JP2012038902A - Manufacturing method of integrated photoelectric conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an integrated photoelectric conversion device, in which a separation groove is provided for insulation between a transparent electrode layer and a rear surface electrode of a thin-film solar cell using a laser oscillator by a film surface side incidence method while suppressing a thermal effect on a base layer and a layer near a portion to be irradiated with a laser.SOLUTION: A manufacturing method of an integrated photoelectric conversion device comprises a separation groove formation step of forming a groove 12 for electrically separating at least a layer including a surface of a laminated body including a transparent electrode layer 2, a photoelectric conversion layer 3, and a rear surface electrode layer 4 that are supported by a substrate 1 by moving the substrate 1 and a laser oscillator including a focusing optical system relative to each other while intermittently performing laser irradiation with laser light with a pulse width of 1 nanosecond or less from the laser oscillator. In the separation groove formation step, the laser light irradiation is performed under a condition where the laser light has a circular cross-sectional shape and the product of the laser energy density (J/cm) and the number of times of the irradiation is 3 or more and 12 or less.

Description

  The present invention relates to a photoelectric conversion device, and more particularly to a thin film solar cell that mainly uses silicon as a power generation layer. The present invention also relates to a solar cell module and a solar cell module, and more particularly to a solar cell module and a solar cell module that perform patterning using a laser.

  As a photoelectric conversion device that receives light and converts it into electric power, for example, a thin film solar cell in which a silicon-based thin film or the like is stacked on a power generation layer (photoelectric conversion layer) is known. A thin film solar cell generally includes a cell configured by sequentially laminating a transparent electrode layer, a semiconductor layer (photoelectric conversion layer), and a back electrode layer in order from the sunlight incident side. The laminate in which the above layers are laminated is supported by the substrate.

  For the photoelectric conversion layer of the thin film solar cell, thin film silicon made of amorphous silicon (amorphous silicon) or microcrystalline silicon, CIGS (copper indium gallium selenium compound), CdTe (cadmium tellurium compound) are mainly used. A metal thin film such as silver is used for the back electrode layer of the thin film solar cell.

The structure of the thin-film solar cell can be broadly classified into a superstrate type and a substrate type from the relationship between the substrate and the incident direction of sunlight.
In the super straight type, as shown in FIG. 1, a substrate 1 made of a transparent insulator such as glass is disposed on the light incident side of the transparent electrode layer 1. The super straight type is mainly used for thin film silicon solar cells, CdTe solar cells, and the like.
In the substrate type, as shown in FIG. 8, a substrate such as stainless steel or glass is disposed on the side opposite to the light incident side (non-light incident side) of the back electrode layer. The substrate type is mainly employed in thin film silicon solar cells, CIGS solar cells and the like.

  Thin film solar cells employ an integrated module structure in which cells are connected in series to suppress power loss. In the manufacturing process, separation grooves are formed by laser scribe or mechanical scribe on the transparent electrode layer, the photoelectric conversion layer, and the back electrode layer.

In the manufacturing process of a super straight type thin film solar cell module, when forming a separation groove of a back electrode layer made of a metal thin film, a method of irradiating laser light from a light incident side through a transparent support substrate (substrate side incident method) is Often used. The energy density of the laser at this time is about 0.3 to 0.4 J / cm ² . The laser wavelength is a wavelength that has a small light absorption in the transparent electrode layer and is easily absorbed in the photoelectric conversion layer. The laser light that has been transmitted through the transparent electrode layer and absorbed by the photoelectric conversion layer is converted to heat, and the expansion force of the decomposition gas is generated in the photoelectric conversion layer. With this expansion force, the photoelectric conversion layer and the back electrode layer are removed from the interface with the transparent electrode layer, and a separation groove 102 as shown in FIG. 16 is formed.

  However, if foreign matter adheres to the transparent support substrate, the foreign matter may block the laser beam, which may hinder the formation of separation grooves in the back electrode layer. In a thin film solar battery in which no separation groove is formed in the back electrode layer and the cells are connected by the back electrode layer, a short-circuit portion is generated between the transparent electrode layer and the back electrode layer, so that power generation performance is reduced. .

  As another method of forming the separation groove of the back electrode layer, there is a method of irradiating laser light from the film surface side (non-light incident side) of the back electrode layer (film surface side incidence method). In the film side incidence method, laser light is absorbed by a metal thin film which is a back electrode layer. Since the metal thin film has a high reflectance of the laser beam, the film surface side incidence method requires a larger laser energy density than the substrate side incidence method. For this reason, the metal thin film is melted by heat generation, and the component of the photoelectric conversion layer serving as a base may be alloyed with the molten metal. In such a thin film solar cell, since the electrical resistance of the photoelectric conversion layer is lowered, there is a problem that a short circuit state occurs between the transparent electrode layer and the back electrode layer, and power generation performance is deteriorated.

As one of means for solving such a problem, there is a method of preventing short circuit by injecting ions into a photoactive layer disposed under a metal thin film for forming a separation groove to insulate. However, in order to insulate between the transparent electrode layer and the back electrode layer by ion implantation, it is necessary to control the ion implantation position.
As another means, as disclosed in Patent Document 1, when forming the separation groove in the metal thin film, an insulating portion is provided by previously removing the underlying transparent electrode layer in the overlapping portion of the laser beam. There are ways to prevent short circuits. However, with the method described in Patent Document 1, it is difficult to align the laser beam.

Japanese Patent No. 3402922

In general, a focused laser used in laser scribing by the film surface side incidence method often has a Gaussian distribution of energy in the laser cross section, and the laser peripheral portion of the Gaussian distribution has a low energy density. Therefore, when a separation groove is formed in the back electrode layer of a super-straight type thin film solar cell module using a Gaussian condensing laser, the back electrode layer cannot be completely removed or the back electrode layer or the underlying photoelectric conversion Often has a thermal effect on the layer. In particular, when there is a long short-circuited portion in the separation groove direction, the influence becomes large.
In order to avoid such a problem, a method of tilting the linear edge of the rectangular laser with respect to the moving direction of the laser using a rectangular laser in which the energy distribution of the laser cross section suddenly rises at the end is used.
However, in the above method, since a mask is used for laser shaping, the laser energy used is reduced. Further, since the imaging optical system is used, there is a problem that the depth of focus is shallow and the robustness of the processing quality against the vertical fluctuation of the substrate height is low.

