Special Seminar: Embrace the darkness  From singlet fission to exciton-polaritons

In the Musser lab, we are broadly interested in understanding and exploiting the light-matter interactions of organic semiconductors. These processes underpin the operation of LEDs and solar cells, and new materials concepts promise applications from carrier multiplication in solar cells to ultrapowerful photocatalysts to quantum information science. Yet to turn this promise into a reality and improve on current applications, we require a deeper understanding of the processes of relaxation in these materials and the types of electronic state that are involved. Using a suite of tools based on ultrafast laser spectroscopy, we aim to provide a more detailed picture of the structure-function relationships that govern the photophysical dynamics. Frequently, the processes in these materials can be framed in terms of an interplay between bright and dark states, defined by their ability to optically connect to the ground state. But we are increasingly drawn to systems that don’t fit the neat bright-dark dichotomy. The ‘grey’ states in these materials mix the properties of both manifolds, whether due to disorder or higher-order state couplings that are frequently overlooked. Our results from simple molecular dimers to complex thin-film microcavitiesforce us to reevaluate our basic pictures of molecular photophysics and presenting new opportunities for materials design.  space.