JPH07176773A - Photoelectric transducer and its manufacturing method - Google Patents

Abstract

PURPOSE:To improve the photoelectric energy transducing efficiency of a photoelectric transducer by providing an electron migration layer between a color carrier semiconductor layer and a counter electrode and enabling a surface carrying the dyestuff of the dyestuff carrying semiconductor layer to have recessed and projecting parts. CONSTITUTION:The element is provided with a transparent conductor layer 32 and a dyestuff carrying semiconductor layer 33 formed on one surface of the transparent conductor layer 32 and a dyestuff sensitization electrode 31 is formed by both of them. Also, a counter electrode 35 opposing the dyestuff carrying semiconductor layer 33 is formed and an electron migration layer 34 is provide between the dyestuff carrying semiconductor layer 33 and the counter electrode 35. Further, a surface where the dyestuff of the dyestuff carrying semiconductor layer 33 is carried is formed to have recesses and projections. Therefore, the surface area per projection area in lamination direction is large. Therefore, the number of projection area in lamination direction of dyestuff to be carried increases, thus increasing the number of dyestuff per projection area for absorbing light and exchanging electrons with a semiconductor and hence improving photoelectric transducing efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion element using a dye-sensitized (semiconductor) electrode in which a dye is carried on the surface of a semiconductor layer, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, as a photoelectric conversion element using a dye-sensitized electrode in which a dye is carried on the surface of a semiconductor layer,
A wet type is known in which a dye-supporting layer portion of an electrode and a counter electrode are immersed in an electrolytic solution. For example, when the semiconductor of the semiconductor layer is n-type, an anode photocurrent flows through the semiconductor layer, and electromotive force is generated. In this case, since the energy level of the lowest unoccupied orbit of the dye is higher than that of the conduction band of the semiconductor, the electrons of the excitation level of the excited dye move to the conduction band of the semiconductor. At the same time, cations of the dye are generated, but the electrons from the electrolyte enter the ground level of the cation of the dye,
The dye is reduced.

As an example of a material for a wet photoelectric conversion element,
Porous polycrystalline titanium dioxide prepared by a sol-gel method and an electrodeposition method is used for the semiconductor layer, and cis-di (thiocyanato) -N, N-bis (2,2'-dipyridyl-4, 4'-dicarboxylic acid) -ruthenium (I
I) dihydrate or cis-dicyano-N, N-bis (2,2
2'-dipyridyl-4,4'-dicarboxylate) ruthenium (II) trihydrate or cis-dibromo-N, N
-Bis (2,2'-dipyridyl-4,4'-dicarboxylate) ruthenium (II) or cis-diiodo-
Using N, N-bis (2,2′-dipyridyl-4,4′-dicarboxylate) ruthenium (II) (Journal of American Chemical Society, Vol. 115, pages 6382 to 6390 (1993)
Year)).

As another example, porous polycrystal titanium dioxide prepared by a sol-gel method and an electrodeposition method is used for a semiconductor layer and RuL ₂ (μ- (CN) Ru (C
N) L ' ₂ ) ₂ (where L is 2,2'-bipyridine-4,
4'-dicarboxylic acid, L'is 2,2'-bipyridine) (Nature 353, pp. 737 to 7)
40 pages (1991)).

As still another example, titanium dioxide single crystal is used for the semiconductor layer and [Ru (4,7-dimethyl-1,10-phenanthroline) ₃ ] ²⁺ is used as the dye, and ZnO single crystal is used for the semiconductor layer. A crystal or a sintered body is used with rose bengal as a dye, and SnO ₂ is used as a semiconductor layer.
Thin film, one using [Ru (bpy) ₃ ] ²⁺ as a dye, In ₂ O ₃ used in a semiconductor layer, and N, N′− as a dye
Those using distearyl oxacyanine (above, Chemical Review No. 33, "New development of organic photochemistry-electron transfer reaction", Academic Society Publishing Center page 281 (1982)) and the like can be mentioned.

