KR101751130B1 - Precursor for Manufacturing Light Absorbing Layer of Solar Cell and Method for Manufacturing the Same - Google Patents

Abstract

The present invention relates to a precursor for the production of a light absorbing layer of a solar cell, which comprises (a) a first phase consisting of a copper (Cu) -stin (Sn) bimetallic metal, A first phase consisting of a copper (Cu) -stin (Sn) bimetallic metal and a second phase consisting of a zinc (Zn) -containing chalcogenide, An agglomerated composite comprising a phase and a third phase consisting of copper (Cu) -containing chalcogenide; Or (b) a core made of copper (Sn) bimetallic metal nanoparticles, a chalcogenide containing zinc (Zn) or a chalcogenide containing zinc (Zn) Nanoparticles of a core-shell structure comprising a shell of cogeneride; Or (c) a mixture thereof. The present invention also relates to a method for producing the precursor.

Description

TECHNICAL FIELD [0001] The present invention relates to a precursor for manufacturing a solar cell light absorbing layer and a method for manufacturing the same,

This application claims the benefit of priority based on Korean Patent Application No. 10-2014-0152663 dated November 21, 2014, and the entire contents of the Korean patent application are incorporated herein by reference.

The present invention relates to a precursor for the production of a solar cell light absorbing layer and a method of manufacturing the same.

Since the early days of development, solar cells have been fabricated using silicon (Si) as a light absorbing layer and semiconductor material, which are expensive manufacturing processes. (Cu, In, Ga) (S, Se) ₂ ) and low cost CIGS (copper-indium-gallium-sulfo-selenide) as a structure of thin film solar cell to manufacture solar cell more economically industrially Products using the same light absorbing materials have been developed. The CIGS-based solar cell typically comprises a back electrode layer, an n-type junction, and a p-type light absorbing layer. The solar cell having the CIGS layer described above has a power conversion efficiency exceeding 19%. However, despite the potential for CIGS-based thin film solar cells, due to the inadequate cost and supply of indium (In), it has become a major obstacle to the wide use and applicability of thin film solar cells using the CIGS type light absorbing layer. It is urgent to develop solar cells that use low-cost general-purpose elements such as -free or In-less.

Therefore, in recent years, attention has been paid to CZTS (Cu ₂ ZnSn (S, Se) ₄ ) -based solar cells containing copper, zinc, tin, sulfur or selenium as an ultra low cost metal element as an alternative to the CIGS- have. The CZTS has a direct band gap of about 1.0 to 1.5 eV and an absorption coefficient of 10 ⁴ cm ^-1 or more, and has an advantage of using Sn and Zn, which are relatively rich in reserves and low in cost.

Although the first CZTS hetero-junction PV cell was reported in 1996, the CZTS-based solar cell technology lags behind the CIGS solar cell technology, and the photoelectric efficiency of the CZTS cell is less than 10% It is still in short supply. The thin films of CZTS can be formed by sputtering, hybrid sputtering, pulse laser deposition, spray pyrolysis, electrodeposition / thermal sulfurization, E-beam Cu / Zn / Sn / Thermal < / RTI > sulfation, and sol-gel.

On the other hand, PCT / US / 2010-035792 discloses a thin film formed on a substrate by using an ink containing CZTS / Se nanoparticles. In general, CZTS / Se nanoparticles are used to form a CZTS thin film It is difficult to increase the size of crystals in the process of forming a thin film thereafter. When each grain is small, the boundary is enlarged, and because of the loss of electrons generated at the boundary surface Efficiency is inevitable.

Therefore, the nanoparticles used in the thin film should include Cu, Zn, and Sn but not CZTS crystals. If only metal nanoparticles composed of a single metal element are used, the metal nanoparticles are easily oxidized, And a process for removing oxides using Se and a high temperature is required. When the chalcogenide containing each metal is synthesized and mixed in the ink manufacturing step or mixed with metal nanoparticles, a metal And the intermixing between the metal nanoparticles having different phases is insufficient to form a secondary phase in the thin film.

Accordingly, it is an object of the present invention to provide a thin film solar cell capable of forming a highly efficient light absorbing layer having a stable and sufficiently stable oxidation group VI and having a more uniform composition as a whole and minimizing the formation of a secondary phase in the thin film, There is a high need for technology.

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.

(A) a first phase made of a copper (Cu) -stin (Sn) bimetallic metal and a second phase made of a zinc (Zn) -containing metal. The present inventors have conducted intensive research and various experiments, A first phase consisting of a copper (Cu) -stannard (Sn) bimetallic metal and a second phase consisting of a zinc (Zn) -containing chalcogenide A flocculated composite comprising a second phase and a third phase consisting of copper (Cu) -containing chalcogenide; Or (b) a core made of copper (Sn) bimetallic metal nanoparticles, a chalcogenide containing zinc (Zn) or a chalcogenide containing zinc (Zn) Nanoparticles of a core-shell structure comprising a shell of cogeneride; Or c) a mixture thereof. When a thin film is prepared by using the precursor, a homogeneous composition as a whole is minimized to minimize the formation of a secondary phase in the thin film, And the content of VI group element in the final thin film is increased by including S or Se in the precursor itself, and it has been found that the present invention has been completed.

Therefore, the precursor for the production of the light absorbing layer of the solar cell according to the present invention,

(a) a first phase consisting of a copper (Cu) -stin (Sn) bimetallic metal and a second phase consisting of a zinc-containing chalcogenide, A second phase consisting of zinc (Zn) -containing chalcogenide, a copper (Cu) -containing chalcogenide phase, and a second phase consisting of a bismuth- An agglomerated complex comprising a third phase formed; or

(b) a core made of copper (Cu) -stin (Sn) bimetallic metal nanoparticles, a chalcogenide containing zinc or a chalcogenide containing zinc and a chalcogenide containing copper Nanoparticles of a core-shell structure comprising a shell of a nide; or

(c) a mixture thereof;

.

More specifically, a precursor for the production of a light absorbing layer of a solar cell according to the present invention comprises a core made of copper (Cu) -stin (Sn) bimetallic metal nanoparticles and a core made of zinc (Zn) -containing chalcogenide or zinc Zn) -containing chalcogenide, and a copper (Cu) -containing chalcogenide.

In the case of the core-shell structure nanoparticles, copper (Cu), tin (Sn) and zinc (Zn) metals exist in a more uniformly mixed state, since the core made of a bimetallic metal is protected by a shell composed of zinc (Zn) -containing chalcogenide, it is stable to oxidation, and the formation of oxides on the surface of the particles is minimized, . Further, the inclusion of copper (Cu) -containing chalcogenide in the shell not only increases the uniformity of elemental distribution in the particle but also increases the uniformity of the distribution of Cu / Sn contained in the core By lowering the ratio, formation of the secondary phase during the heat treatment reaction can be further minimized, which is preferable.

Specifically, when the shell contains no Cu-containing chalcogenide, the ratio of Cu / Sn contained in the core is 1.7 or more to 2.1 or less based on the amount of Cu contained in the whole particles, (Cu) contained in the core is contained in the core, the ratio of Cu / Sn contained in the core is reduced to about 1.2 or more to about 1.6 or less based on the amount of Cu contained in the whole particles. The amount of Cu that is insufficient at this time can be supplemented by adjusting the content of copper (Cu) -containing chalcogenide in the shell.

In one specific example, the Cu-Sn bimetallic metal means an alloy form of Cu and Sn, and is not limited as long as it has a Cu / Sn ratio (based on the molar ratio) of 1 or more. For example, CuSn, Cu ₃ Sn , Cu _3.02 Sn _0.98 , Cu ₁₀ Sn ₃ , Cu _6.26 Sn ₅ , Cu ₆ Sn ₅ , and Cu ₄₁ Sn ₁₁ .

In one specific example, 'chalcogenide' refers to a material comprising a Group VI element such as sulfur (S) and / or selenium (Se), wherein the zinc-containing chalcogenide ZnS and ZnSe, and the copper (Cu) -containing chalcogenide may be at least one selected from the group consisting of Cu _x S _y and Cu _x Se _y (where 0 <x≤1, 0 <y≤2) And may be CuS or CuSe in detail.

Therefore, in the shells of nanoparticles of the second phase and the third phase or core-shell structure of the aggregated complex, Cu / Zn (Zn) contained in the chalcogenide containing zinc (Zn) and chalcogenide containing copper (Based on the molar ratio) may be varied according to the ratio of Cu / Sn in the core portion, but may be 0? Cu / Zn? 20 in detail, and more specifically 0? Cu / Zn? .

In this case, the ratio of Cu / Zn is 0 when the coagulated complex does not contain the third phase or when the shell of the core-shell nanoparticles does not contain copper (Cu) -containing chalcogenide means, and if the composition of the metal falls outside this range, such as so CZTS (e) is of an excessive difference from the composition ratio of the level of formation this ZnS, ZnSe, CuS, CuSe, and / or Cu ₂ SnS (e) of The secondary phase is excessively formed to deteriorate photoelectric characteristics, which is not preferable.

