KR102324378B1 - Semiconductor nanoparticle with hydrophobic side chain ligand-polymer nanocomposite, preparation method thereof and optoelectronic device comprising the same - Google Patents

Abstract

The present invention relates to a semiconductor nanoparticle-polymer nanocomposite having a hydrophobic side chain ligand, a method for preparing the same, and an optoelectronic device comprising the same, and more particularly, encapsulating the surface of a semiconductor nanoparticle to which a hydrophobic side chain ligand is bound with an amphiphilic polymer. And, by using the amphiphilic polymer on the surface of the semiconductor nanoparticles as a crosslinking agent to crosslink the matrix polymer, even when the semiconductor nanoparticles are contained in a high concentration, the aggregation phenomenon between the semiconductor nanoparticles can be suppressed, and the amphipathic polymer is directly formed into the matrix. Since it acts as a crosslinking agent for the polymer, a semiconductor nanoparticle-polymer nanocomposite having high transparency and high luminescence can be prepared without additional methods such as ultraviolet or thermal curing.

Description

Semiconductor nanoparticle with hydrophobic side chain ligand-polymer nanocomposite, preparation method thereof and optoelectronic device comprising the same

The present invention relates to a semiconductor nanoparticle-polymer nanocomposite having a hydrophobic side chain ligand, a method for preparing the same, and an optoelectronic device comprising the same, and more particularly, encapsulating the surface of a semiconductor nanoparticle to which a hydrophobic side chain ligand is bound with an amphiphilic polymer. And, by using the amphiphilic polymer on the surface of the semiconductor nanoparticles as a crosslinking agent to crosslink the matrix polymer, even when the semiconductor nanoparticles are contained in a high concentration, the aggregation phenomenon between the semiconductor nanoparticles can be suppressed, and the amphipathic polymer is directly formed into the matrix. It relates to a technology capable of producing a semiconductor nanoparticle-polymer nanocomposite with high transparency and high luminescence without additional methods such as ultraviolet or thermal curing because it acts as a crosslinking agent for a polymer.

Fluorescent semiconductor nanocrystals or quantum dots (QDs) have attracted great interest in the development of next-generation devices such as light emitting diodes, solar cells, and light emitting solar concentrators due to their excellent optical properties (Non-Patent Document 1).

In particular, due to the high color purity of quantum dots, photoluminescence quantum yield (PLQY), and photochemical stability, it is suitable as an alternative phosphor for light emitting diodes (LEDs). For example, in a white LED application, quantum dots are used as a color converter that converts blue light of an LED chip into green and red to generate white light (Non-Patent Document 2).

In these applications, quantum dots are used in the form of polymer nanocomposites composed of quantum dots embedded in a polymer matrix that protects them from harsh environments. Among the various types of polymers used for LED applications, silicone-based polymers are widely used because of their excellent visible light transmittance, thermal stability, and light extraction efficiency. However, when a silicon-based polymer is used as a matrix, it is difficult to prepare a nanocomposite having high transparency and high luminescence due to aggregation of quantum dots and high curing temperature (Non-Patent Document 3).

The aggregation of quantum dots in a polymer matrix is usually accompanied by severe degradation of optical properties due to light scattering by quantum dot aggregates and luminescence quenching by Forster resonance energy transfer (FRET) between adjacent quantum dots. In addition, the high curing temperature of the silicone polymer can damage the surface of the quantum dots by separating the surface ligands and creating a trap state to reduce the quantum efficiency (QY; quantum yield) of each quantum dot (Non-Patent Documents 4 and 5).

Various studies have been conducted to improve the dispersibility of quantum dots in a silicon matrix, for example, replacing the surface ligands of quantum dots with ligands that are more compatible with the silicon matrix. In our previous work, the dispersion of quantum dots in a poly(dimethylsiloxane) (PDMS) matrix was improved by modifying the surface of the quantum dots with a hydrophobic ligand containing a thiol binding group, but the quantum efficiency (QE) of the nanocomposite was not significant. did not improve significantly. Tao et al. made transparent QD/PDMS nanocomposites using bimodal PDMS-grafted quantum dots (QDs), but the quantum dot concentration in the nanocomposites was low (less than 1 wt %) and PDMS-grafted QDs after ligand exchange. The quantum efficiencies of were significantly decreased (~ 50%). Both methods used a ligand exchange reaction that adversely affects the surface passivation of quantum dots and reduces quantum efficiency (Non-Patent Documents 6 and 7).

Therefore, the present inventors encapsulate the surface of the semiconductor nanoparticles to which the hydrophobic side chain ligand is bound with an amphiphilic polymer, and use the amphiphilic polymer on the surface of the semiconductor nanoparticles as a crosslinking agent to crosslink the matrix polymer, thereby increasing the semiconductor nanoparticles to a high concentration. Even when contained, aggregation between semiconductor nanoparticles can be suppressed, and since the amphiphilic polymer directly acts as a crosslinking agent for the matrix polymer, high transparency and high luminescence semiconductor nanoparticle-polymer nanocomposite without additional methods such as UV or thermal curing The present invention was completed by focusing on that it can be manufactured.

Non-Patent Literature 1. Nozik, A. J. Physica E: Low-dimensional Systems and Nanostructures 14.1-2 (2002): 115-120. Non-Patent Document 2. Jang, Ho Seong, et al. Advanced Materials 20.14 (2008): 2696-2702. Non-Patent Document 3. Ziegler, Jan, et al. Advanced materials 20.21 (2008): 4068-4073. Non-Patent Document 4. Lunz, Manuela, et al. Superlattices and Microstructures 47.1 (2010): 98-102. Non-Patent Document 5. Li, Yangyang, and Ben Q. Li. RSC Advances 4.47 (2014): 24612-24618. Non-Patent Document 6. Yoon, Cheolsang, et al. Colloids and Surfaces A: Physicochemical and Engineering Aspects 428 (2013): 86-91. Non-Patent Document 7. Tao, Peng, et al. Journal of Materials Chemistry C 1.1 (2013): 86-94.

