Description du projet
Un microscope holographique inégalé met en lumière les photomatériaux organiques
L’efficacité des cellules solaires s’est considérablement accrue au cours des dernières décennies. La réduction des coûts des matériaux sera essentielle pour une adoption plus large. L’utilisation de matériaux organiques et hybrides plutôt que de matériaux inorganiques conventionnels comme le silicium pourrait être la solution. Toutefois, leur morphologie hétérogène, essentielle à leur fonctionnalité, a rendu difficile la caractérisation expérimentale des processus ultra-rapides à l’échelle nanométrique qui s’y déroulent. Le projet HOLOFAST, financé par le CER, vise à tirer parti de son nouveau microscope holographique à illumination structurée non linéaire pour faire la lumière sur cette question. Avec une résolution spatiale de 10 femtosecondes et de 50 nanomètres, en plus de son large champ de vision, le microscope pourrait enfin éclairer les processus de séparation et d’extraction des charges sur de grandes surfaces d’échantillons.
Objectif
Solution-processed organic and hybrid materials have immense promise for low-cost photovoltaic devices. Their intrinsically heterogeneous morphology directly impacts the photophysical processes that happen over multiple timescales down to femtoseconds and which ultimately define functionality, such as carrier diffusion, charge separation and recombination. Currently, experimental techniques that can simultaneously study the nanoscale morphology and the ultrafast photophysics are limited. Ultrafast microscopes are restricted to single point or very small fields of view, lacking the large sample area coverage needed to place observations in their proper statistical context. Moreover, they are generally incompatible with super-resolution imaging, preventing the required nanoscale spatial resolution from being achieved. Recently, I introduced a widefield transient holographic microscope using off-axis holography that has shot-noise limited performance and can image large sample areas. Importantly, this approach is compatible with nonlinear structured illumination, a widefield super-resolution technique based on combining a spatially structured illumination pattern and a nonlinear sample response, with the spatial resolution being only limited by how many nonlinear terms can be acquired.
In HOLOFAST, my team and I will combine the new ultrafast holographic microscope with nonlinear structured illumination to bring unprecedented photophysical knowledge of organic photovoltaic materials, with temporal resolution down to 10 femtoseconds, spatial resolution down to 50 nm while simultaneously imaging ~100 micron areas, correlating morphology with excited state dynamics. This will enable us to finally reveal the heterogeneity of charge separation and extraction processes over large sample areas. HOLOFAST will create a photophysical and morphological database that will be valuable to understand and solve the problems that currently limit device efficiencies and lifetimes.
Champ scientifique
Mots‑clés
Programme(s)
- HORIZON.1.1 - European Research Council (ERC) Main Programme
Thème(s)
Régime de financement
HORIZON-ERC - HORIZON ERC GrantsInstitution d’accueil
00185 Roma
Italie