Organic Electroluminescent Element Metal Diffusion Barrier

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Solution Overview

Problem

The use of electron injection layers with metal doping in organic electroluminescent elements can lead to metal diffusion into the light-emitting layer, reducing light emission efficiency.

Innovation Solution

Incorporating a metal thin film or metal alloy with a metal identical to the doping metal in the electron transport or injection layer, and a diffusion barrier layer to suppress metal diffusion, while maintaining efficient electron injection and transport.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an electron injection layer with metal doping is used to improve electron injection efficiency, then carrier injection is enhanced, but metal diffuses into the light-emitting layer causing reduction in light emission efficiency

Engineering Contradiction:

Improvecarrier injection efficiencyVSAvoidmetal diffusion

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces an electron transport layer as an intermediary between the light-emitting layer and the electron injection layer. This intermediate layer prevents direct contact between the light-emitting layer and the metal-doped injection layer, thereby blocking metal diffusion while still allowing electron transport. The electron transport layer acts as a mediator that separates the harmful metal-containing layer from the light-emitting layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent divides the electron injection and transport function into two separate layers: an electron injection layer (with metal doping) and an electron transport layer (without metal doping). This segmentation isolates the metal-containing injection layer from the light-emitting layer, preventing metal diffusion while maintaining efficient electron injection and transport through the divided functional layers.

Inventive Principle:

Principle #1Segmentation

2Object-generated harmful factors

If a diffusion barrier layer is introduced to prevent metal diffusion, then light emission efficiency is maintained, but device structure becomes more complex

Engineering Contradiction:

Improvemetal diffusion suppressionVSAvoidlayer structure complexity

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The electron transport layer serves multiple functions simultaneously: it transports electrons from the injection layer to the light-emitting layer, and it acts as a diffusion barrier to prevent metal diffusion into the light-emitting layer. By combining these two functions in a single layer, the patent avoids the need for an additional dedicated diffusion barrier layer, thus maintaining structural simplicity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the electron transport function and the metal diffusion barrier function into a single electron transport layer. This layer is positioned between the metal-doped injection layer and the light-emitting layer, where it simultaneously performs electron transport and blocks metal diffusion, eliminating the need for separate functional layers.

Inventive Principle:

Principle #5Merging (Combining)

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

This configuration effectively prevents metal diffusion into the light-emitting layer, thereby enhancing light emission efficiency and maintaining low driving voltage.

Implementation Method 1

The organic electroluminescent elements each generate excitons through recombination, in a light-emitting layer, of electrons injected from a cathode and holes injected from an anode and emit light when the excitons return to a low energy level or a ground state

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

Electron injection, which is one of techniques for carrier injection, uses an electron injection layer as an organic layer through which electrons are injected into a light-emitting layer. The electron injection layer includes an organic material doped with a low-work function metal.

Methodology Applied

Scientific EffectElectron injection:

Implementation Method 3

Unfortunately, the use of such an electron injection layer may cause diffusion, into the light-emitting layer, of the metal doped in the electron injection layer

Methodology Applied

Scientific EffectMetal diffusion: Diffusion

Data Source

PatentUS10529941B2Organic electroluminescent element, organic electroluminescent unit, and electronic apparatus

Publication Date: 2020.01.07 MAGNOLIA BLUE CORP

AI summary

An organic electroluminescent element includes, in order, a first electrode, an organic light-emitting layer, a metal thin film including a metal or a metal alloy, an organic electron transport layer doped with a metal, and a second electrode. The metal in the metal thin film is identical to the metal doped in the organic electron transport layer. The metal alloy in the metal thin film includes a metal identical to the metal doped in the organic electron transport layer.