JP7011202B2 - Luminescent device - Google Patents

Description

The present invention relates to a light emitting device, particularly a light emitting element that emits blue light, and a light emitting device that includes a quantum dot that absorbs a part of the blue light emitted by the light emitting element and emits green light.

As a light emitting device that emits white light, a light emitting element that emits blue light and a green phosphor that absorbs a part of the blue light emitted by the light emitting element and emits green light (or yellow-green fluorescence that emits yellowish green). A light emitting device including a body) and a red phosphor that absorbs a part of the blue light emitted by the light emitting element and emits red light has been conventionally known. Light emitting devices that emit such white light are used in various applications such as backlights and lighting devices for various displays such as liquid crystal displays.

In recent years, light emitting devices have been developed in which all or part of a phosphor is replaced with quantum dots (QDs). Quantum dots are semiconductor particles having a diameter of several nm to several tens of nm, and like a phosphor, they absorb light such as the blue light emitted by a light emitting element and emit light different from the absorbed light. ..
The green quantum dot that absorbs the blue light emitted by the light emitting element and emits green light and the red that absorbs the blue light emitted by the light emitting element and emits red light without containing the green phosphor and the red phosphor. A light emitting device including a quantum dot is known. Further, Patent Document 1 discloses a light emitting device including a yellow-green phosphor and red quantum dots.

Quantum dots are characterized in that their emission peaks are sharp, that is, the half width of the emission peaks is small (narrow). Therefore, the light emitting device using the quantum dots has an advantage that the color reproduction range becomes wide when combined with a color filter such as a liquid crystal display. Furthermore, by associating the peak wavelength of the color filter (the wavelength at which the transmittance peaks) with the emission peak of the quantum dots, more light can pass through the color filter, so that light is attenuated when the color filter is used. The light extraction efficiency is improved.
In particular, since the emission peaks of the conventional green and yellow-green phosphors are broad, these effects can be obtained more remarkably by using the green quantum dots.

Japanese Unexamined Patent Publication No. 2008-544553

However, in the conventional light emitting device using such quantum dots, red quantum dots are used, which causes a problem of causing secondary absorption. That is, the red quantum dots absorb a part of the green light (or yellow-green light) emitted by the green quantum dots or the green phosphor (or the yellow-green phosphor) that has absorbed the blue light, and emit the red light. When such secondary absorption occurs, there is a problem that the luminous efficiency of the entire light emitting device is lowered.
On the other hand, in many applications such as displays and lighting devices, there is a demand for a light emitting device capable of emitting brighter light with less power consumption, that is, having higher luminous efficiency.

The present invention has been made to meet such a demand, and provides a light emitting device using quantum dots, particularly green quantum dots, and having high luminous efficiency.

A light emitting element that emits blue light, a quantum dot that absorbs a part of the blue light emitted by the light emitting element and emits green light, and a composition thereof are represented by the following general formula (1), and the light emitting element of the light emitting element. The KSF phosphor that absorbs a part of the emitted blue light and emits red light and its composition are represented by the following general formula (2), and absorb a part of the blue light emitted by the light emitting element and emit red light. A light emitting device comprising at least one of an MGF phosphor that emits light.

A ₂ [M _1-a Mn ^{4 +} _a F ₆ ] (1)
(In the formula, A is at least one selected from the group consisting of K ⁺ , Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ and NH ₄ ⁺ , and M is from Group 4 and Group 14 elements. It is at least one element selected from the group, and a is satisfied with 0 <a <0.2.)

(X-a) MgO · (a / 2) Sc ₂ O ₃ · yMgF ₂ · cCaF ₂ · (1-b) GeO ₂ · (b / 2) Mt ₂ O ₃ : zMn ⁴⁺ (2)
(In the formula, x, y, z, a, b, c are 2.0 ≦ x ≦ 4.0, 0 <y <1.5, 0 <z <0.05, 0 ≦ a <0.5, Satisfying 0 <b <0.5, 0 ≦ c <1.5, y + c <1.5, and Mt is at least one selected from Al, Ga, and In.)

It is possible to provide a light emitting device using quantum dots, particularly green quantum dots, which has high luminous efficiency.

