Dresden 2006 – scientific programme
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HL: Halbleiterphysik
HL 50: Poster II
HL 50.90: Poster
Thursday, March 30, 2006, 16:30–19:00, P3
Energy transfer processes in ensembles of CdSe quantum dots of different sizes — •M. Rohe1, M. Grau1, P.J. Klar1, W. Heimbrodt1, M. Yosef2, and S. Schlecht2 — 1Dept. Physics and WZMW, Philipps-University of Marburg, Germany — 2Institute of Chemistry and Biochemistry, FU Berlin, Germany
Bimodal random ensembles of CdSe quantum dots containing two distinct sizes (e.g. 3 nm and 9 nm) and mixed different ratios were studied by cw and time-resolved photoluminescence (PL) techniques. Due to different quantum confinement situations in the two subsystems of dots, the corresponding PL spectra show two spectrally resolved bands of which the high-energy band corresponds to the 3 nm dots whereas the low-energy band corresponds to the 9 nm dots. A coupling between the two subsystems of dots is revealed by time-resolved PL where the decay time of the 9 nm dots is significantly increased in the presence of 3 nm dots compared to an ensemble of solely 9 nm dots. This demonstrates that, in addition to energy transfer processes within each of the two subsystems, an energy transfer takes place from the 3 nm dots to the 9 nm dots. We study these energy transfer processes in dependence on the mixing ratios.