Kuno Group


Greg Hartland: Transient absorption imaging of individual semiconductor nanowires


With Greg Hartland in the Department we are conducting transient absorption experiments on individual semiconductor nanowires.  These experiments enable us to image as well as resolve ultrafast carrier trapping dynamics into nanowire defect states.  Variable time constants are seen, which indicate intrawire heterogeneity in the energy and/or density of trap states.  These experiments ultimately aim to unravel the identity as well as behavior of defects in technologically relevant low dimensional materials.



Representative papers

Ultrafast dynamics distributions within an ensemble: Transient absorption microscopy studies of single CdTe nanowires, S. S. Lo, T. A. Major, N. Petchsang, L. Huang, M. Kuno, G. V. Hartland, ACS Nano, 2012, 6, 5274.

Imaging and absolute extinction cross section measurements of nanorods and nanowires through polarization modulation microscopy, C. R. Carey, T. Lebel*, D. Crisostomo*, J. Giblin, M. Kuno, G. V. Hartland, J. Phys. Chem. C. 2010, 114, 16029.

Experimental determination of single NW absorption cross-sections through photothermal imaging, J. P. Giblin, S. Mohammad*, M. T. Banning*, M. Kuno, G. V. Hartland, ACS Nano 2010, 4, 358.

Ultrafast transient absorption measurements of charge carrier dynamics in single II-VI nanowires, C. R. Carey, Y. Yu, M. Kuno, G. V. Hartland, J. Phys. Chem. C 2009, 113, 19077.

Prashant Kamat: Nanostructure sensitized solar cells


With Prashant Kamat we are developing third generation solar cells based on using nanostructures as sensitizers.  This work has previously led to the development of colloidal quantum dot solar cells and more recently nanowire-sensitized devices.  In tandem, we are pursuing ensemble kinetic studies using femtosecond transient differential absorption spectroscopy to elucidate the fate of photogenerated carriers in nanostructures given that this ultimately dictates device performance.



Representative papers

A CdSe nanowire/quantum dot hybrid architecture for improving solar cell performance, Y. Yu, P. V. Kamat, M. Kuno, Adv. Funct. Mater. 2010, 20, 1464.

Quantum dot solar cells: tuning the photoresponse through size and shape control of CdSe-TiO2 architecture, A. Kongkanad, K. Tvrdy, K. Takechi, M. Kuno, P. V. Kamat, J. Am. Chem. Soc. 2008, 130, 4007.

Size-dependent electron injection from excited CdSe quantum dots into TiO2 nanoparticles, I. Robel, M. Kuno, P. V. Kamat, J. Am. Chem. Soc. 2007, 129, 4136.

Quantum dot solar cells. Harvesting light energy with CdSe nanocrystals molecularly linked to mesoscopic TiO2 films, I. Robel, R. Subramanian, M. Kuno, P. V. Kamat, J. Am. Chem. Soc. 2006, 128, 2385.

Boldizsar Janko: Single nanostructure emission intermittency


With Boldizsar Janko in physics we are exploring the origin of single particle fluorescence intermittency.  This is a phenomenon ubiquitous at the single molecule level where the emission of individual molecules, fluorescent proteins, and quantum dots turns on and off in a seemingly random fashion.  Despite having been discovered over 15 years ago, no consensus exists today as to the actual physical mechanism behind “blinking”.  Our ultimate goal is to develop a microscopic picture that explains the unusual power law kinetics observed as well as the ubiquity of the phenomenon.



Representative papers

Electric field-induced emission enhancement and modulation in individual CdSe nanowires, F. Vietmeyer, T. Tchelidze, V. Tsou, B. Janko, M. Kuno, ACS Nano, 2012, 6, 9133.

Universal emission intermittency in quantum dots, nanorods and nanowires, P. Frantsuzov, M. Kuno, B. Janko, R. A. Marcus, Nature Physics 2008, 4, 519.

Galyna Krylova: Photocatalytic hydrogen generation using nanostructures


With Galyna Krylova we are developing new hybrid nanostructures that are photocatalytically active.  Of particular interest are systems that possess compositional complex stoichiometries as well as semiconductor/semiconductor or semiconductor/metal heterojunctions.  By tailoring band offsets between materials, we aim to achieve the efficient spatial separation of photogenerated carriers along with extensions of their lifetimes into a regime relevant for carrying out efficient chemical reduction/oxidation processes.


Representative papers

Photocatalytic hydrogen generation efficiencies in 1D CdSe heterostructures, P. Tongying, V. V. Plashnitsa, N. Petchsang, F. Vietmeyer, G. J. Ferraudi, G. Krylova, M. Kuno, J. Phys. Chem. Lett. 2012, 3, 3234.



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