JP4785363B2 - Phosphor particles, phosphor particle dispersion, and illumination device and display device including the same - Google Patents

Description

  The present invention relates to a phosphor particle that emits light upon receiving excitation light from a light-emitting element, a phosphor particle dispersion, and an illumination device and a display device including these.

  An illumination device and a display device using a phosphor that emits fluorescence due to band gap energy between ground levels formed by quantum effects in a semiconductor have been proposed (for example, see Patent Document 1).

  Specifically, the lighting device or the display device includes a light-emitting element using a nitride III-V compound semiconductor, a core particle (nuclear particle) having a particle size equal to or smaller than an exciton Bohr radius, and a shell. It is an illuminating device or a display device including a phosphor having a two-layer structure of layers (outer layers).

Further, particularly, as a light emitting device using nitride III-V compound semiconductor, which is formed on a sapphire substrate _{Ga x In 1-x N (} 0 ≦ x ≦ 1) / Ga y In 1-y An active layer having a quantum well structure composed of N (0 ≦ y ≦ 1) pairs is used. The phosphor having a two-layer structure of a core particle and a shell layer has a CdSe (core particle) / ZnS (shell layer) structure, and changes in the ground level due to quantum effects caused by changing the particle size of CdSe. A device for controlling the wavelength (color) of fluorescence using the above is shown.

However, the phosphor does not necessarily have high absorption efficiency of excitation light, and a sufficient luminance cannot be obtained in an illumination device or a display device in which the phosphor and a light emitting element are combined. Further, the phosphor has a problem of poor color rendering.
JP 11-340516 A

  In view of the above circumstances, an object of the present invention is to provide phosphor particles having high excitation light absorption efficiency and high luminance, phosphor particle dispersions excellent in color rendering, and illumination devices and display devices including these. To do.

The present invention is a phosphor particle that emits fluorescence in response to excitation light having an excitation energy E _e , from In _x1 Ga _y1 Al _1-x1-y1 N (0 <x1, 0 ≦ y1, x1 + y1 ≦ 1). and semiconductor core particles having a band gap energy E _{1 becomes, In x2 Ga y2 Al 1-} x2-y2 N (0 <x2,0 <y2, x2 + y2 ≦ 1) made from the band gap energy E ₂ that covers the semiconductor core particles includes a semiconductor shell layer having a relationship between E ₂ of E ₁ and the semiconductor shell layer of the semiconductor core particles E _e of the excitation light is E ₁ <E ₂ ≦ E _e, a semiconductor core particles in the semiconductor shell layer A discrete energy level having energy between E ₁ and E ₂ is formed in the semiconductor core particle by coating, and the phosphor particles emit fluorescence based on the energy E between the ground levels in the energy level Is

In the phosphor particles according to the present invention, the energy between the ground levels can be set in a range of 1.85 eV to 2.06 eV, 2.29 eV to 2.48 eV, or 2.58 eV to 3.02 eV. . Also, the phosphor particles according to the present invention can emit receiving excitation light from the light-emitting device comprising a semiconductor laser or a light emitting diode.

The present invention is a phosphor particle dispersion containing two or more of the above phosphor particles, including two or more phosphor particles having different ground levels, and the band gap energy E ₂ of the semiconductor shell layer of all the phosphor particles. Is a phosphor particle dispersion characterized by being larger than the energy E between the ground levels formed in the semiconductor core particles of all phosphor particles. Furthermore, the phosphor particle dispersion according to the present invention may have two or more phosphor particles dispersed in a medium.

  This invention is an illuminating device containing said fluorescent substance particle or fluorescent substance particle dispersion, and a light emitting element.

  The present invention modulates the light intensity of at least one of the phosphor particles or phosphor particle dispersion described above, a light emitting device, fluorescence emitted from the phosphor particles or phosphor particle dispersion and excitation light emitted from the light emitting device. The display device includes a light intensity modulating means.

  As described above, according to the present invention, it is possible to provide a phosphor with high excitation light absorption efficiency and high luminance, a phosphor particle dispersion excellent in color rendering, and an illumination device and a display device including these.

