JP2012049358A - Method of producing metal chalcogenide particle and method of manufacturing photoelectric conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple method of producing metal chalcogenide particles that can stably produce metal chalcogenide particles having few impurities as well as fine particle size by a simple method, and to provide a method of manufacturing a photoelectric conversion device.SOLUTION: A method of producing metal chalcogenide particles includes the steps of: preparing a material solution where chalcogen elements are dissolved, in a state of elementary substance, in a first organic solvent containing alcohol amine having an amino group and a hydroxyl group as a main component and a metal elements are also dissolved; and producing metal chalcogenide particles obtained by reacting the chalcogen element with metal element by heating the material solution.

Description

  The present invention relates to a method for producing metal chalcogenide particles and a method for producing a photoelectric conversion device using the same.

Some solar cells use a photoelectric conversion device including a light absorption layer made of a chalcopyrite-based I-III-VI group compound semiconductor such as CIGS. In the photoelectric conversion device, for example, a first electrode layer made of, for example, Mo is formed on a substrate made of soda lime glass, and the I-III-VI group compound is formed on the first electrode layer. A light absorption layer made of a semiconductor is formed. Further, a transparent second electrode layer made of ZnO or the like is formed on the light absorption layer via a buffer layer made of ZnS, CdS or the like.

  As a manufacturing method for forming a semiconductor layer constituting such a light absorption layer, a manufacturing method for reducing cost is used instead of a high-cost manufacturing method using a vacuum system such as a sputtering method which has been conventionally used. Has been developed. As such a manufacturing method, there is a method in which a semiconductor layer is manufactured using a raw material solution obtained by dispersing a raw material in a solvent.

  For example, in Patent Document 1, a metal salt is reacted with a chalcogenide salt in an organic solvent to form metal chalcogenide nanoparticles, and a semiconductor precursor film is formed using a suspension of the metal chalcogenide nanoparticles. It is disclosed.

Patent Document 2 discloses that a group I-B metal compound, a group III-B metal compound, and a group VI-B compound are mixed in an organic solvent to form chalcopyrite nanoparticles, and a photoelectric conversion element is formed using this. Is disclosed.

Special table 2002-501003 gazette JP 2008-192542 A

  However, in Patent Document 1 and Patent Document 2, a metal compound such as a metal salt or a metal complex is used as a raw material of a metal element for producing metal chalcogenide particles. Further, as a raw material for the chalcogen element, a chalcogenide salt or a compound such as an organic compound (such as a thiol) containing the chalcogen element is used. Therefore, in addition to the desired metal chalcogenide particles, there are many impurities such as counter ions and organic ligands. Even if the metal chalcogenide particles are taken out from the solution containing a large amount of impurities and washed, it is difficult to sufficiently remove the impurities. Therefore, when a film is formed using such metal chalcogenide particles and this is heat-treated to form a semiconductor layer, the impurities inhibit crystallization and a good semiconductor layer cannot be obtained or has been produced. There is a problem that impurities remain in the semiconductor layer, and the impurities lower the photoelectric conversion efficiency.

  The present invention has been completed in view of the above-described conventional problems, and its object is to provide a metal chalcogenide that can stably produce metal chalcogenide particles with a small amount of impurities and a fine particle diameter by a simple method. It is providing the manufacturing method of particle | grains, and the manufacturing method of a photoelectric conversion apparatus.

  In the method for producing metal chalcogenide particles according to an embodiment of the present invention, the chalcogen element is dissolved in a single state in the first organic solvent mainly composed of an alcohol amine having an amino group and a hydroxyl group, and the metal element is A step of producing a dissolved raw material solution, and a step of heating the raw material solution to produce metal chalcogenide particles obtained by reacting the chalcogen element and the metal element.

  A method for producing a photoelectric conversion device according to an embodiment of the present invention includes a step of producing metal chalcogenide particles by the method for producing metal chalcogenide particles, and a semiconductor layer formed by dispersing the metal chalcogenide particles in a second organic solvent. And a step of forming a film by applying a solution to the electrode layer, and a step of heating the film to react the metal chalcogenide particles to produce a semiconductor layer as a photoelectric conversion layer.

  According to the method for producing metal chalcogenide particles of the present invention, metal chalcogenide particles having a small particle size and a small particle size can be produced stably and easily.

