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Semiconductor nanoshell quantum dots for energy conversion application

Mikhail Zamkov,

Bowling Green State University

Colloidal semiconductor quantum dots have attracted a great deal of attention in recent decades due to their remarkable optical and electronic properties. Many applications of these nanomaterials have been proposed for the energy sector technologies. However, their practical realization still faces fundamental challenges. One of the reasons for the slow implementation of quantum dots in device technologies concerns a sharp decline in their performance efficiency resulting from a large amount of energy being introduced within a small-size nanoparticle. This issue represents one of the main performance-limiting factors in a broad spectrum of quantum dot applications, including photodetectors/X-ray scintillators, photovoltaic devices, and high-brightness LEDs. The present project will address this issue by developing two-dimensional semiconductor quantum shells, which geometry is designed to sustain energetic loads more efficiently than quantum dots. By enabling an optimal distribution of the excitation energy across the nanostructure, quantum shells effectively prevent the primary mechanism of energy losses – Auger recombination. The advantages of quantum shells over quantum dots will be demonstrated using a three-prone research strategy, including synthetic innovation, spectroscopic measurements of optoelectronic characteristics, and device fabrication. As part of this effort, quantum shells will be explored in applications that have previously faced substantial energy losses due to Auger recombination in quantum dots. These include X-ray scintillators, photovoltaic devices, quantum light sources, and high-brightness LEDs. Several types of semiconductor materials will be investigated toward expanding the spectral range of the quantum shell optical response.

            The successful development of quantum shells will result in a novel class of colloidal nanomaterials for solution-processing of semiconductor devices. Auger recombination is an obstacle to most applications of low-dimensional nanostructures and the ability to address this issue will likely yield advances across different energy disciplines. From the broader prospective, quantum shells could emerge as an alternative to existing low-dimensional colloids (quantum dots, nanosheets, nanotubes, nanorods, etc.) both by supporting high energy density and by offering a greater potential for the assembly into ordered, electrically-coupled nanoparticle solids. Ultimately, the concept of quantum shells can be applied to non-toxic and abundant semiconductor systems to be deployed in “printable” nanostructured materials. As an integral part of this project, the PI will lead a multi-faceted educational effort focusing on student training and public outreach.