(Embodiment 1)
Phosphor particles according to the first embodiment of the present invention, with reference to FIG. 1, the phosphor particles 100 that emit fluorescence 13 receives the excitation light 11 with excitation energy E _e, the band gap energy E ₁ (conductivity Semiconductor core particle 101 having a band gap energy between band 101c and valence band 101v) and band gap energy E ₂ covering the semiconductor core particle (band gap energy between conduction band 102c and valence band 102v) ) and a semiconductor shell layer 102 having the relationship between E ₂ of E ₁ and the semiconductor shell layer of the semiconductor core particles E _e of the excitation light is E ₁ <E ₂ ≦ E _e, the semiconductor shell layer 102 discrete energy levels having an energy between E ₁ and E ₂ into the semiconductor core particle 101 is formed by coating the semiconductor core particles 101 Ground level 111c in energy levels, a phosphor particle emits fluorescence 13 based on the energy E between 111v.

  The reason why the phosphor particles of the present embodiment have high excitation light absorption efficiency and high luminance will be specifically described in comparison with conventional phosphor particles.

For example, referring to FIG. 2, conventional phosphor particles are coated with CdSe core particles having a band gap energy E ₁ of about 1.7 eV and a diameter of about ₆ to 10 nm as semiconductor core particles 201, and semiconductor core particles 201. The semiconductor shell layer 202 to be formed is a ZnS shell layer having a band gap energy E ₂ of 3.80 eV, and the excitation energy E _e emitted from the In _x3 Ga _1-x3 N (0 ≦ x3 ≦ 1) light emitting element is 2. The phosphor particles emit fluorescence 13 in response to the excitation light 11 of 88 eV (wavelength 430 nm). A part of the excitation light is scattered by the phosphor particle surface and reflected as scattered light 12.

  In this conventional phosphor particle, the energy E between the ground levels 211c and 211v formed in the CdSe core particle by covering the CdSe core particle with the ZnS shell layer is, for example, 1.9 eV (650 nm), and the wavelength Emits fluorescence 13 at 650 nm. In FIG. 2B, C.I. B is the conduction band; B represents a valence band, white circles represent electrons 14, and black circles represent holes 15.

As described above, in the conventional phosphor particles, the relationship between E _e , E ₂ and E is E <E _e <E ₂ , and in such a band structure, the energy formed in the CdSe core particles The energy state density capable of absorbing the excitation light 11 having the level, that is, the excitation energy E _e exists only discretely, and if it deviates even a little from this energy level, the absorption efficiency of the excitation light is lowered and the luminance is lowered. In the In _x3 Ga _1-x3 N light emitting device (0 ≦ x3 ≦ 1), the excitation energy E _e is 3.38 eV or less regardless of how the composition of In and Ga is changed. E _e <E ₂

In contrast, the phosphor particles according to the present embodiment include, for example, an InN core particle having a band gap energy E ₁ of 2.00 eV (wavelength 620 nm) as a semiconductor core particle 101 and a semiconductor core particle with reference to FIG. The semiconductor shell layer 102 covering 101 includes an In _x2 Ga _1-x2 N shell layer (0 <x2 <1) having a band gap energy E ₂ of 2.80 eV (wavelength 442 nm), and In _x3 Ga _1-x3 The phosphor particles emit fluorescence 13 upon receiving excitation light 11 having an excitation energy E _e of 2.88 eV (430 nm) emitted from an N light emitting element (0 ≦ x3 ≦ 1). A part of the excitation light is scattered by the phosphor particle surface and reflected as scattered light 12.

In the phosphor particles of this embodiment, the InN core particles are covered with an In _x2 Ga _1-x2 N shell layer (0 <x2 <1), whereby ground levels 111c and 111v formed in the InN core particles are formed. The energy E between them is, for example, 2.58 eV (wavelength 480 nm), and emits fluorescence 13 having a wavelength of 480 nm.

As described above, In _x2 Ga _1-x2 N shell layer is a semiconductor shell layers as (0 <x2 <1) E 2 is less than or equal to E _e of the excitation light, In _x2 Ga _1-x2 N shell layer By setting the elemental composition ratio x2, most of the excitation light can be absorbed by the semiconductor shell layer. Thereby, the volume (volume of a semiconductor shell layer) which can absorb excitation light can be increased, and the brightness | luminance of fluorescent substance particle becomes high.