The present invention has been devised in consideration of the above problems, and an object of the present invention is to encapsulate the surface of semiconductor nanoparticles to which a hydrophobic side chain ligand is bound with an amphiphilic polymer, and to use the amphiphilic polymer on the surface of the semiconductor nanoparticles as a crosslinking agent. By crosslinking the matrix polymer using It is an object to prepare a semiconductor nanoparticle-polymer nanocomposite with high transparency and high luminescence without the need for it.

One aspect of the present invention for achieving the object as described above contains (i) a polymer matrix and (ii) a plurality of semiconductor nanoparticles dispersed and embedded in the polymer matrix, the plurality of semiconductor nanoparticles are each encapsulated by an amphiphilic polymer, and the semiconductor nanoparticles have a core-shell multilayer structure, and contain a hydrophobic side chain ligand of _{C 1} -C _{100 alkyl bound to the outermost shell, and the semiconductor} Semiconductor nanoparticles having a hydrophobic side chain ligand, characterized in that the semiconductor nanoparticles are encapsulated by a hydrophobic interaction between a hydrophobic side chain ligand bound to the nanoparticles and a hydrophobic group of the amphipathic polymer - a polymer nanocomposite is about

Another aspect of the present invention relates to a film comprising a semiconductor nanoparticle-polymer nanocomposite having a hydrophobic side chain ligand according to the present invention.

Another aspect of the present invention relates to a light emitting diode comprising a semiconductor nanoparticle-polymer nanocomposite having a hydrophobic side chain ligand according to the present invention.

Another aspect of the present invention relates to an optoelectronic device comprising a semiconductor nanoparticle-polymer nanocomposite having a hydrophobic side chain ligand according to the present invention.

Another aspect of the present invention is (a) dissolving an amphiphilic polymer in a suspension in which the semiconductor nanoparticles are dispersed to form semiconductor nanoparticles encapsulated by the amphiphilic polymer, and (b) in the amphiphilic polymer It was added to the matrix polymer in the suspension containing the semiconductor nanoparticles encapsulated by the method comprising: mixing at room temperature, and the semiconductor nanoparticles have a core-a has a multilayer structure of a shell-type, coupled to the outermost shell, C ₁ -C ₁₀₀ containing a hydrophobic side chain ligand of alkyl, characterized in that the semiconductor nanoparticles are encapsulated by a hydrophobic interaction between the hydrophobic side chain ligand bound to the semiconductor nanoparticles and the hydrophobic group of the amphiphilic polymer which relates to a method for preparing a semiconductor nanoparticle-polymer nanocomposite having a hydrophobic side chain ligand.

According to the present invention, by encapsulating the surface of the semiconductor nanoparticles to which the hydrophobic side chain ligand is bound with an amphiphilic polymer, and using the amphiphilic polymer on the surface of the semiconductor nanoparticles as a crosslinking agent to crosslink the polymer matrix, Even when contained, aggregation between semiconductor nanoparticles can be suppressed, and since the amphiphilic polymer directly acts as a crosslinking agent for the matrix polymer, high transparency and high luminescence semiconductor nanoparticle-polymer nanocomposite without additional methods such as UV or thermal curing can be manufactured.

1 is a graph showing (a) PL intensity of CdSe@ZnS/ZnS quantum dots (QD) synthesized from Preparation Example 1 of the present invention and QD-PSMA formed from Example 1, (b) TEM image, (c) PGMEA Images and (d, e) quasi-elastic light scattering (QELS) result graphs showing colloidal stability in (1-Methoxy-2-Propyl Acetate) [(d) QD of Preparation Example 1, (e) Example 1 QD-PSMA].
Figure 2 is a schematic diagram showing the gelation (gelation) between the surface-modified QD (QD-PSMA) and amine-terminated PDMS in the process of preparing the QD-PSMA / PDMS nanocomposite from Example 1 of the present invention.
3 is an image showing the gelation reaction results according _{to the maleic anhydride (MA)/NH 2} ratio in the process of preparing the QD-PSMA/PDMS nanocomposite from Example 1 of the present invention.
4 is an image of QD-PSMA/PDMA nanocomposite on a glass substrate according to QD concentration when _{maleic anhydride (MA)/NH 2} ratio is 2.2 according to Example 1 of the present invention.
5 is a graph showing (a) photoluminescence spectrum and (b) transmittance of the QD-PSMA/PDMA nanocomposite film prepared from Example 1 of the present invention and the QD/sylgard nanocomposite prepared from Comparative Example [QD- The figures next to PSMA/PDMA and QD/sylgard indicate the concentration of QD in weight percent].
6 is a confocal microscope image of (a) QD-PSMA/PDMS prepared from Example 1 and (b) QD/sylgard nanocomposite prepared from Comparative Example of the present invention, (c, d) Example 1 Transmission electron microscopy (TEM) images of QD-PSMA/PDMS complexes at different QD concentrations (1 wt%, 10 wt).
7 shows (a) the luminous efficiency and ( b) Emission (EL) spectrum of the LED chip using 1 wt% QD-PSMA/PDMS and 1 wt% QD/Sylgard.

Hereinafter, various aspects and various embodiments of the present invention will be described in more detail.

