JP2015086284A - Fluorescent body, wavelength converting member and light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorescent body capable of achieving a light-emitting device improved in visible light transmittance when not in use and to provide a wavelength converting member and a light-emitting device using the same.SOLUTION: There are provided: a fluorescent body which comprises first nanoparticles composed of first semiconductor crystals and second nanoparticles which are bonded to a part of s surface of the first nanoparticles and composed of second semiconductor crystals different from the first semiconductor crystals; and a wavelength converting member and a light-emitting device using the fluorescent body. The first nanoparticles have a volume larger than that of the second nanoparticles and the first semiconductor crystals have a band gap larger than that of the second semiconductor crystals.

Description

  The present invention relates to a phosphor, and a wavelength conversion member and a light emitting device using the phosphor.

  Currently, lighting is used in various ways. For example, the lighting is installed on the ceiling of the room in order to illuminate the entire room with sufficient luminance, or is installed with appropriate luminance in a place where brightness is required. Needless to say, the latter is preferable in terms of energy saving.

  As an illuminating device, one having a light emitting portion (wavelength conversion member) containing phosphor particles that emit fluorescence by absorbing excitation light from a light source is conventionally known. For example, Patent Document 1 discloses a light emitting device and an illumination device including a wavelength conversion film containing a quantum dot phosphor having a core-shell structure.

JP 2013-033833 A

  In an illuminating device including a light emitting unit containing phosphor particles, the phosphor particles absorb light having a shorter wavelength than the emission wavelength. The light absorbed by the phosphor particles generally contains visible light. Therefore, in the above-described lighting device, the visible light transmittance tends to decrease, and it does not look transparent when not in use (the other side is transparent). There was a problem that the lighting was conspicuous and the line of sight was poor, and the surrounding space was felt narrow.

  The above-mentioned problem is particularly remarkable when a quantum dot phosphor having a core-shell structure as described in Patent Document 1 is used as a phosphor particle, or when the phosphor particle is a red phosphor. That is, in the core-shell structure, a relatively large amount of phosphor particles are contained in the wavelength conversion member for sufficient absorption of excitation light due to the particle structure in which excitation light is absorbed by the shell portion and light is emitted by the core portion. There is a need. The greater the phosphor particle content, the lower the visible light transmittance. In addition, since the red phosphor absorbs most of light in the visible region, which is light having a shorter wavelength than the emission wavelength, the transmittance of visible light is particularly likely to decrease when the red phosphor is used.

  The objective of this invention is providing the fluorescent substance which can implement | achieve the light-emitting device with which visible-light transmittance was improved at the time of non-use, and the wavelength conversion member and light-emitting device using the same.

The present invention provides the following phosphor, wavelength conversion member, and light emitting device.
[1] First nanoparticles composed of a first semiconductor crystal;
A second nanoparticle made of a second semiconductor crystal that is bonded to a part of the surface of the first nanoparticle and is different from the first semiconductor crystal;
Including a phosphor.

  [2] The phosphor according to [1], wherein the first nanoparticle has a larger volume than the second nanoparticle, and the first semiconductor crystal has a larger band gap than the second semiconductor crystal. .

  [3] The phosphor according to [1] or [2], wherein one second nanoparticle is bonded to each first nanoparticle.

  [4] The phosphor according to any one of [1] to [3], wherein the first nanoparticles are 10 to 100 nm and the second nanoparticles are 1 to 10 nm.

  [5] The phosphor according to any one of [1] to [4], wherein the first nanoparticles absorb primary light, and the second nanoparticles emit secondary light having a longer wavelength than the primary light.

  [6] The phosphor according to [5], wherein the second nanoparticles are phosphor particles that emit red light.

  [7] A wavelength conversion member including a phosphor layer containing the phosphor according to any one of [1] to [6].

  [8] The wavelength conversion member according to [7], further including a pair of transparent electrodes that sandwich the phosphor layer.

[9] It further includes a phosphor binding layer that forms a bond with the phosphor in the phosphor layer between the phosphor layer and one of the transparent electrodes,
The phosphor in the phosphor layer comprises a first surface modifying molecule that binds to the surface of the first nanoparticle, and a second surface modifying molecule that binds to the surface of the second nanoparticle,
The wavelength conversion according to [8], wherein the phosphor in the phosphor layer and the phosphor binding layer form a bond only through the second surface modification molecule among the first and second surface modification molecules. Element.

  [10] The wavelength conversion member according to [9], wherein the phosphor layer includes a plurality of phosphors having different molecular lengths of the second surface modification molecules.

[11] A phosphor binding layer that forms a bond with the phosphor in the phosphor layer between the phosphor layer and one of the transparent electrodes,
The phosphor in the phosphor layer comprises a third surface modifying molecule that binds to the surface of the first nanoparticle, and a second surface modifying molecule that binds to the surface of the second nanoparticle,
The phosphor in the phosphor layer includes a first phosphor that forms a bond with the phosphor binding layer through the second surface modification molecule, and a first phosphor through the second surface modification molecule. The wavelength conversion member according to [8], including a second phosphor that forms a bond with the third surface modification molecule.

