Abstract

Next generation photovoltaic materials, including polymers and organometal halide perovskites, offer tremendous potential for low cost clean energy. However, the design of more effective materials is hindered by lack of understanding of the mechanisms by which these complex and disordered materials convert light to electricity. We have developed a series of time-resolved optical spectroscopy experiments that resolve different properties of photoexcitations in these materials.

In this talk, I will review some of our recent insights from ultrafast spectroscopy. In organic semiconductors, these highlights include evidence for ultrafast long-range charge separation,1 as well as the roles of delocalised excitons and disordered phases, ultrafast light harvesting, and singlet exciton fission. The organic materials will be contrasted with efficient organometal halide perovskites, where we find efficient free charge photogeneration.