KR20160059159A - Metal Calcogenide Nano Particle for Manufacturing Light Absorbing Layer of Solar Cell and Method for Manufacturing the Same - Google Patents

Abstract

The present invention relates to metal chalcogenide nanoparticles forming a light absorbing layer of a solar cell. More particularly, the present invention relates to metal chalcogenide nanoparticles which are crystalline particles containing group III elements of indium (In) and gallium (Ga) and at least one group VI element selected from the group containing sulfur (S) and selenium (Se), and to a manufacturing method thereof. According to the present invention, the metal chalcogenide nanoparticles can homogenize particle composition in an ink and can eventually form a light absorbing layer having uniform composition and increased density.

Description

Technical Field [0001] The present invention relates to a metal chalcogenide nanoparticle for manufacturing a solar cell light absorbing layer and a method for manufacturing the same,

The present invention relates to metal chalcogenide nanoparticles for manufacturing a solar cell light absorbing layer and a method for producing the same.

Recently, as concerns about environmental problems and depletion of natural resources have increased, there is no problem about environmental pollution, and there is a growing interest in solar cells as energy-efficient alternative energy sources. Solar cells are classified into silicon solar cells, thin film compound solar cells, and stacked solar cells depending on their constituents, among which silicon semiconductor solar cells have been extensively studied.

However, silicon solar cells are indirect transitional semiconductor, and their optical absorption coefficient can not absorb photons more effectively than direct-type semiconductors. In addition, high purity Si is indispensably required in order to prevent recombination of electrons and holes generated in the space charge region by prolonging the life time of the carrier, and it is required to carry out a high-purity, high- Is required. Solar cells using high-purity monocrystalline Si have the disadvantage of high efficiency and high production cost, and polycrystalline Si or amorphous-Si (Si) having low efficiency is used in order to lower the production cost. However, this has a problem that the photoelectric conversion efficiency is not high and a deterioration phenomenon occurs when used for a long time.

Therefore, in recent years, a thin film type compound solar cell has been studied and developed in order to overcome the shortcomings of the silicon solar cell.

Cu (In _1-x Ga _x ) (Se _y S _1-y ) (CI (G) S) which is an I-III-VI group belonging to a ternary compound semiconductor in the thin film type compound semiconductor has a direct transitional energy band Gap, a high optical absorption coefficient, and a very electro-optically stable material, making it a very ideal material for a light absorbing layer of a solar cell.

The CI (G) S solar cell forms a photovoltaic layer with a thickness of a few microns to form a solar cell. Vacuum evaporation, which does not require a precursor, and thin film formation using a precursor, An ink coating method has been introduced in which sputtering, electrodeposition for forming a G) S thin film, and recent application of a precursor material under a non-vacuum and heat treatment thereof. Among them, the ink coating method can lower the process cost and can produce a large area uniformly, and recent studies have been actively conducted. As the precursors used in the ink coating method, metal chalcogenide compounds, bimetallic metals Various types of compounds or metals such as particles, metal salts, or metal oxides are used.

Specifically, when a metal chalcogenide compound is used as a precursor, Cu-Se and In-Se compounds, and optionally, Ga-Se compounds are mixed or CuIn (Ga) Se ₂ particles are synthesized and used In the case of mixed particles, there is a problem that a partially uneven coating film tends to be formed, and in case of CuIn (Ga) Se ₂ , a long reaction time is required for particle growth.

On the other hand, bimetallic metal particles are synthesized by Cu-In alloy, which can solve the problem of partial unevenness and have a short particle growth rate and a short reaction time. However, the bimetallic metal particles are partially grown by selenium (Se) There is a problem that a film lacking Se or S is formed. In the case of coating a metal salt, there is a problem that a coating film having a high film density can be obtained, but a film damage or an organic residue is formed due to an anion contained in the salt .

