KR20120100568A - Copper indium selenide nanoparticles and preparing method of the same - Google Patents

Abstract

PURPOSE: Copper indium selenide nano-particles and a method for preparing the same are provided to adjust the sizes and/or the compositions of nano-particles and to mass-produce copper indium selenide nano-particles of uniform sizes. CONSTITUTION: A method for preparing copper indium selenide nano-particles includes the following: a selenium metal is mixed with a first coordinate solvent to be reacted to prepare a selenium precursor solution; a copper precursor and an indium precursor are mixed with a second coordinate solvent to prepare a copper/indium precursor solution; and the selenium precursor solution and the copper/indium precursor solution are mixed and heated to form copper indium selenide nano-particles. The selenium precursor solution preparing process further includes a carbon monoxide introducing process.

Description

Copper indium selenide nanoparticles and its manufacturing method {COPPER INDIUM SELENIDE NANOPARTICLES AND PREPARING METHOD OF THE SAME}

The present invention relates to a method for preparing copper indium selenide nanoparticles capable of producing a large amount of copper indium selenide (CIS) nanoparticles having a uniform size and copper indium selenide nanoparticles produced thereby.

The synthesis of colloidal semiconductor nanocrystals has received a lot of attention over the last few decades because of their unique optical and electrical properties that differ from those of the bulk state. In terms of quantum mechanics, the bandgap of semiconductor nanocrystals can be controlled by varying their size within a size range smaller than the bore diameter. The larger the extinction coefficient per unit volume, the longer the time until the exciton disappears, and the better the fluorescence quantum efficiency (brightness) at room temperature. Over the past two decades, research has been actively conducted to synthesize semiconductor nanocrystals with uniform size within the range where quantum size effects occur. Semiconductor nanocrystals synthesized by liquid phase reaction can be useful for the fabrication of optoelectronic device thin films because the thin films can be easily made by self-assembly, supporting coating, spin coating, inkjet printing, etc. have. From this point of view, synthesizing uniform semiconductor nanocrystals within the range where quantum size effects occur is important for high efficiency electronic devices and solar cell devices. As a result, semiconductor nanocrystals of uniform size made through colloidal liquid reactions are actively studied as a building-block of next generation solar cells as a method for reducing solar cell production costs.

Among thin-film solar cells, solar cells based on indium selenide (CIS) have received great attention because they can achieve high efficiency of up to 19% at the laboratory level. Due to the material's 1.05 eV direct bandgap and its large absorption coefficient within the 1000 nm infrared wavelength range, CIS can be used as a p-type light absorbing layer for thin film solar cells. The 19% high-efficiency CIS-based solar cell is the result of doping some Ga into the CIS. This is because when the Ga is introduced, the band gap of the CIS increases from 1.1 eV to 1.4 eV energy, which is theoretically known to be the most efficient solar cell. In general, using a CIS with a large band gap is good for increasing the efficiency of the module, but has a disadvantage of lowering the current value at the maximum output. The inclusion of more Ga in the CIS layer increases the open voltage and lowers the power conversion efficiency due to the increase in the relationship between voltage and current and recombination of electrons and holes. "Colloid nanoparticle ink" can be a good way to overcome the disadvantages that appear when the amount of Ga in the CIS layer increases. As mentioned earlier, CIS nanoparticles can adjust the bandgap by varying the average size of the particles within a bore diameter of less than 10.4 nm. This suggests the possibility of controlling the electrical characteristics by adjusting the bandgap without adding Ga to the CIS absorbing layer.

Recently, various studies on the synthesis of CIS nanocrystals have been reported. However, these syntheses are not fully complemented in terms of solar cell commercialization. The bandgap of semiconductor nanoparticles should be controlled to have a uniform size distribution within the size range where quantum size effects occur. Furthermore, existing prior research on the method of synthesizing a large amount with a uniform size within such a small size range Has not been reported, and this is an important issue to be solved in solar cell applications.

The present application is to provide a method for producing copper indium selenide nanoparticles that can produce a large amount of copper indium selenide (CIS) nanoparticles having a uniform size and copper indium selenide nanoparticles produced thereby do. Specifically, indium selenide nanoparticles having uniform chalcopyrite crystal structure in the particle size range exhibiting a quantum size effect are prepared by using a low-cost metal precursor and an elevated temperature synthesis method. It is to provide a production method capable of obtaining and control the size and / or composition of the nanoparticles and the copper indium selenide nanoparticles produced thereby.

