2D Chalcogenide Nanoplate Assemblies for Thermoelectric Applications.

Abstract

Engineered atomic dislocations have been used to create a novel, Sb₂ Te₃ nanoplate-like architecture that exhibits a unique antisymmetric chirality. High-resolution transmission electron microscopy (HRTEM) coupled with atomic force microscopy and X-ray photoelectron spectroscopy reveals the architectures to be extremely well ordered with little residual strain. Surface modification of these topologically complex macrostructures (≈3 µm) has been achieved by direct growth of metallic Ag nanoparticles onto the edge sites of the Sb₂ Te₃ . Again, HRTEM shows this nanoparticle decoration to be atomically sharp at the boundaries and regularly spaced along the selvedge of the nanostructure. Transport experiments of densified films of these assemblies exhibit marked increases in carrier density after nanoengineering, yielding 3.5 × 10⁴ S m^-1 in electrical conductivity. An increased Seebeck coefficient by 20% in parallel with electrical conductivity is also observed. This gives a thermoelectric power factor of 371 µW m^-1 K^-2 , which is the highest value for a flexible, freestanding film to date. These results suggest an entirely new direction in the search for wearable power harvesters based on topologically complex, low-dimensional nanoassemblies.