JP2013014715A - Fluoride phosphor and light-emitting device obtained using the fluoride phosphor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a red light-emitting phosphor that has an emission peak with a narrow half value width and a high luminous intensity, and a light-emitting device using the same.SOLUTION: The fluoride phosphor is represented by the general formula: KGeSiF; Mn(provided that x and y satisfy expressions: 0.4<(1-y)/y<5.0 and 0.80<(x+y)<0.99).

Description

  The present invention relates to a fluoride phosphor used for a light emitting diode, a display, a liquid crystal backlight, and the like, and a light emitting device using the same.

  A light emitting diode (LED) is a light emitting device often used as a substitute for another light source such as an incandescent lamp. The light emitting diode is useful as a display lamp, a warning lamp, a display lamp, and an illumination lamp. Various light emitting devices combining lasers (laser diodes: LD) with phosphors as well as light emitting diodes have been proposed. Both light emitting diodes and lasers are semiconductor light emitting devices produced from III-V group alloys such as gallium nitride (GaN). Various light emitting devices that emit light in white, light bulb color, orange color, etc. by combining the semiconductor light emitting element and the phosphor have been developed. These light emitting devices that emit white light and the like are obtained by the principle of light color mixing. As a method for emitting white light, a method using a light emitting element that emits ultraviolet light and three types of phosphors that emit RGB light, a method that uses a light emitting element that emits blue light, and a phosphor that emits yellow light, etc. Is well known. A light emitting device using a light emitting element that emits blue light and a phosphor that emits yellow light or the like is required in a wide range of fields such as lighting such as a fluorescent lamp, in-vehicle illumination, a display, and a backlight for liquid crystal. Among these, as a phosphor used for display applications, in order to reproduce a wide range of colors on the chromaticity coordinates, it is required to have good color purity as well as luminous efficiency. In particular, a phosphor used for display is required to have compatibility with a filter, and a phosphor having a narrow emission peak half-value width is required.

For example, as a red light-emitting phosphor having an excitation band in a blue region and a narrow half-value width of an emission peak, K ₂ TiF ₆ :: Mn ⁴⁺ , Ba ₂ TiF ₆ : Mn ⁴⁺ , Na ₂ TiF ₆ : Mn ⁴⁺ , K A fluoride phosphor having a composition such as ₃ ZrF ₇ : Mn ⁴⁺ is known (for example, see Patent Document 1). A fluoride phosphor of K ₂ SiF ₆ ,: Mn ⁴⁺ is also known (see, for example, Patent Document 2). Furthermore, the excitation / emission spectrum and emission mechanism of a Mn ⁴⁺ fluoride complex phosphor are also known (for example, see Non-Patent Document 1).

JP 2009-528429 A JP 2010-209111 A

A. G. Paulusz "Effective Mn (IV) Emission in Fluoride Coordination" J. Electrochemical Soc., 120 N7, 1973, p.942-947

However, conventionally, there has not been a red light emitting phosphor having a light emission peak with a narrow half-value width and high light emission intensity. In particular, the red light emitting Mn ^{4 +} -activated fluoride phosphor and the light emitting device using the same, which are suitable for display applications and have a narrow half-value width of the light emission peak, are desired to be put to practical use. Characteristics are not obtained.

  In view of the above, an object of the present invention is to provide a red-emitting phosphor having a high emission intensity with a narrow half-value width of an emission peak and a light-emitting device using the same, in order to solve the conventional problems.

  In order to solve the above-mentioned problems, the present inventors have intensively studied and as a result, the present invention has been completed.

  The present invention is a fluoride phosphor represented by the following general formula.

_{K 2 Ge x Si y F 6} : Mn 4+ 1-x-y
(However, x and y are 0.4 <(1-y) / y <5.0, 0.80 <x + y <0.99).
Thereby, the fluoride fluorescent substance according to the present invention has an emission spectrum with a narrow half-value width of an emission peak that is excited by blue light and emits light in the red region.

  The fluoride fluorescent material preferably has a hexagonal crystal structure belonging to the space group P63mc. Thereby, a fluoride fluorescent substance having high emission intensity can be provided.

  The present invention relates to a light-emitting device having a light source that emits blue light and the fluoride phosphor that absorbs the blue light and emits red light. In particular, in a display application, it is preferable to use a phosphor having a narrow emission peak half-width and high emission intensity.

  The fluoride phosphor preferably has an emission peak at 620 nm to 625 nm with a half width of 5 nm or less. This is because a brighter red light can be emitted.

