Ce3+-Activated Cyan Phosphor for High-Irradiance Lighting
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Solution Overview
Problem
Conventional phosphors with Eu2+ as an activator element are limited by quenching effects at low irradiance levels, while Ce3+-activated phosphors face quenching at higher irradiance levels, restricting their efficiency in human-centric lighting applications.
Innovation Solution
A phosphor with the molecular formula EA3−xRExD2+yE12−yN20−zOz:M, where EA is divalent, RE is a rare earth element, D is trivalent, E is tetravalent, and M is an activator, is developed, which maintains efficiency at high irradiance levels and emits in the cyan wavelength range, enhancing melanopic efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If Eu2+ is used as an activator element in phosphor, then the phosphor can be used at low irradiance levels, but quenching effects occur even at low irradiance levels of around 100 mW/mm2, limiting efficiency
Solution Approach 1:
The patent changes the activator element parameter from Eu2+ to Ce3+, which fundamentally alters the photophysical properties of the phosphor. Ce3+ activation shifts the emission mechanism and reduces quenching effects, allowing efficient operation at high irradiance levels that would cause quenching in Eu2+-activated phosphors.
Solution Approach 2:
The patent employs a composite phosphor system with specific host materials (such as Sr2Si5N8, Ba2Si5N8, or Ca2Si5N8) combined with Ce3+ activator. This composite structure optimizes both the host lattice properties and activator characteristics to achieve high efficiency at high irradiance levels while maintaining cyan wavelength emission.
2Loss of energy
If Ce3+ is used as an activator element in phosphor, then quenching effects are reduced at higher irradiance levels, but the emission wavelength may not optimally stimulate melanopsin photoreceptor
Solution Approach 1:
The patent optimizes the emission wavelength parameter by selecting specific host materials and Ce3+ concentration levels. The host material composition and crystal structure are tuned to position the Ce3+ emission peak in the cyan range (460-520 nm), which optimally stimulates melanopsin photoreceptors while maintaining low quenching characteristics.
Solution Approach 2:
The patent achieves local optimization of the emission spectrum by controlling the local crystal field environment around Ce3+ ions through specific host material selection and doping concentrations. This local structural control ensures that the emission wavelength is precisely tuned for melanopsin stimulation while maintaining the low quenching properties of Ce3+.
3Illumination intensity
If conventional phosphors are used for human-centric lighting, then they can provide illumination, but they fail to efficiently stimulate the photoreceptor melanopsin due to wavelength limitations
Solution Approach 1:
The patent utilizes color change by selecting Ce3+-activated phosphors that emit in the cyan wavelength range (460-520 nm). This specific color emission range is optimized for stimulating melanopsin photoreceptors, which are most sensitive in this region, thereby improving human-centric lighting effects while maintaining adequate illumination.
Solution Approach 2:
The patent employs composite phosphor systems where the host material and Ce3+ activator are specifically selected and combined to achieve both adequate illumination and optimized melanopsin stimulation. The composite structure allows simultaneous optimization of overall light output and spectral characteristics for human-centric lighting applications.
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 new phosphor achieves efficient electromagnetic radiation emission with a dominant wavelength of less than 550 nanometers even at high irradiance, outperforming conventional phosphors in stimulating the photoreceptor melanopsin, thus improving human-centric lighting effects.
Implementation Method 1
the host lattice changes the electronic structure of the activator element in such a way that electromagnetic radiation of an excitation wavelength absorbed by the phosphor causes an electronic transition from a ground state to an excited state in the phosphor. By emitting electromagnetic radiation with an emission spectrum, the phosphor returns to the ground state.
Data Source
AI summary
A phosphor with the molecular formula EA3−xRExD2+yE12−yN20−zOz:M is specified, where EA is an element or a combination of elements from the group of divalent elements, RE is a rare earth element, D is an element or a combination of elements from the group of trivalent elements, E is an element or a combination of elements from the group of tetravalent elements, M is an activator element or a combination of activator elements, 0≤x≤3, 0≤y≤12 and z=y−x, wherein z≥0. Further, a method for producing a phosphor and a radiation emitting component are specified.