title: Tuning electronic states of a CdSe/ZnS quantum dot by only one functional dye molecule.
abstract: Self-assembly of only one functionalized porphyrin dye molecule with one CdSe/ZnS quantum dot (QD) not only modifies the photoluminescence (PL) intensity but also creates a few energetically clearly distinguishable electronic states, opening additional effective relaxation pathways. The related energy modifications are in the range of 10-30 meV and show a pronounced sensitivity to the specific nature of the respective dye. We assign the emerging energies to surface states. Time-resolved PL spectroscopy in combination with spectral deconvolution reveals that surface properties of QDs are a complex interplay of the nature of the dye molecule and the topography of the ligand layer across a temperature range from 77 to 290 K. This includes a kind of phase transition of trioctylphosphine oxide ligands, switching the nature of surface states observed below and above the phase transition temperature. Most importantly, our findings can be closely related to recent calculations of ligand-induced modifications of surface states of QDs. The identification of the optical properties emerged from a combination of spectroscopy on single QDs and QDs in an ensemble.
authors.affiliation: †Department of Information Technologies and Robotics, National Technical University of Belarus, Nezavisimosti Ave., 65, 220013 Minsk, Belarus.
authors.forename: Eduard
authors.initials: E
authors.lastname: Zenkevich
authors.affiliation: ‡B.I. Stepanov Institute of Physics, National Academy of Science of Belarus, Nezavisimosti Ave., 70, 220072 Minsk, Belarus.
authors.forename: Aleksander
authors.initials: A
authors.lastname: Stupak
authors.affiliation: §Institute of Physics, Technische Universität Chemnitz, Reichenhainerstr. 70, 09107 Chemnitz, Germany.
authors.forename: Clemens
authors.initials: C
authors.lastname: Göhler
authors.affiliation: §Institute of Physics, Technische Universität Chemnitz, Reichenhainerstr. 70, 09107 Chemnitz, Germany.
authors.forename: Cornelius
authors.initials: C
authors.lastname: Krasselt
authors.affiliation: §Institute of Physics, Technische Universität Chemnitz, Reichenhainerstr. 70, 09107 Chemnitz, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: von Borczyskowski
keywords: CdSe/ZnS; ligands; photoluminescence decay; photoluminescence intermittency; photoluminescence spectra; pyridyl-substituted porphyrins; quantum dot/dye nanoassemblies; single quantum dots; spectral diffusion; temperature dependence