The Preparation Of Conjugated Polymers/Zinc Oxide With Optical And Electrical Properties Nano-composite Materials And Study On Their Photoluminescence Properties

Semiconductor nanocrystals have attracted much interest due to their electricaland optical properties. Nanoscale Zinc oxide(ZnO) is currently of potentialapplications as a functional inorganic material. Since it has many special mechanical,optical, electrical, magnetic, calorifics and chemical properties which differ from thecorresponding bulk materials due to its size effect, surface effect and quantum effect,as a wide band gap semiconductor material with large exiton binding energy of 60meV at room temperature, it is attractive for many new applications in industry andhigh-tech fields.In this thesis, electrospinning technique and photovoltaic device technique wereapplied to prepare polymer-ZnO nano-composite materials, and then the controllableUV luminescence of ZnO was performed. The details are as following:(1) On bases of the preparations of ZnO nanoparticles in references, a process ofdirect precipitation approach was established to synthesize ZnO nanoparticles and theeffects of various factors have been investigated. The appropriate process isconcluded. The product was characterized by XRD, TEM and TG-DTA, and theresults show that the product is single crystal type and of high purity. Most of theparticles are ball-shaped and are uniformly-distributed in diameter. The dispersibilityis excellent and the average particle size is less than 25nm.(2) Based on the synthesis of the ZnO nano particles, we report for the first timeon the synthesis of ZnO nanoparticles in conjugated polymer(PPV) nanofibers byelectrospinning and the coupling of the in situ and blend methods. These compositenanofibers were characterized by fluorescence microscopy, atomic force microscope(AFM), field emission scanning electron microscopy(FE-SEM), transmissionelectron microscopy(TEM), photoluminescence(PL) spectra, Fourier transforminfrared(FT-IR) spectroscopy, and X-ray powder diffraction(XRD). In ZnOnanoparticles/PPV composite nanofibers, ZnO nanoparticles were distributed uniformly without aggregation. In addition, the incorporation of ZnO nanoparticlesinto the conjugated polymer PPV strengthened the photoluminescence(PL) quantumefficiency of the PPV nanofibers. The band structure of the ZnO nanoparticles/PPVcomposite nanofibers should be in favor of photoexciton generation and radiation ofPPV. These composite nanofibers with excellent fluorescent property are potentiallyinteresting for many applications.(3) Since that the incorporation of ZnO nanoparticles into the conjugatedpolymer PPV strengthened the photoluminescence(PL) quantum efficiency of thePPV nanofibers, the ZnO nanoparticles which show perfect crystal character of thewurtzite ZnO were introduced into a new kind of polyfluorene copolymers, poly(2, 7-(9, 9-dioctyl-fluorene)-alt-5, 5-(4', 7'-di-2-thienyl-2', 1', 3',-benzothiadiazole)(PFDTBT),for more in-depth study of its thin film on the impact of photovoltaic devices wereprepared. This single-layer photovoltaic device performs a significant photovoltaicresponse(the best performed device is that containing 60 wt% of ZnO): photocurrentdensity of 1.17 mA/cm~2, open-circuit voltage of 0.81 V, fill factor of 0.09, andpower-conversion efficiency of 0.009%, which shows that polyfluorene derivative isexcellent fluorescence and photovoltaic material.One dimensional structure made from conjugated polymer/ZnO compositenanofibers were characterized by modern analysis and testing means(SEM, TEM, PL,etc.). The luminescence, surface photoelectric charge action, luminescence efficiencyand the effect of composite structure of nanofibers on the luminescent intensity wereinvestigated. These investigations not only enriched the synthesis methods forinorganic nanoparticles, but also provided a practical gist for synthesizing 1Dpolymer/inorganic composite nanomaterials. Consequently, practicality course ofpolymer nanomaterials were quicken.