JP6396297B2 - White light emitting quantum dots - Google Patents

Description

  The present invention relates to a white light-emitting quantum dot, and more particularly to a white light-emitting quantum dot capable of emitting white light by a single quantum dot and a method for manufacturing the same.

  A quantum dot is a nano-sized semiconductor material and exhibits a quantum restriction effect. When such a quantum dot receives light from an excitation source and reaches an energy excited state, Voluntarily releases energy by the corresponding energy band gap. In addition, by adjusting the size of the quantum dot and adjusting the corresponding band gap, the electrical and optical characteristics can be adjusted. Therefore, the emission wavelength can be adjusted only by adjusting the size of the quantum dot, which is excellent. Therefore, the present invention can be applied to various elements such as a light emitting element or a photoelectric conversion element.

  Quantum dots as light-emitting elements that have been studied in the past have been disclosed to emit only the wavelength of one color region band as in US Pat. No. 6,501,091 and WO2012 / 013272, but only one quantum dot is disclosed. In order to realize white light, it is difficult to provide a separate filter layer to change the wavelength of the emitted light. Regardless, the fact is that no single quantum dot itself emits white light.

  In order to solve the above-mentioned problems, the present invention can produce white light emitting quantum dots that can emit white light by themselves and exhibit excellent color purity, high stability, and high luminous efficiency, and the production thereof. It is an object to provide a method and a light emitting device including the method.

In order to achieve the above object, the present invention provides:
A quantum dot comprising a core / shell structure and a ligand attached to the surface of the shell, comprising:
The ligand comprises a luminescent group;
The light emitting group of the core / shell structure and the ligand emits a color complementary to each other to emit white light as a whole, thereby providing a white light emitting quantum dot.

Preferably, the core / shell structure may emit light having a wavelength range of 400 to 500 nm, or may emit light having a wavelength range of 500 to 800 nm,
When the core / shell structure emits light in the 400 to 500 nm region band, the light emitting group emits light in the 500 to 800 nm region band, and the core / shell structure has the 500 to 800 nm region. In the case of emitting band light, the light emitting group may be quantum dots that emit light in the 400 to 500 nm region and emit white light as a whole.

  The present invention also provides a method for producing white light-emitting quantum dots, comprising a step of adding a ligand containing a light-emitting group to a solution in which a core / shell structure is dispersed and then stirring the solution.

  According to another aspect of the present invention, there is provided a light emitting device including the white light emitting quantum dot as a light emitting material.

  According to another aspect of the present invention, there is provided a method for 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 themselves without a separate filter layer, when applied to a light emitting element, the structure is simple but compared with a conventional light emitting element. And excellent color purity, high stability and high luminous efficiency.

1 is a schematic diagram of a white light emitting quantum dot according to an embodiment of the present invention. FIG. 3 is a schematic view of a white light emitting quantum dot according to another embodiment of the present invention. It is a CdSe / ZnS synthetic schematic diagram used for white light emitting quantum dots according to an embodiment of the present invention. It is a synthetic schematic diagram of white light emitting quantum dots according to an embodiment of the present invention. 4 is an FT-IR spectrum of a white light emitting quantum dot according to an embodiment of the present invention. 2 is a UV absorption and PL spectrum of a white light emitting quantum dot according to an embodiment of the present invention. 3 is a graph showing the device luminous efficiency of white light emitting quantum dots according to an embodiment of the present invention. 2 shows an emission spectrum of a white light emitting quantum dot according to an embodiment of the present invention.

The present invention will be described in detail below.
The white light emitting quantum dot of the present invention is a quantum dot including a core / shell structure and a ligand attached to a surface of the shell, wherein the ligand includes a light emitting group, and the core / shell structure and the ligand emit light. A group is a white light-emitting quantum dot that emits white light as a whole by emitting colors that are complementary to each other. That is, a single quantum dot is a white light emitting quantum dot which can emit white light as a whole by including a core / shell structure having a complementary color relationship and a ligand containing a light emitting group. It is characterized by that.

