JP2017155071A - Fluophor and manufacturing method therefor, wavelength conversion membrane using the fluophor, solar cell module and light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a SrCaGaS:Eu fluophor (0<x<1) having particle size of 1000 nm or less and high crystallinity, a solar cell high in conversion efficiency or a light emitting device such as a white LED high in light emission efficiency by using the fluophor.SOLUTION: A fluophor is manufactured by (a) a process for manufacturing a raw material particle containing a constitutional unit of the base material excluding a sulfur component and a constitutional unit of the activator at a composition ratio in the fluophor, (b) a process for manufacturing an amorphous precursor particle by heating the raw material particle by thermal plasma and cooling the same and (c) a process for burning the precursor particle under a sulfurizing atmosphere at a first temperature of a sulfurizing temperature or higher and less than a crystallization temperature and then burning the same at a second temperature of the crystallization temperature or higher.SELECTED DRAWING: None

Description

  The present invention relates to a particulate phosphor that absorbs light in the ultraviolet to green region and emits light of a specific wavelength, and a method for producing the same, and further, a wavelength conversion film and a solar cell using the phosphor The present invention relates to a module and a light emitting device.

Conventionally, as phosphors having high luminous efficiency, phosphors based on thiogallate sulfides represented by SrGa ₂ S ₄ : Eu or CaGa ₂ S ₄ : Eu are known, and alkaline earth metal species are known. It is known that light emission of various wavelengths can be obtained by changing. Further, Patent Document 1 discloses that SrGa ₂ having a particle size of 1000 nm or less and a crystallite size of 60% or more of the particle size is obtained by nano-forming precursor fine particles with thermal plasma and then heat-treating in hydrogen sulfide. A method for producing S ₄ : Eu or CaGa ₂ S ₄ : Eu is disclosed.
On the other hand, Patent Document 2 discloses that the emission wavelength is between 535 nm and 560 nm by adjusting x of a phosphor containing Sr and Ca, which is represented by Sr _x Ca _1-x Ga ₂ S ₄ : Eu. It is disclosed that light emission with a wavelength of can be obtained.

JP 2012-36372 A JP-T-2006-524437

In the phosphor used for the wavelength conversion film of a solar cell or a white LED, a technique for precisely controlling the absorption wavelength and the emission wavelength is required according to each application. Also, if you want to convert a specific wavelength and allow light of other wavelengths to pass through without being scattered, like a solar cell wavelength conversion film, a phosphor with small particle size and excellent crystallinity is required. It becomes. Therefore, a method for producing a Sr _x Ca _1-x Ga ₂ S ₄ : Eu phosphor having a particle size of 1000 nm or less capable of controlling the emission wavelength by the mixing ratio of Sr and Ca has been desired.
However, Patent Document 1, 1000 nm or less in particle size _{Sr x Ca 1-x Ga 2} S 4: production method of Eu phosphor is not disclosed. Moreover, with the manufacturing method disclosed in Patent Document 2, it is not possible to manufacture the Sr _x Ca _1-x Ga ₂ S ₄ : Eu phosphor with a small particle size.
An object of the present invention is to provide a Sr _x Ca _1-x Ga ₂ S ₄ : Eu phosphor (0 <x <1) having a particle size of 1000 nm or less and high crystallinity, An object of the present invention is to provide such a phosphor as particles having high uniformity in particle size. Another object of the present invention is to provide a solar cell having a high conversion efficiency and a light emitting device such as a white LED having a high light emission efficiency by using the phosphor.

The present invention is a particulate phosphor containing a thiogallate sulfide matrix material represented by the following general formula (1), and an activator,
The particle size is 1000 nm or less, and the volume ratio of the crystal phase in the particle is represented by the following general formula (2).
_{Sr x Ca 1-x Ga 2} S 4 ( where, 0 <x <1) ( 1)
Vc / Vt ≧ (R−10) ³ / R ³ (2)
(In the above formula (2), Vc is the volume of the crystal phase in the particle, Vt is the volume of the particle, and R is the particle size)
Further, the present invention is a wavelength conversion film characterized by dispersing the phosphor of the present invention, and a solar cell module and a light emitting device characterized by using the phosphor of the present invention.

In the present invention, by calcining a precursor in two steps, a phosphor having a particle size as small as 1000 nm or less and high crystallinity and using Sr _x Ca _1-x Ga ₂ S ₄ as a base material is provided. Can do. Therefore, in the member or apparatus using the phosphor of the present invention, the emission wavelength can be precisely controlled, the scattering of light other than the absorption wavelength can be reduced, and high emission luminance can be obtained.
Furthermore, in the present invention, in the precursor firing step, by setting the second temperature to 700 ° C. or lower, the particle size of the phosphor can be made less than 250 nm, and the light scattering can be further reduced. An apparatus can be provided. Also, in the precursor firing step, the particle size distribution of the phosphor can be made narrower by slowing the rate of temperature rise to the first temperature and the second temperature over time, and more light scattering It is possible to provide a member or a device that reduces the above.
Furthermore, in the present invention, by using an oxide of an activator as a raw material, the impurity of the obtained phosphor can be reduced to 200 ppm or less, and a decrease in luminance due to the impurity can be suppressed.
Therefore, in the present invention, there are provided a wavelength conversion film in which scattering of light other than the absorption wavelength is reduced, and a light emitting device such as a solar cell with high conversion efficiency and a white LED with high light emission efficiency.

