Brandi Cossairt (University of Washington)

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Location: B01 McCourtney Hall

Abstract:  We are interested in developing colloidal nanocrystals for applications in classical and quantum light technologies. Our approach leverages the extraordinary properties of nanoscale systems and applies foundational design principles from molecular inorganic chemistry. In this talk we will examine strategies to overcome challenges in atomically precise synthesis and single particle placement by exploiting the extremes of nanocrystal size.  

First, the formation of kinetically persistent cluster molecules as intermediates in the nucleation of colloidal nanocrystals makes these materials of great interest for determining and controlling mechanisms of crystal growth. These clusters are also high-fidelity models for understanding the structure, bonding, and reactivity of larger nanocrystals, which are characterized by ensemble heterogeneity. We will explore families of atomically precise CdSe and InP semiconductor clusters. Different structurally distinct members of these families will be presented along with experiments demonstrating their interconversion and conversion to larger nanocrystals. Methods to distinguish reaction outcomes using both stoichiometry and ligand-based control mechanisms will be demonstrated. 

Next, strategies to produce scalable quantum photonics platforms using colloidal QDs as single-photon emitters is an outstanding challenge in quantum information science. We will explore a method to exploit QD size to facilitate deterministic positioning of single QDs into large arrays while maintaining their photostability and single-photon emission properties. CdSe/CdS core/shell QDs encapsulated in silica results in an increase in their physical size without perturbing their quantum-confined emission. We demonstrate that these giant QDs can be precisely positioned into ordered arrays using template-assisted self-assembly with high yield for single QDs. We show that the QDs before and after assembly exhibit antibunching behavior at room temperature and their optical properties are retained after an extended period of time. 

Originally published at chemistry.nd.edu.

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