In the present invention, the emission wavelength of a ligand including a core / shell structure and a light emitting group having a complementary color relationship can be arbitrarily adjusted. As a specific example, the core / shell structure has a wavelength range of 400 to 500 nm. Can emit light in the band, or can emit light in the range of 500 to 800 nm,
When the core / shell structure emits light in the 400 to 500 nm region band, the light emitting group emits light in the 500 to 800 nm region band, and the core / shell structure has the 500 to 800 nm region. In the case of emitting band light, the light emitting group emits light in the 400 to 500 nm region band, and the quantum dots can emit white light as a whole.

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

The following structural formula 1 shows a schematic diagram of a white light emitting quantum dot according to an embodiment of the present invention.
In the structural formula 1, A represents a light emitting group, L represents a spacer, and X represents a connected group.

  As the core / shell structure of the white light-emitting quantum dot of the present invention, a known core / shell structure can be used. For example, the core / shell structure described in Korean Patent Publication No. 2010-35466 is used. You can also. More specifically, the core / shell structure is selected from a) a first element selected from Group 2, 12, 12, 13 and 14 and a second element selected from Group 16; b) selected from Group 13 As an example, one substance selected from the group consisting of a first element and a second element selected from group 15; and c) a group 14 element; or a substance formed of a core / shell structure. Examples thereof include 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, Al2Se3, Al2Te3, Ga2O3, Ga2S3, G 2Se3, Ga2Te3, In2O3, In2S3, In2Se3, In2Te3, SiO2, GeO2, SnO2, SnS, SnSe, SnTe, PbO, PbO2, PbS, PbSe, PbTe, AlN, AlP, AlAs, AlSb One or more types selected from the group consisting of InN, InP, InAs, InSb, BP, Si, and Ge can be used in which these form a core / shell structure.

  The average diameter of the core / shell structure can be arbitrarily adjusted in consideration of complementary colors, and those having a diameter of 1 to 12 nm can be used. As an example, a core / shell structure that emits light in the 500 to 800 nm region band has a diameter of 5-12 nm, and a core / shell structure that emits light in the 400 to less than 500 nm region band has 1-3 nm. The core / shell structure preferably emits light in the range of 500 to 800 nm.

  In addition, the white light emitting quantum dots of the present invention emit light of a color complementary to the light emission color of the core / shell structure contained in the ligand, so that the quantum dots can emit white light as a whole. The lighting group is applied. As an example, when the core / shell structure emits light in the 400 nm to 500 nm nm region band, the light emitting group emits light in the 500 nm to 800 nm nm region band, and the core / shell structure has 500 nm or more. When light in the 800 nm or less nm band is emitted, a group that emits light in the 400 to 500 nm band is used.

  As the light emitting group, a known light emitting group can be used. For example, a fluorescent or phosphorescent light emitting group can be used. More specifically, the group that emits light in the 400 to 500 nm region band may be one of the following FL1 to FL38 or PL1 to PL59, and the group that emits light in the 500 to 800 nm region band: Can 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 is linked to one or more of the substitution positions in parentheses, and R1 to R16 are each independently hydrogen; deuterium; halogen; amino group; nitrile group, a nitro group, an alkenyl group of C 2 _{-C 40;;} deuterium, halogen, amino group, nitrile group, alkyl group of _C 1 _{-C 40} substituted or unsubstituted nitro group _{C 1} heteroaryl group _C 3 ~C _40;; aryl group C 6 _{-C 40;} heterocycloalkyl group C 3 _{-C 40;} cycloalkyl group C 3 _{-C 40;} alkoxy groups -C _{40 C} 3 ~ A C ₄₀ aralkyl group; a C ₃ -C ₄₀ aryloxy group; a C ₃ -C ₄₀ arylthio group or Si. Two or more optionally selected from R _{1 to} R ₁₆ may be bonded to each other to form a ring, and may include S, N, O, and Si.

  Preferably, the light emitting group is a group that emits light in a range of 400 to 500 nm.

  Further, in the white light emitting quantum dots of the present invention, the linking group is not particularly limited as long as it is a linking group attached to the shell and connected to the luminescent group or the spacer. For example, a thiol group, a carboxy group, an amine group A group selected from at least one selected from the group consisting of a phosphine group and a phosphide group can be used. Preferably, the linking group is a thiol group.

