Prof. Martin Vácha: Nanoscale properties of organic and hybrid materials studied on the level of single molecules

Single molecule spectroscopy has undergone a remarkable development in the past decades, and its ability to unmask nanoscale phenomena that are otherwise inaccessible in ensemble experiments has found increasing use in physics and chemistry of soft matter, polymers and nanoscale materials, as well as in biology. This talk will introduce examples of recent research, ranging from conjugated polymers to supramolecular nanostructures to perovskite superlattices.

For the conjugated polymer polyfluorene, combined AFM, fluorescence microscopy, and single-chain electroluminescence provide a complex picture of its conformation-related photophysical properties. For supramolecular nanofibers self-assembled from anthracene-based chromophores, exceptionally long exciton transport over hundreds of nanometers is revealed by position dependent fluorescence lifetime technique, and the exciton diffusion is enhanced by the effect of surface plasmons. For CsPbBr3 quantum dot superlattices, long-range exciton migration to a localized energy site leads to collective blinking, formation of biexcitons and photon bunching due to exciton–biexciton cascade emission.

Martin Vácha received his Ph.D. from Charles University for work on low temperature high resolution optical spectroscopy. He has extensive experience in the fields of hole-burning and single-molecule spectroscopy gained during stays at various research institutions in Japan. He has been holding his current position at Institute of Science Tokyo since 2004. His research interests include nanoscale physical properties of organic and hybrid materials studied by single-molecule techniques. He has been visiting professor at Charles University since 2016, and Editor-in-Chief of NPG Asia Materials since 2012.