Luminescent CdS Nanoparticles Embedded in Polyethylene Glycol (PEG 300) Matrix Thin Film

A simple method for synthesis of well dispersed cadmium sulphide (CdS) nanoparticles embedded in a polyethylene glycol matrix (PEG 300) in thin film form is presented. The molar ratio of PEG and CdS was varied within the range 70 : 30 to as high as 50 : 50. Films with controllable sizes (r ∼ 3 –8 nm) of nanocrystals could be obtained by adjusting post-deposition annealing temperature (T) and time (t). The obtained films showed systematic variation in optical properties with decreasing crystal size due to quantum confinement. Transmission electron micrographs (TEM) indicated well resolved nanoparticles for films annealed at lower temperature (T = 373 K) and time (t < 45 min). Photoluminescence (PL) studies indicated blue shift with decreasing particle size. The films did not degrade with aging in a humid atmosphere (relative humidity 40%) for several weeks.