Organic capping-Effect and mechanism in Mn-doped CdS nanocomposites

Driven with an objective of confining the growth of nanoparticles, polyvinyl pyrrolidone (PVP) was used as a capping agent over Mn+2-doped US nanoparticles. The mechanism is studied and results are discussed. An improvement in the doping efficiency and improvement in reproducibility of the nanoparticles as compared to the common co-precipitation method is observed which can be endorsed to the introduction of PVP as coordination of PVP molecular orbitals with metallic orbitals attribute to the surface passivation of the CdS nanoparticles. PVP helps in stabilizing the nanoparticles, increases the doping efficiency and leads to enhancement in optoelectronic properties. A change in band gap is noticed as there is blue shift in wavelength compared to bulk due to confinement of particle size. The obtained nanoparticles are characterized by X-ray diffraction, transmission electron microscopy, ultraviolet-visible and photoluminescence spectroscopy. (C) 2009 Elsevier B.V. All rights reserved.