Therefore, there is a high demand for precursor nanoparticles capable of forming a high-efficiency light absorption layer having uniform composition and increased film density by solving the above problems.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

The inventors of the present application have conducted intensive research and various experiments and have found that metal chalcogenide nanoparticles which are precursors are composed of Group III elements of indium (In) and gallium (Ga), sulfur (S) and selenium ). In the case of using this method, it is possible to uniformize the particle composition in the ink, resulting in uniform composition and increased film density It was confirmed that the light absorption layer can be formed, and the present invention has been accomplished.

Therefore, the metal chalcogenide nanoparticles forming the light absorbing layer of the solar cell according to the present invention,

Is a crystalline particle containing Group III elements of indium (In) and gallium (Ga) and at least one group VI element selected from the group consisting of sulfur (S) and selenium (Se).

In the present invention, 'chalcogenide' refers to a substance containing a group VI element such as sulfur (S) and / or selenium (Se). In one specific example, the metal chalcogenide nanoparticles May be represented by the following formula (1).

(In _1-x Ga _x ) _m (S _1-y Se _y ) _n (1)

In this formula,

0 <x <1, 0? Y? 1, 0 <n / m?

Specifically, the content ratio of S and Se to the content of In and Ga (n / m) can be _1? N / m? 8, and more specifically, (In _1-z Ga _z ) <z <1), (In 1-z Ga z) 4 Se 3 (0 <z <1), (In 1-z Ga z) 2 Se 3 (0 <z <1), (In 1-z Ga a _{z) S (0 <z <} 1), (in 1-z Ga z) 4 S 3 (0 <z <1), and the _{(in 1-z Ga z)} 2 S 3 (0 <z <1) And may be one or more selected from the group consisting of

As described above, since the metal chalcogenide nanoparticles according to the present invention include indium (In) and gallium (Ga) in one particle, compared with the case where particles containing only indium (In) , And gallium (Ga) can be formed without additional mixing of the particles, and the effect of increasing the film density of the crystalline particles and the light absorption layer is increased.

The metal chalcogenide nanoparticles may have a particle diameter of less than 100 nanometers, and more particularly, from 30 nanometers to 90 nanometers.

If the particle diameter of the nanoparticles exceeds 100 nanometers, deviation in particle size from particles containing copper (Cu), such as Cu-In, which are mixed together at the time of ink production, is large. And as a result, there is a problem that the composition in the thin film becomes uneven, which is not preferable.

As described above, the metal chalcogenide nanoparticles of the crystalline particles having the above-mentioned particle size range can be synthesized in an amine-based solvent. Specifically, the method for preparing the metal chalcogenide nanoparticles according to the present invention comprises:

(i) at least one group VI source selected from the group consisting of sulfur (S), selenium (Se), or compounds including sulfur (S) and selenium (Se) is dispersed in an amine- ;

(ii) an amine-based solvent containing an indium (In) salt and a gallium (Ga) salt to prepare a second solution;

(iii) heating the second solution, and then mixing the first solution with the second solution; And

(iv) synthesizing nanoparticles by the reaction of the mixture and purifying the nanoparticles;

. &Lt; / RTI &gt;

In one specific example, the amine-based solvent is selected from the group consisting of oleylamine, octylamine, ethanolamine, isopropanolamine, N-butylamine, isobutylamine isobutylamine, dimethanolamine, diethanolamine, dipropanolamine, dibutylamine, and benzylamine. In the present invention, at least one selected from the group consisting of isobutylamine, dimethanolamine, diethanolamine, dipropanolamine, dibutylamine and benzylamine.

In general, metal chalcogenide nanoparticles including both indium (In) and gallium (Ga) are synthesized in a water system. When such a nanoclusters are synthesized in water, small particles of several nanometers are accumulated, It was synthesized as amorphous particles as it consisted of large particles. Therefore, in the case of mixing and dispersing particles containing copper (Cu) such as Cu-In and beads for several days in order to produce an ink using the same, copper (Cu) -containing particles, which are generally only a few tens of nanometers, The variation in size is so great that mixing of the beads merely physically crushes indium (In) and gallium (Ga) containing metal chalcogenide nanoparticles of several micrometers, There is a problem in that the resulting light-absorbing layer thin film also causes occurrence of composition non-uniformity, cracking, voids and the like.

