Aqueous synthesis and characterization of CdS, CdS:Zn(2+) and CdS:Cu(2+) quantum dots

CdS quantum dots of different sizes approximately 3-5nm were prepared using aqueous solutions of CdSO(4) and Na(2)S(2)O(3) at 303K with thioglycerol as stabilizing agent and catalyst. The broad X-ray diffraction pattern and SAED pattern with bright circular spots and clear lattice fringes in the high-resolution TEM image indicate cubic phase of the nanocrystals. Band gap changes from the bulk value of 2.4 to 3.16eV in the nanoparticles indicating quantum size effect. The photoluminescence (PL) spectrum is blue-shifted to 528nm. The PL emission band is blue/red-shifted on doping with Zn(2+)/Cu(2+). In the case of Cu(2+), the PL intensity is found to be maximum at 10wt% doping and almost completely quenched at 15wt% doping. On doping with Zn(2+), the intensity and blue-shift of PL are found to be maximum at 2 and 6wt% doping, respectively.