Journal
ACS NANO
Volume 9, Issue 3, Pages 2886-2903Publisher
AMER CHEMICAL SOC
DOI: 10.1021/nn506941c
Keywords
quantum dot/dye nanoassemblies; photoluminescence intermittency; single quantum dots; spectral diffusion; photoluminescence decay; CdSe/ZnS; photoluminescence spectra; pyridyl-substituted porphyrins; temperature dependence; ligands
Categories
Funding
- DFG Priority Unit [FOR 877]
- Belarussian State Program for Scientific Research Convergence 3.2.08-Photophysics of Bioconjugates, Semiconductor and Metallic Nanostructures and Supramolecular Complexes and Their Biomedical Applications
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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 290K. This includes a kind of phase transition of trioctylphosphine oxide I igands, 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 ligancl-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.
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