JP4824196B2 - Photoelectrode and dye-sensitized solar cell provided with the same - Google Patents

Description

【０１００】
表１に示した結果から明らかなように、実施例１〜実施例６の色素増感型太陽電池のエネルギー変換効率ηは、それぞれに対応する比較例１〜比較例８の色素増感型太陽電池のエネルギー変換効率ηよりも高い値を示すことが確認された。
【０１０１】
【発明の効果】
以上説明したように、本発明によれば、光電極を構成する半導体電極内において高い光閉じ込め効果を得ることが可能となるので、優れた入射光利用率を有する光電極を構成することができる。また、この光電極を用いることにより、優れたエネルギー変換効率を有する色素増感型太陽電池を構成することができる。
【図面の簡単な説明】
【図１】本発明の光電極の第一実施形態を示す模式断面図である。
【図２】図１に示した領域１００の部分の模式拡大断面図である。
【図３】図１に示した光電極を備えた色素増感型太陽電池を示す模式断面図である。
【図４】本発明の光電極の第二実施形態の半導体電極の内部構造を示す模式断面図である。
【図５】本発明の光電極の第三実施形態の半導体電極の内部構造を示す模式断面図である。
【図６】本発明の光電極の第四実施形態の半導体電極の内部構造を示す模式断面図である。
【図７】図１に示した光電極の他の実施形態を示す模式断面図である。
【符号の説明】
１…透明電極、２…半導体電極、３…透明導電膜、４…基板、１０，１１，１２，１３，１４…光電極，２０…色素増感型太陽電池、２１…最内部の層、２２…最外部の層、６３…内部層、１００…光電極１０の部分領域、ＣＥ…対極、Ｅ…電解質、Ｆ１，Ｆ２，Ｆ３，…受光面、Ｆ２２…半導体電極２の裏面、Ｌ１０…入射光、Ｌ１２…散乱光、Ｐ１…酸化物半導体粒子、Ｐ２…増感色素、Ｐ３…酸化物半導体粒子、Ｐ４…酸化物半導体粒子、Ｓ…スペーサー。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photoelectrode and a dye-sensitized solar cell including the photoelectrode.
[0002]
[Prior art]
In recent years, various developments of solar cells have been promoted with increasing interest in global warming and energy problems. Among such solar cells, dye-sensitized solar cells are expected to be put to practical use because they are inexpensive and can be manufactured by a relatively simple process.
[0003]
In conventional dye-sensitized solar cells, since the absorption coefficient of the sensitizing dye contained in the semiconductor electrode is small, even if light in the infrared to near-infrared wavelength region is incident on the semiconductor electrode, the semiconductor It penetrated without being sufficiently absorbed in the electrode, and did not contribute to the progress of the photoelectric conversion reaction.
[0004]
For this reason, various studies for improving the energy conversion efficiency of the battery by improving the absorption efficiency of incident light in the semiconductor electrode provided in the photoelectrode have been conducted for practical application of the dye-sensitized solar cell. ing. The energy conversion efficiency η (%) of the dye-sensitized solar cell is represented by the following formula (1). In the following formula (1), P₀Is the incident light intensity [mWcm^-2], V_ocIs the open circuit voltage [V], I_scIs the short-circuit current density [mAcm^-2], FF shows a fill factor.
η = 100 × (V_oc× I_sc× F.F.) / P₀... (1)
[0005]
As for the above examination, for example, in Japanese Patent Laid-Open No. 10-255863, a semiconductor electrode (light absorbing particle layer) having a small semiconductor particle having an average particle diameter of, for example, 80 nm or less as a constituent material is in contact with the electrolyte solution. On the surface, a layer (light reflecting particle layer) made of large semiconductor particles having an average particle diameter of 200 to 500 nm, for example, is provided to constitute a photoelectrode, and incident light incident on the semiconductor electrode is scattered. Thus, a dye-sensitized solar cell intended to improve the absorption efficiency has been proposed.
[0006]
Japanese Patent Laid-Open No. 2000-106222 discloses a semiconductor electrode in which semiconductor particles having a large particle size (average particle size: 10 to 300 nm) and semiconductor particles having a small particle size (average particle size: 10 nm or less) are mixed. Thus, a dye-sensitized solar cell intended to improve the absorption efficiency by scattering incident light incident on the semiconductor electrode has been proposed.
[0007]
[Problems to be solved by the invention]
However, the present inventors have disclosed a dye-sensitized solar cell provided with the photoelectrode described in JP-A-10-255863 and a dye-sensitized solar cell provided with the photoelectrode described in JP-A-2000-106222. In any of the batteries, sufficient incident light absorption efficiency is not obtained in the semiconductor electrode constituting the photoelectrode, and sufficient energy conversion efficiency as a battery cannot be obtained, which is still insufficient. I found.
[0008]
That is, in the dye-sensitized solar cells described in the above two publications, as a result of light scattering by the large semiconductor crystal particles, the optical path length passing through the semiconductor electrode is longer than when there is no large semiconductor particle. Although the utilization rate of the light increases, there is a problem that a part of the light passes through the semiconductor electrode because it uses the scattering phenomenon. In particular, as in the dye-sensitized solar cell described in the above two publications, the ratio of incident light that is transmitted without being absorbed by the semiconductor electrode when large semiconductor particles having a spherical shape are mixed in the semiconductor electrode. As a result, the light confinement effect in the semiconductor electrode is reduced, and the incident light absorption efficiency is reduced. In addition, when the number of large semiconductor crystal particles increases, the total surface area of the semiconductor surface to which the dye is adsorbed decreases, resulting in a decrease in light absorption rate.
[0009]
The present invention has been made in view of the above-mentioned problems of the prior art, and aims to provide a photoelectrode having excellent incident light absorption efficiency and a dye-sensitized solar cell having excellent energy conversion efficiency. To do.
[0010]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventors have configured the semiconductor electrode constituting the photoelectrode to be composed of a plurality of layers of at least three layers, and the oxide semiconductor particles contained in each layer, By increasing from the layer disposed closest to the transparent electrode to the layer disposed farthest from the transparent electrode, the light confinement effect of incident light in the semiconductor electrode can be greatly improved. The headline, the present invention has been reached.
[0011]
That is, the present invention is a photoelectrode having a semiconductor electrode having a light receiving surface and a transparent electrode disposed adjacent to the light receiving surface, wherein the semiconductor electrode is composed of a plurality of layers of three or more layers. Each of the plurality of layers includes oxide semiconductor particles as a semiconductor material, and the average particle diameter of the oxide semiconductor particles included in each layer is the closest to the transparent electrode. There is provided a photoelectrode characterized by increasing from an inner layer to an outermost layer disposed at a position farthest from the transparent electrode.
