LSM / IAMDN SEMINAR

LABORATORY FOR SURFACE MODIFICATION /

INSTITUTE FOR ADVANCED MATERIALS, DEVICES AND NANOTECHNOLOGY 

Thursday, March 30, 2017

12:00 PM, Room 260

Wright-Rieman Chemistry Laboratory

Lars Gundlach

Department of Physics

University of Delaware

"Ultrafast Probe of Charge Carrier Dynamics in Single Nanowires"

Ultrafast Charge Transfer Dynamics at Interfaces is a critical process in surface catalysis, novel electronic applications and solar energy conversion. The fast kinetics (below 100 fs) and the inhomogeneous environment complicate identifying the parameters that dominate the reaction. Transparent semiconducting nanostructured electrodes are of particular importance for these applications due to the large surface/volume ratio. Charge carrier diffusion and lifetime in these materials are the most important parameters for any electronic application. A novel femtosecond wide-field Kerr-gated UV luminescence microscope allows measuring charge carrier dynamics in single ZnO nanowires and enables calculating charge carrier motilities. Our work on single particle characterization is complemented by our synthesis of novel ZnO/CdSSe hierarchical tree-like nanostructure with CdSSe branches grown onto ZnO nanowire stems that are vertically-aligned on a substrate. The nanotrees show visible light absorption and give rise to a type II heterojunction at the interface between branch and stem. Ultrafast photoluminescence measurements indicate efficient electron transfer from CdSSe branches to ZnO stems after photoexcitation and suggest the possibility for Z-scheme charge transfer. The unique combination of optical, electronic, and structural properties indicates that the nanotrees are promising materials for applications that benefit from a Z-scheme charge transfer mechanism, for example in photo catalysis, opto-electronics, and chemical sensing.

Refreshments at 11:45 am

Courtesy of IAMDN 

Host: Frank Zimmermann