In the case of manufacturing a semiconductor nanoparticle-polymer composite using a conventional silicon-based polymer matrix, it is difficult to prepare a semiconductor nanoparticle-polymer composite having high transparency and high luminescence due to aggregation of semiconductor nanoparticles and a high curing temperature of silicon. did. In the present invention, the surface of the semiconductor nanoparticles to which the hydrophobic side chain ligand is bound is encapsulated with an amphipathic polymer, and the matrix polymer is crosslinked by using the amphiphilic polymer on the surface of the semiconductor nanoparticles as a crosslinking agent, thereby containing semiconductor nanoparticles at a high concentration. In this case, aggregation between semiconductor nanoparticles can be suppressed, and the amphiphilic polymer directly acts as a crosslinking agent for the matrix polymer, so a semiconductor nanoparticle-polymer nanocomposite with high transparency and high luminescence can be prepared without additional methods such as UV or thermal curing. It was possible to complete the present invention by focusing on that.

One aspect of the present invention contains (i) a polymer matrix and (ii) a plurality of semiconductor nanoparticles dispersed and embedded in the polymer matrix, wherein the plurality of semiconductor nanoparticles are each encapsulated by an amphiphilic polymer and the semiconductor nanoparticles have a core-shell type multilayer structure, and C ₁ -C ₁₀₀ alkyl, more specifically C ₅ -C ₅₀ alkyl, more specifically C ₁₅ - It _{contains a hydrophobic side chain ligand of C 20} alkyl, wherein the semiconductor nanoparticles are encapsulated by a hydrophobic interaction between a hydrophobic side chain ligand bound to the semiconductor nanoparticles and a hydrophobic group of the amphiphilic polymer , to a semiconductor nanoparticle-polymer nanocomposite having a hydrophobic side chain ligand.

As a specific example, the semiconductor nanoparticles have a metal (M) present in the outermost shell and a carboxyl group (-COOH) of oleic acid (OA), a solvent used for synthesis, in the form of M-OOC-C ₁₇ , C _A hydrophobic side chain ligand that is an 18 alkyl may be attached (see FIG. 2).

According to one embodiment, the polymer matrix may be an amine-terminated silicone-based polymer, and the silicone-based polymer is, for example, polydimethylsiloxane (PDMS), polymethylsiloxane, partially alkylated polymethylsiloxane, polyalkylmethylsiloxane. , but may be any one selected from polyphenylmethylsiloxane and combinations thereof, but is not limited thereto. Specifically, PDMS may be used.

According to another embodiment, the polymer matrix may be an amine-terminated PDMS represented by Formula 1 below.

[Formula 1]

Said n is an integer of 30-700.

The weight average molecular weight of the amine-terminated PDMS may be 2,000 to 53,000, specifically 20,000 to 40,000, and more specifically 25,000 to 30,000. When the weight average molecular weight is less than 2,000, the semiconductor nanoparticles are formed by the PDMS matrix. It may not be embedded and a problem may occur, and when it exceeds 53,000, the viscosity of the polymer is higher than necessary, so that the semiconductor nanoparticles may not be uniformly dispersed in the polymer matrix.

According to another embodiment, the type of the semiconductor nanoparticles is not particularly limited, and known or commercially available semiconductor nanoparticles may be used. For example, the semiconductor nanoparticles may include a group II-VI compound, a group III-V compound, a group IV-VI compound, a group IV compound, a group I-III-VI compound, a group I-group-II-group-IV- It may include any one selected from Group VI compounds and combinations thereof.

The group II-VI compound is a binary compound selected from the group consisting of CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS, and mixtures thereof; CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgZnTe, HgZnS, HgZnSe, HgZnTe, MgZnS, MgZnTe, MgZnS and mixtures thereof bovine compounds; and HgZnTeS, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe, and mixtures thereof. The group II-VI compound may further include a group III metal.

The group III-V compound is a binary compound selected from the group consisting of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, and mixtures thereof; a ternary compound selected from the group consisting of GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, and mixtures thereof; and GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb, and mixtures thereof. have. The group III-V compound may further include a group II metal (e.g., InZnP).

The group IV-VI compound is a binary compound selected from the group consisting of SnS, SnSe, SnTe, PbS, PbSe, PbTe, and mixtures thereof; a ternary compound selected from the group consisting of SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, and mixtures thereof; and a quaternary compound selected from the group consisting of SnPbSSe, SnPbSeTe, SnPbSTe, and mixtures thereof. Examples of the group I-III-VI compound include, but are not limited to _{, CuInSe 2} , CuInS _{2 , CuInGaSe, and CuInGaS.} Examples of the group I-II-IV-VI compound include, but are not limited to, CuZnSnSe and CuZnSnS.

The group IV element or compound is a single element selected from the group consisting of Si, Ge, and mixtures thereof; and SiC, SiGe, and mixtures thereof.

The binary, ternary, or quaternary compound may be present in the particle at a uniform concentration, or may be present in the same particle as the concentration distribution is partially divided into different states. One semiconductor nanoparticle may have a core/shell structure surrounding another semiconductor nanoparticle. The interface between the core and the shell may have a concentration gradient in which the concentration of the element present in the shell decreases toward the center. In addition, the semiconductor nanocrystal may have a structure including one semiconductor nanocrystal core and a multi-layered shell surrounding the semiconductor nanocrystal core. In this case, the multi-layered shell structure has a shell structure of two or more layers, and each layer may have a single composition or an alloy or a concentration gradient.

Specifically, the semiconductor nanoparticles may be quantum dots of CdSe/ZnS/ZnS (core/shell/shell) or InP/GaP/ZnS (core/shell/shell), and more specifically, the semiconductor nanoparticles are (1) a CdSe-core portion, (2) a ZnS-first shell portion surrounding the core portion, and (3) a ZnS-second shell portion surrounding the first shell portion, wherein the ZnS-first shell portion comprises the CdSe - A concentration gradient may be gradually formed from the core portion to form an alloy with the CdSe-core portion. Hereinafter, the semiconductor nanoparticles will be described as CdSe@ZnS/ZnS.

