Ultrafast Snapshots: Understanding the photoinduced charge transfer in donor–(bridge)–acceptor systems

Photoinduced charge transfer (CT) is a fundamental photophysical process that prevails in nature but also plays a pivotal role in various technological fields. This thesis describes spectroscopic studies on photoinduced CT in donor-bridge-acceptor (DBA) systems and their derivatives. Throughout this work, we employ femtosecond transient...

It's a Trap: Studying the quantum dot surface on an atomistic scale

Due to their size-dependent properties, high photoluminescence quantum yield and relatively cheap solution-based processing, colloidal quantum dots (QDs) are of great interest for application in optoelectronic devices. However, the efficiency of these devices is often limited by the presence of trap states: localized electronic states that lead...

Metal sulfides for gas sensing applications: devices and mechanisms

Nanostructured materials have attracted more and more attention in the applications of gas sensing due to their high specific surface area, numerous surface-active sites, as well as the effect of crystal facets with high surface reactivity. These kinds of gas sensors are mainly used for detecting air quality, environment situation, and breath...

Catalytic methane conversion with single-site porous catalysts: a computational approach

In this thesis we presented comprehensive studies on methane activation by binuclear Fe-oxo sites located in porous MOF and zeolite frameworks. Many of such studies have been previously performed, however the main focus was usually on the C-H bond activation of methane. Here we focused on the whole reaction mechanism including the activation of...

Modeling level alignment at interfaces in molecular junctions

Molecular devices are planned as alternative solutions for heat dissipation problems and reliable fabrication of nano-scale devices. However, it also opens up possibilities of combining many other degrees of freedom into functional device design. While they introduce interesting opportunities for study, they also demand a versatile, scalable...

Mechanism and Dynamics of Charge Transfer in Donor-Bridge-Acceptor Systems

Photoinduced charge transfer in organic materials is a fundamental process in various biological and technological areas. Donor-bridge-acceptor (DBA) molecules are used as model systems in numerous theoretical and experimental work to systematically study and unravel the underlying mechanisms of charge transfer. Despite the respectable successes...

Charge carrier transport at the nanoscale: Electron and hole transport in self-assembled discotic liquid crystals: Mobile ionic charges in nanocomposite solid electrolytes

This thesis explores some fundamental aspects of charge carrier transport at the nanoscale. The study is divided in two parts. In the first part, the structural, dynamical and vibrational properties of discotic liquid crystals are studied in relation to the potential of these self-assembled ‘mesophases’ to form molecular conducting wires....

On Conductance and Interface Effects in Molecular Devices

In this dissertation we discuss ab initio studies of quantum transport through single-molecule devices, using a combination of techniques from quantum chemistry and many-body physics. The molecular transport calculations discussed here are based on the "DFT+NEGF" approach to molecular transport. We first outline the density functional theory ...

Cyclohexane photo-catalytic oxidation on TiO2, an in situ ATR-FTIR mechanistic and kinetic study

Chemical processes are generally operated at elevated temperatures and pressures, and energy intensive separations are usually necessary. This thesis focuses on the production of cyclohexanone, which is an intermediate of high commercial importance as a result of its use in nylon-6 and nylon-6,6 production. Using TiO2 based photo-catalysis is a...

Opto-electronic properties of charged conjugated molecules

The aim of this thesis is to provide fundamental insight into the nature and opto-electronic properties of charge carriers on conjugated oligomers and polymers. Electronic structure, optical absorption properties and distribution of charge carriers along the chains of different conjugated materials are central issues of this thesis. In order to...