JP2018046196A - Photoelectric conversion device and manufacturing method of photoelectric conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel technique for realizing n-type or i-type cuprous oxide.SOLUTION: A photoelectric conversion device 10 includes a sheet-like p-type semiconductor substrate 12 composed of poly crystal Cu2O (cuprous oxide) added with Na (natrium) as a metal element, a p-type Cu2O thin film 14 formed on one side of the p-type semiconductor substrate, as an epitaxial layer, a transparent conductive layer 16 formed on the p-type Cu2O thin film, and a back electrode 18 composed of Au (gold) and formed on the opposite side of the p-type semiconductor substrate to the side where the p-type Cu2O thin film is formed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technology of a photoelectric conversion element that can convert light energy into electric energy.

In recent years, energy demand on a global scale has been increasing with the rapid economic development of emerging countries. As a result, the cost of fossil energy such as oil is rising. In addition, the increase in fossil energy consumption in these emerging countries has led to an increase in CO ₂ emissions on a global scale, causing serious environmental destruction. As a promising candidate for solving these problems, active use of natural energy is screamed, and in particular, expectations for solar power generation using solar cells are extremely high.

  Various materials are used for the solar cell, and main examples include single crystal silicon, polycrystalline silicon, amorphous silicon, copper indium gallium selenium compound (CIGS compound), and the like. Silicon has abundant crustal reserves, and in the case of high-purity silicon as a raw material for solar cells, it is difficult to say that it is an inexpensive material. In addition, CIGS compounds contain rare metals that are difficult to obtain due to their small reserves, and there is a limit in reducing material costs.

  Therefore, solar cells such as zinc oxide and cuprous oxide using zinc and copper whose main raw materials are extremely inexpensive and have abundant crustal reserves are being developed.

For example, many studies have been made on the technology for producing a cuprous oxide (Cu ₂ O) layer for solar cells. However, producing a high-quality Cu ₂ O layer was practically only a method using thermal oxidation at a high temperature of about 1000 ° C. In addition, although there are reports that the Cu ₂ O layer was produced at a relatively low temperature by a liquid phase method using an aqueous solution, the quality is large compared to the Cu ₂ O layer produced by a method by thermal oxidation at a high temperature. It was inferior.

Under such circumstances, in order to realize a “curved Cu ₂ O solar cell” on a flexible substrate such as plastic as a power source for wearable computing devices in the future, a low-temperature, high-quality Cu ₂ O It is essential to establish technology for producing layers. Prior to the technology for producing a high-quality Cu ₂ O layer at a low temperature, the inventors of the present application can use it as an epitaxial growth substrate indispensable for producing a high-quality Cu ₂ O layer. already devised a rate of Cu ₂ O sheet (see Patent Document 1).

Japanese Patent Laid-Open No. 2015-162650

Thus, although solar cells made of inexpensive materials are being realized, practically, high quality film formation at low temperatures and further improvement in conversion efficiency are required. In order to further improve the conversion efficiency, for example, it is one idea to fabricate a solar cell using a cuprous oxide homojunction. However, various types of p-type Cu ₂ O thin films have been devised, but n-type Cu ₂ O thin films that are difficult to produce in principle have not been satisfactory in quality.

  The present invention has been made in view of such circumstances, and one of the objects thereof is to provide a new technique for realizing n-type or i-type cuprous oxide.

In order to solve the above problems, a photoelectric conversion element according to an aspect of the present invention is provided on a p-type first semiconductor layer mainly containing polycrystalline Cu ₂ O and the first semiconductor layer. And an n-type or i-type second semiconductor layer mainly composed of Cu ₂ O. Mn is added to the second semiconductor layer.

  According to this aspect, cuprous oxide homojunction can be realized.

  A transparent conductive layer made of zinc oxide doped with aluminum and formed on the second semiconductor layer may be further provided. As a result, high conversion efficiency, which has been difficult with the conventional heterojunction of cuprous oxide, can be realized.

