Description
Date/Time: 04-05-2018 - Thursday - 05:00 PM - 07:00 PM
Kaifu Bian1 Binsong Li1 Ting Shan Luk1 Igal Brener1 Michael Sinclair1 Zhongwu Wang2 Hongyou Fan1

1, Sandia National Laboratories, Albuquerque, New Mexico, United States
2, Cornell University, Ithaca, New York, United States

Quantum dots are promising building blocks for important applications including photovoltaic, light emission, transistors and bioimaging due to their unique size- and shape-dependent optical and electronic properties. The ability to tune optical and electronic properties of quantum dots by engineering their size, shape, and composition has proved to be a versatile way to interrogate structure–property relationships in quantum dots. Here we present a new method to engineer quantum dot assemblies and to probe their structure-property relationships through stress-induced phase transformation and their exchange coupling during high-pressure compression. We show that under hydrostatic pressure, the unit cell dimension of a 3-dimensional (D) ordered quantum dot superlattice can be manipulated to shrink and swell reversibly, allowing fine-tuning of interparticle separation to probe optical coupling in the supertlattice. Further, beyond a threshold pressure, quantum dots are forced to connect with neighboring dots to form new classes of chemically and mechanically stable 1-3D nanostructures including nanorods, nanowires, nanosheets, and nanoporous networks which cannot be achieved by traditional top-down or bottom-up methods. Moreover, through in situ high-pressure synchrotron-based x-ray scatterings and optical absorption measurements, we discovered Hall-Petch-like size-dependent elastic stiffness and size-dependent pressure coefficient of energy gap in quantum dots. Stress-induced phase transformation and exchange coupling provides new insights for fundamental understanding of chemical and physical properties of quantum dots.

Meeting Program
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5:00 PM–7:00 PM Apr 5, 2018

PCC North, 300 Level, Exhibit Hall C-E