Quantum Dot Array Down-Conversion for High CRI White Light
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Solution Overview
Problem
Current solid-state lighting technologies, such as those using cerium doped YAG phosphors, achieve low Color Rendering Index (CRI) values, resulting in white light with poor quality, which is not comparable to the black body radiation and lacks the desired spectral sensitivity for human eyes.
Innovation Solution
The use of quantum dots in combination with photoluminescent compounds, arranged in arrays with specific configurations, to produce white light with high CRI by absorbing and re-emitting light from a blue or ultraviolet light source, minimizing energy loss through re-absorption and tailoring emission spectra.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If phosphor materials are used as down converter, then manufacturing cost is low and efficiency is high, but Color Rendering Index is low resulting in poor white light quality
Solution Approach 1:
The patent combines multiple materials with different emission characteristics (yellow phosphor, red phosphor, green quantum dots, blue quantum dots) into a composite down-conversion layer. This composite structure enables the system to achieve high CRI (>90) by covering all visible spectrum regions while maintaining manufacturing feasibility through solution processing and printing techniques.
2Manufacturing precision
If incandescent bulb is used, then white light quality is high comparable to black body radiation, but energy efficiency is low and lifetime is short
Solution Approach 1:
The patent changes the fundamental mechanism from thermal radiation (incandescent) to photoluminescence down-conversion. By using a blue LED pump source with down-conversion phosphors and quantum dots, the system achieves black-body-like spectral quality without the energy waste of heating, thereby achieving high CRI with high energy efficiency.
3Manufacturing precision
If quantum dots are used to improve CRI, then white light quality increases, but device complexity increases due to multiple components
Solution Approach 1:
The patent merges multiple down-conversion materials (yellow phosphor, red phosphor, green quantum dots, blue quantum dots) into a single integrated down-conversion layer that can be applied as one coating. This merging approach maintains high CRI while simplifying the device structure and manufacturing process.
Solution Approach 2:
The down-conversion layer serves multiple functions simultaneously: converting blue LED light to yellow, red, green, and blue wavelengths; achieving high CRI; and enabling full-spectrum coverage. This multi-functionality reduces the need for separate components and simplifies the overall device architecture.
4Duration of action of moving object
If blue LED with yellow phosphor is used, then efficiency is high and lifetime is long, but Color Rendering Index is low between 70 to 80
Solution Approach 1:
The patent creates a composite down-conversion system combining yellow phosphor (YAG:Ce), red phosphor (CaAlSiN3:Eu), green quantum dots (CdSe), and blue quantum dots (CdS) with the blue LED pump source. This composite structure maintains the high efficiency and long lifetime of LED technology while achieving CRI >90 by adding red and green emission components to the yellow phosphor system.
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 approach achieves high-quality white light with a CRI exceeding 90, closely mimicking black body radiation and optimizing spectral sensitivity for human eyes, while being cost-effective and versatile for various lighting applications.
Implementation Method 1
The use of quantum dots in combination with photoluminescent compounds, arranged in arrays with specific configurations, to produce white light with high CRI by absorbing and re-emitting light from a blue or ultraviolet light source
Implementation Method 2
The use of quantum dots in combination with photoluminescent compounds, arranged in arrays with specific configurations, to produce white light with high CRI by absorbing and re-emitting light from a blue or ultraviolet light source
Data Source
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AI summary
The present invention relates inter alia to an array comprising i times j array elements, wherein the array elements may comprise at least one quantum dot and/or at least one photoluminescent compound. Further the present invention relates to devices comprising these arrays. The arrays and devices can be used to generate white light with high color purity.