[0012]
With the semiconductor electrode having the above-described configuration, the amount of scattered light on the oxide semiconductor particles in each layer is applied to the surface (hereinafter referred to as the back surface) that is in contact with the electrolyte of the semiconductor electrode from the light receiving surface of the semiconductor electrode. It can be gradually increased along the thickness direction. For this reason, the photoelectrode of the present invention has a light scattering effect in the semiconductor electrode, as compared with any of the photoelectrode described in JP-A-10-255863 and the photoelectrode described in JP-A-2000-106222. Efficiency can be improved more reliably. Therefore, the photoelectrode of the present invention can obtain excellent incident light absorption efficiency.
[0013]
Here, in the present invention, the state that “the average particle diameter of the oxide semiconductor particles contained in each layer increases from the innermost layer to the outermost layer” is the state of the outermost layer located at one end. The average particle diameter of the oxide semiconductor particles is finally larger than the average particle diameter of the oxide semiconductor particles of the innermost layer located at the other end, and when a plurality of layers are viewed as a whole, the oxide of each layer It shows a state in which the average particle diameter of the semiconductor particles is roughly increased from the innermost layer to the outermost layer.
[0014]
For example, the average particle diameter of the oxide semiconductor particles may be monotonously increasing from the innermost layer to the outermost layer. Further, for example, among the layers arranged between the innermost layer and the outermost layer, even if the average particle size of the oxide semiconductor particles of some adjacent layers takes the same value, Good. Furthermore, when the average particle size of the oxide semiconductor particles of some adjacent layers among the layers arranged between the innermost layer and the outermost layer is compared, the innermost layer side There may be a case where the average particle diameter of the positioned layer is larger than the average particle diameter of the layer positioned on the outermost layer side. However, from the viewpoint of sufficiently ensuring the absorption efficiency of incident light of the semiconductor electrode, the average particle diameter of the oxide semiconductor particles monotonously increases from the innermost layer to the outermost layer, or the innermost Of the layers arranged between the outermost layer and the outermost layer, it is preferable that the average particle diameters of the oxide semiconductor particles of some adjacent layers have the same value.
[0015]
In the photoelectrode of the present invention, the average particle diameter of the oxide semiconductor particles in the outermost layer is 50 to 500 nm, and the average particle diameter of the oxide semiconductor particles in the outermost layer and the innermost layer The difference from the average particle diameter of the oxide semiconductor particles in is preferably 10 to 400 nm. Thereby, the light scattering efficiency in a semiconductor electrode can be improved more precisely.
[0016]
Here, if the average particle size of the oxide semiconductor particles in the outermost layer is less than 50 nm, the amount and ratio of the large-diameter particles that scatter the light that can be absorbed by the sensitizing dye decrease, and the light scattering efficiency is insufficient. There is a risk of becoming. On the other hand, if the average particle size of the oxide semiconductor particles in the outermost layer exceeds 500 nm, the amount of sensitizing dye in the electrode may be reduced, and the incident light absorption efficiency may be reduced. Further, if the difference between the average particle size of the oxide semiconductor particles in the outermost layer and the average particle size of the oxide semiconductor particles in the innermost layer is less than 10 nm, the light confinement effect may be insufficient. . On the other hand, if this difference exceeds 400 nm, the average particle diameter of the oxide semiconductor particles in the outermost layer may increase, and the amount of sensitizing dye in the electrode may decrease.
[0017]
From the same viewpoint as described above, the average particle size of the oxide semiconductor particles in the outermost layer is more preferably 70 to 400 nm, and still more preferably 80 to 300 nm. The difference between the average particle diameter of the oxide semiconductor particles in the outermost layer and the average particle diameter of the oxide semiconductor particles in the innermost layer is more preferably 20 to 300 nm, and preferably 25 to 250 nm. Further preferred.
[0018]
Further, in the photoelectrode of the present invention, the oxide semiconductor particles contained in each layer of the semiconductor electrode are composed of small particles having an average particle diameter of 5 to 100 nm and large particles having an average particle diameter exceeding 100 nm. The mixing ratio of the large-diameter particles to the total amount of the large-diameter particles may increase from the innermost layer to the outermost layer.
[0019]
As described above, the oxide semiconductor particles to be contained in each layer of the semiconductor electrode are used by mixing the above-mentioned small-diameter particles and large-diameter particles, and further including the blending conditions as described above. As described above, the average particle size of the oxide semiconductor particles can be increased from the innermost layer to the outermost layer.
[0020]
Here, in this case, when the average particle diameter of the small-diameter particles is less than 5 nm, the pore diameter in the semiconductor electrode layer is reduced, and the time for adsorbing the sensitizing dye is increased or the sensitizing dye is dissolved in the electrolyte. Diffusion may be difficult. On the other hand, when the average particle diameter of the small diameter particles exceeds 100 nm, the amount of the sensitizing dye in the electrode may be reduced. Further, if the average particle size of the large particles is 100 nm or less, the light scattering effect is small and the light confinement effect may be insufficient. From the same viewpoint as described above, the average particle size of the small particles is more preferably 10 to 80 nm, and further preferably 15 to 70 nm. The average particle size of the large particles is more preferably greater than 100 nm and 600 nm or less, and even more preferably 120 to 450 nm.
[0021]
Further, in this case, from the viewpoint of satisfying the same conditions as the conditions for the average particle diameter of the oxide semiconductor particles contained in each layer described above, the large amount relative to the total amount of the small diameter particles and the large diameter particles in the outermost layer. The blending ratio of the diameter particles is preferably 5 to 100% by mass, and more preferably 20 to 100% by mass.
[0022]
In the photoelectrode of the present invention, the oxide semiconductor particles contained in each of a plurality of layers excluding the innermost layer of the semiconductor electrode are small particles having an average particle size of 5 to 100 nm and an average particle size of 100 nm. The oxide semiconductor particles contained in the innermost layer are small-diameter particles, and the mixing ratio of the large-diameter particles to the total amount of the small-diameter particles and the large-diameter particles is the highest among the plurality of layers. It may increase from the layer disposed closest to the inner layer to the outermost layer.
[0023]
As described above, as the oxide semiconductor particles to be contained in each layer of the semiconductor electrode, the above-mentioned small-diameter particles are used as the oxide semiconductor particles contained in the innermost layer, and each of a plurality of layers excluding the innermost layer is used. As the oxide semiconductor particles contained, the above-mentioned small-diameter particles and large-diameter particles are mixed and used, and the average particle size of the oxide semiconductor particles contained in each layer can be obtained by setting the blending conditions as described above. The diameter can be increased from the innermost layer to the outermost layer as described above.
[0024]
Also in this case, the average particle diameter of the small-diameter particles is more preferably 10 to 80 nm, and further preferably 15 to 70 nm. The average particle size of the large particles is more preferably greater than 100 nm and 600 nm or less, and even more preferably 120 to 450 nm. Furthermore, the blending ratio of the large diameter particles to the total amount of the small diameter particles and the large diameter particles in the outermost layer is preferably 5 to 100% by mass, and more preferably 20 to 100% by mass.