FIG. 1 is a schematic cross-sectional view of a light emitting device 100 according to the first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of the light emitting device 100A according to the second embodiment of the present invention. FIG. 3 is a schematic cross-sectional view for explaining the advantages of the light emitting device 100, and FIG. 3A is a schematic cross-sectional view showing an embodiment in which the red phosphor 14 is arranged inside the sealing resin 12. 3 (b) is a schematic cross-sectional view showing an embodiment in which the red phosphor 14 is arranged inside the translucent material 22. FIG. 4 is a schematic cross-sectional view showing a liquid crystal display 200 using the light emitting device 100B according to the third embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, it should be noted that the embodiments described below are for embodying the technical idea of the present invention and are not intended to limit the technical scope of the present invention. The configurations described in one embodiment are applicable to other embodiments unless otherwise specified. In the following description, terms indicating a specific direction or position (eg, "top", "bottom", "right", "left" and other terms including those terms) are used as needed, but they are used. The use of these terms is to facilitate understanding of the invention with reference to the drawings, and the meaning of those terms does not limit the technical scope of the invention.
It should be noted that the size and positional relationship of the members shown in each drawing may be exaggerated for the sake of clarity. Further, the parts having the same reference numerals appearing in a plurality of drawings indicate the same parts or members. Further, for example, a member indicated by a code consisting of a number and an alphabet, such as the code "10A", has the same number and does not have an alphabet, for example, the code "10", unless otherwise specified. It may have the same configuration as the member indicated by and the member indicated by the code having the same number and a different alphabet.

As a result of diligent studies, the inventor of the present application has obtained high luminous efficiency using green quantum dots by using at least one of KSF phosphor and MGF phosphor as the red phosphor instead of using red quantum dots. We have found that we can provide a luminous device with a light emitting device. The KSF phosphor and the MGF phosphor, which will be described in detail later, absorb the blue light emitted by the light emitting element and emit red light, but hardly absorb the green light emitted by the green quantum dots. That is, it does not cause secondary absorption. Therefore, the light emitting device according to the embodiment of the present invention has high luminous efficiency. Further, the peak in the emission spectra of the KSF phosphor and the MGF phosphor has a narrow half-value width of about 10 to 20 nm. Therefore, even when a color filter that transmits almost the entire wavelength range of red is passed through, red with a narrow half-value width can be obtained, so that red light with high color purity can be obtained.
The light emitting device according to the plurality of embodiments of the present invention will be described in detail below.

1. 1. Embodiment 1
FIG. 1 is a schematic cross-sectional view of a light emitting device 100 according to the first embodiment of the present invention. The light emitting device 100 includes a light emitting element 1 that emits blue light, a green quantum dot 24 that absorbs a part of the blue light emitted by the light emitting element 1 and emits green light, and a part of the blue light emitted by the light emitting element 1. Contains a red phosphor 14 that absorbs and emits red light. The red fluorophore 14 is at least one of the KSF and MGF phosphors, the details of which will be described later.

In the light emitting device according to the present invention, the positional relationship between the red phosphor 14 and the green quantum dot 24 with respect to the light emitting element 1 is not particularly limited. That is, (1) the red phosphor 14 may be located closer to the green quantum dot 24 with respect to the light emitting element 1, and (2) the red phosphor 14 may be located closer to the light emitting element 1. , The green quantum dot 24 may be located farther than the green quantum dot 24, and (3) the red phosphor 14 and the green quantum dot 24 are located at substantially the same distance from the light emitting element 1 as in the second embodiment described later. You can do it.
In the first embodiment, the red phosphor 14 is located closer to the green quantum dot 24 with respect to the light emitting element 1.

The light emitting device 100 includes a light emitting element package 10. The light emitting element package 10 includes a resin package 3 having a bottom surface, a side wall, and a cavity surrounded by the bottom surface and the side wall and having an open upper portion, and a light emitting element 1 arranged on the bottom surface of the cavity of the resin package 3. It has a sealing resin 12 filled in the cavity of the resin package 3. The positive electrode and the negative electrode of the light emitting element 1 are connected to an external power source via a conductive means such as a metal wire, a metal bump, or plating, and emits blue light by supplying a current (electric power) from the external power source. do. The sealing resin 12 covers the periphery of the light emitting element 1 (in the embodiment shown in FIG. 1, the upper surface and the side surface excluding the bottom surface of the light emitting element 1). The sealing resin 12 contains the red phosphor 14. That is, the red phosphor 14 is dispersed and arranged inside the sealing resin 12.
In the embodiment shown in FIG. 1, the red phosphor 14 is uniformly dispersed in the sealing resin 12, but the form of the dispersed arrangement of the red phosphor is not limited to this. The red phosphor 14 may be arranged at a higher density in a part of the sealing resin 12, for example, it is arranged at a higher density in the vicinity of the light emitting element 1. As such an arrangement, there is a so-called settling arrangement in which the dispersion density of the red phosphor is small at the upper part of the sealing resin and high at the bottom of the sealing resin 12 (including directly above the light emitting element 1). In the sedimentation arrangement, for example, the sealing resin 12 before curing, in which the red phosphor 14 is uniformly dispersed, is filled in the cavity of the resin package 3, and then the sealing resin 12 is left uncured for a predetermined time. It can be formed by curing the sealing resin 12 after the red phosphor 14 in the sealing resin 12 moves by gravity and its distribution becomes high at the bottom of the sealing resin 12. It may be settled by centrifugal force.

