The Sadtler research group uses light to image and control chemical transformations in inorganic nanostructures.
Imaging heterogeneity in the reactivity of semiconductor nanocrystals. Unlike molecular synthesis in which a single desired product can often be isolated, the synthesis of nanoscale particles inherently produces a distribution of sizes and shapes. We make measurements one particle at a time to understand how this heterogeneity impacts the chemical reactivity of colloidal semiconductor nanocrystals. Currently, we are using single-molecule fluorescence microscopy and chemically activated fluorogenic probes to map nanoscale spatial variations in the photocatalytic activity of semiconductor particles. These studies have provided new insights into how the concentration and distribution of oxygen vacancies control the activity of metal oxide semiconductors for fuel-forming reactions
Growth of inorganic nanostructures under external stimuli. Chemists typically use parameters such as temperature, pressure, and concentration to direct chemical transformations in molecules and materials. Many classes of materials are also responsive to external stimuli, including light, electrochemical potential, and mechanical strain. We are designing adaptive inorganic materials that adjust their growth in response to multiple external stimuli to synthesize complex nanostructures and metastable materials that cannot be made by traditional synthetic methods.
Chemical transformations in nanoscale materials. Anion exchange is a facile, post-synthetic method to tune the emission wavelength of colloidal cesium lead halide (CsPbX3, X = Cl, Br, I) perovskite nanocrystals. However, heterogeneity in the size and composition of these nanocrystals will lower the color purity of their emission, which is undesirable in applications such as light-emitting diodes. We are using single-particle fluorescence microscopy to understand how nanocrystal size, solid-state miscibility, and structural heterogeneity impact the chemical reactivity and resulting optical properties of semiconductor nanocrystals during solid-state transformations like anion exchange in CsPbX3.