JP2002280580A - Integrated photovoltaic device and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an integrated photovoltaic device manufacturing method which prevents process failures of a backside electrode film, even if an amorphous semiconductor layer constituting a photoelectric conversion layer is made thin. SOLUTION: The method for manufacturing an integrated photovoltaic device having transparent electrodes 2, an amorphous or microcrystal semiconductor photoelectric conversion layer 3 having at least one junction and backside electrodes 4 laminated one above another on a transparent substrate 1 wherein each layer other than a substrate is separated in a plurality of regions in each forming stage to connect them in series, is constituted by forming a transparent conductive film 4a on the conversion layer 3, irradiating the upside of the conductive film 4a with a laser beam to separate it into a plurality of regions, and forming a metal film 4b on the transparent conductive electrode film 4a by electroplating using the transparent electrode film 4a as one electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an integrated photovoltaic device and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a transparent substrate such as glass, Sn
A transparent electrode such as O ₂ , having at least one junction
A back electrode composed of a photoelectric conversion layer made of an amorphous semiconductor or a microcrystalline semiconductor such as -Si or a-SiGe, a transparent conductive oxide film, a metal layer, and the like is sequentially laminated, and at each stage during the formation, A so-called amorphous integrated photovoltaic device is known as a photovoltaic device connected in series by separating each layer other than the substrate into a plurality of regions.

In order to form an integrated structure, it is necessary to separate a transparent conductive film, an a-Si film, and a metal electrode film on a glass substrate. As a method for separating each film, a laser patterning method using a laser is mainly used (for example, see Japanese Patent Publication No. 4-64473).

A method of manufacturing an integrated photovoltaic device using a conventional laser patterning method will be described with reference to FIG.
FIG. 4 is an enlarged cross-sectional view of a main part showing a method of manufacturing a conventional integrated photovoltaic device for each process, focusing on an adjacent space where two photoelectric conversion elements are electrically connected in series.

[0005] forming an insulating translucent _{ITO (In 2 Sn 2 O 3} ) on one main surface of the substrate 1 and the transparent electrode 2 made of SnO ₂ such as glass, for example, a transparent electrode by irradiation of a laser beam 2 is divided into strips in an arbitrary number of steps (FIG. 4
(A)). Then, a photoelectric conversion layer 3 made of an amorphous semiconductor layer such as an a-Si film having a pin junction inside is deposited on the divided transparent electrode 2 (see FIG. 4B).

After that, a laser beam is irradiated from the other main surface side of the substrate 1 along the division line of the transparent conductive film 2 so as not to overlap with the division line, and the amorphous semiconductor in the photoelectric conversion layer 3 is irradiated. The hydrogen in the layer is rapidly released, and the release of the hydrogen removes the amorphous semiconductor layer to divide the photoelectric conversion layer 3 (see FIG. 4C).

Subsequently, a transparent conductive film 4 is formed on the photoelectric conversion layer 3.
1. A back electrode 4 made of a back metal electrode film 42 of aluminum or the like is formed, and the transparent conductive film 2 and the back electrode 4 are connected (see FIG. 4D). Thereafter, a laser beam is irradiated from the other main surface side of the substrate 1 along the division line of the transparent electrode 2 and the photoelectric conversion layer 3 so as not to overlap with both division lines. The hydrogen in the layer 3 is rapidly released, and the amorphous semiconductor layer, the transparent conductive film 41 thereon, and the back metal electrode film
Is removed to separate adjacent cells (see FIG. 4E).

[0008]

By the way, as the film thickness of the amorphous semiconductor layer is optimized and the development of a stacked photovoltaic device using a narrow band gap material is advanced with the countermeasures against light deterioration and the improvement of the conversion efficiency, Amorphous semiconductor layers are becoming thinner.

With the thinning of the amorphous semiconductor layer, the absolute amount of hydrogen in the amorphous semiconductor layer becomes insufficient during patterning of the back electrode, and the back electrode film is not completely removed. . In particular, when the thickness of the amorphous semiconductor layer becomes 3000 Å or less, processing defects due to a shortage of the absolute amount of hydrogen in the amorphous semiconductor layer become remarkable. As a result, characteristics such as an open-circuit voltage (Voc) and a fill factor (FF) were reduced.