  Since the present invention is configured as described above, it is possible to obtain a red light-emitting phosphor having good light emission characteristics, a narrow half-value width of a light emission peak, and a light emission intensity superior to that of the prior art. In addition, by using the phosphor obtained by the present invention, a light emitting device having a wider color reproduction range than the conventional one and excellent light emission characteristics can be obtained.

The X-ray-diffraction figure of the fluoride fluorescent substance of Example 1 and Comparative Examples 1 and 2 is shown. It is a graph of the emission spectrum when the phosphor according to Comparative Example 1 is excited at 460 nm. It is a graph of the emission spectrum when the phosphor according to Comparative Example 2 is excited at 460 nm. It is a graph of the emission spectrum when the phosphor according to Example 1 is excited at 460 nm.

  Hereinafter, a light-emitting device and a manufacturing method thereof according to the present invention will be described with reference to embodiments and examples. However, the present invention is not limited to this embodiment and example.

<First Embodiment>
<Light emitting device>
Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a phosphor, a light emitting device using the phosphor, and a method for manufacturing the phosphor for embodying the technical idea of the present invention. The manufacturing method of the body, the light emitting device using the same, and the phosphor is not specified as follows. In addition, the member shown by the claim is not what specifies the member of embodiment. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the constituent members described in the embodiments are not intended to limit the scope of the present invention only to the description unless otherwise specified. It is just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and symbol indicate the same or the same members, and detailed description thereof will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing. In addition, the contents described in some examples and embodiments may be used in other examples and embodiments.

  The relationship between the color name and chromaticity coordinates, the relationship between the wavelength range of light and the color name of monochromatic light, and the like comply with JIS Z8110. Specifically, 380 nm to 455 nm is blue purple, 455 nm to 485 nm is blue, 485 nm to 495 nm is blue green, 495 nm to 548 nm is green, 548 nm to 573 nm is yellow green, 573 nm to 584 nm is yellow, 584 nm to 610 nm is yellow red , 610 nm to 780 nm is red. In this specification, the light in the short wavelength region of visible light refers to a region of 400 nm to 500 nm, although not particularly limited.

  A light emitting device using the phosphor according to the embodiment will be described. The phosphor according to the present invention can be used in a conventional light emitting device. Examples of conventional light emitting devices include lighting devices such as fluorescent lamps, display devices such as displays and radars, backlights for liquid crystals, and the like. The fluoride phosphor according to the present invention is preferably used for display applications. Among these, a light emitting device including a light emitting element that emits light in a short wavelength region of visible light can be used as an excitation light source. In a light emitting device that covers an excitation light source with a sealing resin containing a phosphor, light emitted from the excitation light source is transmitted without being absorbed by the fluorescent material, and the transmitted light is emitted to the outside from the sealing resin. . When light on the short wavelength side of visible light is used as the excitation light source, the light emitted to the outside can be used effectively. Therefore, loss of light emitted from the light emitting device can be reduced, and a highly efficient light emitting device can be provided.

  There are various types of light emitting devices equipped with light emitting elements, such as a shell type and a surface mount type. In general, the bullet shape refers to a shape in which the shape of the resin constituting the outer surface is formed into a bullet shape. The surface-mounting type refers to one formed by filling a light-emitting element and a resin in a concave storage portion. Further, there is a type in which a light emitting element is mounted on a flat mounting substrate, and a sealing resin containing a phosphor is formed in a lens shape so as to cover the light emitting element.

(Light emitting element)
A light emitting element that emits light in a short wavelength region of visible light can be used. The range of 420 nm to 500 nm is particularly preferable. More preferably, it has an emission peak wavelength at 440 nm to 480 nm. This is because the phosphor according to the present invention can be excited efficiently and visible light can be effectively utilized. This is because a phosphor with high luminous efficiency can be provided by using an excitation light source in this range. In addition, by using a light emitting element as an excitation light source, a stable light emitting device with high efficiency, high output linearity with respect to input, and strong mechanical shock can be obtained. The light in the short wavelength region of visible light is mainly in the blue light region.

(Phosphor)
The fluoride phosphor according to the embodiment of the present invention is activated with tetravalent manganese, absorbs blue light, and emits red light. The fluoride fluorescent substance has a general formula of K ₂ Ge _x Si _y F ₆ : Mn ⁴⁺ _1-xy (where x and y are 0.4 <(1-y) / y <5.0, 0 .80 <x + y <0.99). The (Ge + Mn) / Si ratio in the present invention is represented by (1-y) / y in the above formula and is 0.4 or more and 5.0 or less, preferably 0.6 or more and 4.0 or less. More preferably, it is 0.9 or more and 3.5 or less. The activation amount of Mn ⁴⁺ is represented by 1-xy in the above formula, and is 1 mol% or more and 20 mol% or less, preferably 2 mol% or more and 10 mol% or less, more preferably 4 mol% or more, 8 mol. % Or less.

