Core/Shell Upconversion Nanophosphor for Red Light Emission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current upconversion nanophosphors face challenges in emitting intense red light when excited by infrared wavelengths other than 980 nm, leading to reduced luminescence intensity and potential tissue damage due to deep penetration of 980-nm infrared light, and existing materials struggle to efficiently convert near-infrared light into visible red light for applications like bioimaging and security.
Innovation Solution
A tetragonal fluoride core/multi-shell upconversion nanophosphor structure, specifically LiEr1-x-yLyF4:Tm3+x with surrounding shells, is synthesized using a method involving precursor mixing and heat treatment, allowing emission of red light under 800-nm, 980-nm, and 1530-nm infrared excitation, enhancing luminescence intensity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If 980-nm infrared light is used as excitation light, then upconversion nanophosphors can emit green or blue light, but the infrared light penetrates deeply into body parts causing potential tissue damage and the emitted light does not penetrate well for bioimaging applications
Solution Approach 1:
The patent changes the excitation wavelength parameter from 980 nm to 800 nm infrared light, which fundamentally alters the energy transfer pathway. This parameter change enables the nanophosphor to emit red light instead of green/blue light, while using 800 nm light (which is less absorbed by water molecules) to avoid deep tissue penetration and associated tissue damage risks
Solution Approach 2:
The patent employs a composite core-shell structure with specific doping compositions. The core contains LiEr1-x-yLyF4:Tm3+x while the shell contains LiGd1-p-qMqF4:Yb3+p and LiY1-r-s-tNtF4:Nd3+r,Yb3+s. This composite structure enables efficient energy transfer from 800 nm infrared light to produce intense red light emission while maintaining biocompatibility
2Illumination intensity
If energy transfer from activator to co-sensitizer is used to achieve red light emission, then red light can be emitted, but the luminescence intensity is reduced
Solution Approach 1:
The patent segments the energy transfer process into distinct functional zones within the core-shell structure. The core (LiEr1-x-yLyF4:Tm3+x) handles initial light absorption and energy localization, while the shell (LiGd1-p-qMqF4:Yb3+p and LiY1-r-s-tNtF4:Nd3+r,Yb3+s) manages efficient energy transfer to the red-emitting centers. This segmentation prevents energy loss by optimizing each stage of the energy transfer pathway
Solution Approach 2:
The patent applies local quality by doping specific elements at specific locations within the core-shell structure. Thulium (Tm3+) is localized in the core for red emission, while ytterbium (Yb3+) and neodymium (Nd3+) are positioned in the shell for efficient energy absorption and transfer. This spatial distribution of dopants optimizes energy transfer efficiency and maximizes red light emission intensity
3Use of energy by moving object
If 980-nm infrared light is used for excitation, then upconversion can occur, but water molecules absorb the light causing temperature increase that may kill cells or damage tissues
Solution Approach 1:
The patent changes the excitation wavelength parameter from 980 nm to 800 nm. This parameter change is critical because 800 nm infrared light is less strongly absorbed by water molecules compared to 980 nm light. Consequently, the nanophosphor can still efficiently absorb 800 nm infrared light for upconversion while causing minimal heating of surrounding tissues, thereby avoiding cell death and tissue damage
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 nanophosphor achieves high-purity red light emission with increased intensity and photostability, suitable for bioimaging and security applications, while minimizing biohazard risks due to reduced cell absorption and improved bio-transmittance, offering improved security and sensing capabilities.
Implementation Method 1
An upconversion nanophosphor refers to a phosphor including luminescent nanoparticles having a small diameter equal to or less than 100 nm and capable of absorbing low-energy light and emitting high-energy light
Implementation Method 2
emits light due to 4f-4f electronic transition of the trivalent lanthanide ions, and thus exhibits luminescence of a unique color based on the type of the lanthanide element
Implementation Method 3
energy from erbium (Er) used as an activator is transferred to manganese (Mn), or energy from holmium (Ho) used as an activator is transferred to cerium (Ce) used as a co-sensitizer
Implementation Method 4
A phosphor generally has a structure in which an inorganic base material is doped with a lanthanide element, and an upconversion nanophosphor generally absorbs infrared light and emits visible light
Data Source
AI summary
Provided is a fluoride nanophosphor using, as cores, luminescent nanoparticles expressed by Chemical Formula 1.LiEr1-x-yLyF4:Tm3+x [Chemical Formula 1](In Chemical Formula 1, x is a real number satisfying 0≤x≤0.3, y is a real number satisfying 0≤y≤0.8 and is selected within a range satisfying 0≤x+y≤0.9, and L is any one selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), ytterbium (Yb), lutetium (Lu), and a combination thereof.)