Photonic and Light Harvesting Materials

1) Dipolar Materials - we design, synthesize, and study using ultrafast tranisent absorption spectroscopy, several new classes of small molecules consisting of D-A, A-D-A, and D-A-A with large ground state dipole moments. The conjugated heterocycles can be tailored with branching, end-group and chain-length functionalization with tunable HOMO-LUMO energy levels for 3rd generation solar energy technologies. We have investigated liquid crystalline polymorphs of dipolar, D-A-A materials through combined ultrafast spectroscopy and polarized light microscopy. This work is highlighted in our recent publication in Physical Chemistry Chemical Physics.

2) Pb-free perovskites - we synthesize and study ultrafast exciton and charge carrier dynamics of single crystal and thin films of organic-inorganic perovskites as new light harvesting materials.

Natural Chromophores for Ultrafast Imaging

Small molecule metabolites, cofactors, and vitamins play critical roles in cell function, and because of their intrinsic size, they cannot be labeled and are virtually undetectable using traditional fluorescence microscopy. However, flavin cofactors can serve as natural imaging chromophores in their ground state because they are light sensitive redox active molecules with large ground state absorptions of the aromatic core centered at 400 nm. Here, we utilize ultrafast transient absorption to study a quinacrine (Qc) and riboflavin small molecules as antagonist for riboflavin receptor binding (RfBP) in aqueous solutions through detection of the photogenerated radical pair that persists on the picosecond timescales. Thus, the system studied here will be utilized in time-resolved imaging of small molecule-proteins composed of natural chromophores using femtosecond lasers in a time and spatially-resolved imaging platform complementary to fluorescence and FRET microscopy.

Competitive Charge and Energy Transfer in Hybrid Materials for Biosensing and Bioimaging

We investigate how excited state interactions between CdSe-ZnS quantum dots (QDs) or organic donor molecules, linked to redox-active chromophores, compete between Förster Resonance Energy Transfer (FRET) and charge transfer (CT) reactions for biosensing and bioimaging. Several collaborations are currenting ongoing between the Scott group and researchers at the University of Miami, Florida State University, and the Naval Research Laboratory.