Organometallic Cathode for OLED Stability and Cost Reduction

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Solution Overview

Problem

OLED devices using metal or metal alloy cathodes face degradation and high costs due to poor chemical stability and high material costs, which affect their performance and longevity.

Innovation Solution

The use of an organometallic layer with an organic metal as the cathode, having a work function ranging from 2.9 eV to 3.7 eV, improves electron injection efficiency and stability, reducing the need for additional electron injection layers and lowering production costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metal or metal alloy is used as the cathode to achieve low work function for efficient electron injection, then electron injection efficiency is improved, but the device deteriorates in atmospheric environment and quality degrades

Engineering Contradiction:

Improveelectron injection efficiencyVSAvoidchemical stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent replaces expensive, unstable metal cathodes with an organometallic compound cathode that, while having comparable electron injection performance, offers superior chemical stability and longevity, effectively replacing a 'short-living' metal component with a more durable organic alternative

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent uses an organometallic compound (Fe(C5H5)2) that combines metal center with organic ligands, creating a composite material that exhibits both the low work function of metals and the chemical stability of organic compounds, resolving the contradiction between electron injection efficiency and atmospheric stability

Inventive Principle:

Principle #40Composite materials

2Reliability

If a metal or metal alloy is used as the cathode to achieve low work function, then electron injection efficiency is improved, but the cost of the device increases

Engineering Contradiction:

Improveelectron injection efficiencyVSAvoidproduction cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent substitutes expensive metal or metal alloy materials with an organometallic compound that can be deposited at lower costs, reducing material expenses while maintaining the necessary electrical performance for efficient electron injection

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the material parameter from inorganic metal to organic metal compound, which allows for alternative deposition methods and reduces material costs while achieving the required work function range (2.9-3.7 eV) for efficient electron injection

Inventive Principle:

Principle #35Parameter changes

3Reliability

If additional electron injection layers are added to improve electron injection, then electron injection efficiency is improved, but the device thickness increases

Engineering Contradiction:

Improveelectron injection efficiencyVSAvoiddevice thickness

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The organometallic cathode layer performs multiple functions simultaneously: it serves as both the electron injection layer and the cathode, eliminating the need for separate electron injection layers and thereby reducing overall device thickness while maintaining efficient electron injection

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the functions of the electron injection layer and the cathode into a single organometallic layer, combining electron injection capability with cathode functionality to reduce the number of layers and overall device thickness

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

The organometallic layer enhances the luminous efficiency and stability of OLED devices, offering improved electron transmission and reduced thickness, while maintaining low costs and chemical stability, suitable for ultra-thin designs.

Implementation Method 1

a work function of the cathode material must be low enough to meet the requirement of injecting electrons into the organic light-emitting material efficiently

Methodology Applied

Scientific EffectElectron injection:

Implementation Method 2

under an action of an applied electric field, electrons and holes are injected into an organic light-emitting material from a cathode and an anode respectively, electrons and holes migrate, recombine and attenuate in the organic light-emitting material to emit light

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS10411217B2OLED device and preparation method therefor and display apparatus

Publication Date: 2019.09.10 BOE TECHNOLOGY GROUP CO LTD

AI summary

An OLED device and a manufacturing method thereof and a display apparatus are provided. The OLED device includes an anode, a cathode, and a functional layer disposed between the anode and the cathode, the cathode includes an organometallic layer, and the organometallic layer includes an organic metal. The OLED device is capable of increasing the stability of the cathode in the OLED device and reducing the cost of the OLED device.