Enhancing Thermoelectric Performance in Cubic CuCdInSe₃ Compounds via Pressure-Induced Twin Boundary Engineering

Semiconductors with diamond-like structures have great potential as high-performance thermoelectric materials. However, they normally have relatively poor electrical transport properties, and conventional methods to improve their electrical transport usually lead to an increase in thermal conductivity, which is a major obstacle to achieving superior thermoelectric performance. Herein, by hot-pressing (HP) technology, we synthesized novel CuCdInSe3 compounds with a diamond-like, cubic zinc blende structure. High-density twin inversion boundaries are found in high-pressure-processed CuCdInSe3, improving the electrical transport property, which has achieved a PFmax value of 0.52 mWm(-1) K-2 at 500 K for CuCdInSe3 (HP-200 MPa). Randomly disordered cations in CuCdInSe3 induce an intensive alloying scattering, leading to a relatively low kappa(L) of 0.72 W m(-1) K-1 at 800 K (HP-300 MPa). The pressure-induced twin boundaries may work as an electron source that can effectively optimize the carrier concentration for CuCdInSe3. The CuCdInSe3 (HP-300 MPa) sample that achieves an improved ZT value of 0.47 at 800 K is attributed to the enhanced electrical transport properties combined with the low kappa, which is about seven times that of the sample (HP-50 MPa).