2D Single‐Layer π‐Conjugated Nickel Bis(dithiolene) Complex: A Good‐Electron‐Poor‐Phonon Thermoelectric Material

Abstract

AbstractRecently, the 2D d8 planar π‐conjugated transition metal complexes have gained extensive attention owing to their extra‐high electrical conductivity. Meanwhile, low lattice thermal conductivities can be expected for their soft and microporous structures, suggesting very promising thermoelectric applications. Herein, based on first‐principles calculations and molecular dynamics simulations, it is identified that monolayered 2D nickel bis(dithiolene) complex, (NiC4S4)n, is indeed such a material that exhibits exceptionally high electron mobility, low lattice thermal conductivity, and thereby excellent thermoelectric performance. The calculated figure of merit at 300 K can reach up to 0.92 for a perfect nanosheet. At the same time, the mechanism behind is uncovered, that is, the weak electron‐acoustic‐phonon coupling allowing high electron mobility, and its microporous structure decreasing the thermal transport. The surprisingly weak electron‐acoustic‐phonon coupling arises from mixed bonding–antibonding nature of conduction band. The finding opens a new opportunity for these 2D coordination complexes as potential thermoelectric materials.