JP2009059772A - Method of manufacturing solar battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a position shift during film formation of a flexible substrate without deteriorating the film quality of a solar battery. <P>SOLUTION: When the solar battery is manufactured, the film substrate 11 is heat-treated at a temperature higher than the glass transition point of the film substrate 11 while applying constant tension to the film substrate 11, and then subjected to a filming treatment while applying the same tension as the tension applied to the film substrate 11 during the heat treatment. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a solar cell, and is particularly suitable for application to a method for forming a solar cell on a film substrate.

  As a method for producing a thin film photoelectric conversion element with high productivity, each layer including a photoelectric conversion layer mainly composed of a-Si is formed on a flexible substrate made of a long polymer material or a metal such as stainless steel. There is a way to do it. Here, as a method of forming a plurality of layers on a long flexible substrate, a roll-to-roll method of forming a film on a flexible substrate moving in each film formation chamber, and a stop in the film formation chamber are used. There is a stepping roll method in which after forming a film on a flexible substrate, the flexible substrate portion after film formation is sent out of the film formation chamber. And, in order to prevent the downward deflection and displacement due to the weight of the flexible substrate, in order to convey the flexible substrate while applying tension to the flexible substrate, and to improve the film quality, A film forming process such as CVD or sputtering is performed while heating the flexible substrate (Patent Document 1). Here, the heat resistance of a film substrate made of a polymer material such as polyimide is low, and it is known that plastic deformation occurs depending on the temperature required for the film forming process.

FIG. 4 is a diagram showing the amount of plastic deformation of the film substrate when it is heat-treated while applying tension.
In FIG. 4, for example, when polyimide (Toray DuPont Kapton 200EN) is used as a film substrate, if the temperature of the film substrate is raised from room temperature while applying 80 g of tension to the film substrate, the elongation of the film substrate at the glass transition point. Even if the amount is rapidly increased and the temperature of the film substrate is lowered to room temperature, the elongation of the film substrate does not return to the original state, and plastic deformation occurs in the film substrate.

In addition, as shown in FIG. 5, when the film substrate once plastically deformed ((11) → (12)) is subjected to a heat treatment again with a reduced tension, the film substrate shrinks, The amount of plastic deformation of the film substrate is reduced ((13) → (14)).
JP-A-8-283491

However, as shown in FIG. 6, the plastic deformation amount of the film substrate does not become constant for each lot, and the deformation amount varies for each lot. For this reason, even if alignment is performed in advance with the amount of plastic deformation of the film substrate taken into account, there is a problem in that the positional deviation during film formation cannot be completely eliminated and the characteristics of the solar cell are deteriorated. It was.
In addition, in the conventional solar cell manufacturing process, the tension applied to the film substrate is individually set for each process, and the amount of plastic deformation changes for each process. There was a problem.
Therefore, an object of the present invention is to provide a method for manufacturing a solar cell that can suppress a positional shift during film formation of a flexible substrate without deteriorating the film quality.

  In order to solve the above-described problem, according to the method for manufacturing a solar cell according to claim 1, the flexible substrate is heated at a temperature equal to or higher than a glass transition point of the flexible substrate while applying a constant tension to the flexible substrate. Performing a first heat treatment of the flexible substrate, and performing a second heat treatment of the flexible substrate while applying the same tension as that applied to the flexible substrate in the first heat treatment. It is characterized by providing.

  This makes it possible to perform a second heat treatment such as a degassing process in a state in which the flexible substrate has undergone plastic deformation, and variations in the amount of plastic deformation of the flexible substrate for each lot in the second heat treatment. In addition to being able to absorb, it is possible to prevent the amount of plastic deformation of the flexible substrate that has once undergone plastic deformation during the first heat treatment from changing during the second heat treatment. For this reason, even when the flexible substrate undergoes plastic deformation depending on the temperature required for the second heat treatment, the positional deviation during the heat treatment of the flexible substrate is ensured while ensuring the temperature necessary for the second heat treatment. It becomes possible to suppress, and the characteristic of a solar cell can be improved.

