Electronic structure and transport in low dimensional systems

The work discusses the development of molecular electronics based on the possibility of the usage of anorganic quantum dots and organic molecules as basis material. Of special interest are the properties of semiconductor quantum dots and their modification due to the coupling of quantum dots from different materials. Eventually these are proper candidates to avoid the fast recombination of excitons which is a problem in many organic photovoltaic materials, by local separation of charge carriers. Another materials class investigated are the so called charge transfer dimers. On the way to usable molecular building blocks switching and rectification behavior are important properties, therefore they were of special interest in the investigation. Especially the usage of charge transfer materials in rectification was already suggested in the 70’s, but could be realized till now only with a quiet limited success. Already around the millennium it was shown that a too strong coupling between the components leads to a resymmetrization of the I-V-characteristics. For all systems the electronic structure was investigated by means of density functional theory. Additional the charge transport in between gold leads was computed based on non equilibrium Greens functions. For the system of coupled quantum dots it is shown how the combination of several gates can be used to adjust the transport properties. This work shows that the rectification effect within weakly coupled charge transfer systems stays also small because also in this case a resymmetrization of the I-V-characteristics takes place.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

TU Bergakademie Freiberg

Year

2019

Author dc:creator

• Liebing, Simon

Contributors dc:contributor

• Kortus, Jens
• Dasgupta, Indra

• physics
• DFT
• NEGF
• charge transfer dimers
• coupled quantum dots
• transport
• Physik
• Dichtefunktionaltheorie
• gekoppelte Quantenpunkte
• Ladungstransferdimere