Regensburg 2013 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 12: Poster Session II: Functionalized semiconductor nanowires (jointly with HL); Resistive switching (jointly with DF, KR, HL); Thermoelectric materials
DS 12.3: Poster
Montag, 11. März 2013, 17:00–20:00, Poster B1
Luminescence decay dynamics of colloidal CdSe quantum dots in different environments — •Michael Diez1, Stephanie Bley1, Dongchao Hou1, Sebastian Resch2, Siegfried Waldvogel2, Jürgen Gutowski1, and Tobias Voss1 — 1Institute of Solid State Physics, Semiconductor Optics, University of Bremen, 28359 Bremen, Germany — 2Institute of Organic Chemistry, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
The functionalization of semiconductor surfaces with colloidal quantum dots has gained substantial interest because of its wide application in optical sensing and energy harvesting. The quantum dots can be selectively attached to semiconductor surfaces with the help of linker molecules. We have studied the luminescence decay dynamics of colloidal CdSe quantum dots functionalized with ω-mercapto alkanoic acid in different environments. As optical excitation source we use a frequency-doubled Ti:sapphire laser (λ=350 nm, Δ t=60 fs, f=82 MHz and Epulse=12 nJ). We detect the luminescence signal with a streak camera and an attached spectrometer (Δ t<2 ps, Δ λ <0.2 nm). For colloidal CdSe quantum dots in aqueous solution, we find that the luminsescence decay time can be well fitted with a biexponential decay (shorter decay time t1≈ 200 ps, longer decay time t2 ≈ 3 ns). Furthermore, we discuss the importance of surface and bulk states for the observed biexponential decay and study the change of t1 and t2 for quantum dots attached to different oxide surfaces. The observed results will allow for the optimization of quantum dot properties for specific optoelectronic applications.