KR101593582B1 - Quantum dot formed glass composite for color converter, preparation method thereof and white light emitting diode - Google Patents

Abstract

The present invention relates to a color converting glass composite with quantum dots, a preparation method of the same, and a white light emitting diode (LED). More particularly, the present invention relates to a color converting glass composite formed with dispersed quantum dots which are composed of cadmium, sulfur, and selenium in glass. The present invention provides a color converting glass composite with quantum dots, which can utilize advantages of an inorganic color converting material and quantum dots and can embody various colors as well as white light.

Description

TECHNICAL FIELD [0001] The present invention relates to a glass composite for color conversion in which quantum dots are formed, a method of manufacturing the same, and a white light LED device,

The present invention relates to a glass composite for color conversion in which quantum dots are formed, a method for producing the same, and a white light LED element.

LED is a kind of optoelectronic device that emits in the form of light of energy corresponding to the bandgap of semiconductor by the combination of electrons and holes when a voltage is applied. Due to low power consumption, long lifespan and application of eco-friendly materials compared to conventional incandescent lamps, demand for LED light sources has exploded in recent years. Particularly, applications and demands of white light LEDs are greatly increasing in backlight unit (BLU) and automobile lighting of indoor and outdoor lighting, display and portable electronic devices. The implementation of white light LEDs is generally applied by mixing yellow or green and red phosphors on a blue LED diode with an organic binder. As the organic binder, an epoxy or silicone series is mainly used. This method has been widely used in the manufacture of conventional white light LEDs because it is easy to apply the phosphor on the blue LED chip by mixing the phosphor with the organic binder and has high mass productivity and relatively low production cost. However, as the application of white light LEDs has recently expanded, high power white light LEDs such as indoor and outdoor lighting and electric field light are required. Therefore, technologies capable of replacing them have been attracting attention due to inherent limitations of organic binders. When the organic binder is exposed to UV or 150 ° C. for a long time, coloring of the binder to yellow or brown occurs, thereby limiting the practical service life of the LED. In addition, there is a blurring phenomenon in which the fluorescent material of the organic binder moves due to the viscosity of the organic binder and the color of the LED is different depending on the position. When the fluorescent material is not uniformly mixed, binning phenomenon Resulting in lowering the production efficiency.

In order to solve this problem fundamentally, inorganic color conversion material composed of 100% ceramic material was proposed without using organic binder. The inorganic color conversion material is excellent in thermal and chemical durability, so there is no fear of discoloration, and it is advantageous in that it has excellent homogeneity and does not cause blurring and binning problems. Accordingly, there is a need for a technique capable of replacing the conventional organic binder on the basis of the advantages of the inorganic material and the freedom and processability of the glass material using the inorganic color conversion material as described above.

On the other hand, a quantum dot is a semiconductor particle having a size of several nanometers, and the wavelength of light emitted varies depending on the particle size. The light emitted by the quantum dot is generated by electrons coming from the conduction band to the valence band. Fluorescence (light emission) generated at this time generates light of a shorter wavelength as the particles of the quantum dots become smaller, and generates light of a longer wavelength as the particle size increases. Theoretically, it has a quantum efficiency of 100% and can easily be used as a material for color conversion by controlling light emission wavelength through particle size control. However, existing quantum dot materials are chemically synthesized materials. In order to prevent aggregation between quantum dots, a special passivation layer and solution must be used. .

Prior art related to this is a white light LED element using a quantum dot disclosed in Korean Patent Laid-Open No. 10-2009-0064079 (published on Jun. 18, 2009) and a manufacturing method thereof.

Accordingly, the present invention provides a glass composite for color conversion in which quantum dots capable of realizing various colors as well as white light are utilized by exploiting the advantages of the inorganic color conversion material while utilizing the advantages of the quantum dots, a method for manufacturing the same, and a white light LED element have.

The problems to be solved by the present invention are not limited to the above-mentioned problem (s), and another problem (s) not mentioned can be understood by those skilled in the art from the following description.

In order to solve the above problems, the present invention provides a glass composite for color conversion, characterized in that quantum dots composed of cadmium, sulfur and selenium are dispersed and formed in the glass.

The glass may be selected from the group consisting of silicates, borosilicates, alumino-silicates, borates, phosphates, tellurites, oxyflourides, oxynitrides, Oxynitride, and oxysulfide may be used as the organic solvent.

