Meet the jury: lecture by Rachith S. N. Kumar

Interfacial Control of Hot Carrier Cooling in Plasmonically Enhanced Halide Perovskites

In semiconductors, photoexcited carriers lose excess energy to the lattice within a few picoseconds, posing challenges for capturing hot carriers in photovoltaics and photocatalysis. Lead halide perovskites can retain energy at high carrier densities, where a hot-phonon bottleneck slows thermalisation. Plasmonic metal nanostructures can assist this process by transferring energy to carriers, but may also lead to energy loss.

This lecture will show that adding a nanometer-scale spacer between Ag-Au nanoparticles and a MAPbBr3 film modulates these interfacial processes and influences plasmon-derived energy. Using transient absorption spectroscopy to measure carrier temperature (Te), we find that direct metal contact leads to the fastest cooling due to energy back-transfer. Semiconducting TiO2 enhances hot-electron extraction and cooling (5-9 ps), while insulating Al2O3 slows down cooling (approximately 16 ps). The notable effects are observed only under 2.48 eV excitation, confirming their plasmonic nature. Our results suggest that interfacial energy-transfer pathways largely govern hot-carrier cooling in these structures

Practical information

• Monday August 24th, 3.30 - 4.30 PM
• Location: lecture hall H3, Building D, Campus Diepenbeek
• Online link later available