Enhanced thermoelectric properties of ZnO: C doping and band gap tuning

ZnO is a promising high-temperature thermoelectric material because of its non-toxicity and low-cost. However, the wide band gap and low electrical conductivity lead to inferior thermoelectric properties. Herein, C-doping in ZnO bulk was achieved by the pyrolysis of hydrothermal surfactant TEA through a facile and speedy SPS technique. DFT calculation and experimental results show that C was incorporated into the O-site in ZnO, which reduces band gap and increases carrier concentration, thereby improving electrical conductivity and power factor. Meanwhile, the additional point defects introduced by the substitution of C/O atoms strengthen phonon scattering and decrease thermal conductivity. Benefiting from C-doping via not only tuning the electrical transport properties but also reducing the thermal conductivity, a peak ZT value of 0.024 at 773 K was achieved for Zn(O,C) bulk. It indicates that C-doping in ZnO is an effective and convenient strategy to improve thermoelectric performance.

Automated summary

C-doping in ZnO was achieved through a facile and speedy SPS technique, improving electrical conductivity and power factor by reducing band gap and increasing carrier concentration. Meanwhile, introduced point defects strengthened phonon scattering and decreased thermal conductivity, leading to a peak ZT value of 0.024 at 773 K for Zn(O,C) bulk. This demonstrates that C-doping in ZnO is an effective and convenient strategy to enhance thermoelectric performance.