Optical Substrate with Arc-Shaped Projections for Broadband Light Extraction
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Solution Overview
Problem
Existing organic light emitting diodes and organic thin film solar cells face challenges in achieving high light extraction efficiency across the entire visible light region due to the limitations of constant period recessing and protruding structures, which are effective for specific wavelengths but not broad band wavelengths, and the difficulty in maintaining grating structures during the manufacturing process.
Innovation Solution
A substrate with a recessing and protruding structure featuring overlapping periodic components with different periods, where the first and second periodic structures have pitches that satisfy specific relationships, and protrusions with arc-shaped outlines, enhancing light extraction efficiency by allowing extraction of multiple wavelengths and maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a constant period recessing and protruding structure is used, then light extraction efficiency for specific wavelengths is improved, but light extraction efficiency across the entire visible spectrum deteriorates
Solution Approach 1:
The single periodic structure is segmented into multiple periodic structures with different periods. Each periodic component extracts light at different wavelengths, collectively covering the entire visible spectrum while maintaining manufacturing precision for each wavelength band
Solution Approach 2:
The recessing and protruding structure is designed to perform multiple functions simultaneously by incorporating periodic components with different periods, enabling the same structure to extract multiple wavelengths across the visible spectrum rather than being limited to a single wavelength range
2Manufacturing precision
If complex grating structures are formed on the substrate, then light extraction efficiency is improved, but structural integrity during manufacturing deteriorates
Solution Approach 1:
The complex grating structure is segmented into multiple simpler periodic structures that can be formed sequentially using different particle sizes as masks. This segmentation maintains structural integrity during manufacturing while achieving the light extraction efficiency of complex gratings
Solution Approach 2:
Particle monolayers are formed as preliminary masks before etching the grating structures. This preliminary action protects the substrate and enables precise formation of multiple periodic structures while maintaining structural integrity throughout the manufacturing process
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 proposed solution significantly improves light extraction efficiency for organic light emitting diodes and organic thin film solar cells by enabling the extraction of light across the entire visible spectrum and maintaining the structural integrity of the grating patterns, leading to enhanced luminance and photoelectric conversion efficiency.
Implementation Method 1
the two-dimensional grating structure provided on the surface of the cathode conductive layer serves as a diffraction grating. This enables extraction of energy, in the form of light, which is otherwise lost as surface plasmons
Implementation Method 2
some of the near-field light from the organic EL layer is converted into surface plasmons on the surface of the cathode conductive layer and lost
Data Source
AI summary
Provided is an optical element substrate with which it is possible to increase the efficiency of use of light energy. An uneven structure on one substrate surface for an optical element is provided with a plurality of projections. The contour shape of the projections has an arc shape in plan view facing the one surface. The contour shape is formed by a first arc section and second arc section having different center points. The first arc section and second arc section bulge in mutually opposite directions.