Ink composition for manufacturing light absorption layer of solar cells and method of manufacturing thin film using the same

Abstract

Disclosed are an ink composition for manufacturing a light absorption layer of solar cells and a method of manufacturing a thin film using the same. Particularly, an ink composition for manufacturing a light absorption layer of solar cells including core-shell structure nanoparticles including a core including a copper (Cu)-containing chalcogenide and a shell including a zinc (Zn)-containing chalcogenide; and tin (Sn)-containing bimetallic or intermetallic metal nanoparticles, or a tin (Sn)-containing chalcogenide nanoparticles, dispersed in a solvent, and a method of manufacturing a thin film using the same are disclosed.

Claims

1. An ink composition for manufacturing a light absorption layer of solar cells comprising core-shell structure nanoparticles comprising a core comprising a copper (Cu)-containing chalcogenide and a shell comprising a zinc (Zn)-containing chalcogenide; and tin (Sn)-containing bimetallic or intermetallic metal nanoparticles, or a tin (Sn)-containing chalcogenide nanoparticles, dispersed in a solvent.

2. The ink composition according to claim 1, wherein the core has a diameter of 20 nanometers to 200 nanometers.

3. The ink composition according to claim 1, wherein the shell has a thickness of 1 nanometers to 75 nanometers.

4. The ink composition according to claim 1, wherein the copper (Cu)-containing chalcogenide is at least one selected from the group consisting of CuS, Cu.sub.xS wherein 1.7x2.0, CuSe, and Cu.sub.ySe wherein 1.7y2.0.

5. The ink composition according to claim 1, wherein the zinc (Zn)-containing chalcogenide is ZnS, and/or ZnSe.

6. The ink composition according to claim 1, wherein the tin (Sn)-containing bimetallic or intermetallic metal nanoparticles are Cu.sub.3Sn or Cu.sub.6Sn.sub.5.

7. The ink composition according to claim 1, wherein the tin (Sn)-containing chalcogenide nanoparticles are Sn.sub.zS wherein 0.5z2.0 and/or Sn.sub.wSe wherein 0.5w2.0.

8. The ink composition according to claim 1, wherein the core-shell structure nanoparticles; and tin (Sn)-containing bimetallic or intermetallic metal nanoparticles or tin (Sn)-containing chalcogenide nanoparticles, are mixed satisfying 0.5<Cu/(Sn+Zn)<1.4.

9. The ink composition according to claim 1, wherein the solvent is at least one organic solvent selected from the group consisting of alkanes, alkenes, alkynes, aromatics, ketones, nitriles, ethers, esters, organic halides, alcohols, amines, thiols, carboxylic acids, phosphines, phosphates, sulfoxides, and amides.

10. The ink composition according to claim 1, wherein the ink composition further comprises an additive.

11. The ink composition according to claim 10, wherein the additive is at least one selected from the group consisting of polyvinylpyrrolidone (PVP), polyvinyl alcohol, Anti-terra 204, Anti-terra 205, ethyl cellulose, and DispersBYK110.

12. A method of synthesizing the core-shell structure nanoparticles according to claim 1, the method comprising: preparing a first solution comprising at least one Group VI source selected from the group consisting of compounds comprising sulfur (S), or selenium (Se), or sulfur (S) and selenium (Se); preparing a second solution comprising a copper (Cu) salt and a third solution comprising a zinc (Zn) salt; mixing the first solution and second solution to manufacture a mixture; synthesizing copper (Cu)-containing chalcogenide core particles through reaction of the mixture; and forming and then purifying a shell by mixing the third solution with a product comprising the core particles of the synthesizing.

13. The method according to claim 12, wherein solvents of the first solution, second solution and third solution are at least one selected from the group consisting of water, methanol, ethanol, glycol class solvents, oleylamine, dimethyl sulfoxide and dimethyl formamide.

14. The method according to claim 13, wherein the glycol class solvents are at least one selected from the group consisting of ethylene glycol, diethylene glycol, NMP, diethylene glycol mono ethyl ether (DEGMEE) and triethylene glycol.

15. The method according to claim 12, wherein the salt is at least one type selected from the group consisting of chlorides, nitrates, nitrites, sulfates, acetates, sulfites, acetylacetonates and hydroxides.

