Waste heat energy harvesting by using praseodymium, nickel codoped zinc oxide thermoelectric materials

ZnO is a semiconductor with immense potential to use in different technological applications including in non-conventional energy generation such as thermoelectric generators and sensors. Herein, we investigated the thermoelectric properties of praseodymium and nickel codoped ZnO microcrystals. Structural studies and the optical band gap reduction confirmed the inclusion of the dopants into the host lattice. The codoping of praseodymium and nickel causes an increment in carrier density, which enhances the electrical conductivity of the materials. The energy filtering effect leads to the highest Seebeck coefficient of - 716 mu V K-1. Simultaneous increments in electrical conductivity and the Seebeck coefficient enhanced the power factor of the doped materials. The doping of praseodymium ions with nickel ions induces more lattice distortions, which resulted in the drastic reduction of thermal conductivity from 17.8 W/mK to 3.7 W/mK. Enhancement of power factor with a significant reduction in thermal conductivity leads to a three-fold improvement in the thermoelectric figure of merit of ZnO materials.