JP2003258278A - Photoelectric conversion device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxide photoelectric conversion element which has satisfactory open circuit voltage and current in a simple and inexpensive method. <P>SOLUTION: This photoelectric conversion device is formed by laminating an n-type layer composed of a ZnO needle crystal 13 and a p-type layer composed of a Cu<SB>2</SB>O layer 14. The ZnO needle crystal 13 is connected to the continuous film of an n-type oxide semiconductor layer 31 composed of ZnO or SnO<SB>2</SB>. The average diameter of the ZnO needle crystal 13 is set to be 300 nm or less, and the aspect ratio is set to be 20 or more. <P>COPYRIGHT: (C)2003,JPO

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 and a manufacturing method thereof, and more particularly to a photoelectric conversion device in which both an n-type layer and a p-type layer are made of an oxide material and a manufacturing method thereof. In particular, the present invention can be applied to low-cost solar cells.

[0002]

2. Description of the Related Art Conventionally, a solar cell using a semiconductor junction such as silicon or gallium-arsenic has been generally used as a method for converting light energy into electric energy. Among them, single crystal silicon solar cells and polycrystalline silicon solar cells using pn junctions of semiconductors, and amorphous silicon solar cells using pin junctions are well known and are being put to practical use.

However, since a silicon solar cell is expensive to manufacture and consumes a lot of energy in the manufacturing itself,
Long-term use is required to recover the installation cost and energy consumption. It is this cost that is the main bottleneck of current diffusion.

On the other hand, in recent years, researches for practical use of CdTe, CuIn (Ga) Se and the like as second generation thin film solar cells have been progressing, but environmental problems and resource problems have been raised in these material systems. .

As a photoelectric conversion element using ZnO or Cu ₂ O, a pin type structure is disclosed in Japanese Patent Laid-Open No. 2001-53329. In this pin type, the i layer is TiO ₂ ,
The p layer has a laminated film structure of cuprous oxide, copper oxide, nickel oxide, and the n layer has tin oxide, indium oxide, ZnO, and zinc sulfide. Further, a photoelectric conversion element in which ZnO and Cu ₂ O are laminated and sputtered is shown in Sol. Energy Mat. 4, 101 (1980), but the conversion efficiency is about 0.2%.

The most general type of photoelectric conversion element using Cu ₂ O is a Schottky junction type photoelectric conversion element.
It is summarized in lid-State Electronics Vol.29, PP7-17 (1986).

Here, Cu ₂ O will be briefly described. Cu ₂ O is a p-type semiconductor, and various studies have been made for a long time. This Cu ₂ O was generally used for rectifiers, photocells, red pigments, ship bottom paints, etc., but nowadays, different materials are mainly used for different purposes.

However, since it is inexpensive and has no harmful properties, it is a material that is constantly being researched for new utilization methods. As a method for producing them, there is a method of adding a copper sulfate solution to a tin (II) chloride solution made alkaline with potassium hydroxide to cause precipitation.

However, it is difficult to obtain a stable p-type semiconductor by this method. Although it can be manufactured by using a PVD method such as a sputtering method, there are many problems in terms of cost and environment. However, the electrodeposition method has recently attracted attention as a method capable of forming Cu ₂ O having a bandgap of about 2 eV in a large area and manufacturing it at a low cost.

For example, by applying a potential in an aqueous solution in which CuSO ₄ , lactic acid and sodium hydroxide are mixed,
A method of depositing Cu ₂ O on an electrode has been reported by Jay A. Switzer et al. (Chem. Mater. 1996, 8, 2499).
In addition, Yongsug Tak et al. Reported that Cu ₂ O electrodeposition under acidic conditions was film-formed using a Cu (NO ₃ ) ₂ aqueous solution (Electrochemical and Solid-State Letters, 2 (1
1) 559 (1999)).

Next, the ZnO thin film and the ZnO needle crystal will be described. Generally, various means such as a sputtering method, a vapor deposition method, a CVD method, and an electrodeposition method can be currently used as a means for producing a ZnO film.

In particular, the electrodeposition method has been attracting attention as a manufacturing method for the purpose of increasing the area and reducing the cost. For example, it has been reported that a ZnO film is uniformly formed on a conductive substrate (Appl. Phys. Lett., Vol.68, No.17, 1996 243).
9, J. Electrochem. Soc., 146, 4517 (1999), JP-A-8-217443 and JP-A-8-260175).

