Bank Structures with Fluorosurfactant for Uniform Film Formation
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Solution Overview
Problem
Existing methods for creating bank structures on substrates for organic electronic devices and color filter arrays face challenges in achieving uniform film formation and preventing solution spillage due to uncontrollable wetting and non-uniform thickness issues, particularly when using photoresist processes that affect wetting properties.
Innovation Solution
A photoresist formulation comprising a cresol novolak resin, a photoactive diazonaphthoquinone sulfonic ester of a polyhydroxybenzophenone compound with at least one free hydroxyl group, and a non-ionic urethane polyglycol fluorosurfactant is used to create bank structures, which are then patterned using photolithography and developed to define well regions, allowing for improved wetting properties and uniform deposition of active materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photoresist processes are used to create bank structures, then the manufacturing process is simple, but the wetting properties of the substrate are adversely affected and uniform film formation cannot be achieved
Solution Approach 1:
The patent extracts the wetting control function from the photoresist process by introducing a separate surfactant component. The surfactant is applied to the substrate before photoresist deposition, allowing wetting properties to be optimized independently from the patterning process. This separation enables uniform film formation without compromising the reliability of wetting properties.
Solution Approach 2:
The patent introduces a surfactant as an intermediary substance between the substrate and the photoresist layer. This surfactant layer mediates the interaction between organic solutions and the substrate surface, ensuring optimal wetting for uniform film formation while being compatible with subsequent photoresist processing steps.
2Reliability
If the contact angle of the bank structure is increased to prevent solution spillage, then solution containment is improved, but the process window for printing formulation is reduced
Solution Approach 1:
The patent modifies the surface energy parameters of the bank structure by incorporating fluorinated compounds and surfactants. This changes the contact angle characteristics to achieve an optimal balance: high enough to prevent solution spillage during deposition, but not so high as to eliminate the process window for formulation printing. The parameter optimization allows both solution containment and printing capability to coexist.
3Manufacturing precision
If shadow masking with vacuum deposition is used, then precise pattern definition is achieved, but material waste is high and manufacturing cost increases
Solution Approach 1:
The patent replaces the mechanical shadow masking system with a chemical patterning approach using photoresist and surfactant layers. Instead of using physical masks that block deposition, the method uses selective wetting and surface energy control to guide solution-based material deposition only into desired well regions, eliminating material waste associated with shadow masking while maintaining precise pattern definition.
4Manufacturing precision
If the substrate contact angle is decreased to improve organic material spread, then film uniformity is improved, but solution spillage risk increases
Solution Approach 1:
The patent applies different surface properties to different locations: the substrate is treated to have low contact angle for optimal organic material spread and film uniformity, while the bank structure walls are treated with fluorinated compounds to have high contact angle for solution containment. This local differentiation of surface quality allows both film uniformity and spillage prevention to be achieved simultaneously in their respective locations.
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 method provides high-quality bank structures with enhanced wetting properties, minimizing spillage and ensuring uniform film formation within the active areas, while also enabling cost-effective and high-output manufacturing of organic electronic devices and color filter arrays.
Implementation Method 1
a photoactive diazonaphthoquinone sulfonic ester of a polyhydroxybenzophenone compound with at least one free hydroxyl group
Implementation Method 2
a non-ionic urethane polyglycol fluorosurfactant
Implementation Method 3
heating the coated substrate to remove any solvent
Data Source
AI summary
A photolithiographic method for fabricating bank structures with improved non-wetting properties to form well regions on a substrate using a photoresist composition comprising a cresol novolak resin, a photoactive diazonaphthoquinone sulfonic ester of a polyhydroxybenzophenone compound with at least one free hydroxyl group, and a non-ionic urethane polyglycol fluorosurfactant. Inkjet methods can be used to deposit active materials into the well areas. Color filter arrays and optoelectronic devices such as OLED devices can be made by this method.