JP7618481B2 - Solar cell panel and method for manufacturing the solar cell panel - Google Patents

Description

The present invention relates to a solar panel and a method for manufacturing a solar panel.

2. Description of the Related Art Conventionally, in solar cells, a transparent conductive oxide such as ITO is often used as a transparent electrode layer that transmits light in order to cause a photoelectric conversion substrate to absorb light (for example, Patent Document 1).
As a method for patterning a transparent conductive oxide, there is a laser scribing method using an ultraviolet laser (hereinafter also referred to as a UV laser).
In the solar cell of Patent Document 1, a YAG laser or a _YVO4 laser is used as the UV laser, and part of the transparent electrode layer is removed in a stripe shape to form grooves and perform patterning.

Recently, back-contact solar cells have been developed in which a first electrode layer and a second electrode layer serving as a counter electrode thereto are formed on the back surface of a photoelectric conversion substrate (see, for example, Patent Document 2).
The solar cell of Patent Document 2 has a photoelectric conversion substrate in which an intrinsic semiconductor layer and a p-type semiconductor layer are laminated in order in a first region on the back surface side of a semiconductor substrate, an intrinsic semiconductor layer and an n-type semiconductor layer are laminated in order in a second region on the back surface side of the semiconductor substrate, and further an intrinsic semiconductor layer and an optical adjustment layer are laminated in order on the light-receiving surface side of the semiconductor substrate.
In the solar cell of Patent Document 2, a first electrode layer composed of a transparent electrode layer and a metal electrode layer is laminated on a p-type semiconductor layer of a photoelectric conversion substrate, and a second electrode layer composed of a transparent electrode layer and a metal electrode layer is laminated on an n-type semiconductor layer.
In the solar cell of Patent Document 2, an electrode layer is formed only on the back side of the photoelectric conversion substrate, and therefore the light receiving rate can be increased compared to a double-sided electrode type solar cell in which electrode layers are formed on both sides.

JP 2016-33932 A JP 2020-155710 A

However, in the solar cell of Patent Document 2, the transparent electrode layer of the first electrode layer and the transparent electrode layer of the second electrode layer, which serves as the opposing electrode, are both provided on the back surface side, so in order to prevent a short circuit, it is necessary to precisely separate the transparent electrode layer of the first electrode layer from the transparent electrode layer of the second electrode layer.
In the solar cell of Patent Document 2, if the transparent electrode layer is patterned by a UV laser as in Patent Document 1, not only the transparent electrode layer but also a part of the semiconductor layer underlying the transparent electrode layer will be melted or damaged. Therefore, in a back-contact type solar cell as in Patent Document 2, the transparent electrode layer cannot be peeled off by a UV laser, and the transparent electrode layer is patterned by wet etching as in Patent Document 2.
As a result, in order to pattern the transparent electrode layer, processes such as forming a resist layer on the transparent electrode layer, dissolving the transparent electrode layer with a resist liquid, and peeling off the resist layer were required, resulting in problems of complexity and high manufacturing costs.

The present invention aims to provide a solar cell panel that has improved power generation efficiency compared to conventional solar cell panels, and a manufacturing method for solar cell panels that can simplify the manufacturing process compared to conventional solar cell panels.

In order to solve the above problems, the inventors investigated the laser beam to be used in the laser scribing method and discovered that by using a deep ultraviolet laser, which has a shorter wavelength than a UV laser, it is possible to remove only the transparent electrode layer and reduce the effect on the semiconductor layer that is the base of the transparent electrode layer.

One aspect of the present invention derived from this discovery is a solar cell panel including a photoelectric conversion substrate having a first texture structure on at least one of its main surfaces, and a transparent conductive oxide layer laminated on the photoelectric conversion substrate, in which, when the one of the main surfaces is viewed in plan, the solar cell panel has a covered portion in which the transparent conductive oxide layer covers the photoelectric conversion substrate, and an exposed portion in which a part of the first texture structure of the photoelectric conversion substrate is exposed from the transparent conductive oxide layer, the difference in angle between the apex of the peak of the first texture structure in the covered portion and the apex of the peak of the first texture structure in the exposed portion is within 2 degrees, and further, the transparent conductive oxide layer is thinner from the covered portion toward the exposed portion at the boundary between the covered portion and the exposed portion.

