Light emitting diode device

• US 20060049419A1
• Filed: 09/06/2005
• Published: 03/09/2006
• Est. Priority Date: 09/03/2004
• Status: Abandoned Application

• Current Assignee: Stanley Electric Company Limited
• Original Assignee: Stanley Electric Company Limited
• Inventors: Tanaka, Shinichi, Kawakami, Yasuyuki, Ogawa, Akio, Horii, Masatoshi, Jinde, Yukitoshi
• Application Number:
  US11/218,660
• Publication Number:
  US 20060049419A1
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H10K 2102/3031 Two-side emission, e.g. transparent OLEDs [TOLED]
• CPC Class Codes: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: H10K 50/85 Arrangements for extracting light from the devices
• CPC Class Codes: H10K 50/856 comprising reflective means
• CPC Class Codes: H10K 50/858 comprising refractive means, e.g. lenses

Abstract

A light emitting diode device can include a pair of opposed electrodes and a thin film multilayer structure interposed between the pair of electrodes. The device can include one or more light emitting layers each having an emission interface. In the device, there can be adjacent layers having an interfacial plane therebetween. The interfacial plane being disposed in a position where an optical path length from the emission interface to the interfacial plane is substantially equal to, or less than, the coherent length of light emitted from the emission interface. Furthermore, the difference in refractive index between the adjacent layers is substantially equal to, or less than, 0.6. This can eliminate an interference effect within the thin film multilayer structure, thereby enhancing light emitting efficiency and achieving intended light color.

Claims

1. A light emitting diode device, comprising:

a pair of electrodes; and

a thin film multilayer structure located adjacent the pair of electrodes and including at least one light emitting layer, the light emitting layer including an emission interface;

wherein

the device has adjacent layers having an interfacial plane therebetween, the interfacial plane disposed in a position such that an optical path length from the emission interface to the interfacial plane is substantially equal to, or less than, a coherent length of light emitted from the emission interface, and

a difference in refractive index between the adjacent layers is substantially equal to, or less than, 0.6.

2. The light emitting diode device according to claim 1, further comprising:

a reflecting mirror disposed in a position such that an optical path length from the emission interface to the reflecting mirror is substantially equal to, or more than, the coherent length of light emitted from the emission interface.

3. The light emitting diode device according to claim 2, wherein:

the pair of electrodes are transparent electrodes; and

the reflecting mirror is at least one of in contact with an outer surface of one of the transparent electrodes and disposed in a position spaced from an outer surface of one of the transparent electrodes.

4. The light emitting diode device according to claim 3, further comprising:

a buffer layer disposed at least one of outside one of the transparent electrodes and between one of the transparent electrodes and the reflecting mirror.

5. The light emitting diode device according to claim 4, wherein

the buffer layer is formed as at least one of a vacuum and a material selected from the group consisting of a transparent material and a gas.

6. The light emitting diode device according to claim 2, wherein

the thin film multilayer structure is composed of a plurality of light emitting units each having at least one light emitting layer, and

a charge generating layer is formed between the light emitting units.

7. The light emitting diode device according to claim 1, wherein

one of the pair of electrodes is a transparent electrode and the other electrode is a reflecting electrode disposed in a position such that an optical path length from the emission interface to the reflecting electrode is substantially equal to, or more than, the coherent length of light emitted from the emission interface.

8. The light emitting diode device according to claim 7, further comprising:

a buffer layer disposed at least one of outside the transparent electrode and between the transparent electrode and the reflecting electrode.

9. The light emitting diode device according to claim 8, wherein

the thin film multilayer structure is composed of a plurality of light emitting units each having at least one light emitting layer, and

a charge generating layer is formed between the light emitting units.

10. The light emitting diode device according to claim 1, further comprising:

at least one buffer layer, wherein

the pair of electrodes are transparent electrodes,

the at least one buffer layer is formed outside the pair of transparent electrodes, and

the coherent length of the light emitted from the emission interface is located within the at least one buffer layer.

11. The light emitting diode device according to claim 10, wherein,

the thin film multilayer structure is composed of a plurality of light emitting units each having at least one light emitting layer, and

a charge generating layer is formed between the light emitting units.

12. The light emitting diode device according to claim 1, wherein the pair of electrodes are opposed to each other, and the thin film multilayer structure is interposed between the pair of electrodes.

13. A light emitting diode device, comprising:

at least one electrode;

a thin film multilayer structure located adjacent the at least one electrode and including at least one light emission interface;

a mirror surface spaced from the emission interface such that an optical path length from the light emission interface to the mirror surface is substantially equal to, or more than, a coherent length of light emitted from the emission interface, and a difference in refractive index is substantially equal to, or less than, 0.6, for all adjacent layers between the emission interface and the mirror surface.

14. The light emitting diode device according to claim 13, wherein the mirror surface is formed at an interfacial plane located between adjacent layers of the multilayer structure.

15. The light emitting diode device according to claim 13, wherein

the at least one electrode is a transparent electrode, and

the mirror is at least one of in contact with an outer surface of the at least one transparent electrode and disposed in a position spaced from an outer surface of the at least one transparent electrode.

16. The light emitting diode device according to claim 15, further comprising:

a buffer layer disposed at least one of outside of the at least one transparent electrode and between the at least one transparent electrode and the mirror.

17. The light emitting diode device according to claim 16, wherein

the buffer layer is formed as at least one of a vacuum and a material selected from the group consisting of a transparent material and a gas.

18. The light emitting diode device according to claim 13, wherein

the thin film multilayer structure is composed of a plurality of light emitting units each having at least one light emitting layer, and

a charge generating layer is formed between the light emitting units.

19. The light emitting diode device according to claim 13, wherein

the at least one electrode includes a transparent electrode and a reflecting electrode, the reflecting electrode disposed in a position such that an optical path length from the emission interface to the reflecting electrode is substantially equal to, or more than, the coherent length of light emitted from the emission interface;

a buffer layer is disposed at least one of outside the transparent electrode and between the transparent electrode and the reflecting electrode.

20. The light emitting diode device according to claim 19, wherein

the thin film multilayer structure is composed of a plurality of light emitting units each having at least one light emitting layer;

and

a charge generating layer is formed between the light emitting units.