The term &quot; aggregate phase composite &quot; used in the present invention means that the particles including the first phase, the particles including the second phase and the particles including the third phase are uniformly aggregated Means a form in which one unit is formed.

Thus, the first phase, the second phase, and the third phase of the aggregated complex may be independently present in one complex, and the morphology of the complex is not limited and may vary, but in one specific example , And the first, second, and third phases may be randomly distributed as respective regions.

The particle size of such a flocculated composite is larger than the particle size of the particles formed by the respective phases since the particles formed by the respective phases are agglomerated as described above. In one specific example, the particle size of 5 to 500 nanometers .

On the other hand, as another embodiment of the precursor for producing a light absorbing layer of the present invention, the nanoparticles of the core-shell structure are prepared by mixing Cu-Sn bimetallic metal nanoparticles with chalcogenide containing zinc (Zn) Nitrogen and copper (Cu) -containing chalcogenide form a single particle. The particle size of the nanoparticles of the core-shell structure may be from 2 nanometers to 200 nanometers.

It has been confirmed by the inventors of the present application that, in the case of producing a thin film by using nanoparticles of such a flocculated composite or core-shell structure as a precursor, the metal and chalcogenide elements are already uniformly formed When the particles containing the respective elements are separately synthesized and mixed, for example, a mixture of Cu-Sn bimetallic metal nanoparticles and zinc (Zn) chalcogenide nanoparticles or zinc (Zn) (Cu) chalcogenide, zinc (Zn) chalcogenide, and tin (Sn) chalcogenide nanoparticles were synthesized and mixed, respectively, by mixing and synthesizing chalcogenides and chalcogenides containing copper In this case, the uniformity of the contrast composition can be improved, and thus a CZTS thin film having a minimized formation of the secondary phase can be obtained.

At this time, the nanoparticles of the aggregated phase composite or the core-shell structure preferably have a metal composition of 0.5? Cu / (Zn + Sn)? 1.5 and 0.5? Zn / Sn? 2, and more specifically, the range of 0.7? Cu / (Zn + Sn)? 1.2 and 0.7? Zn / Sn? 1.8 can be satisfied.

When the composition of the metal is out of the above range, a large amount of secondary phase is formed and the photoelectric efficiency is reduced as it is present as an impurity, which is not preferable.

The composition ratio of the chalcogenide element in the zinc (Zn) -containing chalcogenide and the copper (Cu) -containing chalcogenide may be 0.5 to 3 mol based on 1 mol of zinc (Zn) or copper (Cu).

If the amount is less than 0.5 mole, it is impossible to provide a sufficient amount of the Group VI element, so that a film partially lacking the Group VI element may be formed. If the amount of the Group VI element is more than 3 mol, It is unfavorable because it causes non-uniformity of film growth due to one distribution or excessive formation of voids in the final thin film due to evaporation of the Group VI source in the heat treatment process for producing the thin film.

Such a precursor for producing a light absorbing layer,

(i) preparing a first solution containing a reducing agent and a second solution containing a copper (Cu) salt and a tin (Sn) salt;

(ii) synthesizing copper (Cu) -stin (Sn) bismuth metal nanoparticles by mixing and reacting the first solution and the second solution; And

(iii) mixing and reacting a zinc (Zn) -ligand complex with a solution of the Cu-Sn bimetallic metal nanoparticles dispersed in the step (ii);

. &Lt; / RTI &gt;

Further, after the step (iii), a step of adding a copper (Cu) salt to the reactant in the step (iii) to synthesize a precursor for the preparation of a light absorbing layer through a Zn-Cu substitution reaction and then refining have.

As described above, when the zinc (Zn) -ligand complex is used, the zinc (Zn) -containing chalcogenide phase is introduced without the fourth solution containing the zinc (Zn) salt and the third solution containing the group VI source So that it is not only uniform in composition as a whole but also is economically efficient.

In one specific example, the ligand contained in the ligand conjugate is not limited as long as it can be used as a source of a group VI element, but may be, for example, one or more selected from the following.

In the zinc (Zn) -ligand complex, the number of ligands bound to Zn is not particularly limited, but may be, for example, 1 to 4, and the number of ligands bound to Zn may be one or more.

Further, the precursor for the production of a light absorbing layer,

(i) preparing a first solution containing a reducing agent and a second solution containing a copper (Cu) salt and a tin (Sn) salt;

(ii) synthesizing copper (Cu) -stin (Sn) bimetallic metal nanoparticles by mixing and reacting the first solution and the second solution;

(iii) a third solution comprising at least one Group VI source selected from the group consisting of compounds comprising sulfur (S), selenium (Se), sulfur (S), and selenium (Se) , A zinc (Zn) salt; And

(iv) mixing and reacting the third solution and the fourth solution in a solution in which the Cu-Sn bimetalic metal nanoparticles of the step (ii) are dispersed to synthesize a precursor for the preparation of a light absorption layer, and then purifying the precursor;

. &Lt; / RTI &gt;

Further, after the step (iv), a step of adding a copper (Cu) salt to the reactant in the step (iv) to synthesize a precursor for the preparation of a light absorbing layer through a Zn-Cu substitution reaction and then refining have.

Here, the Zn-Cu substitution reaction is a reaction in which a part of the zinc (Zn) -containing chalcogenide is substituted with copper (Cu) -containing chalcogenide by a reduction potential difference between zinc (Zn) and copper (Cu).

As a result of the substitution reaction, Cu is contained in the third phase or shell of the precursor for preparing a light absorbing layer. As described above, the ratio of Cu / Sn contained in the core is lowered based on the amount of Cu contained in the whole particles. The effect of further suppressing the formation of the secondary phase can be exhibited.

Since the precursor thus prepared is continuously mixed with the first solution to the fourth solution, the Cu-Sn bimetallic metal phase and the zinc (Zn) -containing chalcogenide phase are not synthesized as separate independent particles, (A) a first phase consisting of a copper (Cu) -stin (Sn) bimetallic metal and a second phase consisting of a zinc-containing chalcogenide, A first phase consisting of a copper (Cu) -stin (Sn) bimetallic metal, a second phase consisting of a zinc-containing chalcogenide and a second phase consisting of a copper- An agglomerated complex comprising a third phase consisting essentially of NaI; Or (b) a core made of copper (Sn) bimetallic metal nanoparticles, a chalcogenide containing zinc (Zn) or a chalcogenide containing zinc (Zn) Nanoparticles of a core-shell structure comprising a shell of cogeneride; Or (c) a mixture thereof.

The composition may be controlled by reaction conditions such as the reaction temperature, the reaction concentration, the reaction time, and the type of the capping agent, and the uniformity of the composition and particle size of the nanoparticles of the aggregated phase composite or core- , When the first solution and the second solution are mixed and when the zinc (Zn) -ligand complex or the third solution and the fourth solution are mixed in a solution in which Cu-Sn bimetalic metal nanoparticles are dispersed And when the Zn-Cu substitution reaction is carried out, the equivalence ratio of the solutions, the content of the copper (Cu) salt or ligand complex, the dropping rate, the stirring speed, the reaction temperature after mixing, And so on.

On the other hand, when mixing the second solution into the first solution to prepare the mixture, the total amount of the salt and the mixing ratio of the reducing agent may be, for example, 1: 1 to 1:20 in terms of molar ratio.

When the content of the reducing agent is too small in the salt, the reduction of the metal salt does not sufficiently take place, so that it is difficult to obtain only the metal nanoparticles of an extremely small size or a small amount of bimetallic type or to obtain particles of the desired element ratio. Also, when the content of the reducing agent is more than 20 times the amount of the salt, it is difficult to remove the reducing agent and the by-product in the purification process.

In one specific example, the reducing agent contained in the first solution may be an organic reducing agent and / or an inorganic reducing agent, and specifically, LiBH ₄ , NaBH ₄ , _{KBH 4, Ca (BH 4)} 2, Mg (BH 4) 2, LiB (Et) 3 H, NaBH 3 (CN), NaBH (OAc) 3, N 2 H 4, ascorbic acid (ascorbic acid) and triethanolamine triethanolamine, and the like.

In one specific example, the solvents of the first to fourth solutions include, but are not limited to, water, alcohols, diethylene glycol, oleylamine, ethyleneglycol, triethylene glycol the solvent may be at least one selected from the group consisting of triethylene glycol, dimethyl sulfoxide, dimethyl formamide and N-methyl-2-pyrrolidone (NMP) , Methanol having 1 to 8 carbon atoms, ethanol, propanol, butanol, pentanol, hexanol, heptanol, and octanol.

In one specific example, the salts of copper (Cu) salts, tin (Sn) salts and zinc (Zn) salts are, independently of each other, fluoride, chloride, bromide, iodide (iodide), nitrate, nitrite, sulfate, acetate, citrate, sulfite, acetylacetoate, acrylate, Cyanide, phosphate and hydroxide. In the case of tin (Sn) salts, the divalent and tetravalent salts are not limited and may be used in all cases. It is possible.