[0025]
Moreover, the photoelectrode of the present invention may contain at least two kinds of oxide semiconductor particles having different average particle diameters in at least one of the plurality of layers of the semiconductor electrode. Also in this case, the average particle diameter of the oxide semiconductor particles contained in each layer can be increased from the innermost layer to the outermost layer as described above. For example, among the plurality of layers of the semiconductor electrode, only one layer made of at least two kinds of oxide semiconductor particles having different average particle diameters may be used, and each of the other layers may be made of one kind of oxide semiconductor particles. . In this case, as the at least two kinds of oxide semiconductor particles having different average particle diameters, a small particle having an average particle diameter of 5 to 100 nm and a large particle having an average particle diameter exceeding 100 nm may be used.
[0026]
The present invention also includes a photoelectrode having a semiconductor electrode having a light receiving surface, a transparent electrode disposed adjacent to the light receiving surface of the semiconductor electrode, and a counter electrode. Provided is a dye-sensitized solar cell disposed opposite to an electrolyte, wherein the photoelectrode is the above-described photoelectrode of the present invention. Thus, the dye-sensitized solar cell which has the outstanding energy conversion efficiency can be comprised by using the photoelectrode of this invention mentioned above.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the photoelectrode and the dye-sensitized solar cell of the present invention will be described in detail with reference to the drawings. In the following description, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.
[0028]
[First embodiment]
FIG. 1 is a schematic cross-sectional view showing a first embodiment of the photoelectrode of the present invention. FIG. 2 is a schematic enlarged sectional view of a portion of the region 100 shown in FIG. 3 is a schematic cross-sectional view showing a dye-sensitized solar cell including the photoelectrode shown in FIG.
[0029]
The photoelectrode 10 shown in FIG. 1 is mainly composed of a semiconductor electrode 2 having a light receiving surface F2 and a transparent electrode 1 disposed adjacent to the light receiving surface F2 of the semiconductor electrode 2. Further, the dye-sensitized solar cell 20 shown in FIG. 3 mainly fills a gap formed between the photoelectrode 10 and the counter electrode CE by the photoelectrode 10, the counter electrode CE, and the spacer S shown in FIG. The electrolyte E is made. And the semiconductor electrode 2 is contacting the electrolyte E in the back surface F22 on the opposite side to the light-receiving surface F2.
[0030]
The dye-sensitized solar cell 20 generates electrons in the semiconductor electrode 2 by the light L10 that is transmitted through the transparent electrode 1 and irradiated onto the semiconductor electrode 2. The electrons generated in the semiconductor electrode 2 are collected by the transparent electrode 1 and taken out to the outside.
[0031]
The structure of the transparent electrode 1 is not specifically limited, The transparent electrode mounted in a normal dye-sensitized solar cell can be used. For example, the transparent electrode 1 in FIGS. 1 and 3 has a configuration in which a so-called transparent conductive film 3 for transmitting light is coated on the semiconductor electrode 2 side of a transparent substrate 4 such as a glass substrate. As the transparent conductive film 3, a transparent electrode used for a liquid crystal panel or the like may be used. For example, fluorine-doped SnO₂Examples include coated glass, ITO coated glass, ZnO: Al coated glass, and the like. Further, a metal electrode having a structure capable of transmitting light, such as a mesh shape or a stripe shape, may be provided on the substrate 4 such as a glass substrate.
[0032]
As the transparent substrate 4, a transparent substrate used for a liquid crystal panel or the like may be used. Specific examples of the transparent substrate material include transparent glass substrates, materials that prevent the reflection of light by appropriately roughening the surface of the glass substrate, and materials that transmit light, such as a ground glass-like translucent glass substrate. Note that the material may not be glass as long as it transmits light, and may be a transparent plastic plate, a transparent plastic film, an inorganic transparent crystal, or the like.
[0033]
As shown in FIGS. 1 and 2, the semiconductor electrode 2 is composed of three layers containing oxide semiconductor particles as constituent materials. That is, the semiconductor electrode 2 includes an innermost layer 21 disposed at a position closest to the transparent electrode 1, an outermost layer 22 disposed at a position farthest from the transparent electrode 1, and an innermost layer 21. And an inner layer 23 disposed between the outermost layer 22 and the outermost layer 22. When comparing the average particle size of the oxide semiconductor particles contained in each of the three layers, the average particle size of the oxide semiconductor particles for each layer increases from the innermost layer 21 to the outermost layer 22. Yes. Furthermore, the average particle diameter of the oxide semiconductor particles in the outermost layer is preferably adjusted to be 70 to 400 nm, and the average particle diameter of the oxide semiconductor particles in the outermost layer and the oxidation in the innermost layer are adjusted. The difference from the average particle size of the physical semiconductor particles is preferably adjusted to be 20 to 300 nm. In this photoelectrode 10, by providing the semiconductor electrode 2 having the above structure, the absorption efficiency of incident light in the semiconductor electrode 2 is improved.
[0034]
That is, as shown in FIG. 2, a part of the light L10 incident from the light receiving surface F1 of the transparent electrode 1 and transmitted through the innermost layer 21 is an oxide having a larger average particle diameter contained in the inner layer 23. The light is efficiently reflected on the semiconductor particles P3, becomes scattered light L12, and is efficiently returned to the innermost layer 21 again. Further, a part of light (not shown) transmitted through the inner layer 23 is also efficiently reflected on the oxide semiconductor particles P3 contained in the outermost layer 22 to be scattered light (not shown). Then, it is efficiently returned to the innermost layer 21 again. Due to the high light confinement effect in each layer of the semiconductor electrode 2, excellent incident light absorption efficiency can be obtained in the semiconductor electrode 2.
[0035]
As shown in FIG. 2, the innermost layer 21 of the semiconductor electrode 2 is mainly composed of oxide semiconductor particles (small-diameter particles) P1 and a sensitizing dye P2 adsorbed on the surface of the oxide semiconductor particles P1. ing. The inner layer 23 and the outermost layer 22 are mainly composed of oxide semiconductor particles P1, oxide semiconductor particles (large diameter particles) P3 having a larger particle diameter than the oxide semiconductor particles P1, and these oxide semiconductors. It is comprised from the sensitizing dye P2 adsorb | sucked by the surface of particle | grains P1 and oxide semiconductor particle P3.
[0036]
Here, the average particle diameter of the oxide semiconductor particles (small-diameter particles) P1 is preferably adjusted to be 5 to 100 nm. The average particle size of the oxide semiconductor particles (large particle) P3 is preferably adjusted to be larger than 100 nm. And the compounding ratio of the oxide semiconductor particle P3 with respect to the total amount of the oxide semiconductor particle P1 and the oxide semiconductor particle P3 in the outermost layer 22 is the oxide semiconductor particle P1 and the oxide semiconductor particle P3 in the inner layer 23. It is adjusted to be larger than the blending ratio of the oxide semiconductor particles P3 with respect to the total amount. As a result, the average particle diameter of the oxide semiconductor particles for each layer increases from the innermost layer 21 to the outermost layer 22. In the case of this photoelectrode 10, the innermost layer 21 does not substantially contain the oxide semiconductor particles P3.
