Wavelength conversion body and wavelength conversion material using the same

Abstract

To provide a wavelength conversion body having improved absorption rate to blue light and improved light extraction efficiency after wavelength conversion.SOLUTION: The wavelength conversion body includes, as semiconductor nanoparticles, first semiconductor nanoparticles for converting light of a wavelength 450 nm into light of a wavelength λ1 nm, and second semiconductor nanoparticles for converting light of a wavelength 450 nm into light of a wavelength λ2 nm. The wavelength λ1 and the wavelength λ2 satisfy λ1>λ2>450. I1a<I1b is satisfied by a relation between an emission intensity I1b at the wavelength λ1 when the wavelength conversion body including the first semiconductor nanoparticle and the second semiconductor nanoparticle is irradiated with light of the wavelength 450 nm and an excitation light quantum number N0 and an emission intensity I1a at the wavelength λ1 when the wavelength conversion body including only the first semiconductor nanoparticles as semiconductor nanoparticle is irradiated with light of the wavelength 450 nm and the excitation light quantum number N0.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wavelength converter and a wavelength conversion material using the same.

Background Art

[0002] In semiconductor particles with a nanosize particle diameter, excitons generated by light absorption are confined in a nanosize space, so that the energy levels of the semiconductor nanoparticles become discrete, and their band gaps depend on the particle diameter. For this reason, the fluorescence emission of semiconductor nanoparticles is highly efficient, and its emission spectrum is sharp. In addition, it has the characteristic that the emission wavelength can be controlled due to the change in the band gap depending on the particle diameter, and it is expected to be applied as a wavelength conversion material for solid-state lighting and displays (Patent Document 1).

[0003] Semiconductor nanoparticles containing Cd are cited as quantum dots exhibiting excellent fluorescence emission characteristics. However, since Cd is highly toxic to the human body and the environment, its use is restricted worldwide, starting with the RoHS directive of the European Union. Therefore, semiconductor nanoparticles that do not contain toxic substances such as Cd are being studied. As one of the alternative materials, the development of semiconductor nanoparticles with InP as the emission center is underway.

[0004] In addition, as a wavelength conversion material using semiconductor nanoparticles, material development for color filter applications has been advanced by patterning a resin composition in which semiconductor nanoparticles and a resin are mixed on a transparent substrate to form a wavelength conversion layer. A color filter in a conventional liquid crystal display is a thin film type optical component in which blue, green, and red pixel portions with a size of several tens to several hundreds of micrometers per pixel are regularly arranged on a transparent substrate, and a black matrix is arranged between the pixels to prevent color mixing between the pixels. The color filter enables image display in fine pixel units by extracting three lights of red, green, and blue from white light.

[0005] When semiconductor nanoparticles are used for color filter applications, in one form, a wavelength conversion layer composed of semiconductor nanoparticles that emit green or red light and a resin is regularly arranged and combined with a blue light source to fabricate a light-emitting element. With such a structure, it becomes possible to convert blue light, which is the excitation light, into green or red light in each wavelength conversion layer. Due to the narrow emission half-width and high conversion efficiency of semiconductor nanoparticles, an improvement in the color reproducibility and luminance of the display is expected.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, if the absorption rate of semiconductor nanoparticles for blue light is not sufficient, the light extraction efficiency of green and red light decreases, and furthermore, blue light passes through the wavelength conversion layer, resulting in color mixing. When such color mixing occurs, there is a limit to the reproducibility of the color to be extracted, so the image quality is inferior, and as a result, the color purity of the color filter decreases.

[0008] In applications such as color filters, when the thickness of the wavelength conversion layer is about 10 μm, many semiconductor nanoparticles cannot be arranged in the optical path, so a material with a high absorption rate for excitation light is required. Furthermore, if the absorbed excitation light can be converted with high efficiency, the light extraction efficiency from the wavelength conversion layer to the outside is improved, and it becomes a wavelength conversion material with excellent light-emitting characteristics.

[0009] Semiconductor nanoparticles with InP as the light-emitting center are known to have a lower absorption coefficient compared to semiconductor nanoparticles containing Cd. For this reason, it has been difficult to use them as wavelength conversion materials that require a high absorption rate for blue light, such as in color filter applications.

[0010] In order to increase the absorption rate of blue light in such a wavelength conversion layer, there is an improvement method of introducing scattering particles such as inorganic oxides with a high refractive index into the wavelength conversion layer to increase the optical path length of the wavelength conversion layer. However, when introducing particles with a micrometer size that contribute significantly to scattering into the wavelength conversion layer, problems such as changes in the thickness of the wavelength conversion layer or problems with color uniformity occur when adjusting the thickness or concentration of the wavelength conversion layer. Therefore, it is difficult to improve the absorption rate of the excitation light and the light extraction efficiency after wavelength conversion in the wavelength conversion layer only by using the method of scattering particles.

[0011] The present invention has been made to solve the above problems, and an object thereof is to provide a wavelength converter with improved absorption rate for blue light and light extraction efficiency after wavelength conversion, and a wavelength conversion material in which the wavelength converter is dispersed in a resin.

Means for Solving the Problems

[0012] The present invention has been made to achieve the above object, and is a wavelength converter including, as semiconductor nanoparticles, a first semiconductor nanoparticle that converts light with a wavelength of 450 nm into light with a wavelength of λ1 nm, and a second semiconductor nanoparticle that converts light with a wavelength of 450 nm into light with a wavelength of λ2 nm, where the wavelengths λ1 and λ2 satisfy λ1 > λ2 > 450, and the wavelength converter including the first semiconductor nanoparticle and the second semiconductor nanoparticle, when irradiated with light having an excitation light quantum number N0 at a wavelength of 450 nm, the emission intensity I at wavelength λ1 1b and the emission intensity I at wavelength λ1 when the wavelength converter including only the first semiconductor nanoparticle as the semiconductor nanoparticle is irradiated with light having an excitation light quantum number N0 at the wavelength of 450 nm 1a and the relationship between them is I 1a < I 1b and provides a wavelength converter that satisfies the above.

[0013] According to such a wavelength converter, the absorption rate for blue light and the light extraction efficiency after wavelength conversion are improved.

[0014] At this time, the wavelength converter can be such that the wavelength λ1 is included in the range of 510 to 550 nm or 610 to 650 nm.

[0015] As a result, blue light can be efficiently converted into green light or red light.

[0016] At this time, the wavelength converter can be such that the wavelength λ1 is included in the range of 510 to 550 nm and the wavelength λ2 is included in the range of 480 to 510 nm. Also, the wavelength converter can be such that the wavelength λ1 is included in the range of 510 to 550 nm and the wavelength λ2 is included in the range of 490 to 500 nm.

[0017] As a result, while absorbing blue light, it becomes possible to further convert the light of wavelength λ2 into green light of wavelength λ1 on the longer wavelength side than wavelength λ2, and the light extraction efficiency of wavelength λ1 can be further improved.

[0018] At this time, the wavelength converter can be such that the wavelength λ1 is included in the range of 610 to 650 nm and the wavelength λ2 is included in the range of 480 to 600 nm. Also, the wavelength converter can be such that the wavelength λ1 is included in the range of 610 to 650 nm and the wavelength λ2 is included in the range of 490 to 500 nm or 590 to 600 nm.

