JP2011252117A - Semiconductor microparticle phosphor and wavelength conversion member using it, light-emitting device, and image display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor microparticle phosphor having high light-emitting efficiency and a wavelength conversion member, light-emitting device and an image display each using the phosphor.SOLUTION: This semiconductor microparticle phosphor has a semiconductor crystal core and a shell layer covering the semiconductor crystal core; satisfies following general formula (1): Ec'<Ec(shell) and general formula (2): Ev'>Ev(shell) [wherein Ec(shell) indicates an energy level at the lower end of a conduction band of the shell layer; Ev(shell) indicates an energy level at the upper end of a valence band of the shell layer; Ec' indicates a quantum level formed by the confinement effect of electrons in the inside of the semiconductor microparticle phosphor; and Ev' indicates a quantum level formed by the confinement effect of holes in the inside of the semiconductor microparticle phosphor]. The semiconductor crystal core comprises InN, and the shell layer comprises at least either compound semiconductor of GaN and AlN.

Description

  The present invention relates to a semiconductor fine particle phosphor, a wavelength conversion member, a light emitting device, and an image display device using the semiconductor fine particle phosphor.

  Until now, rare earth activated phosphors have been widely used in the lighting field. However, in recent years, semiconductor fine particle phosphors have attracted attention in place of rare earth activated phosphors. The semiconductor fine particle phosphor has a feature that the emission wavelength can be arbitrarily controlled, which was not found in the rare earth activated phosphor. For this reason, the light emitting device using the semiconductor fine particle phosphor can realize various emission spectra. The semiconductor fine particle phosphor is expected as a technique that enables the production of an efficient light-emitting device with high color rendering properties.

  In order to put the semiconductor fine particle phosphor into practical use, it is indispensable to improve the light emission efficiency, and studies are currently underway to improve the efficiency.

  For example, Patent Document 1 (International Publication No. 2007/086267) discloses a semiconductor having a core / shell structure in which a semiconductor core particle as a light emitting portion is covered with a semiconductor shell material in order to improve luminous efficiency. A fine particle phosphor has been proposed. In Patent Document 1, a semiconductor fine particle phosphor with high emission efficiency is synthesized by using a semiconductor shell material having a larger band gap than the semiconductor core material forming the semiconductor core particles.

International Publication No. 2007/086267

  However, the technology for increasing the efficiency of the semiconductor fine particle phosphor described in Patent Document 1 only describes “making the band gap larger than the semiconductor core material” as the condition of the semiconductor shell material. The semiconductor fine particle phosphor synthesized based on such conditions has a problem that the luminous efficiency is not sufficiently high from the viewpoint of practical use.

  The present invention has been made in view of the above situation, and its object is to provide a semiconductor fine particle phosphor having high luminous efficiency, and a wavelength conversion member, a light emitting device, and an image display device using the same. Is to provide.

The present invention is a semiconductor fine particle phosphor having a semiconductor crystal core and a shell layer covering the semiconductor crystal core, satisfying the following general formulas (1) and (2):
Ec ′ <Ec (shell) (1)
Ev ′> Ev (shell) (2)
(In the formula, Ec (shell) indicates the energy level at the lower end of the conduction band of the shell layer, Ev (shell) indicates the energy level at the upper end of the valence band of the shell layer, and Ec ′ indicates the inside of the semiconductor fine particle phosphor. Ev ′ represents the quantum level formed by the confinement effect of holes inside the semiconductor fine particle phosphor.
A semiconductor fine particle phosphor in which a semiconductor crystal core is made of InN and a shell layer is made of a compound semiconductor of at least one of GaN and AlN.

  In the semiconductor fine particle phosphor according to the present invention, preferably, the shell layer is made of GaN, and the thickness of the shell layer is 1.1 nm or more.

  In the semiconductor fine particle phosphor according to the present invention, preferably, the shell layer is made of AlN, and the thickness of the shell layer is 0.4 nm or more.

The present invention is a semiconductor fine particle phosphor having a semiconductor crystal core and a shell layer covering the semiconductor crystal core, satisfying the following general formulas (1) and (2):
Ec ′ <Ec (shell) (1)
Ev ′> Ev (shell) (2)
(In the formula, Ec (shell) indicates the energy level at the lower end of the conduction band of the shell layer, Ev (shell) indicates the energy level at the upper end of the valence band of the shell layer, and Ec ′ indicates the inside of the semiconductor fine particle phosphor. Ev ′ represents the quantum level formed by the confinement effect of holes inside the semiconductor fine particle phosphor.
A semiconductor fine particle phosphor in which a semiconductor crystal core is made of InN and a shell layer is made of at least one compound semiconductor selected from the group consisting of ZnO, MgO and MgS.

The present invention is a semiconductor fine particle phosphor having a semiconductor crystal core and a shell layer covering the semiconductor crystal core, satisfying the following general formulas (1) and (2):
Ec ′ <Ec (shell) (1)
Ev ′> Ev (shell) (2)
(In the formula, Ec (shell) indicates the energy level at the lower end of the conduction band of the shell layer, Ev (shell) indicates the energy level at the upper end of the valence band of the shell layer, and Ec ′ indicates the inside of the semiconductor fine particle phosphor. Ev ′ represents the quantum level formed by the confinement effect of holes inside the semiconductor fine particle phosphor.
A semiconductor fine particle phosphor in which a semiconductor crystal core is made of InP and a shell layer is made of at least one compound semiconductor selected from the group consisting of ZnS, ZnSe, and AlP.

  In the semiconductor fine particle phosphor according to the present invention, preferably, the shell layer is ZnS, and the thickness of the shell layer is 0.9 nm or more.

  In the semiconductor fine particle phosphor according to the present invention, preferably, the shell layer is ZnSe and the thickness of the shell layer is 1.3 nm or more.

  In the semiconductor fine particle phosphor according to the present invention, the shell layer is preferably AlP, and the thickness of the shell layer is 3.4 nm or more.

The present invention is a semiconductor fine particle phosphor having a semiconductor crystal core and a shell layer covering the semiconductor crystal core, satisfying the following general formulas (1) and (2):
Ec ′ <Ec (shell) (1)
Ev ′> Ev (shell) (2)
(In the formula, Ec (shell) indicates the energy level at the lower end of the conduction band of the shell layer, Ev (shell) indicates the energy level at the upper end of the valence band of the shell layer, and Ec ′ indicates the inside of the semiconductor fine particle phosphor. Ev ′ represents the quantum level formed by the confinement effect of holes inside the semiconductor fine particle phosphor.
A semiconductor fine particle phosphor in which the semiconductor crystal core is made of InP and the shell layer is made of at least one compound semiconductor selected from the group consisting of AlN, MgO, MgS, MgSe, 3C—SiC, and 6H—SiC.

The present invention is a semiconductor fine particle phosphor having a semiconductor crystal core and a shell layer covering the semiconductor crystal core, satisfying the following general formulas (1) and (2):
Ec ′ <Ec (shell) (1)
Ev ′> Ev (shell) (2)
(In the formula, Ec (shell) indicates the energy level at the lower end of the conduction band of the shell layer, Ev (shell) indicates the energy level at the upper end of the valence band of the shell layer, and Ec ′ indicates the inside of the semiconductor fine particle phosphor. Ev ′ represents the quantum level formed by the confinement effect of holes inside the semiconductor fine particle phosphor.
The semiconductor crystal core is made of CdSe,
It is a semiconductor fine particle phosphor whose shell layer is made of ZnS.

  In the semiconductor fine particle phosphor according to the present invention, the thickness of the shell layer is preferably 1.0 nm or more.

The present invention is a semiconductor fine particle phosphor having a semiconductor crystal core and a shell layer covering the semiconductor crystal core, satisfying the following general formulas (1) and (2):
Ec ′ <Ec (shell) (1)
Ev ′> Ev (shell) (2)
(In the formula, Ec (shell) indicates the energy level at the lower end of the conduction band of the shell layer, Ev (shell) indicates the energy level at the upper end of the valence band of the shell layer, and Ec ′ indicates the inside of the semiconductor fine particle phosphor. Ev ′ represents the quantum level formed by the confinement effect of holes inside the semiconductor fine particle phosphor.
The semiconductor crystal core is made of CdSe,
It is a semiconductor fine particle phosphor in which the shell layer is made of at least one compound semiconductor selected from the group consisting of AlN, AlP, GaN, ZnSe, MgO, MgS, MgSe, and 6H—SiC.

  In the semiconductor fine particle phosphor according to the present invention, the lattice mismatch rate between the semiconductor crystal core and the shell layer is preferably 15% or less.

  In the semiconductor fine particle phosphor according to the present invention, preferably, the semiconductor crystal core is made of a direct transition type compound semiconductor.

  The semiconductor fine particle phosphor according to the present invention preferably emits visible light of 380 nm to 780 nm.

  In the semiconductor fine particle phosphor according to the present invention, the average particle diameter of the semiconductor crystal core is preferably not more than twice the Bohr radius.

  The present invention is a wavelength conversion member comprising the semiconductor fine particle phosphor according to the present invention and a translucent member.

  The present invention is a light emitting device including the semiconductor fine particle phosphor according to the present invention and a light emitting element.

  In the light emitting device according to the present invention, the light emitting element is preferably a semiconductor light emitting diode element or a semiconductor light emitting laser diode element.

  The light emitting device according to the present invention preferably contains two or more kinds of semiconductor fine particle phosphors.

  In the light emitting device according to the present invention, preferably, the semiconductor light emitting element emits blue light, and the semiconductor fine particle phosphor contains at least a green light emitting semiconductor fine particle phosphor and a red light emitting semiconductor fine particle phosphor.

  The present invention is an image display device comprising the semiconductor fine particle phosphor according to the present invention and a light emitting element.

  The image display according to the present invention preferably contains two or three kinds of semiconductor fine particle phosphors.

  In the image display according to the present invention, the light emitting element is preferably a semiconductor light emitting diode element, a semiconductor light emitting laser diode element, or an organic electroluminescence element.

  In the image display according to the present invention, preferably, the semiconductor light emitting element emits blue light, and the semiconductor fine particle phosphor contains at least a green light emitting semiconductor fine particle phosphor and a red light emitting semiconductor fine particle phosphor.

  According to the present invention, a semiconductor fine particle phosphor having high luminous efficiency can be provided. Furthermore, by using the semiconductor fine particle phosphor, it is possible to provide a wavelength conversion member and a light emitting device excellent in luminous efficiency, and an image display device excellent in screen luminance.

