Light-emitting device and method of manufacturing the same

• US 6,580,213 B2
• Filed: 01/30/2001
• Issued: 06/17/2003
• Est. Priority Date: 01/31/2000
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): NGO, HOANG X
• Application Number:
  US09/771,927
• Publication Number:
  US 20010031509A1
• Time in Patent Office: 868 Days
• Field of Search: 313/504, 313/506, 428/690, 428/917
• US Class Current: 313/506
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 50/18 Carrier blocking layers
• CPC Class Codes: H10K 50/181 Electron blocking layers
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/131 Interconnections, e.g. wiring lines or terminals
• CPC Class Codes: Y10S 428/917 Electroluminescent
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/31819 Next to cellulosic

Abstract

The present invention has an object to provide a method of raising a re-coupling efficiency of carriers in an EL element to thereby provide a light-emitting device having high emission efficiency. The method is that the electron trap region 106 and the hole trap region 107 are formed in the interior of the emission layer 103. The electron trap region 106 here is a region that has the action of enclosing within the emission layer an electrons that is transferred at the lowest unoccupied molecular orbit (LUMO) level of the emission layer 103. In addition, the hole trap region 107 is a region that has the action of enclosing within the emission layer a hole that is transferred at the highest occupied molecular orbit (HOMO) level of the emission layer 103.

Claims

1. A light-emitting device having a luminous element that is composed of a cathode, an anode, and an emission layer, wherein an electron trap region or a hole trap region is provided in the interior of said emission layer,

wherein at least one of the electron trap region and the hole trap region is a cluster of organic substances.

5. A light-emitting device according to claim 1, wherein said emissive layer includes an electron trap region that has a LUMO level that is lower than the LUMO level of said emission layer.

6. A light-emitting device according to claim 1, wherein said emissive layer includes a hole trap region that has a HOMO level that is higher than the HOMO level of said emission layer.

15. A light-emitting device according to claim 1, wherein the device is incorporated in an electrical equipment as a display portion.

18. A light-emitting device according to claim 1, wherein the device is incorporated in an electrical equipment as a light source.

2. A light-emitting device having a luminous element that is composed of a cathode, an anode, and an emission layer, wherein an electron trap region, a hole trap region, an electron prevention region, or a hole prevention region is provided in the interior of said emission layer,

wherein at least one of the electron prevention region and the hole prevention region is a cluster of organic substances.

3. A light-emitting device according to claim 2, wherein said emissive layer includes an electron prevention region that has a LUMO level that is higher than the LUMO level of said emission layer.

4. A light-emitting device according to claim 2, wherein said emissive layer includes a hole prevention region that has a HOMO level that is lower than the HOMO level of said emission layer.

13. A light-emitting device according to claim 2, wherein said emissive layer includes an electron trap region that has a LUMO level that is lower than the LUMO level of said emission layer.

14. A light-emitting device according to claim 2, wherein said emissive layer includes a hole trap region that has a HOMO level that is higher than the HOMO level of said emission layer.

16. A light-emitting device according to claim 2, wherein the device is incorporated in an electrical equipment as a display portion.

19. A light-emitting device according to claim 2, wherein the device is incorporated in an electrical equipment as a light source.

7. A light-emitting device having a luminous element that is composed of a cathode, an anode, and an emission layer, wherein a region that shows a LUMO level that is lower than the LUMO level of said emission layer or a region that shows a HOMO level that is higher than the HOMO level of said emission layer is provided in the interior of said emission layer,

wherein at least one of the region that shows a LUMO level that is lower than the LUMO level of the emission layer and the region that shows a HOMO level that is higher than the HOMO level of the emission layer is a cluster of organic substances.

17. A light-emitting device according to claim 7, wherein the device is incorporated in an electrical equipment as a display portion.

20. A light-emitting device according to claim 7, wherein the device is incorporated in an electrical equipment as a light source.

8. A light-emitting device having a luminous element that is composed of a cathode, an anode, and an emission layer, wherein a region that shows a LUMO level that is lower than the LUMO level of said emission layer, a region that shows a HOMO level that is higher than the HOMO level of said emission layer, a region that shows a LUMO level that is higher than the LUMO level of said emission layer, or a region that shows a HOMO level that is lower than the HOMO level of said emission layer is provided in the interior of said emission layer,

wherein at least one of the region that shows a LUMO level that is higher than the LUMO level of the emission layer and the region that shows a HOMO level that is lower than the HOMO level of the emission layer is a cluster of organic substances.

9. A light-emitting device according to claim 8, wherein the device is incorporated in an electrical equipment as a display portion.

10. A light-emitting device according to claim 8, wherein the device is incorporated in an electrical equipment as a light source.

11. A light-emitting device having a luminous element, said luminous element comprising:

an anode over a substrate;

a first emission layer over said anode;

an electron trap region adjacent to said first emission layer;

a second emission layer adjacent to said electron trap region;

a hole trap region adjacent to said second emission layer;

a third emission layer adjacent to said hole trap region; and

a cathode over said third emission layer,

wherein said electron trap region has a LUMO level that is lower than the LUMO level of said first and second and third emission layers,

wherein said hole trap region has a HOMO level that is higher than the HOMO level of said first and second and third emission layers.

12. A light-emitting device having a luminous element, said luminous element comprising:

a cathode over a substrate;

a first emission layer over said cathode;

an electron trap region adjacent to said first emission layer;

a second emission layer adjacent to said electron trap region;

a hole trap region adjacent to said second emission layer;

a third emission layer adjacent to said hole trap region; and

an anode over said third emission layer,

wherein said electron trap region has a LUMO level that is lower than the LUMO level of said first and second and third emission layers,

wherein said hole trap region has a HOMO level that is higher than the HOMO level of said first and second and third emission layers.