LED device having improved light output

• US 8,207,668 B2
• Filed: 05/21/2010
• Issued: 06/26/2012
• Est. Priority Date: 09/17/2007
• Status: Active Grant

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Inventors: Cok, Ronald S., Kane, Paul J., Miller, Michael E.
• Primary Examiner(s): Macchiarolo, Peter
• Application Number:
  US12/784,827
• Publication Number:
  US 20100231485A1
• Time in Patent Office: 767 Days
• Field of Search: 313498-512
• US Class Current: 313/506
• CPC Class Codes: H10K 50/852 comprising a resonant cavity structure, e.g. Bragg reflector pair
• CPC Class Codes: H10K 59/30 Devices specially adapted for multicolour light emission
• 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 white light-emitting microcavity light-emitting diode device, comprising:

• • a) A reflective electrode and a semi-transparent electrode formed over a substrate and an unpatterned white-light-emitting layer formed between the reflective electrode and the semi-transparent electrode, the reflective electrode, semi-transparent electrode, and unpatterned white-light-emitting layer forming an optical cavity. Either the reflective or semi-transparent electrode is patterned to form independently-controllable light-emitting sub-pixel elements.
  • b) Color filters are formed over a side of the semi-transparent electrodes opposite the unpatterned white light-emitting-layer in correspondence with the independently-controllable light-emitting elements to form colored sub-pixels. At least one independently-controllable light-emitting element has at least two commonly-controlled portions that together emit substantially white light to form a white sub-pixel.
  • c) The optical cavity of one or more of the commonly-controlled portions of the white sub-pixel comprises optical microcavities tuned to emit light at a different complementary wavelength at an emission angle.

Claims

1. A white light-emitting microcavity light-emitting diode device, comprising:

a) a substrate;

b) a reflective electrode and a semi-transparent electrode formed over the substrate and an unpatterned white-light-emitting layer formed between the reflective electrode and the semi-transparent electrode, the reflective electrode, semi-transparent electrode, and unpatterned white-light-emitting layer forming an optical cavity, and wherein either the reflective or semi-transparent electrode is patterned to form a plurality of independently-controllable light-emitting sub-pixel elements; and

c) a plurality of color filters formed over a side of the semi-transparent electrodes opposite the unpatterned white light-emitting-layer in correspondence with the independently-controllable light-emitting elements to form colored sub-pixels, the plurality of color filters having at least two different colors and wherein at least one independently-controllable light-emitting element has at least two commonly-controlled portions that together emit substantially white light to form a white sub-pixel;

d) wherein the optical cavity of one or more of the commonly-controlled portions of the white sub-pixel comprises a plurality of optical microcavities, each optical microcavity tuned to emit light at a different complementary wavelength and emission angle, and

e) wherein one of the commonly-controlled portions of the white sub-pixel is tuned to emit light having a peak wavelength greater than 550 nm at a normal angle and further comprising a color filter formed over the one of the commonly-controlled portions of the white sub-pixel, the color filter absorbing a substantial amount of the light having a wavelength less than 550 nm,

wherein the optical cavities of the colored sub-pixels are tuned to an approximate peak wavelength corresponding to the peak transmission wavelength of the corresponding color filter.

2. The device of claim 1 wherein one of the commonly-controlled portions of the white sub-pixel emits substantially blue or cyan light at a normal angle with respect to the substrate and another of the commonly-controlled portions emits substantially yellow, orange, or red light at a normal angle with respect to the substrate.

3. The device of claim 2 wherein one of the commonly-controlled portions of the white sub-pixel emits light having a peak wavelength emission greater than 550 nm at a normal angle with respect to the substrate and another of the at-least-two commonly-controlled portions of the white sub-pixel emits light having a peak wavelength emission less than 500 nm at a normal angle with respect to the substrate.

4. The device of claim 2 further comprising a color filter formed over one of the commonly-controlled portions that transmits light emitted at a normal angle with respect to the substrate and absorbs light emitted at an angle other than the normal.

5. The device of claim 1 wherein one of the commonly-controlled portions of the white sub-pixel has a different sized-area from another of the commonly-controlled portions of the white sub-pixel.

