Photoinduced dissociation of surface complexes of CdSe/ZnS quantum dots with azo-dye 1-(2-
pyridylazo)-2-naphthol (PAN) was investigated. It was shown that the Förster resonance energy transfer contributes in
the complexes photodissociation rate, which depends on resonance condition between electronic levels of donor
(quantum dots) and acceptor (azo-dye) and donor photoluminescent quantum yield. It has allowed to estimate energy
transfer efficiency in the complexes and disclosed a new nonradiative channel that has minor contribution in the
deactivation of excited states of quantum dots in the complexes.
Photoinduced changes in luminescent and photoelectrical properties of the hybrid structure based on CdSe/ZnS QDs and
multilayer graphene nanobelts were studied. It was shown that an irradiation of the structures by 365 nm mercury line in
doses up to 23 J led to growth of QD luminescent quantum yield and photocurrent in the QD/graphene structures. This
confirms the proximity of the rates of the QD luminescence decay and energy/charge transfer from QDs to graphene, and
opens an opportunity to photoinduced control of the photoelectric response of the graphene based hybrid structures with
semiconductor quantum dots.
We present technique of obtaining complex hybrid structures combining the multi-walled carbon
nanotubes or multi-layer graphene and luminescent hydrophobic semiconductor core/shell quantum dots
CdSe/ZnS. As a result, a formation of quantum dot decorated carbon nanotubes and graphene films is evidenced
by 2D microluminescence and micro-Raman mapping of quantum dots and nanocarbons, respectively, where a
spatial correlation between the luminescence and Raman signals is found.
KEYWORDS: Semiconductors, Data modeling, Luminescence, Molecules, Energy transfer, Quantum dots, Resonance energy transfer, Fluorescence resonance energy transfer, Positron emission tomography, Molecular energy transfer
Hybrid structures based on CdSe/ZnS quantum dots and porphyrin molecules with effective energy transfer were formed in samples of polymer track pore membrane. It was observed that energy transfer efficiency depends on quantum dot size and correlates with overlapping integral between quantum dot photoluminescence and porphyrin absorption spectra inherent for Förster Resonant Energy Transfer, FRET. However, a noticeable deviation of experimental FRET efficiency dependence on an acceptor concentration from theoretical ones was observed for all donor-acceptor pairs. A gradient of donor and acceptor concentrations in the matrix is considered as the most probable reason of this deviation. A theoretical model describing energy transfer in a rigid solution with a gradient of particle concentration is proposed.
In present study complexes between non-toxic ZnSe/ZnS quantum dots and chlorin e6 molecules that are widely used as photosensitizers in photodynamic therapy were formed. It was found that in aqueous solution cationic ZnSe/ZnS quantum dots and chlorin e6 formed stable complexes that exhibit efficient photoexcitation energy transfer from quantum dots to molecules. Spectroscopic methods were applied to evaluate the energy transfer efficiency. Stoichiometry of these complexes was studied. Additionally, the photodynamic therapy efficacy of the quantum dotchlorin e6 complexes was in vitro assessed against Ehrlich ascites carcinoma cancer cell line using a trypan blue assay. We found that complex offered an improved cancer cell photodynamic destruction effect as compared to that of free chlorin e6.
We investigate electrical photoresponse of multilayer graphene decorated with CdSe/ZnS quantum dots. It was found that photoresponse of these hybrid structures depends on quantum dot photoluminescence quantum yield. We demonstrate in uence of external factors (light exposure and treatment with ammonia vapors) on photoluminescence quantum yield of quantum dots and electrical photoresponse of the hybrid structures.