[0019] As a result, while absorbing blue light, it becomes possible to further convert the light of wavelength λ2 into red light of wavelength λ1 on the longer wavelength side than wavelength λ2, and the light extraction efficiency of wavelength λ1 is further improved.

[0020] At this time, the first semiconductor nanoparticles can be a wavelength converter that is a semiconductor nanoparticle composed of a core semiconductor containing In and P and a single or a plurality of shell semiconductors covering the core semiconductor.

[0021] As a result, the first semiconductor nanoparticles and the wavelength converter have a structure that does not contain toxic substances such as Cd and Pb.

[0022] At this time, the shell semiconductor of the first semiconductor nanoparticles can be a wavelength converter composed of any one or a plurality of mixed crystal semiconductors selected from ZnS, ZnSe, ZnTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, and InSb.

[0023] As a result, the luminous efficiency and stability are further improved.

[0024] At this time, the second semiconductor nanoparticles can be a wavelength converter composed of a core semiconductor containing Zn, Se, and Te and a single or a plurality of shell semiconductors covering the core semiconductor. Further, the second semiconductor nanoparticles can be a wavelength converter composed of a core semiconductor containing Zn and P and a single or a plurality of shell semiconductors covering the core semiconductor.

[0025] As a result, the absorption rate for blue light is further improved.

[0026] At this time, the second semiconductor nanoparticles can be a wavelength converter composed of a core semiconductor that is a compound having a chalcopyrite structure and a single or a plurality of shell semiconductors covering the core semiconductor. Further, the second semiconductor nanoparticles can be a wavelength converter composed of a core semiconductor composed of any one or a plurality of mixed crystal semiconductors selected from AgGaS2, AgInS2, AgGaSe2, AgInSe2, CuGaS2, CuGaSe2, CuInS2, CuInS2, ZnSiP2, and ZnGeP2 and a single or a plurality of shell semiconductors covering the core semiconductor.

[0027] As a result, the absorption rate for blue light is further improved.

[0028] At this time, the wavelength converter can be such that the shell semiconductor of the second semiconductor nanoparticle is composed of a II-VI group compound semiconductor. Further, the wavelength converter can be such that the shell semiconductor of the second semiconductor nanoparticle is composed of a semiconductor of a mixed crystal of any one or more of ZnSe and ZnS.

[0029] Such a thing is particularly preferable from the viewpoints of improving luminous efficiency and stability.

[0030] At this time, the wavelength converter can be such that the absorbance of a dispersion liquid in which 1.0 mg of the first semiconductor nanoparticles is dispersed in 1.0 mL of a solvent at an optical path length of 1 cm with respect to light having a wavelength of 450 nm is 0.7 or more.

[0031] As a result, the absorption rate of blue light is improved, and the light extraction efficiency of light having a wavelength of λ1 is improved.

[0032] At this time, the wavelength converter can be such that the absorbance of a dispersion liquid in which 1.0 mg of the second semiconductor nanoparticles is dispersed in 1.0 mL of a solvent at an optical path length of 1 cm with respect to light having a wavelength of 450 nm is 1.0 or more, preferably 1.2 or more, more preferably 1.4 or more.

[0033] As a result, the absorption rate of blue light is improved, the light extraction efficiency of light having a wavelength of λ2 is improved, and the light having a wavelength of λ2 is further converted into a wavelength of λ1, so that the light extraction efficiency of light having a wavelength of λ1 is further improved.

[0034] At this time, the wavelength converter can be such that the internal quantum efficiency of the first semiconductor nanoparticles is 70% or more. Further, the wavelength converter can be such that the internal quantum efficiency of the second semiconductor nanoparticles is 40% or more.

[0035] As a result, the light extraction efficiency is further improved.

[0036] At this time, the wavelength converter can be such that the value of the mass ratio of the second semiconductor nanoparticles to the first semiconductor nanoparticles is 0.3 or less.

[0037] If it is within such a range of mass ratio, light leakage of the light with wavelength λ2, which is the light emission of the second semiconductor nanoparticles from the wavelength converter, can be more effectively prevented, and only the light with wavelength λ1 can be stably extracted to the outside.

[0038] At this time, the wavelength converter can be a wavelength conversion material in which the above wavelength converter is dispersed in a resin.

[0039] With such a wavelength conversion material, the absorption rate for blue light and the light extraction efficiency after wavelength conversion are improved.

Advantages of the Invention

[0040] As described above, according to the wavelength converter of the present invention, the absorption rate for blue light and the light extraction efficiency after wavelength conversion are improved.

Brief Description of the Drawings

[0041]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0042] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

[0043] As described above, there has been a demand for a wavelength converter with an improved absorption rate for blue light and a light extraction efficiency after wavelength conversion.

[0044] As a result of intensive studies on the above problems, the present inventors have found a wavelength converter comprising, as semiconductor nanoparticles, a first semiconductor nanoparticle that converts light with a wavelength of 450 nm into light with a wavelength of λ1 nm, and a second semiconductor nanoparticle that converts light with a wavelength of 450 nm into light with a wavelength of λ2 nm, where λ1 and λ2 satisfy λ1 > λ2 > 450. When the wavelength converter containing the first semiconductor nanoparticle and the second semiconductor nanoparticle is irradiated with light having an excitation photon number N0 at a wavelength of 450 nm, the emission intensity I at wavelength λ1 1b and the emission intensity I at wavelength λ1 when the wavelength converter containing only the first semiconductor nanoparticle as the semiconductor nanoparticle is irradiated with light having an excitation photon number N0 at the wavelength of 450 nm 1a satisfy the relationship I 1a < I 1b The inventors have found that a wavelength converter satisfying the above conditions improves the absorption rate for blue light and the light extraction efficiency after wavelength conversion, and thus completed the present invention.

[0045] Hereinafter, the present invention will be described with reference to the drawings. In the present invention, "converting into light with a wavelength of λ nm" means converting into light having a peak emission wavelength in the vicinity of λ nm.

[0046] [Wavelength Converter] FIG. 1 schematically shows wavelength conversion by a wavelength conversion material including wavelength conversion according to the present invention. The wavelength converter 100 according to the present invention includes a first semiconductor nanoparticle 101 and a second semiconductor nanoparticle 102 as shown in FIG. 1.

[0047] As schematically shown in FIG. 2, a part of the light 110 with a wavelength of 450 nm irradiated from the blue LED light source 103 is absorbed by the first semiconductor nanoparticle 101, and the first semiconductor nanoparticle 101 converts it into light 111x with a wavelength of λ1 converted from the light with a wavelength of 450 nm.

[0048] Similarly, as schematically shown in FIG. 3, a part of the light 110 with a wavelength of 450 nm irradiated from the blue LED light source 103 is absorbed by the second semiconductor nanoparticles 102, and the second semiconductor nanoparticles 102 convert it into light 112 with a wavelength of λ2 from the light with a wavelength of 450 nm.