According to this aspect, the difference in angle between the apexes of the peaks of the first texture structure in the covered portion and the apexes of the peaks of the first texture structure in the exposed portion is small, so that reflection loss can be reduced even in the exposed portion, and power generation efficiency can be improved compared to conventional techniques.
According to this aspect, the transparent conductive oxide layer has a thickness that decreases from the covered portion toward the exposed portion at the boundary between the covered portion and the exposed portion, so that light can be easily guided into the photoelectric conversion substrate.

In a preferred embodiment, the transparent conductive oxide layer has an average thickness of 50 μm or more and 200 μm or less.

The preferred aspect is that the peak has an apex angle of 120 degrees or less and a pointed tip.

In a preferred embodiment, the exposed portion is groove-shaped and has a width of 0.5 mm to 1.5 mm.

In a preferred aspect, the photoelectric conversion substrate has a semiconductor layer formed on a semiconductor substrate having a second texture structure, and the semiconductor layer follows the first texture structure.

In a preferred aspect, the photoelectric conversion substrate has a first conductive type semiconductor layer and a second conductive type semiconductor layer formed adjacent to each other on the one main surface side of the semiconductor substrate, and the exposed portion is groove-shaped and is provided across the first conductive type semiconductor layer and the second conductive type semiconductor layer in the width direction.

One aspect of the present invention is a method for manufacturing a solar cell panel, comprising: a transparent conductive oxide layer formation step of forming a transparent conductive oxide layer on a photoelectric conversion substrate having a first texture structure; and a removal step of partially removing the transparent conductive oxide layer using a deep ultraviolet laser, wherein the difference in angle between apexes of peaks of the first texture structure before the removal step and the apexes of the peaks of the first texture structure in the removed portions after the removal step is within 2 degrees.
It is.

In this aspect, part of the transparent conductive oxide layer is removed using a deep ultraviolet laser, which reduces damage caused by the laser to the photoelectric conversion substrate and improves power generation efficiency compared to conventional methods.

In a preferred embodiment, the deep ultraviolet laser is a pulsed laser having a top-hat cross-sectional intensity distribution.

In a preferred aspect, the deep ultraviolet laser is the fourth harmonic of a YAG laser or a _YVO4 laser.

In the solar cell panel of the present invention, the difference in angle of the apexes of the peaks in the covered and exposed portions is small, so that the first texture structure has a high light containment effect, thereby improving power generation efficiency compared to conventional techniques.
According to the method for producing a solar cell panel of the present invention, a part of the transparent conductive oxide layer is removed by a deep ultraviolet laser, so that the production process can be simplified compared to the conventional method.

1 is a perspective view that illustrates a solar cell panel according to a first embodiment of the present invention; 2 is an explanatory diagram of the solar cell panel of FIG. 1, where (a) is a cross-sectional view of the solar cell panel, and (b) is an enlarged view of area A of (a). Note that hatching of the photoelectric conversion substrate is omitted for ease of understanding. 2A is a perspective view showing the angle of the apex of the peak of the solar cell panel of FIG. 1 , and FIG. 2B is a perspective view showing the peak of the solar cell panel of FIG. 1 in the form of a triangular pyramid. FIG. 2A is a cross-sectional view showing a transparent electrode layer formation process for forming a transparent electrode layer on a photoelectric conversion substrate; FIG. 2B is a cross-sectional view showing a laser scribing process for removing a portion of the transparent electrode layer by a laser; and FIG. 2C is a cross-sectional view showing a metal electrode layer formation process for forming a metal electrode layer on the transparent electrode layer; in order to facilitate understanding, hatching of the photoelectric conversion substrate has been omitted. 1A is a scanning electron microscope image of the boundary between the exposed portion and the coated portion of Example 1; FIG. 1B is a scanning electron microscope image of the boundary between the exposed portion and the coated portion of Example 2; and FIG. 1C is a scanning electron microscope image of the boundary between the exposed portion and the coated portion of Example 3. 1A is a scanning electron microscope image of the exposed portion of Comparative Examples 1 to 3 of the present invention, (a) is a scanning electron microscope image of the exposed portion of Comparative Example 1, (b) is a scanning electron microscope image of the exposed portion of Comparative Example 2, and (c) is a scanning electron microscope image of the exposed portion of Comparative Example 3.

