  Hybrid halide perovskites are now considered as low-cost materials for
contemporary research in photovoltaics and nanophotonics. In particular,
because these materials can be solution processed, they represent a great hope
for obtaining low-cost devices. While the potential of 2D layered hybrid
perovskites for polaritonic devices operating at room temperature has been
demonstrated in the past, the potential of the 3D perovskites has been much
less explored for this particular application. Here, we report the strong
exciton-photon coupling with 3D bromide hybrid perovskite. Cavity polaritons
are experimentallly demonstrated from both reflectivity and photoluminescence
experiments, at room temperature, in a 3$\lambda$/2 planar microcavity
containing a large surface spin-coated $CH_3NH_3PbBr_3$ thin film. A
microcavity quality factor of 92 was found and a large Rabi splitting of 70 meV
was measured. This result paves the way to low-cost polaritonic devices
operating at room temperature, potentially electrically injectable as 3D hybrid
perovskites present good transport properties.

Optics;Mesoscale and Nanoscale Physics