Organic Light Emitting Element Electron Injection Layer Design

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Solution Overview

Problem

Current organic electroluminescence displays face challenges in achieving high emission efficiency and long lifetime due to inadequate electron transport properties and stability in light emitting elements.

Innovation Solution

A light emitting element is designed with a specific structure including a first electrode, a hole transport region, an emission layer, an electron transport region with a first electron injection layer and a second electron injection layer, where the first electron injection layer consists of compounds represented by Formulas 1 or 2, and the second electron injection layer includes a metal material, optimizing the thickness and composition for improved electron injection and transport.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional electron transport layer structure is used, then the device structure is simple, but the emission efficiency and element lifetime are insufficient

Engineering Contradiction:

Improveelement lifetimeVSAvoidelectron transport region structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The electron transport region is divided into multiple functional layers: electron transport layer, first electron injection layer, and second electron injection layer. This segmentation allows each layer to perform its specific function optimally, improving overall device reliability and lifetime while managing complexity through functional specialization.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses composite material structures in the electron transport region, combining organic compounds (Formula 1 or 2) with metal materials in the second electron injection layer. This composite approach enhances electron injection efficiency and stabilizes the electron transport process, leading to improved emission efficiency and element lifetime.

Inventive Principle:

Principle #40Composite materials

2Productivity

If materials with excellent electron transport properties are used, then emission efficiency improves, but material stability may be compromised

Engineering Contradiction:

Improveemission efficiencyVSAvoidmaterial stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent optimizes the thickness parameters of the electron injection layers (first electron injection layer: 5-20 nm, second electron injection layer: 1-5 nm) to achieve the best balance between electron transport efficiency and material stability. By carefully controlling these dimensional parameters, high emission efficiency is achieved while maintaining long-term operational stability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The first electron injection layer acts as an intermediary between the electron transport layer and the second electron injection layer. This intermediate layer facilitates smooth electron transport while protecting the underlying layers, thereby maintaining both high emission efficiency and material stability over time.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution enhances emission efficiency and extends the lifetime of light emitting elements by stabilizing electron injection and transport processes, leading to improved display performance.

Implementation Method 1

the electron transport region includes an electron transport layer on the emission layer, a first electron injection layer on the electron transport layer, and a second electron injection layer on the first electron injection layer

Methodology Applied

Scientific EffectElectron injection:

Implementation Method 2

The organic electroluminescence display is different from a liquid crystal display and is a display device of a self-luminescent type or kind in which holes and electrons respectively injected from a first electrode and a second electrode recombine in an emission layer of the organic electroluminescence display so that a light emitting material in the emission layer emits light

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentEP4456701A1Light emitting element and display device including the same

Publication Date: 2024.10.30 SAMSUNG DISPLAY CO LTD

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AI summary

A light emitting element includes a first electrode, a hole transport region on the first electrode, an emission layer on the hole transport region, an electron transport region on the emission layer, and a second electrode on the electron transport region. The electron transport region includes an electron transport layer on the emission layer, a first electron injection layer on the electron transport layer, and a second electron injection layer on the first electron injection layer, the thicknesses of the first and second electron injection layers are each about 1 nm to about 5 nm, the first electron injection layer includes a phenanthroline derivative and/or a phosphine oxide derivative, and the second electron injection layer includes a metal material.