Light emitting device having peripheral emissive region

• US 8,450,730 B2
• Filed: 02/02/2011
• Issued: 05/28/2013
• Est. Priority Date: 03/31/2010
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Inventors: Forrest, Stephen R.
• Primary Examiner(s): Mandala, Victor A
• Application Number:
  US13/019,753
• Publication Number:
  US 20110241046A1
• Time in Patent Office: 846 Days
• Field of Search: 257/40, 257/98, 257/E51.018
• US Class Current: 257/40
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H10K 2102/3023 Direction of light emission
• CPC Class Codes: H10K 59/90 Assemblies of multiple devices comprising at least one organic light-emitting element

Abstract

Light emitting devices are provided that include one or more OLEDs disposed only on a peripheral region of the substrate. An OLED may be disposed only on a peripheral region of a substantially transparent substrate and configured to emit light into the substrate. Another surface of the substrate may be roughened or include other features to outcouple light from the substrate. The edges of the substrate may be beveled and/or reflective. The area of the OLED(s) may be relatively small compared to the substrate surface area through which light is emitted from the device. One or more OLEDs also or alternatively may be disposed on an edge of the substrate about perpendicular to the surface of the substrate through which light is emitted, such that they emit light into the substrate. A mode expanding region may be included between each such OLED and the substrate.

Claims

1. A device comprising:

a transparent substrate comprising a first surface and a second surface; and

an organic light emitting device disposed only on a peripheral region of the transparent substrate and configured to emit light into the transparent substrate.

2. The device of claim 1, wherein the organic light emitting device is disposed on, and about parallel to, the first surface.

3. The device of claim 1, wherein the second surface is roughened.

4. The device of claim 3, wherein the roughened surface has a linear gradient having a higher degree of roughening at the center of the surface than at peripheral regions of the surface.

5. The device of claim 1, wherein at least one edge of the substrate is beveled.

6. The device of claim 5, wherein the beveled edge is coated with a metal.

7. The device of claim 5, wherein light emitted through the beveled edge has a brightness not more than 100% of light emitted from the second surface.

8. The device of claim 5, wherein light emitted through the beveled edge has a brightness of at least 100% of light emitted from the second surface.

9. The device of claim 5, wherein light emitted through the beveled edge has a brightness that is within 10% of the brightness of light emitted from the second surface.

10. The device of claim 1, wherein the angle of the beveled edge is sufficient to achieve substantially total internal reflection of light emitted by the organic light emitting device at the interior surface of the edge.

11. The device of claim 1, wherein the organic light emitting device is disposed at an angle that directs a majority of light emitted by the organic light emitting device from the organic light emitting device toward the center of the device.

12. The device of claim 1, wherein the device is flexible.

13. The device of claim 1, wherein the second surface has a surface area A, the device emits light at a total brightness B, the organic light emitting device has an operating brightness W>

B, and the organic light emitting device has a surface area of not more than about (B/W)A.

14. The device of claim 1, wherein the organic light emitting device is substantially perpendicular to the second surface.

15. The device of claim 14, further comprising:

a second organic light emitting device disposed on a second edge of the device, the second edge being substantially perpendicular to the first surface and to the second surface, and separate from the first edge.

16. The device of claim 14, further comprising a mode expanding region disposed between the first edge and the substantially transparent substrate.

17. The device of claim 16, wherein the mode expanding surface is defined by a reflective surface adjacent to the first edge.

18. The device of claim 17, wherein the reflective surface is coated with a metal.

19. The device of claim 17, wherein the reflective surface is disposed at an angle to cause substantially total internal reflection of light emitted by the organic light emitting device within the mode expanding region.

20. The device of claim 14, wherein the roughened surface has a linear gradient having a higher degree of roughening at the center of the surface than at the peripheral regions of the surface.

21. The device of claim 14, wherein the device is flexible.

22. A light-emitting device constructed to emit light at a brightness B, the device comprising:

a substantially transparent substrate comprising a first surface with surface area A and a roughened second surface; and

an organic light emitting device disposed on the first side of the transparent substrate, the organic light emitting device having an operating brightness W>

B and a surface area of not more than about (B/W)A,

wherein B/W is not more than about 0.2.

23. The device of claim 22, wherein B/W is not more than about 0.1.