Photoelectric conversion element and its manufacturing method

Abstract

A photoelectric conversion element and a method for manufacturing the same are provided. [Solution] The photoelectric conversion element 1 has a first substrate 11 having optical transparency, a first electrode 12 arranged on the first substrate 11, a photoelectric conversion layer 20 containing semiconductor microparticles and dye molecules, a second electrode 32 that is the counter electrode of the first electrode 12, a second substrate 31 facing the first substrate 11 at a distance, a sealant 70 arranged between the first substrate 11 and the second substrate 31, and a carrier transport material that fills the area surrounded by the sealant 70, and is provided on the second substrate 31 side with a catalyst layer 40 and a porous layer 50 provided in contact with the catalyst layer.

Description

[Technical Field]

[0001] The present disclosure relates to a photoelectric conversion element and a method for manufacturing the same. [Background technology]

[0002] Photoelectric conversion elements are used in, for example, optical sensors, copiers, solar cells, etc. Among these, solar cells are becoming increasingly popular as a representative method of utilizing renewable energy. Solar cells using inorganic photoelectric conversion elements (for example, silicon-based solar cells, CIGS-based solar cells, and CdTe-based solar cells) are widely used.

[0003] Solar cells using organic photoelectric conversion elements are also being considered, and dye-sensitized solar cells have also been proposed that utilize the photoinduced electron transfer of metal complexes, without using silicon substrates, which increase costs. In dye-sensitized solar cells, electrons are generated in the photoelectric conversion unit when irradiated with light, and the electrons that move to one electrode pass through an external electrical circuit, then are carried by ions in the electrolyte via the other opposing electrode and return to the photoelectric conversion unit, thereby extracting electrical energy.

[0004] For example, Patent Document 1 discloses that a photoelectrode is constructed by stacking a transparent electrode, a photoelectric conversion layer, and a light-reflecting layer in this order, with the photoelectric conversion layer being a porous semiconductor carrying a sensitizing dye, and the light-reflecting layer being a porous material not carrying a sensitizing dye. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-119189 Summary of the Invention [Problem to be solved by the invention]

[0006] In dye-sensitized solar cells, when a light-reflecting layer is laminated on a photoelectric conversion layer, the dye molecules of the photosensitizer are also adsorbed to the light-reflecting layer during the process of adsorbing them to the porous semiconductor, and electrons are also generated in the light-reflecting layer. However, the distance from the transparent electrode increases, which lengthens the extraction time and generates internal losses. This results in a decrease in photoelectric conversion efficiency, an increase in the amount of dye used, and reduced productivity.

[0007] Furthermore, suppressing the adsorption of dye molecules to the light-reflecting layer poses a problem of reduced productivity. For example, in the technology disclosed in Patent Document 1, a porous body not carrying a sensitizing dye is laminated on a photoelectric conversion layer, so it is necessary to prevent the light-reflecting layer from coming into contact with the sensitizing dye during dyeing, and the sensitizing dye must be carried on a porous semiconductor layer, and the photoelectric conversion layer must be formed in advance before the light-reflecting layer is formed.

[0008] The present disclosure has been made in consideration of the above-mentioned problems, and its purpose is to provide a photoelectric conversion element and a manufacturing method thereof that can improve at least one of the following: improved photoelectric conversion efficiency, reduced dye usage, and improved productivity. [Means for solving the problem]

[0009] The solution of the present disclosure for achieving the above-mentioned object is a photoelectric conversion element having a first substrate having optical transparency, a first electrode arranged on the first substrate, a photoelectric conversion layer arranged on the first electrode and containing semiconductor microparticles and dye molecules, a second electrode that serves as the counter electrode of the first electrode, a second substrate arranged on the second electrode and facing the first substrate at a distance, a sealant arranged between the first substrate and the second substrate, and a carrier transport material that fills the area surrounded by the first electrode, the second electrode, and the sealant, characterized in that the second substrate side includes a catalyst layer arranged in contact with the second electrode, and a porous layer arranged in contact with the catalyst layer and composed of microparticles of a material different from the microparticles that constitute the catalyst layer, and the photoelectric conversion layer and the porous layer are arranged facing each other at a distance.

[0010] In the photoelectric conversion element having the above configuration, the porous layer preferably has a reflectance greater than that of the photoelectric conversion layer.

[0011] In the photoelectric conversion element having the above configuration, the average particle size of the fine particles constituting the porous layer is preferably larger than the average particle size of the fine particles constituting the photoelectric conversion layer.

[0012] In the photoelectric conversion element having the above configuration, the average particle diameter of the fine particles constituting the porous layer is preferably 200 nm or more and 500 nm or less.

[0013] In the photoelectric conversion element having the above configuration, the distance between the photoelectric conversion layer and the porous layer is preferably 0.1 μm or more and 100 μm or less.

[0014] Furthermore, the method for manufacturing a photoelectric conversion element according to each of the above-described solutions also falls within the scope of the technical idea of ​​the present disclosure. That is, a method for manufacturing a photoelectric conversion element having a first substrate having optical transparency, a first electrode disposed on the first substrate, a photoelectric conversion layer disposed on the first electrode and comprising semiconductor particles and dye molecules, a second electrode serving as the counter electrode of the first electrode, a second substrate disposed on the second electrode and facing the first substrate at a distance, a sealant disposed between the first substrate and the second substrate, and a carrier transport material filling the area surrounded by the first electrode, the second electrode, and the sealant, characterized in that the method includes a first substrate side formation process of forming the photoelectric conversion layer on the first substrate having the first electrode, a second substrate side formation process of forming a catalyst layer and a porous layer in contact with the catalyst layer on the second substrate having the second electrode, and a process of bonding the first substrate and the second substrate together via the sealant after the first substrate side formation process and the second substrate side formation process, so that the photoelectric conversion layer and the porous layer face each other.

