JP6708967B2 - Quantum dot phosphor and light emitting device using the same - Google Patents

Description

The present invention relates to a quantum dot phosphor and a light emitting device using the same.

Fluorescent lamps, which are widely used as a light source, have drawbacks such as the use of mercury, which is a harmful substance, and the short life. For this reason, in recent years, a light emitting diode (LED: Light Emitting Diode) has been used as a light source.

A light emitting element configured by using an LED as a light source (hereinafter, also referred to as an LED light emitting element) does not use a harmful substance, has a long life, has high emission efficiency, and the like. It has the following advantages.

(I) Since the LED light emitting element can be driven by direct current, it does not cause the flicker that occurs in conventional fluorescent lamps driven by alternating current and is easy on the eyes.
(Ii) Since the LED light emitting element generates a smaller amount of ultraviolet rays (UV: Ultra Violet ray) than a conventional fluorescent lamp, the LED light emitting element has less influence on the human body and can further suppress material deterioration.
(Iii) Since the LED light emitting element does not use glass used in conventional fluorescent lamps, it has high safety and good operability.

The LED light-emitting element having such characteristics has attracted attention as a next-generation light source for lighting such as home lighting and for a backlight of a liquid crystal display element, and has been actively researched and developed in recent years.

The following three methods are known as methods for obtaining white light using an LED light emitting element.

(1) White light obtained by combining three types of LEDs having emission wavelengths (peak wavelengths of emission) of red (R: Red), green (G: Green) and blue (B: Blue), which are the three primary colors of light. Method to get.
(2) Using a blue LED having a blue emission wavelength and a phosphor having an emission wavelength of yellow, green, red, etc. that uses blue emission as excitation light, the blue emission from the excitation source and the emission from the phosphor are used. A method of obtaining white light by mixing with the emission of yellow, green, red, etc. In this system, a phosphor having an emission wavelength of yellow, green, red, or the like serves as a wavelength conversion phosphor material, and wavelength-converts blue emission from a blue LED into emission of yellow, green, red, or the like.
(3) Phosphors that use light in the near-ultraviolet region with a wavelength shorter than 380 nm, that is, UV-LEDs having an emission wavelength of UV, and phosphors having emission wavelengths of red, green, and blue that use UV as excitation light, A method of obtaining white light by mixing the red, green, and blue light emitted from. In this system, a phosphor having emission wavelengths of red, green, and blue converts wavelengths of UV from a UV-LED into red, green, and blue emission as a wavelength conversion phosphor material.

FIG. 1 shows an example of the structure of a light emitting device having the LED light emitting element of the above (2) system.

In the light emitting device of FIG. 1, the blue LED chip 1 is connected to the lead frame 3 by the wire 2. The blue LED chip 1 is adhered to the heat sink 6. In addition, the blue LED chip 1 is housed in the case 4 by the transparent resin 5 in which the phosphor particles 7 having the emission wavelengths of yellow, green, red, etc., which emit blue light from the blue LED chip 1 as excitation light, are encapsulated. It is sealed.

When power is supplied to the lead frame 3 from the external drive circuit, the blue LED chip 1 is turned on and emits blue light. The heat sink 6 has a role of releasing heat generated from the blue LED chip 1 at the time of light emission to the outside, suppresses an increase in temperature of the blue LED chip 1, and stabilizes light emission. Part of the blue light emitted from the blue LED chip 1 emits blue light as it is, and the rest of the blue light emission excites the phosphor particles 7 in the transparent resin 5. The excited phosphor particles 7 emit yellow, green, red and the like. The blue light emission from the blue LED chip 1 and the light emission of each color from the phosphor particles 7 are mixed to obtain white light. This structure is mainly used in a light emitting device for a lighting fixture.

FIG. 2 shows an example of a light emitting device having an LED light emitting element of the above method (2) different from the structure of the light emitting device of FIG. The light emitting device shown in FIG. 2 has a structure capable of irradiating the light emitted from the LED light emitting element on a wide surface by the light guide 9 and the reflection sheet 8.

In the light emitting device of FIG. 2, the blue LED chip 1 is sealed with the transparent resin 5, but the phosphor particles 7 are not sealed in the transparent resin 5. The phosphor particles 7 are enclosed in a transparent resin 5A, and the light guide 9 has a structure sandwiched between the transparent resin 5A and a reflection sheet 8. The phosphor particles 7 are made of a phosphor that emits blue light from the blue LED chip 1 as excitation light and has emission wavelengths such as yellow, green, and red.

The blue light emitted from the blue LED chip 1 spreads while being guided through the light guide 9 or while being guided through the light guide 9 and reflected by the reflection sheet 8. Transmits as blue light as it is. The rest of the blue light emission is used as excitation light for the phosphor particles 7, and is converted by the phosphor particles 7 into light emission of yellow, green, red, or the like. The blue light emission from the blue LED chip 1 and the light emission of each color from the phosphor particles 7 are mixed to obtain white light. This structure is mainly used in a backlight for a liquid crystal display as well as a light emitting device for a lighting fixture.

In a liquid crystal display that uses light emitted from a light emitting device having an LED light emitting element of the above method (2) as backlight light, colors corresponding to each pixel (blue, red, green) pass the backlight light through a color filter. It is realized by

The conventional phosphor particles used in the light-emitting device as described _{above, YAG: Ce (Y 3 Al} 5 O 12: Ce) _{other, Tb 3 Al 5 O 12:} Ce, Lu 3 Al 5 O 12: Ce, Ca(Si,Al) ₁₂ (O,N) ₁₆ :Eu, (Si,Al) ₆ (O,N) ₈ :Eu, CaAlSiN ₃ :Eu, CaS:Eu, SrS:Eu, ZnS:Cu, _{al, SrGa 2 S 4: Eu} , CaGa 2 S 4: Eu, (Sr, Ca, Ba) SiO 4: Eu, (Sr, Ca, Ba) 3 SiO 5: Eu, CaSc 2 O 4: Ce, Ca 3 _{sc 2 Si 3 O 12: Ce} , Ca 8 MgSi 4 O 16 Cl 2: Eu, SrAl 2 O 4: Eu and the like, which has a particle size of about several Myuemu～10myuemu. Further, each of these phosphor particles has a unique emission wavelength.

FIG. 3A shows an emission spectrum of backlight light using conventional phosphor particles, and FIG. 3B shows the transmittance of color filters for each color (blue, green, and red) [solid line indicates blue color filter]. Transmittance (peak of transmittance: about 450 nm), dashed line indicates transmittance of green color filter (peak of transmittance: about 490 nm), dotted line indicates transmittance of red color filter (peak of transmittance: about 650 nm) ], (c) shows the spectrum of each color (blue, green, red) of the liquid crystal display obtained from the emission spectrum of (a) and the transmittance of (b). As shown in FIG. 3A, the peak widths of the emission wavelengths of green and red of about 500 nm to about 750 nm, which correspond to the emission spectrum of the phosphor particles in the emission spectrum of the backlight light, are wide, The peak widths of the green and red emission wavelengths after passing through the color filter (FIG. 3B) are also widened (FIG. 3C). Therefore, when the conventional phosphor particles are used, the transmittance of the color filter cannot be increased, and as a result, the luminous efficiency is deteriorated. Further, since the emission wavelength peak width of the emission spectrum is wide, the color purity is poor.

In contrast to such conventional phosphor particles, in recent years, phosphor particles having a particle size of several nm to 10 nm, that is, a so-called quantum dot phosphor has attracted attention. The quantum dot phosphor has a semiconductor composition.

FIG. 4A shows the emission spectrum of the backlight light using the quantum dot phosphor, and FIG. 4B shows the transmittance of the color filters for each color (blue, green, red) (FIG. 3B). The same) and (c) show spectra of each color (blue, green, red) of the liquid crystal display obtained from the spectrum of (a) and the transmittance of (b). As shown in FIG. 4A, the peak widths of the emission wavelengths of green and red of about 500 nm to 750 nm, which correspond to the emission spectrum from the quantum dot phosphor in the emission spectrum of the backlight, are narrow, The peak width of each emission wavelength of green and red after passing through the color filter (FIG. 4B) is also narrow (FIG. 4C), and the color purity of each color is good. From this, when the quantum dot phosphor is used, the transmittance of the color filter can be increased more than when the conventional phosphor particles are used, and as a result, the luminous efficiency can be improved. Furthermore, since the color purity of each color is good, the color reproduction range of the liquid crystal display can be expanded.

Further, the quantum dot phosphor has a feature that the emission wavelength can be changed by changing the particle size.

