KR101243773B1 - Wavelength converting composition for light emitting device and sollar cell, light emitting device and sollar cell comprising the composition, preparing method for the composition - Google Patents

Abstract

The present invention is a wavelength conversion composition capable of absorbing light in the wavelength range of 250 to 500 nm and converting it into a long wavelength range of 600 to 850 nm, and is not only suitable for use as a phosphor for tuning a white color light emitting diode, but also The present invention relates to a wavelength conversion composition that can be used as an energy down-converting material that can improve the conversion efficiency of a solar cell by converting short wavelength light of 250 to 500 nm included in light into a near wavelength of 900 nm, and a method of manufacturing the same.
The wavelength conversion composition according to the present invention is represented by the following formula (1), containing 5% by volume or less of AlN, when excited with light of 400nm wavelength, the peak wavelength of the emission spectrum according to the concentration of the europium ion activator is 620nm ~ A wavelength conversion composition, characterized by a change in the 710 nm range.
[Formula 1]
Mg _{1 - z} Al _x Si _y N _δ : Eu _z ^{2 +}
Where 0.1≤x≤2, 0.1≤y≤2, 0.0001≤z≤0.2, 0.9≤δ≤5.33

Description

WAVELENGTH CONVERTING COMPOSITION FOR LIGHT EMITTING DEVICE AND SOLLAR CELL, LIGHT EMITTING DEVICE AND SOLLAR CELL COMPRISING THE COMPOSITION, PREPARING METHOD FOR THE COMPOSITION}

The present invention relates to a wavelength conversion composition made of nitride and a method for manufacturing the same. More particularly, the present invention relates to a wavelength conversion composition capable of absorbing light in the wavelength range of 250 to 500 nm and converting it into a long wavelength range of 600 to 850 nm. It is possible to emit light in a wide range up to and is not only suitable for use as a fluorescent color for white color light-emitting diode tuning phosphor, but also when applied to solar cells with excellent conversion efficiency in the wavelength range of about 900 nm, it is included in the sunlight. The present invention relates to a wavelength conversion composition capable of improving the conversion efficiency of a solar cell by converting a short wavelength light of 500 nm into a near wavelength of 900 nm and a method of manufacturing the same.

BACKGROUND OF THE INVENTION In recent years, white LED light emitting devices, which have been spotlighted for lighting, LCD backlights, automobile lighting, and the like, usually include LED light emitting elements emitting blue or near ultraviolet rays, and phosphors that convert wavelengths using light emitted from the light emitting elements as excitation sources. It is made, including.

As a representative method for implementing such a white LED, conventionally, a blue light emitting diode using an InGaN-based material as a light emitting device is used, and as a phosphor, a yellow light emission represented by a composition formula of (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ is used. A typical YAG-based phosphor is used. The white LED emits blue light emitted from the light emitting element into the phosphor layer and repeats absorption and scattering several times in the phosphor layer. In this process, the blue light absorbed by the phosphor is converted into yellow. This is done by mixing a portion of the wavelength-converted yellow light and the incident blue light to appear white to the human eye. However, this white LED has a problem in that only light having a low red component, high color temperature, and low color rendering of the red light is obtained.

By the way, in the display lighting of a store, the lighting for a medical field, etc., a slightly reddish-light white light-emitting device is calculated | required, and even for general lighting, the white LED which is close to the light bulb color mild to human eyes is strong At present, two or more phosphors are used to improve color reproducibility and color rendering (index indicating the degree of light source being close to sunlight).

Among the phosphors, conventionally, oxide-based phosphors excellent in stability represented by YAG phosphors have been mainly used. However, there is a limit to the warm color white light emission only with the oxide-based phosphor, the sulfide-based phosphor is excellent in the light emission characteristics, but the stability is difficult to actually use.

On the other hand, in the case of nitride-based fluorescent material, and this light emission band of the Eu ^{2 +} ions in the nitride matrix is compared to the oxide due to covalent bond between Eu ^{2 +} ions and N ligands move significantly toward the long wavelength. In addition, the nitride fluorescent material activated with Eu ^{2 +} ions is higher quantum efficiency, the light stability and thermal stability shows excellent properties, Eu ^{2 +} ions to produce a white light emitting device using a two or three phosphors Therefore, it is reported that it can be applied to various white LEDs because it shows an appropriate band shape.

Representative examples of these nitride-based fluorescent material is CaAlSiN _3: and the like ^{Eu 2 +: Eu 2 + (} Sr, Ca) AlSiN 3: Eu 2 + or Sr ₂ Si ₅ N _8. Although CaAlSiN ₃ : Eu ^{2 +} phosphors are spotlighted as representative red light emitting phosphors, phosphors capable of emitting light in various wavelengths are required to realize various warm color-based white light emission.