[0037]
The oxide semiconductor particles P1 and the oxide semiconductor particles P3 are not particularly limited, and known oxide semiconductors and the like can be used. As an oxide semiconductor, for example, TiO₂, ZnO, SnO₂, Nb₂O_Five, In₂O_Three, WO_Three, ZrO₂, La₂O_Three, Ta₂O_Five, SrTiO_Three, BaTiO_ThreeEtc. can be used.
[0038]
Moreover, the sensitizing dye P2 contained in the first semiconductor layer 5 and the second semiconductor layer 6 of the semiconductor electrode 2 is not particularly limited, and the dye has absorption in the visible light region and / or the infrared light region. If it is. As this sensitizing dye P2, a metal complex, an organic dye, or the like can be used. Metal complexes include metal phthalocyanines such as copper phthalocyanine and titanyl phthalocyanine, chlorophyll or derivatives thereof, hemin, ruthenium, osmium, iron and zinc complexes (eg cis-dicyanate-bis (2,2′-bipyridyl-4,4′- Dicarboxylate) ruthenium (II)) and the like. As the organic dye, metal-free phthalocyanine, cyanine dye, methocyanine dye, xanthene dye, triphenylmethane dye, and the like can be used.
[0039]
Moreover, it is preferable that the thickness of the semiconductor electrode 2 is 3-50 micrometers, It is more preferable that it is 5-30 micrometers, It is still more preferable that it is 6-18 micrometers. When the thickness of the semiconductor electrode is less than 3 μm, the amount of dye adsorbed decreases, and the tendency that light cannot be effectively absorbed increases. On the other hand, when the thickness of the semiconductor electrode exceeds 50 μm, the electrical resistance increases and the loss amount of carriers injected into the semiconductor increases, and the ion diffusion resistance increases, and photoexcitation causes electron injection into the semiconductor. I for later dyes^-I by electron injection from_Three ^-Of the battery to the counter electrode is hindered, and the tendency of the output characteristics of the battery to decrease increases.
[0040]
Further, the counter electrode CE is not particularly limited, and for example, the same counter electrode as that normally used for a silicon solar cell, a liquid crystal panel, or the like may be used. For example, it may have the same structure as the transparent electrode 1 described above, a metal thin film electrode such as Pt is formed on the transparent conductive film 3 similar to the transparent electrode 1, and the metal thin film electrode is placed on the electrolyte E side. It may be arranged to face. Alternatively, a small amount of platinum may be attached to the transparent conductive film 3 of the transparent electrode 1, or a metal thin film such as platinum, a conductive film such as carbon, or the like may be used.
[0041]
Furthermore, the composition of the electrolyte E is not particularly limited as long as it contains a redox species for reducing the dye after photoexcitation and electron injection into the semiconductor.^-/ I_Three ^-An iodine redox solution containing a redox species such as the above is preferably used. Specifically, I^-/ I_Three ^-As the system electrolyte, an ammonium salt of iodine or a mixture of lithium iodide and iodine can be used. Other, Br^-/ Br_Three ^-A quinone / hydroquinone redox electrolyte dissolved in an electrochemically inert solvent (and mixed solvent thereof) such as acetonitrile, propylene carbonate, and ethylene carbonate can also be used.
[0042]
The constituent material of the spacer S is not particularly limited, and for example, silica beads or the like can be used.
[0043]
Next, an example of a manufacturing method of the photoelectrode 10 shown in FIG. 1 and the dye-sensitized solar cell 20 shown in FIG. 3 will be described.
[0044]
First, when the transparent electrode 1 is manufactured, the fluorine-doped SnO described above on the substrate 4 such as a glass substrate.₂The transparent conductive film 3 can be formed using a known method such as spray coating.
[0045]
Next, as a method of forming each layer of the semiconductor electrode 2 on the transparent conductive film 3 of the transparent electrode 1, for example, there are the following methods. That is, first, a dispersion for forming the innermost layer 21 in which semiconductor particles P1 such as titanium oxide are dispersed is prepared. The solvent of the dispersion is not particularly limited as long as it can disperse the oxide semiconductor particles P1, such as water, an organic solvent, or a mixed solvent of both. Moreover, you may add surfactant and a viscosity modifier to a dispersion liquid as needed. Next, the dispersion is applied onto the transparent conductive film 3 of the transparent electrode 1 and then dried. As a coating method at this time, a bar coater method, a printing method, or the like can be used. Then, after drying, the innermost layer 21 (porous semiconductor film) of the semiconductor electrode 2 is formed by heating and baking in air, inert gas or nitrogen. The firing temperature at this time is preferably 300 to 800 ° C. If the firing temperature is lower than 300 ° C., the adhesion between the oxide semiconductor particles P1 and the adhesion to the substrate may be weakened, and sufficient strength may not be obtained. If the firing temperature exceeds 800 ° C., the sticking between the oxide semiconductor particles P1 proceeds, and the surface area of the semiconductor electrode 2 (porous semiconductor film) may be reduced.
[0046]
Next, when the inner layer 23 is formed on the innermost layer 21, for example, a predetermined amount of the oxide semiconductor particles P3 is further added to the dispersion for forming the innermost layer 21. The inner layer 23 can be formed in the same manner as the method for forming the innermost layer 21 described above except that a dispersion having the above composition is prepared. Further, when the outermost layer 22 is formed on the inner layer 23, for example, a predetermined amount of the oxide semiconductor particles P3 is further added to the dispersion for forming the innermost layer 21. The outermost layer 22 can be formed on the inner layer 23 in the same manner as the method for forming the innermost layer 21 described above, except that a dispersion having a composition is prepared.
[0047]
Next, the sensitizing dye P2 is contained in the semiconductor electrode 2 by a known method such as an adhesion method. The sensitizing dye P2 is contained by adhering to the semiconductor electrode 2 (chemical adsorption, physical adsorption or deposition). As this adhesion method, for example, a method of immersing the semiconductor electrode 2 in a solution containing a dye can be used. At this time, adsorption and deposition of the sensitizing dye can be promoted by heating and refluxing the solution. At this time, a metal such as silver or a metal oxide such as alumina may be contained in the semiconductor electrode 2 in addition to the pigment, if necessary.
[0048]
The surface oxidation treatment for removing impurities that inhibit the photoelectric conversion reaction contained in the semiconductor electrode 2 may be appropriately performed by a known method every time each layer is formed or when all the layers are formed. .
[0049]
Other methods for forming the semiconductor electrode 2 on the transparent conductive film 3 of the transparent electrode 1 include the following methods. That is, on the transparent conductive film 3 of the transparent electrode 1 TiO₂A method of vapor-depositing a semiconductor such as a film may be used. As a method for depositing a semiconductor on the transparent conductive film 3 in a film shape, a known method can be used. For example, a physical vapor deposition method such as electron beam vapor deposition, resistance heating vapor deposition, sputter vapor deposition, or cluster ion beam vapor deposition may be used. Metal or the like is evaporated in a reactive gas such as oxygen, and the reaction product is converted into the transparent conductive film 3. A reactive vapor deposition method may be used. Furthermore, chemical vapor deposition such as CVD can be used by controlling the flow of the reaction gas.
