JP2002141115A - Photoelectric conversion device, its manufacturing method, and solar battery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion device in which photoelectric conversion efficiency is enhanced by improving the transfer passage of charges such as electrons. SOLUTION: This photoelectric conversion device is equipped with a generating means 16 generating charges on incident light; and a needlelike semiconductor crystal 17 coming in contact with the generation means 16, and transferring one of generated charges to an electrode. Granular semiconductor crystal 18 is formed in the needlelike semiconductor crystal 17, and a coat material 24 is formed in the needlelike and granular semiconductors 17, 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion device, a method of manufacturing the same, and a solar cell, and more particularly to a photoelectric conversion device having a needle-like semiconductor crystal for transferring one of electric charges generated based on incident light to an electrode. The present invention relates to a photoelectric conversion device, a manufacturing method thereof, and a solar cell.

[0002]

2. Description of the Related Art Conventionally, as a method of converting light energy into electric energy, a solar cell using a semiconductor junction such as silicon or gallium-arsenic is generally used. Above all, a single-crystal silicon solar cell and a polycrystalline silicon solar cell using a pn junction of a semiconductor, and an amorphous silicon solar cell using a PIN junction are well known, and their practical use is progressing.

[0003] However, silicon solar cells are expensive to manufacture and consume a lot of energy in the manufacturing itself.
Long-term use is required to recover installation costs and energy consumption. It is mainly at this cost that the bottleneck of the current spread is.

On the other hand, in recent years, research on practical use of CdTe, CuIn (Ga) Se, and the like as second-generation thin-film solar cells has been advanced, but these materials have raised environmental and resource problems. .

As a method of manufacturing a solar cell without using a semiconductor junction such as silicon or gallium-arsenic, there is a method utilizing a photoelectrochemical reaction occurring at an interface between a semiconductor and an electrolyte solution. Solar cells are called wet solar cells, and are distinguished from dry solar cells manufactured using semiconductor junctions.

[0006] Metal oxide semiconductors such as titanium oxide and tin oxide used in wet solar cells can be manufactured at a lower cost than silicon, gallium-arsenic, etc. used in dry solar cells, and especially oxidized oxide semiconductors. Titanium is excellent in both photoelectric conversion characteristics and stability, and is expected as a future energy conversion material.

However, since a stable optical semiconductor such as titanium oxide has a wide band gap of 3 eV or more, only ultraviolet light, which is about 4% of sunlight, can be used. Instead, improvements are required.

Therefore, a photochemical cell (dye-sensitized solar cell) in which a dye is adsorbed on the surface of an optical semiconductor has been studied. In the early days, semiconductor single-crystal electrodes were used. The electrodes include titanium oxide, zinc oxide, cadmium sulfide, tin oxide and the like.

However, single-crystal electrodes have low efficiency because of the small amount of dye adsorbed and are expensive, and attempts have been made to make the semiconductor electrodes porous. Tsubomura et al. Reported that dyes were adsorbed on a semiconductor electrode made of porous zinc oxide with sintered fine particles to improve efficiency (NATURE, 261 (1976) p4)
02). Proposals for using a porous semiconductor electrode are disclosed in JP-A-10-112337 and JP-A-9-23.
No. 7641 discloses this.

Have reported that a dye and a semiconductor electrode were further improved to obtain a performance comparable to that of a silicon solar cell (J. Am. Chem. Soc. 115 (1993) 638).
2, U.S. Pat. No. 5,350,644). Here, a ruthenium-based dye is used as the dye, and anatase-type porous titanium oxide (TiO ₂ ) is used as the semiconductor electrode.

FIG. 11 is a schematic sectional view showing a schematic structure of a photochemical battery (hereinafter, referred to as a "Graetzel type cell") using a Graetzel type dye-sensitized semiconductor electrode. FIG.
In 1, 63 is an electrolytic solution, 62 is a light absorbing layer that absorbs incident light in the electrolytic solution 63, 61 is an anatase-type TiO ₂ fine particle conjugate formed inside the light absorbing layer 62,
Reference numeral 66 denotes a transparent electrode layer formed so as to cover the electrolytic solution 63. The light incident side is an anode, and the opposite side is a cathode. 64 is a glass substrate on which the transparent electrode layer 66 is formed.

Also, anatase type TiO_TwoFine particle conjugate
61 is TiO_TwoPorous shape with fine particles bonded to each other
It is a joined body. Further, the light absorption layer 62 is made of an anatase type.
TiO _TwoThe dye bonded to the surface of the fine particle bonded body 61
You.

Next, a method for manufacturing a Graetzel type cell will be described. First, a transparent electrode layer 65 is formed on a glass substrate 64. Then, anatase type Ti
An O ₂ particle bonded body 61 is formed. There are various types of this manufacturing method. Generally, a paste in which anatase-type TiO ₂ fine particles having a fine particle diameter of about 20 nm are dispersed is applied on the transparent electrode layer 65, and baked at 350 to 500 ° C. An anatase-type TiO ₂ fine particle bonded body 61 having a thickness of about 10 μm is formed.

At this time, when the anatase type TiO ₂ fine particles are joined to each other moderately, the porosity is about 50% and the lathness factor (substantial surface area / apparent surface area) is 1
An anatase-type TiO ₂ fine particle conjugate 61 having a film structure of about 000 is obtained.

Next, a light absorbing layer 62 is formed on the surface of the anatase-type TiO ₂ fine particle assembly 61. Various materials have been studied for the light absorbing layer 62, but a ruthenium complex or the like is generally used. When the glass substrate 64 on which the transparent electrode layer 65 and the anatase-type TiO ₂ fine particle bonded body 61 are formed is immersed in a solution in which the light absorbing layer 62 is dissolved and dried, the surface of the anatase-type TiO ₂ fine-particle bonded body 61
The light absorbing layer 62 is bonded.

As a solvent in which the light absorbing layer 62 is dissolved, ethanol, acetonitrile, or the like is used. This is because ethanol and the like dissolve the light absorbing layer 62 well,
The light absorbing layer 62 is made of an anatase-type TiO ₂ fine particle bonded body 61.
This is because it has a property that it does not hinder the adsorption to the surface and a property that it is electrochemically inactive even if it remains on the surface of the anatase-type TiO ₂ fine particle bonded body 61.

Next, similarly, a transparent electrode layer 66 is formed on the glass substrate 64. Then, on the surface of the transparent electrode layer 66,
Form a thin film such as platinum or graphite. This thin film acts as a catalyst for charge exchange in the redox. Then, a Graetzel type cell is manufactured by injecting the electrolytic solution 63 between the transparent electrode layers 65 and 66 or the like.

As a solvent for the electrolytic solution 63, acetonitrile, ethylene carbonate or the like is used. This is due to the fact that acetonitrile and the like are electrochemically inert,
This is because it has a property that a sufficient amount of the electrolyte can be dissolved. As the electrolyte, a stable ion redox pair such as I ⁻ / I ₃ ⁻ or Br ⁻ / Br ₃ ⁻ is used.

