LED device having improved light output

• US 7,893,612 B2
• Filed: 02/27/2008
• Issued: 02/22/2011
• Est. Priority Date: 02/27/2008
• Status: Active Grant

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Inventors: Cok, Ronald S.
• Primary Examiner(s): Williams; Joseph L
• Assistant Examiner(s): QUARTERMAN, KEVIN J
• Application Number:
  US12/037,961
• Publication Number:
  US 20090212694A1
• Time in Patent Office: 1,091 Days
• Field of Search: 313498-512, 313/112, 313/113
• US Class Current: 313/506
• 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 59/12 Active-matrix OLED [AMOLED] displays
• 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 diode device that includes a first group of sub-pixels each subpixel comprising a reflective electrode and a second electrode formed over a substrate with an unpatterned light-emitting layer formed between the reflective electrode and the second electrode, thus forming a first optical cavity having a first cavity length. Either the reflective or second electrode is patterned to form two or more independently-controllable, light-emitting sub-pixels. A second group of sub-pixels, each comprising a reflective electrode and a second electrode formed over the substrate. An unpatterned light-emitting layer is formed between the reflective electrode and the second electrode to comprise a second optical cavity having a second cavity length different from the first cavity length of the first optical cavity. Either the reflective or second electrode is patterned to form one or more independently-controllable, light-emitting sub-pixels.

Claims

1. A light-emitting diode device, comprising:

a) a first group of differently colored sub-pixels each comprising a reflective electrode and a second electrode formed over a substrate with an unpatterned light-emitting layer formed between the reflective electrode and the second electrode to comprise a first optical cavity having a first cavity length, and wherein either the reflective or second electrode is patterned to form two or more independently-controllable, differently colored light-emitting sub-pixels; and

b) a second group of sub-pixels each comprising the reflective electrode and the second electrode formed over the substrate with the unpatterned light-emitting layer formed between the reflective electrode and the second electrode to comprise a second optical cavity having a second cavity length different from the first cavity length of the first optical cavity, and wherein either the reflective or second electrode is patterned to form one or more independently-controllable, light-emitting sub-pixels,

wherein the second electrode of either group is transparent and further comprising a low-index layer adjacent the second electrode having an optical index lower than the optical index of the second, transparent electrode.

2. The light-emitting diode device of claim 1, wherein the reflective electrode of either group is formed between the substrate and the second electrode of either group.

3. The light-emitting diode device of claim 1, wherein the second electrode of either group is formed between the substrate and the reflective electrode of either group.

4. The light-emitting diode device of claim 1 further comprising an optical spacer located between the reflective and second electrodes of the independently-controllable, light-emitting sub-pixels of either, or both, of the first or second group of light-emitting sub-pixels.

5. The light-emitting diode device of claim 4, wherein the optical spacer is a layer between the reflective and second electrodes.

6. The light-emitting diode device of claim 4, wherein either, or both, of the reflective or second electrodes of the independently-controllable, light-emitting sub-pixels in the first or second groups comprises a transparent, conductive layer forming an optical spacer.

7. The light-emitting diode device of claim 4, wherein the reflective and second electrodes and the unpatterned light-emitting layer comprise an organic light-emitting diode (OLED).

8. The light-emitting diode device of claim 1 further comprising color filters located in correspondence with one or more of the independently-controllable, light-emitting sub-pixels of either group to filter the light emitted by the independently-controllable, light-emitting sub-pixels.

9. The light-emitting diode device of claim 8, wherein the first group includes independently-controllable, light-emitting sub-pixels having a color filter of a first color and also includes independently-controllable, light-emitting sub-pixels having a second color filter of a second color different from the first color.

10. The light-emitting diode device of claim 8, wherein the first group includes independently-controllable, light-emitting sub-pixels having a color filter of a first color and the second group includes independently-controllable, light-emitting sub-pixels having a second color filter of a second color different from the first color.

11. The light-emitting diode device of claim 8, wherein either the first or second group includes independently-controllable, light-emitting sub-pixels having a color filter and also includes sub-pixels having no color filter.

12. The light-emitting diode device of claim 1, wherein the unpatterned light-emitting layer emits white light having a spectrum with at least two peaks.

13. The light-emitting diode device of claim 12, wherein the two largest spectral peaks are blue and yellow or cyan and red.

14. The light-emitting diode device of claim 1, wherein the independently-controllable, light-emitting sub-pixels in one group emit red and green light and the sub-pixels in the other group emit blue light.

15. The light-emitting diode device of claim 14, wherein the independently-controllable, light-emitting sub-pixels in the group that emits red and green light also include sub-pixels that emit yellow light.

16. The light-emitting diode device of claim 14, wherein the independently-controllable, light-emitting sub-pixels that emit red and green light include red and green color filters, respectively.

17. The light-emitting diode device of claim 14, wherein the independently-controllable, light-emitting sub-pixels that emit blue light include blue color filters.

18. The light-emitting diode device of claim 1, further comprising an independently-controllable, light-emitting sub-pixel having the first optical cavity in a first portion of the independently-controllable, light-emitting sub-pixel and the second optical cavity in a second portion of the independently-controllable, light-emitting sub-pixel and wherein light from the first and second optical cavities have different complementary colors and the independently-controllable, light-emitting sub-pixel emits perceptually white light.

19. The light-emitting diode device of claim 14, wherein the independently-controllable, light-emitting sub-pixels in the group that emits red and green light also include sub-pixels that emit substantially white light by having two different complementary colors.