 However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

A first aspect of the present disclosure can provide a method of preparing copper indium selenide nanoparticles comprising:

Preparing a selenium precursor solution by reacting by adding CO gas to a solution containing selenium (Se) metal and a first coordinating solvent;

Mixing a copper precursor and an indium precursor with a second coordinating solvent to prepare a copper / indium precursor solution; And

Heating the mixed solution in which the selenium precursor solution and the copper / indium precursor solution are mixed to form copper indium selenide (CIS) nanoparticles.

The second aspect of the present application can provide a copper indium selenide nanoparticles prepared by the method according to the present application.

Provided herein is a method for preparing copper indium selenide nanoparticles capable of producing a large amount of copper indium selenide (CIS) nanoparticles having a uniform size, and copper indium selenide nanoparticles produced thereby Can be. Specifically, according to the present invention, uniform selenization by producing a copper indium selenide nanoparticles having a chalcopyrite crystal structure of the particle size range exhibiting a quantum size effect by using a low-cost metal precursor and an elevated temperature synthesis method It is possible to provide a copper indium nanoparticles and also to provide a production method capable of controlling the size and / or composition of the nanoparticles and the copper indium selenide nanoparticles produced thereby. The composition and size of the copper indium selenide nanoparticles can be changed by the manufacturing method of the present application and mass production of copper indium selenide nanoparticles having a uniform size in which a quantum size effect occurs is possible at low cost.

1 is an electron transmission microscopy (TEM) image of copper indium selenide nanoparticles prepared according to one embodiment of the present application: (a) 3.1 nm, (b) 3.9 nm, (c) 4.7 nm, and (d ) Transmission electron microscope (TEM) photograph of 9.1 nm CIS nanocrystals. The attached figures in (a) and (c) are high resolution transmission electron microscope (HR-TEM) images of CIS nanocrystals.
2 is a size distribution histogram of copper indium selenide nanoparticles prepared according to one embodiment of the present application: (a) 3.1 nm, (b) 3.9 nm, (c) 4.7 nm CIS nanocrystals.
3 is an X-ray diffraction (XRD) pattern of copper indium selenide nanoparticles prepared according to one embodiment of the present application: (a) X-ray diffraction (XRD) pattern of CIS nanocrystals (b) Synthesis temperature Lattice constants of CIS nanocrystals according to. a-CuInSe₂(Blue) and b-CuIn₃Se₅The (red) line represents the bulk lattice constant.
4 is an X-ray diffraction (XRD) pattern of copper indium selenide nanoparticles prepared according to one embodiment of the present application: (a) 7.2 nm-copper indium selenide nanocrystals, (b) 17 nm-selenium Indium Copper Nanocrystals. The inserted X-ray diffraction (XRD) pattern shows the crystal plane of Chalccopyrite indium selenide copper 211.
 5 is an absorption (black line) and emission (dark and red line) spectrum of copper indium selenide nanoparticles prepared according to one embodiment of the present application:(a)Absorption (black line) and luminescence (dark and red line) spectra of CIS nanocrystals, (b) energy from the absorption spectrum and (ahu)² 4.7 nanometer-CuIn through extrapolation of graph_{One .3}Se_{2 .6} The bandgap of the nanoparticles was found to be 1.3 eV.
6 is a graph of energy bands of copper indium selenide nanoparticles prepared according to one embodiment of the present application: (a) CuInSe₂  (b) CuIn₃Se₅ Nanocrystals.
7 is copper indium selenide nanoparticles CuInSe prepared according to one embodiment of the present application₂CuIn (thick red line)₃Se₅ Graph showing minimum energy of electrons and holes in (blue line) (dotted line is CuInSe in bulk state)₂(Thick red dotted line) and CuIn₃Se₅ (Thick blue dotted line) electron affinity and ionization energy).
8 is a CuInSe prepared according to one embodiment of the present application₂And CuIn₃Se₅A graph showing a calculated value of the band gap according to the diameter of the nanoparticles of (a) and a comparison graph (b) of the band gap (square point) obtained from the absorption spectrum and the calculated band gap (line).
9 is a photograph showing a large capacity copper indium selenide nanoparticles prepared according to one embodiment of the present application.

DETAILED DESCRIPTION Hereinafter, embodiments and examples of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present disclosure.

It should be understood, however, that the present invention may be embodied in many different forms and is not limited to the embodiments and examples described herein. In the drawings, the same reference numbers are used throughout the specification to refer to the same or like parts.

Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise. The terms "about "," substantially ", etc. used to the extent that they are used throughout the specification are intended to be taken to mean the approximation of the manufacturing and material tolerances inherent in the stated sense, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure.

Throughout this specification, when a layer or member is located “on” with another layer or member, it is not only when a layer or member is in contact with another layer or member, but also between two layers or another member between the two members. Or when another member is present. The word " step (or step) "or" step "used to the extent that it is used throughout the specification does not mean" step for.