[0049] When the wavelength converter 100 including such first semiconductor nanoparticles 101 and second semiconductor nanoparticles 102 is irradiated with light having a wavelength of 450 nm from a light source such as a blue LED light source 103, as shown in FIG. 1, a part of the light 110 with a wavelength of 450 nm irradiated from the blue LED light source (the light 110x with a wavelength of 450 nm absorbed by the first semiconductor nanoparticles) is absorbed by the first semiconductor nanoparticles 101, and a part (the light 110y with a wavelength of 450 nm absorbed by the second semiconductor nanoparticles) is absorbed by the second semiconductor nanoparticles 102. Similar to FIG. 2, the light 110x with a wavelength of 450 nm absorbed by the first semiconductor nanoparticles becomes light 111x with a wavelength of λ1 converted from the light with a wavelength of 450 nm by the first semiconductor nanoparticles 101.

[0050] Also, similar to FIG. 3, the light 110y with a wavelength of 450 nm absorbed by the second semiconductor nanoparticles becomes light 112 with a wavelength of λ2 converted from the light with a wavelength of 450 nm by the second semiconductor nanoparticles 102. At this time, when λ1 and λ2 satisfy the relationship of λ1>λ2>450 nm, the light 112 with a wavelength of λ2 converted from the light with a wavelength of 450 nm is further absorbed by the first semiconductor nanoparticles 101, and the first semiconductor nanoparticles 101 convert it into light 111y with a wavelength of λ1 from the light with a wavelength of λ2.

[0051] As a result, the light 111z with a wavelength of λ1 taken out of the wavelength converter to the outside is the sum of the light 111x with a wavelength of λ1 converted from the light with a wavelength of 450 nm and the light 111y with a wavelength of λ1 converted from the light with a wavelength of λ2. That is, the emission intensity I at the wavelength λ1 when the wavelength converter 100 including the first semiconductor nanoparticles 101 and the second semiconductor nanoparticles 102 is irradiated with light having an excitation photon number N0 at a wavelength of 450 nm 1bAnd, for the wavelength converter containing only the first semiconductor nanoparticles 101 as semiconductor nanoparticles, when irradiated with light having an excitation photon number N0 at a wavelength of 450 nm, the emission intensity I at the wavelength λ1 1a and the relationship is such that I 1a <I 1b satisfies the condition. That is, the absorption rate for blue light is improved, and the extraction efficiency of the light with the wavelength λ1 extracted from the wavelength converter is improved.

[0052] Thus, the present inventors have found that by using the wavelength converter 100 containing the first semiconductor nanoparticles 101 and the second semiconductor nanoparticles 102 as described above, the absorption rate for blue light and the light extraction efficiency can be improved.

[0053] The light with the wavelength λ1 is preferably green light or red light, and the value of the wavelength λ1 is preferably in the range of 510 to 550 nm or 610 to 650 nm. By using the first semiconductor nanoparticles with such a value of the wavelength λ1, the above wavelength converter becomes a wavelength converter that efficiently converts blue light into green light or red light.

[0054] Further, when the wavelength λ1 is in the range of 510 to 550 nm, the value of the wavelength λ2 is preferably in the range of 480 to 510 nm, more preferably 490 to 500 nm. If the wavelength λ2 is in such a value range, it can absorb blue light and further convert the light with the wavelength λ2 into green light with the wavelength λ1 on the longer wavelength side than the wavelength λ2, resulting in a wavelength converter with further improved light extraction efficiency of the light with the wavelength λ1.

[0055] Further, when the wavelength λ1 is in the range of 610 to 650 nm, the value of the wavelength λ2 is preferably in the range of 480 to 600 nm, more preferably 490 to 500 nm or 590 to 600 nm. If the wavelength λ2 is in such a value range, it can absorb blue light and further convert the light with the wavelength λ2 into red light with the wavelength λ1 on the longer wavelength side than the wavelength λ2, resulting in a wavelength converter with further improved light extraction efficiency of the light with the wavelength λ1.

[0056] The structures of the first and second semiconductor nanoparticles according to the present invention are not particularly limited, but from the viewpoints of fluorescence emission characteristics and stability, semiconductor nanoparticles having a core-shell structure are preferable. That is, it is preferable to include a core semiconductor that is a nanoparticle and a single or a plurality of shell semiconductors that cover the core semiconductor. In a core / shell structure semiconductor nanoparticle having a nano-sized semiconductor particle as a core and a semiconductor having a larger band gap and lower lattice mismatch than the core as a shell, excitons generated in the shell are confined inside the core particles, so that the fluorescence emission efficiency is improved, and further, since the core surface is covered with the shell, the stability is improved.

[0057] The composition of the first semiconductor nanoparticles is not particularly limited, and examples thereof include materials having In and P as cores. By adopting such a composition, the first semiconductor nanoparticles and the wavelength converter are made of materials that do not contain toxic substances such as Cd and Pb.

[0058] The shell material of the first semiconductor nanoparticles is not particularly limited, but those having a larger band gap and lower lattice mismatch with respect to the core material are preferable, and a semiconductor composed of an alloy or a plurality of mixed crystals of II-VI group compounds or III-V group compounds is selected. Specific shell materials may also be selected as any one or a plurality of mixed crystal semiconductors selected from ZnS, ZnSe, ZnTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, and InSb. Among these materials, ZnSe and ZnS are particularly preferable from the viewpoints of improving the emission efficiency and stability.

[0059] The composition of the second semiconductor nanoparticles is not particularly limited, but a material that strongly absorbs blue light is desirable. For example, materials containing Zn, Te, and Se as cores, materials containing Zn and P as cores, and materials having a chalcopyrite structure ternary compound such as AgGaS2, AgInS2, AgGaSe2, AgInSe2, CuGaS2, CuGaSe2, CuInS2, CuInS2, ZnSiP2, ZnGeP2 as cores can be mentioned. Materials having such a composition are known to have a high absorption coefficient for blue light. If the second semiconductor nanoparticles have such a composition, the absorption rate of the wavelength converter for blue light is improved.

[0060] The shell material of the second semiconductor nanoparticles is not particularly limited, but a II-VI group compound is preferable. Among these materials, those composed of a semiconductor shell composed of one or more mixed crystals of ZnSe, ZnS, or a combination thereof are particularly preferable from the viewpoints of improving luminous efficiency and stability.

[0061] There are various methods for producing semiconductor nanoparticles, such as a liquid phase method and a gas phase method, but they are not particularly limited in the semiconductor nanoparticles according to the present invention. From the viewpoint of exhibiting high fluorescence emission efficiency, it is preferable to use semiconductor nanoparticles obtained by using a hot soap method or a hot injection method in which precursor species are reacted at a high temperature in a high-boiling nonpolar solvent.

[0062] In addition, in order to reduce surface defects, it is preferable that organic ligands called ligands are coordinated on the surface of the semiconductor nanoparticles. From the viewpoint of suppressing aggregation of the semiconductor nanoparticles, the ligand preferably contains an aliphatic hydrocarbon. Examples of such ligands include oleic acid, stearic acid, palmitic acid, myristic acid, lauric acid, decanoic acid, octanoic acid, oleylamine, stearyl (octadecyl) amine, dodecyl (lauryl) amine, decylamine, octylamine, octadecanethiol, hexadecanethiol, tetradecanethiol, dodecanethiol, decanethiol, octanethiol, trioctylphosphine, trioctylphosphine oxide, triphenylphosphine, triphenylphosphine oxide, tributylphosphine, tributylphosphine oxide, etc. These may be used alone or in combination of a plurality.