  The present embodiment is an example of phosphor particles that emit blue fluorescence whose energy E between ground levels formed in the semiconductor core particles is 2.58 eV (wavelength 480 nm). In addition, by adjusting the constituent element or element composition ratio of the semiconductor core particle or the semiconductor shell layer, the energy between the ground levels emits red fluorescence having a wavelength of 1.85 eV to 2.06 eV (wavelength 670 nm to 600 nm). Phosphor particles, phosphor particles emitting green fluorescence of 2.29 eV to 2.48 eV (wavelength 540 nm to 500 nm), phosphor particles emitting blue fluorescence of 2.58 eV to 3.02 eV (wavelength 480 nm to 410 nm) Obtainable.

In the present embodiment, InN core particles made of InN are used as the semiconductor core particles. However, as the semiconductor constituting the semiconductor core particles, In _x1 Ga _y1 Al _1-x1-y1 N (0 < _x1, 0 ≦ y1) _X1 + _y1≤1 ), _{Cdz11Zn1 -z11Se} (0 <z11≤1), _{Cdz12Zn1 -z12S} (0 <z12≤1), etc. are also preferably used.

In the present embodiment, an In _x2 Ga _1-x2 N shell layer (0 <x2 <1) is used as the semiconductor shell layer, but In _x2 Ga _y2 Al _1-x2-y2 N (0 < _x2, 0 <y2 X2 + y2 ≦ 1) or Cd _y21 Zn _1-y21 Se (0 ≦ y21 <1) is also preferably used.

Here, the elemental composition ratio of the semiconductor core particles and semiconductor shell layers x1, y1, z11, z12, x2, y2, z21 is the E ₂ of E ₁ and the semiconductor shell layer of the semiconductor core particles E _e of the excitation light E ₁ and E ₂ are set so that the relationship E ₁ <E ₂ ≦ E _e is obtained. The particle size of the semiconductor core particles, by the E ₂ of E ₁ and the semiconductor shell layer of the semiconductor core particles are set as desired E is obtained.

  The light emitting element used in the present embodiment is not particularly limited, but a semiconductor laser or a light emitting diode is preferable from the point that excitation light having stable energy (wavelength) can be obtained.

  The method for producing the phosphor particles of the present embodiment is not particularly limited, but a chemical synthesis in which a plurality of starting materials containing the constituent elements of the product substance are dispersed in a medium and reacted to obtain a target product substance. The method is preferable because it is a simple method and low cost. Chemical synthesis methods include sol-gel method (colloid method), reverse micelle method, molecular precursor method, hydrothermal synthesis method, flux method and the like.

(Embodiment 2)
A phosphor particle dispersion according to Embodiment 2 of the present invention is a phosphor particle dispersion including two or more of the phosphor particles, and the phosphor particle dispersion includes two or more phosphor particles having different ground levels. A phosphor particle dispersion in which the band gap energy E ₂ of the semiconductor shell layer of all phosphor particles is larger than the energy E between the ground levels formed in the semiconductor core particles of all phosphor particles. is there.

More specifically, referring to FIG. 3, fluorescence in which two or more phosphor particles having different ground levels are dispersed in a transparent epoxy resin as medium 3100 as shown in FIG. In the body particle dispersion 3000, the band gap energy E ₂ of the semiconductor shell layer of all the phosphor particles is larger than the energy E between the ground levels formed in the semiconductor core particles of all the phosphor particles. The phosphor particle dispersion will be described.

  Since the phosphor particles emit fluorescence of different colors depending on the difference in energy E between the ground levels, for example, blue phosphor particles that emit blue fluorescence, green phosphor particles that emit green fluorescence, and / or The chromaticity of the fluorescent color can be adjusted by dispersing red phosphor particles emitting red fluorescence in the medium at a predetermined ratio.

