Anthracene Derivatives for OLED Host Materials

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Solution Overview

Problem

Organic electroluminescent devices, particularly those emitting blue light, face challenges with short operating lifetime and inadequate efficiency, along with host materials that tend to crystallize instead of forming glass-like films due to low glass-transition temperatures.

Innovation Solution

Development of phenylanthracene derivatives with specific divalent groups linking anthracene units, such as fluorene and heteroaryl groups, which are used in organic electroluminescent devices to enhance efficiency, lifetime, and reduce crystallization tendencies by forming compounds with higher glass-transition temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional host materials are used in organic electroluminescent devices, then device structure is simple, but operating lifetime is short and efficiency is inadequate

Engineering Contradiction:

Improveoperating lifetimeVSAvoidcompound structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent modifies the chemical structure parameters of host materials by introducing specific anthracene derivatives with controlled substitution patterns. The compounds feature anthracene core units with strategically placed phenyl, naphthyl, or heteroaryl groups at specific positions (2,6- or 9,10-positions), which optimizes molecular weight, glass transition temperature, and crystallization behavior to achieve extended device lifetime and improved efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates composite molecular structures by combining anthracene units with diverse aromatic groups (phenyl, naphthyl, heteroaryl) through covalent bonding. These composite structures integrate the beneficial properties of each component: anthracene provides high glass transition temperature and low crystallization tendency, while the aromatic substituents tune electronic properties for efficient charge transport and long operational stability

Inventive Principle:

Principle #40Composite materials

2Productivity

If conventional host materials are used, then manufacturing process is simple, but efficiency is inadequate particularly in blue emission

Engineering Contradiction:

Improvedevice efficiencyVSAvoidmaterial synthesis difficulty

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent segments the host material design into modular anthracene core units with interchangeable aromatic substituents. This segmentation allows systematic optimization of efficiency parameters (electron mobility, hole mobility, triplet energy levels) while maintaining a consistent synthetic pathway. The modular approach enables targeted improvement of blue emission efficiency without requiring complete redesign of the molecular architecture

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention systematically varies key molecular parameters including molecular weight (optimized range provided), glass transition temperature (Tg ≥ 100°C), and substitution patterns to maximize device efficiency. Specific parameters are tuned to achieve optimal charge transport properties and triplet energy levels that enhance electroluminescence efficiency, particularly for blue emission applications

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If host materials with low glass-transition temperature are used, then vapour deposition is easier, but materials tend towards crystallisation instead of forming glass-like films

Engineering Contradiction:

Improveglass-like film stabilityVSAvoidvapour deposition process

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The patent fundamentally changes the glass transition temperature parameter by designing anthracene derivatives with Tg ≥ 100°C (preferably ≥ 150°C). This parameter change ensures that during vapour deposition at typical processing temperatures, the materials remain in a glassy state and form stable amorphous films rather than crystallizing. The elevated Tg is achieved through increased molecular weight and strategic placement of aromatic groups that enhance molecular rigidity and intermolecular interactions

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The molecular structure is designed beforehand to inherently resist crystallization during the vapour deposition process. The anthracene core with bulky aromatic substituents creates steric hindrance and complex molecular packing requirements that prevent crystallization kinetics from occurring during deposition. This structural cushioning ensures stable glass-like film formation even under varying deposition conditions

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS9017825B2Anthracene derivatives and their use in organic electroluminescent devices

Publication Date: 2015.04.28 MERCK PATENT GMBH

AI summary

The present invention relates to anthracene derivatives which are suitable for use in organic electroluminescent devices, and to organic electroluminescent devices containing these anthracene derivatives.