1 is a schematic cross-sectional view showing a semiconductor fine particle phosphor having a core / shell structure in an embodiment of the present invention. 1 is a schematic cross-sectional view showing a semiconductor fine particle phosphor having a core / multishell structure in one embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a semiconductor fine particle phosphor according to an embodiment of the present invention, and an energy band structure of the semiconductor fine particle phosphor and the existence probability of electrons and holes. FIG. 2 is a schematic cross-sectional view showing a semiconductor fine particle phosphor described in Patent Document 1, and an energy band structure of the semiconductor fine particle phosphor and a probability of existence of electrons and holes. It is typical sectional drawing which shows the wavelength conversion member in one embodiment of this invention. It is typical sectional drawing which shows the light-emitting device in one embodiment of this invention. 1 is a schematic exploded perspective view showing an image display device in an embodiment of the present invention. It is a typical exploded perspective view showing a liquid crystal part of an image display device in one embodiment of the present invention. It is a graph which shows the transmission spectrum of the color filter of the image display apparatus in one embodiment of this invention. It is a graph which shows the relationship between the film thickness of the shell layer of Example 6, and luminous efficiency.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts.

<Semiconductor fine particle phosphor>
In the present invention, the semiconductor fine particle phosphor refers to a substance having a function of absorbing at least a part of excitation light and emitting light having a wavelength different from that of the excitation light. In one embodiment of the present invention, in the semiconductor fine particle phosphor, the semiconductor crystal core that is the light emitting portion is made of a semiconductor microcrystal having a particle diameter of about several nanometers. Such semiconductor microcrystals are sometimes referred to as colloidal particles, nanoparticles, quantum dots, or the like. Hereinafter, the semiconductor fine particle phosphor in the present invention will be described.

(1) Structure of semiconductor fine particle phosphor In one embodiment of the present invention, the semiconductor fine particle phosphor has a core / shell structure having a semiconductor crystal core and one shell layer covering the semiconductor crystal core. be able to. Further, it may have a core / multishell structure having a semiconductor crystal core and a plurality of shell layers covering the semiconductor crystal core.

  FIG. 1 is a schematic cross-sectional view showing a semiconductor fine particle phosphor 100 having a core / shell structure according to an embodiment of the present invention. In the semiconductor fine particle phosphor 100, at least a part of the surface of the semiconductor crystal core 101 made of a semiconductor material is covered with the shell layer 102. Further, the modified organic compound 103 may be bonded to the surface of the shell layer 102.

  FIG. 2 is a schematic cross-sectional view showing a semiconductor fine particle phosphor 200 having a core / multishell structure in one embodiment of the present invention. In the semiconductor fine particle phosphor 200, the shell layer 202 covering the semiconductor crystal core 201 is covered with another shell layer 203.

  Any known method can be used as the method for examining the structure of the semiconductor fine particle phosphor. For example, it can be performed by direct observation using a transmission electron microscope (TEM).

(1a) Semiconductor Crystal Core In one embodiment of the present invention, the semiconductor crystal core has a function of emitting light when electrons and holes generated when absorbing excitation light are recombined. The emission wavelength of the conventional rare earth-activated phosphor is a constant value unique to the material constituting the phosphor. However, in the semiconductor fine particle phosphor, the emission wavelength can be arbitrarily controlled by changing the particle diameter of the semiconductor crystal core. This is because a quantum confinement effect occurs when the particle size of the semiconductor crystal core is reduced to twice or less the Bohr radius. Here, Bohr radii of InP, InN, and CdSe, which are examples of semiconductor crystal core materials, are 8.3 nm, 7.0 nm, and 4.9 nm, respectively.

(1b) Shell Layer In one embodiment of the present invention, the shell layer is made of a material different from that of the semiconductor crystal core and covers at least a part of the surface of the semiconductor crystal core. In addition, as shown in FIG. 2, the semiconductor fine particle crystal may have a plurality of shell layers.

(1c) Modified organic compound In one embodiment of the present invention, the semiconductor fine particle phosphor may have a modified organic compound on the surface of the shell layer. The modified organic compound affects the dispersibility of the semiconductor fine particle phosphor. Further, the modified organic compound has a function of confining electrons inside the semiconductor fine particle phosphor, a function of protecting the semiconductor fine particle phosphor from adverse effects from the outside, and a function of suppressing aggregation of the semiconductor fine particle phosphors.

  The modified organic compound has a feature of being coordinated or bonded to the surface of the shell layer of the semiconductor fine particle phosphor. Specifically, fatty acids represented by lauric acid, myristic acid, palmitic acid, stearic acid, etc., alkyl phosphines represented by tributylphosphine, trioctylphosphine, tridecylphosphine, etc., tributylphosphine oxide, trioctylphosphine Alkylphosphine oxides represented by oxides, tridecylphosphine oxides, etc., alkylamines represented by dodecylamine, hexadecylamine, oleylamine, etc., alkylthiols represented by dodecanethiol, hexadecanethiol, etc., and pyridine and It is preferable to use nitrogen-containing aromatic compounds such as quinoline.

(2) Energy band structure of semiconductor fine particle phosphor The semiconductor fine particle phosphor according to the present invention is characterized by an energy band structure.

FIG. 3 shows an energy band structure of a semiconductor fine particle phosphor having a core / shell structure in an embodiment of the present invention. In FIG. 3, the energy level at the lower end of the conduction band of the semiconductor crystal core is Ec (core), the energy level at the lower end of the conductor of the shell layer is Ec (shell), and the energy level at the upper end of the valence band of the semiconductor crystal core is Ev (core), Ev (shell) of the valence band of the shell layer, Ec ′, a quantum level formed by the confinement effect of electrons inside the semiconductor fine particle phosphor, and holes inside the semiconductor fine particle phosphor The quantum level formed by the confinement effect of is denoted by Ev ′. In this specification, the quantum level Ec ′ or Ev ′ means the one closest to Ec or Ev among a plurality of quantum levels existing at or above Ec or below Ev at room temperature (25 ° C.), respectively. To do. In addition, the electron and hole energy levels of the modified organic compound adhering to the surface of the semiconductor fine particle phosphor are denoted as E _HOMO and E _LUMO , respectively.

FIG. 3 shows that the energy levels Ec (core) and Ev (core) of the semiconductor crystal core are sandwiched between the energy levels Ec (shell) and Ev (shell) of the shell layer, and further the energy level Ec ( shell) and Ev (shell) are represented by energy band structures sandwiched between the energy levels E _HOMO and E _LUMO of the modified organic compound.

The energy barrier height Vc in the conduction band and the energy barrier height Vv in the valence band are expressed by the following equations (3) and (4), respectively.
Vc = Ec (shell) −Ec (core) (3)
Vv = Ev (shell) −Ev (core) (4)
The band gap Eg (core) of the semiconductor crystal core and the band gap Eg (shell) of the shell layer are represented by the following formulas (5) and (6), respectively.
Eg (core) = Ec (core) −Ev (core) (5)
Eg (shell) = Ec (shell) −Ev (shell) (6)
Patent Document 1 describes a semiconductor fine particle phosphor having a core / shell structure where Eg (core) <Eg (shell) as a semiconductor fine particle phosphor having high luminous efficiency. The semiconductor fine particle phosphor that satisfies the above conditions is considered to have the energy band structure shown in FIGS. Note that in this specification, the luminous efficiency is an index representing the rate at which photons are emitted when a phosphor absorbs one photon. In actual measurement, it is calculated by “number of emitted photons / number of absorbed photons”. Such luminous efficiency is sometimes referred to as internal quantum efficiency (IQE).

  The present inventor has found that the luminous efficiency is greatly improved when the semiconductor fine particle phosphor has the energy band structure shown in FIG. The energy band structure shown in FIG. 4A satisfies Vc> 0 and Vv <0 at the same time, and both absolute values of Vc and Vv are sufficiently large. Further, the quantum level Ec ′ of electrons and the quantum level Ev ′ of holes satisfy the above equations (1) and (2) at the same time. The reason why the luminous efficiency of the semiconductor fine particle phosphor having the energy band structure of FIG. 4A is high is that the probability of recombination of electrons and holes is high, and non-emissive transition via defect levels is suppressed. It is possible. Hereinafter, the recombination probability of electrons and holes and the suppression of non-emissive transition through defect levels will be described.

(2a) Recombination probability of electrons and holes The distribution state of electrons and holes in each energy band structure shown in FIG. 4 is shown in the column of the existence probability of electrons and the existence probability of holes in FIG.

  FIG. 4A shows a semiconductor fine particle phosphor that satisfies Vc> 0, Vv <0, and satisfies the above formulas (1) and (2). In the semiconductor fine particle phosphor, since the absolute values of the energy barrier height (Vc) of the conductor and the energy barrier height (Vv) of the valence band are large, electrons and holes are confined by the shell layer. Localizes in the core.

  On the other hand, the semiconductor fine particle phosphor of FIG. 4B satisfies Vc> 0 and Vv <0 and satisfies the above formulas (1) and (2), but the energy barrier height (Vc) of the conductor is high. Since the absolute value is not sufficiently large, electrons leak into the shell layer, and the existence probability of electrons spreads widely throughout the semiconductor crystal core and the shell layer.

  Similarly, the semiconductor fine particle phosphor of FIG. 4C satisfies Vc> 0 and Vv <0 and satisfies the above equations (1) and (2), but the energy barrier height (Vv) of the valence band. ) Is not sufficiently large, holes leak into the shell layer, and the probability of existence of holes spreads widely throughout the semiconductor crystal core and the shell layer.

  When Vc> 0 and Vv> 0 as shown in FIGS. 4D and 4E, or when Vc <0 and Vv <0 as shown in FIGS. The presence of electrons or holes is localized in the shell layer (FIGS. 4E and 4G), or spreads widely throughout the semiconductor crystal core and the shell layer (FIGS. 4D and 4F). ).

  Therefore, it can be seen that it is necessary to have the energy band structure of FIG. 4A in order to localize the existence probability of electrons and holes in the semiconductor crystal core.

  When electrons and holes are localized in the semiconductor crystal core, the probability of recombination between electrons and holes increases, and as a result, light emission is facilitated. On the other hand, when the existence probability of electrons or holes spreads in the semiconductor crystal core and the shell layer (FIGS. 4B, 4C, 4D, and 4F), the electrons or holes are localized in the shell layer. However, when electrons and holes are spatially separated (FIGS. 4E and 4G), recombination of electrons and holes is difficult to occur, and the light emission efficiency is lowered.

(2b) Suppression of non-emissive transition through defect levels On the surface of a semiconductor crystal, there are many defect levels due to dangling bonds. These defect levels capture electrons and holes and cause non-luminescent transitions. Therefore, recombination of electrons and holes through the defect level lowers the luminous efficiency of the semiconductor fine particle phosphor. In the semiconductor fine particle phosphor having a core / shell structure, the defect level on the surface of the semiconductor crystal core is inactivated by covering the surface of the semiconductor crystal core with a shell layer.

  4B to 4G, at least one of electrons and holes penetrates the shell layer and reaches the surface of the shell layer. In this case, electrons and holes that have reached the surface of the shell layer are captured by the defect level. As a result, the luminous efficiency of the semiconductor fine particle phosphor is lowered.