The present invention has been made in consideration of the above-mentioned conventional problems, and has been made in consideration of the above circumstances.
An object of the present invention is to provide an integrated photovoltaic device and a method for manufacturing the same, which prevent the occurrence of processing defects in the back electrode film.

[0011]

According to the present invention, a first electrode, a photoelectric conversion layer made of an amorphous or microcrystalline semiconductor having at least one junction, and a second electrode are sequentially laminated on a substrate. An integrated photovoltaic device connected in series by separating each layer into a plurality of regions, wherein the electrode serving as the back surface side electrode of the first or second electrode is made of a transparent conductive film and a metal film; And the metal film is formed so as to cover an upper surface and side surfaces of the transparent conductive film.

The metal film can be formed by an electroplating method using the transparent conductive film as one electrode.

As described above, the transparent conductive film forming part of the back electrode is separated, and the metal layer film forming part of the back electrode is formed by electroplating using the transparent conductive film as one electrode. Therefore, the back electrode can be formed uniformly only on the transparent conductive film, and the back electrode can be formed without adversely affecting the separation of the back electrode.

According to the present invention, a transparent electrode, a photoelectric conversion layer made of an amorphous or microcrystalline semiconductor having at least one junction, and a back electrode are sequentially laminated on a light-transmitting substrate. A method for manufacturing an integrated photovoltaic device connected in series by separating each layer other than the substrate into a plurality of regions in the step, wherein a transparent conductive film is formed on the photoelectric conversion layer, After separating into multiple areas,
A metal film is formed on the transparent conductive film by an electroplating method using the transparent conductive film as one electrode.

Further, the transparent conductive film is configured to be irradiated with a laser from the film side to be separated into a plurality of regions.

As described above, the back electrode is separated by laser-separating the transparent conductive film constituting a part of the back electrode from the film side, so that the transparent conductive film does not depend on the film thickness of the photoelectric conversion layer. It is possible to perform backside electrode separation. Further, since the metal layer constituting a part of the back electrode is formed by the electroplating method using the transparent conductive film as one electrode, the metal layer is uniformly formed only on the transparent conductive film and adversely affects the separation of the back electrode. Absent. Further, with this metal layer, it is possible to increase the backside light reflection and improve Isc as in the conventional case. Therefore, the output characteristics of the photoelectric conversion element can be significantly improved.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. Note that the same reference numerals are given to the same parts as those in the related art.

FIG. 1 is a sectional view showing an integrated photovoltaic device according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view showing a method of manufacturing the integrated photovoltaic device according to the present invention in each step. It is a figure and mainly shows the adjacent space | interval part which connects two photoelectric conversion elements electrically in series.

The transparent electrode film 2 made of SnO ₂ is formed by thermal CVD on one main surface of the insulating translucent substrate 1 made of glass, the transparent electrode film 2, for example, by irradiation of a laser beam It is divided into strips of an arbitrary number of stages.

A photoelectric conversion layer 3 made of an amorphous semiconductor having a pin junction inside is formed on the transparent electrode film 2 by plasma C.
It is formed by the VD method. The total thickness of the photoelectric conversion layer 3 is 3000 ° or less as described later. The photoelectric conversion layer 3 is formed on the transparent conductive film 2 from the other main surface side of the substrate 1.
The laser beam is irradiated along the divided line so that the laser beam is not overlapped with the divided line.

On the photoelectric conversion layer 3, zinc oxide (Zn)
A transparent conductive film 4a made of O) is provided, and the transparent conductive film 4a is divided by irradiating a laser beam from the transparent conductive film 4a side so as not to overlap with the division line. Then, by using the divided transparent conductive film 4a as one electrode, nickel (Ni) is provided on the upper and side surfaces of the transparent conductive film 4a by electroplating, and the back metal film 4b is provided.

The feature of the present invention resides in that the back electrode 4 is composed of the transparent conductive film 4a and the back metal film 4b formed by electroplating using the transparent conductive film 4a. That is, in this embodiment, only the transparent conductive film 4a made of ZnO that constitutes a part of the back electrode 4 is separated from the film side. For this reason, good processing separation can be performed without depending on the total film thickness of the photoelectric conversion layer 3. further,
The optical loss on the back side can be prevented by forming the back metal film 4b made of a Ni layer by electroplating after processing and separating the ZnO film forming a part of the back electrode.

