Nanotechnology is of great importance in various fields including biochemistry, catalysis, medical research, semiconductors etc. Synthesis of various nanoparticles through range of routes for different applications have been extensively demonstrated by researchers across the world. Size and shape of the nanoparticles is generally controlled through solution chemistry which involves selection of solvents, surfactants, ligands, reaction conditions, and many more. Semiconducting nanoparticles are also being synthesized and studied for its applications in thermoelectric, photovoltaic, sensor and many other fields.
Amine-thiol chemistry is being extensively used for fabricating thin film photovoltaics. However, in this work we will present a new approach of using this chemistry to synthesize binary, tertiary and quaternary semiconducting nanoparticles. Amine-thiol system can dissolve various metal salts and chalcogens depending on proper selection of amine and thiol pair. Taking advantage of its dissolution capability, we synthesized Copper Indium Gallium Sulfide (CIGS) and Copper Indium Sulfide (CIS) nanoparticles. These specific syntheses are carried out at high temperatures, which allows all metal precursors to react with each other forming desired phase of nanoparticles. Also, the ratio of each metal component in final CIGS or CIS nanoparticle can be varied by just selecting appropriate amount of metal precursors in the starting reaction solution. Various conditions for nanoparticle synthesis have been tested which resulted in either amine or thiol capping on the nanoparticles. Choice of these capping will give a colloidal dispersion of these nanoparticles in either polar or non-polar solvents depending on specific application. Photovoltaic devices fabricated from CIGS and CIS nanoparticles synthesized from this route will also be presented in this talk.
While proposing high temperature route to synthesize CIGS and CIS nanoparticles from amine-thiol system, we also developed a novel room temperature synthesis route for lead chalcogenide nanoparticles. Lead chalcogenide nanoparticles are being used in various applications including quantum dot solar cell (PbS, PbSe) and thermoelectric systems (PbSe, PbTe) since past many years. In our work, we have demonstrated quantum confinement of self-assembled PbS nanoparticles synthesized from this amine-thiol room temperature route. Our work also shows size control for both PbS and PbTe nanoparticles and their self-assembled microstructures. Thermoelectric properties measured for PbSe nanoparticles synthesized through this route has also shown comparable results with those reported in the literature.
In conclusion, we present a novel route to synthesize and tailor an array of semiconducting nanoparticles using amine-thiol chemistry at different temperatures for various applications.