Bismuth Coordination Compounds in OLED Hole Layers

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Solution Overview

Problem

Organic electroluminescence devices (OLEDs) face challenges in improving processability, lifespan, efficiency, operating voltage, and crosstalk due to high cross-conductivity between pixels, especially in small pixels with close spacing, leading to leakage currents and color impression degradation.

Innovation Solution

Incorporating a coordination compound with a bismuth atom in both the hole injection and hole transport layers, which reduces cross-conductivity and operating voltage while minimizing crosstalk, thereby enhancing the performance of OLEDs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional hole injection and transport layers are used, then processability and manufacturing are easier, but crosstalk between pixels increases due to high transverse conductivity

Engineering Contradiction:

ImprovecrosstalkVSAvoidprocessability

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent changes the chemical composition parameters of the hole injection and transport layers by incorporating bismuth coordination compounds with specific properties (low LUMO, low HOMO, appropriate mobility) to reduce transverse conductivity and minimize crosstalk while maintaining manufacturability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite material systems where bismuth coordination compounds are combined with conventional hole transport materials (such as arylamine compounds) to create layers that exhibit both low transverse conductivity and good processability, resolving the contradiction between reduced crosstalk and ease of manufacture

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If additional shadow masks are used to reduce crosstalk, then crosstalk between pixels decreases, but device complexity and manufacturing cost increase

Engineering Contradiction:

ImprovecrosstalkVSAvoidstructure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the need for additional shadow masks by incorporating functional bismuth coordination compounds directly into the hole injection and transport layers, thereby reducing device structural complexity while maintaining low crosstalk performance

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The bismuth coordination compounds act as intermediary substances that modify the electrical properties of the hole transport layers to reduce transverse conductivity, serving as a chemical mediator that replaces the need for physical shadow masks

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If arylamine compounds with p-dopants are used in the hole transport layer, then hole conductivity increases, but operating voltage and its increase during operation worsen

Engineering Contradiction:

Improvehole conductivityVSAvoidoperating voltage

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the doping parameters by using bismuth coordination compounds as p-dopants with optimized doping concentrations and properties, achieving high hole conductivity while controlling operating voltage and its increase during device operation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The bismuth coordination compounds create optimized charge transport pathways in the hole transport layer that facilitate hole conduction with lower energy barriers, reducing operating voltage while maintaining high hole conductivity

Inventive Principle:

Principle #31Porous materials

4Area of moving object

If pixels are made smaller with closer spacing, then display resolution improves, but crosstalk increases due to larger-area shared organic layers

Engineering Contradiction:

Improvepixel sizeVSAvoidcrosstalk

Core Design Contradiction:

Area of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent changes the electrical conductivity parameters of the shared organic layers by incorporating bismuth coordination compounds, enabling smaller pixel sizes with closer spacing while maintaining low transverse conductivity to prevent crosstalk

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 use of bismuth-containing coordination compounds in the hole injection and transport layers significantly reduces crosstalk and operating voltage, improving the overall performance and color accuracy of OLEDs, particularly in small pixel designs.

Implementation Method 1

a tactile sensor integrated into the touchscreen display to detect the position and force of a touch input

Methodology Applied

Scientific EffectTactile sensing:

Data Source

PatentEP4193399B1Electronic device

Publication Date: 2025.01.29 MERCK PATENT GMBH

Figure 1

AI summary

The invention relates to an electronic device comprising a coordination compound. The invention also relates to a method for producing said device.