WO2014035159A1

WO2014035159A1 - White light-emitting quantum dot

Info

Publication number: WO2014035159A1
Application number: PCT/KR2013/007772
Authority: WO
Inventors: 이종호; 김근태; 안현철
Original assignee: 주식회사 동진쎄미켐
Priority date: 2012-08-29
Filing date: 2013-08-29
Publication date: 2014-03-06

Abstract

The present invention relates to a white light-emitting quantum dot. More particularly, the present invention relates to a quantum dot and to a method for manufacturing same, the quantum dot comprising a core/shell structure and a ligand attached to the surface of the shell. The ligand includes a light-emitting group. The core/shell structure and the light-emitting group of the ligand may emit light having complementary colors, thus emitting white light overall. The white light-emitting quantum dot according to the present invention may emit white light alone without using a separate filter layer. Therefore, the light-emitting device which adopts the white light-emitting quantum dot of the present invention may have a simple structure while achieving excellent color purity, high stability, and high light-emitting efficiency as compared to conventional light-emitting devices.

Description

White light emitting quantum dots

The present invention relates to a white light emitting quantum dot, and more particularly, to a white light emitting quantum dot capable of white light emission as one quantum dot alone and a method of manufacturing the same.

Quantum Dot is a nano-scale semiconductor material that exhibits a quantum confinement effect. When a quantum dot receives light from an excitation source and reaches an energy excited state, the corresponding energy bandgap is itself. To release energy. In addition, by adjusting the size of the quantum dot to adjust the band gap, the electrical and optical characteristics can be adjusted so that the light emission wavelength can be adjusted only by controlling the size of the quantum dot, and because it can exhibit characteristics such as excellent color purity and high luminous efficiency, It can be applied to various devices such as photoelectric change devices.

A quantum dot as a light emitting device that has been studied in the past has been disclosed for emitting only a wavelength of one color gamut, such as US Pat. No. 6,501,109 and WO2012 / 013272, but it was impossible to emit white light with only one quantum dot, and to realize white light. In order to provide a separate filter layer, there is a difficulty in changing the wavelength of the light emitted, and thus many quantum dots have not been reported for quantum dots emitting white light by themselves, despite many necessities.

In order to solve the above problems, the present invention is capable of providing white light by itself, and to provide a white light emitting quantum dot, a manufacturing method thereof and a light emitting device including the same that can exhibit excellent color purity, high stability and high luminous efficiency. The purpose.

The present invention to achieve the above object,

A quantum dot comprising a structure of the core / shell and a ligand attached to the surface of the shell,

The ligand comprises a light emitting group,

The light emitting group of the core / shell structure and the ligand provides a white light emitting quantum dot characterized in that the light emits white light as a whole by emitting a color complementary to each other.

Preferably the structure of the core / shell may emit light in the region of 400 to less than 500 nm or light in the region of 500 to 800 nm,

When the structure of the core / shell emits light in the region of 400 to less than 500 nm, the light emitting group emits light in the region of 500 to 800 nm and the structure of the core / shell emits light in the region of 500 to 800 nm. In this case, the light emitting group may be a quantum dot that emits white light by emitting light in an area of 400 or more and less than 500 nm.

In another aspect, the present invention provides a method for producing a white light emitting quantum dot comprising the step of adding a ligand containing a light emitting group to a solution in which the structure of the core / shell dispersed.

In another aspect, the present invention provides a light emitting device comprising the white light emitting quantum dots as a light emitting material.

In another aspect, the present invention provides a method of manufacturing a light emitting device comprising the step of forming a light emitting layer with the white light emitting quantum dots.

Since the white light emitting quantum dots according to the present invention can emit white light by itself without providing a separate filter layer, the white light emitting quantum dots have a simple structure when applied to the light emitting device and have excellent color purity, high stability and high luminous efficiency compared to the conventional light emitting device. can do.

1 shows a schematic diagram of a white light emitting quantum dot according to an embodiment of the present invention.

Figure 2 shows a schematic diagram of a white light emitting quantum dot according to another embodiment of the present invention.

3 is a schematic diagram of CdSe / ZnS synthesis used in a white light emitting quantum dot according to an embodiment of the present invention.

4 is a schematic diagram showing the synthesis of white light emitting quantum dots according to an exemplary embodiment of the present invention.

5 is an FT-IR spectra of a white light emitting quantum dot according to an embodiment of the present invention.

6 is UV absorption and PL spectra of a white light emitting quantum dot according to an embodiment of the present invention.

