Electric Field Drying for OLED Inkjet Printing Uniformity
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Solution Overview
Problem
Inkjet printing of OLED displays faces challenges in achieving a uniform film thickness and preventing the coffee ring effect due to solvent vaporization, requiring complex air-evacuation processes and specific solvents.
Innovation Solution
A method involving the formation of an electric field on the pixel electrode layer to dry the light-emitting functional layer, which fixes charged groups and inhibits solvent-driven movement, thereby ensuring a uniform film thickness and simplifying the drying process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If vacuum drying and heating methods are used to remove solvent during inkjet printing, then the solvent can be effectively evaporated, but a complicated air-evacuation process is required and special solvents must be selected to suppress coffee ring effect
Solution Approach 1:
The patent replaces the mechanical vacuum drying system with an electric field-based drying method. By applying an electric field between the pixel electrode and a conductive member, solvent molecules are directly driven to evaporate without requiring complex vacuum equipment. The electric field strength is controlled to achieve uniform drying while preventing coffee ring effect, thus simplifying the device structure while maintaining film quality.
Solution Approach 2:
The patent changes the drying mechanism from thermal/pressure-based (vacuum heating) to electric field-based. By adjusting electric field strength, voltage, and frequency parameters, the drying process achieves effective solvent removal without the need for special solvents or complicated air-evacuation systems, resolving the contradiction between film quality and process complexity.
2Quantity of substance
If conventional drying methods are used, then solvent can be removed, but coffee ring effect appears in the light-emitting functional layer
Solution Approach 1:
The patent replaces conventional thermal drying with electric field-driven drying. The electric field directly acts on polar solvent molecules, causing them to align and evaporate uniformly across the film surface. This prevents the coffee ring effect where solvent would otherwise concentrate at the edges during evaporation, achieving both complete solvent removal and uniform film thickness.
Solution Approach 2:
The electric field serves as an intermediary mechanism between the power source and the solvent molecules. By applying voltage between the pixel electrode and conductive member, the electric field mediates the drying process, ensuring uniform solvent removal without the non-uniform concentration patterns that cause coffee ring effect in conventional drying methods.
3Manufacturing precision
If special solvents are selected to suppress coffee ring effect, then film quality can be maintained, but the process requires specific solvent selection and control
Solution Approach 1:
The patent replaces solvent-based control mechanisms with electric field-based control. Instead of carefully selecting and managing special solvents to prevent coffee ring effect, the invention uses an electric field to directly control the drying process. This eliminates the need for complex solvent selection and control procedures, making the manufacturing process easier while maintaining high film quality.
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 prevents the coffee ring effect and achieves high-quality films by stabilizing the light-emitting functional layer during solvent evaporation, simplifying the vacuum drying process and improving processing efficiency.
Implementation Method 1
forming an electric field for drying on the pixel electrode layer
Implementation Method 2
forming an electric field for drying on the pixel electrode layer... drying the substrate to be dried... evacuating the chamber and discharging a solvent in the solution of the light-emitting functional layer under the electric field for drying
Implementation Method 3
evacuating the chamber and discharging a solvent in the solution of the light-emitting functional layer
Implementation Method 4
discharging a solvent in the solution of the light-emitting functional layer under the electric field for drying to form a light-emitting functional layer
Data Source
AI summary
A fabrication method of a display panel and a drying device are provided by the present application. In the display panel of the present application, an electrical field for drying on a pixel electrode layer is used to fix charged groups in a solution of a light-emitting functional layer, which prevents a solvent from driving the movement of the charged groups when the solvent is volatilized, thereby obtaining a light-emitting functional layer with a uniform film thickness. Moreover, the use of the electric field for drying fixes the charged groups so that a drying treatment is performed without strict pumping control during the solvent volatilization process.