The light emitting element package 10 emits blue light and red light with its upper surface as an emission surface. More specifically, a part of the blue light emitted from the light emitting element 1 passes through the sealing resin 12 and is emitted outward from the upper surface of the sealing resin 12. Even if a part of the blue light emitted from the light emitting element package 10 is reflected on the side surface and / or the bottom surface of the resin package 3 as it travels inside the sealing resin 12, it is emitted from the upper surface of the sealing resin 12. good. Further, another part of the blue light emitted from the light emitting element 1 is absorbed by the red phosphor 14 while traveling inside the sealing resin 12, and the red phosphor 14 emits red light. Then, the red light emitted from the red phosphor 14 passes through the sealing resin 12 and is emitted outward from the upper surface of the sealing resin 12. A part of the red light emitted by the red phosphor 14 may be reflected from the side surface and / or the bottom surface of the resin package 3 as it travels inside the sealing resin 12, and then emitted from the upper surface of the sealing resin 12. ..

The green quantum dot-containing layer 20 is arranged on the outside of the sealing resin 12, that is, on the upper portion of the sealing resin 12 (or the resin package 3) in FIG. The green quantum dot-containing layer 20 includes the translucent material 22 and the green quantum dots 24. That is, the green quantum dots 24 are dispersedly arranged in the translucent material 22. The green quantum dot-containing layer 20 may have any form. One of the preferred forms is a sheet shape (or film shape) as shown in FIG. This is because the thickness of the green quantum dot-containing layer 20 can be made uniform and color unevenness can be suppressed.

With such a configuration, in the light emitting device 100, the red phosphor 14 is located closer to the green quantum dot 24 with respect to the light emitting element 1. A KSF or MGF fluorophore having a large particle size (or diameter) of, for example, 20 to 50 μm is placed near the light emitting element, and green quantum dots 24 having a particle size (or diameter) of, for example, 2 to 10 nm are arranged. By arranging it near the light emitting element 1, it is possible to suppress the scattering of light, particularly the scattering of green light by the red phosphor 14, and as a result, the light extraction efficiency (that is, the light emission efficiency) can be further improved.
The improvement of the light extraction efficiency will be described in detail after explaining the configuration of the second embodiment described later.

Most of the red light emitted from the upper surface of the light emitting element package 10 enters the inside from the lower surface of the green quantum dot-containing layer 20, passes through the translucent material 22 of the green quantum dot-containing layer 20, and then contains the green quantum dots. It goes out from the upper surface of the layer 20.
Most of the blue light emitted from the upper surface of the light emitting element package 10 enters the inside from the lower surface of the green quantum dot-containing layer 20. A part of the blue light that has entered the inside from the lower surface of the green quantum dot-containing layer 20 passes through the translucent material 22 of the green quantum dot-containing layer 20 and then goes out from the upper surface of the green quantum dot-containing layer 20. .. Another part of the blue light that has entered the inside from the lower surface of the green quantum dot-containing layer 20 is absorbed by the green quantum dots 24, and the green quantum dots 24 emit green light. Most of the green light emitted by the green quantum dots 24 travels inside the translucent material 22 and exits outside the upper surface of the green quantum dot-containing layer 20. As a result, on the outside of the upper surface of the green quantum dot-containing layer 20, blue light, red light, and green light are mixed to obtain white light.

A part of the green light emitted by the green quantum dots 24 travels downward, exits from the lower surface of the green quantum dot-containing layer 20, and enters the inside of the sealing resin 12 from the upper surface of the light emitting element package 10. However, the red fluorescent substance 14, which is at least one of the KSF fluorescent substance and the MGF fluorescent substance, does not easily absorb green light. Therefore, for example, after being reflected by the inner surface of the resin package 3, the green color is emitted from the upper surface of the light emitting element package 10, enters from the lower surface of the green quantum dot-containing layer 20, and is emitted from the upper surface of the green quantum dot-containing layer 20. There is light. The presence of such green light contributes to the improvement of the extraction efficiency of the light emitting device 100.

