JP2002231986A - Method for manufacturing integrated thin film solar battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an integrated thin film solar battery which can prevent electric insulating failures between a first electrode film and a second electrode film. SOLUTION: In a process for manufacturing the integrated thin film solar battery where a plurality of unit cells 5 obtained by sequentially laminating first electrode films 2, semiconductor films 3 and second electrode films 4 on a substrate 1 are connected in series, a laser beam and the thin film solar battery are relatively moved while the thin film solar battery is irradiated with the single pulse high repetitive laser beam. Thus, the laser beam 21 whose pulse width is not more than 20 ns and the edge rise width of intensity distribution is not more than 7 μm is used as the laser beam when an open groove for removing the second electrode films 4 and the semiconductor films 3 is disposed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention manufactures an integrated thin-film solar cell in which a plurality of unit cells, which are formed by sequentially laminating a first electrode film, a semiconductor film, and a second electrode film on a substrate, are connected in series. It is about the method.

[0002]

2. Description of the Related Art Generally, a thin film solar cell has a structure in which a semiconductor film is sandwiched between a transparent electrode film and a back electrode film, and converts the energy of light incident from the transparent electrode film side into electric energy in the semiconductor film. . The transparent electrode film is made of SnO2
(Tin oxide), ITO (indium tin oxide) or Z
The back electrode film is formed of a transparent conductive film made of nO (zinc oxide) or the like.
It is formed of a metal such as Mo.

The electrical resistivity of the transparent electrode film is about two orders of magnitude higher than that of the back electrode film made of metal, for example, about 5 × 1.
0 ⁻⁴ Ω · cm. Therefore, a power loss occurs while the current generated in the semiconductor film flows through the transparent electrode, and the loss becomes more remarkable as the area of the transparent electrode film increases.

Therefore, an integrated thin-film solar cell has been proposed in which a plurality of unit cells in which a first electrode film, a semiconductor film, and a second electrode film are sequentially laminated on a substrate are connected in series. According to this integrated thin-film solar cell, since the transparent electrode film is divided, power loss due to the transparent electrode can be reduced.

[0005]

In the process of manufacturing the above-mentioned integrated thin-film solar cell, a first electrode film, a semiconductor film, and a second electrode film are sequentially laminated on a substrate, and then a laser beam is applied thereto. A step of irradiating the film to form a groove and thereby form a plurality of unit cells connected in series is included. The grooves are formed by a laser scribe method.
That is, it is formed by fixing the irradiation position of the laser beam and moving the battery body, or by fixing the battery body and moving the laser beam.

Since high energy is required for the groove by the laser beam, a method of intermittently irradiating the film surface with a pulsed laser beam is employed. However, conventionally, since the pulse width of the laser beam to be applied is large, in particular, in the step of providing an opening in the second electrode (backside electrode) film to realize the independence of each unit cell and the series connection of these cells. , The energy of the laser beam extends to the lower first electrode (transparent electrode), and as a result, there arises a problem that the electrical resistance between the back electrode film and the transparent electrode film is reduced by the influence of so-called ablation deposition. .

[0007] That is, due to the energy of the laser beam acting on the transparent electrode film, the material constituting the transparent electrode film is blown in a state of being decomposed into atomic, molecular, and cluster forms (aggregates), and is blown. There is a disadvantage that a substance adheres between the two electrodes to cause a reduction in the electric resistance.

On the other hand, in the prior art, a laser beam having an energy distribution of Gaussian distribution, that is, a laser beam whose energy attenuates in the radial direction is condensed and irradiated. Even if it can be removed, the energy threshold required for film removal in the peripheral part (energy density when the substance reaches the melting point or more and melts when applying energy to the material to be processed, and reaches the boiling point or more and begins to be evaporated and removed) Is not obtained, and as a result, a problem that a groove of a predetermined width cannot be processed, and a beam spread,
Problems such as adversely affecting the heat in the vicinity of the processed portion also occur.

The present invention has been made in view of such a situation, and is intended to manufacture an integrated thin-film solar cell capable of preventing poor electrical insulation between a first electrode film and a second electrode film. It is intended to provide a way.

