Method of fabricating A(C)IGS based thin film using Se-Ag2Se core-shell nanoparticles, A(C)IGS based thin film fabricated by the same, and tandem solar cells including the A(C)IGS based thin film

Abstract

A method of fabricating an Ag(Cu)InGaSe (A(C)IGS) based thin film using SeAg.sub.2Se core-shell nanoparticles, an A(C)IGS based thin film fabricated by the method, and a tandem solar cell having the A(C)IGS thin film are disclosed. More particularly, a method of fabricating a densified Ag(Cu)InGaSe (A(C)IGS) based thin film by non-vacuum coating a substrate with a slurry containing SeAg.sub.2Se core-shell nanoparticles, an A(C)IGS based thin film fabricated by the method, and a tandem solar cell including the A(C)IGS based thin film are disclosed. According to the present invention, an A(C)IGS based thin film including Ag is manufactured by applying SeAg.sub.2Se core-shell nanoparticles in a process of manufacturing a (C)IGS thin film, thereby providing an A(C)IGS based thin film having a wide band gap.

Claims

1. A method of fabricating an Ag(Cu)InGaSe (A(C)IGS) based thin film, comprising: step (a) preparing a slurry by blending SeAg.sub.2Se core-shell nanoparticles, multi-component nanoparticles containing at least one element selected from the group consisting of Cu, In, Ga, Se and S, a solution precursor containing at least one element selected from the group consisting of Cu, In, Ga, Se and S, an alcohol solvent, and a binder; step (b) non-vacuum coating a substrate with the slurry to form an A(C)IGS thin film; and step (c) heat-treating the A(C)IGS thin film formed on the substrate for selenization, wherein the SeAg.sub.2Se core-shell nanoparticles have a structure in which a core of Se is surrounded by Ag.sub.2Se, wherein the multi-component nanoparticles are binary, ternary, or quaternary nanoparticles, and wherein the binder comprises at least one selected from the group consisting of a chelating agent and a non-chelating agent.

2. The method according to claim 1, wherein the multi-component nanoparticles comprises at least one kind of nanoparticles selected from the group consisting of: CuSe nanoparticles, InSe nanoparticles, GaSe nanoparticles, CuS nanoparticles, InS nanoparticles, GaS nanoparticles, CuInSe nanoparticles, CuGaSe nanoparticles, InGaSe nanoparticles, CuInS nanoparticles, CuGaS nanoparticles, InGaS nanoparticles, CuInGaSe nanoparticles, and CuInGaS nanoparticles.

3. The method according to claim 1, wherein the multi-component nanoparticles are prepared by any one of methods including a low-temperature colloidal method, a solvothermal synthesis method, a microwave method, and an ultrasonic synthesis method.

4. The method according to claim 1, wherein the solution precursor comprises at least one element selected from the group consisting of Cu, In, Ga, Se, and S, other than the elements contained in the multi-component nanoparticles.

5. The method according to claim 1, wherein the solution precursor comprises at least one selected from the group consisting of indium acetate and gallium acetylacetonate.

6. The method according to claim 1, wherein the alcohol solvent comprises at least one selected from the group consisting of ethanol, methanol, pentanol, propanol, and butanol.

7. The method according to claim 1, wherein the chelating agent comprises at least one selected from the group consisting of monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), ethylenediamine, ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), hydroxyethylenediaminetriacetic acid (HEDTA), glycol-bis(2-aminoethylether)-N,N, N,N-tetraacetic acid (GEDTA), triethylenetetraaminehexaacetic acid (TTHA), hydroxyethyliminodiacetic acid (HIDA), and dihydroxyethylglycine (DHEG).

8. The method according to claim 1, wherein the non-chelating agent comprises at least one selected from the group consisting of ethylene glycol, propylene glycol, ethylcellulose, and polyvinyl pyrrolidone.

9. The method according to claim 1, wherein step (a) further comprises ultrasonication for mixing and dispersion of the slurry.

10. The method according to claim 1, wherein the non-vacuum coating of step (b) is performed by any one method selected from spraying, ultrasonic spraying, spin coating, doctor blade coating, screen-printing, and inkjet printing.

11. The method according to claim 1, wherein step (b) further comprises drying after the non-vacuum coating is performed.

12. The method according to claim 1, wherein step (b) comprises sequentially and repeatedly coating and drying a plurality of times.

13. The method according to claim 1, wherein step (c) is carried out at a substrate temperature ranging from 450 C. to 500 C. for 10 to 30 minutes.

