the first electrode layer 3 are easily peeled off at the heat-damaged portion in the vicinity of the processed portion, which also causes a pinhole or the like, which lowers the yield.

As another manufacturing method, there is a method of first forming a through hole in a substrate, and then forming a laminated structure on the front surface and a third electrode layer on the back surface. In this case, after forming the first electrode layer, it is necessary to remove the first electrode layer on the inner surface of the through hole and the peripheral portion. However, if mechanical or thermal distortion during processing of the through-hole remains in the periphery of the through-hole or scattered matter adheres during laser processing, the substrate and the first electrode layer are likely to peel off, and The shape of the removed portion of the electrode layer may be incorrect or cause a pinhole in the upper layer. The above-described problem of separation also exists between the third electrode layer and the substrate.

An object of the present invention is to solve the above-mentioned problems and to provide a thin-film solar cell in which separation between a substrate and an electrode layer formed thereon does not occur around a processed portion, and a method of manufacturing the same.

[0006]

In order to achieve the above-mentioned object, the present invention provides a method for forming a first electrode layer, a semiconductor layer and a second electrode layer on one surface of an insulating substrate, and a third electrode layer on the other surface. An electrode layer is provided, the second electrode layer is transparent, and the second electrode layer and the third electrode layer are dispersed at substantially equal intervals in the semiconductor layer, the first electrode layer, and the insulating substrate. In the thin-film solar cell connected through the through-hole, an intermediate layer for improving the adhesion to the substrate is interposed between the substrate and the first and third electrode layers. It is effective that the insulating substrate is a plastic film and the intermediate layer is made of a metal oxide or a silicon compound. The present invention also provides a first electrode layer on one surface of an insulating substrate, a laminate of a semiconductor layer and a second electrode layer, a third electrode layer on the other surface, the second electrode layer is transparent, the second electrode The method for manufacturing a thin-film solar cell, wherein the layer and the third electrode layer are connected to the semiconductor layer, the first electrode layer, and the insulating substrate through through holes that are dispersed and opened at substantially equal intervals, wherein the insulating substrate After opening the through-hole, at least the surface of the periphery of the through-hole of the substrate is contacted with plasma generated in a gas containing at least one of oxygen, nitrogen and argon, and then the first electrode layer, Semiconductor layer,
The second electrode layer and the third electrode layer are formed on the surface of the substrate.

[0007]

The adhesion between the first and third electrode layers and the insulating substrate, for example, a metal oxide layer or a silicon compound layer when the substrate is a plastic material is improved. By interposing the intermediate layer, when the through hole is formed in the substrate after the formation of the electrode layer, the substrate and the electrode layer do not peel around the processed portion due to mechanical or thermal strain, and the electrode after the formation of the through hole is formed. Even when the layer is provided, the electrode layer does not peel around the through hole. On the other hand, when the electrode layer is formed after the through-hole is formed in the substrate, thermal or mechanically damaged portions generated in advance in the peripheral portion of the substrate or scattered matters attached to the peripheral portion of the substrate can be removed by plasma processing. The adhesion between the subsequently formed electrode layer and the substrate is improved.

[0008]

1 (a) to 1 (g) show a manufacturing method according to an embodiment of the present invention in accordance with the flow of manufacturing steps. 2 are denoted by the same reference numerals. Fig. 1 (a)
1 shows a cross-sectional view of a substrate. Although an aramid film having a thickness of 50 μm was used as the substrate 1 in this embodiment, polyether sulfone (PES), polyethylene naphthalate (P
EN), polyethylene terephthalate (PET), and an insulating plastic film such as polyimide. As shown in FIG. 1B, a plurality of substrate through holes 21 and 22 are formed in predetermined positions of the substrate 1 by using the second harmonic of a YAG laser. The shapes of the substrate through holes 21 and 22 do not necessarily have to be circular. For example, in order to improve the characteristics of a solar cell, the area of the substrate through holes 21 and 22 is as small as possible, and the peripheral length is as long as possible. A longer shape is better. The processing of the through holes 21 and 22 does not necessarily need to be the second harmonic of the YAG laser, and is also effective with a method using another energy beam such as a fundamental wave of the YAG laser, a fourth harmonic, and an excimer laser. . Next, although not shown, the substrate 1 is subjected to a plasma treatment in a gas containing oxygen to remove scattered matter generated by processing around the through holes 21 and 22 and a portion damaged by heat. The plasma treatment is performed, for example, in a mixed gas atmosphere of Ar + O ₂ at a pressure of 0.
The insulating substrate surface is sputtered by a reverse sputtering method in a range of about 1 to 0.001 Torr. At this time, the discharge power and the substrate temperature can be arbitrarily selected depending on the balance with the processing time and the processing state. The discharge gas is a single gas of Ar gas, N ₂ gas and O ₂ gas, or
Even if a mixed gas obtained by a combination of the respective gases is used, the scattered matter generated by the processing around the substrate through holes 21 and 22 and the portion damaged by heat can be similarly removed.

A first electrode layer 3 made of Ag is formed thereon, and a third electrode layer 6 is formed on the surface opposite to the first electrode layer 3 by sputtering to a thickness of several hundred nm (FIG. 1 (c)). In addition, as a material, a multilayer film such as an Al film or an Ag / transparent conductive film can be used. Either the first electrode layer 3 or the third electrode layer 6 may be used first, but each electrode layer is formed after the plasma treatment without fail.

