Transmission and Scanning Transmission Electron Microscopy have played a critical role in the development of cadmium-based colloidal quantum dots. However, grey-scale images and lattice measurements are insufficient to accurately characterize the complex heterostructures of emergent nanocrystal emitters. The advent of modern energy dispersive spectroscopy (EDS) systems coupled with bright electron sources has greatly enhanced the ability to visualize the chemical composition of nanomaterials with sub-nm resolution. Specifically, the quad-EDS detector design of the Tecnai Osiris enables rapid elemental mapping of colloidal nanocrystals prior to the onset of obvious beam damage. In conjunction with our optical correlation method, we have utilized HRSTEM and STEM-EDS to directly investigate the affect specific chemical and structural motifs have on the individual particles optical properties. Recent results on giant shelled CdSe/CdS, graded alloy CdSSe/CdS and Zn<sub>3</sub>N<sub>2</sub> nanocrystals will be presented. Zinc Nitride nanocrystals, a promising earth-abundant fluorophore, pose a significant challenge due to their air and beam sensitivity. Additionally, sample preparation considerations and progress towards STEM-EDS tomography of individual core/shell nanocrystals will be discussed.

Electron microscopy in color: Revealing chemical complexity in emergent nanocrystal systems utilizing advanced STEM-EDS

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.