On the other hand, the MgAlSiN ₃ : Eu ^{2 +} phosphor has a similar structure and spectral characteristics compared to CaAlSiN ₃ : Eu ^{2 +} , which is a representative red phosphor, and has been considered as a candidate to replace CaAlSiN ₃ : Eu ^{2 +} phosphor. In fact, the synthesis of MgAlSiN ₃ : Eu ^{2 +} phosphors has not been studied because the synthesis is not easy compared to CaAlSiN ₃ : Eu ²⁺ phosphors.

There are many limitations in the manufacture of nitride phosphors. Basically, starting materials should be metal nitrides, and the raw materials should be reacted in a synthesis furnace at a reaction temperature of up to 2,000 ° C under nitrogen atmosphere of several tens of atmospheres to obtain nitride phosphors. Because it can. However, MgAlSiN _3: In the process of synthesizing the Eu ^{2 +} phosphor, CaAlSiN _3: Eu ^{2 +,} unlike the fluorescent material, a lot of residues, such as the raw material AlN or beta Im-alone (β-SiAlON) remains synthesizing phosphors of the complete single-phase Difficult to do

On the other hand, in the case of solar cells, the conversion efficiency for converting the energy of incident sunlight into electrical energy must be high. The conversion efficiency is affected by various factors such as light reflectivity of the solar cell, absorption efficiency of a specific wavelength band, and internal resistance of the battery. Currently, the cell efficiency of silicon solar cells is known to be about 10 to 19%.

In the case of the silicon solar cell, the conversion efficiency is known to be the best in the near infrared region of about 900nm range, and the sunlight includes light of various wavelengths such as X-rays, ultraviolet rays, visible rays, and infrared rays. Therefore, if the light having low conversion efficiency among the light incident on the silicon solar cell can be converted into light having a long wavelength near 900 nm, the conversion efficiency of the solar cell can be increased.

The present invention is to realize the above-described problems of the prior art and the implementation of various emission colors required in white LEDs, by adjusting the concentration of the activator, a broad wavelength band from orange (600 nm) to the infrared region (750 nm) It is an object of the present invention to provide a nitride-based wavelength conversion composition that can be used as a phosphor capable of emitting light to enable various white tunings.

In addition, another object of the present invention is to convert the light of 250 ~ 500nm contained in sunlight into long wavelength light of 600 ~ 850nm, nitride-based wavelength conversion composition that can significantly increase the conversion efficiency when applied to solar cells To provide.

In addition, another object of the present invention is to provide a method for producing the nitride-based wavelength conversion composition.

As a means for solving the above problems, the present invention, represented by the following formula (1), containing 5% by volume or less of AlN, when excited with light of 400nm wavelength, the peak wavelength of the emission spectrum according to the concentration of europium is 620nm It provides a wavelength conversion composition characterized by varying in the range ~ ~ 710nm.

[Formula 1]

Mg _1-z Al _x Si _y N _d : Eu _z ²⁺

Here, x is 0.1 to 2, preferably 0.5 to 1.5, y is 0.1 to 2, preferably 0.5 to 1.5, z is 0.00001 to 0.2, preferably 0.0001 to 0.015, d is 0.9 to 5.33, Preferably it is 2.5-3.5.

In the wavelength conversion composition, AlN is preferably 5% by volume or less, but more preferably 3% by volume or less.

In addition, the wavelength conversion composition is characterized in that consisting of a single phase in which little residue such as AlN.

In addition, the wavelength conversion composition may be used as a phosphor of the light emitting device, and since the peak wavelength of the emission spectrum is in the range of 620 nm to 710 nm, it is possible to emit light in a range from orange to near infrared rays, which is suitable for realizing a warm white light emission. Can be.

In addition, the present invention includes a light emitting device such as a white LED including the wavelength conversion composition.

In addition, in order to achieve another object of the present invention, the present invention, represented by the following formula (2), containing 5% by volume or less of AlN, absorbs light in the wavelength range of 250nm to 500nm, light in the wavelength range of 600nm to 850nm It provides a wavelength conversion composition for solar cells to convert to.

[Formula 2]

Mg _{1 - z} Al _x Si _y N _d : Eu _z ^{2 +}

Here, x is 0.1 to 2, preferably 0.5 to 1.0, y is 0.1 to 2, preferably 0.5 to 1.5, z is 0.00001 to 0.2, preferably 0.015 to 0.2, d is 0.9 to 5.33, Preferably it is 2.5-3.5.

