High thermoelectric performance induced by quasi-one-dimensional structure in X(Cs & Rb)2PtTe2.

In the era of encouraging green and sustainable energy, thermoelectric (TE) materials play a crucial role in directly converting heat energy into electrical energy. This study reports on a promising quasi-one-dimensional TE material, X(Cs & Rb)2PtTe2, which simultaneously achieves ultralow lattice thermal conductivity (κL) and a high power factor. Using first-principles calculations, anharmonic lattice dynamics, self-consistent phonon theory, and the Boltzmann equation, we systematically investigated the structural stability and TE transport properties of X(Cs & Rb)2PtTe2. Due to the confinement effects induced by reduced dimensionality, with quartic anharmonicity corrections, at 300 K, the κL values of Cs2PtTe2 and Rb2PtTe2 in the directions perpendicular to the Pt-Te chains are only 0.14 and 0.12 W m-1 K-1, making them excellent thermal insulators. Additionally, their band structures exhibit "pudding-mold type" characteristics, resulting in high Seebeck coefficients and power factors. At room temperature, the optimal TE figure of merit (ZT) for n-type doped Cs2PtTe2 and Rb2PtTe2 in the directions perpendicular to the Pt-Te chains is 1.12 and 1.68, respectively. At 800 K, the ZT values for n-type doped Cs2PtTe2 and Rb2PtTe2 reach 4.13 and 5.52. Their TE conversion efficiency significantly surpasses that of traditional TE materials, making them competitive with other transducer devices and demonstrating substantial commercial potential.