[0013] As a means for producing ZnO needle-shaped crystals, "J. Crystal Growth, 102, 965, (1990)" describes tetrapod-like needle-shaped ZnO crystals by vapor phase oxidation of metallic Zn. It has been reported that it was manufactured at ℃.

Furthermore, "Jpn.J.Appl.Phys., Vol.38 (1999)
pp.L586 ", diameter 1.5 by using open-air CVD method
It has been reported that ZnO needle-shaped crystals having a length of 100 μm can be produced in μm. In a film forming method such as CVD or sputtering, a ZnO film has to be formed on a substrate under a vacuum condition or a condition in which a high-purity gas such as argon gas is sealed and maintained at a high temperature or the like. Therefore, the area of the substrate is limited and the cost is high.

In contrast to these film forming methods, the electrodeposition method performs electrodeposition in an electrolytic solution, so there is no need to evacuate or maintain at a high temperature, so that the cost is reduced and the area of the substrate is increased. Is also possible.

[0016]

However, in the conventional technique, the oxide photoelectric conversion element was not able to obtain a sufficient open circuit voltage or current value. Further, the film forming apparatus and film forming process for ZnO and Cu ₂ O are also costly.
In particular, Cu ₂ O film formation is troublesome because it requires film formation in a special atmosphere and quenching (quenching) from a high temperature.

Therefore, the present invention is to provide an element having a high photoelectric conversion efficiency such as an open-circuit potential and a short-circuit current value. It is an object to provide an oxide photoelectric conversion element having particularly high stability.

Another object of the present invention is to easily and inexpensively obtain an oxide photoelectric conversion element with a sufficient open circuit voltage and current value.

[0019]

In order to solve the above-mentioned problems, the present invention provides a photoelectric conversion device in which an n-type layer and a p-type layer are laminated, wherein the n-type layer is made of ZnO acicular crystals. The photoelectric conversion device is characterized in that the p-type layer is a layer made of Cu ₂ O.

Here, the ZnO needle crystal layer is formed of ZnO or Sn.
It is preferably connected to a continuous film of an n-type oxide semiconductor made of O ₂ . Further, it is preferable that the ZnO acicular crystals have an average diameter of 300 nm or less and an aspect ratio of 20 or more.

Further, the present invention provides a method for manufacturing a photoelectric conversion element having the above structure. That is, it is a method for manufacturing a photoelectric conversion device in which an n-type layer and a p-type layer are stacked and formed,
The n-type layer is a layer made of ZnO needle crystals, the p-type layer is a layer made of Cu ₂ O, and the Cu ₂ O is
A method for manufacturing a photoelectric conversion device, which comprises a step of growing a layer made of a metal by plating.

Here, it is preferable to have a step of growing a layer made of ZnO needle crystals by plating. Particularly, it is preferable to grow the Cu ₂ O layer by plating after the step of growing the ZnO needle crystal layer by plating. Further, it is preferable to have a step of heat-treating the Cu ₂ O layer at a temperature of 500 ° C. or lower after the step of growing the Cu ₂ O layer by plating.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

<Outline of the Present Invention> In the photoelectric conversion device of the present invention, light is mainly absorbed by Cu ₂ O, and electrons and holes generated there are rapidly separated to reduce recombination as much as possible. To reach. Specifically, the p-layer and the n-layer are joined in a structure in which the size is equal to or less than a micrometer and are regularly intricate, and among the holes and electrons generated by light absorption in Cu ₂ O, which is the p-layer, the electron is By rapidly moving the junction layer in the vicinity to the acicular ZnO layer, which is the n-layer, recombination, which lowers the conversion efficiency, is efficiently prevented.

Further, the photoelectric conversion element is formed by a plating method.

<Structure of Photoelectric Conversion Device> First, the structure of the photoelectric conversion device of this embodiment will be described.

FIG. 1A and FIG. 1B are schematic configuration diagrams of the photoelectric conversion device according to the embodiment of the present invention. In FIG. 1, 11 is a substrate, 12 and 17 are transparent electrodes, and 13 is Z.
nO needle crystals, 14 is a Cu ₂ O layer, and 15 and 16 are electrodes. Although not shown, a lead electrode is provided for the purpose of characteristic evaluation in addition to this.

