Anisotroper Ladungstransport in Nanokristallübergittern

01/07/2021 to 30/06/2022

Graphene, black phosphorus and transition metal dichalcogenides - all three materials have in common that charge carrier transport in these compounds depends on their crystalline orientation with respect to the electric field. This transport anisotropy is a result of the special crystal structure of their constituting atoms. Transport anisotropy has a profound impact on the optoelectronic properties of electric conductors with potential applications as polarized light detection devices and in valleytronics.
Colloidal semiconductor nanocrystals are often referred to as artificial atoms as their nowadays narrow size-distribution enables crystalline assemblies into closed-packed structures, and the discrete electronic states mimic those of single atoms. Superlattices of nanocrystals with macroscopic dimensions have been studied for over twenty-five years, but only recently it has become possible by means of tailoring the surface chemistry of nanocrystals to achieve ample electric conductivity in such superlattices. This enables addressing the question whether and under which conditions transport anisotropy prevails in nanocrystal superlattices and how it may be synthetically tailored.
The objective of this project is to demonstrate for the first time that transport anisotropy is present in superlattices of PbS nanocrystals and to derive general synthetic strategies for the design of other nanocrystal superlattices with direction-dependent charge carrier transport.