According to another embodiment, the amphiphilic polymer may include a maleic anhydride monomer. When the polymer matrix is an amine-terminated PDMS and the amphiphilic polymer includes a maleic anhydride monomer, a crosslinking reaction between the maleic anhydride group included in the amphiphilic polymer and the amine group of the amine-terminated PDMS At the same time as forming an amine-terminated PDMS matrix through gelation, the semiconductor nanoparticles having a hydrophobic side chain in an embedded form in which the plurality of semiconductor nanoparticles are dispersed on the amine-terminated PDMS matrix to form a polymer nanocomposite can

According to another embodiment, the amphiphilic polymer may be a cumene-terminated poly(styrene-co-maleic anhydride) represented by the following Chemical Formula 2.

[Formula 2]

Wherein m is an integer of 7 to 21.

Said n is an integer of 1-6.

According to another embodiment, the diameter of the semiconductor nanoparticles encapsulated by the amphiphilic polymer may be 1 to 100 nm, specifically 15 to 50 nm, more specifically 22 to 25 nm. If the diameter of the semiconductor nanoparticles encapsulated by the amphiphilic polymer is out of the range of 1 to 100 nm, the semiconductor nanoparticles may not be embedded by the polymer matrix and a problem may occur.

According to another embodiment, the concentration of the semiconductor nanoparticles is 0.01 to 80% by weight, specifically 0.05 to 30% by weight, more specifically, based on the total weight of the semiconductor nanoparticles-polymer nanocomposite having the hydrophobic side chain ligand. 0.1 to 15% by weight, more specifically 0.8 to 3% by weight. Even when the semiconductor nanoparticles are included in a high concentration as described above, the amphiphilic polymer layer surrounding the surface of the semiconductor nanoparticles has an effect of having uniform dispersibility without aggregation of the semiconductor nanoparticles with each other, and specifically, When the concentration of the semiconductor nanoparticles was 0.8 to 3 wt%, it was confirmed that luminous efficacy was significantly improved compared to the case where the concentration was outside the above concentration range.

Another aspect of the present invention relates to a film comprising a semiconductor nanoparticle-polymer nanocomposite having a hydrophobic side chain ligand according to the present invention.

According to one embodiment, the film comprising the semiconductor nanoparticle-polymer nanocomposite having the hydrophobic side chain ligand is prepared by coating a suspension containing the semiconductor nanoparticle-polymer nanocomposite having the hydrophobic side chain ligand on a glass substrate, followed by a solvent It may be prepared by evaporating, but is not limited thereto.

Another aspect of the present invention relates to a light emitting diode comprising a semiconductor nanoparticle-polymer nanocomposite having a hydrophobic side chain ligand according to the present invention.

Another aspect of the present invention relates to an optoelectronic device comprising a semiconductor nanoparticle-polymer nanocomposite having a hydrophobic side chain ligand according to the present invention.

Another aspect of the present invention is (a) dissolving an amphiphilic polymer in a suspension in which the semiconductor nanoparticles are dispersed to form semiconductor nanoparticles encapsulated by the amphiphilic polymer, and (b) in the amphiphilic polymer It was added to the matrix polymer in the suspension containing the semiconductor nanoparticles encapsulated by the method comprising: mixing at room temperature, and the semiconductor nanoparticles have a core-a has a multilayer structure of a shell-type, coupled to the outermost shell, C ₁ -C ₁₀₀ containing a hydrophobic side chain ligand of alkyl, characterized in that the semiconductor nanoparticles are encapsulated by a hydrophobic interaction between the hydrophobic side chain ligand bound to the semiconductor nanoparticles and the hydrophobic group of the amphiphilic polymer which relates to a method for preparing a semiconductor nanoparticle-polymer nanocomposite having a hydrophobic side chain ligand.

According to one embodiment, the matrix polymer may be an amine-terminated silicone-based polymer, and the silicone-based polymer is, for example, polydimethylsiloxane (PDMS), polymethylsiloxane, partially alkylated polymethylsiloxane, polyalkylmethylsiloxane. , but may be any one selected from polyphenylmethylsiloxane and combinations thereof, but is not limited thereto. Specifically, PDMS may be used.

According to another embodiment, the matrix polymer may be an amine-terminated PDMS represented by Formula 1 below.

[Formula 1]

Said n is an integer of 30-700.

The weight average molecular weight of the amine-terminated PDMS may be 2,000 to 53,000, specifically 20,000 to 40,000, and more specifically 25,000 to 30,000. When the weight average molecular weight is less than 2,000, the semiconductor nanoparticles are formed by the PDMS matrix. If it is not surrounded and is exposed, a problem may occur, and when it exceeds 53,000, the viscosity of the polymer becomes higher than necessary, and a problem may occur that the semiconductor nanoparticles are not uniformly dispersed in the polymer matrix.

According to another embodiment, the semiconductor nanoparticles are any one of II-VI-based compound semiconductor nanoparticles, III-V-based compound semiconductor nanoparticles, IV-VI-based compound semiconductor nanoparticles, Si-based nanoparticles, and compounds thereof of nanoparticles.

According to another embodiment, the type of the semiconductor nanoparticles is not particularly limited, and known or commercially available quantum dots may be used. For example, the semiconductor nanoparticles may include a group II-VI compound, a group III-V compound, a group IV-VI compound, a group IV compound, a group I-III-VI compound, a group I-group-II-group-IV- It may include any one selected from Group VI compounds and combinations thereof.