The overall structure greatly differs depending on which side the light is incident on.

In FIG. 1A, the transparent electrode 12 is provided on the substrate 11 side.
And an electrode 15 is provided on the opposite side. Light is incident from the substrate 11 side.

FIG. 1B shows an example in which an electrode 16 is provided on the substrate 11 side and a transparent electrode 17 is provided on the opposite side. Light is incident from the opposite side of the substrate 11.

Although not shown in FIG. 1, both electrodes may be transparent electrodes so that light irradiation can be performed from either surface.

FIG. 3 is a diagram showing a state in which an n-type oxide semiconductor layer 31 is added to the photoelectric conversion device shown in FIG. 1 (a).
The photoelectric conversion device shown in FIG. 3 includes an n-type oxide semiconductor layer 31 between the ZnO needle crystal 13 and the transparent electrode 12, and
This is preferable in that the O needle crystal 13 can be easily formed and the leak current due to a pinhole or the like is reduced.

<ZnO Needle Crystals> The ZnO needle crystals 13 may have a thin tip as shown in FIGS. 1 (a) and 1 (b), but may be the ones shown below.

2 (a) and 2 (b) are shown in FIG. 1 (a),
It is sectional drawing which shows various examples of the ZnO needle crystal 13 of FIG.1 (b). FIG. 2 (a) shows a crystal having a relatively uniform diameter, and FIG. 2 (b) shows a crystal that is curved or branched in the middle. It should be noted that the transparent electrode 12 and the electrode 16 are not shown here for convenience of description.

The tip of the ZnO needle crystal 13 may be sharp or flat. The cross section of the ZnO needle crystal 13 is generally hexagonal,
Other than that may be used. In addition, the aspect ratio means the ratio of the length to the diameter when the lateral cross section of the ZnO needle crystal 13 has a circular shape or a shape close to a circle,
When the lateral cross section of the ZnO needle crystal 13 is a polygon such as a hexagon, the ratio of the length to the minimum length passing through the center of gravity of the cut surface is referred to.

In the present embodiment, ZnO needle crystals 13 having an average diameter of 300 nm or less and an aspect ratio of 20 or more are preferable in terms of photoelectric conversion characteristics. In addition, ZnO needle crystals 13
The angle formed by the axial direction and the main surface of the substrate is preferably 60 ° or more, and more preferably 80 ° or more.

There are various methods for producing such ZnO needle crystals 13, but the plating method is excellent as a method that can be manufactured at a low substrate temperature and at low cost. Also, by adopting the plating method, C
It is possible to plate u ₂ O.

Next, a method for producing the ZnO needle crystals 13 by electrodeposition will be described. The ZnO needle-like crystal 13 can be prepared by electrodeposition by using a three-electrode or two-electrode method, immersing the electrode substrate in an electrolyte solution containing at least zinc ions, and applying a potential. You can

Examples of the compound usable as the salt containing zinc include zinc nitrate, zinc chloride, zinc sulfate, zinc carbonate, zinc acetate and the like. As the electrolyte, one kind of compound selected from these compounds or a mixture of two or more kinds can be used.

As a condition for forming the ZnO needle-like crystals 13, a low concentration is preferred to obtain a high aspect ratio,
A range of about 1 mmol / L to 0.05 mol / L is suitable, and a range of about 1 mmol / L to 0.01 mol / L is more preferable.

As the electrolytic solvent, an organic medium such as ethanol, water, water in which a gas such as oxygen is dissolved, or the like is used, but water is preferable from the viewpoint of easy handling.

FIG. 5 is a schematic configuration diagram of an apparatus for producing the ZnO acicular crystals 13 of FIG. Here, a manufacturing apparatus for performing electrodeposition with three electrodes is shown. Reference electrode 51, counter electrode 52,
By dipping the working electrode 53 in the electrolyte solution 55 in the beaker 54 and applying a potential, the substrate 11 serving as the working electrode 53 is Z
The nO needle crystal 13 grows.

As the preparation conditions, an electrolyte containing at least a zinc salt and its electrolyte concentration, an electrolytic solvent such as IPA or water, an electrolytic potential value, a temperature of the electrolytic solution, an electrodeposition time, an active gas concentration such as oxygen, electrolysis, etc. In addition to optimizing the convection conditions of the liquid, it is also effective to add an additive.