In the embodiment shown in FIG. 1, the green quantum dot-containing layer 20 and the sealing resin 12 (or the resin package 3) are separated from each other. This has the effect of more reliably suppressing the heat generation of the light emitting element 1 from being transmitted to the heat-sensitive green quantum dots 24.
However, the present invention is not limited to this, and the green quantum dot-containing layer 20 and the sealing resin 12 (or the resin package 3) may be in contact with each other. In this case, more light emitted from the light emitting element package 10 enters the green quantum dot-containing layer 20, and the extraction efficiency can be further improved. Further, even if the green quantum dot-containing layer 20 and the sealing resin 12 (or the resin package 3) are in contact with each other, the light emitting element 1 and the green quantum dot 24 are separated from each other to some extent. The effect of suppressing thermal deterioration can be obtained.

In the embodiment shown in FIG. 1, the mounting surface of the light emitting element package 10 is the bottom surface (lower surface), and the surface opposite to the light extraction surface is the mounting surface (for example, the upper surface is the light extraction surface). This is a top-view type light emitting element package (with the lower surface as the mounting surface). However, the present invention is not limited to this, and the light emitting element package 10 may be configured as a so-called side view type in which a surface adjacent to the light extraction surface is used as a mounting surface.
Further, in the embodiment shown in FIG. 1, the light emitting element package 10 including the resin package 3 is used, but the present invention is not limited thereto. Instead of the light emitting element package 10, a so-called packageless form may be used in which a phosphor layer containing a red phosphor 14 is formed on the surface of the light emitting element 1 without using a resin package.

Next, the details of each element of the light emitting device 100 will be shown.
1) Light emitting element The light emitting element 1 may be any known light emitting element and may be a blue LED chip as long as it emits blue light (the emission peak wavelength is in the range of 435 to 465 nm). The light emitting device 1 may include a semiconductor laminate, preferably a nitride semiconductor laminate. The semiconductor laminate (preferably a nitride semiconductor laminate) may have a first semiconductor layer (for example, an n-type semiconductor layer), a light emitting layer, and a second semiconductor layer (for example, a p-type semiconductor layer) in order.
Specifically, In _X Al _Y Ga _1-XY N (0 ≦ X, 0 ≦ Y, X + Y ≦ 1) may be used as the preferred nitride semiconductor material. As the film thickness and layer structure of each layer, those known in the art may be used.

2) Red phosphor The red fluorescent substance 14 is at least one of a KSF fluorescent substance and an MGF fluorescent substance. KSF and MGF fluorophores have the advantage of absorbing little green light and thus producing little secondary absorption. Further, the half width of the emission peak is as small as 35 nm or less, preferably 10 nm or less. The KSF and MGF phosphors will be described in detail below.

(KSF phosphor)
The KSF fluorophore is a red fluorophore whose emission wavelength peak is in the range of 610 to 650 nm. The composition is represented by the following general formula (1).

A ₂ [M _1-a Mn ^{4 +} _a F ₆ ] (1)
(In the formula, A is at least one selected from the group consisting of K ⁺ , Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ and NH ₄ ⁺ , and M is from Group 4 and Group 14 elements. It is at least one element selected from the group, and a is satisfied with 0 <a <0.2.)

The half width of the emission peak of the KSF phosphor is 10 nm or less.
Regarding this KSF phosphor, Japanese Patent Application No. 2014-122888, which the applicant of the present application filed for a patent earlier, may be referred to.

An example of a method for producing a KSF phosphor will be described. First, KHF ₂ and K ₂ MnF ₆ are weighed so as to have a desired composition ratio. The weighed KHF ₂ is dissolved in an HF aqueous solution to prepare a solution A. Further, the weighed K ₂ MnF ₆ is dissolved in an HF aqueous solution to prepare a solution B. Further, an aqueous solution containing H ₂ SiF ₆ is prepared so as to have a desired composition ratio to obtain a solution C containing H ₂ SiF ₆ . Then, while stirring the solution A at room temperature, the solution B and the solution C are added dropwise. A KSF phosphor can be obtained by solid-liquid separation of the obtained precipitate, washing with ethanol, and drying.

(MGF phosphor)
MGF is a red phosphor that emits deep red fluorescence. That is, the emission wavelength peak is 650 nm or more on the long wavelength side of the KSF phosphor, and the fluorophore is activated with Mn ⁴⁺ . As an example of the composition formula, it is represented by 3.5 MgO, 0.5 MgF ₂ , GeO ₂ : Mn ⁴⁺ . The half width of the MGF phosphor is 15 nm or more and 35 nm or less.

The MGF phosphor contains a part of the Mg element of MgO in its composition as Li, Na, K, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er. , Tm, Yb, Lu, V, Nb, Ta, Cr, Mo, W, etc., and some Ge elements in GeO ₂ may be replaced with other elements such as B, Al, Ga, In, etc. The emission efficiency may be improved by substituting with the element of. Preferably, by substituting both the elements Mg and Ge with both the elements Sc and Ga, respectively, the emission intensity of light in the wavelength region of 600 to 670 nm, which is called deep red, can be further improved.