The following describes an embodiment of the present invention in detail.

The solar cell panel 1 of the first embodiment of the present invention is a back-contact type solar cell panel in which a first electrode layer 3 and a second electrode layer 5 are formed on a back main surface 40 (one of the main surfaces) of a photoelectric conversion substrate 2, as shown in FIG.
The solar cell panel 1 has a first electrode layer 3 and a second electrode layer 5 arranged adjacent to each other in the width direction X, and has short-circuit prevention grooves 7, 8 extending in the length direction Y at the boundary between the first electrode layer 3 and the second electrode layer 5.

The photoelectric conversion substrate 2 has a PN junction and is a photoelectric conversion section that converts light energy into electrical energy.
As shown in Figures 1 and 2, the photoelectric conversion substrate 2 is a multilayer substrate having semiconductor layers 16, 20, 17, and 21 on the first main surface 30 side of the semiconductor substrate 10, and a light-receiving semiconductor layer 11 and an anti-reflection layer 12 on the second main surface 31 side of the semiconductor substrate 10.
That is, as shown in FIG. 1 , the photoelectric conversion substrate 2 includes a first region 35 having a cross-sectional structure in which a first intrinsic semiconductor layer 16 and a first conductivity type semiconductor layer 17 are stacked in this order on the first main surface 30 of the semiconductor substrate 10, and a second region 36 having a cross-sectional structure in which a second intrinsic semiconductor layer 20 and a second conductivity type semiconductor layer 21 are stacked in this order on the first main surface 30 of the semiconductor substrate 10.
The photoelectric conversion substrate 2 also has a light-receiving semiconductor layer 11 and an antireflection layer 12 in this order on the second main surface 31 , and the antireflection layer 12 forms the light-receiving surface of the solar cell panel 1 .

As shown in FIG. 2, the photoelectric conversion substrate 2 has a first texture structure with unevenness formed on its surface. That is, the first texture structure has a plurality of peaks 45 with pointed tips on the rear main surface 40.

The semiconductor substrate 10 is an n-type or p-type semiconductor substrate, specifically, an n-type or p-type crystalline silicon substrate. As the semiconductor substrate 10, a single crystal silicon substrate or a polycrystalline silicon substrate can be used.
2, the semiconductor substrate 10 has a second texture structure having projections and recesses formed on its surface. That is, the second texture structure has a plurality of second peaks 46 with pointed tips on the first main surface 30 side.

The first intrinsic semiconductor layer 16 is a silicon thin film that is substantially free of dopants, and the dopant concentration is preferably 1/100 or less of the dopant concentration of the first conductivity type semiconductor layer 17.

The first conductive semiconductor layer 17 is an n-type or p-type silicon-based thin film layer containing a dopant, and in this embodiment is a p-type silicon layer.

The second intrinsic semiconductor layer 20 is a silicon thin film that is substantially free of dopants, and the dopant concentration is preferably 1/100 or less of the dopant concentration of the second conductive type semiconductor layer 21.

The second conductive type semiconductor layer 21 is a silicon layer that contains a dopant and has a conductive type opposite to that of the first conductive type semiconductor layer 17 .
That is, when the conductivity type of the first conductivity type semiconductor layer 17 is n-type, the conductivity type of the second conductivity type semiconductor layer 21 is p-type, and when the conductivity type of the first conductivity type semiconductor layer 17 is p-type, the conductivity type of the second conductivity type semiconductor layer 21 is n-type.
As described above, in this embodiment, the first conductive type semiconductor layer 17 is a p-type silicon layer, and therefore the second conductive type semiconductor layer 21 is formed of an n-type semiconductor layer.

