Hole-Diffusion Layer for LED Efficiency
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Solution Overview
Problem
Semiconductor light emitting devices face inefficiencies in high current applications due to non-uniform hole current and reduced light emission efficiency, particularly in high current/high output fields where existing technologies fail to improve injection efficiency effectively.
Innovation Solution
Incorporating a hole-diffusion layer with three layers of different energy band gaps and resistance levels, including Al, between the electron-blocking layer and the p-type semiconductor layer, to disperse non-uniform hole current and enhance hole injection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional LED structure is used in high current applications, then device simplicity is maintained, but hole injection efficiency deteriorates and light emission efficiency decreases
Solution Approach 1:
The hole-diffusion layer is divided into three distinct sub-layers (first, second, and third sub-layers) with progressively increasing Al composition ratios. This segmentation allows each sub-layer to address specific aspects of hole transport and barrier mitigation, improving overall hole injection efficiency while managing the complexity through a systematic gradient structure
Solution Approach 2:
Each sub-layer of the hole-diffusion layer has a locally optimized Al composition ratio, with the first sub-layer having a lower ratio and the third sub-layer having a higher ratio. This local quality variation creates a gradient that progressively addresses the hole barrier in different regions of the valence band, enhancing hole injection efficiency at critical interfaces
2Power
If high current is applied to achieve high output, then light output increases, but non-uniform hole current increases and light emission efficiency decreases
Solution Approach 1:
The Al composition ratio is changed as a key parameter across the three sub-layers of the hole-diffusion layer. By progressively increasing the Al composition ratio from the first to the third sub-layer, the structure modifies the valence band profile to reduce hole barriers, enabling efficient hole injection and uniform hole current distribution even at high current densities, thus maintaining high light emission efficiency alongside high light output
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 improves light emission efficiency and output characteristics by mitigating the hole barrier in the valence band, leading to better performance in high current regions and increased internal quantum efficiency.
Implementation Method 1
a hole-diffusion layer disposed between the electron-blocking layer and the p-type semiconductor layer
Data Source
AI summary
A lighting system includes a lighting unit comprising at least one lighting device, a sensing unit configured to measure at least one of atmospheric temperature and humidity, a controlling unit configured to compare the at least one of the temperature and the humidity measured by the sensor unit with set values and determine a color temperature of the lighting unit as a result of the comparison, and a driving unit configured to drive to the lighting unit to have the determined color temperature.