Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 9: Poster 1

HL 9.104: Poster

Montag, 23. März 2009, 14:30–17:00, P2

Energy Dynamics in Polymer-Coated Quantum Dots with Integrated Dye Molecules — •Tobias Niebling, Ali Zulqurnain, Feng Zhang, Wolfram Heimbrodt, and Wolfgang J. Parak — Department of Physics and Material Sciences Center, Philipps University Marburg, Germany

Semiconductor nano-particles have emerged as promising candidates for the basis of sensors in bioanalytics and markers for biolabeling. Inorganic CdSe quantum dots are coated with amphiphilic polymers in order to transfer them to aqueous solutions. Additionally, it is possible to embed ATTO-dye molecules in the polymer shell. The spectral overlap between the emission of the nano-particles and the absorption of the dye molecules can be modified by choosing different sizes of the quantum dots. Continuous-wave measurements as well as time-resolved photoluminescence measurements show that the emission properties of the quantum dot-dye molecule system are dominated by energy transfer processes. The presence of the quantum dots decelerates the decay of the dye emission, due to (i) re-absorption of photons emitted by the nano-particles and (ii) non-radiative energy transfer. The latter becomes more important the smaller the distance between the nano-particles and the dye molecules and the larger the spectral overlap between quantum dot emission and dye absorption. The measurements can be described within a model that accounts for the interplay of the excitation dynamics of the quantum dot and the dye molecules with respect to the different transfer processes.