Ag₂Se Nanorod Arrays with Ultrahigh Room Temperature Thermoelectric Performance and Superior Mechanical Properties

Ag₂Se is an intriguing material for room-temperature energy harvesting. Herein, we report the fabrication of Ag₂Se nanorod arrays by glancing angle deposition technique (GLAD) followed by simple selenization in a two-zone furnace. Ag₂Se planar films of different thickness were also prepared. The unique tilted Ag₂Se nanorod arrays show excellent zT = 1.14 ± 0.09 and a power factor of 3229.21 ± 149.01 μW/m-K², respectively, at 300 K. The superior thermoelectric performance of Ag₂Se nanorod arrays compared to planar Ag₂Se films could be ascribed to the unique nanocolumnar architecture that not only facilitates efficient electron transport but also significantly scatters phonons at the interfaces. Furthermore, the nanoindentation measurements were performed to explore mechanical properties of the as-prepared films. The Ag₂Se nanorod arrays showed hardness values of 116.51 ± 4.25 MPa and elastic modulus of 10,966.01 ± 529.61 MPa, which are lowered by 51.8 and 45.6%, compared to Ag₂Se films, respectively. The synergetic dependence between the tilt structure and thermoelectric properties accompanied with the simultaneous improvement in mechanical properties opens a new avenue for the practical applications of Ag₂Se in next-generation flexible thermoelectric devices.