Excitons are bound pairs of excited electrons and holes and play a crucial role in many photophysics processes occurring in Nature, such as photosynthesis and light absorption in organic and inorganic semiconductor materials. On the other hand, one of the most important phenomena in Quantum Electro-Dynamics (QED) is the so-called "Strong Coupling" regime, which appears when the interaction between light and excitons in matter is so strong that the photon and matter components mix to create hybrid light/matter states, called polaritons. Traditionally, this hybrid character has been used to achieve new functionalities in which polaritons are thought of as dressed photons, e.g. by exploiting exciton-exciton coupling to construct interacting photons.

However, over the last years, it has become clear that the strong coupling regime can be used with an alternative purpose: to significantly modify internal material properties and dynamics by dressing the excitons. In this seminar I plan to illustrate how the merging of these two fields of research (Excitons and QED) allows managing excitons to enhance energy transport in organic materials by taking advantage of the delocalized character of the polaritons and to alter the energy landscape of the organic molecules in such a way that photochemical reactions and even ground-state chemical reactions can be altered.