Nanorod Micro-LED Refractive Index Layer for Light Extraction
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Solution Overview
Problem
Current micro-light-emitting diodes (LEDs) face challenges in achieving high light extraction efficiency due to total internal reflection, which limits their performance in display devices.
Innovation Solution
The development of nanorod type micro-LEDs with a multi-quantum well layer and a functional material layer that increases the total internal reflection angle by reducing the refractive index gradient between the nanorod stack structure and air, enhancing light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional micro-LED structure is used, then the device structure is simple, but the light extraction efficiency is low due to total internal reflection
Solution Approach 1:
The patent introduces a functional material layer with intermediate refractive index (1.3-1.6) between the nanorod stack structure (refractive index 2.4-2.9) and air (refractive index 1.0). This intermediary layer acts as a refractive index bridge, reducing the abrupt refractive index difference at the interface and minimizing total internal reflection, thereby improving light extraction efficiency without complicating the device structure
Solution Approach 2:
The patent modifies the refractive index parameter by introducing a functional material layer with specifically controlled refractive index (1.3-1.6). This parameter change creates a gradual refractive index transition from the nanorod stack structure through the functional material layer to air, effectively reducing total internal reflection and improving light extraction efficiency
2Device complexity
If the refractive index difference between nanorod stack structure and air is large, then the device structure is simple, but the total internal reflection angle is small limiting light emission
Solution Approach 1:
The functional material layer serves as an optical intermediary with refractive index (1.3-1.6) between the nanorod stack structure (2.4-2.9) and air (1.0). This intermediary reduces the total internal reflection angle by creating a gradual refractive index transition, allowing more light to escape at larger angles and improving overall light emission efficiency without adding structural complexity
Solution Approach 2:
The patent addresses the angular limitation in the radial dimension by introducing a functional material layer that modifies light propagation in all directions around the nanorod stack structure. This dimensional approach increases the total internal reflection angle in the radial direction, enabling light emission at wider angles and improving illumination intensity
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 approach significantly increases light extraction efficiency, leading to improved brightness and clarity in display devices with reduced power consumption.
Implementation Method 1
increasing a total internal reflection angle of the nanorod stack structure
Implementation Method 2
The functional material layer has a refractive index between a refractive index of the nanorod stack structure and a refractive index of air
Data Source
AI summary
A nanorod type micro-light emitting diode (LED) includes a nanorod stack structure including a multi-quantum well layer and emitting light from a side surface, and a functional material layer covering the side surface of the nanorod stack structure and increasing a total internal reflection angle of the nanorod stack structure. The functional material layer has a refractive index between a refractive index of the nanorod stack structure and a refractive index of air, and includes a plurality of material layers having a refractive index distribution in which a refractive index decreases as a distance from the side surface increases.