A first aspect of the present disclosure can provide a method of preparing copper indium selenide nanoparticles comprising:

Preparing a selenium precursor solution by mixing and reacting a selenium (Se) metal and a first coordinating solvent;

Mixing the copper precursor and the indium precursor with a second coordinating solvent to prepare a copper / indium precursor solution; And

Heating the mixed solution in which the selenium precursor solution and the copper / indium precursor solution are mixed to form copper indium selenide (CIS) nanoparticles.

In one embodiment, in the preparation of the selenium precursor solution, the selenium precursor may be in the form of a complex of Se-first coordinating solvent, but is not limited thereto.

In one embodiment, the preparing of the selenium precursor solution may further include adding CO gas after mixing the selenium (Se) metal and the first coordinating solvent, but is not limited thereto. It doesn't happen. In this case, in the preparing of the selenium precursor solution, the selenium precursor may have a complex form of Se-carbonyl-first coordinating solvent, but is not limited thereto.

The preparing of the copper / indium precursor solution may include mixing the copper precursor and the indium precursor with the second coordinating solvent, followed by moisture and air by vacuum treatment at a temperature of 100 ° C. to 200 ° C. It may include to remove, but is not limited thereto.

In one embodiment, the method for preparing the copper indium selenide nanoparticles according to the present application may be performed by the following reaction scheme using a metal precursor as described above, but is not limited thereto.

By using the metal precursor as described above in the production method of the present application, the difficulty of the method of synthesizing through the solution phase pyrolysis reaction of a single precursor such as (PPh ₃ ) ₂ CuIn (SePh) ₄ and the difficulty of mass production Problems can be solved. For example, in the above-described preparation method of the present invention, if a salt such as a salt of copper and indium (eg, a halogenated salt) and precursors such as selenium metal are directly used, a large amount of copper indium selenide nanoparticles can be easily obtained in an inexpensive manner. Can produce.

 In one embodiment, all of the steps may be performed in an inert gas atmosphere from which air and moisture are removed, but is not limited thereto.

In one embodiment, the CO gas may be added at a temperature of 20 ℃ to 200 ℃, but is not limited thereto.

In one embodiment, the temperature of any one or both of the selenium precursor-containing solution and the copper / indium precursor solution may be mixed in a state of about 20 ℃ to 300 ℃, but is not limited thereto.

In one embodiment, the heating temperature of the mixed solution in which the selenium precursor solution and the copper / indium precursor solution are mixed may be about 20 ° C. to 330 ° C., but is not limited thereto. In one embodiment, the heating rate in the heating process can be adjusted within the range of about 1 ℃ / min to 100 ℃ / min, but is not limited thereto.

In one embodiment, the preparing of the copper / indium precursor solution may include mixing the copper precursor and the indium precursor with the second coordinating solvent, followed by vacuum treatment at a temperature of about 100 ° C. to 200 ° C. It may be to include removing the air, but is not limited thereto.

In one embodiment, the first coordinating solvent may be an amine compound, for example, a primary amine compound may be used, but is not limited thereto. As a non-limiting example of the primary amine compound, oleylamine, octylamine, hexylamine, hexylamine, butylamine, propylamine, aniline, benzylamine (benzylamine), hexadecylamine (hexadecylamine), octadecylamine (octadecylamine) and combinations thereof may be selected from the group consisting of, but is not limited thereto.

In one embodiment, the second coordinating solvent may be one selected from the group consisting of cationic surfactants, neutral surfactants, anionic surfactants, and combinations thereof, but is not limited thereto.

 In one embodiment, the cationic surfactant may include one selected from the group consisting of alkyl trimethylammonium halide, alkyl trimethylammonium hydroxide, and combinations thereof. However, the present invention is not limited thereto.

In one embodiment, the neutral surface active agent is a _{carbon-3 -20} C, which may include a carbon-carbon double bond-alkyl amines; Aromatic amines such as aniline, benzylamine, dibenzylamine, tribenzylamine, diphenylamine, triphenylamine, and the like; Carbon-carbon double bond, C _{3 -20,} which can include carboxylic acid, tri (C _3-20 - alkyl) phosphine oxide, tri (C _3-20 - alkyl) phosphine, triphenylphosphine, C _3-20 -alkyl and thiol, but can be to include those selected from the group consisting of, without being limited thereto.

In one embodiment, the anionic surfactant may include one selected from the group consisting of sodium alkyl sulfate, sodium alkyl phosphate, and combinations thereof, but is not limited thereto. no.

