LED Redirection Layer for High Light Extraction and Luminance Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional light-emitting diodes (LEDs) face challenges in achieving high photon extraction efficiency and reducing the number of photon bounces, which can lead to increased costs and complexity or low extraction efficiency.
Innovation Solution
The development of a semiconductor light-emitting device with a redirection layer on the back surface, featuring nano-antennae, photonic bandgap structures, or meta-atoms, that exhibits non-specular internal reflective redirection of output light, along with position-dependent redirection, reflection, or transmission on one or both surfaces to achieve position-dependent luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional LED structures are used, then manufacturing is simpler, but photon extraction efficiency is low and number of photon bounces is high
Solution Approach 1:
The patent applies local quality by implementing position-dependent redirection and reflection properties at different locations within the LED device. The redirection layer and surface structures are designed to have spatially varying optical properties that locally control light propagation, enabling high photon extraction efficiency (80% or more) while maintaining manufacturing feasibility through targeted structural modifications rather than complete redesign
Solution Approach 2:
The patent segments the optical control function into multiple components: a redirection layer with position-dependent redirection, front and back surfaces with position-dependent reflection or transmission, and internal structures. This segmentation allows each component to be optimized independently for its specific function while working together to achieve high overall photon extraction efficiency with reduced manufacturing complexity
2Productivity
If redirection layers with nano-antennae or photonic structures are added, then photon extraction efficiency improves, but device complexity increases
Solution Approach 1:
The redirection layer in the patent serves multiple functions simultaneously: it provides non-specular internal reflective redirection, position-dependent redirection, and works in conjunction with surface structures to achieve both high photon extraction efficiency and reduced device complexity. This multi-functionality eliminates the need for separate components for each optical control function
Solution Approach 2:
The patent merges the redirection function with the back-surface structure by integrating the redirection layer directly onto the back surface of the semiconductor diode. This consolidation combines what could be separate components into a single integrated structure, achieving high photon extraction efficiency while minimizing the increase in device complexity
3Adaptability or versatility
If position-dependent redirection and reflection structures are implemented, then position-dependent luminance is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The patent implements position-dependent luminance control through local quality by designing redirection and reflection structures with spatially varying properties. The redirection layer and surface structures are configured to have position-dependent optical characteristics that locally control light extraction, enabling versatile luminance patterns while using manufacturing techniques suitable for achieving the required precision
4Productivity
If multiple photon bounces are allowed, then light extraction opportunity increases, but energy loss from absorption increases
Solution Approach 1:
The patent applies the skipping principle by enabling photons to rapidly exit the semiconductor diode through the front surface after minimal internal reflections. The redirection layer and position-dependent surface structures are designed to guide photons toward efficient extraction paths, reducing the number of bounces and minimizing energy loss from absorption while still achieving high overall extraction efficiency
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 enhances photon extraction efficiency to 80% or more and reduces the number of photon bounces to 30 or fewer, while achieving position-dependent luminance across the front surface, thereby improving light output and reducing manufacturing complexity.
Implementation Method 1
At least a portion of the back-surface redirection layer is structurally arranged, relative to the nominal output vacuum wavelength λ0, so as to exhibit non-specular internal reflective redirection of output light incident on the back surface within the diode structure
Implementation Method 2
one or both of the front or back surfaces including one or more structural arrangements that exhibit position-dependent redirection, reflection, or transmission of the output light
Implementation Method 3
The back-surface redirection layer includes one or more of (i) an array of nano-antennae, (ii) a partial photonic bandgap structure, (iii) a photonic crystal, or (iv) an array of meta-atoms or meta-molecules
Data Source
AI summary
A semiconductor diode structure has one or more light-emitting active layers and a redirection layer on the back surface that includes one or more of an array of nano-antennae, a partial photonic bandgap structure, a photonic crystal, or an array of meta-atoms or meta-molecules, and exhibits non-specular internal reflective redirection of output light incident thereon within the diode structure. One or both of the front or back surfaces exhibit position-dependent redirection, reflection, or transmission of the output light, including one or both of (i) position-dependent internal reflective redirection of output light incident on the back-surface or (ii) position-dependent internal reflective redirection, or position-dependent transmissive redirection, of output light incident on a front-surface layer or coating. Position dependence of luminance of output light exiting the diode structure can differ from position dependence of emission from the active layer. With uniform emission across the active layer, output light can exhibit position-dependent luminance.