  The separation groove is formed to separate the back electrode layer and insulate between the transparent electrode layer and the back electrode layer. Therefore, only the back electrode layer should be removed, but depending on the processing conditions of the separation groove, the metal thin film of the back electrode layer melts and alloyes with the silicon layer of the photoelectric conversion layer, and the photoelectric conversion layer has a low resistance. It may become. Therefore, in order to insulate between the transparent electrode layer and the back electrode layer, it is necessary to repeat the irradiation until the transparent electrode layer is exposed to form the separation groove.

When the separation groove is formed on the back electrode layer of the super straight type thin film solar cell module by the film side incidence method, if the laser energy density is too low, the photoelectric conversion layer cannot be completely removed and the transparent electrode layer is not exposed. A part arises. Further, even when the number of irradiations is reduced, the photoelectric conversion layer cannot be completely removed, and a portion where the transparent electrode layer is not exposed occurs. In the tandem-type thin film solar cell module in which the transparent electrode layer is not exposed as described above, when a DC voltage of 0.1 V is applied to a single cell having an area of 3.8 cm ² in the dark, one power generation cell is insulated. Resistance becomes 5 kΩ or less. For good module performance, 5 kΩ or more is required.

  In addition, when the laser is irradiated with the energy distribution of the Gaussian distribution using a condensing optical system without using a mask, the metal thin film does not reach evaporation at the base part of the laser light, and melts and flows into the groove. Alloying of metal and silicon is promoted. In a tandem-type thin film solar cell module having such an alloyed layer, the insulation resistance of one power generation cell is a low resistance of 1 kΩ or less.

  In the substrate type thin film solar cell module, the separation groove of the transparent electrode layer is formed by mechanical scribing from the transparent electrode layer side. The processing of the transparent electrode layer using a laser is hardly performed. Mechanical scribing is a method in which a scribing is performed by moving a needle or a substrate while pressing a needle such as diamond against the transparent electrode layer with a constant pressure. At this time, as shown in FIG. 17, the transparent electrode layer and the photoelectric conversion layer are separated and removed at the interface between the photoelectric conversion layer and the back electrode layer, thereby forming a separation groove. In this method, when the needle pressure changes due to minute protrusions on the substrate or defective discharge of shavings, when the moving speed is not appropriate, needle jumping occurs and the formation of separation grooves in the transparent electrode is interrupted, resulting in power generation performance. May be reduced.

  The present invention has been made in view of such circumstances, and when a separation groove is formed in an electrode layer of a thin film solar cell by a film surface side incidence method using a laser oscillator, the vicinity of a laser irradiated portion is provided. It is an object of the present invention to provide a method for manufacturing an integrated photoelectric conversion device in which a separation groove for insulating between a transparent electrode layer and a back electrode layer is formed while suppressing thermal influence on the layer and the base layer.

In order to solve the above-described problems, the present invention provides a laminate in which a transparent electrode layer, a photoelectric conversion layer, and a back electrode layer are stacked in order from the light incident side, either the transparent electrode layer or the back electrode layer. A method of manufacturing an integrated photoelectric conversion device supported by a substrate from one side, wherein a pulse width including a condensing optical system is provided on a surface opposite to the side of the stacked body supported by the substrate. While intermittently irradiating laser light with a laser oscillator of 1 nanosecond or less, the substrate and the laser oscillator are moved relatively to form a groove for electrically separating at least the layer including the surface. A separation groove forming step, wherein in the separation groove forming step, the cross-sectional shape of the laser beam is circular, and the product of the laser energy density (J / cm ² ) and the number of irradiations (shot) is 3 or more and 12 or less. On the condition To provide a manufacturing method of an integrated photoelectric conversion device for irradiating a serial laser beam.

According to the present invention, it is possible to prevent the occurrence of burrs that occur when irradiation is performed from the substrate surface side by irradiating laser light from the side (film surface side) opposite to the side supported by the substrate of the laminate. This makes it possible to irradiate the laser multiple times. Further, even if there is a foreign substance on the light incident surface of the substrate, the separation groove of the back electrode layer can be formed without being affected by the foreign substance.
The laser oscillator includes a condensing optical system, and the laser has a circular cross section. Since no mask imaging optical system is used, laser power loss can be suppressed, and laser power can be used effectively. In addition, since the depth of focus can be increased, it is possible to form a groove with high processing quality because it is difficult to focus on fluctuations in the height of the substrate. A laser oscillator having a pulse width of 1 nanosecond or less is used. By using a laser with a short pulse width such as a picosecond laser, the thermal effect in the vicinity of the laser irradiation can be suppressed. For example, in a super straight type silicon-based thin film solar cell, since alloying between the metal of the back electrode layer and the photoelectric conversion layer (for example, silicon) is suppressed, it is not necessary to irradiate until the transparent electrode layer is exposed, and there are few Grooves can be processed by the number of pulse irradiations.

The product of the laser energy density and the number of irradiations is 3 or more and 12 or less (J / cm ² · shot). By making the product of the laser energy density and the number of irradiations within the above range, while removing the layer to be removed including the layer to be electrically separated (such as the back electrode layer), the underlying layer and the vicinity of the laser irradiation The thermal effect of laser irradiation can be suppressed. The product of the laser energy density and the number of times of irradiation is 5 or more and 10 or less (J / cm ² · shot) in order to obtain processing conditions with high robustness in consideration of fluctuations in the thickness of the layer to be removed. It is preferable that

When the photoelectric conversion layer includes a crystalline silicon p layer, a crystalline silicon i layer, and a silicon n layer, the layer on the laser irradiated surface side of the crystalline silicon i layer is removed in the separation groove forming step. It is preferable to form a groove so that the crystalline silicon i layer is exposed.
The crystalline silicon i layer is a layer having a lower conductivity than the crystalline silicon p layer and the silicon n layer. Therefore, by forming the groove so that the crystalline silicon i layer is exposed, a high insulation resistance between the transparent electrode layer and the back electrode layer can be obtained while completely separating the layer to be electrically separated. . “The crystalline silicon i layer is exposed” means that the bottom surface of the groove is substantially composed of the crystalline silicon i layer, and the crystalline silicon i layer is partly removed in the film thickness direction. It may be in a state of being thinner than the film thickness.

