Master of Science (M.Sc.)
The impact of molecular aggregation on the photophysics of eosin y adsorbed to TiO2 was investigated using diffuse reflectance spectroscopy, steady-state fluorescence and time correlated single photon counting (TCSPC) measurements. Deconvolution of the diffuse reflectance spectra of eosin y on TiO2 revealed the formation of H-aggregates, with the extent of H-aggregation increasing with increasing dye-loading concentration. The resultant bathochromic shift from the monomer diffuse reflectance maximum is due to Charge-transfermediated H-aggregates The fluorescent maximum also shifts with increasing dye loading concentration starting at 537.5 nm at a dye loading concentration of 7.5x10-7 M and shifting to 585 nm at a dye loading concentration of 10-3 M. The fluorescent lifetime of eosin y in acetonitrile was measured to be 3.62 ns at 5x10-7 M. The fluorescent lifetime of EY/TiO2 was measured to be 0.38 ns and EY/ZrO2 was measured to be 1.47 ns at 5x10-7 M. The fluorescent lifetime of EY/TiO2 is significantly shorter that eosin y in both solution and on ZrO2 which is consistent with quenching from electronic injection. Furthermore, the lifetime of EY/ZrO2 was quenched from 1.47 ns to 0.39 ns at dye loading concentration of 1x10-5 M consistent with increasing H-aggregation. Showing that for eosin y aggregation is hampering electronic injection.
© The Author
Richards, Huw, "Unravelling The Aggregation Of Eosin Y Photosensitisers For Solar Energy Conversion" (2020). Dissertations, Theses, and Masters Projects. William & Mary. Paper 1593091538.