Molybdenum Tungsten Oxide Hole Injection Layer for Organic EL

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Solution Overview

Problem

Current organic electroluminescence (EL) element manufacturing methods face challenges in achieving high luminance efficiency and large-scale production due to issues with mask alignment accuracy, film uniformity, and high drive voltage, particularly when using vacuum deposition, while wet processing methods struggle with layer formation and material solubility.

Innovation Solution

A top-emission organic EL element is developed with a hole injection layer composed of a mixture of molybdenum oxide and tungsten oxide, containing a molybdenum element at a ratio of 9 to 35 atomic %, which improves hole injection performance, surface flatness, and reduces solubility in aqueous solutions, enabling lower drive voltage and higher luminance efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If vacuum deposition method is used to form luminescent layer, then mask alignment accuracy and film uniformity are maintained, but manufacturing cost increases and large-scale production becomes difficult

Engineering Contradiction:

Improvemask alignment accuracyVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent changes the deposition method from vacuum deposition to wet processing, fundamentally altering the manufacturing parameter. This allows large-scale production while maintaining acceptable film uniformity through solution-based deposition, resolving the contradiction between manufacturing precision and ease of manufacture

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical vacuum deposition system with a wet chemical processing system. This substitution enables simpler, more cost-effective manufacturing processes suitable for large-scale production while achieving comparable film quality through chemical deposition mechanisms

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If wet processing is used to form organic layers, then manufacturing cost decreases and material use efficiency improves, but lower layers are eluted into the solution causing performance degradation

Engineering Contradiction:

Improvemanufacturing costVSAvoidlayer stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by making each organic layer have different solubility characteristics. The first organic layer uses materials with low solubility in the second layer's solvent, preventing elution. This localized differentiation of material properties resolves the contradiction between ease of manufacture and layer stability

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent introduces solvent selection as an intermediary mechanism. By carefully choosing solvents for each layer that do not dissolve underlying layers, the system enables wet processing of multiple layers without elution. This intermediary control of chemical compatibility resolves the contradiction between manufacturing ease and reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

3Power

If high drive voltage is applied to organic EL element, then sufficient current flows through the device, but luminance efficiency decreases and device lifetime shortens

Engineering Contradiction:

Improvecurrent flowVSAvoidluminance efficiency

Core Design Contradiction:

PowerVSUse of energy by moving object

Solution Approach 1:

The patent implements self-service by creating a hole injection layer that automatically facilitates hole injection into the organic layers. This layer, formed by wet processing, provides sustained hole supply without requiring high external voltage, enabling the device to maintain current flow at lower voltages and thus improving luminance efficiency and lifetime

Inventive Principle:

Principle #25Self-service

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 solution facilitates the production of large-scale organic EL panels with improved luminance efficiency and reduced manufacturing costs by ensuring reliable hole injection, preventing pinhole formation, and maintaining film thickness uniformity, thus enabling mass production with lower drive voltage requirements.

Implementation Method 1

a hole injection layer which is formed between the anode and the organic luminescent layer and is a mixture of molybdenum oxide and tungsten oxide

Methodology Applied

Scientific EffectHole injection: Conduction (electrical)

Implementation Method 2

an organic layer including a luminescent layer... takes out illumination by injecting holes through the anode and electrons through the cathode and recombining the injected holes and electrons inside the luminescent layer

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS8174009B2Organic electroluminescence element and manufacturing method thereof

Publication Date: 2012.05.08 MAGNOLIA BLUE CORP

AI summary

To provide an organic electroluminescence element including a structure that facilitates manufacturing of a large scale organic EL panel and a manufacturing method thereof, the organic electroluminescence element includes: an anode; a cathode; an organic luminescent layer located between the anode and the cathode; and a hole injection layer located between the anode and the organic luminescent layer. The hole injection layer comprises a mixture of molybdenum oxide and tungsten oxide that contains a molybdenum element in a range of 9 atomic percent to 35 atomic percent.