When the photoelectric conversion layer includes a compound semiconductor n layer and a compound semiconductor p layer, in the separation groove forming step, the layer on the laser irradiated surface side of the compound semiconductor p layer is removed, and the compound semiconductor p layer It is preferable to form a groove so that is exposed.
When a compound semiconductor is used for the photoelectric conversion layer, the compound semiconductor n layer is a window layer and the compound semiconductor p layer is a main light absorption layer. Therefore, by forming the groove so that the compound semiconductor p layer is exposed, a high insulation resistance between the transparent electrode layer and the back electrode layer can be obtained while completely separating the layer to be electrically separated. “The compound semiconductor p layer is exposed” means that the bottom surface of the groove is substantially composed of the compound semiconductor p layer, and the compound semiconductor p layer is partially removed in the film thickness direction from the initial film thickness. May be in a thinned state.

On the condition that the product of the laser energy density (J / cm ² ) and the number of irradiation times (shot) is 3 or more and 12 or less, and the insulation resistance between the transparent electrode layer and the back electrode layer is 5 kΩ or more. You may irradiate the said laser beam.

  According to the present invention, the product of the laser energy density and the number of times of irradiation is determined, and the laser irradiation is performed under the conditions within the range, thereby suppressing the thermal influence on the layer near the laser irradiated portion and the underlying layer, and transparent. A separation groove that insulates between the electrode layer and the back electrode layer can be formed. The above method can be used as an alternative method of mechanical scribing in forming a separation groove of a transparent electrode layer of a substrate type thin film solar cell. Further, the method for manufacturing an integrated photoelectric conversion device according to the present invention can be used for repairing a defective portion of groove separation caused by a mechanical scribe method.

It is the schematic showing the structure of the integrated photoelectric conversion apparatus manufactured by the manufacturing method of the integrated photoelectric conversion apparatus which concerns on 1st Embodiment. It is the schematic which shows the manufacturing method of the solar cell panel of this embodiment. It is the schematic which shows the manufacturing method of the solar cell panel of this embodiment. It is a figure explaining the frequency | count of irradiation. It is the schematic which shows the manufacturing method of the solar cell panel of this embodiment. It is the schematic which shows the manufacturing method of the solar cell panel of this embodiment. It is the schematic which shows the manufacturing method of the solar cell panel of this embodiment. It is the schematic showing the structure of the integrated photoelectric conversion apparatus manufactured by the manufacturing method of the integrated photoelectric conversion apparatus which concerns on 2nd Embodiment. It is the schematic of the substrate type thin film solar cell module which concerns on this embodiment. 1 is a schematic view of a super straight type thin film solar cell module manufactured in Example 1. FIG. It is a figure which shows the relationship between the pulse width of the laser oscillator in Example 1, and insulation resistance. It is a figure which shows the relationship between the frequency | count of irradiation, and a laser energy density. It is a figure which shows the relationship between the product of a laser energy density and the frequency | count of irradiation, and insulation resistance. It is the photograph which observed the thin film solar cell module after processing a separation groove from the film surface side. It is the photograph which observed the thin film solar cell module after processing a separation groove from the film surface side. It is sectional drawing of the super straight type thin film solar cell module produced by the conventional method. It is sectional drawing of the substrate type thin film solar cell module produced by the conventional method.

Hereinafter, an embodiment of a method for manufacturing an integrated photoelectric conversion device according to the present invention will be described with reference to the drawings.
<First Embodiment>
FIG. 1 is a schematic diagram illustrating a configuration of an integrated photoelectric conversion device manufactured by the method for manufacturing an integrated photoelectric conversion device according to the first embodiment. The photoelectric conversion device 100 is a super straight type tandem silicon solar cell, and includes a substrate 1, a transparent electrode layer 2, a first cell layer 91 (amorphous silicon system) as a solar cell photoelectric conversion layer 3, and a second one. A cell layer 92 (crystalline silicon), an intermediate contact layer 5, and a back electrode layer 4 are provided. Here, the silicon-based is a generic name including silicon (Si), silicon carbide (SiC), and silicon germanium (SiGe). Further, the crystalline silicon system means a silicon system other than the amorphous silicon system, and includes microcrystalline silicon and polycrystalline silicon.

  A method for manufacturing a photoelectric conversion device according to the first embodiment will be described by taking a process for manufacturing a solar cell panel as an example. 2, FIG. 3, FIG. 5 and FIG. 6 are schematic views showing a method for manufacturing a solar cell panel of the present embodiment.

(1) FIG. 2 (a)
As the substrate 1, a large soda float glass substrate (for example, 1.4 m × 1.1 m × plate thickness: 3.0 mm to 4.5 mm) having an area exceeding 1 m ² is used. The end face of the substrate is preferably subjected to corner chamfering or R chamfering to prevent damage due to thermal stress or impact.

(2) FIG. 2 (b)
As the transparent electrode layer 2, a transparent conductive film having a thickness of about 500 nm to 800 nm and having tin oxide (SnO ₂ ) as a main component is formed at about 500 ° C. with a thermal CVD apparatus. At this time, a texture with appropriate irregularities is formed on the surface of the transparent electrode film. Further, the transparent electrode layer 2 may be a transparent conductive film having a thickness of about 200 nm to 900 nm mainly composed of a zinc oxide film (ZnO). As the transparent electrode layer 2, an alkali barrier film (not shown) may be formed between the substrate 1 and the transparent electrode film in addition to the transparent electrode film. As the alkali barrier film, a silicon oxide film (SiO ₂ ) is formed at a temperature of about 500 ° C. in a thermal CVD apparatus at 50 nm to 150 nm.

