Light-harvesting Europium architectures: from molecules to functional materials for versatile luminescent applications

The present thesis is dedicated to the synthesis of europium-based luminescent antenna complexes and oxoclusters and to their intriguing photonic applications, peculiarly triggered by ultraviolet photons. Specifically, their photophysical behaviour raises them as eligible candidates for contactless Luminescent Molecular Thermometers (LMTs) and for the currently blooming Luminescent Solar Concentrators (LSCs) scenario. To this purpose, a pentanuclear Eu3+ oxocluster, whose stoichiometry is described by Eu5(OH)5(DBM)10 where DBM indicates the -diketonate ligand dibenzoylmethanide, was synthesized and crystallographically isolated. Additionally, two discrete monometallic analogues, one consisting of Eu(DBM)3(H2O)2 and the other of Eu(DBM)3(DME), where DME represents the ancillary bischelate dimethoxyethane, were prepared in order to compare their luminescent features with the increasing number of metallic atoms in the inner core. The project is then declined into other three phases, namely the characterization of the realized luminescent molecules, their optimized embedding into PMMA matrix for the development of photoluminescent functional materials in a thin film configuration and, finally, the probing of their spectroscopical and performative responses. These latter aspects encompassed testing all the doped red-emitting films for their luminescence-temperature correlation properties and functionality as LSC devices. Exploring the temperature interval from 83 to 333 K, the relative thermal sensitivity parameter, Sr, exhibited values major than 1 (generally assumed as a quality criterion for these thermometers) approximately from 220 K to the end of the investigated thermal operative range, thus embracing the physiological temperature window. Furthermore, taking advantage of a recently-devised home-made set up, the electrical outputs of silicon photovoltaic cells, edge-coupled to the LSC perimeter, are evaluated under simulation of solar irradiation. Although further work is necessary to glean a deeper comprehension, these preliminary studies pave the way for the potential exploitation of dibenzoylmethanide Eu3+ systems for temperature sensing and as active components for LSCs, without noticing strong deviations among the investigated species’ performances.