7 is a graph illustrating device light emission efficiency of a white light emitting quantum dot according to an exemplary embodiment of the present invention.

8 illustrates an emission spectrum of a white light emitting quantum dot according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail.

The white light emitting quantum dot of the present invention is a quantum dot including a core / shell structure and a ligand attached to the surface of the shell, wherein the ligand includes a light emitting group, and the light emitting group of the core / shell structure and the ligand is complementary to each other. A white light emitting quantum dot characterized by emitting light as a whole to emit white light. That is, one quantum dot is a white light emitting quantum dot capable of emitting white light as a whole by including a ligand including a structure of a core / shell having a complementary color relationship and a light emitting group in one quantum dot.

In the present invention, the light emission wavelength of the ligand containing the light emitting group and the structure of the core / shell having a complementary color relationship can be arbitrarily adjusted. Specifically, the structure of the core / shell emits light in the region of 400 nm to less than 500 nm, or Can emit light in the range of 500 to 800 nm

When the structure of the core / shell emits light in the region of 400 to less than 500 nm, the light emitting group emits light in the region of 500 to 800 nm and the structure of the core / shell emits light in the region of 500 to 800 nm. In this case, the light emitting group emits light in an area of 400 or more and less than 500 nm so that the quantum dots emit white light as a whole.

The ligand includes a light emitting group and a linking group connecting the shell and the light emitting group, and may include a spacer between the linking group and the light emitting group, if necessary.

Structural formula 1 shows a schematic diagram of a white light emitting quantum dot according to an embodiment of the present invention.

[Formula 1]

In Structural Formula 1, A represents a light emitting group, L represents a spacer, and X represents a linking group.

In the white light emitting quantum dot of the present invention, a core / shell structure may be a known core / shell structure. For example, the core / shell structure described in Korean Patent Publication No. 2010-35466 may be used. More specifically, the core / shell structure may comprise a) a first element selected from group 2, 12, 13 and 14 and a second element selected from group 16; b) a first element selected from group 13 and a second element selected from group 15; And c) Group 14 elements; one material selected from the group consisting of, or these forms a structure of the core / shell, for example, MgO, MgS, MgSe, MgTe, CaO, CaS, CaSe, CaTe , SrO, SrS, SrSe, SrTe, BaO, BaS, BaSe, BaTE, ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, HgO, HgS, HgSe, HgTe, Al2O3, Al2S3, Al2E3, Al2Se3, Al2Se3 , Ga2S3, Ga2Se3, Ga2Te3, In2O3, In2S3, In2Se3, In2Te3, SiO2, GeO2, SnO2, SnS, SnSe, SnTe, PbO, PbO2, PbS, PbSe, PbTe, AlN, AlP, AlAs, AlSb, GaA , At least one selected from the group consisting of GaSb, InN, InP, InAs, InSb, BP, Si, and Ge, and those having a core / shell structure can be used.

The average diameter of the structure of the core / shell can be arbitrarily adjusted in consideration of the complementary color relationship, it can be used 1-12 nm. For example, the structure of the core / shell which emits light in the range of 500 to 800 nm or less has a diameter of 5-12 nm, The structure of the core / shell which emits light in the region of 400 or more and less than 500 nm may have a diameter of 1-3 nm. Preferably, the structure of the core / shell emits light in the region of 500 or more and 800 nm or less. It is good to use that.

In addition, in the white light emitting quantum dot of the present invention, a light emitting group capable of emitting a color that is complementary to the light emitting color of the core / shell structure contained in the ligand and emits white light as a whole is applied. For example, when the structure of the core / shell emits light in an area of 400 or more and less than 500 nm, the light emitting group emits light in an area of 500 or more and less than 800 nm and the structure of the core / shell is in an area of more than 500 and less than 800 nm. In the case of emitting light, the light emitting group uses a group that emits light in a range of 400 to less than 500 nm.

The light emitting group may be a known light emitting group, and for example, a fluorescent or phosphorescent light emitting group may be used. More specifically, the group for emitting light in the region of 400 or more and less than 500 nm may be one of the following FL1 to FL38, or PL1 to PL59, and the group for emitting the light in the region of 500 or more and less than 800 nm may be one of the following FL1 to FL38, Or PL1 to PL59.

