Electroluminescence device

• US 7,548,022 B2
• Filed: 03/29/2007
• Issued: 06/16/2009
• Est. Priority Date: 01/29/2003
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Ibe, Takahiro
• Primary Examiner(s): Patel; Ashok
• Application Number:
  US11/729,925
• Publication Number:
  US 20070182315A1
• Time in Patent Office: 810 Days
• Field of Search: 313/498, 313/503, 313/505, 313/506, 313/512
• US Class Current: 313/506
• CPC Class Codes: H10K 2102/3026 Top emission
• CPC Class Codes: H10K 59/32 Stacked devices having two or more layers, each emitting at different wavelengths
• CPC Class Codes: H10K 59/84 Parallel electrical configurations of multiple OLEDs

Abstract

An organic EL element has excellent features as compared with other electroluminescent elements, but on the other hand, has a problem that the life of the element is not sufficiently long. In addition, since the organic EL element is expected to be applied to a mobile display and the like, it is also important to improve power efficiency. Hence, an object of the invention is to provide an element structure to realize an improvement in power efficiency and an improvement in the life of the element at the same. In the construction of an organic EL element of the invention, the first electroluminescent film 303 is sandwiched by the first anode 302 and a cathode 304, and the second electroluminescent film 305 and the second anode 306 are laminated over the cathode 304. At this time, the first anode 302 is put into contact with the second anode 306 to form a parallel circuit to decrease an electric current passing through the respective electroluminescent films.

Claims

1. A mobile telephone comprising a display part, the display part having an electroluminescence display device, the electroluminescence display device comprising:

a first electrode formed over a substrate;

a first electroluminescent film in contact with the first electrode;

a second electrode in contact with the first electroluminescent film;

a second electroluminescent film in contact with the second electrode; and

a transparent third electrode in contact with the second electroluminescent film,

wherein an electric current flow direction through the first electroluminescent film is different from an electric current flow direction through the second electroluminescent film.

2. The mobile telephone according to claim 1, wherein the number of the display part is one.

3. The mobile telephone according to claim 1, wherein electrodes comprising the first electrode and the third electrode function as one of an anode or a cathode and the second electrode functions as the other of the anode or the cathode.

4. The mobile telephone according to claim 1, wherein the electroluminescence display is an active matrix electroluminescence display.

5. The mobile telephone according to claim 1, wherein the first and third electrodes are electrically connected to each other.

6. The mobile telephone according to claim 1, wherein the third electrode covers both sides of the second electroluminescence film.

7. An electroluminescence display device comprising:

a first electrode formed over a substrate;

a first electroluminescent film in contact with the first electrode;

a second electrode in contact with the first electroluminescent film;

a second electroluminescent film in contact with the second electrode; and

a transparent third electrode in contact with the second electroluminescent film,

wherein each of the first and second electroluminescent films comprises a hole injection layer, a hole transport layer, a electroluminescent layer, an electron transport layer, and an electron injection layer, and

wherein an electric current flow direction through the first electroluminescent film is different from an electric current flow direction through the second electroluminescent film.

8. The active matrix electroluminescence display device according to claim 7, wherein electrodes comprising the first electrode and the third electrode function as one of an anode or a cathode and the second electrode functions as the other of the anode or the cathode.

9. The electroluminescence display according to claim 7, wherein the electroluminescence display is an active matrix electroluminescence display.

10. The electroluminescence display according to claim 7, wherein the first and third electrodes arc electrically connected to each other.

11. The electroluminescence display according to claim 7, wherein the third electrode covers both sides of the second electroluminescence film.

12. A mobile telephone comprising a display part, the display part having an electroluminescence display device, the electroluminescence display device comprising:

a first anode formed over a substrate;

a first electroluminescent film in contact with the first anode;

a cathode in contact with the first electroluminescent film;

a second electroluminescent film in contact with the cathode; and

a transparent second anode in contact with the second electroluminescent film,

wherein each of the first and second electroluminescent films comprises a hole injection layer, a hole transport layer, a electroluminescent layer, an electron transport layer, and an electron injection layer, and

wherein an electric current flow direction through the first electroluminescent film is different from an electric current flow direction through the second electroluminescent film.

13. The mobile telephone according to claim 12, wherein the number of the display part is one.

14. The mobile telephone according to claim 12, wherein electrodes comprising the first electrode and the third electrode function as one of an anode or a cathode and the second electrode functions as the other of the anode or the cathode.

15. The mobile telephone according to claim 12, wherein the electroluminescence display is an active matrix electroluminescence display.

16. The mobile telephone according to claim 12, wherein the first anode and the transparent second anode are electrically connected to each other.

17. The mobile telephone according to claim 12, wherein the second anode covers both sides of the second electroluminescence film.