The light-receiving semiconductor layer 11 is an intrinsic silicon thin film that contains substantially no dopants.

The anti-reflection layer 12 is a low-reflection layer that has light-transmitting properties and suppresses reflection of light.
The anti-reflection layer 12 can be formed of, for example, a metal oxide such as silicon oxide, zinc oxide, or titanium oxide, or a metal nitride such as silicon nitride.
The antireflection layer 12 is preferably made of silicon nitride from the viewpoint of the optical confinement effect of incident light.

The first electrode layer 3 is paired with the second electrode layer 5 and is an electrode that, together with the second electrode layer 5 , extracts the electric energy photoelectrically converted in the photoelectric conversion substrate 2 .
As shown in Figures 1 and 2, the first electrode layer 3 is formed on the first conductivity type semiconductor layer 17 in the first region 35, and the second electrode layer 5 is formed on the second conductivity type semiconductor layer 21 in the second region 36.

As shown in FIG. 2, the electrode layers 3 and 5 are each composed of a transparent electrode layer 23 and a metal electrode layer 25 .
The transparent electrode layer 23 is a transparent conductive layer having transparency and conductivity, and specifically, is a transparent conductive oxide layer made of a transparent conductive oxide such as indium tin oxide (ITO) or tungsten-doped indium oxide (IWO).
The transparent electrode layer 23 preferably has an average film thickness of 50 μm or more and 200 μm or less.
Within this range, the resistance loss in the transparent electrode layer 23 is suppressed, and the thickness does not become too large.

The metal electrode layer 25 can be formed of metals such as gold, silver, copper, platinum, aluminum, nickel, palladium, etc., or alloys containing these metals.

The short circuit prevention grooves 7 and 8 are grooves for preventing a short circuit caused by contact between the first electrode layer 3 and the second electrode layer 5, as shown in FIG.
2, the short-circuit prevention grooves 7 and 8 are grooves that are provided across the boundary between the first conductivity type semiconductor layer 17 and the second conductivity type semiconductor layer 21 and have the first conductivity type semiconductor layer 17 and the second conductivity type semiconductor layer 21 as their bottoms. The short-circuit prevention grooves 7 and 8 extend along the boundary between the first intrinsic semiconductor layer 16 and the second conductivity type semiconductor layer 21 as shown in FIG.

Next, we will explain the relative positions of each part of the solar panel 1.

As shown in FIG. 2 , the solar cell panel 1 has, in the width direction X, a covered portion 50 in which the transparent electrode layer 23 covers the photoelectric conversion substrate 2, and an exposed portion 51 on the photoelectric conversion substrate 2 that is exposed from the transparent electrode layer 23.
The transparent electrode layer 23 has a side surface 55 in the width direction X that is an inclined surface, and the thickness becomes thinner from the covered portion 50 toward the exposed portion 51 at the boundary between the covered portion 50 and the exposed portion 51 .
In the exposed portion 51, the back main surface 40 of the photoelectric conversion substrate 2 is exposed, and the boundary portion between the first conductivity type semiconductor layer 17 and the second conductivity type semiconductor layer 21 is exposed.
The exposed portion 51 is formed by the short-circuit prevention grooves 7, 8, and is preferably groove-shaped and has a width of 0.5 mm to 1.5 mm. That is, the groove width of the short-circuit prevention grooves 7, 8 is preferably 0.5 mm to 1.5 mm.
Within this range, contact between adjacent transparent electrode layers 23 can be sufficiently prevented, and light leakage from exposed portions 51 can be suppressed.