  For example, with reference to FIG. 3 and FIG. 4, the interaction between the blue phosphor particles 100 and the red phosphor particles 300 in the phosphor particle dispersion 3000 will be described.

The blue phosphor particle 100 has an InN core particle having a band gap energy E _1B of 2.00 eV (wavelength 620 nm) as the semiconductor core particle 101 and 2.82 eV (wavelength as the semiconductor shell layer 102 covering the semiconductor core particle 101). 440 nm) of In _x21 Ga _1-x21 N shell layer (0 <x21 <1) having a band gap energy E _2B and excited by an In _x3 Ga _1-x3 N light emitting device (0 ≦ x3 ≦ 1) The phosphor particles emit fluorescence 13 upon receiving excitation light 11 having energy E _e of 2.88 eV (430 nm). In the blue phosphor particles in the present embodiment, the ground levels 111c and 111v formed in the InN core particles by covering the InN core particles with an In _x21 Ga _{1 -x21} N shell layer (0 <x21 <1). energy E _B between emits 2.58 eV (wavelength 480 nm), and the fluorescence 13 of the blue wavelength 480 nm.

The red phosphor particles 300 have InN core particles having a band gap energy E _1R of 2.00 eV (wavelength 620 nm) as the semiconductor core particles 301 and 2.76 eV as the semiconductor shell layer 302 covering the semiconductor core particles 301. It _consists of an In _x22 Ga _{1 -x22} N shell layer (0 <x22 <1) having a band gap energy E _2R (wavelength 450 nm), and an In _x3 Ga _1-x3 N light emitting device (0 ≦ x3 ≦ 1) is emitted. The phosphor particles emit fluorescence 13 upon receiving excitation light 11 having an excitation energy E _e of 2.88 eV (430 nm). In the red phosphor particles in the present embodiment, ground levels 311c and 311v formed in the InN core particles by covering the InN core particles with an In _x22 Ga _1-x22 N shell layer (0 <x22 <1). energy between E _R emits 2.03EV (wavelength 610 nm), and the fluorescence 13 of the red wavelength 610 nm.

  That is, when excitation light having excitation energy of 2.88 eV (wavelength 430 nm) is irradiated onto the phosphor particle dispersion, the excitation light is absorbed by each of the blue phosphor particles 100 and the red phosphor particles 300. And emits blue fluorescence having a wavelength of 480 nm and red fluorescence having a wavelength of 610 nm, respectively.

As described above, in the blue phosphor particles and the red phosphor particles, the E _2B and E _2R of the semiconductor shell layer of any phosphor particle are used as the base level formed on the semiconductor core particle of any phosphor particle. By making the interstitial energy E _B or E _R larger than the blue fluorescent particles, it is possible to suppress the blue fluorescent particles from being reabsorbed by the red fluorescent particles. Can maintain good chromaticity.

  In the above description, the relationship between the blue phosphor particles and the red phosphor particles is described. However, the relationship between the blue phosphor particles and the green phosphor particles and the relationship between the green phosphor particles and the red phosphor particles. The same applies to.

That is, in the phosphor particle dispersion including two or more phosphor particles having different ground levels, the band gap energy E ₂ of the semiconductor shell layer of all phosphor particles is in the semiconductor core particles of all phosphor particles. By designing the phosphor particles so as to be larger than the energy E between the ground levels formed in the phosphor particles, a phosphor particle dispersion having excellent chromaticity of fluorescence of each phosphor particle and excellent color rendering properties can be obtained. can get.

  By the way, the optical characteristics of fluorescence when a plurality of phosphor particles are dispersed as described above will be described below.

  In FIG. 3B, the blue phosphor particles 100 and the red phosphor particles 300 are respectively irradiated with the excitation light 11, and the fluorescence 13 based on the energy between the ground levels according to the particle size of the semiconductor core particles. 33 and the scattered light 12 and 32 in which the excitation light 13 is scattered by the phosphor particle surface are also shown.