According to another embodiment, the amphiphilic polymer may include a maleic anhydride monomer. When the polymer matrix is an amine-terminated PDMS and the amphiphilic polymer includes a maleic anhydride monomer, a crosslinking reaction between the maleic anhydride group included in the amphiphilic polymer and the amine group of the amine-terminated PDMS At the same time as forming an amine-terminated PDMS matrix through gelation, the semiconductor nanoparticles having a hydrophobic side chain in an embedded form in which the plurality of semiconductor nanoparticles are dispersed on the amine-terminated PDMS matrix to form a polymer nanocomposite can

According to another embodiment, the amphiphilic polymer may be a cumene-terminated poly(styrene-co-maleic anhydride) represented by the following Chemical Formula 2.

[Formula 2]

Wherein m is an integer of 7 to 21.

Said n is an integer of 1-6.

According to another embodiment, the concentration of the semiconductor nanoparticles is 0.1 to 15% by weight based on the total weight of the semiconductor nanoparticles-polymer nanocomposite having the hydrophobic side chain ligand, and the amphiphilic polymer comprises a maleic anhydride monomer, , The matrix polymer is an amine-terminated silicone-based polymer, and the molar ratio of maleic anhydride/amine may be 0.4 to 3.7, specifically 1 to 3, and more specifically 2 to 2.5. Specifically, when the molar ratio of maleic anhydride/amine is out of the range of 0.4 to 3.7 under the concentration conditions of the semiconductor nanoparticles (0.1 to 15% by weight), the maleic anhydride group of the amphiphilic polymer and the silicone-based polymer It was confirmed that gelation did not occur due to the crosslinking reaction of the amine group of , so that the semiconductor nanoparticle-polymer complex having a hydrophobic side chain ligand was not formed.

Hereinafter, manufacturing examples and embodiments according to the present invention will be described in detail with accompanying drawings.

<Example>

ingredient

Cadmium Acetate (Cd(OAc) ₂ , 99.99%), Indium Acetate (In(OAc) ₃ , 99.99 %), 1-Dodekenthiol (1-DDT, > 98%), Gallium Chloride (GaCl3, 99.999%) , zinc oxide (ZnO, 99.99%), zinc acetate (Zn(OAc) ₂ , 99.99%), oleic acid (OA, 90%), trioctylphosphine (TOP, 90%), 1-octadecene (1-ODE) ), propylene glycol monomethyl ether acetate (PGMEA, 99.5%), cumene-terminated poly(styrene-co-maleic anhydride) (PSMA, Mn: ~1,900 (GPC)), bis(3-aminopropyl) terminated poly( Dimethylsiloxane) (H ₂ N-PDMS-NH ₂ , Mn: ˜27,000) was purchased from Aldrich. Selenium (99.999%, powder) and sulfur (99.5%, powder) were purchased from Alfa Aesar. Tris(trimethicsilyl)phosphine (TMS ₃ P, 95%) was purchased from JSI Silicone. Ethyl alcohol (99.99%), ethanol (99.99%), acetone (99.99%), n-hexane (95.0%), and chloroform (99.99%) were purchased from Duksan Chemical. All chemicals were used without further purification.

Preparation Example 1: Synthesis of CdSe@ZnS/ZnS quantum dots

CdSe@ZnS/ZnS core/shell quantum dots with high luminescence and stable green-emitting were synthesized by the previously reported method (Lee, Ki-Heon, et al. ACS nano 8.5 (2014): 4893-4901).

In a 50 mL three-necked flask, _{0.14 mmol of Cd(OAc) 2} , 3.41 mmol of Zn(OAc) ₂ and 7 mL of OA were added and degassed at 150° C. under vacuum until the vacuum reached 100 mTorr. Then, the temperature was lowered to 100° C. and 15 mL of 1-ODE was injected into the flask, followed by degassing for 30 minutes. After degassing, the temperature was raised to 310° C. to obtain a clear solution of _{Cd(OA) 2} and Zn(OA) _{2 while maintaining the Ar purge.}

Following this step, 2 mL TOPSeS prepared by dissolving 5 mmol Se and 5 mmol S in 5 mL of TOP was rapidly injected into the flask at 310° C. and reacted for 10 minutes for growth of CdSe@ZnS alloy core. . To increase the stability, a 2.4 mL S source (3.2 mmol S in 4.8 mL 1-ODE) was injected into the suspension of the CdSe@ZnS core, and the CdSe@ZnS core was coated with a ZnS shell. After 12 min, 5 mL Zn source ( _{4.92 mmol of Zn(OAc) 2} in 2 mL OA and 4 mL ODE) was injected into the suspension. Then, 5 mL S precursor (19.3 mmol S in 10 mL TOP) was added dropwise to the reaction medium at a rate of 0.5 mL/min, and reacted for 20 minutes. To complete the reaction, the reactor was rapidly cooled to room temperature. The synthesized quantum dots (QDs) were centrifuged at 9000 rpm for 10 minutes at 9000 rpm by adding 4 mL of hexane and 50 mL of acetone, redispersed in chloroform to precipitate, and the purification step was repeated 3 times, and the quantum dots were then Disperse in chloroform for use. The thus synthesized CdSe @ ZnS / ZnS quantum dot is a carboxyl group (-COOH) of the oleic acid (OA) used in the synthesis and Zn present in its outermost shell is combined with Zn-OOC-C ₁₇ type, the C ₁₈ alkyl It was confirmed that the hydrophobic side chain ligand was attached (see FIG. 2).

Preparation Example 2: Synthesis of InP/GaP/ZnS quantum dots

High luminescence and stable green-emitting InP/GaP/ZnS core/shell/shell quantum dots were synthesized by the previously reported method (Park, Joong Pill, et al. Sci. Rep. 6 (2016): 2-7). .