It is sectional drawing of the thickness direction which shows typically the structure of embodiment of the solar cell module using the fluorescent substance of this invention. It is sectional drawing of the thickness direction which shows typically the structure of white LED using the fluorescent substance of this invention.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments described below. Further, in the present invention, the scope of the present invention also includes those in which the embodiments described below are appropriately modified and improved based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. include.

(Phosphor)
The phosphor of the present invention is a particulate phosphor containing a thiogallate sulfide base material represented by the following general formula (1) and an activator.
_{Sr x Ca 1-x Ga 2} S 4 ( where, 0 <x <1) ( 1)

The phosphor of the present invention has a particle size of 1000 nm or less, and the volume ratio of the crystal phase in the particles is represented by the following general formula (2). In the following formula (2), Vc is the volume of the crystal phase in the particle, Vt is the volume of the particle, and R is the particle size.
Vc / Vt ≧ (R−10) ³ / R ³ (2)

  The particle size in the present invention refers to D50 (median diameter) obtained by measuring the particle size distribution by dynamic light scattering (DLS). D50 can be measured, for example, using “ZETASIZER (Nano-ZS)” manufactured by Malvern Instruments from a dispersion in which a phosphor is dispersed in ethanol.

  In addition, the phosphor of the present invention has an amorphous layer and a crystal phase covered with the amorphous layer. In a transmission electron microscope (TEM) observation, the amorphous layer is The average thickness is 5 nm or less. Therefore, the volume ratio of the crystal phase of the phosphor of the present invention is represented by the general formula (2). When the amorphous layer becomes thicker than 5 nm in the whole particle, the luminance of the phosphor having a small particle size is particularly lowered. For example, when the particle size is 50 nm and the average thickness of the amorphous layer is 6 nm, more than half of the particles become an amorphous layer and the luminance is significantly reduced. In the present invention, as long as the average thickness of the amorphous layer is 5 nm or less, it may partially exceed 5 nm.

When the phosphor as in the present invention is used for the wavelength conversion material, the wavelength conversion characteristics for absorbing and emitting specific light and the transmission characteristics for transmitting non-absorbed light with as little scattering as possible are important.
First, in the solar cell, a wavelength conversion characteristic for absorbing a specific wavelength and converting it to another wavelength is required to convert a wavelength with low power generation efficiency into a wavelength with high power generation efficiency, depending on the type of solar cell to be used. It is done. For example, SrGa ₂ S ₄ having Eu as the emission center absorbs light in the ultraviolet to blue region and emits light having a peak wavelength of 532 nm. Similarly, CaGa ₂ S ₄ having Eu as the emission center absorbs light in the ultraviolet to green region and emits light having a peak wavelength of 555 nm. And if it is a solar cell with high sensitivity in the middle wavelength, it can be realized with Sr _x Ca _1-x Ga ₂ S _{4 in} which Sr and Ca are mixed. Also for the white LED, the light emission characteristics can be controlled by a phosphor in which a light emission center is added to Sr _x Ca _1-x Ga ₂ S ₄ in accordance with a required color tone.

  And as said transmission characteristic, if it is a wavelength conversion use of a solar cell, it is necessary to permeate | transmit the light of a wavelength with high electric power generation efficiency without being scattered by a fluorescent substance from the first. In addition, for white LED applications, a part of the light emitted from the LED chip is absorbed and converted to other wavelengths, but if the scattering of the light can be reduced, higher light emission efficiency than before can be obtained. It is done.

  In general, it is known that the degree of scattering is maximized at a particle size approximately half the wavelength of the irradiation light. Here, considering the use of solar cells, the sunlight spectrum on the ground surface has the maximum intensity around 500 nm, so that the scattering of sunlight is maximized when the particle size is 250 nm (Mie scattering). . It is known that when the particle size of the phosphor is smaller than 250 nm, the scattering component is dominated by Rayleigh scattering, and the smaller the particle size, the smaller the scattering. On the other hand, even in the range where the particle size of the phosphor is larger than 250 nm, the degree of scattering is reduced although the degree is small compared to the small particle size. When using a phosphor for wavelength conversion, a wavelength conversion film is mainly formed by molding a resin composition in which the phosphor is dispersed in a transparent resin. If the particle size of the phosphor is too large, the wavelength conversion film is used. Therefore, the manufacturing method is difficult. In addition, when the particle size of the phosphor is large, there is a problem that the phosphor component in the wavelength conversion film increases and the function as the original resin is impaired. Therefore, a particle size of about 500 nm or less is preferable. Therefore, in the phosphor of the present invention, the particle size is preferably greater than 250 nm and less than or equal to 500 nm or less than 250 nm in view of light transmission characteristics. Further, when the particle size of the phosphor is reduced, the ratio of the crystal phase in the phosphor particles is reduced. When the particle size is less than 50 nm, it is difficult to make the volume ratio of the crystal phase in the particle 50% or more, and the luminance is lowered. Therefore, the particle size is preferably 50 nm or more. Therefore, a more preferable particle size of the phosphor of the present invention is 50 nm or more and less than 250 nm at which scattering is reduced in a wide wavelength range.

Next, the crystallinity of the phosphor particles will be described. Whether or not it is a crystalline substance having a desired composition can typically be determined by X-ray diffraction measurement, and whether or not a Sr _x Ca _1-x Ga ₂ S ₄ crystal can be synthesized from the diffraction line profile. Can be confirmed. The size of the crystal phase can be confirmed by TEM (transmission electron microscope) observation, electron diffraction analysis, or the like.