In one specific example, the Group VI source is selected from the group consisting of Se, Na ₂ Se, K ₂ Se, CaSe, (CH ₃ ) ₂ Se, SeO ₂ , SeS ₂ , Se ₂ S ₆ , Se ₂ Cl ₂ , Se ₂ Br ₂ , SeCl _4, SeBr _4, (CH ₃ ) ₂ S, H ₂ SO ₄ , Na ₂ S ₂ O ₃ , and NH ₂ SO ₃ H, or a mixture of these compounds, such as SeCO ₂ , H ₂ SeO ₃ , H ₂ SeO ₄ , S, Na ₂ S, K ₂ S, (S) of a compound of formula (I) or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier, such as HSCH ₂ COOH, thiolactic acid, mercaptoethanol, aminoheptanethiol, thiourea, thioacetamide, and selenourea And may be one or more selected from the group consisting of

Meanwhile, at least one of the first solution to the fourth solution may further include a capping agent. Of course, if necessary, the capping agent may be added separately during the manufacturing process.

Since the capping agent not only controls the size and particle size of the metal nanoparticles and the precursor for preparing a light absorbing layer synthesized by being included in the solution process, but also contains atoms such as N, O, S and the like, electrons can easily bind to the surface of the metal nanoparticles to surround the surface, thereby preventing oxidation of the metal nanoparticles.

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) Poly (vinyl pyrrolidone) (PVP), sodium citrate, trisodium citrate, disodium citrate, glue, Sodium gluconate, sodium ascorbate, sorbitol, triethyl phosphate, ethylene diamine, propylene diamine, ethanedithiol (1,2, ethanethiol, aminoethanethiol, mercaptoethanol, mercaptopropionic acid (MPA), polyvinyl alcohol (PVA), and ethylcellulose It may be at least one selected from the group consisting of (ethyl cellulose).

The content of the capping agent may be appropriately included in the solvent, for example, 20 moles or less to 1 mole of the total metal salt.

If the content of the capping agent is more than 20 times, the purification process of the precursor may be difficult and the purity may be lowered.

The present invention also provides an ink composition for producing a light absorbing layer in which the precursor for the production of a light absorbing layer is dispersed in a solvent, and a method for producing a thin film using the precursor for producing the light absorbing layer.

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

(i) a first phase consisting of (a) a copper (Cu) -stannard (Sn) bimetallic metal and a second phase consisting of a zinc-containing chalcogenide , A first phase consisting of a copper (Cu) -stin (Sn) bimetallic metal, a second phase consisting of a zinc-containing chalcogenide and a copper- A flocculant complex comprising a third phase consisting of cogeneride; Or (b) a core made of copper (Sn) bimetallic metal nanoparticles, a chalcogenide containing zinc (Zn) or a chalcogenide containing zinc (Zn) Nanoparticles of a core-shell structure comprising a shell of cogeneride; Or (c) a mixture thereof; a step of dispersing a precursor for preparing a light absorbing layer in a solvent to prepare an ink;

(ii) coating the ink on a substrate on which electrodes are formed; And

(iii) drying the ink coated on the substrate on which the electrode is formed, followed by heat treatment;

.

When a thin film is prepared using the precursor according to the present invention, since the precursor synthesized in a state where the elements are already mixed is used, the formation of the secondary phase having a more uniform composition as a whole is minimized, Due to the addition of an additional VI group element in the heat treatment process of the step (iii) by the first phase or core made of a bimetallic metal, the volume of the precursor increases, so that a high density optical absorption layer can be grown. A high-quality thin film having a high content of VI group elements in the final thin film can be produced.

In one specific example, the solvent of the above-mentioned process (i) is not particularly limited as long as it is a general organic solvent, and examples thereof include alkanes, alkenes, alkynes, aromatics, Ketones, nitriles, ethers, esters, organic halides, alcohols, amines, thiols, kerosene, and the like. Organic solvents selected from carboxylic acids, phosphines, phosphites, phosphates, sulfoxides, and amides may be used alone or in combination with one or more of them And one or more selected 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.

In some cases, it may be prepared by further adding an additive to the ink of the above-mentioned process (i).

The additive may, for example, comprise a dispersant, a surfactant, a polymer, a binder, a crosslinking agent, 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 (PVA), Anti-terra 204, Anti-terra 205, and the like. ), Ethyl cellulose, and DISPERS BYK110 (DispersBYK110).

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 400 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, it can be achieved by dispersing S and / or Se together with the precursor in the above-mentioned process (i) into a solvent in the form of particles to prepare an ink, and conducting the heat treatment of the process (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 precursor for the manufacture of a light absorbing layer according to the present invention comprises: (a) a first phase made of a copper (Cu) -stin (Sn) bimetallic metal; A first phase consisting of a copper (Cu) -stannard (Sn) bimetallic metal and a second phase consisting of a zinc (Zn) -containing chalcogenide A flocculated composite comprising a second phase and a third phase consisting of copper (Cu) -containing chalcogenide; Or (b) a core made of copper (Sn) bimetallic metal nanoparticles, a chalcogenide containing zinc (Zn) or a chalcogenide containing zinc (Zn) Nanoparticles of a core-shell structure comprising a shell of cogeneride; Or (c) a mixture thereof. When a thin film is prepared using the same, the precursor is synthesized in a state where the elements are already uniformly mixed. Therefore, the formation of the secondary phase is minimized with a more uniform composition throughout the thin film, it is possible to grow a high density optical absorption layer by increasing the volume of the precursor upon addition of a VI group element in the heat treatment process by the first phase or the core made of bimetallic metal, By containing a two-phase or shell, it is possible to produce a high-quality thin film having an increased content of the VI group element in the final thin film.

Particularly, in the case of nanoparticles having a core-shell structure, a core made of a copper (Cu) -stin (Sn) bimetallic metal is used as a chalcogenide containing zinc and a chalcogenide containing copper It is possible to minimize the formation of oxides on the surface of Cu-Sn bimetallic particles constituting the core and thereby to improve the reactivity, and in particular, to provide a zinc-containing chalcogenide particle obtained by substituting Cu for zinc- In the case of particles containing chalcogenide and copper-containing chalcogenide at the same time, when the amount of Cu contained in the whole particles is the same, compared with the case where only the zinc-containing chalcogenide is contained, the ratio of Cu / Sn , The uniformity of the copper element distribution in the particles is increased, and the quality of the thin film can be improved by suppressing the formation of the secondary phase during the heat treatment.

1 is an SEM photograph of a precursor for the production of a light absorbing layer according to Example 1;
2 is an XRD graph of a precursor for the production of a light absorbing layer according to Example 1;
3 is a TEM photograph of a precursor for producing a light absorbing layer according to Example 3;
FIG. 4 is a graph of compositional analysis using a line scan of the TEM photograph of FIG. 3;
5 is a SEM photograph of a precursor for producing a light absorbing layer according to Example 11;
6 is an XRD graph of a precursor for the production of a light absorbing layer according to Example 11;
7 is a TEM photograph of a precursor for producing a light absorbing layer according to Example 11;
FIG. 8 is a graph of compositional analysis using a line scan of the TEM photograph of FIG. 7; FIG.
9 is a line-scan result of the composition of the precursor for the light absorbing layer according to Example 22;
10 is a SEM photograph of a precursor for producing a light absorbing layer according to Example 22;
11 is an XRD graph of a precursor for producing a light absorbing layer according to Example 22;
12 is a SEM photograph of a precursor for the production of a light absorbing layer according to Example 24;
13 is an XRD graph of a precursor for producing a light absorbing layer according to Example 24;
14 is a SEM photograph of the thin film prepared in Example 35;
15 is an XRD graph of the thin film prepared in Example 35;
16 is an SEM photograph of the cross-sectional shape of the thin film produced in Example 37;
17 is a SEM photograph of the thin film prepared in Example 43;
18 is an XRD graph of the thin film prepared in Example 43;
19 is a SEM photograph of the thin film prepared in Example 47;
20 is an XRD graph of the thin film prepared in Example 47;
21 is a SEM photograph of the thin film prepared in Example 48;
22 is an EDX table of the thin film prepared in Example 48;
23 is an SEM photograph of the thin film prepared in Comparative Example 7;
24 is an EDX table of the thin film prepared in Comparative Example 7;
25 is a graph of characteristics obtained from a cell using the thin film of Example 37 according to Experimental Example 1;
26 is a graph of characteristics obtained from a cell using the thin film of Example 48 according to Experimental Example 1;
27 is a graph of characteristics obtained from a cell using the thin film of Comparative Example 7 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; Example 1 >

Tetraethylene glycol mixed solution containing 18 mmol of CuCl ₂ and 10 mmol of SnCl ₂ was slowly added dropwise to a triethylene glycol mixed solution containing 150 mmol of NaBH ₄ and then stirred and reacted for 3 hours to obtain Cu ₆ Sn-bimetallic metal nanoparticles were prepared by mixing Sn ₅ and Cu-rich Cu-Sn (Cu ₄₁ Sn ₁₁ ).