[0063] The first semiconductor nanoparticles preferably have an internal quantum efficiency of 70% or more. Also, the second semiconductor nanoparticles preferably have an internal quantum efficiency of 40% or more. The light extraction efficiency of the light with wavelength λ1 is further improved.

[0064] Also, the higher the absorbance of the first semiconductor nanoparticles with respect to blue light, the more preferable. For example, when the first semiconductor nanoparticles are dispersed in 1.0 ml of a solvent, the absorbance with respect to blue light with a wavelength of 450 nm at an optical path length of 1 cm is preferably 0.7 or more. The solvent is not particularly limited, but examples include nonpolar solvents such as toluene and hexane. With such semiconductor nanoparticles, the absorption rate of blue light is further improved, and the light extraction efficiency of the light with wavelength λ1 is further improved.

[0065] Also, the higher the absorbance of the second semiconductor nanoparticles for blue light, the more desirable. For example, when the second semiconductor nanoparticles are dispersed in 1.0 ml of a solvent, the absorbance for blue light with a wavelength of 450 nm at an optical path length of 1 cm is preferably 1.0 or more, more preferably 1.2 or more, and even more preferably 1.4 or more. The solvent is not particularly limited, but examples include nonpolar solvents such as toluene and hexane. With such semiconductor nanoparticles, the absorption rate of blue light is further improved, the light extraction efficiency of wavelength λ2 is further improved, and when used as a wavelength converter, the light of wavelength λ2 is further converted to wavelength λ1, thereby further improving the light extraction efficiency of wavelength λ1.

[0066] The higher the absorbance of the wavelength converter when irradiated with blue excitation light, the more desirable. In particular, when the wavelength converter is applied to uses such as color filters, the absorbance for excitation light is preferably 90% or more, and more preferably 95% or more.

[0067] If the absorption of light with wavelength λ2 by the first semiconductor nanoparticles in the wavelength converter is insufficient, the light with wavelength λ2 may leak to the outside. When the light with wavelength λ2 leaks, color mixing occurs and the color purity of the emission spectrum decreases. To prevent the leakage of light with wavelength λ2 from the wavelength converter, the value of the mass ratio of the second semiconductor nanoparticles to the first semiconductor nanoparticles is preferably 0.3 or less. Within such a mass ratio range, the leakage of light with wavelength λ2, which is the emission of the second semiconductor nanoparticles from the wavelength converter, can be effectively prevented, and only the light with wavelength λ1 can be stably extracted to the outside.

[0068] The wavelength converter may contain semiconductor nanoparticles other than the above-described first semiconductor nanoparticles and second semiconductor nanoparticles.

[0069] [Wavelength Conversion Material] The wavelength converter can also be used as a wavelength conversion material dispersed in a resin. The resin material is not particularly limited, but preferably one in which the wavelength converter does not aggregate or the fluorescence emission efficiency does not deteriorate. Examples include silicone resin, acrylic resin, epoxy resin, urethane resin, fluororesin, etc. These materials preferably have a high transmittance in order to enhance the fluorescence emission efficiency as a wavelength conversion material, and particularly preferably have a transmittance of 80% or more. With such a wavelength conversion material, the absorption rate for blue light and the light extraction efficiency after wavelength conversion are improved.

[0070] In the wavelength conversion material according to the present invention, the proportion of the wavelength converter is preferably 15% by mass to 65% by mass. By being in such a range, a wavelength conversion material with a more stable and higher absorption rate for blue light is provided. Also, when the proportion of the wavelength converter in the wavelength conversion material is 70% by mass or less, insufficient curing due to a decrease in the proportion of the resin component can be stably prevented. From these viewpoints, the proportion of the wavelength converter in the wavelength conversion material is more preferably 20 to 60% by mass.

[0071] The wavelength conversion material may further contain scattering particles. By incorporating scattering particles with a high refractive index into the wavelength conversion material, the excitation light is scattered, the substantial optical path length in the wavelength conversion layer can be lengthened, and the light extraction efficiency is further improved. The type of the scattering particles is not particularly limited, and examples include inorganic oxides. Specifically, Al2O3, ZrO2, TiO2, SiO2, MgO, ZnO, BaTiO3, SnO are mentioned, and the scattering particles may be used alone or in combination of two or more selected from these. The size of the scattering particles preferably has an average particle diameter of 50 to 1000 nm, and more preferably 100 to 500 nm. Although it also depends on the particle diameter of the scattering particles, from the viewpoint of preventing turbidity of the wavelength conversion material, 1 to 30% by mass is preferable with respect to the wavelength conversion material, and 3 to 20% by mass is more preferable.

Examples

[0072] Hereinafter, the present invention will be specifically described with reference to examples, but this does not limit the present invention.

[0073] [Manufacture and Evaluation of Semiconductor Nanoparticles] (Measurement) As the evaluation of the fluorescence emission characteristics of the semiconductor nanoparticles in the production example, the emission wavelength peak and the internal quantum efficiency at an excitation wavelength of 450 nm were measured using a quantum efficiency measurement system (QE-2100, manufactured by Otsuka Electronics Co., Ltd.).

[0074] The absorbance of the semiconductor nanoparticles was evaluated using an ultraviolet-visible-near-infrared spectrophotometer (V-750, manufactured by JASCO Corporation). 1.0 mg of the semiconductor nanoparticles was dispersed in 1.0 mL of toluene solvent, placed in a cell with a width of 1 cm, and the absorbance was evaluated.

[0075] (Production Example 1) 0.070 g (0.24 mmol) of indium acetate, 0.256 g (0.72 mmol) of palmitic acid, and 4.0 mL of 1-octadecene were added into a flask. Under reduced pressure, heating and stirring were carried out at 100 °C for 1 hour for degassing while dissolving. After the flask was cooled to room temperature, nitrogen was purged, and 0.50 mL (0.17 mmol) of 10 vol% (tris) trimethylsilylphosphine / octadecene solution was added to the flask. The flask was heated to 300 °C and stirred for 20 minutes to synthesize core semiconductor nanoparticles. Then, after the flask was cooled to 200 °C, 4.0 mL (1.2 mmol) of 0.30 M zinc stearate / octadecene solution was added and stirred for 30 minutes. Further, 0.60 mL (0.90 mmol) of 1.5 M selenium / trioctylphosphine solution was added to the flask and stirred for 30 minutes. Next, after the flask was cooled to room temperature, 0.22 g (1.2 mmol) of zinc acetate was added, and heating and stirring were carried out at 100 °C under reduced pressure for 1 hour for degassing while dissolving. After purging nitrogen into the flask, it was heated to 230 °C, 0.48 mL (2.0 mmol) of 1-DDT (dodecanethiol) was added, and stirred for 30 minutes. The obtained solution was cooled to room temperature, ethanol was added, and centrifuged to precipitate semiconductor nanoparticles and remove the supernatant. Further, toluene was added to the precipitate for dispersion, ethanol was added again for centrifugation, the supernatant was removed and redispersed in toluene to prepare an InP / ZnSe / ZnS semiconductor nanoparticle toluene solution. The fluorescence emission wavelength peak of the solution was 534 nm, the internal quantum efficiency of the solution was 76%, and the absorbance at 450 nm of light was 0.8.

