|Stage I||Investigation of the radiative recombination of excitons in PPV films.
i) The chemical synthesis of the precursor of PPV;
ii) The revelation of the modifications induced in the photoluminescence spectra of PPV films by temperature, thickness of the polymer films and the thermal conversion regime of the precursor .
|Stage II||Investigation of the photoconducting properties of the PPV/NTC and PPV/TiO2 composites under steady state regime.
i) Preparation of micronic and nanometric TiO2 particles;
ii) the evidence of the percolating character of the photoconduction process in PPV/NTC type composites;
iii) the establishment of the kinetics of the photocurrent decay upon the cessation of the optical excitation;
iv) the evidence of a process of charge transfer in the PPV/TiO2 composite.
investigation of the particularities of the radiative recombination
processes in PPV/NTC and PPV/NPO type composites by means of
photoluminescence measurements performed under continuous excitation.
i) The evidence of the changes induced in the PL spectra of PPV as result of the presence in the polymer matrix of the carbon nanotubes and oxide nanoparticles (NPO: SiO2 and TiO2) ;
ii) Assignation of the particularities of directionality of the PL emission;
iii) the charge transfer is main operating mechanism that governs the interaction between polymer and carbon nanotubes.
|Stage IV||The investigation of the PL properties of the PPV/NPO composites under high density of optical excitation.
i) the evidence of the particularly spectral, transient and directional luminescent emission of the composites based on PPV and NPO (SiO2 and TiO2) at high density of excitation;
ii) evidences for a laser emission.
|Stage V||Investigation by transient optical spectroscopy of the dynamics of the excited states in the PPV/CNs and PPV/NPO composites
i) the study of the excitons dynamic in composites of the type PPV/CNs and PPV/NPO; the evaluation of the PL quencing constant;
ii) the study of the changes induce in the kinetic of radiative recombination process of CNs and NPO ((SiO2 and TiO2);
iii) evaluation of the concurent non-radiative mechanisms of quencing of excitation state in composite films.