OLED with color change media

• US 7,057,339 B2
• Filed: 04/08/2004
• Issued: 06/06/2006
• Est. Priority Date: 04/08/2004
• Status: Active Grant

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Eastman Kodak Company
• Inventors: Tyan, Yuan-Sheng, Boroson, Michael L., Kahen, Keith B., Winters, Dustin L.
• Primary Examiner(s): Williams, Joseph
• Assistant Examiner(s): Dong, Dalei
• Application Number:
  US10/820,570
• Publication Number:
  US 20050225233A1
• Time in Patent Office: 789 Days
• Field of Search: 313495-506, 313110-113, 428/690, 428/917
• US Class Current: 313/504
• 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 59/35 comprising red-green-blue [RGB] subpixels
• 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 tuned OLED device includes a microcavity structure including a light-emitting layer for producing light, a semitransparent reflector, and a reflector layer disposed on opposite sides of the light-emitting layer, the microcavity structure enhancing on-axis light produced from the light-emitting layer in at least one particular wavelength to produce a desired on-axis viewed color while not substantially enhancing on-axis other wavelengths of such light; and a layer including a color change medium which is responsive to wavelengths of light shorter than the particular wavelength by absorbing such shorter wavelengths of light and emitting light corresponding in color to the particular wavelength, thereby improving the color of the light produced by the OLED device when viewed in an off-axis direction.

Claims

1. A tuned OLED device, comprising:

a) a tuned microcavity structure including a light-emitting layer for producing light, a semitransparent reflector, and a reflector layer disposed on opposite sides of the light-emitting layer, the tuned microcavity structure enhancing on-axis light produced from the light-emitting layer in at least one particular wavelength to produce a desired on-axis viewed color while not substantially enhancing on-axis other wavelengths of such light; and

b) a layer including a color change medium which is responsive to wavelengths of light shorter than the particular wavelength by absorbing such shorter wavelengths of light and emitting light corresponding in color to the particular wavelength, thereby improving the color of the light produced by the OLED device when viewed in an off-axis direction.

2. The tuned OLED device of claim 1 wherein the light-emitting layer produces broadband wavelength light.

3. The tuned OLED device of claim 1 wherein the particular wavelength of on-axis light is in the red, green, or blue portions of the spectrum.

4. The tuned OLED device of claim 1 wherein the color change medium layer is disposed over the semitransparent reflector.

5. The tuned OLED device of claim 4 further including a dielectric stack disposed between the color change medium layer and the semitransparent reflector.

6. The tuned OLED device of claim 1 wherein the reflector also functions as an electrode.

7. The device of claim 1 wherein the semitransparent reflector also functions as an electrode.

8. The tuned OLED device of claim 1 wherein the device is a passive matrix device.

9. The tuned OLED device of claim 1 wherein the device is an active matrix device.

10. The tuned OLED device of claim 1 wherein the microcavity structure further includes a transparent cavity-spacer layer.

11. The tuned OLED device of claim 10 wherein the thickness of the transparent cavity-spacer layer, refractive index of the transparent cavity-spacer layer, or both, are adjusted in conjunction with the thickness and refractive index of the layers of the tuned OLED device to tune the microcavity structure to the desired color.

12. The tuned OLED device of claim 1 wherein the device is bottom-emitting.

13. The tuned OLED device of claim 1 wherein the device is top-emitting.

14. The tuned OLED device of claim 1 further including a color filter.

15. A tuned multicolor OLED device having an array of different color pixels wherein at least two of such different color pixels comprise:

a) common light-emitting layer for each of the at least two such different color pixels that produces light having at least two different particular wavelengths corresponding to the two different colors;

b) two different tuned microcavity structures, wherein each tuned microcavity structure includes a common light-emitting layer for producing light, a semitransparent reflector, and a reflector layer disposed on opposite sides of the light-emitting layer, each tuned microcavity structure enhances one of the particular wavelengths to provide on-axis light having the desired on-axis viewed color while not substantially enhancing other wavelengths of such light in an on-axis direction; and

c) at least one color change medium associated with one of the different tuned microcavity structures which is responsive to wavelength of light shorter than the particular wavelength of the associated microcavity structure by absorbing such shorter wavelengths of light and emitting light corresponding in color to the desired particular wavelength, thereby improving the color of the light produced by the associated microcavity structure when viewed in an off-axis direction.

16. The tuned OLED device of claim 15 wherein the common light-emitting layer produces broadband wavelength light.

17. The tuned OLED device of claim 15 wherein the particular wavelengths of on-axis light are in the red, green, or blue portions of the spectrum.

18. The tuned OLED device of claim 15 wherein the color change medium layer is disposed over the semitransparent reflector.

19. The tuned OLED device of claim 18 further including a dielectric stack disposed between the color change medium layer and the semitransparent reflector.

20. The tuned OLED device of claim 15 wherein the reflector also functions as an electrode for at least one of the pixels.

21. The tuned OLED device of claim 15 wherein the semitransparent reflector also functions as an electrode for one or more of the pixels.

22. The tuned OLED device of claim 15 wherein the device is a passive matrix device.

23. The OLED device of claim 15 wherein the device is an active matrix device.

24. The tuned OLED device of claim 15 wherein at least one pixel further includes a transparent cavity-spacer layer.

25. The tuned OLED device of claim 24 wherein the thickness of the transparent cavity-spacer layer, refractive index of the transparent cavity-spacer layer, or both, are separately adjusted for each different color pixel in conjunction with the thickness and refractive index of the layers of the tuned OLED device to tune the microcavity structure to the desired colors.