In the following FL1 to FL38, or PL1 to PL59, * is a linking moiety, wherein the linking moiety may be connected to one or more of the substitution positions in parentheses, and R1 to R16 are each independently hydrogen; heavy hydrogen; halogen; Amino group; Nitrile group; Nitro group; C ₁ -C ₄₀ alkyl group which is unsubstituted or substituted with deuterium, halogen, amino group, nitrile group, nitro group; C ₂ -C ₄₀ alkenyl group; C ₁ ~ C ₄₀ Alkoxy group; C ₃ -C ₄₀ cycloalkyl group; C ₃ ~ C ₄₀ Heterocycloalkyl group; C ₆ -C ₄₀ aryl group; C ₃ ~ C ₄₀ heteroaryl group; An aralkyl group of C ₃ ~ C _40; C ₃ -C ₄₀ aryloxy group; C ₃ -C ₄₀ arylthio group or Si. Optionally two or more selected from R ₁ to R ₁₆ may combine with each other to form a ring, and may include S, N, O, and Si.

Preferably, the light emitting group is a group for emitting light in the region of 400 to less than 500 nm.

In addition, the linking group in the white light emitting quantum dot of the present invention is not particularly limited as long as the linking group is attached to the shell and can be connected to the light emitting group or the spacer, for example, a thiol group, a carboxyl group, an amine group, or a phosphine group. And at least one group selected from the group consisting of phosphide groups can be used. Preferably the linking group is a thiol group.

In addition, the white light emitting quantum dot of the present invention may further include a spacer between the light emitting group and the connecting group. The spacers may increase the number of light emitting groups that may be attached to the core / shell structure, and may facilitate dispersion of a ligand including a light emitting material into a solvent when preparing white light emitting quantum dots. Specifically, the spacer may be substituted or unsubstituted saturated or unsaturated C ₁ ~ C ₃₀ alkyl group, C ₃ ~ C ₄₀ cycloalkyl group, Si ₁ ~ Si ₃₀ silane may be used, but is not limited thereto.

Preferably, the present invention includes all of the light emitting group, the spacer and the linking group, for example, may have a structure as follows. In the following structures, the H portion of -SH is a portion that bonds with the core / shell structure.

Structures suitable for emitting light in the region of 400 to less than 500 nm:

Structure suitable for emitting light in the region of 500 to 800 nm

In the present invention, the size of the whole white light-emitting quantum dot including the light emitting group in the ligand can be arbitrarily adjusted, preferably 5 to 30 nm, more preferably 10-20 nm. In addition, in the present invention, the light emission intensity of the core / shell structure and the light emitting group can be arbitrarily adjusted. Preferably, the difference in the light emission intensity ratio of the core / shell structure and the light emitting group in the complementary color relationship is within 30%. Do. That is, when the emission intensity in the region of 400 to less than 500 nm is 1, the emission intensity of the region of 500 to 800 nm is preferably 0.7-1.3. When the intensity is 0.7 or less, the color purity is blue shifted. Red shifting may make it difficult to emit white light. In addition, when the emission intensity in the region of 500 to 800 nm is 1, the emission intensity of the region of 400 to 500 nm is preferably 0.7-1.3. When the intensity is 0.7 or less, the color purity is red shifted. As a result, the quantum dot may be difficult to emit white light.

Structural formula 2 shows a schematic diagram of a white light emitting quantum dot according to a specific example of the present invention, and since the light emitting material emits light in an area of 400 to less than 500 nm, the core / shell structure emits light in an area of 500 to 800 nm or less. As the structure of the size, the core may use CdSe and the shell may use ZnS.

[Formula 2]

The white light emitting quantum dots according to the present invention may be prepared by adding a ligand containing a light emitting group to a solution in which the structure of the core / shell is dispersed, followed by stirring. The preparation of the structure of the core / shell in the above can be used well known methods, of course, can be specifically followed the synthesis method described in FIG.

In addition, the ligand may be prepared by binding a linking group to the light emitting group or by including a spacer between the light emitting group and the linking group through the procedures of

Schemes

1 and 2 below.

Scheme 1

Scheme 2

In addition, in the method of attaching a ligand containing a light-emitting group to the structure of the core / shell, the stirring may be performed at room temperature to 100 ℃ for 0.1 to 100 hours.

The present invention also provides a light emitting device (QLED) using the white light emitting quantum dots and a method of manufacturing the same. In the present invention, the light emitting device may be applied to other known technologies except for the light emitting layer formed by using the white light emitting quantum dots according to the present invention.

For example, the light emitting device may be configured such that a substrate-a cathode-a light emitting layer formed of a white light emitting quantum dot according to the present invention-an anode may be sequentially formed, and an electron transport layer is further formed between the cathode and the light emitting layer. It is also possible to further form a hole transport layer between the light emitting layer and the anode. In addition, if necessary, a hole suppression layer may be further included between the electron transport layer and the light emitting layer, and a buffer layer may be formed between each layer.