Another aspect of the present invention is a method for producing a photoelectric conversion element. This method includes a step of preparing a p-type first semiconductor layer containing polycrystalline Cu ₂ O as a main component, immersing the first semiconductor layer in an aqueous solution containing Mn, and forming Cu on the first semiconductor layer. Forming an n-type or i-type second semiconductor layer containing ₂ O as a main component.

  According to this aspect, a cuprous oxide homojunction can be easily formed.

  The aqueous solution may be less than 100 ° C. Thereby, the second semiconductor layer can be formed at a low temperature at which water does not evaporate.

MnCl ₂ may be added to the aqueous solution. The aqueous solution may have a MnCl ₂ concentration of 1.0 × 10 ^{−5 to} 1.0 × 10 ⁻¹ [mol / l]. Thereby, the donor density | concentration of a 2nd semiconductor layer can be made into an appropriate range.

  In the step of forming the second semiconductor layer, the first semiconductor layer may be used as one electrode, and a voltage may be applied between the one electrode and the other electrode. Thereby, the growth rate of the second semiconductor layer can be controlled.

A voltage may be applied so that the current density between one electrode and the other electrode is less than 4.0 [mA / cm ² ]. Thereby, a cuprous oxide thin film with high crystallinity can be formed.

The aqueous solution may be a mixture of copper sulfate, lactic acid and sodium hydroxide. Thereby, the n-type or i-type second semiconductor layer mainly composed of Cu ₂ O can be formed with an inexpensive material.

  It should be noted that any combination of the above-described constituent elements and a representation of the present invention converted between a method, an apparatus, a system, etc. are also effective as an aspect of the present invention. A combination of the above-described elements as appropriate can also be included in the scope of the invention for which patent protection is sought by this patent application.

  According to the present invention, homojunction of cuprous oxide can be realized.

It is a schematic sectional drawing which shows the structure of the photoelectric conversion element which concerns on 1st Embodiment. It is the schematic of the film-forming apparatus by ECD method. 3A is a view showing a surface SEM photograph of a p ^{+ -type} Cu ₂ O: Na sheet, and FIG. 3B is a surface SEM of a p-type Cu ₂ O thin film / p ^{+ -type} Cu ₂ O: Na sheet. It is a figure which shows a photograph. 4A shows an X-ray diffraction (XRD) pattern of a p ^{+ -type} Cu ₂ O: Na sheet, and FIG. 4B shows a p-type Cu ₂ O thin film / p ^{+ -type} Cu ₂ O: Na. It shows the X-ray diffraction (XRD) pattern of the seat, FIG. 4 (c) is a diagram showing an X-ray diffraction (XRD) pattern of the p-type Cu ₂ O thin film / FTO / glass. It is a schematic view showing the crystal structure of the Cu 2 _O. FIG. 6A to FIG. 6C are diagrams showing surface SEM photographs when p-type Cu ₂ O thin films are formed at different current densities on a p ^{+ -type} Cu ₂ O: Na sheet. FIG. 7A is a diagram showing an X-ray diffraction pattern when a p-type Cu ₂ O thin film is formed on a p ^{+ -type} Cu ₂ O: Na sheet at a current density of 0.25 [mA / cm ² ]. 7 (b) is a diagram showing an X-ray diffraction pattern when a p-type Cu ₂ O thin film is formed at a current density of 1.0 [mA / cm ² ] on a p ^{+ -type} Cu ₂ O: Na sheet, FIG. (C) is a diagram showing an X-ray diffraction pattern when a p-type Cu ₂ O thin film is formed at a current density of 4.0 [mA / cm ² ] on a p ^{+ -type} Cu ₂ O: Na sheet. It is the figure which showed the wavelength dependence of the external quantum efficiency (EQE) of the two heterojunction solar cells from which hole density differs, and the homojunction solar cell which concerns on 2nd Embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate.