(Emission spectrum)
The fluoride phosphor absorbs light in the short wavelength side region of visible light, and has the emission peak wavelength of the phosphor on the longer wavelength side than the emission peak wavelength of excitation light. The light in the short wavelength region of visible light is mainly preferably in the blue light region. Specifically, it is excited by light from an excitation light source having an emission peak wavelength at 400 nm to 500 nm, has an emission peak wavelength in a wavelength range of 610 nm to 650 nm, and the half width of the emission spectrum is 3 nm or more and 8 nm or less. Preferably there is. As the excitation light source, a light source having a main emission peak wavelength at 420 nm to 500 nm is preferably used, and a light source having an emission peak wavelength at 440 nm to 480 nm is further preferably used. In addition, the phosphor of the present invention has an emission peak with a full width at half maximum of 5 nm or less at 620 nm to 625 nm when excited with light having a peak wavelength of 460 nm.

(X-ray diffraction measurement)
The fluoride phosphor has a hexagonal crystal structure belonging to the space group P63mc as a result of quantitative analysis by the RIR method in powder X-ray diffraction measurement (XRD) using Cu Kα ray, It is preferable to contain 80% by mass, more preferably 90% by mass or more.
(Other phosphors)
Although the fluoride fluorescent substance according to the present invention can be used alone, it can also be used in combination with other fluorescent substances. Any other phosphor may be used as long as it absorbs light from the light emitting element and converts it into light having a different wavelength. For example, nitride phosphors / oxynitride phosphors / sialon phosphors mainly activated by lanthanoid elements such as Eu and Ce, lanthanoid elements such as Eu, and transition metal elements such as Mn. Alkaline earth halogen apatite phosphor, alkaline earth metal borate phosphor, alkaline earth metal aluminate phosphor, alkaline earth silicate, alkaline earth sulfide, alkaline earth thiogallate Organic earth mainly activated by lanthanoid elements such as alkaline earth silicon nitride, germanate or rare earth aluminate, rare earth silicate or Eu mainly activated by lanthanoid elements such as Ce and It is preferably at least one selected from organic complexes and the like. For example, (Ca, Sr, Ba) ₂ SiO ₄ : Eu, (Y, Gd) ₃ (Ga, Al) ₅ O ₁₂ : Ce, (Ca, Sr) ₂ Si ₅ N ₈ : Eu, CaAlSiN ₃ : Eu, (Ca, Sr) AlSiN ₃ : Eu or the like.

  As a result, light emitting devices of various colors can be provided.

  Hereinafter, the fluoride fluorescent materials according to Examples 1 to 5 and Comparative Examples 1 and 2 will be described. Table 1 shows the charged amounts of the raw materials for the fluoride phosphors according to Examples 1 to 5 and Comparative Examples 1 and 2. FIG. 1 shows X-ray diffraction patterns of the fluoride phosphors of Example 1 and Comparative Examples 1 and 2. FIG. 2 is a graph of an emission spectrum when the phosphor according to Comparative Example 1 is excited at 460 nm. FIG. 3 is a graph of an emission spectrum when the phosphor according to Comparative Example 2 is excited at 460 nm. FIG. 4 is a graph of an emission spectrum when the phosphor according to Example 1 is excited at 460 nm.

(Comparative Example 1)
A fluoride phosphor according to Comparative Example 1 was produced by the following method.

First, 3.51 g of K ₂ MnF ₆ was weighed and dissolved in 240 g of 47% HF aqueous solution, and then 46.0 g of 40% H ₂ SiF ₆ aqueous solution was added to prepare Solution A. On the other hand, 19.94 g of KHF ₂ was weighed and dissolved in 50 g of a 47% HF aqueous solution to prepare a solution B. Solution B was added while stirring Solution A, and the resulting precipitate was separated, washed with IPA, and dried at 70 ° C. for 10 hours to produce the fluoride phosphor of Comparative Example 1.

From the X-ray diffraction pattern of the obtained fluoride phosphor of Comparative Example 1, it was confirmed that K ₂ SiF ₆ was synthesized.

