Bismuth-Doped Indium Oxide as a Promising Thermoelectric Material

Bismuth (Bi)-doped indium oxide (In2O3) has emerged as a promising thermoelectric material due to its tunable electrical and thermal properties. This study investigates the effects of Bi-doping on the thermoelectric performance of In2O3, focusing on its electrical conductivity, band structure, carrier concentration, mobility, Seebeck coefficient, power factor, thermal conductivity, and overall thermoelectric figure of merit (ZT). The incorporation of Bi into the In2O3 lattice significantly enhances the material’s electrical conductivity, attributed to the increased carrier concentration resulting from Bi acting as an effective dopant. However, this doping also leads to a broadening of the bandgap, which influences the electronic transport properties. The Seebeck coefficient (absolute value) is observed to decrease with Bi-doping, a consequence of the elevated carrier concentration. Despite this reduction, the overall power factor improves due to the substantial increase in electrical conductivity. Furthermore, Bi-doping effectively reduces both the total thermal conductivity and the lattice thermal conductivity of In2O3. This reduction is primarily due to enhanced phonon scattering caused by the introduction of Bi atoms, which disrupt the lattice periodicity and introduce point defects. The combined improvement in electrical conductivity and reduction in thermal conductivity results in a significant enhancement of the thermoelectric figure of merit (ZT) with highest ZT value increased from 0.055 to 0.402 at 973 K. The optimized Bi-doped In2O3 samples demonstrate a ZT value that surpasses that of undoped In2O3, highlighting the potential of Bi-doping for advancing thermoelectric applications. This work provides a comprehensive understanding of the underlying mechanisms governing the thermoelectric properties of Bi-doped In2O3 and offers valuable insights into the design of high-performance thermoelectric materials for energy conversion technologies.