Manufacturing method for dye-sensitized solar cell

Abstract

To provide a manufacturing method for a highly durable dye-sensitized solar cell.SOLUTION: A manufacturing method for a dye-sensitized solar cell includes forming an electrode and a light absorbing layer on a first substrate, dripping an electrolyte onto the first substrate on which the electrode and the light absorbing layer are formed, forming a counter electrode on a second substrate, applying a sealant containing a spacer to the first substrate or the second substrate, and bonding the first substrate and the second substrate together at a vacuum bonding pressure of 110 Pa-1000 Pa.SELECTED DRAWING: Figure 7E

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing a dye-sensitized solar cell. [Background technology]

[0002] Solar cells are expected to be used as power sources and energy harvesting elements for IoT (Internet of Things) devices. Solar cells are broadly classified into silicon-based solar cells, compound-based solar cells, and organic solar cells. Among organic solar cells, dye-sensitized solar cells (DSC) are known. Dye-sensitized solar cells generate electricity through an oxidation-reduction reaction using a dye for absorbing light and an electrolyte. The electrolyte used in dye-sensitized solar cells is classified into solid-type electrolyte and liquid-type electrolyte. The liquid-type electrolyte may be injected using, for example, the ODF (One Drop Filling) method. The dye-sensitized solar cell cell containing the injected electrolyte is sealed with an encapsulant. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7071767 Summary of the Invention [Problem to be solved by the invention]

[0004] The sealing material is formed on a glass substrate or a conductive film serving as an electrode. If the adhesion between the glass or conductive film and the sealing material is reduced due to aging or the like, the sealing material may peel off, causing the electrolyte in the cell to leak. There is a demand for a dye-sensitized solar cell with high durability and in which the sealing material is less likely to peel off.

[0005] An object of the present disclosure is to provide a method for producing a dye-sensitized solar cell having high durability. [Means for solving the problem]

[0006] One embodiment of a method for producing a dye-sensitized solar cell includes forming an electrode and a light absorbing layer on a first substrate, dripping an electrolyte onto the first substrate on which the electrode and the light absorbing layer have been formed, forming a counter electrode on a second substrate, applying a sealant containing a spacer to the first substrate or the second substrate, and bonding the first substrate and the second substrate together at a vacuum bonding pressure of 110 Pa to 1000 Pa. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide a method for producing a dye-sensitized solar cell having high durability. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view showing an example of the configuration of a dye-sensitized solar cell according to an embodiment. [Diagram 2] FIG. 2 is a diagram for explaining the power generation principle of a dye-sensitized solar cell. [Figure 3A] FIG. 3A is a graph showing comparative results of reliability tests at 85° C. and 85% RH for dye-sensitized solar cells fabricated with various vacuum lamination pressures and seal widths of 1.0-1.1 mm, 1.1-1.2 mm, 1.2-1.3 mm, and 1.3-1.4 mm. [Figure 3B] FIG. 3B is a graph showing an approximation curve showing the relationship between the lamination vacuum pressure and the time until liquid leakage, obtained from the results of a reliability test at 85° C. and 85% RH for dye-sensitized solar cells with a seal width of 1.0 to 1.1 mm. [Figure 4] FIG. 4 is a diagram showing a comparison of the remaining theoretical air bubbles at lamination vacuum pressures of 500 Pa, 1000 Pa, and 2000 Pa. [Diagram 5] FIG. 5 is a diagram showing the relationship between the lamination vacuum pressure and the seal gap in the manufactured dye-sensitized solar cell. [Figure 6] FIG. 6 is a graph showing a comparison of the IV characteristics of dye-sensitized solar cells manufactured at various vacuum pressures for lamination. [Figure 7A]FIG. 7A is a diagram showing a manufacturing process of a dye-sensitized solar cell. [Figure 7B] FIG. 7B is a diagram showing the manufacturing process of a dye-sensitized solar cell. [Figure 7C] FIG. 7C is a diagram showing a manufacturing process of a dye-sensitized solar cell. [Figure 7D] FIG. 7D is a diagram showing the manufacturing process of a dye-sensitized solar cell. [Figure 7E] FIG. 7E is a diagram showing a manufacturing process of a dye-sensitized solar cell. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment will be described with reference to the drawings. Fig. 1 is a cross-sectional view showing an example of the configuration of a dye-sensitized solar cell according to an embodiment.

