Exciton-polaritons are quasiparticles with hybrid light-matter character, offering a unique
combination of photonic properties, such as a light mass, with those of excitons, for example
strong nonlinearities and fast relaxation. Strong light-matter coupling enables a rich set
of polaritonic quantum phenomena as well as applications. While originally observed in inorganic
materials, organic semiconductors have recently attracted tremendous attention since their large
oscillator strength facilitates particularly strong light-matter coupling and enabled polariton
formation at room temperature. In particular, electrical excitation is pursued to apply these
quantum-mechanical effects in practical polariton devices. However, a lack of organic materials
with sufficiently high charge-carrier mobility and suitable device architectures impede their full
utilization.
Nanomaterials, in particular low-dimensional materials, present a novel material class that
combines the excitonic properties of organic and electric characteristics of inorganic materials.
In this thesis, single-walled carbon nanotubes (SWCNTs) were employed to demonstrate, for
the first time, exciton-polariton formation in the near infrared (nIR) at room temperature.
SWCNTs are identified as an ideal material facilitating strong light-matter coupling due to
their high oscillator strength. Moreover, by implementing a strongly coupled microcavity into
a light-emitting field effect transistor (LEFET), electrically pumped polariton emission at high
current density was observed. These practical polariton devices emit in ranges relevant for
telecommunication and support high currents due to the excellent optoelectronic properties of
SWCNTs. Pumping polaritons at high rates presents a major step towards electrical lasing with
carbon-based materials.
For the realization of these experiments it was crucial to overcome current limitations in
post-growth sorting of SWCNTs, which are intrinsically restricted to low-volume and damage
the nanotubes. For this purpose, selective polymer wrapping by high-speed shear-force mixing,
which can be easily scaled up, was developed. By using shear forces, the SWCNT-yield was
drastically increased while, at the same time, the SWCNT-quality could be improved. In addition
to strong light-matter coupling and polariton emission, the selected SWCNTs were employed in
organic light-emitting diodes. These devices showed pure nIR emission with narrow linewidth at
efficient electrical performance. This work paves the way for fundamental investigations as well
as advanced applications of SWCNT-based optoelectronic devices
