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Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 47: Quantum dots and wires: Optical properties II

HL 47.9: Vortrag

Freitag, 5. April 2019, 11:45–12:00, H34

Effect of Methyl Viologen on Electronic and Vibrational Spectra of Glutathione-stabilized Ag-In-S and Ag-In-S/ZnS Core-shell Quantum Dots — •Oleksandr Selyshchev1, Volodymyr Dzhagan1,2, and Dietrich R.T. Zahn11Semiconductor Physics, TU Chemnitz, Chemnitz D-09107, Germany — 2V. Lashkaryov Institute of Semiconductor Physics, Nat. Acad. Sci. of Ukraine, 03028 Kyiv, Ukraine

One of the challenges on the way to the application of colloidal quantum dots (QDs) in electronic devices, such as solar cells and field effect transistors, is their low electrical conductivity hindered by dielectric organic ligands. The idea of the current study is to modify the surface of colloidally synthesized QDs by another organic ligand, methyl viologen that possesses electron accepting properties and could act as an electrical linker. Here we investigate the effect of methyl viologen on the spectral characteristics of nonstoichiometric Ag-In-S and Ag-In-S/ZnS core-shell QDs stabilized by glutathione as the native ligand. Methyl viologen results in strong quenching of the QD photoluminescence (PL), while the QD absorption spectra remain without changes. This behaviour indicates photoinduced electron transfer from QDs (donor) to methyl viologen (acceptor). A decrease of the average lifetime of the PL additionally confirms the interaction via photo-excited states. Raman and FTIR spectroscopies show that glutathione ligands are still present on the QD surface, therefore the interaction of the methyl viologen (cations) with the QDs is realized via electrostatic bonding to negatively charged functional groups of glutathione.

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