[0019] For example, I ^- / I ₃ ^- when making pairs, mixed ammonium salt of iodine and iodine. Thereafter, it is preferable to seal the Graetzel type cell with an adhesive or the like in order to impart durability.

Next, the operation principle of the Graetzel type cell will be described. As shown in FIG. 11, when light is incident on the Graetzel type cell from the transparent electrode layer 65 side, electrons are excited in the light absorbing layer 62 by the incident light, and the anatase Ti
It moves to the O ₂ fine particle bonded body 61 side. The light absorbing layer 62 which has lost the electrons and is in the oxidized state quickly receives the electrons from the iodine ions of the electrolytic solution 63 and is reduced to return to the original state.

The electrons that have moved toward the anatase-type TiO ₂ fine particle bonded body 61 move through the anatase-type TiO ₂ fine-particle bonded body 61 by a mechanism such as hopping conduction, and reach the transparent electrode layer 65 as the anode. Further, the light absorption layer 62 by supplying electrons oxidation state (I ₃ ^-) iodide ions became is reduced from the transparent electrode layer 66 is a cathode receives electrons, the original state ^- Return to (I) .

As can be inferred from the above operating principle, electrons and holes generated in the light absorbing layer 62 can be efficiently separated,
In order to move, the energy level of the electrons in the excited state of the light absorption layer 62 needs to be higher than the conduction band of the anatase-type TiO ₂ fine particles, and the energy level of the holes in the light absorption layer 62 is lower than the redox level. There is a need, Graetz
Since the el-type cell has a lower energy conversion efficiency, a smaller short-circuit current, and a lower open-circuit voltage as compared with the silicon solar cell, improvement has been desired. Further, it is also required to increase the fill factor and durability of the Graetzel type cell.

[0023]

However, in the prior art, since the anatase-type TiO ₂ fine particle conjugate is used as the electron transfer path, the transparent electrode layer and the anatase-type Ti
Electron conduction tended to be scattered at the interface with the bonded O ₂ fine particles and at the interface between the anatase TiO ₂ fine particles. For this reason, the internal resistance generated at the interface between the transparent electrode layer and the anatase-type TiO ₂ fine particle bonded body and at the interface between the anatase-type TiO ₂ fine particles is increased, and as a result, the photoelectric conversion efficiency is reduced.

Further, since the anatase-type TiO ₂ fine particle conjugate has an irregular shape, it takes time for the solution in which the light absorbing layer is dissolved to enter between the anatase-type TiO ₂ fine particles.
Also, it takes time to diffuse ions in the electrolyte. Further, there is a problem that the moving speed of the electrons is not constant.

Therefore, an object of the present invention is to provide a photoelectric conversion device with improved photoelectric conversion efficiency by devising a path for moving charges such as electrons.

Another object of the present invention is to provide a photoelectric conversion device in which electric charges move at a constant speed irrespective of the position of a moving path of electrons.

[0027]

In order to solve the above-mentioned problems, the present invention provides a generating means for generating a charge based on incident light, and one of the generated charges formed in contact with the generating means. And a needle-like semiconductor crystal for moving the needle-like semiconductor crystal to an electrode, wherein the needle-like semiconductor crystal is formed by electrodeposition, A semiconductor crystal is formed.

According to the present invention, there is further provided a generating means for generating an electric charge based on incident light, and formed in contact with the generating means.
A needle-like semiconductor crystal that moves one of the generated charges to an electrode, comprising: forming a granular semiconductor crystal on the needle-like semiconductor crystal; A coating material is formed on the granular semiconductor crystal.

The present invention further provides a step of forming an electrode on a substrate, a step of forming a needle-like semiconductor crystal for transferring charges to the electrode, and a step of forming a needle-like semiconductor crystal on the surface of the needle-like semiconductor crystal based on incident light. Forming a means for generating electric charges, comprising: a step of forming the acicular semiconductor crystal by electrodeposition; and a step of forming a granular semiconductor crystal on the acicular semiconductor crystal. Forming by electro-deposition.

Still further, the present invention provides a method of forming an electrode on a substrate, a step of forming a needle-like semiconductor crystal for transferring electric charges to the electrode, and a step of forming a needle-like semiconductor crystal on the surface of the needle-like semiconductor crystal based on incident light. Forming a generating means for generating an electric charge by a method of manufacturing a photoelectric conversion device, the step of forming a granular semiconductor crystal on the needle-like semiconductor crystal,
Coating the needle-like and granular semiconductor crystals with a coating material.

Further, a solar cell of the present invention is characterized by comprising the above-mentioned photoelectric conversion device, covering means for covering the front and back surfaces of the photoelectric conversion device, and a frame member for fixing the covering means.

[0032]

Embodiments of the present invention will be described below with reference to the drawings.

In the photoelectric conversion device of the present invention, needle-like crystals used for an electron-accepting (n-type) or electron-donating (p-type) charge transfer layer are formed by an electrodeposition method.
The acicular crystal is a so-called whisker, and is composed of an acicular single crystal having no defect or an acicular crystal containing a helical transition or the like.

Further, as shown in FIGS. 1 (a) to 1 (c), the needle-like crystal is formed by growing a large number of needle-like crystals from one point, forming a dendrite, or forming a polygonal line. Including those that have grown.

The needle-shaped crystal includes a cylinder and a cone, a cone having a flat tip, a column having a sharp tip, and a flat tip. In addition, triangular pyramids, quadrangular pyramids, hexagonal pyramids, other polygonal pyramids and those whose tips are flat, and triangular prisms, quadrangular prisms, hexagonal prisms, other polygonal prisms, or triangular prisms with sharp tips, It also includes quadrangular prisms, hexagonal prisms, polygonal prisms other than those, and those having flat ends, and further includes these broken-line structures.

The cross section of the needle-shaped crystal depends on the crystal.
Triangles, quadrangles, hexagons, and other polygons, some of which are almost circular. The sides do not necessarily have to be equal, and may have different lengths. Also,
Needle-like crystals also have an aspect ratio of at least 5 and preferably at least 10 and more preferably at least 100, depending on the light absorption rate.
The above is preferred.

The minimum length passing through the center of gravity of the cross section of the needle-like crystal is also 500 nm or less, preferably 100 nm.
Hereinafter, it is more preferably 50 nm or less. Further, it is preferable to grow the needle-shaped crystal with c-axis orientation in order to improve the crystallinity, in order to improve the electron transfer efficiency. Here, the aspect ratio refers to the ratio of the length to the diameter when the horizontal cut surface of the needle-shaped crystal is a circle or a shape close to a circle, and when the horizontal cut surface of the needle-shaped crystal is a square such as a hexagon. It refers to the ratio of the length to the minimum length passing through the center of gravity of the cut surface.

The needle-like crystal and the mixed crystal preferably have a large energy gap, and more preferably have an energy gap of 3 eV or more. Examples of the electron accepting (n-type) crystal include TiO ₂ , Zn
O, SnO _{2 and the} like are preferable, and examples of the electron donating (p-type) crystal include NiO and CuI.