  Moreover, according to the manufacturing method of the photoelectric converting layer of this invention, a photoelectric conversion apparatus with high photoelectric conversion efficiency can be produced.

It is a perspective view which shows an example of embodiment of the photoelectric conversion apparatus produced using the manufacturing method of the metal chalcogenide particle | grains of this invention, and the manufacturing method of a photoelectric conversion apparatus. It is sectional drawing of the photoelectric conversion apparatus of FIG. It is sectional drawing which shows the other example of embodiment of the photoelectric conversion apparatus produced using the manufacturing method of the metal chalcogenide particle | grains of this invention, and the manufacturing method of a photoelectric conversion apparatus.

  FIG. 1 is a perspective view showing an example of an embodiment of a photoelectric conversion device manufactured using the method for manufacturing metal chalcogenide particles and the method for manufacturing a photoelectric conversion device of the present invention, and FIG. 2 is a cross-sectional view thereof. FIG. 3 is a cross-sectional view showing another example of the embodiment of the photoelectric conversion device manufactured using the method for manufacturing metal chalcogenide particles and the method for manufacturing the photoelectric conversion device of the present invention (in FIGS. 1 to 3). The same symbols are attached to the same components). The photoelectric conversion device 10 includes a substrate 1 and a photoelectric conversion cell 11 provided on the substrate 1. The photoelectric conversion cell 11 includes a first electrode layer 2, a first semiconductor layer 3, a second semiconductor layer 4, and a second electrode layer 5. In the present embodiment, an example in which the first semiconductor layer 3 is a light absorption layer and the second semiconductor layer 4 is a buffer layer bonded to the first semiconductor layer 3 is not limited to this. The first semiconductor layer 3 may be a buffer layer.

  1 and 2, a photoelectric conversion device 10 is formed by arranging a plurality of photoelectric conversion cells 11. The photoelectric conversion cell 11 includes a third electrode layer 6 provided on the substrate 1 side of the first semiconductor layer 3 so as to be separated from the first electrode layer 2. The second electrode layer 5 and the third electrode layer 6 are electrically connected by the connection conductor 7 provided in the first semiconductor layer 3. The third electrode layer 6 is integrated with the first electrode layer 2 of the adjacent photoelectric conversion cell 11. With this configuration, adjacent photoelectric conversion cells 11 are connected in series. In one photoelectric conversion cell 11, the connection conductor 7 is provided so as to penetrate the first semiconductor layer 3 and the second semiconductor layer 4, and the first electrode layer 2 and the second electrode layer are provided. The first semiconductor layer 3 and the second semiconductor layer 4 sandwiched between 5 and 5 perform photoelectric conversion.

  The substrate 1 is for supporting the photoelectric conversion cell 11. Examples of the material used for the substrate 1 include glass, ceramics, resin, and metal.

  The first electrode layer 2 and the third electrode layer 6 are made of a conductor such as Mo, Al, Ti, or Au, and are formed on the substrate 1 by a sputtering method or a vapor deposition method.

The first semiconductor layer 3 is a compound semiconductor containing metal chalcogenide as a main component. The metal chalcogenide is a compound of a metal element and a chalcogen element, and the chalcogen element is S, Se, or Te among VI-B group elements. When the first semiconductor layer 3 is used as a light absorption layer, a metal chalcogenide having sensitivity to the wavelength of light incident on the photoelectric conversion device 10 is used for the first semiconductor layer 3. For example, when the photoelectric conversion device 10 is used as a solar cell, the first semiconductor layer 3 is preferably an II-VI group compound semiconductor such as CdS or an I-III-VI group compound semiconductor. The II-VI group compound semiconductor is a group II-B element (in this specification, the name of the group follows the short-period periodic table. Note that the group II-B element is a long-period periodic table of IUPAC. It is a compound semiconductor of a group 12 element and a VI-B group element (also referred to as a group 16 element). The I-III-VI group compound semiconductor is a compound semiconductor of a group IB element (also referred to as a group 11 element), a group III-B element (also referred to as a group 13 element), and a group VI-B element. It has a chalcopyrite structure and is called a chalcopyrite compound semiconductor (also called a CIS compound semiconductor).