In a 50 mL three-necked flask, add _{0.24 mmol of In(OAc) 3} , 1 mmol of Zn(OAc) ₂ , 2.17 mmol of myristic acid and 4 mL of 1-ODE, and vacuum at 110 °C until the vacuum reaches 100 mTorr. was degassed for 2 hours. Then, while the temperature was lowered to 25 °C and the Ar purge was maintained, _{two types of a mixture of (TMS 3} )P 0.19 mmol and 1-ODE 1 ml and GaCl ₃ 0.085 mmol and 1-ODE 1 ml were injected into the flask. Then, the temperature of the mixture was raised to 300 °C within 10 minutes, and when the temperature reached 300 °C, 1 mmol of 1-DDT was injected and the reaction was carried out for 10 minutes. For additional shell growth, 2 mmol of zinc oleate was injected, and 3 mmol of 1-DDT was injected, and the reaction was carried out for 10 minutes. The synthesized quantum dots (QDs) were centrifuged at 9000 rpm for 10 minutes by adding 4 mL of hexane and 50 mL of ethanol, redispersed in chloroform to precipitate, and then the purification step was repeated 3 times, and the quantum dots were then Disperse in chloroform for use.

Example 1: Surface modification by amphiphilic polymer and preparation of QD-PSMA/PDMS nanocomposite (1)

Surface modification of the CdSe@ZnS/ZnS quantum dots (QD) of Preparation Example 1 using an amphiphilic polymer (PSMA) is a hydrophobic interaction between a hydrophobic side chain ligand bound to the surface of the quantum dot and a hydrophobic group of PSMA (amphiphilic polymer) action was used. Different amounts of PSMA were added to the quantum dot suspension in 2 mL chloroform. The QD/PSMA suspension was stirred for 6 h to dissolve PSMA to form PSMA-modified QDs (QD-PSMA).

Then, to prepare QD-PSMA/PDMS nanocomposites, amine-terminated _{-PDMS (H 2} N-PDMS-NH ₂ ) was mixed with the QD-PSMA suspension at room temperature to cross-link the amphiphilic polymer on QDs and PDMS By enabling the QD-PSMA / PDMS nanocomposite was prepared.

Example 2: Surface modification by amphiphilic polymer and preparation of QD-PSMA/PDMS nanocomposite (2)

A QD-PSMA/PDMS nanocomposite was prepared in the same manner as in Example 1, except that the InP/GaP/ZnS quantum dots (QDs) prepared in Preparation Example 2 were used instead of the quantum dots prepared in Preparation Example 1.

Comparative Example: Preparation of unmodified QD/PDMS nanocomposites

Nanocomposites were prepared using unmodified quantum dots (QDs) and a commercially available PDMS polymer (Sylgard-184, Dow Corning). Specifically, the CdSe@ZnS/ZnS quantum dots (QD) synthesized in Preparation Example 1 were mixed with 1 g of Sylgard polymer and 0.1 g of a curing agent. The mixture was vacuum dried at room temperature for 1 hour to remove solvent and air bubbles, and cured in a convection oven at 150° C. for 2 hours to obtain QD/Sylgard nanocomposites.

<Experimental example>

Experimental Example 1: LED Application

For the LED experiment, the QD-PSMA/PDMS composite prepared in Example 1 was placed on a blue LED chip (large light illumination, λex = 450 nm) surface mount device (SMD) and cured at 150°C. For comparison, a blue LED was prepared using the QD/Sylgard nanocomposite prepared in Comparative Example. Then, the luminescence characteristics of the LED were measured using an integrating sphere equipped with an LED test device.

Experimental Example 2: Characterization

The size and shape of the quantum dots synthesized from Preparation Examples were determined using a transmission electron microscope (TEM, JEM-2100, JEOL) and quasi-elastic light scattering (QELS, Nano-ZS, Malvern). The UV-Vis absorption spectrum of the quantum dots and the transmittance of the nanocomposite film were confirmed using a spectrophotometer (V-730, JASCO). Emission spectra were acquired using a Perkin-Elmer LS-55 photoluminescence (PL) spectrometer. The dispersion state of the QD-PSMA/PDMS of Example 1 and the QD/Sylgard nanocomposite of Comparative Example was observed with a confocal microscope (LSM-880, ZEISS). In order to estimate the light emission and color conversion efficiency of the LED, an integrating sphere with a 460 nm Xe laser was used as an excitation energy source (QE-1000, Otsuka Electronics).

<Experiment result>

1. Characterization of Synthetic and Surface Modified QDs

High luminescence green-emitting CdSe@ZnS/ZnS quantum dots capped with OA and TOP were synthesized by the previously reported method as described above, and QD-PSMA was produced by surface modification with PSMA.

Referring to FIG. 1(a), the PL spectrum _{confirms that the PL intensity and λ max} of QD-PSMA were maintained almost constant even after surface modification. It is reported that the PL intensity of quantum dots generally decreases after ligand exchange due to segregation of the native surface ligand. However, by coating the amphiphilic polymer on the surface of the quantum dot, the native ligand was maintained on the surface to preserve the PL intensity and λ _max .

Also, after surface modification, the average hydrodynamic diameter of QDs obtained from QELS increased slightly from 18.5 nm to 23.26 nm (Fig. 1(d) and 1(e)), whereas TEM showed no noticeable size change (Fig. 1). (b)). This discrepancy between QELS and TEM sizes suggests that the increase in hydrodynamic diameter may be due to encapsulation by PSMA.

In addition, referring to FIG. 1(c), when a polar solvent such as PGMEA (1-Methoxy-2-Propyl Acetate) was added to the synthesized QD suspension, aggregation of QDs occurred due to the hydrophobicity of the QD surface. However, the PSMA surface-modified (-capped) QDs were stably maintained in a colloidal shape in the PGMEA solution, confirming that the surface modification with PSMA was successfully performed.