The mixed crystal is a semiconductor layer in which any one of the charge transfer layers is composed of a mixture of at least two or more different modes or compositions.
More than one kind means a mixed crystal containing needle-like crystals.

FIGS. 2 (a) and 2 (b) are views showing specific examples of the structure of the semiconductor needle crystal and the mixed crystal. Compared to the Graetzel type cell shown in FIG. 11, the effect of the grain boundary is almost eliminated, so that the movement of electrons and holes becomes easier. Further, as shown in FIG. 2B, the semiconductor granular crystal 18 adheres to the semiconductor needle crystal 17, so that the influence of the grain boundary is small and the roughness factor can be improved.

As described later, a coating material 24 made of a material different from that of the mixed crystal is formed on the mixed crystal. Since the diameter of the coating material 24 is smaller than that of the semiconductor granular crystal 18, the roughness factor is further increased, and a dye that easily adheres to the coating material 24 can be used.

Further, even if light is irradiated from any surface of the glass substrate, the irradiated light can reach the light absorbing layer 62 over a wide range. Therefore, the amount of electrons reaching the transparent electrode layer 65 increases.

Hereinafter, in order to explain the effects of the acicular crystal and the mixed crystal thereof, the present embodiment will be described by comparing the present embodiment with a conventional Graetzel type cell.

In the dye-sensitized cells such as the above-described Graetzel type cell, since the light absorption of one dye layer is not sufficient, the surface area is increased to increase the substantial light absorption. The present embodiment is not limited to dye sensitization, and can be widely used in general for photoelectric conversion devices having a structure in which the surface area is increased due to insufficient light absorption. As a method for enlarging the surface, a method of dispersing and joining fine particles like a Graetzel type cell is simple, but there is a problem that the movement of electrons is not sufficiently efficient.

For example, in the above Graetzel type cell, the case where light is incident from the transparent electrode layer 65 side having the anatase type TiO ₂ fine particle bonded body 61 is compared with the case where light is incident from the transparent electrode layer 66 side. The former often has better photoelectric conversion efficiency. This is not only the difference in the amount of light absorbed by the dye, but also the electrons excited by the light absorption move through the anatase-type TiO ₂ fine particle conjugate 61,
This indicates that the probability of reaching the transparent electrode layer 65 decreases as the photoexcitation position moves away from the transparent electrode layer 65. That is, this suggests that a Graetzel type cell having many crystal grain boundaries has not achieved sufficiently efficient electron transfer.

FIG. 3 is a diagram showing a configuration example of the photoelectric conversion device of the present embodiment. In FIG. 3, reference numeral 10 denotes a glass substrate 1
4 and a transparent electrode layer 15, and corresponds to the glass substrate 64 and the transparent electrode layer 65. Reference numeral 11 denotes a semiconductor crystal layer, which is an anatase-type TiO ₂ fine particle bonded body 61.
Is equivalent to Reference numeral 12 denotes a charge transfer layer, which corresponds to the electrolyte 63. Reference numeral 13 denotes a substrate with electrodes, which corresponds to the glass substrate 64 and the transparent electrode layer 66. Between the semiconductor crystal layer 11 and the charge transfer layer 12, there is provided a light absorption layer 16 which is a generating means.

FIGS. 4 (a) and 4 (b) correspond to FIG.
FIG. 2 is an enlarged view of a substrate with electrodes 10 and a semiconductor crystal layer 11 of FIG. FIG. 4C is an enlarged view of the semiconductor granular crystal 18 of FIG. 4B. The semiconductor crystal layer 11 may be formed of only the semiconductor needle-like crystal 17 as shown in FIG.
As shown in FIG. 4B, it may be formed by a semiconductor needle crystal 17 and a semiconductor granular crystal 18, and furthermore, FIG.
As shown in the figure, the semiconductor needle-like crystal 17 and the semiconductor granular crystal 1
8, a coating material 24 may be formed on the surface. here,
The semiconductor needle crystals 17 and the semiconductor granular crystals 18 are made of, for example, zinc oxide, and the coating material 24 is made of, for example, titanium oxide.

The semiconductor granular crystal 18 has a shape different from that of the semiconductor needle-like crystal 17. In particular, when the semiconductor needle-like crystal 18 has a small aspect ratio, when it is formed,
Since the surface area in contact with the charge transfer layer 12 increases, the roughness factor can be increased. The semiconductor granular crystal 18 is formed into particles having a diameter of 50 to 150 nm by electrodeposition or the like in consideration of the transfer efficiency of electrons and the like.

Further, the coating material 24 is formed so that the diameter of the semiconductor granular crystals 18 is 20 nm to 40 nm.

Here, the semiconductor needle-like crystal 17 or the mixed crystal is an n-type wide-gap semiconductor or a p-type wide-gap semiconductor.
In the case where 7 or the mixed crystals 17 and 18 are n-type wide-gap semiconductors, a p-type wide-gap semiconductor, an electrolyte containing a redox pair, a polymer conductor, etc. An electron-donating charge transport layer 12 is required. On the other hand, when the semiconductor needle-like crystal 17 or the mixed crystals 17 and 18 are p-type wide-gap semiconductors, the electron-accepting type charge transport layer 12 is sandwiched between the light absorbing layers 16.
is necessary.

The semiconductor needle crystal layer 17 and the anatase Ti
Compared with the O ₂ fine particle bonded body 61, the probability that electrons or holes generated by photoexcitation in the semiconductor needle-like crystal layer 17 are scattered by grain boundaries before moving to the substrate 10 with electrodes is reduced. In particular, as shown in FIGS. 3 and 4, when one end of all of the semiconductor needle-shaped crystals is configured to be joined to the transparent electrode layer 15, the electrons or electrons are smaller than those of the Graetzel type cell. The effect of grain boundaries is almost completely eliminated when the hole moves.

FIG. 5A is a view showing a state in which light is incident from the semiconductor crystal layer 11 side of the photoelectric conversion device shown in FIG. 3, and FIG. 5B is a view opposite to FIG. 5A. FIG. 3 is a diagram illustrating a state in which light is incident from the charge transfer layer 12 side. FIG. 5 (c)
FIG. 3 is a diagram showing a state in which light is incident from both directions of the semiconductor crystal layer 11 side and the charge transfer layer 12 side. In FIG. 5, the same parts as those in FIG. 1 are denoted by the same reference numerals.

5 (a) to 5 (c), the amounts of incident light reaching the light absorbing layer 16 are shown in FIGS. 5 (c) and 5 (c).
5A, the light absorption layer 16 decreases in the order of FIG.
Irradiation may be performed in any pattern as long as sufficient irradiation light reaches the irradiation light. However, as will be described later, the pattern for irradiating light may be restricted by various circumstances.

Hereinafter, each member shown in FIG. 3 and the like will be described in accordance with the manufacturing process of the photoelectric conversion device.