In particular, I-III-VI group compound semiconductors can be preferably used because they have high photoelectric conversion efficiency and do not contain harmful substances such as Cd. Examples of the I-III-VI group compound semiconductor include Cu (In, Ga) Se ₂ (also referred to as CIGS), Cu (In, Ga) (Se, S) ₂ (also referred to as CIGSS), and CuInS ₂ (CIS). Also called). Cu (In, Ga) Se ₂ refers to a compound mainly composed of Cu, at least one of In and Ga, and Se, and Cu (In _x Ga _1-X ) Se ₂ (however, X is 0 ≦ X ≦ 1.) Cu (In, Ga) (Se, S) ₂ refers to a compound mainly composed of Cu, at least one of In and Ga, and at least one of Se and S.

  Such a first semiconductor layer 3 is manufactured as follows. First, a film as a precursor of the first semiconductor layer 3 is formed by applying a solution for a semiconductor layer formed by dispersing metal chalcogenide particles in an organic solvent on the substrate 1 having the first electrode layer 2. To do. The film may be a plurality of laminated bodies having different compositions.

  And the 1st semiconductor layer 3 which has a metal chalcogenide as a main component can be produced by heat-processing the said film | membrane. The metal chalcogenide particles dispersed in the semiconductor layer solution may have the same composition as or different from the metal chalcogenide constituting the first semiconductor layer 3. When metal chalcogenide particles having the same composition as that of the first semiconductor layer 3 are used, the metal chalcogenide particles can be favorably reacted with each other, and crystallization of the first semiconductor layer 3 can be facilitated. . Further, the metal chalcogenide particles have a composition different from that of the first semiconductor layer 3, and when a mixture of a plurality of types of metal chalcogenide particles is used, the ratio of the plurality of types of metal chalcogenide particles can be easily adjusted. It becomes easy to make the composition ratio of the first semiconductor layer 3 desired.

For example, when the first semiconductor layer 3 is an I-III-VI group compound semiconductor layer, when I-III-VI group compound particles are used as the metal chalcogenide particles, the I-III-VI group compound particles are bonded to each other. Thus, crystal growth can be carried out satisfactorily, and an I-III-VI group compound semiconductor layer having a large crystal grain size can be easily produced. Alternatively, when a mixture of group I-VI compound particles and group III-VI compound particles is used as the metal chalcogenide particles, the ratio of these group I-VI compound particles to group III-VI compound particles can be freely changed. Thus, the composition ratio of the formed I-III-VI group compound semiconductor layer can be easily controlled.

As a specific example, when the I-III-VI group compound semiconductor layer is CIGS, CIGS particles can be used as the metal chalcogenide particles. Alternatively, as the metal chalcogenide particles, a mixture of copper selenide (at least one of Cu ₂ Se and CuSe), indium selenide (In ₂ Se ₃ ), and gallium selenide (Ga ₂ Se ₃ ) can also be used.

Further, as the metal chalcogenide particles, a mixture of metal chalcogenide particles having the same composition as the first semiconductor layer 3 and a plurality of metal chalcogenide particles having a composition different from that of the first semiconductor layer 3 may be used. For example, when the first semiconductor layer 3 is an I-III-VI group compound semiconductor layer, the metal chalcogenide particles include I-III-VI group compound particles, I-VI group compound particles, and III-VI group compound particles. A mixture of these may also be used. Thereby, crystallization promotion and composition control can be performed satisfactorily.

  As such metal chalcogenide particles, it is desirable to use particles having an average particle size of 0.1 μm or less from the viewpoint of improving the reactivity and satisfactorily producing the first semiconductor layer 3 having large crystal grains. More preferably, the average particle size is preferably from 50 to 500 nm from the viewpoint of making the film as a precursor more dense and promoting crystallization.

  Metal chalcogen particles can be produced as follows. First, a raw material solution in which a chalcogen element is dissolved in a single state and a metal element is dissolved in a first organic solvent whose main component is an alcohol amine having an amino group and a hydroxyl group in one molecule is prepared. . Examples of the alcohol amine having an amino group and a hydroxyl group include monoethanolamine, diethanolamine, triethanolamine, and N-methylethanolamine. There may be a plurality of hydroxyl groups or amino groups. The amino group may be any of primary, secondary and tertiary amino groups. The first organic solvent contains this alcohol amine as a main component. Having alcohol amine as the main component means that the first organic solvent contains 60 mol% or more of alcohol amine, more preferably 80 mol% or more.

