Electronic and optical properties of semiconducting nanoparticles

It is well known that physical and chemical properties of various semiconductors can be tuned by controlling its size in the quantum confinement regime of few nanometers. It has immense application possibility in terms of electronic, optical, as well as opto-electronic devices, since it is conceivable now to prepare materials with tailor-made properties. At the simplest level, this tunability can be thought of as the changes in the electronic level energies with the spatial extension of the confining potential in the classic particle-in-a-box problem. While this does provide an overall understanding of the tuning of various properties of nanomaterials, most notably the tuning of the bandgap and also changes in the quantum efficiencies for light emission, it is too simplistic in practical terms. Therefore, many interesting basic science issues are involved in these activities.

We have synthesised different semiconducting nanoparticles, such as CdS, ZnS, PbS, CdSe and ZnO, as well as Mn doped semiconducting nanoparticles using various chemical routes to yield stable nanoparticles with narrow size distributions. I shall discuss the synthesis and characterization of such stable nanoparticles in our group as well as discuss the electronic and optical properties both in terms of experimental investigations as well as theoretical studies to illustrate the tuning of bandgap and other properties as a function of size of the nanoparticles.