[0015] In the method for manufacturing a photoelectric conversion element, the first substrate side forming step may include a dye printing step of laminating the dye molecules on the semiconductor fine particles by a printing method. [Effects of the Invention]

[0016] According to the present disclosure, it is possible to improve at least one of the following: improvement in photoelectric conversion efficiency, reduction in the amount of dye used, and improvement in productivity. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view schematically illustrating a photoelectric conversion element according to a first embodiment of the present disclosure. [Figure 2] 1 is a flowchart illustrating an example of a method for manufacturing a photoelectric conversion element. [Figure 3] 10 is a flowchart showing another example of a method for manufacturing a photoelectric conversion element. [Figure 4] FIG. 3 is a cross-sectional view schematically illustrating a photoelectric conversion element according to a second embodiment of the present disclosure. [Figure 5] 1 is a flowchart illustrating an example of a method for manufacturing a photoelectric conversion element. [Figure 6] 10 is a flowchart showing another example of a method for manufacturing a photoelectric conversion element. DETAILED DESCRIPTION OF THE INVENTION

[0018] A photoelectric conversion element and a manufacturing method thereof according to an embodiment of the present disclosure will be described with reference to the drawings.

[0019] [Embodiment 1] Photoelectric conversion element 1 is a cross-sectional view schematically illustrating a photoelectric conversion element 1 according to a first embodiment of the present disclosure. In the following description and drawings, the same reference symbols indicate the same or corresponding parts. Furthermore, dimensional relationships such as length, width, thickness, and depth in the drawings have been appropriately changed for clarity and simplification of the drawings, and do not represent actual dimensional relationships.

[0020] The photoelectric conversion element 1 includes an electrode substrate 10 including a first substrate 11 and a first electrode 12 disposed on the first substrate 11, a photoelectric conversion layer 20 disposed on the first electrode 12, a counter electrode substrate 30 including a second electrode 32 serving as a counter electrode of the first electrode 12 and a second substrate 31 disposed on the second electrode 32, a sealant 70, and an electrolyte solution 60 containing a carrier transport material. A catalyst layer 40 in contact with the second electrode 32 and a porous layer 50 in contact with the catalyst layer 40 are provided on the counter electrode substrate 30 side. The electrolyte solution 60 is filled not only in the photoelectric conversion layer 20 but also in the voids in the porous layer 50 and the catalyst layer 40. The components constituting the photoelectric conversion element 1 are described below.

[0021] (First board) The electrode substrate 10 has a first substrate 11 and a first electrode 12. The first substrate 11 is a support made of a light-transmitting material, and is a light-transmitting substrate whose light-receiving surface is light-transmitting. However, the first substrate 11 does not necessarily need to be transparent to light in all wavelength ranges, as long as it is made of a material that substantially transmits light of a wavelength to which the dye molecules described below have effective sensitivity. The first substrate 11 preferably has a thickness of 0.2 mm or more and 5 mm or less.

[0022] The first substrate 11 is not particularly limited as long as it is made of a material generally used in solar cells, and can be a glass substrate such as soda glass, fused silica glass, or crystalline quartz glass, a heat-resistant plastic plate such as a flexible film, etc. Examples of flexible films include tetraacetyl cellulose (TAC), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polycarbonate (PC), polyarylate (PA), polyetherimide (PEI), phenoxy resin, and Teflon (registered trademark).

[0023] (1st electrode) The first electrode 12 is a transparent conductive layer formed on the first substrate 11. The first electrode 12 is preferably formed from a material that is substantially transparent to light of a wavelength to which the dye molecules described below have effective sensitivity, but does not necessarily have to be transparent to light in all wavelength ranges. Examples of such materials include indium tin oxide (ITO), tin oxide (SnO), fluorine-doped tin oxide (FTO), zinc oxide (ZnO), and titanium oxide doped with tantalum or niobium.

[0024] The first electrode 12 can be formed as a thin film on the first substrate 11 by a known method such as sputtering or spraying. The film thickness of the first electrode 12 is preferably 0.02 μm or more and 5 μm or less. The film resistance of the first electrode 12 is preferably 40 Ω / sq or less, and the lower the better.

[0025] (Photoelectric conversion layer) The photoelectric conversion layer 20 is a light-absorbing layer comprising a porous semiconductor carrying dye molecules, allowing the carrier transport material (described later) to move within and outside the layer. The porous semiconductor constituting the photoelectric conversion layer 20 is semiconductor fine particles, and the type is not particularly limited as long as it is a semiconductor commonly used in photoelectric conversion materials. Examples of such semiconductors include at least one selected from titanium oxide, zinc oxide, tin oxide, iron oxide, niobium oxide, cerium oxide, tungsten oxide, barium titanate, strontium titanate, cadmium sulfide, lead sulfide, zinc sulfide, indium phosphide, copper-indium sulfide (CuInS2), CuAlO2, and SrCu2O2, and combinations thereof can also be used. Among these, titanium oxide is particularly preferred for the photoelectric conversion layer 20 from the standpoints of stability and safety.