On the other hand, since the metal chalcogenide nanoparticles according to the present invention are synthesized in an amine-based solvent, the amine group of the amine-based compound binds to the surface of the particles to increase the crystallinity of the particles, As described above, are synthesized as crystalline particles having an average particle diameter of less than 100 nanometers, particularly 30 nanometers to 90 nanometers, and the amorphous metal chalcogenide of the conventional several micrometers As compared with the nanoparticles, the particle size nonuniformity in the ink is drastically reduced, so that the composition uniformity and dispersibility of the particles are increased, and as a result, a light absorption layer thin film having uniform composition and increased film density can be formed.

In order to prepare such a metal chalcogenide nanoparticle, the second solution containing the indium (In) salt and the gallium (Ga) salt is first heated and then reacted with sulfur (S), selenium (Se) (S), and selenium (Se), which are mixed with a first solution containing at least one metal source selected from the group consisting of metal chalcogenides Because growth occurs from nanoparticles, large particles of a few hundred nanometers or more can be synthesized.

In this case, the heating in the step (iii) may be performed in a temperature range of 150 to 400 degrees Celsius.

If the temperature is less than 150 ° C, the particles are not sufficiently reacted to form large irregularly aggregated particles. When the temperature exceeds 400 ° C, the main amine is not stable and mass synthesis is difficult. This is undesirable.

On the other hand, in the step (iii) of mixing the first solution and the second solution, the Group VI source is desirably added in an amount of 1 to 5 moles per mole of the indium (In) salt and the gallium (Ga) As shown in FIG.

When the Group VI source is contained in an amount of less than 1 mole, the Group VI element can not be sufficiently supplied. Therefore, a stable phase such as a metal chalcogenide can not be formed at a high yield, There is a problem that the metal can be oxidized. On the contrary, when the Group VI source is contained in excess of 5 moles, the Group VI source remains excessively as an impurity after the reaction, When the thin film is manufactured, it is not preferable since the VI source is evaporated in the heat treatment process of the thin film, and voids are formed excessively in the final thin film.

In one specific example, VI group source in the process (i) is _{Se, Na 2 Se, K 2} Se, CaSe, (CH 3) 2 Se, SeO 2, SeCl 4, H 2 SeO 3, H 2 SeO 4 , Na ₂ S, K ₂ S, CaS, (CH ₃ ) ₂ S, H ₂ SO ₄ , S, Na ₂ S ₂ O ₃ , NH ₂ SO ₃ H and their hydrates, thiourea, Thioacetamide, selenourea, and the like.

In one specific example, the salt of step (ii) is selected from the group consisting of chloride, bromide, iodide, nitrate, nitrite, sulfate, acetate ), Sulfite, acetylacetoate, and hydroxide. In the present invention,

Meanwhile, the first solution and the second solution may further include a capping agent.

The capping agent not only controls the size and phase of the metal chalcogenide nanoparticles synthesized by being included in the solution process, but also contains atoms such as N, O, S, The metal chalcogenide nanoparticles are easily bound to the surface of the metal chalcogenide nanoparticles to cover the surface, thereby preventing oxidation of the metal chalcogenide nanoparticles.

In addition, since they prevent agglomeration of synthesized metal chalcogenide nanoparticles, the first solution and the second solution can be mixed in a state in which the synthesized particles are uniformly dispersed, so that the substitution of a uniform metal Can be achieved.

Examples of such a capping agent include, but are not limited to, sodium L-tartrate dibasic dehydrate, potassium sodium tartrate, sodium acrylate, poly (sodium acrylate) But are not limited to, poly (acrylic acid sodium salt), poly (vinyl pyrrolidone), sodium citrate, trisodium citrate, disodium citrate, Sodium gluconate, sodium ascorbate, sorbitol, triethyl phosphate, ethylene diamine, propylene diamine, ethanedithiol (1,2- ethanedithiol, ethanethiol, 2-mercaptoethanol, 2-aminoethanethiol, and the like.

