KR20100090379A - Preparation method for cu(inxga1-x)se2 powder - Google Patents

Abstract

PURPOSE: A method for preparing Cu(InxGa1-x)Se2 powder is provided to carry out production using a medium of normal temperature and atmospheric pressure and general solvent, thereby simplifying the production process. CONSTITUTION: A method for preparing Cu(InxGa1-x)Se2 powder comprises the steps of: preparing a reaction mixture by adding copper salt, indium salt, and selenite, and gallium salt if necessary into a medium, adding a reducing agent into the reaction mixture, and separating and drying precipitate, wherein low alcohol or alcohol solution of carbon number 1~5 is used as a solvent.

Description

Preparation method for Cu (InxGa1-x) Se2 powder

The present invention relates to a method of preparing Cu (In _x Ga _1-x ) Se ₂ powder.

The chalcopyrite compound semiconductor represented by Cu (In _x Ga _1-x ) Se ₂ has a direct transition energy band structure, and has a high light absorption coefficient, which enables the production of highly efficient solar cells even with thin films. In addition, it has excellent electrical and optical stability in the long term and is used as a light absorption layer of solar cells.

The solar cell uses CuInSe ₂ abbreviated as CIS, a tertiary compound as the light absorption layer, and the CIS thin film has 1.04 eV energy band gap with high short-circuit current, but the part of In of CuInSe ₂ is increased to obtain high efficiency by increasing open voltage. Substitution with Ga or Se with S is being studied. In case of CuGaSe ₂ , the band gap of Cu (In _x Ga _1-x ) Se ₂ compound semiconductor with Ga added is about 1.5 eV, and the band gap is increased, the open voltage is increased, and the short circuit current is lowered. It is possible to control the amount of Ga added within the range. Cu (InGa) Se ₂ compound semiconductor, abbreviated as CIGS, has a direct transition energy band structure and has the highest light absorption coefficient of 1x10 ⁵ cm ^-1 among semiconductors. It can be manufactured and has excellent electric and optical stability in the long term, making it ideal as a light absorbing layer of solar cells.

The CIS or CIGS thin film used as the light absorption layer of the solar cell includes vacuum evaporation, sputtering deposition, selenization and electrodeposition, but Cu (In) Se _{Since 2} or Cu (InGa) Se ₂ is a plural compound, the manufacturing process is very difficult and the content control is difficult. Both of these require strict process control, expensive vacuum process, and multiple steps to increase the production cost of solar cells.

Since the above-described physical chemical thin film formation process requires a high cost, a method of directly coating a substrate using CIS or CIGS powder has been devised. However, this process is based on the premise of using CIS or CIGS powder, and above all, it must be possible to economically manufacture CIS or CIGS powder.

There are various methods of preparing CIS or CIGS powder, but there are representative methods of colloid synthesis and solvothermal method.

Cu (InGa) Se ₂ as colloidal synthetic methods are US Patents 6,126,740 CuI, InI _3, GaI ₃ and using a Na ₂ Se and allowed to react at low temperature Cu (InGa) to the following heat treatment obtained the Se ₂ colloidal Cu (InGa) Se _It was reported that ₂ particles could be obtained. However, these methods require pretreatment for deoxygenation and dehydration of the solvent, all processes must be carried out in an inert atmosphere, and the production cost of the CIGS powder is high because Na ₂ Se, which is an expensive reactant, is required.

Solvent heat method, another method, can synthesize particles directly by relatively simple process. However, many researches have been conducted. However, since ethylenediamine, an expensive and toxic substance, is used as a solvent, There is a problem, the reaction temperature is still high at 180 to 280 ° C., the reaction time is long at 4 to 36 hours, and the production cost of the CIGS powder is increased due to the process conditions such as the reactor sealing during the high temperature reaction.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for economically manufacturing Cu (In) Se ₂ and Cu (InGa) Se ₂ powders, which are essential in a coating method for efficiently manufacturing a thin film as a light absorption layer of a solar cell at low cost. will be. The inventors of the present invention have found that a reaction mixture can be made of a corresponding metal salt and selenic acid in a medium of normal temperature and atmospheric pressure, reduced, and heat treated to synthesize a final compound.

According to the present invention, 1) preparing a reaction mixture by adding a copper salt, indium salt and selenic acid, if necessary, gallium salt to the medium; 2) adding a reducing agent to the reaction mixture; And 3) there is provided a method for producing a selenide powder of formula 1 comprising the step of separating and drying the precipitate.

