Electroluminescence element and a light emitting device using the same

• US 7,737,630 B2
• Filed: 05/02/2006
• Issued: 06/15/2010
• Est. Priority Date: 08/09/2002
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Seo, Satoshi, Yamazaki, Hiroko
• Primary Examiner(s): Macchiarolo; Peter J
• Assistant Examiner(s): Raleigh; Donald L
• Application Number:
  US11/416,331
• Publication Number:
  US 20060192484A1
• Time in Patent Office: 1,505 Days
• Field of Search: 313498-512, 315/169.1, 315/169.3, 428690-691, 428/917, 438 26- 29, 438/34, 438/82, 257/40, 257/72, 257 98-100, 257642-643, 257/759, 427/58, 427/64, 427/66, 427532-535, 427/539, 445 24- 25
• US Class Current: 313/506
• CPC Class Codes: H10K 2102/3026 Top emission
• CPC Class Codes: H10K 2102/351 Thickness
• CPC Class Codes: H10K 50/18 Carrier blocking layers
• CPC Class Codes: H10K 50/805 Electrodes
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 85/311 Phthalocyanine
• CPC Class Codes: H10K 85/324 comprising aluminium, e.g. Alq3
• CPC Class Codes: H10K 85/631 Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine

Abstract

An EL element which is thicker and lower-voltage drive without doping acceptor or donor than the conventional one. An EL element in which an electroluminescent film 103 containing an organic compound which can provide electroluminescent, a floating electrode 104, an electron transport supporting layer 105 and a cathode 102 are in order laminated on an anode 101. A film thickness of the electroluminescent film 103 is on the order of a conventional film thickness (on the order of approximately 100 nm), and the electron transport supporting layer 105 may also have a film thickness on the order of the electroluminescent film 103. The EL element can be driven at lower voltage than the conventional one by introducing a hole blocking material into an electron transport supporting layer.

Claims

1. A display device comprising:

an electroluminescence element over a substrate, the electroluminescence element comprising;

an anode;

an electroluminescent film containing an organic compound capable of generating electroluminescence, over the anode;

an electron transport layer over the electroluminescent film;

a floating electrode over the electron transport layer;

an electron transport supporting layer over the floating electrode; and

a cathode over the electron transport supporting layer,

wherein the floating electrode comprises an insulating film formed in contact with the electron transporting layer and a conductive film formed in contact with the electron transport supporting layer.

2. A display device according to claim 1, wherein the electron transport supporting layer has a thickness of more than 10 nm and less than 1 μ

m.

3. A display device according to claim 1, wherein the cathode comprises a conductive film formed by sputtering.

4. A display device according to claim 1, wherein the cathode comprises a translucent conductive film formed by sputtering.

5. A display device according to claim 1, wherein at least one of the electroluminescent film and the electron transport supporting layer contains a hole blocking material, and the hole blocking material has an ionization potential of 5.8 eV or more.

6. A display device according to claim 1, wherein at least one of the electroluminescent film and the electron transport supporting layer contains a hole blocking material, and the hole blocking material is an organic compound containing a phenanthroline skeleton or a 5-coordinate metal complex having an element belonging to Group 13 of the periodic table as a central metal.

7. A display device according to claim 1, wherein the cathode comprises a conductive material having a work function of 3.5 eV or more.

8. A display device according to claim 1, wherein the electron transport supporting layer comprises an electron-transportable material having an electron mobility which is larger than a hole mobility.

9. A display device according to claim 1, wherein the floating electrode comprises a conductive material having a work function of 3.5 eV or less.

10. A display device according to claim 1, wherein the electron transport supporting layer has a film thickness in the range of 10 nm to 1 μ

m.

11. A display device comprising:

an electroluminescence element over a substrate, the electroluminescence element comprising;

a cathode;

an electron transport supporting layer over the cathode;

a floating electrode over the electron transport supporting layer;

an electron transporting layer over the floating electrode;

an electroluminescent film containing an organic compound that generates electroluminescence, over the electron transporting layer; and

an anode over the electroluminescent film,

wherein the floating electrode comprises an insulating film formed in contact with the electron transporting layer and a conductive film formed in contact with the electron transport supporting layer.

12. A display device according to claim 11, wherein the electron transport supporting layer has a thickness of more than 10 nm and less than 1 μ

m.

13. A display device according to claim 11, wherein the cathode comprises a conductive film formed by sputtering.

14. A display device according to claim 11, wherein the cathode comprises a translucent conductive film formed by sputtering.

15. A display device according to claim 11, wherein at least one of the electroluminescent film and the electron transport supporting layer contains a hole blocking material and the hole blocking material has an ionization potential of 5.8 eV or more.

16. A display device according to claim 11, wherein at least one of the electroluminescent film and the electron transport supporting layer contains a hole blocking material and the hole blocking material is an organic compound containing a phenanthroline skeleton or a 5-coordinate metal complex having an element belonging to Group 13 of the periodic table as a central metal.