The white light emitting quantum dot of the present invention may further include a spacer between the light emitting group and the connection group. The spacers can increase the number of light emitting groups attached to the core / shell structure, and can facilitate dispersion of a ligand containing a light emitting material in a solvent when manufacturing white light emitting quantum dots. Specifically, the spacer can be used substituted or unsubstituted, saturated or unsaturated _C 1 _{-C 30} alkyl _group, cycloalkyl group C 3 _{-C 40,} the silane _Si 1 ~Si _30, which It is not limited to.

  Preferably, the present invention includes all the light emitting groups, spacers, and connection groups, and may have the following structure as an example. In the following structure, the H part of -SH is a part that binds to the core / shell structure.

A structure suitable for emitting light in the range of 400 to 500 nm:

A structure suitable for emitting light in the range of 500 to 800 nm:

  In the present invention, the size of the whole white light-emitting quantum dot containing a light-emitting group as a ligand can be arbitrarily adjusted, and is preferably 5 to 30 nm, more preferably 10 to 20 nm. In the present invention, the light emission intensity of the core / shell structure and the light emission group can be arbitrarily adjusted. Preferably, the difference in light emission intensity ratio between the core / shell structure and the light emission group which are complementary in the present invention is 30. % Is preferable. That is, when the emission intensity in the 400-500 nm region band is 1, the emission intensity in the 500-800 nm region band is preferably 0.7-1.3, and the color purity is 0.7 or less. If blue shift is performed and the color purity is 1.3 or more, the color purity may be red shifted, and it may be difficult for the entire quantum dot to emit white light. When the emission intensity in the 500 to 800 nm region band is 1, the emission intensity in the 400 to less than 500 nm region band is preferably 0.7 to 1.3, and is 0.7 or less. If the color purity is red shift and the color purity is 1.3 or more, the color purity may be blue shift and it may be difficult for the quantum dots to emit white light as a whole.

The following structural formula 2 shows a schematic diagram of a white light emitting quantum dot according to a specific example of the present invention, and the core / shell structure because the luminescent material emits light in the 400 to 500 nm region band. Is a structure that emits light in the range of 500 to 800 nm, and the core can be CdSe and the shell can be ZnS.

  The white light emitting quantum dots according to the present invention can be manufactured by adding a ligand containing a light emitting group to a solution in which a core / shell structure is dispersed, and then stirring. In the above, the core / shell structure can be manufactured by a known method, and can be specifically manufactured by the synthesis method shown in FIG.

In addition, a ligand including a luminescent group may be manufactured by combining a linking group with the luminescent group or by adding a spacer between the luminescent group and the linking group through the processes of the following reaction formulas 1 and 2. Can do.

  In the method of attaching a ligand containing a light emitting group to a core / shell structure, the stirring can be performed at a temperature of room temperature to 100 ° C. for 0.1 to 100 hours.

  Moreover, this invention provides the light emitting element (QLED) using the said white light emission quantum dot, and its manufacturing method. In the present invention, other known techniques can be applied to the light emitting device except for the light emitting layer formed using the white light emitting quantum dots according to the present invention.

  As an example, according to one embodiment, the light emitting device may be configured such that a substrate, a cathode, a light emitting layer formed of white light emitting quantum dots according to the present invention, and an anode are sequentially formed. An electron transport layer can be further formed between the layers, and a hole transport layer can be further formed between the light emitting layer and the anode. Further, if necessary, a hole suppression layer can be further included between the electron transport layer and the light emitting layer, and a buffer layer can be formed between the layers.

  In the present invention, a light emitting device (QLED) using white light emitting quantum dots can be formed by an ordinary manufacturing method, and each organic film including the light emitting layer can be manufactured to have a thickness of 30 to 100 nm. it can.

  When used as a light-emitting layer using white light-emitting quantum dots according to the present invention, for example, in the organic electroluminescent device for electron transport, a buffer layer can be formed between each layer, and such a buffer layer is usually used as a material. For example, copper phthalocyanine, polythiophene, polyaniline, polyacetylene, polypyrrole, ne, or polyphenylene vinyl. However, the present invention is not limited to this.