[0050]
After producing the photoelectrode 10 in this manner, a counter electrode CE is produced by a known method, and this, the photoelectrode 10 and the spacer S are assembled as shown in FIG. The dye-sensitized solar cell 20 is completed.
[0051]
[Second Embodiment]
Hereinafter, a second embodiment of the photoelectrode of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected about the element same as the element demonstrated regarding 1st embodiment mentioned above, and the overlapping description is abbreviate | omitted. FIG. 4 is a schematic cross-sectional view showing the internal structure of the semiconductor electrode of the second embodiment of the photoelectrode of the present invention.
[0052]
In the photoelectrode 11 (not shown) of the present embodiment, as shown in FIG. 4, the innermost layer 21 of the semiconductor electrode 2 also contains oxide semiconductor particles (large-diameter particles) P3. The blending ratio of the oxide semiconductor particles (large diameter particles) P3 to the total amount of the oxide semiconductor particles P1 (small diameter particles) and the oxide semiconductor particles (large diameter particles) P3 is changed from the innermost layer 21 to the outermost layer. Except for the increase to 22, it has the same configuration as the photoelectrode 10 shown in FIG. 1. Thereby, the average particle diameter of the oxide semiconductor particles for each layer increases from the innermost layer 21 to the outermost layer 22. In this photoelectrode 11, by providing the semiconductor electrode 2 having the above structure, the absorption efficiency of incident light in the semiconductor electrode 2 is improved.
[0053]
The dye-sensitized solar cell (not shown) provided with the photoelectrode 11 has the same configuration as the dye-sensitized solar cell 10 shown in FIG. 1 except for the photoelectrode 11. Moreover, the manufacturing method of the dye-sensitized solar cell provided with the photoelectrode 11 and the photoelectrode 11 is not specifically limited, For example, it manufactures with the method similar to the photoelectrode 10 and the dye-sensitized solar cell 20 mentioned above. can do.
[0054]
[Third embodiment]
Hereinafter, a third embodiment of the photoelectrode of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected about the element same as the element demonstrated regarding 1st embodiment mentioned above, and the overlapping description is abbreviate | omitted. FIG. 5 is a schematic cross-sectional view showing the internal structure of the semiconductor electrode of the third embodiment of the photoelectrode of the present invention.
[0055]
As shown in FIG. 5, the photoelectrode 12 (not shown) of the present embodiment, except that the semiconductor material constituting the outermost layer 22 of the semiconductor electrode 2 is only one kind of oxide semiconductor particles P3. It has the same configuration as the photoelectrode 10 shown in FIG. That is, the semiconductor electrode 2 shown in FIG. 5 includes two kinds of oxide semiconductor particles (oxide semiconductor particles P1 (small diameter particles) and oxide semiconductor particles (large diameter particles) P3) in which only the inner layer 22 has different average particle diameters. The other layers are formed of one kind of oxide semiconductor particles. Also in this case, the average particle diameter of the oxide semiconductor particles for each layer increases from the innermost layer 21 to the outermost layer 22. In this photoelectrode 12, by providing the semiconductor electrode 2 having the above structure, the absorption efficiency of incident light in the semiconductor electrode 2 is improved.
[0056]
A dye-sensitized solar cell (not shown) provided with the photoelectrode 12 has the same configuration as the dye-sensitized solar cell 10 shown in FIG. 1 except for the photoelectrode 12. Moreover, the manufacturing method of the dye-sensitized solar cell provided with the photoelectrode 12 and the photoelectrode 12 is not specifically limited, For example, it manufactures by the method similar to the photoelectrode 10 and the dye-sensitized solar cell 20 mentioned above. can do.
[0057]
[Fourth embodiment]
Hereinafter, a third embodiment of the photoelectrode of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected about the element same as the element demonstrated regarding 1st embodiment mentioned above, and the overlapping description is abbreviate | omitted. FIG. 6 is a schematic cross-sectional view showing the internal structure of the semiconductor electrode of the third embodiment of the photoelectrode of the present invention.
[0058]
As shown in FIG. 6, the photoelectrode 13 (not shown) of the present embodiment has only one kind of oxide semiconductor particles P3 as a semiconductor material constituting the inner layer 23 of the semiconductor electrode 2, and the outermost layer. 1 has the same configuration as that of the photoelectrode 10 shown in FIG. 1 except that the semiconductor material constituting 22 is only one kind of oxide semiconductor particles P4. In this case, the average particle diameter of the oxide semiconductor particles P4 constituting the outermost layer 22 is adjusted to be larger than the average particle diameter of the oxide semiconductor particles P3. Also in this case, the average particle diameter of the oxide semiconductor particles for each layer increases from the innermost layer 21 to the outermost layer 22. In this photoelectrode 13, by providing the semiconductor electrode 2 having the above structure, the absorption efficiency of incident light in the semiconductor electrode 2 is improved.
[0059]
A dye-sensitized solar cell (not shown) provided with the photoelectrode 13 has the same configuration as the dye-sensitized solar cell 10 shown in FIG. 1 except for the photoelectrode 13. Moreover, the manufacturing method of the dye-sensitized solar cell provided with the photoelectrode 13 and the photoelectrode 13 is not specifically limited, For example, it manufactures with the method similar to the photoelectrode 10 and the dye-sensitized solar cell 20 mentioned above. can do.
[0060]
The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.
[0061]
For example, in the above-described embodiment, the photoelectrode including the semiconductor electrode having a three-layer structure and the dye-sensitized solar cell including the semiconductor electrode have been described. However, the photoelectrode and the dye-sensitized solar cell of the present invention are It is not limited to this. For example, the photoelectrode of the present invention may have a configuration including the semiconductor electrode 2 composed of four or more layers, like the photoelectrode 14 shown in FIG. For example, the semiconductor electrode 2 of the photoelectrode 14 shown in FIG. 7 includes an innermost layer 21 and an outermost layer 22, an inner layer 23 disposed between the innermost layer 21 and the outermost layer 22, and 24. In this case, when the average particle diameters of the oxide semiconductor particles included in the four layers of the semiconductor electrode 2 are compared, the average particle diameter of the oxide semiconductor particles for each layer is changed from the innermost layer 21 to the outermost layer. It is adjusted so as to increase over the layer 22.
[0062]
【Example】
Hereinafter, the photoelectrode and the dye-sensitized solar cell of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.
[0063]
Example 1
A photoelectrode having the same configuration as that of the photoelectrode 12 shown in FIG. 5 is prepared by the following procedure, and the same as the dye-sensitized solar cell 20 shown in FIG. 3 except that this photoelectrode is used. A 5 × 20 mm scale dye-sensitized solar cell having the structure was prepared.