16. The method according to claim 12, wherein the Group VI source is at least one selected from the group consisting of Se, Na.sub.2Se, K.sub.2Se, Ca.sub.2Se, (CH.sub.3).sub.2Se, SeO.sub.2, SeCl.sub.4, H.sub.2SeO.sub.3, Na.sub.2S, K.sub.2S, Ca.sub.2S, (CH.sub.3).sub.2S, H.sub.2SO.sub.4, S, Na.sub.2S.sub.2O.sub.3, NH.sub.2SO.sub.3H and hydrates thereof.

17. The method according to claim 12, wherein the Group VI source is at least one selected from the group consisting of thiourea, thioacetamide and selenourea.

18. The method according to claim 12, wherein, in the mixture of the mixing, the Group VI source is comprised in an amount of 0.5 mol to 4 mol based on 1 mol of the copper (Cu) salt.

19. The method according to claim 12, wherein, when the third solution is mixed, the Group VI source is further added to the product comprising the core particles of the synthesizing.

20. A method of manufacturing a thin film using the ink composition for manufacturing the light absorption layer of solar cells according to claim 1, the method comprising: mixing core-shell structure nanoparticles; and tin (Sn)-containing bimetallic or intermetallic metal nanoparticles or tin (Sn)-containing chalcogenide nanoparticles, with a solvent to manufacture an ink composition; coating the ink composition on a base provided with an electrode; and drying and heat-treating the ink composition coated on the base provided with an electrode.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawing, in which:

(2) FIGS. 1A-1B are scanning electron microscope (SEM) images of CuS nanoparticles manufactured according to Manufacturing Example 1;

(3) FIG. 2 is an X-ray diffraction (XRD) graph of CuS nanoparticles manufactured according to Manufacturing Example 1;

(4) FIGS. 3A-3B are scanning electron microscope (SEM) images of CuS nanoparticles manufactured according to Manufacturing Example 5;

(5) FIG. 4 is an X-ray diffraction (XRD) graph of CuS nanoparticles manufactured according to Manufacturing Example 5;

(6) FIGS. 5A-5B are scanning electron microscope (SEM) images of CuS nanoparticles manufactured according to Manufacturing Example 8;

(7) FIG. 6 is an X-ray diffraction (XRD) graph of CuS nanoparticles manufactured according to Manufacturing Example 8;

(8) FIGS. 7A-7B are scanning electron microscope (SEM) images of CuS nanoparticles manufactured according to Manufacturing Example 12;

(9) FIG. 8 is an X-ray diffraction (XRD) graph of CuS nanoparticles manufactured according to Manufacturing Example 12;

(10) FIGS. 9A-9B are scanning electron microscope (SEM) images of CuS nanoparticles manufactured according to Manufacturing Example 13;

(11) FIG. 10 is an X-ray diffraction (XRD) graph of CuS nanoparticles manufactured according to Manufacturing Example 13;

(12) FIGS. 11A-11B are scanning electron microscope (SEM) images of CuS-core-ZnS-shell nanoparticles manufactured according to Manufacturing Example 17;

(13) FIG. 12 is a transmission electron microscope (TEM) image of CuS-core-ZnS-shell nanoparticles manufactured according to Manufacturing Example 17;

(14) FIGS. 13A-13B are scanning electron microscope (SEM) images of CuS-core-ZnS-shell nanoparticles manufactured according to Manufacturing Example 18;

(15) FIG. 14 is a transmission electron microscope (TEM) image of CuS-core-ZnS-shell nanoparticles manufactured according to Manufacturing Example 18;

(16) FIGS. 15A-15B are scanning electron microscope (SEM) images of CuS-core-ZnS-shell nanoparticles manufactured according to Manufacturing Example 19;

(17) FIG. 16 is a transmission electron microscope (TEM) image of CuS-core-ZnS-shell nanoparticles manufactured according to Manufacturing Example 19;

(18) FIGS. 17A-17B are scanning electron microscope (SEM) images of Cu.sub.6Sn.sub.5 particles manufactured according to Manufacturing Example 22;

(19) FIG. 18 is an XRD graph of Cu.sub.6Sn.sub.5 particles manufactured according to Manufacturing Example 22;