In the solar cell wavelength conversion composition, AlN is more preferably 5% by volume or less and 3% by volume or less.

In addition, the present invention provides a solar cell comprising the wavelength conversion composition for the solar cell, the solar cell can be used in various kinds of solar cells, silicon solar cells are the most preferred example.

In addition, the present invention to solve the other object, a method for producing the wavelength conversion composition, comprising the steps of: (a) weighing the raw material powder of the wavelength conversion composition; (b) preparing a mixture by dry mixing the weighed raw powder in an atmosphere in which oxygen and water contents are maintained at 1 ppm or less; And (c) calcining the mixture at a temperature of 1300 to 2000 ° C. and a nitrogen atmosphere of 5 to 20 atmospheres to produce a fired product.

In the above production method, the nitrogen atmosphere is characterized in that it contains 80% or more nitrogen.

In addition, in the above production method, the raw material powder is characterized in that it comprises Mg ₃ N powder, AlN powder, a-Si ₃ N ₄ powder, EuN powder.

In the above production method, the raw material powder is weighed non-stoichiometrically. This is because the stoichiometry of the raw material powder itself is not constant. Because it is difficult to obtain.

The wavelength conversion composition according to the present invention is capable of emitting light from orange to near infrared rays because the peak wavelength of the emission spectrum is in the range of 620 nm to 710 nm, and can be suitably used as a tuning phosphor for implementing white light emission of various colors.

In addition, the wavelength conversion composition according to the present invention can absorb the short wavelength light of 250 ~ 500nm included in the sunlight, can be converted to a long wavelength of 600 ~ 850nm, when applied to solar cells, it can contribute to increase the conversion efficiency have.

Figure 1 shows the XRD pattern of the MgAlSiN ₃ : Eu ^{2 +} phosphor prepared according to the present invention.
Figure 2 shows the change in the emission spectrum according to the concentration of Eu ^{2 +} when excited by 400nm excitation light.
3 is a result of measuring the excitation spectrum when the concentration of Eu ^{2 +} ion in the MgAlSiN ₃ : Eu ^{2 +} phosphor prepared according to the embodiment of the present invention was 0.005 mol and 0.05 mol, respectively.

Hereinafter, the wavelength conversion composition according to the present invention will be described in detail based on the preferred embodiment of the present invention.

The wavelength conversion composition (henceforth a "phosphor") which concerns on this embodiment can be manufactured, for example by the manufacturing method demonstrated below.

First, magnesium nitride (Mg ₃ N ₂ , Aldrich, 99.5%), silicon nitride (α-Si ₃ N ₄ , Aldrich), and aluminum nitride (AlN, Aldrich, 98%) are prepared as raw materials for forming the phosphor matrix. . In addition, europium nitride (EuN, high purity, 99.9%) is prepared as an activator for light emission.

Subsequently, using the raw material prepared as described above, the raw material was weighed to obtain a MgAlSiN ₃ : Eu ²⁺ phosphor containing minimal AlN and consisting of a single phase. In the embodiment of the present invention, a non-stoichiometric method was used in the weighing of the raw material without using the stoichiometric method considering the composition of the raw material. This is because magnesium nitride, silicon nitride, aluminum nitride, and the like all contain oxides having a certain amount of impurity, and accurate stoichiometric data are not reported. Accordingly, in the present invention, in order to obtain Mg _1-z Al _x Si _y N _d : Eu _z ²⁺ phosphor, x and y are each weighed so as to have a ratio of 0.5 to 1.5, and z is 0.0001 to It was weighed out to a ratio of 0.070.

The raw materials weighed in this way were mixed by hand for 10 minutes in an atmosphere of oxygen and water content of 1 ppm or less to obtain a mixture.

The mixture thus obtained is fired in a pressurized atmosphere. The pressurized atmosphere is carried out in an atmosphere consisting mainly of nitrogen gas of 5 atm or more and 20 atm or less. When firing in a high pressure nitrogen gas atmosphere, decomposition of nitride synthesized during high temperature firing can be prevented or suppressed. The compositional deviation of the resulting nitride can be reduced, thereby making it possible to produce a phosphor composition having excellent performance. On the other hand, having nitrogen gas as a main component means that nitrogen gas is contained in an amount of 80% or more relative to the total gas. In addition, a reducing atmosphere is preferred in order to generate a lot of resurrection Jane Eu ^{2 +} ions.