[12] a light source that emits primary light;
The wavelength conversion member according to any one of [7] to [11], which absorbs at least a part of the primary light and emits secondary light;
A light emitting device.

[13] The wavelength conversion member includes a first region and a second region,
The light emitting device according to [12], wherein the magnitude of the electric field applied by the pair of transparent electrodes is different between the first region and the second region.

[14] The wavelength conversion member includes a first region and a second region,
The phosphor according to [12], wherein the phosphor contained in the first region and the phosphor contained in the second region are phosphors that emit light of different colors.

  According to the phosphor and the wavelength conversion member of the present invention, it is possible to provide a light-emitting device that has improved visible light transmittance when not in use, and is inconspicuous when not in use, and can feel a wide surrounding space to be installed. Can do. The light emitting device of the present invention can be suitably used as, for example, a lighting device.

FIG. 1A is a diagram schematically illustrating an example of a phosphor according to the first embodiment of the present invention, and FIG. 1B is a diagram illustrating a case where the phosphor illustrated in FIG. It is an energy band figure which shows a mode that light (light) is absorbed and secondary light (fluorescence) is emitted. It is a figure which shows typically an example of the light-emitting device using the fluorescent substance which concerns on this invention. FIG. 3A is a diagram schematically showing an example of a wavelength conversion member according to the third embodiment of the present invention, and FIG. 3B is a diagram illustrating a case where the phosphor shown in FIG. It is an energy band figure which shows a mode that it absorbs excitation light) and emits secondary light (fluorescence). It is sectional drawing which shows typically an example of the wavelength conversion member which concerns on the 4th Embodiment of this invention. It is sectional drawing which shows typically an example of the wavelength conversion member which concerns on the 5th Embodiment of this invention. It is sectional drawing which shows typically an example of the wavelength conversion member which concerns on the 6th Embodiment of this invention. It is a figure which shows typically an example of the light-emitting device which concerns on the 8th Embodiment of this invention. It is a figure which shows typically an example of the light-emitting device which concerns on the 9th Embodiment of this invention. It is a figure which shows the result of having measured the emitted light intensity about the fluorescent substance A obtained in Example 1, and the fluorescent substance of the comparative example 1. FIG. It is a figure which shows the result of having measured the visible light transmittance | permeability about the wavelength conversion member obtained in Example 3 and Comparative Example 2. FIG. It is a figure which shows the result of having measured the luminescence intensity about the wavelength conversion member obtained in Example 3, Example 4, and Comparative Example 2. FIG.

Hereinafter, the present invention will be described in detail with reference to embodiments.
<First Embodiment>
FIG. 1A is a diagram schematically showing an example of the phosphor according to the present embodiment. FIG. 1B is a diagram in which the phosphor shown in FIG. 1A absorbs primary light (excitation light). It is an energy band figure which shows a mode that secondary light (fluorescence) is emitted. FIG. 2 is a diagram schematically showing an example of a light emitting device using the phosphor according to the present embodiment. As shown in FIG. 1A, the present invention relates to a phosphor formed by bonding first nanoparticles 10 and second nanoparticles 20.

  The phosphor 1 shown in FIG. 1A includes a first nanoparticle 10 made of a first semiconductor crystal and a second semiconductor that is bonded to a part of the surface of the first nanoparticle 10 and is different from the first semiconductor crystal. It is comprised with the 2nd nanoparticle 20 consisting of a crystal | crystallization. The phosphor 1 absorbs the primary light (excitation light) 30 by the first nanoparticles 10, changes the absorbed energy (carriers generated thereby) to the second nanoparticles 20, and changes the second nanoparticles 20 from the second nanoparticles 20. Next light (fluorescence) 40 is emitted [see FIGS. 1A and 1B]. The secondary light 40 usually has a longer wavelength than the primary light 30.

  In order to realize the energy transition as shown in FIG. 1B, the first semiconductor crystal constituting the first nanoparticle 10 is usually more bandgap (2) than the second semiconductor crystal constituting the second nanoparticle 20. Increase the energy gap. In general, the volume of the first nanoparticles 10 is larger than the volume of the second nanoparticles 20.

  Unlike the structure in which the entire surface of the core portion is covered with the shell portion as in the conventional core-shell structure, the phosphor 1 has the granular second nanoparticles 20 bonded to a part of the surface of the first nanoparticles 10. This is one feature.

  By making the volume of the first nanoparticle 10 larger than the volume of the second nanoparticle 20, the primary light (excitation light) 30 can be efficiently absorbed, whereby the second nanoparticle 20 emits light efficiently. Can be made. Thus, while the volume of the 1st nanoparticle 10 is made comparatively large, it is set as the structure joined to the granular 2nd nanoparticle 20 in a part of the surface, Therefore The 1st nanoparticle 10 and the 2nd nanoparticle 20 are used. Can be made smaller than the conventional core-shell structure. By reducing the bonding area, stress generated by strain based on lattice mismatch can be reduced and generation of defects in the crystal can be suppressed, so that light emission efficiency can be improved.