The angle θ1 of the apex T1 of the peak 45 of the covering portion 50 is preferably equal to or greater than 95° and equal to or less than 120°.
It is preferable that the angle θ1 of the apex T1 of the peak 45 in the covered portion 50 be 1.0 to 1.9 times the angle θ2 of the apex T2 of the peak 45 in the exposed portion 51 .
The difference between the angle θ1 of the vertex T1 and the angle θ2 of the vertex T2 is preferably 0° or more and 90° or less.
The angle θ1 of the apex T1 is preferably equal to or greater than 95° and equal to or less than 120°.
The angle θ2 of the vertex T2 is smaller than the angle θ1 of the vertex T1, and is preferably equal to or greater than 95° and equal to or less than 120°.
Here, "angle θ1 of apex T1" refers to the angle of apex T1 of peak 45. For example, as shown in Fig. 3A, when peak 45 is an n-sided pyramid (a triangular pyramid in Fig. 3A), it is the angle of apex T1 in a cross section passing through a side connecting apex T1 to the base and the center of gravity of the base. Also, as shown in Fig. 3B, when peak 45 is a cone, it is the angle of apex T1 in a cross section passing through a generatrix connecting apex T1 to the base and the center of gravity of the base.
Here, "angle θ2 of apex T2" refers to the angle of apex T2 of peak 45. For example, when peak 45 is an n-sided pyramid, it is the angle of apex T2 in a cross section passing through a side connecting apex T2 and the base and the center of gravity of the base. When peak 45 is a cone, it is the angle of apex T2 in a cross section passing through a generatrix connecting apex T2 and the base and the center of gravity of the base.

The first texture structure is formed by forming semiconductor layers 16, 17, 20, and 21 on a semiconductor substrate 10, and the semiconductor layers 16, 17, 20, and 21 follow the second texture structure of the semiconductor substrate 10. That is, the peak 45 is provided at a position corresponding to the second peak 46 of the semiconductor substrate 10.

Next, a method for manufacturing the solar cell panel 1 of this embodiment will be described. Note that the manufacturing process for the photoelectric conversion substrate 2 is the same as in the conventional method, so a description thereof will be omitted.

First, as shown in FIG. 4(a), a transparent electrode layer 23 is formed on the photoelectric conversion substrate 2 using a sputtering device or the like (transparent electrode layer formation process, transparent conductive oxide layer formation process).

At this time, the transparent electrode layer 23 is formed over the entire backside main surface 40 of the photoelectric conversion substrate 2, and is formed across the first conductivity type semiconductor layer 17 and the second conductivity type semiconductor layer 21.

Next, as shown in FIG. 4(b), the transparent electrode layer 23 is partially removed by a laser beam to form short-circuit prevention grooves 7 and 8 (removal process).

The laser beam used at this time is a pulse laser having a top-hat shaped cross-sectional intensity distribution, and is a deep ultraviolet laser having a wavelength of 100 nm or more and 280 nm or less.
The laser beam in this embodiment is the fourth harmonic of a YAG laser or a _YVO4 laser, specifically, a laser with a wavelength of 266 nm.
The pulse width is preferably 60 fs or more and 10 ps or less.
The focus position is preferably 0.5 mm or more and 2 mm or less, and more preferably 0.9 mm or more and 1.5 mm or less.
At this time, the transparent electrode layer 23 is separated by the short-circuit prevention grooves 7 and 8, and laser marks sloping downward in the depth direction of the short-circuit prevention grooves 7 and 8 are formed on the side surface 55 in the width direction X.
Furthermore, the difference between the angle of the apex of the peak 45 before the removal step and the angle of the apex of the peak 45 in the exposed portion 51 (removed portion) after the removal step is within 2 degrees.

Next, the metal electrode layer 25 is formed on the transparent electrode layer 23 by screen printing or the like (metal electrode layer formation process).

At this time, it is preferable that the metal electrode layer 25 is formed only on the transparent electrode layer 23 and does not extend across the exposed portion 51.

Then, if necessary, wiring members such as interconnectors are attached to the electrode layers 3 and 5 to complete the solar panel 1.

