High efficiency organic light emitting devices with light directing structures

• US 5,834,893 A
• Filed: 12/23/1996
• Issued: 11/10/1998
• Est. Priority Date: 12/23/1996
• Status: Expired due to Term

• Current Assignee: The Trustees of Princeton University (Princeton University)
• Original Assignee: The Trustees of Princeton University (Princeton University)
• Inventors: Forrest, Stephen R., Bulovic, Vladimir, Burrows, Paul, Garbuzov, Dmitri Z.
• Primary Examiner(s): Patidar, Jay M.
• Application Number:
  US08/772,332
• Time in Patent Office: 687 Days
• Field of Search: 313/504, 313/506, 313/509, 313/512, 313/503, 313/498, 313/501, 428/917, 428/690, 315/169.3, 315/382.1, 434/307 R, 362/24, 362/88, 362/812, 345/30
• US Class Current: 313/506
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: H10K 2102/3026 Top emission
• CPC Class Codes: H10K 50/17 Carrier injection layers
• CPC Class Codes: H10K 50/80 Constructional details
• CPC Class Codes: H10K 50/805 Electrodes
• CPC Class Codes: H10K 50/818 Reflective anodes, e.g. ITO combined with thick metallic layers
• CPC Class Codes: H10K 50/852 comprising a resonant cavity structure, e.g. Bragg reflector pair
• CPC Class Codes: H10K 50/856 comprising reflective means
• CPC Class Codes: H10K 50/86 Arrangements for improving contrast, e.g. preventing reflection of ambient light
• CPC Class Codes: H10K 59/32 Stacked devices having two or more layers, each emitting at different wavelengths
• CPC Class Codes: H10K 59/80518 Reflective anodes, e.g. ITO combined with thick metallic layers
• CPC Class Codes: H10K 59/876 comprising a resonant cavity structure, e.g. Bragg reflector pair
• CPC Class Codes: H10K 59/878 comprising reflective means
• CPC Class Codes: H10K 59/8791 Arrangements for improving contrast, e.g. preventing reflection of ambient light
• CPC Class Codes: Y10S 428/917 Electroluminescent

Abstract

An organic light emitting device (OLED) structure having reflective surfaces is fabricated in a pit formed in a substrate. The pit has slanted reflective side walls which redirect light that is waveguided in the organic layers of the OLED to a direction substantially normal to the plane of the substrate. The reflective structure can also be formed with a planar configuration over interconnects covered with a polyimide.

Claims

1. An organic light emitting device, comprising:

a substrate with a pit having a slanted side wall formed into the top surface of the substrate,

a reflective first electrode formed on the top surface of the substrate,

a first organic layer formed on the first electrode,

a second organic layer formed on the first organic layer; and

a second electrode formed on the second organic layer,

wherein at least one of the first and second organic layers emits light upon application of a voltage between the first and second electrodes and wherein the reflective first electrode on the slanted side wall causes light to be redirected in a direction substantially perpendicular to the substrate.

2. The light emitting device of claim 1, wherein the first electrode is a cathode and the second electrode is an anode.

3. The light emitting device of claim 1, wherein:

the first organic layer is an electroluminescent electron transporting layer,

the second organic layer is a hole transporting layer, and

the first organic layer emits light upon application of the voltage between the first and second electrodes.

4. The light emitting device of claim 1,wherein:

the first organic layer is an electron transporting layer,

the second organic layer is an electroluminescent hole transporting layer, and

the second organic layer emits light upon application of the voltage between the first and second electrodes.

5. The light emitting device of claim 1, wherein:

the first organic layer is an electron transporting layer,

the second organic layer is a hole transporting layer, and

an electroluminescent layer is present between the electron transporting layer and the hole transporting layer, the electroluminescent layer emitting light upon application of the voltage between the first and second electrodes.

6. The light emitting device of claim 1, wherein the pit has a flat bottom surface with the slanted side wall forming an angle of approximately 135°

with the flat bottom surface of the pit.