Host material of the phosphor of the present invention are those represented by _{Sr x Ca 1-x Ga 2} S 4, composition ratio of Sr and Ca, i.e. x can be selected depending on the application. As the wavelength conversion material of the solar cell, the composition ratio of Sr and Ca is selected according to the wavelength to be converted. Moreover, also when using for white LED, the composition ratio of Sr and Ca is selected so that it may become a suitable color tone in combination with a blue LED chip. As the activator, for example, Eu, Ce and the like can be used, but a combination with Eu is preferable. The activator Ce or Eu is added by replacing a part of Sr and Ca. The concentration can be selected from the range of, for example, 0.1 mol% to 15 mol% with respect to the total amount of Sr, Ca, and Eu, but 0.5 mol% to 7 mol% because high luminance is easily obtained. It is preferable to select within the range.

(Phosphor production method)
The phosphor according to the present invention can be manufactured through the following steps (a) to (c). Step (a) is a step of producing raw material particles containing the constituent components of the base material excluding the sulfur component and the constituent components of the activator at a predetermined composition ratio (composition ratio in the phosphor). Step (b) is a step of producing amorphous precursor particles by heating and cooling the raw material particles with thermal plasma. Step (c) is a step of firing the precursor particles in a sulfurizing atmosphere to produce sulfide crystal particles.

First, in step (a), each component alone or a compound containing each component is used so that the Sr component, Ca component, Ga component, and activator component constituting the phosphor have a composition ratio in the phosphor to be produced. The raw materials are weighed, mixed, and fired.
For example, when producing Sr _0.5 Ca _0.5 Ga ₂ S ₄ : Eu, strontium carbonate (SrCO ₃ ), calcium carbonate (CaCO ₃ ), gallium oxide (Ga ₂ O ₃ ), and europium oxide (Eu ₂ O _3). ) Can be used as a raw material. When Eu is 2 mol% with respect to the total molar concentration of Sr, Ca and Eu (containing 0.02 mol of Eu with respect to a total of 1 mol of Sr, Ca and Eu), these raw materials are used as Sr and Ca. And the mixture is fired so that the molar composition ratio of Ga, Ga and Eu is 0.49: 0.49: 2: 0.02.
Firing is performed as long as particles in which Sr, Ca, Ga, and Eu are uniformly diffused are produced, and the firing is performed at a temperature of 900 ° C. to 1200 ° C. for about 0.5 hours to 5 hours. At this time, the particle size of the raw material particles to be synthesized is preferably 1 μm to 30 μm.

  Next, in the step (b), the raw material particles are subjected to thermal plasma treatment with a high-frequency thermal plasma apparatus to produce precursor particles. The precursor particles can be obtained as nano-level particles by putting raw material particles into thermal plasma generated in a plasma torch to form droplets, and then rapidly cooling the droplets from the droplets in a chamber. Plasma is generated by applying a high frequency to the plasma torch. The frequency of the high frequency used is about 0.1 MHz to 5 MHz. The pressure in the torch only needs to be maintained at a pressure equal to or lower than atmospheric pressure, and can be set to 660 Pa to 100,000 Pa, for example. Examples of the gas for generating plasma include argon, nitrogen, hydrogen, oxygen, or a mixed gas thereof. By supplying the raw material particles together with a sufficient amount of carrier gas, it is possible to rapidly cool the droplets from a droplet state. The supply amount of the carrier gas is preferably set so that the average flow velocity in the chamber is about 0.1 m / sec to 20 m / sec. As the carrier gas, argon, nitrogen, hydrogen, oxygen, or a mixed gas thereof can be used. The precursor particles are collected by a collection filter connected to the chamber and a vacuum pump. By adjusting the flow rate and power of the gas supplied to the high-frequency thermal plasma apparatus, precursor particles having a particle size of 8 nm to 50 nm can be obtained. The precursor particles preferably have a particle size of 50 nm or less, more preferably 30 nm or less.

  In the step (c), the above precursor particles are calcined and crystallized by firing in a sulfurizing atmosphere. Thereby, a phosphor having a particle size of 1000 nm or less and high crystallinity can be obtained. Specifically, the precursor particles are filled in a quartz crucible or quartz tray, and heated to a temperature equal to or higher than the crystallization temperature of the precursor particles while flowing hydrogen sulfide gas, thereby producing a phosphor. Can do. When the precursor is crystallized in an oxide state, it is difficult to replace it with sulfide at a low temperature. Therefore, the firing process includes a sulfurization process for sulfiding the amorphous precursor of the oxide and a sulfided amorphous material. It is produced in two steps, a crystallization step for crystallization of quality particles. That is, in a sulfur atmosphere, the precursor particles are fired at a first temperature not lower than the crystallization temperature and lower than the crystallization temperature, and then fired at a second temperature not lower than the crystallization temperature. Each temperature varies depending on the type of the precursor, but generally the first temperature in the sulfiding step is 450 ° C. or higher and 530 ° C. or lower, and preferably 470 ° C. or higher and 520 ° C. or lower. The second temperature in the crystallization step is 550 ° C. or higher and 1000 ° C. or lower, and preferably 590 ° C. or higher and 900 ° C. or lower. The particle size of the phosphor can be controlled by the crystallization temperature and the holding time. In the present invention, the particle size of the phosphor can be made less than 250 nm by setting the second temperature to 550 ° C. or more and 700 ° C. or less.

