Spectral characterization of LiYbF₄ upconverting nanoparticles

Area of Science:

• Materials Science
• Nanotechnology
• Photonics

Background:

• Recent advancements in Yb³⁺-based upconverting rare-earth nanoparticles (RENPs) necessitate further investigation into their spectral properties.
• Yb³⁺-doped RENPs are crucial for applications requiring efficient light conversion and emission tuning.

Purpose of the Study:

• To systematically explore the spectral features of LiYbF₄:RE³⁺/LiYF₄ core/shell RENPs doped with Tm³⁺, Er³⁺, or Ho³⁺.
• To investigate the tunability of upconversion emissions and the influence of doping concentration and excitation power density.

Main Methods:

• Synthesis and characterization of LiYbF₄:RE³⁺/LiYF₄ core/shell RENPs.
• Systematic exploration of spectral features including photoluminescence across UV to NIR regions.
• Analysis of upconversion photon order and average lifetime using steady-state power plots and photoluminescence decay studies.

Main Results:

• Tm³⁺-doped RENPs exhibited tunable UV to NIR photoluminescence with dominant high-photon-order upconversion.
• Er³⁺- and Ho³⁺-doped RENPs showed tunable green and red upconversion emissions.
• Cross-relaxation processes at higher doping concentrations influenced upconversion photon order and lifetime, promoting four- and five-photon emission in Tm³⁺-RENPs.

Conclusions:

• LiYbF₄:RE³⁺/LiYF₄ RENPs effectively generate high-order upconversion emissions due to efficient Yb³⁺ excitation energy confinement and funneling.
• The high quantum yield and potential brightness of these RENPs make them suitable for applications like controlled drug delivery and optogenetics.
• These RENPs offer a promising platform for advanced photonic applications requiring tunable and efficient upconversion luminescence.