[0026] Examples of titanium oxides suitable for use as porous semiconductors include various titanium oxides in the narrow sense, such as anatase titanium oxide, rutile titanium oxide, amorphous titanium oxide, metatitanic acid, and orthotitanic acid, as well as titanium hydroxide, titanium hydroxide, and hydrous titanium oxide, which can be used alone or in combination of two or more. The two types of crystalline titanium oxide, anatase titanium oxide and rutile titanium oxide, can take either form depending on their production method and thermal history, but the titanium oxide constituting the porous semiconductor preferably has a high content of anatase titanium oxide, and more preferably contains 80% or more anatase titanium oxide.

[0027] The porous semiconductor may be formed as either a single crystal or a polycrystal. From the viewpoints of stability, ease of crystal growth, manufacturing costs, etc., the porous semiconductor is preferably a polycrystal. Furthermore, the porous semiconductor is preferably composed of nanoscale to microscale semiconductor particles, and more preferably titanium oxide particles are used.

[0028] Titanium oxide fine particles can be produced by known methods such as gas phase methods and liquid phase methods (hydrothermal synthesis, sulfuric acid method), etc. Titanium oxide fine particles can also be obtained by high-temperature hydrolysis of chlorides, which was developed by Degussa.

[0029] The semiconductor particles constituting the photoelectric conversion layer 20 may be semiconductor compounds of the same composition, or a mixture of two or more semiconductor compounds of different compositions. It is believed that semiconductor particles with a large particle size contribute to improving light absorption by scattering incident light, while semiconductor particles with a small particle size contribute to improving the amount of dye molecule adsorption by increasing the surface area. Therefore, it is preferable that the particle size of the photoelectric conversion layer 20 be smaller than that of the porous layer 50 described below.

[0030] The particle diameter can be measured by observing the cross section of the photoelectric conversion element 1 using a scanning electron microscope (SEM) or the like. Therefore, the "particle diameter" refers to the primary particle diameter measured based on a two-dimensional image observed with a scanning electron microscope (SEM).

[0031] The semiconductor particles constituting the photoelectric conversion layer 20 have an average particle diameter of 5 nm to 100 nm, preferably 10 nm to 50 nm. In particular, semiconductor particles with an average particle diameter of approximately 20 nm to 30 nm can increase the number of adsorption sites and contribute to improving the amount of dye molecules adsorbed.

[0032] Two or more types of semiconductor particles with different particle sizes may be mixed to form the porous semiconductor of the photoelectric conversion layer 20. When two or more types of semiconductor particles are mixed, it is effective to use semiconductor particles with small particle sizes of semiconductor compounds with strong adsorption properties.

[0033] The thickness of the photoelectric conversion layer 20 is not particularly limited, but is preferably, for example, 0.1 μm or more and 100 μm or less. The photoelectric conversion layer 20 preferably has a large surface area, and the specific surface area is preferably, for example, 10 m 2 / g or more 500m 2 The porosity of the photoelectric conversion layer 20 is preferably, for example, 40% or more and 75% or less.

[0034] (Sensitizing dye) Dye molecules are supported on the porous semiconductor of the photoelectric conversion layer 20. The dye molecules are sensitizing dyes that convert light energy incident on the photoelectric conversion element 1 into electrical energy. Note that FIG. 1 shows the sensitizing dye denoted by reference numeral 80 supported on the photoelectric conversion layer 20. As the sensitizing dye, one or more dye molecules can be selectively used from various organic dyes and metal complex dyes that have absorption in the visible light region or infrared light region.

[0035] Examples of organic dyes include azo dyes, quinone dyes, quinoneimine dyes, quinacridone dyes, squarylium dyes, cyanine dyes, merocyanine dyes, triphenylmethane dyes, xanthene dyes, porphyrin dyes, perylene dyes, indigo dyes, naphthalocyanine dyes, etc. The absorption coefficient of an organic dye is generally larger than that of a metal complex dye in which a molecule is coordinately bonded to a transition metal.

[0036] Metal complex dyes are dyes in which a transition metal is coordinately bonded to a metal atom. Examples of such metal complex dyes include porphyrin dyes, phthalocyanine dyes, naphthalocyanine dyes, and ruthenium dyes. Examples of metal atoms constituting metal complex dyes include Cu, Ni, Fe, Co, V, Sn, Si, Ti, Ge, Cr, Zn, Ru, Mg, Al, Pb, Mn, In, Mo, Y, Zr, Nb, Sb, La, W, Pt, Ta, Ir, Pd, Os, Ga, Tb, Eu, Rb, Bi, Se, As, Sc, Ag, Cd, Hf, Re, Au, Ac, Tc, Te, and Rh. Among these, metal complex dyes in which a metal is coordinated to a phthalocyanine dye or a ruthenium dye are preferred, and ruthenium metal complex dyes are particularly preferred.

[0037] As the Ru metal complex dye, for example, commercially available Ru metal complex dyes such as Ruthenizer 535 dye, Ruthenizer 535-bisTBA dye, or Ruthenizer 620-1H3TBA dye, which are trade names of Solaronix, can be used.

