Light extraction film with nanoparticle coatings

• US 8,249,409 B2
• Filed: 04/28/2011
• Issued: 08/21/2012
• Est. Priority Date: 12/17/2008
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Zhang, Jun-Ying, Baran, Jimmie R. Jr., Smith, Terry L., Schultz, William J., Kolb, William Blake, Patnaude, Cheryl A., Lamansky, Sergey A., Nelson, Brian K., Jing, Naiyong, Kolb, Brant U.
• Primary Examiner(s): Lepisto, Ryan
• Assistant Examiner(s): TAVLYKAEV, ROBERT FUATOVICH
• Application Number:
  US13/096,000
• Publication Number:
  US 20110200293A1
• Time in Patent Office: 481 Days
• Field of Search: 385/131, 257/40, 257/629, 257/635, 257/642, 257/E51.021, 257/E51.001, 257/E51.002, 257/E51.018, 257/E51.019, 257/E33.074, 313/505, 313/504, 313/509, 313/512
• US Class Current: 385/131
• 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: G02B 6/0035 provided on the surface of the light guide or in the bulk of it
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: H10K 2102/331 Nanoparticles used in non-emissive layers, e.g. in packaging layer
• CPC Class Codes: H10K 50/854 comprising scattering means
• CPC Class Codes: H10K 50/858 comprising refractive means, e.g. lenses

Abstract

A multifunctional optical film for enhancing light extraction includes a flexible substrate, a structured layer having nanoparticles of different sizes, and a backfill layer. The structured layer effectively uses microreplicated diffractive or scattering nanostructures located near enough to the light generation region to enable extraction of an evanescent wave from an organic light emitting diode (OLED) device. The backfill layer has a material having an index of refraction different from the index of refraction of the structured layer. The backfill layer also provides a planarizing layer over the structured layer in order to conform the light extraction film to a layer of an OLED display device. The film may have additional layers added to or incorporated within it to an emissive surface in order to effect additional functionalities beyond improvement of light extraction efficiency.

Claims

1. A multifunctional optical film for enhancing light extraction from a self-emissive light source having a surface that outputs light, comprising:

a flexible substrate substantially transmissive to light emitted by the self-emissive light source;

a structured layer of extraction elements having a first index of refraction,

wherein the extraction elements comprise nanoparticles disposed in a surface layer manner on the substrate, and the extraction elements form a non-planar surface of the structured layer, and

wherein the nanoparticles comprise first nanoparticles having diameters within a first range and second nanoparticles added to the first nanoparticles and having diameters in a second range less than and non-overlapping with the first range;

a backfill layer comprising a material having a second index of refraction different from

the first index of refraction, wherein the backfill layer forms a planarizing layer over the nanoparticles on the non-planar surface of the structured layer, forming a planar surface on a side of the backfill layer opposite the nanoparticles,

wherein a substantial portion of the extraction elements are in optical communication with the light output surface of the self-emissive light source when the planar surface of the backfill layer is located against the light output surface of the self-emissive light source,

wherein the structured layer and backfill layer are in sufficient proximity to the light output surface of the self-emissive light source when the planar surface of the backfill layer is located against the light output surface of the self-emissive light source in order to at least partially enhance the extraction of light from the light output surface, and

wherein the first range of diameters is 60 nm to 10 microns, and the second range of diameters is 3 nm to 40 nm; and

a coating applied to the substrate and having at least one of the following functions;

color filtering;

color shifting;

polarization modification;

antireflection;

light redirection;

diffusion;

or optical rotation.

2. A multifunctional optical film for enhancing light extraction from a self-emissive light source having a surface that outputs light, comprising:

a flexible substrate substantially transmissive to light emitted by the self-emissive light source;

a structured layer of extraction elements having a first index of refraction,

wherein the extraction elements comprise nanoparticles disposed in a surface layer manner on the substrate, and the extraction elements form a non-planar surface of the structured layer, and

wherein the nanoparticles comprise first nanoparticles having diameters within a first range and second nanoparticles added to the first nanoparticles and having diameters in a second range less than and non-overlapping with the first range;

a backfill layer comprising a material having a second index of refraction different from

the first index of refraction, wherein the backfill layer forms a planarizing layer over the nanoparticles on the non-planar surface of the structured layer, forming a planar surface on a side of the backfill layer opposite the nanoparticles,

wherein a substantial portion of the extraction elements are in optical communication with the light output surface of the self-emissive light source when the planar surface of the backfill layer is located against the light output surface of the self-emissive light source,

wherein the structured layer and backfill layer are in sufficient proximity to the light output surface of the self-emissive light source when the planar surface of the backfill layer is located against the light output surface of the self-emissive light source in order to at least partially enhance the extraction of light from the light output surface, and

wherein the first range of diameters is 60 nm to 10 microns, and the second range of diameters is 3 nm to 40 nm; and

a coating applied to the substrate and having at least one of the following functions;

antiabrasion;

antismudge;

hydrophobicity;

or hydrophilicity.

