Organic Electroluminescent Compound with High Glass Transition Temperature
Solution Overview
Problem
Existing organic electroluminescent devices face challenges with quantum efficiency and lifespan due to thermal stress and imbalanced hole-electron charge, necessitating the development of improved hole transport materials.
Innovation Solution
An organic electroluminescent compound with a distorted structure is developed, which achieves a higher glass transition temperature (Tg) of 130°C or higher, enhancing thermal stability and charge mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hole transport materials (CuPc, NPB, TPD, MTDATA) are used, then hole transport efficiency is achieved, but thermal stress occurs between anode and hole injection layer under high current, reducing device lifespan
Solution Approach 1:
The patent changes the glass transition temperature parameter of the hole transport material from conventional values to 130°C or higher. This parameter change reduces thermal stress between the anode and hole injection layer under high current driving conditions, thereby extending device lifespan while maintaining hole transport efficiency
Solution Approach 2:
The patent employs a composite molecular structure combining a dibenzofuran or dibenzodioxole core with specific substituent groups (formula 1). This composite structure achieves both high glass transition temperature (≥130°C) for reduced thermal stress and appropriate hole mobility for efficient charge transport
2Reliability
If organic material with very high hole mobility is used in hole injection layer, then hole transport is efficient, but hole-electron charge balance is broken and quantum yield decreases
Solution Approach 1:
The patent optimizes the hole mobility parameter to an appropriate range rather than maximizing it. By controlling hole mobility to match electron mobility, the patent achieves balanced charge transport and improved quantum yield (cd/A) while preventing charge balance disruption
3Temperature
If molecular weight is increased by bonding substituents to raise glass transition temperature, then thermal stability improves, but deposition temperature of organic compound increases
Solution Approach 1:
The patent uses a composite molecular structure with dibenzofuran or dibenzodioxole core that intrinsically provides high glass transition temperature (≥130°C) without requiring excessive molecular weight increase. This composite approach achieves thermal stability while maintaining manageable deposition temperatures for device fabrication
4Reliability
If thin film material has low glass transition temperature, then deposition is easier, but film is easily changed by heat during device operation, decreasing charge mobility
Solution Approach 1:
The patent changes the glass transition temperature parameter to 130°C or higher, ensuring the thin film remains stable and maintains its charge transport properties during device operation. This parameter optimization prevents film degradation from operational heat while preserving charge mobility
Data Source
AI summary
The present disclosure relates to an organic electroluminescent compound represented by formula 1 and an organic electroluminescent device comprising the same. By comprising the organic electroluminescent compound of the present disclosure, an organic electroluminescent device having improved driving voltage and/or luminous efficiency characteristics can be provided.