With the above configuration, the transparent conductive film 4a
Will remain without being removed. However, since the photoelectric conversion layer 3 is formed of an amorphous semiconductor, electrical isolation between adjacent back electrodes can be ensured.

Although the ZnO film is inferior in water resistance, in this embodiment, the side surface of the ZnO film is covered with the back metal film 4b made of Ni. For this reason, the water resistance at the interface between the ZnO film and the photoelectric conversion layer 3 at the separation portion can be improved.

Next, a method of manufacturing an integrated photovoltaic device using a laser patterning method according to an embodiment of the present invention will be described with reference to FIG.

According to the embodiment of the present invention, a film having a thickness of 0.2 to 1 μm is formed on one main surface of an insulating and translucent substrate 1 made of glass.
m, in this embodiment, a transparent electrode film 2 made of SnO ₂ having a thickness of 8000 ° is formed by a thermal CVD method or the like.
Thereafter, the transparent electrode film 2 is divided into strips of an arbitrary number of steps by laser beam irradiation (see FIG. 2A). This laser patterning is performed using Nd: YAG having a wavelength of 1.06 μm.
A laser was used at a pulse frequency of 3 kHz and room temperature at a laser power density of 2 × 10 ⁸ W / cm ² .

Then, a photoelectric conversion layer 3 made of an amorphous semiconductor layer having a pin junction inside and having a total thickness of about 3000 ° is deposited on the transparent electrode film 2 (see FIG. 2B). The photoelectric conversion layer 3 was formed by sequentially laminating a p-layer, an i-layer, and an n-layer by the plasma CVD method under the conditions shown in Table 1 below. The formation of the photoelectric conversion layer 3 (p-layer, i-layer, and n-layer) was performed using a known parallel-plate plasma CVD apparatus. Here, the discharge electrode area is 1500 cm ² , and the electrode interval is 40 mm.

[0028]

[Table 1]

After that, a laser beam is irradiated from the other main surface side of the substrate 1 along the division line of the transparent electrode film 2 so as not to overlap with the division line, thereby forming the amorphous layer constituting the photoelectric conversion layer 3. Hydrogen in the semiconductor layer is rapidly released, the amorphous semiconductor layer is removed by the release of the hydrogen, and the photoelectric conversion layer 3 is divided (see FIG. 2C). This laser patterning was performed using a YAG laser (second harmonic) having a wavelength of 0.53 μm, a pulse frequency of 3 kHz, and a laser power density of 8 × 10 ⁶ W / cm ² at room temperature.

At the time of this laser patterning, the absolute amount of hydrogen in the amorphous semiconductor layer is insufficient and the photoelectric conversion layer 3
Even if the separation is not sufficient, if a part of the transparent electrode film 2 is exposed, it can be electrically connected to the back electrode film 4 formed in the next step, so that there is no problem.

Subsequently, on the photoelectric conversion layer 3, a transparent conductive film 4 a constituting a part of the back electrode 4 is formed to a thickness of 1000
Was formed by a DC magnetron sputtering method (see FIG. 2D). This ZnO film is made of 3 wt% Al
_The substrate temperature was set to 20 using a 2O ₃ -doped ZnO target.
0 ° C., reaction pressure 1 Pa, gas flow rate Argon (Ar): 4
The film was formed under the conditions of 00 sccm, oxygen (O ₂ ): 10 sccm, and power of 0.1 kW.

Subsequently, the transparent conductive film 4a is arranged along the division line so as not to overlap with each division line.
By irradiating a laser beam from the transparent conductive film 4a side, the transparent conductive film 4a is removed, and the transparent conductive film 4a is divided (FIG. 2).
(E)). This laser patterning has a wavelength of 0.2
Using a 48 μm excimer laser and a pulse frequency of 100
The laser power density was 10 W / cm ² at room temperature and at room temperature.

As described above, in this embodiment, the transparent conductive film 4a made of ZnO, which constitutes a part of the back electrode, is separated from the film side. For this reason, good processing separation can be performed without depending on the total film thickness of the photoelectric conversion layer 3.

Thereafter, using the transparent conductive film 4a as one electrode (negative electrode), a metal electrode film 4b constituting a part of the back electrode is formed by electroplating. In this embodiment, the metal electrode film 4b made of Ni is formed only on the transparent conductive film 4a by forming nickel (Ni) by electroplating. As a result, the metal electrode film 4b is formed on the transparent conductive film 4a and on the side surface portion, so that the light reflection on the back side is increased as in the related art, and the back electrode separation is not adversely affected.

