| Summary: | 碩士 === 中原大學 === 化學研究所 === 102 === The studies of Dye-sensitized solar cells (DSSCs) often use the TiO2 nanoparticles (〜20 nm diameter) as the working electrode material, but the nanostructure limits transmission of the photoexcited electrons. Therefore, one-dimensional (1-D) nanostructure TiO2, materials have been used for the photoanode because of their effective pathways, facilitating the electron transport. In practice, even though an efficient electron transport rate in 1-D nanostructures is available, the performance of these 1-D TiO2-based DSSCs is still not good enough due to their smooth surfaces, leading to low surface areas and poor adhesion. Since high surface area is one of the key factors for improvement of the performance of DSSC, in this study, the 1-D backbone with a hierarchical nanostructure formed by the primary nanoparticles were prepared to enhance the surface area. The as-prepared 1-D hierarchical TiO2 nanotube not only significantly provided effective pathways for electron transport but also greatly increased the surface area, leading to a significant improvement in the power conversion efficiencies in DSSC.
In the study, a hierarchical anatase TiO2 nanotube (HTNT) has been synthesized via an electrospinning method followed by a hydrothermal process. It is found that the dense nanoparticles were grown on the HTNT. The materials with different morphologies were characterized by the SEM、XRD、TEM and BET measurements. The results indicated that the surface morphologies and surface area were varied with different structures. The result display the HTNT with superior crystalline phase, more dye loading, higher light scattering ability, faster electron transport, and greater charge collection efficiency. For application as the photoanode material of DSSC, the device fabricated with HTNT showed higher power conversion efficiency (6.36 %) than that with TNF, TNT, and P25. Besides, the significant improvement in DSSC efficiency was confirmed by the investigation of intensity modulated photocurrent spectroscopy (IMPS), intensity-modulated photovoltage spectroscopy (IMVS) and electrochemical impedance spectroscopy (EIS) measurements. In all, the HTNT prepared in this study exhibited the largest improvement performance of DSSC, hence, it is believed that HTNT nanofibers will be a high potential photoanode materials of DSSC.
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