Organic EL Element Mixed Layer Reduces Driving Voltage

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Solution Overview

Problem

Organic electroluminescent elements with multilayer laminate structures face challenges in charge injection due to differences in ionization potential and electron affinity at layer interfaces, leading to high driving voltage, low current efficiency, and power efficiency.

Innovation Solution

Incorporating a mixed layer with light-emitting and charge-transporting low molecular compounds in a film obtained by insolubilizing a polymer with insolubilizing groups, adjacent to a layer containing only light-emitting and charge-transporting low molecular compounds, to facilitate efficient charge transport and emission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a multilayer laminate structure is used to improve organic electroluminescent element performance, then the structural complexity increases, but the driving voltage increases due to interface hindrance in charge injection

Engineering Contradiction:

Improveelement performanceVSAvoidmultilayer laminate structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary layer between layers with different compositions in the multilayer laminate structure. This intermediary layer acts as a mediator to facilitate charge injection across the interface, reducing the hindrance caused by differences in ionization potential and electron affinity, thereby lowering the driving voltage while maintaining the benefits of the multilayer structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If a wet film-forming method is used to simplify manufacturing, then the ease of manufacture improves, but the current efficiency and power efficiency decrease compared to vacuum deposition

Engineering Contradiction:

Improvewet film-forming methodVSAvoidcurrent efficiency

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent modifies the parameters of the wet film-forming method by optimizing the composition, concentration, and processing conditions of the solution. This includes adjusting the solvent type, polymer molecular weight, and drying conditions to achieve film quality and electrical performance comparable to vacuum deposition, thereby maintaining ease of manufacture while improving current efficiency.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If a wet film-forming method is used to simplify manufacturing, then the ease of manufacture improves, but the driving voltage increases compared to vacuum deposition

Engineering Contradiction:

Improvewet film-forming methodVSAvoiddriving voltage

Core Design Contradiction:

Ease of manufactureVSStress or pressure

Solution Approach 1:

The patent optimizes parameters such as the polymer structure, solution concentration, and drying conditions to achieve better film quality with the wet film-forming method. This results in reduced defects and improved charge transport, thereby lowering the driving voltage while maintaining the manufacturing simplicity of the wet method.

Inventive Principle:

Principle #35Parameter changes

4Ease of manufacture

If a wet film-forming method is used to simplify manufacturing, then the ease of manufacture improves, but the power efficiency decreases compared to vacuum deposition

Engineering Contradiction:

Improvewet film-forming methodVSAvoidpower efficiency

Core Design Contradiction:

Ease of manufactureVSUse of energy by stationary object

Solution Approach 1:

The patent optimizes the wet film-forming process parameters to achieve better film quality and electrical performance. By improving the film uniformity and reducing defects through parameter optimization, the power efficiency is enhanced, bringing it closer to the levels achieved by vacuum deposition while retaining the ease of manufacture.

Inventive Principle:

Principle #35Parameter changes

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 results in an organic electroluminescent element with reduced driving voltage, enhanced current efficiency, and improved power efficiency, suitable for applications in displays and lighting systems.

Implementation Method 1

a film obtained by insolubilizing a polymer having insolubilizing groups

Methodology Applied

Scientific EffectInsolubilization:

Implementation Method 2

organic electroluminescent element comprising an anode, a cathode and an organic layer disposed between the anode and the cathode

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS9515277B2Organic electroluminescent element, organic EL display device and organic EL illumination

Publication Date: 2016.12.06 MITSUBISHI CHEM CORP

AI summary

To provide an organic electroluminescent element having a low driving voltage, high current efficiency and high voltage efficiency.An organic electroluminescent element comprising an anode, a cathode and an organic layer disposed between the anode and the cathode, wherein the organic layer comprises a mixed layer containing a light-emitting low molecular compound and/or a charge-transporting low molecular compound in a film containing an insolubilized polymer obtained by insolubilizing an insolubilizing polymer, and, adjacent to the mixed layer, a layer containing a light-emitting low molecular compound and a charge-transporting low molecular compound and not containing an insolubilized polymer.