[0010] The dye-sensitized solar cell 1 according to one embodiment may include a plurality of dye-sensitized solar cell units. In Fig. 1, two units are shown. The number of units is not limited to two.

[0011] As shown in FIG. 1, each unit is formed between a first substrate 11 and a second substrate 12. The first substrate 11 is a transparent substrate such as a glass substrate. The first substrate 11 is used as an anode substrate. The second substrate 12 is disposed so as to face the first substrate 11. The second substrate 12 is a transparent substrate such as a glass substrate like the first substrate 11. The second substrate 12 is used as a cathode substrate.

[0012] An electrode 13 is formed at the position of each unit on the first substrate 11. The electrodes 13 are spaced apart such that there is no influence of leakage current between adjacent electrodes. The electrodes 13 are formed of a transparent conductive oxide (TCO) film such as indium tin oxide (ITO) or fluorine doped tin oxide (FTO). The electrodes 13 are used as anode electrodes. Although not shown in FIG. 1, the electrodes 13 of each unit are led out to the outside of the dye-sensitized solar cell 1. Terminals are formed on the led out electrodes 13. Wiring is led out from the terminals. This wiring is connected to one end of a load not shown.

[0013] A counter electrode 14 is formed at the position of each unit on the second substrate 12. The counter electrodes 14 are spaced apart such that there is no influence of, for example, leakage current between adjacent electrodes. Like the electrode 13, the counter electrode 14 is formed of a transparent conductive oxide film (TCO) such as indium tin oxide (ITO) or fluorine-doped tin oxide (FTO). The counter electrode 14 is used as a cathode electrode. Although not shown in FIG. 1, the counter electrode 14 of each unit is led out to the outside of the dye-sensitized solar cell 1. A terminal is formed on the led out counter electrode 14. Wiring is led out from the terminal. This wiring is connected to the other end of a load not shown.

[0014] An electron transport layer 15 is formed on each electrode 13. The electron transport layer 15 is made of titanium oxide (TiO x The electron transport layer 15 is made of a metal oxide film such as TCO, which has a higher resistance than metal. The electron transport layer 15 can be provided to suppress loss due to the electrode 13 made of TCO, which has a higher resistance than metal. In addition, the formation of the electron transport layer 15 improves the adhesion of the light absorbing layer 16, which is further formed on the electron transport layer 15.

[0015] A light absorbing layer 16 is formed on each of the electron transport layers 15. The light absorbing layer 16 is a layer formed by adsorbing a dye to an electron collector. The electron collector is, for example, an aggregate of a porous oxide semiconductor, for example, titanium oxide (TiO2). The dye is, for example, a ruthenium (Ru) dye (RU) (N719 dye, etc.). The electron collector is not limited to titanium oxide, but may be, for example, zinc oxide, tin oxide, tungsten oxide, niobium oxide, indium oxide, and a complex thereof. In addition, the dye is not limited to N719 dye. For example, N3 dye and BlackDye may be used as ruthenium-based dyes, and D149, xanthene, PVK, merocyanine, oxazine, etc. may be used as pure organic dyes.

[0016] A catalyst layer 17 is formed on each of the counter electrodes 14. The catalyst layer 17 is, for example, a platinum layer, a carbon layer, or the like.

