  The pioneering experiments of Karl H. Drexhage explained the classical
interaction of light with matter and the modification of the decay rates of an
emitter.1 Here, we tried to mimic these experiments in a slightly different
configuration and measured the electron mobility of a thin film semiconductor
from weak to strong coupling regime. Perylene diimide (organic semiconductor
dye) molecules are deposited on a MOSFET device. The refractive index mismatch
between the silicon/silicon dioxide layer and the dye molecules forms an
interference pattern. The frequency of the interference lines is tuned by
changing the thickness of the organic semiconductor. Interestingly, we observed
an increase in the electron mobility of the active layer once the system slowly
entered into strong coupling condition in a {\lambda} cavity. Whereas resonance
tuning of a {\lambda}/2 cavity does not affect the electron transport,
suggesting the system is still in the weak coupling regime. These results are
further correlated by optical measurements and transfer matrix simulations. The
increase in electron mobility is not large due to high dissipation or
low-quality factors of the cavity modes. However, the mirrorless configuration
presented here may offer a simpler way of studying the properties of the
polaritonic states.