[0038] The photoelectric conversion layer 20 may be supported with a co-adsorbent. The co-adsorbent suppresses association and aggregation of the dye molecules, allowing the dye molecules to be adsorbed in a uniformly dispersed state in the porous semiconductor layer. The co-adsorbent can be appropriately selected from materials commonly used in the field in accordance with the dye molecules to be combined.

[0039] (Second board) The counter electrode substrate 30 includes a second substrate 31 and a second electrode 32. The second substrate 31 preferably has a thickness of 0.2 mm to 5 mm. Like the first substrate 11, the second substrate 31 is not particularly limited as long as it is made of a material commonly used in solar cells. Examples of suitable materials include glass substrates such as soda glass, fused silica glass, and crystalline quartz glass, and heat-resistant plastic plates such as flexible films. Examples of flexible films include tetraacetyl cellulose (TAC), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polycarbonate (PC), polyarylate (PA), polyetherimide (PEI), phenoxy resin, and Teflon (registered trademark). The second substrate 31 may be selected so as to sufficiently transmit light having a wavelength required for curing the sealing material 70 (described later).

[0040] (2nd electrode) The second electrode 32 is a counter electrode conductive layer having translucency and conductivity that is laminated on the second substrate 31. The second electrode 32 can have the same configuration as the first electrode 12 on the first substrate 11.

[0041] (catalyst layer) A catalyst layer 40 and a porous layer 50 are provided on the counter electrode substrate 30 side. The catalyst layer 40 is provided in contact with the second electrode 32, and enables efficient transfer of electrons to and from the second electrode 32. The catalyst layer 40 contains fine particles with catalytic activity. There are no particular limitations on the method for laminating the catalyst layer 40, and it can be screen printing, vapor deposition, sputtering, or the like.

[0042] The fine particles constituting the catalyst layer 40 are not limited as long as they are made of a material that allows electron transfer on the surface of the catalyst layer 40, but are preferably, for example, platinum (Pt), palladium or other noble metal materials, carbon black, Ketjen black or other carbon-based materials, or conductive polymer materials. The conductive polymer material may be, for example, PEDPT or PEDOT:PSS. Platinum can be formed by methods such as sputtering, thermal decomposition of chloroplatinic acid, or electrodeposition. From the viewpoint of minimizing the amount of expensive platinum used, platinum formed by thermal decomposition of chloroplatinic acid is particularly preferred.

[0043] (porous layer) The porous layer 50 is provided in contact with the catalyst layer 40 and is configured to reflect light that has passed through the photoelectric conversion layer 20 and allow it to re-enter the photoelectric conversion layer 20. The porous layer 50 is made of fine particles. When light hits the fine particles, it is scattered, so the porous layer 50 made of fine particles functions as a reflective layer. The porous layer 50 is configured as a reflective layer with a higher reflectance than the photoelectric conversion layer 20. The porous layer 50 can have a higher reflectance than the photoelectric conversion layer 20 by using fine particles with a larger particle diameter than the semiconductor fine particles that make up the photoelectric conversion layer 20.

[0044] In the photoelectric conversion element 1 according to the present disclosure, the porous layer 50 is composed of fine particles of a material different from the fine particles that compose the catalyst layer 40. For example, the porous layer 50 is a porous oxide layer formed using fine particles of a metal oxide. The porous layer 50 is preferably formed using a material that can reflect light, and for example, semiconductor fine particles such as titanium oxide, aluminum oxide, or barium titanate can be used. In particular, it is more preferable that the porous layer 50 contains aluminum oxide or titanium oxide.

[0045] Furthermore, the porous layer 50 contains a high proportion of fine particles having a larger average particle diameter than the semiconductor fine particles that constitute the photoelectric conversion layer 20, and more preferably, the porous layer 50 is composed only of fine particles having a larger average particle diameter than the semiconductor fine particles of the photoelectric conversion layer 20. Therefore, the average particle diameter of the fine particles that constitute the porous layer 50 is larger than the average particle diameter of the fine particles that constitute the photoelectric conversion layer 20.

[0046] The average particle diameter of the fine particles constituting the porous layer 50 is set to 200 nm or more and 1000 nm or less, which is larger than the average particle diameter of the fine particles constituting the photoelectric conversion layer 20 .

[0047] The porous layer 50 is provided facing the photoelectric conversion layer 20 without contacting the photoelectric conversion layer 20. The porous layer 50 and the photoelectric conversion layer 20 are layers provided facing each other, but if they were to come into contact with each other, it would cause a short circuit. For this reason, the photoelectric conversion layer 20 and the porous layer 50 are provided in a spaced-apart state, and although a carrier transport material exists between them, they are provided facing each other with a physical space interposed therebetween.

[0048] The thickness of the porous layer 50 is preferably 1 μm or more and 100 μm or less. If the thickness of the porous layer 50 is 1 μm or less, the light reflectance may decrease, and if it is 100 μm or more, the porous layer 50 and the photoelectric conversion layer 20 may come into contact with each other, which is not preferable.

[0049] Increasing the space between the photoelectric conversion layer 20 and the porous layer 50 may result in increased costs due to an increase in the amount of carrier transport material, increased internal loss due to carrier transport resistance, and increased internal loss due to light absorption in the carrier transport material due to an increase in the optical path length of reflected light.

