Enhanced thermoelectric performance of a chalcopyrite compound Culn3Se5-xTex (x=0∼0.5) through crystal structure engineering

In this work the chalcopyrite CuIn3Se5-xTex (x = 0-0.5) with space group l (4) over bar 2m 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 Delta U = 0.25-U to be zero at x approximate to 0.15. However, the material at x = 0.1 (Delta U = 0.15 x 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 kappa(L). Combining with the ZTs from several chalcopyrite compounds, it is believable that the best thermoelectric performance can be achieved at a certain Delta u value (Delta U not equal 0) for a specific space group if their crystal structures can be engineered.