TY  - GEN
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/37024/
A1  - Lindenthal, Sebastian Steffen
Y1  - 2025///
TI  - Synthesis, Purification, Doping of and Charge Transport in Low-Dimensional Carbon-Based Semiconductors
ID  - heidok37024
AV  - public
N2  - Confining the electron wave functions of the semi-metal graphene by reducing its dimensionality
leads to the opening of a bandgap. The resulting one-dimensional semiconductors like singlewalled carbon nanotubes (SWCNTs) or graphene nanoribbons (GNRs) are promising materials
for optoelectronic applications, due to their outstanding carrier mobilities and structuredependent tunable optical and electronic properties.
The fundamental properties of SWCNTs, such as exciton dynamics, charge transport and their
interaction with their environment have been studied thoroughly over the past decades and
SWCNTs have been successfully integrated into a variety of optoelectronic devices. However,
practical bottlenecks, associated with dispersion, purification and processing prevent scalable
device integration. This thesis provides optimized and detailed protocols to obtain high-purity
dispersions of long, defect-free semiconducting (6,5), (7,5) and large diameter semiconducting
SWCNTs via polymer-wrapping in organic solvents using shear force mixing as an exfoliation
method. Furthermore, a new highly soluble Lewis acid-based dopant is introduced for efficient
and stable p-type doping of small-diameter, polymer-wrapped SWCNTs. In contrast to
SWCNTs, many of the fundamental properties of atomically-precise GNRs are still under active
investigation, as they have been first synthesized almost a decade later than SWCNTs. This work
demonstrates that structural defects, which are commonly introduced during bottom-up synthesis
of GNRs, significantly alter absorption and emission features in dispersions of GNRs, as well as
the charge transport in GNR-based field-effect transistors. A simple method to heal defects in
GNR films and thus improve their charge transport properties is presented. This work also
provides first evidence of polaron formation in GNRs upon introduction of excess charge carriers
via chemical and electrochemical doping. The findings highlight similarities between
semiconducting polymers and GNRs, both in optical response to doping and charge transport in
devices. Within this thesis, these findings are contextualized within the broader research
landscape and implications for future studies are discussed.
CY  - Heidelberg
ER  -