Phosphorescent OLED Host Materials for Low-Concentration Lifetime
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Solution Overview
Problem
There is a need for improved matrix materials in phosphorescent OLEDs, particularly to enhance device lifetime, especially at low to moderate emitter concentrations.
Innovation Solution
Combining at least one compound of formula (1a) or (1b) as a first host material with a hole-transporting compound in the light-emitting layer of an organic electroluminescent device, using specific diazadibenzofuran or diazadibenzothiophene derivatives in combination with other host materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If conventional matrix materials are used in phosphorescent OLEDs, then the device can operate, but the lifetime is limited especially at low to moderate emitter concentrations
Solution Approach 1:
The patent employs composite host materials comprising diazadibenzofuran or diazadibenzothiophene derivatives combined with other matrix materials (such as carbazole derivatives, dibenzofuran derivatives, or triphenylene derivatives). This composite approach synergistically improves device lifetime and performance stability, particularly at low to moderate emitter concentrations (3-20%), by combining the advantageous properties of different material classes for enhanced triplet energy levels, charge transport, and structural stability.
Solution Approach 2:
The patent modifies the molecular structure of host materials by introducing specific diazadibenzofuran or diazadibenzothiophene core structures with varying substituents (Ar, Ar1, Ar2, Ar3 groups) and linkers (L1). These structural parameter changes optimize triplet energy levels, HOMO-LUMO gaps, and charge transport properties, thereby extending device lifetime while maintaining reliability at low emitter concentrations.
2Loss of energy
If phosphorescent OLEDs are operated at low to moderate emitter concentrations (3-20%), then the device efficiency is improved, but the lifetime becomes limited
Solution Approach 1:
The composite host system combines diazadibenzofuran/diazadibenzothiophene derivatives with auxiliary matrix materials to achieve synergistic effects that maintain high energy efficiency at low emitter concentrations (3-15%) while simultaneously extending device lifetime. The composite structure provides sufficient triplet energy levels and improved charge distribution to prevent efficiency loss and degradation.
Solution Approach 2:
The diazadibenzofuran/diazadibenzothiophene derivative acts as an intermediary host material that mediates between the phosphorescent emitter and the auxiliary matrix material, facilitating efficient energy transfer and charge distribution. This intermediary role enables the system to maintain high quantum efficiency while protecting the emitter from degradation, thereby extending device lifetime at low concentrations.
3Device complexity
If conventional matrix materials are used, then the device structure is simple, but the lifetime and efficiency show room for improvement
Solution Approach 1:
The patent introduces composite matrix materials based on diazadibenzofuran or diazadibenzothiophene derivatives combined with conventional matrix materials (carbazole derivatives, dibenzofuran derivatives, triphenylene derivatives, etc.). This composite approach systematically improves device lifetime and efficiency while maintaining reasonable structural complexity through well-defined molecular architectures and systematic substituent patterns.
Data Source
AI summary
The present invention relates to diazadibenzofuran derivatives and diazadibenzothiophene derivatives and to electronic devices containing these compounds, in particular organic electroluminescent devices containing these compounds in the form of matrix materials, optionally in combination with a further matrix material and suitable phosphorescent emitters, and suitable mixtures and formulations of said compounds.