  Thus, according to the phosphor 1, the volume of the second nanoparticles 20 responsible for light emission can be reduced while ensuring good light emission efficiency. Thereby, since visible light absorption by the second nanoparticles 20 can be reduced, a wavelength conversion member and a light emitting device having high visible light transparency can be realized.

  More specifically, the light emitting device includes, for example, as shown in FIG. 2, a light source 50 that emits primary light 30 and a phosphor 1 that emits secondary light 40 by absorbing at least part of the primary light 30. However, when the phosphor 1 according to the present invention is used when the light-emitting device is not used, visible light 70 of the wavelength conversion member 60 containing the wavelength conversion member 60 can be obtained. Since the visible light 70 ′ transmitted through the wavelength conversion member 60 can be increased, the other side can be seen well. According to such a light-emitting device with a good line of sight, there is no feeling of pressure even when it is arranged in a space to be used. The effect of the present invention is particularly high when the second nanoparticles 20 are phosphor particles emitting red light that can absorb most of light in the visible region.

  The “nano” in the first nanoparticle 10 and the second nanoparticle 20 means that the particle size is nano-order (within a range of about 1 to 100 nm), and such nanoparticles are used. Thereby, scattering of visible light 70 on the particle surface can also be suppressed. Moreover, since the scattering of the primary light 30 on the particle surface can be suppressed, the primary light 30 can be efficiently absorbed by the first nanoparticles 10.

  The first semiconductor crystal constituting the first nanoparticle 10 is preferably a material that can efficiently absorb the primary light 30 and can efficiently absorb blue light (light from the blue light emitting element) as the primary light 30. It is more preferable that The first semiconductor crystal can be, for example, InGaN that can efficiently absorb blue light.

  Since the 1st nanoparticle 10 is a particle which plays the role which absorbs the primary light 30, it is preferable to make a volume larger than the 2nd nanoparticle 20 as mentioned above. From such a viewpoint, the particle size of the first nanoparticles 10 is preferably in the range of 10 to 100 nm, and more preferably in the range of 20 to 50 nm. The particle diameters of the first nanoparticles 10 and the second nanoparticles 20 are measured by a transmission electron microscope (TEM).

  The second semiconductor crystal constituting the second nanoparticle 20 is a material different from the first semiconductor crystal, and is preferably a phosphor material that can emit visible light efficiently. An example of such a crystal material is a group 13 nitride. The group 13 nitride is a compound in which a group 13 element (B, Al, Ga, In, Tl) and a nitrogen element (N) are bonded. The second semiconductor crystal may contain only one type of group 13 element or may contain two or more types. Specific examples of the crystal material are InN, AlInN, and AlGaInN, and preferably InN.

  The band gap of the second semiconductor crystal is smaller than that of the first semiconductor crystal, specifically, it is preferably in the range of 1.8 to 2.8 eV. When the second nanoparticle 20 is used as a red phosphor, the band gap of the second semiconductor crystal is preferably in the range of 1.85 to 2.5 eV, and when used as a green phosphor, 2.3 to 2.5 eV. When used as a blue phosphor, it is preferably in the range of 2.65 to 2.8 eV.

  The particle size of the second nanoparticles 20 is preferably smaller than the particle size of the first nanoparticles 10, more preferably in the range of 1 to 10 nm, and even more preferably in the range of 2 to 5 nm. When the particle size is within this range, excitation energy can be efficiently converted into visible light emission. The color of the secondary light 40 from the second nanoparticles 20 can be set to a desired color within the range of red to blue by adjusting the particle size and composition of the second nanoparticles 20.

  The number of the second nanoparticles 20 bonded to the surface of the first nanoparticles 10 is not particularly limited, and the second nanoparticles 20 per one first nanoparticle 10 as in the example of FIG. May be bonded, or two or more second nanoparticles 20 may be bonded. However, from the viewpoint of reducing the bonding area between the first nanoparticle 10 and the second nanoparticle 20 and the viewpoint of reducing the volume of the second nanoparticle 20, the second nanoparticle per one first nanoparticle 10. A structure in which one 20 is joined is preferable. In addition, when two or more second nanoparticles 20 are bonded to one first nanoparticle 10, if the second nanoparticles 20 are close to each other, self-absorption (the emitted light is emitted from the second nanoparticle). There is a possibility that the light emission efficiency is lowered by the phenomenon that 20 absorbs. Therefore, even in view of this point, a structure in which one second nanoparticle 20 is joined per one first nanoparticle 10 is preferable.

  Furthermore, in the wavelength conversion member which concerns on the 3rd-6th embodiment mentioned later, the fluorescent substance 1 needs to have anisotropy regarding the shape, Therefore, with respect to one 1st nanoparticle 10, When two or more second nanoparticles 20 are bonded together, there is a restriction that two or more second nanoparticles 20 are bonded at positions where anisotropy occurs in the shape.

  The number of second nanoparticles 20 bonded per one first nanoparticle 10 can be confirmed by a transmission electron microscope (TEM).

  In the phosphor 1, the first nanoparticle 10 and the second nanoparticle 20 are bonded by an epitaxial junction, and the first semiconductor crystal constituting the first nanoparticle 10 and the second semiconductor constituting the second nanoparticle 20. At the interface with the crystal, the crystal structure is inherited and bonded.