The quantum dots composed of cadmium, sulfur and selenium are characterized by being a single alloy of CdS _{1 -x} Se _x (0 <x <1) or a CdSe / CdS core-cell structure formed with CdS outside CdSe.

The present invention also relates to a glass composite for color conversion in which quantum dots composed of cadmium, sulfur and selenium are dispersed in glass; And a blue LED chip provided below the glass composite for color conversion, wherein light of a blue wavelength generated from the blue LED chip passes through the glass composite for color conversion to emit white light. And a white light LED element.

The present invention also provides a method for preparing a glass composition, comprising: adding a cadmium compound and a zinc compound to a glass composition; And a step of melting and quenching the mixture, annealing the mixture, and heat-treating the mixture, wherein the quantum dots are formed.

The glass composition is characterized by containing 50 to 70 mol% of SiO ₂ , 10 to 30 mol% of Na ₂ O, 1 to 10 mol% of ZnO and 1 to 10 mol% of BaO.

The cadmium compound may be one selected from the group consisting of CdS, CdSe, and CdO.

The cadmium compound is added in an amount of 0.2 to 3 mol% based on the glass composition.

And the zinc compound is ZnS and ZnSe.

The zinc compound is added in an amount of 0.1 to 5 mol% based on the glass composition.

The heat treatment is performed at 450 to 600 ° C for 0.5 to 40 hours.

According to the present invention, quantum dots of CdS _{1- x} Se _x (0 < x < 1) composed of cadmium, sulfur and selenium are formed and dispersed in a glass to prevent discoloration due to excellent thermal and chemical durability, There is no blurring phenomenon in which the LED color is different depending on the position and binning problem in which the color coordinates are changed for each LED.

Unlike the conventional method using a wet chemical process for forming quantum dots, since the quantum dots are formed only by heat treatment, there is an advantage that a passivation layer and a solution for preventing aggregation of particles are not needed, and a thermal and chemically stable inorganic Based quantum dots can be provided, and various colors can be implemented according to the heat treatment temperature and the thickness of the glass for color conversion.

1 is a schematic view showing a white light LED device according to the present invention.
2 is a photograph showing color change of a glass composite for color conversion in which quantum dots are formed according to heat treatment time in Example 1 according to the present invention.
3 is a transmission electron microscope (TEM) photograph of a glass composite for color conversion in which quantum dots are formed according to Example 1 of the present invention.
FIG. 4 is a photograph showing color change of a glass composite in which quantum dots are formed according to heat treatment time in Example 2 according to the present invention. FIG.
5 is a graph showing an absorption spectrum of a glass composite for color conversion in which quantum dots are formed according to heat treatment time in Example 2 according to the present invention.
6 is a transmission electron microscope (TEM) photograph of a glass composite for color conversion in which quantum dots are formed according to Example 2 of the present invention.
7 (a) is a glass composite in which CdSSe quantum dots are formed, (b) is a glass composite in which CdSe quantum dots are formed, and FIG. 7 (c) It is a glass composite in which quantum dots are formed.
8 is a graph showing changes in CIE chromaticity of a glass composite for color conversion in which quantum dots are formed according to Example 3 of the present invention.
9 is a graph showing changes in the emission spectrum of the LED according to the heat treatment time of the glass composite for color conversion in which the quantum dot formed in Example 3 according to the present invention is formed.
10 is a graph showing changes in CIE chromaticity of a glass composite for color conversion in which quantum dots are formed according to Example 2 of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving it will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings.

The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

The present invention provides a glass composite for color conversion, wherein quantum dots composed of cadmium, sulfur and selenium are dispersed in a glass.

The glass composite for color conversion according to the present invention is formed by forming and dispersing quantum dots composed of cadmium, sulfur and selenium in a glass, so that there is no risk of discoloration due to excellent thermal and chemical durability and the homogeneity is excellent, The blurring phenomenon and the binning problem in which the color coordinates are changed for each LED do not occur. Unlike the conventional method using a wet chemical process for forming quantum dots, since the quantum dots are formed only by heat treatment, there is an advantage that a passivation layer and a solution for preventing the aggregation of particles are not needed. Further, the glass composite for color conversion in which the quantum dots are formed according to the present invention can provide thermally and chemically stable inorganic-based quantum dots, and various colors can be realized according to the heat treatment temperature and the thickness of the glass for color conversion.