When the electrodes are formed by the above-described method, since the heat-affected zone and the scattered matter around the processing of the substrate through holes 21 and 22 are removed, the distance between the substrate 1 and each of the electrode layers 3 and 6 is reduced. Adhesive force is improved. Further, by forming the first electrode layer 3 and the third electrode layer 6 continuously in a vacuum after performing the plasma treatment, the effect can be further enhanced. next,
The periphery of the substrate through hole 21 of the first electrode layer 3 is irradiated with a laser beam, and the first electrode layer 3 in the portion 7 is removed (FIG. 1D).
].

After these steps, a thin film semiconductor layer 4 to be a photoelectric conversion layer is formed. In this embodiment, hydrogenated amorphous silicon (a-Si: H) based material deposited by a normal glow discharge decomposition method is used to form n from the substrate side.
An -ip junction was formed [FIG. 1 (e)]. A transparent electrode layer 5 as a second electrode layer is formed thereon. This layer has IT
An oxide conductive film such as O or ZnO can be used.
In this embodiment, an ITO film formed by a sputtering method was used [FIG.
(f)]. At this time, the film is not formed in the through hole 22 at the end by covering the film with a mask when forming the film.
Next, an auxiliary third electrode layer made of a metal film or the like by covering the third electrode layer 6 on the substrate surface opposite to the surface on which the solar cell is formed
61 is finally formed. In this embodiment, the material is Al or
Film formation was performed by a sputtering method using Ag and Cr [Fig. 1 (g).
]. The auxiliary third electrode layer 61 is for ensuring electrical connection between the third electrode 6 and the second electrode layer 5.

Finally, to form a series structure, the solar cell is removed in a predetermined pattern by a YAG laser and divided into unit solar cells. The characteristics of the solar cell fabricated in this manner show good characteristics with little leakage current. Further, in another embodiment of the present invention shown in FIG. 3 in which a solar cell can be manufactured with high yield without peeling of the first electrode layer 3 and the third electrode layer 6 in the peripheral portion of the processing, FIG. c) before the first electrode layer 3 and the third electrode layer 6 are formed on the substrate 1 after the plasma treatment of c), the intermediate layer 8 is interposed between the substrate 1 and the first and third electrode layers 3 and 6, respectively. Is inserted. This middle layer 8
As the conductive metal oxide film such as ZnO, ITO, SnO ₂ , and InO ₃ or the insulating silicon compound film such as SiN and SiO, the adhesive force between the plastic film and the metal film of the electrode layer is used. Serve to improve Therefore,
Such an intermediate layer is formed on the insulating substrate before the through holes 21 and 22 are formed, and the first electrode layer 3 or the third electrode layer 6 is formed thereon. It is possible to prevent the first electrode layer or the third electrode layer from peeling off when the holes are formed. However, even when the first electrode layer or the third electrode layer is formed after the through hole is formed, if this intermediate layer is inserted, the adhesion of the first and third electrode layers to the substrate is improved, and the Improve battery reliability.

[0013]

According to the present invention, a transparent electrode layer on one surface of a substrate is connected to an electrode layer on the other surface through a through hole in the substrate to reduce the distance of a current flowing through the transparent electrode layer having a large sheet resistance. Improving the adhesion between the solar cell substrate and the electrode layer by the intermediate layer, or, after forming the through-hole, performing a plasma treatment on the periphery thereof to improve the adhesion with the electrode layer formed thereafter. As a result, peeling of the electrode layer in the vicinity of the through hole can be suppressed, and a solar cell having good characteristics can be manufactured with high yield.

[Brief description of the drawings]

FIG. 1 shows a manufacturing process of a thin-film solar cell according to one embodiment of the present invention.
Sectional views shown in the order of (a) to (g)

FIG. 2 is a cross-sectional view of the thin-film solar cell described in the specification of the prior application.

FIG. 3 is a cross-sectional view of a thin-film solar cell according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating substrate 21, 22 Through hole 3 First electrode layer 4 Thin film semiconductor layer 5 Transparent electrode layer (second electrode layer) 6 Third electrode layer 61 Auxiliary third electrode layer 7 First electrode layer removal part 8 Intermediate layer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 31/04-31/078

Claims (3)

(57) [Claims] A first electrode layer, a laminated body of a semiconductor layer and a second electrode layer on one surface of an insulating substrate, a third electrode layer on the other surface, wherein the second electrode layer is transparent, The layer and the third electrode layer are connected to the semiconductor layer, the first electrode layer and the insulating substrate through through-holes dispersed and formed at substantially equal intervals, and the first electrode layer and the third electrode A thin-film solar cell, comprising an intermediate layer between the layer and the substrate, the intermediate layer improving the adhesion to the substrate. 2. The thin-film solar cell according to claim 1, wherein the insulating substrate is a plastic film, and the intermediate layer is made of a metal oxide or a silicon compound. 3. A laminate comprising a first electrode layer, a semiconductor layer and a second electrode layer on one surface of an insulating substrate, a third electrode layer on the other surface, wherein the second electrode layer is transparent, The method for manufacturing a thin-film solar cell, wherein the layer and the third electrode layer are connected to the semiconductor layer, the first electrode layer, and the insulating substrate through through holes that are dispersed and opened at substantially equal intervals, wherein the insulating substrate After drilling the through-hole, at least the surface of the periphery of the through-hole of the substrate is contacted with plasma generated in a gas containing at least one of oxygen, nitrogen or argon, and then the first electrode layer, A method for manufacturing a thin-film solar cell, comprising forming a semiconductor layer, a second electrode layer, and a third electrode layer on a surface of a substrate.