METHOD FOR MANUFACTURING SOLAR CELL, AND SOLAR CELL

Abstract

The present invention aims to provide a method for producing a solar cell in which a continuous long scribed line is provided along the machine direction of a substrate so that failures due to breakage of the scribed line are reduced. Provided is a method for producing a solar cell, the method being for producing plural monolithic solar cells in batches by a roll-to-roll method, the method including: step (1) of forming a lower electrode on a long substrate and scribing the lower electrode to provide a scribed line along the machine direction of the substrate; step (2) of forming a photoelectric conversion layer on the lower electrode provided with the scribed line and scribing the photoelectric conversion layer to provide a scribed line along the machine direction of the substrate; step (3) of forming an upper electrode on the photoelectric conversion layer provided with the scribed line and scribing the upper electrode to provide a scribed line along the machine direction of the substrate, the scribing in at least one of the steps (1) to (3) including: step (a) of providing a first scribed line; step (b) of providing a second scribed line; and step (c) of providing a third scribed line.

Claims

1. A method for producing a solar cell, the method being for producing plural monolithic solar cells in batches by a roll-to-roll method, the method comprising: a step (1) of forming a lower electrode on a long substrate and scribing the lower electrode to provide a scribed line along the machine direction of the substrate; a step (2) of forming a photoelectric conversion layer on the lower electrode provided with the scribed line and scribing the photoelectric conversion layer to provide a scribed line along the machine direction of the substrate; and a step (3) of forming an upper electrode on the photoelectric conversion layer provided with the scribed line and scribing the upper electrode to provide a scribed line along the machine direction of the substrate, the scribing in at least one of the steps (1) to (3) including: a step (a) of placing a laminate including the lower electrode, the photoelectric conversion layer, or the upper electrode on a stage of a scribing device and scribing the lower electrode, the photoelectric conversion layer, or the upper electrode to provide a first scribed line; a step (b) of shifting the laminate by the length of the stage of the scribing device and scribing the lower electrode, the photoelectric conversion layer, or the upper electrode to provide a second scribed line; and a step (c) of scribing the lower electrode, the photoelectric conversion layer, or the upper electrode in such a manner that the end point of the first scribed line and the start point of the second scribed line are connected to each other to provide a third scribed line.

2. The method for producing a solar cell according to claim 1, wherein the scribing pressure for providing the third scribed line in the step (c) is set lower than the scribing pressure for providing the first scribed line and the second scribed line.

3. The method for producing a solar cell according to claim 1, wherein the step (c) is conducted after the step (a), and the step (a) and the step (c) are a continuous series of steps.

4. The method for producing a solar cell according to claim 1, wherein the photoelectric conversion layer contains an organic-inorganic perovskite compound represented by the formula R-M-X.sub.3, wherein R represents an organic molecule; M represents a metal atom; and X represents a halogen atom or a chalcogen atom.

5. A solar cell obtained by the method for producing a solar cell according to claim 1.

6. The method for producing a solar cell according to claim 2, wherein the step (c) is conducted after the step (a), and the step (a) and the step (c) are a continuous series of steps.

7. The method for producing a solar cell according to claim 2, wherein the photoelectric conversion layer contains an organic-inorganic perovskite compound represented by the formula R-M-X.sub.3, wherein R represents an organic molecule; M represents a metal atom; and X represents a halogen atom or a chalcogen atom.

8. The method for producing a solar cell according to claim 3, wherein the photoelectric conversion layer contains an organic-inorganic perovskite compound represented by the formula R-M-X.sub.3, wherein R represents an organic molecule; M represents a metal atom; and X represents a halogen atom or a chalcogen atom.

9. The method for producing a solar cell according to claim 6, wherein the photoelectric conversion layer contains an organic-inorganic perovskite compound represented by the formula R-M-X.sub.3, wherein R represents an organic molecule; M represents a metal atom; and X represents a halogen atom or a chalcogen atom.

10. A solar cell obtained by the method for producing a solar cell according to claim 2.

11. A solar cell obtained by the method for producing a solar cell according to claim 3.

12. A solar cell obtained by the method for producing a solar cell according to claim 6.

13. A solar cell obtained by the method for producing a solar cell according to claim 4.

14. A solar cell obtained by the method for producing a solar cell according to claim 7.

15. A solar cell obtained by the method for producing a solar cell according to claim 8.

16. A solar cell obtained by the method for producing a solar cell according to claim 9.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0101] FIG. 1 is a top view schematically illustrating an exemplary method for providing scribed lines along the machine direction of a substrate by a roll-to-roll method.