[0017] An electrolyte solution 18 is filled between the light absorbing layer 16 and the catalyst layer 17. As a solvent for the electrolyte solution 18, for example, acetonitrile, methoxyacetonitrile, ethylene carbonate, or the like can be used. As a solute for the electrolyte solution 18, for example, iodine (I2), 1,2-dimethyl-3-n-propylimidazolium iodide (DMPImI), lithium iodide (LiI), 4-tert-butylpyridine (TBP), or the like can be used. As shown in FIG. 1, the electrolyte solution 18 is partitioned by a sealant 19. The sealant 19 bonds the first substrate 11 and the second substrate 12 together, and prevents the electrolyte solution 18 from leaking out to the outside. The sealant 19 can be a resin with excellent solvent resistance, such as an acrylic resin or an olefin resin. In addition, a spacer 19a is mixed into the sealant 19. The spacers 19a are mixed in to set the seal gap of the dye-sensitized solar cell 1, which in the example of FIG. 1 is the gap SG between the first substrate 11 and the second substrate 12, to a desired value. The spacers 19a may be granular spacers such as resin beads. The spacers 19a may be, for example, silica particles. The spacers 19a may also be conductive particles. When the spacers 19a are conductive particles, it is also possible to connect multiple dye-sensitized solar cell units 1 in series or in parallel via the sealing material 19.

[0018] 2 is a diagram for explaining the power generation principle of the dye-sensitized solar cell 1. In the following example, the electron collector is titanium oxide (TiO2), the dye is a ruthenium (Ru) dye, and the electrolyte 18 is an iodine (I) electrolyte.

[0019] First, when light is incident on the dye-sensitized solar cell 1, the light is absorbed by the dye 16a formed on the substrate. The dye 16a is excited by absorbing the light. The reaction formula is, for example, shown in the following formula (1). Ru → Ru + +e - (1)

[0020] Electrons emitted from the excited dye 16a (e -The electrons injected into the electron collector 16b move to the electrode 13, which is an anode electrode.

[0021] On the other hand, electrons (e - The dye 16a that has lost the ion exchange function reacts with, for example, iodide ions (I - ) in electrolyte 18. - ) is an electron (e - ) to dye 16a, triiodide ion (I3 - The reaction formula is shown in the following formulas (2) and (3). Ru+e - →Ru (2) 3I - →I3 - +2e - (3)

[0022] The triiodide ion (I3 - ) is transferred from the counter electrode 14, which is the cathode, to the electrons (e - ) is received by the counter electrode 14. At this time, a potential difference is generated between the counter electrode 14 and the electrode 13. If a load is connected between the counter electrode 14 and the electrode 13, the electrons that have moved to the electrode 13 will move through the load to the counter electrode 14. Then, the electrons that have reached the counter electrode 14 will be converted into triiodide ions (I3 - ) is absorbed by the iodide ion (I3 - ) is the iodide ion (I - ) The reaction formula is shown, for example, in the following formula (4). I3 - +2e - →3I - (4)

[0023] The above-mentioned redox reaction is repeated to generate electricity in the dye-sensitized solar cell 1. For such a redox reaction to occur, the energy level of the dye 16a in the excited state must be higher than the energy level of the electron collector 16b, and the energy level of the dye 16a in the ground state must be lower than the energy level of the electrolyte 18.

[0024] Here, depending on the usage environment of the dye-sensitized solar cell 1 or over a long period of use, leakage of the electrolyte solution 18 from the sealing material 19 of the dye-sensitized solar cell 1 may occur. The leakage occurs, for example, when the adhesion between the first substrate 11 or the second substrate 12 and the sealing material 19 decreases, causing a part of the sealing material 19 to peel off. One of the causes of the decrease in adhesion of the sealing material 19 is the vacuum pressure applied when the first substrate 11 and the second substrate 12 are bonded together by the sealing material 19. Specifically, in bonding in a medium vacuum range (up to about 100 Pa), residual stress in the sealing material 19 makes the sealing material 19 more likely to peel off.

