Two-Step UV Plasma Curing for OLED Encapsulation Films
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional ultraviolet curing processes for polymer films in OLED devices result in incomplete curing and high outgassing due to fast vitrification and the presence of unactivated photoinitiator molecules, leading to reduced environmental stability and performance issues.
Innovation Solution
A two-step curing process involving initial UV curing followed by UV plasma treatment to increase the degree of curing and reduce outgassing by immobilizing volatile photoinitiator species, resulting in higher cure degrees and lower outgassing levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional ultraviolet curing processes use high-intensity ultraviolet radiation, then the curing speed is improved, but the degree of curing is limited due to fast vitrification
Solution Approach 1:
The curing process is divided into two distinct stages: first, a conventional UV curing step that achieves partial curing and forms a stable film; second, a plasma treatment step that continues the curing process to achieve complete curing. This segmentation allows each stage to optimize for its specific function without the limitations of a single-step process.
Solution Approach 2:
The conventional UV curing step performs preliminary curing to form a stable polymeric film structure before the plasma treatment. This preliminary action creates a foundation that prevents outgassing during the subsequent plasma step while allowing the plasma to complete the curing process in the bulk material.
2Ease of manufacture
If photoinitiators are used to start monomer polymerization, then the curing reaction is initiated, but volatile species from photoinitiator degradation reduce film quality
Solution Approach 1:
The plasma treatment step converts the harmful volatile species into beneficial outcomes by providing energy that completes the polymerization reaction and immobilizes the photoinitiator fragments and degradation products within the crosslinked network, transforming them from harmful outgassing sources into stable components of the cured film.
Solution Approach 2:
The invention changes the energy input parameters from conventional UV radiation alone to a combination of UV radiation followed by plasma energy input. This parameter change enables complete polymerization and immobilization of volatile species without requiring modification of the photoinitiator chemistry.
3Device complexity
If a single-step UV curing process is used, then the manufacturing process is simple, but the cure degree remains incomplete and outgassing is high
Solution Approach 1:
The curing process is divided into two distinct stages: first, a conventional UV curing step that achieves partial curing and forms a stable film; second, a plasma treatment step that continues the curing process to achieve complete curing. This segmentation allows each stage to optimize for its specific function without the limitations of a single-step process.
4Speed
If high-intensity UV radiation is applied, then the curing speed increases, but vitrification occurs rapidly limiting further curing
Solution Approach 1:
The curing process is divided into two distinct stages: first, a conventional UV curing step that achieves partial curing and forms a stable film; second, a plasma treatment step that continues the curing process to achieve complete curing. This segmentation allows each stage to optimize for its specific function without the limitations of a single-step process.
Solution Approach 2:
The plasma treatment step continues the polymerization reaction that was initiated by the UV step, maintaining the useful action of curing without interruption. The plasma energy ensures complete conversion of remaining monomers and oligomers, achieving continuous and complete curing throughout the film thickness.
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 two-step process enhances the environmental stability and performance of polymeric films by achieving higher cure degrees and reducing outgassing, thereby improving the reliability and optical properties of OLED devices.
Implementation Method 1
The processes use an initiate curing step, following by a UV plasma treatment step, to achieve a higher degree of curing
Implementation Method 2
exposed to an ultraviolet plasma for a period sufficient to: (i) increase the cure degree in the cured polymeric film
Implementation Method 3
decrease the outgassing of fragments of cure initiator molecules from the cured polymeric film
Implementation Method 4
immobilizing volatile photoinitiator species
Data Source
AI summary
Methods for increasing the degree of curing and/or reducing the volatile photoinitiator concentration in cured polymeric film, and particularly in cured polymeric films in a multilayered thin film encapsulation stack are provided. Also provided are highly crosslinked and/or low-outgassing thin polymeric films and encapsulation stacks made using the methods.