  The temperature profile in the step (c) is a two-stage temperature profile in the range of 450 ° C. or higher and 1000 ° C. or lower as described above. The temperature at the first stage in the two-stage temperature profile is a temperature for changing the oxide precursor particles to sulfide, and is a temperature lower than the temperature at which the oxide crystallizes at a temperature equal to or higher than the sulfurization temperature of the precursor particles. The sulfiding temperature is a temperature at which sulfiding of precursor particles starts in a sulfiding atmosphere, and differs depending on the type of the precursor. Further, the holding time varies depending on the amount of the precursor and the apparatus configuration, but is held for a fixed time from several minutes to several hours. The temperature at the second stage is a temperature for crystallizing the precursor particles and is a temperature equal to or higher than the crystallization temperature. The treatment temperature and the holding time vary depending on the type of necessary phosphor and the required particle size, and may be held for several minutes or may be held for several hours. The reason why the processing temperature in the sulfurized atmosphere is raised in two stages will be described in more detail.

  In order to form a phosphor having a desired size of 1000 nm or less, it is necessary to complete the sulfiding and crystallization processes at a low temperature. As a result of examining the sulfurization reaction of the precursor particles in detail, it was found that when the amorphous and crystalline precursor particles were compared, the amorphous precursor particles proceeded to sulfidation at a lower temperature. Under the processing conditions in which the temperature is continuously increased, oxide particles are formed before the precursor particles to be processed are completely converted to sulfides, and are not easily sulfided within a predetermined temperature range. As a result, the amount of oxide crystallized particles increases. If it is crystallized in the oxide state, it becomes difficult to sulfidate the precursor particles at a low temperature, and if treated at a high temperature for sulfidation, the particle size increases. In other words, by setting a two-stage temperature profile that completely sulfidates the precursor particles before reaching the crystallization temperature, a homogeneous and highly crystalline sulfide phosphor controlled to the desired particle size can be obtained. Can be formed.

  In the step (c), when the temperature of the phosphor itself during firing was monitored, it was confirmed that the phosphor might have a temperature higher than the set temperature due to the influence of reaction heat generated during sulfidation and crystallization. When the dissociation between the set temperature and the actual temperature increases, it may be difficult to control the particle size and its uniformity. Therefore, in step (c), it is preferable to perform firing so as not to exceed the set value while monitoring the actual temperature of the phosphor. For example, a phosphor having a uniform particle size distribution can be obtained by directly setting a thermocouple such as a tungsten rhenium alloy in a precursor powder set in a firing furnace and firing it while measuring the temperature. Also, without setting a thermocouple in the phosphor powder, the temperature rising rate is set to be slower over time in the temperature rising process to the first temperature and the temperature rising process to the second temperature. Thus, firing may be performed with moderate self-heating.

  In this way, phosphor particles having a narrow particle size distribution can be synthesized by optimizing the firing conditions in step (c). As a result of particle size measurement by DLS, there is PDI (polydispersity index), which is known as an index indicating uniformity of particle size. This is expressed in the range of 0 to 1, where 0 means an ideal single size particle with no particle size distribution. Monodisperse particles with a PDI of 0.1 or less, and dispersions having a value between more than 0.1 and 0.3 or less are known to have a narrow particle size distribution. When PDI is more than 0.3 and 0.5 or less, it is considered that the particle size distribution is relatively wide, and when PDI is larger than 0.5, the dispersion is considered to be polydispersed. As a fluorescent substance used for a solar cell or LED, PDI is preferably 0.5 or less, more preferably 0.3 or less. In the present invention, the temperature increase rate in the temperature increase process of the step (c) is specifically increased at a constant temperature increase rate so as to slow down with time, and the first temperature, When the temperature approaches the temperature, the PDI can be controlled to 0.3 or less by decreasing the rate of temperature rise.

  In addition, in order to obtain high-luminance phosphor particles, it is extremely important to manage impurities other than the constituent elements in the phosphor. In particular, the influence of impurities is large in a phosphor having a small particle diameter. In a small particle size phosphor having a particle size of 1000 nm or less, when the amount of impurities other than the constituent elements exceeds 200 ppm, it becomes clear that the luminance of the small particle phosphor is remarkably lowered, and is preferably set to 200 ppm or less. . More preferably, 100 ppm or less is preferable. There are several factors of impurity contamination. For example, a bead element may be mixed when a phosphor having a large particle size is physically pulverized by a bead mill method. In addition, there may be mentioned a case where a chloride or fluoride raw material is used when the raw material particles are synthesized, a case where a flux composed of a halide is added, and firing is performed. These halogen elements finally remain in the phosphor particles and lower the luminance. In the present invention, since a physical pulverization process is not performed, contamination of impurities due to the process can be avoided. Moreover, in this invention, by using an oxide as an activator component, the impurity in a fluorescent substance can be 200 ppm or less, and the luminance fall resulting from an impurity can be suppressed.

(Solar cell)
Next, a solar cell using the phosphor of the present invention will be described.
FIG. 1 is a schematic cross-sectional view in the thickness direction showing a configuration example of a solar cell module using the phosphor of the present invention. In the solar cell module, a front glass 5, a sealing material 6, solar cells 7, and a back sheet 8 are arranged on the side on which sunlight enters (upward in the drawing). Reference numeral 1 denotes a wavelength conversion film in which the phosphor particles 3 of the present invention are dispersed in a transparent resin. As the transparent resin, EVA (ethylene-vinyl acetic acid copolymer), PVB (polyvinyl butyral resin), silicone resin, or the like is used. However, the transparent resin is not limited to this as long as it has both sunlight permeability and durability. Since the phosphor particles 3 of the present invention are dispersed, the wavelength conversion film 1 absorbs light in a region corresponding to the wavelength conversion characteristics of the phosphor and emits light in a higher wavelength region.