In the solar cell panel 1 of this embodiment, an exposed portion 51 is formed at the boundary between the first electrode layer 3 and the second electrode layer 5, so that a short circuit caused by contact between the electrode layers 3 and 5 can be prevented.

According to the solar cell panel 1 of the present embodiment, the angle difference between apex T1 of peak portion 45 of the first texture structure and apex T2 of peak portion 45 is small in covered portion 50 and exposed portion 51. Therefore, reflection loss can be reduced even in exposed portion 51, and power generation efficiency can be improved compared to the conventional method.
According to the solar cell panel 1 of this embodiment, the transparent electrode layer 23 becomes thinner from the covered portion 50 toward the exposed portion 51 at the boundary between the covered portion 50 and the exposed portion 51, making it easier to guide light into the photoelectric conversion substrate 2.

According to the manufacturing method of the solar cell panel 1 of this embodiment, the short-circuit prevention grooves 7, 8 are formed by removing a portion of the transparent electrode layer 23 with a laser beam, so that the short-circuit prevention grooves 7, 8 can be formed without using a resist material.

According to the manufacturing method of the solar cell panel 1 of this embodiment, a deep ultraviolet laser having a wavelength of 100 nm or more and 280 nm or less is used as the laser beam for removing a portion of the transparent electrode layer 23, so that only the transparent electrode layer 23 can be removed in a concentrated manner, and damage to the photoelectric conversion substrate 2 can be suppressed.

In the above embodiment, the laser beam has a top-hat cross-sectional intensity distribution, but the present invention is not limited to this. The laser beam may have a Gaussian cross-sectional intensity distribution.

In the above embodiment, the photoelectric conversion substrate 2 has the intrinsic semiconductor layers 16, 20 interposed between the semiconductor substrate 10 and the conductive semiconductor layers 17, 21, but the present invention is not limited to this. The photoelectric conversion substrate 2 may have the conductive semiconductor layers 17, 21 stacked directly on the semiconductor substrate 10.

In the above embodiment, the metal electrode layer 25 is formed only on the transparent electrode layer 23, but the present invention is not limited to this. It may slightly protrude beyond the underlying transparent electrode layer 23 and straddle the semiconductor layer 17 or semiconductor layer 21 that is the underlying transparent electrode layer 23. That is, the metal electrode layer 25 with the transparent electrode layer 23 as the underlying layer on the first conductive type semiconductor layer 17 may protrude into the first conductive type semiconductor layer 17 of the exposed portion 51 as long as it is not in contact with the second conductive type semiconductor layer 21. Similarly, the metal electrode layer 25 with the transparent electrode layer 23 as the underlying layer on the second conductive type semiconductor layer 21 may protrude into the second conductive type semiconductor layer 21 of the exposed portion 51 as long as it is not in contact with the first conductive type semiconductor layer 17.

As long as the above-described embodiments fall within the technical scope of the present invention, the components may be freely substituted or added between the various embodiments.

The present invention will be specifically described below with reference to examples. Note that the present invention is not limited to the following examples, and can be modified as appropriate without departing from the gist of the present invention.

Example 1
A 6-inch n-type single crystal silicon substrate having a thickness of 200 μm and a (100) surface orientation on the incident surface was washed in acetone, then immersed in a 2 wt % aqueous hydrogen fluoride (HF) solution for 3 minutes to remove the silicon oxide film on the surface, and then rinsed with ultrapure water.
The cleaned crystalline silicon substrate was immersed in a 5/15 wt % potassium hydroxide (KOH)/isopropyl alcohol aqueous solution at 70° C. for 15 minutes, and then rinsed with ultrapure water to obtain a crystalline silicon substrate on which a pyramidal texture with the (111) plane exposed was formed.
A crystalline silicon substrate was introduced into a plasma CVD apparatus, and an intrinsic silicon layer was formed to a thickness of 8 nm under the conditions of a substrate temperature of 150° C., a pressure of 120 Pa, a H ₂ /SiH ₄ flow ratio of 10/3, and a power density of 11 mW/cm ² .
Next, a p-type silicon layer was formed on the intrinsic silicon thin film to a thickness of 2 nm under the conditions of a substrate temperature of 150° C., a pressure of 60 Pa, a flow rate ratio of B ₂ H _6- containing H ₂ /SiH ₄ of 3/1, and a power density of 11 mW/cm ^2. Note that as the B ₂ H _6- containing H ₂ , a mixed gas in which the B ₂ H ₆ concentration was diluted with H ₂ to 5000 ppm was used.
Next, a transparent conductive oxide layer with a thickness of 80 nm was formed on the peaks (tops) of the textured structure on the p-type silicon layer. Specifically, the film was formed by a sputtering method using an ITO sintered target with a tin oxide content of 10% by weight under the conditions of a substrate temperature of 150° C., argon/oxygen flow rates of 50 sccm/1 sccm, pressure of 0.2 Pa, and power density of 0.5 W/cm ² .

