Multilayer Barrier Coatings for Flexible Optoelectronics
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Solution Overview
Problem
Current barrier coatings for organic optoelectronic devices, such as organic photovoltaic devices on flexible plastic substrates, face limitations due to pinholes and defects in inorganic layers, leading to water and oxygen permeation, which reduces device lifetime and requires high-cost, rigid substrates for protection.
Innovation Solution
A method involving the deposition of multilayer coatings using initiated chemical vapor deposition (iCVD) and plasma-enhanced chemical vapor deposition (PECVD) techniques, alternating organic and inorganic layers to decouple defects, fill pores, and smooth the substrate surface, enhancing barrier properties and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single thin inorganic layer is used as barrier coating, then the theoretical permeability coefficient is low enough to serve as perfect barrier, but residual permeation through defects and pinholes limits the minimum WVTR achievable to 10^-2 g/m2/day
Solution Approach 1:
The barrier coating is segmented into multiple alternating inorganic and organic layers. Each inorganic layer provides barrier function while organic layers fill defects and pinholes from adjacent inorganic layers, collectively achieving superior barrier performance that cannot be obtained by a single inorganic layer alone.
Solution Approach 2:
The invention uses composite multilayer structures combining inorganic materials (silicon dioxide, aluminum oxide) with organic materials (polymer layers). This composite approach leverages the low theoretical permeability of inorganic materials while using organic materials to seal defects, achieving WVTR < 10^-4 g/cm2/day.
2Reliability
If multiple dense inorganic layers are alternated with soft organic layers to achieve low WVTR, then barrier performance improves, but device flexibility and substrate choice are constrained
Solution Approach 1:
The organic polymer layers in the multilayer structure act as flexible components that maintain device flexibility while providing defect-filling functionality. These thin film organic layers conform to flexible plastic substrates and maintain barrier performance on bent or flexible devices.
3Duration of action of stationary object
If pinholes and defects are present in inorganic layers, then water and oxygen permeation increases reducing device lifetime, but eliminating these defects requires high-cost rigid substrates for protection
Solution Approach 1:
Instead of trying to eliminate pinholes and defects from inorganic layers (which would require expensive rigid substrates), the invention converts these defects into opportunities by using organic layers to fill and seal them. The defects that would normally harm barrier performance are instead used to drive the adoption of a multilayer approach that achieves better performance at lower cost.
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 achieves significant reduction in water vapor transmission rates, improves substrate smoothness, and extends device lifetime by creating a robust, flexible, and cost-effective barrier that surpasses traditional substrate protection methods.
Implementation Method 1
A polymer may be deposited on various substrates, such as glass, plastics, metals, and polymers, using chemical vapor deposition (CVD) techniques
Implementation Method 2
which include plasma enhanced chemical vapor deposition (PECVD)
Implementation Method 3
introducing energy into said first mixture at a first power, thereby depositing a first layer on the substrate
Data Source
AI summary
Disclosed is an organic coating with a high degree of global planarization. Further disclosed is an iPECVD-based method of coating a substrate with an organic layer having a high degree of global planarization. Disclosed is a flexible, alternating organic and inorganic multi-layer coating with low water permeability, a high-degree of transparency, and a high-degree of global planarization. Also disclosed is an iPECVD-based method of coating a substrate with the alternating organic and inorganic multi-layer coating.