Research

1. Interfacial Charge Transfer - Towards Efficient Solar Energy Conversion

The everlasting thrust for cost-effective alternative energy resources is one of the main interests of the group. The research efforts are focused on investigating the direct charge transfer excitations for applications in dye-sensitized solar cells. The fundamental aspects of the localization/delocalization of the charge transfer excitations are being investigated with ultrafast fluorescence and anisotropy measurements. New dye molecules with suitable charge transfer excitations are being synthesized and their excited state dynamics as well as solar cell efficiencies are being investigated. In addition, new donor-acceptor systems with charge transfer excitations for bulk heterojunction solar cells are under investigation.

2. Efficient Nonlinear Optical Materials

Nonlinear optical materials with enhanced cross-sections are being investigated especially in the context of their applications in multi-photon imaging and optical limiting. The idea is to apply the principles present in the field of dye-sensitized solar cells towards making better nonlinear optical materials. Here, the focus is on the dye molecules functionalized semiconductor nanoparticles as well as surface modified nanoparticles. Chromophore functionalized gold clusters are also being investigated for their two-photon absorption properties (collaboration with Prof Ekk Sinn).

3. Selective and Sensitive Optical Sensors

Nonlinear optical sensors with turn-off and turn-on two-photon excited fluorescence are being pursued. The main idea is to achieve stand-off detection with multi-photon sensing. Organic dye molecule based sensors are being investigated in the lab for metal ions, energetic materials and chemical warfare agents. Mechanistic aspects of the sensing are probed with time-resolved spectroscopic techniques.

4. Optical Properties of quantum-sized metal and semiconductor nanoclusters

          Time-resolved luminescence of quantum-sized gold clusters and semiconductor nanomaterials are being investigated with femtosecond fluorescence upconversion measurements. The studies provide unique aspects during the evolution of molecule to metal and molecule to semiconductor energy levels. Interesting fluorescence from quantum-sized gold clusters is observed which showed larger hot excited state lifetimes.

 

5. Ultrafast fluorescence dynamics of Proteins

            Intrinsic fluorescence of tyrosine is probed with femtosecond fluorescence upconversion to understand the structural aspects of protein folding in the Wilson’s disease protein (Collaboration with Prof David Huffman, WMU). Femtosecond fluorescence anisotropy measurements are being utilized to understand the auto fluorescence resonance energy transfer in fluorophore-labeled proteins.

Collaborators

Prof David Huffman – Department of Chemistry, WMU

Prof Ekkehard Sinn – Department of Chemistry, WMU

Prof Sherine Obare – Department of Chemistry, WMU

Prof Clement Burns- Department of Physics, WMU

Prof Dongil Lee - Yonsei University – S Korea

Prof Ronchao Jin - Carnegiel Mellon University - Pittsburgh

Dr Lingamallu Giribabu, Indian Institute of Chemical Technology, Hyderabad INDIA

Dr V. Jayatirtha Rao, Indian Institute of Chemical Technology, Hyderabad INDIA

Prof Valery Bliznyuk, WMU

Prof Muralidhar Ghantasala – Mechanical and Aeronautical Engg, WMU

Prof Tianshu Liu - Mechanical and Aeronautical Engg, WMU

Prof Gellert Mezei – Department of Chemistry, WMU

Prof Theodore Goodson III - University of Michigan,  Ann Arbor