Improved thermoelectric efficiency in p-type ZnSb through Zn deficiency

We herein report a feasible approach to improve the thermoelectric performance of p-type ZnSb compound by Zn content regulation. It is found that Zn vacancies formed by Zn deficiency not only efficiently enhance the electrical conductivity due to the improved hole concentration but also markedly lower the lattice thermal conductivity on account of the reinforced point defect scattering of phonons. The ZnSb compound with a nominal 3 mol.% Zn deficiency shows a maximum thermoelectric figure of merit ZT of ~ 0.8 at 700 K which is a ~ 60% improvement over the pristine sample. The strategies of further enhancing the performance of ZnSb -based material have been discussed.