Description

DESCRIPTION OF DRAWINGS

(1) The above and other objects, features, and advantages of the present invention will become apparent from the detailed description of the following embodiments in conjunction with the accompanying drawings, in which:

(2) FIG. 1 is a schematic view of SeAg.sub.2Se core-shell nanoparticles prepared in Preparative Example 7;

(3) FIG. 2 is a SEM image of the SeAg.sub.2Se core-shell nanoparticles prepared in Preparative Example 7;

(4) FIG. 3 is an XRD analysis result of the SeAg.sub.2Se core-shell nanoparticles prepared in Preparative Example 7;

(5) FIG. 4 shows a surface image of an ACIGS thin film prepared in Example 1 (before heat treatment for selenization);

(6) FIG. 5 shows a surface image of an ACIGS thin film after heat treatment for selenization;

(7) FIG. 6 shows a surface image of an ACIGS thin film prepared in Example 2; and

(8) FIG. 7 shows a surface image of an ACIGS thin film prepared in Example 3.

MODE FOR INVENTION

(9) Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood that the present invention is not limited to the following embodiments and may be embodied in different ways. In addition, it should be understood that the following embodiments are provided for complete disclosure and thorough understanding of the invention by those skilled in the art. Thus, the present invention should not be limited by the following embodiments.

Preparative Example 1: Preparation of CuSe Binary Nanoparticle

(10) 7.618 g of CuI was mixed with 60 ml of distilled pyridine solvent in a glove box, followed by mixing with 3.1216 g of Na.sub.2Se dissolved in 40 ml of distilled methanol. By this process, an atomic ratio of Cu:Se of 1:1 was obtained. Thereafter, the mixture of methanol and pyridine was mechanically stirred and reacted in an ice bath at 0 C. for 7 minutes to prepare a colloid containing CuSe nanoparticles. The colloid was subjected to centrifugation at 10,000 rpm for about 10 minutes and then ultrasonication for 1 minute, followed by washing with distilled methanol. This process was repeated to completely remove pyridine and by-products from the resulting material, thereby preparing high-purity CuSe binary nanoparticles.

Preparative Example 2: Preparation of InSe Binary Nanoparticle

(11) 4.9553 g of InI.sub.3 was mixed with 30 ml of distilled tetrahydrofuran solvent in a glove box, followed by mixing with 1.874 g of Na.sub.2Se dissolved in 20 ml of distilled methanol. By this process, an atomic ratio of In:Se of 2:3 was obtained. Thereafter, the mixture of methanol and pyridine was mechanically stirred and reacted in an ice bath at 0 C. for 7 minutes to prepare a colloid containing InSe nanoparticles. The colloid was subjected to centrifugation at 10,000 rpm for about 10 minutes and then ultrasonication for 1 minute, followed by washing with distilled methanol. This process was repeated to completely remove pyridine and by-products from the resulting material, thereby preparing high-purity InSe binary nanoparticles.

Preparative Example 3: Preparation of GaSe Binary Nanoparticle

(12) 4.5044 g of GaI.sub.3 was mixed with 30 ml of distilled tetrahydrofuran solvent in a glove box, followed by mixing with 1.874 g of Na.sub.2Se dissolved in 20 ml of distilled methanol. By this process, an atomic ratio of Ga:Se of 2:3 was obtained. Thereafter, the mixture of methanol and pyridine was mechanically stirred and reacted in an ice bath at 0 C. for 7 minutes to prepare a colloid containing GaSe nanoparticles. The colloid was subjected to centrifugation at 10,000 rpm for about 10 minutes and then ultrasonication for 1 minute, followed by washing with distilled methanol. This process was repeated to completely remove pyridine and by-products from the resulting material, thereby preparing high-purity GaSe binary nanoparticles.

Preparative Example 4: Preparation of InS Binary Nanoparticle

(13) 4.9553 g of InI.sub.3 was mixed with 30 ml of distilled tetrahydrofuran in a glove box, followed by mixing with 1.874 g of Na.sub.2S dissolved in 20 ml of distilled methanol. By this process, an atomic ratio of In:S of 2:3 was obtained. Thereafter, the mixture of methanol and pyridine was mechanically stirred and reacted in an ice bath at 0 C. for 7 minutes to prepare a colloid containing InS nanoparticles. The colloid was subjected to centrifugation at 10,000 rpm for about 10 minutes and then ultrasonication for 1 minute, followed by washing with distilled methanol. This process was repeated to completely remove pyridine and by-products from the resulting material, thereby preparing high-purity InS binary nanoparticles.