On the other hand, as a dry photoelectric conversion element, there is known one having a structure in which an electrode formed by supporting a dye on a semiconductor layer is in contact with a counter electrode at a dye portion. As an example of this, a ZnO sputtering film is used for the semiconductor layer and a merocyanine dye is used as the dye (Japanese
Journal of Applied Physics Vol. 19, pages L683 to L685 (1980)), using copper phthalocyanine as a semiconductor layer and a perylene derivative as a dye (Chemical Society of Japan, pages 962 to 967 (1990)). Etc.

Among these examples, the sol
Porous polycrystalline titanium dioxide prepared by gel method and electrodeposition method was used, and cis-di (thiocyanato)-
Using N, N-bis (2,2′-dipyridyl-4,4′-dicarboxylic acid) -ruthenium (II) dihydrate (Journal of American Chemical Society, Vol. 115, pages 6382 to 6390) (19
1993)), or porous polycrystal titanium dioxide prepared by a sol-gel method and an electrodeposition method for the semiconductor layer, and RuL ₂ (μ- (CN) Ru (CN) L ′ ₂ ) as a dye.
₂ (where L is 2,2′-bipyridine-4,4′-dicarboxylic acid and L ′ is 2,2′-bipyridine) (Nature 353, pp. 737 to 740 (1
991)) and the like improve the photoelectric conversion efficiency by adsorbing a dye on the porous surface of the semiconductor layer and increasing the number of adsorbing dyes per projected area of the porous surface of the semiconductor layer in the stacking direction. is there.

[0008]

However, even in the photoelectric conversion element using the above-mentioned conventional electrode having a structure in which a dye is supported on the semiconductor layer, the number of supported dyes per projected area of the semiconductor layer is sufficient. In addition, there was a problem that the photoelectric conversion efficiency was small. The present invention has been made in order to solve the above problems of the conventional example, and an object thereof is to provide a photoelectric conversion element having a large photoelectric conversion efficiency and a method for manufacturing the same.

[0009]

In order to achieve the above object, the photoelectric conversion device of the present invention is a dye-carrying device in which a dye is carried on a transparent conductor layer and a semiconductor layer formed on the transparent conductor layer. An electrode having a semiconductor layer, a counter electrode facing the dye-supporting semiconductor layer, and an electron transfer layer provided between the dye-supporting semiconductor layer and the counter electrode, wherein the dye of the semiconductor layer is The supported surface is configured to have irregularities. In the above structure, the semiconductor layer preferably contains a polycrystalline semiconductor. Further, in the above structure, the unevenness preferably has a period of 0.4 μm or less. Further, in the above structure, the semiconductor layer preferably contains titanium dioxide. Further, in the above structure, the semiconductor layer preferably contains a porous semiconductor. On the other hand, the method for producing a photoelectric conversion element of the present invention is an electrode having a transparent conductor layer and a dye-carrying semiconductor layer in which a dye is carried on a semiconductor layer formed on the transparent conductor layer, and the dye-carrying member. A counter electrode facing the semiconductor layer, and an electron transfer layer provided between the dye-carrying semiconductor layer and the counter electrode,
A method of manufacturing a photoelectric conversion element having a surface on which a dye of the semiconductor layer is uneven, wherein the surface of the semiconductor layer on which the dye is carried is prior to carrying the dye, at least one kind of laser light is used. It is configured to be photo-dissolved in the electrolytic solution by the exposure of the interference fringes and be processed into unevenness having a predetermined period. In the above configuration, the predetermined cycle of the unevenness is 0.
It is preferably 4 μm or less.