After forming the transparent conductive oxide layer, a laser scriber was used to perform laser scribing at 150 mm/sec with a DUV pulsed laser having a wavelength of 266 nm, a pulse width of 60 fs, and a focus position of 1.0 mm, thereby patterning the transparent conductive oxide layer and forming an exposed portion exposed from the transparent conductive oxide layer. This was designated Example 1.

Example 2
In Example 1, after the transparent conductive oxide layer was formed, laser scribing was performed three times at 150 mm/sec using a laser scriber with a DUV pulse laser having a wavelength of 266 nm, a pulse width fs, and a focus position of 1.0 mm to pattern the transparent conductive oxide layer and form an exposed portion exposed from the transparent conductive oxide layer. This was designated as Example 2.

Example 3
In Example 2, after the transparent conductive oxide layer was formed, laser scribing was performed three times at 75 mm/sec using a laser scriber with a DUV pulse laser having a wavelength of 266 nm, a pulse width of 60 fs, and a focus position of 1.0 mm to pattern the transparent conductive oxide layer and form an exposed portion exposed from the transparent conductive oxide layer. This was designated as Example 3.

(Comparative Example 1)
In Example 1, after the transparent conductive oxide layer was formed, a laser scriber was used to perform laser scribing at 300 mm/sec with a UV pulse laser having a wavelength of 355 nm, a pulse width of 60 fs, and a focus position of 0.85 mm, thereby patterning the transparent conductive oxide layer and forming an exposed portion exposed from the transparent conductive oxide layer. This was designated Comparative Example 1.

(Comparative Example 2)
In Example 2, after the transparent conductive oxide layer was formed, a laser scriber was used to perform laser scribing at 200 mm/sec with a UV pulse laser having a wavelength of 355 nm, a pulse width of 60 fs, and a focus position of 0.85 mm, thereby patterning the transparent conductive oxide layer and forming an exposed portion exposed from the transparent conductive oxide layer. This was designated Comparative Example 2.

(Comparative Example 3)
In Example 2, after the transparent conductive oxide layer was formed, a laser scriber was used to perform laser scribing at 100 mm/sec with a UV pulse laser having a wavelength of 355 nm, a pulse width of 60 fs, and a focus position of 0.85 mm, thereby patterning the transparent conductive oxide layer and forming an exposed portion exposed from the transparent conductive oxide layer. This was designated Comparative Example 3.

(Observation of surface structure)
In Examples 1 to 3 and Comparative Examples 1 to 3, the exposed portions that were laser grooves were observed using a scanning electron microscope (JSM-7610F, manufactured by JEOL Ltd.).

SEM images of Examples 1 to 3 are shown in Figure 5, and SEM images of Comparative Examples 1 to 3 are shown in Figure 6.

In the exposed areas of Comparative Examples 1 to 3 shown in Figure 6, the tips of the peaks of the textured structure that constitutes the base of the transparent conductive oxide layer were melted and rounded throughout the entire exposed area, and the textured structure was not maintained. In other words, in Comparative Examples 1 to 3, it was not possible to remove only the transparent conductive oxide layer, and part of the textured structure was dissolved and crushed as the transparent conductive oxide layer was removed.

