Inkjet Organic Light-Emitting Element Ink Drop Flight Control
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Solution Overview
Problem
The challenge in manufacturing organic light-emitting elements using the application method is achieving uniform film thickness and shape of the organic light-emitting layer, as the flight characteristics of ink drops are difficult to control due to unclear correlations among ink properties such as density, surface tension, viscosity, and droplet diameter, and are further influenced by nozzle diameter and ejection speed.
Innovation Solution
A method involving ink with a weight-average molecular weight between zero and 400,000, where the Ohnesorge number reciprocal (Z) and ejection speed (V) are within specific ranges, allowing for precise estimation of flight characteristics, ensuring accurate and efficient formation of the organic light-emitting layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the application method is used to manufacture organic light-emitting elements, then mass production efficiency is improved and vacuum chamber processes are eliminated, but the flight characteristics of ink drops become difficult to control due to multiple variable parameters
Solution Approach 1:
The invention changes the parameters of ink properties (density, surface tension, viscosity) and ejection conditions (nozzle diameter, ejection speed) to achieve desired flight characteristics. By systematically adjusting these parameters within specific ranges, the patent enables controlled ink drop delivery while maintaining mass production efficiency through the application method
Solution Approach 2:
The invention introduces feedback mechanisms to evaluate and adjust flight characteristics. By measuring actual ink drop flight behavior and comparing it with target characteristics, the system can modify ink formulation or ejection parameters to achieve uniform film deposition, thereby resolving the control difficulty while preserving productivity benefits
2Manufacturing precision
If multiple ink properties (density, surface tension, viscosity) and ejection parameters (nozzle diameter, ejection speed) are varied to control flight characteristics, then accurate ink drop placement can be achieved, but the time required to determine optimal conditions increases significantly
Solution Approach 1:
The invention performs preliminary establishment of relationships between ink properties, ejection parameters, and flight characteristics. By pre-determining optimal parameter combinations and their effects on ink drop behavior, the system reduces the time required for condition determination during actual production while maintaining accurate ink drop placement
Solution Approach 2:
The invention systematically varies parameters within defined ranges to establish optimal conditions. By identifying specific ranges for density, surface tension, viscosity, nozzle diameter, and ejection speed that produce desired flight characteristics, the patent reduces the search space and accelerates condition determination while ensuring precise ink drop placement
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
This approach enables easy and accurate estimation of flight characteristics, leading to the efficient manufacturing of organic light-emitting elements with excellent light-emitting characteristics by controlling the flight characteristics of ink drops using two variables, Z and V.
Implementation Method 1
preparing ink including functional material as a material for a functional layer and a solvent dissolving the functional material
Implementation Method 2
causing the inkjet device to eject a drop of the ink onto the base layer of the substrate
Implementation Method 3
forming the functional layer by drying the ink ejected onto the base layer of the substrate
Implementation Method 4
organic light-emitting elements, which have recently been studied and developed, are light-emitting elements making use of the phenomenon of electroluminescence occurring in functional material
Data Source
AI summary
To provide a method of efficiently manufacturing an organic light-emitting element with excellent light-emitting characteristics by application, the method includes: preparing ink and filling an inkjet device having an ink ejection nozzle with the ink; preparing a substrate having a base layer including a first electrode; and positioning the inkjet device above the substrate, and causing the inkjet device to eject a drop of the ink onto the base layer, wherein, in the preparation of the ink, a value Z denoting a reciprocal of the Ohnesorge number Oh determined by density ρ (g/dm3), surface tension γ (mN/m), and viscosity η (mPa·s) of the ink and a diameter r (mm) of the ink ejection nozzle satisfies Formula 1, in the ejection of the drop of the ink, speed V (m/s) of the ejected drop satisfies Formula 2, and the value Z and the speed V (m/s) satisfy Formula 3.