(First embodiment)
The present inventors have studied a solar cell using a p-type polycrystalline Cu ₂ O (cuprous oxide) sheet prepared by thermally oxidizing a Cu (copper) sheet at a high temperature as an active layer. Cu ₂ O crystals are naturally produced and can be easily created using many crystal growth methods, but the introduced Cu vacancies act as acceptors and exhibit p-type conduction no matter which method is used. It was difficult to produce n-type Cu ₂ O crystals.

Therefore, in research on solar cells using Cu ₂ O, heterojunctions composed of a combination of p-type Cu ₂ O and an n-type semiconductor composed of other materials other than Cu ₂ O are widely used. Recently, the technology devised by the present inventors has realized a high conversion efficiency of 8.1 [%] in a heterojunction solar cell using p-type Cu ₂ O as an active layer. This value is close to the theoretical limit of efficiency achievable in this type of solar cell. On the other hand, in a Cu ₂ O pn junction solar cell with an energy gap of 2 [eV], a conversion efficiency of about 20 [%] can be expected theoretically.

However, the realization of the n-type Cu ₂ O layer is important for its realization. Therefore, as a first step for realizing a high-quality n-type Cu ₂ O layer that can be used as an active layer of a solar cell, in the first embodiment, a method for manufacturing a new active layer will be described. In this manufacturing method, a Cu ₂ O thin film is homoepitaxially grown on a high-quality p-type Cu ₂ O sheet devised by the inventors of the present invention by using an electrochemical solution deposition (ECD) method. .

[Photoelectric conversion element]
FIG. 1 is a schematic cross-sectional view showing the configuration of the photoelectric conversion element according to the first embodiment. The photoelectric conversion element 10 includes a sheet-shaped p-type semiconductor substrate 12 made of polycrystalline Cu ₂ O (cuprous oxide) to which Na (sodium) is added as a metal element, and a p-type semiconductor substrate 12 on one surface. a p-type Cu ₂ O thin film 14 formed as an epitaxial layer was formed on the p-type Cu ₂ O thin film 14, the transparent conductive layer 16, the p-type semiconductor substrate 12, p-type Cu ₂ O thin film 14 The back electrode 18 made of Au (gold) is formed on the surface opposite to the surface on which is formed.

The Cu ₂ O sheet that is the p-type semiconductor substrate 12 according to the present embodiment has a thickness of 10 to 1000 μm. The transparent conductive layer 16 is AZO (aluminum-doped zinc oxide).

[P-type semiconductor substrate manufacturing method]
Next, a method for manufacturing a p-type semiconductor substrate according to the present embodiment will be described. First, after washing a copper plate (purity 99.96 [%]), it is oxidized at about 1025 [° C.] to produce a polycrystalline p-type Cu ₂ O sheet (thickness 200 μm) that also serves as a substrate and an active layer. To do.

Next, the Cu ₂ O sheet is heat-treated in an atmosphere in which a metal halide exists. Examples of the metal compound include metal elements such as Na, K, Li, Mg, Ca, and Mn, and compounds such as various halogens and carbonic acid. For example, NaCl, Na ₂ CO ₃ and KCl are preferable because of easy handling and availability.

In the heat treatment process according to the present embodiment, a Cu ₂ O sheet is placed together with Na ₂ CO _{3 in} an electric furnace capable of controlling the atmosphere, and an Ar atmosphere that is an inert gas has an atmosphere temperature of 100 to 1000 [ [° C.] for 1 to 30 [h]. As the inert gas, a rare gas other than Ar or nitrogen gas may be used as appropriate. A p-type semiconductor substrate 12 made of polycrystalline Cu ₂ O is formed through such a heat treatment process.

