Optical properties of lanthanide dyes for spectral conversion encapsulated in porous silica nanoparticles

Lanthanide based dyes belong to one of the most promising fields of photovoltaic research, combining high quantum yields and large spectral shift. However, many challenges are faced when working with lanthanide dyes for spectral conversion: their thermal and chemical stability, which can greatly influence the shelf-life of the dyes; the absorption band position, which depends on the organic part of the dye, the so called "antenna"; self-quenching mechanisms, which lead to a photoluminescence emission loss. The chemical composition of the surrounding environment of the dyes has a fundamental role in their properties. In this paper, the optical and PLQY (photoluminescence quantum yield) properties of an europium-based dye embedded in a silica matrix are reported. The in-house synthesized dye consists of a bis(2-(diphenylphosphino)phenyl)ether oxide (DPEPO) ligand and three hexafluoroacetylacetonate (hfac) co-ligands coordinating a central europium ion. The dye has been included in porous core-shell particles, to study its optical properties once embedded in a solid dielectric matrix. The optical properties of the resulting samples have been characterized by photoluminescence emission and PLQY measurements. The results have been compared with data obtained from a commercially available dye (BASF Lumogen family) in similar conditions.