A solution of 5 mmol of zinc nitrate in 50 ml of water was added to a solution of the Cu-Sn bimetallic metal nanoparticles dispersed therein, followed by stirring for 1 hour. A solution of 10 mmol of Na ₂ S in 70 ml of distilled water was added dropwise over 1 hour And reacted for 3 hours to prepare a precursor including nanoparticles of Cu-Sn core ZnS shell structure and a flocculated composite comprising Cu ₆ Sn _5, Cu ₄₁ Sn ₁₁ and ZnS phases.

An electron microscope (SEM) photograph and an XRD graph of the formed precursor are shown in FIGS. 1 and 2. FIG.

Referring to FIGS. 1 and 2, XRD analysis of the particles showed a mixed state of a Cu-Sn bimetallic phase and a ZnS crystal phase in which a Cu ₆ Sn ₅ crystal phase and a Cu-rich Cu-Sn crystal phase were mixed , Cu-Sn Phase and ZnS phase are present as homogeneously distributed aggregate complexes or as nanoparticles of core-shell structure with Cu-Sn coated with ZnS.

&Lt; Example 2 >

150 mmol of NaBH ₄ dissolved in distilled water was slowly added dropwise at 50 ° C to a solution containing 15 mmol of CuCl ₂ and 10 mmol of SnCl _{2. The} mixture was stirred for 1 hour to react Cu ₆ Sn ₅ and Cu-rich Cu Cu-Sn bimetallic metal nanoparticles in which Cu ₃ Sn, Cu ₁₀ Sn ₃ , or Cu ₄₁ Sn ₁₁ are mixed is prepared.

A solution prepared by dissolving 11 mmol of zinc acetate in 50 ml of distilled water was added to a solution of the Cu-Sn bimetallic metal nanoparticles dispersed therein. The mixture was stirred for 30 minutes. A solution prepared by dissolving 20 mmol of Na ₂ S in 100 ml of distilled water was added to the solution, For a period of time to prepare a flocculated complex comprising a Cu-Sn phase and a ZnS phase.

&Lt; Example 3 >

A mixed solution containing 20 mmol of CuCl ₂ and 10 mmol of SnCl ₂ was added dropwise to the DMSO solution containing 150 mmol of NaBH ₄ at 80 ° C over 1 hour and then reacted for 24 hours to react the particles. Cu-Sn bimetallic metal nanoparticles composed of a mixed phase of Cu _6.26 Sn ₅ and Cu ₁₀ Sn ₃ were prepared.

The Cu-Sn bimetallic metal nanoparticles were dispersed in ethanol and then added to a solution of 1 g of polyvinylpyrrolidone in 50 ml of ethanol, followed by stirring for one hour. A 12 mmol solution of zinc acetate dissolved in 100 ml of ethanol was added thereto, followed by stirring for an additional 1 hour. To the solution was slowly added dropwise a solution of 12 mmol of thiourea in 50 ml of ethanol over 1 hour and then heated to 50 ° C. to prepare core-shell structure nanoparticles of Cu-Sn bimetallic particles and ZnS phase. A transmission electron microscope (TEM) photograph of the precursor thus formed and its analysis results are shown in FIGS. 3 and 4. FIG.

<Example 4>

To the aqueous solution containing 120 mmol of NaBH ₄ , a mixed aqueous solution containing 18 mmol of CuCl _2, 10 mmol of SnCl _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 Cu-Sn bimetallic metal nanoparticles in which Cu ₆ Sn ₅ and Cu ₄₁ Sn ₁₁ were mixed.

The Cu-Sn bimetallic metal nanoparticles were dispersed in 100 ml of distilled water, and then an aqueous solution containing 11 mmol of zinc acetate and 12 mmol of NaHSe was sequentially added to prepare a flocculated complex comprising Cu-Sn phase and ZnSe phase Respectively.

&Lt; Example 5 >

A mixed solution containing 20 mmol of CuCl ₂ and 10 mmol of SnCl ₂ was added dropwise to the DMSO solution containing 80 mmol of NaBH ₄ over 1 hour, and the mixture was reacted for 24 hours to react, and the formed particles were separated by centrifugation And purified to prepare Cu-Sn bimetallic metal nanoparticles.

The Cu-Sn bimetallic metal nanoparticles were dispersed in 200 ml of distilled water, and a solution of 12 mmol of ZnCl ₂ and 0.5 g of PVP dissolved in 100 ml of distilled water was added dropwise. Na ₂ S solution dissolved in distilled water was slowly added dropwise to the obtained mixed solution and stirred for 5 hours to prepare a flocculated composite comprising Cu-Sn phase and ZnS phase.

&Lt; Example 6 >

A mixed aqueous solution containing 16 mmol of CuCl ₂ and 10 mmol of SnCl ₄ was added dropwise to the aqueous solution containing 120 mmol of NaBH ₄ over 1 hour, and the mixture was reacted for 24 hours to react, and the formed particles were purified by centrifugation To prepare Cu-Sn bimetallic metal nanoparticles.

After dispersing the Cu-Sn bimetallic metal nanoparticles in butoxyethanol, a solution obtained by dissolving 11 mmol and 22 mmol of zinc acetate and thiourea, respectively, was added and reacted at 150 ° C. for 3 hours to form a Cu-Sn phase and a ZnS phase To prepare a flocculated composite.

&Lt; Example 7 >

A mixed aqueous solution containing 16 mmol of CuCl ₂ and 10 mmol of SnCl ₄ was added dropwise to the aqueous solution containing 120 mmol of NaBH ₄ over 1 hour, and the mixture was reacted for 24 hours to react, and the formed particles were purified by centrifugation To prepare Cu-Sn bimetallic metal nanoparticles.

After the Cu-Sn bimetallic metal nanoparticles were dispersed in ethanol, a solution prepared by dissolving 11 mmol, 10 mmol, and 22 mmol of zinc acetate, ethanedithiol, and thioacetamide in 50 ml of ethanol was added, And reacted for 3 hours to prepare a flocculated composite comprising Cu-Sn phase and ZnS phase.

&Lt; Example 8 >

A mixed aqueous solution containing 18 mmol of CuCl ₂ and 10 mmol of SnCl ₂ was added dropwise to a dimethylformamide solution containing 120 mmol of NaBH ₄ over 1 hour and then reacted for 24 hours to effect reaction. And then purified by a separation method to prepare Cu-Sn bimetallic metal nanoparticles.

After the Cu-Sn bimetallic metal nanoparticles were dispersed in isopropanol, a solution of 10 mmol and 15 mmol of ZnCl ₂ and thioacetamide, respectively, was added and reacted at 80 ° C. for 3 hours to form Cu-Sn phase and ZnS phase To prepare a flocculated composite.

&Lt; Example 9 >

DMSO solution containing 14 mmol of Cu (NO ₃ ) ₂ and 10 mmol of SnCl ₄ 5H ₂ O was added dropwise to the DMSO solution containing 80 mmol of NaBH ₄ at 60 ° C over 1 hour, followed by stirring for 6 hours And the formed particles were purified by centrifugation to prepare Cu-Sn bimetallic metal nanoparticles.

The Cu-Sn bimetalic metal nanoparticles were dispersed in 300 mL of ethanol, and then 15 mmol of zinc ethylxanthate was added thereto. The temperature was raised to 78 ° C and the mixture was stirred for 3 hours to form a Cu-Sn phase and a ZnS- Complex.

&Lt; Example 10 >

To the NMP solution containing 80 mmol of NaBH ₄ , a mixed solution containing 14 mmol of Cu (NO ₃ ) ₂ and 10 mmol of SnCl ₄ 5H ₂ O was added dropwise at 90 ° C over 1 hour, followed by stirring for 6 hours And the formed particles were purified by centrifugation to prepare Cu-Sn bimetallic metal nanoparticles.

The Cu-Sn bimetalic metal nanoparticles were dispersed in 300 mL of ethanol, and then 15 mmol of zinc ethylxanthate was added thereto. The temperature was raised to 78 ° C and the mixture was stirred for 3 hours to form a Cu-Sn phase and a ZnS- Complex.

&Lt; Example 11 >

To the distilled water containing 80 mmol of NaBH ₄ and 27 mmol of cysteamine, a mixed solution containing 17 mmol of CuCl ₂ and 10 mmol of SnCl ₄ 5H ₂ O was added dropwise at room temperature over 1 hour, followed by stirring for 5 hours And the formed particles were purified by centrifugation to prepare Cu-Sn bimetallic metal nanoparticles.

The Cu-Sn bimetalic metal nanoparticles were dispersed in 300 mL of ethanol, and then 15 mmol of zinc ethylxanthate was added thereto. The temperature was raised to 78 ° C and the mixture was stirred for 3 hours to form a Cu-Sn phase and a ZnS- Complex.

An electron microscope (SEM) photograph of the formed particles and an XRD graph are shown in FIGS. 5 and 6. FIG. 7 and 8 show the results of the composition analysis of the particles using the TEM analysis and the line scan. Referring to the XRD analysis results of FIGS. 5 and 6, the particles are in a mixed state of a Cu-Sn bimetallic phase and a ZnS crystal phase in which a Cu ₆ Sn ₅ crystal phase and a Cu-rich Cu-Sn crystal phase are mixed It can be seen that the Cu-Sn phase and the ZnS phase exist as a uniformly distributed aggregation complex or exist as nanoparticles of core-shell structure in which Cu-Sn is coated with ZnS.