17. A display device according to claim 11, wherein the cathode comprises a conductive material having a work function of 3.5 eV or more.

18. A display device according to claim 11, wherein the electron transport supporting layer comprises an electron-transportable material having an electron mobility which is larger than a hole mobility.

19. A display device according to claim 11, wherein the floating electrode comprises a conductive material having a work function of 3.5 eV or less.

20. A display device according to claim 11, wherein the electron transport supporting layer has a film thickness in the range of 10 nm to 1 μ

m.

21. An electric appliance comprising:

a display device comprising an electroluminescence element over a substrate, the electroluminescence element comprising;

an anode;

an electroluminescent film containing an organic compound capable of generating electroluminescence, over the anode;

an electron transport layer over the electroluminescent film;

a floating electrode over the electron transport layer;

an electron transport supporting layer over the floating electrode; and

a cathode over the electron transport supporting layer,

wherein the floating electrode comprises an insulating film formed in contact with the electron transporting layer and a conductive film formed in contact with the electron transport supporting layer.

22. An electronic appliance according to claim 21, wherein the electron transport supporting layer has a thickness of more than 10 nm and less than 1 μ

m.

23. An electric appliance according to claim 21, wherein the cathode comprises a conductive film formed by sputtering.

24. An electric appliance according to claim 21, wherein the cathode comprises a translucent conductive film formed by sputtering.

25. An electric appliance according to claim 21, wherein at least one of the electroluminescent film and the electron transport supporting layer contains a hole blocking material, and the hole blocking material has an ionization potential of 5.8 eV or more.

26. An electric appliance according to claim 21, wherein at least one of the electroluminescent film and the electron transport supporting layer contains a hole blocking material, and the hole blocking material is an organic compound containing a phenanthroline skeleton or 5-coordinate a metal complex having an element belonging to Group 13 of the periodic table as a central metal.

27. An electric appliance according to claim 21, wherein the cathode comprises a conductive material having a work function of 3.5 eV or more.

28. An electric appliance according to claim 21, wherein the electron transport supporting layer comprises an electron-transportable material having an electron mobility which is larger than a hole mobility.

29. An electric appliance according to claim 21, wherein the floating electrode comprises a conductive material having a work function of 3.5 eV or less.

30. An electric appliance according to claim 21, wherein the electron transport supporting layer has a film thickness in the range of 10 nm to 1 μ

m.

31. An electric appliance according to claim 21, wherein the electroluminescence element is incorporated into a light emitting device.

32. An electric appliance according to claim 21, wherein the electric appliance is one selected from the group consisting of a personal computer, a video camera, a mobile computer, a player, a digital camera, a cell phone, a portable book, and a display.

33. An electric appliance comprising:

a display device comprising an electroluminescence element over a substrate, the electroluminescence element comprising;

an electroluminescence element over a substrate, the electroluminescence element comprising;

a cathode;

an electron transport supporting layer over the cathode;

a floating electrode over the electron transport supporting layer;

an electron transporting layer over the floating electrode;

an electroluminescent film containing an organic compound that generates electroluminescence, over the electron transporting layer; and

an anode over the electroluminescent film,

wherein the floating electrode comprises an insulating film formed in contact with the electron transporting layer and a conductive film formed in contact with the electron transport supporting layer.

34. An electronic appliance according to claim 33, wherein the electron transport supporting layer has a thickness of more than 10 nm and less than 1 μ

m.

35. An electric appliance according to claim 33, wherein the cathode comprises a conductive film formed by sputtering.

36. An electric appliance according to claim 33, wherein the cathode comprises a translucent conductive film formed by sputtering.

37. An electric appliance according to claim 33, wherein at least one of the electroluminescent film and the electron transport supporting layer contains a hole blocking material and the hole blocking material has an ionization potential of 5.8 eV or more.

38. An electric appliance according to claim 33, wherein at least one of the electroluminescent film and the electron transport supporting layer contains a hole blocking material and the hole blocking material is an organic compound containing a phenanthroline skeleton or a 5-coordinate metal complex having an element belonging to Group 13 of the periodic table as a central metal.

39. An electric appliance according to claim 33, wherein the cathode comprises a conductive material having a work function of 3.5 eV or more.

40. An electric appliance according to claim 33, wherein the electron transport supporting layer comprises an electron-transportable material having an electron mobility which is larger than a hole mobility.

41. An electric appliance according to claim 33, wherein the floating electrode comprises a conductive material having a work function of 3.5 eV or less.

42. An electric appliance according to claim 33, wherein the electron transport supporting layer has a film thickness in the range of 10 nm to 1 μ

m.

43. An electric appliance according to claim 33, wherein the electroluminescence element is incorporated into a light emitting device.

44. An electric appliance according to claim 33, wherein the electric appliance is one selected from the group consisting of a personal computer, a video camera, a mobile computer, a player, a digital camera, a cell phone, a portable book, and a display.