Organic laser

• US 20080067530A1
• Filed: 08/29/2006
• Published: 03/20/2008
• Est. Priority Date: 08/29/2006
• Status: Active Grant

• Current Assignee: The Trustees of Princeton University (Princeton University)
• Original Assignee: The Trustees of Princeton University (Princeton University)
• Inventors: Forrest, Stephen, Giebink, Noel
• Granted Patent: US 7,724,796 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01S 5/041 Optical pumping
• CPC Class Codes: H01S 5/36 comprising organic materials
• CPC Class Codes: H10K 50/00 Organic light-emitting devices integrated devices or assemblies of multiple devices H10K59/00, H10K65/00; organic semiconductor lasers H01S5/36
• CPC Class Codes: H10K 59/40 OLEDs integrated with touch screens

Abstract

A device comprising an organic light emitting layer may be optically pumped to create excited states within the layer. When an electric field is applied across the layer, the excited states may dissociate into geminate polaron pairs within the organic layer. The dissociated states may change back to excitons when the electric field is rapidly reduced or removed. The organic light emitting layer may be optically pumped by an adjacent OLED, allowing for an electrically-driven device.

Claims

1. A method of producing light, comprising:

optically pumping an organic light emitting layer while applying an electric field across the organic layer; and

rapidly changing the electric field to produce light from the organic layer;

wherein the light produced by the organic layer when the electric field is rapidly changed has a higher intensity than light produced by the organic layer when the organic layer is optically pumped in the absence of the electric field.

2. The method of claim 1, wherein the organic layer is a small molecule organic layer.

3. The method of claim 1, wherein the organic light emitting layer is continuously pumped.

4. The method of claim 1, wherein changing the electric field comprises reducing the magnitude of the electric field.

5. The method of claim 4, wherein the electric field is reduced over a time interval of about 100 ps to about 10 ns.

6. The method of claim 5, wherein the electric field is reduced over a time interval of about 1 ns to about 10 ns.

7. The method of claim 4, wherein the magnitude of the electric field is reduced to about zero.

8. The method of claim 1, wherein changing the electric field comprises changing the direction of the electric field.

9. The method of claim 1, wherein the electric field is changed at a frequency of about 0.1 to about 100 Hz.

10. The method of claim 1, wherein the organic light emitting layer comprises a first organic material doped with a second organic material.

11. The method of claim 10, wherein the second organic material is an organic small molecule material.

12. The method of claim 1, wherein the wavelength of light used to pump the organic layer is shorter than the peak wavelength of the light produced by the organic layer when the electric field is changed.

13. The method of claim 1, wherein optically pumping the organic layer comprises activating an OLED disposed adjacent to the organic layer.

14. The method of claim 1, wherein geminate polaron-pair states accumulate in the organic layer while the field is applied.

15. The method of claim 14, wherein changing the electric field causes the polaron-pair states to reform excitons, causing the organic layer to emit light.

16. The method of claim 1, wherein the organic layer is pumped using a source that provides energy to the organic layer at a linear rate.

17. The method of claim 1, wherein the magnitude of the electric field applied across the organic layer while optically pumping the organic layer is about 0.1 MV/cm to about 3.0 MV/cm before the electric field is changed.

18. The method of claim 1, wherein the light produced by the organic layer when the electric field is changed has a peak brightness of at least about 20 times the brightness of light produced by the organic layer when the organic layer is optically pumped in the absence of the electric field.

19. The method of claim 1, wherein the light produced by the organic layer when the electric field is changed is coherent.

20. A device comprising:

a first electrode;

a second electrode;

an organic light emitting layer disposed between the first electrode and the second electrode; and

a first insulating layer disposed between the first electrode and the organic light emitting layer, the first insulating layer disposed to block electrical current from the organic light emitting layer,

wherein there are no electrodes between the organic light emitting layer and the first insulating layer.

21. The device of claim 20, wherein the organic light emitting layer is a small molecule organic layer.

22. The device of claim 20, wherein the organic light emitting layer comprises a first organic material doped with a second organic material.

23. The device of claim 22, wherein the second organic material is an organic small molecule material.

24. The device of claim 20, further comprising an adjustable voltage source to generate an electric field across the organic light emitting layer, the voltage source electrically connected to the first electrode and the second electrode.

25. The device of claim 20, further comprising a second insulating layer disposed to block electrical current from the organic light emitting layer.

26. The device of claim 20, further comprising a reflective layer.

27. The device of claim 20, further comprising a metal grating disposed adjacent to the first insulating layer.

28. The device of claim 20, wherein the first electrode is a grating.

29. The device of claim 20, wherein the first insulating layer comprises a polymer.

30. The device of claim 20, wherein the organic light emitting layer comprises C6 and CBP.

31. The device of claim 20, further comprising an optical pump to provide energy to the organic light emitting layer.

32. The device of claim 31 wherein the pump provides energy to the organic light emitting layer at a linear rate.

33. The device of claim 31 wherein the pump comprises an OLED.

34. The device of claim 31 wherein the pump comprises a stacked OLED.

35. The device of claim 34 wherein the pump is disposed adjacent to the first electrode.

36. The device of claim 34 further comprising a substrate, wherein the pump is disposed on a first side of the substrate and the first electrode is disposed on a second side of the substrate.

37. A method of producing light using the device of claim 20, comprising:

optically pumping the organic light emitting layer while applying an electric field across the organic layer; and

rapidly changing the electric field to produce light from the organic layer.

38. The method of claim 37 wherein rapidly changing the electric field comprises reducing the magnitude of the electric field to about 0.

39. The method of claim 37 wherein rapidly changing the electric field comprises reducing the magnitude of the electric field over a time interval of about 100 ps to about 10 ns.

40. A device comprising:

a first electrode;

a second electrode;

an optically-pumped organic stack disposed between the first electrode and the second electrode, the optically-pumped organic stack further comprising an organic light emitting layer; and

an insulating layer disposed to block electrical current from the organic light emitting layer.