  Further, the chalcogen element constituting the metal chalcogenide particles is dissolved in the first organic solvent in a single state. The fact that the chalcogen element is dissolved in the simple substance state means that the chalcogen element is not formed into a compound with other elements, but is dissolved directly in the first organic solvent. Say. Thereby, it can suppress that unnecessary elements other than a chalcogen element mix as an impurity.

  Moreover, the metal element which comprises metal chalcogenide particle | grains is melt | dissolved in this 1st organic solvent. This metal element is dissolved in the first organic solvent in a simple substance state or in a compound state such as a metal salt or a metal complex. From the viewpoint of further suppressing unwanted elements from being mixed as impurities, it is preferable that the metal element is also dissolved in the first organic solvent in a single state.

  Next, the said raw material solution is heated and the chalcogen element and metal element which were melt | dissolved in the 1st organic solvent are made to react, and metal chalcogenide particle | grains are produced. The raw material solution is heated at a temperature of 150 to 200 ° C. for 1 minute to 20 hours. As a result, metal chalcogenide particles are produced. By using a first organic solvent mainly composed of an alcohol amine having an amino group and a hydroxyl group, the metal chalcogenide particles can be stably produced as nano-sized fine particles. .

Specific examples are shown below. To monoethanolamine as the first organic solvent, copper chloride (at least one of Cu ₂ Cl and CuCl) in an amount such that Cu is 0.7 to 1 mol in composition ratio, and In is 0.6 to 0.8 mol A quantity of indium chloride (InCl ₃ ), a quantity of gallium chloride (GaCl ₃ ) such that Ga is 0.2 to 0.4 mol, and a quantity of selenium simple substance (Se) where Se is 2 to 2.5 mol. CIGS particle | grains can be produced by melt | dissolving and heating this. Alternatively, the first raw material solution Cu (at least one of _Cu 2 Cl and CuCl) and Se copper chloride amount to be 1~2mol composition ratio is dissolved and selenium single quantity to be 0.9~1.1mol A second raw material solution in which indium chloride (InCl ₃ ) in an amount of 0.9 to 1.1 mol and selenium in an amount of 1.4 to 1.6 mol are dissolved, and Ga is 0 After preparing third raw material solutions in which gallium chloride (GaCl ₃ ) in an amount of 0.9 to 1.1 mol and selenium simple substance in an amount of Se of 1.4 to 1.6 mol were respectively prepared, each of these raw materials You may mix what heated the solution. In this case, the first raw material solution in which the copper selenide particles (at least one of Cu ₂ Se and CuSe) are dispersed and the indium selenide particles (In ₂ Se ₃ ) are dispersed by heating the first to third raw material solutions. A second raw material solution and a third raw material solution in which gallium selenide particles (Ga ₂ Se ₃ ) are dispersed are prepared. By mixing these, a raw material solution in which a mixture of metal chalcogen particles is dispersed is obtained.

  In the above specific example, an example is shown in which selenium simple substance and metal chloride are dissolved in the first organic solvent, but it is more preferable to dissolve the metal simple substance instead of the salt such as metal chloride. Thereby, impurities can be further reduced. For example, when monoethanolamine, diethanolamine, or triethanolamine is used as the first organic solvent, gallium can be directly dissolved in a metal state.

  The raw material solution in which the metal chalcogenide particles are dispersed in this way is applied as it is on the first electrode layer 2 as a solution for a semiconductor layer and dried to form a film as a precursor of the first semiconductor layer 3. May be. In this case, the process can be simplified. Alternatively, the metal chalcogenide particles are taken out by adding a low polarity organic solvent such as hexane to the raw material solution in which the metal chalcogenide particles are dispersed to precipitate the metal chalcogenide particles. The metal chalcogenide particles taken out may be dispersed to form a semiconductor layer solution. In this case, the metal chalcogenide particles can be washed and impurities can be effectively removed. Such a second organic solvent may be the same as the first organic solvent described above, or may be another organic solvent having a high polarity such as pyridine or aniline.