For example, when performing electrodeposition using zinc nitrate, the zinc nitrate concentration is 1 mmol / L to 0.1 mol / L.
Is preferred, and the electrolytic potential of the working electrode of Ag / AgCl with respect to the reference electrode 51 is preferably -0.9V to -1.5V.

When water is used as the electrolytic solution, the temperature of the electrolytic solution is 85 ° C. to 90 ° C. by using the mantle heater 56.
ZnO needle-shaped binding with a large aspect by controlling the temperature to 1 ℃
Crystal 3 grows. Further, the aspect ratio can be increased by incorporating a suitable additive into the electrolytic solution.

<Regarding Cu ₂ O Layer> Next, the Cu ₂ O layer 14 functioning as a light absorbing layer will be described. Cu ₂
O is a p-type semiconductor having a bandgap of 2.0 eV to 2.2 eV and can absorb light having a wavelength shorter than red. The Cu ₂ O layer 14 is generally prepared by a method of oxidizing Cu to rapidly cool it or a film forming method such as a sputtering method. However, a plating method is a method that can fill the gaps of the ZnO needle crystals 13 at a lower cost. Are better.

In the conventional photoelectric conversion device having a laminated film type structure, electrons and holes generated in the Cu ₂ O layer have a high probability of disappearing due to recombination before being collected by the electrodes. That is, the position where electrons and holes are obtained by light absorption should be closer to the electrode or the pn junction interface in order to escape recombination. For this purpose, it is generally better that the light absorption layer is thinner. Become.

However, when the light absorption layer is thin, sufficient light absorption does not occur, and most of the light is transmitted and does not contribute to photoelectric conversion. In the present embodiment, since the p layer and the n layer are intricate with each other in a micrometer size or smaller, Cu ₂ O
The charge is effectively separated regardless of where in the layer 14 electrons and holes are generated by light absorption. This is C
ZnO needle-like crystals 13 are formed on any part of the u ₂ O layer 14.
This is because the interface with and is near.

Further, since the thickness of the Cu ₂ O layer 14 can be sufficiently secured, the light absorption can be increased.

Next, a method of manufacturing the Cu ₂ O layer 14 by plating will be described. In this embodiment, the Cu ₂ O layer 14 is formed by the electrodeposition method. Specifically, it is prepared by using three electrodes or two electrodes and immersing the electrode substrate in an electrolytic solution containing at least copper ions to apply a potential.

The Cu ₂ O layer 14 can be formed, for example, by the manufacturing apparatus shown in FIG. The reference electrode 51, the counter electrode 52, and the electrode 53 (for example, the substrate 11 to which the ZnO acicular crystals 13 are attached), which is the working electrode, are immersed in the electrolytic solution 55 in the beaker 54 and an electric potential is applied to the electrode 53. Cu ₂ O crystal grows to form a Cu ₂ O layer 14.

The production conditions include an electrolytic solution containing at least a copper salt, a concentration, an electrolytic solvent such as IPA and water, an electrolytic potential value, an electrolytic solution temperature, an electrodeposition time, an active gas concentration such as oxygen, an electrolytic solution. Optimum conditions can be found by changing parameters such as convection conditions, complexing agents, and other additives.

Examples of the compound which can be used as the salt containing copper include copper nitrate, copper sulfate, copper chloride, copper carbonate, copper acetate and the like. As an example of the Cu ₂ O precipitation conditions, when a CuSO ₄ copper salt is used, it is preferable to mix a complexing agent and an alkaline solution for adjusting the pH.

At this time, the complexing agent is preferably lactic acid. At this time, the concentration of lactic acid is preferably 2 times or more that of CuSO ₄ , and more preferably 4 times or more because complexing is easier. In addition, CuSO ₄ has a concentration of 0.1 mol / L to 0.5 mol as the concentration before mixing the alkaline solution.
/ L is preferable because it can be more easily produced.

Further, it is preferable to use an aqueous solution of sodium hydroxide in the process of mixing the alkaline solution for adjusting the pH. Further, the pH is preferably 7 to 13, and more preferably 8 to 12 in consideration of crystallinity. The electrolytic potential cannot be unconditionally specified because it depends on pH and electrolyte temperature, but it tends to be preferably -0.2 V to -0.8 V using a silver / silver chloride reference electrode.

