Preparation of Perylenediimide Nanoparticle Colloids by Laser Ablation in Water and Their Optical Properties

Fluorescent nanoparticles of N,N '-bis(2,5-di-tert-butylphenyl)-3,4,9,10-perylenedicarboximide (DBPI) were fabricated by laser ablation of its microcrystals dispersed in pure water, and their optical extinction and fluorescence spectra were investigated. Colloidal nanoparticles withmean sizes of 30 to 80 nm were prepared without molecular decomposition by tuning the fluence of the irradiating laser. Spectral simulation based on Mie theory explains the difference in the absorption spectra of the nanoparticles and a DBPI vapor-deposited film. The fluorescence of the nanoparticle colloids showed a monomer-like emission band with a vibrational structure, while the initial microcrystals exhibited a broad excimer band. These results indicate that the DBPI nanoparticles have crystal morphologies different from those of microcrystals.