On the other hand, in the exposed portions of Examples 1 to 3 shown in Figure 5, at least the boundary between the exposed portion and the covered portion generally maintained the texture structure, and in particular in the exposed portion of Example 1, the texture structure of the base was maintained as is throughout the entire exposed portion. In other words, in Examples 1 to 3, it was possible to remove essentially only the transparent conductive oxide layer, and as the transparent conductive oxide layer was removed, the texture structure was maintained without being dissolved at all.

From the above, it was found that in Examples 1 to 3, the textured structure of the base was maintained at the boundary between the exposed portion and the covered portion.
In particular, in Example 1, it was found that only the transparent conductive oxide layer could be removed, the texture structure in the exposed portion was not different from the texture structure in the covered portion, and the peaks of the texture structure could be maintained.

REFERENCE SIGNS LIST 1 Solar cell panel 2 Photoelectric conversion substrate 7, 8 Short circuit prevention groove 10 Semiconductor substrate 17 First conductivity type semiconductor layer 21 Second conductivity type semiconductor layer 23 Transparent electrode layer 40 Rear main surface (one of the main surfaces)
45 Mountain portion 46 Second mountain portion 50 Covering portion 51 Exposed portion (removed portion)

Claims (9)

A solar cell panel including a photoelectric conversion substrate having a first texture structure on at least one principal surface thereof, and a transparent conductive oxide layer laminated on the photoelectric conversion substrate,
When the one principal surface is viewed in plan, the photoelectric conversion substrate has a covered portion in which the transparent conductive oxide layer covers the photoelectric conversion substrate, and an exposed portion in which a part of the first texture structure of the photoelectric conversion substrate is exposed from the transparent conductive oxide layer,
a difference in angle between apexes of peaks of the first texture structure in the covered portion and apexes of peaks of the first texture structure in the exposed portion is within 2 degrees;
Furthermore, the transparent conductive oxide layer has a thickness that decreases from the covered portion toward the exposed portion at the boundary between the covered portion and the exposed portion, and a laser mark is formed on the side surface of the solar cell panel. The solar cell panel according to claim 1, wherein the transparent conductive oxide layer has an average film thickness of 50 μm or more and 200 μm or less. The solar panel according to claim 1 or 2, wherein the peaks have an apex angle of 120 degrees or less and a pointed tip. The solar cell panel according to any one of claims 1 to 3, wherein the exposed portion is groove-shaped and has a width of 0.5 mm or more and 1.5 mm or less. The solar cell panel according to any one of claims 1 to 4, wherein the photoelectric conversion substrate has a semiconductor layer formed on a semiconductor substrate having a second texture structure, and the semiconductor layer conforms to the first texture structure. The photoelectric conversion substrate includes a first conductive type semiconductor layer and a second conductive type semiconductor layer formed adjacent to each other on the one main surface side of a semiconductor substrate,
6. The solar cell panel according to claim 1, wherein the exposed portion is groove-shaped and is provided across the first conductivity type semiconductor layer and the second conductivity type semiconductor layer in the width direction. A method for producing a solar cell panel according to any one of claims 1 to 6, comprising the steps of:
a transparent conductive oxide layer forming step of forming a transparent conductive oxide layer on a photoelectric conversion substrate having a first texture structure;
a removing step of partially removing the transparent conductive oxide layer by a deep ultraviolet laser,
A method for manufacturing a solar cell panel, wherein the difference in angle between the apexes of the peaks of the first texture structure before the removal step and the apexes of the peaks of the first texture structure in the removed portion after the removal step is within 2 degrees. The method for manufacturing a solar panel according to claim 7, wherein the deep ultraviolet laser is a pulsed laser having a top-hat cross-sectional intensity distribution. 9. The method for manufacturing a solar cell panel according to claim 7 or 8, wherein the deep ultraviolet laser is a fourth harmonic of a YAG laser or a _YVO4 laser.

Images