Flexible OLED Encapsulation with Wavy Outer Inorganic Layer
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Solution Overview
Problem
Flexible OLED devices face encapsulation failure due to cracking of the outermost inorganic film layer under bending stress, as it bears maximum bending stress and is prone to breakage, compromising the entire encapsulation structure.
Innovation Solution
A novel encapsulation layer configuration with a first and second inorganic layer and an organic layer, where the second inorganic layer has a continuous wavy curved configuration, formed by thermal stress differences, increasing contact area and reducing stress on the outer inorganic layer, and an optically clear adhesive is used to level the configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a three-layer inorganic/organic/inorganic encapsulation structure is used, then moisture and oxygen blocking performance is improved, but the outermost inorganic layer is subjected to maximum bending stress and prone to cracking
Solution Approach 1:
The outer inorganic layer is designed with a wavy curved configuration instead of a flat structure. This curvature allows the layer to better accommodate bending stresses by distributing stress across the undulating surface, preventing stress concentration and cracking while maintaining the protective encapsulation function.
Solution Approach 2:
The invention changes the geometric parameters of the outer inorganic layer by introducing a wavy profile with specific amplitude and wavelength. This parameter modification transforms the stress distribution characteristics, enabling the layer to withstand bending forces that would cause cracking in a flat configuration while preserving moisture and oxygen barrier properties.
2Strength
If the outer inorganic layer is made thinner to reduce stress, then bending resistance is improved, but moisture and oxygen blocking performance deteriorates
Solution Approach 1:
By introducing a wavy curved profile to the outer inorganic layer, the invention achieves enhanced bending resistance without reducing layer thickness. The curved geometry provides mechanical flexibility and stress distribution, allowing thin layers to maintain both structural integrity under bending and effective barrier properties against moisture and oxygen penetration.
3Ease of manufacture
If a flat encapsulation structure is used, then fabrication simplicity is maintained, but stress concentration occurs at bending places leading to cracking
Solution Approach 1:
The wavy curved configuration of the outer inorganic layer can be integrated into existing fabrication processes through controlled deposition techniques. The curved profile is formed during the layer deposition process itself, maintaining fabrication simplicity while fundamentally improving bending resistance through the stress-distributing geometric structure.
Solution Approach 2:
The fabrication process itself generates the desired wavy curved configuration through controlled deposition conditions. The process parameters are adjusted to naturally form the curved profile during layer formation, eliminating the need for additional post-processing steps to create the stress-distributing geometry.
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 curved configuration of the outer inorganic layer reduces the risk of breakage and enhances the contact area with the inner organic layer, effectively mitigating encapsulation failure under bending stress without additional processing steps, simplifying the fabrication process.
Implementation Method 1
a thermal stress difference exists between a film thermal stress S1 of the first organic layer and a film thermal stress S2 of the second inorganic layer, and the second inorganic layer is spontaneously formed with the curved configuration during fabrication thereof due to the existence of the thermal stress difference
Data Source
AI summary
The present disclosure provides a flexible organic light-emitting diode (OLED) device and a fabrication method thereof, wherein the flexible organic light emitting diode (OLED) device includes a substrate, an array unit layer, a light-emitting device layer, and an encapsulation layer that are sequentially disposed. The encapsulation layer includes a first inorganic layer, a first organic layer and a second inorganic layer that are sequentially disposed. The second inorganic layer has a continuous wavy curved-configuration, and an interface between the second inorganic layer and the first organic layer has a continuous wavy curved-shape. The present disclosure is directed to a flexible OLED device using a novel outer inorganic layer to increase the contact area between the outer inorganic layer and the inner organic layer, thereby effectively reducing risks of breakage of the outer inorganic layer.