Multilayered white light emitting diode using quantum dots and method of fabricating the same
View Patent ↗A multilayered white light emitting diode and a method of fabricating the same include forming a phosphor mixture layer including a green phosphor and a blue phosphor on a UV light emitting diode and forming a red quantum dot layer on the phosphor mixture layer. In the white light emitting diode of the present invention, the quantum dots are excited by green and blue visible light, thus increasing luminescence efficiency and realizing stable white light. Moreover, the white light emitting diode can be widely used as a light source having high output and high efficiency, thus being capable of substituting for a backlight unit of an illumination device or display device.
1. A multilayered white light emitting diode comprising
a UV light emitting diode for emitting UV light;
a phosphor mixture layer consisting essentially of a green phosphor, a blue phosphor and an organic binder, the phosphor mixture layer formed on the UV light emitting diode; and
a red quantum dot layer formed on the phosphor mixture layer.
2. The light emitting diode as set forth in claim 1 , wherein the green phosphor comprises at least one selected from the group consisting of BaMgAl 10 O 17 :Eu,Mn, Zn 2 SiO 4 :Mn, (Zn,A) 2 SiO 4 :Mn (where A is an alkali earth metal), MgAl,(O y :Mn (where x=an integer from 1 to 10 and y=an integer from 1 to 30), LaMgAl x O y :Tb (where x=an integer from 1 to 14 and y=an integer from 8 to 47), ReBO 3 :Tb (where Re is a rare earth element selected from the group consisting of Sc, Y, La, Ce, and Gd) and (Y,Gd)BO 3 :Tb.
3. The light emitting diode as set forth in claim 1 , wherein the blue phosphor comprises at least one selected from the group consisting of Sr(PO 4 ) 3 Cl:Eu 2+ , ZnS:Ag, Cl, CaMgSi 2 O 6 :Eu, CaWO 4 :Pb and Y 2 SiO 5 :Eu.
4. The light emitting diode as set forth in claim 1 , wherein the phosphor mixture layer comprises the blue phosphor and the green phosphor mixed at a ratio of 3:1.
5. The light emitting diode as set forth in claim 1 , wherein the red quantum dot layer comprises quantum dots selected from the group consisting of Group II-VI compound semiconductor nanocrystals, Group III-V compound semiconductor nanocrystals and mixtures thereof.
6. The light emitting diode as set forth in claim 5 , wherein the Group II-VI compound semiconductor nanocrystals include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe and HgTe, and the Group III-V compound semiconductor nanocrystals include GaN, GaP, GaAs, InP and InAs.
7. The light emitting diode as set forth in claim 1 , wherein the red quantum dot layer has a thickness of 3 mm or less.
8. A method of fabricating a multilayered white light emitting diode, the method comprising:
forming a phosphor mixture layer on a UV light emitting diode chip which emits UV light, wherein the phosphor layer consists essentially of a green phosphor, a blue phosphor and an organic binder, and emits green light and blue light; and
forming a red quantum dot layer on the phosphor mixture layer.
9. The method as set forth in claim 8 , wherein the forming the phosphor mixture layer is conducted using drop casting, spin coating, dip coating, spray coating, flow coating or screen printing.
10. The method as set forth in claim 8 , wherein the phosphor mixture layer is dried at about 100° C. to about 150° C.
11. The method as set forth in claim 8 , wherein a ratio of the blue phosphor and green phosphor to the organic binder is about 1:1 to about 1:3.
12. The method as set forth in claim 8 , wherein the red quantum dot layer comprises a red quantum dot and an organic binder.
13. The method as set forth in claim 12 , wherein a ratio of the red quantum dot to the organic binder is 1:10000.