Dye-sensitized solar cell

Abstract

To provide a dye-sensitized solar cell whose power generation performance is further improved.SOLUTION: A dye-sensitized solar cell includes an electrode, an electron transport layer, a light absorption layer, a counter electrode, a catalyst layer, an electrolyte solution, and a sealing material. The electrode is formed on a first substrate. The electron transport layer is formed on the electrode. The light absorption layer is formed on the electron transport layer and includes an electron collecting agent and a dye. The counter electrode is formed on a second substrate disposed facing the first substrate. The catalyst layer is formed on the counter electrode. The electrolyte solution fills a space between the light absorption layer and the catalyst layer. The sealing material is held between the first substrate and the second substrate and seals the electrode, the electron transport layer, the light absorption layer, the counter electrode, the catalyst layer, and the electrolyte solution. The light absorption layer has a thickness of 10 μm or less and the electron collecting agent has an average particle diameter of 16 nm or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to dye-sensitized solar cells. [Background technology]

[0002] Solar cells are expected to be used as power sources for IoT (Internet of Things) devices and as energy harvesting elements. Solar cells are broadly divided into silicon-based solar cells, compound-based solar cells, and organic solar cells. Among the organic solar cells, dye-sensitized solar cells (DSC) are well known. Dye-sensitized solar cells generate electricity through an oxidation-reduction reaction using a dye for absorbing light and an electrolyte. In recent years, there are expectations for further improvements in the power generation performance of dye-sensitized solar cells. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-12012 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to provide a dye-sensitized solar cell with further improved power generation performance. [Means for solving the problem]

[0005] A dye-sensitized solar cell according to one embodiment includes an electrode, an electron transport layer, a light absorbing layer, a counter electrode, a catalyst layer, an electrolyte, and a sealant. The electrode is formed on a first substrate. The electron transport layer is formed on the electrode. The light absorbing layer is formed on the electron transport layer and includes an electron collector and a dye. The counter electrode is formed on a second substrate disposed opposite the first substrate. The catalyst layer is formed on the counter electrode. The electrolyte is filled between the light absorbing layer and the catalyst layer. The sealant is interposed between the first substrate and the second substrate, and seals the electrode, the electron transport layer, the light absorbing layer, the counter electrode, the catalyst layer, and the electrolyte. The light absorbing layer has a thickness of 10 μm or less, and the average particle size of the electron collector is 16 nm or less. Effect of the Invention

[0006] According to the present disclosure, it is possible to provide a dye-sensitized solar cell with further improved power generation performance. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram 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 principle of power generation in a dye-sensitized solar cell. [Diagram 3] FIG. 3 is a diagram showing the relationship between the thickness of the light absorbing layer and the maximum output of the dye-sensitized solar cell. [Figure 4] FIG. 4 is a diagram for explaining the roughness factor. [Diagram 5] FIG. 5 is a diagram showing an example of the relationship between the average particle size and the roughness factor when the TiO2 film thickness is set to 10 μm. [Figure 6] FIG. 6 is a graph showing the relationship between the average particle size and the maximum output. [Figure 7] FIG. 7 is a flowchart showing a method for manufacturing a dye-sensitized solar cell in an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment will be described with reference to the drawings. FIG. 1 is a diagram showing an example of the configuration of a dye-sensitized solar cell according to an embodiment. As shown in FIG. 1, the dye-sensitized solar cell 1 has a first substrate 11 and a second substrate 12. The first substrate 11 is a transparent substrate such as a glass substrate. The second substrate 12 is disposed so as to face the first substrate 11. Like the first substrate 11, the second substrate 12 is a transparent substrate such as a glass substrate.

[0009] An electrode 13 is formed on the first substrate 11. The electrode 13 is formed of a transparent conductive oxide film (TCO) such as indium tin oxide (ITO) or fluorine-doped tin oxide (FTO). The electrode 13 is used as an anode electrode.

