JP2012114251A - Manufacturing method of photoelectric conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve conversion efficiency of a photoelectric conversion device.SOLUTION: A manufacturing method of a photoelectric conversion device 21 comprises: a first step of forming a film in which a metallic oxide and a metal chalcogenide are mixed on an electrode layer 2; a second step of changing the film to an intermediate layer in which a metal and the metal chalcogenide are mixed by heating the film in a reductive gas atmosphere; and a third step of changing the intermediate layer to a metal chalcogenide layer as a photoelectric conversion element by heating the intermediate layer under an atmosphere containing a chalcogen element.

Description

  The present invention relates to a photoelectric conversion device including a metal chalcogenide.

  As a photoelectric conversion device used for photovoltaic power generation, a light absorption layer by a metal chalcogenide such as a chalcopyrite-based I-III-VI compound semiconductor such as CIS or CIGS, or a II-VI compound semiconductor such as CdTe (For example, Patent Document 1).

  A photoelectric conversion device including such a metal chalcogenide has a configuration in which a plurality of photoelectric conversion cells are arranged side by side in a plane. Each photoelectric conversion cell has a lower electrode such as a metal electrode on a substrate such as glass, a photoelectric conversion layer formed of a semiconductor layer including a light absorption layer and a buffer layer, and an upper electrode such as a transparent electrode and a metal electrode. Are stacked in this order. In addition, the plurality of photoelectric conversion cells are electrically connected in series by electrically connecting the upper electrode of one adjacent photoelectric conversion cell and the lower electrode of the other photoelectric conversion cell by a connecting conductor. Yes.

  The light absorption layer is formed by heat-treating an oxide film containing a metal element formed on the lower electrode in an atmosphere containing a chalcogen element.

JP-A-6-37342

  A photoelectric conversion device including a metal chalcogenide is always required to improve conversion efficiency. This conversion efficiency indicates the rate at which sunlight energy is converted into electrical energy in the photoelectric conversion device. For example, the value of the electrical energy output from the photoelectric conversion device is the energy of sunlight incident on the photoelectric conversion device. It is derived by dividing by the value of and multiplied by 100.

  The present invention has been made in view of the above problems, and an object thereof is to improve the conversion efficiency of a photoelectric conversion device.

  The method for manufacturing a photoelectric conversion device according to an embodiment of the present invention includes a first step of forming a film in which a metal oxide and a metal chalcogenide are mixed on an electrode layer, and heating the film in a reducing gas atmosphere to A second step of changing the film to an intermediate layer mixed with metal and metal chalcogenide; and heating the intermediate layer in a chalcogen element-containing atmosphere to change the intermediate layer to a metal chalcogenide layer as a photoelectric conversion body A third step.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide a photoelectric conversion apparatus with high photoelectric conversion efficiency.

It is a schematic diagram which shows a mode that the photoelectric conversion apparatus which concerns on one Embodiment was seen from upper direction. It is a schematic diagram which shows the cross section of the photoelectric conversion apparatus in cut surface line II-II of FIG. It is sectional drawing which shows typically the mode in the middle of manufacture of a photoelectric conversion apparatus. It is sectional drawing which shows typically the mode in the middle of manufacture of a photoelectric conversion apparatus. It is sectional drawing which shows typically the mode in the middle of manufacture of a photoelectric conversion apparatus. It is sectional drawing which shows typically the mode in the middle of manufacture of a photoelectric conversion apparatus. It is sectional drawing which shows typically the mode in the middle of manufacture of a photoelectric conversion apparatus. It is sectional drawing which shows typically the mode in the middle of manufacture of a photoelectric conversion apparatus.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, parts having similar configurations and functions are denoted by the same reference numerals, and redundant description is omitted in the following description. Further, the drawings are schematically shown, and the sizes, positional relationships, and the like of various structures in the drawings are not accurately illustrated.

<(1) Configuration of photoelectric conversion device>
FIG. 1 is a top view illustrating a configuration of the photoelectric conversion device 21. 2 is a cross-sectional view of the photoelectric conversion device 21 taken along section line II-II in FIG. 1, that is, an XZ cross-sectional view of the photoelectric conversion device 21 at the position indicated by the one-dot chain line in FIG. 1 to 8 are provided with a right-handed XYZ coordinate system in which the arrangement direction of photoelectric conversion cells 10 (the horizontal direction in the drawing in FIG. 1) is the X-axis direction.