[0102] FIG. 2 shows top views schematically illustrating exemplary connecting portions of scribed lines when the scribed lines are provided along the machine direction of a substrate by a roll-to-roll method.

[0103] FIG. 3 shows top views schematically illustrating exemplary scribing in the method for producing a solar cell of the present invention.

[0104] FIG. 4 is a schematic view of an exemplary crystal structure of an organic-inorganic perovskite compound.

DESCRIPTION OF EMBODIMENTS

[0105] Embodiments of the present invention are more specifically described with reference to, but not limited to, the following examples.

Example 1

(1) Production of a Solar Cell

(Step 1)

[0106] An aluminum foil (available from UACJ Corp., multipurpose aluminum material A1N30 grade, thickness: 100 m) was subjected to sulfuric acid anodizing for a treatment duration of 30 minutes, so that an aluminum oxide film (thickness: 5 m, proportion of thickness: 5%) was formed on a surface of the aluminum foil. Thereby, a substrate was obtained.

[0107] An Al film having a thickness of 100 nm was formed on an aluminum oxide film using a vapor deposition device while the substrate was shifted using a R to R device (SUPLaDUO available from Chugai Ro Co., Ltd.), and then a Ti film having a thickness of 100 nm was formed on the Al film by a vapor deposition method. Further, a TiO.sub.2 film was formed on the Ti film by a sputtering method. Thereby, a cathode was prepared.

[0108] A sample on which the cathode had been formed was placed on a stage of a mechanical scribing device (KMPD100 available from Mitsuboshi Diamond Industrial Co., Ltd.), and the cathode was scribed by mechanical patterning at a scribing pressure of 100 kPa. Thereby, a first scribed line was provided. The sample on which the cathode had been formed was shifted by the length of the stage of the mechanical scribing device, and the cathode was scribed by mechanical patterning at a scribing pressure of 100 kPa. Thereby, a second scribed line was provided. Further, the cathode was scribed by mechanical patterning at a scribing pressure of 90 kPa in such a manner that the end point of the first scribed line and the start point of the second scribed line were connected to each other. Thereby, a third scribed line (length: 100 m, shape: straight line, angle: 90) was provided. By repeating the above process, a continuous long scribed line was provided along the machine direction of the substrate.

[0109] The length, shape, and angle of the third scribed line were obtained by three-dimensional image analysis using a microscope (VN-8010 available from Keyence Corporation).

(Step 2)

[0110] A titanium oxide paste containing polyisobutyl methacrylate as an organic binder and titanium oxide (mixture of those with an average particle size of 10 nm and those with an average particle size of 30 nm) was applied to the cathode by a spin coating method, while the sample on which the cathode had been formed was shifted using a R to R device (TM-MC available from Hirano Tecseed Co., Ltd.). Then, the sample was fired at 200 C. for 30 minutes. Thereby, a porous electron transport layer with a thickness of 500 nm was formed.

[0111] Subsequently, lead iodide as a metal halide compound was dissolved in N,N-dimethylformamide (DMF) to prepare a 1 M solution. The resulting solution was applied to the porous electron transport layer by a spin coating method to form a film, while the sample on which the porous electron transport layer had been formed was shifted using the R to R device (TM-MC available from Hirano Tecseed Co., Ltd.). Separately, methylammonium iodide as an amine compound was dissolved in 2-propanol to prepare a 1 M solution. The sample with the above lead iodide film was immersed into this solution to form a layer containing CH.sub.3NH.sub.3PbI.sub.3 which is an organic-inorganic perovskite compound. Thereafter, the obtained sample was subjected to annealing treatment at 120 C. for 30 minutes.

[0112] Next, 68 mM of Spiro-OMeTAD (having a spirobifluorene skeleton), 55 mM of t-butyl pyridine, and 9 mM of a bis(trifluoromethylsulfonyl)imide silver salt were dissolved in 25 L of chlorobenzene to prepare a solution. This solution was applied to the photoelectric conversion layer by a spin coating method, while the sample on which the photoelectric conversion layer had been formed was shifted using the R to R device (TM-MC available from Hirano Tecseed Co., Ltd.). Thereby, a hole transport layer having a thickness of 150 nm was formed.

[0113] Subsequently, the layer that is a combination of the electron transport layer, the photoelectric conversion layer, and the hole transport layer was patterned using a laser scribing device (MPV-LD available from Mitsuboshi Diamond Industrial Co., Ltd.).