Examples of quantum dot phosphors include CdSe/ZnS (core/shell) quantum dot phosphors, InP/ZnS quantum dot phosphors, and CuInS ₂ /ZnS quantum dot phosphors. In the CdSe/ZnS quantum dot phosphor, by covering the surface of CdSe (core) whose emission efficiency is low due to defects on the crystal surface with ZnS (shell), the defects on the crystal surface are repaired and the emission efficiency is improved.

However, the CdSe/ZnS quantum dot phosphor contains harmful Cd whose use amount is limited by the RoHS regulation. In addition, InP/ZnS quantum dot phosphors and CuInS ₂ /ZnS quantum dot phosphors, which are known as Cd-free quantum dot phosphors, have a problem that their luminous efficiency is lower than that of CdSe/ZnS quantum dot phosphors. is there.

Further, Patent Documents 1 and 2 describe a method in which a quantum dot phosphor is adopted in the structure of FIG. 1, but in the light emitting device shown in FIG. 1, a wide surface is uniformly irradiated with white light. It's difficult.

JP, 2007-103511, A JP, 2007-103513, A

In view of the above conventional situation, it is an object of the present invention to provide a quantum dot phosphor that has high luminous efficiency and does not contain harmful substances such as Cd, and a light emitting device using the quantum dot phosphor.

As a result of intensive studies, the present inventors have made it possible to reduce non-emission transitions due to crystal defects in CuInS ₂ quantum dot phosphors or CuInS ₂ /ZnS quantum dot phosphors, which are quantum dot phosphors. It has been found that the above problems can be solved by substituting the In site in the CuInS ₂ quantum dot phosphor or the CuInS ₂ /ZnS quantum dot phosphor with an Al element and/or a Ga element that is a homologous element to the In element, and completed the present invention. did.

That is, the quantum dot phosphor according to the present _{invention, Cu (In 1-x-} y Al x Ga y) S 2 (0 <x + y ≦ 0.4,0 ≦ x ≦ 0.4,0 ≦ y ≦ 0. 4) _or that represented by _{Cu (in 1-x-y} Al x Ga y) S 2 /ZnS(0<x+y≦0.4,0≦x≦0.4,0≦y≦0.4) Is characterized by.

The present invention provides a quantum dot phosphor having high luminous efficiency and containing no harmful substances such as Cd, and further provides a light emitting device having improved luminous efficiency by using the quantum dot phosphor of the present invention. ..

Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

It is a figure which shows an example of a structure of the light-emitting device which has an LED light-emitting element. It is a figure which shows an example of a structure of the light-emitting device which has an LED light-emitting element. It is a figure which shows the light emission spectrum of the liquid crystal display using the conventional fluorescent substance particle. It is a figure which shows the light emission spectrum of the liquid crystal display using a quantum dot fluorescent substance. It is the figure which represented typically an example of the fluorescent substance film which enclosed the quantum dot fluorescent substance of this invention in the transparent resin. It is the figure which represented typically an example of the light-emitting device manufactured using the fluorescent substance film containing the quantum dot fluorescent substance of this invention. It is the figure which represented typically an example of the light-emitting device manufactured using the fluorescent substance film containing the quantum dot fluorescent substance of this invention. It is the figure which represented typically an example of the liquid crystal display panel manufactured using the light emitting device which has the quantum dot fluorescent substance of this invention as a backlight. In CuInS ₂ / ZnS-based quantum dot phosphor is a diagram showing a relationship between emission wavelength for the particle diameter. It is a diagram showing the relationship between quantum efficiency (relative value) with respect to _{Cu (In 1-x Al x} ) Al in _{S 2} quantum dot phosphor concentration (x). Is a diagram showing the relationship between quantum efficiency (relative value) with respect to the excitation wavelength in _{Cu (In 0.7 Al 0.3) S} 2 quantum dot phosphors. Is a diagram showing the relationship between quantum efficiency (relative value) with respect to _{Cu (In 1-x Al x} ) Al in S 2 / ZnS quantum dot phosphor concentration (x). Is a diagram showing the relationship between quantum efficiency (relative value) with respect to the excitation wavelength in _{Cu (In 0.7 Al 0.3) S} 2 / ZnS quantum dot phosphor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like. In the drawings, the size and shape of each part are exaggerated for clarity, and the actual size and shape are not accurately drawn. Therefore, the technical scope of the present invention is not limited to the size and shape of each part shown in these drawings. Furthermore, the following description shows specific examples of the content of the present invention, and the present invention is not limited to these descriptions, and those skilled in the art within the scope of the technical idea disclosed in the present specification. Various changes and modifications can be made. Further, in the drawings for explaining the present invention, components having the same function are denoted by the same reference numeral, and repeated description thereof may be omitted.

<Quantum dot phosphor>
The quantum dot phosphor of the present invention has a crystal structure of CuInS ₂ quantum dot phosphor or CuInS ₂ /ZnS quantum dot phosphor, and a part of the In site is an Al element and/or Ga that is a homologous element to the In element. The following structures replaced by elements:
_{Cu (In 1-x-y} Al x Ga y) S 2 (0 <x + y ≦ 0.4,0 ≦ x ≦ 0.4,0 ≦ y ≦ 0.4)
Or
_{Cu (In 1-x-y} Al x Ga y) S 2 /ZnS(0<x+y≦0.4,0≦x≦0.4,0≦y≦0.4)
Have.

Here, the range of _Cu of the present invention in the _{(In 1-x-y Al} x Ga y) S 2 quantum dot phosphor (also referred to as "x + y" herein) Al concentration (x) + Ga concentration (y) Is 0<x+y≦0.4, preferably 0.1≦x+y≦0.3, more preferably 0.1≦x+y≦0.2, and the range of x is 0≦x≦ 0.4, preferably 0≦x≦0.3, more preferably 0≦x≦0.2, and the range of y is 0≦y≦0.4, preferably 0≦ y≦0.3, and more preferably 0≦y≦0.2.

The _{Cu (In 1-x-y} Al x Ga y) S 2 / ZnS quantum dot phosphor of the present invention, the range of Al concentration (x) + Ga concentration (y) is 0 <x + y ≦ 0.4, Preferably 0.1≦x+y≦0.4, more preferably 0.2≦x+y≦0.4, especially 0.3≦x+y≦0.4, and the range of x is 0≦x ≦0.4, preferably 0≦x≦0.3, more preferably 0≦x≦0.2, and the range of y is 0≦y≦0.4, preferably 0. ≦y≦0.3, and more preferably 0≦y≦0.2.

_Cu of the present invention _{(In 1-x-y Al} x Ga y) S 2 quantum dot phosphors and _{Cu (In 1-x-y} Al x Ga y) in S 2 / ZnS quantum dot phosphor, Al concentration (x ), Ga concentration (y) and x+y within the above ranges, higher luminous efficiency can be obtained than the CuInS ₂ quantum dot phosphor and the CuInS ₂ /ZnS quantum dot phosphor that do not contain Al and Ga.

The emission wavelength of the quantum dot phosphor of the present invention can be changed by changing its particle size. Therefore, the quantum dot phosphor of the present invention can change the particle size according to the emission of the color desired by a person skilled in the art, and is not limited to the following, but when measured by a transmission electron microscope observation image, Cu( in _{in 1-x-y Al x} Ga y) S 2 quantum dot phosphors, usually 1 nm to 10 nm, the average particle size preferably 2.0Nm～6.0Nm, more preferably between 2.5nm~5.5nm (median diameter: d50) _has, in the _{Cu (in 1-x-y} Al x Ga y) S 2 / ZnS quantum dot phosphor, usually 1 nm to 10 nm, preferably 3.0Nm～7.0Nm, more preferably Has an average particle diameter (median diameter: d50) between 3.5 nm and 6.5 nm. The particle size is measured by a transmission electron microscope observation image as follows. First, 100 particles are randomly selected, and the minor axis and major axis of each particle are measured. Subsequently, the average value of the short diameter and the long diameter of each particle is calculated and used as the diameter of each particle. Finally, the diameter of each particle is averaged, and the obtained value is used as the particle diameter of the quantum dot phosphor.

The quantum dot phosphor of the present invention preferably has a uniform particle size, for example, a sharp peak of frequency distribution in the particle size distribution.

_Cu of the present invention _{(In 1-x-y Al} x Ga y) S 2 quantum dot phosphors and _{Cu (In 1-x-y} Al x Ga y) the above-mentioned range the particle size of the S 2 / ZnS quantum dot phosphor The quantum dot phosphor has an emission wavelength in the visible light wavelength range, and the particle diameters are uniform, whereby the color purity of each color emitted from the quantum dot phosphor is improved.