  The photoelectric conversion device 21 has a configuration in which a plurality of photoelectric conversion cells 10 are arranged in parallel on a substrate 1. In FIG. 1, only two photoelectric conversion cells 10 are shown for convenience of illustration, but there are many actual photoelectric conversion devices 21 in the horizontal direction of the drawing or in the vertical direction of the drawing perpendicular to the drawing. The photoelectric conversion cells 10 are arranged in a plane (two-dimensionally).

  Each photoelectric conversion cell 10 mainly includes a lower electrode layer 2, a photoelectric conversion layer 3, an upper electrode layer 4, and a grid electrode 5. In the photoelectric conversion device 21, the main surface on the side where the upper electrode layer 4 and the grid electrode 5 are provided is a light receiving surface. In addition, the photoelectric conversion device 21 is provided with three types of groove portions such as first to third groove portions P1, P2, and P3.

  The substrate 1 supports the plurality of photoelectric conversion cells 10 and is made of, for example, a material such as glass, ceramics, resin, or metal. Here, the board | substrate 1 shall be comprised with the blue plate glass (soda lime glass) which has a thickness of about 1-3 mm.

  The lower electrode layer 2 is a conductive layer provided on one main surface of the substrate 1. For example, molybdenum (Mo), aluminum (Al), titanium (Ti), tantalum (Ta), or gold (Au). Or a laminated structure of these metals. The lower electrode layer 2 has a thickness of about 0.2 to 1 μm and is formed by a known thin film forming method such as sputtering or vapor deposition.

  The photoelectric conversion layer 3 has a configuration in which a first semiconductor layer 31 as a light absorption layer and a second semiconductor layer 32 as a buffer layer are stacked.

  The first semiconductor layer 31 is a semiconductor layer having a first conductivity type (here, p-type conductivity type) provided on the + Z side main surface (also referred to as one main surface) of the lower electrode layer 2. And has a thickness of about 1 to 3 μm. The first semiconductor layer 31 is mainly composed of a semiconductor containing metal chalcogenide from the viewpoint of increasing conversion efficiency at low cost with a small amount of material by thinning. A metal chalcogenide is a compound of a metal element and a chalcogen element. The chalcogen element means S, Se, or Te among the VI-B group elements. Examples of metal chalcogenides include I-III-VI group compounds and II-VI group compounds.

Here, the group I-III-VI compound is a group IB element (in this specification, the name of the group is described in the old IUPAC system. Note that the group IB element is 11 in the new IUPAC system. Group III-B elements (also referred to as group 13 elements) and VI-B group elements (also referred to as group 16 elements). Examples of the I-III-VI group compound include CuInSe ₂ (also referred to as copper indium diselenide, CIS), Cu (In, Ga) Se ₂ (also referred to as copper indium diselenide / gallium, CIGS), Cu (In, Ga) (Se, S) ₂ (also referred to as diselene / copper indium gallium sulphide / CIGSS) or the like. The first semiconductor layer 31 may be formed of a thin film of a multicomponent compound semiconductor such as copper indium selenide / gallium having a thin film of selenite / copper indium sulfide / gallium as a surface layer.

  The II-VI group compound is a compound of a II-B group element (also referred to as a group 12 element) and a VI-B group element. Examples of II-VI group compounds include ZnS, ZnSe, ZnTe, CdS, CdSe, and CdTe.

  Here, it is assumed that the first semiconductor layer 31 is composed of CIGS having p-type conductivity.

  The first semiconductor layer 31 as described above is formed by a process called a coating method or a printing method. In the application method, a solution for forming a semiconductor containing an element constituting the first semiconductor layer 31 is applied onto the lower electrode layer 2, and thereafter, drying and heat treatment are sequentially performed.

