Energy Transfer via Exciton Transport in Quantum Dot Based Self-Assembled Fractal Structures

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• 作者：C茅sar Bernardo ; I. Moura ; Y. N煤nez Fern谩ndez ; Eduardo J. Nunes-Pereira ; Paulo J. G. Coutinho ; Arlindo M. Fontes Garcia ; Peter Schellenberg ; Michael Belsley ; Manuel F. Costa ; Tobias Stauber ; Mikhail I. Vasilevskiy
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：March 6, 2014
• 年：2014
• 卷：118
• 期：9
• 页码：4982-4990
• 全文大小：522K
• 年卷期：v.118,no.9(March 6, 2014)
• ISSN：1932-7455

文摘

Semiconductor quantum dot (QD) assemblies are promising systems for light harvesting and energy conversion and transfer, as they have a superior photostability compared to classical dyes and their absorption and emission properties can be tuned during synthesis. Here, we investigate excitonic energy transfer in self-assembled dentrite-type fractal structures consisting of QDs by microscopically mapping their fluorescence spectra and lifetimes. The behaviors of CdSe/ZnS and CdTe QD assemblies are compared; in particular, the energy transfer probability is found to be stronger in CdTe-based structures, scaling with their radiation quantum yield. Our results indicate F枚rster-type energy transfer in both systems, although with a higher efficiency in CdTe. The energy transfer is caused by near-field (nonradiative) dipole鈥揹ipole coupling between the individual QDs within a dendrite, with the excitation migrating from the edges to the center of the structure. The experimental findings are supported by theoretical modeling results obtained by using master equations for exciton migration/decay kinetics in diffusion-limited fractal aggregates composed of identical particles.