Photoinduced relaxation processes in complexes based on semiconductor CdSe nanocrystals and organic molecules

Zenkevich, É. I.; Sagun, E. I.; Yarovoi, A. A.; Шульга, А. М.; Knyukshto, V. N.; Stupak, A. P.; Borczyskowski, C. von

doi:10.1134/s0030400x0712020x

Cited by 26 publications

(23 citation statements)

References 36 publications

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“…As seen, energy transfer does not play a dominant role in photoluminescence quenching processes in the given type of nanocrystals but provides direct evidence for the formation of stable NC-P nanocomposites. This conclusion agrees with the results of our investigations carried out for nanocrystals obtained from other sources [15,16,24]; inductive-resonance energy transfer NC ® P does not play a significant role in quenching of the luminescence in CdSe/ZnS nanocrystals. Accordingly the resonance energy transfer obtained from the sensitization experiments (see Fig.…”

Section: Resultssupporting

confidence: 95%

“…Our investigations [15,16,24] showed that the photoluminescence quenching in the nanocrystals during surface passivation by porphyrins depends weakly on the electron-donating and electron-accepting characteristics of the porphyrin ligand. Finally, we note that the quantum yield and life time of the fluorescence in the porphyrins P are practically unchanged compared with those measured for the individual porphyrins.…”

Section: Resultsmentioning

confidence: 97%

“…Since the photoluminescence in the investigated NC-P nanocomposites does not depend on the electronic nature of the porphyrin macrocycle [15,16,24] we will only consider those aspects of the interaction of the nanocrystal and porphyrin that can be related directly to interface effects on the surface of the nanocrystal and are determined by the dimensions of the CdSe core and the thickness of the ZnS shell. In our model, the general scheme of which is given in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…(TOPO) molecules (producer Evident Technologies Inc., Troy, NY, USA), amounted to~(3-7)·10 -7 M in unevacuated toluene (spectroscopic grade, Fluka SeccoSolv). The 5,10,15,20-tetra-meta-pyridylporphyrin (P) was synthesized and identified by the methods described in [32,33], and we investigated the detailed spectral characteristics earlier [15,16,22,24]. The initial concentrations of the individual ligand amounted to C P » 8·10 -6 -4·10 -5 M. The choice of the tetrapyridyl-substituted porphyrin ligand P for surface passivation of the nanocrystals was governed by the fact that for the multiporphyrin complexes [34] and for the NC-P nanocomposites [15,17,22] surface passivation of the nanocrystals with the organic component is possible on account of two-point bonding effects.…”

mentioning

confidence: 99%

“…The detailed experimental procedure for the formation of the NC-P composites with variable molecular composition x = C P /C NC was based on titration experiments and was set out in detail by ourselves in [15,16,22,24], where the employed apparatus and experimental errors are also described. In the case of interaction between the nanocrystals and P quenching of the photoluminescence of the nanocrystals was observed.…”

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confidence: 99%

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Effects of electron tunneling and nonresonance quenching of photoluminescence in semiconducting CdSe/ZnS AND CdSe nanocrystals by porphyrin molecules in joint complexes

et al. 2009

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The quenching of photoluminescence (PL) in semiconducting CdSe/ZnS and CdSe nanocrystals (NC) of various sizes during surface passivation by molecules of tetrapyridylporphyrins (P) in toluene at 295 K was investigated. It was shown that resonance transfer of energy NC ® P plays a minor role in PL quenching (<10%), while photoinduced electron transfer NC ® P is absent. On the basis of experimental data and quantum-mechanical calculations it was established that with identical molar ratio x = C P /C NC the probability of quenching k q decreases with increase in the size of the NC while the PL quenching process itself under conditions of quantum confinement is due to electron tunneling of the excited electron-hole pair on the surface of the NC followed by localization of the organic ligand (P) on anchor groups. The obtained results are of interest for investigating the mechanisms of the blinking of PL in single semiconductor nanocrystals.Despite the recently obtained results of scientific and applied interest [1-3], a series of problems concerning the luminescent characteristics and relaxation processes in nanocrystals (NC) during their interaction with various types of organic ligands still remain unsolved in the creation of novel effective composite materials based on a semiconducting nanocrystals and an organic molecule. Of special interest in this respect is the study of photoinduced charge transfer [4] and electronic excitation energy [5] in NC-organic ligand nanocomposites in so far as they form the basis of the various applications of these materials as optical markers in biological systems [6][7][8] or in the optimization of photovoltaic devices [9,10].At the present time various methods have been proposed and implemented for the creation of NC-organic ligand nanocomposites: Simple mixing [11]; substitution of the surface stabilizer molecules by the molecules of dyes [12]; the 0040-5760/09/4501-0023