The scattering state of the phosphor particles with respect to the excitation light in such phosphor particles or the fluorescence emitted from other phosphor particles is expressed as follows: I (θ) = | Σ ( 2ν + 1) / ν (ν + 1) {a _ν Π _ν (cosθ) + b _ν τ _ν (cosθ)} | ²
ν = 1, ∞
It is represented by Here, a _ν and b _ν are coefficients representing complex amplitudes, which are functions of the refractive index of the particles and the size factor (particle size). Further, _{ν ν} and τ _ν are functions of only the scattering angle, and are a Legendre polynomial and its derivatives.

  For this reason, when the particle diameters of the phosphor particles that develop each color are different, the scattering state of the fluorescence emitted from the excitation light and other phosphor particles is different for each type of phosphor particles.

  At this time, in order to adjust the scattering state of the fluorescence, as shown in FIG. 5, if the phosphor particles 100 and 300 are adjusted only by the thickness of the semiconductor shell layers 102 and 302, the semiconductor shell that absorbs excitation light is used. The volumes of the layers 102 and 302 are different, which causes a problem that the absorption coefficient for the excitation light is different for each phosphor particle.

In order to adjust the magnitude of the energy E between the ground levels formed in the semiconductor core particle in order to solve this problem, not only the thickness of the semiconductor shell layers 102 and 302 but also the semiconductor core particle and / or The constituent element species and composition ratio of the semiconductor shell layer are adjusted. That is, in the present embodiment, the band gap energy E ₂ of the semiconductor shell layers of all the phosphor particles contained in the phosphor particle dispersion is changed to the ground level formed in the semiconductor core particles of all the phosphor particles. The constituent element species and / or composition ratio of the semiconductor core particles and / or the semiconductor shell layer are adjusted so as to be larger than the energy E between them.

(Embodiment 3)
The illumination device according to Embodiment 3 of the present invention is an In _x4 Ga _1-x4 N light emitting diode (0 ≦ x4 ≦ 1) that emits excitation light having an excitation energy of 2.88 eV (wavelength 430 nm) with reference to FIG. Fluorescence in which two or more blue phosphor particles, green phosphor particles, and red phosphor particles are dispersed in a transparent epoxy resin as a medium on top of a lead frame 601 on which a chip (not shown) is mounted. It is the illuminating device 600 in which the body particle dispersion 602 was formed. Here, the band gap energy E ₂ of the semiconductor shell layers of all the phosphor particles contained in the phosphor particle dispersion 602 is determined between the ground levels formed in the semiconductor core particles of all the phosphor particles. Since all the phosphor particles are designed so as to be larger than the energy E, a white illumination device having excellent color rendering properties is obtained by the color mixture of the fluorescence of each phosphor particle. In addition, it can also be set as a planar illuminating device by arranging the said point-shaped illuminating device in an array form.

(Embodiment 4)
Lighting device according to a fourth embodiment of the present invention, with reference to FIG. 7, as shown in FIG. _{7 (a), In x5 Ga} 1-x5 excitation energy oscillates excitation light of 2.88 eV (wavelength 430 nm) A stem 701 on which a chip (not shown) of an N semiconductor laser (0 ≦ x5 ≦ 1) is mounted is an illumination device 700 that is optically coupled to a light guide 708 via a resin 707.

Here, referring to FIG. 7A and FIG. 7B, in the light guide 708, a core 702 made of acrylic is covered with a clad 704 made of a fluororesin having a refractive index lower than that of the core. It has a structure. Further, an In _x5 Ga _{1 -x5} N semiconductor laser is formed on one end face of the light guide 708, and a reflection film 706 made of, for example, silicon oxide that reflects excitation light propagating through the light guide is formed on the other end face. Has been. Further, a scatterer 703 made of TiO ₂ particles is provided on a part of the core 702, and excitation light incident on the light guide 708 from the semiconductor laser is diffused around by the scatterer 703. Instead of using the scatterer made of TiO ₂ particles, an uneven portion (not shown) is provided at the interface between the core 702 and the clad 704, and irregular reflection at the interface having the uneven portion may be used. Good. Further, a phosphor particle dispersion 705 in which two or more blue phosphor particles, green phosphor particles, and red phosphor particles are dispersed in a transparent epoxy resin as a medium is formed on the outer periphery of the light guide 708. Thus, the phosphor layer 709 of the lighting device 700 is obtained.