  The sealing material 6 is made of a transparent resin, has a function as a protective film for preventing moisture such as rain and snow, and is disposed so as to cover the solar battery cell 7. As the solar battery cell 7, various solar battery cells such as a single crystal silicon solar battery, a polycrystalline silicon solar battery, an amorphous silicon solar battery, and other compound semiconductor solar batteries can be used. One or a plurality of these solar cells are sealed in the sealing material 3 in a state where they are electrically connected.

  The wavelength conversion film 1 may be attached to the front surface of the solar battery cell 7 as shown in FIG. 1A because the wavelength may be converted before the sunlight reaches the solar battery cell 7. Moreover, you may arrange | position on the front surface or the back surface of the front glass 5 in the state which sealed the photovoltaic cell 7 with the sealing materials 6 and 6 like FIG.1 (b) and FIG.1 (c). Furthermore, as shown in FIG. 1 (d), the wavelength conversion film 1 may be attached to each solar battery cell 7 and sealed with the sealing materials 6 and 6. In the solar cell module, an antireflection film (not shown) may be provided on the front surface of the front glass 5 irradiated with sunlight. In this case, the wavelength conversion film 1 may be disposed on either the front surface or the back surface of the antireflection film. Further, the phosphor 3 may be dispersed in the wavelength prevention film, and the wavelength conversion film and the antireflection film may be used together.

  The phosphor of the present invention is superior in crystallinity and has high wavelength conversion characteristics as compared with conventional phosphors of the same size. Furthermore, the particle size distribution is narrow, and there are few particles having a size greatly deviating from the design value. For this reason, in the solar cell module using the phosphor of the present invention, the scattering of light of wavelengths other than the wavelength to be converted is small, and the power conversion efficiency of the solar cell can be improved.

(Light emitting device)
The phosphor of the present invention is also preferably applied to a light emitting device, and specifically, is suitably used for a white LED. FIG. 2 is a schematic cross-sectional view in the thickness direction showing a configuration example of a white LED using the phosphor of the present invention.
The white LED in FIG. 2 includes an LED chip 10 as a light source. As the white lamp, a semiconductor light emitting element such as a light emitting diode or a laser diode having a peak emission wavelength in the range of 370 nm to 470 nm is used. As the LED chip 10, various light emitting diodes such as InGaN, GaN, and AlGaN are used. The emission wavelength of this light source preferably has a peak wavelength in the range of 370 nm to 490 nm. A white LED is formed by combining such an LED chip 10 and a phosphor that absorbs part of the light emitted from the LED chip 10 and converts it to another wavelength (blue, green, red, or yellow) to emit light. can do. In the phosphor of the present invention, an appropriate composition ratio of Sr and Ca can be selected according to the required color tone.

  The LED chip 10 is mounted on the substrate 11 via various wirings 12. A cylindrical frame 13 is installed on the substrate 11, and a reflective layer is provided inside the frame 13. The electrodes of the LED chip 10 are electrically connected to the wiring 12 on the substrate 11 by bonding wires 14. The frame 13 is filled with a transparent resin layer 15, and the LED chip 10 is embedded in the transparent resin layer 15. In the example of FIG. 2A, the phosphor particles 3 of the present invention are dispersed in the transparent resin layer 15 in order to obtain white light. The dispersed phosphor particles 3 absorb a part of the light emitted from the LED chip 10 and are excited to emit light, and these lights are combined to obtain white light.

  The phosphor particles 3 do not necessarily have to be dispersed in the transparent resin layer 15. For example, as shown in FIG. 2B, the wavelength conversion layer 16 in which the phosphor particles 3 are dispersed on the transparent resin layer 15 is provided. It may be provided. In the wavelength conversion layer 16, the phosphor particles 3 may be dispersed in a transparent resin, or may be dispersed in an inorganic transparent material such as glass. As shown in FIG. 2C, the phosphor particles 3 may be coated on a transparent layer 17 made of a transparent resin or an inorganic transparent material. The transparent resin used for the transparent resin layer 15, the wavelength conversion layer 16, or the transparent layer 17 is the same EVA (ethylene-vinyl acetate copolymer), PVB (polyvinyl butyral resin), silicone resin, and the like as the solar cell module. Is preferably used.

Since the phosphor of the present invention is a phosphor that absorbs ultraviolet rays and emits green to yellow-green, white light emission can be obtained by using it in combination with other phosphors emitting blue or red.
The phosphor of the present invention is superior in crystallinity and has high emission characteristics as compared with a conventional phosphor of the same size. Furthermore, the particle size distribution is narrow, and there are few particles having a size greatly deviating from the design value. Therefore, there is little scattering of light from the light source or light emitted from the phosphor, and white light can be obtained with high efficiency.

