Visualizing Ultrafast Structural Deformations in Photoexcited Nanocrystals

In the last decades colloidal nanocrystals have become ubiquitous materials in optoelectronic and solar energy applications ranging from light-emitting diodes to artificial photosynthesis. Pushing performance limits in these applications beyond the state of the art requires understanding and controlling microscopic electronic and structural responses in the ensembles of photoexcited nanocrystals. Particularly, understanding the origins of nonradiative losses such as carrier trapping and hot carrier relaxation is critical to increase the utilization of excited electronic states for efficient energy transport and conversion. In this talk, I will highlight the use of pump-probe electron diffraction and X-ray scattering approaches to unravel electron – phonon couplings in colloidal nanocrystals to investigate the atomistic origins of nonradiative relaxation and associated transient lattice deformations. I will present our recent work resolving dynamic lattice responses in photoexcited II-VI, IV-VI and metallic nanocrystals which reveales dynamic structure - property relationships key to manipulating photocatalytic functionalities in these nanomaterials.<br/>[1] B. Guzelturk, B. Cotts. D. Jasrasaria, J. Philbin, et al., Nature Communication 12, 1860 (2021)<br/>[2] B. Guzelturk, et al., ACS Nano 14, 4792 (2020)