OLED Capping Layer Compound for Light Extraction and Film Stability

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Solution Overview

Problem

Existing organic light emitting devices face challenges in achieving high external luminous efficiency and stability due to light reflection and loss, with current capping layers lacking sufficient refractive index and thin film stability.

Innovation Solution

A capping layer compound is developed with a fused ring structure linked to an arylamine via a linker, featuring high refractive index, large band gap, and improved stability against external factors, minimizing bulky characteristics and enhancing intermolecular reactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional organic compounds are used for capping layer, then device structure is simple, but refractive index is low and light extraction efficiency is poor

Engineering Contradiction:

Improvelight extraction efficiencyVSAvoidmolecular structure complexity

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The patent employs composite molecular structures combining fused rings (for high refractive index) with arylamine groups (for stability and charge transport), creating a material that simultaneously achieves high refractive index (n≥2.0) and excellent device performance without requiring multiple separate layers

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent systematically varies molecular parameters including introducing fused ring structures, adjusting heteroatom types (N, O, S, Se, Te), and modifying linker groups to optimize the refractive index while maintaining film stability and charge transport properties

Inventive Principle:

Principle #35Parameter changes

2Reliability

If conventional capping layer materials are used, then material deposition is easy, but thin film stability under operational heat is insufficient

Engineering Contradiction:

Improvethin film stabilityVSAvoiddeposition process difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent introduces specific functional groups at different molecular positions: fused rings provide local high refractive index and stability, while arylamine groups provide local charge transport capability and thermal stability, with linkers providing flexibility for deposition

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses linker groups as intermediary structures connecting the fused ring core to the arylamine functional groups, enabling independent optimization of each component's properties while maintaining overall molecular stability and deposition characteristics

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If capping layer compound absorbs visible light, then band gap is small, but light absorption in visible region increases reducing device efficiency

Engineering Contradiction:

Improvedevice efficiencyVSAvoidvisible light absorption

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent optimizes the HOMO-LUMO energy gap by adjusting molecular structure parameters including fused ring types, heteroatom selections, and substituent positions to achieve band gaps that prevent visible light absorption while maintaining high refractive index for light extraction

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the potential harmful effect of strong light absorption by fused rings into a beneficial property by carefully selecting heteroatoms and molecular configurations that shift absorption to UV region, thereby achieving both high refractive index and high visible light transmission

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

4Stability of the object's composition

If bulky structures are used in capping layer compound, then molecular stability is high, but intermolecular reaction characteristics deteriorate

Engineering Contradiction:

Improvemolecular stabilityVSAvoidintermolecular reaction characteristic

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent segments the molecular structure into distinct functional modules: fused ring core for stability, linker for flexibility and reaction capability, and arylamine groups for charge transport, allowing each segment to be optimized independently for its specific function

Inventive Principle:

Principle #1Segmentation

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 compound improves the external quantum efficiency and lifespan of the organic light emitting device by increasing refractive index, reducing light absorption in visible light regions, and maintaining stable thin films under operational heat.

Implementation Method 1

various organic compounds having a refractive index of 1.7 or higher have been used as an application for a capping layer to prevent the total reflection and loss of light going out to the outside

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

the compound having a large band gap not to be able to absorb a visible light region

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentUS12441684B2Organic compound for capping layer and organic light emitting diode comprising the same

Publication Date: 2025.10.14 DONGJIN SEMICHEM CO LTD

AI summary

As a compound for a capping layer for an organic light emitting device, disclosed is a capping layer compound represented by Formula 1 below. In addition, an organic light emitting device including the capping layer compound is also disclosed.