Polycyclic Aromatic Host Compounds for Solution-Processed OLEDs
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Solution Overview
Problem
Current wet film formation methods for organic electroluminescent elements face challenges with low solubility and film formability of host and dopant compounds, leading to impurities and poor quality coatings, which hinder achieving performance comparable to vacuum deposition methods.
Innovation Solution
A polycyclic aromatic compound with high triplet energy, linked by a boron atom or oxygen, and functional groups is used as a host in a light-emitting layer-forming composition, combined with a phosphorescent or thermally activated delayed fluorescent dopant and suitable organic solvents, to enhance solubility, film formability, and in-plane orientation, enabling efficient and stable organic EL element production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet film formation method is used, then manufacturing cost is reduced and continuous manufacturing is possible, but film quality and uniformity deteriorate due to impurities and poor solubility
Solution Approach 1:
The patent changes the chemical parameters of the host and dopant compounds by introducing specific molecular structures with high solubility characteristics. This allows the wet film formation method to achieve both low cost and high film quality by fundamentally altering the material properties rather than the process parameters
Solution Approach 2:
The patent creates composite ink compositions by combining specifically designed host compounds with dopant compounds in optimized ratios. This composite approach enables the formulation to achieve superior solubility, film uniformity, and functional performance simultaneously, resolving the contradiction between ease of manufacture and manufacturing precision
2Productivity
If wet film formation method is used, then continuous manufacturing is enabled, but lamination becomes difficult and film uniformity deteriorates
Solution Approach 1:
The patent modifies the chemical parameters of the coating materials to achieve high solubility and low viscosity, which enables continuous manufacturing while maintaining excellent film uniformity. The modified compounds can be processed in solution form without compromising quality
Solution Approach 2:
The patent achieves uniform film formation by ensuring homogeneous distribution of dopant compounds within the host matrix at the molecular level. This local uniformity throughout the entire coating solution translates to macroscopic film uniformity during continuous manufacturing processes
3Quantity of substance
If conventional host and dopant compounds are used in wet film formation, then solubility is low, but this leads to poor film formability and impurity formation
Solution Approach 1:
The patent fundamentally changes the chemical parameters of the host and dopant compounds by introducing specific functional groups and molecular structures. These parameter changes dramatically improve solubility in common solvents while simultaneously enhancing film formability and eliminating impurity formation
Solution Approach 2:
The patent develops ink compositions that replicate the high-quality film characteristics of vacuum deposition methods but through a different chemical pathway. By copying the desired film properties and achieving them through solution processing, the method attains both good solubility and reliable film formability
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 solution provides a light-emitting layer-forming composition with improved solubility, film formability, and in-plane orientation, resulting in organic EL elements with enhanced efficiency, lifetime, and reduced driving voltage, overcoming the limitations of traditional wet film formation methods.
Implementation Method 1
a light emitting layer-forming composition containing a polycyclic aromatic compound having high triplet energy (ET)
Implementation Method 2
ink compositions utilizing phosphorescent light
Implementation Method 3
ink compositions utilizing phosphorescent light or thermally activated delayed fluorescence
Data Source
AI summary
The present invention addresses the problem of providing a polycyclic aromatic compound which has improved solubility in solvents, film formability, wet coatability and in-plane orientation. The above-described problem is solved by a composition for forming a light emitting layer, which contains, as a first component, at least one compound selected from the group consisting of compounds represented by general formula (A-1) and compounds represented by general formula (A-2), as a second component, at least one compound that has a triplet energy (ET) of 1.8-3.0 eV, and as a third component, at least one organic solvent.In the formulae, R represents a hydrogen atom, an aryl group, a heteroaryl group, a diarylamino group, a diheteroarylamino group or an aryl heteroarylamino group.