The MGF fluorescent substance is a fluorescent substance represented by the following general formula (2).

(X-a) MgO · (a / 2) Sc ₂ O ₃ · yMgF ₂ · cCaF ₂ · (1-b) GeO ₂ · (b / 2) Mt ₂ O ₃ : zMn ⁴⁺ (2)
(In the formula, x, y, z, a, b, c are 2.0 ≦ x ≦ 4.0, 0 <y <1.5, 0 <z <0.05, 0 ≦ a <0.5, Satisfying 0 <b <0.5, 0 ≦ c <1.5, y + c <1.5, and Mt is at least one selected from Al, Ga, and In.)

By setting 0.05 ≦ a ≦ 0.3 and 0.05 ≦ b <0.3 in the general formula (2), the brightness of the emitted red light can be further improved. Regarding the MGF fluorescent substance, Japanese Patent Application No. 2014-11315, which the applicant of the present application filed for a patent earlier, may be referred to.

An example of a method for producing an MGF fluorescent substance according to an embodiment of the present invention will be described. First, MgO, MgF ₂ , Sc ₂ O ₃ , GeO ₂ , Ga ₂ O ₃ , and MnCO ₃ are weighed as raw materials so as to have a desired composition ratio. It can be obtained by mixing these raw materials, filling the mixed raw materials in a crucible, and firing at 1000 to 1300 ° C. in the atmosphere.

3) Green quantum dots The green quantum dots 24 are semiconductor materials, for example, compound semiconductors such as II-VI group, III-V group or IV-VI group, more specifically, CdSe, core shell type CdS _x Se ₁ . Examples thereof include nano-sized particles such as _−x / ZnS and GaP. The green quantum dots 24 have, for example, a particle size (average particle size) of 1 to 20 nm. The green quantum dot 24 emits green light having a peak emission wavelength in the range of 510 to 560 nm, for example. The half width of the emission peak of the green quantum dot 24 is as small as 40 nm or less, preferably 30 nm or less.
The green quantum dots may be surface-modified or stabilized with, for example, a resin such as PMMA (polymethyl methacrylate). In this case, the particle size means the particle size of the core portion made of a semiconductor material, which does not include a portion such as a resin attached for surface modification and stabilization.

4) Translucent material The translucent material 22 can transmit blue light, green light and red light. The translucent material transmits preferably 60% or more, more preferably 70% or more, 80% or more, or 90% or more of the light emitted from the light emitting element 1 and incident on the translucent material 22.
Preferred translucent materials 22 include high strain point glass, soda glass (Na ₂ O · CaO · SiO ₂ ), borosilicate glass (Na ₂ O · B ₂ O ₃ · SiO ₂ ), and forsterite (2 MgO · SiO ₂ ). ), Lead glass (Na ₂ O, PbO, SiO ₂ ), and non-alkali glass can be exemplified. Alternatively, polymethylmethacrylate (polymethylmethacrylate, PMMA), polyvinyl alcohol (PVA), polyvinylphenol (PVP), polyether sulfone (PES), polyimide, polycarbonate (PC), polyethylene terephthalate (PET), polystyrene (PS). , Polyethylene naphthalate (PEN), cyclic amorphous polyolefin, polyfunctional acrylate, polyfunctional polyolefin, unsaturated polyester, epoxy resin, organic polymer exemplified by silicone resin (having flexibility composed of polymer material). It has the form of a polymer material such as a plastic film, a plastic sheet, or a plastic substrate).

5) Encapsulating resin The encapsulating resin 12 can transmit blue light and red light, and preferably also can transmit green light. The translucent material transmits preferably 60% or more, more preferably 70% or more, 80% or more, or 90% or more of the light emitted from the light emitting element 1 and incident on the translucent material 22.
As the preferable sealing resin 12, a resin such as a silicone resin, a silicone-modified resin, an epoxy resin, an epoxy-modified resin, a phenol resin, a polycarbonate resin, an acrylic resin, a TPX resin, a polynorbornene resin, or a hybrid resin containing one or more of these resins. Can be mentioned. Of these, a silicone resin or an epoxy resin is preferable, and a silicone resin having excellent light resistance and heat resistance is particularly preferable.

6) Resin package The resin package 3 may be made of any kind of resin. Preferred resins include aromatic polyamide resin, polyester resin, thermoplastic resin containing at least one of liquid crystal resin, or epoxy resin, modified epoxy resin, phenol resin, silicone resin, modified silicone resin, hybrid resin, acrylate resin, and urethane. Examples thereof include resins and thermosetting resins containing at least one of these resins. The resin package 3 is preferably made of a white resin. This is because more of the light traveling inside the sealing resin 12 that has reached the resin package 3 can be reflected.