(20) FIGS. 19A-19D are scanning electron microscope (SEM) images of a CZTSSe thin film formed according to Example 1;

(21) FIG. 20 is X-ray diffraction (XRD) graph of a CZTSSe thin film formed according to Example 1;

(22) FIGS. 21A-21C are scanning electron microscope (SEM) images of a CZTSSe thin film formed according to Example 2;

(23) FIG. 22 is an X-ray diffraction (XRD) graph of a CZTSSe thin film formed according to Example 2; and

(24) FIGS. 23A-23D are scanning electron microscope (SEM) images of a CZTSSe thin film formed according to Comparative Example 1.

BEST MODE

(25) Now, the present invention will be described in more detail with reference to the following examples. These examples are provided only for illustration of the present invention and should not be construed as limiting the scope and spirit of the present invention.

Manufacturing Example 1

(26) Synthesis of CuS Particles

(27) To 150 mL of an aqueous solution including 5 mmol Na.sub.2S, 100 mL of an aqueous solution including 5 mmol of Cu(NO.sub.3).sub.2 was added dropwise. Subsequently, the solution was reacted while stirring for 2 hours. Formed particles were purified through centrifugation, resulting in CuS nanoparticles. A scanning electron microscope (SEM) image and XRD graph of the formed particles are illustrated in FIGS. 1 and 2.

Manufacturing Example 2

(28) Synthesis of CuS Particles

(29) 200 mL of an aqueous solution including 5 mmol of Cu(NO.sub.3).sub.2 and 10 mmol of thioacetamide was heated to 80 C. or more while stirring. Maintaining the temperature, the solution was reacted while stirring for 3 hours. Formed particles were purified through centrifugation, resulting in CuS nanoparticles.

Manufacturing Example 3

(30) Synthesis of CuS Particles

(31) 60 mL of an aqueous solution including 5 mmol of CuCl.sub.2 was heated to 80 C. or more. Subsequently, 60 mL of an aqueous solution including 10 mmol of thioacetamide was slowly added thereto and then was reacted while stirring for 3 hours. Formed particles were purified through centrifugation, resulting in CuS nanoparticles.

Manufacturing Example 4

(32) Synthesis of CuS Particles

(33) 60 ml of a diethylene glycol (DEG) solution including 5 mmol of Cu(NO.sub.3).sub.2 was heated to 60 C. or more. Subsequently, 60 ml of a DEG solution including 10 mmol of thioacetamide was added dropwise and then was reacted while stirring for 1 hour at 60 C. Formed particles were purified through centrifugation, resulting in CuS nanoparticles.

Manufacturing Example 5

(34) Synthesis of CuS Particles

(35) 300 ml of a DEG solution including 5 mmol of Cu(NO.sub.3).sub.2 was heated to 120 C. Subsequently, 100 mL of a DEG solution including 10 mmol of thioacetamide was added dropwise and then was reacted while stirring for 3 hours at 120 C. Formed particles were purified through centrifugation, resulting in CuS nanoparticles. A scanning electron microscope (SEM) image and XRD graph of the formed particles are illustrated in FIGS. 3 and 4.

Manufacturing Example 6

(36) Synthesis of CuS Particles

(37) 80 mL of an ethylene glycol (EG) solution including 5 mmol of Cu(NO.sub.3).sub.2 and 10 mmol of thioacetamide was heated to 100 C. Subsequently, maintaining the temperature, the solution was reacted while stirring for 3 hours. Formed particles were purified through centrifugation, resulting in CuS nanoparticles.

Manufacturing Example 7

(38) Synthesis of CuS Particles

(39) 200 mL of a DEG solution was heated to 120 C. or more and then added dropwise to 50 mL of a DEG solution including 10 mmol of thioacetamide. Subsequently, 50 mL of a DEG solution including 5 mmol of Cu(NO.sub.3).sub.2 was added dropwise thereto. Maintaining the temperature, the solution was reacted while stirring for 3 hours. Formed particles were purified through centrifugation, resulting in CuS nanoparticles.

