Nanoifbers Fabrication By Electrospinning And Applications In Dye Sensitized Solar Cells And Gas Sensors

Dye sensitized solar cells （DSSCs） has attracted intensive interestdue to its low cost, simplicity and high-efficiency. However, the energyconversion efficiency of the DSSCs is limited by the photoanodeperformance of TiO₂nanoparticles. The large amount of grain boundariesexisted in the titanium dioxide nanoparticles, which restrict electrontransmission. Electrospinning is a simple method of preparation ofcontinuous nanofibers. Nanofiber possesses features of excellentmechanical property, very high specific surface area, aspect ratios andporosity. In this paper, TiO₂and ZnO nanofibers were obtained viaelectrospinning and were used in DSSCs and gas sensors, respectively.The research content mainly includes the following three aspects:（1） TiO₂/PVP nanofibers were prepared by electrospinning.Influences of applied voltage, polymer concentration of solution,collecting distance and calcination temperature on morphologies werediscussed. With the concentration increase, the process of electrospinningneeded to overcome more surface tension because of increase of viscosity,and the diameters of electrospun fibers increased. With the increase ofapplied voltage, the diameters of electrospun fibers decreased. With theincrease of calcination temperature, the fibers became thiner. The increaseof deposition distance was favorable to obtain smooth nanofibers.（2） TiO₂/PVP nanofibers were prepared by electrospinning.Influencing factors on the electron transfer kinetics and thephotoelectrochemical properties of TiO₂based DSSCs were mainlydiscussed, including calcination temperature, surface treatments（acidification, oxygen plasma）, thickness of ZnO blocking layerfabricated by ALD method. It was demonstrated that TiO₂nanofibersobtained after550℃annealing showed the best photoelectrochemicalproperties. Acidification and oxygen plasma were favorable to improvethe photoelectric properties of TiO₂nanofibers. Using TiO₂nanofibers with5min oxygen plasma followed by acidification as photoanode, andusing15nm thickness of ZnO as a blocking layer, the TiO₂nanofiber cellhad the best perfomance.（3） ZnO/PVP nanofibers were prepared by electrospinning and usedin propanol gas sensing. It was found that the gas sensitivity increasedwith the gas concentration. When propanol concentration was800ppm,the sensitivity was23%. When the working temperature was400℃, thepropanol gas sensor showed good sensitivity.