Tuning the Luminescence of CdS Quantum Dots by a Simple Method

In this report, we present a facile approach for the synthesis of luminescent CdS and CdS:Mn+2 nanocrystals by reaction of CdSO4 and Na2S2O3 in the presence of thioglycerol (C3H8O2S) as capping agent. The influence of various experimental variables including, pH values and percentage of dopant, on the growth rate and optical properties of the obtained CdS nanocrystals has been systematically investigated. Experimental results show that by lapsing time and increasing particles size, red shift has occurred in the absorption edge and peak of luminescence. Luminescence of CdS nanoparticles covers 480-650nm of visible range. This luminescence arises from trap states and reaches to its maximum in pH=6 after 5 days. Doping of CdS with Mn+2 is found to enhance the photoluminescence (PL) intensity. PL Peak in CdS:Mn+2 sample has shifted towards 580nmdue to transition in Mn+2 ions.