The interaction between
molecular electronic transitions and electromagnetic
fields can be enlarged to the point where distinct hybrid light–matter
states, polaritons, emerge. The photonic contribution to these states
results in increased complexity as well as an opening to modify the
photophysics and photochemistry beyond what normally can be seen in
organic molecules. It is today evident that polaritons offer opportunities
for molecular photochemistry and photophysics, which has caused an
ever-rising interest in the field. Focusing on the experimental landmarks,
this review takes its reader from the advent of the field of polaritonic
chemistry, over the split into polariton chemistry and photochemistry,
to present day status within polaritonic photochemistry and photophysics.
To introduce the field, the review starts with a general description
of light–matter interactions, how to enhance these, and what
characterizes the coupling strength. Then the photochemistry and photophysics
of strongly coupled systems using Fabry–Perot and plasmonic
cavities are described. This is followed by a description of room-temperature
Bose–Einstein condensation/polariton lasing in polaritonic
systems. The review ends with a discussion on the benefits, limitations,
and future developments of strong exciton–photon coupling using
organic molecules.