(Regarding the Substrate with Electrodes) In the photoelectric conversion device, the substrate with electrodes on the light incident side needs to be transparent like the glass substrate 14 or the like. That is, FIG.
In FIG. 5, it is necessary to make the substrate with electrodes 10 transparent.
In (b), the substrate 13 with electrodes needs to be transparent,
In FIG. 5C, the substrates with electrodes 10 and 13 need to be transparent.

The material and thickness of the glass substrate 14 can be appropriately designed according to the durability required for the photoelectric conversion device. As the substrate with an electrode on the light incident side, a glass substrate, a plastic substrate, or the like is suitably used as long as it is translucent.
A metal substrate, a ceramic substrate, or the like can be used as appropriate as a substrate with an electrode that is not the light incident side. It is preferable to provide an antireflection film made of SiO ₂ or the like on the surface of the substrate with electrodes on the light incident side.

(Regarding Electrodes) As shown in FIG. 5, a semiconductor crystal layer 11 and a charge transfer layer 12 are provided between the substrates 10 and 13 with electrodes. Further, as described with reference to FIG. 3, each of the substrates with electrodes 10 and 13 has, for example, a transparent electrode and a glass substrate. The transparent electrode
It is made of indium-tin composite oxide, tin oxide doped with fluorine, or the like.

Although not strictly shown in FIG. 5, the electrode-attached substrate 13 may be provided on the entire surface outside the charge transfer layer 12, or may be provided on a part thereof. For example, the charge transfer layer 1
In the case where 2 is not solid, the transparent electrode layer on the side of the charge transfer layer 12 has
It is preferable that the transparent electrode layer on the side of the charge transfer layer 12 is not provided on the entire surface of the glass substrate of the electrode-attached substrate 13 if the charge transfer layer 12 is solid.

It is preferable to provide a catalyst such as Pt or C on the surface of the transparent electrode layer on the side of the charge transfer layer 12 in order to efficiently reduce the redox couple, for example. Further, when the electric resistance between the light source and the light absorbing layer 16 is sufficiently low, the transparent electrode on the light incident side may be provided with, for example, a finger electrode.

Here, the substrates with electrodes 10 and 13
Has been described as an example in which a transparent electrode layer is provided. However, the electrode of the substrate with an electrode on which light does not enter does not necessarily have to be a transparent electrode layer, and a metal electrode made of Cu, Ag, Al, or the like. Can also be used.

(Regarding Semiconductor Crystal Layer) Next, the semiconductor crystal layer 11 will be described. The semiconductor needle-like crystal 17 can be formed, for example, without using electrodeposition such as CVD or using electrodeposition such as plating. When a needle-like crystal is formed by electrodeposition, the needle-like crystal is grown in a direction parallel to the glass substrate 14 as shown in FIG. It is preferable to grow in a vertical direction, or to grow like a tree as shown in FIG.

It should be noted that the needle-shaped crystal is strictly
It is difficult to grow the crystal in a direction perpendicular to the glass substrate 14.
° or more, more preferably 80 ° or more. Further, it is preferable that the shape of the acicular crystal is linear.

FIG. 7 is an explanatory diagram of a technique for controlling the growth direction of the semiconductor needle-like crystal 17. FIG. 7A shows an example in which an aluminum layer is formed to a thickness of about 0.1 to several μm on a base metal layer 42 provided on a glass substrate 14, and the aluminum layer is anodized to form a nanohole layer 43. 1 shows a state in which a shape crystal is grown.

In FIG. 7B, an aluminum layer provided on the metal electrode 44 is formed to a thickness of about 0.1 to several μm, and the aluminum layer is anodized to form a nanohole layer 43.
And a state in which a needle-like crystal is grown in each nanohole.

The anodic oxidation of the aluminum layer uses oxalic acid, phosphoric acid, sulfuric acid, or the like, and the distance between the nanoholes is controlled by the anodic oxidation voltage. Further, by forming the nanohole layer 43, the diameter of the needle-like crystal can be controlled. To control the diameter of the needle-like crystal, the diameter of each nanohole is controlled by etching with a phosphoric acid solution or the like after anodic oxidation, and the needle-like crystal is grown in each controlled nanohole.

When the nanoholes are formed and then electrolyzed in a plating bath of a needle-like crystal component, the semiconductor needle-like crystals 17 can be grown from the base metal layer 42 or the metal electrode 44 of each nanohole through the nanohole layer 43. . At this time, the electrodeposition conditions are generally important factors in determining the diameter and length of the needle-shaped crystal.

After controlling the diameter, length, and growth direction of the needle-like crystal, the needle-like crystal is immersed in a gel solution or the like using the semiconductor granular crystal 18, as shown in FIGS. 8A and 8B, respectively. Thus, the semiconductor granular crystal 18 is formed on the surface of the semiconductor needle-like crystal 17, and the mixed material is further coated with the coating material 2.
4 can be formed. Thereby, even when the surface area of the acicular crystal is insufficient, the semiconductor granular crystal 18 having a large roughness factor can be produced, and the semiconductor acicular crystal 17 having less influence of the grain boundary on the movement of electrons or holes can be produced. can do.

The semiconductor needle-like crystal layer 17 is mainly manufactured by two methods. One is a manufacturing method by an electrolytic electrodeposition method. The other is a manufacturing method by an electroless electrodeposition method. Each manufacturing method will be described.

FIG. 9 is an explanatory view of a method of manufacturing the semiconductor needle-like crystal layer shown in FIG. 1 by electrolytic electrodeposition. As shown in FIG. 9, a beaker 86 containing an electrolyte 87 is placed on a mantle heater 81. And in the beaker 86,
When the counter electrode 102, the reference electrode 101 and the working electrode 103 are charged and electrolyzed, a needle-like crystal is formed. At this time, the working electrode 1
For the substrate 03, the substrate 10 with electrodes may be used directly, or an insulating part may be formed using a jig or the like, and needle-like crystals may be formed on the substrate 10 with electrodes only in a desired range.

As the electrolytic solution 87, an electrolytic solvent such as acetonitrile, IPA or water can be used. The type of solute of the electrolytic solution 87, the solute concentration, the concentration of active gas such as oxygen in the solution,
The temperature of the electrolytic solution, the presence or absence of a reaction accelerator such as dextrin,
The shape of the acicular crystal can be changed depending on the electrolysis potential value, electrolysis current value, electrolysis time, etc. The needle-shaped crystals may be formed in, for example, a dark room,
The shape can be changed by causing convection of the electrolyte 87 by stirring or the like.

Although it differs somewhat depending on the material of the substrate with electrodes 10 and the like, it is generally preferable to wash the transparent electrode layer 15 and the like in advance using IPA and acetone for surface cleaning. It is important to carry out anodic treatment for dissolving a very small amount.

