Photoinitiated Electron Transfer Dynamics of a Terthiophene Carboxylate on Monodispersed Zinc Oxide Nanocrystals
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- 作者：Adam S. Huss ; Julia E. Rossini ; Darren J. Ceckanowicz ; Jon N. Bohnsack ; Kent R. Mann ; Wayne L. Gladfelter ; David A. Blank
- 刊名：Journal of Physical Chemistry C
- 出版年：2011
- 出版时间：January 13, 2011
- 年：2011
- 卷：115
- 期：1
- 页码：2-10
- 全文大小：450K
- 年卷期：v.115,no.1(January 13, 2011)
- ISSN：1932-7455
文摘
Photophysical data for solution phase mixtures of a new terthiophene based organic dye, 3鈥?4鈥?dibutyl-2-phenyl-2,2鈥?5鈥?2鈥测€?terthiophene-5鈥测€?carboxylic acid, and size selected, well-dispersed zinc oxide nanocrystals are reported. Time-resolved fluorescence and time- and frequency-resolved pump鈭抪robe spectroscopy confirm and characterize electron injection from the dye to the semiconductor nanocrystals (NCs) in room temperature ethanol dispersions at a series of dye:ZnO NC concentration ratios. The spectrum of the oxidized dye was determined by spectroelectrochemistry. The singlet excited state of the dye (190 ps lifetime in ethanol) is quenched almost exclusively by electron transfer to the ZnO NC, and the electron transfer dynamics exhibit a single time scale of 3.5 卤 0.5 ps at all concentration ratios. In the measured transient responses at different dye:ZnO NC ratios, gain in the amplitude of the electron injection component is anticorrelated with loss of amplitude from unperturbed excited state dye molecules. The dependence of this amplitude on dye:ZnO NC ratio deviates significantly from the prediction of a standard Stern鈭扸olmer model. This observation is in agreement with the static quenching studies presented in the companion manuscript (DOI: 10.1021/jp1080143). By identifying electron transfer as the quenching mechanism at all ratios, the work presented here helps to exclude concentration quenching as the basis for the complicated quenching results, and supports the model proposed in the companion work that incorporates competitive binding between ZnO NC s and free Zn2+ cations in solution.