Blue light emitting devices that include phosphor-converted blue light emitting diodes

• US 9,219,201 B1
• Filed: 10/31/2014
• Issued: 12/22/2015
• Est. Priority Date: 10/31/2014
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Todorov, Iliya, Seibel, Harry
• Primary Examiner(s): Mandala, Victor A
• Assistant Examiner(s): RUNDIO, REGAN J
• Application Number:
  US14/529,327
• Time in Patent Office: 417 Days
• US Class Current: 1/1
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body
• CPC Class Codes: H01L 33/54 having a particular shape

Abstract

Light emitting devices include a blue LED that emits blue light having a peak wavelength between 430 nanometers and 480 nanometers and a recipient luminophoric medium that includes luminescent materials that down-convert a portion of the blue light emitted by the blue LED to light having a peak wavelength that is between about 500 nanometers and about 545 nanometers. The combination of the blue light emitted by the blue LED and the light emitted by the luminescent materials in the recipient luminophoric medium comprises light that is perceived as blue light having a color point that falls within the region on the 1931 CIE Chromaticity Diagram defined by ccx, ccy chromaticity coordinates of (0.1355, 0.0399), (0.175, 0.0985), (0.1743 0.1581), (0.1096, 0.0868), (0.1355, 0.0399).

Claims

1. A light emitting device, comprising:

a blue light emitting diode (“

LED”

) that emits light having a peak wavelength between 430 nanometers and 480 nanometers; and

a recipient luminophoric medium that is configured to down-convert at least some of the blue light emitted by the blue LED, the recipient luminophoric medium including luminescent materials that down-convert a portion of the blue light emitted by the blue LED to light having a peak wavelength that is between about 500 nanometers and about 545 nanometers,

wherein the combination of the blue light emitted by the blue LED and the light emitted by the luminescent materials in the recipient luminophoric medium comprises light that is perceived as blue light having a color point that falls within the region on the 1931 CIE Chromaticity Diagram defined by ccx, ccy chromaticity coordinates of (0.1355, 0.0399), (0.175, 0.0985), (0.1743 0.1581), (0.1096, 0.0868), (0.1355, 0.0399).

2. The light emitting device of claim 1, wherein less than 5% of the blue light emitted by the blue LED is down-converted by the luminescent materials in the recipient luminophoric medium.

3. The light emitting device of claim 1, wherein the luminescent materials down-convert a portion of the blue light emitted by the blue LED to light having a peak wavelength that is between about 530 nanometers and about 545 nanometers.

4. The light emitting device of claim 1, wherein the combination of the blue light emitted by the blue LED and the light emitted by the luminescent materials in the recipient luminophoric medium has a radiometric emission spectra that has a spectral power output throughout the wavelength range of 500 nanometers to 570 nanometers that is between 2% and 9% of the spectral power output at the peak wavelength of the blue LED.

5. The light emitting device of claim 1, wherein the combination of the blue light emitted by the blue LED and the light emitted by the luminescent materials in the recipient luminophoric medium has a radiometric emission spectra that has a spectral power output throughout the wavelength range of 520 nanometers to 560 nanometers that is between 3% and 6% of the spectral power output at the peak wavelength of the blue LED.

6. The light emitting device of claim 1, wherein the recipient luminophoric medium is coated to an average thickness of less than 20 microns on a top surface of the blue LED.

7. The light emitting device of claim 1, wherein the luminescent materials comprise LuAG:

Ce phosphor particles.

8. The light emitting device of claim 1, wherein the luminescent materials comprise narrowband luminescent materials having a full width half maximum width of less than 30 nanometers.

9. The light emitting device of claim 1, wherein the blue LED has a peak wavelength between 450 and 458 nanometers.

10. The light emitting device of claim 1, wherein the recipient luminophoric medium is formed directly on a major surface of the blue LED and includes a plurality of recesses that expose portions of the major surface of the LED.

11. The light emitting device of claim 10, wherein the recesses are in a predetermined pattern.

12. A light emitting device, comprising:

a blue light emitting diode (“

LED”

) that emits blue light having a peak wavelength between 430 nanometers and 465 nanometers; and

a recipient luminophoric medium that is configured to down-convert at least some of the blue light emitted by the blue LED, the recipient luminophoric medium including luminescent materials that down-convert a portion of the blue light emitted by the blue LED to light having a peak wavelength that is between about 500 nanometers and about 545 nanometers,

wherein less than 5% of the blue light emitted by the blue LED is down-converted by the luminescent materials in the recipient luminophoric medium.

