Organic Electroluminescent Element Interface Adjustment Layer

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Solution Overview

Problem

Existing organic electroluminescent elements with resistive layers to suppress short-circuiting experience a significant increase in driving voltage due to interfacial barriers caused by differences in electron levels between layers.

Innovation Solution

Incorporating an interface adjustment layer with a specific resistance higher than the second electrode but lower than the resistive layer, positioned between the organic layer and the resistive layer, to mitigate the increase in driving voltage while maintaining effective short-circuit suppression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a resistive layer is added to suppress short-circuiting, then short-circuit suppression is improved, but driving voltage increases significantly

Engineering Contradiction:

Improveshort-circuit suppressionVSAvoiddriving voltage

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The resistive layer is divided into multiple sub-layers with different specific resistance values. The first resistive sub-layer has a lower specific resistance than the second resistive sub-layer, creating a gradient structure that gradually transitions from the organic electroluminescent layer to the electrode. This segmentation reduces the abrupt interfacial barrier and minimizes driving voltage increase while maintaining effective short-circuit suppression.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the resistive layer are assigned different specific resistance values based on their position and function. The first resistive sub-layer closer to the organic electroluminescent layer has lower resistance to facilitate charge transport, while the second resistive sub-layer has higher resistance to provide stronger short-circuit suppression. This local quality variation optimizes both electrical performance and short-circuit protection.

Inventive Principle:

Principle #3Local quality

2Reliability

If a resistive layer with high specific resistance is used to suppress short-circuiting, then short-circuit suppression is improved, but driving voltage increases significantly

Engineering Contradiction:

Improveshort-circuit suppressionVSAvoiddriving voltage

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The specific resistance parameter of the resistive layer is changed by dividing it into sub-layers with different resistance values. Instead of using a single high-resistance layer that causes large voltage increase, the patent uses a gradient structure where resistance parameters vary across layers, achieving short-circuit suppression with minimal voltage penalty.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The resistive layer is constructed as a composite structure with multiple sub-layers having different electrical properties. This composite approach combines the benefits of both lower-resistance and higher-resistance materials in a single integrated layer, optimizing the balance between charge transport and short-circuit suppression.

Inventive Principle:

Principle #40Composite materials

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 interface adjustment layer effectively reduces the driving voltage increase, allowing for significant suppression of short-circuiting without excessive voltage elevation, achieved by controlling the specific resistances and oxygen rates during the sputtering process.

Implementation Method 1

an interface adjustment layer, a resistive layer... The interface adjustment layer has a specific resistance higher than the specific resistance of the second electrode and lower than the specific resistance of the resistive layer

Methodology Applied

Scientific EffectElectron level alignment: Electrical Resistance

Implementation Method 2

controlling the specific resistances and oxygen rates during the sputtering process

Methodology Applied

Scientific EffectSputtering: Sputtering

Data Source

PatentUS10892431B2Organic electroluminescent element

Publication Date: 2021.01.12 MAGNOLIA BLUE CORP

AI summary

An organic electroluminescent element includes, in order, a first electrode, an organic layer that includes an organic electroluminescent layer, an interface adjustment layer, a resistive layer, and a second electrode. The resistive layer has a specific resistance higher than a specific resistance of the second electrode. The interface adjustment layer has a specific resistance higher than the specific resistance of the second electrode and lower than the specific resistance of the resistive layer.