LED Reflective Layer Alloy Structure for Efficiency and Resistance
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Solution Overview
Problem
LEDs face challenges in achieving improved light efficiency and reduced resistance, particularly in semiconductor materials and layer structures.
Innovation Solution
The use of a reflective layer comprising alloys such as Ag-based, Al-based, or Sn, combined with an anti-oxidation layer like Au or TCO, and a light emitting semiconductor layer with a conductive structure, including an Ag-Pd-Cu alloy to enhance reflectivity and prevent grain boundary diffusion, while minimizing oxidation and interdiffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a reflective layer is used to improve light efficiency, then light efficiency is improved, but resistance increases
Solution Approach 1:
The reflective layer is constructed as a composite structure with multiple layers including Ag-Pd-Cu alloy layers and TCO layers. This composite structure achieves both high light reflectivity (improving light efficiency) and low electrical resistance by combining materials with complementary properties - the Ag-Pd-Cu alloy provides reflectivity while the TCO layer provides electrical conductivity.
2Illumination intensity
If pure Ag or Al is used for high reflectivity, then reflectivity is improved, but oxidation occurs increasing resistance
Solution Approach 1:
The TCO layer serves as an intermediary between the Ag-Pd-Cu alloy reflective layer and the semiconductor layer. This intermediary layer prevents oxidation of the Ag-Pd-Cu alloy layer (maintaining reflectivity) while providing a low-resistance electrical contact path to the semiconductor layer.
Solution Approach 2:
The TCO layer acts as a sacrificial protective layer that prevents oxidation of the underlying Ag-Pd-Cu alloy. By using this disposable protective layer, the expensive and sensitive Ag-Pd-Cu alloy is protected from degradation, maintaining its reflective properties over time.
3Reliability
If alloy materials are used to reduce resistance, then resistance is reduced, but light efficiency decreases
Solution Approach 1:
The reflective layer structure is designed with different local properties in different layers. The Ag-Pd-Cu alloy layers are optimized for electrical conductivity and reflectivity, while the TCO layers are optimized for electrical conductivity and oxidation resistance. Each layer performs its specific function locally, achieving both low resistance and high light efficiency at the device level.
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 results in increased light efficiency and reduced resistance, with reflectivity improved by up to 15% at specific wavelengths, and operating voltages suitable for efficient LED operation.
Implementation Method 1
a reflective layer comprising an alloy of at least one of an Ag-based alloy, an Al-based alloy, Ag, Al, Rh, or Sn, and at least one of Pd, Cu, C, Sn, In or Cr
Implementation Method 2
an anti-oxidation layer comprising at least one of Au, Pt, Rh, TCO or TCN
Data Source
AI summary
Disclosed is a light emitting device. The light emitting device comprises a reflective layer comprising an alloy of at least one of an Ag-based alloy, an Al-based alloy, Ag, Al, Rh, or Sn, and at least one of Pd, Cu, C, Sn, In or Cr, and a light emitting semiconductor layer comprising a second conductive semiconductor layer, an active layer and a first conductive semiconductor layer on the reflective layer.