This research aims to elucidate how the atomic structure of core/shell nanocrystals (quantum dots) impacts their photophysics. In this work, Prof. Sandra Rosenthal and Prof. James McBride of Vanderbilt University leverage modern chemical techniques to synthesize quantum dots of varying composition and shell coverage, which will then be imaged with atomic resolution via aberration-corrected scanning transmission electron microscopy (STEM). Further, these structures will be characterized utilizing single nanocrystal spectroscopy as well as ultrafast fluorescence upconversion spectroscopy to obtain blinking statistics in addition to exciton dynamics. Ultimately, methodologies to perform correlated single nanocrystal spectroscopy and aberration-corrected STEM will be developed in order to precisely determine which specific nanostructures provide the highest fluorescence yield, photostability and reduced blinking; information that is lost in ensemble measurements.
The utilization of state-of-the-art electron microscopy in conjunction with single molecule fluorescence techniques will clarify the true effect of shell coverage and composition. This will have immediate impact on commercial applications utilizing quantum dot fluorescence as biological probes and current efforts to incorporate highly fluorescent and stable quantum dots for solid-state lighting. Improvement in fluorescent probes will lead to higher sensitivity for drug discovery applications as well as allowing for direct measurements of biological dynamics at the single molecule level. Additionally, perfecting quantum dot design will greatly enhance the efficiency and extend the lifetime of quantum dot-based solid state lighting devices. Undergraduate research will play an integral role in the synthesis and characterization of the nanocrystals, while fostering an understanding of how to devise, implement an experiment, and how to interpret and present data. A kit demonstrating the size-dependent quantum dot fluorescence as an introduction to 'nano' will be developed for the Vanderbilt Students Volunteers for Science organization (VSVS), which arranged more than four hundred classroom visits last year and will be extended to rural TN via an NSF EPSCoR award.
