Strong light-molecule coupling : routes to new hybrid materials

Overview & Synopsis

Over the past 15 years, light-matter strong coupling involving organic materials has been of increasing interest due to the very large energy splitting such systems exhibit between the two hybrid light-matter states, also known as the polaritonic states typically denoted P+ and P-. The large energy splitting, so-called Rabi splitting, is the result of the high transition dipole moments of the molecules and the small mode volumes of micro-metallic Fabry-Pérot (FP) cavities or surface plasmons used in these studies. Rabi-splittings -1 eV have been observed, often representing a significant fraction of the electronic transition energy in which case the system is said to be in the ultra-strong coupling regime. ln this regime the physical chemistry of molecules or the properties of materials of the coupied system should be modified. lndeed, it has already been shown to affect the relaxation pathways in the coupled system, the rates of photochemical reactions, thework-function and conductivity of organic-semiconductors in the dark, among other things. A recent thermodynamic study demonstrated that the ground state energy can also be shifted in theultra-strong coupling regime. Moreover, the strong coupling is not limited to electronic transitions, but also can be used to perturb the ground-state vibrations of molecules in the infrared region. Ali these results suggest that light-molecule strong coupling has much potential for material and molecular science and therefore merits further study.