FIG. 10 shows the semiconductor needle-like crystal 17 shown in FIG.
FIG. 4 is an explanatory view of a manufacturing method by an electroless electrodeposition method. FIG.
As shown in (1), a needle-like crystal is formed by immersing the substrate with electrodes 10 in the electrolytic solution 87 and irradiating the substrate with electrodes 10 with light from the light source 83 through the quartz tube 85. As in the case of the above-mentioned production by the electrolytic electrodeposition method, the shape of the needle crystal can be changed by changing various conditions at the time of forming the needle crystal. Also, when electroless, Pd or Ag is used as a catalyst.
Is effectively attached to the transparent electrode layer 15 or the like.

The semiconductor granular crystal 18 has a diameter of 100 nm by electrodeposition in consideration of the transfer efficiency of electrons and the like.
It is formed so that it is about.

(Regarding Light Absorbing Layer) The light absorbing layer 16 includes
Various semiconductors and dyes can be used. When a semiconductor is used, an i-type amorphous semiconductor having a large light absorption coefficient or a direct transition semiconductor is preferable. When a dye is used, metal complex dye or polymethine dye, perylene dye, rose bengal, eosin Y, mercurochrome, Santalin (Santaiin) dye, cyanine (Cyan)
in) Organic dyes such as dyes and natural dyes are preferred. These dyes preferably have an appropriate bonding group to the surface of the semiconductor fine particles.

Further, preferred binding groups include COOH
Groups, cyano groups, PO ₃ H ₂ groups or chelating groups having π conductivity such as oximes, dioximes, hydroxyquinolines, salicylates and α-keto enolates. Of these, a COOH group and a PO ₃ H ₂ group are particularly preferred. When the dye used in the present embodiment is a metal complex dye,
Ruthenium complex dyes ｛Ru (dcbpy) 2 (SCN) 2, (dcbpy = 2,2-
bipyridine-4,4'-dicarboxylic acid) can be used, but it is important that the oxidized and reduced form is stable.

Also, the potential of the excited electrons in the light absorbing layer,
That is, the potential of the dye that has been photoexcited (LUMO potential of the dye) and the conduction charge potential in the semiconductor are higher than the electron acceptance potential of the electron-accepting charge transport layer (such as the conduction charge potential of an n-type semiconductor), and the photoabsorption layer causes photoexcitation. Is required to be lower than the electron donating potential of the electron donating type charge transfer layer (such as the valence charge potential of the p-type semiconductor and the potential potential of the redox couple). Reducing the recombination probability of excited electrons and holes in the vicinity of the light absorption layer 16 is also important for increasing the photoelectric conversion efficiency.

(Charge Transfer Layer) When an n-type needle crystal is used, it is necessary to form the charge transfer layer 12 so that holes move with the light absorbing layer interposed therebetween. At this time, a redox system can be used for the charge transfer layer 12 as in the case of a wet solar cell. Even when using a redox system,
In addition to a simple solution system, carbon powder may be used as a holding material, or an electrolyte may be gelled. There is also a method using a molten salt or an ion conductive polymer. As a method of further transferring electric charges, an electric field polymerization organic polymer, CuI, C
A p-type semiconductor such as uSCN or NiO can also be used.

On the other hand, when a p-type needle-like crystal is formed, it is necessary to form the charge transfer layer 12 so that electrons move. Therefore, n-type semiconductors such as ZnO and Ti
O ₂ , SnO ₂ or the like can be used as a material.

Since the charge transfer layer 12 in which holes move needs to fill the gap between the semiconductor needle crystals, when the charge transfer layer 12 is formed, the charge transfer layer 12 may be formed by a penetration method that can be used for a liquid or a polymer, or a solid method. Electrodeposition, a CVD method, and the like that can be used for the moving layer are suitable.

In order to efficiently prevent recombination of electrons and holes generated in the dye by light irradiation, electrons need to bond with holes in the light absorbing layer 16 more quickly than in the charge transfer layer 12. It is preferable to use the charge transfer layer 12 in which holes suitable for such conditions move.

(Seal) Although not particularly shown, the photoelectric conversion device of the present embodiment seals at least the space between the substrates 10 and 13 with electrodes, and injects, for example, the charge transfer layer 12 therein. Thus, it is preferable to increase the weather resistance. An adhesive or a resin can be used for the sealing material. When the light incident side is sealed, the sealing material is preferably light-transmitting.

[0082]

Embodiments of the present invention will be described below.

(Embodiment 1) In Embodiment 1 of the present invention, a case where a semiconductor needle crystal 17 is formed by an electrolytic electrodeposition method will be described with reference to FIGS. 3, 4 and 9. First,
A conductive glass substrate (F-doped SnO ₂ , 10Ω / □) was prepared as the substrate 10 with electrodes, and this substrate was
03, for example, 8
0.01 m which is the electrolyte 87 heated to 5 ° C.
ol / L zinc nitrate aqueous solution, and the conductive glass substrate
A potential of 1.6 V was applied for 10,000 seconds.

Subsequently, 0.1 mol heated to 60 ° C.
The substrate is immersed in 1 / L zinc nitrate IPA solution, for example,
A voltage of 5.0 V was applied for 100 seconds. Thereafter, the substrate was placed in a tubular electric furnace, and oxygen was added to 1.67 × 10 ⁻³ L.
For example, a heat treatment was performed at 500 ° C. for 1 hour while flowing / S.

As a result, the needle-like ZnO crystal, which is the semiconductor needle-like crystal 17, was formed on the surface of the conductive glass substrate in FIG.
As shown in the figure, the growth was perpendicular to the conductive glass substrate. The diameter of the semiconductor needle crystal 17 is 100 to 200.
nm, and the aspect ratio was 50-100.

The semiconductor granular crystals 18 were electrodeposited on the surface of the semiconductor needle crystals 17. Semiconductor granular crystal 1
The diameter of 8 was 20 to 40 nm.

A dye was used for the light absorbing layer 16.
Specifically, Ru is a Ru complex reported by Graetzel et al.
((bipy) (COOH) ₂ ) ₂ (SCN) ₂ was used. The dye is dissolved in distilled ethanol, and the conductive glass substrate on which the ZnO needle crystals are formed is immersed in the ethanol for 24 hours, for example, so that the dye is adsorbed on the ZnO needle crystals. It was dried at a temperature of about 80 ° C.

The charge transfer layer 12 is formed of I ⁻ / I ₃ ⁻
Redox couples were used. Solute is tetrapropylammonium iodide
(0.46 mol / L) and iodine (0.06 mol / L)
L) and the solvent is ethylene carbonate (ethylene
carbonate) (80 vol%) and acetonitrile (acet)
onitrile) (20 vol%). This mixed solution was dropped on a conductive glass substrate on which ZnO needle-like crystals were formed, and then a substrate 13 with electrodes was attached to form a cell. As the electrode-attached substrate 13, a conductive glass substrate formed by sputtering platinum with a thickness of 1 nm was used.

As a comparative example, a paste in which ZnO powder having a particle diameter of 100 nm as a main component was dispersed was applied on a conductive glass substrate and baked at 500 ° C. for 30 minutes to form a ZnO film. A cell was prepared in the same manner as described above. Then, xenon lamp light of 500 W equipped with an ultraviolet cut filter was irradiated from the substrate 13 side with the electrode. Then, the value of the photocurrent due to the photoelectric conversion reaction generated at this time was measured.

