Flexible Multilayer Scattering Substrate for OLED Light Extraction
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Solution Overview
Problem
Current flexible substrates for OLEDs face challenges with surface roughness, internal stress, and processing conditions, which affect the efficiency of light outcoupling and the flexibility of the substrate, particularly in achieving fine top surface roughness and compatibility with lateral OLED fabrication.
Innovation Solution
A flexible multilayer substrate comprising a thin flexible support layer, a light scattering layer with particles dispersed in a polymer matrix, and a planarization layer, where the scattering layer is positioned near the stress neutral plane to enhance flexibility and outcoupling, with specific materials and processing conditions to minimize internal stress and optimize surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a light scattering layer is added to improve light outcoupling efficiency, then light transmission is improved, but surface roughness increases and manufacturing complexity increases
Solution Approach 1:
The substrate is divided into multiple functional layers: a flexible support layer, a light scattering layer with particles dispersed in polymer matrix, and a planarization layer. This segmentation allows each layer to perform its specific function - the scattering layer enhances light outcoupling while the planarization layer restores surface smoothness for OLED fabrication compatibility.
Solution Approach 2:
The planarization layer acts as an intermediary between the light scattering layer and the OLED structure. It provides a smooth surface for subsequent OLED fabrication while allowing the underlying scattering layer to maintain its light outcoupling function, thus mediating between optical performance and manufacturing requirements.
2Ease of operation
If the substrate is made thinner to improve flexibility, then flexibility is improved, but mechanical strength decreases
Solution Approach 1:
The substrate uses composite materials including a flexible polymer support layer (such as polyimide or PEN) combined with a light scattering layer containing particles dispersed in a polymer matrix. This composite structure provides both the required flexibility for bendable displays and sufficient mechanical strength to prevent breakage during handling and operation.
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 improves the flexibility and outcoupling efficiency of OLEDs by reducing internal stress and achieving the required surface roughness, increasing light transmission and current efficiency while maintaining substrate flexibility.
Implementation Method 1
a light scattering layer disposed over the support layer, wherein the light scattering layer comprises light scattering particles dispersed in a polymer matrix
Data Source
AI summary
A flexible multilayer scattering substrate is disclosed. Built on a flexible supporting layer, the multilayer contains one or more scattering layers and other functional layers so that it can extract the trapped light in substrate and waveguide of an OLED. The processing of each layer is fully compatible with large area, flexible OLED manufactory, and by controlling processing conditions of each incorporated layer, the substrate microstructure can be tuned. Topographic features can be created on the top surface of substrate by changing the thickness and properties of the multilayer.