(Step 3)

[0114] An ITO film having a thickness of 100 nm was formed as an anode (transparent electrode) on the hole transport layer by a vapor deposition method, while the sample on which the hole transport layer had been formed was shifted using the R to R device (SUPLaDUO available from Chugai Ro Co., Ltd.). The ITO film was patterned using a mechanical scribing device.

(Step 4)

[0115] A barrier layer formed from ZnSnO having a thickness of 100 nm was formed on the anode by a sputtering method, while the sample on which the anode had been formed was shifted using a R to R device (RTC-5400 available from Toray Engineering Co., Ltd.). Then, the sample on which the barrier layer had been formed was cut to be divided to individual solar cells.

(2) Observation of Scribed Lines

[0116] The scribed lines provided on the cathode were observed by three-dimensional image analysis using a microscope (VN-8010 available from Keyence Corporation). Specifically, the overlap length of the third scribed line with the first scribed line and the overlap length of the third scribed line with the second scribed line were observed.

[0117] The cases where the third scribed line completely overlapped the first and second scribed lines were evaluated as o (Good). The cases where the third scribed line partly overlapped the first and second scribed line were evaluated as (Acceptable). The cases where the third scribed line did not overlap the first and second scribed lines and the first scribed line was not connected to the second scribed line were evaluated as x (Poor).

Examples 2 to 11, Comparative Examples 1 to 3

[0118] Solar cells were obtained as in Example 1, except that the scribing pressure was changed as shown in Table 1, that the length, shape, angle, and like properties of the third scribed line were changed by controlling the scribing conditions, and the timing when the step (c) was conducted was changed as shown in Table 1.

<Evaluation>

[0119] The solar cells obtained in the examples and comparative examples were evaluated as follows. Table 1 shows the results.

(Measurement of Photoelectric Conversion Efficiency)

[0120] A power source (model 236, available from Keithley Instruments Inc.) was connected between the electrodes of the solar cell. The photoelectric conversion efficiency was measured in an exposure area of 1 cm.sup.2 using a solar simulator (available from Yamashita Denso Corp.) at an intensity of 100 mW/cm.sup.2.

[0121] The photoelectric conversion efficiency values of the solar cells obtained in the examples and comparative examples were standardized with the photoelectric conversion efficiency of the solar cell obtained in Example 1 taken as 1.0. The cases where the standardized value was not less than 0.9 were evaluated as 00 (Excellent). The cases where the standardized value was less than 0.9 but not less than 0.7 were evaluated as o (Good). The cases where the standardized value was less than 0.7 but not less than 0.6 were evaluated as A (Acceptable). The cases where the standardized value was less than 0.6 were evaluated as x (Poor).

TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 First Scribing 100 75 100 100 100 100 100 100 scribed line pressure (step (a)) (kPa) Second Scribing 100 75 100 100 100 100 100 100 scribed line pressure (step (b)) (kPa) Third Scribing 90 65 90 90 90 90 90 20 scribed line pressure (step (c)) (kPa) Length (m) 100 100 50 100 100 100 100 100 Shape Straight Straight Straight Oblique Straight Straight Straight Straight line line line line line line line line Angle () 90 90 90 85 90 50 60 90 Timing of After After After After After After After After step (c) step (b) step (b) step (b) step (b) step (a) step (b) step (b) step (b) Evaluation Observation of scribed line Photoelectric conversion efficiency Comparative Comparative Comparative Example 9 Example 10 Example 11 Example 1 Exampel 2 Example 3 First Scribing 100 100 100 100 100 100 scribed line pressure (step (a)) (kPa) Second Scribing 100 100 100 100 100 100 scribed line pressure (step (b)) (kPa) Third Scribing 40 160 190 None 90 90 scribed line pressure (step (c)) (kPa) Length (m) 100 100 100 10 100 Shape Straight Straight Straight Straight Oblique line line line line line Angle () 90 90 90 90 40 Timing of After After After After After step (c) step (b) step (b) step (b) step (b) step (b) Evaluation Observation of x x x scribed line Photoelectric x x x conversion efficiency

INDUSTRIAL APPLICABILITY

[0122] The present invention can provide a method for producing a solar cell, the method being for producing plural monolithic solar cells in batches by a roll-to-roll method, in which a continuous long scribed line is provided along the machine direction of a substrate so that failures due to breakage of the scribed line are reduced. The present invention can also provide a solar cell obtained by the method for producing a solar cell.

REFERENCE SIGNS LIST

[0123] 1 stage of scribing device [0124] 2 laminate [0125] 3 first scribed line [0126] 4 second scribed line [0127] 5 third scribed line [0128] A connecting portion between first scribed line and second scribed line