[0050] Therefore, the mutual distance between the surface of the photoelectric conversion layer 20 and the surface of the porous layer 50 is preferably 0.1 μm or more and 100 μm or less, and more preferably 5 μm or more and 70 μm or less, which makes it possible to reduce the amount of carrier transport material used, suppress cost increases, and suppress internal loss due to carrier transport resistance.

[0051] By providing such a porous layer 50, reflected light is incident on the photoelectric conversion layer 20, thereby improving photoelectric conversion efficiency. Furthermore, because the porous layer 50 is formed by laminating it on the second substrate 31, it is easy to make the dye only supported in the porous semiconductor formed on the first substrate 11. Even if the dye is adsorbed to the porous layer 50, the porous layer 50 is not formed in contact with the photoelectric conversion layer 20, so a decrease in photoelectric conversion efficiency is suppressed. Specifically, when a light-reflecting layer is laminated on the photoelectric conversion layer, electrons are generated in the light-reflecting layer due to the dye adsorbed to the light-reflecting layer. However, the distance from the transparent electrode increases, which increases the extraction time and generates internal loss, resulting in a decrease in photoelectric conversion efficiency. However, because the porous layer 50 is not in contact with the photoelectric conversion layer 20, such problems do not occur.

[0052] (Sealing material) A sealant 70 is disposed between the electrode substrate 10 and the counter electrode substrate 30. The sealant is provided to join the electrode substrate 10, which includes the first substrate 11 and the first electrode 12, to the counter electrode substrate 30, which includes the second substrate 31 and the second electrode 32.

[0053] For example, a material containing at least one selected from the group consisting of silicone resin, acrylic resin, epoxy resin, polyisobutylene resin, hot melt resin, and glass-based resin such as glass frit can be used for the sealing material 70. Furthermore, it is preferable to use an ultraviolet-curable resin material for the sealing material 70, as it has a fast curing speed and reduces working time.

[0054] (Carrier transport material) The region surrounded by the electrode substrate 10, the counter electrode substrate 30, and the sealing material 70 is filled with an electrolyte solution 60 containing a carrier transport material. The electrolyte solution 60 also fills the voids in the photoelectric conversion layer 20, the porous layer 50, and the catalyst layer 40. The carrier transport material is preferably a conductive material capable of transporting ions, and is preferably, for example, a liquid electrolyte, a solid electrolyte, a gel electrolyte, or a molten salt gel electrolyte.

[0055] The liquid electrolyte is preferably a liquid containing redox species, and is not particularly limited as long as it can generally be used in batteries, solar cells, etc. Specifically, the liquid electrolyte is preferably one consisting of a redox species and a solvent capable of dissolving the redox species, one consisting of a redox species and a molten salt capable of dissolving the redox species, or one consisting of a redox species, the solvent, and the molten salt.

[0056] The redox species include, for example, I - / I 3- system, Br 2- / Br 3- system, Fe 2+ / Fe 3+ system, Co 2+ / Co 3+ system, Cu + / Cu 2+ Examples of such compounds include quinone / hydroquinone systems.

[0057] Examples of solvents for redox species include carbonate solvents such as propylene carbonate, nitrile solvents such as acetonitrile, alcohol solvents such as ethanol, and lactone solvents such as γ-butyrolactone. Two or more of these solvents can also be mixed and used. The viscosity and electrolyte solubility of the solvent are preferably selected comprehensively depending on the temperature environment in which the DSSC is installed, etc.

[0058] Such a photoelectric conversion element 1 is configured to improve the light scattering effect of the porous layer 50 and increase the photoelectric conversion efficiency. In the photoelectric conversion element 1 according to this embodiment, both the photoelectric conversion layer 20 on the first electrode 12 side and the porous layer 50 on the second electrode 32 side can be said to be porous semiconductor layers, but the particles constituting the porous layer 50 do not have to be semiconductor particles, and are not limited to the exemplified particles as long as they are particles having the reflectivity to reflect light that has passed through the photoelectric conversion layer 20 and allow it to be incident on the photoelectric conversion layer 20 again.

[0059] Photoelectric conversion element manufacturing method FIG. 2 is a flowchart showing an example of a method for manufacturing the photoelectric conversion element 1 according to the first embodiment.

[0060] The manufacturing method of the photoelectric conversion element 1 according to the embodiment can be broadly divided into a first substrate side formation process (steps S11 to S14) including a process of forming a photoelectric conversion layer 20 on a first substrate 11 having a first electrode 12, a second substrate side formation process (steps S21 to S22) including a process of forming a catalyst layer 40 and a porous layer 50 on a second substrate 31 having a second electrode 32, and a bonding process (steps S31 to S32) in which the electrode substrate 10 and counter electrode substrate 30 that have undergone these processes are bonded together facing each other with a gap between them and cured.

[0061] (First substrate side formation process) More specifically, in the first substrate side formation step, the first electrode 12 is formed on the first substrate 11 to obtain the electrode substrate 10 (step S11). Next, a porous semiconductor that constitutes the photoelectric conversion layer 20 is formed on the first electrode 12 (step S12).

[0062] The method for forming a porous semiconductor on the first electrode 12 is not particularly limited, but for example, a suspension of semiconductor particles suspended in an appropriate solvent is applied to the first electrode 12, and the suspension is then dried and / or baked to form a porous semiconductor on the first electrode 12.