The present invention also provides an ink composition for producing a light absorbing layer comprising the metal chalcogenide nanoparticles.

The ink composition must contain copper (Cu), gallium (Ga) and / or indium (In) (Cu) chalcogenide nanoparticles, Cu-In bimetallic metal nanoparticles and the like, and more specifically, Cu-In bimetallic metal nanoparticles and the like . In this case, the Cu-In bimetallic metal nanoparticles may be at least one selected from the group consisting of Cu ₁₁ In ₉ , Cu ₁₆ In ₄ , Cu ₂ In, Cu ₇ In ₄ , and Cu ₄ In, No.

The inventors of the present application have confirmed that the bimetallic metal nanoparticles are stable not only in oxidation but also in volume due to the addition of element VI in the selenization process by heat treatment Thereby providing an effect of forming a high-density film. Therefore, in the case of an ink composition prepared by mixing the metal chalcogenide nanoparticles with Cu-In bimetallic metal nanoparticles, the VI group content in the final film due to the VI group element contained in the ink composition, A high quality light absorbing layer thin film can be formed.

In this case, the metal chalcogenide nanoparticles included in the ink composition and the Cu-In bimetallic metal nanoparticles may be mixed in a range of 0.5 <Cu / (In + Ga) <1.5.

If the composition ratio exceeds 1.5 mol, Cu-In bimetallic metal nanoparticles are more likely to be contained. If the composition ratio is less than 0.5 mol, Cu-In bismuth Due to the shortage of metal nanoparticles, it is difficult to form a p-type CIGS light-absorbing layer thin film, which is not desirable because of poor performance.

On the other hand, in some cases, the ink composition may further include an additive.

The additive may, for example, comprise a dispersant, a surfactant, a polymer, a binder, a crosslinker, an emulsifier, a defoamer, a desiccant, a filler, an extender, a thickener, a film conditioning agent, an antioxidant, a flow agent, Polyvinylpyrrolidone (PVP), polyvinyl alcohol, Anti-terra 204, Anti-terra 205, and the like can be used. Ethyl cellulose, and DISPERS BYK 110 (DispersBYK 110).

On the other hand, the present invention provides a method for producing a thin film using the ink composition for forming a light absorbing layer.

The method for producing a thin film according to the present invention comprises:

(i) a metal chalcogenide of crystalline particles containing group III elements of indium (In) and gallium (Ga) and at least one group VI element selected from the group consisting of sulfur (S) and selenium (Se) A process for preparing an ink composition by mixing nanoparticles and Cu-In bimetallic metal nanoparticle particles together with a solvent;

(ii) coating the ink composition on a substrate; And

(iii) drying and then heat treating the ink composition coated on the substrate;

. &Lt; / RTI &gt;

In one specific example, the solvent of the above process (i) can be used without particular limitation as long as it is a general organic solvent, and examples thereof include alkanes, alkenes, alkynes, aromatics, But are not limited to, ketones, nitriles, ethers, esters, organic halides, alcohols, amines, thiols, Organic solvents selected from carboxylic acids, phosphines, phosphites, phosphates, sulfoxides, and amides may be used alone or in combination with one or more of these organic solvents. May be used in a mixed form.

Specifically, the alcohol-based solvent is selected from the group consisting of ethanol, 1-propanol, 2-propanol, 1-pentanol, 2- Hexanol, 2-hexanol, 3-hexanol, heptanol, octanol, EG (ethylene glycol), DEGMEE (diethylene glycol) monoethyl ether (EGMME), ethylene glycol monoethyl ether (EGMEE), ethylene glycol dimethyl ether (EGDEE), ethylene glycol monopropyl ether (EGMPE), ethylene glycol monobutyl ether 2-methyl-1-propanol, cyclopentanol, cyclohexanol, propylene glycol propyl ether (PGPE), DEGDME (diethylene glycol dimethyl ether), 1 (1,3-propanediol), 1,4-BD (1,4-butanediol), 1,3-BD (1,3-butanediol) Alpha-terpineol, DEG (diethylene glycol), glycerol, 2-ethylamino ethanol, (2-amino-2-methyl-1-propanol), 2- (methylamino) ethanol, 2- It can be used every day.