The quantum dot phosphor of the present invention may vary depending on the particle size, but usually has an emission wavelength between 500 nm and 800 nm. For example, a quantum dot phosphor having a green emission wavelength usually has an emission wavelength of 500 nm to 600 nm, preferably 520 nm to 560 nm, more preferably 530 nm to 550 nm, and has, for example, a red emission wavelength. The quantum dot phosphor usually has an emission wavelength of 600 nm to 750 nm, preferably 600 nm to 640 nm, and more preferably 610 nm to 630 nm.

In the present specification, “having a light emission wavelength (between) of (phrase indicating color or wavelength)” means that the phosphor (or light emitting element) is excited by absorbing excitation light, It is meant to have the property of emitting light of the indicated color or to have the property of emitting light having a peak wavelength of emission between the wavelengths shown therein. For example, “a phosphor having a green emission wavelength” refers to a phosphor having a property of being excited by absorbing excitation light to emit green light, and “fluorescence having an emission wavelength of 500 nm to 600 nm”. The "body" refers to a phosphor having a property of being excited by excitation light to emit light having a peak wavelength of emission between 500 nm and 600 nm.

Regarding the relationship between the particle size and the emission wavelength in the quantum dot phosphor of the present invention, the emission wavelength becomes longer as the particle size becomes larger. For _example, in the _{Cu (In 1-x-y} Al x Ga y) S 2 quantum dot phosphor, the particle diameter of the quantum dot phosphor becomes to 3.0Nm～3.6Nm, quantum dot phosphors of 530nm~560nm When the quantum dot phosphor has an emission wavelength between 4.2 nm and 4.5 nm, the quantum dot phosphor has an emission wavelength between 590 nm and 620 nm, and the quantum dot phosphor has a particle diameter. When There will 4.5Nm～4.8Nm, quantum dot phosphor has an emission wavelength between _{620Nm～650nm,} the _{Cu (in 1-x-y} Al x Ga y) S 2 / ZnS quantum dot phosphor , When the particle size of the quantum dot phosphor is 4.0 nm to 4.6 nm, the quantum dot phosphor has an emission wavelength between 530 nm and 560 nm, and the particle size of the quantum dot phosphor is 5.2 nm to 5. At 5 nm, the quantum dot phosphor has an emission wavelength between 590 nm and 620 nm, and when the quantum dot phosphor has a particle size of 5.5 nm to 5.8 nm, the quantum dot phosphor has between 620 nm and 650 nm. Has an emission wavelength.

The excitation light used to emit the quantum dot phosphor of the present invention is not limited as long as it is light that has a wavelength shorter than the emission wavelength of the quantum dot phosphor and can be absorbed by the quantum dot phosphor, and is usually It is possible to use light having an emission peak wavelength in the range of 300 nm to 500 nm, preferably 340 nm to 450 nm, more preferably 350 nm to 450 nm, and particularly 380 nm to 450 nm. In _particular, in the _{Cu (In 1-x-y} Al x Ga y) S 2 quantum dot phosphors, preferably 360 to 450 nm, more preferably be used a light having a peak wavelength of emission between 380nm~450nm in the _{Cu (in 1-x-y} Al x Ga y) S 2 / ZnS quantum dot phosphor, preferably 340Nm～450nm, more preferable to use a light having a peak wavelength of emission between 350nm~450nm it can. As an excitation source used for emitting the quantum dot phosphor of the present invention, it is preferable to use a blue LED having an emission wavelength of usually 380 nm to 450 nm, preferably 400 nm to 450 nm, more preferably 440 nm to 450 nm.

By using light having an emission peak wavelength within the above range as the excitation light used to emit the quantum dot phosphor of the present invention, the excitation light of the present invention can be used as compared with the case of using excitation light of less than 300 nm. High luminous efficiency can be obtained in the quantum dot phosphor. Further, since a blue LED can be used as an excitation source used to emit the quantum dot phosphor of the present invention, by using the quantum dot phosphor of the present invention in the light emitting device of the method (2), A highly efficient light emitting device can be obtained.

The present quantum dot phosphor can be synthesized by a conventionally known method, for example, but not limited to, a solvothermal method which is a liquid phase synthesis method.

_Hereinafter, an example of a _{Cu (In 1-x-y} Al x Ga y) S 2 quantum dot phosphors and _{Cu (In 1-x-y} Al x Ga y) Synthesis of S 2 / ZnS quantum dot phosphor Show.

_{(I) Cu} as a synthetic raw material of _{(In 1-x-y Al} x Ga y) S 2 quantum dot phosphors, as Cu source, a copper halide, for example iodide (I) (CuI) or copper acetate ( I) (Cu(CH ₃ COO)) and the like, and examples of the In source include indium organic acid such as indium triacetate (In(CH ₃ COO) ₃ ) and indium chloride (InCl ₃ ). As the Al source, there may be mentioned organic acid aluminum such as aluminum triacetate (Al(CH ₃ COO) ₃ ), aluminum chloride (AlCl ₃ ), etc., and as the Ga source, organic acid gallium such as gallium triacetate ( Ga(CH ₃ COO) ₃ ), gallium chloride (GaCl ₃ ), and the like can be given. As the S source, organic sulfur compounds, for example, thiols such as dodecanethiol (CH ₃ (CH ₂ ) ₁₁ SH), sulfur powder ( S) etc. can be mentioned. As a raw material, it is preferable to use copper iodide, indium triacetate, aluminum triacetate, gallium triacetate, or dodecanethiol.

The amount of each raw _{material, Cu:} the molar ratio of _{(In 1-x-y Al} x Ga y) is 1: becomes 1, an In: Al: molar ratio of Ga 1-x-y: x: becomes y , Al concentration (x), Ga concentration (y) and x+y are adjusted within the above range. The amount of the raw material of the S source is adjusted to be 2 mol or more with respect to 1 mol of Cu.

The solvent is not limited as long as it can be used by the solvothermal method, and examples thereof include dodecanethiol and octadecene. As the solvent, it is preferable to use dodecanethiol, which can also be used as the S source. The amount of solvent is adjusted so that the total amount of all raw materials is usually 90% by weight to 99% by weight, preferably 98% by weight to 99% by weight, based on the total weight of the reaction solution. When a compound that can be used as the S source is used as the solvent, the amount of the solvent is usually 85% by weight based on the total weight of the reaction solution (including the amount of the compound used as the S source). % To 99% by weight, preferably 95 to 99% by weight.

The synthesis temperature and the synthesis time may be different depending on the particle size of the quantum dot phosphor to be synthesized, and are not limited, but the synthesis temperature is usually adjusted at a temperature between 160° C. and 200° C. Is usually adjusted for a time between 3 and 12 hours.

The particle size can be increased by increasing the synthesis temperature and prolonging the synthesis time, and the particle size can be reduced by lowering the synthesis temperature and shortening the synthesis time.

The synthesis atmosphere is usually an atmosphere in which oxygen is blocked, and is, for example, an inert gas atmosphere such as nitrogen or argon.

_{Cu (In 1-x-y} Al x Ga y) S 2 quantum dot phosphor of the present invention, when using the preferred starting material in the above reaction conditions, are synthesized by the chemical reaction of equation (I).

_{CuI + (1-x-y} ) · In (CH 3 COO) 3 + x · Al (CH 3 COO) 3 + y · Ga (CH 3 COO) 3 +2 · CH 3 (CH 2) 11 SH
_{→ Cu (In 1-x-} y Al x Ga y) S 2 + ( unreacted materials and by-products) (I)
(In the formula, the ranges of Al concentration (x), Ga concentration (y) and x+y are within the above range)

After the reaction, after dispersing the synthesized quantum dot phosphor in a mixed liquid of chloroform and ethanol, which is a poor solvent, centrifuge several times using a centrifuge to separate each particle size (emission wavelength). Separate and purify. Finally, the quantum dot phosphor can be obtained in the form of a dispersion dispersed in a dispersion solvent such as chloroform or toluene.

_{(II) Cu (In 1-} x-y Al x Ga y) S 2 / ZnS as a synthetic raw material of the quantum dots phosphor, _Cu synthesized in _{(I) (In 1-x} -y Al x Ga y) S ₂ , as a Zn source, zinc organic acid, for example, zinc stearate (Zn(C ₁₇ H ₃₅ COO) ₂ ), zinc acetate (Zn(CH ₃ COO) ₂ ) and the like, and as a S source, dodecanethiol (CH Examples thereof include thiols such as ₃ (CH ₂ ) ₁₁ SH) and sulfur powder (S). The raw material, _Cu synthesized in _{(I) (In 1-x} -y Al x Ga y) S 2, zinc stearate, it is preferably used dodecanethiol.