[Example 1]
A phosphor represented by Sr _0.9 Ca _0.1 Ga ₂ S ₄ : Eu was produced by the production method of the present invention. As raw materials, strontium carbonate powder (SrCO ₃ ), calcium carbonate (CaCO ₃ ), gallium oxide powder (Ga ₂ O ₃ ) and europium oxide powder (Eu ₂ O ₃ ) are used, and these powders are mixed using a mortar. did. At this time, the constituent components of the base material excluding the sulfur component were weighed so as to have a composition ratio in the phosphor to be produced. The molar concentration of Eu in the obtained phosphor was 2% with respect to the total molar concentration of Sr, Ca, and Eu. The mass ratio of each raw material is as follows.
SrCO ₃ : CaCO ₃ : Ga ₂ O ₃ : Eu ₂ O ₃ ≈3.84: 0.29: 5.54: 0.10

Next, the mixed powder was put in an alumina crucible, set in an air atmosphere, and fired in an atmosphere of 1050 ° C. for 2 hours to produce raw material particles. When the particle size distribution of the raw material particles was measured, D50 was 7.6 μm as a result of particle size measurement by DLS.
Next, the produced raw material particles were processed into a nanosize by a high-frequency thermal plasma method to produce a precursor. Argon gas was introduced into the high-frequency thermal plasma apparatus at a flow rate of 80 L / min (L is liter). In order to generate plasma, power of about 4 MHz and 80 kVA was applied to the high frequency oscillation coil to generate thermal plasma. The raw material particles described above were introduced into the thermal plasma apparatus thus adjusted together with argon as the carrier gas, and the precursor fine particles produced by melting and cooling were collected. As a result of observing the obtained particles with SEM, it was found that the particles had a particle size of about 20 nm. As a result of analyzing the crystal structure by XRD, it was found to be amorphous.

  Next, the produced precursor particles were fired. The firing atmosphere was a 3% hydrogen sulfide gas atmosphere diluted with argon, and 25 g of precursor particles were fired in a two-stage temperature profile to produce a phosphor. In the two-stage temperature profile, the sulfidation temperature as the first temperature was 500 ° C., and the crystallization temperature as the second temperature was 620 ° C. The heating rate up to the first temperature was 10 ° C./min, and the holding time at 500 ° C. was 2 hours. Subsequently, the rate of temperature increase to the second temperature was 10 ° C./min, and the holding time at 620 ° C. was 10 minutes.

In the particle size distribution measurement by DLS of the phosphor thus produced, the particle size (D50) was 113 nm and the polydispersity index (PDI) was 0.39. Moreover, as a result of analyzing the crystal structure in a Rigaku XRD diffractometer, it was confirmed that it was a single phase of Sr _0.9 Ca _0.1 Ga ₂ S ₄ crystal. Further, when the cross section of the particle was observed with a TEM, it was confirmed that the surface layer of the particle of about 4 nm had an amorphous structure, but other than that was a crystalline phase. As a result of elemental analysis by ICP-MS (inductively coupled plasma mass spectrometry), elements other than the constituent elements were below the detection limit.
The light emission characteristics of the phosphors were evaluated. 0.5 g of powder was filled in a measurement cell, set in a spectrofluorometer (manufactured by Hitachi High-Tech, F-4500), and an excitation spectrum and an emission spectrum were measured. As a result, green fluorescence having light absorption in a wide wavelength range from the ultraviolet region to blue color and having a peak wavelength at 537 nm was confirmed.

[Examples 2 to 6]
A phosphor was synthesized in the same manner as in Example 1 except that the composition of the raw materials was changed so that the composition ratio shown in Table 1 was obtained. The obtained phosphor particle size, polydispersity index, relative luminance with respect to the phosphor of Example 1 (relative value with the luminance of the phosphor of Example 1 being 100), and the thickness (average) of the amorphous layer The results analyzed in the same manner as in Example 1 are shown in Table 1.

[Examples 7 to 11]
A phosphor was synthesized in the same manner as in Example 3 except that the second temperature condition in the step (c) was changed as shown in Table 1. Table 1 shows the results of analyzing the particle size, polydispersity index, relative luminance of the phosphor of Example 1 and the thickness (average) of the amorphous layer in the same manner as in Example 1 of the obtained phosphor.

Example 12
In the same manner as in Example 1, precursor particles were formed. Next, the produced precursor particles were fired. The firing atmosphere was a 3% hydrogen sulfide gas atmosphere diluted with argon, and 25 g of precursor particles were fired with a two-stage temperature profile to produce a phosphor. In the two-stage temperature profile, the sulfidation temperature as the first temperature was 500 ° C., and the crystallization temperature as the second temperature was 620 ° C. The rate of temperature increase to the first temperature was 10 ° C./min from 450 ° C., 3 ° C./min from 450 ° C. to 500 ° C., and the holding time at 500 ° C. was 2 hours. Subsequently, the rate of temperature increase to the second temperature was 10 ° C./min from 570 ° C. to 3 ° C./min from 570 ° C. to 620 ° C., and the holding time at 620 ° C. was 10 minutes.

The phosphor thus produced was analyzed in the same manner as in Example 1. As a result, the particle size was 99 nm and the polydispersity index was 0.26. Further, a single phase of Sr _0.9 Ca _0.1 Ga ₂ S ₄ crystal, but the surface layer of about 5nm particles had become amorphous structure, otherwise it could be confirmed that a crystalline phase.

[Examples 13 to 17]
A phosphor was synthesized in the same manner as in Example 12 except that the composition of the raw material was changed so that the composition ratio shown in Table 1 was obtained. Table 1 shows the results of analyzing the particle size, polydispersity index, relative luminance of the phosphor of Example 1 and the thickness (average) of the amorphous layer in the same manner as in Example 1 of the obtained phosphor.

[Examples 18 to 22]
A phosphor was synthesized in the same manner as in Example 14 except that the second temperature condition in the step (c) was changed as shown in Table 1. Table 1 shows the results of analyzing the particle size, polydispersity index, relative luminance of the phosphor of Example 1 and the thickness (average) of the amorphous layer in the same manner as in Example 1 of the obtained phosphor.

