LED device comprising thin-film phosphor having two dimensional nano periodic structures
View Patent ↗Disclosed herein is an LED device which comprises a light-emitting diode (LED) and a laminate formed on the LED, the laminate consisting of a substrate and a phosphor thin film laminated on the substrate, wherein the phosphor thin film has a two-dimensional nanoperiodic structure formed in a forward direction of the thin film and has an extinction coefficient of 10 −3 or less. The LED device has higher luminescent efficiency and luminance than conventional LED devices. In addition, since the LED device uses no slurry and a lesser amount of phosphor than conventional LED devices, it is advantageous in terms of optical homogeneity and reduced costs.
1. An LED device, comprising:
a light-emitting diode (LED); and
a laminate formed on the LED, the laminate consisting of a substrate and a phosphor thin film laminated on the substrate,
wherein the phosphor thin film has a two-dimensional nanoperiodic structure formed in a forward direction of the thin film and has an extinction coefficient of 10 −3 or less.
2. The LED device according to claim 1 , wherein the two-dimensional nanoperiodic structure has a period of from 200 nm to 5,000 nm.
3. The LED device according to claim 1 , wherein the two-dimensional nanoperiodic structure has a height of from 10 nm to 5,000 nm.
4. The LED device according to claim 1 , wherein the two-dimensional nanoperiodic structure is engraved or embossed spherical, cylindrical, cuboidal, or triangular prismatic.
5. The LED device according to claim 1 , wherein the surface area ratio of the embossed portions to the engraved portions is in the range of 10˜90%.
6. The LED device according to claim 1 , wherein the phosphor thin film has a planar bottom.
7. The LED device according to claim 1 or 6 , wherein the two-dimensional nanoperiodic structure has a refractive index between 1.8 and 2.5, is made of a transparent material having a refractive index identical to or higher than that of the phosphor thin film, and is formed on top of phosphor thin film.
8. The LED device according to claim 1 , wherein the LED is an InGaN blue LED having a wavelength band of 420˜480 mm, the phosphor thin film is composed of a yellow phosphor exhibiting a luminescence spectrum in the wavelength band of 450˜800 nm, and the LED device emits white light.
9. The LED device according to claim 8 , wherein the yellow phosphor is a YAG:Ce series, Ca-a-SiAlON:Eu series, or Sr 2 SiO 4 :Eu series phosphor.
10. The LED device according to claim 1 , wherein the LED is an InGaN blue LED having a wavelength band of 420˜480 nm, the phosphor thin film includes a two-dimensional nanoperiodic thin film composed of a green phosphor exhibiting a luminescence spectrum in the wavelength band of 450˜650 nm and a two-dimensional nanoperiodic thin film composed of a red phosphor exhibiting a luminescence spectrum in the wavelength band of 550˜800 nm, the two thin films being laminated on each other, and the LED device emits white light.
11. The LED device according to claim 10 , wherein the green phosphor is a SrGa 2 S 4 :Eu series phosphor, and the red phosphor is a SrS:Eu series or Sr 2 Si 5 N 8 :Eu series phosphor.
12. The LED device according to claim 1 , wherein the LED is a UV LED having a wavelength band of 350˜420 nm, the phosphor thin film includes a two-dimensional nanoperiodic phosphor thin film composed of a blue phosphor exhibiting a luminescence spectrum in the wavelength band of 400˜600 nm, a two-dimensional nanoperiodic phosphor thin film composed of a green phosphor exhibiting a luminescence spectrum in the wavelength band of 450˜650 nm, and a two-dimensional nanoperiodic phosphor thin film composed of a red phosphor exhibiting a luminescence spectrum in the wavelength band of 550˜800 nm, the three thin films being laminated on each other, and the LED device emits white light.
13. The LED device according to claim 12 , wherein the blue phosphor is a ZnS:Ag series, BAM:Eu series or Holophosphate:Eu series phosphor, the green phosphor is a ZnS:CuAl series, Zn 2 GeO 4 :Mn series, LaPO 4 :Eu series or CeMgAl 11 O 19 :Tb series phosphor, and the red phosphor is a Gd 2 O 2 S:Eu series or Y 2 O 2 S:Eu series phosphor.
14. The LED device according to claim 1 , wherein the LED is a UV LED having a wavelength band of 350˜420 nm, the phosphor thin film is a two-dimensional nanoperiodic thin film composed of a white phosphor simultaneously emitting both blue light having a wavelength band of 400˜600 nm and light having a wavelength band of 500˜700 nm, and the LED device emits white light.
15. The LED device according to claim 14 , wherein the white phosphor is a Sr 3 MgSi 2 O 8 :Eu,Mn series phosphor.
16. The LED device according to claim 1 , further comprising a transparent binder with a refractive index of 1.4 or greater.
17. The LED device according to claim 1 , wherein the difference in the refractive index of the LED, the substrate and the two-dimensional nanoperiodic structure is 0.4 or less.