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

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

As the material for the hole suppression layer, a commonly used substance can be used. For example, LiF, BaF ₂ or MgF ₂ can be used, but the material is not limited thereto.
More specifically, the light emitting device of the present invention can be manufactured by 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 a separate filter layer, and has a simple structure because the light emitting layer is formed of white light emitting quantum dots. However, it has high stability and has excellent color purity and high luminous efficiency compared to conventional light emitting elements.

  Hereinafter, preferred examples will be presented for the understanding of the present invention. However, the following examples are merely illustrative of 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 a 250 ml flask under argon or nitrogen atmosphere, 4.2 g of 2-naphthaleneboronic acid, 6.8 g of 9-bromoanthracene, 0.6 g of tetrakis (triphenylphosphine) palladium (0), 50 ml of toluene and sodium carbonate 8. A solution prepared by dissolving 4 g in 50 ml of water was added, and the mixture was heated and stirred for 24 hours while refluxing. After the reaction, it was cooled to room temperature and the precipitated crystals were separated by filtration. This was recrystallized with toluene to obtain 7.5 g of crystals.
In a 250 ml flask under argon or nitrogen atmosphere, 7.5 g of the above crystals and 100 ml of dehydrated DMF (dimethylformamide) were added and heated at 80 ° C. to dissolve the raw materials, and then N-bromosuccinic acid at 50 ° C. 4.8 g of imide was added and stirred for 2 hours. After completion of the reaction, the reaction solution was poured into 200 ml of purified water, and the precipitated crystals were separated by filtration. This was recrystallized from toluene to obtain 6.8 g of crystals.

[Synthesis Example 2]
9- (10-bromodecyl) -10-phenylanthracene (spacer synthesis)
8 g of 9-bromo-10-phenylanthracene was dissolved in 300 ml of anhydrous diethyl ether. Here, 18 ml of n-BuLi (2M) was gradually added at 0 ° C. After maintaining at 0 ° C. for 1 hour, 21.6 ml of 1.10-dibromodecane was added. After 30 minutes, the mixture was stirred at reflux for 2 hours. If the reaction was not carried out any further, 80 ml of distilled water was added after cooling to room temperature. The organic layer was collected and the aqueous layer was extracted 3 times with 40 ml of ethyl ether. After removing moisture with anhydrous magnesium sulfate, hexane was used as a mobile phase and the column was separated to obtain 5.7 g (50%) of light green oily 9- (10-bromodecyl) -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] Compound DJ-A-1 Synthesis 9- (10-bromodecyl) -10-phenylanthracene 4 g (1 eq) and thiourea 1.3 g (2 eq) were dissolved in 50 ml of absolute ethanol and stirred at reflux for 4 hours. To this, 50 ml of 6M sodium hydroxide was added and stirred under reflux for 2 hours. If the reaction was not carried out any further, the ethanol was removed and then extracted three times with 30 ml of ethyl acetate. After washing with a brine solution, water was removed with anhydrous magnesium sulfate, CHCl ₃ was used as a mobile phase, and the column was separated to obtain a pale green oily 10- (10-phenylanthracen-9-yl) decane-1-thiol 1.4 g. (39%) was obtained.

[Synthesis Example 4] Synthesis of Compound DJ-A-2 The above-mentioned Synthesis Example 1 and Synthesis Example 3] were repeated except that 1,5-dibromopentane was used instead of 1.10-dibromodecane in Synthesis Example 2. Pale yellow DJ-A-2 was synthesized.

1H-NMR (CDCl3, Varian400MHz): δ 1.45 (1H, t, J = 7.6Hz), 1.74-1.81 (4H, m), 1.87-1.92 (2H, m), 2.60 (2H, q, J = 7.6Hz ), 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), 7.66 (2H , d, J = 8.4Hz), 8.31 (2H, d, J = 8.8Hz).
LC-MS (LC: Agilent 1200, MS: LCQ Advantage Max): Mobile phase from 10% [water + 0.01% HFBA + 1.0% IPA] and 90% [CH3CN + 0.01% HFBA + 1.0% IPA] to5% [water + 0.01% HFBA + 1.0% IPA] and95% [CH3CN + 0.01% HFBA + 1.0% IPA] in6.0min) .Purityis99.52%, Rt = 2.61min; MSCalcd.: 356.16; MSFound356.2 [M].