The amount of each raw _{material, Cu (In 1-x-} y Al x Ga y) S 2: the molar ratio of ZnS is usually 1: 1 to 1:10, preferably 1: 1 to 1: 5, more preferably 1 : 1 to 1:2. The amount of the raw material of the S source is adjusted to be 1 mol or more with respect to 1 mol of Zn.

The solvent is not limited as long as it can be used by the solvothermal method, and examples thereof include dodecanethiol and octadecene. As the solvent, it is preferable to use dodecanethiol, which can also be used as the S source. The amount of solvent is adjusted so that the total amount of all raw materials is usually 90% by weight to 99% by weight, preferably 98% by weight to 99% by weight, based on the total weight of the reaction solution. When a compound that can be used as the S source is used as the solvent, the amount of the solvent is usually 85% by weight based on the total weight of the reaction solution (including the amount of the compound used as the S source). % To 99% by weight, preferably 95 to 99% by weight.

The synthesis temperature and the synthesis time may be different depending on the particle size of the quantum dot phosphor to be synthesized, and are not limited, but the synthesis temperature is usually adjusted at a temperature between 160° C. and 200° C. Is usually adjusted for a time between 6 and 24 hours.

The particle size can be increased by increasing the synthesis temperature and prolonging the synthesis time, and the particle size can be reduced by lowering the synthesis temperature and shortening the synthesis time.

The synthesis atmosphere is usually an atmosphere in which oxygen is blocked, and is, for example, an inert gas atmosphere such as nitrogen or argon.

_{Cu (In 1-x-y} Al x Ga y) S 2 / ZnS quantum dot phosphor of the present invention, when using the preferred starting material in the above reaction conditions, is synthesized by chemical reaction formula (II).

_{Cu (In 1-x-y} Al x Ga y) S 2 ( _{core) + Zn (C 17 H 35} COO) 2 + CH 3 (CH 2) 11 SH
_{→ Cu (In 1-x-} y Al x Ga y) S 2 / ZnS ( core / shell) + (unreacted materials and by-products) (II)
(In the formula, the ranges of Al concentration (x), Ga concentration (y) and x+y are within the above range)

In the reaction of (2), by coating the _{Cu (In 1-x-y} Al x Ga y) S 2 of the surface of the synthesized core, a ZnS shell as the shell (1), a core / shell structure _{Cu (In 1-x-y} Al x Ga y) S 2 / ZnS is synthesized with.

After the reaction, after dispersing the synthesized quantum dot phosphor in a mixed liquid of chloroform and ethanol, which is a poor solvent, centrifuge several times using a centrifuge to separate each particle size (emission wavelength). Separate and purify. Finally, the quantum dot phosphor can be obtained in the form of a dispersion dispersed in a dispersion solvent such as chloroform or toluene.

The _{Cu (In 1-x-y} Al x Ga y) S 2 / ZnS quantum dot phosphor of the present invention, crystal defects there are many _{Cu (In 1-x-y} Al x Ga y) of _{S 2} core crystals Is coated with ZnS, which has a larger bandgap than the core as a shell. Accordingly, the _{Cu (In 1-x-y} Al x Ga y) S 2 / ZnS quantum dot phosphor of the present invention, the surface defects are reduced, and the luminous efficiency is increased.

<Phosphor film>
FIG. 5 is a diagram schematically showing an example of a phosphor film in which the quantum dot phosphors 7A and 7B of the present invention are enclosed in a transparent resin 5A. The phosphor film shown in FIG. 5 is roughly composed of the quantum dot phosphors 7A and 7B of the present invention and the transparent resin 5A, and the quantum dot phosphors 7A and 7B of the present invention are uniformly dispersed in the transparent resin 5A. There is.

Quantum dot phosphors 7A of the present invention, the green emission wavelength (500 nm to 600 _nm: in _{Cu (In 1-x-y} Al x Ga y) S 2 quantum dot phosphor, with a particle size 2.0nm~4.5nm _There, in the _{Cu (in 1-x-y} Al x Ga y) S 2 / ZnS quantum dot phosphor has a particle size which is 3.0Nm～5.5Nm), quantum dot phosphor 7B of the present invention , red light emission wavelength (600 nm to 700 _nm: in _{Cu (in 1-x-y} Al x Ga y) S 2 quantum dot phosphor, a particle size 4.0nm~6.0nm, Cu _{(in 1-x-} in _{y Al x Ga y) S 2} / ZnS quantum dot phosphor has a particle size which is 5.0nm~7.0nm). The quantum dot phosphors 7A and 7B of the present invention are used by uniformly mixing them. As the mixing method, a conventional mixing method can be used.

As the transparent resin 5A, a room temperature curable type, a thermosetting type, or an ultraviolet curable type silicone resin, an epoxy resin, or the like that has been conventionally known in the art can be used.

The phosphor film shown in FIG. 5 can be prepared, for example, as follows.

First, the transparent resin 5A and the quantum dot phosphors 7A and 7B of the present invention are uniformly mixed using a defoaming stirrer to prepare a mixture for phosphor film preparation.
Then, the prepared mixture is thinly spread on a substrate using screen printing, a dispenser, a doctor blade or the like to form a phosphor film precursor.

The phosphor film precursor is then cured to form a phosphor film. For example, when a room temperature curable resin is used as the transparent resin 5A, the phosphor film precursor is cured at room temperature for about 6 hours to form a phosphor film, and a thermosetting resin is used as the transparent resin 5A. In this case, the phosphor film is formed by heating and curing at about 100 to 150° C. for about 1 to 6 hours. Form.

The thickness of the phosphor film is usually 50 μm to 400 μm, preferably 100 μm to 300 μm, more preferably 100 μm to 200 μm.

In addition to the quantum dot phosphor of the present invention, a quantum dot phosphor such as CdSe, CdSe/ZnS, InP, InP/ZnS can be mixed in the phosphor film.

By using the phosphor film containing the quantum dot phosphor of the present invention, it is possible to realize a light emitting device having a high light emitting efficiency and a liquid crystal display panel having a high light emitting efficiency using such a light emitting device.

<Light emitting device>
FIG. 6 is a diagram schematically showing an example of a light emitting device manufactured using the phosphor film containing the quantum dot phosphors 7A and 7B of the present invention shown in FIG. The light emitting device shown in FIG. 6 is roughly composed of a phosphor film 11, a blue LED 10, a reflection sheet 8 and a light guide 9. The light emitting device shown in FIG. 6 has a three-layer structure in which the light guide 9 is arranged between the phosphor film 11 and the reflection sheet 8, and the blue light emitted from the blue LED 10 is in the light guide 9. The blue LED 10 is arranged on one side surface of the layer so that the blue LED 10 can be spread while being guided by or guided by the light guide body 9 and reflected by the reflection sheet 8.

The blue light emitted from the blue LED 10 spreads while being guided through the light guide 9 or while being guided through the light guide 9 and reflected by the reflection sheet 8, and a part of the blue light is emitted from the phosphor film 11. Of the quantum dot phosphors 7A and 7B included in the phosphor film 11 and is transmitted through the phosphor film 11 as it is. The rest of the blue light emission is absorbed as excitation light for the quantum dot phosphors 7A and 7B included in the phosphor film 11, converted into green light emission by the quantum dot phosphor 7A, and red light emission by the quantum dot phosphor 7B. Is converted to. The blue light emitted from the blue LED 10 is mixed with the green light emitted from the quantum dot phosphors 7A and 7B and the red light emitted, and a uniform white light is emitted from the light emitting device.

In the light emitting device of FIG. 6, the blue light emitted from the blue LED 10 is efficiently spread by the light guide 9 and/or the reflection sheet 8, and a part of the spread light is contained in the phosphor film 11. The dot phosphors 7A and 7B are efficiently irradiated, and the irradiated light is efficiently absorbed by the quantum dot phosphors 7A and 7B of the present invention, and the quantum dot phosphor 7A of the present invention excited by the absorbed light And 7B efficiently emit green and red light.

FIG. 7 shows that in the light emitting device of FIG. 6, blue light emitted from the blue LED 10 spreads while being guided through the light guide body 9 or being guided through the light guide body 9 and being reflected by the reflection sheet 8. FIG. 9 is a diagram schematically showing an example of a light emitting device in which the blue LED 10 is arranged on two side surfaces facing each other so that the light emitting device shown in FIG. 7 can be used.