  Although the manufacturing method in particular of the fluorescent substance 1 is not restrict | limited, For example, it can manufacture by the following method. First, the first nanoparticles 10 are prepared. The first nanoparticles 10 can be prepared, for example, by liquid phase synthesis. Specifically, a raw material for forming the first semiconductor crystal (in the case of InGaN, for example, indium iodide, gallium iodide and sodium amide) is mixed with a solvent and reacted at a temperature of about 180 to 500 ° C. The particle size of the first nanoparticles 10 to be generated can be controlled by the reaction time or the like. The longer the reaction time, the larger the grain growth. Therefore, the first nanoparticles 10 can be controlled to have a desired particle size by growing the grains while monitoring using methods such as photoluminescence, light absorption, and dynamic light scattering.

  Next, a small amount of a source material (for example, tris (dimethylamino) indium in the case of InN) is added to the liquid containing the first nanoparticles 10 and heated to react. By this reaction, the second semiconductor crystal takes over the crystal structure of the first semiconductor crystal constituting the first nanoparticle 10 and grows in the form of particles on the surface of the first nanoparticle 10, so that the second nanoparticle 20 is formed. It is formed.

<Second Embodiment>
With reference to FIG. 2, the present embodiment relates to a wavelength conversion member 60 containing the phosphor 1 described above. The wavelength conversion member 60 is a member including or made of a phosphor layer in which the phosphor 1 is dispersed, and the phosphor layer is composed of the phosphor 1 and a sealing member that disperses and fixes the phosphor layer. Can do.

  The sealing member has translucency and is preferably transparent. Thereby, since the wavelength conversion member 60 can be made translucent when not in use, it is advantageous in that the wavelength conversion member 60 and a light emitting device using the wavelength conversion member 60 are difficult to stand out. The term “transparent” means that the visible light transmittance is 80% or more. Although it does not restrict | limit especially as a material which comprises a sealing member, For example, translucent (transparent) resin, such as acrylic resin and a silicone resin, a glass material etc. can be used. Especially, since the dispersibility of the fluorescent substance 1 is favorable, it is preferable to use an acrylic resin.

  The phosphor layer may include only one type of phosphor 1 or may include two or more types of phosphors 1 that differ in material composition, particle size, and the like. For example, two or more types of phosphors 1 having different emission colors can be included (for example, a red phosphor and a green phosphor).

  The volume ratio of the phosphor 1 and the sealing member in the phosphor layer is preferably 0.0001: 1 to 1:10. When the volume ratio is within this range, the phosphor 1 is easily dispersed uniformly in the sealing member without accompanying the aggregation of the phosphor 1.

  The outer shape of the wavelength conversion member 60 and the phosphor layer is not particularly limited, and may be an appropriate shape including a rectangular shape such as a rectangular parallelepiped or a cube, a cylindrical shape, or the like. By irradiating at least a part of the outer surface of the wavelength conversion member 60 with the primary light (excitation light) 30, secondary light (fluorescence) 40 emitted from the phosphor 1 can be extracted from the other part of the outer surface. .

<Third Embodiment>
Fig.3 (a) is a figure which shows typically an example of the wavelength conversion member which concerns on this embodiment, FIG.3 (b) shows the primary light (excitation light) by the fluorescent substance shown by Fig.3 (a). It is an energy band figure which shows a mode that it absorbs and emits secondary light (fluorescence). The wavelength conversion member 60 of the present embodiment includes a pair of transparent electrodes that sandwich the phosphor layer, and is configured so that an external electric field can be applied to the phosphor layer by applying a voltage between the transparent electrodes. Except for this, it is the same as the second embodiment.

  By placing the phosphor 1 in the phosphor layer in an external electric field in a certain direction, the carriers generated in the first nanoparticles 10 by absorbing the primary light 30 as shown in FIG. It is possible to cause the band to tilt in a direction that facilitates transition to the nanoparticles 20. Thereby, the luminous efficiency of the phosphor 1 can be further improved. The carriers generated in the first nanoparticles 10 are spatially spread and exist in the first nanoparticles 10 having a large volume. However, by applying an external electric field, the carriers are quickly transferred to the second nanoparticles 20 responsible for light emission. Can be moved.

In order to generate the band inclination, it is important to satisfy the following points.
[A] A phosphor 1 having anisotropy in shape is used.
[A] In the phosphor layer, the phosphors 1 are arranged so that the directions of the phosphors 1 are aligned.
[C] The arrangement direction of the phosphors 1 and the application direction of the external electric field are aligned.

  With respect to [a] above, for example, the phosphor 1 in which one second nanoparticle 20 is bonded to one first nanoparticle 10 as shown in FIG. 3A has anisotropy. doing. In the phosphor in which two second nanoparticles 20 are bonded to one first nanoparticle 10, two second nanoparticles are located at point-symmetric positions with respect to the center of the first nanoparticle 10. It is isotropic when the particles 20 are joined, but otherwise has anisotropy.