In one embodiment, the C _{3 -20-alkyl} amines, carbon-2, which may include a carbon-carbon double bond-primary amine, an alkyl group having a _{carbon-3 -20} C, which may include a carbon-carbon double bond one which comprises is selected from a tertiary amine having an alkyl group, and the group consisting of-C _{3 -20} - having an alkyl secondary amine, carbon-3 _-20 C ₃ which may include a carbon-carbon double bond May be, but is not limited thereto.

In one embodiment, an amine compound may be used as the second coordinating solvent. For example, a primary amine compound, a secondary amine compound, or a tertiary amine compound may be used, but is not limited thereto. no. Non-limiting examples of the amine-based compound, oleylamine (oleylamine), octylamine (octylamine), hexylamine (hexylamine), butylamine (butylamine), propylamine (Propylamine, hexadecylamine, octadecyl, octadecyl Octadecylamine, dioctylamine, dibenzylamine, dibutylamine, dihexylamine, tri-n-octylamine, trihexylamine n-hexylamine, tri-n-butylamine, oleic acid, alkyl trimethylammonium halide, alkyl trimethylammonium hydroxide, trioctylphosphine oxide TOPO), trioctylphosphine (TOP), tributylphosphine (tributylphosphine), triphenylphosphine, sodium alkyl sulfate, sodium alkyl phosphate, and It may include one selected from the group consisting of a combination thereof, but is not limited thereto.

In one embodiment, each of the copper precursor and the indium precursor may use a halogen salt, hydroxide salt, organic acid salt, or inorganic acid salt, but is not limited thereto.

In one embodiment, the copper precursor and the indium precursor may be to include each independently having the form of a halogen salt, but is not limited thereto. In one embodiment, the copper precursor and the indium precursor may be to include CuI and InI ₃ , respectively, but is not limited thereto.

In one embodiment, the manufacturing method may further include recovering the indium copper selenide nanoparticles formed, but is not limited thereto.

In one embodiment, the step of recovering the indium selenide nanoparticles may include, but is not limited to, precipitating the nanoparticles by adding alcohol or acetone. For example, the alcohol may be appropriately selected from methanol, ethanol, propanol, butanol, and the like, but is not limited thereto.

In one embodiment, the step of recovering the indium selenide nanoparticles, the selenium unreacted by the addition of tri (C _3-20 -alkyl) phosphine or triphenyl phosphine after the nanoparticles are precipitated It may further include dissolving the precursor, but is not limited thereto.

In one embodiment, the step of recovering the indium selenide nanoparticles may further include separating the precipitated nanoparticles by centrifugation, but is not limited thereto.

In one embodiment, the manufacturing method may be to control the size or composition, or size and composition of the copper indium selenide nanoparticles formed, but is not limited thereto.

In one embodiment, the size of the copper indium selenide nanoparticles may be about 2 nm to 100 nm, but is not limited thereto.

The second aspect of the present application can provide a copper indium selenide nanoparticles prepared by the method according to the present application.

In one embodiment, the copper indium selenide nanoparticles may be of a uniform size, but is not limited thereto.

In one embodiment, the size of the copper indium selenide nanoparticles may be about 2 nm to 20 nm, but is not limited thereto.

In one embodiment, the copper indium selenide nanoparticles may have a quantum-confinement regime, but is not limited thereto.

In one embodiment, the copper indium selenide nanoparticles may have a chalcopyrite crystal form having a regular attack point ( vacancy ) ( vacancy ), but is not limited thereto.

In one embodiment, the copper indium selenide nanoparticles _{CuIn 2 .5 Se 4, CuIn 1} .1 Se 2 or having a crystal form but may be a combination thereof, without being limited thereto.

In one embodiment, the copper indium selenide nanoparticles have a lattice distortion due to the attack point (tetragonal distortion = c / 2a, where a and c are lattice constants of the indium selenide crystal) are 0.97 to 1.06 days May be, but is not limited thereto.

The method for producing the copper indium selenide nanoparticles according to the present invention is a uniform size of calcopyrite through a simple temperature rising method based on the acidic reaction of the metal iodide and selenocarbamate within the size range in which the quantum effect occurs ( Copper indium selenide (or copper indium selenide, for short CIS) nanocrystals can be synthesized. Changes in the structure and bandgap of the nanocrystals according to the size and composition of the copper indium selenide nanoparticles prepared by the production method according to the present application can be measured using X-ray diffraction, absorption and emission spectrum analysis. When the size and composition of the copper indium selenide nanoparticles are changed within the size range in which the quantum effect occurs, the expansion of the specific crystal unit and the distortion of the tetragonal system can be confirmed, unlike in the bulk state.