  On the other hand, in the semiconductor fine particle phosphor of FIG. 4A, since electrons and holes are confined in the semiconductor crystal core, non-luminescence transition through the defect level hardly occurs. Therefore, the luminous efficiency of the semiconductor fine particle phosphor is hardly lowered.

(3) Conditions for Improving Luminous Efficiency As a method for further improving the luminous efficiency of the semiconductor fine particle phosphor of the present invention, a shell layer having a large energy barrier is used and the thickness of the shell layer is increased. It is conceivable to reduce the lattice mismatch between the semiconductor crystal core and the shell layer. The energy barrier height and thickness of the shell layer, and the lattice mismatch between the semiconductor crystal core and the shell layer will be described below.

(3a) Energy barrier height and film thickness of shell layer In one embodiment of the present invention, the semiconductor fine particle phosphor has a large absolute value of the energy barrier Vc of the conductor and the energy barrier height Vv of the valence band. Electrons and holes are confined by the shell layer and are localized in the semiconductor crystal core. However, even in this case, a phenomenon may occur where electrons and holes leak into the shell layer and reach the shell layer surface due to the tunnel effect. Electrons and holes reaching the surface of the shell layer are deactivated due to defect levels and other factors. As a result, the luminous efficiency of the semiconductor fine particle phosphor is lowered. Therefore, it is preferable from the viewpoint of improving the light emission efficiency of the semiconductor fine particle phosphor to reduce the probability (tunnel probability) that electrons and holes leak into the shell layer due to the tunnel effect.

  As a method for reducing the tunnel probability, (1) a shell layer material capable of increasing the absolute values of the energy barrier height Vc of the conduction band and the energy barrier height Vv of the valence band is used. Increasing the layer thickness.

  In order to increase luminous efficiency, it is preferable to suppress the tunnel probability of electrons and holes to 1% or less.

  The lower limit of the thickness of the shell layer is preferably a thickness that can suppress the tunnel probability of electrons and holes to 1% or less from the viewpoint of light emission efficiency. Note that the upper limit of the film thickness is not particularly limited, but it is more preferable to set in consideration of the lattice mismatch with the semiconductor crystal core because the light emission efficiency can be further improved. In this case, the film thickness of the shell layer varies depending on the lattice mismatch ratio between the semiconductor crystal core material and the shell layer material, but is generally preferably 1.5 nm or less.

  The preferred thickness of the shell layer varies depending on the combination of the semiconductor crystal core material and the shell layer material. In the semiconductor fine particle phosphor having the core / shell structure, the preferable thickness of the shell layer is 0.4 to 1.5 nm for the InN / AlN semiconductor fine particle phosphor, and 1.1 to 1 for the InN / GaN semiconductor fine particle phosphor. 5 nm, 0.9 to 1.5 nm for InN / ZnO semiconductor fine particle phosphor, 0.9 to 1.5 nm for InN / MgO semiconductor fine particle phosphor, 1.5 nm for InN / MgS semiconductor fine particle phosphor, InP / ZnS semiconductor 0.9 to 1.5 nm for the fine particle phosphor, 1.3 to 1.5 nm for the InP / ZnSe semiconductor fine particle phosphor, 3.4 nm for the InP / AlP semiconductor fine particle phosphor, and 0.4 for the InP / AlN semiconductor fine particle phosphor. 5 to 1.5 nm, 0.8 to 1.5 nm for InP / MgO semiconductor fine particle phosphor, 1.4 for InP / MgS semiconductor fine particle phosphor 1.5 nm, InP / MgSe semiconductor fine particle phosphor is 2.2 nm, InP / 3C-SiC semiconductor fine particle phosphor is 2.1 nm, InP / 6H-SiC semiconductor fine particle phosphor is 1.4 to 1.5 nm, CdSe / ZnS semiconductor fine particle phosphor is 1.0 to 1.5 nm, CdSe / AlN semiconductor fine particle phosphor is 0.6 to 1.5 nm, CdSe / AlP semiconductor fine particle phosphor is 1.8 nm, and CdSe / GaN semiconductor fine particle phosphor is 6.4 nm, 2.6 nm for CeSe / ZnSe semiconductor fine particle phosphor, 0.9 to 1.5 nm for CdSe / MgO semiconductor fine particle phosphor, 2.8 nm for CdSe / MgS semiconductor fine particle phosphor, CdSe / MgSe semiconductor fine particle fluorescence 2.4 nm for the body, 1.4 to 1.5 for the CdSe / 6H—SiC semiconductor fine particle phosphor A m.

(3b) Lattice mismatch between the semiconductor crystal core and the shell layer In one embodiment of the present invention, the dangling bond on the surface of the semiconductor crystal core of the semiconductor fine particle phosphor is not formed by bonding with the dangling bond of the shell layer. It is activated. When the lattice constants of the semiconductor crystal core material and the shell layer material are the same, since both materials are lattice-matched, all the dangling bonds on the surface of the semiconductor crystal core are bonded to the dangling bonds of the shell layer. In practice, however, different materials rarely have the same lattice constant. Therefore, materials having different lattice constants are used for the semiconductor crystal core material and the shell layer material. In this case, dangling bonds that cannot be bonded are generated at the interface between the semiconductor crystal core and the shell layer. This dangling bond forms a defect level and contributes to a non-light emitting transition. Therefore, in order to increase the luminous efficiency, it is preferable to use a material having a small lattice mismatch ratio between the semiconductor crystal core material and the shell layer material. Specifically, it is preferable to use a material having a lattice mismatch rate of 15% or less.

(4) Other Methods for Improving Luminous Efficiency of Semiconductor Fine Particle Phosphor In one embodiment of the present invention, the semiconductor fine particle phosphor preferably uses a direct transition type semiconductor material as a semiconductor crystal core material. . When a direct transition type semiconductor material is used, a semiconductor fine particle phosphor with higher luminous efficiency can be realized than when an indirect transition type semiconductor material is used. Examples of the direct transition type semiconductor material include InN, InP, InAs, InSb, GaN, GaAs, GaSb, AlN, ZnO, ZnSe, ZnTe, CdS, CdSe, CdTe, and mixed crystals of these semiconductor materials.

  As the semiconductor crystal core material, it is preferable to use a semiconductor material that emits light in the visible wavelength region when fine particles are formed. This is because when it is used as a phosphor, it emits visible light and exhibits excellent characteristics in terms of illuminance. Examples of the semiconductor material that emits light in the visible wavelength region in the case of fine particles include InN, InP, InAs, InSb, GaP, GaAs, GaSb, AlP, AlAs, AlSb, ZnSe, ZnTe, CdS, CdSe, and CdTe. And mixed crystals of these semiconductor materials.

The material of the semiconductor fine particle phosphor is preferably a material having low harmfulness and environmental load.
The shell layer preferably also has a protective function for protecting the semiconductor crystal core from being adversely affected by the outside world. Specifically, the shell layer material may have a characteristic that hardly allows water and oxygen to pass therethrough. The semiconductor fine particle phosphor having the shell layer is excellent in that the luminous efficiency is high and the product life is long.

  When the semiconductor fine particle phosphor has a modified organic compound, the dispersibility of the semiconductor fine particles in a liquid or solid can be controlled. Furthermore, the modified organic compound can have a function of confining electrons in the semiconductor crystal core, a function of protecting the semiconductor fine particles from adverse effects from the outside, a function of suppressing aggregation of the semiconductor fine particles.

<Device using semiconductor fine particle phosphor>
The semiconductor fine particle phosphor according to the present invention exhibits excellent luminous efficiency. Therefore, when the half-particle fine phosphor is used, a device having excellent optical characteristics such as light emission efficiency can be realized. Specifically, the wavelength conversion member shown in FIG. 5, the light emitting device shown in FIG. 6, and the image display device shown in FIG. 7 are exemplified.

(1) Wavelength conversion member (1a) Structure of wavelength conversion member The wavelength conversion member in one embodiment of the present invention will be described with reference to FIG. FIG. 5 is a schematic cross-sectional view showing the wavelength conversion member 500 in one embodiment of the present invention. In the wavelength conversion member 500, the red light emitting semiconductor fine particle phosphor 501r, the green light emitting semiconductor fine particle phosphor 501g, and the blue light emitting semiconductor fine particle phosphor 501b are dispersed in the translucent material 502.

  The type of semiconductor fine particle phosphor 501 contained in the wavelength conversion member 500 is preferably one or more. When the wavelength converting member emits light with a single color having high color purity, it is preferable to use one kind of semiconductor fine particle phosphor having a narrow emission half width as the semiconductor fine particle phosphor 501. When the number of semiconductor fine particle phosphors 501 increases, there is a problem that the color rendering property of light emission is improved while the light emission efficiency is lowered. Therefore, the number of semiconductor fine particle phosphors 501 is preferably four or less from the viewpoint of luminous efficiency.

  As the translucent material 502, a material that does not absorb light emitted from the light source and the semiconductor fine particle phosphor is used. Furthermore, it is preferable to use a material that does not transmit moisture and oxygen. In this case, since the semiconductor fine particle phosphor can be prevented from being affected by moisture or oxygen by the light transmissive material, durability of the light emitting device and the image display device using the light transmissive material is improved. Examples of preferable translucent materials include translucent resins such as silicone resin, epoxy resin, acrylic resin, fluororesin, polycarbonate resin, polyimide resin, urea resin, aluminum oxide, silicon oxide (glass), yttria, and the like. The translucent inorganic material etc. can be illustrated.

(1b) Function of Wavelength Conversion Member The function of the wavelength conversion member in one embodiment of the present invention will be described with reference to FIG. The wavelength conversion member 500 absorbs at least a part of the incident light 503 and emits radiation light 504 having a wavelength different from that of the incident light.

  In FIG. 5, incident light 503 is incident on the wavelength conversion member 500. Part of the incident light 503 is absorbed by the shell layers of the semiconductor fine particle phosphors 501r, 501g, and 501b. The semiconductor fine particle phosphors 501r, 501g, and 501b that have absorbed light emit fluorescence having a wavelength different from that of the absorbed light from the semiconductor crystal core. On the other hand, the incident light 503 that has not been absorbed by the semiconductor fine particle phosphors 501r, 501g, and 501b passes through the wavelength conversion member as it is. Therefore, the radiated light 504 emitted from the wavelength converting member is light obtained by mixing the fluorescence emitted from the semiconductor fine particle phosphors 501r, 501g, and 501b with the transmitted light.

(2) Light-Emitting Device (2a) Structure of Light-Emitting Device A light-emitting device according to an embodiment of the present invention will be described with reference to FIG. FIG. 6 is a schematic cross-sectional view showing a light emitting device 600 according to an embodiment of the present invention.

