Preparation And Optimization Of Photoanodes And Their Application In Dye-sensitized Solar Cells

Dye-sensitized solar cells?DSSCs?,as a safe and reliable future energy source,have attracted wide attention because of the high efficiency and easy realization of the supply technology.DSSCs offer relatively low manufacturing cost,environmentally friendly production,and competitive conversion efficiency compared to traditional silicon solar cells.DSSCs are the best choice for indoor applications at low light intensity.The components of DSSCs include conductive substrate,dye,photoanode,catalyst and electrolyte.Each component has its own important role,among which the photoanode is the most important factors determining the power conversion efficiency.TiO₂ is cheap,rich and eco-friendly.Therefore,TiO₂ is one of the most common and key materials used in DSSCs,which is the electronic transmission medium in DSSCs.In the current study,the results show that TiO₂nanoparticles have good power conversion efficiency.However,the disadvantage of TiO₂nanoparticle photoanode possess zigzag diffusion pathway and lead to charge compounding,which reduces of electron collection efficiency and affects the power conversion efficiency.TiO₂ nanotubes have the characteristics of directly transmitting electron paths.Theoretically,TiO₂ nanotubes can greatly improve the photovoltaic performance,but the low specific surface area of the nanotubes reduces the amount of dye adsorption,resulting in the decrease of the light collection efficiency and the power conversion efficiency.In this paper,we will try to prepare a photoanode to balance charge transport and dye adsorption to optimize the photoelectric performance of DSSCs.The main research is to improve the light collection efficiency and electron collection efficiency by preparing TiO₂ photoanode with fast electron transport and high dye adsorption ability or by using barium titanate?BaTiO₃?and lanthanum-doped barium stannate?La-BaSnO₃?to combine with TiO₂ to prepare composite photoanode,which ultimately improve the photovoltaic performance of photoanode DSSCs.The main work and innovation are as follows.1.The well-aligned hierarchical TiO₂ nanotubes?HTNTs?have been synthesized by a one-step hydrothermal method employing potassium titanium oxalate,ethanol and H₂O,which are strongly adhered onto transparent conducting oxide glass.The preparation is straightforward,cheap and applicative for mass manufacture.The thickness of membranes is changed from 12 to 22?m by adjusting the reaction time.The HTNTs consist of one-dimensional?1D?long TiO₂ nanotube trunks and numerous short TiO₂ nanorod branches,which can balance surface area and charge transport.By employing optimized HTNTs for dye-sensitized solar cells,a remarkable power conversion efficiency of 9.89%is obtained.The result is superior to P25?8.34%?,because 1D trunk-1D branch structure of HTNTs offers the advantages of strong light-harvesting,directed electron transport,and efficient charge collection.The HTNTs may find an underlying application in the manufacture of photovoltaic devices.2.Here we have coupled ferroelectric Ba Ti O₃ with TiO₂ nanotubes to improve performance of dye-sensitized solar cells with the aid of ferroelectric polarization.Measurements with the use of UV-vis spectroscopy reveal that BaTiO₃ modified TiO₂nanotubes electrode shows more dye adsorption and greater fraction of light scattering.Moreover,the electron transport and recombination dynamics via electrochemical impedance spectroscopy and intensity modulated photocurrent/photovoltage spectroscopy measurements reveals that BaTiO₃ modified TiO₂ nanotubes cell has a faster electron transport,slower electron recombination and higher electron collection efficiency than original TiO₂ nanotubes cell.The ferroelectric BaTiO₃ modified TiO₂ nanotubes cell exhibits a power conversion efficiency of 10.15%,which is higher than that of original TiO₂ nanotubes cell?9.30%?.3.Dye-sensitized solar cell based on La-doped BaSnO₃/TiO₂ nanoparticles composite photoanode is studied.La-doped BaSnO₃ and TiO₂ nanoparticles are synthesized by hydrothermal treatment and the composite photoanodes are prepared through mixing various mass ratios of nanoparticles.The result shows that the composite photoanode can increase electron transfer efficiency.DSSC with S2?La-doped BaSnO₃ nanoparticles content is 10wt%?photoanode shows a relative high conversion efficiency of 10.5%because of the synergistic role of the high specific area of nanoparticles and rapid electron transfer of La-doped BaSnO₃.The research confirms that such a novel photoanode structure can suppress the electrons recombination process and increase the conversion efficiency effectively.