  The second semiconductor layer 32 is a semiconductor layer provided on one main surface of the first semiconductor layer 31. The second semiconductor layer 32 has a conductivity type (here, n-type conductivity type) different from that of the first semiconductor layer 31. Further, the second semiconductor layer 32 is provided in a heterojunction with the first semiconductor layer 31 mainly composed of an I-III-VI group compound semiconductor. In the photoelectric conversion cell 10, photoelectric conversion occurs in the first semiconductor layer 31 and the second semiconductor layer 32 constituting the heterojunction, and thus the first semiconductor layer 31 and the second semiconductor layer 32 are stacked. It functions as the photoelectric conversion layer 3. Note that semiconductors having different conductivity types are semiconductors having different conductive carriers. Further, as described above, when the conductivity type of the first semiconductor layer 31 is p-type, the conductivity type of the second semiconductor layer 32 may be i-type instead of n-type. Further, there may be a mode in which the conductivity type of the first semiconductor layer 31 is n-type or i-type and the conductivity type of the second semiconductor layer 32 is p-type.

The second semiconductor layer 32 includes, for example, cadmium sulfide (CdS), indium sulfide (In ₂ S ₃ ), zinc sulfide (ZnS), zinc oxide (ZnO), indium selenide (In ₂ Se ₃ ), In (OH , S), (Zn, In) (Se, OH), and (Zn, Mg) O. From the viewpoint of reducing the leakage current, the second semiconductor layer 32 can have a resistivity of 1 Ω · cm or more. The second semiconductor layer 32 is formed by, for example, a chemical bath deposition (CBD) method or the like.

  In addition, the second semiconductor layer 32 has a thickness in the normal direction of one main surface of the first semiconductor layer 31. This thickness is set to 10 to 200 nm, and from the viewpoint of suppressing damage when the upper electrode layer 4 is formed on the second semiconductor layer 32 by sputtering or the like, the thickness is set to 100 to 200 nm. Can do.

The upper electrode layer 4 is a transparent conductive film having an n-type conductivity provided on the second semiconductor layer 32, and is an electrode (also referred to as an extraction electrode) that extracts charges generated in the photoelectric conversion layer 3. is there. The upper electrode layer 4 is made of a material having a lower resistivity than the second semiconductor layer 32. The upper electrode layer 4 includes what is called a window layer, and when a transparent conductive film is further provided in addition to the window layer, these may be regarded as an integrated upper electrode layer 4.

The upper electrode layer 4 is made of a transparent, low-resistance material having a wide forbidden band, such as zinc oxide (ZnO), a compound of zinc oxide (Al, boron (B), gallium (Ga), indium (In), and A metal comprising at least one of fluorine (F), indium oxide (ITO) containing tin (Sn), and tin oxide (SnO ₂ ). It is composed of an oxide semiconductor or the like.

  The upper electrode layer 4 is formed to have a thickness of 0.05 to 3.0 μm by sputtering, vapor deposition, chemical vapor deposition (CVD), or the like. Here, from the viewpoint of good charge extraction from the photoelectric conversion layer 3, the upper electrode layer 4 can have a resistivity of less than 1 Ω · cm and a sheet resistance of 50 Ω / □ or less. .

  The second semiconductor layer 32 and the upper electrode layer 4 can be made of a material having a property (also referred to as light transmission property) that allows light to easily pass through the wavelength region of light absorbed by the first semiconductor layer 31. Thereby, a decrease in light absorption efficiency in the first semiconductor layer 31 caused by providing the second semiconductor layer 32 and the upper electrode layer 4 is suppressed.

  In addition, from the viewpoint of improving the light transmittance, the effect of preventing loss of light reflection and the light scattering effect, and further transmitting the current generated by the photoelectric conversion, the upper electrode layer 4 can have a thickness of 0.05 to 0.5 μm. Further, from the viewpoint of preventing light reflection loss at the interface between the upper electrode layer 4 and the second semiconductor layer 32, the absolute refractive index is substantially between the upper electrode layer 4 and the second semiconductor layer 32. It can be made the same.

  The grid electrodes 5 are provided apart from each other in the Y-axis direction, and each of the current collectors 5a is connected to a plurality of current collectors 5a extending in the X-axis direction and extends in the Y-axis direction. And a connecting portion 5b. The grid electrode 5 is an electrode having conductivity, and is made of a metal such as silver (Ag), for example.

  The current collector 5 a plays a role of collecting charges generated in the photoelectric conversion layer 3 and taken out in the upper electrode layer 4. If the current collector 5a is provided, the upper electrode layer 4 can be thinned.

