JP2010118569A - Method of manufacturing thin-film solar battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a thin-film solar battery capable of controlling a composition of an optical absorption layer using a single precursor. <P>SOLUTION: The method of manufacturing the thin-film solar battery includes: a step of preparing a first complex ion solution by blending Lewis base L and organic metal salt of Cu to attain a molar ratio (Cu/L) of 1/3 or lower and solving it in an organic solvent to prepare a solution in which first complex ions containing Cu and Lewis base L are present; a step of preparing a second complex ion solution of preparing a solution in which second complex ions containing S or Se and In or Ga are present; a step of preparing a single precursor by causing the first complex ions to react with the second complex ions to have them deposited and drying the obtained deposit to prepare the single precursor containing Cu and S or Se, In or Ga and Lewis base L; a step of forming an optical absorption layer by applying an optical absorption layer solution comprising the single precursor solved in an organic solvent on a first electrode layer, and then drying and heat-treating it to form the optical absorption layer; and a step of forming a second electrode layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a thin film solar cell having a light absorption layer between a pair of electrode layers.

  FIG. 1 shows a basic structure of a general thin film solar cell. As shown in FIG. 1, the thin-film solar cell has a first electrode layer 2 made of, for example, Mo formed on a substrate 1 made of soda lime glass, for example, and is formed on the first electrode layer 2. A light absorption layer 3 made of a compound semiconductor thin film is formed, and a transparent second electrode layer 5 made of ZnO or the like is formed on the light absorption layer 3 through a buffer layer 4 made of ZnS, CdS, or the like. .

As the light absorption layer 3 made of a compound semiconductor, a compound semiconductor thin film made of Cu (In, Ga) Se ₂ is used as one capable of obtaining high energy conversion efficiency.

Cu (In, Ga) as preparation of Se ₂ is large in the production process used and the method of using a vacuum process such as vapor deposition or sputtering, a non-vacuum process for deposition by solid or liquid phase material coating or electrodeposition Separated.

Among these, as a manufacturing method of Cu (In, Ga) Se ₂ to apply a liquid phase raw material in a non-vacuum process, individual metal salts of Cu, In, Ga, and Se are dissolved in an organic solvent, applied and dried. There are a manufacturing method in which heat treatment is performed, and a manufacturing method in which an organic compound or complex containing Cu, In, Ga, and Se elements is formed into a solution and applied and heat-treated.

The former production method using individual metal salts has a problem in that the solubility differs depending on each metal salt, so that the composition is easily separated and deposited at the time of drying, and the composition of the entire thin film tends to be nonuniform. On the other hand, in the production method using an organic compound or complex, if an ideal organic compound can be produced, the composition does not separate during drying, and theoretically, a Cu (In, Ga) Se ₂ thin film having a uniform composition is formed. It is possible to form.

For example, conventionally, a single source precursor method (Single Source Precursor method) is known. This method includes Cu, Se, In, or Ga in one organic compound. This is a method for forming a Cu (In, Ga) Se ₂ thin film by dissolving it in an organic solvent and applying and heat-treating it (see Patent Document 1).

The production method of Patent Document 1 will be specifically described. A metal salt such as Cu (CH ₃ CN) ₄ .PF ₆ and a Lewis base such as P (C ₆ H ₅ ) ₃ are reacted to produce {P (C ₆ By preparing a complex ion of a form such as H ₅ ) ₃ } ₂ Cu (CH ₃ CN) ₂ ⁺ and reacting this complex ion with a complex ion containing In or Ga and Se, Cu, In or A single precursor containing Ga and Se is produced.
US Pat. No. 6,992,202

According to the production method of Patent Document 1, if an ideal organic compound can be produced, theoretically, a uniform light absorption layer in which the ratio of Cu to (In + Ga) is 1: 1 can be formed. However, it is difficult to obtain a pure complex ion such as {P (C ₆ H ₅ ) ₃ } ₂ Cu (CH ₃ CN) ₂ ⁺ , and as a result, in addition to the target single precursor, There is a problem that a product is generated, and as a result, the composition ratio of Cu, In, Ga, and Se varies.

