Synthesis And Photovoltaic Performance Of Nanocrystalline TiO₂based Hybrid Structures

Severe energy shortage is one of the most serious challenges facing mankind thathas attracted increasing attentions. Recently, solar energy has emerged as the the oneof effective substitutions of traditional energy, because it is an inexhaustible andenvironmentally friendly source. Dye-sensitized solar cells （DSSCs） based onnanocrystalline TiO₂have been developed as commercially compelling alternative forthe Si based solar cells due to its lower manufacturing cost and high photoelectricconversion efficiency （）. In this dissertation, the effects of paste preparation processon the photoelectric properties of TiO₂nanocrystalline DSSCs were discussed; theeffects of ZnO mass percentage on the photoelectric properties of TiO₂/ZnOcomposite nanocrystalline DSSCs were studied; and TiO₂/ZnO micron/nano structure,as well as TiO₂nanofibers and hollow nanofibers were fabricated by electrosprayingand electrospinning, respectively. The main contents of this dissertation aresummarized as follows:1) The effects of paste preparation process on the photoelectric properties ofTiO₂nanocrystalline DSSCs were studied. The results showed that during thepreparation process of TiO₂paste, the acetylacetone, deionized water, and Triton X-100should be added drop wise in turn, and the grinding time should be kept20min for eachadditives, which will produce porous and loose photoanodes, resulting inphotoelectric conversion efficiency （） up to8.30%.2) TiO₂/ZnO composite films with different ZnO concentration were prepared bydoctor-blade method. The correlations between the concentration of ZnO andphotovolatic performance of the TiO₂/ZnO DSSCs were investigated. The resultsshowed that the highest photoelectric conversion efficiency was obtained when themass percentage of ZnO was2%（2TZ）, and the corresponding photocurrent densityand photoelectric conversion efficiency were18.11mA·cm-2and9.53%, respectively.The results of scanning electron microscopy （SEM） confirmed their larger surfacearea and higher porosity. UV-vis absorption spectra （UV-vis） results showed that the dye-loading absorption increases with increased ZnO mass percentage, whichexplains the enhanced conversion efficiency.3) Electrospraying and electrosprinning methods were used to synthesize TiO₂materials of different micron or nano structures, and the effects of the processingparameters on the morphology of TiO₂/ZnO composite spheres and TiO₂hollow fiberswere studied. Balls with regular micro/nano structure were fabricated on conductivegalsses by electrospraying. TiO₂fibers also were synthesized by eletrospinning, andthe photovoltaic performance of DSSCs made of TiO₂fiber was researched. Coaxialand single axial electrosprinning methods were introduced to fabricate TiO₂hollowfibers. And our results showed that TiO₂fibers are zebraic or solid structure whenprepared by coaxial electrospinning method, which indicate the modification ofsynthesis parameters. However, those fibers prepared by single axial electrospinningwere hollow.The dissertation provided some basic experimental guideline for theimprovement of photovolatic performance in DSSCs.