  The charges collected by the grid electrode 5 and the upper electrode layer 4 are transmitted to the adjacent photoelectric conversion cell 10 through the connection part 45 provided in the second groove part P2. The connection part 45 is comprised by the extension part 4a of the upper electrode layer 4, and the hanging part 5c from the connection part 5b formed on it. Thereby, in the photoelectric conversion device 21, one lower electrode layer 2 of the adjacent photoelectric conversion cell 10, the other upper electrode layer 4 and the grid electrode 5 are connected to each other by the connection portion 45 provided in the second groove portion P2. The connecting conductor is electrically connected in series.

  The grid electrode 5 has a width of 50 to 400 μm so that good conductivity is ensured and a decrease in the light receiving area that affects the amount of light incident on the light absorption layer 31 is minimized. be able to.

<(2) Manufacturing method of photoelectric conversion device>
4 to 8 are cross-sectional views schematically showing a state in the process of manufacturing the photoelectric conversion device 21. Each of the cross-sectional views shown in FIGS. 4 to 8 shows a state in the middle of manufacturing a portion corresponding to the cross-section shown in FIG.

  First, as shown in FIG. 3, the lower electrode layer 2 made of Mo or the like is formed on the substantially entire surface of the cleaned substrate 1 by using a sputtering method or the like. Then, the first groove portion P1 is formed from the linear formation target position along the Y direction on the upper surface of the lower electrode layer 2 to the upper surface of the substrate 1 immediately below the formation position. The first groove portion P1 can be formed by, for example, a scribe process in which a groove process is performed by irradiating a formation target position while scanning with a laser beam by a YAG laser or the like. FIG. 4 is a diagram illustrating a state after the first groove portion P1 is formed.

  After the first groove portion P1 is formed, the first semiconductor layer 31 and the second semiconductor layer 32 are sequentially formed on the lower electrode layer 2. FIG. 5 is a diagram illustrating a state after the first semiconductor layer 31 and the second semiconductor layer 32 are formed.

  When the first semiconductor layer 31 is formed, first, a solution for forming a semiconductor for forming the first semiconductor layer 31 is prepared. A solution for forming a semiconductor includes a group I-B element, a group III-B element, and a group VI-B element (hereinafter referred to as the source element). Also dissolved or dispersed in a solvent.

  The above-mentioned solution for forming a semiconductor is applied onto one main surface of the lower electrode layer 2, and a film as a precursor (hereinafter also referred to as a precursor layer) is formed by drying. Application of the semiconductor forming solution is performed using, for example, a spin coater, screen printing, dipping, spraying, or a die coater.

  Drying for forming the precursor layer is performed in an inert atmosphere or a reducing atmosphere, and the temperature at the time of drying may be, for example, 50 to 300 ° C. Examples of the inert atmosphere include a nitrogen atmosphere. The reducing atmosphere includes a forming gas atmosphere and a hydrogen atmosphere. You may carry out to pyrolysis of an organic component in the case of this drying.

  This precursor layer is a film in which a metal oxide and a metal chalcogenide are mixed. The metal oxide and the metal chalcogenide are mixed because the metal oxide and the metal chalcogenide each form a fine region of several nm to several hundred nm, and these are mixed and dispersed in the precursor layer. The state that is.

  The metal chalcogenide in the precursor layer may be a metal chalcogenide constituting the desired first semiconductor layer 31 (for example, when the first semiconductor layer 31 is an I-III-VI group compound). In addition, a metal chalcogenide different from the first semiconductor layer 31 may be used (for example, the first semiconductor layer 31 is an I-III-VI group compound). In this case, the precursor layer contains a group I-VI compound and a group III-VI compound).

Thus, when the precursor layer is a film in which the metal oxide and the metal chalcogenide are mixed, when the precursor layer is heat-treated and becomes a polycrystalline layer of the metal chalcogenide, the crystallization proceeds well. The crystal grain size becomes large, and as a result, the photoelectric conversion efficiency becomes high. This is thought to be due to the following reasons. When the precursor layer is composed only of a metal oxide, the precursor layer is first reduced with a reducing gas in the atmosphere to become an intermediate layer mainly containing metal, and then the chalcogen element-containing gas in the atmosphere The metal is chalcogenized into a polycrystalline layer of metal chalcogenide. However, in this intermediate stage, the ease of reaction between the intermediate layer mainly containing metal and the chalcogen element-containing gas varies in the thickness direction of the intermediate layer, resulting in composition variations and particle size variations. It is difficult to improve the photoelectric conversion efficiency. On the other hand, when the precursor layer is composed only of the metal chalcogenide, during the heat treatment of the precursor layer, the metal chalcogenide uniformly reacts and sinters throughout the precursor layer, but the crystal grain size becomes small. There is a tendency, and it is difficult to improve the photoelectric conversion efficiency. On the other hand, when the metal oxide and the metal chalcogenide are mixed in the precursor layer as in the present embodiment, the metal oxide region is reduced to a metal region during the heat treatment of the precursor layer. The metal region melts and penetrates between the metal chalcogenides, resulting in a high raw material density. As a result, it is considered that crystallization proceeds well, the crystal grain size becomes large, and the first semiconductor layer 31 with high photoelectric conversion efficiency is obtained.