That is, according to the present inventors, it is difficult to obtain a pure complex ion such as {P (C ₆ H ₅ ) ₃ } ₂ Cu (CH ₃ CN) ₂ ⁺ by the production method of Patent Document 1. , A solution containing a complex ion of {P (C ₆ H ₅ ) ₃ } ₂ Cu (CH ₃ CN) ₂ ^{+ and} a complex ion containing In or Ga and Se. be _mixed, complex ion decreases containing in or Ga and Se which reacts with _{{P (C 6 H 5)} 3} 2 Cu (CH 3 CN) 2 + of complex ions, Cu, in or Ga, A precipitate containing Se and a precipitate of a compound containing Cu and Se are generated, and in addition, In or Ga may be present as complex ions in the solution above the precipitate. all right.

Therefore, when the solution above the precipitate is discharged and the remaining precipitate is dried to produce a precursor, complex ions of In or Ga in the solution are discharged and removed, and Cu and (In + Ga) In the light absorption layer produced by heat-treating this precursor, the amount of In or Ga is reduced, especially because the amount of In or Ga is small, and Ga is easily ionized. There is a problem that a light absorption layer having a ratio of Cu to (In + Ga) of 1: 1 is not obtained, a compound having low conductivity such as Cu ₂ Se is generated, and energy conversion efficiency is lowered.

  An object of this invention is to provide the manufacturing method of the thin film solar cell which can control the composition of a light absorption layer using a single precursor.

When the present inventors dissolved Lewis base L and an organometallic salt of Cu in an organic solvent to prepare a solution containing a first complex ion containing Cu and Lewis base L, Lewis base L and By blending an organic salt of Cu with a molar ratio (Cu / L) of 1/3 or less, in other words, by blending a large amount of Lewis base L and dissolving it in an organic solvent, {P It has been found that a first complex ion such as (C ₆ H ₅ ) ₃ } ₂ Cu (CH ₃ CN) ₂ ⁺ can be produced easily and in large quantities, and has led to the present invention.

  The method for producing a thin film solar cell of the present invention is a method for producing a thin film solar cell having a light absorption layer between a first electrode layer and a second electrode layer, wherein a Lewis base L and an organometallic salt of Cu are mixed with each other. Preparation of a first complex ion solution for preparing a solution containing a first complex ion containing Cu and a Lewis base L by mixing and dissolving in an organic solvent so that the ratio (Cu / L) is 1/3 or less Mixing a step, a second complex ion solution preparation step for preparing a solution containing a second complex ion containing S or Se and In or Ga, and the first complex ion solution and the second complex ion solution. A single precursor containing Cu and S or Se and In or Ga and the Lewis base L is dried by reacting the first complex ion and the second complex ion. Single precursor production process for producing a body, and using the single precursor as an organic solvent A light absorbing layer that forms the light absorbing layer containing Cu and S or Se and In or Ga by applying a heat treatment on the first electrode layer after drying the dissolved light absorbing layer solution and drying the solution. And a second electrode layer forming step of forming the second electrode layer on the light absorption layer.

In the method for producing a thin film solar cell of the present invention, when a Lewis base L and an organometallic salt of Cu are dissolved in an organic solvent to prepare a solution containing a first complex ion containing Cu and the Lewis base L, By mixing the Lewis base L and the organometallic salt of Cu so that the molar ratio (Cu / L) is 1/3 or less, the Lewis base L is added more than usual and dissolved in an organic solvent. , Suppresses the formation of by-products such as a compound of Cu and Se, and easily and a large amount of a first complex ion such as {P (C ₆ H ₅ ) ₃ } ₂ Cu (CH ₃ CN) ₂ ⁺ Can be produced.

  Therefore, when the first complex ion solution is mixed with the second complex ion solution containing S or Se and In or Ga, a large amount of the first complex ions react with the second complex ions, so that In or Ga Of complex ions containing Cu and S or Se and In or Ga and Lewis base L, and the ratio of Cu and (In + Ga) in a single precursor is close to 1: 1. Composition control can be performed.

Thereby, the first complex ion and the second complex ion are allowed to react and precipitate, and the resulting precipitate is dried to produce a single precursor, and light obtained by dissolving the single precursor in an organic solvent. When the absorption layer solution is heat-treated to produce a light absorption layer, generation of a compound having low conductivity such as Cu ₂ Se can be suppressed, and generation of Cu (In, Ga) Se ₂ can be promoted. Conversion efficiency can be improved.

  Moreover, the manufacturing method of the thin film solar cell of this invention is characterized by the said 2nd complex ion containing Se and Ga in the said structure.

