Untrafast Kinetics Of Electron Transfer From J-Aggregated To AgBrI Microcrystals Sensitized By Anionic-cationic Cyanine Dyes

In this paper, the fluorescence decay property of J-aggregates of anionic-cationic cyanine dye, anionic dye and cationic dye adsorbed on the surface of the cubic and tabular AgIBr grains is investigated using femtosecond up-conversion technology. The kinetics of the electron transfer and the spectral sensitization property in the dye sensitized system are detailed analyzed.By the measurement of the sensitization performance of several dyes, it is found that the sensitization performance of cubic AgBrI sensitized by anionic-cationic dyes are marked higher than that of anionic dye, cationic dye and the mixed of anionic dye and cationic dye. On the basis of the microwave absorption technology, it is showed that the photoelectron lifetimes of cubic AgBrI sensitized by anion-cation dyes is shortest, and the sensitization effect of anion-cation dyes is best. The fluorescence decay of J-aggregates on AgIBr grains obtained by femtosecond up-conversion is analyzed as a sum of two exponentials. And the fitting curves are consisted of a fast and a slow component. The average fluorescence decay lifetime of J-aggregates is shorter than that of dye monomer. Because of the large amplitudes, this fast decay should be mainly attributable to the electron transfer from J-aggregate of dye to conduction band of AgBrI. The electron transfer velocitie of J-aggregates of anionic-cationic dyes is larger than that of anionic dye, cationic dye and the mixed of anionic dye and cationic dye, which are consistent with the results of the sensitization performance and the photoelectron lifetimes. The sensitizing efficiency of anionic-cationic dyes for the tabular grains is higher than that for the cubic. Dye2 has higher sensitizing efficiency than Dye1 for both kinds of AgIBr grains.