<Liquid crystal display panel>
FIG. 8 is a diagram schematically showing a liquid crystal display panel manufactured by using the light emitting device having the quantum dot phosphors 7A and 7B of the present invention shown in FIG. 6 as a backlight. The liquid crystal display panel shown in FIG. 8 is roughly composed of the light emitting device (backlight) shown in FIG. 6, two diffusion sheets 12, a prism sheet 13, two polarizing plates 14, a liquid crystal cell 15, and a color filter 16. .. In the liquid crystal display panel shown in FIG. 8, the white light emitted from the backlight passes through the diffusion sheet 12, the prism sheet 13, the diffusion sheet 12, the polarizing plate 14, the liquid crystal cell 15, the color filter 16, and the polarizing plate 14 in order. It has an arranged structure.

In the liquid crystal display panel of FIG. 8, the white light emitted from the backlight passes through the prism sheet 13 sandwiched between the diffusion sheets 12 to reduce the light unevenness and improve the brightness, and further to the polarizing plate 14. By passing through the liquid crystal cell 15 and the color filter 16 that are sandwiched, red, blue, and green can be emitted in each pixel. Although not shown in FIG. 8, the liquid crystal display panel is turned on by connecting a drive circuit.

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

(Study of quantum dot phosphor)
In the following comparative examples and examples, quantum dot phosphors were evaluated by comparing quantum efficiencies. In the present specification, quantum efficiency means the number of photons that emit light when one photon is absorbed. The quantum efficiency was measured by the following method.

<Quantum efficiency measurement method>
The synthesized quantum dot phosphor was dispersed in a toluene solvent to a concentration of 1 mg/ml or less, and the quantum efficiency was measured with an integrating sphere type quantum efficiency measuring device. In general, when the concentration is too high, a phenomenon (quantity quenching) that the quantum efficiency characteristic saturates with an increase in concentration is observed. Therefore, the measurement was performed at a sufficiently low concentration so that the concentration quenching did not occur.

(Comparative Example 1)
A CuInS ₂ quantum dot phosphor was synthesized by a solvothermal method using copper iodide, indium triacetate, and dodecanethiol as raw materials. In an inert gas atmosphere, the synthesis temperature is adjusted at a temperature of 160° C. to 200° C., the synthesis time is adjusted at 3 hours to 12 hours, and a quantum dot phosphor having a green emission wavelength (emission wavelength: 540 nm) And a quantum dot phosphor having a red emission wavelength (emission wavelength: 620 nm) were synthesized.

FIG. 9 shows the relationship between the particle diameter and the emission wavelength in the CuInS ₂ /ZnS-based quantum dot phosphor. From FIG. 9, for the CuInS ₂ /ZnS-based quantum dot phosphor, a quantum dot phosphor having a green emission wavelength was prepared by adjusting the particle size to 4.0 nm to 4.6 nm, and the particle size was set to 5 A quantum dot phosphor having a red emission wavelength was prepared by adjusting the wavelength to 0.2 nm to 5.8 nm. In the CuInS ₂ -based quantum dot phosphor, the relationship between the emission wavelength and the particle diameter is about 1 nm smaller than that in the CuInS ₂ /ZnS-based quantum dot phosphor, and the emission wavelength is the same. Was there. From this, in the CuInS ₂ -based quantum dot phosphor, by adjusting the particle size to 3.0 nm to 3.6 nm, a quantum dot phosphor having a green emission wavelength was prepared, and the particle size was 4.2 nm to. A quantum dot phosphor having a red emission wavelength was prepared by adjusting the wavelength to 4.8 nm. Also in Comparative Examples and Examples described below, quantum dot phosphors having respective emission wavelengths were similarly prepared.

About the obtained quantum dot fluorescent substance, the quantum efficiency at the time of making it light-emit using a blue LED (emission wavelength: 445 nm) as an excitation source was measured.

(Comparative example 2)
CuInS ₂ /ZnS was synthesized by the solvothermal method using the CuInS ₂ quantum dot phosphor synthesized in Comparative Example 1, zinc stearate, dodecanethiol, and octadecene as raw materials. In an inert gas atmosphere, the synthesis temperature is adjusted at a temperature of 160° C. to 200° C., the synthesis time is adjusted at 6 hours to 24 hours, and a quantum dot phosphor having an emission wavelength of green (emission wavelength: 540 nm) And a quantum dot phosphor having a red emission wavelength (emission wavelength: 620 nm) were synthesized.

About the obtained quantum dot fluorescent substance, the quantum efficiency at the time of making it light-emit with blue LED (emission wavelength: 445 nm) as an excitation source was measured.

(Example 1)
As raw materials, copper iodide, triacetate indium triacetate aluminum, and using dodecanethiol, by solvothermal method _{Cu (In 1-x-y} Al x Ga y) S 2 (0 <x ≦ 1 (x Was changed at 0.1 intervals), and y=0) quantum dot phosphor was synthesized. In an inert gas atmosphere, the synthesis temperature is adjusted at a temperature of 160° C. to 200° C., the synthesis time is adjusted at 3 hours to 12 hours, and a quantum dot phosphor having a green emission wavelength (emission wavelength: 540 nm) And a quantum dot phosphor having a red emission wavelength (emission wavelength: 620 nm) were synthesized.

About the obtained quantum dot fluorescent substance, the quantum efficiency at the time of making it light-emit using a blue LED (emission wavelength: 445 nm) as an excitation source was measured. FIG. 10 shows the relationship of the quantum efficiency (relative value) with respect to the Al concentration (x) for the quantum dot phosphor having a red emission wavelength. The quantum efficiency (relative value) is a value when the quantum efficiency is 1 when x=0. x=0 is Comparative Example 1. Than 10, the quantum efficiency of the red _Cu having an emission wavelength of _{(In 1-x-y Al} x Ga y) S 2 (0 <x ≦ 0.4, y = 0) quantum dot phosphor containing Al It can be confirmed that the quantum efficiency is higher than that of the quantum dot phosphor (Comparative Example 1). Similar results were also obtained with the quantum dot phosphor having a green emission wavelength.

FIG. 11 shows quantum efficiency (relative value) with respect to excitation wavelength for a quantum dot phosphor having red emission wavelength of x=0.3 and y=0, that is, Cu(In _0.7 Al _0.3 )S _2. Shows the relationship. The quantum efficiency (relative value) is a value when the quantum efficiency is 1 when the excitation wavelength is 300 nm. From FIG. 11, it can be confirmed that the quantum efficiency of the Cu(In _0.7 Al _0.3 )S ₂ quantum dot phosphor increases when the excitation wavelength is 350 nm to 450 nm. _{Therefore, Cu (In 1-x-} y Al x Ga y) S 2 (0 <x ≦ 0.4, y = 0) in the quantum dot phosphors, rather than using UV-LED as an excitation source, 380 nm to 450 nm The luminous efficiency can be improved by using a visible light emitting LED having an emission wavelength. Similar results were also obtained with the quantum dot phosphor having a green emission wavelength.

(Example 2)
Using _Cu synthesized in Example 1 as a starting material _{(In 1-x-y Al} x Ga y) S 2 (0 <x ≦ 1, y = 0) quantum dot phosphor, zinc stearate, dodecanethiol, and octadecene to (synthesized with modification 0 <x ≦ 1 (x 0.1 _{spacing), y = 0) Cu (} in 1-x-y Al x Ga y) S 2 / ZnS by solvothermal method quantum dots A phosphor was synthesized. In an inert gas atmosphere, the synthesis temperature is adjusted at a temperature of 160° C. to 200° C., the synthesis time is adjusted at 6 hours to 24 hours, and a quantum dot phosphor having an emission wavelength of green (emission wavelength: 540 nm) And a quantum dot phosphor having a red emission wavelength (emission wavelength: 620 nm) were synthesized.

About the obtained quantum dot fluorescent substance, the quantum efficiency at the time of making it light-emit using a blue LED (emission wavelength: 445 nm) as an excitation source was measured. FIG. 12 shows the relationship between the Al concentration (x) and the quantum efficiency (relative value) for a quantum dot phosphor having a red emission wavelength. The quantum efficiency (relative value) is a value when the quantum efficiency is 1 when x=0. x=0 is Comparative Example 2. Than 12, the quantum efficiency of the _{Cu (In 1-x-y} Al x Ga y) S 2 /ZnS(0<x≦0.4,y=0) quantum dot phosphor having a red emission wavelength, Al It can be confirmed that the quantum efficiency is higher than that of the quantum dot phosphor not containing (Comparative Example 2). Similar results were also obtained with the quantum dot phosphor having a green emission wavelength.

