Interface-Dependent Radiative Lifetimes of Yb³⁺, Er³⁺ Co-doped Single NaYF₄ Upconversion Nanowires

Area of Science:

• Materials Science
• Nanotechnology
• Photonics

Background:

• Upconversion nanomaterials are crucial for photonic applications.
• Their performance depends on radiative lifetimes influenced by local environments.

Purpose of the Study:

• To investigate the impact of dielectric interfaces on the photoluminescence lifetime of upconversion nanomaterials.
• To explore applications in nanoscale temperature sensing and control.

Main Methods:

• Synthesis of hexagonal (β-phase) sodium-yttrium-fluoride (NaYF4) nanowires doped with erbium (Er3+) and ytterbium (Yb3+) ions.
• Utilized a single-beam laser trapping instrument with a variable-temperature stage to control nanowire distance from a substrate.
• Measured spontaneous photoluminescence lifetime of the Er3+ 4S3/2 → 4I15/2 transition.

Main Results:

• Photoluminescence lifetime of Er3+ ions in NaYF4 nanowires varied by over 60% with distance from a dielectric interface.
• Lifetime increased by a factor of 1.62 ± 0.01 as distance increased from ~0 nm to ~40 μm.
• Temperature changes between 25-50 °C caused minor lifetime variations (≤10%).

Conclusions:

• Local dielectric environments significantly influence upconversion nanomaterial radiative lifetimes.
• Classical electromagnetic coupling explains the observed distance dependence.
• NaYF4 nanowires show potential for nanoscale temperature control and probing.