By the method for producing the copper indium selenide nanoparticles according to the present invention can be synthesized in a large amount of the copper indium selenide nanoparticles in grams unit by using it can be applied to the production of low-cost thin film solar cell, other selenium It will be applicable to various electrical / electronic devices using copper indium compound semiconductors.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[ Example ]

Nanoparticle synthesis of about 4.7 nm of copper indium selenide was carried out under argon gas conditions, completely blocking air and moisture in the Schlenk line. Oleammonium selenoid carbamate was added 0.395 g (5 mmol) of selenium powder in 10 mL oleylamine and CO gas was added at 120 ° C. for 2 hours. In the process, the color of the solution gradually changed from reddish brown to transparent color. At the same time 15 mL of oleyl amine was degassed in vacuo at 120 ° C. for 2 hours. After 2 hours, oleylamine was cooled to room temperature. In a glove box, 0.095 g of 0.5 mmol of copper (I) iodide and 0.248 g of 0.5 mmol of indium (III) iodide were added. The reagent solution was vacuumed at 120 ° C. to remove moisture and air for 30 minutes. This process turns the metal-oleyl amine complex into a clear, gold colored solution. The solution is cooled to 70 ° C. with Ar, and 1 mmol (2 mL) of oleyl ammonium seleno carbamate solution is injected. Raise the solution, turned black, to 195 ° C, 12 ° C per minute. After reaching 210 ° C., nanoparticles were grown for 30 minutes at this temperature. In order to compare the temperature effect of the nanoparticle crystal growth, the physical properties of each nanoparticle prepared and obtained at various temperatures ranging from 80 ° C to 300 ° C were compared (see Table 1).

Thereafter, 100 mL of ethyl alcohol is poured to precipitate the synthesized nanoparticles. In addition, 3 mL of trioctylphosphine was added to dissolve the remaining selenium precursors. When precipitated using a centrifuge, black CuInSe ₂ Sediment sinks. 100 mL of ethanol was used to remove the organics one more time. The separated nanoparticles were dispersed in chloroform and used for analysis.

The synthesis scheme of nanoparticles of copper indium selenide in this example is as follows:

The synthesized copper indium selenide nanoparticles were analyzed by various methods using transmission electron microscopy (TEM), X-ray diffraction crystal analysis (XRD) and inductive plasma spectroscopy (ICP-AES). Low and high magnification TEM images were taken using a JEOL EM-2010 EXII microscope. The XRD pattern used a Rigaku D / Max-3C diffractometer and a rotatable anode, Cu Kα radiation source (λ = 0.15418 nm). XRD patterns and crystal constants were obtained using the Pearson-Ⅶ function. Inductively coupled plasma spectra were obtained using the Shimadzu ICPS-7500 to obtain quantitative proportions of the elements. Absorption spectrum was used by JASCO V-570 UV-VIS-NIR spectrometer. Photoluminescence spectra were obtained by activating electrons with a 532 nm laser diode using the Ocean Optics USB 4000 spectrum.

After completion of the synthesis reaction, it was confirmed that the nanoparticles having a uniform size of 3.1 nm having a size distribution of 9% were synthesized by an electron transmission microscope (FIG. 1A). Considering that the bore diameter of copper indium selenide is 10.4 nm, it can be seen that the nanocrystals synthesized in this example are within a range in which a quantum-confinement regime occurs. As a result of determining the ratio of the components through ICP analysis, it was shown as CuIn _2.1 Se _2.6 (Table 1). The size and composition of the nanocrystals were changed by controlling the temperature at which the crystals grow. 80 ^o when the crystal growth temperature in C to 300 ^o C higher, despite the conditions of use of the precursor of the same concentration and composition of the nanocrystals CuIn ₂ Se _{4 .5} in a CuIn _{1 .1 2} Se, the nanocrystal size Changed from 2.5 nm to 17 nm (see FIG. 1, Table 1, FIG. 2).

In the previous studies, it is known that the optical and electrical properties of CIS are highly dependent on the composition and vacancy of the material (regardless of defect-or microcrystalline structure). In this regard, it is very important to understand the change of crystal structure according to the composition of CIS nanocrystals. X-ray diffraction analysis showed that the structure of the nanocrystals is basically a chalcopyrite (chalcopyrite) crystal structure (Fig. 3a). However, it can be seen that the degree of diffraction at the crystal plane (211), which means a regular degree of alignment between the Cu (I) and In (III) cations, is smaller than that of the bulk crystal chalcopyrite structure of the single crystal. (FIG. 4). Thus, it was found that the CIS nanocrystals synthesized in this study were "Chalcopyrite" structures with "regular vacancy." As a next step, we looked at the crystal constants and the degree of tetragonal distortion from a microscopic point of view.

