Phenanthroline Organic Compound for OLED Charge Generation Layer Stability

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Solution Overview

Problem

The existing charge generation layers in OLEDs suffer from thermal and electric instability, leading to reduced electron injection efficiency and shortened lifetimes due to metal diffusion and energy level differences, which affects the overall performance and longevity of white LEDs with tandem structures.

Innovation Solution

An organic compound with a phenanthroline moiety substituted with an aromatic ring is used in the charge generation and electron transporting layers, enhancing thermal stability, preventing metal diffusion, and improving electron injection efficiency by forming a gap state with alkali metals, thereby reducing driving voltage and extending LED lifetime.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metal-doped N type charge generation layer is used in tandem structure LED, then electron injection efficiency is improved, but metal diffusion occurs and LED lifetime is reduced

Engineering Contradiction:
Improveelectron injection efficiencyVSAvoidLED lifetime
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent introduces an organic compound as an intermediary material between the metal dopant and the P type charge generation layer. This compound acts as a barrier that prevents metal diffusion while maintaining the electrical function of the N type charge generation layer, thus preserving both electron injection efficiency and LED lifetime.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the chemical and physical parameters of the charge generation layer by selecting specific organic compounds with appropriate energy levels, mobility characteristics, and thermal stability. These parameter changes enable the layer to maintain electron injection efficiency without the harmful side effect of metal diffusion.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If conventional charge generation layer materials are used, then device structure is simple, but thermal stability and electric stability are poor

Engineering Contradiction:
Improvecharge generation layer structureVSAvoidthermal stability and electric stability
Core Design Contradiction:
Device complexityVSStability of the object's composition

Solution Approach 1:

The patent changes the material parameters by selecting organic compounds with high thermal decomposition temperatures, appropriate HOMO-LUMO energy levels, and good charge mobility. These parameter changes directly improve thermal and electric stability while maintaining a relatively simple single-layer structure.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material strategies by combining organic compounds with specific functional groups (such as electron-transporting moieties and aromatic rings) to create a charge generation layer that exhibits both structural simplicity and enhanced stability properties.

Inventive Principle:
Principle #40Composite materials

3Productivity

If energy level difference between N type and P type charge generation layers is large, then charge separation is efficient, but electron injection into N type layer is deteriorated

Engineering Contradiction:
Improvecharge separation efficiencyVSAvoidelectron injection efficiency
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent optimizes the energy level parameters of the organic compound in the N type charge generation layer. By carefully selecting compounds with appropriate HOMO and LUMO levels, the patent achieves a balanced energy level alignment that enables both efficient charge separation at the interface and smooth electron injection into the N type layer.

Inventive Principle:
Principle #35Parameter changes

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 organic compound improves thermal stability, electron transporting properties, and reduces driving voltage while extending the lifetime of LEDs by enhancing electron injection and preventing metal diffusion, resulting in improved emission efficiency and stability.

Implementation Method 1

improving electron injection efficiency by forming a gap state with alkali metals

Methodology Applied
Scientific EffectGap state formation:

Implementation Method 2

electron transporting properties are improved

Methodology Applied
Scientific EffectElectron transport: Conduction (electrical)

Data Source

PatentEP3333921B1Organic compound, light emitting diode and organic light emitting diode display
Publication Date: 2024.05.08 LG DISPLAY CO LTD
  • EP3333921B1 patent drawingFigure 1
  • EP3333921B1 patent drawingFigure 2
  • EP3333921B1 patent drawingFigure 3

AI summary

The present disclosure relates to an organic compound, a light emitting diode and an organic light emitting diode display device using the same. The organic compound is represented by a following chemical formula 1. This organic compound has the advantages in the electron transmitting property and the thermal stability and forms a stable gap state with an alkali metal and an alkali earth metal. The driving voltage of the light emitting diode is reduced and the emission efficiency and the lifetime of the light emitting diode are improved by applying the organic compound to the charge generation layer and/or the electron transporting layer of the light emitting diode of the tandem structure.