[0010]

When the semiconductor is an n-type, an anode photocurrent flows through the semiconductor and an electromotive force is generated. In this case, since the energy level of the lowest unoccupied orbit of the dye is higher than that of the conduction band of the semiconductor, the excited dye injects excited electrons into the conduction band of the semiconductor, and the resulting cations of the dye are (or (Directly from the counter electrode) is reduced by electrons. On the other hand, when the semiconductor is p-type, a cathode photocurrent flows through the semiconductor layer and an electromotive force is generated. In this case, since the energy level of the highest occupied molecular orbit of the dye is lower than that of the valence band of the semiconductor, electron transfer from the valence band of the semiconductor to the excited dye occurs, and the resulting anion of the dye is excited. The electrons are oxidized by moving to the electron charge transport layer (or directly to the counter electrode). (Electrochemistry Vol. 49, pp. 423-42
Page 6 (1981))

In the photoelectric conversion device of the present invention, the surface of the semiconductor layer on which the dye is carried is uneven, and the surface area per projected area in the stacking direction is large. Therefore, the number of dyes carried per projected area in the stacking direction also becomes large. Therefore, the number of dyes that absorb light and exchange electrons with the semiconductor per the projected area is increased, and the photoelectric conversion efficiency is improved.
Further, by providing the irregularities on the surface of the semiconductor layer on which the dye is carried with a predetermined period and setting the period to 0.4 μm or less, the light reflection at the semiconductor-dye interface causes the periodic irregularity of the interface ( Suppressed for wavelengths larger than 0.4 μm (Nature 244, pp. 281-2)
82 (1973) and Optica Actor Vol. 29, 1004 (1982)), the photoelectric conversion efficiency is further increased.

Since the polycrystalline semiconductor is relatively inexpensive and can be easily manufactured, the photoelectric conversion element becomes inexpensive by including the polycrystalline semiconductor in the semiconductor layer. Also,
Titanium dioxide is an n-type semiconductor with a wide bandgap and is particularly stable as a photoanode in an electrolytic solution. Therefore, by including titanium dioxide in the semiconductor layer, titanium dioxide in the electrode is photo-corroded by visible light. Without doing so, the durability of the photoelectric conversion element is improved. In addition, since the semiconductor layer contains the porous semiconductor, the number of dyes carried per projected area in the stacking direction is further increased, and the photoelectric conversion efficiency is further increased.

On the other hand, in the method of manufacturing a photoelectric conversion element of the present invention, the semiconductor surface is etched by photodissolving the semiconductor in an electrolytic solution. Since the exposure is performed by the interference fringes of the laser light, the interference fringes can be formed at very small intervals, and the laser light does not pass through the electrolytic solution but passes through the inside of the semiconductor so that the exposure without fluctuation by the electrolytic solution is possible. You can also do Therefore, it becomes possible to form irregularities of 0.4 μm or less on the semiconductor surface.

[0014]

EXAMPLE FIG. 1 shows the configuration of an example of the photoelectric conversion element of the present invention. In FIG. 1, the photoelectric conversion element of the present invention comprises a first conductive glass layer 32 (transparent conductor layer), a dye-carrying semiconductor layer 33 formed on one surface of the first conductive glass layer 32, The second conductive glass layer 37 includes a platinum layer 36 formed on the surface of the second conductive glass layer 37 facing the dye-carrying semiconductor layer 33, and an electron transfer layer 34 provided between the dye-carrying semiconductor layer 33 and the platinum layer 36. To do. Here, the first conductive glass layer 32 and the dye-carrying semiconductor layer 33 constitute the dye-sensitized electrode 31. In addition, the second conductive glass layer 37 and the platinum layer 36
And constitute the counter electrode 35. Further, lead wires 41 and 42 are connected to the first and second conductive glass layers 32 and 37, respectively, and the electromotive force generated by this photoelectric conversion element is output. The first and second conductive glass layers 32 and 37 are the dye-carrying semiconductor layer 33 side and the platinum layer 3 respectively.
A transparent conductive film is formed on the surface on the 6 side.

In the photoelectric conversion device having the above structure, the dye in the dye-carrying semiconductor layer 33 of the dye-sensitized electrode 31 is photoexcited by sunlight, and electrons are injected into the semiconductor conduction band. At the same time, cations of the dye are generated, and the generated cations are reduced by the electrons from the electron transfer layer 34 to generate electromotive force.