In the present invention, a light emitting device (QLED) using a white light emitting quantum dot may be formed by a conventional manufacturing method, and the thickness of each organic film including the light emitting layer may be manufactured to be 30 to 100 nm.

In the case of using a white light emitting quantum dot according to the present invention as a light emitting layer, for example, in the organic electroluminescent device for electron transport, a buffer layer may be formed between each layer, and as a material of such a buffer layer, Materials may be used, for example copper phthalocyanine, polythiophene, polyaniline, polyacetylene, polypyrrole, polyphenylene vinylene, or Derivatives thereof may be used, but are not limited thereto.

As the material of the hole transport layer, a material commonly used may be used. For example, polytriphenylamine may be used, but is not limited thereto.

As the material of the electron transport layer, a material commonly used may be used, for example, polyoxadiazole may be used, but is not limited thereto.

A material commonly used as the material of the hole suppression layer may be used, for example, LiF, BaF ₂ or MgF ₂ may be used, but is not limited thereto.

More specifically, the light emitting device of the present invention may be manufactured according to the method described in FIG.

The light emitting device according to the present invention manufactured as described above can emit white light by itself without having a separate filter layer, so that the light emitting layer is formed of white light emitting quantum dots, so that the structure is simple and high in stability, compared to the conventional light emitting device. It has excellent color purity and high luminous efficiency.

Hereinafter, preferred examples are provided to help understanding of the present invention, but the following examples are merely to illustrate the present invention, and the scope of the present invention is not limited to the following examples.

Synthesis Example 1 Synthesis of 9-bromo-10-phenylanthracene (synthesis of luminescent material)

In an argon or nitrogen atmosphere, in a 250 ml flask, 4.2 g of 2-naphthalene boronic acid, 6.8 g of 9-bromoanthracene, 0.6 g of tetrakis (triphenylphosphine) palladium (0), 50 ml of toluene and 8.4 g of sodium carbonate Was dissolved in 50 ml of water, and the mixture was heated and stirred for 24 hours while refluxing. After the reaction, the mixture was cooled to room temperature and the precipitated crystals were separated by filtration. It was recrystallized from toluene to give 7.5 g of crystals.

In an argon or nitrogen atmosphere, in a 250 ml flask, 7.5 g of the crystal and 100 ml of dehydrated DMF (dimethylformamide) were placed, heated to 80 ° C., the raw material was dissolved, and then N-brominated at 50 ° C. 4.8 g of succinimide was added and stirred for 2 hours. After the reaction was completed, the reaction solution was poured into 200 ml of purified water, and the precipitated crystals were separated by filtration. It was recrystallized from toluene to give 6.8 g of crystals.

Synthesis Example 2

9- (10-bromodesyl) -10-phenylanthracene (spacer synthesis)

8 g of 9-bromo-10-phenylanthracene was dissolved in 300 ml of anhydrous diethyl ether. 18 ml of n- BuLi (2M) was slowly added thereto at 0 ° C. After holding for 1 hour at 0 ° C., 21.6 ml of 1.10-Dibromodekene was added. After 30 minutes, the mixture was stirred at reflux for 2 hours. If the reaction did not proceed anymore, after cooling to room temperature, 80 ml of distilled water was added. The organic layer was collected and the water layer was extracted three times with 40 ml of ethyl ether. After water removal with anhydrous magnesium sulfate, hexane was separated by mobile phase to give 5.7 g (50%) of light green oily 9- (10-bromodesyl) -10-phenylanthracene.

¹ H NMR (CDCl ₃ , 400 MHz): 8.32 (2H, d), 7.63 (2H, d), 7.59 (9H, m), 3.92 (2H, t), 3.65 (2H, t), 1.70-1.68 ( 2H, m), 1.64-1.60 (4H, m), 1.52 (10H, m)

Synthesis Example 3 Synthesis of Compound DJ-A-1

4 g (1 eq) of 9- (10-bromodesyl) -10-phenylanthracene and 1.3 g (2 eq) of thiourea were dissolved in 50 ml of anhydrous ethanol and stirred under reflux for 4 hours. 50 ml of 6 M sodium hydroxide was added thereto, and the mixture was stirred under reflux for 2 hours. If the reaction did not proceed any more, ethanol was removed and extracted three times with 30 ml of ethyl acetate. After washing with brine solution, water was removed with anhydrous magnesium sulfate, and CHCl ₃ was separated by mobile phase to give 1.4 g (39%) of light green oily 10- (10-phenylanthrace-9-yl) decane-1-thiol.

