Understanding Facet-dependent Exciton Dynamics in Strongly Confined Perovskite Quantum Dots

University Of Oklahoma Norman Campus, Norman OK

Investigators

Abstract

Nontechnical description Quantum light sources are essential for secure communications that utilize quantum information technologies. Colloidal halide perovskite nanocrystals are emerging as a new category of materials for cost-effective quantum light sources. To fully leverage this material in future quantum networks, it is crucial to understand and manage the light-emitting properties of these nanocrystals. Due to the small sizes of nanocrystals, their performance as controllable photon emitters greatly depends on the properties of exposed crystal facets. By employing synthetic methods that allow precise control over nanocrystal size and shape, along with facet-specific chemical defect passivation, this project will investigate the impact of the exposed crystal facets on the light-emission performance of colloidal halide perovskite nanocrystals. This project aims to enable more efficient and robust quantum emitters based on chemically synthesized nanocrystals. In addition to advanced materials science, the project includes educational activities designed to inspire students in interdisciplinary materials science and quantum technologies through hands-on experiments and the creation of new course materials. Technical description Colloidal lead halide perovskite nanocrystal quantum dots are promising candidates for quantum emitters due to their fast exciton radiative recombination rate and straightforward, scalable synthesis. However, the single-photon emission performance of individual perovskite quantum dots still requires improvements. Surface facets with different chemical identities can alter the morphology and defect properties of perovskite quantum dots, significantly impacting their exciton dynamics. Achieving precise control over facet exposure in strongly confined perovskite quantum dots and understanding the facet-dependent exciton dynamics is essential. This project aims to bridge this gap by developing facet-selective surface ligands to regulate the exposed crystal facets and aid in defect passivation. Specifically, this project will design organic ligand molecules with geometries that match the binding sites on different crystal planes, thus controlling the surface facets of perovskite quantum dots during colloidal synthesis. It will also investigate the exciton recombination dynamics at the single-particle level with facet-selective passivation. Additionally, the research team will explore the morphology-dependent multi-exciton recombination dynamics in perovskite quantum dots of varying sizes, thereby examining exciton-surface facet interactions. This project will analyze the role of surface facets and the morphology of lead halide perovskite quantum dots in influencing the recombination dynamics of single and multi-exciton states. Such insights are expected to advance the development of scalable quantum photonics for quantum communications. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.