13. The light emitting device of claim 12, wherein the blue LED emits blue light having a peak wavelength between 450 nanometers and 458 nanometers.

14. The light emitting device of claim 12, wherein the luminescent materials down-convert a portion of the blue light emitted by the blue LED to light having a peak wavelength that is between about 530 nanometers and about 545 nanometers.

15. The light emitting device of claim 12, wherein the combination of the blue light emitted by the blue LED and the light emitted by the luminescent materials in the recipient luminophoric medium has a radiometric emission spectra that has a spectral power output throughout the wavelength range of 500 nanometers to 570 nanometers that is between 2% and 9% of the spectral power output at the peak wavelength of the blue LED.

16. The light emitting device of claim 12, wherein the combination of the blue light emitted by the blue LED and the light emitted by the luminescent materials in the recipient luminophoric medium comprises light that is perceived as blue light having a color point that falls within the region on the 1931 CIE Chromaticity Diagram defined by ccx, ccy chromaticity coordinates of (0.16, 0.07621), (0.175, 0.0985), (0.1743 0.1581), (0.16, 0.1423), (0.16, 0.07621).

17. A light emitting device, comprising:

a blue light emitting diode (“

LED”

) that emits blue light having a peak wavelength between 430 nanometers and 465 nanometers; and

a recipient luminophoric medium that is configured to down-convert at least some of the blue light emitted by the blue LED, the recipient luminophoric medium including luminescent materials that down-convert a portion of the blue light emitted by the blue LED to light having a peak wavelength that is between about 500 nanometers and about 545 nanometers,

wherein the combination of the blue light emitted by the blue LED and the light emitted by the luminescent materials of the recipient luminophoric medium has a radiometric emission spectra that has a spectral power output in the wavelength range of 500 nanometers to 570 nanometers that is between 2% and 9% of the spectral power output at the peak wavelength of the blue LED.

18. The light emitting device of claim 17, wherein less than 5% of the blue light emitted by the blue LED is down-converted by the luminescent materials in the recipient luminophoric medium.

19. The light emitting device of claim 17, wherein the luminescent materials down-convert a portion of the blue light emitted by the blue LED to light having a peak wavelength that is between about 530 nanometers and about 545 nanometers.

20. The light emitting device of claim 17, wherein the combination of the blue light emitted by the blue LED and the light emitted by the luminescent materials in the recipient luminophoric medium has a radiometric emission spectra that has a spectral power output throughout the wavelength range of 520 nanometers to 560 nanometers that is between 3% and 6% of the spectral power output at the peak wavelength of the blue LED.

21. The light emitting device of claim 17, wherein a bottom surface of the blue LED is mounted on a mounting substrate and wherein the recipient luminophoric medium is coated to an average thickness of less than 20 microns on a top surface of the blue LED.

22. A light emitting device, comprising:

a blue light emitting diode (“

LED”

) that emits blue light having a peak wavelength between 450 nanometers and 458 nanometers; and

a recipient luminophoric medium that is configured to down-convert at least some of the blue light emitted by the blue LED, the recipient luminophoric medium including luminescent materials that down-convert a portion of the blue light emitted by the blue LED to light having a peak wavelength that is between about 515 nanometers and about 545 nanometers,

wherein a bottom surface of the blue LED is mounted on a mounting substrate and wherein the recipient luminophoric medium is coated to an average thickness of less than 20 microns on a top surface of the blue LED, and

wherein less than 10% of the blue light emitted by the blue LED is down-converted by the luminescent materials in the recipient luminophoric medium.

23. The light emitting device of claim 22, wherein the luminescent materials comprise narrowband luminescent materials having a full width half maximum width of less than 30 nanometers.

24. The light emitting device of claim 22, wherein the combination of the blue light emitted by the blue LED and the light emitted by the luminescent materials in the recipient luminophoric medium comprises light that is perceived as blue light having a color point that falls within the region on the 1931 CIE Chromaticity Diagram defined by ccx, ccy chromaticity coordinates of (0.16, 0.07621), (0.175, 0.0985), (0.1743 0.1581), (0.16, 0.1423), (0.16, 0.07621).

25. The light emitting device of claim 22, wherein the combination of the blue light emitted by the blue LED and the light emitted by the luminescent materials in the recipient luminophoric medium has a radiometric emission spectra that has a spectral power output throughout the wavelength range of 500 nanometers to 570 nanometers that is between 2% and 9% of the spectral power output at the peak wavelength of the blue LED.