Significant improvement in the thermoelectric performance of Sb-incorporated chalcopyrite compounds Cu18Ga25SbxTe50−x (x = 0–3.125) through the coordination of energy band and crystal structures
作者： Junhao Zhu , Yong Luo , Gemei Cai , Xianglian Liu , Zhengliang Du
DOI: 10.1039/C7TA08568K
关键词: Ternary operation 、 Electronic band structure 、 Fermi level 、 Crystal structure 、 Semiconductor 、 Chalcopyrite 、 Band gap 、 Crystallography 、 Thermoelectric effect 、 Materials science
摘要: A newly developed chalcopyrite semiconductor Cu18Ga25Te50 (Cu/Ga = 0.72) has an inherent deficiency in Cu. Therefore, it is taken as a thermoelectric candidate due to high vacancy rate of copper. In this work, we have observed that after Sb substitution for Te Cu18Ga25SbxTe50−x, the active Sb-5p orbital hybridizes with those Cu-4s and Te-5p valence band, which makes Fermi level (Ef) unpin move toward inner side band content increases. The alteration structure, determining factor, causes Hall carrier concentration (nH) rise by more than one order magnitude compared pristine Cu18Ga25Te50, thereby significantly increasing power factor (PF). Combined relatively low thermal conductivity, caused increased lattice disorder general diminution crystal structure distortion x value increases, attained best TE performance, where ZT reaches highest 1.2 Sb-incorporated Cu18Ga25SbxTe50−x (x 2.5) at 854 K. This result suggests coordination energy structures good approach achieving performance via appropriate ternary semiconductors.
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