3. A multifunctional optical film for enhancing light extraction from a self-emissive light source having a surface that outputs light, comprising:

a flexible substrate substantially transmissive to light emitted by the self-emissive light source;

a structured layer of extraction elements having a first index of refraction,

wherein the extraction elements comprise nanoparticles disposed in a surface layer manner on the substrate, and the extraction elements form a non-planar surface of the structured layer, and

wherein the nanoparticles comprise first nanoparticles having diameters within a first range and second nanoparticles added to the first nanoparticles and having diameters in a second range less than and non-overlapping with the first range; and

a backfill layer comprising a material having a second index of refraction different from

the first index of refraction, wherein the backfill layer forms a planarizing layer over the nanoparticles on the non-planar surface of the structured layer, forming a planar surface on a side of the backfill layer opposite the nanoparticles,

wherein a substantial portion of the extraction elements are in optical communication with the light output surface of the self-emissive light source when the planar surface of the backfill layer is located against the light output surface of the self-emissive light source,

wherein the structured layer and backfill layer are in sufficient proximity to the light output surface of the self-emissive light source when the planar surface of the backfill layer is located against the light output surface of the self-emissive light source in order to at least partially enhance the extraction of light from the light output surface,

wherein the first range of diameters is 60 nm to 10 microns, and the second range of diameters is 3 nm to 40 nm, and

wherein the substrate comprises one of the following;

a polymer film;

or a barrier material.

4. A multifunctional optical film for enhancing light extraction from a self-emissive light source having a surface that outputs light, comprising:

a flexible substrate substantially transmissive to light emitted by the self-emissive light source;

a structured layer of extraction elements having a first index of refraction,

wherein the extraction elements comprise nanoparticles disposed in a surface layer manner on the substrate, and the extraction elements form a non-planar surface of the structured layer, and

wherein the nanoparticles comprise first nanoparticles having diameters within a first range and second nanoparticles added to the first nanoparticles and having diameters in a second range less than and non-overlapping with the first range; and

a backfill layer comprising a material having a second index of refraction different from

the first index of refraction, wherein the backfill layer forms a planarizing layer over the nanoparticles on the non-planar surface of the structured layer, forming a planar surface on a side of the backfill layer opposite the nanoparticles,

wherein a substantial portion of the extraction elements are in optical communication with the light output surface of the self-emissive light source when the planar surface of the backfill layer is located against the light output surface of the self-emissive light source,

wherein the structured layer and backfill layer are in sufficient proximity to the light output surface of the self-emissive light source when the planar surface of the backfill layer is located against the light output surface of the self-emissive light source in order to at least partially enhance the extraction of light from the light output surface,

wherein the first range of diameters is 60 nm to 10 microns, and the second range of diameters is 3 nm to 40 nm, and

wherein the substrate has one or more of the following coatings;

an antistatic coating;

or an adhesion promotion coating.

5. A multifunctional optical film for enhancing light extraction from a self-emissive light source having a surface that outputs light, comprising:

a flexible substrate substantially transmissive to light emitted by the self-emissive light source;

a structured layer of extraction elements having a first index of refraction,

wherein the extraction elements comprise nanoparticles disposed in a surface layer manner on the substrate, and the extraction elements form a non-planar surface of the structured layer, and

wherein the nanoparticles comprise first nanoparticles having diameters within a first range and second nanoparticles added to the first nanoparticles and having diameters in a second range less than and non-overlapping with the first range; and

a backfill layer comprising a material having a second index of refraction different from

the first index of refraction, wherein the backfill layer forms a planarizing layer over the nanoparticles on the non-planar surface of the structured layer, forming a planar surface on a side of the backfill layer opposite the nanoparticles,

wherein a substantial portion of the extraction elements are in optical communication with the light output surface of the self-emissive light source when the planar surface of the backfill layer is located against the light output surface of the self-emissive light source,

wherein the structured layer and backfill layer are in sufficient proximity to the light output surface of the self-emissive light source when the planar surface of the backfill layer is located against the light output surface of the self-emissive light source in order to at least partially enhance the extraction of light from the light output surface,

wherein the first range of diameters is 60 nm to 10 microns, and the second range of diameters is 3 nm to 40 nm, and

wherein the nanoparticles consist of one or more of the following;

metal oxide particles;

organic polymer particles;

metal particles;

or composite particles.

6. A multifunctional optical film for enhancing light extraction from a self-emissive light source having a surface that outputs light, comprising:

a flexible substrate substantially transmissive to light emitted by the self-emissive light source;

a structured layer of extraction elements having a first index of refraction,

wherein the extraction elements comprise nanoparticles disposed in a surface layer manner on the substrate, and the extraction elements form a non-planar surface of the structured layer, and

wherein the nanoparticles comprise first nanoparticles having diameters within a first range and second nanoparticles added to the first nanoparticles and having diameters in a second range less than and non-overlapping with the first range;

a backfill layer comprising a material having a second index of refraction different from

the first index of refraction, wherein the backfill layer forms a planarizing layer over the nanoparticles on the non-planar surface of the structured layer, forming a planar surface on a side of the backfill layer opposite the nanoparticles,

wherein a substantial portion of the extraction elements are in optical communication with the light output surface of the self-emissive light source when the planar surface of the backfill layer is located against the light output surface of the self-emissive light source,

wherein the structured layer and backfill layer are in sufficient proximity to the light output surface of the self-emissive light source when the planar surface of the backfill layer is located against the light output surface of the self-emissive light source in order to at least partially enhance the extraction of light from the light output surface, and

wherein the first range of diameters is 60 nm to 10 microns, and the second range of diameters is 3 nm to 40 nm; and

a stabilization layer located between the nanoparticles and the backfill layer.