[0010]

According to a first aspect of the present invention, there is provided an integrated thin-film solar cell in which a plurality of unit cells formed by sequentially laminating a first electrode film, a semiconductor film, and a second electrode film on a substrate are connected in series. In the process of manufacturing the battery, while irradiating the thin-film solar cell with a single-pulse high-repetition rate laser beam, the laser beam and the thin-film solar cell are relatively moved to remove the second electrode film and the semiconductor film. When the groove is provided, a laser beam having a pulse width of 20 ns or less and an edge rising width of the intensity distribution of 7 μm or less is used as the laser beam.

In a second aspect based on the above aspect, the pulse width is 10 ns or less and the edge rising width is 5 ns.
μm or less. A third invention is characterized in that, in each of the above inventions, the laser beam is visible light having a wavelength of 400 to 650 nm.

According to a fourth aspect of the present invention, in each of the above aspects, a YAG laser, a YVO laser,
It is characterized by using a laser and a YLF laser.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a manufacturing procedure of an integrated thin-film solar cell will be described with reference to FIG. (1) As shown in FIG. 1A, a first electrode film 2 is formed on an electrically insulating substrate 1. (2) A laser beam is projected on the first electrode film 2 to form a groove A in the electrode film 2. (3) As shown in FIG. 1B, a semiconductor film 3 having a PIN structure made of amorphous silicon, microcrystalline silicon, or the like is formed on the first electrode film 2 having the groove A. (4) A laser beam is projected on the semiconductor film 3 to form an opening B in the semiconductor film. (5) As shown in FIG. 1C, a second electrode film 4 is formed on the semiconductor film 3 having the groove B. (6) By projecting a laser beam on the second electrode film 4,
After the electrode film 4 and the semiconductor film 3 are removed, a groove C is formed.

In the integrated thin-film solar cell manufactured by the above procedure, as shown in FIG. 1C, a first electrode film 2, a semiconductor film 3, and a second electrode film 4 are sequentially laminated. A plurality of unit cells 5 are connected in series via the connecting portions 5a including the grooves A, B, and C.

In the integrated thin-film solar cell, the surface of the groove C on the unit cell 5 side, that is, FIG.
The quality of the laser processing on the right inner surface of the groove C shown in (c) greatly affects the performance. That is, a short pulse high repetition laser beam is used as a laser beam irradiated to form the groove C. When the pulse width of the laser beam is large, one laser beam is used.
Since the irradiation time for each shot becomes longer, the first electrode film 2
Up to the energy of the laser beam.

In this case, the components of the first electrode film 2 scatter in a decomposed state, and the first electrode film 2 and the second electrode film 4
And a phenomenon of adhesion (ablation deposition described above) occurs. This phenomenon significantly lowers the electric resistance between the first electrode film 2 and the second electrode film 4 and thus causes a reduction in the performance of the integrated thin-film solar cell.

On the other hand, when the energy distribution of the laser beam is Gaussian, the periphery of the groove C is also irradiated with the laser beam due to the spread of the laser beam. In this case, the electric resistance of the semiconductor film 3 located near the right side of the groove C is reduced by heating. And
This lowers the electrical resistance between the first electrode film 2 and the second electrode film 4 and thus causes a reduction in the performance of the integrated thin-film solar cell. Therefore, when forming the groove C with a laser beam, it is necessary to pay attention to the pulse width of the laser beam and the rising width of the edge of the intensity distribution.

FIG. 2 illustrates the relationship between the pulse width of the laser beam and the insulation resistance between the first electrode film 2 and the second electrode film 4, and FIG. The relationship between the rising width of the edge of the beam intensity distribution and the insulation resistance between the first electrode film 2 and the second electrode film 4 is illustrated. These relationships are all obtained by experiments. According to these experimental results, it is desirable that the laser beam for processing the groove C has a pulse width of 20 ns or less and a rising width of an edge of the intensity distribution of 7 μm or less.

