Photon upconversion through triplet exciton-mediated energy relay

Abstract

Exploration of upconversion luminescence from lanthanide emitters through energy migration has profound implications for fundamental research and technology development. However, energy migration-mediated upconversion requires stringent experimental conditions, such as high power excitation and special migratory ions in the host lattice, imposing selection constraints on lanthanide emitters. Here we demonstrate photon upconversion of diverse lanthanide emitters by harnessing triplet exciton-mediated energy relay. Compared with gadolinium-based systems, this energy relay is less dependent on excitation power and enhances the emission intensity of Tb3+ by 158-fold. Mechanistic investigations reveal that emission enhancement is attributable to strong coupling between lanthanides and surface molecules, which enables fast triplet generation (<100 ps) and subsequent near-unity triplet transfer efficiency from surface ligands to lanthanides. Moreover, the energy relay approach supports long-distance energy transfer and allows upconversion modulation in microstructures. These findings enhance fundamental understanding of energy transfer at molecule-nanoparticle interfaces and open exciting avenues for developing hybrid, high-performance optical materials.

Simultaneous enhancement of fluorescence intensity, thermometric sensitivity and SNR of upconversion thermometers via optical field localization

“…Lanthanide-doped upconversion nanoparticles (UCNPs) are extraordinary materials that continuously absorb multiple low-energy photons (usually NIR light) and emit high-energy photons (ultraviolet-visible light), and play essential roles in many areas such as solar cells, in vivo bioimaging, micro-lasers and nanoscale temperature sensing. [1][2][3][4] UCNPs have attracted considerable interest as temperature probes in recent years due to their unique advantages of non-contact measurement and accurate temperature detection of biological cells at the microor nano-scale. 5,6 Among the various sensing approaches, the fluorescence intensity ratio strategy based on thermally coupled levels transition of rare-earth ions has quickly become a research hotspot because of the advantages of rapid response, high sensitivity and spatial resolution.…”

Nanosecond kinetics of multiphoton upconversion in an optically trapped single microcrystal

“…Lanthanide-doped UC nanomaterials convert low-energy infrared photons into visible or ultraviolet emissions, 1 and have wide applications in the areas of biological engineering, 2,3 optical devices, [4][5][6][7][8][9] security, 10,11 super-resolution nanoscopes, 12,13 and lasers. [14][15][16] Their optical properties and emission behaviours can be effectively tuned by lanthanide doping, 17 crystal shape, 18 organic surface modifications, [19][20][21][22] and multilayer core-shell structures. 21,23 Traditionally, we understand the spectroscopic behaviours by exciting an assembly of MCs with various orientations.…”

“…[14][15][16] Their optical properties and emission behaviours can be effectively tuned by lanthanide doping, 17 crystal shape, 18 organic surface modifications, [19][20][21][22] and multilayer core-shell structures. 21,23 Traditionally, we understand the spectroscopic behaviours by exciting an assembly of MCs with various orientations. This gives strong emission signals but smooths out their individual behaviours such as anisotropic properties, 24,25 making the particle interaction difficult to study.…”

“…14–16 Their optical properties and emission behaviours can be effectively tuned by lanthanide doping, 17 crystal shape, 18 organic surface modifications, 19–22 and multilayer core–shell structures. 21,23…”

Degradation of upconverting nanoparticles in simulated fluids evaluated by ratiometric luminescence

“…Lanthanide-doped upconversion nanoparticles (UCNPs) have attracted increasing attention in the fields of materials science and biology due to their unique optical properties, such as large anti-Stokes spectral shift, high photostability and chemical stability, long lifetime, sharp emission band, and low toxicity. [1][2][3][4][5][6][7][8][9][10][11] The proposal and application of core-shell upconversion nanostructures is a milestone in the development of upconversion nanomaterials, which provides exciting new opportunities for their wide application in the biomedical, [12][13][14][15][16] environmental, and photocatalysis fields. [17][18][19][20][21] Notably, Liu's group proposed an energy transfer-mediated upconversion mechanism, in which activators without long-life intermediate energy states (Tb 3+ , Eu 3+ , Dy 3+ and Sm 3+ ) were doped in separated layers to achieve tunable upconversion emission by controlling gadolinium sublattice-mediated energy migration.…”