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Section: Resultssupporting

confidence: 95%

Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Effects of electron tunneling and nonresonance quenching of photoluminescence in semiconducting CdSe/ZnS AND CdSe nanocrystals by porphyrin molecules in joint complexes

et al. 2009

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Combination therapy with rituximab and intravenous or oral fludarabine in the first‐line, systemic treatment of patients with extranodal marginal zone B‐cell lymphoma of the mucosa‐associated lymphoid tissue type

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et al. 2009

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Poly(3‐hexylthiophene)‐b‐poly(4‐vinylpyridine) diblock copolymer was synthesized by RAFT polymerization of 4‐vinyl pyridine using a trithiocarbonate‐terminated poly(3‐hexylthiophene) macro‐RAFT agent. The optoelectronic properties and the morphology of the block copolymer blends with CdSe quantum dots were investigated. UV‐vis and fluorescence experiments were performed to prove the charge transfer between CdSe and poly(3‐hexylthiophene)‐b‐poly(4‐vinylpyridine) diblock copolymer. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

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Formation Principles and Ligand Dynamics of Nanoassemblies of CdSe Quantum Dots and Functionalised Dye Molecules

et al. 2011

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Functional dye molecules, such as porphyrins, attached to CdSe quantum dots (QDs) through anchoring meso-pyridyl substituents, form quasi-stable nanoassemblies. This fact results in photoluminescence (PL) quenching of the QDs both due to Förster resonance energy transfer (FRET) and the formation of non-radiative surface states under conditions of quantum confinement (non-FRET). The formation process is in competition with the ligand dynamics. At least two timescales are found for the formation of the assemblies: 1) one faster than 60 s attributed to saturation of empty attachment sites and 2) one slower than 600 s, which is attributed to a reorganisation of the tri-n-octylphosphine oxide (TOPO) ligand shell. Finally, this process results in almost complete exchange of the TOPO shell by porphyrin dye molecules. Following a Stern-Volmer analysis, we established a microscopic description of PL quenching and assembly formation. Based on this formalism, we determined the equilibrium constant for assembly formation between QDs and the pyridyl-functionalised dye molecules to be K ≈ 10(5) - 10(7) M(-1), which is several orders of magnitude larger than that of the TOPO ligands. Our results give additional insights into the non-FRET PL quenching processes involved and show that the QD surface is inhomogeneous with respect to the involved attachment and detachment processes. In comparison with other methods, such as NMR spectroscopy, the advantage of our approach is that ligand dynamics can be investigated at extremely low ratios of dye molecules to QDs.

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Photoinduced relaxation processes in complexes based on semiconductor CdSe nanocrystals and organic molecules

Cited by 26 publications

References 36 publications

Effects of electron tunneling and nonresonance quenching of photoluminescence in semiconducting CdSe/ZnS AND CdSe nanocrystals by porphyrin molecules in joint complexes

Effects of electron tunneling and nonresonance quenching of photoluminescence in semiconducting CdSe/ZnS AND CdSe nanocrystals by porphyrin molecules in joint complexes

Combination therapy with rituximab and intravenous or oral fludarabine in the first‐line, systemic treatment of patients with extranodal marginal zone B‐cell lymphoma of the mucosa‐associated lymphoid tissue type

Formation Principles and Ligand Dynamics of Nanoassemblies of CdSe Quantum Dots and Functionalised Dye Molecules

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