[0025] To prevent leakage, the seal width of the sealant 19 (the width in the direction perpendicular to the gap direction of the sealant 19, w in FIG. 1) s ) is effective. On the other hand, when considering reducing the cell size of the dye-sensitized solar cell 1, increasing the seal width of the sealant 19 leads to a decrease in the effective area effective for power generation of the dye-sensitized solar cell 1. Therefore, it is required to prevent liquid leakage while shortening the seal width of the sealant 19 as much as possible. In the embodiment, liquid leakage from the sealant 19 is prevented by controlling the lamination vacuum pressure of the sealant 19 to an appropriate value.

[0026] FIG. 3A shows the results of a 85°C 85% RH reliability test of dye-sensitized solar cells produced with various lamination vacuum pressures at seal widths of 1.0-1.1 mm, 1.1-1.2 mm, 1.2-1.3 mm, and 1.3-1.4 mm. In the test, dye-sensitized solar cells were produced with various seal widths and different lamination vacuum pressures, and the time until leakage occurred was measured when each dye-sensitized solar cell was exposed to a temperature of 85°C and a relative humidity of 85%. The vertical axis of FIG. 3A shows the ratio of the time until leakage to the time until leakage of a dye-sensitized solar cell with a seal width of 1.0-1.1 mm and a lamination vacuum pressure of 13 Pa, which is set to 1. As shown in FIG. 3A, the time until leakage becomes longer as the lamination vacuum pressure increases, i.e., the vacuum becomes lower. For example, the time until liquid leakage from the dye-sensitized solar cell 1 produced at a lamination vacuum pressure of 1000 Pa is improved to 5.5 times the time until liquid leakage from the dye-sensitized solar cell 1 produced at a lamination vacuum pressure of 13 Pa.

[0027] Figure 3B shows an approximation curve representing the relationship between lamination vacuum pressure and time to leakage obtained from the 85℃ 85% RH reliability test results of dye-sensitized solar cells with a seal width of 1.0-1.1 mm. As shown in Figure 3B, when the seal width is 1.0-1.1 mm, the time to leakage increases significantly when the lamination vacuum pressure is increased from 13 Pa to 500 Pa, but does not change significantly when the lamination vacuum pressure is increased from 1000 Pa to 2000 Pa.

[0028] The reason why the time until leakage is extended by increasing the lamination vacuum pressure is because theoretical bubbles remain in the electrolyte 18 due to the increase in the lamination vacuum pressure. FIG. 4 is a diagram showing a comparison of the state of the remaining theoretical bubbles at lamination vacuum pressures of 500 Pa, 1000 Pa, and 2000 Pa. As shown in FIG. 4, when the lamination vacuum pressure is 500 Pa, almost no theoretical bubbles are observed. On the other hand, when the lamination vacuum pressure increases to 1000 Pa, theoretical bubbles B begin to remain. Furthermore, when the lamination vacuum pressure increases to 2000 Pa, large theoretical bubbles B remain. The theoretical bubbles B act as a cushion that suppresses the pulling of the sealing material 19 caused by the expansion of the sealing material 19 due to an increase in temperature, etc. The durability of the dye-sensitized solar cell 1 can be improved by the action of the theoretical bubbles B.

[0029] FIG. 5 is a diagram showing the relationship between the lamination vacuum pressure and the seal gap in the dye-sensitized solar cell to be manufactured. Here, in FIG. 5, the particle size of the spacer 19a is 15 μm, and the seal gap of 15 μm is the target seal gap. As shown in FIG. 5, the seal gap of the dye-sensitized solar cell to be manufactured is more likely to be 15 μm as the lamination vacuum pressure is lower. This is because the low lamination vacuum pressure applies an appropriate pressure to the spacer 19a mixed in the sealing material 19. On the other hand, as the lamination vacuum pressure is higher, the pressure applied to the spacer 19a is lower, and the amount of crushing of the spacer 19a is reduced. As a result, the seal gap of the dye-sensitized solar cell to be manufactured is more likely to be larger than the target seal gap.

