Effect of rGO on the Microstructure and Thermoelectric Properties of SnSe2 for Green Energy Harvesting

Abstract

Thermoelectric (TE), is a solid-state technology to convert waste heat into useful energy based on Seebeck effect, which can make significant contributions to solve the global energy crisis by providing a sustainable energy solution. SnSe, being a lead-free, environmentally friendly and cheap semiconductor, has been an attractive choice for TE community. Here, the focus is on its layered structure of the same chalcogenide family, SnSe2, an n-type semiconductor. In this research, we analyzed the potential of SnSe2-rGO composite as a TE material and the effect of rGO concentration on its TE properties. SnSe2-rGO composites were synthesized via solvothermal route followed by sintering at 550°C in the presence of Argon. In-situ doping of rGO within SnSe2 matrix was successfully achieved. The resultant composite showed a significant improvement in electrical conductivity which displayed a peak value of 2479 S/m (Pure SnSe2=750 S/m) at 300K. This enhancement is due to the electronic structure of SnSe2 and the presence of rGO conductive sheets, which improved the carrier concentration. Introduction of rGO also resulted in controlling the lattice thermal conductivity due to phonon scattering. The investigation showed that increasing the rGO concentration had a positive impact on the overall ZT of the samples, achieving a peak ZT of 0.18 for 4-SG sample at 750K. This increase can be related to the increasing electrical conductivity due to rGO addition and the reduction in band gap.