  From the viewpoint of good crystallization, the total number of moles of metal chalcogenide in the precursor layer can be made larger than the number of moles of metal oxide. Specifically, the total number of moles of metal chalcogenide can be 20 to 100 times the number of moles of metal oxide.

  The precursor layer in which the above metal oxide and metal chalcogenide are mixed is produced, for example, by the following method (first production method). Here, the case where the first semiconductor layer 31 is an I-III-VI group compound will be described as an example. First, metal oxide particles having an average particle diameter of 5 to 1000 nm (the metal oxide particles include, for example, group IB metal oxide particles and group III-B metal oxide particles), and an average particle diameter 5 to 1000 nm metal chalcogenide particles (I-III-VI group compound particles, I-VI group compound particles and III-VI group compound particles include, for example, I-III-VI group compound particles, I-VI group compounds A solution for forming a semiconductor in which particles and III-VI compound particles are dispersed in a solvent is prepared. And this precursor solution is apply | coated on the lower electrode layer 2, and a precursor layer is produced by drying.

  The I-III-VI group compound particles, the I-VI group compound particles, and the III-VI group compound particles as the metal chalcogenide particles are produced, for example, as follows. First, a raw material of a group I-B element, a group III-B element, and a group VI-B element (for example, a compound such as a salt or a complex containing each element) is dissolved in a solvent to prepare a raw material solution. And by heating this raw material solution, the I-III-VI group compound particle | grains which IB group element, III-B group element, and VI-B group element react, IB group element and Group I-VI compound particles formed by reacting with a group VI-B element or group III-VI compound particles formed by reacting a group III-B element and a group VI-B element are produced.

  Moreover, the IB group metal oxide particles and the III-B group metal oxide particles as the metal oxide particles are produced, for example, as follows. First, alkali is added to an aqueous solution containing a group I-B element ion and a group III-B element ion to produce a group I-B element hydroxide particle and a group III-B element hydroxide particle. . Then, these hydroxide particles are heated to produce Group I-B metal oxide particles and Group III-B metal oxide particles.

  In addition, the precursor layer in which the metal oxide and the metal chalcogenide are mixed can be manufactured by the following method (second manufacturing method). First, a raw material for a group I-B element, a group III-B element, and a group VI-B element (for example, a compound such as a salt or a complex containing each element) is dissolved in a solvent to prepare a solution for forming a semiconductor. And this semiconductor formation solution is apply | coated on the lower electrode layer 2, and the coating film containing the raw material of each element is produced. The coating film is heat-treated in an oxygen-containing atmosphere, so that the raw materials of the group IB element, the group III-B element, and the group VI-B element chemically react with each other, and the group I-III-VI compound Metal chalcogenide particles are produced as particles, group I-VI compound particles, or group III-VI compound particles. At the same time, some IB group elements and III-B group elements are oxidized to form metal oxides. As a result, a precursor layer in which metal chalcogenide and metal oxide are mixed is formed. In addition, from the viewpoint of satisfactorily producing metal chalcogenide particles from such a coated film, the IB group element, the III-B group element, and the VI-B group constituting the I-III-VI group compound are used. Single source precursors (see US Pat. No. 6,992,202) in which elements are contained in one molecule can be used as raw materials for group IB, group III-B and group VI-B elements.