¹ H-NMR (CDCl ₃ , Varian 400 MHz): δ 1.26-1.38 (6H, m), 1.43-1.46 (4H, m), 1.62-1.66 (2H, m), 1.85-1.90 (4H, m), 3.42 ( 2H, t, J = 6.8 Hz), 3.64-3.69 (2H, m), 7.31-7.35 (2H, m), 7.40-7.42 (2H, m), 7.48-7.59 (5H, m), 7.06 (2H, d, J = 8.8 Hz), 8.33 (2H, d, J = 9.2 Hz).

LC-MS (LC: Agilent 1200, MS: LCQ Advantage Max): Mobile phase from 0% [water + 0.01% HFBA + 1.0% IPA] and 100% [CH ₃ CN + 0.01% HFBA + 1.0% IPA] to0% [water + 0.01% HFBA + 1.0% IPA] and100% [CH ₃ CN + 0.01% HFBA + 1.0% IPA] in6.0min) .Purityis99.72%, Rt = 2.48min; MSCalcd.: 426.24; MSFound426.2 [ M].

Synthesis Example 4 Synthesis of Compound DJ-A-2

Synthesis Example 3 was repeated in Synthesis Example 1, except that 1,5-dibrompentane was used instead of 1.10-dibromodeken in Synthesis Example 2, and Pale yellow DJ-A-2 was synthesized.

¹ H-NMR (CDCl ₃ , Varian 400 MHz): δ 1.45 (1H, t, J = 7.6 Hz), 1.74-1.81 (4H, m), 1.87-1.92 (2H, m), 2.60 (2H, q, J = 7.6 Hz), 3.66-3.70 (2H, m), 7.32-7.35 (2H, m), 7.40-7.42 (2H, m), 7.48-7.54 (3H, m), 7.55-7.59 (2H, m), 7.06 (2H, d, J = 8.4 Hz), 8.31 (2H, d, J = 8.8 Hz).

LC-MS (LC: Agilent 1200, MS: LCQ Advantage Max): Mobile phase from 10% [water + 0.01% HFBA + 1.0% IPA] and 90% [CH ₃ CN + 0.01% HFBA + 1.0% IPA] to5% [water + 0.01% HFBA + 1.0% IPA] and 95% [CH ₃ CN + 0.01% HFBA + 1.0% IPA] in6.0min) .Purityis99.52%, Rt = 2.61min; MSCalcd.: 356.16; MSFound356.2 [ M].

The overall reaction schematic of Synthesis Examples 3 and 4 is as follows.

Synthesis Example 5 Synthesis of Compound DJ-A-3

In Synthesis Example 1, the procedure of Synthesis Example 3 was repeated, except that 9- (4-bromopheneyl) -10-phenylanthracene was used instead of 9-bromo-10-phenyl anthracene in Synthesis Example 1, and white solid DJ-A-3 was used. Synthesized.

¹ H-NMR (CDCl ₃ , Varian 400 MHz): δ 1.32-1.45 (12H, m), 1.60-1.63 (2H, m), 1.75-1.78 (2H, m), 2.52 (2H, q, J = 7.6 Hz) 2.75-2.79 (2H, m), 7.30-7.32 (4H, m), 7.75-7.41 (4H, m), 7.46-7.48 (2H, m), 7.53-7.61 (3H, m), 7.6-7.73 ( 4H, m).

LC-MS (LC: Agilent 1200, MS: LCQ Advantage Max): Mobile phase from 0% [water + 0.01% HFBA + 1.0% IPA] and 100% [CH ₃ CN + 0.01% HFBA + 1.0% IPA] to0% [water + 0.01% HFBA + 1.0% IPA] and100% [CH ₃ CN + 0.01% HFBA + 1.0% IPA] in10min) .Purityis99.62%, Rt = 3.94min; MSCalcd.: 502.27; MSFound502.2 [M] .

Synthesis Example 6 Synthesis of Compound DJ-A-4

1,5-dibrompentane was used instead of 1.10-dibromodeken in Synthesis Example 5, and Pale yellow solid DJ-A-4 was synthesized.

¹ H-NMR (CDCl ₃ , Varian 400 MHz): δ 1.39 (1H, t, J = 7.6 Hz), 1.54-1.60 (2H, m), 1.73-1.82 (2H, m), 2.61 (2H, q, J = 7.6 Hz), 2.79-2.82 (2H, m), 7.31-7.33 (4H, m), 7.39-7.40 (4H, m), 7.47-7.49 (2H, m), 7.54-7.60 (3H, m), 7.07 -7.73 (4H, m).