Table 1 shows the crystal lattice constants of the nanocrystals obtained through the X-ray diffraction analysis. As a result, although the composition of the synthesized nanocrystals is between CuIn ₃ Se ₅ and CuInSe ₂ , the values of the crystal lattice constants a and c were larger than those of a-CuInSe ₂ and b-CuIn ₃ Se ₅ . Furthermore, the values of tetragonal distortion to c / 2 a due to the regular vacancy of nanoparticles are in the a-CuInSe ₂ (1.00) and b-CuIn ₃ Se ₅ (0.95) chalcopyrite crystal structures. It came out in the range of 1.03-1.06 larger than the value of. Unusual crystal expansion and lattice distortion in these nanocrystals means that the distortion caused by the voids in the crystal is different from that of the bulk material. In addition, Hugh W. Hillhouse and his colleagues at Purdue University have found that lattice distortion occurs in CuInSe ₂ nanocrystals with a perfect composition without crystal defects of 37 nm in size, using high-resolution transmission electron microscopy.

The growth temperature of the nano-crystals in the process of raising up to 300 ^o C composition approaches the CuIn _{1 .1} Se ₂ value of the lattice distortion (tetragonal distortion) has been confirmed a tendency to gradually decrease to 1.03. This appears to be due to the increase in the size of the nanocrystals at high temperatures and the reduction of crystal lattice stress due to the empty defects of copper atoms. Nevertheless, diffraction by the crystal plane in the nanocrystals of 211 almost complete composition (211) means that the crystal structure is closer to tetragonal chalcopyrite than to sphalerite (Fig. 3, Fig. 4). The grain size of the nanocrystals was obtained by analyzing the X-ray diffraction experiment results by Debye-Scherrer equation. As a result, the grain size of the nanocrystal was 70% to 80% smaller than the value measured in the TEM photograph, which means that the nanocrystal is not a single crystal but is polycrystalline and has many crystal defects.

Absorption of the CIS nanocrystals includes the entire region of visible light, and by controlling the composition and size of the nanocrystals, absorption and bandgap in the near infrared region can be controlled (FIGS. 5 and 6). Clearly appearing in the absorption spectrum of the nanocrystals (dinstinct shoulder) means that the size distribution of the nanocrystals is uniform. The emission spectrum of the nanocrystals as well as the emission spectrum (Photoluminescence-PL) were also able to control the emission wavelength within the 800nm to 900nm wavelength range (Fig. 5a). Irrespective of the composition of the synthesized nanocrystals, the direct bandgap obtained from the absorption and emission spectra of the nanocrystals is a-CuInSe ₂ (1.0 eV) and b-CuIn ₃ Se ₅ (1.2 eV). It was confirmed that the shift to the shorter wavelength region than () (Fig. 5b). Therefore, a strong quantum size effect is observed in the synthesized nanocrystals of 2 nm to 5 nm, which is considered to have the biggest influence on the change of the band gap (see Table 2).

On the other hand, since the composition and defects of nanocrystals are expected to exhibit a statistical distribution, the emission spectrum is wider than that of II-VI or IV-VI semiconductor nanocrystals despite the uniform size of the particles. The distribution of bands is shown. If the reaction temperature is higher than 200 ℃ Ostwald ripening (Ostwald ripening) occurs, the size uniformity of the particles are reduced, the shape of the emission spectrum loses the symmetry, the luminous efficiency is also reduced. In addition, even when the precursor was changed to metal chlorides such as copper (I) and indium (III) chloride instead of metal iodide under the same experimental conditions, the crystal structure and composition of the nanoparticles showed similar tendency. . However, the overall luminous efficiency was reduced than when using metal iodide precursors.

It is very important to know the relationship between the composition of the nanocrystals and the direct band gap within the range where strong quantum size effects occur. In that sense, the bandgaps measured through experiments were analyzed using a theoretical model within a spherical limited energy barrier (Fig. 7). The wave function of the CIS consists of the combination of the spherical Bessel function, the Neumann function, and the Hekell function of the organic ligand. Where R (r) is the radial eigenfunction and R _o is the radius of the quantum dot.

In this example, the effective masses of the electrons and holes of CuInSe ₂ are 0.09 and 0.076, respectively, and 0.16 and 1.1 in CuIn ₃ Se ₅ , respectively. The effective masses of the electrons and holes of the organic ligands were 3.03 and 0.3, respectively. The values of electron affinity and ionization energy were -4.3 eV and 5.3 4 eV for CuInSe ₂ , -3.99 eV and -5.18 eV for CuIn ₃ Se ₅ , and -1.5 eV and -11.8 eV for organic ligands.

