文摘
The functionalization of wide bandgap semiconductors and insulators with self-assembled layers of polycyclic aromatic hydrocarbons (PAHs) has gained major attention due to various potential applications such as sensors, in molecular electronics, or in solar cells and organic light-emitting diodes. Their fluorescence properties depend among others on the spatial arrangement and aggregation of the molecules on the surface. In the present study, silane linkers of different length and conjugation were employed to functionalize silicon carbide and silicate surfaces with two PAHs. High-resolution X-ray photoemission spectroscopy (XPS) ascertained the degree of functionalization, supported by attenuated total reflection Fourier transform infrared spectroscopy and contact angle measurements. The homogeneity of the functionalized layers was evaluated by fluorescence microscopy. Using ultraviolet excitation, both a blue and a broad band fluorescence emission extending from 500 nm to beyond 600 nm were observed. Lifetime measurements revealed generally longer decays for the longer aliphatic AUDTES linker in comparison with the shorter aliphatic and aromatic spacers. Even though silicon carbide favors aggregation and shows a higher functionalization efficacy than the silicate substrates, the lifetimes of the fluorophores are not extensively influenced by the nature of the substrate but rather by the spatial arrangement of the luminescent species.