[0064]
First, TiO₂Particles (anatase, manufactured by Nippon Aerosil Co., Ltd., trade name: “P25”, average particle size: 25 nm, hereinafter referred to as “P25”), acetylacetone, ion-exchanged water, surfactant (manufactured by Tokyo Chemical Industry Co., Ltd., trade name: “Triton-X ”) Was added and kneaded to prepare a slurry for forming the innermost layer 21 (P25 content; 15 mass%, hereinafter referred to as slurry 1).
[0065]
Next, P25 and commercially available large diameter TiO₂The same preparation as slurry 1 described above except that particles (anatase, average particle size; 180 nm, hereinafter referred to as P180) were used and the mass ratio of P25 and P180 was P25: P180 = 1: 1. By the procedure, a slurry for forming the inner layer 23 (P25 content: 7.5 mass%, P180 content; 7.5 mass%, hereinafter referred to as slurry 2) was prepared.
[0066]
Next, a slurry for forming the inner layer 23 (content of P180; 15 mass%, hereinafter referred to as slurry 3) was prepared by the same preparation procedure as that of the slurry 1 except that only P180 was used.
[0067]
On the other hand, SnO doped with fluorine on the glass substrate 4 (transparent conductive glass)₂A transparent electrode 1 (thickness: 1.1 mm) on which a conductive film 3 (film thickness: 700 nm) was formed was prepared. And this SnO₂The above-mentioned slurry 1 was applied onto the conductive film 3 using a bar coder, and then dried. Then, it baked for 30 minutes on condition of 450 degreeC in air | atmosphere.
[0068]
Furthermore, by repeating this coating and firing using slurry 2 and slurry 3, SnO₂A semiconductor electrode having the same configuration as the semiconductor electrode 2 shown in FIG. 5 on the conductive film (light-receiving surface area; 1.0 cm)²Layer thickness; 15 μm, layer thickness of innermost layer 21; 5 μm, layer thickness of inner layer 23; 5 μm, layer thickness of outermost layer 22; 5 μm), and light containing no sensitizing dye An electrode was produced.
[0069]
Then, the pigment | dye was made to adsorb | suck to the back surface of a semiconductor electrode as follows. First, a ruthenium complex [cis-Di (thiocyanato) -N, N'-bis (2,2'-bipyridyl-4,4'dicarboxylic acid) -ruthenium (II)]] is used as a sensitizing dye, and an ethanol solution thereof is used. (Sensitizing dye concentration; 3 × 10^-Fourmol / L) was prepared. Next, the semiconductor electrode was immersed in this solution and allowed to stand under a temperature condition of 80 ° C. for 20 hours. Thereby, a sensitizing dye is added to the inside of the semiconductor electrode 2 by about 1.0 × 10.^-7mol / cm²Adsorbed. Next, in order to improve the open circuit voltage Voc, the semiconductor electrode after the adsorption of the ruthenium complex was immersed in an acetonitrile solution of 4-tert-butylpyridine for 15 minutes and then dried in a nitrogen stream maintained at 25 ° C. 12 was completed.
[0070]
Next, as a counter electrode having the same shape and size as the above-described photoelectrode, a transparent conductive glass electrode (thickness of Pt thin film; 3 nm) on which Pt was deposited by an electron beam deposition method was produced. In addition, an iodine redox solution containing iodine, lithium iodide, and imidazolium salt was prepared as the electrolyte E. Further, a spacer S (trade name: “HIMILAN”) manufactured by Mitsui DuPont Polychemical Co., Ltd. having a shape corresponding to the size of the semiconductor electrode is prepared. As shown in FIG. 3, the photoelectrode 12, the counter electrode CE, and the spacer S are prepared. The dye was sensitized and filled with the above electrolyte to complete a dye-sensitized solar cell.
[0071]
(Example 2)
Except that the semiconductor electrode was manufactured as follows, the same configuration as that of the photoelectrode 10 shown in FIG. 2 and the dye-sensitized solar cell 20 shown in FIG. A photoelectrode and a dye-sensitized solar cell were prepared.
[0072]
First, using P25 and P180, and the mass ratio of P25 and P180 was set to P25: P180 = 7: 3, the preparation procedure for the inner layer 23 was performed in the same manner as the slurry 1 described above. A slurry (content of P25; 10.5% by mass, content of P180; 4.5% by mass, hereinafter referred to as slurry 4) was prepared.
[0073]
Then, the innermost layer 21 was formed using the slurry 1 described above, the inner layer 23 was formed using the slurry 4, and the outermost layer 22 was formed using the slurry 2. Except that, SnO was the same as Example 1.₂A semiconductor electrode having the same structure as the semiconductor electrode 2 shown in FIG. 1 on the conductive film (light receiving surface area; 1 cm)²Layer thickness; 15 μm, layer thickness of innermost layer 21; 5 μm, layer thickness of inner layer 23; 5 μm, layer thickness of outermost layer 22; 5 μm), and light containing no sensitizing dye An electrode was produced.
[0074]
(Example 3)
Except that the semiconductor electrode was manufactured as follows, the same configuration as that of the photoelectrode 10 shown in FIG. 1 and the dye-sensitized solar cell 20 shown in FIG. A photoelectrode and a dye-sensitized solar cell were prepared.
[0075]
In the autoclave, a chemical species containing Ti (titanium alkoxide), ion-exchanged water, a pH adjuster (nitric acid, ammonia, etc.) is added, and under a predetermined reaction condition, a hydrolysis reaction of the chemical species containing Ti proceeds. The resulting TiO₂By proceeding crystallization of the particles, TiO with an average particle size of 27 nm₂A colloid solution (hereinafter referred to as colloid solution 1) containing particles (anatase, hereinafter referred to as P27) was prepared. Next, TiO having an average particle diameter of 56 nm is obtained by the same procedure as that of the colloid solution 1 except that the reaction conditions in the autoclave are changed.₂Colloidal solution (hereinafter referred to as colloidal solution 2) containing particles (anatase, hereinafter referred to as P56), TiO having an average particle size of 112 nm₂Colloidal solution (hereinafter referred to as colloid solution 3) containing particles (anatase, hereinafter referred to as P112), TiO having an average particle diameter of 198 nm₂A colloidal solution (hereinafter referred to as colloid solution 4) containing particles (anatase, hereinafter referred to as P198) was prepared. TiO contained in these colloidal solutions 1 to 4₂The average particle diameter of the particles was determined by analyzing dynamic light scattering of laser light using a light scattering photometer (manufactured by Otsuka Electronics Co., Ltd.).
[0076]
Next, TiO 2 is obtained by subjecting each of the colloid solutions 1 to 4 to solvent dilution and solvent removal.₂The following paste was prepared by adjusting the concentration of the particles and adding a cellulose-based viscosity modifier.
[0077]
That is, the paste containing only P27 using the colloid solution 1 (P27 content; 12 mass%, hereinafter referred to as paste 1), the colloid solution 1 and the colloid solution 4 are used, and the mass ratio of P27 and P198 is set. P27: P198 = 7: 3 paste (hereinafter referred to as paste 2), colloid solution 1 and colloid solution 4 were used, and the mass ratio of P27 and P198 was set to P27: P198 = 1: 1 (hereinafter referred to as “paste”). Paste 2) was prepared.
