Crystal symmetry modification enables high-ranged in-plane thermoelectric performance in n-type SnSe crystals
Haonan Shi, Yi Wen, Shulin Bai, Cheng Chang, Lizhong Su, Tian Gao, Shibo Liu, Dongrui Liu, Bingchao Qin, Yongxin Qin, Huiqiang Liang, Xin Qian, Zhenghao Hou, Xiang Gao, Tianhang Zhou, Qing Tan, Li‐Dong Zhao
Abstract
Abstract SnSe crystal has witnessed significant advancements as a promising thermoelectric material over the past decade. Its in-plane direction shows robust mechanical strength for practical thermoelectric applications. Herein, we optimize the in-plane thermoelectric performance of n -type SnSe by crystal symmetry modification. In particular, we find that Te and Mo alloying continuously enhances the crystal symmetry, thereby increasing the carrier mobility to ~ 422 cm 2 V −1 s −1 . Simultaneously, the conduction bands converge with the symmetry modification, further improving the electrical transport. Additionally, the lattice thermal conductivity is limited to ~ 1.1 W m −1 K −1 due to the softness of both acoustic and optical branches. Consequently, we achieve a power factor of ~ 28 μW cm −1 K −2 and ZT of ~ 0.6 in n -type SnSe at 300 K. The average ZT reaches ~ 0.89 at 300−723 K. The single-leg device based on the obtained n -type SnSe shows a remarkable efficiency of ~ 5.3% under the Δ T of ~ 300 K, which is the highest reported in n -type SnSe. This work demonstrates the substantial potential of SnSe for practical applications of power generation and waste heat recovery.