Energy Conversion Efficiency of a Piezo-Thermoelectric Material

This work presents a set of one-dimensional piezo-thermoelectricity equations for semiconductors exhibiting both piezoelectric and thermoelectric effects. Diffusion current due to the carrier concentration gradient is considered in the piezo-thermoelectricity theory. The coupled equations satisfied by the temperature, carrier concentration, and mechanical displacement are derived. The theory is subsequently applied to a thin film of a zinc oxide (ZnO) piezo-thermoelectric material subjected to a steady state temperature gradient in the thickness direction and fixed-end boundary conditions. The numerical results show that the energy conversion efficiency may be significantly increased by the coupling between the thermoelectric and piezoelectric effects.