Manufacturing Example 8

(40) Synthesis of CuS Particles

(41) 250 mL of an EG solution including 5 mmol of Cu(NO.sub.3).sub.2 was heated to 170 C. or more and then 50 mL of an EG solution including 10 mmol of thioacetamide was added dropwise thereto. Subsequently, maintaining the temperature, the solution was reacted while stirring for 3 hours. Formed particles were purified through centrifugation, resulting in CuS nanoparticles. A scanning electron microscope (SEM) image and XRD graph of the formed particles are illustrated in FIGS. 5 and 6.

Manufacturing Example 9

(42) Synthesis of CuS Particles

(43) 250 ml of a DEG solution including 5 mmol of Cu(NO.sub.3).sub.2 was heated to 170 C. or more. Subsequently, 50 mL of a DEG solution including 10 mmol of thioacetamide was added dropwise thereto. Subsequently, maintaining the temperature, the solution was reacted while stirring for 3 hours. Formed particles were purified through centrifugation, resulting in CuS nanoparticles.

Manufacturing Example 10

(44) Synthesis of CuS Particles

(45) 200 mL of a dimethyl formamide (DMF) solution was heated to 120 C. or more and then 50 mL of a DMF solution including 10 mmol of thioacetamide was added dropwise. Subsequently, 50 mL of a DMF solution including 5 mmol of Cu(NO.sub.3).sub.2 was added dropwise and then, maintaining the temperature, the solution was reacted while stirring for 3 hours. Formed particles were purified through centrifugation, resulting in CuS nanoparticles.

Manufacturing Example 11

(46) Synthesis of CuS Particles

(47) 250 mL of an aqueous solution including 5 mmol of Cu(NO.sub.3).sub.2 was heated to 170 C. or more and then 50 ml of an EG solution including 10 mmol of thioacetamide was added dropwise. Subsequently, maintaining the temperature, the solution was reacted while stirring for 3 hours. Formed particles were purified through centrifugation, resulting in CuS nanoparticles.

Manufacturing Example 12

(48) Synthesis of CuS particles

(49) 200 ml of a DEG solution including 3 g of PVP was heated to 120 C. or more and then 50 mL of a DEG solution including 10 mmol of thioacetamide was added dropwise thereto. Subsequently, 50 ml of a DEG solution including 5 mmol of Cu(NO.sub.3).sub.2 was added dropwise and then, maintaining the temperature, the solution was reacted while stirring for 3 hours. Formed particles were purified through centrifugation, resulting in CuS nanoparticles. A scanning electron microscope (SEM) image and XRD graph of the formed particles are illustrated in FIGS. 7 and 8.

Manufacturing Example 13

(50) Synthesis of CuS Particles

(51) 200 mL of a DEG solution including 1 g of dodecylamine was heated to 120 C. or more and then 50 mL of a DEG solution including 10 mmol of thioacetamide was added dropwise thereto. Subsequently, 50 ml of a DEG solution including 5 mmol of Cu(NO.sub.3).sub.2 was added dropwise and then, maintaining the temperature, the solution was reacted while stirring for 3 hours. Formed particles were purified through centrifugation, resulting in CuS nanoparticles. A scanning electron microscope (SEM) image and X-ray diffraction (XRD) graph for the formed particles are illustrated in FIGS. 9 and 10.

Manufacturing Example 14

(52) Synthesis of CuS Particles

(53) To 100 mL of an aqueous solution including 5 mmol of sodium thiosulfate, 100 mL of an aqueous solution including 50 mmol of citric acid was added dropwise and then was heated to 80 C. or more. Subsequently, 50 mL of an aqueous solution including 5 mmol of Cu(NO.sub.3).sub.2 was added dropwise and then, maintaining the temperature, the solution was reacted while stirring for 3 hours. Formed particles were purified through centrifugation, resulting in CuS nanoparticles.

Manufacturing Example 15

(54) Synthesis of CuS Particles

(55) To 100 mL of an EG solution including 5 mmol of sodium thiosulfate, 100 mL of an EG solution including 50 mmol of citric acid was added dropwise and then heated to 80 C. or more. Subsequently, 50 mL of an EG solution including 5 mmol of Cu(NO.sub.3).sub.2 was added dropwise thereto. Subsequently, maintaining the temperature, the solution was reacted while stirring for 3 hours. Formed particles were purified through centrifugation, resulting in CuS nanoparticles.