[0063] Examples of solvents used in the suspension include glyme-based solvents such as ethylene glycol monomethyl ether, alcohols such as isopropyl alcohol, mixed alcohol solvents such as isopropyl alcohol / toluene, water, etc. Alternatively, commercially available titanium oxide pastes (e.g., Ti-nanoxide, T, D, T / SP, D / SP manufactured by Solaronix) may be used instead of such suspensions.

[0064] The suspension can be applied by any known method such as a doctor blade method, a squeegee method, a spin coating method, or a screen printing method.

[0065] The conditions (temperature, time, atmosphere, etc.) required for drying and firing the porous semiconductor may be set appropriately depending on the type of semiconductor particles, and for example, when drying and firing in air or an inert gas atmosphere, it is preferable to carry out the drying and firing for about 10 seconds to 12 hours at a temperature in the range of about 50 to 800° C. This drying and firing may be carried out once at a single temperature or two or more times at different temperatures.

[0066] The porous semiconductor may be a laminate of multiple layers. To laminate the porous semiconductor, it is preferable to prepare suspensions of different semiconductor particles and repeat at least one of the steps of coating, drying, and firing two or more times.

[0067] After forming the porous semiconductor, it is preferable to perform post-treatment to improve the performance of the porous semiconductor. By performing post-treatment on the porous semiconductor, it is possible to improve the electrical connection between semiconductor particles, increase the surface area of ​​the porous semiconductor, and reduce defect levels on the semiconductor particles. For example, the performance of the porous semiconductor can be improved by post-treating a porous semiconductor made of titanium oxide with an aqueous titanium tetrachloride solution.

[0068] Next, a sealant 70 is placed on the electrode substrate 10 on which the porous semiconductor has been formed (step S13). In this case, the sealant 70 (more specifically, at this stage, it is a precursor of the sealant 70, meaning a resin material before hardening) is placed in a frame shape surrounding the porous semiconductor on the first electrode 12 on the first substrate 11. There are no particular limitations on the method for placing the sealant 70, but it can be placed by a coating method, for example.

[0069] Next, a dye electrolyte solution is dropped onto the porous semiconductor within the frame of the sealing material 70 on the electrode substrate 10 (step S14). The amount of dye electrolyte solution dropped can be the same as the amount that is ultimately sealed within the photoelectric conversion element 1. The dye electrolyte solution can be one in which a sensitizing dye is dissolved in an electrolyte solution containing a carrier transport material. This allows the dye molecules in the dye electrolyte solution to be adsorbed onto the porous semiconductor. A photoelectric conversion layer 20 made of a porous semiconductor supporting dye molecules can be formed on the electrode substrate 10, and the frame of the sealing material 70 can be filled with a dye electrolyte solution containing a carrier transport material.

[0070] (Second substrate side formation process) On the other hand, in the second substrate side formation step, a second electrode 32 is formed on a second substrate 31 to obtain a counter electrode substrate 30 (step S21). Next, a catalyst layer 40 and a porous layer 50 are formed on the second electrode 32 (step S22). More specifically, the catalyst layer 40 is formed on the second electrode 32 of the counter electrode substrate 30, and the porous layer 50 is further formed on the catalyst layer 40. The porous layer 50 can be formed using a method similar to the above-described method for forming a porous semiconductor that does not support dye molecules.

[0071] (Joining process) Next, the electrode substrate 10 obtained in the first substrate side forming step and the counter electrode substrate 30 obtained in the second substrate side forming step are bonded together (step S31). In this case, the counter electrode substrate 30 is placed on the electrode substrate 10 so that the porous layer 50 faces the photoelectric conversion layer 20 on the electrode substrate 10.

[0072] Next, the electrode substrate 10 and the counter electrode substrate 30 are bonded to each other via the sealing material 70. If the sealing material 70 is an ultraviolet-curable resin material, the sealing material 70 is cured by irradiating it with ultraviolet (UV) rays, and the electrode substrate 10 and the counter electrode substrate 30 are bonded together (step S32). If the sealing material 70 is a thermosetting resin material, the sealing material 70 is cured by applying heat.

[0073] As a result, the electrode substrate 10 and the counter electrode substrate 30 are bonded to each other and integrated via the sealing material 70. The photoelectric conversion layer 20 on the electrode substrate 10 side and the porous layer 50 on the counter electrode substrate 30 side are arranged facing each other, and the photoelectric conversion element 1 can be produced.

[0074] (Variation) Fig. 3 is a flowchart showing another example of the method for manufacturing the photoelectric conversion element 1 according to embodiment 1. As a modification of the method for manufacturing the photoelectric conversion element 1 described above, the first substrate side forming step may be performed by steps S41 to S46, as shown in Fig. 3. The second substrate side forming step (steps S21 to S22) and the bonding step (steps S31 to S32) are common to the above-described manufacturing method.

[0075] In this case, step S41 of forming a first electrode 12 on a first substrate 11 to obtain an electrode substrate 10, and step S42 of forming a porous semiconductor on the first electrode 12 can be performed in the same manner as in the above-mentioned manufacturing method.

[0076] Next, the dye solution is dropped onto the porous semiconductor on the first electrode 12 (step S43). The solvent for the dye solution may be any solvent that can dissolve the sensitizing dye, and examples thereof include alcohols such as ethanol, ketones such as acetone, ethers such as diethyl ether and tetrahydrofuran, cyclic esters such as γ-butyrolactone and ε-caprolactone, cyclic amides such as 1-methyl-2-pyrrolidone, and water. Two or more types of solvents can also be mixed and used.