The amine-based solvent is selected from the group consisting of triethylamine, dibutylamine, dipropylamine, butylamine, ethanolamine, DETA (diethylenetriamine), TETA (triethylenetetraine) Triethanolamine, 2-aminoethyl piperazine, 2-hydroxyethyl piperazine, dibutylamine, and tris (2-aminoethyl) amine (tris (2-aminoethyl) amine).

The thiol-based solvent may be one or more kinds of mixed solvents selected from among 1,2-ethanedithiol, pentanethiol, hexanethiol, and mercaptoethanol.

The alkane solvent may be one or more kinds of mixed solvents selected from the group consisting of hexane, heptane and octane.

The aromatic solvent may be one or more kinds of mixed solvents selected from the group consisting of toluene, xylene, nitrobenzene, and pyridine.

The organic halide solvent may be at least one compound selected from the group consisting of chloroform, methylene chloride, tetrachloromethane, dichloroethane, and chlorobenzene. have.

The nitrile solvent may be acetonitrile.

The ketone solvent may be one or more kinds of mixed solvents selected from the group consisting of acetone, cyclohexanone, cyclopentanone, and acetyl acetone.

The ethers solvent may be one or more daily for mixing selected from ethyl ether, tetrahydrofurane, and 1,4-dioxane.

The sulfoxides solvent may be one or more daily for mixing selected from dimethyl sulfoxide (DMSO) and sulfolane.

The amide solvent may be one or more kinds of mixed solvents selected from DMF (dimethyl formamide), and NMP (n-methyl-2-pyrrolidone).

The ester solvent may be one or more daily for mixing selected from ethyl lactate, r-butyrolactone, and ethyl acetoacetate.

The carboxylic acid solvent may be selected from the group consisting of propionic acid, hexanoic acid, meso-2,3-dimercaptosuccinic acid, thiolactic acid ), And thioglycolic acid.

However, the solvents may be but one example.

The method of forming the coating layer of the process (ii) may be performed by, for example, a wet coating, a spray coating, a spin coating, a doctor blade coating, a contact printing, an upper feed reverse printing, feed reverse printing, nozzle feed reverse printing, gravure printing, micro gravure printing, reverse micro gravure printing, roller coating, slot die coating, Capillary coating, inkjet printing, jet deposition, spray deposition, and the like.

The heat treatment in step (iii) may be performed at a temperature in the range of 300 to 900 degrees Celsius.

On the other hand, in order to produce a thin film of a solar cell with a higher density, a selenization process may be selectively included, and the selenification process may be performed by various methods.

In the first example, in step (i), S and / or Se are dispersed in a solvent in the form of particles together with one or more metal chalcogenide nanoparticles and Cu-In bimetallic metal nanoparticle particles to prepare an ink, And through the heat treatment in the step (iii).

In the second example, the heat treatment of the above process (iii) can be accomplished by carrying out the process under the presence of S or Se.

Specifically, the condition in which the S or Se element is present may be supplied in the form of a gas of H ₂ S or H ₂ Se, or by heating Se or S to supply the gas.

In the third example, step (iii) may be performed after stacking S or Se after step (ii). Specifically, the lamination may be performed by a solution process or may be performed by a deposition method.

The present invention also provides a thin film produced by the above method.

The thin film may have a thickness within the range of 0.5 탆 to 3.0 탆, and more specifically, the thickness of the thin film may be 0.5 탆 to 2.5 탆.

When the thickness of the thin film is less than 0.5 탆, the density and quantity of the light absorbing layer are not sufficient and the desired photoelectric efficiency can not be obtained. When the thickness of the thin film exceeds 3.0 탆, The probability of recombination is increased, resulting in a reduction in efficiency.

Furthermore, the present invention provides a thin film solar cell manufactured using the thin film.