In addition, the firing temperature is preferably 1300 ~ 2000 ℃, more preferably 1600 ℃ or more in order to obtain a high quality phosphor. In addition, the firing time can be in the range of 30 minutes to 100 hours, but considering the quality and productivity, 2 hours to 8 hours is preferable. In an embodiment of the present invention, a phosphor was prepared by firing at a firing temperature of 1800 ° C. for 2 hours in a nitrogen-hydrogen mixed gas (nitrogen 97% + hydrogen 3%) at 10 atmospheres. The wavelength conversion composition thus prepared may be one having an atomic ratio of the above-described composition, and may include a composition in which some silicon or aluminum is oxidized and modified to SiO ₂ or A1 ₂ O ₃ .

As a result of XRD diffraction analysis of the composition obtained as described above, in the Mg _{1 - z} Al _x Si _y N _d : Eu _z ^{2 +} phosphor, the ratio of x / y during initial material weighing was maintained in the range of 0.67 to 1.33. It was found that a single-phase MgAlSiN ₃ : Eu ^{2 +} phosphor containing almost no AlN and having a stoichiometric exact match could be obtained.

Figure 1 shows the XRD diffraction analysis of the MgAlSiN ₃ : Eu ^{2 +} phosphor prepared in accordance with an embodiment of the present invention. As shown in FIG. 1, it can be seen that when the x / y ratio is maintained at 0.67 to 1.33, a stoichiometrically accurate MgAlSiN ₃ : Eu ²⁺ phosphor is obtained. At this time, the volume fraction of AlN was measured to 3% or less.

Figure 2 shows a change at the time when a different doping concentration of Eu ^{2 +} ions, and an emission spectrum (400nm here). As will be confirmed from FIG. 2, it can be seen that movement in red in a wide range with increasing the concentration of Eu ^{2 +} ions, and the peak wavelength of from 620nm to 710nm.

In particular, Eu ^{2 +,} when the ion concentration to increase moles 0.017 at 0.013 mole, to the peak wave length change abruptly over 700nm below 640nm (i.e., the peak wavelength to a sudden change in boundary 0.015 mol), which MgAlSiN ₃ Eu ^{2 +} ions of two different exemplary local structure around within the structure (local structure) or local structural group (local structure group) is present means that each structure can represent a peak wavelength of less than 640nm, and the peak wavelength over 700nm have.

3 is a result of the concentration of Eu ^{2 +} ion measuring the excitation spectrum of 0.005 mol and 0.05 mol, respectively when. As can be seen in FIG. 3, the excitation behavior in the two samples shows a clear difference, especially in the wavelength region longer than 450 nm. Such a difference in the excitation spectrum makes it possible to estimate the difference between local structure around Eu ^{2 +} ions.

Thus, MgAlSiN ₃ according to the invention: Eu ^{2 +} phosphor is not more than the peak wavelength of 640nm from a practical point of view there may be suitably used in the fluorescent substance as a white LED, Eu ^{2 +} ion concentration is preferably 0.02 mol more than 0.015 mol In the above case, the light emission wavelength is out of the visible region, and in this case, the light emission wavelength may be suitably used as an energy down-converting material for increasing the conversion efficiency of the solar cell.

Claims (14)

delete delete delete delete delete delete It is represented by the following formula (2), containing 5% by volume or less of AlN, absorbs light in the wavelength range of 250nm to 500nm, converts to light in the wavelength range of 600nm to 850nm, characterized in that the peak wavelength is 660nm to 710nm Wavelength conversion composition for solar cell.
(2)
Mg _1-z Al _x Si _y N _d : Eu _z ²⁺
Where 0.1≤x≤2, 0.1≤y≤2, 0.0001≤z≤0.2, 0.9≤d≤5.33 The method of claim 7, wherein
The AlN wavelength conversion composition for a solar cell, characterized in that less than 3% by volume. The method of claim 7, wherein
z is a wavelength conversion composition for solar cells, characterized in that 0.015 ~ 0.2. The solar cell containing the wavelength conversion composition in any one of Claims 7-9. A method for producing a wavelength converting composition according to any one of claims 7 to 9,
(a) weighing raw material powder of the wavelength conversion composition;
(b) preparing a mixture by dry mixing the weighed raw powder in an atmosphere in which oxygen and water contents are maintained at 1 ppm or less; And
(c) calcining the mixture at a temperature of 1300 to 2000 ° C. and a nitrogen atmosphere of 5 to 20 atmospheres to produce a fired product.
The raw material powder, Mg ₃ N powder, AlN powder, α-Si ₃ N ₄ powder, EuN powder manufacturing method of the wavelength conversion composition characterized in that it comprises. The method of claim 11,
The nitrogen atmosphere is a method for producing a wavelength conversion composition comprising at least 80% nitrogen. delete The method of claim 11,
Weighing the raw material powder is a non-stoichiometric method for producing a wavelength conversion composition.

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