7. A display including a plurality of light emitting devices in accordance with claim 1.

8. A vehicle incorporating a display including the light emitting device of claim 1.

9. A television incorporating a display including the light emitting device of claim 1.

10. A computer incorporating a display including the light emitting device of claim 1.

11. A printer incorporating the light emitting device of claim 1.

12. A screen incorporating the light emitting device of claim 1.

13. A sign incorporating the light emitting device of claim 1.

14. A telecommunications device incorporating the light emitting device of claim 1.

15. A telephone incorporating the light emitting device of claim 1.

16. The light emitting device of claim 1 wherein the pit has a flat bottom surface forming an angle of approximately 135°

with the slanted side wall.

17. The light emitting device of claim 1 wherein the pit has a semicircular cross section.

18. The light emitting device of claim 1 wherein the pit has an inverted triangular cross section.

19. An organic light emitting device, comprising:

a substrate;

a first electrode formed on a top surface of the substrate;

a first organic layer formed on the first electrode;

a second organic layer formed on the first organic layer; and

a second electrode formed on the second organic layer,

wherein the top surface of the substrate is substantially planar and the first electrode is formed between two interconnects covered with a polyimide material, the first electrode having a flat bottom surface and two side walls, each side wall forming an angle of approximately 135°

with the bottom surface of the first electrode and wherein at least one of the first and second organic layers emits light upon application of a voltage between the first and second electrodes.

20. The light emitting device of claim 19, wherein the first electrode is a cathode and the second electrode is an anode.

21. The light emitting device of claim 19, wherein:

the first organic layer is an electroluminescent electron transporting layer,

the second organic layer is a hole transporting layer, and

the first organic layer emits light upon application of the voltage between the first and second electrodes.

22. The light emitting device of claim 19 wherein:

the first organic layer is an electron transporting layer,

the second organic layer is an electroluminescent hole transporting layer, and

the second organic layer emits light upon application of the voltage between the first and second electrodes.

23. The light emitting device of claim 19 wherein:

the first organic layer is an electron transporting layer,

the second organic layer is a hole transporting layer, and

an electroluminescent layer being arranged between the electron transporting layer and the hole transporting layer the electroluminescent layer emitting light upon application of the voltage between the first and second electrodes.

24. An organic light emitting device, comprising:

a substrate with a pit having a slanted side wall formed into the top surface of the substrate,

a reflective metallic layer formed on the top surface of the substrate,

a first electrode formed on the reflective metallic layer,

a first organic layer formed on the first electrode,

a second organic layer formed on the first organic layer,

a second electrode formed on the second organic layer,

wherein at least one of the first and second organic layers emits light upon application of a voltage between the first and second electrodes and wherein the reflective metallic layer on the slanted side wall causes light to be redirected in a direction substantially perpendicular to the substrate.

25. The light emitting device of claim 24, wherein the first electrode is an anode and the second electrode is a cathode.

26. The light emitting device of claim 24, wherein:

the first organic layer is an electroluminescent hole transporting layer,

the second organic layer is an electron transporting layer, and

the first organic layer emits light upon application of the voltage between the first and second electrodes.

27. The light emitting device of claim 24, wherein:

the first organic layer is a hole transporting layer,

the second organic layer is an electroluminescent electron transporting layer, and

the second organic layer emits light upon application of the voltage between the first and second electrodes.

28. The light emitting device of claim 24, wherein:

the first organic layer is a hole transporting layer and the second organic layer is an electron transporting layer,

an electroluminescent layer is present between the hole transporting layer and the electron transporting layer, and

the electroluminescent layer emits light upon application of the voltage between the first and second electrodes.

29. The light emitting device of claim 24, wherein the pit has a flat bottom surface with the side wall forming an angle of approximately 135°

with the flat bottom surface.

30. The light emitting device of claim 24 wherein the pit has a semicircular cross section.

31. The light emitting device of claim 24 wherein the pit has an inverted triangular cross section.