Design and fabrication of highly efficient thermoelectric renewable energy harvesting chalcogenide materials using advanced laser techniques supported by DFT

The development of clean and sustainable energy sources has been one of the major focal point and hot area of research in recent times. This is due to the incessant inimical effects of fossil fuels (such as pollution and global warming) to the environment. Thermoelectric technology is an emerging field that can be used to harness industrially generated waste-heat or by sun (solar energy) in form of useful electrical energy through purely renewable means via the principle of Seebeck effect. On the other hand, it can also be used for solid-state refrigeration applications through the Peltier effect. Chalcogenide-based materials (compounds constituting Se and Te species) have proven to be potential thermoelectric candidates with a high figure of merit due to the possibility of manipulating their phonon transport behaviour to reduce the lattice contribution to the over all thermal conductivity. Excellent thermoelectric materials must have a figure of merit ( ) greater than unity for large-scale applications. The interdependence of the governing thermoelectric parameters makes it extremely laborious to achieve such a milestone. This is predominantly due to the trade-off existing between the relevant variables, for instance, an increase in electrical conductivity would enhance the electronic contribution to the total thermal conductivity and but reduce the Seebeck coefficient as well. Our proposed research in this field will focus on materials design through nano-structuring, defects incorporation, pressure inducement, band engineering, and phonons scattering to mention a few here. In the present work, several of these chalcogenides (-Cu2 xSe, TlSe and SnTe) and their composites will be grown using different laser-based advanced nanomaterial fabrication techniques. Our choice of nanomaterials is to enable us to control the grain boundaries and engineer the phonon transport, thus, lowering the total thermal conductivity and in-turn improve the figure of merit. The value of ZT can be enhanced either by increasing the electrical conductivity or by lowering the thermal conductivity. The bandgap study will be carried out to understand the electrical conduction of the material. The Raman Scattering study will be carried out on the samples to understand the effect of nanostructure doping on phonon conduction. Mixing secondary nanocomposites (e.g. carbon nanotubes) with chalcogenide-based compounds will also be another major objective of this research project. The proposed nanostructures will be instrumental to create grain boundaries in the thermoelectric materials that may scatter off the phonons (lower the thermal conductivity) without reducing electrical conductivity. In addition, First-principles DFT ab-initio calculations will be conducted to understand the stability, electronic and structural properties of these materials. The DFT study will also be applied to investigate the response of these materials to electrons and holes doping using rigid band approximations. The effect of hydrostatic pressure on the thermoelectric properties will also be investigated