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

[Synthesis Example 5] Synthesis of Compound DJ-A-3 The same procedure as in Synthesis Example 3 was repeated in Synthesis Example 1, except that 9- (4-bromophenyl) was used instead of 9-bromo-10-phenylanthracene in Synthesis Example 1. Using -10-phenylanthracene, white solid DJ-A-3 was synthesized.

1H-NMR (CDCl3, Varian400MHz): δ 1.32-1.45 (12H, m), 1.60-1.63 (2H, m), 1.75-1.78 (2H, m), 2.52 (2H, q, J = 7.6Hz), 2.75 -2.79 (2H, m), 7.30-7.32 (4H, m), 7.35-7.41 (4H, m), 7.46-7.48 (2H, m), 7.53-7.61 (3H, m), 7.66-7.73 (4H, m).
LC-MS (LC: Agilent 1200, MS: LCQ Advantage Max): Mobile phase from 0% [water + 0.01% HFBA + 1.0% IPA] and 100% [CH3CN + 0.01% HFBA + 1.0% IPA] to0% [water + 0.01% HFBA + 1.0% IPA] and100% [CH3CN + 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 In Synthesis Example 5, 1,5-dibromopentane was used instead of 1.10-dibromodecane to synthesize pale yellow solid DJ-A-4. did.

1H-NMR (CDCl3, Varian400MHz): δ 1.39 (1H, t, J = 7.6Hz), 1.54-1.60 (2H, m), 1.73-1.82 (2H, m), 2.61 (2H, q, J = 7.6Hz ), 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), 7.67-7.73 (4H, m).
LC-MS (LC: Agilent 1200, MS: LCQ Advantage Max): Mobile phase from 5% [water + 0.01% HFBA + 1.0% IPA] and 95% [CH3CN + 0.01% HFBA + 1.0% IPA] to0% [water + 0.01% HFBA + 1.0% IPA] and100% [CH3CN + 0.01% HFBA + 1.0% IPA] in6.0min) .Purityis99.58%, Rt = 2.85min; MSCalcd.: 432.19; MSFound432.2 [M].

The overall reaction schematic diagram of Synthesis Examples 5 and 6 is as follows.

[Synthesis Example 7] Synthesis of Compound DJ-A-5 The procedure of Synthesis Example 3 was repeated in Synthesis Example 1, except that 9-bromo-10- (2 instead of 9-bromo-10-phenylanthracene was synthesized in Synthesis Example 1. -Naphthyl) anthracene was used to synthesize yellow solid DJ-A-5.

1H-NMR (CDCl3, Varian400MHz): δ 1.32-1.42 (12H, m), 1.59-1.65 (2H, m), 1.75-1.81 (2H, m), 2.54 (2H, q, J = 7.6Hz), 2.79 (2H, t, J = 7.6Hz), 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 = 8.4Hz).
LC-MS (LC: Agilent 1200, MS: LCQ Advantage Max): Mobile phase from 0% [water + 0.01% HFBA + 1.0% IPA] and 100% [CH3CN + 0.01% HFBA + 1.0% IPA] to0% [water + 0.01% HFBA + 1.0% IPA] and100% [CH3CN + 0.01% HFBA + 1.0% IPA] in10min) .Purityis99.84%, Rt = 4.95min; MSCalcd.: 552.29; MSFound552.2 [M].

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

[Synthesis Example 8] Synthesis of Compound DJ-A-6 The process of Synthesis Example 7 was repeated except that 1,5-dibromopentane was used instead of 1.10-dibromodecane in Synthesis Example 2, and yellow solid DJ- A-6 was synthesized.

1H-NMR (CDCl3, Varian400MHz): δ1.39 (1H, t, J = 7.2Hz), 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 = 8.4Hz).
LC-MS (LC: Agilent 1200, MS: LCQ Advantage Max): Mobile phase from 0% [water + 0.01% HFBA + 1.0% IPA] and 100% [CH3CN + 0.01% HFBA + 1.0% IPA] to0% [water + 0.01% HFBA + 1.0% IPA] and100% [CH3CN + 0.01% HFBA + 1.0% IPA] in6.0min) .Purityis99.76%, Rt = 2.23min; MSCalcd.: 482.21; MSFound482.2 [M].