In the glass composite for color conversion according to the present invention, the glass may be a silicate, a boro-silicate, an alumino-silicate, a borate, a phosphate, a tellurite tellurite, oxyfluoride, oxynitride, and oxysulfide may be used as the metal oxide.

The quantum dot may be a single alloy of CdS _{1 -x} Se _x (0 <x <1) or a CdSe / CdS core-cell structure having CdS formed outside CdSe, and the quantum dot preferably has a size of 2 to 8 nm . When the size of the quantum dots is less than 2 nm, there is a problem that the emission wavelength is shorter than visible light. When the size exceeds 8 nm, there is a problem that the emission wavelength is in the near-infrared region longer than visible light.

The present invention also relates to a glass composite for color conversion in which quantum dots composed of cadmium, sulfur and selenium are dispersed in glass; And

And a blue LED chip provided under the glass for color conversion,

And blue light emitted from the blue LED chip passes through the color conversion glass to emit white light.

The white light LED device according to the present invention includes a glass composite for color conversion formed by dispersing quantum dots and a blue LED chip, and the blue wavelength light generated from the blue LED chip passes through the glass composite for color conversion, It can emit light.

1 is a schematic view showing a white light LED device according to the present invention. Referring to FIG. 1, a white light LED device 100 according to the present invention includes a glass composite body 110 for color conversion in which quantum dots are dispersed on a blue LED chip 120.

The present invention also provides a method for preparing a glass composition, comprising: adding a cadmium compound and a zinc compound to a glass composition; And

And melting and quenching the mixture, annealing the mixture, and heat-treating the mixture, wherein the quantum dots are formed.

The method for producing a glass composite for color conversion in which quantum dots are formed according to the present invention includes a step of adding a cadmium compound and a zinc compound to a glass composition and then mixing.

At this time, the glass composition includes 50 to 70 mol% of SiO ₂ , 10 to 30 mol% of Na ₂ O, 1 to 10 mol% of ZnO and 1 to 10 mol% of BaO.

When the SiO ₂ content is less than 50 mol%, the glass crystal is unstable, the structure becomes rough and the thermal expansion coefficient increases, and when the SiO _{2 content} is more than 70 mol% There is a problem that melting and molding of the glass becomes difficult.

In addition, Na ₂ O has an effect of lowering the melting temperature of the glass. By including Na ₂ O in an amount of 10 to 30 mol%, increase in the glass transition temperature can be suppressed and vitrification can be easily carried out.

In addition, ZnO is a component that reduces the glass transition temperature and decreases the glass transition point, and is contained in an amount of 1 to 10 mol%, thereby preventing the glass from being dispersed or degraded in resistance to devitrification. BaO improves the melting property of the glass And serves to lower the roughness of the glass crystal to be precipitated, and is contained in an amount of 1 to 10 mol%, thereby preventing the same problem as ZnO.

The above-described glass composition may additionally contain other additives, so that the composition and the content of the materials constituting the glass composition may vary, and thus the present invention is not limited thereto.

The cadmium compound is preferably added in an amount of 0.2 to 3 mol% based on the glass composition. The cadmium compound may be one selected from the group consisting of CdSe, CdS, and CdO. When the cadmium compound is added in an amount of less than 0.2 mol%, quantum dots are not formed. When the amount of the cadmium compound is more than 3 mol%, the formation of quantum dots can not be controlled through heat treatment.

The zinc compound is ZnS and ZnSe. When the zinc compound is added only to ZnS, the color conversion is not performed and the color conversion efficiency is low.

The zinc compound is preferably added in an amount of 0.1 to 5 mol% based on the glass composition. Specifically, ZnS and ZnSe are preferably added in an amount of 0.1 to 2 mol% and ZnSe in an amount of 0.1 to 2 mol%, respectively. When ZnS and ZnSe are added in an amount of less than 0.1 mol%, quantum dots are not formed. The size of the quantum dots can not be controlled and a desired color can not be realized.

Next, a method for producing a glass composite for color conversion in which quantum dots are formed according to the present invention includes a step of melting, quenching and annealing the mixture, followed by heat treatment.

In the method for producing a glass composite for color conversion in which quantum dots are formed according to the present invention, the melting is preferably performed at 1300 to 1500 ° C. When the melting is performed at a temperature lower than 1300 ° C, the glass composition is not melted and a glass composite is not produced. When the melting temperature is higher than 1500 ° C, the glass composition is easily volatilized and composition control is difficult.