  The light emitting device 600 has a structure in which a semiconductor light emitting diode element 601 and semiconductor fine particle phosphors 602 and 603 are combined. The light emitting element 601 is formed by laminating an n-side electrode 609, a semiconductor active layer 607, and a p-side electrode 608 in this order from the printed wiring board 614 side. The n-side electrode 609 is electrically connected to an n-electrode portion 610 provided from the top surface to the back surface of the printed wiring board 614 via a conductive adhesive 611. On the other hand, the p-side electrode 608 is electrically connected via a metal wire 613 and a p-electrode portion 612 provided from the upper surface to the back surface at a position different from the n-electrode portion of the printed wiring board 614. The inside of the frame 605 is filled with a translucent material 606 in which a plurality of semiconductor fine particle phosphors 602 and 603 are dispersed. The semiconductor light emitting element 601 is sealed with the light transmissive material 606.

(2b) Function of Light-Emitting Device At least part of light emitted from the semiconductor light-emitting diode element 601 is absorbed by the shell layers of the semiconductor fine particle phosphors 602 and 603. The semiconductor fine particle phosphors 602 and 603 that have absorbed light emit light having a wavelength different from that of the absorbed light from the semiconductor crystal core. As a result, the light emitting device 600 emits light in which light transmitted from the semiconductor light emitting diode element 601 that is not absorbed by the semiconductor fine particle phosphor and fluorescence emitted from the semiconductor fine particle phosphors 602 and 603 are mixed.

(2c) Light-Emitting Element In FIG. 6, a semiconductor light-emitting diode element is used as an example of the light-emitting element. However, a similar light-emitting device can be obtained by using another light-emitting element such as a semiconductor light-emitting laser diode element or an organic electroluminescence element. Can be produced.

(3) Image Display Device (3a) Structure of Image Display Device An image display device according to an embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a schematic exploded perspective view showing an image device 700 according to an embodiment of the present invention. FIG. 8 is a schematic exploded perspective view showing the liquid crystal unit 800 of the image device 700.

  In the image display device 700, a plurality (16 in FIG. 7) of light emitting devices 701 are disposed as light sources on the side surface of the transparent or translucent light guide plate 703, and a plurality of liquid crystals are adjacent to the upper surface of the light guide plate 703. An image display unit 705 including the unit 800 is provided. The emitted light 702 from the light emitting device 701 passes through the light guide plate 703 and is irradiated on the entire surface of the image display unit 705 as irradiation light 704. In the image display device 700, a light emitting device 701 that emits white light is used as a light source, a color filter 806 in the liquid crystal unit 800 is used to display each pixel, and each pixel is turned on and off in the liquid crystal unit 800. A thin film transistor 802 is used.

  The liquid crystal unit 800 includes a lower polarizing plate 801a, a transparent conductive film 803a having a thin film transistor 802, an alignment film 804a, a liquid crystal layer 805, an alignment film 804b, an upper thin film electrode 803b, a color filter 806, and an upper polarizing plate 801b in the above order. It becomes. The color filter 806 includes a plurality of types (three types in FIG. 8) of color filters 806r, 806g, and 806b, and each color filter transmits only light in a specific wavelength region. Each section of the color filter 806 is divided into sizes corresponding to the transparent conductive film 803a. In the liquid crystal portion 800, ON / OFF display can be performed by controlling transmission of light from the lower polarizing plate 801a to the upper polarizing plate 801b by the thin film transistor 802. The liquid crystal part having this structure is sometimes called a wavelength conversion part.

  The image display apparatus of the present invention is not limited to the structure shown above, and a conventionally known general structure can be adopted.

  The light guide plate 703 alleviates uneven brightness in the in-plane direction of the light 702 that is emitted from the light emitting device 701 that is a light source to the image display unit 705. If unevenness of brightness in the in-plane direction exists in the emitted light 702 from the light source, unevenness in the in-plane direction occurs in the brightness of the image display unit. By using the light guide plate 703, it is possible to irradiate the image display unit 705 with irradiation light 704 having a uniform in-plane intensity. An example of the light guide plate 703 is an acrylic resin plate whose surface is uneven. In the acrylic resin plate, light is scattered by the unevenness of the surface, so that light with uniform brightness in the in-plane direction can be emitted.

  The color filter 806 transmits only light having a specific wavelength in the irradiation light 704. Examples of the color filter material include dyes and pigments.

  The number of sections of the color filter is preferably 3 or more. This is because, if there are three sections, most of the naturally existing color tones can be reproduced on the image display unit. Moreover, it is preferable to use the color filter which permeate | transmits red, green, and blue, respectively for three divisions.

  FIG. 9 is a graph showing respective transmission spectra of a red color filter, a green color filter, and a blue color filter used in the image display device according to the embodiment of the present invention. The vertical axis represents transmittance (%), and the horizontal axis represents wavelength (nm). The color filter is not limited to the one having the transmission spectrum shown in the graph of FIG. 9, and a conventionally known general color filter can be used.

(3b) Function of Image Display Device The emitted light 702 emitted from the light emitting device 701 passes through the light guide plate 703 and enters the plurality of liquid crystal units 800. In the liquid crystal unit 800, arbitrary light is emitted as a result of controlling the transmittance of the irradiation light 704 by the thin film transistor 802. Therefore, the image display unit 705 can display images, characters, and the like as a result of each liquid crystal unit 800 transmitting arbitrary light.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example and a comparative example, this invention is not limited to these.

<Examination of luminous efficiency of semiconductor fine particle phosphor>
The relationship between the core / shell structure of the semiconductor fine particle phosphor and the light emission efficiency was examined.

(Examination 1: Examination of energy barrier heights Vv and Vc)
The relationship between the combination of the semiconductor crystal core material and the shell layer material, the valence band, and the energy barrier heights Vv and Vc of the conductor was examined.

  As the semiconductor crystal core material, InN and InP, which are III-V group compound semiconductor materials, and CdSe, which is a II-VI group compound semiconductor material, were used from the viewpoint that visible light can be emitted. As the shell layer material, a group III-V compound semiconductor material AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, a group II-VI compound semiconductor material ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, MgO, MgS, MgSe, IV-IV group compound semiconductor material 3C-SiC, 6H-SiC was used.

  Table 1 shows the calculation results of the energy barrier heights Vv and Vc in the combination of each semiconductor crystal core material and each shell layer material. In the evaluation column, A satisfying the condition of Vv <0 and Vc> 0 and A not satisfying the condition of Vv <0 and Vc> 0.

  From the viewpoint of luminous efficiency, the semiconductor fine particle phosphor preferably has an energy band structure shown in FIGS. 4A, 4B, and 4C. That is, it is preferable to satisfy the conditions of Vv <0 and Vc> 0.

  From Table 1, from the viewpoint of energy barrier height, preferable combinations of semiconductor crystal core material / shell layer material are InN / AlN, InN / GaN, InN / ZnO, InN / MgO, InN / MgS, InN / MgSe, InP. / AlN, InP / AlP, InP / AlAs, InP / GaN, InP / GaP, InP / ZnS, InP / ZnSe, InP / CdS, InP / MgO, InP / MgS, InP / MgSe, InP / 3C-SiC, InP / 6H-SiC, CdSe / AlN, CdSe / AlP, CdSe / GaN, CdSe / ZnS, CdSe / ZnSe, CdSe / CdS, CdSe / MgO, CdSe / MgS, CdSe / MgSe, CdSe / 6H-SiC I understand.

  In addition, it is considered that a preferable energy band structure can be obtained even when InGaN, InGaP, ZnCdSe, or the like having properties similar to InN, InP, and CdSe is used for the semiconductor crystal core.

(Examination 2: Examination of quantum levels)
Next, the quantum level was calculated using the preferable semiconductor crystal core material / shell layer material combination obtained from the result of Study 1. In this study, the quantum level was determined when the semiconductor crystal core emitted red light of 620 nm. The quantum level was calculated using an effective mass approximation method (EMA method). The results are shown in Table 2. In the evaluation column, Ev′−Ev (shell)> 0 (ie, equation (2) Ev ′> Ev (shell)) and Ec′−Ec (shell) <0 (ie, equation (1) Ec ′ <Ec). (Shell)) satisfying the condition of (shell)) and A not satisfying is expressed as B.

  From Table 2, when the combination of the semiconductor crystal core material / shell layer material is InP / GaN, InP / CdS, CdSe / GaN, CdSe / CdS, the formula (1) is not satisfied. Therefore, as shown in FIG. 4B, it was found that electrons are not confined in the semiconductor crystal core, and the existence probability of electrons spreads throughout the semiconductor crystal core and the shell layer.

  On the other hand, when the combination of the semiconductor crystal core material / shell layer material is InN / MgSe, InP / GaP, or InP / AlAs, the formula (2) is not satisfied. Therefore, as shown in FIG. 4C, it was found that holes are not confined to the semiconductor crystal core, and the probability of existence of holes spreads throughout the semiconductor crystal core and the shell layer.

  Therefore, as shown in FIG. 4A, as a combination of semiconductor crystal core material / shell layer material of semiconductor fine particle phosphor having an energy band structure in which electrons and holes are confined in the semiconductor crystal core, InN / AlN, InN / GaN, InN / ZnO, InN / MgO, InN / MgS, InP / AlN, InP / AlP, InP / ZnS, InP / ZnSe, InP / MgO, InP / MgS, InP / MgSe, InP / 3C-SiC, Examples include InP / 6H-SiC, CdSe / AlN, CdSe / AlP, CdSe / GaN, CdSe / ZnS, CdSe / ZnSe, CdSe / MgO, CdSe / MgS, CdSe / MgSe, and CdSe / 6H-SiC.

  Even when InGaN, InGaP, ZnCdSe or the like having properties similar to InN, InP, or CdSe is used for the semiconductor crystal core, it is considered that a preferable energy band structure can be obtained by appropriately selecting the shell layer material.

(Examination 3: Examination of shell layer thickness)
Based on the result of Study 2, the thickness of the shell layer was studied. It is considered that the thickness of the shell layer is important in order to suppress the leakage of electrons and holes to the shell layer due to the tunnel effect and improve the light emission efficiency.

  From the viewpoint of suppressing leakage of electrons and holes, the film thickness of the shell layer was calculated when the tunnel probability of electrons or holes from the semiconductor crystal core to the shell layer was 1%. The results are shown in Table 3. In the evaluation column, the case where the required film thickness of the shell layer was 1.5 nm or less was indicated as A, and the case where it exceeded 1.5 nm was indicated as B.

  When the combination of semiconductor crystal core material / shell layer material is InP / AlP, InP / MeSe, InP / 3C-SiC, CdSe / AlP, CdSe / GaN, CdSe / ZnSe, CdSe / MgS, CdSe / MgSe, In order to suppress the hole tunneling probability to 1% or less, the thickness of the shell layer needs to be larger than 1.5 nm. When the thickness of the shell layer exceeds 1.5 nm, it is difficult to realize from the viewpoint of lattice mismatch with the semiconductor crystal core. Therefore, from the viewpoint of tunnel probability, the combinations of semiconductor crystal core material / shell layer material are InN / AlN, InN / GaN, InN / ZnO, InN / MgO, InN / MgS, InP / AlN, InP / ZnS, InP. / ZnSe, InP / MgO, InP / MgS, InP / 6H—SiC, CdSe / AlN, CdSe / ZnS, CdSe / MgO, and CdSe / 6H—SiC are preferable.