The dye-carrying semiconductor layer 33 is a semiconductor layer formed on one surface of the first conductive glass layer 32, and the dye is carried on the surface of the semiconductor layer. It has been subjected. When the shape of the concavo-convex processing is one-dimensional periodic concavo-convex and the cross-sectional shape is zigzag symmetrical with respect to the periodic direction, the aspect ratio (groove depth / groove period) is 1/2. If so, its surface area is √2 times as large as that of a flat surface. Further, the shape of the uneven processing is a two-dimensional periodic unevenness, and two zigzag patterns (aspect ratio 1/2) similar to the above are combined so that their lattice vectors are orthogonal to each other. In that case, the surface area is √3 times that of a flat surface. As the concavo-convex processing method, for example, a mechanical processing method including fixed-grain or free-grinding abrasive grain processing and processing with a cutting tool, a chemical processing method such as etching, a photochemical processing method such as photoetching, and an electrochemical method. By mechanical processing, electron beam processing, ion beam processing,
A method such as plasma processing may be used. In this example, a method based on photochemical processing was used.

First and second conductive glass layers 32 and 37
For example, a layer containing fluorine ion-doped SnO ₂ or a layer containing ITO can be used as the material. Further, as the material of the semiconductor layer 33, for example, a layer containing titanium dioxide, a layer containing ZnO, a layer containing SnO ₂ , and In ₂ O
3 ₃ including a layer, the layer including copper phthalocyanine can be a layer or the like including a InP. The semiconductor may be either n-type or p-type, and its state may be, for example,
It may be in a single crystal state, a polycrystalline state, or the like. Semiconductor layer 3
As a method of forming 3, a crystal growth method, a sol-gel method, an electrodeposition method, a vapor deposition method, a sputtering method, or the like can be used. As a method for forming a porous semiconductor layer, for example, a method such as sintering, foaming, hydration, elution of a soluble phase, gelation, extrusion through a large number of nozzles or a knitted die can be used. .

As the dye, for example, cis-di (thiocyanato) -N, N-bis (2,2'-dipyridyl-
4,4'-dicarboxylic acid) ruthenium (II) dihydrate, cis-dicyano-N, N-bis (2,2'-dipyridyl-4,4'-dicarboxylate) ruthenium (I
I) trihydrate, cis-dibromo-N, N-bis (2,2
2'-dipyridyl-4,4'-dicarboxylate) ruthenium (II), cis-diiodo-N, N-bis (2,2'-dipyridyl-4,4'-dicarboxylate) ruthenium (II), RuL ₂ (μ- (CN) Ru
(CN) L ' ₂ ) ₂ (where L is 2,2'-bipyridine-
4,4'-dicarboxylic acid, L'is 2,2'-bipyridine), [Ru (4,7-dimethyl-1,10-phenanthroline) ₃ ] ²⁺ , rose bengal, [Ru (bp
y) ₃ ] ²⁺ , N, N′-distearyloxacyanine can be mentioned. These are, for example, adsorption method by adsorption at the semiconductor / dye solution interface, casting method, Langmuir-Blodgett method, electrodeposition method, chemical modification method by chemical reaction between active group on semiconductor and dye, vapor deposition method, etc. Due to
It can be supported on the semiconductor layer 33.

As the counter electrode 35, for example, an electrode containing transparent conductive glass coated with a transparent conductive film such as a fluorine ion-doped SnO ₂ film, an electrode in which the glass layer of the transparent conductive glass is coated with platinum, a carbon electrode, A metal electrode or the like can be used. Further, as the electron transfer layer 34, for example, I
^3- / I ^- and consists consisting electrolyte layer or a solid electrolyte containing a redox pair such as quinone / hydroquinone may be a layer or the like.