  With the above configuration, an illuminating device that emits linear white fluorescent light 710 excellent in color rendering is obtained. An illumination device having a desired chromaticity other than white by appropriately changing the mixing ratio of the blue phosphor particles, the green phosphor particles, and / or the red phosphor particles in the phosphor particle dispersion. realizable.

  Note that the dotted or linear illumination device shown in Embodiment 3 or Embodiment 4 can also be used for illumination as a lighting device in a general home, and further as a liquid crystal backlight or a light source of a liquid crystal projector.

(Embodiment 5)
In the display device according to the fifth embodiment of the present invention, referring to FIG. 8, a stem 701 on which a chip (not shown) of an In _x5 Ga _1-x5 N semiconductor laser (0 ≦ x5 ≦ 1) is mounted is guided. The light guide body 811 is optically coupled to another light guide body 801, and an upper surface portion of the light guide body 801 is provided with a light modulation element 802 for modulating light intensity. Thus, an element (specifically, a blue phosphor particle-containing resin 803, a green phosphor particle-containing resin 804, and a red phosphor particle-containing resin 805) including phosphor particles or phosphor particle dispersions of respective colors is formed. This is a display device 800.

Here, in the light guide 811, a core 702 made of acrylic is covered with a clad 704 made of a fluorine-based resin having a refractive index lower than that of the core, and the clad 704 is a reflective film 812 made of a metal Al film having an opening 811 a. It has a structure covered with. A scatterer 703 made of TiO ₂ particles is formed on a part of the core 702. Further, the one end surface of the light guide _{811, In x5 Ga 1-x5} N stem 701 for mounting the semiconductor laser is disposed on the other end face, the light of the In _x5 Ga _1-x5 N semiconductor laser A reflective film 706 made of, for example, silicon oxide is formed. With this configuration, excitation light emitted from a semiconductor laser that is a point light source is converted into a linear light source.

  The light guide 811 is optically coupled to another light guide 801, and linear excitation light radiated from the opening 811 a of the light guide 811 is incident on the light guide 801. The Further, a reflective film 806 made of a metal Al film is formed on the lower surface (rear surface) side of the light guide 801, and linear excitation light propagates through the light guide 801 and is linearly excited. A part of the light is emitted in the upper surface direction by the reflective film 806. With this configuration, a linear light source is converted into a planar light source.

  On the upper surface of the light guide 801, a liquid crystal light modulation element including an active matrix driving type TFT (thin film transistor) sandwiched between polarizing plates so as to control the light intensity of the excitation light emitted as the light modulation element 802 is provided. The light intensity is modulated by the liquid crystal light modulation element.

  On the upper surface of the light modulation element 802, a phosphor particle-containing element (blue phosphor particle-containing resin 803) in which phosphor particles of each color are dispersed in a transparent epoxy resin, which is a medium, corresponding to each pixel on the light modulation element. , Green phosphor particle-containing resin 804, red phosphor particle-containing resin 805). Therefore, a desired image is displayed by irradiating the blue phosphor particle-containing resin 803, the green phosphor particle-containing resin 804, and the red phosphor particle-containing resin 805 with the excitation light whose light intensity is modulated. be able to. In this way, a display device excellent in color rendering is obtained. In addition, as a means for controlling the light intensity of the fluorescence emitted from the phosphor, a means for absorbing the fluorescence emitted from the phosphor by the optical electric field absorption effect can be used.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  As described above, the present invention can be widely used for phosphor particles with high excitation light absorption efficiency and high luminance, phosphor particle dispersions excellent in color rendering, and illumination devices and display devices including these.