[0076] (Production Example 2) 0.175 g (0.6 mmol) of indium acetate, 0.640 g (1.8 mmol) of palmitic acid, and 10.0 mL of 1-octadecene were added into a flask. Under reduced pressure, the mixture was heated with stirring at 100 °C and degassed for 1 hour while dissolving. After the flask was cooled to room temperature, nitrogen was purged, and 1.0 mL (0.34 mmol) of 10 vol% (tris) trimethylsilylphosphine / octadecene solution was added to the flask. The flask was heated to 300 °C and stirred for 30 minutes to synthesize core semiconductor nanoparticles. Next, after the flask was cooled to 200 °C, 6.0 mL (1.8 mmol) of 0.30 M zinc stearate / octadecene solution was added and stirred for 30 minutes. Further, 0.90 mL (1.35 mmol) of 1.5 M selenium / trioctylphosphine solution was added to the flask and stirred for 30 minutes. Next, after the flask was cooled to room temperature, 0.44 g (2.4 mmol) of zinc acetate was added, and under reduced pressure, the mixture was heated with stirring at 100 °C and degassed for 1 hour while dissolving. After purging nitrogen into the flask, it was heated to 230 °C, 0.96 mL (4.0 mmol) of 1-DDT (dodecanethiol) was added, and stirred for 30 minutes. The obtained solution was cooled to room temperature, ethanol was added, and the semiconductor nanoparticles were precipitated by centrifugation to remove the supernatant. Further, toluene was added to the precipitate for dispersion, ethanol was added again for centrifugation, the supernatant was removed and redispersed in toluene to prepare an InP / ZnSe / ZnS semiconductor nanoparticle toluene solution. The fluorescence emission wavelength peak of the solution was 622 nm, the internal quantum efficiency was 72%, and the absorbance at 450 nm light was 0.7.

[0077] (Production Example 3) 0.066 g (0.36 mmol) of zinc acetate, 0.24 mL (0.76 mmol) of oleic acid, 4.0 mL of ODE, and 0.15 mL of oleylamine were added into a flask. Under reduced pressure, heating and stirring were carried out at 100 °C for 1 hour for degassing. Then, nitrogen was purged into the flask and heated to 260 °C. When the temperature of the solution was stabilized, 0.70 mL (0.24 mmol) of 10 vol% (tris) trimethylsilylphosphine / octadecene solution was added to the flask. The flask was heated to 300 °C and stirred, and held for 20 minutes to synthesize core semiconductor nanoparticles. 3.0 g (4.74 mmol) of zinc stearate and 15 mL of octadecene were added into another flask, heated and dissolved at 100 °C, and stirred under vacuum for 1 hour for degassing to prepare a zinc precursor solution. 3.0 mL (0.95 mmol) of zinc stearate solution was added into the flask of core semiconductor nanoparticles held at 270 °C and held for 30 minutes. Then, 0.16 g (5.0 mmol) of sulfur and 4.0 mL of trioctylphosphine were added, heated and dissolved at 150 °C, a 1.25 M sulfur / trioctylphosphine solution was prepared, 1.0 mL was added to the reaction solution, and stirred for 1 hour. Subsequently, 0.22 g (1.1 mmol) of zinc acetate was added and dissolved by heating and stirring at 100 °C under reduced pressure. Nitrogen was purged into the flask again, the temperature was raised to 230 °C, 0.48 mL (2 mmol) of 1-dodecanethiol was added and held for 1 hour. The obtained solution was cooled to room temperature, ethanol was added, and centrifuged to precipitate semiconductor nanoparticles and remove the supernatant. Further, toluene was added for dispersion, ethanol was added again and centrifuged, the supernatant was removed and redispersed in toluene to prepare a Zn3P2 / ZnS solution. The fluorescence emission wavelength peak of the solution was 493 nm, the internal quantum efficiency was 42%, and the absorbance at 450 nm light was 1.2.

[0078] (Production Example 4) 2.0 mL of oleic acid and 10 mL of 1-octadecene were added into a flask, and the mixture was heated and stirred at 100 °C under reduced pressure for 1 hour for degassing. Then, nitrogen was purged into the flask and the mixture was heated to 270 °C. When the temperature of the solution was stabilized, Te was added to trioctylphosphine and dissolved, and 0.2 mL of a tellurium / trioctylphosphine solution adjusted to 0.3 M, and Se (selenium) was added to trioctylphosphine and dissolved, and 0.8 mL of a selenium / trioctylphosphine solution adjusted to 0.3 M were added into the flask. Further, 0.3 mmol of a diethylzinc solution was added, and the mixture was held at 270 °C for 30 minutes to synthesize core semiconductor nanoparticles. 3.0 g (4.74 mmol) of zinc stearate and 15 mL of octadecene were added into another flask, heated and dissolved at 100 °C, and stirred for 1 hour under evacuation for degassing to prepare a zinc precursor solution. 10 mL (3.16 mmol) of the zinc stearate solution and 2.4 mL (0.3 mmol) of a 1.25 M selenium / trioctylphosphine solution adjusted in another flask were simultaneously added to the reaction solution at 270 °C and stirred for 30 minutes. Then, 4.0 mL of trioctylphosphine was added to 0.16 g (5.0 mmol) of sulfur and heated to 150 °C for dissolution to prepare a 1.25 M sulfur / trioctylphosphine solution, and 1.0 mL of the solution was added to the reaction solution and stirred for 1 hour. Subsequently, 0.22 g (1.1 mmol) of zinc acetate was added and dissolved by heating and stirring at 100 °C under reduced pressure. The inside of the flask was purged with nitrogen again and heated to 230 °C, and 0.48 mL (2 mmol) of 1-dodecanethiol was added and held for 1 hour. The obtained solution was cooled to room temperature, ethanol was added, and centrifuged to precipitate semiconductor nanoparticles and remove the supernatant. Further, toluene was added for dispersion, ethanol was added again and centrifuged, the supernatant was removed and redispersed in toluene to prepare a ZnTeSe / ZnSe / ZnS solution. The fluorescence emission wavelength peak of the solution was 498 nm, the internal quantum efficiency was 45%, and the absorbance at 450 nm of light was 1.4.

[0079] (Production Example 5) 0.033 g (0.20 mmol) of silver(I) acetate, 0.058 g (0.20 mmol) of indium acetate, 0.65 mL (2.7 mmol) of 1-dodecanethiol, and 4.0 mL of oleylamine were added into a flask. Under reduced pressure, heating and stirring were carried out at 100 °C for 1 hour for degassing. Then, nitrogen was purged into the flask, heated to 200 °C, and held for 20 minutes. Subsequently, after heating the flask to 230 °C, 1.25 M sulfur / trioctylphosphine solution was prepared and 1.0 mL was added to the reaction solution, followed by stirring for 1 hour. Finally, 0.066 g (0.36 mmol) of zinc acetate, 0.24 mL (0.76 mmol) of oleic acid, and 0.15 mL of oleylamine were added to the flask, and heating and stirring were carried out at 230 °C for 1 hour. The obtained solution was cooled to room temperature, ethanol was added, and centrifuged to precipitate the semiconductor nanoparticles and remove the supernatant. Further, toluene was added for dispersion, ethanol was added again and centrifuged, the supernatant was removed, and redispersed in toluene to prepare an AgInS2 / ZnS solution. The fluorescence emission wavelength peak of the solution was 597 nm, the internal quantum efficiency was 56%, and the absorbance at 450 nm light was 1.0.