  Even when InGaN, InGaP, ZnCdSe, or the like having properties similar to InN, InP, or CdSe is used for the semiconductor crystal core, it is considered that a preferable shell film thickness can be obtained by appropriately selecting the shell layer material.

(Examination 4: Calculation of lattice mismatch rate)
Based on the results of Study 2, the lattice mismatch rate between the semiconductor crystal core material and the shell layer material was examined. In order to suppress defects at the interface between the semiconductor crystal core and the shell layer, it is preferable that the lattice mismatch ratio between the two is small.

  Table 4 shows the calculation results of the lattice mismatch ratio between materials in each semiconductor crystal core material / shell layer material combination. In the evaluation column, the case where the lattice mismatch rate is 15% or less is indicated as A, and the case where it exceeds 15% is indicated as B.

  From the viewpoint of luminous efficiency, the lattice mismatch rate is preferably 15% or less. Therefore, the combinations of semiconductor crystal core material / shell layer material are InN / GaN, InN / ZnO, InP / AlP, InP / ZnS, InP / ZnSe, InP / MgO, InP / MgS, InP / MgSe, CdSe / AlP, CdSe / GaN, CdSe / ZnS, CdSe / ZnSe, CdSe / MgO, CdSe / MgS, and CdSe / MgSe are preferable.

  Even when InGaN, InGaP, ZnCdSe, or the like having properties similar to InN, InP, or CdSe is used for the semiconductor crystal core, it is considered that a preferable lattice mismatch rate can be obtained by appropriately selecting the shell layer material. .

(Examination 5: Calculation of shell layer thickness and lattice mismatch rate)
It is preferable that the semiconductor fine particle phosphor has a sufficiently small loss of light emission efficiency due to the tunnel effect and has a sufficiently small interface defect (lattice mismatch rate) between the semiconductor crystal core and the shell layer. Therefore, from the results of Study 3 and Study 4, the combinations of semiconductor crystal core material / shell layer material are InN / GaN, InN / ZnO, InP / ZnS, InP / ZnSe, InP / MgO, InP / MgS, and CdSe / ZnS. CdSe / MgO is preferred.

  Even when InGaN, InGaP, ZnCdSe, or the like having properties similar to InN, InP, or CdSe is used for the semiconductor crystal core, a preferable film thickness and lattice mismatch ratio can be obtained by appropriately selecting the shell layer material. It is thought that.

<Synthesis of semiconductor fine particle phosphor>
Based on the results of examinations 1 to 4, a semiconductor fine particle phosphor having a core / shell structure was synthesized and evaluated.

  In the following examples, the crystal structure measurement of the semiconductor fine particle phosphor is performed using a powder X-ray diffraction measurement device Ultimate IV manufactured by Rigaku Co., Ltd. A company transmission electron microscope JEM-2100 was used.

(Example 1: Synthesis of InN / GaN semiconductor fine particle phosphor)
In Example 1, an InN / GaN semiconductor fine particle phosphor was synthesized using InN as the semiconductor crystal core material and GaN as the shell layer material. Hereinafter, the semiconductor fine particle phosphor having the combination of the semiconductor crystal core material (A) and the shell layer material (B) of the semiconductor fine particle phosphor is referred to as “A / B semiconductor fine particle phosphor”.

(Synthesis of InN semiconductor crystal core)
200 mL of 1-octadecene was weighed in a glove box in a dry nitrogen atmosphere. In 1-octadecene, 2.2 g (10.0 mmol) of indium trichloride which is a group III metal element raw material of a semiconductor crystal core and 0.23 g (10.0 mmol) of lithium amide which is a group V element raw material, and a modified organic compound After adding 4.8 g (20.0 mmol) of hexadecylamine, the raw material solution A was obtained by stirring at 20 ° C. for 10 minutes.

  Next, the raw material solution A was heated for 5 hours while stirring in a pressure vessel in a nitrogen atmosphere to synthesize the materials contained in the raw material solution A to obtain a synthetic solution B. Then, the synthetic solution B after completion of the synthesis reaction was cooled by naturally releasing heat to room temperature, and the synthetic solution B was recovered in a dry nitrogen atmosphere.

  An operation for precipitating the semiconductor fine particle phosphor by adding 200 mL of dehydrated methanol as a poor solvent to the synthetic solution B, an operation for precipitating the semiconductor fine particle phosphor by centrifuging at 4000 rpm for 10 minutes, The dehydrated toluene solution C containing the semiconductor fine particle phosphor having a specific particle diameter was obtained by performing a classification step in which the operation of re-dissolving the semiconductor fine particle phosphor was added 10 times each. And solid powder D was collect | recovered by taking out a part of dehydrated toluene solution C and evaporating a dehydrated toluene solvent.

  When the diffraction peak of the solid powder D was observed by powder X-ray diffraction, a diffraction peak was observed at the position of InN. Thus, it was confirmed that the solid powder D was InN semiconductor fine particles. Further, the solid powder D was directly observed with a transmission electron microscope, 20 particle diameters were measured, and the average particle diameter was calculated from the average value of the respective particle diameter values. Was 1.6 nm. The InN semiconductor fine particles correspond to a semiconductor crystal core.

(Synthesis of GaN shell layer)
In a glove box in a dry nitrogen atmosphere, in 200 mL of 1-octadecene, solid powder D composed of an InN semiconductor crystal core, 3.5 g (20.0 mmol) of gallium trichloride which is a group III metal element raw material of the shell layer, and V After adding and mixing 0.46 g (20.0 mmol) of lithium amide, which is a group element material, and 9.7 g (40.0 mmol) of hexadecylamine, which is a modified organic compound, the mixture is stirred at 20 ° C. for 10 minutes. A raw material solution E was obtained.

  Next, the raw material solution E was heated in a pressure vessel in a nitrogen atmosphere for 3 hours while being stirred, thereby synthesizing materials contained in the raw material solution E to obtain a synthetic solution F. Then, the synthetic solution F after completion of the synthesis reaction was cooled by naturally releasing heat to room temperature, and the synthetic solution F was recovered in a dry nitrogen atmosphere. InN / GaN semiconductor fine particle phosphor was precipitated by adding dehydrated methanol as a poor solvent to the synthetic solvent F and centrifuging, and solid powder G was recovered. A dehydrated toluene solution H was prepared by adding dehydrated toluene to the solid powder G.

  The obtained InN / GaN semiconductor fine particle phosphor was confirmed to have a light emission efficiency of 28.6% by performing photoluminescence measurement. Further, the solid powder G was directly observed with a transmission electron microscope, 20 particle diameters were measured, and the average particle diameter was calculated from the average value of the respective particle diameter values. The average particle size of was 4.2 nm. Considering that the average particle diameter of the semiconductor crystal core made of InN semiconductor fine particles is 1.6 nm, the average film thickness of the shell layer is considered to be 1.3 nm.

  Table 5 summarizes the characteristics of the InN / GaN semiconductor fine particle phosphor.

(Example 2: Synthesis of InN / ZnO semiconductor fine particle phosphor)
In Example 2, the InN / ZnO semiconductor fine particle phosphor was synthesized. In Example 2, synthesis was performed using the same method as in Example 1 except that the raw materials for the ZnO shell layer were different.

  That is, an InN semiconductor crystal core was synthesized using the same method as in Example 1. Thereafter, in a glove box, in 200 mL of ethanol, InN semiconductor crystal core, 4.4 g (20.0 mmol) of zinc acetate dihydrate which is a group II metal element raw material of the shell layer, and water which is a group VI element raw material Lithium oxide monohydrate (1.7 g, 40.0 mmol) was mixed.

Table 5 shows the characteristics of the obtained InN / ZnO semiconductor fine particle phosphor.
(Example 3: Synthesis of InN / AlN semiconductor fine particle phosphor)
In Example 3, the InN / AlN semiconductor fine particle phosphor was synthesized. In Example 3, the synthesis was performed using the same method as in Example 1 except that the raw material of the AlN shell layer was different.

  That is, an InN semiconductor crystal core was synthesized using the same method as in Example 1. Thereafter, in a glove box, in 200 mL of 1-octadecene, 2.7 g (20.0 mmol) of aluminum trichloride which is a group III metal element raw material of the InN semiconductor crystal core and shell layer, and lithium amide which is a group V element raw material 0.46 g (20.0 mmol) and 9.7 g (40.0 mmol) of hexadecylamine which is a modified organic compound were added and mixed.

Table 5 shows the characteristics of the obtained InN / AlN semiconductor fine particle phosphor.
(Example 4: Synthesis of InN / MgO semiconductor fine particle phosphor)
In Example 4, the InN / MgO semiconductor fine particle phosphor was synthesized. In Example 4, the synthesis was performed using the same method as in Example 1 except that the raw material of the MgO shell layer was different.

That is, an InN semiconductor crystal core was synthesized using the same method as in Example 1. Then, in a glove box, in 200 mL of ethanol, InN semiconductor crystal core, 4.3 g (20.0 mmol) of magnesium acetate tetrahydrate which is a group II metal element raw material of the shell layer, and a group VI element raw material Lithium hydroxide monohydrate (1.7 g, 40.0 mmol) was mixed.
Table 5 shows the characteristics of the obtained InN / MgO semiconductor fine particle phosphor.

(Example 5: Synthesis of InN / MgS semiconductor fine particle phosphor)
In Example 5, the InN / MgS semiconductor fine particle phosphor was synthesized. In Example 5, synthesis was performed using the same method as in Example 1 except that the raw material of the MgO shell part was different.

That is, an InN semiconductor crystal core was synthesized using the same method as in Example 1. Thereafter, in a glove box, in 200 mL of 1-octadecene, with an InN semiconductor crystal core, 4.3 g (20.0 mmol) of magnesium acetate tetrahydrate which is a Group II metal element raw material of the shell layer, and a Group VI element raw material 0.6 g (20.0 mmol) of certain sulfur, 22.2 g (60.0 mmol) of trioctylphosphine which is a modified organic compound, and 9.7 g (40.0 mmol) of hexadecylamine were added and mixed.
Table 5 shows the characteristics of the obtained InN / MgS semiconductor fine particle phosphor.

(Comparative Example 1: Synthesis of InN semiconductor fine particle phosphor)
In Comparative Example 1, an InN semiconductor fine particle phosphor was synthesized. In Comparative Example 1, the synthesis was performed using the same method as in Example 1 except that the shell layer was not synthesized. That is, an InN semiconductor crystal core was synthesized using the same method as in Example 1.

