Hyperbolic Metamaterial LED for Small-Pixel Light Extraction
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Solution Overview
Problem
Miniature light-emitting diode (LED) display panels face challenges with low conversion efficiency and high energy consumption due to high non-radiative recombination rates and surface state density issues, limiting their use in wearable devices like head-mounted displays and near-eye displays.
Innovation Solution
Incorporating a hyperbolic metamaterial structure coupled to a quantum well layer at the p-n junction of the LED, which enhances radiative recombination and impedance-matches with the surrounding medium to increase light output, and is patterned for specific polarization and direction of emitted light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If LED size is reduced for miniature display applications, then device dimensions are improved, but conversion efficiency deteriorates due to increased non-radiative recombination
Solution Approach 1:
The patent changes the optical parameters of the LED by integrating a hyperbolic metamaterial structure that modifies the local density of optical states and enhances radiative recombination rates. This parameter change allows small LED pixels to maintain high conversion efficiency by altering the electromagnetic environment rather than changing the physical size
Solution Approach 2:
The patent uses composite materials by combining conventional semiconductor LED structures with hyperbolic metamaterials (composed of alternating metal and dielectric layers). This composite structure enables simultaneous achievement of miniaturization and high efficiency by leveraging the unique optical properties of metamaterials to suppress non-radiative recombination
2Volume of moving object
If LED size is reduced, then device dimensions are improved, but light output intensity deteriorates
Solution Approach 1:
The hyperbolic metamaterial structure changes the optical parameters by enhancing the radiative recombination rate and modifying light extraction efficiency. This allows small LED pixels to produce sufficient light output intensity by altering the electromagnetic field distribution and increasing the probability of radiative transitions
Solution Approach 2:
The hyperbolic metamaterial acts as an intermediary between the quantum well layer and the external environment, mediating the light extraction process. It enhances coupling between the quantum well and free space modes, thereby increasing light output intensity from miniaturized LED structures
3Volume of moving object
If LED size is reduced, then device dimensions are improved, but energy consumption increases
Solution Approach 1:
By changing the optical parameters through hyperbolic metamaterial integration, the patent improves radiative efficiency and reduces non-radiative losses. This parameter change decreases the electrical power required to produce a given light output, thereby reducing energy consumption in miniature LED displays
Solution Approach 2:
The composite structure of semiconductor and metamaterial layers creates enhanced light-matter interaction that improves conversion efficiency. This reduces the amount of electrical energy wasted as heat and increases the fraction converted to useful light, lowering overall energy consumption
4Volume of moving object
If LED size is reduced, then device dimensions are improved, but conversion efficiency deteriorates
Solution Approach 1:
The patent changes key optical parameters by introducing hyperbolic metamaterials that modify the local density of optical states and enhance radiative recombination rates. This parameter change directly improves conversion efficiency in small LED pixels by increasing the radiative-to-nonradiative recombination ratio
Solution Approach 2:
The hyperbolic metamaterial serves as an intermediary that enhances coupling between electron-hole recombination events and photons. This intermediary structure improves conversion efficiency by facilitating radiative transitions and reducing carrier loss to non-radiative pathways in miniaturized LEDs
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-emitting efficiency by shortening excited energy state lifetimes, leading to brighter, more energy-efficient displays with improved color saturation and reduced energy consumption.
Implementation Method 1
An efficiency of an LED is determined by a ratio of radiative and non-radiative recombination of electrons and electron holes at a p-n junction of the LED
Implementation Method 2
A hyperbolic metamaterial structure in the second semiconductor region is coupled to the quantum well layer
Implementation Method 3
The array of features may have a plasmonic resonance optical frequency within a spectral gain band of the quantum well layer
Implementation Method 4
The features of the array may be configured to provide a pre-defined polarization of emitted light
Data Source
AI summary
A light-emitting diode includes a first semiconductor region of one of p- or n-conductivity types, a second semiconductor region of the other one of p- or n-conductivity types, forming a p-n junction with the first semiconductor region, and a quantum well layer at the p-n junction between the first and second semiconductor regions. A hyperbolic metamaterial structure is provided in the second semiconductor region. The hyperbolic metamaterial structure is coupled to the quantum well layer for extracting light from the quantum well layer. The hyperbolic metamaterial structure may be patterned to provide an array of nanoantennas to apodize the emitted beam, and to control the polarization state of the emitted beam.