  Conventionally, in a light absorption layer using Ga, the present invention can be preferably used because Ga tends to exist as a complex ion, particularly when the first complex ion and the second complex ion are reacted.

That is, conventionally, since it has been difficult to generate a first complex ion such as {P (C ₆ H ₅ ) ₃ } ₂ Cu (CH ₃ CN) ₂ ⁺ , Ga and the like that react with the first complex ion Even if it is added so that the complex ion containing Se is reduced and the ratio of Cu to Ga is 1: 1 in the charge composition, it contains Cu and Se in addition to the precipitate containing Cu, Ga and Se. A precipitate like a compound is generated, and in addition, Ga is present as a complex ion in the solution above the precipitate, and the complex ion of Ga is discharged, so that Although the proportion of Ga tended to decrease, according to the present invention, the first complex ions such as {P (C ₆ H ₅ ) ₃ } ₂ Cu (CH ₃ CN) ₂ ⁺ can be easily and in large quantities. Since it can be manufactured, the present invention is preferably used when Ga is used. Door can be.

According to the method for manufacturing a thin film solar cell of the present invention, when Lewis base L and an organometallic salt of Cu are dissolved in an organic solvent, a solution containing the first complex ions containing Cu and Lewis base L is produced. In addition, the Lewis base L and the organometallic salt of Cu are blended so that the molar ratio (Cu / L) is 1/3 or less, and more Lewis base L is blended than usual and dissolved in the organic solvent. By suppressing the formation of by-products such as a compound of Cu and Se, the first complex ions such as {P (C ₆ H ₅ ) ₃ } ₂ Cu (CH ₃ CN) ₂ ⁺ can be easily formed. And can be produced in large quantities, thereby suppressing the complex ionization of In or Ga, and promoting the generation of complex ions containing Cu and S or Se and In or Ga and Lewis base L. In a single precursor The ratio of Cu to (In + Ga) in this is close to 1: 1 Composition control can be performed that.

Accordingly, the first complex ion and the second complex ion are allowed to react and precipitate, and the resulting precipitate is dried to produce a single precursor, and the single precursor is dissolved in an organic solvent. When the light absorption layer is produced by heat-treating the layer solution, it is possible to suppress the formation of a compound having a low conductivity such as Cu ₂ Se and promote the formation of Cu (In, Ga) Se ₂ , thereby converting energy. Efficiency can be improved.

  The thin film solar cell produced by the manufacturing method of the present invention is a thin film solar cell having a light absorption layer between a pair of electrode layers. For example, as shown in FIG. A layer 2 is formed, a light absorption layer 3 made of a compound semiconductor thin film is formed on the first electrode layer 2, and a transparent second electrode layer 5 is formed on the light absorption layer 3 via a buffer layer 4. ing.

  As the substrate 1, for example, a soda lime glass substrate, a metal substrate such as Mo or SUS, a resin substrate such as polyimide, or the like can be used. A first electrode layer 2 is formed on the substrate 1, and a light absorption layer 3 is formed on the first electrode layer 2. A second electrode layer 5 is formed on the light absorption layer 3 via the buffer layer 4, and the light absorption layer 3 is sandwiched between the first electrode layer 2 and the second electrode layer 5. 1, a thin film solar cell having a light absorption layer 3 between the second electrode layers 2 and 5 is configured.

  In addition, although the example which laminated | stacked the board | substrate 1, the 1st electrode layer 2, the light absorption layer 3, the buffer layer 4, and the 2nd electrode layer 5 was demonstrated sequentially, in this invention, a pair of 1st, 2nd electrode layer 2, As long as the light absorption layer 3 is provided between the layers 5, various intermediate layers may be formed between the layers. Further, the present invention may be of a type that does not have the substrate 1, in other words, a type in which the first electrode layer 2 functions as a substrate.

As the light absorption layer 3 made of a compound semiconductor, CuInSe ₂ , CuGaSe ₂ , and Cu (In, Ga) Se ₂ , which are compound semiconductors made of a chalcopyrite structure, are used to obtain high energy conversion efficiency. .

The manufacturing method of the thin film solar cell of this invention is demonstrated. First, for example, a substrate 1 made of soda lime glass is prepared. A first electrode layer 2 is formed on the substrate 1. The first electrode layer 2 is made of any electrode material selected from molybdenum (Mo), tungsten (W), chromium (Cr), polysilicon (SiO ₂ ), metal silicide, aluminum (Al), and the like. desirable. The first electrode layer 2 can be formed by a vapor deposition method, a sputtering method, a coating method, or the like.

