Strain‐Mediated Lattice Rotation Design for Enhancing Thermoelectric Performance in Bi2S2Se

Abstract

AbstractA unique strain‐mediated lattice rotation strategy is introduced via nanocompositing to upsurge the optimized limits in the composition‐to‐structural pathway on rationally engineering the efficient thermoelectric material. In this study, a special lattice rotation via strain engineering is realized to optimize the desired electronic and chemical environment for enhancing thermoelectric properties in n‐type Bi2S2Se. This approach results in a unique transport phenomenon to assist high‐energy electrons in transferring through the optimized transport channels, and appropriate structure disparity to significantly localize phonons. As a result, Sb over Cl doping in Bi2S2Se gently reduces Eg and introduces defect states in bandgap with shifting down the Fermi level, thus causing increase in carrier concentration, which contributes to a higher power factor of ≈7.18 µW cm−1 K−2 (at T = 773 K). Besides, a lower thermal conductivity of ≈0.49 W m−1 K−1 is driven through lattice strain and defect engineering. Consequently, an ultra‐high ZTmax = 1.13 (at T = 773 K) and a high ZTave = 0.54 (323 K‐773 K) are realized. This study not only leads to an extraordinary thermoelectric performance but also reveals a unique paradigm for electron transportation and phonon localization via lattice strain engineering.