[0078]
Then, paste 1 was used for forming the innermost layer 21, paste 2 was used for forming the inner layer 23, and paste 3 was used for forming the outermost layer 22. That is, a semiconductor electrode having the same configuration as the semiconductor electrode 2 and the semiconductor electrode 2 shown in FIG. 1 is formed on the transparent electrode 1 by the same procedure as in Example 1 except that the pastes 1 to 3 are screen printed. 1cm²12 μm, the layer thickness of the innermost layer 21; 4 μm, the layer thickness of the inner layer 23; 4 μm, the layer thickness of the outermost layer 22; 4 μm).
[0079]
Example 4
Except that the semiconductor electrode was manufactured as follows, the same configuration as that of the photoelectrode 10 shown in FIG. 1 and the dye-sensitized solar cell 20 shown in FIG. A photoelectrode and a dye-sensitized solar cell were prepared.
[0080]
That is, the paste 2 used in Example 3 was used for forming the innermost layer 21. The paste 3 used in Example 3 was used for forming the inner layer 23. Further, a paste containing only P198 (a content of P198; 12 mass%, hereinafter referred to as paste 4) was prepared using the colloid solution 4 and used for forming the outermost layer 22.
[0081]
A semiconductor electrode having the same structure as the semiconductor electrode 2 shown in FIG. 1 is formed on the transparent electrode 1 (area of the light receiving surface; 1.0 cm) by the same procedure as in Example 1 except that each paste is screen printed.²12 μm, the layer thickness of the innermost layer 21; 4 μm, the layer thickness of the inner layer 23; 4 μm, the layer thickness of the outermost layer 22; 4 μm).
[0082]
(Example 5)
Except that the semiconductor electrode was manufactured as follows, the same configuration as that of the photoelectrode 10 shown in FIG. 1 and the dye-sensitized solar cell 20 shown in FIG. A photoelectrode and a dye-sensitized solar cell were prepared.
[0083]
That is, using the colloidal solution 1 and the colloidal solution 3 prepared in Example 3, the mass ratio of P27 and P112 was P27: P112 = 7: 3 (P27 content; 8.4 mass%, P112 Content of 3.6% by mass, hereinafter referred to as paste 5), and this was used to form the innermost layer 21.
[0084]
Moreover, the paste (P27 content; 6 mass%, P112 content) in which the mass ratio of P27 and P112 was set to P27: P112 = 1: 1 using the colloidal solution 1 and the colloidal solution 3 prepared in Example 3 Amount: 6 mass%, hereinafter referred to as paste 6), and this was used to form the inner layer 23. Further, the outermost layer 22 was formed using the paste 4 prepared in Example 4.
[0085]
A semiconductor electrode having the same structure as the semiconductor electrode 2 shown in FIG. 1 is formed on the transparent electrode 1 (area of the light receiving surface; 1.0 cm) by the same procedure as in Example 1 except that each paste is screen printed.²12 μm, the layer thickness of the innermost layer 21; 4 μm, the layer thickness of the inner layer 23; 4 μm, the layer thickness of the outermost layer 22; 4 μm).
[0086]
(Example 6)
The innermost layer 21 was formed using the paste 1 made of only P27 prepared in Example 3. Also, a paste containing only P56 (P56 content; 12 mass%, hereinafter referred to as paste 7) was prepared using the colloidal solution 2 prepared in Example 3, and this was used to form the inner layer 23. . Further, the paste 4 consisting only of P198 prepared in Example 4 was used to form the outermost layer 22.
[0087]
A semiconductor electrode having the same configuration as the semiconductor electrode 2 shown in FIG. 1 on the transparent electrode 1 (light-receiving surface area; 0cm²12 μm, the thickness of the innermost layer 21; 4 μm, the layer thickness of the inner layer 23; 4 μm, the layer thickness of the outermost layer 22; 4 μm).
[0088]
(Comparative Example 1)
A semiconductor electrode composed of only one layer using only the slurry 1 used in Example 1 (light receiving surface area; 1.0 cm)²A photoelectrode and a dye-sensitized solar cell were produced by the same procedure as in Example 1 except that the layer thickness was 15 μm. In this case, the application, drying, and firing of the slurry 1 on the transparent electrode 1 were repeated three times.
[0089]
(Comparative Example 2)
A slurry containing a high concentration of P25 at a high concentration (P25 content; 40% by mass; hereinafter, slurry 5 and the same) except that the amount of solvent used in Example 1 was reduced. Prepared). And only this slurry 5 is used, and the semiconductor electrode which consists of only one layer (the area of a light-receiving surface; 1.0 cm)²A photoelectrode and a dye-sensitized solar cell were produced by the same procedure as in Example 1 except that the layer thickness was 15 μm. In this case, the application, drying, and firing of the slurry 1 on the transparent electrode 1 were performed only once.
[0090]
(Comparative Example 3)
A semiconductor electrode composed of only one layer using only the slurry 4 used in Example 1 (light receiving surface area; 1.0 cm)²A photoelectrode and a dye-sensitized solar cell were produced by the same procedure as in Example 1 except that the layer thickness was 15 μm. In this case, the application, drying, and firing of the slurry 4 on the transparent electrode 1 were repeated three times.
[0091]
(Comparative Example 4)
A semiconductor electrode composed of only one layer using only the paste 1 used in Example 3 (light receiving surface area; 1.0 cm)²A photoelectrode and a dye-sensitized solar cell were prepared by the same procedure as in Example 1 except that the layer thickness was 12 μm. In this case, application, drying, and firing of the paste 1 on the transparent electrode 1 were performed by repeating three times.
[0092]
(Comparative Example 5)
A semiconductor electrode consisting of only one layer using only the paste 4 used in Example 4 (light receiving surface area; 1.0 cm)²A photoelectrode and a dye-sensitized solar cell were prepared by the same procedure as in Example 1 except that the layer thickness was 12 μm. In this case, the application, drying, and firing of the paste 4 on the transparent electrode 1 were performed by repeating three times.
[0093]
(Comparative Example 6)
A semiconductor electrode consisting of only one layer using only the paste 2 used in Example 1 (light receiving surface area; 1.0 cm)²A photoelectrode and a dye-sensitized solar cell were prepared by the same procedure as in Example 1 except that the layer thickness was 12 μm. In this case, application, drying, and baking of the paste 2 on the transparent electrode 1 were performed by repeating three times.
[0094]
(Comparative Example 7)
Using the colloidal solution 1 and the colloidal solution 2 prepared in Example 3, the mass ratio of P27 and P56 was P27: P56 = 7: 3 (P27 content; 8.4% by mass, P112 content) Amount: 3.6% by mass, hereinafter referred to as paste 8). In addition, a paste in which the mass ratio of P27 and P56 was set to P27: P56 = 1: 1 using the colloid solution 1 and colloid solution 2 prepared in Example 3 (P27 content; 6 mass%, P56 content) Amount: 6 mass%, hereinafter referred to as paste 9). Furthermore, using the colloidal solution 2 prepared in Example 3, a paste containing only P56 (P56 content; 100 mass%, hereinafter referred to as paste 10) was prepared.
