Electroluminescence device

• US 20050184659A1
• Filed: 01/22/2004
• Published: 08/25/2005
• Est. Priority Date: 01/29/2003
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Ibe, Takahiro
• Granted Patent: US 7,199,521 B2
• Time in Patent Office: Days
• 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. An electroluminescence device characterized in having;

a first electrode formed on 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 third electrode in contact with the second electroluminescent film, and

characterized in that 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.

6. The electroluminescence device according to any one of claims 1 to 5 characterized in that light can be taken out from the substrate side by preventing only the electrode farthest from the substrate, of the electrode selected from any of the anodes and cathodes, from transmitting light.

7. The electroluminescence device according to any one of claims 1 to 5 characterized in that light can be taken out from the opposite side of the substrate by preventing only the electrode closest to the substrate, of the electrode selected from any of the anodes and the cathodes, from transmitting light.

8. The electroluminescence device according to any one of claims 1 to 5 characterized in that light can be taken out from both of the substrate side and the opposite side of the substrate by making all of the anodes and the cathodes included in the light emitting element transmissive.

9. The electroluminescence device according to any one of claims 1 to 5 characterized in that two or more kinds of electroluminescent elements each of which emits different light are used for the plurality of electroluminescent elements.

11. The electroluminescence device according to any one of claims 1 to 5 characterized in that the anode is made of a material having work function 4.5 to 5.5 eV and the cathode is made of a material having work function 2.5 to 3.5 eV.

12. The electroluminescence device according to any one of claims 1 to 5 characterized in that the anode is consist of one of Ti, TiN, TiSi_xN_y, Ni, W, WSi_x, WN_x, WSi_xN_y, NbN, Mo, Cr, Pt, Se, Pd, Ir, or Au, and a mixture or an alloy of these, and the cathode is consist of a metal element belonging to the 1st group or the 2nd group of the periodic table and a mixture or an alloy of these.

13. An electric appliance comprises the electroluminescence device according to any one of claims 1 to 5 as a display part.

14. The electric appliance according to claim 13 characterized in that the electric appliance is a video camera, a digital camera, a goggle type display, a navigation system, an audio reproduction device, a notebook personal computer, a game machine, a portable information terminal, or an image reproduction device provided with a recording medium.

2. An electroluminescence device characterized in having;

a first electrode formed on 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 third electrode in contact with the second electroluminescent film, and

characterized in that the first electrode and the third electrode are electrically connected and function as one of an anode or a cathode and the second electrode functions as the other of the anode or the cathode.

3. An electroluminescence device characterized in having;

a first anode formed on 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 second anode in contact with the second electroluminescent film.

4. An electroluminescence device characterized in having;

a first cathode formed on a substrate;

a first electroluminescent film in contact with the first cathode;

an anode in contact with the first electroluminescent film;

a second electroluminescent film in contact with the anode; and

a second cathode in contact with the second electroluminescent film.

5. An electroluminescence device characterized in that;

a plurality of anodes and a plurality of cathodes are alternately formed over a substrate; and

electroluminescent films are formed between the respective anodes and cathodes.

10. The electroluminescence device according to claim 5 characterized in that electroluminescent films comprises at least one electroluminescent element of emitting red light, at least one electroluminescent element of emitting green light and at least one electroluminescent element of emitting blue light.