2. 2. Embodiment 2
FIG. 2 is a schematic cross-sectional view of the light emitting device 100A according to the second embodiment of the present invention. In the above-mentioned light emitting device 100, the sealing resin 12 contained the red phosphor 14. However, in the light emitting device 100A, the translucent material 22 contains the red phosphor 14 instead of the sealing resin 12 containing the red phosphor 14. Therefore, the red phosphor 14 and the green quantum dot 24 are arranged inside the translucent material 22, whereby the red phosphor 14 and the green quantum dot 24 are approximately the same distance from the light emitting element 1. Will be located in.

The light emitting device package 10A may have the same configuration as the light emitting device package 10 of the first embodiment, except that the sealing resin 12 does not contain the red phosphor 14. Further, the green quantum dot-containing layer 20A may have the same configuration as the green quantum dot-containing layer 20 of the first embodiment, except that the green quantum dot-containing layer 20A contains the red phosphor 14 in addition to the green quantum dots 24.

As described above, in the light emitting device 100 according to the first embodiment, the red phosphor 14 is located closer to the green quantum dot 24 with respect to the light emitting element 1, and the light emitting device according to the second embodiment. At 100A, the red phosphor 14 and the green quantum dot 24 are located at substantially the same distance from the light emitting element 1. Each embodiment has different advantages. The advantages will be described below.

1) Advantages of the light emitting device 100 FIG. 3 is a schematic cross-sectional view for explaining the advantages of the light emitting device 100, and in FIG. 3A, the red phosphor 14 is arranged inside the sealing resin 12. FIG. 3B is a schematic cross-sectional view showing an embodiment, and FIG. 3B is a schematic cross-sectional view showing an embodiment in which the red phosphor 14 is arranged inside the translucent material 22. As described above, the particle size of the red phosphor 14 is 20 to 50 μm, the particle size of the green quantum dots 24 is 2 to 10 nm, and there is a large difference of about two orders of magnitude in the particle size.
3A and 3B are schematic views for the purpose of more clearly showing the advantages of the light emitting device 100 based on the difference in particle size, and are red phosphors as compared with FIGS. 1 and 2. The difference in particle size between 14 and the green quantum dot 24 is shown more clearly.

Reference numeral 114 in FIG. 3A schematically shows red light (part) emitted by the red phosphor 14X, which is one of the plurality of red phosphors 14, and reference numeral 124 is a plurality of green quantum dots. The green light (part) emitted by the green quantum dot 24X, which is one of the dots 24, is schematically shown. Similarly, reference numeral 114A in FIG. 3B schematically indicates red light (part) emitted by the red phosphor 14Y, which is one of the plurality of red phosphors 14, and reference numeral 124A is a plurality. The green light (part) emitted by the green quantum dot 24Y, which is one of the green quantum dots 24 of the above, is schematically shown.

As shown in FIG. 3B, when the red phosphor 14 having a large particle size is arranged in the translucent material 22, the green light 124A emitted from the green quantum dot 24Y is red existing in the path thereof. Scattered by the phosphor 14 and does not reach the upper surface of the green quantum dot-containing layer 20A (in FIG. 3B, the red light 114A is emitted outward from the upper surface of the green quantum dot-containing layer 20A, but the green light 124A. Has not reached the upper surface of the green quantum dot-containing layer 20A). The presence of the red phosphor 14 having a large particle size in the green quantum dot-containing layer 20A causes such scattering in a part of the green light, which may cause a slight decrease in the luminous efficiency.

On the other hand, as shown in FIG. 3A, the green quantum dot-containing layer 20 does not contain the red phosphor 14 having a large particle size, and the green quantum dots 24 are removed except for the translucent material 22. Contains only. Then, it is highly unlikely that the green light traveling through the green quantum dot-containing layer 20 is scattered by the green quantum dots 24 having a very small particle size (in FIG. 3A, the red light 114 and the green light 124 are green. It protrudes outward from the upper surface of the quantum dot-containing layer 20). Therefore, higher luminous efficiency can be obtained.

2) Advantages of the light emitting device 100A The green quantum dot-containing layer 20A of the light emitting device 100A contains both the red phosphor 14 and the green quantum dot 24 as described above. Although the red phosphor 14 is less deteriorated by heat than the green quantum dots 24, it is possible to suppress the heat generation of the light emitting element 1 from being transmitted to the red phosphor 14 by adopting such a configuration. , The deterioration of the red phosphor 14 can be suppressed more reliably.
Further, since the red phosphor 14 and the green quantum dot 24 are arranged inside the translucent material 22, only the translucent material 22 needs to arrange the wavelength conversion material, and the red phosphor is placed on the sealing resin 12. Since it is not necessary to arrange the 14, the manufacturing process is simplified.

