CaSTL Seminar by John B. Asbury

Molecules figure prominently in the electronic properties of emerging materials ranging from organic photovoltaics (OPVs) to colloidal quantum dots (CQDs) and organo-halide perovskites used in solution processed photovoltaics and photodetectors.  The Asbury group has pioneered the development of ultrafast infrared spectroscopy techniques to examine electronic processes in materials with particular focus on the influence that underlying molecular structures have on those processes.  This talk will focus on two applications of infrared spectroscopy to examine electronic processes in OPV and perovskite photovoltaic materials.  In the first application, the influence of molecular structure and material morphology on charge delocalization is correlated with the corresponding quantum yield for charge generation and OPV device performance.  In the second application, the surface chemistry of ligand-nanocrystal interactions and their corresponding influences on the density and energetic distribution of charge trap states in perovskite photovoltaic materials are examined.  Direct observation of ligands attached to surface trap states provide unique insights into the nature of charge traps and helps define pathways for their elimination.  In both cases, the ability to link underlying molecular structures with electrical properties provides unique insights that lead to new design rules in support of continued materials development efforts.