[0010] A counter electrode 14 is formed at a position facing the electrode 13 on the second substrate 12. 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) like the electrode 13. The counter electrode 14 is used as a cathode electrode.

[0011] An electron transport layer 15 is formed on the electrode 13. The electron transport layer 15 is made of titanium oxide (TiO x ) a metal oxide film. 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.

[0012] A light absorbing layer 16 is formed on the electron transport layer 15. The light absorbing layer 16 is a porous semiconductor layer formed by adsorbing a dye to an electron collector. The electron collector is, for example, a fine oxide semiconductor, such as titanium oxide (TiO 2) is an aggregate. The dye is, for example, a ruthenium (Ru) dye (RU) (such as N719 dye). The electron collector is not limited to titanium oxide, but may be, for example, zinc oxide, tin oxide, tungsten oxide, niobium oxide, indium oxide, or a complex thereof. 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, or the like may be used as pure organic dyes.

[0013] A catalyst layer 17 is formed on the counter electrode 14. The catalyst layer 17 is, for example, a platinum layer.

[0014] 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, etc. can be used. As a solute for the electrolyte solution 18, for example, iodine (I 2 ), 1,2-dimethyl-3-n-propylimidazolium iodide (DMPImI), lithium iodide (LiI), 4-tert-butylpyridine (TBP), and the like can be used.

[0015] A sealant 19 is formed between the electron transport layer 15 and the catalyst layer 17 at the outermost periphery of the dye-sensitized solar cell 1. The sealant 19 bonds the first substrate 11 and the second substrate 12 together and prevents the electrolyte 18 from leaking out. That is, the electrolyte 18 is sealed by the first substrate 11, the second substrate 12, and the sealant 19. The sealant 19 is, for example, a resin. The cell gap CG of the dye-sensitized solar cell 1 is determined by the diameter of the gap material contained in the sealant 19.

[0016] FIG. 2 is a diagram for explaining the power generation principle in the dye-sensitized solar cell 1. In the following example, the electron collector is titanium oxide (TiO 2 ), the dye is a ruthenium (Ru) dye, and the electrolyte 18 is an iodine (I) electrolyte.

[0017] First, when light is incident on the dye-sensitized solar cell, 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)

[0018] Electrons emitted from the excited dye 16a (e - ) is, for example, a porous titanium oxide (TiO 2 The electrons injected into the electron collector 16b move to the electrode 13, which is an anode electrode.

[0019] 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 ions (I 3 - The reaction formula is shown in the following formulas (2) and (3). Ru+e - →Ru (2) 3I - →I 3 - +2e - (3)

[0020] The triiodide ion (I 3 - ) is transported from the cathode electrode 14 to the counter electrode 14 by electrons (e - 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 (I 3 - ) is absorbed by the iodide ion (I 3- ) is the iodide ion (I - ) The reaction formula is shown, for example, in the following formula (4). I 3 - +2e - →3I - (4)

[0021] The above-mentioned redox reaction is repeated to generate electricity in the dye-sensitized solar cell unit. For this redox reaction to occur, the energy level of the excited dye 16a must be higher than the energy level of the electron collector 16b, and the energy level of the ground dye 16a must be lower than the energy level of the electrolyte 18.

[0022] One method for improving the output of a dye-sensitized solar cell is to increase the surface area of ​​the light absorbing layer 16. For example, TiO 2 The surface area of ​​the light absorbing layer 16, which is a layer, increases as the thickness of the layer increases. On the other hand, the increase in the thickness of the light absorbing layer 16 makes the light absorbing layer 16 more likely to peel off. If the light absorbing layer 16 peels off, the peeled light absorbing layer 16 will prevent the formation of a cell gap.

[0023] 3 is a diagram showing the relationship between the film thickness of the light absorbing layer 16 and the maximum output of the dye-sensitized solar cell 1. In FIG. 3, the light absorbing layer 16 is a TiO 2 The horizontal axis of Fig. 3 is the TiO 2 On the other hand, the maximum output on the vertical axis of Fig. 3 is the TiO 2 The maximum output is shown as a ratio, with the maximum output when the film thickness is 4 μm being taken as 1.