LC-MS (LC: Agilent 1200, MS: LCQ Advantage Max): Mobile phase from 5% [water + 0.01% HFBA + 1.0% IPA] and 95% [CH ₃ CN + 0.01% HFBA + 1.0% IPA] to0% [water + 0.01% HFBA + 1.0% IPA] and100% [CH ₃ CN + 0.01% HFBA + 1.0% IPA] in6.0min) .Purityis99.58%, Rt = 2.85min; MSCalcd.: 432.19; MSFound432.2 [ M].

The overall reaction schematics of Synthesis Examples 5 and 6 are as follows.

Synthesis Example 7 Synthesis of Compound DJ-A-5

In Synthesis Example 1, the procedure of Synthesis Example 3 was repeated, except that 9-brom-10- (2-napthyl) anthracene was used instead of 9-bromo-10-phenyl anthracene in Synthesis Example 1, yellow solid DJ-A-5 Was synthesized.

¹ H-NMR (CDCl ₃ , Varian 400 MHz): δ 1.32-1.42 (12H, m), 1.59-1.65 (2H, m), 1.75-1.81 (2H, m), 2.54 (2H, q, J = 7.6 Hz) , 2.79 (2H, t, J = 7.6 Hz), 7.28-7.35 (4H, m), 7.39-7.43 (4H, m), 7.57-7.62 (3H, m), 7.69-7.76 (4H, m), 7.90 -7.93 (1H, m), 7.98 (1H, s), 8.01-8.04 (1H, m), 8.07 (1H, d, J = 8.4 Hz).

LC-MS (LC: Agilent 1200, MS: LCQ Advantage Max): Mobile phase from 0% [water + 0.01% HFBA + 1.0% IPA] and 100% [CH ₃ CN + 0.01% HFBA + 1.0% IPA] to0% [water + 0.01% HFBA + 1.0% IPA] and100% [CH ₃ CN + 0.01% HFBA + 1.0% IPA] in10min) .Purityis99.84%, Rt = 4.95min; MSCalcd.: 552.29; MSFound552.2 [M] .

The overall reaction schematic of Synthesis Example 7 is as follows.

Synthesis Example 8 Synthesis of Compound DJ-A-6

The procedure of Synthesis Example 7 was repeated, except that 1,5-dibrompentane was used instead of 1.10-dibromodeken in Synthesis Example 2, and yellow solid DJ-A-6 was synthesized.

¹ H-NMR (CDCl ₃ , Varian 400 MHz): δ 1.39 (1H, t, J = 7.2 Hz), 1.62-1.54 (2H, m), 1.85-1.71 (4H, m), 2.61 (2H, q, J = 7.2 Hz), 2.83-2.79 (2H, m), 7.36-7.28 (4H, m), 7.42 (4H, s), 7.63-7.59 (3H, m), 7.76-7.70 (4H, m), 7.93-7.91 (1H, m), 7.98 (1H, s), 8.04-8.02 (1H, m), 8.07 (1H, d, J = 8.4 Hz).

LC-MS (LC: Agilent 1200, MS: LCQ Advantage Max): Mobile phase from 0% [water + 0.01% HFBA + 1.0% IPA] and 100% [CH ₃ CN + 0.01% HFBA + 1.0% IPA] to0% [water + 0.01% HFBA + 1.0% IPA] and100% [CH ₃ CN + 0.01% HFBA + 1.0% IPA] in6.0min) .Purityis99.76%, Rt = 2.23min; MSCalcd.: 482.21; MSFound482.2 [ M].

The overall reaction schematic of Synthesis Example 8 is as follows.

Synthesis Example 9 CdSe / ZnS Synthesis

It manufactured by the method shown in the schematic diagram of FIG. More specifically, 0.4 mmol CDO (99.99%) of cadmium oxide, 4 mmol (99.9%, powder) of zinc acetate and 5.58 mL of oleic acid (OA) were placed in a 100 mL three-necked flask at 150 ° C. for 30 minutes under nitrogen atmosphere. Heated during. Then put 1 mL of 1 octadecene (ODE) and increase the temperature to 310 ℃. 3 mL (TOP) of trioctylphosphine, 1 mmol of selenium (SE), and 2.3 mmol of sulfur (S) were rapidly injected into the flask. The reaction temperature was maintained at 310 ℃ for 10 minutes and then cooled to room temperature. The resulting quantum dots were purified with 20 mL of chloroform and excess acetone (at least 3 times). Quantum dots were redispersed in chloroform or hexane at a concentration of 5.0 mg / mL.