[Method of depositing p-type Cu ₂ O thin film by ECD method]
FIG. 2 is a schematic view of a film forming apparatus using the ECD method. In the film forming apparatus 20 illustrated in FIG. 2, a solution 24 is filled in a bathtub 22. The solution 24 was prepared by adding sodium hydroxide to an aqueous solution of copper sulfate (CuSO ₄ : concentration 0.20 mol / L) and lactic acid (CH ₃ CH (OH) COOH: concentration 3.00 mol / L) to adjust the total pH to 12. It has been adjusted to. In the solution 24, a Pt sheet 26 is immersed as an anode, and the p-type semiconductor substrate 12 or the FTO transparent conductive film 28 is immersed as a cathode.

As the p-type semiconductor substrate 12, a p ^{+ -type} Cu ₂ O: Na sheet having a hole density degenerated in the order of 10 ¹⁵ [cm ⁻³ ] is used. The temperature of the solution 24 is 70 [° C.]. The temperature is measured by a thermometer 29. Further, the current density (J) is controlled by the control unit 30 so as to be a value selected in the range of 0.25 to 4.0 [mA / cm ² ]. The control unit 30 includes a power source 32, a voltmeter 34, and an ammeter 36.

Further, in the photoelectric conversion element (AZO / p-type Cu ₂ O thin film / p ^{+ -type} Cu ₂ O: Na sheet) according to Reference Example 1 using a thin film produced by the ECD method as an active layer, and Comparative Example 1 a photoelectric conversion element (AZO / p-type Cu ₂ O thin film / FTO) were prepared according, to measure the photovoltaic characteristics of the element under light irradiation ^{AM1.5G (100 [mW / cm 2} ]).

3A is a view showing a surface SEM photograph of a p ^{+ -type} Cu ₂ O: Na sheet, and FIG. 3B is a surface SEM of a p-type Cu ₂ O thin film / p ^{+ -type} Cu ₂ O: Na sheet. It is a figure which shows a photograph. As shown in FIG. 3B, it can be seen that the p-type Cu ₂ O thin film is uniformly formed on the p ^{+ -type} Cu ₂ O: Na sheet as the substrate.

4A shows an X-ray diffraction (XRD) pattern of a p ^{+ -type} Cu ₂ O: Na sheet, and FIG. 4B shows a p-type Cu ₂ O thin film / p ^{+ -type} Cu ₂ O: Na. It shows the X-ray diffraction (XRD) pattern of the seat, FIG. 4 (c) is a diagram showing an X-ray diffraction (XRD) pattern of the p-type Cu ₂ O thin film / FTO / glass. FIG. 5 is a schematic diagram showing the crystal structure of Cu ₂ O.

As can be seen from the diffraction peak of the XRD pattern shown in FIG. 4A, the p ^{+ -type} Cu ₂ O: Na sheet is a polycrystal preferentially oriented on the (110) plane of the crystal structure shown in FIG. Further, as shown in FIG. 4B, only the diffraction peak oriented in the (110) plane, which is the same as the orientation of the p ^{+ -type} Cu ₂ O: Na sheet, was observed in the p-type Cu ₂ O thin film. On the other hand, as shown in FIG. 4C, the p-type Cu ₂ O thin film formed on the FTO thin film was not oriented in a specific plane orientation.

FIG. 6A to FIG. 6C are diagrams showing surface SEM photographs when p-type Cu ₂ O thin films are formed at different current densities on a p ^{+ -type} Cu ₂ O: Na sheet. FIG. 7A is a diagram showing an X-ray diffraction pattern when a p-type Cu ₂ O thin film is formed on a p ^{+ -type} Cu ₂ O: Na sheet at a current density of 0.25 [mA / cm ² ]. 7 (b) is a diagram showing an X-ray diffraction pattern when a p-type Cu ₂ O thin film is formed at a current density of 1.0 [mA / cm ² ] on a p ^{+ -type} Cu ₂ O: Na sheet, FIG. (C) is a diagram showing an X-ray diffraction pattern when a p-type Cu ₂ O thin film is formed at a current density of 4.0 [mA / cm ² ] on a p ^{+ -type} Cu ₂ O: Na sheet.