(3) FIG. 2 (c)
Thereafter, in order to form a separation groove in the transparent electrode layer 2, the substrate 1 is placed on an XY table, and the first harmonic (1064 nm) of the YAG laser is applied to the transparent electrode film as indicated by the arrow in the figure. Irradiate from the film surface side. The laser power is adjusted so as to be suitable for the processing speed, and the transparent electrode film is moved relative to the direction perpendicular to the series connection direction of the power generation cells 7 to move the substrate 1 and the laser beam to form the groove 10. Thus, laser etching is performed in a strip shape having a predetermined width of about 6 mm to 15 mm. Note that the direction of laser light irradiation may be performed from the substrate 1 side.

(4) FIG. 2 (d)
As the first cell layer 91, a p layer, an i layer, and an n layer made of an amorphous silicon thin film are formed by a plasma CVD apparatus. Using SiH ₄ gas and H ₂ gas as main raw materials, the amorphous silicon p layer 31 from the side on which sunlight is incident on the transparent electrode layer 2 at a reduced pressure atmosphere: 30 Pa to 1000 Pa and a substrate temperature: about 200 ° C. Then, an amorphous silicon i layer 32 and an amorphous silicon n layer 33 are formed in this order. The amorphous silicon p layer 31 is mainly made of amorphous B-doped silicon and has a thickness of 10 nm to 30 nm. The amorphous silicon i layer 32 has a thickness of 200 nm to 350 nm. The amorphous silicon n layer 33 is mainly P-doped silicon containing microcrystalline silicon in amorphous silicon, and has a thickness of 30 nm to 50 nm. A buffer layer may be provided between the amorphous silicon p layer 31 and the amorphous silicon i layer 32 in order to improve interface characteristics.

  Next, a crystalline material as the second cell layer 92 is formed on the first cell layer 91 by a plasma CVD apparatus at a reduced pressure atmosphere: 3000 Pa or less, a substrate temperature: about 200 ° C., and a plasma generation frequency: 40 MHz or more and 100 MHz or less. A silicon p layer 41, a crystalline silicon i layer 42, and a crystalline silicon n layer 43 are sequentially formed. The crystalline silicon p layer 41 is mainly made of B-doped microcrystalline silicon and has a thickness of 10 nm to 50 nm. The crystalline silicon i layer 42 is mainly made of microcrystalline silicon and has a film thickness of 1.2 μm or more and 3.0 μm or less. The crystalline silicon n layer 43 is mainly made of P-doped microcrystalline silicon and has a thickness of 20 nm to 50 nm. The crystalline silicon n layer may be replaced with an amorphous silicon n layer.

  In forming the i-layer film mainly composed of microcrystalline silicon by the plasma CVD method, the distance d between the plasma discharge electrode and the surface of the substrate 1 is preferably 3 mm or more and 10 mm or less. If it is smaller than 3 mm, it is difficult to keep the distance d constant from the accuracy of each component device in the film forming chamber corresponding to the large substrate, and there is a possibility that the discharge becomes unstable because it is too close. When it is larger than 10 mm, it is difficult to obtain a sufficient film forming speed (1 nm / s or more), and the uniformity of the plasma is lowered and the film quality is lowered by ion bombardment.

  An intermediate contact layer 5 serving as a semi-reflective film is provided between the first cell layer 91 and the second cell layer 92 in order to improve the contact property and achieve current matching. As the intermediate contact layer 5, a ZnO film doped with Ga or Al having a film thickness of 20 nm to 100 nm is formed by sputtering using a target: Ga-doped ZnO sintered body or Al-doped ZnO sintered body. Further, the intermediate contact layer 5 may not be provided.

(5) FIG. 2 (e)
The substrate 1 is placed on an XY table, and the second harmonic (532 nm) light of the laser diode pumped YAG laser is irradiated to the photoelectric conversion layer 3 as shown by the arrows in the figure to form separation grooves. Pulse oscillation: 10 kHz to 20 kHz, laser power is adjusted so as to be suitable for the processing speed, and laser etching is performed so that grooves 11 are formed on the lateral side of the laser etching line of the transparent electrode layer 2 from about 100 μm to 150 μm. To do. This separation groove is an open groove for obtaining an electrical connection between the transparent electrode layer 2 and the back electrode layer 4 to be formed later. Although the laser irradiation direction at this time may be performed from the film surface side of the photoelectric conversion layer 3, a large number of irradiations are required because the film thickness is large. On the other hand, when irradiation is performed from the substrate 1 side, the film can be removed with a small number of irradiations of 1 to 2 shots. In this case, since the photoelectric conversion layer 3 can be etched using the high vapor pressure generated by the energy absorbed by the amorphous silicon-based first cell layer 91 of the photoelectric conversion layer 3, further stable laser etching processing can be performed. Can be done. At this time, even if there is a foreign substance on the substrate 1 side and the laser beam is blocked and the separation groove is partially interrupted, the contact resistance between the transparent electrode layer 2 and the back electrode layer 4 is almost affected. It doesn't matter because it doesn't give. The position of the laser etching line is selected in consideration of positioning tolerances so as not to intersect with the etching line in the previous process.

(6) FIG. 3 (a)
An Ag film / Ti film is formed as the back electrode layer 4 by a sputtering apparatus at a reduced pressure atmosphere and at a film forming temperature of 150 ° C. to 200 ° C. In this embodiment, an Ag film: 150 nm or more and 500 nm or less, and a Ti film having a high anticorrosion effect: 10 nm or more and 20 nm or less are stacked in this order to protect them. Alternatively, the back electrode layer 4 may have a laminated structure of an Ag film having a thickness of 25 nm to 100 nm and an Al film having a thickness of 15 nm to 500 nm. In addition, in the case where a long wavelength side reflected light of 600 nm or more is required, such as a tandem solar cell, a laminated structure of a Cu film having a thickness of about 100 nm to 450 nm and a Ti film having a thickness of about 5 nm to 150 nm It is also good. Further, the back electrode layer 4 may be an Ag film or Al film having a thickness of 150 nm to 500 nm.
For the purpose of reducing the contact resistance between the n layer 43 and the back electrode layer 4 and improving the light reflection, Ga or Al having a film thickness of 50 nm or more and 100 nm or less is formed between the photoelectric conversion layer 3 and the back electrode layer 4 by a sputtering apparatus. Alternatively, a ZnO film doped with may be formed.