FIG. 13 shows the quantum efficiency (relative to the excitation wavelength) for the quantum dot phosphor having red emission wavelength of x=0.3 and y=0, that is, Cu(In _0.7 Al _0.3 )S ₂ /ZnS. Value). The quantum efficiency (relative value) is a value when the quantum efficiency is 1 when the excitation wavelength is 300 nm. From FIG. 13, it can be confirmed that the quantum efficiency of the Cu(In _0.7 Al _0.3 )S ₂ /ZnS quantum dot phosphor increases when the excitation wavelength is 350 nm to 450 nm. _Therefore, the _{(In 1-x-y Al} x Ga y) S 2 /ZnS(0<x≦0.4,y=0) quantum dot phosphors, rather than using UV-LED as an excitation source, 380 nm to The luminous efficiency can be improved by using a visible light emitting LED having an emission wavelength of 450 nm. Similar results were also obtained with the quantum dot phosphor having a green emission wavelength.

(Example 3)
As raw materials, copper iodide, triacetate indium triacetate gallium, and using dodecanethiol, by solvothermal method _{Cu (In 1-x-y} Al x Ga y) S 2 (x = 0,0 <y ≤1 (y was changed at intervals of 0.1) to synthesize quantum dot phosphors. In an inert gas atmosphere, the synthesis temperature is adjusted at a temperature of 160° C. to 200° C., the synthesis time is adjusted at 3 hours to 12 hours, and a quantum dot phosphor having a green emission wavelength (emission wavelength: 540 nm) And a quantum dot phosphor having a red emission wavelength (emission wavelength: 620 nm) were synthesized.

About the obtained quantum dot fluorescent substance, the quantum efficiency at the time of making it light-emit using a blue LED (emission wavelength: 445 nm) as an excitation source was measured. The relationship between the quantum efficiency (relative value) with respect to the Ga concentration (y) for the quantum dot phosphor having the red emission wavelength and the quantum dot phosphor having the green emission wavelength is as follows: The characteristics were similar to the efficiency (relative value) relationship. _Therefore, Cu quantum efficiency of the _{(In 1-x-y Al} x Ga y) S 2 (x = 0,0 <y ≦ 0.4) quantum dot phosphors, quantum dots phosphor containing no Ga (Comparative Example It is higher than the quantum efficiency of 1).

Further, y=0.3, y=0, that is, regarding the quantum dot phosphor having a red emission wavelength and the quantum dot phosphor having a green emission wavelength of Cu(In _0.7 Ga _0.3 )S ₂ . The relationship of the quantum efficiency (relative value) with respect to the excitation wavelength was similar to the relationship of the quantum efficiency (relative value) with respect to the excitation wavelength in FIG. 11. Therefore, the quantum efficiency of the Cu(In _0.7 Ga _0.3 )S ₂ quantum dot phosphor increases when the excitation wavelength is 350 nm to 450 nm. _Therefore, in the _{Cu (In 1-x-y} Al x Ga y) S 2 (x = 0,0 <y ≦ 0.4) quantum dot phosphors, rather than using UV-LED as an excitation source, 380 nm to 450 nm The luminous efficiency can be improved by using a visible light emitting LED having an emission wavelength.

(Example 4)
Using _Cu synthesized in Example 3 as a starting material _{(In 1-x-y Al} x Ga y) S 2 (x = 0,0 <y ≦ 1) quantum dot phosphor, zinc stearate, dodecanethiol, and octadecene to, by solvothermal method _{Cu (in 1-x-y} Al x Ga y) S 2 / ZnS (x = 0,0 <y ≦ 1 (y is synthesized by changing at 0.1 intervals)) quantum dots A phosphor was synthesized. In an inert gas atmosphere, the synthesis temperature is adjusted at a temperature of 160° C. to 200° C., the synthesis time is adjusted at 6 hours to 24 hours, and a quantum dot phosphor having an emission wavelength of green (emission wavelength: 540 nm) And a quantum dot phosphor having a red emission wavelength (emission wavelength: 620 nm) were synthesized.

About the obtained quantum dot fluorescent substance, the quantum efficiency at the time of making it light-emit using a blue LED (emission wavelength: 445 nm) as an excitation source was measured. The relationship between the quantum efficiency (relative value) with respect to the Ga concentration (y) for the quantum dot phosphor having a red emission wavelength and the quantum dot phosphor having a green emission wavelength is as follows: The characteristics were similar to the efficiency (relative value) relationship. _{Therefore, Cu (In 1-x-} y Al x Ga y) S 2 /ZnS(x=0,0<y≦0.4) quantum efficiency of the quantum dot phosphors, quantum dots phosphor containing no Ga ( It is higher than the quantum efficiency of Comparative Example 2).

Further, y=0.3, y=0, that is, a quantum dot phosphor having a red emission wavelength and a quantum dot phosphor having a green emission wavelength of Cu(In _0.7 Ga _0.3 )S ₂ /ZnS. The relationship of the quantum efficiency (relative value) with respect to the excitation wavelength of was a characteristic similar to the relationship of the quantum efficiency (relative value) with respect to the excitation wavelength in FIG. Therefore, the quantum efficiency of the Cu(In _0.7 Ga _0.3 )S ₂ /ZnS quantum dot phosphor increases when the excitation wavelength is 350 nm to 450 nm. _Therefore, in the _{Cu (In 1-x-y} Al x Ga y) S 2 /ZnS(x=0,0<y≦0.4) quantum dot phosphors, rather than using UV-LED as an excitation source, 380 nm The luminous efficiency can be increased by using a visible light emitting LED having an emission wavelength of up to 450 nm.

(Example 5)
As raw materials, copper iodide, triacetate indium triacetate aluminum triacetate gallium, and using _{dodecanethiol, Cu (In 1-x-} y Al x Ga y) by solvothermal method S 2 (0 <x + y ≦1, 0≦x≦1, 0≦y≦1 (x and y were changed at intervals of 0.1) to synthesize quantum dot phosphors. In an inert gas atmosphere, the synthesis temperature is adjusted at a temperature of 160° C. to 200° C., the synthesis time is adjusted at 3 hours to 12 hours, and a quantum dot phosphor having a green emission wavelength (emission wavelength: 540 nm) And a quantum dot phosphor having a red emission wavelength (emission wavelength: 620 nm) were synthesized.

About the obtained quantum dot fluorescent substance, the quantum efficiency at the time of making it light-emit using a blue LED (emission wavelength: 445 nm) as an excitation source was measured. From the relationship of the quantum efficiency (relative value) with respect to the Al concentration (x)+Ga concentration (y) for the quantum dot phosphor having a red emission wavelength and the quantum dot phosphor having a green emission wavelength, Cu(In _{1- x-y} Al _x Ga _y) quantum efficiency of the S 2 (0 <x + y ≦ 0.4) was found to be higher than the quantum efficiency of the quantum dot phosphor containing no Al and Ga (Comparative example 1).

In addition, x=0.15, y=0.15, that is, a quantum dot phosphor having a red emission wavelength of Cu(In _0.7 Al _0.15 Ga _0.15 )S ₂ and a green emission wavelength. From the relationship of the quantum efficiency (relative value) with respect to the excitation wavelength of the quantum dot phosphor, the excitation wavelength of Cu(In _0.7 Al _0.15 Ga _0.15 )S ₂ quantum dot phosphor is 350 nm to 450 nm. It was found that the quantum efficiency becomes high. _Therefore, in the _{Cu (In 1-x-y} Al x Ga y) S 2 (0 <x + y ≦ 0.4) quantum dot phosphors, rather than using UV-LED as an excitation source, the emission wavelength 380nm~450nm It is possible to increase the light emission efficiency by using the visible light emitting LED included therein.

(Example 6)
Material as synthesized in Example _{5 Cu (In 1-x-} y Al x Ga y) S 2 (0 <x + y ≦ 1,0 ≦ x ≦ 1,0 ≦ y ≦ 1) quantum dot phosphor, zinc stearate , using dodecane thiol, and _{octadecene, Cu (in 1-x-} y Al x Ga y) S 2 / ZnS (0 <x + y ≦ 1,0 ≦ x ≦ 1,0 ≦ y ≦ 1 by solvothermal method (X and y were changed at intervals of 0.1 to synthesize) Quantum dot phosphor was synthesized. In an inert gas atmosphere, the synthesis temperature is adjusted at a temperature of 160° C. to 200° C., the synthesis time is adjusted at 6 hours to 24 hours, and a quantum dot phosphor having an emission wavelength of green (emission wavelength: 540 nm) And a quantum dot phosphor having a red emission wavelength (emission wavelength: 620 nm) were synthesized.

