Studies On Preparation,Modification,Structure Optimization And Photoelectric Properties Of TiO₂ Photoanode Materials

In order to improve the photoelectric properties of dye-sensitized solar cells?DSSCs?,different titanium dioxide?TiO₂?photoanode films were prepared from the three aspects of preparation,modification and structure optimization.Preparation of highperformancephotoelectricTiO₂nanoparticlesinvlovingoptimization microemulsion method;Preparation modified TiO₂ photoanode films by graphene doping;Preparation of mesoporous TiO₂ thin films with high specific surface area and light harvesting to replace nanometer thin films.The photoelectric efficiency of the DSSCs based on the preparation materials were improved.The influence factors of the materials on the photoelectric properties of the cells were also studied.Preparation of high performance photoelectric TiO₂ nanoparticles involving optimization microemulsion methodTiO₂ nanoparticles were synthesized by using butyl titanate as the titanium source and were applied to photoanode of DSSCs.The hydrolysis reaction of the titanium ions under the microemulsion reaction system was studied.The selectivity of the reaction conditions such as refluxing,hydrothermal and pH of the rection system.Conditions of 75?reflux control was the optimization conditions of microemulsion method to prepare high efficiency photoelectric properties of TiO₂ nanoparticles.Hydrothermal treatment of TiO₂ microemulsion precursors reduced the photoelectric efficiency of DSSCs.The effects of different surfactants Tween 80 and Tx-100 and aqueous phase amounts on the particle size and size distribution of TiO₂ nanoparticles and their effects on the photoelectric properties were investigated.When Tx-100 as the surfactant,the molar ratio R of the aqueous phase to the butyl titanate was 35,the particle size distribution was narrow and the size was uniform?about 10-15 nm?,which was suitable as the DSSCs photoeletrode film nanomaterials.Microemulsion system of Tx-100/n-butanol/cyclohexane/water was appropriate for preparing DSSCs photocathode TiO₂ nanoparticles.TiO₂nanoparticles with good photoelectric properties were prepared by optimized reaction conditions and the conversion efficiency was 6.36%.Preparation modified TiO₂ photoanode films by graphene doping.The graphene-TiO₂?GN-TiO₂?photoanode doped graphene?GN?could be obtained by depositing the oxidized graphite?GO?solution onto the prepared TiO₂ photoanode films and heat treatment in an inert gas atmosphere.By controlling the deposition time of GO solution to control the doping amounts of GN,it was possible to prepare GN-TiO₂ photoanode with good repeatability,stable composition and no loss of GN.A series of material characterization of GN-TiO₂ films of photoanode and photoelectric properties of their assembled DSSCs were studied.It was found that GN could be used as a crystal conversion accelerator for TiO₂,changing anatase to rutile phase at 500?.The obtained photoanode of the mixed crystal structure could promote the electron transport and inhibit the electron recombination in the DSSCs,thereby improving the photoelectric properties of the cells.When the deposition time of GO solution was 6 h,the amount of GN in the GN-TiO₂ film was 3.12%.The performance of DSSCs got the best,and the photoelectric conversion efficiency was6.85%,which was 11.7%higher than that of blank TiO₂ photoanode.And the possible electron transport pathways in GN-DSSCs was proposed.Preparation of mesoporous TiO₂ thin films with high specific surface area and light harvesting to replace nanometer thin films.The mesoporous TiO₂?MT?materials were prepared by hydrothermal method using TiCl₄ as the titanium source,CTAB and P123 as template,controlling the ratio of the template to TiCl₄ and applied to DSSCs.It was found that different templates could synthesized MT materials with different crystal forms.CTAB could be used as template to obtain rutile MT material?MT-C material?,and P123 as template could get anatase MT material?MT-P material?.MT materials of micron-scale agglomeration ball structure were composed of a large number of nano-TiO₂ particles,compared to the control group of nano TiO₂materials,involved of a larger surface area,appropriate pore size of the diffusion of the electrolyte,and a scattering performance of the incident light.Due to less defects in TiO₂ lattice and more adsorption of-OH on the surface,MT-P photoanode showed longer electron lifetime and larger photocurrent than MT-C photoanode.The optimum performance of DSSCs in MT-DSSCs was 8.12%,which was 57.7%higher than that of P25-DSSCs.The photoelectric efficiency of DSSCs based on rutile MT-C photoanode increased by 5.4%,than that of DSSCs based on anatase nano TiO₂.