Recent investigations of the high thermoelectric figure-of-merit ZT of 2.6 for SnSe crystalline compound demonstrated the state-of-the-art highest thermoelectric performance in spite of the high ZT value in a narrow temperature range and along a specified crystallographic direction. We investigated the thermoelectric properties of polycrystalline Sn1-x InxSe (x = 0.0, 0.01, 0.05, and 0.1) compounds and the optical properties of single crystalline compounds. Sn1-x InxSe exhibits increased electrical resistivity, an increase in the Seebeck coefficient and band gap energies, and a significant decrease in the Hall mobility with an increase in the In-doping concentration, whereas the Hall carrier density does not changed significantly. These abnormal results and the decrease in the lattice volume with an increase in the In-doping concentration strongly imply the existence of band renormalization by In 4d- and Se 4p-orbital hybridization. We argue that the significant flat bands by band renormalization induce significantly decreased Hall mobility and increases in the electrical resistivity and Seebeck coefficient, resulting in the deterioration of the thermoelectric properties.
Bibliographical noteFunding Information:
This research was supported by Nano-Material Technology Development Program ( 2011-0030147 ) through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology and Energy Efficiency & Resources program of the Korea Institute of Energy Technology Evaluation and Planning(KETEP) grant funded by the Korea government Ministry of Knowledge Economy (No. 20112010100100 ), and LG Electronics .
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- Band renormalization