Synergy of Rashba and Topological Effects for High-Performance Bismuth-Based Thermoelectrics

Lei Peng; Ruixiao Lian; Hongyu Chen; Ben Li; Yu Wu; Yuxiang Zheng; Hao Zhang

paper

Synergy of Rashba and Topological Effects for High-Performance Bismuth-Based Thermoelectrics

arXiv:2506.21479

Abstract

Band convergence is a key strategy for enhancing thermoelectric (TE) performance. Herein, we demonstrate a promising approach to enhance band convergence through inducing Rashba splitting in topological insulators. Theoretically designed Janus $β$ -Bi $_{2}$ Se $_{2}$ Te and $β$ -Bi $_{2}$ Te $_{2}$ Se exhibited inherent topological band inversion and Rashba splitting due to the strong spin-orbit coupling (SOC) with broken inversion symmetry. These characteristics synergistically improve band convergence, leading to a substantially enhanced power factor. Meanwhile, the Janus structural asymmetry suppresses lattice thermal conductivity. Consequently, Janus structures achieve boosted TE performance, especially for $β$ -Bi $_{2}$ Se $_{2}$ Te, peaking figure of merit ( $z T$ ) of 2.82. This work establishes a new framework for designing Janus topological compounds with high TE performance by the synergistic effect of Rashba splitting and band inversion.