(7) FIG. 3 (b)
The substrate 1 is placed on an XY table, and the laser beam is irradiated from the film surface side of the back electrode layer 4 while irradiating laser light as shown by the arrows in the figure, and the substrate is moved to separate the grooves on the back electrode layer 4. Processing. Laser etching is performed so that the separation groove 12 is formed on the lateral side of the transparent electrode layer 2 from 250 μm to 400 μm of the laser etching line.

  The operating wavelength of the laser is appropriately selected within the range of 266 to 1064 nm. For example, the second harmonic (wavelength 532 nm) is advantageous in terms of laser output stability and cost. Further, when copper is used for the back electrode layer 4, it is easy to absorb light with a short wavelength (355 nm or less), and therefore a third harmonic (wavelength 355 nm) or fourth harmonic (wavelength 266 nm) laser is advantageous for processing. is there.

  As the laser oscillator, a YAG laser nanosecond laser, picosecond laser, or femtosecond laser having a single mode oscillation is used. When the separation groove 12 is formed, a laser beam having a circular cross section is irradiated using a condensing optical system without using a mask. The laser beam is condensed to be narrower than the groove width of the separation groove 12. Specifically, the laser beam is focused to about 20 to 60 μm.

The laser energy density is appropriately set so that the product of the laser energy density and the number of irradiations is in the range of 3 to 12 (J / cm ² · shot).
The number of times of laser light irradiation is preferably 5 times or less, and more preferably 3 to 4 times. As shown in FIG. 4, the number of times of irradiation means the number of times of irradiation to the same location due to overlapping of lasers. Two or more irradiations are required to form a continuous groove. The number of times of irradiation is represented by (processing mark length at the time of one irradiation) / (movement width of substrate or laser for each pulse). The processing mark length means the diameter of the cross section of one focused laser beam.
The oscillation frequency is 5 kHz to 200 kHz. The moving speed of the substrate or laser is 50 mm / s to 2000 mm / s. For example, if the laser oscillation frequency is 80 kHz, the movement speed of the substrate is 800 mm / s, the movement width of the substrate per pulse is 10 μm, and the diameter of the machining trace is 30 μm. For example, if the laser oscillation frequency is 10 kHz, the substrate moving speed is 50 mm / s, the substrate moving width per pulse is 5 μm, and the diameter of the processing mark is 20 μm. Adjust as appropriate.

  As shown in FIG. 3B, the crystalline silicon n layer 43 of the back electrode layer 4 and the second cell layer 92 having a high conductivity is removed, and the crystalline silicon i layer 42 having a relatively low conductivity is exposed. The separation groove 12 may be formed as described above.

(8) FIG. 3 (c) and FIG. 5 (a)
The power generation region is divided, and the film edge around the substrate edge is laser-etched to prevent a short circuit at the serial connection portion. That is, in order to ensure the insulation performance of the panel, insulation processing is performed on the peripheral edge of the substrate. The substrate 1 is placed on an XY table, and the second harmonic (532 nm) of the laser diode pumped YAG laser is irradiated from the substrate 1 side. The laser light is absorbed by the transparent electrode layer 2 and the photoelectric conversion layer 3, and the back electrode layer 4 explodes using the high gas vapor pressure generated at this time, and the back electrode layer 4 / photoelectric conversion layer 3 / transparent electrode layer 2 is removed. Pulse oscillation: 1 kHz or more and 50 kHz or less, the laser power is adjusted so as to be suitable for the processing speed, and the position of 5 mm to 20 mm from the end of the substrate 1 is placed in the X-direction insulating groove as shown in FIG. Laser etching is performed to form 15. In addition, in FIG.3 (c), since it becomes X direction sectional drawing cut | disconnected in the direction in which the photoelectric converting layer 3 was connected in series, the back surface electrode layer 4 / photoelectric conversion is originally in the position of the insulating groove 15 Although there should be a state (see FIG. 5A) corresponding to the peripheral film removal region 14 where the layer 3 / transparent electrode layer 2 has been polished and removed, description of processing to the end of the substrate 1 For the sake of convenience, the insulating groove formed to represent the Y-direction cross section at this position will be described as the X-direction insulating groove 15. At this time, the Y-direction insulating groove does not need to be provided because the film surface polishing removal processing of the peripheral film removal region of the substrate 1 is performed in a later process.

  The insulating groove 15 has an effective effect in suppressing moisture permeation from the outside into the solar cell module 6 from the end of the solar cell panel by terminating the etching at a position of 5 mm to 15 mm from the end of the substrate 1. This is preferable.

  In addition, although the laser beam in the above process is made into a YAG laser, there exists what can use a YVO4 laser, a fiber laser, etc. similarly.

(9) FIG. 5 (a: view seen from the solar cell film side, b: view seen from the substrate side of the light receiving surface)
Since the laminated film around the substrate 1 (peripheral film removal region 14) has a step and is easy to peel off in order to ensure a sound adhesion / seal surface with the back sheet 24 via EVA or the like in a later process, The film is removed to form a peripheral film removal region 14. In removing the film over the entire circumference of the substrate 1 at 5 to 20 mm from the end of the substrate 1, the X direction is closer to the substrate end than the insulating groove 15 provided in the step of FIG. The back electrode layer 4 / photoelectric conversion layer 3 / transparent electrode layer 2 are removed by using grinding stone polishing, blast polishing, or the like on the substrate end side with respect to the groove 10 near the side portion.
Polishing debris and abrasive grains are removed by cleaning the substrate 1.

