Low Phonon Lanthanide Chelates for Molecular Upconversion

光子上转换(UC)是一种越来越受关注的非线性多光子过程，它通过逐步吸收、能量传递和发射，利用低光子通量将近红外光有效地转换为可见光。掺杂到纳米粒子(如NaYF4)中的稀土离子(Ln3+)具有显著的发光特性，在量子传感技术、太阳能电池、红外量子计数器、防伪技术和生物医学成像等领域有着无与伦比的应用。尽管实现了工业应用，但由于量子产率低，Ln3+离子迁移，导致发射输出损失，溶解性差，材料加工性差，以及具有挑战性的官能化，上转换纳米粒子在更广泛和未来的长期使用中受到限制。因此，开发含有稀土离子的离散分子在溶液中提供UC过程是一个非常受欢迎的目标，但大多数此类分子仅限于自组装的动力学不稳定的系统，以及那些遭受振动失活过程的系统，因此需要低温才能操作。为了克服这些挑战，我们建议使用和开发可溶于有机溶剂的螯合物，这些螯合物的化学结构具有低的键振动(声子)能。它们基于不完全凝聚的多面体倍半硅氧烷硅笼。分子上转换技术将成为分子成像领域的一项突破，并将为开发光学器件制造(包括太阳能电池)、分析光谱和生物成像的应用提供平台。在这个项目中，学生将在合成化学和光学光谱两个方面工作：1.开发能够从近红外到可见光和紫外光具有高效宽带UC发射的离散分子低声子基镧系化合物。2.利用时间门控光谱技术研究分子的光物理性质，以获得更灵敏和更稳健的读出信号。3.探索光子在光电子、UC器件和量子技术中的应用。EPSRC职权范围：物理科学及其在量子技术和能源主题中的应用

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