Organic electroluminescent device

• US 20040150333A1
• Filed: 07/24/2003
• Published: 08/05/2004
• Est. Priority Date: 08/09/2002
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Tsutsui, Tetsuo
• Granted Patent: US 7,239,081 B2
• Time in Patent Office: Days
• US Class Current: 313/512
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• 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 50/19 Tandem OLEDs
• CPC Class Codes: H10K 71/841 Applying alternating current [AC] during manufacturing or treatment
• CPC Class Codes: Y10S 428/917 Electroluminescent

Abstract

An organic EL device that has good yields and high reliability as well as high current efficiency is provided by introducing the new concept to the conventional organic EL device structure. An EL device comprising a first electrode 101, a second electrode 102, an electroluminescent layer 103, conductive particles 104, wherein conductive particles 104 are dispersed in the EL layer 103, is used. Current efficiency will be increased since conductive particles serve as the conventional charge generation layer. In addition, fabricating processes will become simplified and fabricating costs will be reduced because the conductive particles and the EL layer can be formed simultaneously.

Claims

1. An organic electroluminescent device comprising:

a first electrode;

a second electrode; and

an electroluminescent layer between the first electrode and the second electrode, the electroluminescent layer containing an organic compound that emits light by an application of a voltage,

wherein conductive particles are dispersed in the electroluminescent layer.

2. An organic electroluminescent device according to claim 1, further comprising:

an insulating layer disposed between the first electrode and the electroluminescent layer for preventing a carrier injection from the first electrode to the electroluminescent layer; and

an insulating layer disposed between the second electrode and the electroluminescent layer for preventing a carrier injection from the second electrode to the electroluminescent layer.

3. An organic electroluminescent device according to claim 1, further comprising:

an insulating layer disposed between the first electrode and the electroluminescent layer; and

an insulating layer disposed between the second electrode and the electroluminescent layer;

wherein the organic electroluminescent device is operated by an alternating current bias.

4. An organic electroluminescent device according to claim 1, wherein the electroluminescent layer comprises a bipolar characteristics.

5. An organic electroluminescent device according to claim 1, wherein the electroluminescent layer comprises a bipolar mixed layer in which an organic compound having an electron transporting characteristics and an organic compound having a hole transporting characteristics are mixed.

6. An organic electroluminescent device according to claim 1, wherein the electroluminescent layer contains a polymeric compound having at least one of a π

-conjugate system and a σ

-conjugate system and having a bipolar characteristics.

7. An organic electroluminescent device according to claim 1, wherein the conductive particles contain a material having a conductivity equal to or greater than 10⁻

10 S/m.

8. An organic electroluminescent device according to claim 1, wherein the conductive particles comprise metal particles having an average diameter between 2 and 50 nm.

9. An organic electroluminescent device according to claim 8, wherein the metal particles comprise at least one selected from the group consisting of gold, silver, and platinum.

10. An organic electroluminescent device according to claim 8, wherein the metal particles are covered with an organic compound.

11. An organic electroluminescent device according to claim 1, wherein the conductive particles comprise inorganic semiconductor particles having an average diameter between 2 and 50 nm.

12. An organic electroluminescent device according to claim 11, wherein the inorganic semiconductor particles comprise at least one selected from the group consisting of cadmium sulfide, selenium sulfide, zinc oxide, zinc sulfide, copper iodide, and an indium tin oxide.

13. An organic electroluminescent device according to claim 11, wherein the inorganic semiconductor particles covered with an organic compound.

14. An organic electroluminescent device according to claim 1, wherein the conductive particles comprise at least one selected from the group consisting of carbon particles, carbon particles that have undergone a surface treatment by use of a surfactant, carbon nanotubes, and fullerenes.