jp8b05992_si_001.pdf (2 MB)
In-Depth Analysis of Excitation Dynamics in Dye-Sensitized Upconversion Core and Core/Active Shell Nanoparticles
journal contribution
posted on 2018-07-16, 00:00 authored by Sergey Alyatkin, Elena Ureña-Horno, Bigeng Chen, Otto L. Muskens, Antonios G. Kanaras, Pavlos G. LagoudakisUpconversion nanoparticles
(UCNPs) combining both dye sensitization
and core/shell enhancement are of great interest for their ability
to boost the excitation efficiency of upconversion systems. Here,
we report and investigate a 20-fold upconversion luminescence enhancement
in dye-sensitized core/active shell UCNPs compared to that in nonsensitized
core-only UCNPs. We observe a two-component luminescence rise dynamics
in the upconversion kinetics of dye-sensitized UCNPs, distinctly different
from the one-component rise dynamics of the nonsensitized UCNPs. For
dye-sensitized UCNPs, the fast sub-microsecond component of the upconversion
luminescence rise time is attributed to the radiative pumping of Er3+ ions from the dye, whereas the slow sub-millisecond component
is due to the nonradiative energy transfer from the dye predominantly
to Yb3+ ions, followed by the energy migration and the
nonradiative energy transfer from Yb3+ to Er3+ ions. Our studies provide an insight into the interplay between
radiative and nonradiative energy transfer as well as into the role
of energy migration across the active shell of dye-sensitized core/active
shell UCNPs.