  The semiconductor layer solution thus prepared is applied to the surface of the substrate 1 having the first electrode 2 by using a spin coater, screen printing, dipping, spraying, or a die coater, and dried to form a film. Drying is desirably performed in a reducing atmosphere. The temperature at the time of drying can be performed at 50-300 degreeC, for example.

And the 1st semiconductor layer 3 of thickness 1.0-2.5 micrometers can be produced by heat-processing this membrane | film | coat. The heat treatment is preferably performed in a reducing atmosphere in order to prevent oxidation and form a good semiconductor layer. In particular, the reducing atmosphere in the heat treatment is preferably any one of a nitrogen atmosphere, a forming gas atmosphere, and a hydrogen atmosphere. The heat treatment temperature is, for example, 400 ° C to 600 ° C. In this heat treatment, from the viewpoint of satisfactorily crystallizing the first semiconductor layer 3, a chalcogen element may be mixed in the atmosphere in a state such as Se vapor or H ₂ Se.

The photoelectric conversion device 10 uses the first semiconductor layer 3 as a light absorption layer, and a second semiconductor layer 4 is formed on the first semiconductor layer 3 with a thickness of 10 to 200 nm. A second electrode layer 5 is formed on the layer 4. Note that the second electrode layer 5 may be formed on the first semiconductor layer 3 without forming the second semiconductor layer 4. Alternatively, the second semiconductor layer 4 can function as an electrode without forming the second electrode layer 5.

The second semiconductor layer 4 is a semiconductor layer that forms a heterojunction with the first semiconductor layer 3. The first semiconductor layer 3 and the second semiconductor layer 4 are preferably of different conductivity types. For example, when the first semiconductor layer 3 is a p-type semiconductor, the second semiconductor layer 4 is i-type or It is an n-type semiconductor. Preferably, from the viewpoint of reducing leakage current, the second semiconductor layer is a layer having a resistivity of 1 Ω · cm or more. Examples of the second semiconductor layer 4 include CdS, ZnS, ZnO, In ₂ Se ₃ , In (OH, S), (Zn, In) (Se, OH), and (Zn, Mg) O. For example, it is formed by a chemical bath deposition (CBD) method or the like. In (OH, S) refers to a compound mainly composed of In, OH, and S. (Zn, In) (Se, OH) refers to a compound mainly composed of Zn, In, Se, and OH. (Zn, Mg) O refers to a compound mainly composed of Zn, Mg and O. In order to increase the absorption efficiency of the first semiconductor layer 3, the second semiconductor layer 4 preferably has a light transmittance with respect to the wavelength region of light absorbed by the first semiconductor layer 3.

  The second electrode layer 5 is a 0.05 to 3.0 μm transparent conductive film such as ITO or ZnO. The second electrode layer 5 is formed by sputtering, vapor deposition, chemical vapor deposition (CVD), or the like. The second electrode layer 5 is a layer having a resistivity lower than that of the second semiconductor layer 4, and is for taking out charges generated in the first semiconductor layer 3. From the viewpoint of taking out charges well, it is preferable that the resistivity of the second electrode layer 5 is less than 1 Ω · cm and the sheet resistance is 50 Ω / □ or less. The second electrode layer 5 may be a semiconductor layer having a conductivity type different from that of the first semiconductor layer, and includes what is called a window layer.

  In order to increase the absorption efficiency of the first semiconductor layer 3, it is preferable that the second electrode layer 5 has optical transparency with respect to the absorbed light of the first semiconductor layer 3. The second electrode layer 5 has a thickness of 0.05 to 0.5 μm from the viewpoint of enhancing the light transmittance and at the same time enhancing the light reflection loss prevention effect and the light scattering effect and further transmitting the current generated by the photoelectric conversion. Thickness is preferred. From the viewpoint of preventing light reflection loss at the interface between the second electrode layer 5 and the second semiconductor layer 4, the refractive indexes of the second electrode layer 5 and the second semiconductor layer 4 are equal. preferable.

