Our group is interested in the syntheses and study of electronic and optical properties of semiconductor nanocrystals and nanoscale assemblies of these particles. The interest in these quantum confined systems stem from the fact that these tiny fragments exhibit a wide range of properties that can be tuned by changing the size of the particles. For example, the emission properties can be tuned over the entire visible region. In certain cases, these tiny fragments are also known to show properties that are not observed in bulk materials.The ability to precisely control the composition, size and shape of the nanocrystals provides great flexibility in engineering their electronic and optical properties. Tunable dimensions and shapes of the individual particles as well as the ease of manipulating them into a complex interacting structure make colloidal nanocrystals well suited for studies of size- and structure-dependent quantum-mechanical interactions as well as ideal building blocks for nanoscale engineering. Understanding the mechanisms at work in these tiny particles can have very important implications in the areas of photovolatics, displays, biotagging and drug delivery, memory storage and optoelectronic devices. Fundamental research into the synthesis of these nanocrystals by various wet chemical routes, as well as studying and understanding the size dependent electronic, optical and magnetic properties of these materials will constitute the major research activity in this group.

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Synthesis of Novel Materials

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The major research thrust in this group is to harness the power of wet-chemical synthesis methods, to create novel materials that display unique physical properties. In nanoscale particles and composites, one can access a range of physical phenomena, such as quantum confinement or plasmonic effects, whose influences can be modified and balanced through choice of material(s) and careful control over particle size and shape. Colloidal syntheses have been shown to hold the promise for delivering the necessary size/shape control for an ever increasing range of metal, semiconductor and dielectric materials. Importantly, the product nanocrystals are usually dispersible, which renders them amenable to further reaction to create heterostructures of varied complexity, or to low-cost solution processing into composites or simple thin films for application, e.g. in optical devices.

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Another key advantage of colloidal synthesis is the flexibility to create unique material combinations that bring together multiple functionalities. One example of this is the creation of magneto-optical nanomaterials, in which magnetically-active species (either individual high-spin ions or nanosized metal domains) are incorporated directly into an optically active semiconductor nanostructure. The results are bifunctional materials that often display interesting interplay between the observable effects, ranging from simple magnetic switching of emission to tunable exchange interactions between semiconductor- and metal-based electronic states.

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Study of Electronic and Optical Properties

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Understanding the physics behind these novel properties allows us to identify and target particular materials, shapes and heterostructures that will produce desirable or simply unique properties and helps us to design, perform and interpret advanced spectroscopic probes of synthesized materials to observe the sought-after effects and elucidate the effects of small changes in structure. In this regard, our group is interested in performing the electronic structure calculations of these complex heterostructures as well as studying the optical and magnetic properties associated with these particles.