By heat-treating the precursor layer as described above, the first semiconductor layer 31 that is a metal chalcogenide layer is formed. The heat treatment of the precursor layer is performed using a reducing gas atmosphere such as hydrogen and an atmosphere containing a chalcogen element constituting the metal chalcogenide of the first semiconductor layer 31 (for example, Se vapor, S vapor, H ₂ Se, H ₂ S, or the like). Atmosphere). The precursor layer may be subjected to a heat treatment in a reducing gas atmosphere and then performed in an atmosphere containing a chalcogen element. In an atmosphere containing both the reducing gas and the chalcogen element, the reduction and chalcogenization of the metal oxide are performed simultaneously. It may be done. For example, the precursor layer is heat-treated up to a maximum temperature of 500 to 600 ° C. at a temperature increase rate of 5 to 30 ° C./min in an atmosphere containing both a reducing gas and a chalcogen element.

  The second semiconductor layer 32 is formed by a solution growth method (also referred to as a CBD method). For example, cadmium acetate and thiourea are dissolved in ammonia water, and the substrate 1 on which the formation of the first semiconductor layer 31 has been performed is immersed therein, whereby the first semiconductor layer 31 is made of CdS. Two semiconductor layers 32 are formed.

  After the first semiconductor layer 31 and the second semiconductor layer 32 are formed, the lower electrode layer 2 immediately below the linear formation target position along the Y direction on the upper surface of the second semiconductor layer 32 is formed. A second groove portion P2 is formed over the upper surface. The second groove portion P2 is formed, for example, by performing scribing using a scribe needle having a scribe width of about 40 to 50 μm continuously several times while shifting the pitch. Further, the second groove portion P2 may be formed by scribing after the tip shape of the scribe needle is expanded to an extent close to the width of the second groove portion P2. Alternatively, the second groove portion P2 may be formed by fixing two or more than two scribe needles in contact with or in close proximity to each other, and performing one to several scribes. FIG. 6 is a diagram illustrating a state after the second groove portion P2 is formed. The second groove portion P2 is formed at a position slightly shifted in the X direction (in the drawing, + X direction) from the first groove portion P1.

  After the formation of the second groove P2, the transparent upper electrode layer 4 mainly composed of indium oxide (ITO) containing Sn, for example, is formed on the second semiconductor layer 32. The upper electrode layer 4 is formed by sputtering, vapor deposition, CVD, or the like. FIG. 7 is a view showing a state after the upper electrode layer 4 is formed.

  After the upper electrode layer 4 is formed, the grid electrode 5 is formed. For the grid electrode 5, for example, a conductive paste (also referred to as a conductive paste) in which a metal powder such as Ag is dispersed in a resin binder or the like is printed so as to draw a desired pattern, and this is dried and solidified. Is formed. The solidified state is the solidified state after melting when the binder used in the conductive paste is a thermoplastic resin, and the curing when the binder is a curable resin such as a thermosetting resin or a photocurable resin. Includes both later states. FIG. 8 is a diagram illustrating a state after the grid electrode 5 is formed.

  After the grid electrode 5 is formed, a third groove portion P3 is formed from the linear formation target position on the upper surface of the upper electrode layer 4 to the upper surface of the lower electrode layer 2 immediately below the formation position. The width of the third groove portion P3 is preferably about 40 to 1000 μm, for example. Further, the third groove portion P3 is preferably formed by mechanical scribing similarly to the second groove portion P2. In this way, the photoelectric conversion device 21 shown in FIGS. 1 and 2 is manufactured by forming the third groove portion P3.

<(3) Specific example>
Next, the photoelectric conversion device 21 will be described with a specific example.

Here, first, the following steps [a] to [d] were sequentially performed to prepare a semiconductor forming solution.

[A] 10 mmol (mmol) of Cu (CH ₃ CN) ₄ .PF ₆ which is an organometallic complex of an IB group element, and 20 mmol of P (C ₆ H ₅ ) ₃ which is a Lewis basic organic compound, Was dissolved in 100 ml of acetonitrile, and then the first complex solution was prepared by stirring at room temperature (for example, about 25 ° C.) for 5 hours.

[B] 40 mmol of sodium methoxide (NaOCH ₃ ) as a metal alkoxide and 40 mmol of HSeC ₆ H _{5 as} a chalcogen element-containing organic compound were dissolved in 300 ml of methanol, and then 6 mmol of InCl ₃ and 4 mmol of After dissolving GaCl ₃ , a second complex solution was prepared by stirring at room temperature for 5 hours.