[0080] [Manufacture and Evaluation of Wavelength Converter] In order to manufacture a wavelength converter composed of the first semiconductor nanoparticles and the second semiconductor nanoparticles, the first semiconductor nanoparticles were selected from the semiconductor nanoparticles of Production Example 1 or Production Example 2, and the second semiconductor nanoparticles were selected from the semiconductor nanoparticles of Production Example 3 or Production Example 4 or Production Example 5, and the wavelength converter was prepared by adjusting these semiconductor nanoparticles to an arbitrary mass ratio with respect to 1.0 mL of toluene solvent.

[0081] (Measurement) For the evaluation of the fluorescence emission characteristics of the semiconductor nanoparticles in the wavelength converters of the Examples and Comparative Examples, the absorption rate of the excitation light, the emission wavelength peak, and the emission intensity of the emission wavelength peak at an excitation wavelength of 450 nm were measured using a quantum efficiency measurement system (QE-2100: manufactured by Otsuka Electronics Co., Ltd.).

[0082] (Example 1) 1.0 mg of the semiconductor nanoparticles synthesized in Production Example 1 and 0.10 mg of the semiconductor nanoparticles synthesized in Production Example 3 were dispersed in 1.0 mL of a toluene solution to prepare a dispersion of the wavelength converter. When the wavelength converter was irradiated with light having an excitation photon number N0 = 4.7×10 11 photons at a blue light of 450 nm, the absorption rate of the blue light was 52.1%, and the emission intensity I 1b of the light with a wavelength λ1 = 534 nm was 1.21×10 -3 .

[0083] (Example 2) 1.0 mg of the semiconductor nanoparticles synthesized in Production Example 1 and 0.20 mg of the semiconductor nanoparticles synthesized in Production Example 3 were dispersed in 1.0 mL of a toluene solution to prepare a dispersion of the wavelength converter. When the wavelength converter was irradiated with light having an excitation photon number N0 = 4.7×10 11 photons at a blue light of 450 nm, the absorption rate of the blue light was 59.5%, and the emission intensity I 1b of the light with a wavelength λ1 = 534 nm was 1.38×10 -3 .

[0084] (Example 3) 1.0 mg of the semiconductor nanoparticles synthesized in Production Example 1 and 0.30 mg of the semiconductor nanoparticles synthesized in Production Example 3 were dispersed in 1.0 mL of a toluene solution to prepare a dispersion of the wavelength converter. When the wavelength converter was irradiated with light having an excitation photon number N0 = 4.7×10 11 photons at a blue light of 450 nm, the absorption rate of the blue light was 66.1%, and the emission intensity I 1b of the light with a wavelength λ1 = 534 nm was 1.52×10 -3 .

[0085] (Example 4) 1.1 mg of the semiconductor nanoparticles synthesized in Production Example 1 and 0.33 mg of the semiconductor nanoparticles synthesized in Production Example 3 were dispersed in 1.0 mL of a toluene solution to prepare a dispersion of the wavelength converter. When the wavelength converter was irradiated with light having an excitation photon number N0 = 4.7×10 11 photons at a blue light of 450 nm, the absorption rate of the blue light was 74.2%, and the emission intensity I 1b of the light with a wavelength λ1 = 534 nm was 1.69×10 -3It was.

[0086] (Example 5) A dispersion of a wavelength converter was prepared by dispersing 1.2 mg of the semiconductor nanoparticles synthesized in Production Example 1 and 0.36 mg of the semiconductor nanoparticles synthesized in Production Example 3 in 1.0 mL of a toluene solution. When the wavelength converter was irradiated with light having an excitation photon number N0 = 4.7×10 11 photons at a blue light of 450 nm, the absorption rate of the blue light was 81.6%, and the emission intensity I 1b of the light with a wavelength λ1 = 534 nm was 1.84×10 -3 It was.

[0087] (Example 6) A dispersion of a wavelength converter was prepared by dispersing 1.3 mg of the semiconductor nanoparticles synthesized in Production Example 1 and 0.39 mg of the semiconductor nanoparticles synthesized in Production Example 3 in 1.0 mL of a toluene solution. When the wavelength converter was irradiated with light having an excitation photon number N0 = 4.7×10 11 photons at a blue light of 450 nm, the absorption rate of the blue light was 87.0%, and the emission intensity I 1b of the light with a wavelength λ1 = 534 nm was 2.01×10 -3 It was.

[0088] (Example 7) A dispersion of a wavelength converter was prepared by dispersing 1.4 mg of the semiconductor nanoparticles synthesized in Production Example 1 and 0.42 mg of the semiconductor nanoparticles synthesized in Production Example 3 in 1.0 mL of a toluene solution. When the wavelength converter was irradiated with light having an excitation photon number N0 = 4.7×10 11 photons at a blue light of 450 nm, the absorption rate of the blue light was 92.6%, and the emission intensity I 1b of the light with a wavelength λ1 = 534 nm was 2.11×10 -3 It was.

[0089] (Example 8) A dispersion of a wavelength converter was prepared by dispersing 1.6 mg of the semiconductor nanoparticles synthesized in Production Example 1 and 0.48 mg of the semiconductor nanoparticles synthesized in Production Example 3 in 1.0 mL of a toluene solution. When the wavelength converter was irradiated with light having an excitation photon number N0 = 4.7×10 11When irradiated with a single light, the absorption rate of blue light was 95.1%, and the emission intensity I of the light with a wavelength λ1 = 534 nm 1b was 2.20×10 -3 .

[0090] (Example 9) A dispersion of a wavelength converter was prepared by dispersing 1.0 mg of the semiconductor nanoparticles synthesized in Production Example 2 and 0.30 mg of the semiconductor nanoparticles synthesized in Production Example 3 in 1.0 mL of a toluene solution. When the wavelength converter was irradiated with N0 = 4.7×10 11 photons of blue light at 450 nm, the absorption rate of blue light was 64.2%, and the emission intensity I of the light with a wavelength λ1 = 622 nm 1b was 1.39×10 -3 .

[0091] (Example 10) A dispersion of a wavelength converter was prepared by dispersing 1.4 mg of the semiconductor nanoparticles synthesized in Production Example 2 and 0.42 mg of the semiconductor nanoparticles synthesized in Production Example 3 in 1.0 mL of a toluene solution. When the wavelength converter was irradiated with N0 = 4.7×10 11 photons of blue light at 450 nm, the absorption rate of blue light was 85.7%, and the emission intensity I of the light with a wavelength λ1 = 622 nm 1b was 1.82×10 -3 .

