LED Active Layer with Dummy Layers for High CRI and Low Voltage
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Solution Overview
Problem
Conventional light emitting devices face challenges in enhancing color rendering index (CRI) and optical power while maintaining low driving voltage, particularly at peak wavelengths of 450 nm or more, where phosphor characteristics deteriorate and optical power decreases.
Innovation Solution
The light emitting device incorporates a specific structure with (T+1) barrier layers, T well layers, and dummy layers between well and barrier layers, where T>N, to adjust the energy bandgap and minimize bulk resistance, thereby improving optical power and CRI while reducing driving voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional light emitting devices are used, then manufacturing is simpler, but optical power and color rendering index deteriorate at peak wavelengths of 450 nm or more
Solution Approach 1:
The active layer is segmented into multiple quantum wells (first, second, and third quantum wells) with different well widths, surrounded by multiple barrier layers. This segmentation allows each quantum well to contribute differently to the emission spectrum, enhancing optical power and CRI at wavelengths of 450 nm or more while managing the complexity through a systematic multi-layer structure.
Solution Approach 2:
Different regions of the active layer are given different local qualities by varying the well widths of the quantum wells. The first quantum well has a different well width than the second and third quantum wells, creating localized variations in emission characteristics. This allows optimization of optical power and CRI at specific wavelengths without requiring complete redesign of the entire structure.
2Illumination intensity
If phosphor is used to enhance color rendering, then CRI improves, but optical power decreases due to phosphor characteristic deterioration
Solution Approach 1:
The patent replaces the phosphor-based color conversion mechanism with a direct multi-quantum-well light emission mechanism. Instead of using phosphor to convert blue light to other wavelengths (which causes optical power loss), the active layer directly emits multiple wavelengths through quantum wells with different well widths, achieving both high CRI and high optical power without phosphor-related energy losses.
Solution Approach 2:
The emission characteristics are optimized by changing the well width parameter of the quantum wells. By adjusting the well widths of the first, second, and third quantum wells differently, the emission spectrum is tuned to achieve high CRI and optical power at wavelengths of 450 nm or more, replacing the need for phosphor-based wavelength conversion.
3Use of energy by moving object
If driving voltage is reduced, then energy consumption decreases, but optical power and CRI performance deteriorate
Solution Approach 1:
The patent introduces dummy layers between the quantum wells and blocking layers that can dynamically adjust the electric field distribution and carrier injection characteristics. These dummy layers with different hole injection barriers create a more efficient carrier transport pathway, enabling high optical power and CRI performance at reduced driving voltages by optimizing the dynamic behavior of charge carriers in the active layer.
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 enhances optical power and CRI at peak wavelengths of 450 nm or more, maintains the quality of the active layer, and lowers the required driving voltage by minimizing bulk resistance and band bending.
Implementation Method 1
A light emitting diode (LED) is a semiconductor light emitting diode to convert current into light
Implementation Method 2
The active layer includes (T+1) barrier layers, T well layers between the (T+1) barrier layers, and a dummy layer between N well layers adjacent to the second conductive semiconductor layer and N barrier layers adjacent to the N well layers
Data Source
AI summary
Disclosed are a light emitting device and a light emitting device package. The light emitting device includes a first conductive semiconductor layer, an active layer on the first conductive semiconductor layer, and a second conductive semiconductor layer on the active layer. The active layer includes (T+1) barrier layers, T well layers between the (T+1) barrier layers, and a first dummy layer between N well layers adjacent to the second conductive semiconductor layer and N barrier layers adjacent to the N well layers, in which T>N≧1.