(10) FIGS. 6 (a) and 6 (b)
A solar cell is obtained by collecting current from the back electrode layer 4 of the power generation cell 7 at one end and the back electrode layer 4 of the current collecting cell connected to the power generation cell 7 at the other end using a copper foil. It processes so that electric power can be taken out from the part of the terminal box 23 of a panel back side. In order to prevent short circuit with each part, the copper foil for current collection arrange | positions an insulating sheet wider than copper foil width.
After the current collecting copper foil or the like is disposed at a predetermined position, an adhesive filler sheet made of EVA (ethylene vinyl acetate copolymer) or the like is disposed so as to cover the entire solar cell module 6 and not protrude from the substrate 1. .
A back sheet 24 having a high waterproofing effect is installed on the adhesive filler sheet. In this embodiment, the back sheet 24 has a three-layer structure of PET sheet / Al foil / PET sheet so that the waterproof and moisture-proof effect is high.
An opening through window is provided at the attachment portion of the terminal box 23 of the back sheet 24 to take out the copper foil for current collection. In the opening through window portion, an insulating material is provided in a plurality of layers between the back sheet 24 and the back electrode layer 4 to suppress intrusion of moisture and the like from the outside.
The one with the back sheet 24 in place is degassed in a reduced pressure atmosphere with a laminator and pressed at about 150 to 160 ° C., and the adhesive filler sheet (EVA) is cross-linked and tightly sealed. Process.
The adhesive filler sheet is not limited to EVA, and an adhesive filler having a similar function such as PVB (polyvinyl butyral) can be used. In this case, the processing is performed by optimizing the conditions such as the pressure bonding procedure, temperature and time.

(11) FIG. 6 (a)
The terminal box 23 is attached to the back side of the solar cell module 6 with an adhesive.
(12) FIG. 6 (b)
The copper foil and the output cable of the terminal box 23 are connected by solder or the like, and the inside of the terminal box 23 is filled with a sealing agent (potting agent) and sealed. Thus, the solar cell panel 50 is completed.
(13) FIG. 6 (c)
A power generation inspection and a predetermined performance test are performed on the solar cell panel 50 formed in the steps up to FIG. The power generation inspection is performed using a solar simulator of AM 1.5 and global solar radiation standard sunlight (1000 W / m 2). The power generation inspection may be performed after the solar battery panel 50 is completely completed, or may be performed before the aluminum frame frame is attached.
(14) FIG. 6 (d)
Before and after the power generation inspection (FIG. 6C), a predetermined performance inspection is performed including an appearance inspection.

(15) FIG.
An aluminum frame frame that adds strength to the solar cell module 6 and serves as a mounting seat is attached around the solar cell module 6. It is preferable to securely hold the solar cell module 6 and the aluminum frame frames 103L and 103S through rubber gaskets or the like while maintaining elasticity.
Thus, the solar cell panel 50 is completed.

Second Embodiment
FIG. 8 is a schematic diagram illustrating a configuration of an integrated photoelectric conversion apparatus 200 manufactured by the integrated photoelectric conversion apparatus manufacturing method according to the second embodiment. The photoelectric conversion device 200 is a substrate-type tandem silicon solar cell, and the first cell layer 91 (amorphous silicon) as the transparent electrode layer 2 and the solar cell photoelectric conversion layer 3 in this order from the sunlight incident side. System) and a second cell layer 92 (crystalline silicon system), an intermediate contact layer 5, and a back electrode layer 4. The laminate in which the above layers are laminated is supported by the substrate 21 from the back electrode layer side.

  As the substrate 21, a non-translucent substrate made of stainless steel or polyimide, or a glass substrate similar to that of the first embodiment is used.

  On the substrate 21, the back electrode layer 4, the intermediate contact layer 5, the second cell layer 92, the first cell layer 91, and the transparent electrode layer 2 are formed in this order. The first embodiment is followed except for the step of forming the separation groove 22.

  FIG. 9 shows a schematic diagram of a substrate-type thin film solar cell module according to the present embodiment. FIG. 9A is a front view, and FIG. 9B is a cross-sectional view. In this embodiment, after forming the transparent electrode layer 2, as indicated by the arrow, while irradiating the transparent electrode layer 2 with a pulse from the side opposite to the side of the transparent electrode layer 2 supported by the substrate (film surface side), , Move the substrate relative to each other. In this embodiment, the crystalline silicon p layer 43 having a high conductivity of the transparent electrode layer 2, the first cell layer 91, and the second cell layer 92 is removed, and the crystalline silicon i layer 42 having a relatively low conductivity is exposed. The separation groove 22 is preferably formed so as to do so. The laser light irradiation conditions are the same as those in the first embodiment. As a result, a thin-film solar battery module in which a plurality of power generation cells 7 are electrically connected in series via the module connection portion 80 as shown in FIG.

  In 1st Embodiment and 2nd Embodiment, although the tandem-type solar cell was demonstrated as a solar cell, this invention is not limited to this example. For example, the present invention can be similarly applied to a single-layer amorphous silicon thin film solar cell.

<Third Embodiment>
The integrated photoelectric conversion device manufactured by the integrated photoelectric conversion device manufacturing method according to the third embodiment is a super straight type thin film solar cell using a compound semiconductor film as a photoelectric conversion layer. The integrated photoelectric conversion device according to the present embodiment corresponds to the transparent electrode layer and the window layer as the solar cell photoelectric conversion layer in order from the sunlight incident side on the substrate (corresponding to the first cell layer 91 of the first embodiment). ), A main light absorption layer (corresponding to the second cell layer 92 of the first embodiment), and a back electrode layer.

As the substrate, a translucent substrate is used as in the first embodiment.
The transparent electrode layer is an Al-doped ZnO film having a thickness of about 150 nm to 900 nm.
The window layer is an n-type CdS film, an n-type ZnO / CdS film, an n-type ZnMgO film, or an n-type ZnSOH film having a thickness of about 20 nm to 150 nm.
The main light absorption layers are p-type CIGS, p-type CZTS (copper, zinc, tin, sulfur-based chalcopyrite), and p-type CdTe films. The thickness of the main light absorption layer is about 1 μm to 3 μm.
The back electrode layer is a metal thin film such as molybdenum (Mo) having a thickness of about 150 nm to 500 nm.

  In this embodiment, as in the first embodiment, the substrate is relatively moved while irradiating laser light from the film surface side of the back electrode layer, the back electrode layer is removed, and the main light absorption layer is exposed. Alternatively, it is preferable to form a groove halfway through the main light absorption layer.

<Fourth embodiment>
The integrated photoelectric conversion device manufactured by the integrated photoelectric conversion device manufacturing method according to the fourth embodiment is a substrate-type thin film solar cell using a compound semiconductor film as a photoelectric conversion layer. The integrated photoelectric conversion device according to this embodiment includes a transparent electrode layer, a window layer as a solar cell photoelectric conversion layer (corresponding to the first cell layer 91 of the first embodiment), and main light sequentially from the sunlight incident side. An absorption layer (corresponding to the second cell layer 92 of the first embodiment) and a back electrode layer are provided. The laminate in which the above layers are laminated is supported by the substrate from the back electrode layer side.

