In this work, brightly luminescent silicon nanocrystals films coated with spin-on glass (SOG) are presented. The photoluminescent (PL) emission observed agree mainly with the quantum confinement effect, but after annealing in different environments (N2, O2 and N2 + H2) and temperatures, the PL changes and a significant shift toward different wavelengths is observed. The shift shows that not only electron–hole recombination inside the silicon nanocrystals (Si nC) takes place (quantum confinement effect), but also emission by defects located at the Si nC/SiO2 interface is observed. Based on the results of PL and Fourier Transform Infrared (FTIR), we show that the PL emission from Si nC coated with SOG is due to different kind of defects localized at the Si nC/SiO2 interface. Si=O defect bonds are formed during the different annealing environments. The results help to figure out how the different emission mechanisms contribute in the complete PL response.