Next, 0.4 μ is applied to the surface of the semiconductor layer.
A method of forming irregularities having a period of m or less will be described. First, there is a method of forming a pattern using a photosensitive material and etching the pattern. As a pattern forming method using a photosensitive material, there are, for example, a method of direct drawing exposure on the photosensitive material, a method of mask exposure, and the like. In the former case, a method by electron beam drawing exposure, a method by ion beam drawing exposure, a method by holographic exposure utilizing the coherence of laser light, and the like can be mentioned. In the latter case, there are methods such as equal size transfer using a full size mask and reduction transfer using an enlarging mask. Further, in the case of equal-magnification transfer, there are a contact exposure method using deep ultraviolet rays or the like as a light source, a proximity exposure method using X-rays or the like as a light source, and an equal-magnification projection exposure using an electron beam or the like as a light source. In this case, an excimer laser such as ArF laser or KrF laser, a method of reduction projection exposure using an electron beam or the like as a light source, and the like can be mentioned. On the other hand, as a method that does not use a photosensitive material, there is, for example, a method of photodissolving a semiconductor layer in an electrolytic solution, and as an exposure method, for example, the same method as described above can be used.

Next, the method for manufacturing the photoelectric conversion element of the present invention will be described in detail. First, the processed surface of the semiconductor layer formed on the first conductive glass layer 32 is immersed in an electrolytic solution together with the counter electrode 35, and then the processed surface is exposed to at least one kind of laser light interference fringes to expose the semiconductor layer. Photo-melt the processed surface of
A surface having irregularities having a period of 0.4 μm or less is formed. Then, a dye-carrying semiconductor layer 33 is formed by supporting a dye on the uneven surface of the semiconductor layer, and the first conductive glass layer 32 is formed.
And the dye-carrying semiconductor layer 33 constitute the dye-sensitized electrode 31. A photoelectric conversion element is configured by disposing the electron transfer layer 34 between the dye-supporting semiconductor layer 33 of the dye-sensitized electrode 31 and the platinum layer 36 of the counter electrode 31. In the method for manufacturing a photoelectric conversion element of the present invention, when two or more types of interference fringes of laser light are used, the bright and dark intervals in each type and the direction of the lattice vector may be the same or different, and each interference The stripe exposure times may be the same or different.

As the laser light, for example, He—Cd ⁺ laser light, excimer laser light, N ₂ laser light, F ₂ laser light or the like can be used. He-Cd ⁺ laser light is
It is excellent in that it consumes less power and is compact.
In addition, excimer laser light, N ₂ laser light, F ₂ laser light, and the like are excellent in that the unevenness having a short wavelength and a smaller period can be formed. As the electrolytic solution, for example, a solution containing an I ^{3 −} / I ⁻ redox system, a solution containing a quinone / hydroquinone redox system, or the like can be used.

The present invention will be described in more detail with reference to specific examples. (Experimental Example 1) First, Journal of American
Chemical Society, Vol. 115, pages 6382 to 6390 (1993) (Me).
According to the method A), polycrystalline T is formed on the conductive glass substrate.
An iO ₂ film (thickness of about 8 μm) was formed. The method will be described below. First, Journal of Physical Chemistry, Vol. 94, page 8720 (1990)
A colloidal solution of titanium dioxide was prepared by hydrolysis of titanium isopropoxide as described below according to the method described in. 125 under dry nitrogen atmosphere
mL of titanium tetraisopropoxide (Aldrich) was placed in a dropping funnel containing 20 mL of 2-propanol. This mixture was added dropwise to 750 mL of distilled deionized water over 5 minutes with vigorous stirring. While continuing stirring, 5.3 mL of 70% nitric acid was added 5 minutes after the dropping, and stirring was further continued at 80 ° C. for 8 hours. Thus, 2-propanol was removed by evaporation, and about 700 mL of titanium dioxide colloidal sol was obtained.

