Enhancement of Thermoelectric Performance in CuSbSe₂ Nanoplate-Based Pellets by Texture Engineering and Carrier Concentration Optimization

This work reports the thermoelectric properties of the CuSbSe₂-x mol% PtTe₂ (x = 0, 0.5, 1.0, 1.5, and 2.0) pellets composed of highly oriented single crystalline nanoplates. CuSbSe₂-PtTe₂ single crystalline nanoplates are prepared by a wet-chemical process, and the pellets are prepared through a bottom-up self-assembly of the CuSbSe₂-PtTe₂ nanoplates and spark plasma sintering (SPS) process. X-ray diffraction and field emission scanning electron microscopic analyses show a highly textured nature with an orientation factor of ≈0.8 for (00l) facets along the primary surface of the pellets (in-plane, perpendicular to the SPS pressure). By this way, bulk-single-crystal-like electrical and thermal transport properties with a strong anisotropy are obtained, which results in an effective optimization on thermoelectric performance. The maximum in-plane thermoelectric figure-of-merit ZT value reaches 0.50 at 673 K for CuSbSe₂-2.0 mol% PtTe₂ pellet, which is about five times higher than the in-plane ZT (0.10) for pure CuSbSe₂.