Effect of Indium doping on structure and thermoelectric properties of bismuth telluride

Owing to their high near-room-temperature conversion efficiency, bismuth telluride (Bi2Te3) and its alloys are prominent thermoelectric materials. While indium (In) is a typical dopant in thermoelectric materials, the hydrothermal synthesis of In-doped Bi2Te3 has not yet been reported to the best of our knowledge. Herein, we report the synthesis of In-doped Bi2-xInxTe3 (x = 0, 0.1, 0.2, 0.3) by a hydrothermal method combined with hot press sintering. The incorporation of In enhanced the Seebeck coefficient and suppressed thermal conductivity, primarily due to the reduced carrier concentrations and intensified phonon scattering. Consequently, a maximum zT value of 0.21 was obtained at 350 K for Bi1.9In0.1Te3 sample, approximately 162.5% improvement over the undoped counterpart, demonstrating the effectiveness of In doping in improving the thermoelectric properties of Bi2Te3.