Micro-LED Light Extraction with Current Narrowing and Surface Lenses
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Solution Overview
Problem
Micro-sized displays face challenges in improving light extraction efficiency due to limitations in light collection and power efficiency, particularly with small pixel pitches and high non-radiation recombination at end surfaces, which affect the overall brightness and efficiency of light emitting devices.
Innovation Solution
A light emitting device is designed with a first compound semiconductor layer, an active layer, and a second compound semiconductor layer, where a current narrowing structure is provided in the first layer and a light collecting structure, such as a lens, is on the light exit surface of the second layer, limiting the light emitting region and increasing the proportion of light entering the acceptance angle of the lens, thereby enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a micro-sized display is used, then device size is reduced, but light extraction efficiency deteriorates
Solution Approach 1:
The light emitting device is segmented into distinct functional layers: a first compound semiconductor layer for current control, an active layer for light generation, and a second compound semiconductor layer with light collecting structures. This segmentation allows each layer to be optimized for its specific function, enabling efficient light extraction in a compact device.
Solution Approach 2:
Light collecting structures are added to the fourth surface (light exit surface) of the second compound semiconductor layer, introducing a new dimensional element for light management. This dimensional addition enables effective light collection and extraction without increasing the overall device footprint, resolving the contradiction between small size and light extraction efficiency.
2Loss of energy
If a current narrowing structure is provided, then light emitting region is limited and power efficiency improves, but device complexity increases
Solution Approach 1:
The current narrowing structure is merged with the first compound semiconductor layer, combining current control functionality with the existing layer structure. This integration approach achieves power efficiency improvement without proportionally increasing device complexity, as the current narrowing function is incorporated into an already-necessary structural element.
3Loss of energy
If light collecting structures are added to the light exit surface, then light extraction efficiency improves, but device complexity increases
Solution Approach 1:
The second compound semiconductor layer serves multiple functions: it provides structural support, facilitates light generation through the active layer, and incorporates light collecting structures on its fourth surface for efficient light extraction. This multi-functionality allows the same layer to contribute to multiple performance aspects without requiring separate dedicated components, thereby improving light extraction efficiency without proportionally increasing device complexity.
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
This configuration increases light extraction efficiency and power efficiency by focusing light emission within the acceptance angle of the lens, reducing boundary reflection losses, and minimizing device size while maintaining high refractive index capture capabilities.
Implementation Method 1
a light collecting structure, such as a lens, is on the light exit surface of the second layer, limiting the light emitting region and increasing the proportion of light entering the acceptance angle of the lens
Implementation Method 2
a current narrowing structure is provided in the first layer, limiting the light emitting region of the active layer
Data Source
AI summary
A light emitting device according to one embodiment of the present disclosure includes a first compound semiconductor layer having a first surface and a second surface that are opposed to each other, an active layer facing the second surface of the first compound semiconductor layer, a second compound semiconductor layer having a third surface that faces the active layer and a fourth surface that is opposed to the third surface and serves as a light exit surface and including one or a plurality of light collecting structures on the fourth surface, and a current narrowing structure provided within the first compound semiconductor layer or the second compound semiconductor layer.