In the bulk state, the bandgap (1.2 eV) of CuIn ₃ Se ₅ is larger than the bandgap of CuInSe ₂ , but the theoretical model calculations show that in CuInSe ₂ , the bandgap changes due to the small effective electron-hole mass. Depends more on (FIG. 8A). And the difference between the calculated band gap of CuIn ₃ Se ₅ and CuInSe ₂ of 2 nm to 3 nm size was small as 30 meV to 90 meV. The previous calculations suggest that the quantum size effect is the major factor in changing the bandgap, rather than the composition, within the range in which this effect occurs. In addition, it is noteworthy that the bandgap of the nanocrystals is closer to CuInSe ₂ than to CuIn ₃ Se ₅ (FIG. 8B).

The use of precursors and low reaction temperatures readily available by one embodiment of the present application makes the synthesis process very reproducible and also allows for mass production. For example, the reaction was scaled up to 13 times, resulting in 1.3 g of CIS nanoparticles synthesized in one experimental vessel (FIG. 9).

In summary, according to one embodiment of the present application, a new method for synthesizing CIS nanocrystals having a quantum size effect capable of changing composition and size has been developed. By varying the composition and size of the nanocrystals within the range where strong quantum size effects occur, unique crystal expansion and lattice distortion, which were different from those in the bulk state, were confirmed. Within the size range of synthesized nanocrystals, it was also found that the bandgap of nanocrystals was influenced by particle size rather than composition. Finally, using this synthesis method, mass production at gram scale is possible, and the possibility of application as an inexpensive solar cell device is also presented. Since the crystal structure and crystal defects of CIS are closely related to optical and electrical properties, the optical and electrical properties of CIS nanocrystals may be different from those in the bulk state.

Hereinbefore, the present invention has been described in detail with reference to the embodiments and examples, but the present invention is not limited to the above embodiments and embodiments, and may be modified in various forms, and is commonly used in the art within the technical spirit of the present application. It is evident that many variations are possible by those of skill in the art.

Claims (33)

