Photo‐ and Electro‐Luminescence of Mn‐Doped CdS Nanocrystals

Abstract

Nanocrystals of CdS∶Mn were prepared by chemical technique. The samples were characterized by scanning electron microscope (SEM), X‐ray diffraction (XRD) and absorption spectra. Photoluminescence (PL) of the nanocrystals was studied for various concentration of Mn. Electroluminescence (EL) of the nanocrystals was obtained by placing them between SnO2 coated conducting glass plate and aluminum foil as electrodes. SEM gives the size of the particles of the order of 40 nm and crystallite size estimated by XRD is of the order of 20 nm. The absorption spectra of nanocrystals are blue shifted and shows steps, confirming the discretization of energy levels due to quantum confinement. PL spectra give two major peaks; intensity of first peak increases and second peak shifts towards blue by increasing Mn concentration. EL studies show nonlinear increase in brightness with increasing voltage. It is seen that EL brightness tends to saturation for high voltages, and saturation EL brightness is higher for lower frequencies.