Cerium-Activated Oxonitridoaluminosilicate Phosphor for LED White Light
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Solution Overview
Problem
Existing white light illumination systems using light-emitting diodes face challenges in generating consistent white light due to variations in tone and luminance, and phosphor-converted systems suffer from efficiency issues, particularly when using UV-to-blue radiation conversion.
Innovation Solution
The use of cerium(III)-activated alkaline earth oxonitridoaluminosilicate phosphors with a broad excitation band in the blue and UVA range, capable of efficiently converting primary radiation into yellow to red secondary radiation, is introduced, allowing for improved luminescence conversion efficiency and consistent white light production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If phosphor-converted illumination systems use UV-to-blue radiation conversion, then white light can be generated, but efficiency is reduced due to energy losses in conversion
Solution Approach 1:
The patent changes the excitation parameters of the phosphor material by developing a broad-band excitation phosphor that can be excited by both UV and blue light with high efficiency. This allows optimization of the excitation wavelength to match the LED emission spectrum, maximizing the overlap between pump light and phosphor absorption, thereby improving luminescence conversion efficiency and reducing energy losses.
Solution Approach 2:
The patent employs composite phosphor formulations combining multiple phosphor materials with complementary emission spectra. This includes yellow-emitting phosphors (such as YAG:Ce) and red-emitting phosphors (such as CaAlSiN3:Eu), creating a composite luminescent layer that achieves high conversion efficiency across the visible spectrum while minimizing energy losses through synergistic effects of the constituent materials.
2Illumination intensity
If visibly colored light emitting diodes are used to generate white light, then illumination can be provided, but consistent white light tone cannot be achieved due to variations in tone and luminance
Solution Approach 1:
The patent uses phosphor materials as intermediary converters that transform the narrow-band emission of LEDs into broad-spectrum white light. By positioning phosphors between the LED source and the output, the system achieves consistent white light tone because the phosphors' broad emission spectra mask the variations in LED luminance and tone, providing stable color rendering regardless of LED performance fluctuations.
Solution Approach 2:
The patent develops phosphor materials with universal excitation characteristics that can be efficiently excited by multiple LED types (UV, blue, and violet LEDs). This multi-functionality allows the same phosphor formulation to work across different LED platforms, ensuring consistent white light output characteristics regardless of the specific LED source used, thereby improving reliability and reducing tone variations.
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 solution provides a high-efficiency white light with improved color rendering and reduced energy losses, suitable for applications like traffic lighting, security lighting, and automated factory lighting, with a quantum efficiency of up to 90% and resistance to thermal quenching.
Implementation Method 1
a luminescent material comprising at least one phosphor capable of absorbing a portion of light emitted by the radiation source and emitting light of a wavelength different from that of the absorbed light
Implementation Method 2
A light-emitting diode as a radiation source is especially contemplated
Data Source
AI summary
An illumination system, comprising a radiation source and a luminescent material comprising at least one phosphor capable of absorbing a part of light emitted by the radiation source and emitting light of wavelength different from that of the absorbed light; wherein said at least one phosphor is a yellow red-emitting cerium(III)-activated alkaline earth oxonitridoaluminosilicate of general formula Ca1−x−yAxAl1+a−bBbSi1−aN3−aOa:Cey, wherein A selected from the group comprising beryllium, magnesium, strontium, barium, zinc, manganese, lithium, sodium, potassium, rubidium, praseodymium, samarium, europium, and B selected from the group comprising boron, gallium, scandium and wherein 0<x≦1; 0<y<0.2; 0.001<a<1 and 0.001<b<1 can provide light sources having high luminosity and color-rendering index, especially in conjunction with a light emitting diode as a radiation source. The red to yellow-emitting cerium(III)-activated alkaline earth oxonitridoaluminosilicate of general formula Ca1−x−yAxAl1+a−bBbSi1−aN3−aOa:Cey, wherein A selected from the group comprising beryllium, magnesium, strontium, barium, zinc, manganese, lithium, sodium, potassium, rubidium, praseodymium, samarium, europium, and B selected from the group comprising boron, gallium, scandium and wherein 0<x≦1; 0<y<0.2; 0.001<a<1 and 0.001<b<1 is efficiently excitable by primary radiation in the near UV-to-blue range of the electromagnetic spectrum.