Plasmon-Induced Fluorescence Enhancement in Aminoporphyrin Thin Film Coupled with Gold Nanocubes Array

A hybrid plasmonic-molecular architectures were prepared by depositing a self-assembled gold nanocube (AuNC) monolayer onto a pre-formed aminoporphyrin (NH₂TPPH₂) thin film. Fluorescence spectroscopy (absorption and emission spectra, emission lifetimes) was employed to characterize the system’s photophysical properties before and after the deposition of the Au nanostructure. The fluorophore, characterized by a multi-peaked absorption in the visible range, and the nanostructure, with its broad extinction spectrum extending from visible to NIR, were appropriately chosen to achieve a large overlap of the absorption/emission bands with the plasmon resonance band, promoting a strong fluorophore-nanostructure coupling. This configuration enabled a systematic investigation of NH₂TPPH₂ photophysical response under controlled plasmonic excitation, allowing for the first time the study of the correlation between excitation wavelengths and plasmon band intensity in a single PEF platform. Furthermore, a first preliminary measurement of PEF performance of an AuNC monolayer-based platform were reported.