(Invited) Structural Origins of Electronic Properties and Transport States in Halide Perovskites

Abstract

The Asbury group has developed ultrafast infrared spectroscopy techniques to examine electronic processes in materials for photocatalysis and energy harvesting with particular focus on the influence that underlying molecular structures and structural fluctuations have on those processes. This talk will focus on the application of ultrafast infrared spectroscopy to examine the coupling of temperature-dependent lattice fluctuations on electronic transport states in perovskite photovoltaic and photocatalytic materials. The transition of photogenerated charges from free carrier states to large polarons to trapped states is directly observed through the corresponding mid-infrared transitions. Temperature dependent amplitudes of lattice fluctuations are examined through dephasing of vibrational modes and correlated with the nature of the transport states. Ligands attached to surface states provide unique insights into the nature of charge traps and help define pathways for their elimination. The ability to link underlying molecular structures with electronic properties provides unique insights that lead to new design rules in support of continued materials development efforts.