&Lt; Example 12 >

To the distilled water containing 80 mmol of NaBH ₄ and 27 mmol of cysteamine, a mixed solution containing 17 mmol of Cu (NO ₃ ) ₂ and 10 mmol of SnCl ₄ 5H ₂ O was added dropwise at room temperature over 1 hour, For a period of time, and the formed particles were purified by centrifugation to prepare Cu-Sn bimetallic metal nanoparticles.

The Cu-Sn bimetalic metal nanoparticles were dispersed in 300 mL of ethanol, and then 15 mmol of zinc ethylxanthate was added thereto. The temperature was raised to 78 ° C and the mixture was stirred for 3 hours to form a Cu-Sn phase and a ZnS- Complex.

&Lt; Example 13 >

270 mmol of NaBH ₄ , 27 mmol of cysteamine, 17 mmol of CuCl ₂ .2H ₂ O and 10 mmol of SnCl ₄ 5H ₂ O was added dropwise at room temperature over 1 hour, For a period of time, and the formed particles were purified by centrifugation to prepare Cu-Sn bimetallic metal nanoparticles.

The Cu-Sn bimetallic metal nanoparticles were dispersed in 300 mL of ethanol and then dissolved with 10 mmol of zinc acetate and 20 mmol of thioacetamide. The temperature was raised to 70 ° C., and the mixture was stirred for 3 hours. ZnS phase was prepared.

&Lt; Example 14 >

270 mmol of NaBH ₄ , 27 mmol of cysteamine, 17 mmol of CuCl ₂ .2H ₂ O and 10 mmol of SnCl ₄ 5H ₂ O was added dropwise at room temperature over 1 hour, For a period of time, and the formed particles were purified by centrifugation to prepare Cu-Sn bimetallic metal nanoparticles.

The Cu-Sn bimetallic metal nanoparticles were dispersed in ethanol (300 mL), and then 10 mmol of zinc acetate, 20 mmol of thioacetamide and 10 mmol of cysteamine were dissolved therein, and the temperature was raised to 70 ° C. After stirring for 3 hours, -Sn phase and ZnS phase was prepared.

&Lt; Example 15 >

270 mmol of NaBH ₄ and 27 mmol of mercaptoethanol was added dropwise to the mixed solution containing 17 mmol of CuCl ₂ .2H ₂ O and 10 mmol of SnCl ₄ 5H ₂ O at room temperature over 1 hour, For a period of time, and the formed particles were purified by centrifugation to prepare Cu-Sn bimetallic metal nanoparticles.

The Cu-Sn bimetallic metal nanoparticles were dispersed in ethanol (300 mL), and then 10 mmol of zinc acetate, 20 mmol of thioacetamide and 10 mmol of mercaptoethanol were dissolved therein. The temperature was raised to 70 ° C., and the mixture was stirred for 3 hours. -Sn phase and ZnS phase was prepared.

&Lt; Example 16 >

A mixed aqueous solution containing 280 mmol of NaBH ₄ , 18 mmol of Cu (NO ₃ ) ₂ , 10 mmol of SnCl ₂ and 28 mmol of trisodium citrate was added dropwise at room temperature over 1 hour, And the resulting particles were purified by centrifugal separation to prepare Cu-Sn bimetallic metal nanoparticles in which Cu ₆ Sn ₅ and Cu ₄₁ Sn ₁₁ were mixed.

The Cu-Sn bimetallic metal nanoparticles were dispersed in ethanol (300 mL), and then 10 mmol of zinc acetate, 20 mmol of thioacetamide and 10 mmol of mercaptoethanol were dissolved therein. The temperature was raised to 70 ° C., and the mixture was stirred for 3 hours. -Sn phase and ZnS phase was prepared.

&Lt; Example 17 >

To a distilled water solution containing 270 mmol of NaBH ₄ , 27 mmol of cysteamine hydrochloride and 27 mmol of NaOH was added a mixed solution containing 17 mmol of CuCl ₂ .2H ₂ O and 10 mmol of SnCl ₄ 5H ₂ O at room temperature for 1 hour And the mixture was stirred for 5 hours to react. The formed particles were then purified by centrifugation to prepare Cu-Sn bimetallic metal nanoparticles.

The Cu-Sn bimetallic metal nanoparticles were dispersed in 300 mL of distilled water, and then 10 mmol of zinc acetate and 20 mmol of thioacetamide were dissolved therein. After the temperature was elevated to 70 ° C, the mixture was stirred for 3 hours, ZnS phase was prepared.

&Lt; Example 18 >

270 mmol of NaBH ₄ , 27 mmol of cysteamine hydrochloride, 17 mmol of CuCl ₂ .2H ₂ O and 10 mmol of SnCl ₄ 5H ₂ O was added dropwise at room temperature over 0.5 hours, Followed by stirring for 5 hours. The formed particles were purified by centrifugation to prepare Cu-Sn bimetallic metal nanoparticles.

The Cu-Sn bimetallic metal nanoparticles were dispersed in 300 mL of distilled water, and then 10 mmol of zinc acetate, 20 mmol of thioacetamide and 5 mL of NH ₄ OH were added thereto, and the temperature was raised to 50 ° C. The mixture was stirred for 3 hours , A Cu-Sn phase and a ZnS phase were prepared.

&Lt; Example 19 >

300 mmol of NaBH ₄ and 27 mmol of cysteamine hydrochloride were added 17 mmol of CuCl ₂ .2H ₂ O and 10 mmol of SnCl ₂ and 28 mmol of trisodium citrate at room temperature The mixture was added dropwise over 1 hour, and the mixture was reacted for 4 hours with stirring. The formed particles were purified by centrifugation to prepare Cu-Sn bimetallic metal nanoparticles.

The Cu-Sn bimetallic metal nanoparticles were dispersed in ethanol (300 mL), and then 10 mmol of zinc acetate, 20 mmol of thioacetamide and 10 mmol of mercaptoethanol were dissolved therein. The temperature was raised to 70 ° C., and the mixture was stirred for 3 hours. -Sn phase and ZnS phase was prepared.

&Lt; Example 20 >

To the distilled water containing 300 mmol of NaBH ₄ and 27 mmol of cysteamine hydrochloride was added a mixed solution containing 17 mmol of CuCl ₂ .2H ₂ O and 10 mmol of SnCl ₄ 5H ₂ O and 28 mmol of trisodium citrate Was added dropwise at room temperature over 1 hour, and the mixture was reacted for 4 hours with stirring. The formed particles were purified by centrifugation to prepare Cu-Sn bimetallic metal nanoparticles.

The Cu-Sn bimetallic metal nanoparticles were dispersed in ethanol (300 mL), and then 10 mmol of zinc acetate, 20 mmol of thioacetamide and 10 mmol of cysteamine were dissolved therein, and the temperature was raised to 70 ° C. After stirring for 3 hours, -Sn phase and ZnS phase was prepared.

&Lt; Example 21 >

300 mmol of NaBH ₄ and 27 mmol of cysteamine hydrochloride were added 17 mmol of CuCl ₂ .2H ₂ O and 10 mmol of SnCl ₂ and 28 mmol of trisodium citrate at room temperature The mixture was added dropwise over 1 hour, and the mixture was reacted for 4 hours with stirring. The formed particles were purified by centrifugation to prepare Cu-Sn bimetallic metal nanoparticles.

The Cu-Sn bimetallic metal nanoparticles were dispersed in 300 mL of ethanol, and then 10 mmol of zinc acetate, 20 mmol of thioacetamide and 5 mmol of ascorbic acid were dissolved therein. The temperature was raised to 70 ° C., and the mixture was stirred for 3 hours. Cu-Sn phase and ZnS phase.

&Lt; Example 22 >

DMSO solution containing 14 mmol of Cu (NO ₃ ) ₂ and 10 mmol of SnCl ₄ 5H ₂ O was added dropwise to the DMSO solution containing 80 mmol of NaBH ₄ at 60 ° C over 1 hour, followed by stirring for 6 hours And the formed particles were purified by centrifugation to prepare Cu-Sn bimetallic metal nanoparticles.

The Cu-Sn bimetallic metal nanoparticles are dispersed in 300 mL of ethanol, and then 15 mmol of zinc ethylxanthate is dissolved therein. The temperature is raised to 78 ° C. and the mixture is stirred for 3 hours. After washing, the mixture was dispersed in 100 mL of ethanol and added dropwise to a solution obtained by dissolving 3 mmol of CuCl _{2 in} 50 mL of ethanol, followed by stirring for 12 hours to prepare a flocculated complex comprising Cu-Sn phase and ZnS-CuS phase.

Line-scan results, electron microscope (SEM) photographs and XRD graphs of the formed particles are shown in Figures 9-11.

