  When doped into a certain range of charge carrier concentrations, MoS2
departs from its pristine semiconducting character to become a strongly
correlated material characterized by exotic phenomena such as charge density
waves or superconductivity. However, the required doping levels are typically
achieved using ionic-liquid gating or air-sensitive alkali-ion intercalation,
which are not compatible with standard device fabrication processes. Here, we
report on the emergence of superconductivity and a charge density wave phase in
air-stable organic cation intercalated MoS2 crystals. By selecting two
different molecular guests, we show that these correlated electronic phases
depend dramatically on the intercalated cation, demonstrating the potential of
organic ion intercalation to finely tune the properties of 2D materials.
Moreover, we find that a fully developed zero-resistance state is not reached
in few-nm-thick flakes, indicating the presence of three-dimensional
superconductive paths which are severed by the mechanical exfoliation. We
ascribe this behavior to an inhomogeneous charge carrier distribution, which we
probe at the nanoscale using scanning near-field optical microscopy. Our
results establish organic-ion intercalated MoS2 as a platform to study the
emergence and modulation of correlated electronic phases.