The quenching process may be performed by pouring a glass melt onto a metal or a carbon plate, and may be performed using air or gas, and may be performed using a liquid such as water, liquid nitrogen, or the like. . &Lt; / RTI &gt;

The annealing is preferably performed at a temperature in the vicinity of the glass transition temperature or 300 to 400 ° C. When the annealing is performed at a temperature of less than 300 ° C, there is a problem that the thermal stress generated during the production of the glass is lowered, and when the temperature exceeds 400 ° C, the control of the quantum dots is difficult.

The heat treatment is preferably performed at 450 to 600 ° C for 0.5 to 40 hours. When the heat treatment temperature is lower than 450 캜, there is a problem that quantum dots are not formed. When the heat treatment temperature is higher than 600 캜, there is a problem that size control due to excessive quantum dot growth is difficult. Further, the heat treatment time is the same as the reason for limiting the above-mentioned heat treatment temperature.

Example 1: Production of quantum dot glass composite for quantum dots with color conversion 1

1 mol% CdO, 0.25 mol% ZnS and 0.25 mol% ZnSe were added to a glass composition of 65 mol% SiO ₂ , 25 mol% Na ₂ O, 5 mol% ZnO and 5 mol% BaO . The mixture was melted at 1400 占 폚 for 1 hour, annealed at 350 占 폚 for 1 hour, and then heat-treated at 520 占 폚 to prepare quantum dot-forming glass composites for color conversion.

FIG. 2 is a photograph showing a glass composite for color conversion in which quantum dots are formed according to the heat treatment time according to Example 1 of the present invention. FIG. 2 is a glass composite in a bulk state, and the lower picture is a glass composite polished in a thickness of 1 mm. As shown in FIG. 2, the glass before the heat treatment is transparent, but it is confirmed that the color is generated as the heat treatment time is increased.

3 is a transmission electron microscope (TEM) photograph of a glass composite for color conversion in which quantum dots are formed according to Example 1 of the present invention. As shown in FIG. 3, it can be seen that single alloy quantum dots CdS _{1 -x} Se _x (0 < x < 1) are dispersed in the glass.

Example 2: Production of glass composite for quantum dots with color conversion 2

0.5 mol% CdO, 1 mol% ZnS and 0.5 mol% ZnSe were added to a glass composition of 65 mol% SiO ₂ , 25 mol% Na ₂ O, 5 mol% ZnO and 5 mol% , A glass composite for color conversion in which quantum dots were formed was prepared in the same manner as in Example 1 above.

4 is a photograph showing a glass composite in which quantum dots are formed according to heat treatment time in Example 2 according to the present invention. As shown in FIG. 4, as the heat treatment time is gradually increased, it changes from green to red.

5 is a graph showing an absorption spectrum of a glass composite for color conversion in which quantum dots are formed according to heat treatment time in Example 2 according to the present invention. As shown in FIG. 5, as the annealing time is increased, the absorption spectrum changes according to the change of the quantum dot size.

6 is a transmission electron microscope (TEM) photograph of a glass composite for color conversion in which quantum dots are formed according to Example 2 of the present invention. As shown in FIG. 6, it can be seen that quantum dots of CdS _{1 -x} Se _x (0 <x <1) are dispersed in the glass, and CdS _{1 -x} Se _x (0 <x <1) Cell structure in which CdS is formed.

Example 3: White light LED element

Consisting of cadmium, sulfur and selenium in glass _{CdS 1 -x Se x (0 <} x <1) of Example 1 to glass complex for 2 color conversion of the color conversion and the blue glass complex for the lower quantum dot formed by the dispersion of the A white light LED device was fabricated with an LED chip.

Experimental Example: Analysis of Peak Change and CIE Chromaticity according to Composition and Heat Treatment Time of Glass Composite for Color Conversion with Quantum Dots

The composition of the cadmium oxide and the zinc compound added in the glass composite for color conversion with the quantum dots according to the present invention and the change in the peak and CIE chromaticity according to the heat treatment time were analyzed and the results are shown in FIGS. 7, 8, 9 10.

7 (a) is a glass composite in which CdSSe quantum dots are formed, and FIG. 7 (b) is a graph showing a change in absorption peak of a glass having a CdSe quantum dot formed thereon (C) is a glass composite in which quantum dots of CdS are formed. As shown in FIG. 7, the glass composite in which the quantum dot of CdSSe is formed in the glass composite shows a peak at a wavelength of 600 nm due to color conversion. On the other hand, CdSe and CdS are not suitable for realizing color conversion because there is little or no emission spectrum due to color conversion in addition to the peak at 450 nm due to LED.