<Regarding Electrodes> As the transparent electrodes 12 and 17, general Sn-doped indium oxide, F or S is used.
b-doped tin oxide and Ga or Al-doped ZnO
Etc. are available. A sputtering method, a CVD method, or the like can be used for forming these films.

Any metal electrode 16 connected to the n-type and p-type semiconductor crystal layers may be used as long as it can form an ohmic junction with the semiconductor. A sputtering method, a CVD method, or the like can be used to manufacture the electrodes 12, 16, and 17, but a plating method can also be used.

<Regarding the Substrate> The material and thickness of the substrate 11 can be appropriately designed according to the durability required for the photovoltaic device. As the substrate 11 on the light incident side, a glass substrate, a transparent ceramic substrate, a plastic substrate or the like is preferably used as long as it is translucent. As the substrate 11 not on the light incident side, a metal substrate, a ceramic substrate, or the like can be used as appropriate. An antireflection film made of SiO ₂ or the like is preferably provided on the surface on the light incident side.

Note that the above-mentioned electrode may also serve as the substrate 11 so that the substrate, which is a member separate from the electrode, may not be provided.

Further, in the present specification, ZnO needle crystals 13,
Although described as the Cu ₂ O layer 14, the amount of oxygen may vary slightly. That is, actually ZnO _1-X and C
It is expressed as u _2−X O, and X has a variation of about 0 to 0.2.
In addition, an n-type semiconductor, p
It does not matter if the characteristics of the type semiconductor are not impaired.

[0061]

EXAMPLES The present invention will be further described below with reference to examples.

Example 1 In Example 1 of the present invention, FIG.
The ZnO needle crystal 13 is manufactured using the electrodeposition apparatus described in (1), and then the copper oxide (I) crystal that is the Cu ₂ O layer 14 is formed using the electrodeposition apparatus shown in FIG. The case of forming will be described as an example.

A conductive glass substrate (F-doped SnO ₂ , 10 Ω / □) was prepared as the substrate 11 and the transparent electrode 12,
This substrate 11 was immersed in a 2 mmol / L zinc nitrate aqueous solution 55 as a working electrode 53, and a potential of -1.2 V was applied to the Ag / AgCl reference electrode 51 for 5000 seconds.

At this time, the counter electrode 52 is a zinc plate, and the mantle heater 56 is used to make the electrolyte solution 55 in the beaker 54 85.
It was carried out by heating to ℃. After electrolysis, scanning electron microscope (SE
As a result of observing this sample in M), ZnO was found on the substrate surface.
The needle crystals 13 grew from the transparent electrode 12 as shown in FIG.

The diameter of the ZnO needle crystal 13 is 40 nm to 50 nm.
nm and the length was 20 to 30 times that.

After thoroughly washing the substrate 11 on which the ZnO needle crystals 13 were formed with distilled water, 0.4 mol / L copper (II) sulfate (II) was mixed with 3 mol / L lactic acid as the working electrode 53, Further, it is immersed in an electrolytic solution 55 adjusted to pH 9 with 0.5 mol / L sodium hydroxide aqueous solution, and Ag
The potential of -0.6 V is applied to the reference electrode 51 of / AgCl by 500.
It was applied for 0 seconds.

At this time, the counter electrode 52 is a copper plate, and the mantle heater 56 is used to heat the electrolytic solution 55 in the beaker 54 to 85 ° C.
It was heated to. As a result of observing this sample by SEM after electrolysis, it was found that the Cu ₂ O layer 14 on the substrate surface was copper oxide.
1 (a) so that the (I) crystal covers the ZnO needle crystal 13.
Had grown in the shape of. At this time, 13 between ZnO needle crystals
All the gaps were filled with Cu ₂ O.

A cell was assembled as an electrode 5 by sputtering gold deposition on the produced Cu ₂ O layer 14.

As a comparative example, Zn was formed on the transparent electrode 12.
An O film is formed by sputtering to a thickness of 300 nm, and then Cu
_A cell was similarly assembled using a sample in which a ₂ O film was formed by sputtering to a film thickness of 1 μm.

Then, 500 W of xenon lamp light was irradiated from the transparent electrode side. Then, the value of photocurrent due to the photoelectric conversion reaction generated at this time was measured. As a result of the measurement, the short-circuit current and the photoelectric conversion efficiency of the cell of the present invention were about 5 times larger. It is considered that this is due to the decrease in recombination due to the use of the needle crystal electrode.

