OLED Host Material Combinations for Balanced Charge Transport
Solution Overview
Problem
Existing organic electroluminescent devices face challenges in achieving high luminous efficiency and long lifespan due to imbalances in hole and electron mobilities, necessitating improved host materials.
Innovation Solution
A combination of compounds represented by formulas 1 and 2, comprising specific nitrogen-containing moieties, is introduced to balance hole and electron mobilities, enhancing exciton formation and improving the efficiency and lifespan of OLEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a compound with very deep HOMO is used as host material, then electron mobility is improved, but hole mobility becomes unbalanced and luminous efficiency deteriorates
Solution Approach 1:
The patent employs composite host materials comprising both a first host compound (Formula 1) and a second host compound (Formula 2). The first host provides deep HOMO and fast electron mobility, while the second host contributes fast hole mobility. This composite approach balances the charge carrier mobilities to achieve high luminous efficiency and long device lifespan.
2Reliability
If phosphorous materials are used to achieve high luminous efficiency, then lifespan characteristics are compromised
Solution Approach 1:
The patent changes the chemical and physical parameters of the host materials by selecting compounds with specific structural features: Formula 1 compounds provide deep HOMO levels and fast electron mobility, while Formula 2 compounds provide fast hole mobility. This parameter optimization enables high luminous efficiency without sacrificing device lifespan.
3Device complexity
If a single host material is used, then device complexity is reduced, but performance optimization is limited
Solution Approach 1:
The patent utilizes a composite host system with two specific compounds (Formula 1 and Formula 2) that work synergistically. This composite approach optimizes both luminous efficiency and lifespan while maintaining practical device complexity through well-defined molecular structures and preparation methods.
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 combination of host materials results in higher luminous efficiency and extended lifespan of organic electroluminescent devices, suitable for display and lighting applications.
Implementation Method 1
The compound of formula 1 of the present disclosure provides slow hole mobility due to very deep HOMO (highest occupied molecular orbital) and fast electron mobility due to a nitrogen-containing moiety
Implementation Method 2
high efficiency and long lifespan due to increase of exciton formation in the light-emitting layer could be accomplished by using the combination of the compounds of formulas 1 and 2 in an OLED
Data Source
AI summary
The present disclosure relates to a plurality of host materials comprising a first host material comprising a compound represented by the following formula 1, and a second host material comprising a compound represented by the following formula 2, and an organic electroluminescent device comprising the same. By comprising a specific combination of compounds as a host material, it is possible to provide an organic electroluminescent device having higher luminous efficiency and/or improved lifespan characteristics compared to conventional organic electroluminescent devices.