Realizing High Thermoelectric Performance in the ZnTe-Alloyed CuGaTe2 through Band Engineering

Recent years have witnessed the chalcopyrite compound CuGaTe2 receiving widespread attention as a promising thermoelectric material. In the work, we calculated the band structure of Zn substitution at the Ga site and found that the Zn element can effectively adjust the band degeneracy and tetragonal distortion parameters of CuGaTe2. By doping CuGaTe2 with different contents of ZnTe, it is discovered that the Zn-Ga(-) point defects formed by CuGaTe2-ZnTe concrete solutions can increase the carrier concentration of CuGaTe2 material significantly. Meanwhile, it strongly scatters the short-wavelength phonons and reduces the lattice thermal conductivity. Therefore, the electrical and thermal properties of the material are effectively improved. The ZT value of (CuGaTe2)(0.9975)(2ZnTe)(0.0025) reaches 0.74 at 810 K, which is nearly 28% higher than the 0.58 of the undoped CuGaTe2 sample.