Inorganic Materials and Spectroscopy
Primary Research Area
Other Area(s) of Interest
(Research Description PDF)
Our group is interested in the study of colloidal nanoscale inorganic semiconductor materials that are relevant for energy storage and transfer processes. These materials are particularly well-suited for applications that rely on the extraction of work, of one form or another, from electronically-excited states, such as photodetection, analytical sensing, solidstate lighting, photovoltaics, bio-imaging, or photocatalytic transformations, to name but a few. Semiconductor crystals that are limited to a few nanometers in scale — sometimes called "Quantum Dots" — also exhibit fascinating electro-optical properties that can be directly modulated by changing the size and/ or shape of the crystallite, allowing for precise tailoring of their physical behavior depending on the specific applications where they need to be used.
Our strategy is fundamentally interdisciplinary, and involves the development of materials synthesis and characterization methods, the use of a wide array of spectroscopic and electrochemical tools to understand the underlying physics that govern these novel materials, and the design of simple working devices to manipulate and optimize energy processes at the nanoscale.
Our efforts are directed along a few principal directions: • Design of new semiconductor nanomaterials, with special emphasis on group-III nitrides (AlxGayInzN, x + y + z = 1). The syntheses of these materials offer particular challenges that severely limit the development of applications based on this important class of materials. Our efforts are directed on optimizing solution-phase methods to yield high-quality colloidal nanomaterials, with a special emphasis on understanding the underlying chemical processes that govern the nucleation and growth of nitride nanocrystals.
• Charge storage processes at the nanoscale. Semiconductor nanostructures can accumulate large densities of electric carriers (electrons in the reduced state or holes in the oxidized state) without undergoing much structural changes, which contrasts with the behavior of isolated molecular species. Indium nitride is a particularly interesting example where charge accumulation occurs spontaneously, which is associated with intriguing new physics arising from the nonparabolicity of the conduction band dispersion.
• The structure and function of surfaces at the nanoscale. The surfaces of colloidal nanocrystals are characterized by a rather high level of structural and dynamic disorder. We are designing approaches aimed at unraveling the structural complexity of nanocrystalline surfaces in order to understand how specific surface defects modulate the properties of nanocrystals, including the study of non-radiative recombination processes that lead to energy losses in nanocrystal-based devices.
• Donor-Acceptor processes. We are generally interested in designing hybrid systems where energy and/or charge can be extracted from photoexcited semiconductor nanostructures and transferred to species that are bound to their surfaces. Such motifs are of particular relevance for the design of quantum dotsensitized solar cells (QD-SSCs), which are presently severely limited by energy losses due to the regeneration of oxidized semiconductor nanocrystals.
Insights into the Structural Complexity of Colloidal CdSe Nanocrystal Surfaces: Correlating the Efficiency of Non-Radiative Excited–State Processes to Specific Defects, Saniepay, M., Aldrich, E. P., Beaulac, R., J. Am. Chem. Soc. 2018, 140, 1725-1736.
On the Nature of the Infrared Transition of Colloidal Indium Nitride Nanocrystals: Non-Parabolicity Effects on the Plasmonic Behavior of Doped Semiconductor Nanomaterials, Liu, Z., Beaulac, R., Chem. Mater. 2017, 29, 7507-7514.
Solution-Liquid-Growth of Colloidal Indium Nitride Nanorods, Karan, N., Chen, Y., Liu, Z., Beaulac, R., Chem. Mater. 2016, 28, 5601-5605.
Photoluminescence Quenching of CdSe Quantum Dots by Nitroxide Free Radicals, Dutta, P., Beaulac, R., Chem. Mater. 2016, 28, 1076-1084.
Ph.D., 2006, Univ. de Montréal, Québec, Canada
B.A., 2001, Univ. de Montréal, Québec, Canada
NSERC Canada Graduate Scholarship, 2003-2005
Natural Sciences and Engineering Research Council Postdoctoral Fellowship, 2007-2009
Postdoctoral Fellow, 2006-2011, Univ. of Washington