As a result of X-ray diffraction analysis, Cu-Sn bimetallic phase in which a Cu ₆ Sn ₅ crystal phase and a Cu-rich Cu-Sn crystal phase were mixed, ZnS-CuS crystal phases were mixed, and Cu-Sn And ZnS-CuS phases are present as homogeneously distributed aggregate complexes or as nanoparticles of core-shell structure in which CuS is coated with ZnS and CuS.

&Lt; Example 23 >

To the NMP solution containing 80 mmol of NaBH ₄ , a mixed solution containing 14 mmol of Cu (NO ₃ ) ₂ and 10 mmol of SnCl ₄ 5H ₂ O was added dropwise at 90 ° C over 1 hour, followed by stirring for 6 hours And the formed particles were purified by centrifugation to prepare Cu-Sn bimetallic metal nanoparticles.

The Cu-Sn bimetallic metal nanoparticles are dispersed in 300 mL of ethanol, and then 15 mmol of zinc ethylxanthate is dissolved therein. The temperature is raised to 78 ° C. and the mixture is stirred for 3 hours. After washing, the mixture was dispersed in 100 mL of ethanol and added dropwise to a solution obtained by dissolving 3 mmol of CuCl _{2 in} 50 mL of ethanol, followed by stirring for 12 hours to prepare a flocculated complex comprising Cu-Sn phase and ZnS-CuS phase.

&Lt; Example 24 >

To the distilled water containing 80 mmol of NaBH ₄ and 27 mmol of cysteamine, a mixed solution containing 17 mmol of CuCl ₂ and 10 mmol of SnCl ₄ 5H ₂ O was added dropwise at room temperature over 1 hour, followed by stirring for 5 hours And the formed particles were purified by centrifugation to prepare Cu-Sn bimetallic metal nanoparticles.

The Cu-Sn bimetallic metal nanoparticles are dispersed in 300 mL of ethanol, and then 15 mmol of zinc ethylxanthate is dissolved therein. The temperature is raised to 78 ° C. and the mixture is stirred for 3 hours. After washing, the mixture was dispersed in 100 mL of ethanol and added dropwise to a solution obtained by dissolving 3 mmol of CuCl _{2 in} 50 mL of ethanol, followed by stirring for 12 hours to prepare a flocculated complex comprising Cu-Sn phase and ZnS-CuS phase.

An electron microscope (SEM) photograph and XRD graph of the formed particles are shown in FIGS. 12 and 13. FIG.

&Lt; Example 25 >

To the distilled water containing 80 mmol of NaBH ₄ and 27 mmol of cysteamine, a mixed solution containing 17 mmol of Cu (NO ₃ ) ₂ and 10 mmol of SnCl ₄ 5H ₂ O was added dropwise at room temperature over 1 hour, For a period of time, and the formed particles were purified by centrifugation to prepare Cu-Sn bimetallic metal nanoparticles.

The Cu-Sn bimetallic metal nanoparticles are dispersed in 300 mL of ethanol, and then 15 mmol of zinc ethylxanthate is dissolved therein. The temperature is raised to 78 ° C. and the mixture is stirred for 3 hours. After washing, the mixture was dispersed in 100 mL of ethanol and added dropwise to a solution obtained by dissolving 3 mmol of CuCl _{2 in} 50 mL of ethanol, followed by stirring for 12 hours to prepare a flocculated complex comprising Cu-Sn phase and ZnS-CuS phase.

&Lt; Example 26 >

To the distilled water containing 80 mmol of NaBH ₄ and 27 mmol of cysteamine, a mixed solution containing 17 mmol of Cu (NO ₃ ) ₂ and 10 mmol of SnCl ₄ 5H ₂ O was added dropwise at room temperature over 1 hour, For a period of time, and the formed particles were purified by centrifugation to prepare Cu-Sn bimetallic metal nanoparticles.

A solution prepared by dissolving 15 mmol of zinc nitrate in 50 ml of water was added to a solution of Cu-Sn bimetallic metal nanoparticles dispersed therein. The solution was stirred for 1 hour and then a solution of 15 mmol of Na ₂ S dissolved in 70 ml of distilled water was added dropwise over 1 hour And reacted for 3 hours. Then, 3 mmol of CuCl ₂ was further added to the reaction solution and reacted at 25 ° C. to prepare a precursor including the nanoparticles of the Cu-Sn core ZnS-CuS shell structure.

&Lt; Example 27 >

Tetraethylene glycol mixed solution containing 18 mmol of CuCl ₂ and 10 mmol of SnCl ₂ was slowly added dropwise to a mixed solution of triethyleneglycol containing 150 mmol of NaBH ₄ and then stirred and reacted for 3 hours to purify Cu Sn bimetallic metal nanoparticles were prepared by mixing ₆ Sn ₅ and Cu-rich Cu-Sn (Cu ₄₁ Sn ₁₁ ).

A solution prepared by dissolving 15 mmol of zinc nitrate in 50 ml of water was added to a solution of Cu-Sn bimetallic metal nanoparticles dispersed therein. The solution was stirred for 1 hour and then a solution prepared by dissolving 15 mmol of Na ₂ S in 70 ml of distilled water was added over 1 hour The reaction mixture was reacted for 3 hours. Then, 3 mmol of CuCl ₂ was added to the reaction mixture and reacted at 25 ° C. to prepare a precursor including the nanoparticles of the Cu-Sn core ZnS-CuS shell structure.

&Lt; Example 28 >

Aqueous solution containing 15 mmol of CuCl ₂ and 10 mmol of SnCl ₂ was slowly added dropwise at 50 ° C. to the distilled water solution in which 150 mmol of NaBH ₄ had been dissolved and then reacted and refined for 1 hour to obtain Cu ₆ Sn ₅ Sn-bimetallic metal nanoparticles having a Cu-rich Cu-Sn phase, for example, Cu ₃ Sn, Cu ₁₀ Sn ₃ , or Cu ₄₁ Sn ₁₁ mixed therein was prepared.

A solution prepared by dissolving 15 mmol of zinc nitrate in 50 ml of water was added to a solution of Cu-Sn bimetallic metal nanoparticles dispersed therein. The solution was stirred for 1 hour and then a solution prepared by dissolving 15 mmol of Na ₂ S in 70 ml of distilled water was added over 1 hour The reaction mixture was reacted for 3 hours. Then, 3 mmol of CuCl ₂ was added to the reaction mixture and reacted at 25 ° C. to prepare a precursor including the nanoparticles of the Cu-Sn core ZnS-CuS shell structure.

&Lt; Example 29 >

A mixed solution containing 20 mmol of CuCl ₂ and 10 mmol of SnCl ₂ was added dropwise to the DMSO solution containing 150 mmol of NaBH ₄ at 80 ° C over 1 hour and then reacted for 24 hours to react the particles. Cu-Sn bimetallic metal nanoparticles composed of a mixed phase of Cu _6.26 Sn ₅ and Cu ₁₀ Sn ₃ were prepared.

A solution of 15 mmol of zinc nitrate in 50 ml of water was added to a solution of Cu-Sn bimetallic metal nanoparticles dispersed therein, and the mixture was stirred for 1 hour. A solution of 15 mmol of Na ₂ S in 70 ml of distilled water was added dropwise over 1 hour , And reacted for 3 hours. Thereafter, 3 mmol of CuCl ₂ was added to the reaction solution and reacted at 25 ° C. to prepare a precursor including the nanoparticles of the Cu-Sn core ZnS-CuS shell structure.

&Lt; Example 30 >

To the aqueous solution containing 120 mmol of NaBH ₄ , a mixed aqueous solution containing 18 mmol of CuCl ₂ , 10 mmol of SnCl 2 and 50 mmol of trisodium citrate was added dropwise over 1 hour, and the mixture was stirred for 24 hours And the formed particles were purified by centrifugation to prepare Cu-Sn bimetallic metal nanoparticles in which Cu ₆ Sn ₅ and Cu ₄₁ Sn ₁₁ were mixed.

A solution prepared by dissolving 15 mmol of zinc nitrate in 50 ml of water was added to a solution of Cu-Sn bimetallic metal nanoparticles dispersed therein. The solution was stirred for 1 hour and then a solution prepared by dissolving 15 mmol of Na ₂ S in 70 ml of distilled water was added over 1 hour After the reaction was carried out for 3 hours,

3 mmol of CuCl ₂ was further added to the reaction mixture and reacted at 25 ° C. to prepare a precursor including nanoparticles of Cu-Sn core ZnS-CuS shell structure.

&Lt; Example 31 >

A mixed aqueous solution containing 16 mmol of CuCl ₂ and 10 mmol of SnCl ₄ was added dropwise to the aqueous solution containing 120 mmol of NaBH ₄ over 1 hour, and the mixture was reacted for 24 hours to react, and the formed particles were purified by centrifugation To prepare Cu-Sn bimetallic metal nanoparticles.

A solution prepared by dissolving 15 mmol of zinc nitrate in 50 ml of water was added to a solution of Cu-Sn bimetallic metal nanoparticles dispersed therein. The solution was stirred for 1 hour and then a solution prepared by dissolving 15 mmol of Na ₂ S in 70 ml of distilled water was added over 1 hour The reaction mixture was reacted for 3 hours. Then, 3 mmol of CuCl ₂ was added to the reaction mixture and reacted at 25 ° C. to prepare a precursor including the nanoparticles of the Cu-Sn core ZnS-CuS shell structure.