[0077] It is preferable to drip the dye solution so that it does not adhere to the first electrode 12 around the porous semiconductor, and the surface of the first electrode 12 may be made water-repellent, or the periphery of the porous semiconductor may be covered with a sealant before the dripping step. It is also preferable to drip the dye solution in an amount equivalent to the volume of the porous semiconductor.

[0078] Next, the dropped dye solution is impregnated into the porous semiconductor, and the porous semiconductor is then dried (step S44). The sensitizing dye in the dye solution is adsorbed onto the porous semiconductor, and the porous semiconductor together with the electrode substrate 10 is vacuum dried or heat dried. This dries the dye solution. In the case of heat drying, it is preferable to heat at, for example, about 50°C. It is also preferable to perform a rinsing process to wash away and remove excess dye adhering to the surface of the dried porous semiconductor.

[0079] Next, a precursor of the sealant 70 is placed on the first electrode 12 of the electrode substrate 10 in a frame shape surrounding the photoelectric conversion layer 20 (step S45). Next, an electrolyte solution 60 containing a carrier transport material is dropped into the frame of the placed sealant 70 (step S46). The amount of the electrolyte solution can be the same as the amount that will ultimately be sealed in the photoelectric conversion element 1. In this way, a photoelectric conversion layer 20 made of a porous semiconductor carrying dye molecules is formed on the electrode substrate 10, and the frame of the sealant 70 can be filled with the electrolyte solution 60 containing the carrier transport material.

[0080] As described above, according to the manufacturing method of embodiment 1, a photoelectric conversion element 1 can be obtained in which the photoelectric conversion layer 20 on the electrode substrate 10 side and the porous layer 50 on the counter electrode substrate 30 side are arranged facing each other. In the obtained photoelectric conversion element 1, reflected light is incident on the photoelectric conversion layer 20, which enables to increase the photoelectric conversion efficiency, and also reduces the amount of carrier transport material used, thereby suppressing cost increases and making it possible to suppress the occurrence of internal losses due to carrier transport resistance.

[0081] The method of forming the photoelectric conversion layer 20 by adsorbing dye molecules to the porous semiconductor is not limited to the method of dropping the dye solution, but may also be, for example, a method of immersing the electrode substrate 10 on which the porous semiconductor has been formed in the dye solution and leaving it to stand for a long period of time.

[0082] [Embodiment 2] In the second embodiment, an example will be described in which a different method for manufacturing the photoelectric conversion element 1 is applied. Fig. 4 is a cross-sectional view schematically showing a method for manufacturing the photoelectric conversion element 1 according to the second embodiment.

[0083] In the manufacturing method of this embodiment, as shown in Figure 4, dye molecules (sensitizing dye indicated by symbol 80) are laminated and adsorbed on the photoelectric conversion layer 20, and the dye molecules are not supported on the microparticles that make up the porous layer 50.

[0084] FIG. 5 is a flowchart showing an example of a method for manufacturing the photoelectric conversion element 1 according to the second embodiment, and FIG. 6 is a flowchart showing another example of a method for manufacturing the photoelectric conversion element according to the second embodiment.

[0085] In this case, the feature is the first substrate side formation process (steps S51 to S56 / steps S61 to S66) which includes the process of forming a photoelectric conversion layer 20 on a first substrate 11 having a first electrode 12, and the second substrate side formation process (steps S21 to S22) and the process of joining the electrode substrate 10 and the counter electrode substrate 30 (steps S31 to S32) are common to embodiment 1.

[0086] 5, the first substrate side formation step is configured to include a dye printing step (step S53) of laminating dye molecules on semiconductor particles by a printing method. That is, after step S51 of forming a first electrode 12 on a first substrate 11 to obtain an electrode substrate 10 and step S52 of forming a porous semiconductor on the first electrode 12, the first substrate side formation step includes a step of printing a dye-containing paste on the porous semiconductor to adsorb the sensitizing dye only to the photoelectric conversion layer 20. The dye-containing paste may be a paste obtained by mixing a sensitizing dye with a solvent such as ethyl cellulose or terpineol.

[0087] In the dye printing step (step S53), dye molecules are selectively adsorbed onto the porous semiconductor. At the time of printing the dye-containing paste, some of the dye molecules are adsorbed onto the semiconductor particles of the porous semiconductor.

[0088] Next, the porous semiconductor is dried (step S54), and a sealant 70 is placed on the first electrode 12 of the electrode substrate 10 in a frame shape surrounding the photoelectric conversion layer 20 (step S45). Next, an electrolyte solution containing a carrier transport material is dropped into the frame of the placed sealant 70 (step S46). A photoelectric conversion layer 20 made of a porous semiconductor carrying dye molecules is formed on the electrode substrate 10, and the frame of the sealant 70 is filled with an electrolyte solution 60 containing a carrier transport material. Adsorption of the dye molecules printed in the dye printing step (step S53) further progresses with the dropping of the electrolyte solution 60. This makes it possible to selectively adsorb the sensitizing dye to the photoelectric conversion layer 20.

