Micro-LED Light Extraction Patterning for Uniform Output Stability
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Solution Overview
Problem
Existing light emitting display devices face challenges in achieving uniform light output characteristics and electrical stability, particularly in ultrasmall light emitting elements like micro-LEDs and nano-LEDs, due to issues with light extraction efficiency and structural design.
Innovation Solution
The implementation of light extraction patterns with groove and protrusion features on the light output surface of light emitting elements, combined with a protective layer covering the semiconductor stack, ensures uniform light distribution and enhances electrical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If light extraction patterns are added to improve light output characteristics, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
The light extraction pattern is segmented into multiple groove portions arranged in specific patterns (e.g., linear, radial, or grid arrangements) on the light output surface. Each groove portion acts as an independent light extraction unit, allowing optimized light extraction across different regions of the semiconductor stack while maintaining manufacturability through standardized repeating units.
Solution Approach 2:
The invention transitions from a flat light output surface to a three-dimensional structured surface by adding groove portions that extend into the semiconductor material. This dimensional change creates multiple light extraction pathways and interfaces, significantly improving light extraction efficiency by utilizing total internal reflection and scattering effects at the groove interfaces.
2Manufacturing precision
If groove portions are spaced from the end of the light output surface, then manufacturing precision is improved, but light extraction efficiency deteriorates
Solution Approach 1:
The groove portions are strategically positioned with different spacing and orientations in different regions of the light output surface. For example, grooves may be arranged with specific pitch near the edges to facilitate manufacturing alignment, while maintaining optimal spacing in central regions for maximum light extraction. The groove depth, width, and orientation are also locally optimized based on the specific light extraction requirements of each region.
3Reliability
If protective layer covers side surfaces of semiconductor stack, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The protective layer is designed to extend over the side surfaces of the semiconductor stack before final packaging, creating a preliminary protection barrier against moisture and contaminants. This preliminary action prevents degradation of the semiconductor materials and maintains electrical stability throughout the device lifecycle, while the extension geometry is optimized to be compatible with standard packaging processes.
Data Source
AI summary
A display device includes: a substrate; pixel electrodes on the substrate; and light emitting elements on the pixel electrodes, where each of the light emitting elements includes: a semiconductor stack including a first semiconductor layer, an active layer on the first semiconductor layer, and a second semiconductor layer on the active layer; light extraction patterns on a light output surface of the semiconductor stack and including groove portions that are spaced from an end of the light output surface and protrusion portions around the groove portions; and a protective layer covering side surfaces of the semiconductor stack, and where the light emitting elements include the light extraction patterns having a same shape.