Next, the light absorption layer 3 is formed on the first electrode layer 2. First, a light absorption layer solution for forming the light absorption layer 3 is prepared. This light absorption layer solution is a solution in which a single precursor containing Cu, In, Ga, and Se is dissolved. This single precursor can be produced by reacting the first complex ion obtained in the first complex ion solution production step with the second complex ion obtained in the second complex ion solution production step.
(First complex ion solution preparation process)
First, a Lewis base L such as P (C ₆ H ₅ ) ₃ and an organometallic salt of Cu such as Cu (CH ₃ CN) ₄ · PF ₆ are reacted in an organic solvent such as acetonitrile to obtain {P (C _A first complex ion solution in which a first complex ion having a shape such as ₆ H ₅ ) ₃ } ₂ Cu (CH ₃ CN) ₂ ⁺ is present is prepared (first complex ion solution preparation step).

Here, as the organometallic salt of Cu, a halide such as CuCl, CuCl ₂ , CuBr, or CuI may be used, and the Lewis base L includes N or As, for example, As (C ₆ H ₅ ) ₃ or N (C ₆ H ₅ ) ₃ may be used. In addition to acetonitrile, acetone, methanol, ethanol, isopropanol, or the like can be used as an organic solvent for dissolving the Lewis base L and the organometallic salt of Cu.

And in the manufacturing method of the thin film solar cell of this invention, the Lewis base L and the organometallic salt of Cu are mix | blended so that molar ratio (Cu / L) may be 1/3 or less, These Lewis base L and Cu are mixed. It is important that the organic metal salt is mixed and the mixture is dissolved in an organic solvent. In particular, the molar ratio (Cu / L) is preferably 0.1 or more from the viewpoint of improving the reaction yield.
(Second complex ion solution preparation process)
A second complex ion containing an organic compound containing S or Se and a halide of In or Ga is prepared.

For example, an organic compound and NaOCH ₃ and an organic selenium compound or an organic sulfur compound reacts with the InCl ₃ or GaCl ₃ are reacted in a solvent consisting of methanol, In _{{SeR} 4} ^- or Ga _{{SeR} 4} ^- To form a second complex ion. Here, R is a kind selected from acrylic, allyl, alkyl, vinyl, perfluoro, and carbamate.

For example, HSeC ₆ H ₅ is used as the organic selenium compound, and HSC ₆ H ₅ is used as the organic sulfur compound. Further, a solvent such as ethanol or propanol can be used instead of methanol. Note that the first complex ion and the second complex ion may be produced in any order.
(Single precursor production process)
Next, the first complex ion and the second complex ion are reacted to produce a single precursor containing Cu, S or Se, In or Ga, and the Lewis base L. That is, by mixing a first complex ion solution containing Cu, a second complex ion solution containing In or Ga, and Se, and reacting the first complex ion and the second complex ion, Cu and A single precursor can be prepared by separating a precipitate containing S or Se, In or Ga, and a Lewis base L and a solution above the precipitate, discharging the solution portion, and drying.

The temperature when the first complex ion and the second complex ion are reacted is preferably 0 to 30 ° C., and the reaction time is preferably 1 to 5 hours. In order to remove impurities such as Na and Cl, the portion precipitated by the reaction is desirably washed using a technique such as centrifugation or filtration.
(Light absorption layer forming process)
A light absorption layer solution in which a single precursor is dissolved in an organic solvent is applied onto the first electrode layer 2 and dried, followed by heat treatment, whereby light absorption containing Cu and S or Se and In or Ga. Form a layer.

  That is, the light-absorbing layer solution is prepared by dissolving the single precursor in an organic solvent such as toluene, pyridine, xylene, and acetone. Then, this light absorption layer solution is applied on the first electrode 2 of the substrate 1 described above, dried, and then heat-treated in a reducing atmosphere to form the light absorption layer 3 on the first electrode layer 2. . The thickness of the light absorption layer 3 is, for example, 1.0 to 2.5 μm.

  The application of the light absorption layer solution onto the first electrode layer 2 is desirably performed using a spin coater, screen printing, dipping, spraying, a die coater, or the like. Drying is desirably performed in a reducing atmosphere. The temperature at the time of drying is 50-300 degreeC, for example.