Equation 1

Cu (In _x Ga _1-x ) Se ₂

Where x is greater than or equal to 0 and less than or equal to 1

In the present invention, by replacing part of the indium salt with a gallium salt, the open voltage may be increased to further improve the efficiency. In the present invention, the copper salt, the indium salt, the gallium salt and the selenic acid are each added to the chemical equivalent ratio of the final selenide powder or added in excess. For example, the equivalent ratio of said copper salt: said indium salt: said gallium salt: said selenic acid is indium of selenide powder by adjusting the stoichiometric ratio based on approximately 1: 0.01-0.99: 0.01-0.99: 2 or more. The equivalence ratio of and gallium can be adjusted in various ways. In step 1), the copper salt, the indium salt, the gallium salt, and the selenic acid may be separately dispersed or dissolved in a medium, or the same medium may be added at the same time or at a time by mixing.

The medium used in the present invention is not particularly limited to a polar or nonpolar solvent or a dispersion medium, but is preferably a lower alcohol or an alcohol containing liquid having 1 to 5 carbon atoms.

The copper salt, the indium salt, and the gallium salt are not particularly limited, but are, for example, acetates, nitrates, oxalates, sulfates, carbonates, halides or oxides thereof, respectively.

The reducing agent is, for example, hydrazine, lithium aluminum hydride reducing agent (LiAlH ₄ ), sodium borohydride (NaBH ₄ ), diisobutyl aluminum hydride (DIBAH), formaldehyde, acetaldehyde, etc., preferably Is hydrazine.

In the step 3) in the present invention, the precipitate produced after the reaction is washed several times with a washing agent, for example, alcohol, centrifuged to remove impurities, and the separated product is dried at 80 to 600 ° C. for 2 to 6 hours. To dry. Such drying may be carried out under a reducing atmosphere including hydrogen, an inert atmosphere, a vacuum atmosphere or air, as the case may be.

In the present invention, the synthesis of Cu (In _x Ga _1-x ) Se ₂ is assumed to react by the following mechanism. The following mechanisms are estimates only and the present invention is not limited thereto.

CuL + medium-> Cu ²⁺ + L-medium L; Ligand

X [InL] + Medium → X [In ³⁺ ] + L-Medium L; Ligand, X = 0.01-0.99

(1-X) [GaL] + medium → (1-X) [Ga ³⁺ ] + L-medium L; Ligand

2Y [H ₂ SeO ₃ ] + medium → 4Y [H ⁺ ] + 2Y [SeO ₃ ] ^2- + medium L; Ligand, Y≥1 (including excessive addition for Se loss)

Cu ²⁺ + X [In ³⁺ ] + (1-X) [Ga ³⁺ ] + 2Y [SeO ₃ ] ^2- + medium

           ↓ Add reducing agent

Cu (In _x Ga _1-x ) Se _2Y or Cu ^o , In ^o , Ga ^o , Se ^o (CIGS form or form of metal ion)

           ↓ Self assembly or firing

Cu (In _x Ga _1-x ) Se ₂

The table below shows one embodiment of the process of the invention in process order.

Cu (In _x Ga _1-x ) Se ₂ powder manufacturing method of the present invention is prepared in a medium of normal temperature and normal pressure using a common solvent and does not use expensive toxic organic solvents or strong corrosive selenization gas This simple and significantly lower manufacturing cost.

Hereinafter, the present invention will be described in detail with reference to Examples.

<Example 1>

0.364 g of 2 mmole copper acetate and 0.584 g of indium acetate are dissolved in methanol, and the two solutions are mixed. To the solution was added a mixed solution of 0.516 g of 4 mmole of selenic acid to methanol, and stirred for 1 hour to prepare a reaction mixture. Next, 10 g of 80% hydrazine monohydrate solution is added to obtain a black precipitate. The solution containing the precipitate is stirred for 12 hours. At this time, all the reaction is carried out at room temperature. After the reaction, the resulting precipitate and solution are separated using a centrifuge, and the precipitate is washed with methanol and then centrifuged again. Repeat this process several times. The separated product is dried for 3 hours in a 500% 4% H ₂ / Ar atmosphere.

<Example 2>

0.364 g of 2 mmole copper acetate and 0.584 g of indium acetate are dissolved in methanol, and the two solutions are mixed. A solution of 0.516 g of 4 mmole of selenic acid dissolved in methanol was added to the solution, followed by stirring for 1 hour to prepare a reaction mixture. Next, 10 g of 80% hydrazine monohydrate solution is added to obtain a black precipitate. The solution containing the precipitate is stirred for 3 hours. At this time, all the reaction is carried out at room temperature. After the reaction, the resulting precipitate and solution are separated using a centrifuge, the precipitate is washed with methanol, and then centrifuged again. Repeat this process several times. The separated product is dried for 3 hours in a 500% 4% H ₂ / Ar atmosphere. An XRD pattern of the resulting CuInSe ₂ powder using D / MAX-2500V manufactured by Rigaku Corporation is shown in FIG. 1. Characteristic peaks of values of 2theta (hkl) representing CuInSe ₂ inherent crystal planes {17.1 (101), 26.6 (112), 27.7 (103), 30.9 (200), 35.5 (211), 41.9 (105), 44.1 (204) ), 47.8 (301), 52.4 (312), 62.6 (305), 64.4 (400), 70.8 (316)}.

