Pinhole-Free Dielectric Sealing for Display Devices
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Solution Overview
Problem
Display devices, particularly OLED and polyLEDs, are vulnerable to oxygen and moisture exposure leading to degradation, and existing sealing methods are either ineffective or require high temperatures incompatible with polymer-based devices, while also being sensitive to mechanical forces that can break the surface and compromise the seal.
Innovation Solution
A dielectric sealing structure with at least two layers, optionally a third transparent layer, combined with a stabilisation layer deposited using low-temperature methods like PECVD or inkjet printing, forms a pinhole-free, scratch-resistant, and water/oxygen impermeable barrier that encapsulates protrusions and provides mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal films are evaporated to seal display devices, then sealing against oxygen and moisture is achieved, but the films contain pinholes requiring greater thickness which results in poor light transmission
Solution Approach 1:
The patent employs a composite sealing structure consisting of a dielectric sealing layer (such as silicon oxide, silicon nitride, or silicon oxynitride) combined with an organic planarisation layer. This composite approach creates a pinhole-free barrier that provides effective sealing against oxygen and moisture while maintaining sufficient light transmission, overcoming the limitations of single-layer metal film evaporation methods.
2Reliability
If temperatures above 300°C are used during the sealing process, then proof encapsulation is achieved, but polymer-based devices are damaged due to incompatibility with high temperatures
Solution Approach 1:
The patent utilizes plasma-enhanced chemical vapour deposition (PECVD) to deposit dielectric sealing layers at low temperatures (below 300°C, typically in the range of 100-250°C). This parameter change in the deposition process temperature enables effective encapsulation and sealing of polymer-based display devices without causing thermal damage to the organic or polymer materials, while still achieving pinhole-free barriers with excellent moisture and oxygen protection.
3Strength
If additional protective layers and scratch resistant layers are deposited on the barrier assembly, then mechanical strength is improved, but the manufacturing process becomes complicated and expensive and the assembly becomes relatively thick
Solution Approach 1:
The patent designs the organic planarisation layer to serve multiple functions simultaneously: it provides mechanical protection and scratch resistance to the underlying dielectric sealing layer, ensures uniform thickness distribution, and maintains optical quality. By making this layer multi-functional, the patent eliminates the need for separate protective and scratch-resistant layers, thereby simplifying the manufacturing process, reducing production complexity and cost, and avoiding excessive thickness while still achieving improved mechanical strength.
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 solution significantly extends the durability of display devices by preventing moisture and oxygen ingress, enhancing mechanical robustness, and eliminating the need for additional protective layers, resulting in thinner, lighter, and more durable displays with improved optical properties.
Implementation Method 1
Efforts have been made by evaporating metal films to seal display devices
Implementation Method 2
The stabilisation layer is formed on the sealing structure and is intended to stabilise and protect the sealing structure
Implementation Method 3
The stabilisation layer is formed on the sealing structure and is intended to stabilise and protect the sealing structure, as well as to provide a scratch resistant surface on the display device
Implementation Method 4
The sealing structure comprises at least two layers of dielectric material. By using at least two layers, a pinhole free structure is obtained
Data Source
AI summary
An encapsulation structure for a display device includes a sealing structure and a stabilization layer. The sealing structure is an essentially water/oxygen impermeable film which covers environmentally sensitive parts and protrusions on the display device. The stabilization layer covers the display device, protrusions on the display and the sealing structure with a scratch resistant protective layer, resulting in a water/oxygen impermeable and scratch resistant encapsulation structure.