OLED device having improved light output

• US 7,602,118 B2
• Filed: 02/24/2005
• Issued: 10/13/2009
• Est. Priority Date: 02/24/2005
• Status: Active Grant

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Eastman Kodak Company
• Inventors: Preuss, Donald R., Tyan, Yuan-Sheng, Cok, Ronald S.
• Primary Examiner(s): Patel; Nimeshkumar D.
• Assistant Examiner(s): Hines; Anne M
• Application Number:
  US11/065,082
• Publication Number:
  US 20060186802A1
• Time in Patent Office: 1,692 Days
• Field of Search: 313500-512, 313/489, 428/690
• US Class Current: 313/506
• CPC Class Codes: H10K 50/805 Electrodes
• CPC Class Codes: H10K 50/841 Self-supporting sealing arrangements
• CPC Class Codes: H10K 50/854 comprising scattering means
• CPC Class Codes: H10K 50/858 comprising refractive means, e.g. lenses

Abstract

An organic light-emitting diode (OLED) device, comprising: a substrate; an OLED comprising first and second electrodes and one or more layers of organic light-emitting material formed between the electrodes, wherein at least one electrode comprises a transparent electrode, the transparent electrode and layer(s) of organic light-emitting material having a first refractive index range; and an encapsulating cover; wherein at least one of the substrate or cover comprises a transparent substrate or cover having a second refractive index and through which light from the OLED is emitted; and further comprising a light scattering layer located between the substrate and cover, and a transparent low-index element having a third refractive index lower than each of the first refractive index range and second refractive index and located between the scattering layer and the transparent substrate or cover.

Claims

1. An organic light-emitting diode (OLED) device, comprising:

a substrate;

an OLED comprising a first reflective electrode and a second transparent electrodes and one or more layer(s) of organic light-emitting material formed between the first reflective and second transparent electrodes, the first reflective electrode formed between the substrate and the one or more layer(s) of organic light-emitting material and the second transparent electrode and the layer(s) of organic light-emitting material having a first refractive index range; and

a separate transparent encapsulating cover having a second refractive index and through which light from the OLED is emitted;

further comprising a light scattering layer located between the substrate and cover external to the OLED, and a transparent low-index element having a third refractive index lower than each of the first refractive index range and second refractive index and located between the scattering layer and adjacent to and in contact with the transparent cover through which light from the OLED is emitted; and

further comprising raised areas extending through the OLED and above the surface of the light-emitting area of the OLED and in contact with the cover.

2. The OLED device of claim 1, wherein the scattering layer is located between an electrode and the cover.

3. The OLED device of claim 1, wherein the scattering layer is adjacent to and in contact with an electrode.

4. The OLED device of claim 1, wherein the cover is a transparent cover through which light from the OLED is emitted, and wherein the transparent low-index element is adjacent to and in contact with the cover.

5. The OLED device of claim 4, wherein the transparent low-index element comprises a solid layer, void or gap between the OLED and the cover.

6. The OLED device of claim 5, wherein the transparent low-index element comprises a gap filled with air or an inert gas.

7. The OLED device of claim 4, wherein the OLED comprises a first reflective electrode formed over the substrate, and a transparent second electrode formed over the layer(s) of organic light-emitting material, and the scattering layer is located over the transparent electrode.

8. The OLED device of claim 7, further comprising a protective layer formed between the second transparent electrode and the scattering layer, the protective layer having a refractive index in the first refractive index range.

9. The OLED device of claim 1, wherein the transparent low-index element comprises a solid layer of optically transparent material.

10. The OLED device of claim 1, wherein the transparent low-index element comprises a void or gap filled with an optically transparent gas or liquid material.

11. The OLED device of claim 1, wherein the light scattering layer is an electrode.

12. The OLED) device of claim 1, wherein at least one electrode comprise multiple layers.

13. The OLED) device of claim 12, wherein the electrode comprising multiple layers includes a transparent layer and a reflective layer.

14. The OLED device of claim 13, wherein the light scattering layer is located between the transparent layer and the reflective layer of the multiple layer electrode.

15. The OLED device of claim 13, wherein the light scattering layer is the reflective layer of the multiple layer electrode.

16. The OLED device of claim 1, wherein the transparent layer of the multiple layer electrode is electrically conductive.

17. The OLED device of claim 1, wherein the transparent low-index element is greater than 1 micrometer thick.

18. The OLED device of claim 1, wherein the OLED is an active-matrix device, and the raised areas comprise patterned insulative layer materials.

19. The OLED device of claim 1, wherein the OLED is a display device.

20. The OLED device of claim 1, wherein the scattering layer includes at least one material having a refractive index equal to or greater than the first refractive index range.

21. The OLED device of claim 1, wherein the scattering layer includes a matrix material with a lower index of refraction and a scattering material with a higher index of refraction.

22. The OLED device of claim 1, wherein the scattering layer includes a matrix material with a higher index of refraction and a scattering material with a lower index of refraction.

23. The OLED device of claim 1, wherein the scattering layer includes polymers, electrically conductive polymers, silicon dioxide, silicon nitride, titanium dioxide, or resin.

24. The OLED device of claim 1, wherein the scattering layer is electrically conductive.

25. The OLED device of claim 1, wherein the transparent substrate or cover has an anti-reflection layer applied to one or both sides thereof.

26. An organic light-emitting diode (OLED) device, comprising:

a substrate;

an OLED comprising a first reflective electrode and a second transparent electrodes and one or more layer(s) of organic light-emitting material formed between the first reflective and second transparent electrodes, the first reflective electrode formed between the substrate and the one or more layer(s) of organic light emitting material and the second transparent electrode and the layer(s) of organic light-emitting material having a first refractive index range; and

a separate transparent encapsulating cover having a second refractive index and through which light from the OLED is emitted;

further comprising a light scattering layer located between the substrate and cover external to the OLED, and a transparent low-index element having a third refractive index lower than each of the first refractive index range and second refractive index and located between the scattering layer and the transparent cover through which light from the OLED is emitted; and

further comprising a short-reduction layer having a through-thickness resistivity between 10<sup>−

7</sup> ohm-cm² to 10³ ohm-cm² between the first electrodes and the one or more layers of organic light-emitting materials or between the second electrode and the one or more layers of organic light-emitting materials.