OLED Emissive Layer Composition for Narrow-Gamut High-Efficiency Emission

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Solution Overview

Problem

Existing organic electroluminescent devices struggle to combine high efficiency, long lifetime, and good color purity, particularly in achieving the BT-2020 and DCPI3 color gamut, due to broad emission spectra and high costs associated with transition metal-based phosphorescence materials.

Innovation Solution

Incorporating a light-emitting layer composed of sublayers containing a host material, a phosphorescence material, a small full width at half maximum (FWHM) emitter, and optionally a thermally activated delayed fluorescence (TADF) material, with each emitter having specific energy levels and narrow emission spectra, to enhance energy transfer and achieve desired color gamut and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If phosphorescence materials based on transition metals are used, then high efficiency and long lifetime are achieved, but cost increases and color purity deteriorates due to broad emission spectrum

Engineering Contradiction:

ImprovelifetimeVSAvoidcost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive transition metal-based phosphorescence materials with organic fluorescence or TADF emitters that are cheaper and more abundant, accepting that individual emitter molecules have shorter operational lifetimes but achieving overall device longevity through efficient energy transfer and material design

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the emission mechanism from phosphorescence to fluorescence/TADF, and modifies the emission spectrum width parameter by selecting specific organic emitters with narrow emission profiles (FWHM ≤ 0.25 eV) to achieve both cost reduction and improved color purity

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If phosphorescence materials are used, then high efficiency is achieved, but color purity deteriorates due to broad emission spectrum

Engineering Contradiction:

ImproveefficiencyVSAvoidcolor purity

Core Design Contradiction:

Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The patent introduces an energy transfer mediator system where phosphorescence or TADF materials transfer energy to fluorescence emitters with narrow emission spectra, acting as an intermediary that converts broad phosphorescence emission into narrow fluorescence emission while maintaining high efficiency

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates composite light-emitting layers combining multiple materials (phosphorescence materials, TADF materials, and fluorescence emitters) with complementary properties to achieve both high efficiency and narrow emission spectrum simultaneously

Inventive Principle:

Principle #40Composite materials

3Manufacturing precision

If fluorescence or TADF emitters with narrow emission spectrum are used, then color purity is improved, but efficiency and lifetime deteriorate due to roll-off behavior and exciton annihilation

Engineering Contradiction:

Improvecolor purityVSAvoidefficiency

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent uses phosphorescence or TADF materials as energy transfer mediators that receive excitons efficiently and transfer energy to fluorescence emitters, bypassing the efficiency limitations of direct fluorescence emission at high luminance

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs phosphorescence or TADF materials to pre-process excitons and energy transfer before reaching the fluorescence emitter, preparing the energy in a form that can be emitted with narrow spectrum while maintaining high efficiency through the intermediary's superior exciton handling

Inventive Principle:

Principle #10Preliminary action

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

The proposed configuration results in an organic electroluminescent device with a long lifetime, high quantum yield, and narrow emission, suitable for achieving the BT-2020 and DCPI3 color gamut, while reducing the reliance on expensive transition metals.

Implementation Method 1

Herein, a phosphorescence material and/or an optional TADF material might transfer energy to a small full width at half maximum (FWHM) emitter displaying emission of light.

Methodology Applied

Scientific EffectEnergy transfer:

Implementation Method 2

The energy pump may for example be a TADF material displaying reversed-intersystem crossing (RISC)

Methodology Applied

Scientific EffectThermally activated delayed fluorescence:

Implementation Method 3

at least one host material H B

Methodology Applied

Scientific EffectEnergy transfer:

Data Source

PatentEP4214769B1Organic electroluminescent device

Publication Date: 2025.12.03 SAMSUNG DISPLAY CO LTD

AI summary

The present invention relates to a an organic electroluminescent device comprising at least one light-emitting layer B composed of one or more sublayers, wherein the one or more sublayers of the light-emitting layer B as a whole comprise at least one host material HB, at least one phosphorescence material PB, at least one small FWHM emitter SB, and optionally at least one TADF material EB, wherein SB emits light with a full width at half maximum (FWHM) of less than or equal to 0.25 eV.