<Example 3>

0.364 g of 2 mmole copper acetate and 0.584 g of indium acetate are dissolved in methanol, and the two solutions are mixed. A solution of 0.516 g of 4 mmole of selenic acid dissolved in methanol was added to the solution, followed by stirring for 1 hour to prepare a reaction mixture. Then, 5 g of 80% hydrazine monohydrate solution is added to obtain a black precipitate. The solution containing the precipitate is stirred for 3 hours. At this time, all the reaction is carried out at room temperature. After the reaction, the resulting precipitate and solution are separated using a centrifuge, the precipitate is washed with methanol, and then centrifuged again. Repeat this process several times. The separated product is dried for 3 hours in a 500% 4% H ₂ / Ar atmosphere.

<Example 4>

0.483 g of 2 mmole copper nitate and 0.602 g of indium nitate are dissolved in methanol, and the two solutions are mixed. To the solution was added a solution of 0.516 g of 4 mmole of selenic acid dissolved in methanol, and stirred for 1 hour to prepare a reaction mixture. Next, 10 g of 80% hydrazine monohydrate solution is added to obtain a black precipitate. The solution containing the precipitate is stirred for 3 hours. At this time, all the reaction is carried out at room temperature. After the reaction, the resulting precipitate and solution are separated using a centrifuge, the precipitate is washed with methanol, and then centrifuged again. Repeat this process several times. The separated product is dried for 3 hours in a 500% 4% H ₂ / Ar atmosphere. An XRD pattern of the resulting CuInSe ₂ powder using D / MAX-2500V manufactured by Rigaku Corporation is shown in FIG. 1. Characteristic peaks of values of 2theta (hkl) representing CuInSe ₂ inherent crystal planes {17.1 (101), 26.6 (112), 27.7 (103), 30.9 (200), 35.5 (211), 41.9 (105), 44.1 (204) ), 47.8 (301), 52.4 (312), 62.6 (305), 64.4 (400), 70.8 (316)}.

<Example 5>

0.268 g of 2 mmole copper chloride and 0.442 g of indium chloride are dissolved in methanol, and the two solutions are mixed. A solution of 0.516 g of 4 mmole of selenic acid dissolved in methanol was added to the solution, followed by stirring for 1 hour to prepare a reaction mixture. Next, 10 g of 80% hydrazine monohydrate solution is added to obtain a black precipitate. The solution containing the precipitate is stirred for 3 hours. At this time, all the reaction is carried out at room temperature. After the reaction, the resulting precipitate and solution are separated using a centrifuge, the precipitate is washed with methanol, and then centrifuged again. Repeat this process several times. The separated product is dried for 3 hours in a 500% 4% H ₂ / Ar atmosphere. An XRD pattern of the resulting CuInSe ₂ powder using D / MAX-2500V manufactured by Rigaku Corporation is shown in FIG. 1. Characteristic peaks of values of 2theta (hkl) representing CuInSe ₂ inherent crystal planes {17.1 (101), 26.6 (112), 27.7 (103), 30.9 (200), 35.5 (211), 41.9 (105), 44.1 (204) ), 47.8 (301), 52.4 (312), 62.6 (305), 64.4 (400), 70.8 (316)}.

<Example 6>

0.195 g of 2 mmole copper hydroxide and 0.0.344 g of indium hydroxide are dissolved in methanol, and the two solutions are mixed. A solution of 0.516 g of 4 mmole of selenic acid dissolved in methanol was added to the solution, followed by stirring for 1 hour to prepare a reaction mixture. Next, 10 g of 80% hydrazine monohydrate solution is added to obtain a black precipitate. The solution containing the precipitate is stirred for 3 hours. At this time, all the reaction is carried out at room temperature. After the reaction, the resulting precipitate and solution are separated using a centrifuge, the precipitate is washed with methanol and then centrifuged again. Repeat this process several times. The separated product is dried for 3 hours in a 500% 4% H ₂ / Ar atmosphere. An XRD pattern of the resulting CuInSe ₂ powder using D / MAX-2500V manufactured by Rigaku Corporation is shown in FIG. 1. Characteristic peaks of values of 2theta (hkl) representing CuInSe ₂ inherent crystal planes {17.1 (101), 26.6 (112), 27.7 (103), 30.9 (200), 35.5 (211), 41.9 (105), 44.1 (204) ), 47.8 (301), 52.4 (312), 62.6 (305), 64.4 (400), 70.8 (316)}.

