Organic Electroluminescent Devices With Plasmonic Light Extraction

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Solution Overview

Problem

Existing OLEDs face challenges in efficiently extracting light due to high non-radiative decay rates and limited control over light emission characteristics, particularly in achieving saturated colors and high efficiency.

Innovation Solution

Incorporation of an enhancement layer with plasmonic materials and an outcoupling layer to manage surface plasmon resonance, reducing non-radiative decay and enhancing light extraction, combined with nanoparticle structures for controlled light emission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional OLED structures are used, then device simplicity is maintained, but light extraction efficiency is limited due to high non-radiative decay rates

Engineering Contradiction:

Improvelight extraction efficiencyVSAvoiddevice structure complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

An enhancement layer comprising plasmonic materials (such as silver nanoparticles or continuous metal film) is introduced as an intermediary between the organic emissive layer and the electrode. This enhancement layer mediates the interaction between excitons and photons, enabling surface plasmon resonance that increases radiative decay rates and improves light extraction efficiency without fundamentally redesigning the entire OLED structure

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The optical properties of the OLED are enhanced by changing the physical parameters of the enhancement layer, including metal nanoparticle size (5-100 nm), metal thickness (1-100 nm), and dielectric layer thickness (10-200 nm). These parameter adjustments optimize surface plasmon resonance conditions to maximize light extraction while maintaining device simplicity

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If white OLED with color filters is used, then saturated colors can be achieved, but light extraction efficiency and internal quantum efficiency are reduced

Engineering Contradiction:

Improvecolor saturationVSAvoidinternal quantum efficiency

Core Design Contradiction:

Illumination intensityVSProductivity

Solution Approach 1:

The patent converts the previously harmful non-radiative decay at metal interfaces into a beneficial effect by utilizing surface plasmon resonance. The plasmonic enhancement layer transforms non-radiative energy loss into enhanced radiative emission, achieving both high internal quantum efficiency and saturated colors without requiring color filters

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The emission color and saturation are controlled by adjusting the optical resonance properties of the plasmonic enhancement layer. By varying metal nanoparticle size, shape, and composition, or metal layer thickness, the resonant wavelength is tuned to enhance emission at specific wavelengths, achieving saturated colors directly from the emissive layer without color filtering

Inventive Principle:

Principle #32Color changes

3Productivity

If plasmonic materials are added to enhance light extraction, then internal quantum efficiency improves, but device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improveinternal quantum efficiencyVSAvoidfabrication ease

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The enhancement layer is segmented into functionally distinct components: a dielectric layer providing spacing and optical coupling, and a plasmonic metal layer (continuous or nanoparticulate) providing surface plasmon resonance. This segmentation allows each layer to be optimized and fabricated using standard techniques, with the dielectric layer deposited by sputtering or evaporation and the metal layer added subsequently, simplifying the overall manufacturing process

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Improves light extraction efficiency and emission characteristics, enabling higher internal quantum efficiency and better color control, surpassing conventional limits.

Implementation Method 1

an enhancement layer with plasmonic materials and an outcoupling layer to manage surface plasmon resonance, reducing non-radiative decay and enhancing light extraction

Methodology Applied

Scientific EffectSurface plasmon resonance: Resonance

Implementation Method 2

OLEDs make use of thin organic films that emit light when voltage is applied across the device

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS12414433B2Organic electroluminescent devices

Publication Date: 2025.09.09 UNIVERSAL DISPLAY CORP

AI summary

Emissive devices are provided that include an outcoupling layer having a plurality of nanoparticles such that the outcoupling layer has at least 3 regions possessing distinct bulk refractive index values. One or more dielectric materials are arranged at least partially between the outcoupling layer and an emissive layer of the device.