Self-assembled organic-inorganic hybrid nanocomposite of a perylenetetracarboxylic diimide derivative and CdS

A perylenetetracarboxylic diimide derivative, N-n-hexyl-N′-(2- hydroxyethyl)-1,7-di(4′-t-butyl)phenoxy-perylene-3,4:9,10-tetracarboxylic diimide (HO-PDI), was synthesized and self-assembled as a monolayer thin solid film on the modified surface of a quartz substrate by an ester bond between -OH groups of HO-PDI molecules and -COOH groups of p-phthalic acid grafted onto the hydrophilic pretreated SiO₂ surface. An analysis of the spectral change revealed the J-aggregate nature of HO-PDI molecules in the obtained thin solid film. With this thin solid film of HO-PDI as a template, CdS nanoparticles were deposited on it in situ, which were further characterized by electronic absorption, fluorescence, and energy-dispersive X-ray spectroscopy (EDS). The morphology of CdS nanoparticles is disklike, and the diameter is ca. 140 nm as determined by atomic force microscopy (AFM). Furthermore, electron transfer between the organic layer and CdS nanoparticles was deduced through fluorescence quenching and theoretical analysis.