A molecule strongly coupled to an optical cavity (by embedding it between two parallel mirrors, for instance) can intensely absorb light at frequencies for which its intrinsic absorption is practically none, or emit light at spectral ranges at which the uncoupled system barely shows luminescence. These effects arise as a result of the reconfiguration of the electronic structure of the molecules and the optical modes of the cavity caused by their strong-coupling. In this regime, the ensemble must be described by hybrid light-matter states, also known as polaritons, and not anymore by individual photonic or electronic ones. In this talk, different ways to controllably modify the optical response of molecular materials by tailoring the optical environment will be overviewed. Experimental and theoretical results on the spectral and angular optical absorption and emission characteristics of molecular light harvesters and emitters when operating under weak, strong and ultra-strong exciton-photon coupling regimes will be discussed. The relevance of these effects to enhance the performance of molecular materials in different fields, such as photovoltaics or photodetection, will also be analysed.
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 V. Esteso, L. Caliò, H. Espinós, G. Lavarda, T. Torres, J.Feist, F.J. Garcia-Vidal, G. Bottari, H. Míguez. Light Harvesting Properties of a Subphthalocyanine Solar Absorber Coupled to an Optical Cavity. Sol. RRL 2021, 2100308. https://doi.org/10.1002/solr.202100308.
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