&Lt; Example 32 >

A mixed aqueous solution containing 16 mmol of CuCl ₂ and 10 mmol of SnCl ₄ was added dropwise to the aqueous solution containing 120 mmol of NaBH ₄ over 1 hour, and the mixture was reacted for 24 hours to react, and the formed particles were purified by centrifugation To prepare Cu-Sn bimetallic metal nanoparticles.

A solution prepared by dissolving 15 mmol of zinc acetate in 50 ml of water was added to a solution of Cu-Sn bimetallic metal nanoparticles dispersed therein, which was stirred for 1 hour. Then, 15 mmol of Na ₂ S dissolved in 70 ml of distilled water Was added dropwise over 1 hour, and the mixture was reacted for 3 hours. Then, 3 mmol of CuCl ₂ was further added to the reaction mixture and reacted at 25 ° C to prepare a precursor including a Cu-Sn core ZnS-CuS shell structure .

&Lt; Example 33 >

A mixed aqueous solution containing 18 mmol of CuCl ₂ and 10 mmol of SnCl ₂ was added dropwise to a dimethylformamide solution containing 120 mmol of NaBH ₄ over 1 hour and then reacted for 24 hours to effect reaction. And then purified by a separation method to prepare Cu-Sn bimetallic metal nanoparticles.

After dispersing the Cu-Sn bimetallic metal nanoparticles in isopropanol, a solution prepared by dissolving 10 mmol and 15 mmol of ZnCl ₂ and thioacetamide, respectively, was added and reacted at 80 ° C. for 3 hours. Then, 3 mmol of CuCl ₂ And reacted at 25 ° C to prepare a flocculated composite comprising Cu-Sn phase and ZnS-CuS phase.

&Lt; Example 34 >

300 mmol of NaBH ₄ and 27 mmol of cysteamine hydrochloride were added 17 mmol of CuCl ₂ .2H ₂ O and 10 mmol of SnCl ₂ and 28 mmol of trisodium citrate at room temperature The mixture was added dropwise over 1 hour, and the mixture was reacted for 4 hours with stirring. The formed particles were purified by centrifugation to prepare Cu-Sn bimetallic metal nanoparticles.

After dispersing the Cu-Sn by metallic metal nanoparticle in ethanol 300 mL, zinc acetate 10 mmol and dissolved into the thioacetamide 20 mmol and mercaptoethanol 10 mmol, after which reaction for 3 hours at 80 °, again CuCl ₂ 3 mmol Was added and reacted at 25 ° C to prepare a flocculated composite comprising Cu-Sn phase and ZnS-CuS phase.

&Lt; Comparative Example 1 &

5 mmol of zinc nitrate salt solution and 10 mmol of Na ₂ S were dissolved in 100 ml of distilled water, mixed and reacted at room temperature for 5 hours, and the formed particles were purified by centrifugation to prepare ZnS nanoparticles.

&Lt; Comparative Example 2 &

5 mmol of aqueous solution of copper chloride and 10 mmol of Na ₂ S were dissolved in 100 ml of distilled water. The mixture was heated to 50 ° C for 2 hours, and the particles were purified by centrifugation to prepare CuS nanoparticles.

&Lt; Comparative Example 3 &

5 mmol of tin chloride aqueous solution and 10 mmol of Na ₂ S were dissolved in 100 ml of distilled water. The mixture was heated to 50 ° C. for 2 hours, and the formed particles were purified by centrifugation to prepare SnS nanoparticles.

&Lt; Comparative Example 4 &

100 ml of aqueous solution of 5 mmol of zinc chloride solution and 100 ml of aqueous 10 mM NaHSe solution were mixed and reacted at room temperature for 5 hours. The formed particles were purified by centrifugation to prepare ZnSe nanoparticles.

&Lt; Example 35 >

Manufacture of thin films

The Cu-Sn / ZnS precursor prepared in Example 1 was dissolved in ethanol, ethylene glycol monomethyl ether, acetylacetone, propylene glycol propyl ether, cyclohexanone, ethanolamine, 1,2-propanediol, diethylene glycol monoethyl ether , Glycerol, and sodium dodecyl sulfate, and then dispersed at a concentration of 21% to prepare an ink. The obtained ink was coated on the Mo thin film coated on the glass and dried to 200 ° C. CZTS thin films were obtained by heat treatment at 550 ℃ in the presence of Se. The sectional shape and XRD image of the obtained thin film are shown in Figs. 14 and 15. Fig. Referring to FIGS. 14 and 15, it can be seen that the thin film produced according to the present invention has uniform composition, high density, and good grain growth.

&Lt; Example 36 >

Manufacture of thin films

A CZTS thin film was obtained in the same manner as in Example 35 except that the precursor prepared in Example 2 was used.

&Lt; Example 37 >

Manufacture of thin films

A CZTS thin film was obtained in the same manner as in Example 35 except that the precursor prepared in Example 3 was used. SEM photographs of the cross-sectional shapes of the obtained thin films are shown in FIG. Referring to FIG. 16, it can be seen that the thin film produced according to the present invention has a high density and a good growth of grain.

&Lt; Example 38 >

Manufacture of thin films

A CZTS thin film was obtained in the same manner as in Example 35 except that the precursor prepared in Example 4 was used.

&Lt; Example 39 >

Manufacture of thin films

A CZTS thin film was obtained in the same manner as in Example 35 except that the precursor prepared in Example 5 was used.

&Lt; Example 40 >

Manufacture of thin films

A CZTS thin film was obtained in the same manner as in Example 35 except that the precursor prepared in Example 6 was used.

&Lt; Example 41 >

Manufacture of thin films

A CZTS thin film was obtained in the same manner as in Example 35 except that the precursor prepared in Example 7 was used.

&Lt; Example 42 >

Manufacture of thin films

A CZTS thin film was obtained in the same manner as in Example 35 except that the precursor prepared in Example 8 was used.

&Lt; Example 43 >

Manufacture of thin films

A CZTS thin film was obtained in the same manner as in Example 35 except that the precursor prepared in Example 9 was used. SEM photographs of the cross-sectional shapes of the obtained thin films and the compositional analysis results by XRD graphs are shown in FIGS. 17 and 18. FIG. Referring to FIG. 17, it can be seen that the thin film produced according to the present invention has a high density and a good growth of grain.

&Lt; Example 44 >

Manufacture of thin films

A CZTS thin film was obtained in the same manner as in Example 35 except that the precursor prepared in Example 10 was used.

&Lt; Example 45 >

Manufacture of thin films

A CZTS thin film was obtained in the same manner as in Example 35 except that the precursor prepared in Example 11 was used.

&Lt; Example 46 >

Manufacture of thin films

A CZTS thin film was obtained in the same manner as in Example 35 except that the precursor prepared in Example 12 was used.

&Lt; Example 47 >

Manufacture of thin films

A CZTS thin film was obtained in the same manner as in Example 35 except that the precursor prepared in Example 22 was used. SEM photographs and XRD images of the cross-sectional shapes of the obtained thin films are shown in Figs. 19 and 20.

&Lt; Example 48 >

Manufacture of thin films

A CZTS thin film was obtained in the same manner as in Example 35 except that the precursor prepared in Example 24 was used. SEM photographs and EDX results of the cross-sectional shapes of the obtained thin films are shown in FIGS. 21 and 22.

&Lt; Comparative Example 5 &

Manufacture of thin films

Cu-Sn The metal nanoparticles and the ZnS nanoparticles prepared in Comparative Example 1 were mixed in a ratio of Cu / (Zn + Sn) = 0.9 and Zn / Sn = 1.2 to prepare ethanol, ethylene glycol monomethyl ether, acetylacetone, Was added to a mixed solvent composed of ether, cyclohexanone, ethanolamine, 1,2-propanediol, diethylene glycol monoethyl ether, glycerol, and sodium dodecyl sulfate, and then dispersed at a concentration of 21% to prepare an ink. The obtained ink was coated on the Mo thin film coated on the glass and dried to 200 ° C. CZTS thin films were obtained by heat treatment at 550 ℃ in the presence of Se.

&Lt; Comparative Example 6 >

Manufacture of thin films

Cu-Sn The metal nanoparticles and the ZnSe nanoparticles prepared in Comparative Example 4 were mixed in a ratio of Cu / (Zn + Sn) = 0.8 and Zn / Sn = 1.1 to prepare ethanol, ethylene glycol monomethyl ether, acetylacetone, Was added to a mixed solvent composed of ether, cyclohexanone, ethanolamine, 1,2-propanediol, diethylene glycol monoethyl ether, glycerol, and sodium dodecyl sulfate, and then dispersed at a concentration of 21% to prepare an ink. The obtained ink was coated on the Mo thin film coated on the glass and dried to 200 ° C. CZTS thin films were obtained by heat treatment at 550 ℃ in the presence of Se.