[0092] (Example 11) A dispersion of a wavelength converter was prepared by dispersing 1.6 mg of the semiconductor nanoparticles synthesized in Production Example 2 and 0.48 mg of the semiconductor nanoparticles synthesized in Production Example 3 in 1.0 mL of a toluene solution. When the wavelength converter was irradiated with N0 = 4.7×10 11 photons of blue light at 450 nm, the absorption rate of blue light was 90.4%, and the emission intensity I of the light with a wavelength λ1 = 622 nm 1b was 1.96×10 -3 .

[0093] (Example 12) 1.3 mg of the semiconductor nanoparticles synthesized in Production Example 1 and 0.39 mg of the semiconductor nanoparticles synthesized in Production Example 4 were dispersed in 1.0 mL of a toluene solution to prepare a dispersion of the wavelength converter. When the wavelength converter was irradiated with light having an excitation photon number N0 = 4.7×10 11 photons at a blue light of 450 nm, the absorption rate of the blue light was 90.7%, and the emission intensity I 1b of the light with a wavelength λ1 = 534 nm was 2.09×10 -3 .

[0094] (Example 13) 1.4 mg of the semiconductor nanoparticles synthesized in Production Example 1 and 0.42 mg of the semiconductor nanoparticles synthesized in Production Example 4 were dispersed in 1.0 mL of a toluene solution to prepare a dispersion of the wavelength converter. When the wavelength converter was irradiated with light having an excitation photon number N0 = 4.7×10 11 photons at a blue light of 450 nm, the absorption rate of the blue light was 93.5%, and the emission intensity I 1b of the light with a wavelength λ1 = 534 nm was 2.13×10 -3 .

[0095] (Example 14) 1.4 mg of the semiconductor nanoparticles synthesized in Production Example 2 and 0.42 mg of the semiconductor nanoparticles synthesized in Production Example 4 were dispersed in 1.0 mL of a toluene solution to prepare a dispersion of the wavelength converter. When the wavelength converter was irradiated with light having an excitation photon number N0 = 4.7×10 11 photons at a blue light of 450 nm, the absorption rate of the blue light was 87.0%, and the emission intensity I 1b of the light with a wavelength λ1 = 622 nm was 1.87×10 -3 .

[0096] (Example 15) 1.6 mg of the semiconductor nanoparticles synthesized in Production Example 2 and 0.48 mg of the semiconductor nanoparticles synthesized in Production Example 4 were dispersed in 1.0 mL of a toluene solution to prepare a dispersion of the wavelength converter. When the wavelength converter was irradiated with light having an excitation photon number N0 = 4.7×10 11 photons at a blue light of 450 nm, the absorption rate of the blue light was 91.0%, and the emission intensity I 1b of the light with a wavelength λ1 = 622 nm was 1.98×10 -3It was.

[0097] (Example 16) A dispersion of a wavelength converter was prepared by dispersing 1.4 mg of semiconductor nanoparticles synthesized in Production Example 2 and 0.42 mg of semiconductor nanoparticles synthesized in Production Example 5 in 1.0 mL of a toluene solution. When the wavelength converter was irradiated with light having an excitation photon number N0 = 4.7×10 11 photons at a blue light of 450 nm, the absorption rate of the blue light was 79.8%, and the emission intensity I 1b of light with a wavelength λ1 = 622 nm was 1.80×10 -3 It was.

[0098] (Example 17) A dispersion of a wavelength converter was prepared by dispersing 1.8 mg of semiconductor nanoparticles synthesized in Production Example 2 and 0.54 mg of semiconductor nanoparticles synthesized in Production Example 5 in 1.0 mL of a toluene solution. When the wavelength converter was irradiated with light having an excitation photon number N0 = 4.7×10 11 photons at a blue light of 450 nm, the absorption rate of the blue light was 90.2%, and the emission intensity I 1b of light with a wavelength λ1 = 622 nm was 1.95×10 -3 It was.

[0099] (Comparative Example 1) A dispersion of a wavelength converter was prepared by dispersing 1.0 mg of semiconductor nanoparticles synthesized in Production Example 1 in 1.0 mL of a toluene solution. When the wavelength converter was irradiated with light having an excitation photon number N0 = 4.7×10 11 photons at a blue light of 450 nm, the absorption rate of the blue light was 43.6%, and the emission intensity I 1a of light with a wavelength λ1 = 534 nm was 1.05×10 -3 It was.

[0100] (Comparative Example 2) A dispersion of a wavelength converter was prepared by dispersing 1.4 mg of semiconductor nanoparticles synthesized in Production Example 1 in 1.0 mL of a toluene solution. When the wavelength converter was irradiated with light having an excitation photon number N0 = 4.7×10 11 photons at a blue light of 450 nm, the absorption rate of the blue light was 60.8%, and the emission intensity I 1awas 1.41×10 -3 It was

[0101] (Comparative Example 3) A dispersion of a wavelength converter was prepared by dispersing 1.0 mg of the semiconductor nanoparticles synthesized in Production Example 2 in 1.0 mL of a toluene solution. When the wavelength converter was irradiated with light having a quantum number of excitation light N0 = 4.7×10 11 photons at a blue light of 450 nm, the absorption rate of the blue light was 41.8%, and the emission intensity I 1a of the light with a wavelength λ1 = 622 nm was 0.96×10 -3 It was

[0102] (Comparative Example 4) A dispersion of a wavelength converter was prepared by dispersing 1.4 mg of the semiconductor nanoparticles synthesized in Production Example 2 in 1.0 mL of a toluene solution. When the wavelength converter was irradiated with light having a quantum number of excitation light N0 = 4.7×10 11 photons at a blue light of 450 nm, the absorption rate of the blue light was 58.5%, and the emission intensity I 1a of the light with a wavelength λ1 = 622 nm was 1.30×10 -3 It was

[0103] The evaluation results of Examples 1 to 17 and Comparative Examples 1 to 4 are shown in Table 1 above.

[0104] [Table 1]

[0105] As shown in Table 1, when comparing the results of Examples 1 to 8 and Examples 12 and 13 with the results of Comparative Examples 1 and 2, the absorption rate for blue light and the emission intensity at a wavelength of 534 nm when irradiating light with a wavelength of 450 nm on a wavelength converter composed of Production Example 1 and Production Example 3 or Production Example 4 are higher than the absorption rate for blue light and the relative emission intensity when irradiating light with a wavelength of 450 nm on a wavelength converter composed of the semiconductor nanoparticles alone of Production Example 1. It was confirmed that the light extraction efficiency of green light was improved.

[0106] Further, from Table 1, when comparing the results of Examples 9 to 11 and Examples 14 to 17 with the results of Comparative Examples 3 and 4, the absorption rate for blue light and the emission intensity at a wavelength of 622 nm when irradiating light with a wavelength of 450 nm onto the wavelength converter composed of Production Example 2 and Production Example 3 or Production Example 4 or Production Example 5 are larger values than the absorption rate for blue light and the emission intensity when irradiating light with a wavelength of 450 nm onto the wavelength converter composed of the semiconductor nanoparticles alone of Production Example 2, and it was confirmed that the light extraction efficiency of red light is improved.

