Multilayered White LED Using Quantum Dots
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Solution Overview
Problem
Conventional white LEDs using UV light as an excitation source suffer from low luminescence efficiency and instability due to direct excitation of quantum dots, leading to decreased performance over time, and existing solutions with red phosphors have low phosphor conversion efficiency and color rendering issues.
Innovation Solution
A multilayered white LED structure comprising a UV LED, a phosphor mixture layer of green and blue phosphors, and a red quantum dot layer, where the quantum dots are excited by visible light emitted from the phosphors rather than directly by UV light, enhancing luminescence efficiency and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If quantum dots are directly excited by UV light, then luminescence is generated, but luminescence efficiency decreases and stability deteriorates over time
Solution Approach 1:
The patent introduces phosphors as intermediary materials between the UV light source and quantum dots. The phosphors absorb UV light and convert it to visible light, which then excites the quantum dots. This intermediary conversion process prevents direct UV excitation of quantum dots, thereby maintaining luminescence efficiency and stability over time while avoiding the degradation issues associated with direct UV exposure.
2Illumination intensity
If red phosphors are used to achieve white light emission, then white light is generated, but phosphor conversion efficiency is low and color rendering is poor
Solution Approach 1:
The patent employs a composite phosphor system combining multiple phosphor materials with different emission characteristics. By using a combination of phosphors rather than a single red phosphor, the system achieves improved overall conversion efficiency and superior color rendering properties, as each phosphor contributes different wavelengths that together produce high-quality white light.
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
The solution achieves high luminescence efficiency and stable white light emission by avoiding direct UV excitation of quantum dots, maintaining performance over time and improving color rendering, making it suitable for long-term applications.
Implementation Method 1
a UV LED for emitting UV light
Implementation Method 2
a phosphor mixture layer including a green phosphor and a blue phosphor, formed on the UV LED
Implementation Method 3
a red quantum dot layer formed on the phosphor mixture layer, in which quantum dots are excited by green and blue visible light
Data Source
AI summary
A multilayered white light emitting diode and a method of fabricating the same include forming a phosphor mixture layer including a green phosphor and a blue phosphor on a UV light emitting diode and forming a red quantum dot layer on the phosphor mixture layer. In the white light emitting diode of the present invention, the quantum dots are excited by green and blue visible light, thus increasing luminescence efficiency and realizing stable white light. Moreover, the white light emitting diode can be widely used as a light source having high output and high efficiency, thus being capable of substituting for a backlight unit of an illumination device or display device.