Fonctions Optiques pour les Technologies de l’informatiON - CNRS UMR 6082

Since September 2020, the Foton Institute has been welcoming two visual artists as part of an Art & Science residency within the laboratory (...)

(Science 2022) Colloidal lead halide perovskite nanocrystals are of interest as photoluminescent quantum dots (QDs) whose properties depend on their size and shape. We report a room-temperature synthesis of monodisperse, isolable, spheroidal APbBr₃ QDs (“A” indicates cesium, formamidinium, and methylammonium) that are size tunable from 3 to >13 nanometers. The kinetics of both nucleation and growth are temporally separated and substantially slowed down. QDs of all these compositions exhibit up to four excitonic transitions in their linear absorption spectra, and we demonstrate experimentally and theoretically that the size-dependent confinement energy for all transitions is independent of the A-site cation.

(Science 2022) Realizing solution-processed heterostructures is a long-enduring challenge in halide perovskites because of solvent incompatibilities that disrupt the underlying layer. By solvent fine tuning, we could grow phase-pure two-dimensional (2D) halide perovskite bilayer stacks of the desired composition, thickness, and bandgap onto 3D perovskites without dissolving the underlying substrate. Thickness dependence of the 2D perovskite layer reveals the anticipated trends for n-i-p and p-i-n architectures, which is consistent with band alignment and carrier transport limits for 2D perovskites. We measured a photovoltaic efficiency of 24.5%, with exceptional stability of T99 (time during which the efficiency remains above 99% of its initial value) of >2000 hours, implying that the 3D/2D bilayer inherits the intrinsic durability of 2D perovskite without compromising efficiency.

The jury of the French Physical Society (SFP) Grand Prix has awarded the Jean Ricard Prize 2022 to Jacky EVEN, professor at INSA Rennes, physicist at the UMR Institut FOTON, and senior member of (...)

The paper describes the first ultrafast direct measurement of structural dynamics and heat release under high excitation in 2D perovskites. These materials are used in highly efficient perovskite (...)