Then, this sol was kept at 230 to 240 ° C. in an autoclave for 12 hours, and then water was evaporated at 25 ° C. under reduced pressure to make the viscosity large. afterwards,
Carbowax M-2 with 40% by weight of titanium dioxide
After adding 0000 (weight ratio of titanium dioxide to the whole is 20%), it is coated on a conductive glass substrate (made by Asahi Glass, fluorine-doped SnO ₂ overcoating, 85% transmission of visible light, sheet resistance 80 / square). Under the air 4
Heated at 50 ° C. for 30 minutes. Further, electrodeposition of several layers of titanium dioxide was carried out as follows according to the method described in Journal of Electric Ectro Analytical Chemistry, Vol. 346, pages 291 to 307 (1993). The electrodeposition is 500 mC at a current value of 250 μA / cm ² from a 50 mM TiCl ₃ aqueous solution at pH 2.5.
/ Cm ² of electric charge (0.25 mg of TiO ₂ / cm
² was electrodeposited). The electrolyte is 15% Ti in HCl
A Cl ₃ solution (pretreated with zinc amalgam for several days) was used and adjusted under an Ar atmosphere. The pH was adjusted with degassed NaHCO ₃ or Na ₂ CO ₃ . The obtained laminated film was heated at 450 ° C. to obtain a polycrystalline TiO ₂ film. When the cross section was observed with an electron microscope, the thickness was about 8 μm.

Next, using this film as an electrode, periodic surface irregularity processing was performed by photodissolution in an electrolytic solution by interference exposure of laser light. FIG. 2 shows a schematic configuration of the laser light interference exposure apparatus used in this embodiment. In FIG. 2, the laser light interference exposure apparatus is an air spring type vibration isolation table 1.
1, the He-Cd ⁺ laser oscillator 12 (3
25 nm, about 2 mW) of the emitted light beam is split by the beam splitter 15, and the split light beam is divided by the lens 1 respectively.
After expanding to a diameter of 2-3 cm with No. 7, T of the photoelectrochemical cell 18
It is configured to match on the iO ₂ film electrode. The photoelectrochemical cell 18 for patterning has a structure as shown in FIG. That is, the conductive glass layer 26 and the film 25 were used as one electrode, and the window 21 of the quartz plate was attached through the silicone rubber gasket 22. A copper wire was used as the reference electrode 23, and a platinum wire was used as the counter electrode 24. A neutral sodium perchlorate aqueous solution was used as the electrolytic solution to be placed in this cell, and the electrode potential was 0.5 Vv.
s. Patterning was performed once with Ag. When exposure was performed for 45 minutes, it was confirmed that substantially uniform periodic unevenness was formed over a range of about 1.5 × 1.5 cm ² . The obtained pattern was scanned with an electron microscope (S
When observed by EM), it was confirmed that irregularities having a period of about 0.4 μm were generated.

The surface of the polycrystalline TiO ₂ film on the electrically conductive glass, which had been subjected to the periodic unevenness treatment, obtained as described above was subjected to Journal of American Chemical Society, Vol. 115, pages 6382 to 6390 (19).
1993), dyes of 3 × 10 ⁻⁴ M
After immersing in a dry ethanol solution (temperature of about 80 ° C) for 4 hours, pulling it up under an argon stream, TiO ₂
A dye was carried on the film surface to form a dye-carrying semiconductor layer.

The obtained electrode was stored in dry ethanol. Using this electrode as the dye-sensitized electrode 31, an example of the photoelectric conversion element shown in FIG. 1 (hereinafter referred to as element 1) was constructed. The electron transfer layer 34 was formed in the gap between the dye-supporting semiconductor layer 33 and the platinum layer 36 by using a capillary force.

Further, as the semiconductor layer 33, polycrystalline Ti is used.
When O ₂ is used, and the surface on which the dye is carried is porous and has a normal mechanical engraving grating (hereinafter referred to as element 2), and when polycrystalline TiO _{2 is used} as the semiconductor layer.
In the case where the surface on which the dye is carried is porous and smooth (hereinafter, referred to as element 3), a photoelectric conversion element having the configuration shown in FIG. 1 was similarly prepared. As a dye, cis-di (thiocyanato) -N, N-bis (2,2
2'-dipyridyl-4,4'-dicarboxylic acid) -ruthenium (II) dihydrate is used, and its adsorption to the semiconductor layer is described in Journal of American Chemical Society, Vol. 115, pp. 6382 to 6390 (1993).
Electron Transfer Layer 3
A solution of [Li] = 0.3M and [I ₂ ] = 0.03M in acetonitrile / 3-methyl-2-oxazolidinone mixed solvent (volume ratio 90/10) was used as No. 4 (electrode area of dye-sensitized electrode 1). Is 0.4 cm ² ).