&Lt; Comparative Example 7 &

Manufacture of thin films

The ZnS nanoparticles, CuS nanoparticles, and SnS nanoparticles prepared in Comparative Examples 1 to 3 were mixed so as to have a ratio of Cu / (Zn + Sn) = 0.9 and Zn / Sn = 1.2 to prepare ethanol, ethylene glycol monomethyl ether, Was added to a mixed solvent composed of acetone, propylene glycol propyl ether, cyclohexanone, ethanolamine, 1,2-propanediol, diethylene glycol monoethyl ether, glycerol and sodium dodecyl sulfate, and then dispersed at a concentration of 21% . The obtained ink was coated on the Mo thin film coated on the glass and dried to 200 ° C. CZTS thin films were obtained by heat treatment at 550 ℃ in the presence of Se. SEM photographs and EDX results of the cross-sectional shapes of the obtained thin films are shown in FIGS. 23 and 24.

<Experimental Example 1>

A CdS buffer layer was prepared on the CZTS thin films prepared in Examples 35 to 37, 44 to 48 and Comparative Examples 5 to 7 by a CBD method and ZnO and Al: ZnO were sequentially deposited by a sputtering method, and then the Ag electrode was raised by screen printing cells. The characteristics obtained from the cells are shown in Table 1 below. Further, as a representative example, the graph of the characteristics obtained from the cell using the thin films of Examples 37 and 48 and the IV characteristic graph obtained in Comparative Example 7 are shown in FIGS. 25, 26, and 27.

J _sc (mA / cm ² ) V _oc (V) FF (%) Photoelectric efficiency (%) Example 35 27.37 0.41 42.7 4.8 Example 36 24.46 0.34 40.69 3.4 Example 37 31.83 0.37 35.44 4.2 Example 44 27.87 0.33 35.64 3.3 Example 45 28.11 0.33 38.90 3.6 Example 46 31.67 0.33 33.98 3.5 Example 47 29.5 0.31 43.91 4.0 Example 48 33.83 0.35 44.08 5.3 Comparative Example 5 18.9 0.20 33.4 1.3 Comparative Example 6 12.7 0.15 36.1 0.7 Comparative Example 7 19.6 0.23 28.40 1.3

25 to 27 and Table 1, J _sc denotes a current density, V _oc denotes an open circuit voltage measured at zero output current, and photoelectric efficiency denotes a current density (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 V _oc and J _sc . Also, V _mp means the voltage at the maximum power point, and J _mp means the current value at the maximum power point.

25 to 27 and Table 1, in the case of Examples 35 to 37 and 44 to 48 in which a CZTS thin film was formed using the precursor produced according to the present invention, metal nanoparticles or metal chalcogenide were separately prepared As compared with Comparative Examples 5 to 7 in which a thin film was prepared by mixing, the current density and the voltage were high, indicating excellent photoelectric efficiency. Compared with Examples 35 to 37 and 44 to 46 in which a CZTS thin film was formed using a precursor containing no Cu in the shell portion even in the precursor of the same core-shell structure, a precursor containing Cu was added to the shell portion In the case of Examples 47 and 48 in which the CZTS thin film was formed by using the photoresist composition of the present invention, the FF value was particularly improved, indicating excellent photovoltaic efficiency.

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 (26)

delete delete delete delete delete delete delete delete delete delete delete delete A method for producing a precursor for the production of a light absorbing layer of a solar cell,
The precursor for the production of the light absorbing layer may include,
(a) a first phase consisting of a copper (Cu) -stannard (Sn) bimetallic metal and a second phase consisting of a zinc-containing chalcogenide,
A first phase consisting of a copper (Cu) -stin (Sn) bimetallic metal, a second phase consisting of a zinc-containing chalcogenide and a second phase consisting of a copper- An agglomerated complex comprising a third phase consisting essentially of NaI; or
(b) a core made of copper (Cu) -stin (Sn) bimetallic metal nanoparticles, a chalcogenide containing zinc or a chalcogenide containing zinc and a chalcogenide containing copper Nanoparticles of a core-shell structure comprising a shell of a nide; or
(c) these mixtures;
Respectively,
The method comprises:
(i) preparing a first solution containing a reducing agent and a second solution containing a copper (Cu) salt and a tin (Sn) salt;
(ii) synthesizing copper (Cu) -stin (Sn) bismuth metal nanoparticles by mixing and reacting the first solution and the second solution;
(iii) mixing and reacting a zinc (Zn) -ligand complex with a solution of the Cu-Sn bimetallic metal nanoparticles dispersed in the step (ii); And
(iv) adding a copper (Cu) salt to the reactant in the step (iii) to synthesize a precursor for the preparation of a light absorbing layer through a Zn-Cu substitution reaction and then refining;
Wherein the method comprises the steps of: delete A method for producing a precursor for the production of a light absorbing layer of a solar cell,
The precursor for the production of the light absorbing layer may include,
(a) a first phase consisting of a copper (Cu) -stannard (Sn) bimetallic metal and a second phase consisting of a zinc-containing chalcogenide,
A first phase consisting of a copper (Cu) -stin (Sn) bimetallic metal, a second phase consisting of a zinc-containing chalcogenide and a second phase consisting of a copper- An agglomerated complex comprising a third phase consisting essentially of NaI; or
(b) a core made of copper (Cu) -stin (Sn) bimetallic metal nanoparticles, a chalcogenide containing zinc or a chalcogenide containing zinc and a chalcogenide containing copper Nanoparticles of a core-shell structure comprising a shell of a nide; or
(c) these mixtures;
Respectively,
The method comprises:
(i) preparing a first solution containing a reducing agent and a second solution containing a copper (Cu) salt and a tin (Sn) salt;
(ii) synthesizing copper (Cu) -stin (Sn) bismuth metal nanoparticles by mixing and reacting the first solution and the second solution;
(iii) a third solution comprising at least one Group VI source selected from the group consisting of compounds comprising sulfur (S), selenium (Se), sulfur (S), and selenium (Se) , A zinc (Zn) salt;
(iv) mixing and reacting the third solution and the fourth solution in a solution in which the Cu-Sn bimetallic metal nanoparticles of the step (ii) are dispersed; And
(v) adding a copper (Cu) salt to the reactant in the step (iv) to synthesize a precursor for the preparation of a light absorbing layer through a Zn-Cu substitution reaction, and then purifying the precursor;
Wherein the method comprises the steps of: delete 14. The method of claim 13, wherein the solvent of the first and second solutions is selected from the group consisting of water, alcohols, diethylene glycol, oleylamine, ethyleneglycol, triethylene glycol wherein the at least one selected from the group consisting of triethylene glycol, dimethyl sulfoxide, dimethyl formamide and N-methyl-2-pyrrolidone (NMP) . The method of claim 13, wherein the salt of the copper (Cu) salt and the salt of tin (Sn) is independently selected from the group consisting of fluoride, chloride, bromide, iodide, nitrate Nitrate, sulfate, acetate, citrate, sulfite, acetylacetoate, acrylate, cyanide, and the like. , Phosphate (s), and hydroxide (s). The method for producing a precursor for a light-absorbing layer according to any one of claims 1 to 5, 14. The method according to claim 13, wherein the ligand included in the ligand conjugate is selected from the group consisting of:

Wherein R is ethyl. The method of claim 15, wherein the Group VI sources _{Se, Na 2 Se, K 2} Se, CaSe, (CH 3) 2 Se, SeO 2, SeS 2, Se 2 S 6, Se 2 Cl 2, Se 2 Br 2 , SeCl _4, SeBr _4, (CH ₃ ) ₂ S, H ₂ SO ₄ , Na ₂ S ₂ O ₃ , and NH ₂ SO ₃ H, or a mixture of these compounds, such as SeCO ₂ , H ₂ SeO ₃ , H ₂ SeO ₄ , S, Na ₂ S, K ₂ S, (S) of a compound of formula (I) or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier, such as HSCH ₂ COOH, thiolactic acid, mercaptoethanol, aminoheptanethiol, thiourea, thioacetamide, and selenourea Wherein the light absorbing layer is at least one selected from the group consisting of silver, gold, 14. The method of claim 13, wherein at least one of the first solution and the second solution further comprises a capping agent. 16. The method of claim 15, wherein the solvent of the first solution to the fourth solution is selected from the group consisting of water, alcohols, diethylene glycol, oleylamine, ethyleneglycol, wherein the at least one selected from the group consisting of triethylene glycol, dimethyl sulfoxide, dimethyl formamide and N-methyl-2-pyrrolidone (NMP) . The method of claim 15, wherein the salts of copper (Cu), tin (Sn), and zinc (Zn) salts are independently selected from the group consisting of fluoride, chloride, bromide, (iodide), nitrate, nitrite, sulfate, acetate, citrate, sulfite, acetylacetoate, acrylate, A cyanide, a phosphate, and a hydroxide. The method for producing a precursor for a light-absorbing layer according to claim 1, wherein the cyanide is at least one selected from the group consisting of cyanide, phosphate, and hydroxide. 16. The method of claim 15, wherein at least one of the first solution to the fourth solution further comprises a capping agent.


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