As in the second embodiment, a transparent substrate such as glass or a non-transparent substrate such as stainless steel is used as the substrate.
The transparent electrode layer, the window layer, the main light absorption layer, and the back electrode layer are the same as those in the third embodiment.

  In the present embodiment, as in the second embodiment, the substrate is relatively moved while irradiating laser light from the film surface side of the transparent electrode layer, the transparent electrode layer and the window layer are removed, and the main light absorption layer is A groove may be formed so as to be exposed or partway in the main light absorption layer.

Below, the Example of the manufacturing method of the photoelectric conversion apparatus which concerns on this embodiment is described.
Example 1
Using a glass substrate 1 (5 cm × 5 cm × plate thickness: 4 mm), a super straight tandem thin film solar cell module as shown in FIG. 1 was produced.
Transparent electrode layer 2: tin oxide film, average film thickness 800 nm
Amorphous silicon p-layer 31: average film thickness 10 nm
Amorphous silicon i layer 32: Average film thickness 300 nm
Amorphous silicon n layer 33: Average film thickness 40 nm
Crystalline silicon p layer 41: Average film thickness 20 nm
Crystalline silicon i layer 42: film thickness of 1.9 to 2.9 μm
Crystalline silicon n layer 43: Average film thickness 50 nm
Back electrode layer 4: Ag film / average film thickness 250 nm

Until the back electrode layer 4 was laminated, it was fabricated in the same process as in the first embodiment. The separation groove 12 of the back electrode layer 4 is formed by using a laser oscillator as a pulse width: 100 nsec, 10 nsec, 1 (0.9 to 1.3) nsec, 15 p (pico) sec, 300 f (femto) sec. A single mode laser was used. The laser light irradiation conditions were a wavelength of 532 nm, an oscillation frequency of 5 kHz to 100 kHz, and a substrate moving speed of 50 mm / second to 800 mm / second. A laser beam condensed so as to be a circle having a laser diameter of 20 μm to 60 μm was irradiated from the film surface side of the back electrode layer 4. The energy distribution of the laser beam cross section remained a Gaussian distribution, and processing was performed without performing beam shaping with a mask. FIG. 10 shows a schematic diagram of a super straight type thin film solar cell module manufactured in Example 1. FIG. FIG. 10A is a front view, and FIG. 10B is a cross-sectional view. In addition, FIG. 10 is a figure for demonstrating the structure of the thin film solar cell module produced above, and does not reflect the magnitude | size correctly. The back electrode layer 4 and the crystalline silicon n layer 43 were removed, and irradiation was repeated until the crystalline silicon i layer 42 was exposed to form the separation grooves 12. As a result, a thin-film solar cell module in which the power generation cells 7 were electrically connected in series via the module connection portion 80 as shown in FIG. 10 was produced. In Example 1, the area of one power generation cell 7 was 3.8 cm ² .

Using the tandem-type thin film solar cell module produced above, a direct current voltage of 0.1 V is applied between the transparent electrode layer 2 and the back electrode layer 4 in the dark for 3 seconds to obtain the insulation resistance of one power generation cell. It measured with the insulation tester.
FIG. 11 is a diagram showing the relationship between the pulse width of the laser oscillator and the insulation resistance. In the figure, the horizontal axis represents the pulse width (seconds), and the vertical axis represents the insulation resistance, which indicates the maximum value of the insulation resistance between the transparent electrode layer 2 and the back electrode layer 4 in one power generation cell 7. According to FIG. 11, high insulation resistance was obtained with a pulse width of 1 nsec or less. In the range where the pulse width was lower than 1 nsec, there was no significant difference in the insulation resistance value even if the pulse width was n sec, p sec and f sec. This means that there is little leakage (shunt) current path between the transparent electrode layer 2 and the back electrode layer 4 and the insulation is made up to the inherent resistance of the cell.

As a result of a separate test, the power generation performance of the tandem-type thin film solar cell module produced in Example 1 has an IV curve shape factor (FF) of 0.68 to 0.70, and a high value is obtained with good reproducibility. It was confirmed. This means that the thermal influence on the base during the processing of the separation groove 12 is suppressed, and the quality of the film serving as the base is very little.
From the above, it was found that the pulse width of the laser oscillator is preferably 1 nsec or less. Table 1 shows the laser processing conditions at this time.

  Next, the back electrode layer 4 and the crystalline silicon n-layer 43 are removed under the following irradiation conditions, and irradiation is repeated until the crystalline silicon i-layer 42 is exposed to form the separation groove 12. A battery module was produced.

  FIG. 12 shows the relationship between the number of laser irradiations required to form the separation groove 12 and the laser energy density. In the figure, the horizontal axis represents the number of irradiations and the vertical axis represents the laser energy density. The Δ plot shows a case where the irradiation energy is set high, and the back metal film having a high reflectance can be easily removed, but the surplus energy tends to have a thermal effect on the ground. On the other hand, the ▪ plot is the minimum energy condition for removing the back electrode and exposing the crystalline silicon i layer to form a separation groove. According to FIG. 12, if the number of times of irradiation is large, the separation groove 12 can be processed even with a low laser energy density. However, as the number of times of irradiation increases, the processing time increases accordingly. Even when a laser with a short pulse width is used, if the number of times of laser irradiation is large, the thermal effect on the base film increases. Therefore, it is better that the number of times of irradiation is small. Specifically, the number of times of irradiation is 5 shots or less, preferably 2 to 4 shots. In addition, the inventors of FIG. 12 indicate that the region between the transparent electrode layer 2 and the back electrode layer 4 is below the curve connecting the Δ plots and above the curve connecting the ■ plots. It has been found that the insulation resistance is 5 kΩ or more.

