Laboratory for Femtosecond Spectroscopy
The Laboratory for Femtosecond Spectroscopy uses a variety of techniques to conduct cutting edge experiments to answer key questions in chemistry and photo-physics.
We use steady state and time-resolved spectroscopic techniques to investigate the molecular processes in two significant systems.
Our system of interest is the highly fluorescent conjugated polymer nanostructures. We currently focus on using femtosecond transient absorption spectroscopy and fluorescence upconversion spectroscopy to understand the effect of the shape of the nanostructure on the energy and charge transfer processes in these structures. Because conjugated polymers are used as organic solar cell materials, a good understanding of these processes will lead to strategies for improving the efficiency of organic solar cells.
Another system of interest is molecules that undergo singlet fission. Our work aims to understand the mechanism of singlet fission by controlling the intermolecular distance and orientation of the pair of molecules that are involved in singlet fission.
Conjugated polymer materials
High-energy excited states
The high-energy excited states of conjugated polymers are associated with the photovoltaic properties of these materials. We use pump-push-probe spectroscopy to investigate the crossing between these high-energy states with the charge-transfer state to further understand the charge separation process of conjugated polymer materials.
Organic light emitting diodes
We use aqueous dispersions of conjugated polymers (conjugated polymer nanoparticles) to fabricate organic light emitting diodes. Characterisation of these diodes to understand their electroluminescence efficiencies and modelling of the underlying exciton annihilation processes are under way.
We use surface functionalisation to enable colloidal stability and potential for bioconjugation of conjugated polymer nanoparticles. We are characterising these materials to understand their luminescence efficiencies, cytotoxicity and internalisation by cells.
Multidimensional optical spectroscopy
We are building a new two-dimensional electronic spectrometer that has an accuracy of 28 as. This spectrometer uses femtosecond laser pulses in the visible region generated using a noncollinear optical parametric amplifier.
Coherences in artificial light-harvesting systems
In the near future, we will use our two-dimensional electronic spectrometer to study coherent processes in synthetic light-harvesting systems including conjugated polymers and gold nanorods.
Generation of two triplet excited states by splitting one singlet excited state
We use femtosecond pump-probe spectroscopy to elucidate the mechanism of singlet fission. In particular, we develop novel methods of controlling the intermolecular distance and orientation of the pair of molecules involved in singlet fission.
Conjugated polymer nanostructures
- David M. Huang, Department of Chemistry, University of Adelaide, Australia
- Stephen F. Lincoln, Department of Chemistry, University of Adelaide, Australia