| With the rapid development of industry, energy issues have become increasingly prominent, humanity urgently need a renewable energy instead of fossil fuels. Solar cells can convert solar energy to light directly without enviromental pollution in the process, thus they have attracted more and more people’s attention. In which, Sensitized solar cells have become research hotspots and focus because they have the advantages of simple preparation procedures, high photoelectric conversion efficiency and so on. Currently, organic dye as sensitizer have achieved highest efficiency, but due to it is so expensive and poor long-term stability that limits its application in the sensitized solar cells. The fluorescence quantum dots (QDs) have simple and cheap preparation method, the quantum confinement effect, large extinction coefficients, and good stability. Thus they become a photosensitive material to substitute for organic dye molecules.In this work, ZnSe and ZnSe:Mn QDs were synthesized in aqueous solutions. The morphology, crystalline structure, absorption spectra and emission spectra of the obtained samples were characterized by transmission electron microscopy (TEM), X-ray powder diffiaction (XRD), UV-Visible (UV-Vis) and fluorescence spectrometer, respectively. In addition, ZnO nanorod arrays were prepared by hydrothermal method. Quantum dots sensitised solar cells (QDSSC) based on ZnO nanorod arrays, and the resultant ZnSe and ZnSe:Mn nanocrystalline before the experiment as different sensitizers were assembled using the method of direct adsorption. The influence of ZnSe deposition time and deposition temperature, ZnSerMn deposition time and deposition temperature on the photoelectric performance of ZnO solar cell were discussed. The main research contents and conclusions were as follows:(1) Water-soluble ZnSe QDs were synthesized using SeO2as selenium source through one-step process. The effect of the type and amount of stabilizer, reaction time, Zn/Se molar ratio, pH of the original solution on the optical properties of ZnSe QDs were investigated. The obtained thioglycollic acid (TGA) capped ZnSe QDs had the best fluorescent properties, and the maximum quantum yield reached12.8%, with blue-green light-emitting region; The UV-Vis absorption peak showed blue shift to a certain extent with respect to the bulk materials; The ZnSe nanoparticles were approximately spherical with about3-4nm in size and cubic zinc blende crystal structure.(2) By using L-Cysteine as a stabilizer, white light-emitting Mn2+-doped ZnSe QDs were synthesized by a novel green preparation method in aqueous solution. The study found that the heating time, Mn2+concentrations, Zn/Se molar ratios, and initial pH value had a great impact on the photoluminescence properties of ZnSe:Mn QDs. At the optimized experimental conditions, the as-prepared ZnSe:Mn QDs belonged to the cubic structure with an average diameter of approximately4-5nm, and the UV absorption peak intensity greater than the undoped ZnSe QDs with the maximum fluorescence quantum yield of7.2%, the emit light of ZnSe:Mn QDs were located in the white area with CIE coordinates of (x=0.34, y=0.32).(3) ZnO nanorod arrays of regular morphology, optimal performance were prepared using hydrothermal method by optimizing the process conditions. QDSSCs were fabricated by covering the ZnO nanorod arrays with ZnSe and ZnSe:Mn QDs using direct adsorption method. The research indicated that when ZnSe deposition temperature and deposition time were5h and60℃, ZnO solar cells had the best photoelectric properties with conversion efficiency up to0.100%, short circuit current of1.392mA·cm-2, open circuit voltage of0.391V, fill factor of0.183. When the ZnSe:Mn deposition temperature and deposition time were3h and60℃, the photoelectric conversion efficiency of ZnO solar cell can reach a maximum value of0.280%, and the light current density was2.245mA·cm-2with open circuit voltage of0.670V, fill factor of0.182at this time. |
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