Preparation and luminescence properties of spin-coated PMMA films containing Si nanocrystallites

We report on the synthesis of Si nanocrystallites by pulsed laser ablation in toluene followed by the preparation of composite films with PMMA and their luminescence studies. Transmission electron microscopy images show that the sizes of silicon nanocrystallites vary from about 4   nm down to below 1   nm. The composite films exhibit strong emissions with their spectral peaks continuously moving from 387 to 506   nm when the excitation wavelength varies from 300 to 440   nm, in accordance with the quantum confinement effect . Their time-resolved photoluminescence spectra reveal a multi-exponential decay, implying that the light emission may be also related to some surface states .