Off-centering effect and crystal symmetry modification lead to high thermoelectric performance in diamondoid Cu<sub>2</sub>SnSe<sub>3</sub>

作者：Pengpeng Chen, Shulin Bai, Yi Wen, Yichen Li, Zihao Zhao, Dezheng Gao, Houdong Huang, Yixuan Hu, Tian Gao, Lei Wang, Shaoping Zhan, Xiang Gao, Xianli Su, Hongyao Xie, Lidong Zhao · 发表于：National Science Open · 年份：2025 · DOI：10.1360/nso/20250004 · 被引用次数：13 · 研究领域：Advanced Thermoelectric Materials and Devices、nanoparticles nucleation surface interactions、Optical properties and cooling technologies in crystalline materials

Recently, dimensionless figure of merit ( ZT ) beyond 1.0 has been demonstrated in diamondoid Cu 2 SnSe 3 , positioning it as a low-cost and ecofriendly thermoelectric alternative, and sparking intense interest in further optimizing its thermoelectric properties. However, its intrinsic monoclinic structure and the compact packing of tetrahedral coordination lead to a light valence band and high thermal conductivity, which impede further performance improvement in Cu 2 SnSe 3 . Thus, developing effective approaches to altering the local structure of Cu 2 SnSe 3 is important for further optimizing its thermoelectric performance. Herein, we identified and thoroughly investigated the atomic off-centering behavior in Cu 2 SnSe 3 , and demonstrated the electronic and phonon transport properties of Cu 2 SnSe 3 can be significantly enhanced by carefully modifying its monoclinic lattice into a distorted zinc-blende cubic structure via introducing Cd and off-centering Ag elements. This structure transition leads to band convergence and a reduction in the deformation potential of the material, resulting in a 7-fold enhancement in the density-of-state effective mass and an 85% increase in carrier mobility. Additionally, the off-centering effect results in strong acoustic-optical phonon scattering and an ultra-low lattice thermal conductivity of 0.3 W m −1 K −1 . Consequently, a maximum ZT of 1.3 was obtained at 800 K for the Cu 1.85 Ag 0.15 Sn 0.9 Cd 0.1 Se 3 .