As a result of the measurement, the open potential and the fill factor of the cell of this example were improved by about 7%. This is considered to be because the internal resistance of the electron-accepting type charge transfer layer was reduced by using the needle-like crystals.

Embodiment 2 In Embodiment 2 of the present invention, a semiconductor-containing crystal 17 and a semiconductor granular crystal 18 are grown by electrolytic electrodeposition, a solution containing titanium is applied, and the substrate is heat-treated. The case where the coating material 24 is formed on the mixed crystal will be described with reference to FIGS. 3, 4, and 9.

First, a conductive glass substrate (F-doped SnO ₂ , 10Ω / □) was prepared as the substrate 10 with electrodes.
This substrate is used as the working electrode 103 and the mantle heater 81
Immersed in an aqueous solution of 0.001 mol / L zinc chloride, which is an electrolysis 87 heated to, for example, 85 ° C.
Applied for 0 seconds.

Subsequently, 0.1 mol heated to 60 ° C.
The substrate was immersed in 1 / L zinc nitrate IPA solution, and
Was applied for 100 seconds. Thereafter, the substrate was placed in a tubular electric furnace, and a heat treatment was performed at, for example, 500 ° C. for 1 hour while flowing oxygen at 1.67 × 10 ⁻³ L / S.

As a result, similarly to Example 1, the semiconductor needle-like crystals 17 were grown on the surface of the conductive glass substrate in the direction perpendicular to the conductive glass substrate. Further, the semiconductor granular crystals 18 were electrodeposited on the surface of the semiconductor needle crystals 17. The diameter of the semiconductor needle-like crystal 17 was 50 to 150 nm, and the aspect ratio was 50 to 100. The diameter of the semiconductor granular crystal 18 was 20 to 40 nm.

Thereafter, the substrate was immersed in a 0.1 mol / L aqueous solution of titanium tetrachloride. Subsequently, it was placed in a tubular electric furnace and 500 ° C. while flowing oxygen at 1.67 × 10 ⁻³ L / S.
For 30 minutes. As a result, the mixed crystal was coated with the coating material 24 made of titanium oxide.

Further, a dye was used for the light absorbing layer 16.
Specifically, Ru is a Ru complex reported by Graetzel et al.
((bipy) (COOH) ₂ ) ₂ (SCN) ₂ was used. The dye is dissolved in distilled ethanol, and a substrate coated with the semiconductor needle crystals 17 and the semiconductor granular crystals 18 by the coating material 24 is immersed therein for, for example, 24 hours to adsorb the dye onto the semiconductor needle crystals 17 and the like. And taken out from the electrolyte 87 and dried at a temperature of about 80 ° C.

Further, conductive glass (F-doped SnO)_Two,
10 Ω / □) on platinum
The redox pair is I^-
/ I_Three ^-Was used. The solute is 0.05 mol / L I_Two(You
Element) and 0.1 mol / L LiI (lithium iodide)
0.6 mol / L DMPI (Im) (1,2-dimethyl-3-
Propyl imidazolium iodide) and 0.5mo
1 / L TBP (4-tert-butylpyridine), solvent is MA
Using N (MeOAN) (methoxyacetonitrile)
Was. A conductive glass substrate on which a mixed crystal is formed by mixing this mixed liquid
And the substrate 13 with electrodes is attached to the cell.
It was created.

Further, as a comparative example, a cell in which a paste in which ZnO powder having a particle diameter of 100 nm as a main component was dispersed was applied on conductive glass and baked at 500 ° C. for 30 minutes was similarly assembled. . Then, in the same manner as in Example 1, a 500 W xenon lamp light with an ultraviolet cut filter was applied from the counter electrode side, and the value of the photocurrent due to the photoelectric conversion reaction generated at this time was measured. As a result of the measurement, both the open potential and the fill factor of the cell of the present invention were increased.

(Embodiment 3) In Embodiment 3 of the present invention, a case where a semiconductor needle-like crystal layer is formed from nanoholes by an electrolytic electrodeposition method will be described with reference to FIGS. First, a conductive glass substrate (F-doped SnO ₂ , 10Ω / □) was prepared as the glass substrate 41 and the base electrode layer 42, and Al was deposited on the surface of the substrate, for example, to a thickness of 0.5 μm.
After the Al layer was anodized at 40 V in 0.3 mol / L of oxalic acid, phosphoric acid of 5 wt. % For 40 minutes.
In the nanohole layer 43 anodized by this process,
Many nanoholes having a diameter of about 50 nm were formed at intervals of about 100 nm.

Next, this substrate is used as a working electrode 103 and immersed in an aqueous solution of 5 mmol / L zinc chloride and 0.1 mol / L potassium chloride, which is an electrolyte 87 heated to, for example, 85 ° C. by a mantle heater 81. A potential of -0.9 V was applied to the conductive glass substrate for 5000 seconds.

Subsequently, 0.1 mol heated to 60 ° C.
The substrate is immersed in 1 / L zinc nitrate IPA solution, for example,
A voltage of 5.0 V was applied for 100 seconds. Thereafter, the substrate was placed in a tubular electric furnace, and oxygen was added to 1.67 × 10 ⁻³ L.
For example, a heat treatment was performed at 500 ° C. for 1 hour while flowing / S.

As a result, as shown in FIGS. 7 (a) and 7 (b), on the surface of the conductive glass substrate, a ZnO needle-like crystal, which is a semiconductor needle-like crystal 17 from nanoholes, is formed. Growth in the vertical direction. ZnO
The diameter of the acicular crystal is 30 to 50 nm, and the length is 30
６０60 times.

On the surface of the semiconductor needle-like crystal 17, a semiconductor granular crystal 18 was electrodeposited. Semiconductor needle crystal 1
7 has a diameter of 100 to 200 nm and an aspect ratio of 5
It was 0-100. The diameter of the semiconductor granular crystal 18 was 20 to 40 nm.

A dye was used for the light absorbing layer 16.
As the dye, commercially available eosin Y was used. The dye is dissolved in distilled ethanol, and the conductive glass substrate on which the ZnO needle crystals are formed is immersed therein for, for example, 24 hours, and the dye is adsorbed on the ZnO needle crystals.
It was dried at a temperature of about 80 ° C.

The charge transfer layer 12 is formed of I ⁻ / I ₃ ⁻
Redox couples were used. Solute is 0.05mol / L
I ₂ (iodine), 0.1 mol / L Lil (lithium iodide), 0.6 mol / L DMPI (Im) (1,2-dimethyl-3-propylimidazolium iodide) and 0.5 mol / L TBP (4 -tert-butylpyridine). MAN (MeOAN) (methoxyacetonitrile) was used as the solvent. This mixed solution was dropped on a conductive glass substrate on which ZnO needle-like crystals were formed, and then a substrate 13 with electrodes was attached to form a cell. As the electrode-attached substrate 13, a conductive glass substrate formed by sputtering platinum with a thickness of 1 nm was used.