Preparing a selenium precursor solution by mixing and reacting a selenium (Se) metal and a first coordinating solvent;
Mixing the copper precursor and the indium precursor with a second coordinating solvent to prepare a copper / indium precursor solution; And
Heating the mixed solution in which the selenium precursor solution and the copper / indium precursor solution are mixed to form copper indium selenide (CIS) nanoparticles:
A method of producing a copper selenide indium nanoparticles comprising a.
The method of claim 1,
The preparing of the selenium precursor solution may further include adding CO gas after mixing the selenium (Se) metal and the first coordinating solvent.
The method of claim 1,
Wherein the selenium precursor comprises a complex form of Se- first coordinating solvent, method of producing copper indium selenide nanoparticles.
The method of claim 2,
Wherein the selenium precursor comprises a complex form of Se-carbonyl-first coordinating solvent.
The method of claim 1,
The preparing of the copper / indium precursor solution may include mixing the copper precursor and the indium precursor with the second coordinating solvent to remove moisture and air by vacuum treatment at a temperature of 100 ° C. to 200 ° C. That is, the manufacturing method of the indium copper selenide nanoparticles.
The method of claim 1,
All the above steps are carried out in an inert gas atmosphere from which air and moisture are removed, the manufacturing method of the indium copper selenide nanoparticles.
The method of claim 2,
The CO gas is added at a temperature of 20 ° C to 200 ° C, a method for producing indium copper selenide nanoparticles.
The method of claim 1,
Any one or both of the selenium precursor-containing solution and the copper / indium precursor solution is mixed at a temperature of 20 ° C to 300 ° C, the method for producing copper indium selenide nanoparticles.
The method of claim 1,
The heating temperature of the mixed solution which mixed the said selenium precursor solution and the said copper / indium precursor solution is 20 degreeC-330 degreeC, The manufacturing method of the indium copper selenide nanoparticles.
The method of claim 1,
The first coordinating solvent is a method of producing a copper indium selenide nanoparticles containing a primary amine compound.
11. The method of claim 10,
The primary amine compound may be oleylamine, octylamine, hexylamine, hexylamine, butylamine, propylamine, aniline, benzylamine, hexa Hexadecylamine, octadecylamine (octadecylamine) and a combination comprising those selected from the group consisting of, a method for producing copper indium selenide nanoparticles.
The method of claim 1,
Wherein the second coordinating solvent is selected from the group consisting of cationic surfactants, neutral surfactants, anionic surfactants and combinations thereof, the method for producing copper indium selenide nanoparticles.
The method of claim 12,
The cationic surfactants include those selected from the group consisting of alkyl trimethylammonium halides, alkyl trimethyl ammonium hydroxides, and combinations thereof. Method of Making Particles.
The method of claim 12,
The mild surfactant is a carbon-carbon double bond, which may include C _{3 -20} - - alkylamine, aromatic amine, carbon ,, - C _{3 -20,} which may include a carbon-carbon double bond acid, tri (C _{3 -20-alkyl)} phosphine oxide, tri (C _3-20 -alkyl) phosphine, triphenylphosphine, C _{3 -20-a} comprises is selected from the group consisting of alkyl thiol and a combination thereof, selenium Method for producing copper indium sulfide nanoparticles.
The method of claim 12,
Wherein the anionic surfactant is selected from the group consisting of sodium alkyl sulfate (sodium alkyl sulfate), sodium alkyl phosphate (sodium alkyl phosphate), and combinations thereof, a method for producing copper indium selenide nanoparticles.
15. The method of claim 14,
The C _{3 -20-alkyl} amines, carbon-primary amine, an alkyl group having a carbon-carbon double bond, C _{3 -20,} which may include a two-to-carbon double bond include C _{3 -20-alkyl} with a secondary amine, carbon-3 _-20 C ₃ which may include a carbon-carbon double bond-tertiary amine having an alkyl group, and which comprises is selected from the group consisting of, copper indium selenide Method for producing nanoparticles.
The method of claim 1,
The second coordinating solvent is oleylamine (oleylamine), octylamine (octylamine), hexylamine (hexylamine), butylamine (butylamine), propylamine (propylamine), aniline (aniline), benzylamine (benzylamine), dibenzyl Amines, tribenzylamine, diphenylamine, triphenylamine, hexadecylamine, octadecylamine tri-n-octylamine, tri-n-hexylamine, tri Tri-n-butylamine, oleic acid, alkyl trimethylammonium halide, alkyl trimethylammonium hydroxide, trioctylphosphine oxide (TOPO), trioctyl Composed of trioctylphosphine (TOP), tributylphosphine, triphenylphosphine, sodium alkyl sulfate, sodium alkyl phosphate, and combinations thereof A method for producing a copper indium selenide nanoparticles comprises is selected from the group.
The method of claim 1,
The copper precursor and the indium precursor are each independently a halogen salt, a hydroxide salt, an organic acid salt, or an inorganic acid salt, a method for producing copper indium selenide nanoparticles.
The method of claim 18,
The copper precursor and the indium precursor each independently comprises a halogenated salt, a method for producing copper indium selenide nanoparticles.
The method of claim 19,
The copper precursor and the indium precursor are each independently comprising a iodide salt, a method for producing copper indium selenide nanoparticles.
The method of claim 1,
Further comprising the step of recovering the formed copper indium selenide nanoparticles, method for producing copper indium selenide nanoparticles.
22. The method of claim 21,
Recovering the copper indium selenide nanoparticles, comprising the step of precipitating the nanoparticles by adding alcohol or acetone, method of producing copper indium selenide nanoparticles.
The method of claim 22,
Recovering the copper indium selenide nanoparticles may further include dissolving the unreacted selenium precursor by precipitating the nanoparticles and then adding tri (C _3-20 -alkyl) phosphine or triphenylphosphine. That is, the manufacturing method of the indium selenide indium nanoparticles.
24. The method of claim 23,
Recovering the copper indium selenide nanoparticles, further comprising separating the precipitated nanoparticles by centrifugation, the method for producing copper indium selenide nanoparticles.
The method of claim 1,
The size or composition, or the size and composition of the copper indium selenide nanoparticles formed can be adjusted, the manufacturing method of the copper indium selenide nanoparticles.
The method of claim 25,
Method for producing a copper indium selenide nanoparticles, the size of the copper indium selenide nanoparticles 2 nm to 100 nm.
Indium selenide nanoparticles prepared by the method of any one of claims 1 to 26.
The method of claim 27,
Copper indium selenide nanoparticles having a uniform size.
The method of claim 27,
The copper indium selenide nanoparticles have a size ranging from 2 nm to 100 nm.
The method of claim 27,
Copper indium selenide nanoparticles having a quantum-confinement regime.
The method of claim 27,
Copper indium selenide nanoparticles having a chalcopyrite crystal form having a regular attack point ( vacancy ).
The method of claim 31, wherein
_{CuIn 2 .5 Se 4, CuIn 1} .1 Se 2 or phosphorus, copper indium selenide nanoparticles, to obtain a crystalline form, including combinations thereof.
The method of claim 31, wherein
The lattice distortion caused by the attack point (tetragonal distortion = c / 2a, wherein a and c are lattice constants of the copper indium selenide crystal) is 0.97 to 1.06, copper indium selenide nanoparticles.

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