Tailoring Plasmonic Enhanced Upconversion in Single NaYF4:Yb(3+)/Er(3+) Nanocrystals.

Ya-Lan Wang,Hai-Yang Li,Zhenyu Zhang,Amber Johnson,Andrea Alù,Li-Xiang Xu,Nasim Mohammadi Estakhri,Chih-Kang Shih,Qu-Quan Wang

doi:10.1038/srep10196

Abstract

By using silver nanoplatelets with a widely tunable localized surface plasmon resonance (LSPR), and their corresponding local field enhancement, here we show large manipulation of plasmonic enhanced upconversion in NaYF4:Yb3+/Er3+ nanocrystals at the single particle level. In particular, we show that when the plasmonic resonance of silver nanolplatelets is tuned to 656 nm, matching the emission wavelength, an upconversion enhancement factor ~5 is obtained. However, when the plasmonic resonance is tuned to 980 nm, matching the nanocrystal absorption wavelength, we achieve an enhancement factor of ~22 folds. The precise geometric arrangement between fluorescent nanoparticles and silver nanoplatelets allows us to make, for the first time, a comparative analysis between experimental results and numerical simulations, yielding a quantitative agreement at the single particle level. Such a comparison lays the foundations for a rational design of hybrid metal-fluorescent nanocrystals to harness the upconversion enhancement for biosensing and light harvesting applications.

Highlights

By using silver nanoplatelets with a widely tunable localized surface plasmon resonance (LSPR), and their corresponding local field enhancement, here we show large manipulation of plasmonic enhanced upconversion in NaYF4:Yb3+/Er3+ nanocrystals at the single particle level
We track single fluorescent particles before and after coupling to triangularly shaped silver nanoplatelets (AgNPs), whose plasmon resonance is widely tunable by adjusting the lateral length
The sample was fabricated with a three-step process: first, the upconversion nanocrystals, originally in ethanol solution with a concentration of 1 mg/ml, were spun on the marked silicon substrate with native oxide

Summary

Results

For this nanocrystal, we observe a 22-fold enhancement of PL due to the local field enhancement by the AgNPs. For this nanocrystal, we observe a 22-fold enhancement of PL due to the local field enhancement by the AgNPs This enhancement is different among emitters, since it is at the single emitter level (as shown in Supporting Information Fig. S2). We have investigated the upconversion enhancement of NaYF4:Yb3+/Er3+ nanocrystals at the single particle limit, based on LSPR supported by AgNPs. We experimentally obtain an enhancement of over 22 folds when the LSPR of AgNPs resonates with the excitation wavelength, consistent with our numerical calculations and theoretical modeling. This strategy for PL enhancement provides exciting venues for applications in biosensing and solar cell technology

Methods

Author Contributions

Additional Information