Photophysics and optoelectronics of functionalized acenes and anthradithiophenes in cavities

Understanding strong exciton-photon coupling in organic films in microcavities, and how the properties of polariton states may contribute to the performance of organic (opto)electronic devices are of considerable interest. To efficiently utilize strong exciton–photon coupling to enhance device performance, it is necessary to establish how the photophysics of polaritons in organic electronic materials depends on molecular properties and microcavity configurations. We present a systematic study of strong coupling in functionalized tetracenes (R-Tc) and anthradithiophenes (R-ADT) depending on film crystallinity, morphology, placement in the cavity (to achieve various degrees of overlap with the cavity electric field), and cavity design. By varying the concentrations of R-Tc and R-ADT molecules in blends with a polymer, we examine the effects of intermolecular interactions on the polariton formation and properties. We observe cavity-dependent formation of the triplet-pair states in the process of singlet fission in these materials and establish how this process depends on the derivative, film properties, and cavity characteristics. We further discuss energy and charge transfer processes in optoelectronic devices containing strongly cavity-coupled donor molecules and acceptors.