As a comparative example, a paste in which ZnO powder having a particle diameter of 100 nm as a main component was dispersed was applied on a conductive glass substrate and baked at 500 ° C. for 30 minutes to form a ZnO film. In other manufacturing steps, cells were prepared in the same manner as described above. In the same manner as in Example 1, a 500 W xenon lamp with a UV cut filter was applied from the side of the substrate 13 with electrodes. Then, the value of the photocurrent due to the photoelectric conversion reaction generated at this time was measured.

As a result of the measurement, the open-circuit potential and the fill factor of the cell of this example were improved by about 5%. This is considered to be because the internal resistance of the electron-accepting type charge transfer layer was reduced by using the needle-like crystals.

(Embodiment 4) In Embodiment 4 of the present invention, a case where a semiconductor needle crystal layer is grown by electrolytic electrodeposition and a semiconductor crystal is formed thereon will be described with reference to FIGS. . Pt as a base electrode layer 42 on a glass substrate 41
Was formed to a thickness of about 1 μm. Next, the base electrode layer 42
The glass substrate 41 on which is formed as a working electrode 103 is immersed in a 0.01 mol / L zinc nitrate DMF (dimethyl sulfoxide) solution which is an electrolyte 87 heated to, for example, 85 ° C. by a mantle heater 81, −
A potential of 1.0 V was applied for 10,000 seconds. Then,
IPA of 0.1 mol / L zinc nitrate heated to 60 ° C
The substrate is immersed in the solution, and for example, a voltage of
For 2 seconds. Thereafter, the substrate was placed in a tubular electric furnace, and a heat treatment was performed at, for example, 500 ° C. for 1 hour while flowing oxygen at 1.67 × 10 ⁻³ L / S.

Thereafter, on the surface of the base electrode layer 42, a ZnO needle crystal, which is the semiconductor needle crystal 17, is formed as shown in FIG.
It grew as shown in FIG. The diameter of the acicular ZnO crystal was 40 to 70 nm, and the length was 20 to 200 times the length.

On the surface of the semiconductor needle-like crystal 17, a semiconductor granular crystal 18 was electrodeposited. Semiconductor needle crystal 1
7 has a diameter of 100 to 200 nm and an aspect ratio of 5
It was 0-100. The diameter of the semiconductor granular crystal 18 was 20 to 40 nm.

Further, a glass substrate 41 on which ZnO needle-like crystals were formed was prepared by adding 3 g of anatase-type TiO ₂ microcrystals (P25) having a particle size of about 20 nm to 40 mL of water and 0.1 mL of acetylacetone.
2 mL and 0.2 mL of Triton-X (registered trademark: Union Carbide Co., Ltd.) were immersed in a slurry solution, and further 450 ° C. while flowing oxygen at 1.67 × 10 ⁻³ L / s. For 1 hour to form semiconductor granular crystals 18 on ZnO needle crystals.

Further, a dye was used for the light absorbing layer 16.
Commercially available mercurochrome was used as the dye. The dye is dissolved in distilled ethanol, into which semiconductor granular crystals 18, Z
The glass substrate 41 on which the nO needle-shaped crystals are formed is
After immersion for a time, the dye is Z
After being adsorbed on the nO needle crystal, it is taken out of the solution,
It was dried at a temperature of about 80 ° C.

As the substrate with electrodes, a conductive glass (F-doped SnO ₂ , 10 Ω / □) formed with graphite to a thickness of about 1 nm is used, and the charge transfer layer 12 is made of CuI which is a p-type semiconductor. used.

CuI is dissolved in anhydrous acetonitrile, and a dye-supported needle-like ZnO crystal and anatase Ti
It was deposited at the film interface of the mixed crystal of O ₂ microcrystals. In this way, the photoelectric conversion device was prepared by superposing the solid charge transfer layer 12 on the glass substrate 41 and the electrode-provided substrate disposed opposite the electrode.

Further, as a comparative example, a ZnO powder having a particle size of about 30 nm as a main component was heat-treated to form a needle-like ZnO crystal. . In the same manner as in Example 1, a 500 W xenon lamp with a UV cut filter was applied from the substrate with electrodes. Then, the value of the photocurrent due to the photoelectric conversion reaction generated at this time was measured.

As a result of the measurement, the open-circuit potential and the fill factor of the cell of this example were improved by about 9%. This is considered to be because the internal resistance of the electron-accepting type charge transfer layer was reduced by using the needle-like crystals.

(Embodiment 5) In Embodiment 5 of the present invention, a case where a semiconductor needle-like crystal layer is formed by an electroless electrodeposition method will be described with reference to FIGS. First, a conductive glass substrate (F-doped SnO
₂ , 10 Ω / □), and Sd is applied as a surface treatment on this substrate in order to attach Pd as a catalyst to the transparent electrode layer 15.
1 (made by Kojundo Chemical Co., Ltd.) for about 3 minutes, and then immersion in P-1 (made by Kojundo Chemical Co., Ltd.) for about 1 minute
Repeated times.

Next, this substrate was immersed in an aqueous solution of a mixture of 0.01 mol / L zinc nitrate and 0.1 mol / L dimethylamine borane, which is an electrolyte 87, and a conductive glass substrate was Fixed. 85 of electrolyte 87
Heating was performed by a mantle heater 81 to a temperature of about ° C., and light was irradiated from above from a xenon lamp, which is a light source 83, to perform electrodeposition for about one hour. As a result,
On a conductive glass substrate, Zn as a semiconductor needle-like crystal 17 was formed.
O-needle crystals formed. The diameter of this crystal is 50-80n
m, and the length was 10 to 20 times the length.

Thereafter, in order to form the semiconductor granular crystals 18 into ZnO needle-like crystals, the substrate is permeated into a 0.1 mol / L aqueous solution of titanium tetrachloride, and oxygen is further added to 1.67 × 1.
The baking was performed at 500 ° C. for 30 minutes while flowing at 0 ⁻³ L / s.

As the dye serving as the light absorbing layer 16, commercially available eosin Y was used. Dissolve the dye in distilled ethanol,
The ZnO electrode was immersed therein for 24 hours to adsorb the dye onto the ZnO needle crystals on which the semiconductor granular crystals 18 were formed, and then taken out of a 0.1 mol / L aqueous solution of titanium tetrachloride and dried at 80 ° C. In addition, a substrate 13 with electrodes in which platinum was formed by sputtering to a thickness of 1 nm on conductive glass was used, and the redox pair used was I ⁻ / I ₃ ⁻ . Solute is 0.0
5 mol / L I ₂ (iodine) and 0.1 mol / L LiI
(Lithium iodide) and 0.6 mol / L DMPI (I
m) (1,2-Dimethyl-3-propylimidazolium iodide), 0.5 mol / L TBP (4-tert-butylpyridine), and MAN (MeOAN) (methoxyacetonitrile) as a solvent. This mixed solution was dropped on conductive glass with ZnO, and sandwiched between substrates 13 with electrodes to manufacture a photoelectric conversion device.