Using the tandem-type thin film solar cell module, the laser energy density is 1.3 to 5 J / cm ² , the number of irradiations is 2 to 6 shots, and between the transparent electrode layer 2 and the back electrode layer 4, 0. A DC voltage of 1 V was applied for 3 seconds in the dark, and the insulation resistance of one power generation cell 7 was measured with an insulation tester.
FIG. 13 shows the relationship between the product of the laser energy density and the number of irradiations and the insulation resistance. In the figure, the horizontal axis represents the product of the laser energy density and the number of irradiations, and the vertical axis represents the insulation resistance. In FIG. 13, if the product of the laser energy density and the number of irradiations is 3 or more and 12 or less (J / cm ² · shot), the insulation resistance between the transparent electrode layer 2 and the back electrode layer 4 is 5 kΩ or more. It was. When the product of the laser energy density and the number of irradiations is 3 (J / cm ² · shot) or less, the back electrode layer 4 may not be removed. When the product of the laser energy density and the number of irradiations is 12 (J / cm ² · shot) or more, the rest of the i-layer film becomes thin depending on the film thickness of the crystalline silicon i-layer 42, When B (boron) contained in the P layer diffuses into the i layer film, the resistance of the i layer film decreases, and the insulation resistance of the cell tends to decrease.

FIG. 14 and FIG. 15 show photographs of the thin film solar cell module after processing the separation groove 12 observed from the film surface side.
FIG. 14 is a photograph when a laser having a pulse width of 300 fs is used and irradiated twice from the film surface side of the back electrode layer 4 at a laser energy density of 2.9 (J / cm ² ).
FIG. 15 is a photograph when a laser having a pulse width of 300 fsec is used and irradiated with the laser energy density of 1.9 (J / cm ² ) four times from the film surface side of the back electrode layer 4.
In FIG. 14, the crystalline silicon i layer 42 is exposed, but the back electrode layer 4 and the crystalline silicon n layer 43 are not completely removed. On the other hand, in FIG. 15, the portion where the crystalline silicon i layer 42 is exposed is formed as a continuous groove.

Considering the above results and film thickness fluctuations of the back electrode layer 4 and the crystalline silicon i layer 42, the product of the laser energy density and the number of irradiation times is 5 to 10 (J / cm ² · shot) as a processing condition with high robustness. ) Is desirable.

(Example 2)
Using a stainless steel substrate (thickness: 200 μm), a substrate type tandem thin film solar cell module as shown in FIG. 8 was produced.
Transparent electrode layer 2: zinc oxide film, average film thickness 600 nm
Amorphous silicon p-layer 31: average film thickness 20 nm
Amorphous silicon i layer 32: Average film thickness 280 nm
Amorphous silicon n layer 33: Average film thickness 50 nm
Crystalline silicon p layer 41: Average film thickness 20 nm
Crystalline silicon i layer 42: film thickness of 1.9 to 2.9 μm
Crystalline silicon n layer 43: Average film thickness 50 nm
Back electrode layer 4: Al film / average film thickness 250 nm

The laser oscillator used and the irradiation conditions of the laser light were the same as those in Example 1. In this example, a laser having a circular cross-sectional shape was irradiated from a film surface side of the transparent electrode layer 2 using a condensing optical system, and the substrate was moved to process the separation groove of the back electrode layer 4. The area of one power generation cell 7 was 3.8 cm ² .

In the same manner as in Example 1, the insulation resistance between the transparent electrode layer 2 and the back electrode layer 4 was measured using the tandem-type thin film solar cell module produced above. As a result, the insulation resistance between the transparent electrode layer and the back electrode layer of one power generation cell of the substrate type tandem thin film solar cell module was almost the same as that shown in FIG.
Since the transparent electrode film is sublimable and transmits visible light, it is removed together with the amorphous silicon when it is absorbed by the first cell layer (amorphous silicon layer). In the case of the substrate type, since there is no opaque metal thin film, the transparent electrode film is easily removed with smaller laser energy. However, since the first cell layer is removed together, as a result, substantially the same processing conditions as in Example 1 were appropriate.

1, 21 Substrate 2 Transparent electrode layer 3 Photoelectric conversion layer 4 Back electrode layer 5 Intermediate contact layer 6 Solar cell module 7 Power generation cell 12, 22 Separation groove 31 Amorphous silicon p layer 32 Amorphous silicon i layer 33 Amorphous Silicon n layer 41 Crystalline silicon p layer 42 Crystalline silicon i layer 43 Crystalline silicon n layer 80 Module connection portion 91 First cell layer 92 Second cell layer 100, 200 Photoelectric conversion device

Claims (4)

An integrated type in which a laminated body in which a transparent electrode layer, a photoelectric conversion layer, and a back electrode layer are stacked in order from the light incident side is supported by a substrate from either the transparent electrode layer or the back electrode layer. A method for manufacturing a photoelectric conversion device, comprising:
While intermittently irradiating a laser beam with a laser oscillator having a pulse width of 1 nanosecond or less on the surface opposite to the side supported by the substrate of the laminate, A separation groove forming step of forming a groove for electrically separating at least the layer including the surface by relatively moving the substrate and the laser oscillator;
In the separation groove forming step, the laser beam is irradiated under the condition that the cross-sectional shape of the laser beam is circular and the product of the laser energy density (J / cm ² ) and the number of times of irradiation (shot) is 3 or more and 12 or less. For manufacturing an integrated photoelectric conversion device. The photoelectric conversion layer includes a crystalline silicon p layer, a crystalline silicon i layer, and a silicon n layer,
2. The integrated photoelectric conversion according to claim 1, wherein in the separation groove forming step, a layer on the laser irradiated surface side of the crystalline silicon i layer is removed, and a groove is formed so that the crystalline silicon i layer is exposed. Device manufacturing method. The photoelectric conversion layer includes a compound semiconductor n layer and a compound semiconductor p layer,
2. The integrated photoelectric conversion device according to claim 1, wherein in the separation groove forming step, a layer on the laser irradiated surface side of the compound semiconductor p layer is removed, and a groove is formed so that the compound semiconductor p layer is exposed. Production method. On the condition that the product of the laser energy density (J / cm ² ) and the number of irradiation times (shot) is 3 or more and 12 or less, and the insulation resistance between the transparent electrode layer and the back electrode layer is 5 kΩ or more. The method for manufacturing an integrated photoelectric conversion device according to any one of claims 1 to 3, wherein the laser light is irradiated.

Images