[0030] Based on the above results, from the viewpoint of leaving theoretical bubbles to ensure the durability of the sealing material 19, the higher the lamination vacuum pressure, the better, and from the viewpoint of making it easier to obtain the target seal gap, the lower the lamination vacuum pressure, the better. The lamination vacuum pressure that achieves both of these is, for example, 1000 Pa. On the other hand, even if theoretical bubbles are hardly confirmed, if there is a certain degree of lamination vacuum pressure, the remaining stress in the sealing material 19 is reduced and the time until liquid leakage is extended. In addition, the seal gap does not necessarily need to be 15 μm, and some error is acceptable. Therefore, in the embodiment, for example, 110 Pa-1000 Pa is adopted as the range of the lamination vacuum pressure. In this case, the seal gap is within 15 μm±0.1 μm.

[0031] FIG. 6 is a diagram showing a comparison of IV characteristics of dye-sensitized solar cells manufactured at various lamination vacuum pressures. In FIG. 6, IV characteristics at lamination vacuum pressures of 13 Pa, 220 Pa, 1000 Pa, and 2000 Pa are shown. The IV characteristics of a dye-sensitized solar cell is one of the indicators of the performance of the dye-sensitized solar cell. As shown in FIG. 6, there is almost no difference in IV characteristics at any lamination vacuum pressure of 13 Pa, 220 Pa, 1000 Pa, and 2000 Pa. In other words, there is almost no difference in performance within the lamination vacuum pressure range of 110 Pa to 1000 Pa. Therefore, at a lamination vacuum pressure of 110 Pa to 1000 Pa, the durability can be improved while the target seal gap is achieved.

[0032] Next, a method for manufacturing the dye-sensitized solar cell 1 will be described. Figures 7A to 7E are diagrams showing the manufacturing process of the dye-sensitized solar cell 1. In this embodiment, an anode substrate on which an anode electrode is formed and a cathode substrate on which a cathode electrode is formed are separately formed, and then the two are bonded together to manufacture the dye-sensitized solar cell 1.

[0033] First, a method for manufacturing an anode substrate will be described with reference to Figs. 7A to 7C. As shown in Fig. 7A, an electrode 13, an electron transport layer 15, and a light absorbing layer 16 are formed in sequence on a first substrate 11 such as a glass substrate. For example, a transparent conductive oxide film such as an ITO film and a titanium oxide (TiO xAfter the SiO2 film is formed in sequence, the transparent conductive oxide film and the titanium oxide film are etched to match the shapes of the electrode 13 and the electron transport layer 15. Then, the light absorbing layer 16 is formed on the electron transport layer 15 of each unit. For this purpose, a paste of, for example, TiO2 as an electron collector is first formed on the electron transport layer 15 of each unit by a method such as screen printing. Then, the TiO2 paste formed on the electron transport layer 15 of each unit is baked at a high temperature such as 300°C to 550°C for about 60 minutes to 240 minutes. Furthermore, a dye is deposited on the baked TiO2 film. For example, the TiO2 film is immersed in a dye solution at room temperature for about 16 to 48 hours to deposit the dye. The film thickness of the anode electrode is the sum of the film thicknesses of the electrode 13, the electron transport layer 15, and the light absorbing layer 16. In reality, the film thickness of the anode electrode is almost equal to the film thickness of the light absorbing layer 16.

[0034] Next, as shown in Fig. 7B, a sealant 19 is applied by a method such as dispensing. Although not shown in Fig. 7B, when a plurality of dye-sensitized solar cells 1 are formed on the first substrate 11, a peripheral seal may be formed to surround the outermost dye-sensitized solar cell 1. Granular spacers with a particle size of about 15 µm, for example, resin beads, are mixed into the sealant 19. The amount of the resin beads mixed in is, for example, about 1.25% by weight of the sealant 19, but is not limited thereto. The sealant 19 may be applied to the cathode substrate instead of the anode substrate.

[0035] 7C, the electrolyte solution 18 is applied onto the light absorbing layer 16. In the embodiment, the electrolyte solution 18 is applied onto the first substrate 11 by a dripping method.