In addition, the sample of the embodiment prepared here is 30
As a result of performing vacuum annealing at 0 ° C. and performing photoelectric conversion measurement again, both the short-circuit current and the photoelectric conversion efficiency were increased about twice. It is considered that this is because the moisture and defects contained in the plating were reduced.

[Embodiment 2] FIG. 4 shows an apparatus for manufacturing ZnO needle crystals 13 of a photoelectric conversion device according to Embodiment 2 of the present invention.
In this example, ZnO needle-shaped manufacturing apparatus of FIG.
O needle crystal 13 is manufactured, and Cu is formed using the electrodeposition apparatus of FIG.
_{The case where the 2} O layer 14 is formed and the photoelectric conversion device as shown in FIG.

First, the surface-oxidized Zn powder was put into the alumina crucible 45 as the raw material 44 and set in the apparatus.
Conductive glass (F-doped SnO ₂ , 10 Ω / □) having a thickness of 1 mm is used for the substrate 11 and the transparent electrode 12, and the temperature is 500 ° C.
It was set to ~ 600 ° C. Next, a nitrogen gas mixed with 1% oxygen was flown into the reaction vessel at 100 mL / min, and 2
It was kept at 0000 Pa.

The temperature of the crucible is set to 650 ° C to 750 ° C.
The Zn was gradually evaporated by heating to 60 ° C. for about 60 minutes. On the surface of the transparent electrode 12, ZnO needle crystals 13 were grown from the electrode 16 as shown in FIG. The ZnO needle crystal 13 has a diameter of 10 nm to 50 nm and a length of 20 nm.
It was 0 to 300 times.

Using this ZnO needle-shaped crystal electrode as a working electrode 53, 0.4 mol / L copper (II) sulfate was mixed in 3 mol / L lactic acid, and the pH was adjusted to 9 using 0.5 mol / L sodium hydroxide aqueous solution. Soaked in electrolyte 55
The potential of -0.6 V is 100 to the reference electrode 51 of / AgCl.
It was applied for 00 seconds. At this time, the counter electrode 52 is a copper plate,
The heating was performed by heating the electrolytic solution 55 in the beaker 54 to 85 ° C. with the mantle heater 56. After the electrolysis, the Cu ₂ O layer 14 had grown on the surface of the transparent electrode 12.

Electrodes 15 were formed on the Cu ₂ O layer 14 by sputtering gold, and the cell shown in FIG. 1A was assembled.

As a comparative example, Zn was formed on the transparent electrode 12.
An O film is formed by sputtering to a thickness of 300 nm, and then Cu
_A cell was similarly assembled using a sample in which a ₂ O film was formed by sputtering to a film thickness of 1 μm.

Then, 500 W of xenon lamp light was irradiated from the transparent electrode side. Then, the value of photocurrent due to the photoelectric conversion reaction generated at this time was measured. As a result of the measurement, the short-circuit current and the photoelectric conversion efficiency of the cell of the present invention were about 5 times larger. It is considered that this is because the recombination loss in the Cu ₂ O layer 14 was reduced by using the ZnO needle-shaped crystal electrode 13.

Here, by lowering the substrate temperature during the growth of the ZnO acicular crystals 13 and shortening the growth time, Z
A film having an average diameter of nO acicular crystals of about 500 nm and an aspect ratio of about 10 is obtained. The short circuit current of the cell in this case,
The photoelectric conversion efficiency was about twice that of the comparative example. From this, it is understood that the average diameter of the ZnO acicular crystals 13 is preferably 300 nm or less and the aspect ratio is 20 or more.

"Example 3" In Example 3 of the present invention, Zn
The case where the n-type oxide semiconductor layer 31 is formed between the O needle crystal 13 and the transparent electrode 12 will be described as an example.

The substrate 11 and the transparent electrode 12 have a thickness of 1 mm.
Using the conductive glass (F-doped SnO ₂ , 10 Ω / □), a thin film of ZnO and SnO ₂ was formed by the sputtering method. The total film thickness at this time was about 200 nm. Using this substrate 11, a ZnO needle crystal 13 and a Cu ₂ O layer 14 were formed by a plating method in the same manner as in Example 1,
The cell shown in FIG. 3 was prepared.