Preparative Example 5: Preparation of CuInSe Ternary Nanoparticle

(14) 0.343 g of CuI and 0.991 g of InI.sub.3 were mixed with 30 ml of distilled pyridine solvent in a glove box, followed by stirring on a hot plate of 50 C. for about 10 minutes. After stirring for about 10 minutes, the opaque solution became transparent. The mixture of Cu and In was mixed with 0.5 g of Na.sub.2Se dissolved in 20 ml of distilled methanol. By this process, an atomic ratio of Cu:In:Se of 0.9:1:2 was obtained. Thereafter, the mixture of methanol and pyridine was mechanically stirred and reacted in an ice bath at 0 C. for 1 minute to prepare a colloid containing CIS nanoparticles. The colloid was subjected to centrifugation at 4,000 rpm for about 30 minutes and then ultrasonication for 5 minutes, followed by washing with distilled methanol. This process was repeated to completely remove pyridine and by-products from the resulting material, thereby preparing high-purity CIS compound nanoparticles.

Preparative Example 6: Preparation of CuInGaSe 4-Component Nanoparticle

(15) 0.343 g of CuI, 0.674 g of InI.sub.3, and 0.207 g of GaI.sub.3 were mixed with 30 ml of distilled pyridine solvent in a glove box, followed by stirring on a hot plate of 80 C. for about 10 minutes. After stirring for about 10 minutes, the opaque solution became transparent. The mixture of Cu, In, and Ga was mixed with 0.478 g of Na.sub.2Se dissolved in 20 ml of distilled methanol. By this process, an atomic ratio of Cu:In:Ga:Se of 0.9:0.68:0.23:1.91 was obtained. Thereafter, the mixture of methanol and pyridine was mechanically stirred and reacted in an ice bath at 0 C. for 60 minutes to prepare a colloid containing CIGS nanoparticles. The colloid was subjected to centrifugation at 4,000 rpm for about 30 minutes and then ultrasonication for 5 minutes, followed by washing with distilled methanol. This process was repeated to completely remove pyridine and by-products from the resulting material, thereby preparing high-purity 4-component CIGS nanoparticles.

Preparative Example 7: Preparation of SeAg2Se Core-Shell Nanoparticle

(16) Selenious acid (H.sub.2SeO.sub.3, 99.999%), hydrazine monohydrate (N.sub.2H.sub.4.H.sub.2O, 98%), and poly(vinyl pyrrolidone) (PVP, MW=55000) were purchased from Aldrich Corporation. Ethylene glycol (HOCH.sub.2CH.sub.2OH; EG; 99.9%) was purchased from Fluka Corporation. In a 250 ml round bottom flask, 80 ml of ethylene glycol (EG) was added to a hydrazine hydrate solution prepared using an ethylene glycol solvent (20 ml, 0.7 M) and then left in a water bath at 15 C. to 20 C. Thereafter, the resulting solution was stirred for 10 minutes by a magnet-stirring device and 20 ml of a selenious acid solution (0.07 M, solvent: EG) was added thereto and reacted for 1 hour. Thereafter, a PVP solution (2.4 g PVP and 80 ml EG) was added thereto. After hydrazine was completely removed through vacuum distillation, an AgNO.sub.3 solution (0.1 g AgNO.sub.3 and 1.5 ml EG) was added dropwise over 10 minutes, so that the solution changed from bright red to dark brown. After performing the reaction for 2 hours, 210 ml of water was added to the mixed solution, which were subjected to centrifugation to obtain core-shell nanoparticles. Thereafter, the nanoparticles were washed four times with water to remove EG and an excess of PVP. Then, the nanoparticles were dried through evaporation under ambient conditions, thereby preparing SeAg.sub.2Se core-shell nanoparticles (see FIG. 1).

Example 1: Fabrication of ACIGS Thin Film

(17) 0.0758 g of the SeAg.sub.2Se core-shell nanoparticles prepared in Preparative Example 7, 0.11233 g of the InS nanoparticles prepared in Preparative Example 4, 0.0328 g of the CuSe nanoparticles prepared in Preparative Example 1, 1.9571 g of methanol, 0.0856 g of gallium acetylacetonate as a Ga solution precursor with an MEA solvent, and 0.1391 g of MEA (binder) were mixed, followed by ultrasonication for 60 minutes to prepare an ACIGS slurry. Here, the amount of methanol may be controlled for regulation of viscosity.

