Enhancing Thermoelectric Properties of InTe Nanoprecipitate-Embedded Sn_1–xIn_xTe Microcrystals through Anharmonicity and Strain Engineering

As one of Pb-free thermoelectric materials, tin telluride (SnTe) has received extensive attention. Here, we report InTe nanoprecipitate-embedded Sn1–xInxTe microcrystals with an improved thermoelectric performance prepared via a facile solvothermal method. In dopants can strikingly enhance the room-temperature thermopower from ∼23 to ∼88 μV K–1, which is attributed to the distortion of density of states near the Fermi level in the valence band of Sn1–xInxTe. Our detailed structural characterizations indicate that point defects, anharmonic bonding, dislocations, and strain around nanoprecipitates can effectively strengthen phonon scattering and, in turn, significantly reduce lattice thermal conductivity. Raman spectroscopy analysis shows that optical phonon modes shift toward higher wavenumber, indicating the change of the bonding force and the chemical environment in the system, which facilitates additional resistance to propagate heat-carrying phonons. Finally, a high power factor of ∼21.8 μW cm–1 K–2 and a corresponding figure of merit, ZT, of ∼0.78 are obtained in Sn0.99In0.01Te at 773 K. This study explores the fundamental In-doping mechanisms in a SnTe matrix and demonstrates anharmonicity and strain engineering as effective approaches to boosting thermoelectric performance, which provides a new avenue in achieving high-performance thermoelectric properties of materials.