[0089] As a method for selectively adsorbing a sensitizing dye into a porous semiconductor, a dipping method may be used in addition to a printing method. For example, instead of the dye printing step (step S53) shown in Fig. 5, a step (step S63) of dipping the porous semiconductor into a dye solution (e.g., squeeze oil pump solution) in which a sensitizing dye has been dissolved may be performed as shown in Fig. 6. In this case, the dye solution may be heated to allow it to penetrate deep into the micropores in the porous semiconductor.

[0090] The solvent for dissolving the dye is not particularly limited as long as it dissolves the dye, and for example, a solvent containing at least one selected from the group consisting of alcohol, toluene, acetonitrile, tetrahydrofuran (THF), chloroform, and dimethylformamide can be used. It is preferable to use a purified solvent for dissolving the dye, and it is preferable to use a mixture of two or more types.

[0091] The dye concentration in the dye solution can be appropriately set depending on the conditions of the dye, the type of solvent, the dye printing process, etc., but a high concentration is preferable to improve the adsorption function, and it is generally 1×10 -5 It is preferably mol / liter or more.

[0092] In the photoelectric conversion element 1 shown in the second embodiment, the sensitizing dye is selectively adsorbed to the photoelectric conversion layer 20, thereby suppressing the adsorption of dye molecules to the porous layer 50 of the counter electrode substrate 30, and making it possible to reduce the amount of dye used. Furthermore, as in the first embodiment, the photoelectric conversion layer 20 on the electrode substrate 10 side and the porous layer 50 on the counter electrode substrate 30 side are not stacked but are arranged facing each other in the photoelectric conversion element 1. This allows reflected light to be incident on the photoelectric conversion layer 20, thereby increasing the photoelectric conversion efficiency, reducing the amount of carrier transport material used, suppressing cost increases, and making it possible to suppress the occurrence of internal loss due to carrier transport resistance.

[0093] Furthermore, by providing a dye-sensitized solar cell with the photoelectric conversion element 1 according to the configuration of the present disclosure, it is possible to provide a dye-sensitized solar cell having higher photoelectric conversion efficiency than conventional dye-sensitized solar cells.

[0094] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the technical gist thereof, and all technical matters included in the technical ideas described in the claims are the subject of the present disclosure. The above-described embodiments are preferred examples, but various modifications can be realized from the disclosed contents, and such modifications are also included in the technical scope described in the claims. [Explanation of symbols]

[0095] 1 Photoelectric conversion element 10 Electrode substrate 11 First board 12 1st electrode 20 Photoelectric conversion layer 30 Counter electrode substrate 31 Second board 32 2nd electrode 40 Catalyst layer 50 Porous layer 60 Electrolyte (carrier transport material) 70 Encapsulating material 80 Sensitizing dyes (dye molecules)

Claims

1. a first substrate having optical transparency; a first electrode disposed on the first substrate; a photoelectric conversion layer disposed on the first electrode and including semiconductor particles and dye molecules; a second electrode that is a counter electrode of the first electrode; a second substrate disposed on the second electrode and facing the first substrate with a gap therebetween; a sealant disposed between the first substrate and the second substrate; A photoelectric conversion element having the first electrode, the second electrode, and a carrier transport material filling a region surrounded by the sealing material, On the second substrate side, a catalyst layer provided in contact with the second electrode; a porous layer provided in contact with the catalyst layer and made of fine particles of a material different from the fine particles constituting the catalyst layer, The photoelectric conversion element is characterized in that the photoelectric conversion layer and the porous layer are provided facing each other with a space therebetween.

2. The photoelectric conversion element according to claim 1 , The photoelectric conversion element is characterized in that the porous layer has a reflectance greater than that of the photoelectric conversion layer.

3. The photoelectric conversion element according to claim 1 , A photoelectric conversion element, wherein the average particle size of the fine particles constituting the porous layer is larger than the average particle size of the fine particles constituting the photoelectric conversion layer.

4. The photoelectric conversion element according to claim 3 , The photoelectric conversion element is characterized in that the average particle diameter of the fine particles constituting the porous layer is 200 nm or more and 500 nm or less.

5. The photoelectric conversion element according to any one of claims 1 to 4, The photoelectric conversion element is characterized in that the mutual distance between the photoelectric conversion layer and the porous layer is 0.1 μm or more and 100 μm or less.

6. a first substrate having optical transparency; a first electrode disposed on the first substrate; a photoelectric conversion layer disposed on the first electrode and including semiconductor particles and dye molecules; a second electrode that is a counter electrode of the first electrode; a second substrate disposed on the second electrode and facing the first substrate with a gap therebetween; a sealing material disposed between the first substrate and the second substrate; A method for manufacturing a photoelectric conversion element having the first electrode, the second electrode, and a carrier transport material filling a region surrounded by the sealing material, the method comprising: a first substrate side forming step of forming the photoelectric conversion layer on a first substrate having the first electrode; a second substrate side forming step of forming a catalyst layer and a porous layer in contact with the catalyst layer on a second substrate having the second electrode; A method for manufacturing a photoelectric conversion element, characterized in that after the first substrate side formation process and the second substrate side formation process, the method includes a process of bonding the first substrate and the second substrate together via the sealing material, and arranging the photoelectric conversion layer and the porous layer opposite each other.

7. 7. The method for producing a photoelectric conversion element according to claim 6, The method for manufacturing a photoelectric conversion element, wherein the first substrate side forming step includes a dye printing step of laminating the dye molecules on the semiconductor fine particles by a printing method.

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