[0024] As shown in Figure 3, TiO 2 Up to a film thickness of about 10 μm, TiO 2 The maximum output increases with increasing film thickness. 2 When the film thickness becomes about 10 μm, the maximum output starts to decrease. This is because TiO 2 This means that peeling begins to occur when the film thickness is about 10 μm.2 The film thickness is preferably 10 μm or less.

[0025] In the embodiment, TiO 2 In order to increase the surface area of ​​the light absorbing layer 16 while maintaining the film thickness at 10 μm or less, TiO is used as an electron collector in the light absorbing layer 16. 2 The roughness factor (RF) is increased by reducing the particle diameter of the particles. The roughness factor is an index for evaluating surface roughness. For example, the roughness factor of the light absorbing layer 16 is a value of 1 or more calculated from the ratio of the surface area of ​​all particles in a plane P along the stacking direction of the light absorbing layer 16 to the occupied cross-sectional area of ​​one particle p of the light absorbing layer 16, as shown in FIG. 4. A large roughness factor indicates that the surface is rough, that is, the surface area is large. In the following, the roughness factor is shown with one particle approximated to be cubic rather than spherical.

[0026] Figure 5 shows TiO 2 FIG. 5 is a diagram showing an example of the relationship between the average particle size and the roughness factor when the film thickness is set to 10 μm. In FIG. 5, the roughness factor is shown when the average particle size is 14 nm, 16 nm, and 18 nm. As shown in FIG. 5, TiO 2 When the film thickness is 10 μm, if the average particle diameter is 14 nm, the roughness factor is 2244, if the average particle diameter is 16 nm, the roughness factor is 1963, and if the average particle diameter is 18 nm, the roughness factor is 1745. As can be seen from Figure 5, for the same TiO 2 In the case of film thickness, the smaller the average particle diameter, the larger the roughness factor.

[0027] FIG. 6 is a graph showing the relationship between the average particle size and the maximum output. Here, FIG. 6 shows the relationship between the average particle size and the maximum output when the cell gap is 15 μm and TiO 2The results are shown under the condition that the film thickness is 8 μm and the electrode size is 5 mm × 5 mm. The maximum output in FIG. 6 is shown as a ratio with the maximum output when the average particle diameter is 14 nm taken as 1. FIG. 6 also shows the results under illumination of 200 lux and under illumination of 30,000 lux. 200 lux is a low illumination condition assumed to be indoor lighting, and 30,000 lux is a high illumination condition assumed to be outdoor lighting. As shown in FIG. 6, it can be seen that when the average particle diameter is 18 nm, the maximum output decreases especially at high illumination. In other words, in order to prevent the power generation performance of the dye-sensitized solar cell 1 from decreasing even under high illumination, the average particle diameter should be 16 nm or less, that is, TiO 2 When the film thickness is 10 μm, the roughness factor is preferably about 2000 or less.

[0028] From the above, in the embodiment, TiO having an average particle size of 16 nm or less 2 Using TiO 2 A light absorbing layer 16 having a thickness of 10 μm is formed.

[0029] FIG. 7 is a flow chart showing an example of a method for manufacturing a dye-sensitized solar cell in an embodiment. In step S1, a cathode substrate is manufactured. The cathode substrate may be manufactured by any method. For example, a transparent conductive oxide film that will become the counter electrode 14 and a metal film that will become the catalyst layer are sequentially formed on a second substrate 12 such as a glass substrate. The transparent conductive oxide film is, for example, an ITO film. The metal film is, for example, a Pt film. The method for forming the transparent conductive oxide film and the metal film is not limited to a specific method. After the transparent conductive oxide film and the metal film are formed on the second substrate 12, a mask is formed on the metal film according to the shape of the counter electrode 14. Then, the transparent conductive oxide film is etched using an etching solution for the transparent conductive oxide film, for example, an ITO etching solution. When the metal film is formed as a thin film of, for example, 10 nm or less, the metal film can also be etched using an ITO etching solution. That is, in an embodiment, the transparent conductive oxide film and the metal film can be etched together by the ITO etching solution. After the etching of the transparent conductive oxide film is completed, the mask is removed. As a result, the counter electrode 14 and the catalyst layer 17 are formed on the second substrate 12. In this manner, the cathode substrate is manufactured. Here, the manufacture of the cathode substrate may be performed in parallel with the manufacture of the anode substrate described below.