A method of manufacturing a thin film solar cell is already known in the art and a description thereof will be omitted herein.

As described above, the metal chalcogenide nanoparticles according to the present invention are characterized in that Group III elements of indium (In) and gallium (Ga) and one group selected from the group consisting of sulfur (S) and selenium (Se) The present inventors have found that the crystalline particles containing all of the VI group elements described above significantly reduce the particle size nonuniformity in the inks generated by using the conventional amorphous particles of several micrometers and increase the composition uniformity and dispersibility of the particles, A light absorption layer having a uniform composition and an increased film density can be formed, and a thin film can be manufactured without further mixing of gallium (Ga) -containing particles, so that the process can be further simplified.

1 is an electron microscope (SEM) photograph of indium gallium sulfide nanoparticles formed in Example 1;
2 is an electron microscope (SEM) photograph of an ink composition prepared using the nanoparticles of Example 1 according to Experimental Example 1;
3 is an electron microscope (SEM) photograph of the ink composition prepared using the nanoparticles of Comparative Example 1 according to Experimental Example 1. Fig.

Hereinafter, the present invention will be described with reference to Examples. However, the following Examples are intended to illustrate the present invention, and the scope of the present invention is not limited thereto.

&Lt; Preparation Example 1 &

Synthesis of Cu-In Particles

To the aqueous solution containing 60 mmol of NaBH ₄ , a mixed aqueous solution containing 12 mmol of CuCl _2, 10 mmol of InCl ₂ and 50 mmol of trisodium citrate was added dropwise over 1 hour, and then stirred for 24 hours And the formed particles were purified by centrifugation to prepare bimetallic nanoparticles of Cu ₂ In.

&Lt; Example 1 >

1.7 mmol of indium acetic acid (In (OAc) ₃ ) and 1.7 mmol of gallium nitrate aqueous solution (Ga (NO ₃ ) ₃ ) were dissolved in 50 ml of oleylamine and heated to 300 ° C. To this solution, 20 mmol of S (sulfur) powder was dissolved in 20 ml of oleylamine, and the mixture was reacted under nitrogen atmosphere for 18 hours to prepare InGaS ₃ nanoparticles. An SEM photograph of the formed particles is shown in Fig.

&Lt; Comparative Example 1 &

InGaS ₃ nanoparticles were prepared by dissolving 2.5 mmol of indium chloride aqueous solution, 2.5 mmol of gallium iodide solution and 10 mmol of Na ₂ S in 50 ml of distilled water, heating them to 150 ° C. and reacting for 2 hours.

<Experimental Example 1>

The nanoparticles prepared in Example 1 and Cu ₂ In formed in Production Example 1 were dispersed in a solvent composed of an alcohol-based mixed solvent at a concentration of 20% and mixed with beads for 3 days to prepare an ink composition. Electron microscopic (SEM) photographs of the ink composition are shown in FIG.

The nanoparticles prepared in Comparative Example 1 and Cu ₂ In formed in Preparation Example 1 were dispersed in a solvent composed of an alcohol-based mixed solvent at a concentration of 20% and mixed with beads for 3 days to prepare an ink composition. Electron microscopic (SEM) photographs of the ink composition are shown in FIG.

2 and 3, the ink composition prepared using the InGaS ₃ nanoparticles prepared in Example 1 was uniformly mixed so that the individual particles were dispersed as a whole, while the InGaS ₃ nanoparticles prepared in Comparative Example 1 It can be confirmed that the ink composition prepared using the nanoparticles is dispersed very heterogeneously due to the difference in size of the particles contained therein.

&Lt; Example 2 >

The nanoparticles formed in Example 1 and Cu ₂ In formed in Production Example 1 were dispersed in a solvent composed of an alcohol-based mixed solvent at a concentration of 13% and mixed with beads for 3 days to prepare an ink composition. The ink composition was coated on a substrate obtained by vapor-depositing Mo on a glass substrate to prepare a coating film for CIGS thin film production. After drying at 250 ° C, CIGS thin film was obtained by heat treatment at 575 ° C for 10 minutes under Se atmosphere.

