JP4188350B2 - Semiconductor diode and display device using the same - Google Patents

Description

  The present invention relates to a semiconductor diode and a display device using the semiconductor diode, and more particularly to a semiconductor diode capable of efficiently absorbing ultraviolet excitation light having a wavelength of around 370 nm and converting it into red light, and a high luminance display using the semiconductor diode. Relates to the device.

  A light emitting diode (LED) is a semiconductor diode that emits light, and converts electrical energy into visible light or infrared light. In particular, in order to use visible light, it is widely used as an LED lamp in which a light emitting chip formed of a light emitting material such as GaP, GaAsP, or GaAlAs is sealed with a transparent resin or the like. In addition, a display-type LED lamp in which a light emitting material is fixed to the upper surface of a printed board or a metal lead and sealed with a resin case shaped like a number or letter is also frequently used.

  In addition, it is possible to appropriately adjust the color of the emitted light by including various phosphor powders on the surface of the light emitting chip or the resin of the light emitting diode. That is, the emission color of the light-emitting diode lamp can reproduce light emission in the visible light region according to each usage from blue to red. Further, since the light emitting diode is a semiconductor element, it has a long life and high reliability, and when used as a light source, its replacement work is also reduced, so that a portable communication device, a personal computer peripheral device, an OA device, It is widely used as a component of various display devices such as household electrical equipment, audio equipment, various switches, and light source display plates for backlights.

  Recently, however, the color sense of the users of the various display devices has been further improved, and various display devices are required to have a function capable of reproducing subtle hues with higher definition. There is also a strong demand for a function of reproducing white or various intermediate colors with a single light emitting diode.

  Therefore, by applying blue, red and green light emitting phosphors on the surface of the light emitting chip of the LED lamp, or by incorporating the above various phosphor powders in the resin constituting the light emitting diode, the light emitting diode can be made from one light emitting diode. Attempts have also been made to extract white or any intermediate color. Conventionally, there are many blue-emitting phosphors and green-emitting phosphors that efficiently emit visible light by ultraviolet rays having a wavelength of around 370 nm emitted from light-emitting diodes.

  However, in particular, the red light emitting phosphor has a problem that it is weakly absorbed with respect to excitation light (ultraviolet light) having a wavelength of around 370 nm as compared with other blue and green light emitting phosphors. When trying to reproduce the radiated light, there is a problem that the luminance of the emitted light is greatly reduced.

  The present invention has been made to solve the above problems, and can absorb red light efficiently and emit red light efficiently at around 370 nm, which is the excitation wavelength of the light emitting chip, from one light emitting chip. An object of the present invention is to provide a semiconductor diode containing a red light-emitting phosphor that can be used practically for extracting white or any intermediate color, and a high-luminance display device using the semiconductor diode.

  In order to achieve the above-mentioned object, the present inventors prepared red light-emitting phosphors having various compositions, and experimentally examined the effects of the types and addition amounts of the composition components on the excitation spectrum distribution and emission luminance of the phosphors. A comparative study was conducted.

  As a result, by adding a predetermined amount of samarium (Sm) to the europium activated lanthanum oxysulfide phosphor, the peak of the excitation spectrum distribution can be shifted to the long wavelength side of around 370 nm, and the excitation ultraviolet light of the light emitting chip of the semiconductor diode As a result, it has been found that a red light emitting phosphor capable of efficiently emitting red light emission can be obtained for the first time. The present invention has been completed based on the above findings.

That is, the semiconductor diode according to the present invention have the general formula _{(La 1-x-y Eu} x Sm y) 2 O 2 S ( where, 0.01 ≦ x ≦ 0.15,0.0001 ≦ y ≦ 0.03) A red light emitting phosphor composed of a europium samarium activated lanthanum oxysulfide phosphor represented by the above , and a blue light emitting phosphor and a green light emitting phosphor are combined to emit light in any white color or any intermediate color. To do.

Further, other semiconductor diode according to the present invention have the general formula _{(La 1-x-y Eu} x Sm y) 2 O 2 S ( where, 0.01 ≦ x ≦ 0.15,0.0001 ≦ y ≦ 0 0.03), a semiconductor diode having a red light emitting phosphor made of a europium / samarium activated lanthanum oxysulfide phosphor and a light emitting chip, wherein the light emitting chip emits ultraviolet light.

