Structural Modularization of Cu<sub>2</sub>Te Leading to High Thermoelectric Performance near the Mott–Ioffe–Regel Limit
Kunpeng Zhao, Chenxi Zhu, Min Zhu, Hongyi Chen, Jingdan Lei, Qingyong Ren, Tian‐Ran Wei, Pengfei Qiu, Fangfang Xu, Lidong Chen, Jian He, Xun Shi
Abstract
Abstract To date, thermoelectric materials research stays focused on optimizing the material's band edge details and disfavors low mobility. Here, the paradigm is shifted from the band edge to the mobility edge, exploring high thermoelectricity near the border of band conduction and hopping. Through coalloying iodine and sulfur, the plain crystal structure is modularized of liquid‐like thermoelectric material Cu 2 Te with mosaic nanograins and the highly size mismatched S/Te sublattice that chemically quenches the Cu sublattice and drives the electronic states from itinerant to localized. A state‐of‐the‐art figure of merit of 1.4 is obtained at 850 K for Cu 2 (S 0.4 I 0.1 Te 0.5 ); and remarkably, it is achieved near the Mott–Ioffe–Regel limit unlike mainstream thermoelectric materials that are band conductors. Broadly, pairing structural modularization with the high performance near the Mott–Ioffe–Regel limit paves an important new path towards the rational design of high‐performance thermoelectric materials.