6. The device of claim 1 wherein at least one of the commonly-controlled portions of the white sub-pixel is tuned to emit light at a peak wavelength different from the peak wavelengths of the colored sub-pixels.

7. The device of claim 1 wherein the emission of the white sub-pixel is tuned to emit light at a selected device white-point.

8. The device of claim 1 wherein the emission of the white sub-pixel is tuned to emit light at a white-point other than a selected white point of the device.

9. The device of claim 1 wherein the emission of the white sub-pixel is tuned to minimize the difference between the average emission of the white sub-pixel and a selected device white-point at more than one angle.

10. The device of claim 1 wherein the wavelength of the light emitted from each of the commonly-controlled portions of the white sub-pixel changes at different viewing angles.

11. The device of claim 1 wherein the optical microcavities of the white sub-pixels are tuned to one or more peak wavelengths approximately corresponding to the peak emission wavelengths of the white-light-emitting layer.

12. The device of claim 1 wherein the peak emission wavelengths of the white-light-emitting layer are matched to the peak transmission wavelength of the corresponding color filter.

13. The light-emitting diode device of claim 1 wherein the optical micro-cavities of the white sub-pixel are tuned to emit red, green, and blue light, or yellow and blue light, or red and cyan light, or orange and cyan light.

14. The light-emitting diode device of claim 1 wherein the white light-emitting layer emits light having a spectrum with two or more peaks.

15. The light-emitting diode device of claim 1, wherein the white light-emitting layer comprises organic materials or inorganic quantum dots formed in a poly-crystalline semiconductor matrix.

16. A white light-emitting microcavity light-emitting diode device, comprising:

a) a substrate;

b) a reflective electrode and a semi-transparent electrode formed over the substrate and an unpatterned white-light-emitting layer formed between the reflective electrode and the semi-transparent electrode, the reflective electrode, semi-transparent electrode, and unpatterned white-light-emitting layer forming an optical cavity, and wherein either the reflective or semi-transparent electrode is patterned to form a plurality of independently-controllable light-emitting sub-pixel elements; and

c) a plurality of color filters formed over a side of the semi-transparent electrodes opposite the unpatterned white light-emitting-layer in correspondence with the independently-controllable light-emitting elements to form colored sub-pixels, the plurality of color filters having at least two different colors and wherein at least one independently-controllable light-emitting element has at least two commonly-controlled portions that together emit substantially white light to form a white sub-pixel;

d) wherein the optical cavity of one or more of the commonly controlled portions of the white sub-pixel comprises a plurality of optical microcavities, each optical microcavity tuned to emit light at a different complementary wavelength at multiple emission angles, and

e) wherein one of the commonly-controlled portions of the white sub-pixel is tuned to emit light having a peak wavelength greater than 550 nm at a normal angle and further comprising a color filter formed over the one of the commonly-controlled portions of the white sub-pixel, the color filter absorbing a substantial amount of the light having a wavelength less than 550 nm.

17. A method of making an LED device, comprising the steps of:

a) providing a substrate;

b) forming a reflective electrode and a semi-transparent electrode over the substrate and forming an unpatterned white-light-emitting layer between the reflective electrode and the semi-transparent electrode, the reflective electrode, semi-transparent electrode, and unpatterned white-light-emitting layer forming an optical cavity, and wherein either the reflective or semi-transparent electrode is patterned to form a plurality of independently-controllable light-emitting sub-pixel elements; and

c) forming a plurality of color filters over a side of the semi-transparent electrodes opposite the unpatterned white light-emitting-layer in correspondence with the independently-controllable light-emitting elements to form colored sub-pixels, the plurality of color filters having at least two different colors and wherein at least one independently-controllable light-emitting element has at least two commonly-controlled portions that together emit substantially white light to form a white sub-pixel;

d) wherein the optical cavity of one or more of the commonly-controlled portions of the white sub-pixel comprises a plurality of optical microcavities, each optical microcavity tuned to emit light at a different complementary wavelength at an emission angle, and

e) wherein one of the commonly-controlled portions of the white sub-pixel is tuned to emit light having a peak wavelength greater than 550 nm at a normal angle and further comprising a color filter formed over the one of the commonly-controlled portions of the white sub-pixel, the color filter absorbing a substantial amount of the light having a wavelength less than 550 nm.