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

Synthesis Example 9 CdSe / ZnS Synthesis The CdSe / ZnS synthesis was prepared 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, and nitrogen was added. Heated at 150 ° C. for 30 minutes under atmosphere. Then 20 mL of 1 octadecene (ODE) was added and the temperature was increased to 310 ° C. 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 ° C. for 10 minutes and then cooled to room temperature. The generated quantum dots were purified with 20 mL of chloroform and an excessive amount of acetone (three times or more). The quantum dots were redispersed in chloroform or hexane at a concentration of 5.0 mg / mL.

[Synthesis Example 10] Synthesis of ZnO nanoparticles (nanoparticulars) ZnO nanoparticles were used as an electron transport layer, and the following method was used for ZnO nanoparticle synthesis. That is, 30 mL of dimethyl sulfoxide (DMSO, 0.5M) was added to zinc acetate (Zinc acetate), and a tetramethylammonium hydroxide (TMAH, 0.55M) mixture in ethanol was stirred for 1 hour. Thereafter, it was centrifuged and washed with a mixture of ethanol and excess acetone. The synthesized ZnO nanoparticles were dispersed in ethanol at a concentration of 30 mg / mL and used as an electron transport layer material for an LED manufacturing apparatus.

[Example 1] White light emitting quantum dot synthesis (Ligand Exchange)
White light emitting quantum dots were synthesized by the method shown in FIG. That is, a CdSe / ZnS solution (0.2 ml, 5 mg / ml in hexane) was produced from the quantum dots produced in Synthesis Example 9, and the luminescent material (0.5 ml, 3 mM in hexane) produced in Synthesis Example 3 was used. The mixture was added and stirred at room temperature for 30 minutes. Methanol was added to the reaction flask to solidify it, and then centrifuged to produce white light emitting quantum dots. The results of ligand exchange were confirmed by IR DATA, and UV absorption and PL spectrum were confirmed. FIG. 5 is an FT-IR spectrum of the produced white light-emitting quantum dots, where (a) shows Synthesis Example 3 (DJ-A-1) and (b) shows Example 1 (DJ-A-1 + CdSe / ZnS). ). FIG. 6 shows UV absorption and PL spectra. (A) shows Synthesis Example 8 (QDs), (b) shows Synthesis Example 3, and (c) shows Example 1.

[Example 2] QD-LED device fabrication QD-LEDs were fabricated on a glass (ITO / glass) substrate coated with indium tin oxide (sheet resistance <10Ω / □). The ITO glass was cleaned with acetone and isopropyl alcohol using ultrasonic waves for 1 minute, and then plasma treated with argon / oxygen for 1 minute. Also, poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT: PSS, Baytron P AI 4083) diluted with isopropyl alcohol at a 9: 1 volume ratio, and then spin coated at 4,000 rpm for 30 seconds did. PEDOT: PSS coated ITO glass was baked on the 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 3000 rpm for 30 seconds in a glove box filled with N ₂ , and then the substrate was baked at 180 ° C. for 30 minutes. Used as a hole transport layer. As the light emitting layer, the white light emitting quantum dot solution produced in Example 1 was spin coated at 1,500 rpm for 20 seconds.

Next, a ZnO nanoparticle (30 mg / mL) solution was spin coated at 1500 rpm for 30 seconds and the substrate was baked at 150 ° C. for 30 minutes. Finally, such a multilayer thin film substrate was placed in a high vacuum deposition chamber (background pressure ˜5 × 10 ⁻⁶ torr), and an aluminum cathode (100 nm thickness) was deposited.

[Comparative Example 1] Orange QD-LED device fabrication In Example 2, the orange light emitting quantum dots of Synthesis Example 9 were used as the light emitting layer instead of the white light emitting quantum dots.

