Serially-connected organic light emitting diode stack having conductors sandwiching each light emitting layer

• US 6,337,492 B1
• Filed: 05/08/1998
• Issued: 01/08/2002
• Est. Priority Date: 07/11/1997
• Status: Expired due to Term

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: eMagin Corporation (Samsung Electronics Co. Ltd.)
• Inventors: Howard, Webster E., Jones, Gary W.
• Primary Examiner(s): Lee, Eddie
• Assistant Examiner(s): Baumeister, Bradley W.
• Application Number:
  US09/074,423
• Time in Patent Office: 1,341 Days
• Field of Search: 257/40, 257/88, 257/89, 313/504, 313/505
• US Class Current: 257/40
• CPC Class Codes: H10K 2101/80 Composition varying spatially, e.g. having a spatial gradient
• CPC Class Codes: H10K 50/19 Tandem OLEDs
• CPC Class Codes: H10K 59/32 Stacked devices having two or more layers, each emitting at different wavelengths
• CPC Class Codes: H10K 59/86 Series electrical configurations of multiple OLEDs

Abstract

The light emitting device comprises a plurality of stacked organic light emitting devices. The plurality of organic light emitting devices are arranged in a stack. The light emitting device further includes a controller for controlling operation of each of the plurality of organic light emitting devices in the stack. The controller supplies the same current to each of the organic light emitting devices in the stack. The controller simultaneously supplies the same current to each of the plurality of the organic light emitting devices.

Claims

1. A light emitting device comprising:

a substrate having a surface;

a stack of organic light emitting devices comprising at least a first organic light emitting device and an uppermost organic light emitting device, wherein each organic light emitting device comprises;

a first conductor layer having an upper and a lower surface,

an OLED layer comprising at least one organic layer and having an upper and a lower surface, wherein the lower surface of the OLED layer is in contact with the upper surface of the first conductor layer, and

a second conductor layer having an upper surface and a lower surface, wherein the lower surface of the second conductor layer is in contact with the upper surface of the OLED layer,

wherein the lower surface of the first conductor layer of the first organic light emitting device is in contact with the surface of the substrate, and wherein the lower surface of the first conductor of each subsequent organic light emitting device is in contact with the upper surface of the second conductor of an organic light emitting device directly below it in the stack; and

a direct current source for supplying current to the stack of organic light emitting devices wherein the current source applies a voltage between the first conductor layer of the first organic light emitting device and the second conductor layer of the uppermost organic light emitting device with the electrical circuit being completed by an electrical current flowing directly through the stack.

2. The light emitting device according to claim 1 wherein the first conductor layer of each subsequent organic light emitting device and the second conductor layer of an organic light emitting device directly below it in the stack are formed as a single layer.

3. The light emitting device according to claim 1 wherein the first conductor layers comprise one or more materials independently selected from a mixture of indium oxide with tin oxide, indium tin oxide, 90 percent Mg with 10 percent Ag, LiF over Al, ITO on Al with 4 percent Cu, indium zinc oxide, and molybdenum.

4. The light emitting device according to claim 1 wherein the first conductor layers comprise one or more materials independently selected from a mixture of indium oxide with tin oxide, and indium tin oxide.

5. The light emitting device according to claim 1 wherein the second conductor layers comprise a material independently selected from a metal, diamond-like carbon, ITO, SiC and CuPc.

6. The light emitting device according to claim 1 wherein the second conductor layers comprise a metal.

7. The light emitting device according to claim 1 wherein the second conductor layers comprise one or more metals independently selected from a Mg/Ag alloy, a Al/Cu/Ti alloy, molybdenum, cobalt, nickel and indium.

8. The light emitting device according to claim 1 wherein the second conductor layers have a thickness of 1 to 150 Angstroms.

9. The light emitting device according to claim 1 wherein the second conductor layers are patterned and have a thickness of 50 to 150 Angstroms.

10. The light emitting device according to claim 1 wherein the second conductor layers comprise a layer of a material selected from CuPc or Alq.

11. The light emitting device according to claim 1 wherein the second conductor layers comprise a discontinuous film.

12. The light emitting device according to claim 11 wherein the discontinuous film has a thickness of 1 to 2 Angstroms.

13. The light emitting device according to claim 1 wherein the first conductor layer of the uppermost organic light emitting device and the second conductor layer of the organic light emitting device below it in the stack together comprise a single semiconductor layer having a concentration gradient of a material forming a first conductor portion and a material forming a second conductor portion, wherein the concentration of the material forming the second conductor portion is highest near the OLED layer of the organic light emitting device lower in the stack and the concentration of the material forming the first conductor portion is highest near the OLED layer of the organic light emitting device higher in the stack.

14. The light emitting device according to claim 1 wherein the OLED layers comprise a hole transport layer, at least one light emitting layer, and an electron transport layer.

15. The light emitting device according to claim 1 wherein the substrate comprises an active matrix substrate and the first conductor layer of the first organic light emitting device comprises electrode pads.

16. The light emitting device according to claim 1 wherein the stack consists of a first organic light emitting device, a second organic light emitting device, and an uppermost organic light emitting device.

17. The light emitting device according to claim 16 wherein each of the second conductor layers of the organic light emitting devices has a thickness, wherein the thickness of the second conductor layer of the uppermost organic light emitting device is greater than the thickness of the second conductor layers of the first and second organic light emitting devices.

18. The light emitting device according to claim 1 wherein each of the organic light emitting devices emits a light of a different color.

19. The light emitting device according to claim 1 wherein the second conductor layer of the uppermost organic light emitting device comprises a metal, and the second conductor layers of all other organic light emitting devices in the stack comprise a bilayer of an electron injector and hole injector.