Polysulfide Upconversion Phosphor for High Efficiency Luminescence
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Solution Overview
Problem
Current upconversion phosphors have limited luminescence efficiency, particularly for rare earth sulfides, which are not effective substrates for traditional Yb3+ sensitized upconversion luminescence, and existing materials face challenges in achieving high quantum efficiency and stability.
Innovation Solution
A polysulfide upconversion phosphor with a general formula of mA2S·nBS·kC2-xS3:Dx, using polysulfide as a substrate and rare earth ions as activators, which achieves high luminescence efficiency and stability, enabling emission of ultraviolet, blue, green, red, and near-infrared light through multi-wavelength excitation, and has a low phonon energy and low-symmetry crystal system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rare earth sulfide is used as substrate for upconversion luminescence, then chemical stability and thermal stability are improved, but luminescence efficiency is insufficient due to high covalent bond properties and complex preparation technology
Solution Approach 1:
The patent uses polysulfide composite materials (CaAlSiN3:Eu2+ and Sr2Si5N8:Eu2+) as substrates for upconversion luminescence. These composite materials combine the advantages of chemical stability from sulfide materials with improved luminescence efficiency, avoiding the high covalent bond properties that hinder upconversion in traditional rare earth sulfides. The composite structure enables both stability and manufacturability.
2Use of energy by moving object
If conventional photoluminescence materials are used, then luminescence efficiency is high, but inability to convert infrared light into ultraviolet or visible light limits application in biomedicine and solar cells
Solution Approach 1:
The patent merges conventional photoluminescence materials with upconversion luminescence materials to create a hybrid system. The polysulfide substrate doped with rare earth ions (Yb3+, Er3+, Tm3+, Ho3+) combines the high luminescence efficiency of conventional materials with the infrared-to-visible light conversion capability of upconversion materials, enabling both high efficiency and broad application range in biomedicine, solar cells, and anti-counterfeiting.
3Loss of energy
If fluoride substrate is used for upconversion luminescence, then low phonon energy is achieved improving luminescence efficiency, but harsh preparation environment causes equipment corrosion and environmental pollution
Solution Approach 1:
The patent replaces expensive and environmentally harmful fluoride substrates with polysulfide substrates that have comparable low phonon energy properties. The polysulfide materials (CaAlSiN3:Eu2+ and Sr2Si5N8:Eu2+) offer similar energy loss characteristics but with better environmental compatibility, easier preparation conditions, and no equipment corrosion issues, effectively substituting the harmful fluoride materials.
4Reliability
If oxide substrate is used, then chemical stability and simplicity of preparation are improved, but high phonon energy reduces upconversion luminescence efficiency
Solution Approach 1:
The patent changes the substrate material parameters from traditional oxides to polysulfides, which have fundamentally different phonon energy characteristics. The polysulfide substrates (CaAlSiN3:Eu2+ and Sr2Si5N8:Eu2+) possess low phonon energy similar to fluorides but with the chemical stability and preparation simplicity of oxides, effectively optimizing multiple parameters simultaneously for high-efficiency upconversion luminescence.
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 polysulfide upconversion phosphor exhibits higher luminescence efficiency than conventional NaYF4:Yb, Er, with the ability to achieve multi-wavelength excitation and safe infrared light excitation, reducing the need for protective equipment and expanding application scenarios.
Implementation Method 1
upconversion luminescence can convert infrared light into ultraviolet or visible light
Implementation Method 2
photoluminescence can be classified into conventional photoluminescence and upconversion luminescence
Data Source
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AI summary
The present invention relates to a polysulfide upconversion phosphor, and belongs to the field of new optical function materials. The phosphor uses polysulfide as a substrate and rare earth ions as activators, and has a general formula of composition: mA2S·nBS·kC2-xS3:Dx. The upconversion phosphor provided by the present invention can emit ultraviolet, blue, blue-green, green, red and near-infrared light when excited by near infrared light at 750-1650 nm. Because the upconversion phosphor provided by the present invention uses polysulfide with low phonon energy and symmetry as a substrate material, and optimizes rare earth ions to be doped into the matrix material as luminescence centers, the upconversion phosphor has higher upconversion luminescence efficiency and safety and wider application range compared with industrial NaYF4:Yb, Er material.