According to the method for manufacturing a solar cell according to claim 2, the step of heat-treating the flexible substrate at a temperature equal to or higher than the glass transition point of the flexible substrate while applying a constant tension to the flexible substrate. When,
And performing a film forming process on the flexible substrate while applying the same tension as that applied to the flexible substrate in the heat treatment.
This makes it possible to perform the film forming process in a state where the flexible substrate is plastically deformed, and to absorb the variation in the amount of plastic deformation of the flexible substrate for each lot in the film forming process. In addition, the amount of plastic deformation of the flexible substrate that has once undergone plastic deformation during heat treatment can be prevented from changing during film formation. For this reason, even when the flexible substrate undergoes plastic deformation depending on the temperature required for the film forming process, the positional deviation during the film forming process of the flexible substrate is ensured while ensuring the temperature necessary for the film forming process. It becomes possible to suppress, and the characteristic of a solar cell can be improved.

  According to the method for manufacturing a solar cell according to claim 3, the step of heat-treating the flexible substrate at a temperature equal to or higher than the glass transition point of the flexible substrate while applying a constant tension to the flexible substrate. A step of forming a series hole in the heat-treated flexible substrate, and a step of forming the series hole while applying the same tension as that applied to the flexible substrate in the heat treatment. A back-side electrode and a back-side electrode are formed on the degassed flexible substrate while applying the same tension as that applied to the flexible substrate in the heat treatment and a step of degassing the substrate. A step of forming current collecting holes in the flexible substrate on which the back electrode and the back electrode are formed, a step of forming a first groove for dividing the back electrode, and the heat treatment to form the flexible substrate. Give the same tension as given to , Sequentially forming a photoelectric conversion layer and a transparent electrode layer on the back electrode, and forming a second groove for dividing the back electrode so as to be alternately arranged with the first groove. It is characterized by.

  As a result, it is possible to suppress the positional shift during the degassing process or the film forming process of the flexible substrate while securing the temperature necessary for the degassing process or the film forming process, and a complicated wiring process. Without being used, the photoelectric conversion layers formed on the flexible substrate can be connected in series. For this reason, while suppressing complication of the manufacturing process, it is possible to increase the voltage output from the solar cell, improve the characteristics of the solar cell, and provide a high-quality solar cell at low cost. be able to.

  As described above, according to the present invention, it is possible to suppress misalignment during the heat treatment of the flexible substrate while ensuring the temperature necessary for the heat treatment, and to improve the characteristics of the solar cell. .

Hereinafter, a method for manufacturing a solar cell according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a method for manufacturing a solar cell according to an embodiment of the present invention.
In FIG. 1, a photoelectric conversion layer 13 is laminated on a film substrate 11 via a back electrode layer 12, and a transparent electrode layer 14 is laminated on the photoelectric conversion layer 13. A back electrode layer 15 is formed on the back surface of the film substrate 11. The back electrode layer 15 is, for example, an Ag / ZnO laminated structure and a Ni layer, the back electrode layer 12 is, for example, an Ag / ZnO laminated structure, and the film substrate 11 is, for example, a resin film such as polyimide or polyethylene. As the photoelectric conversion layer 13, for example, a pin structure made of amorphous silicon, and as the transparent electrode layer 14, for example, ITO can be used. Moreover, the thickness of the photoelectric converting layer 13 can be about 1 micrometer, for example, and the thickness of the film substrate 11 can be about 50 micrometers, for example.

  The back electrode layer 15 has a groove 19 that divides the back electrode layer 15, and the back electrode layer 12, the photoelectric conversion layer 13, and the transparent electrode layer 14 have a back electrode layer 12 and a photoelectric conversion layer 13. And the groove | channel 18 which divides | segments the transparent electrode layer 14 is alternately formed in parallel with the groove | channel 19, and unit cell U1-U4 is comprised. In the film substrate 11, a series hole 16 for connecting the divided photoelectric conversion layers 13 in series is formed for each unit cell U <b> 1 to U <b> 4, and the back electrode layer 15 and the back electrode layer 12 separated by the film substrate 11. Are connected to each other via a series hole 16.