About the obtained quantum dot fluorescent substance, the quantum efficiency at the time of making it light-emit using a blue LED (emission wavelength: 445 nm) as an excitation source was measured. From the relationship of the quantum efficiency (relative value) with respect to the Al concentration (x)+Ga concentration (y) for the quantum dot phosphor having a red emission wavelength and the quantum dot phosphor having a green emission wavelength, Cu(In _1- It was found that the quantum efficiency of _xy Al _x Gay )S _{2 /} ZnS ( _{0 <x+ y} ≦0.4) is higher than the quantum efficiency of the quantum dot phosphor containing no Al and Ga (Comparative Example 2). It was

Further, x=0.15, y=0.15, that is, a quantum dot phosphor having a red emission wavelength of Cu(In _0.7 Al _0.15 Ga _0.15 )S ₂ /ZnS and a green emission wavelength. From the relationship of the quantum efficiency (relative value) with respect to the excitation wavelength of the quantum dot phosphor having the following, the excitation wavelength of the Cu(In _0.7 Al _0.15 Ga _0.15 )S ₂ /ZnS quantum dot phosphor is It was found that the quantum efficiency becomes high at 350 nm to 450 nm. _Therefore, in the _{Cu (In 1-x-y} Al x Ga y) S 2 /ZnS(0<x+y≦0.4) quantum dot phosphors, rather than using UV-LED as an excitation source, emitting in 380nm~450nm The luminous efficiency can be improved by using the visible light emitting LED having a wavelength.

(Examination of liquid crystal display panel)
In the following comparative examples and examples, liquid crystal display panels were evaluated by comparing white light emission intensities. The white emission intensity was measured by the following method.

<Method of measuring white emission intensity>
Using a spectroscopic luminance meter, measure the chromaticity (x, y) values when each color (blue, green, red) cell is lit, calculate the color reproduction range (NTSC ratio), and the color reproduction range is 100% NTSC ratio. The concentration of the quantum dot phosphor in the phosphor film was appropriately adjusted so that As the white light emission intensity, a luminance value (relative value) when the emission color was adjusted so that the chromaticity during lighting was (x, y)=(0.33, 0.33) was used.

(Comparative example 3)
Blue LED (emission wavelength: 445 nm), CuInS ₂ quantum dot phosphor having an emission wavelength of the green prepared in Comparative Example 1 (emission wavelength: 540 nm) and red CuInS ₂ quantum dot phosphor having an emission wavelength (emission wavelength: 620 nm), the concentration of the quantum dot phosphor in the phosphor film was appropriately adjusted so that the color reproduction range was 100% in the NTSC ratio, and the liquid crystal display panel shown in FIG. 8 was manufactured.

The white emission intensity of the liquid crystal display panel of Comparative Example 3 was measured, and the obtained result was set as 100 and compared with the white emission intensity of the liquid crystal display panels of Examples 7 to 9.

(Example 7)
A blue LED (emission wavelength: 445 nm), a Cu(In _0.7 Al _0.3 )S ₂ quantum dot phosphor (emission wavelength: 540 nm) having a green emission wavelength prepared in Example 1 and a red emission wavelength were used. Using the Cu(In _0.7 Al _0.3 )S ₂ quantum dot phosphor (emission wavelength: 620 nm) that it has, the concentration of the quantum dot phosphor in the phosphor film such that the color reproduction range is 100% NTSC ratio. Were adjusted appropriately to manufacture the liquid crystal display panel shown in FIG.

As a result of the white light emission intensity measurement, the white light emission intensity of the liquid crystal display panel of Example 7 was 150 with respect to the white light emission intensity (100) of Comparative Example 3.

(Example 8)
A blue LED (emission wavelength: 445 nm), a Cu(In _0.7 Ga _0.3 )S ₂ quantum dot phosphor (emission wavelength: 540 nm) having a green emission wavelength prepared in Example 3, and a red emission wavelength were used. Using the Cu(In _0.7 Ga _0.3 )S ₂ quantum dot phosphor (emission wavelength: 620 nm) that it has, the concentration of the quantum dot phosphor in the phosphor film so that the color reproduction range is 100% NTSC ratio. Were adjusted appropriately to manufacture the liquid crystal display panel shown in FIG.

As a result of the white light emission intensity measurement, the white light emission intensity of the liquid crystal display panel of Example 8 was 145 with respect to the white light emission intensity (100) of Comparative Example 3.

(Example 9)
Blue LED (emission wavelength: 445 nm), Cu(In _0.7 Al _0.15 Ga _0.15 )S ₂ quantum dot phosphor (emission wavelength: 540 nm) having a green emission wavelength prepared in Example 5, and red Using a Cu(In _0.7 Al _0.15 Ga _0.15 )S ₂ quantum dot phosphor (emission wavelength: 620 nm) having an emission wavelength of 100 nm, the phosphor has a color reproduction range of 100% NTSC ratio. The concentration of the quantum dot phosphor in the film was appropriately adjusted to manufacture the liquid crystal display panel shown in FIG.

As a result of the white light emission intensity measurement, the white light emission intensity of the liquid crystal display panel of Example 9 was 135 with respect to the white light emission intensity (100) of Comparative Example 3.

(Comparative example 4)
Blue LED (emission wavelength: 445nm), CuInS ₂ / ZnS quantum dot phosphor having a green emission wavelength prepared in Comparative Example 2 (emission wavelength: 540 nm) and red CuInS ₂ / ZnS quantum dot phosphor having an emission wavelength (Emission wavelength: 620 nm) was used to appropriately adjust the concentration of the quantum dot phosphor in the phosphor film so that the color reproduction range was 100% in NTSC ratio, and the liquid crystal display panel shown in FIG. 8 was manufactured.

The white emission intensity of the liquid crystal display panel of Comparative Example 4 was measured, and the obtained result was set as 100 and compared with the white emission intensity of the liquid crystal display panels of Examples 10-12.

(Example 10)
Blue LED (emission wavelength: 445 nm), Cu(In _0.7 Al _0.3 )S ₂ /ZnS quantum dot phosphor (emission wavelength: 540 nm) having a green emission wavelength prepared in Example 2, and red emission. Quantum dots in a phosphor film using a Cu(In _0.7 Al _0.3 )S ₂ /ZnS quantum dot phosphor having a wavelength (emission wavelength: 620 nm) so that the color reproduction range is 100% NTSC ratio. The liquid crystal display panel shown in FIG. 8 was manufactured by appropriately adjusting the concentration of the phosphor.

As a result of the white light emission intensity measurement, the white light emission intensity of the liquid crystal display panel of Example 10 was 107 with respect to the white light emission intensity (100) of Comparative Example 4.

(Example 11)
Blue LED (emission wavelength: 445 nm), Cu(In _0.7 Ga _0.3 )S ₂ /ZnS quantum dot phosphor (emission wavelength: 540 nm) having a green emission wavelength prepared in Example 4, and red emission Quantum dots in a phosphor film using a Cu(In _0.7 Ga _0.3 )S ₂ /ZnS quantum dot phosphor having a wavelength (emission wavelength: 620 nm) so that the color reproduction range is 100% in NTSC ratio. The liquid crystal display panel shown in FIG. 8 was manufactured by appropriately adjusting the concentration of the phosphor.

As a result of the white light emission intensity measurement, the white light emission intensity of the liquid crystal display panel of Example 11 was 105 with respect to the white light emission intensity (100) of Comparative Example 4.

(Example 12)
Blue LED (emission wavelength: 445 nm), Cu(In _0.7 Al _0.15 Ga _0.15 )S ₂ /ZnS quantum dot phosphor (emission wavelength: 540 nm) having a green emission wavelength prepared in Example 6 And Cu(In _0.7 Al _0.15 Ga _0.15 )S ₂ /ZnS quantum dot phosphor (emission wavelength: 620 nm) having an emission wavelength of red, the color reproduction range is 100% in NTSC ratio. Thus, the concentration of the quantum dot phosphor in the phosphor film was appropriately adjusted to manufacture the liquid crystal display panel shown in FIG.

As a result of the white light emission intensity measurement, the white light emission intensity of the liquid crystal display panel of Example 12 was 106 with respect to the white light emission intensity (100) of Comparative Example 4.