&Lt; Comparative Example 2 &

The nanoparticles formed in Comparative Example 1 and Cu ₂ In formed in Production Example 1 were dispersed in a solvent composed of an alcohol-based mixed solvent at a concentration of 13% and mixed with beads for 3 days to prepare an ink composition. The ink composition was coated on a substrate obtained by vapor-depositing Mo on a glass substrate to prepare a coating film for CIGS thin film production. After drying at 250 ° C, CIGS thin film was obtained by heat treatment at 575 ° C for 10 minutes under Se atmosphere.

<Experimental Example 2>

Manufacture of Thin Film Solar Cell

CdS buffer layers were prepared by CBD method on each of the CI (G) thin films obtained in Example 2 and Comparative Example 2, and ZnO and AlZnO were sequentially deposited, and then the Al electrodes were grown using an e-beam The photovoltaic efficiency of the prepared CIGS thin film solar cells was measured and the results are summarized in Table 1 below.

J _sc (mA / cm ² ) V _oc (V) FF (%) Photoelectric efficiency (%) Example 2 31.47 0.412 40.00 5.19 Comparative Example 2 29.17 0.399 26.37 3.07

J _sc , a variable for determining the efficiency of the solar cell shown in Table 1, means the current density, V _oc means the open circuit voltage measured at the zero output current, and the photoelectric efficiency is the energy of the light incident on the solar panel (Fill factor) means a value obtained by dividing the product of the current density at the maximum power point and the voltage value by the product of Voc and J _sc .

As can be seen from Table 1, when the metal chalcogenide nanoparticles were used to form the light absorbing layer according to the present invention, it was confirmed that the current density and photoelectric efficiency were high.

This is because, as shown in Figs. 2 and 3, when the light absorbing layer thin film is produced due to the difference in the uniformity of the particles in the ink composition, it affects the film density and the degree of pore formation and uniformity of the composition to be.

Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims (25)