Table 5 shows the characteristics of the obtained InN semiconductor fine particle phosphor.
(Comparative Example 2: Synthesis of InN / ZnS semiconductor fine particle phosphor)
In Comparative Example 2, an InN / ZnS semiconductor fine particle phosphor was synthesized. In Comparative Example 2, synthesis was performed using the same method as in Example 1 except that the raw material for the MgO shell layer was different.

  That is, an InN semiconductor crystal core was synthesized using the same method as in Example 1. Thereafter, in 200 g of 1-octadecene, 12.6 g (20.0 mmol) of zinc stearate as a group II metal element raw material of the shell layer and sulfur as a group VI element raw material in 200 mL of 1-octadecene. .6 g (20.0 mmol), 22.2 g (60.0 mmol) of trioctylphosphine, which is a modified organic compound, and 9.7 g (40.0 mmol) of hexadecylamine were added and mixed.

Table 5 shows the characteristics of the obtained InN / ZnS semiconductor fine particle phosphor.
<Consideration of relationship between core / shell structure of semiconductor fine particle phosphor and luminous efficiency>
Hereinafter, the influence of the energy band structure of the semiconductor fine particle phosphor having the core / shell structure on the light emission efficiency will be examined.

  Table 5 shows the light emission efficiency of the semiconductor fine particle phosphor obtained by synthesizing different types of shell layers on the InN semiconductor crystal core. Here, it can be confirmed that the InN / ZnS semiconductor fine particle phosphor of Comparative Example 2 has lower luminous efficiency than the InN semiconductor fine particle phosphor of Comparative Example 1 having no shell layer. This is considered to be because when the ZnS shell layer is synthesized, electrons are confined in the semiconductor crystal core, while holes are confined in the shell layer, so that the recombination probability between electrons and holes is greatly reduced. From this, in order to synthesize a semiconductor fine particle phosphor having a core / shell structure with high luminous efficiency, the condition that the energy gap of a conventionally known semiconductor crystal core is smaller than the energy gap of the shell layer (Eg (core) < Eg (shell)) alone is not sufficient, and it is understood that it is necessary to satisfy the expressions (1) and (2).

  Further, the InN / AlN semiconductor fine particle phosphor of Example 3, the InN / MgO semiconductor fine particle phosphor of Example 4, the InN / MgS semiconductor fine particle phosphor of Example 5 are the InN core particle phosphor of Comparative Example 1, and the comparison It can be confirmed that the luminous efficiency is higher than that of the InN / ZnS semiconductor fine particle phosphor of Example 2. This is thought to be due to the confinement effect of electrons and holes by the shell layer. From this, in order to synthesize a semiconductor fine particle phosphor having a core / shell structure with high luminous efficiency, the equations (1) and (2) are satisfied, and the loss of electrons and holes due to the tunnel effect is suppressed. Thus, it can be seen that it is necessary to sufficiently increase the thickness of the shell layer.

  The InN / GaN semiconductor fine particle phosphor of Example 1 and the InN / ZnO semiconductor fine particle phosphor of Example 2 are the InN / AlN semiconductor fine particle phosphor of Example 3, and the InN / MgO semiconductor fine particle phosphor of Example 4. It can be confirmed that the luminous efficiency is higher than that of the InN / MgS semiconductor fine particle phosphor of Example 5. This is presumably because the lattice mismatch rate between the semiconductor crystal core material and the shell layer material was small, and the deactivation of electrons and holes due to defects at the interface between the semiconductor crystal core and the shell layer could be sufficiently suppressed. Therefore, in order to synthesize a semiconductor fine particle phosphor having a core / shell structure with high luminous efficiency, it is necessary to use a shell layer material having a small lattice mismatch with the semiconductor crystal core material in addition to confining electrons and holes. I understand that there is.

(Example 6: Synthesis of InN / GaN semiconductor fine particle phosphors having different shell layer thicknesses)
In Example 6, the synthesis was performed using the same method as in Example 1 except that the amount of the raw material for the GaN shell layer was different. A plurality of InN / GaN semiconductor fine particle phosphors having different shell layer thicknesses were synthesized by changing the amount of the raw material of the GaN shell layer. Using the obtained semiconductor fine particle phosphor, the relationship between the shell layer thickness and the luminous efficiency was examined. The results are shown in FIG.

<Consideration of the relationship between shell layer thickness and luminous efficiency of semiconductor fine particle phosphor>
Below, the influence which the change of the shell layer film thickness of a semiconductor fine particle fluorescent substance has on luminous efficiency is examined.

  FIG. 10 is a graph showing the relationship between the GaN shell film thickness and the light emission efficiency of the InN / GaN semiconductor fine particle phosphor. From FIG. 10, the luminous efficiency becomes maximum when the shell layer thickness is 1.1 nm to 1.5 nm, and it can be confirmed that the luminous efficiency tends to decrease even when the thickness is thinner or thicker. In addition, the shell layer thickness at which the luminous efficiency has the maximum value is close to the value of the shell layer thickness that can be sufficiently reduced in the loss of electrons and holes due to the tunnel effect, as calculated in Study 3 and Table 3. Was confirmed.

  In FIG. 10, when the shell layer thickness is less than 1.1 nm, the luminous efficiency increases as the shell layer thickness increases. This is considered to be because the confinement effect of electrons and holes becomes stronger and the loss of electrons and holes is reduced as the shell layer becomes thicker. This value is in good agreement with the theoretical calculation result of the shell layer thickness obtained in Table 3. On the other hand, when the shell layer thickness exceeds 1.5 nm, the luminous efficiency tends to decrease as the shell layer becomes thicker. This is presumably because lattice defects occurred due to lattice mismatch between the semiconductor crystal core and the shell layer as the shell layer became thicker.

  InN / AlN, InN / ZnO, InN / MgO, InN / MgS, InP / ZnS, InP / ZnSe, InP / AlP, InP / AlN, InP / MgO, InP / MgS, InP / MgSe, InP / 3C-SiC, Core / shell structure of InP / 6H-SiC, CdSe / ZnS, CdSe / AlN, CdSe / AlP, CdSe / GaN, CdSe / ZnSe, CdSe / MgO, CdSe / MgS, CdSe / MgSe, CdSe / 6H-SiC Also in the semiconductor fine particle phosphor, the tendency of the light emission efficiency to decrease below the required shell layer thickness shown in Table 3 was confirmed, similar to the tendency of the InN / GaN semiconductor fine particle phosphor shown in FIG.

(Examples 7 to 15 and Comparative Examples 3 to 4: Synthesis of Semiconductor Fine Particle Phosphor Having InP Semiconductor Crystal Core)
In the same manner as in Example 1, using the synthetic raw materials shown in Table 6, InP / AlN, InP / AlP, InP / ZnS, InP / ZnSe, InP / MgO, InP / MgS, InP in Examples 7 to 15 / MgSe, InP / 3C-SiC, InP / 6H-SiC core / shell structure semiconductor fine particle phosphor, Comparative Example 3 InP semiconductor fine particle phosphor and Comparative Example 4 InP / ZnO semiconductor fine particle phosphor went.

  The energy band structure, lattice mismatch rate, luminous efficiency, and shell layer average film thickness of the obtained semiconductor fine particle phosphor were measured in the same manner as in Example 1. The results are shown in Table 6.

  From the results shown in Table 6, in the semiconductor fine particle phosphor having the InP semiconductor crystal core, similarly to the semiconductor fine particle phosphor having the InN semiconductor crystal core, when the energy band structure shown in FIG. Was confirmed to be excellent.

(Examples 16 to 24, Comparative Examples 5 to 6: Synthesis of a semiconductor fine particle phosphor having a CdSe semiconductor crystal core)
Using the synthetic raw materials shown in Table 6, in the same manner as in Example 1, CdSe / AlN, CdSe / AlP, CdSe / ZnS, CdSe / ZnSe, CdSe / MgO, CdSe / MgS, CdSe of Examples 16-24 / MgSe, CdSe / 6H—SiC core / shell structure semiconductor fine particle phosphor, Comparative Example 5 CdSe semiconductor fine particle phosphor and Comparative Example 6 CdSe / GaP semiconductor fine particle phosphor were synthesized.

  The energy band structure, lattice mismatch rate, luminous efficiency, and shell layer average film thickness of the obtained semiconductor fine particle phosphor were measured in the same manner as in Example 1. The results are shown in Table 6.

  From the results of Table 6, in the semiconductor fine particle phosphor having the CdSe semiconductor crystal core, similarly to the semiconductor fine particle phosphor having the InN semiconductor crystal core, when the energy band structure shown in FIG. Was confirmed to be excellent.

<Manufacture of wavelength conversion member>
Using the semiconductor fine particle phosphors synthesized in Examples 1 to 5, 7 to 24, and Comparative Examples 1 to 6, a wavelength conversion member was manufactured and evaluated. In the following Examples, silicone resin SCR-1015 manufactured by Shin-Etsu Chemical Co., Ltd. was used as the silicone resin. In the following examples, three types of semiconductor fine particle phosphors each emitting red, green, and blue are mixed and used, and when the wavelength conversion member is excited with 405 nm blue-violet light, the white color temperature is 7000K. Manufacture was performed by appropriately adjusting the mixing amount of the red phosphor, the green phosphor, and the blue phosphor so as to emit light. In addition, the light emission measurement system MCPD-7000 by Otsuka Electronics Co., Ltd. was used for the measurement of the luminous efficiency of the wavelength conversion member.

(Example A1: Wavelength converting member using InN / GaN semiconductor fine particle phosphor)
In Example A1, the wavelength conversion member as shown in FIG. 5 was produced by sealing the InN / GaN semiconductor fine particle phosphor synthesized in Example 1 with a silicone resin.

  Using the method of Example 1, three types of InN / GaN semiconductor fine particle phosphors each emitting red, green, and blue light were synthesized. These three types of InN / GaN semiconductor fine particle phosphors were mixed with about 500 mg of silicone resin A solution. Then, it mixed with about 500 mg of silicone resin B liquid. The obtained silicone resin mixed solution was applied onto a slide glass and cured by heating at 80 ° C. for 1 hour and at 150 ° C. for 5 hours. Then, the wavelength conversion member of Example A1 was produced by removing the slide glass.

  When optical evaluation of the obtained wavelength conversion member was performed, it was confirmed that the luminous efficiency was 16.3%.

(Examples A2 to A5, Comparative Examples A1 to A2: Wavelength conversion members using various semiconductor fine particle phosphors)
In Examples A2 to A5 and Comparative Examples A1 to A2, the semiconductor fine particle phosphor having the core / shell structure of InN / ZnO, InN / AlN, InN / MgO, InN / MgS of Examples 2 to 5, A wavelength conversion member was produced in which the InN semiconductor fine particle phosphor and the InN / ZnS semiconductor fine particle phosphor of Comparative Example 2 were sealed with a silicone resin. The wavelength conversion members of Examples A2 to A5 and Comparative Examples A1 to A2 were prepared using the same method as Example A1 except for the type of semiconductor fine particle phosphor. Table 7 shows the characteristics of the obtained wavelength conversion member.