(18) Thereafter, a soda-lime glass substrate having a Mo thin film was coated with the slurry by doctor-blade coating. Here, coating was performed with heights of the substrate and the blade set to 50 micrometers. For removal of the solvent and the binder, 3-step drying (1.sup.st step: 80 C. for 5 min; 2.sup.nd step: 120 C. for 5 min; 3.sup.rd step: 200 C. for 5 min) was performed on a hot plate. Here, drying may be performed under different temperature conditions so long as the solvent and the binder can be removed. Coating and drying were repeated three times to form a 0.509 m thick precursor thin film.

(19) Finally, heat treatment for selenization was performed for 15 minutes while supplying Se vapor at a substrate temperature of 450 C., thereby forming an ACIGS thin film.

Example 2

(20) An ACIGS thin film was fabricated in the same manner as in Example 1, except that heat treatment for selenization was performed for 60 minutes while supplying Se vapor at a substrate temperature of 530 C.

Example 3

(21) An ACIGS thin film was fabricated in the same manner as in Example 1, except that heat treatment for selenization was performed for 10 minutes while supplying Se vapor at a substrate temperature of 530 C.

Example 4: Fabrication of AIGS Thin Film

(22) 0.1050 g of the SeAg.sub.2Se core-shell nanoparticles prepared in Preparative Example 7, 0.1470 g of the InS nanoparticles prepared in Preparative Example 4, 1.3708 g of methanol, 0.1405 g of gallium acetylacetonate as a Ga solution precursor with an MEA solvent, and 0.1928 g of MEA (binder) were mixed, followed by ultrasonication for 60 minutes to prepare an AIGS slurry. Here, the amount of methanol may be controlled for regulation of viscosity.

(23) Thereafter, a soda-lime glass substrate having a Mo thin film was coated with the slurry by doctor-blade coating. Here, coating was performed with heights of the substrate and the blade set to 50 micrometers. For removal of the solvent and the binder, 3-step drying (1.sup.st step: 80 C. for 5 min; 2.sup.nd step: 120 C. for 5 min; 3.sup.rd step: 200 C. for 5 min) was performed on a hot plate. Here, drying may be performed under different temperature conditions so long as the solvent and the binder can be removed. Coating and drying were repeated three times to form a 0.787 m thick precursor thin film.

(24) Finally, heat treatment for selenization was performed for 15 minutes while supplying Se vapor at a substrate temperature of 450 C., thereby forming an AIGS thin film.

Experimental Example 1: SEM Image Analysis

(25) SEM (Scanning Electron Microscope) analysis results for SeAg.sub.2Se core-shell nanoparticles according to Preparative Example 7, are shown in FIG. 2. The results demonstrate that homogeneous core-shell particles having a particle size of 370 nm to 380 nm were formed.

Experimental Example 2: XRD Analysis

(26) XRD analysis results for SeAg.sub.2Se core-shell nanoparticles according to Preparative Example 7 analyzed by X-ray diffraction are shown in FIG. 3. Since Se and Ag.sub.2Se peaks are observed, it can be seen that Se, rather than binary nanoparticles is present. That is, in the case of the SeAg.sub.2Se core-shell nanoparticles, since Se itself is present in the core-shell structure, not in the form of a binary or ternary compound, but as a core, Se diffuses from the structure upon initiation of the process, so that the fabrication process can be performed at low process temperature when using the SeAg.sub.2Se core-shell nanoparticles.

Experimental Example 3: Surface Characteristics of ACIGS Thin Film

(27) FIG. 4 shows a surface image of the ACIGS thin film prepared in Example 1 (before heat treatment for selenization), FIG. 5 shows a surface image of the ACIGS thin film after heat treatment for selenization, FIG. 6 shows a surface image of the ACIGS thin film prepared in Example 2, and FIG. 7 shows a surface image of the ACIGS thin film prepared in Example 3. The results demonstrate that the thin film (FIG. 5) of Example 1, in which heat treatment for selenization was performed for 15 minutes at 450 C., had the most compacted structure.

(28) Although some embodiments have been described above, it should be understood that these embodiments are given by way of illustration only, and that various modifications, variations, and alterations can be made without departing from the spirit and scope of the present invention. The scope of the present invention should be construed only by the accompanying claims and equivalents thereof.