  In the semiconductor diode, the peak wavelength in the excitation spectrum distribution is preferably in the ultraviolet long wavelength region. Furthermore, it is preferable that the peak wavelength in the excitation spectrum distribution exists in the ultraviolet wavelength region of 330 to 430 nm.

  Furthermore, it is more preferable that the atomic ratio (x) of europium (Eu) in the general formula is in the range of 0.03 to 0.08. Moreover, it is more preferable that the atomic ratio (y) of samarium (Sm) in the general formula is in the range of 0.001 to 0.01.

  Furthermore, 30 mol% or less of La may be substituted with at least one element of Y and Gd. Moreover, it is more preferable that the substitution amount of at least one of Y and Gd with respect to La is 5 to 20 mol%.

  In the semiconductor diode including the phosphor and the light emitting chip, the phosphor is preferably contained in a resin layer.

  Furthermore, the display device according to the present invention is formed using the semiconductor diode configured as described above.

Furthermore, the manufacturing method of the red light-emitting phosphors used in the semiconductor diode according to the present invention have the general formula _{(La 1-x-y Eu} x Sm y) 2 O 2 S ( where, 0.01 ≦ x ≦ 0. 15, 0.0001 ≦ y ≦ 0.03), a step of uniformly blending the raw material powders to prepare a raw material mixture, a step of firing the obtained raw material mixture, The obtained fired product is washed with pure water to remove unnecessary soluble components, the step of acid-washing the fired product in an acidic liquid having a pH of 2 or higher, and the acid-washed fired product to pure water. And a step of filtering and drying after washing.

Furthermore, the semiconductor diode according to the present invention is a semiconductor diode that converts electrical energy into visible light or infrared light by energizing the light emitting chip combined with the light emitting material, and the light emitting material combined with the light emitting chip is generally used. formula _{(La 1-x-y Eu} x Sm y) 2 O 2 S ( where, 0.01 ≦ x ≦ 0.15,0.0001 ≦ y ≦ 0.03) europium-samarium Katsusan sulfide represented by It is a lanthanum phosphor.

  Here, Eu (europium) acts as an activator (activator) that enhances the luminous efficiency of the phosphor, and is added at an atomic ratio x of 0.01 to 0.15 with respect to La (lanthanum). The When the addition ratio is less than 0.01, the luminance is remarkably lowered and the effect of improving the luminous efficiency is small. On the other hand, when the addition ratio exceeds 0.15, coloring is likely to occur, and the luminance is remarkably lowered due to concentration quenching, which hinders the luminous efficiency of the phosphor. The atomic ratio x of Eu is more preferably in the range of 0.03 to 0.08.

  In addition to acting as an activator, Sm (samarium) has the effect of shifting the excitation spectrum wavelength of the phosphor to the longer wavelength side, and is 0.0001 to 0.03 relative to La (lanthanum). Added in proportions. When the addition ratio is less than 0.0001, the shift effect is insufficient. On the other hand, when the addition ratio exceeds 0.03, the luminous efficiency of the phosphor is similarly inhibited. A more preferable atomic ratio y of Sm is in the range of 0.001 to 0.01.

  The red light-emitting phosphor having the above composition range exists in the ultraviolet wavelength region where the peak wavelength in the excitation spectrum distribution is 360 to 380 nm, and efficiently emits red light by the ultraviolet light for excitation of the semiconductor diode.

  In addition, yttrium (Y) and gadolinium (Gd), which are partially substituted with La, have the effect of increasing the emission energy in the red region by being dissolved in the phosphor, and the amount of substitution with La is 30 mol% or less. This is because if the amount of substitution exceeds 30 mol%, the crystal distortion cannot be ignored and the light emission intensity becomes insufficient. A more preferable substitution amount is in the range of 5 to 20 mol%.

