Selectively Manipulating Interactions between Lanthanide Sublattices in Nanostructure toward Orthogonal Upconversion

Smart control of ionic interactions is a key factor to manipulate the luminescence dynamics of lanthanides and tune their emission colors. However, it remains challenging to gain a deep insight into the physics involving the interactions between heavily doped lanthanide ions and in particular between the lanthanide sublattices for luminescent materials. Here we report a conceptual model to selectively manipulate the spatial interactions between erbium and ytterbium sublattices by designing a multilayer core–shell nanostructure. The interfacial cross-relaxation is found to be a leading process to quench the green emission of Er3+, and red-to-green color-switchable upconversion is realized by fine manipulation of the interfacial energy transfer on the nanoscale. Moreover, the temporal control of up-transition dynamics can also lead to an observation of green emission due to its fast rise time. Our results demonstrate a new strategy to achieve orthogonal upconversion, showing great promise in frontier photonic applications

Multichannel Control of PersL/Upconversion/Down-Shifting Luminescence in a Single Core–Shell Nanoparticle for Information Encryption

Persistent luminescence (PersL) has been attracting substantial attention in diverse frontier applications such as optical information security and in vivo bioimaging. However, most of the reported PersL emissions are based on the dopants instead of the host matrix, which also plays an important role. In addition, there are few works on the PersL-based multifunctional nanoplatform in nanosized materials. Here, we report a class of novel nanostructure designs with PersL, upconversion, and down-shifting luminescence to realize the fine-tuning of emission colors under different excitation modes including steady-state irradiation, time-gating, and PersL generation. Blue, orange, and green emissions were easily achieved in such a single nanoparticle under suitable excitation modes. Moreover, the physical origin of the PersL of the CaF2 matrix was discussed by simulating the energy band structure with CaxFy defects. Our results provide new opportunities for the design of a new class of multifunctional materials, showing great promise in the field of information encryption security and multilevel anticounterfeiting

Enabling Nonthermally Coupled Upconversion in a Core–Shell–Shell Nanoparticle for Ultrasensitive Nanothermometry and Anticounterfeiting

Luminescence intensity ratio (LIR)-based thermometry has the advantages of high relative sensitivity, fast temperature response, and high spatial resolution. However, the current LIR-based systems are mainly based on thermally coupled energy levels, which have low sensitivity due to the intrinsic limitation of the Boltzmann distribution theory. Here, we report a design of a core–shell–shell nanostructure to improve the thermal sensitivity by using the nonthermally coupled upconversion emissions. Ho3+ and Tm3+ were selected as emitters and spatially separated by an inert interlayer. The upconverted Tm3+ emissions show a dramatical thermal enhancement while the Ho3+ emissions show a decline with increasing temperature, resulting in a huge LIR (695 nm/645 nm) contrast and thereafter a high relative sensitivity (9.78% K–1 at room temperature). In addition, this nanostructure design presents a color change from red to blue at different excitation powers and also from red to green by tuning the excitation laser pulse widths. These results hold great potential in the field of noncontact ultrasensitive temperature sensors and multimodel anticounterfeiting

Supplementary document for Efficient and Tunable Photoluminescence for Terbium Doped Rare-Earth-based Cs2NaYCl6 Double Perovskite - 6036993.pdf

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