The film substrate 11, the back electrode layer 12, and the back electrode layer 15 are formed with current collecting holes 17 for collecting charges generated in the photoelectric conversion layer 13 on the back electrode layer 15 side for each of the unit cells U1 to U4. The photoelectric conversion layer 13 and the transparent electrode layer 14 are connected to the back electrode layer 15 through a current collecting hole 17.
Here, the series holes 16 of the unit cells U1 to U4 are respectively connected to the back electrode layer 15 immediately below the unit cells U1 to U4, and each unit is connected to the back electrode layer 15 adjacent to the back electrode layer 15 to which the series holes 16 are connected. The arrangement positions of the series holes 16 and the current collecting holes 17 can be determined so that the current collecting holes 17 of the cells U1 to U4 are connected.

As a result, the photoelectric conversion layers 13 divided on the film substrate 11 can be connected in series only with a thin film, and a voltage suitable for an inverter can be obtained without external wiring. Can be configured.
When the solar cell of FIG. 1 is manufactured, the film substrate 11 is heat-treated at a temperature equal to or higher than the glass transition point of the film substrate 11 while applying a certain tension to the film substrate 11, and is given to the film substrate 11 by the heat treatment. The film forming process of the film substrate 11 can be performed while applying the same tension as that described above.

  Thereby, it becomes possible to perform the film forming process in a state where the film substrate 11 has undergone plastic deformation, and it becomes possible to absorb the variation in the amount of plastic deformation of the film substrate 11 for each lot in the film forming process, It is possible to prevent the amount of plastic deformation of the film substrate 11 that has undergone plastic deformation during the heat treatment from changing during the film formation process. For this reason, even when the film substrate 11 undergoes plastic deformation depending on the temperature required for the film forming process, the positional deviation during the film forming process of the film substrate 11 is suppressed while ensuring the temperature necessary for the film forming process. And the characteristics of the solar cell can be improved.

FIG. 2 is a block diagram showing a manufacturing process of the solar cell according to one embodiment of the present invention.
In FIG. 2, the film substrate 1 is annealed at a temperature equal to or higher than the glass transition point of the film substrate 11 while applying a constant tension to the film substrate 11 (K11). Note that the tension applied in this annealing process can be set to the strongest tension applied to the film substrate 1 in the subsequent processes. For example, when polyimide (Toray DuPont Kapton 200EN) is used as the film substrate 11, the temperature of the film substrate 11 is 20 ° C. → 350 ° C. (2 to 3 minutes) → 20 ° C., and the tension is 16 kg / It can be set to be 1000 mm.

Next, a series hole 16 is formed in the film substrate 11 by a method such as a die press (K12). A mark hole for identifying the position of the film substrate 11 can be formed simultaneously with the formation of the series hole 16.
Next, the film substrate 11 is degassed by performing vacuum heating of the film substrate 11 while applying the same tension as that applied to the film substrate 11 in the annealing process (K13). For example, the conditions for degassing the film substrate 11 can be set such that the temperature is 20 ° C. → 350 ° C. → 20 ° C. and the tension is 16 kg / 1000 mm.

Next, the back electrode 12 and the back electrode 15 having an Ag / ZnO laminated structure are made to be the film substrate 11 by performing a sputtering process while applying the same tension to the film substrate 11 as that applied to the film substrate 11 by the annealing process. (K14). In addition, as conditions for the sputtering process at this time, for example, the temperature can be set to 20 ° C. → 300 ° C. → 20 ° C., and the tension can be set to 16 kg / 1000 mm.
Next, current collecting holes 17 are formed in the film substrate 11 by a method such as a die press (K15).
Next, a groove 18 for dividing the back electrode 12 is formed by a method such as laser scribing (K16).

  Next, by performing the CVD or sputtering process while applying the same tension as that applied to the film substrate 11 by the annealing process, the photoelectric conversion layer 13 made of a-Si and the transparent electrode layer 14 made of ITO are changed to the film substrate. 11 are sequentially formed on the front surface side of the film 11, and a Ni electrode is formed on the back surface side of the film substrate 11 (K17). The conditions for CVD or sputtering treatment at this time can be set so that, for example, the temperature is 20 ° C. → 320 ° C. → 20 ° C. and the tension is 16 kg / 1000 mm.

