Light-Emitting Element With Low-Index Insulative Layer
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Solution Overview
Problem
Conventional light-emitting elements face inefficiencies in luminous efficiency due to total internal reflection, particularly at interfaces with higher refractive index materials, which limits their power output and light extraction capabilities.
Innovation Solution
A light-emitting element design incorporating a non-oxide insulative layer with a refractive index less than 1.4, positioned between a transparent conducting structure and a window layer, along with a reflection structure and an omni-directional reflector, reduces total internal reflection and enhances light extraction efficiency by increasing the critical angle at the interface and improving current diffusion and ohmic contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional light-emitting element uses high refractive index materials at interfaces, then light emission is enhanced, but total internal reflection increases and light extraction efficiency decreases
Solution Approach 1:
The patent introduces a non-oxide insulative layer with low refractive index (less than 1.4) as an intermediary between the light-emitting stack and the window layer. This intermediate layer acts as a refractive index bridge, reducing the abrupt refractive index difference at the interface and thereby minimizing total internal reflection while maintaining light emission enhancement.
Solution Approach 2:
The patent changes the refractive index parameter of the insulative layer to be less than 1.4, which is lower than conventional oxide insulative layers. This parameter change optimizes the critical angle at the interface, reducing total internal reflection and improving light extraction efficiency without sacrificing light emission intensity.
2Loss of energy
If the surface area of the non-oxide insulative layer is increased, then light extraction efficiency is improved, but device area increases
Solution Approach 1:
The patent applies the non-oxide insulative layer selectively in specific regions rather than uniformly across the entire device. By optimizing the surface area ratio of the non-oxide insulative layer to be between 10% to 50% of the total surface area, the patent achieves improved light extraction efficiency at critical interfaces while minimizing the overall device area increase.
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 significantly increases the power output of the light-emitting element, with surface area ratios and power performance improvements, achieving greater than 50 mW power when the surface area of the non-oxide insulative layer is between 10% to 50% of the total surface area, and enhances mechanical strength and adhesion.
Implementation Method 1
Conventional light-emitting elements face inefficiencies in luminous efficiency due to total internal reflection, particularly at interfaces with higher refractive index materials
Implementation Method 2
a refractive index of the non-oxide insulative layer is less than 1.4... increases the critical angle at the interface
Implementation Method 3
along with a reflection structure and an omni-directional reflector, reduces total internal reflection and enhances light extraction efficiency
Data Source
AI summary
A light-emitting element includes a light-emitting stack which has an active layer, and a non-oxide insulative layer below the light-emitting stack, wherein a refractive index of the non-oxide insulative layer is less than 1.4.