As is apparent from FIGS. 6A to 6C, the surface morphology of the p-type Cu ₂ O thin film depends on the current density J, and the current density J is 0.25 [mA / cm ² ] and 1 In the case of 0.0 [mA / cm ² ], a particularly uniform Cu ₂ O thin film could be produced.

Thus, the manufacturing method of the active layer according to the present embodiment includes a step of preparing a semiconductor substrate made of polycrystalline Cu ₂ O to which Na is added as a metal element, and a temperature of less than 100 ° C. containing at least copper ions. Immersing the semiconductor substrate in an alkaline aqueous solution, and epitaxially growing Cu ₂ O on the semiconductor substrate to form a Cu ₂ O thin film. As a result, a high-quality Cu ₂ O active layer can be produced at a lower temperature than in the past.

In addition, in the process of forming the Cu ₂ O thin film, the growth rate of the thin film is controlled by applying a voltage between both electrodes using the p-type semiconductor substrate 12 as one electrode and the Pt sheet 26 as the other electrode. it can.

As described above, in the active layer according to the first embodiment, the p ^{+ -type} Cu ₂ O thin film is preferentially oriented in the (110) plane on the Cu ₂ O sheet by XRD evaluation, and is homoepitaxially grown. It became clear that. The current density is preferably less than 4.0 [mA / cm ² ], more preferably the current density is 1.0 [mA / cm ² ] or less, and more preferably the current density is 0.25. By setting [mA / cm ² ] ± 0.10, a high-quality Cu ₂ O thin film with high crystallinity could be produced, and an excellent solar cell could be realized by using this Cu ₂ O thin film as an active layer. .

(Second Embodiment)
In the first embodiment, a p-type Cu ₂ O thin film is homoepitaxially grown on a high-quality p-type Cu ₂ O sheet substrate by using an electrochemical solution deposition (ECD) method that is a low-temperature film formation technique. Thus, it was shown that a high-quality active layer and a photoelectric conversion element (solar cell) including the active layer can be realized. However, since Cu 2 _O thin film according to the first embodiment is p-type, in order to achieve a homozygous between p-type Cu 2 _O sheet substrate, n in the p-type Cu 2 _O sheet substrate It is necessary to form a shaped Cu ₂ O thin film.

[Method of depositing n-type Cu ₂ O thin film]
As the p-type semiconductor substrate 12, a Na-added p ⁺ Cu ₂ O: Na sheet with a hole density degenerated in the order of 10 ¹⁵ [cm ⁻³ ] is used. The p ⁺ Cu ₂ O: Na sheet was prepared by heat treatment of 800 [° C.] and 30 [h] in a Ar gas atmosphere together with Na ₂ CO ₃ on a p-type Cu ₂ O sheet prepared by thermal oxidation.

Next, CuSO ₄ having a concentration of 0.20 [mol / l] and CH ₃ CH (OH) having a concentration of 3.00 [mol / l] are added to the bathtub 22 of the film forming apparatus 20 described in the first embodiment. ) An aqueous solution containing COOH, MnCl ₂ having a concentration of 1.0 × 10 ^{−5 to} 1.0 × 10 ⁻¹ [mol / l], and NaOH for adjusting the pH to about 7.0 to 12. Meet. The produced p-type Cu ₂ O: Na sheet was immersed as a cathode, and the p ⁺ Cu ₂ O: Na substrate was formed by an electrochemical solution deposition (ECD) method as in the first embodiment. A Cu ₂ O thin film was formed on the film. The film forming conditions are such that the solution temperature is 70 [° C.], the current density is 0.25 to 4.0 [mA / cm ² ], and the film thickness of the Cu ₂ O thin film is 240 [nm].

  The solution temperature is preferably less than 100 [° C.], more preferably about 50 to 80 [° C.]. If the temperature is too high, water evaporates, so the concentration of dissolved components is not stable. Moreover, when temperature is too low, the component which cannot be melt | dissolved but precipitates will increase.

