Nanocrystal-to-Ligand Interfacial Thermal Transport: Plasmonic Indium Tin Oxide to Perylene Diimide Adsorbates

The generation and dissipation of heat in nanocrystals upon optical excitation is a process that may either limit or enhance their performance in certain applications. Using transient absorption spectroscopy, we tracked the flow of heat from plasmonic tin-doped indium oxide (ITO) nanocrystals to surface-adsorbed perylenediimide (PDI) molecules upon excitation of the ITO near-infrared plasmon resonance. We rationalize that the derivative line shapes observed in the transient absorption bleach features are the result of thermal transfer from the ITO core to surface ligands based on temperature-dependent static absorption studies of the PDI molecules adsorbed on plasmonic ITO. Through a series of pump power-dependent measurements, we demonstrate that the PDI heating time is largely fluence-independent at the powers measured, while the overall recovery time increases. Elucidating thermal transfer rates at the nanocrystal and organic ligand interface is key for applications such as plasmon-mediated photocatalysis, where heating may obstruct hot carrier transfer processes.