Sterically Hindered Boron-Nitrogen Emitters for Blue OLEDs
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Solution Overview
Problem
Current OLEDs, particularly blue-emitting ones, face challenges in achieving high efficiency, long lifetime, and pure color emission, with existing emitters and host compounds not meeting the requirements for broad commercial use in display devices or light sources.
Innovation Solution
Development of novel compounds of formula (1) that exhibit prompt fluorescence and/or delayed fluorescence, specifically designed as sterically hindered fluorescent emitters for use in hyperfluorescent or hyperphosphorescent systems, suitable for both vacuum processing and solution-based processing, with specific structural features allowing for improved solubility and molecular orientation in films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional emitters and host compounds are used in blue-emitting OLEDs, then device structure and processing are simpler, but efficiency, lifetime, and color purity are insufficient for broad commercial use
Solution Approach 1:
The patent employs composite material design by combining specific emitter compounds (formula 1) with carefully selected host compounds (formula 2 or 3) to create an emitting layer with optimized properties. The emitter contains boron and nitrogen atoms in a specific molecular architecture that provides both high efficiency and long lifetime, while the host compound structure is designed to complement the emitter's properties, creating a synergistic system that achieves commercial-grade performance without excessive complexity
Solution Approach 2:
The patent applies local quality optimization by designing the emitter molecule with specific functional groups positioned at particular locations (R1-R6 substituents on the boron-containing core) to enhance electron-hole recombination at the emission site while maintaining overall molecular stability. The host compound also features localized structural elements (Ar1-Ar6 aromatic groups with specific substituents) that create optimal local environments for exciton management and energy transfer, improving device performance at critical locations without redesigning the entire system
2Manufacturing precision
If blue-emitting OLEDs use existing emitter materials, then development time is reduced, but color purity and efficiency remain insufficient
Solution Approach 1:
The patent achieves superior color purity by precisely controlling molecular parameters of the emitter compound, including the specific arrangement of boron and nitrogen atoms, the types of aromatic substituents (R1-R6), and their positions on the molecular core. These parameter optimizations narrow the emission spectrum and enhance the dominant blue wavelength output. The host compound parameters (aromatic groups Ar1-Ar6, substituent patterns) are similarly tuned to match the emitter's energy levels, ensuring efficient energy transfer and minimal spectral broadening, thereby achieving high color purity without requiring excessive emitter material concentration
3Productivity
If sterically hindered fluorescent emitters are designed for hyperfluorescent systems, then efficiency and color purity improve, but molecular complexity and synthesis difficulty increase
Solution Approach 1:
The emitter molecule is segmented into distinct functional modules: a boron-containing core structure (providing the fluorescent emission center), aromatic substituent groups (R1-R6) that provide steric hindrance and tune emission properties, and linkers that connect these elements. This modular segmentation allows independent optimization of each component's function while simplifying the overall design process. The host compound is similarly segmented into a core aromatic structure with peripheral substituents, enabling systematic optimization of host-guest interactions without requiring complete redesign of the entire molecular system
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 compounds achieve enhanced efficiency, prolonged lifetime, and improved color purity in OLEDs, addressing the limitations of existing blue-emitting materials by optimizing the emitter and host compound selection in electronic devices.
Implementation Method 1
In the last decade, compounds which exhibit thermally activated delayed fluorescence (TADF) (e.g. H. Uoyama et al., Nature 2012, vol. 492, 234) have also been intensively researched. TADF materials are, in general, organic materials in which the energy gap between the lowest triplet state T1 and the first excited singlet state S1 is sufficiently small so that the S1 state is thermally accessible from the T1 state.
Implementation Method 2
Recently, polycyclic aromatic compounds comprising Boron and Nitrogen atoms have been described (for example in US2015/0236274A1, CN107501311A, WO2018/047639A1). These compounds can be used as fluorescent emitters, where the fluorescent emission is mainly prompt fluorescence or as TADF compounds.
Data Source
AI summary
The present invention relates to compounds of the formula (1) which are suitable for use in electronic devices, in particular organic electroluminescent devices, and to electronic devices which comprise these compounds.