As described above, in the light emitting device 100A, the translucent material 22 of the green quantum dot-containing layer 20A contains the red phosphor 14, and the sealing resin 12 of the light emitting element package 10A does not contain the red phosphor 14. , Both the translucent material 22 of the green quantum dot-containing layer 20A and the sealing resin 12 of the light emitting element package 10A may contain the red phosphor 14.

3. 3. Embodiment 3
FIG. 4 is a schematic cross-sectional view showing a liquid crystal display 200 using the light emitting device 100B according to the third embodiment of the present invention. The light emitting device 100B includes a light emitting element package 10, a green quantum dot-containing layer 20, and a light guide plate 52 arranged between the light emitting element package 10 and the green quantum dot-containing layer 20.
In the embodiment shown in FIG. 4, the light guide plate 52 is arranged between the sealing resin 12 of the light emitting element package 10 and the green quantum dot-containing layer 20. More specifically, the sealing resin 12 is arranged to face one side surface of the light guide plate 52, and the green quantum dot-containing layer 20 is arranged to face the upper surface of the light guide plate 52. In the embodiment shown in FIG. 4, the light emitting element package 10 is of the top view type, but is not limited to this, and may have other forms such as the side view type described above.

The light emitting device 100B reflects the light that has reached the lower surface of the light guide plate 52 upward among the light incident on the light guide plate 52 from the light emitting element package 10 and directs the light toward the upper surface of the light guide plate 52. A reflector 51 may be provided on the lower surface.

In the embodiment shown in FIG. 4, the light emitting element package 10 is arranged apart from the light guide plate 52, but the present invention is not limited to this, and for example, the sealing resin 12 or the resin package 3 is attached to the light guide plate 52. The light emitting element package 10 and the light guide plate 52 may be brought into contact with each other by contacting the side surface of the light emitting element package 10 or the like.
The green quantum dot-containing layer 20 may be arranged in contact with the upper surface of the light guide plate 52, or may be arranged away from the light guide plate 52.

The lower polarizing film 53A is arranged on the green quantum dot-containing layer 20. A liquid crystal cell 54 is arranged on the lower polarizing film 53A, and a color filter array 55 is arranged on the liquid crystal cell 54. The color filter array 55 includes a plurality of types of color filters corresponding to different colors, such as the red color filter unit 55A, the green color filter unit 55B, and the blue color filter unit 55C, which transmit only light of a specific color. It has a part. An upper polarizing film 53B is arranged on the color filter array 55.

Next, a part of the blue light emitted by the light emitting element 1 for explaining the operation of the liquid crystal display 200 comes out from the sealing resin 12. Further, a part of the blue light emitted by the light emitting element 1 is absorbed by the red phosphor 14 arranged in the sealing resin 12, and the red light is emitted from the red phosphor 14, and this red light is emitted by the sealing resin 12. Come out of. That is, purple light, which is a mixture of blue light and red light, is emitted from the light emitting element package 10, and this purple light (blue light + red light) enters the green quantum dot-containing layer 20 via the light guide plate 52. .. A part of the blue light that has entered the green quantum dot-containing layer 20 is absorbed by the green quantum dots 24, and the green quantum dots 24 emit green light. As a result, white light, which is a mixture of blue light, green light, and red light, is emitted from the upper surface of the green quantum dot-containing layer 20, and the white light enters the lower polarizing film 53A. A part of the white light (blue light + green light + red light) that has entered the lower polarizing film 53A passes through the lower polarizing film 53A and enters the liquid crystal cell 54. A part of the white light entering the liquid crystal cell 54 passes through the liquid crystal cell 54 and reaches the color filter array 55.

Each of the blue light, the green light, and the red light that has reached the color filter array 55 can pass through the corresponding filter unit. For example, red light passes through the red color filter unit 55A, green light passes through the green color filter unit 55B, and blue light passes through the blue color filter unit 55C. Blue light, green light, and red light that have passed through the color filter array 55, a part of each, passes through the upper polarizing film 53B. As a result, the liquid crystal display 200 can display a desired image.
As described above, the red light emitted by the red phosphor 14 and the green light emitted by the green quantum dots 24 have a narrow half-value width of their emission peaks, and thus have high color purity. Further, since more light can pass through the red color filter unit 55A and the green color filter unit 55B, the efficiency can be improved.
The present invention includes the following aspects.