As a comparative example, Zn was formed on the transparent electrode 12.
An O film is formed by sputtering to a thickness of 300 nm, and then Cu
_A cell was similarly assembled using a sample in which a ₂ O film was formed by sputtering to a film thickness of 1 μm.

Then, 500 W of xenon lamp light was irradiated from the transparent electrode side. Then, the value of photocurrent due to the photoelectric conversion reaction generated at this time was measured. As a result of the measurement, the photoelectric conversion efficiency of the cell of the present invention was about eight times higher. This is Z
It is considered that this is because the leak current is reduced and the open circuit voltage is increased by using the n-type oxide semiconductor layer 31 under the nO needle crystal 13.

[0084]

As described above, according to the constitution of the present invention, it is possible to provide a method for manufacturing a photoelectric conversion device which has a low recombination loss in the light absorption layer and has a high conversion efficiency.

Further, according to the manufacturing method of the present invention, it is possible to provide a manufacturing method of a photoelectric conversion device having a semiconductor electrode in which the p-type semiconductor layer is more reliably impregnated.

Further, according to the manufacturing method of the present invention, it is possible to provide a low-cost manufacturing method of a photoelectric conversion device by a plating method.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a photoelectric conversion device according to an embodiment of the present invention.

FIG. 2 is a ZnO needle crystal 13 of FIGS. 1 (a) and 1 (b).
It is a sectional view showing various examples of.

FIG. 3 is a diagram showing a state in which an n-type oxide semiconductor layer 31 is added to the photoelectric conversion device shown in FIG.

FIG. 4 is an apparatus for manufacturing ZnO needle crystals 13 of a photoelectric conversion device according to Example 2 of the present invention.

5 is a ZnO needle crystal 13 and a Cu ₂ O layer 14 of FIG.
2 is a schematic configuration diagram of the manufacturing apparatus of FIG.

[Explanation of symbols]

11 substrate 12, 17 transparent electrode 13 ZnO needle crystal 14 Cu ₂ O layer 15, 16 electrode 31 n-type oxide semiconductor layer 42 substrate holder 43 substrate heater 44 raw material 45 crucible 46 electrode 47 reaction vessel 48 gas introduction line 49 gas exhaust Line 51 Reference electrode 52 Counter electrode 53 Sample (reference electrode) 54 Beaker 55 Electrolyte 56 Mantle heater

Claims (8)

[Claims] 1. A photoelectric conversion device in which an n-type layer and a p-type layer are stacked and formed, wherein the n-type layer is a layer made of ZnO acicular crystals, and the p-type layer is made of Cu ₂ O. A photoelectric conversion device, which is a layer. 2. The photoelectric conversion device according to claim 1, wherein
The photoelectric conversion device, wherein the layer made of the ZnO acicular crystals is connected to an n-type oxide semiconductor layer that is a continuous film. 3. The photoelectric conversion device according to claim 2, wherein
The photoelectric conversion device, wherein the n-type oxide semiconductor layer is ZnO or SnO ₂ . 4. The photoelectric conversion device according to claim 1, wherein
The average diameter of the ZnO acicular crystals is 300 nm or less,
A photoelectric conversion device having an aspect ratio of 20 or more. 5. A photoelectric conversion device in which an n-type layer and a p-type layer are laminated and formed.
A method of manufacturing a replacement device, wherein the n-type layer is a ZnO needle-shaped crystal.
And a p-type layer made of Cu. ₂From O
And a Cu layer₂The layer consisting of O is plated
Photoelectric conversion device having a step of growing
Manufacturing method. 6. The method for manufacturing a photoelectric conversion device according to claim 5, further comprising a step of growing a layer made of the ZnO acicular crystals by plating. 7. The method for manufacturing a photoelectric conversion device according to claim 5, wherein after the step of growing the layer made of the ZnO acicular crystals by plating, the layer made of Cu ₂ O is grown by plating. A method for manufacturing a photoelectric conversion device, comprising the step of: 8. A method of manufacturing a photoelectric conversion device according to claim 5.
And the Cu ₂Growth of O layer by plating
After the step of₂O layer is 500 ℃
Characterized by having a step of heat treatment at the following temperature
Photoelectric conversion device manufacturing method.