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In this work the chalcopyrite CuIn3Se5−xTex (x = 0~0.5) with space group through isoelectronic substitution of Te for Se have been prepared, and the crystal structure dilation has been observed with increasing Te content. This substitution allows the anion position displacement ∆u = 0.25-u to be zero at x ≈ 0.15. However, the material at x = 0.1 (∆u = 0.15 × 10−3), which is the critical Te content, presents the best thermoelectric (TE) performance with dimensionless figure of merit ZT = 0.4 at 930 K. As x value increases from 0.1, the quality factor B, which informs about how large a ZT can be expected for any given material, decreases, and the TE performance degrades gradually due to the reduction in nH and enhancement in κL. Combining with the ZTs from several chalcopyrite compounds, it is believable that the best thermoelectric performance can be achieved at a certain ∆u value (∆u ≠ 0) for a specific space group if their crystal structures can be engineered. [ABSTRACT FROM AUTHOR]

AgInTe 2 compound has not received enough recognition in thermoelectrics, possibly due to the fact that the presence of Te vacancy (V Te ) and antisite defect of In at Ag site (In Ag ) degrades its electrical conductivity. In this work, we prepared the Ag 1-x InTe 2 compounds with substoichiometric amounts of Ag and observed an ultralow lattice thermal conductivity (κ L  = 0.1 Wm -1 K -1 ) for the sample at x = 0.15 and 814 K. This leads to more than 2-fold enhancement in the ZT value (ZT = 0.62) compared to the pristine AgInTe 2 . In addition, we have traced the origin of the untralow κ L using the Callaway model. The results attained in this work suggest that the engineering of the silver vacancy (V Ag ) concentration is still an effective way to manipulate the thermoelectric performance of AgInTe 2 , realized by the increased point defects and modified crystal structure distortion as the V Ag concentration increases.

In this work the chalcopyrite CuIn 3 Se 5-x Te x (x = 0~0.5) with space group through isoelectronic substitution of Te for Se have been prepared, and the crystal structure dilation has been observed with increasing Te content. This substitution allows the anion position displacement ∆u = 0.25-u to be zero at x ≈ 0.15. However, the material at x = 0.1 (∆u = 0.15 × 10 -3 ), which is the critical Te content, presents the best thermoelectric (TE) performance with dimensionless figure of merit ZT = 0.4 at 930 K. As x value increases from 0.1, the quality factor B, which informs about how large a ZT can be expected for any given material, decreases, and the TE performance degrades gradually due to the reduction in n H and enhancement in κ L . Combining with the ZTs from several chalcopyrite compounds, it is believable that the best thermoelectric performance can be achieved at a certain ∆u value (∆u ≠ 0) for a specific space group if their crystal structures can be engineered.