The elements 1, 2 and 3 obtained as described above were respectively subjected to AM1.5 pseudo sunlight (intensity 96.0 m).
When the photoelectric conversion efficiency was measured using W) as a light source, it was 14.4% for element 1, 13.5% for element 2 and 9.9% for element 3, respectively, which are large values. It was confirmed.

(Experimental Example 2) The dye was changed to RuL ₂ (μ- (C
N) Ru (CN) L' ₂ ) ₂ (wherein L is 2,2'-bipyridine-4,4'-dicarboxylic acid and L'is 2,2
-Bipyridine. ) And [Tetrapropylammonium iodide] = 0.
5M, [KI] = 0.02M, [I ₂ ] = 0.03M acetonitrile / ethylene carbonate mixed solvent (volume ratio 10 /
80) Photoelectric conversion elements 1, 2 and 3 were similarly prepared using the solution. Photoelectric energy conversion efficiency was measured to be 10.3% for element 1 and 9.7 for element 2.
%, And it was confirmed that they were large values, respectively, compared with 7.1% of the element 3. Incidentally, cis-di (thiocyanato) -N, N-bis (2,2'-dipyridyl-
The synthesis of 4,4′-dicarboxylic acid) -ruthenium (II) dihydrate is carried out by the method described in Journal of American Chemical Society, Vol. 115, page 6382 to page 6390 (1993), and R
uL ₂ (μ- (CN) Ru (CN) L ′ ₂ ) ₂ (however, L
Is 2,2'-bipyridine-4,4'-dicarboxylic acid and L'is 2,2-bipyridine. ) Is synthesized by Helvetica Kimika Actor Vol. 73, pp. 1788 to 1
It was carried out by the method described on page 803 (1990).

Experimental Example 3 The semiconductor layer 3 in Experimental Example 1
In addition to the periodic concavo-convex processing performed on the surface of No. 3, the same pattern processing was performed by rotating the TiO ₂ film by 90 degrees on the processed surface while keeping the state of the laser beam. The exposure time was the same as in Experimental Example 1. As a result, a substantially uniform concave-convex pattern was produced over a range of about 1.5 × 1.5 cm ² . When the obtained pattern was observed by SEM, it was confirmed that a concavo-convex pattern in which grooves having a period of about 0.4 μm were orthogonal to each other was formed. Using the TiO ₂ film thus obtained,
Other conditions were the same as in Experimental Example 1, and a photoelectric conversion element having the same structure as that shown in FIG. 1 was prepared. (Hereinafter, referred to as element 4.).

As the dye of the dye-supporting semiconductor layer 33, cis-di (thiocyanato) -N, N-bis (2,2'-dipyridyl-4,4'-dicarboxylic acid) -ruthenium (I
I) Dihydrate was used. AM1.5 pseudo sunlight (intensity 9
When the photo-electric energy conversion efficiency of the device 4 was measured using 6.0 mW) as a light source, the value was 18.3%, which was significantly higher than 9.9% of the device 3 and the device 1 It was even higher than 14.4%.