  The heat treatment is desirably performed in a reducing atmosphere. In particular, any one of a nitrogen atmosphere, a forming gas atmosphere, and a hydrogen atmosphere is desirable. The reducing atmosphere during the heat treatment is preferably a reducing atmosphere in which moisture is removed through a hygroscopic agent. The absorbent is not particularly limited as long as it can remove water, but a molecular sieve or the like is preferably used. The heat treatment temperature is set to 400 ° C. to 600 ° C., for example.

After the formation of the light absorption layer 3, it is desirable to remove the high resistance layer made of Cu ₂ Se or the like on the surface by etching with a KCN aqueous solution.
(Buffer layer, second electrode layer forming step)
Thereafter, an n-type buffer layer 4 for heterojunction is formed on the light absorption layer 3. CdS, ZnS, ZnSe, ZnMgO, ZnS / ZnMgO, ZnO, InS, InSe, In (OH) ₃ , ZnInSe, ZnInS, ZnSSe, CuI, Mg Materials such as OH) ₂ are used. These can be produced by immersing a substrate formed up to the light absorption layer by a dip coating method, a CBD method (solution growth method) or the like in an aqueous solution to deposit fine particles.

  Next, a transparent second electrode layer 5 made of ITO or ZnO is formed on the buffer layer 4. It can be formed by sputtering, spraying or coating. The thickness of the buffer layer 4 is, for example, 10 to 200 nm, and the thickness of the second electrode layer 5 is, for example, 0.5 to 3.0 μm.

In the method for producing a thin film solar cell of the present invention, when producing a single precursor as a raw material for the light absorption layer solution, it is almost pure without going through an extraction process using a toxic substance such as CH ₂ Cl _2. A single precursor can be obtained, and a composition ratio such as Cu / In / Ga / Se can be controlled.

That is, when an organic metal salt of Lewis base L and Cu is dissolved in an organic solvent to prepare a solution containing a first complex ion containing Cu and Lewis base L, an organic salt of Lewis base L and Cu Is blended so that the molar ratio (Cu / L) is 1/3 or less, and more Lewis base L is blended than usual and dissolved in an organic solvent, such as a compound of Cu and Se. By suppressing the formation of by-products, the first complex ions such as {P (C ₆ H ₅ ) ₃ } ₂ Cu (CH ₃ CN) ₂ ⁺ can be easily and in large quantities, and thus, In Alternatively, complex ionization of Ga can be suppressed, and formation of complex ions containing Cu, S or Se, In or Ga, and Lewis base L can be promoted, and the ratio of Cu and (In + Ga) in a single precursor can be increased. The composition can be controlled close to 1: 1. .

Accordingly, the first complex ion and the second complex ion are allowed to react and precipitate, the precipitate is dried to produce a single precursor, and a light absorbing layer solution in which this single precursor is dissolved in an organic solvent is prepared. When a light absorption layer is produced by heat treatment, the production of a compound having low conductivity such as Cu ₂ Se can be suppressed, and the production of Cu (In, Ga) Se ₂ can be promoted, thereby improving the energy conversion efficiency. it can.

  Hereinafter, although the example and the comparative example are given and the manufacturing method of the thin film solar cell of this invention is demonstrated in detail, this invention is not limited only to a following example.

1 mmol of Cu (CH ₃ CN) ₄ .PF ₆ as the organometallic salt of copper and 10 mmol, 3 mmol and 2 mmol of P (C ₆ H ₅ ) ₃ as the Lewis base L were dissolved in 10 ml of acetonitrile, respectively. CH ₃ CN) ₄ .PF ₆ / P (C ₆ H ₅ ) ₃ molar ratios (Cu / L) were prepared as shown in Table 1, and 1/10, 1/3, and 1/2 solutions were prepared. . After confirming that these solutions were uniformly dissolved, the solution was stirred for 5 hours at room temperature with a magnetic stirrer to prepare the first complex ion solution 1 containing the first complex ions (first complex ion solution preparation step) ).

On the other hand, 4 mmol of NaOCH ₃ and 4 mmol of HSeC ₆ H ₅ were dissolved in 30 ml of methanol, and then InCl ₃ and / or GaCl ₃ was dissolved to a total of 1 mmol. After confirming complete dissolution, the mixture was stirred with a magnetic stirrer at room temperature for 5 hours to prepare a second complex ion solution 2 containing a second complex ion (second complex ion solution preparation step). Table 1 shows the charged compositions of Cu, Se, In, and Ga.

