Multi-Stack OLED Charge Generation Electron Transport Layer

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Organic light emitting display devices with a multi-stack structure have a higher driving voltage due to increased hetero-junction interfaces, leading to higher power consumption compared to single-stack structures.

Innovation Solution

The use of a light emitting device with a multi-stack structure where at least one of the charge generation layers comprises the same electron transporting material as the adjacent electron transport layer, reducing the number of hetero-junction interfaces and minimizing charge trapping, thereby decreasing driving voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a multi-stack structure is used to enhance display performance, then the display capability is improved, but the driving voltage increases due to more hetero-junction interfaces

Engineering Contradiction:

Improvedisplay capabilityVSAvoiddriving voltage

Core Design Contradiction:

Adaptability or versatilityVSPower

Solution Approach 1:

The patent merges the charge generation layer and electron transport layer into a single integrated layer. This charge generation electron transport layer combines the functions of charge generation and electron transport, eliminating the hetero-junction interface between these two layers. The multi-stack structure maintains its display enhancement capability while reducing the total number of hetero-junction interfaces, thereby lowering charge trapping and driving voltage.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The charge generation electron transport layer performs multiple functions simultaneously: it generates charges and transports electrons. This multi-functional layer reduces the number of separate layers needed, decreasing the number of hetero-junction interfaces in the multi-stack structure while maintaining all necessary functions for enhanced display performance.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If a multi-stack structure is used to improve display performance, then the display capability is enhanced, but power consumption increases due to higher driving voltage

Engineering Contradiction:

Improvedisplay performanceVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

By combining the charge generation layer and electron transport layer into one integrated layer, the patent eliminates unnecessary hetero-junction interfaces. This reduction in interfaces decreases charge trapping, which directly lowers the driving voltage required for operation, thereby reducing power consumption while maintaining enhanced display performance.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If more electron transport layers are added to the multi-stack structure, then the charge balance is improved, but the number of hetero-junction interfaces increases leading to higher driving voltage

Engineering Contradiction:

Improvecharge balanceVSAvoiddriving voltage

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent applies the merging principle to each stack in the multi-stack structure, combining the charge generation layer and electron transport layer into a single charge generation electron transport layer. This approach maintains proper charge balance across multiple stacks while minimizing the number of hetero-junction interfaces, preventing the driving voltage from increasing despite having multiple stacks.

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 approach results in a reduced driving voltage and lower power consumption for organic light emitting display devices with a multi-stack structure, improving their efficiency and performance.

Implementation Method 1

at least any one of the N-type charge generation layer and the P-type charge generation layer comprises the same electron transporting material as that of an electron transport layer of one of the stacks that is adjacent to the N-type charge generation layer

Methodology Applied

Scientific EffectElectron transport: Conduction (electrical)

Data Source

PatentUS9105861B2Light emitting device and organic light emitting display device including the same

Publication Date: 2015.08.11 LG DISPLAY CO LTD

AI summary

A light emitting device includes first and second electrodes facing each other on a substrate, a plurality of stacks stacked between the first and second electrodes and each including an EML so as to emit particular light, and a charge generation layer formed between the stacks so as to adjust charge balance therebetween and including an N-type charge generation layer and a P-type charge generation layer, wherein at least any one of the N-type charge generation layer and the P-type charge generation layer includes the same electron transporting material as that of an electron transport layer of one of the stacks that is adjacent to the N-type charge generation layer.