Excited state dynamics of thin P3HT layers deposited on Au substrates of various morphology was investigated with the help of femtosecond Kerr-gated fluorescence microspectroscopy. The proximity of metal surface influences both radiative and nonradiative excited state decay processes, primarily through the coupling between the transition dipole and the collective motion of the electrons in the metal (plasmon), electric field effects and rapid electron exchange at the interface. We observed large acceleration of the radiative and nonradiative decay channels, as well as dynamic changes in the fluorescence spectrum of P3HT, which were found to depend on the structure of the metal surface and the thickness of the photoactive polymer layer (both characterized by SEM). In the case of some surfaces excited state lifetimes as short as 2 ps were observed and 400-fold enhancements of the radiative rate were deduced from the data. Such large enhancement effects are very important in the context of plasmonic solar cells, photocatalysis and optoelectronics.

Excited state dynamics of P3HT in close proximity to nanostructured metal surfaces.

246th National Meeting (2013)

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