[Comparative Example 2] Blue OLED Element Production In Example 2, DJ-A-1 of Synthesis Example 3 was used as a light emitting layer instead of 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 produced above were confirmed. The maximum light emission intensity was 2,000 cd / m 2. The light emission efficiency of each element is shown in Table 1 and Graph 7 below. (A) of FIG. 7 shows Current density and luminance vs. driving voltage, and (b) shows luminance power efficiency vs. luminance.

Further, normalized electroluminescence spectra of the devices manufactured in Example 2 and Comparative Examples 1 and 2 were measured. The results are shown in FIG. 8, (b) is the light source of Comparative Example 1, (c) is the light source of Comparative Example 2, and (d) is the Electroluminescence (EL) spectrum of the LED used as the light source of Example 2, and the half-value width (FWHM). Were 27.8 nm, 39.2 nm, and (42.2 nm, 39.3 nm) in blue, orange and white, respectively.

Claims (10)

A quantum dot comprising a core / shell structure and a ligand attached to the surface of the shell, comprising:
The ligand is
Firing group,
A consolidated group that links the shell and the luminous group;
The core / shell structure and the light emitting group are disposed between the connection group and the light emitting group so that the core / shell structure and the light emitting group of the ligand emit light of a complementary color to each other to emit white light as a whole. A spacer capable of blocking energy transfer between and
The spacer is a substituted or unsubstituted, saturated or unsaturated _C 10 _{-C 30} alkyl _group, cycloalkyl group C 3 _{-C 40,} a silane _Si 1 ~Si _30,
One or more types of the light emitting group are selected from the group consisting of the following groups .











In FL1 to FL6, FL8 to FL14, FL16 to FL38, or PL1 to PL59, * is a connecting part, where the connecting part is connected to one or more of the substitution positions in parentheses, and R1 to R16 are respectively independently hydrogen; deuterium, halogen, amino group, nitrile group, nitro group, _C 2 _~; deuterium, halogen, amino group, nitrile group, alkyl group of _C 1 _{-C 40} substituted or unsubstituted nitro group an aryl group of _C 6 ~C _40;; heterocycloalkyl group of C 3 _{-C 40;} cycloalkyl group C 3 _{-C 40;} alkoxy groups C 1 _{-C 40;} alkenyl groups _{C 40} C 3 ~C ₄₀ an arylthio group or Si der of C 3 _{-C 40;} an aryloxy group _C 3 _{~C 40;} C 3 aralkyl group _{-C 40;} heteroaryl group . Two or more optionally selected from R1 to R16 may be bonded to each other to form a ring, and may include S, N, O, and Si. The core / shell structure emits light in a range of 400 to 500 nm, or emits light in a range of 500 to 800 nm,
When the core / shell structure emits light in the range of 400 to 500 nm, the light emitting group emits light in the range of 500 to 800 nm, and the core / shell structure has 500 to 800 nm. 2. The quantum dot according to claim 1, wherein when emitting light in a region band, the light emitting group emits light in a region band of 400 to 500 nm and emits white light as a whole.   The quantum dot that emits white light according to claim 1, wherein the light emitting group emits light in a band of 400 to 500 nm.   2. The quantum dot emitting white light according to claim 1, wherein the light emitting group emits light having a wavelength range of 500 to 800 nm. The connecting group, thiol (thiol) group, a carboxy group, amine group, phosphine (phospine) groups, and phosphide (phosphide) according to claim 1, characterized in that the at least one selected from the group consisting of group Quantum dots that emit white light. The quantum dot emitting white light according to claim 1 , wherein the ligand is one of those expressed by the following structure:








In the above structure, the H part of -SH is a part bonded to the core / shell structure. The quantum dot emitting white light according to claim 1 , wherein the ligand is one of those expressed by the following structure:





In the above structure, the H part of -SH is a part bonded to the core / shell structure.   The quantum dot emitting white light according to claim 1, wherein the quantum dot has a particle size of 5 to 30 nm.   2. The white light according to claim 1, wherein when the light emission intensity of the core / shell structure is 1, the light emission intensity of the light emission group of the ligand having a complementary color relationship is 0.7-1.3. Quantum dots that emit light. In the light emitting element,
A light emitting device comprising the white light emitting quantum dot according to claim 1 as a light emitting substance.