Study on the mechanism of influence of impurity levels introduced by doping high-valence element on the properties of zinc oxide thermoelectric materials

Herein, the design, preparation, and characterization of zinc oxide thermoelectric materials and the mechanism of energy conversion efficiency improvement were systematically and deeply explored. Through the detailed analysis of a series of experimental data and the construction of theoretical models, the following mechanism is revealed. By introducing W element to dope at Zn sites of ZnO with significantly improved thermoelectric properties, it can not only increase the electron state density near the Fermi level, increase the carrier concentration, effectively improve the tradeoff relationship between the material's conductivity and Seebeck coefficient, improve the power factor, but also strengthen phonon scattering and reduce Young’s modulus. Thus, the lattice thermal conductivity is significantly reduced, and the overall thermoelectric conversion efficiency is further improved. The experimental results show that the ZT value with the highest value reaching ~ 0.379 for W-doped ZnO-based thermoelectric material is about ~ 3.9 times higher than that of traditional materials at a specific operating temperature, showing great potential for performance optimization.