Multilayer structures based on matrices of CdSe and CdSe/ZnS nanoparticles in polyimide (PI) and poly[2-methoxy-
5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) were prepared and investigated. A comparison of
photoluminescence of the various matrices excited by visible and ultraviolet laser radiation was carried out. The
main contribution to the photoluminescence was made by the organic semiconductors. Quantum yield of the
luminescence of CdSe nanoparticles embedded in organic semiconductor matrix was found to be lower then that of
the individual CdSe nanoparticles dispersed onto a glass substrate. This difference was shown to be a result of
charge transfer from the nanoparticles to organic molecules. The nanoparticles were responsible for photovoltage in
thin layers of the PI/nanoparticles composites. Processing of a surface of electrodes and organic semiconductors by
oxygen plasma increased the photovoltaic efficiency.
The films with low and high concentrations of CdSe/ZnS nanoparticles have been investigated under action of visible
and ultra-violet laser radiation in a wide range of power densities and temperatures. Strong shifts of absorption and
luminescence spectra without increase in their width have been observed at the transition from the solution to the films of
quantum dots. A complex investigation of anti-stokes luminescence of nanoparticles films has shown its thermal
mechanism. Luminescence spectra of the films of quantum dots under action of ultra-violet laser radiation allow
monitoring the presence of surface-active TOP and TOPO molecules in the films of quantum dots. The absence of
surface-active molecules in the films with high concentration of CdSe/ZnS nanoparticles is shown. The modes of the
action of power laser radiation on the films of quantum dots have been investigated. The possibility of controlling the
thickness of the films by laser ablation has been shown.
CdSe/ZnS quantum dots in solution ad in condensed phase have been investigated by methods of laser induced
luminescence. Anti-stokes photoluminescence (APL) of CdSe/ZnS nanoparticles in the solutions and in the films has
been studied under action of laser radiation of various wavelengths. The dependencies of APL of CdSe/ZnS
nanoparticles ensembles on exciting radiation intensity, temperature and quantum dots concentration have been studied.
It is shown that the mechanism of APL formation in CdSe/ZnS nanoparticles is thermal.
Optical properties of the films with high concentration of semiconductor core-shell CdSe/ZnS nanocrystals under
action of visible laser radiation in a wide range of power densities have been investigated. It's shown that in the films
with ultimate concentration ofthe nanocrystals a quantum-size effect is observed. High concentration of the nanocrystals
in the films and the presence of dipoles caused by nanoparticles asymmetry lead to strong shift of quantum-size peaks in
absorption and luminescence spectra compared to the solution and the films with low concentration of the nanoparticles.
The altitude of the shift depends on the thickness of the films and varies from 35 nm to 50 nm. The luminescence spectra
of the films don't change until the power density of exciting laser radiation exceeds 1x106 W/cm2. The regimes of laser
action on the films of the nanoparticles with power densities beyond the threshold of films destruction (from 5x106 W/cm2
to 1x109 W/cm2) have been investigated.