(Comparative Example 2)
The fluoride phosphor according to Comparative Example 2 was produced by the following method.

A fluoride phosphor of Comparative Example 2 was produced in the same manner as Comparative Example 1 except that 60.0 g of 40% H ₂ GeF ₆ aqueous solution was added instead of 46.0 g of 40% H ₂ SiF ₆ aqueous solution.

From the X-ray diffraction pattern of the obtained fluoride phosphor of Comparative Example 2, it was confirmed that K ₂ GeF ₆ was synthesized.

Example 1
The fluoride phosphor according to Example 1 was produced by the following method.

Comparative Example 1 except that the amount of the H ₂ SiF ₆ aqueous solution and the H ₂ GeF ₆ aqueous solution added to the solution A was changed to 4.6 g of 40% H ₂ SiF ₆ aqueous solution and 54.0 g of 40% H ₂ GeF ₆ aqueous solution. The fluoride phosphor of Example 1 was produced in the same manner as described above.

From the X-ray diffraction pattern of the obtained fluoride phosphor of Example 1, it was found that K ₂ Ge _0.70 Si _0.24 F ₆ : Mn ⁴⁺ _0.06 different from Comparative Examples 1 and 2 was synthesized. I was able to confirm. It was confirmed that the fluoride phosphor of Example 1 contained 96% by mass of a hexagonal crystal structure belonging to the space group P63mc, which was different from Comparative Example 1 and Comparative Example 2.

  Further, from the emission spectrum of the obtained phosphor, it was confirmed that the half-width was 3 nm having an emission peak in the range of 618 nm to 624 nm.

(Examples 2 to 5)
Fluoride phosphors of Examples 2 to 5 were produced in the same manner as in Comparative Example 1 except that the amounts of the H ₂ SiF ₆ aqueous solution and the H ₂ GeF ₆ aqueous solution added to the solution A were changed. Fluoride phosphor after fabricated, Example _{2 K 2 Ge 0.53 Si 0.41 F} 6: Mn 4+ 0.06, Example _{3 K 2 Ge 0.43 Si 0.51 F} 6: Mn ⁴⁺ _0.06, Example 4 was K ₂ Ge _0.34 Si _0.60 F ₆ : Mn ⁴⁺ _0.06, Example 5 was K ₂ Ge _0.27 Si _0.69 : Mn ⁴⁺ _0.05 It was.

(Measurement result)
About the obtained fluorescent substance which concerns on Examples 1-5 and Comparative Examples 1 and 2, the result of having performed the composition analysis by ICP, a luminance characteristic, etc. are shown. Table 2 shows the luminance characteristics, X-ray diffraction measurement, and composition analysis results of the fluoride phosphors according to Examples 1 to 5 and Comparative Examples 1 and 2. The relative luminance of Comparative Example 2 and Examples 1 to 5 when the luminance of Comparative Example 1 is 100% is shown.

As described above, Examples 1 to 5 have higher emission luminance than Comparative Examples 1 and 2. In particular, Examples 1 to 4 showed higher light emission luminance than Comparative Examples 1 and 2. Moreover, it has confirmed that the hexagonal crystal structure which belongs to the space group P63mc in the X-ray diffraction which concerns on Examples 1-4 contains 41 mass%-100 mass%. In particular, it was confirmed that the hexagonal crystal structure belonging to the space group P63mc in the X-ray diffraction according to Examples 1 to 3 contained 96% by mass to 100% by mass.

  Fluorescent phosphors of the present invention and light emitting devices using them are backlights that are extremely excellent in light emission characteristics using fluorescent light emitting diodes, such as fluorescent display tubes, displays, PDPs, CRTs, FLs, FEDs, projection tubes, etc. It can be used for light sources, LED displays, white illumination light sources, traffic lights, illumination switches, various sensors, various indicators, and the like, and exhibits excellent emission characteristics particularly in display applications.

Claims (4)

A fluoride phosphor represented by the following general formula.
_{K 2 Ge x Si y F 6} : Mn 4+ 1-x-y
(However, x and y are 0.4 <(1-y) / y <5.0, 0.80 <x + y <0.99). The fluoride phosphor according to claim 1, wherein the fluoride phosphor has a hexagonal crystal structure belonging to the space group P63mc. The light-emitting device which has a light source which emits blue light, and the fluoride fluorescent substance of Claim 1 which absorbs this blue light and light-emits red. The light emitting device according to claim 3, wherein the fluoride fluorescent material has a light emission peak with a full width at half maximum of 5 nm or less from 620 nm to 625 nm.

Images