Nickel was used as the metal electrode formed by the electroplating method. In this method, electrolytic plating is performed in a plating bath using a mixed solution of nickel sulfate, nickel chloride, and boric acid with the transparent conductive film 4a constituting a part of the back surface electrode 4 as a negative electrode, for about 3000 seconds for about 30 seconds.
Was formed on the ZnO film constituting a part of the back electrode.

Next, a photovoltaic device according to the present invention and a conventional photovoltaic device were prepared, and the results of measuring solar cell characteristics are shown in Table 2. Both devices are 35-stage integrated photovoltaic devices, and light is incident from the substrate. The embodiment of the present invention is formed by the above method, and the conventional apparatus is formed by the conventional method of manufacturing the back electrode shown in FIG. This conventional apparatus uses, as a metal electrode film 42 constituting a part of a back electrode, aluminum (Al) having a thickness of 3000 ° formed by a sputtering method.
Patterned from the substrate side by laser patterning. This laser patterning has a wavelength of 0.53
Using a μm YAG laser (second harmonic), at a pulse frequency of 3 kHz and at room temperature, a laser power density of 1 × 10 ⁷ W / c
It was carried out in m ^2. In other configurations, the conventional device and the device of the present invention have the same configuration. The output characteristics of these devices are AM
It was measured under the conditions of −1.5, 100 mW / cm ² and 25 ° C.

[0037]

[Table 2]

It can be seen that, in this embodiment, the solar cell characteristics are significantly improved in comparison with the conventional example. In the present embodiment, even when the total thickness of the photoelectric conversion layer 3 is as thin as 2400 °,
Laser processing separation does not matter. This is because, in the conventional example, a laser beam is incident from the glass side, the laser beam is absorbed in the photoelectric conversion layer, and the back electrode is melted and scattered by the release of hydrogen contained in the photoelectric conversion layer as a driving force, thereby separating the back electrode. Therefore, when the total thickness of the photoelectric conversion layer is small, the absolute amount of hydrogen is small, and the force for melting and scattering the back electrode is weakened, and sufficient processing separation cannot be performed. On the other hand, in the present embodiment, since only ZnO constituting a part of the back electrode is separated from the film side, good processing separation can be performed without depending on the total film thickness of the photoelectric conversion layer. Become. Further, by forming a Ni layer by electroplating after processing and separating ZnO constituting a part of the back electrode, optical loss on the back side can be prevented, and a decrease in Isc can be prevented. Due to these, Voc, F.R. F.
Can be greatly improved, and the output characteristics have been greatly improved.

In this embodiment, ZnO is used as the transparent conductive film constituting a part of the back electrode. However, other transparent conductive oxides, for example, SnO ₂ , ITO and the like may be used.

In this embodiment, Ni is used as a metal which forms a part of the back electrode and is formed by the electroplating method. In addition, a metal such as Cu, Cr, Zn, Sn and Ag is used. Is also good.

Next, according to a second embodiment of the present invention,
This will be described with reference to FIG. 1 and 2 are so-called forward-type photovoltaic devices in which light is incident from the substrate side, whereas the one shown in FIG. 3 is a so-called forward-type photovoltaic device in which light is incident from the direction opposite to the substrate. The present invention is applied to a reverse type photovoltaic device.

As shown in FIG. 3, a back side electrode 12 is placed on a substrate 11 made of a metal substrate or the like whose surface is subjected to insulation treatment.
A transparent conductive film 12a made of ZnO, which constitutes a part of the above, is formed. This ZnO film is made of 3 wt% Al ₂ O ₃ doped Z
Using an nO target, a substrate temperature of 200 ° C., a reaction pressure of 1 Pa, a gas flow rate of argon (Ar): 400 sccm,
Oxygen (O ₂ ) was formed under the conditions of 10 sccm and power of 0.1 kW.

Subsequently, the transparent conductive film 12a is irradiated with a laser beam from the side of the transparent conductive film 12a along the division line to remove the transparent conductive film 12a.
Split. This laser patterning has a wavelength of 0.24.
Using an 8 μm excimer laser, pulse frequency 100H
z, at room temperature with a laser power density of 10 W / cm ² .