Next, the transparent electrode layer 14 is patterned by a method such as photoetching so that the transparent electrode layer 14 on the series hole 16 is removed (K17).
Next, grooves 19 for dividing the back electrode 15 are formed so as to be alternately arranged in parallel with the grooves 18 (K19).
As a result, it is possible to suppress a positional shift during the degassing process or the film forming process of the film substrate 11 while securing a temperature necessary for the degassing process or the film forming process, and a complicated wiring process is used. The photoelectric conversion layer 13 formed on the film substrate 11 can be connected in series without any problem. For this reason, while suppressing complication of the manufacturing process, it is possible to increase the voltage output from the solar cell, improve the characteristics of the solar cell, and provide a high-quality solar cell at low cost. be able to.

FIG. 3 is a diagram showing the amount of plastic deformation of the film substrate when heat treatment is performed while applying tension in the manufacturing process of the solar cell according to one embodiment of the present invention.
In FIG. 3, for example, when polyimide (Toray DuPont Kapton 200EN) is used as the film substrate 11, the temperature of the film substrate is increased from 20 ° C. to 350 ° C. while applying a tension of 16 g to the film substrate 11 (1), Thereafter, when the temperature of the film substrate 11 is lowered to 20 ° C. (2), plastic deformation occurs in the film substrate 11. And even if the temperature of the film substrate 11 is raised or lowered within a temperature range below the glass transition point while applying a tension of 16 g to the film substrate 11 (3), the plastic deformation amount R of the film substrate 11 thereafter is an error. In this range, it is possible to reduce the positional deviation during the film forming process of the film substrate 11 in the subsequent processes.

It is a perspective view which shows schematic structure of the solar cell which concerns on one Embodiment of this invention. It is a block diagram which shows the manufacturing process of the solar cell which concerns on one Embodiment of this invention. It is a figure which shows the plastic deformation amount of a film substrate when heat-processing, applying the tension | tensile_strength in the manufacturing process of the solar cell which concerns on one Embodiment of this invention. It is a figure which shows the amount of plastic deformation of a film substrate when heat-processing, applying a tension | tensile_strength. It is a figure which shows the amount of plastic deformation of a film substrate when heat-processing, changing tension | tensile_strength. It is a figure which shows the dispersion | variation for every lot of the plastic deformation amount of a film substrate when heat-processing, applying a tension | tensile_strength.

Explanation of symbols

U1-U4 unit cell 11 film substrate 12 back electrode layer 13 photoelectric conversion layer 14 transparent electrode layer 15 back electrode layer 16 series hole 17 current collecting hole 18, 19 groove

Claims (3)

Performing a first heat treatment of the flexible substrate at a temperature equal to or higher than a glass transition point of the flexible substrate while applying a constant tension to the flexible substrate;
And a second heat treatment of the flexible substrate while applying the same tension as that applied to the flexible substrate in the first heat treatment. Performing a heat treatment of the flexible substrate at a temperature equal to or higher than a glass transition point of the flexible substrate while applying a certain tension to the flexible substrate;
And a film forming process for the flexible substrate while applying the same tension as that applied to the flexible substrate by the heat treatment. Performing a heat treatment of the flexible substrate at a temperature equal to or higher than a glass transition point of the flexible substrate while applying a certain tension to the flexible substrate;
Forming serial holes in the heat treated flexible substrate;
Degassing the flexible substrate in which the series holes are formed while applying the same tension as that applied to the flexible substrate in the heat treatment;
Forming a back electrode and a back electrode on the degassed flexible substrate while applying the same tension as that applied to the flexible substrate in the heat treatment;
Forming a current collecting hole in the flexible substrate on which the back electrode and the back electrode are formed;
Forming a first groove for dividing the back electrode;
A step of sequentially forming a photoelectric conversion layer and a transparent electrode layer on the back electrode while applying the same tension as that applied to the flexible substrate in the heat treatment;
Forming a second groove that divides the back electrode so as to be alternately arranged with the first groove.

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