  With respect to [A] and [C] above, the upstream side of the external electric field (the negative electrode transparent electrode side) is the first in order to cause the band to tilt in such a direction that the carrier easily transitions to the second nanoparticles 20. It is preferable to arrange the phosphors 1 in such an orientation that the nanoparticles 10 are formed and the downstream side (positive electrode transparent electrode side) is the second nanoparticles 20.

  As the transparent electrode, for example, materials such as indium tin oxide, zinc oxide, tin oxide, and titanium oxide can be used.

<Fourth Embodiment>
FIG. 4 is a cross-sectional view schematically showing an example of the wavelength conversion member according to the present embodiment. The wavelength conversion member 60 of the present embodiment includes a pair of transparent electrodes 80 and 80 that sandwich the phosphor layer, and an external electric field is applied to the phosphor layer by applying a voltage between the transparent electrodes 80 and 80. It is the same as that of the said 3rd Embodiment by the point comprised so that it can do, and there can exist the same effect.

  In the present embodiment, a phosphor binding layer 90 is provided between the phosphor layer and one of the transparent electrodes 80, and the phosphor 1 in order to bind the phosphor 1 in the phosphor layer to the phosphor binding layer 90. A predetermined surface modifying molecule (ligand) is bonded to the surface of the substrate.

  The phosphor 1 in the phosphor layer is forcibly bonded to the phosphor binding layer 90 disposed at one end of the phosphor layer in a predetermined orientation by using a surface modifying molecule, thereby simply sealing the phosphor 1. It is possible to easily realize the above-mentioned [A] and [C] configurations that are difficult to realize simply by being dispersed in the stop member.

  In this embodiment, as the phosphor 1, the first surface modification molecule 11 and the second surface modification molecule 21 are bonded (coordinated) to the phosphor composed of the first and second nanoparticles 10 and 20 having anisotropy. Use the same thing. As shown in FIG. 4, the first surface modification molecule 11 is bonded to the surface of the first nanoparticle 10, and the second surface modification molecule 21 is bonded to the surface of the second nanoparticle 20.

  The first surface modification molecule 11 is a molecule that forms a bond only with the phosphor 1 and does not bond with the phosphor binding layer 90. Examples of such molecules include monofunctional amines or thiols. The first surface modification molecule 11 is preferably a molecule having an amino group or a thiol group at the molecular end, and specific examples thereof include 1-aminobutane, 1-aminopentane, 1-aminohexane, 1-aminoheptane, 1 1-aminoalkane such as aminooctane, 1-aminononane, 1-aminodecane, 1-aminohexadecane; aniline; 1-butanethiol, 1-pentanethiol, 1-hexanethiol, 1-heptanethiol, 1-octanethiol 1-alkanethiol, such as 1-nonanethiol, 1-decanethiol, 1-hexadecanethiol; The 1st surface modification molecule | numerator 11 can be couple | bonded with the 1st nanoparticle 10 surface of the fluorescent substance 1 through an amino group or a thiol group.

  The second surface modification molecule 21 is a molecule that forms a bond with both the phosphor 1 and the phosphor binding layer 90. Examples of such molecules include bifunctional amines or thiols. The second surface modification molecule 21 is preferably a molecule having an amino group or a thiol group at both ends of the molecule, and specific examples thereof include 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane. 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, diaminoalkanes such as 1,16-diaminohexadecane; 1,4-diaminobenzene; 1,4 -Butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,7-heptanedithiol, 1,8-octanedithiol, 1,9-nonanedithiol, 1,10-decanedithiol, 1,16- Alkanedithiols such as hexadecanedithiol; 1,4-benzenedithiol. The second surface modification molecule 21 can be bonded to the surface of the second nanoparticle 20 of the phosphor 1 via one amino group or thiol group, and the phosphor binding layer via the other amino group or thiol group. A bond with 90 can be formed.

  The phosphor binding layer 90 is a layer that can form a bond with the functional group of the second surface modification molecule 21, and can be, for example, a layer made of an organic polymer such as an acrylic resin, a layer made of silica gel, or the like. When these materials are used, the bond between the phosphor binding layer 90 and the second surface modification molecule 21 is a hydrogen bond.

  In the phosphor 1 having the first and second surface modification molecules 11 and 21, the phosphor binding layer 90 and the second nanoparticles 20 are arranged in the phosphor layer so that the first and second surface modification molecules 11 and 21 are included. Among them, the phosphors 1 are arranged through the second surface modification molecules 21 only so that the directions of the respective phosphors 1 are aligned. The orientation is such that the phosphor binding layer 90 side becomes the second nanoparticle 20. Therefore, by applying an external electric field in the direction from the transparent electrode on the opposite side of the phosphor-binding layer 90 to the transparent electrode on the phosphor-binding layer 90 side, the same effect as in the third embodiment can be obtained. Is.

  The phosphor 1 having the first and second surface modification molecules 11 and 21 can be produced, for example, by the following method. First, the first nanoparticles 10 are prepared by the method described above. Next, a small amount of a raw material for forming the second semiconductor crystal is added to the obtained liquid containing the first nanoparticles 10, and the first surface modifying molecules 11 are added and heated to react. Next, the second surface modification molecule 21 is added to the liquid containing the phosphor 1 having the first surface modification molecule 11 and mixed by heating.

