2,4,5-triphenylimidazole nanowires with fluorescence narrowing spectra prepared through the adsorbent-assisted physical vapor deposition method

The single crystalline nanowires have been fabricated from a small organic functional molecule, 2,4,5-triphenylimidazole (TPI), through an adsorbent-assisted physical vapor deposition (PVD) method. The introduction of the absorbents can significantly improve the dimensional uniformity of the as-prepared TPI nanowires. The TPI nanowires displayed interesting size-dependent optical properties, that is, the absorption spectra of the wires exhibit an obvious blue shift with the decrease of diameter, and simultaneously, the vibrational fine structures of the emission spectra emerge and become more pronounced with the diameter decreasing from 500 to 40 nm even at room temperature, which are usually observed only under cryogenic conditions. The emergence and enhancement of the vibrational structures are contributed to the increase of the long-range order and the degree of orientation with the decrease of diameter. The strategy described here should give a useful enlightenment for the fabrication of wirelike nanostructures from small organic molecules.