[0030] In step S2, a transparent conductive oxide film that will become the electrode 13 is formed on a first substrate 11 such as a glass substrate. The transparent conductive oxide film is, for example, an ITO film. Then, in step S3, a metal oxide film that will become the electron transport layer 15 is formed on the transparent conductive oxide film. The metal oxide film is, for example, TiO xThe transparent conductive oxide film and the metal oxide film are formed by any method. After the transparent conductive oxide film and the metal oxide film are formed on the first substrate 11, a mask is formed on the metal oxide film according to the shape of the electrode 13. The transparent conductive oxide film is then etched using an etching solution for the transparent conductive oxide film, for example, an ITO etching solution. When the metal oxide film is formed as a thin film of, for example, 10 nm or less, the metal oxide film can also be etched using an ITO etching solution. That is, in the embodiment, the transparent conductive oxide film and the metal oxide film can be etched together by the ITO etching solution. After the etching of the transparent conductive oxide film is completed, the mask is removed. As a result, the electrode 13 and the electron transport layer 15 are formed on the first substrate 11.

[0031] In step S4, a layer of, for example, TiO 2 The paste is formed on the electron transport layer 15 by a method such as screen printing and dispensing. 2 The paste is TiO 2 The average particle size of the paste is 16 nm or less.

[0032] In step S5, TiO 2 The paste is sintered at a high temperature of 500-600 °C. The sintered substrate is then immersed in a dye solution to form TiO 2 In this way, the light absorbing layer 16 is formed.

[0033] In step S6, the first substrate 11 is coated with the sealing material 19 including a gap material for forming a cell gap of, for example, 15 μm.

[0034] In step S7, the electrolyte solution 18 is dropped onto the first substrate.

[0035] In step S8, the first substrate 11 and the second substrate 12 are bonded together via the sealing material 19. Thereafter, the sealing material 19 is cured, for example, by ultraviolet light irradiation. In this manner, the dye-sensitized solar cell is manufactured.

[0036] As described above, according to this embodiment, the dye-sensitized solar cell 1 having the light-absorbing layer 16 with a thickness of 10 μm using an electron collector with an average particle size of 16 nm or less does not experience a decrease in power generation performance due to peeling or the like, and does not experience a decrease in power generation performance even under high illuminance. In this way, a dye-sensitized solar cell with high power generation performance is obtained.

[0037] 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]

[0038] 1 dye-sensitized solar cell, 11 first substrate, 12 second substrate, 13 electrode, 14 counter electrode, 15 electron transport layer, 16 light absorption layer, 17 catalyst layer, 18 electrolyte, 19 sealing material.

Claims

1. An electrode formed on a first substrate; an electron transport layer formed on the electrode; a light absorbing layer formed on the electron transport layer and including an electron collector and a dye; a counter electrode formed on a second substrate disposed opposite the first substrate; A catalyst layer formed on the counter electrode; an electrolyte filled between the light absorbing layer and the catalyst layer; a sealant interposed between the first substrate and the second substrate, for sealing the electrode, the electron transport layer, the light absorbing layer, the counter electrode, the catalyst layer, and the electrolyte; Equipped with the thickness of the light absorbing layer is 10 μm or less, and the average particle size of the electron collector is 16 nm or less; Dye-sensitized solar cells.

2. The electron collector is TiO ２ is a particle, The dye-sensitized solar cell according to claim 1 .

3. The light absorbing layer has a roughness factor of 2000 or more. The dye-sensitized solar cell according to claim 1 .

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