[0033]

As described above, according to the photoelectric conversion element of the present invention, since the surface of the semiconductor layer is processed to be uneven, the surface area around the projected area in the stacking direction is increased.
The number of dyes that absorb light carried on the surface and exchange electrons with the semiconductor increases. As a result, there is an effect that the photoelectric conversion efficiency is significantly improved as compared with the conventional one. In addition, by providing the irregularities on the surface of the semiconductor layer with a predetermined period and setting the period to 0.4 μm or less, the light reflection at the semiconductor-dye interface causes the periodic irregularity of the interface (0.4 μm or less). Since it is suppressed for a larger wavelength, the photoelectric conversion efficiency can be further increased. Further, since a polycrystalline semiconductor can be manufactured easily at a relatively low cost, the photoelectric conversion element can be made inexpensive by including the polycrystalline semiconductor in the semiconductor layer. Further, titanium dioxide is an n-type semiconductor having a large band gap and is particularly stable as a photoanode in an electrolytic solution. Therefore, by including titanium dioxide in the semiconductor layer, the titanium dioxide in the electrode is exposed to visible light. The durability of the photoelectric conversion element can be improved without photocorrosion. Further, since the semiconductor layer includes the porous semiconductor picture, the number of dyes carried per projected area in the stacking direction is further increased, and the photoelectric conversion efficiency can be further increased.

On the other hand, according to the method of manufacturing a photoelectric conversion element of the present invention, the semiconductor surface is etched by photodissolution of the semiconductor in the electrolytic solution, and the exposure is performed by the interference fringes of the laser light. It can be very small. As a result, it becomes possible to form irregularities of 0.4 μm or less on the semiconductor surface.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of an embodiment of a photoelectric conversion element of the present invention.

FIG. 2 is a diagram showing the configuration of an embodiment of a laser light interference exposure apparatus suitable for the method for manufacturing a photoelectric conversion element of the present invention.

FIG. 3 is a perspective view showing the configuration of the photoelectrochemical cell in FIG.

[Explanation of symbols]

11: Air spring type vibration isolation table 12: He-Cd ⁺ laser oscillation device 13: Laser light 14: Mirror 15: Beam splitter 16: Mirror-17: Lens 18: Photoelectrochemical cell 21: Quartz plate 22: Silicon rubber Gasket 23: Reference electrode 24: Counter electrode 25: Semiconductor part 26: Conductive glass part 31: Dye-sensitized electrode 32: First conductive glass layer 33: Dye-carrying semiconductor layer 34: Electron transfer layer 35: Counter electrode 36: Platinum layer 37: Second conductive glass layer 41: Lead wire 42: Lead wire

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuya Wakita 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Nobuo Sonoda, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (7)

[Claims] 1. An electrode having a transparent conductor layer and a dye-carrying semiconductor layer in which a dye is carried on a semiconductor layer formed on the transparent conductor layer, and a counter electrode facing the dye-carrying semiconductor layer. A photoelectric conversion element comprising: the dye-carrying semiconductor layer and an electron transfer layer provided between the counter electrode, wherein a surface of the dye-carrying semiconductor layer on which the dye is carried has unevenness. 2. The photoelectric conversion element according to claim 1, wherein the semiconductor layer contains a polycrystalline semiconductor. 3. The photoelectric conversion element according to claim 1, wherein the unevenness has a period of 0.4 μm or less. 4. The semiconductor layer comprises titanium dioxide.
5. The photoelectric conversion element according to any one of 3 to 3. 5. The semiconductor layer comprises a porous semiconductor.
5. The photoelectric conversion element according to any one of 4 to 4. 6. An electrode having a transparent conductor layer and a dye-carrying semiconductor layer in which a dye is carried on a semiconductor layer formed on the transparent conductor layer, and a counter electrode facing the dye-carrying semiconductor layer. A method for manufacturing a photoelectric conversion element comprising an electron transfer layer provided between the dye-carrying semiconductor layer and the counter electrode, wherein the dye-carrying surface of the semiconductor layer has irregularities, Before the dye is supported, the surface of the semiconductor layer on which the dye is supported is photo-dissolved in the electrolytic solution by exposure of at least one kind of laser light interference fringes, and processed into irregularities having a predetermined period. And a method for manufacturing a photoelectric conversion element. 7. The method for manufacturing a photoelectric conversion element according to claim 6, wherein the predetermined period of the unevenness is 0.4 μm or less.