[Comparative Example 1]
Precursor particles were produced under the same conditions as in Example 1. Next, 25 g of the precursor particles were fired in a 3% hydrogen sulfide gas atmosphere in which the prepared precursor particles were diluted with argon. The temperature profile was raised to 620 ° C. at a constant rate of 10 ° C./min and held for 10 minutes.

The phosphor thus produced was analyzed in the same manner as in Example 1. As a result, Sr _0.9 Ca _0.1 Ga ₂ S ₄ crystal was slightly formed, but the main component was Sr _0.9 Ca _0.1 Ga ₂ O ₄ crystal. It turned out that it was not a desired structure. In the particle size distribution measurement by DLS, the particle size was 247 nm and the polydispersity index was as wide as 0.53.
The fluorescence characteristics of this powder were evaluated in the same manner as in Example 1. However, the relative value with the luminance of the phosphor of Example 1 as 100 was as low as 15. From this, it was confirmed that the temperature profile in hydrogen sulfide needs to be performed in two stages.

[Reference Example 1]
As a reference example, a SrGa ₂ S ₄ : Eu phosphor was produced. As raw materials, strontium carbonate powder (SrCO ₃ ), gallium oxide powder (Ga ₂ O ₃ ) and europium oxide powder (Eu ₂ O ₃ ) were used as SrCO ₃ : Ga ₂ O ₃ : Eu ₂ O ₃ ≈4.27: 5. The same procedure as in Example 1 was used except that the mass ratio was 54: 0.10. The D50 of the raw material particles was 7.3 μm, and the particle size of the precursor particles was approximately 20 nm and was amorphous. The phosphor thus prepared was analyzed in the same manner as in Example 1. As a result, the particle size was 112 nm and the polydispersity index was 0.39. Further, it is a single phase of SrGa ₂ S ₄ crystal, and the surface layer of the particle of about 4 nm has an amorphous structure, but other than that is a crystalline phase. Further, elements other than the constituent elements were below the detection limit. The phosphor of this example was green fluorescence having light absorption in a wide wavelength range from ultraviolet to blue and having a peak wavelength at 532 nm.

[Reference Example 2]
As a reference example, a CaGa ₂ S ₄ : Eu phosphor was produced by the production method of the present invention. As raw materials, calcium carbonate powder (CaCO ₃ ), gallium oxide powder (Ga ₂ O ₃ ) and europium oxide powder (Eu ₂ O ₃ ) were used as CaCO ₃ : Ga ₂ O ₃ : Eu ₂ O ₃ ≈2.90: 5. The same procedure as in Example 1 was used except that the mass ratio was 54: 0.10. The D50 of the raw material particles was 7.5 μm, and the particle size of the precursor particles was approximately 20 nm and was amorphous. The phosphor thus produced was analyzed in the same manner as in Example 1. As a result, the particle size was 115 nm and the polydispersity index was 0.40. Further, it is a single phase of CaGa ₂ S ₄ crystal, and the surface layer of the particle about 4 nm has an amorphous structure, but other than that is a crystalline phase. Further, elements other than the constituent elements were below the detection limit. The phosphor of this example was yellow-green fluorescence having a wide light absorption from ultraviolet to green and having a peak wavelength at 555 nm.

  Compositions of Examples 1 to 22, Comparative Example 1, Reference Examples 1 and 2, temperature conditions in phosphor step (c), particle size (D50), polydispersity index (PDI), relative luminance, amorphous Table 1 shows the quality thickness (average), and Table 2 shows the emission peak wavelength.

  Comparing Example 3 with Examples 7 to 11, it can be seen that even if the composition is the same, setting the second temperature higher increases the particle size and the emission luminance. Further, when Examples 1 to 6 and Examples 12 to 17 are compared, even if the first temperature and the second temperature are the same, the polydispersion can be achieved by slowing the temperature increase rate with time. It can be seen that the index is greatly reduced. Furthermore, from Examples 7 to 11 and Examples 18 to 22, the higher the second temperature, the larger the phosphor particle size. By setting the second temperature to 700 ° C. or less, the particle size is 250 nm. It turns out that it can control to less than.

  In Examples 1 to 22, impurities were not substantially detected by using an oxide as a raw material for Eu as an activator.

Example 23
A wavelength conversion film was produced, and a solar cell module having the configuration of FIG. 1A was produced using the wavelength conversion film.
100 g of ethylene-vinyl acetate resin as transparent resin material, 1.3 g of peroxide thermal radical initiator, 2.0 g of crosslinking agent, 0.5 g of silane coupling agent, and 3.0 g of the phosphor of Example 1 The mixture containing was kneaded with a roll mixer to prepare a resin composition. Next, about 30 g of the phosphor-containing transparent resin composition obtained above is sandwiched between release sheets, and a 0.6 mm thick stainless steel spacer is used, and a hot plate is adjusted to 90 ° C., and then molded into a sheet shape. Thus, a wavelength conversion film was obtained.

Next, the PET film was used as the substrate 8, and the sheet-like sealing material 6, the solar battery cell 7, the wavelength conversion film 1, and the front glass 5 were placed thereon in order and sealed with a vacuum laminator. The solar cell module thus produced was placed under simulated sunlight, and the short-circuit current density Jsc was measured according to JIS-C8914. As a result, it was 36.6 mA / cm ² .

Example 24
A solar cell module was produced in the same manner as in Example 23 except that the phosphor of Example 3 was used. When the short-circuit current density Jsc of the obtained solar cell module was measured in the same manner as in Example 23 and the current-voltage characteristics were evaluated, it was 36.9 mA / cm ² .