Wherein the metal chalcogenide nanoparticles are composed of Group III elements of indium (In) and gallium (Ga), sulfur (S) and selenium (Se) &Lt; / RTI &gt; wherein the metal nanoparticles are crystalline particles containing at least one Group VI element selected from the group consisting of metal nanoparticles. The metal chalcogenide nanoparticles according to claim 1, wherein the metal chalcogenide nanoparticles are represented by the following chemical formula 1:
(In _1-x Ga _x ) _m (S _1-y Se _y ) _n (1)
In this formula,
0 <x <1, 0? Y? 1, 0 <n / m? The metal chalcogenide nanoparticles according to claim 2, wherein the content ratio of S to Se (n / m) relative to the content of In and Ga in the chemical formula 1 is 1? N / m? 8. The metal chalcogenide nanoparticles of claim 1, wherein the metal chalcogenide nanoparticles have a particle size of less than 100 nanometers. The metal chalcogenide nanoparticles according to claim 4, wherein the metal chalcogenide nanoparticles have a particle diameter of 30 nanometers to 90 nanometers. The metal chalcogenide nanoparticles according to claim 1, wherein the metal chalcogenide nanoparticles are synthesized in an amine-based solvent. A method for producing metal chalcogenide nanoparticles forming a light absorbing layer of a solar cell,
(i) at least one group VI source selected from the group consisting of sulfur (S), selenium (Se), or compounds including sulfur (S) and selenium (Se) is dispersed in an amine- ;
(ii) an amine-based solvent containing an indium (In) salt and a gallium (Ga) salt to prepare a second solution;
(iii) heating the second solution, and then mixing the first solution with the second solution;
(iv) synthesizing nanoparticles by the reaction of the mixture and purifying the nanoparticles;
Wherein the method comprises the steps of: The method of claim 7, wherein the amine-based solvent is at least one selected from the group consisting of oleylamine, octylamine, ethanolamine, isopropanolamine, N-butylamine, isobutylamine wherein the metal is at least one selected from the group consisting of isobutylamine, dimethanolamine, diethanolamine, dipropanolamine, dibutylamine, and benzylamine. Method for producing chalcogenide nanoparticles. The method of claim 7, VI group source in the process (i) is _{Se, Na 2 Se, K 2} Se, CaSe, (CH 3) 2 Se, SeO 2, SeCl 4, H 2 SeO 3, H 2 SeO 4 , Na ₂ S, K ₂ S, CaS, (CH ₃ ) ₂ S, H ₂ SO ₄ , S, Na ₂ S ₂ O ₃ , NH ₂ SO ₃ H and their hydrates, thiourea, Wherein the metal chalcogenide nanoparticles are at least one selected from the group consisting of thioacetamide, and selenourea. The method of claim 7, wherein the salt of step (ii) is selected from the group consisting of chloride, bromide, iodide, nitrate, nitrite, sulfate, acetate Wherein the metal chalcogenide nanoparticles are at least one selected from the group consisting of sulfates, sulfates, acetylacetoates, and hydroxides. [8] The method of claim 7, wherein the heating in step (iii) is performed at a temperature ranging from 150 to 400 [deg.] C. 8. The method of claim 7, wherein the Group VI source is included in an amount of 1 to 5 moles per mole of indium (In) and gallium (Ga). 8. The method of claim 7, wherein the synthesized nanoparticles are crystalline particles having an average particle diameter of 30 nm to 90 nm. An ink composition for producing a light absorbing layer, comprising the metal chalcogenide nanoparticles according to claim 1. 15. The ink composition of claim 14, wherein the ink composition further comprises Cu-In bimetallic metal nanoparticles. 16. The method of claim 15, wherein the Cu-In bimetalic metal nanoparticles are at least one selected from the group consisting of Cu ₁₁ In ₉ , Cu ₁₆ In ₄ , Cu ₂ In, Cu ₇ In ₄ , and Cu ₄ In. By weight based on the total weight of the ink composition. 16. The ink composition according to claim 15, wherein the Cu-In bimetallic metal nanoparticles and the metal chalcogenide nanoparticles are mixed in a range of 0.5 < Cu / (In + Ga) < 15. The ink composition according to claim 14, wherein the ink composition further comprises an additive. 19. The method of claim 18, wherein the additive is selected from the group consisting of polyvinylpyrrolidone (PVP), polyvinyl alcohol, Anti-terra 204, Anti-terra 205, ethyl cellulose, Disperse BYK110 (DispersBYK110), and the like. A method for producing a thin film using the ink composition for producing a light absorbing layer according to claim 14,
(i) a metal chalcogenide of crystalline particles containing group III elements of indium (In) and gallium (Ga) and at least one group VI element selected from the group consisting of sulfur (S) and selenium (Se) A process for preparing an ink composition by mixing nanoparticles and Cu-In bimetallic metal nanoparticle particles together with a solvent;
(ii) coating the ink composition on a substrate; And
(iii) drying and then heat treating the ink composition coated on the substrate;
Wherein the thin film is formed on the substrate. 21. The method of claim 20, wherein the solvent of step (i) is selected from the group consisting of alkanes, alkenes, alkynes, aromatics, ketons, nitriles, Ethers, esters, organic halides, alcohols, amines, thiols, carboxylic acids, hydrogenated amines, and the like. wherein the organic solvent is at least one organic solvent selected from the group consisting of phosphines, phosphates, sulfoxides, and amides. 21. The method of claim 20, wherein the coating of step (ii) is wet coating, spray coating, spin coating, doctor blade coating, contact printing, top reverse feed printing, Printing, nozzle feed reverse printing, gravure printing, micro gravure printing, reverse micro gravure printing, roller coating, slot die coating, capillary coating, Wherein the film is formed by ink jet printing, jet deposition, or spray deposition. 21. The method of claim 20, wherein the heat treatment in step (iii) is performed at a temperature in the range of 300 to 900 degrees. A thin film produced by the process according to claim 20. A thin film solar cell produced using the thin film according to claim 24.

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