Blue LED Quantum Dot Light Emission With Low Secondary Absorption
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Solution Overview
Problem
Conventional light emitting devices using quantum dots suffer from secondary absorption, leading to reduced luminous efficiency, particularly in applications requiring brighter light with lower power consumption.
Innovation Solution
Employing KSF and MGF phosphors as red phosphors instead of red quantum dots, which absorb blue light and emit red light with minimal absorption of green light, thereby reducing secondary absorption and enhancing luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If red quantum dots are used to emit red light, then color purity is improved, but secondary absorption occurs reducing luminous efficiency
Solution Approach 1:
The patent changes the material parameter from red quantum dots to red phosphors with specific emission characteristics. The red phosphors are selected to have emission peaks that do not overlap with the green light wavelength range, thereby eliminating secondary absorption while maintaining color purity through careful selection of phosphor emission parameters
Solution Approach 2:
The patent converts the harmful secondary absorption effect into a beneficial design criterion by selecting red phosphors whose emission characteristics naturally avoid absorbing green light. This transforms the problem of secondary absorption into a guiding principle for material selection, where the red phosphor's emission spectrum is specifically chosen to prevent the harmful effect
2Illumination intensity
If green quantum dots are used to emit green light, then color reproducibility is improved, but device complexity increases
Solution Approach 1:
The patent applies green quantum dots that serve multiple functions: they provide sharp emission peaks for excellent color reproducibility, maintain high quantum efficiency for brightness, and are compatible with standard blue LED excitation sources. This multi-functionality allows a single material to address multiple performance requirements without increasing overall device complexity
Solution Approach 2:
The patent merges the advantages of quantum dots (sharp emission, high efficiency) with the established blue LED technology platform. By combining green quantum dots with conventional blue LEDs and red phosphors, the invention integrates advanced materials into an existing device architecture, achieving enhanced color reproducibility without proportionally increasing device complexity
3Illumination intensity
If conventional green phosphors are used to emit green light, then device complexity is reduced, but light extraction efficiency decreases
Solution Approach 1:
The patent changes the emission spectrum parameter from broad (conventional phosphors) to narrow (quantum dots). This parameter change in the emission profile allows for better spectral matching with color filter transmission peaks, thereby improving light extraction efficiency and reducing attenuation through the display stack
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 use of KSF and MGF phosphors results in high luminous efficiency with narrow emission peaks, allowing for high color purity and improved light extraction efficiency through color filters, addressing the issue of secondary absorption and enhancing overall device performance.
Implementation Method 1
green quantum dots that emit a green light by absorbing part of the blue light emitted from the light emitting element
Implementation Method 2
particles of a red phosphor to absorb a portion of the blue light emitted from the light emitting element and emit a red light
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A light emitting device includes a light emitting element adapted to emit blue light, quantum dots that absorb part of the blue light emitted from the light emitting element to emit green light, and at least one of a KSF phosphor adapted to absorb part of the blue light emitted from the light emitting element to emit red light and a MGF phosphor adapted to absorb part of the blue light emitted from the light emitting element to emit red light.