As a comparative example, a cell was similarly assembled using a heat-treated ZnO powder having a particle diameter of 100 nm as a main component. In the same manner as in Example 1, a 500 W xenon lamp with a UV cut filter was applied from the counter electrode side. Then, the value of the photocurrent due to the photoelectric conversion reaction generated at this time was measured. As a result of the measurement, the open-circuit potential and the fill factor of the cell of this embodiment were about 7% higher. This is considered to be because the internal resistance of the electron-accepting type charge transfer layer was reduced by using the needle-like crystals.

As described above, in the embodiments and examples of the present invention,
Although the photoelectric conversion device has been described as an example, for example, a solar cell may be formed by providing the photoelectric conversion device with a covering unit such as a sheet or glass covering the front and back surfaces and a frame material for fixing the covering unit. Good.

[0123]

As described above, in the photoelectric conversion device of the present invention, a needle-like semiconductor crystal for transferring one of the charges generated based on the incident light to the electrode is formed by electrodeposition. Conversion efficiency can be improved.

Further, in the photoelectric conversion device of the present invention, since the shape of the semiconductor crystal is needle-shaped as described above, the charge can be moved at a constant speed regardless of the position of the electron movement path, or the photoelectric conversion device can be used. Open circuit voltage can be increased.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of the definition of a needle crystal.

FIG. 2 is a diagram showing a specific configuration example of a semiconductor needle crystal and a mixed crystal.

FIG. 3 is a diagram illustrating a configuration example of a photoelectric conversion device according to an embodiment of the present invention.

FIG. 4 is an enlarged view of the photoelectric conversion device of FIG.

FIG. 5 is a diagram showing how light is incident on the photoelectric conversion device of FIG. 3;

FIG. 6 is an enlarged view of a semiconductor crystal for transferring charges.

FIG. 7 is an explanatory diagram of a technique for controlling a growth direction of a needle crystal.

FIG. 8 is a diagram showing a state in which a granular semiconductor crystal is formed on the surface of a semiconductor needle crystal.

9 is an explanatory view of a method for producing the semiconductor needle-like crystal layer shown in FIG. 1 by an electrolytic electrodeposition method.

10 is an explanatory diagram of a method for producing the semiconductor needle-like crystal shown in FIG. 1 by an electroless electrodeposition method.

FIG. 11 is a configuration diagram of a conventional photochemical cell.

[Explanation of symbols]

10, 13 Substrate with electrode 11 Semiconductor crystal layer 12 Charge transfer layer 14, 41, 64 Glass substrate 15, 65, 66 Transparent electrode layer 16, 62 Light absorbing layer 17 Semiconductor needle crystal 18 Semiconductor granular crystal 42 Base electrode layer 43 Nanohole Layer 44 Metal electrode 61 Anatase-type TiO ₂ fine particle bonded body 63 Electrolyte 81 Mantle heater 82 Fixed base 83 Light source 85 Quartz tube 86 Beaker 87 Electrolyte 101 Reference electrode 102 Counter electrode 103 Working electrode

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toru Tada 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 5F051 AA14 5H032 AA06 AS16 BB07 BB10 CC11 CC16 EE02 EE16 HH04

Claims (19)

[Claims] 1. A photoelectric conversion device comprising: generating means for generating electric charges based on incident light; and a needle-shaped semiconductor crystal formed in contact with the generating means and moving one of the generated electric charges to an electrode. An apparatus, wherein the needle-shaped semiconductor crystal is formed by electrodeposition,
Further, a granular semiconductor crystal is formed on the acicular semiconductor crystal by electrodeposition. 2. A photoelectric conversion device comprising: a generating means for generating an electric charge based on incident light; and a needle-like semiconductor crystal formed in contact with the generating means and moving one of the generated electric charges to an electrode. An apparatus, wherein a granular semiconductor crystal is formed on the acicular semiconductor crystal,
Further, a photoelectric conversion device for forming a coating material on the acicular and granular semiconductor crystals. 3. The photoelectric conversion device according to claim 2, wherein said needle-like semiconductor crystal is formed by electrodeposition. 4. The needle-like semiconductor crystal according to claim 1, wherein the minimum length passing through the center of gravity of the cross-section is 1 μm or less and the aspect ratio is 10 or more. 2. The photoelectric conversion device according to claim 1. 5. The photoelectric conversion device according to claim 1, wherein the needle-like semiconductor crystal is formed in a direction perpendicular to the electrode. 6. The photoelectric conversion device according to claim 1, wherein the needle-like semiconductor crystal is zinc oxide. 7. The granular semiconductor crystal has a diameter of 100 to prevent one of the charges from moving to the electrode.
The photoelectric conversion device according to any one of claims 1 to 6, wherein the particles are particles having a size of nm or less. 8. The photoelectric conversion device according to claim 1, wherein the granular semiconductor crystal exists on a surface of the needle-like semiconductor crystal. 9. The photoelectric conversion device according to claim 1, wherein said generation means is constituted by a dye. 10. The photoelectric conversion device according to claim 1, wherein the granular semiconductor crystal is a metal oxide. 11. The photoelectric conversion device according to claim 1, wherein the granular semiconductor crystal is zinc oxide. 12. The semiconductor device according to claim 1, wherein said granular semiconductor crystal is titanium oxide.
Item 6. The photoelectric conversion device according to Item 1. 13. The photoelectric conversion device according to claim 1, wherein the granular semiconductor crystal is tin oxide. 14. The photoelectric conversion device according to claim 1, wherein the coating material is titanium oxide. 15. The photoelectric conversion device according to claim 1, wherein a layer having nanoholes is formed on the electrode, and the needle-like semiconductor crystal is formed on the nanoholes. 16. The photoelectric conversion device according to claim 1, wherein the acicular semiconductor crystal is c-axis oriented. 17. A step of forming an electrode on a substrate; a step of forming a needle-like semiconductor crystal for transferring charges to the electrode; and generating charges on the surface of the needle-like semiconductor crystal based on incident light. Forming a generating means, comprising: a step of forming the acicular semiconductor crystal by electrodeposition; and a step of forming a granular semiconductor crystal on the acicular semiconductor crystal by electrodeposition. Forming a photoelectric conversion device. 18. A step of forming an electrode on a substrate; a step of forming a needle-shaped semiconductor crystal for transferring charges to the electrode; and generating charges based on incident light on a surface of the needle-shaped semiconductor crystal. Forming a granular semiconductor crystal on the acicular semiconductor crystal, and coating the acicular and granular semiconductor crystal with a coating material. And a method for manufacturing a photoelectric conversion device. 19. A photoelectric conversion device comprising: the photoelectric conversion device according to any one of claims 1 to 16; a covering unit that covers a front surface and a back surface of the photoelectric conversion device; and a frame member that fixes the covering unit. Features solar cells.