(Comparative example 5)
Blue LED (emission wavelength: 445 nm), InP/ZnS quantum dot phosphor having a green emission wavelength (emission wavelength: 540 nm), and CuInS ₂ /ZnS quantum dot phosphor having a red emission wavelength prepared in Comparative Example 2 (Emission wavelength: 620 nm) was used to appropriately adjust the concentration of the quantum dot phosphor in the phosphor film so that the color reproduction range was 100% in NTSC ratio, and the liquid crystal display panel shown in FIG. 8 was manufactured.
The InP/ZnS quantum dot phosphor was prepared by using a solvothermal method (J. Phys. Chem. C 2008, 112, 20110).

The white light emission intensity of the liquid crystal display panel of Comparative Example 5 was measured, and the obtained result was set as 100 and compared with the white light emission intensity of the liquid crystal display panels of Examples 13 to 15.

(Example 13)
It has a blue LED (emission wavelength: 445 nm), an InP/ZnS quantum dot phosphor having a green emission wavelength (emission wavelength: 540 nm: the one described in Comparative Example 5), and a red emission wavelength prepared in Example 2. Using a Cu(In _0.7 Al _0.3 )S ₂ /ZnS quantum dot phosphor (emission wavelength: 620 nm), the color reproduction range of the quantum dot phosphor in the phosphor film was set to 100% NTSC ratio. The liquid crystal display panel shown in FIG. 8 was manufactured by appropriately adjusting the density.

As a result of the white light emission intensity measurement, the white light emission intensity of the liquid crystal display panel of Example 13 was 106 with respect to the white light emission intensity (100) of Comparative Example 5.

(Example 14)
It has a blue LED (emission wavelength: 445 nm), an InP/ZnS quantum dot phosphor having an emission wavelength of green (emission wavelength: 540 nm, the one described in Comparative Example 5), and an emission wavelength of red prepared in Example 4. Using Cu(In _0.7 Ga _0.3 )S ₂ /ZnS quantum dot phosphor (emission wavelength: 620 nm), the color reproduction range of the quantum dot phosphor in the phosphor film was set to 100% NTSC ratio. The liquid crystal display panel shown in FIG. 8 was manufactured by appropriately adjusting the density.

As a result of the white light emission intensity measurement, the white light emission intensity of the liquid crystal display panel of Example 14 was 105 with respect to the white light emission intensity (100) of Comparative Example 5.

(Example 15)
It has a blue LED (emission wavelength: 445 nm), an InP/ZnS quantum dot phosphor having an emission wavelength of green (emission wavelength: 540 nm, the one described in Comparative Example 5), and an emission wavelength of red prepared in Example 6. Using a Cu(In _0.7 Al _0.15 Ga _0.15 )S ₂ /ZnS quantum dot phosphor (emission wavelength: 620 nm), the quantum in the phosphor film was adjusted so that the color reproduction range was 100% NTSC ratio. The liquid crystal display panel shown in FIG. 8 was manufactured by appropriately adjusting the concentration of the dot phosphor.

As a result of the white light emission intensity measurement, the white light emission intensity of the liquid crystal display panel of Example 15 was 105 with respect to the white light emission intensity (100) of Comparative Example 5.

(Comparative example 6)
Blue LED (emission wavelength: 445 nm), CdSe/ZnS quantum dot phosphor having a green emission wavelength (emission wavelength: 540 nm), and CuInS ₂ /ZnS quantum dot phosphor having a red emission wavelength prepared in Comparative Example 2 (Emission wavelength: 620 nm) was used to appropriately adjust the concentration of the quantum dot phosphor in the phosphor film so that the color reproduction range was 100% in NTSC ratio, and the liquid crystal display panel shown in FIG. 8 was manufactured.
The CdSe/ZnS quantum dot phosphor was produced using the solvothermal method (J. Phys. Chem. 1996, 100, 468).

The white emission intensity of the liquid crystal display panel of Comparative Example 6 was measured, and the obtained result was set as 100 and compared with the white emission intensity of the liquid crystal display panels of Examples 16-18.

(Example 16)
It has a blue LED (emission wavelength: 445 nm), a CdSe/ZnS quantum dot phosphor having a green emission wavelength (emission wavelength: 540 nm, the one described in Comparative Example 6), and a red emission wavelength prepared in Example 2. Using a Cu(In _0.7 Al _0.3 )S ₂ /ZnS quantum dot phosphor (emission wavelength: 620 nm), the color reproduction range of the quantum dot phosphor in the phosphor film was set to 100% NTSC ratio. The liquid crystal display panel shown in FIG. 8 was manufactured by appropriately adjusting the density.

As a result of the white light emission intensity measurement, the white light emission intensity of the liquid crystal display panel of Example 16 was 105 with respect to the white light emission intensity (100) of Comparative Example 6.

(Example 17)
It has a blue LED (emission wavelength: 445 nm), a CdSe/ZnS quantum dot phosphor having a green emission wavelength (emission wavelength: 540 nm, the one described in Comparative Example 6), and a red emission wavelength prepared in Example 4. Using Cu(In _0.7 Ga _0.3 )S ₂ /ZnS quantum dot phosphor (emission wavelength: 620 nm), the color reproduction range of the quantum dot phosphor in the phosphor film was set to 100% NTSC ratio. The liquid crystal display panel shown in FIG. 8 was manufactured by appropriately adjusting the density.

As a result of the white light emission intensity measurement, the white light emission intensity of the liquid crystal display panel of Example 17 was 102 with respect to the white light emission intensity (100) of Comparative Example 6.

(Example 18)
It has a blue LED (emission wavelength: 445 nm), a CdSe/ZnS quantum dot phosphor having a green emission wavelength (emission wavelength: 540 nm, the one described in Comparative Example 6), and a red emission wavelength prepared in Example 6. Using a Cu(In _0.7 Al _0.15 Ga _0.15 )S ₂ /ZnS quantum dot phosphor (emission wavelength: 620 nm), the quantum in the phosphor film was adjusted so that the color reproduction range was 100% NTSC ratio. The liquid crystal display panel shown in FIG. 8 was manufactured by appropriately adjusting the concentration of the dot phosphor.

As a result of the white light emission intensity measurement, the white light emission intensity of the liquid crystal display panel of Example 18 was 102 with respect to the white light emission intensity (100) of Comparative Example 6.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications are included. For example, a part of the configuration of the embodiment can be added/deleted/replaced with another configuration.

1 blue LED chip, 2 wire, 3 lead frame, 4 case, 5 transparent resin, 5A transparent resin, 6 heat sink, 7 phosphor particles, 7A quantum dot phosphor having green emission wavelength, 7B having red emission wavelength Quantum dot phosphor, 8 reflective sheet, 9 light guide, 10 blue LED, 11 phosphor film, 12 diffusion sheet, 13 prism sheet, 14 polarizing plate, 15 liquid crystal cell, 16 color filter

Claims (8)

_{Cu (In 1-x-y} Al x Ga y) S 2 (0.1 ≦ x + y ≦ 0.4,0.1 ≦ x ≦ 0.4,0 ≦ y ≦ 0.3)
Quantum dot phosphor represented by. x+y is in a range of 0.1≦x+y≦0.3, x is in a range of 0.1≦x≦0.3, and y is in a range of 0≦y≦ 0.2. The described quantum dot phosphor. The quantum dot phosphor according to claim 1, having an average particle diameter of 1 nm to 10 nm. _{Cu (In 1-x-y} Al x Ga y) S 2 /ZnS(0.1≦x+y≦0.4,0.1≦x≦0.4,0≦y≦ 0.3)
Quantum dot phosphor represented by. The quantum dot phosphor according to claim 4, wherein x+y is in a range of 0.2≦x+y≦0.4. The quantum dot phosphor according to claim 4, having an average particle diameter of 1 nm to 10 nm. A light emitting element, a light guide that guides light from the light emitting element, a reflection sheet that reflects the light guided by the light guide, and light and/or the light that has been guided through the light guide. A phosphor film including a quantum dot phosphor that is excited by a part of light reflected by the reflection sheet by guiding an optical body,
The light emitting device has an emission wavelength between 300 nm and 500 nm,
The quantum dot phosphor is the quantum dot phosphor according to any one of claims 1 to 6,
The quantum dot phosphor has an emission wavelength between 500 nm and 800 nm,
Outputting light that is a mixture of light having a peak emission wavelength between 300 nm and 500 nm from the light emitting element and light having a peak emission wavelength between 500 nm and 800 nm from the quantum dot phosphor.
Light emitting device. The light emitting device according to claim 7, wherein the light emitting element has an emission wavelength between 380 nm and 450 nm.

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