  Further, the wavelength conversion member 60 according to the present embodiment, that is, the second nanoparticles 20 and the phosphor binding layer 90 in the phosphor 1 in the phosphor layer form a bond only through the second surface modification molecules 21. The wavelength conversion member 60 is formed by applying a coating liquid containing the sealing member and the phosphor 1 on the phosphor binding layer 90 formed on one surface of the transparent electrode 80. At this time, the second surface modification molecule 21 of the phosphor 1 forms a bond with the phosphor binding layer 90 by, for example, hydrogen bonding. Finally, the wavelength conversion member 60 is obtained by forming the other transparent electrode 80 on the surface facing the phosphor binding layer 90.

<Fifth Embodiment>
FIG. 5 is a cross-sectional view schematically showing an example of the wavelength conversion member according to the present embodiment. The wavelength conversion member 60 of the present embodiment has the same configuration as that of the fourth embodiment except that the phosphor layer includes phosphors having different molecular lengths of the second surface modification molecules 21. In the example shown in FIG. 5, the phosphor layer includes a phosphor having the second surface modification molecule 21a having the longest molecular length, a phosphor having the second surface modification molecule 21b having a medium molecular length, and the longest molecular length. And a phosphor having the second second surface modification molecule 21c.

  In the present invention, in view of transparency when a light emitting device is used, for example, in the case where an LED device is used as a light source that emits primary light 30, the light source is provided on the side surface of the wavelength conversion member 60, that is, the transparent electrode 80. It is preferable that the primary light is incident from a surface that does not have the surface. In this case, the phosphor layers have different distances from the phosphor binding layer 90 to the first nanoparticles 10 by making the molecular lengths of the second surface modification molecules 21 of the phosphor 1 different as in this embodiment. If the configuration including the phosphor 1 is used, the number of the phosphors 1 hidden behind the other phosphors 1 is reduced as compared with the case where only the phosphor 1 having the second surface modification molecule 21 having the same molecular length is used. Therefore, the primary light 30 can be more efficiently incident on the phosphor 1 in the phosphor layer (see FIG. 5). Moreover, since it becomes possible to disperse | distribute the fluorescent substance 1 uniformly over the whole fluorescent substance layer, uniform light emission over the whole fluorescent substance layer is attained.

  The primary light 30 from the light source can be incident from the surface having the transparent electrode 80. Even in this case, according to the present embodiment, since the phosphor 1 is uniformly dispersed over the entire phosphor layer, uniform light emission over the entire phosphor layer is possible.

  The molecular length of the second surface modification molecule 21 can be adjusted by changing the carbon number of the carbon chain (for example, alkyl chain) constituting the molecule.

<Sixth Embodiment>
FIG. 6 is a cross-sectional view schematically showing an example of the wavelength conversion member according to the present embodiment. Like the wavelength conversion member 60 of the present embodiment, one or more phosphors 1 can be further linked to the phosphor 1 that binds to the phosphor binding layer 90 by using surface modification molecules. . According to such a configuration, the phosphor 1 can be uniformly dispersed throughout the phosphor layer. Moreover, since the emission intensity of the secondary light (fluorescence) can be further increased, a wavelength conversion member with higher brightness can be realized.

  In order to enable the phosphors 1 to be linked to each other, a diamine molecule, preferably a molecule having an amino group at both ends, is bound as the second surface modification molecule 21 and is bound to the surface of the first nanoparticle 10. As a surface modification molecule (third surface modification molecule 15), instead of the first surface modification molecule 11, a molecule having an amino group and a carboxyl group, preferably an amino group at one end and a carboxyl group at the other end A phosphor 1 to which a molecule having s is bonded may be used. By using such a surface modification molecule, a dehydration condensation reaction (amide) between the carboxyl group of the third surface modification molecule 15 of the phosphor 1 and the amino group of the second surface modification molecule 21 of the other phosphor 1 is achieved. The phosphors 1 can be connected to each other.

  FIG. 6 shows a first phosphor that forms a bond with the phosphor-binding layer 90 via the second surface modification molecule 21, and a third phosphor of the first phosphor via the second surface modification molecule 21. A second phosphor that forms a bond with the surface modifying molecule 15, and a third phosphor that forms a bond with the third surface modifying molecule 15 of the second phosphor through the second surface modifying molecule 21; An example including is shown.

  Also in the present embodiment, the phosphor layer can include the phosphors 1 having different molecular lengths of the second surface modification molecule 21 or the third surface modification molecule 15 as in the fifth embodiment.

<Seventh Embodiment>
Referring to FIG. 2, the present embodiment includes a light source 50 that emits primary light (excitation light) 30 and the above-described phosphor 1 that absorbs at least part of the primary light 30 and emits secondary light (fluorescence). The present invention relates to a light emitting device including a wavelength conversion member 60 contained therein. Since the light-emitting device of this embodiment contains the phosphor 1 according to the present invention, the light-emitting device exhibits high luminous efficiency and excellent visible light transmittance. The wavelength conversion member 60 may be any of the second to sixth embodiments.

