Thèses

Vendredi 24 Novembre 2023 à 10h00.

Scintillation pathways in halide perovskite nanocrystals in liquid and solid media

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Directeur de thèse / thesis director :

Christophe DUJARDIN et Benoit MAHLER

Membres du jury / jury members :

Peter REISS
Anna VEDDA
Emmanuel BENICHOU
Aurélie BESSIERE
Anne Laure BULIN
Christophe DUJARDIN
Benoit MAHLER
Cuong DANG

Résumé / Abstract :

The presented work portrays the performances of lead halide perovskite nanocrystals (LHPNCs) as scintillators, either in a liquid or solid form. In particular, we focus on overcoming the issues induced by the small Stokes shift of such nanostructures, since the resulting high probability of self-absorption of the emitted light increases with the nanoparticles concentration; nevertheless, increasing the quantity of matter would benefit the overall system’s stopping power towards ionizing radiations, and thus the emission and detection efficiency. As a first approach, liquid scintillation appears as an interesting opportunity to study the interaction between colloidal perovskite nanocrystals and their surrounding medium: in particular, we focus on the energy deposition mechanism and on eventual energy transfers occurring between the dispersed nanocrystals and the surrounding solvent. As a matter of facts, if the excitation energy is deposited in the solvent and then transferred to the colloids, similarly to what happens in traditional organic liquid scintillators, this would artificially increase the overall system’s Stokes shift: an intense light emission from the perovskite nanostructures could thus be obtained without the need to excessively increase their concentration. A similarly conceived approach is their coupling with a surrounding partner material, like a bulk crystal or similar perovskite nanostructures with slightly different bandgaps. The latter’s role would be to collect the incoming ionizing radiation, modulate it and transfer it to the chosen final emitter, once again increasing the overall system’s Stokes shift.

In this presentation we will thus discuss about LHPNCs scintillation performances and energy deposition mechanisms, as well as strategies for their Stokes shift engineering.

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