By immersing the p-type semiconductor substrate 12 in an aqueous solution containing Mn in this way, a Cu ₂ O thin film to which Mn has been added can be formed on the p-type semiconductor substrate 12, so that a homojunction of cuprous oxide can be easily formed. it can. In addition, since a Cu ₂ O thin film to which Mn is added can be formed using a low temperature aqueous solution of less than 100 ° C., a special vacuum apparatus or heating apparatus is not required, and the manufacturing cost can be drastically reduced. Further, by appropriately selecting the MnCl ₂ concentration in the aqueous solution, a donor concentration of Cu 2 _O thin film can be within a desired range. In addition, since the aqueous solution is a mixture of copper sulfate, lactic acid, and sodium hydroxide, an n-type or i-type semiconductor thin film mainly composed of Cu ₂ O can be formed using an inexpensive material.

Next, an AZO transparent electrode layer was formed on the Cu ₂ O thin film using a pulsed laser deposition (PLD) method at a film forming temperature of room temperature (RT).

Each element was irradiated with AM1.5G [100 mW / cm ² ] light, and the photovoltaic characteristics of the element were measured under the condition of 25 ° C. As for the photovoltaic characteristics, it was found that the current density at the time of film formation, pH, film thickness, MnCl ₂ concentration, etc. greatly affected the production conditions.

Next, the dependency of photovoltaic characteristics on MnCl ₂ concentration will be described. 7A is a diagram showing the relationship between the MnCl ₂ concentration and the open circuit voltage (Voc), FIG. 7B is a diagram showing the relationship between the MnCl ₂ concentration and the short-circuit current density (Jsc), and FIG. (c) is a diagram showing the relationship between MnCl ₂ concentration and the fill factor (FF), FIG. 7 (d) is a diagram showing the relationship between MnCl ₂ concentration and the conversion efficiency (eta).

The results shown in FIGS. 7A to 7D are as follows. The pH of the aqueous solution during film formation is 12, the temperature of the aqueous solution is 70 ° C., and the thickness of the Cu ₂ O thin film to be produced is 240 nm. ]. Then, to prepare a solar cell of Cu ₂ O thin film obtained in the case of changing the MnCl ₂ concentration in the range of ^{0~1.0 × 10 -1 [mol / l} ] as an active layer, the photovoltaic characteristics Was measured.

As shown in FIG. 7A, the open-circuit voltage (Voc) decreases as the MnCl ₂ concentration increases. Further, FIG. 7 (b), the as shown in FIG. 7 (c), short-circuit current density (Jsc) and the polarity factor (FF) is, MnCl ₂ concentration of ^{1.0 × 10 - [mol / l} / cm 2] That's it. As a result, the conversion efficiency (η) becomes maximum when the MnCl ₂ concentration is 1.0 × 10 ⁻⁴ [mol / l], the conversion efficiency (η) is 4.21 [%], and the open-circuit voltage (Voc) is 0. .78 [V] could be realized.

When a Cu ₂ O thin film was prepared by an ECD method using an aqueous solution in which InCl ₃ was dissolved instead of MnCl ₂ , the conversion efficiency (η) was such that the concentration of InCl ₃ was 5.0 × 10 ⁻⁴ [mol / l. ], The conversion efficiency (η) was 3.77 [%], and the open circuit voltage (Voc) was 0.71 [V]. Thus, it was found that there is a possibility that an n-type or i-type Cu ₂ O thin film can be realized by adding Mn or In to the aqueous solution. In particular, it has been clarified that by using a Cu ₂ O thin film to which Mn is added, a photoelectric conversion element having a conversion efficiency whose main component is cuprous oxide greatly exceeds 4% can be realized.

FIG. 8 is a diagram showing the wavelength dependence of the external quantum efficiency (EQE) of two heterojunction solar cells having different hole densities and the homojunction solar cell according to the second embodiment. In an element using a Cu ₂ O thin film formed by the ECD method as an active layer, such as an AZO / Cu ₂ O: Mn / Cu ₂ O: Na (p: 10 ¹⁵ ) solar cell according to the _second embodiment, As is apparent from the black circle spectrum of FIG. 8, the EQE is improved.