Example 25
A solar cell module was produced in the same manner as in Example 23 except that the phosphor of Example 8 was used. It was 36.8 mA / cm < ² > when the short circuit current density Jsc of the obtained solar cell module was measured like Example 23. FIG. The current-voltage characteristics were better than in Example 24 where the composition of the phosphor contained in the wavelength conversion film was the same, because the phosphor particle size was larger than in Example 24 and the phosphor brightness was higher. This is considered to be because the light is less scattered by the phosphor.

Example 26
A solar cell module was produced in the same manner as in Example 23 except that the phosphor of Example 19 was used. It was 37.1 mA / cm < ² > when the short circuit current density Jsc of the obtained solar cell module was measured like Example 23. FIG. The reason why the current-voltage characteristic was better than that of Example 25 in which the composition of the phosphor contained in the wavelength conversion film was the same is considered to be because the PDI of the phosphor is small and the scattering of light by the phosphor is small.

[Comparative Example 2]
A solar cell module was produced in the same manner as in Example 23 except that the wavelength conversion film was not used. The short-circuit current density Jsc of the solar cell module obtained in the same manner as in Example 23 was 35.9 mA / cm ² . Therefore, it turned out that the current-voltage characteristic of a solar cell module improves by using the fluorescent substance of this invention.

Example 27
Using the phosphor of Example 6, a white LED having the configuration of FIG. The LED chip 10 having a peak wavelength of 455 nm was mounted on the base 11 plate on which the electrical wiring 12 was formed, and the frame member 13 was formed in the periphery. Subsequently, the phosphor of Example 6 was mixed in the silicone resin and sufficiently stirred until it was uniformly dispersed. The mixing amount was adjusted so that the chromaticity coordinates were (x = 0.27 to 0.35, y = 0.27 to 0.35). Subsequently, this phosphor-dispersed resin was poured into a frame material and heated at 140 ° C. to cure the resin, thereby producing a white LED of this example. When a current of 20 mA was passed through the white LED, white light could be obtained. When the luminous efficiency was measured with MCPD manufactured by Otsuka Electronics, it was 60 lm / W.

Example 28
A white LED was produced in the same manner as in Example 27 except that the phosphor of Example 17 was used. White current could be obtained by passing a current of 20 mA, and the luminous efficiency was measured in the same manner as in Example 27. As a result, it was 63 lm / W. The luminous efficiency was higher than that of Example 27 having the same composition of the phosphor used, although the particle size of the phosphor was smaller than that of Example 27, but the PDI was significantly small and light scattering by the phosphor was in Example 27. It is thought that it is because it is less.

  1: wavelength conversion film, 3: phosphor particles

Claims (16)

A particulate phosphor containing a base material of a thiogallate sulfide represented by the following general formula (1) and an activator,
A phosphor having a particle size of 1000 nm or less and a volume ratio of a crystal phase in the particle represented by the following general formula (2).
_{Sr x Ca 1-x Ga 2} S 4 ( where, 0 <x <1) ( 1)
Vc / Vt ≧ (R−10) ³ / R ³ (2)
(In the above formula (2), Vc is the volume of the crystal phase in the particle, Vt is the volume of the particle, and R is the particle size)   The phosphor according to claim 1, wherein the particle size is less than 250 nm or greater than 250 nm and 500 nm or less.   The phosphor according to claim 1 or 2, wherein the particle size is 50 nm or more and less than 250 nm.   The phosphor according to any one of claims 1 to 3, wherein the activator is Eu.   The phosphor according to any one of claims 1 to 4, wherein a polydispersity index indicating a breadth of a particle size distribution is 0.5 or less.   The phosphor according to any one of claims 1 to 4, wherein a polydispersity index indicating a breadth of a particle size distribution is 0.3 or less.   The phosphor according to any one of claims 1 to 6, wherein the amount of impurities other than the constituent elements is 200 ppm or less. It is a manufacturing method of the fluorescent substance according to any one of claims 1 to 7,
(A) producing raw material particles containing a constituent component of the base material excluding a sulfur component and a constituent component of the activator at a composition ratio in the phosphor;
(B) A step of producing amorphous precursor particles by heating and cooling the raw material particles with thermal plasma;
(C) firing the precursor particles at a first temperature not lower than the crystallization temperature and higher than the crystallization temperature in a sulfur atmosphere, and then baking at a second temperature not lower than the crystallization temperature;
A method for producing a phosphor, comprising:   9. The phosphor according to claim 8, wherein in the step (c), the first temperature is 450 ° C. or more and 530 ° C. or less, and the second temperature is 550 ° C. or more and 1000 ° C. or less. Production method.   The method for producing a phosphor according to claim 9, wherein, in the step (c), the second temperature is 550 ° C or higher and 700 ° C or lower.   The method of manufacturing a phosphor according to any one of claims 8 to 10, wherein in the step (c), the first and second temperatures are controlled while monitoring an actual temperature of the phosphor. .   In the step (c), in each of the temperature raising process to reach the first temperature and the temperature raising process from the first temperature to the second temperature, the temperature rising rate becomes slower with time. The method for producing a phosphor according to any one of claims 8 to 11, wherein the phosphor is produced.   The method for producing a phosphor according to any one of claims 8 to 12, wherein in the step (a), the raw material particles are produced using an oxide as a constituent component of the activator.   A wavelength conversion film, wherein the phosphor according to any one of claims 1 to 7 is dispersed in the film.   A solar cell module using the phosphor according to any one of claims 1 to 7.   A light-emitting device using the phosphor according to claim 1.

Images