[0107] Also, for Examples 7, 8, 11 to 13, 15, and 17, the absorption rate for blue light is 90% or more, and the emission intensity is 1.95×10 -3 or more, and it was confirmed that in particular, the absorption rate for blue excitation light is improved and the light extraction efficiency is improved.

[0108] From these results, it can be seen that the wavelength converter according to the present invention has an improved absorption rate for blue excitation light and an improved light extraction efficiency.

[0109] Note that the present invention is not limited to the above-described embodiments. The above-described embodiments are examples, and any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits the same operational effects is included in the technical scope of the present invention.

Explanation of Reference Numerals

[0110] 100... wavelength converter, 101... first semiconductor nanoparticle, 102... second semiconductor nanoparticle, 103... blue LED light source, 110... light with a wavelength of 450 nm irradiated from the blue LED light source, 110x... light with a wavelength of 450 nm absorbed by the first semiconductor nanoparticle, 110y... light with a wavelength of 450 nm absorbed by the second semiconductor nanoparticle, 111x... light with a wavelength of λ1 converted from light with a wavelength of 450 nm, 111y... light with a wavelength of λ1 converted from light with a wavelength of λ2, 111z... Light of wavelength λ1 extracted from the wavelength converter to the outside 112... Light of wavelength λ2 converted from light of wavelength 450 nm

Claims

1. A wavelength converter, As semiconductor nanoparticles, a first semiconductor nanoparticle that converts light with a wavelength of 450 nm into light with a wavelength of λ １ nm and a second semiconductor nanoparticle that converts light with a wavelength of 450 nm into light with a wavelength of λ ２ nm, and the wavelength λ １ and the wavelength λ ２ are such that λ １ > λ ２ > 450 is satisfied, When the wavelength converter including the first semiconductor nanoparticle and the second semiconductor nanoparticle is irradiated with light having an excitation photon number N at a wavelength of 450 nm ０ the emission intensity I １ at a wavelength λ １ｂ and When the wavelength converter contains only the first semiconductor nanoparticles as semiconductor nanoparticles, the excitation photon number N of the excitation light at the wavelength of 450 nm ０ When the light of is irradiated, the wavelength λ １ At the emission intensity I １ａ The relationship with is I １ａ < I １ｂ Satisfies, The wavelength λ １ is included in the range of 510 to 550 nm, and the wavelength λ ２ is included in the range of 480 to 510 nm, characterized by a wavelength converter.

2. A wavelength converter, As semiconductor nanoparticles, a first semiconductor nanoparticle that converts light with a wavelength of 450 nm into light with a wavelength of λ １ nm, and a second semiconductor nanoparticle that converts light with a wavelength of 450 nm into light with a wavelength of λ ２ nm, and the wavelength λ １ and the wavelength λ ２ are such that λ １ > λ ２ > 450 is satisfied, When the wavelength converter including the first semiconductor nanoparticle and the second semiconductor nanoparticle is irradiated with light having an excitation photon number N at a wavelength of 450 nm, the emission intensity I ０ at a wavelength λ １ and １ｂ and For the wavelength converter containing only the first semiconductor nanoparticles as semiconductor nanoparticles, the excitation photon number N of the excitation light at the wavelength of 450 nm ０ When irradiated with light of １ the emission intensity I at the wavelength λ １ａ The relationship with is I １ａ < I １ｂ satisfies, The wavelength λ １ is included in the range of 610 to 650 nm, and the wavelength λ ２ is characterized by being included in 490 to 500 nm or 590 to 600 nm. A wavelength converter characterized by the above is provided.

3. The wavelength converter according to claim 1 or 2, wherein the first semiconductor nanoparticle is a semiconductor nanoparticle composed of a core semiconductor containing In and P and one or more shell semiconductors covering the core semiconductor.

4. The wavelength converter according to claim 3, wherein the shell semiconductor of the first semiconductor nanoparticle is composed of any one or more mixed crystal semiconductors selected from ZnS, ZnSe, ZnTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, and InSb.

5. The wavelength converter according to any one of claims 1 to 4, wherein the second semiconductor nanoparticle is composed of a core semiconductor containing Zn, Se, and Te and one or more shell semiconductors covering the core semiconductor.

6. The wavelength converter according to any one of claims 1 to 4, wherein the second semiconductor nanoparticle is composed of a core semiconductor containing Zn and P and one or more shell semiconductors covering the core semiconductor.

7. The wavelength converter according to any one of claims 1 to 4, wherein the second semiconductor nanoparticle is composed of a core semiconductor that is a compound having a chalcopyrite structure and one or more shell semiconductors covering the core semiconductor.

8. The second semiconductor nanoparticle is AgGaS ２ , AgInS ２ , AgGaSe ２ , AgInSe ２ , CuGaS ２ , CuGaSe ２ , CuInS ２ , ZnSiP ２ , ZnGeP ２ The wavelength converter according to any one of claims 1 to 4 and 7, characterized in that it is composed of a core semiconductor made of any one or more mixed crystal semiconductors selected from the group consisting of, and a single or a plurality of shell semiconductors covering the core semiconductor.

9. The wavelength converter according to any one of claims 5 to 8, wherein the shell semiconductor of the second semiconductor nanoparticle is composed of a II-VI group compound semiconductor.

10. The wavelength converter according to any one of claims 5 to 9, wherein the shell semiconductor of the second semiconductor nanoparticle is composed of any one or more mixed crystal semiconductors of ZnSe, ZnS, or the like.

11. The wavelength converter according to any one of claims 1 to 10, wherein the absorbance of a dispersion obtained by dispersing 1.0 mg of the first semiconductor nanoparticle in 1.0 mL of a solvent at an optical path length of 1 cm with respect to light having a wavelength of 450 nm is 0.7 or more.

12. The wavelength converter according to any one of claims 1 to 11, wherein the absorbance of a dispersion obtained by dispersing 1.0 mg of the second semiconductor nanoparticle in 1.0 mL of a solvent at an optical path length of 1 cm with respect to light having a wavelength of 450 nm is 1.0 or more.

13. The absorbance at an optical path length of 1 cm with respect to light having a wavelength of 450 nm of a dispersion liquid in which 1.0 mg of the second semiconductor nanoparticles are dispersed in 1.0 mL of a solvent is 1.2 or more, the wavelength converter according to any one of claims 1 to 12.

14. The absorbance at an optical path length of 1 cm with respect to light having a wavelength of 450 nm of a dispersion liquid in which 1.0 mg of the second semiconductor nanoparticles are dispersed in 1.0 mL of a solvent is 1.4 or more, the wavelength converter according to any one of claims 1 to 13.

15. The internal quantum efficiency of the first semiconductor nanoparticles is 70% or more, the wavelength converter according to any one of claims 1 to 14.

16. The internal quantum efficiency of the second semiconductor nanoparticles is 40% or more, the wavelength converter according to any one of claims 1 to 15.

17. The value of the mass ratio of the second semiconductor nanoparticles to the first semiconductor nanoparticles is 0.3 or less, the wavelength converter according to any one of claims 1 to 16.

18. A wavelength conversion material, characterized in that the wavelength converter according to any one of claims 1 to 17 is dispersed in a resin.

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