Effect of polar solvents on the growth, morphology and thermoelectric properties of Bi2Te3 nano particles

Abstract

Morphological tuning of nanostructures aims to enhance thermoelectric figure of merit (ZT) through a rise in the density of states near the fermi level and spatial confinement of acoustic phonons leading to reduction in thermal conductivity. In this work, we prepared Bi 2 Te 3 nanostructures with diverse morphology, by a facile and scalable single-pot hydro/solvothermal synthesis, and investigated the effect of different polar solvents on the morphology of the synthesized nanostructures. Single-phase and highly crystalline Bi 2 Te 3 with diverse morphologies including nanoparticles, nanosheets, nano and micro flakes, nanotubes and nanoflowers were grown in different polar solvent media. The Materials were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and selected area diffraction pattern (SAED). A possible growth mechanism for Bi 2 Te 3 nanostructures is proposed by considering the physical and chemical properties of the polar solvents, with special focus on their dielectric properties. The thermoelectric properties of the hot pressed samples were investigated in the temperature range of 300–480 K. The fermi level is found to be shifted by morphological tuning of nanostructures. The carrier concentration and transport parameters are found to be greatly influenced by the morphology of consolidated particles. A peak figure of merit of 0.46 was obtained for the in-situ fullerite coated sample synthesized with ethylene glycol as medium (BTEGEDTA) at a temperature of 474 K. • Bi 2 Te 3 nanoparticles with diverse morphology were grown in different solvents as media and the thermoelectric properties are found to be varied. • In-situ fullerite coated B i2 T e3 was obtained by using ethylene glycol as medium • A possible growth mechanism is suggested by considering the chemical and physical properties of the medium. • The fermi level is found to be shifted with morphological tuning.