The red light emitting phosphor used in the semiconductor diode according to the present invention is manufactured through the following steps, for example. In other words, the general formula _{(La 1-x-y Eu} x Sm y) 2 O 2 S ( where, 0.01 ≦ x ≦ 0.15,0.0001 ≦ y ≦ 0.03) to have a composition represented by Each raw material powder such as La ₂ O 3, Eu ₂ O ₃ , Sm ₂ O ₃ , and S is uniformly mixed with a fluxing agent such as Na ₂ CO ₃ and Li ₃ PO _4, and then mixed thoroughly with a ball mill or the like. A step of preparing a mixture, a step of storing the obtained raw material mixture in a firing container such as an alumina crucible with a lid, and firing in the atmosphere at a temperature of 1100 to 1400 ° C. for 3 to 6 hours; Washing the fired product with pure water to remove unnecessary soluble components, further washing the fired product with acid in an acidic solution having a pH of 2 or higher, and washing the acid-washed fired product with pure water 3 It is manufactured through a step of filtration and drying after washing 5 times.

  Here, in the acid washing step of the above production method, in particular, by washing the phosphor particle dispersion while maintaining it in an acidic region having a pH of 2 or more, non-luminescent components mixed in the phosphor particles can be removed with high efficiency, The product yield of the phosphor particles can be increased to 90% or more, and a remarkable effect in practical use is exhibited. In order to increase both the removal effect of the non-luminescent component and the product yield, it is more preferable to maintain the pH during the acid cleaning in the range of 2 to 4.

Furthermore, the semiconductor diode according to the present invention is a semiconductor diode that converts electrical energy into visible light or infrared light by energizing the light emitting chip combined with the light emitting material, and the light emitting material combined with the light emitting chip is generally used. formula _{(La 1-x-y Eu} x Sm y) 2 O 2 S ( where, 0.01 ≦ x ≦ 0.15,0.0001 ≦ y ≦ 0.03) europium-samarium Katsusan sulfide represented by It is a lanthanum phosphor.

  The light emitting chip constituting the semiconductor diode is not particularly limited, but generally, a chip made of InGaN-based material, GaP-based material, GaAsP-based material, GaAlAs-based material or the like is used.

  According to the semiconductor diode, since the red light emitting phosphor having a high peak of the excitation spectrum is contained in the ultraviolet wavelength region serving as the excitation source, the emission luminance in the red region can be greatly increased.

  According to the semiconductor diode having the above configuration, since a predetermined amount of Sm is added to the red light emitting phosphor and the excitation spectrum wavelength is shifted to the excitation ultraviolet wavelength side of the semiconductor diode, the excitation ultraviolet light having a wavelength of around 370 nm is efficiently used. It can be absorbed and converted to red light, and the emission luminance in the red region can be greatly increased.

  In addition, by appropriately selecting a combination of a red light-emitting phosphor and other blue and green light-emitting phosphors, not only white light having an arbitrary color temperature but also intermediate colors such as purple, pink, and blue-green can be obtained. A semiconductor diode that can be taken out with high accuracy can be realized, and an excellent practical effect can be obtained.

  As described above, according to the semiconductor diode of the present invention, a predetermined amount of Sm is added to the red light-emitting phosphor to shift the excitation spectrum wavelength to the semiconductor diode excitation ultraviolet wavelength side. Can be efficiently absorbed and converted to red light, and the emission luminance in the red region can be greatly increased.

  In addition, by appropriately selecting a combination of a red light-emitting phosphor and other blue and green light-emitting phosphors, not only white light having an arbitrary color temperature but also intermediate colors such as purple, pink, and blue-green can be obtained. A semiconductor diode that can be taken out with high accuracy can be realized, and an excellent practical effect can be obtained.

  Next, embodiments of the present invention will be described more specifically based on the following examples.

[Example 1]
229.7 g of La ₂ O ₃ powder as a phosphor constituting raw material, 16.01 g of Eu ₂ O ₃ powder, 2.64 g of Sm ₂ O ₃ powder, 61.38 g of S powder, and as a flux The Na ₂ CO ₃ powder of 86.94 g and the Li ₃ PO ₄ powder of 24.84 g were accurately weighed and uniformly mixed using a ball mill to obtain a raw material mixture.