  Next, the second complex ion solution 2 was dropped into the first complex ion solution 1 at a rate of 10 ml per minute. Thereby, it was confirmed that a white precipitate was generated during the dropping. After completion of the dropwise addition, the mixture was stirred at room temperature for 1 hour with a magnetic stirrer. As a result, a precipitate was precipitated.

  In order to take out only this precipitate, the operation of separating the solvent with a centrifuge, dispersing it in 50 ml of methanol, and centrifuging it was repeated twice. As a result, it was confirmed that the residual amount of Na in the final product was 1 ppm or less.

  The precipitate was dried in vacuum at room temperature to remove the solvent to make a single precursor. Pyridine was added to this single precursor to produce a light absorption layer solution with a single precursor of 50% by mass in the total amount. This light absorbing layer solution was formed into a thin film on the first electrode layer made of Mo of the soda lime glass substrate by the doctor blade method. The thin film was applied to the first electrode layer by applying the light absorption layer solution using nitrogen gas as a carrier gas in the glove box. After the application, the soda lime glass substrate was dried for 5 minutes while being heated to 110 ° C. on a hot plate.

  After forming the thin film, heat treatment was performed in a hydrogen gas atmosphere. The heat treatment was performed by rapidly raising the temperature to 525 ° C. in 5 minutes and holding at 525 ° C. for 1 hour, followed by natural cooling to produce a compound semiconductor thin film having a thickness of 1.5 μm. Thereafter, cadmium acetate and thiourea were dissolved in ammonia, and the substrate was immersed therein to form a buffer layer made of CdS having a thickness of 0.05 μm on the compound semiconductor thin film. Furthermore, an Al-doped zinc oxide film (second electrode layer) was formed on the buffer layer by sputtering. Finally, an aluminum electrode (extraction electrode) was formed by vapor deposition to produce a thin film solar cell.

In the first complex ion preparation step, the inventors have a molar ratio (Cu / L) of Cu (CH ₃ CN) ₄ .PF ₆ / P (C ₆ H ₅ ) ₃ of 1/10, 1/3, In each case using 1/2, the composition analysis of a single precursor was performed by emission spectroscopy (ICP) and listed in Table 1.

From Table 1, when the molar ratio (Cu / L) of Cu (CH ₃ CN) ₄ .PF ₆ / P (C ₆ H ₅ ) ₃ is 1/3 or less in the first complex ion production step, A single precursor having a composition close to the charged composition is obtained, and it can be seen that the formation of Cu (In, Ga) Se ₂ can be promoted even after the heat treatment, and the energy conversion efficiency can be improved.

On the other hand, when the molar ratio (Cu / L) of Cu (CH ₃ CN) ₄ .PF ₆ / P (C ₆ H ₅ ) ₃ is 1/2, In, Ga, or Se is remarkably higher than the charged composition. You can see that it is lower. Thus, Cu (In, Ga) the amount of Se ₂ is small, it can be seen that the energy conversion efficiency is low.

It is sectional drawing which shows an example of a thin film solar cell.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... 1st electrode layer 3 ... Light absorption layer 4 ... Buffer layer 5 ... 2nd electrode layer

Claims (2)

  A method of manufacturing a thin film solar cell having a light absorption layer between a first electrode layer and a second electrode layer, wherein a molar ratio (Cu / L) of Lewis base L and an organometallic salt of Cu is 1/3. A first complex ion solution preparation step of preparing a solution containing the first complex ions containing Cu and Lewis base L and blended so as to be as follows, and S or Se and In or Ga A second complex ion solution preparation step for preparing a solution containing the second complex ions including the first complex ion solution and the second complex ion solution, and mixing the first complex ion and the second complex ion solution. A single precursor preparation step of preparing a single precursor containing Cu and S or Se and In or Ga and the Lewis base L by drying the resulting precipitate by reacting with complex ions; , A light absorption layer solution obtained by dissolving the single precursor in an organic solvent, A light absorption layer forming step of forming the light absorption layer containing Cu and S or Se and In or Ga by applying heat treatment after drying on the polar layer, and the light absorption layer on the light absorption layer And a second electrode layer forming step of forming a second electrode layer.   The method for producing a thin-film solar cell according to claim 1, wherein the second complex ion includes Se and Ga.

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