Manufacturing Example 16

(56) Synthesis of CuS Particles

(57) 100 mL of an EG solution including 5 mmol of thiourea was heated to 80 C. or more and then 100 mL of an EG solution including 5 mmol of Cu(NO.sub.3).sub.2 was added dropwise. Subsequently, maintaining the temperature, the solution was reacted while stirring for 3 hours. Formed particles were purified through centrifugation, resulting in CuS nanoparticles.

Manufacturing Example 17

(58) Synthesis of CuS-Core-ZnS-Shell Nanoparticles

(59) To 5 mmol of CuS nanoparticles synthesized according to Example 5, 100 ml of a DEG solution including 10 mmol of thioacetamide and 8 mmol of ZnCl.sub.2 was added dropwise at room temperature. The resulting solution was heated to 80 C. or more and, maintaining the temperature, stirred for 3 hours. Subsequently, the formed particles were purified through centrifugation. As a result, ZnS shells were formed on surfaces of the CuS nanoparticles. Scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the formed particles are illustrated in FIGS. 11 and 12.

Manufacturing Example 18

(60) Synthesis of CuS-Core-ZnS-Shell Nanoparticles

(61) 100 mL of a DEG solution including 5 mmol of CuS nanoparticles synthesized according to Example 12 was heated to 80 C. or more and then 50 mL of a DEG solution including 16 mmol of thioacetamide and 50 mL of a DEG solution including 8 mmol of ZnCl.sub.2 were added dropwise thereto. Subsequently, maintaining the temperature, the resulting mixture was stirred for 3 hours. Formed particles were purified through centrifugation. As a result, ZnS shells were formed on surfaces of the CuS nanoparticles. Scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the formed particles are illustrated in FIGS. 13 and 14.

Manufacturing Example 19

(62) Synthesis of CuS-Core-ZnS-Shell Nanoparticles

(63) To 5 mmol of CuS nanoparticles synthesized according to Example 12, 150 ml of a DEG solution including 16 mmol of thiourea and 8 mmol of Zn(OAc).sub.2 was added dropwise. The resulting solution was heated to 150 C. or more and, maintaining the temperature, stirred for 3 hours. Subsequently, the formed particles were purified through centrifugation. As a result, ZnS shells were formed on surfaces of the CuS nanoparticles.

Manufacturing Example 20

(64) Synthesis of CuS-Core-ZnS-Shell Nanoparticles

(65) 100 mL of a DEG solution including 16 mmol of thioacetamide was added to 5 mmol of CuS nanoparticles synthesized according to Example 13 and then was heated to 100 C. or more. Subsequently, 50 mL of a DEG solution including 8 mmol of ZnCl.sub.2 was added dropwise thereto. Subsequently, maintaining the temperature, the resulting mixture was stirred for 3 hours. Formed particles were purified through centrifugation. As a result, ZnS shells were formed on surfaces of the CuS nanoparticles. Scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the formed particles are illustrated in FIGS. 15 and 16.

Manufacturing Example 21

(66) Synthesis of CuS-Core-ZnS-Shell Nanoparticles

(67) 100 mL of a DEG solution including 16 mmol of thiourea was added to 5 mmol of CuS nanoparticles synthesized according to Example 13 and then was heated to 100 C. or more. Subsequently, 50 mL of a DEG solution including 8 mmol of Zn(OAc).sub.2 was added dropwise thereto. Subsequently, maintaining the temperature, the resulting mixture was stirred for 3 hours. Formed particles were purified through centrifugation. As a result, ZnS shells were formed on surfaces of the CuS nanoparticles.

Manufacturing Example 22

(68) Synthesis of Cu.sub.6Sn.sub.5 Particles

(69) Under a nitrogen atmosphere, 200 mL of an aqueous solution, in which 150 mmol of NaBH.sub.4 was dissolved, was strongly stirred while slowly adding dropwise 100 mL of an aqueous solution including 10 mmol of SnCl.sub.2 and 12 mmol of CuCl.sub.2. The resulting solution was reacted for 8 hours or more. Formed particles were purified through centrifugation. As a result, nanoparticles having a Cu.sub.6Sn.sub.5 composition were obtained. Scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the formed particles are illustrated in FIGS. 17 and 18.

