• disorder
• excitons
• optical microcavities
• photoluminescence
• polaritons
• thin films

In this thesis we have studied the physics of strongly coupled J-aggregate microcav-
ities.

We addressed the problem of disorder in organic microcavities,
previously approached only with a classical macroscopic method.
We numerically
analyzed the effect of disorder at a microscopic level, characterizing the polariton localization properties.
The localization at the bottom of lower polariton branch has been
studied in detail, for its importance in view of the polariton condensation.
We also addressed the timescales on which the localization is expected to be of experimental relevance, calculating the time evolution of a polariton wavepacket.

A second issue of this thesis is the construction of a model for the optical dynamics
of J-aggregate microcavities.
We build our model from a
microscopic approach: first describing the optically active material, the J-aggregate
film, following a well-known and successful approach, and then generalizing the model
for the bare film to the microcavity case.
We simulated the bare film absorption and
emission spectra, fitting our parameter to recover their FWHM behavior with the
temperature.
We calculated the polariton relaxation dynamics following the scattering with molecular vibrations, we built a rate equation, solved it and the angle-resolved photoluminescence.
Our model explains the thermal activation of the
upper polariton photoluminescence and its dependence on the Rabi splitting value, demonstrating the occurrence of a relaxation bottleneck inside the, so-called, exciton reservoir.