Aspect 1:
A light emitting element that emits blue light and
Quantum dots that absorb a part of the blue light emitted by the light emitting element and emit green light,
The composition is represented by the following general formula (1), and the KSF phosphor that absorbs a part of the blue light emitted by the light emitting element and emits red light and its composition are represented by the following general formula (2). At least one of the MGF phosphors that absorb a part of the blue light emitted by the light emitting element and emit red light, and
A light emitting device characterized by containing.

A ₂ [M _1-a Mn ^{4 +} _a F ₆ ] (1)
(In the formula, A is at least one selected from the group consisting of K ⁺ , Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ and NH ₄ ⁺ , and M is from Group 4 and Group 14 elements. It is at least one element selected from the group consisting of, and a is satisfied with 0 <a <0.2.)

(X-a) MgO · (a / 2) Sc ₂ O ₃ · yMgF ₂ · cCaF ₂ · (1-b) GeO ₂ · (b / 2) Mt ₂ O ₃ : zMn ⁴⁺ (2)
(In the formula, x, y, z, a, b, c are 2.0 ≦ x ≦ 4.0, 0 <y <1.5, 0 <z <0.05, 0 ≦ a <0.5, Satisfying 0 <b <0.5, 0 ≦ c <1.5, y + c <1.5, and Mt is at least one selected from Al, Ga, and In.)
Aspect 2:
The sealing resin that covers the light emitting element and
A quantum dot-containing layer containing the translucent material and the quantum dots and arranged outside the sealing resin,
The light emitting device according to aspect 1, wherein the light emitting device comprises.
Aspect 3:
The light emitting device according to aspect 2, wherein the sealing resin contains the KSF phosphor.
Aspect 4:
The light emitting device according to aspect 2 or 3, wherein the quantum dot-containing layer is a sheet and is separated from the sealing resin.
Aspect 5:
The light emitting device according to aspect 3 or 4, wherein a light guide plate is arranged between the sealing resin and the quantum dot-containing layer.
Aspect 6:
The light emitting device according to aspect 5, wherein the sealing resin is arranged so as to face one side surface of the light guide plate, and the quantum dot-containing layer is arranged so as to face the upper surface of the light guide plate. ..
Aspect 7:
The light emitting device according to aspect 2, wherein the KSF phosphor is arranged in the quantum dot-containing layer.

1 Light emitting element 3 Resin package 10, 10A Light emitting element package 12 Encapsulating resin 14 Red phosphor 20, 20A, Green quantum dot-containing layer 22 Translucent material 24, 24X, 24Y Green quantum dot 51 Reflecting plate 52 Light guide plate 53A Lower part Polarizing film 53B Upper polarizing film 54 Liquid crystal cell 55 Color filter array 55A Red color filter unit 55B Green color filter Green 55C Blue color filter unit 100, 100A, 100B Light emitting device 114, 114A Red light 124, 124A Green light 200 Liquid crystal display

Claims (8)

A light emitting element that emits blue light and
Quantum dots that absorb a part of the blue light emitted by the light emitting element and emit green light,
The composition is represented by the following general formula (1), and a KSF phosphor that absorbs a part of the blue light emitted by the light emitting element and emits red light.
The sealing resin that covers the light emitting element and
It contains a translucent material and the quantum dots, and includes a quantum dot-containing layer arranged outside the sealing resin .
The peak emission wavelength of the quantum dots is 510 to 560 nm.
A light emitting device characterized in that the KSF phosphor is arranged in the quantum dot-containing layer .

A ₂ [M _1-a Mn ^{4 +} _a F ₆ ] (1)
(In the formula, A is at least one selected from the group consisting of K ⁺ , Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ and NH ⁴⁺ , and M is from Group 4 and Group 14 elements. It is at least one element selected from the group consisting of, and a satisfies 0 <a <0.2.)
The light emitting device according to claim 1 , wherein the sealing resin contains the KSF phosphor.
The light emitting device according to claim 1 or 2 , wherein the quantum dot-containing layer is a sheet and is separated from the sealing resin.
The light emitting device according to claim 2 or 3 , wherein a light guide plate is arranged between the sealing resin and the quantum dot-containing layer.
The light emitting according to claim 4 , wherein the sealing resin is arranged so as to face one side surface of the light guide plate, and the quantum dot-containing layer is arranged so as to face the upper surface of the light guide plate. Device.
The light emitting device according to any one of claims 1 to 5 , wherein the half width of the emission peak of the KSF phosphor is 10 nm or less.
The light emitting device according to any one of claims 1 to 6 , wherein the quantum dots have a particle size of 2 to 10 nm.
The light emitting device according to any one of claims 1 to 7 , wherein the half width of the emission peak of the quantum dot is 40 nm or less.

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