Low Phonon Lanthanide Chelates for Molecular Upconversion

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Photon upconversion (UC) is an increasingly attractive nonlinear multiphoton process that effectively converts near infra-red light into visible light using low photon fluxes via stepwise absorption, energy transfer and emission. Lanthanide ions (Ln3+) doped into nanoparticles (e.g. NaYF4) exhibit remarkable UC properties with many unrivalled applications in e.g. quantum sensing technologies, solar cells, IR quantum counters, anticounterfeiting technologies and biomedical imaging. Despite implementation in industrial applications, upconverting nanoparticles are limited in wider and future long-term use due to low quantum yields, Ln3+ ion migration, leading to loss of emission output, poor solubility, poor material processability, and challenging functionalization. Developing discrete molecules containing lanthanide ions providing UC processes in solution thus represents a very highly sought-after goal, but most of such molecules are restricted to self-assembled kinetically unstable systems and those that suffer from vibrational deactivation processes and hence require cryogenic temperatures to operate.To overcome these challenges, we propose to use and develop organic solvent soluble chelates that are solution processable and whose chemical structures possess low bond vibrational (phonon) energies. These based on incompletely condensed polyhedral silsesquioxane silica cages. Molecular up-conversion technologies will constitute a breakthrough within molecular imaging and should provide a platform to develop applications in optical device fabrication (including solar cells), analytical spectroscopy and biological imaging.In this project, the student will work in both synthetic chemistry and optical spectroscopy to:1. Develop discrete molecular low phonon-based lanthanide compounds capable of exhibiting efficient broadband UC emission from the near infra-red to the visible and UV. 2. Study the photophysical properties of the molecules using time-gated spectroscopy techniques for more sensitive and robust readout signals. 3. Explore photonic applications in optoelectronic, UC device and quantum technologies. EPSRC remit: Physical Sciences with applications in the quantum technologies and energy themes