2. Formation of QD-PSMA/PDMS Nanocomposites and Preparation of Films

The QD-PSMA/PDMS nanocomposite prepared in Example 1 was prepared by mixing QD-PSMA and an amine-terminated PDMS polymer. The mixture gelled within 2 hours, which may be caused by a crosslinking reaction between maleic anhydride (MA) groups on the QD surface and amine groups in PDMS. Referring to FIG. 2 , it can be confirmed that QD-PSMA acts as a crosslinking agent for the PDMS polymer.

To understand the effect of the amount of PSMA on the crosslinking reaction, _{the molar ratio of MA on QD-PSMA to NH 2} of PDMS was varied from 0.1 to 14.8, and the QD concentration was kept constant at 1 wt%. 3 shows that gelation did not occur when the MA/NH ₂ ratio was lower than 0.4 or greater than 3.7, indicating the optimal amount of PSMA for gelation. It was confirmed that if the MA/NH ₂ ratio was too low or too high, the degree of crosslinking reaction in the PDMS network was not high enough to cause gelation, resulting in a flowable mixture. From the above results, _{the molar ratio of MA/NH 2} was set to 2.2, and after coating a mixture of QD-PSMA and PDMS on a glass substrate, the solvent was evaporated to prepare a QD-PSMA/PDMS nanocomposite film. For comparison, the nanocomposite (QD/Sylgard) in the same manner as the QD-PSMA/PDMS nanocomposite film using the nanocomposite (QD/Sylgard) of Comparative Example 1 prepared using unmodified QD and a commercial polymer A film was prepared.

3. Optical properties of QD-PSMA/PDMS nanocomposites

The optical properties of the QD-PSMA/PDMS nanocomposite film and the QD/Sylgard nanocomposite film were compared. 4, it was confirmed that a transparent QD-PSMA/PDMS film could be obtained in a wide range of QD concentrations (0.1 to 30 wt %), whereas the QD/Sylgard nanocomposite film was translucent even at a QD concentration of 1 wt %. was confirmed. In general, the decrease in transparency of nanoparticle-based nanocomposites is due to aggregation phenomena known to cause _{light scattering and a redshift of λ max in the emission spectrum.} The QD-PSMA/PDMS film maintained transparency even when the QD concentration was very high (30 wt %), and only a slight redshift was observed as the QD concentration increased (Fig. 5(a)). On the other hand, the QD/Sylgard nanocomposite film was translucent due to light scattering, and a red shift was evident even at a concentration of 1 wt%. These results suggest that QDs were distributed in the form of aggregates in the QD/Sylgard nanocomposite film.

In addition, the transmittance of QD-PSMA/PDMS nanocomposite films was compared by UV-Vis spectroscopy. Several factors can affect transmittance in particle-embedded nanocomposites. According to the Rayleigh scattering theory, the transparency loss of the nanocomposite is a result of light scattering by spherical nanoparticles with radius r and volume fraction φ _{p as follows:}

[Equation 1]

where T is the transmittance of the nanocomposite, λ is the wavelength of light, x is the optical path length, and n _p and n _m are the refractive indices of the nanoparticles and the polymer matrix, respectively. Here, all parameters are identical except for the particle size within the film. In general, the particle size should be less than about one tenth of the wavelength of light to minimize loss of transparency due to light scattering. Therefore, aggregation of QDs can lead to significant light scattering and thus reduce the transparency of the nanocomposite film. Figure 5(b) shows that the QD-PSMA/PDMS film exhibited much higher transmittance than the QD/Sylgard film at all wavelengths regardless of the QD concentration. This may be because the aggregation of the QDs in the QD/Sylgard film resulted in significant light scattering and transmittance reduction. In addition, the increase in QD concentration decreased the transmittance of the QD-PSMA/PDMS film. Since the light scattering is negligible in the QD-PSMA/PDMS film (Fig. 4), the transmittance depends mainly on absorption by the QDs, so the transmittance with QD concentration may decrease.

4. Dispersion State in Nanocomposite Film

In order to confirm the relationship between the optical properties of the nanocomposite film and the dispersion state, the dispersion state of QDs in QD-PSMA/PDMS and QD/Sylgard films was directly observed using confocal microscopy and focused ion beam (FIB) TEM. . 6(a) and 6(b) show that the distribution of QDs is uniform in QD-PSMA/PDMS, whereas in QD/Sylgard, there are mainly micro-sized fluorescent particles and pores (non-fluorescence part) due to significant aggregation in QD/Sylgard. show that there is In addition, FIB samples of QD-PSMA/PDMS were prepared for TEM analysis, which shows that QDs exist as isolated nanoparticles without aggregation even at high concentrations ( FIGS. 6(c) and 6(d)).

The discrepancy in the dispersion state of QDs can be explained as follows. In the QD/Sylgard nanocomposite, van der Waals attraction between the QDs was dominant, causing severe aggregation of the QDs in the polymer matrix, whereas in the QD-PSMA/PDMS nanocomposite the QDs were sterilized by the PSMA polymer encapsulation layer providing steric stabilization. The separation reduces the van der Waals attraction between the QDs. In addition, the QDs were surrounded by the PDMS network due to the crosslinking reaction between QD-PSMA and amine-terminated PDMS. The amine-terminated PDMS in this study had a molecular weight of 27,000, which was high enough to act as a spacer to prevent aggregation of QDs.