Thereafter, a metal electrode film 12b constituting a part of the back electrode is formed by electroplating using the transparent conductive film 12a as a negative electrode. In this embodiment, the metal electrode film 12b made of Ni is formed only on the transparent conductive film 12a by forming nickel (Ni) by electroplating. As a result, the back electrode 12 is provided on the substrate 11 by patterning.

Then, a nip is internally formed on the backside electrode 12.
A photoelectric conversion layer 13 made of an amorphous semiconductor layer having a junction and a total thickness of about 3000 ° is deposited. The photoelectric conversion layer 13 has a plasma C under the conditions shown in Table 3 below.
An n-layer, an i-layer, and a p-layer were sequentially formed by a VD method. The formation of the photoelectric conversion layer 13 (the n-layer, the i-layer, and the p-layer) was performed using a known parallel-plate plasma CVD apparatus. here,
The discharge electrode area is 1500 cm ² and the electrode interval is 40 mm.

[0046]

[Table 3]

Thereafter, a laser beam is irradiated from the main surface side of the substrate 1 along the division line of the back electrode 12 so as not to overlap the division line, thereby dividing the photoelectric conversion layer 13.

Subsequently, on the photoelectric conversion layer 13, a ZnO film,
A transparent electrode 14 made of an ITO film or the like is formed, and the transparent electrode 14 is irradiated with a laser beam from the transparent electrode 14 side along the division line so as not to overlap with each division line to remove the transparent conductive film. Then, the transparent electrode 14 is divided.

In this manner, the integrated photovoltaic device of the reverse type shown in FIG. 3 can be formed.

[0050]

As described above, in the present invention, since the back electrode is separated by separating the transparent conductive film constituting a part of the back electrode from the film side, the present invention depends on the thickness of the photoelectric conversion layer. Without this, good backside electrode separation can be performed. Further, since the metal layer forming a part of the back electrode is formed by an electroplating method using the transparent conductive film as one electrode, it is uniformly formed only on the transparent conductive film and does not adversely affect the separation of the back electrode. . And with this metal layer, as before,
It is possible to increase Isc by increasing the backside light reflection. Therefore, the output characteristics of the photoelectric conversion element are greatly improved. F. Can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a photovoltaic device according to a first embodiment of the present invention.

FIG. 2 is a fragmentary enlarged cross-sectional view showing a method of manufacturing the integrated photovoltaic device according to the present invention for each step.

FIG. 3 is a sectional view showing a photovoltaic device according to a second embodiment of the present invention.

FIG. 4 is an enlarged sectional view of a main part showing a method for manufacturing a conventional integrated photovoltaic device for each process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulated translucent substrate 2 Transparent electrode film 2 3 Photoelectric conversion layer 3 4 Back electrode 4a Transparent conductive film 4b Back metal film

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4M104 AA08 BB04 BB13 BB36 CC01 DD37 DD42 DD43 DD52 DD75 FF13 GG05 GG20 HH20 5F051 AA05 BA17 CA15 CB27 DA04 EA01 EA03 EA09 EA10 EA11 EA16 FA03 FA04 FA06 GA03

Claims (4)

[Claims] 1. A first electrode, a photoelectric conversion layer made of an amorphous or microcrystalline semiconductor having at least one junction, and a second electrode are sequentially stacked on a substrate, and each layer is separated into a plurality of regions. An integrated photovoltaic device connected in series, wherein, among the first or second electrodes, an electrode serving as a back side electrode is made of a transparent conductive film and a metal film, and the metal film is An integrated photovoltaic device formed to cover an upper surface and side surfaces of a transparent conductive film. 2. The integrated photovoltaic device according to claim 1, wherein the metal film is formed by an electroplating method using the transparent conductive film as one electrode. 3. A transparent electrode, a photoelectric conversion layer made of an amorphous or microcrystalline semiconductor having at least one junction, and a back electrode are sequentially laminated on a translucent substrate. Is a method for manufacturing an integrated photovoltaic device connected in series by separating each layer into a plurality of regions, wherein a transparent conductive film is formed on the photoelectric conversion layer, and the transparent conductive film is formed on the plurality of regions. A method for manufacturing an integrated photovoltaic device, comprising forming a metal film on a transparent conductive film by electroplating using the transparent conductive film as one electrode after separation. 4. The method for manufacturing an integrated photovoltaic device according to claim 3, wherein the transparent conductive film is separated into a plurality of regions by irradiating a laser from the film side.