Seminar from Aaron Lindenberg - 13 February

Transient structure determination and polaron formation in the hybrid perovskites.



Aaron Lindenberg



Stanford Department of Materials Science and Engineering and SLAC National Accelerator Laboratory



Novel characterization techniques developed over the past two decades have revolutionized our ability to visualize the microscopic, atomic-scale processes that determine the functional properties of materials. The overarching challenge here is that the relevant time-scales and length-scales for these processes are typically 10^-13 seconds (100 femtoseconds) and 10^-10 m (1 Angstrom) such that our view of how a material or device functions is often blurred out in time or in space. Real-time x-ray and electron scattering techniques, which are directly sensitive to the dynamical response of atoms, provide powerful means for probing these processes which often underlie optoelectronic functionality. In this talk I will present recent progress applying such techniques to the hybrid perovskites, probing the local structural rearrangements and charge separation dynamics that occur following above gap photo-excitation on Angstrom and nanometer length-scales. These measurements provide new insight into the role of ultrafast atomic-scale distortions and polaron formation in enabling the unique optoelectronic properties of these materials.