(Examples A6 to A14, Comparative Examples A3 to A4: Wavelength conversion member using semiconductor fine particle phosphor having InP semiconductor crystal core)
In Examples A6 to A14, InP / AlN, InP / AlP, InP / ZnS, InP / ZnSe, InP / MgO, InP / MgS, InP / MgSe, InP / 3C-SiC, synthesized in Examples 7 to 15, InP / 6H—SiC core / shell structure semiconductor fine particle phosphor, Comparative Example 3A, InP semiconductor fine particle phosphor of Comparative Example 3 and Comparative Example 4A, InP / ZnO semiconductor fine particle phosphor of Comparative Example 4 A wavelength conversion member sealed with a silicone resin was produced. These wavelength conversion members were produced using the same method as in Example A1 except for the type of semiconductor fine particle phosphor. Table 7 shows the characteristics of the obtained wavelength conversion member.

(Examples A15 to A23, Comparative Examples A5 to A6: Wavelength conversion member using semiconductor fine particle phosphor having InP semiconductor crystal core)
In Examples A15 to A22, CdSe / AlN, CdSe / AlP, CdSe / GaN, CdSe / ZnS, CdSe / ZnSe, CdSe / MgO, CdSe / MgS, CdSe / MgSe, CdSe / A semiconductor fine particle phosphor having a 6H-SiC core / shell structure, in Comparative Example A5, the CdSe semiconductor fine particle phosphor of Comparative Example 5 and in Comparative Example A6, the CdSe / GaP semiconductor fine particle phosphor of Comparative Example 6 were replaced with a silicone resin. A wavelength conversion member sealed in the above was produced. These wavelength conversion members were produced using the same method as in Example A1 except for the type of semiconductor fine particle phosphor. Table 7 shows the characteristics of the obtained wavelength conversion member.

<Consideration of Relationship between Core / Shell Structure of Semiconductor Fine Particle Phosphor and Luminous Efficiency of Wavelength Conversion Member>
Hereinafter, the influence of the energy band structure of the semiconductor fine particle phosphor having the core / shell structure on the light emission efficiency of the wavelength conversion member will be examined.

  Table 7 shows the luminous efficiency of the wavelength conversion member manufactured using various semiconductor fine particle phosphors. The light emission efficiency of the wavelength conversion member shows the same tendency as the light emission efficiency of the semiconductor fine particle phosphor shown in Table 5. Therefore, it can be confirmed that the light emission efficiency is improved also in the wavelength conversion member manufactured using the semiconductor fine particle phosphor of the present invention.

  In addition, not only the semiconductor fine particle phosphor having the InN semiconductor crystal core but also the wavelength conversion member using the InP semiconductor crystal core and the semiconductor fine particle phosphor having the CdSe semiconductor crystal core, it was confirmed that the luminous efficiency was improved.

<Manufacture of light emitting device>
Light emitting devices were manufactured and evaluated by combining the semiconductor fine particle phosphors synthesized in Examples 1 to 5, 7 to 24, and Comparative Examples 1 to 6 and semiconductor light emitting diode elements. In manufacturing the light emitting device, the silicone resin SCR-1015 manufactured by Shin-Etsu Chemical Co., Ltd. was used as the silicone resin. Furthermore, using a semiconductor light emitting diode element emitting blue light of 450 nm and a semiconductor fine particle phosphor emitting red and green respectively, the amount of the phosphor is adjusted appropriately so that white light emission with a color temperature of 5000K can be obtained. The light emitting device was manufactured.

  Note that a light emission measurement system MCPD-7000 manufactured by Otsuka Electronics Co., Ltd. was used for measuring the light emission efficiency of the light emitting device.

(Example B1: Light emitting device using InN / GaN semiconductor fine particle phosphor)
In Example B1, the InN / GaN semiconductor fine particle phosphor synthesized in Example 1 was sealed in a silicone resin to produce a light emitting device as shown in FIG.

  First, an InN / GaN semiconductor fine particle phosphor that emits red or green light was synthesized using the method of Example 1. These two types of InN / GaN semiconductor fine particle phosphors were mixed with about 500 mg of silicone resin A solution. Then, it mixed with about 500 mg of silicone resin B liquid. The obtained silicone resin mixed solution was filled on the light emitting element, and was heat-cured at 80 ° C. for 1 hour and at 150 ° C. for 5 hours to produce a light emitting device of Example B1.

(Examples B2 to B5, Comparative Examples B1 to B2: Light-emitting devices using various semiconductor fine particle phosphors)
In Examples B2 to B5 and Comparative Examples B1 and B2, semiconductor fine particles having a core-shell structure of InN / ZnO, InN / AlN, InN / MgO, and InN / MgS synthesized in Examples 2-5 and Comparative Examples 1-2 A light-emitting device using a phosphor, an InN semiconductor fine particle phosphor, and an InN / ZnS semiconductor fine particle phosphor was manufactured. The light emitting devices of Examples B2 to B5 and Comparative Examples B1 to B2 were prepared using the same method as Example B1 except for the type of semiconductor fine particle phosphor.

  The luminous efficiency of the obtained light emitting device was confirmed based on the luminous efficiency of the light emitting device of Example B1. The results are shown in Table 8.

(Examples B6 to B14, Comparative Examples B3 to B4: Light-emitting devices using semiconductor fine particle phosphors having InP semiconductor crystal cores)
In Examples B6 to B14 and Comparative Examples B3 to B4, InP / AlN, InP / AlP, InP / ZnS, InP / ZnSe, InP / MgO, InP / synthesized in Examples 7 to 15 and Comparative Examples 3 to 4 were used. A light emitting device using a semiconductor fine particle phosphor having a core / shell structure of MgS, InP / MgSe, InP / 3C-SiC, InP / 6H-SiC, an InP semiconductor fine particle phosphor, and an InP / ZnO semiconductor fine particle phosphor is manufactured. did. These light emitting devices were produced using the same method as in Example B1 except for the type of semiconductor fine particle phosphor.

  The luminous efficiency of the obtained light emitting device was confirmed based on the luminous efficiency of the light emitting device of Example B1. The results are shown in Table 8.

(Examples B15 to B23, Comparative Examples B5 to B6: Light-emitting devices using semiconductor fine particle phosphors having InP semiconductor fine particle phosphor cores)
In Examples B15 to B23 and Comparative Examples B5 to B6, CdSe / AlN, CdSe / AlP, CdSe / GaN, CdSe / ZnS, CdSe / ZnSe, CdSe / C synthesized in Examples 16 to 13 and Comparative Examples 5 to 6 were used. A light emitting device using a semiconductor fine particle phosphor having MgO, CdSe / MgS, CdSe / MgSe, CdSe / 6H-SiC core / shell structure, CdSe semiconductor fine particle phosphor, and CdSe / GaP semiconductor fine particle phosphor was produced. These light emitting devices were manufactured using the same method as in Example B1 except for the type of semiconductor fine particle phosphor.

  The luminous efficiency of the obtained light emitting device was confirmed based on the luminous efficiency of the light emitting device of Example B1. The results are shown in Table 8.

<Consideration of relationship between core / shell structure of semiconductor fine particle phosphor and luminous efficiency of light emitting device>
Hereinafter, the influence of the energy band structure of the semiconductor fine particle phosphor having the core / shell structure on the light emission efficiency of the light emitting device will be examined.

  Table 8 shows the luminous efficiency of the light emitting device manufactured using various semiconductor fine particle phosphors. The luminous efficiency of the light emitting device has the same tendency as the luminous efficiency of the semiconductor fine particle phosphor shown in Table 5. Therefore, it can be confirmed that the light emission efficiency is improved also in the light emitting device manufactured using the semiconductor fine particle phosphor of the present invention.

  In addition, not only the semiconductor fine particle phosphor having the InN semiconductor crystal core but also the light emitting device using the semiconductor fine particle phosphor having the InP semiconductor crystal core and the CdSe semiconductor crystal core, it was confirmed that the light emission efficiency was improved.

<Manufacture of image display device>
Image display devices were manufactured and evaluated using the semiconductor fine particle phosphors synthesized in Examples 1 to 5, 7 to 24, and Comparative Examples 1 to 6. In the manufacture of the image display device, a silicone resin SCR-1015 manufactured by Shin-Etsu Chemical Co., Ltd. was used as the silicone resin. Further, a semiconductor light emitting diode element emitting blue light of 450 nm and a semiconductor fine particle phosphor emitting red or green were used as a backlight of an image display device. In addition, the emission color of the backlight was manufactured by appropriately adjusting the amount of the phosphor so that white light emission with a color temperature of 10,000 K was obtained when the color filter was fully opened.

  Note that a light emission measurement system MCPD-7000 manufactured by Otsuka Electronics Co., Ltd. was used to measure the screen brightness of the image display device.

(Example C1: Image display device using InN / GaN semiconductor fine particle phosphor)
In Example C1, using the InN / GaN semiconductor fine particle phosphor synthesized in Example 1, an image display device as shown in FIG. 8 was produced.

  First, an InN / GaN semiconductor fine particle phosphor that emits red or green light was synthesized using the method of Example 1. These two types of InN / GaN semiconductor fine particle phosphors were mixed with about 500 mg of silicone resin A solution. Then, it mixed with about 500 mg of silicone resin B liquid. The obtained silicone resin was filled on the light-emitting element, and heat-cured at 80 ° C. for 1 hour and at 150 ° C. for 5 hours to produce a light-emitting device of Example B1.

(Examples C2 to C5, Comparative Examples C1 to C2: Image display devices using various semiconductor fine particle phosphors)
In Examples C2 to C5 and Comparative Examples C1 to C2, InN / ZnO, InN / AlN, InN / MgO, InN / MgS semiconductor fine particle phosphors and InN semiconductors synthesized in Examples 2 to 5 and Comparative Examples 1 and 2 were used. An image display device using a fine particle phosphor and an InN / ZnS semiconductor fine particle phosphor was produced. The image display devices of Examples C2 to C5 and Comparative Examples C1 to C2 were manufactured using the same method as Example C1 except for the type of semiconductor fine particle phosphor.

  The screen brightness of the obtained image display device was confirmed based on the screen brightness of the image display device of Example C1. The results are shown in Table 9.

(Examples C6 to C14, Comparative Examples C3 to C4: Image display device using semiconductor fine particle phosphor having InP semiconductor crystal core)
In Examples C6 to C14 and Comparative Examples C3 to C4, InP / AlN, InP / AlP, InP / ZnS, InP / ZnSe, InP / MgO, InP / synthesized in Examples 7 to 15 and Comparative Examples 3 to 4 were used. Image display device using semiconductor fine particle phosphor having core / shell structure of MgS, InP / MgSe, InP / 3C-SiC, InP / 6H-SiC, InP semiconductor fine particle phosphor, InP / ZnO semiconductor fine particle phosphor Produced. These image display devices were produced using the same method as in Example C1 except for the type of semiconductor fine particle phosphor.