Synthesis Example 10 Synthesis of ZnO nanoparticles

ZnO nanoparticles are used as the electron transport layer, ZnO nanoparticle synthesis was used the following method. That is, 30 mL of zinc acetate dimethyl sulfoxide (DMSO, 0.5 M) was added, and tetramethylammonium hydride (TMAH, 0.55 M) mixture was stirred in ethanol for 1 hour. It was then centrifuged and washed with ethanol and excess acetone mixture. The synthesized ZnO nanoparticles were dispersed in ethanol at a concentration of 30 mg / mL and used as an electron transport layer material for the LED manufacturing apparatus.

Example 1 White Light Emitting Quantum Dot Synthesis (Ligand Exchange)

In the same manner as in FIG. 4, white light-emitting quantum dots were synthesized. That is, a CdSe / ZnS solution (0.2 ml, 5 mg / ml in hexane) was prepared using the quantum dots prepared in Synthesis Example 9, and a light emitting material (0.5 ml, 3 mM in hexane) prepared in Synthesis Example 3 was added thereto. Stirred at room temperature for 30 minutes. Methanol was added to the reaction flask to solidify and centrifuged to produce white light-emitting quantum dots. Ligand exchange results were confirmed by IR DATA, UV absorption and PL spectra. 5 is an FT-IR spectra of the prepared white light emitting quantum dots, (a) shows Synthesis Example 3 (DJ-A-1), and (b) shows Example 1 (DJ-A-1 + CdSe / ZnS). It is measured. 6 is UV absorption and PL spectra, (a) shows Synthesis Example 8 (QDs), (b) shows Synthesis Example 3 and (c) Example 1;

Example 2 Fabrication of QD-LED Device

QD-LED was fabricated on an indium tin oxide coated glass (ITO / glass) substrate (sheet resistance <10Ω / □). The ITO glass was washed with acetone and isopropyl alcohol using ultrasonic waves for 1 minute and plasma treated with argon / oxygen for 1 minute. Furthermore, poly (3,4-ethylene dioxythiophene): poly (styrene sulfonate) (PEDOT: PSS, Baytron P AI 4083) was diluted with isopropyl alcohol in a 9: 1 volume ratio and spin-coated at 4,000 rpm for 30 seconds. PEDOT: PSS coated ITO glass was baked in a hot plate at 120 ° C. for 10 minutes in air.

The coated substrate was spin-coated with polyvinylcarbazole (PVK, 0.01 g / mL of chlorobenzene) at 3,000 rpm for 30 seconds in a glove box filled with N ₂ , followed by baking the substrate at 180 ° C. for 30 minutes, Used as a hole transport layer. As a light emitting layer, the white light emitting quantum dot solution prepared in Example 1 was spin coated for 1,500 rpm for 20 seconds.

Next, the ZnO nanoparticle (30 mg / mL) solution was spin coated at 1,500 rpm for 30 seconds, and the substrate was baked at 150 ° C. for 30 minutes. Finally, the multilayer thin film substrate was placed in a high vacuum deposition chamber (background pressure ˜5 × 10 ⁻⁶ torr) and an aluminum cathode (100 nm thick) was deposited.

[Comparative Example 1] Fabrication of Orange QD-LED Device

In Example 2, instead of the white light emitting quantum dots, Orange light emitting quantum dots of Synthesis Example 9 was used as the light emitting layer.

[Comparative Example 2] Blue OLED Device Fabrication

In Example 2, DJ-A-1 of Synthesis Example 3 was used as a light emitting layer instead of the white light emitting quantum dots.

The IVL characteristics and EL spectra of the electroluminescent (EL) devices of Example 2 and Comparative Examples 1 and 2 prepared above were confirmed. The maximum light emission intensity is 2,000 cd / m 2, and the light emission efficiency of each device is shown in Table 1 and Graph 7 below. (A) of FIG. 7 shows current density and luminance versus driving voltage, and (b) shows luminance power efficiency versus luminance.

Table 1

Color of LED	V _T (V)	λ _max (nm)	FWHM (nm)	L _max (cd / m ² )	η _A (cd / A)
Example 2	4.2	470, 595	40	2015	0.19
Comparative Example 1	4.9	590	39.2	1790	1.27
Comparative Example 2	4.4	460	27.8	1502	0.29

In addition, the normalized electroluminescence spectra of the devices prepared in Example 2 and Comparative Examples 1 and 2 were measured. The results are shown in FIG. In Figure 8 (b) is a light source of Comparative Example 1, (c) is a light source of Comparative Example 2, (d) is an Electroluminecence (EL) spectra of the LED used as the light source of Example 2, the full width at half maximum (FWHM), respectively, Orange and white were 27.8 nm, 39.2 nm, and (42.2 nm, 39.3 nm).

