Electric Field Light Emitting Element

• US 20070210700A1
• Filed: 07/26/2004
• Published: 09/13/2007
• Est. Priority Date: 10/02/2003
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toyota Jidoshokki
• Original Assignee: Kabushiki Kaisha Toyota Jidoshokki
• Inventors: Kato, Yoshifumi, Miura, Hiroyuki, Ishikawa, Haruyuki, Kawauchi, Hiroyasu, Takeuchi, Norihito
• Granted Patent: US 7,855,506 B2
• Time in Patent Office: Days
• US Class Current: 313/504
• CPC Class Codes: H10K 50/805 Electrodes
• CPC Class Codes: H10K 50/85 Arrangements for extracting light from the devices
• CPC Class Codes: H10K 50/88 Terminals, e.g. bond pads

Abstract

An organic EL element that is an electroluminescence element has at least an organic layer held between a pair of electrodes. At least an electrode made of material having a higher volume resistivity, of the pair of electrodes, is formed in a flat form. The organic layer is provided with a plurality of non-light emitting portions. The non-light emitting portions are provided so that a larger number of non-light emitting portions exist per unit area at a position physically closer to the position of a terminal portion at which the electrode made of material having the higher volume resistivity is connected to an external connection terminal. As a result, the level of current passing per unit area is substantially uniform at each position on the element.

Claims

1. An electroluminescence element which can emit light at least by application of a voltage to a pair of electrodes, comprising:

a light emitting portion and a non-light emitting portion, wherein

the light emitting portion and non-light emitting portion are provided for bringing the luminance distribution of the element into a desired state.

2. The electroluminescence element according to claim 1, wherein the light emitting portion and non-light emitting portion are provided so that the luminance distribution is substantially uniform as a whole.

3. The electroluminescence element according to claim 2, wherein an electrode made of material having a higher volume resistivity in the pair of electrodes is formed in a flat form, and the non-light emitting portion is provided so that the area occupied by the non-light emitting portion per unit area is greater at a position physically closer to the position of a terminal portion of the electrode made of material having the higher volume resistivity.

4. The electroluminescence element according to claim 2, wherein an electrode made of material having a higher volume resistivity in the pair of electrodes is formed in a flat form, and the light emitting portion is provided so that the area occupied by the light emitting portion per unit area is greater at a position physically further to the position of the terminal portion of the electrode made of material having the higher volume resistivity.

5. The electroluminescence element according to claim 1, wherein the light emitting portion and the non-light emitting portion are provided so that the central part of the element is brighter than other parts as a luminance distribution of the element.

6. The electroluminescence element according to claim 5, wherein the non-light emitting portion is provided so that the area occupied by the non-light emitting portion per unit area is greater in a region with a higher rate at which the luminance of the electroluminescence element emitting light is to be reduced compared to a state in which the non-light emitting portion is not provided.

7. The electroluminescence element according to claim 1, wherein the electroluminescence element is an organic electroluminescence element in which at least an organic layer which can emit light by application of a voltage is held between the pair of electrodes.

8. The electroluminescence element according to claim 7, wherein the non-light emitting portion is constructed by providing a part made of material having a work function larger than that of a material of a cathode of the pair of electrodes between the cathode and the organic layer.

9. The electroluminescence element according to claim 7, wherein the non-light emitting portion is constructed by providing a part made of material having a work function smaller than that of a material of an anode of the pair of electrodes between the anode and the organic layer.

10. The electroluminescence element according to claim 7, wherein the non-light emitting portion is constructed by modifying the organic layer to be incapable of emitting light.

11. The electroluminescence element according to claim 1, wherein the electroluminescence element is an organic electroluminescence element in which an organic layer which can emit light at least by application of a voltage is held between the pair of electrodes, and the light emitting portion is constructed by providing an electron injection layer between a cathode of the pair of electrodes and the organic layer.

12. The electroluminescence element according to claim 1, wherein the electroluminescence element is an organic electroluminescence element in which an organic layer which can emit light at least by application of a voltage is held between the pair of electrodes, and the light emitting portion is constructed by modifying a predetermined area of an anode of the pair of electrodes to have a work function larger than the work function of other areas of the anode.

13. The electroluminescence element according to claim 7, wherein the organic layer is provided on only the area which is the light emitting portion.

14. The electroluminescence element according to claim 1, wherein the electroluminescence element is an inorganic electroluminescence element.

15. The electroluminescence element according to claim 7, wherein the non-light emitting portion is constructed by providing an insulating portion on at least a part of the area between the pair of electrodes.

16. The electroluminescence element according to claim 15, wherein the electroluminescence element is formed on a substrate and constructed as a bottom emission type, and light reflection layers are provided at positions between the substrate and a transparent electrode corresponding to the insulating portions.