  [C] To the first complex solution prepared in step [a], the second complex solution prepared in step [b] is dropped at a rate of 10 ml per minute, and a white precipitate (precipitate) is formed. occured. After completion of the dropping treatment, stirring for 1 hour at room temperature and precipitation extraction with a centrifugal separator were sequentially performed. When extracting the precipitate, the process of dispersing the precipitate once taken out by the centrifuge in 500 ml of methanol and then taking out the precipitate again by the centrifuge is repeated twice. Upon drying, a precipitate containing a single source precursor was obtained. In this single source precursor, one complex molecule contains Cu, In, and Se, or contains Cu, Ga, and Se.

  [D] A semiconductor forming solution in which the concentration of the single source precursor is 45% by mass by adding pyridine as an organic solvent to the precipitate containing the single source precursor obtained in the step [c]. Was made.

  Next, a substrate in which a lower electrode layer made of Mo or the like is formed on the surface of a substrate made of glass is prepared. After a semiconductor forming solution is applied on the lower electrode layer by a blade method, In an atmosphere containing 1000 ppm of oxygen, a film (precursor layer) was formed by drying at 300 ° C. for 10 minutes. A thick precursor layer was formed by sequentially performing the treatment including application by the blade method and subsequent drying 10 times.

When this precursor layer was analyzed by XPS analysis, it was found that CuInGaSe ₂ contained 1000 ppm of oxygen.

  Thereafter, heat treatment of the precursor layer was performed in an atmosphere of a mixed gas of hydrogen gas and selenium vapor gas. In this heat treatment, the temperature is raised from near room temperature to 550 ° C. over 5 minutes and held at 550 ° C. for 2 hours, whereby the first semiconductor layer as an example having a thickness of 2 μm and mainly made of CIGS is obtained. Been formed.

  Further, in the first semiconductor layer forming step as the above example, the processing is performed in the same manner as in the above example except that the precursor layer is formed in an atmosphere containing only nitrogen and not containing oxygen. As a result, the first semiconductor layer as Comparative Example 1 was formed.

When the precursor layer in the middle of formation of Comparative Example 1 was analyzed by XPS analysis, only CuInGaSe ₂ was observed and oxygen was not contained.

Further, in the step of forming the first semiconductor layer as the above example, the process is performed in the same manner as in the above example except that the semiconductor forming solution is formed as follows. A first semiconductor layer as 2 was formed. In the semiconductor forming solution used in Comparative Example 2, first, CuO powder, In ₂ O ₃ powder, and Ga ₂ O ₃ powder were 2: 0.
It was prepared by mixing at a molar ratio of 6: 0.4 and mixing with polyethylene glycol.

The conversion efficiencies of the photoelectric conversion devices as examples and comparative examples manufactured in this manner were measured. Regarding the conversion efficiency, a so-called steady light solar simulator is used, and the conversion efficiency under the condition that the light irradiation intensity on the light receiving surface of the photoelectric conversion device is 100 mW / cm ² and AM (air mass) is 1.5. Was measured. As a result, while the conversion efficiency of the photoelectric conversion device as Comparative Example 1 was 9% and the conversion efficiency of the photoelectric conversion device as Comparative Example 2 was 6%, the conversion of the photoelectric conversion device as Example The efficiency was 14% and was found to be excellent.

  Needless to say, all or a part of each of the above-described embodiment and various modifications can be appropriately combined within a consistent range.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Lower electrode layer 3 Photoelectric conversion layer 4 Upper electrode layer 5 Grid electrode 10 Photoelectric conversion cell 21 Photoelectric conversion device 31 1st semiconductor layer 32 2nd semiconductor layer 45 Connection part

Claims (4)

A first step of forming a film in which a metal oxide and a metal chalcogenide are mixed on the electrode layer;
A second step of heating the coating under a reducing gas atmosphere to change the coating to an intermediate layer mixed with metal and metal chalcogenide;
And a third step of changing the intermediate layer to a metal chalcogenide layer as a photoelectric conversion body by heating the intermediate layer in a chalcogen element-containing atmosphere.   The method for manufacturing a photoelectric conversion device according to claim 1, wherein the second step and the third step are performed simultaneously. The method for manufacturing a photoelectric conversion device according to claim 1, wherein H ₂ is included in the reducing gas. The method for manufacturing a photoelectric conversion device according to any one of claims 1 to 3, wherein the film includes a group I element and a group III element in at least one state of the metal oxide and the metal chalcogenide.

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