(A) is a cross-sectional schematic diagram of the phosphor particles according to Embodiment 1 of the present invention. FIG. 2B is a band structure diagram of phosphor particles according to Embodiment 1 of the present invention. (A) is a cross-sectional schematic diagram of conventional phosphor particles. (B) is the band structure figure of the conventional fluorescent substance particle. (A) is a three-dimensional perspective schematic diagram of the phosphor particle dispersion according to Embodiment 2 of the present invention. (B) is an expanded cross-sectional schematic diagram of two fluorescent substance particles in the fluorescent substance particle dispersion by Embodiment 2 of this invention. It is a band structure figure of two fluorescent substance particles in the fluorescent substance particle dispersion by Embodiment 2 of the present invention. It is a cross-sectional schematic diagram explaining adjustment of the thickness of a semiconductor shell layer about two fluorescent substance particles in a fluorescent substance particle dispersion. It is a three-dimensional schematic diagram of the illuminating device by Embodiment 3 of this invention. (A) is a three-dimensional schematic diagram of the illuminating device by Embodiment 4 of this invention. (B) It is a cross-sectional schematic diagram from the VII direction of the illuminating device by Embodiment 4 of this invention. (A) It is a three-dimensional schematic diagram of the display apparatus by Embodiment 5 of this invention. (B) It is a cross-sectional schematic diagram from the VIII direction of the light guide used for the display apparatus by Embodiment 5 of this invention.

Explanation of symbols

  11 excitation light, 12, 22, 32 scattered light, 13, 23, 33 fluorescence, 14 electrons, 15 holes, 100, 200, 300 phosphor particles, 101, 201, 301 semiconductor core particles, 101c, 102c, 201c, 202c, 301c, 302c conduction band, 101v, 102v, 201v, 202v, 301v, 302v valence band, 102, 202, 302 semiconductor shell layer, 111c, 111v, 211c, 211v, 311c, 311v ground level, 600, 700 Illumination device, 602, 705, 3000 phosphor particle dispersion, 701 stem, 702 core, 703 scatterer, 704 clad, 706, 806, 812 reflective film, 707 resin, 708, 801, 811 light guide, 709 phosphor Layer, 710 white fluorescence, 800 display, 80 2 Light modulation element, 803 Blue phosphor particle-containing resin, 804 Green phosphor particle-containing resin, 805 Red phosphor particle-containing resin, 811a opening, 3100 medium.

Claims (7)

Phosphor particles that emit fluorescence in response to excitation light having excitation energy E _e ,
In _x1 Ga _y1 Al _1-x1-y1 N (0 <x1, 0 ≦ y1, x1 + y1 ≦ 1), semiconductor core particles having band gap energy E _1, and In _x2 Ga _y2 Al covering the semiconductor core particles Comprising a semiconductor shell layer composed of _1-x2-y2 N (0 <x2, 0 <y2, x2 + y2 ≦ 1) and having a band gap energy E ₂ ;
The relationship between E _{1 of the} semiconductor core particles, E _{2 of the} semiconductor shell layer, and E _{e of the} excitation light is E ₁ <E ₂ ≦ E _e ,
By covering the semiconductor core particle with the semiconductor shell layer, a discrete energy level having energy between E ₁ and E ₂ is formed in the semiconductor core particle, and a ground level in the energy level is formed. Phosphor particles emitting fluorescence based on the energy E between them.   The phosphor particles according to claim 1, wherein the energy between the ground levels is in a range of 1.85 eV to 2.06 eV, 2.29 eV to 2.48 eV, or 2.58 eV to 3.02 eV. The phosphor particles according to claim 1 , wherein the phosphor particles emit light upon receiving excitation light from a light emitting element comprising a semiconductor laser or a light emitting diode. A phosphor particle dispersion comprising two or more phosphor particles according to any one of claims 1 to 3 ,
The base includes two or more phosphor particles having different ground levels, and the band gap energy E ₂ of the semiconductor shell layer of all the phosphor particles is formed in the semiconductor core particles of all the phosphor particles. A phosphor particle dispersion characterized by being larger than energy E between levels. The phosphor particle dispersion according to claim 4 , wherein the two or more phosphor particles are dispersed in a medium. Lighting device comprising a phosphor particles or phosphor particle dispersion according, and a light emitting element in any of claims 1 to 5. The phosphor particles or phosphor particle dispersion according to any one of claims 1 to 5 , a light emitting element, fluorescence emitted from the phosphor particles or phosphor particle dispersion, and excitation light emitted from the light emitting element. A display device comprising light intensity modulation means for modulating the light intensity of at least one light.

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