Example 1

(70) Manufacturing Thin Film Using CuS-Core-ZnS-Shell Nanoparticles and Cu.sub.6Sn.sub.5 Nanoparticles

(71) CuS-core-ZnS-Shell nanoparticles manufactured according to Manufacturing Example 17 and Cu.sub.6Sn.sub.5 particles manufactured according to Manufacturing Example 22 were mixed. The resulting mixture was dispersed in an alcohol based solvent to manufacture an ink. Subsequently, the ink was coated on a glass substrate coated with molybdenum (Mo). The coated layer was dried and then heated with the glass substrate deposited with Se during rapid thermal annealing (RTA) at 575 C. so as to provide a Se atmosphere. As a result, a CZTSSe based thin film was manufactured. A scanning electron microscope (SEM) image and an X-ray diffraction (XRD) graph of the obtained thin film are illustrated in FIGS. 19 and 20.

Example 2

(72) Manufacturing Thin Film Using CuS-Core-ZnS-Shell Nanoparticles and Cu.sub.6Sn.sub.5 Nanoparticles

(73) CuS-core-ZnS-Shell nanoparticles manufactured according to Manufacturing Example 19 and Cu.sub.6Sn.sub.5 particles manufactured according to Manufacturing Example 22 were mixed. The resulting mixture was dispersed in a solvent consisting of an alcohol based solvent to manufacture an ink. Subsequently, the ink was coated on a glass substrate coated with molybdenum (Mo). The coated layer was dried and then heated with the glass substrate deposited with Se during rapid thermal annealing (RTA) at 575 C. so as to provide a Se atmosphere. As a result, a CZTSSe based thin film was manufactured. A scanning electron microscope (SEM) image and an X-ray diffraction (XRD) graph of the obtained thin film are illustrated in FIGS. 21 and 22.

Comparative Example 1

(74) Manufacturing Thin Film Using CuS, ZnS Nanoparticles and Cu.sub.6Sn.sub.5 Nanoparticles

(75) CuS nanoparticles and ZnS nanoparticles were synthesized respectively. The synthesized CuS and ZnS nanoparticles were mixed with Cu.sub.6Sn.sub.5 particles manufactured according to Manufacturing Example 22 and then were dispersed in an alcohol based mix solvent to manufacture an ink. The ink was coated on a glass substrate coated with molybdenum (Mo). The coated layer was dried and then heated with the glass substrate deposited with Se during rapid thermal annealing (RTA) at 575 C. so as to provide a Se atmosphere. As a result, a CZTSSe based thin film was manufactured. A scanning electron microscope (SEM) image of the obtained thin film is illustrated in FIGS. 23A-23D.

Experimental Example 1

(76) Electron microscope images of thin films of Examples 1 and 2, and Comparative Example 1 were analyzed.

(77) Referring to FIGS. 19, 21 and 23, a CZTSSe based thin film manufactured by using the ink composition according to the present invention showed more uniform composition and higher layer density, when compared to a film manufactured by an ink composition in which CuS nanoparticles and ZnS nanoparticles separately manufactured and then mixed. Such results are because oxidation of Cu and Zn is prevented and particles having a desired size are formed, and, accordingly, uniform mixing with nanoparticles including Sn may be easily performed and a uniform composition may be performed in a several hundred nanometer area.

(78) 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.

INDUSTRIAL APPLICABILITY

(79) As described above, according to the present invention, by manufacturing a light absorption layer using core-shell structure nanoparticles including a core including a copper (Cu)-containing chalcogenide and a shell including a zinc (Zn)-containing chalcogenide with tin (Sn)-containing bimetallic or intermetallic metal nanoparticles, or a tin (Sn)-containing chalcogenide nanoparticles, process costs may be reduced and stable processes are possible, and, as such, productivity may be increased.

(80) In addition, the core-shell structure nanoparticles are stable against oxidation and have high reactivity. Thus, a light absorption layer for CZTS based solar cells having a superior quality film may be grown. As a result, photoelectric efficiency of a solar cell according to the present invention is increased.