Organic Electroluminescence Device with Gradient Phosphorescent Concentration

Solution Overview

Problem

Existing organic electroluminescence devices struggle to achieve high external quantum efficiency despite elongated service life, as previous attempts have focused on extending lifespan rather than enhancing efficiency.

Innovation Solution

An organic electroluminescence device with a specific layer structure comprising a hole injection layer, hole transport layer, and emission layer, each containing a phosphorescent light-emitting material, where the concentration of the phosphorescent material is optimized across layers to enhance efficiency, and the use of a host material and arylamine derivative with controlled ionization potential and solvent solubility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If the service life of organic electroluminescence devices is elongated by using host materials in emission and hole transport layers, then the durability is improved, but the external quantum efficiency remains low

Engineering Contradiction:

Improveservice lifeVSAvoidexternal quantum efficiency

Core Design Contradiction:

Duration of action of stationary objectVSUse of energy by moving object

Solution Approach 1:

The patent applies local quality by creating a gradient concentration distribution of phosphorescent light-emitting material across different layers. The hole injection layer has the highest concentration (10-50% by mass), the hole transport layer has intermediate concentration (0.1-10% by mass), and the emission layer has the lowest concentration (0.01-1% by mass). This localized variation in material concentration optimizes both durability (through host material presence) and external quantum efficiency (through strategic phosphorescent material distribution) in different device regions.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the concentration parameter of phosphorescent light-emitting material across layers to resolve the contradiction. By systematically varying the concentration from high in the hole injection layer to low in the emission layer, the patent achieves both extended service life (via host materials in all layers) and high external quantum efficiency (via optimized phosphorescent material distribution), transforming a single-parameter approach into a multi-parameter optimization strategy.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If phosphorescent light-emitting material concentration is increased in the hole injection layer, then the external quantum efficiency is improved, but the material cost and complexity increase

Engineering Contradiction:

Improveexternal quantum efficiencyVSAvoidlayer structure complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent segments the organic layer into three distinct functional layers with different phosphorescent material concentrations: hole injection layer (10-50%), hole transport layer (0.1-10%), and emission layer (0.01-1%). This segmentation allows each layer to be optimized independently for its specific function while maintaining overall device efficiency, reducing the need for excessive phosphorescent material in less critical regions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by creating a gradient concentration distribution of phosphorescent light-emitting material across different layers. The hole injection layer has the highest concentration (10-50% by mass), the hole transport layer has intermediate concentration (0.1-10% by mass), and the emission layer has the lowest concentration (0.01-1% by mass). This localized variation in material concentration optimizes both durability (through host material presence) and external quantum efficiency (through strategic phosphorescent material distribution) in different device regions.

Inventive Principle:

Principle #3Local quality

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 optimized layer structure and material concentrations significantly improve external quantum efficiency and durability of the organic electroluminescence device, enabling better power efficiency and longer operational life.

Implementation Method 1

the hole injection layer, the hole transport layer and the emission layer each contain a phosphorescent light-emitting material

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Data Source

PatentUS9935275B2Organic electroluminescence device and method for producing the same

Publication Date: 2018.04.03 UDC IRELAND

AI summary

An organic electroluminescence device including an anode, a cathode, an organic layer disposed between the anode and the cathode, the organic layer containing a hole injection layer, a hole transport layer and an emission layer containing a host material, wherein the hole injection layer, the hole transport layer and the emission layer each contain a phosphorescent light-emitting material, wherein the hole injection layer contains the phosphorescent light-emitting material in an amount of 10% by mass or more but less than 50% by mass, and wherein a concentration of the phosphorescent light-emitting material contained in the hole transport layer is lower than that in the hole injection layer, and a concentration of the phosphorescent light-emitting material contained in the emission layer is lower than that in the hole injection layer and higher than that in the hole transport layer.