Flexible Light Emitting Transducer with Micro-Structured Substrate
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Solution Overview
Problem
Existing flexible light-emitting devices, such as OLEDs and LEDs, face challenges in bending without introducing severe defects, including cracks in thin film encapsulation layers and transparent electrodes, limiting their application to curved surfaces due to internal stresses and brittle material fragility.
Innovation Solution
A flexible light-emitting transducer with a stretchable and compressible substrate featuring a micro-scale surface pattern of raised and depressed portions, allowing for controlled bending and reduced stress, enabling attachment to various surfaces without cracking, including curved and 3D structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If flexible light-emitting devices are bent to achieve curved surface application, then adaptability to surfaces is improved, but cracks in thin film encapsulation layers and transparent electrodes are introduced
Solution Approach 1:
The substrate is divided into multiple segments with different mechanical properties. The first substrate layer provides flexibility and stretchability, while the second substrate layer provides structural support and protection. This segmentation allows the device to bend and stretch without causing cracks in the encapsulation layers or transparent electrodes, resolving the contradiction between adaptability and structural integrity.
Solution Approach 2:
The device uses a composite substrate structure consisting of at least two different substrate layers with complementary properties. The first substrate layer (e.g., polymer film) provides elasticity and stretchability, while the second substrate layer (e.g., rigid or semi-rigid material) provides mechanical strength and stability. This composite approach enables the device to adapt to curved surfaces while maintaining reliability and preventing cracks.
2Reliability
If transparent electrodes made of brittle material such as ITO are used, then electrical conductivity is improved, but cracks are introduced during bending
Solution Approach 1:
The transparent electrode structure is designed with local quality variations. The electrode is positioned within the multi-layer substrate structure where it is protected from excessive stress during bending. The local environment provided by the flexible substrate layers allows the brittle ITO material to maintain its electrical conductivity without cracking, even when the overall device is bent or stretched.
Solution Approach 2:
The multi-layer substrate structure provides beforehand cushioning for the transparent electrode. The flexible substrate layers absorb and distribute mechanical stresses before they reach the brittle ITO electrode, preventing crack formation during bending operations. This protective structure is built in advance to safeguard the electrical conductivity of the electrode.
3Adaptability or versatility
If bending radius is reduced below centimeter order to achieve tighter curvature, then adaptability to complex surfaces is improved, but severe lifetime reducing defects are introduced
Solution Approach 1:
The substrate structure is designed to be dynamic and adaptable. The first substrate layer can stretch and deform elastically to accommodate small bending radii without causing permanent damage. This dynamic response allows the device to adapt to tightly curved surfaces while maintaining its structural integrity and extending its operational lifetime, overcoming the limitation of fixed bending radius requirements.
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 transducer can be stretched or compressed by 20-25% without introducing lifetime-destructive defects, maintaining flexibility and robustness, allowing attachment to surfaces with varying shapes and environmental changes, thus extending its usability and lifespan.
Implementation Method 1
a substrate which is stretchable and compressible
Data Source
AI summary
A light emitting transducer including a flexible sheet having a bottom side and a top side, the flexible sheet including a substrate that is stretchable and compressible, the substrate having a bottom substrate surface at the bottom side, and a top substrate surface facing towards the top side, the top substrate surface comprising a surface pattern of a plurality of raised and depressed micro-scale surface portions which extend in at least one direction; a light emitting diode layer above the substrate and conforming in shape to the top substrate surface, the light emitting diode layer corresponding with the surface pattern of the top substrate surface, wherein the light emitting diode layer has a bottom diode surface facing towards the bottom side, and a top diode surface facing towards the top side, a bottom electrode on the bottom diode surface, and a top electrode on the top diode surface.