8 is a graph showing changes in CIE chromaticity of a glass composite for color conversion in which quantum dots are formed according to Example 3 of the present invention. As shown in FIG. 8, the glass composite for color conversion according to the present invention can realize white light because quantum dots of CdSSe are formed and color coordination appears near the white region, and the color conversion efficiency (conversion efficiency is greatly improved.

9 is a graph showing changes in the emission spectrum of the LED according to the heat treatment time of the glass composite for color conversion in which the quantum dot formed in Example 3 according to the present invention is formed. The heat treatment was performed at 500 캜. As shown in FIG. 9, the glass composite in which the quantum dot of CdSSe was formed in the glass composite peaks at a wavelength of about 500 nm when the heat treatment is performed for 5 hours, and the heat treatment time increases to 10 hours, 15 hours, and 20 hours The peak shifted from about 540 nm to about 580 nm. Accordingly, various colors can be realized by changing the color of the glass composite by adjusting the heat treatment time, and LED color can be adjusted by providing the LED chip.

10 is a graph showing the CIE chromaticity change of the glass composite for color conversion with the quantum dot formed in Example 2 according to the present invention. The thickness of the glass composite was varied from 1.3 mm to 1.1 mm for each annealing time. As shown in FIG. 10, it can be seen that the glass composite for color conversion according to the present invention can realize various LED colors according to the heat treatment time and thickness control. In Fig. 10, the red dot (x, y) is (0.3277, 0.3458). As shown in FIG. 10, the glass composite for color conversion according to the present invention can realize various colors according to the heat treatment time, and the white light can be realized by adjusting the heat treatment time and the thickness of the glass composite for color conversion Able to know.

Although a glass composite for color conversion in which quantum dots are formed according to the present invention, a method of manufacturing the same, and a specific embodiment of the white light LED device have been described, various modifications may be made without departing from the scope of the present invention. Do.

Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be determined by the scope of the appended claims and equivalents thereof.

It is to be understood that the foregoing embodiments are illustrative and not restrictive in all respects and that the scope of the present invention is indicated by the appended claims rather than the foregoing description, It is intended that all changes and modifications derived from the equivalent concept be included within the scope of the present invention.

100: white light LED element
110: Glass composite for color conversion in which quantum dots are formed
120: Blue LED chip

Claims (12)

Wherein quantum dots composed of cadmium, sulfur and selenium are dispersed in the glass,
The quantum dots include CdS _1-x Se _x (0 < x < 1) by melting and quenching a glass composition containing 0.2 to 3 mol% of CdO and 0.1 to 5 mol% of ZnS and ZnSe, ) Or a CdSe / CdS core-cell structure in which CdS is formed outside of CdSe.
The method according to claim 1,
The glass may be selected from the group consisting of silicates, borosilicates, alumino-silicates, borates, phosphates, tellurites, oxyflourides, oxynitrides, Oxynitride, and oxysulfide. The glass composite for color conversion according to claim 1,
delete The method according to claim 1,
Wherein the quantum dot comprising cadmium, sulfur and selenium has a size of 2 to 8 nm.
A glass composite for color conversion in which quantum dots composed of cadmium, sulfur and selenium are dispersed in glass; And
And a blue LED chip provided under the glass composite for color conversion,
Wherein light of a blue wavelength generated from the blue LED chip passes through the glass composite for color conversion to emit white light,
The quantum dots include CdS _1-x Se _x (0 < x < 1) by melting and quenching a glass composition containing 0.2 to 3 mol% of CdO and 0.1 to 5 mol% of ZnS and ZnSe, ) Or a CdSe / CdS core-cell structure in which CdS is formed outside CdSe.
Adding 0.2 to 3 mol% of CdO to the glass composition, adding 0.1 to 5 mol% of ZnS and ZnSe, and then mixing; And
And melting and quenching the mixture, annealing the mixture, and heat-treating the mixture, wherein the quantum dots are formed.
The method according to claim 6,
Wherein the glass composition comprises 50 to 70 mol% of SiO ₂ , 10 to 30 mol% of Na ₂ O, 1 to 10 mol% of ZnO and 1 to 10 mol% of BaO. Gt;
delete delete delete delete The method according to claim 6,
Wherein the heat treatment is performed at 400 to 600 ° C for 0.5 to 40 hours.

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