Next, the obtained raw material mixture was housed in an alumina crucible with a lid and baked at a temperature of 1250 ° C. for 4 hours. The obtained fired product was sufficiently washed with pure water to remove unnecessary soluble components. Thereafter, the fired product is finely pulverized with a ball mill to form phosphor particles, and further, acid washing is performed while adding sulfuric acid and nitric acid to maintain an acidic region having a pH value of 2.5, and then 4 times with pure water. Washed. The washed phosphor particles were filtered and dried to prepare a red light-emitting phosphor for Example 1 having a composition of (La _0.93 Eu _0.06 Sm _0.01 ) ₂ O ₂ S.

  The excitation spectrum distribution of the obtained red light emitting phosphor is shown in FIG. 1, while the emission spectrum distribution is shown in FIG. As is clear from FIG. 1, the phosphor for Example 1 emits red light with high efficiency by ultraviolet rays having a wavelength of 330 to 400 nm. As is clear from FIG. 2, the phosphor for Example 1 is a red light-emitting phosphor having a light emission peak in the vicinity of a wavelength of 625 nm when ultraviolet excitation at 380 nm is performed.

Furthermore, when the luminance of the red light emitting phosphor for Example 1 was measured using the conventional (Y _0.955 Eu _0.045 ) ₂ O ₂ S phosphor as a standard under excitation at 380 nm, it was as high as 180%. A value was obtained. Therefore, it was found that the excitation spectrum distribution of the phosphor for this example can efficiently convert the radiant energy of the semiconductor diode into red light.

[Example 2]
291.5 g of La ₂ O ₃ powder as a phosphor constituent raw material, 20.14 g of Eu ₂ O ₃ powder, 0.67 g of Sm ₂ O ₃ powder, 77.17 g of S powder, and as a flux 109.3 g of Na ₂ CO ₃ powder and 31.23 g of K ₃ PO ₄ powder were accurately weighed and uniformly mixed using a ball mill to obtain a raw material mixture.

Next, the obtained raw material mixture was accommodated in an alumina crucible with a lid and baked at a temperature of 1150 ° C. for 5 hours. The obtained fired product was sufficiently washed with pure water to remove unnecessary soluble components. Thereafter, the fired product is finely pulverized with a ball mill to form phosphor particles, and further, acid washing is performed while adding sulfuric acid and nitric acid to maintain an acidic region having a pH value of 2.5, and then 4 times with pure water. Washed. The washed phosphor particles were filtered and dried to prepare a red light emitting phosphor for Example 2 having a composition of (La _0.938 Eu _0.060 Sm _0.002 ) ₂ O ₂ S.

  When the luminance of the red light emitting phosphor for Example 2 was measured by the same method as in Example 1, a luminance as high as 185% was obtained. The excitation spectrum distribution and emission spectrum distribution of the phosphor for Example 2 were basically the same as those in Example 1. From the above results, it was found that the red light emitting phosphor for Example 2 can also efficiently convert the radiant energy of the light emitting diode (LED) into red light.

[Examples 3 to 11 and Comparative Examples 1 to 4]
Each phosphor raw material powder is weighed so that the phosphor composition finally becomes the composition shown in Table 1, and calcined, washed with pure water and pulverized under the same processing conditions as in Example 1, and then the pH values shown in Table 1 The red emission fluorescence for Examples 3 to 11 and Comparative Examples 1 to 4 is carried out by performing acid cleaning while maintaining the acidic region, and further performing pure water cleaning, filtration and drying under the same conditions as in Example 1. Each body was prepared.

  Comparative Example 1 uses a conventional europium-activated yttrium oxysulfide phosphor that does not contain Sm, Comparative Example 2 uses a phosphor that contains excessive Sm, and Comparative Example 3 has an excessively low Sm content. A certain phosphor is used, and Comparative Example 4 is an example using a phosphor containing an excessive amount of Gd.

The red light-emitting phosphors for the examples and comparative examples thus prepared were irradiated with excitation ultraviolet light having a wavelength of 380 nm, and the luminance was measured. In addition, the brightness | luminance of each fluorescent substance was shown relatively by making the brightness | luminance of the fluorescent substance for Comparative Example 1 into a reference value (100%). The measurement results are shown in Table 1 below.