<Example 7>

0.364 g of 2 mmole copper acetate, 0.409 g of 1.4 mmole indium acetate and 0.169 of 0.66 mmole gallium nitrate were dissolved in methanol, and the three solutions were mixed. A solution of 0.516 g of 4 mmole of selenic acid dissolved in methanol was added to the solution, followed by stirring for 1 hour to prepare a reaction mixture. Next, 10 g of 80% hydrazine monohydrate solution is added to obtain a black precipitate. The solution containing the precipitate is stirred for 3 hours. At this time, all the reaction is carried out at room temperature. After the reaction, the resulting precipitate and solution are separated using a centrifuge, the precipitate is washed with methanol, and then centrifuged again. Repeat this process several times. The separated product is dried for 3 hours in a 500% 4% H ₂ / Ar atmosphere.

<Example 8>

0.483 g of 2 mmole copper nitrate, 0.463 g of 1.54 mmole indium nitrate and 0.169 of 0.66 mmole gallium nitrate were dissolved in methanol, and the three solutions were mixed. A solution of 0.516 g of 4 mmole of selenic acid dissolved in methanol was added to the solution, followed by stirring for 1 hour to prepare a reaction mixture. Next, 10 g of 80% hydrazine monohydrate solution is added to obtain a black precipitate. The solution containing the precipitate is stirred for 3 hours. At this time, all the reaction is carried out at room temperature. After the reaction, the resulting precipitate and solution are separated using a centrifuge, the precipitate is washed with methanol, and then centrifuged again. Repeat this process several times. The separated product is dried for 3 hours in a 500% 4% H ₂ / Ar atmosphere.

<Example 9>

0.268 g of 2 mmole copper chloride, 0.310 g of 1.4 mmole indium chloride, and 0.169 of 0.66 mmole gallium nitrate were dissolved in methanol, and the three solutions were mixed. A solution of 0.516 g of 4 mmole of selenic acid dissolved in methanol was added to the solution, followed by stirring for 1 hour to prepare a reaction mixture. Next, 10 g of 80% hydrazine monohydrate solution is added to obtain a black precipitate. The solution containing the precipitate is stirred for 3 hours. At this time, all the reaction is carried out at room temperature. After the reaction, the resulting precipitate and solution are separated using a centrifuge, the precipitate is washed with methanol, and then centrifuged again. Repeat this process several times. The separated product is dried for 3 hours in a 500% 4% H ₂ / Ar atmosphere.

<Example 10>

0.195 g of 2 mmole copper hydroxide, 0.241 g of 1.4 mmole indium hydroxide and 0.169 0.66 mmole gallium nitrate were dissolved in methanol, and the three solutions were mixed. A solution of 0.516 g of 4 mmole of selenic acid dissolved in methanol was added to the solution, followed by stirring for 1 hour to prepare a reaction mixture. Next, 10 g of 80% hydrazine monohydrate solution is added to obtain a black precipitate. The solution containing the precipitate is stirred for 3 hours. At this time, all the reaction is carried out at room temperature. After the reaction, the resulting precipitate and solution are separated using a centrifuge, the precipitate is washed with methanol, and then centrifuged again. Repeat this process several times. The separated product is dried for 3 hours in a 500% 4% H ₂ / Ar atmosphere.

1 is an XRD pattern of CuInSe ₂ powders produced in Examples 2, 4, 5, and 6 using D / MAX-2500V manufactured by Rigaku Corporation.

Claims (6)

1) preparing a reaction mixture by adding copper salt, indium salt and selenic acid, if necessary, gallium salt to the medium; 2) adding a reducing agent to the reaction mixture; And 3) there is provided a method for producing a selenide powder of formula 1 comprising the step of separating and drying the precipitate. Equation 1 Cu (In _x Ga _1-x ) Se ₂ Where x is greater than or equal to 0 and less than or equal to 1 The method of claim 1, wherein a portion of the indium salt is replaced with a gallium salt to produce a copper-indium-gallium selenide powder comprising gallium. The method for producing selenide powder according to claim 1, wherein the copper salt, the indium salt, the gallium salt and the selenic acid are added in accordance with the chemical equivalent ratio of the final selenide powder. 4. The method of claim 3 wherein the equivalent ratio of said copper salt: said indium salt: said gallium salt: said selenic acid is approximately 1: 0.01 to 0.99: 0.01 to 0.99: 2. The method of claim 3, wherein the solvent is a lower alcohol or alcoholic alcohol solution of 1 to 5 carbon atoms and the copper salt, the indium salt, the gallium salt is their acetate, nitrate, oxalate, sulfate, carbonate, halide or oxide, respectively The reducing agent is a method for producing selenide powder is hydrazine. The method of claim 3, wherein the precipitate produced after the reaction in step 3) is repeated several times with a solvent to wash the impurities and to dry the separated product at 80 to 600 ° C. for 2 to 6 hours. .

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