Optimized Preparation And Photoelectric Performance Evaluation Of TiO₂ Nanotubes Photoanode

Dye sensitized solar cells have been regarded as a potential alternative to the traditional silicon solar cells because of their several advantages,such as high efficiency and low-cost,which still attract people's attention to date.After 20 years of sustainable development,the demand for their practical application has become increasingly an urgent issue needed to be tackled.TiO₂ nanotube arrays serve an important multifunctional nanometer material,which exhibits broadly valuable applications in many fields,such as photocatalytic,gas sensor,optical materials and dye sensitized solar cells.Aiming at the exploitation of TiO₂ nanotube arrays as the photoanode of dye sensitized solar cells,our great energies are devoted to study the high-efficiency,stable,low-cost and practicability of dye sensitized solar cells based on the corresponding photoanode.The main contents of research are presented as follows:1.The fabrication of doubly open-ended TiO₂ nanotube arrays:unlike using highly secondary anodic voltage?150 V?to opening the bottom of TiO₂ nanotube arrays and their detachment from the Ti foil in other reports.In this work,the as-prepared amorphous TiO₂ nanotube arrays on Ti foil was,firstly,annealed at a low temperature?250??,which not only maintain its original amorphous phase,but also improve its ability of resistance to corrosion in the electrolyte.Then,a low secondary anodic oxidation voltage?60 V?was applied at the bottom of the nanotube arrays to slowly open the hole and eventually peel off the arrays film.This could avoid the arising temperature of electrolyte caused by high voltage in our reaction system,which would accelerate the corrosion process of TiO₂ nanotube arrays in the fluorine-containing electrolyte and destroy its original morphology.When the time of secondary anodization lasted for 1.5 h,the corresponding N719 dye-sensitized solar cell based on FTO conductive glass substrate achieved a photoelectric conversion efficiency of 3.59%,which was the best output performance in the corresponding series of the controlled experiment.After the treatment of TiCl4,photo-electric conversion greatly enhances,and the conversion value the topsurface upright method is obviously higher than that via the bottom surface upright method.Eventually,the photoelectric conversion efficiency reached 5.11%.2.The preparation of TiO₂ nanotube array photoanode with high crystallization and"hierarchical structure":In the conventional crystallization procedure,the amorphous TiO₂ nanotube arrays were placed in a muffle furnace and annealed at 450?for 30 min.In this paper,a novel hydrothermal steam induced crystallization process was put forward to promote crystallization of the amorphous sample.In comparison to traditional process,the photoanode electrodes with hydrothermal steam induced crystallization treatment exhibits some excellent properties,such as long optical path length,fast electron transportation,large specific surface area,all of which could facilitate the adsorption of dyes and improve the short-circuit density(J_sc).When the treated temperature reached180?,the dye sensitized solar cell based on the featured?hierarchically structural?photoanode exhibited an impressive photoelectric conversion efficiency of 8.11%without any surface modification.When the treated temperature further increased to 200?,highly order structure of TNTAs was damaged with weakening light trapping capacity.Although the specific surface area has increased,the large charge recombination rate would lower the short-circuit density(J_sc)confirmed through EIS and OCVD measurement.