Synthesis and Photoluminescence Studies on Nanocrystalline Content Cds Film

The photoluminescence is a process in which the material is excited by short wavelength electromagnetic wave and de-excitation causes emission of light. In many cases, photo-luminescence is obtained by band-to-band transition and photoluminescence peaks at the same photon energy as the absorption edge. Hence the photon energy corresponding to photoluminescence peak can be considered to be the effective band gap of material. In nanocrystals, as the size of the crystal is reduced, photoluminescence peaks has been found to shift towards shorter wavelength. The size of nanoparticles can be estimated using theoretical models relating the increase in band gap with the radius of particle. Cds nanoparticles of different sizes have been prepared and their size has been estimated by shift in photoluminescence peak using effective mass approximation model and hyper-bolic band model. Films of Cds nanoparticles were prepared by the chemical bath deposition for various time duration and their photoluminescence spectra have been studied. Photoluminescence peak shifts towards longer wavelength indicating increase in energy band gap as the deposition time is increased. Estimation of the particle size from the shift in photoluminescence peak indicates that larger particle is formed with longer deposition time.