FIG. 4 conceptually shows an example of the configuration of a laser beam irradiation apparatus for obtaining a laser beam satisfying the above conditions. The laser beam irradiation apparatus includes a laser 10 for emitting a laser beam 11 and a laser beam 1
1 for adjusting the intensity distribution and the like.
The laser 10 is a short-pulse high-repetition laser that generates a laser beam 11 having a pulse width of 20 ns or less and a wavelength of 400 to 650 nm in a visible light range.
A YAG laser, a YVO laser, a YLF laser, or the like is applied.

The optical system 20 has a distribution characteristic of the beam energy intensity of the laser beam 11 as shown in FIG. 5, that is, the rising width W of the beam edge is 7 μm.
The following distribution characteristics are adjusted.
A concave lens 22 for enlarging the laser beam 11 having a circular cross section emitted from the lens, a convex lens 23 for converting the beam expanded by the concave lens 22 into a parallel beam, a mask 24 for blocking a peripheral portion of the parallel beam to obtain a beam having a rectangular cross section, A mirror 25 for reflecting the beam passing through the mask 24, and
An objective lens 26 for condensing the beam reflected by the mirror 25 is provided.

The laser beam 21 emitted from the optical system 20 has a pulse width of 20 ns or less and a rising width of an edge of the intensity distribution of 7 μm or less. The irradiation area of the laser beam 21 has a rectangular shape as shown in FIG. Note that the intensity distribution shown in FIG.
-On the A line.

In the embodiment of the present invention, the groove C is formed by the laser beam 21. Laser processing of the groove C is performed on the semiconductor film 3 and the groove B shown in FIG.
This is performed after the electrode film 4 is formed. That is, FIG.
With the right edge of the laser beam 21 shown in FIG. 5 positioned at the right edge of the processing area shown in FIG. 5, the workpiece (integrated thin film solar cell in the manufacturing process) and the laser beam 21 are connected to each other in FIG. It is relatively moved in a direction perpendicular to the paper (the direction of the arrow in FIG. 6).

Since the laser beam 21 is obtained based on the short pulse repetitive laser beam 11 emitted from the laser 10, the film to be processed (the second electrode film 4 and the semiconductor film 3) is intermittently irradiated. I do. For this reason, the speed of the relative movement is appropriately set so that a non-irradiated portion of the laser beam 21 does not exist in the processing region and energy sufficient for removing the processing target film is applied to the processing region. There is a need.

Therefore, in this embodiment, the laser beam 21 at the next irradiation timing is placed at a half of the irradiation range of the laser beam 21 at a certain irradiation timing (see the solid line in FIG. 6).
Are set so that half of the irradiation range (see the chain line in FIG. 6) overlap. When the relative moving speed is set as described above, the entire continuous processing area is irradiated twice with the laser beam 21.
In addition, this irradiation frequency is determined by the energy of the laser or
It is necessary to change the thickness appropriately according to the thickness of the back electrode and the semiconductor layer.

As described above, according to this embodiment,
Since the groove C is processed by the laser beam 21 having a pulse width of 20 ns or less and a rising width of an edge of the intensity distribution of 7 μm or less, the first electrode film 2 and the second electrode film 4 in the unit cell 5 are processed. The insulation resistance between them is kept sufficiently high.

That is, when the laser beam 21 having a pulse width of 20 ns is used, the energy of the laser beam 21 does not reach the first electrode film 2 strongly.
Each of the above electrode films 2 and 4 due to scattering of the components of the first electrode film 2
A decrease in insulation resistance between the two is suppressed. Further, the laser beam 21 having a rising width of the edge of the intensity distribution of 7 μm or less.
Is used, the irradiation amount of the laser beam to the periphery of the processing region is drastically reduced. Therefore, a decrease in the electric resistance of the semiconductor film 3 located on the groove C side of the unit cell 5 is suppressed, and the unit cell 5 , A high insulation resistance can be provided between the first electrode film 2 and the second electrode film 4. Therefore, according to this embodiment, it is possible to manufacture an integrated thin-film solar cell having high photoelectric conversion efficiency.

