Electroluminescent device having improved light output

• US 7,911,133 B2
• Filed: 05/10/2007
• Issued: 03/22/2011
• Est. Priority Date: 05/10/2007
• Status: Active Grant

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Inventors: Preuss, Donald R., Tyan, Yuan-Sheng, Cushman, Thomas R., Kesel, Raymond A., Farruggia, Giuseppe
• Primary Examiner(s): Macchiarolo; Peter J
• Assistant Examiner(s): Walford; Natalie K
• Application Number:
  US11/746,820
• Publication Number:
  US 20080278067A1
• Time in Patent Office: 1,412 Days
• Field of Search: None
• US Class Current: 313/506
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: H10K 2102/102 comprising tin oxides, e.g. fluorine-doped SnO2
• CPC Class Codes: H10K 2102/331 Nanoparticles used in non-emissive layers, e.g. in packaging layer
• CPC Class Codes: H10K 2102/351 Thickness
• CPC Class Codes: H10K 50/18 Carrier blocking layers
• CPC Class Codes: H10K 50/828 Transparent cathodes, e.g. comprising thin metal layers
• CPC Class Codes: H10K 50/854 comprising scattering means

Abstract

An OLED device including a transparent substrate having a first surface and a second surface, a transparent electrode layer disposed over the first surface of the substrate, a short reduction layer disposed over the transparent electrode layer, an organic light-emitting element disposed over the short reduction layer and including at least one light-emitting layer and a charge injection layer disposed over the light emitting layer, a reflective electrode layer disposed over the charge injection layer and a light extraction enhancement structure disposed over the first or second surface of the substrate; wherein the short reduction layer is a transparent film having a through-thickness resistivity of 10⁻⁹ to 10² ohm-cm²; wherein the reflective electrode layer includes Ag or Ag alloy containing more than 80% of Ag; and the total device size is larger than 10 times the substrate thickness.

Claims

1. An OLED device comprising in sequence:

a transparent substrate having a first surface and a second surface;

a light extraction enhancement structure in direct contact with the first or second surface of the substrate;

a transparent electrode layer either in direct contact with the first surface of the substrate or the light extraction enhancement structure located on the first side of the substrate;

a short reduction layer in direct contact with the transparent electrode layer wherein the short reduction layer is a transparent film having a through-thickness resistivity of 10<sup>−

9</sup> to 10² ohm-cm²;

an organic light-emitting element disposed over the short reduction layer and including at least one light-emitting layer and a charge injection layer disposed over the light emitting layer;

a reflective electrode layer disposed over the charge injection layer wherein the reflective electrode layer includes Ag or Ag alloy containing more than 80% of Ag; and

the total device size is larger than 10 times the substrate thickness.

2. The OLED device of claim 1 wherein the short reduction layer includes a material selected from indium oxide, zinc oxide, tin oxide, molybdenum oxide, vanadium oxide, antimony oxide, bismuth oxide, rhenium oxide, tantalum oxide, tungsten oxide, niobium oxide, or nickel oxide.

3. The OLED device of claim 1 wherein the short reduction layer includes a mixture of at least two materials selected from indium oxide, zinc oxide, tin oxide, molybdenum oxide, vanadium oxide, antimony oxide, bismuth oxide, rhenium oxide, tantalum oxide, tungsten oxide, niobium oxide, or nickel oxide.

4. The OLED device of claim 1 wherein the short reduction layer includes a mixture of an electrically insulating oxide, fluoride, nitride, or sulfide material and at least one material selected from indium oxide, zinc oxide, tin oxide, molybdenum oxide, vanadium oxide, antimony oxide, bismuth oxide, rhenium oxide, tantalum oxide, tungsten oxide, niobium oxide, or nickel oxide.

5. The OLED device of claim 4 wherein the short reduction layer includes a mixture of zinc sulfide with indium-tin oxide, indium oxide, or tin oxide.

6. The OLED device of claim 1 wherein the reflective electrode is a cathode and the charge injection layer is an electron injection layer.

7. The OLED device of claim 1 wherein the reflective electrode is an anode and the charge injection layer is a hole injection layer.

8. The OLED device of claim 1 wherein the light extraction enhancement structure is a scattering layer.

9. The OLED device of claim 8 wherein the scattering layer includes particles or voids dispersed in a matrix having different optical index from the particles or the voids.

10. The OLED device of claim 8 wherein the scattering layer is on a separate support and then laminated to the substrate.

11. The OLED device of claim 8 where in the scattering layer includes a coating of high index particles with voids between the particles on the substrate surface.

12. The OLED device of claim 11 wherein the high index particles are selected from inorganic materials including Titanium Oxide, Zirconium oxide, Niobium Oxide, Tantalum Oxide, Zinc Oxide, Tin Oxide, or Zinc Sulfide.

13. The OLED device of claim 11 wherein the high index particles are irregular in shape and have a maximum linear extent predominantly between 300 nm to about 2,000 nm.

14. The OLED device of claim 1 wherein the OLED device includes one or more serially connected segments.

15. The OLED device of claim 1 wherein the OLED device has a stacked structure.