Low‐Symmetry PdSe<sub>2</sub> for High Performance Thermoelectric Applications
Yunshan Zhao, Peng Yu, Gang Zhang, Minglei Sun, Dongzhi Chi, Kedar Hippalgaonkar, John T. L. Thong, Jing Wu
Abstract
Abstract As an emerging member in 2D materials, pentagonal palladium diselenide (PdSe 2 ) has interesting ambipolar charge transport behavior with high air‐stability and shows great potential in nanoelectronics and optoelectronics. Moreover, the puckered pentagon structure in PdSe 2 results in an intrinsic low lattice thermal conductivity, which makes PdSe 2 a superior material prospect for thermoelectric (TE) applications. However, its TE properties have yet to be experimentally demonstrated. Here, the TE transport in 2D PdSe 2 with a low‐symmetry pentagonal lattice is probed for the first time. By thickness‐engineering, it is demonstrated that the TE property of PdSe 2 can be effectively manipulated due to its sensitive dependence on the interlayer coupling originating from the special lattice structure. The TE performance can be largely enhanced benefiting from the high band convergence and quantum confinement in thinner PdSe 2 flakes. A power factor as high as 1.5 mW m −1 K −2 can be achieved for a PdSe 2 flake with a thickness of 5 nm. This work provides the first TE study on a pentagonal lattice as opposed to hexagonal lattices that dominate the 2D layered material family. The unique lattice structure with special interlayer interaction in PdSe 2 opens up new pathways for TE applications, low‐dimensional electronics, and quantum devices.