  The light source (excitation light source) 50 emits primary light 30 absorbed by the first nanoparticles 10. The primary light 30 has an emission peak wavelength that overlaps at least partially with the absorption wavelength of the first nanoparticle 10. As the light source 10 that emits the primary light 30, a light source having an emission wavelength from the ultraviolet region to the blue region can be preferably used. For example, a light emitting diode (LED) or a laser diode (LD) is used. Can do. Moreover, an organic electroluminescence light emitting element, an inorganic electroluminescence light emitting element, etc. may be used. As the LED or LD, for example, a GaN-based LED or LD can be suitably used. Only one light source 50 may be used, or two or more light sources 50 may be used in combination.

<Eighth Embodiment>
FIG. 7 is a diagram schematically illustrating an example of the light emitting device according to the present embodiment. In the light emitting device of the present embodiment, the wavelength conversion member 60 includes a pair of transparent electrodes that sandwich the phosphor layer, and an external electric field can be applied to the phosphor layer by applying a voltage between the transparent electrodes. However, the wavelength conversion member 60 is divided into a plurality of regions, and the magnitude of the external electric field applied by a pair of transparent electrodes in each region is similar to the third to sixth embodiments. It is characterized in that it can be made different.

  In the example of FIG. 7, the wavelength conversion member 60 is divided into a first region 61 that is the middle region and a second region that is the other region. Therefore, in the light emitting device of FIG. 7, the luminance of light emission in the first region 61 and the second region 62 is made different by changing the magnitude of the external electric field applied to the first region 61 and the second region 62. Can be generated. For example, the luminance of light emitted from the first region 61 can be increased by increasing the external electric field in the first region 61. Of course, it is possible to apply an external electric field to one of the regions while not applying an external electric field to any other region. By utilizing such contrast, it is possible to draw characters and designs on the light-emitting device, and not only the lighting device but also a display device can be used.

  The magnitude of the external electric field applied to each divided region can be easily controlled by incorporating a TFT (thin film transistor) in each divided region.

<Ninth Embodiment>
FIG. 8 is a diagram schematically illustrating an example of the light emitting device according to the present embodiment. The light emitting device of the present embodiment is characterized in that the wavelength conversion member 60 includes a plurality of regions that exhibit different emission colors. In the example of FIG. 8, the wavelength conversion member 60 is divided into four regions, a first region 60a, a second region 60b, a third region 60c, and a fourth region 60d, each emitting secondary light of a different color. . However, it is not restricted to such a specific aspect, The light-emitting device concerning this embodiment should just contain the 2 or more area | region which shows a different luminescent color.

  In order to make the emission colors different, the particle size and composition of the phosphor 1, particularly the second nanoparticles 20 may be adjusted as described above.

  In addition, in order to improve the design and display performance, in combination with the above eighth embodiment, one region is further divided, and the contrast is generated by changing the magnitude of the external electric field between the divided regions. You may make it make it.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these Examples.

<Example 1>
Is a raw material for forming the first semiconductor crystal, indium iodide of 3 mmol, gallium iodide of 7 mmol, and sodium amide 50 mmol, was mixed with 1-octadecene, and subjected to thermal decomposition reaction at 200 ° C., an In _0.3 First nanoparticles made of Ga _0.7 N were prepared (particle size 20 nm). Next, 0.2 mmol of tris (dimethylamino) indium, which is a raw material for forming the second semiconductor crystal, is added to the obtained liquid containing the first nanoparticles and reacted at 200 ° C. Phosphor A was obtained by forming second nanoparticles (particle size 5 nm) made of InN bonded to the surfaces of the nanoparticles.

  The particle size of the first and second nanoparticles was measured using a transmission electron microscope (TEM) (the same applies hereinafter). When the obtained phosphor A was observed using a transmission electron microscope (TEM), the number of second nanoparticles joined to the first nanoparticles was mainly one per first nanoparticle. there were. For the phosphor A, a blue light emitting element made of a group 13 nitride can be used as an excitation light source, and particularly, 450 nm light having a high external quantum efficiency can be efficiently absorbed. In addition, the second nanoparticles made of InN were able to exhibit red light emission because the particle size was adjusted so that the emission wavelength was 620 nm.

<Example 2>
Is a raw material for forming the first semiconductor crystal, indium iodide of 3 mmol, gallium iodide of 7 mmol, and sodium amide 50 mmol, was mixed with 1-octadecene, and subjected to thermal decomposition reaction at 200 ° C., an In _0.3 First nanoparticles made of Ga _0.7 N were prepared (particle size 20 nm). Next, 0.2 mmol of tris (dimethylamino) indium, which is a raw material for forming the second semiconductor crystal, is added to the obtained liquid containing the first nanoparticles, and 10 mmol of the first surface modification molecule is added. By adding 1-hexadecanethiol and reacting at 200 ° C., second nanoparticles (particle size 5 nm) composed of InN bonded to the surface of the first nanoparticles are formed, and on the surface of the first nanoparticles. A first surface modification molecule was attached. Subsequently, 0.2 mmol of 1,6-diaminohexane, which is the second surface modification molecule, is added to the liquid containing the phosphor having the first surface modification molecule, and the reaction is performed at 150 ° C. A phosphor B in which the first surface modification molecule was bonded to the surface of the nanoparticle and the second surface modification molecule was bonded to the surface of the second nanoparticle was obtained.

