Publications

Solar energy : Laveena D Souza and Quantum Dots : Chandan Bhardwaj

Amongst the various options of renewable sources, solar energy acts as a prominent source of clean energy. The economical and abundantly available energy source the sun light, moreso in India, has been utilized by fluorescent/nanocrystals which are synthesized and characterized in our laboratory via thin film depositions. Semiconductor QDs open a new way to utilize hot electrons via impact ionization. Semiconductor QDs are more promising alternative and posses a larger extinction coefficient as compared to conventional dyes in Dye sensitized Solar cells.

Different techniques of fabrication like CBD, molecular linkers, drop cast technique and electrophoresis are explored for linking molecules to thin films.

Non availability of the required QD sizes and the high cost involved instigated the research of synthesizing quantum dots. Colloidal approaches provide quantum dots of excellent quality due to the control in their size, shape, structure and composition of the material, and hence were directly prepared and used for the said applications using precise growth techniques, involving accurate annealing temperatures. Choice of shell and coating are explored, as the shell stabilises the nanocrystal and to some extent alters the photophysical properties, whilst the coating confers properties to the QD which allow its incorporation for a desired application. An attempt to reduce the effect of major toxic components namely phosphine ligands and unsaturated solvents as being used in conventional nanocrystal synthesis, has been made with a new binary ligand, and a reusable solvent n-octadecane for a smokeless and clean synthesis procedure. The optimized effects of the two ligands oleic acid and octadecyl amine on the nucleation rate and growth of CdSe nanocrystals are reported.

QDs, particularly long fluorescence lifetime and photostability allows multiplexed imaging in which QDs could act as ideal probes. . The optoelectronic properties of nanocrystals are fundamentally understood and shall further be applied. The prepared fluorescent nanocrystals are envisaged to be used as bio-markers to identify the food and waterborne pathogens. Methods in adapting QDs for in vitro diagnostics mainly in immunoassays for rapid detection of food and water borne enteric pathogens are the future focus areas.

Our interests include,

• Photochemistry and water purification (Oxidation / reduction of pollutants / toxic metal ions, pathogen inactivation)
• Membrane Science 
• Nanoparticles and mesostructure materials
• Bioenergy