In addition, the hole density of the Cu ₂ O: Na thin film according to the _second embodiment is 10 as compared with the EQE spectra of the AZO / p-Cu ₂ O solar cell and the AZO / p-Cu ₂ O: Na solar cell. ^It is considered to be about ¹³ [cm ⁻³ ]. Therefore, it is presumed that at least an i-type Cu ₂ O thin film is formed by adding Mn, and a cuprous oxide homojunction can be realized by combination with a p-Cu ₂ O thin film.

Thus, the photoelectric conversion element according to the second embodiment includes a p-type semiconductor substrate (first semiconductor layer) made of polycrystalline Cu ₂ O to which Na is added, and an epitaxial layer on the p-type semiconductor substrate. Mn-doped n-type or i-type Cu ₂ O thin film (second semiconductor layer) and an n-type or i-type Cu ₂ O thin film formed on and doped with aluminum A transparent conductive layer made of zinc oxide. The n-type or i-type Cu ₂ O thin film preferably has a thickness of 80 nm to 800 nm. Thereby, high conversion efficiency which cannot be realized by the conventional heterojunction of Cu ₂ O can be realized.

  As described above, the present invention has been described with reference to the above-described embodiments. However, the present invention is not limited to the above-described embodiments, and the configurations of the embodiments are appropriately combined or replaced. Those are also included in the present invention. Further, it is possible to appropriately change the combinations and the order of the steps in each embodiment based on the knowledge of those skilled in the art and to add various modifications such as various design changes to each embodiment. Embodiments to which is added can also be included in the scope of the present invention.

10 photoelectric conversion element, 12 p-type semiconductor substrate, 14 Cu ₂ O thin film, 16 transparent conductive layer, 18 rear surface electrode, 20 film forming device, 22 bath, 24 the solution, 26 Pt sheet, 28 FTO transparent conductive film, 29 a thermometer 30 control units, 32 power supplies, 34 voltmeters, 36 ammeters.

Claims (9)

A p-type first semiconductor layer mainly composed of polycrystalline Cu ₂ O;
An n-type or i-type second semiconductor layer mainly composed of Cu ₂ O provided on the first semiconductor layer,
Mn is added to the said 2nd semiconductor layer, The photoelectric conversion element characterized by the above-mentioned.   The photoelectric conversion element according to claim 1, further comprising a transparent conductive layer made of zinc oxide doped with aluminum and formed on the second semiconductor layer. Preparing a p-type first semiconductor layer mainly composed of polycrystalline Cu ₂ O;
Immersing the first semiconductor layer in an aqueous solution containing Mn, and forming an n-type or i-type second semiconductor layer mainly composed of Cu ₂ O on the first semiconductor layer;
The manufacturing method of the photoelectric conversion element characterized by including.   The said aqueous solution is less than 100 degreeC, The manufacturing method of the photoelectric conversion element of Claim 3 characterized by the above-mentioned. The method for producing a photoelectric conversion element according to claim 3, wherein MnCl ₂ is added to the aqueous solution. The method for producing a photoelectric conversion element according to claim 5, wherein the aqueous solution has a MnCl ₂ concentration of 1.0 × 10 ^{−5 to} 1.0 × 10 ⁻¹ [mol / l].   7. The step of forming the second semiconductor layer includes using the first semiconductor layer as one electrode and applying a voltage between the one electrode and the other electrode. The manufacturing method of the photoelectric conversion element of Claim 1. 8. The process for producing a photoelectric conversion element according to claim 7, wherein a voltage is applied so that a current density between the one electrode and the other electrode is less than 4.0 [mA / cm ² ]. Method.   The method for producing a photoelectric conversion device according to any one of claims 3 to 8, wherein the aqueous solution is a mixture of copper sulfate, lactic acid, and sodium hydroxide.