Illuminating the photophysical properties of multichromophoric organic semiconductors by using single particle spectroscopy
Energy transfer processes in multichromophoric organic materials are crucial for the performance of e.g. organic solar cells, organic light-emitting diodes, or light-harvesting systems. However, in conventional bulk measurements the processes cannot be examined properly due to the extraordinary morphological heterogeneities in these systems.
In contrast to this, by using single particle spectroscopy techniques we can avoid interactions between molecules and are therefore able to investigate processes that happen between the absorption and the emission of light in isolated molecules.
In this talk, I will present that we were able to investigate the temporal and spatial arrangement of transition dipole moments both in isolated planar carbazole macrocycles  as well as in isolated organometallic molecules . We found out that in both cases spontaneous symmetry breaking occurs that leads to a nondeterministic switching of the linear polarization the the emitted light.
In conjugated polymers we used photon correlation analysis to show that the photophysics changes at the transition from isolated polymer chains to the mesoscopic size regime in small aggregates which is a first step towards the bulk [3,4].
In combination with DNA nanotechnology we are able to build artificial multichromophoric systems to study their photophysical properties in a controlled manner and understand more in detail what processes dominate the photophysics .
1. V. Aggarwal et al., Nature Chem. 5, 964 (2013)
2. F. Steiner et al., J. Phys. Chem. Lett. 6, 999 (2015)
3. F. Steiner et al., Phys. Rev. Lett 112, 137402 (2014)
4. F. Steiner et al., J. Am. Chem. Soc. 139, 9787 (2017)
5. T. Schröder et al. Nano. Lett. 19(2), 1275 (2019)