Cyclic Siloxane Compound Purification for Organic EL Devices
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Solution Overview
Problem
High molecular weight complex compounds used in organic electroluminescence devices have limited purity due to difficulties in purification methods, such as reprecipitation and column chromatography, which affects their luminous efficiency and suitability for large-area applications.
Innovation Solution
Development of cyclic siloxane compounds with specific luminescent and charge-transporting groups that can be purified to high purity using column chromatography, enabling their use in luminescent layers of organic electroluminescence devices for large-area applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If reprecipitation purification is used for high molecular weight compounds, then the purification process is simple, but the purity is insufficient
Solution Approach 1:
The patent changes the chemical structure parameters of the siloxane compound by introducing specific substituents (aromatic hydrocarbon groups, heterocyclic groups) and controlling the cyclic structure (n=2-100), which fundamentally alters the compound's interaction with silica gel. This structural modification enables the compound to be purified by column chromatography, transforming the purification approach from reprecipitation to chromatography, thereby simultaneously achieving high purity and reasonable process simplicity.
2Manufacturing precision
If column chromatography is used for high molecular weight compounds, then the purity can be improved, but the compound is tightly adsorbed to the filler and cannot be purified
Solution Approach 1:
The patent modifies the chemical structure parameters of the siloxane compound by introducing specific substituents (aromatic hydrocarbon groups, heterocyclic groups) and controlling the cyclic structure, which fundamentally changes the compound's adsorption characteristics on silica gel. This structural modification reduces the adsorption strength to an appropriate level, enabling successful column chromatography purification while maintaining high purity.
Solution Approach 2:
The patent creates a composite structure where the siloxane backbone is combined with specific aromatic hydrocarbon groups and heterocyclic groups. This composite molecular structure provides both the high molecular weight characteristics needed for solution processing and the appropriate adsorption properties for column chromatography purification, resolving the contradiction between purity and process feasibility.
3Reliability
If vacuum deposition is used for mass production, then the luminous efficiency can be maintained, but the method is not suitable for large-sized panels
Solution Approach 1:
The patent changes the physical state parameter of the luminescent material from low molecular weight (requiring vacuum deposition) to high molecular weight cyclic siloxane compounds that can be processed as solutions. This parameter change enables the use of solution-based fabrication methods like ink-jetting and printing, which are suitable for large-area panels while maintaining luminous efficiency through the compound's inherent phosphorescent properties.
Solution Approach 2:
The patent replaces the vacuum deposition mechanical system with solution-based deposition methods (ink-jetting, printing). The high molecular weight cyclic siloxane compound serves as a vehicle to deliver the luminescent material in solution form, substituting the vacuum evaporation process with liquid-phase deposition, thereby enabling large-area fabrication while preserving luminous efficiency.
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 cyclic siloxane compounds achieve high luminous efficiency and can be easily purified, making them suitable for large-sized devices and mass production, overcoming the limitations of traditional purification methods.
Implementation Method 1
purification process of the high molecular weight compound is limited to, for example, reprecipitation purification... when a high molecular weight compound is purified by the column chromatography using a common filler such as silica gel or alumina
Implementation Method 2
material development using a phosphorescent compound having high luminous efficiency has been actively performed
Data Source
AI summary
The present invention provides a compound that can be readily purified and an organic EL device having a luminescent layer including the compound. In particular, the present invention provides a cyclic siloxane compound represented by Formula (1) below:wherein, in Formula (1), R1 and R2 are each independently a luminescent monovalent group, a charge-transporting monovalent group, or another substituent; at least one of R1 and R2 is the charge-transporting monovalent group or the luminescent monovalent group; and n is an integer of 2 to 100, and an organic EL device having luminescent layer containing the compound.