Enhanced Thermoelectric Performance of In2O3 via Potassium Doping: Decoupling Electrical and Thermal Transport

Abstract

To tackle the low thermoelectric figure-of-merit (ZT) of In₂O₃-based n-type oxide thermoelectrics arising from high thermal conductivity, we perform a systematic investigation on K-doped In₂O₃. Doping with large-radius K⁺ achieves coordinated regulation of electrical and thermal transport behaviors. Characterizations confirm that low-concentration K is fully soluble in the In₂O₃ lattice and triggers lattice expansion and distortion. After K incorporation, the carrier concentration increases from ~ 8.6 × 10¹⁷ cm⁻³ to ~ 1.33 × 10¹⁹ cm⁻³, along with enhanced electrical conductivity. The elevated density of states around the Fermi level restrains the reduction of the Seebeck coefficient and optimizes the power factor. The introduced mass and stress fluctuations lower the Young’s modulus and strengthen phonon scattering, leading to reduced lattice thermal conductivity. By separately optimizing electrical conduction and thermal conduction, the ZT value and high-temperature thermoelectric performance of the samples are improved. This work provides a practical doping route for the preparation of high-performance, low-cost and environmentally friendly n-type oxide thermoelectric materials.