  The photoelectric conversion device 10 includes a plurality of photoelectric conversion cells 11 having a configuration in which the first and second semiconductor layers 3 and 4 are sandwiched between the first and second electrode layers 1 and 5 and are electrically connected to each other. It consists of In order to easily connect adjacent photoelectric converters 11 in series, as shown in FIG. 1 and FIG. 2, the photoelectric conversion cell 11 is connected to the first electrode layer 2 on the substrate 1 side of the first semiconductor layer 3. A third electrode layer 6 is provided so as to be spaced apart. The second electrode layer 5 and the third electrode layer 6 are electrically connected by the connection conductor 7 provided in the first semiconductor layer 3.

  The connection conductor 7 is made of a material having a lower electrical resistivity than the first and second semiconductor layers 3 and 4. Such a connection conductor 7 can be formed, for example, by forming a groove penetrating the first and second semiconductor layers 3 and 4 and forming a conductor in the groove. As such a conductor, for example, after forming a groove penetrating the first and second semiconductor layers 3, 4, the connection electrode 7 is formed by forming the upper electrode layer 5 also in this groove. Alternatively, the connection conductor 7 may be formed by filling the groove with a conductive paste (see FIG. 3). In FIG. 3, when the current collecting electrode 8 is formed of a conductive paste, the connection conductor 7 is formed by filling the conductive paste in the grooves penetrating the first and second semiconductor layers 3 and 4. . Alternatively, it is possible to form the first and second semiconductor layers 3 and 4 by modifying a part of the first and second semiconductor layers 3 and 4 to lower the electric resistivity without forming the groove as described above.

  Moreover, as shown in FIGS. 1 and 2, the photoelectric conversion device 10 may have a collecting electrode 8 formed on the second electrode layer 5. The collecting electrode 8 is for reducing the electric resistance of the second electrode layer 5. For example, as shown in FIG. 1, the collector electrode 8 is formed in a linear shape from one end of the photoelectric conversion cell 11 to the connection conductor 7. Thereby, the current generated by the photoelectric conversion of the first semiconductor layer 3 is collected through the second electrode layer 5 to the current collecting electrode 8, and this current is collected to the adjacent photoelectric conversion cell 11 through the connection conductor 7. It can conduct well. Therefore, by providing the current collecting electrode 8, the current generated in the first semiconductor layer 3 can be efficiently taken out even if the second electrode layer 5 is thinned. As a result, power generation efficiency can be increased.

  The collector electrode 8 preferably has a width of 50 to 400 μm from the viewpoint of suppressing light from being blocked to the first semiconductor layer 3 and having good conductivity. The current collecting electrode 8 may have a plurality of branched portions.

  The collector electrode 8 can be formed, for example, by printing a metal paste in which a metal powder such as Ag is dispersed in a resin binder or the like in a pattern and curing it.

1: Substrate 2: First electrode layer 3: First semiconductor layer 4: Second semiconductor layer 5: Second electrode layer 6: Third electrode layer 7: Connection conductor 8: Current collecting electrode 10: Photoelectric Conversion device

Claims (6)

A step of preparing a raw material solution in which a chalcogen element is dissolved in a simple substance state and a metal element is dissolved in a first organic solvent mainly composed of an alcohol amine having an amino group and a hydroxyl group;
A method for producing metal chalcogenide particles, comprising: heating the raw material solution to produce metal chalcogenide particles obtained by reacting the chalcogen element and the metal element.   The method for producing metal chalcogenide particles according to claim 1, wherein an IB group element is used as the metal element, and the metal chalcogenide particles include an I-VI group compound.   The method for producing metal chalcogenide particles according to claim 1, wherein a group III-B element is used as the metal element, and the metal chalcogenide particles include a group III-VI compound. The manufacturing method of the metal chalcogenide particle | grains of Claim 1 which produces what contains an I-III-VI group compound as the said metal chalcogenide particle | grain using the IB group element and the III-B group element as said metal element.   5. The method for producing metal chalcogenide particles according to claim 1, wherein at least a part of the metal element is dissolved in the first organic solvent in a metal state. Producing metal chalcogenide particles by the method for producing metal chalcogenide particles according to any one of claims 1 to 5,
Applying a solution for a semiconductor layer formed by dispersing the metal chalcogenide particles in a second organic solvent on the electrode layer to form a film;
And a step of producing a semiconductor layer as a photoelectric conversion layer obtained by heating the coating and reacting the metal chalcogenide particles.

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