[0095]
Then, the innermost layer 21 is formed using the paste 8, the inner layer 23 is formed using the paste 2, the outermost layer 22 is formed using the paste 10, and a semiconductor electrode composed of three layers ( Area of light receiving surface: 1.0 cm²A photoelectrode and a dye-sensitized solar cell were prepared by the same procedure as in Example 1 except that the layer thickness was 12 μm.
[0096]
(Comparative Example 8)
Using the paste 1 consisting only of P27 prepared in Example 3, the innermost layer 21 was formed by repeating application by screen printing on the transparent electrode 1, drying and baking twice. Furthermore, the outermost layer 22 was formed by coating, drying, and baking by screen printing on the innermost layer 21 using the paste 4 made of only P198 prepared in Example 4.
[0097]
Then, by the same procedure as in Example 1, a semiconductor electrode having the same configuration as the semiconductor electrode 2 shown in FIG. 1 on the transparent electrode 1 (light receiving surface area; 1.0 cm)²12 μm, the thickness of the innermost layer 21; 8 μm, the thickness of the outermost layer 22; 4 μm).
[0098]
[Battery characteristics test]
A battery characteristic test was performed, and the energy conversion efficiency η of the dye-sensitized solar cells of Examples 1 to 7 and Comparative Example 1 was measured. The battery characteristic test was performed using a solar simulator (trade name; “WXS-85-H type” manufactured by Wacom) and 100 mW / cm from a xenon lamp through an AM filter (AM-1.5).²It was performed by irradiating the simulated sunlight. The current-voltage characteristics were measured using an IV tester, and the open circuit voltage (Voc / V) and short circuit current (Isc / mA · cm) were measured.^-2), Fill factor (F.F.) and energy conversion efficiency (η /%). Table 1 shows the configuration of the photoelectrodes provided in each of the dye-sensitized solar cells of Examples 1 to 7 and Comparative Examples 1 to 8 and the results of the battery characteristic test.
[0099]
[Table 1]

[0100]
As is clear from the results shown in Table 1, the energy conversion efficiencies η of the dye-sensitized solar cells of Examples 1 to 6 are the dye-sensitized solars of Comparative Examples 1 to 8 corresponding to each. It was confirmed that the value was higher than the energy conversion efficiency η of the battery.
[0101]
【The invention's effect】
As described above, according to the present invention, since a high light confinement effect can be obtained in the semiconductor electrode constituting the photoelectrode, a photoelectrode having an excellent incident light utilization rate can be constituted. . Moreover, the dye-sensitized solar cell which has the outstanding energy conversion efficiency can be comprised by using this photoelectrode.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a first embodiment of a photoelectrode of the present invention.
FIG. 2 is a schematic enlarged cross-sectional view of a portion of a region 100 shown in FIG.
3 is a schematic sectional view showing a dye-sensitized solar cell including the photoelectrode shown in FIG. 1. FIG.
FIG. 4 is a schematic cross-sectional view showing the internal structure of a semiconductor electrode according to a second embodiment of the photoelectrode of the present invention.
FIG. 5 is a schematic cross-sectional view showing the internal structure of a semiconductor electrode according to a third embodiment of the photoelectrode of the present invention.
FIG. 6 is a schematic cross-sectional view showing the internal structure of a semiconductor electrode according to a fourth embodiment of the photoelectrode of the present invention.
7 is a schematic cross-sectional view showing another embodiment of the photoelectrode shown in FIG. 1. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Transparent electrode, 2 ... Semiconductor electrode, 3 ... Transparent electrically conductive film, 4 ... Board | substrate 10, 11, 12, 13, 14 ... Photoelectrode, 20 ... Dye-sensitized solar cell, 21 ... Innermost layer, 22 ... outermost layer, 63 ... inner layer, 100 ... partial region of photoelectrode 10, CE ... counter electrode, E ... electrolyte, F1, F2, F3 ... light receiving surface, F22 ... back surface of semiconductor electrode 2, L10 ... incident light , L12 ... scattered light, P1 ... oxide semiconductor particles, P2 ... sensitizing dye, P3 ... oxide semiconductor particles, P4 ... oxide semiconductor particles, S ... spacer.

Claims (4)

A photoelectrode having a semiconductor electrode having a light receiving surface and a transparent electrode disposed adjacent to the light receiving surface,
The semiconductor electrode is composed of a plurality of layers of three or more layers,
Each of the plurality of layers includes oxide semiconductor particles as a semiconductor material, and
The average particle diameter of the oxide semiconductor particles contained in each layer is from the innermost layer disposed at the position closest to the transparent electrode to the outermost layer disposed at the position farthest from the transparent electrode. Has increased ,
The oxide semiconductor particles are composed of small particles having an average particle diameter of 5 to 100 nm and large particles having an average particle diameter exceeding 100 nm,
The photoelectrode characterized in that the blending ratio of the large-diameter particles to the total amount of the small-diameter particles and the large-diameter particles increases from the innermost layer to the outermost layer . A photoelectrode having a semiconductor electrode having a light receiving surface and a transparent electrode disposed adjacent to the light receiving surface,
The semiconductor electrode is composed of a plurality of layers of three or more layers,
Each of the plurality of layers includes oxide semiconductor particles as a semiconductor material, and
The average particle diameter of the oxide semiconductor particles contained in each layer is from the innermost layer disposed at the position closest to the transparent electrode to the outermost layer disposed at the position farthest from the transparent electrode. Has increased ,
The oxide semiconductor particles contained in each of the plurality of layers excluding the innermost layer are composed of small particles having an average particle size of 5 to 100 nm and large particles having an average particle size of more than 100 nm,
The oxide semiconductor particles contained in the innermost layer are the small-diameter particles,
The mixing ratio of the large particle to the total amount of the small particle and the large particle is increased from the layer arranged closest to the innermost layer to the outermost layer among the plurality of layers. photoelectrode that it is possible, and characterized. The average particle diameter of the oxide semiconductor particles in the outermost layer is 50 to 500 nm,
And claims the difference between the average particle diameter of the oxide semiconductor particles in the mean particle size and the innermost layer of the oxide semiconductor particles in the outermost layer to be 10 to 400 nm, characterized by The photoelectrode according to 1 or 2 . A photoelectrode having a semiconductor electrode having a light-receiving surface and a transparent electrode disposed adjacent to the light-receiving surface of the semiconductor electrode, and a counter electrode, the semiconductor electrode and the counter electrode being interposed via an electrolyte A dye-sensitized solar cell disposed opposite to each other,
The said photoelectrode is a photoelectrode in any one of Claims 1-3 , The dye-sensitized solar cell characterized by the above-mentioned.

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