5. LED application of QD-PSMA/PDMS nanocomposite

LED chips were prepared by curing QD 1 wt% QD/Sylgard nanocomposites and QD-PSMA/PDMS nanocomposites of various QD concentrations (0.1, 0.5, 1, 5, 10, 15 wt %) on a blue LED SMD chip. The poor dispersion of QDs in QD/Sylgard prevented the fabrication of LED chips at high concentrations, while LED chips could be fabricated using QD-PSMA/PDMS even at high concentrations. In the present invention, the luminous efficiency of the LED chip was compared using an integrating sphere (with LED). When the LED was operated at 60 mA, the luminous efficiency of QD-PSMA/PDMS was higher than that of the 1 wt% QD/Sylgard nanocomposite even at a much higher QD concentration (15 wt%, Fig. 7(a)). The luminous efficiency of the QD-PSMA/PDMS nanocomposite was highest at 1 wt%.

In addition, electroluminescence spectra of LED chips using QD-PSMA/PDMS and QD/Sylgard nanocomposites were obtained at the same QD concentration (1 wt %). Fig. 7(b) shows that the LED with QD-PSMA/PDMS showed a higher luminescence intensity than QD/Sylgard even though much more blue light remained, which indicates that the QD-PSMA/PDMS nanocomposite more efficiently emits blue light. It means to get higher luminous efficiency. Conversely, QD/Sylgard LEDs exhibited not only lower emission intensity but also _{a significant redshift at λ max} (~8 nm). This result can be explained by the aggregation of QDs in QD/Sylgard nanocomposites, which blocks light propagation and causes backscattering and re-absorption, leading to a decrease in luminous efficiency and a redshift of _{λ max .} It was confirmed that the calculated color conversion efficiency (17.1%) of the LED using QD-PSMA/PDMS was much higher than that of QD/Sylgard (5.1%).

Therefore, according to the present invention, by encapsulating the surface of the semiconductor nanoparticles to which the hydrophobic side chain ligand is bound with an amphiphilic polymer, and using the amphiphilic polymer on the surface of the semiconductor nanoparticles as a crosslinking agent to crosslink the matrix polymer, the semiconductor nanoparticles are highly concentrated It is possible to suppress the aggregation phenomenon between semiconductor nanoparticles even when it contains Composites can be prepared.

Claims (13)

(i) a polymer matrix and
(ii) containing a plurality of semiconductor nanoparticles dispersed and embedded in the polymer matrix, wherein the plurality of semiconductor nanoparticles are each encapsulated by an amphiphilic polymer,
The semiconductor nanoparticles are quantum dots having a core/shell/shell structure of CdSe/ZnS/ZnS or InP/GaP/ZnS, and a hydrophobic side chain ligand of C18 alkyl is bonded to the outermost shell of the quantum dot,
The semiconductor nanoparticles are encapsulated by a hydrophobic interaction between a hydrophobic side chain ligand bound to the semiconductor nanoparticles and a hydrophobic group of the amphiphilic polymer,
The polymer matrix is an amine-terminated PDMS represented by the following formula (1),
The amphipathic polymer is a semiconductor nanoparticle-polymer nanocomposite having a hydrophobic side chain ligand, characterized in that the amphipathic polymer is a cumene-terminated poly(styrene-co-maleic anhydride) represented by the following Chemical Formula 2:
[Formula 1]

[Formula 2]

In Formula 1, n is an integer of 30 to 700,
In Formula 2, m is an integer of 7 to 21, and n is an integer of 1 to 6. delete delete delete delete delete According to claim 1,
A semiconductor nanoparticle-polymer nanocomposite having a hydrophobic side chain ligand, characterized in that the diameter of the semiconductor nanoparticles encapsulated by the amphiphilic polymer is 10 to 50 nm. According to claim 1,
The concentration of the semiconductor nanoparticles is 0.01 to 80% by weight based on the total weight of the semiconductor nanoparticles-polymer nanocomposite having the hydrophobic side chain ligand. The film comprising the semiconductor nanoparticle-polymer nanocomposite having a hydrophobic side chain ligand according to claim 1 . The light emitting diode comprising a semiconductor nanoparticle-polymer nanocomposite having a hydrophobic side chain ligand according to claim 1 . The optoelectronic device comprising a semiconductor nanoparticle-polymer nanocomposite having a hydrophobic side chain ligand according to claim 1 . (a) dissolving an amphiphilic polymer in a suspension in which the semiconductor nanoparticles are dispersed to form semiconductor nanoparticles encapsulated by the amphiphilic polymer, and (b) semiconductor nanoparticles encapsulated by the amphiphilic polymer adding a polymer matrix to the suspension containing the mixture and mixing at room temperature,
The semiconductor nanoparticles are quantum dots having a core/shell/shell structure of CdSe/ZnS/ZnS or InP/GaP/ZnS, and a hydrophobic side chain ligand of C18 alkyl is bonded to the outermost shell of the quantum dot, and is bonded to the semiconductor nanoparticles The semiconductor nanoparticles are encapsulated by the hydrophobic interaction between the hydrophobic side chain ligand and the hydrophobic group of the amphipathic polymer,
The polymer matrix is an amine-terminated PDMS represented by the following formula (1),
The amphiphilic polymer is a cumene-terminated poly(styrene-co-maleic anhydride) represented by the following formula (2), characterized in that the semiconductor nanoparticles having a hydrophobic side chain ligand-a method of producing a polymer nanocomposite:
[Formula 1]

[Formula 2]

In Formula 1, n is an integer of 30 to 700,
In Formula 2, m is an integer of 7 to 21, and n is an integer of 1 to 6. 13. The method of claim 12,
The concentration of the semiconductor nanoparticles is 0.1 to 15% by weight based on the total weight of the semiconductor nanoparticles-polymer nanocomposite having the hydrophobic side chain ligand,
The amphiphilic polymer comprises a maleic anhydride monomer,
The matrix polymer is an amine-terminated silicone-based polymer,
The molar ratio of the maleic anhydride / amine is 0.4 to 3.7, characterized in that the semiconductor nanoparticles having a hydrophobic side chain ligand-a method for producing a polymer nanocomposite.

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