Ester Solvents with Non-Aromatic Cycles for OLED Inkjet Printing
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Solution Overview
Problem
The challenge in organic electronic devices, particularly in inkjet printing, is the complex interplay of solvent parameters that affects the deposition and drying processes, making it difficult to achieve uniform and high-performance organic semiconductor layers.
Innovation Solution
A formulation using an ester solvent with a non-aromatic cyclic alkyl or alkenyl group, specifically defined by General Formula (I) or (II), is employed, which includes organic functional materials like conductors, semiconductors, and photoactive compounds, to facilitate controlled deposition and uniform layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional solvents are used in inkjet printing for OLEDs, then deposition and drying processes can be performed, but achieving uniform and high-performance organic semiconductor layers becomes difficult due to complex interplay of solvent parameters
Solution Approach 1:
The patent applies parameter changes by systematically modifying key solvent properties including selecting esters with specific boiling points (100-300°C), viscosities (0.5-5 cP), and surface tensions (15-35 mN/m). These controlled parameter changes optimize the balance between deposition uniformity and drying characteristics, resolving the contradiction between layer uniformity and process complexity.
Solution Approach 2:
The patent employs composite material strategies by formulating ink compositions that combine organic semiconductor materials with carefully selected ester solvents and additional additives. This composite approach creates synergistic effects where the solvent system collectively manages multiple parameters (solubility, evaporation rate, surface tension) to achieve uniform layer formation while simplifying overall process control.
2Manufacturing precision
If solvent parameters are optimized for good layer properties, then deposition uniformity improves, but achieving good device performances becomes challenging due to multiple influencing factors
Solution Approach 1:
The patent systematically adjusts solvent parameters including boiling point (100-300°C), viscosity (0.5-5 cP), and surface tension (15-35 mN/m) to simultaneously optimize both layer properties and device performance. This multi-parameter optimization ensures that improved deposition uniformity translates directly to enhanced device reliability and performance.
Solution Approach 2:
The patent implements feedback mechanisms by evaluating device performance metrics and using this information to refine solvent selection and formulation parameters. This iterative optimization process ensures continuous improvement of both layer quality and device performance, addressing the contradiction between manufacturing precision and reliability.
3Ease of manufacture
If inkjet printing is used for OLED fabrication, then cost savings and scale-up possibilities are achieved, but homogeneous deposition of inks on substrate is difficult to obtain
Solution Approach 1:
The patent optimizes ink formulation parameters including solvent viscosity (0.5-5 cP), surface tension (15-35 mN/m), and composition to ensure homogeneous deposition in inkjet printing. These parameter adjustments maintain the cost-effectiveness and scalability of inkjet printing while achieving the required deposition uniformity for high-quality OLED fabrication.
Solution Approach 2:
The patent develops composite ink formulations combining organic semiconductors with optimized ester solvent systems and functional additives. This composite approach enhances deposition homogeneity while preserving the economic advantages of inkjet printing, resolving the contradiction between ease of manufacture and manufacturing precision.
4Manufacturing precision
If multiple parameters are adjusted for homogeneous deposition, then inkjet printing performance improves, but the number of parameters to identify and adjust increases
Solution Approach 1:
The patent identifies and optimizes a focused set of critical parameters including solvent boiling point (100-300°C), viscosity (0.5-5 cP), and surface tension (15-35 mN/m). By concentrating on these key parameters rather than all possible variables, the patent achieves homogeneous deposition while managing overall system complexity effectively.
Solution Approach 2:
The patent employs composite material formulations where the solvent system collectively manages multiple deposition parameters. This approach allows homogeneous inkjet printing to be achieved through coordinated optimization of solvent properties rather than adjusting numerous independent parameters, thereby improving deposition quality while controlling process complexity.
Data Source
AI summary
The present invention relates to formulations for the preparation of organic electronic devices (OLEDs) which comprise at least one specific ester solvent containing a non aromatic cycle and at least one organic functional material selected from organic conductors, organic semiconductors, organic fluorescent compounds, organic phosphorescent compounds, organic light-absorbent compounds, organic light-sensitive compounds, organic photosensitisation agents and other organic photoactive compounds, selected from organometallic complexes of transition metals, rare earths, lanthanides and actinides.