Crystal Structure, Electronic Transport, and Improved Thermoelectric Properties of Doped InTe

This paper focuses on the crystal structure, electronic transport, and improved thermoelectric properties of InTe by combining experimental and theoretical methods. P-type InTe doped with Bi, Ag, Mn, Sn, or Sb is experimentally studied, resulting in improved zT values. The enhanced thermoelectric performance is mainly induced by reduced thermal conductivity. The highest performance is achieved in In_0.99Sn_0.01Te, which exhibits an enhanced zT by a factor of approximately 1.6 compared with the pristine sample. The crystal structure is investigated in detail by using synchrotron powder X-ray diffraction. The electronic structure of InTe is calculated using the TB-mBJ method within density functional theory, and a band gap of 0.16 eV is obtained. Based on the electronic structures, Boltzmann transport theory is applied to calculate the electrical transport properties, and their excellent agreement with the experimental data verifies the effectiveness of the rigid band approximation. Importantly, electrical transport properties are predicted to be favorable as the n-type, which is attributed to a high valley degeneracy of the conduction band minimum. We anticipate an improved power factor and zT in n-type InTe if it can be n-doped. This work provides systematic insight into the crystal structure and electronic transport of InTe, which is important for the further optimization of InTe thermoelectrics.