Friday, 01 July 2022

Highly luminescent scintillating hybrid nanocrystals that mimic natural light-harvesters

The results of the research published on Nature Communications
schema di un nanocristallo scintillatore

The Stokes shift is an important property of luminescent materials, defined as the energy difference between the absorption band maximum and the emission spectrum maximum. Large Stokes shift fast emitters show a negligible reabsorption of their luminescence, a feature highly desirable for several applications such as fluorescence imaging, solar-light managing, and fabricating sensitive scintillating detectors for medical imaging and high-rate high-energy physics experiments.

In the search for efficient and fast emitters with remarkably large Stokes shift, we tried to mimic natural light harvesting complex systems by engineering luminescent hybrid system such as the crystalline Metal-Organic Frameworks (MOFs), which constitute a solid platform to build materials wherein active struts perform tailored functions. Two ligands with complementary electronic properties are co-assembled generating hetero-ligand MOF nanocrystals. The rapid diffusion of the energy within the crystalline framework, similar to what happens during the photosynthesis in leaves, instantaneously activates the low energy emission, achieving a huge Stoke shift that avoids the reabsorption of emitted light even in macroscopic photonic devices such as scintillators.

These new emitters are realized by the researchers from the Department of Materials Science at University di Milano-Bicocca, as described in the paper “Highly luminescent scintillating hetero-ligand MOF nanocrystals with engineered Stokes shift for photonic applications” (doi: 10.1038/s41467-022-31163-0) recently published on Nature Communications (Impact Factor 17.694, Journal Citation Report (Clarivate Analytics, 2021)).

The material has been developed by a research team for the Department of Materials Science lead by professors Angelo Monguzzi, Angiolina Comotti, Franco Meinardi, Silvia Bracco, Piero Sozzani and Anna Vedda.