  As is clear from the results shown in Table 1 above, the red light-emitting phosphor for each example to which a predetermined amount of Sm was added efficiently absorbs excitation light (ultraviolet light) having a wavelength of 380 nm and converts it into red light. As compared with the phosphors having the conventional compositions shown in Comparative Examples 1 to 4, it has been found that the emission luminance in the red region can be significantly increased.

  In addition, by appropriately combining the red light emitting phosphors for each example with other blue and green light emitting phosphors, not only white light having an arbitrary color temperature, but also purple, pink, blue green, etc. Intermediate colors can be extracted with high accuracy.

  Next, the influence of the pH condition on the product yield of the phosphor and the efficiency of removing impurities when the phosphor particles are acid-washed will be described based on Example 12 below.

[Example 12]
In the method for producing a red light-emitting phosphor for Example 1, the pH value of the dispersion in the step of washing the phosphor particles with an acid is as shown in Table 2, with strong acid region (<pH 0.8), pH 1, pH 2, The product yield of phosphor particles and the removal effect of non-luminescent components were measured when acid cleaning was carried out while maintaining pH 4 and pH 6, and the results shown in Table 2 below were obtained.

  As is clear from the results shown in Table 2 above, when acid cleaning is performed under acidic conditions in a strong acid region and pH 1, the removal effect by elution of non-luminescent components is high, but the elution amount of the phosphor particles themselves is also high. The product yield increased to a low value of 60-70%. On the other hand, even if the acid cleaning was performed in the weakly acidic region at pH 6, almost no effect of removing the non-luminescent component was obtained.

  When acid cleaning was performed at pH 2 to 4, both the non-luminescent component removal effect and the product yield were appropriate. Accordingly, it has been found that maintaining the pH value during acid cleaning in an acidic region of 2 or more is very preferable in practice in order to optimize the purity and manufacturing cost of the phosphor.

The graph which shows the excitation spectrum distribution of one Example of the red light emission fluorescent substance used with the semiconductor diode which concerns on this invention. The graph which shows the emission spectrum distribution of one Example of the red light emission fluorescent substance used with the semiconductor diode which concerns on this invention.

Claims (10)

Europium / samarium-activated acid represented by the general formula (La _1-xy Eu _x Sm _y ) ₂ O ₂ S (where 0.01 ≦ x ≦ 0.15, 0.0001 ≦ y ≦ 0.03) A semiconductor diode characterized in that a red light-emitting phosphor made of a lanthanum sulfide phosphor is combined with a blue light-emitting phosphor and a green light-emitting phosphor to emit light in white or any intermediate color at any color temperature . Europium / samarium-activated acid represented by the general formula (La _1-xy Eu _x Sm _y ) ₂ O ₂ S (where 0.01 ≦ x ≦ 0.15, 0.0001 ≦ y ≦ 0.03) A semiconductor diode having a red light emitting phosphor made of lanthanum sulfide phosphor and a light emitting chip, wherein the light emitting chip emits ultraviolet light. 3. The semiconductor diode according to claim 1, wherein a peak wavelength in the excitation spectrum distribution is present in an ultraviolet long wavelength region. Peak wavelength in an excitation spectrum distribution, semiconductor diode according to any one of claims 1 to 3, characterized in that present in the ultraviolet wavelength region of 330～430Nm. Atomic ratio (x) is a semiconductor diode according to one of claim 1 to 4, characterized in that in the range of 0.03 to 0.08 of europium in the general formula (Eu). Atomic ratio (y) is a semiconductor diode according to any one of claims 1 to 5, characterized in that in the range of 0.001 to 0.01 of samarium (Sm) in the general formula. The semiconductor diode according to any one of claims 1 to 6 , wherein 30 mol% or less of La in the general formula is substituted with at least one element of Y and Gd. 8. The semiconductor diode according to claim 7 , wherein the substitution amount of at least one of Y and Gd with respect to La in the general formula is 5 to 20 mol%. 9. The semiconductor diode according to claim 1, wherein the phosphor is contained in a resin layer. 8. The semiconductor diode comprising a phosphor and a light emitting chip. A display device using a semiconductor diode according to any one of claims 1 to 9.

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