  When the obtained phosphor B was observed by the same method as in Example 1, the number of second nanoparticles bonded to the first nanoparticles was mainly one per first nanoparticle. For the phosphor B, a blue light emitting element made of a group 13 nitride can be used as an excitation light source, and particularly, 405 nm light having a high external quantum efficiency can be efficiently absorbed. In addition, the second nanoparticles made of InN were able to exhibit red light emission because the particle size was adjusted so that the emission wavelength was 620 nm.

<Comparative Example 1>
A commercial product of a quantum dot phosphor having a core-shell structure was prepared. The core part is made of CdSe, and its particle size is 3 nm. The shell portion is made of ZnS and has a film thickness of 20 nm. This phosphor can also use a blue light emitting element made of a group 13 nitride as an excitation light source, can absorb 405 nm light, and emits red light.

  With respect to the phosphor A obtained in Example 1 and the phosphor of Comparative Example 1, the emission intensity of light having a wavelength of 620 nm using a fluorescence spectrophotometer manufactured by Horiba (manufactured by Jobibain) [a. u. (Arbitrary unit)] was measured. The results are shown in FIG. The emission intensity of Example 1 was 70, and the emission intensity of Comparative Example 1 was 20.

<Example 3>
A rectangular parallelepiped wavelength conversion member in which 1 part by weight of the phosphor A of Example 1 was dispersed in 100 parts by weight of an acrylic resin as a sealing member was produced.

<Comparative Example 2>
A wavelength conversion member having the same shape as in Example 3 was produced in which 10 parts by weight of the phosphor of Comparative Example 1 was dispersed in 100 parts by weight of an acrylic resin as a sealing member. The reason why the amount of the phosphor is 10 parts by weight is that the emission intensity of the light having a wavelength of 620 nm as the wavelength conversion member is the same as that of the third embodiment.

  About the wavelength conversion member obtained in Example 3 and Comparative Example 2, the visible light transmittance when not in use (when not lit) was measured using a spectrophotometer. The results are shown in FIG. The visible light transmittance of Example 3 was 80%, and the visible light transmittance of Comparative Example 2 was 20%.

<Example 4>
A layer made of silica gel as a phosphor binding layer was formed on the layer made of indium tin oxide as the transparent electrode. Next, a coating liquid containing 100 parts by weight of an acrylic resin as a sealing member and 1 part by weight of the phosphor B of Example 2 was prepared, and this was applied to the phosphor binding layer to form a phosphor layer ( The same shape as the wavelength conversion member of Example 3 and Comparative Example 2) was formed. Furthermore, a layer made of indium tin oxide as an opposing transparent electrode was formed on the phosphor layer to obtain a wavelength conversion member.

  About the wavelength conversion member obtained in Example 3, Example 4, and Comparative Example 2, the emission intensity of light having a wavelength of 620 nm using a fluorescent spectrophotometer manufactured by Horiba (manufactured by Jobibainbon) [a. u. (Arbitrary unit)] was measured. The results are shown in FIG. The emission intensity of Example 3 was 70, the emission intensity of Example 4 was 90, and the emission intensity of Comparative Example 2 was 20. Here, the emission intensity of Example 4 is a numerical value when an external electric field (100 V, the transparent electrode on the phosphor binding layer side was used as a positive electrode) was applied to the phosphor layer.

  DESCRIPTION OF SYMBOLS 1 Phosphor, 10 1st nanoparticle, 11 1st surface modification molecule | numerator, 15 3rd surface modification molecule | numerator, 20 2nd nanoparticle, 21, 21a, 21b, 21c 2nd surface modification molecule | numerator, 30 Primary light (excitation light) 40 secondary light (fluorescence), 50 light source, 60 wavelength conversion member, 60a, 61 first region of wavelength conversion member, 60b, 62 second region of wavelength conversion member, 60c third region of wavelength conversion member, 60d wavelength 4th area | region of a conversion member, 70 visible light, visible light which permeate | transmitted 70 'wavelength conversion member, 80 transparent electrode, 90 fluorescent substance coupling layer.

Claims (5)

First nanoparticles comprising a first semiconductor crystal;
A second nanoparticle made of a second semiconductor crystal that is bonded to a part of the surface of the first nanoparticle and is different from the first semiconductor crystal;
Including a phosphor.   2. The phosphor according to claim 1, wherein the first nanoparticles have a volume larger than that of the second nanoparticles, and the first semiconductor crystal has a band gap larger than that of the second semiconductor crystal.   The wavelength conversion member containing the fluorescent substance layer containing the fluorescent substance of Claim 1 or 2.   The wavelength conversion member according to claim 3, further comprising a pair of transparent electrodes that sandwich the phosphor layer. A light source that emits primary light;
The wavelength conversion member according to claim 3 or 4, which absorbs at least a part of the primary light and emits secondary light;
A light emitting device.

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