[0036] Next, a method for manufacturing a cathode substrate will be described with reference to Fig. 7D. As shown in Fig. 7D, a counter electrode 14 and a catalyst layer 17 are formed in sequence on a second substrate 12 such as a glass substrate. For example, a transparent conductive oxide film such as an ITO film and a platinum film are formed in sequence on the second substrate 12, and then the transparent conductive oxide film and the platinum film are etched to match the shapes of the counter electrode 14 and the catalyst layer 17. In this manner, a cathode substrate is manufactured.

[0037] After the anode substrate and the cathode substrate are manufactured, the anode substrate and the cathode substrate are bonded together via a sealant 19, as shown in Fig. 7E. By performing the bonding at a vacuum pressure in the range of 110 Pa to 1000 Pa, a desired seal gap can be obtained, and improved durability is also expected.

[0038] Here, in the embodiment, the electrolyte solution 18 is sealed inside the dye-sensitized solar cell 1 by the ODF method. Alternatively, the electrolyte solution 18 may be sealed inside the dye-sensitized solar cell 1 by the injection method. In this case, the electrolyte solution 18 is not dropped, and the anode substrate and the cathode substrate are bonded together first. The bonding of the anode substrate and the cathode substrate does not necessarily need to be performed under a bonding vacuum pressure of 110 Pa to 1000 Pa. After the anode substrate and the cathode substrate are bonded together, the electrolyte solution 18 is injected through an injection port previously formed in the sealing material 19, and the injection port is then sealed. This injection is performed under a vacuum pressure of 110 Pa to 1000 Pa, which can improve the durability of the dye-sensitized solar cell.

[0039] As described above, in the embodiment, the substrates are bonded at a vacuum pressure determined based on durability. The dye-sensitized solar cell manufactured by this manufacturing method has high resistance to leakage and the like. In addition, since the vacuum pressure is changed without changing the seal width, high durability can be obtained while preventing the seal width of the sealant 19 from becoming unnecessarily large, and therefore the effective area can be increased.

[0040] The present invention is not limited to the above-mentioned embodiment, and various modifications can be made in the implementation stage without departing from the gist of the invention. In addition, the embodiments may be implemented in appropriate combination, and in that case, the combined effect can be obtained. Furthermore, the above-mentioned embodiment includes various inventions, and various inventions can be extracted by combinations selected from the multiple components disclosed. For example, if the problem can be solved and the effect can be obtained even if some components are deleted from all the components shown in the embodiment, the configuration from which the components are deleted can be extracted as an invention. [Explanation of symbols]

[0041] 1 dye-sensitized solar cell, 11 first substrate, 12 second substrate, 13 electrode, 14 counter electrode, 15 electron transport layer, 16 light absorption layer, 16a dye, 16b electron collector, 17 catalyst layer, 18 electrolyte, 19 sealing material, 19a spacer.

Claims

1. forming an electrode and a light absorbing layer on a first substrate; Dropping an electrolyte onto the first substrate on which the electrodes and the light absorbing layer are formed; forming a counter electrode on a second substrate; Applying a sealing material including a spacer to the first substrate or the second substrate; bonding the first substrate and the second substrate together at a bonding vacuum pressure of 110 Pa to 1000 Pa; A method for manufacturing a dye-sensitized solar cell comprising the steps of:

2. The particle size of the spacer is 15 μm; The lamination vacuum pressure is 1000 Pa. A method for producing the dye-sensitized solar cell according to claim 1 .

3. forming an electrode and a light absorbing layer on a first substrate; forming a counter electrode on a second substrate; Applying a sealing material including a spacer and having an injection port formed therein to the first substrate or the second substrate; bonding the first substrate and the second substrate together; Injecting an electrolyte solution from the injection port at a vacuum pressure of 10 Pa to 1000 Pa; sealing the inlet; A method for manufacturing a dye-sensitized solar cell comprising the steps of:

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