Claims

A quantum dot comprising a structure of the core / shell and a ligand attached to the surface of the shell,

The ligand comprises a light emitting group,

The luminescent group of the core / shell structure and the ligand is a quantum dot comprising a structure of the white light emitting quantum dot core / shell and a ligand attached to the surface of the shell, characterized in that the light emitting a color complementary to each other to emit white light as a whole.
The method of claim 1,

The core / shell structure emits light in a range of 400 to 500 nm or less, or emits light in a range of 500 to 800 nm or less,

When the structure of the core / shell emits light in the region of 400 to less than 500 nm, the light emitting group emits light in the region of 500 to 800 nm and the structure of the core / shell emits light in the region of 500 to 800 nm. In this case, the light emitting group emits white light by emitting light in the region of 400 or more and less than 500 nm.
The method of claim 1,

The ligand is a quantum dot for emitting white light, characterized in that it comprises a light emitting group and a linking group connecting the light emitting group with the shell.
The method of claim 3,

The ligand is a quantum dot for emitting white light, characterized in that further comprising a spacer between the linking group and the light emitting group.
The method of claim 1,

The light emitting group is a quantum dot for emitting white light, characterized in that at least one selected from the group consisting of:

In FL1 to FL38, or PL1 to PL59, * is a linking moiety, wherein the linking moiety may be connected to one or more of the substitution positions in parentheses, and R1 to R16 are each independently hydrogen; heavy hydrogen; halogen; Amino group; Nitrile group; Nitro group; C 1 -C 40 alkyl group which is unsubstituted or substituted with deuterium, halogen, amino group, nitrile group, nitro group; C 2 -C 40 alkenyl group; C 1 ~ C 40 Alkoxy group; C 3 -C 40 cycloalkyl group; C 3 ~ C 40 Heterocycloalkyl group; C 6 -C 40 aryl group; C 3 ~ C 40 heteroaryl group; An aralkyl group of C 3 ~ C 40; C 3 -C 40 aryloxy group; C 3 -C 40 arylthio group or Si. Optionally, two or more selected from R1 to R16 may combine with each other to form a ring and may include S, N, O, and Si.
The method of claim 1,

The light emitting group is a quantum dot for emitting white light, characterized in that for emitting light in the region of 400 to less than 500 nm.
The method of claim 1,

The light emitting group is a quantum dot for emitting white light, characterized in that for emitting light of 500 to 800 nm region.
The method of claim 2,

The linking group is a quantum dot emitting white light, characterized in that at least one selected from the group consisting of a thiol group, a carboxy group, an amine group, a phosphine group, and a phosphide group.
The method of claim 4, wherein

The spacer is a quantum dot that emits white light, characterized in that the substituted or unsubstituted saturated or unsaturated C 1 ~ C 30 alkyl group, C 3 ~ C 40 cycloalkyl group, Si 1 ~ Si 30 silane.
The method of claim 4, wherein

A quantum dot emitting white light, characterized in that the ligand is one of those represented by the following structures:

In the above structures, the H portion of -SH is a portion that bonds with the core / shell structure.
The method of claim 4, wherein

A quantum dot emitting white light, characterized in that the ligand is one of those represented by the following structures:

In the above structures, the H portion of -SH is a portion that bonds with the core / shell structure.
The method of claim 1,

Particle diameter of the quantum dot is a quantum dot emitting white light, characterized in that 5 to 30 nm.
The method of claim 1,

And a luminous intensity of the luminous group of the ligand in complementary relation when the luminous intensity of the core / shell structure is 1 is 0.7-1.3.
A method for producing a white light-emitting quantum dot according to claim 1, comprising adding a ligand containing a light-emitting group to a solution in which the structure of the core / shell is dispersed, and then stirring.
The method of claim 14,

The stirring is a method of producing a white light emitting quantum dot, characterized in that made for 0.1 to 100 hours at a temperature of room temperature to 100 ℃.
In the light emitting device,

A light emitting device comprising a white light emitting quantum dot of claim 1 as a light emitting material.
In the manufacturing method of the light emitting device,

A method of manufacturing a light emitting device comprising the step of forming a light emitting layer from the white light emitting quantum dots of claim 1.