Organic Light-Emitting Device Solvent Composition for Thin Film Uniformity
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Solution Overview
Problem
Existing methods for forming organic light-emitting devices using multiple solvents with similar boiling points result in surface roughness and defects due to concurrent evaporation, leading to suboptimal thin film uniformity and increased surface defects.
Innovation Solution
A composition comprising n kinds of solvents, where the solvent with the highest boiling point has a viscosity four or more times that of the second highest boiling point, allowing for gradual evaporation and reducing surface roughness, is used to form an organic light-emitting device, with the solvent having the highest boiling point being represented by a specific compound formula.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple solvents with similar boiling points are used for forming organic light-emitting devices, then the device can be manufactured with standard processes, but surface roughness and defects occur due to concurrent evaporation
Solution Approach 1:
The patent changes the physical parameter of solvent boiling points to resolve the contradiction. By selecting solvents with significantly different boiling points (first solvent: 180-250°C, second solvent: 80-150°C), the evaporation occurs sequentially rather than concurrently, improving thin film uniformity while maintaining manufacturing feasibility through solution processing
Solution Approach 2:
The patent introduces dynamic control of the evaporation process through temperature management. The drying process is conducted in two stages: first at a temperature below the boiling point of the second solvent to allow complete evaporation of the first solvent, then at a higher temperature to evaporate the second solvent. This dynamic temperature control ensures sequential evaporation and prevents surface defects
2Device complexity
If multiple solvents with similar boiling points are used, then the formulation is simple, but surface defects increase due to concurrent evaporation
Solution Approach 1:
The patent changes the boiling point parameter differentiation between solvents to resolve the contradiction. By ensuring the boiling point difference is at least 30°C (first solvent: 180-250°C, second solvent: 80-150°C), the evaporation processes are separated in time, preventing surface defects while maintaining a relatively simple two-solvent formulation
Solution Approach 2:
The patent applies preliminary action by first allowing the high-boiling-point solvent to completely evaporate before initiating evaporation of the low-boiling-point solvent. This sequential approach, controlled through staged temperature drying, prevents the harmful concurrent evaporation effect while keeping the formulation simple
3Speed
If solvents with similar boiling points are used, then the evaporation process is fast, but thin film uniformity deteriorates due to concurrent evaporation
Solution Approach 1:
The patent segments the evaporation process into two distinct stages corresponding to two different solvent evaporation phases. The drying process is divided into: (1) first drying stage at temperature below the boiling point of the second solvent to evaporate the first solvent, and (2) second drying stage at higher temperature to evaporate the second solvent. This segmentation prevents concurrent evaporation and improves thin film uniformity
Solution Approach 2:
The patent changes the temperature parameter dynamically during the evaporation process. By controlling the drying temperature to first be below the boiling point of the second solvent and then increase to evaporate it, the process achieves sequential evaporation. This parameter control optimizes both evaporation efficiency and thin film uniformity
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 improves thin film uniformity and reduces surface defects, enhancing the overall performance and quality of the organic light-emitting device by controlling the evaporation process and viscosity of the solvents.
Implementation Method 1
a solvent (Sv1) having the highest boiling point among the n kinds of solvent and a solvent (Sv2) having the second highest boiling point among the n kinds of solvent satisfy Equation 1... allowing for gradual evaporation and reducing surface roughness
Data Source
AI summary
Provided are a composition for forming an organic light-emitting device, a method of preparing an organic light-emitting device, and an organic light-emitting device. The method of preparing an organic light-emitting device includes: forming an organic layer including an emission layer on a first electrode, wherein the forming of the organic layer includes performing a solution process using a composition for forming an organic light-emitting device, the composition for forming an organic light-emitting device includes n kinds of solvent, a solvent (Sv1) having the highest boiling point among the n kinds of solvent and a solvent (Sv2) having the second highest boiling point among the n kinds of solvent satisfy Equation 1, n is an integer from 2 to 10, and the solvent (Sv1) having the highest boiling point among the n kinds of solvent is a compound represented by Formula 1.