Switching to the brighter lane: pathways to boost the absorption of lanthanide-doped nanoparticles

Lanthanide-doped nanoparticles (LNPs) are spreadily colonizing several fields, such as biological (multimodal) imaging, photodynamic therapy, volumetric encoding displays, and photovoltaics. Yet, the electronic transitions of lanthanide ions obey the Laporte rule, which dramatically cripples their light absorption capabilities. As a result, the brightness of these species is severely curbed. This intrinsically poor absorption capabilities is the fundamental obstacle for untapping the full potential of LNPs in several the fields. Among others, the three most promising physicochemical approaches challenge arisen during the last two decades to face the challenge of increasing LNP absorption are plasmonic enhancement, organic-dye sensitization, and coupling with semiconductors. The fundamental basis, remarkable highliths, and comparative achievements of each of these pathways for absorption betterment are critically discussed in this minireview, also incuding a detailed discussion of the exciting perspectives ahead.