Enhanced Thermoelectric Performance in Ga-Doped In2O3 through Synergistic Optimization of Carrier Concentration and Lattice Thermal Conductivity

In this paper, gallium-doped indium oxide (In2O3) compounds with different doping amounts were fabricated through the hydrothermal method and the Spark Plasma Sintering process. X-ray diffraction showed that Ga was efficiently doped into the In2O3 lattice. The electrical conductivity is significantly improved by Ga doping, which is due to the reduced potential barrier of the carriers for the transition to the conduction band. The carrier concentration of Ga-doped In2O3 reaches 1.11 × 1020 cm–3, which is 12 times that of pristine In2O3, and the electrical conductivity (6.79 × 104 S m–1) is 5 times that of pristine In2O3. Furthermore, the lattice distortion in the doped sample acts as strong phonon scattering centers, which effectively reduce the mean free path of the phonons, resulting in a significant decrease in the lattice thermal conductivity. Finally, at 873 K, the zT value of In1.88Ga0.12O3 reaches 0.22, which shows a 100% increase compared with that of the pure In2O3 sample. Our results show that the control of metal doping and microstructure can achieve synergistic optimization of the electrical properties and thermal conductivity of In2O3, providing a reference for other thermoelectric materials.