Investigation on the synthesis and quantum confinement effects of pure and Mn2+ added Zn(1-x)CdxS nanocrystals

Abstract

Zn(1-x)CdxS and Zn(1-x)Cd xS:Mn2+ semiconductor quantum dots (2-4 nm) have been prepared by a novel solvothermal route assisted microwave heating method. The growth parameters governing the smaller size and higher yield have been optimized. The synthesized QDs exhibit a significant blue shift as compared to their corresponding bulk counterpart in the UV-vis optical absorption spectrum. The dielectric constant value varies from 2.79 to 6.17 (at 40 °C, 1 kHz) depending upon the composition of the alloy; lower value corresponds to Zn 0.75Cd0.25S:Mn2+ and the higher value corresponds to Zn0.25Cd0.75S:Mn2+. The crystallite size to exciton bohr radius ratio being <1 indicates a strong quantum confinement effect in both CdS and ZnS QDs. The quantum confinement effect exists in the sequence of ZnS:Mn2+ < Zn (1-x)CdxS:Mn2+ (x < 0.5) < ZnS < Zn(1-x)CdxS < CdS < CdS:Mn2+. © 2011 Elsevier B.V. All rights reserved.