As is apparent from FIGS. 2 and 3, when the pulse width of the laser beam 21 is 10 ns or less, and when the rising width of the edge of the intensity distribution of the laser beam 21 is 5 μm or less, the unit is The insulation resistance between the first electrode film 2 and the second electrode film 4 in the cell 5 can be more stably increased. Therefore, in order to manufacture a highly reliable and high-performance integrated thin-film solar cell with good yield, a laser 10 having a pulse width of 10 ns or less is used as the laser 10 and an optical system 20 is used. It is preferable to use one that can reduce the rising width of the edge of the intensity distribution of the laser beam 21 to 5 μm or less.

The laser beam 21 of the above embodiment is
Is a laser beam in the visible light region having a wavelength of 400 to 650 nm. If such a laser beam in the visible light region is used, damage to the first electrode film 2 is reduced, and the quality and characteristics of the integrated thin-film solar cell are improved.

[0029]

According to the first aspect of the present invention, the pulse width is 2
0 ns or less and the edge rising width of the intensity distribution is 7 μm
Since the following laser beam is used, a high-performance integrated thin-film solar cell having high insulation resistance between the first electrode film and the second electrode film in the unit cell can be manufactured.

According to the second aspect of the present invention, the pulse width is 10
Since a laser beam having an edge rise width of 5 μm or less and an intensity distribution of 5 μm or less is used, the insulation resistance between the first electrode film and the second electrode film in the unit cell is more stably maintained at a high level. As a result, it becomes possible to manufacture an integrated thin-film solar cell with improved performance with a high yield.

According to the third aspect of the present invention, since visible light having a wavelength of 400 to 650 nm is used as the laser beam, damage to the first electrode film can be reduced.
The quality and characteristics of the integrated thin-film solar cell can be improved.

According to the fourth aspect of the present invention, the source of the laser beam is a YAG laser, a YVO laser, or a YL laser.
Since the F laser is used, a laser beam having a pulse width of 20 ns or less can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a manufacturing procedure of an integrated thin-film solar cell.

FIG. 2 is a graph illustrating a relationship between a pulse width of a laser beam and an insulation resistance value between electrode films.

FIG. 3 is a graph illustrating the relationship between the edge rising width of the laser beam intensity distribution and the insulation resistance between electrode films.

FIG. 4 is a conceptual diagram showing an example of a configuration of a laser beam irradiation device.

FIG. 5 is an explanatory diagram showing an intensity distribution of a laser beam, and processing and non-processing areas of a processing target.

FIG. 6 is a conceptual diagram showing an overlapping mode of a relative movement direction of a laser beam and an irradiation range.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 1st electrode film 3 Semiconductor film 4 2nd electrode film 5 Unit cell 10 Laser 11 and 21 Laser beam 20 Optical system A, B, C groove

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yasuhiro Yamauchi 1-1, Akunouramachi, Nagasaki City, Nagasaki Prefecture Mitsubishi Heavy Industries, Ltd. Nagasaki Shipyard F-term (reference) 4E068 CA03 CA04 DA09 5F051 AA05 CB28 CB29 DA04 EA10 EA11 EA16

Claims (4)

[Claims] A first electrode film, a semiconductor film, and a second electrode film on a substrate;
In the process of manufacturing an integrated thin-film solar cell in which a plurality of unit cells formed by sequentially laminating electrode films are connected in series, the laser beam and the thin film are irradiated while irradiating the thin-film solar cell with a single-pulse high-repetition rate laser beam. When providing a groove for removing the second electrode film and the semiconductor film by moving relative to the solar cell, the laser beam has a pulse width of 20 ns or less and an edge rising width of the intensity distribution of 7 μm or less. A method for producing an integrated thin-film solar cell, comprising using a laser beam. 2. The method according to claim 1, wherein the pulse width is 10 ns or less and the edge rising width is 5 μm or less. 3. The laser beam having a wavelength of 400 to 6
The method for manufacturing an integrated thin-film solar cell according to claim 1, wherein the visible light is 50 nm. 4. A laser beam generating source comprising: YA
The method for manufacturing an integrated thin-film solar cell according to any one of claims 1 to 3, wherein a G laser, a YVO laser, or a YLF laser is used.