  The screen brightness of the obtained image display device was confirmed based on the screen brightness of the image display device of Example C6. The results are shown in Table 9.

(Examples C15 to C23, Comparative Examples C5 to C6: Image Display Device Using Semiconductor Fine Particle Phosphor Having CdSe Semiconductor Crystal Core)
In Examples C15 to C23 and Comparative Examples C5 to C6, CdSe / AlN, CdSe / AlP, CdSe / GaN, CdSe / ZnS, CdSe / ZnSe, CdSe / C synthesized in Examples 16 to 23 and Comparative Examples 5 to 6 were used. An image display device using MgO, CdSe / MgS, CdSe / MgSe, CdSe / 6H—SiC semiconductor fine particle phosphor, CdSe semiconductor fine particle phosphor, and CdSe / GaP semiconductor fine particle phosphor was produced. These image display devices were produced using the same method as in Example C1 except for the type of semiconductor fine particle phosphor.

  The screen brightness of the obtained image display device was confirmed based on the screen brightness of the image display device of Example C15. The results are shown in Table 9.

<Consideration of relationship between core / shell structure of semiconductor fine particle phosphor and screen brightness of image display device>
Hereinafter, the influence of the energy band structure of the core / shell structure type semiconductor fine particle phosphor on the screen brightness of the image display device will be examined.

  Table 9 shows the screen brightness of the image display device manufactured using various semiconductor fine particle phosphors. The screen luminance of the image display device shows the same tendency as the luminous efficiency of the semiconductor fine particle phosphor shown in Table 5. Therefore, it can be confirmed that the screen brightness is improved also in the image display device manufactured using the semiconductor fine particle phosphor of the present invention.

  In addition, not only the semiconductor fine particle phosphor having the InN semiconductor crystal core but also the image display device using the semiconductor fine particle phosphor having the InP semiconductor crystal core and the CdSe semiconductor crystal core, it was confirmed that the screen luminance was improved.

  Although the embodiments of the present invention have been described as described above, it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. 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.

  The semiconductor fine particle phosphor in the present invention is expected to be put to practical use in many scenes in the light-related field. Specifically, the wavelength conversion member, the semiconductor light emitting device, and the image display device include a display light source, an alternative light source for a small light bulb, a backlight light source for a liquid crystal panel, general illumination, decorative illumination, a light emitting display device, a display, a projector, etc. Can be used for applications.

  100, 200, 501, 501r, 501g, 501b, 602, 603 Semiconductor fine particle phosphor, 101, 201 Semiconductor crystal core, 102, 202, 203 Shell layer, 103, 204 Modified organic compound, 500 Wavelength conversion member, 502, 606 Translucent material, 503 incident light, 504 emitted light, 600 light emitting device, 601 semiconductor light emitting diode element, 605 frame, 607 semiconductor active layer, 608 p side electrode, 609 n side electrode, 610 n electrode portion, 611 adhesive, 612 p electrode part, 613 metal wire, 700 image display device, 701 light emitting device, 702 emission light, 703 light guide plate, 704 irradiation light, 705 image display part, 800 liquid crystal part, 801a lower polarizing plate, 801b upper polarizing plate, 802 Thin film transistor, 803a Transparent conductive film, 803 b Upper thin film electrode, 804a alignment film, 804b alignment film, 805 liquid crystal layer, 806 color filter.

Claims (25)

A semiconductor fine particle phosphor having a semiconductor crystal core and a shell layer covering the semiconductor crystal core, satisfying the following general formulas (1) and (2):
Ec ′ <Ec (shell) (1)
Ev ′> Ev (shell) (2)
(In the formula, Ec (shell) indicates the energy level at the lower end of the conduction band of the shell layer, Ev (shell) indicates the energy level at the upper end of the valence band of the shell layer, and Ec ′ indicates the inside of the semiconductor fine particle phosphor. Ev ′ represents the quantum level formed by the confinement effect of holes inside the semiconductor fine particle phosphor.
The semiconductor crystal core is made of InN;
A semiconductor fine particle phosphor, wherein the shell layer is made of a compound semiconductor of at least one of GaN and AlN.   The semiconductor fine particle phosphor according to claim 1, wherein the shell layer is made of GaN, and the thickness of the shell layer is 1.1 nm or more.   The semiconductor fine particle phosphor according to claim 1, wherein the shell layer is made of AlN, and the thickness of the shell layer is 0.4 nm or more. A semiconductor fine particle phosphor having a semiconductor crystal core and a shell layer covering the semiconductor crystal core, satisfying the following general formulas (1) and (2):
Ec ′ <Ec (shell) (1)
Ev ′> Ev (shell) (2)
(In the formula, Ec (shell) indicates the energy level at the lower end of the conduction band of the shell layer, Ev (shell) indicates the energy level at the upper end of the valence band of the shell layer, and Ec ′ indicates the inside of the semiconductor fine particle phosphor. Ev ′ represents the quantum level formed by the confinement effect of holes inside the semiconductor fine particle phosphor.
The semiconductor crystal core is made of InN;
A semiconductor fine particle phosphor, wherein the shell layer is made of at least one compound semiconductor selected from the group consisting of ZnO, MgO and MgS. A semiconductor fine particle phosphor having a semiconductor crystal core and a shell layer covering the semiconductor crystal core, satisfying the following general formulas (1) and (2):
Ec ′ <Ec (shell) (1)
Ev ′> Ev (shell) (2)
(In the formula, Ec (shell) indicates the energy level at the lower end of the conduction band of the shell layer, Ev (shell) indicates the energy level at the upper end of the valence band of the shell layer, and Ec ′ indicates the inside of the semiconductor fine particle phosphor. Ev ′ represents the quantum level formed by the confinement effect of holes inside the semiconductor fine particle phosphor.
The semiconductor crystal core is made of InP;
A semiconductor fine particle phosphor, wherein the shell layer is made of at least one compound semiconductor selected from the group consisting of ZnS, ZnSe, and AlP.   The semiconductor fine particle phosphor according to claim 5, wherein the shell layer is ZnS, and the thickness of the shell layer is 0.9 nm or more.   The semiconductor fine particle phosphor according to claim 5, wherein the shell layer is ZnSe, and the thickness of the shell layer is 1.3 nm or more.   The semiconductor fine particle phosphor according to claim 5, wherein the shell layer is AlP, and the thickness of the shell layer is 3.4 nm or more. A semiconductor fine particle phosphor having a semiconductor crystal core and a shell layer covering the semiconductor crystal core, satisfying the following general formulas (1) and (2):
Ec ′ <Ec (shell) (1)
Ev ′> Ev (shell) (2)
(In the formula, Ec (shell) indicates the energy level at the lower end of the conduction band of the shell layer, Ev (shell) indicates the energy level at the upper end of the valence band of the shell layer, and Ec ′ indicates the inside of the semiconductor fine particle phosphor. Ev ′ represents the quantum level formed by the confinement effect of holes inside the semiconductor fine particle phosphor.
The semiconductor crystal core is made of InP;
A semiconductor fine particle phosphor, wherein the shell layer is made of at least one compound semiconductor selected from the group consisting of AlN, MgO, MgS, MgSe, 3C—SiC, and 6H—SiC. A semiconductor fine particle phosphor having a semiconductor crystal core and a shell layer covering the semiconductor crystal core, satisfying the following general formulas (1) and (2):
Ec ′ <Ec (shell) (1)
Ev ′> Ev (shell) (2)
(In the formula, Ec (shell) indicates the energy level at the lower end of the conduction band of the shell layer, Ev (shell) indicates the energy level at the upper end of the valence band of the shell layer, and Ec ′ indicates the inside of the semiconductor fine particle phosphor. Ev ′ represents the quantum level formed by the confinement effect of holes inside the semiconductor fine particle phosphor.
The semiconductor crystal core is made of CdSe;
A semiconductor fine particle phosphor, wherein the shell layer is made of ZnS.   The semiconductor fine particle phosphor according to claim 10, wherein the shell layer has a thickness of 1.0 nm or more. A semiconductor fine particle phosphor having a semiconductor crystal core and a shell layer covering the semiconductor crystal core, satisfying the following general formulas (1) and (2):
Ec ′ <Ec (shell) (1)
Ev ′> Ev (shell) (2)
(In the formula, Ec (shell) indicates the energy level at the lower end of the conduction band of the shell layer, Ev (shell) indicates the energy level at the upper end of the valence band of the shell layer, and Ec ′ indicates the inside of the semiconductor fine particle phosphor. Ev ′ represents the quantum level formed by the confinement effect of holes inside the semiconductor fine particle phosphor.
The semiconductor crystal core is made of CdSe;
A semiconductor fine particle phosphor, wherein the shell layer is made of at least one compound semiconductor selected from the group consisting of AlN, AlP, GaN, ZnSe, MgO, MgS, MgSe, and 6H—SiC.   The semiconductor fine particle phosphor according to any one of claims 1, 4, 5, 9, 10 and 12, wherein a lattice mismatch rate between the semiconductor crystal core and the shell layer is 15% or less.   The semiconductor fine particle phosphor according to any one of claims 1, 4, 5, 9, 10 and 12, wherein the semiconductor crystal core is made of a direct transition type compound semiconductor.   The semiconductor fine particle phosphor according to any one of claims 1, 4, 5, 9, 10 and 12, which emits visible light of 380 nm to 780 nm.   The semiconductor fine particle phosphor according to any one of claims 1, 4, 5, 9, 10, and 12, wherein an average particle diameter of the semiconductor crystal core is not more than twice a Bohr radius. Semiconductor fine particle phosphor according to any one of claims 1 to 16,
A wavelength conversion member comprising a translucent member. Semiconductor fine particle phosphor according to any one of claims 1 to 16,
A light emitting device comprising a light emitting element.   The light emitting device according to claim 18, wherein the light emitting element is a semiconductor light emitting diode element or a semiconductor light emitting laser diode element.   The light emitting device according to claim 18, comprising two or more types of the semiconductor fine particle phosphor. The semiconductor light emitting element emits blue light;
21. The light emitting device according to claim 20, wherein the semiconductor fine particle phosphor contains at least a green light emitting semiconductor fine particle phosphor and a red light emitting semiconductor fine particle phosphor. Semiconductor fine particle phosphor according to any one of claims 1 to 16,
An image display device comprising a light emitting element.   The image display device according to claim 22, comprising two or three types of semiconductor fine particle phosphors.   The image display apparatus according to claim 22, wherein the light emitting element is a semiconductor light emitting diode element, a semiconductor light emitting laser diode element, or an organic electroluminescence element. The semiconductor light emitting element emits blue light;
The image display device according to claim 22, wherein the semiconductor fine particle phosphor contains at least a green light emitting semiconductor fine particle phosphor and a red light emitting semiconductor fine particle phosphor.

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