LED DEVICE HAVING IMPROVED LIGHT OUTPUT

• US 20090102352A1
• Filed: 10/22/2007
• Published: 04/23/2009
• Est. Priority Date: 10/22/2007
• Status: Active Grant

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Inventors: Shore, Joel D., Cok, Ronald S.
• Granted Patent: US 8,063,552 B2
• Time in Patent Office: Days
• US Class Current: 313/498
• CPC Class Codes: H05B 33/22 characterised by the chemical or physical composition or the arrangement of auxiliary dielectric or reflective layers
• CPC Class Codes: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: H10K 50/852 comprising a resonant cavity structure, e.g. Bragg reflector pair
• CPC Class Codes: H10K 59/351 comprising more than three subpixels, e.g. red-green-blue-white [RGBW]
• CPC Class Codes: H10K 59/38 comprising colour filters or colour changing media [CCM]
• CPC Class Codes: H10K 59/876 comprising a resonant cavity structure, e.g. Bragg reflector pair

Abstract

A light-emitting optical cavity light-emitting diode device, comprising:

• • a) a substrate;
  • b) a reflective electrode formed over the substrate;
  • c) an unpatterned light-emitting layer formed over the reflective electrode;
  • d) a transparent electrode formed over the unpatterned light-emitting layer;
  • e) one or more different optical spacers, defining at least two different optical path lengths, are formed in different locations over the substrate, between the reflective electrode and the transparent electrode; and
  • f) a low-index layer formed over the transparent electrode.

Claims

1. A light-emitting diode device, comprising:

a) a substrate;

b) a reflective electrode formed over the substrate;

c) an unpatterned light-emitting layer formed over the reflective electrode;

d) a transparent electrode formed over the unpatterned light-emitting layer;

e) one or more different optical spacers, defining at least two different optical path lengths, are formed in different locations over the substrate, between the reflective electrode and the transparent electrode; and

f) a low-index layer formed over the transparent electrode.

2. The light-emitting diode device of claim 1, wherein a combination of light emitted from the different locations of the different optical path lengths, is white and a combined color change of the combined light emitted over a range of angles is less than a color change of the light emitted over the range of angles from at least one of the different locations.

3. The light-emitting diode device of claim 1, wherein the reflective or transparent electrode is patterned to form an independently controllable sub-pixel corresponding to each optical spacer.

4. The light-emitting diode device of claim 1, wherein the reflective or transparent electrode is patterned to form an independently controllable sub-pixel corresponding to two or more different locations having different optical spacers.

5. The light-emitting diode device of claim 1, further comprising one or more color filters located over at least one, but not all, of the different locations.

6. The light-emitting diode device of claim 1, wherein at least one optical spacer forms an optically constructive interference pattern at a frequency corresponding to a primary color frequency and at least one other optical spacer forms an optically constructive interference pattern at a frequency corresponding to a frequency of a color complementary to the primary color frequency.

7. The light-emitting diode device of claim 6, wherein the two different color complementary frequencies are blue and yellow or red and cyan.

8. The light-emitting diode device of claim 6, wherein the two or more different optical spacers form optically constructive interference patterns at two different wavelengths that differ by less than 150 nm.

9. The light-emitting diode device of claim 1, wherein the unpatterned light-emitting layer emits white light.

10. The light-emitting diode device of claim 9, wherein the white light has a spectrum with frequency peaks and at least one optical spacer forms an optically constructive interference pattern at a frequency corresponding to a spectral frequency peak of the white light.

11. The light-emitting diode device of claim 1, wherein the low-index layer has an optical index of less than 1.1.

12. The light-emitting diode device of claim 1, wherein one location emits red light, a second location emits green light, and a third location emits blue light.

13. The light-emitting diode device of claim 12, further comprising a fourth location that emits yellow, cyan, or magenta light.

14. The light-emitting diode device of claim 1, wherein at least one of the transparent or reflective electrodes is patterned to form independently controllable sub-pixels and at least one sub-pixel comprises two or more different locations having different optical spacers.

15. The light-emitting diode device of claim 14, wherein the two or more different locations of the at least one sub-pixel emit complementary colors of light that combine to form a substantially white light.

16. The light-emitting diode device of claim 1, wherein the low-index layer is an air-gap.

17. The light-emitting diode device of claim 15, wherein the complementary colors of light are red, yellow, and blue.

18. The light-emitting diode device of claim 1, wherein at least one location emits red light, at least one location emits green light, at least one location emits blue light, and at least one location emits white or colored light with a luminous efficiency higher than that of least one of the red, green, and blue locations.

19. A method of forming a light-emitting diode device, comprising the steps of:

a) providing a substrate;

b) forming a reflective electrode over the substrate;

c) forming an unpatterned light-emitting layer over the reflective electrode;

d) forming a transparent electrode over the unpatterned light-emitting layer;

e) forming one or more different optical spacers that define at least two different optical path lengths in different locations over the substrate, between the reflective electrode and the transparent electrode; and

f) forming a low-index layer over the transparent electrode.

20. A display system, comprising:

a) an LED device having at least four, or more, differently colored sub-pixels, the LED device comprising;

i) a substrate;

ii) a reflective electrode formed over the substrate;

iii) an unpatterned light-emitting layer formed over the reflective electrode;

iv) a transparent electrode formed over the unpatterned light-emitting layer;

v) one or more different optical spacers, defining at least two different optical path lengths, are formed in different locations over the substrate, between the reflective electrode and the transparent electrode;

vi) a low-index layer formed over the transparent electrode;

b) an input signal having three components; and

c) a controller for receiving the input signal, converting the input signal to a converted four-or-more component signal, and driving the LED device with the converted four-or-more component signal.