Abstract
Upconverting materials have achieved great progress in recent years, however, it remains challenging for the mechanistic research on new upconversion strategy of lanthanides. Here, a novel and efficient strategy to realize photon upconversion from more lanthanides and fine control of lanthanide donor–acceptor interactions through using the interfacial energy transfer (IET) is reported. Unlike conventional energy‐transfer upconversion and recently reported energy‐migration upconversion, the IET approach is capable of enabling upconversions from Er3+, Tm3+, Ho3+, Tb3+, Eu3+, Dy3+ to Sm3+ in NaYF4‐ and NaYbF4‐based core–shell nanostructures simultaneously. Applying the IET in a Nd–Yb coupled sensitizing system can also enable the 808/980 nm dual‐wavelength excited upconversion from a single particle. More importantly, the construction of IET concept allows for a fine control and manipulation of lanthanide donor–acceptor interactions and dynamics at the nanometer‐length scale by establishing a physical model upon an interlayer‐mediated nanostructure. These findings open a door for the fundamental understanding of the luminescence dynamics involving lanthanides at nanoscale, which would further help conceive new scientific concepts and control photon upconversion at a single lanthanide ion level.
Highlights
Introduction nomena likeBrownian motion.[7]
The success in experimental synthesis of high quality nanostructured particles has got access into the spatial distribution of lanthanides at nanoscale or even at the sub-nanometer-length scale.[1a,3] the search for new mechanistic and experimental strategy to realize efficient photon upconversion from more lanthanides and pump schemes would make a substantial contribution to both fundamental research and practical application of upconversion materials
We have experimentally demonstrated that interfacial energy transfer is an efficient and more general strategy for achieving the photon upconversion from a series of lanthanides
Summary
As a proof of concept, we first investigated the photon upconversion performance from the conventionally studied lanthanide ions including Er3+, Tm3+, and Ho3+ through the IET strategy In this scheme, Yb3+ is adopted as the energy donor because of its capability in absorption of infrared excitation at 980 nm (2F5/2 ← 2F7/2 transition).[10] Yb3+ and luminescent activator A (A = Er, Tm, Ho) are spatially separated into different layers of the core–shell nanostructure, which were synthesized using a two-step coprecipitation method (Figure S1a, Supporting Information). The spectral results show a rapid decrease other than further increase in emission intensity at higher Yb3+ dopant concentration (>20 mol%) under 980 nm excitation (Figure S23, Supporting Information), being different from the result exhibited in Figure 5d where a third NaYF4:Nd layer grew on these core–shell particles This discovery confirmed that the presence of Yb3+ in shell sublattice can conduct the energy to particle surface, resulting in a severe luminescence quenching. 1.6–2.1 nm for effectively facilitating the energy transfer mediated upconversion
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